Science.gov

Sample records for helium-strong star sigma

  1. DISCOVERY OF ROTATIONAL BRAKING IN THE MAGNETIC HELIUM-STRONG STAR SIGMA ORIONIS E

    SciTech Connect

    Townsend, R. H. D.; Oksala, M. E.; Owocki, S. P.; Cohen, D. H.; Ud-Doula, A.

    2010-05-10

    We present new U-band photometry of the magnetic helium-strong star {sigma} Ori E, obtained over 2004-2009 using the SMARTS 0.9 m telescope at Cerro Tololo Inter-American Observatory. When combined with historical measurements, these data constrain the evolution of the star's 1.19 day rotation period over the past three decades. We are able to rule out a constant period at the p {sub null} = 0.05% level, and instead find that the data are well described (p {sub null} = 99.3%) by a period increasing linearly at a rate of 77 ms per year. This corresponds to a characteristic spin-down time of 1.34 Myr, in good agreement with theoretical predictions based on magnetohydrodynamical simulations of angular momentum loss from magnetic massive stars. We therefore conclude that the observations are consistent with {sigma} Ori E undergoing rotational braking due to its magnetized line-driven wind.

  2. Exploring the photometric signatures of magnetospheres around helium-strong stars

    NASA Astrophysics Data System (ADS)

    Townsend, R. H. D.

    2008-09-01

    Photometric variations due to magnetically confined material around helium-strong stars are investigated within the framework of the rigidly rotating magnetosphere model. For dipole field topologies, the model is used to explore how the morphology of light curves evolves in response to changes to the observer inclination, magnetic obliquity, rotation rate and optical depth. The general result is that double-minimum light curves arise when the obliquity and/or inclination are close to 90° no light variations are seen in the opposite limit. For intermediate cases, single-minimum light curves occur. These findings are interpreted with the aid of a simple, analytical torus model, paving the way for the development of new photometric-based constraints on the fundamental parameters of helium-strong stars. Illustrative applications to five stars in the class are presented.

  3. The discovery of nonthermal radio emission from magnetic Bp-Ap stars

    NASA Technical Reports Server (NTRS)

    Drake, Stephen A.; Abbott, David C.; Bastian, T. S.; Bieging, J. H.; Churchwell, E.

    1987-01-01

    In a VLA survey of chemically peculiar B- and A-type stars with strong magnetic fields, five of the 34 stars observed have been identified as 6 cm continuum sources. Three of the detections are helium-strong early Bp stars (Sigma Ori E, HR 1890, and Delta Ori C), and two are helium weak, silicon-strong stars with spectral types near A0p (IQ Aur = HD 34452, Babcock's star = HD 215441). The 6 cm luminosities L6 (ergs/s Hz) range from log L6 = 16.2 to 17.9, somewhat less than the OB supergiants and W-R stars. Three-frequency observations indicate that the helium-strong Bp stars are variable nonthermal sources.

  4. X-RAY VARIABILITY OF {sigma} ORIONIS YOUNG STARS AS OBSERVED WITH ROSAT

    SciTech Connect

    Caballero, J. A.; Lopez-Santiago, J.; De Castro, E.; Cornide, M.

    2009-06-15

    We used the Aladin Virtual Observatory tool and High Resolution Imager ROSAT archival data to search for X-ray variability in scale of days in 23 young stars in the {sigma} Orionis cluster and a background galaxy. Five stars displayed unambiguous flares and had probabilities p {sub var}>> 99% of being actual variables. Two of the detected flares were violent and long lasting, with maximum duration of six days and amplitude of eight times above the quiescent level. We classified another four stars as possible X-ray variables, including the binary system formed by the B2Vp star {sigma} Ori E and its close late-type companion. This makes a minimum frequency of high-amplitude X-ray variability in excess of a day of 39% among {sigma} Orionis stars. The incidence of this kind of X-ray variability seems to be lower among classical T Tauri stars with mid-infrared flux excesses than among fast-rotating, disk-less young stars.

  5. 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).

  6. 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.

  7. 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

    2000-10-06

    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.

  8. 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

  9. 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.

  10. 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.

  11. Coronal activity in F-, G-, and K-type stars. III - The coronal differential emission measure distribution of Capella, Sigma-squared CrB, and Procyon

    NASA Technical Reports Server (NTRS)

    Lemen, J. R.; Mewe, R.; Schrijver, C. J.; Fludra, A.

    1989-01-01

    EXOSAT soft X-ray spectra of three binary systems of cool stars are analyzed: Capella (G6 III + F9 III), Sigma-squared CrB (F8 V + G1 V), and Procyon (F5 IV-V + DF). The EXOSAT transmission grating spectrometer permits the study of individual spectral lines and line complexes between 10 and 200 A with approximately 3 A resolution. First it is demonstrated that the spectra can be described reasonably well by a two-temperature model corona. Then the assumption that only two temperatures exist in the stellar coronas is relaxed and differential emission measure distributions are derived from the three spectra. The results from the multithermal modeling are consistent with those of the two-temperature models: emission from the coronas of each of the three stars is dominated by plasma in two relative narrow temperature intervals. These intervals are centered on 5 MK and 25 MK in the cases of Capella and Sigma-squared CrB, and 0.6 MK and 3 MK in the case of Procyon. The implications of the results for the structure of stellar coronas are briefly discussed.

  12. Coronal activity in F-, G-, and K-type stars. III. The coronal differential emission measure distribution of Capella, Sigma-squared CrB, and Procyon

    SciTech Connect

    Lemen, J.R.; Mewe, R.; Schrijver, C.J.; Fludra, A.; SRON, Laboratorium voor Ruimteonderzoek, Utrecht; Joint Institute for Laboratory Astrophysics, Boulder, CO; Wroclaw, Uniwersytet )

    1989-06-01

    EXOSAT soft X-ray spectra of three binary systems of cool stars are analyzed: Capella (G6 III + F9 III), Sigma-squared CrB (F8 V + G1 V), and Procyon (F5 IV-V + DF). The EXOSAT transmission grating spectrometer permits the study of individual spectral lines and line complexes between 10 and 200 A with approximately 3 A resolution. First it is demonstrated that the spectra can be described reasonably well by a two-temperature model corona. Then the assumption that only two temperatures exist in the stellar coronas is relaxed and differential emission measure distributions are derived from the three spectra. The results from the multithermal modeling are consistent with those of the two-temperature models: emission from the coronas of each of the three stars is dominated by plasma in two relative narrow temperature intervals. These intervals are centered on 5 MK and 25 MK in the cases of Capella and Sigma-squared CrB, and 0.6 MK and 3 MK in the case of Procyon. The implications of the results for the structure of stellar coronas are briefly discussed. 41 refs.

  13. Coronal activity in F-, G-, and K-type stars. III - The coronal differential emission measure distribution of Capella, Sigma-squared CrB, and Procyon

    NASA Technical Reports Server (NTRS)

    Lemen, J. R.; Mewe, R.; Schrijver, C. J.; Fludra, A.

    1989-01-01

    EXOSAT soft X-ray spectra of three binary systems of cool stars are analyzed: Capella (G6 III + F9 III), Sigma-squared CrB (F8 V + G1 V), and Procyon (F5 IV-V + DF). The EXOSAT transmission grating spectrometer permits the study of individual spectral lines and line complexes between 10 and 200 A with approximately 3 A resolution. First it is demonstrated that the spectra can be described reasonably well by a two-temperature model corona. Then the assumption that only two temperatures exist in the stellar coronas is relaxed and differential emission measure distributions are derived from the three spectra. The results from the multithermal modeling are consistent with those of the two-temperature models: emission from the coronas of each of the three stars is dominated by plasma in two relative narrow temperature intervals. These intervals are centered on 5 MK and 25 MK in the cases of Capella and Sigma-squared CrB, and 0.6 MK and 3 MK in the case of Procyon. The implications of the results for the structure of stellar coronas are briefly discussed.

  14. Effects of the {{\\boldsymbol{\\sigma }}}^{{\\boldsymbol{* }}} and ϕ Mesons on the Properties of Massive Protoneutron Stars

    NASA Astrophysics Data System (ADS)

    Mu, Xueling; Jia, Huanyu; Zhou, Xia; Wang, Hui

    2017-09-01

    The properties of massive neutron stars and protoneutron stars are studied in this work in the framework of relativistic mean-field theory. For certain choices of coupling parameters, a two-solar mass cold neutron star is obtained in the presence of hyperons, taking into account the influence of {σ }* and ϕ mesons. The model for the coupling parameters is then extrapolated to study the effects of {σ }* and ϕ mesons on the properties of massive protoneutron stars in different evolutionary stages. The coupling constants are determined by two different methods, and their corresponding influence on the equation of state, mass, radius, and temperature is studied. The effect of the strange mesons is different at different evolution stages of the neutron star. The properties of a protoneutron star corresponding to the mass of PSR J0348+0432 are also presented.

  15. 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.

  16. 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).

  17. Sigma Filter

    NASA Technical Reports Server (NTRS)

    Balgovind, R. C.

    1985-01-01

    The GLA Fourth-Order model is needed to smooth the topography. This is to remove the Gibbs phenomenon. The Gibbs phenomenon occurs whenever we truncate a Fourier Series. The Sigma factors were introduced to reduce the Gibbs phenomenon. It is found that the smooth Fourier series is nothing but the original Fourier series with its coefficients multiplied by corresponding sigma factors. This operator can be applied many times to obtain high order sigma filtered field and is easily applicable using FFT. It is found that this filter is beneficial in deriving the topography.

  18. 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.

  19. lambda. and. sigma. hypernuclei

    SciTech Connect

    Millener, D.J.

    1985-01-01

    The present status of structure calculations for p-shell ..lambda.. hypernuclei, including the phenomenological determination of ..lambda..N effective interaction matrix elements, is briefly reviewed. For ..sigma.. hypernuclei the Nijmegen potential model D is used for guidance in constructing ..sigma..N effective interactions. The structure of /sub ..sigma..//sup 12/Be and /sub ..sigma..//sup 12/C, including isospin mixing in the later case, is discussed, and a comparison is made with experimental data. 19 refs., 5 figs., 4 tabs.

  20. Six Sigma in Education

    ERIC Educational Resources Information Center

    LeMahieu, Paul G.; Nordstrum, Lee E.; Cudney, Elizabeth A.

    2017-01-01

    Purpose: This paper is one of seven in this volume that aims to elaborate different approaches to quality improvement in education. It delineates a methodology called Six Sigma. Design/methodology/approach: The paper presents the origins, theoretical foundations, core principles and a case study demonstrating an application of Six Sigma in a…

  1. Six Sigma in Education

    ERIC Educational Resources Information Center

    LeMahieu, Paul G.; Nordstrum, Lee E.; Cudney, Elizabeth A.

    2017-01-01

    Purpose: This paper is one of seven in this volume that aims to elaborate different approaches to quality improvement in education. It delineates a methodology called Six Sigma. Design/methodology/approach: The paper presents the origins, theoretical foundations, core principles and a case study demonstrating an application of Six Sigma in a…

  2. Sigma Receptor Binding Assays.

    PubMed

    Chu, Uyen B; Ruoho, Arnold E

    2015-12-08

    Sigma receptors, both Sigma-1(S1R) and Sigma-2 (S2R), are small molecule-regulated, primarily endoplasmic reticulum (ER) membrane-associated sites. A number of drugs bind to sigma receptors, including the antipsychotic haloperidol and (+)-pentazocine, an opioid analgesic. Sigma receptors are implicated in many central nervous system disorders, in particular Alzheimer's disease and conditions associated with motor control, such as Amyotrophic Lateral Sclerosis (ALS). Described in this unit are radioligand binding assays used for the pharmacological characterization of S1R and S2R. Methods detailed include a radioligand saturation binding assay for defining receptor densities and a competitive inhibition binding assay employing [³H]-(+)-pentazocine for identifying and characterizing novel ligands that interact with S1R. Procedures using [³H]-1,3-di(2-tolyl)guanidine ([³H]-DTG), a nonselective sigma receptor ligand, are described for conducting a saturation binding and competitive inhibition assays for the S2R site. These protocols are of value in drug discovery in identifying new sigma ligands and in the characterization of these receptors.

  3. 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.

  4. Sigma factors in Pseudomonas aeruginosa.

    PubMed

    Potvin, Eric; Sanschagrin, François; Levesque, Roger C

    2008-01-01

    In Pseudomonas aeruginosa, as in most bacterial species, the expression of genes is tightly controlled by a repertoire of transcriptional regulators, particularly the so-called sigma (sigma) factors. The basic understanding of these proteins in bacteria has initially been described in Escherichia coli where seven sigma factors are involved in core RNA polymerase interactions and promoter recognition. Now, 7 years have passed since the completion of the first genome sequence of the opportunistic pathogen P. aeruginosa. Information from the genome of P. aeruginosa PAO1 identified 550 transcriptional regulators and 24 putative sigma factors. Of the 24 sigma, 19 were of extracytoplasmic function (ECF). Here, basic knowledge of sigma and ECF proteins was reviewed with particular emphasis on their role in P. aeruginosa global gene regulation. Summarized data are obtained from in silico analysis of P. aeruginosasigma and ECF including rpoD (sigma(70)), RpoH (sigma(32)), RpoF (FliA or sigma(28)), RpoS (sigma(S) or sigma(38)), RpoN (NtrA, sigma(54) or sigma(N)), ECF including AlgU (RpoE or sigma(22)), PvdS, SigX and a collection of uncharacterized sigma ECF, some of which are implicated in iron transport. Coupled to systems biology, identification and functional genomics analysis of P. aeruginosasigma and ECF are expected to provide new means to prevent infection, new targets for antimicrobial therapy, as well as new insights into the infection process.

  5. SIGMA RECEPTOR BINDING ASSAYS

    PubMed Central

    CHU, UYEN B.; RUOHO, ARNOLD E.

    2016-01-01

    Sigma receptors belong to a class of small molecule-regulated, primarily endoplasmic reticulum (ER) membrane-associated receptors, of which there are two subtypes: the Sigma-1 receptor (S1R) and the Sigma-2 receptor (S2R). Both S1R and S2R bind to a number of drugs including antipsychotic, haloperidol, and the opioid analgesic, (+)-pentazocine. Sigma receptors are implicated in multiple disease pathologies associated with the nervous system including diseases affecting motor control such as Amyotrophic Lateral Sclerosis (ALS) and Alzeimher's disease. This unit describes methods for the pharmacological characterization of S1R and S2R using radioligand-binding assays. In the first section, radioligand saturation binding assay to determine receptor densities and competitive inhibition assays to characterize affinities of novel compounds are presented for S1R using the selective S1R ligand, [3H]-(+)-pentazocine. The second section describes radioligand saturation binding assay and competitive inhibition assays for the S2R using a non-selective S1R and S2R ligand, [3H]-1,3-di(2-tolyl)guanidine ([3H]-DTG). PMID:26646191

  6. The nucleon sigma term

    SciTech Connect

    Banerjee, S; Tandy, P.C.

    1995-04-01

    The explicit chiral symmetry breaking component of the nucleon mass generated by the bare quark mass is extracted from a mean field treatment of chiral meson modes produced by a QCD-based model field theory. Because of the underlying finite range gluon propagator, bosonization produces a distributed dynamics of dressed quarks and finite size chiral meson fields that is totally determined by the amplitude functions of the quark propagator. The authors take the latter from a recent confining representation constrained by soft chiral meson physics. The sigma term is generated consistently from that level. A hedgehog format facilitates the mean field solution. New contributions to the sigma term arise which are not present in the point-coupling limit and the resulting value will be presented.

  7. 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.

  8. 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.

  9. Extended Chiral ({sigma},{pi},{omega}) Mean-Field Model with Vacuum Fluctuation Corrections

    SciTech Connect

    Uechi, Schun T.; Uechi, Hiroshi

    2011-10-21

    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}) mean-field theory. The chiral nonlinear ({sigma},{pi},{omega}) mean-field theory is an extension of the conserving nonlinear (nonchiral){sigma}-{omega} mean-field theory, which is thermodynamically consistent, relativistic and Lorentz-covariant. In the extended chiral ({sigma},{pi},{omega}) mean-field model, all the masses of hadrons are produced by the spontaneous chiral symmetry breaking, which is different from 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.

  10. 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; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, I; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Cilijak, M; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Coca, M; Compostella, G; Convery, M E; Conway, J; Cooper, B; Copic, K; Cordelli, M; Cortiana, G; Crescioli, F; Cuenca Almenar, C; Cuevas, J; Culbertson, R; Cully, J C; DaRonco, S; Datta, M; D'Auria, S; Davies, T; Dagenhart, D; de Barbaro, P; De Cecco, S; Deisher, A; De Lentdecker, G; De Lorenzo, G; Dell'Orso, M; Delli Paoli, F; Demortier, L; Deng, J; Deninno, M; De Pedis, D; Derwent, P F; Di Giovanni, G P; Dionisi, C; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Dörr, C; Donati, S; Dong, P; Donini, J; Dorigo, T; Dube, S; Efron, J; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, I; Fedorko, W T; Feild, R G; Feindt, M; Fernandez, J P; Field, R; Flanagan, G; Forrest, R; Forrester, S; 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.

  11. 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.

  12. Manage your human sigma.

    PubMed

    Fleming, John H; Coffman, Curt; Harter, James K

    2005-01-01

    If sales and service organizations are to improve, they must learn to measure and manage the quality of the employee-customer encounter. Quality improvement methodologies such as Six Sigma are extremely useful in manufacturing contexts, but they're less useful when it comes to human interactions. To address this problem, the authors have developed a quality improvement approach they refer to as Human Sigma. It weaves together a consistent method for assessing the employee-customer encounter and a disciplined process for managing and improving it. There are several core principles for measuring and managing the employee-customer encounter: It's important not to think like an economist or an engineer when assessing interactions because emotions inform both sides' judgments and behavior. The employee-customer encounter must be measured and managed locally, because there are enormous variations in quality at the work-group and individual levels. And to improve the quality of the employee-customer interaction, organizations must conduct both short-term, transactional interventions and long-term, transformational ones. Employee engagement and customer engagement are intimately connected--and, taken together, they have an outsized effect on financial performance. They therefore need to be managed holistically. That is, the responsibility for measuring and monitoring the health of employee-customer relationships must reside within a single organizational structure, with an executive champion who has the authority to initiate and manage change. Nevertheless, the local manager remains the single most important factor in local group performance. A local manager whose work group shows suboptimal performance should be encouraged to conduct interventions, such as targeted training, performance reviews, action learning, and individual coaching.

  13. 77 FR 1491 - Sigma Corporation; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-10

    ... information, like anyone's Social Security number, date of birth, driver's license number or other state... available. Sigma and its largest competitors in the DIPF market, McWane, Inc. (``McWane'') and Star Pipe Products Ltd. (``Star''), all sell imported DIPF. McWane was the only domestic producer of a full line...

  14. Six sigma for revenue retrieval.

    PubMed

    Plonien, Cynthia

    2013-01-01

    Deficiencies in revenue retrieval due to failures in obtaining charges have contributed to a negative bottom line for numerous hospitals. Improving documentation practices through a Six Sigma process improvement initiative can minimize opportunities for errors through reviews and instill structure for compliance and consistency. Commitment to the Six Sigma principles with continuous monitoring of outcomes and constant communication of results to departments, management, and payers is a strong approach to reducing the financial impact of denials on an organization's revenues and expenses. Using Six Sigma tools can help improve the organization's financial performance not only for today, but also for health care's uncertain future.

  15. 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…

  16. Dirac sigma models from gauging

    NASA Astrophysics Data System (ADS)

    Salnikov, Vladimir; Strobl, Thomas

    2013-11-01

    The G/G WZW model results from the WZW-model by a standard procedure of gauging. G/G WZW models are members of Dirac sigma models, which also contain twisted Poisson sigma models as other examples. We show how the general class of Dirac sigma models can be obtained from a gauging procedure adapted to Lie algebroids in the form of an equivariantly closed extension. The rigid gauge groups are generically infinite dimensional and a standard gauging procedure would give a likewise infinite number of 1-form gauge fields; the proposed construction yields the requested finite number of them. Although physics terminology is used, the presentation is kept accessible also for a mathematical audience.

  17. Six Sigma in healthcare delivery.

    PubMed

    Liberatore, Matthew J

    2013-01-01

    The purpose of this paper is to conduct a comprehensive review and assessment of the extant Six Sigma healthcare literature, focusing on: application, process changes initiated and outcomes, including improvements in process metrics, cost and revenue. Data were obtained from an extensive literature search. Healthcare Six Sigma applications were categorized by functional area and department, key process metric, cost savings and revenue generation (if any) and other key implementation characteristics. Several inpatient care areas have seen most applications, including admission, discharge, medication administration, operating room (OR), cardiac and intensive care. About 42.1 percent of the applications have error rate as their driving metric, with the remainder focusing on process time (38 percent) and productivity (18.9 percent). While 67 percent had initial improvement in the key process metric, only 10 percent reported sustained improvement. Only 28 percent reported cost savings and 8 percent offered revenue enhancement. These results do not favorably assess Six Sigma's overall effectiveness and the value it offers healthcare. Results are based on reported applications. Future research can include directly surveying healthcare organizations to provide additional data for assessment. Future application should emphasize obtaining improvements that lead to significant and sustainable value. Healthcare staff can use the results to target promising areas. This article comprehensively assesses Six Sigma healthcare applications and impact.

  18. Performance Evaluation of Photonic Sigma Delta ADCs

    DTIC Science & Technology

    2010-12-01

    65 APPENDIX B. MATLAB CODE FOR PHOTONIC SIGMA DELTA ADC.................67 APPENDIX C. SUBROUTINE FUNCTIONS...PHOTONIC SIGMA DELTA ADC FLOW CHART 66 THIS PAGE INTENTIONALLY LEFT BLANK 67 APPENDIX B. MATLAB CODE FOR PHOTONIC SIGMA DELTA ADC Program File...addition, a MATLAB simulation designed previously was used to simulate the behavior of the photonic sigma delta ADC. It was modified to speed up the

  19. Relationships between CMMI (trademark) and Six Sigma

    DTIC Science & Technology

    2005-12-01

    profitability is the central motive of Six Sigma. The quest to achieve the desired level of performance (as measured by sigma or another gauge) is based on...34* Lean 2 combined with Six Sigma is an increasingly occurring variant of the Six Sigma movement. The tactical aspects of Lean- Kaizen Events, in...particular-can be implemented within the existing DMAIC or DFSS frameworks. In a Kaizen Event, people examine the current state of a process or product and

  20. 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.

  1. 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.

  2. Branes in Poisson sigma models

    SciTech Connect

    Falceto, Fernando

    2010-07-28

    In this review we discuss possible boundary conditions (branes) for the Poisson sigma model. We show how to carry out the perturbative quantization in the presence of a general pre-Poisson brane and how this is related to the deformation quantization of Poisson structures. We conclude with an open problem: the perturbative quantization of the system when the boundary has several connected components and we use a different pre-Poisson brane in every component.

  3. Topological sigma models on supermanifolds

    NASA Astrophysics Data System (ADS)

    Jia, Bei

    2017-02-01

    This paper concerns constructing topological sigma models governing maps from semirigid super Riemann surfaces to general target supermanifolds. We define both the A model and B model in this general setup by defining suitable BRST operators and physical observables. Using supersymmetric localization, we express correlation functions in these theories as integrals over suitable supermanifolds. In the case of the A model, we obtain an integral over the supermoduli space of "superinstantons". The language of supergeometry is used extensively throughout this paper.

  4. 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.

  5. Strong hyperon-nucleon pairing in neutron stars.

    PubMed

    Zhou, Xian-Rong; Schulze, H-J; Pan, Feng; Draayer, J P

    2005-07-29

    We explore the possibilities of hyperon-nucleon pairing, involving lambda or sigma- hyperons, using different Nijmegen hyperon-nucleon potentials. We find possible very large nsigma- gaps and estimate their relevance for neutron star physics.

  6. Bacterial Sigma Factors and Anti-Sigma Factors: Structure, Function and Distribution.

    PubMed

    Paget, Mark S

    2015-06-26

    Sigma factors are multi-domain subunits of bacterial RNA polymerase (RNAP) that play critical roles in transcription initiation, including the recognition and opening of promoters as well as the initial steps in RNA synthesis. This review focuses on the structure and function of the major sigma-70 class that includes the housekeeping sigma factor (Group 1) that directs the bulk of transcription during active growth, and structurally-related alternative sigma factors (Groups 2-4) that control a wide variety of adaptive responses such as morphological development and the management of stress. A recurring theme in sigma factor control is their sequestration by anti-sigma factors that occlude their RNAP-binding determinants. Sigma factors are then released through a wide variety of mechanisms, often involving branched signal transduction pathways that allow the integration of distinct signals. Three major strategies for sigma release are discussed: regulated proteolysis, partner-switching, and direct sensing by the anti-sigma factor.

  7. The expression and functional characterization of sigma (sigma) 1 receptors in breast cancer cell lines.

    PubMed

    Aydar, Ebru; Onganer, Pinar; Perrett, Rebecca; Djamgoz, Mustafa B; Palmer, Christopher P

    2006-10-28

    Sigma (sigma) receptors have been implicated in cancer. However, to date there is little molecular data demonstrating the role of sigma1 receptors in cancer. Expression of sigma1 receptors in various human cancer cell lines in comparison to non-cancerous cell lines was investigated, using real time RT-PCR and by western blotting with a sigma1 receptor specific antibody. Our results indicate that cancer cells express higher levels of sigma1 receptors than corresponding non-cancerous cells. Localization of the sigma1 receptor was investigated in MDA-MB-231 cells by immunocytochemistry and confocal microscopy, expression was visualized predominantly at the cell periphery. We have tested the effect of sigma1 and sigma2 drugs and a sigma1 receptor silencing construct on various aspects of the metastatic process on two breast cell lines of different metastatic potential and a normal breast cell line. Both sigma1 and sigma2 drugs and the sigma1 receptor silencing construct had effects on proliferation and adhesion for breast cancer cell lines, compared to a non-cancerous breast cell line. This data suggests sigma1 receptor plays a role in proliferation and adhesion of breast cancer cells. Therefore, it is likely to be a potential target for the diagnosis and therapy of breast cancer.

  8. Imaging sigma receptors: applications in drug development.

    PubMed

    Collier, Thomas Lee; Waterhouse, Rikki N; Kassiou, Michael

    2007-01-01

    Sigma receptors have been implicated in a myriad of cellular functions, biological processes and diseases. While the precise biological functions of sigma receptors have not been elucidated, recent work has shed some light on to these enigmatic systems. Sigma receptors have recently been a target of drug development related to psychiatric and neurological disorders. Sigma ligands have also been shown to modulate endothelial cell proliferation and can control angiogenesis which makes them a promising target for oncology applications. Other areas currently being investigated include treatment of gastrointestinal, cardiovascular, endocrine and immune system disorders. Of interest is that the human sigma-1 receptor gene contains a steroid binding component, and several gonadal steroids, including progesterone, testosterone and dehydroepiandrosterone (DHEA), interact with sigma-1 receptors. Of the steroids examined thus far, progesterone binds with the highest affinity to human sigma-1 receptors, with a reported affinity (Ki) as high as 30 nM while the other steroids exhibit lower affinity. For this and other reasons, sigma-1 receptors have been proposed as a link between the central nervous system and the endocrine and reproductive systems. Taken together, the above information highlights an important yet largely unexplored but promising area of research to examine the biological function and therapeutic potential of sigma receptors. This review provides an overview of the current knowledge of these sites with a focus on specific areas where in vivo sigma receptor imaging is currently being investigated.

  9. 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.

  10. Resonances in the Sigma NN system

    NASA Astrophysics Data System (ADS)

    Gibson, B. F.; Afnan, I. R.

    We first review certain unique aspects of few-body Lambda-hypernuclei and then explore the physics of Sigma-hypernuclei that would produce structure near the Sigma threshold in few-body elastic scattering and reactions. In particular, we discuss a predicted enhancement in the lambda(d) cross section near the Sigma NN threshold in terms of poles in the Tau = 0 Y N N amplitude. A brief discussion of anticipated poles in the Tau = 1 amplitudes is also given.

  11. Separating Binary Stars and Supernova Remnants at Three Sigma

    NASA Astrophysics Data System (ADS)

    Dyer, K. K.

    2002-12-01

    High spatial resolution X-ray observations are revealing a population of point-like nonvariable sources in a host of nearby galaxies. These are normally identified as supernova remnants or X-ray binaries. However, in general these detections do not have enough counts to fully populate a spectrum, leaving identifications extremely speculative. I will present simulated spectra from models and data from well studied Galactic remnants and binary systems in order to demonstrate the uncertainty inherent in identifying sources with only few hundred counts. I will also explore the efficacy of using a hardness ratio to distinguish between source types and the role of optical and radio observations in clearing up ambiguities.

  12. Separating Binary Stars and Supernova Remnants at Three Sigma

    NASA Astrophysics Data System (ADS)

    Dyer, K. K.

    2003-03-01

    High spatial resolution X-ray observations are revealing a population of point-like nonvariable sources in a host of nearby galaxies. These are normally identified as supernova remnants or X-ray binaries. However, in general these detections do not have enough counts to fully populate a spectrum, leaving identifications extremely speculative. I will present simulated spectra from models and data from well studied Galactic remnants and binary systems in order to demonstrate the uncertainty inherent in identifying sources with only few hundred counts. I will also explore the efficacy of using a hardness ratio to distinguish between source types and the role of optical and radio observations in clearing up ambiguities.

  13. 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.

  14. Applying Sigma Metrics to Reduce Outliers.

    PubMed

    Litten, Joseph

    2017-03-01

    Sigma metrics can be used to predict assay quality, allowing easy comparison of instrument quality and predicting which tests will require minimal quality control (QC) rules to monitor the performance of the method. A Six Sigma QC program can result in fewer controls and fewer QC failures for methods with a sigma metric of 5 or better. The higher the number of methods with a sigma metric of 5 or better, the lower the costs for reagents, supplies, and control material required to monitor the performance of the methods. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. 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.

  16. TA-55 and Sigma Overview

    SciTech Connect

    Spearing, Dane Robert

    2016-11-29

    These are slides from a facility overview presentation for visiting agencies to Los Alamos National Laboratory (LANL). The TA-55 Plutonium Facility (PF-4) is discussed in detail. PF-4 is a unique resource for US plutonium programs. The basic design is flexible and has adapted to changing national needs. It is a robust facility with strong safety and security implementation. It supports a variety of national programs. It will continue for many years into the future. Sigma is then discussed in detail, which handles everything from hydrogen to uranium. It has been in long term service to the Nation (nearly 60 years). It has a flexible authorization basis to handle almost the entire periodic table. It has a wide breadth of prototyping and characterization capabilities. It has integrated program and line management.

  17. Sigma 2 Graphic Display Software Program Description

    NASA Technical Reports Server (NTRS)

    Johnson, B. T.

    1973-01-01

    A general purpose, user oriented graphic support package was implemented. A comprehensive description of the two software components comprising this package is given: Display Librarian and Display Controller. These programs have been implemented in FORTRAN on the XDS Sigma 2 Computer Facility. This facility consists of an XDS Sigma 2 general purpose computer coupled to a Computek Display Terminal.

  18. Lean Six Sigma implementation and organizational culture.

    PubMed

    Knapp, Susan

    2015-01-01

    The purpose of this paper is to examine the relationship between four organizational cultural types defined by the Competing Values Framework and three Lean Six Sigma implementation components - management involvement, use of Lean Six Sigma methods and Lean Six Sigma infrastructure. The study involved surveying 446 human resource and quality managers from 223 hospitals located in Maine, New Hampshire, Vermont, Massachusetts and Rhode Island using the Organizational Culture Assessment Instrument. Findings - In total, 104 completed responses were received and analyzed using multivariate analysis of variance. Follow-up analysis of variances showed management support was significant, F(3, 100)=4.89, p < 0.01, η2=1.28; infrastructure was not significant, F(3, 100)=1.55, p=0.21, η2=0.05; and using Lean Six Sigma methods was also not significant, F(3, 100)=1.34, p=0.26, η2=0.04. Post hoc analysis identified group and development cultures having significant interactions with management support. The relationship between organizational culture and Lean Six Sigma in hospitals provides information on how specific cultural characteristics impact the Lean Six Sigma initiative key components. This information assists hospital staff who are considering implementing quality initiatives by providing an understanding of what cultural values correspond to effective Lean Six Sigma implementation. Managers understanding the quality initiative cultural underpinnings, are attentive to the culture-shared values and norm's influence can utilize strategies to better implement Lean Six Sigma.

  19. 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

  20. 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.

  1. Correlation between neuroleptic binding to sigma(1) and sigma(2) receptors and acute dystonic reactions.

    PubMed

    Matsumoto, R R; Pouw, B

    2000-08-04

    Acute dystonic reactions are motor side effects that occur soon after the initiation of neuroleptic treatment. Although earlier studies indicate that these abnormal movements can be induced in animals and humans via activation of sigma receptors, the relative contribution of the different sigma receptor subtypes is unknown. Since sigma(1) and sigma(2) receptor are differentially represented in motor regions of the brain, the affinities of 17 neuroleptics for these sigma receptor subtypes were determined using competition binding studies. The results revealed that most neuroleptics do not exhibit selectivity for either of the sigma receptor subtypes, as reflected by a significant correlation between the affinities of the neuroleptics for sigma(1) vs. sigma(2) receptors. Moreover, when the sigma binding affinities of the neuroleptics were correlated with the tendency of the drugs to produce acute dystonic reactions in humans, there was a significant correlation for both subtypes. Together with earlier studies in animals, the data suggest that neuroleptic-induced motor side effects can be mediated through both sigma(1) and sigma(2) receptors.

  2. Sigma-1 Receptor in Motoneuron Disease.

    PubMed

    Mancuso, Renzo; Navarro, Xavier

    2017-01-01

    Amyotrophic Lateral Sclerosis (ALS ) is a neurodegenerative disease affecting spinal cord and brain motoneurons , leading to paralysis and early death. Multiple etiopathogenic mechanisms appear to contribute in the development of ALS , including glutamate excitotoxicity, oxidative stress , protein misfolding, mitochondrial defects, impaired axonal transport, inflammation and glial cell alterations. The Sigma-1 receptor is highly expressed in motoneurons of the spinal cord, particularly enriched in the endoplasmic reticulum (ER) at postsynaptic cisternae of cholinergic C-terminals. Several evidences point to participation of Sigma-1R alterations in motoneuron degeneration. Thus, mutations of the transmembrane domain of the Sigma-1R have been described in familial ALS cases. Interestingly, Sigma-1R KO mice display muscle weakness and motoneuron loss. On the other hand, Sigma-1R agonists promote neuroprotection and neurite elongation through activation of protein kinase C on motoneurons in vitro and in vivo after ventral root avulsion. Remarkably, treatment of SOD1 mice, the most usual animal model of ALS , with Sigma-1R agonists resulted in significantly enhanced motoneuron function and preservation, and increased animal survival. Sigma-1R activation also reduced microglial reactivity and increased the glial expression of neurotrophic factors. Two main interconnected mechanisms seem to underlie the effects of Sigma-1R manipulation on motoneurons: modulation of neuronal excitability and regulation of calcium homeostasis. In addition, Sigma-1R also contributes to regulating protein degradation, and reducing oxidative stress. Therefore, the multi-functional nature of the Sigma-1R represents an attractive target for treating aspects of ALS and other motoneuron diseases .

  3. {lambda}NN Three-Body Force due to Coherent {lambda}-{sigma} Coupling

    SciTech Connect

    Akaishi, Yoshinori; Myint, Khin Swe

    2008-04-29

    The overbinding problem of {sub {lambda}}{sup 5}He is solved by introducing a concept of coherent {lambda}-{sigma} coupling which is equivalent to a {lambda}NN three-body force. This three-body force is coherently enhanced in the 0{sup +} states of {sub {lambda}}{sup 4}H and {sub {lambda}}{sup 4}He. The 0{sup +}-1{sup +} splitting in these hypernuclei is mainly due to coherent {lambda}-{sigma} coupling and partly due to the {lambda}N spin-spin interaction. A {lambda}NN three-body potential is derived from the coupled-channel treatment. The origin of the repulsive and attractive nature of the three-body force is discussed. Coherent {lambda}-{sigma} coupling becomes more important in neutron-rich hypernuclei and especially in neutron-star matter at high densities. The possible existence of ''hyperheavy hydrogen'', {sub {lambda}}{sup 6}H, is suggested.

  4. Spin-forbidden c 3Sigma1+<--X 1Sigma+ band system of YF.

    PubMed

    Nagarajan, Ramya; Morse, Michael D

    2007-04-14

    Optical spectra of jet-cooled diatomic YF have been recorded using resonant two-photon ionization spectroscopy. A vibrational progression corresponding to the c 3Sigma1+<--X 1Sigma+ system has been identified. The vibrational frequency omegae' and anharmonicity omegae'xe' of the c 3Sigma+ state are 546.70 and 2.45 cm-1, respectively. The 0-0, 1-0, and 2-0 bands of the c 3Sigma1+<--X 1Sigma+ system were rotationally resolved and analyzed, allowing the v'=0, 1, and 2 levels of the c 3Sigma1+ substate to be characterized. From these studies, Be'=0.269 81(3) cm-1, alphae'=0.001 72(3) cm-1, and re'=1.9979(1) A were obtained (1sigma error limits). For these levels the spin-spin coupling constant lambdav is identical within experimental error, as lambda=-22.5 cm-1. The spin-forbidden c 3Sigma1+<--X 1Sigma+ transition is made allowed by spin-orbit interaction between the c 3Sigma1+ and the B 1Pi states. Excited state lifetimes of the c 3Sigma1+ and the B 1Pi states have been measured as 7.11(41) and 0.133(15) micros, respectively. A spin-orbit analysis shows that the c 3Sigma1+ state is contaminated with 2% B 1Pi character, which is approximately sufficient to explain the 7 micros lifetime of the c 3Sigma1+ state.

