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Sample records for helium-strong star sigma

  1. The extremely rapid rotational braking of the magnetic helium-strong star HD 37776

    NASA Astrophysics Data System (ADS)

    Mikulášek, Z.; Krtička, J.; Henry, G. W.; Zverko, J.; Žižåovský, J.; Bohlender, D.; Romanyuk, I. I.; Janík, J.; Božić, H.; Korčáková, D.; Zejda, M.; Iliev, I. Kh.; Škoda, P.; Šlechta, M.; Gráf, T.; Netolický, M.; Ceniga, M.

    2008-07-01

    Context: Light and spectrum variations of the magnetic chemically peculiar (mCP) stars are explained by the oblique rigid rotator model with a rotation period usually assumed to be stable on a long time scale. A few exceptions, such as CU Vir or 56 Ari, have been reported as displaying an increase in their rotation period. A possible increase in the period of light and spectrum variations has also been suggested from observations of the helium-strong mCP star HD 37776 (V901 Ori). Aims: In this paper we attempt to confirm the possible period change of HD 37776 and discuss a possible origin of this change as a consequence of i) duplicity; ii) precession; iii) evolutionary changes; and iv) continuous/discrete/transient angular momentum loss. Methods: We analyse all available observations of the star obtained since 1976. These consist of 1707 photometric measurements obtained in uvby(β), (U)BV, V, BTVT, and Hp, including 550 of our own recent observations obtained in 2006 and 2007, 53 spectrophotometric measurements of the He I λ 4026 Å line, 66 equivalent width measurements of He I spectral lines from 23 CFHT spectrograms acquired in 1986, and 69 He I equivalent measurements from spectral lines present in 35 SAO Zeeman spectrograms taken between 1994 and 2002. All of these 1895 individual observations obtained by various techniques were processed simultaneously by means of specially developed robust codes. Results: We confirm the previously suspected gradual increase in the 1.5387 d period of HD 37776 and find that it has lengthened by a remarkable 17.7±0.7 s over the past 31 years. We also note that a decrease in the rate of the period change is not excluded by the data. The shapes of light curves in all colours were found to be invariable. Conclusions: After ruling out light-time effects in a binary star, precession of the rotational axis, and evolutionary changes as possible causes for the period change, we interpret this ongoing period increase as a braking of

  2. Modeling hybrid stars with an SU(3) nonlinear {sigma} model

    SciTech Connect

    Negreiros, Rodrigo; Dexheimer, V. A.; Schramm, S.

    2010-09-15

    We study the behavior of hybrid stars by using an extended hadronic and quark SU(3) nonlinear sigma model. The degrees of freedom change naturally, in this model, from hadrons to quarks as the density/temperature increases. At zero temperature, we reproduce massive neutron stars, which contain cores of hybrid matter of 2 km for the nonrotating case and 1.18 and 0.87 km, in the equatorial and polar directions, respectively, for stars that rotate at the Kepler frequency (physical cases lie in between). The cooling of such stars is also analyzed.

  3. A THIRD MASSIVE STAR COMPONENT IN THE {sigma} ORIONIS AB SYSTEM

    SciTech Connect

    Simon-Diaz, S.; Caballero, J. A.; Lorenzo, J.

    2011-11-20

    We report on the detection of a third massive star component in the {sigma} Orionis AB system, traditionally considered as a binary system. The system has been monitored by the IACOB Spectroscopic Survey of Northern Massive Stars program, obtaining 23 high-resolution FIES-NOT spectra with a time span of {approx}2.5 years. The analysis of the radial velocity curves of the two spectroscopic components observed in the spectra has allowed us to obtain the orbital parameters of the system, resulting in a high eccentric orbit (e {approx} 0.78) with an orbital period of 143.5 {+-} 0.5 days. This result implies the actual presence of three stars in the {sigma} Orionis AB system when combined with previous results obtained from the study of the astrometric orbit (with an estimated period of {approx}157 years).

  4. MOST OBSERVATIONS OF {sigma} Ori E: CHALLENGING THE CENTRIFUGAL BREAKOUT NARRATIVE

    SciTech Connect

    Townsend, R. H. D.; Rivinius, Th.; Rowe, J. F.; Moffat, A. F. J.; Matthews, J. M.; Kallinger, T.; Kuschnig, R.; Bohlender, D.; Neiner, C.; Telting, J. H.; Guenther, D. B.; Rucinski, S. M.; Sasselov, D.; Weiss, W. W.

    2013-05-20

    We present results from three weeks' photometric monitoring of the magnetic helium-strong star {sigma} Ori E using the Microvariability and Oscillations of Stars microsatellite. The star's light curve is dominated by twice-per-rotation eclipse-like dimmings arising when magnetospheric clouds transit across and occult the stellar disk. However, no evidence is found for any abrupt centrifugal breakout of plasma from the magnetosphere, either in the residual flux or in the depths of the light minima. Motivated by this finding we compare the observationally inferred magnetospheric mass against that predicted by a breakout analysis. The large discrepancy between the values leads us to argue that centrifugal breakout does not play a significant role in establishing the magnetospheric mass budget of {sigma} Ori E.

  5. In-flight star tracker SED 12 performances on-board the SIGMA experiment

    NASA Astrophysics Data System (ADS)

    Jouret, M.; Sebbag, I.; Vandermarcq, M. Q.; Krebs, J. P.; Le Goff, R.; Vilaire, D.; Tulet, M. M.

    The multimission SED 12 star tracker using a CCD matrix array has been designed by SODERN in cooperation with Matra-Marconi Space (F), respectively in charge of the optical head and software development for one and processing electronics and associated interfaces for the other. It has been selected for the French SIGMA experiment on board the Soviet GRANAT spacecraft which was launched on December 2, 1989. SIGMA is a French hard X-ray/medium energy gamma ray (30 keV-2 MeV) experiment aimed at imaging selected regions of the sky with a resolution of about one arc minute and has been developed and manufactured under the overall management of CNES (the French National Space Agency). The experiment package demands a pointing stability of a few arc-seconds over periods of several hours corresponding to the long exposure times required to build up images of the target gamma sources. As the GRANAT satellite is not able to maintain such high precision attitude stability, incorporated into the gamma telescope are two SED 12 sensors aligned together with the telescope. The development of this star tracker was started in 1985 under a CNES contract, the qualification was successfully performed in 1987 and the delivery of 2 flight models was completed in 1988. The expected life time of the experiment was 1.5 year and since the launch date the mission is still operating without any significant performance degradation of the star tracker. The purpose of this paper is, on the one hand to present the multimission tracker design trade-offs and the SED 12 device: description, main features, operating modes and performances, and on the other hand, to analyze the on ground and in-flight star tracker data. This analysis has been mainly led according to the following criteria: performance results in angular position and magnitude measurement, dark current evolution versus time and radiation dose, correlation between visual and instrumental magnitudes.

  6. Discovery of young, isolated planetary mass objects in the final sigma Orionis star cluster.

    PubMed

    Zapatero Osorio, M R; Béjar, V J; Martín, E L; Rebolo, R; Barrado y Navascués, D; Bailer-Jones, C A; Mundt, R

    2000-10-01

    We present the discovery by optical and near-infrared imaging of an extremely red, low-luminosity population of isolated objects in the young, nearby stellar cluster around the multiple, massive star final sigma Orionis. The proximity (352 parsecs), youth (1 million to 5 million years), and low internal extinction make this cluster an ideal site to explore the substellar domain from the hydrogen mass limit down to a few Jupiter masses. Optical and near-infrared low-resolution spectroscopy of three of these objects confirms the very cool spectral energy distribution (atmospheric effective temperatures of 1700 to 2200 kelvin) expected for cluster members with masses in the range 5 to 15 times that of Jupiter. Like the planets of the solar system, these objects are unable to sustain stable nuclear burning in their interiors, but in contrast they are not bound to stars. This new kind of isolated giant planet, which apparently forms on time scales of less than a few million years, offers a challenge to our understanding of the formation processes of planetary mass objects.

  7. Lithium and Hα in stars and brown dwarfs of sigma Orionis.

    NASA Astrophysics Data System (ADS)

    Zapatero Osorio, M. R.; Béjar, V. J. S.; Pavlenko, Ya.; Rebolo, R.; Allende Prieto, C.; Martín, E. L.; García López, R. J.

    2002-03-01

    We present intermediate- and low-resolution optical spectra around Hα and Li I lambda 6708 Åfor a sample of 25 low mass stars and 2 brown dwarfs with confirmed membership in the pre-main sequence stellar sigma Orionis cluster. Our observations are intended to investigate the age of the cluster. The spectral types derived for our target sample are found to be in the range K6-M8.5, which corresponds to a mass interval of roughly 1.2-0.02 Msun on the basis of state-of-the-art evolutionary models. Radial velocities (except for one object) are found to be consistent with membership in the Orion complex. All cluster members show considerable Hα emission and the Li I resonance doublet in absorption, which is typical of very young ages. We find that our pseudo-equivalent widths of Hα and Li I (measured relative to the observed local pseudo-continuum formed by molecular absorptions) appear rather dispersed (and intense in the case of Hα ) for objects cooler than M3.5 spectral class, occurring at the approximate mass where low mass stars are expected to become fully convective. The least massive brown dwarf in our sample, S Ori 45 (M8.5, ~ 0.02 Msun), displays variable Hα emission and a radial velocity that differs from the cluster mean velocity. Tentative detection of forbidden lines in emission indicates that this brown dwarf may be accreting mass from a surrounding disk. We also present recent computations of Li I lambda 6708 Åcurves of growth for low gravities and for the temperature interval (about 4000-2600 K) of our sample. The comparison of our observations to these computations allows us to infer that no lithium depletion has yet taken place in sigma Orionis, and that the observed pseudo-equivalent widths are consistent with a cluster initial lithium abundance close to the cosmic value. Hence, the upper limit to the sigma Orionis cluster age can be set at 8 Myr, with a most likely value around 2-4 Myr. Based on observations made with the following telescopes

  8. Spectrophotometry of peculiar B and A stars. XVIII - The helium rich variable stars HR 1890, Sigma Orionis E, and HD 37776

    NASA Technical Reports Server (NTRS)

    Adelman, S. J.; Pyper, D. M.

    1985-01-01

    Optical region spectrophotometry at 3300-7850 A has been obtained for three helium rich stars, HR 1890, Sigma Ori E, and HD 37776, of the Orion OB1 Association. New uvby-beta photometry of HR 1890 and HD 37776 as well as published data are also used to investigate the variability of these stars. A new period of 1.53862 days was determined for HD 37776. For all three stars H-beta varies in antiphase with strong He I lines. The spectrophotometric bandpass containing the strong He I line at 4471 A varies in phase with the R index of Pedersen and Thomsen (1977). Evidence is found for weak absorption features which appear to be an extension of the 5200 A feature seen in cooler CP stars.

  9. Measurements of anisotropy in the cosmic microwave background radiation at degree angular scales near the stars Sigma Herculis and Iota Draconis

    NASA Technical Reports Server (NTRS)

    Clapp, A. C.; Devlin, M. J.; Gundersen, J. O.; Hagmann, C. A.; Hristov, V. V.; Lange, A. E.; Lim, M.; Lubin, P. M.; Mauskopf, P. D.; Meinhold, P. R.

    1994-01-01

    We present results from two four-frequency observations centered near the stars Sigma Herculis and Iota Draconis during the fourth flight of the Millimeter-wave Anisotropy eXperiment (MAX). The observations were made of 6 deg x 0.6 deg strips of the sky with a 1.4 deg peak to peak sinusoidal chop in all bands. The full width at half maximum (FWHM) beam sizes were calculated 0.55 deg +/- 0.05 deg at 3.5/cm and a 0.75 deg +/- 0.05 deg at 6, 9, and 14/cm. Significant correlated structures were observed at 3.5, 6, and 9/cm. The spectra of these signals are inconsistent with thermal emission from known interstellar dust populations. The extrapolated amplitudes of synchrotron and free-free emission are too small to account for the amplitude of the observed structures. If the observed structures are attributed to cosmic microwave background (CMB) anisotropy with a Gaussian autocorrelation function and a coherence angle of 25 min, then the most probable values at Delta T/T(sub CMB) = 3.1 (sup +1.7 sub -1.3) x 10(exp -5) for the Sigma Herculis scan, and Delta T/T(sub CMB) = 3.3(sup +1.1 sub -1.1) x 10(exp -5) for the Iota Draconis scan (95% confidence upper, lower limits).

  10. Sensitivity of neutron radii in a {sup 208}Pb nucleus and a neutron star to nucleon-{sigma}-{rho} coupling corrections in relativistic mean field theory

    SciTech Connect

    Shen, G.; Li, J.; Hillhouse, G.C.; Meng, J.

    2005-01-01

    We study the sensitivity of the neutron skin thickness S in a {sup 208}Pb nucleus to the addition of nucleon-{sigma}-{rho} coupling corrections to a selection (PK1, NL3, S271, and Z271) of interactions in a relativistic mean field model. The PK1 and NL3 effective interactions lead to a minimum value of S= 0.16 fm in comparison with the original value of S= 0.28 fm. The S271 and Z271 effective interactions yield even smaller values of S= 0.11 fm, which are similar to those for nonrelativistic mean field models. A precise measurement of the neutron radius, and therefore S, in {sup 208}Pb will place an important constraint on both relativistic and nonrelativistic mean field models. We also study the correlation between the radius of a 1.4-solar-mass neutron star and S.

  11. THE DISCOVERY OF A STRONG MAGNETIC FIELD AND COROTATING MAGNETOSPHERE IN THE HELIUM-WEAK STAR HD 176582

    SciTech Connect

    Bohlender, David A.; Monin, Dmitry

    2011-05-15

    We report the detection of a strong, reversing magnetic field and variable H{alpha} emission in the bright helium-weak star HD 176582 (HR 7185). Spectrum, magnetic, and photometric variability of the star are all consistent with a precisely determined period of 1.5819840 {+-} 0.0000030 days which we assume to be the rotation period of the star. From the magnetic field curve, and assuming a simple dipolar field geometry, we derive a polar field strength of approximately 7 kG and a lower limit of 52 deg. for the inclination of the rotation axis. However, based on the behavior of the H{alpha} emission, we adopt a large inclination angle of 85 deg. and this leads to a large magnetic obliquity of 77{sup 0}. The H{alpha} emission arises from two distinct regions located at the intersections of the magnetic and rotation equators and which corotate with the star at a distance of about 3.5 R{sub *} above its surface. We estimate that the emitting regions have radial and meridional sizes on the order of 2 R{sub *} and azimuthal extents (perpendicular to the magnetic equator) of less than approximately 0.6 R{sub *}. HD 176582 therefore appears to show many of the cool magnetospheric phenomena as that displayed by other magnetic helium-weak and helium-strong stars such as the prototypical helium-strong star {sigma} Ori E. The observations are consistent with current models of magnetically confined winds and rigidly rotating magnetospheres for magnetic Bp stars.

  12. Six sigma.

    PubMed

    Carter, Pam

    2010-12-01

    When I was first introduced to the Six Sigma process, I resisted it with every ounce of energy I had. I continuously fabricated reasons so that I was unable to complete the training that my company required. When it came time for my performance review, I could not hide the truth from my manager; I had not completed the required training. It was then that I began my journey into the world of Six Sigma. Once I understood that a black belt and a green belt certification had nothing to do with karate, I felt much better. PMID:21117529

  13. Special types of B stars. [Beta Cephei and peculiar B stars

    NASA Technical Reports Server (NTRS)

    Lesh, J. R.

    1982-01-01

    The properties of the Beta Cephei stars are examined with emphasis on spectral types, luminosities, periods, and light and velocity variations. Typical members of the group and their position in the observational and theoretical HR diagram are discussed. Those B stars with anomalous spectra (chemically peculiar) are considered including hot subdwarfs, extreme helium, weak helium, strong helium, helium variable, magnetic and mercury-manganese stars.

  14. Very low-luminosity Class I/Flat outflow sources in sigma Orionis: Clues to alternative formation mechanisms for very low-mass stars

    NASA Astrophysics Data System (ADS)

    Riaz, Basmah; Whelan, E.; Thompson, M.; Vorobyov, E.; Lodieu, N.

    2015-01-01

    We present an optical through sub-millimetre multi-wavelength study of two very low-luminosity Class I/Flat systems, Mayrit 1701117 and Mayrit 1082188, in the sigma Orionis cluster. We performed moderate resolution (R 1000) optical ( 0.4-0.9mu) spectroscopy with the TWIN spectrograph at the Calar Alto 3.5-m telescope. The spectra for both sources show prominent emission in accretion- and outflow-associated lines. The mean accretion rate measured from multiple line diagnostics is 6.4x10^{-10} Msun/yr for Mayrit 1701117, and 2.5x10^{-10} Msun/yr for Mayrit 1082188. The outflow mass loss rates for the two systems are similar and estimated to be 1x10^{-9} Msun/yr. The activity rates are within the range observed for low-mass Class I protostars. We obtained sub-millimetre continuum observations with the Submillimetre Common-User Bolometer Array (SCUBA-2) bolometer at the James Clerk Maxwell Telescope. Both objects are detected at a >5-sigma level in the SCUBA-2 850mu band. The bolometric luminosity of the targets as measured from the observed spectral energy distribution over 0.8-850mu is 0.18+/-0.04 Lsun for Mayrit 1701117, and 0.16+/-0.03 Lsun for Mayrit 1082188, and is in the very low-mass range. The total dust+gas mass derived from sub-millimetre fluxes is 36 M_Jup and 22 M_Jup for Mayrit 1701117 and Mayrit 1082188, respectively. There is the possibility that some of the envelope material might be dissipated by the strong outflows driven by these sources, resulting in a final mass of the system close to or below the sub-stellar limit. Given the membership of these objects in a relatively evolved cluster of 3 Myr of age, we consider an alternate formation mechanism in the context of the `hybrid' model of disk fragmentation, followed by ejection of a gaseous clump.

  15. Stars

    NASA Astrophysics Data System (ADS)

    Capelato, Hugo Vicente

    1999-01-01

    We will begin our study with a more or less superficial inspection of the "forest" of stars that we see in the skies. The first thing we notice is that, as sources of light, they are much weaker than the Sun. Second, their apparent colors vary; from a bluish-white in most of them to a reddish-yellow, which is rarer. There is also a third aspect, though it is not very obvious to the naked eye: most of the stars group themselves in small families of two, three or more members. A good example is the Alpha Centauri, the closest star to us, which, in fact, is a triple system of stars. Another is the group of 7 stars that make up the Pleiades, which will be discussed later on. In fact, almost half of the stars are double systems with only two members, called binary stars. Most of these double stars, though together, are separated by several astronomical units (one astronomical unit, AU, is the distance from Earth to the sun: see Chapter 1), and revolve around each other over periods of several years. And yet the revolutions of some binary stars, separated by much smaller distances, occur in only a few hours! These stars are so close to each other that they can share enveloping material. Often this exchange occurs in a somewhat violent manner. Local explosions may occur, expelling matter away from the system. In other binary systems, where one of the components is a very compact, dense star, companion material flows more calmly, making up a light disk around the compact star.

  16. Supersymmetric sigma models

    SciTech Connect

    Bagger, J.A.

    1984-09-01

    We begin to construct the most general supersymmetric Lagrangians in one, two and four dimensions. We find that the matter couplings have a natural interpretation in the language of the nonlinear sigma model.

  17. Six Sigma pricing.

    PubMed

    Sodhi, ManMohan S; Sodhi, Navdeep S

    2005-05-01

    Many companies are now good at managing costs and wringing out manufacturing efficiencies. The TQM movement and the disciplines of Six Sigma have seen to that. But the discipline so often brought to the cost side of the business equation is found far less commonly on the revenue side. The authors describe how a global manufacturer of industrial equipment, which they call Acme Incorporated, recently applied Six Sigma to one major revenue related activity--the price-setting process. It seemed to Acme's executives that pricing closely resembled many manufacturing processes. So, with the help of a Six Sigma black belt from manufacturing, a manager from Acme's pricing division recruited a team to carry out the five Six Sigma steps: Define what constitutes a defect. At Acme, a defect was an item sold at an unauthorized price. Gather data and prepare it for analysis. That involved mapping out the existing pricing-agreement process. Analyze the data. The team identified the ways in which people failed to carry out or assert effective control at each stage. Recommend modifications to the existing process. The team sought to decrease the number of unapproved prices without creating an onerous approval apparatus. Create controls. This step enabled Acme to sustain and extend the improvements in its pricing procedures. As a result of the changes, Acme earned dollar 6 million in additional revenue on one product line alone in the six months following implementation--money that went straight to the bottom line. At the same time, the company removed much of the organizational friction that had long bedeviled its pricing process. Other companies can benefit from Acme's experience as they look for ways to exercise price control without alienating customers. PMID:15929409

  18. Six Sigma pricing.

    PubMed

    Sodhi, ManMohan S; Sodhi, Navdeep S

    2005-05-01

    Many companies are now good at managing costs and wringing out manufacturing efficiencies. The TQM movement and the disciplines of Six Sigma have seen to that. But the discipline so often brought to the cost side of the business equation is found far less commonly on the revenue side. The authors describe how a global manufacturer of industrial equipment, which they call Acme Incorporated, recently applied Six Sigma to one major revenue related activity--the price-setting process. It seemed to Acme's executives that pricing closely resembled many manufacturing processes. So, with the help of a Six Sigma black belt from manufacturing, a manager from Acme's pricing division recruited a team to carry out the five Six Sigma steps: Define what constitutes a defect. At Acme, a defect was an item sold at an unauthorized price. Gather data and prepare it for analysis. That involved mapping out the existing pricing-agreement process. Analyze the data. The team identified the ways in which people failed to carry out or assert effective control at each stage. Recommend modifications to the existing process. The team sought to decrease the number of unapproved prices without creating an onerous approval apparatus. Create controls. This step enabled Acme to sustain and extend the improvements in its pricing procedures. As a result of the changes, Acme earned dollar 6 million in additional revenue on one product line alone in the six months following implementation--money that went straight to the bottom line. At the same time, the company removed much of the organizational friction that had long bedeviled its pricing process. Other companies can benefit from Acme's experience as they look for ways to exercise price control without alienating customers.

  19. The Architects of Modern Physics & Sigma Pi Sigma Heritage

    NASA Astrophysics Data System (ADS)

    White, Gary

    2004-10-01

    While the tools of modern physics were being honed throughout the last century, physicist Marsh W. White (no relation) served as the installation officer for over 200 chapters of the physics honor society, Sigma Pi Sigma. Years earlier, though, his 1926 thesis ``The Energy of High Velocity Electrons'' served as a direct test of one of Einstein's most radical 1905 ideas. The ``red books'' of Sigma Pi Sigma, into which all inductees pen their names, include some of the most talented quantum mechanics of the 20th century, such as Edward Teller and George Gamow. In this talk, I will review these and other links between Sigma Pi Sigma and some of the architects of modern physics.

  20. Observation of the Heavy Baryons Sigma b and Sigma b*.

    PubMed

    Aaltonen, T; Abulencia, A; Adelman, J; Affolder, T; Akimoto, T; Albrow, M G; Amerio, S; Amidei, D; Anastassov, A; Anikeev, K; Annovi, A; Antos, J; Aoki, M; Apollinari, G; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Aurisano, A; Azfar, F; Azzi-Bacchetta, P; Azzurri, P; Bacchetta, N; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Baroiant, S; Bartsch, V; Bauer, G; Beauchemin, P-H; Bedeschi, F; Behari, S; Bellettini, G; Bellinger, J; Belloni, A; Benjamin, D; Beretvas, A; Beringer, J; Berry, T; Bhatti, A; Binkley, M; Bisello, D; Bizjak, I; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bolla, G; Bolshov, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, J; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Byrum, K L; Cabrera, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carillo, S; Carlsmith, D; Carosi, R; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; 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Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garcia, J E; Garberson, F; Garfinkel, A F; Gay, C; Gerberich, H; Gerdes, D; Giagu, S; Giannetti, P; Gibson, K; Gimmell, J L; Ginsburg, C; Giokaris, N; Giordani, M; Giromini, P; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Goldstein, J; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Grinstein, S; Grosso-Pilcher, C; Grundler, U; Guimaraes da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Hamilton, A; Han, B-Y; Han, J Y; Handler, R; Happacher, F; Hara, K; Hare, D; Hare, M; Harper, S; Harr, R F; Harris, R M; Hartz, M; Hatakeyama, K; Hauser, J; Hays, C; Heck, M; Heijboer, A; Heinemann, B; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hidas, D; Hill, C S; Hirschbuehl, D; Hocker, A; Holloway, A; Hou, S; Houlden, M; Hsu, S-C; Huffman, B T; Hughes, R E; Husemann, U; Huston, J; Incandela, J; Introzzi, G; Iori, M; Ivanov, A; Iyutin, B; James, E; Jang, D; Jayatilaka, B; Jeans, D; Jeon, E J; Jindariani, S; Johnson, W; Jones, M; Joo, K K; Jun, S Y; Jung, J E; Junk, T R; Kamon, T; Karchin, P E; Kato, Y; Kemp, Y; Kephart, R; Kerzel, U; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirsch, L; Klimenko, S; Klute, M; Knuteson, B; Ko, B R; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kraan, A C; Kraus, J; Kreps, M; Kroll, J; Krumnack, N; Kruse, M; Krutelyov, V; Kubo, T; Kuhlmann, S E; Kuhr, T; Kulkarni, N P; Kusakabe, Y; Kwang, S; Laasanen, A T; Lai, S; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; LeCompte, T; Lee, J; Lee, J; Lee, Y J; Lee, S W; Lefèvre, R; Leonardo, N; Leone, S; Levy, S; Lewis, J D; Lin, C; Lin, C S; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, T; Lockyer, N S; Loginov, A; Loreti, M; Lu, R-S; Lucchesi, D; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; Lytken, E; Mack, P; MacQueen, D; Madrak, R; Maeshima, K; Makhoul, K; Maki, T; Maksimovic, P; Malde, S; Malik, S; Manca, G; Manousakis, A; Margaroli, F; Marginean, R; Marino, C; Marino, C P; Martin, A; Martin, M; Martin, V; Martínez, M; Martínez-Ballarín, R; Maruyama, T; Mastrandrea, P; Masubuchi, T; Matsunaga, H; Mattson, M E; Mazini, R; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Menzemer, S; Menzione, A; Merkel, P; Mesropian, C; Messina, A; Miao, T; Miladinovic, N; Miles, J; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyamoto, A; Moed, S; Moggi, N; Mohr, B; Moon, C S; Moore, R; Morello, M; Movilla Fernandez, P; Mülmenstädt, J; Mukherjee, A; Muller, Th; Mumford, R; Murat, P; Mussini, M; Nachtman, J; Nagano, A; Naganoma, J; Nakamura, K; Nakano, I; Napier, A; Necula, V; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Norniella, O; Nurse, E; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Oldeman, R; Orava, R; Osterberg, K; Pagliarone, C; Palencia, E; Papadimitriou, V; Papaikonomou, A; Paramonov, A A; Parks, B; Pashapour, S; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Piedra, J; Pinera, L; Pitts, K; Plager, C; Pondrom, L; Portell, X; Poukhov, O; Pounder, N; Prakoshyn, F; Pronko, A; Proudfoot, J; Ptohos, F; Punzi, G; Pursley, J; Rademacker, J; Rahaman, A; Ramakrishnan, V; Ranjan, N; Redondo, I; Reisert, B; Rekovic, V; Renton, P; Rescigno, M; Richter, S; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rossin, R; Roy, P; Ruiz, A; Russ, J; Rusu, V; Saarikko, H; Safonov, A; Sakumoto, W K; Salamanna, G; Saltó, O; Santi, L; Sarkar, S; Sartori, L; Sato, K; Savard, P; Savoy-Navarro, A; Scheidle, T; Schlabach, P; Schmidt, E E; Schmidt, M A; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scott, A L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sexton-Kennedy, L; Sfyrla, A; Shalhout, S Z; Shapiro, M D; Shears, T; Shepard, P F; Sherman, D; Shimojima, M; Shochet, M; Shon, Y; Shreyber, I; Sidoti, A; Sinervo, P; Sisakyan, A; Slaughter, A J; Slaunwhite, J; Sliwa, K; Smith, J R; Snider, F D; Snihur, R; Soderberg, M; Soha, A; Somalwar, S; Sorin, V; Spalding, J; Spinella, F; Spreitzer, T; Squillacioti, P; Stanitzki, M; Staveris-Polykalas, A; St Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Stuart, D; Suh, J S; Sukhanov, A; Sun, H; Suslov, I; Suzuki, T; Taffard, A; Takashima, R; Takeuchi, Y; Tanaka, R; Tecchio, M; Teng, P K; Terashi, K; Tesarek, R J; Thom, J; Thompson, A S; Thomson, E; Tipton, P; Tiwari, V; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Tourneur, S; Trischuk, W; Tsuno, S; Tu, Y; Turini, N; Ukegawa, F; Uozumi, S; Vallecorsa, S; van Remortel, N; Varganov, A; Vataga, E; Vazquez, F; Velev, G; Vellidis, C; Veramendi, G; Veszpremi, V; Vidal, M; Vidal, R; Vila, I; Vilar, R; Vine, T; Vogel, M; Vollrath, I; Volobouev, I; Volpi, G; Würthwein, F; Wagner, P; Wagner, R G; Wagner, R L; Wagner, J; Wagner, W; Wallny, R; Wang, S M; Warburton, A; Waters, D; Weinberger, M; Wester, W C; Whitehouse, B; Whiteson, D; Wicklund, A B; Wicklund, E; Williams, G; Williams, H H; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, C; Wright, T; Wu, X; Wynne, S M; Yagil, A; Yamamoto, K; Yamaoka, J; Yamashita, T; Yang, C; Yang, U K; Yang, Y C; Yao, W M; Yeh, G P; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanello, L; Zanetti, A; Zaw, I; Zhang, X; Zhou, J; Zucchelli, S

    2007-11-16

    We report an observation of new bottom baryons produced in pp collisions at the Tevatron. Using 1.1 fb(-1) of data collected by the CDF II detector, we observe four Lambda b 0 pi+/- resonances in the fully reconstructed decay mode Lambda b 0-->Lambda c + pi-, where Lambda c+-->pK* pi+. We interpret these states as the Sigma b(*)+/- baryons and measure the following masses: m Sigma b+=5807.8 -2.2 +2.0(stat.)+/-1.7(syst.) MeV/c2, m Sigma b- =5815.2+/-1.0(stat.)+/-1.7(syst.) MeV/c2, and m(Sigma b*)-m(Sigma b)=21.2-1.9 +2.0(stat.)-0.3+0.4(syst.) MeV/c2.

  1. Sigma receptors and cocaine abuse.

    PubMed

    Narayanan, Sanju; Mesangeau, Christophe; Poupaert, Jacques H; McCurdy, Christopher R

    2011-01-01

    Sigma receptors have been well documented as a protein target for cocaine and have been shown to be involved in the toxic and stimulant actions of cocaine. Strategies to reduce the access of cocaine to sigma receptors have included antisense oligonucleotides to the sigma-1 receptor protein as well as small molecule ligand with affinity for sigma receptor sites. These results have been encouraging as novel protein targets that can attenuate the actions of cocaine are desperately needed as there are currently no medications approved for treatment of cocaine toxicity or addiction. Many years of research in this area have yet to produce an effective treatment and much focus was on dopamine systems. A flurry of research has been carried out to elucidate the role of sigma receptors in the blockade of cocaine effects but this research has yet to yield a clinical agent. This review summarizes the work to date on the linkage of sigma receptors and the actions of cocaine and the progress that has been made with regard to small molecules. Although there is still a lack of an agent in clinical trials with a sigma receptor mechanism of action, work is progressing and the ligands are becoming more selective for sigma systems and the potential remains high. PMID:21050176

  2. {sigma} Hyperons in the Nucleus

    SciTech Connect

    Bart, S.; Chrien, R. E.; Franklin, W. A.; Fukuda, T.; Hayano, R. S.; Hicks, K.; Hungerford, E. V.; Michael, R.; Miyachi, T.; Nagae, T.

    1999-12-20

    A search for {sigma} hypernuclear states in p -shell hypernuclei has been performed with the Moby Dick spectrometer and the low energy separated beam (LESB-2) at the Brookhaven Alternating Gradient Synchrotron (BNL AGS). Unlike some previously published reports, no narrow states have been observed for targets of {sup 6}Li and {sup 9}Be in (K{sup -}, {pi}{sup {+-}}) reactions, either for bound state or continuum regions. Together with the previously reported J=0 , T=1/2 bound state in {sup 4}{sub {sigma}} He , these results demonstrate the crucial role of isospin in {sigma} hypernuclei. (c) 1999 The American Physical Society.

  3. The sigma factors of Bacillus subtilis.

    PubMed Central

    Haldenwang, W G

    1995-01-01

    The specificity of DNA-dependent RNA polymerase for target promotes is largely due to the replaceable sigma subunit that it carries. Multiple sigma proteins, each conferring a unique promoter preference on RNA polymerase, are likely to be present in all bacteria; however, their abundance and diversity have been best characterized in Bacillus subtilis, the bacterium in which multiple sigma factors were first discovered. The 10 sigma factors thus far identified in B. subtilis directly contribute to the bacterium's ability to control gene expression. These proteins are not merely necessary for the expression of those operons whose promoters they recognize; in many instances, their appearance within the cell is sufficient to activate these operons. This review describes the discovery of each of the known B. subtilis sigma factors, their characteristics, the regulons they direct, and the complex restrictions placed on their synthesis and activities. These controls include the anticipated transcriptional regulation that modulates the expression of the sigma factor structural genes but, in the case of several of the B. subtilis sigma factors, go beyond this, adding novel posttranslational restraints on sigma factor activity. Two of the sigma factors (sigma E and sigma K) are, for example, synthesized as inactive precursor proteins. Their activities are kept in check by "pro-protein" sequences which are cleaved from the precursor molecules in response to intercellular cues. Other sigma factors (sigma B, sigma F, and sigma G) are inhibited by "anti-sigma factor" proteins that sequester them into complexes which block their ability to form RNA polymerase holoenzymes. The anti-sigma factors are, in turn, opposed by additional proteins which participate in the sigma factors' release. The devices used to control sigma factor activity in B, subtilis may prove to be as widespread as multiple sigma factors themselves, providing ways of coupling sigma factor activation to

  4. Running Head: Implementing Six Sigma Efforts

    ERIC Educational Resources Information Center

    Lindsay, Jamie Eleaitia Mae

    2005-01-01

    Six Sigma is an organization wide program that provides common set of goals, language, and methodology for improving the overall quality of the processes within the organization (Davis & Heineke 2004). Six Sigma main concern is for the customer. What will the customers want? Need? Six Sigma has a model that helps Sigma get implemented DMAIC model…

  5. Positioning of sigma(S), the stationary phase sigma factor, in Escherichia coli RNA polymerase-promoter open complexes.

    PubMed

    Colland, F; Fujita, N; Kotlarz, D; Bown, J A; Meares, C F; Ishihama, A; Kolb, A

    1999-07-15

    The sigma(S) subunit of RNA polymerase is the master regulator of the general stress response in Escherichia coli and is required for promoter recognition of many stationary phase genes. We have analysed open complexes of Esigma(S) RNA polymerase, using sigma(S) derivatives carrying single cysteine residues at nine different positions to which the reagent FeBABE has been tethered. All holoenzymes but one formed transcriptionally active open complexes at three different promoters (osmY, galP1 and lacUV5). The chemical nuclease FeBABE can cleave DNA in proximity to the chelate. The overall cutting pattern of Esigma(S) open complexes does not depend on the nature of the promoter and is similar to that obtained with Esigma(70), but extends towards the downstream part of the promoter. The strongest cleavages are observed with FeBABE positioned on cysteines in regions 2.2 to 3.1. In contrast to sigma(70), region 2.1 of sigma(S) appears to be far from DNA. Region 4.2 of sigma(S) appears less accessible than its counterpart in sigma(70) and FeBABE positioned in the turn of the helix-turn-helix (HTH) motif in region 4.2 reacts only weakly with the -35 promoter element. This provides a structural basis for the minor role of the -35 sequence in sigma(S)-dependent promoter recognition.

  6. The sausage sigma model revisited

    NASA Astrophysics Data System (ADS)

    Suneeta, Vardarajan

    2015-06-01

    Fateev’s sausage sigma models in two and three dimensions are known to be integrable. We study their stability under renormalization group (RG) flow in the target space by using results from the mathematics of Ricci flow. We show that the three-dimensional sausage is unstable, whereas the two-dimensional sausage appears to be stable at least at leading order as it approaches the sphere. We speculate that the stability results obtained are linked to the classification of ancient solutions to Ricci flow (i.e., sigma models that are nonperturbative in the infrared regime) in two and three dimensions. We also describe a class of perturbations of the three-dimensional sausage (with the same continuous symmetries) which remarkably decouple. This indicates that there could be a new solution to RG flow, which is described at least perturbatively as a deformation of the sausage.

  7. Lean six sigma in healthcare.

    PubMed

    de Koning, Henk; Verver, John P S; van den Heuvel, Jaap; Bisgaard, Soren; Does, Ronald J M M

    2006-01-01

    Healthcare, as with any other service operation, requires systematic innovation efforts to remain competitive, cost efficient, and up-to-date. This article outlines a methodology and presents examples to illustrate how principles of Lean Thinking and Six Sigma can be combined to provide an effective framework for producing systematic innovation efforts in healthcare. Controlling healthcare cost increases, improving quality, and providing better healthcare are some of the benefits of this approach.

  8. Sigma Factors for Cyanobacterial Transcription

    PubMed Central

    Imamura, Sousuke; Asayama, Munehiko

    2009-01-01

    Cyanobacteria are photosynthesizing microorganisms that can be used as a model for analyzing gene expression. The expression of genes involves transcription and translation. Transcription is performed by the RNA polymerase (RNAP) holoenzyme, comprising a core enzyme and a sigma (σ) factor which confers promoter selectivity. The unique structure, expression, and function of cyanobacterial σ factors (and RNAP core subunits) are summarized here based on studies, reported previously. The types of promoter recognized by the σ factors are also discussed with regard to transcriptional regulation. PMID:19838335

  9. STADAN antenna gain calibration using radio stars

    NASA Technical Reports Server (NTRS)

    Taylor, R. E.

    1972-01-01

    An antenna gain measurement method was developed which utilizes a signal emitted from a radio star to determine absolute antenna gain at 136 MHz and 400 MHz for antennas in the STADAN network. An error analysis of the radio star method shows that the overall standard deviation uncertainty in antenna gain is + or - 0.6 db (1 sigma).

  10. Structural determinants of sigma receptor affinity

    SciTech Connect

    Largent, B.L.; Wikstroem, H.G.; Gundlach, A.L.; Snyder, S.H.

    1987-12-01

    The structural determinants of sigma receptor affinity have been evaluated by examining a wide range of compounds related to opioids, neuroleptics, and phenylpiperidine dopaminergic structures for affinity at sigma receptor-binding sites labeled with (+)-(/sup 3/H)3-PPP. Among opioid compounds, requirements for sigma receptor affinity differ strikingly from the determinants of affinity for conventional opiate receptors. Sigma sites display reverse stereoselectivity to classical opiate receptors. Multi-ringed opiate-related compounds such as morphine and naloxone have negligible affinity for sigma sites, with the highest sigma receptor affinity apparent for benzomorphans which lack the C ring of opioids. Highest affinity among opioids and other compounds occurs with more lipophilic N-substituents. This feature is particularly striking among the 3-PPP derivatives as well as the opioids. The butyrophenone haloperidol is the most potent drug at sigma receptors we have detected. Among the series of butyrophenones, receptor affinity is primarily associated with the 4-phenylpiperidine moiety. Conformational calculations for various compounds indicate a fairly wide range of tolerance for distances between the aromatic ring and the amine nitrogen, which may account for the potency at sigma receptors of structures of considerable diversity. Among the wide range of structures that bind to sigma receptor-binding sites, the common pharmacophore associated with high receptor affinity is a phenylpiperidine with a lipophilic N-substituent.

  11. Density-Dependent Properties of Hadronic Matter in the self-consistent Chiral ({sigma},{pi},{omega}) Mean-Field Model

    SciTech Connect

    Uechi, Schun T.; Uechi, Hiroshi

    2011-05-06

    Density-dependent relations among saturation properties of symmetric nuclear matter and properties of hadronic stars are discussed by applying the conserving chiral nonlinear ({sigma},{pi},{omega}) hadronic mean-field theory. The chiral nonlinear ({sigma},{pi},{omega}) mean-field theory is an extension of the conserving nonlinear (nonchiral) {sigma}-{omega} hadronic mean-field theory which is thermodynamically consistent, relativistic and is a Lorentz-covariant mean-field theory of hadrons. In the extended chiral ({sigma},{pi},{omega}) mean-field model, all the masses of hadrons are produced by the breaking of chiral symmetry, which is different from other conventional chiral partner models. By comparing both nonchiral and chiral mean-field approximations, the effects of the chiral symmetry breaking mechanism on the mass of {sigma}-meson, coefficients of nonlinear interactions and Fermi-liquid properties are investigated in nuclear matter and neutron stars.

  12. POLARIMETRIC OBSERVATIONS OF {sigma} ORIONIS E

    SciTech Connect

    Carciofi, A. C.; Faes, D. M.; Townsend, R. H. D.; Bjorkman, J. E.

    2013-03-20

    Some massive stars possess strong magnetic fields that confine plasma in the circumstellar environment. These magnetospheres have been studied spectroscopically, photometrically, and, more recently, interferometrically. Here we report on the first firm detection of a magnetosphere in continuum linear polarization, as a result of monitoring {sigma} Ori E at the Pico dos Dias Observatory. The non-zero intrinsic polarization indicates an asymmetric structure whose minor elongation axis is oriented 150. Degree-Sign 0 east of the celestial north. A modulation of the polarization was observed with a period of half of the rotation period, which supports the theoretical prediction of the presence of two diametrally opposed, corotating blobs of gas. A phase lag of -0.085 was detected between the polarization minimum and the primary minimum of the light curve, suggestive of a complex shape of the plasma clouds. We present a preliminary analysis of the data with the Rigidly Rotating Magnetosphere model, which could not reproduce simultaneously the photometric and polarimetric data. A toy model comprising two spherical corotating blobs joined by a thin disk proved more successful in reproducing the polarization modulation. With this model we were able to determine that the total scattering mass of the thin disk is similar to the mass of the blobs (2M{sub b}/M{sub d} = 1.2) and that the blobs are rotating counterclockwise on the plane of the sky. This result shows that polarimetry can provide a diagnostic of the geometry of clouds, which will serve as an important constraint for improving the Rigidly Rotating Magnetosphere model.

  13. Epitope mapping and functional analysis of sigma A and sigma NS proteins of avian reovirus

    SciTech Connect

    Huang, Pi H.; Li, Ying J.; Su, Yu P.; Lee, Long H.; Liu, Hung J. . E-mail: hjliu@mail.npust.edu.tw

    2005-02-20

    We have previously shown that avian reovirus (ARV) {sigma}A and {sigma}NS proteins possess dsRNA and ssRNA binding activity and suggested that there are two epitopes on {sigma}A (I and II) and three epitopes (A, B, and C) on {sigma}NS. To further define the location of epitopes on {sigma}A and {sigma}NS proteins and to further elucidate the biological functions of these epitopes by using monoclonal antibodies (MAbs) 62, 1F9, H1E1, and 4A123 against the ARV S1133 strain, the full-length and deletion fragments of S2 and S4 genes of ARV generated by polymerase chain reaction (PCR) were cloned into pET32 expression vectors and the fusion proteins were overexpressed in Escherichia coli BL21 strain. Epitope mapping using MAbs and E. coli-expressed deletion fragments of {sigma}A and {sigma}NS of the ARV S1133 strain, synthetic peptides, and the cross reactivity of MAbs to heterologous ARV strains demonstrated that epitope II on {sigma}A was located at amino acid residues {sup 340}QWVMAGLVSAA{sup 350} and epitope B on {sigma}NS at amino acid residues {sup 180}MLDMVDGRP{sup 188}. The MAbs (62, 1F9, and H1E1) directed against epitopes II and B did not require the native conformation of {sigma}A and {sigma}NS, suggesting that their binding activities were conformation-independent. On the other hand, MAb 4A123 only reacted with complete {sigma}NS but not with truncated {sigma}NS fusion proteins in Western blot, suggesting that the binding activity of MAb to epitope A on {sigma}NS was conformation-dependent. Amino acid sequence analysis and the binding assays of MAb 62 to heterologous ARV strains suggested that epitope II on {sigma}A was highly conserved among ARV strains and that this epitope is suitable as a serological marker for the detection of ARV antibodies following natural infection in chickens. On the contrary, an amino acid substitution at position 183 (M to V) in epitope B of ARV could hinder the reactivity of the {sigma}NS with MAb 1F9. The {sigma}NS of ARV with ss

  14. THE DEPENDENCE OF STAR FORMATION EFFICIENCY ON GAS SURFACE DENSITY

    SciTech Connect

    Burkert, Andreas; Hartmann, Lee E-mail: lhartm@umich.edu

    2013-08-10

    Studies by Lada et al. and Heiderman et al. have suggested that star formation mostly occurs above a threshold in gas surface density {Sigma} of {Sigma}{sub c} {approx} 120 M{sub Sun} pc{sup -2} (A{sub K} {approx} 0.8). Heiderman et al. infer a threshold by combining low-mass star-forming regions, which show a steep increase in the star formation rate per unit area {Sigma}{sub SFR} with increasing {Sigma}, and massive cores forming luminous stars which show a linear relation. We argue that these observations do not require a particular density threshold. The steep dependence of {Sigma}{sub SFR}, approaching unity at protostellar core densities, is a natural result of the increasing importance of self-gravity at high densities along with the corresponding decrease in evolutionary timescales. The linear behavior of {Sigma}{sub SFR} versus {Sigma} in massive cores is consistent with probing dense gas in gravitational collapse, forming stars at a characteristic free-fall timescale given by the use of a particular molecular tracer. The low-mass and high-mass regions show different correlations between gas surface density and the area A spanned at that density, with A {approx} {Sigma}{sup -3} for low-mass regions and A {approx} {Sigma}{sup -1} for the massive cores; this difference, along with the use of differing techniques to measure gas surface density and star formation, suggests that connecting the low-mass regions with massive cores is problematic. We show that the approximately linear relationship between dense gas mass and stellar mass used by Lada et al. similarly does not demand a particular threshold for star formation and requires continuing formation of dense gas. Our results are consistent with molecular clouds forming by galactic hydrodynamic flows with subsequent gravitational collapse.

  15. Involvement of sigma (sigma) receptors in the acute actions of methamphetamine: receptor binding and behavioral studies.

    PubMed

    Nguyen, Emily C; McCracken, Kari A; Liu, Yun; Pouw, Buddy; Matsumoto, Rae R

    2005-10-01

    Methamphetamine interacts with sigma (sigma) receptors, suggesting that the drug produces some of its physiological and behavioral effects through these sites. Therefore, in the present report, receptor binding and pharmacological studies were performed to characterize the interaction between methamphetamine and sigma receptors. Of the two major sigma receptor subtypes, sigma1 and sigma2, competition binding studies showed that methamphetamine has a 22-fold preferential affinity for the sigma1 subtype. Saturation binding studies using the sigma1 selective radioligand [3H]+-pentazocine showed that in the presence of methamphetamine, there was a significant change in Kd, but not Bmax, suggesting competitive interactions. In behavioral studies, pretreatment of Swiss Webster mice with the sigma1 receptor antagonists, BD1063 or BD1047, significantly attenuated the locomotor stimulatory effects of methamphetamine. Mice that were administered an antisense oligodeoxynucleotide to down-regulate brain sigma1 receptors also exhibited a reduced locomotor stimulatory response to methamphetamine, as compared to control mice receiving mismatch oligonucleotides. Together, the data suggest that sigma1 receptors are involved in the acute actions of methamphetamine and that antagonism of this subtype is sufficient to prevent the locomotor stimulatory effects of methamphetamine. PMID:15939443

  16. Search for Sigma--Delta hypernuclear conversion

    NASA Astrophysics Data System (ADS)

    Bukhari, Masroor Hassan Haider Shah

    This research was aimed at the study of the in-flight A=3 (K- , pi+/-) reactions leading to in situ nuclear formation of a Sigma hyperon, its interactions with nucleons, and subsequent conversion into a Λ hyperon. The analysis was based upon the data from the Brookhaven National Laboratory experiment E774 carried out at the Alternating Gradient Synchrotron. This experiment comprised a two-layered scintillation counting barrel detector and two spectrometers to detect the missing mass in the reaction on a 3He target, resulting in the Sigma hypernucleus formation. A Monte Carlo simulation of the experiment was written within the framework of the GEANT simulation tool, incorporating physics generators for all the involved channels and the technique of multiplicity tagging. The objective was to obtain and analyze the relevant multiplicities of the involved channels which could result from the primary reaction. Analysis of results from simulations and their comparison with the experimental data revealed insight into the interactions of a Sigma within the nucleus and helped identify the multiplicities which corresponded to the true Sigma-Λ conversion events. On the basis of this analysis, the three-body system SigmaNN in the s-shell and the SigmaN → ΛN conversion were investigated. In the second phase of this study, a theoretical model for the calculation of scattering parameters and relative cross section for (Sigma-.2 H) production leading to Sigma-Λ conversion was developed. This was based on the effective range expansion and a plane wave impulse approximation (PWIA) paradigm. Both the scattering and absorption amplitudes, corresponding to s-wave SigmaSigma and SigmaΛ scattering states, respectively, were calculated. Finally the parameters (and corresponding cross section) were extracted by fitting the simulated model to the experiment data. The nature of the obtained parameters and shape of the cross section shed significant light on the Sigma-Λ conversion

  17. Confirmation of the sigma meson

    SciTech Connect

    Toernqvist, N.A.; Roos, M.

    1996-03-01

    A very general model and an analysis of data on the lightest 0{sup ++} meson nonet shows that the {ital f}{sub 0}(980) and {ital f}{sub 0}(1300) resonance poles are two manifestations of the same {bar {ital ss}} state. On the other hand, the {bar {ital uu}}+{bar {ital dd}} state, when unitarized and strongly distorted by hadronic mass shifts, becomes an extremely broad (880 MeV) and light (860 MeV) resonance, with its pole at {ital s}=0.158{minus}{ital i}0.235 GeV{sup 2}. This is the {sigma} meson required by models for spontaneous breaking of chiral symmetry. It has been named the Higgs meson of QCD, because it generates most of the light hadron masses. It dominates {pi}{pi} scattering below 900 MeV and it is also the resonance required by nuclear physics. {copyright} {ital 1996 The American Physical Society.}

  18. SIGMA WEB INTERFACE FOR REACTOR DATA APPLICATIONS

    SciTech Connect

    Pritychenko,B.; Sonzogni, A.A.

    2010-05-09

    We present Sigma Web interface which provides user-friendly access for online analysis and plotting of the evaluated and experimental nuclear reaction data stored in the ENDF-6 and EXFOR formats. The interface includes advanced browsing and search capabilities, interactive plots of cross sections, angular distributions and spectra, nubars, comparisons between evaluated and experimental data, computations for cross section data sets, pre-calculated integral quantities, neutron cross section uncertainties plots and visualization of covariance matrices. Sigma is publicly available at the National Nuclear Data Center website at http://www.nndc.bnl.gov/sigma.

  19. Pharmacological and autoradiographic characterization of sigma receptors

    SciTech Connect

    Largent, B.L.

    1986-01-01

    The existence of three types of opioid receptors - ..mu.., kappa, and sigma - was postulated to explain the effects of different opioids in the chronic spinal dog. Sigma receptors, named for the prototypic agonist SKF 10,047 (N-allylnormetazocine), were suggested to mediate the psychotomimetic-like effects of SKF 10,047 in the dog. 3-(3-Hydroxyphenyl)-N-(1-propyl)piperidine (3-PPP) has been proposed as a selective dopamine autoreceptor agonist. However, the drug specificity of (+)(/sup 3/H)3-PPP binding in brain is identical to that of sigma receptor binding sites which may mediate psychotomimetic effects of some opioids. Pharmacological and autoradiographic analyses reveal that (+)(/sup 3/H)SKF 10,047, the prototypic sigma agonist, labels two sites in brain. The drug specificity of the high affinity site for (+)(/sup 3/H)SKF 10,047 resembles that of putative sigma receptors labeled with (+)(/sup 3/H)3-PPP, being potently inhibited by (+)3-PPP, haloperidol, and (+/-)pentazocine, and demonstrating stereoselectivity for the (+) isomer of SKF 10,047. Autoradiographic localizations of high affinity (+)(/sup 3/H)SKF 10,047 binding sites closely resemble those of (+)(/sup 3/H)3-PPP labeled sites with high levels of binding in the hippocampal pyramidal cell layer, hypothalamus, and pontine and cranial nerve nuclei. Thus, putative sigma receptors and PCP receptors represent distinct receptor populations in brain. This proposal is supported by the presence of sigma binding sites - and absence of PCP receptors - on NCB-20 cell membranes, a hybrid neurotumor cell line that provides a model system for the physiological and biochemical study of sigma receptors.

  20. Inclusive Sigma- photoproduction on the neutron via the reaction gamma n (p) ---> K+ Sigma- (p)

    SciTech Connect

    Jorn Langheinrich; Ana Lima; Barry Berman

    2006-06-01

    The analysis described here is part of a comprehensive survey of the elementary strangeness photoproduction cross sections on the nucleon. The six elementary strangeness reactions are {gamma}n {yields} K{sup 0}{Lambda} and {gamma}p {yields} K{sup +}{Lambda} {gamma}n {yields} K{sup 0}{Sigma}{sup 0} and {gamma}p {yields} K{sup +}{Sigma}{sup 0} {gamma}n {yields} K{sup +}{Sigma}{sup -} and {gamma}p {yields} K{sup 0}{Sigma}|{sup +}

  1. A TEST OF STAR FORMATION LAWS IN DISK GALAXIES

    SciTech Connect

    Tan, Jonathan C.

    2010-02-10

    We use observations of the radial profiles of the mass surface density of total, {sigma} {sub g}, and molecular, {sigma}{sub H2}, gas rotation velocity and star formation rate surface density, {sigma}{sub sfr}, of the molecular dominated regions of 12 disk galaxies from Leroy et al. to test several star formation laws: a 'Kennicutt-Schmidt power law', {sigma}{sub sfr} = A{sub g} {sigma}{sup 1.5} {sub g,2}; a 'constant molecular law', {sigma}{sub sfr} = A {sub H2}{sigma}{sub H2,2}; the 'turbulence-regulated laws' of Krumholz and McKee (KM) and Krumholz, McKee, and Tumlinson (KMT), a 'gas-{omega} law', {sigma}{sub sfr} = B {sub {omega}}{sigma} {sub g}{omega}; and a shear-driven 'giant molecular cloud (GMC) collisions law', {sigma}{sub sfr} = B {sub CC}{sigma} {sub g}{omega}(1 - 0.7{beta}), where {beta} {identical_to} d ln v {sub circ}/d ln r. We find the constant molecular law, KMT turbulence law, and GMC collision law are the most accurate, with an rms error of a factor of 1.5 if the normalization constants are allowed to vary between galaxies. Of these three laws, the GMC collision law does not require a change in physics to account for the full range of star formation activity seen from normal galaxies to circumnuclear starbursts. A single global GMC collision law with B {sub CC} = 8.0 x 10{sup -3}, i.e., a gas consumption time of 20 orbital times for {beta} = 0, yields an rms error of a factor of 1.8.

  2. GAS SURFACE DENSITY, STAR FORMATION RATE SURFACE DENSITY, AND THE MAXIMUM MASS OF YOUNG STAR CLUSTERS IN A DISK GALAXY. I. THE FLOCCULENT GALAXY M 33

    SciTech Connect

    Gonzalez-Lopezlira, Rosa A.; Pflamm-Altenburg, Jan; Kroupa, Pavel

    2012-12-20

    We analyze the relationship between maximum cluster mass M{sub max} and surface densities of total gas ({Sigma}{sub gas}), molecular gas ({Sigma}{sub H{sub 2}}), and star formation rate ({Sigma}{sub SFR}) in the flocculent galaxy M 33, using published gas data and a catalog of more than 600 young star clusters in its disk. By comparing the radial distributions of gas and most massive cluster masses, we find that M{sub max}{proportional_to}{Sigma}{sup 4.7{+-}0.4}{sub gas}, M{sub max}{proportional_to}{Sigma}{sup 1.3{+-}0.1}{sub H{sub 2}}, and M{sub max}{proportional_to}{Sigma}{sup 1.0{+-}0.1}{sub SFR}. We rule out that these correlations result from the size of the sample; hence, the change of the maximum cluster mass must be due to physical causes.

  3. Six Lessons We Learned Applying Six Sigma

    NASA Technical Reports Server (NTRS)

    Carroll, Napoleon; Casleton, Christa H.

    2005-01-01

    As Chief Financial Officer of Kennedy Space Center (KSC), I'm not only responsible for financial planning and accounting but also for building strong partnerships with the CFO customers, who include Space Shuttle and International Space Station operations as well all who manage the KSC Spaceport. My never ending goal is to design, manage and continuously improve our core business processes so that they deliver world class products and services to the CFO's customers. I became interested in Six Sigma as Christa Casleton (KSC's first Six Sigma Black belt) applied Six Sigma tools and methods to our Plan and Account for Travel Costs Process. Her analysis was fresh, innovative and thorough but, even more impressive, was her approach to ensure ongoing, continuous process improvement. Encouraged by the results, I launched two more process improvement initiatives aimed at applying Six Sigma principles to CFO processes that not only touch most of my employees but also have direct customer impact. As many of you know, Six Sigma is a measurement scale that compares the output of a process with customer requirements. That's straight forward, but demands that you not only understand your processes but also know your products and the critical customer requirements. The objective is to isolate and eliminate the causes of process variation so that the customer sees consistently high quality.

  4. FOURIER TRANSFORM EMISSION SPECTROSCOPY OF THE B {sup 2}{Sigma}{sup +}-X {sup 2}{Sigma}{sup +} (VIOLET) SYSTEM OF {sup 13}C{sup 14}N

    SciTech Connect

    Ram, R. S.; Bernath, P. F.

    2011-06-01

    Emission spectra of the B {sup 2}{Sigma}{sup +}-X {sup 2}{Sigma}{sup +} transition of {sup 13}C{sup 14}N have been observed at high resolution using the Fourier transform spectrometer associated with the McMath-Pierce Solar Telescope of the National Solar Observatory. The spectra have been measured in the 21000-30000 cm{sup -1} region and a total of 52 vibrational bands involving vibrational levels up to v = 15 of the ground and excited states have been rotationally analyzed to provide a much improved set of spectroscopic constants. An experimental line list and calculated term values are provided. The results of the present analysis should prove useful in the identification of additional {sup 13}C{sup 14}N lines in comets and cool stars, and will help in the determination of the {sup 12}C/{sup 13}C abundance ratio.

  5. All optical binary delta-sigma modulator

    NASA Astrophysics Data System (ADS)

    Sayeh, Mohammad R.; Siahmakoun, Azad

    2005-09-01

    This paper describes a novel A/D converter called "Binary Delta-Sigma Modulator" (BDSM) which operates only with nonnegative signal with positive feedback and binary threshold. This important modification to the conventional delta-sigma modulator makes the high-speed (>100GHz) all-optical implementation possible. It has also the capability to modify its own sampling frequency as well as its input dynamic range. This adaptive feature helps designers to optimize the system performance under highly noisy environment and also manage the power consumption of the A/D converters.

  6. A Lean Six Sigma journey in radiology.

    PubMed

    Bucci, Ronald V; Musitano, Anne

    2011-01-01

    The department of radiology at Akron Children's Hospital embarked on a Lean Six Sigma mission as part of a hospital wide initiative to show increased customer satisfaction, reduce employee dissatisfaction and frustration, and decrease costs. Three processes that were addressed were reducing the MRI scheduling back-log, reconciling discrepancies in billing radiology procedures, and implementing a daily management system. Keys to success is that managers provide opportunities to openly communicate between department sections to break down barriers. Executive leaders must be engaged in Lean Six Sigma for the company to be successful.

  7. A K3 sigma model with : symmetry

    NASA Astrophysics Data System (ADS)

    Gaberdiel, Matthias R.; Taormina, Anne; Volpato, Roberto; Wendland, Katrin

    2014-02-01

    The K3 sigma model based on the -orbifold of the D 4-torus theory is studied. It is shown that it has an equivalent description in terms of twelve free Majorana fermions, or as a rational conformal field theory based on the affine algebra . By combining these different viewpoints we show that the = (4 , 4) preserving symmetries of this theory are described by the discrete symmetry group : . This model therefore accounts for one of the largest maximal symmetry groups of K3 sigma models. The symmetry group involves also generators that, from the orbifold point of view, map untwisted and twisted sector states into one another.

  8. MAXIMALLY STAR-FORMING GALACTIC DISKS. I. STARBURST REGULATION VIA FEEDBACK-DRIVEN TURBULENCE

    SciTech Connect

    Ostriker, Eve C.; Shetty, Rahul E-mail: rshetty@ita.uni-heidelberg.de

    2011-04-10

    Star formation rates in the centers of disk galaxies often vastly exceed those at larger radii, whether measured by the surface density of star formation {Sigma}{sub SFR}, by the star formation rate per unit gas mass, {Sigma}{sub SFR}/{Sigma}, or even by total output. In this paper, we investigate the idea that central starbursts are self-regulated systems in which the momentum flux injected to the interstellar medium (ISM) by star formation balances the gravitational force confining the ISM gas in the disk. For most starbursts, supernovae are the largest contributor to the momentum flux, and turbulence provides the main pressure support for the predominantly molecular ISM. If the momentum feedback per stellar mass formed is p{sub *}/m{sub *} {approx} 3000 km s{sup -1}, the predicted star formation rate is {Sigma}{sub SFR} {approx} 2{pi}G{Sigma}{sup 2} m{sub *}/p{sub *} {approx} 0.1 M{sub sun} kpc{sup -2} yr{sup -1}({Sigma}/100 M{sub sun} pc{sup -2}){sup 2} in regions where gas dominates the vertical gravity. We compare this prediction with numerical simulations of vertically resolved disks that model star formation including feedback, finding good agreement for gas surface densities in the range {Sigma} {approx} 10{sup 2}-10{sup 3} M{sub sun} pc{sup -2}. We also compare to a compilation of star formation rates and gas contents from local and high-redshift galaxies (both mergers and normal galaxies), finding good agreement provided that the conversion factor X{sub CO} from integrated CO emission to H{sub 2} surface density decreases modestly as {Sigma} and {Sigma}{sub SFR} increase. Star formation rates in dense, turbulent gas are also expected to depend on the gravitational free-fall time at the corresponding mean ISM density {rho}{sub 0}; if the star formation efficiency per free-fall time is {epsilon}{sub ff}({rho}{sub 0}) {approx} 0.01, the turbulent velocity dispersion driven by feedback is expected to be v{sub z} = 0.4 {epsilon}{sub ff}({rho}{sub 0})p

  9. O-star kinematics

    SciTech Connect

    Karimova, D.K.; Pavlovskaya, E.D.

    1984-01-01

    Proper motions determined by the authors are utilized to study the kinematics of 79 O-type stars at distance r< or =2.5 kpc. The sample is divided into two groups, having space-velocity dispersions tau/sub I/roughly-equal10 km/sec, sigma/sub II/roughly-equal35 km/sec. Solutions for the velocity-field parameters for group I yield a galactic angular rotation speed ..omega../sub 0/ = 24.9 km sec/sup -1/ kpc/sup -1/ at the sun (for R/sub 0/ = 10.0 kpc) and an Oort constant A = 12.2 km sec/sup -1/ kpc/sup -1/. Most of the O stars exhibit a small z-velocity directed away from the galactic plane. The velocity-ellipsoid parameters and box-orbit elements are calculated.

  10. Interstellar absorption lines in the spectrum of sigma Sco using Copernicus observations

    NASA Technical Reports Server (NTRS)

    Allen, M. M.; Snow, T. P.

    1986-01-01

    Since the launch of Copernicus in 1972, studies have been made of the depletion of gas-phase elements onto dust grains. A few stars have been studied in detail, resulting in a standard depletion pattern which has since been used for comparison. Recent developments, however, have suggested that this standard pattern may need to be re-examined. Some weak, semi-forbidden lines were detected recently which may be able to resolve some of the ambiguities. Studies of single elements have shown that depletion of carbon and oxgyen are much smaller than previously determined. The high resolution ultraviolet spectral scans of sigma Sco were originally made in 1973, but have only recently been analyzed. All these stars are bright and moderately reddened. All four stars will be analyzed in detail, but sigma Sco is the first one completed. The data has broad coverage of ions, making these stars excellent candidates for determination of accurate depletions. A profile-fitting analysis was used rather than curves-of-growth in order to determine separate abundances and depletions in components separated by several km/sec.

  11. Electromagnetic interactions in the sigma-. omega. model

    SciTech Connect

    de Forest,Jr., T.

    1984-08-27

    The predictions of the sigma-..omega.. model for electromagnetic current are explored and found to be quite different from those given by the impulse approximation. In particular large variations in the quasielastic electron scattering cross section are found depending upon the choice of the operator used for the current.

  12. How Six Sigma Methodology Improved Doctors' Performance

    ERIC Educational Resources Information Center

    Zafiropoulos, George

    2015-01-01

    Six Sigma methodology was used in a District General Hospital to assess the effect of the introduction of an educational programme to limit unnecessary admissions. The performance of the doctors involved in the programme was assessed. Ishikawa Fishbone and 5 S's were initially used and Pareto analysis of their findings was performed. The results…

  13. Improving Learning Outcome Using Six Sigma Methodology

    ERIC Educational Resources Information Center

    Tetteh, Godson A.

    2015-01-01

    Purpose: The purpose of this research paper is to apply the Six Sigma methodology to identify the attributes of a lecturer that will help improve a student's prior knowledge of a discipline from an initial "x" per cent knowledge to a higher "y" per cent of knowledge. Design/methodology/approach: The data collection method…

  14. The science of Six Sigma in hospitals.

    PubMed

    Guinane, Carole S; Davis, Noreen H

    2004-01-01

    Six Sigma applied to hospital processes and services can lead to breakthrough improvements, near-perfect outcomes, and zero defects. It is wise to consider this aspect of quality science as part of an overall Total Quality Management program. Senior leadership support and involvement is critical to the success of this strategy.

  15. Do narrow {Sigma}-hypernuclear states exist?

    SciTech Connect

    Chrien, R.E.

    1995-12-31

    Reports of narrow states in {Sigma}-hypernucleus production have appeared from time to time. The present experiment is a repeat of the first and seemingly most definitive such experiment, that on a target of {sup 9}Be, but with much better statistics. No narrow states were observed.

  16. Need of Six Sigma in Education

    ERIC Educational Resources Information Center

    Mehrotra, Dheeraj

    2007-01-01

    The marching trend of the new economic order has generated a new capsule of SIX SIGMA as a unified approach to process excellence. The tests reveal that it has transformed some of the most successful companies in the world like Motorola, GE etc. It is activated as an approach to aiming at the target by changing the culture of a company, involving…

  17. Six Sigma and Introductory Statistics Education

    ERIC Educational Resources Information Center

    Maleyeff, John; Kaminsky, Frank C.

    2002-01-01

    A conflict exists between the way statistics is practiced in contemporary business environments and the way statistics is taught in schools of management. While businesses are embracing programs, such as six sigma and TQM, that bring statistical methods to the forefront of management decision making, students do not graduate with the skills to…

  18. THE STAR FORMATION LAWS OF EDDINGTON-LIMITED STAR-FORMING DISKS

    SciTech Connect

    Ballantyne, D. R.; Armour, J. N.; Indergaard, J.

    2013-03-10

    Two important avenues into understanding the formation and evolution of galaxies are the Kennicutt-Schmidt (K-S) and Elmegreen-Silk (E-S) laws. These relations connect the surface densities of gas and star formation ({Sigma}{sub gas} and {Sigma}-dot{sub *}, respectively) in a galaxy. To elucidate the K-S and E-S laws for disks where {Sigma}{sub gas} {approx}> 10{sup 4} M{sub Sun} pc{sup -2}, we compute 132 Eddington-limited star-forming disk models with radii spanning tens to hundreds of parsecs. The theoretically expected slopes ( Almost-Equal-To 1 for the K-S law and Almost-Equal-To 0.5 for the E-S relation) are relatively robust to spatial averaging over the disks. However, the star formation laws exhibit a strong dependence on opacity that separates the models by the dust-to-gas ratio that may lead to the appearance of a erroneously large slope. The total infrared luminosity (L{sub TIR}) and multiple carbon monoxide (CO) line intensities were computed for each model. While L{sub TIR} can yield an estimate of the average {Sigma}-dot{sub *} that is correct to within a factor of two, the velocity-integrated CO line intensity is a poor proxy for the average {Sigma}{sub gas} for these warm and dense disks, making the CO conversion factor ({alpha}{sub CO}) all but useless. Thus, observationally derived K-S and E-S laws at these values of {Sigma}{sub gas} that uses any transition of CO will provide a poor measurement of the underlying star formation relation. Studies of the star formation laws of Eddington-limited disks will require a high-J transition of a high density molecular tracer, as well as a sample of galaxies with known metallicity estimates.

  19. THE L-{sigma} RELATION OF LOCAL H II GALAXIES

    SciTech Connect

    Bordalo, V.; Telles, E. E-mail: etelles@on.br

    2011-07-01

    For the first time we present a new data set of emission line widths for 118 star-forming regions in H II galaxies (HIIGs). This homogeneous set is used to investigate the L-{sigma} relation in conjunction with optical spectrophotometric observations. We were able to classify their nebular emission line profiles due to our high-resolution spectra. Peculiarities in the line profiles such as sharp lines, wings, asymmetries, and in some cases more than one component in emission were verified. From a new independent homogeneous set of spectrophotometric data, we derived physical condition parameters and performed statistical principal component analysis. We have investigated the potential role of metallicity (O/H), H{beta} equivalent width (W{sub H{beta}}), and ionization ratio [O III]/[O II] to account for the observational scatter of the L-{sigma} relation. Our results indicate that the L-{sigma} relation for HIIGs is more sensitive to the evolution of the current starburst event (short-term evolution) and dated by W{sub H}{beta} or even the [O III]/[O II] ratio. The long-term evolution measured by O/H also plays a potential role in determining the luminosity of the current burst for a given velocity dispersion and age as previously suggested. Additionally, galaxies showing Gaussian line profiles present tighter correlations indicating that they are the best targets for the application of the parametric relations as an extragalactic cosmological distance indicator. Best fits for a restricted homogeneous sample of 45 HIIGs provide us with a set of new extragalactic distance indicators with an rms scatter compatible with observational errors of {delta}log L{sub H}{alpha} = 0.2 dex or 0.5 mag. Improvements may still come from future optimized observational programs to reduce the observational uncertainties on the predicted luminosities of HIIGs in order to achieve the precision required for the application of these relations as tests of cosmological models.

