Rotation in moderate-mass pre-main-sequence radiative track G stars

International Nuclear Information System (INIS)

Mcnamara, B.

1990-01-01

Recent studies suggest that the observed high-mass radiative track velocity histograms for pre-main-sequence stars differ significantly. In the Vogel and Kuhi (1981) study, these stars were found to possess a rather broad distribution of rotational velocities with a moderate peak at low velocities. In contrast, Smith et al. (1983), found a very sharply peaked distribution located at low values of v sin i. The difference in these velocity distributions is shown to be due to inadequate allowance for field stars in the Smith, et al., work. Once these stars are removed, the high-mass velocity distributions of the two regions are remarkably similar. This result suggests that a unique velocity distribution might be used in modeling very young stars. Assuming that the Orion Ic proto-F stars continue to contract in a homologous fashion, their average current rotational velocity is in agreement with that expected for zero-age main sequence F stars. 27 refs

YSOVAR: SIX PRE-MAIN-SEQUENCE ECLIPSING BINARIES IN THE ORION NEBULA CLUSTER

Energy Technology Data Exchange (ETDEWEB)

Morales-Calderon, M.; Stauffer, J. R.; Rebull, L. M. [Spitzer Science Center, California Institute of Technology, 1200 E California Blvd., Pasadena, CA 91125 (United States); Stassun, K. G. [Physics and Astronomy Department, Vanderbilt University, 1807 Station B, Nashville, TN 37235 (United States); Vrba, F. J. [U. S. Naval Observatory, Flagstaff Station, 10391 W. Naval Observatory Road, Flagstaff, AZ 86001-8521 (United States); Prato, L. [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States); Hillenbrand, L. A.; Carpenter, J. M. [Astronomy Department, California Institute of Technology, 1200 E California Blvd., Pasadena, CA 91125 (United States); Terebey, S.; Angione, J. [Department of Physics and Astronomy, California State University at Los Angeles, Los Angeles, CA 90032 (United States); Covey, K. R. [Department of Astronomy, Cornell University, 226 Space Sciences Building, Ithaca, NY 14853 (United States); Terndrup, D. M. [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Gutermuth, R. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Song, I. [Physics and Astronomy Department, University of Georgia, Athens, GA 30602-2451 (United States); Plavchan, P. [NASA Exoplanet Science Institute, California Institute of Technology, Pasadena, CA 91125 (United States); Marchis, F. [SETI Institute, Carl Sagan Center, 189 N San Bernado Av, Mountain View, CA 94043 (United States); Garcia, E. V. [Department of Physics, Fisk University, 1000 17th Ave. N, Nashville, TN 37208 (United States); Margheim, S. [Gemini Observatory, Southern Operations Center, Casilla 603, La Serena (Chile); Luhman, K. L. [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States); Irwin, J. M., E-mail: mariamc@cab.inta-csic.es [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States)

2012-07-10

Eclipsing binaries (EBs) provide critical laboratories for empirically testing predictions of theoretical models of stellar structure and evolution. Pre-main-sequence (PMS) EBs are particularly valuable, both due to their rarity and the highly dynamic nature of PMS evolution, such that a dense grid of PMS EBs is required to properly calibrate theoretical PMS models. Analyzing multi-epoch, multi-color light curves for {approx}2400 candidate Orion Nebula Cluster (ONC) members from our Warm Spitzer Exploration Science Program YSOVAR, we have identified 12 stars whose light curves show eclipse features. Four of these 12 EBs are previously known. Supplementing our light curves with follow-up optical and near-infrared spectroscopy, we establish two of the candidates as likely field EBs lying behind the ONC. We confirm the remaining six candidate systems, however, as newly identified ONC PMS EBs. These systems increase the number of known PMS EBs by over 50% and include the highest mass ({theta}{sup 1} Ori E, for which we provide a complete set of well-determined parameters including component masses of 2.807 and 2.797 M{sub Sun }) and longest-period (ISOY J053505.71-052354.1, P {approx} 20 days) PMS EBs currently known. In two cases ({theta}{sup 1} Ori E and ISOY J053526.88-044730.7), enough photometric and spectroscopic data exist to attempt an orbit solution and derive the system parameters. For the remaining systems, we combine our data with literature information to provide a preliminary characterization sufficient to guide follow-up investigations of these rare, benchmark systems.

YSOVAR: SIX PRE-MAIN-SEQUENCE ECLIPSING BINARIES IN THE ORION NEBULA CLUSTER

International Nuclear Information System (INIS)

Morales-Calderón, M.; Stauffer, J. R.; Rebull, L. M.; Stassun, K. G.; Vrba, F. J.; Prato, L.; Hillenbrand, L. A.; Carpenter, J. M.; Terebey, S.; Angione, J.; Covey, K. R.; Terndrup, D. M.; Gutermuth, R.; Song, I.; Plavchan, P.; Marchis, F.; García, E. V.; Margheim, S.; Luhman, K. L.; Irwin, J. M.

2012-01-01

Eclipsing binaries (EBs) provide critical laboratories for empirically testing predictions of theoretical models of stellar structure and evolution. Pre-main-sequence (PMS) EBs are particularly valuable, both due to their rarity and the highly dynamic nature of PMS evolution, such that a dense grid of PMS EBs is required to properly calibrate theoretical PMS models. Analyzing multi-epoch, multi-color light curves for ∼2400 candidate Orion Nebula Cluster (ONC) members from our Warm Spitzer Exploration Science Program YSOVAR, we have identified 12 stars whose light curves show eclipse features. Four of these 12 EBs are previously known. Supplementing our light curves with follow-up optical and near-infrared spectroscopy, we establish two of the candidates as likely field EBs lying behind the ONC. We confirm the remaining six candidate systems, however, as newly identified ONC PMS EBs. These systems increase the number of known PMS EBs by over 50% and include the highest mass (θ 1 Ori E, for which we provide a complete set of well-determined parameters including component masses of 2.807 and 2.797 M ☉ ) and longest-period (ISOY J053505.71–052354.1, P ∼ 20 days) PMS EBs currently known. In two cases (θ 1 Ori E and ISOY J053526.88–044730.7), enough photometric and spectroscopic data exist to attempt an orbit solution and derive the system parameters. For the remaining systems, we combine our data with literature information to provide a preliminary characterization sufficient to guide follow-up investigations of these rare, benchmark systems.

AK SCO, FIRST DETECTION OF A HIGHLY DISTURBED ATMOSPHERE IN A PRE-MAIN-SEQUENCE CLOSE BINARY

International Nuclear Information System (INIS)

Gomez de Castro, Ana I.

2009-01-01

AK Sco is a unique source: a ∼10 Myr old pre-main-sequence (PMS) spectroscopic binary composed of two nearly equal F5 stars that at periastron are separated by barely 11 stellar radii, so the stellar magnetospheres fill the Roche lobe at periastron. The orbit is not yet circularized (e = 0.47) and very strong tides are expected. This makes AK Sco the ideal laboratory to study the effect of gravitational tides in the stellar magnetic field building up during PMS evolution. In this Letter, the detection of a highly disturbed (σ ≅ 100 km s -1 ) and very dense atmosphere (n e = 1.6 x 10 10 cm -3 ) is reported. Significant line broadening blurs any signs of ion belts or bow shocks in the spectrum of the atmospheric plasma. The radiative losses cannot be accounted for solely by the dissipation of energy from the tidal wave propagating in the stellar atmosphere or by the accreting material. The release of internal energy from the star seems to be the most likely source of the plasma heating. This is the first clear indication of a highly disturbed atmosphere surrounding a PMS close binary.

AK Sco, First Detection of a Highly Disturbed Atmosphere in a Pre-Main-Sequence Close Binary

Science.gov (United States)

Gómez de Castro, Ana I.

2009-06-01

AK Sco is a unique source: a ~10 Myr old pre-main-sequence (PMS) spectroscopic binary composed of two nearly equal F5 stars that at periastron are separated by barely 11 stellar radii, so the stellar magnetospheres fill the Roche lobe at periastron. The orbit is not yet circularized (e = 0.47) and very strong tides are expected. This makes AK Sco the ideal laboratory to study the effect of gravitational tides in the stellar magnetic field building up during PMS evolution. In this Letter, the detection of a highly disturbed (σ sime 100 km s-1) and very dense atmosphere (n e = 1.6 × 1010 cm-3) is reported. Significant line broadening blurs any signs of ion belts or bow shocks in the spectrum of the atmospheric plasma. The radiative losses cannot be accounted for solely by the dissipation of energy from the tidal wave propagating in the stellar atmosphere or by the accreting material. The release of internal energy from the star seems to be the most likely source of the plasma heating. This is the first clear indication of a highly disturbed atmosphere surrounding a PMS close binary.

New radio detections of early-type pre-main-sequence stars

Science.gov (United States)

Skinner, Stephen L.; Brown, Alexander; Linsky, Jeffrey L.

1990-01-01

Results of VLA radio continuum observations of 13 early-type pre-main-sequence stars selected from the 1984 catalog of Finkenzeller and Mundt are presented. The stars HD 259431 and MWC 1080 were detected at 3.6 cm, while HD 200775 and TY CrA were detected at both 3.6 and 6 cm. The flux density of HD 200775 has a frequency dependence consistent with the behavior expected for free-free emission originating in a fully ionized wind. However, an observation in A configuration suggests that the source geometry may not be spherically symmetric. In contrast, the spectral index of TY CrA is negative with a flux behavior implying nonthermal emission. The physical mechanism responsible for the nonthermal emission has not yet been identified, although gyrosynchrotron and synchrotron processes cannot be ruled out.

New radio detections of early-type pre-main-sequence stars

International Nuclear Information System (INIS)

Skinner, S.L.; Brown, A.; Linsky, J.L.

1990-01-01

Results of VLA radio continuum observations of 13 early-type pre-main-sequence stars selected from the 1984 catalog of Finkenzeller and Mundt are presented. The stars HD 259431 and MWC 1080 were detected at 3.6 cm, while HD 200775 and TY CrA were detected at both 3.6 and 6 cm. The flux density of HD 200775 has a frequency dependence consistent with the behavior expected for free-free emission originating in a fully ionized wind. However, an observation in A configuration suggests that the source geometry may not be spherically symmetric. In contrast, the spectral index of TY CrA is negative with a flux behavior implying nonthermal emission. The physical mechanism responsible for the nonthermal emission has not yet been identified, although gyrosynchrotron and synchrotron processes cannot be ruled out. 32 refs

THE QUADRUPLE PRE-MAIN-SEQUENCE SYSTEM LkCa 3: IMPLICATIONS FOR STELLAR EVOLUTION MODELS

International Nuclear Information System (INIS)

Torres, Guillermo; Latham, David W.; Ruíz-Rodríguez, Dary; Prato, L.; Wasserman, Lawrence H.; Badenas, Mariona; Schaefer, G. H.; Mathieu, Robert D.

2013-01-01

We report the discovery that the pre-main-sequence (PMS) object LkCa 3 in the Taurus-Auriga star-forming region is a hierarchical quadruple system of M stars. It was previously known to be a close (∼0.''5) visual pair, with one component being a moderately eccentric 12.94 day single-lined spectroscopic binary. A re-analysis of archival optical spectra complemented by new near-infrared (NIR) spectroscopy shows both visual components to be double lined; the second one has a period of 4.06 days and a circular orbit. In addition to the orbital elements, we determine optical and NIR flux ratios, effective temperatures, and projected rotational velocities for all four stars. Using existing photometric monitoring observations of the system that had previously revealed the rotational period of the primary in the longer-period binary, we also detect the rotational signal of the primary in the 4.06 day binary, which is synchronized with the orbital motion. With only the assumption of coevality, a comparison of all of these constraints with current stellar evolution models from the Dartmouth series points to an age of 1.4 Myr and a distance of 133 pc, consistent with previous estimates for the region and suggesting that the system is on the near side of the Taurus complex. Similar comparisons of the properties of LkCa 3 and the well-known quadruple PMS system GG Tau with the widely used models from the Lyon series for a mixing length parameter of α ML = 1.0 strongly favor the Dartmouth models

Characterizing Intermediate-Mass, Pre-Main-Sequence Stars via X-Ray Emision

Science.gov (United States)

Haze Nunez, Evan; Povich, Matthew Samuel; Binder, Breanna Arlene; Broos, Patrick; Townsley, Leisa K.

2018-01-01

The X-ray emission from intermediate-mass, pre-main-sequence stars (IMPS) can provide useful constraints on the ages of very young (${getting power from the gravitational contraction of the star. Main-sequence late-B and A-type stars are not expected to be strong X-ray emitters, because they lack the both strong winds of more massive stars and the magneto-coronal activity of lower-mass stars. There is, however, mounting evidence that IMPS are powerful intrinsic x-ray emitters during their convection-dominated early evolution, before the development and rapid growth of a radiation zone. We present our prime candidates for intrinsic, coronal X-ray emission from IMPS identified in the Chandra Carina Complex Project. The Carina massive star-forming complex is of special interest due to the wide variation of star formation stages within the region. Candidate IMPS were identified using infrared spectral energy distribution (SED) models. X-ray properties, including thermal plasma temperatures and absorption-corrected fluxes, were derived from XSPEC fits performed using absorption ($N_{H}$) constrained by the extinction values returned by the infrared SED fits. We find that IMPS have systematically higher X-ray luminosities compared to their lower-mass cousins, the TTauri stars.This work is supported by the National Science Foundation under grant CAREER-1454334 and by NASA through Chandra Award 18200040.

Globules, dark clouds, and low mass pre-main sequence stars

International Nuclear Information System (INIS)

Hyland, A.R.

1981-01-01

The current observational and theoretical literature on Bok globules and their relationship to star formation is reviewed. Recent observations of globules at optical, infrared, and far infrared wavelengths are shown to provide important constraints on their structure and evolutionary status, and the suggestion that many globules are gravitationally unstable is seriously questioned. Dark clouds associated with T associations are well-known sites of recent and continuing star formation. In recent years molecular observations and far infrared surveys have provided maps of such regions from which possible sites of star formation may be identified. Optical (Hα) and near infrared surveys have enabled a clear identification of pre-main sequence (PMS) objects within the clouds. Methods of distinguishing these from background objects and the nature of their infrared excesses are examined in the light of recent observations in the near and far infrared. The perennial question as to the existence of anomalous reddening within dark clouds is also investigated. (Auth.)

The Gaia-ESO Survey: the present-day radial metallicity distribution of the Galactic disc probed by pre-main-sequence clusters

Science.gov (United States)

Spina, L.; Randich, S.; Magrini, L.; Jeffries, R. D.; Friel, E. D.; Sacco, G. G.; Pancino, E.; Bonito, R.; Bravi, L.; Franciosini, E.; Klutsch, A.; Montes, D.; Gilmore, G.; Vallenari, A.; Bensby, T.; Bragaglia, A.; Flaccomio, E.; Koposov, S. E.; Korn, A. J.; Lanzafame, A. C.; Smiljanic, R.; Bayo, A.; Carraro, G.; Casey, A. R.; Costado, M. T.; Damiani, F.; Donati, P.; Frasca, A.; Hourihane, A.; Jofré, P.; Lewis, J.; Lind, K.; Monaco, L.; Morbidelli, L.; Prisinzano, L.; Sousa, S. G.; Worley, C. C.; Zaggia, S.

2017-05-01

Context. The radial metallicity distribution in the Galactic thin disc represents a crucial constraint for modelling disc formation and evolution. Open star clusters allow us to derive both the radial metallicity distribution and its evolution over time. Aims: In this paper we perform the first investigation of the present-day radial metallicity distribution based on [Fe/H] determinations in late type members of pre-main-sequence clusters. Because of their youth, these clusters are therefore essential for tracing the current interstellar medium metallicity. Methods: We used the products of the Gaia-ESO Survey analysis of 12 young regions (age ages is not easily explained by the models. Our results reveal a complex interplay of several processes (e.g. star formation activity, initial mass function, supernova yields, gas flows) that controlled the recent evolution of the Milky Way. Based on observations made with the ESO/VLT, at Paranal Observatory, under program 188.B-3002 (The Gaia-ESO Public Spectroscopic Survey).Full Table 1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/601/A70

Pre-main-sequence depletion of Li-6 and Li-7

International Nuclear Information System (INIS)

Proffitt, C.R.; Michaud, G.

1989-01-01

Depletion of Li-6 and Li-7 during premain-sequence contraction has been calculated for several evolutionary sequences. Slightly greater Li-7 depletion was found than by other recent workers. On the premain sequence, Li-6 is depleted by a factor of at least 10 in the present models for stars with T(eff) lower than 6800 K on the main sequence. Because of the shorter destruction time scale for Li-6 as compared to Li-7, the determination of the abundances of these two isotopes would place strict constraints on the structure of premain-sequence stars. 39 refs

A main sequence for quasars

Science.gov (United States)

Marziani, Paola; Dultzin, Deborah; Sulentic, Jack W.; Del Olmo, Ascensión; Negrete, C. A.; Martínez-Aldama, Mary L.; D'Onofrio, Mauro; Bon, Edi; Bon, Natasa; Stirpe, Giovanna M.

2018-03-01

The last 25 years saw a major step forward in the analysis of optical and UV spectroscopic data of large quasar samples. Multivariate statistical approaches have led to the definition of systematic trends in observational properties that are the basis of physical and dynamical modeling of quasar structure. We discuss the empirical correlates of the so-called “main sequence” associated with the quasar Eigenvector 1, its governing physical parameters and several implications on our view of the quasar structure, as well as some luminosity effects associated with the virialized component of the line emitting regions. We also briefly discuss quasars in a segment of the main sequence that includes the strongest FeII emitters. These sources show a small dispersion around a well-defined Eddington ratio value, a property which makes them potential Eddington standard candles.

A Main Sequence for Quasars

Directory of Open Access Journals (Sweden)

Paola Marziani

2018-03-01

Full Text Available The last 25 years saw a major step forward in the analysis of optical and UV spectroscopic data of large quasar samples. Multivariate statistical approaches have led to the definition of systematic trends in observational properties that are the basis of physical and dynamical modeling of quasar structure. We discuss the empirical correlates of the so-called “main sequence” associated with the quasar Eigenvector 1, its governing physical parameters and several implications on our view of the quasar structure, as well as some luminosity effects associated with the virialized component of the line emitting regions. We also briefly discuss quasars in a segment of the main sequence that includes the strongest FeII emitters. These sources show a small dispersion around a well-defined Eddington ratio value, a property which makes them potential Eddington standard candles.

THE MULTIPLE PRE-MAIN-SEQUENCE SYSTEM HBC 515 IN L1622

International Nuclear Information System (INIS)

Reipurth, Bo; Aspin, Colin; Herbig, George

2010-01-01

The bright pre-main-sequence star HBC 515 (HD 288313) located in the L1622 cometary cloud in Orion has been studied extensively with optical/infrared imaging and ultraviolet/optical/infrared spectroscopy. The spectra indicate that HBC 515 is a weakline T Tauri star (TTS) of spectral type K2V. Adaptive optics imaging in the K band reveals that HBC 515 is a binary with two equally bright components separated by 0.''5. A very faint third component is found 5'' to the northwest. Spitzer IRAC and MIPS observations show that at mid-infrared wavelengths this third source dominates the system, suggesting that it is a protostar still embedded in the nascent cloud of HBC 515. The close association of a weakline TTS with a newborn protostar in a multiple system is noteworthy. Two nearby TTSs are likely associated with the HBC 515 multiple system, and the dynamical evolution of the complex that would lead to such a configuration is considered.

Spectroscopic and asteroseismic analysis of the remarkable main-sequence A star KIC 11145123

Science.gov (United States)

Takada-Hidai, Masahide; Kurtz, Donald W.; Shibahashi, Hiromoto; Murphy, Simon J.; Takata, Masao; Saio, Hideyuki; Sekii, Takashi

2017-10-01

A spectroscopic analysis was carried out to clarify the properties of KIC 11145123 - the first main-sequence star with a directly measured core-to-surface rotation profile - based on spectra observed with the High Dispersion Spectrograph (HDS) of the Subaru telescope. The atmospheric parameters (Teff = 7600 K, log g = 4.2, ξ = 3.1 km s-1 and [Fe/H] = -0.71 dex), the radial and rotation velocities, and elemental abundances were obtained by analysing line strengths and fitting line profiles, which were calculated with a 1D LTE model atmosphere. The main properties of KIC 11145123 are: (1) a low [Fe/H] = -0.71 ± 0.11 dex and a high radial velocity of -135.4 ± 0.2 km s-1. These are remarkable among late-A stars. Our best asteroseismic models with this low [Fe/H] have slightly high helium abundance and low masses of 1.4 M⊙. All of these results strongly suggest that KIC 11145123 is a Population II blue straggler; (2) the projected rotation velocity confirms the asteroseismically predicted slow rotation of the star; (3) comparisons of abundance patterns between KIC 11145123 and Am, Ap, and blue stragglers show that KIC 11145123 is neither an Am star nor an Ap star, but has abundances consistent with a blue straggler. We conclude that the remarkably long 100-d rotation period of this star is a consequence of it being a blue straggler, but both pathways for the formation of blue stragglers - merger and mass loss in a binary system - pose difficulties for our understanding of the exceedingly slow rotation. In particular, we show that there is no evidence of any secondary companion star, and we put stringent limits on the possible mass of any such purported companion through the phase modulation technique.

PRE-MAIN-SEQUENCE TURN-ON AS A CHRONOMETER FOR YOUNG CLUSTERS: NGC 346 AS A BENCHMARK

International Nuclear Information System (INIS)

Cignoni, M.; Tosi, M.; Sabbi, E.; Nota, A.; Degl'Innocenti, S.; Moroni, P. G. Prada; Gallagher, J. S.

2010-01-01

We present a novel approach to deriving the age of very young star clusters, by using the Turn-On (TOn). The TOn is the point in the color-magnitude diagram (CMD) where the pre-main sequence (PMS) joins the main sequence (MS). In the MS luminosity function (LF) of the cluster, the TOn is identified as a peak followed by a dip. We propose that by combining the CMD analysis with the monitoring of the spatial distribution of MS stars it is possible to reliably identify the TOn in extragalactic star-forming regions. Compared to alternative methods, this technique is complementary to the turnoff dating and avoids the systematic biases affecting the PMS phase. We describe the method and its uncertainties and apply it to the star-forming region NGC 346, which has been extensively imaged with the Hubble Space Telescope (HST). This study extends the LF approach in crowded extragalactic regions and opens the way for future studies with HST/WFC3, the James Webb Space Telescope and from the ground with adaptive optics.

On precise ZAMSs, the solar color, and pre-main-sequence lithium depletion

International Nuclear Information System (INIS)

Vandenberg, D.A.; Poll, H.E.

1989-01-01

This paper describes a semiempirical main-sequence-fitting method for the determination of distances to stellar systems, which uses a ZAMS locus carefully normalized to the sun, and whose shape is defined by a quartic over the color range for (B-V)0 values between 0.2 and 1.0 such that the morphology of the Pleiades C-M diagram is accurately reproduced. Using this technique, distances were derived for a number of star clusters. It was found that the observed depletion of lithium among cool main-sequence stars in the Hyades and Pleiades can be matched quite well by the present models. Calculations also show that the depletion of Li at a fixed T(eff) along the main sequence is a sensitive function of Fe/H. 98 refs

A search for pre-main-sequence stars in high-latitude molecular clouds. 3: A survey of the Einstein database

Science.gov (United States)

Caillault, Jean-Pierre; Magnani, Loris; Fryer, Chris

1995-01-01

In order to discern whether the high-latitude molecular clouds are regions of ongoing star formation, we have used X-ray emission as a tracer of youthful stars. The entire Einstein database yields 18 images which overlap 10 of the clouds mapped partially or completely in the CO (1-0) transition, providing a total of approximately 6 deg squared of overlap. Five previously unidentified X-ray sources were detected: one has an optical counterpart which is a pre-main-sequence (PMS) star, and two have normal main-sequence stellar counterparts, while the other two are probably extragalactic sources. The PMS star is located in a high Galactic latitude Lynds dark cloud, so this result is not too suprising. The translucent clouds, though, have yet to reveal any evidence of star formation.

A search for pre-main sequence stars in the high-latitude molecular clouds. II - A survey of the Einstein database

Science.gov (United States)

Caillault, Jean-Pierre; Magnani, Loris

1990-01-01

The preliminary results are reported of a survey of every EINSTEIN image which overlaps any high-latitude molecular cloud in a search for X-ray emitting pre-main sequence stars. This survey, together with complementary KPNO and IRAS data, will allow the determination of how prevalent low mass star formation is in these clouds in general and, particularly, in the translucent molecular clouds.

Pre-main-sequence evolution of the sun

International Nuclear Information System (INIS)

Gough, D.

1980-01-01

The phase of solar evolution after the dynamical collapse is considered. The physics of the Kelvin-Helmholtz phase of gravitational collapse is described, attention being given to the early stages of the star when it was completely convective. It is noted that subsequently, a radiative core developed and evolution was controlled by the rate at which heat can diffuse through it by radiative transfer. Since the study of the Kelvin-Helmholtz contraction alone does not give enough information regarding the state of the sun when it first settled down to approximate hydrostatic equilibrium, other stars are studied, and information on the sun is obtained by analogy. Many young solar-type stars, such as the T Tauri stars, are not in the completely convective Hayashi (1961) phase hence it is proposed that the sun was completely mixed soon after its formation, which has some bearing on the sun's chemical structure. It is suggested that the surface of the sun was very nonuniform compared with the photosphere of today. The simple solar evolution model presented gives a good guide to the general way in which the sun contracted to the main sequence

Radio-emission of pre-main sequence stars of the Rho Ophiuchi cloud: observations and interpretation

International Nuclear Information System (INIS)

Andre, P.

1987-11-01

Observations of the radio continuum emission of a young star population have been made at VLA on the whole molecular cloud Rho Ophiuchi, one of the closest site of star formation. A dozen of stellar sources have been detected. Radio emission of some identified objects seems to have a magnetic nature and be produced by gyrosynchrotron mechanism. In particular, one of the sources shows a radio radiation circularly polarized; two other stars have a radiation strongly variable probably due to magnetic eruptions more important than those detected in X radiation. More generally, radio observations select probably a specific population of young stars characterized by magnetic field presence extended on several stellar radii and by absence of dense circumstellar environment. Spatial distribution of these objects suggest, they are younger than most of the pre-main sequence stars [fr

Hubble Tarantula Treasury Project - VI. Identification of Pre-Main-Sequence Stars using Machine Learning techniques

Science.gov (United States)

Ksoll, Victor F.; Gouliermis, Dimitrios A.; Klessen, Ralf S.; Grebel, Eva K.; Sabbi, Elena; Anderson, Jay; Lennon, Daniel J.; Cignoni, Michele; de Marchi, Guido; Smith, Linda J.; Tosi, Monica; van der Marel, Roeland P.

2018-05-01

The Hubble Tarantula Treasury Project (HTTP) has provided an unprecedented photometric coverage of the entire star-burst region of 30 Doradus down to the half Solar mass limit. We use the deep stellar catalogue of HTTP to identify all the pre-main-sequence (PMS) stars of the region, i.e., stars that have not started their lives on the main-sequence yet. The photometric distinction of these stars from the more evolved populations is not a trivial task due to several factors that alter their colour-magnitude diagram positions. The identification of PMS stars requires, thus, sophisticated statistical methods. We employ Machine Learning Classification techniques on the HTTP survey of more than 800,000 sources to identify the PMS stellar content of the observed field. Our methodology consists of 1) carefully selecting the most probable low-mass PMS stellar population of the star-forming cluster NGC2070, 2) using this sample to train classification algorithms to build a predictive model for PMS stars, and 3) applying this model in order to identify the most probable PMS content across the entire Tarantula Nebula. We employ Decision Tree, Random Forest and Support Vector Machine classifiers to categorise the stars as PMS and Non-PMS. The Random Forest and Support Vector Machine provided the most accurate models, predicting about 20,000 sources with a candidateship probability higher than 50 percent, and almost 10,000 PMS candidates with a probability higher than 95 percent. This is the richest and most accurate photometric catalogue of extragalactic PMS candidates across the extent of a whole star-forming complex.

An extensive VLT/X-shooter library of photospheric templates of pre-main sequence stars

Science.gov (United States)

Manara, C. F.; Frasca, A.; Alcalá, J. M.; Natta, A.; Stelzer, B.; Testi, L.

2017-09-01

Context. Studies of the formation and evolution of young stars and their disks rely on knowledge of the stellar parameters of the young stars. The derivation of these parameters is commonly based on comparison with photospheric template spectra. Furthermore, chromospheric emission in young active stars impacts the measurement of mass accretion rates, a key quantity for studying disk evolution. Aims: Here we derive stellar properties of low-mass (M⋆≲ 2 M⊙) pre-main sequence stars without disks, which represent ideal photospheric templates for studies of young stars. We also use these spectra to constrain the impact of chromospheric emission on the measurements of mass accretion rates. The spectra are reduced, flux-calibrated, and corrected for telluric absorption, and are made available to the community. Methods: We derive the spectral type for our targets by analyzing the photospheric molecular features present in their VLT/X-shooter spectra by means of spectral indices and comparison of the relative strength of photospheric absorption features. We also measure effective temperature, gravity, projected rotational velocity, and radial velocity from our spectra by fitting them with synthetic spectra with the ROTFIT tool. The targets have negligible extinction (AVpresented in our previous publication. We perform synthetic photometry on the spectra to derive the typical colors of young stars in different filters. We measure the luminosity of the emission lines present in the spectra and estimate the noise due to chromospheric emission in the measurements of accretion luminosity in accreting stars. Results: We provide a calibration of the photospheric colors of young pre-main sequence stars as a function of their spectral type in a set of standard broad-band optical and near-infrared filters. The logarithm of the noise on the accretion luminosity normalized to the stellar luminosity is roughly constant and equal to -2.3 for targets with masses larger than 1 solar

WHITE-DWARF-MAIN-SEQUENCE BINARIES IDENTIFIED FROM THE LAMOST PILOT SURVEY

International Nuclear Information System (INIS)

Ren Juanjuan; Luo Ali; Li Yinbi; Wei Peng; Zhao Jingkun; Zhao Yongheng; Song Yihan; Zhao Gang

2013-01-01

We present a set of white-dwarf-main-sequence (WDMS) binaries identified spectroscopically from the Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST, also called the Guo Shou Jing Telescope) pilot survey. We develop a color selection criteria based on what is so far the largest and most complete Sloan Digital Sky Survey (SDSS) DR7 WDMS binary catalog and identify 28 WDMS binaries within the LAMOST pilot survey. The primaries in our binary sample are mostly DA white dwarfs except for one DB white dwarf. We derive the stellar atmospheric parameters, masses, and radii for the two components of 10 of our binaries. We also provide cooling ages for the white dwarf primaries as well as the spectral types for the companion stars of these 10 WDMS binaries. These binaries tend to contain hot white dwarfs and early-type companions. Through cross-identification, we note that nine binaries in our sample have been published in the SDSS DR7 WDMS binary catalog. Nineteen spectroscopic WDMS binaries identified by the LAMOST pilot survey are new. Using the 3σ radial velocity variation as a criterion, we find two post-common-envelope binary candidates from our WDMS binary sample

The Lower Main Sequence of Stars in the Solar Neighborhood: Model Predictions Versus Observation

Directory of Open Access Journals (Sweden)

Bartašiūtė S.

2012-09-01

Full Text Available We have used the Simbad database and VizieR catalogue access tools to construct the observational color-absolute magnitude diagrams of nearby K-M dwarfs with precise Hipparcos parallaxes (σπ/π ≤ 0:05. Particular attention has been paid to removing unresolved double/multiple stars and variables. In addition to archival data, we have made use of nearly 2000 new radial-velocity measurements of K-M dwarfs to identify spectroscopic binary candidates. The main sequences, cleaned from unresolved binaries, variable stars, and old population stars which can also widen the sequence due to their presumably lower metallicity, were compared to available solar-metallicity models. Significant offsets of most of the model main-sequence lines are seen with respect to observational data, especially for the lower-mass stars. Only the location and slope of the Victoria-Regina and, partly, BaSTI isochrones match the data quite well.

Combining sequence-based prediction methods and circular dichroism and infrared spectroscopic data to improve protein secondary structure determinations

Directory of Open Access Journals (Sweden)

Lees Jonathan G

2008-01-01

Full Text Available Abstract Background A number of sequence-based methods exist for protein secondary structure prediction. Protein secondary structures can also be determined experimentally from circular dichroism, and infrared spectroscopic data using empirical analysis methods. It has been proposed that comparable accuracy can be obtained from sequence-based predictions as from these biophysical measurements. Here we have examined the secondary structure determination accuracies of sequence prediction methods with the empirically determined values from the spectroscopic data on datasets of proteins for which both crystal structures and spectroscopic data are available. Results In this study we show that the sequence prediction methods have accuracies nearly comparable to those of spectroscopic methods. However, we also demonstrate that combining the spectroscopic and sequences techniques produces significant overall improvements in secondary structure determinations. In addition, combining the extra information content available from synchrotron radiation circular dichroism data with sequence methods also shows improvements. Conclusion Combining sequence prediction with experimentally determined spectroscopic methods for protein secondary structure content significantly enhances the accuracy of the overall results obtained.

MASS LOSS IN PRE-MAIN-SEQUENCE STARS VIA CORONAL MASS EJECTIONS AND IMPLICATIONS FOR ANGULAR MOMENTUM LOSS

Energy Technology Data Exchange (ETDEWEB)

Aarnio, Alicia N. [Astronomy Department, University of Michigan, 830 Dennison Building, 500 Church Street, Ann Arbor, MI 48109 (United States); Matt, Sean P. [Laboratoire AIM Paris-Saclay, CEA/Irfu Universite Paris-Diderot CNRS/INSU, F-91191 Gif-sur-Yvette (France); Stassun, Keivan G., E-mail: aarnio@umich.edu [Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States)

2012-11-20

We develop an empirical model to estimate mass-loss rates via coronal mass ejections (CMEs) for solar-type pre-main-sequence (PMS) stars. Our method estimates the CME mass-loss rate from the observed energies of PMS X-ray flares, using our empirically determined relationship between solar X-ray flare energy and CME mass: log (M {sub CME}[g]) = 0.63 Multiplication-Sign log (E {sub flare}[erg]) - 2.57. Using masses determined for the largest flaring magnetic structures observed on PMS stars, we suggest that this solar-calibrated relationship may hold over 10 orders of magnitude in flare energy and 7 orders of magnitude in CME mass. The total CME mass-loss rate we calculate for typical solar-type PMS stars is in the range 10{sup -12}-10{sup -9} M {sub Sun} yr{sup -1}. We then use these CME mass-loss rate estimates to infer the attendant angular momentum loss leading up to the main sequence. Assuming that the CME outflow rate for a typical {approx}1 M {sub Sun} T Tauri star is <10{sup -10} M {sub Sun} yr{sup -1}, the resulting spin-down torque is too small during the first {approx}1 Myr to counteract the stellar spin-up due to contraction and accretion. However, if the CME mass-loss rate is {approx}> 10{sup -10} M {sub Sun} yr{sup -1}, as permitted by our calculations, then the CME spin-down torque may influence the stellar spin evolution after an age of a few Myr.

X-ray sources in regions of star formation. II. The pre-main-sequence G star HDE 283572

International Nuclear Information System (INIS)

Walter, F.M.; Brown, A.; Linsky, J.L.; Rydgren, A.E.; Vrba, F.; Joint Institute for Laboratory Astrophysics, Boulder, CO; Computer Sciences Corp., El Segundo, CA; Naval Observatory, Flagstaff, AZ)

1987-01-01

This paper reports the detection of HDE 283572, a ninth-magnitude G star 8 arcmin south of RY Tau, as a bright X-ray source. The observations reveal this object to be a fairly massive (about 2 solar masses) pre-main-sequence star associated with the Taurus-Auriga star formation complex. It exhibits few of the characteristics of the classical T Tauri stars and is a good example of a naked T Tauri star. The star is a mid-G subgiant, of about three solar radii and rotates with a period of 1.5 d. The coronal and chromospheric surface fluxes are similar to those of the most active late type stars (excluding T Tauri stars). The X-ray and UV lines most likely arise in different atmospheric structures. Radiative losses are some 1000 times the quiet solar value and compare favorably with those of T Tauri stars. 49 references

Main sequence mass loss

International Nuclear Information System (INIS)

Brunish, W.M.; Guzik, J.A.; Willson, L.A.; Bowen, G.

1987-01-01

It has been hypothesized that variable stars may experience mass loss, driven, at least in part, by oscillations. The class of stars we are discussing here are the δ Scuti variables. These are variable stars with masses between about 1.2 and 2.25 M/sub θ/, lying on or very near the main sequence. According to this theory, high rotation rates enhance the rate of mass loss, so main sequence stars born in this mass range would have a range of mass loss rates, depending on their initial rotation velocity and the amplitude of the oscillations. The stars would evolve rapidly down the main sequence until (at about 1.25 M/sub θ/) a surface convection zone began to form. The presence of this convective region would slow the rotation, perhaps allowing magnetic braking to occur, and thus sharply reduce the mass loss rate. 7 refs

The Pisa pre-main sequence tracks and isochrones. A database covering a wide range of Z, Y, mass, and age values

Science.gov (United States)

Tognelli, E.; Prada Moroni, P. G.; Degl'Innocenti, S.

2011-09-01

Context. In recent years new observations of pre-main sequence stars (pre-MS) with Z ≤ Z⊙ have been made available. To take full advantage of the continuously growing amount of data of pre-MS stars in different environments, we need to develop updated pre-MS models for a wide range of metallicity to assign reliable ages and masses to the observed stars. Aims: We present updated evolutionary pre-MS models and isochrones for a fine grid of mass, age, metallicity, and helium values. Methods: We use a standard and well-tested stellar evolutionary code (i.e. FRANEC), that adopts outer boundary conditions from detailed and realistic atmosphere models. In this code, we incorporate additional improvements to the physical inputs related to the equation of state and the low temperature radiative opacities essential to computing low-mass stellar models. Results: We make available via internet a large database of pre-MS tracks and isochrones for a wide range of chemical compositions (Z = 0.0002-0.03), masses (M = 0.2-7.0 M⊙), and ages (1-100 Myr) for a solar-calibrated mixing length parameter α (i.e. 1.68). For each chemical composition, additional models were computed with two different mixing length values, namely α = 1.2 and 1.9. Moreover, for Z ≥ 0.008, we also provided models with two different initial deuterium abundances. The characteristics of the models have been discussed in detail and compared with other work in the literature. The main uncertainties affecting theoretical predictions have been critically discussed. Comparisons with selected data indicate that there is close agreement between theory and observation. Tracks and isochrones are available on the web at the http://astro.df.unipi.it/stellar-models/Tracks and isochrones are also available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/533/A109

A tale of two anomalies: Depletion, dispersion, and the connection between the stellar lithium spread and inflated radii on the pre-main sequence

Energy Technology Data Exchange (ETDEWEB)

Somers, Garrett; Pinsonneault, Marc H., E-mail: somers@astronomy.ohio-state.edu, E-mail: pinsono@astronomy.ohio-state.edu [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43201 (United States)

2014-07-20

We investigate lithium depletion in standard stellar models (SSMs) and main sequence (MS) open clusters, and explore the origin of the Li dispersion in young, cool stars of equal mass, age, and composition. We first demonstrate that SSMs accurately predict the Li abundances of solar analogs at the zero-age main sequence (ZAMS) within theoretical uncertainties. We then measure the rate of MS Li depletion by removing the [Fe/H]-dependent ZAMS Li pattern from three well-studied clusters, and comparing the detrended data. MS depletion is found to be mass-dependent, in the sense of more depletion at low mass. A dispersion in Li abundance at fixed T{sub eff} is nearly universal, and sets in by ∼200 Myr. We discuss mass and age dispersion trends, and the pattern is mixed. We argue that metallicity impacts the ZAMS Li pattern, in agreement with theoretical expectations but contrary to the findings of some previous studies, and suggest Li as a test of cluster metallicity. Finally, we argue that a radius dispersion in stars of fixed mass and age, during the epoch of pre-MS Li destruction, is responsible for the spread in Li abundances and the correlation between rotation and Li in young cool stars, most well known in the Pleiades. We calculate stellar models, inflated to match observed radius anomalies in magnetically active systems, and the resulting range of Li abundances reproduces the observed patterns of young clusters. We discuss ramifications for pre-MS evolutionary tracks and age measurements of young clusters, and suggest an observational test.

A tale of two anomalies: Depletion, dispersion, and the connection between the stellar lithium spread and inflated radii on the pre-main sequence

International Nuclear Information System (INIS)

Somers, Garrett; Pinsonneault, Marc H.

2014-01-01

We investigate lithium depletion in standard stellar models (SSMs) and main sequence (MS) open clusters, and explore the origin of the Li dispersion in young, cool stars of equal mass, age, and composition. We first demonstrate that SSMs accurately predict the Li abundances of solar analogs at the zero-age main sequence (ZAMS) within theoretical uncertainties. We then measure the rate of MS Li depletion by removing the [Fe/H]-dependent ZAMS Li pattern from three well-studied clusters, and comparing the detrended data. MS depletion is found to be mass-dependent, in the sense of more depletion at low mass. A dispersion in Li abundance at fixed T eff is nearly universal, and sets in by ∼200 Myr. We discuss mass and age dispersion trends, and the pattern is mixed. We argue that metallicity impacts the ZAMS Li pattern, in agreement with theoretical expectations but contrary to the findings of some previous studies, and suggest Li as a test of cluster metallicity. Finally, we argue that a radius dispersion in stars of fixed mass and age, during the epoch of pre-MS Li destruction, is responsible for the spread in Li abundances and the correlation between rotation and Li in young cool stars, most well known in the Pleiades. We calculate stellar models, inflated to match observed radius anomalies in magnetically active systems, and the resulting range of Li abundances reproduces the observed patterns of young clusters. We discuss ramifications for pre-MS evolutionary tracks and age measurements of young clusters, and suggest an observational test.

Time Variability of the Dust Sublimation Zones in Pre-Main Sequence Disk Systems

Science.gov (United States)

Sitko, Michael L.; Carpenter, W. J.; Grady, C. A.; Russel, R. W.; Lynch, D. K.; Rudy, R. J.; Mazuk, S. M.; Venturini, C. C.; Kimes, R. L.; Beerman, L. C.;

EXTENDED MAGNETOSPHERES IN PRE-MAIN-SEQUENCE EVOLUTION: FROM T TAURI STARS TO THE BROWN DWARF LIMIT

Energy Technology Data Exchange (ETDEWEB)

Gomez de Castro, Ana I.; Marcos-Arenal, Pablo [Grupo de Investigacion Complutense AEGORA, Universidad Complutense de Madrid, 28040 Madrid (Spain)

2012-04-20

Low-mass pre-main-sequence stars, i.e., T Tauri stars (TTSs), strongly radiate at high energies, from X-rays to the ultraviolet (UV). This excess radiation with respect to main-sequence cool stars (MSCSs) is associated with the accretion process, i.e., it is produced in the extended magnetospheres, in the accretion shocks on the stellar surface, and in the outflows. Although evidence of accretion shocks and outflow contribution to the high-energy excess have been recently addressed, there is not an updated revision of the magnetospheric contribution. This article addresses this issue. The UV observations of the TTSs in the well-known Taurus region have been analyzed together with the XMM-Newton observations compiled in the XEST survey. For the first time the high sensitivity of the Hubble Space Telescope UV instrumentation has allowed measurement of the UV line fluxes of TTSs to M8 type. UV- and X-ray-normalized fluxes have been determined to study the extent and properties of the TTS magnetospheres as a class. They have been compared with the atmospheres of the MSCSs. The main results from this analysis are (1) the normalized fluxes of all the tracers are correlated; this correlation is independent of the broad mass range and the hardness of the X-ray radiation field; (2) the TTS correlations are different than the MSCS correlations; (3) there is a very significant excess emission in O I in the TTSs compared with MSCSs that seems to be caused by recombination radiation from the disk atmosphere after photoionization by extreme UV radiation; the Fe II/Mg II recombination continuum has also been detected in several TTSs and most prominently in AA Tau; and (4) the normalized flux of the UV tracers anticorrelates with the strength of the X-ray flux, i.e., the stronger the X-ray surface flux is, the weaker the observed UV flux. This last behavior is counterintuitive within the framework of stellar dynamo theory and suggests that UV emission can be produced in the

Nitrogen chronology of massive main sequence stars

NARCIS (Netherlands)

Köhler, K.; Borzyszkowski, M.; Brott, I.; Langer, N.; de Koter, A.

2012-01-01

Context. Rotational mixing in massive main sequence stars is predicted to monotonically increase their surface nitrogen abundance with time. Aims. We use this effect to design a method for constraining the age and the inclination angle of massive main sequence stars, given their observed luminosity,

Main-sequence photometry in NGC 2808

International Nuclear Information System (INIS)

Buonanno, R.; Corsi, C.E.; Fusi Pecci, F.; Harris, W.E.

1984-01-01

We have obtained a color-magnitude diagram for the southern globular cluster NGC 2808, to V/sub lim/approx. =21 (about 2 mag below the main-sequence turnoff). The internal photographic errors are sigma/sub V/approx. =0.02, sigma/sub B/-Vapprox. =0.03, small enough to permit a precise definition of the turnoff region and an estimate of the ''cosmic scatter'' along the main sequence. Fitting of the CMD to VandenBerg's [Astrophys. J. Suppl. 51, 29 (1983)] isochrones shows that an excellent match to the observations is achieved for model parameters of Yapprox. =0.2, Zapprox. =0.003 ([Fe/H]approx. =-0.8), and an age of (16 +- 2) billion years. All these characteristics are within the expected range from other observational constraints; no new clues from the main-sequence data alone have arisen to help explain the presence of the anomalous blue horizontal-branch stars

Empirical tests of pre-main-sequence stellar evolution models with eclipsing binaries

Science.gov (United States)

Stassun, Keivan G.; Feiden, Gregory A.; Torres, Guillermo

2014-06-01

We examine the performance of standard pre-main-sequence (PMS) stellar evolution models against the accurately measured properties of a benchmark sample of 26 PMS stars in 13 eclipsing binary (EB) systems having masses 0.04-4.0 M⊙ and nominal ages ≈1-20 Myr. We provide a definitive compilation of all fundamental properties for the EBs, with a careful and consistent reassessment of observational uncertainties. We also provide a definitive compilation of the various PMS model sets, including physical ingredients and limits of applicability. No set of model isochrones is able to successfully reproduce all of the measured properties of all of the EBs. In the H-R diagram, the masses inferred for the individual stars by the models are accurate to better than 10% at ≳1 M⊙, but below 1 M⊙ they are discrepant by 50-100%. Adjusting the observed radii and temperatures using empirical relations for the effects of magnetic activity helps to resolve the discrepancies in a few cases, but fails as a general solution. We find evidence that the failure of the models to match the data is linked to the triples in the EB sample; at least half of the EBs possess tertiary companions. Excluding the triples, the models reproduce the stellar masses to better than ∼10% in the H-R diagram, down to 0.5 M⊙, below which the current sample is fully contaminated by tertiaries. We consider several mechanisms by which a tertiary might cause changes in the EB properties and thus corrupt the agreement with stellar model predictions. We show that the energies of the tertiary orbits are comparable to that needed to potentially explain the scatter in the EB properties through injection of heat, perhaps involving tidal interaction. It seems from the evidence at hand that this mechanism, however it operates in detail, has more influence on the surface properties of the stars than on their internal structure, as the lithium abundances are broadly in good agreement with model predictions. The

Prostate cancer in magnetic resonance imaging: diagnostic utilites of spectroscopic sequences

International Nuclear Information System (INIS)

Caivano, Rocchina; Cirillo, Patrizia; Lotumolo, Antonella; Fortunato, Giovanna; Zandolino, Alexis; Cammarota, Aldo; Balestra, Antonio; Macarini, Luca; Vita, Giulia

2012-01-01

The aim of our work is to determine the efficacy of a combined study 3 Tesla Magnetic Resonance Imaging (3T MRI), with phased-array coil, for the detection of prostate cancer using magnetic resonance spectroscopy (MRS) and diffusion-weighted images (DWI) in identifying doubt nodules. In this study, we prospectively studied 46 patients who consecutively underwent digital-rectal exploration for high doses of prostate specific antigen (PSA), as well as a MRI examination and a subsequent rectal biopsy. The study of magnetic resonance imaging was performed with a Philips Achieva 3T scanner and phased-array coil. The images were obtained with turbo spin-echo sequences T2-weighted images, T1-weighted before and after the administration of contrast medium, DWI sequences and 3D spectroscopic sequences. The ultrasound-guided prostate biopsy was performed approximately 15 days after the MRI. The data obtained from MR images and spectroscopy were correlated with histological data. MRI revealed sensitivity and specificity of 88% and 61% respectively and positive predictive value (PPV) of 73%, negative predicted value (NPV) of 81% and accuracy of 76%. In identifying the location of prostate cancer, the sensitivity of 3T MRS was 92%, with a specificity of 89%, PPV of 87%, NPV of 88% and accuracy of 87%; DWI showed a sensitivity of 88%, specificity of 61%, PPV of 73%, NPV of 81% and accuracy of 76%. The 3T MR study with phased-array coil and the use of DWI and spectroscopic sequences, in addition to T2-weighted sequences, revealed to be accurate in the diagnosis of prostate cancer and in the identification of nodules to be biopsied. It may be indicated as a resolute way before biopsy in patients with elevated PSA value and can be proposed in the staging and follow-up.

SPECTROSCOPIC CONFIRMATION OF A MASSIVE RED-SEQUENCE-SELECTED GALAXY CLUSTER AT z = 1.34 IN THE SpARCS-SOUTH CLUSTER SURVEY

International Nuclear Information System (INIS)

Wilson, Gillian; Demarco, Ricardo; Muzzin, Adam; Yee, H. K. C.; Lacy, Mark; Surace, Jason; Gilbank, David; Blindert, Kris; Hoekstra, Henk; Majumdar, Subhabrata; Gardner, Jonathan P.; Gladders, Michael D.; Lonsdale, Carol

2009-01-01

The Spitzer Adaptation of the Red-sequence Cluster Survey (SpARCS) is a z'-passband imaging survey, consisting of deep (z' ≅ 24 AB) observations made from both hemispheres using the CFHT 3.6 m and CTIO 4 m telescopes. The survey was designed with the primary aim of detecting galaxy clusters at z > 1. In tandem with pre-existing 3.6 μm observations from the Spitzer Space Telescope SWIRE Legacy Survey, SpARCS detects clusters using an infrared adaptation of the two-filter red-sequence cluster technique. The total effective area of the SpARCS cluster survey is 41.9 deg 2 . In this paper, we provide an overview of the 13.6 deg 2 Southern CTIO/MOSAIC II observations. The 28.3 deg 2 Northern CFHT/MegaCam observations are summarized in a companion paper by Muzzin et al. In this paper, we also report spectroscopic confirmation of SpARCS J003550-431224, a very rich galaxy cluster at z = 1.335, discovered in the ELAIS-S1 field. To date, this is the highest spectroscopically confirmed redshift for a galaxy cluster discovered using the red-sequence technique. Based on nine confirmed members, SpARCS J003550-431224 has a preliminary velocity dispersion of 1050 ± 230 km s -1 . With its proven capability for efficient cluster detection, SpARCS is a demonstration that we have entered an era of large, homogeneously selected z > 1 cluster surveys.

Automated cleaning and pre-processing of immunoglobulin gene sequences from high-throughput sequencing

Directory of Open Access Journals (Sweden)

Miri eMichaeli

2012-12-01

Full Text Available High throughput sequencing (HTS yields tens of thousands to millions of sequences that require a large amount of pre-processing work to clean various artifacts. Such cleaning cannot be performed manually. Existing programs are not suitable for immunoglobulin (Ig genes, which are variable and often highly mutated. This paper describes Ig-HTS-Cleaner (Ig High Throughput Sequencing Cleaner, a program containing a simple cleaning procedure that successfully deals with pre-processing of Ig sequences derived from HTS, and Ig-Indel-Identifier (Ig Insertion – Deletion Identifier, a program for identifying legitimate and artifact insertions and/or deletions (indels. Our programs were designed for analyzing Ig gene sequences obtained by 454 sequencing, but they are applicable to all types of sequences and sequencing platforms. Ig-HTS-Cleaner and Ig-Indel-Identifier have been implemented in Java and saved as executable JAR files, supported on Linux and MS Windows. No special requirements are needed in order to run the programs, except for correctly constructing the input files as explained in the text. The programs' performance has been tested and validated on real and simulated data sets.

Elevation or Suppression? The Resolved Star Formation Main Sequence of Galaxies with Two Different Assembly Modes

Science.gov (United States)

Liu, Qing; Wang, Enci; Lin, Zesen; Gao, Yulong; Liu, Haiyang; Berhane Teklu, Berzaf; Kong, Xu

2018-04-01

We investigate the spatially resolved star formation main sequence in star-forming galaxies using Integral Field Spectroscopic observations from the Mapping Nearby Galaxies at the Apache Point Observatory survey. We demonstrate that the correlation between the stellar mass surface density (Σ*) and star formation rate surface density (ΣSFR) holds down to the sub-galactic scale, leading to the sub-galactic main sequence (SGMS). By dividing galaxies into two populations based on their recent mass assembly modes, we find the resolved main sequence in galaxies with the “outside-in” mode is steeper than that in galaxies with the “inside-out” mode. This is also confirmed on a galaxy-by-galaxy level, where we find the distributions of SGMS slopes for individual galaxies are clearly separated for the two populations. When normalizing and stacking the SGMS of individual galaxies on one panel for the two populations, we find that the inner regions of galaxies with the “inside-out” mode statistically exhibit a suppression in star formation, with a less significant trend in the outer regions of galaxies with the “outside-in” mode. In contrast, the inner regions of galaxies with “outside-in” mode and the outer regions of galaxies with “inside-out” mode follow a slightly sublinear scaling relation with a slope ∼0.9, which is in good agreement with previous findings, suggesting that they are experiencing a universal regulation without influences of additional physical processes.

Spectroscopic and shadowgraphic analysis of laser induced plasmas in the orthogonal double pulse pre-ablation configuration

International Nuclear Information System (INIS)

Cristoforetti, G.; Legnaioli, S.; Pardini, L.; Palleschi, V.; Salvetti, A.; Tognoni, E.

2006-01-01

This work focuses on the study of the plumes obtained in the double pulse orthogonal Laser Induced Breakdown Spectroscopy (LIBS) in the pre-ablation configuration using both spectroscopic and shadowgraphic approaches. Single and double pulse LIBS experiments were carried out on a brass sample in air. Both the distance of the air plasma from the target surface and the interpulse delay were varied (respectively in the range 0.1-4.2 mm and up to 50 μs) revealing a significant variation of the plasma emission and of the plume-shock wave dynamical expansion in different cases. The intensity of both atomic and ionized zinc lines was measured in all the cases, allowing the calculation of the spatially averaged temperature and electron density and an estimation of the ablated mass. The line intensities and the thermodynamic parameters obtained by the spectroscopic measurements were discussed bearing in mind the dynamical expansion characteristics obtained from the shadowgraphic approach. All the data seem to be consistent with the model previously proposed for the double pulse collinear configuration where the line enhancement is mainly attributed to the ambient gas rarefaction produced by the first laser pulse, which causes a less effective shielding of the second laser pulse

Main sequences defined by Hyades and field stars

International Nuclear Information System (INIS)

Upgren, A.R.

1978-01-01

The author reviews the main sequences defined by members of the Hyades cluster and by the field stars in the solar neighborhood. For this purpose, the discussion is limited primarily to the stars of the lower portions of the main sequence, especially those of spectral classes K and early M. There are two reasons for emphasis on the faint red dwarf stars. First, the value of a parallax depends on its size or, more accurately, on the error in parallax divided by the parallax itself. Large parallaxes of high precision occur in large numbers only for stars inhabiting the lower main sequence. Furthermore, brighter stars of earlier spectral classes are more likely to be influenced by evolutionary effects which may differ between the Hyades and field stars, and which are difficult to calibrate. (Auth.)

ON THE MULTIPLICITY OF THE ZERO-AGE MAIN-SEQUENCE O STAR HERSCHEL 36

International Nuclear Information System (INIS)

Arias, Julia I.; Barba, Rodolfo H.; Gamen, Roberto C.; Morrell, Nidia I.; Apellaniz, Jesus MaIz; Alfaro, Emilio J.; Sota, Alfredo; Walborn, Nolan R.; Bidin, Christian Moni

2010-01-01

We present the analysis of high-resolution optical spectroscopic observations of the zero-age main-sequence O star Herschel 36 spanning six years. This star is definitely a multiple system, with at least three components detected in its spectrum. Based on our radial-velocity (RV) study, we propose a picture of a close massive binary and a more distant companion, most probably in wide orbit about each other. The orbital solution for the binary, whose components we identify as O9 V and B0.5 V, is characterized by a period of 1.5415 ± 0.0006 days. With a spectral type O7.5 V, the third body is the most luminous component of the system and also presents RV variations with a period close to 498 days. Some possible hypotheses to explain the variability are briefly addressed and further observations are suggested.

Hydrodynamic ejection of bipolar flows from objects undergoing disk accretion: T Tauri stars, massive pre-main-sequence objects, and cataclysmic variables

International Nuclear Information System (INIS)

Torbett, M.V.

1984-01-01

A general mechanism is presented for generating pressure-driven winds that are intrinsically bipolar from objects undergoing disk accretion. The energy librated in a boundary layer shock as the disk matter impacts the central object is shown to be sufficient to eject a fraction βapprox.10 -2 to 10 -3 of the accreted mass. These winds are driven by a mechanism that accelerates the flow perpendicular to the plane of the disk and can therefore account for the bipolar geometry of the mass loss observed near young stars. The mass loss contained in these winds is comparable to that inferred for young stars. Thus, disk accretion-driven winds may constitute the T Tauri phase of stellar evolution. This mechanism is generally applicable, and thus massive pre-main-sequence objects as well as cataclysmic variables at times of enhanced accretion are predicted to eject bipolar outflows as well. Unmagnetized accreting neutron stas are also expected to eject bipolar flows. Since this mechanism requires stellar surfaces, however, it will not operate in disk accretion onto black holes

The double main sequence of Omega Centauri

Science.gov (United States)

Bedin, L. R.; Piotto, G.; Anderson, J.; King, I. R.; Cassisi, S.; Momany, Y.

Recent, high precision photometry of Omega Centauri, the biggest Galactic globular cluster, has been obtained with Hubble Space Telescope (HST). The color magnitude diagram reveals an unexpected bifurcation of colors in the main sequence (MS). The newly found double MS, the multiple turnoffs and subgiant branches, and other sequences discovered in the past along the red giant branch of this cluster add up to a fascinating but frustrating puzzle. Among the possible explanations for the blue main sequence an anomalous overabundance of helium is suggested. The hypothesis will be tested with a set of FLAMES@VLT data we have recently obtained (ESO DDT program), and with forthcoming ACS@HST images. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555.

Did A Planet Survive A Post-Main Sequence Evolutionary Event?

Science.gov (United States)

Sorber, Rebecca; Jang-Condell, Hannah; Zimmerman, Mara

2018-06-01

The GL86 is star system approximately 10 pc away with a main sequence K- type ~ 0.77 M⊙ star (GL 86A) with a white dwarf ~0.49 M⊙ companion (GL86 B). The system has a ~ 18.4 AU semi-major axis, an orbital period of ~353 yrs, and an eccentricity of ~ 0.39. A 4.5 MJ planet orbits the main sequence star with a semi-major axis of 0.113 AU, an orbital period of 15.76 days, in a near circular orbit with an eccentricity of 0.046. If we assume that this planet was formed during the time when the white dwarf was a main sequence star, it would be difficult for the planet to have remained in a stable orbit during the post-main sequence evolution of GL86 B. The post-main sequence evolution with planet survival will be examined by modeling using the program Mercury (Chambers 1999). Using the model, we examine the origins of the planet: whether it formed before or after the post-main sequence evolution of GL86B. The modeling will give us insight into the dynamical evolution of, not only, the binary star system, but also the planet’s life cycle.

AN M DWARF COMPANION TO AN F-TYPE STAR IN A YOUNG MAIN-SEQUENCE BINARY

Energy Technology Data Exchange (ETDEWEB)

Eigmüller, Ph.; Csizmadia, Sz.; Erikson, A.; Fridlund, M.; Pasternacki, Th.; Rauer, H. [Institute of Planetary Research, German Aerospace Center Rutherfordstr. 2, D-12489 Berlin (Germany); Eislöffel, J.; Lehmann, H.; Hartmann, M.; Hatzes, A. [Thüringer Landessternwarte Tautenburg Sternwarte 5, D-07778 Tautenburg (Germany); Tkachenko, A. [Instituut voor Sterrenkunde, KU Leuven Celestijnenlaan 200D, 3001 Leuven (Belgium); Voss, H., E-mail: philipp.eigmueller@dlr.de [Universitat de Barcelona, Department of Astronomy and Meteorology Martí i Franquès, 1, E-08028 Barcelona (Spain)

2016-03-15

Only a few well characterized very low-mass M dwarfs are known today. Our understanding of M dwarfs is vital as these are the most common stars in our solar neighborhood. We aim to characterize the properties of a rare F+dM stellar system for a better understanding of the low-mass end of the Hertzsprung–Russel diagram. We used photometric light curves and radial velocity follow-up measurements to study the binary. Spectroscopic analysis was used in combination with isochrone fitting to characterize the primary star. The primary star is an early F-type main-sequence star with a mass of (1.493 ± 0.073) M{sub ⊙} and a radius of (1.474 ± 0.040) R{sub ⊙}. The companion is an M dwarf with a mass of (0.188 ± 0.014) M{sub ⊙} and a radius of (0.234 ± 0.009) R{sub ⊙}. The orbital period is (1.35121 ± 0.00001) days. The secondary star is among the lowest-mass M dwarfs known to date. The binary has not reached a 1:1 spin–orbit synchronization. This indicates a young main-sequence binary with an age below ∼250 Myr. The mass–radius relation of both components are in agreement with this finding.

Circumstellar Material on and off the Main Sequence

Science.gov (United States)

Steele, Amy; Debes, John H.; Deming, Drake

2017-06-01

There is evidence of circumstellar material around main sequence, giant, and white dwarf stars that originates from the small-body population of planetary systems. These bodies tell us something about the chemistry and evolution of protoplanetary disks and the planetary systems they form. What happens to this material as its host star evolves off the main sequence, and how does that inform our understanding of the typical chemistry of rocky bodies in planetary systems? In this talk, I will discuss the composition(s) of circumstellar material on and off the main sequence to begin to answer the question, “Is Earth normal?” In particular, I look at three types of debris disks to understand the typical chemistry of planetary systems—young debris disks, debris disks around giant stars, and dust around white dwarfs. I will review the current understanding on how to infer dust composition for each class of disk, and present new work on constraining dust composition from infrared excesses around main sequence and giant stars. Finally, dusty and polluted white dwarfs hold a unique key to our understanding of the composition of rocky bodies around other stars. In particular, I will discuss WD1145+017, which has a transiting, disintegrating planetesimal. I will review what we know about this system through high speed photometry and spectroscopy and present new work on understanding the complex interplay of physics that creates white dwarf pollution from the disintegration of rocky bodies.

Lithium depletion and rotation in main-sequence stars

International Nuclear Information System (INIS)

Balachandran, S.

1990-01-01

Lithium abundances were measured in nearly 200 old disk-population F stars to examine the effects of rotational braking on the depletion of Li. The sample was selected to be slightly evolved off the main sequence so that the stars have completed all the Li depletion they will undergo on the main sequence. A large scatter in Li abundances in the late F stars is found, indicating that the Li depletion is not related to age and spectral type alone. Conventional depletion mechanisms like convective overshoot and microscopic diffusion are unable to explain Li depletion in F stars with thin convective envelopes and are doubly taxed to explain such a scatter. No correlation is found between Li abundance and the present projected rotational velocity and some of the most rapid rotators are undepleted, ruling out meridional circulation as the cause of Li depletion. There is a somewhat larger spread in Li abundances in the spun-down late F stars compared to the early F stars which should remain rotationally unaltered on the main sequence. 85 refs

ON THE RELIABILITY OF STELLAR AGES AND AGE SPREADS INFERRED FROM PRE-MAIN-SEQUENCE EVOLUTIONARY MODELS

International Nuclear Information System (INIS)

Hosokawa, Takashi; Offner, Stella S. R.; Krumholz, Mark R.

2011-01-01

We revisit the problem of low-mass pre-main-sequence stellar evolution and its observational consequences for where stars fall on the Hertzsprung-Russell diagram (HRD). In contrast to most previous work, our models follow stars as they grow from small masses via accretion, and we perform a systematic study of how the stars' HRD evolution is influenced by their initial radius, by the radiative properties of the accretion flow, and by the accretion history, using both simple idealized accretion histories and histories taken from numerical simulations of star cluster formation. We compare our numerical results to both non-accreting isochrones and to the positions of observed stars in the HRD, with a goal of determining whether both the absolute ages and the age dispersions inferred from non-accreting isochrones are reliable. We show that non-accreting isochrones can sometimes overestimate stellar ages for more massive stars (those with effective temperatures above ∼3500 K), thereby explaining why non-accreting isochrones often suggest a systematic age difference between more and less massive stars in the same cluster. However, we also find the only way to produce a similar overestimate for the ages of cooler stars is if these stars grow from ∼0.01 M sun seed protostars that are an order of magnitude smaller than predicted by current theoretical models, and if the size of the seed protostar correlates systematically with the final stellar mass at the end of accretion. We therefore conclude that, unless both of these conditions are met, inferred ages and age spreads for cool stars are reliable, at least to the extent that the observed bolometric luminosities and temperatures are accurate. Finally, we note that the time dependence of the mass accretion rate has remarkably little effect on low-mass stars' evolution on the HRD, and that such time dependence may be neglected for all stars except those with effective temperatures above ∼4000 K.

Stochastically excited oscillations on the upper main sequence

DEFF Research Database (Denmark)

Antoci, Victoria

2013-01-01

Convective envelopes in stars on the main sequence are usually connected only with stars of spectral types F5 or later. However, observations as well as theory indicate that the convective outer layers in earlier stars, despite being shallow, are still effective and turbulent enough to stochastic......Convective envelopes in stars on the main sequence are usually connected only with stars of spectral types F5 or later. However, observations as well as theory indicate that the convective outer layers in earlier stars, despite being shallow, are still effective and turbulent enough...... Pulsating B and Be stars, all in the context of solar-like oscillations....

STELLAR DIAMETERS AND TEMPERATURES. III. MAIN-SEQUENCE A, F, G, AND K STARS: ADDITIONAL HIGH-PRECISION MEASUREMENTS AND EMPIRICAL RELATIONS

International Nuclear Information System (INIS)

Boyajian, Tabetha S.; Jones, Jeremy; White, Russel; McAlister, Harold A.; Gies, Douglas; Von Braun, Kaspar; Van Belle, Gerard; Farrington, Chris; Schaefer, Gail; Ten Brummelaar, Theo A.; Sturmann, Laszlo; Sturmann, Judit; Turner, Nils H.; Goldfinger, P. J.; Vargas, Norm; Ridgway, Stephen

2013-01-01

Based on CHARA Array measurements, we present the angular diameters of 23 nearby, main-sequence stars, ranging from spectral types A7 to K0, 5 of which are exoplanet host stars. We derive linear radii, effective temperatures, and absolute luminosities of the stars using Hipparcos parallaxes and measured bolometric fluxes. The new data are combined with previously published values to create an Angular Diameter Anthology of measured angular diameters to main-sequence stars (luminosity classes V and IV). This compilation consists of 125 stars with diameter uncertainties of less than 5%, ranging in spectral types from A to M. The large quantity of empirical data is used to derive color-temperature relations to an assortment of color indices in the Johnson (BVR J I J JHK), Cousins (R C I C ), Kron (R K I K ), Sloan (griz), and WISE (W 3 W 4 ) photometric systems. These relations have an average standard deviation of ∼3% and are valid for stars with spectral types A0-M4. To derive even more accurate relations for Sun-like stars, we also determined these temperature relations omitting early-type stars (T eff > 6750 K) that may have biased luminosity estimates because of rapid rotation; for this subset the dispersion is only ∼2.5%. We find effective temperatures in agreement within a couple of percent for the interferometrically characterized sample of main-sequence stars compared to those derived via the infrared flux method and spectroscopic analysis.

Solar-Type Activity in Main-Sequence Stars

CERN Document Server

Gershberg, Roald E

2005-01-01

Solar-type activity over the whole range of the electromagnetic spectrum is a phenomenon inherent in the majority of low- and moderate-mass main sequence stars. In this monograph observational results are summarized in a systematic and comprehensive fashion. The analysis of the various manifestations of such stellar activity leads to the identification of these phenomena with macroscopic non-linear processes in a magnetized plasma. Comparative study of flare stars and the Sun has become increasingly fruitful and is presently an active field of research involving stellar and solar physicists, experts in plasma physics and high-energy astrophysicists. This book will provide them with both an introduction and overview of observational results from the first optical photometry and spectroscopy, from the satellite telescopes International Ultraviolet Explorer to Hubble Space Telescope, XMM-Newton and Chandra, as well as with the present physical interpretation of solar-type activity in main sequence stars. Gershbe...

On the Roche constants for main-sequence binaries

International Nuclear Information System (INIS)

Giannuzzi, M.A.

1979-01-01

The ratios C 1 /C 2 of the constants defining the equipotential surfaces which describe the external forms of the components of a close binary system have been calculated on the basis of evolutionary models. Theoretical systems have been considered allowing for a wide range of input parameters (masses and separation) and taking into account the evolutionary effects on the radii of the stars during their Main-Sequence lifetime. The systems have not undergone any transfer of matter and are representative of detached binaries with Main-sequence components. The ratios of the constants are confined in limited intervals and, for the highest values of the mass-ratios, they are clustered around the unit. (Auth.)

On the Statistical Properties of the Lower Main Sequence

International Nuclear Information System (INIS)

Angelou, George C.; Bellinger, Earl P.; Hekker, Saskia; Basu, Sarbani

2017-01-01

Astronomy is in an era where all-sky surveys are mapping the Galaxy. The plethora of photometric, spectroscopic, asteroseismic, and astrometric data allows us to characterize the comprising stars in detail. Here we quantify to what extent precise stellar observations reveal information about the properties of a star, including properties that are unobserved, or even unobservable. We analyze the diagnostic potential of classical and asteroseismic observations for inferring stellar parameters such as age, mass, and radius from evolutionary tracks of solar-like oscillators on the lower main sequence. We perform rank correlation tests in order to determine the capacity of each observable quantity to probe structural components of stars and infer their evolutionary histories. We also analyze the principal components of classic and asteroseismic observables to highlight the degree of redundancy present in the measured quantities and demonstrate the extent to which information of the model parameters can be extracted. We perform multiple regression using combinations of observable quantities in a grid of evolutionary simulations and appraise the predictive utility of each combination in determining the properties of stars. We identify the combinations that are useful and provide limits to where each type of observable quantity can reveal information about a star. We investigate the accuracy with which targets in the upcoming TESS and PLATO missions can be characterized. We demonstrate that the combination of observations from GAIA and PLATO will allow us to tightly constrain stellar masses, ages, and radii with machine learning for the purposes of Galactic and planetary studies.

On the Statistical Properties of the Lower Main Sequence

Energy Technology Data Exchange (ETDEWEB)

Angelou, George C.; Bellinger, Earl P.; Hekker, Saskia [Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany); Basu, Sarbani [Department of Astronomy, Yale University, New Haven, CT 06520 (United States)

2017-04-20

Astronomy is in an era where all-sky surveys are mapping the Galaxy. The plethora of photometric, spectroscopic, asteroseismic, and astrometric data allows us to characterize the comprising stars in detail. Here we quantify to what extent precise stellar observations reveal information about the properties of a star, including properties that are unobserved, or even unobservable. We analyze the diagnostic potential of classical and asteroseismic observations for inferring stellar parameters such as age, mass, and radius from evolutionary tracks of solar-like oscillators on the lower main sequence. We perform rank correlation tests in order to determine the capacity of each observable quantity to probe structural components of stars and infer their evolutionary histories. We also analyze the principal components of classic and asteroseismic observables to highlight the degree of redundancy present in the measured quantities and demonstrate the extent to which information of the model parameters can be extracted. We perform multiple regression using combinations of observable quantities in a grid of evolutionary simulations and appraise the predictive utility of each combination in determining the properties of stars. We identify the combinations that are useful and provide limits to where each type of observable quantity can reveal information about a star. We investigate the accuracy with which targets in the upcoming TESS and PLATO missions can be characterized. We demonstrate that the combination of observations from GAIA and PLATO will allow us to tightly constrain stellar masses, ages, and radii with machine learning for the purposes of Galactic and planetary studies.

ULTRAVIOLET-SELECTED FIELD AND PRE-MAIN-SEQUENCE STARS TOWARD TAURUS AND UPPER SCORPIUS

International Nuclear Information System (INIS)

Findeisen, K.; Hillenbrand, L.

2010-01-01

We have carried out a Galaxy Evolution Explorer (GALEX) Cycle 1 guest investigator program covering 56 deg 2 near the Taurus T association and 12 deg 2 along the northern edge of the Upper Scorpius OB association. We combined photometry in the GALEX far-ultraviolet and near-ultraviolet bands with data from the Two Micron All Sky Survey to identify candidate young (∼<100 Myr old) stars as those with an ultraviolet excess relative to older main-sequence stars. Follow-up spectroscopy of a partial sample of these candidates suggests five new members of Taurus, with 8-20 expected from additional observations, and five new members of Upper Scorpius, with three to six expected from additional observations. These candidate new members appear to represent a distributed, non-clustered population in either region, although our sample statistics are as of yet too poor to constrain the nature or extent of this population. Rather, our study demonstrates the ability of GALEX observations to identify young stellar populations distributed over a wide area of the sky. We also highlight the necessity of a better understanding of the Galactic ultraviolet source population to support similar investigations. In particular, we report a large population of stars with an ultraviolet excess but no optical indicators of stellar activity or accretion, and briefly argue against several interpretations of these sources.