  5. 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.

  6. The biHermitian topological sigma model

    NASA Astrophysics Data System (ADS)

    Zucchini, Roberto

    2006-12-01

    BiHermitian geometry, discovered long ago by Gates, Hull and Rocek, is the most general sigma model target space geometry allowing for (2,2) world sheet supersymmetry. By using the twisting procedure proposed by Kapustin and Li, we work out the type A and B topological sigma models for a general biHermtian target space, we write down the explicit expression of the sigma model's action and BRST transformations and present a computation of the topological gauge fermion and the topological action.

  7. 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.}

  8. 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.

  9. Performance Test for the SIGMA Communication System

    NASA Astrophysics Data System (ADS)

    Jeong, Seonyeong; Lee, Hyojeong; Lee, Seongwhan; Shin, Jehyuck; Lee, Jungkyu; Jin, Ho

    2016-12-01

    Scientific CubeSat with Instruments for Global Magnetic Fields and Radiations (SIGMA) is a 3-U size CubeSat that will be operated in low earth orbit (LEO). The SIGMA communication system uses a very high frequency (VHF) band for uplink and an ultra high frequency (UHF) band for downlink. Both frequencies belong to an amateur band. The ground station that communicates with SIGMA is located at Kyung Hee Astronomical Observatory (KHAO). For reliable communication, we carried out a laboratory (LAB) test and far-field tests between the CubeSat and a ground station. In the field test, we considered test parameters such as attenuation, antenna deployment, CubeSat body attitude, and Doppler frequency shift in transmitting commands and receiving data. In this paper, we present a communication performance test of SIGMA, a link budget analysis, and a field test process. We also compare the link budget with the field test results of transmitting commands and receiving data.

  10. Closeup View - Sigma "7" Capsule - Recovery Ship

    NASA Image and Video Library

    1962-10-03

    S62-06175 (3 Oct. 1962) --- Closeup view of the Mercury-Atlas 8 (MA-8) Sigma 7 capsule being lowered to recovery ship's deck. Navy personnel remove the floatation device before opening the capsule. Photo credit: NASA

  11. Supersymmetric {sigma}-models in 2-dimensions

    SciTech Connect

    Zumino, B. |

    1997-02-01

    The author gives a brief introduction to supersymmetric {sigma}-models in two space-time dimensions. The topics he covers are: the bosonic {sigma}-model; supersymmetry in two dimensions; complex manifolds; the Kaehler and hyper-Kaehler case; and chiral supersymmetries. The lesson to be learned from the lecture is that the number of supersymmetries is intimately related to the geometric structure of the target space manifold: more geometric structure corresponds to more supersymmetries.

  12. 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.

  13. Bacterial Sigma Factors and Anti-Sigma Factors: Structure, Function and Distribution

    PubMed Central

    Paget, Mark S.

    2015-01-01

    Sigma factors are multi-domain subunits of bacterial RNA polymerase (RNAP) that play critical roles in transcription initiation, including the recognition and opening of promoters as well as the initial steps in RNA synthesis. This review focuses on the structure and function of the major sigma-70 class that includes the housekeeping sigma factor (Group 1) that directs the bulk of transcription during active growth, and structurally-related alternative sigma factors (Groups 2–4) that control a wide variety of adaptive responses such as morphological development and the management of stress. A recurring theme in sigma factor control is their sequestration by anti-sigma factors that occlude their RNAP-binding determinants. Sigma factors are then released through a wide variety of mechanisms, often involving branched signal transduction pathways that allow the integration of distinct signals. Three major strategies for sigma release are discussed: regulated proteolysis, partner-switching, and direct sensing by the anti-sigma factor. PMID:26131973

  14. Rudder-roll stabilization using fgs-pid controller for sigma-e warship

    NASA Astrophysics Data System (ADS)

    Santoso, M. Y.; Munadhif, I.; Wahidin, A.; Ruddianto; Fathulloh; Soelistijono, R. T.

    2017-06-01

    The aim of rudder-roll stabilization (RSS) is controlling ship heading and reducing roll motion simultaneously using one actuator, rudder. In this paper, RSS using FGS-PID for SIGMA-e warship was performed, both in normal and disturbed sea conditions. The fuzzy system for determining PID controller are constructed from SIGMA-e linear mathematical model. The wave disturbances are generated based on the WMO. The results show that FGS-PID has superior performance compared to conventional PID controller in heading control and roll damping. It means that the proposed control method can encounter the environmental changes.

  15. 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 +}

  16. Sigma meson in vacuum and nuclear matter

    NASA Astrophysics Data System (ADS)

    Menchaca-Maciel, M. C.; Morones-Ibarra, J. R.

    2013-04-01

    We have obtained the value of the interaction constant g σππ that adjusts the values obtained in the E791 Collaboration at Fermilab and BES Collaboration at the Beijing Electron Positron Collider experiments. To get this we have used the concept of critical width to make compatible the parameters obtained from the Breit-Wigner formula and those obtained from the density function. Also, the total width and effective mass modification of the sigma meson in nuclear matter has been studied in the Walecka model, assuming that the sigma couples to a pair of nucleon-antinucleon states and to particle-hole states, including the in-medium effect of sigma-omega mixing. We have considered, for completeness, the coupling of sigma to two virtual pions. We have found that the sigma meson mass decreases with respect to its value in vacuum and that the contribution of the sigma-omega mixing effect on the mass shift is relevant.

  17. 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.

  18. Regulation of antimicrobial resistance by extracytoplasmic function (ECF) sigma factors.

    PubMed

    Woods, Emily C; McBride, Shonna M

    2017-01-30

    Extracytoplasmic function (ECF) sigma factors are a subfamily of σ(70) sigma factors that activate genes involved in stress-response functions. In many bacteria, ECF sigma factors regulate resistance to antimicrobial compounds. This review will summarize the ECF sigma factors that regulate antimicrobial resistance in model organisms and clinically relevant pathogens.

  19. Identification and Analysis of Horizontal-Branch and Other A-Type Stars in the Galaxy

    NASA Astrophysics Data System (ADS)

    Rossi, Silvia C. F.; Beers, Timothy C.; Wilhelm, Ronald J.

    New techniques are being developed for the identification of Field Horizontal-Branch (FHB) and other A-type stars based on moderate-resolution spectroscopic observations and broadband UBV photometry. Physical parameters (T_eff, log g, and feh\\ ) for these stars can be estimated with accuracy on the order of sigma (T_eff) = 250 K, sigma (log g) = 0.35 dex, and sigma (feh ) = 0.30 dex, respectively. Detailed analysis such as this is required in order to form a ``clean'' sample of FHB stars, as such samples are easily confounded by the presence of halo blue stragglers (or BMP stars) and other high-gravity A-type stars. We summarize these analysis techniques, and discuss their application to a new large sample of FHB/A stars identified as part of the ongoing HK interference-filter/objective-prism survey of Beers and collaborators.

  20. The spectra of two new intermediate helium stars

    NASA Technical Reports Server (NTRS)

    Drilling, J. S.

    1981-01-01

    The stars designated as LSS 2394 and LS II + 36 deg 37 in the Case-Hamburg Luminous Stars surveys are found to be intermediate helium stars. The environment and spectrum of LSS 2394 (CPD -62 2124) appear to be quite similar to those of Sigma Ori E in a number of respects, including close proximity to two other OB stars, membership in a rich O association, spectrum variability, rapid rotation, and broad H-alpha emission wings. A low-resolution IUE spectrum for this star is presented and discussed.

  1. Bright Star Astrometry with URAT

    NASA Astrophysics Data System (ADS)

    Zacharias, N.

    2015-10-01

    The U.S. Naval Observatory Robotic Astrometric Telescope (URAT) is observing the northern sky since April 2012 for an astrometric survey. Multiple overlaps per year are performed in a single bandpass (680-750 nm) using the "redlens" 20 cm aperture astrograph and a mosaic of large CCDs. Besides the regular, deep survey to magnitude 18.5, short exposures with an objective grating are taken to access stars as bright as 3rd magnitude. A brief overview of the program, observing and reductions is given. Positions on the 8 to 20 mas level are obtained of 66,202 Hipparcos stars at current epochs. These are compared to the Hipparcos Catalog to investigate its accuracy. About 20% of the observed Hipparcos stars are found to have inconsistent positions with the Hipparcos Catalog prediction on the 3 sigma level or over (about 75 mas or more discrepant position offsets). Some stars are now seen at an arcsec (or 25 sigma) off their Hipparcos Catalog predicted position.

  2. Geometric sigma model of the Universe

    NASA Astrophysics Data System (ADS)

    Vasilić, Milovan

    2017-05-01

    The purpose of this work is to demonstrate how an arbitrarily chosen background of the Universe can be made a solution of a simple geometric sigma model. Geometric sigma models are purely geometric theories in which spacetime coordinates are seen as scalar fields coupled to gravity. Although they look like ordinary sigma models, they have the peculiarity that their complete matter content can be gauged away. The remaining geometric theory possesses a background solution that is predefined in the process of constructing the theory. The fact that background configuration is specified in advance is another peculiarity of geometric sigma models. In this paper, I construct geometric sigma models based on different background geometries of the Universe. Whatever background geometry is chosen, the dynamics of its small perturbations is shown to have a generic classical stability. This way, any freely chosen background metric is made a stable solution of a simple model. Three particular models of the Universe are considered as examples of how this is done in practice. Supported by Serbian Ministry of Education, Science and Technological Development (171031)

  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. Systematic Review of the Application of Lean and Six Sigma Quality Improvement Methodologies in Radiology.

    PubMed

    Amaratunga, Thelina; Dobranowski, Julian

    2016-09-01

    Preventable yet clinically significant rates of medical error remain systemic, while health care spending is at a historic high. Industry-based quality improvement (QI) methodologies show potential for utility in health care and radiology because they use an empirical approach to reduce variability and improve workflow. The aim of this review was to systematically assess the literature with regard to the use and efficacy of Lean and Six Sigma (the most popular of the industrial QI methodologies) within radiology. MEDLINE, the Allied & Complementary Medicine Database, Embase Classic + Embase, Health and Psychosocial Instruments, and the Ovid HealthStar database, alongside the Cochrane Library databases, were searched on June 2015. Empirical studies in peer-reviewed journals were included if they assessed the use of Lean, Six Sigma, or Lean Six Sigma with regard to their ability to improve a variety of quality metrics in a radiology-centered clinical setting. Of the 278 articles returned, 23 studies were suitable for inclusion. Of these, 10 assessed Six Sigma, 7 assessed Lean, and 6 assessed Lean Six Sigma. The diverse range of measured outcomes can be organized into 7 common aims: cost savings, reducing appointment wait time, reducing in-department wait time, increasing patient volume, reducing cycle time, reducing defects, and increasing staff and patient safety and satisfaction. All of the included studies demonstrated improvements across a variety of outcomes. However, there were high rates of systematic bias and imprecision as per the Grading of Recommendations Assessment, Development and Evaluation guidelines. Lean and Six Sigma QI methodologies have the potential to reduce error and costs and improve quality within radiology. However, there is a pressing need to conduct high-quality studies in order to realize the true potential of these QI methodologies in health care and radiology. Recommendations on how to improve the quality of the literature are proposed

  5. 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

  6. 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

  7. How the early sporulation sigma factor sigmaF delays the switch to late development in Bacillus subtilis.

    PubMed

    Karmazyn-Campelli, Céline; Rhayat, Lamya; Carballido-López, Rut; Duperrier, Sandra; Frandsen, Niels; Stragier, Patrick

    2008-03-01

    Sporulation in Bacillus subtilis is a primitive differentiation process involving two cell types, the forespore and the mother cell. Each cell implements two successive transcription programmes controlled by specific sigma factors. We report that activity of sigma(G), the late forespore sigma factor, is kept in check by Gin, the product of csfB, a gene controlled by sigma(F), the early forespore sigma factor. Gin abolishes sigma(G) transcriptional activity when sigma(G) is artificially synthesized during growth, but has no effect on sigma(F). Gin interacts strongly with sigma(G) but not with sigma(F) in a yeast two-hybrid experiment. The absence of Gin allows sigma(G) to be active during sporulation independently of the mother-cell development to which it is normally coupled. Premature sigma(G) activity leads to the formation of slow-germinating spores, and complete deregulation of sigma(G) synthesis is lethal when combined with gin inactivation. Gin allows sigma(F) to delay the switch to the late forespore transcription programme by preventing sigma(G) to take over before the cell has reached a critical stage of development. A similar strategy, following a completely unrelated route, is used by the mother cell.

  8. 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.

  9. 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.

  10. 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.

  11. Sigma Delta Dac Using Vhdl-Ams

    NASA Astrophysics Data System (ADS)

    Utage, S. A.; Dube, R. R.

    2010-11-01

    Sigma Delta Digital to analog converters (DACs) convert a binary number into a voltage directly proportional to the value of the binary number. A variety of applications use DACs including waveform generators and programmable voltage sources. This paper describes a Delta-Sigma DAC implemented in a FPGA. The only external circuitry required is a low pass filter comprised of just one resistor and one capacitor. Internal resource requirements are also minimal. The speed and flexible output structure of the FPGAs make them ideal for this application.

  12. 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.

  13. 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…

  14. 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…

  15. rpoE, the gene encoding the second heat-shock sigma factor, sigma E, in Escherichia coli.

    PubMed Central

    Rouvière, P E; De Las Peñas, A; Mecsas, J; Lu, C Z; Rudd, K E; Gross, C A

    1995-01-01

    In Escherichia coli, the heat shock response is under the control of two alternative sigma factors: sigma 32 and sigma E. The sigma 32-regulated response is well understood, whereas little is known about that of sigma E, except that it responds to extracytoplasmic immature outer membrane proteins. To further understand this response, we located the rpoE gene at 55.5' and analyzed the role of sigma E. sigma E is required at high temperature, and controls the transcription of at least 10 genes. Some of these might contribute to the integrity of the cell since delta rpoE cells are more sensitive to SDS plus EDTA and crystal violet. sigma E controls its own transcription from a sigma E-dependent promoter, indicating that rpoE transcription plays a role in the regulation of E sigma E activity. Indeed, under steady-state conditions, the transcription from this promoter mirrors the levels of E sigma E activity in the cell. However, it is unlikely that the rapid increase in E sigma E activity following induction can be accounted for solely by increased transcription of rpoE. Based upon homology arguments, we suggest that a gene encoding a negative regulator of sigma E activity is located immediately downstream of rpoE and may function as the target of the E sigma E inducing signal. Images PMID:7889934

  16. ELECTRON IMPACT DISSOCIATION X {sup 1}{Sigma}{sup +} {sub g} {yields} b {sup 3}{Sigma} {sub u} {sup +} AND EXCITATIONS X {sup 1}{Sigma}{sup +} {sub g} {yields} a {sup 3}{Sigma} {sub g} {sup +} AND X {sup 1}{Sigma}{sup +} {sub g} {yields} B {sup 1}{Sigma} {sub u} {sup +} OF MOLECULAR HYDROGEN IN NONTHERMAL ASTROPHYSICAL PLASMAS

    SciTech Connect

    Ki, Dae-Han; Jung, Young-Dae

    2013-02-15

    We investigate the electronic transitions X {sup 1}{Sigma}{sup +} {sub g} {yields} b {sup 3}{Sigma} {sub u} {sup +}, X {sup 1}{Sigma}{sup +} {sub g} {yields} a {sup 3}{Sigma} {sub g} {sup +}, and X {sup 1}{Sigma}{sup +} {sub g} {yields} B {sup 1}{Sigma} {sub u} {sup +} of molecular hydrogen by studying electron impacts in astrophysical Lorentzian plasmas. Useful fitting formulae for the X {sup 1}{Sigma}{sup +} {sub g} {yields} b {sup 3}{Sigma} {sub u} {sup +}, X {sup 1}{Sigma}{sup +} {sub g} {yields} a {sup 3}{Sigma} {sub g} {sup +}, and X {sup 1}{Sigma}{sup +} {sub g} {yields} B {sup 1}{Sigma} {sub u} {sup +} excitation cross sections are employed in order to obtain the electronic excitation rate coefficients of H{sub 2} as functions of the spectral index and temperature. In low-temperature regions, it is found that the excitation rate coefficients R{sub b{sup 3}{Sigma}{sub u{sup {sub +}}}}, R{sub a{sup 3}{Sigma}{sub g{sup {sub +}}}}, and R{sub B{sub {sup 1}{Sigma}{sub u{sup {sub +}}}}} of H{sub 2} in non-Maxwellian plasmas are smaller than those in Maxwellian plasmas. However, in high-temperature regions, the excitation rate coefficients of H{sub 2} in non-Maxwellian plasmas are greater than those in Maxwellian plasmas. It is also shown that the X {sup 1}{Sigma}{sup +} {sub g} {yields} b {sup 3}{Sigma} {sub u} {sup +} excitation rate coefficient is the main contributor in low-temperature regions. In contrast, it is found that the X {sup 1}{Sigma}{sup +} {sub g} {yields} B {sup 1}{Sigma} {sub u} {sup +} electronic excitation is dominant in high-temperature regions.

  17. 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…

  18. 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…

  19. 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…

  20. 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…

  1. 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…

  2. 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…

  3. 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.

  4. 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.

  5. Kac-Moody algebra and nonlinear sigma model

    NASA Astrophysics Data System (ADS)

    Ogura, Waichi; Hosoya, Akio

    1985-12-01

    We investigate the nonlinear sigma model over an arbitrary homogeneous space. Then it is shown that the sigma model realizes the Kac-Moody algebra as current algebra only if the homogeneous space is restricted to the group manifold.

  6. 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.

  7. Hyperfine structures of the 2 (3)Sigma(g) (+), 3 (3)Sigma(g) (+), and 4 (3)Sigma(g) (+) states of Na(2).

    PubMed

    Liu, Yaoming; Li, Li; Lazarov, Guenadiy; Lazoudis, Angelos; Lyyra, A Marjatta; Field, Robert W

    2004-09-22

    The hyperfine structures of the 2 (3)Sigma(g) (+), 3 (3)Sigma(g) (+), and 4 (3)Sigma(g) (+) states of Na(2) have been resolved with sub-Doppler continuous wave perturbation facilitated optical-optical double resonance spectroscopy via A (1)Sigma(u) (+) approximately b (3)Pi(u) mixed intermediate levels. The hyperfine patterns of these three states are similar. The hyperfine splittings of the low rotational levels are all very close to the case b(betaS) limit. As the rotational quantum number increases, the hyperfine splittings become more complicated and the coupling cases become intermediate between cases b(betaS) and b(beta J) due to spin-rotation interaction. We present a detailed analysis of the hyperfine structures of these three (3)Sigma(g) (+) states, employing both case b(betaS) and b(beta J) coupling basis sets. The results show that the hyperfine splittings of the (3)Sigma(g) (+) states are mainly due to the Fermi-contact interaction. The Fermi contact constants for the two d sigma Rydberg states, the 2 (3)Sigma(g) (+) and 4 (3)Sigma(g) (+), are 245+/-5 MHz and 225+/-5 MHz, respectively, while the Fermi contact constant of the s sigma 3 (3)Sigma(g) (+) Rydberg state is 210+/-5 MHz. The diagonal spin-spin and spin-rotation constants, and nuclear spin-electronic spin dipolar interaction parameters of the 3 (3)Sigma(g) (+) and 4 (3)Sigma(g) (+) states are also obtained.

  8. 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…

  9. 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…

  10. 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.

  11. 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.

  12. EXTENDED SCHMIDT LAW: ROLE OF EXISTING STARS IN CURRENT STAR FORMATION

    SciTech Connect

    Shi Yong; Helou, George; Yan Lin; Armus, Lee; Wu Yanling; Stierwalt, Sabrina; Papovich, Casey

    2011-06-01

    We propose an 'extended Schmidt law' with explicit dependence of the star formation efficiency (SFE = SFR/M{sub gas}) on the stellar mass surface density ({Sigma}{sub star}). This relation has a power-law index of 0.48 {+-} 0.04 and a 1{sigma} observed scatter on the SFE of 0.4 dex, which holds over five orders of magnitude in the stellar density for individual global galaxies, including various types and especially the low-surface-brightness (LSB) galaxies that deviate significantly from the Kennicutt-Schmidt (KS) law. When applying it to regions of a sample of 12 spiral galaxies at sub-kiloparsec resolution, the extended Schmidt law not only holds for LSB regions but also shows significantly smaller scatters both within and across galaxies compared with the KS law. We argue that this new relation points to the role of existing stars in regulating the SFE, thus better encoding the star formation physics. Comparison with physical models of star formation recipes shows that the extended Schmidt law can be reproduced by some models including gas free fall in a stellar-gravitational potential and pressure-supported star formation. By implementing this new law into the analytic model of gas accretion in {Lambda}CDM, we show that it can reproduce the observed main sequence of star-forming galaxies (a relation between the SFR and stellar mass) from z = 0 up to z = 2.

  13. Narrow structure in {Lambda}d scattering near the {Sigma} threshold ({sub {Sigma}}{sup 3}He states)

    SciTech Connect

    Gibson, B.F.; Afnan, I.R.

    1991-12-31

    A separable-potential, Faddeev-type calculation of {Lambda}-deuteron scattering near the threshold for {Sigma} production is shown to produce structure (a resonance peak) in the cross section which lies below the {Sigma} threshold for two different YN ({Lambda}N-{Sigma}N coupled-channel) potential models. In one case the {Sigma}NN eigenvalue corresponds to a pole which lies below threshold (bound) and in the second case the poles lies above the threshold.

  14. Pharmacology and therapeutic potential of sigma(1) receptor ligands.

    PubMed

    Cobos, E J; Entrena, J M; Nieto, F R; Cendán, C M; Del Pozo, E

    2008-12-01

    Sigma (sigma) receptors, initially described as a subtype of opioid receptors, are now considered unique receptors. Pharmacological studies have distinguished two types of sigma receptors, termed sigma(1) and sigma(2). Of these two subtypes, the sigma(1) receptor has been cloned in humans and rodents, and its amino acid sequence shows no homology with other mammalian proteins. Several psychoactive drugs show high to moderate affinity for sigma(1) receptors, including the antipsychotic haloperidol, the antidepressant drugs fluvoxamine and sertraline, and the psychostimulants cocaine and methamphetamine; in addition, the anticonvulsant drug phenytoin allosterically modulates sigma(1) receptors. Certain neurosteroids are known to interact with sigma(1) receptors, and have been proposed to be their endogenous ligands. These receptors are located in the plasma membrane and in subcellular membranes, particularly in the endoplasmic reticulum, where they play a modulatory role in intracellular Ca(2+) signaling. Sigma(1) receptors also play a modulatory role in the activity of some ion channels and in several neurotransmitter systems, mainly in glutamatergic neurotransmission. In accordance with their widespread modulatory role, sigma(1) receptor ligands have been proposed to be useful in several therapeutic fields such as amnesic and cognitive deficits, depression and anxiety, schizophrenia, analgesia, and against some effects of drugs of abuse (such as cocaine and methamphetamine). In this review we provide an overview of the present knowledge of sigma(1) receptors, focussing on sigma(1) ligand neuropharmacology and the role of sigma(1) receptors in behavioral animal studies, which have contributed greatly to the potential therapeutic applications of sigma(1) ligands.

  15. Nonuniversal star formation efficiency in turbulent ISM

    SciTech Connect

    Semenov, Vadim A.; Kravtsov, Andrey V.; Gnedin, Nickolay Y.

    2016-07-29

    Here, we present a study of a star formation prescription in which star formation efficiency depends on local gas density and turbulent velocity dispersion, as suggested by direct simulations of SF in turbulent giant molecular clouds (GMCs). We test the model using a simulation of an isolated Milky Way-sized galaxy with a self-consistent treatment of turbulence on unresolved scales. We show that this prescription predicts a wide variation of local star formation efficiency per free-fall time, $\\epsilon_{\\rm ff} \\sim 0.1 - 10\\%$, and gas depletion time, $t_{\\rm dep} \\sim 0.1 - 10$ Gyr. In addition, it predicts an effective density threshold for star formation due to suppression of $\\epsilon_{\\rm ff}$ in warm diffuse gas stabilized by thermal pressure. We show that the model predicts star formation rates in agreement with observations from the scales of individual star-forming regions to the kiloparsec scales. This agreement is non-trivial, as the model was not tuned in any way and the predicted star formation rates on all scales are determined by the distribution of the GMC-scale densities and turbulent velocities $\\sigma$ in the cold gas within the galaxy, which is shaped by galactic dynamics. The broad agreement of the star formation prescription calibrated in the GMC-scale simulations with observations, both gives credence to such simulations and promises to put star formation modeling in galaxy formation simulations on a much firmer theoretical footing.

  16. Nonuniversal star formation efficiency in turbulent ISM

    SciTech Connect

    Semenov, Vadim A.; Kravtsov, Andrey V.; Gnedin, Nickolay Y.

    2016-07-29

    Here, we present a study of a star formation prescription in which star formation efficiency depends on local gas density and turbulent velocity dispersion, as suggested by direct simulations of SF in turbulent giant molecular clouds (GMCs). We test the model using a simulation of an isolated Milky Way-sized galaxy with a self-consistent treatment of turbulence on unresolved scales. We show that this prescription predicts a wide variation of local star formation efficiency per free-fall time, $\\epsilon_{\\rm ff} \\sim 0.1 - 10\\%$, and gas depletion time, $t_{\\rm dep} \\sim 0.1 - 10$ Gyr. In addition, it predicts an effective density threshold for star formation due to suppression of $\\epsilon_{\\rm ff}$ in warm diffuse gas stabilized by thermal pressure. We show that the model predicts star formation rates in agreement with observations from the scales of individual star-forming regions to the kiloparsec scales. This agreement is non-trivial, as the model was not tuned in any way and the predicted star formation rates on all scales are determined by the distribution of the GMC-scale densities and turbulent velocities $\\sigma$ in the cold gas within the galaxy, which is shaped by galactic dynamics. The broad agreement of the star formation prescription calibrated in the GMC-scale simulations with observations, both gives credence to such simulations and promises to put star formation modeling in galaxy formation simulations on a much firmer theoretical footing.

  17. CH Stars and Barium Stars

    NASA Astrophysics Data System (ADS)

    Bond, H.; Sion, E.; Murdin, P.

    2000-11-01

    The classical barium (or `Ba II') stars are RED GIANT STARS whose spectra show strong absorption lines of barium, strontium and certain other heavy elements, as well as strong features due to carbon molecules. Together with the related class of CH stars, the Ba II stars were crucial in establishing the existence of neutron-capture reactions in stellar interiors that are responsible for the synt...

  18. 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.

  19. Sigma-1 receptors are essential for capsaicin-induced mechanical hypersensitivity: studies with selective sigma-1 ligands and sigma-1 knockout mice.

    PubMed

    Entrena, José Manuel; Cobos, Enrique José; Nieto, Francisco Rafael; Cendán, Cruz Miguel; Gris, Georgia; Del Pozo, Esperanza; Zamanillo, Daniel; Baeyens, José Manuel

    2009-06-01

    We evaluated the role of sigma(1) receptors on capsaicin-induced mechanical hypersensitivity and on nociceptive pain induced by punctate mechanical stimuli, using wild-type and sigma(1) receptor knockout (sigma(1)-KO) mice and selective sigma(1) receptor-acting drugs. Mutation in sigma(1)-KO mice was confirmed by PCR analysis of genomic DNA and, at the protein level, by [(3)H](+)-pentazocine binding assays. Both wild-type and sigma(1)-KO mice not treated with capsaicin showed similar responses to different intensities of mechanical stimuli (0.05-8 g force), ranging from innocuous to noxious, applied to the hind paw. This indicates that sigma(1) gene inactivation does not modify the perception of punctate mechanical stimuli. The intraplantar (i.pl.) administration of capsaicin induced dose-dependent mechanical allodynia in wild-type mice (markedly reducing both the threshold force necessary to induce paw withdrawal and the latency to paw withdrawal induced by a given force). In contrast, capsaicin was completely unable to induce mechanical hypersensitivity in sigma(1)-KO mice. The high-affinity and selective sigma(1) antagonists BD-1063, BD-1047 and NE-100, administered subcutaneously (s.c.), dose-dependently inhibited mechanical allodynia induced by capsaicin (1 microg,i.pl.), yielding ED(50) (mg/kg) values of 15.80+/-0.93, 29.31+/-1.65 and 40.74+/-7.20, respectively. The effects of the sigma(1) antagonists were reversed by the sigma(1) agonist PRE-084 (32 mg/kg, s.c.). None of the drugs tested modified the responses induced by a painful mechanical punctate stimulus (4 g force) in nonsensitized animals. These results suggest that sigma(1) receptors are essential for capsaicin-induced mechanical hypersensitivity, but are not involved in mechanical nociceptive pain.

  20. The Rhodobacter sphaeroides ECF sigma factor, sigma(E), and the target promoters cycA P3 and rpoE P1.

    PubMed

    Newman, J D; Falkowski, M J; Schilke, B A; Anthony, L C; Donohue, T J

    1999-11-26

    Rhodobacter sphaeroides rpoE encodes a 19.2 kDa protein, sigma(E), related to members of the extra-cytoplasmic function subfamily of eubacterial RNA polymerase sigma factors. We demonstrate that sigma(E) directs transcription from rpoE P1, the promoter for the rpoEchrR operon, and from cycA P3, a promoter for the cytochrome c2 structural gene. Comparison of these sigma(E)-dependent promoters reveals significant sequence conservation in their -35 and -10 regions; however, rpoE P1 is over 80-fold stronger than cycA P3. Both promoters contain identical -35 hexamers, (-36)TGATCC(-31), that appear to constitute the preferred sequence, since any single base mutation in this region of cycA P3 reduces promoter function. The higher activity of rpoE P1 appears to reflect a better -10 region, (-13)TAAGA(-9), as it contains four out of five of the nucleotides found to be important to sigma(E)-dependent transcription. We also propose that ChrR acts as an inhibitor of sigma(E), since these two proteins can form a complex, and DeltachrR mutations increase sigma(E)-dependent transcription. ChrR is believed to respond to a signal from tetrapyrrole biosynthesis because loss of function mutations in chrR lead to cohemin resistance. Based on our observations, we present a model in which cohemin resistance is conferred by increasing sigma(E) activity. Copyright 1999 Academic Press.

  1. Sigma-Model Solitons on Noncommutative Spaces

    NASA Astrophysics Data System (ADS)

    Dabrowski, Ludwik; Landi, Giovanni; Luef, Franz

    2015-12-01

    We use results from time-frequency analysis and Gabor analysis to construct new classes of sigma-model solitons over the Moyal plane and over noncommutative tori, taken as source spaces, with a target space made of two points. A natural action functional leads to self-duality equations for projections in the source algebra. Solutions, having nontrivial topological content, are constructed via suitable Morita duality bimodules.

  2. 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.

  3. 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).

  4. Shifts from glucose to certain secondary carbon-sources result in activation of the extracytoplasmic function sigma factor sigmaE in Salmonella enterica serovar Typhimurium.

    PubMed

    Kenyon, William J; Thomas, Sheena M; Johnson, Erin; Pallen, Mark J; Spector, Michael P

    2005-07-01

    Salmonella enterica serovar Typhimurium (S. Typhimurium) elicits the starvation-stress response (SSR) due to starvation for an essential nutrient, e.g. a carbon/energy source (C-source). As part of the SSR, the alternative sigma factor sigma(E) is activated and induced. The authors suspect that this activation is, in part, triggered by changes in the S. Typhimurium cell envelope occurring during the adaptation from growth to carbon/energy starvation (C-starvation), and resulting in an increased need for sigma(E)-regulated factors involved in the proper folding and assembly of newly synthesized proteins destined for this extracytoplasmic compartment. This led to the hypothesis that a sigma(E) activation signal might arise during C-source shifts that cause the induction of proteins localized to the extracytoplasmic compartment, i.e. the outer membrane or periplasm, of the cell. To test this hypothesis, cultures were grown in minimal medium containing enough glucose to reach mid-exponential-phase, plus a non-limiting amount of a secondary 'less-preferred' but utilizable carbon/energy source. The sigma(E) activity was then monitored using plasmids carrying rpoEP1- and rpoEP2-lacZ transcriptional fusions, which exhibit sigma(E)-independent and -dependent lacZ expression, respectively. The secondary C-sources maltose, succinate and citrate, which have extracytoplasmic components involved in their utilization (e.g. LamB), resulted in a discernible diauxic lag period and a sustained increase in sigma(E) activity. Growth transition from glucose to other utilizable phosphotransferase (PTS) and non-PTS C-sources, such as trehalose, mannose, mannitol, fructose, glycerol, d-galactose or l-arabinose, did not cause a discernible diauxic lag period or a sustained increase in sigma(E) activity. Interestingly, a shift from glucose to melibiose, which does not use an extracytoplasmic-localized protein for uptake, did cause an observable diauxic lag period but did not result in a

  5. Mucosal vaccination by adenoviruses displaying reovirus sigma 1.

    PubMed

    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

    2015-08-01

    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.

  6. A comparison of simulated precipitation by hybrid isentropic-sigma and sigma models

    NASA Technical Reports Server (NTRS)

    Johnson, Donald R.; Zapotocny, Tom H.; Reames, Fred M.; Wolf, Bart J.; Pierce, R. B.

    1993-01-01

    Simulations of dry and moist baroclinic development from 10- and 22-layer hybrid isentropic-sigma coordinate models are compared with those from 11-, 27-, and 35-layer sigma coordinate models. The ability of the models to transport water vapor and simulate equivalent potential temperature is examined. Predictions of the timing, location, and amount of precipitation are compared. Several analytical distributions of water vapor are specified initially. It is shown that when the relative humidity is vertically uniform through a substantial extent of the atmosphere, all the models produce very similar precipitation distributions. However, when water vapor is confined to relatively shallow layers, the ability of the sigma coordinate models to simulate the timing, location, and amount of precipitation is severely compromised.

  7. 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.

  8. 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.

  9. The APOGEE view of Be stars

    NASA Astrophysics Data System (ADS)

    Eikenberry, Stephen S.; Chojnowski, S.; Wisniewski, J. P.; Majewski, S. R.; Shetrone, M. D.; Whelan, D. G.; Bizyaev, D.; Borish, H.; Davenport, J. R.; Ebelke, G.; Feuillet, D.; Garner, A.; Hearty, F.; Holtzman, J. A.; Li, Z.; Meczaros, S.; Nidever, D. L.; Schneider, D. P.; Skrutskie, M. F.; Wilson, J. C.; Zasowski, G.

    2014-01-01

    I will present an overview of the 100+ previously unidentified Be stars discovered during the APOGEE survey. I will particularly focus on the new highly-magnetized Rigidly Rotating Magnetosphere (RRM) stars of the Sigma Orionis E type we have found. Both of the discovered stars show the spectroscopic signatures of the rigidly rotating magnetospheres common to this class of highly-magnetized (B ˜10 kiloGauss) stars. One (ABES-050) is an early main-sequence B star with unusually strong He absorption (similar to Sig Ori E), while the other (ABES-075) appears to be “He-normal” with a B3 IV subtype - the first known magnetized RRM star that is He-normal and possibly off the main sequence. We combine the APOGEE discovery spectra with other optical and near-infrared spectra of these two stars, as well as of Sig Ori E itself, to show how near-infrared spectroscopy can be a powerful tool for discovering more of these rare objects. We discuss the potential for further discovery of Sig Ori E type stars, as well as the implications of our discoveries for the population of these objects and insights into their origin and evolution.

  10. 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.

  11. Neutron Stars

    NASA Technical Reports Server (NTRS)

    Cottam, J.

    2007-01-01

    Neutron stars were discovered almost 40 years ago, and yet many of their most fundamental properties remain mysteries. There have been many attempts to measure the mass and radius of a neutron star and thereby constrain the equation of state of the dense nuclear matter at their cores. These have been complicated by unknown parameters such as the source distance and burning fractions. A clean, straightforward way to access the neutron star parameters is with high-resolution spectroscopy. I will present the results of searches for gravitationally red-shifted absorption lines from the neutron star atmosphere using XMM-Newton and Chandra.

  12. Euclidean supersymmetry, twisting and topological sigma models

    NASA Astrophysics Data System (ADS)

    Hull, C. M.; Lindström, U.; Melo dos Santos, L.; von Unge, R.; Zabzine, M.

    2008-06-01

    We discuss two dimensional N-extended supersymmetry in Euclidean signature and its R-symmetry. For N = 2, the R-symmetry is SO(2) × SO(1, 1), so that only an A-twist is possible. To formulate a B-twist, or to construct Euclidean N = 2 models with H-flux so that the target geometry is generalised Kahler, it is necessary to work with a complexification of the sigma models. These issues are related to the obstructions to the existence of non-trivial twisted chiral superfields in Euclidean superspace.

  13. 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]).