  20. Star Light, Star Bright.

    ERIC Educational Resources Information Center

    Iadevaia, David G.

    1984-01-01

    Presents a technique for obtaining a rough measure of the brightness among different stars. Materials needed include a standard 35-mm camera, a plastic ruler, and a photo enlarger. Although a telescope can be used, it is not essential. (JN)

  1. The sigma receptor: evolution of the concept in neuropsychopharmacology.

    PubMed

    Hayashi, T; Su, Tp

    2005-10-01

    Although originally proposed as a subtype of opioid receptors, the sigma receptor is now confirmed to be a non-opioid receptor that binds diverse classes of psychotropic drugs. Sigma receptors are subdivided into two subtypes, sigma-1 and sigma-2. The sigma-1 receptor is a 25-kDa protein possessing one putative transmembrane domain and an endoplasmic reticulum retention signal. Sigma-1 receptors are highly expressed in deeper laminae of the cortex, olfactory bulb, nuclei of mesencephalon, hypothalamus, and Purkinje cells in the brain. Sigma-1 receptors are predominantly localized at the endoplasmic reticulum of both neurons and oligodendrocytes. From behavioral studies, sigma-1 receptors were shown to be involved in higher-ordered brain functions including memory and drug dependence. The actions mediated by sigma-1 receptors at the cellular level can be considered either as acute or chronic. The acute actions include the modulation of ion channels (i.e., K+ channel, NMDA receptors, IP3 receptors) and the sigma-1 receptor translocation. Chronic actions of sigma-1 receptors are basically considered to be the result of an up- or down regulation of the sigma-1 receptor itself. For example, the upregulation of sigma-1 receptors per se, even without exogenous ligands, promotes cellular differentiation and reconstitution of lipid microdomains (lipid rafts) in cultured cells. These findings together suggest that sigma-1 receptors might possess a constitutive biological activity, and that sigma-1 receptor ligands might merely work as modulators of the innate activity of this protein. Recent in vitro and in vitro studies strongly point to the possibility that sigma-1 receptors participate in membrane remodeling and cellular differentiation in the nervous system.

  2. Incorporating Six Sigma Methodology Training into Chemical Engineering Education

    ERIC Educational Resources Information Center

    Dai, Lenore L.

    2007-01-01

    Six Sigma is a buzz term in today's technology and business world and there has been increasing interest to initiate Six Sigma training in college education. We have successfully incorporated Six Sigma methodology training into a traditional chemical engineering course, Engineering Experimentation, at Texas Tech University. The students have…

  3. Operational excellence (six sigma) philosophy: Application to software quality assurance

    SciTech Connect

    Lackner, M.

    1997-11-01

    This report contains viewgraphs on operational excellence philosophy of six sigma applied to software quality assurance. This report outlines the following: goal of six sigma; six sigma tools; manufacturing vs administrative processes; Software quality assurance document inspections; map software quality assurance requirements document; failure mode effects analysis for requirements document; measuring the right response variables; and questions.

  4. Close encounters of the third-body kind. [intruding bodies in binary star systems

    NASA Technical Reports Server (NTRS)

    Davies, M. B.; Benz, W.; Hills, J. G.

    1994-01-01

    We simulated encounters involving binaries of two eccentricities: e = 0 (i.e., circular binaries) and e = 0.5. In both cases the binary contained a point mass of 1.4 solar masses (i.e., a neutron star) and a 0.8 solar masses main-sequence star modeled as a polytrope. The semimajor axes of both binaries were set to 60 solar radii (0.28 AU). We considered intruders of three masses: 1.4 solar masses (a neutron star), 0.8 solar masses (a main-sequence star or a higher mass white dwarf), and 0.64 solar masses (a more typical mass white dwarf). Our strategy was to perform a large number (40,000) of encounters using a three-body code, then to rerun a small number of cases with a three-dimensional smoothed particle hydrodynamics (SPH) code to determine the importance of hydrodynamical effects. Using the results of the three-body runs, we computed the exchange across sections, sigma(sub ex). From the results of the SPH runs, we computed the cross sections for clean exchange, denoted by sigma(sub cx); the formation of a triple system, denoted by sigma(sub trp); and the formation of a merged binary with an object formed from the merger of two of the stars left in orbit around the third star, denoted by sigma(sub mb). For encounters between either binary and a 1.4 solar masses neutron star, sigma(sub cx) approx. 0.7 sigma(sub ex) and sigma(sub mb) + sigma(sub trp) approx. 0.3 sigma(sub ex). For encounters between either binary and the 0.8 solar masses main-sequence star, sigma(sub cx) approx. 0.50 sigma(sub ex) and sigma(sub mb) + sigma(sub trp) approx. 1.0 sigma(sub ex). If the main sequence star is replaced by a main-sequence star of the same mass, we have sigma(sub cx) approx. 0.5 sigma(sub ex) and sigma(sub mb) + sigma(sub trp) approx. 1.6 sigma(sub ex). Although the exchange cross section is a sensitive function of intruder mass, we see that the cross section to produce merged binaries is roughly independent of intruder mass. The merged binaries produced have semi

  5. Non-compact nonlinear sigma models

    NASA Astrophysics Data System (ADS)

    de Rham, Claudia; Tolley, Andrew J.; Zhou, Shuang-Yong

    2016-09-01

    The target space of a nonlinear sigma model is usually required to be positive definite to avoid ghosts. We introduce a unique class of nonlinear sigma models where the target space metric has a Lorentzian signature, thus the associated group being non-compact. We show that the would-be ghost associated with the negative direction is fully projected out by 2 second-class constraints, and there exist stable solutions in this class of models. This result also has important implications for Lorentz-invariant massive gravity: There exist stable nontrivial vacua in massive gravity that are free from any linear vDVZ-discontinuity and a Λ2 decoupling limit can be defined on these vacua.

  6. Quantization of the nonlinear sigma model revisited

    NASA Astrophysics Data System (ADS)

    Nguyen, Timothy

    2016-08-01

    We revisit the subject of perturbatively quantizing the nonlinear sigma model in two dimensions from a rigorous, mathematical point of view. Our main contribution is to make precise the cohomological problem of eliminating potential anomalies that may arise when trying to preserve symmetries under quantization. The symmetries we consider are twofold: (i) diffeomorphism covariance for a general target manifold; (ii) a transitive group of isometries when the target manifold is a homogeneous space. We show that there are no anomalies in case (i) and that (ii) is also anomaly-free under additional assumptions on the target homogeneous space, in agreement with the work of Friedan. We carry out some explicit computations for the O(N)-model. Finally, we show how a suitable notion of the renormalization group establishes the Ricci flow as the one loop renormalization group flow of the nonlinear sigma model.

  7. Phantom black holes and sigma models

    SciTech Connect

    Azreg-Aienou, Mustapha; Clement, Gerard; Fabris, Julio C.; Rodrigues, Manuel E.

    2011-06-15

    We construct static multicenter solutions of phantom Einstein-Maxwell-dilaton theory from null geodesics of the target space, leading to regular black holes without spatial symmetry for certain discrete values of the dilaton coupling constant. We also discuss the three-dimensional gravitating sigma models obtained by reduction of phantom Einstein-Maxwell, phantom Kaluza-Klein and phantom Einstein-Maxwell-dilaton-axion theories. In each case, we generate by group transformations phantom charged black hole solutions from a neutral seed.

  8. Strangeness and meson-nucleon sigma terms

    SciTech Connect

    Dahiya, Harleen; Sharma, Neetika

    2011-10-21

    The chiral constituent quark model ({chi}CQM) has been extended to calculate the flavor structure of the nucleon through the meson-nucleon sigma terms which have large contributions from the quark sea and are greatly affected by chiral symmetry breaking and SU(3) symmetry breaking. The hidden strangeness component in the nucleon has also been investigated and its significant contribution is found to be consistent with the recent available experimental observations.

  9. NEW ISOLATED PLANETARY-MASS OBJECTS AND THE STELLAR AND SUBSTELLAR MASS FUNCTION OF THE {sigma} ORIONIS CLUSTER

    SciTech Connect

    Pena Ramirez, K.; Bejar, V. J. S.; Petr-Gotzens, M. G. E-mail: vbejar@iac.es E-mail: ege@cab.inta-csic.es

    2012-07-20

    We report on our analysis of the VISTA Orion ZY JHK{sub s} photometric data (completeness magnitudes of Z = 22.6 and J = 21.0 mag) focusing on a circular area of 2798.4 arcmin{sup 2} around the young {sigma} Orionis star cluster ({approx}3 Myr, {approx}352 pc, and solar metallicity). The combination of the VISTA photometry with optical, WISE and Spitzer data allows us to identify a total of 210 {sigma} Orionis member candidates with masses in the interval 0.25-0.004 M{sub Sun }, 23 of which are new planetary-mass object findings. These discoveries double the number of cluster planetary-mass candidates known so far. One object has colors compatible with a T spectral type. The {sigma} Orionis cluster harbors about as many brown dwarfs (69, 0.072-0.012 M{sub Sun }) and planetary-mass objects (37, 0.012-0.004 M{sub Sun }) as very low mass stars (104, 0.25-0.072 M{sub Sun }). Based on Spitzer data, we derive a disk frequency of {approx}40% for very low mass stars, brown dwarfs, and planetary-mass objects in {sigma} Orionis. The radial density distributions of these three mass intervals are alike: all are spatially concentrated within an effective radius of 12' (1.2 pc) around the multiple star {sigma} Ori, and no obvious segregation between disk-bearing and diskless objects is observed. Using the VISTA data and the Mayrit catalog, we derive the cluster mass spectrum ({Delta}N/{Delta}M {approx} M{sup -{alpha}}) from {approx}19 to 0.006 M{sub Sun} (VISTA ZJ completeness), which is reasonably described by two power-law expressions with indices of {alpha} = 1.7 {+-} 0.2 for M > 0.35 M{sub Sun }, and {alpha} = 0.6 {+-} 0.2 for M < 0.35 M{sub Sun }. The {sigma} Orionis mass spectrum smoothly extends into the planetary-mass regime down to 0.004 M{sub Sun }. Our findings of T-type sources (<0.004 M{sub Sun }) in the VISTA {sigma} Orionis exploration appear to be smaller than what is predicted by the extrapolation of the cluster mass spectrum down to the survey J

  10. An extra-cytoplasmic function sigma factor and anti-sigma factor control carotenoid biosynthesis in Azospirillum brasilense.

    PubMed

    Thirunavukkarasu, Nagarajan; Mishra, Mukti Nath; Spaepen, Stijn; Vanderleyden, Jos; Gross, Carol A; Tripathi, Anil K

    2008-07-01

    Strains Sp7 and Cd of Azospirillum brasilense, a plant growth-promoting rhizobacterium, differ in synthesis of carotenoids. While colonies of strain Sp7 have a white-cream colour on plates, colonies of strain Cd are orange-pink coloured because of the synthesis of carotenoids. Screening of a mini-Tn5 mutant library of A. brasilense Sp7 revealed two orange-pink-coloured mutants that produced carotenoids. Cloning and sequencing of the Tn5 flanking region in both the carotenoid-producing mutants of Sp7 revealed insertion of Tn5 in an ORF encoding anti-sigma factor, a ChrR-like protein. The upstream region of the Tn5-mutated ORF contained another ORF that encoded an extra-cytoplasmic function (ECF)-class sigma factor (sigma(E), RpoE). When the nucleotide sequences of the corresponding ORFs from the carotenoid-producing strain Cd were analysed, the sequence of the Cd sigma(E) was identical to that of the carotenoid non-producing strain Sp7, but the Cd anti-sigma(E) ORF had a deletion that caused frame shifting and creation of a stop codon. This resulted in the premature termination of the protein, which was about 7 kDa smaller than the Sp7 anti-sigma(E). Cloning of Sp7 anti-sigma(E) in a broad-host-range expression vector and expression in A. brasilense Cd and in the anti-sigma(E) knockout mutant of A. brasilense Sp7 resulted in the inhibition of carotenoid synthesis. Similarly, cloning and overexpression of A. brasilense Sp7 sigma(E) in A. brasilense Sp7 resulted in the production of carotenoids. These observations clearly indicate that carotenoid synthesis in A. brasilense is controlled by sigma(E) with its cognate anti-sigma(E).

  11. Strange stars

    NASA Technical Reports Server (NTRS)

    Alcock, Charles; Farhi, Edward; Olinto, Angela

    1986-01-01

    Strange matter, a form of quark matter that is postulated to be absolute stable, may be the true ground stage of the hadrons. If this hypothesis is correct, neutron stars may convert to 'strange stars'. The mass-radius relation for strange stars is very different from that of neutron stars; there is no minimum mass, and for mass of 1 solar mass or less, mass is proportional to the cube of the radius. For masses between 1 solar mass and 2 solar masses, the radii of strange stars are about 10 km, as for neutron stars. Strange stars may have an exposed quark surface, which is capable of radiating at rates greatly exceeding the Eddington limit, but has a low emissivity for X-ray photons. The stars may have a thin crust with the same composition as the preneutron drip outer layer of a conventional neutron star crust. Strange stars cool efficiently via neutrino emission.

  12. Stars and Star Myths.

    ERIC Educational Resources Information Center

    Eason, Oliver

    Myths and tales from around the world about constellations and facts about stars in the constellations are presented. Most of the stories are from Greek and Roman mythology; however, a few Chinese, Japanese, Polynesian, Arabian, Jewish, and American Indian tales are also included. Following an introduction, myths are presented for the following 32…

  13. Sigma meson and lowest possible glueball candidate in an extended linear {sigma} model

    SciTech Connect

    Mukherjee, Tamal K.; Huang Mei; Yan Qishu

    2012-10-23

    We formulate an extended linear {sigma} model of a quarkonia nonet and a tetraquark nonet as well as a complex iso-singlet (glueball) field to study the low-lying scalar meson. Chiral symmetry and U{sub A}(1) symmetry and their breaking play important role to shape the scalar meson spectrum in our work. Based on our study we will comment on what may be the mass of the lowest possible scalar and pseudoscalar glueball states. We will also discuss on what may be the nature of the sigma or f{sub 0}(600) meson.

  14. Study ofe+e- to Lambda anti-Lambda, Lambda anti-Sigma^0,Sigma^0 anti-Sigma^0 using Initial State Radiation with BaBar

    SciTech Connect

    Aubert, B.

    2007-09-14

    We study the e+e- --> Lambda anti-Lambda gamma, Lambda anti-Sigma0 gamma, Sigma0 anti-Sigma0 gamma processes using 230 fb-1 of integrated luminosity collected by the BaBar detector at e+e- center-of-mass energy of 10.58 GeV. From the analysis of the baryon-antibaryon mass spectra the cross sections for e+e- --> Lambda anti-Lambda, Lambda anti-Sigma0, Sigma0 anti-Sigma0 are measured in the dibaryon mass range from threshold up to 3 GeV/c{sup 2}. The ratio of electric and magnetic form factors, |G{sub E}/G{sub M}|, is measured for e+e- --> Lambda anti-Lambda, and limits on the relative phase between Lambda form factors are obtained. We also measure the J/psi --> Lambda anti-Lambda, Sigma0 anti-Sigma0 and psi(2S) --> Lambda anti-Lambda branching fractions.

  15. Where Is the Sigma_{b}?

    NASA Astrophysics Data System (ADS)

    Itoh, C.; Minamikawa, T.; Miura, K.; Watanabe, T.

    1992-03-01

    The masses of s-wave bottom baryons are discussed in a semirelativistic quark model, on the basis of a quark-distance relation. We stress that the Sigma_{b} is heavier than Xi('}_{b) (b[su], b[sd]) containing the antisymmetric su(or sd) subsystem. We conclude that the two candidates for Lambda_{b} with very different masses are different states; Basile et al.'s result 5425(+175}_{-75) MeV is Lambda_{b}(b[du]), but Arenton et al.'s result ~ 5750 MeV is Xi('0}_{b) (b[su]).

  16. Pulsating Stars

    NASA Astrophysics Data System (ADS)

    Catelan, M.; Smith, H. A.

    2015-03-01

    This book surveys our understanding of stars which change in brightness because they pulsate. Pulsating variable stars are keys to distance scales inside and beyond the Milky Way galaxy. They test our understanding not only of stellar pulsation theory but also of stellar structure and evolution theory. Moreover, pulsating stars are important probes of the formation and evolution of our own and neighboring galaxies. Our understanding of pulsating stars has greatly increased in recent years as large-scale surveys of pulsating stars in the Milky Way and other Local Group galaxies have provided a wealth of new observations and as space-based instruments have studied particular pulsating stars in unprecedented detail.

  17. Ionic rotational branching ratios in resonant enhanced multiphoton ionization of NO via the A2Sigma(+)(3s sigma) and D2Sigma(+)(3p sigma) states

    NASA Astrophysics Data System (ADS)

    Rudolph, H.; McKoy, V.; Dixit, S. N.; Huo, W. M.

    1988-01-01

    Results are presented for the rotationally resolved photoelectron spectra resulting from a (2 + 1) one-color resonant enhanced multiphoton ionization (REMPI) of NO via the rotationally clean S21(11.5) and mixed S11(15.5) + R21(15.5) branches of the 0-0 transition in the D-X band. The calculations were done in the fixed-nuclei frozen core approximation. The resulting photoionization spectra, convoluted with a Lorentzian detection function, agree qualitatively with experimental results of Viswanathan et al. (1986) and support their conclusion that the nonspherical nature of the molecular potential creates a substantial l-mixing in the continuum, which in turn leads to the intense Delta N = 0 peak. The rather strong photoelectron energy dependence of the rotational branching ratios of the D 2Sigma(+) S21(11.5) line was investigated and compared to the weak energy dependence of the A 2Sigma(+) R22(21.5) line.

  18. Machine Process Capability Information Through Six Sigma

    SciTech Connect

    Lackner, M.F.

    1998-03-13

    A project investigating details concerning machine process capability information and its accessibility has been conducted. The thesis of the project proposed designing a part (denoted as a machine capability workpiece) based on the major machining features of a given machine. Parts are machined and measured to gather representative production, short-term variation. The information is utilized to predict the expected defect rate, expressed in terms of a composite sigma level process capability index, for a production part. Presently, decisions concerning process planning, particularly what machine will statistically produce the minimum amount of defects based on machined features and associated tolerances, are rarely made. Six sigma tools and methodology were employed to conduct this investigation at AlliedSignal FM and T. Tools such as the thought process map, factor relationship diagrams, and components of variance were used. This study is progressing toward completion. This research study was an example of how machine process capability information may be gathered for milling planar faces (horizontal) and slot features. The planning method used to determine where and how to gather variation for the part to be designed is known as factor relationship diagramming. Components-of-variation is then applied to the gathered data to arrive at the contributing level of variation illustrated within the factor relationship diagram. The idea of using this capability information beyond process planning to the other business enterprise operations is proposed.

  19. Mucosal vaccination by adenoviruses displaying reovirus sigma 1

    SciTech Connect

    Weaver, Eric A.; Camacho, Zenaido T.; Hillestad, Matthew L.; Crosby, Catherine M.; Turner, Mallory A.; Guenzel, Adam J.; Fadel, Hind J.; Mercier, George T.; Barry, Michael A.

    2015-08-15

    We developed adenovirus serotype 5 (Ad5) vectors displaying the sigma 1 protein from reovirus as mucosal vaccines. Ad5-sigma retargets to JAM-1 and sialic acid, but has 40-fold reduced gene delivery when compared to Ad5. While weaker at transduction, Ad5-sigma generates stronger T cell responses than Ad5 when used for mucosal immunization. In this work, new Ad5-fiber-sigma vectors were generated by varying the number of fiber β-spiral shaft repeats (R) between the fiber tail and sigma. Increasing chimera length led to decreasing insertion of these proteinsAd5 virions. Ad-R3 and R14 vectors effectively targeted JAM-1 in vitro while R20 did not. When wereused to immunize mice by the intranasal route, Ad5-R3-sigma produced higher serum and vaginal antibody responses than Ad5. These data suggest optimized Ad-sigma vectors may be useful vectors for mucosal vaccination. - Highlights: • Constructed adenoviruses (Ads) displaying different reovirus sigma 1 fusion proteins. • Progressively longer chimeras were more poorly encapsidated onto Ad virions. • Ad5-R3-sigma mediated better systemic and mucosal immune responses than Ad5.

  20. STAR System.

    ERIC Educational Resources Information Center

    Doverspike, James E.

    The STAR System is a developmental guidance approach to be used with elementary school children in the 5th or 6th grades. Two basic purposes underlie STAR: to increase learning potential and to enhance personal growth and development. STAR refers to 4 basic skills: sensory, thinking, adapting, and revising. Major components of the 4 skills are:…

  1. Massive Stars

    NASA Astrophysics Data System (ADS)

    Livio, Mario; Villaver, Eva

    2009-11-01

    Participants; Preface Mario Livio and Eva Villaver; 1. High-mass star formation by gravitational collapse of massive cores M. R. Krumholz; 2. Observations of massive star formation N. A. Patel; 3. Massive star formation in the Galactic center D. F. Figer; 4. An X-ray tour of massive star-forming regions with Chandra L. K. Townsley; 5. Massive stars: feedback effects in the local universe M. S. Oey and C. J. Clarke; 6. The initial mass function in clusters B. G. Elmegreen; 7. Massive stars and star clusters in the Antennae galaxies B. C. Whitmore; 8. On the binarity of Eta Carinae T. R. Gull; 9. Parameters and winds of hot massive stars R. P. Kudritzki and M. A. Urbaneja; 10. Unraveling the Galaxy to find the first stars J. Tumlinson; 11. Optically observable zero-age main-sequence O stars N. R. Walborn; 12. Metallicity-dependent Wolf-Raynet winds P. A. Crowther; 13. Eruptive mass loss in very massive stars and Population III stars N. Smith; 14. From progenitor to afterlife R. A. Chevalier; 15. Pair-production supernovae: theory and observation E. Scannapieco; 16. Cosmic infrared background and Population III: an overview A. Kashlinsky.

  2. Characterization of pulmonary sigma receptors by radioligand binding.

    PubMed

    Lever, John R; Litton, Tyler P; Fergason-Cantrell, Emily A

    2015-09-01

    This study establishes the expression of appreciable populations of sites on mouse lung membranes that exhibit radioligand binding properties and pharmacology consistent with assignment as sigma1 and sigma2 receptors. Specific binding of the sigma1 receptor radioligand [(3)H](+)-pentazocine reached steady state within 6h at 37°C. Saturation studies revealed high affinity binding to a single class of sites (Kd 1.36±0.04nM; Bmax 967±11fmol/mg protein). Inhibition studies showed appropriate sigma1 receptor pharmacology, including higher affinity for (+)-N-allylnormetazocine with respect to the (-)-enantiomer, and positive allosteric modulation of dextromethorphan binding by phenytoin. Using [(3)H]1,3-di(2-tolyl)guanidine in the presence of (+)-pentazocine to assess sigma2 receptor binding, steady state was achieved within 2min at 25°C. Cold saturation studies revealed one high affinity, low capacity binding site (Kd 31.8±8.3nM; Bmax 921±228fmol/mg protein) that displayed sigma2 receptor pharmacology. A very low affinity, high capacity interaction also was observed that represents saturable, but not sigma receptor specific, binding. A panel of ligands showed rank order inhibition of radioligand binding appropriate for the sigma2 receptor, with ifenprodil displaying the highest apparent affinity. In vivo, dextromethorphan inhibited the specific binding of a radioiodinated sigma1 receptor ligand in lung with an ED50 of 1.2μmol/kg, a value near the recommended dosage for the drug as a cough suppressant. Overall, the present work provides a foundation for studies of drug interactions with pulmonary sigma1 and sigma2 receptors in vitro and in vivo.

  3. Identification of the Helicobacter pylori anti-sigma28 factor.

    PubMed

    Colland, F; Rain, J C; Gounon, P; Labigne, A; Legrain, P; De Reuse, H

    2001-07-01

    Flagellar motility is essential for colonization of the human gastric mucosa by Helicobacter pylori. The flagellar filament is composed of two subunits, FlaA and FlaB. Transcription of the genes encoding these proteins is controlled by the sigma28 and sigma54 factors of RNA polymerase respectively. The expression of flagellar genes is regulated, but no sigma28-specific effector was identified. It was also unclear whether H. pylori possessed a checkpoint for flagellar synthesis, and no gene encoding an anti-sigma28 factor, FlgM, could be identified by sequence similarity searches. To investigate the sigma28-dependent regulation, a new approach based on genomic data was used. Two-hybrid screening with the H. pylori proteins identified a protein of unknown function (HP1122) interacting with the sigma28 factor and defined the C-terminal part of HP1122 (residues 48-76) as the interaction domain. HP1122 interacts with region 4 of sigma28 and prevents its association with the beta-region of H. pylori RNA polymerase. Thus, HP1122 presented the characteristics of an anti-sigma28 factor. This was confirmed in H. pylori by RNA dot-blot hybridization and electron microscopy. The level of sigma28-dependent flaA transcription was higher in a HP1122-deficient strain and was decreased by the overproduction of HP1122. The overproduction of HP1122 also resulted in H. pylori cells with highly truncated flagella. These results demonstrate that HP1122 is the H. pylori anti-sigma28 factor, FlgM, a major regulator of flagellum assembly. Potential anti-sigma28 factors were identified in Campylobacter jejuni, Pseudomonas aeruginosa and Thermotoga maritima by sequence homology with the C-terminal region of HP1122.

  4. Characterization of pulmonary sigma receptors by radioligand binding

    PubMed Central

    Lever, John R.; Litton, Tyler P.; Fergason-Cantrell, Emily A.

    2015-01-01

    This study establishes the expression of appreciable populations of sites on mouse lung membranes that exhibit radioligand binding properties and pharmacology consistent with assignment as sigma1 and sigma2 receptors. Specific binding of the sigma1 receptor radioligand [3H](+)-pentazocine reached steady state within 6 h at 37 °C. Saturation studies revealed high affinity binding to a single class of sites (Kd 1.36 ± 0.04 nM; Bmax 967 ± 11 fmol / mg protein). Inhibition studies showed appropriate sigma1 receptor pharmacology, including higher affinity for (+)-N-allylnormetazocine with respect to the (−)-enantiomer, and positive allosteric modulation of dextromethorphan binding by phenytoin. Using [3H]1,3-di(2-tolyl)guanidine in the presence of (+)-pentazocine to assess sigma2 receptor binding, steady state was achieved within 2 min at 25 °C. Cold saturation studies revealed one high affinity, low capacity binding site (Kd 31.8 ± 8.3 nM; Bmax 921 ± 228 fmol / mg protein) that displayed sigma2 receptor pharmacology. A very low affinity, high capacity interaction also was observed that represents saturable, but not sigma receptor specific, binding. A panel of ligands showed rank order inhibition of radioligand binding appropriate for the sigma2 receptor, with ifenprodil displaying the highest apparent affinity. In vivo, dextromethorphan inhibited the specific binding of a radioiodinated sigma1 receptor ligand in lung with an ED50 of 1.2 µmol / kg, a value near the recommended dosage for the drug as a cough suppressant. Overall, the present work provides a foundation for studies of drug interactions with pulmonary sigma1 and sigma2 receptors in vitro and in vivo. PMID:26004528

  5. Characterization of pulmonary sigma receptors by radioligand binding.

    PubMed

    Lever, John R; Litton, Tyler P; Fergason-Cantrell, Emily A

    2015-09-01

    This study establishes the expression of appreciable populations of sites on mouse lung membranes that exhibit radioligand binding properties and pharmacology consistent with assignment as sigma1 and sigma2 receptors. Specific binding of the sigma1 receptor radioligand [(3)H](+)-pentazocine reached steady state within 6h at 37°C. Saturation studies revealed high affinity binding to a single class of sites (Kd 1.36±0.04nM; Bmax 967±11fmol/mg protein). Inhibition studies showed appropriate sigma1 receptor pharmacology, including higher affinity for (+)-N-allylnormetazocine with respect to the (-)-enantiomer, and positive allosteric modulation of dextromethorphan binding by phenytoin. Using [(3)H]1,3-di(2-tolyl)guanidine in the presence of (+)-pentazocine to assess sigma2 receptor binding, steady state was achieved within 2min at 25°C. Cold saturation studies revealed one high affinity, low capacity binding site (Kd 31.8±8.3nM; Bmax 921±228fmol/mg protein) that displayed sigma2 receptor pharmacology. A very low affinity, high capacity interaction also was observed that represents saturable, but not sigma receptor specific, binding. A panel of ligands showed rank order inhibition of radioligand binding appropriate for the sigma2 receptor, with ifenprodil displaying the highest apparent affinity. In vivo, dextromethorphan inhibited the specific binding of a radioiodinated sigma1 receptor ligand in lung with an ED50 of 1.2μmol/kg, a value near the recommended dosage for the drug as a cough suppressant. Overall, the present work provides a foundation for studies of drug interactions with pulmonary sigma1 and sigma2 receptors in vitro and in vivo. PMID:26004528

  6. Hadron star models. [neutron stars

    NASA Technical Reports Server (NTRS)

    Cohen, J. M.; Boerner, G.

    1974-01-01

    The properties of fully relativistic rotating hadron star models are discussed using models based on recently developed equations of state. All of these stable neutron star models are bound with binding energies as high as about 25%. During hadron star formation, much of this energy will be released. The consequences, resulting from the release of this energy, are examined.

  7. Environmental Data Flow Six Sigma Process Improvement Savings Overview

    SciTech Connect

    Paige, Karen S

    2015-05-20

    An overview of the Environmental Data Flow Six Sigma improvement project covers LANL’s environmental data processing following receipt from the analytical laboratories. The Six Sigma project identified thirty-three process improvements, many of which focused on cutting costs or reducing the time it took to deliver data to clients.

  8. Application of Six Sigma Method to EMS Design

    NASA Astrophysics Data System (ADS)

    Rusko, Miroslav; Králiková, Ružena

    2011-01-01

    The Six Sigma method is a complex and flexible system of achieving, maintaining and maximizing the business success. Six Sigma is based mainly on understanding the customer needs and expectation, disciplined use of facts and statistics analysis, and responsible approach to managing, improving and establishing new business, manufacturing and service processes.

  9. Teaching Conversations with the XDS Sigma 7. System Users Manual.

    ERIC Educational Resources Information Center

    Mosmann, Charles; Bork, Alfred M.

    This manual is intended as a reference handbook for use in writing instructional dialogs on the Sigma-7 computer. The concern is to give concise information which one would need to write and debug dialogs on this system. Metasymbol, the macro-assembly program for the Sigma-7, is described. Definitions of terminology, legal forms descriptions of…

  10. delta. sigma/sub L//(pp) and jet physics

    SciTech Connect

    Richards, D.G.

    1988-01-01

    We show that there is a positive contribution to ..delta..sigma/sub L/(pp; s) = sigma /sub tot/(p(+)p(+); s) /minus/ sigma/sub tot/(p(+)p(/minus/); s) (where the +- refer to proton helicities) associated with the pointlike scattering of fundamental constituents. Simple arguments imply that this positive contribution would, at very high s, be larger in absolute value than the negative contribution to ..delta..sigma/sub L/ predicted from the exchange of the A/sub 1/ reggeon, and furthermore may provide important insight into the shape of the spin weighted quark and gluon distributions. Measurements of ..delta..sigma/sub L/ in the energy range ..sqrt..s = 18 /minus/ 30 GeV also should help clarify theoretical ideas associated with the observations of ''minijets'' and could aid in the prediction of event structure at future high energy colliders. 24 refs. 6 figs.

  11. FEEDBACK-REGULATED STAR FORMATION: IMPLICATIONS FOR THE KENNICUTT-SCHMIDT LAW

    SciTech Connect

    Dib, Sami

    2011-08-10

    We derive a metallicity-dependent relation between the surface density of the star formation rate ({Sigma}{sub SFR}) and the gas surface density ({Sigma}{sub g}) in a feedback-regulated model of star formation in galactic disks. In this model, star formation occurs in gravitationally bound protocluster clumps embedded in larger giant molecular clouds with the protocluster clump mass function following a power-law function with a slope of -2. Metallicity-dependent feedback is generated by the winds of OB stars (M {approx}> 5 M{sub sun}) that form in the clumps. The quenching of star formation in clumps of decreasing metallicity occurs at later epochs due to weaker wind luminosities, thus resulting in higher final star formation efficiencies (SFE{sub exp}). By combining SFE{sub exp} with the timescales on which gas expulsion occurs, we derive the metallicity-dependent SFR per unit time in this model as a function of {Sigma}{sub g}. This is combined with the molecular gas fraction in order to derive the global dependence of {Sigma}{sub SFR} on {Sigma}{sub g}. The model reproduces very well the observed star formation laws extending from low gas surface densities up to the starburst regime. Furthermore, our results show a dependence of {Sigma}{sub SFR} on metallicity over the entire range of gas surface densities in contrast to other models and can also explain part of the scatter in the observations. We provide a tabulated form of the star formation laws that can easily be incorporated into numerical simulations or semi-analytical models of galaxy formation and evolution.

  12. Automated system for measurement, collection and processing of hydrometeorological data aboard scientific research vessels of the GUGMS (SIGMA-s)

    NASA Technical Reports Server (NTRS)

    Borisenkov, Y. P.; Fedorov, O. M.

    1974-01-01

    A report is made on the automated system known as SIGMA-s for the measurement, collection, and processing of hydrometeorological data aboard scientific research vessels of the Hydrometeorological Service. The various components of the system and the interfacing between them are described, as well as the projects that the system is equipped to handle.

  13. Sporulation and primary sigma factor homologous genes in Clostridium acetobutylicum.

    PubMed Central

    Sauer, U; Treuner, A; Buchholz, M; Santangelo, J D; Dürre, P

    1994-01-01

    Using a PCR-based approach, we have cloned various sigma factor homologous genes from Clostridium acetobutylicum DSM 792. The nucleotide sequence of the dnaE-sigA operon has been determined and predicts two genes encoding 69- and 43-kDa proteins. The deduced DnaE amino acid sequence has approximately 30% amino acid identity with protein sequences of other primases. The putative sigA gene product shows high homology to primary sigma factors of various bacteria, most significantly to Bacillus subtilis and Staphylococcus aureus. Northern (RNA) blot analysis revealed that both genes from an operon, which is clearly expressed under conditions that allow for cell division. A promoter sequence with significant homology to the sigma H-dependent Bacillus promoters preceded the determined transcriptional start point, 182 bp upstream of the GUG start codon of dnaE. The homologous genes to Bacillus spp. sporulation sigma factors G, E, and K have been cloned and sequenced. Indirect evidence for the existence of sigma F was obtained by identification of a DNA sequence homologous to the respective Bacillus consensus promoter. Southern hybridization analysis indicated the presence of sigma D and sigma H homologous genes in C. acetobutylicum. A new gene group conserved within the eubacteria, but with yet unspecified functions, is described. The data presented here provide strong evidence that at least some of the complex regulation features of sporulation in B. subtilis are conserved in C. acetobutylicum and possibly Clostridium spp. Images PMID:7961408

  14. An Application of Six Sigma to Reduce Supplier Quality Cost

    NASA Astrophysics Data System (ADS)

    Gaikwad, Lokpriya Mohanrao; Teli, Shivagond Nagappa; Majali, Vijay Shashikant; Bhushi, Umesh Mahadevappa

    2016-01-01

    This article presents an application of Six Sigma to reduce supplier quality cost in manufacturing industry. Although there is a wider acceptance of Six Sigma in many organizations today, there is still a lack of in-depth case study of Six Sigma. For the present research the case study methodology was used. The company decided to reduce quality cost and improve selected processes using Six Sigma methodologies. Regarding the fact that there is a lack of case studies dealing with Six Sigma especially in individual manufacturing organization this article could be of great importance also for the practitioners. This paper discusses the quality and productivity improvement in a supplier enterprise through a case study. The paper deals with an application of Six Sigma define-measure-analyze-improve-control methodology in an industry which provides a framework to identify, quantify and eliminate sources of variation in an operational process in question, to optimize the operation variables, improve and sustain performance viz. process yield with well-executed control plans. Six Sigma improves the process performance (process yield) of the critical operational process, leading to better utilization of resources, decreases variations and maintains consistent quality of the process output.

  15. Pregnancy reduces brain sigma receptor function

    PubMed Central

    Bergeron, Richard; de Montigny, Claude; Debonnel, Guy

    1999-01-01

    Sigma (σ) receptors have recently been cloned, though their endogenous ligand(s) remain unidentified. However, some neuroactive steroids, such as progesterone, have a high affinity for these receptors. Some σ ligands, such as DTG, (+)-pentazocine and DHEA, act as σ ‘agonists' by potentiating the neuronal response to NMDA. Others, such as haloperidol, NE-100 and progesterone, act as σ ‘antagonists' by reversing the potentiations induced by σ ‘agonists'.We compared the effects of σ ‘agonists' in four series of female rats: in controls, at day 18 of pregnancy, at day 5 post-partum, and in ovariectomized rats following a 3-week treatment with a high dose of progesterone.In pregnant rats and following a 3-week treatment with progesterone, 10 fold higher doses of DTG, (+)-pentazocine and DHEA were required to elicit a selective potentiation of the NMDA response comparable to that obtained in control females. Conversely, at day 5 post-partum and following the 3-week treatment with a progesterone and after a 5-day washout, the potentiation of the NMDA response induced by the σ ‘agonist' DTG was greater than in control females.The present data suggest that endogenous progesterone acts as an ‘antagonist' at σ receptors. The resulting changes in the function of σ receptors during pregnancy and post-partum may be implicated in emotional phenomena occurring during these periods. PMID:10482906

  16. Sigma: Web Retrieval Interface for Nuclear Reaction Data

    SciTech Connect

    Pritychenko,B.; Sonzogni, A.A.

    2008-06-24

    The authors present Sigma, a Web-rich application which provides user-friendly access in processing and plotting of the evaluated and experimental nuclear reaction data stored in the ENDF-6 and EXFOR formats. The main interface includes browsing using a periodic table and a directory tree, basic and advanced search capabilities, interactive plots of cross sections, angular distributions and spectra, comparisons between evaluated and experimental data, computations between different cross section sets. Interactive energy-angle, neutron cross section uncertainties plots and visualization of covariance matrices are under development. Sigma is publicly available at the National Nuclear Data Center website at www.nndc.bnl.gov/sigma.

  17. Nucleon sigma term and quark condensate in nuclear matter

    SciTech Connect

    K. Tsushima; K. Saito; A. W. Thomas; A. Valcarce

    2007-03-01

    We study the bound nucleon sigma term and its effect on the quark condensate in nuclear matter. In the quark-meson coupling (QMC) model it is shown that the nuclear correction to the sigma term is small and negative. Thus, the correction decelerates the decrease of the quark condensate in nuclear matter. However, the quark condensate in nuclear matter is controlled primarily by the scalar-isoscalar sigma field of the model. It appreciably moderates the decrease relative to the leading term at densities around and larger than the normal nuclear matter density.

  18. Sigma: Web Retrieval Interface for Nuclear Reaction Data

    SciTech Connect

    Pritychenko, B. Sonzogni, A.A.

    2008-12-15

    We present Sigma, a Web-rich application which provides user-friendly access in processing and plotting of the evaluated and experimental nuclear reaction data stored in the ENDF-6 and EXFOR formats. The main interface includes browsing using a periodic table and a directory tree, basic and advanced search capabilities, interactive plots of cross sections, angular distributions and spectra, comparisons between evaluated and experimental data, computations between different cross section sets. Interactive energy-angle, neutron cross section uncertainties plots and visualization of covariance matrices are under development. Sigma is publicly available at the National Nuclear Data Center website at (http://www.nndc.bnl.gov/sigma)

  19. Development of ELISA kits for antibodies against avian reovirus using the sigmaC and sigmaB proteins expressed in the methyltropic yeast Pichia pastoris.

    PubMed

    Yang, Zi-Jiang; Wang, Chi-Young; Lee, Long-Huw; Chuang, Kuo-Pin; Lien, Yi-Yang; Yin, Hsien-Sheng; Tong, De-Wen; Xu, Xin-Gang; Liu, Hung-Jen

    2010-02-01

    Both the sigmaC and sigmaB proteins of avian reovirus (ARV) can induce type- and group-specific neutralizing antibodies, respectively. In this study, the full-length of S1133 sigmaC, 1071-1 sigmaC, S1133 sigmaB, and S1133 sigmaC-sigmaB fusion genes of ARV were cloned into a secreted vector pPICZalphaA and then integrated into the chromosome of Pichia pastoris for induced expression. Western blot assay showed that ARV sigmaC, sigmaB, and sigmaC-sigmaB fusion proteins were expressed and secreted into the medium. Two types of ELISA kits using equal mixtures of 1071-1sigmaC and S1133 sigmaB and S1133 sigmaC-sigmaB fusion proteins as antigens were developed. After a checker board titration for optimal conditions, the cut-off values of positive results for the 1071-1sigmaC/S1133 sigmaB and S1133 sigmaC-sigmaB ELISA kits were 0.24 and 0.12, respectively. Forty-four serum neutralization test-positive and twenty-eight serum neutralization-negative samples from vaccinated and commercial farm chickens were tested by the new ELISA kits and by the conventional ELISA. The new ELISA kits have higher positive rates than the conventional ELISA. The results revealed that the correlation rates for the serum neutralization titer and the absorbance values with the new ELISA kits and the conventional ELISA were 100% and 95.8%, respectively.

  20. Radio stars.

    PubMed

    Hjellming, R M; Wade, C M

    1971-09-17

    Up to the present time six classes of radio stars have been established. The signals are almost always very faint and drastically variable. Hence their discovery has owed as much to serendipity as to the highly sophisticated equipment and techniques that have been used. When the variations are regular, as with the pulsars, this characteristic can be exploited very successfully in the search for new objects as well as in the detailed study of those that are already known. The detection of the most erratically variable radio stars, the flare stars and the x-ray stars, is primarily a matter of luck and patience. In the case of the novas, one at least knows where and oughly when to look for radio emission. A very sensitive interferometer is clearly the best instrument to use in the initial detection of a radio star. The fact that weak background sources are frequently present makes it essential to prove that the position of a radio source agrees with that of a star to within a few arc seconds. The potential of radio astronomy for the study of radio stars will not be realized until more powerful instruments than those that are available today can be utilized. So far, we have been able to see only the most luminous of the radio stars. PMID:17836594

  1. Star Polymers.

    PubMed

    Ren, Jing M; McKenzie, Thomas G; Fu, Qiang; Wong, Edgar H H; Xu, Jiangtao; An, Zesheng; Shanmugam, Sivaprakash; Davis, Thomas P; Boyer, Cyrille; Qiao, Greg G

    2016-06-22

    Recent advances in controlled/living polymerization techniques and highly efficient coupling chemistries have enabled the facile synthesis of complex polymer architectures with controlled dimensions and functionality. As an example, star polymers consist of many linear polymers fused at a central point with a large number of chain end functionalities. Owing to this exclusive structure, star polymers exhibit some remarkable characteristics and properties unattainable by simple linear polymers. Hence, they constitute a unique class of technologically important nanomaterials that have been utilized or are currently under audition for many applications in life sciences and nanotechnologies. This article first provides a comprehensive summary of synthetic strategies towards star polymers, then reviews the latest developments in the synthesis and characterization methods of star macromolecules, and lastly outlines emerging applications and current commercial use of star-shaped polymers. The aim of this work is to promote star polymer research, generate new avenues of scientific investigation, and provide contemporary perspectives on chemical innovation that may expedite the commercialization of new star nanomaterials. We envision in the not-too-distant future star polymers will play an increasingly important role in materials science and nanotechnology in both academic and industrial settings.

  2. Radio stars.

    PubMed

    Hjellming, R M; Wade, C M

    1971-09-17

    Up to the present time six classes of radio stars have been established. The signals are almost always very faint and drastically variable. Hence their discovery has owed as much to serendipity as to the highly sophisticated equipment and techniques that have been used. When the variations are regular, as with the pulsars, this characteristic can be exploited very successfully in the search for new objects as well as in the detailed study of those that are already known. The detection of the most erratically variable radio stars, the flare stars and the x-ray stars, is primarily a matter of luck and patience. In the case of the novas, one at least knows where and oughly when to look for radio emission. A very sensitive interferometer is clearly the best instrument to use in the initial detection of a radio star. The fact that weak background sources are frequently present makes it essential to prove that the position of a radio source agrees with that of a star to within a few arc seconds. The potential of radio astronomy for the study of radio stars will not be realized until more powerful instruments than those that are available today can be utilized. So far, we have been able to see only the most luminous of the radio stars.

  3. Biochemical Pharmacology of the Sigma-1 Receptor.

    PubMed

    Chu, Uyen B; Ruoho, Arnold E

    2016-01-01

    The sigma-1 receptor (S1R) is a 223 amino acid two transmembrane (TM) pass protein. It is a non-ATP-binding nonglycosylated ligand-regulated molecular chaperone of unknown three-dimensional structure. The S1R is resident to eukaryotic mitochondrial-associated endoplasmic reticulum and plasma membranes with broad functions that regulate cellular calcium homeostasis and reduce oxidative stress. Several multitasking functions of the S1R are underwritten by chaperone-mediated direct (and indirect) interactions with ion channels, G-protein coupled receptors and cell-signaling molecules involved in the regulation of cell growth. The S1R is a promising drug target for the treatment of several neurodegenerative diseases related to cellular stress. In vitro and in vivo functional and molecular characteristics of the S1R and its interactions with endogenous and synthetic small molecules have been discovered by the use of pharmacologic, biochemical, biophysical, and molecular biology approaches. The S1R exists in monomer, dimer, tetramer, hexamer/octamer, and higher oligomeric forms that may be important determinants in defining the pharmacology and mechanism(s) of action of the S1R. A canonical GXXXG in putative TM2 is important for S1R oligomerization. The ligand-binding regions of S1R have been identified and include portions of TM2 and the TM proximal regions of the C terminus. Some client protein chaperone functions and interactions with the cochaperone 78-kDa glucose-regulated protein (binding immunoglobulin protein) involve the C terminus. Based on its biochemical features and mechanisms of chaperone action the possibility that the S1R is a member of the small heat shock protein family is discussed.

  4. Line profile asymmetries in chromospherically active stars

    NASA Technical Reports Server (NTRS)

    Dempsey, Robert C.; Bopp, Bernard W.; Strassmeier, Klaus G.; Granados, Arno F.; Henry, Gregory W.; Hall, Douglas S.

    1992-01-01

    A powerful, new probe of chromospheric activity, cross-correlation, has been developed and applied to a variety of stars. In this particular application, an entire CCD spectrum of an active star is correlated with the spectrum of a narrow-line, inactive star of similar spectral type and luminosity class. Using a number of strong lines in this manner enables the detection of absorption profile asymmetries at moderate resolution (lambda/Delta lambda about 40,000) and S/N 150:1. This technique has been applied to 14 systems mostly RS CVn's, with 10 not greater than nu sin i not greater than 50 km/s and P not less than 7 d. Distortions were detected for the first time in five systems: Sigma Gem, IM Peg, GX Lib, UV Crb, and Zeta And. Detailed modeling, incorporating both spectral line profiles and broad-band photometry, is applied to Sigma Gem. Profile asymmetries for this star are fitted by two high-latitude spots covering 5 percent of the stellar surface. The derived spot temperature of 3400 K is lower than found in previous studies. In addition, two well-known systems have been studied: HD 199178 and V711 Tau. Polar spots are found on both.

  5. Predictions from star formation in the multiverse

    SciTech Connect

    Bousso, Raphael; Leichenauer, Stefan

    2010-03-15

    We compute trivariate probability distributions in the landscape, scanning simultaneously over the cosmological constant, the primordial density contrast, and spatial curvature. We consider two different measures for regulating the divergences of eternal inflation, and three different models for observers. In one model, observers are assumed to arise in proportion to the entropy produced by stars; in the others, they arise at a fixed time (5 or 10x10{sup 9} years) after star formation. The star formation rate, which underlies all our observer models, depends sensitively on the three scanning parameters. We employ a recently developed model of star formation in the multiverse, a considerable refinement over previous treatments of the astrophysical and cosmological properties of different pocket universes. For each combination of observer model and measure, we display all single and bivariate probability distributions, both with the remaining parameter(s) held fixed and marginalized. Our results depend only weakly on the observer model but more strongly on the measure. Using the causal diamond measure, the observed parameter values (or bounds) lie within the central 2{sigma} of nearly all probability distributions we compute, and always within 3{sigma}. This success is encouraging and rather nontrivial, considering the large size and dimension of the parameter space. The causal patch measure gives similar results as long as curvature is negligible. If curvature dominates, the causal patch leads to a novel runaway: it prefers a negative value of the cosmological constant, with the smallest magnitude available in the landscape.

  6. M sub 1 muscarinic antagonists interact with. sigma. recognition sites

    SciTech Connect

    Hudkins, R.L. ); DeHaven-Hudkins, D.L. )

    1991-01-01

    The M{sub 1}-selective muscarinic antagonists aprophen, caramiphen, carbetapentane, 2-DAEX, dicyclomine, hexahydrosiladifenidol, iodocaramiphen, nitrocaramiphen, oxybutynin and trihexyphenidyl potently inhibited binding to {sigma} sites in brain. Both basic ester and non-ester structural type compounds which exhibit affinity for the muscarinic receptor also demonstrated affinity for the {sigma} site, while the classical antimuscarinic agents atropine and QNB, and the tricyclic pirenzepine, were ineffective in binding to this site. The authors also observed a significant correlation between the K{sub i} values for {sigma}compounds to inhibit ({sup 3}H)pirenzepine binding and their IC{sub 50} values to inhibit carbachol-stimulated phosphoinositide turnover. These observations may aid in elucidating the relationship of {sigma} binding to inhibition of phosphoinositide turnover stimulated by cholinergic agonists.

  7. Dilatonic non-linear sigma models and Ricci flow extensions

    NASA Astrophysics Data System (ADS)

    Carfora, M.; Marzuoli, A.

    2016-09-01

    We review our recent work describing, in terms of the Wasserstein geometry over the space of probability measures, the embedding of the Ricci flow in the renormalization group flow for dilatonic non-linear sigma models.

  8. The Six Sigma initiative at Mount Sinai Medical Center.

    PubMed

    Chassin, Robert

    2008-01-01

    Lean Six Sigma, in various forms, has been used widely in many Fortune 500 companies. Motorola, General Electric, Sony, American Express, and Bechtel all use Six Sigma to improve quality and performance. While the impact of this methodology has been documented extensively by the press in manufacturing and transactional settings, less evidence is available regarding its utility in health care environments. Mount Sinai Medical Center initiated a Six Sigma program in 2000 to determine its applicability and value in a large academic medical center. This article discusses Mount Sinai Medical Center's experience adapting this methodology to improve both patient care and business processes and outcomes. We present an overview of Six Sigma, and offer examples of projects undertaken using this data-driven approach to performance improvement. Lastly, the article provides insights and lessons learned regarding this organization-wide experience.

  9. Milestone Report - M31SW030904 - Sigma Team Coordination Meeting

    SciTech Connect

    Jubin, Robert Thomas

    2010-11-24

    This documents the completion of the FCR&D Level 3 milestone for the Off-Gas Sigma Team - ORNL work package (FTOR11SW0309), “Sigma Team Coordination Meeting” (M31SW030904), due 30 November 10. The subject meeting was held at Idaho National Laboratory on October 12 and 13, 2010. The agenda and meeting minutes are attached to this memo.

  10. Hamilton-Jacobi approach to cosmology with nonlinear sigma model

    NASA Astrophysics Data System (ADS)

    Kerner, Richard; van Holten, Jan-Willem

    2016-05-01

    We start with a short introduction of the role that constraints and Lagrange multiplers play in variational calculus. After recalling briefly the properties of the nonlinear sigma model, we show how the Hamilton-Jacobi method can be applied to find its solutions. We discuss the importance of the Hamiltonian constraint in the standard cosmological model, and finally, apply the Hamilton-Jacobi method to the solution of coupled gravitational and sigma-field equations.

  11. Killing Sections and Sigma Models with Lie Algebroid Targets

    NASA Astrophysics Data System (ADS)

    Bruce, Andrew James

    2016-08-01

    We define and examine the notion of a Killing section of a Riemannian Lie algebroid as a natural generalisation of a Killing vector field. We show that the various expression for a vector field to be Killing naturally generalise to the setting of Lie algebroids. As an application we examine the internal symmetries of a class of sigma models for which the target space is a Riemannian Lie algebroid. Critical points of these sigma models are interpreted as generalised harmonic maps.

  12. Lean sigma--will it work for healthcare?

    PubMed

    Bahensky, James A; Roe, Janet; Bolton, Romy

    2005-01-01

    The manufacturing industry has been using Lean Sigma for years in pursuit of continuous improvement to obtain a competitive advantage. The objectives of these efforts are to use the Lean techniques for reducing cycle times and the Six Sigma concepts for reducing product defects. The Iowa Business Council with several advocates worked with the University of Iowa Hospital and Clinics (UIHC) and two other Iowa hospitals to determine whether Lean Sigma is adaptable in healthcare. A team of 15 people at UIHC used the Kaizen Breakthrough Methodology over a five-day period in an aggressive identification and elimination of non-value added activities in Radiology CT scanning. The results exceeded the initial project objectives and indicated that Lean Sigma is applicable in healthcare. Overall, the Lean Sigma project increased revenue by approximately $750,000 per year. The Kaizen process proved to be successful and interesting. Within three days, the team installed new work flow processes. This implementation-oriented approach is what differentiates Lean Sigma from other quality improvement processes.

  13. Genome-wide analysis of the general stress response network in Escherichia coli: sigmaS-dependent genes, promoters, and sigma factor selectivity.

    PubMed

    Weber, Harald; Polen, Tino; Heuveling, Johanna; Wendisch, Volker F; Hengge, Regine

    2005-03-01

    The sigmaS (or RpoS) subunit of RNA polymerase is the master regulator of the general stress response in Escherichia coli. While nearly absent in rapidly growing cells, sigmaS is strongly induced during entry into stationary phase and/or many other stress conditions and is essential for the expression of multiple stress resistances. Genome-wide expression profiling data presented here indicate that up to 10% of the E. coli genes are under direct or indirect control of sigmaS and that sigmaS should be considered a second vegetative sigma factor with a major impact not only on stress tolerance but on the entire cell physiology under nonoptimal growth conditions. This large data set allowed us to unequivocally identify a sigmaS consensus promoter in silico. Moreover, our results suggest that sigmaS-dependent genes represent a regulatory network with complex internal control (as exemplified by the acid resistance genes). This network also exhibits extensive regulatory overlaps with other global regulons (e.g., the cyclic AMP receptor protein regulon). In addition, the global regulatory protein Lrp was found to affect sigmaS and/or sigma70 selectivity of many promoters. These observations indicate that certain modules of the sigmaS-dependent general stress response can be temporarily recruited by stress-specific regulons, which are controlled by other stress-responsive regulators that act together with sigma70 RNA polymerase. Thus, not only the expression of genes within a regulatory network but also the architecture of the network itself can be subject to regulation. PMID:15716429

  14. STARS no star on Kauai

    SciTech Connect

    Jones, M.

    1993-04-01

    The island of Kuai, home to the Pacific Missile Range Facility, is preparing for the first of a series of Star Wars rocket launches expected to begin early this year. The Strategic Defense Initiative plans 40 launches of the Stategic Target System (STARS) over a 10-year period. The focus of the tests appears to be weapons and sensors designed to combat multiple-warhead ICBMs, which will be banned under the START II Treaty that was signed in January. The focus of this article is to express the dubious value of testing the STARS at a time when their application will not be an anticipated problem.

  15. Functional modules of sigma factor regulons guarantee adaptability and evolvability

    NASA Astrophysics Data System (ADS)

    Binder, Sebastian C.; Eckweiler, Denitsa; Schulz, Sebastian; Bielecka, Agata; Nicolai, Tanja; Franke, Raimo; Häussler, Susanne; Meyer-Hermann, Michael

    2016-02-01

    The focus of modern molecular biology turns from assigning functions to individual genes towards understanding the expression and regulation of complex sets of molecules. Here, we provide evidence that alternative sigma factor regulons in the pathogen Pseudomonas aeruginosa largely represent insulated functional modules which provide a critical level of biological organization involved in general adaptation and survival processes. Analysis of the operational state of the sigma factor network revealed that transcription factors functionally couple the sigma factor regulons and significantly modulate the transcription levels in the face of challenging environments. The threshold quality of newly evolved transcription factors was reached faster and more robustly in in silico testing when the structural organization of sigma factor networks was taken into account. These results indicate that the modular structures of alternative sigma factor regulons provide P. aeruginosa with a robust framework to function adequately in its environment and at the same time facilitate evolutionary change. Our data support the view that widespread modularity guarantees robustness of biological networks and is a key driver of evolvability.

  16. Functional modules of sigma factor regulons guarantee adaptability and evolvability.

    PubMed

    Binder, Sebastian C; Eckweiler, Denitsa; Schulz, Sebastian; Bielecka, Agata; Nicolai, Tanja; Franke, Raimo; Häussler, Susanne; Meyer-Hermann, Michael

    2016-01-01

    The focus of modern molecular biology turns from assigning functions to individual genes towards understanding the expression and regulation of complex sets of molecules. Here, we provide evidence that alternative sigma factor regulons in the pathogen Pseudomonas aeruginosa largely represent insulated functional modules which provide a critical level of biological organization involved in general adaptation and survival processes. Analysis of the operational state of the sigma factor network revealed that transcription factors functionally couple the sigma factor regulons and significantly modulate the transcription levels in the face of challenging environments. The threshold quality of newly evolved transcription factors was reached faster and more robustly in in silico testing when the structural organization of sigma factor networks was taken into account. These results indicate that the modular structures of alternative sigma factor regulons provide P. aeruginosa with a robust framework to function adequately in its environment and at the same time facilitate evolutionary change. Our data support the view that widespread modularity guarantees robustness of biological networks and is a key driver of evolvability. PMID:26915971

  17. Functional modules of sigma factor regulons guarantee adaptability and evolvability

    PubMed Central

    Binder, Sebastian C.; Eckweiler, Denitsa; Schulz, Sebastian; Bielecka, Agata; Nicolai, Tanja; Franke, Raimo; Häussler, Susanne; Meyer-Hermann, Michael

    2016-01-01

    The focus of modern molecular biology turns from assigning functions to individual genes towards understanding the expression and regulation of complex sets of molecules. Here, we provide evidence that alternative sigma factor regulons in the pathogen Pseudomonas aeruginosa largely represent insulated functional modules which provide a critical level of biological organization involved in general adaptation and survival processes. Analysis of the operational state of the sigma factor network revealed that transcription factors functionally couple the sigma factor regulons and significantly modulate the transcription levels in the face of challenging environments. The threshold quality of newly evolved transcription factors was reached faster and more robustly in in silico testing when the structural organization of sigma factor networks was taken into account. These results indicate that the modular structures of alternative sigma factor regulons provide P. aeruginosa with a robust framework to function adequately in its environment and at the same time facilitate evolutionary change. Our data support the view that widespread modularity guarantees robustness of biological networks and is a key driver of evolvability. PMID:26915971

  18. The sigma54 global regulon in Salmonella enterica serovar Typhimurium 14028s: an extensive array of intragenic sigma54 regulatory sites revealed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An essential determinant of a transcriptional regulon is the sigma factor that associates with core RNA polymerase (E) to direct promoter-specific binding and transcription initiation by the holoenzyme (Esigma). In addition to the primary sigma factor, sigma70, S. Typhimurium has five alternative si...

  19. SigmaCLIPSE = presentation management + NASA CLI PS + SQL

    NASA Technical Reports Server (NTRS)

    Weiss, Bernard P., Jr.

    1990-01-01

    SigmaCLIPSE provides an expert systems and 'intelligent' data base development program for diverse systems integration environments that require support for automated reasoning and expert systems technology, presentation management, and access to 'intelligent' SQL data bases. The SigmaCLIPSE technology and and its integrated ability to access 4th generation application development and decision support tools through a portable SQL interface, comprises a sophisticated software development environment for solving knowledge engineering and expert systems development problems in information intensive commercial environments -- financial services, health care, and distributed process control -- where the expert system must be extendable -- a major architectural advantage of NASA CLIPS. SigmaCLIPSE is a research effort intended to test the viability of merging SQL data bases with expert systems technology.

  20. sigma model approach to the heterotic string theory

    SciTech Connect

    Sen, A.

    1985-09-01

    Relation between the equations of motion for the massless fields in the heterotic string theory, and the conformal invariance of the sigma model describing the propagation of the heterotic string in arbitrary background massless fields is discussed. It is emphasized that this sigma model contains complete information about the string theory. Finally, we discuss the extension of the Hull-Witten proof of local gauge and Lorentz invariance of the sigma-model to higher order in ..cap alpha..', and the modification of the transformation laws of the antisymmetric tensor field under these symmetries. Presence of anomaly in the naive N = 1/2 supersymmetry transformation is also pointed out in this context. 12 refs.

  1. sigma(B) and sigma(L) contribute to Listeria monocytogenes 10403S response to the antimicrobial peptides SdpC and nisin.

    PubMed

    Palmer, M Elizabeth; Wiedmann, Martin; Boor, Kathryn J

    2009-11-01

    The ability of the foodborne pathogen Listeria monocytogenes to survive antimicrobial treatments is a public health concern; therefore, this study was designed to investigate genetic mechanisms contributing to antimicrobial response in L. monocytogenes. In previous studies, the putative bacteriocin immunity gene lmo2570 was predicted to be regulated by the stress responsive alternative sigma factor, sigma(B). As the alternative sigma factor sigma(L) controls expression of genes important for resistance to some antimicrobial peptides, we hypothesized roles for lmo2570, sigma(B), and sigma(L) in L. monocytogenes antimicrobial response. Results from phenotypic characterization of a L. monocytogenes lmo2570 null mutant suggested that this gene does not contribute to resistance to nisin or to SdpC, an antimicrobial peptide produced by some strains of Bacillus subtilis. While lmo2570 transcript levels were confirmed to be sigma(B) dependent, they were sigma(L) independent and were not affected by the presence of nisin under the conditions used in this study. In spot-on-lawn assays with the SdpC-producing B. subtilis EG351, the L. monocytogenes DeltasigB, DeltasigL, and DeltasigB/DeltasigL strains all showed increased sensitivity to SdpC, indicating that both sigma(B) and sigma(L) regulate genes contributing to SdpC resistance. Nisin survival assays showed that sigma(B) and sigma(L) both affect L. monocytogenes sensitivity to nisin in broth survival assays; that is, a sigB null mutant is more resistant than the parent strain to nisin, while a sigB null mutation in DeltasigL background leads to reduced nisin resistance. In summary, while the sigma(B)-dependent lmo2570 does not contribute to resistance of L. monocytogenes to nisin or SdpC, both sigma(B) and sigma(L) contribute to the L. monocytogenes antimicrobial response. PMID:19642919

  2. High-Amplitude δ Scuti and SX Phoenicis Stars: The Effects of Chemical Composition on Pulsations and the Period-Luminosity Relation

    NASA Astrophysics Data System (ADS)

    Templeton, Matthew; Basu, Sarbani; Demarque, Pierre

    2002-09-01

    We present a theoretical study of the radially pulsating δ Scuti and SX Phoenicis variables, concentrating on the blue straggler SX Phoenicis variables found in globular clusters. We have evolved a grid of stellar models with the metal abundance of the globular cluster M55, including models with alpha-enhanced metal abundances, and tested these models for radial pulsations observed in the high-amplitude δ Scuti and SX Phoenicis stars. Our grid includes models with globally enriched helium content to simulate the effects of stellar collisions and global mixing possible in blue stragglers. We find that global enrichment of helium strongly affects the temperature and luminosity of a given star, but the location of the instability strip blue edge and the slope of the period-luminosity (PL) relation are unchanged. This suggests that the PL relation is not affected by blue straggler formation if blue stragglers are fully mixed stellar mergers. Our blue edges and PL relations are in agreement with other theoretical determinations and also with the observational PL relation of M55, but they are not in agreement with the PL relation previously derived for high-amplitude δ Scuti stars in the field. Analysis of the double-mode variable, V41, suggests either that the star may not be pulsating in the first and second overtones as claimed or that normal stellar models may not be accurate models of blue straggler stars.

  3. Added value in health care with six sigma.

    PubMed

    Lenaz, Maria P

    2004-06-01

    Six sigma is the structured application of the tools and techniques of quality management applied on a project basis that can enable organizations to achieve superior performance and strategic business results. The Greek character sigma has been used as a statistical term that measures how much a process varies from perfection, based on the number of defects per million units. Health care organizations using this model proceed from the lower levels of quality performance to the highest level, in which the process is nearly error free.

  4. THE STORY OF SIGMA HYPERNUCLEI - A MODERN FABLE.

    SciTech Connect

    CHRIEN,R.E.

    1999-02-19

    The reality of {Sigma} hypernuclei has been the subject of intense concern among experimenters and theoreticians for more than 20 years. The possible existence of {Sigma} hypernuclei was first suggested by a pioneering experiment on a {sup 9}Be target at the CERN PS. There were reported to be two narrow ({Gamma} < 8 MeV) peaks in the continuum region. This finding was quite unexpected since the widths of {Sigma} states were believed to be large due to the strong conversion process. It is obvious that if such relatively long-lived systems were confirmed unambiguously by experiment, their masses and widths provide important constraints on the {Sigma}N effective interaction and its relation to the {Lambda}N and NN interactions. Since the {Sigma} carries isospin, the role of isospin and isospin conservation in hadronic reactions could be explored. This report stimulated a number of subsequent experiments at the BNL-AGS and KEK, along with further experiments with a specially created short kaon beam at the CERN PS. Experimental data were reported for different targets at different momenta and at different conditions. Various tagging techniques were employed to suppress backgrounds, but always at the expense of a reduction in statistical quality. Because of problems with resolution and statistics, contradictions among the different sets of data resulted more often in clouding the issues than clarifying them. Thus, up until a few years ago, there was no statistically clear confirmation of this surprising finding. In the last few years, however, a series of definitive experiments has been performed at the BNL-AGS in an effort to resolve the discrepancies and settle the controversy. Besides repeating the initial experiment on Be, a target of {sup 6}Li was run. The earlier stopped kaon data on {sup 4}He was repeated in an in-flight experiment, and the suggestion of a {Sigma} bound state, with virtually pure isospin, confirmed. We now have a better understanding of the role

  5. ATOMIC DIFFUSION AND MIXING IN OLD STARS. III. ANALYSIS OF NGC 6397 STARS UNDER NEW CONSTRAINTS

    SciTech Connect

    Nordlander, T.; Korn, A. J.; Richard, O.; Lind, K.

    2012-07-01

    We have previously reported on chemical abundance trends with evolutionary state in the globular cluster NGC 6397 discovered in analyses of spectra taken with FLAMES at the Very Large Telescope. Here, we reinvestigate the FLAMES-UVES sample of 18 stars, ranging from just above the turnoff point to the red giant branch below the bump. Inspired by new calibrations of the infrared flux method, we adopt a set of hotter temperature scales. Chemical abundances are determined for six elements (Li, Mg, Ca, Ti, Cr, and Fe). Signatures of cluster-internal pollution are identified and corrected for in the analysis of Mg. On the modified temperature scales, evolutionary trends in the abundances of Mg and Fe are found to be significant at the 2{sigma} and 3{sigma} levels, respectively. The detailed evolution of abundances for all six elements agrees with theoretical isochrones, calculated with effects of atomic diffusion and a weak to moderately strong efficiency of turbulent mixing. The age of these models is compatible with the external determination from the white dwarf cooling sequence. We find that the abundance analysis cannot be reconciled with the strong turbulent-mixing efficiency inferred elsewhere for halo field stars. A weak mixing efficiency reproduces observations best, indicating a diffusion-corrected primordial lithium abundance of log {epsilon}(Li) = 2.57 {+-} 0.10. At 1.2{sigma}, this value agrees well with Wilkinson Microwave Anisotropy Probe calibrated big bang nucleosynthesis predictions.

  6. Theoretical study of the AlO blue-green (B2Sigma + - X2Sigma +) band system

    NASA Technical Reports Server (NTRS)

    Partridge, H.; Langhoff, S. R.; Lengsfield, B. H., III; Liu, B.

    1983-01-01

    Two independent, extensive theoretical calculations are reported for the relative band strengths of the AlO (B2Sigma + - X2Sigma +) blue-green system and for the radiative lifetimes of the lowest few vibrational levels of the B2Sigma(+) state. The theoretical lifetimes, which include a small (less than -.5 percent) contribution from bound-bound transitions into the A2Pi state, are in excellent agreement with laser fluorescence studies. The theoretical lifetimes increase monotonically and very slowly with increasing vibrational quantum number. The relative band strengths for the blue-green system derived from the two theoretical calculations are in excellent agreement, but differ systematically from the relative band strengths of Linton and Nicholls (1969). The present results suggest that their self-absorption corrections are not large enough, resulting in relative intensities that are too large, especially for the weak bands with r centroids less than 1.5 A.

