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Sample records for ap star beta

  1. The radius and effective temperature of the binary Ap star beta CrB from CHARA/FLUOR and VLT/NACO observations

    CERN Document Server

    Bruntt, H; Merand, A; Brandao, I M; Bedding, T R; Brummelaar, T A ten; Foresto, V Coude du; Cunha, M S; Farrington, C; Goldfinger, P J; Kiss, L L; McAlister, H A; Ridgway, S T; Sturmann, J; Sturmann, L; Turner, N; Tuthill, P G

    2009-01-01

    The prospects for using asteroseismology of rapidly oscillating Ap (roAp) stars are hampered by the large uncertainty in fundamental stellar parameters. Results in the literature for the effective temperature (Teff) often span a range of 1000 K. Our goal is to reduce systematic errors and improve the Teff calibration of Ap stars based on new interferometric measurements. We obtained long-baseline interferometric observations of beta CrB using the CHARA/FLUOR instrument. To disentangle the flux contributions of the two components of this binary star, we obtained VLT/NACO adaptive optics images. We determined limb darkened angular diameters of 0.699+-0.017 mas for beta CrB A (from interferometry) and 0.415+-0.017 mas for beta CrB B (from surface brightness- color relations), corresponding to radii of 2.63+-0.09 Rsun (3.4 percent uncertainty) and 1.56+-0.07 Rsun (4.5 percent). The combined bolometric flux of the A and B components was determined from satellite UV data, spectrophotometry in the visible and broadb...

  2. Multiplicity of rapidly oscillating Ap stars

    CERN Document Server

    Schoeller, M; Hubrig, S; Kurtz, D W

    2012-01-01

    Rapidly oscillating Ap (roAp) stars have rarely been found in binary or higher order multiple systems. This might have implications for their origin. We intend to study the multiplicity of this type of chemically peculiar stars, looking for visual companions in the range of angular separation between 0.05" and 8". We carried out a survey of 28 roAp stars using diffraction-limited near-infrared imaging with NAOS-CONICA at the VLT. Additionally, we observed three non-oscillating magnetic Ap stars. We detected a total of six companion candidates with low chance projection probabilities. Four of these are new detections, the other two are confirmations. An additional 39 companion candidates are very likely chance projections. We also found one binary system among the non-oscillating magnetic Ap stars. The detected companion candidates have apparent K magnitudes between 6.8 and 19.5 and angular separations ranging from 0.23" to 8.9", corresponding to linear projected separations of 30-2400AU. While our study confi...

  3. AP stars with resolved Zeeman split lines

    Science.gov (United States)

    Mathys, G.

    1990-06-01

    High-resolution, high SNR observations of a sample of sharp-lined A stars and of Ap stars showing resolved Zeeman split lines are presented. The Fe II lines 6147.7 A and 6149.2 A unexpectedly appear to be asymmetric in all stars where they are resolved. The blue component of the 6149.2 line, which is a Zeeman doublet, is deeper and narrower than its red component. For line 6147.7, whose Zeeman pattern does not differ much from a quadruplet, the red components are deeper than the blue ones. It is shown that a partial Paschen-Back effect can account for these properties. The potential implications of this finding for studies of magnetic Ap stars are discussed.

  4. The Dushak–Erekdag Survey of roAp Stars

    Indian Academy of Sciences (India)

    Tatyana Dorokhova; Nikolay Dorokhov

    2005-06-01

    The search of roAp stars at Mt. Dushak–Erekdag Observatory was started in 1992 using the 0.8m Odessa telescope equipped with a two-star high-speed photometer. We have observed more than a dozen stars so far and discovered HD 99563 as roAp star while BD+8087 is suspected to have rapid oscillations. Negative results of our observations for the search of rapid oscillations in four stars in NGC 752 are also discussed.

  5. Kepler observations of rapidly oscillating Ap, δ Scuti and γ Doradus pulsations in Ap stars

    DEFF Research Database (Denmark)

    Balona, Luis A.; Cunha, Margarida S.; Kurtz, Donald W.

    2011-01-01

    Observations of the A5p star KIC 8677585 obtained during the Kepler 10-d commissioning run with 1-min time resolution show that it is a rapidly oscillating Ap (roAp) star with several frequencies with periods near 10 min. In addition, a low frequency at 3.142 d−1 is also clearly present....... Multiperiodic γ Doradus (γ Dor) and δ Scuti (δ Sct) pulsations, never before seen in any Ap star, are present in Kepler observations of at least three other Ap stars. Since γ Dor pulsations are seen in Ap stars, it is likely that the low frequency in KIC 8677585 is also a γ Dor pulsation. The simultaneous...... presence of both γ Dor and roAp pulsations and the unexpected detection of δ Sct and γ Dor pulsations in Ap stars present new opportunities and challenges for the interpretation of these stars. Since it is easy to confuse Am and Ap stars at classification dispersions, the nature of these Ap stars...