AN OBJECTIVE DEFINITION FOR THE MAIN SEQUENCE OF STAR-FORMING GALAXIES

Energy Technology Data Exchange (ETDEWEB)

Renzini, Alvio [INAF—Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, I-35122 Padova (Italy); Peng, Ying-jie, E-mail: alvio.renzini@oapd.inaf.it, E-mail: y.peng@mrao.cam.ac.uk [Cavendish Laboratory, University of Cambridge, 19 J. J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom)

2015-03-10

The main sequence (MS) of star-forming (SF) galaxies plays a fundamental role in driving galaxy evolution and our efforts to understand it. However, different studies find significant differences in the normalization, slope, and shape of the MS. These discrepancies arise mainly from the different selection criteria adopted to isolate SF galaxies, which may include or exclude galaxies with a specific star formation rate (SFR) substantially below the MS value. To obviate this limitation of all current criteria, we propose an objective definition of the MS that does not rely at all on a pre-selection of SF galaxies. Constructing the 3D SFR–mass–number plot, the MS is then defined as the ridge line of the SF peak, as illustrated with various figures. The advantages of such a definition are manifold. If generally adopted, it will facilitate the inter-comparison of results from different groups using the same SFR and stellar mass diagnostics, or it will highlight the relative systematics of different diagnostics. All of this could help to understand MS galaxies as systems in a quasi-steady state equilibrium and would also provide a more objective criterion for identifying quenching galaxies.

AN OBJECTIVE DEFINITION FOR THE MAIN SEQUENCE OF STAR-FORMING GALAXIES

International Nuclear Information System (INIS)

Renzini, Alvio; Peng, Ying-jie

2015-01-01

The main sequence (MS) of star-forming (SF) galaxies plays a fundamental role in driving galaxy evolution and our efforts to understand it. However, different studies find significant differences in the normalization, slope, and shape of the MS. These discrepancies arise mainly from the different selection criteria adopted to isolate SF galaxies, which may include or exclude galaxies with a specific star formation rate (SFR) substantially below the MS value. To obviate this limitation of all current criteria, we propose an objective definition of the MS that does not rely at all on a pre-selection of SF galaxies. Constructing the 3D SFR–mass–number plot, the MS is then defined as the ridge line of the SF peak, as illustrated with various figures. The advantages of such a definition are manifold. If generally adopted, it will facilitate the inter-comparison of results from different groups using the same SFR and stellar mass diagnostics, or it will highlight the relative systematics of different diagnostics. All of this could help to understand MS galaxies as systems in a quasi-steady state equilibrium and would also provide a more objective criterion for identifying quenching galaxies

The Star-forming Main Sequence of Dwarf Low Surface Brightness Galaxies

Science.gov (United States)

McGaugh, Stacy S.; Schombert, James M.; Lelli, Federico

2017-12-01

We explore the star-forming properties of late-type, low surface brightness (LSB) galaxies. The star-forming main sequence ({SFR}-{M}* ) of LSB dwarfs has a steep slope, indistinguishable from unity (1.04 ± 0.06). They form a distinct sequence from more massive spirals, which exhibit a shallower slope. The break occurs around {M}* ≈ {10}10 {M}⊙ , and can also be seen in the gas mass—stellar mass plane. The global Kennicutt-Schmidt law ({SFR}-{M}g) has a slope of 1.47 ± 0.11 without the break seen in the main sequence. There is an ample supply of gas in LSB galaxies, which have gas depletion times well in excess of a Hubble time, and often tens of Hubble times. Only ˜ 3 % of this cold gas needs be in the form of molecular gas to sustain the observed star formation. In analogy with the faint, long-lived stars of the lower stellar main sequence, it may be appropriate to consider the main sequence of star-forming galaxies to be defined by thriving dwarfs (with {M}* {10}10 {M}⊙ ) are weary giants that constitute more of a turn-off population.

Lithium abundances and metallicities in stars near the main-sequence turnoff and a giant in M67

International Nuclear Information System (INIS)

Garcia Lopez, R.J.; Rebolo, R.; Beckman, J.E.

1988-01-01

The iron abundance of seven stars near the main-sequence (MS) turnoff and a giant in M67 are spectroscopically derived, and the results are discussed. The resulting mean iron abundance of the turnoff stars is (Fe/H) = 0.04 + or - 0.04. Taken together with previous determinations for younger clusters, this shows that there has been relatively little change of the iron abundance in the solar neighborhood during the last 5 Gyr. Lithium was detected in one unevolved star and marginally in the giant, while in the other MS stars only upper limits were found. The considerable differences in Li abundances for stars with similar surface temperature imply that there is at least one parameter affecting Li depletion apart from stellar mass and metallicity. Nonsimultaneous star formation in the cluster cloud explain the scatter in lithium abundances. 50 references

STELLAR DIAMETERS AND TEMPERATURES. III. MAIN-SEQUENCE A, F, G, AND K STARS: ADDITIONAL HIGH-PRECISION MEASUREMENTS AND EMPIRICAL RELATIONS

Energy Technology Data Exchange (ETDEWEB)

Boyajian, Tabetha S.; Jones, Jeremy; White, Russel; McAlister, Harold A.; Gies, Douglas [Center for High Angular Resolution Astronomy and Department of Physics and Astronomy, Georgia State University, P.O. Box 4106, Atlanta, GA 30302-4106 (United States); Von Braun, Kaspar [NASA Exoplanet Science Institute, California Institute of Technology, MC 100-22, Pasadena, CA 91125 (United States); Van Belle, Gerard [Lowell Observatory, Flagstaff, AZ 86001 (United States); Farrington, Chris; Schaefer, Gail; Ten Brummelaar, Theo A.; Sturmann, Laszlo; Sturmann, Judit; Turner, Nils H.; Goldfinger, P. J.; Vargas, Norm [CHARA Array, Mount Wilson Observatory, Mount Wilson, CA 91023 (United States); Ridgway, Stephen [National Optical Astronomy Observatory, P.O. Box 26732, Tucson, AZ 85726-6732 (United States)

2013-07-01

Based on CHARA Array measurements, we present the angular diameters of 23 nearby, main-sequence stars, ranging from spectral types A7 to K0, 5 of which are exoplanet host stars. We derive linear radii, effective temperatures, and absolute luminosities of the stars using Hipparcos parallaxes and measured bolometric fluxes. The new data are combined with previously published values to create an Angular Diameter Anthology of measured angular diameters to main-sequence stars (luminosity classes V and IV). This compilation consists of 125 stars with diameter uncertainties of less than 5%, ranging in spectral types from A to M. The large quantity of empirical data is used to derive color-temperature relations to an assortment of color indices in the Johnson (BVR{sub J} I{sub J} JHK), Cousins (R{sub C} I{sub C}), Kron (R{sub K} I{sub K}), Sloan (griz), and WISE (W{sub 3} W{sub 4}) photometric systems. These relations have an average standard deviation of {approx}3% and are valid for stars with spectral types A0-M4. To derive even more accurate relations for Sun-like stars, we also determined these temperature relations omitting early-type stars (T{sub eff} > 6750 K) that may have biased luminosity estimates because of rapid rotation; for this subset the dispersion is only {approx}2.5%. We find effective temperatures in agreement within a couple of percent for the interferometrically characterized sample of main-sequence stars compared to those derived via the infrared flux method and spectroscopic analysis.

The evolution of coronal activity in main sequence cool stars

International Nuclear Information System (INIS)

Stern, R.A.

1984-01-01

Stars spend most of their lifetime and show the least amount of nuclear evolution on the main sequence. However, the x-ray luminosities of cool star coronas change by orders of magnitude as a function of main sequence age. Such coronal evolution is discussed in relation to our knowledge of the solar corona, solar and stellar flares, stellar rotation and binarity. The relevance of X-ray observations to current speculations on stellar dynamos is also considered

Post-main-sequence planetary system evolution

Science.gov (United States)

Veras, Dimitri

2016-01-01

The fates of planetary systems provide unassailable insights into their formation and represent rich cross-disciplinary dynamical laboratories. Mounting observations of post-main-sequence planetary systems necessitate a complementary level of theoretical scrutiny. Here, I review the diverse dynamical processes which affect planets, asteroids, comets and pebbles as their parent stars evolve into giant branch, white dwarf and neutron stars. This reference provides a foundation for the interpretation and modelling of currently known systems and upcoming discoveries. PMID:26998326

A Constraint on the Formation Timescale of the Young Open Cluster NGC 2264: Lithium Abundance of Pre-main Sequence Stars

Science.gov (United States)

Lim, Beomdu; Sung, Hwankyung; Kim, Jinyoung S.; Bessell, Michael S.; Hwang, Narae; Park, Byeong-Gon

2016-11-01

The timescale of cluster formation is an essential parameter in order to understand the formation process of star clusters. Pre-main sequence (PMS) stars in nearby young open clusters reveal a large spread in brightness. If the spread were considered to be a result of a real spread in age, the corresponding cluster formation timescale would be about 5-20 Myr. Hence it could be interpreted that star formation in an open cluster is prolonged for up to a few tens of Myr. However, difficulties in reddening correction, observational errors, and systematic uncertainties introduced by imperfect evolutionary models for PMS stars can result in an artificial age spread. Alternatively, we can utilize Li abundance as a relative age indicator of PMS star to determine the cluster formation timescale. The optical spectra of 134 PMS stars in NGC 2264 have been obtained with MMT/Hectochelle. The equivalent widths have been measured for 86 PMS stars with a detectable Li line (3500\\lt {T}{eff}[{{K}}]≤slant 6500). Li abundance under the condition of local thermodynamic equilibrium (LTE) was derived using the conventional curve of growth method. After correction for non-LTE effects, we find that the initial Li abundance of NGC 2264 is A({Li})=3.2+/- 0.2. From the distribution of the Li abundances, the underlying age spread of the visible PMS stars is estimated to be about 3-4 Myr and this, together with the presence of embedded populations in NGC 2264, suggests that the cluster formed on a timescale shorter than 5 Myr.

Photometric Determination of the Mass Accretion Rates of Pre-main-sequence Stars. V. Recent Star Formation in the 30 Dor Nebula

Science.gov (United States)

De Marchi, Guido; Panagia, Nino; Beccari, Giacomo

2017-09-01

We report on the properties of the low-mass stars that recently formed in the central ˜ 2\\buildrel{ \\prime}\\over{.} 7× 2\\buildrel{ \\prime}\\over{.} 7 of 30 Dor, including the R136 cluster. Using the photometric catalog of De Marchi et al., based on observations with the Hubble Space Telescope, and the most recent extinction law for this field, we identify 1035 bona fide pre-main-sequence (PMS) stars showing {{H}}α excess emission at the 4σ level with an {{H}}α equivalent width of 20 Å or more. We find a wide spread in age spanning the range ˜ 0.1{--}50 {Myr}. We also find that the older PMS objects are placed in front of the R136 cluster and are separated from it by a conspicuous amount of absorbing material, indicating that star formation has proceeded from the periphery into the interior of the region. We derive physical parameters for all PMS stars, including masses m, ages t, and mass accretion rates {\\dot{M}}{acc}. To identify reliable correlations between these parameters, which are intertwined, we use a multivariate linear regression fit of the type {log}{\\dot{M}}{acc}=a× {log}t+b× {log}m+c. The values of a and b for 30 Dor are compatible with those found in NGC 346 and NGC 602. We extend the fit to a uniform sample of 1307 PMS stars with 0.5contract NAS5-26555.

IRAS 18153-1651: an H II region with a possible wind bubble blown by a young main-sequence B star

Science.gov (United States)

Gvaramadze, V. V.; Mackey, J.; Kniazev, A. Y.; Langer, N.; Chené, A.-N.; Castro, N.; Haworth, T. J.; Grebel, E. K.

2017-04-01

We report the results of spectroscopic observations and numerical modelling of the H II region IRAS 18153-1651. Our study was motivated by the discovery of an optical arc and two main-sequence stars of spectral type B1 and B3 near the centre of IRAS 18153-1651. We interpret the arc as the edge of the wind bubble (blown by the B1 star), whose brightness is enhanced by the interaction with a photoevaporation flow from a nearby molecular cloud. This interpretation implies that we deal with a unique case of a young massive star (the most massive member of a recently formed low-mass star cluster) caught just tens of thousands of years after its stellar wind has begun to blow a bubble into the surrounding dense medium. Our 2D, radiation-hydrodynamics simulations of the wind bubble and the H II region around the B1 star provide a reasonable match to observations, both in terms of morphology and absolute brightness of the optical and mid-infrared emission, and verify the young age of IRAS 18153-1651. Taken together our results strongly suggest that we have revealed the first example of a wind bubble blown by a main-sequence B star.

Three aspects of stellar evolution near the main sequence

International Nuclear Information System (INIS)

Morgan, J.C.

1979-05-01

Three problems of stellar evolution are considered: the gap in the HR diagram of M67, the evolutionary status of RS CVn binaries and the solar neutrino problem. The physical basis of the Eggleton stellar evolution computer program is described. The program was used to calculate a grid of evolutionary tracks for models with masses between 0.7 and 1.29 solar masses. The more massive stars considered here have expanding convective cores during their main sequence evolution. The isochrone of the old galactic cluster M67 has a gap at the top of its main sequence because of the rapid evolution of stars at hydrogen exhaustion. RS CVn binaries present a complex collection of observational phenomena although they appear to be detached binaries. Their evolutionary status has remained controversial because of their high space density. Here it is shown that a post main sequence interpretation is satisfactory. Models of the Sun with metal poor interiors have been proposed in an attempt to resolve the solar neutrino problem. Here the evolution of two such models is calculated in detail, including a gradual contamination of the surface convection zone to produce the observed metal abundance, giving fully consistent models of the Sun as it is observed. (author)

Constraining the magnitude of the largest event in a foreshock-main shock-aftershock sequence

Science.gov (United States)

Shcherbakov, Robert; Zhuang, Jiancang; Ogata, Yosihiko

2018-01-01

Extreme value statistics and Bayesian methods are used to constrain the magnitudes of the largest expected earthquakes in a sequence governed by the parametric time-dependent occurrence rate and frequency-magnitude statistics. The Bayesian predictive distribution for the magnitude of the largest event in a sequence is derived. Two types of sequences are considered, that is, the classical aftershock sequences generated by large main shocks and the aftershocks generated by large foreshocks preceding a main shock. For the former sequences, the early aftershocks during a training time interval are used to constrain the magnitude of the future extreme event during the forecasting time interval. For the latter sequences, the earthquakes preceding the main shock are used to constrain the magnitudes of the subsequent extreme events including the main shock. The analysis is applied retrospectively to past prominent earthquake sequences.

Effects of main-sequence mass loss on stellar and galactic chemical evolution

International Nuclear Information System (INIS)

Guzik, J.A.

1988-01-01

L.A. Willson, G.H. Bowen and C. Struck-Marcell have proposed that 1 to 3 solar mass stars may experience evolutionarily significant mass loss during the early part of their main-sequence phase. The suggested mass-loss mechanism is pulsation, facilitated by rapid rotation. Initial mass-loss rates may be as large as several times 10 -9 M mass of sun/yr, diminishing over several times 10 8 years. The author attempts to test this hypothesis by comparing some theoretical implications with observations. Three areas are addressed: Solar models, cluster HR diagrams, and galactic chemical evolution. Mass-losing solar models were evolved that match the Sun's luminosity and radius at its present age. The most extreme viable models have initial mass 2.0 M 0 , and mass-loss rates decreasing exponentially over 2-3 x 10 8 years. Evolution calculations incorporating main-sequence mass loss were completed for a grid of models with initial masses 1.25 to 2.0 M mass of sun and mass loss timescales 0.2 to 2.0 Gry. Cluster HR diagrams synthesized with these models confirm the potential for the hypothesis to explain observed spreads or bifurcations in the upper main sequence, blue stragglers, anomalous giants, and poor fits of main-sequence turnoffs by standard isochrones. Simple closed galactic chemical evolution models were used to test the effects of main-sequence mass loss on the F and G dwarf distribution. Stars between 3.0 M mass of sun and a metallicity-dependent lower mass are assumed to lose mass. The models produce a 30 to 60% increase in the stars to stars-plus-remnants ratio, with fewer early-F dwarfs and many more late-F dwarfs remaining on the main sequence to the present

Evolution Models of Helium White Dwarf–Main-sequence Star Merger Remnants

International Nuclear Information System (INIS)

Zhang, Xianfei; Bi, Shaolan; Hall, Philip D.; Jeffery, C. Simon

2017-01-01

It is predicted that orbital decay by gravitational-wave radiation and tidal interaction will cause some close binary stars to merge within a Hubble time. The merger of a helium-core white dwarf with a main-sequence (MS) star can produce a red giant branch star that has a low-mass hydrogen envelope when helium is ignited and thus become a hot subdwarf. Because detailed calculations have not been made, we compute post-merger models with a stellar evolution code. We find the evolutionary paths available to merger remnants and find the pre-merger conditions that lead to the formation of hot subdwarfs. We find that some such mergers result in the formation of stars with intermediate helium-rich surfaces. These stars later develop helium-poor surfaces owing to diffusion. Combining our results with a model population and comparing to observed stars, we find that some observed intermediate helium-rich hot subdwarfs can be explained as the remnants of the mergers of helium-core white dwarfs with low-mass MS stars.

Evolution Models of Helium White Dwarf–Main-sequence Star Merger Remnants

Energy Technology Data Exchange (ETDEWEB)

Zhang, Xianfei; Bi, Shaolan [Department of Astronomy, Beijing Normal University, Beijing, 100875 (China); Hall, Philip D.; Jeffery, C. Simon, E-mail: zxf@bnu.edu.cn [Armagh Observatory, College Hill, Armagh BT61 9DG (United Kingdom)

2017-02-01

It is predicted that orbital decay by gravitational-wave radiation and tidal interaction will cause some close binary stars to merge within a Hubble time. The merger of a helium-core white dwarf with a main-sequence (MS) star can produce a red giant branch star that has a low-mass hydrogen envelope when helium is ignited and thus become a hot subdwarf. Because detailed calculations have not been made, we compute post-merger models with a stellar evolution code. We find the evolutionary paths available to merger remnants and find the pre-merger conditions that lead to the formation of hot subdwarfs. We find that some such mergers result in the formation of stars with intermediate helium-rich surfaces. These stars later develop helium-poor surfaces owing to diffusion. Combining our results with a model population and comparing to observed stars, we find that some observed intermediate helium-rich hot subdwarfs can be explained as the remnants of the mergers of helium-core white dwarfs with low-mass MS stars.

Central limit theorems for sequences with m(n)-dependent main part

NARCIS (Netherlands)

Nieuwenhuis, G.

1992-01-01

Let (Xi(n); n ϵ N, 1⩽i⩽h(n)) be a double sequence of random variables with h(n)→∞ as n→∞. Suppose that the sequence can be split into two parts: an m(n)-dependent sequence (Xi,m(n); n ϵ N, 1⩽i⩽h(n)) of main terms and a sequence (Xi,m(n); n ϵ N, 1⩽i⩽h(n)) of residual terms. Here (m(n)) may be

Domain general sequence operations contribute to pre-SMA involvement in visuo-spatial processing

Directory of Open Access Journals (Sweden)

E. Charles eLeek

2016-01-01

Full Text Available This study used 3T MRI to elucidate the functional role of supplementary motor area (SMA in relation to visuo-spatial processing. A localizer task contrasting sequential number subtraction and repetitive button pressing was used to functionally delineate non-motor sequence processing in pre-SMA, and activity in SMA-proper associated with motor sequencing. Patterns of BOLD responses in these regions were then contrasted to those from two tasks of visuo-spatial processing. In one task participants performed mental rotation in which recognition memory judgments were made to previously memorized 2D novel patterns across image-plane rotations. The other task involved abstract grid navigation in which observers computed a series of imagined location shifts in response to directional (arrow cues around a mental grid. The results showed overlapping activation in pre-SMA for sequential subtraction and both visuo-spatial tasks. These results suggest that visuo-spatial processing is supported by non-motor sequence operations that involve pre-SMA. More broadly, these data further highlight the functional heterogeneity of pre-SMA, and show that its role extends to processes beyond the planning and online control of movement.

A M2FS Spectroscopic Study of Low-mass Young Stars in Orion OB1

Science.gov (United States)

Kaleida, Catherine C.; Briceno, Cesar; Calvet, Nuria; Mateo, Mario L.; Hernandez, Jesus

2015-01-01

Surveys of pre-main sequence stars in the ~4-10 Myr range provide a window into the decline of the accretion phase of stars and the formation of planets. Nearby star clusters and stellar associations allow for the study of these young stellar populations all the way down to the lowest mass members. One of the best examples of nearby 4-10 Myr old stellar populations is the Orion OB1 association. The CIDA Variability Survey of Orion OB1 (CVSO - Briceño et al. 2001) has used the variability properties of low-mass pre-main-sequence (PMS) stars to identify hundreds of K and M-type stellar members of the Orion OB1 association, a number of them displaying IR-excess emission and thought to be representative of more evolved disk-bearing young stars. Characterizing these young, low-mass objects using spectroscopy is integral to understanding the accretion phase in young stars. We present preliminary results of a spectroscopic survey of candidate and confirmed Orion OB1 low-mass members taken during November 2014 and February 2014 using the Michigan/Magellan Fiber Spectrograph (M2FS), a PI instrument on the Magellan Clay Telescope (PI: M. Matteo). Target fields located in the off-cloud regions of Orion were identified in the CVSO, and observed using the low and high-resolution modes of M2FS. Both low and high-resolution spectra are needed in order to confirm membership and derive masses, ages, kinematics and accretion properties. Initial analysis of these spectra reveal many new K and M-type members of the Orion OB1 association in these low extinction, off-cloud areas. These are the more evolved siblings of the youngest stars still embedded in the molecular clouds, like those in the Orion Nebula Cluster. With membership and spectroscopic indicators of accretion we are building the most comprehensive stellar census of this association, enabling us to derive a robust estimate of the fraction of young stars still accreting at a various ages, a key constraint for the end of

White dwarf-main sequence binaries from LAMOST: the DR5 catalogue

Science.gov (United States)

Ren, J.-J.; Rebassa-Mansergas, A.; Parsons, S. G.; Liu, X.-W.; Luo, A.-L.; Kong, X.; Zhang, H.-T.

2018-03-01

We present the data release (DR) 5 catalogue of white dwarf-main sequence (WDMS) binaries from the Large Area Multi-Object fiber Spectroscopic Telescope (LAMOST). The catalogue contains 876 WDMS binaries, of which 757 are additions to our previous LAMOST DR1 sample and 357 are systems that have not been published before. We also describe a LAMOST-dedicated survey that aims at obtaining spectra of photometrically-selected WDMS binaries from the Sloan Digital Sky Survey (SDSS) that are expected to contain cool white dwarfs and/or early type M dwarf companions. This is a population under-represented in previous SDSS WDMS binary catalogues. We determine the stellar parameters (white dwarf effective temperatures, surface gravities and masses, and M dwarf spectral types) of the LAMOST DR5 WDMS binaries and make use of the parameter distributions to analyse the properties of the sample. We find that, despite our efforts, systems containing cool white dwarfs remain under-represented. Moreover, we make use of LAMOST DR5 and SDSS DR14 (when available) spectra to measure the Na I λλ 8183.27, 8194.81 absorption doublet and/or Hα emission radial velocities of our systems. This allows identifying 128 binaries displaying significant radial velocity variations, 76 of which are new. Finally, we cross-match our catalogue with the Catalina Surveys and identify 57 systems displaying light curve variations. These include 16 eclipsing systems, two of which are new, and nine binaries that are new eclipsing candidates. We calculate periodograms from the photometric data and measure (estimate) the orbital periods of 30 (15) WDMS binaries.

Evolution models of helium white dwarf-main-sequence star merger remnants: the mass distribution of single low-mass white dwarfs

Science.gov (United States)

Zhang, Xianfei; Hall, Philip D.; Jeffery, C. Simon; Bi, Shaolan

2018-02-01

It is not known how single white dwarfs with masses less than 0.5Msolar -- low-mass white dwarfs -- are formed. One way in which such a white dwarf might be formed is after the merger of a helium-core white dwarf with a main-sequence star that produces a red giant branch star and fails to ignite helium. We use a stellar-evolution code to compute models of the remnants of these mergers and find a relation between the pre-merger masses and the final white dwarf mass. Combining our results with a model population, we predict that the mass distribution of single low-mass white dwarfs formed through this channel spans the range 0.37 to 0.5Msolar and peaks between 0.45 and 0.46Msolar. Helium white dwarf--main-sequence star mergers can also lead to the formation of single helium white dwarfs with masses up to 0.51Msolar. In our model the Galactic formation rate of single low-mass white dwarfs through this channel is about 8.7X10^-3yr^-1. Comparing our models with observations, we find that the majority of single low-mass white dwarfs (<0.5Msolar) are formed from helium white dwarf--main-sequence star mergers, at a rate which is about $2$ per cent of the total white dwarf formation rate.

Reconciling mass functions with the star-forming main sequence via mergers

Science.gov (United States)

Steinhardt, Charles L.; Yurk, Dominic; Capak, Peter

2017-06-01

We combine star formation along the 'main sequence', quiescence and clustering and merging to produce an empirical model for the evolution of individual galaxies. Main-sequence star formation alone would significantly steepen the stellar mass function towards low redshift, in sharp conflict with observation. However, a combination of star formation and merging produces a consistent result for correct choice of the merger rate function. As a result, we are motivated to propose a model in which hierarchical merging is disconnected from environmentally independent star formation. This model can be tested via correlation functions and would produce new constraints on clustering and merging.

Effects of Main-Sequence Mass Loss on Stellar and Galactic Chemical Evolution.

Science.gov (United States)

Guzik, Joyce Ann

1988-06-01

L. A. Willson, G. H. Bowen and C. Struck -Marcell have proposed that 1 to 3 solar mass stars may experience evolutionarily significant mass loss during the early part of their main-sequence phase. The suggested mass-loss mechanism is pulsation, facilitated by rapid rotation. Initial mass-loss rates may be as large as several times 10^{-9}M o/yr, diminishing over several times 10^8 years. We attempted to test this hypothesis by comparing some theoretical implications with observations. Three areas are addressed: Solar models, cluster HR diagrams, and galactic chemical evolution. Mass-losing solar models were evolved that match the Sun's luminosity and radius at its present age. The most extreme viable models have initial mass 2.0 M o, and mass-loss rates decreasing exponentially over 2-3 times 10^8 years. Compared to a constant -mass model, these models require a reduced initial ^4He abundance, have deeper envelope convection zones and higher ^8B neutrino fluxes. Early processing of present surface layers at higher interior temperatures increases the surface ^3He abundance, destroys Li, Be and B, and decreases the surface C/N ratio following first dredge-up. Evolution calculations incorporating main-sequence mass loss were completed for a grid of models with initial masses 1.25 to 2.0 Mo and mass loss timescales 0.2 to 2.0 Gyr. Cluster HR diagrams synthesized with these models confirm the potential for the hypothesis to explain observed spreads or bifurcations in the upper main sequence, blue stragglers, anomalous giants, and poor fits of main-sequence turnoffs by standard isochrones. Simple closed galactic chemical evolution models were used to test the effects of main-sequence mass loss on the F and G dwarf distribution. Stars between 3.0 M o and a metallicity -dependent lower mass are assumed to lose mass. The models produce a 30 to 60% increase in the stars to stars-plus -remnants ratio, with fewer early-F dwarfs and many more late-F dwarfs remaining on the main

Effects of mass loss on the evolution of massive stars. I. Main-sequence evolution

International Nuclear Information System (INIS)

Dearborn, D.S.P.; Blake, J.B.; Hainebach, K.L.; Schramm, D.N.

1978-01-01

The effect of mass loss on the evolution and surface composition of massive stars during main-sequence evolution are examined. While some details of the evolutionary track depend on the formula used for the mass loss, the results appear most sensitive to the total mass removed during the main-sequence lifetime. It was found that low mass-loss rates have very little effect on the evolution of a star; the track is slightly subluminous, but the lifetime is almost unaffected. High rates of mass loss lead to a hot, high-luminosity stellar model with a helium core surrounded by a hydrogen-deficient (Xapprox.0.1) envelope. The main-sequence lifetime is extended by a factor of 2--3. These models may be identified with Wolf-Rayet stars. Between these mass-loss extremes are intermediate models which appear as OBN stars on the main sequence. The mass-loss rates required for significant observable effects range from 8 x 10 -7 to 10 -5 M/sub sun/ yr -1 , depending on the initial stellar mass. It is found that observationally consistent mass-loss rates for stars with M> or =30 M/sub sun/ may be sufficiently high that these stars lose mass on a time scale more rapidly than their main-sequence core evolution time. This result implies that the helium cores resulting from the main-sequence evolution of these massive stars may all be very similar to that of a star of Mapprox.30 M/sub sun/ regardless of the zero-age mass

THE CLUSTERED NATURE OF STAR FORMATION. PRE-MAIN-SEQUENCE CLUSTERS IN THE STAR-FORMING REGION NGC 602/N90 IN THE SMALL MAGELLANIC CLOUD

International Nuclear Information System (INIS)

Gouliermis, Dimitrios A.; Gennaro, Mario; Schmeja, Stefan; Dolphin, Andrew E.; Tognelli, Emanuele; Prada Moroni, Pier Giorgio

2012-01-01

Located at the tip of the wing of the Small Magellanic Cloud (SMC), the star-forming region NGC 602/N90 is characterized by the H II nebular ring N90 and the young cluster of pre-main-sequence (PMS) and early-type main-sequence stars NGC 602, located in the central area of the ring. We present a thorough cluster analysis of the stellar sample identified with Hubble Space Telescope/Advanced Camera for Surveys in the region. We show that apart from the central cluster low-mass PMS stars are congregated in 13 additional small, compact sub-clusters at the periphery of NGC 602, identified in terms of their higher stellar density with respect to the average background density derived from star counts. We find that the spatial distribution of the PMS stars is bimodal, with an unusually large fraction (∼60%) of the total population being clustered, while the remaining is diffusely distributed in the intercluster area, covering the whole central part of the region. From the corresponding color-magnitude diagrams we disentangle an age difference of ∼2.5 Myr between NGC 602 and the compact sub-clusters, which appear younger, on the basis of comparison of the brighter PMS stars with evolutionary models, which we accurately calculated for the metal abundance of the SMC. The diffuse PMS population appears to host stars as old as those in NGC 602. Almost all detected PMS sub-clusters appear to be centrally concentrated. When the complete PMS stellar sample, including both clustered and diffused stars, is considered in our cluster analysis, it appears as a single centrally concentrated stellar agglomeration, covering the whole central area of the region. Considering also the hot massive stars of the system, we find evidence that this agglomeration is hierarchically structured. Based on our findings, we propose a scenario according to which the region NGC 602/N90 experiences an active clustered star formation for the last ∼5 Myr. The central cluster NGC 602 was formed first

A Multi-Fiber Spectroscopic Search for Low-mass Young Stars in Orion OB1

Science.gov (United States)

Loerincs, Jacqueline; Briceno, Cesar; Calvet, Nuria; Mateo, Mario L.; Hernandez, Jesus

2017-01-01

We present here results of a low resolution spectroscopic followup of candidate low-mass pre-main sequence stars in the Orion OB1 association. Our targets were selected from the CIDA Variability Survey of Orion (CVSO), and we used the Michigan/Magellan Fiber Spectrograph (M2FS) on the Magellan Clay 6.5m telescope to obtain spectra of 500 candidate T Tauri stars distributed in seven 0.5 deg diameter fields, adding to a total area of ~5.5 deg2. We identify young stars by looking at the distinctive Hα 6563 Å emission and Lithium Li I 6707 Å absorption features characteristic of young low mass pre-main sequence stars. Furthermore, by measuring the strength of their Hα emission lines, confirmed T Tauri stars can be classified as either Classical T Tauris (CTTS) or Weak-line T Tauris (WTTS), which give indication of whether the star is actively accreting material from a gas and dust disk surrounding the star, which may be the precursor of a planetary system. We confirm a total of 90 T Tauri stars, of which 50% are newly identified young members of Orion; out of the 49 new detections,15 are accreting CTTS, and of these all but one are found in the OB1b sub-region. This result is in line with our previous findings that this region is much younger than the more extended Orion OB1a sub-association. The M2FS results add to our growing census of young stars in Orion, that is allowing us to characterize in a systematic and consistent way the distribution of stellar ages across the entire complex, in order to building a complete picture of star formation in this, one of nearest most active sites of star birth.

Evolution models of helium white dwarf--main-sequence star merger remnants: the mass distribution of single low-mass white dwarfs

OpenAIRE

Zhang, Xianfei; Hall, Philip D.; Jeffery, C. Simon; Bi, Shaolan

2017-01-01

It is not known how single white dwarfs with masses less than 0.5Msolar -- low-mass white dwarfs -- are formed. One way in which such a white dwarf might be formed is after the merger of a helium-core white dwarf with a main-sequence star that produces a red giant branch star and fails to ignite helium. We use a stellar-evolution code to compute models of the remnants of these mergers and find a relation between the pre-merger masses and the final white dwarf mass. Combining our results with ...

The SAMI Galaxy Survey: spatially resolving the main sequence of star formation

Science.gov (United States)

Medling, Anne M.; Cortese, Luca; Croom, Scott M.; Green, Andrew W.; Groves, Brent; Hampton, Elise; Ho, I.-Ting; Davies, Luke J. M.; Kewley, Lisa J.; Moffett, Amanda J.; Schaefer, Adam L.; Taylor, Edward; Zafar, Tayyaba; Bekki, Kenji; Bland-Hawthorn, Joss; Bloom, Jessica V.; Brough, Sarah; Bryant, Julia J.; Catinella, Barbara; Cecil, Gerald; Colless, Matthew; Couch, Warrick J.; Drinkwater, Michael J.; Driver, Simon P.; Federrath, Christoph; Foster, Caroline; Goldstein, Gregory; Goodwin, Michael; Hopkins, Andrew; Lawrence, J. S.; Leslie, Sarah K.; Lewis, Geraint F.; Lorente, Nuria P. F.; Owers, Matt S.; McDermid, Richard; Richards, Samuel N.; Sharp, Robert; Scott, Nicholas; Sweet, Sarah M.; Taranu, Dan S.; Tescari, Edoardo; Tonini, Chiara; van de Sande, Jesse; Walcher, C. Jakob; Wright, Angus

2018-04-01

We present the ˜800 star formation rate maps for the Sydney-AAO Multi-object Integral field spectrograph (SAMI) Galaxy Survey based on H α emission maps, corrected for dust attenuation via the Balmer decrement, that are included in the SAMI Public Data Release 1. We mask out spaxels contaminated by non-stellar emission using the [O III]/H β, [N II]/H α, [S II]/H α, and [O I]/H α line ratios. Using these maps, we examine the global and resolved star-forming main sequences of SAMI galaxies as a function of morphology, environmental density, and stellar mass. Galaxies further below the star-forming main sequence are more likely to have flatter star formation profiles. Early-type galaxies split into two populations with similar stellar masses and central stellar mass surface densities. The main-sequence population has centrally concentrated star formation similar to late-type galaxies, while galaxies >3σ below the main sequence show significantly reduced star formation most strikingly in the nuclear regions. The split populations support a two-step quenching mechanism, wherein halo mass first cuts off the gas supply and remaining gas continues to form stars until the local stellar mass surface density can stabilize the reduced remaining fuel against further star formation. Across all morphologies, galaxies in denser environments show a decreased specific star formation rate from the outside in, supporting an environmental cause for quenching, such as ram-pressure stripping or galaxy interactions.

Fast selection of miRNA candidates based on large-scale pre-computed MFE sets of randomized sequences.

Science.gov (United States)

Warris, Sven; Boymans, Sander; Muiser, Iwe; Noback, Michiel; Krijnen, Wim; Nap, Jan-Peter

2014-01-13

Small RNAs are important regulators of genome function, yet their prediction in genomes is still a major computational challenge. Statistical analyses of pre-miRNA sequences indicated that their 2D structure tends to have a minimal free energy (MFE) significantly lower than MFE values of equivalently randomized sequences with the same nucleotide composition, in contrast to other classes of non-coding RNA. The computation of many MFEs is, however, too intensive to allow for genome-wide screenings. Using a local grid infrastructure, MFE distributions of random sequences were pre-calculated on a large scale. These distributions follow a normal distribution and can be used to determine the MFE distribution for any given sequence composition by interpolation. It allows on-the-fly calculation of the normal distribution for any candidate sequence composition. The speedup achieved makes genome-wide screening with this characteristic of a pre-miRNA sequence practical. Although this particular property alone will not be able to distinguish miRNAs from other sequences sufficiently discriminative, the MFE-based P-value should be added to the parameters of choice to be included in the selection of potential miRNA candidates for experimental verification.

Solar Luminosity on the Main Sequence, Standard Model and Variations

Science.gov (United States)

Ayukov, S. V.; Baturin, V. A.; Gorshkov, A. B.; Oreshina, A. V.

2017-05-01

Our Sun became Main Sequence star 4.6 Gyr ago according Standard Solar Model. At that time solar luminosity was 30% lower than current value. This conclusion is based on assumption that Sun is fueled by thermonuclear reactions. If Earth's albedo and emissivity in infrared are unchanged during Earth history, 2.3 Gyr ago oceans had to be frozen. This contradicts to geological data: there was liquid water 3.6-3.8 Gyr ago on Earth. This problem is known as Faint Young Sun Paradox. We analyze luminosity change in standard solar evolution theory. Increase of mean molecular weight in the central part of the Sun due to conversion of hydrogen to helium leads to gradual increase of luminosity with time on the Main Sequence. We also consider several exotic models: fully mixed Sun; drastic change of pp reaction rate; Sun consisting of hydrogen and helium only. Solar neutrino observations however exclude most non-standard solar models.

THE 'MAIN SEQUENCE' OF EXPLOSIVE SOLAR ACTIVE REGIONS: DISCOVERY AND INTERPRETATION

Energy Technology Data Exchange (ETDEWEB)

Falconer, David A; Moore, Ronald L; Adams, Mitzi [Space Science Office, VP62, Marshall Space Flight Center, Huntsville, AL 35812 (United States); Gary, G. Allen [Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, AL 35899 (United States)], E-mail: David.falconer@msfc.nasa.gov

2009-08-01

We examine the location and distribution of the production of coronal mass ejections (CMEs) and major flares by sunspot active regions in the phase space of two whole-active-region magnetic quantities measured from 1897 SOHO/MDI magnetograms. These magnetograms track the evolution of 44 active regions across the central disk of radius 0.5 R {sub Sun}. The two quantities are {sup L}WL{sub SG}, a gauge of the total free energy in an active region's magnetic field, and {sup L}{phi}, a measure of the active region's total magnetic flux. From these data and each active region's history of production of CMEs, X flares, and M flares, we find (1) that CME/flare-productive active regions are concentrated in a straight-line 'main sequence' in (log {sup L}WL{sub SG}, log {sup L}{phi}) space, (2) that main-sequence active regions have nearly their maximum attainable free magnetic energy, and (3) evidence that this arrangement plausibly results from equilibrium between input of free energy to an explosive active region's magnetic field in the chromosphere and corona by contortion of the field via convection in and below the photosphere and loss of free energy via CMEs, flares, and coronal heating, an equilibrium between energy gain and loss that is analogous to that of the main sequence of hydrogen-burning stars in (mass, luminosity) space.

THE 'MAIN SEQUENCE' OF EXPLOSIVE SOLAR ACTIVE REGIONS: DISCOVERY AND INTERPRETATION

International Nuclear Information System (INIS)

Falconer, David A.; Moore, Ronald L.; Adams, Mitzi; Gary, G. Allen

2009-01-01

We examine the location and distribution of the production of coronal mass ejections (CMEs) and major flares by sunspot active regions in the phase space of two whole-active-region magnetic quantities measured from 1897 SOHO/MDI magnetograms. These magnetograms track the evolution of 44 active regions across the central disk of radius 0.5 R Sun . The two quantities are L WL SG , a gauge of the total free energy in an active region's magnetic field, and L Φ, a measure of the active region's total magnetic flux. From these data and each active region's history of production of CMEs, X flares, and M flares, we find (1) that CME/flare-productive active regions are concentrated in a straight-line 'main sequence' in (log L WL SG , log L Φ) space, (2) that main-sequence active regions have nearly their maximum attainable free magnetic energy, and (3) evidence that this arrangement plausibly results from equilibrium between input of free energy to an explosive active region's magnetic field in the chromosphere and corona by contortion of the field via convection in and below the photosphere and loss of free energy via CMEs, flares, and coronal heating, an equilibrium between energy gain and loss that is analogous to that of the main sequence of hydrogen-burning stars in (mass, luminosity) space.

Binary pulsar PSR 1718-19 contains a stripped main-sequence turn-off star

International Nuclear Information System (INIS)

Zwitter, T.

1993-05-01

Lyne et al. (1993) have recently announced the discovery of a 1-second globular cluster pulsar, 1718-19, in a 6.2-hour binary system which is embedded in a cloud of material originating from the companion star. However the incident flux of the pulsar's radiation on the companion is too low to ablate it and a main sequence companion is too small to fill its Roche lobe. Here I argue that the companion is a stripped turn-off star of 0.2-0.4 solar masses (M sun ) and with approx. 0.1M sun helium core. It has approx. 1.8-times larger radius than a main sequence star of equal mass. Its position in the Hertzsprung-Russell diagram overlaps that of a ∼ 0.65M sun main-sequence star. The evolutionary state of the companion and the highly magnetized slowly rotating neutron star place the system on the verge of the low mass X-ray binary phase. (author). 19 refs, 2 figs

Turbulence and the Li abundance in main sequence and giant stars

International Nuclear Information System (INIS)

Charbonneau, P.; Michaud, G.

1990-01-01

Calculations of Li burning via turbulent transport are conducted to determine the extent to which observed Li abundances in first ascent giants constrain the various turbulence parameterizations used to model the main-sequence surface Li abundance evolution. A full time-dependent solution to the transport equation is performed, including nuclear reaction terms and evolutionary effects. It is found that turbulence can lead to the extreme Li underabundances observed in giants of M67 and NGC 752. Consideration is given to the possibility of using observations of Li abundances to discriminate between turbulent particle transport and meridional circulation transport. Numerical solutions of the turbulent diffusion coefficient of Vauclair (1988) is used to model the Hyades Li abundance gap. The astrophysical implications of the results for main-sequence and giant stars are discussed. 36 refs

Galactic chemical evolution with main-sequence mass loss and the distribution of F and G dwarfs

International Nuclear Information System (INIS)

Guzik, J.A.; Struck-Marcell, C.

1988-01-01

Simple closed galactic chemical-evolution models incorporating early main-sequence stellar mass loss have been developed for disk ages of 5, 10, and 15 Gyr. Relative to models without stellar mass loss, the models are shown to produce a 30-60 percent increase in the present mass ratio of dwarfs to dwarfs plus remnants, and a 200-250 percent increase in the total mass of late F dwarfs remaining on the main sequence at the current disk age. For present disk ages 5 and 10 Gyr, the total mass of mid-F dwarfs remaining on the main sequence is also shown to increase by 90-120 percent. It is concluded that models with main-sequence mass loss have a slightly reduced gas metallicity and slightly increased gas fraction midway through the evolution. 30 references

BVRI main-sequence photometry of the globular cluster M4

International Nuclear Information System (INIS)

Alcaino, G.; Liller, W.

1984-01-01

We present BV and RI photographic photometry of 1421 and 189 stars, respectively, in the intermediate metallicity globular cluster M4 (NGC 6121). This investigation includes the first results of RI main-sequence photometry of a globular cluster. The use of longer wavelengths and longer color baselines provides the potential of improved isochrone fittings and underscores the urgent need for calculations of RI synthetic isochrones to be compared with observations. The Pickering-Racine wedge was used with the ESO 3.6 m telescope, the Las Campanas 2.5 m du Pont telescope, and the CTIO 1 m Yale telescope to extend the photoelectric limit from Vroughly-equal16.1 to Vroughly-equal19.1. We have determined the position of the main-sequence turnoff to lie at V = 16.6 +- 0.2 (m.e.) and B-V = 0.80 +- 0.03 (m.e.). A comparison of our BV observations with the CCD data of Richer and Fahlman shows excellent agreement: the two fifucial main sequences agree at all points to within 0.025 mag and, on average, to 0.013 mag. For the cluster we derive a distance modulus (m-M)/sub V/ = 12.52 +- 0.2 and reddening E(B-V) = 0.44 +- 0.03, results which confirm that at a distance of 2 kpc, M4 is the closest globular clusters to the Sun. Using the isochrones of VandenBerg, we deduce an age 13 +- 2 Gyr. As noted in several other investigations, there is a striking deficiency of stars in certain parts of the color-magnitude diagram; in M4 we find a pronounced gap over approx.0.6 mag at the base of the subgiant branch

DISSECTING THE QUASAR MAIN SEQUENCE: INSIGHT FROM HOST GALAXY PROPERTIES

International Nuclear Information System (INIS)

Sun, Jiayi; Shen, Yue

2015-01-01

The diverse properties of broad-line quasars appear to follow a well-defined main sequence along which the optical Fe ii strength increases. It has been suggested that this sequence is mainly driven by the Eddington ratio (L/L Edd ) of the black hole (BH) accretion. Shen and Ho demonstrated with quasar clustering analysis that the average BH mass decreases with increasing Fe ii strength when quasar luminosity is fixed, consistent with this suggestion. Here we perform an independent test by measuring the stellar velocity dispersion σ * (hence, the BH mass via the M–σ * relation) from decomposed host spectra in low-redshift Sloan Digital Sky Survey quasars. We found that at fixed quasar luminosity, σ * systematically decreases with increasing Fe ii strength, confirming that the Eddington ratio increases with Fe ii strength. We also found that at fixed luminosity and Fe ii strength, there is little dependence of σ * on the broad Hβ FWHM. These new results reinforce the framework that the Eddington ratio and orientation govern most of the diversity seen in broad-line quasar properties

IN-SYNC. VII. Evidence for a Decreasing Spectroscopic Binary Fraction (from 1 to 100 Myr) within the IN-SYNC Sample

Science.gov (United States)

Jaehnig, Karl; Bird, Jonathan C.; Stassun, Keivan G.; Da Rio, Nicola; Tan, Jonathan C.; Cotaar, Michiel; Somers, Garrett

2017-12-01

We study the occurrence of spectroscopic binaries in young star-forming regions using the INfrared Spectroscopy of Young Nebulous Clusters (IN-SYNC) survey, carried out in SDSS-III with the APOGEE spectrograph. Multi-epoch observations of thousands of low-mass stars in Orion A, NGC 2264, NGC 1333, IC 348, and the Pleiades have been carried out, yielding H-band spectra with a nominal resolution of R = 22,500 for sources with H factor of 3-4, from the age of our pre-main-sequence (PMS) sample to the Pleiades age . The significance of this decline is weakened if spot-induced radial-velocity jitter is strong in the sample, and is only marginally significant when comparing any one of the PMS clusters against the Pleiades. However, the same decline in both sense and magnitude is found for each of the five PMS clusters, and the decline reaches a statistical significance of greater than 95% confidence when considering the PMS clusters jointly. Our results suggest that dynamical processes disrupt the widest spectroscopic binaries ({P}{orb}≈ {10}3{--}{10}4 days) as clusters age, indicating that this occurs early in the stars’ evolution, while they still reside within their nascent clusters.

The LAMOST Complete Spectroscopic Survey of Pointing Area (LaCoSSPAr) in the Southern Galactic Cap. I. The Spectroscopic Redshift Catalog

Science.gov (United States)

Yang, Ming; Wu, Hong; Yang, Fan; Lam, Man I.; Cao, Tian-Wen; Wu, Chao-Jian; Zhao, Pin-Song; Zhang, Tian-Meng; Zhou, Zhi-Min; Wu, Xue-Bing; Zhang, Yan-Xia; Shao, Zheng-Yi; Jing, Yi-Peng; Shen, Shi-Yin; Zhu, Yi-Nan; Du, Wei; Lei, Feng-Jie; He, Min; Jin, Jun-Jie; Shi, Jian-Rong; Zhang, Wei; Wang, Jian-Ling; Wu, Yu-Zhong; Zhang, Hao-Tong; Luo, A.-Li; Yuan, Hai-Long; Bai, Zhong-Rui; Kong, Xu; Gu, Qiu-Sheng; Zhou, Xu; Ma, Jun; Hu, Zou; Nie, Jun-Dan; Wang, Jia-Li; Zhang, Yong; Hou, Yong-Hui; Zhao, Yong-Heng

2018-01-01

We present a spectroscopic redshift catalog from the LAMOST Complete Spectroscopic Survey of Pointing Area (LaCoSSPAr) in the Southern Galactic Cap (SGC), which is designed to observe all sources (Galactic and extragalactic) by using repeating observations with a limiting magnitude of r=18.1 {mag} in two 20 {\\deg }2 fields. The project is mainly focusing on the completeness of LAMOST ExtraGAlactic Surveys (LEGAS) in the SGC, the deficiencies of source selection methods, and the basic performance parameters of the LAMOST telescope. In both fields, more than 95% of galaxies have been observed. A post-processing has been applied to the LAMOST 1D spectrum to remove the majority of remaining sky background residuals. More than 10,000 spectra have been visually inspected to measure the redshift by using combinations of different emission/absorption features with an uncertainty of {σ }z/(1+z)visual inspection. Our analysis also indicates that up to one-fourth of the input targets for a typical extragalactic spectroscopic survey might be unreliable. The multi-wavelength data analysis shows that the majority of mid-infrared-detected absorption (91.3%) and emission line galaxies (93.3%) can be well separated by an empirical criterion of W2-W3=2.4. Meanwhile, a fainter sequence paralleled to the main population of galaxies has been witnessed both in M r /W2-W3 and M */W2-W3 diagrams, which could be the population of luminous dwarf galaxies but contaminated by the edge-on/highly inclined galaxies (∼ 30 % ).

Domino effect in chemical accidents: main features and accident sequences.

Science.gov (United States)

Darbra, R M; Palacios, Adriana; Casal, Joaquim

2010-11-15

The main features of domino accidents in process/storage plants and in the transportation of hazardous materials were studied through an analysis of 225 accidents involving this effect. Data on these accidents, which occurred after 1961, were taken from several sources. Aspects analyzed included the accident scenario, the type of accident, the materials involved, the causes and consequences and the most common accident sequences. The analysis showed that the most frequent causes are external events (31%) and mechanical failure (29%). Storage areas (35%) and process plants (28%) are by far the most common settings for domino accidents. Eighty-nine per cent of the accidents involved flammable materials, the most frequent of which was LPG. The domino effect sequences were analyzed using relative probability event trees. The most frequent sequences were explosion→fire (27.6%), fire→explosion (27.5%) and fire→fire (17.8%). Copyright © 2010 Elsevier B.V. All rights reserved.

Discovery and characterization of 3000+ main-sequence binaries from APOGEE spectra

Science.gov (United States)

El-Badry, Kareem; Ting, Yuan-Sen; Rix, Hans-Walter; Quataert, Eliot; Weisz, Daniel R.; Cargile, Phillip; Conroy, Charlie; Hogg, David W.; Bergemann, Maria; Liu, Chao

2018-05-01

We develop a data-driven spectral model for identifying and characterizing spatially unresolved multiple-star systems and apply it to APOGEE DR13 spectra of main-sequence stars. Binaries and triples are identified as targets whose spectra can be significantly better fit by a superposition of two or three model spectra, drawn from the same isochrone, than any single-star model. From an initial sample of ˜20 000 main-sequence targets, we identify ˜2500 binaries in which both the primary and secondary stars contribute detectably to the spectrum, simultaneously fitting for the velocities and stellar parameters of both components. We additionally identify and fit ˜200 triple systems, as well as ˜700 velocity-variable systems in which the secondary does not contribute detectably to the spectrum. Our model simplifies the process of simultaneously fitting single- or multi-epoch spectra with composite models and does not depend on a velocity offset between the two components of a binary, making it sensitive to traditionally undetectable systems with periods of hundreds or thousands of years. In agreement with conventional expectations, almost all the spectrally identified binaries with measured parallaxes fall above the main sequence in the colour-magnitude diagram. We find excellent agreement between spectrally and dynamically inferred mass ratios for the ˜600 binaries in which a dynamical mass ratio can be measured from multi-epoch radial velocities. We obtain full orbital solutions for 64 systems, including 14 close binaries within hierarchical triples. We make available catalogues of stellar parameters, abundances, mass ratios, and orbital parameters.

CLIC main beam quadrupole active pre-alignment based on cam movers

CERN Document Server

Kemppinen, J; Leuxe, R; Mainaud Durand, H; Sandomierski, J; Sosin, M

2012-01-01

Compact Linear Collider (CLIC) is a study for a future 48 km long linear electron-positron collider in the multi TeV range. Its target luminosity can only be reached if the main beam quadrupoles (MB quads) are actively pre-aligned within 17 µm in sliding windows of 200 m with respect to a straight reference line. In addition to the positioning requirement, the pre-alignment system has to provide a rigid support for the nano-stabilization system to ensure that the first eigenfrequency is above 100 Hz. Re-adjustment based on cam movers was chosen for detailed studies to meet the stringent pre-alignment requirements. There are four different types of MB quads in CLIC. Their lengths and masses vary so that at least two types of cam movers have to be developed. The validation of the cams with less stringent space restrictions has proceeded to a test setup in 5 degrees of freedom (DOF). Prototypes of the more demanding, smaller cams have been manufactured and they are under tests in 1 DOF. This paper describes the...

SDSS-IV MaNGA: Spatially Resolved Star Formation Main Sequence and LI(N)ER Sequence

Science.gov (United States)

Hsieh, B. C.; Lin, Lihwai; Lin, J. H.; Pan, H. A.; Hsu, C. H.; Sánchez, S. F.; Cano-Díaz, M.; Zhang, K.; Yan, R.; Barrera-Ballesteros, J. K.; Boquien, M.; Riffel, R.; Brownstein, J.; Cruz-González, I.; Hagen, A.; Ibarra, H.; Pan, K.; Bizyaev, D.; Oravetz, D.; Simmons, A.

2017-12-01

We present our study on the spatially resolved Hα and M * relation for 536 star-forming and 424 quiescent galaxies taken from the MaNGA survey. We show that the star formation rate surface density ({{{Σ }}}{SFR}), derived based on the Hα emissions, is strongly correlated with the M * surface density ({{{Σ }}}* ) on kiloparsec scales for star-forming galaxies and can be directly connected to the global star-forming sequence. This suggests that the global main sequence may be a consequence of a more fundamental relation on small scales. On the other hand, our result suggests that ∼20% of quiescent galaxies in our sample still have star formation activities in the outer region with lower specific star formation rate (SSFR) than typical star-forming galaxies. Meanwhile, we also find a tight correlation between {{{Σ }}}{{H}α } and {{{Σ }}}* for LI(N)ER regions, named the resolved “LI(N)ER” sequence, in quiescent galaxies, which is consistent with the scenario that LI(N)ER emissions are primarily powered by the hot, evolved stars as suggested in the literature.

Impacts of WIMP dark matter upon stellar evolution: main-sequence stars

CERN Document Server

Scott, Pat; Edsjo, Joakim

2008-01-01

The presence of large amounts of WIMP dark matter in stellar cores has been shown to have significant effects upon models of stellar evolution. We present a series of detailed grids of WIMP-influenced stellar models for main sequence stars, computed using the DarkStars code. We describe the changes in stellar structure and main sequence evolution which occur for masses ranging from 0.3 to 2.0 solar masses and metallicities from Z = 0.0003-0.02, as a function of the rate of energy injection by WIMPs. We then go on to show what rates of energy injection can be obtained using realistic orbital parameters for stars near supermassive black holes, including detailed considerations of dark matter halo velocity and density profiles. Capture and annihilation rates are strongly boosted when stars follow elliptical rather than circular orbits, causing WIMP annihilation to provide up to 100 times the energy of hydrogen fusion in stars at the Galactic centre.

BVI CCD photometry of the broad main-sequence globular cluster NGC 1851

International Nuclear Information System (INIS)

Alcaino, G.; Liller, W.; Alvarado, F.; Wenderoth, E.

1990-01-01

Three-color CCD C-M diagrams are presented for the globular cluster NGC 1851, showing an extreme breadth of the main-sequence, similar to that of Omega Centauri. It is found that the main-sequence turnoff points are located at V(TO) = 19.44 + or - 0.10, with colors at B-V = 0.54 + or - 0.02, V-I = 0.61 + or - 0.02, and B-I = 1.15 + or - 0.03. The best fit to the VandenBerg and Bell (1985) isochrones is shown to be all C-M diagrams with Y = 0.20, Fe/H abundance ratio = -1.27, and (m-M)v = 15.45. It is concluded that NGC 1851 has a Delta V(TO - HB) = 3.34 + or - 0.10 and an age of 16 + or - 2 Gyr. 29 refs

Wolf-Rayet stars in the Magellanic Clouds: Spectroscopic binaries and masses

International Nuclear Information System (INIS)

Moffat, A.F.J.

1982-01-01

Repeated spectra to V-mag 13.0 (13.5) have been obtained since 1978 for the 25 (5) brightest WR stars in the LMC (SMC). More than half of these are orbiting spectroscopic binaries, mainly SB1 for the luminous subclasses WN6-9, and SB2 for the rest. Together with galactic data, the Cloud SB2's lead to a correlation between mass ratio WR/OB and WR spectral subclass for each of the WN and WC sequences. This correlation is interpreted as an evolutionary sequence in which the peeling-off process of the strong stellar wind exposes successively hotter regions and eventually converts WN to WC at a point in time which appears to depend on the ambient metal abundance. (Auth.)

A catalog of pre-main-sequence emission-line stars with IRAS source associations

International Nuclear Information System (INIS)

Weintraub, D.A.

1990-01-01

To aid in finding premain-sequence (PMS) emission-line stars that might have dusty circumstellar environments, 361 PMS stars that are associated with 304 separate IRAS sources were identified. These stars include 200 classical T Tauri stars, 25 weak-lined (naked) T Tauri stars, 56 Herbig Ae/Be stars, six FU Orionis stars, and two SU Aurigae stars. All six of the FU Orionis stars surveyed by IRAS were detected. Of the PMS-IRAS Point Source Catalog (PSC) associations, 90 are new and are not noted in the PSC. The other 271 entries include 104 that are correctly identified in the PSC but have not yet appeared in the literature, 56 more that can be found in both the PSC and in the published and unpublished iterature, and 111 that are in the literature but not in the PSC. Spectral slope diagrams constructed from the 12-, 25-, and 60-micron flux densities reveal unique distributions for the different PMS subclasses; these diagrams may help identify the best candidate PMS stars for observations of circumstellar dust. 30 refs

On the mass-spectrum relation for the main sequence stars

International Nuclear Information System (INIS)

Svechnikov, M.A.; Tajdakova, T.A.

1984-01-01

From 240 main-sequence stars with well-determined masses, a new mass-spectrum relation is obtained, which differs appreciably in certain intervals of spectral types from the mass-spectrum relations of Allen and Trimble. The accuracy of mass determination for the components of eclipsing binary systems of different types from their spectra given in the General Catalogue of Variable Stars (3rd edition) and in its supplements is evaluated

Main-sequence turnoff of the Draco dwarf galaxy

International Nuclear Information System (INIS)

Stetson, P.B.; Mcclure, R.D.; Vandenberg, D.A.; Victoria Univ., Canada)

1985-01-01

Deep photometry on the B,V system for 182 stars in the dwarf spheroidal galaxy in Draco was obtained with a CCD camera at the Cassegrain focus of the Canada-France-Hawaii 3.6-m telescope. Draco's main-sequence turnoff if found near V(to) = 23.5, which is about 3.4 magnitudes below the galaxy's horizontal branch. This leads to the interpretation that Draco is not measurably younger than the clusters or Ursa Minor: the age of Draco is about 18 Gyr according to current star-revolution chronologies. No blue stragglers are definitely detected in Draco, and it is concluded that any young population in Draco probably represents less than 10 percent of the total. 30 references

Possible evidence for metal accretion onto the surfaces of metal-poor main-sequence stars

Energy Technology Data Exchange (ETDEWEB)

Hattori, Kohei; Yoshii, Yuzuru [Institute of Astronomy, School of Science, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Beers, Timothy C. [National Optical Astronomy Observatories, Tucson, AZ 85719 (United States); Carollo, Daniela [Department of Physics and Astronomy, Macquarie University, Sydney, 2109 NSW (Australia); Lee, Young Sun, E-mail: khattori@ioa.s.u-tokyo.ac.jp [Department of Astronomy, New Mexico State University, Las Cruces, NM 88003 (United States)

2014-04-01

The entire evolution of the Milky Way, including its mass-assembly and star-formation history, is imprinted onto the chemo-dynamical distribution function of its member stars, f(x, v, [X/H]), in the multi-dimensional phase space spanned by position, velocity, and elemental abundance ratios. In particular, the chemo-dynamical distribution functions for low-mass stars (e.g., G- or K-type dwarfs) are precious tracers of the earliest stages of the Milky Way's formation, since their main-sequence lifetimes approach or exceed the age of the universe. A basic tenet of essentially all previous analyses is that the stellar metallicity, usually parameterized as [Fe/H], is conserved over time for main-sequence stars (at least those that have not been polluted due to mass transfer from binary companions). If this holds true, any correlations between metallicity and kinematics for long-lived main-sequence stars of different masses, effective temperatures, or spectral types must strictly be the same, since they reflect the same mass-assembly and star-formation histories. By analyzing a sample of nearby metal-poor halo and thick-disk stars on the main sequence, taken from Data Release 8 of the Sloan Digital Sky Survey, we find that the median metallicity of G-type dwarfs is systematically higher (by about 0.2 dex) than that of K-type dwarfs having the same median rotational velocity about the Galactic center. If it can be confirmed, this finding may invalidate the long-accepted assumption that the atmospheric metallicities of long-lived stars are conserved over time.

Domino effect in chemical accidents: main features and accident sequences

OpenAIRE

Casal Fàbrega, Joaquim; Darbra Roman, Rosa Maria

2010-01-01

The main features of domino accidents in process/storage plants and in the transportation of hazardous materials were studied through an analysis of 225 accidents involving this effect. Data on these accidents, which occurred after 1961, were taken from several sources. Aspects analyzed included the accident scenario, the type of accident, the materials involved, the causes and consequences and the most common accident sequences. The analysis showed that the most frequent causes a...

The V Band Empirical Mass-Luminosity Relation for Main Sequence Stars

Science.gov (United States)

Xia, F.; Fu, Y. N.

2010-01-01

Stellar mass is an indispensable parameter in the studies of stellar physics and stellar dynamics. On the one hand, the most reliable way to determine the stellar dynamical mass is via orbital determination of binaries. On the other hand, however, most stellar masses have to be estimated by using the mass-luminosity relation (MLR). Therefore, it is important to obtain the empirical MLR through fitting the data of stellar dynamical mass and luminosity. The effect of metallicity can make this relation disperse in the V-band, but studies show that this is mainly limited to the case when the stellar mass is less than 0.6M⊙. Recently, many relevant data have been accumulated for main sequence stars with larger mass, which make it possible to significantly improve the corresponding MLR. Using a fitting method which can reasonably assign weight to the observational data including two quantities with different dimensions, we obtain a V-band MLR based on the dynamical masses and luminosities of 203 main sequence stars. Compared with the previous work, the improved MLR is statistically significant, and the relative error of mass estimation reaches about 5%. Therefore, our MLR is useful not only in studies of statistical nature, but also in studies of concrete stellar systems, such as the long-term dynamical study and the short-term positioning study of a specific multiple star system.

The V-band Empirical Mass-luminosity Relation for Main Sequence Stars

Science.gov (United States)

Xia, Fang; Fu, Yan-Ning

2010-07-01

Stellar mass is an indispensable parameter in the studies of stellar physics and stellar dynamics. On the one hand, the most reliable way to determine the stellar dynamical mass is via orbital determinations of binaries. On the other hand, however, most stellar masses have to be estimated by using the mass luminosity relation (MLR). Therefore, it is important to obtain the empirical MLR through fitting the data of stellar dynamical mass and luminosity. The effect of metallicity can make this relation disperse in the V-band, but studies show that this is mainly limited to the case when the stellar mass is less than 0.6M⊙ Recently, many relevant data have been accumulated for main sequence stars with larger masses, which make it possible to significantly improve the corresponding MLR. Using a fitting method which can reasonably assign weights to the observational data including two quantities with different dimensions, we obtain a V-band MLR based on the dynamical masses and luminosities of 203 main sequence stars. In comparison with the previous work, the improved MLR is statistically significant, and the relative error of mass estimation reaches about 5%. Therefore, our MLR is useful not only in the studies of statistical nature, but also in the studies of concrete stellar systems, such as the long-term dynamical study and the short-term positioning study of a specific multiple star system.

EFFECT OF METALLICITY ON THE EVOLUTION OF THE HABITABLE ZONE FROM THE PRE-MAIN SEQUENCE TO THE ASYMPTOTIC GIANT BRANCH AND THE SEARCH FOR LIFE

Energy Technology Data Exchange (ETDEWEB)

Danchi, William C. [Exoplanets and Stellar Astrophysics Laboratory, NASA Goddard Space Flight Center, Code 667, Greenbelt, MD 20771 (United States); Lopez, Bruno, E-mail: william.c.danchi@nasa.gov, E-mail: bruno.lopez@oca.eu [Observatoire de la Cote d' Azur, Laboratoire Lagrange UMR 7293, BP 4229, F-06034 Nice Cedex 4 (France)

2013-05-20

During the course of stellar evolution, the location and width of the habitable zone changes as the luminosity and radius of the star evolves. The duration of habitability for a planet located at a given distance from a star is greatly affected by the characteristics of the host star. A quantification of these effects can be used observationally in the search for life around nearby stars. The longer the duration of habitability, the more likely it is that life has evolved. The preparation of observational techniques aimed at detecting life would benefit from the scientific requirements deduced from the evolution of the habitable zone. We present a study of the evolution of the habitable zone around stars of 1.0, 1.5, and 2.0 M{sub Sun} for metallicities ranging from Z = 0.0001 to Z = 0.070. We also consider the evolution of the habitable zone from the pre-main sequence until the asymptotic giant branch is reached. We find that metallicity strongly affects the duration of the habitable zone for a planet as well as the distance from the host star where the duration is maximized. For a 1.0 M{sub Sun} star with near solar metallicity, Z = 0.017, the duration of the habitable zone is >10 Gyr at distances 1.2-2.0 AU from the star, whereas the duration is >20 Gyr for high-metallicity stars (Z = 0.070) at distances of 0.7-1.8 AU, and {approx}4 Gyr at distances of 1.8-3.3 AU for low-metallicity stars (Z = 0.0001). Corresponding results have been obtained for stars of 1.5 and 2.0 solar masses.

EFFECT OF METALLICITY ON THE EVOLUTION OF THE HABITABLE ZONE FROM THE PRE-MAIN SEQUENCE TO THE ASYMPTOTIC GIANT BRANCH AND THE SEARCH FOR LIFE

International Nuclear Information System (INIS)

Danchi, William C.; Lopez, Bruno

2013-01-01

During the course of stellar evolution, the location and width of the habitable zone changes as the luminosity and radius of the star evolves. The duration of habitability for a planet located at a given distance from a star is greatly affected by the characteristics of the host star. A quantification of these effects can be used observationally in the search for life around nearby stars. The longer the duration of habitability, the more likely it is that life has evolved. The preparation of observational techniques aimed at detecting life would benefit from the scientific requirements deduced from the evolution of the habitable zone. We present a study of the evolution of the habitable zone around stars of 1.0, 1.5, and 2.0 M ☉ for metallicities ranging from Z = 0.0001 to Z = 0.070. We also consider the evolution of the habitable zone from the pre-main sequence until the asymptotic giant branch is reached. We find that metallicity strongly affects the duration of the habitable zone for a planet as well as the distance from the host star where the duration is maximized. For a 1.0 M ☉ star with near solar metallicity, Z = 0.017, the duration of the habitable zone is >10 Gyr at distances 1.2-2.0 AU from the star, whereas the duration is >20 Gyr for high-metallicity stars (Z = 0.070) at distances of 0.7-1.8 AU, and ∼4 Gyr at distances of 1.8-3.3 AU for low-metallicity stars (Z = 0.0001). Corresponding results have been obtained for stars of 1.5 and 2.0 solar masses.

Magnetic fields in O-, B- and A-type stars on the main sequence

Directory of Open Access Journals (Sweden)

Briquet Maryline

2015-01-01

Full Text Available In this review, the latest observational results on magnetic fields in main-sequence stars with radiative envelopes are summarised together with the theoretical works aimed at explaining them.

Variability of Disk Emission in Pre-Main Sequence and Related Stars. II. Variability in the Gas and Dust Emission of the Herbig Fe Star SAO 206462

Science.gov (United States)

Sitko, Michael L.; Day, Amanda N.; Kimes, Robin L.; Beerman, Lori C.; Martus, Cameron; Lynch, David K.; Russell, Ray W.; Grady, Carol A.; Schneider, Glenn; Lisse, Carey M.;

A consistency test of white dwarf and main sequence ages: NGC 6791

Directory of Open Access Journals (Sweden)

Córsico A.H.

2013-03-01

Full Text Available NGC 6791 is an open cluster that it is so close to us that can be imaged down to very faint luminosities. The main sequence turn-off age (∼8 Gyr and the age derived from the cut-off of the white dwarf luminosity function (∼6 Gyr were found to be significantly different. Here we demonstrate that the origin of this age discrepancy lies in an incorrect evaluation of the white dwarf cooling ages, and we show that when the relevant physical separation processes are included in the calculation of white dwarf sequences both ages are coincident.

Infrared photometry of upper main sequence stars in M39

International Nuclear Information System (INIS)

Manteiga, M.; Martinez-Roger, C.; Morales, C.; Sabau, L.

1991-01-01

Infrared photometry of 19 Main sequence stars in the open cluster M39 is presented. Infrared-infrared and optical-infrared colour-colour and colour-magnitude diagrams are presented and compared with mean intrinsic colours for Population I stars. An interstellar reddening of E(B - V) = 0.01 is obtained by analysis of the colour-colour diagrams. Comparison with a set of theoretical isochrones leads to an age estimate for the cluster between 2.4 and 4.8 x 10 8 years

Infrared photometry of upper main sequence stars in M39

Energy Technology Data Exchange (ETDEWEB)

Manteiga, M.; Martinez-Roger, C. (Instituto de Astrofisica de Canarias, Tenerife, (ES)); Morales, C.; Sabau, L. (Instituto de Tecnica Aeroespacial, Madrid, (ES))

1991-03-01

Infrared photometry of 19 Main sequence stars in the open cluster M39 is presented. Infrared-infrared and optical-infrared colour-colour and colour-magnitude diagrams are presented and compared with mean intrinsic colours for Population I stars. An interstellar reddening of E(B - V) = 0.01 is obtained by analysis of the colour-colour diagrams. Comparison with a set of theoretical isochrones leads to an age estimate for the cluster between 2.4 and 4.8 x 10{sup 8} years.

The main sequence of NGC 6231 and the calibration of absolute magnitudes

International Nuclear Information System (INIS)

Garrison, R.F.

1978-01-01

The author presents a discussion of a new approach to the calibration of absolute magnitudes for MK spectral types. With the addition of the NGC 6231 main sequence down to A0, the material for the cluster fitting method using very carefully determined MK types is complete. (Auth.)

RADIO AND MID-INFRARED PROPERTIES OF COMPACT STARBURSTS: DISTANCING THEMSELVES FROM THE MAIN SEQUENCE

Energy Technology Data Exchange (ETDEWEB)

Murphy, E. J. [Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Stierwalt, S.; Armus, L. [Spitzer Science Center, California Institute of Technology, MC 314-6, Pasadena, CA 91125 (United States); Condon, J. J. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Evans, A. S., E-mail: emurphy@obs.carnegiescience.edu [Department of Astronomy, University of Virginia, 530 McCormick Road, Charlottesville, VA 22904 (United States)

2013-05-01

We investigate the relationship between 8.44 GHz brightness temperatures and 1.4 to 8.44 GHz radio spectral indices with 6.2 {mu}m polycyclic aromatic hydrocarbon (PAH) emission and 9.7 {mu}m silicate absorption features for a sample of 36 local luminous and ultraluminous infrared galaxies. We find that galaxies having small 6.2 {mu}m PAH equivalent widths (EQWs), which signal the presence of weak PAH emission and/or an excess of very hot dust, also have flat spectral indices. The three active galactic nuclei (AGN) identified through their excessively large 8.44 GHz brightness temperatures are also identified as AGN via their small 6.2 {mu}m PAH EQWs. We also find that the flattening of the radio spectrum increases with increasing silicate optical depth, 8.44 GHz brightness temperature, and decreasing size of the radio source even after removing potential AGN, supporting the idea that compact starbursts show spectral flattening as the result of increased free-free absorption. These correlations additionally suggest that the dust obscuration in these galaxies must largely be coming from the vicinity of the compact starburst itself, and is not distributed throughout the (foreground) disk of the galaxy. Finally, we investigate the location of these infrared-bright systems relative to the main sequence (star formation rate versus stellar mass) of star-forming galaxies in the local universe. We find that the radio spectral indices of galaxies flatten with increasing distance above the main sequence, or in other words, with increasing specific star formation rate. This indicates that galaxies located above the main sequence, having high specific star formation rates, are typically compact starbursts hosting deeply embedded star formation that becomes more optically thick in the radio and infrared with increased distance above the main sequence.