  14. Lambda and Sigma photoproduction on the neutron

    SciTech Connect

    P. Nadel-Turonski; B. L. Berman

    2006-06-01

    The gamma n --> K^0_s Y and gamma n --> K^+Sigma^-(1385) channels are being analyzed using the CLAS g10 data set. As recent calculations show a large sensitivity of, e.g., the proposed D_13(1900) resonance to polarization observables, we hope to extend this study by making a new experiment with polarized real photon beams and an LD_2 target in CLAS, to measure all gamma(pol) n --> K(pol)Y reactions. N* decays to low-lying KY* and K*Y states, as well as Y(pol)-N final state interactions would also be investigated.

  15. Lean Six Sigma Challenges and Opportunities

    DTIC Science & Technology

    2008-02-13

    St ra te gy R es ea rc h Pr oj ec t LEAN SIX SIGMA CHALLENGES AND OPPORTUNITIES BY COLONEL LINDA R. HERBERT United States Army ...not reflect the official policy or position of the Department of the Army , Department of Defense, or the U.S. Government. U.S. Army War College...5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) U.S. Army War College ,122 Forbes Ave

  16. String Field Equations from Generalized Sigma Model

    SciTech Connect

    Bardakci, K.; Bernardo, L.M.

    1997-01-29

    We propose 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. We apply it to the tachyon, massless and first massive level, and show that the resulting field equations reproduce the correct spectrum of a left-right symmetric closed bosonic string.

  17. Properties of the sigma meson at finite temperature

    NASA Astrophysics Data System (ADS)

    Ibarra, J. R. Morones; Aguirre, A. J. Garza; Flores-Baez, Francisco V.

    2015-12-01

    We study the changes of the mass and width of the sigma meson in the framework of the Linear Sigma Model at finite temperature, in the one-loop approximation. We have found that as the temperature increases, the mass of sigma shifts down. We have also analyzed the σ-spectral function and we observe an enhancement at the threshold which is a signature of partial restoration of chiral symmetry, also interpreted as a tendency to chiral phase transition. Additionally, we studied the width of the sigma, when the threshold enhancement takes place, for different values of the sigma mass. We found that there is a brief enlargement followed by an abrupt fall in the width as the temperature increases, which is also related with the restoration of chiral symmetry and an indication that the sigma is a bound state of two pions.

  18. The Polarization and Magnetic Moment of the $\\Sigma^- Hyperon$

    SciTech Connect

    Deck, Leslie Ludwig

    1982-11-01

    The magnitude of the polarization of 516,229 inclusively produced $\\Sigma^-$'s has been measured to be 15.5±3.6%. The $\\Sigma^-$'s were produced by 400 GeV/c protons on Be at angles of $\\pm$7.5 mr with respect to the incident proton direction and had momenta between 120 and 290 GeV/c, with a mean momentum of 176 GeV/c. The polarization was measured from the asymmetry in the decay $\\Sigma^- \\eta + \\pi^-$ The $\\Sigma^-$ magnetic moment was also determined to be -0.89 $\\pm$ 0.l4 $\\mu_N$ corresponding to an anomalous precession angle of 11$^{\\circ}$+15°.

  19. g{sub {Sigma}{sub Q{Sigma}{sub Q{pi}}}}coupling constant via light cone QCD sum rules

    SciTech Connect

    Azizi, K.; Bayar, M.; Ozpineci, A.; Sarac, Y.

    2010-10-01

    Using the most general form of the interpolating currents, the coupling constants g{sub {Sigma}{sub b{Sigma}{sub b{pi}}}}and g{sub {Sigma}{sub c{Sigma}{sub c{pi}}}}are calculated within the light cone QCD sum rules approach. It is found that g{sub {Sigma}{sub c{Sigma}{sub c{pi}=}}}-8.0{+-}1.7 and g{sub {Sigma}{sub b{Sigma}{sub b{pi}=}}}-11.0{+-}2.1.

  20. 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.

  1. Radio stars

    NASA Astrophysics Data System (ADS)

    Hjellming, Robert M.

    The state of knowledge on continuum radio emission from the stars is considered. Fundamental radio emission process and stellar radiative transfer are reviewed, and solar radio emission is examined. Flare stars and active binaries are addressed, and stellar winds and cataclysmic variables are considered. Radio-emitting X-ray binaries are discussed.

  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. Star formation in massive Milky Way molecular clouds: Building a bridge to distant galaxies

    NASA Astrophysics Data System (ADS)

    Willis, Sarah Elizabeth

    The Kennicutt-Schmidt relation is an empirical power-law linking the surface density of the star formation rate (SigmaSFR) to the surface density of gas (Sigmagas ) averaged over the observed face of a starforming galaxy Kennicutt (1998). The original presentation used observations of CO to measure gas density and H alpha emission to measure the population of hot, massive young stars (and infer the star formation rate). Observations of Sigma SFR from a census of young stellar objects in nearby molecular clouds in our Galaxy are up to 17 times higher than the extragalactic relation would predict given their Sigmagas. These clouds primarily form low-mass stars that are essentially invisible to star formation rate tracers. A sample of six giant molecular cloud (GMC) complexes with signposts of massive star formation was identified in our galaxy. The regions selected have a range of total luminosity and morphology. Deep ground-based observations in the near-infrared with NEWFIRM and IRAC observations with the Spitzer Space Telescope were used to conduct a census of the young stellar content associated with each of these clouds. The star formation rates from the stellar census in each of these regions was compared with the star formation rates measured by extragalactic star formation rate tracers based on monochromatic mid-infrared luminosities. Far-infrared Herschel observations from 160 through 500 mum were used to determine the column density and temperature in each region. The region NGC 6334 served as a test case to compare the Herschel column density measurements with the measurements for near-infrared extinction. The combination of the column density maps and the stellar census lets us examine SigmaSFR vs. Sigma gas for the massive GMCs. These regions are consistent with the results for the low-mass molecular clouds, indicating Sigma SFR levels that are higher than predicted based on Sigma gas. The overall Sigmagas levels are higher for the massive star forming

  4. Superconducting bandpass delta-sigma modulator

    NASA Astrophysics Data System (ADS)

    Bulzacchelli, J. F.; Lee, H.-S.; Misewich, J. A.; Ketchen, M. B.

    1999-11-01

    Bandpass delta-sigma modulators digitize narrowband signals with high dynamic range and linearity. The required sampling rate is only a few times higher than the centre frequency of the input. This paper presents a superconducting bandpass delta-sigma modulator for direct analogue-to-digital conversion of RF signals in the GHz range. The input signal is capacitively coupled to one end of a microstrip transmission line, and a single flux quantum balanced comparator quantizes the current flowing out of the other end. Quantization noise is suppressed at the quarter-wave resonance of the transmission line (about 2 GHz in our design). Circuit performance at a 20 GHz sampling rate has been studied with several long JSIM simulations. Full-scale (FS) input sensitivity is 20 mV (rms), and in-band noise is -53 dBFS and -57 dBFS over bandwidths of 39 MHz and 19.5 MHz, respectively. In-band intermodulation distortion is better than -69 dBFS.

  5. 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.

  6. Sigma-1 receptors modulate functional activity of rat splenocytes.

    PubMed

    Liu, Y; Whitlock, B B; Pultz, J A; Wolfe, S A

    1995-06-01

    Neuroleptics, opiates, and cocaine are commonly prescribed for or abused by humans. Although primarily used for their actions at other receptors in brain, these compounds also act at sigma receptors. We have previously identified sigma-1 receptors on human peripheral blood leukocytes and rat spleen, and in the present study we demonstrate a correlation between the pharmacology of these receptors and the ability of drugs to suppress concanavalin A-induced splenocyte proliferation. These results support the hypothesis that sigma-1 receptors regulate functional activities of immune cells, and suggest that sigma agonists may cause changes in immune competence in vivo.

  7. Ultraviolet spectrophotometry from Gemini 11 of stars in Orion

    NASA Technical Reports Server (NTRS)

    Morgan, T. H.; Spear, G. G.; Kondo, Y.; Henize, K. G.

    1975-01-01

    Ultraviolet spectrophotometry in the wavelength region 2600-3600 A is reported for the bright early-type stars beta, eta, gamma, delta, iota, epsilon, sigma, zeta, and kappa Ori. The results are in good agreement with other observations, and, with the possible exception of the supergiants, are in good agreement with recent line-blanketed model atmospheres. There is evidence that the supergiants possess a small ultraviolet deficiency shortward of 3000 A relative to main-sequence stars of similar spectral type. The most extreme example of this phenomenon is the star kappa Ori.

  8. Ultraviolet spectrophotometry from Gemini 11 of stars in Orion

    NASA Technical Reports Server (NTRS)

    Morgan, T. H.; Spear, G. G.; Kondo, Y.; Henize, K. G.

    1975-01-01

    Ultraviolet spectrophotometry in the wavelength region 2600-3600 A is reported for the bright early-type stars beta, eta, gamma, delta, iota, epsilon, sigma, zeta, and kappa Ori. The results are in good agreement with other observations, and, with the possible exception of the supergiants, are in good agreement with recent line-blanketed model atmospheres. There is evidence that the supergiants possess a small ultraviolet deficiency shortward of 3000 A relative to main-sequence stars of similar spectral type. The most extreme example of this phenomenon is the star kappa Ori.

  9. 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.

  10. 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.

  11. Generation of O2/c 1Sigma u -, C 3Delta u, A 3Sigma u +/ from oxygen atom recombination

    NASA Technical Reports Server (NTRS)

    Slanger, T. G.

    1978-01-01

    The spectrum produced in the afterglow of an O2-He discharge was studied for the range 4000-8000 A. Lawrence et al. (1977) established that under the appropriate conditions the O2(c 1Sigma u - to X 3Sigma g -) system could be observed in this region. The present study has duplicated these results and has discovered three O2 band systems not previously seen in gas phase laboratory spectra. These systems are C 3Delta u-a 1Delta g, C 3Delta u-X 3Sigma g -, and c 1Sigma u - to a 1Delta g.

  12. Spectrophotometry of 237 Stars in 7 Open Clusters

    NASA Astrophysics Data System (ADS)

    Clampitt, Lori; Burstein, David

    1997-08-01

    Spectrophotometry is presented for 237 stars in 7 nearby open clusters: Hyades, Pleiades, Alpha Persei, Praesepe, Coma Berenices, IC 4665, and M39. The observations were taken by Lee McDonald and David Burstein using the Wampler single-channel scanner on the Crossley 0.9m telescope at Lick Observatory from July 1973 through December 1974. Sixteen bandpasses spanning the spectral range 3500 Angstroms to 7780 Angstroms were observed for each star, with bandwidths 32Angstroms, 48 Angstroms or 64 Angstroms. Data are standardized to the Hayes-Latham system to mutual accuracy of 0.016 mag per passband. The accuracy of the spectrophotometry is assessed in three ways on a star-by-star basis. First, comparisons are made with previously published spectrophotometry for 19 stars observed in common. Second, (B-V) colors and uvby colors are compared for 236 stars and 221 stars, respectively. Finally, comparsions are made for 200 main sequence stars to the spectral synthesis models of Kurucz, fixing log g = 4.0 and [Fe/H] = 0.0, and only varying effective temperature. The accuracy of tests using uvby colors and the Kurucz models are shown to track each other closely, yielding an accuracy estimate (1 sigma ) of 0.01 mag for the 13 colors formed from bandpasses longward of the Balmer jump, and 0.02 mag for the 3 colors formed from the three bandpasses below the Balmer jump. In contrast, larger scatter is found relative to the previously published spectrophotometry of Bohm-Vitense & Johnson (16 stars in common) and Gunn & Stryker (3 stars). We also show that the scatter in the fits of the spectrophotometric colors and the uvby filter colors is a reasonable way to identify the observations of which specific stars are accurate to 1 sigma , 2 sigma , .... As such, the residuals from both the filter color fits and the Kurucz model fits are tabulated for each star where it was possible to make a comparison, so users of these data can choose stars according to the accuracy of the data

  13. Quantitative application of sigma metrics in medical biochemistry.

    PubMed

    Nanda, Sunil Kumar; Ray, Lopamudra

    2013-12-01

    Laboratory errors are result of a poorly designed quality system in the laboratory. Six Sigma is an error reduction methodology that has been successfully applied at Motorola and General Electric. Sigma (σ) is the mathematical symbol for standard deviation (SD). Sigma methodology can be applied wherever an outcome of a process has to be measured. A poor outcome is counted as an error or defect. This is quantified as defects per million (DPM). A six sigma process is one in which 99.999666% of the products manufactured are statistically expected to be free of defects. Six sigma concentrates, on regulating a process to 6 SDs, represents 3.4 DPM (defects per million) opportunities. It can be inferred that as sigma increases, the consistency and steadiness of the test improves, thereby reducing the operating costs. We aimed to gauge performance of our laboratory parameters by sigma metrics. Evaluation of sigma metrics in interpretation of parameter performance in clinical biochemistry. The six month internal QC (October 2012 to march 2013) and EQAS (external quality assurance scheme) were extracted for the parameters-Glucose, Urea, Creatinine, Total Bilirubin, Total Protein, Albumin, Uric acid, Total Cholesterol, Triglycerides, Chloride, SGOT, SGPT and ALP. Coefficient of variance (CV) were calculated from internal QC for these parameters. Percentage bias for these parameters was calculated from the EQAS. Total allowable errors were followed as per Clinical Laboratory Improvement Amendments (CLIA) guidelines. Sigma metrics were calculated from CV, percentage bias and total allowable error for the above mentioned parameters. For parameters - Total bilirubin, uric acid, SGOT, SGPT and ALP, the sigma values were found to be more than 6. For parameters - glucose, Creatinine, triglycerides, urea, the sigma values were found to be between 3 to 6. For parameters - total protein, albumin, cholesterol and chloride, the sigma values were found to be less than 3. ALP was the best

  14. A Model for Sigma Factor Competition in Bacterial Cells

    PubMed Central

    Mauri, Marco; Klumpp, Stefan

    2014-01-01

    Sigma factors control global switches of the genetic expression program in bacteria. Different sigma factors compete for binding to a limited pool of RNA polymerase (RNAP) core enzymes, providing a mechanism for cross-talk between genes or gene classes via the sharing of expression machinery. To analyze the contribution of sigma factor competition to global changes in gene expression, we develop a theoretical model that describes binding between sigma factors and core RNAP, transcription, non-specific binding to DNA and the modulation of the availability of the molecular components. The model is validated by comparison with in vitro competition experiments, with which excellent agreement is found. Transcription is affected via the modulation of the concentrations of the different types of holoenzymes, so saturated promoters are only weakly affected by sigma factor competition. However, in case of overlapping promoters or promoters recognized by two types of sigma factors, we find that even saturated promoters are strongly affected. Active transcription effectively lowers the affinity between the sigma factor driving it and the core RNAP, resulting in complex cross-talk effects. Sigma factor competition is not strongly affected by non-specific binding of core RNAPs, sigma factors and holoenzymes to DNA. Finally, we analyze the role of increased core RNAP availability upon the shut-down of ribosomal RNA transcription during the stringent response. We find that passive up-regulation of alternative sigma-dependent transcription is not only possible, but also displays hypersensitivity based on the sigma factor competition. Our theoretical analysis thus provides support for a significant role of passive control during that global switch of the gene expression program. PMID:25299042

  15. A model for sigma factor competition in bacterial cells.

    PubMed

    Mauri, Marco; Klumpp, Stefan

    2014-10-01

    Sigma factors control global switches of the genetic expression program in bacteria. Different sigma factors compete for binding to a limited pool of RNA polymerase (RNAP) core enzymes, providing a mechanism for cross-talk between genes or gene classes via the sharing of expression machinery. To analyze the contribution of sigma factor competition to global changes in gene expression, we develop a theoretical model that describes binding between sigma factors and core RNAP, transcription, non-specific binding to DNA and the modulation of the availability of the molecular components. The model is validated by comparison with in vitro competition experiments, with which excellent agreement is found. Transcription is affected via the modulation of the concentrations of the different types of holoenzymes, so saturated promoters are only weakly affected by sigma factor competition. However, in case of overlapping promoters or promoters recognized by two types of sigma factors, we find that even saturated promoters are strongly affected. Active transcription effectively lowers the affinity between the sigma factor driving it and the core RNAP, resulting in complex cross-talk effects. Sigma factor competition is not strongly affected by non-specific binding of core RNAPs, sigma factors and holoenzymes to DNA. Finally, we analyze the role of increased core RNAP availability upon the shut-down of ribosomal RNA transcription during the stringent response. We find that passive up-regulation of alternative sigma-dependent transcription is not only possible, but also displays hypersensitivity based on the sigma factor competition. Our theoretical analysis thus provides support for a significant role of passive control during that global switch of the gene expression program.

  16. 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

  17. Characterizing the magnetic field and spectral variability of the rigidly rotating magnetosphere star HD 345439

    NASA Astrophysics Data System (ADS)

    Hubrig, S.; Kholtygin, A. F.; Schöller, M.; Ilyin, I.

    2017-05-01

    A team involved in the Apache Point Observatory Galactic Evolution Experiment (APOGEE), one of the Sloan Digital Sky Survey III programmes, recently announced the discovery of two rare rigidly rotating magnetosphere stars, HD 345439 and HD 23478. Near-infrared spectra of these objects revealed emission-line behaviour identical to that previously discovered in the helium-strong star σ Ori E, which has a strong magnetic field and rotates fast. A single spectropolarimetric observation of HD 345439 with the FOcal Reducer low dispersion Spectrograph (FORS 2) at the Very Large Telescope (VLT) in 2014 over 88 min indicated that HD 345439 may host a strong, rapidly varying magnetic field. In this work, we present the results of our spectropolarimetric monitoring of this star with FORS 2, which revealed the presence of a strong longitudinal magnetic field dominated by a dipolar component. The analysis of spectral variability indicates an opposite behaviour of He and Si lines, which is usually attributed to differences in the distribution of surface He and Si abundance spots.

  18. Early development of sigma-receptor ligands.

    PubMed

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

    2011-01-01

    Sigma receptors (σ-1 and σ-2) are non-opioid proteins implicated in the pathophysiology of various neurological disorders and cancer. The σ-1 subtype is a chaperon protein widely distributed in the CNS and peripheral tissues. These receptors are involved in the modulation of K(+)- and Ca(2+)-dependent signaling cascades at the endoplasmic reticulum and modulation of neurotransmitter release. σ-1 receptors are emerging targets for the treatment of neurophychiatric diseases (schizophrenia and depression) and cocaine addiction. σ-2 receptors are lipid raft proteins. They are highly expressed on many tumor cells and hence considered potential targets for anticancer drugs. σ receptors bind to a diverse class of pharmacological compounds like cocaine, methamphetamine, benzomorphans like (±)-pentazocine, (±)-SKF-10,047 and endogenous neurosteroids and sphingolipids. In this review we focus on the early development of σ receptor-specific ligands and radiolabeling agents.

  19. Five years of photometry of Sigma Geminorum

    NASA Technical Reports Server (NTRS)

    Fried, R. E.; Vaucher, C. A.; Hopkins, J. L.; Sabia, J. D.; Krisciunas, K.; Chambliss, C. R.; Landis, H. J.; Eaton, J. A.; Hall, D. S.; Henry, G. W.

    1983-01-01

    Thirteen observatories have collaborated in obtaining five years of photoelectric photometry for the bright, K1 III RS CVn binary Sigma Geminorum. Except for one year, the light curve has exhibited two minima which are separated by approximately half a cycle. At the 1977.2 epoch of discovery one minimum was shallower, but as of 1982.2 they have become comparable in depth. During the 1979-80 season, the light curve changed shape rapidly, with the shallower minimum becoming as deep as the other within a period of no more than 80 days. The overall brightness range during the five years in V has been 4.13-4.29 mag, and it is found that the times of both minima can be fit with a photometric period of 19.423 days.

  20. Trifluoromethylsulfonyl derivatives of benzofuroxane and their anionic sigma-complexes

    SciTech Connect

    Yagupol'skii, L.M.; Gogoman, I.V.; Shchupak, G.M.; Boiko, V.N.

    1986-09-10

    Syntheses are reported for 4-nitro-6-trifluoromethylsulfonyl- and 4,6-bis(trifluoromethylsulfonyl)benzofuroxanes and their anionic sigma-complexes with hydroxide and methylate anions. In contrast to its 4,6-dinitro analog, 4,6-bis(trifluoromethylsulfonyl)benzofuroxane forms stable sigma-complexes with sodium acetate and sodium azide and has higher acidity by an order of magnitude.

  1. Automatisierte VHDL-Code-Generierung eines Delta-Sigma Modulators

    NASA Astrophysics Data System (ADS)

    Spilka, R.; Ostermann, T.

    2006-09-01

    Im vorliegenden Beitrag wird eine automatische Generierung des VHDL-Codes eines Delta-Sigma Modulators präsentiert. Die Koeffizientenmultiplikation wird hierbei durch Bit-Serielle-Addition durchgeführt. Mit Hilfe zweier neuer Matlab Funktionen wird der Systementwurf durch die bekannte Delta-Sigma Toolbox von R. Schreier erweitert und direkt synthesefähiger VHDL Code erzeugt.

  2. Conversations with Early Leaders of Eta Sigma Gamma

    ERIC Educational Resources Information Center

    Clark, Jeffrey K.; Seabert, Denise M.; Goldsmith, Mal

    2007-01-01

    Anniversaries are often a time to reflect on the past. With that in mind, interviews were conducted with early key leaders of Eta Sigma Gamma to explore their perspectives of the organization's growth and development as well as their hopes for the future of ESG. The individuals interviewed included the surviving founders of Eta Sigma Gamma, the…

  3. 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.

  4. Sigma-1 receptor: the novel intracellular target of neuropsychotherapeutic drugs.

    PubMed

    Hayashi, Teruo

    2015-01-01

    Sigma-1 receptor ligands have been long expected to serve as drugs for treatment of human diseases such as neurodegenerative disorders, depression, idiopathic pain, drug abuse, and cancer. Recent research exploring the molecular function of the sigma-1 receptor started unveiling underlying mechanisms of the therapeutic activity of those ligands. Via the molecular chaperone activity, the sigma-1 receptor regulates protein folding/degradation, ER/oxidative stress, and cell survival. The chaperone activity is activated or inhibited by synthetic sigma-1 receptor ligands in an agonist-antagonist manner. Sigma-1 receptors are localized at the endoplasmic reticulum (ER) membranes that are physically associated with the mitochondria (MAM: mitochondria-associated ER membrane). In specific types of neurons (e.g., those at the spinal cord), sigma-1 receptors are also clustered at ER membranes that juxtapose postsynaptic plasma membranes. Recent studies indicate that sigma-1 receptors, partly in sake of its unique subcellular localization, regulate the mitochondria function that involves bioenergetics and free radical generation. The sigma-1 receptor may thus provide an intracellular drug target that enables controlling ER stress and free radical generation under pathological conditions.

  5. 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.

  6. 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…

  7. REGULATION OF STAR FORMATION RATES IN MULTIPHASE GALACTIC DISKS: A THERMAL/DYNAMICAL EQUILIBRIUM MODEL

    SciTech Connect

    Ostriker, Eve C.; McKee, Christopher F.; Leroy, Adam K. E-mail: cmckee@astro.berkeley.ed

    2010-10-01

    We develop a model for the regulation of galactic star formation rates {Sigma}{sub SFR} in disk galaxies, in which interstellar medium (ISM) heating by stellar UV plays a key role. By requiring that thermal and (vertical) dynamical equilibrium are simultaneously satisfied within the diffuse gas, and that stars form at a rate proportional to the mass of the self-gravitating component, we obtain a prediction for {Sigma}{sub SFR} as a function of the total gaseous surface density {Sigma} and the midplane density of stars+dark matter {rho}{sub sd}. The physical basis of this relationship is that the thermal pressure in the diffuse ISM, which is proportional to the UV heating rate and therefore to {Sigma}{sub SFR}, must adjust until it matches the midplane pressure value set by the vertical gravitational field. Our model applies to regions where {Sigma} {approx}< 100 M{sub sun} pc{sup -2}. In low-{Sigma}{sub SFR} (outer-galaxy) regions where diffuse gas dominates, the theory predicts that {Sigma}{sub SFR{proportional_to}{Sigma}{radical}}({rho}{sub sd}). The decrease of thermal equilibrium pressure when {Sigma}{sub SFR} is low implies, consistent with observations, that star formation can extend (with declining efficiency) to large radii in galaxies, rather than having a sharp cutoff at a fixed value of {Sigma}. The main parameters entering our model are the ratio of thermal pressure to total pressure in the diffuse ISM, the fraction of diffuse gas that is in the warm phase, and the star formation timescale in self-gravitating clouds; all of these are (at least in principle) direct observables. At low surface density, our model depends on the ratio of the mean midplane FUV intensity (or thermal pressure in the diffuse gas) to the star formation rate, which we set based on solar-neighborhood values. We compare our results to recent observations, showing good agreement overall for azimuthally averaged data in a set of spiral galaxies. For the large flocculent spiral

  8. Could sigma receptor ligands be a treatment for methamphetamine addiction?

    PubMed

    Rodvelt, Kelli R; Miller, Dennis K

    2010-09-01

    Methamphetamine's effects are generally considered to be mediated via monoamine transporters; however, it has comparable affinity for sigma receptors. Sigma receptors influence the downstream dopamine systems that are targeted by methamphetamine treatment. Research investigating the effect of sigma receptor agonists on methamphetamine-associated neurochemical and behavioral properties remains controversial; however, the general trend indicates an enhancement of stimulant effects. In contrast, sigma receptor antagonists attenuate methamphetamine-induced neurotoxic and behavioral properties. Together, these studies highlight an important role for sigma receptors in methamphetamine's addictive properties and the consequences of methamphetamine intoxication. Additional research is necessary to elucidate the precise mechanisms underlying their involvement and their role as a potential target for anti-methamphetamine pharmacotherapies.

  9. SIGMA Final Report: Volume V, Part 4. The Design of SIGMA.

    DTIC Science & Technology

    1982-05-01

    sender , subject, date/time stamp, etc.--so that the message behind it is identifiable. It also specifies the nature of transmission, whether a message is...number, the new mail and alert counts, the load aerage, and the time of day. is generated and sent to the Driver. - Ithe user queue is not empty. the...deletes folders from the SIGMA folder database (DELETE-FOLDER). " It updates folders with delta file information (DELTA-UPDATE). * It creates inboxes

  10. A comparison of regional isentropic-sigma and sigma model simulations of the January 1979 Chicago blizzard

    NASA Technical Reports Server (NTRS)

    Zapotocny, Tom H.; Johnson, Donald R.; Reames, Fred M.

    1993-01-01

    In an initial effort in regional numerical weather prediction, results from the University of Wisconsin isentropic-sigma (UW theta-sigma) hybrid model and an 'identical' sigma model are compared. The two main objectives are to demonstrate the capability of the UW theta-sigma model for regional numerical weather prediction and to identify advantages of the hybrid model in simulating atmospheric water vapor transport and precipitation relative to the sigma model. The 72-h simulations produced by the two models extend over a region covering the western Pacific Ocean, North America, and the western Atlantic Ocean. The simulations begin at 0000 UTC 13 January 1979, a period during which an intense Chicago blizzard develops over the central United States. This period also includes the rapid development of a cyclone in the western Pacific Ocean. Results using the Global Weather Experiment (GWE) ECMWF level IIIB data as initial and verification data indicate that both models produce reasonable and similar 72-h simulations, with the UW theta-sigma model mass and momentum distributions being slightly more accurate than the sigma model. Of particular importance for the Chicago blizzard is that the UW theta-sigma model more accurately simulates water vapor transport northward from the Gulf of Mexico and westward from the Atlantic Ocean. As a result, the hybrid model more accurately simulates observed precipitation, especially over the northeastern U.S. and southeastern Canada.

  11. 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.

  12. A comparison of regional isentropic-sigma and sigma model simulations of the January 1979 Chicago blizzard

    NASA Technical Reports Server (NTRS)

    Zapotocny, Tom H.; Johnson, Donald R.; Reames, Fred M.

    1993-01-01

    In an initial effort in regional numerical weather prediction, results from the University of Wisconsin isentropic-sigma (UW theta-sigma) hybrid model and an 'identical' sigma model are compared. The two main objectives are to demonstrate the capability of the UW theta-sigma model for regional numerical weather prediction and to identify advantages of the hybrid model in simulating atmospheric water vapor transport and precipitation relative to the sigma model. The 72-h simulations produced by the two models extend over a region covering the western Pacific Ocean, North America, and the western Atlantic Ocean. The simulations begin at 0000 UTC 13 January 1979, a period during which an intense Chicago blizzard develops over the central United States. This period also includes the rapid development of a cyclone in the western Pacific Ocean. Results using the Global Weather Experiment (GWE) ECMWF level IIIB data as initial and verification data indicate that both models produce reasonable and similar 72-h simulations, with the UW theta-sigma model mass and momentum distributions being slightly more accurate than the sigma model. Of particular importance for the Chicago blizzard is that the UW theta-sigma model more accurately simulates water vapor transport northward from the Gulf of Mexico and westward from the Atlantic Ocean. As a result, the hybrid model more accurately simulates observed precipitation, especially over the northeastern U.S. and southeastern Canada.

  13. Symbiotic stars

    NASA Technical Reports Server (NTRS)

    Kafatos, M.; Michalitsianos, A. G.

    1984-01-01

    The physical characteristics of symbiotic star systems are discussed, based on a review of recent observational data. A model of a symbiotic star system is presented which illustrates how a cool red-giant star is embedded in a nebula whose atoms are ionized by the energetic radiation from its hot compact companion. UV outbursts from symbiotic systems are explained by two principal models: an accretion-disk-outburst model which describes how material expelled from the tenuous envelope of the red giant forms an inwardly-spiralling disk around the hot companion, and a thermonuclear-outburst model in which the companion is specifically a white dwarf which superheats the material expelled from the red giant to the point where thermonuclear reactions occur and radiation is emitted. It is suspected that the evolutionary course of binary systems is predetermined by the initial mass and angular momentum of the gas cloud within which binary stars are born. Since red giants and Mira variables are thought to be stars with a mass of one or two solar mass, it is believed that the original cloud from which a symbiotic system is formed can consist of no more than a few solar masses of gas.

  14. Sigma receptors as potential therapeutic targets for neuroprotection.

    PubMed

    Nguyen, Linda; Kaushal, Nidhi; Robson, Matthew J; Matsumoto, Rae R

    2014-11-15

    Sigma receptors comprise a unique family of proteins that have been implicated in the pathophysiology and treatment of many central nervous system disorders, consistent with their high level of expression in the brain and spinal cord. Mounting evidence indicate that targeting sigma receptors may be particularly beneficial in a number of neurodegenerative conditions including Alzheimer׳s disease, Parkinson׳s disease, stroke, methamphetamine neurotoxicity, Huntington׳s disease, amyotrophic lateral sclerosis, and retinal degeneration. In this perspective, a brief overview is given on sigma receptors, followed by a focus on common mechanisms of neurodegeneration that appear amenable to modulation by sigma receptor ligands to convey neuroprotective effects and/or restorative functions. Within each of the major mechanisms discussed herein, the neuroprotective effects of sigma ligands are summarized, and when known, the specific sigma receptor subtype(s) involved are identified. Together, the literature suggests sigma receptors may provide a novel target for combatting neurodegenerative diseases through both neuronal and glial mechanisms. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Application of Six Sigma towards improving surgical outcomes.

    PubMed

    Shukla, P J; Barreto, S G; Nadkarni, M S

    2008-01-01

    Six Sigma is a 'process excellence' tool targeting continuous improvement achieved by providing a methodology for improving key steps of a process. It is ripe for application into health care since almost all health care processes require a near-zero tolerance for mistakes. The aim of this study is to apply the Six Sigma methodology into a clinical surgical process and to assess the improvement (if any) in the outcomes and patient care. The guiding principles of Six Sigma, namely DMAIC (Define, Measure, Analyze, Improve, Control), were used to analyze the impact of double stapling technique (DST) towards improving sphincter preservation rates for rectal cancer. The analysis using the Six Sigma methodology revealed a Sigma score of 2.10 in relation to successful sphincter preservation. This score demonstrates an improvement over the previous technique (73% over previous 54%). This study represents one of the first clinical applications of Six Sigma in the surgical field. By understanding, accepting, and applying the principles of Six Sigma, we have an opportunity to transfer a very successful management philosophy to facilitate the identification of key steps that can improve outcomes and ultimately patient safety and the quality of surgical care provided.

  16. Sigma Receptors Suppress Multiple Aspects of Microglial Activation

    PubMed Central

    Hall Aaron, A.; Yelenis, Herrera; Ajmo Craig, T.; Javier, Cuevas; Pennypacker Keith, R.

    2009-01-01

    During brain injury, microglia become activated and migrate to areas of degenerating neurons. These microglia release pro-inflammatory cytokines and reactive oxygen species causing additional neuronal death. Microglia express high levels of sigma receptors, however, the function of these receptors in microglia and how they may affect the activation of these cells remain poorly understood. Using primary rat microglial cultures, it was found that sigma receptor activation suppresses the ability of microglia to rearrange their actin cytoskeleton, migrate, and release cytokines in response to the activators adenosine triphosphate (ATP), monocyte chemoattractant protein 1 (MCP-1), and lipopolysaccharide (LPS). Next, the role of sigma receptors in the regulation of calcium signaling during microglial activation was explored. Calcium fluorometry experiments in vitro show that stimulation of sigma receptors suppressed both transient and sustained intracellular calcium elevations associated with the microglial response to these activators. Further experiments showed that sigma receptors suppress microglial activation by interfering with increases in intracellular calcium. In addition, sigma receptor activation also prevented membrane ruffling in a calcium-independent manner, indicating that sigma receptors regulate the function of microglia via multiple mechanisms. PMID:19031439

  17. 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.

  18. Nonuniversal star formation efficiency in turbulent ISM

    DOE PAGES

    Semenov, Vadim A.; Kravtsov, Andrey V.; Gnedin, Nickolay Y.

    2016-07-29

    Here, we present a study of a star formation prescription in which star formation efficiency depends on local gas density and turbulent velocity dispersion, as suggested by direct simulations of SF in turbulent giant molecular clouds (GMCs). We test the model using a simulation of an isolated Milky Way-sized galaxy with a self-consistent treatment of turbulence on unresolved scales. We show that this prescription predicts a wide variation of local star formation efficiency per free-fall time,more » $$\\epsilon_{\\rm ff} \\sim 0.1 - 10\\%$$, and gas depletion time, $$t_{\\rm dep} \\sim 0.1 - 10$$ Gyr. In addition, it predicts an effective density threshold for star formation due to suppression of $$\\epsilon_{\\rm ff}$$ in warm diffuse gas stabilized by thermal pressure. We show that the model predicts star formation rates in agreement with observations from the scales of individual star-forming regions to the kiloparsec scales. This agreement is non-trivial, as the model was not tuned in any way and the predicted star formation rates on all scales are determined by the distribution of the GMC-scale densities and turbulent velocities $$\\sigma$$ in the cold gas within the galaxy, which is shaped by galactic dynamics. The broad agreement of the star formation prescription calibrated in the GMC-scale simulations with observations, both gives credence to such simulations and promises to put star formation modeling in galaxy formation simulations on a much firmer theoretical footing.« less

  19. Comments on HKT supersymmetric sigma models and their Hamiltonian reduction

    NASA Astrophysics Data System (ADS)

    Fedoruk, Sergey; Smilga, Andrei

    2015-05-01

    Using complex notation, we present new simple expressions for two pairs of complex supercharges in HKT (‘hyper-Kähler with torsion’) supersymmetric sigma models. The second pair of supercharges depends on the holomorphic antisymmetric ‘hypercomplex structure’ tensor {{I}jk} which plays the same role for the HKT models as the complex structure tensor for the Kähler models. When the Hamiltonian and supercharges commute with the momenta conjugate to the imaginary parts of the complex coordinates, one can perform a Hamiltonian reduction. The models thus obtained represent a special class of quasicomplex sigma models introduced recently by Ivanov and Smilga (2013 SIGMA 9 069)

  20. 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)

  1. 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.

  2. On the sigma-model of deformed special geometry

    NASA Astrophysics Data System (ADS)

    Lopes Cardoso, Gabriel; Véliz-Osorio, Alvaro

    2013-07-01

    We discuss the deformed sigma-model that arises when considering four-dimensional N=2 abelian vector multiplets in the presence of an arbitrary chiral background field. In addition, we allow for a class of deformations of special geometry by non-holomorphic terms. We analyze the geometry of the sigma-model in terms of intrinsic torsion classes. We show that, generically, the deformed geometry is non-Kähler. We illustrate our findings with an example. We also express the deformed sigma-model in terms of the Hesse potential that underlies the real formulation of special geometry.

  3. 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

  4. Sigma-1 receptor and inflammatory pain.

    PubMed

    Gris, Georgia; Cobos, Enrique José; Zamanillo, Daniel; Portillo-Salido, Enrique

    2015-06-01

    The sigma-1 receptor (Sig-1R) is a unique ligand-regulated molecular chaperone that interacts with several protein targets such as G protein-coupled receptors and ion channels to modulate their activity. Sig-1R is located in areas of the central and peripheral nervous system that are key to pain control. Previous preclinical studies have suggested a potential therapeutic use of Sig-1R antagonists for the management of neuropathic pain. Recent studies using pharmacological and genetic tools have explored the role of Sig-1R in inflammatory pain conditions. Mice lacking the Sig-1R have shown different patterns of phenotypic responses to inflammatory injury. Systemic or peripheral administration of several Sig-1R antagonists, including the selective Sig-1R antagonist S1RA, inhibited both mechanical and thermal hypersensitivity in several preclinical models of inflammatory pain. These recent studies are summarized in the present commentary. Central and peripheral pharmacological blockade of Sig-1R could be an effective option to treat inflammatory pain.