  7. Relativistic tidal properties of neutron stars

    SciTech Connect

    Damour, Thibault; Nagar, Alessandro

    2009-10-15

    We study the various linear responses of neutron stars to external relativistic tidal fields. We focus on three different tidal responses, associated to three different tidal coefficients: (i) a gravito-electric-type coefficient G{mu}{sub l}=[length]{sup 2l+1} measuring the lth-order mass multipolar moment GM{sub a{sub 1}}{sub ...a{sub I}} induced in a star by an external lth-order gravito-electric tidal field G{sub a{sub 1}}{sub ...a{sub I}}; (ii) a gravito-magnetic-type coefficient G{sigma}{sub l}=[length]{sup 2l+1} measuring the lth spin multipole moment GS{sub a{sub 1}}{sub ...a{sub I}} induced in a star by an external lth-order gravito-magnetic tidal field H{sub a{sub 1}}{sub ...a{sub I}}; and (iii) a dimensionless 'shape' Love number h{sub l} measuring the distortion of the shape of the surface of a star by an external lth-order gravito-electric tidal field. All the dimensionless tidal coefficients G{mu}{sub l}/R{sup 2l+1}, G{sigma}{sub l}/R{sup 2l+1}, and h{sub l} (where R is the radius of the star) are found to have a strong sensitivity to the value of the star's 'compactness'c{identical_to}GM/(c{sub 0}{sup 2}R) (where we indicate by c{sub 0} the speed of light). In particular, G{mu}{sub l}/R{sup 2l+1}{approx}k{sub l} is found to strongly decrease, as c increases, down to a zero value as c is formally extended to the 'black hole (BH) limit'c{sup BH}=1/2. The shape Love number h{sub l} is also found to significantly decrease as c increases, though it does not vanish in the formal limit c{yields}c{sup BH}, but is rather found to agree with the recently determined shape Love numbers of black holes. The formal vanishing of {mu}{sub l} and {sigma}{sub l} as c{yields}c{sup BH} is a consequence of the no-hair properties of black holes. This vanishing suggests, but in no way proves, that the effective action describing the gravitational interactions of black holes may not need to be augmented by nonminimal worldline couplings.

  8. Bulk viscosity of superfluid hyperon stars

    SciTech Connect

    Gusakov, Mikhail E.; Kantor, Elena M.

    2008-10-15

    We calculate the bulk viscosity due to nonequilibrium weak processes in superfluid nucleon-hyperon matter of neutron stars. For that, the dissipative relativistic hydrodynamics, formulated eariler [M. E. Gusakov, Phys. Rev. D 76, 083001 (2007).] for superfluid mixtures, is extended to the case when both nucleons and hyperons are superfluid. It is demonstrated that in the most general case (when neutrons, protons, {lambda}, and {sigma}{sup -} hyperons are superfluid), nonequilibrium weak processes generate 16 bulk viscosity coefficients, with only three of them being independent. In addition, we correct an inaccuracy in a widely used formula for the bulk viscosity of nonsuperfluid nucleon-hyperon matter.

  9. Star quality.

    PubMed

    Dent, Emma

    2007-09-20

    Around 150 wards are participating in the voluntary Star Wards scheme to provide mental health inpatients with more activities with therapeutic value. Suggested activities range from a library, to horse riding Internet access and comedy. Service users are particularly keen to have more exercise, which can be a challenge in inpatient settings. PMID:17970387

  10. Star Power

    ScienceCinema

    None

    2016-07-12

    The U.S. Department of Energy's Princeton Plasma Physics Laboratory has released ''Star Power,'' a new informational video that uses dramatic and beautiful images and thought-provoking interviews to highlight the importance of the Laboratory's research into magnetic fusion.

  11. Star Power

    SciTech Connect

    2014-10-17

    The U.S. Department of Energy's Princeton Plasma Physics Laboratory has released ''Star Power,'' a new informational video that uses dramatic and beautiful images and thought-provoking interviews to highlight the importance of the Laboratory's research into magnetic fusion.

  12. STAR FORMATION IN 30 DORADUS

    SciTech Connect

    De Marchi, Guido; Spezzi, Loredana; Sirianni, Marco; Andersen, Morten; Paresce, Francesco; Panagia, Nino; Mutchler, Max; Whitmore, Bradley C.; Bond, Howard; Beccari, Giacomo; Balick, Bruce; Dopita, Michael A.; Frogel, Jay A.; Calzetti, Daniela; Marcella Carollo, C.; Disney, Michael J.; Hall, Donald N. B.; Holtzman, Jon A.; Kimble, Randy A.; McCarthy, Patrick J.

    2011-09-20

    Using observations obtained with the Wide-Field Camera 3 on board the Hubble Space Telescope, we have studied the properties of the stellar populations in the central regions of 30 Dor in the Large Magellanic Cloud. The observations clearly reveal the presence of considerable differential extinction across the field. We characterize and quantify this effect using young massive main-sequence stars to derive a statistical reddening correction for most objects in the field. We then search for pre-main-sequence (PMS) stars by looking for objects with a strong (>4{sigma}) H{alpha} excess emission and find about 1150 of them over the entire field. Comparison of their location in the Hertzsprung-Russell diagram with theoretical PMS evolutionary tracks for the appropriate metallicity reveals that about one-third of these objects are younger than {approx}4 Myr, compatible with the age of the massive stars in the central ionizing cluster R 136, whereas the rest have ages up to {approx}30 Myr, with a median age of {approx}12 Myr. This indicates that star formation has proceeded over an extended period of time, although we cannot discriminate between an extended episode and a series of short and frequent bursts that are not resolved in time. While the younger PMS population preferentially occupies the central regions of the cluster, older PMS objects are more uniformly distributed across the field and are remarkably few at the very center of the cluster. We attribute this latter effect to photo-evaporation of the older circumstellar disks caused by the massive ionizing members of R 136.

  13. Why is "S" a Biased Estimate of [sigma]?

    ERIC Educational Resources Information Center

    Sanqui, Jose Almer T.; Arnholt, Alan T.

    2011-01-01

    This article describes a simulation activity that can be used to help students see that the estimator "S" is a biased estimator of [sigma]. The activity can be implemented using either a statistical package such as R, Minitab, or a Web applet. In the activity, the students investigate and compare the bias of "S" when sampling from different…

  14. Strategically Focused Training in Six Sigma Way: A Case Study

    ERIC Educational Resources Information Center

    Pandey, Ashish

    2007-01-01

    Purpose: The purpose of the current study is to examine the utility of Six Sigma interventions as a performance measure and explore its applicability for making the training design and delivery operationally efficient and strategically effective. Design/methodology/approach: This is a single revelatory case study. Data were collected from multiple…

  15. Lean-Six Sigma: tools for rapid cycle cost reduction.

    PubMed

    Caldwell, Chip

    2006-10-01

    Organizational costs can be grouped as process cost, cost of quality, and cost of poor quality. Providers should train managers in the theory and application of Lean-Six Sigma, including the seven categories of waste and how to remove them. Healthcare financial executives should work with managers in eliminating waste to improve service and reduce costs.

  16. Sigma ligand S14905 and locomotor activity in mice.

    PubMed

    Hascoet, M; Bourin, M; Payeur, R; Lombet, A; Peglion, J L

    1995-12-01

    The binding and locomotor profile of a new sigma ligand, S14905, (isobutyl-N-(1-indan-2yl-piperid-4-yl)N-methyl carbamate, furamate) was studied. The binding data revealed that S14905 has a high affinity for sigma receptors and very low affinity for both dopamine D1 and D2 receptors. We have demonstrated that this sigma ligand prevents the locomotor stimulation induced by morphine (32 and 64 mg/kg), cocaine (16 mg/kg), amphetamine (4 mg/kg) and adrafinil (32 mg/kg) at doses lower than those required to depress spontaneous locomotor activity. The antagonism observed in the present study seems to be more specific of morphine induced hyperlocomotion. The high affinity of this compound for sigma receptors makes it a good choice to study the role of this receptor in the CNS. In addition, S14905 does not directly block dopamine receptors but may modulate them in some manner, and would thus warrant further study as a potential atypical antipsychotic agent, and an antagonist for the hyperactivity induced by opiate drug. PMID:8998401

  17. Shake for Sigma, Pray for Pi: Classroom Orbital Overlap Analogies

    ERIC Educational Resources Information Center

    Dicks, Andrew P.

    2011-01-01

    An introductory organic classroom demonstration is discussed where analogies are made between common societal hand contact and covalent bond formation. A handshake signifies creation of a [sigma] bond ("head-on" orbital overlap), whereas the action of praying illustrates "sideways" overlap and generation of a [pi] bond. The nature of orbital and…

  18. Sigma ligand S14905 and locomotor activity in mice.

    PubMed

    Hascoet, M; Bourin, M; Payeur, R; Lombet, A; Peglion, J L

    1995-12-01

    The binding and locomotor profile of a new sigma ligand, S14905, (isobutyl-N-(1-indan-2yl-piperid-4-yl)N-methyl carbamate, furamate) was studied. The binding data revealed that S14905 has a high affinity for sigma receptors and very low affinity for both dopamine D1 and D2 receptors. We have demonstrated that this sigma ligand prevents the locomotor stimulation induced by morphine (32 and 64 mg/kg), cocaine (16 mg/kg), amphetamine (4 mg/kg) and adrafinil (32 mg/kg) at doses lower than those required to depress spontaneous locomotor activity. The antagonism observed in the present study seems to be more specific of morphine induced hyperlocomotion. The high affinity of this compound for sigma receptors makes it a good choice to study the role of this receptor in the CNS. In addition, S14905 does not directly block dopamine receptors but may modulate them in some manner, and would thus warrant further study as a potential atypical antipsychotic agent, and an antagonist for the hyperactivity induced by opiate drug.

  19. SIGMA Release v1.2 - Capabilities, Enhancements and Fixes

    SciTech Connect

    Mahadevan, Vijay; Grindeanu, Iulian R.; Ray, Navamita; Jain, Rajeev; Wu, Danqing

    2015-09-30

    In this report, we present details on SIGMA toolkit along with its component structure, capabilities, and feature additions in FY15, release cycles, and continuous integration process. These software processes along with updated documentation are imperative to successfully integrate and utilize in several applications including the SHARP coupled analysis toolkit for reactor core systems funded under the NEAMS DOE-NE program.

  20. Noise Simulation of Continuous-Time {sigma}{delta} Modulators

    SciTech Connect

    Arias, J.; Quintanilla, L.; Bisbal, D.; San Pablo, J.; Enriquez, L.; Vicente, J.; Barbolla, J.

    2005-08-25

    In this work, an approach for the simulation of the effect of noise sources in the performance of continuous-time {delta}{sigma} modulators is presented. Electrical noise including thermal noise, 1/f noise and clock jitter are included in a simulation program and their impact on the system performance is analyzed.

  1. Gauge invariance and the sigma model for the heterotic string

    SciTech Connect

    Hamada, K.J.; Kodaira, J.; Saito, J.

    1987-06-01

    The authors consider the heterotic string in arbitrary background gauge fields. The full gauge Chern-Simmons terms are shown to be reproduced in the divergent terms of the corresponding sigma model to the two-loop order. The role of the Chern-Simmons terms is discussed from the viewpoint of the local gauge invariance.

  2. Using Six-Sigma To Change and Measure Improvement.

    ERIC Educational Resources Information Center

    Feld, Karl G.; Stone, William K.

    2002-01-01

    Explains why Honeywell's Market Research Department replaced its traditional data collection and paper-based tabulation with blended modes, including electronic interviewing and real-time reporting. Describes how the Six-Sigma quality control process demonstrated that a hybrid approach with blended modes and Web-based reporting tools could deliver…

  3. The β-FUNCTION in Topological Sigma Models

    NASA Astrophysics Data System (ADS)

    Birmingham, Danny; Rakowski, Mark

    The one-loop β-function is computed for topological sigma models. By gauge fixing the topological shift symmetry in the delta-function gauge, we find that the theory is finite with vanishing β-function. A similar result is shown to hold for supersymmetric quantum mechanics.

  4. The Rothney Astrophysical Observatory's Wide Field Variable Star Search Program

    NASA Astrophysics Data System (ADS)

    Williams, M. D.; Milone, E. F.

    2005-05-01

    We describe a variable star search program being carried out on a 0.5-m f/1 Patrol Camera at the RAO. The detector is a 4Kx4K chip mounted in an FLI camera, purchased by P. Brown (UWO). The 4.4 by 4.4 deg. image frames provide stellar images of 2 pixels (FWHM). Results from the first well-studied night sequence reveal a significant number of apparently real variability detections. The search covers stars in a range of 11-14 magnitudes in the natural system (approximately Johnson-Cousins R). In the first field studied there are 8500 stars in this range, with average 1 sigma errors of 0.05 magnitudes. We expect to achieve 1 sigma errors smaller than 0.02 magn. for stars brighter than 12 magn. Results show that we are close to the predicted noise levels with 1100 stars within this precision limit. There are 75 stars that have 1 sigma errors below 0.01 magnitude. This level of precision allows for the detection of hot Jupiter transits that have a decrease in brightness on the order of 0.03 magnitudes (or less). The Patrol Camera is a former Baker-Nunn satellite tracking camera, modified by DFM Engineering as part of a retrofit supervised by M.J. Mazur, in a collaboration funded by grants from the Alberta Science Research Authority (to EFM), and others. The survey is being carried out by MDW as part of his PhD program and is being supported in part by NSERC grants to EFM and the University of Calgary Department of Physics & Astronomy.

  5. Permanent active longitudes and activity cycles on RS CVn stars

    NASA Astrophysics Data System (ADS)

    Berdyugina, Svetlana V.; Tuominen, Ilkka

    1998-08-01

    A new analysis of the published long-term photometric observations has revealed permanent active-longitude structures in four RS CVn stars: EI Eri, II Peg, sigma Gem, and HR 7275. Two active longitudes separated by half of the period are found to dominate on the surface during all available seasons. The positions of the longitudes on three stars (EI Eri, II Peg, HR 7275) are migrating in the orbital reference frame, and there is no preferred orientation with respect to the line of centres in the binaries. The rate of migration is approximately constant. In case of sigma Gem the active longitude migration is synchronized with the orbital motion in the direction of the line of centres in the binary. The active region lifetimes can be longer than the time span of the observations (>=15 yr). The periods of the active longitude rotation are determined: for EI Eri 1fd 9510, for II Peg 6fd 7066, for sigma Gem 19fd 604, for HR 7275 28fd 263. Long-term activity cycles of the stars are discovered from the analysis of the relative contribution of the two longitudes to the photometric variability. One longitude is found to be usually more active than the other at a given moment, and the change of the activity level between the longitudes is cyclic with periods of years. The switch of the activity takes a much shorter time, about a few months, similar to the ``flip-flop'' phenomenon found for FK Com stars. Moments of switching are regarded as new tracers of the activity, and total cycles, which return activity to the same longitude, are found to be for EI Eri 9.0 yr, for II Peg 9.3 yr, for sigma Gem 14.9 yr, for HR 7275 17.5 yr.

  6. GAS SURFACE DENSITY, STAR FORMATION RATE SURFACE DENSITY, AND THE MAXIMUM MASS OF YOUNG STAR CLUSTERS IN A DISK GALAXY. II. THE GRAND-DESIGN GALAXY M51

    SciTech Connect

    Gonzalez-Lopezlira, Rosa A.; Pflamm-Altenburg, Jan; Kroupa, Pavel

    2013-06-20

    We analyze the relationship between maximum cluster mass and surface densities of total gas ({Sigma}{sub gas}), molecular gas ({Sigma}{sub H{sub 2}}), neutral gas ({Sigma}{sub H{sub I}}), and star formation rate ({Sigma}{sub SFR}) in the grand-design galaxy M51, using published gas data and a catalog of masses, ages, and reddenings of more than 1800 star clusters in its disk, of which 223 are above the cluster mass distribution function completeness limit. By comparing the two-dimensional distribution of cluster masses and gas surface densities, we find for clusters older than 25 Myr that M{sub 3rd}{proportional_to}{Sigma}{sub H{sub I}{sup 0.4{+-}0.2}}, whereM{sub 3rd} is the median of the five most massive clusters. There is no correlation with{Sigma}{sub gas},{Sigma}{sub H2}, or{Sigma}{sub SFR}. For clusters younger than 10 Myr, M{sub 3rd}{proportional_to}{Sigma}{sub H{sub I}{sup 0.6{+-}0.1}} and M{sub 3rd}{proportional_to}{Sigma}{sub gas}{sup 0.5{+-}0.2}; there is no correlation with either {Sigma}{sub H{sub 2}} or{Sigma}{sub SFR}. The results could hardly be more different from those found for clusters younger than 25 Myr in M33. For the flocculent galaxy M33, there is no correlation between maximum cluster mass and neutral gas, but we have determined M{sub 3rd}{proportional_to}{Sigma}{sub gas}{sup 3.8{+-}0.3}, M{sub 3rd}{proportional_to}{Sigma}{sub H{sub 2}{sup 1.2{+-}0.1}}, and M{sub 3rd}{proportional_to}{Sigma}{sub SFR}{sup 0.9{+-}0.1}. For the older sample in M51, the lack of tight correlations is probably due to the combination of strong azimuthal variations in the surface densities of gas and star formation rate, and the cluster ages. These two facts mean that neither the azimuthal average of the surface densities at a given radius nor the surface densities at the present-day location of a stellar cluster represent the true surface densities at the place and time of cluster formation. In the case of the younger sample, even if the clusters have not yet

  7. Single-Path Sigma from a Huge Dataset in Taiwan

    NASA Astrophysics Data System (ADS)

    Sung, Chih-Hsuan; Lee, Chyi-Tyi

    2014-05-01

    Ground-motion variability, which was used in the probabilistic seismic hazard analysis (PSHA) in computing annual exceedence probability, is composed of random variability (aleatory uncertainty) and model uncertainty (epistemic uncertainty). Finding random variability of ground motions has become an important issue in PSHA, and only the random variability can be used in deriving the annual exceedence probability of ground-motion. Epistemic uncertainty will be put in the logic tree to estimate the total uncertainty of ground-motion. In the present study, we used about 18,859 records from 158 shallow earthquakes (Mw > 3.0, focal depth ≤ 35 km, each station has at least 20 records) form the Taiwan Strong-Motion Instrumentation Program (TSMIP) network to analyse the random variability of ground-motion. First, a new ground-motion attenuation model was established by using this huge data set. Second, the residuals from the median attenuation were analysed by direct observation on inter-event variability and site-specific variability. Finally, the single-path variability was found by a moving-window method on either single-earthquake residuals or single-station residuals. A variogram method was also used to find minimum variability for intra-event residuals and inter-event residuals, respectively. Results reveal that 90% of the single-path sigma σSP are ranging from 0.219 to 0.254 (ln unit) and are 58% to 64% smaller than the total sigma (σT =0.601). The single-site sigma (σSS) are also 39%-43% smaller. If we use only random variability (single-path sigma) in PSHA, then the resultant hazard level would be 28% and 25% lower than the traditional one (using total sigma) in 475-year and in 2475-year return period, respectively, in Taipei.

  8. MAXIMALLY STAR-FORMING GALACTIC DISKS. II. VERTICALLY RESOLVED HYDRODYNAMIC SIMULATIONS OF STARBURST REGULATION

    SciTech Connect

    Shetty, Rahul; Ostriker, Eve C. E-mail: ostriker@astro.umd.edu

    2012-07-20

    We explore the self-regulation of star formation using a large suite of high-resolution hydrodynamic simulations, focusing on molecule-dominated regions (galactic centers and [U]LIRGS) where feedback from star formation drives highly supersonic turbulence. In equilibrium, the total midplane pressure, dominated by turbulence, must balance the vertical weight of the interstellar medium. Under self-regulation, the momentum flux injected by feedback evolves until it matches the vertical weight. We test this flux balance in simulations spanning a wide range of parameters, including surface density {Sigma}, momentum injected per stellar mass formed (p{sub *}/m{sub *}), and angular velocity. The simulations are two-dimensional radial-vertical slices, and include both self-gravity and an external potential that helps to confine gas to the disk midplane. After the simulations reach a steady state in all relevant quantities, including the star formation rate {Sigma}{sub SFR}, there is remarkably good agreement between the vertical weight, the turbulent pressure, and the momentum injection rate from supernovae. Gas velocity dispersions and disk thicknesses increase with p{sub *}/m{sub *}. The efficiency of star formation per free-fall time at the midplane density, {epsilon}{sub ff}(n{sub 0}), is insensitive to the local conditions and to the star formation prescription in very dense gas. We measure {epsilon}{sub ff}(n{sub 0}) {approx} 0.004-0.01, consistent with low and approximately constant efficiencies inferred from observations. For {Sigma} in (100-1000) M{sub Sun} pc{sup -2}, we find {Sigma}{sub SFR} in (0.1-4) M{sub Sun} kpc{sup -2} yr{sup -1}, generally following a {Sigma}{sub SFR} {proportional_to} {Sigma}{sup 2} relationship. The measured relationships agree very well with vertical equilibrium and with turbulent energy replenishment by feedback within a vertical crossing time. These results, along with the observed {Sigma}-{Sigma}{sub SFR} relation in high

  9. Enhanced antidepressant effect of sigma(1) (sigma(1)) receptor agonists in beta(25-35)-amyloid peptide-treated mice.

    PubMed

    Urani, Alexandre; Romieu, Pascal; Roman, François J; Maurice, Tangui

    2002-08-21

    This study examined the antidepressant efficacy of the selective sigma(1) receptor agonists igmesine or PRE-084 in mice injected intracerebroventricularly (i.c.v.) with beta(25-35)-amyloid peptide and submitted to the forced swim test. Beta(25-35) peptide-injected animals developed memory deficits after 8 days contrarily to controls injected with scrambled beta(25-35) peptide or vehicle solution. In the forced swim test, the i.c.v. treatment failed to affect the immobility duration, but the antidepressant effect of the sigma(1) agonists was facilitated in beta(25-35) animals. Igmesine reduced immobility duration at 30 versus 60 mg/kg in control groups. PRE-084 decreased immobility duration at 30 and 60 mg/kg only in beta(25-35) animals. Desipramine reduced the immobility duration similarly among groups and fluoxetine appeared less potent in beta(25-35) animals. The beta(25-35) animals exhibited decreased progesterone levels in the hippocampus (-47%). The behavioural efficacy of sigma(1) agonists is known to depend on neuro(active)steroids levels synthesised by glial cells and neurones, which are affected by the beta-amyloid toxicity. This behavioural study suggests that sigma(1) agonists, due to their enhanced efficacy, may allow to alleviate the depressive symptoms associated with Alzheimer's disease.

  10. Gravitational radiation from crystalline color-superconducting hybrid stars

    SciTech Connect

    Knippel, Bettina; Sedrakian, Armen

    2009-04-15

    The interiors of high mass compact (neutron) stars may contain deconfined quark matter in a crystalline color-superconducting (CCS) state. On a basis of microscopic nuclear and quark matter equations of states we explore the internal structure of such stars in general relativity. We find that their stable sequence harbors CCS quark cores with masses M{sub core}{<=}(0.78-0.82)M{sub {center_dot}} and radii R{sub core}{<=}7 km. The CCS quark matter can support nonaxisymmetric deformations, because of its finite shear modulus, and can generate gravitational radiation at twice the rotation frequency of the star. Assuming that the CCS core is maximally strained we compute the maximal quadrupole moment it can sustain. The characteristic strain of gravitational wave emission h{sub 0} predicted by our models are compared to the upper limits obtained by the LIGO and GEO 600 detectors. The upper limits are consistent with the breaking strain of CCS matter {sigma}{<=}10{sup -4} and large pairing gaps {delta}{approx}50 MeV, or, alternatively, with {sigma}{approx}10{sup -3} and small pairing gaps {delta}{approx}15 MeV. An observationally determined value of the characteristic strain h{sub 0} can pin down the product {sigma}{delta}{sup 2}. On the theoretical side a better understanding of the breaking strain of CCS matter will be needed to predict reliably the level of the deformation of CCS quark core from first principles.

  11. Converting neutron stars into strange stars

    NASA Technical Reports Server (NTRS)

    Olinto, A. V.

    1991-01-01

    If strange matter is formed in the interior of a neutron star, it will convert the entire neutron star into a strange star. The proposed mechanisms are reviewed for strange matter seeding and the possible strange matter contamination of neutron star progenitors. The conversion process that follows seeding and the recent calculations of the conversion timescale are discussed.

  12. Reconstruction and topological characterization of the sigma factor regulatory network of Mycobacterium tuberculosis.

    PubMed

    Chauhan, Rinki; Ravi, Janani; Datta, Pratik; Chen, Tianlong; Schnappinger, Dirk; Bassler, Kevin E; Balázsi, Gábor; Gennaro, Maria Laura

    2016-03-31

    Accessory sigma factors, which reprogram RNA polymerase to transcribe specific gene sets, activate bacterial adaptive responses to noxious environments. Here we reconstruct the complete sigma factor regulatory network of the human pathogen Mycobacterium tuberculosis by an integrated approach. The approach combines identification of direct regulatory interactions between M. tuberculosis sigma factors in an E. coli model system, validation of selected links in M. tuberculosis, and extensive literature review. The resulting network comprises 41 direct interactions among all 13 sigma factors. Analysis of network topology reveals (i) a three-tiered hierarchy initiating at master regulators, (ii) high connectivity and (iii) distinct communities containing multiple sigma factors. These topological features are likely associated with multi-layer signal processing and specialized stress responses involving multiple sigma factors. Moreover, the identification of overrepresented network motifs, such as autoregulation and coregulation of sigma and anti-sigma factor pairs, provides structural information that is relevant for studies of network dynamics.

  13. Reconstruction and topological characterization of the sigma factor regulatory network of Mycobacterium tuberculosis

    PubMed Central

    Chauhan, Rinki; Ravi, Janani; Datta, Pratik; Chen, Tianlong; Schnappinger, Dirk; Bassler, Kevin E.; Balázsi, Gábor; Gennaro, Maria Laura

    2016-01-01

    Accessory sigma factors, which reprogram RNA polymerase to transcribe specific gene sets, activate bacterial adaptive responses to noxious environments. Here we reconstruct the complete sigma factor regulatory network of the human pathogen Mycobacterium tuberculosis by an integrated approach. The approach combines identification of direct regulatory interactions between M. tuberculosis sigma factors in an E. coli model system, validation of selected links in M. tuberculosis, and extensive literature review. The resulting network comprises 41 direct interactions among all 13 sigma factors. Analysis of network topology reveals (i) a three-tiered hierarchy initiating at master regulators, (ii) high connectivity and (iii) distinct communities containing multiple sigma factors. These topological features are likely associated with multi-layer signal processing and specialized stress responses involving multiple sigma factors. Moreover, the identification of overrepresented network motifs, such as autoregulation and coregulation of sigma and anti-sigma factor pairs, provides structural information that is relevant for studies of network dynamics. PMID:27029515

  14. 'Tertiary' nuclear burning - Neutron star deflagration?

    NASA Technical Reports Server (NTRS)

    Michel, F. Curtis

    1988-01-01

    A motivation is presented for the idea that dense nuclear matter can burn to a new class of stable particles. One of several possibilities is an 'octet' particle which is the 16 baryon extension of alpha particle, but now composed of a pair of each of the two nucleons, (3Sigma, Delta, and 2Xi). Such 'tertiary' nuclear burning (here 'primary' is H-He and 'secondary' is He-Fe) may lead to neutron star explosions rather than collapse to a black hole, analogous to some Type I supernovae models wherein accreting white dwarfs are pushed over the Chandrasekhar mass limit but explode rather than collapse to form neutron stars. Such explosions could possibly give gamma-ray bursts and power quasars, with efficient particle acceleration in the resultant relativistic shocks. The new stable particles themselves could possibly be the sought-after weakly interacting, massive particles (WIMPs) or 'dark' matter.

  15. Exceptional Stars

    NASA Astrophysics Data System (ADS)

    Kulkarni, S. R.; Hansen, B.; van Kerkwijk, M.; Phinney, E. S.

    2005-12-01

    As part of our Interdisciplinary Scientist effort (PI, Kulkarni) for the Space Interferometry Mission (SIM) we proposed an investigation with SIM of a number of exceptional stars. With SIM we plan to observe dozens of nearby white dwarfs and search for planets surviving the evolution away from the main sequence as well as (newly formed) planets formed in the circumbinary disks of post-AGB binaries or as a result of white dwarf mergers. We propose to measure the proper motion of a sample of X-ray binaries and Be star binaries with the view of understanding the originof high latitude objects and inferring natal kicks and pre-supernova orbits. We plan to observe several compact object binaries to determine the mass of the compact star. Of particular importance is the proposed observation of SS 433 (for which we propose to use the spectrometer on SIM to measure the proper motion of the emission line clumps embedded in the relativistic jets). Separately we are investigating the issue of frame tie between SIM and the ecliptic frame (by observing binary millisecond pulsars with SIM; the position of these objects is very well determined by pulsar timing) and the degree to which highly precise visibility amplitude measurements can be inverted to infer binary parameters.

  16. Six Sigma: not for the faint of heart.

    PubMed

    Benedetto, Anthony R

    2003-01-01

    Six Sigma is an excellent quality and performance improvement tool. Like any tool, the results of using it are highly dependent on whether you use it with competence and on the right problem. This article will help you decide if your problem is well-suited for a Six Sigma approach and will suggest the optimum approach for planning and implementing Six Sigma methodology. Performance improvement methods can be grouped into two broad categories, based on the problem to be addressed. When the problem is relatively minor and localized, "evolutionary" methods may be suitable (e.g., quality circles, problem-solving staff meetings, continuous quality improvement [CQI], total quality management [TQM]). These tools work best when modest incremental improvements are sought, when major process redesign is not thought to be necessary, and when the avoidance of workplace disruption is desired. Reengineering and Six Sigma are the best-known examples of the "revolutionary" performance improvement methods. These methods should be used when major (drastic, do or die, etc.) improvements are needed. Problems that cross departmental boundaries need these methods. When a process is so dysfunctional that you feel like you need to tear up the standard operating procedure (SOP) and start all over again, you need a revolutionary method. A Six Sigma project requires a major expenditure of money and employee time, and a willingness to make some hard decisions about jobs, employee retention and relationships among stakeholders. An institution's culture should be considered as part of the decision about using Six Sigma. If the institution has a history of making data-driven decisions, or at least has displayed openness to operating in that manner, Six Sigma has a good chance of success. A radiology-driven Six Sigma project should not be undertaken until a comprehensive written description of the scope of the project is approved by the radiology department leadership team and by the appropriate

  17. Six Sigma: not for the faint of heart.

    PubMed

    Benedetto, Anthony R

    2003-01-01

    Six Sigma is an excellent quality and performance improvement tool. Like any tool, the results of using it are highly dependent on whether you use it with competence and on the right problem. This article will help you decide if your problem is well-suited for a Six Sigma approach and will suggest the optimum approach for planning and implementing Six Sigma methodology. Performance improvement methods can be grouped into two broad categories, based on the problem to be addressed. When the problem is relatively minor and localized, "evolutionary" methods may be suitable (e.g., quality circles, problem-solving staff meetings, continuous quality improvement [CQI], total quality management [TQM]). These tools work best when modest incremental improvements are sought, when major process redesign is not thought to be necessary, and when the avoidance of workplace disruption is desired. Reengineering and Six Sigma are the best-known examples of the "revolutionary" performance improvement methods. These methods should be used when major (drastic, do or die, etc.) improvements are needed. Problems that cross departmental boundaries need these methods. When a process is so dysfunctional that you feel like you need to tear up the standard operating procedure (SOP) and start all over again, you need a revolutionary method. A Six Sigma project requires a major expenditure of money and employee time, and a willingness to make some hard decisions about jobs, employee retention and relationships among stakeholders. An institution's culture should be considered as part of the decision about using Six Sigma. If the institution has a history of making data-driven decisions, or at least has displayed openness to operating in that manner, Six Sigma has a good chance of success. A radiology-driven Six Sigma project should not be undertaken until a comprehensive written description of the scope of the project is approved by the radiology department leadership team and by the appropriate

  18. ARCHEOLOGY OF AN ANCIENT STAR

    SciTech Connect

    Fuhrmann, K.; Chini, R.; Haas, M.; Hackstein, M.; Ramolla, M.; Bernkopf, J.

    2012-12-20

    We report on the bright and late F-type star HR 3138, which, with respect to its chemistry in the [Mg/H]-[Fe/Mg] abundance plane, we identify as an old Population II member. Evolutionary tracks are, however, in conflict with this finding and instead imply an age of only {tau} = 5.6{sup -1.8}{sub +{sub 2.2}} Gyr (2{sigma}) for HR 3138. We discuss this controversy in light of existing high-precision radial velocity surveys that mostly exclude the case of a blue straggler primary and a white dwarf secondary. While it is realized that a stellar merger can principally solve the issue and there is indeed observational evidence for mass accretion on HR 3138 from the absence of lithium in its photosphere, we also consider the interesting circumstance that HR 3138 lies in the direction to the 350 pc distant, young open cluster NGC 2516. We point to the possibility that the progenitor cloud of this cluster may likewise account for former mass accretion and we argue in particular for a dynamical friction with this cloud as a plausible cause for the strikingly common Galactic rotational velocity of the field star and open cluster.

  19. Updated Radio Sigma-D Relation for Galactic Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Pavlovic, M. Z.; Dobardzic, A.; Vukotic, B.; Urosevic, D.

    2014-12-01

    We present the updated empirical radio surface-brightness-to-diameter (Sigma - D) relation for supernova remnants (SNRs) in our Galaxy. Our original calibration sample of Galactic SNRs with independently determined distances (Pavlovic et al. 2013, hereafter Paper I) is reconsidered and updated with data which became available in the past two years. The orthogonal fitting procedure and probability-density-function-based (PDF) method are applied to the calibration sample in the log Sigma - log D plane. Non-standard orthogonal regression keeps the Sigma-D and D-Sigma relations invariant within estimated uncertainties. Our previous Monte Carlo simulations verified that the slopes of the empirical Sigma-D relation should be determined by using the orthogonal regression, because of its good performances for data sets with severe scatter. The updated calibration sample contains 65 shell SNRs. 6 new Galactic SNRs are added to the sample from Paper I, one is omitted and distances are changed for 10 SNRs. The slope derived is here slightly steeper (β ≈ 5.2) than the Sigma-D slope in Paper I (β ≈ 4.8). The PDF method relies on data points density maps which can provide more reliable calibrations that preserve more information contained in the calibration sample. We estimate distances to five new faint Galactic SNRs discovered for the first time by Canadian Galactic Plane Survey, and obtained distances of 2.3, 4.0, 1.3, 2.9 and 4.7 kiloparsecs for G108.5+11.0, G128.5+2.6, G149.5+3.2, G150.8+3.8 and G160.1-1.1, respectively. The updated empirical relation is used to estimate distances of 160 shell Galactic SNRs and new results change their distance scales up to 15 per cent, compared to the results from Paper I. The PDF calculation can provide even few times higher or lower values in comparison with the orthogonal fit, as it uses a totally different approach. However, on average, this difference is 32, 24 and 18 per cent for mode, median and mean distances.

  20. Target space pseudoduality in supersymmetric sigma models on symmetric spaces

    NASA Astrophysics Data System (ADS)

    Sarisaman, Mustafa

    We discuss the target space pseudoduality in supersymmetric sigma models on symmetric spaces. We first consider the case where sigma models based on real compact connected Lie groups of the same dimensionality and give examples using three dimensional models on target spaces. We show explicit construction of nonlocal conserved currents on the pseudodual manifold. We then switch the Lie group valued pseudoduality equations to Lie algebra valued ones, which leads to an infinite number of pseudoduality equations. We obtain an infinite number of conserved currents on the tangent bundle of the pseudo-dual manifold. Since pseudoduality imposes the condition that sigma models pseudodual to each other are based on symmetric spaces with opposite curvatures (i.e. dual symmetric spaces), we investigate pseudoduality transformation on the symmetric space sigma models in the third chapter. We see that there can be mixing of decomposed spaces with each other, which leads to mixings of the following expressions. We obtain the pseudodual conserved currents which are viewed as the orthonormal frame on the pullback bundle of the tangent space of G˜ which is the Lie group on which the pseudodual model based. Hence we obtain the mixing forms of curvature relations and one loop renormalization group beta function by means of these currents. In chapter four, we generalize the classical construction of pseudoduality transformation to supersymmetric case. We perform this both by component expansion method on manifold M and by orthonormal coframe method on manifold SO( M). The component method produces the result that pseudoduality transformation is not invertible at all points and occurs from all points on one manifold to only one point where riemann normal coordinates valid on the second manifold. Torsion of the sigma model on M must vanish while it is nonvanishing on M˜, and curvatures of the manifolds must be constant and the same because of anticommuting grassmann numbers. We obtain

  1. The {sigma} phase formation in annealed UNS S31803 duplex stainless steel: Texture aspects

    SciTech Connect

    Souza, C.M. Abreu, H.F.G.; Tavares, S.S.M.; Rebello, J.M.A.

    2008-09-15

    The influence of sigma phase precipitation on the texture of austenite in a duplex stainless steel UNS S31803 was investigated. Sigma phase quantification was precisely performed by electron backscattered scanning diffraction (EBSD) for some conditions. It was found that the increase of the sigma phase precipitation enhances the amount of Brass texture in the austenite phase.

  2. Functional assays to define agonists and antagonists of the sigma-2 receptor

    PubMed Central

    Zeng, Chenbo; Rothfuss, Justin M.; Zhang, Jun; Vangveravong, Suwanna; Chu, Wenhua; Li, Shihong; Tu, Zhude; Xu, Jinbin; Mach, Robert H.

    2014-01-01

    The sigma-2 receptor has been identified as a biomarker in proliferating tumors. Up to date there is no well-established functional assay for defining sigma-2 agonists and antagonists. Many sigma-2 ligands with diverse structures have been shown to induce cell death in a variety of cancer cells by triggering caspase-dependent and independent apoptosis. Therefore, in the current study, we used the cell viability assay and the caspase-3 activity assay to determine sigma-2 agonists and antagonists. Three classes of sigma-2 ligands developed in our laboratory were evaluated for their potency to induce cell death in two tumor cell lines, mouse breast cancer cell line EMT-6 and human melanoma cell line MDA-MB-435. The data showed that the EC50 values of the sigma-2 ligands using the cell viability assay ranged from 11.4 μM to >200 μM, which were comparable with the EC50 values obtained using the caspase-3 assay. Based on the cytotoxicity of a sigma-2 ligand relative to that of siramesine, a commonly accepted sigma-2 agonist, we have categorized our sigma-2 ligands into agonists, partial agonists, and antagonists. The establishment of functional assays for defining sigma-2 agonists and antagonists will facilitate functional characterization of sigma-2 receptor ligands and sigma-2 receptors. PMID:24333652

  3. A Framework for Six Sigma Project Selection in Higher Educational Institutions, Using a Weighted Scorecard Approach

    ERIC Educational Resources Information Center

    Holmes, Monica C.; Jenicke, Lawrence O.; Hempel, Jessica L.

    2015-01-01

    Purpose: This paper discusses the importance of the Six Sigma selection process, describes a Six Sigma project in a higher educational institution and presents a weighted scorecard approach for project selection. Design/Methodology/Approach: A case study of the Six Sigma approach being used to improve student support at a university computer help…

  4. Inhibition of tumor cell growth by Sigma1 ligand mediated translational repression

    SciTech Connect

    Kim, Felix J.; Schrock, Joel M.; Spino, Christina M.; Marino, Jacqueline C.; Pasternak, Gavril W.

    2012-09-21

    Highlights: Black-Right-Pointing-Pointer Sigma1 ligand treatment mediates decrease in tumor cell mass. Black-Right-Pointing-Pointer Identification of a Sigma1 ligand with reversible translational repressor actions. Black-Right-Pointing-Pointer Demonstration of a role for Sigma1 in cellular protein synthesis. -- Abstract: Treatment with sigma1 receptor (Sigma1) ligands can inhibit cell proliferation in vitro and tumor growth in vivo. However, the cellular pathways engaged in response to Sigma1 ligand treatment that contribute to these outcomes remain largely undefined. Here, we show that treatment with putative antagonists of Sigma1 decreases cell mass. This effect corresponds with repressed cap-dependent translation initiation in multiple breast and prostate cancer cell lines. Sigma1 antagonist treatment suppresses phosphorylation of translational regulator proteins p70S6K, S6, and 4E-BP1. RNAi-mediated knockdown of Sigma1 also results in translational repression, consistent with the effects of antagonist treatment. Sigma1 antagonist mediated translational repression and decreased cell size are both reversible. Together, these data reveal a role for Sigma1 in tumor cell protein synthesis, and demonstrate that small molecule Sigma1 ligands can be used as modulators of protein translation.

  5. THE MAGNESIUM ISOTOPOLOGUES OF MgH IN THE A {sup 2}{Pi}-X {sup 2}{Sigma}{sup +} SYSTEM

    SciTech Connect

    Hinkle, Kenneth H.; Wallace, Lloyd; Ram, Ram S.; Bernath, Peter F.; Sneden, Christopher; Lucatello, Sara E-mail: wallace@noao.edu E-mail: pbernath@odu.edu E-mail: sara.lucatello@oapd.inaf.it

    2013-08-15

    Using laboratory hollow cathode spectra we have identified lines of the less common magnesium isotopologues of MgH, {sup 25}MgH and {sup 26}MgH, in the A {sup 2}{Pi}-X {sup 2}{Sigma}{sup +} system. Based on the previous analysis of {sup 24}MgH, molecular lines have been measured and molecular constants derived for {sup 25}MgH and {sup 26}MgH. Term values and linelists, in both wavenumber and wavelength units, are presented. The A {sup 2}{Pi}-X {sup 2}{Sigma}{sup +} system of MgH is important for measuring the magnesium isotope ratios in stars. Examples of analysis using the new linelists to derive the Mg isotope ratio in a metal poor dwarf and giant are shown.

  6. Transcriptional organization and in vivo role of the Escherichia coli rsd gene, encoding the regulator of RNA polymerase sigma D.

    PubMed

    Jishage, M; Ishihama, A

    1999-06-01

    The regulator of sigma D (Rsd) was identified as an RNA polymerase sigma70-associated protein in stationary-phase Escherichia coli with the inhibitory activity of sigma70-dependent transcription in vitro (M. Jishage and A. Ishihama, Proc. Natl. Acad. Sci. USA 95:4953-4958, 1998). Primer extension analysis of rsd mRNA indicated the presence of two promoters, sigmaS-dependent P1 and sigma70-dependent P2 with the gearbox sequence. To get insight into the in vivo role of Rsd, the expression of a reporter gene fused to either the sigma70- or sigmaS-dependent promoter was analyzed in the absence of Rsd or the presence of overexpressed Rsd. In the rsd null mutant, the sigma70- and sigmaS-dependent gene expression was increased or decreased, respectively. On the other hand, the sigma70- or sigmaS-dependent transcription was reduced or enhanced, respectively, after overexpression of Rsd. The repression of the sigmaS-dependent transcription in the rsd mutant is overcome by increased production of the sigmaS subunit. Together these observations support the prediction that Rsd is involved in replacement of the RNA polymerase sigma subunit from sigma70 to sigmaS during the transition from exponential growth to the stationary phase.

  7. Digital Pixel Sensor Array with Logarithmic Delta-Sigma Architecture

    PubMed Central

    Mahmoodi, Alireza; Li, Jing; Joseph, Dileepan

    2013-01-01

    Like the human eye, logarithmic image sensors achieve wide dynamic range easily at video rates, but, unlike the human eye, they suffer from low peak signal-to-noise-and-distortion ratios (PSNDRs). To improve the PSNDR, we propose integrating a delta-sigma analog-to-digital converter (ADC) in each pixel. An image sensor employing this architecture is designed, built and tested in 0.18 micron complementary metal-oxide-semiconductor (CMOS) technology. It achieves a PSNDR better than state-of-the-art logarithmic sensors and comparable to the human eye. As the approach concerns an array of many ADCs, we use a small-area low-power delta-sigma design. For scalability, each pixel has its own decimator. The prototype is compared to a variety of other image sensors, linear and nonlinear, from industry and academia. PMID:23959239

  8. Pseudo-random number generator for the Sigma 5 computer

    NASA Technical Reports Server (NTRS)

    Carroll, S. N.

    1983-01-01

    A technique is presented for developing a pseudo-random number generator based on the linear congruential form. The two numbers used for the generator are a prime number and a corresponding primitive root, where the prime is the largest prime number that can be accurately represented on a particular computer. The primitive root is selected by applying Marsaglia's lattice test. The technique presented was applied to write a random number program for the Sigma 5 computer. The new program, named S:RANDOM1, is judged to be superior to the older program named S:RANDOM. For applications requiring several independent random number generators, a table is included showing several acceptable primitive roots. The technique and programs described can be applied to any computer having word length different from that of the Sigma 5.

  9. Suppression of the {Lambda}-{Sigma} coupling in nuclear matter

    SciTech Connect

    Bodmer, A.R.; Usmani, Q.N.

    1995-08-01

    We initiated a study of the modification of the coupling of the {Lambda}N to the {Sigma}N channel in nuclear matter with the Fermi hypernetted-chain variational approach. This modification of the {Lambda}N-{Sigma}N coupling is a central problem in hypernuclear physics and is related closely to the strongly repulsive three-body forces which are needed to account for hypernuclear binding energies. All earlier calculations have only considered this problem in the so-called G-matrix approximation which neglects important higher-order effects. An important result of this work will be a better understanding of the density dependence of {Lambda} binding in nuclear matter, which can then be tested in the calculation of the {Lambda} single-particle energies.

  10. Is health care ready for Six Sigma quality?

    PubMed

    Chassin, M R

    1998-01-01

    Serious, widespread problems exist in the quality of U.S. health care: too many patients are exposed to the risks of unnecessary services; opportunities to use effective care are missed; and preventable errors lead to injuries. Advanced practitioners of industrial quality management, like Motorola and General Electric, have committed themselves to reducing the frequency of defects in their business processes to fewer than 3.4 per million, a strategy known as Six Sigma Quality. In health care, quality problems frequently occur at rates of 20 to 50 percent, or 200,000 to 500,000 per million. In order to approach Six Sigma levels of quality, the health care sector must address the underlying causes of error and make important changes: adopting new educational models; devising strategies to increase consumer awareness; and encouraging public and private investment in quality improvement.

  11. Exploring pseudoscalar meson scattering in linear sigma models

    NASA Astrophysics Data System (ADS)

    Black (Speaker), Deirdre; Fariborz, Amir H.; Moussa, Sherif; Nasri, Salah; Schechter, Joseph

    2001-11-01

    The three flavor linear sigma model is studied as a toy model for understanding the role of possible light scalar mesons in the ππ, πK and πɛ elastic scattering channels. We unitarize tree level amplitudes using the K-matrix prescription and, with a sufficiently general model, obtain reasonable fits to the experimental data. The effect of unitarization is very important and leads to the emergence of a nonet of light scalars, with masses below 1 GeV. We compare with a scattering treatment using a more general non-linear sigma model approach and also comment briefly upon how our results fit in with the scalar meson puzzle. .

  12. Sigma term and strangeness content of octet baryons

    NASA Astrophysics Data System (ADS)

    Dürr, S.; Fodor, Z.; Hemmert, T.; Hoelbling, C.; Frison, J.; Katz, S. D.; Krieg, S.; Kurth, T.; Lellouch, L.; Lippert, T.; Portelli, A.; Ramos, A.; Schäfer, A.; Szabó, K. K.

    2012-01-01

    By using lattice QCD computations we determine the sigma terms and strangeness content of all octet baryons by means of an application of the Hellmann-Feynman theorem. In addition to polynomial and rational expressions for the quark-mass dependence of octet members, we use SU(3) covariant baryon chiral perturbation theory to perform the extrapolation to the physical up and down quark masses. Our Nf=2+1 lattice ensembles include pion masses down to about 190 MeV in large volumes (MπL≳4), and three values of the lattice spacing. Our main results are the nucleon sigma term σπN=39(4)(-7+18) and the strangeness content yN=0.20(7)(-17+13). Under the assumption of validity of covariant baryon χPT in our range of masses one finds yN=0.276(77)(-62+90).

  13. The moduli space of superconformal instantons in sigma models

    SciTech Connect

    Monastyrsky, M.I. ); Natanzon, S.M. )

    1991-06-21

    In this paper, an approach to instantons in supersymmetrical 2-dimensional sigma models is discussed. In this approach superinstantons are characterized as the superconformal maps of a physical space into the isotopic (target) space. The authors consider a special case of the supersphere with punctures. New topological invariants as the number of the so-called fermionic points appear in this case. The authors also analyze the structure of the moduli space of superinstantons within this framework.

  14. The innovative use of Six Sigma in home care.

    PubMed

    Elberfeld, Adrienne; Bennis, Sandra; Ritzius, Jeannie; Yhlen, David

    2007-01-01

    The Prospective Payment System had significant impact on home healthcare agencies throughout the nation. Virtua Home Care, located in Southern New Jersey, realized the need for process improvement in order to remain viable. Six Sigma was introduced to the agency and the Define, Measure, Analyze, Improve, and Control processes were initiated to achieve sustainable results, and within 9 months, Virtua Home Care improved regulatory compliance, experienced a deficiency-free survey, and recognized a 1.2 million dollars financial gain.

  15. Linear Sigma Model Toolshed for D-brane Physics

    SciTech Connect

    Hellerman, Simeon

    2001-08-23

    Building on earlier work, we construct linear sigma models for strings on curved spaces in the presence of branes. Our models include an extremely general class of brane-worldvolume gauge field configurations. We explain in an accessible manner the mathematical ideas which suggest appropriate worldsheet interactions for generating a given open string background. This construction provides an explanation for the appearance of the derived category in D-brane physic complementary to that of recent work of Douglas.

  16. Towards Resolving the Crab Sigma-Problem: A Linear Accelerator?

    NASA Technical Reports Server (NTRS)

    Contopoulos, Ioannis; Kazanas, Demosthenes; White, Nicholas E. (Technical Monitor)

    2002-01-01

    Using the exact solution of the axisymmetric pulsar magnetosphere derived in a previous publication and the conservation laws of the associated MHD flow, we show that the Lorentz factor of the outflowing plasma increases linearly with distance from the light cylinder. Therefore, the ratio of the Poynting to particle energy flux, generically referred to as sigma, decreases inversely proportional to distance, from a large value (typically approx. greater than 10(exp 4)) near the light cylinder to sigma approx. = 1 at a transition distance R(sub trans). Beyond this distance the inertial effects of the outflowing plasma become important and the magnetic field geometry must deviate from the almost monopolar form it attains between R(sub lc), and R(sub trans). We anticipate that this is achieved by collimation of the poloidal field lines toward the rotation axis, ensuring that the magnetic field pressure in the equatorial region will fall-off faster than 1/R(sup 2) (R being the cylindrical radius). This leads both to a value sigma = a(sub s) much less than 1 at the nebular reverse shock at distance R(sub s) (R(sub s) much greater than R(sub trans)) and to a component of the flow perpendicular to the equatorial component, as required by observation. The presence of the strong shock at R = R(sub s) allows for the efficient conversion of kinetic energy into radiation. We speculate that the Crab pulsar is unique in requiring sigma(sub s) approx. = 3 x 10(exp -3) because of its small translational velocity, which allowed for the shock distance R(sub s) to grow to values much greater than R(sub trans).

  17. A symmetric approach to the massive nonlinear sigma model

    DOE PAGESBeta

    Ferrari, Ruggero

    2011-09-28

    In the present study we extend to the massive case the procedure of divergences subtraction, previously introduced for the massless nonlinear sigma model (D = 4). Perturbative expansion in the number of loops is successfully constructed. The resulting theory depends on the Spontaneous Symmetry Breaking parameter v, on the mass m and on the radiative correction parameter Λ. Fermions are not considered in the present work. SU(2) Ⓧ SU(2) is the group used.

  18. Highly excited {Sigma}{sup -} states of molecular hydrogen

    SciTech Connect

    Argoubi, F.; Bezzaouia, S.; Oueslati, H.; Telmini, M.; Jungen, Ch.

    2011-05-15

    We report calculations of H{sub 2} {Sigma}{sup -} states using a variational R-matrix approach combined with multichannel quantum defect theory. Several Rydberg series converging to the 2p{pi} state of the H{sub 2}{sup +} ion core are established and their mutual channel interactions characterized. The influence of the external electron on the chemical bond is found to be particularly strong in these electronically and chemically weakly bound states.

  19. A community hospital's journey into Lean Six Sigma.

    PubMed

    Stuenkel, Kurt; Faulkner, Taunya

    2009-01-01

    The implementation of Lean Six Sigma and 100-day workouts throughout the 304-bed Floyd Medical Center community hospital organization has led to sustainable results and a marked change in culture. The organization-wide learning of such an effort is deep and intehse, and to remain focused and successful it must be a priority of top management. The workout methodology can assist the organization to carry projects to completion and to achieve rapid implementation of desired improvements.

  20. Thermal stabilization of superconducting sigma strings and their drum vortons

    NASA Astrophysics Data System (ADS)

    Carter, Brandon; Brandenberger, Robert H.; Davis, Anne-Christine

    2002-05-01

    We discuss various issues related to stabilized embedded strings in a thermal background. In particular, we demonstrate that such strings will generically become superconducting at moderately low temperatures, thus enhancing their stability. We then present a new class of defects-drum vortons-which arise when a small symmetry breaking term is added to the potential. We display these points within the context of the O(4) sigma model, relevant for hadrodynamics below the QCD scale. This model admits ``embedded defects'' (topological defect configurations of a simpler-in this case O(2) symmetric-model obtained by imposing an embedding constraint) that are unstable in the full model at zero temperature, but that can be stabilized (by electromagnetic coupling to photons) in a thermal gas at moderately high termperatures. It is shown here that below the embedded defect stabilization threshold, there will still be stabilized cosmic string defects. However, they will not be of the symmetric embedded vortex type, but of an ``asymmetric'' vortex type, and are automatically superconducting. In the presence of weak symmetry breaking terms, such as arise naturally when using the O(4) model for hadrodynamics, the strings become the boundary of a new kind of cosmic sigma membrane, with tension given by the pion mass. The string current would then make it possible for a loop to attain a (classically) stable equilibrium state that differs from an ``ordinary'' vorton state by the presence of a sigma membrane stretched across it in a drum-like configuration. Such defects will however be entirely destabilized if the symmetry breaking is too strong, as is found to be the case-due to the rather large value of the pion mass-in the hadronic application of the O(4) sigma model.

  1. MODELING THE STAR-FORMING UNIVERSE AT z = 2: IMPACT OF COLD ACCRETION FLOWS

    SciTech Connect

    Khochfar, Sadegh; Silk, Joseph

    2009-07-20

    We present results of a semianalytic model (SAM) that includes cold accretion and a porosity-based prescription for star formation. We can recover the puzzling observational results of low V/{sigma} seen in various massive disk or disk-like galaxies, if we allow 18% of the accretion energy from cold flows to drive turbulence in gaseous disks at z = 2. The increase of gas mass through cold flows is by itself not sufficient to increase the star formation rate sufficiently to recover the number density of M-dot{sub *}>120 M{sub odot} yr{sup -1} galaxies in our model. In addition, it is necessary to increase the star formation efficiency. This can be achieved naturally in the porosity model, where star formation efficiency scales {proportional_to}{sigma}, which scales as cloud velocity dispersion. As cold accretion is the main driver for gas velocity dispersion in our model, star formation efficiency parallels cold accretion rates and allows fast conversion into stars. At z {approx} 2, we find a space density 10{sup -4} Mpc{sup -3} in star-forming galaxies with M-dot{sub *}>120 M{sub odot} yr{sup -1}, in better agreement than earlier estimates from SAMs. However, the fundamental relation between M-dot{sub *} and M {sub *} is still offset from the observed relation, indicating the need for possibly more efficient star formation at high-z perhaps associated with a role for active galactic nucleus (AGN) triggering.

  2. Note on a sigma model connection with instanton dynamics

    SciTech Connect

    Fariborz, Amir H.

    2008-05-01

    It is well known that the instanton approach to QCD generates an effective term which looks like a three-flavor determinant of quark bilinears. This has the right behavior to explain the unusual mass and mixing of the {eta}(958) meson, as is often simply illustrated with the aid of a linear SU(3) sigma model. It is less well known that the instanton analysis generates another term which has the same transformation property but does not have a simple interpretation in terms of this usual linear sigma model. Here we point out that this term has an interpretation in a generalized linear sigma model containing two chiral nonets. The second chiral nonet is taken to correspond to mesons having two quarks and two antiquarks in their makeup. The generalized model seems to be useful for learning about the spectrum of low-lying scalar mesons which have been emerging in the last few years. The physics of the new term is shown to be related to the properties of an excited {eta}{sup '} state present in the generalized model and for which there are some experimental candidates.

  3. Small-area decimators for delta-sigma video sensors

    NASA Astrophysics Data System (ADS)

    Azabache Villar, Erika; Skorka, Orit; Joseph, Dileepan

    2014-04-01

    A delta-sigma, or sigma-delta, analog-to-digital converter (ADC) comprises both a modulator, which implements oversampling and noise shaping, and a decimator, which implements low-pass filtering and downsampling. Whereas these ADCs are ubiquitous in audio applications, their usage in video applications is emerging. Because of oversampling, it is preferable to integrate delta-sigma ADCs at the pixel level of megapixel video sensors. Moreover, with pixel-level applications, area usage per ADC is much more important than with chip-level applications, where there is only one or a few ADCs per chip. Recently, a small-area decimator was presented that is suitable for pixel-level applications. However, though the pixel-level design is small enough for invisible-band video sensors, it is too large for visible-band ones. As shown here, nanoscale CMOS processes offer a solution to this problem. Given constant specifications, small-area decimators are designed, simulated, and laid out, full custom, for 180, 130, and 65nm standard CMOS processes. Area usage of the whole decimator is analyzed to establish a roadmap for the design and demonstrate that it could be competitive compared to other digital pixel sensors, based on Nyquist-rate ADCs, that are being commercialized.

  4. Sigma and opioid receptors in human brain tumors

    SciTech Connect

    Thomas, G.E.; Szuecs, M.; Mamone, J.Y.; Bem, W.T.; Rush, M.D.; Johnson, F.E.; Coscia, C.J. )

    1990-01-01

    Human brain tumors and nude mouse-borne human neuroblastomas and gliomas were analyzed for sigma and opioid receptor content. Sigma binding was assessed using ({sup 3}H) 1, 3-di-o-tolylguanidine (DTG), whereas opioid receptor subtypes were measured with tritiated forms of the following: {mu}, (D-ala{sup 2}, mePhe{sup 4}, gly-ol{sup 5}) enkephalin (DAMGE); {kappa}, ethylketocyclazocine (EKC) or U69,593; {delta}, (D-pen{sup 2}, D-pen{sup 5}) enkephalin (DPDPE) or (D-ala{sup 2}, D-leu{sup 5}) enkephalin (DADLE) with {mu} suppressor present. Binding parameters were estimated by homologous displacement assays followed by analysis using the LIGAND program. Sigma binding was detected in 15 of 16 tumors examined with very high levels found in a brain metastasis from an adenocarcinoma of lung and a human neuroblastoma (SK-N-MC) passaged in nude mice. {kappa} opioid receptor binding was detected in 4 of 4 glioblastoma multiforme specimens and 2 of 2 human astrocytoma cell lines tested but not in the other brain tumors analyzed.

  5. Sigma virus and male reproductive success in Drosophila melanogaster

    PubMed Central

    Pattanaik, Swetapadma; Johnson, Laura; Matos, Luis F.; Brusini, Jérémie; Wayne, Marta L.

    2016-01-01

    The risk of disease transmission can affect female mating rate, and thus sexual conflict. Furthermore, the interests of a sexually transmitted organism may align or diverge with those of either sex, potentially making the disease agent a third participant in the sexual arms race. In Drosophila melanogaster, where sexual conflict over female mating rate is well established, we investigated how a common, non-lethal virus (sigma virus) might affect this conflict. We gave uninfected females the opportunity to copulate twice in no-choice trials: either with two uninfected males, or with one male infected with sigma virus followed by an uninfected male. We assessed whether females respond behaviorally to male infection, determined whether male infection affects either female or male reproductive success, and measured offspring infection rates. Male infection status did not influence time to copulation, or time to re-mating. However, male infection did affect male reproductive success: first males sired a significantly greater proportion of offspring, as well as more total offspring, when they were infected with sigma virus. Thus viral infection may provide males an advantage in sperm competition, or, possibly, females may preferentially use infected sperm. We found no clear costs of infection in terms of offspring survival. Viral reproductive success (the number of infected offspring) was strongly correlated with male reproductive success. Further studies are needed to demonstrate whether virus-induced changes in reproductive success affect male and female lifetime fitness, and whether virus-induced changes are under male, female, or viral control.

  6. Sigma models for genuinely non-geometric backgrounds

    NASA Astrophysics Data System (ADS)

    Chatzistavrakidis, Athanasios; Jonke, Larisa; Lechtenfeld, Olaf

    2015-11-01

    The existence of genuinely non-geometric backgrounds, i.e. ones without geometric dual, is an important question in string theory. In this paper we examine this question from a sigma model perspective. First we construct a particular class of Courant algebroids as protobialgebroids with all types of geometric and non-geometric fluxes. For such structures we apply the mathematical result that any Courant algebroid gives rise to a 3D topological sigma model of the AKSZ type and we discuss the corresponding 2D field theories. It is found that these models are always geometric, even when both 2-form and 2-vector fields are neither vanishing nor inverse of one another. Taking a further step, we suggest an extended class of 3D sigma models, whose world volume is embedded in phase space, which allow for genuinely non-geometric backgrounds. Adopting the doubled formalism such models can be related to double field theory, albeit from a world sheet perspective.

  7. Precision measurement of the {Sigma}{sup 0} hyperon mass

    SciTech Connect

    Wang, M.H.L.S.; Hartouni, E.P.; Kreisler, M.N.

    1998-02-17

    The research that is described in this paper is part of a program to study strong interaction mechanisms in proton proton collisions. The program consists of two experiments: Brookhaven E766 in which we studied the reactions pp {yields} p+ all charged particles with 27.5 GeV/c incident protons and Fermilab E690 in which we studied the reactions pp {yields} p+ all charged particles with 800 GeV/c incident protons. In these experiments, we employed state-of-the-art data acquisition sys- tems and acquired large samples of data: at Brookhaven we amassed 300 million high multiplicity events and at Fermilab, 5.5 billion events. Our uncertainty in the {Sigma}{sup 0} mass is more than 7 times smaller than the best previous result and was based on 16 times the statistics. Likewise, the {Sigma}{sup 0} - {Lambda}{sup 0} mass difference is more than 14 times more accurate than the previous best result. Finally, we note that this measurement is the first direct measurement of the {Sigma}{sup 0} mass.

  8. Binary stars.

    PubMed

    Paczynacuteski, B

    1984-07-20

    Most stars in the solar neighborhood are either double or multiple systems. They provide a unique opportunity to measure stellar masses and radii and to study many interesting and important phenomena. The best candidates for black holes are compact massive components of two x-ray binaries: Cygnus X-1 and LMC X-3. The binary radio pulsar PSR 1913 + 16 provides the best available evidence for gravitational radiation. Accretion disks and jets observed in close binaries offer a very good testing ground for models of active galactic nuclei and quasars.

  9. Binary stars.

    PubMed

    Paczynacuteski, B

    1984-07-20

    Most stars in the solar neighborhood are either double or multiple systems. They provide a unique opportunity to measure stellar masses and radii and to study many interesting and important phenomena. The best candidates for black holes are compact massive components of two x-ray binaries: Cygnus X-1 and LMC X-3. The binary radio pulsar PSR 1913 + 16 provides the best available evidence for gravitational radiation. Accretion disks and jets observed in close binaries offer a very good testing ground for models of active galactic nuclei and quasars. PMID:17749544

  10. INSIGHTS INTO PRE-ENRICHMENT OF STAR CLUSTERS AND SELF-ENRICHMENT OF DWARF GALAXIES FROM THEIR INTRINSIC METALLICITY DISPERSIONS

    SciTech Connect

    Leaman, Ryan

    2012-12-01

    Star clusters are known to have smaller intrinsic metallicity spreads than dwarf galaxies due to their shorter star formation timescales. Here we use individual spectroscopic [Fe/H] measurements of stars in 19 Local Group dwarf galaxies, 13 Galactic open clusters, and 49 globular clusters to show that star cluster and dwarf galaxy linear metallicity distributions are binomial in form, with all objects showing strong correlations between their mean linear metallicity Z-bar and intrinsic spread in metallicity {sigma}(Z){sup 2}. A plot of {sigma}(Z){sup 2} versus Z-bar shows that the correlated relationships are offset for the dwarf galaxies from the star clusters. The common binomial nature of these linear metallicity distributions can be explained with a simple inhomogeneous chemical evolution model, where the star cluster and dwarf galaxy behavior in the {sigma}(Z){sup 2}- Z-bar diagram is reproduced in terms of the number of enrichment events, covering fraction, and intrinsic size of the enriched regions. The inhomogeneity of the self-enrichment sets the slope for the observed dwarf galaxy {sigma}(Z){sup 2}- Z-bar correlation. The offset of the star cluster sequence from that of the dwarf galaxies is due to pre-enrichment, and the slope of the star cluster sequence represents the remnant signature of the self-enriched history of their host galaxies. The offset can be used to separate star clusters from dwarf galaxies without a priori knowledge of their luminosity or dynamical mass. The application of the inhomogeneous model to the {sigma}(Z){sup 2}- Z-bar relationship provides a numerical formalism to connect the self-enrichment and pre-enrichment between star clusters and dwarf galaxies using physically motivated chemical enrichment parameters. Therefore we suggest that the {sigma}(Z){sup 2}- Z-bar relationship can provide insight into what drives the efficiency of star formation and chemical evolution in galaxies, and is an important prediction for galaxy

  11. THE PROPERTIES OF THE STAR-FORMING INTERSTELLAR MEDIUM AT z = 0.8-2.2 FROM HiZELS: STAR FORMATION AND CLUMP SCALING LAWS IN GAS-RICH, TURBULENT DISKS

    SciTech Connect

    Swinbank, A. M.; Smail, Ian; Theuns, T.; Sobral, D.; Best, P. N.; Geach, J. E.

    2012-12-01

    We present adaptive optics assisted integral field spectroscopy of nine H{alpha}-selected galaxies at z = 0.84-2.23 drawn from the HiZELS narrowband survey. Our observations map the kinematics of these star-forming galaxies on {approx}kpc scales. We demonstrate that within the interstellar medium of these galaxies, the velocity dispersion of the star-forming gas ({sigma}) follows a scaling relation {sigma}{proportional_to}{Sigma}{sup 1/n} {sub SFR} + constant (where {Sigma}{sub SFR} is the star formation surface density and the constant includes the stellar surface density). Assuming the disks are marginally stable (Toomre Q = 1), this follows from the Kennicutt-Schmidt relation ({Sigma}{sub SFR} = A{Sigma} {sup n} {sub gas}), and we derive best-fit parameters of n = 1.34 {+-} 0.15 and A = 3.4{sup +2.5} {sub -1.6} Multiplication-Sign 10{sup -4} M {sub Sun} yr{sup -1} kpc{sup -2}, consistent with the local relation, and implying cold molecular gas masses of M {sub gas} = 10{sup 9-10} M {sub Sun} and molecular gas fractions of M {sub gas}/(M {sub gas} + M {sub *}) = 0.3 {+-} 0.1, with a range of 10%-75%. We also identify 11 {approx}kpc-scale star-forming regions (clumps) within our sample and show that their sizes are comparable to the wavelength of the fastest growing mode. The luminosities and velocity dispersions of these clumps follow the same scaling relations as local H II regions, although their star formation densities are a factor {approx}15 {+-} 5 Multiplication-Sign higher than typically found locally. We discuss how the clump properties are related to the disk, and show that their high masses and luminosities are a consequence of the high disk surface density.

  12. The hallucinogen N,N-dimethyltryptamine (DMT) is an endogenous sigma-1 receptor regulator.

    PubMed

    Fontanilla, Dominique; Johannessen, Molly; Hajipour, Abdol R; Cozzi, Nicholas V; Jackson, Meyer B; Ruoho, Arnold E

    2009-02-13

    The sigma-1 receptor is widely distributed in the central nervous system and periphery. Originally mischaracterized as an opioid receptor, the sigma-1 receptor binds a vast number of synthetic compounds but does not bind opioid peptides; it is currently considered an orphan receptor. The sigma-1 receptor pharmacophore includes an alkylamine core, also found in the endogenous compound N,N-dimethyltryptamine (DMT). DMT acts as a hallucinogen, but its receptor target has been unclear. DMT bound to sigma-1 receptors and inhibited voltage-gated sodium ion (Na+) channels in both native cardiac myocytes and heterologous cells that express sigma-1 receptors. DMT induced hypermobility in wild-type mice but not in sigma-1 receptor knockout mice. These biochemical, physiological, and behavioral experiments indicate that DMT is an endogenous agonist for the sigma-1 receptor.

  13. Characterizing the interplay betwen mulitple levels of organization within bacterial sigma factor regulatory networks

    SciTech Connect

    Yu, Qiu; Nagarajan, Harish; Embree, Mallory; Shieu, Wendy; Abate, Elisa; Juarez, Katy; Cho, Byung-Kwan; Elkins, James G; Nevin, Kelly P.; Barrett, Christian; Lovley, Derek; Palsson, Bernhard O.; Zengler, Karsten

    2013-01-01

    Bacteria contain multiple sigma factors, each targeting diverse, but often overlapping sets of promoters, thereby forming a complex network. The layout and deployment of such a sigma factor network directly impacts global transcriptional regulation and ultimately dictates the phenotype. Here we integrate multi-omic data sets to determine the topology, the operational, and functional states of the sigma factor network in Geobacter sulfurreducens, revealing a unique network topology of interacting sigma factors. Analysis of the operational state of the sigma factor network shows a highly modular structure with sN being the major regulator of energy metabolism. Surprisingly, the functional state of the network during the two most divergent growth conditions is nearly static, with sigma factor binding profiles almost invariant to environmental stimuli. This first comprehensive elucidation of the interplay between different levels of the sigma factor network organization is fundamental to characterize transcriptional regulatory mechanisms in bacteria.