Analysis of Pre-Analytic Factors Affecting the Success of Clinical Next-Generation Sequencing of Solid Organ Malignancies

International Nuclear Information System (INIS)

Chen, Hui; Luthra, Rajyalakshmi; Goswami, Rashmi S.; Singh, Rajesh R.; Roy-Chowdhuri, Sinchita

2015-01-01

Application of next-generation sequencing (NGS) technology to routine clinical practice has enabled characterization of personalized cancer genomes to identify patients likely to have a response to targeted therapy. The proper selection of tumor sample for downstream NGS based mutational analysis is critical to generate accurate results and to guide therapeutic intervention. However, multiple pre-analytic factors come into play in determining the success of NGS testing. In this review, we discuss pre-analytic requirements for AmpliSeq PCR-based sequencing using Ion Torrent Personal Genome Machine (PGM) (Life Technologies), a NGS sequencing platform that is often used by clinical laboratories for sequencing solid tumors because of its low input DNA requirement from formalin fixed and paraffin embedded tissue. The success of NGS mutational analysis is affected not only by the input DNA quantity but also by several other factors, including the specimen type, the DNA quality, and the tumor cellularity. Here, we review tissue requirements for solid tumor NGS based mutational analysis, including procedure types, tissue types, tumor volume and fraction, decalcification, and treatment effects

Analysis of Pre-Analytic Factors Affecting the Success of Clinical Next-Generation Sequencing of Solid Organ Malignancies

Energy Technology Data Exchange (ETDEWEB)

Chen, Hui [Department of Pathology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030 (United States); Luthra, Rajyalakshmi, E-mail: rluthra@mdanderson.org; Goswami, Rashmi S.; Singh, Rajesh R. [Department of Hematopathology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030 (United States); Roy-Chowdhuri, Sinchita [Department of Pathology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030 (United States)

2015-08-28

Application of next-generation sequencing (NGS) technology to routine clinical practice has enabled characterization of personalized cancer genomes to identify patients likely to have a response to targeted therapy. The proper selection of tumor sample for downstream NGS based mutational analysis is critical to generate accurate results and to guide therapeutic intervention. However, multiple pre-analytic factors come into play in determining the success of NGS testing. In this review, we discuss pre-analytic requirements for AmpliSeq PCR-based sequencing using Ion Torrent Personal Genome Machine (PGM) (Life Technologies), a NGS sequencing platform that is often used by clinical laboratories for sequencing solid tumors because of its low input DNA requirement from formalin fixed and paraffin embedded tissue. The success of NGS mutational analysis is affected not only by the input DNA quantity but also by several other factors, including the specimen type, the DNA quality, and the tumor cellularity. Here, we review tissue requirements for solid tumor NGS based mutational analysis, including procedure types, tissue types, tumor volume and fraction, decalcification, and treatment effects.

Analysis of Pre-Analytic Factors Affecting the Success of Clinical Next-Generation Sequencing of Solid Organ Malignancies

Directory of Open Access Journals (Sweden)

Hui Chen

2015-08-01

Full Text Available Application of next-generation sequencing (NGS technology to routine clinical practice has enabled characterization of personalized cancer genomes to identify patients likely to have a response to targeted therapy. The proper selection of tumor sample for downstream NGS based mutational analysis is critical to generate accurate results and to guide therapeutic intervention. However, multiple pre-analytic factors come into play in determining the success of NGS testing. In this review, we discuss pre-analytic requirements for AmpliSeq PCR-based sequencing using Ion Torrent Personal Genome Machine (PGM (Life Technologies, a NGS sequencing platform that is often used by clinical laboratories for sequencing solid tumors because of its low input DNA requirement from formalin fixed and paraffin embedded tissue. The success of NGS mutational analysis is affected not only by the input DNA quantity but also by several other factors, including the specimen type, the DNA quality, and the tumor cellularity. Here, we review tissue requirements for solid tumor NGS based mutational analysis, including procedure types, tissue types, tumor volume and fraction, decalcification, and treatment effects.

HABITABLE ZONES OF POST-MAIN SEQUENCE STARS

International Nuclear Information System (INIS)

Ramirez, Ramses M.; Kaltenegger, Lisa

2016-01-01

Once a star leaves the main sequence and becomes a red giant, its Habitable Zone (HZ) moves outward, promoting detectable habitable conditions at larger orbital distances. We use a one-dimensional radiative-convective climate and stellar evolutionary models to calculate post-MS HZ distances for a grid of stars from 3700 to 10,000 K (∼M1 to A5 stellar types) for different stellar metallicities. The post-MS HZ limits are comparable to the distances of known directly imaged planets. We model the stellar as well as planetary atmospheric mass loss during the Red Giant Branch (RGB) and Asymptotic Giant Branch (AGB) phases for super-Moons to super-Earths. A planet can stay between 200 million years up to 9 Gyr in the post-MS HZ for our hottest and coldest grid stars, respectively, assuming solar metallicity. These numbers increase for increased stellar metallicity. Total atmospheric erosion only occurs for planets in close-in orbits. The post-MS HZ orbital distances are within detection capabilities of direct imaging techniques.

HABITABLE ZONES OF POST-MAIN SEQUENCE STARS

Energy Technology Data Exchange (ETDEWEB)

Ramirez, Ramses M.; Kaltenegger, Lisa [Carl Sagan Institute, Cornell University, Ithaca, NY (United States)

2016-05-20

Once a star leaves the main sequence and becomes a red giant, its Habitable Zone (HZ) moves outward, promoting detectable habitable conditions at larger orbital distances. We use a one-dimensional radiative-convective climate and stellar evolutionary models to calculate post-MS HZ distances for a grid of stars from 3700 to 10,000 K (∼M1 to A5 stellar types) for different stellar metallicities. The post-MS HZ limits are comparable to the distances of known directly imaged planets. We model the stellar as well as planetary atmospheric mass loss during the Red Giant Branch (RGB) and Asymptotic Giant Branch (AGB) phases for super-Moons to super-Earths. A planet can stay between 200 million years up to 9 Gyr in the post-MS HZ for our hottest and coldest grid stars, respectively, assuming solar metallicity. These numbers increase for increased stellar metallicity. Total atmospheric erosion only occurs for planets in close-in orbits. The post-MS HZ orbital distances are within detection capabilities of direct imaging techniques.

Oscillation mode linewidths of main-sequence and subgiant stars observed by Kepler

DEFF Research Database (Denmark)

Appourchaux, T.; Benomar, O.; Gruberbauer, M.

2012-01-01

Solar-like oscillations have been observed by {{\\it Kepler}} and CoRoT in several solar-type stars. We study the variations of stellar p-mode linewidth as a function of effective temperature. Time series of 9 months of Kepler data have been used. The power spectra of 42 cool main-sequence stars a...

A trans-activator function is generated by integration of hepatitis B virus preS/S sequences in human hepatocellular carcinoma DNA

International Nuclear Information System (INIS)

Caselmann, W.H.; Meyer, M.; Kekule, A.S.; Lauer, U.; Hofschneider, P.H.; Koshy, R.

1990-01-01

The X gene of wild-type hepatitis B virus or integrated DNA has recently been shown to stimulate transcription of a variety of enhancers and promoters. To further delineate the viral sequences responsible for trans-activation in hepatomas, the authors cloned the single hepatitis B virus insert from human hepatocellular carcinoma DNA M1. The plasmid pM1 contains 2004 base of hepatitis B virus DNA subtype adr, including truncated preS/S sequences and the enhancer element. The X promoter and 422 nucleotides of the X coding region are present. The entire preC/C gene is deleted. In transient cotransfection assays using Chang liver cells (CCL 13), pM1 DNA exerts a 6- to 10-fold trans-activating effect on the expression of the pSV2CAT reporter plasmid. The transactivation occurs by stimulation of transcription and is dependent on the simian virus 40 enhancer in the reporter plasmid. Deletion analysis of pM1 subclones reveals that the transactivator is encoded by preS/S and not by X sequences. A frameshift mutation within the preS2 open reading frame shows that this portion is indispensable for the trans-activating function. Initiation of transcription has been mapped to the S1 promoter. A comparable trans-activating effect is also observed with cloned wild-type hepatitis B virus sequences similarly truncated. These results show that a transcriptional trans-activator function not present in the intact gene is generated by 3' truncation of integrated hepatitis B virus DNA preS/S sequences

Asteroseismic measurement of surface-to-core rotation in a main-sequence star*

Directory of Open Access Journals (Sweden)

Kurtz Donald W.

2015-01-01

Full Text Available We have discovered rotationally split core g-mode triplets and surface p-mode triplets and quintuplets in a terminal age main-sequence A star, KIC 11145123, that shows both δ Sct p-mode pulsations and γ Dor g-mode pulsations. This gives the first robust determination of the rotation of the deep core and surface of a main-sequence star, essentially model-independently. We find its rotation to be nearly uniform with a period near 100 d, but we show with high confidence that the surface rotates slightly faster than the core. A strong angular momentum transfer mechanism must be operating to produce the nearly rigid rotation, and a mechanism other than viscosity must be operating to produce a more rapidly rotating surface than core. Our asteroseismic result, along with previous asteroseismic constraints on internal rotation in some B stars, and measurements of internal rotation in some subgiant, giant and white dwarf stars, has made angular momentum transport in stars throughout their lifetimes an observational science.

A subspace approach to high-resolution spectroscopic imaging.

Science.gov (United States)

Lam, Fan; Liang, Zhi-Pei

2014-04-01

To accelerate spectroscopic imaging using sparse sampling of (k,t)-space and subspace (or low-rank) modeling to enable high-resolution metabolic imaging with good signal-to-noise ratio. The proposed method, called SPectroscopic Imaging by exploiting spatiospectral CorrElation, exploits a unique property known as partial separability of spectroscopic signals. This property indicates that high-dimensional spectroscopic signals reside in a very low-dimensional subspace and enables special data acquisition and image reconstruction strategies to be used to obtain high-resolution spatiospectral distributions with good signal-to-noise ratio. More specifically, a hybrid chemical shift imaging/echo-planar spectroscopic imaging pulse sequence is proposed for sparse sampling of (k,t)-space, and a low-rank model-based algorithm is proposed for subspace estimation and image reconstruction from sparse data with the capability to incorporate prior information and field inhomogeneity correction. The performance of the proposed method has been evaluated using both computer simulations and phantom studies, which produced very encouraging results. For two-dimensional spectroscopic imaging experiments on a metabolite phantom, a factor of 10 acceleration was achieved with a minimal loss in signal-to-noise ratio compared to the long chemical shift imaging experiments and with a significant gain in signal-to-noise ratio compared to the accelerated echo-planar spectroscopic imaging experiments. The proposed method, SPectroscopic Imaging by exploiting spatiospectral CorrElation, is able to significantly accelerate spectroscopic imaging experiments, making high-resolution metabolic imaging possible. Copyright © 2014 Wiley Periodicals, Inc.

The evolution of surface magnetic fields in young solar-type stars II: the early main sequence (250-650 Myr)

Science.gov (United States)

Folsom, C. P.; Bouvier, J.; Petit, P.; Lèbre, A.; Amard, L.; Palacios, A.; Morin, J.; Donati, J.-F.; Vidotto, A. A.

2018-03-01

There is a large change in surface rotation rates of sun-like stars on the pre-main sequence and early main sequence. Since these stars have dynamo-driven magnetic fields, this implies a strong evolution of their magnetic properties over this time period. The spin-down of these stars is controlled by interactions between stellar and magnetic fields, thus magnetic evolution in turn plays an important role in rotational evolution. We present here the second part of a study investigating the evolution of large-scale surface magnetic fields in this critical time period. We observed stars in open clusters and stellar associations with known ages between 120 and 650 Myr, and used spectropolarimetry and Zeeman Doppler Imaging to characterize their large-scale magnetic field strength and geometry. We report 15 stars with magnetic detections here. These stars have masses from 0.8 to 0.95 M⊙, rotation periods from 0.326 to 10.6 d, and we find large-scale magnetic field strengths from 8.5 to 195 G with a wide range of geometries. We find a clear trend towards decreasing magnetic field strength with age, and a power law decrease in magnetic field strength with Rossby number. There is some tentative evidence for saturation of the large-scale magnetic field strength at Rossby numbers below 0.1, although the saturation point is not yet well defined. Comparing to younger classical T Tauri stars, we support the hypothesis that differences in internal structure produce large differences in observed magnetic fields, however for weak-lined T Tauri stars this is less clear.

De novo Transcriptome Sequencing Reveals a Considerable Bias in the Incidence of Simple Sequence Repeats towards the Downstream of ‘Pre-miRNAs’ of Black Pepper

Science.gov (United States)

Joy, Nisha; Asha, Srinivasan; Mallika, Vijayan; Soniya, Eppurathu Vasudevan

2013-01-01

Next generation sequencing has an advantageon transformational development of species with limited available sequence data as it helps to decode the genome and transcriptome. We carried out the de novo sequencing using illuminaHiSeq™ 2000 to generate the first leaf transcriptome of black pepper (Piper nigrum L.), an important spice variety native to South India and also grown in other tropical regions. Despite the economic and biochemical importance of pepper, a scientifically rigorous study at the molecular level is far from complete due to lack of sufficient sequence information and cytological complexity of its genome. The 55 million raw reads obtained, when assembled using Trinity program generated 2,23,386 contigs and 1,28,157 unigenes. Reports suggest that the repeat-rich genomic regions give rise to small non-coding functional RNAs. MicroRNAs (miRNAs) are the most abundant type of non-coding regulatory RNAs. In spite of the widespread research on miRNAs, little is known about the hair-pin precursors of miRNAs bearing Simple Sequence Repeats (SSRs). We used the array of transcripts generated, for the in silico prediction and detection of ‘43 pre-miRNA candidates bearing different types of SSR motifs’. The analysis identified 3913 different types of SSR motifs with an average of one SSR per 3.04 MB of thetranscriptome. About 0.033% of the transcriptome constituted ‘pre-miRNA candidates bearing SSRs’. The abundance, type and distribution of SSR motifs studied across the hair-pin miRNA precursors, showed a significant bias in the position of SSRs towards the downstream of predicted ‘pre-miRNA candidates’. The catalogue of transcripts identified, together with the demonstration of reliable existence of SSRs in the miRNA precursors, permits future opportunities for understanding the genetic mechanism of black pepper and likely functions of ‘tandem repeats’ in miRNAs. PMID:23469176

Spectroscopic characterization of galaxy clusters in RCS-1: spectroscopic confirmation, redshift accuracy, and dynamical mass-richness relation

Science.gov (United States)

Gilbank, David G.; Barrientos, L. Felipe; Ellingson, Erica; Blindert, Kris; Yee, H. K. C.; Anguita, T.; Gladders, M. D.; Hall, P. B.; Hertling, G.; Infante, L.; Yan, R.; Carrasco, M.; Garcia-Vergara, Cristina; Dawson, K. S.; Lidman, C.; Morokuma, T.

2018-05-01

We present follow-up spectroscopic observations of galaxy clusters from the first Red-sequence Cluster Survey (RCS-1). This work focuses on two samples, a lower redshift sample of ˜30 clusters ranging in redshift from z ˜ 0.2-0.6 observed with multiobject spectroscopy (MOS) on 4-6.5-m class telescopes and a z ˜ 1 sample of ˜10 clusters 8-m class telescope observations. We examine the detection efficiency and redshift accuracy of the now widely used red-sequence technique for selecting clusters via overdensities of red-sequence galaxies. Using both these data and extended samples including previously published RCS-1 spectroscopy and spectroscopic redshifts from SDSS, we find that the red-sequence redshift using simple two-filter cluster photometric redshifts is accurate to σz ≈ 0.035(1 + z) in RCS-1. This accuracy can potentially be improved with better survey photometric calibration. For the lower redshift sample, ˜5 per cent of clusters show some (minor) contamination from secondary systems with the same red-sequence intruding into the measurement aperture of the original cluster. At z ˜ 1, the rate rises to ˜20 per cent. Approximately ten per cent of projections are expected to be serious, where the two components contribute significant numbers of their red-sequence galaxies to another cluster. Finally, we present a preliminary study of the mass-richness calibration using velocity dispersions to probe the dynamical masses of the clusters. We find a relation broadly consistent with that seen in the local universe from the WINGS sample at z ˜ 0.05.

Environmental impact analysis for the main accidental sequences of ignitor

International Nuclear Information System (INIS)

Carpignano, A.; Francabandiera, S.; Vella, R.; Zucchetti, M.

1996-01-01

A safety analysis study has been applied to the Ignitor machine using Probabilistic Safety Assessment. The main initiating events have been identified, and accident sequences have been studied by means of traditional methods such as Failure Mode and Effect Analysis (FMEA), Fault Trees (FT) and Event Trees (ET). The consequences of the radioactive environmental releases have been assessed in terms of Effective Dose Equivalent (EDEs) to the Most Exposed Individuals (MEI) of the chosen site, by means of a population dose code. Results point out the low enviromental impact of the machine. 13 refs., 1 fig., 3 tabs

XMM-NEWTON MONITORING OF THE CLOSE PRE-MAIN-SEQUENCE BINARY AK SCO. EVIDENCE OF TIDE-DRIVEN FILLING OF THE INNER GAP IN THE CIRCUMBINARY DISK

Energy Technology Data Exchange (ETDEWEB)

Gomez de Castro, Ana Ines [S. D. Astronomia y Geodesia and Instituto de Matematica Interdisciplinar, Fac. de CC Matematicas, Universidad Complutense, E-28040 Madrid (Spain); Lopez-Santiago, Javier [Departamento de Astrofisica, Fac de CC Fisicas, Universidad Complutense, E-28040 Madrid (Spain); Talavera, Antonio [European Space Astronomy Center, Villanueva de la Canada, E-28691, Madrid (Spain); Sytov, A. Yu.; Bisikalo, D. [Institute of Astronomy of the Russian Academy of Sciences, Pyatnitskaya St. 48, 109017 Moscow (Russian Federation)

2013-03-20

AK Sco stands out among pre-main-sequence binaries because of its prominent ultraviolet excess, the high eccentricity of its orbit, and the strong tides driven by it. AK Sco consists of two F5-type stars that get as close as 11 R{sub *} at periastron passage. The presence of a dense (n{sub e} {approx} 10{sup 11} cm{sup -3}) extended envelope has been unveiled recently. In this article, we report the results from an XMM-Newton-based monitoring of the system. We show that at periastron, X-ray and UV fluxes are enhanced by a factor of {approx}3 with respect to the apastron values. The X-ray radiation is produced in an optically thin plasma with T {approx} 6.4 Multiplication-Sign 10{sup 6} K and it is found that the N{sub H} column density rises from 0.35 Multiplication-Sign 10{sup 21} cm{sup -2} at periastron to 1.11 Multiplication-Sign 10{sup 21} cm{sup -2} at apastron, in good agreement with previous polarimetric observations. The UV emission detected in the Optical Monitor band seems to be caused by the reprocessing of the high-energy magnetospheric radiation on the circumstellar material. Further evidence of the strong magnetospheric disturbances is provided by the detection of line broadening of 278.7 km s{sup -1} in the N V line with Hubble Space Telescope/Space Telescope Imaging Spectrograph. Numerical simulations of the mass flow from the circumbinary disk to the components have been carried out. They provide a consistent scenario with which to interpret AK Sco observations. We show that the eccentric orbit acts like a gravitational piston. At apastron, matter is dragged efficiently from the inner disk border, filling the inner gap and producing accretion streams that end as ring-like structures around each component of the system. At periastron, the ring-like structures come into contact, leading to angular momentum loss, and thus producing an accretion outburst.

Effects of main-sequence mass loss on the turnoff ages of globular clusters

International Nuclear Information System (INIS)

Guzik, J.A.

1989-01-01

Willson, Bowen, and Struck-Marcell have proposed that globular cluster main-sequence turnoff ages can be reconciled with the lower ages of the Galaxy and universe deduced from other methods by incorporating an epoch of early main-sequence mass-loss by stars of spectral types A through early-F. The proposed mass loss is pulsation-driven, and facilitated by rapid rotation. This paper presents stellar evolution calculations of Pop. II (Z = 0.001) mass-losing stars of initial mass 0.8 to 1.6 M circle dot , with exponentially-decreasing mass loss rates of e-folding times 0.5 to 2.0 Gyr, evolving to a final mass of 0.7 M circle dot . The calculations indicate that a globular cluster with apparent turnoff age 18 Gyr could have an actual age as low as ∼12 Gyr. Observational implications that may help to verify the hypothesis, e.g. low C/N abundance ratios among red giants following first dredge-up, blue stragglers, red giant deficiencies, and signatures in cluster mass/luminosity functions, are also discussed.25 refs., 4 figs., 3 tabs

Quantitative analysis of polycomb response elements (PREs at identical genomic locations distinguishes contributions of PRE sequence and genomic environment

Directory of Open Access Journals (Sweden)

Okulski Helena

2011-03-01

Full Text Available Abstract Background Polycomb/Trithorax response elements (PREs are cis-regulatory elements essential for the regulation of several hundred developmentally important genes. However, the precise sequence requirements for PRE function are not fully understood, and it is also unclear whether these elements all function in a similar manner. Drosophila PRE reporter assays typically rely on random integration by P-element insertion, but PREs are extremely sensitive to genomic position. Results We adapted the ΦC31 site-specific integration tool to enable systematic quantitative comparison of PREs and sequence variants at identical genomic locations. In this adaptation, a miniwhite (mw reporter in combination with eye-pigment analysis gives a quantitative readout of PRE function. We compared the Hox PRE Frontabdominal-7 (Fab-7 with a PRE from the vestigial (vg gene at four landing sites. The analysis revealed that the Fab-7 and vg PREs have fundamentally different properties, both in terms of their interaction with the genomic environment at each site and their inherent silencing abilities. Furthermore, we used the ΦC31 tool to examine the effect of deletions and mutations in the vg PRE, identifying a 106 bp region containing a previously predicted motif (GTGT that is essential for silencing. Conclusions This analysis showed that different PREs have quantifiably different properties, and that changes in as few as four base pairs have profound effects on PRE function, thus illustrating the power and sensitivity of ΦC31 site-specific integration as a tool for the rapid and quantitative dissection of elements of PRE design.

SMALL MAIN-BELT ASTEROID SPECTROSCOPIC SURVEY, PHASE II

Data.gov (United States)

National Aeronautics and Space Administration — This data set contains visible-wavelength (0.435-0.925 micron) spectra for 1341 main-belt asteroids observed during the second phase of the Small Main-belt Asteroid...

A Spectroscopic and Electrochemical Investigation of Interactions of Anticancer Uracil Derivatives with Cationic and Anionic Surfactants

International Nuclear Information System (INIS)

Zafar, F.; Shah, A.; Ahmad, Z.; Siddiq, M.; Ali, S.; Asad Muhammad Khan, A. M.; Rana, U. A.

2015-01-01

Interactions of 5-fluorouracil (5-FU), a commercially available anti-cancer drug and two other possibly anti-cancer actives, 2-thiouracil (2-TU) and 2,4-dithiouracil (DTU), with anionic sodium dodecyl sulphate (SDS) and cationic cetlytrimethyl ammonium bromide (CTAB) surfactants were studied using cyclic voltammetry and UV-Visible spectroscopic techniques. The results from both techniques asserted the formation of complex between the drugs and surfactants. In the pre-micellar concentrations, the binding was mainly due to the interactions between the surfactants monomers (electrostatic) and the drug molecules, while in the post-micellar region, drug was encapsulated within the micelle due to electrostatic as well as hydrophobic interactions. The UV-Visible spectroscopic data of the interaction between 5-fluorouracil and the surfactants exhibited an isobestic point which indicated the presence of equilibrium species in bulk and the micellar phase. Binding constant, partition coefficient between bulk and miceller phase, and the number of drug molecules incorporated per micelle were calculated. (author)

STELLAR AGES AND CONVECTIVE CORES IN FIELD MAIN-SEQUENCE STARS: FIRST ASTEROSEISMIC APPLICATION TO TWO KEPLER TARGETS

Energy Technology Data Exchange (ETDEWEB)

Silva Aguirre, V.; Christensen-Dalsgaard, J.; Chaplin, W. J. [Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Basu, S.; Deheuvels, S. [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States); Brandao, I. M.; Cunha, M. S.; Sousa, S. G. [Centro de Astrofisica and Faculdade de Ciencias, Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal); Dogan, G. [High Altitude Observatory, NCAR, P.O. Box 3000, Boulder, CO 80307 (United States); Metcalfe, T. S. [Space Science Institute, Boulder, CO 80301 (United States); Serenelli, A. M.; Garcia, R. A. [Kavli Institute for Theoretical Physics, Santa Barbara, CA 93106 (United States); Ballot, J. [Institut de Recherche en Astrophysique et Planetologie, CNRS, 14 avenue Edouard Belin, F-31400 Toulouse (France); Weiss, A. [Max Planck Institute for Astrophysics, Karl-Schwarzschild-Str. 1, D-85748 Garching bei Muenchen (Germany); Appourchaux, T. [Institut d' Astrophysique Spatiale, Universite Paris Sud-CNRS (UMR8617) Batiment 121, F-91405 Orsay Cedex (France); Casagrande, L. [Research School of Astronomy and Astrophysics, Mount Stromlo Observatory, The Australian National University, ACT 2611 (Australia); Cassisi, S. [INAF-Astronomical Observatory of Teramo, Via M. Maggini sn, I-64100 Teramo (Italy); Creevey, O. L. [Laboratoire Lagrange, Universite de Nice Sophia-Antipolis, CNRS, I-06300 Nice, France. (France); Lebreton, Y. [Observatoire de Paris, GEPI, CNRS UMR 8111, F-92195 Meudon (France); Noels, A. [Institute of Astrophysics and Geophysics, University of Liege, B-4000 Liege (Belgium); and others

2013-06-01

Using asteroseismic data and stellar evolution models we obtain the first detection of a convective core in a Kepler field main-sequence star, putting a stringent constraint on the total size of the mixed zone and showing that extra mixing beyond the formal convective boundary exists. In a slightly less massive target the presence of a convective core cannot be conclusively discarded, and thus its remaining main-sequence lifetime is uncertain. Our results reveal that best-fit models found solely by matching individual frequencies of oscillations corrected for surface effects do not always properly reproduce frequency combinations. Moreover, slightly different criteria to define what the best-fit model is can lead to solutions with similar global properties but very different interior structures. We argue that the use of frequency ratios is a more reliable way to obtain accurate stellar parameters, and show that our analysis in field main-sequence stars can yield an overall precision of 1.5%, 4%, and 10% in radius, mass, and age, respectively. We compare our results with those obtained from global oscillation properties, and discuss the possible sources of uncertainties in asteroseismic stellar modeling where further studies are still needed.

The Physical Driver of the Optical Eigenvector 1 in Quasar Main Sequence

Energy Technology Data Exchange (ETDEWEB)

Panda, Swayamtrupta; Czerny, Bożena [Center for Theoretical Physics, Polish Academy of Sciences, Warsaw (Poland); Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Warsaw (Poland); Wildy, Conor, E-mail: panda@cft.edu.pl [Center for Theoretical Physics, Polish Academy of Sciences, Warsaw (Poland)

2017-11-07

Quasars are complex sources, characterized by broad band spectra from radio through optical to X-ray band, with numerous emission and absorption features. This complexity leads to rich diagnostics. However, Boroson and Green (1992) used Principal Component Analysis (PCA), and with this analysis they were able to show significant correlations between the measured parameters. The leading component, related to Eigenvector 1 (EV1) was dominated by the anticorrelation between the FeII optical emission and [OIII] line and EV1 alone contained 30% of the total variance. It opened a way in defining a quasar main sequence, in close analogy to the stellar main sequence on the Hertzsprung-Russel (HR) diagram (Sulentic et al., 2001). The question still remains which of the basic theoretically motivated parameters of an active nucleus (Eddington ratio, black hole mass, accretion rate, spin, and viewing angle) is the main driver behind the EV1. Here we limit ourselves to the optical waveband, and concentrate on theoretical modeling the FeII to Hβ ratio, and we test the hypothesis that the physical driver of EV1 is the maximum of the accretion disk temperature, reflected in the shape of the spectral energy distribution (SED). We performed computations of the Hβ and optical FeII for a broad range of SED peak position using CLOUDY photoionisation code. We assumed that both Hβ and FeII emission come from the Broad Line Region represented as a constant density cloud in a plane-parallel geometry. We expected that a hotter disk continuum will lead to more efficient production of FeII but our computations show that the FeII to Hβ ratio actually drops with the rise of the disk temperature. Thus either hypothesis is incorrect, or approximations used in our paper for the description of the line emissivity is inadequate.

The Physical Driver of the Optical Eigenvector 1 in Quasar Main Sequence

Directory of Open Access Journals (Sweden)

Swayamtrupta Panda

2017-11-01

Full Text Available Quasars are complex sources, characterized by broad band spectra from radio through optical to X-ray band, with numerous emission and absorption features. This complexity leads to rich diagnostics. However, Boroson and Green (1992 used Principal Component Analysis (PCA, and with this analysis they were able to show significant correlations between the measured parameters. The leading component, related to Eigenvector 1 (EV1 was dominated by the anticorrelation between the FeII optical emission and [OIII] line and EV1 alone contained 30% of the total variance. It opened a way in defining a quasar main sequence, in close analogy to the stellar main sequence on the Hertzsprung-Russel (HR diagram (Sulentic et al., 2001. The question still remains which of the basic theoretically motivated parameters of an active nucleus (Eddington ratio, black hole mass, accretion rate, spin, and viewing angle is the main driver behind the EV1. Here we limit ourselves to the optical waveband, and concentrate on theoretical modeling the FeII to Hβ ratio, and we test the hypothesis that the physical driver of EV1 is the maximum of the accretion disk temperature, reflected in the shape of the spectral energy distribution (SED. We performed computations of the Hβ and optical FeII for a broad range of SED peak position using CLOUDY photoionisation code. We assumed that both Hβ and FeII emission come from the Broad Line Region represented as a constant density cloud in a plane-parallel geometry. We expected that a hotter disk continuum will lead to more efficient production of FeII but our computations show that the FeII to Hβ ratio actually drops with the rise of the disk temperature. Thus either hypothesis is incorrect, or approximations used in our paper for the description of the line emissivity is inadequate.

Systematic main sequence photometry of globular cluster stars for age determination

International Nuclear Information System (INIS)

Alcaino, G.; Liller, W.

1984-01-01

The individual photometric study of the coeval stars in globular clusters presents one of the best observational tests of the stellar evolution theory. Our own globular cluster system provides fundamental clues to the dynamical and chemical evolutionary history of the galaxy, and the study of their ages give a lower limit to the age of the galaxy as well as to that of the universe. The authors have undertaken a systematic research program, and discuss the ages deduced by fitting main sequence photometry to theoretical isochrones of six galactic globular clusters: M4, M22, M30, NGC 288, NGC 3201 and NGC 6397. (Auth.)

VARIABILITY OF DISK EMISSION IN PRE-MAIN SEQUENCE AND RELATED STARS. III. EXPLORING STRUCTURAL CHANGES IN THE PRE-TRANSITIONAL DISK IN HD 169142

Energy Technology Data Exchange (ETDEWEB)

Wagner, Kevin R.; Sitko, Michael L.; Swearingen, Jeremy R.; Champney, Elizabeth H.; Johnson, Alexa N.; Werren, Chelsea [Department of Physics, University of Cincinnati, Cincinnati, OH 45221 (United States); Grady, Carol A. [Eureka Scientific, 2452 Delmer, Suite 100, Oakland, CA 96002 (United States); Whitney, Barbara A. [Department of Astronomy, University of Wisconsin, 475 North CharterStreet, Madison, WI 53706-1582 (United States); Russell, Ray W. [The Aerospace Corporation, Los Angeles, CA 90009 (United States); Schneider, Glenn H. [Steward Observatory, 933 North Cherry Avenue, University of Arizona, Tucson, AZ 85721 (United States); Momose, Munetake [Ibaraki University, 310-0056 Ibaraki, Mito, Bunkyo, 11 (Japan); Muto, Takayuki [Kogakuin University, 1-24-2 Nishishinjuku, Shinjuku, Tokyo 163-8677 (Japan); Inoue, Akio K. [Osaka Sangyo University, College of General Education, 3-1-1 Nakagaito, Daito, Osaka 574-8530 (Japan); Lauroesch, James T.; Hornbeck, Jeremy [University of Louisville Research Foundation, Inc., 2301 South 3rd Street, Louisville, KY 40292 (United States); Brown, Alexander [Center for Astrophysics and Space Astronomy, Astrophysics Research Laboratory, 593 UCB, University of Colorado, Boulder, CO 80309-0593 (United States); Fukagawa, Misato [Department of Earth and Space Science, Graduate School of Science, Osaka University, 1-1, Machikaneyama, Toyonaka, Osaka 560-0043 (Japan); Currie, Thayne M. [Oak Ridge Associated Universities, 100 ORAU Way, Oak Ridge, TN 37830-6218 (United States); Wisniewski, John P. [University of Oklahoma, 660 Parrington Oval, Norman, OK 73019 (United States); Woodgate, Bruce E., E-mail: wagnekr@mail.uc.edu, E-mail: sitkoml@ucmail.uc.edu, E-mail: swearijr@mail.uc.edu, E-mail: ehchampney@gmail.com, E-mail: astefank@andrew.cmu.edu, E-mail: ccwerren@yahoo.com, E-mail: carol.a.grady@nasa.gov, E-mail: bwhitney@astro.wisc.edu, E-mail: Ray.W.Russell@aero.org [NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States)

2015-01-10

We present near-IR (NIR) and far-UV observations of the pre-transitional (gapped) disk in HD 169142 using NASA's Infrared Telescope Facility and Hubble Space Telescope. The combination of our data along with existing data sets into the broadband spectral energy distribution reveals variability of up to 45% between ∼1.5-10 μm over a maximum timescale of 10 yr. All observations known to us separate into two distinct states corresponding to a high near-IR state in the pre-2000 epoch and a low state in the post-2000 epoch, indicating activity within the ≲1 AU region of the disk. Through analysis of the Pa β and Br γ lines in our data we derive a mass accretion rate in 2013 May of M-dot ≈ (1.5-2.7) × 10{sup –9} M {sub ☉} yr{sup –1}. We present a theoretical modeling analysis of the disk in HD 169142 using Monte-Carlo radiative transfer simulation software to explore the conditions and perhaps signs of planetary formation in our collection of 24 yr of observations. We find that shifting the outer edge (r ≈ 0.3 AU) of the inner disk by 0.05 AU toward the star (in simulation of accretion and/or sculpting by forming planets) successfully reproduces the shift in NIR flux. We establish that the ∼40-70 AU dark ring imaged in the NIR by Quanz et al. and Momose et al. and at 7 mm by Osorio et al. may be reproduced with a 30% scaled density profile throughout the region, strengthening the link to this structure being dynamically cleared by one or more planetary mass bodies.

VARIABILITY OF DISK EMISSION IN PRE-MAIN SEQUENCE AND RELATED STARS. III. EXPLORING STRUCTURAL CHANGES IN THE PRE-TRANSITIONAL DISK IN HD 169142

International Nuclear Information System (INIS)

Wagner, Kevin R.; Sitko, Michael L.; Swearingen, Jeremy R.; Champney, Elizabeth H.; Johnson, Alexa N.; Werren, Chelsea; Grady, Carol A.; Whitney, Barbara A.; Russell, Ray W.; Schneider, Glenn H.; Momose, Munetake; Muto, Takayuki; Inoue, Akio K.; Lauroesch, James T.; Hornbeck, Jeremy; Brown, Alexander; Fukagawa, Misato; Currie, Thayne M.; Wisniewski, John P.; Woodgate, Bruce E.

2015-01-01

We present near-IR (NIR) and far-UV observations of the pre-transitional (gapped) disk in HD 169142 using NASA's Infrared Telescope Facility and Hubble Space Telescope. The combination of our data along with existing data sets into the broadband spectral energy distribution reveals variability of up to 45% between ∼1.5-10 μm over a maximum timescale of 10 yr. All observations known to us separate into two distinct states corresponding to a high near-IR state in the pre-2000 epoch and a low state in the post-2000 epoch, indicating activity within the ≲1 AU region of the disk. Through analysis of the Pa β and Br γ lines in our data we derive a mass accretion rate in 2013 May of M-dot ≈ (1.5-2.7) × 10 –9 M ☉ yr –1 . We present a theoretical modeling analysis of the disk in HD 169142 using Monte-Carlo radiative transfer simulation software to explore the conditions and perhaps signs of planetary formation in our collection of 24 yr of observations. We find that shifting the outer edge (r ≈ 0.3 AU) of the inner disk by 0.05 AU toward the star (in simulation of accretion and/or sculpting by forming planets) successfully reproduces the shift in NIR flux. We establish that the ∼40-70 AU dark ring imaged in the NIR by Quanz et al. and Momose et al. and at 7 mm by Osorio et al. may be reproduced with a 30% scaled density profile throughout the region, strengthening the link to this structure being dynamically cleared by one or more planetary mass bodies

Sequence of decommissioning of the main equipment in a central type VVER 440 V-230

International Nuclear Information System (INIS)

Andres, E.; Garcia Ruiz, R.

2014-01-01

IBERDROLA Ingenieria y Construccion S.A.U., leader of consortium with Empresarios Agrupados and INDRA, has developed the Basic Engineering for the decommissioning of contaminated systems and building of a VVER 440 V-230 Nuclear Power Plant, establishing the sequence and methodology for the main equipment fragmentation. For that, it has been designed dry and wet cutting zones to be set up in the area where steam generators, main cooling pumps and pressurizer are located; these components will be dismantled previously. (Author)

On the determination of the He abundance distribution in globular clusters from the width of the main sequence

Science.gov (United States)

Cassisi, Santi; Salaris, Maurizio; Pietrinferni, Adriano; Hyder, David

2017-01-01

One crucial piece of information to study the origin of multiple stellar populations in globular clusters is the range of initial helium abundances ΔY amongst the sub-populations hosted by each cluster. These estimates are commonly obtained by measuring the width in colour of the unevolved main sequence in an optical colour-magnitude diagram (CMD). The measured colour spread is then compared with predictions from theoretical stellar isochrones with varying initial He abundances to determine ΔY. The availability of UV/optical magnitudes, thanks to the Hubble Space Telescope UV Legacy Survey of Galactic GCs project, will allow the homogeneous determination of ΔY for a large Galactic globular cluster sample. From a theoretical point of view, accurate UV CMDs can efficiently disentangle the various sub-populations, and main sequence colour differences in the ACS F606W - (F606W - F814W) diagram allow an estimate of ΔY. We demonstrate that from a theoretical perspective, the (F606W - F814W) colour is an extremely reliable He-abundance indicator. The derivative dY/d(F606W - F814W), computed at a fixed luminosity along the unevolved main sequence, is largely insensitive to the physical assumptions made in stellar model computations, being more sensitive to the choice of the bolometric correction scale, and is only slightly dependent on the adopted set of stellar models. From a theoretical point of view, the (F606W - F814W) colour width of the cluster main sequence is therefore a robust diagnostic of the ΔY range.

Magnetic inhibition of convection and the fundamental properties of low-mass stars. II. Fully convective main-sequence stars

Energy Technology Data Exchange (ETDEWEB)

Feiden, Gregory A. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Chaboyer, Brian, E-mail: gregory.a.feiden@gmail.com, E-mail: brian.chaboyer@dartmouth.edu [Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, NH 03755 (United States)

2014-07-01

We examine the hypothesis that magnetic fields are inflating the radii of fully convective main-sequence stars in detached eclipsing binaries (DEBs). The magnetic Dartmouth stellar evolution code is used to analyze two systems in particular: Kepler-16 and CM Draconis. Magneto-convection is treated assuming stabilization of convection and also by assuming reductions in convective efficiency due to a turbulent dynamo. We find that magnetic stellar models are unable to reproduce the properties of inflated fully convective main-sequence stars, unless strong interior magnetic fields in excess of 10 MG are present. Validation of the magnetic field hypothesis given the current generation of magnetic stellar evolution models therefore depends critically on whether the generation and maintenance of strong interior magnetic fields is physically possible. An examination of this requirement is provided. Additionally, an analysis of previous studies invoking the influence of star spots is presented to assess the suggestion that star spots are inflating stars and biasing light curve analyses toward larger radii. From our analysis, we find that there is not yet sufficient evidence to definitively support the hypothesis that magnetic fields are responsible for the observed inflation among fully convective main-sequence stars in DEBs.

Metallicity and ultraviolet excesses of late main sequence stars

International Nuclear Information System (INIS)

Suchkov, A.A.; Marsakov, V.A.; Shevelev, Yu.G.

1987-01-01

The comparison of the characteristics of ultraviolet (UV) excesses δ(U-B) and metallicity [Fe/H] distributions of F, G, and K dwarfs reveals a number of discrepancies. It is shown that they can be eliminated if we assume that UV excesses of K and late G dwarfs, and [Fe/H] values from detailed analysis for F dwarfs are underestimated. Such an assumption enables to account for low values of for F, K and late G dwarfs, and for the difference of the free terms in the metallicity - UV-excess relation for these stars as compared to early G dwarfs. In this case the F5-F9 dwarfs turn out to be more metal-rich (by 0.1 in [Fe/H]) than G and K dwarfs, and the metallicity of the Hyades cluster turns out to be larger than the solar one, [Fe/H] Hyades =+0.1. The ''conditional'' metallicity - UV-excess calibrations are obtained for four groups of main-sequence stars: F5-F9, G0-G4, G5-G9, K0-K5

An assessment of time involved in pre-test case review and counseling for a whole genome sequencing clinical research program.

Science.gov (United States)

Williams, Janet L; Faucett, W Andrew; Smith-Packard, Bethanny; Wagner, Monisa; Williams, Marc S

2014-08-01

Whole genome sequencing (WGS) is being used for evaluation of individuals with undiagnosed disease of suspected genetic origin. Implementing WGS into clinical practice will place an increased burden upon care teams with regard to pre-test patient education and counseling about results. To quantitate the time needed for appropriate pre-test evaluation of participants in WGS testing, we documented the time spent by our clinical research group on various activities related to program preparation, participant screening, and consent prior to WGS. Participants were children or young adults with autism, intellectual or developmental disability, and/or congenital anomalies, who have remained undiagnosed despite previous evaluation, and their biologic parents. Results showed that significant time was spent in securing allocation of clinical research space to counsel participants and families, and in acquisition and review of participant's medical records. Pre-enrollment chart review identified two individuals with existing diagnoses resulting in savings of $30,000 for the genome sequencing alone, as well as saving hours of personnel time for genome interpretation and communication of WGS results. New WGS programs should plan for costs associated with additional pre-test administrative planning and patient evaluation time that will be required to provide high quality care.

THE CONTRIBUTIONS OF INTERACTIVE BINARY STARS TO DOUBLE MAIN-SEQUENCE TURNOFFS AND DUAL RED CLUMP OF INTERMEDIATE-AGE STAR CLUSTERS

International Nuclear Information System (INIS)

Yang Wuming; Bi Shaolan; Tian Zhijia; Li Tanda; Liu Kang; Meng Xiangcun

2011-01-01

Double or extended main-sequence turnoffs (DMSTOs) and dual red clump (RC) were observed in intermediate-age clusters, such as in NGC 1846 and 419. The DMSTOs are interpreted as that the cluster has two distinct stellar populations with differences in age of about 200-300 Myr but with the same metallicity. The dual RC is interpreted as a result of a prolonged star formation. Using a stellar population-synthesis method, we calculated the evolution of a binary-star stellar population. We found that binary interactions and merging can reproduce the dual RC in the color-magnitude diagrams of an intermediate-age cluster, whereas in actuality only a single population exists. Moreover, the binary interactions can lead to an extended main-sequence turnoff (MSTO) rather than DMSTOs. However, the rest of the main sequence, subgiant branch, and first giant branch are hardly spread by the binary interactions. Part of the observed dual RC and extended MSTO may be the results of binary interactions and mergers.

Common Warm Dust Temperatures Around Main Sequence Stars

Science.gov (United States)

Morales, Farisa; Rieke, George; Werner, Michael; Stapelfeldt, Karl; Bryden, Geoffrey; Su, Kate

2011-01-01

We compare the properties of warm dust emission from a sample of main-sequence A-type stars (B8-A7) to those of dust around solar-type stars (F5-KO) with similar Spitzer Space Telescope Infrared Spectrograph/MIPS data and similar ages. Both samples include stars with sources with infrared spectral energy distributions that show evidence of multiple components. Over the range of stellar types considered, we obtain nearly the same characteristic dust temperatures (∼ 190 K and ∼60 K for the inner and outer dust components, respectively)-slightly above the ice evaporation temperature for the inner belts. The warm inner dust temperature is readily explained if populations of small grains are being released by sublimation of ice from icy planetesimals. Evaporation of low-eccentricity icy bodies at ∼ 150 K can deposit particles into an inner/warm belt, where the small grains are heated to dust Temperatures of -190 K. Alternatively, enhanced collisional processing of an asteroid belt-like system of parent planetesimals just interior to the snow line may account for the observed uniformity in dust temperature. The similarity in temperature of the warmer dust across our B8-KO stellar sample strongly suggests that dust-producing planetesimals are not found at similar radial locations around all stars, but that dust production is favored at a characteristic temperature horizon.

Accelerated high-resolution 3D magnetic resonance spectroscopic imaging in the brain At 7 T

International Nuclear Information System (INIS)

Hangel, G.

2015-01-01

With the announcement of the first series of magnetic resonance (MR) scanners with a field strength of 7 Tesla (T) intended for clinical practice, the development of high-performance sequences for higher field strengths has gained importance. Magnetic resonance spectroscopic imaging (MRSI) in the brain currently offers the unique ability to spatially resolve the distribution of multiple metabolites simultaneously. Its big diagnostic potential could be applied to many clinical protocols, for example the assessment of tumour treatment or progress of Multiple Sclerosis. Moving to ultra-high fields like 7 T has the main benefits of increased signal-to-noise ratio (SNR) and improved spectral quality, but brings its own challenges due to stronger field inhomogeneities. Necessary for a robust, flexible and useful MRSI sequence in the brain are high resolutions, shortened measurement times, the possibility for 3D-MRSI and the suppression of spectral contamination by trans-cranial lipids. This thesis addresses these limitations and proposes Hadamard spectroscopic imaging (HSI) as solution for multi-slice MRSI, the application of generalized autocalibrating partially parallel acquisition (GRAPPA) and spiral trajectories for measurement acceleration, non-selective inversion recovery (IR) lipid-suppression as well as combinations of these methods. Further, the optimisation of water suppression for 7 T systems and the acquisition of ultra-high resolution (UHR)-MRSI are discussed. In order to demonstrate the clinical feasibility of these approaches, MRSI measurement results of a glioma patient are presented. The discussion of the obtained results in the context of the state-of-art in 7 T MRSI in the brain, possible future applications as well as potential further improvements of the MRSI sequences conclude this thesis. (author) [de

The hydrophobic core of twin-arginine signal sequences orchestrates specific binding to Tat-pathway related chaperones.

Directory of Open Access Journals (Sweden)

Anitha Shanmugham

Full Text Available Redox enzyme maturation proteins (REMPs bind pre-proteins destined for translocation across the bacterial cytoplasmic membrane via the twin-arginine translocation system and enable the enzymatic incorporation of complex cofactors. Most REMPs recognize one specific pre-protein. The recognition site usually resides in the N-terminal signal sequence. REMP binding protects signal peptides against degradation by proteases. REMPs are also believed to prevent binding of immature pre-proteins to the translocon. The main aim of this work was to better understand the interaction between REMPs and substrate signal sequences. Two REMPs were investigated: DmsD (specific for dimethylsulfoxide reductase, DmsA and TorD (specific for trimethylamine N-oxide reductase, TorA. Green fluorescent protein (GFP was genetically fused behind the signal sequences of TorA and DmsA. This ensures native behavior of the respective signal sequence and excludes any effects mediated by the mature domain of the pre-protein. Surface plasmon resonance analysis revealed that these chimeric pre-proteins specifically bind to the cognate REMP. Furthermore, the region of the signal sequence that is responsible for specific binding to the corresponding REMP was identified by creating region-swapped chimeric signal sequences, containing parts of both the TorA and DmsA signal sequences. Surprisingly, specificity is not encoded in the highly variable positively charged N-terminal region of the signal sequence, but in the more similar hydrophobic C-terminal parts. Interestingly, binding of DmsD to its model substrate reduced membrane binding of the pre-protein. This property could link REMP-signal peptide binding to its reported proofreading function.

Identifying the Young Low-mass Stars within 25 pc. I. Spectroscopic Observations

Science.gov (United States)

Shkolnik, Evgenya; Liu, Michael C.; Reid, I. Neill

2009-07-01

We have completed a high-resolution (R ≈ 60,000) optical spectroscopic survey of 185 nearby M dwarfs identified using ROSAT data to select active, young objects with fractional X-ray luminosities comparable to or greater than Pleiades members. Our targets are drawn from the NStars 20 pc census and the Moving-M sample with distances determined from parallaxes or spectrophotometric relations. We limited our sample to 25 pc from the Sun, prior to correcting for pre-main-sequence overluminosity or binarity. Nearly half of the resulting M dwarfs are not present in the Gliese catalog and have no previously published spectral types. We identified 30 spectroscopic binaries (SBs) from the sample, which have strong X-ray emission due to tidal spin-up rather than youth. This is equivalent to a 16% SB fraction, with at most a handful of undiscovered SBs. We estimate upper limits on the age of the remaining M dwarfs using spectroscopic youth indicators such as surface gravity-sensitive indices (CaH and K I). We find that for a sample of field stars with no metallicity measurements, a single CaH gravity index may not be sufficient, as higher metallicities mimic lower gravity. This is demonstrated in a subsample of metal-rich radial velocity (RV) standards, which appear to have low surface gravity as measured by the CaH index, yet show no other evidence of youth. We also use additional youth diagnostics such as lithium absorption and strong Hα emission to set more stringent age limits. Eleven M dwarfs with no Hα emission or absorption are likely old (>400 Myr) and were caught during an X-ray flare. We estimate that our final sample of the 144 youngest and nearest low-mass objects in the field is less than 300 Myr old, with 30% of them being younger than 150 Myr and four very young (lap10 Myr), representing a generally untapped and well-characterized resource of M dwarfs for intensive planet and disk searches. Based on observations collected at the W. M. Keck Observatory and

Effect of Generalized Uncertainty Principle on Main-Sequence Stars and White Dwarfs

Directory of Open Access Journals (Sweden)

Mohamed Moussa

2015-01-01

Full Text Available This paper addresses the effect of generalized uncertainty principle, emerged from different approaches of quantum gravity within Planck scale, on thermodynamic properties of photon, nonrelativistic ideal gases, and degenerate fermions. A modification in pressure, particle number, and energy density are calculated. Astrophysical objects such as main-sequence stars and white dwarfs are examined and discussed as an application. A modification in Lane-Emden equation due to a change in a polytropic relation caused by the presence of quantum gravity is investigated. The applicable range of quantum gravity parameters is estimated. The bounds in the perturbed parameters are relatively large but they may be considered reasonable values in the astrophysical regime.

Testing Scaling Relations for Solar-like Oscillations from the Main Sequence to Red Giants Using Kepler Data

DEFF Research Database (Denmark)

Huber, D.; Bedding, T.R.; Stello, D.

2011-01-01

), and oscillation amplitudes. We show that the difference of the Δν-νmax relation for unevolved and evolved stars can be explained by different distributions in effective temperature and stellar mass, in agreement with what is expected from scaling relations. For oscillation amplitudes, we show that neither (L/M) s......We have analyzed solar-like oscillations in ~1700 stars observed by the Kepler Mission, spanning from the main sequence to the red clump. Using evolutionary models, we test asteroseismic scaling relations for the frequency of maximum power (νmax), the large frequency separation (Δν...... scaling nor the revised scaling relation by Kjeldsen & Bedding is accurate for red-giant stars, and demonstrate that a revised scaling relation with a separate luminosity-mass dependence can be used to calculate amplitudes from the main sequence to red giants to a precision of ~25%. The residuals show...

New Insights into the Formation of the Blue Main Sequence in NGC 1850

Science.gov (United States)

Yang, Yujiao; Li, Chengyuan; Deng, Licai; de Grijs, Richard; Milone, Antonino P.

2018-06-01

Recent discoveries of bimodal main sequences (MSs) associated with young clusters (with ages ≲1 Gyr) in the Magellanic Clouds have drawn a lot of attention. One of the prevailing formation scenarios attributes these split MSs to a bimodal distribution in stellar rotation rates, with most stars belonging to a rapidly rotating population. In this scenario, only a small fraction of stars populating a secondary blue sequence are slowly or non-rotating stars. Here, we focus on the blue MS in the young cluster NGC 1850. We compare the cumulative number fraction of the observed blue-MS stars to that of the high-mass-ratio binary systems at different radii. The cumulative distributions of both populations exhibit a clear anti-correlation, characterized by a highly significant Pearson coefficient of ‑0.97. Our observations are consistent with the possibility that blue-MS stars are low-mass-ratio binaries, and therefore their dynamical disruption is still ongoing. High-mass-ratio binaries, on the other hand, are more centrally concentrated.

Features of the use of charge-coupled devices in emission spectroscopic analysis

International Nuclear Information System (INIS)

Livshits, A.M.; Peleznev, A.V.

1993-01-01

Multielement radiation receivers based on linear charge-coupled photodiode devices have become more aand more widely used recently in spectroscopic analysis. The main feature of such receivers is their ability to record not only the intensity of the incident light flux, but also its spatial distribution. This article considers the advantages and disadvantages of charge-coupled devices when used in emission spectroscopic analysis. The main methods nd devices employed for this purpose and discussed here can be divided into four types: photographic photometry, visual styloscopy, quantometry, and successive analysis. 4 refs., 1 fig

Determination of the protection efficacy and homogeneity of the distribution of sunscreens applied onto skin pre-treated with cosmetic products.

Science.gov (United States)

Weigmann, Hans-Jürgen; de Sainte Claire, Maude Suisse; Schanzer, Sabine; Patzelt, Alexa; Meinke, Martina; Antoniou, Christina; Sterry, Wolfram; Lademann, Jürgen

2012-05-01

The efficacy of sunscreens depends decisively on the homogeneity of its distribution on the skin surface, which is sensitively reflected by two spectroscopic data - the factor of inhomogeneity and the sum transmission - measured after tape stripping. The aim of this study was to investigate the influence of a skin pre-treatment with body lotion on the layout of the formulations. Six healthy volunteers were pre-treated using the body lotion, Nivea Body (Beiersdorf AG, Hamburg, Germany). The sunscreen was an oil/water (o/w) emulsion, Roc SPF 8 (RoC SA, Paris, France). The tape stripped tesa films were measured with a modified UV/VIS spectrometer Lambda 5 (PerkinElmer, Frankfurt/Main, Germany), the data of which were used to calculate both measurands. The obtained results made clear that the original spectroscopic data must be corrected taking into account the changed amounts of horny layer particles removed with the individual tape strips after pre-treatment. As a consequence of the correction, the factors of inhomogeneity as well as the sum transmissions confirm a more homogeneous distribution of the applied sunscreen. The findings confirm that the applied method is well suited to obtain information on the distribution of topically applied substances, and furthermore that the influence of the pre-treatment of the skin with the body lotion enhances the homogeneity of distribution and thus the sunscreen efficacy. © 2011 John Wiley & Sons A/S.

Luminosity and Intrinsic Color Calibration of Main-Sequence Stars With 2Mass Photometry: All Sky Local Extinction

Directory of Open Access Journals (Sweden)

Knude Jens

2003-12-01

Full Text Available We present a new color index vs. absolute magnitude calibration of 2MASS JHK photometry. For the A0 to ~G5 and M segments of the main sequence information on the amount of interstellar extinction and its location in space may be obtained.

Discovery of Extended Main-sequence Turnoffs in Four Young Massive Clusters in the Magellanic Clouds

Energy Technology Data Exchange (ETDEWEB)

Li, Chengyuan [Department of Physics and Astronomy, Macquarie University, Sydney, NSW 2109 (Australia); De Grijs, Richard [Kavli Institute for Astronomy and Astrophysics and Department of Astronomy, Peking University, Yi He Yuan Lu 5, Hai Dian District, Beijing 100871 (China); Deng, Licai [Key Laboratory for Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012 (China); Milone, Antonino P. [Research School of Astronomy and Astrophysics, Australian National University, Mt. Stromlo Observatory, Cotter Road, Weston, ACT 2611 (Australia)

2017-08-01

An increasing number of young massive clusters (YMCs) in the Magellanic Clouds have been found to exhibit bimodal or extended main sequences (MSs) in their color–magnitude diagrams (CMDs). These features are usually interpreted in terms of a coeval stellar population with different stellar rotational rates, where the blue and red MS stars are populated by non- (or slowly) and rapidly rotating stellar populations, respectively. However, some studies have shown that an age spread of several million years is required to reproduce the observed wide turnoff regions in some YMCs. Here we present the ultraviolet–visual CMDs of four Large and Small Magellanic Cloud YMCs, NGC 330, NGC 1805, NGC 1818, and NGC 2164, based on high-precision Hubble Space Telescope photometry. We show that they all exhibit extended main-sequence turnoffs (MSTOs). The importance of age spreads and stellar rotation in reproducing the observations is investigated. The observed extended MSTOs cannot be explained by stellar rotation alone. Adopting an age spread of 35–50 Myr can alleviate this difficulty. We conclude that stars in these clusters are characterized by ranges in both their ages and rotation properties, but the origin of the age spread in these clusters remains unknown.

Spectroscopic failures in photometric redshift calibration: cosmological biases and survey requirements

Energy Technology Data Exchange (ETDEWEB)

Cunha, Carlos E. [KIPAC, Menlo Park; Huterer, Dragan [Michigan U.; Lin, Huan [Fermilab; Busha, Michael T. [Zurich U.; Wechsler, Risa H. [SLAC

2014-10-11

We use N-body-spectro-photometric simulations to investigate the impact of incompleteness and incorrect redshifts in spectroscopic surveys to photometric redshift training and calibration and the resulting effects on cosmological parameter estimation from weak lensing shear-shear correlations. The photometry of the simulations is modeled after the upcoming Dark Energy Survey and the spectroscopy is based on a low/intermediate resolution spectrograph with wavelength coverage of 5500{\\AA} < {\\lambda} < 9500{\\AA}. The principal systematic errors that such a spectroscopic follow-up encounters are incompleteness (inability to obtain spectroscopic redshifts for certain galaxies) and wrong redshifts. Encouragingly, we find that a neural network-based approach can effectively describe the spectroscopic incompleteness in terms of the galaxies' colors, so that the spectroscopic selection can be applied to the photometric sample. Hence, we find that spectroscopic incompleteness yields no appreciable biases to cosmology, although the statistical constraints degrade somewhat because the photometric survey has to be culled to match the spectroscopic selection. Unfortunately, wrong redshifts have a more severe impact: the cosmological biases are intolerable if more than a percent of the spectroscopic redshifts are incorrect. Moreover, we find that incorrect redshifts can also substantially degrade the accuracy of training set based photo-z estimators. The main problem is the difficulty of obtaining redshifts, either spectroscopically or photometrically, for objects at z > 1.3. We discuss several approaches for reducing the cosmological biases, in particular finding that photo-z error estimators can reduce biases appreciably.

Carbon, nitrogen, and oxygen abundances in main-sequence stars. II. 20 F and G stars

International Nuclear Information System (INIS)

Clegg, R.E.S.; Lambert, D.L.; Tomkin, J.

1981-01-01

High-resolution Reticon spectra of red and near-infrared C I, N I, and O I lines have been analyzed to determine C, N, and O abundances in a sample of 20 F and G main-sequence stars. Their iron abundances, which have been determined from analysis of additional Reticon spectra of red Fe I lines, cover the range -0.9< or =[Fe/H]< or =+0.4. Sulfur abundances have also been obtained

The environmental impacts on the star formation main sequence: An Hα study of the newly discovered rich cluster at z = 1.52

Energy Technology Data Exchange (ETDEWEB)

Koyama, Yusei; Kodama, Tadayuki; Tadaki, Ken-ichi; Hayashi, Masao [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Tanaka, Ichi [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A' ohoku Place, Hilo, HI 96720 (United States); Shimakawa, Rhythm, E-mail: koyama.yusei@nao.ac.jp [Department of Astronomical Science, The Graduate University for Advanced Studies, Mitaka, Tokyo 181-8588 (Japan)

2014-07-01

We report the discovery of a strong over-density of galaxies in the field of a radio galaxy at z = 1.52 (4C 65.22) based on our broadband and narrow-band (Hα) photometry with the Subaru Telescope. We find that Hα emitters are located in the outskirts of the density peak (cluster core) dominated by passive red-sequence galaxies. This resembles the situation in lower-redshift clusters, suggesting that the newly discovered structure is a well-evolved rich galaxy cluster at z = 1.5. Our data suggest that the color-density and stellar mass-density relations are already in place at z ∼ 1.5, mostly driven by the passive red massive galaxies residing within r{sub c} ≲ 200 kpc from the cluster core. These environmental trends almost disappear when we consider only star-forming (SF) galaxies. We do not find SFR-density or SSFR-density relations amongst SF galaxies, and the location of the SF main sequence does not significantly change with environment. Nevertheless, we find a tentative hint that star-bursting galaxies (up-scattered objects from the main sequence) are preferentially located in a small group at ∼1 Mpc away from the main body of the cluster. We also argue that the scatter of the SF main sequence could be dependent on the distance to the nearest neighboring galaxy.

Biofluid infrared spectro-diagnostics: pre-analytical considerations for clinical applications.

Science.gov (United States)

Lovergne, L; Bouzy, P; Untereiner, V; Garnotel, R; Baker, M J; Thiéfin, G; Sockalingum, G D

2016-06-23

Several proof-of-concept studies on the vibrational spectroscopy of biofluids have demonstrated that the methodology has promising potential as a clinical diagnostic tool. However, these studies also show that there is a lack of a standardised protocol in sample handling and preparation prior to spectroscopic analysis. One of the most important sources of analytical errors is the pre-analytical phase. For the technique to be translated into clinics, it is clear that a very strict protocol needs to be established for such biological samples. This study focuses on some of the aspects of the pre-analytical phase in the development of the high-throughput Fourier Transform Infrared (FTIR) spectroscopy of some of the most common biofluids such as serum, plasma and bile. Pre-analytical considerations that can impact either the samples (solvents, anti-coagulants, freeze-thaw cycles…) and/or spectroscopic analysis (sample preparation such as drying, deposit methods, volumes, substrates, operators dependence…) and consequently the quality and the reproducibility of spectral data will be discussed in this report.

MR pulse sequences for selective relaxation time measurements: a phantom study

DEFF Research Database (Denmark)

Thomsen, C; Jensen, K E; Jensen, M

1990-01-01

a Siemens Magnetom wholebody magnetic resonance scanner operating at 1.5 Tesla was used. For comparison six imaging pulse sequences for relaxation time measurements were tested on the same phantom. The spectroscopic pulse sequences all had an accuracy better than 10% of the reference values....

NGC 1866: First Spectroscopic Detection of Fast-rotating Stars in a Young LMC Cluster

Energy Technology Data Exchange (ETDEWEB)

Dupree, A. K.; Dotter, A.; Johnson, C. I. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Marino, A. F.; Milone, A. P. [Australian National University, The Research School of Astronomy and Astrophysics, Mount Stromlo Observatory, Weston Creek, ACT 2611 (Australia); Bailey, J. I. III [Leiden Observatory, Niels Bohrweg 2, NL-2333 CA Leiden (Netherlands); Crane, J. D. [The Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Mateo, M. [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States); Olszewski, E. W. [The University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States)

2017-09-01

High-resolution spectroscopic observations were taken of 29 extended main-sequence turnoff (eMSTO) stars in the young (∼200 Myr) Large Magellanic Cloud (LMC) cluster, NGC 1866, using the Michigan/ Magellan Fiber System and MSpec spectrograph on the Magellan -Clay 6.5 m telescope. These spectra reveal the first direct detection of rapidly rotating stars whose presence has only been inferred from photometric studies. The eMSTO stars exhibit H α emission (indicative of Be-star decretion disks), others have shallow broad H α absorption (consistent with rotation ≳150 km s{sup −1}), or deep H α core absorption signaling lower rotation velocities (≲150 km s{sup −1}). The spectra appear consistent with two populations of stars—one rapidly rotating, and the other, younger and slowly rotating.

THE GALACTIC O-STAR SPECTROSCOPIC SURVEY (GOSSS). II. BRIGHT SOUTHERN STARS

International Nuclear Information System (INIS)

Sota, A.; Apellániz, J. Maíz; Alfaro, E. J.; Morrell, N. I.; Barbá, R. H.; Arias, J. I.; Walborn, N. R.; Gamen, R. C.

2014-01-01

We present the second installment of GOSSS, a massive spectroscopic survey of Galactic O stars, based on new homogeneous, high signal-to-noise ratio, R ∼ 2500 digital observations from both hemispheres selected from the Galactic O-Star Catalog (GOSC). In this paper we include bright stars and other objects drawn mostly from the first version of GOSC, all of them south of δ = –20°, for a total number of 258 O stars. We also revise the northern sample of Paper I to provide the full list of spectroscopically classified Galactic O stars complete to B = 8, bringing the total number of published GOSSS stars to 448. Extensive sequences of exceptional objects are given, including the early Of/WN, O Iafpe, Ofc, ON/OC, Onfp, Of?p, and Oe types, as well as double/triple-lined spectroscopic binaries. The new spectral subtype O9.2 is also discussed. The magnitude and spatial distributions of the observed sample are analyzed. We also present new results from OWN, a multi-epoch high-resolution spectroscopic survey coordinated with GOSSS that is assembling the largest sample of Galactic spectroscopic massive binaries ever attained. The OWN data combined with additional information on spectroscopic and visual binaries from the literature indicate that only a very small fraction (if any) of the stars with masses above 15-20 M ☉ are born as single systems. In the future we will publish the rest of the GOSSS survey, which is expected to include over 1000 Galactic O stars

Chemically Dissected Rotation Curves of the Galactic Bulge from Main-sequence Proper Motions

Science.gov (United States)

Clarkson, William I.; Calamida, Annalisa; Sahu, Kailash C.; Brown, Thomas M.; Gennaro, Mario; Avila, Roberto J.; Valenti, Jeff; Debattista, Victor P.; Rich, R. Michael; Minniti, Dante; Zoccali, Manuela; Aufdemberge, Emily R.

2018-05-01

We report results from an exploratory study implementing a new probe of Galactic evolution using archival Hubble Space Telescope imaging observations. Precise proper motions are combined with photometric relative metallicity and temperature indices, to produce the proper-motion rotation curves of the Galactic bulge separately for metal-poor and metal-rich main-sequence samples. This provides a “pencil-beam” complement to large-scale wide-field surveys, which to date have focused on the more traditional bright giant branch tracers. We find strong evidence that the Galactic bulge rotation curves drawn from “metal-rich” and “metal-poor” samples are indeed discrepant. The “metal-rich” sample shows greater rotation amplitude and a steeper gradient against line-of-sight distance, as well as possibly a stronger central concentration along the line of sight. This may represent a new detection of differing orbital anisotropy between metal-rich and metal-poor bulge objects. We also investigate selection effects that would be implied for the longitudinal proper-motion cut often used to isolate a “pure-bulge” sample. Extensive investigation of synthetic stellar populations suggests that instrumental and observational artifacts are unlikely to account for the observed rotation curve differences. Thus, proper-motion-based rotation curves can be used to probe chemodynamical correlations for main-sequence tracer stars, which are orders of magnitude more numerous in the Galactic bulge than the bright giant branch tracers. We discuss briefly the prospect of using this new tool to constrain detailed models of Galactic formation and evolution. Based on observations made with the NASA/ESA Hubble Space Telescope and obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

Pre-Processing and Modeling Tools for Bigdata

Directory of Open Access Journals (Sweden)

Hashem Hadi

2016-09-01

Full Text Available Modeling tools and operators help the user / developer to identify the processing field on the top of the sequence and to send into the computing module only the data related to the requested result. The remaining data is not relevant and it will slow down the processing. The biggest challenge nowadays is to get high quality processing results with a reduced computing time and costs. To do so, we must review the processing sequence, by adding several modeling tools. The existing processing models do not take in consideration this aspect and focus on getting high calculation performances which will increase the computing time and costs. In this paper we provide a study of the main modeling tools for BigData and a new model based on pre-processing.

Spectroscopic methods for detection of impurities in water

Science.gov (United States)

Strashnikova, Natalia V.; Papiashvili, Nona; Cohen-Luria, Rivka; Mark, Shlomo; Shilon, Guy; Khankin, Daniel; Kalisky, Yehoshua; Kalisky, Ofra; Parola, Abraham H.

2011-11-01

Optical photoluminescence spectroscopic method for detection of impurities, hazardous materials, pesticides, and pollutants in water resources, both qualitatively and quantitatively, is presented. The method is based on synchronous fluorescence spectroscopy (SFS) of organic aromatic compounds, or poly-aromatic hydrocarbons (PAH), and is carried out by following simultaneously their excitation and emission spectra. The full excitation emission matrix (EEM) generated in this way provides a 2-D and 3-D fluorescence map of the tested sample and the diagonals through the axes origin provide the synchronous fluorescence spectra at a constant wavelengths differences between the emission and excitation wavelengths, thus enabling multitude components identification. This map contains all the relevant spectroscopic information of the tested sample, and serves as a unique "fingerprint" with a very specific and accurate identification. When compared with pre-determined spectra and calibration curves from a "databank", there is a one-toone correspondence between the image and the specific compound, and it can be identified accurately both qualitatively and quantitatively. This method offers several significant advantages, and it provides a sensitive (ppm detection level), accurate and simple spectroscopic tool to monitor impurities and pollutants in water. The design and performance of the spectrofluorimeter prototype, as well as the software development and analysis of chemical organic compounds and mixtures in water will be discussed in this paper.

IRAS colors of carbon stars - An optical spectroscopic test

International Nuclear Information System (INIS)

Cohen, M.; Wainscoat, R.J.; Walker, H.J.; Volk, K.; Schwartz, D.E.

1989-01-01

Optical spectra are obtained of 57 photographic counterparts to IRAS sources not previously studied spectroscopically, and expected on the basis of their IRAS colors to be M or C type stars. Confirmed carbon stars are found only in a restricted range of 12-25 index, and constitute a striking vertical sequence in the 12-25-60 micron color-color diagram. This sequence is in accord with evolutionary models for AGB stars that convert M into C stars by dredge-up, and follow loops in the color-color plane. Optically visible and optically invisible carbon stars occupy different color-color locations consistent with their representations of different evolutionary states in the life of relatively low-mass stars. 16 refs

Spectroscopic characterization of extrasolar planets from ground-, space- and airborne-based observatories

Science.gov (United States)

Angerhausen, Daniel

2010-11-01

This thesis deals with techniques and results of observations of exoplanets from several platforms. In this work I present and then attempt solutions to particular issues and problems connected to ground- and space-based approaches to spectroscopic characterization of extrasolar planets. Furthermore, I present the future prospects of the airborne observatory, SOFIA, in this field of astronomy. The first part of this thesis covers results of an exploratory study to use near-infrared integral-field-spectroscopy to observe transiting extrasolar planets. I demonstrate how adaptive-optics assisted integral field spectroscopy compares with other spectroscopic techniques currently applied, foremost being slit spectroscopy. An advanced reduction method using elements of a spectral-differential decorrelation and optimized observation strategies is discussed. This concept was tested with K-Band time series observations of secondary eclipses of HD 209458b and HD 189733b obtained with the SINFONI at the Very Large Telescope (VLT), at spectral resolution of R~3000. In ground-based near infrared (NIR) observations, there is considerable likelihood of confusion between telluric absorption features and spectral features in the targeted object. I describe a detailed method that can cope with such confusion by a forward modelling approach employing Earth transmission models. In space-based transit spectroscopy with Hubble's NICMOS instrument, the main source of systematic noise is the perturbation in the instrument's configuration due to the near Earth orbital motion of the spacecraft. I present an extension to a pre-existing data analysis sequence that has allowed me to extract a NIR transmission spectrum of the hot-Neptune class planet GJ 436b from a data set that was highly corrupted by the above mentioned effects. Satisfyingly, I was able to obtain statistical consistency in spectra (acquired over a broad wavelength grid) over two distinct observing visits by HST. Earlier

Principles of spectroscopic diagnostics of a plasma with oscillating electric fields

International Nuclear Information System (INIS)

Oks, E.A.

1986-01-01

Three types of main principles of spectroscopic diagnosis of the plasma with quasimonochromatic electric fields (QEF) are considered. Principles based on the effects intersectionally depending on the parameters of QEF and the plasma medium are considered. Occurrence of depressions or dips in the profiles of spectral lines is the most important effect among others. Principles based on the nonlinear theory of plasma and laser sattelites of spectral lines as well as laser-spectroscopic diagnosis of QEF in the plasma are considered

Pre-aspiration in Welsh English: a case study of Aberystwyth

DEFF Research Database (Denmark)

Hejná, Michaela

-aspiration would be manifested as a h sound inserted in the following words as indicated: paht, peht, piht, poht, puht, mahp, mahtt, mahck, ohff, mohth, mahss, mahsh. Because the sound is understudied in English, the work focuses on what other sounds condition the presence of the phenomenon and its duration......Lay abstract This thesis examines pre-aspiration in English spoken in Aberystwyth, mid Wales. Pre-aspiration is a sound very similar to h (as in honey), and it can be found mainly in the sequences of vowels (a, e, i, o, u, etc.) and certain consonants (p, t, k, f, th, s, sh). In English, pre......, if it is sensitive to social factors such as age or gender as well, and it suggests some implications for sound changes including pre-aspiration. Chapter 1 summarises the questions addressed in this thesis and outlines where this work is positioned with respect to our current knowledge of the phenomenon...