  6. Stratification in Ap star atmospheres: Simulations

    Science.gov (United States)

    Cowley, Charles R.; Castelli, Fiorella

    2017-01-01

    It is now well established that the atmospheres of Ap stars can be chemically stratified (cf. Babel, A\\&A 258, 645, 1992; Ryabchikova et al. A\\&A 384, 545, 2002). The most convincing cases have been made with the profiles of very strong lines, such as Ca II K. Weaker line profiles are less obvious indicators. The collective behavior of sets or groups of lines have also been used. For example, if higher abundances are derived for strong lines in an atmosphere with zero microturbulence, one may assume that the absorbing species has been pushed into the higher photospheres. An example are the medium-strong Mn II lines in HgMn stars. In this paper, we probe this assumption by calculating line strengths with various assumed stratification models, and then determining abundances from those lines using an {\\bf unstratified} model with the same Teff and log(g). We use the model from Castelli, Kurucz \\& and Hubrig (A\\&A, 508, 401, 2009) for HR 6000, whose spectrum shows numerous indications of stratification. A variety of stratification models are considered, for example, ones where the majority of an absorbing species is concentrated above (or below) $log(\\tau_{5000}$ = -2.0. Cloud models are also investigated, where a species is concentrated within a range of photospheric depths. Curves of growth are generated in unstratified atmospheres for lines by holding the abundance fixed, and increasing log(gf). Similar curves are made in stratified models, and the ratios of strong to weak linesare compared with and without stratification. The effects of stratification on ionization are also investigated, as well as on the profiles of strong lines. We find, in agreement with previous work, that severe abundance jumps are sometimes required to account for some of the observed peculiarities.

  7. Diffusion and Settling in Ap/Bp Stars

    Energy Technology Data Exchange (ETDEWEB)

    Turcotte, S

    2003-04-09

    Ap/Bp stars are magnetic chemically peculiar early A and late B type stars of the main sequence. They exhibit peculiar surface abundance anomalies that are thought to be the result of gravitational settling and radiative levitation. The physics of diffusion in these stars are reviewed briefly and some model predictions are discussed. While models reproduce some observations reasonably well, more work is needed before the behavior of diffusing elements in a complex magnetic field is fully understood.

  8. Diffusion and Settling in Ap/Bp Stars

    CERN Document Server

    Turcotte, S

    2003-01-01

    Ap/Bp stars are magnetic chemically peculiar early A and late B type stars of the main sequence. They exhibit peculiar surface abundance anomalies that are thought to be the result of gravitational settling and radiative levitation. The physics of diffusion in these stars are reviewed briefly and some model predictions are discussed. While models reproduce some observations reasonably well, more work is needed before the behavior of diffusing elements in a complex magnetic field is fully understood.

  9. Study on the faint star extraction technology with MEMS gyro aided APS star tracker

    Science.gov (United States)

    Xing, Fei; Zhao, Borui; Sun, Ting; Xu, Wei; You, Zheng

    2013-08-01

    Star tracker is the most accurate attitude sensor for satellite. Generally speaking, the higher the accuracy, the fainter the star can be sensed by the star tracker. How to extract the faint star from a star image is becoming a critical technology in dynamic condition for star tracker, especially using the APS (Active Pixels Sensor) detector. A novel APS star tracker with MEMS Gyroscope aided system was proposed in this paper that could extremely improve the detection effect and capability for the faint stars. During the exposure time of star tracker, the trajectory of star projection on the detector maybe occupy more than ten pixels due to the satellite rotation. In this situation, the signal-to-noise ratio will decline sharply, and the traditional star extraction method for faint star will take no effect. As a result, the accuracy of star tracker would decline sharply, even more, couldn't work. Using the MEMS Gyroscope, the track of star projection can be predicated and measured, on the basis of which the deconvolution algorithm could be taken to recover the faint star signal. The accuracy of the star projection centroid could be improved obviously, and the dynamic performance of the star tracker would be improved by a magnitude. Meanwhile, the MEMS gyroscope has not less volume, mass and power consumption, which make it more suitable for the application of APS star tracker.

  10. First Magnetic Doppler Images of a roAp star

    Science.gov (United States)

    Lüftinger, T.; Kochukhov, O.; Ryabchikova, T.; Weiss, W. W.; Ilyin, I.

    2007-06-01

    We present the first analysis of the magnetic field geometry and elemental abundance distributions on the surface of a rapidly oscillating Ap (roAp) star, using an elaborate magnetic Doppler Imaging (MDI) code (Piskunov et al. 2002, Kochukhov et al. 2002), inv, which allows to reconstruct simultaneously and consistently the magnetic field geometry and abundance distributions on a stellar surface without any a priori assumptions. We analysed Stokes I and V time series obtained with the SOFIN polarimeter and recovered the magnetic field and surface abundance structures of Fe and Nd (among others). These two elements are found to be anticorrelated.

  11. Abnormal lithium abundance in several Ap-Bp stars

    CERN Document Server

    Shavrina, A; Drake, N A; Kudryavtsev, D O; Gopka, V F; Yushchenko, V A; Yushchenko, A V

    2013-01-01

    Using observations of rapidly rotating roAp star HD 12098, obtained with 6m telescope of SAO RAS in 2005-2008 in nine rotational phases (0.001-0.817), and code V. Tsymbal ROTATE we identified 3 lithium spots on the surface of star, one of them coincided with the position of one magnetic pole and two others are located near the other pole, symmetrically with respect to it. Perhaps magnetic field of the star has a more complex structure than the dipole (Shavrina 2008). Lithium abundance in the spots is greater than cosmic one. It can be explained by diffusion of lithium in the presence of a magnetic field or by production of lithium in the reactions of "spallation" on the surface of star near the magnetic poles (see, for example, Goriely 2007). Enhanced lithium abundances was also determined for other two slowly rotating Ap stars HR 465 and HD 965. The analysis is performed using a synthetic spectrum method taking into account magnetic splitting of lines by the SYNTHM code of Khan (2004).

  12. Magnetic AP Stars in the Hertzsprung-Russell Diagram

    Science.gov (United States)

    Hubrig, S.; North, P.; Mathys, G.