  14. Sigma: Strain-level inference of genomes from metagenomic analysis for biosurveillance

    SciTech Connect

    Ahn, Tae-Hyuk; Chai, Juanjuan; Pan, Chongle

    2014-09-29

    Motivation: Metagenomic sequencing of clinical samples provides a promising technique for direct pathogen detection and characterization in biosurveillance. Taxonomic analysis at the strain level can be used to resolve serotypes of a pathogen in biosurveillance. Sigma was developed for strain-level identification and quantification of pathogens using their reference genomes based on metagenomic analysis. Results: Sigma provides not only accurate strain-level inferences, but also three unique capabilities: (i) Sigma quantifies the statistical uncertainty of its inferences, which includes hypothesis testing of identified genomes and confidence interval estimation of their relative abundances; (ii) Sigma enables strain variant calling by assigning metagenomic reads to their most likely reference genomes; and (iii) Sigma supports parallel computing for fast analysis of large datasets. In conclusion, the algorithm performance was evaluated using simulated mock communities and fecal samples with spike-in pathogen strains. Availability and Implementation: Sigma was implemented in C++ with source codes and binaries freely available at http://sigma.omicsbio.org.

  15. Exploring the role of sigma factor gene expression on production by Corynebacterium glutamicum: sigma factor H and FMN as example

    PubMed Central

    Taniguchi, Hironori; Wendisch, Volker F.

    2015-01-01

    Bacteria are known to cope with environmental changes by using alternative sigma factors binding to RNA polymerase core enzyme. Sigma factor is one of the targets to modify transcription regulation in bacteria and to influence production capacities. In this study, the effect of overexpressing each annotated sigma factor gene in Corynebacterium glutamicum WT was assayed using an IPTG inducible plasmid system and different IPTG concentrations. It was revealed that growth was severely decreased when sigD or sigH were overexpressed with IPTG concentrations higher than 50 μM. Overexpression of sigH led to an obvious phenotypic change, a yellow-colored supernatant. High performance liquid chromatography analysis revealed that riboflavin was excreted to the medium when sigH was overexpressed and DNA microarray analysis confirmed increased expression of riboflavin biosynthesis genes. In addition, genes for enzymes related to the pentose phosphate pathway and for enzymes dependent on flavin mononucleotide (FMN), flavin adenine dinucleotide (FAD), or NADPH as cofactor were upregulated when sigH was overexpressed. To test if sigH overexpression can be exploited for production of riboflavin-derived FMN or FAD, the endogenous gene for bifunctional riboflavin kinase/FMN adenyltransferase was co-expressed with sigH from a plasmid. Balanced expression of sigH and ribF improved accumulation of riboflavin (19.8 ± 0.3 μM) and allowed for its conversion to FMN (33.1 ± 1.8 μM) in the supernatant. While a proof-of-concept was reached, conversion was not complete and titers were not high. This study revealed that inducible and gradable overexpression of sigma factor genes is an interesting approach to switch gene expression profiles and to discover untapped potential of bacteria for chemical production. PMID:26257719

  16. STELLAR CORONAE, SOLAR FLARES: A DETAILED COMPARISON OF {sigma} GEM, HR 1099, AND THE SUN IN HIGH-RESOLUTION X-RAYS

    SciTech Connect

    Huenemoerder, David P.; Phillips, Kenneth J. H.; Sylwester, Janusz; Sylwester, Barbara E-mail: kennethjhphillips@yahoo.com E-mail: bs@cbk.pan.wroc.pl

    2013-05-10

    The Chandra High Energy Transmission Grating Spectrometer (HETG) spectra of the coronally active binary stars {sigma} Gem and HR 1099 are among the highest fluence observations for such systems taken at high spectral resolution in X-rays with this instrument. This allows us to compare their properties in detail to solar flare spectra obtained with the Russian CORONAS-F spacecraft's RESIK instrument at similar resolution in an overlapping bandpass. Here we emphasize the detailed comparisons of the 3.3-6.1 A region (including emission from highly ionized S, Si, Ar, and K) from solar flare spectra to the corresponding {sigma} Gem and HR 1099 spectra. We also model the larger wavelength range of the HETG, from 1.7 to 25 A - having emission lines from Fe, Ca, Ar, Si, Al, Mg, Ne, O, and N-to determine coronal temperatures and abundances. {sigma} Gem is a single-lined coronally active long-period binary which has a very hot corona. HR 1099 is a similar, but shorter period, double-lined system. With very deep HETG exposures we can even study emission from some of the weaker species, such as K, Na, and Al, which are important since they have the lowest first ionization potentials, a parameter well known to be correlated with elemental fractionation in the solar corona. The solar flare temperatures reach Almost-Equal-To 20 MK, comparable to the {sigma} Gem and HR 1099 coronae. During the Chandra exposures, {sigma} Gem was slowly decaying from a flare and its spectrum is well characterized by a collisional ionization equilibrium plasma with a broad temperature distribution ranging from 2 to 60 MK, peaking near 25 MK, but with substantial emission from 50 MK plasma. We have detected K XVIII and Na XI emission which allow us to set limits on their abundances. HR 1099 was also quite variable in X-rays, also in a flare state, but had no detectable K XVIII. These measurements provide new comparisons of solar and stellar coronal abundances, especially at the lowest first ionization

  17. Growth phase-regulated expression of bolA and morphology of stationary-phase Escherichia coli cells are controlled by the novel sigma factor sigma S.

    PubMed

    Lange, R; Hengge-Aronis, R

    1991-07-01

    The novel sigma factor (sigma S) encoded by rpoS (katF) is required for induction of many growth phase-regulated genes and expression of a variety of stationary-phase phenotypes in Escherichia coli. Here we demonstrate that wild-type cells exhibit spherical morphology in stationary phase, whereas rpoS mutant cells remain rod shaped and are generally larger. Size reduction of E. coli cells along the growth curve is a continuous and at least biphasic process, the second phase of which is absent in rpoS-deficient cells and correlates with induction of the morphogene bolA in wild-type cells. Stationary-phase induction of bolA is dependent on sigma S. The "gearbox" a characteristic sequence motif present in the sigma S-dependent growth phase- and growth rate-regulated bolAp1 promoter, is not recognized by sigma S, since stationary-phase induction of the mcbA promoter, which also contains a gearbox, does not require sigma S, and other sigma S-controlled promoters do not contain gearboxes. However, good homology to the potential -35 and -10 consensus sequences for sigma S regulation is found in the bolAp1 promoter.

  18. The C-Terminal RpoN Domain of sigma54 Forms an unpredictedHelix-Turn-Helix Motif Similar to domains of sigma70

    SciTech Connect

    Doucleff, Michaeleen; Malak, Lawrence T.; Pelton, Jeffrey G.; Wemmer, David E.

    2005-11-01

    The ''{delta}'' subunit of prokaryotic RNA-polymerase allows gene-specific transcription initiation. Two {sigma} families have been identified, {sigma}{sup 70} and {sigma}{sup 54}, which use distinct mechanisms to initiate transcription and share no detectable sequence homology. Although the {sigma}{sup 70}-type factors have been well characterized structurally by x-ray crystallography, no high-resolution structural information is available for the {sigma}{sup 54}-type factors. Here we present the NMR derived structure of the C-terminal domain of {sigma}{sup 54} from Aquifex aeolicus. This domain (Thr323 to Gly389), which contains the highly conserved RpoN box sequence, consists of a poorly structured N-terminal tail followed by a three-helix bundle, which is surprisingly similar to domains of the {sigma}{sup 70}-type proteins. Residues of the RpoN box, which have previously been shown to be critical for DNA binding, form the second helix of an unpredicted helix-turn-helix motif. This structure's homology with other DNA binding proteins, combined with previous biochemical data, suggest how the C-terminal domain of {sigma}{sup 54} binds to DNA.

  19. SEGUE: A Spectroscopic Survey of 240,000 stars with g=14-20

    SciTech Connect

    Yanny, Brian; Rockosi, Constance; Newberg, Heidi Jo; Knapp, Gillian R.; Adelman-McCarthy, Jennifer K.; Alcorn, Bonnie; Allam, Sahar S.; Prieto, Carlos Allende; An, Deokkeun; Anderson, Kurt S.J.; Anderson, Scott; /Washington U., Seattle

    2009-02-01

    The Sloan Extension for Galactic Understanding and Exploration (SEGUE) Survey obtained {approx}240,000 moderate-resolution (R {approx} 1800) spectra from 3900 {angstrom} to 9000 {angstrom} of fainter Milky Way stars (14.0 < g < 20.3) of a wide variety of spectral types, both main-sequence and evolved objects, with the goal of studying the kinematics and populations of our Galaxy and its halo. The spectra are clustered in 212 regions spaced over three quarters of the sky. Radial velocity accuracies for stars are {sigma}(RV) {approx} 4 km s{sup -1} at g < 18, degrading to {sigma}(RV) {approx} 15 km s{sup -1} at g {approx} 20. For stars with signal-to-noise ratio >10 per resolution element, stellar atmospheric parameters are estimated, including metallicity, surface gravity, and effective temperature. SEGUE obtained 3500 deg{sup 2} of additional ugriz imaging (primarily at low Galactic latitudes) providing precise multicolor photometry ({sigma}(g, r, i) {approx} 2%), ({sigma}(u, z) {approx} 3%) and astrometry ({approx}0.1) for spectroscopic target selection. The stellar spectra, imaging data, and derived parameter catalogs for this survey are publicly available as part of Sloan Digital Sky Survey Data Release 7.

  20. B fields in OB stars (BOB): Detection of a magnetic field in the He-strong star CPD -57° 3509

    NASA Astrophysics Data System (ADS)

    Przybilla, N.; Fossati, L.; Hubrig, S.; Nieva, M.-F.; Järvinen, S. P.; Castro, N.; Schöller, M.; Ilyin, I.; Butler, K.; Schneider, F. R. N.; Oskinova, L. M.; Morel, T.; Langer, N.; de Koter, A.; BOB Collaboration

    2016-03-01

    Aims: We report the detection of a magnetic field in the helium-strong star CPD -57° 3509 (B2 IV), a member of the Galactic open cluster NGC 3293, and characterise the star's atmospheric and fundamental parameters. Methods: Spectropolarimetric observations with FORS2 and HARPSpol are analysed using two independent approaches to quantify the magnetic field strength. A high-S/N FLAMES/GIRAFFE spectrum is analysed using a hybrid non-LTE model atmosphere technique. Comparison with stellar evolution models constrains the fundamental parameters of the star. Results: We obtain a firm detection of a surface averaged longitudinal magnetic field with a maximum amplitude of about 1 kG. Assuming a dipolar configuration of the magnetic field, this implies a dipolar field strength larger than 3.3 kG. Moreover, the large amplitude and fast variation (within about 1 day) of the longitudinal magnetic field implies that CPD -57° 3509 is spinning very fast despite its apparently slow projected rotational velocity. The star should be able to support a centrifugal magnetosphere, yet the spectrum shows no sign of magnetically confined material; in particular, emission in Hα is not observed. Apparently, the wind is either not strong enough for enough material to accumulate in the magnetosphere to become observable or, alternatively, some leakage process leads to loss of material from the magnetosphere. The quantitative spectroscopic analysis of the star yields an effective temperature and a logarithmic surface gravity of 23 750 ± 250 K and 4.05 ± 0.10, respectively, and a surface helium fraction of 0.28 ± 0.02 by number. The surface abundances of C, N, O, Ne, S, and Ar are compatible with the cosmic abundance standard, whereas Mg, Al, Si, and Fe are depleted by about a factor of 2. This abundance pattern can be understood as the consequence of a fractionated stellar wind. CPD -57° 3509 is one of the most evolved He-strong stars known with an independent age constraint due to its

  1. Using Six Sigma to improve the film library.

    PubMed

    Benedetto, Anthony R; Dunnington, Joel S; Oxford-Zelenske, Deborah

    2002-01-01

    The film library of a film-based radiology department is a mission-critical component of the department that is frequently underappreciated and under-staffed. A poorly performing film library causes operational problems for not only the radiology department, but for the institution as a whole. Since Six Sigma techniques had proved successful in an earlier CT throughput improvement project, the University of Texas M.D. Anderson Cancer Center Division of Diagnostic Imaging decided to use Six Sigma techniques to dramatically improve the performance of its film library. Nine mini-project teams were formed to address the basic operating functions of the film library. The teams included film library employees, employees from other sections of radiology, employees from stakeholders outside of radiology, and radiologists and referring physicians, as appropriate to the team's mission. Each Six Sigma team developed a process map of the current process, reviewed or acquired baseline quantitative data to assess the current level of performance, and then modified the process map to incorporate their recommendations for improving the process. An overall project steering committee reviewed recommendations from each Six Sigma team to assure that all of the teams' efforts were coordinated and aligned with the overall project goals. The steering committee also provided advice on implementation strategies, particularly for changes that would have an immediate effect on stakeholders outside of the radiology department. After implementation of recommendations, quantitative data were collected again to determine if the changes were having the desired effect. Improvement in both quantitative metrics and in employee morale have been experienced. We continue to collect data as assurance that the improvements are being sustained over the long haul. Six Sigma techniques, which are as quantitatively-based as possible, are useful in a service-oriented organization, such as a film library. The

  2. Stabilization of the primary sigma factor of Staphylococcus aureus by core RNA polymerase.

    PubMed

    Mondal, Rajkrishna; Ganguly, Tridib; Chanda, Palas K; Bandhu, Amitava; Jana, Biswanath; Sau, Keya; Lee, Chia Y; Sau, Subrata

    2010-03-01

    The primary sigma factor (sigma(A)) of Staphylococcus aureus, a potential drug target, was little investigated at the structural level. Using an N-terminal histidine-tagged sigma(A) (His-sigma(A)), here we have demonstrated that it exits as a monomer in solution, possesses multiple domains, harbors primarily alpha-helix and efficiently binds to a S. aureus promoter DNA in the presence of core RNA polymerase. While both N- and C-terminal ends of His- sigma(A) are flexible in nature, two Trp residues in its DNA binding region are buried. Upon increasing the incubation temperature from 25 degrees to 40 degrees C, 60% of the input His-sigma(A) was cleaved by thermolysin. Aggregation of His-sigma(A) was also initiated rapidly at 45( degrees )C. From the equilibrium unfolding experiment, the Gibbs free energy of stabilization of His-sigma(A) was estimated to be +0.70 kcal mol(-1). The data together suggest that primary sigma factor of S. aureus is an unstable protein. Core RNA polymerase however stabilized sigma(A) appreciably.

  3. Synchrotron Based Observations of Sigma Phase Formation and Dissolution in Duplex Stainless Steel

    SciTech Connect

    Elmer, J; Palmer, T; Specht, E

    2006-08-22

    The formation and growth of sigma ({sigma}) phase in 2205 duplex stainless steel was observed and measured in real time using synchrotron radiation during isothermal heat treating at temperatures between 700 C and 850 C. Synchrotron experiments were performed on this material at the Advanced Photon Source (APS) while isothermally holding the samples for times of up to 10 hr. During the isothermal hold, sigma formed in quantities up to 22% as the ferrite transformed to a mixture of sigma and austenite phases. In addition, sigma formed at 850 C was heated to 1000 C to observe its dissolution. The amounts of sigma that formed, and the dissolution temperature of sigma were compared to the results predicted by Thermocalc, showing differences between the calculated and measured values. The synchrotron data was further modeled using a modified Johnson-Mehl-Avrami analysis to determine kinetic parameters for sigma formation. The initial JMA exponent, n, at low fractions of sigma was found to be approximately 7.0, however, towards the end of the transformation, n decreased to values of approximately 0.75. Because of the variable value of n, it was not possible to determine reliable values for the activation energy and pre-exponential terms for the JMA equation. During cooling to room temperature, the high temperature austenite partially transformed to ferrite, substantially increasing the ferrite content while the sigma phase kept its high temperature value.

  4. Allosteric modulation of ligand binding to [3H](+)pentazocine-defined sigma recognition sites by phenytoin.

    PubMed

    DeHaven-Hudkins, D L; Ford-Rice, F Y; Allen, J T; Hudkins, R L

    1993-01-01

    The allosteric modulation of sigma recognition sites by phenytoin (diphenylhydantoin) has been demonstrated by the ability of phenytoin to stimulate binding of various [3H] sigma ligands, as well as to slow dissociation from sigma sites and to shift sigma sites from a low- to a high-affinity state. Phenytoin stimulated the binding of the sigma 1- selective ligand [3H](+)pentazocine in a dose-dependent manner. Stimulation of binding at a final concentration of 250 microM phenytoin was associated with a decrease in the KD. The affinities of the sigma reference compounds caramiphen, dextromethorphan, dextrophan, (+)3-PPP and (+)SKF-10,047 were three- to eight-fold higher, while the affinities of benzetimide, BMY-14802, carbetapentane, DTG and haloperidol were unchanged in the presence of 250 microM phenytoin. The relative sensitivity of sigma compounds to allosteric modulation by phenytoin is not a property of all sigma ligands, and may provide an in vitro basis for distinguishing actions of sigma compounds and predicting sigma effects in vivo. PMID:8515681

  5. Synchrotron Based Observations of Sigma Phase Formation and Dissolution in Duplex Stainless Steel

    SciTech Connect

    Elmer, J. W.; Palmer, T. A.; Specht, Eliot D

    2007-01-01

    The formation and growth of sigma ({sigma}) phase in 2205 duplex stainless steel was observed and measured in real time using synchrotron radiation during isothermal heat treating at temperatures between 700 C and 850 C. Synchrotron experiments were performed on this material at the Advanced Photon Source (APS) while isothermally holding the samples for times of up to 10 hr. During the isothermal hold, sigma formed in quantities up to 22% as the ferrite transformed to a mixture of sigma and austenite phases. In addition, sigma formed at 850 C was heated to 1000 C to observe its dissolution. The amounts of sigma that formed, and the dissolution temperature of sigma were compared to the results predicted by Thermocalc, showing differences between the calculated and measured values. The synchrotron data was further modeled using a modified Johnson-Mehl-Avrami analysis to determine kinetic parameters for sigma formation. The initial JMA exponent, n, at low fractions of sigma was found to be approximately 7.0, however, towards the end of the transformation, n decreased to values of approximately 0.75. Because of the variable value of n, it was not possible to determine reliable values for the activation energy and pre-exponential terms for the JMA equation. During cooling to room temperature, the high temperature austenite partially transformed to ferrite, substantially increasing the ferrite content while the sigma phase kept its high temperature value.

  6. Characterization of 4-Nitrophenylpropyl-N-alkylamine Interactions with Sigma Receptors

    PubMed Central

    Chu, Uyen B.; Hajipour, Abdol R.; Ramachandran, Subramaniam; Ruoho, Arnold E.

    2011-01-01

    Sigma receptors are small membrane proteins implicated in a number of pathophysiological conditions including drug addiction, psychosis and cancer; thus, small molecule inhibitors of sigma receptors have been proposed as potential pharmacotherapeutics for these diseases. We previously discovered that endogenous monochain N-alkyl sphingolipids including D-erythro-sphingosine, sphinganine, and N,N-dimethyl sphingosine bind to the sigma-1 receptor at physiologically relevant concentrations [Ramachandran et al. 2009 Eur J Pharmacol. 609(1–3):19–26]. Here, we investigated several N-alkylamines of varying chain lengths as sigma receptor ligands. Although the KI values for N-alkylamines were found to be in the micromolar range, when N-3-phenylpropyl and N-3-(4-nitrophenyl)propyl derivatives of butyl- (1a and 1b), heptyl- (2a and 2b), dodecyl- (3a and 3b), and octadecyl-amine (4a and 4b) were evaluated as sigma receptor ligands we found that these compounds exhibited nanomolar affinities with both sigma-1 and sigma-2 receptors. A screen of the high affinity ligands 2a, 2b, 3a and 3b against a variety of other receptors/transporters confirmed these four compounds to be highly selective mixed sigma-1 and sigma-2 ligands. Additionally, in HEK293 cells reconstituted with Kv1.4 potassium channel and the sigma-1 receptor, these derivatives were able to inhibit the outward current from the channel – consistent with sigma receptor modulation. Finally, cytotoxicity assays showed that 2a, 2b, 3a and 3b were highly potent against a number of cancer cell lines, demonstrating their potential utility as mixed sigma-1 and sigma-2 receptor anti-cancer agents. PMID:21790129

  7. O stars and Wolf-Rayet stars

    NASA Technical Reports Server (NTRS)

    Conti, Peter S.; Underhill, Anne B.; Jordan, Stuart (Editor); Thomas, Richard (Editor)

    1988-01-01

    Basic information is given about O and Wolf-Rayet stars indicating how these stars are defined and what their chief observable properties are. Part 2 of the volume discussed four related themes pertaining to the hottest and most luminous stars. Presented are: an observational overview of the spectroscopic classification and extrinsic properties of O and Wolf-Rayet stars; the intrinsic parameters of luminosity, effective temperature, mass, and composition of the stars, and a discussion of their viability; stellar wind properties; and the related issues concerning the efforts of stellar radiation and wind on the immediate interstellar environment are presented.

  8. EXOZODIACAL DUST LEVELS FOR NEARBY MAIN-SEQUENCE STARS: A SURVEY WITH THE KECK INTERFEROMETER NULLER

    SciTech Connect

    Millan-Gabet, R.; Serabyn, E.; Mennesson, B.; Traub, W. A.; Stapelfeldt, K.; Bryden, G.; Colavita, M. M.; Booth, A. J.; Barry, R. K.; Danchi, W. C.; Kuchner, M.; Stark, C. C.; Ragland, S.; Hrynevych, M.; Woillez, J.

    2011-06-10

    The Keck Interferometer Nuller (KIN) was used to survey 25 nearby main-sequence stars in the mid-infrared, in order to assess the prevalence of warm circumstellar (exozodiacal) dust around nearby solar-type stars. The KIN measures circumstellar emission by spatially blocking the star but transmitting the circumstellar flux in a region typically 0.1-4 AU from the star. We find one significant detection ({eta} Crv), two marginal detections ({gamma} Oph and {alpha} Aql), and 22 clear non-detections. Using a model of our own solar system's zodiacal cloud, scaled to the luminosity of each target star, we estimate the equivalent number of target zodis needed to match our observations. Our three zodi detections are {eta} Crv (1250 {+-} 260), {gamma} Oph (200 {+-} 80), and {alpha} Aql (600 {+-} 200), where the uncertainties are 1{sigma}. The 22 non-detected targets have an ensemble weighted average consistent with zero, with an average individual uncertainty of 160 zodis (1{sigma}). These measurements represent the best limits to date on exozodi levels for a sample of nearby main-sequence stars. A statistical analysis of the population of 23 stars not previously known to contain circumstellar dust (excluding {eta} Crv and {gamma} Oph) suggests that, if the measurement errors are uncorrelated (for which we provide evidence) and if these 23 stars are representative of a single class with respect to the level of exozodi brightness, the mean exozodi level for the class is <150 zodis (3{sigma} upper limit, corresponding to 99% confidence under the additional assumption that the measurement errors are Gaussian). We also demonstrate that this conclusion is largely independent of the shape and mean level of the (unknown) true underlying exozodi distribution.

  9. A review of sigma models for quantum chaotic dynamics.

    PubMed

    Altland, Alexander; Gnutzmann, Sven; Haake, Fritz; Micklitz, Tobias

    2015-07-01

    We review the construction of the supersymmetric sigma model for unitary maps, using the color-flavor transformation. We then illustrate applications by three case studies in quantum chaos. In two of these cases, general Floquet maps and quantum graphs, we show that universal spectral fluctuations arise provided the pertinent classical dynamics are fully chaotic (ergodic and with decay rates sufficiently gapped away from zero). In the third case, the kicked rotor, we show how the existence of arbitrarily long-lived modes of excitation (diffusion) precludes universal fluctuations and entails quantum localization. PMID:26181515

  10. Effect of ring-constrained phenylpropyloxyethylamines on sigma receptors.

    PubMed

    Stavitskaya, Lidiya; Seminerio, Michael J; Healy, Jason R; Noorbakhsh, Bahar; Matsumoto, Rae R; Coop, Andrew

    2013-09-01

    A series of ring-constrained phenylpropyloxyethylamines, partial opioid structure analogs and derivatives of a previously studied sigma (σ) receptor ligand, was synthesized and evaluated at σ and opioid receptors for receptor selectivity. The results of this study identified several compounds with nanomolar affinity at both σ receptor subtypes. Compounds 6 and 9 had the highest selectivity for both σ receptor subtypes, compared to μ opioid receptors. In addition, compounds 6 and 9 significantly reduced the convulsive effects of cocaine in mice, which would be consistent with antagonism of σ receptors. PMID:23896610

  11. A review of sigma models for quantum chaotic dynamics.

    PubMed

    Altland, Alexander; Gnutzmann, Sven; Haake, Fritz; Micklitz, Tobias

    2015-07-01

    We review the construction of the supersymmetric sigma model for unitary maps, using the color-flavor transformation. We then illustrate applications by three case studies in quantum chaos. In two of these cases, general Floquet maps and quantum graphs, we show that universal spectral fluctuations arise provided the pertinent classical dynamics are fully chaotic (ergodic and with decay rates sufficiently gapped away from zero). In the third case, the kicked rotor, we show how the existence of arbitrarily long-lived modes of excitation (diffusion) precludes universal fluctuations and entails quantum localization.

  12. Universal spectral correlations from the ballistic sigma model.

    PubMed

    Müller, Jan; Micklitz, Tobias; Altland, Alexander

    2007-11-01

    We consider the semiclassical ballistic sigma model as an effective theory describing the quantum mechanics of classically chaotic systems. Specifically, we elaborate on close analogies to the recently developed semiclassical theory of quantum interference in chaotic systems and show how semiclassical "diagrams" involving near action degenerate sets of periodic orbits emerge in the field theoretical description. We further discuss how the universality phenomenon (i.e., the fact that individual chaotic systems behave according to the prescriptions of random matrix theory) can be understood from the perspective of the field theory.

  13. Six Sigma in health care management and strategy.

    PubMed

    Carrigan, Martin D; Kujawa, David

    2006-01-01

    In the years ahead, health care organizations will continue to face numerous challenges from longstanding and currently unresolved issues and new and emerging trends. Some of these include workforce shortages, rising consumerism, patient and stakeholder expectations, quality and patient safety, reimbursement, an aging population, regulatory constraints, and disaster preparedness. Health care organizations will need to adopt effective strategic tools, such as Six Sigma, to improve efficiency and effectiveness. Failure to do so will not only threaten their ability to remain competitive and provide quality care to the communities they serve, but their own survival will also be jeopardized by shrinking margins caused by continued downward pressure on reimbursement.

  14. On symmetries of = (4, 4) sigma models on T 4

    NASA Astrophysics Data System (ADS)

    Volpato, Roberto

    2014-08-01

    Motivated by an analogous result for K3 models, we classify all groups of symmetries of non-linear sigma models on a torus T 4 that preserve the = (4 , 4) superconformal algebra. The resulting symmetry groups are isomorphic to certain subgroups of the Weyl group of E 8, that plays a role similar to the Conway group for the case of K3 models. Our analysis heavily relies on the triality automorphism of the T-duality group SO(4 , 4 , ℤ). As a byproduct of our results, we discover new explicit descriptions of K3 models as asymmetric orbifolds of torus CFTs.

  15. A review of sigma models for quantum chaotic dynamics

    NASA Astrophysics Data System (ADS)

    Altland, Alexander; Gnutzmann, Sven; Haake, Fritz; Micklitz, Tobias

    2015-07-01

    We review the construction of the supersymmetric sigma model for unitary maps, using the color-flavor transformation. We then illustrate applications by three case studies in quantum chaos. In two of these cases, general Floquet maps and quantum graphs, we show that universal spectral fluctuations arise provided the pertinent classical dynamics are fully chaotic (ergodic and with decay rates sufficiently gapped away from zero). In the third case, the kicked rotor, we show how the existence of arbitrarily long-lived modes of excitation (diffusion) precludes universal fluctuations and entails quantum localization.

  16. Lifestyles of the Stars.

    ERIC Educational Resources Information Center

    National Aeronautics and Space Administration, Cocoa Beach, FL. John F. Kennedy Space Center.

    Some general information on stars is provided in this National Aeronautics and Space Administration pamphlet. Topic areas briefly discussed are: (1) the birth of a star; (2) main sequence stars; (3) red giants; (4) white dwarfs; (5) neutron stars; (6) supernovae; (7) pulsars; and (8) black holes. (JN)

  17. Egyptian "Star Clocks"

    NASA Astrophysics Data System (ADS)

    Symons, Sarah

    Diagonal, transit, and Ramesside star clocks are tables of astronomical information occasionally found in ancient Egyptian temples, tombs, and papyri. The tables represent the motions of selected stars (decans and hour stars) throughout the Egyptian civil year. Analysis of star clocks leads to greater understanding of ancient Egyptian constellations, ritual astronomical activities, observational practices, and pharaonic chronology.

  18. DISENTANGLING AGN AND STAR FORMATION IN SOFT X-RAYS

    SciTech Connect

    LaMassa, Stephanie M.; Heckman, T. M.; Ptak, A.

    2012-10-20

    We have explored the interplay of star formation and active galactic nucleus (AGN) activity in soft X-rays (0.5-2 keV) in two samples of Seyfert 2 galaxies (Sy2s). Using a combination of low-resolution CCD spectra from Chandra and XMM-Newton, we modeled the soft emission of 34 Sy2s using power-law and thermal models. For the 11 sources with high signal-to-noise Chandra imaging of the diffuse host galaxy emission, we estimate the luminosity due to star formation by removing the AGN, fitting the residual emission. The AGN and star formation contributions to the soft X-ray luminosity (i.e., L{sub x,AGN} and L{sub x,SF}) for the remaining 24 Sy2s were estimated from the power-law and thermal luminosities derived from spectral fitting. These luminosities were scaled based on a template derived from XSINGS analysis of normal star-forming galaxies. To account for errors in the luminosities derived from spectral fitting and the spread in the scaling factor, we estimated L{sub x,AGN} and L{sub x,SF} from Monte Carlo simulations. These simulated luminosities agree with L{sub x,AGN} and L{sub x,SF} derived from Chandra imaging analysis within a 3{sigma} confidence level. Using the infrared [Ne II]12.8 {mu}m and [O IV]26 {mu}m lines as a proxy of star formation and AGN activity, respectively, we independently disentangle the contributions of these two processes to the total soft X-ray emission. This decomposition generally agrees with L{sub x,SF} and L{sub x,AGN} at the 3{sigma} level. In the absence of resolvable nuclear emission, our decomposition method provides a reasonable estimate of emission due to star formation in galaxies hosting type 2 AGNs.

  19. AN ULTRAVIOLET INVESTIGATION OF ACTIVITY ON EXOPLANET HOST STARS

    SciTech Connect

    Shkolnik, Evgenya L.

    2013-03-20

    Using the far-UV (FUV) and near-UV (NUV) photometry from the NASA Galaxy Evolution Explorer (GALEX), we searched for evidence of increased stellar activity due to tidal and/or magnetic star-planet interactions (SPI) in the 272 known FGK planetary hosts observed by GALEX. With the increased sensitivity of GALEX, we are able probe systems with lower activity levels and at larger distances than what has been done to date with X-ray satellites. We compared samples of stars with close-in planets (a < 0.1 AU) to those with far-out planets (a > 0.5 AU) and looked for correlations of excess activity with other system parameters. This statistical investigation found no clear correlations with a, M{sub p} , or M{sub p} /a, in contrast to some X-ray and Ca II studies. However, there is tentative evidence (at a level of 1.8{sigma}) that stars with radial-velocity-(RV)-detected close-in planets are more FUV-active than stars with far-out planets, in agreement with several published X-ray and Ca II results. The case is strengthened to a level of significance to 2.3{sigma} when transit-detected close-in planets are included. This is most likely because the RV-selected sample of stars is significantly less active than the field population of comparable stars, while the transit-selected sample is similarly active. Given the factor of 2-3 scatter in fractional FUV luminosity for a given stellar effective temperature, it is necessary to conduct a time-resolved study of the planet hosts in order to better characterize their UV variability and generate a firmer statistical result.

  20. NEW DEBRIS DISK CANDIDATES AROUND 49 NEARBY STARS

    SciTech Connect

    Koerner, D. W.; Kim, S.; Trilling, D. E.; Larson, H.; Cotera, A.; Stapelfeldt, K. R.; Wahhaj, Z.; Fajardo-Acosta, S.; Padgett, D.; Backman, D.

    2010-02-10

    We present 49 new candidate debris disks that were detected around nearby stars with the Spitzer Space Telescope using the Multiband Imaging Photometer (MIPS) at 24 {mu}m (MIPS24) and 70 {mu}m (MIPS70). The survey sample was composed of stars within 25 pc of the Sun that were not previously observed by any other MIPS survey. Only stars with V < 9 were selected, corresponding to spectral types earlier than M0. MIPS24 integration times were chosen to detect the stellar photosphere at 10{sigma} levels or better. MIPS70 observations were designed to detect excess infrared emission from any star in the MIPS70 sample with a disk as luminous at that around {epsilon} Eridani. The resulting sample included over 436 nearby stars that were observed with both MIPS24 and MIPS70, plus an additional 198 observed only with MIPS24. Debris disk candidates were defined as targets where excess emission was detected at 3{sigma} levels or greater, and the ratio of observed flux density to expected photosphere emission was three standard deviations or more above the mean value for the sample. The detection rate implied by the resulting 29 MIPS24 candidates is 4.6%. A detection rate of 4.8% is implied by 21 MIPS70 candidates. The distribution of spectral types for stars identified as candidates resembles that of the general sample and yields strong evidence that debris-disk occurrence does not decrease for K dwarfs. Modeling of non-uniform sensitivity in the sample is required to interpret quantitative estimates of the overall detection frequency and will be presented in a future work.

  1. Disentangling AGN and Star Formation in Soft X-Rays

    NASA Technical Reports Server (NTRS)

    LaMassa, Stephanie M.; Heckman, T. M.; Ptak, A.

    2012-01-01

    We have explored the interplay of star formation and active galactic nucleus (AGN) activity in soft X-rays (0.5-2 keV) in two samples of Seyfert 2 galaxies (Sy2s). Using a combination of low-resolution CCD spectra from Chandra and XMM-Newton, we modeled the soft emission of 34 Sy2s using power-law and thermal models. For the 11 sources with high signal-to-noise Chandra imaging of the diffuse host galaxy emission, we estimate the luminosity due to star formation by removing the AGN, fitting the residual emission. The AGN and star formation contributions to the soft X-ray luminosity (i.e., L(sub x,AGN) and L(sub x,SF)) for the remaining 24 Sy2s were estimated from the power-law and thermal luminosities derived from spectral fitting. These luminosities were scaled based on a template derived from XSINGS analysis of normal star-forming galaxies. To account for errors in the luminosities derived from spectral fitting and the spread in the scaling factor, we estimated L(sub x,AGN) and L(sub x,SF))from Monte Carlo simulations. These simulated luminosities agree with L(sub x,AGN) and L(sub x,SF) derived from Chandra imaging analysis within a 3sigma confidence level. Using the infrared [Ne ii]12.8 micron and [O iv]26 micron lines as a proxy of star formation and AGN activity, respectively, we independently disentangle the contributions of these two processes to the total soft X-ray emission. This decomposition generally agrees with L(sub x,SF) and L(sub x,AGN) at the 3 sigma level. In the absence of resolvable nuclear emission, our decomposition method provides a reasonable estimate of emission due to star formation in galaxies hosting type 2 AGNs.

  2. Study of the formation and effects of sigma phase in 21-6-9 stainless steel

    SciTech Connect

    Packard, C.L.; Mataya, M.C.; Edstrom, C.M.

    1981-11-07

    Work performed to date on the study of the formation and effects of sigma phase in 21-6-9 stainless steel is summarized in this report. Sigma phase was identified in forgings and as-rolled plate by color etching and microprobe analysis. In as-rolled plate sigma was found to start transforming from delta ferrite within 30 minutes at 1500/sup 0/F, with almost complete transformation after 24 hours at 1500/sup 0/F. The effect of sigma phase on room temperature mechanical properties was evaluated by tensile testing, Charpy impact testing, and impact shear testing. Sigma phase was found to severely reduce transverse ductility and longtudinal and transverse impact resistance. The greater the amount of sigma present, the greater was its effect on mechanical properties. Vendor contacts indicated that controlling delta ferrite to a minimum in the as-rolled plate is both possible and practical.

  3. The sigma receptor as a ligand-regulated auxiliary potassium channel subunit.

    PubMed

    Aydar, Ebru; Palmer, Christopher P; Klyachko, Vitaly A; Jackson, Meyer B

    2002-04-25

    The sigma receptor is a novel protein that mediates the modulation of ion channels by psychotropic drugs through a unique transduction mechanism depending neither on G proteins nor protein phosphorylation. The present study investigated sigma receptor signal transduction by reconstituting responses in Xenopus oocytes. Sigma receptors modulated voltage-gated K+ channels (Kv1.4 or Kv1.5) in different ways in the presence and absence of ligands. Association between Kv1.4 channels and sigma receptors was demonstrated by coimmunoprecipitation. These results indicate a novel mechanism of signal transduction dependent on protein-protein interactions. Domain accessibility experiments suggested a structure for the sigma receptor with two cytoplasmic termini and two membrane-spanning segments. The ligand-independent effects on channels suggest that sigma receptors serve as auxiliary subunits to voltage-gated K+ channels with distinct functional interactions, depending on the presence or absence of ligand.

  4. Accurate estimation of sigma(exp 0) using AIRSAR data

    NASA Technical Reports Server (NTRS)

    Holecz, Francesco; Rignot, Eric

    1995-01-01

    During recent years signature analysis, classification, and modeling of Synthetic Aperture Radar (SAR) data as well as estimation of geophysical parameters from SAR data have received a great deal of interest. An important requirement for the quantitative use of SAR data is the accurate estimation of the backscattering coefficient sigma(exp 0). In terrain with relief variations radar signals are distorted due to the projection of the scene topography into the slant range-Doppler plane. The effect of these variations is to change the physical size of the scattering area, leading to errors in the radar backscatter values and incidence angle. For this reason the local incidence angle, derived from sensor position and Digital Elevation Model (DEM) data must always be considered. Especially in the airborne case, the antenna gain pattern can be an additional source of radiometric error, because the radar look angle is not known precisely as a result of the the aircraft motions and the local surface topography. Consequently, radiometric distortions due to the antenna gain pattern must also be corrected for each resolution cell, by taking into account aircraft displacements (position and attitude) and position of the backscatter element, defined by the DEM data. In this paper, a method to derive an accurate estimation of the backscattering coefficient using NASA/JPL AIRSAR data is presented. The results are evaluated in terms of geometric accuracy, radiometric variations of sigma(exp 0), and precision of the estimated forest biomass.

  5. Solution to the Sigma Problem of Pulsar Wind Nebulae

    NASA Astrophysics Data System (ADS)

    Porth, Oliver; Komissarov, Serguei S.; Keppens, Rony

    2014-03-01

    Pulsar wind nebulae (PWN) provide a unique test-bed for the study of highly relativistic processes right at our astronomical doorstep. In this contribution we will show results from the first 3D RMHD simulations of PWN. Of key interest to our study is the long standing "sigma-problem" that challenges MHD models of Pulsars and their nebulae now for 3 decades. Earlier 2D MHD models were very successful in reproducing the morphology of the inner Crab nebula showing a jet, torus, concentric wisps and a variable knot. However, these models are limited to a purely toroidal field geometry which leads to an exaggerated compression of the termination shock and polar jet — in contrast to the observations. In three dimensions, the toroidal field structure is susceptible to current driven instabilities; hence kink instability and magnetic dissipation govern the dynamics of the nebula flow. This leads to a resolution of the sigma-problem once also the pulsar's obliqueness (striped wind) is taken into account. In addition, we present polarized synchrotron maps constructed from the 3D simulations, showing the wealth of morphological features reproduced in 2D is preserved in the 3D case.

  6. Non-linear sigma-models and string theories

    SciTech Connect

    Sen, A.

    1986-10-01

    The connection between sigma-models and string theories is discussed, as well as how the sigma-models can be used as tools to prove various results in string theories. Closed bosonic string theory in the light cone gauge is very briefly introduced. Then, closed bosonic string theory in the presence of massless background fields is discussed. The light cone gauge is used, and it is shown that in order to obtain a Lorentz invariant theory, the string theory in the presence of background fields must be described by a two-dimensional conformally invariant theory. The resulting constraints on the background fields are found to be the equations of motion of the string theory. The analysis is extended to the case of the heterotic string theory and the superstring theory in the presence of the massless background fields. It is then shown how to use these results to obtain nontrivial solutions to the string field equations. Another application of these results is shown, namely to prove that the effective cosmological constant after compactification vanishes as a consequence of the classical equations of motion of the string theory. 34 refs. (LEW)

  7. [Colo-uterine fistula, a complication of sigma diverticulitis].

    PubMed

    Nistri, R; Basili, G; Vitali, A; Carrieri, P; Nardi, S

    1998-10-01

    The colo-uterine fistula is a rare complication of diverticular disease of the colon; the literature review has shown only few well studied cases. The fistula, among the complications of the sigma diverticulitis, is 20% of the observed cases; generally, the bladder is the most involved organ, but also the skin or gut can be interested. If we consider the aetiology of the colo=uterine fistula of the observed case, the presence of the sigma locked stenosis with an endocolic pressure increase, associated with a peridiverticulitis condition, seems to have a relevant rule. The clinical symptomatology is represented by vague abdominal pain localized in particular in the left iliac cavity and by emission of blood, purulent material and stools from the vagina. The diagnosis of colo-uterine fistula is not easily reached: barium enema, Fallopian tube endoscopy and colon endoscopy not always allow to visualize in a right manner the fistula and only the oral administration of non-absorbable substances to be searched in the vaginal tampon, clear each doubt. Regarding the therapy to be carried out, we think that, colic resection en bloc with the uterus is the treatment of choice, while, in emergency, the Hartman operation is the most suitable to avoid the beginning of septic complications.

  8. Binding of kappa- and sigma-opiates in rat brain

    SciTech Connect

    Wolozin, B.L.; Nishimura, S.; Pasternak, G.W.

    1982-06-01

    Detailed displacements of (/sup 3/H)dihydromorphine by ketocyclazocine and SKF 10,047, (/sup 3/H)ethylketocyclazocine by SKF 10,047, and (/sup 3/H)SKF 10,047 by ketocyclazocine are all multiphasic, suggesting multiple binding sites. After treating brain tissue in vitro with naloxazone, all displacements lose the initial inhibition of /sup 3/H-ligand binding by low concentrations of unlabeled drugs. Together with Scatchard analysis of saturation experiments, these studies suggest a common site which binds mu-, kappa, and sigma-opiates and enkephalins equally well and with highest affinity (KD less than 1 nM). The ability of unlabeled drugs to displace the low affinity binding of (/sup 3/H)dihydromorphine (KD . 3 nM), (/sup 3/H)ethylketocyclazocine (KD . 4 nM), (/sup 3/H)SKF 10,047 (KD . 6 nM), and D-Ala2-D-Leu5-(/sup 3/H)enkephalin (KD . 5 nM) remaining after treating tissue with naloxazone demonstrates unique pharmacological profiles for each. These results suggest the existence of distinct binding sites for kappa- and sigma-opiates which differ from those sites which selectively bind morphine (mu) and enkephalin (delta).

  9. Improving Quality of Seal Leak Test Product using Six Sigma

    NASA Astrophysics Data System (ADS)

    Luthfi Malik, Abdullah; Akbar, Muhammad; Irianto, Dradjad

    2016-02-01

    Seal leak test part is a polyurethane material-based product. Based on past data, defect level of this product was 8%, higher than the target of 5%. Quality improvement effort was done using six sigma method that included phases of define, measure, analyse, improve, and control. In the design phase, a Delphi method was used to identify factors that were critical to quality. In the measure phase, stability and process capability was measured. Fault tree analysis (FTA) and failure mode and effect analysis (FMEA) were used in the next phase to analize the root cause and to determine the priority issues. Improve phase was done by compiling, selecting, and designing alternative repair. Some improvement efforts were identified, i.e. (i) making a checklist for maintenance schedules, (ii) making written reminder form, (iii) modifying the SOP more detail, and (iv) performing a major service to the vacuum machine. To ensure the continuity of improvement efforts, some control activities were executed, i.e. (i) controlling, monitoring, documenting, and setting target frequently, (ii) implementing reward and punishment system, (iii) adding cleaning tool, and (iv) building six sigma organizational structure.

  10. Six Sigma methods applied to cryogenic coolers assembly line

    NASA Astrophysics Data System (ADS)

    Ventre, Jean-Marc; Germain-Lacour, Michel; Martin, Jean-Yves; Cauquil, Jean-Marc; Benschop, Tonny; Griot, René

    2009-05-01

    Six Sigma method have been applied to manufacturing process of a rotary Stirling cooler: RM2. Name of the project is NoVa as main goal of the Six Sigma approach is to reduce variability (No Variability). Project has been based on the DMAIC guideline following five stages: Define, Measure, Analyse, Improve, Control. Objective has been set on the rate of coolers succeeding performance at first attempt with a goal value of 95%. A team has been gathered involving people and skills acting on the RM2 manufacturing line. Measurement System Analysis (MSA) has been applied to test bench and results after R&R gage show that measurement is one of the root cause for variability in RM2 process. Two more root causes have been identified by the team after process mapping analysis: regenerator filling factor and cleaning procedure. Causes for measurement variability have been identified and eradicated as shown by new results from R&R gage. Experimental results show that regenerator filling factor impacts process variability and affects yield. Improved process haven been set after new calibration process for test bench, new filling procedure for regenerator and an additional cleaning stage have been implemented. The objective for 95% coolers succeeding performance test at first attempt has been reached and kept for a significant period. RM2 manufacturing process is now managed according to Statistical Process Control based on control charts. Improvement in process capability have enabled introduction of sample testing procedure before delivery.

  11. Nonlinear sigma models with compact hyperbolic target spaces

    DOE PAGESBeta

    Gubser, Steven; Saleem, Zain H.; Schoenholz, Samuel S.; Stoica, Bogdan; Stokes, James

    2016-06-23

    We explore the phase structure of nonlinear sigma models with target spaces corresponding to compact quotients of hyperbolic space, focusing on the case of a hyperbolic genus-2 Riemann surface. The continuum theory of these models can be approximated by a lattice spin system which we simulate using Monte Carlo methods. The target space possesses interesting geometric and topological properties which are reflected in novel features of the sigma model. In particular, we observe a topological phase transition at a critical temperature, above which vortices proliferate, reminiscent of the Kosterlitz-Thouless phase transition in the O(2) model [1, 2]. Unlike in themore » O(2) case, there are many different types of vortices, suggesting a possible analogy to the Hagedorn treatment of statistical mechanics of a proliferating number of hadron species. Below the critical temperature the spins cluster around six special points in the target space known as Weierstrass points. In conclusion, the diversity of compact hyperbolic manifolds suggests that our model is only the simplest example of a broad class of statistical mechanical models whose main features can be understood essentially in geometric terms.« less

  12. Roles of sigma-1 receptors in Alzheimer’s disease

    PubMed Central

    Jin, Jia-Li; Fang, Min; Zhao, Yan-Xin; Liu, Xue-Yuan

    2015-01-01

    Alzheimer’s disease (AD) is a progressive neurodegenerative disorder and the leading cause of senile dementia all over the world. Still no existing drugs can effectively reverse the cognitive impairment. However, Sigma-1 (σ-1) receptors have been long implicated in multiple neurological and psychiatric conditions over these years. In this review, we discuss the current understanding of σ-1 receptor functions. Through regulation of lipid rafts, secretases, kinases, neuroceptors and ion channels, σ-1 receptors can influence cellular signal transduction, TCA cycle, oxidative stress, neuron plasticity and neurotransmitter release etc. Based on this, we suggest the key cellular mechanisms linking σ-1 receptor to Alzheimer’s disease. Besides, we detail the evidences showing that σ-1 receptors agonists, being the promising compounds for treatment of cognitive dysfunction, exhibit robust neuroprotection and anti-amnesia effect against Aβ neurotoxicity in the progress of Alzheimer’s disease. The evidence comes from animal models, preclinical studies in humans and full clinical trials. In addition, the questions to be solved regarding this receptor are also presented. When concerned with NMDAR, σ-1 receptor activation may result in two totally different influences on AD. Utilization of σ-1 agents early in AD remains an overlooked therapeutic opportunity. This article may pave the way for further studies about sigma-1 receptor on Alzheimer’s disease. PMID:26131055

  13. Nonlinear sigma models with compact hyperbolic target spaces

    NASA Astrophysics Data System (ADS)

    Gubser, Steven; Saleem, Zain H.; Schoenholz, Samuel S.; Stoica, Bogdan; Stokes, James

    2016-06-01

    We explore the phase structure of nonlinear sigma models with target spaces corresponding to compact quotients of hyperbolic space, focusing on the case of a hyperbolic genus-2 Riemann surface. The continuum theory of these models can be approximated by a lattice spin system which we simulate using Monte Carlo methods. The target space possesses interesting geometric and topological properties which are reflected in novel features of the sigma model. In particular, we observe a topological phase transition at a critical temperature, above which vortices proliferate, reminiscent of the Kosterlitz-Thouless phase transition in the O(2) model [1, 2]. Unlike in the O(2) case, there are many different types of vortices, suggesting a possible analogy to the Hagedorn treatment of statistical mechanics of a proliferating number of hadron species. Below the critical temperature the spins cluster around six special points in the target space known as Weierstrass points. The diversity of compact hyperbolic manifolds suggests that our model is only the simplest example of a broad class of statistical mechanical models whose main features can be understood essentially in geometric terms.

  14. Neutron Stars and NuSTAR

    NASA Astrophysics Data System (ADS)

    Bhalerao, Varun

    2012-05-01

    My thesis centers around the study of neutron stars, especially those in massive binary systems. To this end, it has two distinct components: the observational study of neutron stars in massive binaries with a goal of measuring neutron star masses and participation in NuSTAR, the first imaging hard X-ray mission, one that is extremely well suited to the study of massive binaries and compact objects in our Galaxy. The Nuclear Spectroscopic Telescope Array (NuSTAR) is a NASA Small Explorer mission that will carry the first focusing high energy X-ray telescope to orbit. NuSTAR has an order-of-magnitude better angular resolution and has two orders of magnitude higher sensitivity than any currently orbiting hard X-ray telescope. I worked to develop, calibrate, and test CdZnTe detectors for NuSTAR. I describe the CdZnTe detectors in comprehensive detail here - from readout procedures to data analysis. Detailed calibration of detectors is necessary for analyzing astrophysical source data obtained by the NuSTAR. I discuss the design and implementation of an automated setup for calibrating flight detectors, followed by calibration procedures and results. Neutron stars are an excellent probe of fundamental physics. The maximum mass of a neutron star can put stringent constraints on the equation of state of matter at extreme pressures and densities. From an astrophysical perspective, there are several open questions in our understanding of neutron stars. What are the birth masses of neutron stars? How do they change in binary evolution? Are there multiple mechanisms for the formation of neutron stars? Measuring masses of neutron stars helps answer these questions. Neutron stars in high-mass X-ray binaries have masses close to their birth mass, providing an opportunity to disentangle the role of "nature" and "nurture" in the observed mass distributions. In 2006, masses had been measured for only six such objects, but this small sample showed the greatest diversity in masses

  15. Time-resolved Spectroscopy of Active Binary Stars

    NASA Astrophysics Data System (ADS)

    Brown, Alexander

    EUVE has provided the first stellar coronal spectra showing individual emission lines, thereby allowing coronal modelling at a level of sophistication previously unattainable. Long EUVE observations have shown the prevalence of large-scale flaring in the coronae of active binary stars. We propose to obtain EUVE DSS spectra and photometry for 8 active binaries, four of which have never been observed by EUVE (EI Eri, AR Psc, V478 Lyr, BY Dra) and four EUV-bright systems that merit reobservation (Sigma CrB, Sigma Gem, Xi UMa, Lambda And). We shall use these observations to derive high quality quiescent coronal spectra for modelling, and to obtain new flare data. We shall try to coordinate these observations with ground-based radio observations and other spacecraft, if the scheduling allows. The proposed observations will significantly increase the available EUVE spectroscopy of active binaries.

  16. [Investigation on spectrum of B 2sigma(+)-X 2sigma+ and C 2pi(r)-X 2sigma+ bands of AlO radical in shock tube].

    PubMed

    Peng, Zhi-Min; Yang, Qian-Suo; Liu, Chun; Zhu, Nai-Yi; Jiang, Zong-Lin

    2010-04-01

    There are some impurities such as aluminum dioxide adhering on the shock tube wall due to the ablating and heating of the aluminum diaphragm by high temperature gas. Under high temperature, the collision of AlO radicals with the gaseous molecules leads to transition of the electronic states and production of strong radiation, which disturb the analysis of radiation spectrum of heated gases in shock tube. In the authors' experiments, the air in the test section with adhering aluminum dioxide was heated to some 4 000-7 000 K, the spectrum of AlO radical was obvious in the range of 460-530 nm, which corresponds to B 2sigma(+)-X 2sigma+ (T00 = 20 689 cm(-1) band. There were several band heads for this band, the interval of neighbor heads was some 2 nm, and all the band heads were with the shortest wavelength. The characteristics of B 2sigma(+)-X 2sigma+ band were explored in experiment and by theory. In addition, the spectrum of C 2pi(r)-X 2sigma+ (T00 = 33 047 cm(-1)) band was also investigated. The corresponding strength was lower than that of B 2sigma(+) -X 2sigma+ band, and the wavelength range of this band was some 270-335 nm where the radiation of A 2sigma(+) -X 2pi (T00 = 32 682 cm(-1)) band of OH radical also existed. This occurrence of the two bands in the same wavelength range is disadvantageous for the spectrum analysis.

  17. The Cambridge Double Star Atlas

    NASA Astrophysics Data System (ADS)

    MacEvoy, Bruce; Tirion, Wil

    2015-12-01

    Preface; What are double stars?; The binary orbit; Double star dynamics; Stellar mass and the binary life cycle; The double star population; Detecting double stars; Double star catalogs; Telescope optics; Preparing to observe; Helpful accessories; Viewing challenges; Next steps; Appendices: target list; Useful formulas; Double star orbits; Double star catalogs; The Greek alphabet.

  18. Aβ mediates Sigma receptor degradation via CaN/NFAT pathway.

    PubMed

    Fang, Min; Zhang, Pei; Zhao, Yanxin; Jin, Aiping; Liu, Xueyuan

    2016-01-01

    Sigma receptor is an endoplasmic reticulum protein and belongs to non-opioid receptor. Increasing evidence shows that Sigma receptor activation can significantly attenuate AD induced neurological dysfunction and the functional deficiency of Sigma receptor plays an important role in the Aβ induced neuronal loss. This study aimed to investigate the influence of extracellular accumulation of Aβ on the Sigma receptor expression. Our results showed the increase in extracellular Aβ had little influence on the mRNA expression of Sigma receptor, but gradually reduced its protein expression. Co-immunoprecipitation was employed to evaluate the interaction of Sigma receptor with other proteins. Results showed BIP could bind to Sigma receptor to affect the ubiquitination of Sigma receptor. Further investigation showed there was a NFAT binding site at the promoter of BIP. Then, Western blot assay was performed to detect NFAT expression. Results showed extracellular Aβ affected the nuclear translocation of NFAT and the CaN activity of NFAT also increased with the accumulation of extracellular Aβ. In this study, NFAT-BIP luciferase reporter gene system was constructed. Results showed NFAT was able to regulate the transcription of BIP. Thus, we speculate that extracellular Aβ accumulation may activate CaN/NFAT signaling pathway to induce chaperone BIP expression, which results in Sigma receptor ubiquitination and its degradation. PMID:27648137

  19. Aβ mediates Sigma receptor degradation via CaN/NFAT pathway.

    PubMed

    Fang, Min; Zhang, Pei; Zhao, Yanxin; Jin, Aiping; Liu, Xueyuan

    2016-01-01

    Sigma receptor is an endoplasmic reticulum protein and belongs to non-opioid receptor. Increasing evidence shows that Sigma receptor activation can significantly attenuate AD induced neurological dysfunction and the functional deficiency of Sigma receptor plays an important role in the Aβ induced neuronal loss. This study aimed to investigate the influence of extracellular accumulation of Aβ on the Sigma receptor expression. Our results showed the increase in extracellular Aβ had little influence on the mRNA expression of Sigma receptor, but gradually reduced its protein expression. Co-immunoprecipitation was employed to evaluate the interaction of Sigma receptor with other proteins. Results showed BIP could bind to Sigma receptor to affect the ubiquitination of Sigma receptor. Further investigation showed there was a NFAT binding site at the promoter of BIP. Then, Western blot assay was performed to detect NFAT expression. Results showed extracellular Aβ affected the nuclear translocation of NFAT and the CaN activity of NFAT also increased with the accumulation of extracellular Aβ. In this study, NFAT-BIP luciferase reporter gene system was constructed. Results showed NFAT was able to regulate the transcription of BIP. Thus, we speculate that extracellular Aβ accumulation may activate CaN/NFAT signaling pathway to induce chaperone BIP expression, which results in Sigma receptor ubiquitination and its degradation.

  20. Aβ mediates Sigma receptor degradation via CaN/NFAT pathway

    PubMed Central

    Fang, Min; Zhang, Pei; Zhao, Yanxin; Jin, Aiping; Liu, Xueyuan

    2016-01-01

    Sigma receptor is an endoplasmic reticulum protein and belongs to non-opioid receptor. Increasing evidence shows that Sigma receptor activation can significantly attenuate AD induced neurological dysfunction and the functional deficiency of Sigma receptor plays an important role in the Aβ induced neuronal loss. This study aimed to investigate the influence of extracellular accumulation of Aβ on the Sigma receptor expression. Our results showed the increase in extracellular Aβ had little influence on the mRNA expression of Sigma receptor, but gradually reduced its protein expression. Co-immunoprecipitation was employed to evaluate the interaction of Sigma receptor with other proteins. Results showed BIP could bind to Sigma receptor to affect the ubiquitination of Sigma receptor. Further investigation showed there was a NFAT binding site at the promoter of BIP. Then, Western blot assay was performed to detect NFAT expression. Results showed extracellular Aβ affected the nuclear translocation of NFAT and the CaN activity of NFAT also increased with the accumulation of extracellular Aβ. In this study, NFAT-BIP luciferase reporter gene system was constructed. Results showed NFAT was able to regulate the transcription of BIP. Thus, we speculate that extracellular Aβ accumulation may activate CaN/NFAT signaling pathway to induce chaperone BIP expression, which results in Sigma receptor ubiquitination and its degradation. PMID:27648137

  1. Aβ mediates Sigma receptor degradation via CaN/NFAT pathway

    PubMed Central

    Fang, Min; Zhang, Pei; Zhao, Yanxin; Jin, Aiping; Liu, Xueyuan

    2016-01-01

    Sigma receptor is an endoplasmic reticulum protein and belongs to non-opioid receptor. Increasing evidence shows that Sigma receptor activation can significantly attenuate AD induced neurological dysfunction and the functional deficiency of Sigma receptor plays an important role in the Aβ induced neuronal loss. This study aimed to investigate the influence of extracellular accumulation of Aβ on the Sigma receptor expression. Our results showed the increase in extracellular Aβ had little influence on the mRNA expression of Sigma receptor, but gradually reduced its protein expression. Co-immunoprecipitation was employed to evaluate the interaction of Sigma receptor with other proteins. Results showed BIP could bind to Sigma receptor to affect the ubiquitination of Sigma receptor. Further investigation showed there was a NFAT binding site at the promoter of BIP. Then, Western blot assay was performed to detect NFAT expression. Results showed extracellular Aβ affected the nuclear translocation of NFAT and the CaN activity of NFAT also increased with the accumulation of extracellular Aβ. In this study, NFAT-BIP luciferase reporter gene system was constructed. Results showed NFAT was able to regulate the transcription of BIP. Thus, we speculate that extracellular Aβ accumulation may activate CaN/NFAT signaling pathway to induce chaperone BIP expression, which results in Sigma receptor ubiquitination and its degradation.

  2. Production of strange secondaries in high-energy {Sigma}{sup -}A collisions

    SciTech Connect

    Arakelyan, G. H.; Kaidalov, A. B.; Merino, C.; Shabelski, Yu. M.

    2011-03-15

    The WA89 Collaboration experimental data on production of {Lambda}, {Sigma}{sup -}, {Sigma}{sup +}, {Xi}{sup -}, {Omega}{sup -} baryons, {Lambda}-bar and {Xi}{sup +} antibaryons in {Sigma}{sup -} collisions with C and Cu targets at 345 GeV/c ({radical}s{sub {Sigma}N} Almost-Equal-To 25.5 GeV) in the frame of the Quark-Gluon String Model is described. The comparison of the theoretical results with the experimental data is discussed. Finally, some relations among the values of the model parameters obtained with the help of quark combinatorics are presented.

  3. Quality assurance and management in microelectronics companies: ISO 9000 versus Six Sigma

    NASA Astrophysics Data System (ADS)

    Lupan, Razvan; Kobi, Abdessamad; Robledo, Christian; Bacivarov, Ioan; Bacivarov, Angelica

    2009-01-01

    A strategy for the implementation of the Six Sigma method as an improvement solution for the ISO 9000:2000 Quality Standard is proposed. Our approach is focused on integrating the DMAIC cycle of the Six Sigma method with the PDCA process approach, highly recommended by the standard ISO 9000:2000. The Six Sigma steps applied to each part of the PDCA cycle are presented in detail, giving some tools and training examples. Based on this analysis the authors conclude that applying Six Sigma philosophy to the Quality Standard implementation process is the best way to achieve the optimal results in quality progress and therefore in customers satisfaction.

  4. Integrating Six Sigma with total quality management: a case example for measuring medication errors.

    PubMed

    Revere, Lee; Black, Ken

    2003-01-01

    Six Sigma is a new management philosophy that seeks a nonexistent error rate. It is ripe for healthcare because many healthcare processes require a near-zero tolerance for mistakes. For most organizations, establishing a Six Sigma program requires significant resources and produces considerable stress. However, in healthcare, management can piggyback Six Sigma onto current total quality management (TQM) efforts so that minimal disruption occurs in the organization. Six Sigma is an extension of the Failure Mode and Effects Analysis that is required by JCAHO; it can easily be integrated into existing quality management efforts. Integrating Six Sigma into the existing TQM program facilitates process improvement through detailed data analysis. A drilled-down approach to root-cause analysis greatly enhances the existing TQM approach. Using the Six Sigma metrics, internal project comparisons facilitate resource allocation while external project comparisons allow for benchmarking. Thus, the application of Six Sigma makes TQM efforts more successful. This article presents a framework for including Six Sigma in an organization's TQM plan while providing a concrete example using medication errors. Using the process defined in this article, healthcare executives can integrate Six Sigma into all of their TQM projects.

  5. [Physiological functions of sigma-1 receptors and its relation to psychic dependence].

    PubMed

    Mori, Tomohisa; Yoshizawa, Kazumi; Shibasaki, Masahiro; Suzuki, Tsutomu

    2012-12-01

    Sigma-1 receptors had been believed as a one of the opioid receptors. Recent reports have demonstrated that the sigma-1 receptor is a nonopioid receptor that resides specifically at the endoplasmic reticulum (ER)-mitochondrion interface and has been shown to be protective against neurodegeneration as an ER chaperone. In this review, we review the molecular mechanism on the cytoprotective effects of sigma-1 receptors. Furthermore, we summarize the effects of sigma-1 receptor ligand on the behavioral effects, especially on the reward-related behaviors induced by psychostimulants. The ER is a major locus for the synthesis of proteins. Under physiological conditions, the overall protein level in the ER is maintained by a balance between the protein synthesis and degradation. When the balance is perturbed, signaling pathways (the unfolded protein response (UPR) caused by ER stress or the ER overload response (EOR)) are activated to regulate the cell survival/death signalings. Sigma-1 receptor could be upregulated by ER stress and EOR, and that upregulated sigma-1 receptors attenuate UPR and EOR by increasing the chaperone activity of sigma-1 receptors and attenuation of prossessed NF-kappaB activity, respectively. On the other hand, even sigma-1 receptor could be upregulated by self-administration of methamphetamine in the ventral tegmental area, exact mechanism how sigma-1 receptor chaperone affect the behavioral effects induced by psychostimulants is not yet cleared. However, the prototypic sigma-1 receptor agonist SKF10,047 induces psychotomimetic effects, and psychotomimetic-like discriminative stimulus effects are at least in part mediated by sigma-1 receptors. Recent research showed that endogenous hallucinogen (N,N-dimethyltryptamine) might be a sigma-1 receptor regulator, indicating that sigma-1 receptor is crosely related to psychotomimetic effects. Furthermore, sigma-1 receptor agonist can enhance the discriminative stimulus effects of psychostimulants, and

  6. MOLECULAR GAS AND STAR FORMATION IN NEARBY DISK GALAXIES

    SciTech Connect

    Leroy, Adam K.; Munoz-Mateos, Juan-Carlos; Walter, Fabian; Sandstrom, Karin; Meidt, Sharon; Rix, Hans-Walter; Schinnerer, Eva; Schruba, Andreas; Bigiel, Frank; Bolatto, Alberto; Brinks, Elias; De Blok, W. J. G.; Rosolowsky, Erik; Schuster, Karl-Friedrich; Usero, Antonio

    2013-08-01

    We compare molecular gas traced by {sup 12}CO (2-1) maps from the HERACLES survey, with tracers of the recent star formation rate (SFR) across 30 nearby disk galaxies. We demonstrate a first-order linear correspondence between {Sigma}{sub mol} and {Sigma}{sub SFR} but also find important second-order systematic variations in the apparent molecular gas depletion time, {tau}{sub dep}{sup mol}={Sigma}{sub mol}/{Sigma}{sub SFR}. At the 1 kpc common resolution of HERACLES, CO emission correlates closely with many tracers of the recent SFR. Weighting each line of sight equally, using a fixed {alpha}{sub CO} equivalent to the Milky Way value, our data yield a molecular gas depletion time, {tau}{sub dep}{sup mol}={Sigma}{sub mol}/{Sigma}{sub SFR}{approx}2.2 Gyr with 0.3 dex 1{sigma} scatter, in very good agreement with recent literature data. We apply a forward-modeling approach to constrain the power-law index, N, that relates the SFR surface density and the molecular gas surface density, {Sigma}{sub SFR}{proportional_to}{Sigma}{sub mol}{sup N}. We find N = 1 {+-} 0.15 for our full data set with some scatter from galaxy to galaxy. This also agrees with recent work, but we caution that a power-law treatment oversimplifies the topic given that we observe correlations between {tau}{sub dep}{sup mol} and other local and global quantities. The strongest of these are a decreased {tau}{sub dep}{sup mol} in low-mass, low-metallicity galaxies and a correlation of the kpc-scale {tau}{sub dep}{sup mol} with dust-to-gas ratio, D/G. These correlations can be explained by a CO-to-H{sub 2} conversion factor ({alpha}{sub CO}) that depends on dust shielding, and thus D/G, in the theoretically expected way. This is not a unique interpretation, but external evidence of conversion factor variations makes this the most conservative explanation of the strongest observed {tau}{sub dep}{sup mol} trends. After applying a D/G-dependent {alpha}{sub CO}, some weak correlations between {tau}{sub dep

  7. On the A-dependence of {sigma}{sub L}/{sigma}{sub T}: Skeletons in the shadow

    SciTech Connect

    Milana, J.

    1994-04-01

    A most counter-intuitive dependence in the differential cross-section in the shadowing regime is shown to result from a higher-twist nuclear enhancement in R = {sigma}{sub L}/{sigma}{sub T} which severely complicates the unravelling from present data the corresponding dependence in Q{sup 2} of the nuclear structure functions, F{sub 2}{sup A}(x,Q{sup 2}). Indeed, until precision measurements close this loophole, the extrapolations of the structure functions to either higher Q{sup 2} or other processes (as is necessary to address present data at FNAL or future experiments at RHIC) must be considered problematic. The contribution CEBAF can make in this regard by providing systematic determination of R{sub A}(x, Q{sup 2}) is thus emphasized. The purpose of this talk is to motivate an experiment CEBAF can and should do, especially if upgraded to higher energies. While providing information on nuclear structure that is interesting in itself, the added motivation is that precision results will have important impact on other high-energy experiments involving nuclear targets that have been, and will continue to be done all over the world.

  8. Understanding the participation of quadricyclane as nucleophile in polar [2sigma + 2sigma + 2pi] cycloadditions toward electrophilic pi molecules.

    PubMed

    Domingo, Luis R; Saéz, José A; Zaragozá, Ramón J; Arnó, Manuel

    2008-11-21

    The formal [2sigma + 2sigma + 2pi] cycloaddition of quadricyclane, 1, with dimethyl azodicarboxylate, 2, in water has been studied using DFT methods at the B3LYP/6-31G** and MPWB1K/6-31G** levels. In the gas phase, the reaction of 1 with 2 has a two-stage mechanism with a large polar character and an activation barrier of 23.2 kcal/mol. Inclusion of water through a combined discrete-continuum model changes the mechanism to a two-step model where the first nucleophilic attack of 1 to 2 is the rate-limiting step with an activation barrier of 14.7 kcal/mol. Analysis of the electronic structure of the transition state structures points out the large zwitterionic character of these species. A DFT analysis of the global electrophilicity and nucleophilicity of the reagents provides a sound explanation about the participation of 1 as a nucleophile in these cycloadditions. This behavior is reinforced by a further study of the reaction of 1 with 1,1-dicyanoethylene.

  9. The structure of young star clusters

    NASA Astrophysics Data System (ADS)

    Gladwin, P. P.; Kitsionas, S.; Boffin, H. M. J.; Whitworth, A. P.