Development of an Eccentric CAM Based Active Pre-Alignment System for the CLIC Main Beam Quadrupole Magnet

CERN Document Server

Lackner, F; Collette, C; Mainaud Durand, H; Hauviller, C; Kemppinen, J; Leuxe, R

2010-01-01

CLIC (Compact Linear Collider) is a study for a future electron-positron collider that would allow physicists to explore a new energy region beyond the capabilities of today's particle accelerators. The demanding transverse and vertical beam sizes and emittance specifications are resulting in stringent alignment and a nanometre stability requirement. In the current feasibility study, the main beam quadrupole magnets have to be actively pre-aligned with a precision of 1 µm in 5 degrees of freedom (d.o.f.) before being mechanically stabilized to the nm scale above 1 Hz. This contribution describes the approach of performing this active pre-alignment based on an eccentric cam system. In order to limit the amplification of the vibration sources at resonant frequencies a sufficiently high Eigenfrequency is required. Therefore the contact region between cam and support was optimized for adequate stiffness based on the Hertzian theory. Furthermore, practical tests performed on a single degree of freedom mock-up wil...

Influence of pre-harvest red light irradiation on main phytochemicals and antioxidant activity of Chinese kale sprouts.

Science.gov (United States)

Deng, Mingdan; Qian, Hongmei; Chen, Lili; Sun, Bo; Chang, Jiaqi; Miao, Huiying; Cai, Congxi; Wang, Qiaomei

2017-05-01

The effects of pre-harvest red light irradiation on main healthy phytochemicals as well as antioxidant activity of Chinese kale sprouts during postharvest storage were investigated. 6-day-old sprouts were treated by red light for 24h before harvest and sampled for further analysis of nutritional quality on the first, second and third day after harvest. The results indicated that red light exposure notably postponed the degradation of aliphatic, indole, and total glucosinolates during postharvest storage. The vitamin C level was remarkably higher in red light treated sprouts on the first and second day after harvest when compared with the control. In addition, red light treatment also enhanced the accumulation of total phenolics and maintained higher level of antioxidant activity than the control. All above results suggested that pre-harvest red light treatment might provide a new strategy to maintain the nutritive value of Chinese kale sprouts during postharvest storage. Copyright © 2016 Elsevier Ltd. All rights reserved.

VizieR Online Data Catalog: Bidelman-Parsons Spectroscopic/Bibliographic Cat (Parsons+ 1980)

Science.gov (United States)

Parsons, S. B.; Buta, N. S.; Bidelman, W. P.

1996-11-01

The Bidelman-Parsons Spectroscopic and Bibliographical Catalog (BPSB; Parsons, Buta, and Bidelman 1980a, b) contains data compiled from the astronomical literature by W. P. Bidelman. These data include diverse catalogs and lists, especially from pre-1950 journals (minor as well as major), and from pre-1962 observatory publications. From more recent years, the data on any object frequently are limited to one item with a reference; for example, a spectral type. No data published after 1973 are included. Over 200 publications are represented. The BPSB has information on 40,312 objects. The catalog contains most of the same information on MK spectral types as the Catalogue of Stellar Spectra Classified in the Morgan-Keenan System (Jaschek, Conde, and de Sierra 1964) and its updates, but it also includes such items as spectral types without a luminosity class (certainly better than nothing); spectroscopic absolute magnitudes; notes on multiplicity; notes on high proper motion or radial velocity (with the values, if probably variable, or if greater than 60 km/s); unpublished remarks and spectral types from several sources, including Bidelman and Henize; and Bidelman's preliminary identifications of many sources in the Two-Micron Sky Survey (Neugebauer and Leighton 1969). Some of the longer lists included in the catalog are those of OB stars from the Tonantzintla-Tacubaya and Heidelberg-Koenigstuhl surveys (Iriarte and Chavira 1957; Chavira 1958; Klare and Szeidl 1966); that of OB stars with emission from the Case-Hamburg surveys (Hardorp et al. 1959; Stock, Nassau, and Stephenson 1960; Hardorp, Theile, and Voigt 1964; Nassau and Stephenson 1963; Hardorp, Theile, and Voigt 1965; Nassau, Stephenson, and MacConnell 1965; Stephenson and Sanduleak 1971); and stars from the General Catalogue of Variable Stars (Kukarkin et al. 1969); and the Catalogue of Suspected Variable Stars (Kukarkin et al. 1951, 1965). Although the catalog is mainly of stellar data, it includes many

Pre-crastination in the pigeon.

Science.gov (United States)

Wasserman, Edward A; Brzykcy, Stephen J

2015-08-01

Procrastination is the tendency to delay initiating or completing tasks. Rosenbaum et al. (Psychological Science, May 8, 2014) recently documented the opposite of procrastination: pre-crastination, the tendency to begin or to finish tasks as soon as possible. We devised a simple two-alternative forced-choice task, in which pigeons could choose to switch response location either sooner or later in a sequence of actions eventuating in food reward. Even though there was no economic advantage for doing so, pigeons chose to switch response location sooner rather than later in the sequence, showing pre-crastination to be quite general. Pre-crastination thus joins other anticipatory learning phenomena in challenging rational or optimal accounts of behavioral adaptation.

Proton magnetic resonance spectroscopic imaging in neurodegenerative diseases

International Nuclear Information System (INIS)

Schuff, Norbert; Vermathen, Peter; Maudsley, Andrew A.; Weiner, Michael W.

1999-01-01

Proton magnetic resonance spectroscopic imaging ( 1 H MRSI) was used to investigate changes in brain metabolites in Alzheimer's disease, epilepsy, and amyotrophic lateral sclerosis. Examples of results from several ongoing clinical studies are provided. Multislice 1 H MRSI of the human brain, without volume pre selection offers considerable advantage over previously available techniques. Furthermore, MRI tissue segmentation and completely automated spectral curve fitting greatly facilitate quantitative data analysis. Future efforts will be devoted to obtain full volumetric brain coverage and data acquisition at short spin-echo times (TE<30 ms) for the detection of metabolites. (author)

Spectroscopic Tools for Quantitative Studies of DNA Structure and Dynamics

DEFF Research Database (Denmark)

Preus, Søren

The main objective of this thesis is to develop quantitative fluorescence-based, spectroscopic tools for probing the 3D structure and dynamics of DNA and RNA. The thesis is founded on six peer-reviewed papers covering mainly the development, characterization and use of fluorescent nucleobase...... analogues. In addition, four software packages is presented for the simulation and quantitative analysis of time-resolved and steady-state UV-Vis absorption and fluorescence experiments....

Genome Sequencing

DEFF Research Database (Denmark)

Sato, Shusei; Andersen, Stig Uggerhøj

2014-01-01

The current Lotus japonicus reference genome sequence is based on a hybrid assembly of Sanger TAC/BAC, Sanger shotgun and Illumina shotgun sequencing data generated from the Miyakojima-MG20 accession. It covers nearly all expressed L. japonicus genes and has been annotated mainly based on transcr......The current Lotus japonicus reference genome sequence is based on a hybrid assembly of Sanger TAC/BAC, Sanger shotgun and Illumina shotgun sequencing data generated from the Miyakojima-MG20 accession. It covers nearly all expressed L. japonicus genes and has been annotated mainly based...

LINEAR RELATION FOR WIND-BLOWN BUBBLE SIZES OF MAIN-SEQUENCE OB STARS IN A MOLECULAR ENVIRONMENT AND IMPLICATION FOR SUPERNOVA PROGENITORS

Energy Technology Data Exchange (ETDEWEB)

Chen Yang; Zhou Ping [Department of Astronomy, Nanjing University, Nanjing 210093 (China); Chu Youhua [Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States)

2013-05-20

We find a linear relationship between the size of a massive star's main-sequence bubble in a molecular environment and the star's initial mass: R{sub b} Almost-Equal-To 1.22 M/M{sub Sun} - 9.16 pc, assuming a constant interclump pressure. Since stars in the mass range of 8 to 25-30 M{sub Sun} will end their evolution in the red supergiant phase without launching a Wolf-Rayet wind, the main-sequence wind-blown bubbles are mainly responsible for the extent of molecular gas cavities, while the effect of the photoionization is comparatively small. This linear relation can thus be used to infer the masses of the massive star progenitors of supernova remnants (SNRs) that are discovered to evolve in molecular cavities, while few other means are available for inferring the properties of SNR progenitors. We have used this method to estimate the initial masses of the progenitors of eight SNRs: Kes 69, Kes 75, Kes 78, 3C 396, 3C 397, HC 40, Vela, and RX J1713-3946.

Reconstruction of the pre-compactional thickness of the Zechstein Main Dolomite in northwest Poland

Directory of Open Access Journals (Sweden)

Semyrka Grażyna

2015-12-01

Full Text Available Our reconstruction of the pre-compactional thickness of the Main Dolomite strata from the so-called Grotów Peninsula (northwest Poland was based on macroscopic observations of drill cores from three wells: Mokrzec-1, Sieraków-4 and Międzychód-5. These wells are located in various palaeogeographical zones of the Main Dolomite and cored rocks represent a range of microfacies. The amount of compactional reduction in thickness of the Main Dolomite was estimated by summing the total heights (Wst of all stylolites encountered in logs of these wells. For calculations, a generalised model of a drill core was developed, which embraced all types of stylolite seams present in the Main Dolomite succession studied. Also the method of stylolite dimensioning was demonstrated. The number of stylolites in the drill cores studied varied from 511 in the Sieraków-4 well to 1,534 in the Międzychód-5 well. In all cores studied low-amplitude macrostylolites predominated, but the reduction of thickness was controlled mostly by the low- and medium-amplitude macrostylolites. The largest number of stylolites was found in the grainstone/packstone microfacies. The turnout of stylolites depends of microfacies. The highest density of stylolites was documented in mudstones/wackestones (24 stylolites per metre of rock thickness and the lowest in boundstones (14 stylolites per metre of rock thickness. The low-amplitude stylolites appear most frequently in the mudstone/wackestone microfacies (15 stylolites per metre of rock thickness; in grainstones/packstones, rudstones/floatstones and boundstones middle-amplitude stylolites are rare (3 stylolites per metre of rock thickness. The degree of compaction of the Main Dolomite succession studied varied from 6 to 10%; hence, its calculated initial thickness also varied in the wells studied: from 41.3 m in the Sieraków-4 well to 56.9 m in the Mokrzec-1 well and to 97.1 m in the Międzychód-5 well. The volumes of reservoir

A HIGHER EFFICIENCY OF CONVERTING GAS TO STARS PUSHES GALAXIES AT z ∼ 1.6 WELL ABOVE THE STAR-FORMING MAIN SEQUENCE

Energy Technology Data Exchange (ETDEWEB)

Silverman, J. D.; Rujopakarn, W. [Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Daddi, E.; Liu, D. [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, Irfu/Service d’Astrophysique, CEA Saclay (France); Rodighiero, G. [Dipartimento di Fisica e Astronomia, Universita di Padova, vicolo Osservatorio, 3, I-35122 Padova (Italy); Sargent, M. [Astronomy Centre, Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH (United Kingdom); Renzini, A. [Instituto Nazionale de Astrofisica, Osservatorio Astronomico di Padova, v.co dell’Osservatorio 5, I-35122 Padova (Italy); Feruglio, C. [IRAM—Institut de RadioAstronomie Millimétrique, 300 rue de la Piscine, F-38406 Saint Martin d’Hères (France); Kashino, D. [Division of Particle and Astrophysical Science, Graduate School of Science, Nagoya University, Nagoya 464-8602 (Japan); Sanders, D. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Kartaltepe, J. [National Optical Astronomy Observatory, 950 N. Cherry Avenue, Tucson, AZ 85719 (United States); Nagao, T. [Graduate School of Science and Engineering, Ehime University, 2-5 Bunkyo-cho, Matsuyama 790-8577 (Japan); Arimoto, N. [Subaru Telescope, 650 North A’ohoku Place, Hilo, HI-96720 (United States); Berta, S.; Lutz, D. [Max-Planck-Institut für extraterrestrische Physik, D-84571 Garching (Germany); Béthermin, M. [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching (Germany); Koekemoer, A., E-mail: john.silverman@ipmu.jp [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD, 21218 (United States); and others

2015-10-20

Local starbursts have a higher efficiency of converting gas into stars, as compared to typical star-forming galaxies at a given stellar mass, possibly indicative of different modes of star formation. With the peak epoch of galaxy formation occurring at z > 1, it remains to be established whether such an efficient mode of star formation is occurring at high redshift. To address this issue, we measure the molecular gas content of seven high-redshift (z ∼ 1.6) starburst galaxies with the Atacama Large Millimeter/submillimeter Array and IRAM/Plateau de Bure Interferometer. Our targets are selected from the sample of Herschel far-infrared-detected galaxies having star formation rates (∼300–800 M{sub ⊙} yr{sup −1}) elevated (≳4×) above the star-forming main sequence (MS) and included in the FMOS-COSMOS near-infrared spectroscopic survey of star-forming galaxies at z ∼ 1.6 with Subaru. We detect CO emission in all cases at high levels of significance, indicative of high gas fractions (∼30%–50%). Even more compelling, we firmly establish with a clean and systematic selection that starbursts, identified as MS outliers, at high redshift generally have a lower ratio of CO to total infrared luminosity as compared to typical MS star-forming galaxies, although with a smaller offset than expected based on past studies of local starbursts. We put forward a hypothesis that there exists a continuous increase in star formation efficiency with elevation from the MS with galaxy mergers as a possible physical driver. Along with a heightened star formation efficiency, our high-redshift sample is similar in other respects to local starbursts, such as being metal rich and having a higher ionization state of the interstellar medium.

Design and control of integrated chromatography column sequences.

Science.gov (United States)

Andersson, Niklas; Löfgren, Anton; Olofsson, Marianne; Sellberg, Anton; Nilsson, Bernt; Tiainen, Peter

2017-07-01

To increase the productivity in biopharmaceutical production, a natural step is to introduce integrated continuous biomanufacturing which leads to fewer buffer and storage tanks, smaller sizes of integrated unit operations, and full automation of the operation. The main contribution of this work is to illustrate a methodology for design and control of a downstream process based on integrated column sequences. For small scale production, for example, pre-clinical studies, integrated column sequences can be implemented on a single chromatography system. This makes for a very efficient drug development platform. The proposed methodology is composed of four steps and is governed by a set of tools, that is presented, that makes the transition from batch separations to a complete integrated separation sequence as easy as possible. This methodology, its associated tools and the physical implementation is presented and illustrated on a case study where the target protein is separated from impurities through an integrated four column sequence. This article shows that the design and control of an integrated column sequence was successfully implemented for a tertiary protein separation problem. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:923-930, 2017. © 2017 American Institute of Chemical Engineers.

HII 2407: AN ECLIPSING BINARY REVEALED BY K2 OBSERVATIONS OF THE PLEIADES

Energy Technology Data Exchange (ETDEWEB)

David, Trevor J.; Hillenbrand, Lynne A.; Zhang, Celia; Riddle, Reed L. [Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Stauffer, John; Rebull, L. M. [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Cody, Ann Marie [NASA Ames Research Center, Mountain View, CA 94035 (United States); Conroy, Kyle; Stassun, Keivan G. [Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States); Pope, Benjamin; Aigrain, Suzanne; Gillen, Ed [Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Cameron, Andrew Collier [SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS (United Kingdom); Barrado, David [Centro de Astrobiología, INTA-CSIC, Dpto. Astrofísica, ESAC Campus, P.O. Box 78, E-28691 Villanueva de la Cañada, Madrid (Spain); Isaacson, Howard; Marcy, Geoffrey W. [Department of Astronomy, University of California, Berkeley, CA 94720 (United States); Ziegler, Carl; Law, Nicholas M. [Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3255 (United States); Baranec, Christoph, E-mail: tjd@astro.caltech.edu [Institute for Astronomy, University of Hawai‘i at Mānoa, Hilo, HI 96720-2700 (United States)

2015-11-20

The star HII 2407 is a member of the relatively young Pleiades star cluster and was previously discovered to be a single-lined spectroscopic binary. It is newly identified here within Kepler/K2 photometric time series data as an eclipsing binary system. Mutual fitting of the radial velocity and photometric data leads to an orbital solution and constraints on fundamental stellar parameters. While the primary has arrived on the main sequence, the secondary is still pre-main sequence and we compare our results for the M/M{sub ⊙} and R/R{sub ⊙} values with stellar evolutionary models. We also demonstrate that the system is likely to be tidally synchronized. Follow-up infrared spectroscopy is likely to reveal the lines of the secondary, allowing for dynamically measured masses and elevating the system to benchmark eclipsing binary status.

THE TIME DOMAIN SPECTROSCOPIC SURVEY: VARIABLE SELECTION AND ANTICIPATED RESULTS

Energy Technology Data Exchange (ETDEWEB)

Morganson, Eric; Green, Paul J. [Harvard Smithsonian Center for Astrophysics, 60 Garden St, Cambridge, MA 02138 (United States); Anderson, Scott F.; Ruan, John J. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Myers, Adam D. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Eracleous, Michael; Brandt, William Nielsen [Department of Astronomy and Astrophysics, 525 Davey Laboratory, The Pennsylvania State University, University Park, PA 16802 (United States); Kelly, Brandon [Department of Physics, Broida Hall, University of California, Santa Barbara, CA 93106-9530 (United States); Badenes, Carlos [Department of Physics and Astronomy and Pittsburgh Particle Physics, Astrophysics and Cosmology Center (PITT PACC), University of Pittsburgh, 3941 O’Hara St, Pittsburgh, PA 15260 (United States); Bañados, Eduardo [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Blanton, Michael R. [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Bershady, Matthew A. [Department of Astronomy, University of Wisconsin, 475 N. Charter St., Madison, WI 53706 (United States); Borissova, Jura [Instituto de Física y Astronomía, Universidad de Valparaíso, Av. Gran Bretaña 1111, Playa Ancha, Casilla 5030, and Millennium Institute of Astrophysics (MAS), Santiago (Chile); Burgett, William S. [GMTO Corp, Suite 300, 251 S. Lake Ave, Pasadena, CA 91101 (United States); Chambers, Kenneth, E-mail: emorganson@cfa.harvard.edu [Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States); and others

2015-06-20

We present the selection algorithm and anticipated results for the Time Domain Spectroscopic Survey (TDSS). TDSS is an Sloan Digital Sky Survey (SDSS)-IV Extended Baryon Oscillation Spectroscopic Survey (eBOSS) subproject that will provide initial identification spectra of approximately 220,000 luminosity-variable objects (variable stars and active galactic nuclei across 7500 deg{sup 2} selected from a combination of SDSS and multi-epoch Pan-STARRS1 photometry. TDSS will be the largest spectroscopic survey to explicitly target variable objects, avoiding pre-selection on the basis of colors or detailed modeling of specific variability characteristics. Kernel Density Estimate analysis of our target population performed on SDSS Stripe 82 data suggests our target sample will be 95% pure (meaning 95% of objects we select have genuine luminosity variability of a few magnitudes or more). Our final spectroscopic sample will contain roughly 135,000 quasars and 85,000 stellar variables, approximately 4000 of which will be RR Lyrae stars which may be used as outer Milky Way probes. The variability-selected quasar population has a smoother redshift distribution than a color-selected sample, and variability measurements similar to those we develop here may be used to make more uniform quasar samples in large surveys. The stellar variable targets are distributed fairly uniformly across color space, indicating that TDSS will obtain spectra for a wide variety of stellar variables including pulsating variables, stars with significant chromospheric activity, cataclysmic variables, and eclipsing binaries. TDSS will serve as a pathfinder mission to identify and characterize the multitude of variable objects that will be detected photometrically in even larger variability surveys such as Large Synoptic Survey Telescope.

Gradient waveform pre-emphasis based on the gradient system transfer function.

Science.gov (United States)

Stich, Manuel; Wech, Tobias; Slawig, Anne; Ringler, Ralf; Dewdney, Andrew; Greiser, Andreas; Ruyters, Gudrun; Bley, Thorsten A; Köstler, Herbert

2018-02-25

The gradient system transfer function (GSTF) has been used to describe the distorted k-space trajectory for image reconstruction. The purpose of this work was to use the GSTF to determine the pre-emphasis for an undistorted gradient output and intended k-space trajectory. The GSTF of the MR system was determined using only standard MR hardware without special equipment such as field probes or a field camera. The GSTF was used for trajectory prediction in image reconstruction and for a gradient waveform pre-emphasis. As test sequences, a gradient-echo sequence with phase-encoding gradient modulation and a gradient-echo sequence with a spiral read-out trajectory were implemented and subsequently applied on a structural phantom and in vivo head measurements. Image artifacts were successfully suppressed by applying the GSTF-based pre-emphasis. Equivalent results are achieved with images acquired using GSTF-based post-correction of the trajectory as a part of image reconstruction. In contrast, the pre-emphasis approach allows reconstruction using the initially intended trajectory. The artifact suppression shown for two sequences demonstrates that the GSTF can serve for a novel pre-emphasis. A pre-emphasis based on the GSTF information can be applied to any arbitrary sequence type. © 2018 International Society for Magnetic Resonance in Medicine.

Spectroscopic Parameters of Lumbar Intervertebral Disc Material

Science.gov (United States)

Terbetas, G.; Kozlovskaja, A.; Varanius, D.; Graziene, V.; Vaitkus, J.; Vaitkuviene, A.

2009-06-01

There are numerous methods of investigating intervertebral disc. Visualization methods are widely used in clinical practice. Histological, imunohistochemical and biochemical methods are more used in scientific research. We propose that a new spectroscopic investigation would be useful in determining intervertebral disc material, especially when no histological specimens are available. Purpose: to determine spectroscopic parameters of intervertebral disc material; to determine emission spectra common for all intervertebral discs; to create a background for further spectroscopic investigation where no histological specimen will be available. Material and Methods: 20 patients, 68 frozen sections of 20 μm thickness from operatively removed intervertebral disc hernia were excited by Nd:YAG microlaser STA-01-TH third harmonic 355 nm light throw 0, 1 mm fiber. Spectrophotometer OceanOptics USB2000 was used for spectra collection. Mathematical analysis of spectra was performed by ORIGIN multiple Gaussian peaks analysis. Results: In each specimen of disc hernia were found distinct maximal spectral peaks of 4 types supporting the histological evaluation of mixture content of the hernia. Fluorescence in the spectral regions 370-700 nm was detected in the disc hernias. The main spectral component was at 494 nm and the contribution of the components with the peak wavelength values at 388 nm, 412 nm and 435±5 nm were varying in the different groups of samples. In comparison to average spectrum of all cases, there are 4 groups of different spectral signatures in the region 400-500 nm in the patient groups, supporting a clinical data on different clinical features of the patients. Discussion and Conclusion: besides the classical open discectomy, new minimally invasive techniques of treating intervertebral disc emerge (PLDD). Intervertebral disc in these techniques is assessed by needle, no histological specimen is taken. Spectroscopic investigation via fiber optics through the

THE DISCOVERY OF SOLAR-LIKE ACTIVITY CYCLES BEYOND THE END OF THE MAIN SEQUENCE?

Energy Technology Data Exchange (ETDEWEB)

Route, Matthew, E-mail: mroute@purdue.edu [Research Computing, Information Technology at Purdue, Purdue University, 155 S. Grant Street, West Lafayette, IN 47907 (United States)

2016-10-20

The long-term magnetic behavior of objects near the cooler end of the stellar main sequence is poorly understood. Most theoretical work on the generation of magnetism in these ultracool dwarfs (spectral type ≥M7 stars and brown dwarfs) suggests that their magnetic fields should not change in strength and direction. Using polarized radio emission measurements of their magnetic field orientations, I demonstrate that these cool, low-mass, fully convective objects appear to undergo magnetic polarity reversals analogous to those that occur on the Sun. This powerful new technique potentially indicates that the patterns of magnetic activity displayed by the Sun continue to exist, despite the fully convective interiors of these objects, in contravention of several leading theories of the generation of magnetic fields by internal dynamos.

Stellar Variability at the Main-sequence Turnoff of the Intermediate-age LMC Cluster NGC 1846

Science.gov (United States)

Salinas, R.; Pajkos, M. A.; Vivas, A. K.; Strader, J.; Contreras Ramos, R.

2018-04-01

Intermediate-age (IA) star clusters in the Large Magellanic Cloud (LMC) present extended main-sequence turn-offs (MSTO) that have been attributed to either multiple stellar populations or an effect of stellar rotation. Recently it has been proposed that these extended main sequences can also be produced by ill-characterized stellar variability. Here we present Gemini-S/Gemini Multi-Object Spectrometer (GMOS) time series observations of the IA cluster NGC 1846. Using differential image analysis, we identified 73 new variable stars, with 55 of those being of the Delta Scuti type, that is, pulsating variables close the MSTO for the cluster age. Considering completeness and background contamination effects, we estimate the number of δ Sct belonging to the cluster between 40 and 60 members, although this number is based on the detection of a single δ Sct within the cluster half-light radius. This amount of variable stars at the MSTO level will not produce significant broadening of the MSTO, albeit higher-resolution imaging will be needed to rule out variable stars as a major contributor to the extended MSTO phenomenon. Though modest, this amount of δ Sct makes NGC 1846 the star cluster with the highest number of these variables ever discovered. Lastly, our results present a cautionary tale about the adequacy of shallow variability surveys in the LMC (like OGLE) to derive properties of its δ Sct population. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), and Ministério da Ciência, Tecnologia e Inovação (Brazil).

STELLAR DIAMETERS AND TEMPERATURES. II. MAIN-SEQUENCE K- AND M-STARS

Energy Technology Data Exchange (ETDEWEB)

Boyajian, Tabetha S.; McAlister, Harold A.; Jones, Jeremy; White, Russel; Henry, Todd; Gies, Douglas; Jao, Wei-Chun; Parks, J. Robert [Center for High Angular Resolution Astronomy and Department of Physics and Astronomy, Georgia State University, P.O. Box 4106, Atlanta, GA 30302-4106 (United States); Von Braun, Kaspar; Kane, Stephen R.; Ciardi, David [NASA Exoplanet Science Institute, California Institute of Technology, MC 100-22, Pasadena, CA 91125 (United States); Van Belle, Gerard [Lowell Observatory, Flagstaff, AZ 86001 (United States); Ten Brummelaar, Theo A.; Schaefer, Gail; Sturmann, Laszlo; Sturmann, Judit [The CHARA Array, Mount Wilson Observatory, Mount Wilson, CA 91023 (United States); Muirhead, Philip S. [Department of Astronomy, California Institute of Technology, 1200 East California Boulevard, MC 249-17, Pasadena, CA 91125 (United States); Lopez-Morales, Mercedes [Institut de Ciencies de L' Espai (CSIC-IEEC), E-08193 Bellaterra (Spain); Ridgway, Stephen [National Optical Astronomy Observatory, P.O. Box 26732, Tucson, AZ 85726-6732 (United States); Rojas-Ayala, Barbara [Department of Astrophysics, Division of Physical Sciences, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024 (United States); and others

2012-10-01

We present interferometric angular diameter measurements of 21 low-mass, K- and M-dwarfs made with the CHARA Array. This sample is enhanced by adding a collection of radius measurements published in the literature to form a total data set of 33 K-M-dwarfs with diameters measured to better than 5%. We use these data in combination with the Hipparcos parallax and new measurements of the star's bolometric flux to compute absolute luminosities, linear radii, and effective temperatures for the stars. We develop empirical relations for {approx}K0 to M4 main-sequence stars that link the stellar temperature, radius, and luminosity to the observed (B - V), (V - R), (V - I), (V - J), (V - H), and (V - K) broadband color index and stellar metallicity [Fe/H]. These relations are valid for metallicities ranging from [Fe/H] = -0.5 to +0.1 dex and are accurate to {approx}2%, {approx}5%, and {approx}4% for temperature, radius, and luminosity, respectively. Our results show that it is necessary to use metallicity-dependent transformations in order to properly convert colors into stellar temperatures, radii, and luminosities. Alternatively, we find no sensitivity to metallicity on relations we construct to the global properties of a star omitting color information, e.g., temperature-radius and temperature-luminosity. Thus, we are able to empirically quantify to what order the star's observed color index is impacted by the stellar iron abundance. In addition to the empirical relations, we also provide a representative look-up table via stellar spectral classifications using this collection of data. Robust examinations of single star temperatures and radii compared to evolutionary model predictions on the luminosity-temperature and luminosity-radius planes reveal that models overestimate the temperatures of stars with surface temperatures <5000 K by {approx}3%, and underestimate the radii of stars with radii <0.7 R{sub Sun} by {approx}5%. These conclusions additionally

A Population Study of Wide-Separation Brown Dwarf Companions to Main Sequence Stars

Science.gov (United States)

Smith, Jeffrey J.

2005-01-01

Increased interest in infrared astronomy has opened the frontier to study cooler objects that shed significant light on the formation of planetary systems. Brown dwarf research provides a wealth of information useful for sorting through a myriad of proposed formation theories. Our study combines observational data from 2MASS with rigorous computer simulations to estimate the true population of long-range (greater than 1000 AU) brown dwarf companions in the solar neighborhood (less than 25 pc from Earth). Expanding on Gizis et al. (2001), we have found the margin of error in previous estimates to be significantly underestimated after we included orbit eccentricity, longitude of pericenter, angle of inclination, field star density, and primary and secondary luminosities as parameters influencing the companion systems in observational studies. We apply our simulation results to current L- and T-dwarf catalogs to provide updated estimates on the frequency of wide-separation brown dwarf companions to main sequence stars.

Shell model and spectroscopic factors

International Nuclear Information System (INIS)

Poves, P.

2007-01-01

In these lectures, I introduce the notion of spectroscopic factor in the shell model context. A brief review is given of the present status of the large scale applications of the Interacting Shell Model. The spectroscopic factors and the spectroscopic strength are discussed for nuclei in the vicinity of magic closures and for deformed nuclei. (author)

Characterization of intronic uridine-rich sequence elements acting as possible targets for nuclear proteins during pre-mRNA splicing in Nicotiana plumbaginifolia.

Science.gov (United States)

Gniadkowski, M; Hemmings-Mieszczak, M; Klahre, U; Liu, H X; Filipowicz, W

1996-02-15

Introns of nuclear pre-mRNAs in dicotyledonous plants, unlike introns in vertebrates or yeast, are distinctly rich in A+U nucleotides and this feature is essential for their processing. In order to define more precisely sequence elements important for intron recognition in plants, we investigated the effects of short insertions, either U-rich or A-rich, on splicing of synthetic introns in transfected protoplast of Nicotiana plumbaginifolia. It was found that insertions of U-rich (sequence UUUUUAU) but not A-rich (AUAAAAA) segments can activate splicing of a GC-rich synthetic infron, and that U-rich segments, or multimers thereof, can function irrespective of the site of insertion within the intron. Insertions of multiple U-rich segments, either at the same or different locations, generally had an additive, stimulatory effect on splicing. Mutational analysis showed that replacement of one or two U residues in the UUUUUAU sequence with A or C residues had only a small effect on splicing, but replacement with G residues was strongly inhibitory. Proteins that interact with fragments of natural and synthetic pre-mRNAs in vitro were identified in nuclear extracts of N.plumbaginifolia by UV cross- linking. The profile of cross-linked plant proteins was considerably less complex than that obtained with a HeLa cell nuclear extract. Two major cross-linkable plant proteins had apparent molecular mass of 50 and 54 kDa and showed affinity for oligouridilates present in synGC introns or for poly(U).

Analysis of fundamental parameters for V477 Lyr

Science.gov (United States)

Shimansky, V. V.; Pozdnyakova, S. A.; Borisov, N. V.; Bikmaev, I. F.; Galeev, A. I.; Sakhibullin, N. A.; Spiridonova, O. I.

2008-06-01

We analyze the photometric and spectroscopic observations of the young pre-cataclysmic variable (pre-CV) V477 Lyr. The masses of both binary components have been corrected by analyzing their radial velocity curves. We show that agreement between the theoretical and observed light curves of the object is possible for several sets of its physical parameters corresponding to the chosen temperature of the primary component. The final parameters of V477 Lyr have been established by comparing observational data with evolutionary tracks for planetary nebula nuclei. The derived effective temperature of the O subdwarf is higher than that estimated by analyzing the object’s ultraviolet spectra by more than 10000 K. This is in agreement with the analogous results obtained previously for the young pre-CVs V664 Cas and UU Sge. The secondary component of V477 Lyr has been proven to have a more than 25-fold luminosity excess compared to main-sequence stars of similar mass. Comparison of the physical parameters for the cool stars in young pre-CVs indicates that their luminosities do not correlate with the masses of the objects. The observed luminosity excesses in such stars show a close correlation with the post-common-envelope lifetime of the systems and should be investigated within the framework of the theory of their relaxation to the state of main-sequence stars.

The age-metallicity relation in the solar neighbourhood from a pilot sample of white dwarf-main sequence binaries

OpenAIRE

Rebassa-Mansergas, A.; Anguiano, B.; García-Berro, E.; Freeman, K. C.; Cojocaru, R.; Manser, C. J.; Pala, A. F.; Gänsicke, B. T.; Liu, X. -W.

2016-01-01

The age–metallicity relation (AMR) is a fundamental observational constraint for understanding how the Galactic disc formed and evolved chemically in time. However, there is not yet an agreement on the observational properties of the AMR for the solar neighbourhood, primarily due to the difficulty in obtaining accurate stellar ages for individual field stars. We have started an observational campaign for providing the much needed observational input by using wide white-dwarf–main-sequence (WD...

HABITABLE ZONES AROUND MAIN-SEQUENCE STARS: DEPENDENCE ON PLANETARY MASS

International Nuclear Information System (INIS)

Kopparapu, Ravi Kumar; Ramirez, Ramses M.; Kasting, James F.; SchottelKotte, James; Domagal-Goldman, Shawn; Eymet, Vincent

2014-01-01

The ongoing discoveries of extra-solar planets are unveiling a wide range of terrestrial mass (size) planets around their host stars. In this Letter, we present estimates of habitable zones (HZs) around stars with stellar effective temperatures in the range 2600 K-7200 K, for planetary masses between 0.1 M ⊕ and 5 M ⊕ . Assuming H 2 O-(inner HZ) and CO 2 -(outer HZ) dominated atmospheres, and scaling the background N 2 atmospheric pressure with the radius of the planet, our results indicate that larger planets have wider HZs than do smaller ones. Specifically, with the assumption that smaller planets will have less dense atmospheres, the inner edge of the HZ (runaway greenhouse limit) moves outward (∼10% lower than Earth flux) for low mass planets due to larger greenhouse effect arising from the increased H 2 O column depth. For larger planets, the H 2 O column depth is smaller, and higher temperatures are needed before water vapor completely dominates the outgoing longwave radiation. Hence the inner edge moves inward (∼7% higher than Earth's flux). The outer HZ changes little due to the competing effects of the greenhouse effect and an increase in albedo. New, three-dimensional climate model results from other groups are also summarized, and we argue that further, independent studies are needed to verify their predictions. Combined with our previous work, the results presented here provide refined estimates of HZs around main-sequence stars and provide a step toward a more comprehensive analysis of HZs

Habitable Zones Around Main-Sequence Stars: Dependence on Planetary Mass

Science.gov (United States)

Kopparapu, Ravi Kumar; Ramirez, Ramses M.; Kotte, James Schottel; Kasting, James F.; Domagal-Goldman, Shawn; Eymet, Vincent

2014-01-01

The ongoing discoveries of extra-solar planets are unveiling a wide range of terrestrial mass (size) planets around their host stars. In this Letter, we present estimates of habitable zones (HZs) around stars with stellar effective temperatures in the range 2600 K-7200 K, for planetary masses between 0.1M and 5M. Assuming H2O-(inner HZ) and CO2-(outer HZ) dominated atmospheres, and scaling the background N2 atmospheric pressure with the radius of the planet, our results indicate that larger planets have wider HZs than do smaller ones. Specifically, with the assumption that smaller planets will have less dense atmospheres, the inner edge of the HZ (runaway greenhouse limit) moves outward (approx.10% lower than Earth flux) for low mass planets due to larger greenhouse effect arising from the increased H2O column depth. For larger planets, the H2O column depth is smaller, and higher temperatures are needed before water vapor completely dominates the outgoing long-wave radiation. Hence the inner edge moves inward (approx.7% higher than Earth's flux). The outer HZ changes little due to the competing effects of the greenhouse effect and an increase in albedo. New, three-dimensional climate model results from other groups are also summarized, and we argue that further, independent studies are needed to verify their predictions. Combined with our previous work, the results presented here provide refined estimates of HZs around main-sequence stars and provide a step toward a more comprehensive analysis of HZs.

HABITABLE ZONES AROUND MAIN-SEQUENCE STARS: DEPENDENCE ON PLANETARY MASS

Energy Technology Data Exchange (ETDEWEB)

Kopparapu, Ravi Kumar; Ramirez, Ramses M.; Kasting, James F. [Department of Geosciences, Penn State University, 443 Deike Building, University Park, PA 16802 (United States); SchottelKotte, James [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Domagal-Goldman, Shawn [NASA Astrobiology Institute' s Virtual Planetary Laboratory, P.O. Box 351580, Seattle, WA 98195 (United States); Eymet, Vincent, E-mail: ruk15@psu.edu [Laboratoire d' Astrophysique de Bordeaux, Universite de Bordeaux 1, UMR 5804, F-33270 Floirac (France)

2014-06-01

The ongoing discoveries of extra-solar planets are unveiling a wide range of terrestrial mass (size) planets around their host stars. In this Letter, we present estimates of habitable zones (HZs) around stars with stellar effective temperatures in the range 2600 K-7200 K, for planetary masses between 0.1 M {sub ⊕} and 5 M {sub ⊕}. Assuming H{sub 2}O-(inner HZ) and CO{sub 2}-(outer HZ) dominated atmospheres, and scaling the background N{sub 2} atmospheric pressure with the radius of the planet, our results indicate that larger planets have wider HZs than do smaller ones. Specifically, with the assumption that smaller planets will have less dense atmospheres, the inner edge of the HZ (runaway greenhouse limit) moves outward (∼10% lower than Earth flux) for low mass planets due to larger greenhouse effect arising from the increased H{sub 2}O column depth. For larger planets, the H{sub 2}O column depth is smaller, and higher temperatures are needed before water vapor completely dominates the outgoing longwave radiation. Hence the inner edge moves inward (∼7% higher than Earth's flux). The outer HZ changes little due to the competing effects of the greenhouse effect and an increase in albedo. New, three-dimensional climate model results from other groups are also summarized, and we argue that further, independent studies are needed to verify their predictions. Combined with our previous work, the results presented here provide refined estimates of HZs around main-sequence stars and provide a step toward a more comprehensive analysis of HZs.

POST-MAIN SEQUENCE EVOLUTION OF ICY MINOR PLANETS: IMPLICATIONS FOR WATER RETENTION AND WHITE DWARF POLLUTION

Energy Technology Data Exchange (ETDEWEB)

Malamud, Uri; Perets, Hagai B., E-mail: uri.mal@tx.technion.ac.il, E-mail: hperets@physics.technion.ac.il [Department of Physics, Technion (Israel)

2016-12-01

Most observations of polluted white dwarf atmospheres are consistent with accretion of water-depleted planetary material. Among tens of known cases, merely two involve accretion of objects that contain a considerable mass fraction of water. The purpose of this study is to investigate the relative scarcity of these detections. Based on a new and highly detailed model, we evaluate the retention of water inside icy minor planets during the high-luminosity stellar evolution that follows the main sequence. Our model fully considers the thermal, physical, and chemical evolution of icy bodies, following their internal differentiation as well as water depletion, from the moment of their birth and through all stellar evolution phases preceding the formation of the white dwarf. We also account for different initial compositions and formation times. Our results differ from previous studies, which have either underestimated or overestimated water retention. We show that water can survive in a variety of circumstances and in great quantities, and therefore other possibilities are discussed in order to explain the infrequency of water detection. We predict that the sequence of accretion is such that water accretes earlier, and more rapidly, than the rest of the silicate disk, considerably reducing the chance of its detection in H-dominated atmospheres. In He-dominated atmospheres, the scarcity of water detections could be observationally biased. It implies that the accreted material is typically intrinsically dry, which may be the result of the inside-out depopulation sequence of minor planets.

POST-MAIN SEQUENCE EVOLUTION OF ICY MINOR PLANETS: IMPLICATIONS FOR WATER RETENTION AND WHITE DWARF POLLUTION

International Nuclear Information System (INIS)

Malamud, Uri; Perets, Hagai B.

2016-01-01

Most observations of polluted white dwarf atmospheres are consistent with accretion of water-depleted planetary material. Among tens of known cases, merely two involve accretion of objects that contain a considerable mass fraction of water. The purpose of this study is to investigate the relative scarcity of these detections. Based on a new and highly detailed model, we evaluate the retention of water inside icy minor planets during the high-luminosity stellar evolution that follows the main sequence. Our model fully considers the thermal, physical, and chemical evolution of icy bodies, following their internal differentiation as well as water depletion, from the moment of their birth and through all stellar evolution phases preceding the formation of the white dwarf. We also account for different initial compositions and formation times. Our results differ from previous studies, which have either underestimated or overestimated water retention. We show that water can survive in a variety of circumstances and in great quantities, and therefore other possibilities are discussed in order to explain the infrequency of water detection. We predict that the sequence of accretion is such that water accretes earlier, and more rapidly, than the rest of the silicate disk, considerably reducing the chance of its detection in H-dominated atmospheres. In He-dominated atmospheres, the scarcity of water detections could be observationally biased. It implies that the accreted material is typically intrinsically dry, which may be the result of the inside-out depopulation sequence of minor planets.

Matrix based method for synthesis of main intensified and integrated distillation sequences

International Nuclear Information System (INIS)

Khalili-Garakani, Amirhossein; Kasiri, Norollah; Ivakpour, Javad

2016-01-01

The objective of many studies in this area has involved access to a column-sequencing algorithm enabling designers and researchers alike to generate a wide range of sequences in a broad search space, and be as mathematically and as automated as possible for programing purposes and with good generality. In the present work an algorithm previously developed by the authors, called the matrix method, has been developed much further. The new version of the algorithm includes thermally coupled, thermodynamically equivalent, intensified, simultaneous heat and mass integrated and divided-wall column sequences which are of gross application and provide vast saving potential both on capital investment, operating costs and energy usage in industrial applications. To demonstrate the much wider searchable space now accessible, a three component separation has been thoroughly examined as a case study, always resulting in an integrated sequence being proposed as the optimum.

TESTING SCALING RELATIONS FOR SOLAR-LIKE OSCILLATIONS FROM THE MAIN SEQUENCE TO RED GIANTS USING KEPLER DATA

Energy Technology Data Exchange (ETDEWEB)

Huber, D.; Bedding, T. R.; Stello, D. [Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney, NSW 2006 (Australia); Hekker, S. [Astronomical Institute ' Anton Pannekoek' , University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands); Mathur, S. [High Altitude Observatory, NCAR, P.O. Box 3000, Boulder, CO 80307 (United States); Mosser, B. [LESIA, CNRS, Universite Pierre et Marie Curie, Universite Denis, Diderot, Observatoire de Paris, 92195 Meudon cedex (France); Verner, G. A.; Elsworth, Y. P.; Hale, S. J.; Chaplin, W. J. [School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT (United Kingdom); Bonanno, A. [INAF Osservatorio Astrofisico di Catania (Italy); Buzasi, D. L. [Eureka Scientific, 2452 Delmer Street Suite 100, Oakland, CA 94602-3017 (United States); Campante, T. L. [Centro de Astrofisica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal); Kallinger, T. [Department of Physics and Astronomy, University of British Columbia, Vancouver (Canada); Silva Aguirre, V. [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, 85748 Garching (Germany); De Ridder, J. [Instituut voor Sterrenkunde, K.U.Leuven (Belgium); Garcia, R. A. [Laboratoire AIM, CEA/DSM-CNRS, Universite Paris 7 Diderot, IRFU/SAp, Centre de Saclay, 91191, Gif-sur-Yvette (France); Appourchaux, T. [Institut d' Astrophysique Spatiale, UMR 8617, Universite Paris Sud, 91405 Orsay Cedex (France); Frandsen, S. [Danish AsteroSeismology Centre (DASC), Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Houdek, G., E-mail: dhuber@physics.usyd.edu.au [Institute of Astronomy, University of Vienna, 1180 Vienna (Austria); and others

2011-12-20

We have analyzed solar-like oscillations in {approx}1700 stars observed by the Kepler Mission, spanning from the main sequence to the red clump. Using evolutionary models, we test asteroseismic scaling relations for the frequency of maximum power ({nu}{sub max}), the large frequency separation ({Delta}{nu}), and oscillation amplitudes. We show that the difference of the {Delta}{nu}-{nu}{sub max} relation for unevolved and evolved stars can be explained by different distributions in effective temperature and stellar mass, in agreement with what is expected from scaling relations. For oscillation amplitudes, we show that neither (L/M){sup s} scaling nor the revised scaling relation by Kjeldsen and Bedding is accurate for red-giant stars, and demonstrate that a revised scaling relation with a separate luminosity-mass dependence can be used to calculate amplitudes from the main sequence to red giants to a precision of {approx}25%. The residuals show an offset particularly for unevolved stars, suggesting that an additional physical dependency is necessary to fully reproduce the observed amplitudes. We investigate correlations between amplitudes and stellar activity, and find evidence that the effect of amplitude suppression is most pronounced for subgiant stars. Finally, we test the location of the cool edge of the instability strip in the Hertzsprung-Russell diagram using solar-like oscillations and find the detections in the hottest stars compatible with a domain of hybrid stochastically excited and opacity driven pulsation.

Cloning and characterization of pre-miR159a and pre-miR1123 from ...

African Journals Online (AJOL)

Although many miRNA genes are conserved across the plant species, the same gene family varies significantly in size and genomic organization in different species. ... Sequence identity matrix suggests 43-82% variation in precursor of Tae AL pre-miR159a (Tae Agra local pre-miR159a) across the species. On the other ...

YSOVAR: Six Pre-main-sequence Eclipsing Binaries in the Orion Nebula Cluster

Science.gov (United States)

2012-06-25

ISOY J053446.01−044922.1i V1448 Ori 17.43c 15.61c 13.88 13.26 12.95 12.73 12.66 12.91 . . . K5c 0.5424125 ISOY J053605.95−050041.2i 2MASS J05360595...identified 12 EB candidates. Four of them, 2MASS 05352184−0546085 (Stassun et al. 2006), V1174 Ori (Stassun et al. 2004), Par1802 (Cargile et al. 2008...Zero points for the photometry were established by reference to data for non-variable stars in our FOV from the Two Micron All Sky Survey ( 2MASS

The complete Einstein Observatory X-ray survey of the Orion Nebula region.

Science.gov (United States)

Gagne, Marc; Caillault, Jean-Pierre

1994-01-01

We have analyzed archival Einstein Observatory images of a roughly 4.5 square degree region centered on the Orion Nebula. In all, 245 distinct X-ray sources have been detected in six High Resolution Imager (HRI) and 17 Imaging Proportional Counter (IPC) observations. An optical database of over 2700 stars has been assembled to search for candidate counterparts to the X-ray sources. Roughly half the X-ray sources are identified with a single Orion Nebula cluster member. The 10 main-sequence O6-B5 cluster stars detected in Orion have X-ray activity levels comparable to field O and B stars. X-ray emission has also been detected in the direction of four main-sequence late-B and early-A type stars. Since the mechanisms producing X-rays in late-type coronae and early-type winds cannot operate in the late-B and early-A type atmospheres, we argue that the observed X-rays, with L(sub X) approximately = 3 x 10(exp 30) ergs/s, are probably produced in the coronae of unseen late-type binary companions. Over 100 X-ray sources have been associated with late-type pre-main sequence stars. The upper envelope of X-ray activity rises sharply from mid-F to late-G, with L(sub x)/L(sub bol) in the range 10(exp -4) to 2 x 10(exp -3) for stars later than approximately G7. We have looked for variability of the late-type cluster members on timescales of a day to a year and find that 1/4 of the stars show significantly variable X-ray emission. A handful of the late-type stars have published rotational periods and spectroscopic rotational velocities; however, we see no correlation between X-ray activity and rotation. Thus, for this sample of pre-main-sequence stars, the large dispersion in X-ray activity does not appear to be caused by the dispersion in rotation, in contrast with results obtained for low-mass main-sequence stars in the Pleiades and pre-main-sequence stars in Taurus-Auriga.

Metabolite ratios in 1H MR spectroscopic imaging of the prostate

NARCIS (Netherlands)

Kobus, T.; Wright, A.J.; Weiland, E.; Heerschap, A.; Scheenen, T.W.J.

2015-01-01

In (1)H MR spectroscopic imaging ((1)H-MRSI) of the prostate the spatial distribution of the signal levels of the metabolites choline, creatine, polyamines, and citrate are assessed. The ratio of choline (plus spermine as the main polyamine) plus creatine over citrate [(Cho+(Spm+)Cr)/Cit] is derived

Comparison of Pre-Analytical FFPE Sample Preparation Methods and Their Impact on Massively Parallel Sequencing in Routine Diagnostics

Science.gov (United States)

Heydt, Carina; Fassunke, Jana; Künstlinger, Helen; Ihle, Michaela Angelika; König, Katharina; Heukamp, Lukas Carl; Schildhaus, Hans-Ulrich; Odenthal, Margarete; Büttner, Reinhard; Merkelbach-Bruse, Sabine

2014-01-01

Over the last years, massively parallel sequencing has rapidly evolved and has now transitioned into molecular pathology routine laboratories. It is an attractive platform for analysing multiple genes at the same time with very little input material. Therefore, the need for high quality DNA obtained from automated DNA extraction systems has increased, especially to those laboratories which are dealing with formalin-fixed paraffin-embedded (FFPE) material and high sample throughput. This study evaluated five automated FFPE DNA extraction systems as well as five DNA quantification systems using the three most common techniques, UV spectrophotometry, fluorescent dye-based quantification and quantitative PCR, on 26 FFPE tissue samples. Additionally, the effects on downstream applications were analysed to find the most suitable pre-analytical methods for massively parallel sequencing in routine diagnostics. The results revealed that the Maxwell 16 from Promega (Mannheim, Germany) seems to be the superior system for DNA extraction from FFPE material. The extracts had a 1.3–24.6-fold higher DNA concentration in comparison to the other extraction systems, a higher quality and were most suitable for downstream applications. The comparison of the five quantification methods showed intermethod variations but all methods could be used to estimate the right amount for PCR amplification and for massively parallel sequencing. Interestingly, the best results in massively parallel sequencing were obtained with a DNA input of 15 ng determined by the NanoDrop 2000c spectrophotometer (Thermo Fisher Scientific, Waltham, MA, USA). No difference could be detected in mutation analysis based on the results of the quantification methods. These findings emphasise, that it is particularly important to choose the most reliable and constant DNA extraction system, especially when using small biopsies and low elution volumes, and that all common DNA quantification techniques can be used for

Comparison of pre-analytical FFPE sample preparation methods and their impact on massively parallel sequencing in routine diagnostics.

Directory of Open Access Journals (Sweden)

Carina Heydt

Full Text Available Over the last years, massively parallel sequencing has rapidly evolved and has now transitioned into molecular pathology routine laboratories. It is an attractive platform for analysing multiple genes at the same time with very little input material. Therefore, the need for high quality DNA obtained from automated DNA extraction systems has increased, especially to those laboratories which are dealing with formalin-fixed paraffin-embedded (FFPE material and high sample throughput. This study evaluated five automated FFPE DNA extraction systems as well as five DNA quantification systems using the three most common techniques, UV spectrophotometry, fluorescent dye-based quantification and quantitative PCR, on 26 FFPE tissue samples. Additionally, the effects on downstream applications were analysed to find the most suitable pre-analytical methods for massively parallel sequencing in routine diagnostics. The results revealed that the Maxwell 16 from Promega (Mannheim, Germany seems to be the superior system for DNA extraction from FFPE material. The extracts had a 1.3-24.6-fold higher DNA concentration in comparison to the other extraction systems, a higher quality and were most suitable for downstream applications. The comparison of the five quantification methods showed intermethod variations but all methods could be used to estimate the right amount for PCR amplification and for massively parallel sequencing. Interestingly, the best results in massively parallel sequencing were obtained with a DNA input of 15 ng determined by the NanoDrop 2000c spectrophotometer (Thermo Fisher Scientific, Waltham, MA, USA. No difference could be detected in mutation analysis based on the results of the quantification methods. These findings emphasise, that it is particularly important to choose the most reliable and constant DNA extraction system, especially when using small biopsies and low elution volumes, and that all common DNA quantification techniques can

Taxonomic and predicted metabolic profiles of the human gut microbiome in pre-Columbian mummies.

Science.gov (United States)

Santiago-Rodriguez, Tasha M; Fornaciari, Gino; Luciani, Stefania; Dowd, Scot E; Toranzos, Gary A; Marota, Isolina; Cano, Raul J

2016-11-01

Characterization of naturally mummified human gut remains could potentially provide insights into the preservation and evolution of commensal and pathogenic microorganisms, and metabolic profiles. We characterized the gut microbiome of two pre-Columbian Andean mummies dating to the 10-15th centuries using 16S rRNA gene high-throughput sequencing and metagenomics, and compared them to a previously characterized gut microbiome of an 11th century AD pre-Columbian Andean mummy. Our previous study showed that the Clostridiales represented the majority of the bacterial communities in the mummified gut remains, but that other microbial communities were also preserved during the process of natural mummification, as shown with the metagenomics analyses. The gut microbiome of the other two mummies were mainly comprised by Clostridiales or Bacillales, as demonstrated with 16S rRNA gene amplicon sequencing, many of which are facultative anaerobes, possibly consistent with the process of natural mummification requiring low oxygen levels. Metagenome analyses showed the presence of other microbial groups that were positively or negatively correlated with specific metabolic profiles. The presence of sequences similar to both Trypanosoma cruzi and Leishmania donovani could suggest that these pathogens were prevalent in pre-Columbian individuals. Taxonomic and functional profiling of mummified human gut remains will aid in the understanding of the microbial ecology of the process of natural mummification. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Some aspects of cool main sequence star ages derived from stellar rotation (gyrochronology)

Science.gov (United States)

Barnes, S. A.; Spada, F.; Weingrill, J.

2016-09-01

Rotation periods for cool stars can be measured with good precision by monitoring starspot light modulation. Observations have shown that the rotation periods of dwarf stars of roughly solar metallicity have such systematic dependencies on stellar age and mass that they can be used to derive reliable ages, a procedure called gyrochronology. We review the method and show illustrative cases, including recent ground- and space-based data. The age uncertainties approach 10 % in the best cases, making them a valuable complement to, and constraint on, asteroseismic or other ages. Edited, updated, and refereed version of a presentation at the WE-Heraeus-Seminar in Bad Honnef, Germany: Reconstructing the Milky Way's History: Spectroscopic Surveys, Asteroseismology and Chemodynamical Models

Spectroscopic study on the stability of morin in aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Bark, Ki Min [Dept. of Chemical Education and Research Institute of Life Science, Gyeongsang National University, Chinju (Korea, Republic of); Im, Seo Eun; Seo, Jung Ja; Park, Ok Hyun; Park, Hyoung Ryun [Dept. of Chemistry, Chonnam National University, Gwangju (Korea, Republic of); Park, Chul Ho [Dept. of Cosmetic Science, Nambu University, Gwangju (Korea, Republic of)

2015-02-15

Morin (3,2,4,5,7-pentahydroxyflavone) is a flavonol conjugated to a resorcinol moiety at the C-2 position, different from many other flavonoids. The UV–vis spectrum of morin in neat water reveals two major absorption bands with maxima at 265 and 387 nm. The substance is stable in acidic solution and neat water. However, its absorption maximum at 387 nm continuously shifts to longer wavelengths and new peaks appeared at wavelengths of 312 nm with increasing pH of the solution. The shape of the absorption spectrum of morin depends on the storage time at a given pH, indicating the occurrence of other successive chemical reactions. The fluorescence spectroscopic results also prove that new conjugated double bonds are formed in the deaerated basic solution at the initial state and decompose with time. This behavior indicates that morin is very unstable, and therefore its decomposition occurs by a sequence of multistep reactions in basic solution. Probable reaction pathways for the reaction are suggested based on the spectroscopic results.

Verifying reddening and extinction for Gaia DR1 TGAS main sequence stars

Science.gov (United States)

Gontcharov, George A.; Mosenkov, Aleksandr V.

2017-12-01

We compare eight sources of reddening and extinction estimates for approximately 60 000 Gaia DR1 Tycho-Gaia Astrometric Solution (TGAS) main sequence stars younger than 3 Gyr with a relative error of the Gaia parallax less than 0.1. For the majority of the stars, the best 2D dust emission-based reddening maps show considerable differences between the reddening to infinity and the one calculated to the stellar distance using the barometric law of the dust distribution. This proves that the majority of the TGAS stars are embedded in the Galactic dust layer and a proper 3D treatment of the reddening/extinction is required to calculate their dereddened colours and absolute magnitudes reliably. Sources with 3D estimates of reddening are tested in their ability to put the stars among the PARSEC and MIST theoretical isochrones in the Hertzsprung-Russell diagram based on the precise Gaia, Tycho-2, 2MASS and WISE photometry. Only the reddening/extinction estimates by Arenou et al. and Gontcharov, being appropriate for nearby stars within 280 pc, provide both the minimal number of outliers bluer than any reasonable isochrone and the correct number of stars younger than 3 Gyr in agreement with the Besançon Galaxy model.

Spectroscopic Diagnosis of Arsenic Contamination in Agricultural Soils

Directory of Open Access Journals (Sweden)

Tiezhu Shi

2017-05-01

Full Text Available This study investigated the abilities of pre-processing, feature selection and machine-learning methods for the spectroscopic diagnosis of soil arsenic contamination. The spectral data were pre-processed by using Savitzky-Golay smoothing, first and second derivatives, multiplicative scatter correction, standard normal variate, and mean centering. Principle component analysis (PCA and the RELIEF algorithm were used to extract spectral features. Machine-learning methods, including random forests (RF, artificial neural network (ANN, radial basis function- and linear function- based support vector machine (RBF- and LF-SVM were employed for establishing diagnosis models. The model accuracies were evaluated and compared by using overall accuracies (OAs. The statistical significance of the difference between models was evaluated by using McNemar’s test (Z value. The results showed that the OAs varied with the different combinations of pre-processing, feature selection, and classification methods. Feature selection methods could improve the modeling efficiencies and diagnosis accuracies, and RELIEF often outperformed PCA. The optimal models established by RF (OA = 86%, ANN (OA = 89%, RBF- (OA = 89% and LF-SVM (OA = 87% had no statistical difference in diagnosis accuracies (Z < 1.96, p < 0.05. These results indicated that it was feasible to diagnose soil arsenic contamination using reflectance spectroscopy. The appropriate combination of multivariate methods was important to improve diagnosis accuracies.

Spectroscopic classification of transients

DEFF Research Database (Denmark)

Stritzinger, M. D.; Fraser, M.; Hummelmose, N. N.

2017-01-01

We report the spectroscopic classification of several transients based on observations taken with the Nordic Optical Telescope (NOT) equipped with ALFOSC, over the nights 23-25 August 2017.......We report the spectroscopic classification of several transients based on observations taken with the Nordic Optical Telescope (NOT) equipped with ALFOSC, over the nights 23-25 August 2017....

TIME-SERIES PHOTOMETRY OF STARS IN AND AROUND THE LAGOON NEBULA. I. ROTATION PERIODS OF 290 LOW-MASS PRE-MAIN-SEQUENCE STARS IN NGC 6530

International Nuclear Information System (INIS)

Henderson, Calen B.; Stassun, Keivan G.

2012-01-01

We have conducted a long-term, wide-field, high-cadence photometric monitoring survey of ∼50,000 stars in the Lagoon Nebula H II region. This first paper presents rotation periods for 290 low-mass stars in NGC 6530, the young cluster illuminating the nebula, and for which we assemble a catalog of infrared and spectroscopic disk indicators, estimated masses and ages, and X-ray luminosities. The distribution of rotation periods we measure is broadly uniform for 0.5 days X /L bol ≈ –3.3). However, we find a significant positive correlation between L X /L bol and corotation radius, suggesting that the observed X-ray luminosities are regulated by centrifugal stripping of the stellar coronae. The period-mass relationship in NGC 6530 is broadly similar to that of the Orion Nebula Cluster (ONC), but the slope of the relationship among the slowest rotators differs from that in the ONC and other young clusters. We show that the slope of the period-mass relationship for the slowest rotators can be used as a proxy for the age of a young cluster, and we argue that NGC 6530 may be slightly younger than the ONC, making it a particularly important touchstone for models of angular momentum evolution in young, low-mass stars.

Systems budgets architecture and development for the Maunakea Spectroscopic Explorer

Science.gov (United States)

Mignot, Shan; Flagey, Nicolas; Szeto, Kei; Murowinski, Rick; McConnachie, Alan

2016-08-01

The Maunakea Spectroscopic Explorer (MSE) project is an enterprise to upgrade the existing Canada-France- Hawaii observatory into a spectroscopic facility based on a 10 meter-class telescope. As such, the project relies on engineering requirements not limited only to its instruments (the low, medium and high resolution spectrographs) but for the whole observatory. The science requirements, the operations concept, the project management and the applicable regulations are the basis from which these requirements are initially derived, yet they do not form hierarchies as each may serve several purposes, that is, pertain to several budgets. Completeness and consistency are hence the main systems engineering challenges for such a large project as MSE. Special attention is devoted to ensuring the traceability of requirements via parametric models, derivation documents, simulations, and finally maintaining KAOS diagrams and a database under IBM Rational DOORS linking them together. This paper will present the architecture of the main budgets under development and the associated processes, expand to highlight those that are interrelated and how the system, as a whole, is then optimized by modelling and analysis of the pertinent system parameters.

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

Energy Technology Data Exchange (ETDEWEB)

Yanny, Brian; /Fermilab; Rockosi, Constance; /UC, Santa Cruz; Newberg, Heidi Jo; /Rensselaer Poly.; Knapp, Gillian R.; /Princeton U.; Adelman-McCarthy, Jennifer K.; /Fermilab; Alcorn, Bonnie; /Fermilab; Allam, Sahar S.; /Fermilab; Prieto, Carlos Allende; /Texas U. /University Coll. London; An, Deokkeun; /Ohio State U.; Anderson, Kurt S.J.; /Apache Point Observ. /New Mexico State U.; 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.

Main sequence of the metal-poor globular cluster M30 (NGC 7099)

International Nuclear Information System (INIS)

Alcaino, G.; Liller, W.

1980-01-01

We present photographic photometry for 673 stars in the metal-poor globular cluster M30 (NGC 7099). The Racine wedge was used with the CTIO 1-m Yale telescope (Δm=3/sup m/.60), the CTIO 4-m telescope (Δm=6/sup m/.83), and the ESO 3.6-m telescope (Δm=4/sup m/.12) to extend the photoelectric limit from Vapprox. =16.3 to Vapprox. =20.4. For the main-sequence turn-off, we have determined its position to lie at V=18.4 +- 0.1 (m.e.) and B-V=0.49 +- 0.03 (m.e.). From these values, we calculate the intrinsic values M/sub v/ =3.87 and (B-V) 0 =0.47. For the cluster as a whole, we derive a distance modulus (m-M)/sub V/=14.53 +- 0.15 and reddening E(B-V)=0.02 +- 0.02. Using the models of Iben and Rood [Astrophys. J. 159, 605 (1970)] and the isochrones of Demarque and McClure [(1977), in Evolution of Galaxies and Stellar Populations, edited by B. Tinsley and R. B. Larson (Yale University Observatory, New Haven), p. 199], we deduce the cluster's age to be 14.5( +- 4.0) x 10 9 yr. The large uncertainty in this value emphasizes the dire need for more work on cluster evolution

NEW PRECISION ORBITS OF BRIGHT DOUBLE-LINED SPECTROSCOPIC BINARIES. IV. 66 ANDROMEDAE, HR 6979, AND HR 9059

International Nuclear Information System (INIS)

Fekel, Francis C.; Williamson, Michael H.; Tomkin, Jocelyn

2010-01-01

We have determined improved spectroscopic orbits for three double-lined binaries, 66 And (F4 V), HR 6979 (Am), and HR 9059 (F5 IV) using radial velocities from the 2.1 m telescope at McDonald Observatory, the coude feed telescope at Kitt Peak National Observatory, and 2 m telescope at Fairborn Observatory. The orbital periods range from 11.0 to 14.3 days, and all three systems have eccentric orbits. The new orbital dimensions (a 1 sin i and a 2 sin i) and minimum masses (m 1 sin 3 i and m 2 sin 3 i) have accuracies of 0.2% or better. All six components of the three binary systems are rotating more slowly than their predicted pseudosynchronous rotational velocities. Hipparcos photometry of HR 9059 shows that this system has partial eclipses. Its components are nearly identical in mass and are at the very end of their main-sequence lifetimes or perhaps have just begun to traverse the Hertsprung gap.

MicroRNA categorization using sequence motifs and k-mers.

Science.gov (United States)

Yousef, Malik; Khalifa, Waleed; Acar, İlhan Erkin; Allmer, Jens

2017-03-14

Post-transcriptional gene dysregulation can be a hallmark of diseases like cancer and microRNAs (miRNAs) play a key role in the modulation of translation efficiency. Known pre-miRNAs are listed in miRBase, and they have been discovered in a variety of organisms ranging from viruses and microbes to eukaryotic organisms. The computational detection of pre-miRNAs is of great interest, and such approaches usually employ machine learning to discriminate between miRNAs and other sequences. Many features have been proposed describing pre-miRNAs, and we have previously introduced the use of sequence motifs and k-mers as useful ones. There have been reports of xeno-miRNAs detected via next generation sequencing. However, they may be contaminations and to aid that important decision-making process, we aimed to establish a means to differentiate pre-miRNAs from different species. To achieve distinction into species, we used one species' pre-miRNAs as the positive and another species' pre-miRNAs as the negative training and test data for the establishment of machine learned models based on sequence motifs and k-mers as features. This approach resulted in higher accuracy values between distantly related species while species with closer relation produced lower accuracy values. We were able to differentiate among species with increasing success when the evolutionary distance increases. This conclusion is supported by previous reports of fast evolutionary changes in miRNAs since even in relatively closely related species a fairly good discrimination was possible.

A SPECTROSCOPICALLY NORMAL TYPE Ic SUPERNOVA FROM A VERY MASSIVE PROGENITOR

International Nuclear Information System (INIS)

Valenti, Stefano; Pastorello, Andrea; Benetti, Stefano; Cappellaro, Enrico; Tomasella, Lina; Turatto, Massimo; Taubenberger, Stefan; Aramyan, Levon; Botticella, Maria Teresa; Fraser, Morgan; Smartt, Stephen J.; Magill, Lindsay; Kotak, Rubina; Wright, Darryl E.; Elias-Rosa, Nancy; Ergon, Mattias; Sollerman, Jesper; Magnier, Eugene; Price, Paul A.

2012-01-01

We present observations of the Type Ic supernova (SN Ic) 2011bm spanning a period of about one year. The data establish that SN 2011bm is a spectroscopically normal SN Ic with moderately low ejecta velocities and with a very slow spectroscopic and photometric evolution (more than twice as slow as SN 1998bw). The Pan-STARRS1 retrospective detection shows that the rise time from explosion to peak was ∼40 days in the R band. Through an analysis of the light curve and the spectral sequence, we estimate a kinetic energy of ∼7-17 foe and a total ejected mass of ∼7-17 M ☉ , 5-10 M ☉ of which is oxygen and 0.6-0.7 M ☉ is 56 Ni. The physical parameters obtained for SN 2011bm suggest that its progenitor was a massive star of initial mass 30-50 M ☉ . The profile of the forbidden oxygen lines in the nebular spectra shows no evidence of a bi-polar geometry in the ejected material.

Pre: Surgical orthopedic pre-maxillary alignment in bilateral cleft lip and palate patient

Directory of Open Access Journals (Sweden)

Vijaya Prasad Kamavaram Ellore

2012-01-01

Full Text Available Pre-surgical orthopedic appliances are mainly used to retract and align the protruded and deviated pre-maxilla and to facilitate initial lip repair. This article presents a case report of a five year old male child patient with bilateral cleft lip and palate in whom a special custom made pre-surgical orthopedic appliance was delivered. Use of a special custom made presurgical orthopedic appliance for repositioning pre-maxilla in bilateral cleft lip and palate patient is discussed in this article.

Spectroscopic properties for identifying sapphire samples from Ban Bo Kaew, Phrae Province, Thailand

Science.gov (United States)

Mogmued, J.; Monarumit, N.; Won-in, K.; Satitkune, S.

2017-09-01

Gemstone commercial is a high revenue for Thailand especially ruby and sapphire. Moreover, Phrae is a potential gem field located in the northern part of Thailand. The studies of spectroscopic properties are mainly to identify gemstone using advanced techniques (e.g. UV-Vis-NIR spectrophotometry, FTIR spectrometry and Raman spectroscopy). Typically, UV-Vis-NIR spectrophotometry is a technique to study the cause of color in gemstones. FTIR spectrometry is a technique to study the functional groups in gem-materials. Raman pattern can be applied to identify the mineral inclusions in gemstones. In this study, the natural sapphires from Ban Bo Kaew were divided into two groups based on colors including blue and green. The samples were analyzed by UV-Vis-NIR spectrophotometer, FTIR spectrometer and Raman spectroscope for studying spectroscopic properties. According to UV-Vis-NIR spectra, the blue sapphires show higher Fe3+/Ti4+ and Fe2+/Fe3+ absorption peaks than those of green sapphires. Otherwise, green sapphires display higher Fe3+/Fe3+ absorption peaks than blue sapphires. The FTIR spectra of both blue and green sapphire samples show the absorption peaks of -OH,-CH and CO2. The mineral inclusions such as ferrocolumbite and rutile in sapphires from this area were observed by Raman spectroscope. The spectroscopic properties of sapphire samples from Ban Bo Kaew, Phrae Province, Thailand are applied to be the specific evidence for gemstone identification.

Application of spectroscopic techniques for the study of paper documents: A survey

International Nuclear Information System (INIS)

Manso, M.; Carvalho, M.L.

2009-01-01

For many centuries paper was the main material for recording cultural achievements all over the world. Paper is mostly made from cellulose with small amounts of organic and inorganic additives, which allow its identification and characterization and may also contribute to its degradation. Prior to 1850, paper was made entirely from rags, using hemp, flax and cotton fibres. After this period, due to the enormous increase in demand, wood pulp began to be commonly used as raw material, resulting in rapid degradation of paper. Spectroscopic techniques represent one of the most powerful tools to investigate the constituents of paper documents in order to establish its identification and its state of degradation. This review describes the application of selected spectroscopic techniques used for paper characterization and conservation. The spectroscopic techniques that have been used and will be reviewed include: Fourier-Transform Infrared spectroscopy, Raman spectroscopy, Nuclear Magnetic Resonance spectroscopy, X-Ray spectroscopy, Laser-based Spectroscopy, Inductively Coupled Mass Spectroscopy, Laser ablation, Atomic Absorption Spectroscopy and X-Ray Photoelectron Spectroscopy.

THE MID-INFRARED AND NEAR-ULTRAVIOLET EXCESS EMISSIONS OF QUIESCENT GALAXIES ON THE RED SEQUENCE

International Nuclear Information System (INIS)

Ko, Jongwan; Lee, Jong Chul; Hwang, Ho Seong; Sohn, Young-Jong

2013-01-01

We study the mid-infrared (IR) and near-ultraviolet (UV) excess emissions of spectroscopically selected quiescent galaxies on the optical red sequence. We use the Wide-field Infrared Survey Explorer mid-IR and Galaxy Evolution Explorer near-UV data for a spectroscopic sample of galaxies in the Sloan Digital Sky Survey Data Release 7 to study the possible connection between quiescent red-sequence galaxies with and without mid-IR/near-UV excess. Among 648 12 μm detected quiescent red-sequence galaxies without Hα emission, 26% and 55% show near-UV and mid-IR excess emissions, respectively. When we consider only bright (M r n 4000 than those without mid-IR and near-UV excess emissions. We also find that mid-IR weighted mean stellar ages of quiescent red-sequence galaxies with mid-IR excess are larger than those with near-UV excess, and smaller than those without mid-IR and near-UV excess. The environmental dependence of the fraction of quiescent red-sequence galaxies with mid-IR and near-UV excess seems strong even though the trends of quiescent red-sequence galaxies with near-UV excess differ from those with mid-IR excess. These results indicate that the recent star formation traced by near-UV (∼< 1 Gyr) and mid-IR (∼< 2 Gyr) excess is not negligible among nearby, quiescent, red, early-type galaxies. We suggest a possible evolutionary scenario of quiescent red-sequence galaxies from quiescent red-sequence galaxies with near-UV excess to those with mid-IR excess to those without near-UV and mid-IR excess.

Making Sense of Atmospheric Models and Fundamental Stellar Properties at the Bottom of the Main Sequence

Science.gov (United States)

Dieterich, Sergio; Henry, Todd; Jao, W.-C.; Washington, Robert; Silverstein, Michele; Winters, J.; RECONS

2018-01-01

We present a detailed comparison of atmospheric model predictions and photometric observations for late M and L dwarfs. We discuss which wavelength regions are best for determining the fundamental properties of these cool stellar and substellar atmospheres and use this analysis to refine the HR diagram for the hydrogen burning limit first presented in 2014. We also add several new objects to the HR diagram and find little qualitative difference in the HR diagram's overall morphology when compared to our 2014 results. The L2 dwarf 2MASS 0523-1403 remains the smallest hydrogen burning star for which we calculated a radius, thus likely indicating the end of the stellar main sequence. This work is supported by the NSF Astronomy and Astrophysics Postdoctoral Fellowship program through grant AST-1400680.