  5. Chameleon stars

    SciTech Connect

    Dzhunushaliev, Vladimir; Folomeev, Vladimir; Singleton, Douglas

    2011-10-15

    We consider a gravitating spherically symmetric configuration consisting of a scalar field nonminimally coupled to ordinary matter in the form of a perfect fluid. For this system we find static, regular, asymptotically flat solutions for both relativistic and nonrelativistic cases. It is shown that the presence of the nonminimal interaction leads to substantial changes both in the radial matter distribution of the star and in the star's total mass. A simple stability test indicates that, for the choice of parameters used in the paper, the solutions are unstable.

  6. Rainbow's stars

    NASA Astrophysics Data System (ADS)

    Garattini, Remo; Mandanici, Gianluca

    2017-01-01

    In recent years, a growing interest in the equilibrium of compact astrophysical objects like white dwarf and neutron stars has been manifested. In particular, various modifications due to Planck-scale energy effects have been considered. In this paper we analyze the modification induced by gravity's rainbow on the equilibrium configurations described by the Tolman-Oppenheimer-Volkoff (TOV) equation. Our purpose is to explore the possibility that the rainbow Planck-scale deformation of space-time could support the existence of different compact stars.

  7. The C2 Ballik-Ramsay transitions in carbon stars

    NASA Technical Reports Server (NTRS)

    Goorvitch, David

    1990-01-01

    The bands of C2 are an important source of opacity in the near-infrared spectral region of carbon stars. In the 2 micron spectral region, the Delta v = -1 and -2 transitions of the Ballik-Ramsay b 3Sigma(g)(-) - a 3Pi(u) system are especially important. A general method for calculating highly accurate transition parameters of the Ballik-Ramsay band is presented. This method allows the easy calculation of the satellite lines and the forbidden lines resulting from the perturbation of the upper b 3Sigma(g)(-) state by the X 1Sigma(0)(+) state. Included in the calculation is the effect of the isotopic molecules (C-12)2, (C-12)(C-13), and (C-13)2. Three consistency tests of the calculated strengths are presented. A comparison of synthetic spectra is made with an observed spectrum of WZ Cas in the 3940/cm spectral region.

  8. Sigma1 recognition sites in rabbit iris-ciliary body: topical sigma1-site agonists lower intraocular pressure.

    PubMed

    Bucolo, C; Campana, G; Di Toro, R; Cacciaguerra, S; Spampinato, S

    1999-06-01

    In this study, we examined the presence of sigma1 and sigma2 sites in the rabbit iris-ciliary body by receptor binding and investigated their effects on intraocular pressure (IOP) in albino rabbits. The iris-ciliary body has binding sites for the sigma1-site agonist [3H](+)-pentazocine (Kd = 4.6 nM; Bmax = 212 fmol/mg protein) and sigma2 sites labeled with [3H]1,3-di-o-tolylguanidine (DTG) (Kd = 8. 2 nM; Bmax = 1120 fmol/mg protein). In competition binding studies, (+)-pentazocine and the sigma antagonist NE-100 displayed high affinity for sigma1 sites (Ki = 2.1 and 2.4 nM, respectively), whereas (+)-N-allylnormetazocine (NANM) was less potent (Ki = 178 nM). Unilateral topical (+)-pentazocine (0.01-0.1%) caused a significant dose-related reduction of IOP in ocular normotensive rabbits and in the alpha-chymotrypsin model of ocular hypertension. (+)-NANM was less potent than (+)-pentazocine. Neither compound altered the IOP of the contralateral eye, and their hypotensive activity was blocked by NE-100 that, by itself, had no effect on IOP. (-)-Pentazocine, (-)-NANM, and DTG had no effect on IOP. DTG prevented the hypotensive effect of (+)-pentazocine, suggesting that it acts as a sigma1-site antagonist. sigma-Site ligands did not affect pupil diameter or cause ocular inflammation. Topical [3H](+)-pentazocine reaches the intraocular tissues within 30 min, and its uptake in the iris-ciliary body and retina was significantly reduced by topical pretreatment with NE-100, as expected for a receptor-specific agent. Reverse-phase HPLC confirmed the presence of intact (+)-pentazocine in iris-ciliary body homogenates. sigma1-Site agonists may offer a novel class of agents potentially effective in the control of ocular hypertension.

  9. Coordinated Ginga, IUE, and VLA observations of stellar activity in Sigma(2) Coronae Borealis

    NASA Technical Reports Server (NTRS)

    Stern, R. A.; Uchida, Y.; Walter, F.; Vilhu, O.; Hannikainen, D.; Brown, A.; Veale, A.; Haisch, B. M.

    1992-01-01

    Observations of the active cool star binary system Sigma(2) Corona Borealis with the Large Area Counters on the Ginga X-ray satellite over 2.5 d, or about two orbital periods, are reported. Throughout the observations, Sigma(2) CrB exhibited X-ray variability on time scales ranging from tens of minutes to hours. The X-ray light curve shows evidence of flaring during the course of the observations. The summed X-ray pulse height spectrum from flaring events compared with similar spectra from quiescent periods indicates an increase in coronal temperature. Periodogram analysis of the entire X-ray light curve shows a possible periodicity at about 0.40-0.44 d, with no strong signal at the orbital period or 1/2 of the orbital period. Coordinated multiwavelength observations of IUE and the VLA indicate both UV and microwave flaring during one X-ray outburst. The quiescent microwave spectrum is not consistent with a thermal gyrosynchrotron process; nonthermal gyrosynchrotron radiation is argued to be the most likely emission process.

  10. 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.

  11. 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.

  12. Morning Star

    NASA Image and Video Library

    2013-03-04

    Dawn on Saturn is greeted across the vastness of interplanetary space by the morning star, Venus, in this image from NASA Cassini spacecraft. Venus appears just off the edge of the planet directly above the white streak of Saturn G ring.

  13. 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.

  14. Blue shifts vs red shifts in sigma-hole bonding.

    PubMed

    Murray, Jane S; Concha, Monica C; Lane, Pat; Hobza, Pavel; Politzer, Peter

    2008-08-01

    Sigma-hole bonding is a noncovalent interaction between a region of positive electrostatic potential on the outer surface of a Group V, VI, or VII covalently-bonded atom (a sigma-hole) and a region of negative potential on another molecule, e.g., a lone pair of a Lewis base. We have investigated computationally the occurrence of increased vibration frequencies (blue shifts) and bond shortening vs decreased frequencies (red shifts) and bond lengthening for the covalent bonds to the atoms having the sigma-holes (the sigma-hole donors). Both are possible, depending upon the properties of the donor and the acceptor. Our results are consistent with models that were developed earlier by Hermansson and by Qian and Krimm in relation to blue vs red shifting in hydrogen bond formation. These models invoke the derivatives of the permanent and the induced dipole moments of the donor molecule.

  15. An integrated delta-sigma based IIR filter

    NASA Astrophysics Data System (ADS)

    Au, Dennis Kin-Wah

    Delta-sigma based infinite impulse response (IIR) filters are a recently developed circuit technique for efficiently realizing IIR filters operating directly on oversampled delta-sigma modulated signals. The design and single-chip implementation of a fifth-order delta-sigma based IIR filter are described. The filter coefficients are fully programmable and with the use of a structure that is inherently scaled for dynamic range, good filter performance is maintained over a wide variety of transfer functions. To eliminate multi-bit multiplications, five second-order digital delta-sigma modulators were used and dynamic range improvement was obtained through the use of multi-bit quantizers in these modulators. The filter was implemented as a very large scale integration chip using 1.2 micron complementary metal oxide semiconductor technology, occupying an area of 4,355 by 5,962 square microns. Simulations indicate that the clock range should operate up to 45 MHz.

  16. 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.

  17. Astronaut Walter Schirra being removed from his Sigma 7 capsule

    NASA Image and Video Library

    1962-10-03

    S62-06148 (3 Oct. 1962) --- Close-up view of Mercury-Atlas 8 (MA-8) astronaut Walter Schirra being removed from his Sigma 7 capsule by Navy personnel. Schirra has just removed his helmet. Photo credit: NASA

  18. 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.

  19. 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.

  20. New evaluation of the {pi}N{sigma} term

    SciTech Connect

    Hite, Gerald E.; Kaufmann, William B.; Jacob, Richard J.

    2005-06-01

    A new evaluation of the {pi}N{sigma} term is presented that incorporates recent s-channel phase shifts and t-channel {pi}{pi} phase shifts. We also introduce analyticity-based extrapolation techniques that, along with standard dispersion relation methods, produce a more reliable extrapolation to the Cheng-Dashen point. A recent George Washington University (GWU) phase-shift analysis leads to a {sigma} term of 81{+-}6 MeV.

  1. The 2Sigma(+)-2Pi separation in KO

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Partridge, Harry; Dyall, Kenneth G.

    1992-01-01

    The 2Sigma(+)-2Pi separation in KO is investigated using large basis sets and high levels of correlation treatment. Relativistic effects are included at the Dirac-Fock level and reduce the separation only slightly. The basis set superposition error is considered in detail. On the basis of these calculations, our best estimate places the 2Pi3/2 state about 200/cm above the ground 2Sigma(+) state, in agreement with our previous estimate.

  2. 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.

  3. On Addition Formulae for Sigma Functions of Telescopic Curves

    NASA Astrophysics Data System (ADS)

    Ayano, Takanori; Nakayashiki, Atsushi

    2013-06-01

    A telescopic curve is a certain algebraic curve defined by m-1 equations in the affine space of dimension m, which can be a hyperelliptic curve and an (n,s) curve as a special case. We extend the addition formulae for sigma functions of (n,s) curves to those of telescopic curves. The expression of the prime form in terms of the derivative of the sigma function is also given.

  4. Improving laboratory data entry quality using Six Sigma.

    PubMed

    Elbireer, Ali; Le Chasseur, Julie; Jackson, Brooks

    2013-01-01

    The Uganda Makerere University provides clinical laboratory support to over 70 clients in Uganda. With increased volume, manual data entry errors have steadily increased, prompting laboratory managers to employ the Six Sigma method to evaluate and reduce their problems. The purpose of this paper is to describe how laboratory data entry quality was improved by using Six Sigma. The Six Sigma Quality Improvement (QI) project team followed a sequence of steps, starting with defining project goals, measuring data entry errors to assess current performance, analyzing data and determining data-entry error root causes. Finally the team implemented changes and control measures to address the root causes and to maintain improvements. Establishing the Six Sigma project required considerable resources and maintaining the gains requires additional personnel time and dedicated resources. After initiating the Six Sigma project, there was a 60.5 percent reduction in data entry errors from 423 errors a month (i.e. 4.34 Six Sigma) in the first month, down to an average 166 errors/month (i.e. 4.65 Six Sigma) over 12 months. The team estimated the average cost of identifying and fixing a data entry error to be $16.25 per error. Thus, reducing errors by an average of 257 errors per month over one year has saved the laboratory an estimated $50,115 a year. The Six Sigma QI project provides a replicable framework for Ugandan laboratory staff and other resource-limited organizations to promote quality environment. Laboratory staff can deliver excellent care at a lower cost, by applying QI principles. This innovative QI method of reducing data entry errors in medical laboratories may improve the clinical workflow processes and make cost savings across the health care continuum.

  5. 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.

  6. Six sigma critical success factors in manufacturing industries

    NASA Astrophysics Data System (ADS)

    Mustafa, Zainol; Jamaluddin, Z.

    2017-04-01

    The success of Six Sigma implementation is known to depend on a number of contributing factors. The purpose of this paper is to explore Six Sigma critical success factors (CSFs) in the context of Malaysian manufacturing organizations. Although Six Sigma success factors have been abundantly researched in the global context, in this paper, a maiden attempt is made to identify, through an extensive literature review, the CSFs for Six Sigma implementation followed by their validation using primary data collection from Malaysian manufacturing companies. A total of 33 indicators have thus been compiled through an extensive literature review which then been grouped into 6 contributing factors. These contributing success factors are then validated through an empirical research of selected Malaysian manufacturing companies at various stages of implementation of the Six Sigma process improvement methodology. There has been an overemphasis on the role and commitment of the management in the success of a Six Sigma program. Though it is undoubted, certain other factors also play an equally important role in ensuring that the Six Sigma programs are successful. The factor analysis of CSFs of the Malaysian manufacturing organizations selected in this study demonstrates that the top factor is a composite factor showing combination of the ability of the project teams to use the process management on quality initiative and a training using a proper analysis in problem solving. The CSFs extracted through the factor analysis could provide a basis for manufacturing organizations embarking on the Six Sigma journey to look beyond just management involvement. Thus, one can develop an integrated framework of other factors as outlined and give them appropriate priority and focus.

  7. 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.

  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. 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.

  10. The cholinergic system, sigma-1 receptors and cognition.

    PubMed

    van Waarde, Aren; Ramakrishnan, Nisha K; Rybczynska, Anna A; Elsinga, Philip H; Ishiwata, Kiichi; Nijholt, Ingrid M; Luiten, Paul G M; Dierckx, Rudi A

    2011-08-10

    This article provides an overview of present knowledge regarding the relationship between the cholinergic system and sigma-1 receptors, and discusses potential applications of sigma-1 receptor agonists in the treatment of memory deficits and cognitive disorders. Sigma-1 receptors, initially considered as a subtype of the opioid family, are unique ligand-regulated molecular chaperones in the endoplasmatic reticulum playing a modulatory role in intracellular calcium signaling and in the activity of several neurotransmitter systems, particularly the cholinergic and glutamatergic pathways. Several central nervous system (CNS) drugs show high to moderate affinities for sigma-1 receptors, including acetylcholinesterase inhibitors (donepezil), antipsychotics (haloperidol, rimcazole), selective serotonin reuptake inhibitors (fluvoxamine, sertraline) and monoamine oxidase inhibitors (clorgyline). These compounds can influence cognitive functions both via their primary targets and by activating sigma-1 receptors in the CNS. Sigma-1 agonists show powerful anti-amnesic and neuroprotective effects in a large variety of animal models of cognitive dysfunction involving, among others (i) pharmacologic target blockade (with muscarinic or NMDA receptor antagonists or p-chloroamphetamine); (ii) selective lesioning of cholinergic neurons; (iii) CNS administration of β-amyloid peptides; (iv) aging-induced memory loss, both in normal and senescent-accelerated rodents; (v) neurodegeneration induced by toxic compounds (CO, trimethyltin, cocaine), and (vi) prenatal restraint stress.

  11. A prototypical Sigma-1 receptor antagonist protects against brain ischemia.

    PubMed

    Schetz, John A; Perez, Evelyn; Liu, Ran; Chen, Shiuhwei; Lee, Ivan; Simpkins, James W

    2007-11-21

    Previous studies indicate that the Sigma-1 ligand 4-phenyl-1-(4-phenylbutyl) piperidine (PPBP) protects the brain from ischemia. Less clear is whether protection is mediated by agonism or antagonism of the Sigma-1 receptor, and whether drugs already in use for other indications and that interact with the Sigma-1 receptor might also prevent oxidative damage due to conditions such as cerebral ischemic stroke. The antipsychotic drug haloperidol is an antagonist of Sigma-1 receptors and in this study it potently protects against oxidative stress-related cell death in vitro at low concentrations. The protective potency of haloperidol and a number of other butyrophenone compounds positively correlate with their affinity for a cloned Sigma-1 receptor, and the protection is mimicked by a Sigma-1 receptor-selective antagonist (BD1063), but not an agonist (PRE-084). In vivo, an acute low dose (0.05 mg/kg s.c.) of haloperidol reduces by half the ischemic lesion volume induced by a transient middle cerebral artery occlusion. These in vitro and in vivo pre-clinical results suggest that a low dose of acutely administered haloperidol might have a novel application as a protective agent against ischemic cerebral stroke and other types of brain injury with an ischemic component.

  12. sigma-1 receptors in major depression and anxiety.

    PubMed

    Kulkarni, Shrinivas K; Dhir, Ashish

    2009-07-01

    Major depression and anxiety are two of the major psychiatric disorders that have some overlapping pathophysiologies, the most significant being the dysfunction in the monoaminergic, GABAergic and glutamatergic systems. A large number of drugs that alter these neurotransmitter levels/systems are effective in the treatment of major depression and anxiety. However, full remission of the clinical symptoms has not been achieved, perhaps owing to the complex pathophysiology of the diseases. Thus, the search for newer targets and target-specific drugs continues. Recently, the role of sigma-receptors, particularly the sigma-1 receptor subtype, has been identified as a target for the pathophysiology of neuropsychiatric disorders, and sigma-1 receptor modulators are considered to be the drugs of the future for the treatment of major depression and anxiety. The present review attempts to discuss the role of sigma-1 receptors in the pathophysiology of major depression and anxiety and also tries to position the use of its receptor modulators in the treatment of these two major disorders. The role of sigma-1 receptors in the mechanism of antidepressant action of venlafaxine, bupropion, neurosteroids and one of the herbal antidepressants, berberine, is reviewed. Although, sigma-1 receptor modulators may be future therapeutic options, either as individual agents or adjuvants in the treatment of mental disorders, the topic needs further preclinical and clinical exploration.

  13. An unusual primary sigma factor in the Bacteroidetes phylum.

    PubMed

    Vingadassalom, Didier; Kolb, Annie; Mayer, Claudine; Rybkine, Tania; Collatz, Ekkehard; Podglajen, Isabelle

    2005-05-01

    The presence of housekeeping gene promoters with a unique consensus sequence in Bacteroides fragilis, previously described by Bayley et al. (2000, FEMS Microbiol Lett 193: 149-154), suggested the existence of a particular primary sigma factor. The single rpoD-like gene observed in the B. fragilis genome, and similarly in those of other members of the Bacteroidetes phylum, was found to be essential. It encodes a protein, sigma(ABfr), of only 32.7 kDa that is produced with equal abundance during all phases of growth and was concluded to be the primary sigma factor. sigma(ABfr) and its orthologues in the Bacteroidetes are unusual primary sigma factors in that they lack region 1.1, have a unique signature made up of 29 strictly identical amino acids and are the only RpoD factors that cluster with the RpoS factors. Although binding to the Escherichia coli core RNA polymerase, sigma(ABfr) does not support transcription initiation from any promoter when it is part of the heterologous holoenzyme, while in the reconstituted homologous holoenzyme it does so only from typical B. fragilis, including rrs, promoters but not from the lacUV5 or RNA I promoters.

  14. 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.

  15. Radial Velocity Variability of mid-F Dwarf Stars

    NASA Astrophysics Data System (ADS)

    Cochran, W. D.; Hatzes, A. P.

    1994-05-01

    The McDonald Observatory Planetary Search program has been obtaining high precision (sigma ~ 10ms(-1) ) observations of a sample of 36 slowly rotating F, G, and K dwarfs since the fall of 1987. The primary purpose of this survey has been to detect sub-stellar companions to these stars. Most of the survey stars seem to have a level of intrinsic stellar radial velocity variability of about 20ms(-1) or less. However, the four stars of type F6 and earlier all seem to show significantly larger intrinsic variability of 40ms(-1) or more. These stars are pi (3) Orionis (F6V), alpha Canis Minoris A (F5IV-V), theta Ursae Majoris, and gamma Serpens. Stars of spectral type F8 and later do not seem to show this large level of radial velocity variability. One star of type F7V has recently been added to the survey, but we do not yet have sufficient data on it to determine its level of intrinsic variability. We present the observational data on these variable mid-F dwarfs, along with statistical analysis of the data in order to determine possible periodicities within the data. It is possible that these stars may represent the extreme ``tail end'' of the cool delta Scuti stars, or they may be a new class of variable stars in their own right.

  16. Compact non-thermal radio emission from B-peculiar stars

    NASA Technical Reports Server (NTRS)

    Phillips, R. B.; Lestrade, J.-F.

    1988-01-01

    Some stars hotter than 10,000 K show propensity for unusual surface abundances and excessive magnetic fields. These peculiar stars, Ap and Bp in the spectral nomenclature, show unusually prominent absorption lines of heavier elements. Rapid rotation and strong magnetic fields are revealed by line shapes and Zeeman splitting. VLBI is here used to directly probe the source size and brightness temperature of weak radio emission recently discovered from two isolated Bp stars, sigma Orionis E and HD37017. The emitting zone for each star is no more than 6 stellar diameters in extent, reflecting brightness temperatures of more than one billion K. Such high surface brightness resembles gyrosynchrotron radiation from mildly relativistic electrons trapped in the strong magnetic fields surrounding these stars. Compact radio radiation from these two stars presents new opportunities for probing the physical environments of early-type stars and for precise radio astrometry.

  17. The energy dependence of the pp {yields} K{sup +}n{Sigma}{sup +} reaction

    SciTech Connect

    Valdau, Yu.

    2011-10-24

    The energy dependence of the total cross section for the pp {yields} K{sup +}n{Sigma}{sup +} reaction has been investigated at the magnetic spectrometer COSY-ANKE. Signals from the production of the {Sigma}{sup +} hyperon were searched for in three simultaneously measured spectra. The values obtained for the total production cross section {sigma}({Sigma}{sup +}) are slightly below those of {sigma}({Sigma}{sup 0}) at the same excess energies. They follow a phase space dependence and do not show any evidence for strong threshold effects or a significant n{Sigma}{sup +} final state interaction.

  18. 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.

  19. Sigma-1 Receptors and Neurodegenerative Diseases: Towards a Hypothesis of Sigma-1 Receptors as Amplifiers of Neurodegeneration and Neuroprotection.

    PubMed

    Nguyen, Linda; Lucke-Wold, Brandon P; Mookerjee, Shona; Kaushal, Nidhi; Matsumoto, Rae R

    2017-01-01

    Sigma-1 receptors are molecular chaperones that may act as pathological mediators and targets for novel therapeutic applications in neurodegenerative diseases. Accumulating evidence indicates that sigma-1 ligands can either directly or indirectly modulate multiple neurodegenerative processes, including excitotoxicity, calcium dysregulation, mitochondrial and endoplasmic reticulum dysfunction, inflammation, and astrogliosis. In addition, sigma-1 ligands may act as disease-modifying agents in the treatment for central nervous system (CNS) diseases by promoting the activity of neurotrophic factors and neural plasticity. Here, we summarize their neuroprotective and neurorestorative effects in different animal models of acute brain injury and chronic neurodegenerative diseases, and highlight their potential role in mitigating disease. Notably, current data suggest that sigma-1 receptor dysfunction worsens disease progression, whereas enhancement amplifies pre-existing functional mechanisms of neuroprotection and/or restoration to slow disease progression. Collectively, the data support a model of the sigma-1 receptor as an amplifier of intracellular signaling, and suggest future clinical applications of sigma-1 ligands as part of multi-therapy approaches to treat neurodegenerative diseases.

  20. Star clusters

    NASA Astrophysics Data System (ADS)

    Labhardt, Lukas; Binggeli, Bruno

    Star clusters are at the heart of astronomy, being key objects for our understanding of stellar evolution and galactic structure. Observations with the Hubble Space Telescope and other modern equipment have revealed fascinating new facts about these galactic building blocks. This book provides two comprehensive and up-to-date, pedagogically designed reviews on star clusters by two well-known experts in the field. Bruce Carney presents our current knowledge of the relative and absolute ages of globular clusters and the chemical history of our Galaxy. Bill Harris addresses globular clusters in external galaxies and their use as tracers of galaxy formation and cosmic distance indicators. The book is written for graduate students as well as professionals in astronomy and astrophysics.

  1. Christmas star.

    NASA Astrophysics Data System (ADS)

    Biała, J.

    There are continuous attempts to identify the legendary Christmas Star with a real astronomical event accompanying the birth of Jesus from Nazareth. Unfortunately, the date of birth is difficult to establish on the basis of historical records with better accuracy than a few years. During that period a number of peculiar astronomical events were observed and it seem to be impossible to identify the right one unambiguously.

  2. 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.

  3. Neutron Stars

    NASA Astrophysics Data System (ADS)

    van den Heuvel, Ed

    Radio pulsars are unique laboratories for a wide range of physics and astrophysics. Understanding how they are created, how they evolve and where we find them in the Galaxy, with or without binary companions, is highly constraining of theories of stellar and binary evolution. Pulsars' relationship with a recently discovered variety of apparently different classes of neutron stars is an interesting modern astrophysical puzzle which we consider in Part I of this review. Radio pulsars are also famous for allowing us to probe the laws of nature at a fundamental level. They act as precise cosmic clocks and, when in a binary system with a companion star, provide indispensable venues for precision tests of gravity. The different applications of radio pulsars for fundamental physics will be discussed in Part II. We finish by making mention of the newly discovered class of astrophysical objects, the Fast Radio Bursts, which may or may not be related to radio pulsars or neutron stars, but which were discovered in observations of the latter.

  4. Periodic spectrum variations in helium-rich stars

    NASA Technical Reports Server (NTRS)

    Walborn, N. R.

    1982-01-01

    Spectroscopic observations of four helium-rich stars are presented. In HD 37776, antiphase variations of Si III and He I have been found, which represent another point of similarity to the Ap phenomenon. The remarkable H-alpha emission variations in Sigma Ori E are illustrated with uniform phase coverage, and strict periodicity over a five-year interval is shown. A radial-velocity study of HD 64740 shows constancy to within the accuracy of the observations. Finally, Delta Ori B is confirmed as a helium-rich star.

  5. Spectral classification of stars using synthetic model atmospheres

    NASA Astrophysics Data System (ADS)

    Bertone, E.; Buzzoni, A.

    2001-09-01

    We devised a straightforward procedure to derive the atmospheric fundamental parameters of stars across the different MK spectral types by comparing mid-resolution spectroscopic observations with theoretical grids of synthetic spectra. The results of a preliminary experiment, by matching the Gunn & Stryker (1983) and Jacoby et al. (1984) spectrophotometric atlases with the Kurucz (1995) models, are briefly discussed. For stars in the A-K spectral range, effective temperature is obtained within a 1-2% relative uncertainty (at 2-sigma confidence level). This value raises to 4-5% for the hottest stars in the samples (O-B spectral types). A poorer fit is obtained throughout for stars cooler than 4000 K mainly due to the limiting input physics in the Kurucz models.

  6. Time variations of UV emission features of Be stars

    NASA Technical Reports Server (NTRS)

    Bahng, J. D. R.

    1975-01-01

    The UV spectra of three Be stars (gamma Cas, sigma Tau, eta Cen) were studied. Of the six Be stars observed in the first four lines of the Balmer series, three stars showed at least one of the Balmer lines to be variable in the equivalent width amounting to a few percent with time scales of 3 to 30 minutes. Photoelectric spectrum scans of five southern Wolf-Rayet stars showed night-to-night variations. A simple model is proposed to account for the behavior of these emission lines. Scans of gamma square Vel showed rapid variations of emission strengths of He II 4686 and C III - IV 4650. These variations have time scales of 1 minute and longer. Night-to-night variations were also found. Scans of four Be stars in H alpha showed a definite variation of 3 to 4 percent, with time scales of 1 minute and longer in sigma Tau. In 48 Per and kappa Dra the variations are not as well established. No variation of any significance was found for nu Gem.

  7. 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.

  8. '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.

  9. '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.

  10. 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

  11. 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.

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

    USDA-ARS?s Scientific Manuscript database

    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...

  13. Strings as sigma models and in the tensionless limit

    NASA Astrophysics Data System (ADS)

    Persson, Jonas

    2007-05-01

    This thesis considers two different aspects of string theory, the tensionless limit of the string and supersymmetric sigma models. The tensionless limit is used to find a IIB supergravity background generated by a tensionless string. Quantization of the tensionless string in a pp-wave background is performed and the tensionless limit is found to commute with quantization. Further, the sigma model with N=(2,2) extended world-sheet supersymmetry is considered and the requirement on the target space to have a bi-Hermitean geometry is reviewed. It is shown that the equivalence between bi-Hermitean geometry and generalized Kahler follows, in this context, from the equivalence between the Lagrangian- and Hamiltonian formulation of the model. Moreover, the explicit T-duality transformation in the Hamiltonian formulation of the sigma model is constructed and shown to be a symplectomorphism. Under certain assumptions, the amount of extended supersymmetry present in the sigma model is shown to be preserved under T-duality. Further, by requiring N=(2,2) extended supersymmetry in a first order formulation of the sigma model an intriguing geometrical structure arises and in a special case generalized complex geometry is found to be contained in the new framework.

  14. 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.

  15. Development of Benzophenone-Alkyne Bifunctional Sigma Receptor Ligands

    PubMed Central

    Guo, Lian-Wang; Hajipour, Abdol R.; Karaoglu, Kerim; Mavlyutov, Timur A.; Ruoho, Arnold E.

    2012-01-01

    Sigma (σ) receptors represent unique non-opioid binding sites that are associated with a broad range of disease states. Sigma-2 receptors provide a promising target for diagnostic imaging and pharmacological interventions to curb tumor progression. Most recently, the progesterone receptor (PGRMC1, 25 kDa) has been identified to contain σ2 receptor-like binding properties, highlighting the need to understand the biological function of an 18-kDa protein that exhibits σ2-like photoaffinity labeling (herein denoted as σ2-18k) but the amino acid sequence of which is not known. In order to provide novel tools for the study of the σ2-18k protein, we have developed bifunctional sigma receptor ligands that bear a benzophenone photo-crosslinking moiety and an alkyne group, to which an azide-containing biotin affinity tag can be covalently attached via click chemistry following photo-crosslink. While several compounds showed favorable σ2 binding properties, compound 22 exhibited the highest affinity (2 nM) and the greatest potency in blocking photolabeling of the σ2-18k by a radioactive photoaffinity ligand. Thus, these benzophenone-alkyne sigma receptor ligands may be amenable for studying the σ2-18k protein via chemical biology approaches. To our knowledge, these compounds represent the first reported benzophenone-containing clickable sigma receptor ligands, which may potentially serve broad applications by “plugging” in various tags. PMID:23001760

  16. 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

  17. Can Six Sigma be the "cure" for our "ailing" NHS?

    PubMed

    Antony, Jiju; Downey-Ennis, Kay; Antony, Frenie; Seow, Chris

    2007-01-01

    The purpose of this research is to analyse whether Six Sigma business strategy can be used to improve the financial and operational performance of the NHS. The paper will also look at some of the major challenges and barriers in the implementation of this powerful process improvement strategy within the healthcare sector. This paper discusses whether Six Sigma DMAIC methodology can be a useful and disciplined approach to tackle process- and quality-related problems in the NHS. The paper presents some key findings from other researchers in the field, followed by some comments on whether Six Sigma is a useful approach to be considered by the NHS for cost reduction and defect reduction strategies. The paper illustrates the point that Six Sigma is not confined just to manufacturing industry, rather it is equally applicable to service industry, especially the healthcare and financial sectors. The application of Six Sigma in the UK health sector is relatively new and the purpose of the paper is to increase the awareness of this powerful business strategy in healthcare discipline.

  18. Can the sigma-1 receptor agonist fluvoxamine prevent schizophrenia?

    PubMed

    Hashimoto, Kenji

    2009-12-01

    In the past decade there has been increasing interest in the potential benefit of early pharmacological intervention in schizophrenia. Patients with schizophrenia show nonpsychotic and nonspecific prodromal symptoms (e.g., depression and cognitive deficits) for several years preceding the onset of frank psychosis. Several studies have demonstrated that medication with atypical antipsychotic drugs in people with prodromal symptoms may reduce the risk of subsequent transition to schizophrenia. Furthermore, a naturalistic treatment study in young people with prodromal symptoms demonstrated that medication with antidepressants could prevent the development of psychosis. Although the sample in this study was small, the results were striking. Some antidepressants, including selective serotonin reuptake inhibitors (SSRIs), had high to moderate affinities at the endoplasmic reticulum protein sigma-1 receptors, which are implicated in neuroprotection and neuronal plasticity. Among all antidepressants, fluvoxamine was the most potent sigma-1 receptor agonist. Since the effects of fluroxaming were antagonized by the selective sigma-1 receptor antagonist NE-100. Based on the role of sigma-1 receptors in the pathophysiology of cognition and depression, the author would like to propose a hypothesis that SSRIs (e.g., fluvoxamine) with sigma-1 receptor agonism may reduce the risk of subsequent transition to schizophrenia.

  19. How to reduce sigma in offshore pipe fabrications

    SciTech Connect

    Still, J.

    1999-11-01

    The use of stainless steel for offshore oil and gas applications has increased dramatically over the last 20 years. Stainless steels fall into a number of categories depending on the composition and microstructure formed after heat treatment. Selection of pipe materials for offshore applications is dependent on the product to be carried. Austenitic and ferritic/austenitic (duplex) stainless steels are commonly used for process and utility piping systems offshore, whereas martensitic and ferritic are restricted to specific applications. Reference to sigma in offshore welding specifications has been mixed. Previously, the identification of sigma was wither not quoted or stated as being not permitted. However, achieving zero sigma content in duplex stainless steel welds and HAZs is questionable, particularly in steels and weld metals having a high chromium and molybdenum content. In the real world, how does one ensure that production welds performed offshore are free of sigma--or have a limited volume fraction of it--without having to constantly monitor welder performance? This review examines the difficulties and controls required to limit the presence of sigma in austenitic and duplex weld metals and HAZs associated with offshore piping and pipeline systems. Materials described here are those manufactured using contemporary steel making processes.

  20. 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.

  1. Pion-nucleon {sigma} term in lattice QCD

    SciTech Connect

    Fukugita, M.; Kuramashi, Y.; Okawa, M.; Ukawa, A.

    1995-05-01

    We calculate both the connected and disconnected contributions to the {pi}-{ital N} {sigma} term in quenched lattice QCD with the Wilson quark action on a 12{sup 3}{times}20 lattice at {beta}=5.7 with the lattice spacing {ital a}{approx}0.14 fm. The latter is evaluated with the variant wall source method, previously applied successfully for {pi}-{pi} scattering lengths and the {eta}{prime} meson mass. We found the disconnected contribution to be about twice as large as the connected one. The value for the full {pi}-{ital N} {sigma} term {sigma}=40--60 MeV is consistent with the experimental estimates. The nucleon matrix element of the strange quark density {ital {bar s}s} is fairly large in our result.

  2. An analysis of nonlinear behavior in delta-sigma modulators

    NASA Astrophysics Data System (ADS)

    Ardalan, Sasan H.; Paulos, John J.

    1987-06-01

    The paper introduces a new method of analysis for delta-sigma modulators based on modeling the nonlinear quantizer with a linearized gain, obtained by minimizing a mean-square-error criterion, followed by an additive noise source representing distortion components. In the paper, input signal amplitude dependencies of delta-sigma modulator stability and signal-to-noise ratio are analyzed. It is shown that due to the nonlinearity of the quantizer, the signal-to-noise ratio of the modulator may decrease as the input amplitude increases prior to saturation. Also, a stable third-order delta-sigma modulator may become unstable by increasing the input amplitude beyond a certain threshold. Both of these phenomena are explained by the nonlinear analysis of this paper. The analysis is carried out for both dc and sinusoidal excitations.

  3. 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.

  4. 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.

  5. Role of the alternative sigma factor sigma on Staphylococcus aureus resistance to stresses of relevance to food preservation.

    PubMed

    Cebrián, G; Sagarzazu, N; Aertsen, A; Pagán, R; Condón, S; Mañas, P

    2009-07-01

    To examine the role of the alternative general stress sigma factor sigma(B) on the resistance of Staphylococcus aureus to stresses of relevance to food preservation, with special emphasis on emerging technologies such as pulsed electric fields (PEF) and high hydrostatic pressure (HHP). S. aureus strain Newman and its isogenic DeltasigB mutant were grown to exponential and stationary growth phases and its resistance to various stresses was tested. The absence of the sigma(B) factor caused a decrease in the resistance to heat, PEF, HHP, alkali, acid and hydrogen peroxide. In the case of heat, the influence of the sigma(B) factor was particularly important, and decreases in decimal reduction time values of ninefold were observed as a result of its deficiency. The increased thermotolerance of the parental strain as compared with the sigB mutant could be attributed to a better capacity to sustain and repair sublethal damages caused by heat. sigma(B) factor provides S. aureus cells with resistance to multiple stresses, increasing survival to heat, PEF and HHP treatments. Results obtained in this work help in understanding the physiological mechanisms behind cell survival and death in food-processing environments.

  6. 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.

  7. All optical asynchronous binary delta-sigma modulator

    NASA Astrophysics Data System (ADS)

    Tafazoli, M.; Davoudzadeh, N.; Sayeh, M. R.

    2013-03-01

    We present the first all optical delta-sigma modulator using a bistable device and a leaky integrator. In this paper, a novel tri-coupled ring geometry is utilized, resulting in resonance which is a building block for delta-sigma modulator. In each ring, the main active element is a semiconductor optical amplifier (SOA). The experimental result of the implemented setup is in a good agreement with our presented theory. Applying optical discrete components leads to a sampling rate of 660 kS/s. The higher frequency can be reached easily by using faster bistable devices and shorter loops.