    1999-01-01

    In this paper we analyse and compare the clustering of young stars in Chamaeleon I and Taurus. We compute the mean surface density of companion stars N as a function of angular displacement theta from each star. We then fit N theta) with two simultaneous power laws, i.e. N(theta) ~ K_bintheta^-beta_bin + K_clutheta^-beta_clu. For Chamaeleon I, we obtain beta_bin= 1.97 +/- and beta_clu= 0.28 +/- 0.06, with the elbow at theta_elb~ 0 011 +/- 0 004. For Taurus, we obtain beta_bin= 2.02 +/- 0.04 and beta _clu= 0.87 +/- 0.01, with the elbow at theta _elb~ 0 013 +/- 0 003. For both star clusters the observational data make large (~ 5 sigma) systematic excursions from the best-fitting curve in the binary regime (theta < theta_elb). These excursions are visible also in the data used by Larson and Simon, and may be attributable to evolutionary effects of the types discussed recently by Nakajima et al. and Bate et al. In the clustering regime (theta > theta_elb) the data conform to the best-fitting curve very well, but the beta_clu values we obtain differ significantly from those obtained by other workers. These differences are due partly to the use of different samples, and partly to different methods of analysis. We also calculate the box dimensions for the two star clusters: for Chamaeleon I we obtain D_box~=1.51+/-0.12, and for Taurus D_box~=1.39+/-0.01. However, the limited dynamic range makes these estimates simply descriptors of the large-scale clustering, and not admissible evidence for fractality. We propose two algorithms for objectively generating maps of constant stellar surface density in young star clusters. Such maps are useful for comparison with molecular-line and dust-continuum maps of star-forming clouds, and with the results of numerical simulations of star formation. They are also useful because they retain information that is suppressed in the evaluation of N(theta). Algorithm I (SCATTER) uses a universal smoothing length, and therefore has a restricted

  10. Time-resolved Spectroscopy of Active Binary Stars: Coronal Structure and Flares (Part II)

    NASA Astrophysics Data System (ADS)

    Brown, Alexander

    EUVE has provided the first stellar coronal spectra showing individual emission lines, thereby allowing coronal modelling at a level of sophistication previously unattainable. Long EUVE observations have shown that large-scale flaring is prevalent in the coronae of active binary stars. We propose to obtain EUVE DSS spectra and photometry for 4 active binaries, one of which has never been observed by EUVE (V478 Lyr) and three EUV-bright systems that merit reobservation (Sigma CrB, Sigma Gem, Xi UMa). We shall use these observations to derive high quality quiescent coronal spectra for measuring emission measure distributions and modelling, and to obtain new flare data. We shall try to coordinate these observations with ground-based radio observations and other spacecraft, if the scheduling allows. The Sigma CrB spectra may be coordinated with AXAF GTO observations. The proposed observations will significantly increase the available EUVE spectroscopy of active binaries.

  11. THE CURRENT STAR FORMATION RATE OF K+A GALAXIES

    SciTech Connect

    Nielsen, Danielle M.; Ridgway, Susan E.; De Propris, Roberto; Goto, Tomotsugu

    2012-12-20

    We derive the stacked 1.4 GHz flux from the FIRST survey for 811 K+A galaxies selected from the Sloan Digital Sky Survey Data Release 7. For these objects we find a mean flux density of 56 {+-} 9 {mu}Jy. A similar stack of radio-quiet white dwarfs yields an upper limit of 43 {mu}Jy at a 5{sigma} significance to the flux in blank regions of the sky. This implies an average star formation rate of 1.6 {+-} 0.3 M{sub Sun} yr{sup -1} for K+A galaxies. However, the majority of the signal comes from {approx}4% of K+A fields that have aperture fluxes above the 5{sigma} noise level of the FIRST survey. A stack of the remaining galaxies shows little residual flux consistent with an upper limit on star formation of 1.3 M{sub Sun} yr{sup -1}. Even for a subset of 456 'young' (spectral ages <250 Myr) K+A galaxies, we find that the stacked 1.4 GHz flux is consistent with no current star formation. Our data suggest that the original starburst has been terminated in the majority of K+A galaxies, but that this may represent part of a duty cycle where a fraction of these galaxies may be active at a given moment with dusty starbursts and active galactic nuclei being present.

  12. The Millennium Star Atlas

    NASA Astrophysics Data System (ADS)

    Sinnott, R. W.

    1997-08-01

    Derived from Hipparcos and Tycho observations, the Millennium Star Atlas is a set of 1548 charts covering the entire sky to about magnitude 11. It stands apart from all previous printed atlases in completeness to magnitude 10 and in uniformity around the sky. The generous chart scale has made possible a number of innovations never before seen in a star atlas: arrows on high-proper-motion stars, double-star ticks conveying separation and position angle for a specific modern epoch, distance labels for nearby stars, and variable stars coded by amplitude, period, and type. Among the nonstellar objects plotted, more than 8000 galaxies are shown with aspect ratio and orientation.

  13. The Pistol Star

    NASA Astrophysics Data System (ADS)

    Najarro, F.; Figer, D. F.

    1998-06-01

    Results of an spectroscopic investigation of the Pistol star are presented. The near-infrared spectra and photometry data are fit with stellar wind models to find that the star is extraordinarily luminous, L = 106.7±0.5 L⊙, making it one of the most luminous stars known. Coupled with the relatively cool temperature, Teff = 10^{4.17_{ - 0.06}^{ + 0.19} } K, the star is clearly in violation of the Humphreys-Davidson limit. The derived line of sight velocity of the star assures its membership in the Quintuplet cluster. This, along with the inferred extinction, places the star at the Galactic Center.

  14. WISE DETECTIONS OF DUST IN THE HABITABLE ZONES OF PLANET-BEARING STARS

    SciTech Connect

    Morales, Farisa Y.; Bryden, G.; Werner, M. W.; Padgett, D. L.; Furlan, E.

    2012-09-20

    We use data from the Wide-field Infrared Survey Explorer (WISE) all-sky release to explore the incidence of warm dust in the habitable zones around exoplanet-host stars. Dust emission at 12 and/or 22 {mu}m (T{sub dust} {approx} 300 and/or {approx}150 K) traces events in the terrestrial planet zones; its existence implies replenishment by evaporation of comets or collisions of asteroids, possibly stirred by larger planets. Of the 591 planetary systems (728 extrasolar planets) in the Exoplanet Encyclopaedia as of 2012 January 31, 350 are robustly detected by WISE at {>=}5{sigma} level. We perform detailed photosphere subtraction using tools developed for Spitzer data and visually inspect all the WISE images to confirm bona fide point sources. We find nine planet-bearing stars show dust excess emission at 12 and/or 22 {mu}m at {>=}3{sigma} level around young, main-sequence, or evolved giant stars. Overall, our results yield an excess incidence of {approx}2.6% for stars of all evolutionary stages, but {approx}1% for planetary debris disks around main-sequence stars. Besides recovering previously known warm systems, we identify one new excess candidate around the young star UScoCTIO 108.

  15. Clumping-corrected mass-loss rates of Wolf-Rayet stars

    NASA Astrophysics Data System (ADS)

    Nugis, T.; Crowther, P. A.; Willis, A. J.

    1998-05-01

    Mass-loss rates of Galactic Wolf-Rayet stars have been determined from their radio emission power and spectral index (alpha = dln {f_ν} / dln ν), accounting for the clumped structure and (potential) variable ionization in their outer winds. The average spectral index between mm- and cm- wavelengths is ~ 0.77 for WN stars and ~ 0.75 for WC stars, in contrast with ~ 0.58 expected for smooth winds. The observed wavelength dependence of alpha can be explained using clumped wind models in some cases, with shocks (at 30-100 stellar radii) producing a higher ionization zone in the outer wind. We obtain an empirical formula relating mass-loss with observed optical emission line equivalent widths, with application to stars without measured radio fluxes. Clumping-corrected mass-loss rates are generally lower than those obtained by current smooth wind models. Specifically we find log \\mdot(clumpy)-log \\mdot(smooth)=-0.19 (sigma=0.28) for WN stars, and log \\mdot(clumpy)-log \\mdot(smooth)=-0.62 (sigma=0.19) for WC stars. New mass-loss rate estimates agree very well with (clumping independent) determinations of WR components in binary systems.

  16. WISE Detections of Dust in the Habitable Zones of Planet-Bearing Stars

    NASA Technical Reports Server (NTRS)

    Morales, Farisa Y.; Padgett, Deborah L.; Bryden, Geoffrey; Werner, M. W.; Furlan, E.

    2012-01-01

    We use data from the Wide-field Infrared Survey Explorer (WISE) all-sky release to explore the incidence of warm dust in the habitable zones around exoplanet-host stars. Dust emission at 12 and/or 22 microns (T(sub dust) approx.300 and/or approx.150 K) traces events in the terrestrial planet zones; its existence implies replenishment by evaporation of comets or collisions of asteroids, possibly stirred by larger planets. Of the 591 planetary systems (728 extrasolar planets) in the Exoplanet Encyclopedia as of 2012 January 31, 350 are robustly detected by WISE at > or = 5(sigma) level. We perform detailed photosphere subtraction using tools developed for Spitzer data and visually inspect all the WISE images to confirm bona fide point sources. We find nine planet-bearing stars show dust excess emission at 12 and/or 22 microns at > or = 3(sigma) level around young, main-sequence, or evolved giant stars. Overall, our results yield an excess incidence of approx.2.6% for stars of all evolutionary stages, but approx.1% for planetary debris disks around main-sequence stars. Besides recovering previously known warm systems, we identify one new excess candidate around the young star UScoCTIO 108.

  17. A simple predictive model of chemical potentials: H sub 2 ( sup 1. Sigma. sub g ) and Li sub 2 ( sup 1. Sigma. sub g )

    SciTech Connect

    Tang, K.T.; Toennies, J.P. ); Meyer, W. )

    1991-07-15

    A simple model for van der Waals potentials presented earlier (J. Chem. Phys. {bold 80}, 3726 (1984)) has been extended to describe chemical bonds by including the exchange-dispersion term of Herring and Flicker. For H{sub 2}, the {sup 1}{Sigma} ground state potential is predicted in excellent agreement with the accurately known {ital ab} {ital initio} potential, the well depth being reproduced to within 0.6%. New two configuration self-consistent-field (SCF) calculations for the {sup 1}{Sigma} and the {sup 3}{Sigma} states of Li{sub 2} have made it possible to test the model for this system as well. Here the discrepancy is only 3% in the well depth for the {sup 1}{Sigma} Li{sub 2} potential.

  18. The /A 1 Sigma +/ - /X 1 Sigma +/ system of the isotopic lithium hydrides - The molecular constants, potential energy curves, and their adiabatic corrections

    NASA Technical Reports Server (NTRS)

    Vidal, C. R.; Stwalley, W. C.

    1982-01-01

    The molecular constants and their adiabatic corrections have been determined for the (A 1 Sigma +) - (X 1 Sigma +) system of the isotopic lithium hydrides: (Li-6)H, (Li-7)H, (Li-6)D, and (Li-7)D. Using a fully quantum mechanical variational method, the potential energy curves (IPA potentials) are determined. Extending the variational method, we have obtained for the first time adiabatic corrections of potential energy curves from isotopic spectroscopic data. A significant difference between the potential energy curves of the lithium hydrides and the lithium deuterides has been observed. When Li-6 was replaced by Li-7, a significant difference was only observed for the (A 1 Sigma +) state, but not for the (X 1 Sigma +) state.

  19. Reservoir continuous process improvement six sigma methodology implementation

    SciTech Connect

    Wannamaker, A.L.

    1996-12-01

    The six sigma methodology adopted by AlliedSignal Inc. for implementing continuous improvement activity was applied to a new manufacturing assignment for Federal Manufacturing & Technologies (FM&T). The responsibility for reservoir development/production was transferred from Rocky Flats to FM&T. Pressure vessel fabrication was new to this facility. No fabrication history for this type of product existed in-house. Statistical tools such as process mapping, failure mode and effects analysis, and design of experiments were used to define and fully characterize the machine processes to be used in reservoir production. Continuous improvement with regard to operating efficiencies and product quality is an ongoing activity at FM&T.

  20. Interference Resilient Sigma Delta-Based Pulse Oximeter.

    PubMed

    Shokouhian, Mohsen; Morling, Richard; Kale, Izzet

    2016-06-01

    Ambient light and optical interference can severely affect the performance of pulse oximeters. The deployment of a robust modulation technique to drive the pulse oximeter LEDs can reduce these unwanted effects and increases the resilient of the pulse oximeter against artificial ambient light. The time division modulation technique used in conventional pulse oximeters can not remove the effect of modulated light coming from surrounding environment and this may cause huge measurement error in pulse oximeter readings. This paper presents a novel cross-coupled sigma delta modulator which ensures that measurement accuracy will be more robust in comparison with conventional fixed-frequency oximeter modulation technique especially in the presence of pulsed artificial ambient light. Moreover, this novel modulator gives an extra control over the pulse oximeter power consumption leading to improved power management.

  1. Interference Resilient Sigma Delta-Based Pulse Oximeter.

    PubMed

    Shokouhian, Mohsen; Morling, Richard; Kale, Izzet

    2016-06-01

    Ambient light and optical interference can severely affect the performance of pulse oximeters. The deployment of a robust modulation technique to drive the pulse oximeter LEDs can reduce these unwanted effects and increases the resilient of the pulse oximeter against artificial ambient light. The time division modulation technique used in conventional pulse oximeters can not remove the effect of modulated light coming from surrounding environment and this may cause huge measurement error in pulse oximeter readings. This paper presents a novel cross-coupled sigma delta modulator which ensures that measurement accuracy will be more robust in comparison with conventional fixed-frequency oximeter modulation technique especially in the presence of pulsed artificial ambient light. Moreover, this novel modulator gives an extra control over the pulse oximeter power consumption leading to improved power management. PMID:26742140

  2. Lean Six Sigma Application in Rear Combination Automotive Lighting Process

    NASA Astrophysics Data System (ADS)

    Sodkomkham, Thanwarhat; Chutima, Parames

    2016-05-01

    The case study company produces various front and rear lightings for automobiles and motorcycles. Currently, it faces two problems, i.e. high defective rate and high inventory. Lean Six Sigma was applied as a tool to solve the first problem, whereas the other problem was managed by changing the production concept from push to pull. The results showed that after applying all new settings to the process, the defect rate was reduced from 36,361 DPPM to 3,029 DPPM. In addition, after the implementation of the Kanban system, the company achieved substantial improvement in lead time reduction by 44%, in-process inventory reduction by 42%, finished good inventory reduction by 50%, and finished good area increased by 16%.

  3. Vainshtein mechanism in massive gravity nonlinear sigma models

    NASA Astrophysics Data System (ADS)

    Aoki, Katsuki; Mizuno, Shuntaro

    2016-09-01

    We study the stability of the Vainshtein screening solution of massive gravity/bigravity based on the massive nonlinear sigma model as the effective action inside the Vainshtein radius. The effective action is obtained by taking the Λ2 decoupling limit around a curved spacetime. First we derive a general consequence that any Ricci flat Vainshtein screening solution is unstable when we take into account the excitation of the scalar graviton only. This instability suggests that the nonlinear excitation of the scalar graviton is not sufficient to obtain a successful Vainshtein screening in massive gravity/bigravity. Then to see the role of the excitation of the vector graviton, we study perturbations around the static and spherically symmetric solution obtained in bigravity explicitly. As a result, we find that linear excitations of the vector graviton cannot be helpful and the solution still suffers from a ghost and/or a gradient instability for any parameters of the theory for this background.

  4. Hybridization of a sigma-delta-based CMOS hybrid detector

    NASA Astrophysics Data System (ADS)

    Kolb, K. E.; Stoffel, N. C.; Douglas, B.; Maloney, C. W.; Raisanen, A. D.; Ashe, B.; Figer, D. F.; Tamagawa, T.; Halpern, B.; Ignjatovic, Zeljko

    2010-07-01

    The Rochester Imaging Detector Laboratory, University of Rochester, Infotonics Technology Center, and Jet Process Corporation developed a hybrid silicon detector with an on-chip sigma-delta (ΣΔ) ADC. This paper describes the process and reports the results of developing a fabrication process to robustly produce high-quality bump bonds to hybridize a back-illuminated detector with its ΣΔ ADC. The design utilizes aluminum pads on both the readout circuit and the photodiode array with interconnecting indium bumps between them. The development of the bump bonding process is discussed, including specific material choices, interim process structures, and final functionality. Results include measurements of bond integrity, cross-wafer uniformity of indium bumps, and effects of process parameters on the final product. Future plans for improving the bump bonding process are summarized.

  5. Chaotic inflation from nonlinear sigma models in supergravity

    NASA Astrophysics Data System (ADS)

    Hellerman, Simeon; Kehayias, John; Yanagida, Tsutomu T.

    2015-03-01

    We present a common solution to the puzzles of the light Higgs or quark masses and the need for a shift symmetry and large field values in high scale chaotic inflation. One way to protect, for example, the Higgs from a large supersymmetric mass term is if it is the Nambu-Goldstone boson (NGB) of a nonlinear sigma model. However, it is well known that nonlinear sigma models (NLSMs) with nontrivial Kähler transformations are problematic to couple to supergravity. An additional field is necessary to make the Kähler potential of the NLSM invariant in supergravity. This field must have a shift symmetry - making it a candidate for the inflaton (or axion). We give an explicit example of such a model for the coset space SU (3) / SU (2) × U (1), with the Higgs as the NGB, including breaking the inflaton's shift symmetry and producing a chaotic inflation potential. This construction can also be applied to other models, such as one based on E7 / SO (10) × U (1) × U (1) which incorporates the first two generations of (light) quarks as the Nambu-Goldstone multiplets, and has an axion in addition to the inflaton. Along the way we clarify and connect previous work on understanding NLSMs in supergravity and the origin of the extra field (which is the inflaton here), including a connection to Witten-Bagger quantization. This framework has wide applications to model building; a light particle from a NLSM requires, in supergravity, exactly the structure for chaotic inflaton or an axion.

  6. PHIBSS: MOLECULAR GAS, EXTINCTION, STAR FORMATION, AND KINEMATICS IN THE z = 1.5 STAR-FORMING GALAXY EGS13011166

    SciTech Connect

    Genzel, R.; Tacconi, L. J.; Kurk, J.; Wuyts, S.; Foerster Schreiber, N. M.; Gracia-Carpio, J.; Combes, F.; Freundlich, J.; Bolatto, A.; Cooper, M. C.; Neri, R.; Nordon, R.; Bournaud, F.; Comerford, J.; Cox, P.; Davis, M.; Garcia-Burillo, S.; Naab, T.; Lutz, D. E-mail: linda@mpe.mpg.de; and others

    2013-08-10

    We report matched resolution imaging spectroscopy of the CO 3-2 line (with the IRAM Plateau de Bure millimeter interferometer) and of the H{alpha} line (with LUCI at the Large Binocular Telescope) in the massive z = 1.53 main-sequence galaxy EGS 13011166, as part of the ''Plateau de Bure high-z, blue-sequence survey'' (PHIBSS: Tacconi et al.). We combine these data with Hubble Space Telescope V-I-J-H-band maps to derive spatially resolved distributions of stellar surface density, star formation rate, molecular gas surface density, optical extinction, and gas kinematics. The spatial distribution and kinematics of the ionized and molecular gas are remarkably similar and are well modeled by a turbulent, globally Toomre unstable, rotating disk. The stellar surface density distribution is smoother than the clumpy rest-frame UV/optical light distribution and peaks in an obscured, star-forming massive bulge near the dynamical center. The molecular gas surface density and the effective optical screen extinction track each other and are well modeled by a ''mixed'' extinction model. The inferred slope of the spatially resolved molecular gas to star formation rate relation, N = dlog{Sigma}{sub starform}/dlog{Sigma}{sub molgas}, depends strongly on the adopted extinction model, and can vary from 0.8 to 1.7. For the preferred mixed dust-gas model, we find N = 1.14 {+-} 0.1.

  7. Modeling of trace constituent transport with the University of Wisconsin global isentropic-sigma model

    SciTech Connect

    Zapotocny, T.H.; Johnson, D.R.; Reames, F.M.

    1994-06-01

    The main goal of this report is to demonstrate the ability of the University of Wisconsin (UW) hybrid isentropic-sigma ({theta}-{sigma}) model for global NWP, especially the global distribution of precipitation and simulating the long-range transport of an inert trace constituent. Results from this prototype climate model are compared against the results of a nominally identical global {sigma} model in order to establish the relative advantages and disadvantages of each coordinate system for simulating long-range transport processes. The current work is an extension of works by Johnson et al. and Zapotocny et al. The first study used analytically specified initial conditions for {theta}-{sigma} and {sigma} coordinate channel models, the second study incorporated observed data into regional versions of both models, while the third study documented the first global results with the UW {theta}-{sigma} model. Section 2 of this report describes additions to the UW {theta}-{sigma} model since the Zapotocny et al. study, Section 3 evaluates a five day precipitation forecast produced by the UW {theta}-{sigma} model and presents a comparison of each model`s ability to prognostically simulate and conserve an inert trace constituent. A summary is presented in Section 4.

  8. Facilitating Teamwork with Lean Six Sigma and Web-Based Technology

    ERIC Educational Resources Information Center

    Krause, Tim

    2009-01-01

    In this article, the author outlines a variety of ways of defining, making explicit, and supporting effective team-based projects through the basic tenets of Lean Six Sigma and the use of Web-based technologies. A combination of Lean Six Sigma and a handful of project management technologies not only help in fostering the communication central to…

  9. Improving Self Service the Six Sigma Way at Newcastle University Library

    ERIC Educational Resources Information Center

    Kumi, Susan; Morrow, John

    2006-01-01

    Purpose: To report on the collaborative project between Newcastle University Library and 3M which aimed to increase self-issue levels using six sigma methodology. Design/methodology/approach: The six-month long project is outlined and gives an insight into the process improvement methodology called six sigma. An explanation of why we ran the…

  10. Using Six Sigma for Performance Improvement in Business Curriculum: A Case Study

    ERIC Educational Resources Information Center

    Kukreja, Anil; Ricks, Joe M., Jr.; Meyer, Jean A.

    2009-01-01

    During the last few decades, a number of quality improvement methodologies have been used by organizations. This article provides a brief review of the quality improvement literature related to academia and a case study using Six Sigma methodology to analyze students' performance in a standardized examination. We found Six Sigma to be an effective…

  11. Electronic contributions to the sigma(p) parameter of the Hammett equation.

    PubMed

    Domingo, Luis R; Pérez, Patricia; Contreras, Renato

    2003-07-25

    A statistical procedure to obtain the intrinsic electronic contributions to the Hammett substituent constant sigma(p) is reported. The method is based on the comparison between the experimental sigma(p) values and the electronic electrophilicity index omega evaluated for a series of 42 functional groups commonly present in organic compounds.

  12. Activation of sigma-1 receptor chaperone in the treatment of neuropsychiatric diseases and its clinical implication.

    PubMed

    Hashimoto, Kenji

    2015-01-01

    Endoplasmic reticulum (ER) protein sigma-1 receptor represents unique chaperone activity in the central nervous system, and it exerts a potent influence on a number of neurotransmitter systems. Several lines of evidence suggest that activation of sigma-1 receptor plays a role in the pathophysiology of neuropsychiatric diseases, as well as in the mechanisms of some therapeutic drugs and neurosteroids. Preclinical studies showed that some selective serotonin reuptake inhibitors (SSRIs; fluvoxamine, fluoxetine, excitalopram), donepezil, and ifenprodil act as sigma-1 receptor agonists. Furthermore, sigma-1 receptor agonists could improve the N-methyl-D-aspartate (NMDA) antagonist phencyclidine (PCP)-induced cognitive deficits in mice. A study using positron emission tomography have demonstrated that an oral administration of fluvoxamine or donepezil could bind to sigma-1 receptor in the healthy human brain, suggesting that sigma-1 receptor might be involved in the therapeutic mechanisms of these drugs. Moreover, case reports suggest that sigma-1 receptor agonists, including fluvoxamine, and ifenprodil, may be effective in the treatment of cognitive impairment in schizophrenia, delirium in elderly people, and flashbacks in post-traumatic stress disorder. In this review article, the author would like to discuss the clinical implication of sigma-1 receptor agonists, including endogenous neurosteroids, in the neuropsychiatric diseases.

  13. Teaching Lean Six Sigma within a Supply Chain Context: The Airplane Supply Chain Simulation

    ERIC Educational Resources Information Center

    Ellis, Scott C.; Goldsby, Thomas J.; Bailey, Ana M.; Oh, Jae-Young

    2014-01-01

    Lean six sigma is a management methodology that firms can employ to achieve substantial improvement in supply chain performance. However, few pedagogical exercises facilitate students' use of a comprehensive set of lean six sigma principles within a supply chain context. We describe the Airplane Supply Chain Simulation that helps students…

  14. The Treatment of Six Sigma in Introductory Operations Management Textbooks: Clearing Up the Confusion

    ERIC Educational Resources Information Center

    Ravinder, Handanhal; Misra, Ram B.

    2016-01-01

    This paper critically examines the treatment of the statistical basis for Six Sigma and process capability in popular operations management textbooks. It discusses areas of confusion and suggest ways of treating the topic that make sense to instructors as well as students. Even though Six Sigma was introduced almost 30 years ago, misconceptions…

  15. The Streptomyces coelicolor developmental transcription factor sigmaBldN is synthesized as a proprotein.

    PubMed

    Bibb, Maureen J; Buttner, Mark J

    2003-04-01

    bldN is one of a set of genes required for the formation of specialized, spore-bearing aerial hyphae during differentiation in the mycelial bacterium Streptomyces coelicolor. Previous analysis (M. J. Bibb et al., J. Bacteriol. 182:4606-4616, 2000) showed that bldN encodes a member of the extracytoplasmic function subfamily of RNA polymerase sigma factors and that translation from the most strongly predicted start codon (GTG(1)) would give rise to a sigma factor having an unusual N-terminal extension of ca. 86 residues. Here, by using a combination of site-directed mutagenesis and immunoblot analysis, we provide evidence that all bldN translation arises from initiation at GTG(1) and that the primary translation product is a proprotein (pro-sigma(BldN)) that is proteolytically processed to a mature species (sigma(BldN)) by removal of most of the unusual N-terminal extension. A time course taken during differentiation of the wild type on solid medium showed early production of pro-sigma(BldN) and the subsequent appearance of mature sigma(BldN), which was concomitant with aerial mycelium formation and the disappearance of pro-sigma(BldN). Two genes encoding members of a family of metalloproteases that are involved in the regulated proteolytic processing of transcription factors in other organisms were identified in the S. coelicolor genome, but their disruption did not affect differentiation or pro-sigma(BldN) processing.

  16. Intrinsically variable stars

    NASA Technical Reports Server (NTRS)

    Bohm-Vitense, Erika; Querci, Monique

    1987-01-01

    The characteristics of intrinsically variable stars are examined, reviewing the results of observations obtained with the IUE satellite since its launch in 1978. Selected data on both medium-spectral-class pulsating stars (Delta Cep stars, W Vir stars, and related groups) and late-type variables (M, S, and C giants and supergiants) are presented in spectra, graphs, and tables and described in detail. Topics addressed include the calibration of the the period-luminosity relation, Cepheid distance determination, checking stellar evolution theory by the giant companions of Cepheids, Cepheid masses, the importance of the hydrogen convection zone in Cepheids, temperature and abundance estimates for Population II pulsating stars, mass loss in Population II Cepheids, SWP and LWP images of cold giants and supergiants, temporal variations in the UV lines of cold stars, C-rich cold stars, and cold stars with highly ionized emission lines.

  17. Star Formation in Galaxies

    NASA Technical Reports Server (NTRS)

    1987-01-01

    Topics addressed include: star formation; galactic infrared emission; molecular clouds; OB star luminosity; dust grains; IRAS observations; galactic disks; stellar formation in Magellanic clouds; irregular galaxies; spiral galaxies; starbursts; morphology of galactic centers; and far-infrared observations.

  18. Astrophysics: Stars fight back

    NASA Astrophysics Data System (ADS)

    Hopkins, Philip F.

    2014-12-01

    Galaxies contain fewer stars than predicted. The discovery of a massive galactic outflow of molecular gas in a compact galaxy, which forms stars 100 times faster than the Milky Way, may help to explain why. See Letter p.68

  19. 'Polaris, Mark Kummerfeldt's Star, and My Star.'

    ERIC Educational Resources Information Center

    McLure, John W.

    1984-01-01

    In most astronomy courses, descriptions of stars and constellations reveal the western European origins of the astronomers who named them. However, it is suggested that a study of non-western views be incorporated into astronomy curricula. Descriptions of various stars and constellations from different cultures and instructional strategies are…

  20. Chromospheres of Coronal Stars

    NASA Technical Reports Server (NTRS)

    Linsky, Jeffrey L.; Wood, Brian E.

    1996-01-01

    We summarize the main results obtained from the analysis of ultraviolet emission line profiles of coronal late-type stars observed with the Goddard High Resolution Spectrograph (GHRS) on the Hubble Space Telescope. The excellent GHRS spectra provide new information on magnetohydrodynamic phenomena in the chromospheres and transition regions of these stars. One exciting new result is the discovery of broad components in the transition region lines of active stars that we believe provide evidence for microflare heating in these stars.

  1. Dibaryons in neutron stars

    NASA Technical Reports Server (NTRS)

    Olinto, Angela V.; Haensel, Pawel; Frieman, Joshua A.

    1991-01-01

    The effects are studied of H-dibaryons on the structure of neutron stars. It was found that H particles could be present in neutron stars for a wide range of dibaryon masses. The appearance of dibaryons softens the equations of state, lowers the maximum neutron star mass, and affects the transport properties of dense matter. The parameter space is constrained for dibaryons by requiring that a 1.44 solar mass neutron star be gravitationally stable.

  2. Symbiotic Stars in X-rays

    NASA Technical Reports Server (NTRS)

    Luna, G. J. M.; Sokoloski, J. L.; Mukai, K.; Nelson, T.

    2014-01-01

    Until recently, symbiotic binary systems in which a white dwarf accretes from a red giant were thought to be mainly a soft X-ray population. Here we describe the detection with the X-ray Telescope (XRT) on the Swift satellite of 9 white dwarf symbiotics that were not previously known to be X-ray sources and one that was previously detected as a supersoft X-ray source. The 9 new X-ray detections were the result of a survey of 41 symbiotic stars, and they increase the number of symbiotic stars known to be X-ray sources by approximately 30%. Swift/XRT detected all of the new X-ray sources at energies greater than 2 keV. Their X-ray spectra are consistent with thermal emission and fall naturally into three distinct groups. The first group contains those sources with a single, highly absorbed hard component, which we identify as probably coming from an accretion-disk boundary layer. The second group is composed of those sources with a single, soft X-ray spectral component, which likely arises in a region where low-velocity shocks produce X-ray emission, i.e. a colliding-wind region. The third group consists of those sources with both hard and soft X-ray spectral components. We also find that unlike in the optical, where rapid, stochastic brightness variations from the accretion disk typically are not seen, detectable UV flickering is a common property of symbiotic stars. Supporting our physical interpretation of the two X-ray spectral components, simultaneous Swift UV photometry shows that symbiotic stars with harder X-ray emission tend to have stronger UV flickering, which is usually associated with accretion through a disk. To place these new observations in the context of previous work on X-ray emission from symbiotic stars, we modified and extended the alpha/beta/gamma classification scheme for symbiotic-star X-ray spectra that was introduced by Muerset et al. based upon observations with the ROSAT satellite, to include a new sigma classification for sources with

  3. Direct observations of sigma phase growth and dissolution in 2205 duplex stainless steel

    SciTech Connect

    Palmer, T.A.; Elmer, J.W.; Babu, S.S.; Specht, E.D.

    2007-10-10

    The formation and growth of sigma ({sigma}) phase in a 2205 duplex stainless steel is monitored during an 850 C isothermal heat treatment using an in situ synchrotron x-ray diffraction technique. At this temperature, {sigma} phase is first observed within approximately 40 seconds of the start of the isothermal heat treatment and grows rapidly over the course of the 3600 second heat treatment to a volume fraction of approximately 13%. A simultaneous increase in the austenite ({gamma}) volume fraction and a decrease in the ferrite ({delta}) volume fraction are observed. The {sigma} phase formed at this temperature is rapidly dissolved within approximately 200 seconds when the temperature is increased to 1000 C. Accompanying this rapid dissolution of the {sigma} phase, the {delta} and {gamma} volume fractions both approach the balanced (50/50) level observed in the as-received material.

  4. Isospin Decomposition of the Photoproduced Sigma pi System Near the Lambda(1405)

    SciTech Connect

    Schumacher, Reinhard A.; Moriya, Kei

    2013-09-01

    Recent experimental results for the reaction \\gamma + p \\to K^+ + \\Sigma + \\pi\\ from CLAS at Jefferson Lab are discussed. It was found that the mass distributions or "line shapes" of the three charge combinations \\Sigma^+ \\pi^-, \\Sigma^0 \\pi^0 and \\Sigma^- \\pi^+ differ significantly. Our results show that the \\Lambda(1405), as the I=0 constituent of the reaction, must be accompanied by an I > 0 component. We discuss phenomenological fits to the data to test the possible forms and magnitudes of these amplitudes. A two-amplitude I=0 fit of Breit-Wigner form to the \\Sigma^0\\pi^0 channel alone works quite well. The addition of a single I=1 amplitude works fairly well to model all the line shapes simultaneously.

  5. Direct Observations of Sigma Phase Growth and Dissolution in 2205 Duplex Stainless Steel

    SciTech Connect

    Palmer, T; Elmer, J; Babu, S; Specht, E

    2005-06-14

    The formation and growth of sigma ({sigma}) phase in a 2205 duplex stainless steel is monitored during an 850 C isothermal heat treatment using an in situ synchrotron x-ray diffraction technique. At this temperature, {sigma} phase is first observed within approximately 40 seconds of the start of the isothermal heat treatment and grows rapidly over the course of the 3600 second heat treatment to a volume fraction of approximately 13%. A simultaneous increase in the austenite ({gamma}) volume fraction and a decrease in the ferrite ({delta}) volume fraction are observed. The {sigma} phase formed at this temperature is rapidly dissolved within approximately 200 seconds when the temperature is increased to 1000 C. Accompanying this rapid dissolution of the {sigma} phase, the {delta} and {gamma} volume fractions both approach the balanced (50/50) level observed in the as-received material.

  6. Quenching of A 2Sigma(+) OH at 300 K by several colliders

    NASA Technical Reports Server (NTRS)

    Wysong, Ingrid J.; Jeffries, Jay B.; Crosley, David R.

    1990-01-01

    Quenching cross sections, sigma(Q), were measured for A 2Sigma(+) OH for a variety of colliders, using the pressure dependence of time-resolved laser-induced fluorescence to obtain quenching cross sections. The OH radicals, produced in a discharge or by photolysis, were maintained in the excited state at 300 K by an Ar buffer bath. It was found that quenching by CF4 and C2F6 the cross sections are very small. For Kr and Ze, the sigma(Q) values were found to be 8 and 27 sq A, respectively. For O2, sigma(Q) was 18 sq A, and for H2O, sigma(Q) was 80 sq A.

  7. Electromagnetic Decay of the $\\Sigma^{0}(1385)$ to $\\Lambda\\gamma$

    SciTech Connect

    Keller, Dustin; Adhikari, Krishna; Adikaram-Mudiyanselage, Dasuni; Aghasyan, Mher; Amaryan, Moscov; Baghdasaryan, Hovhannes; Ball, J P; Ball, Jacques; Battaglieri, Marco; Batourine, V; Bedlinskiy, Ivan; Bennett, Robert; Biselli, Angela; Branford, Derek; Briscoe, Wilbert; Brooks, William; Burkert, Volker; Careccia, Sharon; Carman, Daniel; Casey, Liam; Cole, Philip; Contalbrigo, Marco; Crede, Volker; D'Angelo, Annalisa; Daniel, AJI; Dashyan, Natalya; De Vita, Raffaella; De Sanctis, Enzo; Deur, Alexandre; Dey, Biplap; Dickson, Richard; Djalali, Chaden; Doughty, David; Dupre, Raphael; Egiyan, Hovanes; El Alaoui, Ahmed; Elfassi, Lamiaa; Eugenio, Paul; Fedotov, Gleb; Fegan, Stuart; Forest, Tony; Gabrielyan, Marianna; Gavalian, Gagik; Gevorgyan, Nerses; Giovanetti, Kevin; Girod, Francois-Xavier; Gohn, Wesley; Golovach, Evgeny; Gothe, Ralf; Graham, Lewis; Guidal, Michel; Guegan, Baptiste; Hafidi, Kawtar; Hakobyan, Hayk; Hanretty, Charles; Holtrop, Maurik; Ilieva, Yordanka; Ireland, David; Isupov, Evgeny; Jawalkar, Sucheta; Jenkins, David; Jo, Hyon-Suk; Joo, Kyungseon; Khandaker, Mahbubul; Khetarpal, Puneet; Kim, Andrey; Kim, Wooyoung; Klein, Andreas; Klein, Franz; Konczykowski, Piotr; Kubarovsky, Valery; Kuleshov, Sergey; Kuznetsov, Viacheslav; Lu, Haiyun; MacGregor, Ian; Markov, Nikolai; McAndrew, Josephine; KcKinnon, Bryan; Meyer, Curtis; Micherdzinska, Anna; Mirazita, Marco; Mokeev, Viktor; Moreno, Brahim; Moriya, Kei; Morrison, Brian; Moutarde, Herve; Munevar Espitia, Edwin; Nadel-Turonski, Pawel; Ni, Andrey; Niccolai, Silvia; Niculescu, Gabriel; Niculescu, Maria-Ioana; Osipenko, Mikhail; Ostrovidov, Alexander; Paremuzyan, Rafayel; Park, Kijun; Park, Sungkyun; Pasyuk, Eugene; Pasyuk, Evgueni; Pereira, Sergio; Pappalardo, Luciano; Pisano, Silvia; Pogorelko, Oleg; Pozdnyakov, Sergey; Price, John; Procureur, Sebastien; Protopopescu, Dan; Raue, Brian; Ripani, Marco; Ritchie, Barry; Rosner, Guenther; Rossi, Patrizia; Sabatie, Franck; Saini, Mukesh; Salgado, Carlos; Schott, Diane; Schumacher, Reinhard; Seder, Erin; Seraydaryan, Heghine; Sharabian, Youri; Smith, Elton; Smith, Gregory; Sober, Daniel; Stepanyan, Stepan; Stoler, Paul; Strakovski, Igor; Strauch, Steffen; Taiuti, Mauro; Tang, Wei; Taylor, Charles; Vernarsky, Brian; Vineyard, Michael; Voutier, Eric; Weinstein, Lawrence; Watts, Daniel; Wood, Michael; Zachariou, Nicholas; Zana, Lorenzo; Zhao, Bo; Zhao, Zhiwen

    2011-04-01

    The electromagnetic decay $\\Sigma^0(1385) \\to \\Lambda \\gamma$ was studied using the CLAS detector at the Thomas Jefferson National Accelerator Facility. A real photon beam with a maximum energy of 3.8 GeV was incident on a proton target, producing an exclusive final state of $K^+\\Sigma^{*0}$. We report the decay widths ratio $\\Sigma^0(1385) \\to \\Lambda\\gamma$/ $\\Sigma^0(1385) \\to \\Lambda\\pi^0$ = $1.42 \\pm 0.12(\\text{stat})_{-0.07}^{+0.11}(\\text{sys})$%. This ratio is larger than most theoretical predictions by factors ranging from 1.5-3, but is consistent with the only other experimental measurement. From the reported ratio we calculate the partial width and electromagnetic transition magnetic moment for $\\Sigma^0(1385) \\to \\Lambda\\gamma$.

  8. America's Star Libraries

    ERIC Educational Resources Information Center

    Lyons, Ray; Lance, Keith Curry

    2009-01-01

    "Library Journal"'s new national rating of public libraries, the "LJ" Index of Public Library Service, identifies 256 "star" libraries. It rates 7,115 public libraries. The top libraries in each group get five, four, or three Michelin guide-like stars. All included libraries, stars or not, can use their scores to learn from their peers and improve…

  9. Managing the star performer.

    PubMed

    Hills, Laura

    2013-01-01

    Our culture seems to be endlessly fascinated with its stars in entertainment, athletics, politics, and business, and holds fast to the idea that extraordinary talent accounts for an individual's extraordinary performance. At first glance, managing a star performer in your medical practice may seem like it would be an easy task. However, there's much more to managing a star performer than many practice managers realize. The concern is how to keep the star performer happy and functioning at a high level without detriment to the rest of the medical practice team. This article offers tips for practice managers who manage star performers. It explores ways to keep the star performer motivated, while at the same time helping the star performer to meld into the existing medical practice team. This article suggests strategies for redefining the star performer's role, for holding the star performer accountable for his or her behavior, and for coaching the star performer. Finally, this article offers practical tips for keeping the star performer during trying times, for identifying and cultivating new star performers, and for managing medical practice prima donnas. PMID:23767124

  10. A Search for Planetary Transits of the Star HD 187123 by Spot Filter CCD Differential Photometry

    NASA Technical Reports Server (NTRS)

    Castellano, T.; DeVincenzi, D. (Technical Monitor)

    2000-01-01

    A novel method for performing high precision, time series CCD differential photometry of bright stars using a spot filter, is demonstrated. Results for several nights of observing of the 51 Pegasi b-type planet bearing star HD 187123 are presented. Photometric precision of 0.0015 - 0.0023 magnitudes is achieved. No transits are observed at the epochs predicted from the radial velocity observation. If the planet orbiting HD 187123 at 0.0415 AU is an inflated Jupiter similar in radius to HD 209458b it would have been detected at the greater than 6(sigma), level if the orbital inclination is near 90 degrees and at the greater than 3(sigma), level if the orbital inclination is as small as 82.7 degrees.

  11. A method to detect p-mode oscillations in solar-like star signals

    NASA Astrophysics Data System (ADS)

    Régulo, C.; Roca Cortés, T.

    2002-12-01

    A good example of finding a signal buried in noise, a common problem in Astrophysics, is the search for stellar oscillations in the acoustic power spectrum of solar-like stars. In this work it is shown that it is possible to find this type of signal in the power spectrum of stellar oscillations if the peaks are ``almost'' equally spaced in frequency, as the asymptotic theory for acoustic modes predicts. This signature of the power spectra of the p-mode oscillations in solar-like stars is used to design a method that allows the identification of the signal even when this signal is completely buried in noise, sigma_signal /sigma_signal +noise < 1/25.

  12. SIM PlanetQuest Key Project Precursor Observations to Detect Gas Giant Planets Around Young Stars

    NASA Technical Reports Server (NTRS)

    Tanner, Angelle; Beichman, Charles; Akeson, Rachel; Ghez, Andrea; Grankin, Konstantin N.; Herbst, William; Hillenbrand, Lynne; Huerta, Marcos; Konopacky, Quinn; Metchev, Stanimir; Mohanty, Subhanjoy; Prato, L.; Simon, Michal

    2008-01-01

    We present a review of precursor observing programs for the SIM PlanetQuest Key project devoted to detecting Jupiter mass planets around young stars. In order to ensure that the stars in the sample are free of various sources of astrometric noise that might impede the detection of planets, we have initiated programs to collect photometry, high contrast images, interferometric data and radial velocities for stars in both the Northern and Southern hemispheres. We have completed a high contrast imaging survey of target stars in Taurus and the Pleiades and found no definitive common proper motion companions within one arcsecond (140 AU) of the SIM targets. Our radial velocity surveys have shown that many of the target stars in Sco-Cen are fast rotators and a few stars in Taurus and the Pleiades may have sub-stellar companions. Interferometric data of a few stars in Taurus show no signs of stellar or sub-stellar companions with separations of <5 mas. The photometric survey suggests that approximately half of the stars initially selected for this program are variable to a degree (1(sigma) >0.1 mag) that would degrade the astrometric accuracy achievable for that star. While the precursor programs are still a work in progress, we provide a comprehensive list of all targets ranked according to their viability as a result of the observations taken to date. By far, the observable that removes the most targets from the SIM-YSO program is photometric variability.

  13. THE OBSERVED M-{sigma} RELATIONS IMPLY THAT SUPER-MASSIVE BLACK HOLES GROW BY COLD CHAOTIC ACCRETION

    SciTech Connect

    Nayakshin, Sergei; King, Andrew R.; Power, Chris

    2012-07-01

    We argue that current observations of M-{sigma} relations for galaxies can be used to constrain theories of super-massive black holes (SMBHs) feeding. In particular, assuming that SMBH mass is limited only by the feedback on the gas that feeds it, we show that SMBHs fed via a planar galaxy-scale gas flow, such as a disk or a bar, should be much more massive than their counterparts fed by quasi-spherical inflows. This follows from the relative inefficiency of active galactic nucleus feedback on a flattened inflow. We find that even under the most optimistic conditions for SMBH feedback on flattened inflows, the mass at which the SMBH expels the gas disk and terminates its own growth is a factor of several higher than the one established for quasi-spherical inflows. Any beaming of feedback away from the disk and any disk self-shadowing strengthen this result further. Contrary to this theoretical expectation, recent observations have shown that SMBHs in pseudobulge galaxies (which are associated with barred galaxies) are typically under- rather than overmassive when compared with their classical bulge counterparts at a fixed value of {sigma}. We conclude from this that SMBHs are not fed by large (100 pc to many kpc) scale gas disks or bars, most likely because such planar flows are turned into stars too efficiently to allow any SMBH growth. Based on this and other related observational evidence, we argue that most SMBHs grow by chaotic accretion of gas clouds with a small and nearly randomly distributed direction of angular momentum.

  14. Deconfinement to quark matter in neutron stars - The influence of strong magnetic fields

    SciTech Connect

    Dexheimer, V.; Negreiros, R.; Schramm, S.; Hempel, M.

    2013-03-25

    We use an extended version of the hadronic SU(3) non-linear realization of the sigma model that also includes quarks to study hybrid stars. Within this approach, the degrees of freedom change naturally as the temperature/density increases. Different prescriptions of charge neutrality, local and global, are tested and the influence of strong magnetic fields and the anomalous magnetic moment on the particle population is discussed.

  15. Ponderable soliton stars

    NASA Technical Reports Server (NTRS)

    Chiu, Hong-Yee

    1990-01-01

    The theory of Lee and Pang (1987), who obtained solutions for soliton stars composed of zero-temperature fermions and bosons, is applied here to quark soliton stars. Model soliton stars based on a simple physical model of the proton are computed, and the properties of the solitons are discussed, including the important problem of the existence of a limiting mass and thus the possible formation of black holes of primordial origin. It is shown that there is a definite mass limit for ponderable soliton stars, so that during cooling a soliton star might reach a stage beyond which no equilibrium configuration exists and the soliton star probably will collapse to become a black hole. The radiation of ponderable soliton stars may alter the short-wavelength character of the cosmic background radiation, and may be observed as highly redshifted objects at z of about 100,000.

  16. Star field simulator

    NASA Technical Reports Server (NTRS)

    1985-01-01

    A Star Field Simulator has been developed to serve as a source of radiation for the ASTRO Star Tracker. The star tracker and simulator are components of a motion compensation test facility located at Marshall Space Flight Center in Huntsville, Alabama. Preflight tests and simulations using various levels of guide stars are performed in the test facility to establish performance of the motion compensation system before being used in a flight environment. The ASTRO Star Tracker operates over a wide dynamic range of irradiance corresponding to visual stellar magnitudes of -0.8 to 8. A minimum of three simulated guide stars with variable magnitudes are needed to fully test the Star Tracker performance under simulated mission conditions.

  17. Starspot evolution, differential rotation, and magnetic cycles in the chromospherically active binaries lambda andromedae, sigma Geminorum, II Pegasi, and V711 Tauri

    NASA Technical Reports Server (NTRS)

    Henry, Gregory W.; Eaton, Joel A.; Hamer, Jamesia; Hall, Douglas S.

    1995-01-01

    We have analyzed 15-19 yr of photoelectric photometry, obtained manually and with automated telescopes, of the chromospherically active binaries lambda And, sigma Gem, II Peg, and V711 Tau. These observations let us identify individual dark starspots on the stellar surfaces from periodic dimming of the starlight, follow the evolution of these spots, and search for long-term cyclic changes in the properties of these starspots that might reveal magnetic cycles analogous to the Sun's 11 yr sunspot cycle. We developed a computer code to fit a simple two-spot model to our observed light curves that allows us to extract the most easily determinable and most reliable spot parameters from the light curves, i.e., spot longitudes and radii. We then used these measured properties to identify individual spots and to chart their life histories by constructing migration and amplitude curves. We identified and followed 11 spots in lambda And, 16 in sigma Gem, 12 in II Peg, and 15 in V711 Tau. Lifetimes of individual spots ranged from a few months to longer than 6 yr. Differential rotation coefficients, estimated from the observed range of spot rotation periods for each star and defined by equation (2), were 0.04 for lambda And, 0.038 for sigma Gem, 0.005 for II Peg, and 0.006 for V711 Tau, versus 0.19 for the Sun. We searched for cyclic changes in mean brightness, B-V color index, and spot rotation period as evidence for long-term cycles. Of these, long-term variability in mean brightness appears to offer the best evidence for such cycles in these four stars. Cycles of 11.1 yr for lambda And, 8.5 yr for sigma Gem, 11 yr for II Peg, and 16 yr V711 Tau are implied by these mean brightness changes. Cyclic changes in spot rotation period were found in lambda And and possibly II Peg. Errors in B-V were too large for any long-term changes to be detectable.

  18. NEUTRON STARS WITH SMALL RADII-THE ROLE OF {Delta} RESONANCES

    SciTech Connect

    Schuerhoff, Torsten; Schramm, Stefan; Dexheimer, Veronica

    2010-11-20

    Recent neutron star observations suggest that the masses and radii of neutron stars may be smaller than previously considered, which would disfavor a purely nucleonic equation of state (EoS). In our model, we use a flavor SU(3) sigma model that includes {Delta} resonances and hyperons in the EoS. We find that if the coupling of the {Delta} resonances to the vector mesons is slightly smaller than that of the nucleons, we can reproduce both the measured mass-radius relationship and the extrapolated EoS.

  19. Topography of Slow Sigma Power during Sleep is Associated with Processing Speed in Preschool Children

    PubMed Central

    Doucette, Margaret R.; Kurth, Salome; Chevalier, Nicolas; Munakata, Yuko; LeBourgeois, Monique K.

    2015-01-01

    Cognitive development is influenced by maturational changes in processing speed, a construct reflecting the rapidity of executing cognitive operations. Although cognitive ability and processing speed are linked to spindles and sigma power in the sleep electroencephalogram (EEG), little is known about such associations in early childhood, a time of major neuronal refinement. We calculated EEG power for slow (10–13 Hz) and fast (13.25–17 Hz) sigma power from all-night high-density electroencephalography (EEG) in a cross-sectional sample of healthy preschool children (n = 10, 4.3 ± 1.0 years). Processing speed was assessed as simple reaction time. On average, reaction time was 1409 ± 251 ms; slow sigma power was 4.0 ± 1.5 μV2; and fast sigma power was 0.9 ± 0.2 μV2. Both slow and fast sigma power predominated over central areas. Only slow sigma power was correlated with processing speed in a large parietal electrode cluster (p < 0.05, r ranging from −0.6 to −0.8), such that greater power predicted faster reaction time. Our findings indicate regional correlates between sigma power and processing speed that are specific to early childhood and provide novel insights into the neurobiological features of the EEG that may underlie developing cognitive abilities. PMID:26556377

  20. Sigma: Strain-level inference of genomes from metagenomic analysis for biosurveillance

    DOE PAGESBeta

    Ahn, Tae-Hyuk; Chai, Juanjuan; Pan, Chongle

    2014-09-29

    Motivation: Metagenomic sequencing of clinical samples provides a promising technique for direct pathogen detection and characterization in biosurveillance. Taxonomic analysis at the strain level can be used to resolve serotypes of a pathogen in biosurveillance. Sigma was developed for strain-level identification and quantification of pathogens using their reference genomes based on metagenomic analysis. Results: Sigma provides not only accurate strain-level inferences, but also three unique capabilities: (i) Sigma quantifies the statistical uncertainty of its inferences, which includes hypothesis testing of identified genomes and confidence interval estimation of their relative abundances; (ii) Sigma enables strain variant calling by assigning metagenomic readsmore » to their most likely reference genomes; and (iii) Sigma supports parallel computing for fast analysis of large datasets. In conclusion, the algorithm performance was evaluated using simulated mock communities and fecal samples with spike-in pathogen strains. Availability and Implementation: Sigma was implemented in C++ with source codes and binaries freely available at http://sigma.omicsbio.org.« less

  1. Kinetic Study to Predict Sigma Phase Formation in Duplex Stainless Steels

    NASA Astrophysics Data System (ADS)

    dos Santos, Daniella Caluscio; Magnabosco, Rodrigo

    2016-04-01

    This work presents an improved kinetic study of sigma phase formation during isothermal aging between 973 K and 1223 K (700 °C and 950 °C), based on Kolmogorov-Johnson-Mehl-Avrami (K-J-M-A) model, established from volume fraction of sigma phase determined in backscattered electron images over polished surfaces of aged samples. The kinetic study shows a change in the main mechanism of sigma formation between 973 K and 1173 K (700 °C and 900 °C), from a nucleation-governed stage to a diffusion-controlled growth-coarsening stage, confirmed by a double inclination in K-J-M-A plots and microstructural observations. A single inclination in K-J-M-A plots was observed for the 1223 K (950 °C) aging temperature, showing that kinetic behavior in this temperature is only related to diffusion-controlled growth of sigma phase. The estimated activation energies for the nucleation of sigma phase are close to the molybdenum diffusion in ferrite, probably the controlling mechanism of sigma phase nucleation. The proposed time-temperature-transformation (TTT) diagram shows a "double c curve" configuration, probably associated to the presence of chi-phase formed between 973 K and 1073 K (700 °C and 800 °C), which acts as heterogeneous nuclei for sigma phase formation in low aging temperatures.

  2. Topography of Slow Sigma Power during Sleep is Associated with Processing Speed in Preschool Children.

    PubMed

    Doucette, Margaret R; Kurth, Salome; Chevalier, Nicolas; Munakata, Yuko; LeBourgeois, Monique K

    2015-11-04

    Cognitive development is influenced by maturational changes in processing speed, a construct reflecting the rapidity of executing cognitive operations. Although cognitive ability and processing speed are linked to spindles and sigma power in the sleep electroencephalogram (EEG), little is known about such associations in early childhood, a time of major neuronal refinement. We calculated EEG power for slow (10-13 Hz) and fast (13.25-17 Hz) sigma power from all-night high-density electroencephalography (EEG) in a cross-sectional sample of healthy preschool children (n = 10, 4.3 ± 1.0 years). Processing speed was assessed as simple reaction time. On average, reaction time was 1409 ± 251 ms; slow sigma power was 4.0 ± 1.5 μV²; and fast sigma power was 0.9 ± 0.2 μV². Both slow and fast sigma power predominated over central areas. Only slow sigma power was correlated with processing speed in a large parietal electrode cluster (p < 0.05, r ranging from -0.6 to -0.8), such that greater power predicted faster reaction time. Our findings indicate regional correlates between sigma power and processing speed that are specific to early childhood and provide novel insights into the neurobiological features of the EEG that may underlie developing cognitive abilities.

  3. Topography of Slow Sigma Power during Sleep is Associated with Processing Speed in Preschool Children.

    PubMed

    Doucette, Margaret R; Kurth, Salome; Chevalier, Nicolas; Munakata, Yuko; LeBourgeois, Monique K

    2015-01-01

    Cognitive development is influenced by maturational changes in processing speed, a construct reflecting the rapidity of executing cognitive operations. Although cognitive ability and processing speed are linked to spindles and sigma power in the sleep electroencephalogram (EEG), little is known about such associations in early childhood, a time of major neuronal refinement. We calculated EEG power for slow (10-13 Hz) and fast (13.25-17 Hz) sigma power from all-night high-density electroencephalography (EEG) in a cross-sectional sample of healthy preschool children (n = 10, 4.3 ± 1.0 years). Processing speed was assessed as simple reaction time. On average, reaction time was 1409 ± 251 ms; slow sigma power was 4.0 ± 1.5 μV²; and fast sigma power was 0.9 ± 0.2 μV². Both slow and fast sigma power predominated over central areas. Only slow sigma power was correlated with processing speed in a large parietal electrode cluster (p < 0.05, r ranging from -0.6 to -0.8), such that greater power predicted faster reaction time. Our findings indicate regional correlates between sigma power and processing speed that are specific to early childhood and provide novel insights into the neurobiological features of the EEG that may underlie developing cognitive abilities. PMID:26556377

  4. Dominant lethal phenotype of a mutation in the -35 recognition region of Escherichia coli sigma 70.

    PubMed Central

    Keener, J; Nomura, M

    1993-01-01

    A dominant lethal mutation in the Escherichia coli rpoD gene, which encodes sigma 70, the promoter recognition subunit of RNA polymerase, was isolated after random mutagenesis. The lethal gene was maintained under control of the lac repressor on a low copy plasmid. An amount of lethal sigma 70 that was nearly equimolar with the chromosomally encoded sigma 70 was sufficient to cause cessation of growth. RNA synthesis per unit cell mass was unaffected, but protein synthesis was inhibited by the mutant sigma 70. The amino acid change (Glu-585 to Gln) was in a region of sigma 70 thought to bind the -35 hexamer of the promoter, and the mutant sigma 70 caused increased expression from promoters with nonconsensus bases in the third position of the -35 hexamer. A null mutation of the fis gene could partially suppress the mutant phenotype. These properties are consistent with those expected of a sigma 70 insensitive to growth rate control of rRNA and tRNA promoters. Images Fig. 2 PMID:7680477

  5. Density-Dependent Relations among Properties of Hadronic Matter and Applications to Hadron-Quark Stars

    SciTech Connect

    Uechi, Hiroshi; Uechi, Schun T.

    2011-05-06

    Density-dependent relations among the saturation properties of symmetric nuclear matter and hyperonic matter, and properties of hadron-(strange) quark stars are shown by applying the conserving nonlinear {sigma}-{omega}-{rho} hadronic mean-field theory. Nonlinear interactions are renormalized self-consistently as effective coupling constants, effective masses, and sources of equations of motion by maintaining thermodynamic consistency to the mean-field approximation. Effective masses and coupling constants at the saturation point of symmetric nuclear matter simultaneously determine the binding energy and saturation properties of hyperonic matter. The coupling constants expected from the hadronic mean-field model and SU(6) quark model for the vector coupling constants are compared by calculating masses of hadron-quark neutron stars. The nonlinear {sigma}-{omega}-{rho} mean-field approximation with vacuum fluctuation corrections and strange quark matter defined by the MIT-bag model were employed to examine properties of hadron-(strange) quark stars. We found that hadron-(strange) quark stars become more stable at high densities compared to pure hadronic and strange quark stars.

  6. GRAVITATIONAL CONUNDRUM? DYNAMICAL MASS SEGREGATION VERSUS DISRUPTION OF BINARY STARS IN DENSE STELLAR SYSTEMS

    SciTech Connect

    De Grijs, Richard; Li, Chengyuan; Zheng, Yong; Kouwenhoven, M. B. N.; Deng, Licai; Hu, Yi; Wicker, James E.

    2013-03-01

    Upon their formation, dynamically cool (collapsing) star clusters will, within only a few million years, achieve stellar mass segregation for stars down to a few solar masses, simply because of gravitational two-body encounters. Since binary systems are, on average, more massive than single stars, one would expect them to also rapidly mass segregate dynamically. Contrary to these expectations and based on high-resolution Hubble Space Telescope observations, we show that the compact, 15-30 Myr old Large Magellanic Cloud cluster NGC 1818 exhibits tantalizing hints at the {approx}> 2{sigma} level of significance (>3{sigma} if we assume a power-law secondary-to-primary mass-ratio distribution) of an increasing fraction of F-star binary systems (with combined masses of 1.3-1.6 M {sub Sun }) with increasing distance from the cluster center, specifically between the inner 10''-20'' (approximately equivalent to the cluster's core and half-mass radii) and the outer 60''-80''. If confirmed, then this will offer support for the theoretically predicted but thus far unobserved dynamical disruption processes of the significant population of 'soft' binary systems-with relatively low binding energies compared to the kinetic energy of their stellar members-in star clusters, which we have access to here by virtue of the cluster's unique combination of youth and high stellar density.

  7. Prediction of three sigma maximum dispersed density for aerospace applications

    NASA Technical Reports Server (NTRS)

    Charles, Terri L.; Nitschke, Michael D.

    1993-01-01

    Free molecular heating (FMH) is caused by the transfer of energy during collisions between the upper atmosphere molecules and a space vehicle. The dispersed free molecular heating on a surface is an important constraint for space vehicle thermal analyses since it can be a significant source of heating. To reduce FMH to a spacecraft, the parking orbit is often designed to a higher altitude at the expense of payload capability. Dispersed FMH is a function of both space vehicle velocity and atmospheric density, however, the space vehicle velocity variations are insignificant when compared to the atmospheric density variations. The density of the upper atmosphere molecules is a function of altitude, but also varies with other environmental factors, such as solar activity, geomagnetic activity, location, and time. A method has been developed to predict three sigma maximum dispersed density for up to 15 years into the future. This method uses a state-of-the-art atmospheric density code, MSIS 86, along with 50 years of solar data, NASA and NOAA solar activity predictions for the next 15 years, and an Aerospace Corporation correlation to account for density code inaccuracies to generate dispersed maximum density ratios denoted as 'K-factors'. The calculated K-factors can be used on a mission unique basis to calculate dispersed density, and hence dispersed free molecular heating rates. These more accurate K-factors can allow lower parking orbit altitudes, resulting in increased payload capability.

  8. A High Performance Delta-Sigma Modulator for Neurosensing.

    PubMed

    Xu, Jian; Zhao, Menglian; Wu, Xiaobo; Islam, Md Kafiul; Yang, Zhi

    2015-01-01

    Recorded neural data are frequently corrupted by large amplitude artifacts that are triggered by a variety of sources, such as subject movements, organ motions, electromagnetic interferences and discharges at the electrode surface. To prevent the system from saturating and the electronics from malfunctioning due to these large artifacts, a wide dynamic range for data acquisition is demanded, which is quite challenging to achieve and would require excessive circuit area and power for implementation. In this paper, we present a high performance Delta-Sigma modulator along with several design techniques and enabling blocks to reduce circuit area and power. The modulator was fabricated in a 0.18-µm CMOS process. Powered by a 1.0-V supply, the chip can achieve an 85-dB peak signal-to-noise-and-distortion ratio (SNDR) and an 87-dB dynamic range when integrated over a 10-kHz bandwidth. The total power consumption of the modulator is 13 µW, which corresponds to a figure-of-merit (FOM) of 45 fJ/conversion step. These competitive circuit specifications make this design a good candidate for building high precision neurosensors. PMID:26262623

  9. Amplitude relations in non-linear sigma model

    NASA Astrophysics Data System (ADS)

    Chen, Gang; Du, Yi-Jian

    2014-01-01

    In this paper, we investigate tree-level scattering amplitude relations in U( N) non-linear sigma model. We use Cayley parametrization. As was shown in the recent works [23,24], both on-shell amplitudes and off-shell currents with odd points have to vanish under Cayley parametrization. We prove the off-shell U(1) identity and fundamental BCJ relation for even-point currents. By taking the on-shell limits of the off-shell relations, we show that the color-ordered tree amplitudes with even points satisfy U(1)-decoupling identity and fundamental BCJ relation, which have the same formations within Yang-Mills theory. We further state that all the on-shell general KK, BCJ relations as well as the minimal-basis expansion are also satisfied by color-ordered tree amplitudes. As a consequence of the relations among color-ordered amplitudes, the total 2 m-point tree amplitudes satisfy DDM form of color decomposition as well as KLT relation.

  10. A High Performance Delta-Sigma Modulator for Neurosensing

    PubMed Central

    Xu, Jian; Zhao, Menglian; Wu, Xiaobo; Islam, Md. Kafiul; Yang, Zhi

    2015-01-01

    Recorded neural data are frequently corrupted by large amplitude artifacts that are triggered by a variety of sources, such as subject movements, organ motions, electromagnetic interferences and discharges at the electrode surface. To prevent the system from saturating and the electronics from malfunctioning due to these large artifacts, a wide dynamic range for data acquisition is demanded, which is quite challenging to achieve and would require excessive circuit area and power for implementation. In this paper, we present a high performance Delta-Sigma modulator along with several design techniques and enabling blocks to reduce circuit area and power. The modulator was fabricated in a 0.18-μm CMOS process. Powered by a 1.0-V supply, the chip can achieve an 85-dB peak signal-to-noise-and-distortion ratio (SNDR) and an 87-dB dynamic range when integrated over a 10-kHz bandwidth. The total power consumption of the modulator is 13 μW, which corresponds to a figure-of-merit (FOM) of 45 fJ/conversion step. These competitive circuit specifications make this design a good candidate for building high precision neurosensors. PMID:26262623

  11. Optimizing The DSSC Fabrication Process Using Lean Six Sigma

    NASA Astrophysics Data System (ADS)

    Fauss, Brian

    Alternative energy technologies must become more cost effective to achieve grid parity with fossil fuels. Dye sensitized solar cells (DSSCs) are an innovative third generation photovoltaic technology, which is demonstrating tremendous potential to become a revolutionary technology due to recent breakthroughs in cost of fabrication. The study here focused on quality improvement measures undertaken to improve fabrication of DSSCs and enhance process efficiency and effectiveness. Several quality improvement methods were implemented to optimize the seven step individual DSSC fabrication processes. Lean Manufacturing's 5S method successfully increased efficiency in all of the processes. Six Sigma's DMAIC methodology was used to identify and eliminate each of the root causes of defects in the critical titanium dioxide deposition process. These optimizations resulted with the following significant improvements in the production process: 1. fabrication time of the DSSCs was reduced by 54 %; 2. fabrication procedures were improved to the extent that all critical defects in the process were eliminated; 3. the quantity of functioning DSSCs fabricated was increased from 17 % to 90 %.

  12. Supersymmetric sigma model of disordered, isotropic, elastic media

    NASA Astrophysics Data System (ADS)

    Photiadis, Douglas

    The supersymmetry method proposed by Efetov in 1983 has been enormously successful at describing a broad range of phenomena involving disorder, providing a framework for understanding and going beyond the successes of random matrix theory and allowing a calculation of the slowing of diffusion as the Anderson transition is approached. The original model described the propagation of a scalar wave in a disordered medium, and subsequent work extended these ideas to classical waves, optical or elastic, with the approximation that the wave propagation can be similarly described by a scalar theory. Such a theory cannot however account correctly for scattering between different polarizations. A direct attempt to derive a supersymmetric model describing elastic waves results in a non-renormalizable field theory, and poses substantial difficulties. We have obtained a supersymmetric sigma model by considering the dual model which describes a generalized superstress field. The model enables one to fully account for the different wave types and polarizations in the medium. We will present our recent results in this area, including model predictions for the obtained diffusion constants, and the effects of renormalization to first order. This research was funded by the Office of Naval Research.

  13. Beyond the standard gauging: gauge symmetries of Dirac sigma models

    NASA Astrophysics Data System (ADS)

    Chatzistavrakidis, Athanasios; Deser, Andreas; Jonke, Larisa; Strobl, Thomas

    2016-08-01

    In this paper we study the general conditions that have to be met for a gauged extension of a two-dimensional bosonic σ-model to exist. In an inversion of the usual approach of identifying a global symmetry and then promoting it to a local one, we focus directly on the gauge symmetries of the theory. This allows for action functionals which are gauge invariant for rather general background fields in the sense that their invariance conditions are milder than the usual case. In particular, the vector fields that control the gauging need not be Killing. The relaxation of isometry for the background fields is controlled by two connections on a Lie algebroid L in which the gauge fields take values, in a generalization of the common Lie-algebraic picture. Here we show that these connections can always be determined when L is a Dirac structure in the H-twisted Courant algebroid. This also leads us to a derivation of the general form for the gauge symmetries of a wide class of two-dimensional topological field theories called Dirac σ-models, which interpolate between the G/G Wess-Zumino-Witten model and the (Wess-Zumino-term twisted) Poisson sigma model.

  14. Identification of sigma S-regulated genes in Salmonella typhimurium: complementary regulatory interactions between sigma S and cyclic AMP receptor protein.

    PubMed

    Fang, F C; Chen, C Y; Guiney, D G; Xu, Y

    1996-09-01

    sigma S (RpoS)-regulated lacZ transcriptional fusions in Salmonella typhimurium were identified from a MudJ transposon library by placing the rpoS gene under the control of the araBAD promoter and detecting lacZ expression in the presence or absence of arabinose supplementation. Western blot (immunoblot) analysis of bacteria carrying PBAD::rpoS demonstrated arabinose-dependent rpoS expression during all phases of growth. sigma S-dependent gene expression of individual gene fusions was confirmed by P22-mediated transduction of the MudJ insertions into wild-type or rpoS backgrounds. Analysis of six insertions revealed the known sigma S-regulated gene otsA, as well as five novel loci. Each of these genes is maximally expressed in stationary phase, and all but one show evidence of cyclic AMP receptor protein-dependent repression during logarithmic growth which is relieved in stationary phase. For these genes, as well as for the sigma S-regulated spvB plasmid virulence gene, a combination of rpoS overexpression and crp inactivation can result in high-level expression during logarithmic growth. The approach used to identify sigma S-regulated genes in this study provides a general method for the identification of genes controlled by trans-acting regulatory factors.

  15. First Observation of the Cabibbo-suppressed Decays Xi+(c) ---> Sigma+ pi- pi+ and Xi+(c) ---> Sigma- pi+ pi+ and Measurement of their Branching Ratios

    SciTech Connect

    Vazquez-Jauregui, E.; Engelfried, J.; Akgun, U.; Alkhazov, Georgiy; Amaro-Reyes, J.; Atamantchouk, A.G.; Ayan, Ahmet Sedat; Balatz, M.Y.; Blanco-Covarrubias, A.; Bondar, N.F.; Cooper, Peter S.; /Fermilab /Michigan U., Flint

    2008-04-01

    The authors report the first observation of two Cabibbo-suppressed decay modes, {Xi}{sub c}{sup +} {yields} {Sigma}{sup +}{pi}{sup -}{pi}{sup +} and {Xi}{sub c}{sup +} {yields} {Sigma}{sup -} {pi}{sup +}{pi}{sup +}. They observe 56 {+-} 13 over a background of 21, and 23 {+-} 7 over a background of 12 events, respectively, for the signals. The data were accumulated using the SELEX spectrometer during the 1996-1997 fixed target run at Fermilab, chiefly from a 600 GeV/c {Sigma}{sup -} beam. The branching ratios of the decays relative to the Cabibbo-favored {Xi}{sub c}{sup +} {yields} {Xi}{sup -}{pi}{sup +}{pi}{sup +} are measured to be B({Xi}{sub c}{sup +} {yields} {Sigma}{sup +}{pi}{sup -}{pi}{sup +})/B({xi}{sub c}{sup +} {yields} {Xi}{sup -} {pi}{sup +}{pi}{sup +}) = 0.50 {+-} 0.20, and B({Xi}{sub c}{sup +} {yields} {Sigma}{sup -}{pi}{sup +}{pi}{sup +})/B({Xi}{sub c}{sup +} {yields} {Xi}{sup -}{pi}{sup +}{pi}{sup +}) = 0.23 {+-} 0.11, respectively. They also report branching ratios for the same decay modes of the {Lambda}{sub c}{sup +} relative to {Lambda}{sub c}{sup +} {yields} pK{sup -}{pi}{sup +}.