Aristotelian pre-Socratics, A glance at Aristotle's Narrative from pre-Socratics

OpenAIRE

Mehdi Qavam Safari; M.B Ghomi

2015-01-01

In this article, it's tried to study Aristotle's narrative of  pre-Socratics on the base of Aristotle's texts and mainly using  metaphysics, physics, genesis and decadence books. It is also tried to show how Aristotle has interpreted all the pre-Socratics in one way and on the base of his own philosophy framework. He interprets pre-Socratic Arche as an element that means comprehensive matter which is nothing itself, but everything is combination of it and even considers that as substance and ...

T1 Gd-enhanced compared with CISS sequences in retinoblastoma: superiority of T1 sequences in evaluation of tumour extension

Energy Technology Data Exchange (ETDEWEB)

Gizewski, Elke R.; Wanke, Isabel; Guengoer, Ali-Riza; Forsting, Michael [University Hospital, Department of Diagnostic and Interventional Neuroradiology, Essen (Germany); Jurklies, Christine [University Hospital Essen, Department of Ophthalmology (Germany)

2005-01-01

Background As adequate therapy for retinoblastoma in young children depends on infiltration of extra-retinal structures, diagnostic modalities play an essential role. Methods: In this widely extended study, 80 children with retinoblastoma were studied with MRI (standard fat-suppressed Gd-enhanced T1, T2 thin-slice sequences (additionally with small loop surface coil), constructive interference in steady state (CISS) sequence covering the orbita). The images were analysed by two blinded neuroradiologists. Histology was used as the gold standard. MRI assumed infiltration of extra-retinal structures in 13 of 80 patients of which ten were confirmed by histology. Affected extra-retinal structures were: optic nerve (five, of which two were on CISS and three on T1 with higher image resolution using the surface coil), scleral infiltration (five, of which four on CISS and T1) and ciliary body infiltration (one on CISS and T1). Another 61 enucleated patients did not have any extra-retinal infiltration in histology. The CISS sequence with multiplanar reconstruction was mainly helpful in revealing exact three-dimensional tumour extension with excellent clinical acceptance and pre-surgical planning but T1 fat-suppressed Gd-enhanced images were superior in revealing exact tumour extension. CISS sequences allow to produce excellent anatomical images and to perform multiplanar reconstruction to better demonstrate tumour extension. However, T1-weighted sequences after contrast application are more sensitive (60 versus 40%) in detecting infiltration of the optic nerve but equal in detecting scleral infiltration. (orig.)

YOUNG STELLAR CLUSTERS CONTAINING MASSIVE YOUNG STELLAR OBJECTS IN THE VVV SURVEY

Energy Technology Data Exchange (ETDEWEB)

Borissova, J.; Alegría, S. Ramírez; Kurtev, R.; Medina, N.; Navarro, C.; Kuhn, M.; Gromadzki, M.; Retamales, G.; Fernandez, M. A.; Agurto-Gangas, C.; Amigo, P. [Instituto de Física y Astronomía, Universidad de Valparaíso, Av. Gran Bretaña 1111, Playa Ancha, Casilla 5030 (Chile); Alonso, J.; Decany, I. [Millennium Institute of Astrophysics (MAS), Santiago (Chile); Lucas, P. W.; Pena, C. Contreras; Thompson, M. A. [Centre for Astrophysics Research, Science and Technology Research Institute, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); Chené, A.-N. [Gemini Observatory, Northern Operations Center, 670 N. A’ohoku Place, Hilo, HI 96720 (United States); Minniti, D. [Departamento de Ciencias Físicas, Universidad Andres Bello, Republica 220, Santiago (Chile); Catelan, M. [Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 22 (Chile); Morales, E. F. E., E-mail: jura.borissova@uv.cl [Max-Planck-Institute for Astronomy (Germany)

2016-09-01

The purpose of this research is to study the connections of the global properties of eight young stellar clusters projected in the Vista Variables in the Via Lactea (VVV) ESO Large Public Survey disk area and their young stellar object (YSO) populations. The analysis is based on the combination of spectroscopic parallax-based reddening and distance determinations with main-sequence and pre-main-sequence ishochrone fitting to determine the basic parameters (reddening, age, distance) of the sample clusters. The lower mass limit estimations show that all clusters are low or intermediate mass (between 110 and 1800  M {sub ⊙}), the slope Γ of the obtained present-day mass functions of the clusters is close to the Kroupa initial mass function. The YSOs in the cluster’s surrounding fields are classified using low resolution spectra, spectral energy distribution fits with theoretical predictions, and variability, taking advantage of multi-epoch VVV observations. All spectroscopically confirmed YSOs (except one) are found to be massive (more than 8 M {sub ⊙}). Using VVV and GLIMPSE color–color cuts we have selected a large number of new YSO candidates, which are checked for variability and 57% are found to show at least low-amplitude variations. In few cases it was possible to distinguish between YSO and AGB classifications on the basis of light curves.

Characterization of lignin during oxidative and hydrothermal pre-treatment processes of wheat straw and corn stover.

Science.gov (United States)

Kaparaju, Prasad; Felby, Claus

2010-05-01

The objective of the study was to characterize and map changes in lignin during hydrothermal and wet explosion pre-treatments of wheat straw and corn stover. Chemical composition, microscopic (atomic force microscopy and scanning electron microscopy) and spectroscopic (attenuated total reflectance Fourier transform infrared spectroscopy, ATR-FTIR) analyses were performed. Results showed that both pre-treatments improved the cellulose and lignin content with substantial removal of hemicellulose in the pre-treated biomasses. These values were slightly higher for hydrothermal compared to wet explosion pre-treatment. ATR-FTIR analyses also confirmed these results. Microscopic analysis showed that pre-treatments affected the biomass by partial difibration. Lignin deposition on the surface of the hydrothermally pre-treated fibre was very distinct while severe loss of fibril integrity was noticed with wet exploded fibre. The present study thus revealed that the lignin cannot be removed by the studied pre-treatments. However, both pre-treatments improved the accessibility of the biomass towards enzymatic hydrolysis. Copyright 2009 Elsevier Ltd. All rights reserved.

Pre-Carboniferous sedimentary sequences of the northeastern flank of the Parana basin and southwestern of the Parnaiba basin and its uraniferous possibilites

International Nuclear Information System (INIS)

Andrade, S.M. de; Camarco, P.E.N.

1982-01-01

The analyses of the already existent geological data of the northeastern flank of the Parana Basin and the Southwestern flank of the Parnaiba Basin, added to new data from drilling and geological mapping allowed a better knowledge of the stratigraphy of the pre-carboniferous sedimentary sequences (silurian and devonian ages) as well as provided subsidies for the definition of its uranium possibilites. Besides the already known uranium deposits of the Ponta Grossa Formation, is should be considered as worth while of prospecting the Pimenteiras Formation. (Author) [pt

Analysis of the Sequences, Structures, and Functions of Product-Releasing Enzyme Domains in Fungal Polyketide Synthases

Directory of Open Access Journals (Sweden)

Lu Liu

2017-09-01

Full Text Available Product-releasing enzyme (PRE domains in fungal non-reducing polyketide synthases (NR-PKSs play a crucial role in catalysis and editing during polyketide biosynthesis, especially accelerating final biosynthetic reactions accompanied with product offloading. However, up to date, the systematic knowledge about PRE domains is deficient. In the present study, the relationships between sequences, structures, and functions of PRE domains were analyzed with 574 NR-PKSs of eight groups (I–VIII. It was found that the PRE domains in NR-PKSs could be mainly classified into three types, thioesterase (TE, reductase (R, and metallo-β-lactamase-type TE (MβL-TE. The widely distributed TE or TE-like domains were involved in NR-PKSs of groups I–IV, VI, and VIII. The R domains appeared in NR-PKSs of groups IV and VII, while the physically discrete MβL-TE domains were employed by most NR-PKSs of group V. The changes of catalytic sites and structural characteristics resulted in PRE functional differentiations. The phylogeny revealed that the evolution of TE domains was accompanied by complex functional divergence. The diverse sequence lengths of TE lid-loops affected substrate specificity with different chain lengths. The volume diversification of TE catalytic pockets contributed to catalytic mechanisms with functional differentiations. The above findings may help to understand the crucial catalysis of fungal aromatic polyketide biosyntheses and govern recombination of NR-PKSs to obtain unnatural target products.

MAGNETIC ACTIVITY ANALYSIS FOR A SAMPLE OF G-TYPE MAIN SEQUENCE KEPLER TARGETS

Energy Technology Data Exchange (ETDEWEB)

Mehrabi, Ahmad [Department of Physics, Bu Ali Sina University, 65178, 016016, Hamedan (Iran, Islamic Republic of); He, Han [National Astronomical Observatories, Chinese Academy of Sciences, Beijing (China); Khosroshahi, Habib, E-mail: mehrabi@basu.ac.ir [School of Astronomy, Institute for Research in Fundamental Sciences (IPM), 19395-5531, Tehran (Iran, Islamic Republic of)

2017-01-10

The variation of a stellar light curve owing to rotational modulation by magnetic features (starspots and faculae) on the star’s surface can be used to investigate the magnetic properties of the host star. In this paper, we use the periodicity and magnitude of the light-curve variation as two proxies to study the stellar magnetic properties for a large sample of G-type main sequence Kepler targets, for which the rotation periods were recently determined. By analyzing the correlation between the two magnetic proxies, it is found that: (1) the two proxies are positively correlated for most of the stars in our sample, and the percentages of negative, zero, and positive correlations are 4.27%, 6.81%, and 88.91%, respectively; (2) negative correlation stars cannot have a large magnitude of light-curve variation; and (3) with the increase of rotation period, the relative number of positive correlation stars decreases and the negative correlation one increases. These results indicate that stars with shorter rotation period tend to have positive correlation between the two proxies, and a good portion of the positive correlation stars have a larger magnitude of light-curve variation (and hence more intense magnetic activities) than negative correlation stars.

Sequencing Events: Exploring Art and Art Jobs.

Science.gov (United States)

Stephens, Pamela Geiger; Shaddix, Robin K.

2000-01-01

Presents an activity for upper-elementary students that correlates the actions of archaeologists, patrons, and artists with the sequencing of events in a logical order. Features ancient Egyptian art images. Discusses the preparation of materials, motivation, a pre-writing activity, and writing a story in sequence. (CMK)

How Dusty Is Alpha Centauri? Excess or Non-excess over the Infrared Photospheres of Main-sequence Stars

Science.gov (United States)

Wiegert, J.; Liseau, R.; Thebault, P.; Olofsson, G.; Mora, A.; Bryden, G.; Marshall, J. P.; Eiroa, C.; Montesinos, B.; Ardila, D.;

PHIBSS: MOLECULAR GAS CONTENT AND SCALING RELATIONS IN z ∼ 1-3 MASSIVE, MAIN-SEQUENCE STAR-FORMING GALAXIES

International Nuclear Information System (INIS)

Tacconi, L. J.; Genzel, R.; Wuyts, S.; Förster Schreiber, N. M.; Gracia-Carpio, J.; Lutz, D.; Saintonge, A.; Neri, R.; Cox, P.; Combes, F.; Bolatto, A.; Cooper, M. C.; Bournaud, F.; Burkert, A.; Comerford, J.; Davis, M.; Newman, S.; García-Burillo, S.; Naab, T.; Omont, A.

2013-01-01

We present PHIBSS, the IRAM Plateau de Bure high-z blue sequence CO 3-2 survey of the molecular gas properties in massive, main-sequence star-forming galaxies (SFGs) near the cosmic star formation peak. PHIBSS provides 52 CO detections in two redshift slices at z ∼ 1.2 and 2.2, with log(M * (M ☉ )) ≥ 10.4 and log(SFR(M ☉ /yr)) ≥ 1.5. Including a correction for the incomplete coverage of the M * -SFR plane, and adopting a ''Galactic'' value for the CO-H 2 conversion factor, we infer average gas fractions of ∼0.33 at z ∼ 1.2 and ∼0.47 at z ∼ 2.2. Gas fractions drop with stellar mass, in agreement with cosmological simulations including strong star formation feedback. Most of the z ∼ 1-3 SFGs are rotationally supported turbulent disks. The sizes of CO and UV/optical emission are comparable. The molecular-gas-star-formation relation for the z = 1-3 SFGs is near-linear, with a ∼0.7 Gyr gas depletion timescale; changes in depletion time are only a secondary effect. Since this timescale is much less than the Hubble time in all SFGs between z ∼ 0 and 2, fresh gas must be supplied with a fairly high duty cycle over several billion years. At given z and M * , gas fractions correlate strongly with the specific star formation rate (sSFR). The variation of sSFR between z ∼ 0 and 3 is mainly controlled by the fraction of baryonic mass that resides in cold gas.

Approach to the E-ELT dome and main structure challenges

Science.gov (United States)

Bilbao, Armando; Murga, Gaizka; Gómez, Celia; Llarena, Javier

2014-07-01

The E-ELT as a whole could be classified as an extremely challenging project. More precisely, it should be defined as an array of many different sub-challenges, which comprise technical, logistical and managerial matters. This paper reviews some of these critical challenges, in particular those related to the Dome and the Main Structure, suggesting ways to face them in the most pragmatic way possible. Technical challenges for the Dome and the Main Structure are mainly related to the need to upscale current design standards to an order of magnitude larger design. Trying a direct design escalation is not feasible; it would not work. A design effort is needed to cross hybridize current design standards with technologies coming from other different applications. Innovative design is therefore not a wish but a must. And innovative design comes along with design risk. Design risk needs to be tackled from two angles: on the one hand through thorough design validation analysis and on the other hand through extensive pre-assembly and testing. And, once again, full scale integrated pre-assembly and testing of extremely large subsystems is not always possible. Therefore, defining a comprehensive test plan for critical components, critical subsystems and critical subassemblies becomes essential. Logistical challenges are linked to the erection site. Cerro Armazones is a remote site and this needs to be considered when evaluating transport and erection requirements. But it is not only the remoteness of the site that needs to be considered. The size of both Dome and Main Structure require large construction cranes and a well defined erection plan taking into account pre-assembly strategies, limited plan area utilization, erection sequence, erection stability during intermediate stages and, very specifically, efficient coordination between the Dome and the Main Structure erection processes. Managerial issues pose another set of challenges in this project. Both the size of the

Microscale Syntheses, Reactions, and 1H NMR Spectroscopic Investigations of Square Planar Macrocyclic Tetraamido-N Cu(III) Complexes Relevant to Green Chemistry

Science.gov (United States)

Uffelman, Erich S.; Doherty, Jonathan R.; Schulze, Carl; Burke, Amy L.; Bonnema, Kristen R.; Watson, Tanya T.; Lee, Daniel W., III

2004-01-01

Microscale fusions, description, and spectroscopic analysis of the reactivity of a square planar Cu(III) complex significant to green chemistry, are presented. The experiment also includes nine focal points on which pre-lab and post-lab questions are based, and the final exams reflect the students' comprehension of these and other features of…

EXAMINATION OF THE MASS-DEPENDENT Li DEPLETION HYPOTHESIS BY THE Li ABUNDANCES OF THE VERY METAL-POOR DOUBLE-LINED SPECTROSCOPIC BINARY G166-45

International Nuclear Information System (INIS)

Aoki, Wako; Ito, Hiroko; Tajitsu, Akito

2012-01-01

The Li abundances of the two components of the very metal-poor ([Fe/H] –2.5) double-lined spectroscopic binary G166-45 (BD+26°2606) are determined separately based on high-resolution spectra obtained with the Subaru Telescope High Dispersion Spectrograph and its image slicer. From the photometric colors and the mass ratio, the effective temperatures of the primary and secondary components are estimated to be 6350 ± 100 K and 5830 ± 170 K, respectively. The Li abundance of the primary (A(Li) = 2.23) agrees well with the Spite plateau value, while that of the secondary is slightly lower (A(Li) = 2.11). Such a discrepancy of the Li abundances between the two components is previously found in the extremely metal-poor, double-lined spectroscopic binary CS 22876-032; however, the discrepancy in G166-45 is much smaller. The results agree with the trends found for Li abundance as a function of effective temperature (and of stellar mass) of main-sequence stars with –3.0 eff ∼ 5800 K is not particularly large in this metallicity range. The significant Li depletion found in CS 22876-032B is a phenomenon only found in the lowest metallicity range ([Fe/H] < –3).

Raman spectroscopic biochemical mapping of tissues

Science.gov (United States)

Stone, Nicholas; Hart Prieto, Maria C.; Kendall, Catherine A.; Shetty, Geeta; Barr, Hugh

2006-02-01

Advances in technologies have brought us closer to routine spectroscopic diagnosis of early malignant disease. However, there is still a poor understanding of the carcinogenesis process. For example it is not known whether many cancers follow a logical sequence from dysplasia, to carcinoma in situ, to invasion. Biochemical tissue changes, triggered by genetic mutations, precede morphological and structural changes. These can be probed using Raman or FTIR microspectroscopy and the spectra analysed for biochemical constituents. Local microscopic distribution of various constituents can then be visualised. Raman mapping has been performed on a number of tissues including oesophagus, breast, bladder and prostate. The biochemical constituents have been calculated at each point using basis spectra and least squares analysis. The residual of the least squares fit indicates any unfit spectral components. The biochemical distribution will be compared with the defined histopathological boundaries. The distribution of nucleic acids, glycogen, actin, collagen I, III, IV, lipids and others appear to follow expected patterns.

X-ray sources in regions of star formation. I. The naked T Tauri stars

International Nuclear Information System (INIS)

Walter, F.M.

1986-01-01

Einstein X-ray observations of regions of active star formation in Taurus, Ophiuchus, and Corona Australis show a greatly enhanced surface density of stellar X-ray sources over that seen in other parts of the sky. Many of the X-ray sources are identified with low-mass, pre-main-sequence stars which are not classical T Tauri stars. The X-ray, photometric, and spectroscopic data for these stars are discussed. Seven early K stars in Oph and CrA are likely to be 1-solar-mass post-T Tauri stars with ages of 10-million yr. The late K stars in Taurus are not post-T Tauri, but naked T Tauri stars, which are coeval with the T Tauri stars, differing mainly in the lack of a circumstellar envelope. 72 references

Sub-THz spectroscopic characterization of vibrational modes in artificially designed DNA monocrystal

International Nuclear Information System (INIS)

Sizov, Igor; Rahman, Masudur; Gelmont, Boris; Norton, Michael L.; Globus, Tatiana

2013-01-01

Highlights: • Sub-THz spectroscopy is used to characterize artificially designed DNA monocrystal. • Results are obtained using a novel near field, RT, frequency domain spectrometer. • Narrow resonances of 0.1 cm −1 width in absorption spectra of crystal are observed. • Signature measured between 310 and 490 GHz is reproducible and well resolved. • Absorption pattern is explained in part by simulation results from dsDNA fragment. - Abstract: Sub-terahertz (sub-THz) vibrational spectroscopy is a new spectroscopic branch for characterizing biological macromolecules. In this work, highly resolved sub-THz resonance spectroscopy is used for characterizing engineered molecular structures, an artificially designed DNA monocrystal, built from a short DNA sequence. Using a recently developed frequency domain spectroscopic instrument operating at room temperature with high spectral and spatial resolution, we demonstrated very intense and specific spectral lines from a DNA crystal in general agreement with a computational molecular dynamics (MD) simulation of a short double stranded DNA fragment. The spectroscopic signature measured in the frequency range between 310 and 490 GHz is rich in well resolved and reproducible spectral features thus demonstrating the capability of THz resonance spectroscopy to be used for characterizing custom macromolecules and structures designed and implemented via nanotechnology for a wide variety of application domains. Analysis of MD simulation indicates that intense and narrow vibrational modes with atomic movements perpendicular (transverse) and parallel (longitudinal) to the long DNA axis coexist in dsDNA, with much higher contribution from longitudinal vibrations

An Efficient Method for the Preparative Isolation and Purification of Flavonoids from Leaves of Crataegus pinnatifida by HSCCC and Pre-HPLC.

Science.gov (United States)

Wen, Lei; Lin, Yunliang; Lv, Ruimin; Yan, Huijiao; Yu, Jinqian; Zhao, Hengqiang; Wang, Xiao; Wang, Daijie

2017-05-09

In this work, flavonoid fraction from the leaves of Crataegus pinnatifida was separated into its seven main constituents using a combination of HSCCC coupled with pre-HPLC. In the first step, the total flavonoid extract was subjected to HSCCC with a two-solvent system of chloroform/methanol/water/ n -butanol (4:3:2:1.5, v/v ), yielding four pure compounds, namely (-)-epicatechin ( 1 ), quercetin-3- O -(2,6-di-α-l-rhamnopyranosyl)-β-d-galactopyranoside ( 2 ), 4''- O -glucosylvitexin ( 3 ) and 2''- O -rhamnosylvitexin ( 4 ) as well as a mixture of three further flavonoids. An extrusion mode was used to rapidly separate quercetin-3- O -(2,6-di-α-l-rhamnopyranosyl)-β-d-galactopyranoside with a big K D -value. In the second step, the mixture that resulted from HSCCC was separated by pre-HPLC, resulting in three pure compounds including: vitexin ( 5 ), hyperoside ( 6 ) and isoquercitrin ( 7 ). The purities of the isolated compounds were established to be over 98%, as determined by HPLC. The structures of these seven flavonoids were elucidated by ESI-MS and NMR spectroscopic analyses.

Rotation-induced YORP break-up of small bodies to produce post-main-sequence debris

Science.gov (United States)

Veras, D.; Jacobson, S. A.; Gänsicke, B. T.

2017-09-01

We hypothesize that the in situ break-up of small bodies such as asteroids spun to fission during the giant branch phases of stellar evolution provides an important contribution to the debris orbiting and ultimately polluting white dwarfs. The YORP (Yarkovsky-O'Keefe-Radviesvki-Paddock) effect, which arises from radiation pressure, accelerates the spin rate of asymmetric asteroids, which can eventually shear themselves apart. This pressure is maintained and enhanced around dying stars because the outward push of an asteroid due to stellar mass loss is insignificant compared to the resulting stellar luminosity increase. Consequently, giant star radiation will destroy nearly all bodies with radii in the range 100 m-10 km that survive their parent star's main-sequence lifetime within a distance of about 7 au; smaller bodies are spun apart to their strongest, competent components. This estimate is conservative and would increase for highly asymmetric shapes or incorporation of the inward drag due to giant star stellar wind. The resulting debris field, which could extend to thousands of au, may be perturbed by remnant planetary systems to reproduce the observed dusty and gaseous discs which accompany polluted white dwarfs.

THE ORIGIN OF HVS17, AN UNBOUND MAIN SEQUENCE B STAR AT 50 kpc

Energy Technology Data Exchange (ETDEWEB)

Brown, Warren R.; Geller, Margaret J.; Kenyon, Scott J. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Cohen, Judith G., E-mail: wbrown@cfa.harvard.edu, E-mail: mgeller@cfa.harvard.edu, E-mail: skenyon@cfa.harvard.edu, E-mail: jlc@astro.caltech.edu [Palomar Observatory, Mail Stop 249-17, California Institute of Technology, Pasadena, CA 91125 (United States)

2013-09-20

We analyze Keck Echellette Spectrograph and Imager spectroscopy of HVS17, a B-type star traveling with a Galactic rest frame radial velocity of +445 km s{sup –1} in the outer halo of the Milky Way. HVS17 has the projected rotation of a main sequence B star and is chemically peculiar, with solar iron abundance and sub-solar alpha abundance. Comparing measured T{sub eff} and log g with stellar evolution tracks implies that HVS17 is a 3.91 ± 0.09 M{sub ☉}, 153 ± 9 Myr old star at a Galactocentric distance of r = 48.5 ± 4.6 kpc. The time between its formation and ejection significantly exceeds 10 Myr and thus is difficult to reconcile with any Galactic disk runaway scenario involving massive stars. The observations are consistent, on the other hand, with a hypervelocity star ejection from the Galactic center. We show that Gaia proper motion measurements will easily discriminate between a disk and Galactic center origin, thus allowing us to use HVS17 as a test particle to probe the shape of the Milky Way's dark matter halo.

THE ORIGIN OF HVS17, AN UNBOUND MAIN SEQUENCE B STAR AT 50 kpc

International Nuclear Information System (INIS)

Brown, Warren R.; Geller, Margaret J.; Kenyon, Scott J.; Cohen, Judith G.

2013-01-01

We analyze Keck Echellette Spectrograph and Imager spectroscopy of HVS17, a B-type star traveling with a Galactic rest frame radial velocity of +445 km s –1 in the outer halo of the Milky Way. HVS17 has the projected rotation of a main sequence B star and is chemically peculiar, with solar iron abundance and sub-solar alpha abundance. Comparing measured T eff and log g with stellar evolution tracks implies that HVS17 is a 3.91 ± 0.09 M ☉ , 153 ± 9 Myr old star at a Galactocentric distance of r = 48.5 ± 4.6 kpc. The time between its formation and ejection significantly exceeds 10 Myr and thus is difficult to reconcile with any Galactic disk runaway scenario involving massive stars. The observations are consistent, on the other hand, with a hypervelocity star ejection from the Galactic center. We show that Gaia proper motion measurements will easily discriminate between a disk and Galactic center origin, thus allowing us to use HVS17 as a test particle to probe the shape of the Milky Way's dark matter halo

THE EVOLVED MAIN-SEQUENCE CHANNEL: HST AND LBT OBSERVATIONS OF CSS 120422:111127+571239

Energy Technology Data Exchange (ETDEWEB)

Kennedy, M.; Callanan, P. [Department of Physics, University College Cork, Cork (Ireland); Garnavich, P.; Littlefield, C. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Szkody, P. [Department of Astronomy, University of Washington, Seattle, WA (United States); Pogge, R. [Department of Astronomy, The Ohio State University, 140 W. 18th Avenue, Columbus, OH 43202 (United States)

2015-12-20

The “evolved main-sequence (EMS)” channel is thought to contribute significantly to the population of AM CVn-type systems in the Galaxy, and also to the number of cataclysmic variables (CVs) detected below the period minimum for hydrogen rich systems. CSS 120422:J111127+571239 was discovered by the Catalina Sky Survey in 2012 April. Its period was found to be 56 minutes, well below the minimum, and the optical spectrum is clearly depleted in hydrogen relative to helium, but still has two orders of magnitude more hydrogen than AM CVn stars. Doppler tomography of the Hα line hinted at a spiral structure existing in the disk. Here we present spectroscopy of CSS 120422:J111127+571239 using the Cosmic Origins Spectrograph FUV instrument on the Hubble Space Telescope and using the MODS spectrograph on the Large Binocular Telescope. The UV spectrum shows Si iv, N v, and He ii, but no detectable C iv. The anomalous nitrogen/carbon ratio is seen in a small number of other CVs and confirms a unique binary evolution. We also present and compare the optical spectrum of V418 Ser and advocate that it is also an EMS system.

Blind pre-analysis of the main building complex WWER-440/213 Paks for comparison of analytical and experimental results obtained by explosive testing (task 7a of workplan 95/96)

International Nuclear Information System (INIS)

1999-01-01

Within the research programme on Benchmark studies of seismic analysis of WWER type reactors the blind pre-analysis must be prepared for the main building complex of Paks NPP, based on given excitations derived from explosion tests. The aim of the investigation was to validate different idealization concepts (mathematical models for the idealization of the structures and the soil) as well as investigation procedures (time domain and frequency domain analysis) and finally the software tools by comparing dynamic properties (eigenfrequencies, eigenmodes, modal values) and structural response results (time histories and response spectra). This report contains results of the blind pre-analysis performed by using three dimensional idealization of the main building complex (reactor building, turbine house, galleries) by means of time and frequency domian calculation procedures

Spectroscopic surveys of LAMOST

International Nuclear Information System (INIS)

Zhao Yongheng

2015-01-01

The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST), a new type of reflecting Schmidt telescope, has been designed and produced in China. It marks a breakthrough for large scale spectroscopic survey observation in that both large aperture and wide field of view have been achieved. LAMOST has the highest spectrum acquisition rate, and from October 2011 to June 2014 it has obtained 4.13 million spectra of celestial objects, of which 3.78 million are spectra of stars, with the stellar parameters of 2.20 million stars included. (author)

Correlation between sequence conservation and structural thermodynamics of microRNA precursors from human, mouse, and chicken genomes

Directory of Open Access Journals (Sweden)

Wang Shengqi

2010-10-01

Full Text Available Abstract Background Previous studies have shown that microRNA precursors (pre-miRNAs have considerably more stable secondary structures than other native RNAs (tRNA, rRNA, and mRNA and artificial RNA sequences. However, pre-miRNAs with ultra stable secondary structures have not been investigated. It is not known if there is a tendency in pre-miRNA sequences towards or against ultra stable structures? Furthermore, the relationship between the structural thermodynamic stability of pre-miRNA and their evolution remains unclear. Results We investigated the correlation between pre-miRNA sequence conservation and structural stability as measured by adjusted minimum folding free energies in pre-miRNAs isolated from human, mouse, and chicken. The analysis revealed that conserved and non-conserved pre-miRNA sequences had structures with similar average stabilities. However, the relatively ultra stable and unstable pre-miRNAs were more likely to be non-conserved than pre-miRNAs with moderate stability. Non-conserved pre-miRNAs had more G+C than A+U nucleotides, while conserved pre-miRNAs contained more A+U nucleotides. Notably, the U content of conserved pre-miRNAs was especially higher than that of non-conserved pre-miRNAs. Further investigations showed that conserved and non-conserved pre-miRNAs exhibited different structural element features, even though they had comparable levels of stability. Conclusions We proposed that there is a correlation between structural thermodynamic stability and sequence conservation for pre-miRNAs from human, mouse, and chicken genomes. Our analyses suggested that pre-miRNAs with relatively ultra stable or unstable structures were less favoured by natural selection than those with moderately stable structures. Comparison of nucleotide compositions between non-conserved and conserved pre-miRNAs indicated the importance of U nucleotides in the pre-miRNA evolutionary process. Several characteristic structural elements were

Application of Spectroscopic Methods for Structural Analysis of Chitin and Chitosan

Directory of Open Access Journals (Sweden)

Jolanta Kumirska

2010-04-01

Full Text Available Chitin, the second most important natural polymer in the world, and its N-deacetylated derivative chitosan, have been identified as versatile biopolymers for a broad range of applications in medicine, agriculture and the food industry. Two of the main reasons for this are firstly the unique chemical, physicochemical and biological properties of chitin and chitosan, and secondly the unlimited supply of raw materials for their production. These polymers exhibit widely differing physicochemical properties depending on the chitin source and the conditions of chitosan production. The presence of reactive functional groups as well as the polysaccharide nature of these biopolymers enables them to undergo diverse chemical modifications. A complete chemical and physicochemical characterization of chitin, chitosan and their derivatives is not possible without using spectroscopic techniques. This review focuses on the application of spectroscopic methods for the structural analysis of these compounds.

High-Resolution Photoionization, Photoelectron and Photodissociation Studies. Determination of Accurate Energetic and Spectroscopic Database for Combustion Radicals and Molecules

Energy Technology Data Exchange (ETDEWEB)

Ng, Cheuk-Yiu [Univ. of California, Davis, CA (United States)

2016-04-25

The main goal of this research program was to obtain accurate thermochemical and spectroscopic data, such as ionization energies (IEs), 0 K bond dissociation energies, 0 K heats of formation, and spectroscopic constants for radicals and molecules and their ions of relevance to combustion chemistry. Two unique, generally applicable vacuum ultraviolet (VUV) laser photoion-photoelectron apparatuses have been developed in our group, which have used for high-resolution photoionization, photoelectron, and photodissociation studies for many small molecules of combustion relevance.

Spectroscopic evidence of hippocampal abnormalities in neocortical epilepsy

Science.gov (United States)

Mueller, S. G.; Laxer, K. D.; Cashdollar, N.; Lopez, R. C.; Weiner, M. W.

2009-01-01

Lesional neocortical epilepsy (NE) can be associated with hippocampal sclerosis or hippocampal spectroscopic abnormalities without atrophy (dual pathology). In this study, magnetic resonance spectroscopic imaging (MRSI) was used to determine the frequency of hippocampal damage/dysfunction in NE with and without structural lesion. Sixteen patients with NE [seven temporal NE (NE-T), nine extratemporal (NE-ET)] and 16 controls were studied with a 2D MRSI sequence (Repetition time/echo time (TR/TE) = 1800/135 ms) covering both hippocampi. Seven NE patients had MR visible lesions (NE-Les), nine had normal MRI (NE-no). In each hippocampus, 12 voxels were uniformly selected. In controls, mean (± SD) NAA/(Cr + Cho) values for each voxel were calculated and voxels with NAA/(Cr + Cho) ≤ (mean in controls – 2SD in controls) were defined as ‘pathological’ in patients. Eight of 16 NE patients had at least two ‘pathological’ voxel (mean 2.5, range 2–5) in one hippocampus. Four were NE-Les and four NE-no. Three (43%) NE-T patients, had evidence for hippocampal damage/dysfunction and five (56%) had NE-ET. The ipsilateral hippocampus was affected in six of eight NE patients. Evidence for unilateral hippocampal damage/dysfunction was demonstrated in 50% of the NE patients. The type of NE, i.e. NE-Les or NE-no, NE-T or NE-ET, had no influence on the occurrence of hippocampal damage/dysfunction. PMID:16618342

THE zCOSMOS 10k-BRIGHT SPECTROSCOPIC SAMPLE

International Nuclear Information System (INIS)

Lilly, Simon J.; Maier, Christian; Carollo, Marcella; Caputi, Karina; Le Brun, Vincent; Kneib, Jean-Paul; Le Fevre, Olivier; De la Torre, Sylvain; De Ravel, Loic; Mainieri, Vincenzo; Mignoli, Marco; Zamorani, Gianni; Bardelli, Sandro; Bolzonella, Micol; Coppa, Graziano; Scodeggio, Marco; Contini, Thierry; Renzini, Alvio; Bongiorno, Angela; Cucciati, Olga

2009-01-01

We present spectroscopic redshifts of a large sample of galaxies with I AB -1 , independent of redshift. The reliability of individual redshifts is described by a Confidence Class that has been empirically calibrated through repeat spectroscopic observations of over 600 galaxies. There is very good agreement between spectroscopic and photometric redshifts for the most secure Confidence Classes. For the less secure Confidence Classes, there is a good correspondence between the fraction of objects with a consistent photometric redshift and the spectroscopic repeatability, suggesting that the photometric redshifts can be used to indicate which of the less secure spectroscopic redshifts are likely right and which are probably wrong, and to give an indication of the nature of objects for which we failed to determine a redshift. Using this approach, we can construct a spectroscopic sample that is 99% reliable and which is 88% complete in the sample as a whole, and 95% complete in the redshift range 0.5 < z < 0.8. The luminosity and mass completeness levels of the zCOSMOS-bright sample of galaxies is also discussed.

Single-Shot MR Spectroscopic Imaging with Partial Parallel Imaging

Science.gov (United States)

Posse, Stefan; Otazo, Ricardo; Tsai, Shang-Yueh; Yoshimoto, Akio Ernesto; Lin, Fa-Hsuan

2010-01-01

An MR spectroscopic imaging (MRSI) pulse sequence based on Proton-Echo-Planar-Spectroscopic-Imaging (PEPSI) is introduced that measures 2-dimensional metabolite maps in a single excitation. Echo-planar spatial-spectral encoding was combined with interleaved phase encoding and parallel imaging using SENSE to reconstruct absorption mode spectra. The symmetrical k-space trajectory compensates phase errors due to convolution of spatial and spectral encoding. Single-shot MRSI at short TE was evaluated in phantoms and in vivo on a 3 T whole body scanner equipped with 12-channel array coil. Four-step interleaved phase encoding and 4-fold SENSE acceleration were used to encode a 16×16 spatial matrix with 390 Hz spectral width. Comparison with conventional PEPSI and PEPSI with 4-fold SENSE acceleration demonstrated comparable sensitivity per unit time when taking into account g-factor related noise increases and differences in sampling efficiency. LCModel fitting enabled quantification of Inositol, Choline, Creatine and NAA in vivo with concentration values in the ranges measured with conventional PEPSI and SENSE-accelerated PEPSI. Cramer-Rao lower bounds were comparable to those obtained with conventional SENSE-accelerated PEPSI at the same voxel size and measurement time. This single-shot MRSI method is therefore suitable for applications that require high temporal resolution to monitor temporal dynamics or to reduce sensitivity to tissue movement. PMID:19097245

Neural mechanisms of sequence generation in songbirds

Science.gov (United States)

Langford, Bruce

Animal models in research are useful for studying more complex behavior. For example, motor sequence generation of actions requiring good muscle coordination such as writing with a pen, playing an instrument, or speaking, may involve the interaction of many areas in the brain, each a complex system in itself; thus it can be difficult to determine causal relationships between neural behavior and the behavior being studied. Birdsong, however, provides an excellent model behavior for motor sequence learning, memory, and generation. The song consists of learned sequences of notes that are spectrographically stereotyped over multiple renditions of the song, similar to syllables in human speech. The main areas of the songbird brain involve in singing are known, however, the mechanisms by which these systems store and produce song are not well understood. We used a custom built, head-mounted, miniature motorized microdrive to chronically record the neural firing patterns of identified neurons in HVC, a pre-motor cortical nucleus which has been shown to be important in song timing. These were done in Bengalese finch which generate a song made up of stereotyped notes but variable note sequences. We observed song related bursting in neurons projecting to Area X, a homologue to basal ganglia, and tonic firing in HVC interneurons. Interneuron had firing rate patterns that were consistent over multiple renditions of the same note sequence. We also designed and built a light-weight, low-powered wireless programmable neural stimulator using Bluetooth Low Energy Protocol. It was able to generate perturbations in the song when current pulses were administered to RA, which projects to the brainstem nucleus responsible for syringeal muscle control.

Extended Main-sequence Turn-offs in Intermediate-age Star Clusters: Stellar Rotation Diminishes, but Does Not Eliminate, Age Spreads

Energy Technology Data Exchange (ETDEWEB)

Goudfrooij, Paul; Correnti, Matteo [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Girardi, Léo, E-mail: goudfroo@stsci.edu [Osservatorio Astronomico di Padova—INAF, Vicolo dell’Osservatorio 5, I-35122 Padova (Italy)

2017-09-01

Extended main-sequence turn-off (eMSTO) regions are a common feature in color–magnitude diagrams of young- and intermediate-age star clusters in the Magellanic Clouds. The nature of eMSTOs remains debated in the literature. The currently most popular scenarios are extended star formation activity and ranges of stellar rotation rates. Here we study details of differences in main-sequence turn-off (MSTO) morphology expected from spreads in age versus spreads in rotation rates, using Monte Carlo simulations with the Geneva syclist isochrone models that include the effects of stellar rotation. We confirm a recent finding of Niederhofer et al. that a distribution of stellar rotation velocities yields an MSTO extent that is proportional to the cluster age, as observed. However, we find that stellar rotation yields MSTO crosscut widths that are generally smaller than observed ones at a given age. We compare the simulations with high-quality Hubble Space Telescope data of NGC 1987 and NGC 2249, which are the two only relatively massive star clusters with an age of ∼1 Gyr for which such data is available. We find that the distribution of stars across the eMSTOs of these clusters cannot be explained solely by a distribution of stellar rotation velocities, unless the orientations of rapidly rotating stars are heavily biased toward an equator-on configuration. Under the assumption of random viewing angles, stellar rotation can account for ∼60% and ∼40% of the observed FWHM widths of the eMSTOs of NGC 1987 and NGC 2249, respectively. In contrast, a combination of distributions of stellar rotation velocities and stellar ages fits the observed eMSTO morphologies very well.

Aristotelian pre-Socratics, A glance at Aristotle's Narrative from pre-Socratics

Directory of Open Access Journals (Sweden)

Mehdi Qavam Safari

2015-02-01

Full Text Available In this article, it's tried to study Aristotle's narrative of  pre-Socratics on the base of Aristotle's texts and mainly using  metaphysics, physics, genesis and decadence books. It is also tried to show how Aristotle has interpreted all the pre-Socratics in one way and on the base of his own philosophy framework. He interprets pre-Socratic Arche as an element that means comprehensive matter which is nothing itself, but everything is combination of it and even considers that as substance and the other things as accident. He interprets the distinction of Arche and other things on the basis of this contrast in his philosophy. Aristotle, also analyzes pre-Socratics' viewpoint to change on the base of his distinction among change, genesis and corruption. All these cases show that Aristotle has interpreted the pre-Socratics on the basis of his thought, as Aristotelians. On this basis, since Aristotle's thoughts are the first and the most important sources of pre-Socratic philosophy, Aristotle's role should be considered in studies.

The protein circular dichroism data bank, a Web-based site for access to circular dichroism spectroscopic data.

Science.gov (United States)

Whitmore, Lee; Woollett, Benjamin; Miles, Andrew J; Janes, Robert W; Wallace, B A

2010-10-13

The Protein Circular Dichroism Data Bank (PCDDB) is a newly released resource for structural biology. It is a web-accessible (http://pcddb.cryst.bbk.ac.uk) data bank for circular dichroism (CD) and synchrotron radiation circular dichroism (SRCD) spectra and their associated experimental and secondary metadata, with links to protein sequence and structure data banks. It is designed to provide a public repository for CD spectroscopic data on macromolecules, to parallel the Protein Data Bank (PDB) for crystallographic, electron microscopic, and nuclear magnetic resonance spectroscopic data. Similarly to the PDB, it includes validation checking procedures to ensure good practice and the integrity of the deposited data. This paper reports on the first public release of the PCDDB, which provides access to spectral data that comprise standard reference datasets. Copyright © 2010 Elsevier Ltd. All rights reserved.

The Star Formation Main Sequence in the Hubble Space Telescope Frontier Fields

Science.gov (United States)

Santini, Paola; Fontana, Adriano; Castellano, Marco; Di Criscienzo, Marcella; Merlin, Emiliano; Amorin, Ricardo; Cullen, Fergus; Daddi, Emanuele; Dickinson, Mark; Dunlop, James S.; Grazian, Andrea; Lamastra, Alessandra; McLure, Ross J.; Michałowski, Michał. J.; Pentericci, Laura; Shu, Xinwen

2017-09-01

We investigate the relation between star formation rate (SFR) and stellar mass (M), I.e., the main sequence (MS) relation of star-forming galaxies, at 1.3≤slant zFrontier Fields, on the basis of rest-frame UV observations. Gravitational lensing combined with deep HST observations allows us to extend the analysis of the MS down to {log} M/{M}⊙ ˜ 7.5 at z≲ 4 and {log} M/{M}⊙ ˜ 8 at higher redshifts, a factor of ˜10 below most previous results. We perform an accurate simulation to take into account the effect of observational uncertainties and correct for the Eddington bias. This step allows us to reliably measure the MS and in particular its slope. While the normalization increases with redshift, we fit an unevolving and approximately linear slope. We nicely extend to lower masses the results of brighter surveys. Thanks to the large dynamic range in mass and by making use of the simulation, we analyzed any possible mass dependence of the dispersion around the MS. We find tentative evidence that the scatter decreases with increasing mass, suggesting a larger variety of star formation histories in low-mass galaxies. This trend agrees with theoretical predictions and is explained as either a consequence of the smaller number of progenitors of low-mass galaxies in a hierarchical scenario and/or of the efficient but intermittent stellar feedback processes in low-mass halos. Finally, we observe an increase in the SFR per unit stellar mass with redshift milder than predicted by theoretical models, implying a still incomplete understanding of the processes responsible for galaxy growth.

Sensitivity-encoded (SENSE) proton echo-planar spectroscopic imaging (PEPSI) in the human brain.

Science.gov (United States)

Lin, Fa-Hsuan; Tsai, Shang-Yueh; Otazo, Ricardo; Caprihan, Arvind; Wald, Lawrence L; Belliveau, John W; Posse, Stefan

2007-02-01

Magnetic resonance spectroscopic imaging (MRSI) provides spatially resolved metabolite information that is invaluable for both neuroscience studies and clinical applications. However, lengthy data acquisition times, which are a result of time-consuming phase encoding, represent a major challenge for MRSI. Fast MRSI pulse sequences that use echo-planar readout gradients, such as proton echo-planar spectroscopic imaging (PEPSI), are capable of fast spectral-spatial encoding and thus enable acceleration of image acquisition times. Combining PEPSI with recent advances in parallel MRI utilizing RF coil arrays can further accelerate MRSI data acquisition. Here we investigate the feasibility of ultrafast spectroscopic imaging at high field (3T and 4T) by combining PEPSI with sensitivity-encoded (SENSE) MRI using eight-channel head coil arrays. We show that the acquisition of single-average SENSE-PEPSI data at a short TE (15 ms) can be accelerated to 32 s or less, depending on the field strength, to obtain metabolic images of choline (Cho), creatine (Cre), N-acetyl-aspartate (NAA), and J-coupled metabolites (e.g., glutamate (Glu) and inositol (Ino)) with acceptable spectral quality and localization. The experimentally measured reductions in signal-to-noise ratio (SNR) and Cramer-Rao lower bounds (CRLBs) of metabolite resonances were well explained by both the g-factor and reduced measurement times. Thus, this technology is a promising means of reducing the scan times of 3D acquisitions and time-resolved 2D measurements. Copyright (c) 2007 Wiley-Liss, Inc.

INTERFEROMETRIC EVIDENCE FOR RESOLVED WARM DUST IN THE DQ TAU SYSTEM

International Nuclear Information System (INIS)

Boden, Andrew F.; Sargent, Anneila I.; Carpenter, John M.; Akeson, Rachel L.; Ciardi, David R.; Bary, Jeffrey S.; Skrutskie, Michael F.

2009-01-01

We report on near-infrared (IR) interferometric observations of the double-lined pre-main sequence binary system DQ Tau. We model these data with a visual orbit for DQ Tau supported by the spectroscopic orbit and analysis of Mathieu et al. Further, DQ Tau exhibits significant near-IR excess; modeling our data requires inclusion of near-IR light from an 'excess' source. Remarkably, the excess source is resolved in our data, similar in scale to the binary itself (∼0.2 AU at apastron), rather than the larger circumbinary disk (∼0.4 AU radius). Our observations support the Mathieu et al. and Carr et al. inference of significant warm material near the DQ Tau binary.

Prior-knowledge Fitting of Accelerated Five-dimensional Echo Planar J-resolved Spectroscopic Imaging: Effect of Nonlinear Reconstruction on Quantitation.

Science.gov (United States)

Iqbal, Zohaib; Wilson, Neil E; Thomas, M Albert

2017-07-24

1 H Magnetic Resonance Spectroscopic imaging (SI) is a powerful tool capable of investigating metabolism in vivo from mul- tiple regions. However, SI techniques are time consuming, and are therefore difficult to implement clinically. By applying non-uniform sampling (NUS) and compressed sensing (CS) reconstruction, it is possible to accelerate these scans while re- taining key spectral information. One recently developed method that utilizes this type of acceleration is the five-dimensional echo planar J-resolved spectroscopic imaging (5D EP-JRESI) sequence, which is capable of obtaining two-dimensional (2D) spectra from three spatial dimensions. The prior-knowledge fitting (ProFit) algorithm is typically used to quantify 2D spectra in vivo, however the effects of NUS and CS reconstruction on the quantitation results are unknown. This study utilized a simulated brain phantom to investigate the errors introduced through the acceleration methods. Errors (normalized root mean square error >15%) were found between metabolite concentrations after twelve-fold acceleration for several low concentra- tion (OGM) human brain matter were quantified in vivo using the 5D EP-JRESI sequence with eight-fold acceleration.

Spectroscopic investigation on interaction of toluidine blue/ AOT/ γ-cyclodextrin ternary system

Energy Technology Data Exchange (ETDEWEB)

Dasmandal, Somnath; Bhattacharyya, Debabrata; Rudra, Suparna; Patel, Biman Kumar; Mahapatra, Ambikesh, E-mail: amahapatra@chemistry.jdvu.ac.in

2016-11-15

Interaction of toluidine blue (TB), a biologically potent cationic phenothiazinium dye, with anionic surfactant, sodium bis(2-ethylhexyl) sulfosuccinate (AOT) have been thoroughly studied employing absorption and emission spectroscopy. A completely distinct spectral behavior of TB has been observed corresponding to pre-micellar and post-micellar region of AOT. Steady-state fluorescence anisotropy measurement has been carefully undertaken to rationalize the spectroscopic results. Effect of γ-cyclodextrin (γ-CD) on the spectral properties of TB has also been encountered for understanding of binding interaction between them. Molecular docking study has been accomplished to enlighten the probable orientation of TB inside the γ-CD core. Here particular interest has been focused on a mixed system, composed of AOT pre-micelles and γ-CD. A remarkable diminution of both absorption and emission intensities of TB has been observed in AOT pre-micelle with a simultaneous colorimetric change of TB solution from dark blue to lavender, and subsequent addition of γ-CD results in enhancement of intensities with dramatic reversal of the lavender colored solution to the original dark blue color. The emission characteristics of TB in the presence of AOT and γ-CD may prove as promising for an ‘IMPLICATION’ logic gate which may perform a significant role in the field of molecular electronics.

Phylogenetic reconstruction of Bantu kinship challenges Main Sequence Theory of human social evolution.

Science.gov (United States)

Opie, Christopher; Shultz, Susanne; Atkinson, Quentin D; Currie, Thomas; Mace, Ruth

2014-12-09

Kinship provides the fundamental structure of human society: descent determines the inheritance pattern between generations, whereas residence rules govern the location a couple moves to after they marry. In turn, descent and residence patterns determine other key relationships such as alliance, trade, and marriage partners. Hunter-gatherer kinship patterns are viewed as flexible, whereas agricultural societies are thought to have developed much more stable kinship patterns as they expanded during the Holocene. Among the Bantu farmers of sub-Saharan Africa, the ancestral kinship patterns present at the beginning of the expansion are hotly contested, with some arguing for matrilineal and matrilocal patterns, whereas others maintain that any kind of lineality or sex-biased dispersal only emerged much later. Here, we use Bayesian phylogenetic methods to uncover the history of Bantu kinship patterns and trace the interplay between descent and residence systems. The results suggest a number of switches in both descent and residence patterns as Bantu farming spread, but that the first Bantu populations were patrilocal with patrilineal descent. Across the phylogeny, a change in descent triggered a switch away from patrifocal kinship, whereas a change in residence triggered a switch back from matrifocal kinship. These results challenge "Main Sequence Theory," which maintains that changes in residence rules precede change in other social structures. We also indicate the trajectory of kinship change, shedding new light on how this fundamental structure of society developed as farming spread across the globe during the Neolithic.

Phosphorus-31 spectroscopic imaging of the human liver

International Nuclear Information System (INIS)

Biran, M.; Raffard, G.; Canioni, P.; Kien, P.

1993-01-01

During the last decade, progresses in the field of nuclear magnetic resonance spectroscopy (M.R.S.), have allowed the metabolic studies of complex biological systems. Since the coming out of whole body magnets, clinical applications are possible; they utilize magnetic field gradients coupled with selective pulse sequences. Study of the phosphorylated metabolism of human liver can be performed with sequences as ISIS, FROGS or 1D-CSI. But they present some disadvantages (for instance contamination by phosphocreatine from muscle). In the present work, we have studied the human liver in vivo by 31 P spectroscopic imaging. Several spectra could be acquired with only one acquisition. This study has needed the building of radiofrequency coils (surface coils), specially designed for liver observation (15 cm diameter 31 P coil and 19 cm diameter proton coil, both transmitter and receiver coils). Preliminary studies have been done on a phantom followed by in vivo measurements on healthy subject livers. We have obtained localized 31 P N.M.R. spectra corresponding to different voxels within the hepatic tissue. The conditions of acquisition of spectra and the problems related to the saturation of phosphorylated metabolite signals (in particular phosphodiesters) are discussed. (author). 5 figs., 15 refs

Spectroscopic analysis of optoelectronic semiconductors

CERN Document Server

Jimenez, Juan

2016-01-01

This book deals with standard spectroscopic techniques which can be used to analyze semiconductor samples or devices, in both, bulk, micrometer and submicrometer scale. The book aims helping experimental physicists and engineers to choose the right analytical spectroscopic technique in order to get specific information about their specific demands. For this purpose, the techniques including technical details such as apparatus and probed sample region are described. More important, also the expected outcome from experiments is provided. This involves also the link to theory, that is not subject of this book, and the link to current experimental results in the literature which are presented in a review-like style. Many special spectroscopic techniques are introduced and their relationship to the standard techniques is revealed. Thus the book works also as a type of guide or reference book for people researching in optical spectroscopy of semiconductors.

Challenging pre-galilean misconceptions through alternative visualizations

OpenAIRE

Blanquet, Estelle; Picholle, Eric

2011-01-01

International audience; While duly Copernican, a significant part of primary school teachers-in-training fail to see the point of the (Galilean) principle of relativity. Two inquiry based teaching sequences involving the notion of reference frame were designed to challenge the students' robust pre-Galilean misconceptions, without mathematical requirements. The first sequence makes use of an artist view ("Framed Earth", by Manchu, 1989) and literary representations of the Earth as seen from a ...

Spectroscopic studies with the use of deep-inelastic heavy-ion reactions

International Nuclear Information System (INIS)

Broda, R

2006-01-01

Gamma spectroscopic studies exploiting deep-inelastic heavy-ion reactions in thick target experiments are reviewed. The description of physical motivation, history of early experiments, analysis of the N/Z equilibration process as well as the outline of the experimental method and data analysis are followed by the presentation of main results obtained in various regions of the nuclide chart. Brief comments on thin target spectroscopy experiments involving fragment detection and future outlook are summarized. (topical review)

Abundance analysis of SDSS J134338.67+484426.6; an extremely metal-poor star from the MARVELS pre-survey

Science.gov (United States)

Susmitha Rani, A.; Sivarani, T.; Beers, T. C.; Fleming, S.; Mahadevan, S.; Ge, J.

2016-05-01

We present an elemental-abundance analysis of an extremely metal-poor (EMP; [Fe/H] <-3.0) star, SDSS J134338.67+484426.6, identified during the course of the Multi-object Apache Point Observatory Radial Velocity Exoplanet Large-area Survey spectroscopic pre-survey of some 20 000 stars to identify suitable candidates for exoplanet searches. This star, with an apparent magnitude V = 12.14, is the lowest metallicity star found in the pre-survey, and is one of only ˜20 known EMP stars that are this bright or brighter. Our high-resolution spectroscopic analysis shows that this star is a subgiant with [Fe/H] = -3.42, having `normal' carbon and no enhancement of neutron-capture abundances. Strontium is underabundant, [Sr/Fe] = -0.47, but the derived lower limit on [Sr/Ba] indicates that Sr is likely enhanced relative to Ba. This star belongs to the sparsely populated class of α-poor EMP stars that exhibit low ratios of [Mg/Fe], [Si/Fe], and [Ca/Fe] compared to typical halo stars at similar metallicity. The observed variations in radial velocity from several epochs of (low- and high-resolution) spectroscopic follow-up indicate that SDSS J134338.67+484426.6 is a possible long-period binary. We also discuss the abundance trends in EMP stars for r-process elements, and compare with other magnesium-poor stars.

INSPIRE Project (IoNospheric Sounding for Pre-seismic anomalies Identification REsearch): Main Results and Future Prospects

Science.gov (United States)

Pulinets, S. A.; Andrzej, K.; Hernandez-Pajares, M.; Cherniak, I.; Zakharenkova, I.; Rothkaehl, H.; Davidenko, D.

2017-12-01

The INSPIRE project is dedicated to the study of physical processes and their effects in ionosphere which could be determined as earthquake precursors together with detailed description of the methodology of ionospheric pre-seismic anomalies definition. It was initiated by ESA and carried out by international consortium. The physical mechanisms of the ionospheric pre-seismic anomalies generation from ground to the ionosphere altitudes were formulated within framework of the Lithosphere-Atmosphere-Ionosphere-Magnetosphere Coupling (LAIMC) model (Pulinets et al., 2015). The general algorithm for the identification of the ionospheric precursors was formalized which also takes into account the external Space Weather factors able to generate the false alarms. Importance of the special stable pattern called the "precursor mask" was highlighted which is based on self-similarity of pre-seismic ionospheric variations. The role of expert decision in pre-seismic anomalies interpretation for generation of seismic warning is important as well. The algorithm performance of the LAIMC seismo-ionospheric effect detection module has been demonstrated using the L'Aquila 2009 earthquake as a case study. The results of INSPIRE project have demonstrated that the ionospheric anomalies registered before the strong earthquakes could be used as reliable precursors. The detailed classification of the pre-seismic anomalies was presented in different regions of the ionosphere and signatures of the pre-seismic anomalies as detected by ground and satellite based instruments were described what clarified methodology of the precursor's identification from ionospheric multi-instrumental measurements. Configuration for the dedicated multi-observation experiment and satellite payload was proposed for the future implementation of the INSPIRE project results. In this regard the multi-instrument set can be divided by two groups: space equipment and ground-based support, which could be used for real

Development of laser spectroscopic technology in nuclear industry

International Nuclear Information System (INIS)

Lee, Jong Min; Cha, Byung Heon; Kim, Seong Ho; Cha, Hyung Ki; Lim, Chang Hwan; Song, Kye Seok; Kim, Jung Bok; Rho, Si Pyo; Han, Jae Min; Jeong, Do Yung; Lee, Jong Hoon; Choi, Hwa Lim; Yoo, Byung Duk; Choi, An Sung; Lee, Byung Chul; Kim, Chul Jung

1992-05-01

The goal of this project is to carry out the fundamental researches for the selective photoionization process of heavy atoms as well as the development of experimentally related instruments. Main research results carried out in this year are (1) multi-step photoionization spectroscopy of Hg atom by 3-color 3-step ionization scheme, (2) selective photoionization using polarization spectroscopy, (3) design and construction of ion separator chamber, and (4) theoretical study for spectroscopic parameters of mercury. This technology can be applied to several area of nuclear industry such as the utilization of radioactive waste, the development of new materials, high sensitive analysis of heavy atomic elements. (Author)

Flashback resistant pre-mixer assembly

Science.gov (United States)

Laster, Walter R [Oviedo, FL; Gambacorta, Domenico [Oviedo, FL

2012-02-14

A pre-mixer assembly associated with a fuel supply system for mixing of air and fuel upstream from a main combustion zone in a gas turbine engine. The pre-mixer assembly includes a swirler assembly disposed about a fuel injector of the fuel supply system and a pre-mixer transition member. The swirler assembly includes a forward end defining an air inlet and an opposed aft end. The pre-mixer transition member has a forward end affixed to the aft end of the swirler assembly and an opposed aft end defining an outlet of the pre-mixer assembly. The aft end of the pre-mixer transition member is spaced from a base plate such that a gap is formed between the aft end of the pre-mixer transition member and the base plate for permitting a flow of purge air therethrough to increase a velocity of the air/fuel mixture exiting the pre-mixer assembly.

VizieR Online Data Catalog: Pisa pre-main sequence tracks and isochrones (Tognelli+, 2011)

Science.gov (United States)

Tognelli, E.; Prada Moroni, P. G.; Degl'Innocenti, S.

2011-07-01

Evolutionary tracks and Isochrones in the log L vs log Te plane, for the following chemical compositions: Z Y Y Y 2.00E-04 0.230 0.249 0.250 1.00E-03 0.232 0.251 0.254 2.00E-03 0.234 0.253 0.259 3.00E-03 0.236 0.254 0.263 4.00E-03 0.238 0.256 0.269 5.00E-03 0.240 0.258 0.273 6.00E-03 0.242 0.260 0.279 7.00E-03 0.244 0.262 0.283 8.00E-03 0.246 0.265 0.289 9.00E-03 0.248 0.267 0.294 1.00E-02 0.250 0.268 0.299 1.25E-02 0.255 0.274 0.311 1.50E-02 0.260 0.278 0.323 1.75E-02 0.265 0.284 0.336 2.00E-02 0.270 0.288 0.349 2.25E-02 0.275 0.294 0.361 2.50E-02 0.280 0.299 0.374 2.75E-02 0.285 0.304 0.386 3.00E-02 0.290 0.308 0.398 Each model is calculated with an initial Deuterium abundance XD=4.0E-05. For Z>=0.008, models with XD=2.0E-05 are available, too. Each model is calculated with three different values of the mixing length parameter alpha = 1.20, 1.68 (solar calibrated), 1.90. There is also a dataset for our Standard Solar Model parameters (Z=0.01377, Y=0.2533, alpha=1.68, XD=2.0E-05). (5 data files).

Extreme value statistics for two-dimensional convective penetration in a pre-main sequence star

Science.gov (United States)

Pratt, J.; Baraffe, I.; Goffrey, T.; Constantino, T.; Viallet, M.; Popov, M. V.; Walder, R.; Folini, D.

2017-08-01

Context. In the interior of stars, a convectively unstable zone typically borders a zone that is stable to convection. Convective motions can penetrate the boundary between these zones, creating a layer characterized by intermittent convective mixing, and gradual erosion of the density and temperature stratification. Aims: We examine a penetration layer formed between a central radiative zone and a large convection zone in the deep interior of a young low-mass star. Using the Multidimensional Stellar Implicit Code (MUSIC) to simulate two-dimensional compressible stellar convection in a spherical geometry over long times, we produce statistics that characterize the extent and impact of convective penetration in this layer. Methods: We apply extreme value theory to the maximal extent of convective penetration at any time. We compare statistical results from simulations which treat non-local convection, throughout a large portion of the stellar radius, with simulations designed to treat local convection in a small region surrounding the penetration layer. For each of these situations, we compare simulations of different resolution, which have different velocity magnitudes. We also compare statistical results between simulations that radiate energy at a constant rate to those that allow energy to radiate from the stellar surface according to the local surface temperature. Results: Based on the frequency and depth of penetrating convective structures, we observe two distinct layers that form between the convection zone and the stable radiative zone. We show that the probability density function of the maximal depth of convective penetration at any time corresponds closely in space with the radial position where internal waves are excited. We find that the maximal penetration depth can be modeled by a Weibull distribution with a small shape parameter. Using these results, and building on established scalings for diffusion enhanced by large-scale convective motions, we propose a new form for the diffusion coefficient that may be used for one-dimensional stellar evolution calculations in the large Péclet number regime. These results should contribute to the 321D link.

Intrinsic folding of small peptide chains: spectroscopic evidence for the formation of beta-turns in the gas phase.

Science.gov (United States)

Chin, Wutharath; Dognon, Jean-Pierre; Piuzzi, François; Tardivel, Benjamin; Dimicoli, Iliana; Mons, Michel

2005-01-19

Laser desorption of model peptides coupled to laser spectroscopic techniques enables the gas-phase observation of genuine secondary structures of biology. Spectroscopic evidence for the formation of beta-turns in gas-phase peptide chains containing glycine and phenylalanine residues establishes the intrinsic stability of these forms and their ability to compete with other stable structures. The precise characterization of local minima on the potential energy surface from IR spectroscopy constitutes an acute assessment for the state-of-the-art quantum mechanical calculations also presented. The observation of different types of beta-turns depending upon the residue order within the sequence is found to be consistent with the residue propensities in beta-turns of proteins, which suggests that the prevalence of glycine in type II and II' turns stems essentially from an energetic origin, already at play under isolated conditions.

Single-shot magnetic resonance spectroscopic imaging with partial parallel imaging.

Science.gov (United States)

Posse, Stefan; Otazo, Ricardo; Tsai, Shang-Yueh; Yoshimoto, Akio Ernesto; Lin, Fa-Hsuan

2009-03-01

A magnetic resonance spectroscopic imaging (MRSI) pulse sequence based on proton-echo-planar-spectroscopic-imaging (PEPSI) is introduced that measures two-dimensional metabolite maps in a single excitation. Echo-planar spatial-spectral encoding was combined with interleaved phase encoding and parallel imaging using SENSE to reconstruct absorption mode spectra. The symmetrical k-space trajectory compensates phase errors due to convolution of spatial and spectral encoding. Single-shot MRSI at short TE was evaluated in phantoms and in vivo on a 3-T whole-body scanner equipped with a 12-channel array coil. Four-step interleaved phase encoding and fourfold SENSE acceleration were used to encode a 16 x 16 spatial matrix with a 390-Hz spectral width. Comparison with conventional PEPSI and PEPSI with fourfold SENSE acceleration demonstrated comparable sensitivity per unit time when taking into account g-factor-related noise increases and differences in sampling efficiency. LCModel fitting enabled quantification of inositol, choline, creatine, and N-acetyl-aspartate (NAA) in vivo with concentration values in the ranges measured with conventional PEPSI and SENSE-accelerated PEPSI. Cramer-Rao lower bounds were comparable to those obtained with conventional SENSE-accelerated PEPSI at the same voxel size and measurement time. This single-shot MRSI method is therefore suitable for applications that require high temporal resolution to monitor temporal dynamics or to reduce sensitivity to tissue movement.

The Solar Neighborhood. XLI. A Study of the Wide Main Sequence for M Dwarfs—Long-term Photometric Variability

Energy Technology Data Exchange (ETDEWEB)

Clements, Tiffany D.; Jao, Wei-Chun; Silverstein, Michele L. [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303 (United States); Henry, Todd J.; Hosey, Altonio D. [RECONS Institute, Chambersburg, PA 17201 (United States); Winters, Jennifer G. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Dieterich, Sergio B. [Carnegie Institution for Science, Washington, DC 20015 (United States); Riedel, Adric R., E-mail: pewett@astro.gsu.edu, E-mail: jao@astro.gsu.edu, E-mail: silverstein@astro.gsu.edu, E-mail: toddhenry28@gmail.com, E-mail: altoniohosey@gmail.com, E-mail: jennifer.winters@cfa.harvard.edu, E-mail: sdieterich@carnegiescience.edu, E-mail: adric.riedel@gmail.com [Space Telescope Science Institute, Baltimore, MD 21218 (United States)

2017-09-01

We report findings from a long-term photometric variability study of M dwarfs carried out at the SMARTS 0.9 m telescope at the Cerro Tololo Inter-American Observatory. As part of a multi-faceted effort to investigate the range of luminosities of M dwarfs of a given color on the Hertzsprung–Russell Diagram, 76 M dwarfs have been observed for 3–17 years in the Johnson–Kron–Cousins V band. We find that stars elevated above the center of the main sequence distribution tend to have higher levels of variability, likely caused by magnetic activity, than their fainter counterparts below the center. This study provides insight into how the long-term magnetic activity of these stars may be affecting their sizes, luminosities, and thus positions on the H-R Diagram.

Sequence dependent DNA conformations: Raman spectroscopic studies and a model of action of restriction enzymes

International Nuclear Information System (INIS)

Nishimura, Y.

1985-01-01

Raman spectra have been examined to clarify the polymorphic forms of DNA, A, B, and Z forms. From an analysis the authors found that the guanine ring breathing vibration is sensitive to its local conformation. Examination of nine crystals of guanosine residues in which the local conformations are well established revealed that a guanosine residue with a C3'endo-anti gives a strong line at 666+-2 cm/sup -1/, O4'endo-anti at 682 cm/sup -1/, C1'exo-anti at 673 cm/sup -1/, C2'endo-anti at 677 cm/sup -1/ and syn-forms around 625 cm/sup -1/. Using this characteristic line, they were able to obtain the local conformations of guanosine moieties in poly(dG-dC). Such a sequence derived variation is suggested to be recognized by sequence specific proteins such as restriction enzymes. The authors found a correlation between sequence dependent DNA conformation and a mode of action of restriction enzymes. The cutting mode of restriction enzymes is classified into three groups. The classification of whether the products have blunt ends, two-base-long cohesive ends, or four-base-long cohesive ends depends primarily on the substrate, not on the enzyme. It is suggested that sequence dependent DNA conformation causes such a classification by the use of the Calladine-Dickerson analysis. In the recognition of restriction enzymes, the methyl group in a certain sequence is considered to play an important role by changing the local conformation of DNA

Raman Spectroscopic Studies of Methane Gas Hydrates

DEFF Research Database (Denmark)

Hansen, Susanne Brunsgaard; Berg, Rolf W.

2009-01-01

A brief review of the Raman spectroscopic studies of methane gas hydrates is given, supported by some new measurements done in our laboratory.......A brief review of the Raman spectroscopic studies of methane gas hydrates is given, supported by some new measurements done in our laboratory....

Stress rotations due to the M6.5 foreshock and M7.3 main shock in the 2016 Kumamoto, SW Japan, earthquake sequence

Science.gov (United States)

Yoshida, Keisuke; Hasegawa, Akira; Saito, Tatsuhiko; Asano, Youichi; Tanaka, Sachiko; Sawazaki, Kaoru; Urata, Yumi; Fukuyama, Eiichi

2016-10-01

A shallow M7.3 event with a M6.5 foreshock occurred along the Futagawa-Hinagu fault zone in Kyushu, SW Japan. We investigated the spatiotemporal variation of the stress orientations in and around the source area of this 2016 Kumamoto earthquake sequence by inverting 1218 focal mechanisms. The results show that the σ3 axis in the vicinity of the fault plane significantly rotated counterclockwise after the M6.5 foreshock and rotated clockwise after the M7.3 main shock in the Hinagu fault segment. This observation indicates that a significant portion of the shear stress was released both by the M6.5 foreshock and M7.3 main shock. It is estimated that the stress release by the M6.5 foreshock occurred in the shallower part of the Hinagu fault segment, which brought the stress concentration in its deeper part. This might have caused the M7.3 main shock rupture mainly along the deeper part of the Hinagu fault segment after 28 h.

Multi-pass spectroscopic ellipsometry

International Nuclear Information System (INIS)

Stehle, Jean-Louis; Samartzis, Peter C.; Stamataki, Katerina; Piel, Jean-Philippe; Katsoprinakis, George E.; Papadakis, Vassilis; Schimowski, Xavier; Rakitzis, T. Peter; Loppinet, Benoit

2014-01-01

Spectroscopic ellipsometry is an established technique, particularly useful for thickness measurements of thin films. It measures polarization rotation after a single reflection of a beam of light on the measured substrate at a given incidence angle. In this paper, we report the development of multi-pass spectroscopic ellipsometry where the light beam reflects multiple times on the sample. We have investigated both theoretically and experimentally the effect of sample reflectivity, number of reflections (passes), angles of incidence and detector dynamic range on ellipsometric observables tanΨ and cosΔ. The multiple pass approach provides increased sensitivity to small changes in Ψ and Δ, opening the way for single measurement determination of optical thickness T, refractive index n and absorption coefficient k of thin films, a significant improvement over the existing techniques. Based on our results, we discuss the strengths, the weaknesses and possible applications of this technique. - Highlights: • We present multi-pass spectroscopic ellipsometry (MPSE), a multi-pass approach to ellipsometry. • Different detectors, samples, angles of incidence and number of passes were tested. • N passes improve polarization ratio sensitivity to the power of N. • N reflections improve phase shift sensitivity by a factor of N. • MPSE can significantly improve thickness measurements in thin films

Blind pre-analysis of the main building complex WWER-1000 Kozloduy. Comparison of analytical and experimental results obtained by explosive testing (task 8a of workplan 96/97)

International Nuclear Information System (INIS)

Krutzik, N.J.

1999-01-01

In accordance with the 96/97 workplan of the Research Programme on 'Benchmark Studies for Seismic Analysis and Testing of WWER-Type Nuclear Power Plants', blind pre analyses were prepared for the main building complex of the WWER-1000 based on given excitations derived from explosive tests. The investigations were performed by several institutions based on various mathematical models and procedures for consideration of soil-structure interaction effects, but on the same explosive test input data recently obtained. The methods of calculation and software tools used will also be different. The aim of this investigation is to validate different idealization concepts (mathematical models for the idealization of the structures and the soil) as well as investigation procedures (time domain and frequency domain analysis) and finally the software tools by comparing structural response results (time histories and response spectra). This report contains the results of the blind pre analysis performed by Siemens using an equivalent beam model of the main building of the WWER 1000. The calculations were performed by means of a frequency domain calculation

Grain temperature, radiation pressure and electric potential in the vicinity of main sequence and white dwarf stars

Energy Technology Data Exchange (ETDEWEB)

Leiknes, J.; Havnes, O. (University of Tromso, Auroral Observatory (Norway))

1984-08-01

We present results of calculations of the grain physical parameters temperature, lifetime against evaporation, radiation pressure and electric potential for spherical grains near main sequence stars, hydrogen type (DA) white dwarfs and helium type (DB) white dwarfs. These parameters are essential in determining the behaviour of grains near such stars. The grain temperature as a function of stellar distance is calculated for grains of sizes 0.1 and 1 ..mu.. (micron) for grain materials of silicate (obsidian), iron and graphite. The lifetime due to thermal evaporation as a function of grain temperature of these materials is also given. The radiation pressure is given for grain sizes from 0.01 to 10 ..mu.. for the same three grain materials. Grain potentials have been calculated as functions of stellar distance for one photoelectron high yield material (silicate) and one low yield material (graphite) for grains of radius 0.1 ..mu.. embedded in a thermal plasma of temperature T = 10/sup 4/ K.