    2000-08-01

    The evolutionary state of magnetic Ap stars is rediscussed using the recently released Hipparcos data. The distribution of the magnetic Ap stars of mass below 3 Msolar in the H-R diagram differs from that of the normal stars in the same temperature range at a high level of significance. Magnetic stars are concentrated toward the center of the main-sequence band. This is shown in two forms of the H-R diagram: one where logL is plotted against logTeff and a version more directly tied to the observed quantities, showing the astrometry-based luminosity (Arenou & Luri) against the (B2-G)0 index of Geneva photometry. In particular, it is found that magnetic fields appear only in stars that have already completed at least approximately 30% of their main-sequence lifetime. No clear picture emerges as to the possible evolution of the magnetic field across the main sequence. Hints of some (loose) relations between magnetic field strength and other stellar parameters are found: stars with shorter periods tend to have stronger fields, as do higher temperature and higher mass stars. A marginal trend of the magnetic flux to be lower in more slowly rotating stars may possibly be seen as suggesting a dynamo origin for the field. No correlation between the rotation period and the fraction of the main-sequence lifetime completed is observed, indicating that the slow rotation in these stars must already have been achieved before they became observably magnetic. Based on data from the ESA Hipparcos satellite and on observations collected at the European Southern Observatory (La Silla, Chile; ESO programs Nos. 43.7-004, 44.7-012, 49.7-030, 50.7-067, 51.7-041, 52.7-063, 53.7-028, 54.E-0416, and 55.E-0751), at the Observatoire de Haute-Provence (Saint-Michel l'Observatoire, France), at Kitt Peak National Observatory, and at the Canada-France-Hawaii Telescope.

  13. On the evolution of the magnetic field of Ap star $\\alpha^2$ CVn

    CERN Document Server

    Bychkov, V D; Madej, J; Topilskaya, G P

    2016-01-01

    New high-precision measurements of the longitudinal magnetic field of Ap stars suggest the existence of secular intrinsic variations of the global magnetic field in some stars. We argue that such changes are apparent in the Ap star $\\alpha^2$ CVn in the time scale of $\\sim$ 10 years, which results from the analysis of literature data. Therefore, such an observation implies, that the rate of magnetic field evolution of Ap stars is much higher than was previously thought.

  14. Towards a theory of rapidly oscillating Ap stars

    CERN Document Server

    Gough, Douglas

    2011-01-01

    Peculiar A stars are so named because they exhibit abundance peculiarities in their atmospheres. It is believed that these arise as a result of differentiation of chemical species in large magnetic spots in which convective mixing is inhibited: there might be just two antipodal spots, whose axis is inclined to the axis of rotation. Many of the Ap stars that are rotating slowly also pulsate, with periods substantially shorter than the period of the fundamental radial mode. The pulsations appear to be nonradial, but axisymmetric, with their common axis usually aligned with the axis of the spots. In this lecture I shall first discuss the magnetic suppression of convection in the spots, and then I shall try to explain the pulsation phenomenon, reviewing some of the suggestions that have been made to explain the alignment and the excitation mechanism, and finally raising some issues that need to be addressed.

  15. Pulsation models for the roAp star HD 134214

    CERN Document Server

    Saio, H; Weiss, W W; Matthews, J M; Ryabchikova, T

    2011-01-01

    Precise time-series photometry with the MOST satellite has led to identification of 10 pulsation frequencies in the rapidly oscillating Ap (roAp) star HD 134214. We have fitted the observed frequencies with theoretical frequencies of axisymmetric modes in a grid of stellar models with dipole magnetic fields. We find that, among models with a standard composition of $(X,Z) = (0.70,0.02)$ and with suppressed convection, eigenfrequencies of a $1.65\\,{\\rm M}_\\odot$ model with $\\log T_{\\rm eff} = 3.858$ and a polar magnetic field strength of 4.1kG agree best with the observed frequencies. We identify the observed pulsation frequency with the largest amplitude as a deformed dipole ($\\ell = 1$) mode, and the four next-largest-amplitude frequencies as deformed $\\ell = 2$ modes. These modes have a radial quasi-node in the outermost atmospheric layers ($\\tau \\sim 10^{-3}$). Although the model frequencies agree roughly with observed ones, they are all above the acoustic cut-off frequency for the model atmosphere and hen...

  16. Period change and stellar evolution of $\\beta$ Cephei stars

    CERN Document Server

    Neilson, Hilding R

    2015-01-01

    The $\\beta$ Cephei stars represent an important class of massive star pulsators probing the evolution of B-type stars and the transition from main sequence to hydrogen-shell burning evolution. By understanding $\\beta$ Cep stars, we gain insights into the detailed physics of massive star evolution such as rotational mixing, convective core overshooting, magnetic fields and stellar winds, all of which play important roles. Similarly, modeling their pulsation provides additional information into their interior structures. Furthermore, measurements of the rate of change of pulsation period offer a direct measure of $\\beta$ Cephei stellar evolution. In this work, we compute state-of-the-art stellar evolution models assuming different amounts of initial rotation and convective core overshoot and measure theoretical rates of period change for which we compare to rates previously measured for a sample of $\\beta$ Cephei stars. The results of this comparison are mixed. For three stars, the rates are too small to infer ...

  17. A self consistent chemically stratified atmosphere model for the roAp star 10 Aquilae

    CERN Document Server

    Nesvacil, Nicole; Ryabchikova, Tanya A; Kochukhov, Oleg; Akberov, Artur; Weiss, Werner W

    2012-01-01

    Context: Chemically peculiar A type (Ap) stars are a subgroup of the CP2 stars which exhibit anomalous overabundances of numerous elements, e.g. Fe, Cr, Sr and rare earth elements. The pulsating subgroup of the Ap stars, the roAp stars, present ideal laboratories to observe and model pulsational signatures as well as the interplay of the pulsations with strong magnetic fields and vertical abundance gradients. Aims: Based on high resolution spectroscopic observations and observed stellar energy distributions we construct a self consistent model atmosphere, that accounts for modulations of the temperature-pressure structure caused by vertical abundance gradients, for the roAp star 10 Aquilae (HD 176232). We demonstrate that such an analysis can be used to determine precisely the fundamental atmospheric parameters required for pulsation modelling. Methods: Average abundances were derived for 56 species. For Mg, Si, Ca, Cr, Fe, Co, Sr, Pr, and Nd vertical stratification profiles were empirically derived using the...