  16. Maturational Patterns of Sigma Frequency Power Across Childhood and Adolescence: A Longitudinal Study

    PubMed Central

    Campbell, Ian G.; Feinberg, Irwin

    2016-01-01

    Study Objectives: To further evaluate adolescent brain maturation by determining the longitudinal trajectories of nonrapid eye movement (NREM) sigma (11–15 Hz) power across childhood-adolescence. Methods: The maturational trend for sigma (11–15 Hz) power was evaluated in an accelerated longitudinal study of three overlapping age cohorts (n = 92) covering ages 6 to 18 y. Semiannually, sleep electroencephalography (EEG) was recorded from participants sleeping at home in their normal sleep environment while keeping their current school night schedules. Results: Sigma frequencies became faster with age. The frequency of the 11–15 Hz spectral peak increased linearly. Sigma frequency power (SFP) declined with age, but its trajectory was complex (cubic). Power in a group of low sigma subfrequencies declined with age. Power in a group of high sigma frequencies increased with age. Power in subfrequencies within 11–15 Hz also showed different trends across the night, with lower frequencies increasing across NREM periods and higher frequencies decreasing across NREM periods. The upper and lower boundaries for the sigma frequencies that changed across NREMPs shifted upward with age. Conclusions: We hypothesize that these maturational brain changes result from synaptic elimination which decreases sleep depth and streamlines circuits. SFP displays a maturational trajectory different from both delta and theta power. Theories on the function of sigma must be reconciled with its maturational trajectory. These findings further demonstrate the value of sleep EEG for studying noninvasively the complex developmental brain changes of adolescence. Citation: Campbell IG, Feinberg I. Maturational patterns of sigma frequency power across childhood and adolescence: a longitudinal study. SLEEP 2016;39(1):193–201. PMID:26285004

  17. Fourier transform microwave spectroscopy of HZnCN(X 1Sigma+) and ZnCN(X 2Sigma+).

    PubMed

    Sun, M; Apponi, A J; Ziurys, L M

    2009-01-21

    The pure rotational spectrum of HZnCN in its X (1)Sigma(+) electronic state has been recorded using pulsed Fourier transform microwave (FTMW) techniques in the frequency range 7-39 GHz-the first spectroscopic study of this species in the gas phase. The FTMW spectrum of ZnCN(X (2)Sigma(+)) has been measured as well. A new FTMW spectrometer with an angled beam and simplified electronics, based on a cryopump, was employed for these experiments. The molecules were created in a dc discharge from a gas mixture of Zn(CH(3))(2) and cyanogen (1% D(2) for the deuterated analogs), diluted with argon, that was expanded supersonically from a pulsed nozzle. Seven isotopologues of HZnCN arising from zinc, deuterium, and (13)C substitutions were studied; for every species, between three and five rotational transitions were recorded, each consisting of numerous hyperfine components arising from nitrogen, and in certain cases, deuterium, and 67-zinc nuclear spins. Four transitions of ZnCN were measured. From these data, rotational, nuclear spin-rotation, and quadrupole coupling constants have been determined for HZnCN, as well as rotational, and magnetic and quadrupole hyperfine parameters for the ZnCN radical. The bond lengths determined for HZnCN are r(H-Zn)=1.495 A, r(Zn-C)=1.897 A, and r(C-N)=1.146 A, while those for ZnCN are r(Zn-C)=1.950 A and r(C-N)=1.142 A. The zinc-carbon bond length thus shortens with the addition of the H atom. The nitrogen quadrupole coupling constant eqQ was found to be virtually identical in both cyanide species (-5.089 and -4.931 MHz), suggesting that the electric field gradient across the N nucleus is not influenced by the H atom. The quadrupole constant for the (67)Zn nucleus in H(67)ZnCN is unusually large relative to that in (67)ZnF (-104.578 versus -60 MHz), evidence that the bonding in the cyanide has more covalent character than in the fluoride. This study additionally suggests that hydrides of other metal cyanide species are likely candidates

  18. X-ray sources in regions of star formation. 5: The low mass stars of the Upper Scorpius association

    NASA Technical Reports Server (NTRS)

    Walter, Frederick M.; Vrba, Frederick J.; Mathieu, Robert D.; Brown, Alexander; Myers, Philip C.

    1994-01-01

    We report followup investigations of Einstein x-ray observations of the Upper Scorpius OB association. We identify 28 low mass pre-main sequence stars as counterparts of x-ray sources in the approximately = 7 square degrees of the OB association observed. Based on kinematics and lithium abundances, these stars are low mass members of the OB association. We use optical spectra and optical and near-IR photometry to determine the stellar luminosities, effective temperatures, masses, and ages. We show that the bolometric corrections and effective temperatures of the G and K stars are consistent with those of subgiants. The low mass stars have isochronal ages of 1-2 Myr, depending on the choice of evolutionary models, with very small dispersion (sigma approximately = 1 Myr). This age is significantly younger than the 5-6 Myr found for the more massive B stars. The small dispersion in stellar ages, less than 10% the sound-crossing time of the association, suggests that star formation was triggered. We present two scenarios for star formation in this association. In the two-episode scenario, formation of the low mass stars was triggered by a supernova explosion, and the low mass stars form quickly, with high efficiency. Alternatively, high and low mass star formation was all initiated at the same time, some 5-6 Myr ago, and the apparent systematic age difference is an artifact of how the isochrones are dated. The effect of the supernova is to terminate mass accretion and yield an apparently coeval population. We show that the incompleteness in the x-ray sampling is about 65%, and is strongly dependent on stellar mass. After correction for incompleteness, we estimate there are about 2000 low mass members (stellar mass less than 2 solar mass) of this association. The mass function in this association is indistinguishable from that of the field. The ratio of naked to classical T Tauri stars is much larger than in Tau-Aur, and may be attributable to the local environment. We

  19. Time-Resolved Spectroscopy of Active Binary Stars

    NASA Technical Reports Server (NTRS)

    Brown, Alexander

    2000-01-01

    This NASA grant covered EUVE observing and data analysis programs during EUVE Cycle 5 GO observing. The research involved a single Guest Observer project 97-EUVE-061 "Time-Resolved Spectroscopy of Active Binary Stars". The grant provided funding that covered 1.25 months of the PI's salary. The activities undertaken included observation planning and data analysis (both temporal and spectral). This project was awarded 910 ksec of observing time to study seven active binary stars, all but one of which were actually observed. Lambda-And was observed on 1997 Jul 30 - Aug 3 and Aug 7-14 for a total of 297 ksec; these observations showed two large complex flares that were analyzed by Osten & Brown (1999). AR Psc, observed for 350 ksec on 1997 Aug 27 - Sep 13, showed only relatively small flares that were also discussed by Osten & Brown (1999). EUVE observations of El Eri were obtained on 1994 August 24-28, simultaneous with ASCA X-ray spectra. Four flares were detected by EUVE with one of these also observed simultaneously, by ASCA. The other three EUVE observations were of the stars BY Dra (1997 Sep 22-28), V478 Lyr (1998 May 18-27), and sigma Gem (1998 Dec 10-22). The first two stars showed a few small flares. The sigma Gem data shows a beautiful complete flare with a factor of ten peak brightness compared to quiescence. The flare rise and almost all the decay phase are observed. Unfortunately no observations in other spectral regions were obtained for these stars. Analysis of the lambda-And and AR Psc observations is complete and the results were published in Osten & Brown (1999). Analysis of the BY Dra, V478 Lyr and sigma Gem EUVE data is complete and will be published in Osten (2000, in prep.). The El Eri EUV analysis is also completed and the simultaneous EUV/X-ray study will be published in Osten et al. (2000, in prep.). Both these latter papers will be submitted in summer 2000. All these results will form part of Rachel Osten's PhD thesis.

  20. Near threshold {Lambda} and {Sigma}{sup 0} production in pp collisions

    SciTech Connect

    Gasparian, A.; Haidenbauer, J.; Hanhart, C.; Kondratyuk, L.; Speth, J.

    2000-12-31

    The reactions pp {yields} p{Lambda}K{sup +} and pp {yields} p{Sigma}{sup 0}K{sup +} are studied near their thresholds. The strangeness production process is described by the {pi}- and K exchange mechanisms. Effects from the final-state interaction in the hyperon-nucleon system are taken into account rigorously. It is shown that the experimentally observed strong suppression of {Sigma}{sup 0} production compared to {Lambda} production can be explained by a destructive interference between {pi} and K exchange in the reaction pp {yields} p{Sigma}{sup 0}K{sup +}.

  1. Modulation of serotonergic neurotransmission by short- and long-term treatments with sigma ligands.

    PubMed

    Bermack, J E; Debonnel, G

    2001-10-01

    1. Sigma receptors were first described in 1976 as opiate receptors but were later determined to be a distinct class of receptors with two subtypes, sigma(1) and sigma(2). Although the endogenous ligand is yet to be elucidated, the sigma(1) receptor has recently been cloned. 2. Behavioural models used to test potential antidepressants have shown sigma ligands to produce antidepressant effects but their mechanism of action is unknown. 3. The goal of the present study was to assess the effects of various sigma(1) ligands on the firing activity of serotonin (5-HT) neurons of the dorsal raphe nucleus (DRN) using extracellular in vivo recordings in anaesthetized rats. 4. The sigma(1) ligands (+)-pentazocine and 4-(N-benzylpiperidin-4-yl)-4-iodobenzamide (4-IBP) (2 mg kg(-1) day(-1)) increased markedly 5-HT firing activity after 2 days of treatment and maintained the same increased firing rate after long-term (21 days) treatments. Furthermore, the increased firing rate produced by 2 and 21 day treatments with (+)-pentazocine was prevented by the co-administration of N,N-dipropyl-2-(4-methoxy-3-(2-phenylethoxy)phenyl)-thylamine (NE-100) (10 mg kg(-1) day(-1)) a selective sigma(1) antagonist, confirming the sigma(1) receptor's modulation of these effects. In contrast, the sigma(1) ligands (+)-N-cyclopropylmethyl-N-methyl-1,4-diphenyl-1-1-ethyl-but-3-en-1-ylamine hydrochloride (JO-1784) and 2-(4-morpholinoethyl 1-phenyl-cyclohexane-1-carboxylate hydrochloride (PRE-084) had no effect. 5. Following a 21-day treatment with (+)-pentazocine there was a marked reduction in the number of neurons found per track. This decrease was not seen after chronic treatment with 4-IBP and may represent a depolarization block. 6. These results suggest a modulation of serotonergic neurotransmission by some sigma receptors and provide a potential mechanism for the 'antidepressant effects' reported and provide evidence toward sigma(1) ligands as potential antidepressants with a rapid onset of

  2. Modulation of serotonergic neurotransmission by short- and long-term treatments with sigma ligands.

    PubMed

    Bermack, J E; Debonnel, G

    2001-10-01

    1. Sigma receptors were first described in 1976 as opiate receptors but were later determined to be a distinct class of receptors with two subtypes, sigma(1) and sigma(2). Although the endogenous ligand is yet to be elucidated, the sigma(1) receptor has recently been cloned. 2. Behavioural models used to test potential antidepressants have shown sigma ligands to produce antidepressant effects but their mechanism of action is unknown. 3. The goal of the present study was to assess the effects of various sigma(1) ligands on the firing activity of serotonin (5-HT) neurons of the dorsal raphe nucleus (DRN) using extracellular in vivo recordings in anaesthetized rats. 4. The sigma(1) ligands (+)-pentazocine and 4-(N-benzylpiperidin-4-yl)-4-iodobenzamide (4-IBP) (2 mg kg(-1) day(-1)) increased markedly 5-HT firing activity after 2 days of treatment and maintained the same increased firing rate after long-term (21 days) treatments. Furthermore, the increased firing rate produced by 2 and 21 day treatments with (+)-pentazocine was prevented by the co-administration of N,N-dipropyl-2-(4-methoxy-3-(2-phenylethoxy)phenyl)-thylamine (NE-100) (10 mg kg(-1) day(-1)) a selective sigma(1) antagonist, confirming the sigma(1) receptor's modulation of these effects. In contrast, the sigma(1) ligands (+)-N-cyclopropylmethyl-N-methyl-1,4-diphenyl-1-1-ethyl-but-3-en-1-ylamine hydrochloride (JO-1784) and 2-(4-morpholinoethyl 1-phenyl-cyclohexane-1-carboxylate hydrochloride (PRE-084) had no effect. 5. Following a 21-day treatment with (+)-pentazocine there was a marked reduction in the number of neurons found per track. This decrease was not seen after chronic treatment with 4-IBP and may represent a depolarization block. 6. These results suggest a modulation of serotonergic neurotransmission by some sigma receptors and provide a potential mechanism for the 'antidepressant effects' reported and provide evidence toward sigma(1) ligands as potential antidepressants with a rapid onset of

  3. Dark stars: a review.

    PubMed

    Freese, Katherine; Rindler-Daller, Tanja; Spolyar, Douglas; Valluri, Monica

    2016-06-01

    Dark stars are stellar objects made (almost entirely) of hydrogen and helium, but powered by the heat from dark matter annihilation, rather than by fusion. They are in hydrostatic and thermal equilibrium, but with an unusual power source. Weakly interacting massive particles (WIMPs), among the best candidates for dark matter, can be their own antimatter and can annihilate inside the star, thereby providing a heat source. Although dark matter constitutes only [Formula: see text]0.1% of the stellar mass, this amount is sufficient to power the star for millions to billions of years. Thus, the first phase of stellar evolution in the history of the Universe may have been dark stars. We review how dark stars come into existence, how they grow as long as dark matter fuel persists, and their stellar structure and evolution. The studies were done in two different ways, first assuming polytropic interiors and more recently using the MESA stellar evolution code; the basic results are the same. Dark stars are giant, puffy (∼10 AU) and cool (surface temperatures  ∼10 000 K) objects. We follow the evolution of dark stars from their inception at  ∼[Formula: see text] as they accrete mass from their surroundings to become supermassive stars, some even reaching masses  >[Formula: see text] and luminosities  >[Formula: see text], making them detectable with the upcoming James Webb Space Telescope. Once the dark matter runs out and the dark star dies, it may collapse to a black hole; thus dark stars may provide seeds for the supermassive black holes observed throughout the Universe and at early times. Other sites for dark star formation may exist in the Universe today in regions of high dark matter density such as the centers of galaxies. The current review briefly discusses dark stars existing today, but focuses on the early generation of dark stars. PMID:27214049

  4. Dark stars: a review

    NASA Astrophysics Data System (ADS)

    Freese, Katherine; Rindler-Daller, Tanja; Spolyar, Douglas; Valluri, Monica

    2016-06-01

    Dark stars are stellar objects made (almost entirely) of hydrogen and helium, but powered by the heat from dark matter annihilation, rather than by fusion. They are in hydrostatic and thermal equilibrium, but with an unusual power source. Weakly interacting massive particles (WIMPs), among the best candidates for dark matter, can be their own antimatter and can annihilate inside the star, thereby providing a heat source. Although dark matter constitutes only ≲ 0.1% of the stellar mass, this amount is sufficient to power the star for millions to billions of years. Thus, the first phase of stellar evolution in the history of the Universe may have been dark stars. We review how dark stars come into existence, how they grow as long as dark matter fuel persists, and their stellar structure and evolution. The studies were done in two different ways, first assuming polytropic interiors and more recently using the MESA stellar evolution code; the basic results are the same. Dark stars are giant, puffy (˜10 AU) and cool (surface temperatures  ˜10 000 K) objects. We follow the evolution of dark stars from their inception at  ˜1{{M}⊙} as they accrete mass from their surroundings to become supermassive stars, some even reaching masses  >{{10}6}{{M}⊙} and luminosities  >{{10}10}{{L}⊙} , making them detectable with the upcoming James Webb Space Telescope. Once the dark matter runs out and the dark star dies, it may collapse to a black hole; thus dark stars may provide seeds for the supermassive black holes observed throughout the Universe and at early times. Other sites for dark star formation may exist in the Universe today in regions of high dark matter density such as the centers of galaxies. The current review briefly discusses dark stars existing today, but focuses on the early generation of dark stars.

  5. Dark stars: a review

    NASA Astrophysics Data System (ADS)

    Freese, Katherine; Rindler-Daller, Tanja; Spolyar, Douglas; Valluri, Monica

    2016-06-01

    Dark stars are stellar objects made (almost entirely) of hydrogen and helium, but powered by the heat from dark matter annihilation, rather than by fusion. They are in hydrostatic and thermal equilibrium, but with an unusual power source. Weakly interacting massive particles (WIMPs), among the best candidates for dark matter, can be their own antimatter and can annihilate inside the star, thereby providing a heat source. Although dark matter constitutes only ≲ 0.1% of the stellar mass, this amount is sufficient to power the star for millions to billions of years. Thus, the first phase of stellar evolution in the history of the Universe may have been dark stars. We review how dark stars come into existence, how they grow as long as dark matter fuel persists, and their stellar structure and evolution. The studies were done in two different ways, first assuming polytropic interiors and more recently using the MESA stellar evolution code; the basic results are the same. Dark stars are giant, puffy (∼10 AU) and cool (surface temperatures  ∼10 000 K) objects. We follow the evolution of dark stars from their inception at  ∼1{{M}ȯ} as they accrete mass from their surroundings to become supermassive stars, some even reaching masses  >{{10}6}{{M}ȯ} and luminosities  >{{10}10}{{L}ȯ} , making them detectable with the upcoming James Webb Space Telescope. Once the dark matter runs out and the dark star dies, it may collapse to a black hole; thus dark stars may provide seeds for the supermassive black holes observed throughout the Universe and at early times. Other sites for dark star formation may exist in the Universe today in regions of high dark matter density such as the centers of galaxies. The current review briefly discusses dark stars existing today, but focuses on the early generation of dark stars.

  6. Intergalactic Star Formation

    NASA Astrophysics Data System (ADS)

    Boquien, Médéric

    2007-11-01

    The work presented here is about star formation in the unusual environment of collisional debris studied for the first time as such. These peculiar regions have an interstellar medium, and in particular a metallicity, similar to that of star forming regions in galactic discs while not undergoing similar environment effects such as density waves in the spiral arms for instance. This study has been conducted with a selection of exceptional systems that have ejected large quantities of gas into the intergalactic medium while also showing some intergalactic star forming regions. Principal Investigator as well as archive spectroscopy and imaging from multi-wavelength observations ranging from far ultraviolet to mid-infrared have been used. Withal a model has been built in order to reproduce the spectral energy distributions of intergalactic star forming regions and constrain the star formation histories, their extinctions and their fraction of stars coming from the parent galaxies' discs. Comparisons have been performed on the estimation of star formation rates between infrared, Halpha and ultraviolet wavelengths. This thesis has brought the following main new results: * some regions seem to be deprived of any old stellar population, and these are ideal laboratories in which to study star formation ; * the mid-infrared star formation rate estimator is as reliable as it is in spiral galaxies ; * the scatter in the estimation of star formation rates in various bands is similar to that of spiral galaxies and is mainly due to age effects ; * the combination of the extinction uncorrected Halpha line with mid-infrared yields a good estimation of the actual star formation rate ; * an important part of star formation, which can be as high as 85%, takes place in the intergalactic medium showing that in a young universe, in which this type of system is much more common than in the nearby universe, star formation from collisional debris can be an important factor of enrichment of

  7. Dark stars: a review.

    PubMed

    Freese, Katherine; Rindler-Daller, Tanja; Spolyar, Douglas; Valluri, Monica

    2016-06-01

    Dark stars are stellar objects made (almost entirely) of hydrogen and helium, but powered by the heat from dark matter annihilation, rather than by fusion. They are in hydrostatic and thermal equilibrium, but with an unusual power source. Weakly interacting massive particles (WIMPs), among the best candidates for dark matter, can be their own antimatter and can annihilate inside the star, thereby providing a heat source. Although dark matter constitutes only [Formula: see text]0.1% of the stellar mass, this amount is sufficient to power the star for millions to billions of years. Thus, the first phase of stellar evolution in the history of the Universe may have been dark stars. We review how dark stars come into existence, how they grow as long as dark matter fuel persists, and their stellar structure and evolution. The studies were done in two different ways, first assuming polytropic interiors and more recently using the MESA stellar evolution code; the basic results are the same. Dark stars are giant, puffy (∼10 AU) and cool (surface temperatures  ∼10 000 K) objects. We follow the evolution of dark stars from their inception at  ∼[Formula: see text] as they accrete mass from their surroundings to become supermassive stars, some even reaching masses  >[Formula: see text] and luminosities  >[Formula: see text], making them detectable with the upcoming James Webb Space Telescope. Once the dark matter runs out and the dark star dies, it may collapse to a black hole; thus dark stars may provide seeds for the supermassive black holes observed throughout the Universe and at early times. Other sites for dark star formation may exist in the Universe today in regions of high dark matter density such as the centers of galaxies. The current review briefly discusses dark stars existing today, but focuses on the early generation of dark stars.

  8. Star-Formation in Low Radio Luminosity AGN from the Sloan Digital Sky Survey

    SciTech Connect

    de Vries, W H; Hodge, J A; Becker, R H; White, R L; Helfand, D J

    2007-04-18

    We investigate faint radio emission from low- to high-luminosity Active Galactic Nuclei (AGN) selected from the Sloan Digital Sky Survey (SDSS). Their radio properties are inferred by coadding large ensembles of radio image cut-outs from the FIRST survey, as almost all of the sources are individually undetected. We correlate the median radio flux densities against a range of other sample properties, including median values for redshift, [O III] luminosity, emission line ratios, and the strength of the 4000{angstrom} break. We detect a strong trend for sources that are actively undergoing star-formation to have excess radio emission beyond the {approx} 10{sup 28} ergs s{sup -1} Hz{sup -1} level found for sources without any discernible star-formation. Furthermore, this additional radio emission correlates well with the strength of the 4000{angstrom} break in the optical spectrum, and may be used to assess the age of the star-forming component. We examine two subsamples, one containing the systems with emission line ratios most like star-forming systems, and one with the sources that have characteristic AGN ratios. This division also separates the mechanism responsible for the radio emission (star-formation vs. AGN). For both cases we find a strong, almost identical, correlation between [O III] and radio luminosity, with the AGN sample extending toward lower, and the star-formation sample toward higher luminosities. A clearer separation between the two subsamples is seen as function of the central velocity dispersion {sigma} of the host galaxy. For systems at similar redshifts and values of {sigma}, the star-formation subsample is brighter than the AGN in the radio by an order of magnitude. This underlines the notion that the radio emission in star-forming systems can dominate the emission associated with the AGN.

  9. Star formation regions in galaxies: Star complexes and spiral arms

    NASA Astrophysics Data System (ADS)

    Efremov, Iurii N.

    This book describes observational data on star formation regions (from young star clusters to spiral arms) in the Milky Way and other galaxies. It is concluded that not only high-luminosity stars but also star clusters and associations are forming together in vast complexes. It is claimed that these complexes are the primary, fundamental entities of star formation.

  10. The A6Sigma+ - X6Sigma+ Transition of CrH, Einstein Coefficients and an Improved Description of the A State

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Ram, R. S.; Bernath, Peter F.; Parsons, C. G.; Galehouse, D.; Arnold, James O. (Technical Monitor)

    2001-01-01

    The spectrum of CrH has been reinvestigated in the 9000-15000/cm region using the Fourier transform spectrometer of the National Solar Observatory. The 1-0 and 1-1 bands of the A6Sigma+ - X6Sigma+ transition have been measured and improved spectroscopic constants have been determined. A value for the 2-0 band origin has been obtained from the band head using estimated spectroscopic constants. These data provide a set of much improved equilibrium vibrational and rotational constants for the A6Sigma+ state. An accurate description of the A-X transition has been obtained using a multi-reference configuration interaction approach. The inclusion of both scalar relativity and Cr 3s3p correlation are required to obtain a good description of both states. The ab initio computed Einstein coefficients and radiative lifetimes are reported.

  11. A VLA radio-continuum survey of a sample of confirmed and marginal barium stars

    NASA Technical Reports Server (NTRS)

    Drake, Stephen A.; Simon, Theodore; Linsky, Jeffrey L.

    1987-01-01

    Results are reported from a 6-cm VLA survey of five confirmed Ba II stars and eight mild Ba II stars, undertaken to search for evidence of gyrosynchrotron emission or thermal emission from the primary star's wind that is enhanced or photoionized by a white dwarf companion. Of these 13 stars, only Beta UMi was detected as a possible radio source at a flux level of 0.11 mJy (3sigma). The 6-cm radio luminosities (L6) of the other stars are as small as log L6 less than or equal to 14.0 and are an order of magnitude or more lower than the average levels found in RS CVn systems, but are consistent with the L6 upper limits previously found for stars of spectral type similar to the Ba II stars and normal elemental abundances. The upper limit to the radio luminosity for the possible mild Ba II star 56 Peg, when combined with its previously known X-ray luminosity, may provide useful constraints on the various models that have been proposed for this interesting object, once its orbital period is known.

  12. THE NATURE OF HYPERVELOCITY STARS AND THE TIME BETWEEN THEIR FORMATION AND EJECTION

    SciTech Connect

    Brown, Warren R.; Geller, Margaret J.; Kenyon, Scott J.; Cohen, Judith G. E-mail: mgeller@cfa.harvard.edu E-mail: jlc@astro.caltech.edu

    2012-07-20

    We obtain Keck HIRES spectroscopy of HVS5, one of the fastest unbound stars in the Milky Way halo. We show that HVS5 is a 3.62 {+-} 0.11 M{sub Sun} main-sequence B star at a distance of 50 {+-} 5 kpc. The difference between its age and its flight time from the Galactic center is 105 {+-} 18 (stat) {+-}30 (sys) Myr; flight times from locations elsewhere in the Galactic disk are similar. This 10{sup 8} yr 'arrival time' between formation and ejection is difficult to reconcile with any ejection scenario involving massive stars that live for only 10{sup 7} yr. For comparison, we derive arrival times of 10{sup 7} yr for two unbound runaway B stars, consistent with their disk origin where ejection results from a supernova in a binary system or dynamical interactions between massive stars in a dense star cluster. For HVS5, ejection during the first 10{sup 7} yr of its lifetime is ruled out at the 3{sigma} level. Together with the 10{sup 8} yr arrival times inferred for three other well-studied hypervelocity stars (HVSs), these results are consistent with a Galactic center origin for the HVSs. If the HVSs were indeed ejected by the central black hole, then the Galactic center was forming stars {approx_equal}200 Myr ago, and the progenitors of the HVSs took {approx_equal}100 Myr to enter the black hole's loss cone.

  13. STAR in CTO PCI: When is STAR not a star?

    PubMed

    Hira, Ravi S; Dean, Larry S

    2016-04-01

    Subintimal tracking and reentry (STAR) has been used as a bailout strategy and involves an uncontrolled dissection and recanalization into the distal lumen to reestablish vessel patency. In the current study, thrombolysis in myocardial infarction (TIMI) flow < 3 was the only variable which they found to be significantly associated with restenosis and reocclusion after stent placement. It may be reasonable to consider second generation drug eluting stent placement in patients receiving STAR that have TIMI 3 flow, however, this should only be done if there is no compromise of major side branches. If unsure, we recommend to perform balloon angioplasty without stenting.

  14. The First Stars

    NASA Astrophysics Data System (ADS)

    Yoshida, Naoki

    2010-10-01

    The standard cosmological model predicts that the first cosmological objects are formed when the age of the universe is a few hundred million years. Recent theoretical studies and numerical simulations consistently suggest that the first objects are very massive primordial stars. We introduce the key physics and explain why the first stars are thought to be massive, rather than to be low-mass stars. The state-of-the-art simulations include all the relevant atomic and molecular physics to follow the thermal evolution of a prestellar gas cloud to very high ``stellar'' densities. Evolutionary calculations of the primordial stars suggest the formation of massive blackholes in the early universe. Finally, we show the results from high-resolution simulations of star formation in a low-metallicity gas. Vigorous fragmentation is triggered in a star-forming gas cloud at a metallicity of as low as Z = 10-5Zsolar.

  15. Discovery of a magnetic field in the early B-type star σ Lupi

    NASA Astrophysics Data System (ADS)

    Henrichs, H. F.; Kolenberg, K.; Plaggenborg, B.; Marsden, S. C.; Waite, I. A.; Landstreet, J. D.; Wade, G. A.; Grunhut, J. H.; Oksala, M. E.

    2012-09-01

    Context. Magnetic early B-type stars are rare. Indirect indicators are needed to identify them before investing in time-intensive spectropolarimetric observations. Aims: We use the strongest indirect indicator of a magnetic field in B stars, which is periodic variability of ultraviolet (UV) stellar wind lines occurring symmetric about the approximate rest wavelength. Our aim is to identify probable magnetic candidates which would become targets for follow-up spectropolarimetry to search for a magnetic field. Methods: From the UV wind line variability the B1/B2V star σ Lupi emerged as a new magnetic candidate star. AAT spectropolarimetric measurements with SEMPOL were obtained. The longitudinal component of the magnetic field integrated over the visible surface of the star was determined with the least-squares deconvolution method. Results: The UV line variations of σ Lupi are similar to what is known in magnetic B stars, but no periodicity could be determined. We detected a varying longitudinal magnetic field with amplitude of about 100 G with error bars of typically 20 G, which supports an oblique magnetic-rotator configuration. The equivalent width variations of the UV lines, the magnetic and the optical-line variations are consistent with the photometric period of 3.02 d, which we identify with the rotation period of the star. Additional observations with ESPaDOnS attached to the CFHT confirmed this discovery, and allowed the determination of a precise magnetic period. Analysis revealed that σ Lupi is a helium-strong star, with an enhanced nitrogen abundance and an underabundance of carbon, and has a chemically spotted surface. Conclusions.σ Lupi is a magnetic oblique rotator, and is a He-strong star. Like in other magnetic B stars the UV wind emission appears to originate close to the magnetic equatorial plane, with maximum emission occurring when a magnetic pole points towards the Earth. The 3.01972 ± 0.00043 d magnetic rotation period is consistent with

  16. Kinematic Evolution of Simulated Star-Forming Galaxies

    NASA Technical Reports Server (NTRS)

    Kassin, Susan A.; Brooks, Alyson; Governato, Fabio; Weiner, Benjamin J.; Gardner, Jonathan P.

    2014-01-01

    Recent observations have shown that star-forming galaxies like our own Milky Way evolve kinematically into ordered thin disks over the last approximately 8 billion years since z = 1.2, undergoing a process of "disk settling." For the first time, we study the kinematic evolution of a suite of four state of the art "zoom in" hydrodynamic simulations of galaxy formation and evolution in a fully cosmological context and compare with these observations. Until now, robust measurements of the internal kinematics of simulated galaxies were lacking as the simulations suffered from low resolution, overproduction of stars, and overly massive bulges. The current generation of simulations has made great progress in overcoming these difficulties and is ready for a kinematic analysis. We show that simulated galaxies follow the same kinematic trends as real galaxies: they progressively decrease in disordered motions (sigma(sub g)) and increase in ordered rotation (V(sub rot)) with time. The slopes of the relations between both sigma(sub g) and V(sub rot) with redshift are consistent between the simulations and the observations. In addition, the morphologies of the simulated galaxies become less disturbed with time, also consistent with observations. This match between the simulated and observed trends is a significant success for the current generation of simulations, and a first step in determining the physical processes behind disk settling.

  17. Topics in conformal invariance and generalized sigma models

    SciTech Connect

    Bernardo, L M

    1997-05-01

    This thesis consists of two different parts, having in common the fact that in both, conformal invariance plays a central role. In the first part, the author derives conditions for conformal invariance, in the large N limit, and for the existence of an infinite number of commuting classical conserved quantities, in the Generalized Thirring Model. The treatment uses the bosonized version of the model. Two different approaches are used to derive conditions for conformal invariance: the background field method and the Hamiltonian method based on an operator algebra, and the agreement between them is established. The author constructs two infinite sets of non-local conserved charges, by specifying either periodic or open boundary conditions, and he finds the Poisson Bracket algebra satisfied by them. A free field representation of the algebra satisfied by the relevant dynamical variables of the model is also presented, and the structure of the stress tensor in terms of free fields (and free currents) is studied in detail. In the second part, the author proposes a new approach for deriving the string field equations from a general sigma model on the world sheet. This approach leads to an equation which combines some of the attractive features of both the renormalization group method and the covariant beta function treatment of the massless excitations. It has the advantage of being covariant under a very general set of both local and non-local transformations in the field space. The author applies it to the tachyon, massless and first massive level, and shows that the resulting field equations reproduce the correct spectrum of a left-right symmetric closed bosonic string.

  18. CONSTRAINTS ON LONG-PERIOD PLANETS FROM AN L'- AND M-BAND SURVEY OF NEARBY SUN-LIKE STARS: OBSERVATIONS

    SciTech Connect

    Heinze, A. N.; Hinz, Philip M.; Sivanandam, Suresh; Kenworthy, Matthew; Miller, Douglas; Meyer, Michael E-mail: phinz@as.arizona.ed E-mail: mkenworthy@as.arizona.ed E-mail: mmeyer@phys.ethz.c

    2010-05-10

    We present the observational results of an L'- and M-band adaptive optics imaging survey of 54 nearby, Sun-like stars for extrasolar planets, carried out using the Clio camera on the MMT. We have concentrated more strongly than all other planet-imaging surveys to date on very nearby F, G, and K stars, prioritizing stellar proximity higher than youth. Ours is also the first survey to include extensive observations in the M band, which supplement the primary L' observations. Models predict much better planet/star flux ratios at the L' and M bands than at more commonly used shorter wavelengths (i.e., the H band). We have carried out extensive blind simulations with fake planets inserted into the raw data to verify our sensitivity, and to establish a definitive relationship between source significance in {sigma} and survey completeness. We find 97% confident-detection completeness for 10{sigma} sources, but only 46% for 7{sigma} sources-raising concerns about the standard procedure of assuming high completeness at 5{sigma}, and demonstrating that blind sensitivity tests to establish the significance-completeness relation are an important analysis step for all planet-imaging surveys. We discovered a previously unknown {approx}0.15 M{sub sun} stellar companion to the F9 star GJ 3876, at a projected separation of about 80 AU. Twelve additional candidate faint companions are detected around other stars. Of these, 11 are confirmed to be background stars and one is a previously known brown dwarf. We obtained sensitivity to planetary-mass objects around almost all of our target stars, with sensitivity to objects below 3 M{sub Jup} in the best cases. Constraints on planet populations based on this null result are presented in our Modeling Results paper.

  19. Strange nonchaotic stars.

    PubMed

    Lindner, John F; Kohar, Vivek; Kia, Behnam; Hippke, Michael; Learned, John G; Ditto, William L

    2015-02-01

    The unprecedented light curves of the Kepler space telescope document how the brightness of some stars pulsates at primary and secondary frequencies whose ratios are near the golden mean, the most irrational number. A nonlinear dynamical system driven by an irrational ratio of frequencies generically exhibits a strange but nonchaotic attractor. For Kepler's "golden" stars, we present evidence of the first observation of strange nonchaotic dynamics in nature outside the laboratory. This discovery could aid the classification and detailed modeling of variable stars.

  20. Electron-phonon interaction in two dimensions: Variation of Im[Sigma]([epsilon][sub [ital p

    SciTech Connect

    Kostur, V.N.; Mitrovic, B. )

    1993-12-01

    The interaction between phonons and a two-dimensional (2D) electron gas is studied beyond the Migdal approximation. The analysis of the vertex function leads to the relative correction of [vert bar]Im[Sigma]([epsilon][sub [ital p

  1. Distinguishing between chi and sigma phases in duplex stainless steels using potentiostatic etching

    SciTech Connect

    Jackson, E.M.L.E.M.; Visser, P.E. de . Physical Metallurgy Div.); Cornish, L.A. )

    1993-12-01

    A color interference film etching technique based on the principle of potentiostatic etching has been developed to distinguish, by optical metallography, between Cr-rich sigma and Mo-rich chi phases as well as with simultaneous identification of the ferrite and austenite phases in duplex stainless steels. The optical metallography results are confirmed by semiquantitative energy dispersive spectrometry analysis and back-scattered electron imaging. The technique is relatively simple and rapid, and makes use of low voltages and a hot etchant. Results have shown distinctively the sigma, chi, ferrite, and austenite phases, and enable observation of the microstructural development, morphology, and kinetics of formation of the phases in duplex alloys. The method, by giving excellent color contrast between sigma and chi, also facilitates quantitative image analysis of the sigma and chi volume fractions.

  2. 78 FR 32458 - Manufacturer of Controlled Substances; Notice of Registration; Sigma Aldrich Research...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-30

    ... February 21, 2013, 78 FR 12102, Sigma ] Aldrich Research Biochemicals, Inc., 1-3 Strathmore Road, Natick...-Methylenedioxymethamphetamine (MDMA) I (7405). Psilocybin (7437) I 5-Methoxy-N,N-diisopropyltryptamine (7439). I 1-...

  3. The Statistical point of view of Quality: the Lean Six Sigma methodology

    PubMed Central

    Viti, Andrea; Terzi, Alberto

    2015-01-01

    Six Sigma and Lean are two quality improvement methodologies. The Lean Six Sigma methodology is applicable to repetitive procedures. Therefore, the use of this methodology in the health-care arena has focused mainly on areas of business operations, throughput, and case management and has focused on efficiency outcomes. After the revision of methodology, the paper presents a brief clinical example of the use of Lean Six Sigma as a quality improvement method in the reduction of the complications during and after lobectomies. Using Lean Six Sigma methodology, the multidisciplinary teams could identify multiple modifiable points across the surgical process. These process improvements could be applied to different surgical specialties and could result in a measurement, from statistical point of view, of the surgical quality. PMID:25973253

  4. The Statistical point of view of Quality: the Lean Six Sigma methodology.

    PubMed

    Bertolaccini, Luca; Viti, Andrea; Terzi, Alberto

    2015-04-01

    Six Sigma and Lean are two quality improvement methodologies. The Lean Six Sigma methodology is applicable to repetitive procedures. Therefore, the use of this methodology in the health-care arena has focused mainly on areas of business operations, throughput, and case management and has focused on efficiency outcomes. After the revision of methodology, the paper presents a brief clinical example of the use of Lean Six Sigma as a quality improvement method in the reduction of the complications during and after lobectomies. Using Lean Six Sigma methodology, the multidisciplinary teams could identify multiple modifiable points across the surgical process. These process improvements could be applied to different surgical specialties and could result in a measurement, from statistical point of view, of the surgical quality.

  5. 77 FR 31390 - Manufacturer of Controlled Substances; Notice of Registration; Sigma Aldrich Research...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-25

    ... February 6, 2012, 77 FR 5847, Sigma Aldrich Research Biochemicals, Inc., 1-3 Strathmore Road, Natick...-diisopropyltryptamine (7439)....... I 1- piperidine (7470)..... I N-Benzylpiperazine (7493) I Heroin (9200)...

  6. Differential Photoproduction Cross Sections of the Sigma0(1385), Lambda(1405), and Lambda(1520)

    SciTech Connect

    Moriya, Kei; Schumacher, Reinhard A.

    2013-10-01

    We report the exclusive photoproduction cross sections for the Sigma(1385), Lambda(1405), and Lambda(1520) in the reactions gamma + p -> K+ + Y* using the CLAS detector for energies from near the respective production thresholds up to a center-of-mass energy W of 2.85 GeV. The differential cross sections are integrated to give the total exclusive cross sections for each hyperon. Comparisons are made to current theoretical models based on the effective Lagrangian approach and fitted to previous data. The accuracy of these models is seen to vary widely. The cross sections for the Lambda(1405) region are strikingly different for the Sigma+pi-, Sigma0 pi0, and Sigma- pi+ decay channels, indicating the effect of isospin interference, especially at W values close to the threshold.

  7. Is Lebesgue measure the only [sigma]-finite invariant Borel measure?

    NASA Astrophysics Data System (ADS)

    Elekes, Marton; Keleti, Tamas

    2006-09-01

    S. Saks and recently R.D. Mauldin asked if every translation invariant [sigma]-finite Borel measure on is a constant multiple of Lebesgue measure. The aim of this paper is to investigate the versions of this question, since surprisingly the answer is "yes and no," depending on what we mean by Borel measure and by constant. According to a folklore result, if the measure is only defined for Borel sets, then the answer is affirmative. We show that if the measure is defined on a [sigma]-algebra containing the Borel sets, then the answer is negative. However, if we allow the multiplicative constant to be infinity, then the answer is affirmative in this case as well. Moreover, our construction also shows that an isometry invariant [sigma]-finite Borel measure (in the wider sense) on can be non-[sigma]-finite when we restrict it to the Borel sets.

  8. Massive soliton stars

    NASA Technical Reports Server (NTRS)

    Chiu, Hong-Yee

    1990-01-01

    The structure of nontopological solutions of Einstein field equations as proposed by Friedberg, Lee, and Pang (1987) is examined. This analysis incorporates finite temperature effects and pair creation. Quarks are assumed to be the only species that exist in interior of soliton stars. The possibility of primordial creation of soliton stars in the incomplete decay of the degenerate vacuum in early universe is explored. Because of dominance of pair creation inside soliton stars, the luminosity of soliton stars is not determined by its radiative transfer characteristics, and the surface temperature of soliton stars can be the same as its interior temperature. It is possible that soliton stars are intense X-ray radiators at large distances. Soliton stars are nearly 100 percent efficient energy converters, converting the rest energy of baryons entering the interior into radiation. It is possible that a sizable number of baryons may also be trapped inside soliton stars during early epochs of the universe. In addition, if soliton stars exist they could assume the role played by massive black holes in galactic centers.

  9. Delta Scuti stars: Theory

    SciTech Connect

    Guzik, J.A.

    1998-03-01

    The purpose of asteroseismology is not only to derive the internal structure of individual stars from their observed oscillation frequencies, but also to test and extend one`s understanding of the physics of matter under the extremes of temperature, density, and pressure found in stellar interiors. In this review, the author hopes to point out what one can learn about the Sun by studying {delta} Scuti stars, as well as what one can learn about stars more massive or evolved than the Sun. He discusses some of the difficulties in theoretical approaches to asteroseismology for {delta} Scuti stars, using FG Vir, {delta} Scuti, and CD-24{degree} 7599 as examples.

  10. Massive soliton stars

    SciTech Connect

    Chiu, Hongyee )

    1990-05-01

    The structure of nontopological solutions of Einstein field equations as proposed by Friedberg, Lee, and Pang (1987) is examined. This analysis incorporates finite temperature effects and pair creation. Quarks are assumed to be the only species that exist in interior of soliton stars. The possibility of primordial creation of soliton stars in the incomplete decay of the degenerate vacuum in early universe is explored. Because of dominance of pair creation inside soliton stars, the luminosity of soliton stars is not determined by its radiative transfer characteristics, and the surface temperature of soliton stars can be the same as its interior temperature. It is possible that soliton stars are intense X-ray radiators at large distances. Soliton stars are nearly 100 percent efficient energy converters, converting the rest energy of baryons entering the interior into radiation. It is possible that a sizable number of baryons may also be trapped inside soliton stars during early epochs of the universe. In addition, if soliton stars exist they could assume the role played by massive black holes in galactic centers. 27 refs.

  11. Introduction to neutron stars

    SciTech Connect

    Lattimer, James M.

    2015-02-24

    Neutron stars contain the densest form of matter in the present universe. General relativity and causality set important constraints to their compactness. In addition, analytic GR solutions are useful in understanding the relationships that exist among the maximum mass, radii, moments of inertia, and tidal Love numbers of neutron stars, all of which are accessible to observation. Some of these relations are independent of the underlying dense matter equation of state, while others are very sensitive to the equation of state. Recent observations of neutron stars from pulsar timing, quiescent X-ray emission from binaries, and Type I X-ray bursts can set important constraints on the structure of neutron stars and the underlying equation of state. In addition, measurements of thermal radiation from neutron stars has uncovered the possible existence of neutron and proton superfluidity/superconductivity in the core of a neutron star, as well as offering powerful evidence that typical neutron stars have significant crusts. These observations impose constraints on the existence of strange quark matter stars, and limit the possibility that abundant deconfined quark matter or hyperons exist in the cores of neutron stars.

  12. Strange Nonchaotic Stars

    NASA Astrophysics Data System (ADS)

    Lindner, John F.; Kohar, Vivek; Kia, Behnam; Hippke, Michael; Learned, John G.; Ditto, William L.

    2015-08-01

    Exploiting the unprecedented capabilities of the planet-hunting Kepler space telescope, which stared at 150 000 stars for four years, we discuss recent evidence that certain stars dim and brighten in complex patterns with fractal features. Such stars pulsate at primary and secondary frequencies whose ratios are near the famous golden mean, the most irrational number. A nonlinear system driven by an irrational ratio of frequencies is generically attracted toward a “strange” behavior that is geometrically fractal without displaying the “butterfly effect” of chaos. Strange nonchaotic attractors have been observed in laboratory experiments and have been hypothesized to describe the electrochemical activity of the brain, but a bluish white star 16 000 light years from Earth in the constellation Lyra may manifest, in the scale-free distribution of its minor frequency components, the first strange nonchaotic attractor observed in the wild. The recognition of stellar strange nonchaotic dynamics may improve the classification of these stars and refine the physical modeling of their interiors. We also discuss nonlinear analysis of other RR Lyrae stars in Kepler field of view and discuss some toy models for modeling these stars.References: 1) Hippke, Michael, et al. "Pulsation period variations in the RRc Lyrae star KIC 5520878." The Astrophysical Journal 798.1 (2015): 42.2) Lindner, John F., et al. "Strange nonchaotic stars." Phys. Rev. Lett. 114, 054101 (2015)

  13. Combinations of 148 navigation stars and the star tracker

    NASA Technical Reports Server (NTRS)

    Duncan, R.

    1980-01-01

    The angular separation of all star combinations for 148 nav star on the onboard software for space transportation system-3 flight and following missions is presented as well as the separation of each pair that satisfies the viewing constraints of using both star trackers simultaneously. Tables show (1) shuttle star catalog 1980 star position in M 1950 coordinates; (2) two star combination of 148 nav stars; and (3) summary of two star-combinations of the star tracker 5 deg filter. These 148 stars present 10,875 combinations. For the star tracker filters of plus or minus 5 deg, there are 875 combinations. Formalhaut (nav star 26) has the best number of combinations, which is 33.

  14. Purification, molecular cloning, and expression of the mammalian sigma1-binding site.

    PubMed Central

    Hanner, M; Moebius, F F; Flandorfer, A; Knaus, H G; Striessnig, J; Kempner, E; Glossmann, H

    1996-01-01

    Sigma-ligands comprise several chemically unrelated drugs such as haloperidol, pentazocine, and ditolylguanidine, which bind to a family of low molecular mass proteins in the endoplasmic reticulum. These so-called sigma-receptors are believed to mediate various pharmacological effects of sigma-ligands by as yet unknown mechanisms. Based on their opposite enantioselectivity for benzomorphans and different molecular masses, two subtypes are differentiated. We purified the sigma1-binding site as a single 30-kDa protein from guinea pig liver employing the benzomorphan(+)[3H]pentazocine and the arylazide (-)[3H]azidopamil as specific probes. The purified (+)[3H]pentazocine-binding protein retained its high affinity for haloperidol, pentazocine, and ditolylguanidine. Partial amino acid sequence obtained after trypsinolysis revealed no homology to known proteins. Radiation inactivation of the pentazocine-labeled sigma1-binding site yielded a molecular mass of 24 +/- 2 kDa. The corresponding cDNA was cloned using degenerate oligonucleotides and cDNA library screening. Its open reading frame encoded a 25.3-kDa protein with at least one putative transmembrane segment. The protein expressed in yeast cells transformed with the cDNA showed the pharmacological characteristics of the brain and liver sigma1-binding site. The deduced amino acid sequence was structurally unrelated to known mammalian proteins but it shared homology with fungal proteins involved in sterol synthesis. Northern blots showed high densities of the sigma1-binding site mRNA in sterol-producing tissues. This is also in agreement with the known ability of sigma1-binding sites to interact with steroids, such as progesterone. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:8755605

  15. DO QUIESCENT AND ACTIVE GALAXIES HAVE DIFFERENT M{sub BH}-{sigma}{sub *} RELATIONS?

    SciTech Connect

    Woo, Jong-Hak; Park, Daeseong; Kang, Wol-Rang; Schulze, Andreas; Kim, Sang Chul; Riechers, Dominik A.

    2013-07-20

    To investigate the validity of the assumption that quiescent galaxies and active galaxies follow the same black hole mass (M{sub BH})-stellar velocity dispersion ({sigma}{sub *}) relation, as required for the calibration of M{sub BH} estimators for broad line active galactic nuclei (AGNs), we determine and compare the M{sub BH}-{sigma}{sub *} relations, respectively, for quiescent and active galaxies. For the quiescent galaxy sample, composed of 72 dynamical M{sub BH} measurements, we update {sigma}{sub *} for 28 galaxies using homogeneous H-band measurements that are corrected for galaxy rotation. For active galaxies, we collect 25 reverberation-mapped AGNs and improve {sigma}{sub *} measurement for two objects. Combining the two samples, we determine the virial factor f, first by scaling the active galaxy sample to the M{sub BH}-{sigma}{sub *} relation of quiescent galaxies, and second by simultaneously fitting the quiescent and active galaxy samples, as f=5.1{sub -1.1}{sup +1.5} and f=5.9{sub -1.5}{sup +2.1}, respectively. The M{sub BH}-{sigma}{sub *} relation of active galaxies appears to be shallower than that of quiescent galaxies. However, the discrepancy is caused by a difference in the accessible M{sub BH} distribution at given {sigma}{sub *}, primarily due to the difficulty of measuring reliable stellar velocity dispersion for the host galaxies of luminous AGNs. Accounting for the selection effects, we find that active and quiescent galaxies are consistent with following intrinsically the same M{sub BH}-{sigma}{sub *} relation.

  16. Properties of the bound {Lambda}({Sigma}){ital NN} system and hyperon-nucleon interactions

    SciTech Connect

    Miyagawa, K.; Kamada, H.; Gloeckle, W.; Stoks, V.

    1995-06-01

    The Faddeev equations for the hypertriton are solved precisely using the Nijmegen hyperon-nucleon and realistic {ital NN} interactions. The hypertriton turns out to be bound at the experimental value. Thereby the {Lambda}-{Sigma} conversion is crucial. States of the {Lambda}({Sigma}){ital NN} system with quantum numbers ({ital T},{ital J}) different from (0,1/2) are not bound. We visualized properties of the hypertriton wave function in various ways.

  17. Comparison of Sigma-Point and Extended Kalman Filters on a Realistic Orbit Determination Scenario

    NASA Technical Reports Server (NTRS)

    Gaebler, John; Hur-Diaz. Sun; Carpenter, Russell

    2010-01-01

    Sigma-point filters have received a lot of attention in recent years as a better alternative to extended Kalman filters for highly nonlinear problems. In this paper, we compare the performance of the additive divided difference sigma-point filter to the extended Kalman filter when applied to orbit determination of a realistic operational scenario based on the Interstellar Boundary Explorer mission. For the scenario studied, both filters provided equivalent results. The performance of each is discussed in detail.

  18. YOUNG BROWN DWARFS AT HIGH CADENCE: WARM SPITZER TIME SERIES MONITORING OF VERY LOW MASS {sigma} ORIONIS CLUSTER MEMBERS

    SciTech Connect

    Cody, Ann Marie; Hillenbrand, Lynne A.

    2011-11-01

    The continuous temporal coverage and high photometric precision afforded by space observatories have opened up new opportunities for the study of variability processes in young stellar cluster members. Of particular interest is the phenomenon of deuterium-burning pulsation in brown dwarfs (BDs) and very low mass stars, whose existence on 1-4 hr timescales has been proposed but not yet borne out by observations. To investigate short-timescale variability in young, low-mass objects, we carried out high-precision, high-cadence time series monitoring with the Warm Spitzer mission on 14 low mass stars and BDs in the {approx}3 Myr {sigma} Orionis cluster. The flux in many of our raw light curves is strongly correlated with subpixel position and can vary systematically by as much as 10%. We present a new approach to disentangle true stellar variability from this 'pixel-phase effect', which is more pronounced in Warm Spitzer observations as compared to the cryogenic mission. The light curves after correction reveal that most of the sample is devoid of variability down to the few-millimagnitude (mmag) level, on the minute to day timescales probed. However, one exceptional BD displays erratic brightness changes at the 10%-15% level, suggestive of variable obscuration by dusty material. The uninterrupted 24 hr datastream and sub-1% photometric precision enable limits on pulsation in the near-infrared. If this phenomenon is present in our light curves, then its amplitude must lie below 2-3 mmag. In addition, we present three field eclipsing binaries and one pulsator for which optical ground-based data are also available.

  19. Modulation of cellular calcium by sigma-2 receptors: release from intracellular stores in human SK-N-SH neuroblastoma cells.

    PubMed

    Vilner, B J; Bowen, W D

    2000-03-01

    Human SK-N-SH neuroblastoma cells expressed sigma-1 and sigma-2 receptors with similar pharmacological profiles to those of rodent-derived tissues, although sigma-2 receptors exhibited some affinity differences that might suggest heterogeneity or species differences. Structurally diverse sigma ligands produced two types of increases in intracellular (cytosolic) Ca(2+) concentration ([Ca(2+)](i)) in these cells. CB-64D, CB-64L, JL-II-147, BD737, LR172, BD1008, haloperidol, reduced haloperidol, and ibogaine all produced an immediate, dose-dependent, and transient rise in [Ca(2+)](i). Sigma-inactive compounds structurally similar to the most active sigma ligands and ligands for several neurotransmitter receptors produced little or no effect. The high activity of CB-64D and ibogaine (sigma-2-selective ligands) compared with the low activity of (+)-pentazocine and other (+)-benzomorphans (sigma-1-selective ligands), in addition to enantioselectivity for CB-64D over CB-64L, strongly indicated mediation by sigma-2 receptors. The effect of CB-64D and BD737 was blocked by the sigma antagonists BD1047 and BD1063, further confirming specificity as a receptor-mediated event. The transient rise in [Ca(2+)](i) occurred in the absence of extracellular Ca(2+) and was completely eliminated by pretreatment of cells with thapsigargin. Thus, sigma-2 receptors stimulate a transient release of Ca(2+) from the endoplasmic reticulum. Prolonged exposure of cells to sigma-receptor ligands resulted in a latent and sustained rise in [Ca(2+)](i), with a pharmacological profile identical to that of the transient rise. This sustained rise in [Ca(2+)](i) was affected by neither the removal of extracellular Ca(2+) nor thapsigargin pretreatment, suggesting latent sigma-2 receptor-induced release from thapsigargin-insensitive intracellular Ca(2+) stores. Sigma-2 receptors may use Ca(2+) signals in producing cellular effects.

  20. Targeting ligand-operated chaperone sigma-1 receptors in the treatment of neuropsychiatric disorders

    PubMed Central

    Teruo, Hayashi; Shang-Yi, Tsai; Tomohisa, Mori; Michiko, Fujimoto; Tsung-Ping, Su

    2011-01-01

    Introduction Current conventional therapeutic drugs for the treatment of psychiatric or neurodegenerative disorders have certain limitations of use. Psychotherapeutic drugs such as typical and atypical antipsychotics, tricyclic antidepressants, and selective monoamine reuptake inhibitors, aim to normalize the hyper- or hypo-neurotransmission of monoaminergic systems. Despite their great contribution to the outcomes of psychiatric patients, these agents often exert severe side effects and require chronic treatments to promote amelioration of symptoms. Furthermore, drugs available for the treatment of neurodegenerative disorders are severely limited. Areas covered This review discusses recent evidence that has shed light on sigma-1 receptor ligands, which may serve as a new class of antidepressants or neuroprotective agents. Sigma-1 receptors are novel ligand-operated molecular chaperones regulating a variety of signal transduction, ER stress, cellular redox, cellular survival, and synaptogenesis. Selective sigma-1 receptor ligands exert rapid antidepressant-like, anxiolytic, antinociceptive and robust neuroprotective actions in preclinical studies. The review also looks at recent studies which suggest that reactive oxygen species might play a crucial role as signal integrators at the downstream of Sig-1Rs Expert opinion The significant advances in sigma receptor research in the last decade have begun to elucidate the intracellular signal cascades upstream and downstream of sigma-1 receptors. The novel ligand-operated properties of the sigma-1 receptor chaperone may enable a variety of interventions by which stress-related cellular systems are pharmacologically controlled. PMID:21375464

  1. The Applicability of Lean and Six Sigma Techniques to Clinical and Translational Research

    PubMed Central

    Schweikhart, Sharon A.; Dembe, Allard E

    2010-01-01

    Background Lean and Six Sigma are business management strategies commonly used in production industries to improve process efficiency and quality. During the past decade, these process improvement techniques increasingly have been applied outside of the manufacturing sector, for example, in health care and in software development. This article concerns the potential use of Lean and Six Sigma to improve the processes involved in clinical and translational research. Improving quality, avoiding delays and errors, and speeding up the time to implementation of biomedical discoveries are prime objectives of the NIH Roadmap for Biomedical Research and the NIH Clinical and Translational Science Award (CTSA) program. Methods This article presents a description of the main principles, practices, and methodologies used in Lean and Six Sigma. Available literature involving applications of Lean and Six Sigma to health care, laboratory science, and clinical and translational research is reviewed. Specific issues concerning the use of these techniques in different phases of translational research are identified. Results Examples are provided of Lean and Six Sigma applications that are being planned at a current CTSA site, which could potentially be replicated elsewhere. We describe how different process improvement approaches are best adapted for particularly translational research phases. Conclusions Lean and Six Sigma process improvement methodologies are well suited to help achieve NIH’s goal of making clinical and translational research more efficient and cost-effective, enhancing the quality of the research, and facilitating the successful adoption of biomedical research findings into practice. PMID:19730130

  2. Characterization and Evaluation of Two Novel Fluorescent Sigma-2 Receptor Ligands as Proliferation Probes

    PubMed Central

    Zeng, Chenbo; Vangveravong, Suwanna; Jones, Lynne A.; Hyrc, Krzysztof; Chang, Katherine C.; Xu, Jinbin; Rothfuss, Justin M.; Goldberg, Mark P.; Hotchkiss, Richard S.; Mach, Robert H.

    2015-01-01

    We synthesized and characterized two novel fluorescent sigma-2 receptor selective ligands, SW120 and SW116, and evaluated these ligands as potential probes for imaging cell proliferation. Both ligands are highly selective for sigma-2 receptors versus sigma-1 receptors. SW120 and SW116 were internalized into MDA-MB-435 cells, and 50% of the maximum fluorescent intensity was reached in 11 and 24 minutes, respectively. In vitro studies showed that 50% of SW120 or SW116 washed out of cells in 1 hour. The internalization of SW120 was reduced ≈30% by phenylarsine oxide, an inhibitor of endocytosis, suggesting that sigma-2 ligands are internalized, in part, by an endocytotic pathway. Subcellular localization studies using confocal and two-photon microscopy showed that SW120 and SW116 partially colocalized with fluorescent markers of mitochondria, endoplasmic reticulum, lysosomes, and the plasma membrane, suggesting that sigma-2 receptors localized to the cytoplasmic organelles and plasma membrane. SW120 did not colocalize with the nuclear dye 4′,6-diamidino-2-phenylindole. In vivo studies showed that the uptake of SW120 in solid tumors and peripheral blood mononuclear cells of mice positively correlated with the expression level of the cell proliferation marker Ki-67, suggesting that sigma-2 fluorescent probes may be used to image cell proliferation in mice. PMID:22201533

  3. GLOBAL STAR FORMATION REVISITED

    SciTech Connect

    Silk, Joseph; Norman, Colin E-mail: norman@stsci.edu

    2009-07-20

    A general treatment of disk star formation is developed from a dissipative multiphase model, with the dominant dissipation due to cloud collisions. The Schmidt-Kennicutt (SK) law emerges naturally for star-forming disks and starbursts. We predict that there should be an inverse correlation between Tully-Fisher law and SK law residuals. The model is extended to include a multiphase treatment of supernova feedback that leads to a turbulent pressure-regulated generalization of the star formation law and is applicable to gas-rich starbursts. Enhanced pressure, as expected in merger-induced star formation, enhances star formation efficiency. An upper limit is derived for the disk star formation rate in starbursts that depends on the ratio of global ISM to cloud pressures. We extend these considerations to the case where the interstellar gas pressure in the inner galaxy is dominated by outflows from a central active galactic nucleus (AGN). During massive spheroid formation, AGN-driven winds trigger star formation, resulting in enhanced supernova feedback and outflows. The outflows are comparable to the AGN-boosted star formation rate and saturate in the super-Eddington limit. Downsizing of both SMBH and spheroids is a consequence of AGN-driven positive feedback. Bondi accretion feeds the central black hole with a specific accretion rate that is proportional to the black hole mass. AGN-enhanced star formation is mediated by turbulent pressure and relates spheroid star formation rate to black hole accretion rate. The relation between black hole mass and spheroid velocity dispersion has a coefficient (Salpeter time to gas consumption time ratio) that provides an arrow of time. Highly efficient, AGN-boosted star formation can occur at high redshift.

  4. The Pistol Star

    NASA Astrophysics Data System (ADS)

    Figer, Donald F.; Najarro, Francisco; Morris, Mark; McLean, Ian S.; Geballe, Thomas R.; Ghez, Andrea M.; Langer, Norbert

    1998-10-01

    We present new near-infrared data and analysis, which indicate that the Pistol Star is one of the most luminous stars known, adding another test point for massive star formation and stellar evolution theories. We estimate an extinction of AK = 3.2 +/- 0.5 using the near-infrared colors of the star and of surrounding stars in the young Quintuplet cluster. Using our wind/atmosphere code, we find two families of models that fit the spectral energy distribution and detailed line profiles. The lower luminosity models give L = 106.6+/-0.2 L⊙ and Teff = 104.15+/-0.01 K, while the higher luminosity models give L = 107.2+/-0.2 L⊙ and Teff = 104.33+/-0.01 K; the error in luminosity assumes an uncertainty of +/-0.5 in AK, while the error in Teff is constrained by detailed line modeling. The models also reveal a helium enriched surface. As previously existing stellar evolution models do not extend to such high luminosities, we employ new evolutionary tracks for very massive stars to determine the initial mass and age of the Pistol Star, and estimate Minitial = 200-250 M⊙ and an age of 1.7-2.1 Myr. The inferred luminosity and temperature place the star in a sparsely populated zone in the H-R diagram where luminous blue variables (LBVs) are often found. This is consistent with our evolutionary models, which predict that the star is in an unstable evolutionary stage. We interpret the star and its surrounding nebula as an LBV that has recently ejected large amounts of material. Our K-band speckle-imaging data reveal the star to be single down to a projected separation of 110 AU.

  5. VARIABLE STARS IN THE ULTRA-FAINT DWARF SPHEROIDAL GALAXY URSA MAJOR I

    SciTech Connect

    Garofalo, Alessia; Moretti, Maria Ida; Cusano, Felice; Clementini, Gisella; Ripepi, Vincenzo; Dall'Ora, Massimo; Coppola, Giuseppina; Musella, Ilaria; Marconi, Marcella E-mail: fcusano@na.astro.it E-mail: ripepi@na.astro.it E-mail: imoretti@na.astro.it E-mail: ilaria@na.astro.it

    2013-04-10

    We have performed the first study of the variable star population of Ursa Major I (UMa I), an ultra-faint dwarf satellite recently discovered around the Milky Way (MW) by the Sloan Digital Sky Survey. Combining time series observations in the B and V bands from four different telescopes, we have identified seven RR Lyrae stars in UMa I, of which five are fundamental-mode (RRab) and two are first-overtone pulsators (RRc). Our V, B - V color-magnitude diagram of UMa I reaches V {approx} 23 mag (at a signal-to-noise ratio of {approx}6) and shows features typical of a single old stellar population. The mean pulsation period of the RRab stars (P{sub ab}) = 0.628, {sigma} = 0.071 days (or (P{sub ab}) = 0.599, {sigma} = 0.032 days, if V4, the longest period and brightest variable, is discarded) and the position on the period-amplitude diagram suggest an Oosterhoff-intermediate classification for the galaxy. The RR Lyrae stars trace the galaxy horizontal branch (HB) at an average apparent magnitude of (V(RR)) = 20.43 {+-} 0.02 mag (average on six stars and discarding V4), giving in turn a distance modulus for UMa I of (m - M){sub 0} = 19.94 {+-} 0.13 mag, distance d = 97.3{sup +6.0}{sub -5.7} kpc, in the scale where the distance modulus of the Large Magellanic Cloud is 18.5 {+-} 0.1 mag. Isodensity contours of UMa I red giants and HB stars (including the RR Lyrae stars identified in this study) show that the galaxy has an S-shaped structure, which is likely caused by the tidal interaction with the MW. Photometric metallicities were derived for six of the UMa I RR Lyrae stars from the parameters of the Fourier decomposition of the V-band light curves, leading to an average metal abundance of [Fe/H] = -2.29 dex ({sigma} = 0.06 dex, average on six stars) on the Carretta et al. metallicity scale.

  6. PRECISION PHOTOMETRIC MONITORING OF VERY LOW MASS {sigma} ORIONIS CLUSTER MEMBERS: VARIABILITY AND ROTATION AT A FEW Myr

    SciTech Connect

    Cody, Ann Marie; Hillenbrand, Lynne A.

    2010-12-15

    We present high-precision photometry on 107 variable low-mass stars and brown dwarfs in the {approx}3 Myr {sigma} Orionis open cluster. We have carried out I-band photometric monitoring within two fields, encompassing 153 confirmed or candidate members of the low-mass cluster population, from 0.02 to 0.5 M {sub sun}. We are sensitive to brightness changes on timescales from 10 minutes to two weeks with amplitudes as low as 0.004 mag, and find variability on these timescales in nearly 70% of cluster members. We identify both periodic and aperiodic modes of variability, as well as semi-periodic rapid fading events that are not accounted for by the standard explanations of rotational modulation of surface features or accretion. We have incorporated both optical and infrared color data to uncover trends in variability with mass and circumstellar disks. While the data confirm that the lowest-mass objects (M < 0.2 M {sub sun}) rotate more rapidly than the 0.2-0.5 M {sub sun} members, they do not support a direct connection between rotation rate and the presence of a disk. Finally, we speculate on the origin of irregular variability in cluster members with no evidence for disks or accretion.

  7. Star Trek in the Schools

    ERIC Educational Resources Information Center

    Journal of Aerospace Education, 1977

    1977-01-01

    Describes specific educational programs for using the Star Trek TV program from kindergarten through college. For each grade level lesson plans, ideas for incorporating Star Trek into future classes, and reports of specific programs utilizing Star Trek are provided. (SL)

  8. Observations of FK Comae stars

    NASA Technical Reports Server (NTRS)

    Bopp, B. W.

    1981-01-01

    Observations on the FK Comae stars are described. FK Com, UZ Lib and HD 199178 are compared and related as a group of stars. The crucial observational tests of the proposed evolutionary status of these stars are noted.

  9. Neutron Star Compared to Manhattan

    NASA Video Gallery

    A pulsar is a neutron star, the crushed core of a star that has exploded. Neutron stars crush half a million times more mass than Earth into a sphere no larger than Manhattan, as animated in this s...

  10. Stars and Flowers, Flowers and Stars

    NASA Astrophysics Data System (ADS)

    Minti, Hari

    2012-12-01

    The author, a graduated from the Bucharest University (1964), actually living and working in Israel, concerns his book to variable stars and flowers, two domains of his interest. The analogies includes double stars, eclipsing double stars, eclipses, Big Bang. The book contains 34 chapters, each of which concerns various relations between astronomy and other sciences and pseudosciences such as Psychology, Religion, Geology, Computers and Astrology (to which the author is not an adherent). A special part of the book is dedicated to archeoastronomy and ethnoastronomy, as well as to history of astronomy. Between the main points of interest of these parts: ancient sanctuaries in Sarmizegetusa (Dacia), Stone Henge(UK) and other. The last chapter of the book is dedicated to flowers. The book is richly illustrated. It is designed for a wide circle of readers.

  11. Populations of Carbon Stars

    NASA Astrophysics Data System (ADS)

    Lloyd Evans, T.

    2011-09-01

    Carbon stars in the Galaxy do not constitute a single family, but may be divided over several types with distinctive spectroscopic and photometric properties. A subtype of the N stars, characterised by high velocities and weak CN bands, may have been captured by the Milky Way from a cannibalised dwarf galaxy.

  12. Modeling rapidly rotating stars

    NASA Astrophysics Data System (ADS)

    Rieutord, M.

    2006-06-01

    We review the quest of modeling rapidly rotating stars during the past 40 years and detail the challenges to be taken up by models facing new data from interferometry, seismology, spectroscopy... We then present the progress of the ESTER project aimed at giving a physically self-consistent model for the structure and evolution of rapidly rotating stars.