THE APOKASC CATALOG: AN ASTEROSEISMIC AND SPECTROSCOPIC JOINT SURVEY OF TARGETS IN THE KEPLER FIELDS

Energy Technology Data Exchange (ETDEWEB)

Pinsonneault, Marc H.; Epstein, Courtney; Johnson, Jennifer A. [Department of Astronomy, The Ohio State University, Columbus, OH 43210 (United States); Elsworth, Yvonne; Chaplin, William J. [University of Birmingham, School of Physics and Astronomy, Edgbaston, Birmingham B15 2TT (United Kingdom); Hekker, Saskia; Silva Aguirre, Victor; Stello, Dennis [Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Mészáros, Sz. [Astronomy Department, Indiana University, Bloomington, IN 47405 (United States); García, Rafael A.; Beck, Paul [Laboratoire AIM, CEA/DSM-CNRS—Université Denis Diderot-IRFU/SAp, F-91191 Gif-sur-Yvette Cedex (France); Holtzman, Jon [Department of Astronomy, MSC 4500, New Mexico State University, P.O. Box 30001, Las Cruces, NM 88003 (United States); Mathur, Savita [Space Science Institute, 4750 Walnut street, Suite 205, Boulder, CO 80301 (United States); García Pérez, Ana [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States); Girardi, Léo [Osservatorio Astronomico di Padova—INAF, Vicolo dell' Osservatorio 5, I-35122 Padova (Italy); Basu, Sarbani [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States); Shetrone, Matthew [University of Texas at Austin, McDonald Observatory, 32 Fowlkes Road, TX 79734-3005 (United States); Allende Prieto, Carlos [Instituto de Astrofsica de Canarias (IAC), C/Va Lactea, s/n, E-38200 La Laguna, Tenerife (Spain); An, Deokkeun [Department of Science Education, Ewha Womans University, Seoul (Korea, Republic of); Beers, Timothy C., E-mail: pinsonneault.1@osu.edu [Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46656 (United States); and others

2015-01-01

We present the first APOKASC catalog of spectroscopic and asteroseismic properties of 1916 red giants observed in the Kepler fields. The spectroscopic parameters provided from the Apache Point Observatory Galactic Evolution Experiment project are complemented with asteroseismic surface gravities, masses, radii, and mean densities determined by members of the Kepler Asteroseismology Science Consortium. We assess both random and systematic sources of error and include a discussion of sample selection for giants in the Kepler fields. Total uncertainties in the main catalog properties are of the order of 80 K in T {sub eff}, 0.06 dex in [M/H], 0.014 dex in log g, and 12% and 5% in mass and radius, respectively; these reflect a combination of systematic and random errors. Asteroseismic surface gravities are substantially more precise and accurate than spectroscopic ones, and we find good agreement between their mean values and the calibrated spectroscopic surface gravities. There are, however, systematic underlying trends with T {sub eff} and log g. Our effective temperature scale is between 0 and 200 K cooler than that expected from the infrared flux method, depending on the adopted extinction map, which provides evidence for a lower value on average than that inferred for the Kepler Input Catalog (KIC). We find a reasonable correspondence between the photometric KIC and spectroscopic APOKASC metallicity scales, with increased dispersion in KIC metallicities as the absolute metal abundance decreases, and offsets in T {sub eff} and log g consistent with those derived in the literature. We present mean fitting relations between APOKASC and KIC observables and discuss future prospects, strengths, and limitations of the catalog data.

Grading of cerebral gilomas: correlation with perfusion MRI, spectroscopic MRI and histopathology

International Nuclear Information System (INIS)

Law, M.; Cha, S.; Knopp, E.A.; Johnson, G.; Litt, A.W.

2002-01-01

Full text: The aim of this study was to determine the correlation between perfusion MRI (pMRI), spectroscopic MRI (sMRI) and histopathologic grading of primary glial neoplasms. Echo-planar pMRI has already been shown to be a robust physiological tool in preoperatively predicting tumor grade and guiding stereotactic biopsy (1). Thirty-four patients with a primary glial neoplasm underwent conventional MR imaging, T2*-weighted echo planar pMRI and sMRI. Four rCBV measurements were obtained from the colour maps of each lesion to determine the maximum rCBV. Spectroscopic MRI utilizing 2D chemical shift imaging at a TE of 135 provided multi-voxel spectroscopic data in sixteen of these patients. The maximum Cho/NAA, Cho/Cr, and minimum NAA/Cr ratios were obtained as well as documenting the presence of lactate and lipids. This was compared with the histopathological grading (including staining with H and E, GFAP, vimentin and MIB1, proliferative index) obtained from volumetric resection or stereotactic biopsy. The maximum rCBV in high grade tumors (n=26) ranged from 1.34 to 5.15, with a mean of 3.00 ± 1.21 (SD), and in the low grade tumors (n=8) ranged from 1.47 to 2.49, with a mean of 1.81 ± 1.21 (SD).This difference was statistically significant (p<0.001; Student t test). Maximum values for Cho/NAA, Cho/Cr and minimum NAA/Cr values were 3.24 ± 3.26, 2.49 ± 1.17 and 1.02 ± 0.34, respectively in the high grade (n = 11), and 1.3 ± 0.39, 1.58 ± 0.45 and 0.89 ± 0.37 respectively in the low-grade tumors (n = 5). A statistically significant difference was found for the Cho/Cr ratio (p<0.05) between the high grade and low grade groups. Relative CBV measurements and spectroscopic metabolic ratios are complementary and correlate with histopathology (2,3). These tools provide powerful physiological and metabolic information for preoperative prediction of tumor grade and will guide pre and post operative planning and management. Copyright (2002) Blackwell Science Pty Ltd

Sequence-specific bias correction for RNA-seq data using recurrent neural networks.

Science.gov (United States)

Zhang, Yao-Zhong; Yamaguchi, Rui; Imoto, Seiya; Miyano, Satoru

2017-01-25

The recent success of deep learning techniques in machine learning and artificial intelligence has stimulated a great deal of interest among bioinformaticians, who now wish to bring the power of deep learning to bare on a host of bioinformatical problems. Deep learning is ideally suited for biological problems that require automatic or hierarchical feature representation for biological data when prior knowledge is limited. In this work, we address the sequence-specific bias correction problem for RNA-seq data redusing Recurrent Neural Networks (RNNs) to model nucleotide sequences without pre-determining sequence structures. The sequence-specific bias of a read is then calculated based on the sequence probabilities estimated by RNNs, and used in the estimation of gene abundance. We explore the application of two popular RNN recurrent units for this task and demonstrate that RNN-based approaches provide a flexible way to model nucleotide sequences without knowledge of predetermined sequence structures. Our experiments show that training a RNN-based nucleotide sequence model is efficient and RNN-based bias correction methods compare well with the-state-of-the-art sequence-specific bias correction method on the commonly used MAQC-III data set. RNNs provides an alternative and flexible way to calculate sequence-specific bias without explicitly pre-determining sequence structures.

Effects of informed consent for individual genome sequencing on relevant knowledge.

Science.gov (United States)

Kaphingst, K A; Facio, F M; Cheng, M-R; Brooks, S; Eidem, H; Linn, A; Biesecker, B B; Biesecker, L G

2012-11-01

Increasing availability of individual genomic information suggests that patients will need knowledge about genome sequencing to make informed decisions, but prior research is limited. In this study, we examined genome sequencing knowledge before and after informed consent among 311 participants enrolled in the ClinSeq™ sequencing study. An exploratory factor analysis of knowledge items yielded two factors (sequencing limitations knowledge; sequencing benefits knowledge). In multivariable analysis, high pre-consent sequencing limitations knowledge scores were significantly related to education [odds ratio (OR): 8.7, 95% confidence interval (CI): 2.45-31.10 for post-graduate education, and OR: 3.9; 95% CI: 1.05, 14.61 for college degree compared with less than college degree] and race/ethnicity (OR: 2.4, 95% CI: 1.09, 5.38 for non-Hispanic Whites compared with other racial/ethnic groups). Mean values increased significantly between pre- and post-consent for the sequencing limitations knowledge subscale (6.9-7.7, p benefits knowledge subscale (7.0-7.5, p < 0.0001); increase in knowledge did not differ by sociodemographic characteristics. This study highlights gaps in genome sequencing knowledge and underscores the need to target educational efforts toward participants with less education or from minority racial/ethnic groups. The informed consent process improved genome sequencing knowledge. Future studies could examine how genome sequencing knowledge influences informed decision making. © 2012 John Wiley & Sons A/S.

Association of hepatitis B virus pre-S deletions with the development of hepatocellular carcinoma in Qidong, China.

Directory of Open Access Journals (Sweden)

Li-Shuai Qu

Full Text Available BACKGROUND/AIM: To investigate the roles of mutations in pre-S and S regions of hepatitis B virus (HBV on the progression of hepatocellular carcinoma (HCC in Qidong, China. METHODS: We conducted an age matched case-control study within a cohort of 2387 male HBV carriers who were recruited from August, 1996. The HBV DNA sequence in pre-S/S regions was successfully determined in 96 HCC cases and 97 control subjects. In addition, a consecutive series of samples from 11 HCC cases were employed to evaluate the pre-S deletion patterns before and after the occurrence of HCC. RESULTS: After adjustment for age, history of cigarette smoking and alcohol consumption, HBeAg positivity, pre-S deletions, pre-S2 start codon mutations, and T53C mutation were significantly associated with HCC, showing adjusted odds ratios (ORs from 1.914 to 3.199. HCC patients also had a lower frequency of T31C mutation in pre-S2 gene, compared with control subjects (0.524; 95% CI 0.280-0.982. HBV pre-S deletions were clustered mainly in the 5' end of pre-S2 region. Multivariate analysis showed that pre-S deletions and pre-S2 start codon mutations were independent risk factors for HCC. The OR (95% CI were 2.434 (1.063-5.573 and 3.065 (1.099-8.547, respectively. The longitudinal observation indicated that the pre-S deletion mutations were not acquired at the beginning of HBV infection, but that the mutations occurred during the long course of liver disease. CONCLUSION: Pre-S deletions and pre-S2 start codon mutations were independently associated with the development of HCC. The results also provided direct evidence that pre-S deletion mutations were not acquired from the beginning of infection but arose de novo during the progression of liver disease.

Detection of [O III] at z ∼ 3: A Galaxy Above the Main Sequence, Rapidly Assembling Its Stellar Mass

Science.gov (United States)

Vishwas, Amit; Ferkinhoff, Carl; Nikola, Thomas; Parshley, Stephen C.; Schoenwald, Justin P.; Stacey, Gordon J.; Higdon, Sarah J. U.; Higdon, James L.; Weiss, Axel; Güsten, Rolf; Menten, Karl M.

2018-04-01

We detect bright emission in the far-infrared (far-IR) fine structure [O III] 88 μm line from a strong lensing candidate galaxy, H-ATLAS J113526.3-014605, hereafter G12v2.43, at z = 3.127, using the second-generation Redshift (z) and Early Universe Spectrometer (ZEUS-2) at the Atacama Pathfinder Experiment Telescope (APEX). This is only the fifth detection of this far-IR line from a submillimeter galaxy at the epoch of galaxy assembly. The observed [O III] luminosity of 7.1 × 109 ≤ft(\\tfrac{10}{μ }\\right) L ⊙ likely arises from H II regions around massive stars, and the amount of Lyman continuum photons required to support the ionization indicate the presence of (1.2–5.2) × 106 ≤ft(\\tfrac{10}{μ }\\right) equivalent O5.5 or higher stars, where μ would be the lensing magnification factor. The observed line luminosity also requires a minimum mass of ∼2 × 108 ≤ft(\\tfrac{10}{μ }\\right) M ⊙ in ionized gas, that is 0.33% of the estimated total molecular gas mass of 6 × 1010 ≤ft(\\tfrac{10}{μ }\\right) M ⊙. We compile multi-band photometry tracing rest-frame ultraviolet to millimeter continuum emission to further constrain the properties of this dusty high-redshift, star-forming galaxy. Via SED modeling we find G12v2.43 is forming stars at a rate of 916 ≤ft(\\tfrac{10}{μ }\\right) M ⊙ yr‑1 and already has a stellar mass of 8 × 1010 ≤ft(\\tfrac{10}{μ }\\right) M ⊙. We also constrain the age of the current starburst to be ≤slant 5 Myr, making G12v2.43 a gas-rich galaxy lying above the star-forming main sequence at z ∼ 3, undergoing a growth spurt, and it could be on the main sequence within the derived gas depletion timescale of ∼66 Myr.

Minimum TE gradient-recalled phosphorus imaging sequence on a whole-body imager

International Nuclear Information System (INIS)

Listerud, J.; Lenkinski, R.E.; Axel, L.

1989-01-01

To define the lower limits of spatial resolution in gradient-recalled echo phosphorus studies at 1.5 T, the authors have implemented a phosphorus gradient-recalled imaging sequence on the Signa imager. All gradient ramps for the section-selective rephasing lobe, the phase-encoding pulse, and the dephasing pulse of the frequency-encoding gradient are slowed at the maximal rate. Consequently, with a field of view of 24 cm, an in-plane resolution of 3 cm, an echo appropriately offset, an RF bandwidth of 1.2 KHz, and a section thickness of 5 cm, the echo time may be reduced to 1.35 msec. The reconstruction algorithm has been modified to support oversampled data of low spatial resolution appropriate for phosphorus imaging. The sequence will acquire H-1 images and supports the automatic and manual prescan features of the commercial instrument. To facilitate setup in the phosphorus imaging mode the sequence supports the product spectroscopic mode with a DRESS (depth recalled surface coil spectroscopy) sequence and a section profile sequence for appropriate shimming, receiver characteristics, and averaging requirements. The suitability for adaptation of this sequence to three-dimensional chemical shift imaging is discussed

PG 1316+678: A young pre-cataclysmic binary with weak reflection effects

Science.gov (United States)

Shimansky, V. V.; Borisov, N. V.; Bikmaev, I. F.; Sakhibullin, N. A.; Shimanskaya, N. N.; Spiridonova, O. I.; Irtuganov, E. N.

2013-03-01

The PG 1316+678 star is classified as a pre-cataclysmic binary, as is evidenced by its photometric and spectroscopic observations. Its orbital period is determined to be P orb = 3.3803d, which coincides with the photometric period. The intensities of the emission HI and HeI lines are shown to vary synchronously with the brightness of the object (Δ m V = 0.065 m , Δ m R = 0.08 m ). These variations arise as the UV radiation from the DAO white dwarf is reflected from the surface of the cold companion. The parameters of the binary are estimated and the time of its evolution after the common-envelope phase is determined to be t ≈ 240 000 years. Thus, PG 1316+678 is a young pre-cataclysmic NN Ser variable with the smallest known photometric reflection effect.

Spectroscopic analysis of radiation-generated changes in tensile properties of a polyetherimide film

International Nuclear Information System (INIS)

Long, E.R. Jr.; Long, S.A.T.

1985-05-01

The effects of electron radiation on Ultem, a polyetherimide were studied for doses from 2 x 10 to the 9th power to 6 x 10 to the 9th power rad. Specimens were studied for tensile property testing and for electron paramagnetic resonance and infrared spectroscopic measurements of molecular structure. A Faraday cup design and a method for remote temperature measurement were developed. The spectroscopic data show that radiation caused dehydrogenation of methyl groups, rupture of main-chain ether linkage, and opening of imide rings, all to form radicals and indicate that the so-formed atomic hydrogen attached to phenyl radicals, but not to phenoxyl radicals, which would have formed hydroxyls. The observed decays of the radiation-generated phenoxyl, gem-dimethyl, and carbonyl radicals were interpreted as a combining of the radicals to form crosslinking. This crosslinking is the probable cause of the major reduction in the elongation of the tensile specimens after irradiation. Subsequent classical solubility tests indicate that the irradiation caused massive crosslinking

Strong linkages between DOM optical properties and main clades of aquatic bacteria

DEFF Research Database (Denmark)

Amaral, Valentina; Graeber, Daniel; Calliari, Danilo

2016-01-01

–emission fluorescence spectroscopy and spectroscopic indexes to characterize DOM composition, and fluorescence in situ hybridization, to quantify the major bacterial groups in a subtropical lagoon. The DOM exhibited marked temporal variations in concentration, molecular weight, aromaticity, color, degree...... properties. Alphaproteobacteria and Gammaproteobacteria abundances were significantly explained by low or high dissolved organic carbon concentrations, respectively. The significant relationships between DOM properties and the main bacterial groups delineated a profile of each group regarding DOM preferences...

Excitation of Solar-like Oscillations: From PMS to MS Stellar Models ...

Indian Academy of Sciences (India)

excited modes in pre-main sequence stars are also discussed. Key words. Turbulence—convection—oscillations—excitation—sun, stars: α Cen A—stars: main and pre-main sequence stars. 1. Introduction. In the past approximately five years, solar-like oscillations have been detected in several intermediate massive stars ...

The intermediate-age pre-cataclysmic variables SDSS J172406+562003 and RE J2013+4002

Science.gov (United States)

Shimansky, V. V.; Borisov, N. V.; Nurtdinova, D. N.; Mitrofanova, A. A.; Vlasyuk, V. V.; Spiridonova, O. I.

2012-06-01

We have analyzed the physical status of the pre-cataclysmic variables SDSSJ172406+562003 and RE J2013+4002, which have evolved after their common-envelope stage a time t = 106-107 years. Spectroscopy and photometry of these systems were performed with the 6-m and 1-m telescopes of the Special Astrophysical Observatory. We demonstrate that emission lines in the spectra were formed solely by the reflection of radiation emitted by the white dwarfs on the surfaces of their cool companions, under conditions close to local thermodynamic equilibrium. These effects are also responsible for most of the objects' photometric variability amplitude. However, comparing the light curves of SDSS 172406 from different epochs, we find aperiodic brightness variations, probably due to spottedness of the surface of the secondary. Jointly analyzing the spectra, radial-velocity curves, and light curves of the pre-cataclysmic variables and modeling the reflection effects, we have derived their fundamental parameters. We demonstrate that the secondaries in these systems are consistent with evolutionary models for main-sequence stars and do not have the luminosity excesses characteristic of cool stars in young pre-cataclysmic variables.

Making the most of RNA-seq: Pre-processing sequencing data with Opossum for reliable SNP variant detection [version 2; referees: 2 approved, 1 approved with reservations

Directory of Open Access Journals (Sweden)

Laura Oikkonen

2017-03-01

Full Text Available Identifying variants from RNA-seq (transcriptome sequencing data is a cost-effective and versatile complement to whole-exome (WES and whole-genome sequencing (WGS analysis. RNA-seq (transcriptome sequencing is primarily considered a method of gene expression analysis but it can also be used to detect DNA variants in expressed regions of the genome. However, current variant callers do not generally behave well with RNA-seq data due to reads encompassing intronic regions. We have developed a software programme called Opossum to address this problem. Opossum pre-processes RNA-seq reads prior to variant calling, and although it has been designed to work specifically with Platypus, it can be used equally well with other variant callers such as GATK HaplotypeCaller. In this work, we show that using Opossum in conjunction with either Platypus or GATK HaplotypeCaller maintains precision and improves the sensitivity for SNP detection compared to the GATK Best Practices pipeline. In addition, using it in combination with Platypus offers a substantial reduction in run times compared to the GATK pipeline so it is ideal when there are only limited time or computational resources available.

Alternative splicing affects the targeting sequence of peroxisome proteins in Arabidopsis.

Science.gov (United States)

An, Chuanjing; Gao, Yuefang; Li, Jinyu; Liu, Xiaomin; Gao, Fuli; Gao, Hongbo

2017-07-01

A systematic analysis of the Arabidopsis genome in combination with localization experiments indicates that alternative splicing affects the peroxisomal targeting sequence of at least 71 genes in Arabidopsis. Peroxisomes are ubiquitous eukaryotic cellular organelles that play a key role in diverse metabolic functions. All peroxisome proteins are encoded by nuclear genes and target to peroxisomes mainly through two types of targeting signals: peroxisomal targeting signal type 1 (PTS1) and PTS2. Alternative splicing (AS) is a process occurring in all eukaryotes by which a single pre-mRNA can generate multiple mRNA variants, often encoding proteins with functional differences. However, the effects of AS on the PTS1 or PTS2 and the targeting of the protein were rarely studied, especially in plants. Here, we systematically analyzed the genome of Arabidopsis, and found that the C-terminal targeting sequence PTS1 of 66 genes and the N-terminal targeting sequence PTS2 of 5 genes are affected by AS. Experimental determination of the targeting of selected protein isoforms further demonstrated that AS at both the 5' and 3' region of a gene can affect the inclusion of PTS2 and PTS1, respectively. This work underscores the importance of AS on the global regulation of peroxisome protein targeting.

Defect study in ZnO related structures-A multi-spectroscopic approach

International Nuclear Information System (INIS)

Ling, C.C.; Cheung, C.K.; Gu, Q.L.; Dai, X.M.; Xu, S.J.; Zhu, C.Y.; Luo, J.M.; Zhu, C.Y.; Tam, K.H.; Djurisic, A.B.; Beling, C.D.; Fung, S.; Lu, L.W.; Brauer, G.; Anwand, W.; Skorupa, W.; Ong, H.C.

2008-01-01

ZnO has attracted a great deal of attention in recent years because of its potential applications for fabricating optoelectronic devices. Using a multi-spectroscopic approach including positron annihilation spectroscopy (PAS), deep level transient spectroscopy (DLTS), photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS), we have studied the two observed phenomena from ZnO related structures. They namely included the H 2 O 2 pre-treatment induced ohmic to rectifying contact conversion on Au/n-ZnO contact and the p-type doping by nitrogen ion implantation. The aim of the studies was to offering comprehensive views as to how the defects influenced the structures electrical and optical properties of the structures. It was also shown that PAS measurement using the monoenergetic positron beam could offer valuable information of vacancy type defects in the vertical ZnO nanorod array structure

Defect study in ZnO related structures-A multi-spectroscopic approach

Energy Technology Data Exchange (ETDEWEB)

Ling, C.C. [Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong (China)], E-mail: ccling@hku.hk; Cheung, C.K.; Gu, Q.L.; Dai, X.M.; Xu, S.J.; Zhu, C.Y.; Luo, J.M.; Zhu, C.Y.; Tam, K.H.; Djurisic, A.B.; Beling, C.D.; Fung, S.; Lu, L.W. [Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong (China); Brauer, G.; Anwand, W.; Skorupa, W. [Institut fuer Ionenstrahlphysik und Materialforschung, Forschungszentrum Dresden-Rossendorf, Postfach 510119, D-01314 Dresden (Germany); Ong, H.C. [Department of Physics, Chinese University of Hong Kong, Shatin, Hong Kong (China)

2008-10-31

ZnO has attracted a great deal of attention in recent years because of its potential applications for fabricating optoelectronic devices. Using a multi-spectroscopic approach including positron annihilation spectroscopy (PAS), deep level transient spectroscopy (DLTS), photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS), we have studied the two observed phenomena from ZnO related structures. They namely included the H{sub 2}O{sub 2} pre-treatment induced ohmic to rectifying contact conversion on Au/n-ZnO contact and the p-type doping by nitrogen ion implantation. The aim of the studies was to offering comprehensive views as to how the defects influenced the structures electrical and optical properties of the structures. It was also shown that PAS measurement using the monoenergetic positron beam could offer valuable information of vacancy type defects in the vertical ZnO nanorod array structure.

Defect study in ZnO related structures—A multi-spectroscopic approach

Science.gov (United States)

Ling, C. C.; Cheung, C. K.; Gu, Q. L.; Dai, X. M.; Xu, S. J.; Zhu, C. Y.; Luo, J. M.; Zhu, C. Y.; Tam, K. H.; Djurišić, A. B.; Beling, C. D.; Fung, S.; Lu, L. W.; Brauer, G.; Anwand, W.; Skorupa, W.; Ong, H. C.

2008-10-01

ZnO has attracted a great deal of attention in recent years because of its potential applications for fabricating optoelectronic devices. Using a multi-spectroscopic approach including positron annihilation spectroscopy (PAS), deep level transient spectroscopy (DLTS), photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS), we have studied the two observed phenomena from ZnO related structures. They namely included the H 2O 2 pre-treatment induced ohmic to rectifying contact conversion on Au/ n-ZnO contact and the p-type doping by nitrogen ion implantation. The aim of the studies was to offering comprehensive views as to how the defects influenced the structures electrical and optical properties of the structures. It was also shown that PAS measurement using the monoenergetic positron beam could offer valuable information of vacancy type defects in the vertical ZnO nanorod array structure.

THE EXTENDED MAIN-SEQUENCE TURNOFF CLUSTERS OF THE LARGE MAGELLANIC CLOUD-MISSING LINKS IN GLOBULAR CLUSTER EVOLUTION

International Nuclear Information System (INIS)

Keller, Stefan C.; Mackey, A. Dougal; Da Costa, Gary S.

2011-01-01

Recent observations of intermediate-age (1-3 Gyr) massive star clusters in the Large Magellanic Cloud have revealed that the majority possess bifurcated or extended main-sequence turnoff (EMSTO) morphologies. This effect can be understood to arise from subsequent star formation among the stellar population with age differences between constituent stars amounting to 50-300 Myr. Age spreads of this order are similarly invoked to explain the light-element abundance variations witnessed in ancient globular clusters (GCs). In this paper, we explore the proposition that the clusters exhibiting the EMSTO phenomenon are a general phase in the evolution of massive clusters, one that naturally leads to the particular chemical properties of the ancient GC population. We show that the isolation of EMSTO clusters to intermediate ages is the consequence of observational selection effects. In our proposed scenario, the EMSTO phenomenon is identical to that which establishes the light-element abundance variations that are ubiquitous in the ancient GC population. Our scenario makes a strong prediction: EMSTO clusters will exhibit abundance variations in the light-elements characteristic of the ancient GC population.

THE PROGENITOR DEPENDENCE OF THE PRE-EXPLOSION NEUTRINO EMISSION IN CORE-COLLAPSE SUPERNOVAE

International Nuclear Information System (INIS)

O'Connor, Evan; Ott, Christian D.

2013-01-01

We perform spherically symmetric general-relativistic simulations of core collapse and the postbounce pre-explosion phase in 32 presupernova stellar models of solar metallicity with zero-age main-sequence masses of 12-120 M ☉ . Using energy-dependent three-species neutrino transport in the two-moment approximation with an analytic closure, we show that the emitted neutrino luminosities and spectra follow very systematic trends that are correlated with the compactness (∼M/R) of the progenitor star's inner regions via the accretion rate in the pre-explosion phase. We find that these qualitative trends depend only weakly on the nuclear equation of state (EOS), but quantitative observational statements will require independent constraints on the EOS and the rotation rate of the core as well as a more complete understanding of neutrino oscillations. We investigate the simulated response of water Cherenkov detectors to the electron antineutrino fluxes from our models and find that the large statistics of a galactic core collapse event may allow robust conclusions on the inner structure of the progenitor star.

THE PROGENITOR DEPENDENCE OF THE PRE-EXPLOSION NEUTRINO EMISSION IN CORE-COLLAPSE SUPERNOVAE

Energy Technology Data Exchange (ETDEWEB)

O' Connor, Evan; Ott, Christian D., E-mail: evanoc@tapir.caltech.edu, E-mail: cott@tapir.caltech.edu [TAPIR, California Institute of Technology, Mailcode 350-17, Pasadena, CA 91125 (United States)

2013-01-10

We perform spherically symmetric general-relativistic simulations of core collapse and the postbounce pre-explosion phase in 32 presupernova stellar models of solar metallicity with zero-age main-sequence masses of 12-120 M {sub Sun }. Using energy-dependent three-species neutrino transport in the two-moment approximation with an analytic closure, we show that the emitted neutrino luminosities and spectra follow very systematic trends that are correlated with the compactness ({approx}M/R) of the progenitor star's inner regions via the accretion rate in the pre-explosion phase. We find that these qualitative trends depend only weakly on the nuclear equation of state (EOS), but quantitative observational statements will require independent constraints on the EOS and the rotation rate of the core as well as a more complete understanding of neutrino oscillations. We investigate the simulated response of water Cherenkov detectors to the electron antineutrino fluxes from our models and find that the large statistics of a galactic core collapse event may allow robust conclusions on the inner structure of the progenitor star.

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

International Nuclear Information System (INIS)

Leaman, Ryan

2012-01-01

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

Fundamental spectroscopic studies of carbenes and hydrocarbon radicals

Energy Technology Data Exchange (ETDEWEB)

Gottlieb, C.A.; Thaddeus, P. [Harvard Univ., Cambridge, MA (United States)

1993-12-01

Highly reactive carbenes and carbon-chain radicals are studied at millimeter wavelengths by observing their rotational spectra. The purpose is to provide definitive spectroscopic identification, accurate spectroscopic constants in the lowest vibrational states, and reliable structures of the key intermediates in reactions leading to aromatic hydrocarbons and soot particles in combustion.

Mitochondrial import of human and yeast fumarase in live mammalian cells: Retrograde translocation of the yeast enzyme is mainly caused by its poor targeting sequence

International Nuclear Information System (INIS)

Singh, Bhag; Gupta, Radhey S.

2006-01-01

Studies on yeast fumarase provide the main evidence for dual localization of a protein in mitochondria and cytosol by means of retrograde translocation. We have examined the subcellular targeting of yeast and human fumarase in live cells to identify factors responsible for this. The cDNAs for mature yeast or human fumarase were fused to the gene for enhanced green fluorescent protein (eGFP) and they contained, at their N-terminus, a mitochondrial targeting sequence (MTS) derived from either yeast fumarase, human fumarase, or cytochrome c oxidase subunit VIII (COX) protein. Two nuclear localization sequences (2x NLS) were also added to these constructs to facilitate detection of any cytosolic protein by its targeting to nucleus. In Cos-1 cells transfected with these constructs, human fumarase with either the native or COX MTSs was detected exclusively in mitochondria in >98% of the cells, while the remainder 1-2% of the cells showed varying amounts of nuclear labeling. In contrast, when human fumarase was fused to the yeast MTS, >50% of the cells showed nuclear labeling. Similar studies with yeast fumarase showed that with its native MTS, nuclear labeling was seen in 80-85% of the cells, but upon fusion to either human or COX MTS, nuclear labeling was observed in only 10-15% of the cells. These results provide evidence that extramitochondrial presence of yeast fumarase is mainly caused by the poor mitochondrial targeting characteristics of its MTS (but also affected by its primary sequence), and that the retrograde translocation mechanism does not play a significant role in the extramitochondrial presence of mammalian fumarase

Sequence Factorization with Multiple References.

Directory of Open Access Journals (Sweden)

Sebastian Wandelt

Full Text Available The success of high-throughput sequencing has lead to an increasing number of projects which sequence large populations of a species. Storage and analysis of sequence data is a key challenge in these projects, because of the sheer size of the datasets. Compression is one simple technology to deal with this challenge. Referential factorization and compression schemes, which store only the differences between input sequence and a reference sequence, gained lots of interest in this field. Highly-similar sequences, e.g., Human genomes, can be compressed with a compression ratio of 1,000:1 and more, up to two orders of magnitude better than with standard compression techniques. Recently, it was shown that the compression against multiple references from the same species can boost the compression ratio up to 4,000:1. However, a detailed analysis of using multiple references is lacking, e.g., for main memory consumption and optimality. In this paper, we describe one key technique for the referential compression against multiple references: The factorization of sequences. Based on the notion of an optimal factorization, we propose optimization heuristics and identify parameter settings which greatly influence 1 the size of the factorization, 2 the time for factorization, and 3 the required amount of main memory. We evaluate a total of 30 setups with a varying number of references on data from three different species. Our results show a wide range of factorization sizes (optimal to an overhead of up to 300%, factorization speed (0.01 MB/s to more than 600 MB/s, and main memory usage (few dozen MB to dozens of GB. Based on our evaluation, we identify the best configurations for common use cases. Our evaluation shows that multi-reference factorization is much better than single-reference factorization.

The origin of the RS CVn binaries

International Nuclear Information System (INIS)

Biermann, P.

1976-01-01

Six possible origins for the RS CVn binaries are considered based on the following possibilities. RS CVn binaries might now be either pre-main-sequence or post-main-sequence. A pre-main-sequence binary might not always have been a binary but might have resulted from fission of a rapidly rotating single pre-main-sequence star. The main-sequence counterparts might be either single stars or binaries. To decide which of the six origins is possible, the following observed data for the RS CVn binaries are considered: total mass, total angular momentum, lack of observed connection with regions of star formation, large space density, kinematical age, and the visual companion of WW Dra. In addition lifetimes and space densities of single stars and other types of binaries are considered. The only origin possible is that the RS CVn binaries are in a thermal phase following fission of a main-sequence single star. In this explanation the single star had a rapidly rotating core which became unstable due to the core contraction which made it begin to evolve off the main sequence. The present Be stars might be examples of such parent single stars. (Auth.)

Noninvasive, near infrared spectroscopic-measured muscle pH and PO2 indicate tissue perfusion for cardiac surgical patients undergoing cardiopulmonary bypass

Science.gov (United States)

Soller, Babs R.; Idwasi, Patrick O.; Balaguer, Jorge; Levin, Steven; Simsir, Sinan A.; Vander Salm, Thomas J.; Collette, Helen; Heard, Stephen O.

2003-01-01

OBJECTIVE: To determine whether near infrared spectroscopic measurement of tissue pH and Po2 has sufficient accuracy to assess variation in tissue perfusion resulting from changes in blood pressure and metabolic demand during cardiopulmonary bypass. DESIGN: Prospective clinical study. SETTING: Academic medical center. SUBJECTS: Eighteen elective cardiac surgical patients. INTERVENTION: Cardiac surgery under cardiopulmonary bypass. MEASUREMENTS AND MAIN RESULTS: A near infrared spectroscopic fiber optic probe was placed over the hypothenar eminence. Reference Po2 and pH sensors were inserted in the abductor digiti minimi (V). Data were collected every 30 secs during surgery and for 6 hrs following cardiopulmonary bypass. Calibration equations developed from one third of the data were used with the remaining data to investigate sensitivity of the near infrared spectroscopic measurement to physiologic changes resulting from cardiopulmonary bypass. Near infrared spectroscopic and reference pH and Po2 measurements were compared for each subject using standard error of prediction. Near infrared spectroscopic pH and Po2 at baseline were compared with values during cardiopulmonary bypass just before rewarming commenced (hypotensive, hypothermic), after rewarming (hypotensive, normothermic) just before discontinuation of cardiopulmonary bypass, and at 6 hrs following cardiopulmonary bypass (normotensive, normothermic) using mixed-model analysis of variance. Near infrared spectroscopic pH and Po2 were well correlated with the invasive measurement of pH (R2 =.84) and Po2 (R 2 =.66) with an average standard error of prediction of 0.022 +/- 0.008 pH units and 6 +/- 3 mm Hg, respectively. The average difference between the invasive and near infrared spectroscopic measurement was near zero for both the pH and Po2 measurements. Near infrared spectroscopic Po2 significantly decreased 50% on initiation of cardiopulmonary bypass and remained depressed throughout the bypass and

Interaction of tea polyphenols with serum albumins: A fluorescence spectroscopic analysis

Energy Technology Data Exchange (ETDEWEB)

Bose, Adity, E-mail: adityc17j@gmail.com

2016-01-15

Interactions of some tea polyphenols, namely (−) Catechin (C), (−)-epicatechin (EC), (–) epicatechin-3-gallate (ECG), (−)-epigallocatechin (EGC) and (−)-epigallocatechin-3-gallate (EGCG) are outlined with the serum albumin proteins. These interactions had all resulted in binding with the proteins with a concomitant static quenching of the protein fluorescence. A fluorescence technique has been considered as the tool to comprehend the polyphenol–protein interactions mainly and simultaneously other spectroscopic techniques used to verify the results have been discussed. In this mini review the different types of equations usually employed to calculate the binding constant values have been outlined, namely, modified Stern Volmer plot, Scatchard plot and Lineweaver Burk equation, with their corresponding results. The n values (number of binding sites) had always been close to unity suggesting a 1:1 complexation with the polyphenols and the protein. A structural change in the polyphenols has been found to alter the binding constant value and the galloyl moiety attached to the C ring of the polyphenols have been found to play a crucial role in this regard. It has been found that an increase in galloyl moiety increases binding of the catechins with proteins. - Highlights: • Review on interactions of some tea polyphenols with the serum albumin proteins. • Tea polyphenols include Catechin, epigallocatechin-3-gallate, epigallocatechin, epicatechin-3-gallate and epicatechin. • Fluorescence spectroscopic technique is mainly outlined. • Binding constant studies have been given importance. • Galloyl moiety in the C ring is crucial in increasing binding constant.

Gas Chromatography-Mass Spectroscopic (GC-MS) Analysis of n ...

African Journals Online (AJOL)

tuber-regium (synonym Pleurotus tuber regium) using gas chromatography-mass spectroscopic (GC-. MS) techniques. Methods: The n-hexane extract of the sclerotia ... Soxhlet extraction and analysed using gas chromatography-mass spectroscopic (MS) techniques. ..... Phytochemical composition of Pleurotus tuber regium.

Optical constants of graphene measured by spectroscopic ellipsometry

NARCIS (Netherlands)

Weber, J.W.; Calado, V.E.; Van de Sanden, M.C.M.

2010-01-01

A mechanically exfoliated graphene flake ( ? 150×380??m2) on a silicon wafer with 98 nm silicon dioxide on top was scanned with a spectroscopic ellipsometer with a focused spot ( ? 100×55??m2) at an angle of 55°. The spectroscopic ellipsometric data were analyzed with an optical model in which the

Optical constants of graphene measured by spectroscopic ellipsometry

NARCIS (Netherlands)

Weber, J.W.; Calado, V.E.; Sanden, van de M.C.M.

2010-01-01

A mechanically exfoliated graphene flake ( ~ 150×380 µm2) on a silicon wafer with 98 nm silicon dioxide on top was scanned with a spectroscopic ellipsometer with a focused spot ( ~ 100×55 µm2) at an angle of 55°. The spectroscopic ellipsometric data were analyzed with an optical model in which the

A Spectroscopic Study of Young Stellar Objects in the Serpens Cloud Core and NGC 1333

Science.gov (United States)

Winston, E.; Megeath, S. T.; Wolk, S. J.; Hernandez, J.; Gutermuth, R.; Muzerolle, J.; Hora, J. L.; Covey, K.; Allen, L. E.; Spitzbart, B.; Peterson, D.; Myers, P.; Fazio, G. G.

2009-06-01

We present spectral observations of 130 young stellar objects (YSOs) in the Serpens Cloud Core and NGC 1333 embedded clusters. The observations consist of near-IR spectra in the H and K bands from SpeX on the IRTF and far-red spectra (6000-9000 Å) from Hectospec on the Multi-Mirror Telescope. These YSOs were identified in previous Spitzer and Chandra observations, and the evolutionary classes of the YSOs were determined from the Spitzer mid-IR photometry. With these spectra we search for corroborating evidence for the pre-main-sequence nature of the objects, study the properties of the detected emission lines as a function of evolutionary class, and obtain spectral types for the observed YSOs. The temperatures implied by the spectral types are combined with luminosities determined from the near-IR photometry to construct Hertzsprung-Russell (H-R) diagrams for the clusters. By comparing the positions of the YSOs in the H-R diagrams with the pre-main-sequence tracks of Baraffe (1998), we determine the ages of the embedded sources and study the relative ages of the YSOs with and without optically thick circumstellar disks. The apparent isochronal ages of the YSOs in both clusters range from less than 1 Myr to 10 Myr, with most objects below 3 Myr. The observed distributions of ages for the Class II and Class III objects are statistically indistinguishable. We examine the spatial distribution and extinction of the YSOs as a function of their isochronal ages. We find the sources dispersed and are not deeply embedded. Nonetheless, the sources with isochronal ages >3 Myr show all the characteristics of YSOs in their spectra, their IR spectral energy distributions, and their X-ray emission; we find no evidence that they are contaminating background giants or foreground dwarfs. However, we find no corresponding decrease in the fraction of sources with infrared excess with isochronal age; this suggests that the older isochronal ages may not measure the true age of the >3

Making the most of RNA-seq: Pre-processing sequencing data with Opossum for reliable SNP variant detection [version 1; referees: 2 approved, 1 approved with reservations

Directory of Open Access Journals (Sweden)

Laura Oikkonen

2017-01-01

Full Text Available Identifying variants from RNA-seq (transcriptome sequencing data is a cost-effective and versatile alternative to whole-genome sequencing. However, current variant callers do not generally behave well with RNA-seq data due to reads encompassing intronic regions. We have developed a software programme called Opossum to address this problem. Opossum pre-processes RNA-seq reads prior to variant calling, and although it has been designed to work specifically with Platypus, it can be used equally well with other variant callers such as GATK HaplotypeCaller. In this work, we show that using Opossum in conjunction with either Platypus or GATK HaplotypeCaller maintains precision and improves the sensitivity for SNP detection compared to the GATK Best Practices pipeline. In addition, using it in combination with Platypus offers a substantial reduction in run times compared to the GATK pipeline so it is ideal when there are only limited time or computational resources available.

Spectroscopic characterization of low dose rate brachytherapy sources

Science.gov (United States)

Beach, Stephen M.

The low dose rate (LDR) brachytherapy seeds employed in permanent radioactive-source implant treatments usually use one of two radionuclides, 125I or 103Pd. The theoretically expected source spectroscopic output from these sources can be obtained via Monte Carlo calculation based upon seed dimensions and materials as well as the bare-source photon emissions for that specific radionuclide. However the discrepancies resulting from inconsistent manufacturing of sources in comparison to each other within model groups and simplified Monte Carlo calculational geometries ultimately result in undesirably large uncertainties in the Monte Carlo calculated values. This dissertation describes experimentally attained spectroscopic outputs of the clinically used brachytherapy sources in air and in liquid water. Such knowledge can then be applied to characterize these sources by a more fundamental and metro logically-pure classification, that of energy-based dosimetry. The spectroscopic results contained within this dissertation can be utilized in the verification and benchmarking of Monte Carlo calculational models of these brachytherapy sources. This body of work was undertaken to establish a usable spectroscopy system and analysis methods for the meaningful study of LDR brachytherapy seeds. The development of a correction algorithm and the analysis of the resultant spectroscopic measurements are presented. The characterization of the spectrometer and the subsequent deconvolution of the measured spectrum to obtain the true spectrum free of any perturbations caused by the spectrometer itself is an important contribution of this work. The approach of spectroscopic deconvolution that was applied in this work is derived in detail and it is applied to the physical measurements. In addition, the spectroscopically based analogs to the LDR dosimetry parameters that are currently employed are detailed, as well as the development of the theory and measurement methods to arrive at these

Pre-equilibrium complex particle emission

International Nuclear Information System (INIS)

Bĕták, E.

2002-01-01

Semi-classical (phenomenological) pre-equilibrium emission of clusters of nucleons (complex particles) such as deuterons, tritons, helions and α particles from reactions induced by light projectiles (nucleons to α’s) is addressed. The main attention is given to the hard components in the emission energetic spectra, which play an increasing role at incident energies above 20 MeV, and are currently attributed to a presence of some kind of pre-equilibrium processes. In addition, the mechanisms of cluster reactions show special features such as the competition between pickup and knockout processes and the contributions of several successive steps in the reaction. The main frame used here to illustrate the processes and interplays of the competing mechanisms of pre-equilibrium cluster formation and emission, namely the coalescence, pick-up and knock-out, is the pre-equilibrium exciton model. It obviously contains the process of clusterization itself as its organic part. The most important case of complex particles with the largest amount of experimental data is that of alpha emission, which therefore naturally attracts most of the attention and where the widest range of possible mechanisms is available on the market. The loosely bound ejectiles, on the other side, are usually not able to demonstrate all features of the whole spectrum of contributing mechanisms, but they are nevertheless an important link between the nucleon emission and the cluster one.

Whole genome HBV deletion profiles and the accumulation of preS deletion mutant during antiviral treatment

Science.gov (United States)

2012-01-01

Background Hepatitis B virus (HBV), because of its error-prone viral polymerase, has a high mutation rate leading to widespread substitutions, deletions, and insertions in the HBV genome. Deletions may significantly change viral biological features complicating the progression of liver diseases. However, the clinical conditions correlating to the accumulation of deleted mutants remain unclear. In this study, we explored HBV deletion patterns and their association with disease status and antiviral treatment by performing whole genome sequencing on samples from 51 hepatitis B patients and by monitoring changes in deletion variants during treatment. Clone sequencing was used to analyze preS regions in another cohort of 52 patients. Results Among the core, preS, and basic core promoter (BCP) deletion hotspots, we identified preS to have the highest frequency and the most complex deletion pattern using whole genome sequencing. Further clone sequencing analysis on preS identified 70 deletions which were classified into 4 types, the most common being preS2. Also, in contrast to the core and BCP regions, most preS deletions were in-frame. Most deletions interrupted viral surface epitopes, and are possibly involved in evading immuno-surveillance. Among various clinical factors examined, logistic regression showed that antiviral medication affected the accumulation of deletion mutants (OR = 6.81, 95% CI = 1.296 ~ 35.817, P = 0.023). In chronic carriers of the virus, and individuals with chronic hepatitis, the deletion rate was significantly higher in the antiviral treatment group (Fisher exact test, P = 0.007). Particularly, preS2 deletions were associated with the usage of nucleos(t)ide analog therapy (Fisher exact test, P = 0.023). Dynamic increases in preS1 or preS2 deletions were also observed in quasispecies from samples taken from patients before and after three months of ADV therapy. In vitro experiments demonstrated that preS2 deletions alone

ON THE DEARTH OF COMPACT, MASSIVE, RED SEQUENCE GALAXIES IN THE LOCAL UNIVERSE

International Nuclear Information System (INIS)

Taylor, Edward N.; Franx, Marijn; Brinchmann, Jarle; Glazebrook, Karl; Van der Wel, Arjen; Van Dokkum, Pieter G

2010-01-01

We set out to test the claim that the recently identified population of compact, massive, and quiescent galaxies at z ∼ 2.3 must undergo significant size evolution to match the properties of galaxies found in the local universe. Using data from the Sloan Digital Sky Survey (SDSS; Data Release 7), we have conducted a search for local red sequence galaxies with sizes and masses comparable to those found at z ∼ 2.3. The SDSS spectroscopic target selection algorithm excludes high surface brightness objects; we show that this makes incompleteness a concern for such massive, compact galaxies, particularly for low redshifts (z ∼ * >10 10.7 M sun (∼5 x 10 10 M sun ) red sequence galaxies at 0.066 spec 5000. This result cannot be explained by incompleteness: in the 0.066 75% complete for galaxies with the sizes and masses seen at high redshift, although for the very smallest galaxies it may be as low as ∼20%. In order to confirm that the absence of such compact massive galaxies in SDSS is not produced by spectroscopic selection effects, we have also looked for such galaxies in the basic SDSS photometric catalog, using photometric redshifts. While we do find signs of a slight bias against massive, compact galaxies, this analysis suggests that the SDSS spectroscopic sample is missing at most a few objects in the regime we consider. Accepting the high-redshift results, it is clear that massive galaxies must undergo significant structural evolution over z ∼< 2 in order to match the population seen in the local universe. Our results suggest that a highly stochastic mechanism (e.g., major mergers) cannot be the primary driver of this strong size evolution.

The red deer Cervus elaphus genome CerEla1.0: sequencing, annotating, genes, and chromosomes.

Science.gov (United States)

Bana, Nóra Á; Nyiri, Anna; Nagy, János; Frank, Krisztián; Nagy, Tibor; Stéger, Viktor; Schiller, Mátyás; Lakatos, Péter; Sugár, László; Horn, Péter; Barta, Endre; Orosz, László

2018-01-02

We present here the de novo genome assembly CerEla1.0 for the red deer, Cervus elaphus, an emblematic member of the natural megafauna of the Northern Hemisphere. Humans spread the species in the South. Today, the red deer is also a farm-bred animal and is becoming a model animal in biomedical and population studies. Stag DNA was sequenced at 74× coverage by Illumina technology. The ALLPATHS-LG assembly of the reads resulted in 34.7 × 10 3 scaffolds, 26.1 × 10 3 of which were utilized in Cer.Ela1.0. The assembly spans 3.4 Gbp. For building the red deer pseudochromosomes, a pre-established genetic map was used for main anchor points. A nearly complete co-linearity was found between the mapmarker sequences of the deer genetic map and the order and orientation of the orthologous sequences in the syntenic bovine regions. Syntenies were also conserved at the in-scaffold level. The cM distances corresponded to 1.34 Mbp uniformly along the deer genome. Chromosomal rearrangements between deer and cattle were demonstrated. 2.8 × 10 6 SNPs, 365 × 10 3 indels and 19368 protein-coding genes were identified in CerEla1.0, along with positions for centromerons. CerEla1.0 demonstrates the utilization of dual references, i.e., when a target genome (here C. elaphus) already has a pre-established genetic map, and is combined with the well-established whole genome sequence of a closely related species (here Bos taurus). Genome-wide association studies (GWAS) that CerEla1.0 (NCBI, MKHE00000000) could serve for are discussed.

The evolution of stellar metallicity gradients of the Milky Way disk from LSS-GAC main sequence turn-off stars: a two-phase disk formation history?

International Nuclear Information System (INIS)

Xiang, Mao-Sheng; Liu, Xiao-Wei; Huang, Yang; Wang, Chun; Ren, Juan-Juan; Chen, Bing-Qiu; Sun, Ning-Chen; Zhang, Hua-Wei; Yuan, Hai-Bo; Rebassa-Mansergas, Alberto; Huo, Zhi-Ying

2015-01-01

Accurate measurements of stellar metallicity gradients in the radial and vertical directions of the disk and their temporal variations provide important constraints on the formation and evolution of the Milky Way disk. We use 297 042 main sequence turn-off stars selected from the LAMOST Spectroscopic Survey of the Galactic Anti-center (LSS-GAC) to determine the radial and vertical gradients of stellar metallicity, Δ[Fe/H]/ΔR and Δ[Fe/H]/Δ|Z| of the Milky Way disk in the direction of the anticenter. We determine ages of those turn-off stars by isochrone fitting and measure the temporal variations of metallicity gradients. We have carried out a detailed analysis of the selection effects resulting from the selection, observation and data reduction of LSS-GAC targets and the potential biases of a magnitude limited sample on the determinations of metallicity gradients. Our results show that the gradients, both in the radial and vertical directions, exhibit significant spatial and temporal variations. The radial gradients yielded by stars with the oldest ages (≳ 11 Gyr) are essentially zero at all heights from the disk midplane, while those given by younger stars are always negative. The vertical gradients deduced from stars with the oldest ages (≳ 11 Gyr) are negative and only show very weak variations with Galactocentric distance in the disk plane, R, while those yielded by younger stars show strong variations with R. After being essentially flat at the earliest epochs of disk formation, the radial gradients steepen as age decreases, reaching a maximum (steepest) at age 7–8 Gyr, and then they flatten again. Similar temporal trends are also found for the vertical gradients. We infer that the assembly of the Milky Way disk may have experienced at least two distinct phases. The earlier phase is probably related to a slow, pressure-supported collapse of gas, when the gas settles down to the disk mainly in the vertical direction. In the later phase, there are

Ultrafast Spectroscopic Noninvasive Probe of Vertical Carrier Transport in Heterostructure Devices

Science.gov (United States)

2016-03-01

ARL-TR-7618 ● MAR 2016 US Army Research Laboratory Ultrafast Spectroscopic Noninvasive Probe of Vertical Carrier Transport in...US Army Research Laboratory Ultrafast Spectroscopic Noninvasive Probe of Vertical Carrier Transport in Heterostructure Devices by Blair C...Spectroscopic Noninvasive Probe of Vertical Carrier Transport in Heterostructure Devices 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT

SPECTROSCOPIC ANALYSIS OF AN EIT WAVE/DIMMING OBSERVED BY HINODE/EIS

International Nuclear Information System (INIS)

Chen, F.; Ding, M. D.; Chen, P. F.

2010-01-01

EUV Imaging Telescope (EIT) waves are a wavelike phenomenon propagating outward from the coronal mass ejection source region, with expanding dimmings following behind. We present a spectroscopic study of an EIT wave/dimming event observed by the Hinode/Extreme-ultraviolet Imaging Spectrometer. Although the identification of the wave front is somewhat affected by the pre-existing loop structures, the expanding dimming is well defined. We investigate the line intensity, width, and Doppler velocity for four EUV lines. In addition to the significant blueshift implying plasma outflows in the dimming region as revealed in previous studies, we find that the widths of all four spectral lines increase at the outer edge of the dimmings. We illustrate that this feature can be well explained by the field line stretching model, which claims that EIT waves are apparently moving brightenings that are generated by the successive stretching of the closed field lines.

2-d spectroscopic imaging of brain tumours

International Nuclear Information System (INIS)

Ferris, N.J.; Brotchie, P.R.

2002-01-01

Full text: This poster illustrates the use of two-dimensional spectroscopic imaging (2-D SI) in the characterisation of brain tumours, and the monitoring of subsequent treatment. After conventional contrast-enhanced MR imaging of patients with known or suspected brain tumours, 2-D SI is performed at a single axial level. The level is chosen to include the maximum volume of abnormal enhancement, or, in non-enhancing lesions. The most extensive T2 signal abnormality. Two different MR systems have been used (Marconi Edge and GE Signa LX); at each site, a PRESS localisation sequence is employed with TE 128-144 ms. Automated software is used to generate spectral arrays, metabolite maps, and metabolite ratio maps from the spectroscopic data. Colour overlays of the maps onto anatomical images are produced using manufacturer software or the Medex imaging data analysis package. High grade gliomas showed choline levels higher than those in apparently normal brain, with decreases in NAA and creatine. Some lesions showed spectral abnormality extending into otherwise normal appearing brain. This was also seen in a case of CNS lymphoma. Lowgrade lesions showed choline levels similar to normal brain, but with decreased NAA. Only a small number of metastases have been studied, but to date no metastasis has shown spectral abnormality beyond the margins suggested by conventional imaging. Follow-up studies generally show spectral heterogeneity. Regions with choline levels higher than those in normal-appearing brain are considered to represent recurrent high-grade tumour. Some regions show choline to be the dominant metabolite, but its level is not greater than that seen in normal brain. These regions are considered suspicious for residual / recurrent tumour when the choline / creatine ratio exceeds 2 (lower ratios may represent treatment effect). 2-D SI improves the initial assessment of brain tumours, and has potential for influencing the radiotherapy treatment strategy. 2-D SI also

Pyrene conjugation and spectroscopic analysis of hydroxypropyl methylcellulose compounds successfully demonstrated a local dielectric difference associated with in vivo anti-prion activity.

Directory of Open Access Journals (Sweden)

Kenta Teruya

Full Text Available Our previous study on prion-infected rodents revealed that hydroxypropyl methylcellulose compounds (HPMCs with different molecular weights but similar composition and degree of substitution have different levels of long-lasting anti-prion activity. In this study, we searched these HPMCs for a parameter specifically associated with in vivo anti-prion activity by analyzing in vitro chemical properties and in vivo tissue distributions. Infrared spectroscopic and thermal analyses revealed no differences among HPMCs, whereas pyrene conjugation and spectroscopic analysis revealed that the fluorescence intensity ratio of peak III/peak I correlated with anti-prion activity. This correlation was more clearly demonstrated in the anti-prion activity of the 1-year pre-infection treatment than that of the immediate post-infection treatment. In addition, the intensity ratio of peak III/peak I negatively correlated with the macrophage uptake level of HPMCs in our previous study. However, the in vivo distribution pattern was apparently not associated with anti-prion activity and was different in the representative tissues. These findings suggest that pyrene conjugation and spectroscopic analysis are powerful methods to successfully demonstrate local dielectric differences in HPMCs and provide a feasible parameter denoting the long-lasting anti-prion activity of HPMCs in vivo.

Fotometría infrarroja del Reloj de Arena en M8

Science.gov (United States)

Arias, J.; Barbá, R.; Morrell, N.; Rubio, M.

We present sub-arcsecond resolution JHKs imaging of the Hourglass Nebula in Messier 8, obtained with the 2.5-m du Pont telescope at Las Campanas Observatory (LCO), Chile. Near-infrared colors have been measured for numerous infrared sources around the O-type star Herschel 36 (O7 V), the brightest source in the field and main responsible for the nebula ionization. Several of those IR sources are identified as Hα emission stars from narrow-band Hubble Space Telescope images, and some of them display a knotty shape, characteristic of proplyd-like objects. Based on the NIR color-color and color-magnitude diagrams, we also identified dozens of NIR excess sources which %we selected as are prime candidates to be intermediate and low-mass pre-main-sequence stars. Additionally, we present preliminary results of the spectroscopic confirmation of some T Tauri stars among these objects, based on spectra recently obtained with the 6.5-m Magellan telescope at LCO.

THE TIME-DOMAIN SPECTROSCOPIC SURVEY: UNDERSTANDING THE OPTICALLY VARIABLE SKY WITH SEQUELS IN SDSS-III

International Nuclear Information System (INIS)

Ruan, John J.; Anderson, Scott F.; Davenport, James R. A.; Green, Paul J.; Morganson, Eric; Eracleous, Michael; Brandt, William N.; Myers, Adam D.; Badenes, Carles; Bershady, Matthew A.; Chambers, Kenneth C.; Flewelling, Heather; Kaiser, Nick; Dawson, Kyle S.; Heckman, Timothy M.; Isler, Jedidah C.; Kneib, Jean-Paul; MacLeod, Chelsea L.; Ross, Nicholas P.; Paris, Isabelle

2016-01-01

The Time-Domain Spectroscopic Survey (TDSS) is an SDSS-IV eBOSS subproject primarily aimed at obtaining identification spectra of ∼220,000 optically variable objects systematically selected from SDSS/Pan-STARRS1 multi-epoch imaging. We present a preview of the science enabled by TDSS, based on TDSS spectra taken over ∼320 deg 2 of sky as part of the SEQUELS survey in SDSS-III, which is in part a pilot survey for eBOSS in SDSS-IV. Using the 15,746 TDSS-selected single-epoch spectra of photometrically variable objects in SEQUELS, we determine the demographics of our variability-selected sample and investigate the unique spectral characteristics inherent in samples selected by variability. We show that variability-based selection of quasars complements color-based selection by selecting additional redder quasars and mitigates redshift biases to produce a smooth quasar redshift distribution over a wide range of redshifts. The resulting quasar sample contains systematically higher fractions of blazars and broad absorption line quasars than from color-selected samples. Similarly, we show that M dwarfs in the TDSS-selected stellar sample have systematically higher chromospheric active fractions than the underlying M-dwarf population based on their H α emission. TDSS also contains a large number of RR Lyrae and eclipsing binary stars with main-sequence colors, including a few composite-spectrum binaries. Finally, our visual inspection of TDSS spectra uncovers a significant number of peculiar spectra, and we highlight a few cases of these interesting objects. With a factor of ∼15 more spectra, the main TDSS survey in SDSS-IV will leverage the lessons learned from these early results for a variety of time-domain science applications.

Modelling auto ignition of hydrogen in a jet ignition pre-chamber

Energy Technology Data Exchange (ETDEWEB)

Boretti, Alberto A. [School of Science and Engineering, University of Ballarat, PO Box 663, Ballarat, Victoria 3353 (Australia)

2010-04-15

Spark-less jet ignition pre-chambers are enablers of high efficiencies and load control by quantity of fuel injected when coupled with direct injection of main chamber fuel, thus permitting always lean burn bulk stratified combustion. Towards the end of the compression stroke, a small quantity of hydrogen is injected within the pre-chamber, where it mixes with the air entering from the main chamber. Combustion of the air and fuel mixture then starts within the pre-chamber because of the high temperature of the hot glow plug, and then jets of partially combusted hot gases enter the main chamber igniting there in the bulk, over multiple ignition points, lean stratified mixtures of air and fuel. The paper describes the operation of the spark-less jet ignition pre-chamber coupling CFD and CAE engine simulations to allow component selection and engine performance evaluation. (author)

Prediction of novel pre-microRNAs with high accuracy through boosting and SVM.

Science.gov (United States)

Zhang, Yuanwei; Yang, Yifan; Zhang, Huan; Jiang, Xiaohua; Xu, Bo; Xue, Yu; Cao, Yunxia; Zhai, Qian; Zhai, Yong; Xu, Mingqing; Cooke, Howard J; Shi, Qinghua

2011-05-15

High-throughput deep-sequencing technology has generated an unprecedented number of expressed short sequence reads, presenting not only an opportunity but also a challenge for prediction of novel microRNAs. To verify the existence of candidate microRNAs, we have to show that these short sequences can be processed from candidate pre-microRNAs. However, it is laborious and time consuming to verify these using existing experimental techniques. Therefore, here, we describe a new method, miRD, which is constructed using two feature selection strategies based on support vector machines (SVMs) and boosting method. It is a high-efficiency tool for novel pre-microRNA prediction with accuracy up to 94.0% among different species. miRD is implemented in PHP/PERL+MySQL+R and can be freely accessed at http://mcg.ustc.edu.cn/rpg/mird/mird.php.

A Pre-Bridge Course: The Natural Role of Sequences and Series

Science.gov (United States)

Beaver, Scott

2011-01-01

The Sequences and Series calculus course (S&S) can be structured to provide students with a unique opportunity to build their proofs skills prior to or concurrently with a bridge course. This article offers a framework for S&S which places logical reasoning on equal footing with content, by employing the theorems and convergence tests as axioms,…

On determining dose rate constants spectroscopically

International Nuclear Information System (INIS)

Rodriguez, M.; Rogers, D. W. O.

2013-01-01

Purpose: To investigate several aspects of the Chen and Nath spectroscopic method of determining the dose rate constants of 125 I and 103 Pd seeds [Z. Chen and R. Nath, Phys. Med. Biol. 55, 6089–6104 (2010)] including the accuracy of using a line or dual-point source approximation as done in their method, and the accuracy of ignoring the effects of the scattered photons in the spectra. Additionally, the authors investigate the accuracy of the literature's many different spectra for bare, i.e., unencapsulated 125 I and 103 Pd sources. Methods: Spectra generated by 14 125 I and 6 103 Pd seeds were calculated in vacuo at 10 cm from the source in a 2.7 × 2.7 × 0.05 cm 3 voxel using the EGSnrc BrachyDose Monte Carlo code. Calculated spectra used the initial photon spectra recommended by AAPM's TG-43U1 and NCRP (National Council of Radiation Protection and Measurements) Report 58 for the 125 I seeds, or TG-43U1 and NNDC(2000) (National Nuclear Data Center, 2000) for 103 Pd seeds. The emitted spectra were treated as coming from a line or dual-point source in a Monte Carlo simulation to calculate the dose rate constant. The TG-43U1 definition of the dose rate constant was used. These calculations were performed using the full spectrum including scattered photons or using only the main peaks in the spectrum as done experimentally. Statistical uncertainties on the air kerma/history and the dose rate/history were ⩽0.2%. The dose rate constants were also calculated using Monte Carlo simulations of the full seed model. Results: The ratio of the intensity of the 31 keV line relative to that of the main peak in 125 I spectra is, on average, 6.8% higher when calculated with the NCRP Report 58 initial spectrum vs that calculated with TG-43U1 initial spectrum. The 103 Pd spectra exhibit an average 6.2% decrease in the 22.9 keV line relative to the main peak when calculated with the TG-43U1 rather than the NNDC(2000) initial spectrum. The measured values from three different

A two-stage stochastic rule-based model to determine pre-assembly buffer content

Science.gov (United States)

Gunay, Elif Elcin; Kula, Ufuk

2018-01-01

This study considers instant decision-making needs of the automobile manufactures for resequencing vehicles before final assembly (FA). We propose a rule-based two-stage stochastic model to determine the number of spare vehicles that should be kept in the pre-assembly buffer to restore the altered sequence due to paint defects and upstream department constraints. First stage of the model decides the spare vehicle quantities, where the second stage model recovers the scrambled sequence respect to pre-defined rules. The problem is solved by sample average approximation (SAA) algorithm. We conduct a numerical study to compare the solutions of heuristic model with optimal ones and provide following insights: (i) as the mismatch between paint entrance and scheduled sequence decreases, the rule-based heuristic model recovers the scrambled sequence as good as the optimal resequencing model, (ii) the rule-based model is more sensitive to the mismatch between the paint entrance and scheduled sequences for recovering the scrambled sequence, (iii) as the defect rate increases, the difference in recovery effectiveness between rule-based heuristic and optimal solutions increases, (iv) as buffer capacity increases, the recovery effectiveness of the optimization model outperforms heuristic model, (v) as expected the rule-based model holds more inventory than the optimization model.

The RNA world, automatic sequences and oncogenetics

Energy Technology Data Exchange (ETDEWEB)

Tahir Shah, K

1993-04-01

We construct a model of the RNA world in terms of naturally evolving nucleotide sequences assuming only Crick-Watson base pairing and self-cleaving/splicing capability. These sequences have the following properties. (1) They are recognizable by an automation (or automata). That is, to each k-sequence, there exist a k-automation which accepts, recognizes or generates the k-sequence. These are known as automatic sequences. Fibonacci and Morse-Thue sequences are the most natural outcome of pre-biotic chemical conditions. (2) Infinite (resp. large) sequences are self-similar (resp. nearly self-similar) under certain rewrite rules and consequently give rise to fractal (resp.fractal-like) structures. Computationally, such sequences can also be generated by their corresponding deterministic parallel re-write system, known as a DOL system. The self-similar sequences are fixed points of their respective rewrite rules. Some of these automatic sequences have the capability that they can read or ``accept`` other sequences while others can detect errors and trigger error-correcting mechanisms. They can be enlarged and have block and/or palindrome structure. Linear recurring sequences such as Fibonacci sequence are simply Feed-back Shift Registers, a well know model of information processing machines. We show that a mutation of any rewrite rule can cause a combinatorial explosion of error and relates this to oncogenetical behavior. On the other hand, a mutation of sequences that are not rewrite rules, leads to normal evolutionary change. Known experimental results support our hypothesis. (author). Refs.

The RNA world, automatic sequences and oncogenetics

International Nuclear Information System (INIS)

Tahir Shah, K.

1993-04-01

We construct a model of the RNA world in terms of naturally evolving nucleotide sequences assuming only Crick-Watson base pairing and self-cleaving/splicing capability. These sequences have the following properties. 1) They are recognizable by an automation (or automata). That is, to each k-sequence, there exist a k-automation which accepts, recognizes or generates the k-sequence. These are known as automatic sequences. Fibonacci and Morse-Thue sequences are the most natural outcome of pre-biotic chemical conditions. 2) Infinite (resp. large) sequences are self-similar (resp. nearly self-similar) under certain rewrite rules and consequently give rise to fractal (resp.fractal-like) structures. Computationally, such sequences can also be generated by their corresponding deterministic parallel re-write system, known as a DOL system. The self-similar sequences are fixed points of their respective rewrite rules. Some of these automatic sequences have the capability that they can read or 'accept' other sequences while others can detect errors and trigger error-correcting mechanisms. They can be enlarged and have block and/or palindrome structure. Linear recurring sequences such as Fibonacci sequence are simply Feed-back Shift Registers, a well know model of information processing machines. We show that a mutation of any rewrite rule can cause a combinatorial explosion of error and relates this to oncogenetical behavior. On the other hand, a mutation of sequences that are not rewrite rules, leads to normal evolutionary change. Known experimental results support our hypothesis. (author). Refs

Previously unclassified bacteria dominate during thermophilic and mesophilic anaerobic pre-treatment of primary sludge.

Science.gov (United States)

Pervin, Hasina M; Batstone, Damien J; Bond, Philip L

2013-06-01

Thermophilic biological pre-treatment enables enhanced anaerobic digestion for treatment of wastewater sludges but, at present, there is limited understanding of the hydrolytic-acidogenic microbial composition and its contribution to this process. In this study, the process was assessed by comparing the microbiology of thermophilic (50-65 °C) and mesophilic (35 °C) pre-treatment reactors treating primary sludge. A full-cycle approach for the 16S rRNA genes was applied in order to monitor the diversity of bacteria and their abundance in a thermophilic pre-treatment reactor treating primary sludge. For the thermophilic pre-treatment (TP), over 90% of the sequences were previously undetected and these had less than 97% sequence similarity to cultured organisms. During the first 83 days, members of the Betaproteobacteria dominated the community sequences and a newly designed probe was used to monitor a previously unknown bacterium affiliated with the genus Brachymonas. Between days 85 and 183, three phylotypes that affiliated with the genera Comamonas, Clostridium and Lysobacter were persistently dominant in the TP community, as revealed by terminal-restriction fragment length polymorphism (T-RFLP). Hydrolytic and fermentative functions have been speculated for these bacteria. Mesophilic pre-treatment (MP) and TP communities were different but they were both relatively dynamic. Statistical correlation analysis and the function of closely allied reference organisms indicated that previously unclassified bacteria dominated the TP community and may have been functionally involved in the enhanced hydrolytic performance of thermophilic anaerobic pre-treatment. This study is the first to reveal the diversity and dynamics of bacteria during anaerobic digestion of primary sludge. Copyright © 2013 Elsevier GmbH. All rights reserved.

Spectroscopic and imaging diagnostics of pulsed laser deposition laser plasmas

International Nuclear Information System (INIS)

Thareja, Raj K.

2002-01-01

An overview of laser spectroscopic techniques used in the diagnostics of laser ablated plumes used for thin film deposition is given. An emerging laser spectroscopic imaging technique for the laser ablation material processing is discussed. (author)

Sequence Capture and Phylogenetic Utility of Genomic Ultraconserved Elements Obtained from Pinned Insect Specimens.

Directory of Open Access Journals (Sweden)

Bonnie B Blaimer

Full Text Available Obtaining sequence data from historical museum specimens has been a growing research interest, invigorated by next-generation sequencing methods that allow inputs of highly degraded DNA. We applied a target enrichment and next-generation sequencing protocol to generate ultraconserved elements (UCEs from 51 large carpenter bee specimens (genus Xylocopa, representing 25 species with specimen ages ranging from 2-121 years. We measured the correlation between specimen age and DNA yield (pre- and post-library preparation DNA concentration and several UCE sequence capture statistics (raw read count, UCE reads on target, UCE mean contig length and UCE locus count with linear regression models. We performed piecewise regression to test for specific breakpoints in the relationship of specimen age and DNA yield and sequence capture variables. Additionally, we compared UCE data from newer and older specimens of the same species and reconstructed their phylogeny in order to confirm the validity of our data. We recovered 6-972 UCE loci from samples with pre-library DNA concentrations ranging from 0.06-9.8 ng/μL. All investigated DNA yield and sequence capture variables were significantly but only moderately negatively correlated with specimen age. Specimens of age 20 years or less had significantly higher pre- and post-library concentrations, UCE contig lengths, and locus counts compared to specimens older than 20 years. We found breakpoints in our data indicating a decrease of the initial detrimental effect of specimen age on pre- and post-library DNA concentration and UCE contig length starting around 21-39 years after preservation. Our phylogenetic results confirmed the integrity of our data, giving preliminary insights into relationships within Xylocopa. We consider the effect of additional factors not measured in this study on our age-related sequence capture results, such as DNA fragmentation and preservation method, and discuss the promise of the UCE

Spectroscopic study of silicate glass structure. Application to the case of iron and magnesium

International Nuclear Information System (INIS)

Rossano, Stephanie

2008-01-01

During the last 10 years, I focused my research topics on silicate glass structure. More specifically I have been interested by two main components of natural and technological silicate glasses, Fe and Mg. Using solid state spectroscopic methods adapted to the disordered nature of glass coupled to molecular dynamics simulation and modeling or ab initio calculation, I have studied the environment of iron and magnesium and their impact on glass properties. Information on the distribution of environments in glasses have been extracted. (author)

When technological affordances meet interactional norms: the value of pre-screening in online chat counseling

NARCIS (Netherlands)

Stommel, Wyke; te Molder, Hedwig Frederica Maria

2016-01-01

We present a conversation analysis of openings sequences of online text-based chat counseling. Particular about this chat counseling is that the clients made available their help question through pre-screening. The data consisted of 40 chat sessions with pre-screening and 34 sessions without

High Class-Imbalance in pre-miRNA Prediction: A Novel Approach Based on deepSOM.

Science.gov (United States)

Stegmayer, Georgina; Yones, Cristian; Kamenetzky, Laura; Milone, Diego H

2017-01-01

The computational prediction of novel microRNA within a full genome involves identifying sequences having the highest chance of being a miRNA precursor (pre-miRNA). These sequences are usually named candidates to miRNA. The well-known pre-miRNAs are usually only a few in comparison to the hundreds of thousands of potential candidates to miRNA that have to be analyzed, which makes this task a high class-imbalance classification problem. The classical way of approaching it has been training a binary classifier in a supervised manner, using well-known pre-miRNAs as positive class and artificially defining the negative class. However, although the selection of positive labeled examples is straightforward, it is very difficult to build a set of negative examples in order to obtain a good set of training samples for a supervised method. In this work, we propose a novel and effective way of approaching this problem using machine learning, without the definition of negative examples. The proposal is based on clustering unlabeled sequences of a genome together with well-known miRNA precursors for the organism under study, which allows for the quick identification of the best candidates to miRNA as those sequences clustered with known precursors. Furthermore, we propose a deep model to overcome the problem of having very few positive class labels. They are always maintained in the deep levels as positive class while less likely pre-miRNA sequences are filtered level after level. Our approach has been compared with other methods for pre-miRNAs prediction in several species, showing effective predictivity of novel miRNAs. Additionally, we will show that our approach has a lower training time and allows for a better graphical navegability and interpretation of the results. A web-demo interface to try deepSOM is available at http://fich.unl.edu.ar/sinc/web-demo/deepsom/.

Microbial survey of ready-to-eat salad ingredients sold at retail reveals the occurrence and the persistence of Listeria monocytogenes Sequence Types 2 and 87 in pre-packed smoked salmon.

Science.gov (United States)

Chau, Man Ling; Aung, Kyaw Thu; Hapuarachchi, Hapuarachchige Chanditha; Lee, Pei Sze Valarie; Lim, Pei Ying; Kang, Joanne Su Lin; Ng, Youming; Yap, Hooi Ming; Yuk, Hyun-Gyun; Gutiérrez, Ramona Alikiiteaga; Ng, Lee Ching

2017-02-28

As the preparation of salads involves extensive handling and the use of uncooked ingredients, they are particularly vulnerable to microbial contamination. This study aimed to determine the microbial safety and quality of pre-packed salads and salad bar ingredients sold in Singapore, so as to identify public health risks that could arise from consuming salads and to determine areas for improvement in the management of food safety. The most frequently encountered organism in pre-packed salad samples was B. cereus, particularly in pasta salads (33.3%, 10/30). The most commonly detected organism in salad bar ingredients was L. monocytogenes, in particular seafood ingredients (44.1%, 15/34), largely due to contaminated smoked salmon. Further investigation showed that 21.6% (37/171) of the pre-packed smoked salmon sold in supermarkets contained L. monocytogenes. Significantly higher prevalence of L. monocytogenes and higher Standard Plate Count were detected in smoked salmon at salad bars compared to pre-packed smoked salmon in supermarkets, which suggested multiplication of the organism as the products move down the supply chain. Further molecular analysis revealed that L. monocytogenes Sequence Type (ST) 2 and ST87 were present in a particular brand of pre-packed salmon products over a 4-year period, implying a potential persistent contamination problem at the manufacturing level. Our findings highlighted a need to improve manufacturing and retail hygiene processes as well as to educate vulnerable populations to avoid consuming food prone to L. monocytogenes contamination.