  18. Double Star Measurements of Beta Scorpii

    Science.gov (United States)

    Gillette, Sean; Funk, Benjamin; Schlosser, Ruth; Brown, Alana; Cruz, Mallikai; McCarthy, Jeff; Rhoades, Breauna; Spreng, Bill

    2016-10-01

    Eight observers met at the Lewis Center for Educational Research in Apple Valley, California. These observers studied the distance and position angle between ß1 and ß2 of the beta Scorpii star system. They used the drift method to calibrate the telescope-eyepiece, which was a Celestron C8 Schmidt-Cassegrain telescope equipped with an astrometric eyepiece. The star system g Cassiopeia was used to determine the scale constant of 4.6 arcseconds per division mark, using the average of twelve observations made of the star system using the drift method. A separation of 15.4 arcseconds and a position angle of 14.3 was determined using a Bader Planetarium Micro Guide eyepiece with marking similar to a Celestron Micro Guide eyepiece. A large difference was found compared to WDS due in part to a smoky sky, an incoming storm, and the novice level of the team members, who had a difficult time reading the labels on the eyepiece.

  19. Magnetic fields of Ap stars from the full Stokes spectropolarimetric observations

    CERN Document Server

    Rusomarov, N; Piskunov, N

    2013-01-01

    Current knowledge about stellar magnetic fields relies almost entirely on circular polarization observations. Few objects have been observed in all four Stokes parameters. The magnetic Ap star HD 24712 (DO Eri, HR 1217) was recently observed in the Stokes IQUV parameters with the HARPSpol instrument at the 3.6-m ESO telescope as part of our project at investigating Ap stars in all four Stokes parameters. The resulting spectra have dense phase coverage, resolving power > 10^5, and S/N ratio of 300-600. These are the highest quality full Stokes observations obtained for any star other than the Sun. We present preliminary results from magnetic Doppler imaging of HD 24712. This analysis is the first step towards obtaining detailed 3-D maps of magnetic fields and abundance structures for HD 24712 and other Ap stars that we currently observe with HARPSpol.

  20. Calibration of Strömgren-Crawford photometry for Ap-stars compared to Hipparcos results

    Science.gov (United States)

    Vogt, Nikolaus; Paunzen, Ernst; Maitzen, Hans M.

    25 years ago Bidelman and MacConnell (1973) published a list of nearly 800 Ap-stars which they had identified on objective prism plates collected at the Cerro Tololo Interamerican Observatory as kind of a precursor work for the huge Michigan project of two-dimensional spectral classification. This list has been used as basis for 3 different photometric projects carried out at ESO-La Silla with limiting magnitude V = 8.5: 1. uvby photometry by Vogt and Faúndez (1979); 2. δa photometry by Maitzen and Vogt (1983) in the system of Maitzen (1976) demonstrating the very high agreement of photometric Ap-detections with the spectroscopic results of Bidelman and MacConnell; 3. Hβ photometry of 226 objects which were observed at the Danish 50cm telescope on La Silla in 1982. The latter work was intended not only to formally complete Strögren-Crawford data for a significantly large set of chemically peculiar stars (excluding Am and HgMn objects) but also to yield their galactic locations. Reddening corrections mattered only for the hot peculiars. Absolute magnitudes were derived according to the calibrations worked out by Crawford two decades ago for normal main sequence AB stars. The Hipparcos catalogue which appeared in 1997 offers an independent way to check whether these calibrations derived for normal stars do apply also for chemically peculiar stars. Fortunately, we identified Hipparcos parallaxes for two thirds of our sample. We divided our objects according to 3 calibration groups: early (= B type stars), intermediate (A0-A2 type stars), late (other A type stars). First of all we consider normal stars with published β-values in order to compare their photometric absolute magnitudes to those based on the Hipparcos catalogue. The degree of correlation between both quantities is not excellent for the normal B-type stars, but no systematic trend is visible. For the stars around the Balmer maximum (intermediate group) we also do not recognize a significant systematic

  1. The (BETA) Pictoris Phenomenon Among Herbig Ae/Be Stars

    Science.gov (United States)

    Grady, C. A.; Perez, M. R.; Talavera, A.; Bjorkman, K. S.; deWinter, D.; The, P.-S.; Molster, F. J.; vandenAncker, M. E.; Sitko, M. L.; Morrison, N. D.; Beaver, M. L.; McCollum, B.; Castelaz, M. W.

    1996-01-01

    We present a survey of high dispersion UV and optical spectra of Herbig Ae/Be (HAeBe) and related stars. We find accreting, circumstellar gas over the velocity range +100 to +400 km/s, and absorption profiles similar to those seen toward Beta Pic, in 36% of the 33 HAeBe stars with IUE data as well as in 3 non-emission B stars. We also find evidence of accretion in 7 HAeBe stars with optical data only. Line profile variability appears ubiquitous. As a group, the stars with accreting gas signatures have higher v sin i than the stars with outflowing material, and tend to exhibit large amplitude (greater than or equal to 1(sup m)) optical light variations. All of the program stars with polarimetric variations that are anti-correlated with the optical light, previously interpreted as the signature of a dust disk viewed close to equator-on, also show spectral signatures of accreting gas. These data imply that accretion activity in HAeBe stars is preferentially observed when the line of sight transits the circumstellar dust disk. Our data imply that the spectroscopic signatures of accreting circumstellar material seen in Beta Pic are not unique to that object, but instead are consistent with interpretation of Beta Pic as a comparatively young A star with its associated circumstellar disk.