  13. Science through ARts (STAR)

    ERIC Educational Resources Information Center

    Densmore, Marycay; Kolecki, Joseph C.; Miller, Allan; Petersen, Ruth; Terrell, Mike

    2005-01-01

    Science Through ARts (STAR) is a free, international, cross-curricular program thematically aligned with "The Vision for Space Exploration," a framework of goals and objectives published by NASA in February 2004. Through the STAR program, students in grades 5 through 12 are encouraged to apply their knowledge in creative ways as they approach a…

  14. Observing Double Stars

    NASA Astrophysics Data System (ADS)

    Genet, Russell M.; Fulton, B. J.; Bianco, Federica B.; Martinez, John; Baxter, John; Brewer, Mark; Carro, Joseph; Collins, Sarah; Estrada, Chris; Johnson, Jolyon; Salam, Akash; Wallen, Vera; Warren, Naomi; Smith, Thomas C.; Armstrong, James D.; McGaughey, Steve; Pye, John; Mohanan, Kakkala; Church, Rebecca

    2012-05-01

    Double stars have been systematically observed since William Herschel initiated his program in 1779. In 1803 he reported that, to his surprise, many of the systems he had been observing for a quarter century were gravitationally bound binary stars. In 1830 the first binary orbital solution was obtained, leading eventually to the determination of stellar masses. Double star observations have been a prolific field, with observations and discoveries - often made by students and amateurs - routinely published in a number of specialized journals such as the Journal of Double Star Observations. All published double star observations from Herschel's to the present have been incorporated in the Washington Double Star Catalog. In addition to reviewing the history of visual double stars, we discuss four observational technologies and illustrate these with our own observational results from both California and Hawaii on telescopes ranging from small SCTs to the 2-meter Faulkes Telescope North on Haleakala. Two of these technologies are visual observations aimed primarily at published "hands-on" student science education, and CCD observations of both bright and very faint doubles. The other two are recent technologies that have launched a double star renaissance. These are lucky imaging and speckle interferometry, both of which can use electron-multiplying CCD cameras to allow short (30 ms or less) exposures that are read out at high speed with very low noise. Analysis of thousands of high speed exposures allows normal seeing limitations to be overcome so very close doubles can be accurately measured.

  15. Party with the Stars.

    ERIC Educational Resources Information Center

    Blaine, Lloyd

    1997-01-01

    Describes a Star Party which involves comparing the different colors of the stars, demonstrating how astronomers measure the sky with degrees, determining the cardinal direction, discussing numerous stories that ancient civilizations gave to constellations, exercising science process skills, and using science instruments. (JRH)

  16. Science Through ARts (STAR)

    NASA Technical Reports Server (NTRS)

    Kolecki, Joseph; Petersen, Ruth; Williams, Lawrence

    2002-01-01

    Science Through ARts (STAR) is an educational initiative designed to teach students through a multidisciplinary approach to learning. This presentation describes the STAR pilot project, which will use Mars exploration as the topic to be integrated. Schools from the United Kingdom, Japan, the United States, and possibly eastern Europe are expected to participate in the pilot project.

  17. 'Marginal' BY Draconis stars

    NASA Technical Reports Server (NTRS)

    Bopp, Bernard W.

    1987-01-01

    Spectroscopic observations of 52 dK-dM stars, obtained at 640-665 nm (with spectral resolution 70-90 pm) using CCD detectors on the coude-feed telescope at KPNO since 1982, are reported. Data for four stars found to have diluted absorption or weak emission above continuum at H-alpha are presented in tables and spectra and discussed in detail. These objects (Gliese numbers 256, 425A, 900, and 907.1) are shown to be 'marginal' BY Dra stars, single objects of age 2.5-3 Gyr with activity and rotational velocity (3-5 km/s) between those of normal dM stars and those of true BY Dra stars. An explanation based on evolution from the BY Dra stage through marginal BY Dra to inactive dM is proposed.

  18. Producing Runaway Stars

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-07-01

    How are the hypervelocity stars weve observed in our galaxy produced? A recent study suggests that these escapees could be accelerated by a massive black hole in the center of the Large Magellanic Cloud.A Black Hole SlingshotSince their discovery in 2005, weve observed dozens of candidate hypervelocity stars stars whose velocity in the rest frame of our galaxy exceeds the local escape velocity of the Milky Way. These stars present a huge puzzle: how did they attain these enormous velocities?One potential explanation is known as the Hills mechanism. In this process, a stellar binary is disrupted by a close encounter with a massive black hole (like those thought to reside at the center of every galaxy). One member of the binary is flung out of the system as a result of the close encounter, potentially reaching very large velocities.A star-forming region known as LHA 120-N 11, located within the LMC. Some binary star systems within the LMC might experience close encounters with a possible massive black hole at the LMCs center. [ESA/NASA/Hubble]Blame the LMC?Usually, discussions of the Hills mechanism assume that Sagittarius A*, the supermassive black hole at the center of the Milky Way, is the object guilty of accelerating the hypervelocity stars weve observed. But what if the culprit isnt Sgr A*, but a massive black hole at the center of the Large Magellanic Cloud (LMC), one of the Milky Ways satellite galaxies?Though we dont yet have evidence of a massive black hole at the center of the LMC, the dwarf galaxy is large enough to potentially host one as large as 100,000 solar masses. Assuming that it does, two scientists at the University of Cambridge, Douglas Boubert and Wyn Evans, have now modeled how this black hole might tear apart binary star systems and fling hypervelocity stars around the Milky Way.Models for AccelerationBoubert and Evans determined that the LMCs hypothetical black hole could easily eject stars at ~100 km/s, which is the escape velocity of the

  19. Abundances in Sagittarius Stars

    NASA Astrophysics Data System (ADS)

    Bonifacio, P.; Zaggia, S.; Sbordone, L.; Santin, P.; Monaco, L.; Monai, S.; Molaro, P.; Marconi, G.; Girardi, L.; Ferraro, F.; di Marcantonio, P.; Caffau, E.; Bellazzini, M.

    The Sagittarius dwarf spheroidal is a very complex galaxy, which has undergone prolonged star formation. From the very first high resolution chemical analysis of Sgr stars, conducted using spectra obtained during the commissioning of UVES at VLT, it was clear that the star had undergone a high level of chemical processing, at variance with most of the other Local Group dwarf spheroidals. Thanks to FLAMES at VLT we now have accurate metallicities and abundances of alpha-chain elements for about 150 stars, which provide the first reliable metallicity distribution for this galaxy. Besides the already known high metallicity tail the existence of a metal-poor population has also been highlighted, although an assessment of the fraction of Sgr stars which belong to this population requires a larger sample. From our data it is also obvious that Sagittarius is a nucleated galaxy and that the centre of the nucleus coincides with M54, as already shown by Monaco et al.

  20. A microwave survey of southern early-type stars

    NASA Astrophysics Data System (ADS)

    Slee, O. B.; Budding, E.

    1995-12-01

    A multi-epoch survey with the Parkes telescope of a complete distance-limited sample of 57 stars earlier than F6 has detected possible 8.4-GHz emission from 16 stars. Single-epoch partial synthesis observations with the Australia Telescope Compact Array (ATCA) at 4.8 GHz on 27 stars from the same sample (including the possible Parkes detections) found no emission at the stellar positions above a flux density limit of 1.2-1.9 mJy, but the maps show that the Parkes detections are not merely the results of confusion of sources within the Parkes beam. Three early F stars with UV and/or X-ray emission were observed simultaneously at 4.8 and 8.4 GHz in 12-h syntheses with the 6-element ATCA. Two of these stars were from the above sample and the third was the supergiant Alpha Carinae. We detected only alphaCar with flux densities of 300+/-65 and 140+/-65 muJy at 4.8 and 8.6 GHz (S~nu^-1.3+/-1.3). We discuss the legitimacy of the Parkes 3-6sigma detections and show that, although none has been detected by synthesis observations, there is no compelling reason for rejecting them on the internal evidence. The power emitted by the supergiant alphaCar is similar to that of the 16 possible Parkes detections, although its activity index is orders of magnitude lower. We show that this emission cannot be thermal bremsstrahlung from the 10^7.2-K corona of the star but is probably synchrotron emission from a magnetically maintained corona.

  1. VizieR Online Data Catalog: Motion Verified Red Stars (MoVeRS) (Theissen+, 2016)

    NASA Astrophysics Data System (ADS)

    Theissen, C. A.; West, A. A.; Dhital, S.

    2015-09-01

    We present a photometric catalog of 8,735,004 proper motion selected low-mass stars (KML-spectral types) within the Sloan Digital Sky Survey (SDSS) footprint, from the combined SDSS-DR10, Two-Micron All-Sky Survey (2MASS) Point Source Catalog (PSC), and Wide-field Infrared Survey Explorer (WISE) AllWISE catalog. Stars were selected using r-i, i-z, r-z, z-J, and z-W1 colors, and SDSS, WISE, and 2MASS astrometry was combined to compute proper motions. The resulting 3,518,150 stars were augmented with proper motions for 5,216,854 earlier type stars from the combined SDSS and United States Naval Observatory B1.0 catalog (USNO-B). We used SDSS+USNO-B proper motions to determine the best criteria for selecting a clean sample of stars. Only stars whose proper motions were greater than their 2-sigma uncertainty were included. Our Motion Verified Red Stars (MoVeRS) catalog is available through SDSS CasJobs and VizieR. (2 data files).

  2. The origin of aromaticity: important role of the sigma framework in benzene.

    PubMed

    Kovacević, Borislav; Barić, Danijela; Maksić, Zvonimir B; Müller, Thomas

    2004-09-20

    The physical nature of aromaticity is addressed at a high ab initio level. It is conclusively shown that the extrinsic aromatic stabilization energy of benzene E(ease)B, estimated relative to its linear polyene counterpart(s), is very well-reproduced at the Hartree-Fock (HF) level. This is a consequence of the fact that the contributions arising from the zero-point vibrational energy (ZPVE) and electron correlation are rather small. More specifically, they yield together 2.0 kcalmol(-1) to the destabilization of benzene. A careful scrutiny of the HF energies by virial theorem shows further that the kinetic energies of the sigma and pi electrons E(T)HF(sigma) and E(T)HF(pi) are strictly additive in the gauge linear zig-zag polyenes, which also holds for their sum Et(T)HF This finding has the important corollary that E(ease)B is little dependent on the choice of the homodesmic reactions involving zig-zag polyenes. A detailed physical analysis of the sigma- and pi-electron contributions to extrinsic aromaticity requires explicit introduction of the potential energy terms Vne, Vee, and Vnn, which signify Coulomb interactions between the electrons and the nuclei. The Vee term involves repulsive interaction Vee(sigmapi) between the sigma and pi electrons, which cannot be unequivocally resolved into sigma and pi contributions. The same holds for the Vnn energy, which implicitly depends on the electron density distribution via the Born-Oppenheimer (BO) potential energy surface. Several possibilities for partitioning Vee(sigmapi) and Vnn terms into sigma and pi components are examined. It is argued that the stockholder principle is the most realistic, which strongly indicates that E(ease)B is a result of favorable sigma-framework interactions. In contrast, the pi-electron framework prefers the open-chain linear polyenes.

  3. Antitussive activity of sigma-1 receptor agonists in the guinea-pig.

    PubMed

    Brown, Claire; Fezoui, Malika; Selig, William M; Schwartz, Carl E; Ellis, James L

    2004-01-01

    1. Current antitussive medications have limited efficacy and often contain the opiate-like agent dextromethorphan (DEX). The mechanism whereby DEX inhibits cough is ill defined. DEX displays affinity at both NMDA and sigma receptors, suggesting that the antitussive activity may involve central or peripheral activity at either of these receptors. This study examined and compared the antitussive activity of DEX and various putative sigma receptor agonists in the guinea-pig citric-acid cough model. 2. Intraperitoneal (i.p.) administration of DEX (30 mg kg(-1)) and the sigma-1 agonists SKF-10,047 (1-5 mg kg(-1)), Pre-084 (5 mg kg(-1)), and carbetapentane (1-5 mg kg(-1)) inhibited citric-acid-induced cough in guinea-pigs. Intraperitoneal administration of a sigma-1 antagonist, BD 1047 (1-5 mg kg(-1)), reversed the inhibition of cough elicited by SKF-10,047. In addition, two structurally dissimilar sigma agonists SKF-10,047 (1 mg ml(-1)) and Pre-084 (1 mg ml(-1)) inhibited cough when administered by aerosol. 3. Aerosolized BD 1047 (1 mg ml(-1), 30 min) prevented the antitussive action of SKF-10,047 (5 mg kg(-1)) or DEX (30 mg kg(-1)) given by i.p. administration and, likewise, i.p. administration of BD 1047 (5 mg kg(-1)) prevented the antitussive action of SKF-10,047 given by aerosol (1 mg ml(-1)). 4. These results therefore support the argument that antitussive effects of DEX may be mediated via sigma receptors, since both systemic and aerosol administration of sigma-1 receptor agonists inhibit citric-acid-induced cough in guinea-pigs. While significant systemic exposure is possible with aerosol administration, the very low doses administered (estimated <0.3 mg kg(-1)) suggest that there may be a peripheral component to the antitussive effect.

  4. The origin of aromaticity: important role of the sigma framework in benzene.

    PubMed

    Kovacević, Borislav; Barić, Danijela; Maksić, Zvonimir B; Müller, Thomas

    2004-09-20

    The physical nature of aromaticity is addressed at a high ab initio level. It is conclusively shown that the extrinsic aromatic stabilization energy of benzene E(ease)B, estimated relative to its linear polyene counterpart(s), is very well-reproduced at the Hartree-Fock (HF) level. This is a consequence of the fact that the contributions arising from the zero-point vibrational energy (ZPVE) and electron correlation are rather small. More specifically, they yield together 2.0 kcalmol(-1) to the destabilization of benzene. A careful scrutiny of the HF energies by virial theorem shows further that the kinetic energies of the sigma and pi electrons E(T)HF(sigma) and E(T)HF(pi) are strictly additive in the gauge linear zig-zag polyenes, which also holds for their sum Et(T)HF This finding has the important corollary that E(ease)B is little dependent on the choice of the homodesmic reactions involving zig-zag polyenes. A detailed physical analysis of the sigma- and pi-electron contributions to extrinsic aromaticity requires explicit introduction of the potential energy terms Vne, Vee, and Vnn, which signify Coulomb interactions between the electrons and the nuclei. The Vee term involves repulsive interaction Vee(sigmapi) between the sigma and pi electrons, which cannot be unequivocally resolved into sigma and pi contributions. The same holds for the Vnn energy, which implicitly depends on the electron density distribution via the Born-Oppenheimer (BO) potential energy surface. Several possibilities for partitioning Vee(sigmapi) and Vnn terms into sigma and pi components are examined. It is argued that the stockholder principle is the most realistic, which strongly indicates that E(ease)B is a result of favorable sigma-framework interactions. In contrast, the pi-electron framework prefers the open-chain linear polyenes. PMID:15503393

  5. Pharmacological comparison of antipsychotic drugs and sigma-antagonists in rodents.

    PubMed

    Lang, A; Soosaar, A; Kõks, S; Volke, V; Bourin, M; Bradwejn, J; Vasar, E

    1994-01-01

    We compared antipsychotic drugs (haloperidol, chlorpromazine and clozapine) and sigma antagonists (remoxipride, cinuperone, alpha-(4-fluorophenyl)-4-(-fluoro-2-pyrimidinyl)-1-piperazine butanol (BMY 14802) and rimcazole) in the radio-ligand binding and behavioural experiments in rodents. A good correlation was established between the affinity of compounds at dopamine2-receptors in the striatum and their ability to block apomorphine-, amphetamine- and quipazine-induced behavioural effects in rodents. By contrast, no correlation was found between the behavioural effects of these drugs and their affinity at dopamine1-5-HT2- and sigma receptors. The rank order of potency among the studied antipsychotic drugs in the behavioural tests and at dopamine2-receptors was following: haloperidol > chlorpromazine > or = clozapine. The effectiveness of chlorpromazine and clozapine was nearly similar against apomorphine-induced aggressiveness and yawning, whereas at 5-HT2-receptors clozapine was more active than chlorpromazine. The weak activity of sigma antagonists at dopamine2 receptors could be a possible reason why these compounds were less effective in the behavioural studies compared to antipsychotic drugs. However, the antagonism of remoxipride against apomorphine-induced stereotypy and aggressiveness is not related to its activity at sigma receptors, because the other sigma antagonists did not block these effects of apomorphine. It is probable that remoxipride exerts its action through blocking of dopamine2 receptors. In conclusion, the present study revealed only weak activity of sigma antagonists in the behavioural models widely used to study the antipsychotic drugs. Therefore, the antipsychotic activity of sigma antagonists is doubtful.

  6. Radial velocities of very low mass stars and candidate brown dwarf members of the Hyades and Pleiades

    NASA Technical Reports Server (NTRS)

    Stauffer, John R.; Liebert, James; Giampapa, Mark; Macintosh, Bruce; Reid, Neill; Hamilton, Donald

    1994-01-01

    We have determined H alpha equivalent widths and radial velocities with 1 sigma accuracies of approximately 5 km s(exp -1) for approximately 20 candidate very low mass members of the Hyades and Pleiades clusters. The radial velocities for the Hyades sample suggest that nearly all of these stars are indeed highly probable members of the Hyades. The faintest stars in the Hyades sample have masses of order 0.1 solar mass. We also obtained radial velocities for four candidate very low mass members of the Pleiades and two objects that are candidate BD Pleiads. All of these stars have apparent V magnitudes fainter than the Hyades stars we observed, and the resultant radial velocity accuracy is worse. We believe that the three brighter stars are indeed likely very low mass stellar members of the Pleiades, whereas the status of the two brown dwarf candidates is uncertain. The Hyades stars we have observed and the three Pleiades very low mass stars are the lowest mass members of any open cluster whose membership has been confirmed by radial velocities and whose chromospheric activity has been measured. We see no change in chromospheric activity at the boundary where stars are expected to become fully convective (M approximately equals 0.3 solar mass) in either cluster. In the Pleiades, however, there may be a decrease in chromospheric activity for stars with (V-I)(sub K) greater than 3.5 (M less than or equal to 0.1 solar mass).

  7. Modeling the magnetospheres of luminous stars: Interactions between supersonic radiation-driven winds and stellar magnetic fields

    SciTech Connect

    Owocki, Stan; Townsend, Rich; Ud-Doula, Asif

    2007-05-15

    Hot, luminous stars (spectral types O and B) lack the hydrogen recombination convection zones that drive magnetic dynamo generation in the sun and other cool stars. Nonetheless, observed rotational modulation of spectral lines formed in the strong, radiatively driven winds of hot stars suggests magnetic perturbations analogous to those that induce 'co-rotating interaction regions' in the solar wind. Indeed, recent advances in spectropolarimetric techniques have now led to direct detection of moderate to strong (100-10 000 G), tilted dipole magnetic fields in several hot stars. Using a combination of analytic and numerical magnetohydrodynamic models, this paper focuses on the role of such magnetic fields in channeling, and sometimes confining, the radiatively driven mass outflows from such stars. The results show how 'magnetically confined wind shocks' can explain the moderately hard x-ray emission seen from the O7V star Theta-1 Ori C, and how the trapping of material in a 'rigidly rotating magnetosphere' can explain the periodically modulated Balmer line emission seen from the magnetic B2pV star Sigma Ori E. In addition, magnetic reconnection heating from episodic centrifugal breakout events might explain the occasional very hard x-ray flares seen from the latter star. The paper concludes with a brief discussion on the generation of hot-star fields and the broader relationship to other types of magnetospheres.

  8. Catch a Star!

    NASA Astrophysics Data System (ADS)

    2006-11-01

    ESO and the European Association for Astronomy Education are launching today the 2007 edition of 'Catch a Star!', their international astronomy competition for school students. Now in its fifth year, the competition offers students the chance to win a once-in-a-lifetime trip to ESO's flagship observatory in Chile, as well as many other prizes. Students are invited to 'become astronomers' and embark on a journey to explore the Universe. ESO PR Photo 42/06 The competition includes separate categories - 'Catch a Star Researchers' and 'Catch a Star Adventurers' - to ensure that every student, whatever their level, has the chance to enter and win exciting prizes. For the artistically minded, 'Catch a Star!' also includes an artwork competition, 'Catch a Star Artists'. "'Catch a Star!' offers a unique opportunity for students to learn more about astronomy and about the methods scientists use to discover new things about the Universe", said Douglas Pierce-Price, Education Officer at ESO. In teams, students choose an astronomical topic to study and produce an in-depth report. An important part of the project for 'Catch a Star Researchers' is to think about how ESO's telescopes or a telescope of the future can contribute to their investigations of the subject. As well as the top prize - a trip to one of ESO's observatory sites in Chile - visits to observatories in Germany, Austria and Spain, and many other prizes are also available to be won. 'Catch a Star Researchers' winners will be chosen by an international jury, and 'Catch a Star Adventurers' will be awarded further prizes by lottery. Entries for 'Catch a Star Artists' will be displayed on the web and winners chosen with the help of a public online vote. The first editions of 'Catch a Star!' have attracted several hundred entries from more than 25 countries worldwide. Previous winning entries have included "Star clusters and the structure of the Milky Way" (Budapest, Hungary), "Vega" (Acqui Terme, Italy) and "Venus

  9. Making star teams out of star players.

    PubMed

    Mankins, Michael; Bird, Alan; Root, James

    2013-01-01

    Top talent is an invaluable asset: In highly specialized or creative work, for instance, "A" players are likely to be six times as productive as "B" players. So when your company has a crucial strategic project, why not multiply all that firepower and have a team of your best performers tackle it? Yet many companies hesitate to do this, believing that all-star teams don't work: Big egos will get in the way. The stars won't be able to work with one another. They'll drive the team Leader crazy. Mankins, Bird, and Root of Bain & Company believe it's time to set aside that thinking. They have seen all-star teams do extraordinary work. But there is a right way and a wrong way to organize them. Before you can even begin to assemble such a team, you need to have the right talent management practices, so you hire and develop the best people and know what they're capable of. You have to give the team appropriate incentives and leaders and support staffers who are stars in their own right. And projects that are ill-defined or small scale are not for all-star teams. Use them only for critical missions, and make sure their objectives are clear. Even with the right setup, things can still go wrong. The wise executive will take steps to manage egos, prune non-team-players, and prevent average coworkers from feeling completely undervalued. She will also invest a lot of time in choosing the right team Leader and will ask members for lots of feedback to monitor how that leader is doing. PMID:23390743

  10. Pseudosynchronization of Heartbeat Stars

    NASA Astrophysics Data System (ADS)

    Zimmerman, Mara; Thompson, Susan E.; Hambleton, Kelly; Fuller, Jim; Shporer, Avi; Isaacson, Howard T.; Howard, Andrew; Kurtz, Donald

    2016-01-01

    A type of eccentric binary star that undergoes extreme dynamic tidal forces, known as Heartbeat stars, were discovered by the Kepler Mission. As the two stars pass through periastron, the tidal distortion causes unique brightness variations. Short period, eccentric binary stars, like these, are theorized to pseudosynchronize, or reach a rotational frequency that matches the weighted average orbital angular velocity of the system. This pseudosynchronous rate, as predicted by Hut (1981), depends on the binary's orbital period and eccentricity. We tested whether sixteen heartbeat stars have pseudosynchronized. We measure the rotation rate from obvious spot signatures in the light curve. We measure the eccentricity by fitting the light curve using PHOEBE and are actively carrying out a radial velocity monitoring program with Keck/HIRES in order to improve these orbital parameters. Our initial results show that while most heartbeat stars appear to have pseudosynchronized we find stars with rotation frequencies both longer and shorter than this rate. We thank the SETI Institute REU program, the NSF, and the Kepler Guest Observer Program for making this work possible.

  11. Dense Axion Stars

    NASA Astrophysics Data System (ADS)

    Mohapatra, Abhishek; Braaten, Eric; Zhang, Hong

    2016-03-01

    If the dark matter consists of axions, gravity can cause them to coalesce into axion stars, which are stable gravitationally bound Bose-Einstein condensates of axions. In the previously known axion stars, gravity and the attractive force between pairs of axions are balanced by the kinetic pressure. If the axion mass energy is mc2 =10-4 eV, these dilute axion stars have a maximum mass of about 10-14M⊙ . We point out that there are also dense axion stars in which gravity is balanced by the mean-field pressure of the axion condensate. We study axion stars using the leading term in a systematically improvable approximation to the effective potential of the nonrelativistic effective field theory for axions. Using the Thomas-Fermi approximation in which the kinetic pressure is neglected, we find a sequence of new branches of axion stars in which gravity is balanced by the mean-field interaction energy of the axion condensate. If mc2 =10-4 4 eV, the first branch of these dense axion stars has mass ranging from about 10-11M⊙ toabout M⊙.

  12. DISSECTING THE STELLAR-MASS-SFR CORRELATION IN z = 1 STAR-FORMING DISK GALAXIES

    SciTech Connect

    Salmi, F.; Daddi, E.; Elbaz, D.; Sargent, M. T.; Bethermin, M.; Renzini, A.; Le Borgne, D. E-mail: edaddi@cea.fr

    2012-07-20

    Using a mass-limited sample of 24 {mu}m detected, star-forming galaxies at 0.5 < z < 1.3, we study the mass-star formation rate (SFR) correlation and its tightness. The correlation is well defined ({sigma} = 0.28 dex) for disk galaxies (n{sub Sersic} < 1.5), while more bulge-dominated objects often have lower specific SFRs (sSFRs). For disk galaxies, a much tighter correlation ({sigma} = 0.19 dex) is obtained if the rest-frame H-band luminosity is used instead of stellar mass derived from multi-color photometry. The sSFR correlates strongly with rest-frame optical colors (hence luminosity-weighted stellar age) and also with clumpiness (which likely reflects the molecular gas fraction). This implies that most of the observed scatter is real, despite its low level, and not dominated by random measurement errors. After correcting for these differential effects a remarkably small dispersion remains ({sigma} = 0.14 dex), suggesting that measurement errors in mass or SFR are {approx}< 0.10 dex, excluding systematic uncertainties. Measurement errors in stellar masses, the thickening of the correlation due to real sSFR variations, and varying completeness with stellar mass, can spuriously bias the derived slope to lower values due to the finite range over which observables (mass and SFR) are available. When accounting for these effects, the intrinsic slope for the main sequence for disk galaxies gets closer to unity.

  13. STARs in the CNS.

    PubMed

    Ehrmann, Ingrid; Fort, Philippe; Elliott, David J

    2016-08-15

    STAR (signal transduction and activation of RNA) proteins regulate splicing of target genes that have roles in neural connectivity, survival and myelination in the vertebrate nervous system. These regulated splicing targets include mRNAs such as the Neurexins (Nrxn), SMN2 (survival of motor neuron) and MAG (myelin-associated glycoprotein). Recent work has made it possible to identify and validate STAR protein splicing targets in vivo by using genetically modified mouse models. In this review, we will discuss the importance of STAR protein splicing targets in the CNS (central nervous system). PMID:27528753

  14. Strange nonchaotic stars.

    PubMed

    Lindner, John F; Kohar, Vivek; Kia, Behnam; Hippke, Michael; Learned, John G; Ditto, William L

    2015-02-01

    The unprecedented light curves of the Kepler space telescope document how the brightness of some stars pulsates at primary and secondary frequencies whose ratios are near the golden mean, the most irrational number. A nonlinear dynamical system driven by an irrational ratio of frequencies generically exhibits a strange but nonchaotic attractor. For Kepler's "golden" stars, we present evidence of the first observation of strange nonchaotic dynamics in nature outside the laboratory. This discovery could aid the classification and detailed modeling of variable stars. PMID:25699444

  15. Mariner 9 star photography.

    NASA Technical Reports Server (NTRS)

    Thorpe, T. E.

    1973-01-01

    Mariner 9 achieved successful photography of the stars, the purpose of the experiment being to measure camera parameters associated with point source photometry, and to examine the feasibility of using stars as invariant calibration sources and a reference for optical navigation. The Mariner 9 camera-B photography demonstrated photometric response consistency over a limited sample of data to better than 15%. Camera performance verified the ability to model vidicon response characteristics as well as demonstrated an imaging capability sufficient to permit the use of stars for photometric calibration.

  16. A New Variable Star Search Program at the Rothney Astrophysical Observatory

    NASA Astrophysics Data System (ADS)

    Williams, Michael; Milone, E. F.

    2005-08-01

    We describe a variable-star search program being carried out on a 0.5-m f/1 Patrol Camera at the RAO. The detector is a 4K × 4K chip mounted in an FLI camera, purchased by P. Brown (UWO). The 4.4 by 4.4 degree image frames provide stellar images of ~2 pixels (FWHM). Results from the first well-studied night sequence reveal a significant number of apparently real variability detections. Most of the variability is seen in stars in the range 11 to 14 magnitudes in the natural system (approximately Johnson-Cousins R), with < 0.1 mag 1 sigma errors. Theoretical predictions show that we should be able to achieve 1 sigma errors smaller than 0.02 mag for stars brighter than ~12 mag. Results show that we are close to the theoretical noise levels. In this first surveyed field there are 1100 stars with 1 sigma error levels below 0.02 mag, so this search program is expected to yield a large number of low-amplitude detections. The Patrol Camera is a former Baker- Nunn satellite tracking camera, modified by DFM Engineering as part of a retrofit supervised by M.J. Mazur, in a collaboration funded by grants from the Alberta Science Research Authority (to EFM), and others (to A. Hildebrand and P. Brown). The modifications included replacement of the original tri-axial with an equatorial mounting and the curved-film plane with the 4k CCD array. The paper will describe the data set, search software, sample light curves, and new variablestar discoveries. The survey is being carried out by MDWas part of his Ph.D. program and is being supported in part by NSERC grants to EFM and the University of Calgary Department of Physics & Astronomy.

  17. The novel sigma-2 receptor ligand SW43 stabilizes pancreas cancer progression in combination with gemcitabine

    PubMed Central

    2010-01-01

    Background Sigma-2 receptors are over-expressed in proliferating cancer cells, making an attractive target for the targeted treatment of pancreatic cancer. In this study, we investigated the role of the novel sigma-2 receptor ligand SW43 to induce apoptosis and augment standard chemotherapy. Results The binding affinity for sigma-2 ligands is high in pancreas cancer, and they induce apoptosis with a rank order of SV119 < SW43 < SRM in vitro. Combining these compounds with gemcitabine further increased apoptosis and decreased viability. Our in vivo model showed that sigma-2 ligand treatment decreased tumor volume to the same extent as gemcitabine. However, SW43 combination treatment with gemcitabine was superior to the other compounds and resulted in stabilization of tumor volume during treatment, with minimal toxicities. Conclusions This study shows that the sigma-2 ligand SW43 has the greatest capacity to augment gemcitabine in a pre-clinical model of pancreas cancer and has provided us with the rationale to move this compound forward with clinical investigations for patients with pancreatic cancer. PMID:21092190

  18. Boundary conditions and the generalized metric formulation of the double sigma model

    NASA Astrophysics Data System (ADS)

    Ma, Chen-Te

    2015-09-01

    Double sigma model with strong constraints is equivalent to the ordinary sigma model by imposing a self-duality relation. The gauge symmetries are the diffeomorphism and one-form gauge transformation with the strong constraints. We consider boundary conditions in the double sigma model from three ways. The first way is to modify the Dirichlet and Neumann boundary conditions with a fully O (D, D) description from double gauge fields. We perform the one-loop β function for the constant background fields to find low-energy effective theory without using the strong constraints. The low-energy theory can also have O (D, D) invariance as the double sigma model. The second way is to construct different boundary conditions from the projectors. The third way is to combine the antisymmetric background field with field strength to redefine an O (D, D) generalized metric. We use this generalized metric to reconstruct a consistent double sigma model with the classical and quantum equivalence.

  19. Biperiden hydrochlorate ameliorates dystonia of rats produced by microinjection of sigma ligands into the red nucleus.

    PubMed

    Yoshida, K; Takahashi, H; Sato, K; Higuchi, H; Shimizu, T

    2000-11-01

    It has been reported that the imbalance of anticholinergic and antidopaminergic activity of each neuroleptic drug correlates with the capacity to produce neuroleptic-induced acute dystonia (NAD) and the major focus of NAD is thought to be the striatum. Anticholinergic drugs are highly effective on NAD, but they are partially effective on neuroleptic-induced tardive dystonia and their effect on idiopathic dystonia is disappointing. Recently, it has been reported that the unilateral microinjection of sigma (sigma) ligands into the red nucleus induces torticollis of rats. This animal model appears to be a model of dystonia, but it is not clear whether it is suitable for NAD in man. To clarify this issue, we investigated the effect of an anticholinergic drug, biperiden hydrochlorate (BH), on this animal model. This study revealed that BH dose-dependently ameliorated dystonia of rats induced by two sigma ligands, whether each sigma ligand had dopaminergic affinity or not. This animal model of dystonia appears to be a model of NAD in man from the viewpoint of treatment-response. The results also suggest that not only dopaminergic and cholinergic systems but also sigma system, and not only the striatum but also the red nucleus, may play an important role in the pathophysiology of NAD.

  20. A novel sigma factor reveals a unique regulon controlling cell-specific recombination in Mycoplasma genitalium

    PubMed Central

    Torres-Puig, Sergi; Broto, Alicia; Querol, Enrique; Piñol, Jaume; Pich, Oscar Q.

    2015-01-01

    The Mycoplasma genitalium MG428 protein shows homology to members of the sigma-70 family of sigma factors. Herein, we found that MG428 activates transcription of recA, ruvA and ruvB as well as several genes with unknown function. Deletion of MG_428 or some of the up-regulated unknown genes led to severe recombination defects. Single cell analyses revealed that activation of the MG428-regulon is a rare event under laboratory growth conditions. A conserved sequence with sigma-70 promoter architecture (TTGTCA-N18/19-ATTWAT) was identified in the upstream region of all of the MG428-regulated genes or operons. Primer extension analyses demonstrated that transcription initiates immediately downstream of this sigma70-type promoter in a MG428-dependent manner. Furthermore, mutagenesis of the conserved −10 and −35 elements corroborated the requirement of these regions for promoter function. Therefore, a new mycoplasma promoter directs transcription of a unique recombination regulon. Additionally, MG428 was found to interact with the RNAP core enzyme, reinforcing the predicted role of this protein as an alternative sigma factor. Finally, our results indicate that MG428 contributes to the generation of genetic diversity in this model organism. Since recombination is an important mechanism to generate antigenic variation, MG428 emerges as a novel factor contributing to M. genitalium virulence. PMID:25925568

  1. A novel sigma factor reveals a unique regulon controlling cell-specific recombination in Mycoplasma genitalium.

    PubMed

    Torres-Puig, Sergi; Broto, Alicia; Querol, Enrique; Piñol, Jaume; Pich, Oscar Q

    2015-05-26

    The Mycoplasma genitalium MG428 protein shows homology to members of the sigma-70 family of sigma factors. Herein, we found that MG428 activates transcription of recA, ruvA and ruvB as well as several genes with unknown function. Deletion of MG_428 or some of the up-regulated unknown genes led to severe recombination defects. Single cell analyses revealed that activation of the MG428-regulon is a rare event under laboratory growth conditions. A conserved sequence with sigma-70 promoter architecture (TTGTCA-N(18/19)-ATTWAT) was identified in the upstream region of all of the MG428-regulated genes or operons. Primer extension analyses demonstrated that transcription initiates immediately downstream of this sigma70-type promoter in a MG428-dependent manner. Furthermore, mutagenesis of the conserved -10 and -35 elements corroborated the requirement of these regions for promoter function. Therefore, a new mycoplasma promoter directs transcription of a unique recombination regulon. Additionally, MG428 was found to interact with the RNAP core enzyme, reinforcing the predicted role of this protein as an alternative sigma factor. Finally, our results indicate that MG428 contributes to the generation of genetic diversity in this model organism. Since recombination is an important mechanism to generate antigenic variation, MG428 emerges as a novel factor contributing to M. genitalium virulence. PMID:25925568

  2. Nonlinear consider covariance analysis using a sigma-point filter formulation

    NASA Technical Reports Server (NTRS)

    Lisano, Michael E.

    2006-01-01

    The research reported here extends the mathematical formulation of nonlinear, sigma-point estimators to enable consider covariance analysis for dynamical systems. This paper presents a novel sigma-point consider filter algorithm, for consider-parameterized nonlinear estimation, following the unscented Kalman filter (UKF) variation on the sigma-point filter formulation, which requires no partial derivatives of dynamics models or measurement models with respect to the parameter list. It is shown that, consistent with the attributes of sigma-point estimators, a consider-parameterized sigma-point estimator can be developed entirely without requiring the derivation of any partial-derivative matrices related to the dynamical system, the measurements, or the considered parameters, which appears to be an advantage over the formulation of a linear-theory sequential consider estimator. It is also demonstrated that a consider covariance analysis performed with this 'partial-derivative-free' formulation yields equivalent results to the linear-theory consider filter, for purely linear problems.

  3. Polarized structure function sigma_lt' for kaon electroproduction in the nucleon resonance region

    SciTech Connect

    Rakhsha Nasseripour; B. Raue; Daniel Carman; Pawel Ambrozewicz

    2008-02-19

    The first measurements of the polarized structure function $\\sigma_{LT'}$ for the reaction $p(\\vec e,e'K^+)\\Lambda$ in the nucleon resonance region are reported. Measurements are included from threshold up to $W$=2.05~GeV for central values of $Q^2$ of 0.65 and 1.00~GeV$^2$, and nearly the entire kaon center-of-mass angular range. $\\sigma_{LT'}$ is the imaginary part of the longitudinal-transverse response and is expected to be sensitive to interferences between competing intermediate $s$-channel resonances, as well as resonant and non-resonant processes. The results for $\\sigma_{LT'}$ are comparable in magnitude to previously reported results from CLAS for $\\sigma_{LT}$, the real part of the same response. An intriguing sign change in $\\sigma_{LT'}$ is observed in the high $Q^2$ data at $W\\approx 1.9$~GeV. Comparisons to several existing model predictions are shown.

  4. On the conversion of neutron stars into quark stars

    NASA Astrophysics Data System (ADS)

    Pagliara, Giuseppe

    2014-03-01

    The possible existence of two families of compact stars, neutron stars and quark stars, naturally leads to a scenario in which a conversion process between the two stellar objects occurs with a consequent release of energy of the order of 1053 erg. We discuss recent hydrodynamical simulations of the burning process and neutrino diffusion simulations of cooling of a newly formed strange star. We also briefly discuss this scenario in connection with recent measurements of masses and radii of compact stars.

  5. Mass loss of massive stars

    NASA Astrophysics Data System (ADS)

    Martins, F.

    2015-12-01

    In this contribution we review the properties of the winds of massive stars. We focus on OB stars, red supergiants, Luminous Blue Variables (LBVs) and Wolf-Rayet stars. For each type of star, we summarize the main wind properties and we give a brief description of the physical mechanism(s) responsible for mass loss.

  6. In-Situ Observations of Sigma Phase Dissolution in 2205 Duplex Stainless Steel Using Synchrotron X-Ray Diffraction

    SciTech Connect

    Elmer, J. W.; Palmer, T. A.; Specht, Eliot D

    2007-01-01

    Synchrotron radiation was used to directly observe the transformation of ferrite, austenite and sigma phases during heating and cooling of 2205 duplex stainless steel. Sigma formed during the initial stages of heating, dissolved as the temperature was increased, and reformed on cooling. The dissolution temperature of sigma was measured to be 985 2.8 C at a heating rate of 0.25 C/s, and the kinetics of sigma formation at 850 Cwas determined to be slower after dissolving at 1000 C than before.

  7. In-Situ Observations of Sigma Phase Dissolution in 2205 Duplex Stainless Steel using Synchrotron X-Ray Diffraction

    SciTech Connect

    Elmer, J; Palmer, T; Specht, E

    2006-08-08

    Synchrotron radiation was used to directly observe the transformation of ferrite, austenite and sigma phases during heating and cooling of 2205 duplex stainless steel. Sigma formed during the initial stages of heating, dissolved as the temperature was increased, and reformed on cooling. The dissolution temperature of sigma was measured to be 985 C {+-} 2.8 C at a heating rate of 0.25 C/s, and the kinetics of sigma formation at 850 C was determined to be slower after dissolving at 1000 C than before.

  8. The origin of stars

    NASA Astrophysics Data System (ADS)

    Smith, Michael D.

    Where do stars come from and how do they form? These are profound questions which link the nature of our Universe to the roots of mankind. Yet, until a recent revolution in understanding, the proposed answers have been raw speculation. Now, accompanying penetrating observations, a new picture has come into prominence. This book presents the latest astounding observations and scientific ideas covering star formation, star birth and early development. It encompasses all aspects, from the dramatic stories of individual objects, to the collective influence of entire stellar systems. The very first stars to come into existence and the nurturing of planets are discussed to provide the reader with a comprehensive overview. Presenting background information with only the essential mathematics, this book will appeal to scientists wishing to expand their horizons, students seeking solid foundations, and general readers with enquiring minds.

  9. Discovery of variable stars

    NASA Technical Reports Server (NTRS)

    Kurochkin, N. Y.

    1973-01-01

    Instrumented methods of discovering variable stars are reviewed, specifically the blink comparator, color contrast method, positive-negative method, and television method. Among the empirical methods discussed, the Van Gent method is the most important.

  10. Planets Around Neutron Stars

    NASA Technical Reports Server (NTRS)

    Wolszczan, Alexander; Kulkarni, Shrinivas R; Anderson, Stuart B.

    2003-01-01

    The objective of this proposal was to continue investigations of neutron star planetary systems in an effort to describe and understand their origin, orbital dynamics, basic physical properties and their relationship to planets around normal stars. This research represents an important element of the process of constraining the physics of planet formation around various types of stars. The research goals of this project included long-term timing measurements of the planets pulsar, PSR B1257+12, to search for more planets around it and to study the dynamics of the whole system, and sensitive searches for millisecond pulsars to detect further examples of old, rapidly spinning neutron stars with planetary systems. The instrumentation used in our project included the 305-m Arecibo antenna with the Penn State Pulsar Machine (PSPM), the 100-m Green Bank Telescope with the Berkeley- Caltech Pulsar Machine (BCPM), and the 100-m Effelsberg and 64-m Parkes telescopes equipped with the observatory supplied backend hardware.

  11. Winds from cool stars

    NASA Technical Reports Server (NTRS)

    Dupree, A. K.

    1995-01-01

    Spectral observations of cool stars enable study of the presence and character of winds and the mass loss process in objects with effective temperatures, gravities, and atmospheric compositions which differ from that of the Sun. A wealth of recent spectroscopic measurements from the Hubble Space Telescope, and the Extreme Ultraviolet Explorer complement high resolution ground-based measures in the optical and infrared spectral regions. Such observations when combined with realistic semi-empirical atmospheric modeling allow us to estimate the physical conditions in the atmospheres and winds of many classes of cool stars. Line profiles support turbulent heating and mass motions. In low gravity stars, evidence is found for relatively fast (approximately 200 km s(exp -1)), warm winds with rapid acceleration occurring in the chromosphere. In some cases outflows commensurate with stellar escape velocities are present. Our current understanding of cool star winds will be reviewed including the implications of stellar observations for identification of atmospheric heating and acceleration processes.

  12. Cosmology with hypervelocity stars

    SciTech Connect

    Loeb, Abraham

    2011-04-01

    In the standard cosmological model, the merger remnant of the Milky Way and Andromeda (Milkomeda) will be the only galaxy remaining within our event horizon once the Universe has aged by another factor of ten, ∼ 10{sup 11} years after the Big Bang. After that time, the only extragalactic sources of light in the observable cosmic volume will be hypervelocity stars being ejected continuously from Milkomeda. Spectroscopic detection of the velocity-distance relation or the evolution in the Doppler shifts of these stars will allow a precise measurement of the vacuum mass density as well as the local matter distribution. Already in the near future, the next generation of large telescopes will allow photometric detection of individual stars out to the edge of the Local Group, and may target the ∼ 10{sup 5±1} hypervelocity stars that originated in it as cosmological tracers.

  13. Spectroscopy among the stars.

    PubMed

    Winnewisser, G

    1996-06-01

    The space between the stars is not void, but filled with interstellar matter, mainly composed of dust and gas, which gather in large interstellar clouds. In our Galaxy these interstellar clouds are distributed along a thin, but extended layer which basically traces out the spiral distribution of matter: the stars, the gas, and the dust component. Up to the present time more than 100 different molecules have been identified in interstellar molecular clouds. The majority of the interstellar molecules constitute carbon containing organic substances. During the past years, overwhelming evidence has been gathered, mainly through spectroscopic observations, that interstellar molecular clouds provide the birthplaces for stars. In fact detailed high spectral and spatial resolution spectroscopic measurements reveal physical and chemical processes of the intricate star formation process.

  14. Worlds around other stars

    NASA Astrophysics Data System (ADS)

    Black, David C.

    1991-01-01

    The possible, though tentative, detection of planetary companions to other stars which may be capable of supporting life as we know it through the use of a new generation of detectors and telescopes, combined with some innovative detection techniques, is discussed. The current view of the origin of the solar system, based on the nebular hypothesis, is discussed as it pertains to the formation of how and where planets form and, hence, how and where to search for them. Both direct methods of search for other planetary systems, which involve detecting reflected light or infrared radiation form the planets themselves, and indirect methods, which involve the scrutinization of a star for signs that it is responding to the gravitational tug of an orbiting planet, are discussed at length. In particular, various methods for detecting minute velocity perturbations of stars are discussed. It is noted that the study of brown dwarfs may also provide clues on the formation of stars and planets.

  15. Temperature of neutron stars

    NASA Astrophysics Data System (ADS)

    Tsuruta, Sachiko

    2016-07-01

    We start with a brief introduction to the historical background in the early pioneering days when the first neutron star thermal evolution calculations predicted the presence of neutron stars hot enough to be observable. We then report on the first detection of neutron star temperatures by ROSAT X-ray satellite, which vindicated the earlier prediction of hot neutron stars. We proceed to present subsequent developments, both in theory and observation, up to today. We then discuss the current status and the future prospect, which will offer useful insight to the understanding of basic properties of ultra-high density matter beyond the nuclear density, such as the possible presence of such exotic particles as pion condensates.

  16. Cooling of neutron stars

    NASA Technical Reports Server (NTRS)

    Pethick, C. J.

    1992-01-01

    It is at present impossible to predict the interior constitution of neutron stars based on theory and results from laboratory studies. It has been proposed that it is possible to obtain information on neutron star interiors by studying thermal radiation from their surfaces, because neutrino emission rates, and hence the temperature of the central part of a neutron star, depend on the properties of dense matter. The theory predicts that neutron stars cool relatively slowly if their cores are made up of nucleons, and cool faster if the matter is in an exotic state, such as a pion condensate, a kaon condensate, or quark matter. This view has recently been questioned by the discovery of a number of other processes that could lead to copious neutrino emission and rapid cooling.

  17. Women and the Stars.

    ERIC Educational Resources Information Center

    Spradley, Joseph L.

    1990-01-01

    Described are the contributions of 15 women astronomers to the modern understanding of the stars. Discussed are early women pioneers, early spectrographic studies, and recent women astronomers. A list of 29 references is included. (CW)

  18. Sounds of a Star

    NASA Astrophysics Data System (ADS)

    2001-06-01

    Acoustic Oscillations in Solar-Twin "Alpha Cen A" Observed from La Silla by Swiss Team Summary Sound waves running through a star can help astronomers reveal its inner properties. This particular branch of modern astrophysics is known as "asteroseismology" . In the case of our Sun, the brightest star in the sky, such waves have been observed since some time, and have greatly improved our knowledge about what is going on inside. However, because they are much fainter, it has turned out to be very difficult to detect similar waves in other stars. Nevertheless, tiny oscillations in a solar-twin star have now been unambiguously detected by Swiss astronomers François Bouchy and Fabien Carrier from the Geneva Observatory, using the CORALIE spectrometer on the Swiss 1.2-m Leonard Euler telescope at the ESO La Silla Observatory. This telescope is mostly used for discovering exoplanets (see ESO PR 07/01 ). The star Alpha Centauri A is the nearest star visible to the naked eye, at a distance of a little more than 4 light-years. The new measurements show that it pulsates with a 7-minute cycle, very similar to what is observed in the Sun . Asteroseismology for Sun-like stars is likely to become an important probe of stellar theory in the near future. The state-of-the-art HARPS spectrograph , to be mounted on the ESO 3.6-m telescope at La Silla, will be able to search for oscillations in stars that are 100 times fainter than those for which such demanding observations are possible with CORALIE. PR Photo 23a/01 : Oscillations in a solar-like star (schematic picture). PR Photo 23b/01 : Acoustic spectrum of Alpha Centauri A , as observed with CORALIE. Asteroseismology: listening to the stars ESO PR Photo 23a/01 ESO PR Photo 23a/01 [Preview - JPEG: 357 x 400 pix - 96k] [Normal - JPEG: 713 x 800 pix - 256k] [HiRes - JPEG: 2673 x 3000 pix - 2.1Mb Caption : PR Photo 23a/01 is a graphical representation of resonating acoustic waves in the interior of a solar-like star. Red and blue

  19. The Pistol Star

    NASA Astrophysics Data System (ADS)

    Figer, D. F.; Morris, M.; McLean, I. S.; Ghez, A. M.; Najarro, F.; Geballe, T. R.; Serabyn, E.; Rich, R. M.

    1998-01-01

    We present near-infrared spectra, photometry (JHK(') nbL), and Keck K-band speckle images of the ``Pistol Star.'' We also present HST/NICMOS Paschen-alpha images and near-infrared spectra of the surrounding HII region (G0.15-0.05), the ``Pistol.'' The stellar spectra cover the J, H, and K bands at low resolution, and between 1.80 to 1.96 \\micron, 2.10 to 2.26 \\micron, and 4.02 to 4.08 \\micron\\ at moderate resolution. The spectra of the Pistol cover the K-band at low resolution and 1.80 to 1.96 \\micron\\ at moderate resolution. The stellar data are fit with wind/atmosphere models to find that the star is extraordinarily luminous, having L = 10(6.7({+0.5}_{-0.5})) L_sun, making it one of the most luminous stars known; the range in luminosity is primarily due to uncertainties in extinction and intrinsic spectral energy distribution of the star. Coupled with the relatively cool temperature, T_eff = 10(4.17({+0.19}_{-0.06})) K, the star is clearly in violation of the Humphreys-Davidson limit. The line of sight velocity of the star is confirmed to be ~ 130 kms(-1) , assuring membership in the Quintuplet cluster. This, along with the inferred extinction, places the star at the Galactic Center. The spectra of the Pistol confirm that the ionized gas has smoothly varying velocity gradients superposed on a bulk velocity of 130 kms(-1) . Radio and near-infrared hydrogen-to-helium line ratios suggest that the Pistol may have extrasolar helium abundance and that it must be excited, in part, by a star which is hotter than the Pistol Star. The morphology of the gas, the velocities in the gas, and the location of the star in the HR diagram suggest that the gas in G0.15-0.05 is matter which was ejected from the star.

  20. Catch a Star 2008!

    NASA Astrophysics Data System (ADS)

    2007-10-01

    ESO and the European Association for Astronomy Education have just launched the 2008 edition of 'Catch a Star', their international astronomy competition for school students. Now in its sixth year, the competition offers students the chance to win a once-in-a-lifetime trip to ESO's flagship observatory in Chile, as well as many other prizes. CAS logo The competition includes separate categories - 'Catch a Star Researchers' and 'Catch a Star Adventurers' - to ensure that every student, whatever their level, has the chance to enter and win exciting prizes. In teams, students investigate an astronomical topic of their choice and write a report about it. An important part of the project for 'Catch a Star Researchers' is to think about how ESO's telescopes such as the Very Large Telescope (VLT) or future telescopes such as the Atacama Large Millimeter/submillimeter Array (ALMA) and the European Extremely Large Telescope (E-ELT) could contribute to investigations of the topic. Students may also include practical activities such as observations or experiments. For the artistically minded, 'Catch a Star' also offers an artwork competition, 'Catch a Star Artists'. Last year, hundreds of students from across Europe and beyond took part in 'Catch a Star', submitting astronomical projects and artwork. "'Catch a Star' gets students thinking about the wonders of the Universe and the science of astronomy, with a chance of winning great prizes. It's easy to take part, whether by writing about astronomy or creating astronomically inspired artwork," said Douglas Pierce-Price, Education Officer at ESO. As well as the top prize - a trip to ESO's Very Large Telescope in Chile - visits to observatories in Austria and Spain, and many other prizes, can also be won. 'Catch a Star Researchers' winners will be chosen by an international jury, and 'Catch a Star Adventurers' will be awarded further prizes by lottery. Entries for 'Catch a Star Artists' will be displayed on the web and winners

  1. Measurement of R = {sigma}{sub L}/{sigma}{sub T} and the Separated Longitudinal and Transverse Structure Functions in the Nucleon Resonance Region

    SciTech Connect

    Yongguang Liang; Michael Christy; Abdellah Ahmidouch; Christopher Armstrong; John Arrington; Arshak Asaturyan; Steven Avery; O. Baker; Douglas Beck; Henk Blok; C.W. Bochna; Werner Boeglin; Peter Bosted; Maurice Bouwhuis; Herbert Breuer; Daniel Brown; Antje Bruell; Roger Carlini; Jinseok Cha; Nicholas Chant; Anthony Cochran; Leon Cole; Samuel Danagoulian; Donal Day; James Dunne; Dipangkar Dutta; Rolf Ent; Howard Fenker; B. Fox; Liping Gan; Haiyan Gao; Kenneth Garrow; David Gaskell; Ashot Gasparian; Don Geesaman; Ronald Gilman; Paul Gueye; Mark Harvey; Roy Holt; Xiaodong Jiang; Mark Jones; Cynthia Keppel; Edward Kinney; Wolfgang Lorenzon; Allison Lung; David Mack; Pete Markowitz; J.W. Martin; Kevin McIlhany; Daniella Mckee; David Meekins; M.A. Miller; Richard Milner; Joseph Mitchell; Hamlet Mkrtchyan; Robert Mueller; Alan Nathan; Gabriel Niculescu; Maria-Ioana Niculescu; Thomas O'neill; Vassilios Papavassiliou; Stephen Pate; Rodney Piercey; David Potterveld; Ronald Ransome; Joerg Reinhold; E. Rollinde; Oscar Rondon-Aramayo; Philip Roos; Adam Sarty; Reyad Sawafta; Elaine Schulte; Edwin Segbefia; C. Smith; Samuel Stepanyan; Steffen Strauch; Vardan Tadevosyan; Liguang Tang; Raphael Tieulent; Vladas Tvaskis; Alicia Uzzle; William Vulcan; Stephen Wood; Feng Xiong; Lulin Yuan; Markus Zeier; Benedikt Zihlmann; Vitaliy Ziskin

    2004-10-01

    We report on a detailed study of longitudinal strength in the nucleon resonance region, presenting new results from inclusive electron-proton cross sections measured at Jefferson Lab Hall C in the four-momentum transfer range 0.2 < Q{sup 2} < 5.5 GeV{sup 2}. The data have been used to accurately perform over 170 Rosenbluth-type longitudinal/transverse separations. The precision R = {sigma}{sub L}/{sigma}{sub T} data are presented here, along with the first separate values of the inelastic structure functions F{sub 1} and F{sub L} in this regime. The resonance longitudinal component is found to be significant. With the new data, quark-hadron duality is observed above Q{sup 2} = 1 GeV{sup 2} in the separated structure functions independently.

  2. Laser-induced emission of SO in matrices - The c 1Sigma(-) - a 1Delta and the A prime 3Delta - X 3Sigma(-) transitions

    NASA Astrophysics Data System (ADS)

    Zen, Ching-Chi; Tang, Fa-Tai; Lee, Yuan-Pern

    1992-06-01

    The laser-induced matrix emission technique, using a KrF excimer laser and the experimental setup described by Chiang and Lee (1988), was used to determine accurately the peak positions and isotopic shifts of the two progressions assigned to SO (one in the range 353-601 nm and the other in the range 491-822 nm). The precursors of SO used in this study included Cl2SO, SO2, OCS/NO2, and OCS/N2O. The blue progression is assigned to the A-prime 3Delta - X 3Sigma(-) transition, and the red progression to the c 1Sigma(-) - a 1Delta transition. The energies of the c and the A-prime states are determined.

  3. Ancillary services in the health care industry: is Six Sigma reasonable?

    PubMed

    Johnstone, Peter A S; Hendrickson, Julie A W; Dernbach, Allison J; Secord, Ann R; Parker, John C; Favata, Michael A; Puckett, Michael L

    2003-01-01

    Within the naval medical center construct, the disparate disciplines encompassed within ancillary services lend themselves to formal quality analysis and process improvement. This analysis uses the Six Sigma approach. Error rates were investigated and calculated for various processes within ancillary services at Naval Medical Center, San Diego. These were translated into the common metric of defects per million opportunities (DPMO). DPMO rates vary between 21.5 and 420,000. These correspond to Sigma values from 1.7 to approaching 6. Rates vary with biological complexity of the system and the degree of automation available. Some ancillary services translate well into a Six Sigma schema. Systems with high potential patient risk if performed poorly and those amenable to second checking and computer oversight may be candidates for such optimization. This should be undertaken in a local environment conducive to individual error reporting, and in a corporate environment with the will and funding to support the transition. PMID:12593375

  4. Radiative decays of the Sigma0(1385) and Lambda(1520) hyperons

    SciTech Connect

    Simon Taylor; Gordon Mutchler; CLAS Collaboration

    2005-03-01

    The electromagnetic decays of the {Sigma}{sup 0}(1385) and {Lambda}(1520) hyperons were studied in photon-induced reactions {gamma} p {yields} K{sup +} {Lambda}(1116){gamma} in the CLAS detector at the Thomas Jefferson National Accelerator Facility. We report the first observation of the radiative decay of the {Sigma}{sup 0}(1385) and a measurement of the {Lambda}(1520) radiative decay width. For the {Sigma}{sup 0}(1385) {yields} {Lambda}(1116){gamma} transition, we measured a partial width of 479 {+-} 120(stat){sub -100}{sup +81}(sys) keV, larger than all of the existing model predictions. For the {Lambda}(1520) {yields} {Lambda}(1116){gamma} transition, we obtained a partial width of 167 {+-} 43(stat){sub -12}{sup +26}(sys) keV.

  5. Ancillary services in the health care industry: is Six Sigma reasonable?

    PubMed

    Johnstone, Peter A S; Hendrickson, Julie A W; Dernbach, Allison J; Secord, Ann R; Parker, John C; Favata, Michael A; Puckett, Michael L

    2003-01-01

    Within the naval medical center construct, the disparate disciplines encompassed within ancillary services lend themselves to formal quality analysis and process improvement. This analysis uses the Six Sigma approach. Error rates were investigated and calculated for various processes within ancillary services at Naval Medical Center, San Diego. These were translated into the common metric of defects per million opportunities (DPMO). DPMO rates vary between 21.5 and 420,000. These correspond to Sigma values from 1.7 to approaching 6. Rates vary with biological complexity of the system and the degree of automation available. Some ancillary services translate well into a Six Sigma schema. Systems with high potential patient risk if performed poorly and those amenable to second checking and computer oversight may be candidates for such optimization. This should be undertaken in a local environment conducive to individual error reporting, and in a corporate environment with the will and funding to support the transition.

  6. Timeliness “at a glance”: assessing the turnaround time through the six sigma metrics.

    PubMed

    Ialongo, Cristiano; Bernardini, Sergio

    2016-01-01

    Almost thirty years of systematic analysis have proven the turnaround time to be a fundamental dimension for the clinical laboratory. Several indicators are to date available to assess and report quality with respect to timeliness, but they sometimes lack the communicative immediacy and accuracy. The six sigma is a paradigm developed within the industrial domain for assessing quality and addressing goal and issues. The sigma level computed through the Z-score method is a simple and straightforward tool which delivers quality by a universal dimensionless scale and allows to handle non-normal data. Herein we report our preliminary experience in using the sigma level to assess the change in urgent (STAT) test turnaround time due to the implementation of total automation. We found that the Z-score method is a valuable and easy to use method for assessing and communicating the quality level of laboratory timeliness, providing a good correspondence with the actual change in efficiency which was retrospectively observed.

  7. a Search for a Bound Sigma Hypernuclei in the a = 3 System

    NASA Astrophysics Data System (ADS)

    Barakat, Mohamad Basem

    The search for a bound Sigma hypernuclei state in the A = 3, 4 systems was undertaken at the AGS using the Hypernuclear Spectrometer, "MOBY DICK" and the secondary Kaon beam line, LESBII at an incident momentum of 600 Mev/c. Both liquid ^3He and ^4He targets were used. An analysis of the ^{3}He(K ^{-}/,pi^{+ })X data tagged by two charged particles decay mode of the recoil system unveiled some strength in the EE (Excitation Energy) spectrum just below the Sigma^-D threshold. On the other hand, Monte Carlo simulation of the various decay modes of the formed recoil system revealed that the above strength is consistent with the formation of a Sigma ^circ nn system. A theoretical background and experimental arrangements are given in Chapters one and two; while a detailed analysis and discussion of the ^3He(K^-,pi^+)X reaction data are presented in Chapters three and four respectively.

  8. Star of Bethlehem

    NASA Astrophysics Data System (ADS)

    Hughes, D.; Murdin, P.

    2001-07-01

    The biblical Star of Bethlehem, which heralded the birth of Jesus Christ, is only mentioned in the Gospel of St Matthew 2. The astrologically significant 7 bc triple conjunction of Jupiter and Saturn in the constellation of Pisces is the most likely candidate, although a comet/nova in 5 bc and a comet in 4 bc cannot be ruled out. There is also the possibility that the star was simply fictitious....

  9. Bubbly Little Star

    NASA Technical Reports Server (NTRS)

    2007-01-01

    In this processed Spitzer Space Telescope image, baby star HH 46/47 can be seen blowing two massive 'bubbles.' The star is 1,140 light-years away from Earth.

    The infant star can be seen as a white spot toward the center of the Spitzer image. The two bubbles are shown as hollow elliptical shells of bluish-green material extending from the star. Wisps of green in the image reveal warm molecular hydrogen gas, while the bluish tints are formed by starlight scattered by surrounding dust.

    These bubbles formed when powerful jets of gas, traveling at 200 to 300 kilometers per second, or about 120 to 190 miles per second, smashed into the cosmic cloud of gas and dust that surrounds HH 46/47. The red specks at the end of each bubble show the presence of hot sulfur and iron gas where the star's narrow jets are currently crashing head-on into the cosmic cloud's gas and dust material.

    Whenever astronomers observe a star, or snap a stellar portrait, through the lens of any telescope, they know that what they are seeing is slightly blurred. To clear up the blurring in Spitzer images, astronomers at the Jet Propulsion Laboratory developed an image processing technique for Spitzer called Hi-Res deconvolution.

    This process reduces blurring and makes the image sharper and cleaner, enabling astronomers to see the emissions around forming stars in greater detail. When scientists applied this image processing technique to the Spitzer image of HH 46/47, they were able to see winds from the star and jets of gas that are carving the celestial bubbles.

    This infrared image is a three-color composite, with data at 3.6 microns represented in blue, 4.5 and 5.8 microns shown in green, and 24 microns represented as red.

  10. Chaotic Star Birth

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Click on the image for Poster VersionClick on the image for IRAS 4B Inset

    Located 1,000 light years from Earth in the constellation Perseus, a reflection nebula called NGC 1333 epitomizes the beautiful chaos of a dense group of stars being born. Most of the visible light from the young stars in this region is obscured by the dense, dusty cloud in which they formed. With NASA's Spitzer Space Telescope, scientists can detect the infrared light from these objects. This allows a look through the dust to gain a more detailed understanding of how stars like our sun begin their lives.

    The young stars in NGC 1333 do not form a single cluster, but are split between two sub-groups. One group is to the north near the nebula shown as red in the image. The other group is south, where the features shown in yellow and green abound in the densest part of the natal gas cloud. With the sharp infrared eyes of Spitzer, scientists can detect and characterize the warm and dusty disks of material that surround forming stars. By looking for differences in the disk properties between the two subgroups, they hope to find hints of the star and planet formation history of this region.

    The knotty yellow-green features located in the lower portion of the image are glowing shock fronts where jets of material, spewed from extremely young embryonic stars, are plowing into the cold, dense gas nearby. The sheer number of separate jets that appear in this region is unprecedented. This leads scientists to believe that by stirring up the cold gas, the jets may contribute to the eventual dispersal of the gas cloud, preventing more stars from forming in NGC 1333.

    In contrast, the upper portion of the image is dominated by the infrared light from warm dust, shown as red.

  11. Spectroscopic Binary Stars

    NASA Astrophysics Data System (ADS)

    Batten, A.; Murdin, P.

    2000-11-01

    Historically, spectroscopic binary stars were binary systems whose nature was discovered by the changing DOPPLER EFFECT or shift of the spectral lines of one or both of the component stars. The observed Doppler shift is a combination of that produced by the constant RADIAL VELOCITY (i.e. line-of-sight velocity) of the center of mass of the whole system, and the variable shift resulting from the o...

  12. The Stars Surrounding WR 55

    NASA Astrophysics Data System (ADS)

    Turner, David G.; Forbes, Douglas

    2005-09-01

    Photoelectric UBV photometry is presented for stars in a field closely adjacent to the Wolf-Rayet star WR 55 (WN7) in a search for a possible parent cluster. There is a group of at least eight stars ~7' south-southeast of the WR star forming a newly discovered, sparsely populated open cluster (designated C1331-622), but the stars are only 819+/-26 pc distant, less than a quarter of the predicted distance to WR 55.

  13. STAR facility tritium accountancy

    SciTech Connect

    Pawelko, R. J.; Sharpe, J. P.; Denny, B. J.

    2008-07-15

    The Safety and Tritium Applied Research (STAR) facility has been established to provide a laboratory infrastructure for the fusion community to study tritium science associated with the development of safe fusion energy and other technologies. STAR is a radiological facility with an administrative total tritium inventory limit of 1.5 g (14,429 Ci) [1]. Research studies with moderate tritium quantities and various radionuclides are performed in STAR. Successful operation of the STAR facility requires the ability to receive, inventory, store, dispense tritium to experiments, and to dispose of tritiated waste while accurately monitoring the tritium inventory in the facility. This paper describes tritium accountancy in the STAR facility. A primary accountancy instrument is the tritium Storage and Assay System (SAS): a system designed to receive, assay, store, and dispense tritium to experiments. Presented are the methods used to calibrate and operate the SAS. Accountancy processes utilizing the Tritium Cleanup System (TCS), and the Stack Tritium Monitoring System (STMS) are also discussed. Also presented are the equations used to quantify the amount of tritium being received into the facility, transferred to experiments, and removed from the facility. Finally, the STAR tritium accountability database is discussed. (authors)

  14. STAR Facility Tritium Accountancy

    SciTech Connect

    R. J. Pawelko; J. P. Sharpe; B. J. Denny

    2007-09-01

    The Safety and Tritium Applied Research (STAR) facility has been established to provide a laboratory infrastructure for the fusion community to study tritium science associated with the development of safe fusion energy and other technologies. STAR is a radiological facility with an administrative total tritium inventory limit of 1.5g (14,429 Ci) [1]. Research studies with moderate tritium quantities and various radionuclides are performed in STAR. Successful operation of the STAR facility requires the ability to receive, inventory, store, dispense tritium to experiments, and to dispose of tritiated waste while accurately monitoring the tritium inventory in the facility. This paper describes tritium accountancy in the STAR facility. A primary accountancy instrument is the tritium Storage and Assay System (SAS): a system designed to receive, assay, store, and dispense tritium to experiments. Presented are the methods used to calibrate and operate the SAS. Accountancy processes utilizing the Tritium Cleanup System (TCS), and the Stack Tritium Monitoring System (STMS) are also discussed. Also presented are the equations used to quantify the amount of tritium being received into the facility, transferred to experiments, and removed from the facility. Finally, the STAR tritium accountability database is discussed.

  15. Seeing Stars in Serpens

    NASA Technical Reports Server (NTRS)

    2006-01-01

    Infant stars are glowing gloriously in this infrared image of the Serpens star-forming region, captured by NASA's Spitzer Space Telescope.

    The reddish-pink dots are baby stars deeply embedded in the cosmic cloud of gas and dust that collapsed to create it. A dusty disk of cosmic debris, or 'protoplanetary disk,' that may eventually form planets, surrounds the infant stars.

    Wisps of green throughout the image indicate the presence of carbon rich molecules called polycyclic aromatic hydrocarbons. On Earth, these molecules can be found on charred barbecue grills and in automobile exhaust. Blue specks sprinkled throughout the image are background stars in our Milky Way galaxy.

    The Serpens star-forming region is located approximately 848 light-years away in the Serpens constellation.

    The image is a three-channel, false-color composite, where emission at 4.5 microns is blue, emission at 8.0 microns is green, and 24 micron emission is red.

  16. Barium Stars: Theoretical Interpretation

    NASA Astrophysics Data System (ADS)

    Husti, Laura; Gallino, Roberto; Bisterzo, Sara; Straniero, Oscar; Cristallo, Sergio

    2009-09-01

    Barium stars are extrinsic Asymptotic Giant Branch (AGB) stars. They present the s-enhancement characteristic for AGB and post-AGB stars, but are in an earlier evolutionary stage (main sequence dwarfs, subgiants, red giants). They are believed to form in binary systems, where a more massive companion evolved faster, produced the s-elements during its AGB phase, polluted the present barium star through stellar winds and became a white dwarf. The samples of barium stars of Allen & Barbuy (2006) and of Smiljanic et al. (2007) are analysed here. Spectra of both samples were obtained at high-resolution and high S/N. We compare these observations with AGB nucleosynthesis models using different initial masses and a spread of 13C-pocket efficiencies. Once a consistent solution is found for the whole elemental distribution of abundances, a proper dilution factor is applied. This dilution is explained by the fact that the s-rich material transferred from the AGB to the nowadays observed stars is mixed with the envelope of the accretor. We also analyse the mass transfer process, and obtain the wind velocity for giants and subgiants with known orbital period. We find evidence that thermohaline mixing is acting inside main sequence dwarfs and we present a method for estimating its depth.

  17. Reduction in Chemotherapy Mixing Errors Using Six Sigma: Illinois CancerCare Experience

    PubMed Central

    Heard, Bridgette; Miller, Laura; Kumar, Pankaj

    2012-01-01

    Purpose: Chemotherapy mixing errors (CTMRs), although rare, have serious consequences. Illinois CancerCare is a large practice with multiple satellite offices. The goal of this study was to reduce the number of CTMRs using Six Sigma methods. Patients and Methods: A Six Sigma team consisting of five participants (registered nurses and pharmacy technicians [PTs]) was formed. The team had 10 hours of Six Sigma training in the DMAIC (ie, Define, Measure, Analyze, Improve, Control) process. Measurement of errors started from the time the CT order was verified by the PT to the time of CT administration by the nurse. Data collection included retrospective error tracking software, system audits, and staff surveys. Results: Root causes of CTMRs included inadequate knowledge of CT mixing protocol, inconsistencies in checking methods, and frequent changes in staffing of clinics. Initial CTMRs (n = 33,259) constituted 0.050%, with 77% of these errors affecting patients. The action plan included checklists, education, and competency testing. The postimplementation error rate (n = 33,376, annualized) over a 3-month period was reduced to 0.019%, with only 15% of errors affecting patients. Initial Sigma was calculated at 4.2; this process resulted in the improvement of Sigma to 5.2, representing a 100-fold reduction. Financial analysis demonstrated a reduction in annualized loss of revenue (administration charges and drug wastage) from $11,537.95 (Medicare Average Sales Price) before the start of the project to $1,262.40. Conclusion: The Six Sigma process is a powerful technique in the reduction of CTMRs.