Obtaining the Electron Angular Momentum Coupling Spectroscopic Terms, jj

Science.gov (United States)

Orofino, Hugo; Faria, Roberto B.

2010-01-01

A systematic procedure is developed to obtain the electron angular momentum coupling (jj) spectroscopic terms, which is based on building microstates in which each individual electron is placed in a different m[subscript j] "orbital". This approach is similar to that used to obtain the spectroscopic terms under the Russell-Saunders (LS) coupling…

Photometric and spectroscopic variability of the B5IIIe star HD 171219

Science.gov (United States)

Andrade, L.; Janot-Pacheco, E.; Emilio, M.; Frémat, Y.; Neiner, C.; Poretti, E.; Mathias, P.; Rainer, M.; Suárez, J. C.; Uytterhoeven, K.; Briquet, M.; Diago, P. D.; Fabregat, J.; Gutiérrez-Soto, J.

2017-07-01

We analyzed the star HD 171219, one of the relatively bright Be stars observed in the seismo field of the CoRoT satellite, in order to determine its physical and pulsation characteristics. Classical Be stars are main-sequence objects of mainly B-type, whose spectra show, or have shown at some epoch, Balmer lines in emission and an infrared excess. Both characteristics are attributed to an equatorially concentrated circumstellar disk fed by non-periodic mass-loss episodes (outbursts). Be stars often show nonradial pulsation gravity modes and, as more recently discovered, stochastically excited oscillations. Applying the CLEANEST algorithm to the high-cadence and highly photometrically precise measurements of the HD 171219 light curve led us to perform an unprecedented detailed analysis of its nonradial pulsations. Tens of frequencies have been detected in the object compatible with nonradial g-modes. Additional high-resolution ground-based spectroscopic observations were obtained at La Silla (HARPS) and Haute Provence (SOPHIE) observatories during the month preceding CoRoT observations. Additional information was obtained from low-resolution spectra from the BeSS database. From spectral line fitting we determined physical parameters of the star, which is seen equator-on (I = 90°). We also found in the ground data the same frequencies as in CoRoT data. Additionally, we analyzed the circumstellar activity through the traditional method of violet to red emission Hα line variation. A quintuplet was identified at approximately 1.113 c d-1 (12.88 μHz) with a separation of 0.017 c d-1 that can be attributed to a pulsation degree ℓ 2. The light curve shows six small- to medium-scale outbursts during the CoRoT observations. The intensity of the main frequencies varies after each outburst, suggesting a possible correlation between the nonradial pulsations regime and the feeding of the envelope. The CoRoT space mission was developed and operated by the French space agency

Lithium abundances for 185 main-sequence stars: Galactic evolution and stellar depletion of lithium

Science.gov (United States)

Chen, Y. Q.; Nissen, P. E.; Benoni, T.; Zhao, G.

2001-06-01

We present a survey of lithium abundances in 185 main-sequence field stars with 5600 interesting result from this study is the presence of a large gap in the log varepsilon (Li) - Teff plane, which distinguishes ``Li-dip'' stars like those first identified in the Hyades cluster by Boesgaard & Tripicco (\\cite{Boesgaard86}) from other stars with a much higher Li abundance. The Li-dip stars concentrate on a certain mass, which decreases with metallicity from about 1.4 Msun at solar metallicity to 1.1 Msun at [Fe/H] =~ -1.0. Excluding the Li-dip stars and a small group of lower mass stars with Teff rate of angular momentum loss. It cannot be excluded, however, that a cosmic scatter of the Li abundance in the Galaxy at a given metallicity contributes to the dispersion in Li abundance. These problems make it difficult to determine the Galactic evolution of Li from the data, but a comparison of the upper envelope of the distribution of stars in the log varepsilon (Li) - [Fe/H] plane with recent Galactic evolutionary models by Romano et al. (\\cite{Romano99}) suggests that novae are a major source for the Li production in the Galactic disk; their occurrence seems to be the explanation for the steep increase of Li abundance at [Fe/H] =~ -0.4. Based on observations carried out at Beijing Astronomical Observatory (Xinglong, PR China) and European Southern Observatory, La Silla, Chile. Table 1 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/371/943 and at http://www.edpsciences.org

On the Use of the Main-sequence Knee (Saddle) to Measure Globular Cluster Ages

Science.gov (United States)

Saracino, S.; Dalessandro, E.; Ferraro, F. R.; Lanzoni, B.; Origlia, L.; Salaris, M.; Pietrinferni, A.; Geisler, D.; Kalirai, J. S.; Correnti, M.; Cohen, R. E.; Mauro, F.; Villanova, S.; Moni Bidin, C.

2018-06-01

In this paper, we review the operational definition of the so-called main-sequence knee (MS-knee), a feature in the color-magnitude diagram (CMD) occurring at the low-mass end of the MS. The magnitude of this feature is predicted to be independent of age at fixed chemical composition. For this reason, its difference in magnitude with respect to the MS turn-off (MS-TO) point has been suggested as a possible diagnostic to estimate absolute globular cluster (GC) ages. We first demonstrate that the operational definition of the MS-knee currently adopted in the literature refers to the inflection point of the MS (which we here more appropriately named MS-saddle), a feature that is well distinct from the knee and which cannot be used as its proxy. The MS-knee is only visible in near-infrared CMDs, while the MS-saddle can be also detected in optical–NIR CMDs. By using different sets of isochrones, we then demonstrate that the absolute magnitude of the MS-knee varies by a few tenths of a dex from one model to another, thus showing that at the moment stellar models may not capture the full systematic error in the method. We also demonstrate that while the absolute magnitude of the MS-saddle is almost coincident in different models, it has a systematic dependence on the adopted color combinations which is not predicted by stellar models. Hence, it cannot be used as a reliable reference for absolute age determination. Moreover, when statistical and systematic uncertainties are properly taken into account, the difference in magnitude between the MS-TO and the MS-saddle does not provide absolute ages with better accuracy than other methods like the MS-fitting.

Interaction of methotrexate with trypsin analyzed by spectroscopic and molecular modeling methods

Science.gov (United States)

Wang, Yanqing; Zhang, Hongmei; Cao, Jian; Zhou, Qiuhua

2013-11-01

Trypsin is one of important digestive enzymes that have intimate correlation with human health and illness. In this work, the interaction of trypsin with methotrexate was investigated by spectroscopic and molecular modeling methods. The results revealed that methotrexate could interact with trypsin with about one binding site. Methotrexate molecule could enter into the primary substrate-binding pocket, resulting in inhibition of trypsin activity. Furthermore, the thermodynamic analysis implied that electrostatic force, hydrogen bonding, van der Waals and hydrophobic interactions were the main interactions for stabilizing the trypsin-methotrexate system, which agreed well with the results from the molecular modeling study.

Pre-reading activities in EFL/ESL reading textbooks and Turkish preparatory school teachers' attitudes toward pre-reading activities

OpenAIRE

Jecksembieyva, Nurgaisha

1993-01-01

Ankara : Faculty of Humanities and Letters and the Institute of Economics and Social Sciences of Bilkent University, 1993. Thesis (Master's) -- -Bilkent University, 1993. Includes bibliographical references leaves 35-40. The main focus of this study was to investigate pre-reading activities in EFL/ESL reading textbooks and to determine teachers' attitudes toward pre-reading activities. Fifteen reading textbooks for EFL/ESL students for different proficiency levels (beginning, interm...

Spectroscopic properties of tetravalent actinide ions in solids

International Nuclear Information System (INIS)

Krupa, J.C.

1987-01-01

Optical spectroscopy is a powerful tool to study the electronic structure of an optically active transition ion in the condensed phase media and consequently to study the interactions between the central ion and its environment. The main interactions that are essential for an understanding of the energy level distribution of an f N ion in solids is briefly examined and the deduced free-ion and crystal field parameters for Pa 4+ , U 4+ , Np 4+ are compared to those of the isoelectronic configuration lanthanide ions. At last, the actinide series offers an interesting situation since the 5f electrons in the metals are delocalized in the light actinides and then localized, that sould affect the nature of the chemical bonding in the two parts of the series. Is this trend reflected in the An 4+ spectroscopic parameters

Iterative estimation of the background in noisy spectroscopic data

International Nuclear Information System (INIS)

Zhu, M.H.; Liu, L.G.; Cheng, Y.S.; Dong, T.K.; You, Z.; Xu, A.A.

2009-01-01

In this paper, we present an iterative filtering method to estimate the background of noisy spectroscopic data. The proposed method avoids the calculation of the average full width at half maximum (FWHM) of the whole spectrum and the peak regions, and it can estimate the background efficiently, especially for spectroscopic data with the Compton continuum.

Spectroscopic databases - A tool for structure elucidation

Energy Technology Data Exchange (ETDEWEB)

Luksch, P [Fachinformationszentrum Karlsruhe, Gesellschaft fuer Wissenschaftlich-Technische Information mbH, Eggenstein-Leopoldshafen (Germany)

1990-05-01

Spectroscopic databases have developed to useful tools in the process of structure elucidation. Besides the conventional library searches, new intelligent programs have been added, that are able to predict structural features from measured spectra or to simulate for a given structure. The example of the C13NMR/IR database developed at BASF and available on STN is used to illustrate the present capabilities of online database. New developments in the field of spectrum simulation and methods for the prediction of complete structures from spectroscopic information are reviewed. (author). 10 refs, 5 figs.

Reproducibility of P-31 spectroscopic imaging of normal human myocardium

International Nuclear Information System (INIS)

Tavares, N.J.; Chew, W.; Auffermann, W.; Higgins, C.B.

1988-01-01

To assess reproducibility of P-31 MR spectroscopy of human myocardium, ten normal male volunteers were studied on two separate occasions. Spectra were acquired on a clinical 1.5-T MR imaging unit (Signa, General Electric) using a one-dimensional gated spectroscopic imaging sequence (matrix size, 32 X 256) over 20 minutes. Peaks in the adenosine triphosphate (ATP) region, phosphocreatine (PCR), phosphodiesters (PD), and peaks attributable to 2,3 diphosphoglycerate from blood were observed. Interindividual and intraindividual variability expressed as standard errors of the mean (mean +- SEM) were 1.54 +- 0.04 (variability among subjects) and 0.04 (variability between first and second studies) for PCR/β ATP; 0.97 +- 0.18 and 0.06 for PD/β ATP; and 0.62 +- 0.10 and 0.05 for PD/PCR, respectively. In conclusion, P-31 MR spectroscopy yields consistent and reproducible myocardial spectra that might be useful in the future for the evaluation and monitoring of cardiac disease

DIARRHEA IN CHILDREN: MAIN CAUSES AND WAYS OF TREATMENT

Directory of Open Access Journals (Sweden)

S.V. Bel’mer

2010-01-01

Full Text Available The article discusses main questions of diagnostics of diarrhea in children. Main cause of acute diarrhea is infection, mainly viral (rotavirus, etc.. Chronic diarrhea frequently has non-infectious origin. The need of multi-aspect diagnostics of diarrhea cause in children is related to the significance of treatment of main disease. Besides, treatment of chronic and acute diarrhea include major component: adsorbents based on smectite. In total treatment of diarrhea has to be complex with the use of dietotherapy and medications: mucocytoprotectors, regulators of motoric, pre- and probiotics.Key words: children, diarrhea, treatment.(Voprosy sovremennoi pediatrii — Current Pediatrics. 2010;9(6:135-138

Analysis of transfer reactions: determination of spectroscopic factors

Energy Technology Data Exchange (ETDEWEB)

Keeley, N. [CEA Saclay, Dept. d' Astrophysique, de Physique des Particules de Physique Nucleaire et de l' Instrumentation Associee (DSM/DAPNIA/SPhN), 91- Gif sur Yvette (France); The Andrzej So an Institute for Nuclear Studies, Dept. of Nuclear Reactions, Warsaw (Poland)

2007-07-01

An overview of the most popular models used for the analysis of direct reaction data is given, concentrating on practical aspects. The 4 following models (in order of increasing sophistication): the distorted wave born approximation (DWBA), the adiabatic model, the coupled channels born approximation, and the coupled reaction channels are briefly described. As a concrete example, the C{sup 12}(d,p)C{sup 13} reaction at an incident deuteron energy of 30 MeV is analysed with progressively more physically sophisticated models. The effect of the choice of the reaction model on the spectroscopic information extracted from the data is investigated and other sources of uncertainty in the derived spectroscopic factors are discussed. We have showed that the choice of the reaction model can significantly influence the nuclear structure information, particularly the spectroscopic factors or amplitudes but occasionally also the spin-parity, that we wish to extract from direct reaction data. We have also demonstrated that the DWBA can fail to give a satisfactory description of transfer data but when the tenets of the theory are fulfilled DWBA can work very well and will yield the same results as most sophisticated models. The use of global rather than fitted optical potentials can also lead to important differences in the extracted spectroscopic factors.

Multilocus Sequence Analysis and rpoB Sequencing of Mycobacterium abscessus (Sensu Lato) Strains▿

Science.gov (United States)

Macheras, Edouard; Roux, Anne-Laure; Bastian, Sylvaine; Leão, Sylvia Cardoso; Palaci, Moises; Sivadon-Tardy, Valérie; Gutierrez, Cristina; Richter, Elvira; Rüsch-Gerdes, Sabine; Pfyffer, Gaby; Bodmer, Thomas; Cambau, Emmanuelle; Gaillard, Jean-Louis; Heym, Beate

2011-01-01

Mycobacterium abscessus, Mycobacterium bolletii, and Mycobacterium massiliense (Mycobacterium abscessus sensu lato) are closely related species that currently are identified by the sequencing of the rpoB gene. However, recent studies show that rpoB sequencing alone is insufficient to discriminate between these species, and some authors have questioned their current taxonomic classification. We studied here a large collection of M. abscessus (sensu lato) strains by partial rpoB sequencing (752 bp) and multilocus sequence analysis (MLSA). The final MLSA scheme developed was based on the partial sequences of eight housekeeping genes: argH, cya, glpK, gnd, murC, pgm, pta, and purH. The strains studied included the three type strains (M. abscessus CIP 104536T, M. massiliense CIP 108297T, and M. bolletii CIP 108541T) and 120 isolates recovered between 1997 and 2007 in France, Germany, Switzerland, and Brazil. The rpoB phylogenetic tree confirmed the existence of three main clusters, each comprising the type strain of one species. However, divergence values between the M. massiliense and M. bolletii clusters all were below 3% and between the M. abscessus and M. massiliense clusters were from 2.66 to 3.59%. The tree produced using the concatenated MLSA gene sequences (4,071 bp) also showed three main clusters, each comprising the type strain of one species. The M. abscessus cluster had a bootstrap value of 100% and was mostly compact. Bootstrap values for the M. massiliense and M. bolletii branches were much lower (71 and 61%, respectively), with the M. massiliense cluster having a fuzzy aspect. Mean (range) divergence values were 2.17% (1.13 to 2.58%) between the M. abscessus and M. massiliense clusters, 2.37% (1.5 to 2.85%) between the M. abscessus and M. bolletii clusters, and 2.28% (0.86 to 2.68%) between the M. massiliense and M. bolletii clusters. Adding the rpoB sequence to the MLSA-concatenated sequence (total sequence, 4,823 bp) had little effect on the clustering

Multilocus sequence analysis and rpoB sequencing of Mycobacterium abscessus (sensu lato) strains.

Science.gov (United States)

Macheras, Edouard; Roux, Anne-Laure; Bastian, Sylvaine; Leão, Sylvia Cardoso; Palaci, Moises; Sivadon-Tardy, Valérie; Gutierrez, Cristina; Richter, Elvira; Rüsch-Gerdes, Sabine; Pfyffer, Gaby; Bodmer, Thomas; Cambau, Emmanuelle; Gaillard, Jean-Louis; Heym, Beate

2011-02-01

Mycobacterium abscessus, Mycobacterium bolletii, and Mycobacterium massiliense (Mycobacterium abscessus sensu lato) are closely related species that currently are identified by the sequencing of the rpoB gene. However, recent studies show that rpoB sequencing alone is insufficient to discriminate between these species, and some authors have questioned their current taxonomic classification. We studied here a large collection of M. abscessus (sensu lato) strains by partial rpoB sequencing (752 bp) and multilocus sequence analysis (MLSA). The final MLSA scheme developed was based on the partial sequences of eight housekeeping genes: argH, cya, glpK, gnd, murC, pgm, pta, and purH. The strains studied included the three type strains (M. abscessus CIP 104536(T), M. massiliense CIP 108297(T), and M. bolletii CIP 108541(T)) and 120 isolates recovered between 1997 and 2007 in France, Germany, Switzerland, and Brazil. The rpoB phylogenetic tree confirmed the existence of three main clusters, each comprising the type strain of one species. However, divergence values between the M. massiliense and M. bolletii clusters all were below 3% and between the M. abscessus and M. massiliense clusters were from 2.66 to 3.59%. The tree produced using the concatenated MLSA gene sequences (4,071 bp) also showed three main clusters, each comprising the type strain of one species. The M. abscessus cluster had a bootstrap value of 100% and was mostly compact. Bootstrap values for the M. massiliense and M. bolletii branches were much lower (71 and 61%, respectively), with the M. massiliense cluster having a fuzzy aspect. Mean (range) divergence values were 2.17% (1.13 to 2.58%) between the M. abscessus and M. massiliense clusters, 2.37% (1.5 to 2.85%) between the M. abscessus and M. bolletii clusters, and 2.28% (0.86 to 2.68%) between the M. massiliense and M. bolletii clusters. Adding the rpoB sequence to the MLSA-concatenated sequence (total sequence, 4,823 bp) had little effect on the

Spectroscopic amplifier for pin diode

International Nuclear Information System (INIS)

Alonso M, M. S.; Hernandez D, V. M.; Vega C, H. R.

2014-10-01

The photodiode remains the basic choice for the photo-detection and is widely used in optical communications, medical diagnostics and field of corpuscular radiation. In detecting radiation it has been used for monitoring radon and its progeny and inexpensive spectrometric systems. The development of a spectroscopic amplifier for Pin diode is presented which has the following characteristics: canceler Pole-Zero (P/Z) with a time constant of 8 μs; constant gain of 57, suitable for the acquisition system; 4th integrator Gaussian order to waveform change of exponential input to semi-Gaussian output and finally a stage of baseline restorer which prevents Dc signal contribution to the next stage. The operational amplifier used is the TLE2074 of BiFET technology of Texas Instruments with 10 MHz bandwidth, 25 V/μs of slew rate and a noise floor of 17 nv/(Hz)1/2. The integrated circuit has 4 operational amplifiers and in is contained the total of spectroscopic amplifier that is the goal of electronic design. The results show like the exponential input signal is converted to semi-Gaussian, modifying only the amplitude according to the specifications in the design. The total system is formed by the detector, which is the Pin diode, a sensitive preamplifier to the load, the spectroscopic amplifier that is what is presented and finally a pulse height analyzer (Mca) which is where the spectrum is shown. (Author)

Dog Y chromosomal DNA sequence: identification, sequencing and SNP discovery

Directory of Open Access Journals (Sweden)

Kirkness Ewen

2006-10-01

Full Text Available Abstract Background Population genetic studies of dogs have so far mainly been based on analysis of mitochondrial DNA, describing only the history of female dogs. To get a picture of the male history, as well as a second independent marker, there is a need for studies of biallelic Y-chromosome polymorphisms. However, there are no biallelic polymorphisms reported, and only 3200 bp of non-repetitive dog Y-chromosome sequence deposited in GenBank, necessitating the identification of dog Y chromosome sequence and the search for polymorphisms therein. The genome has been only partially sequenced for one male dog, disallowing mapping of the sequence into specific chromosomes. However, by comparing the male genome sequence to the complete female dog genome sequence, candidate Y-chromosome sequence may be identified by exclusion. Results The male dog genome sequence was analysed by Blast search against the human genome to identify sequences with a best match to the human Y chromosome and to the female dog genome to identify those absent in the female genome. Candidate sequences were then tested for male specificity by PCR of five male and five female dogs. 32 sequences from the male genome, with a total length of 24 kbp, were identified as male specific, based on a match to the human Y chromosome, absence in the female dog genome and male specific PCR results. 14437 bp were then sequenced for 10 male dogs originating from Europe, Southwest Asia, Siberia, East Asia, Africa and America. Nine haplotypes were found, which were defined by 14 substitutions. The genetic distance between the haplotypes indicates that they originate from at least five wolf haplotypes. There was no obvious trend in the geographic distribution of the haplotypes. Conclusion We have identified 24159 bp of dog Y-chromosome sequence to be used for population genetic studies. We sequenced 14437 bp in a worldwide collection of dogs, identifying 14 SNPs for future SNP analyses, and

Chromate adsorption on selected soil minerals: Surface complexation modeling coupled with spectroscopic investigation

Energy Technology Data Exchange (ETDEWEB)

Veselská, Veronika, E-mail: veselskav@fzp.czu.cz [Department of Environmental Geosciences, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcka 129, CZ-16521, Prague (Czech Republic); Fajgar, Radek [Department of Analytical and Material Chemistry, Institute of Chemical Process Fundamentals of the CAS, v.v.i., Rozvojová 135/1, CZ-16502, Prague (Czech Republic); Číhalová, Sylva [Department of Environmental Geosciences, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcka 129, CZ-16521, Prague (Czech Republic); Bolanz, Ralph M. [Institute of Geosciences, Friedrich-Schiller-University Jena, Carl-Zeiss-Promenade 10, DE-07745, Jena (Germany); Göttlicher, Jörg; Steininger, Ralph [ANKA Synchrotron Radiation Facility, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, DE-76344, Eggenstein-Leopoldshafen (Germany); Siddique, Jamal A.; Komárek, Michael [Department of Environmental Geosciences, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcka 129, CZ-16521, Prague (Czech Republic)

2016-11-15

Highlights: • Study of Cr(VI) adsorption on soil minerals over a large range of conditions. • Combined surface complexation modeling and spectroscopic techniques. • Diffuse-layer and triple-layer models used to obtain fits to experimental data. • Speciation of Cr(VI) and Cr(III) was assessed. - Abstract: This study investigates the mechanisms of Cr(VI) adsorption on natural clay (illite and kaolinite) and synthetic (birnessite and ferrihydrite) minerals, including its speciation changes, and combining quantitative thermodynamically based mechanistic surface complexation models (SCMs) with spectroscopic measurements. Series of adsorption experiments have been performed at different pH values (3–10), ionic strengths (0.001–0.1 M KNO{sub 3}), sorbate concentrations (10{sup −4}, 10{sup −5}, and 10{sup −6} M Cr(VI)), and sorbate/sorbent ratios (50–500). Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy were used to determine the surface complexes, including surface reactions. Adsorption of Cr(VI) is strongly ionic strength dependent. For ferrihydrite at pH <7, a simple diffuse-layer model provides a reasonable prediction of adsorption. For birnessite, bidentate inner-sphere complexes of chromate and dichromate resulted in a better diffuse-layer model fit. For kaolinite, outer-sphere complexation prevails mainly at lower Cr(VI) loadings. Dissolution of solid phases needs to be considered for better SCMs fits. The coupled SCM and spectroscopic approach is thus useful for investigating individual minerals responsible for Cr(VI) retention in soils, and improving the handling and remediation processes.

ON THE SPECTROSCOPIC CLASSES OF NOVAE IN M33

International Nuclear Information System (INIS)

Shafter, A. W.; Darnley, M. J.; Bode, M. F.; Ciardullo, R.

2012-01-01

We report the initial results from an ongoing multi-year spectroscopic survey of novae in M33. The survey resulted in the spectroscopic classification of six novae (M33N 2006-09a, 2007-09a, 2009-01a, 2010-10a, 2010-11a, and 2011-12a) and a determination of rates of decline (t 2 times) for four of them (2006-09a, 2007-09a, 2009-01a, and 2010-10a). When these data are combined with existing spectroscopic data for two additional M33 novae (2003-09a and 2008-02a), we find that five of the eight novae with available spectroscopic class appear to be members of either the He/N or Fe IIb (hybrid) classes, with only two clear members of the Fe II spectroscopic class. This initial finding is very different from what would be expected based on the results for M31 and the Galaxy where Fe II novae dominate, and the He/N and Fe IIb classes together make up only ∼20% of the total. It is plausible that the increased fraction of He/N and Fe IIb novae observed in M33 thus far may be the result of the younger stellar population that dominates this galaxy, which is expected to produce novae that harbor generally more massive white dwarfs than those typically associated with novae in M31 or the Milky Way.

Methylene blue binding to DNA with alternating AT base sequence: minor groove binding is favored over intercalation.

Science.gov (United States)

Rohs, Remo; Sklenar, Heinz

2004-04-01

The results presented in this paper on methylene blue (MB) binding to DNA with AT alternating base sequence complement the data obtained in two former modeling studies of MB binding to GC alternating DNA. In the light of the large amount of experimental data for both systems, this theoretical study is focused on a detailed energetic analysis and comparison in order to understand their different behavior. Since experimental high-resolution structures of the complexes are not available, the analysis is based on energy minimized structural models of the complexes in different binding modes. For both sequences, four different intercalation structures and two models for MB binding in the minor and major groove have been proposed. Solvent electrostatic effects were included in the energetic analysis by using electrostatic continuum theory, and the dependence of MB binding on salt concentration was investigated by solving the non-linear Poisson-Boltzmann equation. We find that the relative stability of the different complexes is similar for the two sequences, in agreement with the interpretation of spectroscopic data. Subtle differences, however, are seen in energy decompositions and can be attributed to the change from symmetric 5'-YpR-3' intercalation to minor groove binding with increasing salt concentration, which is experimentally observed for the AT sequence at lower salt concentration than for the GC sequence. According to our results, this difference is due to the significantly lower non-electrostatic energy for the minor groove complex with AT alternating DNA, whereas the slightly lower binding energy to this sequence is caused by a higher deformation energy of DNA. The energetic data are in agreement with the conclusions derived from different spectroscopic studies and can also be structurally interpreted on the basis of the modeled complexes. The simple static modeling technique and the neglect of entropy terms and of non-electrostatic solute

Spectroscopic studies of the transplutonium elements

International Nuclear Information System (INIS)

Carnall, W.T.; Conway, J.G.

1983-01-01

The challenging opportunity to develop insights into both atomic structure and the effects of bonding in compounds makes the study of actinide spectroscopy a particularly fruitful and exciting area of scientific endeavor. It is also the interpretation of f-element spectra that has stimulated the development of the most sophisticated theoretical modeling attempted for any elements in the periodic table. The unique nature of the spectra and the wealth of fine detail revealed make possible sensitive tests of both physical models and the results of Hartree-Fock type ab initio calculations. This paper focuses on the unique character of heavy actinide spectroscopy. It discusses how it differs from that of the lighter member of the series and what are the special properties that are manifested. Following the introduction, the paper covers the following: (1) the role of systematic studies and the relationships of heavy-actinide spectroscopy to ongoing spectroscopic investigations of the lighter members of the series; (2) atomic (free-ion) spectra which covers the present status of spectroscopic studies with transplutonium elements, and future needs and directions in atomic spectroscopy; (3) the spectra of actinide compounds which covers the present status and future directions of spectroscopic studies with compounds of the transplutonium elements; and other spectroscopies. 1 figure, 2 tables

2D and 3D Models of Convective Turbulence and Oscillations in Intermediate-Mass Main-Sequence Stars

Science.gov (United States)

Guzik, Joyce Ann; Morgan, Taylor H.; Nelson, Nicholas J.; Lovekin, Catherine; Kitiashvili, Irina N.; Mansour, Nagi N.; Kosovichev, Alexander

2015-08-01

We present multidimensional modeling of convection and oscillations in main-sequence stars somewhat more massive than the sun, using three separate approaches: 1) Applying the spherical 3D MHD ASH (Anelastic Spherical Harmonics) code to simulate the core convection and radiative zone. Our goal is to determine whether core convection can excite low-frequency gravity modes, and thereby explain the presence of low frequencies for some hybrid gamma Dor/delta Sct variables for which the envelope convection zone is too shallow for the convective blocking mechanism to drive g modes; 2) Using the 3D planar ‘StellarBox’ radiation hydrodynamics code to model the envelope convection zone and part of the radiative zone. Our goals are to examine the interaction of stellar pulsations with turbulent convection in the envelope, excitation of acoustic modes, and the role of convective overshooting; 3) Applying the ROTORC 2D stellar evolution and dynamics code to calculate evolution with a variety of initial rotation rates and extents of core convective overshooting. The nonradial adiabatic pulsation frequencies of these nonspherical models will be calculated using the 2D pulsation code NRO of Clement. We will present new insights into gamma Dor and delta Sct pulsations gained by multidimensional modeling compared to 1D model expectations.

Pre-ionization and spectroscopic diagnostic of plasma generated and confined by magnetic fields

International Nuclear Information System (INIS)

Honda, R.Y.

1980-01-01

A θ-pinch system has been constructed with pre-heating devices with a total energy of 2 kJ. During this experiment a He Plasma was studied using the following three different diagnostics. a) Magnetic Probes b) Visible Spectroscopy using the Optical Multichannel Analyser - OMA c) Image Converter Camera. The experimental results have been checked with existing theoretical models. The electrical characteristics of the system were determined with the magnetic probe. The Doppler and Stark broadening effects of the λ o = 4686 (angstrom) (HeII) have been used to determine the ionic temperature and electronic density respectively. The time evolution of these parameters was obtained using the OMA. The dynamics of the plasma were observed by high speed photography. Instabilities in the plasma columm have been observed. Good agreement between the experimental and theoretical values was obtained. (author) [pt

Spectroscopic investigation of degradation of rapseed oil methyl esters

International Nuclear Information System (INIS)

Kampars, V.

2003-01-01

Investigation of rapseed oil methyl esters by US VIS and FTIR spectroscopy during the heating at 80 deg C were carried out. The degradation begins immediately after beginning of experiment. The main process at first stage is destroying of carotenoids and oxidation of polyunsaturated fatty acids by forming conjugated polyenes. Between the formation of conjugated triens and destroying of carotenoids exist definite interconnection, but there isn't evidence for the protective activity of carotenoids. As follows from FTIR spectroscopy the increase of carbonyl compounds concentration begins immediately after the start of experiment and continues all the time. Despite to the complex character the peak at 220 nm is only one spectroscopic characteristic with a sharp alteration point and may be used for the fast and simple detection of storage stability of bio diesels. (authors)

Regularized Pre-image Estimation for Kernel PCA De-noising

DEFF Research Database (Denmark)

Abrahamsen, Trine Julie; Hansen, Lars Kai

2011-01-01

The main challenge in de-noising by kernel Principal Component Analysis (PCA) is the mapping of de-noised feature space points back into input space, also referred to as “the pre-image problem”. Since the feature space mapping is typically not bijective, pre-image estimation is inherently illposed...

Sparse spectral deconvolution algorithm for noncartesian MR spectroscopic imaging.

Science.gov (United States)

Bhave, Sampada; Eslami, Ramin; Jacob, Mathews

2014-02-01

To minimize line shape distortions and spectral leakage artifacts in MR spectroscopic imaging (MRSI). A spatially and spectrally regularized non-Cartesian MRSI algorithm that uses the line shape distortion priors, estimated from water reference data, to deconvolve the spectra is introduced. Sparse spectral regularization is used to minimize noise amplification associated with deconvolution. A spiral MRSI sequence that heavily oversamples the central k-space regions is used to acquire the MRSI data. The spatial regularization term uses the spatial supports of brain and extracranial fat regions to recover the metabolite spectra and nuisance signals at two different resolutions. Specifically, the nuisance signals are recovered at the maximum resolution to minimize spectral leakage, while the point spread functions of metabolites are controlled to obtain acceptable signal-to-noise ratio. The comparisons of the algorithm against Tikhonov regularized reconstructions demonstrates considerably reduced line-shape distortions and improved metabolite maps. The proposed sparsity constrained spectral deconvolution scheme is effective in minimizing the line-shape distortions. The dual resolution reconstruction scheme is capable of minimizing spectral leakage artifacts. Copyright © 2013 Wiley Periodicals, Inc.

Nuclear resonance vibrational spectroscopic studies of iron-containing biomolecules

International Nuclear Information System (INIS)

Ohta, Takehiro; Seto, Makoto

2014-01-01

In this review, we report recent nuclear resonance vibrational spectroscopic (NRVS) studies of iron-containing biomolecules and their model complexes. The NRVS is synchrotron-based element-specific vibrational spectroscopic methods. Unlike Raman and infrared spectroscopy, the NRVS can investigate all iron motions without selection rules, which provide atomic level insights into the structure/reactivity correlation of biologically relevant iron complexes. (author)

Probing superconductors. Spectroscopic-imaging scanning tunneling microscopy

International Nuclear Information System (INIS)

Hanaguri, Tetsuo

2011-01-01

Discovery of high-temperature superconductivity in a cuprate triggered developments of various spectroscopic tools which have been utilized to elucidate electronic states of this mysterious compound. Particularly, angle-resolved photoemission spectroscopy and scanning-tunneling microscopy/spectroscopy are improved considerably. It is now possible to map the superconducting gap in both momentum and real spaces using these two techniques. Here we review spectroscopic-imaging scanning tunneling microscopy which is able to explore momentum-space phase structure of the superconducting gap, as well as real-space structure. Applications of this technique to a cuprate and an iron-based superconductor are discussed. (author)

A search for photometric and spectroscopic evolutionary changes in the young planetary nebula Vy 2-2

Science.gov (United States)

Arkhipova, V. P.; Burlak, M. A.; Esipov, V. F.; Ikonnikova, N. P.; Komissarova, G. V.

2017-12-01

The results of long-term photometric and spectroscopic observations of the young compact planetary nebula Vy 2-2 (PNG 045.4-02.7) are presented. The UBV photometry in 1990-2016 has revealed a slight brightness trend in the yearly averaged data, most pronounced in the V band. We have measured the relative fluxes of optical emission lines on the spectrograms taken with the 1.25-m telescope at the Southern Station of the SAI MSU in 1999-2016, estimated the absolute flux in the Hβ line to be F(H β) = (2.1 ± 0.4) × 10-12 erg cm-2 s-1, and determined the interstellar extinction constant c(Hβ) = 1.8. The electron temperature and density in the nebula have been estimated from diagnostic line ratios: Te = (10-12) × 103 K and Ne ≥ 105 cm-3. To detect any possible evolutionary changes, we have compared the new observations with the archival data obtained over the entire history of spectroscopic observations of Vy 2-2. No significant changes in the relative intensities of the strongest emission lines and the integrated flux in the H β line exceeding the observational errors have been found. We have revealed a tendency for the intensity ratio F(λ4363)/F(λ4959) to decrease with time, which may be related to a decrease in the electron density in the nebula. Based on our photometric and spectroscopic data, we have estimated the luminosity of the central star of Vy 2-2, which corresponds to the evolutionary tracks for the most massive post-AGB stars of the O-rich sequence.

On the use of the spectroscopic techniques to model the interactions between radionuclides and solid minerals

Energy Technology Data Exchange (ETDEWEB)

Simoni, E. [IPN, Paris XI University, 91406 Orsay (France)]. e-mail: simoni@ipno.in2p3.fr

2004-07-01

In order to determine the radionuclides sorption constants on solid natural minerals, both thermodynamic and structural investigations, using spectroscopic techniques, are presented. The natural clays, that could be used as engineering barrier in the nuclear waste geological repository, are rather complex minerals. Therefore, in order to understand how these natural materials retain the radionuclides, it is necessary first to perform these studies on simple substrates such as phosphates, oxides and silicates (as powder and single crystal as well) and then extrapolate the obtained results on the natural minerals. As examples, the main results on the sorption processes of the hexavalent uranium onto zircon (ZrSiO{sub 4}) and lanthanum phosphate (LaPO{sub 4}) are presented. The corresponding sorption curves are simulated using the results obtained with the following spectroscopic techniques: laser induced spectro fluorimetry, X-ray photoelectron spectroscopy (XP S), X-ray absorption spectroscopy (Exafs). Finally, the thermodynamic sorption constants are calculated. (Author)

Generalized locally Toeplitz sequences theory and applications

CERN Document Server

Garoni, Carlo

2017-01-01

Based on their research experience, the authors propose a reference textbook in two volumes on the theory of generalized locally Toeplitz sequences and their applications. This first volume focuses on the univariate version of the theory and the related applications in the unidimensional setting, while the second volume, which addresses the multivariate case, is mainly devoted to concrete PDE applications. This book systematically develops the theory of generalized locally Toeplitz (GLT) sequences and presents some of its main applications, with a particular focus on the numerical discretization of differential equations (DEs). It is the first book to address the relatively new field of GLT sequences, which occur in numerous scientific applications and are especially dominant in the context of DE discretizations. Written for applied mathematicians, engineers, physicists, and scientists who (perhaps unknowingly) encounter GLT sequences in their research, it is also of interest to those working in the fields of...

Improvement of the galvanized coating quality of high strength dual phase steels by pre-electroplating nickel layer

Energy Technology Data Exchange (ETDEWEB)

Zhong, N. [Institute of Marine Materials Science and Engineering, Shanghai Maritime University, Shanghai 200135 (China); Zhang, K. [Institute of Concrete Pumps Machinery R and D, Sany Heavy Industry Co., Ltd. 410100 (China); Li, J. [Baoshan Iron and Steel Co., Ltd, Shanghai 201900 (China); Hu, W.B. [State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240 (China)

2011-03-15

Galvanized dual phase steel sheets are used extensively in the industrial applications because of their excellent mechanical properties and superior corrosion resistance, but the segregation of alloying elements and the formation of oxides on the steel surface often have a deleterious effect on coating adhesion during the galvanizing process. In order to improve the coating quality, a nickel layer was pre-electroplated on the steel substrate before galvanizing and it's found that there is an improvement in the coating quality. The coating microstructures were investigated by scanning electron microscopy together with energy dispersive X-ray spectroscope, glow discharge optical emission spectroscope and X-ray diffractions. The experimental results show that the compact Ni{sub 3}Zn{sub 22} intermetallic layer formed at the zinc/nickel interface during the galvanizing process, prohibiting the nucleation and the growth of the {zeta}-Zn phase layer and resulting in the improvement of the zinc coating adhesion. (Copyright copyright 2011 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

THE TIME-DOMAIN SPECTROSCOPIC SURVEY: UNDERSTANDING THE OPTICALLY VARIABLE SKY WITH SEQUELS IN SDSS-III

Energy Technology Data Exchange (ETDEWEB)

Ruan, John J.; Anderson, Scott F.; Davenport, James R. A. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Green, Paul J.; Morganson, Eric [Harvard Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Eracleous, Michael; Brandt, William N. [Department of Astronomy and Astrophysics, 525 Davey Lab, The Pennsylvania State University, University Park, PA 16802 (United States); Myers, Adam D. [Department of Physics and Astronomy 3905, University of Wyoming, 1000 E. University, Laramie, WY 82071 (United States); Badenes, Carles [Department of Physics and Astronomy and Pittsburgh Particle Physics, Astrophysics, and Cosmology Center (PITT-PACC), University of Pittsburgh (United States); Bershady, Matthew A. [Department of Astronomy, University of Wisconsin-Madison, 475 N. Charter Street, Madison, WI 53706 (United States); Chambers, Kenneth C.; Flewelling, Heather; Kaiser, Nick [Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States); Dawson, Kyle S. [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Heckman, Timothy M. [Center for Astrophysical Sciences, Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Isler, Jedidah C. [Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States); Kneib, Jean-Paul [Laboratoire d’astrophysique, Ecole Polytechnique Fédérale de Lausanne Observatoire de Sauverny, 1290 Versoix (Switzerland); MacLeod, Chelsea L.; Ross, Nicholas P. [Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh, EH9 3HJ (United Kingdom); Paris, Isabelle, E-mail: jruan@astro.washington.edu [INAF—Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, I-34131 Trieste (Italy); and others

2016-07-10

The Time-Domain Spectroscopic Survey (TDSS) is an SDSS-IV eBOSS subproject primarily aimed at obtaining identification spectra of ∼220,000 optically variable objects systematically selected from SDSS/Pan-STARRS1 multi-epoch imaging. We present a preview of the science enabled by TDSS, based on TDSS spectra taken over ∼320 deg{sup 2} of sky as part of the SEQUELS survey in SDSS-III, which is in part a pilot survey for eBOSS in SDSS-IV. Using the 15,746 TDSS-selected single-epoch spectra of photometrically variable objects in SEQUELS, we determine the demographics of our variability-selected sample and investigate the unique spectral characteristics inherent in samples selected by variability. We show that variability-based selection of quasars complements color-based selection by selecting additional redder quasars and mitigates redshift biases to produce a smooth quasar redshift distribution over a wide range of redshifts. The resulting quasar sample contains systematically higher fractions of blazars and broad absorption line quasars than from color-selected samples. Similarly, we show that M dwarfs in the TDSS-selected stellar sample have systematically higher chromospheric active fractions than the underlying M-dwarf population based on their H α emission. TDSS also contains a large number of RR Lyrae and eclipsing binary stars with main-sequence colors, including a few composite-spectrum binaries. Finally, our visual inspection of TDSS spectra uncovers a significant number of peculiar spectra, and we highlight a few cases of these interesting objects. With a factor of ∼15 more spectra, the main TDSS survey in SDSS-IV will leverage the lessons learned from these early results for a variety of time-domain science applications.

The Bergshamra earthquake sequence of December 23, 1979

International Nuclear Information System (INIS)

Kulhanek, O.; John, N.; Meyer, K.; Eck, T. van; Wahlstroem, R.

1980-08-01

On December 23, 1979 an earthquake sequence occurred near Bergshamra-Roslagen, Sweden, about 50 km northeast of Stockholm. The main shock, which has been assigned a magnitude Msub(L)=3.2, has been followed, with a 3 minute delay, by a shock of magnitude Msub(L)=2.6 and, with additional 21-minute delay, by a third shock of magnitude Msub(L)=2.0. Whereas the main shock was recorded by almost all Finnish, Norwegian and Swedish permanent stations, the whole sequence has been observed only at UPP (Δ=68 km). A six-week field survey in the epicentral area revealed a number of small aftershocks located close to the main shock. The Bergshamra sequence took place in a zone of very low seismicity in eastern central Sweden and for Swedish earthquakes at unusual shallow depth. Since the epicentre lies less than 100 km from a nuclear power plant in Forsmark, the sequence received publicity which was not in proportion to the size of the shock. At his occasion, some rather strange explanations of the shock emerged. (Auth.)

The trochlear pre-ossification center: a normal developmental stage and potential pitfall on MR images

Energy Technology Data Exchange (ETDEWEB)

Jaimes, Camilo [The Children' s Hospital of Philadelphia, Department of Radiology, Philadelphia, PA (United States); Jimenez, Mauricio [Hospital of the University of Pennsylvania, Department of Radiology, Philadelphia, PA (United States); Marin, Diana [Miami Children' s Hospital, Department of Radiology, Miami, FL (United States); Ho-Fung, Victor; Jaramillo, Diego [The Children' s Hospital of Philadelphia, Department of Radiology, Philadelphia, PA (United States); University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA (United States)

2012-11-15

The hypertrophic changes that occur in the cartilage of an epiphysis prior to the onset of ossification are known as the pre-ossification center. Awareness of the appearance of the pre-ossification center on MR images is important to avoid confusing normal developmental changes with pathology. The purpose of this study was to determine the characteristics of the trochlear pre-ossification center on MR imaging and examine age and gender differences. We retrospectively analyzed MR images from 61 children. The trochleas were categorized into three types on the basis of signal intensity (SI). Trochlear types were compared to age and gender. There was no significant difference between the ages of boys and girls. Type 1 trochleas showed homogeneous SI on all pulse sequences. Type 2 trochleas demonstrated a focus of high SI in the epiphyseal cartilage on fat-suppressed water-sensitive sequences, with high or intermediate SI on gradient-echo images (pre-ossification center). Type 3 trochleas showed low SI on fat-suppressed water-sensitive sequences and gradient-echo images. Thirty-seven trochleas were described as type 1, sixteen as type 2 and eight as type 3. ANOVAs confirmed a statistically significant difference in the age of children with type 3 trochleas and those with types 1 and 2 (P < 0.001). Spearman rank correlations determined a positive relationship between trochlear type and age of the children (r = 0.53). Development-related changes in the trochlea follow a predictable pattern. The signal characteristics of the pre-ossification center likely reflect normal chondrocyte hypertrophy and an increase in free water in the matrix. (orig.)

Developmental ossification sequences of the appendicular and axial ...

African Journals Online (AJOL)

A pre-hatch developmental study on ossification sequences of axial and appendicular skeletal system in Kuttanad duck embryos was undertaken using 78 viable embryos. From day 3 to day 7 of incubation no ossification densities were seen both by alizarin red staining and computerized radiography. The first indication of ...

A YOUNG ECLIPSING BINARY AND ITS LUMINOUS NEIGHBORS IN THE EMBEDDED STAR CLUSTER Sh 2-252E

Energy Technology Data Exchange (ETDEWEB)

Lester, Kathryn V.; Gies, Douglas R.; Guo, Zhao, E-mail: lester@chara.gsu.edu, E-mail: gies@chara.gsu.edu, E-mail: guo@chara.gsu.edu [Center for High Angular Resolution Astronomy and Department of Physics and Astronomy, Georgia State University, P.O. Box 5060, Atlanta, GA 30302-5060 (United States)

2016-12-01

We present a photometric and light curve analysis of an eccentric eclipsing binary in the K2 Campaign 0 field, which resides in Sh 2-252E, a young star cluster embedded in an H ii region. We describe a spectroscopic investigation of the three brightest stars in the crowded aperture to identify which is the binary system. We find that none of these stars are components of the eclipsing binary system, which must be one of the fainter nearby stars. These bright cluster members all have remarkable spectra: Sh 2-252a (EPIC 202062176) is a B0.5 V star with razor sharp absorption lines, Sh 2-252b is a Herbig A0 star with disk-like emission lines, and Sh 2-252c is a pre-main-sequence star with very red color.

Passive Spectroscopic Diagnostics for Magnetically-confined Fusion Plasmas

International Nuclear Information System (INIS)

Stratton, B.C.; Bitter, M.; Hill, K.W.; Hillis, D.L.; Hogan, J.T.

2007-01-01

Spectroscopy of radiation emitted by impurities and hydrogen isotopes plays an important role in the study of magnetically-confined fusion plasmas, both in determining the effects of impurities on plasma behavior and in measurements of plasma parameters such as electron and ion temperatures and densities, particle transport, and particle influx rates. This paper reviews spectroscopic diagnostics of plasma radiation that are excited by collisional processes in the plasma, which are termed 'passive' spectroscopic diagnostics to distinguish them from 'active' spectroscopic diagnostics involving injected particle and laser beams. A brief overview of the ionization balance in hot plasmas and the relevant line and continuum radiation excitation mechanisms is given. Instrumentation in the soft X-ray, vacuum ultraviolet, ultraviolet, visible, and near-infrared regions of the spectrum is described and examples of measurements are given. Paths for further development of these measurements and issues for their implementation in a burning plasma environment are discussed.

Passive Spectroscopic Diagnostics for Magnetically-confined Fusion Plasmas

Energy Technology Data Exchange (ETDEWEB)

Stratton, B. C.; Biter, M.; Hill, K. W.; Hillis, D. L.; Hogan, J. T.

2007-07-18

Spectroscopy of radiation emitted by impurities and hydrogen isotopes plays an important role in the study of magnetically-confined fusion plasmas, both in determining the effects of impurities on plasma behavior and in measurements of plasma parameters such as electron and ion temperatures and densities, particle transport, and particle influx rates. This paper reviews spectroscopic diagnostics of plasma radiation that are excited by collisional processes in the plasma, which are termed 'passive' spectroscopic diagnostics to distinguish them from 'active' spectroscopic diagnostics involving injected particle and laser beams. A brief overview of the ionization balance in hot plasmas and the relevant line and continuum radiation excitation mechanisms is given. Instrumentation in the soft X-ray, vacuum ultraviolet, ultraviolet, visible, and near-infrared regions of the spectrum is described and examples of measurements are given. Paths for further development of these measurements and issues for their implementation in a burning plasma environment are discussed.

THE BARYON OSCILLATION SPECTROSCOPIC SURVEY OF SDSS-III

International Nuclear Information System (INIS)

Dawson, Kyle S.; Ahn, Christopher P.; Bolton, Adam S.; Schlegel, David J.; Bailey, Stephen; Anderson, Scott F.; Bhardwaj, Vaishali; Aubourg, Éric; Bautista, Julian E.; Barkhouser, Robert H.; Beifiori, Alessandra; Berlind, Andreas A.; Bizyaev, Dmitry; Brewington, Howard; Blake, Cullen H.; Blanton, Michael R.; Blomqvist, Michael; Borde, Arnaud; Bovy, Jo; Brandt, W. N.

2013-01-01

The Baryon Oscillation Spectroscopic Survey (BOSS) is designed to measure the scale of baryon acoustic oscillations (BAO) in the clustering of matter over a larger volume than the combined efforts of all previous spectroscopic surveys of large-scale structure. BOSS uses 1.5 million luminous galaxies as faint as i = 19.9 over 10,000 deg 2 to measure BAO to redshifts z A to an accuracy of 1.0% at redshifts z = 0.3 and z = 0.57 and measurements of H(z) to 1.8% and 1.7% at the same redshifts. Forecasts for Lyα forest constraints predict a measurement of an overall dilation factor that scales the highly degenerate D A (z) and H –1 (z) parameters to an accuracy of 1.9% at z ∼ 2.5 when the survey is complete. Here, we provide an overview of the selection of spectroscopic targets, planning of observations, and analysis of data and data quality of BOSS.

Enzymatic and spectroscopic properties of a thermostable [NiFe]‑hydrogenase performing H2-driven NAD+-reduction in the presence of O2.

Science.gov (United States)

Preissler, Janina; Wahlefeld, Stefan; Lorent, Christian; Teutloff, Christian; Horch, Marius; Lauterbach, Lars; Cramer, Stephen P; Zebger, Ingo; Lenz, Oliver

2018-01-01

Biocatalysts that mediate the H 2 -dependent reduction of NAD + to NADH are attractive from both a fundamental and applied perspective. Here we present the first biochemical and spectroscopic characterization of an NAD + -reducing [NiFe]‑hydrogenase that sustains catalytic activity at high temperatures and in the presence of O 2 , which usually acts as an inhibitor. We isolated and sequenced the four structural genes, hoxFUYH, encoding the soluble NAD + -reducing [NiFe]‑hydrogenase (SH) from the thermophilic betaproteobacterium, Hydrogenophilus thermoluteolus TH-1 T (Ht). The HtSH was recombinantly overproduced in a hydrogenase-free mutant of the well-studied, H 2 -oxidizing betaproteobacterium Ralstonia eutropha H16 (Re). The enzyme was purified and characterized with various biochemical and spectroscopic techniques. Highest H 2 -mediated NAD + reduction activity was observed at 80°C and pH6.5, and catalytic activity was found to be sustained at low O 2 concentrations. Infrared spectroscopic analyses revealed a spectral pattern for as-isolated HtSH that is remarkably different from those of the closely related ReSH and other [NiFe]‑hydrogenases. This indicates an unusual configuration of the oxidized catalytic center in HtSH. Complementary electron paramagnetic resonance spectroscopic analyses revealed spectral signatures similar to related NAD + -reducing [NiFe]‑hydrogenases. This study lays the groundwork for structural and functional analyses of the HtSH as well as application of this enzyme for H 2 -driven cofactor recycling under oxic conditions at elevated temperatures. Copyright © 2017 Elsevier B.V. All rights reserved.

On pre-test sensitisation and peer assessment to enhance learning gain in science education

NARCIS (Netherlands)

Bos, Floor/Floris

2009-01-01

*The main part of this thesis focuses on designing, optimising, and studying the embedding of two types of interventions: pre-testing and peer assessment, both supported by or combined with ICT-tools. * Pre-test sensitisation is used intentionally to boost the learning gain of the main intervention,

galaxie--CGI scripts for sequence identification through automated phylogenetic analysis.

Science.gov (United States)

Nilsson, R Henrik; Larsson, Karl-Henrik; Ursing, Björn M

2004-06-12

The prevalent use of similarity searches like BLAST to identify sequences and species implicitly assumes the reference database to be of extensive sequence sampling. This is often not the case, restraining the correctness of the outcome as a basis for sequence identification. Phylogenetic inference outperforms similarity searches in retrieving correct phylogenies and consequently sequence identities, and a project was initiated to design a freely available script package for sequence identification through automated Web-based phylogenetic analysis. Three CGI scripts were designed to facilitate qualified sequence identification from a Web interface. Query sequences are aligned to pre-made alignments or to alignments made by ClustalW with entries retrieved from a BLAST search. The subsequent phylogenetic analysis is based on the PHYLIP package for inferring neighbor-joining and parsimony trees. The scripts are highly configurable. A service installation and a version for local use are found at http://andromeda.botany.gu.se/galaxiewelcome.html and http://galaxie.cgb.ki.se

Variable extinction in HD 45677 and the evolution of dust grains in pre-main-sequence disks

Science.gov (United States)

Sitko, Michael L.; Halbedel, Elaine M.; Lawrence, Geoffrey F.; Smith, J. Allyn; Yanow, Ken

1994-01-01

Changes in the UV extinction and IR emission were sought in the Herbig Ae/Be star candidate HD 45677 (= FS CMa) by comparing UV, optical, and IR observations made approximately 10 yr apart. HD 45677 varied significantly, becoming more than 50% brighter in the UV and optical than it was a decade ago. A comparison of the observations between epochs indicates that if the variations are due to changes in dust obscuration, the dust acts as a gray absorber into the near-IR and must be depleted in grains smaller than 1 micron. This is similar to the results obtained on the circumstellar disks of stars like Vega and Beta Pic, and suggests that radiation pressure may be responsible for the small-grain depletion. In addition, the total IR flux seems to have declined, indicating a decrease in the total mass of the dust envelope that contributes to the IR emission in this part of the spectrum. Due to the anomalous nature of the extinction, the use of normal extinction curves to deredden the spectral energy distributions of stars with circumstellar dust may lead to significant errors and should be used with great caution.

Proton MR spectroscopic imaging of basal ganglia and thalamus in neurofibromatosis type 1: correlation with T2 hyperintensities

International Nuclear Information System (INIS)

Barbier, Charlotte; Barantin, Laurent; Chabernaud, Camille; Bertrand, Philippe; Sembely, Catherine; Sirinelli, Dominique; Castelnau, Pierre; Cottier, Jean-Philippe

2011-01-01

Neurofibromatosis type 1 (NF1) is frequently associated with hyperintense lesions on T2-weighted images called ''unidentified bright objects'' (UBO). To better characterize the functional significance of UBO, we investigate the basal ganglia and thalamus using spectroscopic imaging in children with NF1 and compare the results to anomalies observed on T2-weighted images. Magnetic resonance (MR) data of 25 children with NF1 were analyzed. On the basis of T2-weighted images analysis, two groups were identified: one with normal MR imaging (UBO- group; n = 10) and one with UBO (UBO+ group; n = 15). Within the UBO+ group, a subpopulation of patients (n = 5) only had lesions of the basal ganglia. We analyzed herein seven regions of interest (ROIs) for each side: caudate nucleus, capsulo-lenticular region, lateral and posterior thalamus, thalamus (lateral and posterior voxels combined), putamen, and striatum. For each ROI, a spectrum of the metabolites and their ratio was obtained. Patients with abnormalities on T2-weighted images had significantly lower NAA/Cr, NAA/Cho, and NAA/mI ratios in the lateral right thalamus compared with patients with normal T2. These abnormal spectroscopic findings were not observed in capsulo-lenticular regions that had UBO but in the thalamus region that was devoid of UBO. Multivoxel spectroscopic imaging using short-time echo showed spectroscopic abnormalities in the right thalamus of NF1 patients harboring UBO, which were mainly located in the basal ganglia. This finding could reflect the anatomical and functional interactions of these regions. (orig.)

Quantification of UV-Visible and Laser Spectroscopic Techniques for Materials Accountability and Process Control

International Nuclear Information System (INIS)

Czerwinski, Kenneth; Weck, Phil

2013-01-01

-Visible spectroscopy studies. The use of TRLFS to examine Cm and U will provide data to evaluate lifetime, peak location, and peak ratios (mainly for U). The bases for the spectroscopic techniques have been investigated, providing fundamental evidence for the application's utility.

IMPROVING THE SKILL AND THE INTEREST OF WRITING ADVERTISEMENTS AND POSTERS THROUGH ESA SEQUENCE

Directory of Open Access Journals (Sweden)

author Fatma Yuniarti

2015-01-01

Full Text Available The action reserach aims at improving the students’ writing skill especially to write advertsements and posters. Both are the short functional texts to be learned at the second semester. According to the data on pre cycle, the students of second semester got difficulties to write advertisements and posters. A treatment was necessary to help the students overcome their problem. To consider the related literature, the writer decided to implement ESA sequence (Harmer 2001 in the class. The elements of teaching in ESA Sequence are Engage (to arouse the students’ interests, Study (learn the language focus, and Activate (use the language freely and communicatively. The data were taken from the test of the linguistic competence mastery, the students writing, and the questionnaire. The students’ linguistic competence got increased as shown by the score (58 in pre-cycle, 66 in cycle 1, and 70 in cycle 2. The students’ ability to write the short functional texts also get improved as indicated by the average score on writing tasks (53 in pre-cycle, 63 in cycle 1, 72 in cycle 2. The interest also gets better as shown by the score of the questionnaire (22,3 in pre-cycle, 33,5 in cycle 1, and 37 in cycle 2. It means ESA Sequence can improve the studets’ ability to write advertisements and posters.Key words : advertisement, ESA (Engange Study Activate, poster

Total RNA Sequencing Analysis of DCIS Progressing to Invasive Breast Cancer

Science.gov (United States)

2017-09-01

AWARD NUMBER: W81XWH-14-1-0080 TITLE: Total RNA Sequencing Analysis of DCIS Progressing to Invasive Breast Cancer . PRINCIPAL INVESTIGATOR...TITLE AND SUBTITLE Total RNA Sequencing Analysis of DCIS Progressing to Invasive Breast Cancer . 5a. CONTRACT NUMBER 5b. GRANT NUMBER GRANT11489...institutional, NIH-funded study of genetic and epigenetic alterations of pre-invasive DCIS that did or did not progress to invasive breast cancer , with an

Development of a THz spectroscopic imaging system

International Nuclear Information System (INIS)

Usami, M; Iwamoto, T; Fukasawa, R; Tani, M; Watanabe, M; Sakai, K

2002-01-01

We have developed a real-time THz imaging system based on the two-dimensional (2D) electro-optic (EO) sampling technique. Employing the 2D EO-sampling technique, we can obtain THz images using a CCD camera at a video rate of up to 30 frames per second. A spatial resolution of 1.4 mm was achieved. This resolution was reasonably close to the theoretical limit determined by diffraction. We observed not only static objects but also moving ones. To acquire spectroscopic information, time-domain images were collected. By processing these images on a computer, we can obtain spectroscopic images. Spectroscopy for silicon wafers was demonstrated

Event-related potentials elicited by pre-attentive emotional changes in temporal context.

Directory of Open Access Journals (Sweden)

Tomomi Fujimura

Full Text Available The ability to detect emotional change in the environment is essential for adaptive behavior. The current study investigated whether event-related potentials (ERPs can reflect emotional change in a visual sequence. To assess pre-attentive processing, we examined visual mismatch negativity (vMMN: the negative potentials elicited by a deviant (infrequent stimulus embedded in a sequence of standard (frequent stimuli. Participants in two experiments pre-attentively viewed visual sequences of Japanese kanji with different emotional connotations while ERPs were recorded. The visual sequence in Experiment 1 consisted of neutral standards and two types of emotional deviants with a strong and weak intensity. Although the results indicated that strongly emotional deviants elicited more occipital negativity than neutral standards, it was unclear whether these negativities were derived from emotional deviation in the sequence or from the emotional significance of the deviants themselves. In Experiment 2, the two identical emotional deviants were presented against different emotional standards. One type of deviants was emotionally incongruent with the standard and the other type of deviants was emotionally congruent with the standard. The results indicated that occipital negativities elicited by deviants resulted from perceptual changes in a visual sequence at a latency of 100-200 ms and from emotional changes at latencies of 200-260 ms. Contrary to the results of the ERP experiment, reaction times to deviants showed no effect of emotional context; negative stimuli were consistently detected more rapidly than were positive stimuli. Taken together, the results suggest that brain signals can reflect emotional change in a temporal context.

Spectroscopic data

CERN Document Server

Melzer, J

1976-01-01

During the preparation of this compilation, many people contributed; the compilers wish to thank all of them. In particular they appreciate the efforts of V. Gilbertson, the manuscript typist, and those of K. C. Bregand, J. A. Kiley, and W. H. McPherson, who gave editorial assistance. They would like to thank Dr. J. R. Schwartz for his cooperation and encouragement. In addition, they extend their grati­ tude to Dr. L. Wilson of the Air Force Weapons Laboratory, who gave the initial impetus to this project. v Contents I. I ntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 . . . . . . . . . . . . . . . . 11. Organization ofthe Spectroscopic Table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Methods of Production and Experimental Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Band Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2...

Three-dimensional magnetic resonance spectroscopic imaging in the substantia nigra of healthy controls and patients with Parkinson's disease

International Nuclear Information System (INIS)

Groeger, Adriane; Godau, Jana; Berg, Daniela; Chadzynski, Grzegorz; Klose, Uwe

2011-01-01

To investigate the substantia nigra in patients with Parkinson's disease three-dimensional magnetic resonance spectroscopic imaging with high spatial resolution at 3 Tesla was performed. Regional variations of spectroscopic data between the rostral and caudal regions of the substantia nigra as well as the midbrain tegmentum areas were evaluated in healthy controls and patients with Parkinson's disease. Nine patients with Parkinson's disease and eight age- and gender-matched healthy controls were included in this study. Data were acquired by using three-dimensional magnetic resonance spectroscopic imaging measurements. The ratios between rostral and caudal voxels of the substantia nigra as well as the midbrain tegmentum areas were calculated for the main-metabolites N-acetyl aspartate, creatine, choline, and myo-inositol. Additionally, the metabolite/creatine ratios were calculated. In all subjects spectra of acceptable quality could be obtained with a nominal voxel size of 0.252 ml. The calculated rostral-to-caudal ratios of the metabolites as well as of the metabolite/creatine ratios showed with exception of choline/creatine ratio significant differences between healthy controls and patients with Parkinson's disease. The findings from this study indicate that regional variations in N-acetyl aspartate/creatine ratios in the regions of the substantia nigra may differentiate patients with Parkinson's disease and healthy controls. (orig.)

Spectroscopic Study of NGC 281 West

Science.gov (United States)

Hasan, Priya

2018-04-01

NGC 281 is a complex region of star formation at 2.8 kpc. This complex is situated 300 pc above the Galactic plane, and appears to be part of a 270 pc diameter ring of atomic and molecular clouds expanding at 22 km/s (Megeath et al. 2003). It appears that two modes of triggered star formation are at work here: an initial supernova to trigger the ring complex and the initial O stars and the subsequent triggering of low mass star formation by photoevaporation driven molecular core compression. To get a complete census of the young stellar population, we use observations from Chandra ACIS 100 ksec coupled with data from 2MASS and Spitzer. The Master X-ray catalog has 446 sources detected in different bandpasses. We present the spatial distribution of Class I, II and III sources to study the progress of star formation. We also determine the gas to dust ratio NH/AK to be 1.93 ± 0.47 ×1022 cm‑2 mag‑1 for this region. In this article, we present NGC 281 as a good target to study with the 3.6-m Devasthal Optical Telescope (DOT) in spectroscopy. With these spectra, we look for evidence for the pre-main-sequence (PMS) nature of the objects, study the properties of the detected emission lines as a function of evolutionary class, and obtain spectral types for the observed young stellar objects (YSOs). The temperatures implied by the spectral types can be combined with luminosities determined from the near-infrared (NIR) photometry to construct Hertzsprung–Russell (HR) diagrams for the clusters. By comparing the positions of the YSOs in the HR diagrams with the PMS tracks, we can determine the ages of the embedded sources and study the relative ages of the YSOs with and without optically thick circumstellar disks.

Multicenter validation of cancer gene panel-based next-generation sequencing for translational research and molecular diagnostics.

Science.gov (United States)

Hirsch, B; Endris, V; Lassmann, S; Weichert, W; Pfarr, N; Schirmacher, P; Kovaleva, V; Werner, M; Bonzheim, I; Fend, F; Sperveslage, J; Kaulich, K; Zacher, A; Reifenberger, G; Köhrer, K; Stepanow, S; Lerke, S; Mayr, T; Aust, D E; Baretton, G; Weidner, S; Jung, A; Kirchner, T; Hansmann, M L; Burbat, L; von der Wall, E; Dietel, M; Hummel, M

2018-04-01

The simultaneous detection of multiple somatic mutations in the context of molecular diagnostics of cancer is frequently performed by means of amplicon-based targeted next-generation sequencing (NGS). However, only few studies are available comparing multicenter testing of different NGS platforms and gene panels. Therefore, seven partner sites of the German Cancer Consortium (DKTK) performed a multicenter interlaboratory trial for targeted NGS using the same formalin-fixed, paraffin-embedded (FFPE) specimen of molecularly pre-characterized tumors (n = 15; each n = 5 cases of Breast, Lung, and Colon carcinoma) and a colorectal cancer cell line DNA dilution series. Detailed information regarding pre-characterized mutations was not disclosed to the partners. Commercially available and custom-designed cancer gene panels were used for library preparation and subsequent sequencing on several devices of two NGS different platforms. For every case, centrally extracted DNA and FFPE tissue sections for local processing were delivered to each partner site to be sequenced with the commercial gene panel and local bioinformatics. For cancer-specific panel-based sequencing, only centrally extracted DNA was analyzed at seven sequencing sites. Subsequently, local data were compiled and bioinformatics was performed centrally. We were able to demonstrate that all pre-characterized mutations were re-identified correctly, irrespective of NGS platform or gene panel used. However, locally processed FFPE tissue sections disclosed that the DNA extraction method can affect the detection of mutations with a trend in favor of magnetic bead-based DNA extraction methods. In conclusion, targeted NGS is a very robust method for simultaneous detection of various mutations in FFPE tissue specimens if certain pre-analytical conditions are carefully considered.

Automatic sequencing and control of Space Station airlock operations

Science.gov (United States)

Himel, Victor; Abeles, Fred J.; Auman, James; Tqi, Terry O.

1989-01-01

Procedures that have been developed as part of the NASA JSC-sponsored pre-prototype Checkout, Servicing and Maintenance (COSM) program for pre- and post-EVA airlock operations are described. This paper addresses the accompanying pressure changes in the airlock and in the Advanced Extravehicular Mobility Unit (EMU). Additionally, the paper focuses on the components that are checked out, and includes the step-by-step sequences to be followed by the crew, the required screen displays and prompts that accompany each step, and a description of the automated processes that occur.

Spectroscopic Chemical Analysis Methods and Apparatus

Science.gov (United States)

Hug, William F. (Inventor); Reid, Ray D. (Inventor); Bhartia, Rohit (Inventor); Lane, Arthur L. (Inventor)

2018-01-01

Spectroscopic chemical analysis methods and apparatus are disclosed which employ deep ultraviolet (e.g. in the 200 nm to 300 nm spectral range) electron beam pumped wide bandgap semiconductor lasers, incoherent wide bandgap semiconductor light emitting devices, and hollow cathode metal ion lasers to perform non-contact, non-invasive detection of unknown chemical analytes. These deep ultraviolet sources enable dramatic size, weight and power consumption reductions of chemical analysis instruments. In some embodiments, Raman spectroscopic detection methods and apparatus use ultra-narrow-band angle tuning filters, acousto-optic tuning filters, and temperature tuned filters to enable ultra-miniature analyzers for chemical identification. In some embodiments Raman analysis is conducted along with photoluminescence spectroscopy (i.e. fluorescence and/or phosphorescence spectroscopy) to provide high levels of sensitivity and specificity in the same instrument.

Optimal Background Attenuation for Fielded Spectroscopic Detection Systems

International Nuclear Information System (INIS)

Robinson, Sean M.; Ashbaker, Eric D.; Schweppe, John E.; Siciliano, Edward R.

2007-01-01

Radiation detectors are often placed in positions difficult to shield from the effects of terrestrial background gamma radiation. This is particularly true in the case of Radiation Portal Monitor (RPM) systems, as their wide viewing angle and outdoor installations make them susceptible to radiation from the surrounding area. Reducing this source of background can improve gross-count detection capabilities in the current generation of non-spectroscopic RPM's as well as source identification capabilities in the next generation of spectroscopic RPM's. To provide guidance for designing such systems, the problem of shielding a general spectroscopic-capable RPM system from terrestrial gamma radiation is considered. This analysis is carried out by template matching algorithms, to determine and isolate a set of non-threat isotopes typically present in the commerce stream. Various model detector and shielding scenarios are calculated using the Monte-Carlo N Particle (MCNP) computer code. Amounts of nominal-density shielding needed to increase the probability of detection for an ensemble of illicit sources are given. Common shielding solutions such as steel plating are evaluated based on the probability of detection for 3 particular illicit sources of interest, and the benefits are weighed against the incremental cost of shielding. Previous work has provided optimal shielding scenarios for RPMs based on gross-counting measurements, and those same solutions (shielding the internal detector cavity, direct shielding of the ground between the detectors, and the addition of collimators) are examined with respect to their utility to improving spectroscopic detection

PRECISION MEASUREMENTS OF THE CLUSTER RED SEQUENCE USING AN ERROR-CORRECTED GAUSSIAN MIXTURE MODEL

International Nuclear Information System (INIS)

Hao Jiangang; Annis, James; Koester, Benjamin P.; Mckay, Timothy A.; Evrard, August; Gerdes, David; Rykoff, Eli S.; Rozo, Eduardo; Becker, Matthew; Busha, Michael; Wechsler, Risa H.; Johnston, David E.; Sheldon, Erin

2009-01-01

The red sequence is an important feature of galaxy clusters and plays a crucial role in optical cluster detection. Measurement of the slope and scatter of the red sequence are affected both by selection of red sequence galaxies and measurement errors. In this paper, we describe a new error-corrected Gaussian Mixture Model for red sequence galaxy identification. Using this technique, we can remove the effects of measurement error and extract unbiased information about the intrinsic properties of the red sequence. We use this method to select red sequence galaxies in each of the 13,823 clusters in the maxBCG catalog, and measure the red sequence ridgeline location and scatter of each. These measurements provide precise constraints on the variation of the average red galaxy populations in the observed frame with redshift. We find that the scatter of the red sequence ridgeline increases mildly with redshift, and that the slope decreases with redshift. We also observe that the slope does not strongly depend on cluster richness. Using similar methods, we show that this behavior is mirrored in a spectroscopic sample of field galaxies, further emphasizing that ridgeline properties are independent of environment. These precise measurements serve as an important observational check on simulations and mock galaxy catalogs. The observed trends in the slope and scatter of the red sequence ridgeline with redshift are clues to possible intrinsic evolution of the cluster red sequence itself. Most importantly, the methods presented in this work lay the groundwork for further improvements in optically based cluster cosmology.

Precision Measurements of the Cluster Red Sequence using an Error Corrected Gaussian Mixture Model

Energy Technology Data Exchange (ETDEWEB)

Hao, Jiangang; /Fermilab /Michigan U.; Koester, Benjamin P.; /Chicago U.; Mckay, Timothy A.; /Michigan U.; Rykoff, Eli S.; /UC, Santa Barbara; Rozo, Eduardo; /Ohio State U.; Evrard, August; /Michigan U.; Annis, James; /Fermilab; Becker, Matthew; /Chicago U.; Busha, Michael; /KIPAC, Menlo Park /SLAC; Gerdes, David; /Michigan U.; Johnston, David E.; /Northwestern U. /Brookhaven

2009-07-01

The red sequence is an important feature of galaxy clusters and plays a crucial role in optical cluster detection. Measurement of the slope and scatter of the red sequence are affected both by selection of red sequence galaxies and measurement errors. In this paper, we describe a new error corrected Gaussian Mixture Model for red sequence galaxy identification. Using this technique, we can remove the effects of measurement error and extract unbiased information about the intrinsic properties of the red sequence. We use this method to select red sequence galaxies in each of the 13,823 clusters in the maxBCG catalog, and measure the red sequence ridgeline location and scatter of each. These measurements provide precise constraints on the variation of the average red galaxy populations in the observed frame with redshift. We find that the scatter of the red sequence ridgeline increases mildly with redshift, and that the slope decreases with redshift. We also observe that the slope does not strongly depend on cluster richness. Using similar methods, we show that this behavior is mirrored in a spectroscopic sample of field galaxies, further emphasizing that ridgeline properties are independent of environment. These precise measurements serve as an important observational check on simulations and mock galaxy catalogs. The observed trends in the slope and scatter of the red sequence ridgeline with redshift are clues to possible intrinsic evolution of the cluster red-sequence itself. Most importantly, the methods presented in this work lay the groundwork for further improvements in optically-based cluster cosmology.

PSYCHE CPMG-HSQMBC: An NMR Spectroscopic Method for Precise and Simple Measurement of Long-Range Heteronuclear Coupling Constants.