  8. 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

  9. Generalized Kähler Geometry from Supersymmetric Sigma Models

    NASA Astrophysics Data System (ADS)

    Bredthauer, Andreas; Lindström, Ulf; Persson, Jonas; Zabzine, Maxim

    2006-09-01

    We give a physical derivation of generalized Kähler geometry. Starting from a supersymmetric nonlinear sigma model, we rederive and explain the results of Gualtieri (Generalized complex geometry, DPhil thesis, Oxford University, 2004) regarding the equivalence between generalized Kähler geometry and the bi-hermitean geometry of Gates et al. (Nucl Phys B248:157, 1984). When cast in the language of supersymmetric sigma models, this relation maps precisely to that between the Lagrangian and the Hamiltonian formalisms. We also discuss topological twist in this context.

  10. On the Relationship Between Sigma Models and Spin Chains

    NASA Astrophysics Data System (ADS)

    Controzzi, D.; Hawkins, E.

    We consider the two-dimensional O(3) non-linear sigma model with topological term using a lattice regularization introduced by Shankar and Read [Nucl. Phys. B 336, 457 (1990)], that is suitable for studying the strong coupling regime. When this lattice model is quantized, the coefficient θ of the topological term is quantized as θ=2πs, with s integer or half-integer. We study in detail the relationship between the low energy behaviour of this theory and the one-dimensional spin-s Heisenberg model. We generalize the analysis to sigma models with other symmetries.

  11. A two-plasmid system for identification of promoters recognized by RNA polymerase containing extracytoplasmic stress response sigma(E) in Escherichia coli.

    PubMed

    Rezuchova, B; Kormanec, J

    2001-06-01

    We have previously established a two-plasmid system in Escherichia coli for identification of promoters recognized by RNA polymerase containing a heterologous sigma factor. Attempts to optimize this system for identification of promoters recognized by RNA polymerase containing E. coli extracytoplasmic stress response sigma(E) failed owing to high toxicity of the expressed rpoE. A new system for identification of sigma(E)-cognate promoters was established, and verified using the two known sigma(E)-dependent promoters, rpoEp2 and degPp. Expression of the sigma(E)-encoding rpoE gene was under the control of the AraC-dependent P(BAD) promoter. A low level of arabinose induced a non-toxic, however, sufficient level of sigma(E) to interact with the core enzyme of RNA polymerase. Such an RNA polymerase holoenzyme recognized both known sigma(E)-dependent promoters, rpoEp2 and degPp, which were cloned in the compatible promoter probe plasmid, upstream of a promoterless lacZ alpha reporter gene. This new system has proved to be useful for identification of E. coli sigma(E)-cognate promoters. Moreover, the system could be used for identification of ECF sigma-cognate promoters from other bacteria.

  12. 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

    NASA Astrophysics Data System (ADS)

    González-Lópezlira, Rosa A.; Pflamm-Altenburg, Jan; Kroupa, Pavel

    2013-06-01

    We analyze the relationship between maximum cluster mass and surface densities of total gas (Σgas), molecular gas (\\Sigma _H_2), neutral gas (\\Sigma _{H\\,\\scriptsize{I}}), and star formation rate (ΣSFR) 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_3rd \\propto \\Sigma _H\\,\\scriptsize{I}^{0.4 +/- 0.2}, whereM 3rd is the median of the five most massive clusters. There is no correlation withΣgas,ΣH2, orΣSFR. For clusters younger than 10 Myr, M_3rd \\propto \\Sigma _{H\\,\\scriptsize{I}}^{0.6 +/- 0.1} and M_3rd \\propto \\Sigma _gas^{0.5 +/- 0.2}; there is no correlation with either \\Sigma _H_2 orΣSFR. 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_3rd \\propto \\Sigma _gas^{3.8 +/- 0.3}, M_3rd \\propto \\Sigma _H_2^{1.2 +/- 0.1}, and M_3rd \\propto \\Sigma _SFR^{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 traveled too far from their birth sites, the poor resolution of the radio data compared to the physical sizes of the clusters results in measuredΣ that are likely quite

  13. REGULATION OF STAR FORMATION RATES IN MULTIPHASE GALACTIC DISKS: NUMERICAL TESTS OF THE THERMAL/DYNAMICAL EQUILIBRIUM MODEL

    SciTech Connect

    Kim, Chang-Goo; Kim, Woong-Tae; Ostriker, Eve C. E-mail: wkim@astro.snu.ac.kr

    2011-12-10

    We use vertically resolved numerical hydrodynamic simulations to study star formation and the interstellar medium (ISM) in galactic disks. We focus on outer-disk regions where diffuse H I dominates, with gas surface densities {Sigma} = 3-20 M{sub Sun} pc{sup -2} and star-plus-dark matter volume densities {rho}{sub sd} = 0.003-0.5 M{sub Sun} pc{sup -3}. Star formation occurs in very dense, self-gravitating clouds that form by mergers of smaller cold cloudlets. Turbulence, driven by momentum feedback from supernova events, destroys bound clouds and puffs up the disk vertically. Time-dependent radiative heating (FUV from recent star formation) offsets gas cooling. We use our simulations to test a new theory for self-regulated star formation. Consistent with this theory, the disks evolve to a state of vertical dynamical equilibrium and thermal equilibrium with both warm and cold phases. The range of star formation surface densities and midplane thermal pressures is {Sigma}{sub SFR} {approx} 10{sup -4} to 10{sup -2} M{sub Sun} kpc{sup -2} yr{sup -1} and P{sub th}/k{sub B} {approx} 10{sup 2} to 10{sup 4} cm{sup -3} K. In agreement with observations, turbulent velocity dispersions are {approx}7 km s{sup -1} and the ratio of the total (effective) to thermal pressure is P{sub tot}/P{sub th} {approx} 4-5, across this whole range (provided shielding is similar to the solar neighborhood). We show that {Sigma}{sub SFR} is not well correlated with {Sigma} alone, but rather with {Sigma}{radical}({rho}{sub sd}), because the vertical gravity from stars and dark matter dominates in outer disks. We also find that {Sigma}{sub SFR} has a strong, nearly linear correlation with P{sub tot}, which itself is within {approx}13% of the dynamical equilibrium estimate P{sub tot,DE}. The quantitative relationships we find between {Sigma}{sub SFR} and the turbulent and thermal pressures show that star formation is highly efficient for energy and momentum production, in contrast to the low

  14. 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.

  15. Ice Stars

    NASA Image and Video Library

    2017-09-27

    Ice Stars - August 4th, 2002 Description: Like distant galaxies amid clouds of interstellar dust, chunks of sea ice drift through graceful swirls of grease ice in the frigid waters of Foxe Basin near Baffin Island in the Canadian Arctic. Sea ice often begins as grease ice, a soupy slick of tiny ice crystals on the ocean's surface. As the temperature drops, grease ice thickens and coalesces into slabs of more solid ice. Credit: USGS/NASA/Landsat 7 To learn more about the Landsat satellite go to: landsat.gsfc.nasa.gov/ NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Join us on Facebook

  16. Voltage-gated sodium channel modulation by sigma-receptors in cardiac myocytes and heterologous systems.

    PubMed

    Johannessen, Molly; Ramachandran, Subramaniam; Riemer, Logan; Ramos-Serrano, Andrea; Ruoho, Arnold E; Jackson, Meyer B

    2009-05-01

    The sigma-receptor, a broadly distributed integral membrane protein with a novel structure, is known to modulate various voltage-gated K(+) and Ca(2+) channels through a mechanism that involves neither G proteins nor phosphorylation. The present study investigated the modulation of the heart voltage-gated Na(+) channel (Na(v)1.5) by sigma-receptors. The sigma(1)-receptor ligands [SKF-10047 and (+)-pentazocine] and sigma(1)/sigma(2)-receptor ligands (haloperidol and ditolylguanidine) all reversibly inhibited Na(v)1.5 channels to varying degrees in human embryonic kidney 293 (HEK-293) cells and COS-7 cells, but the sigma(1)-receptor ligands were less effective in COS-7 cells. The same four ligands also inhibited Na(+) current in neonatal mouse cardiac myocytes. In sigma(1)-receptor knockout myocytes, the sigma(1)-receptor-specific ligands were far less effective in modulating Na(+) current, but the sigma(1)/sigma(2)-receptor ligands modulated Na(+) channels as well as in wild type. Photolabeling with the sigma(1)-receptor photoprobe [(125)I]-iodoazidococaine demonstrated that sigma(1)-receptors were abundant in heart and HEK-293 cells, but scarce in COS-7 cells. This difference was consistent with the greater efficacy of sigma(1)-receptor-specific ligands in HEK-293 cells than in COS-7 cells. sigma-Receptors modulated Na(+) channels despite the omission of GTP and ATP from the patch pipette solution. sigma-Receptor-mediated inhibition of Na(+) current had little if any voltage dependence and produced no change in channel kinetics. Na(+) channels represent a new addition to the large number of voltage-gated ion channels modulated by sigma-receptors. The modulation of Na(v)1.5 channels by sigma-receptors in the heart suggests an important pathway by which drugs can alter cardiac excitability and rhythmicity.

  17. 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

  18. [Transfer energy disposal in collisions of NaK (6(1)sigma+) with H2].

    PubMed

    Zhu, Yong-Le; Wang, Shu-Ying; Liu, Jing; Zhong, Chong-Yu; Yolwas, A; Dai, Kang; Shen, Yi-Fan

    2014-04-01

    The radiative lifetimes and rate coefficients for deactivation of high lying 6(1)sigma+ state of NaK by collisions with H2 were studied. An OPO laser was set to a particular 2(1)sigma+ <-- 1(1)sigma+ transition. Another single mode Ti sapphire laser was then used to excite molecule from 2(1)sigma+ level to the 6(1)sigma+ state. The predissociation was monitored by the atomic potassium emission at the 3D --> 4P (1.7 microm) or the S --> 4P (1.24 microm), while bound state radiative processes were monitored by total fluorescence from the upper state to the various levels, all studied as a function of H2 density. The values for predissociation, collisional dissociation and collisional depopulation rate coefficients were obtained. The decay signal of the time resolved fluorescence from the 6(1)sigma+ --> 2(1)sigma+, 6(1)sigma+ -->1(1)sigma+ or 2(1)sigma+ --> 1(1)sigma+ transition was monitored. Based on the Stern-Volmer equation, the radiative lifetimes were monitored for 6(1)sigma+ --> 2(1)sigma+ and 2(1)sigma+ --> 1(1)sigma+ transition. The rate coefficients for deactivation of collisions with H2 were monitored for 6(1)sigma+ --> 2(1)sigma+, 6(1)sigma+ --> 1(1)sigma+ and 2(1)sigma+ -->1(1)sigma+. When the density of H2 was 10(19) cm(-3), the total collisional transfer energy (15 426 cm(-1)) and radiative energy (10 215 cm(-1)) were obtained. The relative fraction ((f(v)), (f(R)), (f(T)) of average energy disposal was derived as (0.58, 0.03, 0.39); (f(v)), (f(R)), (f(T)) represent separately the relative fraction of average energy disposal among vibration, rotation and translation. The major vibrational and translational energy release supports the assumption that the 6(1)sigma(+) -H2 collision occurs primarily in a collisional energy transfer mechanism. In this experiment, alkali molecules relative energy population ratio was determined through using the time integrated intensity, so we can get the total transfer energy. That the NaK (6(1)sigma+) energy transfers to

  19. 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.

  20. Using Six Sigma and Lean methodologies to improve OR throughput.

    PubMed

    Fairbanks, Catharine B

    2007-07-01

    Improving patient flow in the perioperative environment is challenging, but it has positive implications for both staff members and for the facility. One facility in vermont improved patient throughput by incorporating Six Sigma and Lean methodologies for patients undergoing elective procedures. The results of the project were significantly improved patient flow and increased teamwork and pride among perioperative staff members. (c) AORN, Inc, 2007.

  1. 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…

  2. 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.

  3. Multiplexed noise shaping structures for Delta-Sigma modulators

    NASA Astrophysics Data System (ADS)

    Czarnul, Z.; Yesilyurt, A. G.; Temes, G. C.

    1991-12-01

    A new structure for realizing a multiplexed noise-shaping A/D convertor is proposed. It improves the performance of first- or second-order Delta-Sigma modulators by employing additional feedback paths for suppressing the quantizer error. The structure, its theoretical analysis, and simulations confirming the improved resolution are presented.

  4. Application of Six Sigma methodology to a diagnostic imaging process.

    PubMed

    Taner, Mehmet Tolga; Sezen, Bulent; Atwat, Kamal M

    2012-01-01

    This paper aims to apply the Six Sigma methodology to improve workflow by eliminating the causes of failure in the medical imaging department of a private Turkish hospital. Implementation of the design, measure, analyse, improve and control (DMAIC) improvement cycle, workflow chart, fishbone diagrams and Pareto charts were employed, together with rigorous data collection in the department. The identification of root causes of repeat sessions and delays was followed by failure, mode and effect analysis, hazard analysis and decision tree analysis. The most frequent causes of failure were malfunction of the RIS/PACS system and improper positioning of patients. Subsequent to extensive training of professionals, the sigma level was increased from 3.5 to 4.2. The data were collected over only four months. Six Sigma's data measurement and process improvement methodology is the impetus for health care organisations to rethink their workflow and reduce malpractice. It involves measuring, recording and reporting data on a regular basis. This enables the administration to monitor workflow continuously. The improvements in the workflow under study, made by determining the failures and potential risks associated with radiologic care, will have a positive impact on society in terms of patient safety. Having eliminated repeat examinations, the risk of being exposed to more radiation was also minimised. This paper supports the need to apply Six Sigma and present an evaluation of the process in an imaging department.

  5. Application of Six Sigma methodology to a cataract surgery unit.

    PubMed

    Taner, Mehmet Tolga

    2013-01-01

    The article's aim is to focus on the application of Six Sigma to minimise intraoperative and post-operative complications rates in a Turkish public hospital cataract surgery unit. Implementing define-measure-analyse-improve and control (DMAIC) involves process mapping, fishbone diagrams and rigorous data-collection. Failure mode and effect analysis (FMEA), pareto diagrams, control charts and process capability analysis are applied to redress cataract surgery failure root causes. Inefficient skills of assistant surgeons and technicians, low quality of IOLs used, wrong IOL placement, unsystematic sterilisation of surgery rooms and devices, and the unprioritising network system are found to be the critical drivers of intraoperative-operative and post-operative complications. Sigma level was increased from 2.60 to 3.75 subsequent to extensive training of assistant surgeons, ophthalmologists and technicians, better quality IOLs, systematic sterilisation and air-filtering, and the implementation of a more sophisticated network system. This article shows that Six Sigma measurement and process improvement can become the impetus for cataract unit staff to rethink their process and reduce malpractices. Measuring, recording and reporting data regularly helps them to continuously monitor their overall process and deliver safer treatments. This is the first Six Sigma ophthalmology study in Turkey.

  6. 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…

  7. SIGMA--A Graphical Approach to Teaching Simulation.

    ERIC Educational Resources Information Center

    Schruben, Lee W.

    1992-01-01

    SIGMA (Simulation Graphical Modeling and Analysis) is a computer graphics environment for building, testing, and experimenting with discrete event simulation models on personal computers. It uses symbolic representations (computer animation) to depict the logic of large, complex discrete event systems for easier understanding and has proven itself…

  8. 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.

  9. Practical application of Sigma Metrics QC procedures in clinical chemistry.

    PubMed

    Schoenmakers, Christian H H; Naus, Andre J M; Vermeer, Henricus J; van Loon, Douwe; Steen, Gerard

    2011-11-01

    Many labs have not yet selected the most appropriate Westgard Quality Control (QC) rule for each test. This is mainly due to the apparent complexity of the matter. From the Westgard OPSpecs Charts QC planning tool and the Sigma Metrics formula's it was deduced that every Westgard rule has its own Sigma value. This was converted to an easy three-step road map to optimal Westgard QC rules. The road map provided is based on Sigma Metrics that hold a definition of "world class quality", at which no further effort to increase quality needs to be taken. Furthermore, it is shown that clinical chemical tests can be classified as "good": quality at or above world class, "bad": quality below world class but controllable with Westgard QC rules and "ugly": quality not controllable with Westgard QC rules alone. Finally, practical tips of how to deal with this and related aspects are given. The use of the road map based on Sigma Metrics leads to fast and easy implementation of optimal Westgard QC rules.

  10. Analysis of Lean Six Sigma in the Army Contracting Process

    DTIC Science & Technology

    2011-12-01

    25 c. Lean Manufacturing ...............................................................26 d. Six Sigma...training documents and instructions. c. Lean Manufacturing The basic concept behind Lean Manufacturing systems that have been practiced for many...years in Japan are waste elimination, cost reduction and employee empowerment. Lean Manufacturing focuses on identifying and eliminating non-value

  11. 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…

  12. 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…

  13. Astronaut Walter Schirra - Assisted - Sigma "7" Spacecraft - Cape

    NASA Image and Video Library

    1962-01-01

    S62-06002 (3 Oct. 1962) --- Astronaut Walter M. Schirra Jr., pilot of the Mercury-Atlas 8 (MA-8) Earth-orbital spaceflight, is assisted by backup pilot L. Gordon Cooper into his Sigma 7 spacecraft for the begining of the MA-8 mission. Photo credit: NASA

  14. 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…

  15. 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…

  16. 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…

  17. SIGMA--A Graphical Approach to Teaching Simulation.

    ERIC Educational Resources Information Center

    Schruben, Lee W.

    1992-01-01

    SIGMA (Simulation Graphical Modeling and Analysis) is a computer graphics environment for building, testing, and experimenting with discrete event simulation models on personal computers. It uses symbolic representations (computer animation) to depict the logic of large, complex discrete event systems for easier understanding and has proven itself…

  18. 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.

  19. 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…

  20. 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.

  1. 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.

  2. Single-Station Sigma for the Iranian Strong Motion Stations

    NASA Astrophysics Data System (ADS)

    Zafarani, H.; Soghrat, M. R.

    2017-07-01

    In development of ground motion prediction equations (GMPEs), the residuals are assumed to have a log-normal distribution with a zero mean and a standard deviation, designated as sigma. Sigma has significant effect on evaluation of seismic hazard for designing important infrastructures such as nuclear power plants and dams. Both aleatory and epistemic uncertainties are involved in the sigma parameter. However, ground-motion observations over long time periods are not available at specific sites and the GMPEs have been derived using observed data from multiple sites for a small number of well-recorded earthquakes. Therefore, sigma is dominantly related to the statistics of the spatial variability of ground motion instead of temporal variability at a single point (ergodic assumption). The main purpose of this study is to reduce the variability of the residuals so as to handle it as epistemic uncertainty. In this regard, it is tried to partially apply the non-ergodic assumption by removing repeatable site effects from total variability of six GMPEs driven from the local, Europe-Middle East and worldwide data. For this purpose, we used 1837 acceleration time histories from 374 shallow earthquakes with moment magnitudes ranging from M w 4.0 to 7.3 recorded at 370 stations with at least two recordings per station. According to estimated single-station sigma for the Iranian strong motion stations, the ratio of event-corrected single-station standard deviation (Φ ss) to within-event standard deviation (Φ) is about 0.75. In other words, removing the ergodic assumption on site response resulted in 25% reduction of the within-event standard deviation that reduced the total standard deviation by about 15%.

  3. Sigma factors from E. coli, B. subtilis, phage SP01, and phage T4 are homologous proteins.

    PubMed Central

    Gribskov, M; Burgess, R R

    1986-01-01

    We show, using dot matrix comparisons and statistical analysis of sequence alignments, that seven sequenced sigma factors, E. coli sigma-70 and sigma-32, B. subtilis sigma-43 and sigma-29, phage SP01 gene products 28 and 34, and phage T4 gene product 55, comprise a homologous family of proteins. Sigma-70, sigma-32, and sigma-43 each have two copies of a sequence similar to the helix-turn-helix DNA binding motif seen in CRP, and lambda repressor and cro proteins. B. subtilis sigma-29, SP01 gp28, and SP01 gp34 have at least one copy similar to this sequence. We propose that a second sequence, conserved in all seven proteins is the core RNA polymerase binding site. A third region, present only in sigma-70 and sigma-43, may also be involved in interaction with core. Available mutational evidence supports our model for sigma factor structure. PMID:3092189

  4. Role of Autoregulation and Relative Synthesis of Operon Partners in Alternative Sigma Factor Networks

    PubMed Central

    2016-01-01

    Despite the central role of alternative sigma factors in bacterial stress response and virulence their regulation remains incompletely understood. Here we investigate one of the best-studied examples of alternative sigma factors: the σB network that controls the general stress response of Bacillus subtilis to uncover widely relevant general design principles that describe the structure-function relationship of alternative sigma factor regulatory networks. We show that the relative stoichiometry of the synthesis rates of σB, its anti-sigma factor RsbW and the anti-anti-sigma factor RsbV plays a critical role in shaping the network behavior by forcing the σB network to function as an ultrasensitive negative feedback loop. We further demonstrate how this negative feedback regulation insulates alternative sigma factor activity from competition with the housekeeping sigma factor for RNA polymerase and allows multiple stress sigma factors to function simultaneously with little competitive interference. PMID:27977677

  5. 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

  6. Environmental Professional’s Guide to Lean and Six Sigma: Executive Summary

    EPA Pesticide Factsheets

    Introduction to the guide that describes how Lean and Six Sigma relate to the environment and provides guidance on how environmental professionals can connect with Lean and Six Sigma activities to generate better environmental and operational results.

  7. 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.

  8. 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.

  9. 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)

  10. 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.

  11. SEGUE: A SPECTROSCOPIC SURVEY OF 240,000 STARS WITH g = 14-20

    SciTech Connect

    Yanny, Brian; Adelman-McCarthy, Jennifer K.; Alcorn, Bonnie; Allam, Sahar; Bastian, Steve; Boroski, William N.; Rockosi, Constance; Knapp, Gillian R.; Allende Prieto, Carlos; An, Deokkeun; Anderson, Kurt S. J.; Bizyaev, Dmitry; Blythe, Norm; Anderson, Scott; Bochanski, John J.; Bailer-Jones, Coryn A. L.; Bell, Eric; Beers, Timothy C.; Belokurov, Vasily

    2009-05-15

    The Sloan Extension for Galactic Understanding and Exploration (SEGUE) Survey obtained {approx}240,000 moderate-resolution (R {approx} 1800) spectra from 3900 A to 9000 A 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.

  12. 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.

  13. Sigma ligands indirectly modulate the NMDA receptor-ion channel complex on intact neuronal cells via sigma 1 site.

    PubMed

    Yamamoto, H; Yamamoto, T; Sagi, N; Klenerová, V; Goji, K; Kawai, N; Baba, A; Takamori, E; Moroji, T

    1995-01-01

    To investigate the modulatory effects of sigma ligands on the N-methyl-D-aspartate (NMDA) receptor-ion channel complex in vivo, we examined the intact cell binding of 3H-N-[1-(2-thienyl)cyclohexyl]piperidine (3H-TCP) to cultured neuronal cells prepared from fetal rat telencephalon. The 3H-TCP binding was saturable, reversible, and inhibited by a selective NMDA receptor antagonist, D-amino-5-phosphonovaleric acid. MII-limolar Mg2+ inhibited 3H-TCP binding both in the absence and presence of L-glutamate. 5-Methyl-10,11-dihydro-5H-dibenzo [a,d]cyclohepten-5,10-imine maleate (MK801) inhibited 3H-TCP intact cell binding in a competitive manner, while haloperidol inhibited it in a noncompetitive manner. The effect of the test drugs to inhibit 3H-TCP intact cell binding was in the order of dextromethorphan, haloperidol > (+/-)MK 801 > (+)pentazocine > (-)pentazocine > DTG > PCP > (+)-N-allylnormetazocine [(+)SKF 10047] > (+)3-(3-hydroxyphenyl)-N- (1-propyl)piperidine [(+)3-PPP] > (-)SKF 10047 > (-)3-PPP. The IC50 values of the six sigma ligands for 3H-TCP binding were closely correlated with the Ki values of the corresponding drugs for DTG site 1 in the guinea pig brain reported by Rothman et al. (1991). These findings suggest that the sigma ligand indirectly modulates the NMDA receptor ion channel complex, presumably through sigma 1 sites in vivo as well as in vitro.

  14. Coronal activity in F-, G-, and K-type stars. IV - Evidence for expanding loop geometries in stellar coronae

    NASA Technical Reports Server (NTRS)

    Schrijver, C. J.; Lemen, J. R.; Mewe, R.

    1989-01-01

    A detailed analysis is presented of X-ray spectra of Capella and of Sigma2 CrB. The spectra of both stars are compatible with coronae consisting of two different ensembles of static loops with different maximum temperatures and ratios of the cross sectional areas at the loop top and at the footpoint. The cool (5 MK) loop components in both stars show evidence of relatively strong expansion with height. The hot (30 MK) components appear to expand much less.

  15. Coronal activity in F-, G-, and K-type stars. IV - Evidence for expanding loop geometries in stellar coronae

    NASA Technical Reports Server (NTRS)

    Schrijver, C. J.; Lemen, J. R.; Mewe, R.

    1989-01-01

    A detailed analysis is presented of X-ray spectra of Capella and of Sigma2 CrB. The spectra of both stars are compatible with coronae consisting of two different ensembles of static loops with different maximum temperatures and ratios of the cross sectional areas at the loop top and at the footpoint. The cool (5 MK) loop components in both stars show evidence of relatively strong expansion with height. The hot (30 MK) components appear to expand much less.

  16. Sigma-1 Receptor Agonism Promotes Mechanical Allodynia After Priming the Nociceptive System with Capsaicin.

    PubMed

    Entrena, J M; Sánchez-Fernández, C; Nieto, F R; González-Cano, R; Yeste, S; Cobos, E J; Baeyens, J M

    2016-11-25

    Sigma-1 receptor antagonists promote antinociception in several models of pain, but the effects of sigma-1 agonists on nociception (particularly when the nociceptive system is primed) are not so well characterized; therefore we evaluated the effects of sigma-1 agonists on pain under different experimental conditions. The systemic administration of the selective sigma-1 agonists (+)-pentazocine and PRE-084, as well as the nonselective sigma-1 agonist carbetapentane (used clinically as an antitussive drug), did not alter sensitivity to mechanical stimulation under baseline conditions. However, they greatly promoted secondary mechanical allodynia after priming the nociceptive system with capsaicin. These effects of sigma-1 agonists were consistent in terms potency with the affinities of these drugs for sigma-1 receptors, were reversed by sigma-1 antagonists, and were not observed in sigma-1 knockout mice, indicating that they are sigma-1-mediated. Repeated systemic treatment with PRE-084 induced proallodynic effects even 24 h after treatment completion, but only after the nociceptive system was primed. However, neither the presence of this drug in the organism nor changes in sigma-1 receptor expression in areas involved in pain processing explains its long-term effects, suggesting that sustained sigma-1 agonism induces plastic changes in the nociceptive system that promote nociception.

  17. 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.

  18. Sigma-1 Receptor Agonism Promotes Mechanical Allodynia After Priming the Nociceptive System with Capsaicin

    PubMed Central

    Entrena, J. M.; Sánchez-Fernández, C.; Nieto, F. R.; González-Cano, R.; Yeste, S.; Cobos, E. J.; Baeyens, J. M.

    2016-01-01

    Sigma-1 receptor antagonists promote antinociception in several models of pain, but the effects of sigma-1 agonists on nociception (particularly when the nociceptive system is primed) are not so well characterized; therefore we evaluated the effects of sigma-1 agonists on pain under different experimental conditions. The systemic administration of the selective sigma-1 agonists (+)-pentazocine and PRE-084, as well as the nonselective sigma-1 agonist carbetapentane (used clinically as an antitussive drug), did not alter sensitivity to mechanical stimulation under baseline conditions. However, they greatly promoted secondary mechanical allodynia after priming the nociceptive system with capsaicin. These effects of sigma-1 agonists were consistent in terms potency with the affinities of these drugs for sigma-1 receptors, were reversed by sigma-1 antagonists, and were not observed in sigma-1 knockout mice, indicating that they are sigma-1-mediated. Repeated systemic treatment with PRE-084 induced proallodynic effects even 24 h after treatment completion, but only after the nociceptive system was primed. However, neither the presence of this drug in the organism nor changes in sigma-1 receptor expression in areas involved in pain processing explains its long-term effects, suggesting that sustained sigma-1 agonism induces plastic changes in the nociceptive system that promote nociception. PMID:27886264

  19. 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…

  20. 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…

  1. Magnetic Fields in Stars

    NASA Astrophysics Data System (ADS)

    Landstreet, J.; Murdin, P.

    2000-11-01

    Magnetism—the force that deflects the needle of a compass—and magnetic fields have been found in some hundreds of stars during the past 50 yr. Magnetic fields have been detected in T Tauri stars and other pre-main-sequence stars, several types of main sequence stars, white dwarfs and neutron stars. We now know a number of methods by which such magnetic fields may be detected, we are in the proces...

  2. Up-regulation of sigma(1) receptor mRNA in rat brain by a putative atypical antipsychotic and sigma receptor ligand.

    PubMed

    Zamanillo, D; Andreu, F; Ovalle, S; Pérez, M P; Romero, G; Farré, A J; Guitart, X

    2000-03-24

    Sigma(1) (sigma(1)) receptor mRNA expression was studied in the prefrontal cortex, striatum, hippocampus and cerebellum of rat brain by northern blot and in situ hybridization. The effects of a chronic treatment with antipsychotic drugs (haloperidol and clozapine), and with E-5842, a sigma(1) receptor ligand and putative atypical antipsychotic on sigma(1) receptor expression were examined. A significant increase in the levels of sigma(1) receptor mRNA in the prefrontal cortex and striatum after E-5842 administration was observed, while no apparent changes were seen with either haloperidol or clozapine. Our results suggest a long-term adaptation of the sigma(1) receptor at the level of mRNA expression in specific areas of the brain as a response to a sustained treatment with E-5842.

  3. An evaluation of the rate of absorption of solar radiation in the O2(X3Sigma-g - b1Sigma-g) transition

    NASA Technical Reports Server (NTRS)

    Mlynczak, Martin G.

    1993-01-01

    The rate at which molecular oxygen absorbs radiation in the O2(X3Sigma-g - b1Sigma-g) transition is calculated using a line-by-line radiative transfer model. This rate is critical to the determination of the population of the O2(b1Sigma-g) state required for studies of the O2(b1Sigma-g - X3Sigma-g) dayglow, the O2(a1Delta-g - X3Sigma-g) dayglow, and possibly the rates of oxidation of H2 and N2O. Previous evaluations of this rate (which is sometimes called the g-factor) have significantly overestimated its value. The rate is tabulated as a function of altitude, pressure, and solar zenith angle.

  4. An evaluation of the rate of absorption of solar radiation in the O2(X3Sigma-g - b1Sigma-g) transition

    NASA Technical Reports Server (NTRS)

    Mlynczak, Martin G.

    1993-01-01

    The rate at which molecular oxygen absorbs radiation in the O2(X3Sigma-g - b1Sigma-g) transition is calculated using a line-by-line radiative transfer model. This rate is critical to the determination of the population of the O2(b1Sigma-g) state required for studies of the O2(b1Sigma-g - X3Sigma-g) dayglow, the O2(a1Delta-g - X3Sigma-g) dayglow, and possibly the rates of oxidation of H2 and N2O. Previous evaluations of this rate (which is sometimes called the g-factor) have significantly overestimated its value. The rate is tabulated as a function of altitude, pressure, and solar zenith angle.

  5. 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

  6. 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

  7. O stars and Wolf-Rayet stars.

    NASA Astrophysics Data System (ADS)

    Baade, D.; Conti, P. S.; Divan, L.; Garmany, C. D.; Henrichs, H. F.; Kudritzki, R. P.; Pauldrach, A.; Prévot-Burnichon, M.-L.; Puls, J.; Underhill, A. B.; Thomas, R. N.

    Contents: Perspective (R. N. Thomas).Part I. Introduction (L. Divan, M.-L. Prévot-Burnichon).1. Introducing the O and Wolf-Rayet stars.Part II. One perspective on O, Of, and Wolf-Rayet stars emphasizing winds and mass loss, with remarks on environment and evolution:2. Overview of O, Of, and Wolf-Rayet populations (P. S. Conti). 3. Intrinsic stellar parameters (P. S. Conti, D. Baade). 4. Stellar winds: (a) Introduction (P. S. Conti). (b) Mass loss from O stars (C. D. Garmany). (c) Mass loss in Wolf-Rayetstars (P. S. Conti). (d) Radiation-driven winds of hot luminous stars (R. P. Kudritzki, A. Pauldrach, J. Puls). (e) Intrinsic variability in ultraviolet spectra of early-type stars: the discrete absorption lines (H. Henrichs). 5. Environments and evolution (P. S. Conti).Part III. Another perspective on O, Of, and Wolf-Rayet stars, emphasizing model atmospheres and possibilities for atmospheric heating (A. B. Underhill): 6. Understanding the O and Wolf-Rayet stars. 7. Model Atmospheres and the theoryof spectra for O and Wolf-Rayet stars. 8. The physics of the mantles of hot stars. 9. Summary of processes influencing the spectra of O andWolf-Rayet stars.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. Vacuum Properties of the {Sigma}(1385){sup +} Resonance

    SciTech Connect

    Epple, E.

    2011-10-21

    We present data taken employing a proton beam incident on a liquid hydrogen target with a kinetic energy of 3.5 GeV. A total statistics of {approx_equal} 1.2.10{sup 9} events was collected by the High Acceptance Di-Electron Spectrometer (HADES) and analysed to study the properties of the {Sigma}(1385){sup +}-resonance. A clear signal corresponding to a peak of the Breit-Wigner parametrization of M = 1382.98{+-}0.79MeV/c{sup 2} and a width of {Gamma}{sub 0} = 38.78{+-}2.03 MeV/c{sup 2} was extracted. The investigation of the differential production cross- section shows a strong anisotropy in the angular distribution of the {Sigma}(1385){sup +}-hyperon with respect to the beam direction in p+p collisions.

  13. 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.

  14. Adaptive Delta-Sigma Modulation for Enhanced Input Dynamic Range

    NASA Astrophysics Data System (ADS)

    Zierhofer, Clemens M.

    2006-12-01

    An adaptive delta-sigma modulator of 1st order with one-bit quantization is presented. Adaptation is instantaneous and based on an exponential law. The feedback signal is a multibit discrete-level signal generated by a digital-to-analog converter (DAC). Compared to a nonadaptive delta-sigma modulator of 1st order, the input dynamic range is significantly enhanced. The gain in dynamic range is 6 dB per bit defining the feedback amplitude. The influence of nonideal DAC performance is discussed. It is demonstrated that an implementation of the system is realistic with standard CMOS technology. To relax the requirements to the one-bit quantizer, the quantizer input signal is amplified adaptively (Q-Switching).

  15. 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

  16. Generalized complex geometry, generalized branes and the Hitchin sigma model

    NASA Astrophysics Data System (ADS)

    Zucchini, Roberto

    2005-03-01

    Hitchin's generalized complex geometry has been shown to be relevant in compactifications of superstring theory with fluxes and is expected to lead to a deeper understanding of mirror symmetry. Gualtieri's notion of generalized complex submanifold seems to be a natural candidate for the description of branes in this context. Recently, we introduced a Batalin-Vilkovisky field theoretic realization of generalized complex geometry, the Hitchin sigma model, extending the well known Poisson sigma model. In this paper, exploiting Gualtieri's formalism, we incorporate branes into the model. A detailed study of the boundary conditions obeyed by the world sheet fields is provided. Finally, it is found that, when branes are present, the classical Batalin-Vilkovisky cohomology contains an extra sector that is related non trivially to a novel cohomology associated with the branes as generalized complex submanifolds.

  17. 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.

  18. New observations with the gamma ray imager SIGMA

    NASA Technical Reports Server (NTRS)

    Roques, J. P.; Vedrenne, G.

    1992-01-01

    Results from the use of the gamma ray telescope SIGMA are given. An identification and an extensive study was done of sources contributing to the emission of the Galactic center region above 30 keV. A strong line was observed at 480 keV from Nova Muscae, which may be interpreted as an annihilation line with a redshift due to the presence of a compact object. The soft x-ray tails observed by SIGMA in some transient sources already identified as soft x-ray transients might be a common characteristic of these objects and has to be explained. The unusual spectrum of NGC4151 with a break around 50 keV can characterize a particular state of this kind of object. If it is the case, it has interesting implications for the origin of the Cosmic Diffuse Background.

  19. Optimization of steel bar manufacturing process using six sigma

    NASA Astrophysics Data System (ADS)

    Naeem, Khawar; Ullah, Misbah; Tariq, Adnan; Maqsood, Shahid; Akhtar, Rehman; Nawaz, Rashid; Hussain, Iftikhar

    2016-03-01

    Optimization of a manufacturing process results in higher productivity and reduced wastes. Production parameters of a local steel bar manufacturing industry of Pakistan is optimized by using six Sigma-Define, measure, analyze, improve, and controlmethodology. Production data is collected and analyzed. After analysis, experimental design result is used to identify significant factors affecting process performance. The significant factors are controlled to optimized level using two-level factorial design method. A regression model is developed that helps in the estimation of response under multi variable input values. Model is tested, verified, and validated by using industrial data collected at a local steel bar manufacturing industry of Peshawar(Khyber Pakhtunkhwa, Pakistan). The sigma level of the manufacturing process is improved to 4.01 from 3.58. The novelty of the research is the identification of the significant factors along with the optimum levels that affects the process yield, and the methodology to optimize the steel bar manufacturing process.