  18. The role of sigmaB in persistence of Staphylococcus epidermidis foreign body infection.

    PubMed

    Pintens, Valerie; Massonet, Caroline; Merckx, Rita; Vandecasteele, Stefaan; Peetermans, Willy E; Knobloch, Johannes K-M; Van Eldere, Johan

    2008-09-01

    Staphylococcal biofilm formation depends on the transcription factor sigma(B). We further investigated the role of sigma(B) in biofilm formation and persistence in vitro and in vivo in a subcutaneous rat model. As expected, expression of all sigma(B) operon genes was transiently higher in the first 6 h of biofilm formation compared to planktonic bacteria, concurrent with a temporary upregulation of icaA and aap expression. However, we also observed a second upregulation of sigB expression in biofilm more than 2 days old without upregulation of icaA or aap. Biofilm formation by Staphylococcus epidermidis strains 8400 and 1457 was compared to that of isogenic mutants with inactivation of rsbU, of rsbUVW and of the entire sigma(B) operon. Both wild-type strains and the constitutively sigB-expressing rsbUVW mutant showed a strong biofilm-positive phenotype. The rsbUVW mutant biofilm was, however, thinner and more evenly spread than the wild-type biofilm. Inactivation of SigB in the rsbUVWsigB mutant or mutation of the positive regulator RsbU reduced both the number of sessile bacteria and polysaccharide intercellular adhesin (PIA) synthesis. These differences between the wild-types and their respective mutants appeared after 6 h in in vitro biofilms but only after 4 days in in vivo biofilms. Our results provide additional evidence for a role for sigma(B) in biofilm formation. They also suggest a role for sigma(B) in biofilm maturation and stability that is independent of PIA or accumulation-associated protein (Aap) and point to significant differences in the temporal development between in vitro and in vivo biofilms.

  19. A Novel Extracytoplasmic Function (ECF) Sigma Factor Regulates Virulence in Pseudomonas aeruginosa

    PubMed Central

    Llamas, María A.; van der Sar, Astrid; Chu, Byron C. H.; Sparrius, Marion; Vogel, Hans J.; Bitter, Wilbert

    2009-01-01

    Next to the two-component and quorum sensing systems, cell-surface signaling (CSS) has been recently identified as an important regulatory system in Pseudomonas aeruginosa. CSS systems sense signals from outside the cell and transmit them into the cytoplasm. They generally consist of a TonB-dependent outer membrane receptor, a sigma factor regulator (or anti-sigma factor) in the cytoplasmic membrane, and an extracytoplasmic function (ECF) sigma factor. Upon perception of the extracellular signal by the receptor the ECF sigma factor is activated and promotes the transcription of a specific set of gene(s). Although most P. aeruginosa CSS systems are involved in the regulation of iron uptake, we have identified a novel system involved in the regulation of virulence. This CSS system, which has been designated PUMA3, has a number of unusual characteristics. The most obvious difference is the receptor component which is considerably smaller than that of other CSS outer membrane receptors and lacks a β-barrel domain. Homology modeling of PA0674 shows that this receptor is predicted to be a bilobal protein, with an N-terminal domain that resembles the N-terminal periplasmic signaling domain of CSS receptors, and a C-terminal domain that resembles the periplasmic C-terminal domains of the TolA/TonB proteins. Furthermore, the sigma factor regulator both inhibits the function of the ECF sigma factor and is required for its activity. By microarray analysis we show that PUMA3 regulates the expression of a number of genes encoding potential virulence factors, including a two-partner secretion (TPS) system. Using zebrafish (Danio rerio) embryos as a host we have demonstrated that the P. aeruginosa PUMA3-induced strain is more virulent than the wild-type. PUMA3 represents the first CSS system dedicated to the transcriptional activation of virulence functions in a human pathogen. PMID:19730690

  20. Allosteric modulation of sigma-1 receptors by SKF83959 inhibits microglia-mediated inflammation.

    PubMed

    Wu, Zhuang; Li, Linlang; Zheng, Long-Tai; Xu, Zhihong; Guo, Lin; Zhen, Xuechu

    2015-09-01

    Recent studies have shown that sigma-1 receptor orthodox agonists can inhibit neuroinflammation. SKF83959 (3-methyl-6-chloro-7,8-hydroxy-1-[3-methylphenyl]-2,3,4,5-tetrahydro-1H-3-benzazepine), an atypical dopamine receptor-1 agonist, has been recently identified as a potent allosteric modulator of sigma-1 receptor. Here, we investigated the anti-inflammatory effects of SKF83959 in lipopolysaccharide (LPS)-stimulated BV2 microglia. Our results indicated that SKF83959 significantly suppressed the expression/release of the pro-inflammatory mediators, such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), inducible nitric oxide synthase (iNOS), and inhibited the generation of reactive oxygen species. All of these responses were blocked by selective sigma-1 receptor antagonists (BD1047 or BD1063) and by ketoconazole (an inhibitor of enzyme cytochrome c17 to inhibit the synthesis of endogenous dehydroepiandrosterone, DHEA). Additionally, we found that SKF83959 promoted the binding activity of DHEA with sigma-1 receptors, and enhanced the inhibitory effects of DHEA on LPS-induced microglia activation in a synergic manner. Furthermore, in a microglia-conditioned media system, SKF83959 inhibited the cytotoxicity of conditioned medium generated by LPS-activated microglia toward HT-22 neuroblastoma cells. Taken together, our study provides the first evidence that allosteric modulation of sigma-1 receptors by SKF83959 inhibits microglia-mediated inflammation. SKF83959 is a potent allosteric modulator of sigma-1 receptor. Our results indicated that SKF83959 enhanced the activity of endogenous dehydroepiandrosterone (DHEA) in a synergic manner, and inhibited the activation of BV2 microglia and the expression/release of the pro-inflammatory mediators, such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), inducible nitric oxide synthase (iNOS).

  1. LINE ABSORPTION OSCILLATOR STRENGTHS FOR THE c'{sub 4}{sup 1}{Sigma}{sup +}{sub u}(3)-X{sup 1}{Sigma}{sup +}{sub g}(0-5) BANDS IN N{sub 2}

    SciTech Connect

    Lavin, C.; Velasco, A. M.

    2011-09-20

    Theoretical absorption oscillator strengths and emission branching ratios for rotational lines of the c'{sub 4}{sup 1}{Sigma}{sup +}{sub u}(3)-X{sup 1}{Sigma}{sup +}{sub g}(0-5) bands of molecular nitrogen are reported. The calculations have been performed with the molecular quantum defect orbital method, which has proved to be reliable in previous studies of rovibronic transitions in diatomic molecules. The strong interaction between c'{sub 4}{sup 1}{Sigma}{sup +}{sub u}(3) and b' {sup 1}{Sigma}{sup +}{sub u}(10) states has been analyzed through an interaction matrix that includes rotational terms. Owing to the perturbation, the c'{sub 4}{sup 1}{Sigma}{sup +}{sub u}(3)-X{sup 1}{Sigma}{sup +}{sub g}(0), c'{sub 4}{sup 1}{Sigma}{sup +}{sub u}(3)-X{sup 1}{Sigma}{sup +}{sub g}(1), and c'{sub 4}{sup 1}{Sigma}{sup +}{sub u}(3)-X{sup 1}{Sigma}{sup +}{sub g}(5) bands are not weak, in contrast to what would be expected on the basis of the Franck-Condon principle. Moreover, the intensity distribution of the rotational lines within each of the vibronic bands deviates from considerations based on Hoenl-London factors. In this work, we provide data that may be useful to interpret spectra from atmospheres of the Earth, Titan, and Triton, in which transitions from the c'{sub 4}{sup 1}{Sigma}{sup +}{sub u}(3) level have been detected.

  2. Precise Astrometry in the Core of the Globular Cluster 47 Tuc: a Complete Census of High-Velocity Stars

    NASA Astrophysics Data System (ADS)

    Meylan, Georges

    1995-07-01

    Binary stars play an essential role during the late phases of the dynamical evolution of a globular cluster. They transfer energy to passing stars, and so can strongly influence the cluster evolution - enough to delay, halt, and even reverse core collapse. Hard binaries are known to exist in cluster cores, e.g., in the form of millisecond pulsars. The presence of hard binaries may also be revealed by searching for the by- products of close encounters: high-velocity stars. Two such stars were serendipitously discovered in the core of 47 Tuc by Meylan et al. (1991), and similar stars have since been detected by Pryor et al. (1994). This represents the limit of the radial velocity data which can be obtained from the ground. If more progress is to be made in the search for high- velocity stars in 47 Tuc it must be made by obtaining proper motions - a task for which only HST is suitable. We propose to use WFPC2 to obtain deep U (F300W) images of the core of 47 Tuc at three different epochs over two years. This will allow us to measure differential proper motions to a 1 sigma limit of 0.23 mas/yr - this corresponds to a 5 sigma detection of all stars with velocities greater than 22 km/s. The choice of F300W will allow stars to be measured over the whole color-magnitude diagram - from the red-giant branch to well down the main sequence. Such a complete census will provide unique constraints on relaxation processes, collision and ejection rates, and velocity distributions.

  3. Precise Astrometry in the Core of the Globular Cluster 47 Tuc: A Complete Census of High-Velocity Stars

    NASA Astrophysics Data System (ADS)

    Meylan, Georges

    1996-07-01

    Binary stars play an essential role during the late phases of the dynamical evolution of a globular cluster. They transfer energy to passing stars, and so can strongly influence the cluster evolution. Hard binaries are known to exist in cluster cores, e.g., in the form of millisecond pulsars. The presence of hard binaries may also be revealed by searching for the by- products of close encounters: high-velocity stars. Two such stars were serendipitously discovered in the core of 47 Tuc by Meylan et al. {1991}, and similar stars have since been detected by Pryor et al. {1994}. This represents the limit of the radial velocity data from the ground. If more progress is to be made in the search for high-velocity stars in 47 Tuc, it must be made by obtaining proper motions, a task for which only HST is suitable. We propose to continue {Cycle 5 observations are scheduled for the fall of 1995} to use WFPC2 to obtain deep U {F300W} images of the core of 47 Tuc at three different epochs over two years. This will allow us to measure differential proper motions to a 1-Sigma limit of 0.23 mas/yr - this corresponds to a 5-Sigma detection of all stars with velocities greater than 22 km/s. The choice of F300W will allow stars to be measured over the whole color-magnitude diagram, from the red-giant branch to well down the main sequence. Such a complete census will provide unique constraints on relaxation processes, collision and ejection rates, and velocity distribution, as a function of the stellar mass.

  4. Precise Astrometry in the Core of the Globular Cluster 47 Tuc: A Complete Census of High-Velocity Stars

    NASA Astrophysics Data System (ADS)

    Meylan, Georges

    1997-07-01

    We propose to obtain the third and final epoch for our measurement of differential proper motions in the core of 47 Tuc using deep U {F300W} and V {F555W} WFPC2 images over two years {1^st epoch: Oct. 1995; 2^nd: Cycle 6 scheduled}. The resulting motions will have a 1-Sigma uncertainty of 0.23 mas/yr - corresponds to a 5-Sigma detection of all stars with velocities greater than 22 km/s. The choice of F300W will allow stars to be measured over the whole color-magnitude diagram, from the red-giant branch to well down the main sequence. Such a complete census will provide unique constraints on relaxation processes, collision and ejection rates, and the velocity distribution, as a function of the stellar mass. Binary stars play an essential role during the late phases of the dynamical evolution of a globular cluster. They transfer energy to passing stars, and so can strongly influence the cluster evolution. Hard binaries are known to exist in cluster cores, e.g., in th e form of millisecond pulsars. Th e presence of hard binaries may also be revealed by searching for the by-products of close encounters: high-velocity stars. Two such stars were serendipitously discovered in the core of 47 Tuc by Meylan et al. {1991}, and similar stars have since been detected by Pryor et al. {1994}. This represents the limit of the radial velocity data from the ground. If more progress is to be made in the search for high-velocity stars in 47 Tuc, it must be made by obtaining proper motions, a task for which only HST is suitable.

  5. Collapsing Enormous Stars

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2015-09-01

    One of the big puzzles in astrophysics is how supermassive black holes (SMBHs) managed to grow to the large sizes weve observed in the very early universe. In a recent study, a team of researchers examines the possibility that they were formed by the direct collapse of supermassive stars.Formation MysterySMBHs billions of times as massive as the Sun have been observed at a time when the universe was less than a billion years old. But thats not enough time for a stellar-mass black hole to grow to SMBH-size by accreting material so another theory is needed to explain the presence of these monsters so early in the universes history. A new study, led by Tatsuya Matsumoto (Kyoto University, Japan), poses the following question: what if supermassive stars in the early universe collapsed directly into black holes?Previous studies of star formation in the early universe have suggested that, in the hot environment of these primordial times, stars might have been able to build up mass much faster than they can today. This could result in early supermassive stars roughly 100,000 times more massive than the Sun. But if these early stars end their lives by collapsing to become massive black holes in the same way that we believe massive stars can collapse to form stellar-mass black holes today this should result in enormously violent explosions. Matusmoto and collaborators set out to model this process, to determine what we would expect to see when it happens!Energetic BurstsThe authors modeled the supermassive stars prior to collapse and then calculated whether a jet, created as the black hole grows at the center of the collapsing star, would be able to punch out of the stellar envelope. They demonstrated that the process would work much like the widely-accepted collapsar model of massive-star death, in which a jet successfully punches out of a collapsing star, violently releasing energy in the form of a long gamma-ray burst (GRB).Because the length of a long GRB is thought to

  6. Genetic and molecular analyses of the interaction between the flagellum-specific sigma and anti-sigma factors in Salmonella typhimurium.

    PubMed

    Kutsukake, K; Iyoda, S; Ohnishi, K; Iino, T

    1994-10-01

    More than 50 genes are required for flagellar formation and function in Salmonella typhimurium. According to the cascade model of flagellar regulon, the flagellar operons are divided into three classes, 1, 2, and 3, with respect to transcriptional hierarchy. FliA is an alternative sigma factor specific for transcription of the class 3 operons, while FlgM is an anti-sigma factor which binds to FliA and prevents its association with RNA polymerase core enzyme. In the present study, we isolated a number of fliA mutants in which the altered FliA proteins become insensitive to inhibition by FlgM. Sequence analysis of their mutation sites revealed that most of them caused the amino acid substitutions in region 4 of the conserved amino acid sequences of sigma factors which lies near the C-terminal end of FliA. Using a set of fliA deletion mutants in a high-expression plasmid, we demonstrated that polypeptides containing the C-terminal portion of FliA could titrate the intracellular FlgM protein resulting in derepression of the class 3 operons. This result indicates that the C-terminal region of FliA contains the FlgM-binding domain. This was confirmed by a chemical cross-linking experiment with FlgM and truncated FliA proteins. PMID:7925298

  7. Lean Six Sigma in health care and the challenge of implementation of Six Sigma methodologies at a Veterans Affairs Medical Center.

    PubMed

    Pocha, Christine

    2010-01-01

    Six Sigma and Lean Thinking are quality initiatives initially deployed in industry to improve operational efficiency leading to better quality and subsequent cost savings. The financial rationale for embarking on this quality journey is clear; applying it to today's health care remains challenging. The cost of medical care is increasing at an alarming rate; most of these cost increases are attributed to an aging population and technological advances; therefore, largely beyond control. Furthermore, health care cost increases are caused by unnecessary operational inefficiency associated with the direct medical service delivery process. This article describes the challenging journey of implementing Six Sigma methodology at a tertiary care medical center. Many lessons were learned; however, of utmost importance were team approach, "buy in" of the stakeholders, and the willingness of team members to change daily practice and to adapt new and innovative ways how health care can be delivered. Six Sigma incorporated as part of the "company's or hospital's culture" would be most desirable but the learning curve will be steep.

  8. A Search for Hard X-ray Emission from Active Stars Using CGRO/BATSE

    NASA Astrophysics Data System (ADS)

    White, S. M.; Harmon, B. A.; Lim, J.; Kundu, M. R.

    We report the results of a search for > 20 keV photons from active stars using CGRO/BATSE Earth-occultation observations. Twelve of the "usual suspects" together with 12 "placebo" locations have been analyzed using the BATSE software for occultation analysis developed at NASA/MSFC. There are four detections at the nominal 5sigma level, and eight at the 3sigma level. However the strongest detection (that of AB Dor) shows clear evidence for contamination from the nearby strong source LMC X-4. 18 of the 24 fields yield positive fluxes, indicating a clear bias in the results, and possibly indicating the presence of weak background hard X-ray sources detectable by BATSE in long-term studies.

  9. Positron attachment to the H{sub 2}(A {sup 3{Sigma}}{sub u}) state

    SciTech Connect

    Mitroy, J.; Zhang, J. Y.

    2011-06-15

    The stochastic variational method is used to compute the binding energy for positrons attached to the repulsive H{sub 2}(A {sup 3{Sigma}}{sub u}) state. Attachment occurs for internuclear separations between 1.616 a{sub 0} and 1.818 a{sub 0}. At these distances the vertical ionization potential for the H{sub 2}(A {sup 3{Sigma}}{sub u}) state is close to the positronium binding energy of 0.250 a.u. The maximum attachment energy occurs at 1.67 a{sub 0} and is 0.003532 a.u.

  10. Moduli-space dynamics of noncommutative abelian sigma-model solitons

    NASA Astrophysics Data System (ADS)

    Klawunn, Michael; Lechtenfeld, Olaf; Petersen, Stefan

    2006-06-01

    In the noncommutative (Moyal) plane, we relate exact U(1) sigma-model solitons to generic scalar-field solitons for an infinitely stiff potential. The static k-lump moduli space Bbb Ck/Sk features a natural Kähler metric induced from an embedding Grassmannian. The moduli-space dynamics is blind against adding a WZW-like term to the sigma-model action and thus also applies to the integrable U(1) Ward model. For the latter's two-soliton motion we compare the exact field configurations with their supposed moduli-space approximations. Surprisingly, the two do not match, which questions the adiabatic method for noncommutative solitons.

  11. Nucleon sigma term and strange quark content from lattice QCD with exact chiral symmetry

    SciTech Connect

    Ohki, H.; Fukaya, H.; Hashimoto, S.; Kaneko, T.; Yamada, N.; Matsufuru, H.; Noaki, J.; Shintani, E.; Onogi, T.

    2008-09-01

    We calculate the nucleon sigma term in two-flavor lattice QCD utilizing the Feynman-Hellman theorem. Both sea and valence quarks are described by the overlap fermion formulation, which preserves exact chiral and flavor symmetries on the lattice. We analyze the lattice data for the nucleon mass using the analytical formulae derived from the baryon chiral perturbation theory. From the data at valence quark mass set different from sea quark mass, we may extract the sea quark contribution to the sigma term, which corresponds to the strange quark content. We find that the strange quark content is much smaller than the previous lattice calculations and phenomenological estimates.

  12. d sigma/dy Distribution of Drell-Yan Dielectron Pairs

    SciTech Connect

    Han, Jiyeon; Bodek, A.; Sakumoto, W.; Chung, Y.; /Rochester U.

    2007-11-01

    The authors report on the measurement of the rapidity distribution, d{sigma}/dY, over the full kinematic range for e{sup +}e{sup -} pairs produced in p{bar p} collisions at {radical}s = 1.96 TeV in the Z boson region of 66 < M{sub ee} < 116 GeV/c{sup 2}. The data sample consists of 1.1 fb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV taken by the Collider Detector at Fermilab (CDF). The d{sigma}/dy is compared with the NLO theory prediction.

  13. Structure of Lambda(1405) and threshold behavior of pi Sigma scattering

    SciTech Connect

    Yoichi Ikeda, Tesuo Hyodo, Daisuke Jido, Hiroyuki Kamano, Toru Sato, Koichi Yazaki

    2011-01-01

    The scattering length and effective range of the pi-Sigma channel are studied in order to characterize the strangeness S = -1 meson-baryon scattering and the Lambda (1405) resonance. We examine various off-shell dependence of the amplitude in dynamical chiral models to evaluate the threshold quantities with the constraint at the KN threshold. We find that the pi-Sigma threshold parameters are important to the structure of the Lambda (1405) resonance and provide further constraints on the subthreshold extrapolation of the KN interaction.

  14. Sigma-1 receptors: a new pathway for the modulation of store-operated calcium entry.

    PubMed

    Rosado, Juan A

    2016-02-01

    SOCE (store-operated Ca(2+) entry) is a ubiquitous mechanism for Ca(2+) influx in animal cells. In a recent issue of the Biochemical Journal, Brailoiu and colleagues reported that cocaine attenuates SOCE in rat brain microvascular endothelial cells, via a mechanism that requires the expression and activation of the sigma-1 receptor, a chaperone located in the endoplasmic reticulum-mitochondrion interface that modulates intracellular Ca(2+) homoeostasis and cell survival. This study envisages a pathway through which cocaine modulates endothelial function via regulation of SOCE. The regulation of SOCE by sigma-1 receptors provides a novel and important pathway in Ca(2+) signalling.

  15. On the classical equivalence of monodromy matrices in squashed sigma model

    NASA Astrophysics Data System (ADS)

    Kawaguchi, Io; Matsumoto, Takuya; Yoshida, Kentaroh

    2012-06-01

    We proceed to study the hybrid integrable structure in two-dimensional non-linear sigma models with target space three-dimensional squashed spheres. A quantum affine algebra and a pair of Yangian algebras are realized in the sigma models and, according to them, there are two descriptions to describe the classical dynamics 1) the trigonometric description and 2) the rational description, respectively. For every description, a Lax pair is constructed and the associated monodromy matrix is also constructed. In this paper we show the gauge-equivalence of the monodromy matrices in the trigonometric and rational description under a certain relation between spectral parameters and the rescalings of sl(2) generators.

  16. SigmaPlot 2000, Version 6.00, SPSS Inc. Computer Software Test Plan

    SciTech Connect

    HURLBUT, S.T.

    2000-10-24

    SigmaPlot is a vendor software product used in conjunction with the supercritical fluid extraction Fourier transform infrared spectrometer (SFE-FTIR) system. This product converts the raw spectral data to useful area numbers. SigmaPlot will be used in conjunction with procedure ZA-565-301, ''Determination of Moisture by Supercritical Fluid Extraction and Infrared Detection.'' This test plan will be performed in conjunction with or prior to HNF-6936, ''HA-53 Supercritical Fluid Extraction System Acceptance Test Plan'', to perform analyses for water. The test will ensure that the software can be installed properly and will manipulate the analytical data correctly.

  17. Plastic Injection Quality Controlling Using the Lean Six Sigma and FMEA Method

    NASA Astrophysics Data System (ADS)

    Mansur, A.; Mu'alim; Sunaryo

    2016-01-01

    PT. Yogya Presisi Teknikatama Industri (PT. YPTI) is a mold, precision part, and plastic injection maker company. One of the obstacles faced by the company is the high level of nonconformity on its production results. The waste on production process can be identified and classified into four types, i.e.: a). during the process of injection molding machines, b). finishing and cutting processes, c). quality control process and d). the packaging process. The objectives of this research are minimizing the defective goods and reducing the waste using Lean Six Sigma and FMEA approaches, especially for Bush product. From the analysis result, defective types on Bush product can be classified into bubble, speckle, short shoot, sunken, sink mark, over-cut, flashing, and discolor. Based on the attributes data on Bush product, the DPMO score is 988.42 or the sigma level is 4.6, While the DPMO score on the variable data on each dimension i.e.: a). Slit width on the bottom side has DPMO score of 30119 (sigma level 3.37), b). Diameter of the circle on the top side has DPMO score of 392294 (sigma level 1.77), c). Product thickness on the top side has DPMO score of 70474 (sigma level 2.97), d). Product height has DPMO score of 82107 (sigma level 2.89), product thickness on the bottom side has DPMO score of 24448 (sigma level 3.47), and f). Diameter of the circle on the bottom side has DPMO score of 24448 (sigma level 3.47). The highest RPN score on the dominant types of product defects which needs improvement are the defective goods of bubble type has RPN score of 729, flashing and the molten material out on the heating channel has RPN score of 384, over cutting has RPN score of 324 and sink mark has RPN score of 270. The recommendations for improvement that can be given from this research are making checklist for maintenance and production monitoring, enhancing work supervision and inspection, as well as improving the environment and work stations.

  18. Predissociation of oxygen in the B3Sigma(u)(-) state

    NASA Technical Reports Server (NTRS)

    Chiu, S. S.-L.; Cheung, A. S.-C.; Finch, M.; Jamieson, M. J.; Yoshino, K.; Dalgarno, A.; Parkinson, W. H.

    1992-01-01

    The predissociation linewidths and level shifts of vibrational levels of three oxygen isotopic molecules (O2)-16, (O-16)(O-18), and (O2)-18 arising from the interactions of the B3Sigma(u)(-) state with the four repulsive states 5Pi(u), 3Sigma(u)(+), 3Pi(u), and 1Pi(u) have been calculated. A set of parameters characterizing these interactions has been determined. Good agreement between calculated and experimental predissociation widths and shifts has been obtained for all the three isotopic molecules.

  19. The production of CO(+) (B2Sigma +) from dissociative photoionization excitation of CO2

    NASA Astrophysics Data System (ADS)

    Wu, C. Y. R.; Judge, D. L.

    1986-04-01

    The dissociative photoionization excitation process in CO2 is studied. In contrast to previous studies, attention is focused on the vibrational and rotational levels produced in fragment ions, partial cross-section measurements for producing such fragment ions in a specific quantum state, and the mechanisms that govern the dissociative ionization excitation processes. The partial fluorescence cross section for the production of CO(+) (B2Sigma +) from CO2 over a wide wavelength range was measured. It is concluded that the production of the CO(+) (B2Sigma +) fragment near the threshold is through a direct dissociative photoionization process.

  20. The production of CO(+) (B2Sigma +) from dissociative photoionization excitation of CO2

    NASA Technical Reports Server (NTRS)

    Wu, C. Y. R.; Judge, D. L.

    1986-01-01

    The dissociative photoionization excitation process in CO2 is studied. In contrast to previous studies, attention is focused on the vibrational and rotational levels produced in fragment ions, partial cross-section measurements for producing such fragment ions in a specific quantum state, and the mechanisms that govern the dissociative ionization excitation processes. The partial fluorescence cross section for the production of CO(+) (B2Sigma +) from CO2 over a wide wavelength range was measured. It is concluded that the production of the CO(+) (B2Sigma +) fragment near the threshold is through a direct dissociative photoionization process.

  1. DYNAMICS OF PLANETARY SYSTEMS IN STAR CLUSTERS

    SciTech Connect

    Spurzem, R.; Giersz, M.; Heggie, D. C.; Lin, D. N. C.

    2009-05-20

    At least 10%-15% of nearby Sunlike stars have known Jupiter-mass planets. In contrast, very few planets are found in mature open and globular clusters such as the Hyades and 47 Tuc. We explore here the possibility that this dichotomy is due to the postformation disruption of planetary systems associated with the stellar encounters in long-lived clusters. One supporting piece of evidence for this scenario is the discovery of freely floating low-mass objects in star forming regions. We use two independent numerical approaches, a hybrid Monte Carlo and a direct N-body method, to simulate the impact of the encounters. We show that the results of numerical simulations are in reasonable agreement with analytical determinations in the adiabatic and impulsive limits. They indicate that distant stellar encounters generally do not significantly modify the compact and nearly circular orbits. However, moderately close stellar encounters, which are likely to occur in dense clusters, can excite planets' orbital eccentricity and induce dynamical instability in systems that are closely packed with multiple planets. The disruption of planetary systems occurs primarily through occasional nearly parabolic, nonadiabatic encounters, though eccentricity of the planets evolves through repeated hyperbolic adiabatic encounters that accumulate small-amplitude changes. The detached planets are generally retained by the potential of their host clusters as free floaters in young stellar clusters such as {sigma} Orionis. We compute effective cross sections for the dissolution of planetary systems and show that, for all initial eccentricities, dissolution occurs on timescales that are longer than the dispersion of small stellar associations, but shorter than the age of typical open and globular clusters. Although it is much more difficult to disrupt short-period planets, close encounters can excite modest eccentricity among them, such that subsequent tidal dissipation leads to orbital decay

  2. Hot Subluminous Stars

    NASA Astrophysics Data System (ADS)

    Heber, U.

    2016-08-01

    Hot subluminous stars of spectral type B and O are core helium-burning stars at the blue end of the horizontal branch or have evolved even beyond that stage. Most hot subdwarf stars are chemically highly peculiar and provide a laboratory to study diffusion processes that cause these anomalies. The most obvious anomaly lies with helium, which may be a trace element in the atmosphere of some stars (sdB, sdO) while it may be the dominant species in others (He-sdB, He-sdO). Strikingly, the distribution in the Hertzsprung-Russell diagram of He-rich versus He-poor hot subdwarf stars of the globular clusters ω Cen and NGC 2808 differ from that of their field counterparts. The metal-abundance patterns of hot subdwarfs are typically characterized by strong deficiencies of some lighter elements as well as large enrichments of heavy elements. A large fraction of sdB stars are found in close binaries with white dwarf or very low-mass main sequence companions, which must have gone through a common-envelope (CE) phase of evolution. Because the binaries are detached they provide a clean-cut laboratory to study this important but yet poorly understood phase of stellar evolution. Hot subdwarf binaries with sufficiently massive white dwarf companions are viable candidate progenitors of type Ia supernovae both in the double degenerate as well as in the single degenerate scenario as helium donors for double detonation supernovae. The hyper-velocity He-sdO star US 708 may be the surviving donor of such a double detonation supernova. Substellar companions to sdB stars have also been found. For HW Vir systems the companion mass distribution extends from the stellar into the brown dwarf regime. A giant planet to the acoustic-mode pulsator V391 Peg was the first discovery of a planet that survived the red giant evolution of its host star. Evidence for Earth-size planets to two pulsating sdB stars have been reported and circumbinary giant planets or brown dwarfs have been found around HW

  3. Hot Subluminous Stars

    NASA Astrophysics Data System (ADS)

    Heber, U.

    2016-08-01

    Hot subluminous stars of spectral type B and O are core helium-burning stars at the blue end of the horizontal branch or have evolved even beyond that stage. Most hot subdwarf stars are chemically highly peculiar and provide a laboratory to study diffusion processes that cause these anomalies. The most obvious anomaly lies with helium, which may be a trace element in the atmosphere of some stars (sdB, sdO) while it may be the dominant species in others (He-sdB, He-sdO). Strikingly, the distribution in the Hertzsprung–Russell diagram of He-rich versus He-poor hot subdwarf stars of the globular clusters ω Cen and NGC 2808 differ from that of their field counterparts. The metal-abundance patterns of hot subdwarfs are typically characterized by strong deficiencies of some lighter elements as well as large enrichments of heavy elements. A large fraction of sdB stars are found in close binaries with white dwarf or very low-mass main sequence companions, which must have gone through a common-envelope (CE) phase of evolution. Because the binaries are detached they provide a clean-cut laboratory to study this important but yet poorly understood phase of stellar evolution. Hot subdwarf binaries with sufficiently massive white dwarf companions are viable candidate progenitors of type Ia supernovae both in the double degenerate as well as in the single degenerate scenario as helium donors for double detonation supernovae. The hyper-velocity He-sdO star US 708 may be the surviving donor of such a double detonation supernova. Substellar companions to sdB stars have also been found. For HW Vir systems the companion mass distribution extends from the stellar into the brown dwarf regime. A giant planet to the acoustic-mode pulsator V391 Peg was the first discovery of a planet that survived the red giant evolution of its host star. Evidence for Earth-size planets to two pulsating sdB stars have been reported and circumbinary giant planets or brown dwarfs have been found around HW

  4. Kinematics of a Massive Star Cluster in Formation

    NASA Astrophysics Data System (ADS)

    Tan, Jonathan

    2014-10-01

    We propose to measure the proper motion stellar kinematics of a massive (~10^4Msun), forming proto-star-cluster to test basic theoretical models of formation. This will be the first time such a measurement has been performed. It requires HST-WFC3/IR and is beyond the practical capabilities of ground-based adaptive optics (AO) observations. In contrast to previously-studied massive, young (<10 Myr-old), already-formed clusters, such as NGC3603, Westerlund 1 or the Arches, our target protocluster, G286.21+0.17 (hereafter G286), is still gas-dominated and undergoing active star formation. It has been carefully selected from a complete survey of ~300 dense molecular gas clumps in a 120 sq. deg. region of the Galactic plane. The cluster is also relatively nearby (~2.5 kpc), but not too close that it would span a prohibitively large angular area or suffer from significant saturation problems. Such massive systems are rare and indeed we are unaware of any equivalent, early-stage (i.e., gas dominated) cluster that is closer. Given the depth of its gravitational potential based on its mass and size, the expected proper motions of many independent sub-clusters of stars are detectable at the ~5 sigma level over a 2-year baseline and global contraction of the cluster can be seen if it is happening even at just ~10% of the free-fall rate.

  5. THE COSMIC CORE-COLLAPSE SUPERNOVA RATE DOES NOT MATCH THE MASSIVE-STAR FORMATION RATE

    SciTech Connect

    Horiuchi, Shunsaku; Beacom, John F.; Kochanek, Christopher S.; Stanek, K. Z.; Thompson, Todd A.; Prieto, Jose L.

    2011-09-10

    We identify a 'supernova rate problem': the measured cosmic core-collapse supernova rate is a factor of {approx}2 smaller (with significance {approx}2{sigma}) than that predicted from the measured cosmic massive-star formation rate. The comparison is critical for topics from galaxy evolution and enrichment to the abundance of neutron stars and black holes. We systematically explore possible resolutions. The accuracy and precision of the star formation rate data and conversion to the supernova rate are well supported, and proposed changes would have far-reaching consequences. The dominant effect is likely that many supernovae are missed because they are either optically dim (low-luminosity) or dark, whether intrinsically or due to obscuration. We investigate supernovae too dim to have been discovered in cosmic surveys by a detailed study of all supernova discoveries in the local volume. If possible supernova impostors are included, then dim supernovae are common enough by fraction to solve the supernova rate problem. If they are not included, then the rate of dark core collapses is likely substantial. Other alternatives are that there are surprising changes in our understanding of star formation or supernova rates, including that supernovae form differently in small galaxies than in normal galaxies. These possibilities can be distinguished by upcoming supernova surveys, star formation measurements, searches for disappearing massive stars, and measurements of supernova neutrinos.

  6. Miniature wide field-of-view star trackers for spacecraft attitude sensing and navigation

    NASA Technical Reports Server (NTRS)

    Mccarty, William; Curtis, Eric; Hull, Anthony; Morgan, William

    1993-01-01

    Introducing a family of miniature, wide field-of-view star trackers for low cost, high performance spacecraft attitude determination and navigation applications. These devices, derivative of the WFOV Star Tracker Camera developed cooperatively by OCA Applied Optics and the Lawrence Livermore National Laboratory for the Brilliant Pebbles program, offer a suite of options addressing a wide range of spacecraft attitude measurement and control requirements. These sensors employ much wider fields than are customary (ranging between 20 and 60 degrees) to assure enough bright stars for quick and accurate attitude determinations without long integration intervals. The key benefit of this approach are light weight, low power, reduced data processing loads and high information carrier rates for wide ACS bandwidths. Devices described range from the proven OCA/LLNL WFOV Star Tracker Camera (a low-cost, space-qualified star-field imager utilizing the spacecraft's own computer and centroiding and position-finding), to a new autonomous subsystem design featuring dual-redundant cameras and completely self-contained star-field data processing with output quaternion solutions accurate to 100 micro-rad, 3 sigma, for stand-alone applications.

  7. Magnetic fields in A stars besides Ap stars

    NASA Astrophysics Data System (ADS)

    Kochukhov, O.

    2014-11-01

    I review ongoing efforts to understand the incidence of magnetism in intermediate-mass stars that are different from the magnetic Ap stars. This includes the search for magnetic fields in chemically peculiar stars of the Am and HgMn types as well as in normal A and late-B stars. I discuss different techniques for detecting weak stellar magnetic fields, and present a critical evaluation of recent magnetic detections in non-Ap stars. Special attention is given to the magnetic status of HgMn stars and to the discovery of weak polarization signatures in Sirius and Vega.

  8. Analysis of promoters controlled by the putative sigma factor AlgU regulating conversion to mucoidy in Pseudomonas aeruginosa: relationship to sigma E and stress response.

    PubMed Central

    Martin, D W; Schurr, M J; Yu, H; Deretic, V

    1994-01-01

    Alginate overproducition by mucoid Pseudomonas aeruginosa is a critical pathogenic determinant expressed by this organism during chronic infections in cystic fibrosis. Conversion to mucoidy and a subsequent loss of mucoid character can occur via different mutations in the algU mucA mucB gene cluster. The algU gene encodes a 22.2-kDa putative alternative sigma factor required for expression of the critical alginate biosynthetic gene algD. In this work, algU transcription was studied by S1 nuclease protection analysis. Transcription from the promoter proximal to the algU coding region was found to be dependent on AlgU. The -35 and -10 sequences of this newly mapped promoter showed strong similarity ot the promoters of two other critical alg genes: algD and algR. The proximal promoter of algR was also shown to depend on algU. Interestingly, the putative -35 and -10 regions of all three promoters displayed striking similarity to the consensus sequence of the sigma E-dependent promoters in Escherichia coli and Salmonella typhimurium. This 24-kDa sigma factor, controlling genes participating in resistance to high temperatures and oxidative stress, has been previously biochemically characterized, but the gene for sigma E remained unidentified. To examine whether AlgU is related to sigma E, the effect of algU inactivation on the sensitivity of P. aeruginosa to killing by heat and reactive oxygen intermediates was tested. Two isogenic pairs of algU+ and algU mutant strains were compared. The algU mutants, irrespective of the mucoid status of the parental strains, displayed increased sensitivity to killing by paraquat, known to generate intracellular superoxide radicals, and heat. Further lgobal homology searches revealed the presence of a previously unrecognized E. coli gene with the predicted gene product showing a striking 66% identity to AlgU. The corresponding gene from S. typhimurium was cloned and sequenced, and it is displayed one amino acid substitution relative to

  9. Life Cycle of Stars

    NASA Technical Reports Server (NTRS)

    1999-01-01

    In this stunning picture of the giant galactic nebula NGC 3603, the crisp resolution of NASA's Hubble Space Telescope captures various stages of the life cycle of stars in one single view. To the upper left of center is the evolved blue supergiant called Sher 25. The star has a unique circumstellar ring of glowing gas that is a galactic twin to the famous ring around the supernova 1987A. The grayish-bluish color of the ring and the bipolar outflows (blobs to the upper right and lower left of the star) indicates the presence of processed (chemically enriched) material. Near the center of the view is a so-called starburst cluster dominated by young, hot Wolf-Rayet stars and early O-type stars. A torrent of ionizing radiation and fast stellar winds from these massive stars has blown a large cavity around the cluster. The most spectacular evidence for the interaction of ionizing radiation with cold molecular-hydrogen cloud material are the giant gaseous pillars to the right of the cluster. These pillars are sculptured by the same physical processes as the famous pillars Hubble photographed in the M16 Eagle Nebula. Dark clouds at the upper right are so-called Bok globules, which are probably in an earlier stage of star formation. To the lower left of the cluster are two compact, tadpole-shaped emission nebulae. Similar structures were found by Hubble in Orion, and have been interpreted as gas and dust evaporation from possibly protoplanetary disks (proplyds). This true-color picture was taken on March 5, 1999 with the Wide Field Planetary Camera 2.

  10. Models of symbiotic stars

    NASA Technical Reports Server (NTRS)

    Friedjung, Michael

    1993-01-01

    One of the most important features of symbiotic stars is the coexistence of a cool spectral component that is apparently very similar to the spectrum of a cool giant, with at least one hot continuum, and emission lines from very different stages of ionization. The cool component dominates the infrared spectrum of S-type symbiotics; it tends to be veiled in this wavelength range by what appears to be excess emission in D-type symbiotics, this excess usually being attributed to circumstellar dust. The hot continuum (or continua) dominates the ultraviolet. X-rays have sometimes also been observed. Another important feature of symbiotic stars that needs to be explained is the variability. Different forms occur, some variability being periodic. This type of variability can, in a few cases, strongly suggest the presence of eclipses of a binary system. One of the most characteristic forms of variability is that characterizing the active phases. This basic form of variation is traditionally associated in the optical with the veiling of the cool spectrum and the disappearance of high-ionization emission lines, the latter progressively appearing (in classical cases, reappearing) later. Such spectral changes recall those of novae, but spectroscopic signatures of the high-ejection velocities observed for novae are not usually detected in symbiotic stars. However, the light curves of the 'symbiotic nova' subclass recall those of novae. We may also mention in this connection that radio observations (or, in a few cases, optical observations) of nebulae indicate ejection from symbiotic stars, with deviations from spherical symmetry. We shall give a historical overview of the proposed models for symbiotic stars and make a critical analysis in the light of the observations of symbiotic stars. We describe the empirical approach to models and use the observational data to diagnose the physical conditions in the symbiotics stars. Finally, we compare the results of this empirical

  11. TIMESCALES ON WHICH STAR FORMATION AFFECTS THE NEUTRAL INTERSTELLAR MEDIUM

    SciTech Connect

    Stilp, Adrienne M.; Dalcanton, Julianne J.; Weisz, Daniel R.; Williams, Benjamin F.; Warren, Steven R.; Skillman, Evan; Ott, Juergen; Dolphin, Andrew E.

    2013-08-01

    Turbulent neutral hydrogen (H I) line widths are often thought to be driven primarily by star formation (SF), but the timescale for converting SF energy to H I kinetic energy is unclear. As a complication, studies on the connection between H I line widths and SF in external galaxies often use broadband tracers for the SF rate, which must implicitly assume that SF histories (SFHs) have been constant over the timescale of the tracer. In this paper, we compare measures of H I energy to time-resolved SFHs in a number of nearby dwarf galaxies. We find that H I energy surface density is strongly correlated only with SF that occurred 30-40 Myr ago. This timescale corresponds to the approximate lifetime of the lowest mass supernova progenitors ({approx}8 M{sub Sun }). This analysis suggests that the coupling between SF and the neutral interstellar medium is strongest on this timescale, due either to an intrinsic delay between the release of the peak energy from SF or to the coherent effects of many supernova explosions during this interval. At {Sigma}{sub SFR} > 10{sup -3} M{sub Sun} yr{sup -1} kpc{sup -2}, we find a mean coupling efficiency between SF energy and H I energy of {epsilon} = 0.11 {+-} 0.04 using the 30-40 Myr timescale. However, unphysical efficiencies are required in lower {Sigma}{sub SFR} systems, implying that SF is not the primary driver of H I kinematics at {Sigma}{sub SFR} < 10{sup -3} M{sub Sun} yr{sup -1} kpc{sup -2}.

  12. Condensate dark matter stars

    SciTech Connect

    Li, X.Y.; Harko, T.; Cheng, K.S. E-mail: harko@hkucc.hku.hk

    2012-06-01

    We investigate the structure and stability properties of compact astrophysical objects that may be formed from the Bose-Einstein condensation of dark matter. Once the critical temperature of a boson gas is less than the critical temperature, a Bose-Einstein Condensation process can always take place during the cosmic history of the universe. Therefore we model the dark matter inside the star as a Bose-Einstein condensate. In the condensate dark matter star model, the dark matter equation of state can be described by a polytropic equation of state, with polytropic index equal to one. We derive the basic general relativistic equations describing the equilibrium structure of the condensate dark matter star with spherically symmetric static geometry. The structure equations of the condensate dark matter stars are studied numerically. The critical mass and radius of the dark matter star are given by M{sub crit} ≈ 2(l{sub a}/1fm){sup 1/2}(m{sub χ}/1 GeV){sup −3/2}M{sub s}un and R{sub crit} ≈ 1.1 × 10{sup 6}(l{sub a}/1 fm){sup 1/2}(m{sub χ}/1 GeV){sup −3/2} cm respectively, where l{sub a} and m{sub χ} are the scattering length and the mass of dark matter particle, respectively.

  13. Circulation of Stars

    NASA Astrophysics Data System (ADS)

    Boitani, P.

    2016-01-01

    Since the dawn of man, contemplation of the stars has been a primary impulse in human beings, who proliferated their knowledge of the stars all over the world. Aristotle sees this as the product of primeval and perennial “wonder” which gives rise to what we call science, philosophy, and poetry. Astronomy, astrology, and star art (painting, architecture, literature, and music) go hand in hand through millennia in all cultures of the planet (and all use catasterisms to explain certain phenomena). Some of these developments are independent of each other, i.e., they take place in one culture independently of others. Some, on the other hand, are the product of the “circulation of stars.” There are two ways of looking at this. One seeks out forms, the other concentrates on the passing of specific lore from one area to another through time. The former relies on archetypes (for instance, with catasterism), the latter constitutes a historical process. In this paper I present some of the surprising ways in which the circulation of stars has occurred—from East to West, from East to the Far East, and from West to East, at times simultaneously.

  14. Star Caught Smoking

    NASA Astrophysics Data System (ADS)

    2007-08-01

    VLTI Snapshots Dusty Puff Around Variable Star Using ESO's Very Large Telescope Interferometer, astronomers from France and Brazil have detected a huge cloud of dust around a star. This observation is further evidence for the theory that such stellar puffs are the cause of the repeated extreme dimming of the star. ESO PR Photo 34a/07 ESO PR Photo 34a/07 Dust Cloud in a R CrB Star (Artist's Impression) R Coronae Borealis stars are supergiants exhibiting erratic variability. Named after the first star that showed such behaviour [1], they are more than 50 times larger than our Sun. R Coronae Borealis stars can see their apparent brightness unpredictably decline to a thousandth of their nominal value within a few weeks, with the return to normal light levels being much slower. It has been accepted for decades that such fading could be due to obscuration of the stellar surface by newly formed dusty clouds. This 'Dust Puff Theory' suggests that mass is lost from the R Coronae Borealis (or R CrB for short) star and then moves away until the temperature is low enough for carbon dust to form. If the newly formed dust cloud is located along our line-of-sight, it eclipses the star. As the dust is blown away by the star's strong light, the 'curtain' vanishes and the star reappears. RY Sagittarii is the brightest member in the southern hemisphere of this family of weird stars. Located about 6,000 light-years away towards the constellation of Sagittarius (The Archer), its peculiar nature was discovered in 1895 by famous Dutch astronomer Jacobus Cornelius Kapteyn. In 2004, near-infrared adaptive optics observations made with NACO on ESO's Very Large Telescope allowed astronomers Patrick de Laverny and Djamel Mékarnia to clearly detect the presence of clouds around RY Sagittarii. This was the first direct confirmation of the standard scenario explaining the light variations of R CrB stars by the presence of heterogeneities in their envelope surrounding the star. ESO PR Photo 32e

  15. Nursery of New Stars

    NASA Technical Reports Server (NTRS)

    1995-01-01

    This is a Hubble Space Telescope image (right) of a vast nebula called NGC 604, which lies in the neighboring spiral galaxy M33, located 2.7 million light-years away in the constellation Triangulum. This is a site where new stars are being born in a spiral arm of the galaxy. Though such nebulae are common in galaxies, this one is particularly large, nearly 1,500 light-years across. The nebula is so vast it is easily seen in ground-based telescopic images (left). At the heart of NGC 604 are over 200 hot stars, much more massive than our Sun (15 to 60 solar masses). They heat the gaseous walls of the nebula making the gas fluoresce. Their light also highlights the nebula's three-dimensional shape, like a lantern in a cavern. By studying the physical structure of a giant nebula, astronomers may determine how clusters of massive stars affect the evolution of the interstellar medium of the galaxy. The nebula also yields clues to its star formation history and will improve understanding of the starburst process when a galaxy undergoes a 'firestorm' of star formation. The image was taken on January 17, 1995 with Hubble's Wide Field and Planetary Camera 2. Separate exposures were taken in different colors of light to study the physical properties of the hot gas (17,000 degrees Fahrenheit, 10,000 degrees Kelvin

  16. Origin of Neutron Stars

    NASA Astrophysics Data System (ADS)

    Brecher, K.

    1999-12-01

    The origin of the concept of neutron stars can be traced to two brief, incredibly insightful publications. Work on the earlier paper by Lev Landau (Phys. Z. Sowjetunion, 1, 285, 1932) actually predated the discovery of neutrons. Nonetheless, Landau arrived at the notion of a collapsed star with the density of a nucleus (really a "nucleus star") and demonstrated (at about the same time as, and independent of, Chandrasekhar) that there is an upper mass limit for dense stellar objects of about 1.5 solar masses. Perhaps even more remarkable is the abstract of a talk presented at the December 1933 meeting of the American Physical Society published by Walter Baade and Fritz Zwicky in 1934 (Phys. Rev. 45, 138). It followed the discovery of the neutron by just over a year. Their report, which was about the same length as the present abstract: (1) invented the concept and word supernova; (2) suggested that cosmic rays are produced by supernovae; and (3) in the authors own words, proposed "with all reserve ... the view that supernovae represent the transitions from ordinary stars to neutron stars (italics), which in their final stages consist of extremely closely packed neutrons." The abstract by Baade and Zwicky probably contains the highest density of new, important (and correct) ideas in high energy astrophysics ever published in a single paper. In this talk, we will discuss some of the facts and myths surrounding these two publications.

  17. Pulsational mode-typing in line profile variables. I - Four Beta Cephei stars

    NASA Technical Reports Server (NTRS)

    Campos, A. J.; Smith, M. A.

    1980-01-01

    The detailed variations of line profiles in the Beta Cephei-type variable stars Gamma Pegasi, Beta Cephei, Delta Ceti and Sigma Scorpii are modeled throughout their pulsation cycles in order to classify the dominant pulsation mode as radial or nonradial. High-dispersion Reticon observations of the variables were obtained for the Si III line at 4567 A, and line profiles broadened by radial or nonradial pulsations, rotation and radial-tangential macroturbulence were calculated based on a model atmosphere. It is found that only a radial pulsation mode can reproduce the radial velocity amplitude, changes in line asymmetry and uniform line width observed in all four stars. Results are in agreement with the color-to-light arguments of Stamford and Watson (1978), and suggest that radial pulsation plays the dominant role in the observed variations in most Beta Cephei stars. Evidence for shocks or moving shells is also found in visual line data for Sigma Scorpii and an ultraviolet line of Beta Cephei, together with evidence of smooth, secular period changes in Beta Cephei and Delta Ceti.

  18. Direct Observations of Sigma Phase Formation in Duplex Stainless Steels using In Situ Synchrotron X-Ray Diffraction

    SciTech Connect

    Elmer, J W; Palmer, T A; Specht, E D

    2006-07-03

    The formation and growth of sigma phase in 2205 duplex stainless steel was observed and measured in real time using synchrotron radiation during 10 hr isothermal heat treatments at temperatures between 700 C and 850 C. Sigma formed in near-equilibrium quantities during the isothermal holds, starting from a microstructure which contained a balanced mixture of metastable ferrite and austenite. In situ synchrotron diffraction continuously monitored the transformation, and these results were compared to those predicted by thermodynamic calculations. Differences between the calculated and measured amounts of sigma, ferrite and austenite suggest that the thermodynamic calculations underpredict the sigma dissolution temperature by approximately 50 C. The data were further analyzed using a modified Johnson-Mehl-Avrami (JMA) approach to determine kinetic parameters for sigma formation over this temperature range. The initial JMA exponent, n, at low fractions of sigma was found to be approximately 7.0, however, towards the end of the transformation, n decreased to values of approximately 0.75. The change in the JMA exponent was attributed to a change in the transformation mechanism from discontinuous precipitation with increasing nucleation rate, to growth of the existing sigma phase after nucleation site saturation occurred. Because of this change in mechanism, it was not possible to determine reliable values for the activation energy and pre-exponential terms for the JMA equation. While cooling back to room temperature, the partial transformation of austenite resulted in a substantial increase in the ferrite content, but sigma retained its high temperature value to room temperature.

  19. SigmaPlot 2000, Version 6.00, SPSS Inc. Computer Software Project Management, Requirements, and Design Document

    SciTech Connect

    HURLBUT, S.T.

    2000-10-24

    SigmaPlot is a vendor software product that will be used to convert the area under an absorbance curve generated by a Fourier transform infrared spectrometer (FTIR) to a relative area. SigmaPlot will be used in conjunction with procedure ZA-565-301, ''Determination of Moisture by Supercritical Fluid Extraction and Infrared Detection.''

  20. Separated Structure Functions for the Exclusive Electroproduction of K+Lambda and K+Sigma0 Final States

    SciTech Connect

    Pawel Ambrozewicz; Daniel Carman; Rob Feuerbach; Mac Mestayer; Brian Raue; Reinhard Schumacher; Avtandil Tkabladze

    2006-11-19

    We report measurements of the exclusive electroproduction of K{sup +}{Lambda} and K{sup +}{Sigma}{sup 0} final states from a proton target using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The separated structure functions {sigma}{sub T}, {sigma}{sub L},{sigma}{sub TT}, and {sigma}{sub LT} were extracted from the {Phi}- and {epsilon}-dependent differential cross sections taken with electron beam energies of 2.567, 4.056, and 4.247 GeV. This analysis represents the first {sigma}{sub L}/{sigma}{sub T} separation with the CLAS detector, and the first measurement of the kaon electroproduction structure functions away from parallel kinematics. The data span a broad range of momentum transfers from 0.5 {le} Q{sup 2} {le} 2.8 GeV{sup 2} and invariant energy from 1.6 {le} W {le} 2.4 GeV, while spanning nearly the full center-of-mass angular range of the kaon. The separated structure functions reveal clear differences between the production dynamics for the {Lambda} and {Sigma}{sup 0} hyperons. These results provide an unprecedented data sample with which to constrain current and future models for the associated production of strangeness, which will allow for a better understanding of the underlying resonant and non-resonant contributions to hyperon production.

  1. Effect of cold working and isothermal aging on the precipitation of sigma phase in 2205 duplex stainless steel

    SciTech Connect

    Cho, Hoon-Sung; Lee, Kwangmin

    2013-01-15

    A comprehensive understanding of the formation of the sigma phase resulting from the eutectoid reaction ({delta} {yields} {sigma} + {gamma}{sub 2}) is required. The kinetics necessary for the eutectoid reaction are closely related to the amount of plastic deformation in DSS. This work investigates the microstructural evolution of the {sigma} phase in a 22Cr-5Ni SAF 2205 DSS after subsequent plastic deformation and isothermal aging. The precipitation of the {sigma} phase resulted from the higher driving force for precipitating intermetallic compounds and the higher diffusion rate of their elements by cold-rolling, as well as the sufficient supply of molybdenum. The maximum amount of {sigma} phase precipitation remarkably increased with an increasing cold deformation, as compared with the non-cold-rolled materials. - Highlights: Black-Right-Pointing-Pointer The microstructural evolution of sigma phase has been characterized. Black-Right-Pointing-Pointer The chemical compositions of sigma phases were analyzed using TEM-EDX. Black-Right-Pointing-Pointer The effect of cold deformation on the precipitation of sigma phase was investigated.

  2. 77 FR 1491 - Sigma Corporation; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-10

    ... Sigma Corporation; Analysis of Proposed Consent Order To Aid Public Comment AGENCY: Federal Trade.... The attached Analysis to Aid Public Comment describes both the allegations in the draft complaint and... of thirty (30) days. The following Analysis to Aid Public Comment describes the terms of the...

  3. MODC2 procedures for assembly of MODCOMP-2 programs using the Sigma 5 assembler

    NASA Technical Reports Server (NTRS)

    Layland, J. W.

    1976-01-01

    A set of programs was written to enable the METASYMBOL macro-assembler of the Sigma 5 to assemble programs for an attached MODCOMP-2 minicomputer. This program set is a follow-on to previously developed program sets which facilitated assemblies for the PDP-11 and SDS-930.

  4. Sigma phase detection in duplex stainless steel by induced magnetic field

    NASA Astrophysics Data System (ADS)

    Silva, E. M.; Fialho, W. M. L.; Silva, H. F. B. M.; Leite, J. P.; Leite, J. P.; Oliveira, A. V. G.

    2016-07-01

    Duplex stainless steels when subjected to temperatures above 600 ° C have its tenacity decreased by the formation of sigma phase. This phase has high hardness and is rich in chromium and reduces the matrix of this element. In this study, field line density measurements, obtained in the reversibility region of magnetic domains, and application of artificial neural networks are used to monitor the formation of this undesirable phase. Samples of a stainless steel SAF 2205 were subjected to aging at temperatures of 800 ° C and 900 ° C, in order to obtain different amounts of sigma phase. The amount of this phase was obtained by image processing and the density of field lines through a Hall Effect sensor. Charpy impact tests were performed. The field lines densities were used for training of an artificial neural network and correlated with the presence of sigma phase and embrittlement of the material. The results showed that the method was able to correlate the parameters studied with the presence of the sigma phase and toughness of the material studied in both temperatures.

  5. Standalone engine simulator (SAES), Engine Dynamics simulator (EDS) Xerox Sigma 5 interface hardware manual

    NASA Technical Reports Server (NTRS)

    Kirshten, P. M.; Black, S.; Pearson, R.

    1979-01-01

    The ESS-EDS and EDS-Sigma interfaces within the standalone engine simulator are described. The operation of these interfaces, including the definition and use of special function signals and data flow paths within them during data transfers, is presented along with detailed schematics and circuit layouts of the described equipment.

  6. Infra-red lamp panel study and assessment application to thermal vacuum testing of sigma telescope

    NASA Technical Reports Server (NTRS)

    Mauduyt, Jacques; Merlet, Joseph; Poux, Christiane

    1986-01-01

    A research and development program of the Infra-Red Test has been conducted by the French Space Agency (CNES). A choice, after characterization, among several possibilities has been made on the type of methods and facilities for the I.R. test. An application to the Thermal Vacuum Test of the SIGMA Telescope is described.

  7. Successful Implementation of Six Sigma to Schedule Student Staffing for Circulation Service Desks

    ERIC Educational Resources Information Center

    Jankowski, Janiece

    2013-01-01

    In fall of 2011 the University at Buffalo Libraries circulation department undertook Six Sigma training for the purpose of overhauling its student scheduling process. The department was able to mitigate significant staffing budgetary reductions and resource reallocations and to overcome the unique challenges of scheduling student labor for a…

  8. ( sup 125 I)Iodoazidococaine, a photoaffinity label for the haloperidol-sensitive sigma receptor

    SciTech Connect

    Kahoun, J.R.; Ruoho, A.E. )

    1992-02-15

    A carrier-free radioiodinated cocaine photoaffinity label, (-)-3-({sup 125}I)iodo-4-azidococaine (({sup 125}I)IACoc), has been synthesized and used as a probe for cocaine-binding proteins. Photoaffinity labeling with 0.5 nM ({sup 125}I)IACoc resulted in selective derivatization of a 26-kDa polypeptide with the pharmacology of a sigma receptor in membranes derived from whole rat brain, rat liver, and human placenta. ({sup 125}I)IACoc labeling of the 26-kDa polypeptide was also inhibited by 10 {mu}M imipramine, amitriptyline, fluoxetine, benztropine, and tetrabenazine. The size of the ({sup 125}I)I-ACoc-labeled proteins is consistent with the size of proteins photolabeled in guinea pig brain and liver membranes by using the sigma photolabel azido-({sup 3}H)DTG. Kinetic analysis of ({sup 125}I)IACoc binding to rat liver microsomes revealed two sites with K{sub d} values of 19 and 126 pM, respectively. The presence or absence of proteolytic inhibitors during membrane preparation did not alter the size of the photolabeled sigma receptor, indicating that the 26-kDa polypeptide was not derived from a larger protein. In summary, ({sup 125}I)IACoc is a potent and highly specific photoaffinity label for the haloperidol-sensitive sigma receptor and will be useful for its biochemical and molecular characterization.

  9. Efficient optical design and measurement technique to six sigma laser processing

    NASA Astrophysics Data System (ADS)

    Scaggs, Michael; Haas, Gil

    2014-03-01

    A six sigma laser processing system is proposed that utilizes real time measurement of ISO 11146 and ISO 13694 laser beam parameters without disrupting the process beam and with minimal loss. If key laser beam parameters can be measured during a laser process, without a disruption to the process, then a higher level of process control can be realized. The difficulty in achieving this concept to date is that most accepted beam measurement techniques are time averaged and require interruption of the laser beam and therefore have made it impractical for real time measurement which is necessary to consider six sigma process control. Utilizing an all passive optical technique to measure a laser's beam waist and other parameters for both focused and unfocused beams, the direct measurement of the ISO laser beam parameters are realized without disruption to the process and with minimal loss. The technique is simple enough to be applied to low and high power systems well into the multi-kilowatt range. Through careful monitoring of all laser beam parameters via software control of upper and lower limits for these parameters, tighter quality control is possible for achieving a six sigma process. In this paper we describe the optical design for both low and high power laser systems and how six sigma laser processing may be realized.

  10. Learning through Publishing "The Pi Sigma Alpha Undergraduate Journal of Politics"

    ERIC Educational Resources Information Center

    Bauer, Benjamin J.; Ogas, Whitney C.; Shakir, Omar R.; Oxley, Zoe M.; Clawson, Rosalee A.

    2009-01-01

    Publishing a research journal can be a rewarding and useful learning experience for undergraduate students. Drawing upon our experiences with "The Pi Sigma Alpha Undergraduate Journal of Politics," we describe the benefits of producing a peer-reviewed journal. Among the benefits we highlight are gains in political science knowledge, increased…

  11. Transforming the patient care environment with Lean Six Sigma and realistic evaluation.

    PubMed

    Black, Jason

    2009-01-01

    Lean Six Sigma (LSS) is a structured methodology for transforming processes, but it does not fully consider the complex social interactions that cause processes to form in hospital organizations. By combining LSS implementations with the concept of Realistic Evaluation, a methodology that promotes change by assessing and considering the individual characteristics of an organization's social environment, successful and sustainable process improvement is more likely.

  12. Applying Lean Six Sigma for innovative change to the post-anesthesia care unit.

    PubMed

    Haenke, Roger; Stichler, Jaynelle F

    2015-04-01

    Many healthcare organizations are building or renovating patient care facilities. Using Lean Six Sigma methods, nurse leaders can eliminate unnecessary waste and improve work and patient care environments. Starting with a key department like the post-anesthesia care unit is a good way to expose staff and leaders to the potential of Lean.

  13. SIGMA: A Knowledge-Based Simulation Tool Applied to Ecosystem Modeling

    NASA Technical Reports Server (NTRS)

    Dungan, Jennifer L.; Keller, Richard; Lawless, James G. (Technical Monitor)

    1994-01-01

    The need for better technology to facilitate building, sharing and reusing models is generally recognized within the ecosystem modeling community. The Scientists' Intelligent Graphical Modelling Assistant (SIGMA) creates an environment for model building, sharing and reuse which provides an alternative to more conventional approaches which too often yield poorly documented, awkwardly structured model code. The SIGMA interface presents the user a list of model quantities which can be selected for computation. Equations to calculate the model quantities may be chosen from an existing library of ecosystem modeling equations, or built using a specialized equation editor. Inputs for dim equations may be supplied by data or by calculation from other equations. Each variable and equation is expressed using ecological terminology and scientific units, and is documented with explanatory descriptions and optional literature citations. Automatic scientific unit conversion is supported and only physically-consistent equations are accepted by the system. The system uses knowledge-based semantic conditions to decide which equations in its library make sense to apply in a given situation, and supplies these to the user for selection. "Me equations and variables are graphically represented as a flow diagram which provides a complete summary of the model. Forest-BGC, a stand-level model that simulates photosynthesis and evapo-transpiration for conifer canopies, was originally implemented in Fortran and subsequenty re-implemented using SIGMA. The SIGMA version reproduces daily results and also provides a knowledge base which greatly facilitates inspection, modification and extension of Forest-BGC.

  14. Beam asymmetry {Sigma} measurements of {pi}{sup -} photoproduction on neutrons

    SciTech Connect

    Mandaglio, G.; Manganaro, M.; Giardina, G.; Mammoliti, F.; Bellini, V.; Giusa, A.; Randieri, C.; Russo, G.; Sperduto, M. L.; Bocquet, J. P.; Lleres, A.; Rebreyend, D.; D'Angelo, A.; Fantini, A.; Franco, D.; Schaerf, C.; Vegna, V.

    2010-10-15

    The -beam asymmetry {Sigma} in the photoproduction of negative pions on quasi-free neutrons in a deuterium target was measured at the Grenoble Anneau Accelerateur Laser in the energy interval 700-1500 MeV and over a wide angular range, using polarized and tagged photons. Results are compared with recent partial-wave analyses.

  15. 78 FR 12102 - Manufacturer of Controlled Substances; Notice of Application; Sigma Aldrich Research Biochemicals...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-21

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF JUSTICE Drug Enforcement Administration Manufacturer of Controlled Substances; Notice of Application; Sigma Aldrich Research Biochemicals, Inc. Pursuant to Sec. 1301.33(a), Title 21 of the Code of Federal Regulations (CFR), this is notice that on November 21,...

  16. Kaon condensation in the linear sigma model at finite density and temperature

    SciTech Connect

    Tran Huu Phat; Nguyen Van Long; Nguyen Tuan Anh; Le Viet Hoa

    2008-11-15

    Basing on the Cornwall-Jackiw-Tomboulis effective action approach we formulate a theoretical formalism for studying kaon condensation in the linear sigma model at finite density and temperature. We derive the renormalized effective potential in the Hartree-Fock approximation, which preserves the Goldstone theorem. This quantity is then used to consider physical properties of kaon matter.

  17. Chi Sigma Iota Chapter Leadership and Professional Identity Development in Early Career Counselors

    ERIC Educational Resources Information Center

    Luke, Melissa; Goodrich, Kristopher M.

    2010-01-01

    As the academic and professional honor society of counseling, Chi Sigma Iota (CSI) has been recognized in developing advocacy, leadership, and professional identity in student and professional members. A qualitative, grounded theory study was conducted to investigate experiences of 15 early career counselors who were CSI chapter leaders as…

  18. Molecular mechanisms involving sigma receptor-mediated induction of MCP-1: implication for increased monocyte transmigration.

    PubMed

    Yao, Honghong; Yang, Yanjing; Kim, Kee Jun; Bethel-Brown, Crystal; Gong, Nan; Funa, Keiko; Gendelman, Howard E; Su, Tsung-Ping; Wang, John Q; Buch, Shilpa

    2010-06-10

    Cocaine abuse hastens the neurodegeneration often associated with advanced HIV-1 infection. The mechanisms, in part, revolve around the neuroinflammatory processes mediated by the chemokine monocyte chemotactic protein-1 (MCP-1/CCL2). Understanding factors that modulate MCP-1 and, in turn, facilitate monocyte extravasation in the brain is thus of paramount importance. We now demonstrate that cocaine induces MCP-1 in rodent microglia through translocation of the sigma receptor to the lipid raft microdomains of the plasma membrane. Sequential activation of Src, mitogen-activated protein kinases (MAPKs), and phosphatidylinositol-3' kinase (PI3K)/Akt and nuclear factor kappaB (NF-kappaB) pathways resulted in increased MCP-1 expression. Furthermore, conditioned media from cocaine-exposed microglia increased monocyte transmigration, and thus was blocked by antagonists for CCR2 or sigma receptor. These findings were corroborated by demonstrating increased monocyte transmigration in mice exposed to cocaine, which was attenuated by pretreatment of mice with the sigma receptor antagonist. Interestingly, cocaine-mediated transmigratory effects were not observed in CCR2 knockout mice. We conclude that cocaine-mediated induction of MCP-1 accelerates monocyte extravasation across the endothelium. Understanding the regulation of MCP-1 expression and functional changes by cocaine/sigma receptor system may provide insights into the development of potential therapeutic targets for HIV-1-associated neurocognitive disorders. PMID:20354174

  19. Design Principles of A Sigma-delta Flux-gate Magnetometer

    NASA Astrophysics Data System (ADS)

    Magnes, W.; Valavanoglou, A.; Pierce, D.; Frank, A.; Schwingenschuh, K.

    A state-of-the-art flux-gate magnetometer is characterised by magnetic field resolution of several pT in a wide frequency range, low power consumption, low weight and high robustness. Therefore, flux-gate magnetometers are frequently used for ground-based Earth's field observation as well as for measurements aboard scientific space missions. But both traditional analogue and recently developed digital flux-gate magnetometers need low power and high-resolution analogue-to-digital converters for signal quan- tization. The disadvantage of such converters is the low radiation hardness. This fact has led to the idea of combining a traditional analogue flux-gate regulation circuit with that of a discretely realized sigma-delta converter in order to get a radiation hard and further miniaturized magnetometer. The name sigma-delta converter is derived from putting an integrator in front of a 1-bit delta modulator which forms the sigma-delta loop. It is followed by a digital decimation filter realized in a field-programmable gate array (FPGA). The flux-gate regulation and the sigma-delta loop are quite similar in the way of realizing the integrator and feedback circuit, which makes it easy to com- bine these two systems. The presented talk deals with the design principles and the results of a first bread board model.

  20. The Application of Six Sigma Methodologies to University Processes: The Use of Student Teams

    ERIC Educational Resources Information Center

    Pryor, Mildred Golden; Alexander, Christine; Taneja, Sonia; Tirumalasetty, Sowmya; Chadalavada, Deepthi

    2012-01-01

    The first student Six Sigma team (activated under a QEP Process Sub-team) evaluated the course and curriculum approval process. The goal was to streamline the process and thereby shorten process cycle time and reduce confusion about how the process works. Members of this team developed flowcharts on how the process is supposed to work (by…