  2. MALDI, AP/MALDI and ESI techniques for the MS detection of amyloid [beta]-peptides

    Science.gov (United States)

    Grasso, Giuseppe; Mineo, Placido; Rizzarelli, Enrico; Spoto, Giuseppe

    2009-04-01

    Amyloid [beta]-peptides (A[beta]s) are involved in several neuropathological conditions such as Alzheimer's disease and considerable experimental evidences have emerged indicating that different proteases play a major role in regulating the accumulation of A[beta]s in the brain. Particularly, insulin-degrading enzyme (IDE) has been shown to degrade A[beta]s at different cleavage sites, but the experimental results reported in the literature and obtained by mass spectrometry methods are somehow fragmentary. The detection of A[beta]s is often complicated by solubility issues, oxidation artifacts and spontaneous aggregation/cleavage and, in order to rationalize the different reported results, we analyzed A[beta]s solutions by three different MS approaches: matrix assisted laser desorption ionization-time of flight (MALDI-TOF), atmospheric pressure (AP) MALDI ion trap and electrospray ionization (ESI) ion trap. Differences in the obtained results are discussed and ESI is chosen as the most suitable MS method for A[beta]s detection. Finally, cleavage sites produced by interaction of A[beta]s with IDE are identified, two of which had never been reported in the literature.

  3. Testing the presence of lithium on the surfaces of cool Ap stars

    Science.gov (United States)

    Nesvacil, N.; Hubrig, S.; Mathys, G.

    2004-12-01

    The possibility of a quite high Li abundance in the Ap stars was first raised by Wallerstein & Merchant (1965). Since then many studies investigated the problem of Li. The more recent observations in the lithium region indicate that in some Ap stars the λ 6708 feature is variable and this variability can be explained by the existence of Li rich spots on the stellar surface. Atomic data for the Ce II λ 6708.099 were released by the D.R.E.A.M. database in 2002. The line was used to identify the prominent suspected Li-feature in post AGB stars and might as well be responsible for the absorption feature in Ap stars. Recent studies have mentioned this possibility, but it has yet to be investigated in more detail. Other physical phenomena, such as the occurrence of a partial Paschen-Back effect in the presence of magnetic fields, as well as possible hyperfine structure splitting of some Rare Earth transitions, must be taken into account to provide correct line identifications in the wavelength region around the Li-doublet at λ 6708. We discuss a possible strategy to clarify the presence of Li in Ap stars.

  4. Some magnetic null lines of astrophysical interest. II. [in magnetic Ap stars

    Science.gov (United States)

    Adelman, S. J.

    1974-01-01

    A list of magnetic null lines from selected spectroscopic analyses is presented for possible use in detailed studies of magnetic Ap stars. The presented data represent an extension of the magnetic null lines whose usefulness Shore and Adelman (1974) have recently demonstrated for the study of the overall physical conditions prevailing in the atmospheres of peculiar A stars and for testing the consequences of the mechanism of selective elemental diffusion.

  5. Rotation and oblique pulsation in Kepler observations of the roAp star KIC 10483436

    DEFF Research Database (Denmark)

    Balona, L. A.; Cunha, M. S.; Gruberbauer, M.

    2011-01-01

    Photometry of KIC 10483436 was obtained continuously with 1-min exposures over a 27-d period from the Kepler satellite. The light curve shows rotational variations from surface spots with a period of 4.303 ± 0.002 d, an amplitude of about 6 mmag and eight pulsation frequencies typical of roAp stars...

  6. Effects of environmental estrogenic chemicals on AP1 mediated transcription with estrogen receptors alpha and beta.

    Science.gov (United States)

    Fujimoto, Nariaki; Honda, Hiroaki; Kitamura, Shigeyuki

    2004-01-01

    There has been much discussion concerning endocrine disrupting chemicals suspected of exerting adverse effects in both wildlife and humans. Since the majority of these compounds are estrogenic, a large number of in vitro tests for estrogenic characteristics have been developed for screening purpose. One reliable and widely used method is the reporter gene assay employing estrogen receptors (ERs) and a reporter gene with a cis-acting estrogen responsive element (ERE). Other elements such as AP1 also mediate estrogenic signals and the manner of response could be quite different from that of ERE. Since this has yet to be explored, the ER mediated AP1 activity in response to a series of environmental estrogens was investigated in comparison with ERE findings. All the compounds exhibited estrogenic properties with ERE-luc and their AP1 responses were quite similar. These was one exception, however, p,p'-DDT (1,1,1,-trichloro-2,2-bis(p-chlorophenyl)ethane) did not exert any AP1-luc activity, while it appeared to be estrogenic at 10(-7) to 10(-5)M with the ERE action. None of the compounds demonstrated ER beta:AP1 activity. These data suggest that significant differences can occur in responses through the two estrogen pathways depending on environmental chemicals.

  7. Magnetic fields of Ap stars from full Stokes vector spectropolarimetric observations

    CERN Document Server

    Rusomarov, N; Piskunov, N

    2013-01-01

    Our current knowledge about the stellar magnetic fields relies almost entirely on the circular polarization observations. Very few objects have been observed so far in all four Stokes parameters. The magnetic Ap star HD24712 (DO Eri, HR1217) was recently observed in the Stokes IQUV parameters with the HARPSpol instrument at the 3.6-m ESO telescope. The resulting spectra have dense rotational phase coverage, resolving power > 10^5, and a S/N ratio of 300-600. These are the highest quality full Stokes observations obtained for any star other than the Sun. Here we present preliminary results of the magnetic Doppler imaging of HD24712 using HARPSpol spectra. This analysis is the first step towards obtaining detailed 3-D maps of magnetic fields abundance structures for HD24712 and in other Ap stars that we currently observe with HARPSpol.