  20. Rethinking behavioral health processes by using design for six sigma.

    PubMed

    Lucas, Anthony G; Primus, Kelly; Kovach, Jamison V; Fredendall, Lawrence D

    2015-02-01

    Clinical evidence-based practices are strongly encouraged and commonly utilized in the behavioral health community. However, evidence-based practices that are related to quality improvement processes, such as Design for Six Sigma, are often not used in behavioral health care. This column describes the unique partnership formed between a behavioral health care provider in the greater Pittsburgh area, a nonprofit oversight and monitoring agency for behavioral health services, and academic researchers. The authors detail how the partnership used the multistep process outlined in Design for Six Sigma to completely redesign the provider's intake process. Implementation of the redesigned process increased access to care, decreased bad debt and uncollected funds, and improved cash flow--while consumer satisfaction remained high.

  1. Scalar mesons in three-flavor linear sigma models

    SciTech Connect

    Deirdre Black; Amir H. Fariborz; Sherif Moussa; Salah Nasri; Joseph Schrechter

    2001-09-01

    The three flavor linear sigma model is studied in order to understand the role of possible light scalar mesons in the pi-pi, pi-K and pi-eta elastic scattering channels. The K-matrix prescription is used to unitarize tree-level amplitudes and, with a sufficiently general model, we obtain reasonable ts 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 upon how our results t in with the scalar meson puzzle. The latter involves a preliminary investigation of possible mixing between scalar nonets.

  2. Signaling Mechanisms for Activation of Extracytoplasmic Function (ECF) Sigma Factors

    PubMed Central

    Brooks, Benjamin E.; Buchanan, Susan K.

    2008-01-01

    Summary A variety of mechanisms are used to signal extracytoplasmic conditions to the cytoplasm. These mechanisms activate extracytoplasmic function (ECF) sigma factors which recruit RNA-polymerase to specific genes in order to express appropriate proteins in response to the changing environment. The two best understood ECF signaling pathways regulate σE-mediated expression of periplasmic stress response genes in Escherichia coli and FecI-mediated expression of iron-citrate transport genes in E. coli. Homologues from other Gram-negative bacteria suggest that these two signaling mechanisms and variations on these mechanisms may be the general schemes by which ECF sigma factors are regulated in Gram-negative bacteria. PMID:17673165

  3. Sigma-1 Receptor Modulates Neuroinflammation After Traumatic Brain Injury.

    PubMed

    Dong, Hui; Ma, Yunfu; Ren, Zengxi; Xu, Bin; Zhang, Yunhe; Chen, Jing; Yang, Bo

    2016-07-01

    Traumatic brain injury (TBI) remains a significant clinical problem and contributes to one-third of all injury-related deaths. Activated microglia-mediated inflammatory response is a distinct characteristic underlying pathophysiology of TBI. Here, we evaluated the effect and possible mechanisms of the selective Sigma-1 receptor agonist 2-(4-morpholinethyl)-1-phenylcyclohexanecarboxylate (PRE-084) in mice TBI model. A single intraperitoneal injection 10 μg/g PRE-084, given 15 min after TBI significantly reduced lesion volume, lessened brain edema, attenuated modified neurological severity score, increased the latency time in wire hang test, and accelerated body weight recovery. Moreover, immunohistochemical analysis with Iba1 staining showed that PRE-084 lessened microglia activation. Meanwhile, PRE-084 reduced nitrosative and oxidative stress to proteins. Thus, Sigma-1 receptors play a major role in inflammatory response after TBI and may serve as useful target for TBI treatment in the future.

  4. Creativity, innovation and lean sigma: a controversial combination?

    PubMed

    Johnstone, Craig; Pairaudeau, Garry; Pettersson, Jonas A

    2011-01-01

    The application of lean sigma is gaining momentum in drug discovery and development but it remains controversial because of perceptions that process improvement will suppress much-needed creativity and innovation. We review the conditions required to support creativity and innovation and the principles and benefits of lean sigma in a drug discovery environment. We conclude that it is desirable to create a unified climate that encourages and enables both innovation and continuous improvement and that this is possible if three key tensions are handled carefully and with due respect to the needs of research. These three potential traps occur in the interpretation of standardization, the role of variation and the choice of how to use liberated capacity. Copyright © 2010 Elsevier Ltd. All rights reserved.

  5. CP 1 | 1 nonlinear sigma model vs strong electron correlations

    NASA Astrophysics Data System (ADS)

    Kochetov, E. A.; Ferraz, A.

    2017-06-01

    The nonlinear sigma model targeted on the coset supermanifold CP 1 | 1 = SU(2 | 1) / U(1 | 1) is derived in an attempt to describe the quasiclassical low-energy effective action for the doped t - J model at the SUSY point, J = 2 t. In spite of the fact that the supermanifold CP 1 | 1 indeed appears as the phase space of the strongly correlated electrons, the canonical CP 1 | 1 nonlinear sigma model (NLSM) is unable to capture the physics of strong correlations displayed by the SUSY t - J model at any finite doping. This is due to the fact that, in this regime, the doping itself cannot be self-consistently incorporated into the CP 1 | 1 NLSM.

  6. Observation of the sigma_b baryons at CDF

    SciTech Connect

    Pursley, Jennifer M.; /Johns Hopkins U.

    2007-03-01

    We present a measurement of four new bottom baryons in proton-antiproton collisions with a center of mass energy of 1.96 TeV. Using 1.1 fb{sup -1} of data collected by the CDF II detector, we observe four {Lambda}{sup 0}{sub b}{pi}{+-} resonances in the fully reconstructed decay mode {Lambda}{sup 0}{sub b} {yields} {Lambda}{sup +}{sub c}{pi}{sup -}, where {Lambda}{sup +}{sub c} {yields} pK{sup -}{pi}{sup +}. The probability for the background to produce a similar or larger signal is less than 8.3 x 10{sup -8}, corresponding to a significance of greater than 5.2 {sigma}. We interpret these baryons as the {Sigma}{sub b}{sup (*){+-}} baryons.

  7. Digital pixel sensor array with logarithmic delta-sigma architecture.

    PubMed

    Mahmoodi, Alireza; Li, Jing; Joseph, Dileepan

    2013-08-16

    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.

  8. Deformed neutron stars due to strong magnetic field in terms of relativistic mean field theories

    NASA Astrophysics Data System (ADS)

    Yanase, Kota; Yoshinaga, Naotaka

    2014-09-01

    Some observations suggest that magnetic field intensity of neutron stars that have particularly strong magnetic field, magnetars, reaches values up to 1014-15G. It is expected that there exists more strong magnetic field of several orders of magnitude in the interior of such stars. Neutron star matter is so affected by magnetic fields caused by intrinsic magnetic moments and electric charges of baryons that masses of neutron stars calculated by using Tolman-Oppenheimer-Volkoff equation is therefore modified. We calculate equation of state (EOS) in density-dependent magnetic field by using sigma-omega-rho model that can reproduce properties of stable nuclear matter in laboratory Furthermore we calculate modified masses of deformed neutron stars.

  9. The nature of the [20.0] 1Sigma+ electronic state of RhB: a multiconfigurational study.

    PubMed

    Gobbo, João Paulo; Borin, Antonio Carlos

    2007-01-07

    Multiconfigurational second order perturbation theory, with extended atomic basis sets and inclusion of scalar relativistic effects, was employed to investigate the low-lying (1)Sigma(+) electronic states of RhB. The [20.0] (1)Sigma(+) state is represented by a single configuration, mid R:[ellipsis (horizontal)]10sigma(2)11sigma(1)5pi(4)2delta(4)12sigma(1), derived from a single excitation (11sigma-->12sigma) from the ground state, which defines its electronic nature. A new excited state, coined as [9.0] (1)Delta (R(0)=1.786A, DeltaG(12)=792 cm(-1)), located 9221 cm(-1) above the X(1)Sigma(+) state, and described by the |...10sigma(2)11sigma(2)5pi(4)2delta(3)12sigma(1)> electronic configuration, was also identified.

  10. 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.

  11. Sigma Delta Signal Processing on Via-Configurable Arrays

    DTIC Science & Technology

    2016-03-31

    effective approach for developing circuits like Ms and provide application examples using these techniques. Keywords: Field Programmable Analog Array...Mask Programmable Analog Array; Mixed-Signal ASIC; Sigma Delta Modulation; Structured Array; Switched Capacitor Circuits ; Via-Configurable Array...connects the required analog and digital cells to implement a mixed-signal circuit . Unlike FPGAs, VCAs contain analog cells allowing for integration of

  12. Identification of sigma and chi phases in duplex stainless steels

    SciTech Connect

    Llorca-Isern, Núria; López-Luque, Héctor; López-Jiménez, Isabel; Biezma, Maria Victoria

    2016-02-15

    The aim of this work is to find out the most suitable method for detecting and analyzing accurately the formation conditions of secondary phases, particularly Sigma-phase (σ-phase) and Chi-phase (χ-phase) in duplex stainless steels (UNS S32205 and UNS S32750). The microstructure was characterized after a solution annealing at 1080 °C followed by an isothermal heating at 830 °C for different time ranges, ranging from 1 min to 9 h, in order to enlighten the controversial point concerning the mechanism of χ-phase nucleation in relation with the σ-phase. Etched samples were observed using optical microscopy (MO), and scanning electron microscopy (FESEM) with a backscattered electron detector (BSE) was used on unetched samples. Compositional microanalysis (EDS) was carried out for identifying the different phases present in the steels. Sigma phase was easily observed using different etching procedures, whereas χ-phase was only clearly detected with FESEM–BSE on unetched samples. The compositional analyses showed that the molybdenum content in χ-phase almost doubles the content of this element in σ-phase, and as a result the kinetics of nucleation and growth were also found to be remarkably faster when the alloy content in the steel is higher. In addition, chromium nitrides and carbides were also observed to precipitate as a result of the heat treatments and, in the case of the chromium nitrides, they act as a favorable site for the nucleation of σ-phase and χ-phase. - Highlights: • Microscopy was used on heat treated duplex steels for microstructure identification. • FESEM–BSE observation on unetched samples provided the best contrast between phases. • Analyses of carbides, nitrides, chi and sigma phases were possible by EDS and WDS. • Chromium nitrides act as favorable site for the nucleation of chi and sigma phases. • Secondary phases nucleation kinetics are faster in superduplex than in duplex steels.

  13. 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).

  14. 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.

  15. Six Sigma and modifications to gain an efficient practice.

    PubMed

    Dahl, Owen J

    2008-01-01

    Practices are inefficient in many areas of processing. Industry has an approach--Six Sigma--that works well. However, this process in its truest approach is not practical to implement in a medical practice. However, the philosophy of continuous improvement and developing an approach in any size medical practice can and will result in improvements. These improve ments will allow staff to focus on more important issues as well as improve the bottom line and cash flow.

  16. Comparing Poisson Sigma Model with A-model

    NASA Astrophysics Data System (ADS)

    Bonechi, F.; Cattaneo, A. S.; Iraso, R.

    2016-10-01

    We discuss the A-model as a gauge fixing of the Poisson Sigma Model with target a symplectic structure. We complete the discussion in [4], where a gauge fixing defined by a compatible complex structure was introduced, by showing how to recover the A-model hierarchy of observables in terms of the AKSZ observables. Moreover, we discuss the off-shell supersymmetry of the A-model as a residual BV symmetry of the gauge fixed PSM action.

  17. Integrating CMMI and Six Sigma in Software and Systems Engineering

    DTIC Science & Technology

    2005-09-01

    Carnegie Mellon University page 82 CarnegieMellon S oftware Engineer ing Inst itute Lean : Terms & Usage Kaizen - Make people’s jobs easier by taking them...oftware Engineer ing Inst itute Lean : Kaizen Procedure Top Mgmt Kick-off of event Determine Team Objectives and Goals Lean /Six Sigma Training Map as...University page 31 CarnegieMellon S oftware Engineer ing Inst itute LMC M&DS Training & Implementation 1 Executive Lean Training • Top Executives - one week

  18. Multiharmonic tracking using sigma-point Kalman filter.

    PubMed

    Kim, Sunghan; Paul, Anindya S; Wan, Eric A; McNames, James

    2008-01-01

    Several groups have proposed the state-space approach to track time-varying frequencies ofmulti-harmonic quasi-periodic signals contaminated with white Gaussian noise. We compared the extended Kalman filter (EKF) and sigma-point Kalman filter (SPKF) algorithms on this problem. On average, the SPKF outperformed the EKF and more accurately tracked the instantaneous frequency over a wide range of signal-to-noise (SNR) ratios.

  19. 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.

  20. A symmetric approach to the massive nonlinear sigma model

    DOE PAGES

    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.

  1. A Measurement & Analysis Training Solution Supporting CMMI & Six Sigma Transition

    DTIC Science & Technology

    2004-10-01

    Indicator templates added as a domain -specific tool to the Six Sigma toolkit *See Addenda for list of CMMI Process Areas © 2004 by Carnegie Mellon...Operationally Critical Threat, Asset, and Vulnerability Evaluation; Personal Software Process ; PSP; SCAMPI; SCAMPI Lead Assessor; SCAMPI...Lead Appraiser; SCE; SEI; SEPG; Team Software Process ; and TSP are service marks of Carnegie Mellon University. © 2004 by Carnegie Mellon University

  2. 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.

  3. Electromagnetic axial anomaly in a generalized linear sigma model

    NASA Astrophysics Data System (ADS)

    Fariborz, Amir H.; Jora, Renata

    2017-06-01

    We construct the electromagnetic anomaly effective term for a generalized linear sigma model with two chiral nonets, one with a quark-antiquark structure, the other one with a four-quark content. We compute in the leading order of this framework the decays into two photons of six pseudoscalars: π0(137 ), π0(1300 ), η (547 ), η (958 ), η (1295 ) and η (1760 ). Our results agree well with the available experimental data.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Resolving the Critical Ambiguities of the M-Sigma Relation

    NASA Astrophysics Data System (ADS)

    Batcheldor, Daniel

    2006-07-01

    Determining the best estimates of the masses of supermassive black holes {SMBHs} and their uncertainties is crucial for constraining the slope and scatter of the SMBH mass vs. stellar velocity dispersion {M-sigma} relation and for understanding the relation between SMBHs and their host galaxies. We propose to critically evaluate the values of the SMBH masses in a sample of 23 galaxies using data derived from STIS long-slit spectroscopy. This study will directly achieve three significant and fundamental improvements to the M-sigma relation. First, we will use all suitable STIS long-slit data to analyze SMBH masses in an entirely homogeneous fashion. Second, we will substantially increase the SMBH sample size with new estimates. Finally, we will use our state-of-the-art Schwarzschild code, which will, for the first time and independently of the modelling parameters, explore the full range of SMBH masses that give statistically acceptable fits to a given data set. These analyses can be carried out with unrivaled efficiency using the cutting-edge computing facilities available at RIT. This work will result in the most accurate and reliable estimate of the form {slope and scatter} of the M-sigma relation; to date improvements have only been somewhat incremental. Such a study will place important constraints on some of the most fundamental problems remaining in contemporary astrophysics.

  10. Evidence that sigma factors are components of chloroplast RNA polymerase.

    PubMed Central

    Troxler, R F; Zhang, F; Hu, J; Bogorad, L

    1994-01-01

    Plastid genes are transcribed by DNA-dependent RNA polymerase(s), which have been incompletely characterized and have been examined in a limited number of species. Plastid genomes contain rpoA, rpoB, rpoC1, and rpoC2 coding for alpha, beta, beta', and beta" RNA polymerase subunits that are homologous to the alpha, beta, and beta' subunits that constitute the core moiety of RNA polymerase in bacteria. However, genes with homology to sigma subunits in bacteria have not been found in plastid genomes. An antibody directed against the principal sigma subunit of RNA polymerase from the cyanobacterium Anabaena sp. PCC 7120 was used to probe western blots of purified chloroplast RNA polymerase from maize, rice, Chlamydomonas reinhardtii, and Cyanidium caldarium. Chloroplast RNA polymerase from maize and rice contained an immunoreactive 64-kD protein. Chloroplast RNA polymerase from C. reinhardtii contained immunoreactive 100- and 82-kD proteins, and chloroplast RNA polymerase from C. caldarium contained an immunoreactive 32-kD protein. The elution profile of enzyme activity of both algal chloroplast RNA polymerases coeluted from DEAE with the respective immunoreactive proteins, indicating that they are components of the enzyme. These results provide immunological evidence for sigma-like factors in chloroplast RNA polymerase in higher plants and algae. PMID:8159791

  11. Measuring neutron-star ellipticity with measurements of the stochastic gravitational-wave background

    NASA Astrophysics Data System (ADS)

    Talukder, Dipongkar; Thrane, Eric; Bose, Sukanta; Regimbau, Tania

    2014-06-01

    Galactic neutron stars are a promising source of gravitational waves in the analysis band of detectors such as Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo. Previous searches for gravitational waves from neutron stars have focused on the detection of individual neutron stars, which are either nearby or highly nonspherical. Here, we consider the stochastic gravitational-wave signal arising from the ensemble of Galactic neutron stars. Using a population synthesis model, we estimate the single-sigma sensitivity of current and planned gravitational-wave observatories to average neutron star ellipticity ɛ as a function of the number of in-band Galactic neutron stars Ntot. For the plausible case of Ntot≈53000, and assuming one year of observation time with colocated initial LIGO detectors, we find it to be σɛ=2.1×10-7, which is comparable to current bounds on some nearby neutron stars. (The current best 95% upper limits are ɛ ≲7×10-8.) It is unclear if Advanced LIGO can significantly improve on this sensitivity using spatially separated detectors. For the proposed Einstein Telescope, we estimate that σɛ=5.6×10-10. Finally, we show that stochastic measurements can be combined with measurements of individual neutron stars in order to estimate the number of in-band Galactic neutron stars. In this way, measurements of stochastic gravitational waves provide a complementary tool for studying Galactic neutron stars.

  12. Cloning, sequencing, and disruption of the Bacillus subtilis sigma 28 gene.

    PubMed Central

    Helmann, J D; Márquez, L M; Chamberlin, M J

    1988-01-01

    Bacillus subtilis contains multiple forms of RNA polymerase holoenzyme, distinguished by the presence of different specificity determinants known as sigma factors. The sigma 28 factor was initially purified as a unique transcriptional activity in vegetatively growing B. subtilis cells. Purification of the sigma 28 protein has allowed tryptic peptides to be prepared and sequenced. The sequence of one tryptic peptide fragment was used to prepare an oligonucleotide probe specific for the sigma 28 structural gene, and the gene was isolated from a B. subtilis subgenomic library. The complete nucleotide sequence of the sigma 28 gene was determined, and the cloned sigma 28 gene was used to construct a mutant strain which does not express the sigma 28 protein. This strain also failed to synthesize flagellin protein and grew as long filaments. The predicted sigma 28 gene product is a 254-amino-acid polypeptide with a calculated molecular weight of 29,500. The sigma 28 protein sequence was similar to that of other sequenced sigma factors and to the flbB gene product of Escherichia coli. Since the flbB gene product is a positive regulator of flagellar synthesis in E. coli, it is likely that sigma 28 functions to regulate flagellar synthesis in B. subtilis. Images PMID:2832368

  13. Sigma receptor ligands: possible application as therapeutic drugs and as radiopharmaceuticals.

    PubMed

    Hashimoto, Kenji; Ishiwata, Kiichi

    2006-01-01

    Sigma receptors are classified into sigma(1) and sigma(2) subtypes. These subtypes display a different tissue distribution and a distinct physiological and pharmacological profile in the central and peripheral nervous system. The characterization of these subtypes and the discovery of new specific sigma receptor ligands demonstrated that sigma receptors are novel targets for the therapeutic treatment of neuropsychiatric diseases (schizophrenia, depression, and cognition), brain ischemia, and cocaine addiction. Furthermore, imaging of sigma(1) receptors in the human brain using specific PET radioligands has started. In addition, the two sigma receptor subtypes are also expressed on tumor cells, where they could be of prognostic relevance. The ability of sigma(2) receptor agonists to inhibit tumor cell proliferation through mechanisms that might involve apoptosis, intracellular Ca(2+), and sphingolipids has promoted the development of sigma(2) receptor agonists as novel therapeutic drugs for treating cancer. Consequently, sigma(2) receptor ligands have been demonstrated to be potentially useful tumor imaging ligands. In this article, we focus on the sigma receptor ligands as therapeutic agents and as radiopharmaceuticals.

  14. A perspective on the new mechanism of antidepressants: neuritogenesis through sigma-1 receptors.

    PubMed

    Takebayashi, M; Hayashi, T; Su, T-P

    2004-11-01

    Sigma receptors were first described as one of the opiate receptor subtypes. Now it is well established that sigma receptors, existing as subtypes sigma-1 and sigma-2, are unique non-opioid receptors which are implicated in higher-ordered brain functions. Sigma-1 receptors have high to moderate affinities for (+)benzomorphans and also many psychotrophic drugs and neurosteroids. Sigma-1 receptor agonists and certain neurosteroids such as dehydroepiandrosterone sulfate (DHEA-S) have antidepressant-like effects in animal behavioral models of depression. The antidepressant-like effect induced by sigma-1 receptor agonists may involve intracellular Ca (2+) mobilization such that sigma-1 receptor agonists modulate Ca (2+) release from endoplasmic reticulum (ER) in a cytoskeletal protein-dependent manner. In addition, growth factor-induced neurite outgrowth is mediated through sigma-1 receptors, suggesting a role of antidepressants in neuroplasticity. Igmesine (JO1783), OPC-14 523 and SA4503, have recently been developed as sigma-1 agonists and are found to have antidepressant-like activity perhaps with fewer side effects. This article reviews the new potential use of sigma-1 receptor ligands in the treatment of mood disorder.

  15. CCD star trackers

    NASA Technical Reports Server (NTRS)

    Goss, W. C.

    1975-01-01

    The application of CCDs to star trackers and star mappers is considered. Advantages and disadvantages of silicon CCD star trackers are compared with those of image dissector star trackers. It is concluded that the CCD has adequate sensitivity for most single star tracking tasks and is distinctly superior in multiple star tracking or mapping applications. The signal and noise figures of several current CCD configurations are discussed. The basic structure of the required signal processing is described, and it is shown that resolution in excess of the number of CCD elements may be had by interpolation.

  16. 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.

  17. IMAGE ANALYSIS FOR COSMOLOGY: RESULTS FROM THE GREAT10 STAR CHALLENGE

    SciTech Connect

    Kitching, T. D.; Heymans, C.; Rowe, B.; Witherick, D.; Gill, M.; Massey, R.; Courbin, F.; Gentile, M.; Meylan, G.; Georgatzis, K.; Gruen, D.; Kilbinger, M.; Li, G. L.; Mariglis, A. P.; Storkey, A.; Xin, B.

    2013-04-01

    We present the results from the first public blind point-spread function (PSF) reconstruction challenge, the GRavitational lEnsing Accuracy Testing 2010 (GREAT10) Star Challenge. Reconstruction of a spatially varying PSF, sparsely sampled by stars, at non-star positions is a critical part in the image analysis for weak lensing where inaccuracies in the modeled ellipticity e and size R {sup 2} can impact the ability to measure the shapes of galaxies. This is of importance because weak lensing is a particularly sensitive probe of dark energy and can be used to map the mass distribution of large scale structure. Participants in the challenge were presented with 27,500 stars over 1300 images subdivided into 26 sets, where in each set a category change was made in the type or spatial variation of the PSF. Thirty submissions were made by nine teams. The best methods reconstructed the PSF with an accuracy of {sigma}(e) Almost-Equal-To 2.5 Multiplication-Sign 10{sup -4} and {sigma}(R {sup 2})/R {sup 2} Almost-Equal-To 7.4 Multiplication-Sign 10{sup -4}. For a fixed pixel scale, narrower PSFs were found to be more difficult to model than larger PSFs, and the PSF reconstruction was severely degraded with the inclusion of an atmospheric turbulence model (although this result is likely to be a strong function of the amplitude of the turbulence power spectrum).

  18. 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.

  19. IL-10 mediates sigma 1 receptor-dependent suppression of antitumor immunity.

    PubMed

    Zhu, Li X; Sharma, Sherven; Gardner, Brian; Escuadro, Brian; Atianzar, Kimberly; Tashkin, Donald P; Dubinett, Steven M

    2003-04-01

    Sigma receptors are unique endoplasmic reticulum proteins that mediate signaling for a variety of drugs. We determined the effect of sigma(1) receptor agonists on immune responses in a syngeneic lung cancer model. Sigma(1) receptor agonists, including cocaine, up-regulated splenocyte IL-10 mRNA and protein production in vitro in a sigma receptor-dependent, pertussis toxin-sensitive manner. In vivo, sigma(1) receptor agonists promoted tumor growth and induced IL-10 at the tumor site. Increased tumor growth was prevented by administration of specific Abs to IL-10 or by administration of specific sigma(1) receptor antagonists. We report that sigma(1) receptor ligands, including cocaine, augment tumor growth through an IL-10 dependent mechanism.

  20. 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.

  1. The Hallucinogen N,N-Dimethyltryptamine (DMT) Is an Endogenous Sigma-1 Receptor Regulator

    PubMed Central

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

    2010-01-01

    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. PMID:19213917

  2. 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.

  3. 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

  4. Sigma-1 receptors (sigma(1) binding sites) form raft-like microdomains and target lipid droplets on the endoplasmic reticulum: roles in endoplasmic reticulum lipid compartmentalization and export.

    PubMed

    Hayashi, Teruo; Su, Tsung-Ping

    2003-08-01

    The brain sigma-1 receptors can bind neurosteroids and psychotropic drugs, including neuroleptics and cocaine and are implicated in schizophrenia, depression, and drug dependence. In this study, we found that sigma-1 receptors specifically target lipid storage sites (lipid droplets) on the endoplasmic reticulum by forming a distinct class of lipid microdomains. Both endogenously expressing sigma-1 receptors and transfected C-terminally enhanced yellow fluorescent protein (EYFP)-tagged sigma-1 receptors (Sig-1R-EYFP) target unique "ring-like" structures associated with endoplasmic reticulum reticular networks in NG108-15 cells. The ring-like structures contain neutral lipids and are enlarged by the oleate treatment, indicating that they are endoplasmic reticulum-associated lipid droplets (ER-LDs). sigma-1 receptors colocalize with caveolin-2, a cholesterol-binding protein in lipid rafts on the ER-LDs, but not with adipocyte differentiation-related protein (ADRP), a cytosolic lipid droplet (c-LD)-specific protein. When the double-arginine ER retention signal on the N terminus of sigma-1 receptors is truncated, sigma-1 receptors no longer exist on ER-LDs, but predominantly target c-LDs, which contain ADRP. sigma-1 receptors on ER-LDs form detergent-resistant raft-like lipid microdomains, the buoyancy of which is different from that of plasma membrane lipid rafts. (+)-Pentazocine causes sigma-1 receptors to disappear from the microdomains. N-Terminally EYFP-tagged sigma-1 receptors (EYFP-Sig-1R) failed to target ER-LDs. EYFP-Sig-1R-transfected cells showed an unrestricted distribution of neutral lipids all over the endoplasmic reticulum network, decreases in c-LDs and cholesterol in plasma membranes, and the bulbous aggregation of endoplasmic reticulum. Thus, sigma-1 receptors are unique endoplasmic reticulum proteins that regulate the compartmentalization of lipids on the endoplasmic reticulum and their export from the endoplasmic reticulum to plasma membrane and c-LDs.

  5. Comparison of binding parameters of sigma 1 and sigma 2 binding sites in rat and guinea pig brain membranes: novel subtype-selective trishomocubanes.

    PubMed

    Nguyen, V H; Kassiou, M; Johnston, G A; Christie, M J

    1996-09-12

    Comparisons of binding parameters of [3H](+)-pentazocine and [3H]1,3-di-o-tolylguanidine (DTG) at sigma binding sites in guinea pig and rat brain membranes demonstrated that [3H](+)-pentazocine binds to a single high-affinity site, whereas [3H]DTG binds to two high-affinity sites in both species. The Kd values of the radioligands were similar in both types of membranes. However, the density of sigma 1 sites in guinea pig was significantly higher than that of rat. Novel trishomocubanes were tested for their affinities at sigma 1 and sigma 2 binding sites in guinea pig brain membranes using [3H](+)-pentazocine and [3H]DTG as the radioligands. N-(4-Phenylbutyl)-3-hydroxy-4- azahexacyclo[5.4.1.0(2,6).0(3,10).0(5,9).0(8,11)]dodecane (ANSTO-14) showed the highest affinity for the sigma 1 site (Ki = 9.4 nM) and 19-fold sigma 1/sigma 2 selectivity, as a result of increasing the alkyl chain between the cubane moiety and the aromatic ring. N-(3'-Fluorophenyl)methyl- 3-hydroxy-4-azahexacyclo[5.4.1.0(2,6).0(3,10).0(5,9).0(8,11]dodeca ne (ANSTO-19), displayed the highest affinity for sigma 2 sites (Ki = 19.6 nM) and 8-fold sigma 2/sigma 1 selectivity due to a fluoro substitution in the meta position of the aromatic ring. These represent structurally novel lead compounds, especially for the development of selective sigma 2 receptor ligands.

  6. NaK 2 (1)Sigma(+) yields 1 (1)Sigma(+) band optically pumped laser near 1. 02 micrometers

    SciTech Connect

    Clark, B.K.; Luh, W.T.; Huennekens, J.

    1989-01-01

    Optically pumped laser emission has been observed on the NaK 2(A) 1 Sigma (+) to 1 (X) 1 Sigma (+) electronic state transition. The emission occurs between 1.015 and 1.035 microns when a sodium-potassium heat-pipe oven is pumped with 695-745nm pulsed dye laser radiation. The laser emission occurs on many ro-vibrational transitions without the use of cavity mirrors. However, the addition of a simple cavity increases both the number of observed lasing transitions and the amplitude of the emission on each line. Reported are results for the dependence of the emission intensity on pump laser power, oven temperature, and buffer gas pressure.

  7. A shock-tube measurement of the SiO/E 1 Sigma + - X 1 Sigma +/ transition moment

    NASA Technical Reports Server (NTRS)

    Park, C.

    1978-01-01

    The sum of the squares of the electronic transition moments for the (E 1 Sigma +) - (X 1 Sigma +) band system of SiO has been determined from absorption measurements conducted in the reflected-shock region of a shock tube. The test gas produced by shock-heating a mixture of SiCl4, N2O, and Ar, and the spectra were recorded photographically in the 150-230-nm wavelength range. The values of the sum of the squares were determined by comparing the measured absorption spectra with those produced by a line-by-line synthetic spectrum calculation. The value so deduced at an r-centroid value of 3.0 bohr was 0.86 + or - 0.10 atomic unit.

  8. Azimuthal asymmetry as a new handle on {sigma}{sub L}/{sigma}{sub T} in diffractive DIS

    SciTech Connect

    Nikolaev, N.N. |; Pronyaev, A.V.; Zakharov, B.G.

    1999-05-01

    We propose a new method of determining R{sup D}={sigma}{sub L}{sup D}/{sigma}{sub T}{sup D} from the dependence of the diffractive cross section on the azimuthal angle between the electron scattering and proton scattering planes. The method is based on our finding of the model independence of the ratio of the LT interference and transverse diffractive structure functions. The predicted azimuthal asymmetry is substantial and can be measured at DESY HERA. We show that the accuracy of our reconstruction of R{sup D} is adequate for a reliable test of an important PQCD prediction of R{sup D}{approx_gt}1 for large {beta}. {copyright} {ital 1999} {ital The American Physical Society}

  9. L(p) approximation capabilities of sum-of-product and sigma-pi-sigma neural networks.

    PubMed

    Long, Jinling; Wu, Wei; Nan, Dong

    2007-10-01

    This paper studies the L(p) approximation capabilities of sum-of-product (SOPNN) and sigma-pi-sigma (SPSNN) neural networks. It is proved that the set of functions that are generated by the SOPNN with its activation function in $L_{loc};p(\\mathcal{R})$ is dense in $L;p(\\mathcal{K})$ for any compact set $\\mathcal{K}\\subset \\mathcal{R};N$, if and only if the activation function is not a polynomial almost everywhere. It is also shown that if the activation function of the SPSNN is in ${L_{loc};\\infty(\\mathcal{R})}$, then the functions generated by the SPSNN are dense in $L;p(\\mathcal{K})$ if and only if the activation function is not a constant (a.e.).

  10. Potential applications for sigma receptor ligands in cancer diagnosis and therapy.

    PubMed

    van Waarde, Aren; Rybczynska, Anna A; Ramakrishnan, Nisha K; Ishiwata, Kiichi; Elsinga, Philip H; Dierckx, Rudi A J O

    2015-10-01

    Sigma receptors (sigma-1 and sigma-2) represent two independent classes of proteins. Their endogenous ligands may include the hallucinogen N,N-dimethyltryptamine (DMT) and sphingolipid-derived amines which interact with sigma-1 receptors, besides steroid hormones (e.g., progesterone) which bind to both sigma receptor subpopulations. The sigma-1 receptor is a ligand-regulated molecular chaperone with various ion channels and G-protein-coupled membrane receptors as clients. The sigma-2 receptor was identified as the progesterone receptor membrane component 1 (PGRMC1). Although sigma receptors are over-expressed in tumors and up-regulated in rapidly dividing normal tissue, their ligands induce significant cell death only in tumor tissue. Sigma ligands may therefore be used to selectively eradicate tumors. Multiple mechanisms appear to underlie cell killing after administration of sigma ligands, and the signaling pathways are dependent both on the type of ligand and the type of tumor cell. Recent evidence suggests that the sigma-2 receptor is a potential tumor and serum biomarker for human lung cancer and an important target for inhibiting tumor invasion and cancer progression. Current radiochemical efforts are focused on the development of subtype-selective radioligands for positron emission tomography (PET) imaging. Right now, the mostpromising tracers are [18F]fluspidine and [18F]FTC-146 for sigma-1 receptors and [11C]RHM-1 and [18F]ISO-1 for the sigma-2 subtype. Nanoparticles coupled to sigma ligands have shown considerable potential for targeted delivery of antitumor drugs in animal models of cancer, but clinical studies exploring this strategy in cancer patients have not yet been reported. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.

  11. Sigma-1 receptor ligands: potential in the treatment of neuropsychiatric disorders.

    PubMed

    Hayashi, Teruo; Su, Tsung-Ping

    2004-01-01

    The sigma receptor was originally proposed to be a subtype of the opioid receptor. However, it is now clear that sigma receptors are unique non-opioid, non-phencyclidine brain proteins. Two types of sigma receptor exist, the sigma-1 receptor and the sigma-2 receptor. sigma-1 receptors have been cloned and their distribution, physiological functions and roles in signal transduction were recently characterised. Certain sex hormones in the brain (neurosteroids) are known to interact with sigma-1 receptors. sigma-1 receptors regulate glutamate NMDA receptor function and the release of neurotransmitters such as dopamine. They are thus proposed to be involved in learning and memory as well as in certain neuropsychiatric disorders. Selective sigma-1 receptor ligands have been suggested to represent a new class of therapeutic agents for neuropsychiatric disorders, although none have yet been introduced into therapeutic use. Early studies showed that psychotomimetic benzomorphans, as well as several antipsychotics, can bind to sigma-1 receptors. As a result of these findings, sigma-1 receptor ligands have been proposed as being of potential use in the treatment of schizophrenia. Nevertheless, the relationship of sigma-1 receptors to the underlying pathogenesis of schizophrenia is still unclear. sigma-1 receptor ligands have failed to improve acute psychotic symptoms of schizophrenia in clinical trials, but, interestingly, a few studies have shown an improvement in negative symptoms in schizophrenic patients. A number of preclinical studies have shown that selective agonists of sigma-1 receptors affect higher-ordered brain functions such as learning and memory, cognition and mood. These studies indicate that sigma-1 receptor agonists may exert therapeutic effects in depression and senile dementia. Indeed, the sigma-1 receptor agonist igmesine, has been shown to improve depression in a clinical trial. The most distinctive feature of the action of sigma-1 receptor ligands is

  12. Quasifree Lambda, Sigma^0, and Sigma^- electroproduction from 1,2H, 3,4He, and Carbon

    SciTech Connect

    F. Dohrmann; A. Ahmidouch; C.S. Armstrong; J. Arrington; R. Asaturyan; S. Avery; K. Bailey; H. Bitao; H. Breuer; D.S. Brown; R. Carlini; J. Cha; N. Chant; E. Christy; A. Cochran; L. Cole; J. Crowder; S. Danagoulian; M. Elaasar; R. Ent; H. Fenker; Y. Fujii; L. Gan; K. Garrow; D.F. Geesaman; P. Gueye; K. Hafidi; W. Hinton; H. Juengst; C. Keppel; Y. Liang; J.H. Liu; A. Lung; D. Mack; P. Markowitz; J. Mitchell; T. Miyoshi; H. Mkrtchyan; S.K. Mtingwa; B. Mueller; G. Niculescu; I. Niculescu; D. Potterveld; B.A. Raue; P.E. Reimer; J. Reinhold; J. Roche; M. Sarsour; Y. Sato; R.E. Segel; A. Semenov; S. Stepanyan; V. Tadevosyan; S. Tajima; L. Tang; A. Uzzle; S. Wood; H. Yamaguchi; C. Yan; L. Yuan; B. Zeidman; M. Zeier; B. Zihlmann

    2007-07-30

    Kaon electroproduction from light nuclei and hydrogen, using 1H, 2H, 3He, 4He, and Carbon targets has been measured at Jefferson Laboratory. The quasifree angular distributions of Lambda and Sigma hyperons were determined at Q^2= 0.35(GeV/c)^2 and W= 1.91GeV. Electroproduction on hydrogen was measured at the same kinematics for reference.