Science.gov (United States)

Timári, István; Szilágyi, László; Kövér, Katalin E

2015-09-28

Among the NMR spectroscopic parameters, long-range heteronuclear coupling constants convey invaluable information on torsion angles relevant to glycosidic linkages of carbohydrates. A broadband homonuclear decoupled PSYCHE CPMG-HSQMBC method for the precise and direct measurement of multiple-bond heteronuclear couplings is presented. The PSYCHE scheme built into the pulse sequence efficiently eliminates unwanted proton-proton splittings from the heteronuclear multiplets so that the desired heteronuclear couplings can be determined simply by measuring frequency differences between peak maxima of pure antiphase doublets. Moreover, PSYCHE CPMG-HSQMBC can provide significant improvement in sensitivity as compared to an earlier Zangger-Sterk-based method. Applications of the proposed pulse sequence are demonstrated for the extraction of (n)J((1)H,(77)Se) and (n)J((1)H,(13)C) values, respectively, in carbohydrates; further extensions can be envisioned in any J-based structural and conformational studies. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Spectroscopic study of low-lying 16N levels

International Nuclear Information System (INIS)

Bardayan, Daniel W.; O'Malley, Patrick; Blackmon, Jeff C.; Chae, K.Y.; Chipps, K.; Cizewski, J.A.; Hatarik, Robert; Jones, K.L.; Kozub, R. L.; Matei, Catalin; Moazen, Brian; Nesaraja, Caroline D.; Pain, Steven D.; Paulauskas, Stanley; Peters, W.A.; Pittman, S.T.; Schmitt, Kyle; Shriner, J.F. Jr.; Smith, Michael Scott

2008-01-01

The magnitude of the 15N(n,gamma)16N reaction rate in asymptotic giant branch stars depends directly on the neutron spectroscopic factors of low-lying 16N levels. A new study of the 15N(d,p)16N reaction is reported populating the ground and first three excited states in 16N. The measured spectroscopic factors are near unity as expected from shell model calculations, resolving a long-standing discrepancy with earlier measurements that had never been confirmed or understood. Updated 15N(n,gamma)16N reaction rates are presented

Methods for otpimum and near optimum disassembly sequencing

NARCIS (Netherlands)

Lambert, A.J.D.; Gupta, S.M.

2008-01-01

This paper considers disassembly sequencing problems subjected to sequence dependent disassembly costs. In practice, the methods for dealing with such problems rely mainly on metaheuristic and heuristic methods, which intrinsically generate suboptimum solutions. Exact methods are NP-hard and

Sequence protein identification by randomized sequence database and transcriptome mass spectrometry (SPIDER-TMS): from manual to automatic application of a 'de novo sequencing' approach.

Science.gov (United States)

Pascale, Raffaella; Grossi, Gerarda; Cruciani, Gabriele; Mecca, Giansalvatore; Santoro, Donatello; Sarli Calace, Renzo; Falabella, Patrizia; Bianco, Giuliana

Sequence protein identification by a randomized sequence database and transcriptome mass spectrometry software package has been developed at the University of Basilicata in Potenza (Italy) and designed to facilitate the determination of the amino acid sequence of a peptide as well as an unequivocal identification of proteins in a high-throughput manner with enormous advantages of time, economical resource and expertise. The software package is a valid tool for the automation of a de novo sequencing approach, overcoming the main limits and a versatile platform useful in the proteomic field for an unequivocal identification of proteins, starting from tandem mass spectrometry data. The strength of this software is that it is a user-friendly and non-statistical approach, so protein identification can be considered unambiguous.

Evolution of containment facilities for spectroscopic analysis at Rockwell Hanford Operations

International Nuclear Information System (INIS)

Hiller, J.M.

1984-01-01

The analysis of radioactive material requires much thought concerning getting the job done while still maintaining a safe working environment. A Rockwell Hanford Operations, several stages of evolution in instrumentation for spectroscopic elemental analysis have evolved, reflecting different philosophies respect to shielding and contamination control. Atomic absorption and inductively coupled plasma emission spectroscopic systems have been used for analyzing samples in support of a fission product recovery plant, nuclear waste processing and characterization programs, and U and Pu separation plants. Design thoughts, criticisms, and lessons learned in 20 years of containment for spectroscopic analysis are presented

The VANDELS ESO spectroscopic survey

Science.gov (United States)

McLure, R. J.; Pentericci, L.; Cimatti, A.; Dunlop, J. S.; Elbaz, D.; Fontana, A.; Nandra, K.; Amorin, R.; Bolzonella, M.; Bongiorno, A.; Carnall, A. C.; Castellano, M.; Cirasuolo, M.; Cucciati, O.; Cullen, F.; De Barros, S.; Finkelstein, S. L.; Fontanot, F.; Franzetti, P.; Fumana, M.; Gargiulo, A.; Garilli, B.; Guaita, L.; Hartley, W. G.; Iovino, A.; Jarvis, M. J.; Juneau, S.; Karman, W.; Maccagni, D.; Marchi, F.; Mármol-Queraltó, E.; Pompei, E.; Pozzetti, L.; Scodeggio, M.; Sommariva, V.; Talia, M.; Almaini, O.; Balestra, I.; Bardelli, S.; Bell, E. F.; Bourne, N.; Bowler, R. A. A.; Brusa, M.; Buitrago, F.; Caputi, K. I.; Cassata, P.; Charlot, S.; Citro, A.; Cresci, G.; Cristiani, S.; Curtis-Lake, E.; Dickinson, M.; Fazio, G. G.; Ferguson, H. C.; Fiore, F.; Franco, M.; Fynbo, J. P. U.; Galametz, A.; Georgakakis, A.; Giavalisco, M.; Grazian, A.; Hathi, N. P.; Jung, I.; Kim, S.; Koekemoer, A. M.; Khusanova, Y.; Le Fèvre, O.; Lotz, J. M.; Mannucci, F.; Maltby, D. T.; Matsuoka, K.; McLeod, D. J.; Mendez-Hernandez, H.; Mendez-Abreu, J.; Mignoli, M.; Moresco, M.; Mortlock, A.; Nonino, M.; Pannella, M.; Papovich, C.; Popesso, P.; Rosario, D. P.; Salvato, M.; Santini, P.; Schaerer, D.; Schreiber, C.; Stark, D. P.; Tasca, L. A. M.; Thomas, R.; Treu, T.; Vanzella, E.; Wild, V.; Williams, C. C.; Zamorani, G.; Zucca, E.

2018-05-01

VANDELS is a uniquely-deep spectroscopic survey of high-redshift galaxies with the VIMOS spectrograph on ESO's Very Large Telescope (VLT). The survey has obtained ultra-deep optical (0.48 studies. Using integration times calculated to produce an approximately constant signal-to-noise ratio (20 motivation, survey design and target selection.

A base composition analysis of natural patterns for the preprocessing of metagenome sequences.

Science.gov (United States)

Bonham-Carter, Oliver; Ali, Hesham; Bastola, Dhundy

2013-01-01

On the pretext that sequence reads and contigs often exhibit the same kinds of base usage that is also observed in the sequences from which they are derived, we offer a base composition analysis tool. Our tool uses these natural patterns to determine relatedness across sequence data. We introduce spectrum sets (sets of motifs) which are permutations of bacterial restriction sites and the base composition analysis framework to measure their proportional content in sequence data. We suggest that this framework will increase the efficiency during the pre-processing stages of metagenome sequencing and assembly projects. Our method is able to differentiate organisms and their reads or contigs. The framework shows how to successfully determine the relatedness between these reads or contigs by comparison of base composition. In particular, we show that two types of organismal-sequence data are fundamentally different by analyzing their spectrum set motif proportions (coverage). By the application of one of the four possible spectrum sets, encompassing all known restriction sites, we provide the evidence to claim that each set has a different ability to differentiate sequence data. Furthermore, we show that the spectrum set selection having relevance to one organism, but not to the others of the data set, will greatly improve performance of sequence differentiation even if the fragment size of the read, contig or sequence is not lengthy. We show the proof of concept of our method by its application to ten trials of two or three freshly selected sequence fragments (reads and contigs) for each experiment across the six organisms of our set. Here we describe a novel and computationally effective pre-processing step for metagenome sequencing and assembly tasks. Furthermore, our base composition method has applications in phylogeny where it can be used to infer evolutionary distances between organisms based on the notion that related organisms often have much conserved code.

Complete Genome Sequences of Isolates of Enterococcus faecium Sequence Type 117, a Globally Disseminated Multidrug-Resistant Clone

Science.gov (United States)

Tedim, Ana P.; Lanza, Val F.; Manrique, Marina; Pareja, Eduardo; Ruiz-Garbajosa, Patricia; Cantón, Rafael; Baquero, Fernando; Tobes, Raquel

2017-01-01

ABSTRACT The emergence of nosocomial infections by multidrug-resistant sequence type 117 (ST117) Enterococcus faecium has been reported in several European countries. ST117 has been detected in Spanish hospitals as one of the main causes of bloodstream infections. We analyzed genome variations of ST117 strains isolated in Madrid and describe the first ST117 closed genome sequences. PMID:28360174

Fitting-free curve resolution of spectroscopic data: Chemometric and physical chemical viewpoints.

Science.gov (United States)

Rajkó, Róbert; Beyramysoltan, Samira; Abdollahi, Hamid; Eőri, János; Pongor, Gábor

2015-08-12

In this paper the authors have investigated spectroscopic data analysis according to a recent development, i.e. the Direct Inversion in the Spectral Subspace (DISS) procedure. DISS is a supervised curve resolution technique, consequently it can be used once the spectra of the potential pure components are known and the experimental spectrum of a chemical mixture is also presented; hence the task is to determine the composition of the unknown chemical mixture. In this paper, the original algorithm of DISS is re-examined and some further critical reasoning and essential developments are provided, including the detailed explanations of the constrained minimization task based on Lagrange multiplier regularization approach. The main conclusion is that the regularization used for DISS is needed because of the possible shifted spectra effect instead of collinearity; and this new property, i.e. treating the mild shifted spectra effect, of DISS can be considered as its main scientific advantage. Copyright © 2015 Elsevier B.V. All rights reserved.

Pre-exposure Prophylaxis Against Human Immunodeficiency Virus

Directory of Open Access Journals (Sweden)

Güle ÇINAR

2018-03-01

Full Text Available According to the Center for Disease Control and Prevention (CDC, there were 2.1 million new human immunodeficiency virus (HIV cases reported worldwide in 2015, which shows that siginificant work needs to be done to prevent the transmission of HIV. Research to date has focused mainly on high-risk men who have sex with men, but many women around the world are also at a high risk for HIV transmissions. In studies conducted, the incidence of HIV infection in high-risk individuals decreases over 90% when high-risk individuals use pre-exposure prophylaxis (PreP HIV, tenofovir disoproxil fumarate-emtricitabine (TDF-FTC safely. Current data and studies on pre-exposure prophylaxis were discussed in this review.

Choice of reference sequence and assembler for alignment of Listeria monocytogenes short-read sequence data greatly influences rates of error in SNP analyses.

Directory of Open Access Journals (Sweden)

Arthur W Pightling

Full Text Available The wide availability of whole-genome sequencing (WGS and an abundance of open-source software have made detection of single-nucleotide polymorphisms (SNPs in bacterial genomes an increasingly accessible and effective tool for comparative analyses. Thus, ensuring that real nucleotide differences between genomes (i.e., true SNPs are detected at high rates and that the influences of errors (such as false positive SNPs, ambiguously called sites, and gaps are mitigated is of utmost importance. The choices researchers make regarding the generation and analysis of WGS data can greatly influence the accuracy of short-read sequence alignments and, therefore, the efficacy of such experiments. We studied the effects of some of these choices, including: i depth of sequencing coverage, ii choice of reference-guided short-read sequence assembler, iii choice of reference genome, and iv whether to perform read-quality filtering and trimming, on our ability to detect true SNPs and on the frequencies of errors. We performed benchmarking experiments, during which we assembled simulated and real Listeria monocytogenes strain 08-5578 short-read sequence datasets of varying quality with four commonly used assemblers (BWA, MOSAIK, Novoalign, and SMALT, using reference genomes of varying genetic distances, and with or without read pre-processing (i.e., quality filtering and trimming. We found that assemblies of at least 50-fold coverage provided the most accurate results. In addition, MOSAIK yielded the fewest errors when reads were aligned to a nearly identical reference genome, while using SMALT to align reads against a reference sequence that is ∼0.82% distant from 08-5578 at the nucleotide level resulted in the detection of the greatest numbers of true SNPs and the fewest errors. Finally, we show that whether read pre-processing improves SNP detection depends upon the choice of reference sequence and assembler. In total, this study demonstrates that researchers

The HITRAN 2008 molecular spectroscopic database

International Nuclear Information System (INIS)

Rothman, L.S.; Gordon, I.E.; Barbe, A.; Benner, D.Chris; Bernath, P.F.; Birk, M.; Boudon, V.; Brown, L.R.; Campargue, A.; Champion, J.-P.; Chance, K.; Coudert, L.H.; Dana, V.; Devi, V.M.; Fally, S.; Flaud, J.-M.

2009-01-01

This paper describes the status of the 2008 edition of the HITRAN molecular spectroscopic database. The new edition is the first official public release since the 2004 edition, although a number of crucial updates had been made available online since 2004. The HITRAN compilation consists of several components that serve as input for radiative-transfer calculation codes: individual line parameters for the microwave through visible spectra of molecules in the gas phase; absorption cross-sections for molecules having dense spectral features, i.e. spectra in which the individual lines are not resolved; individual line parameters and absorption cross-sections for bands in the ultraviolet; refractive indices of aerosols, tables and files of general properties associated with the database; and database management software. The line-by-line portion of the database contains spectroscopic parameters for 42 molecules including many of their isotopologues.

Mid-infrared spectroscopic investigation

International Nuclear Information System (INIS)

Walter, L.; Vergo, N.; Salisbury, J.W.

1987-01-01

Mid-infrared spectroscopic research efforts are discussed. The development of a new instrumentation to permit advanced measurements in the mid-infrared region of the spectrum, the development of a special library of well-characterized mineral and rock specimens for interpretation of remote sensing data, and cooperative measurements of the spectral signatures of analogues of materials that may be present on the surfaces of asteroids, planets or their Moons are discussed

Chemical mapping of pharmaceutical cocrystals using terahertz spectroscopic imaging.

Science.gov (United States)

Charron, Danielle M; Ajito, Katsuhiro; Kim, Jae-Young; Ueno, Yuko

2013-02-19

Terahertz (THz) spectroscopic imaging is a promising technique for distinguishing pharmaceuticals of similar molecular composition but differing crystal structures. Physicochemical properties, for instance bioavailability, are manipulated by altering a drug's crystal structure through methods such as cocrystallization. Cocrystals are molecular complexes having crystal structures different from those of their pure components. A technique for identifying the two-dimensional distribution of these alternate forms is required. Here we present the first demonstration of THz spectroscopic imaging of cocrystals. THz spectra of caffeine-oxalic acid cocrystal measured at low temperature exhibit sharp peaks, enabling us to visualize the cocrystal distribution in nonuniform tablets. The cocrystal distribution was clearly identified using THz spectroscopic data, and the cocrystal concentration was calculated with 0.3-1.3% w/w error from the known total concentration. From this result, THz spectroscopy allows quantitative chemical mapping of cocrystals and offers researchers and drug developers a new analytical tool.

Functional compensation of motor function in pre-symptomatic Huntington's disease

DEFF Research Database (Denmark)

Klöppel, Stefan; Draganski, Bogdan; Siebner, Hartwig R

2009-01-01

the compensatory mechanisms that underlie the phenomenon of retained motor function in the presence of degenerative change. Fifteen pre-symptomatic gene carriers and 12 matched controls performed button presses paced by a metronome at either 0.5 or 2 Hz with four fingers of the right hand whilst being scanned...... with functional magnetic resonance imaging. Subjects pressed buttons either in the order of a previously learnt 10-item finger sequence, from left to right, or kept still. Error rates ranged from 2% to 7% in the pre-symptomatic gene carriers and from 0.5% to 4% in controls, depending on the condition...

Googling DNA sequences on the World Wide Web.

Science.gov (United States)

Hajibabaei, Mehrdad; Singer, Gregory A C

2009-11-10

New web-based technologies provide an excellent opportunity for sharing and accessing information and using web as a platform for interaction and collaboration. Although several specialized tools are available for analyzing DNA sequence information, conventional web-based tools have not been utilized for bioinformatics applications. We have developed a novel algorithm and implemented it for searching species-specific genomic sequences, DNA barcodes, by using popular web-based methods such as Google. We developed an alignment independent character based algorithm based on dividing a sequence library (DNA barcodes) and query sequence to words. The actual search is conducted by conventional search tools such as freely available Google Desktop Search. We implemented our algorithm in two exemplar packages. We developed pre and post-processing software to provide customized input and output services, respectively. Our analysis of all publicly available DNA barcode sequences shows a high accuracy as well as rapid results. Our method makes use of conventional web-based technologies for specialized genetic data. It provides a robust and efficient solution for sequence search on the web. The integration of our search method for large-scale sequence libraries such as DNA barcodes provides an excellent web-based tool for accessing this information and linking it to other available categories of information on the web.

The SFR-M∗ main sequence archetypal star-formation history and analytical models

Science.gov (United States)

Ciesla, L.; Elbaz, D.; Fensch, J.

2017-12-01

The star-formation history (SFH) of galaxies is a key assumption to derive their physical properties and can lead to strong biases. In this work, we derive the SFH of main sequence (MS) galaxies and show how the peak SFH of a galaxy depends on its seed mass at, for example, z = 5. This seed mass reflects the galaxy's underlying dark matter (DM) halo environment. We show that, following the MS, galaxies undergo a drastic slow down of their stellar mass growth after reaching the peak of their SFH. According to abundance matching, these masses correspond to hot and massive DM halos which state could result in less efficient gas inflows on the galaxies and thus could be the origin of limited stellar mass growth. As a result, we show that galaxies, still on the MS, can enter the passive region of the UVJ diagram while still forming stars. The best fit to the MS SFH is provided by a right skew peak function for which we provide parameters depending on the seed mass of the galaxy. The ability of the classical analytical SFHs to retrieve the star-formation rate (SFR) of galaxies from spectral energy distribution (SED) fitting is studied. Due to mathematical limitations, the exponentially declining and delayed SFH struggle to model high SFR, which starts to be problematic at z > 2. The exponentially rising and log-normal SFHs exhibit the opposite behavior with the ability to reach very high SFR, and thus model starburst galaxies, but they are not able to model low values such as those expected at low redshift for massive galaxies. By simulating galaxies SED from the MS SFH, we show that these four analytical forms recover the SFR of MS galaxies with an error dependent on the model and the redshift. They are, however, sensitive enough to probe small variations of SFR within the MS, with an error ranging from 5 to 40% depending on the SFH assumption and redshift; but all the four fail to recover the SFR of rapidly quenched galaxies. However, these SFHs lead to an artificial

Spectroscopic methods for characterization of nuclear fuels

International Nuclear Information System (INIS)

Sastry, M.D.

1999-01-01

Spectroscopic techniques have contributed immensely in the characterisation and speciation of materials relevant to a variety of applications. These techniques have time tested credentials and continue to expand into newer areas. In the field of nuclear fuel fabrication, atomic spectroscopic methods are used for monitoring the trace metallic constituents in the starting materials and end product, and for monitoring process pick up. The current status of atomic spectroscopic methods for the determination of trace metallic constituents in nuclear fuel materials will be briefly reviewed and new approaches will be described with a special emphasis on inductively coupled plasma techniques and ETV-ICP-AES hyphenated techniques. Special emphasis will also be given in highlighting the importance of chemical separation procedures for the optimum utilization of potential of ICP. The presentation will also include newer techniques like Photo Acoustic Spectroscopy, and Electron Paramagnetic Resonance (EPR) Imaging. PAS results on uranium and plutonium oxides will be described with a reference to the determination of U 4+ /U 6+ concentration in U 3 O 8 . EPR imaging techniques for speciation and their spatial distribution in solids will be described and its potential use for Gd 3+ containing UO 2 pellets (used for flux flattening) will be highlighted. (author)

Thermophysical and spectroscopic studies of room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate in Tritons

International Nuclear Information System (INIS)

Chaudhary, Ganga Ram; Bansal, Shafila; Mehta, S.K.; Ahluwalia, A.S.

2012-01-01

Highlights: ► Thermophysical studies of new formulations of [BMIM][PF 6 ]+TX(45,100) have been made. ► Strong intermolecular interactions between [BMIM][PF 6 ] and TX (45, 100) is observed. ► Magnitude of interactions increases with the addition of oxyethylene groups in TX. ► With rise in temperature, intermolecular interactions increases. ► Spectroscopic studies show that interactions are via aromatic rings of RTIL and TX. - Abstract: The thermophysical properties viz. density ρ, speed of sound u, and specific conductivity κ of pure room temperature ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) and its binary formulations with Triton X-45 and Triton X-100 have been studied over the entire composition range at different temperatures (293.15 to 323.15) K. Excess molar volume V E , deviation in isentropic compressibility ΔK S , partial molar excess volume V i E , deviation in partial molar isentropic compressibility ΔK S,i , deviation in specific conductivity Δκ have also been estimated and analysed. Spectroscopic properties (IR, 1 H and 13 C NMR) of these mixtures have been investigated in order to understand the structural and interactional behaviour of formulations studied. The magnitude of interactions between the two components increases with addition of number of oxyethylene groups in Tritons and with rise in temperature. Spectroscopic measurements indicate that interactions are mainly taking place through the five member ring of room temperature ionic liquid and six member ring of Tritons.

The present-day chemical composition of the SMC from UVES spectra of the sharp-lined, B-type dwarf AV 304

NARCIS (Netherlands)

Rolleston, WRJ; Venn, K; Tolstoy, E; Dufton, PL

High-resolution spectroscopic VLT/UVES observations are presented for the B-type main-sequence star, AV 304, in the Small Magellanic Cloud (SMC). These spectra have been analysed using LTE model-atmosphere techniques, to derive stellar atmospheric parameters and chemical compositions. As AV 304 is

IDENTIFICATION OF THE LITHIUM DEPLETION BOUNDARY AND AGE OF THE SOUTHERN OPEN CLUSTER BLANCO 1

International Nuclear Information System (INIS)

Cargile, P. A.; James, D. J.; Jeffries, R. D.

2010-01-01

We present results from a spectroscopic study of the very low mass members of the Southern open cluster Blanco 1 using the Gemini-N telescope. We obtained intermediate resolution (R ∼ 4400) GMOS spectra for 15 cluster candidate members with I ∼ 14-20 mag, and employed a series of membership criteria-proximity to the cluster's sequence in an I/I - K s color-magnitude diagram (CMD), kinematics agreeing with the cluster systemic motion, magnetic activity as a youth indicator-to classify 10 of these objects as probable cluster members. For these objects, we searched for the presence of the Li I 6708 A feature to identify the lithium depletion boundary (LDB) in Blanco 1. The I/I - K s CMD shows a clear mass segregation in the Li distribution along the cluster sequence; namely, all higher mass stars are found to be Li poor, while lower mass stars are found to be Li rich. The division between Li-poor and Li-rich (i.e., the LDB) in Blanco 1 is found at I = 18.78 ± 0.24 and I - K s = 3.05 ± 0.10. Using current pre-main-sequence evolutionary models, we determine an LDB age of 132 ± 24 Myr. Comparing our derived LDB age to upper-main-sequence isochrone ages for Blanco 1, as well as for other open clusters with identified LDBs, we find good chronometric consistency when using stellar evolution models that incorporate a moderate degree of convective core overshoot.

Photometric search for variable stars in the young open cluster Berkeley 59

Science.gov (United States)

Lata, Sneh; Pandey, A. K.; Maheswar, G.; Mondal, Soumen; Kumar, Brijesh

2011-12-01

We present the time series photometry of stars located in the extremely young open cluster Berkeley 59. Using the 1.04-m telescope at Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital, we have identified 42 variables in a field of ˜13 × 13 arcmin2 around the cluster. The probable members of the cluster have been identified using a (V, V-I) colour-magnitude diagram and a (J-H, H-K) colour-colour diagram. 31 variables have been found to be pre-main-sequence stars associated with the cluster. The ages and masses of the pre-main-sequence stars have been derived from the colour-magnitude diagram by fitting theoretical models to the observed data points. The ages of the majority of the probable pre-main-sequence variable candidates range from 1 to 5 Myr. The masses of these pre-main-sequence variable stars have been found to be in the range of ˜0.3 to ˜3.5 M⊙, and these could be T Tauri stars. The present statistics reveal that about 90 per cent T Tauri stars have period dispersal of the discs of relatively massive stars.

Post-main-sequence Evolution of Icy Minor Planets. II. Water Retention and White Dwarf Pollution around Massive Progenitor Stars

Energy Technology Data Exchange (ETDEWEB)

Malamud, Uri; Perets, Hagai B., E-mail: uri.mal@tx.technion.ac.il, E-mail: hperets@physics.technion.ac.il [Department of Physics, Technion (Israel)

2017-06-10

Most studies suggest that the pollution of white dwarf (WD) atmospheres arises from the accretion of minor planets, but the exact properties of polluting material, and in particular the evidence for water in some cases, are not yet understood. Here we study the water retention of small icy bodies in exo-solar planetary systems, as their respective host stars evolve through and off the main sequence and eventually become WDs. We explore, for the first time, a wide range of star masses and metallicities. We find that the mass of the WD progenitor star is of crucial importance for the retention of water, while its metallicity is relatively unimportant. We predict that minor planets around lower-mass WD progenitors would generally retain more water and would do so at closer distances from the WD than compared with high-mass progenitors. The dependence of water retention on progenitor mass and other parameters has direct implications for the origin of observed WD pollution, and we discuss how our results and predictions might be tested in the future as more observations of WDs with long cooling ages become available.

Exome sequencing and genetic testing for MODY.

Directory of Open Access Journals (Sweden)

Stefan Johansson

Full Text Available Genetic testing for monogenic diabetes is important for patient care. Given the extensive genetic and clinical heterogeneity of diabetes, exome sequencing might provide additional diagnostic potential when standard Sanger sequencing-based diagnostics is inconclusive.The aim of the study was to examine the performance of exome sequencing for a molecular diagnosis of MODY in patients who have undergone conventional diagnostic sequencing of candidate genes with negative results.We performed exome enrichment followed by high-throughput sequencing in nine patients with suspected MODY. They were Sanger sequencing-negative for mutations in the HNF1A, HNF4A, GCK, HNF1B and INS genes. We excluded common, non-coding and synonymous gene variants, and performed in-depth analysis on filtered sequence variants in a pre-defined set of 111 genes implicated in glucose metabolism.On average, we obtained 45 X median coverage of the entire targeted exome and found 199 rare coding variants per individual. We identified 0-4 rare non-synonymous and nonsense variants per individual in our a priori list of 111 candidate genes. Three of the variants were considered pathogenic (in ABCC8, HNF4A and PPARG, respectively, thus exome sequencing led to a genetic diagnosis in at least three of the nine patients. Approximately 91% of known heterozygous SNPs in the target exomes were detected, but we also found low coverage in some key diabetes genes using our current exome sequencing approach. Novel variants in the genes ARAP1, GLIS3, MADD, NOTCH2 and WFS1 need further investigation to reveal their possible role in diabetes.Our results demonstrate that exome sequencing can improve molecular diagnostics of MODY when used as a complement to Sanger sequencing. However, improvements will be needed, especially concerning coverage, before the full potential of exome sequencing can be realized.

Evolution of containment facilities for spectroscopic analysis at Rockwell Hanford Operations

International Nuclear Information System (INIS)

Hiller, J.M.

1984-01-01

The analysis of radioactive material requires much thought concerning getting the job done while still maintaining a safe working environment. At Rockwell Hanford Operations, we have gone through several stages of evolution in instrumentation for spectroscopic elemental analysis, reflecting different philosophies with respect to shielding and contamination control. Atomic absorption and inductively coupled plasma emission spectroscopic systems have been used for analyzing samples in support of a fission product recovery plant, nuclear waste processing and characterization programs, and U and Pu separation plants. Design thoughts, criticisms, and lessons learned in 20 years of containment for spectroscopic analysis are presented. 3 refs., 6 figs., 2 tabs

Presence of Helicobacter pylori in a Mexican Pre-Columbian Mummy

Directory of Open Access Journals (Sweden)

Cerbón Marco A

2008-07-01

Full Text Available Abstract Background Recent studies showed that Helicobacter pylori existed in the New World prior to the arrival of Columbus. The purpose of the present study was to detect the presence of Helicobacter pylori in pre-Columbian mummies from Northern Mexico. Methods Six samples were studied (four samples of gastric remains, tongue-soft palate, and brain remained as negative controls from two of the six naturally mummified corpses studied (adult male and infant male. Samples were taken from tissues suitable for DNA amplification by Polymerase chain reaction (PCR. DNA was extracted and H. pylori detection was carried out by PCR and hybridized with the pHp probe from 16S rRNA gene. The purified PCR products were cloned and sequenced in both directions. DNA sequences were analyzed with ALIGN and BLAST software. A second amplification was performed using ureB gene by real-time PCR. Results From four samples of gastric remnant, only two were H. pylori-positive for amplification of a 109 bp DNA fragment; the remaining two were negative, as were the tongue-soft palate and the brain biopsies as well. These PCR products were hybridized with a pHp probe. Nucleotide sequence analysis showed homology with H. pylori in 98 of 99% when compared with the gene bank nucleotide sequence. Only one sample of gastric remnant H. pylori-positive with 16S rRNA gene was also positive for ureB gene from H. pylori. Conclusion This data supported infection with H. pylori in Mexican pre-Columbian mummies dating from approximately 1,350 AC.

Geochemical study of main elements and trace elements in soils of three profiles in the state of Santa Catarina

International Nuclear Information System (INIS)

Santelli, R.E.

1985-01-01

The total concentrations of the main components (Si, Al, Fe, Ca, Mg, Mn, Ti, Na and K) and of nine trace elements (Ba, Co, Cu, La, Li, Mo, Ni, V and Zn are measured. The elements are determined by several atomic absorption and emission spectroscopic methods. Some properties such as granulometry, mineralogy of the clay fraction, organic matter, etc, are studied. (M.J.C.) [pt

In Vivo H MR spectroscopic imaging of human brain

International Nuclear Information System (INIS)

Choe, Bo Young; Suh, Tae Suk; Choi, Kyo Ho; Bahk, Yong Whee; Shinn, Kyung Sub

1994-01-01

To evaluate the spatial distribution of various proton metabolites in the human brain with use of water-suppressed in vivo H MR spectroscopic imaging (MRSI) technique. All of water-suppressed in vivo H MRSI were performed on 1.5 T whole-body MRI/MRS system using Stimulated Echo Acquisition Method (STEAM) Chemical Shift Imaging (CSI) pulse sequence. T1-weighted MR images were used for CSI field of view (FOV; 24 cm). Voxel size of 1.5 cm 3 was designated from the periphery of the brain which was divided by 1024 X 16 X 16 data points. Metabolite images of N-acetylaspartate (NAA), creatine/ phosphocreatine (Cr) + choline/phosphocholine (Cho), and complex of γ-aminobutyric acid (GABA) + glutamate (Glu) were obtained on the human brain. Our preliminary study suggests that in vivo H MRSI could provide the metabolite imaging to compensate for hypermetabolism on Positron Emission Tomography (PET) scans on the basis of the metabolic informations on brain tissues. The unique ability of in vivo H MRSI to offer noninvasive information about tissue biochemistry in disease states will stimulate on clinical research and disease diagnosis

Universal relation between spectroscopic constants

Indian Academy of Sciences (India)

(3) The author has used eq. (6) of his paper to calculate De. This relation leads to a large deviation from the correct value depending upon the extent to which experimental values are known. Guided by this fact, in our work, we used experimentally observed De values to derive the relation between spectroscopic constants.

An important step forward in continuous spectroscopic imaging of ionising radiations using ASICs

Energy Technology Data Exchange (ETDEWEB)

Fessler, P. [11 rue Rabelais, 92170 Vanves (France); Coffin, J. [Institut de Recherches Subatomiques, B.P. 28, 67037 Strasbourg (France); Eberle, H. [Institut de Recherches Subatomiques, B.P. 28, 67037 Strasbourg (France); Raad Iseli, C. de [Smart Silicon Systems SA, Ch. de la Graviere 6, CH-1007 Lausanne (Switzerland); Hilt, B. [Universite de Haute-Alsace, GRPHE, 61, rue Albert Camus, 68093 Mulhouse (France); Huss, D. [Universite de Haute-Alsace, GRPHE, 61, rue Albert Camus, 68093 Mulhouse (France); Krummenacher, F. [Smart Silicon Systems SA, Ch. de la Graviere 6, CH-1007 Lausanne (Switzerland); Lutz, J.R. [Institut de Recherches Subatomiques, B.P. 28, 67037 Strasbourg (France); Prevot, G. [Institut de Recherches Subatomiques, B.P. 28, 67037 Strasbourg (France); Renouprez, A. [Institut de Recherche sur la Catalyse, 2 Avenue Albert Einstein, 69626 Villeurbanne (France); Sigward, M.H. [Institut de Recherches Subatomiques, B.P. 28, 67037 Strasbourg (France); Schwaller, B. [Universite de Haute-Alsace, GRPHE, 61, rue Albert Camus, 68093 Mulhouse (France); Voltolini, C. [Institut de Recherches Subatomiques, B.P. 28, 67037 Strasbourg (France)

1999-01-21

Characterization results are given for an original ASIC allowing continuous acquisition of ionising radiation images in spectroscopic mode. Ionising radiation imaging in general and spectroscopic imaging in particular must primarily be guided by the attempt to decrease statistical noise, which requires detection systems designed to allow very high counting rates. Any source of dead time must therefore be avoided. Thus, the use of on-line corrections of the inevitable dispersion of characteristics between the large number of electronic channels of the detection system, shall be precluded. Without claiming to achieve ultimate noise levels, the work described is focused on how to prevent good individual acquisition channel noise performance from being totally destroyed by the dispersion between channels without introducing dead times. With this goal, we developed an automatic charge amplifier output voltage offset compensation system which operates regardless of the cause of the offset (detector or electronic). The main performances of the system are the following: the input equivalent noise charge is 190 e rms (input non connected, peaking time 500 ns), the highest gain is 255 mV/fC, the peaking time is adjustable between 200 ns and 2 {mu}s and the power consumption is 10 mW per channel. The agreement between experimental data and theoretical simulation results is excellent.

An important step forward in continuous spectroscopic imaging of ionising radiations using ASICs

International Nuclear Information System (INIS)

Fessler, P.; Coffin, J.; Eberle, H.; Raad Iseli, C. de; Hilt, B.; Huss, D.; Krummenacher, F.; Lutz, J.R.; Prevot, G.; Renouprez, A.; Sigward, M.H.; Schwaller, B.; Voltolini, C.

1999-01-01

Characterization results are given for an original ASIC allowing continuous acquisition of ionising radiation images in spectroscopic mode. Ionising radiation imaging in general and spectroscopic imaging in particular must primarily be guided by the attempt to decrease statistical noise, which requires detection systems designed to allow very high counting rates. Any source of dead time must therefore be avoided. Thus, the use of on-line corrections of the inevitable dispersion of characteristics between the large number of electronic channels of the detection system, shall be precluded. Without claiming to achieve ultimate noise levels, the work described is focused on how to prevent good individual acquisition channel noise performance from being totally destroyed by the dispersion between channels without introducing dead times. With this goal, we developed an automatic charge amplifier output voltage offset compensation system which operates regardless of the cause of the offset (detector or electronic). The main performances of the system are the following: the input equivalent noise charge is 190 e rms (input non connected, peaking time 500 ns), the highest gain is 255 mV/fC, the peaking time is adjustable between 200 ns and 2 μs and the power consumption is 10 mW per channel. The agreement between experimental data and theoretical simulation results is excellent

Using auditory pre-information to solve the cocktail-party problem: electrophysiological evidence for age-specific differences.

Science.gov (United States)

Getzmann, Stephan; Lewald, Jörg; Falkenstein, Michael

2014-01-01

Speech understanding in complex and dynamic listening environments requires (a) auditory scene analysis, namely auditory object formation and segregation, and (b) allocation of the attentional focus to the talker of interest. There is evidence that pre-information is actively used to facilitate these two aspects of the so-called "cocktail-party" problem. Here, a simulated multi-talker scenario was combined with electroencephalography to study scene analysis and allocation of attention in young and middle-aged adults. Sequences of short words (combinations of brief company names and stock-price values) from four talkers at different locations were simultaneously presented, and the detection of target names and the discrimination between critical target values were assessed. Immediately prior to speech sequences, auditory pre-information was provided via cues that either prepared auditory scene analysis or attentional focusing, or non-specific pre-information was given. While performance was generally better in younger than older participants, both age groups benefited from auditory pre-information. The analysis of the cue-related event-related potentials revealed age-specific differences in the use of pre-cues: Younger adults showed a pronounced N2 component, suggesting early inhibition of concurrent speech stimuli; older adults exhibited a stronger late P3 component, suggesting increased resource allocation to process the pre-information. In sum, the results argue for an age-specific utilization of auditory pre-information to improve listening in complex dynamic auditory environments.

Using auditory pre-information to solve the cocktail-party problem: electrophysiological evidence for age-specific differences

Directory of Open Access Journals (Sweden)

Stephan eGetzmann

2014-12-01

Full Text Available Speech understanding in complex and dynamic listening environments requires (a auditory scene analysis, namely auditory object formation and segregation, and (b allocation of the attentional focus to the talker of interest. There is evidence that pre-information is actively used to facilitate these two aspects of the so-called cocktail-party problem. Here, a simulated multi-talker scenario was combined with electroencephalography to study scene analysis and allocation of attention in young and middle-aged adults. Sequences of short words (combinations of brief company names and stock-price values from four talkers at different locations were simultaneously presented, and the detection of target names and the discrimination between critical target values were assessed. Immediately prior to speech sequences, auditory pre-information was provided via cues that either prepared auditory scene analysis or attentional focusing, or non-specific pre-information was given. While performance was generally better in younger than older participants, both age groups benefited from auditory pre-information. The analysis of the cue-related event-related potentials revealed age-specific differences in the use of pre-cues: Younger adults showed a pronounced N2 component, suggesting early inhibition of concurrent speech stimuli; older adults exhibited a stronger late P3 component, suggesting increased resource allocation to process the pre-information. In sum, the results argue for an age-specific utilization of auditory pre-information to improve listening in complex dynamic auditory environments.

A Spectroscopic and Photometric Study of Gravitational Microlensing Events

Science.gov (United States)

Kane, Stephen R.

2000-08-01

results presented in this thesis are from observations of 34 microlensing events over three consecutive bulge seasons. These results are presented along with a discussion of the observations and the data reduction procedures. The colour-magnitude diagrams indicate that the microlensed sources are main sequence and red clump giant stars. Most of the events appear to exhibit standard Paczynski point source - point lens curves whilst a few deviate significantly from the standard model. Various microlensing models that include anomalous structure are fitted to a selection of the observed events resulting in the discovery of a possible binary source event. These fitted events are used to estimate the sensitivity to extra-solar planets and it is found that the sampling rate for these events was insufficient by about a factor of 7.5 for detecting a Jupiter-mass planet. This result assumes that deviations of 5% can be reliably detected. If microlensing is caused predominantly by bulge stars, as has been suggested by Kiraga and Paczynski, the lensed stars should have larger extinction than other observed stars since they would preferentially be located at the far side of the Galactic bulge. Hence, spectroscopy of Galactic microlensing events may be used as a tool for studying the kinematics and extinction effects in the Galactic bulge. The spectroscopic work in this project involved using Kurucz model spectra to create theoretical extinction effects for various spectral classes towards the Galactic centre. These extinction effects are then used to interpret spectroscopic data taken with the 3.6 m ESO telescope. These data consist of a sample of microlensed stars towards the Galactic bulge and are used to derive the extinction offsets of the lensed source with respect to the average population and a measurement of the fraction of bulge-bulge lensing is made. Hence, it is shown statistically that the microlensed sources are generally located on the far side of the Galactic bulge

Strain Anomalies during an Earthquake Sequence in the South Iceland Seismic Zone

Science.gov (United States)

Arnadottir, T.; Haines, A. J.; Geirsson, H.; Hreinsdottir, S.

2017-12-01

The South Iceland Seismic Zone (SISZ) accommodates E-W translation due to oblique spreading between the North American/Hreppar microplate and Eurasian plate, in South Iceland. Strain is released in the SISZ during earthquake sequences that last days to years, at average intervals of 80-100 years. The SISZ is currently in the midst of an earthquake sequence that started with two M6.5 earthquakes in June 2000, and continued with two M6 earthquakes in May 2008. Estimates of geometric strain accumulation, and seismic strain release in these events indicate that they released at most only half of the strain accumulated since the last earthquake cycle in 1896-1912. Annual GPS campaigns and continuous measurements during 2001-2015 were used to calculate station velocities and strain rates from a new method using the vertical derivatives of horizontal stress (VDoHS). This new method allows higher resolution of strain rates than other (older) approaches, as the strain rates are estimated by integrating VDoHS rates obtained by inversion rather than differentiating interpolated GPS velocities. Estimating the strain rates for eight 1-2 year intervals indicates temporal and spatial variation of strain rates in the SISZ. In addition to earthquake faulting, the strain rates in the SISZ are influenced by anthropogenic signals due to geothermal exploitation, and magma movements in neighboring volcanoes - Hekla and Eyjafjallajökull. Subtle signals of post-seismic strain rate changes are seen following the June 2000 M6.5 main shocks, but interestingly, much larger strain rate variations are observed after the two May 2008 M6 main shocks. A prominent strain anomaly is evident in the epicentral area prior to the May 2008 earthquake sequence. The strain signal persists over at least 4 years in the epicentral area, leading up to the M6 main shocks. The strain is primarily extension in ESE-WNW direction (sub-parallel to the direction of plate spreading), but overall shear across the N

RAMAN SPECTROSCOPIC STUDY ON PREDICTION OF TREATMENT RESPONSE IN CERVICAL CANCERS

Directory of Open Access Journals (Sweden)

S. RUBINA

2013-04-01

Full Text Available Concurrent chemoradiotherapy (CCRT is the choice of treatment for locally advanced cervical cancers; however, tumors exhibit diverse response to treatment. Early prediction of tumor response leads to individualizing treatment regimen. Response evaluation criteria in solid tumors (RECIST, the current modality of tumor response assessment, is often subjective and carried out at the first visit after treatment, which is about four months. Hence, there is a need for better predictive tool for radioresponse. Optical spectroscopic techniques, sensitive to molecular alteration, are being pursued as potential diagnostic tools. Present pilot study aims to explore the fiber-optic-based Raman spectroscopy approach in prediction of tumor response to CCRT, before taking up extensive in vivo studies. Ex vivo Raman spectra were acquired from biopsies collected from 11 normal (148 spectra, 16 tumor (201 spectra and 13 complete response (151 CR spectra, one partial response (8 PR spectra and one nonresponder (8 NR spectra subjects. Data was analyzed using principal component linear discriminant analysis (PC-LDA followed by leave-one-out cross-validation (LOO-CV. Findings suggest that normal tissues can be efficiently classified from both pre- and post-treated tumor biopsies, while there is an overlap between pre- and post-CCRT tumor tissues. Spectra of CR, PR and NR tissues were subjected to principal component analysis (PCA and a tendency of classification was observed, corroborating previous studies. Thus, this study further supports the feasibility of Raman spectroscopy in prediction of tumor radioresponse and prospective noninvasive in vivo applications.

Influence of reaction time on the structure of polyaniline synthesized on a pre-pilot scale

Directory of Open Access Journals (Sweden)

Maria Alice Carvalho Mazzeu

Full Text Available Abstract The aim of this work is to follow the structural variations of polyaniline (PAni obtained by chemical oxidation on a pre-pilot scale, with different reaction times. Synthesis of PAni is well known, but when it is carried out on a pre-pilot scale, several factors can lead to structural changes and understanding these changes is important to improve controls on the synthesis process. The polymers formed were characterized by spectroscopic techniques (Raman spectroscopy, Fourier Transform Infrared - FTIR and UV-Visible. Degree of oxidation and yield were calculated for each reaction time. The analysis by FTIR, the calculated degree of oxidation and the yield showed significant changes in polymer structure at reaction times of 65 and 80 min. This result was attributed to the excessive oxidation of PAni, with the breaking of its polymer chain. The changes observed in the structure of PAni gave subsidies to the optimization of the process of obtaining polyaniline by chemical synthesis.

Geoseq: a tool for dissecting deep-sequencing datasets

Directory of Open Access Journals (Sweden)

Homann Robert

2010-10-01

Full Text Available Abstract Background Datasets generated on deep-sequencing platforms have been deposited in various public repositories such as the Gene Expression Omnibus (GEO, Sequence Read Archive (SRA hosted by the NCBI, or the DNA Data Bank of Japan (ddbj. Despite being rich data sources, they have not been used much due to the difficulty in locating and analyzing datasets of interest. Results Geoseq http://geoseq.mssm.edu provides a new method of analyzing short reads from deep sequencing experiments. Instead of mapping the reads to reference genomes or sequences, Geoseq maps a reference sequence against the sequencing data. It is web-based, and holds pre-computed data from public libraries. The analysis reduces the input sequence to tiles and measures the coverage of each tile in a sequence library through the use of suffix arrays. The user can upload custom target sequences or use gene/miRNA names for the search and get back results as plots and spreadsheet files. Geoseq organizes the public sequencing data using a controlled vocabulary, allowing identification of relevant libraries by organism, tissue and type of experiment. Conclusions Analysis of small sets of sequences against deep-sequencing datasets, as well as identification of public datasets of interest, is simplified by Geoseq. We applied Geoseq to, a identify differential isoform expression in mRNA-seq datasets, b identify miRNAs (microRNAs in libraries, and identify mature and star sequences in miRNAS and c to identify potentially mis-annotated miRNAs. The ease of using Geoseq for these analyses suggests its utility and uniqueness as an analysis tool.

Inverted temperature sequences: role of deformation partitioning

Science.gov (United States)

Grujic, D.; Ashley, K. T.; Coble, M. A.; Coutand, I.; Kellett, D.; Whynot, N.

2015-12-01

The inverted metamorphism associated with the Main Central thrust zone in the Himalaya has been historically attributed to a number of tectonic processes. Here we show that there is actually a composite peak and deformation temperature sequence that formed in succession via different tectonic processes. The deformation partitioning seems to the have played a key role, and the magnitude of each process has varied along strike of the orogen. To explain the formation of the inverted metamorphic sequence across the Lesser Himalayan Sequence (LHS) in eastern Bhutan, we used Raman spectroscopy of carbonaceous material (RSCM) to determine the peak metamorphic temperatures and Ti-in-quartz thermobarometry to determine the deformation temperatures combined with thermochronology including published apatite and zircon U-Th/He and fission-track data and new 40Ar/39Ar dating of muscovite. The dataset was inverted using 3D-thermal-kinematic modeling to constrain the ranges of geological parameters such as fault geometry and slip rates, location and rates of localized basal accretion, and thermal properties of the crust. RSCM results indicate that there are two peak temperature sequences separated by a major thrust within the LHS. The internal temperature sequence shows an inverted peak temperature gradient of 12 °C/km; in the external (southern) sequence, the peak temperatures are constant across the structural sequence. Thermo-kinematic modeling suggest that the thermochronologic and thermobarometric data are compatible with a two-stage scenario: an Early-Middle Miocene phase of fast overthrusting of a hot hanging wall over a downgoing footwall and inversion of the synkinematic isotherms, followed by the formation of the external duplex developed by dominant underthrusting and basal accretion. To reconcile our observations with the experimental data, we suggest that pervasive ductile deformation within the upper LHS and along the Main Central thrust zone at its top stopped at

Bio-medical X-ray imaging with spectroscopic pixel detectors

CERN Document Server

Butler, A P H; Tipples, R; Cook, N; Watts, R; Meyer, J; Bell, A J; Melzer, T R; Butler, P H

2008-01-01

The aim of this study is to review the clinical potential of spectroscopic X-ray detectors and to undertake a feasibility study using a novel detector in a clinical hospital setting. Detectors currently in development, such as Medipix-3, will have multiple energy thresholds allowing for routine use of spectroscopic bio-medical imaging. We have coined the term MARS (Medipix All Resolution System) for bio-medical images that provide spatial, temporal, and energy information. The full clinical significance of spectroscopic X-ray imaging is difficult to predict but insights can be gained by examining both image reconstruction artifacts and the current uses of dual-energy techniques. This paper reviews the known uses of energy information in vascular imaging and mammography, clinically important fields. It then presents initial results from using Medipix-2, to image human tissues within a clinical radiology department. Detectors currently in development, such as Medipix-3, will have multiple energy thresholds allo...

Sir Robert Sidney’s Poems Revisited: the alternative sequence

OpenAIRE

Relvas, Maria de Jesus C.

1997-01-01

The essay approaches the lyric sequence written by Sir Robert Sidney (1563-1626) in the Elizabethan age, by mainly exploring its unique formal structure, which encloses an alternative sequence formed by a re-numbering of several poems.

Serum 8-isoprostane increased in pre-eclampsia

Directory of Open Access Journals (Sweden)

Besari Adi Pramono

2012-04-01

Full Text Available Background The main causes of maternal mortality in Indonesia are pre-eclampsia, hemorrhage, and infection. Oxidative stress has a primary role in pre-eclampsia and one of its parameters is 8-isoprostane serum level. The objective of this study is to measure 8-isoprostane and to analyze the relationship between 8-isoprostane level and birth weight in pre-eclampsia. Methods A cross-sectional study involving 23 pre-eclampsia and 29 normotensive pregnant women with normal or cesarean delivery at Dr. Kariadi Hospital Semarang from January to May 2011. Collected maternal blood samples were assessed for 8-Isoprostane levels by means of a specific ELISA kit. Neonatal birth weight was measured immediately after delivery by means of calibrated baby scales. Differences in 8-isoprostane levels between pre-eclampsia and normotensive women were assessed using independent t-test for normal distributed data, and the Mann-Whitney test for non-normally distributed data. Results Mean 8-isoprostane level was significantly higher in women with pre-eclampsia than in normotensive women (62.52 ± 12.19 pg/mL vs 28.64 ± 8.81 pg/mL (p<0.05. Low birth weight was twice as frequent in pre-eclampsia than in normotensives. There was no correlation between 8-isoprostane serum level and neonatal birth weight in pre-eclampsia. Conclusion The level of 8-isoprostane was higher in pre-eclampsia than in normotensives. It is recommended to conduct further studies to determine whether 8-isoprostane may be used as a predictive marker of pre-eclampsia.

Very large area multiwire spectroscopic proportional counters

International Nuclear Information System (INIS)

Ubertini, P.; Bazzano, A.; Boccaccini, L.; Mastropietro, M.; La Padula, C.D.; Patriarca, R.; Polcaro, V.F.

1981-01-01

As a result of a five year development program, a final prototype of a Very Large Area Spectroscopic Proportional Counter (VLASPC), to be employed in space borne payloads, was produced at the Istituto di Astrofisica Spaziale, Frascati. The instrument is the last version of a new generation of Multiwire Spectroscopic Proportional Counters (MWSPC) succesfully employed in many balloon borne flights, devoted to hard X-ray astronomy. The sensitive area of this standard unit is 2700 cm 2 with an efficiency higher than 10% in the range 15-180 keV (80% at 60 keV). The low cost and weight make this new type of VLASPC competitive with Nal arrays, phoswich and GSPC detectors in terms of achievable scientific results. (orig.)

Very large area multiwire spectroscopic proportional counters

Energy Technology Data Exchange (ETDEWEB)

Ubertini, P.; Bazzano, A.; Boccaccini, L.; Mastropietro, M.; La Padula, C.D.; Patriarca, R.; Polcaro, V.F. (Istituto di Astrofisica Spaziale, Frascati (Italy))

1981-07-01

As a result of a five year development program, a final prototype of a Very Large Area Spectroscopic Proportional Counter (VLASPC), to be employed in space borne payloads, was produced at the Istituto di Astrofisica Spaziale, Frascati. The instrument is the last version of a new generation of Multiwire Spectroscopic Proportional Counters (MWSPC) successfully employed in many balloon borne flights, devoted to hard X-ray astronomy. The sensitive area of this standard unit is 2700 cm/sup 2/ with an efficiency higher than 10% in the range 15-180 keV (80% at 60 keV). The low cost and weight make this new type of VLASPC competitive with Nal arrays, phoswich and GSPC detectors in terms of achievable scientific results.

Pre-metastatic niches

DEFF Research Database (Denmark)

Peinado, Héctor; Zhang, Haiying; Matei, Irina R.

2017-01-01

It is well established that organs of future metastasis are not passive receivers of circulating tumour cells, but are instead selectively and actively modified by the primary tumour before metastatic spread has even occurred. Sowing the 'seeds' of metastasis requires the action of tumour......-secreted factors and tumour-shed extracellular vesicles that enable the 'soil' at distant metastatic sites to encourage the outgrowth of incoming cancer cells. In this Review, we summarize the main processes and new mechanisms involved in the formation of the pre-metastatic niche....

Petroleum source-rock potentials of the cretaceous transgressive-regressive sedimentary sequences of the Cauvery Basin

Science.gov (United States)

Chandra, Kuldeep; Philip, P. C.; Sridharan, P.; Chopra, V. S.; Rao, Brahmaji; Saha, P. K.

The present work is an attempt to contribute to knowledge on the petroleum source-rock potentials of the marine claystones and shales of basins associated with passive continental margins where the source-rock developments are known to have been associated with the anoxic events in the Mesozoic era. Data on three key exploratory wells from three major depressions Ariyallur-Pondicherry, Thanjavur and Nagapattinam of the Cauvery Basin are described and discussed. The average total organic carbon contents of the transgressive Pre-Albian-Cinomanian and Coniacian/Santonian claystones/shales range from 1.44 and 1.16%, respectively. The transgressive/regressive Campanian/Maastrichtian claystones contain average total organic carbon varying from 0.62 to 1.19%. The kerogens in all the studied stratigraphic sequences are classified as type-III with Rock-Eval hydrogen indices varying from 30 to 275. The nearness of land masses to the depositional basin and the mainly clastic sedimentation resulted in accumulation and preservation of dominantly type-III kerogens. The Pre-Albian to Cinomanian sequences of peak transgressive zone deposited in deep marine environments have kerogens with a relatively greater proportion of type-II components with likely greater contribution of planktonic organic matters. The global anoxic event associated with the Albian-Cinomanian marine transgression, like in many other parts of the world, has pervaded the Cauvery Basin and favoured development of good source-rocks with type-III kerogens. The Coniacian-Campanian-Maastrichtian transgressive/regressive phase is identified to be relatively of lesser significance for development of good quality source-rocks.

Simultaneous data pre-processing and SVM classification model selection based on a parallel genetic algorithm applied to spectroscopic data of olive oils.

Science.gov (United States)

Devos, Olivier; Downey, Gerard; Duponchel, Ludovic

2014-04-01

Classification is an important task in chemometrics. For several years now, support vector machines (SVMs) have proven to be powerful for infrared spectral data classification. However such methods require optimisation of parameters in order to control the risk of overfitting and the complexity of the boundary. Furthermore, it is established that the prediction ability of classification models can be improved using pre-processing in order to remove unwanted variance in the spectra. In this paper we propose a new methodology based on genetic algorithm (GA) for the simultaneous optimisation of SVM parameters and pre-processing (GENOPT-SVM). The method has been tested for the discrimination of the geographical origin of Italian olive oil (Ligurian and non-Ligurian) on the basis of near infrared (NIR) or mid infrared (FTIR) spectra. Different classification models (PLS-DA, SVM with mean centre data, GENOPT-SVM) have been tested and statistically compared using McNemar's statistical test. For the two datasets, SVM with optimised pre-processing give models with higher accuracy than the one obtained with PLS-DA on pre-processed data. In the case of the NIR dataset, most of this accuracy improvement (86.3% compared with 82.8% for PLS-DA) occurred using only a single pre-processing step. For the FTIR dataset, three optimised pre-processing steps are required to obtain SVM model with significant accuracy improvement (82.2%) compared to the one obtained with PLS-DA (78.6%). Furthermore, this study demonstrates that even SVM models have to be developed on the basis of well-corrected spectral data in order to obtain higher classification rates. Copyright © 2013 Elsevier Ltd. All rights reserved.

A spectroscopic census in young stellar regions: the σ Orionis cluster

Energy Technology Data Exchange (ETDEWEB)

Hernández, Jesús; Perez, Alice; Hernan, Ramírez [Centro de Investigaciones de Astronomía, Apdo. Postal 264, Mérida 5101-A (Venezuela, Bolivarian Republic of); Calvet, Nuria; Hartmann, Lee [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Briceño, Cesar [Cerro Tololo Interamerican Observatory, Casilla 603, La Serena (Chile); Olguin, Lorenzo [Depto. de Investigación en Física, Universidad de Sonora, Sonora (Mexico); Contreras, Maria E. [Instituto de Astronomía, Universidad Nacional Autónoma de México, Ensenada, BC (Mexico); Allen, Lori [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Espaillat, Catherine, E-mail: hernandj@cida.ve [Department of Astronomy, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States)

2014-10-10

We present a spectroscopic survey of the stellar population of the σ Orionis cluster. We have obtained spectral types for 340 stars. Spectroscopic data for spectral typing come from several spectrographs with similar spectroscopic coverage and resolution. More than half of the stars in our sample are members confirmed by the presence of lithium in absorption, strong Hα in emission or weak gravity-sensitive features. In addition, we have obtained high-resolution (R ∼ 34,000) spectra in the Hα region for 169 stars in the region. Radial velocities were calculated from this data set. The radial velocity distribution for members of the cluster is in agreement with previous work. Analysis of the profile of the Hα line and infrared observations reveals two binary systems or fast rotators that mimic the Hα width expected in stars with accretion disks. On the other hand, there are stars with optically thick disks and narrow Hα profiles not expected in stars with accretion disks. This contribution constitutes the largest homogeneous spectroscopic data set of the σ Orionis cluster to date.

THE CLUSTERING OF GALAXIES IN THE SDSS-III BARYON OSCILLATION SPECTROSCOPIC SURVEY: LUMINOSITY AND COLOR DEPENDENCE AND REDSHIFT EVOLUTION

Energy Technology Data Exchange (ETDEWEB)

Guo Hong; Zehavi, Idit [Department of Astronomy, Case Western Reserve University, OH 44106 (United States); Zheng Zheng [Department of Physics and Astronomy, University of Utah, UT 84112 (United States); Weinberg, David H. [Department of Astronomy and CCAPP, Ohio State University, Columbus, OH 43210 (United States); Berlind, Andreas A. [Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States); Blanton, Michael [Center for Cosmology and Particle Physics, New York University, New York, NY 10003 (United States); Chen Yanmei [Department of Astronomy, Nanjing University, Nanjing 210093 (China); Eisenstein, Daniel J.; McBride, Cameron K. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Ho, Shirley; Ross, Nicholas P. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Kazin, Eyal [Center for Astrophysics and Supercomputing, Swinburne University of Technology, P.O. Box 218, Hawthorn, Victoria 3122 (Australia); Manera, Marc; Maraston, Claudia; Percival, Will J.; Ross, Ashley J.; Samushia, Lado [Institute of Cosmology and Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth, PO1 3FX (United Kingdom); Nuza, Sebastian E. [Leibniz-Institut fuer Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany); Padmanabhan, Nikhil; Parejko, John K. [Department of Physics, Yale University, 260 Whitney Ave, New Haven, CT 06520 (United States); and others

2013-04-20

We measure the luminosity and color dependence and the redshift evolution of galaxy clustering in the Sloan Digital Sky Survey-III Baryon Oscillation Spectroscopic Survey Ninth Data Release. We focus on the projected two-point correlation function (2PCF) of subsets of its CMASS sample, which includes about 260,000 galaxies over {approx}3300 deg{sup 2} in the redshift range 0.43 < z < 0.7. To minimize the selection effect on galaxy clustering, we construct well-defined luminosity and color subsamples by carefully accounting for the CMASS galaxy selection cuts. The 2PCF of the whole CMASS sample, if approximated by a power-law, has a correlation length of r{sub 0} = 7.93 {+-} 0.06 h {sup -1} Mpc and an index of {gamma} = 1.85 {+-} 0.01. Clear dependences on galaxy luminosity and color are found for the projected 2PCF in all redshift bins, with more luminous and redder galaxies generally exhibiting stronger clustering and steeper 2PCF. The color dependence is also clearly seen for galaxies within the red sequence, consistent with the behavior of SDSS-II main sample galaxies at lower redshifts. At a given luminosity (k + e corrected), no significant evolution of the projected 2PCFs with redshift is detected for red sequence galaxies. We also construct galaxy samples of fixed number density at different redshifts, using redshift-dependent magnitude thresholds. The clustering of these galaxies in the CMASS redshift range is found to be consistent with that predicted by passive evolution. Our measurements of the luminosity and color dependence and redshift evolution of galaxy clustering will allow for detailed modeling of the relation between galaxies and dark matter halos and new constraints on galaxy formation and evolution.

Er2O3 coating by reactive magnetron sputtering: Effect of oxygen supply and erbium pre-layer deposition

Directory of Open Access Journals (Sweden)

P.A. Rayjada

2016-12-01

The film grows in mixed phase of cubic and monoclinic structures when erbium metal pre-layer is deposited on the P91 steel substrate and in pure monoclinic phase in absence of the pre-layer. Post annealing seems to partially convert monoclinic into cubic phase in the mixed phase coating. Better crystallization and slightly more surface roughness is observed in the sample processed with higher oxygen to argon ratio. DC resistivity is found in 1015Ω*cm range and it is marginally more in the sample processed with more oxygen. The spectroscopic ellipsometry on these films to obtain optical dielectric properties gives encouraging results in terms of close match of the thickness and roughness values with those obtained from SEM and AFM respectively. Systematic study of optical dielectric property suggests a trend consistent with DC resistivity.

QUANTIFYING THE BIASES OF SPECTROSCOPICALLY SELECTED GRAVITATIONAL LENSES

International Nuclear Information System (INIS)

Arneson, Ryan A.; Brownstein, Joel R.; Bolton, Adam S.

2012-01-01

Spectroscopic selection has been the most productive technique for the selection of galaxy-scale strong gravitational lens systems with known redshifts. Statistically significant samples of strong lenses provide a powerful method for measuring the mass-density parameters of the lensing population, but results can only be generalized to the parent population if the lensing selection biases are sufficiently understood. We perform controlled Monte Carlo simulations of spectroscopic lens surveys in order to quantify the bias of lenses relative to parent galaxies in velocity dispersion, mass axis ratio, and mass-density profile. For parameters typical of the SLACS and BELLS surveys, we find (1) no significant mass axis ratio detection bias of lenses relative to parent galaxies; (2) a very small detection bias toward shallow mass-density profiles, which is likely negligible compared to other sources of uncertainty in this parameter; (3) a detection bias toward smaller Einstein radius for systems drawn from parent populations with group- and cluster-scale lensing masses; and (4) a lens-modeling bias toward larger velocity dispersions for systems drawn from parent samples with sub-arcsecond mean Einstein radii. This last finding indicates that the incorporation of velocity-dispersion upper limits of non-lenses is an important ingredient for unbiased analyses of spectroscopically selected lens samples. In general, we find that the completeness of spectroscopic lens surveys in the plane of Einstein radius and mass-density profile power-law index is quite uniform, up to a sharp drop in the region of large Einstein radius and steep mass-density profile, and hence that such surveys are ideally suited to the study of massive field galaxies.

Absolute dimensions and masses of eclipsing binaries. V. IQ Persei

International Nuclear Information System (INIS)

Lacy, C.H.; Frueh, M.L.; McDonald Observatory, Austin)

1985-01-01

New photometric and spectroscopic observations of the 1.7 day eclipsing binary IQ Persei (B8 + A6) have been analyzed to yield very accurate fundamental properties of the system. Reticon spectroscopic observations obtained at McDonald Observatory were used to determine accurate radial velocities of both stars in this slightly eccentric large light-ratio binary. A new set of VR light curves obtained at McDonald Observatory were analyzed by synthesis techniques, and previously published UBV light curves were reanalyzed to yield accurate photometric orbits. Orbital parameters derived from both sets of photometric observations are in excellent agreement. The absolute dimensions, masses, luminosities, and apsidal motion period (140 yr) derived from these observations agree well with the predictions of theoretical stellar evolution models. The A6 secondary is still very close to the zero-age main sequence. The B8 primary is about one-third of the way through its main-sequence evolution. 27 references

Pre-hospital and hospital delay in patients with non-ST elevation acute coronary syndromes in tertiary care

Directory of Open Access Journals (Sweden)

G.S. Youssef

2017-09-01

Conclusion: Pre-hospital delay was mainly patient-related. Hospital delay was mainly related to healthcare resources. Governmental measures to promote ambulance emergency services may reduce the pre-hospital delay, while improving the utilization of healthcare resources may reduce hospital delay.

Technical report for fabrication and performance test of electrochemical/spectroscopic measurement system

International Nuclear Information System (INIS)

Park, Yong Joon; Cho, Young Hwan; Bae, Sang Eun; Im, Hee Jung; Song, Kyu Seok

2010-01-01

Development of evaluation technology of electrochemical reactions is very essential to understand chemical behavior of actinides and lanthanides in molten salt media in relation to the development of Pyrochemical process. The on-line electrochemical/spectroscopic measurement system is to produce electrochemical parameters and thermodynamic parameters of actinides and lanthanides in molten salts by using spectroscopic techniques such as UV-VIS absorption as well as electrochemical in-situ measurement techniques. The on-line electrochemical/spectroscopic measurement system can be applied to understand the chemical reactions and oxidation states of actinides and lanthanides in molten salts eventually for the Pyrochemical process

Spectroscopic and physical parameters of Galactic O-type stars. III. Mass discrepancy and rotational mixing

Science.gov (United States)

Markova, N.; Puls, J.; Langer, N.

2018-05-01

Context. Massive stars play a key role in the evolution of galaxies and our Universe. Aims: Our goal is to compare observed and predicted properties of single Galactic O stars to identify and constrain uncertain physical parameters and processes in stellar evolution and atmosphere models. Methods: We used a sample of 53 objects of all luminosity classes and with spectral types from O3 to O9.7. For 30 of these, we determined the main photospheric and wind parameters, including projected rotational rates accounting for macroturbulence, and He and N surface abundances, using optical spectroscopy and applying the model atmosphere code FASTWIND. For the remaining objects, similar data from the literature, based on analyses by means of the CMFGEN code, were used instead. The properties of our sample were then compared to published predictions based on two grids of single massive star evolution models that include rotationally induced mixing. Results: Any of the considered model grids face problem in simultaneously reproducing the stellar masses, equatorial gravities, surface abundances, and rotation rates of our sample stars. The spectroscopic masses derived for objects below 30 M⊙ tend to be smaller than the evolutionary ones, no matter which of the two grids have been used as a reference. While this result may indicate the need to improve the model atmosphere calculations (e.g. regarding the treatment of turbulent pressure), our analysis shows that the established mass problem cannot be fully explained in terms of inaccurate parameters obtained by quantitative spectroscopy or inadequate model values of Vrot on the zero age main sequence. Within each luminosity class, we find a close correlation of N surface abundance and luminosity, and a stronger N enrichment in more massive and evolved O stars. Additionally, we also find a correlation of the surface nitrogen and helium abundances. The large number of nitrogen-enriched stars above 30 M⊙ argues for rotationally

GENERACIÓN DEL DIAGRAMA DE SECUENCIAS DE UML 2.1.1 DESDE ESQUEMAS PRECONCEPTUALES GENERATION OF UML 2.1.1 SEQUENCE DIAGRAM FROM PRE-CONCEPTUAL SCHEMES

Directory of Open Access Journals (Sweden)

Carlos Mario Zapata

2008-12-01

the sequence diagram (including combined fragments from pre-conceptual schemas. These heuristic rules are implemented in the AToM³ tool and applied in a case study.

Exploring the Interactions of the Dietary Plant Flavonoids Fisetin and Naringenin with G-Quadruplex and Duplex DNA, Showing Contrasting Binding Behavior: Spectroscopic and Molecular Modeling Approaches.

Science.gov (United States)

Bhattacharjee, Snehasish; Chakraborty, Sandipan; Sengupta, Pradeep K; Bhowmik, Sudipta

2016-09-01

Guanine-rich sequences have the propensity to fold into a four-stranded DNA structure known as a G-quadruplex (G4). G4 forming sequences are abundant in the promoter region of several oncogenes and become a key target for anticancer drug binding. Here we have studied the interactions of two structurally similar dietary plant flavonoids fisetin and naringenin with G4 as well as double stranded (duplex) DNA by using different spectroscopic and modeling techniques. Our study demonstrates the differential binding ability of the two flavonoids with G4 and duplex DNA. Fisetin more strongly interacts with parallel G4 structure than duplex DNA, whereas naringenin shows stronger binding affinity to duplex rather than G4 DNA. Molecular docking results also corroborate our spectroscopic results, and it was found that both of the ligands are stacked externally in the G4 DNA structure. C-ring planarity of the flavonoid structure appears to be a crucial factor for preferential G4 DNA recognition of flavonoids. The goal of this study is to explore the critical effects of small differences in the structure of closely similar chemical classes of such small molecules (flavonoids) which lead to the contrasting binding properties with the two different forms of DNA. The resulting insights may be expected to facilitate the designing of the highly selective G4 DNA binders based on flavonoid scaffolds.

Trade practices are main factors involved in the transmission of viral haemorrhagic septicaemia

DEFF Research Database (Denmark)

Reichert, M.; Matras, M.; Skall, Helle Frank

2013-01-01

subgroups. The main source of outbreaks in European rainbow trout farming is sublineage Ia isolates. Recently, this group of isolates has been further subdivided in to two subclades of which the Ia-2 consists of isolates occurring mainly in Continental Europe outside of Denmark. In this study, we sequenced...... the full-length G-gene sequences of 24 VHSV isolates that caused VHS outbreaks in Polish trout farms between 2005 and 2009. All these isolates were identified as genotype Ia-2; they divided however into two genetically distinct subgroups, that we name Pol I and Pol II. The Pol I isolates mainly caused...... cause of virus transmission appears to be movement of fish. At least in Polish circumstances trading practices appear to have significant impact on spreading of VHSV infection....

The HITRAN2016 molecular spectroscopic database

Energy Technology Data Exchange (ETDEWEB)

Gordon, I. E.; Rothman, L. S.; Hill, C.; Kochanov, R. V.; Tan, Y.; Bernath, P. F.; Birk, M.; Boudon, V.; Campargue, A.; Chance, K. V.; Drouin, B. J.; Flaud, J. -M.; Gamache, R. R.; Hodges, J. T.; Jacquemart, D.; Perevalov, V. I.; Perrin, A.; Shine, K. P.; Smith, M. -A. H.; Tennyson, J.; Toon, G. C.; Tran, H.; Tyuterev, V. G.; Barbe, A.; Császár, A. G.; Devi, V. M.; Furtenbacher, T.; Harrison, J. J.; Hartmann, J. -M.; Jolly, A.; Johnson, T. J.; Karman, T.; Kleiner, I.; Kyuberis, A. A.; Loos, J.; Lyulin, O. M.; Massie, S. T.; Mikhailenko, S. N.; Moazzen-Ahmadi, N.; Müller, H. S. P.; Naumenko, O. V.; Nikitin, A. V.; Polyansky, O. L.; Rey, M.; Rotger, M.; Sharpe, S. W.; Sung, K.; Starikova, E.; Tashkun, S. A.; Auwera, J. Vander; Wagner, G.; Wilzewski, J.; Wcisło, P.; Yu, S.; Zak, E. J.

2017-12-01

This paper describes the contents of the 2016 edition of the HITRAN molecular spectroscopic compilation. The new edition replaces the previous HITRAN edition of 2012 and its updates during the intervening years. The HITRAN molecular absorption compilation is comprised of five major components: the traditional line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, infrared absorption cross-sections for molecules not yet amenable to representation in a line-by-line form, collision-induced absorption data, aerosol indices of refraction, and general tables such as partition sums that apply globally to the data. The new HITRAN is greatly extended in terms of accuracy, spectral coverage, additional absorption phenomena, added line-shape formalisms, and validity. Moreover, molecules, isotopologues, and perturbing gases have been added that address the issues of atmospheres beyond the Earth. Of considerable note, experimental IR cross-sections for almost 200 additional significant molecules have been added to the database.

Sequence of tenses: playing with possibilities

Directory of Open Access Journals (Sweden)

Bohdan Ulašin

2012-12-01

Full Text Available The aim of this article is to analyse the sequence of tenses in Spanish, a phenomenon typical of the Romance languages. Our purpose is to systematize and formulate the rules of use by means of examples with graphical representations. We focus on such cases of use of the sequence of tenses where it is possible to apply a “double-access interpretation”, i. e. which allows the possibility of choosing between reference points: with the actual time (the moment of speech or with the main clause. This double interpretation is to be found in all three types of time relationships: simultaneousness, priority and posteriority. Some pairs differ semantically; others are used according to the preferences of the speaker with no change of meaning. Most examples are subordinate noun clauses, nonetheless we included examples of other types of clauses as well (e.g. relative, reason clauses. We also analyze the problem of the sequence of tenses where the main verb is in the conditional tense.

Theoretical studies on CH+ ion molecule using configuration interaction method and its spectroscopic properties

International Nuclear Information System (INIS)

Machado, F.B.C.

1985-01-01

The use of the configuration (CI) method for the calculation of very accurate potential energy curves and dipole moment functions, and then their use in the comprehension of spectroscopic properties of diatomic molecules is presented. The spectroscopic properties of CH + and CD + such as: vibrational levels, spectroscopic constants, averaged dipole moments for all vibrational levels, radiative transition probabilities for emission and absorption, and radiative lifetimes are verificated. (M.J.C.) [pt

Automated prescription of oblique brain 3D magnetic resonance spectroscopic imaging.

Science.gov (United States)