  8. The roAp star $\\alpha$ Circini as seen by BRITE-Constellation

    CERN Document Server

    Weiss, W W; Pigulski, A; Popowicz, A; Huber, D; Kuschnig, R; Moffat, A F J; Matthews, J M; Saio, H; Schwarzenberg-Czerny, A; Grant, C C; Koudelka, O; Lüftinger, T; Rucinski, S M; Wade, G A; Alves, J; Guedel, M; Handler, G; Mochnacki, St; Orleanski, P; Pablo, B; Pamyatnykh, A; Ramiaramanantsoa, T; Rowe, J; Whittaker, G; Zawistowski, T; Zocłonska, E; Zwintz, K

    2016-01-01

    We report on an analysis of high-precision, multi-colour photometric observations of the rapidly-oscillating Ap (roAp) star $\\alpha$ Cir. These observations were obtained with the BRITE-Constellation, which is a coordinated mission of five nanosatellites that collects continuous millimagnitude-precision photometry of dozens of bright stars for up to 180 days at a time in two colours (Johnson B and R). BRITE stands for BRight Target Explorer. The object $\\alpha$ Cir is the brightest roAp star and an ideal target for such investigations, facilitating the determination of oscillation frequencies with high resolution. This star is bright enough for complementary interferometry and time-resolved spectroscopy. Four BRITE satellites observed $\\alpha$ Cir for 146 d or 33 rotational cycles. Phasing the photometry according to the 4.4790 d rotational period reveals qualitatively different light variations in the two photometric bands. The phased red-band photometry is in good agreement with previously-published WIRE da...

  9. Search of X-ray emission from roAp stars: The case of gamma Equulei

    CERN Document Server

    Stelzer, B; Schöller, M; Hubrig, S; Cowley, C

    2011-01-01

    The detection of X-ray emission from Ap stars can be an indicator for the presence of magnetic activity and dynamo action, provided different origins for the emission, such as wind shocks and close late-type companions, can be excluded. Here we report on results for gamma Equu, the only roAp star for which an X-ray detection is reported in ROSAT catalogs. We use high resolution imaging in X-rays with Chandra and in the near-infrared with NACO/VLT that allow us to spatially resolve companions down to ~1" and ~0.06" separations, respectively. The bulk of the X-ray emission is associated with a companion of gamma Equu identified in our NACO image. Assuming coevality with the primary roAp star (~900 Myr), the available photometry for the companion points at a K-type star with ~0.6 M_sun. Its X-ray properties are in agreement with the predictions for its age and mass. An excess of photons with respect to the expected background and contribution from the nearby companion is observed near the optical position of gam...

  10. X-rays from magnetic intermediate mass Ap/Bp stars

    Science.gov (United States)

    Robrade, Jan

    2016-09-01

    The X-ray emission of magnetic intermediate mass Ap/Bp stars is reviewed and put into context of intrinsic as well as extrinsic hypotheses for its origin. New X-ray observations of Ap/Bp stars are presented and combined with an updated analysis of the available datasets, providing the largest sample of its type that is currently available. In the studied stars the X-ray detections are found predominantly among the more massive, hotter and more luminous targets. Their X-ray properties are quite diverse and beside strong soft X-ray emission significant magnetic activity is frequently present. While a connection between more powerful winds and brighter X-ray emission is expected in intrinsic models, the scatter in X-ray luminosity at given bolometric luminosity is so far unexplained and several observational features like X-ray light curves and flaring, luminosity distributions and spectral properties are often similar to those of low-mass stars. It remains to be seen if these features can be fully reproduced by magnetospheres of intermediate mass stars. The article discusses implications for magnetically confined wind-shock models (MCWS) and stellar magnetospheres under the assumption that the intrinsic model is applicable, but also examines the role of possible companions. Further, related magnetospheric phenomena are presented and an outlook on future perspectives is given.

  11. Abundance distributions over the surfaces of magnetic ApBp stars: theoretical predictions

    CERN Document Server

    Alecian, G

    2015-01-01

    Recently published empirical abundance maps, obtained through (Zeeman) Doppler mapping (ZDM), do not currently agree with the abundance structures predicted by means of numerical models of atomic diffusion in magnetic atmospheres of ApBp stars. In a first step towards the resolution of these discrepancies, we present a state of the art grid of equilibrium abundance stratifications in the atmosphere of a magnetic Ap star with T_eff = 10000 K and log g = 4.0. A description of the behaviour of 16 chemical elements including predictions concerning the over- and/or under-abundances over the stellar surface is followed by a discussion of the possible influence of presently neglected physical processes.

  12. Indirect imaging of nonradial pulsations in a rapidly oscillating Ap star

    CERN Document Server

    Kochukhov, O P

    2004-01-01

    Many types of stars show periodic variations of radius and brightness, which are commonly referred to as `stellar pulsations'. Observed pulsational characteristics are determined by fundamental stellar parameters. Consequently, investigations of stellar pulsations provide a unique opportunity to verify and refine our understanding of the evolution and internal structure of stars. However, a key boundary condition for this analysis -- precise information about the geometry of pulsations in the outer stellar envelopes -- has been notoriously difficult to secure. Here we demonstrate that it is possible to solve this problem by constructing an `image' of the pulsation velocity field from time series observations of stellar spectra. This technique is applied to study the geometry of nonradial pulsations in a prototype magnetic oscillating (roAp) star HR 3831. Our velocity map directly demonstrates an alignment of pulsations with the axis of the global magnetic field and reveals a significant magnetically induced d...