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

    PubMed

    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.

  14. 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

  15. Measurements of sigma (V + D*)/sigma( V) in 9:7 FB-1 at CDF Run II

    NASA Astrophysics Data System (ADS)

    Matera, Keith

    The Standard Model of particle physics has been remarkably successful, but the non-perturbative features of quantum chromodynamics must be tested and modeled with data. There have been many such tests, focused primarily on the use of jet-based probes of heavy flavor (bottom and charm quark) production at hadron colliders. In this thesis, we propose and test a strategy for identifying heavy flavor in events containing a W or Z vector boson (a V boson); this technique probes a much lower energy regime than can be explored by jet-based methods. In a sample of W and Z events skimmed from 9.7 fb-1 of high-pT electron and muon data from CDF Run II pp¯ collisions at center of mass energy sqrt(s) = 1.96 GeV, we identify charm by fully reconstructing D*(2010) → D0(→ Kpi)pis decays at the track level. Using a binned fit of Deltam = m(Kpipis) - m(Kpi) to count reconstructed D* candidates, we then unfold these raw counts with acceptance values derived from Monte Carlo, and present measurements of sigma(W + D*)/sigma(W) and sigma(Z + D*)/sigma(Z) in the W/Z leptonic decay channels. All measurements are found to be in agreement with the predictions of Pythia 6.2 (PDF set CTEQ5L). These results include the first measurement of W/Z + c production in events with zero jet objects at the Tevatron, and the first measurement of W/Z + c production with p T(c) < 15 GeV at the Tevatron.

  16. Efficient star formation in the spiral arms of M51

    NASA Technical Reports Server (NTRS)

    Lord, Steven D.; Young, Judith S.

    1990-01-01

    The molecular, neutral, and ionized hydrogen distributions in the Sbc galaxy M51 (NGC 5194) are compared. To estimate H2 surface densities observations of the CO (J = 1 - 0) transition were made in 60 positions out to a radius of 155 arcsec. Extinction-corrected H-alpha intensities were used to compute the detailed massive star formation rates (MSFRs) in the disk. Estimates of the gas surface density, the MSFR, and the ratio of these quantities, MSFR/sigma(p), were then examined. The spiral arms were found to exhibit an excess gas density, measuring between 1.4 and 1.6 times the interarm values at 45 arcsec resolution. The total (arm and interarm) gas content and massive star formation rates in concentric annuli in the disk of M51 were computed. The two quantities fall off together with radius, yielding a relatively constant MSFR/sigma(p) with radius. This behavior is not explained by current models of star formation in galactic disks.

  17. 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.

  18. 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.

  19. Fourier Transform Spectroscopy of Chemiluminescence from the SrO A(1)Sigma(+)-X(1)Sigma(+) Transition.

    PubMed

    Li; Skelton; Focsa; Pinchemel; Bernath

    2000-09-01

    The A(1)Sigma(+)-X(1)Sigma(+) chemiluminescence spectrum of SrO was observed using a Fourier transform spectrometer. SrO was produced in a Broida-type oven from the Sr + N(2)O reaction. A total of 75 bands from (88)SrO, (87)SrO, and (86)SrO were measured in the range of 7600-13 600 cm(-1) at a resolution of 0.04 cm(-1). The vibrational levels of the ground state were observed up to v" = 12 and over 10 000 rovibrational lines with J as high as 153 were analyzed at a precision of about 0.005 cm(-1). Significantly improved spectral constants for the ground state were obtained by representing the perturbed excited state by term values and by adding the known microwave data and infrared data to our fit. Strong perturbations were observed in the upper A state. The vibrational levels of the A(1)Sigma(+) state were measured up to v' = 8 and some new perturbations are reported. Copyright 2000 Academic Press.

  20. EXOTIC PARTICLE SEARCHES WITH STAR AT RHIC.

    SciTech Connect

    KANABA,S.

    2004-03-15

    We present preliminary results of the STAR experiment at RHIC on exotic particle searches in minimum bias Au + Au collisions at {radical} s{sub NN} = 200 GeV. We observe a narrow peak at 1734 {+-} 0.5 {+-} 5 MeV in the {lambda}K{sub s}{sup 0} invariant mass with width consistent with the experimental resolution of about 6 MeV within the errors. The statistical significance can be quantified between 3 and 6 {sigma} depending on cuts and methods. If this peak corresponds to a real particle state it would be a candidate for the N{sup 0} or the {Xi}{sup 0} I = 1/2 pentaquark states.

  1. Massive Star Makes Waves

    NASA Image and Video Library

    2012-12-18

    The giant star Zeta Ophiuchi, a young, large and hot star located around 370 light-years away, is having a hocking effect on the surrounding dust clouds in this infrared image from NASA Spitzer Space Telescope.

  2. Sloshing Star Goes Supernova

    NASA Image and Video Library

    2014-02-19

    NuSTAR has provided the first observational evidence in support of a theory that says exploding stars slosh around before detonating. That theory, referred to as mild asymmetries, is shown here in a simulation by Christian Ott.

  3. Assembly Line of Stars

    NASA Image and Video Library

    2010-05-06

    This image from NASA Herschel, in the constellation of Vulpecula, shows an entire assembly line of newborn stars. The diffuse glow reveals the widespread cold reservoir of raw material that our Milky Way galaxy has in stock for building stars.

  4. Star formation: Cosmic feast

    NASA Astrophysics Data System (ADS)

    Scaringi, Simone

    2017-03-01

    Low-mass stars form through a process known as disk accretion, eating up material that orbits in a disk around them. It turns out that the same mechanism also describes the formation of more massive stars.

  5. Star formation: Cosmic feast

    NASA Astrophysics Data System (ADS)

    Scaringi, Simone

    2016-11-01

    Low-mass stars form through a process known as disk accretion, eating up material that orbits in a disk around them. It turns out that the same mechanism also describes the formation of more massive stars.

  6. 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

  7. AgSTAR Accomplishments

    EPA Pesticide Factsheets

    Showcases AgSTAR's accomplishments reducing greenhouse gas emissions in the agriculture sector. Through outreach, education, training, and other tools, AgSTAR continues to help evaluate, construct, and maintain anaerobic digesters on livestock farms.

  8. 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.

  9. 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.

  10. White Dwarf Stars

    NASA Image and Video Library

    1999-12-01

    Peering deep inside a cluster of several hundred thousand stars, NASA Hubble Space Telescope has uncovered the oldest burned-out stars in our Milky Way Galaxy, giving astronomers a fresh reading on the age of the universe.

  11. Another Death Star?

    NASA Image and Video Library

    2012-12-03

    Although Mimas holds the unofficial designation of Death Star moon, Tethys is seen here also vaguely resembling the space station from Star Wars. Apparently, Tethys doesnt want Mimas to have all the fun!

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. An RpoS (sigmaS) homologue regulates acylhomoserine lactone-dependent autoinduction in Ralstonia solanacearum.

    PubMed

    Flavier, A B; Schell, M A; Denny, T P

    1998-05-01

    Many bacteria sense an appropriate growth condition or a critical population density for gene expression by producing acylhomoserine lactones (acyl-HSLs) that act as intercellular autoinduction signals. We recently showed that, in Ralstonia (Pseudomonas) solanacearum, a phytopathogenic bacterium, acyl-HSL production requires soll, which encodes a putative acyl-HSL synthase, and that its expression is positively regulated by the acyl-HSL-responsive SolR transcriptional regulator. This acyl-HSL-dependent autoinduction system is noteworthy because (i) it is regulated by a 'higher level' autoinducer system (responsive to 3-hydroxypalmitic acid methyl ester) via PhcA, a LysR-type transcriptional regulator and (ii) acyl-HSL production requires two additional unlinked loci. As reported here, cloning and sequencing of one of these other loci revealed that it encodes a homologue of RpoS, an alternative sigma factor (sigmaS) that in other bacteria activates gene expression during stationary phase or in response to stress conditions. R. solanacearum RpoS (RpoS(Rso)) was demonstrated to function as a sigma factor because when introduced in trans into an Escherichia coli rpoS mutant it largely restored expression of the RpoS-dependent bolAp1 gene. Mutation of rpoS(Rso) in R. solanacearum reduced survival during starvation and low pH conditions, but did not affect survival during exposure to hydrogen peroxide, high osmolarity or high temperature. This mutant was also altered in its production of several virulence factors and wilted tomato plants several days more slowly than the wild-type parent. Transcription of solR and soll were decreased in an rpoS(Rso) background (thereby reducing acyl-HSL production), but neither mutations in solR, soll or phcA nor addition of acyl-HSLs affected rpoS(Rso) expression. Therefore, in R. solanacearum the acyl-HSL-dependent autoinduction system is controlled both by a second autoinduction system and by the RpoS(Rso) sigma factor.

  18. The Escherichia coli regulator of sigma 70 protein, Rsd, can up-regulate some stress-dependent promoters by sequestering sigma 70.

    PubMed

    Mitchell, Jennie E; Oshima, Taku; Piper, Sarah E; Webster, Christine L; Westblade, Lars F; Karimova, Gouzel; Ladant, Daniel; Kolb, Annie; Hobman, Jon L; Busby, Stephen J W; Lee, David J

    2007-05-01

    The Escherichia coli Rsd protein forms complexes with the RNA polymerase sigma(70) factor, but its biological role is not understood. Transcriptome analysis shows that overexpression of Rsd causes increased expression from some promoters whose expression depends on the alternative sigma(38) factor, and this was confirmed by experiments with lac fusions at selected promoters. The LP18 substitution in Rsd increases the Rsd-dependent stimulation of these promoter-lac fusions. Analysis with a bacterial two-hybrid system shows that the LP18 substitution in Rsd increases its interaction with sigma(70). Our experiments support a model in which the role of Rsd is primarily to sequester sigma(70), thereby increasing the levels of RNA polymerase containing the alternative sigma(38) factor.

  19. 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…

  20. 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…

  1. Seeing Stars in Serpens

    NASA Image and Video Library

    2006-12-08

    Infant stars are glowing gloriously in this image of the Serpens star-forming region, captured by NASA 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.

  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. The sigma-1 receptor enhances brain plasticity and functional recovery after experimental stroke.

    PubMed

    Ruscher, Karsten; Shamloo, Mehrdad; Rickhag, Mattias; Ladunga, Istvan; Soriano, Liza; Gisselsson, Lennart; Toresson, Håkan; Ruslim-Litrus, Lily; Oksenberg, Donna; Urfer, Roman; Johansson, Barbro B; Nikolich, Karoly; Wieloch, Tadeusz

    2011-03-01

    Stroke leads to brain damage with subsequent slow and incomplete recovery of lost brain functions. Enriched housing of stroke-injured rats provides multi-modal sensorimotor stimulation, which improves recovery, although the specific mechanisms involved have not been identified. In rats housed in an enriched environment for two weeks after permanent middle cerebral artery occlusion, we found increased sigma-1 receptor expression in peri-infarct areas. Treatment of rats subjected to permanent or transient middle cerebral artery occlusion with 1-(3,4-dimethoxyphenethyl)-4-(3-phenylpropyl)piperazine dihydrochloride, an agonist of the sigma-1 receptor, starting two days after injury, enhanced the recovery of lost sensorimotor function without decreasing infarct size. The sigma-1 receptor was found in the galactocerebroside enriched membrane microdomains of reactive astrocytes and in neurons. Sigma-1 receptor activation increased the levels of the synaptic protein neurabin and neurexin in membrane rafts in the peri-infarct area, while sigma-1 receptor silencing prevented sigma-1 receptor-mediated neurite outgrowth in primary cortical neuronal cultures. In astrocytic cultures, oxygen and glucose deprivation induced sigma-1 receptor expression and actin dependent membrane raft formation, the latter blocked by sigma-1 receptor small interfering RNA silencing and pharmacological inhibition. We conclude that sigma-1 receptor activation stimulates recovery after stroke by enhancing cellular transport of biomolecules required for brain repair, thereby stimulating brain plasticity. Pharmacological targeting of the sigma-1 receptor provides new opportunities for stroke treatment beyond the therapeutic window of neuroprotection.

  4. 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.

  5. 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.

  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. sigma Receptor activation blocks potassium channels and depresses neuroexcitability in rat intracardiac neurons.

    PubMed

    Zhang, Hongling; Cuevas, Javier

    2005-06-01

    The sigma receptors have been implicated in the regulation of the cardiovascular system, and sigma-1 receptor transcripts have been found in parasympathetic intracardiac neurons. However, the cellular function of sigma-1 receptors in these cells remains to be determined. Effects of sigma receptor activation on voltage-activated K(+) channels and action potential firing were studied in isolated intracardiac neurons using whole-cell patch-clamp recording techniques. Activation of sigma receptors reversibly blocked delayed outwardly rectifying potassium channels, large conductance Ca(2+)-sensitive K(+) channels, and the M-current with maximal inhibition >80%. The inhibition of K(+) channels by sigma ligands was dose-dependent, and the rank order potency of (+)-pentazocine > ibogaine > 1,3-di-O-tolyguanidin (DTG) suggests that the effect is mediated by sigma-1 receptor activation. Preincubation of neurons with the irreversible sigma receptor antagonist metaphit blocked DTG-induced inhibition of K(+) channels, confirming that the effect is mediated by sigma receptor activation. Although bath application of sigma ligands depolarized intracardiac neurons, the number of action potentials fired by the cells in response to depolarizing current pulses was decreased in the presence of these drugs. Neither dialysis of the neurons nor application of intracellular 5'-O-(2-thiodiphosphate) trilithium salt inhibited the effect of sigma receptors on K(+) channels, which suggests that the signal transduction pathway does not involve a diffusible cytosolic second messenger or a G protein. Together, these data suggest that sigma-1 receptors are directly coupled to K(+) channels in intracardiac neurons. Furthermore, activation of sigma-1 receptors depresses the excitability of intracardiac neurons and is thus likely to block parasympathetic input to the heart.

  8. Development and initial test of the University of Wisconsin global isentropic-sigma model

    NASA Technical Reports Server (NTRS)

    Zapotocny, Tom H.; Johnson, Donald R.; Reames, Fred M.

    1994-01-01

    The description of a global version of the University of Wisconsin (UW) hybrid isentropic-sigma (theta-sigma) model and the results from an initial numerical weather prediction experiment are presented in this paper. The main objectives of this initial test are to (1) discuss theta-sigma model development and computer requirements, (2) demonstrate the ability of the UW theta-sigma model for global numerical weather prediction using realistic orography and parameterized physical processes, and (3) compare the transport of an inert trace constituent against a nominally 'identical' sigma coordinate model. Initial and verifying data for the 5-day simulations presented in this work were supplied by the Goddard Earth Observing System (GEOS-1) data assimilation system. The time period studied is 1-6 February 1985. This validation experiment demonstrates that the global UW theta-sigma model produces a realistic 5-day simulation of the mass and momentum distributions when compared to both the identical sigma model and GEOS-1 verification. Root-mean-square errors demonstrate that the theta-sigma model is slightly more accurate than the nominally identical sigma model with respect to standard synoptic variables. Of particular importance, the UW theta-sigma model displays a distinct advantage over the conventional sigma model with respect to the prognostic simulation of inert trace constituent transport in amplifying baroclinic waves of the extratropics. This is especially true in the upper troposphere and stratosphere where the spatial integrity and conservation of an inert trace constituent is severely compromised in the sigma model compared to the theta-sigma model.

  9. Improving ED specimen TAT using Lean Six Sigma.

    PubMed

    Sanders, Janet H; Karr, Tedd

    2015-01-01

    Lean and Six Sigma are continuous improvement methodologies that have garnered international fame for improving manufacturing and service processes. Increasingly these methodologies are demonstrating their power to also improve healthcare processes. The purpose of this paper is to discuss a case study for the application of Lean and Six Sigma tools in the reduction of turnaround time (TAT) for Emergency Department (ED) specimens. This application of the scientific methodologies uncovered opportunities to improve the entire ED to lab system for the specimens. This case study provides details on the completion of a Lean Six Sigma project in a 1,000 bed tertiary care teaching hospital. Six Sigma's Define, Measure, Analyze, Improve, and Control methodology is very similar to good medical practice: first, relevant information is obtained and assembled; second, a careful and thorough diagnosis is completed; third, a treatment is proposed and implemented; and fourth, checks are made to determine if the treatment was effective. Lean's primary goal is to do more with less work and waste. The Lean methodology was used to identify and eliminate waste through rapid implementation of change. The initial focus of this project was the reduction of turn-around-times for ED specimens. However, the results led to better processes for both the internal and external customers of this and other processes. The project results included: a 50 percent decrease in vials used for testing, a 50 percent decrease in unused or extra specimens, a 90 percent decrease in ED specimens without orders, a 30 percent decrease in complete blood count analysis (CBCA) Median TAT, a 50 percent decrease in CBCA TAT Variation, a 10 percent decrease in Troponin TAT Variation, a 18.2 percent decrease in URPN TAT Variation, and a 2-5 minute decrease in ED registered nurses rainbow draw time. This case study demonstrated how the quantitative power of Six Sigma and the speed of Lean worked in harmony to improve

  10. 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; hide

    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.

  11. The Herschel Open Time Key Project; DUst Around NEarby Stars: Results from the Complete Survey

    NASA Astrophysics Data System (ADS)

    Danchi, William C.; Eiroa, C.; Consortium, DUNES

    2013-01-01

    The Herschel DUst Around Nearby Stars (DUNES) survey (Eiroa et al. 2010) was designed to address several fundamental questions regarding debris disks around nearby solar type stars, in order to put the Solar System into context. Our goals were to: (1) determine the fraction of stars with faint, Edgeworth-Kuiper Belt (EKB)-like disks, (2) explore collisional and dynamical evolution of EKB analogues, (3) observe dust properties and size distribution, and (4) determine the incidence of EKB-like disks vs. presence of planets. The final sample of stars directly observed by DUNES included 133 stars, including 27 F-type, 52 G-type and 54 K-type stars within 20 pc of the Sun. The integration time was set in order to make a 5-sigma detection of the expected photospheric emission at 100 and 160 microns, using the PACS instrument. In addition, 106 stars observed by DEBRIS survey (Mathews et al. 2010) satisfying the photospheric detection condition are shared targets, specifically 83 FGK stars - 51 F, 24 G and 8 K (the rest are A and M stars). We report the main conclusions from the survey including the frequency of detection of debris disks as a function of fractional luminosity of the dust, Ld/L*, and correlations of Ld/L* with metallicity, bolometric luminosity, effective temperature, and stellar age.

  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. [Improving inpatient pharmacoterapeutic process by Lean Six Sigma methodology].

    PubMed

    Font Noguera, I; Fernández Megía, M J; Ferrer Riquelme, A J; Balasch I Parisi, S; Edo Solsona, M D; Poveda Andres, J L

    2013-01-01

    Lean Six Sigma methodology has been used to improve care processes, eliminate waste, reduce costs, and increase patient satisfaction. To analyse the results obtained with Lean Six Sigma methodology in the diagnosis and improvement of the inpatient pharmacotherapy process during structural and organisational changes in a tertiary hospital. 1.000 beds tertiary hospital. prospective observational study. The define, measure, analyse, improve and control (DMAIC), were deployed from March to September 2011. An Initial Project Charter was updated as results were obtained. 131 patients with treatments prescribed within 24h after admission and with 4 drugs. safety indicators (medication errors), and efficiency indicators (complaints and time delays). Proportion of patients with a medication error was reduced from 61.0% (25/41 patients) to 55.7% (39/70 patients) in four months. Percentage of errors (regarding the opportunities for error) decreased in the different phases of the process: Prescription: from 5.1% (19/372 opportunities) to 3.3% (19/572 opportunities); Preparation: from 2.7% (14/525 opportunities) to 1.3% (11/847 opportunities); and administration: from 4.9% (16/329 opportunities) to 3.0% (13/433 opportunities). Nursing complaints decreased from 10.0% (2119/21038 patients) to 5.7% (1779/31097 patients). The estimated economic impact was 76,800 euros saved. An improvement in the pharmacotherapeutic process and a positive economic impact was observed, as well as enhancing patient safety and efficiency of the organization. Standardisation and professional training are future Lean Six Sigma candidate projects. Copyright © 2012 SECA. Published by Elsevier Espana. All rights reserved.

  14. Improving patient satisfaction with pain management using Six Sigma tools.

    PubMed

    DuPree, Erin; Martin, Lisa; Anderson, Rebecca; Kathuria, Navneet; Reich, David; Porter, Carol; Chassin, Mark R

    2009-07-01

    Patient satisfaction as a direct and public measure of quality of care is changing the way hospitals address quality improvement. The feasibility of using the Six Sigma DMAIC (Define, Measure, Analyze, Improve, Control) methodology to improve patient satisfaction as it relates to pain management was evaluated. This project used the DMAIC methodology to improve patients' overall satisfaction with pain management on two inpatient units in an urban academic medical center. Pre- and postintervention patient surveys were conducted. The DMAIC methodology provided a data-driven structure to determine the optimal improvement strategies, as well as a long-term plan for maintaining any improvements. In addition, the Change Acceleration Process (CAP) was used throughout the project's various DMAIC stages to further the work of the team by creating a shared need to meet the objectives of the project. Overall satisfaction with pain management "excellent" ratings increased from 37% to 54%. Both units surpassed the goal of at least 50% of responses in the "excellent" category. Several key drivers of satisfaction with pain management were uncovered in the Analyze phase of the project, and each saw rating increases from the pre-intervention to postintervention surveys. Ongoing monitoring by the hospital inpatient satisfaction survey showed that the pain satisfaction score improved in subsequent quarters as compared with the pre-intervention period. The Six Sigma DMAIC methodology can be used successfully to improve patient satisfaction. The project led to measurable improvements in patient satisfaction with pain management, which have endured past the duration of the Six Sigma project. The Control phase of DMAIC allows the improvements to be incorporated into daily operations.

  15. 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.

  16. SigmaB-dependent and sigmaB-independent mechanisms contribute to transcription of Listeria monocytogenes cold stress genes during cold shock and cold growth.

    PubMed

    Chan, Yvonne C; Boor, Kathryn J; Wiedmann, Martin

    2007-10-01

    The role of the stress response regulator sigma(B) (encoded by sigB) in directing the expression of selected putative and confirmed cold response genes was evaluated using Listeria monocytogenes 10403S and an isogenic DeltasigB mutant, which were either cold shocked at 4 degrees C in brain heart infusion (BHI) broth for up to 30 min or grown at 4 degrees C in BHI for 12 days. Transcript levels of the housekeeping genes rpoB and gap, the sigma(B)-dependent genes opuCA and bsh, and the cold stress genes ltrC, oppA, and fri were measured using quantitative reverse transcriptase PCR. Transcriptional start sites for ltrC, oppA, and fri were determined using rapid amplification of cDNA ends PCR. Centrifugation was found to rapidly induce sigma(B)-dependent transcription, which necessitated the use of centrifugation-independent protocols to evaluate the contributions of sigma(B) to transcription during cold shock. Our data confirmed that transcription of the cold stress genes ltrC and fri is at least partially sigma(B) dependent and experimentally identified a sigma(B)-dependent ltrC promoter. In addition, our data indicate that (i) while sigma(B) activity is induced during 30 min of cold shock, this cold shock does not induce the transcription of sigma(B)-dependent or -independent cold shock genes; (ii) sigma(B) is not required for L. monocytogenes growth at 4 degrees C in BHI; and (iii) transcription of the putative cold stress genes opuCA, fri, and oppA is sigma(B) independent during growth at 4 degrees C, while both bsh and ltrC show growth phase and sigma(B)-dependent transcription during growth at 4 degrees C. We conclude that sigma(B)-dependent and sigma(B)-independent mechanisms contribute to the ability of L. monocytogenes to survive and grow at low temperatures.

  17. 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.

  18. Inverse magnetic catalysis in the linear sigma model

    NASA Astrophysics Data System (ADS)

    Ayala, A.; Loewe, M.; Zamora, R.

    2016-05-01

    We compute the critical temperature for the chiral transition in the background of a magnetic field in the linear sigma model, including the quark contribution and the thermo-magnetic effects induced on the coupling constants at one loop level. For the analysis, we go beyond mean field aproximation, by taking one loop thermo-magnetic corrections to the couplings as well as plasma screening effects for the boson's masses, expressed through the ring diagrams. We found inverse magnetic catalysis, i.e. a decreasing of the critical chiral temperature as function of the intensity of the magnetic field, which seems to be in agreement with recent results from the lattice community.

  19. O(N) Generalized nonlinear sigma model and its applications

    SciTech Connect

    Ferrari, F. Paturej, J.; Vilgis, T. A.

    2010-02-15

    In this work the results of an interdisciplinary research between field theory and statistical mechanics will be presented. It is shown that the dynamics of an inextensible chain is described by a slight generalization of the O(d) nonlinear sigma model. It is checked, that in the large time limit the correct equilibrium distribution is reached. Our approach is based on path integrals, but it may be also connected to the usual description of the dynamics of a chain as a diffusion stochastic process. Some applications of our results will be discussed, like for instance the calculation of the average distance between two polymer segments.

  20. 3D Loop Models and the CPn-1 Sigma Model

    NASA Astrophysics Data System (ADS)

    Nahum, Adam; Chalker, J. T.; Serna, P.; Ortuño, M.; Somoza, A. M.

    2011-09-01

    Many statistical mechanics problems can be framed in terms of random curves; we consider a class of three-dimensional loop models that are prototypes for such ensembles. The models show transitions between phases with infinite loops and short-loop phases. We map them to CPn-1 sigma models, where n is the loop fugacity. Using Monte Carlo simulations, we find continuous transitions for n=1, 2, 3, and first order transitions for n≥5. The results are relevant to line defects in random media, as well as to Anderson localization and (2+1)-dimensional quantum magnets.

  1. Solitons in a. sigma. model with a fermionic determinant

    SciTech Connect

    Moussallam, B. )

    1989-11-15

    We develop a numerical technique to calculate the fermionic determinant for soliton states with a hedgehog'' symmetry in three space dimensions based on the phase-shift representation. How the divergence builds up in this approach is clarified. An extrapolation procedure is devised which yields an accurately cutoff-independent finite answer. We find that the nonlinear {sigma} model coupled to colored fermions does not seem to support soliton solutions although solutions exist if only scale variations are taken into account. Even on adding a Skyrme quartic term to the action, we find oscillating configurations which are able to lower the energy of the system, possibly without bound.

  2. Vacuum structure in the quantum nonlinear. sigma. -model

    SciTech Connect

    Asano, H. ); Kanada, H.; So, H. )

    1991-12-14

    In this paper the vacuum structure with a non-trivial winding number (the baryon number) of a quantum nonlinear {sigma}-model is investigated. Some falling paths to the vacuum are found in a finite-dimensional subspace of the infinite-dimensional configuration space. It is also shown by numerical calculation that the anti-baryon density is appeared in the outer region on the way of some paths falling into the vacuum. In addition, we also discuss some configurations without hedgehog ansatz.

  3. Applying Lean Six Sigma to improve medication management.

    PubMed

    Nayar, Preethy; Ojha, Diptee; Fetrick, Ann; Nguyen, Anh T

    2016-01-01

    A significant proportion of veterans use dual care or health care services within and outside the Veterans Health Administration (VHA). In this study conducted at a VHA medical center in the USA, the authors used Lean Six Sigma principles to develop recommendations to eliminate wasteful processes and implement a more efficient and effective process to manage medications for dual care veteran patients. The purpose of this study is to: assess compliance with the VHA's dual care policy; collect data and describe the current process for co-management of dual care veterans' medications; and draft recommendations to improve the current process for dual care medications co-management. Input was obtained from the VHA patient care team members to draw a process map to describe the current process for filling a non-VHA prescription at a VHA facility. Data were collected through surveys and direct observation to measure the current process and to develop recommendations to redesign and improve the process. A key bottleneck in the process that was identified was the receipt of the non-VHA medical record which resulted in delays in filling prescriptions. The recommendations of this project focus on the four domains of: documentation of dual care; veteran education; process redesign; and outreach to community providers. This case study describes the application of Lean Six Sigma principles in one urban Veterans Affairs Medical Center (VAMC) in the Mid-Western USA to solve a specific organizational quality problem. Therefore, the findings may not be generalizable to other organizations. The Lean Six Sigma general principles applied in this project to develop recommendations to improve medication management for dual care veterans are applicable to any process improvement or redesign project and has valuable lessons for other VAMCs seeking to improve care for their dual care veteran patients. The findings of this project will be of value to VA providers and policy makers and health

  4. A Star Close Encounter

    NASA Image and Video Library

    2006-10-03

    The potential planet-forming disk (or "protoplanetary disk") of a sun-like star is being violently ripped away by the powerful winds of a nearby hot O-type star in this image from NASA's Spitzer Space Telescope. At up to 100 times the mass of sun-like stars, O stars are the most massive and energetic stars in the universe. The O star can be seen to the right of the image, as the large orange spot with the white center. To the left, the comet-like structure is actually a neighboring solar system that is being destroyed by the O star's powerful winds and intense ultraviolet light. In a process called "photoevaporation," immense output from the O star heats up the nearby protoplanetary disk so much that gas and dust boil off, and the disk can no longer hold together. Photon (or light) blasts from the O star then strip the potential planet-forming disk off its neighbor star by blowing away evaporated material. This effect is illustrated in the smaller system's comet-like structure. The system is located about 2,450 light-years away in the star-forming cloud IC 1396. The image was taken with Spitzer's multiband imaging photometer instrument at 24 microns. The picture is a pseudo-color stretch representing intensity. Yellow and white represent hot areas, whereas purple and blue represent relatively cooler, fainter regions.

  5. 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.

  6. Spectrophotometry of Symbiotic Stars

    NASA Astrophysics Data System (ADS)

    Boyd, David

    2017-06-01

    Symbiotic stars are fascinating objects - complex binary systems comprising a cool red giant star and a small hot object, often a white dwarf, both embedded in a nebula formed by a wind from the giant star. UV radiation from the hot star ionises the nebula producing a range of emission lines. These objects have composite spectra with contributions from both stars plus the nebula and these spectra can change on many timescales. Being moderately bright, they lend themselves well to amateur spectroscopy. This paper describes the symbiotic star phenomenon, shows how spectrophotometry can be used to extract astrophysically useful information about the nature of these systems, and gives results for three symbiotic stars based on the author's observations.

  7. 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.

  8. The velocity dispersion of the caustic network due to random motion of individual stars in the lensing galaxy

    NASA Technical Reports Server (NTRS)

    Kundik, Tomislav; Witt, Hans J.; Chang, Kyongae

    1993-01-01

    We present a method of computing the velocity distribution of the caustic network due to the random motion of stars in the lensing galaxy. This method is illustrated on the example of the two-point mass lens and then applied to a large sample of stars. We conclude that the proper motion of the stars increases significantly the frequency of the high magnification events in comparison with a static lens configuration with constant stream or constant bulk velocity. The stream velocity is the velocity of the star field relative to the global bulk velocity of the galaxy. We show that the global bulk and the stream velocity of the star field have to be considered separately for any microlensing situation. The higher the surface mass density of the stars in the lensing galaxy, the higher the influence of proper motion of stars on the statistics of high magnification events. The influence of a Gaussian velocity distribution of the stars in the lensing galaxy compared with a constant stream velocity of the stars increases the number of high magnification events by a factor 1.30 +/- 0.06 for a normalized surface density of the stars cr = 0.1 and by a factor 1.7 +/- 0.1 for sigma = 0.5. This means that for some microlensing situations the proper motion of the stars in a lensing galaxy has to be considered for exact microlensing predictions.

  9. Computing system failure probabilities: a comparison of SIGMA PI with other methods

    SciTech Connect

    Thatcher, R.M.; Corynen, G.C.

    1985-08-01

    SIGMA PI is the fastest method available today of accurately calculating probabilities associated with large fault trees. To demonstrate this, we describe the major problems that have prevented successful evaluation of these probabilities by other methods in the past. Then, we describe how SIGMA PI addresses all of these problems, and we compare the performance of SIGMA PI with that of leading alternative methods under selected problem scenarios. 13 refs., 3 figs., 2 tabs.

  10. Approximating the Poisson Scan and (lambda-sigma) Acoustic Detection Model with the Random Search Formula

    DTIC Science & Technology

    2009-12-01

    of area search with acoustic sensors modeled by the Poisson Scan model and the Lambda-Sigma model. Detection time results are compared to those...MATLAB simulation of area search with acoustic sensors modeled by the Poisson Scan model and the Lambda-Sigma  model. Detection time results are...study, the author develops a MATLAB simulation of area search with acoustic sensors modeled by the Poisson Scan and the Lambda-Sigma  models. Both

  11. [Involvement of sigma S and sigma 70 subunits of RNA polymerase and the CRP protein in the regulation of microcin C51 operon expression].

    PubMed

    Veselovskiĭ, A M; Bass, I A; Zolotukhina, M A; Mironov, A S; Metlitskaia, A Z; Khmel', I A

    2004-11-01

    Expression of the microcin C51 operon in Escherichia coli cells is activated during cell entry into the stationary growth phase and depends on the sigmaS subunit of RNA polymerase (RpoS). The null rpoS mutations retained the residual expression level of the transcriptional P(mcc)-lac fusion, which indicates that other sigma subunit can participate in the regulation of transcription of the microcin C51 operon. Data presented in this work show that the overproduction of sigma70 in rpoS- cells diminished the level of P(mcc)-lac expression, as in wild-type cells, which seems to be the consequence of competition between sigma factors for a limited number of core RNA polymerase molecules. In the presence of the rpoD800 mutation that renders sigma70 temperature-sensitive, expression of P(mcc)-lac was not induced in the phase of delayed culture growth at nonpermissive temperature, which indicates that sigma70 is indispensable for microcin operon expression. Point substitutions in the -10 P(mcc) region, leading to the formation of 5'-TGaTATAAT-3' site, enhanced promoter activity but did not affect the relationship between P(mcc)-lac transcription and growth phase, sigmaS, and the activator protein CRP. The activator protein CRP was shown to bind a DNA fragment containing the TGTGA(AATGAA)TCTAT site in the -59.5 bp position relative to the start site of transcription. Mutation in the ssrI gene encoding 6S RNA did not disturb P9mcc)-lac expression; these results indicate that 6S RNA does not participate in the regulation of microcin C51 operon expression.

  12. Applying Lean Six Sigma methodology to reduce cesarean section rate.

    PubMed

    Chai, Ze-Ying; Hu, Hua-Min; Ren, Xiu-Ling; Zeng, Bao-Jin; Zheng, Ling-Zhi; Qi, Feng

    2017-06-01

    This study aims to reduce cesarean section rate and increase rate of vaginal delivery. By using Lean Six Sigma (LSS) methodology, the cesarean section rate was investigated and analyzed through a 5-phase roadmap consisting of Define, Measure, Analyze, Improve, and Control. The principal causes of cesarean section were identified, improvement measures were implemented, and the rate of cesarean section before and after intervention was compared. After patients with a valid medical reason for cesarean were excluded, the main causes of cesarean section were maternal request, labor pain, parturient women assessment, and labor observation. A series of measures was implemented, including an improved parturient women assessment system, strengthened pregnancy nutrition guidance, implementation of painless labor techniques, enhanced midwifery team building, and promotion of childbirth-assist skills. Ten months after introduction of the improvement measures, the cesarean section rate decreased from 41.83% to 32.00%, and the Six Sigma score (ie, Z value) increased from 1.706 to 1.967 (P < .001). LSS is an effective way to reduce the rate of cesarean section. © 2016 John Wiley & Sons, Ltd.

  13. 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.

  14. 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).

  15. [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.

  16. Roles of sigma-1 receptors in Alzheimer's disease.

    PubMed

    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.

  17. A high-sigma model of pulsar wind nebulae

    NASA Astrophysics Data System (ADS)

    Lyutikov, Maxim

    2010-07-01

    Pulsars and central engines of long gamma-ray bursts - collapsars - may produce highly magnetized (Poynting-flux-dominated) outflows expanding in dense surroundings (interstellar medium or stellar material). For certain injection conditions, the magnetic flux of the wind cannot be accommodated within the cavity. In this case, ideal (non-dissipative) magnetohydrodynamics models, similar to the Kennel & Coroniti model of the Crab nebula, break down (the so-called `sigma problem'). This is typically taken to imply that the wind should become particle-dominated on scales much smaller than the size of the cavity. The wind is then slowed down by a fluid-type (low magnetization) reverse shock. Recent Fermi results, indicating that the synchrotron spectrum of the Crab nebula extends well beyond the upper limit of the most efficient radiation-reaction-limited acceleration, contradict the presence of a low-sigma reverse shock. We propose an alternative possibility, that in nearly aligned pulsars the excessive magnetic flux is destroyed in a reconnection-like process in two regions: near the rotational axis and near the equator. We construct an example of such a highly magnetized wind having two distinct reconnection regions and suggest that these reconnection sites are observed as tori and jets in pulsar wind nebulae. The model reproduces, qualitatively, the observed morphology of the Crab nebula. In parts of the nebula dissipation occurs in a relativistically moving wind, alleviating requirements on the acceleration rate.