  13. Magnetic Doppler imaging of the roAp star HD 24712

    CERN Document Server

    Lüftinger, T; Ryabchikova, T; Piskunov, N; Weiss, W W; Ilyin, I

    2009-01-01

    We present the first magnetic Doppler images of a rapidly oscillating Ap (roAp) star. We deduce information about magnetic field geometry and abundance distributions of a number of chemical elements on the surface of the hitherto best studied roAp star, HD 24712, using the magnetic Doppler imaging (MDI) code, INVERS10, which allows us to reconstruct simultaneously and consistently the magnetic field geometry and elemental abundance distributions on a stellar surface. For this purpose we analyse time series spectra obtained in Stokes I and V parameters with the SOFIN polarimeter at the Nordic Optical Telescope and recover surface abundance structures of sixteen different chemical elements, respectively ions, including Mg, Ca, Sc, Ti, Cr, Fe, Co, Ni, Y, La, Ce, Pr, Nd, Gd, Tb, and Dy. For the rare earth elements (REE) Pr and Nd separate maps were obtained using lines of the first and the second ionization stage. We find and confirm a clear dipolar structure of the surface magnetic field and an unexpected correl...

  14. Biodegradable star polymers functionalized with beta-cyclodextrin inclusion complexes.

    Science.gov (United States)

    Setijadi, Eki; Tao, Lei; Liu, Jingquan; Jia, Zhongfan; Boyer, Cyrille; Davis, Thomas P

    2009-09-14

    Three-armed biodegradable star polymers made from polystyrene (polySt) and poly (polyethylene glycol) acrylate (polyPEG-A) were synthesized via a "core first" methodology using a trifunctional RAFT agent, created by attaching RAFT agents to a core via their R-groups. The resultant three-armed polymeric structures were well-defined, with polydispersity indices less than 1.2. Upon aminolysis and further reaction with dithiodipyridine (DTDP), these three-armed polymers could be tailored with sulfhydryl and pyridyldisulfide (PDS) end functionalities, available for further reaction with any free-sulfhydryl group containing precursors to form disulfide linkages. Nuclear magnetic resonance (NMR) confirmed that more than 98% of the polymer arms retained integral trithiocarbonate active sites after polymerization. Intradisulfide linkages between the core and the arms conferred biodegradability on the star architectures. Subsequently, the arm-termini were attached to cholesterol also via disulfide linkages. The cholesterol terminated arms were then used to form supramolecular structures via inclusion complex formation with beta-cyclodextrin (beta-CD). The star architectures were found to degrade rapidly on treatment with DL-dithiothereitol (DTT). The star polymers and supramolecular structures were characterized using gel permation chromatography (GPC), static light scattering (SLS), 2D NMR, and fluorescence spectroscopy.

  15. KIC 7582608: a new Kepler roAp star with frequency variability

    Directory of Open Access Journals (Sweden)

    Holdsworth D.L.

    2015-01-01

    Full Text Available We analyse the fifth roAp star reported in the Kepler field, KIC 7582608, discovered with the SuperWASP project. The object shows a high frequency pulsation at 181.7324d−1 (P = 7.9 min with an amplitude of 1.45 mmag, and low frequency rotational modulation corresponding to a period of 20.4339 d. Spectral analysis confirms the Ap nature of the target, with characteristic lines of rare earth elements present. From our spectral observations we derive a lower limit on the mean magnetic field modulus of 〈B〉 =3.05 ± 0.23 kG. Long Cadence Kepler observations show a frequency quintuplet split by the rotational period of the star, typical for an oblique pulsator. We suggest the star is a quadrupole pulsator with a geometry such that i ~ 66° and β ~ 33°. We detect frequency variations of the pulsation in both the WASP and Kepler data sets on many time scales. Linear, non-adiabatic stability modelling allows us to constrain a region on the HR diagram where the pulsations are unstable, an area consistent with observations.

  16. Time-resolved photometric and spectroscopic analysis of a luminous Ap star HD103498

    CERN Document Server

    Joshi, S; Kochukhov, O; Sachkov, M; Tiwari, S K; Chakradhari, N K; Piskunov, N

    2009-01-01

    We present the results on the photometric and spectroscopic monitoring of a luminous Ap star HD103498. The time-series photometric observations were carried out on 17 nights using three-channel fast photometer attached to the 1.04-m optical telescope at ARIES, Nainital. The photometric data of five nights of year 2007 show clear signature of 15-min periodicity. However, the follow-up observations during 2007--2009 could not repeated any such periodicity. To confirm the photometric light variations, the time-series spectroscopic observations were carried out with the 2.56-m Nordic Optical Telescope (NOT) at La Palma on February 2, 2009. Any radial velocity variations were absent in this data set which is in full agreement with the photometric observations taken near the same night. Model atmosphere and abundance analysis of HD103498 show that the star is evolved from the Main Sequence and its atmospheric abundances are similar to two other evolved Ap stars HD133792 and HD204411: large overabundances of Si, Cr,...

  17. Magnetic field topology and chemical spot distributions in the extreme Ap star HD 75049

    CERN Document Server

    Kochukhov, O; Valenti, J A; Stempels, H C; Snik, F; Rodenhuis, M; Piskunov, N; Makaganiuk, V; Keller, C U; Johns-Krull, C M

    2014-01-01

    Intermediate-mass, magnetic chemically peculiar (Ap) stars provide a unique opportunity to study the topology of stellar magnetic fields in detail and to investigate magnetically driven processes of spot formation. Here we aim to derive the surface magnetic field geometry and chemical abundance distributions for the extraordinary Ap star HD 75049. This object hosts a surface field of ~30 kG, one of the strongest known for any non-degenerate star. We used time-series of high-resolution HARPS intensity and circular polarisation observations. These data were interpreted with the help of magnetic Doppler imaging and model atmospheres incorporating effects of a non-solar chemical composition and a strong magnetic field. We refined the rotational period of HD 75049 to Prot=4.048267+/-0.000036 d. We also derived basic stellar parameters, Teff=10250+/-250 K and logg=4.3+/-0.1. Magnetic Doppler imaging revealed that the field topology of HD 75049 is poloidal and dominated by a dipolar contribution with a peak surface ...