  18. LEAN SIX SIGMA TECHNIQUES TO IMPROVE OPHTHALMOLOGY CLINIC EFFICIENCY.

    PubMed

    Ciulla, Thomas A; Tatikonda, Mohan V; ElMaraghi, Yehya A; Hussain, Rehan M; Hill, Amanda L; Clary, Julie M; Hattab, Eyas

    2017-07-18

    Ophthalmologists serve an increasing volume of a growing elderly population undergoing increasingly complex outpatient medical care, including extensive diagnostic testing and treatment. The resulting prolonged patient visit times ("patient flow times") limit quality, patient and employee satisfaction, and represent waste. Lean Six Sigma process improvement was used in a vitreoretinal practice to decrease patient flow time, demonstrating that this approach can yield significant improvement in health care. Process flow maps were created to determine the most common care pathways within clinic. Three months' visits from the electronic medical record system, which tracks patient task times at each process step in the office were collected. Care tasks and care pathways consuming the greatest time and variation were identified and modified. Follow-up analysis from 6 weeks' visits was conducted to assess improvement. Nearly all patients took one of five paths through the office. Patient flow was redesigned to reduce waiting room time by having staff members immediately start patients into one of those five paths; staffing was adjusted to address high demand tasks, and scheduling was optimized around derived predictors of patient flow times. Follow-up analysis revealed a statistically significant decline in mean patient flow time by 18% and inpatient flow time SD by 4.6%. Patient and employee satisfaction scores improved. Manufacturing industry techniques, such as Lean and Six Sigma, can be used to improve patient care, minimize waste, and enhance patient and staff satisfaction in outpatient clinics.

  19. 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

  20. Gauged linear sigma model and pion-pion scattering

    SciTech Connect

    Fariborz, Amir H.; Schechter, Joseph; Shahid, M. Naeem

    2009-12-01

    A simple gauged linear sigma model with several parameters to take the symmetry breaking and the mass differences between the vector meson and the axial vector meson into account is considered here as a possibly useful 'template' for the role of a light scalar in QCD as well as for (at a different scale) an effective Higgs sector for some recently proposed walking technicolor models. An analytic procedure is first developed for relating the Lagrangian parameters to four well established (in the QCD application) experimental inputs. One simple equation distinguishes three different cases: i. QCD with axial vector particle heavier than vector particle, ii. possible technicolor model with vector particle heavier than the axial vector one, iii. the unphysical QCD case where both the Kawarabayashi-Suzuki-Riazuddin-Fayazuddin and Weinberg relations hold. The model is applied to the s-wave pion-pion scattering in QCD. Both the near threshold region and (with an assumed unitarization) the 'global' region up to about 800 MeV are considered. It is noted that there is a little tension between the choice of 'bare' sigma mass parameter for describing these two regions. If a reasonable 'global' fit is made, there is some loss of precision in the near threshold region.

  1. 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.

  2. Nonlinear sigma models with compact hyperbolic target spaces

    DOE PAGES

    Gubser, Steven; Saleem, Zain H.; Schoenholz, Samuel S.; ...

    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

  3. 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.

  4. Nonlinear sigma models with compact hyperbolic target spaces

    SciTech Connect

    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 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. 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.

  5. 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.

  6. EBSD spatial resolution for detecting sigma phase in steels.

    PubMed

    Bordín, S Fernandez; Limandri, S; Ranalli, J M; Castellano, G

    2016-12-01

    The spatial resolution of the electron backscatter diffraction signal is explored by Monte Carlo simulation for the sigma phase in steel at a typical instrumental set-up. In order to estimate the active volume corresponding to the diffracted electrons, the fraction of the backscattered electrons contributing to the diffraction signal was inferred by extrapolating the Kikuchi pattern contrast measured by other authors, as a function of the diffracted electron energy. In the resulting estimation, the contribution of the intrinsic incident beam size and the software capability to deconvolve patterns were included. A strong influence of the beam size on the lateral resolution was observed, resulting in 20nm for the aperture considered. For longitudinal and depth directions the resolutions obtained were 75nm and 16nm, respectively. The reliability of this last result is discussed in terms of the survey of the last large-angle deflection undergone by the backscattered electrons involved in the diffraction process. Bearing in mind the mean transversal resolution found, it was possible to detect small area grains of sigma phase by EBSD measurements, for a stabilized austenitic AISI 347 stainless steel under heat treatments, simulating post welding (40h at 600°C) and aging (284h at 484°C) effects-as usually occurring in nuclear reactor pressure vessels. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. An exploratory analysis for Lean and Six Sigma implementation in hospitals: Together is better?

    PubMed

    Lee, Jung Young; McFadden, Kathleen L; Gowen, Charles R

    2016-12-22

    Despite the increasing interest for Lean and Six Sigma implementations in hospitals, there has been little empirical evidence that goes beyond descriptive case studies to address the current status and the effectiveness of the implementations. The aim of this study was to explore existing patterns of Lean and Six Sigma implementation in U.S. hospitals and compare the performance of the different patterns. We collected data from 215 U.S. hospitals via a survey that includes measurement items developed from related literature. Using the cross-sectional data, we conducted a cluster analysis, followed by t tests, chi-square tests, and regression analyses for cluster verification. The cluster analysis identifies two clusters, a Moderate Six Sigma group and a Lean Six Sigma group. Results show that the Lean Six Sigma group outperforms the Moderate Six Sigma group across many performance dimensions: responsiveness capability, patient safety, and possibly cost saving. In addition, the Lean Six Sigma group tends to be composed of larger, private teaching hospitals located in more urban areas, and they employ more resources for quality improvement. Our research contributes to the quality management literature by supporting the possible complementary relationship between Lean and Six Sigma in hospitals. Our study encourages practitioners and managers to pay more attention to Lean implementation. Although Lean seems to be conducted in a limited fashion in many hospitals, it should be expanded and combined with Six Sigma for better results.

  8. Six Sigma Quality Management System and Design of Risk-based Statistical Quality Control.

    PubMed

    Westgard, James O; Westgard, Sten A

    2017-03-01

    Six sigma concepts provide a quality management system (QMS) with many useful tools for managing quality in medical laboratories. This Six Sigma QMS is driven by the quality required for the intended use of a test. The most useful form for this quality requirement is the allowable total error. Calculation of a sigma-metric provides the best predictor of risk for an analytical examination process, as well as a design parameter for selecting the statistical quality control (SQC) procedure necessary to detect medically important errors. Simple point estimates of sigma at medical decision concentrations are sufficient for laboratory applications. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Under the knife: a national survey of six sigma programs in US healthcare organizations.

    PubMed

    Feng, Qianmei; Manuel, Chris M

    2008-01-01

    Medical and policy literature reports many six sigma applications at specific healthcare organizations. However, there is a lack of studies that investigate the broader status of six sigma in US healthcare systems. The purpose of this paper is to present the results from a national survey of six sigma programs in US healthcare organizations. Through the design, distribution, and analysis of a nationwide survey, this paper assesses the implementation of six sigma in healthcare facilities. Two sets of surveys were designed based on whether an organization has adopted six sigma or not. Findings from this paper indicate the common six sigma projects implemented in healthcare organizations, typical implementation durations, cost benefits, and major barriers in implementation, and so on. This paper is limited by the low-response rate owing to time and budget constraints. Through the dissemination of this paper, it is hoped that more organizations will become interested in this subject and participate in future studies. This work is the first study to investigate the implementation status of six sigma in US healthcare systems. It will share experiences amongst six sigma institutions and promote its application in many institutions. The findings will provide instructive information to six sigma practitioners and researchers, and particularly to health care management.

  10. Synthesis and pharmacological evaluation of indole-based sigma receptor ligands

    PubMed Central

    Mésangeau, Christophe; Amata, Emanuele; Alsharif, Walid; Seminerio, Michael J.; Robson, Matthew J.; Matsumoto, Rae R.; Poupaert, Jacques H.; McCurdy, Christopher R.

    2011-01-01

    A series of novel indole-based analogues were prepared and their affinities for sigma receptors were determined using in vitro radioligand binding assays. The results of this study identified several compounds with nanomolar sigma-2 affinity and significant selectivity over sigma-1 receptors. In particular, 2-(4-(3-(4-fluorophenyl)indol-1-yl)butyl)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline (9f) was found to display high affinity at sigma-2 receptors with good selectivity (σ-1/σ-2 = 395). The pharmacological binding profile for this compound was established with other relevant nonsigma sites. PMID:21899931

  11. PURIFICATION AND CHARACTERIZATION OF THE GUINEA PIG SIGMA-1 RECEPTOR FUNCTIONALLY EXPRESSED IN Escherichia coli

    PubMed Central

    Ramachandran, Subramaniam; Lu, Hongliang; Prabhu, Usha; Ruoho, Arnold E.

    2007-01-01

    Sigma receptors once considered as a class of opioid receptors are now regarded as unique orphan receptors, distinguished by the ability to bind various pharmacological agents such as the progesterone (steroid), haloperidol (antipsychotic), and drugs of abuse such as cocaine and methamphetamine. The sigma-1 receptor is a 223 amino acid protein, proposed to have two transmembrane segments. We have developed a scheme for the purification of the guinea pig sigma-1 receptor following overexpression in Escherichia coli as a maltose binding protein (MBP) fusion and extraction with TritonX-100. Affinity chromatography using an amylose column and Ni2+ affinity column was used to purify the sigma-1 receptor. The sigma-1 receptor purified by this method is a 26 kDa polypeptide as assessed by SDS-PAGE, binds sigma ligands with high affinity and can be specifically photoaffinity labeled with the sigma-1 receptor photoprobe, [125I]-iodoazidococaine. Ligand binding using [3H]-(+)-pentazocine indicated that approximately half of the purified protein in Triton X-100 bound to radioligand. The MBP-sigma-1 receptor and the sigma-1 receptor in 0.5 % triton were maximally stable for approximately two weeks at −20°C in buffer containing 30 % glycerol. PMID:16962337

  12. Purification and characterization of the guinea pig sigma-1 receptor functionally expressed in Escherichia coli.

    PubMed

    Ramachandran, Subramaniam; Lu, Hongliang; Prabhu, Usha; Ruoho, Arnold E

    2007-02-01

    Sigma receptors once considered as a class of opioid receptors are now regarded as unique orphan receptors, distinguished by the ability to bind various pharmacological agents such as the progesterone (steroid), haloperidol (anti-psychotic), and drugs of abuse such as cocaine and methamphetamine. The sigma-1 receptor is a 223 amino acid protein, proposed to have two transmembrane segments. We have developed a scheme for the purification of the guinea pig sigma-1 receptor following overexpression in Escherichia coli as a maltose binding protein (MBP) fusion and extraction with Triton X-100. Affinity chromatography using an amylose column and Ni2+ affinity column was used to purify the sigma-1 receptor. The sigma-1 receptor purified by this method is a 26 kDa polypeptide as assessed by SDS-PAGE, binds sigma ligands with high affinity and can be specifically photoaffinity labeled with the sigma-1 receptor photoprobe, [125I]-iodoazidococaine. Ligand binding using [3H]-(+)-pentazocine indicated that approximately half of the purified protein in Triton X-100 bound to radioligand. The MBP-sigma-1 receptor and the sigma-1 receptor in 0.5% triton were maximally stable for approximately two weeks at -20 degrees C in buffer containing 30% glycerol.

  13. 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.

  14. 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

  15. 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.

  16. sigma, a repetitive element found adjacent to tRNA genes of yeast.

    PubMed Central

    del Rey, F J; Donahue, T F; Fink, G R

    1982-01-01

    sigma is a DNA element of about 340 base pairs (bp) that is repeated many times in the yeast genome. The element has 8-bp inverted repeats at its ends and is flanked by 5-bp direct repeats. The 5-bp repeats are different for each sigma and have no homology with the ends of the sigma sequence. sigma is located 16 or 18 bp from the 5' end of several tRNA genes. Southern analysis of different yeast strains shows that the pattern of hybridization is different even for closely related strains. Images PMID:6287468

  17. The structure of alkali metal derivatives of azoles: N-sigma versus pi structures.

    PubMed

    Blanco, Fernando; Alkorta, Ibon; Elguero, Jose

    2008-08-21

    High level ab initio calculations have been used to study the relative stability of N-sigma and pi configurations of the neutral alkaline derivatives of azoles. The N-sigma structure is the one normally expected for nonionized azolate salts. However, the results show that in the case of the pyrrole and imidazole the pi configuration is more stable than the N-sigma one. The preference of the N-sigma vs pi configurations is related to the presence or the absence of two contiguous nitrogen atoms in the azole ring. A search in the CSD shows that some pyrrolate and imidazolate salts exist in solid phase in the pi configuration.

  18. Massive Compact Stars as Quark Stars

    NASA Astrophysics Data System (ADS)

    Rodrigues, Hilário; Barbosa Duarte, Sérgio; de Oliveira, José Carlos T.

    2011-03-01

    High-mass compact stars have been reported recently in the literature, providing strong constraints on the properties of the ultra dense matter beyond the saturation nuclear density. In view of these results, the calculations of quark star or hybrid star equilibrium structure must be compatible with the provided observational data. But since the equations of state used in describing quark matter are in general too soft in comparison with the equation of states used to describe the hadronic or nuclear matter, the calculated quark star models presented in the literature are in general not suitable to explain the stability of highly-compact massive objects. In this work, we present the calculations of a spherically symmetric quark star structure by using an equation of state that takes into account the superconducting color-flavor locked phase of the strange quark matter. In addition, some fundamental aspects of QCD (asymptotic freedom and confinement) are considered by means of a phenomenological description of the deconfined quark phase, the density-dependent quark mass model. The quark matter behavior introduced by this model stiffens the corresponding equation of state. We thus investigate the influence of this model on the mass-radius diagram of quark stars. We obtain massive quark stars due to the stiffness of the equation of state, when a reasonable parameterization of the color superconducting gap is used. Models of quark stars enveloped by a nucleonic crust composed of a nuclear lattice embedded in an electron gas, with nuclei close to neutron drip line, are also discussed.

  19. [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.

  20. Star Clusters within FIRE

    NASA Astrophysics Data System (ADS)

    Perez, Adrianna; Moreno, Jorge; Naiman, Jill; Ramirez-Ruiz, Enrico; Hopkins, Philip F.

    2017-01-01

    In this work, we analyze the environments surrounding star clusters of simulated merging galaxies. Our framework employs Feedback In Realistic Environments (FIRE) model (Hopkins et al., 2014). The FIRE project is a high resolution cosmological simulation that resolves star forming regions and incorporates stellar feedback in a physically realistic way. The project focuses on analyzing the properties of the star clusters formed in merging galaxies. The locations of these star clusters are identified with astrodendro.py, a publicly available dendrogram algorithm. Once star cluster properties are extracted, they will be used to create a sub-grid (smaller than the resolution scale of FIRE) of gas confinement in these clusters. Then, we can examine how the star clusters interact with these available gas reservoirs (either by accreting this mass or blowing it out via feedback), which will determine many properties of the cluster (star formation history, compact object accretion, etc). These simulations will further our understanding of star formation within stellar clusters during galaxy evolution. In the future, we aim to enhance sub-grid prescriptions for feedback specific to processes within star clusters; such as, interaction with stellar winds and gas accretion onto black holes and neutron stars.

  1. 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.

  2. 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.

  3. Ab initio studies of low-lying 3Sigma(-), 3Pi, and 5Sigma(-) states of NH. I - Potential curves and dipole moment functions

    NASA Technical Reports Server (NTRS)

    Goldfield, Evelyn M.; Kirby, Kate P.

    1987-01-01

    Configuration interaction wave functions, potential energy curves, and dipole moment functions have been calculated for the four lowest 3Sigma(-) and the three lowest 3Pi states and 5Sigma(-) states of NH. The electronic wave functions were constructed to give a balanced description of valence-Rydberg interactions. Two repulsive states have been identified as important photodissociation pathways. Spectroscopic constants are presented for the bound states, and results are compared to other theoretical and experimental work. The possible predissociation of the A 3Pi state by the 1 5Sigma(-) state is discussed.

  4. Baculovirus surface display of sigmaC and sigmaB proteins of avian reovirus and immunogenicity of the displayed proteins in a mouse model.

    PubMed

    Lin, Yueh H; Lee, Long H; Shih, Wen L; Hu, Yu C; Liu, Hung J

    2008-11-25

    Avian reovirus (ARV), an important pathogen in poultry, causes arthritis, chronic respiratory disease, and malabsorption syndrome that cause considerable economic losses to the poultry industry. In present study, we have succeeded in construction of a universal baculovirus surface display system (UBSDS) that can display different foreign proteins on the envelope of baculovirus. Sequences encoding the signal peptide (SS), transmembrane domain (TM), and cytoplasmic domain (CTD) derived from the gp64 protein of baculovirus and histidine tag, respectively were inserted into the pBacCE vector. Four restriction enzyme sites between the histidine tag and gp64 transmembrane domain were established for expression of different foreign proteins. The transmembrane domain and CTD of gp64 in the platform were designed in order to improve stability and quantity of foreign proteins on the envelope of baculovirus. The sigmaC and sigmaB proteins of ARV are known to elicit neutralizing antibodies against ARV. The UBSDS was therefore used to express sigmaC and sigmaB proteins on the envelope of baculovirus. Two recombinant baculoviruses BacSC-sigmaC and BacSC-sigmaB have been successfully constructed. After infection, both His6-tagged recombinant sigmaC (rsigmaC) and sigmaB (rsigmaB) proteins were displayed on the envelope of recombinant baculoviruses and the recombinant viral proteins were anchored on the plasma membrane of Sf-9 cells, as revealed by immunofluorescence staining (IFS) and confocal microscopy. The antigenicity of rsigmaC and rsigmaB proteins was demonstrated by Western blotting assay. Immunogold electron microscopy demonstrated that both recombinant viruses displayed rsigmaC and rsigmaB proteins on the viral surface. Immunization of BALB/c mice with recombinant viruses, demonstrated that serum from the BacSC-sigmaC and BacSC-sigmaB treated models had significant higher levels of virus neutralization activities than the control groups. This demonstrates that the

  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 microlensing - The effect of random motion of individual stars in the lensing galaxy

    NASA Technical Reports Server (NTRS)

    Kundic, Tomislav; Wambsganss, Joachim

    1993-01-01

    We investigate the influence of random motion of individual stars in the lensing galaxy on the light curve of a gravitationally lensed background quasar. We compare this with the effects of the transverse motion of the galaxy. We find that three-dimensional random motion of stars with a velocity dispersion sigma in each dimension is more effective in producing 'peaks' in a microlensed light curve by a factor a about 1.3 than motion of the galaxy with a transverse velocity v(t) = sigma. This effectiveness parameter a seems to depend only weakly on the surface mass density. With an assumed transverse velocity of v(t) = 600 km/s of the galaxy lensing the QSO 2237+0305 and a measured velocity dispersion of sigma = 215 km/s, the expected rate of maxima in the light curves calculated for bulk motion alone has to be increased by about 10 percent due to the random motion of stars. As a consequence, the average time interval Delta t between two high-magnification events is smaller than the time interval Delta(t) bulk, calculated for bulk motion alone, Delta t about 0.9 Delta(t) bulk.

  7. Application of sigma metrics for the assessment of quality assurance in clinical biochemistry laboratory in India: a pilot study.

    PubMed

    Singh, Bhawna; Goswami, Binita; Gupta, Vinod Kumar; Chawla, Ranjna; Mallika, Venkatesan

    2011-04-01

    Ensuring quality of laboratory services is the need of the hour in the field of health care. Keeping in mind the revolution ushered by six sigma concept in corporate world, health care sector may reap the benefits of the same. Six sigma provides a general methodology to describe performance on sigma scale. We aimed to gauge our laboratory performance by sigma metrics. Internal quality control (QC) data was analyzed retrospectively over a period of 6 months from July 2009 to December 2009. Laboratory mean, standard deviation and coefficient of variation were calculated for all the parameters. Sigma was calculated for both the levels of internal QC. Satisfactory sigma values (>6) were elicited for creatinine, triglycerides, SGOT, CPK-Total and Amylase. Blood urea performed poorly on the sigma scale with sigma <3. The findings of our exercise emphasize the need for detailed evaluation and adoption of ameliorative measures in order to effectuate six sigma standards for all the analytical processes.

  8. 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.

  9. 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. © 2016 Wiley Periodicals, Inc.

  10. 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

  11. 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.

  12. Equilibrium Star Cluster Formation

    NASA Astrophysics Data System (ADS)

    Tan, Jonathan C.; Krumholz, Mark R.; McKee, Christopher F.

    2006-04-01

    We argue that rich star clusters take at least several local dynamical times to form and so are quasi-equilibrium structures during their assembly. Observations supporting this conclusion include morphologies of star-forming clumps, momentum flux of protostellar outflows from forming clusters, age spreads of stars in the Orion Nebula cluster (ONC) and other clusters, and the age of a dynamical ejection event from the ONC. We show that these long formation timescales are consistent with the expected star formation rate in turbulent gas, as recently evaluated by Krumholz & McKee. Finally, we discuss the implications of these timescales for star formation efficiencies, the disruption of gas by stellar feedback, mass segregation of stars, and the longevity of turbulence in molecular clumps.

  13. Age-Defying Star

    NASA Image and Video Library

    2016-08-29

    An age-defying star called IRAS 19312+1950 exhibits features characteristic of a very young star and a very old star. The object stands out as extremely bright inside a large, chemically rich cloud of material, as shown in this image from NASA's Spitzer Space Telescope. IRAS 19312+1950 is the bright red star in the center of this image. A NASA-led team of scientists thinks the star -- which is about 10 times as massive as our sun and emits about 20,000 times as much energy -- is a newly forming protostar. That was a big surprise, because the region had not been known as a stellar nursery before. But the presence of a nearby interstellar bubble, which indicates the presence of a recently formed massive star, also supports this idea. http://photojournal.jpl.nasa.gov/catalog/PIA20914

  14. 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.

  15. Coupling of the X {sup 1}{sigma}{sup +} and a {sup 3}{sigma}{sup +} states of KRb

    SciTech Connect

    Pashov, A.; Docenko, O.; Tamanis, M.; Ferber, R.; Knoeckel, H.; Tiemann, E.

    2007-08-15

    A comprehensive study of the electronic states at the 4s+5s asymptote in KRb is presented. Abundant spectroscopic data on the a {sup 3}{sigma}{sup +} state were collected by Fourier-transform spectroscopy, which allows one to determine an accurate experimental potential energy curve up to 14.8 A. The existing data set [C. Amiot et al., J. Chem. Phys. 112, 7068 (2000)] on the ground state X {sup 1}{sigma}{sup +} was extended by several additional levels lying close to the atomic asymptote. In a coupled channels fitting routine complete molecular potentials for both electronic states were fitted. Along with the line frequencies of the molecular transitions, recently published positions of Feshbach resonances in {sup 40}K and {sup 87}Rb mixtures [F. Ferlaino et al., Phys. Rev. A 74, 039903 (2006)] were included in the fit. This makes the derived potential curves capable for an accurate description of observed cold collision features so far. Predictions of scattering lengths and Feshbach resonances in other isotopic combinations are reported.

  16. 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.

  17. SIRTF and star formation

    NASA Technical Reports Server (NTRS)

    Shu, Frank H.

    1988-01-01

    Four problems in the field of star formation that can be attacked to advantage with SIRTF are discussed: (1) the patterns of star formation in spiral galaxies, (2) the physical mechanism for bimodal star formation, (3) the nature of bipolar outflows from young stellar objects, and (4) the birth of brown dwarfs. In each case, SIRTF can provide the crucial combination of high angular resolution with great sensitivity over a broad range of wavelengths that is needed to address the relevant issues.

  18. Strange nonchaotic stars.

    PubMed

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

    2015-02-06

    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.

  19. The Theatre of stars

    NASA Astrophysics Data System (ADS)

    Cavedon, M.; Peri, F.

    Planetariums are special instruments in education and didactics of Astronomy and Astrophysics. Since 1930 the Planetarium of Milan, the most important planetarium in Italy, has played a fundamental role in outreach to the public. Italian tradition always preferred didactics in ``live'' lessons. Now technology expands the potential of the star projector and the theatre of stars is a real window on the universe, where you can travel among the stars and galaxies, to reach the boundaries of space and time.

  20. Nagyszombat and the stars

    NASA Astrophysics Data System (ADS)

    Zsoldos, E.

    Péter Pázmány, founder of the University of Nagyszombat, considered stars in terms inherited from medieval times. The theses, connected to the university graduation, soon left this definition, and imagined stars as made from sublunar elements. The 1753 decree of the Empress Maria Theresia ordered university professors to publish textbooks. These textbooks, together with the theses showed a definite improvement, defining stars according to contemporary knowledge.

  1. Sigma-1 receptors regulate activity-induced spinal sensitization and neuropathic pain after peripheral nerve injury.

    PubMed

    de la Puente, Beatriz; Nadal, Xavier; Portillo-Salido, Enrique; Sánchez-Arroyos, Ricard; Ovalle, Sergio; Palacios, Gabriel; Muro, Asunción; Romero, Luz; Entrena, José Manuel; Baeyens, José Manuel; López-García, José Antonio; Maldonado, Rafael; Zamanillo, Daniel; Vela, José Miguel

    2009-10-01

    Sigma-1 receptor (sigma(1)R) is expressed in key CNS areas involved in nociceptive processing but only limited information is available about its functional role. In the present study we investigated the relevance of sigma(1)R in modulating nerve injury-evoked pain. For this purpose, wild-type mice and mice lacking the sigma(1)R gene were exposed to partial sciatic nerve ligation and neuropathic pain-related behaviors were investigated. To explore underlying mechanisms, spinal processing of repetitive nociceptive stimulation and expression of extracellular signal-regulated kinase (ERK) were also investigated. Sensitivity to noxious heat of homozygous sigma(1)R knockout mice did not differ from wild-type mice. Baseline values obtained in sigma(1)R knockout mice before nerve injury in the plantar, cold-plate and von Frey tests were also indistinguishable from those obtained in wild-type mice. However, cold and mechanical allodynia did not develop in sigma(1)R null mice exposed to partial sciatic nerve injury. Using isolated spinal cords we found that mice lacking sigma(1)R showed reduced wind-up responses respect to wild-type mice, as evidenced by a reduced number of action potentials induced by trains of C-fiber intensity stimuli. In addition, in contrast to wild-type mice, sigma(1)R knockout mice did not show increased phosphorylation of ERK in the spinal cord after sciatic nerve injury. Both wind-up and ERK activation have been related to mechanisms of spinal cord sensitization. Our findings identify sigma(1)R as a constituent of the mechanisms modulating activity-induced sensitization in pain pathways and point to sigma(1)R as a new potential target for drugs designed to alleviate neuropathic pain.

  2. Sigma-1 receptor agonists as therapeutic drugs for cognitive impairment in neuropsychiatric diseases.

    PubMed

    Niitsu, Tomihisa; Iyo, Masaomi; Hashimoto, Kenji

    2012-01-01

    Cognitive impairment is a core feature of patients with neuropsychiatric diseases such as schizophrenia and psychotic depression. The drugs currently used to treat cognitive impairment have significant limitations, ensuring that the search for more effective therapies remains active. Endoplasmic reticulum protein sigma-1 receptors are unique binding sites in the brain that exert a potent effect on multiple neurotransmitter systems. Accumulating evidence suggests that sigma-1 receptors play a role in both the pathophysiology of neuropsychiatric diseases, and the mechanistic action of some therapeutic drugs, such as the selective serotonin reuptake inhibitors (SSRIs), donepezil and neurosteroids. Among SSRIs, fluvoxamine, a potent sigma-1 receptor agonist, has the highest affinity at sigma-1 receptors. Sigma-1 receptor agonists greatly potentiate nerve-growth factor (NGF)-induced neurite outgrowth in PC12 cells, an effect that is antagonized by treatment with the selective sigma-1 receptor antagonist NE-100. Furthermore, phencyclidine (PCP)-induced cognitive impairment, associated with animal models of schizophrenia is significantly improved by sub-chronic administration of sigma-1 receptor agonists such as fluvoxamine, SA4503 (cutamesine) and donepezil. This effect is antagonized by co-administration of NE-100. A positron emission tomography (PET) study using the specific sigma-1 receptor ligand [11C]SA4503 demonstrates that fluvoxamine and donepezil bind to sigma-1 receptors in the healthy human brain. In clinical studies, some sigma-1 receptor agonists, including fluvoxamine, donepezil and neurosteroids, improve cognitive impairment and clinical symptoms in neuropsychiatric diseases. In this article, we review the recent findings on sigma-1 receptor agonists as potential therapeutic drugs for the treatment of cognitive impairment in schizophrenia and psychotic depression.

  3. Characterization of Bax-sigma, a cell death-inducing isoform of Bax.

    PubMed

    Schmitt, E; Paquet, C; Beauchemin, M; Dever-Bertrand, J; Bertrand, R

    2000-04-21

    The Ced-9/Bcl-like family of genes codes for proteins that have antiapoptotic and proapoptotic activity. Several Bax isoproteins have been detected by 2-D gel electrophoresis, and a novel human member, designated as Bax-sigma, has been identified and cloned from human cancer promyelocytic cells. Bax-sigma contains BH-3, BH-1, and BH-2 domains, putative alpha-5 and alpha-6 helices, and the carboxy-terminal hydrophobic transmembrane domain but lacks amino acids 159 to 171 compared to Bax-alpha. mRNA expression analysis by reverse transcription-polymerase chain reaction and RNase protection assays have revealed that Bax-sigma is expressed in a variety of human cancer cell lines and normal tissues. To investigate the potential role of Bax-sigma in apoptosis, first its effects were compared to those of Bax-alpha by transient expression in human B lymphoma Namalwa cells. Both Bax-sigma and Bax-alpha promoted apoptosis, as detected by DNA fragmentation and morphological analysis by electron microscopy. The apoptosis induced by Bax-sigma and Bax-alpha was correlated with their expression, cytochrome c release, and caspase activation. In a yeast two-hybrid system, Bax-sigma interacted with several Ced-9/Bcl family members but had no affinity for the human Egl-1 homologs Bik and Bad and the Ced-4 homolog Apaf-1. In human cells, Bax-sigma function was counteracted by Bcl-xL overexpression, and co-immunoprecipitation experiments indicated that Bax-sigma was associated with Bcl-xL. Furthermore, Bax-sigma overexpression increased cell death induced by various concentrations of genotoxic agents with the most pronounced effect occurring at low camptothecin and vinblastine dose levels. Our results suggest that Bax-sigma, a novel variant of Bax, encodes a protein with a proapoptotic effect and mode of action similar to those of Bax-alpha.

  4. Sigma-1 receptors modulate neonatal Nav1.5 ion channels in breast cancer cell lines.

    PubMed

    Aydar, Ebru; Stratton, Dan; Fraser, Scott P; Djamgoz, Mustafa B A; Palmer, Christopher

    2016-10-01

    The main aim of this study was to investigate a possible functional connection between sigma-1 receptors and voltage-gated sodium channels (VGSCs) in human breast cancer cells. The hypothesis was that sigma-1 drugs could alter the metastatic properties of breast cancer cells via the VGSC. Evidence was found for expression of sigma-1 receptor and neonatal Nav1.5 (nNav1.5) expression in both MDA-MB-231 and MDA-MB-468 cells. Sigma-1 drugs (SKF10047 and dimethyltryptamine) did not affect cell proliferation or migration but significantly reduced adhesion to the substrate. Silencing sigma-1 receptor expression by siRNA similarly reduced the adhesion. Blocking nNav1.5 activity with a polyclonal antibody (NESOpAb) targeting an extracellular region of nNav1.5 also reduced the adhesion in both cell lines. Importantly, the results of combined treatments with NESOpAb and a sigma-1 drug or sigma-1 siRNA suggested that both treatments targeted the same mechanism. The possibility was tested, therefore, that the sigma-1 receptor and the nNav1.5 channel formed a physical, functional complex. This suggestion was supported by the results of co-immunoprecipitation experiments. Furthermore, application of sigma-1 drugs to the cells reduced the surface expression of nNav1.5 protein, which could explain how sigma-1 receptor activation could alter the metastatic behaviour of breast cancer cells. Overall, these results are consistent with the idea of a sigma-1 protein behaving like either a "chaperone" or a regulatory subunit associated with nNav1.5.

  5. 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.

  6. 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.

  7. Strangeon and Strangeon Star

    NASA Astrophysics Data System (ADS)

    Xiaoyu, Lai; Renxin, Xu

    2017-06-01

    The nature of pulsar-like compact stars is essentially a central question of the fundamental strong interaction (explained in quantum chromo-dynamics) at low energy scale, the solution of which still remains a challenge though tremendous efforts have been tried. This kind of compact objects could actually be strange quark stars if strange quark matter in bulk may constitute the true ground state of the strong-interaction matter rather than 56Fe (the so-called Witten’s conjecture). From astrophysical points of view, however, it is proposed that strange cluster matter could be absolutely stable and thus those compact stars could be strange cluster stars in fact. This proposal could be regarded as a general Witten’s conjecture: strange matter in bulk could be absolutely stable, in which quarks are either free (for strange quark matter) or localized (for strange cluster matter). Strange cluster with three-light-flavor symmetry is renamed strangeon, being coined by combining “strange nucleon” for the sake of simplicity. A strangeon star can then be thought as a 3-flavored gigantic nucleus, and strangeons are its constituent as an analogy of nucleons which are the constituent of a normal (micro) nucleus. The observational consequences of strangeon stars show that different manifestations of pulsarlike compact stars could be understood in the regime of strangeon stars, and we are expecting more evidence for strangeon star by advanced facilities (e.g., FAST, SKA, and eXTP).

  8. Delta Scuti stars: Theory

    NASA Technical Reports Server (NTRS)

    Guzik, J. A.

    1998-01-01

    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.

  9. Massive soliton stars

    NASA Astrophysics Data System (ADS)

    Chiu, Hong-Yee

    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.

  10. 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.

  11. 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.

  12. 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.

  13. Ecospheres around binary stars

    NASA Astrophysics Data System (ADS)

    Deka, B.

    2011-01-01

    Scientific investigations concerning ecospheres of other stars are very important for understanding the posibilities of existence and evolution of extraterrestrial life. In several last years astronomers discovered hundreds of extrasolar planets. Identification of stars with ecospheres is the first step in selecting those planets which could be inhabited. Usually an ecosphere of a single star is considered but it may also exist in planetary systems with two suns. This possibility is very promising in search for life on other planets as more that 60 % of stars reside in binary or multiple systems.

  14. 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.

  15. Charged Proca stars

    NASA Astrophysics Data System (ADS)

    Landea, Ignacio Salazar; García, Federico

    2016-11-01

    In this paper, we study gauged solutions associated with a massive vector field representing a spin-1 condensate, namely, the Proca field. We focus on regular spherically symmetric solutions which we construct either using a self-interaction potential or general relativity in order to glue the solutions together. We start generating nongravitating solutions—so-called Proca Q -balls and charged Proca Q -balls. Then we turn on backreaction on the metric, allowing gravity to hold together the Proca condensate, to study the so-called Proca stars, charged Proca stars, Proca Q -stars, and charged Proca Q -stars.

  16. Delta Scuti stars: Theory

    NASA Technical Reports Server (NTRS)

    Guzik, J. A.

    1998-01-01

    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.

  17. 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)

  18. Dipole moments and transition probabilities of the a 3Sigma(+)g - b 3Sigma(+)u system of molecular hydrogen

    NASA Technical Reports Server (NTRS)

    Guberman, S.; Dalgarno, A.; Posen, A.; Kwok, T. L.

    1986-01-01

    Multiconfiguration variational calculations of the electronic wave functions of the a 3Sigma(+)g and b 3Sigma(+)u states of molecular hydrogen are presented, and the electric dipole transition moment between them (of interest in connection with stellar atmospheres and the UV spectrum of the Jovian planets) is obtained. The dipole moment is used to calculate the probabilities of radiative transitions from the discrete vibrational levels of the a 3Sigma(+)g state to the vibrational continuum of the repulsive b 3Sigma(+)u state as functions of the wavelength of the emitted photons. The total transition probabilities and radiative lifetimes of the levels v prime = 0-20 are presented.

  19. 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.

  20. A comparison of methods for computing the sigma-coordinate pressure gradient force for flow over sloped terrain in a hybrid theta-sigma model

    NASA Technical Reports Server (NTRS)

    Johnson, D. R.; Uccellini, L. W.

    1983-01-01

    In connection with the employment of the sigma coordinates introduced by Phillips (1957), problems can arise regarding an accurate finite-difference computation of the pressure gradient force. Over steeply sloped terrain, the calculation of the sigma-coordinate pressure gradient force involves computing the difference between two large terms of opposite sign which results in large truncation error. To reduce the truncation error, several finite-difference methods have been designed and implemented. The present investigation has the objective to provide another method of computing the sigma-coordinate pressure gradient force. Phillips' method is applied for the elimination of a hydrostatic component to a flux formulation. The new technique is compared with four other methods for computing the pressure gradient force. The work is motivated by the desire to use an isentropic and sigma-coordinate hybrid model for experiments designed to study flow near mountainous terrain.