  18. Modelling the incomplete Paschen-Back effect in the spectra of magnetic Ap stars

    OpenAIRE

    Stift, M. J.; Leone, F.; Degl'Innocenti, E. Landi

    2008-01-01

    We present first results of a systematic investigation of the incomplete Paschen-Back effect in magnetic Ap stars. A short overview of the theory is followed by a demonstration of how level splittings and component strengths change with magnetic field strength for some lines of special astrophysical interest. Requirements are set out for a code which allows the calculation of full Stokes spectra in the Paschen-Back regime and the behaviour of Stokes I and V profiles of transitions in the mult...

  19. Observations of roAp stars at the Mt.Dushak-Erekdag station of Odessa Astronomical Observatory

    CERN Document Server

    Dorokhova, T N

    1998-01-01

    Since 1992, observations of roAp stars have been carried out using the dual-channel photometer attached to the 0.8m telescope, which is situated in Central Asia, at the Mt. Dushak-Erekdag station of Odessa Astronomical Observatory. Some results of observations of gamma Equ and of HD 134214 are presented. 5 stars were investigated as roAp candidates. The Fourier spectra of 4 stars did not show any variability in the high-frequency region. The Fourier spectrum of HD 99563 revealed a peak at a frequency f=128.9 c/d and with a semi-amplitude of 3.98 mmag.

  20. HD 24355 observed by the Kepler K2 mission: A rapidly oscillating Ap star pulsating in a distorted quadrupole mode

    CERN Document Server

    Holdsworth, Daniel L; Smalley, Barry; Saio, Hideyuki; Handler, Gerald; Murphy, Simon J; Lehmann, Holger

    2016-01-01

    We present an analysis of the first Kepler K2 mission observations of a rapidly oscillating Ap (roAp) star, HD 24355 ($V=9.65$). The star was discovered in SuperWASP broadband photometry with a frequency of 224.31 d$^{-1}$, (2596.18 $\\mu$Hz; $P = 6.4$ min) and an amplitude of 1.51 mmag, with later spectroscopic analysis of low-resolution spectra showing HD 24355 to be an A5 Vp SrEu star. The high precision K2 data allow us to identify 13 rotationally split sidelobes to the main pulsation frequency of HD 24355. This number of sidelobes combined with an unusual rotational phase variation show this star to be the most distorted quadrupole roAp pulsator yet observed. In modelling this star, we are able to reproduce well the amplitude modulation of the pulsation, and find a close match to the unusual phase variations. We show this star to have a pulsation frequency higher than the critical cut-off frequency. This is currently the only roAp star observed with the Kepler spacecraft in Short Cadence mode that has a p...

  1. The fundamental parameters of the roAp star alpha Circini

    CERN Document Server

    Bruntt, H; Cunha, M; Brandao, I M; Elkin, V G; Kurtz, D W; Davis, J; Bedding, T R; Jacob, A P; Owens, S M; Robertson, J G; Tango, W J; Gameiro, J F; Ireland, M J; Tuthill, P G

    2008-01-01

    We have used the Sydney University Stellar Interferometer (SUSI) to measure the angular diameter of alpha Cir. This is the first detailed interferometric study of a rapidly oscillating A (roAp) star, alpha Cir being the brightest member of its class. We used the new and more accurate Hipparcos parallax to determine the radius to be 1.967+-0.066 Rs. We have constrained the bolometric flux from calibrated spectra to determine an effective temperature of 7420+-170 K. This is the first direct determination of the temperature of an roAp star. Our temperature is at the low end of previous estimates, which span over 1000 K and were based on either photometric indices or spectroscopic methods. In addition, we have analysed two high-quality spectra of alpha Cir, obtained at different rotational phases and we find evidence for the presence of spots. In both spectra we find nearly solar abundances of C, O, Si, Ca and Fe, high abundance of Cr and Mn, while Co, Y, Nd and Eu are overabundant by about 1 dex. The results rep...

  2. Accurate age determinations of several nearby open clusters containing magnetic Ap stars

    CERN Document Server

    Silaj, J

    2014-01-01

    Aims: Our aim is to obtain ages that are as accurate as possible for the seven nearby open clusters alpha Per, Coma Ber, IC 2602, NGC 2232, NGC 2451A, NGC 2516, and NGC 6475, each of which contains at least one magnetic Ap or Bp star. Simultaneously, we test the current calibrations of Te and luminosity for the Ap/Bp star members, and identify clearly blue stragglers in the clusters studied. Methods: We explore the possibility that isochrone fitting in the theoretical Hertzsprung-Russell diagram (i.e. log (L/L&sun;) vs. log Te), rather than in the conventional colour-magnitude diagram, can provide more precise and accurate cluster ages, with well-defined uncertainties. Results: Well-defined ages are found for all the clusters studied. For the nearby clusters studied, the derived ages are not very sensitive to the small uncertainties in distance, reddening, membership, metallicity, or choice of isochrones. Our age determinations are all within the range of previously determined values, but the associated u...

  3. The roAp star α Circinus as seen by BRITE-Constellation

    Science.gov (United States)

    Weiss, W. W.; Fröhlich, H.-E.; Pigulski, A.; Popowicz, A.; Huber, D.; Kuschnig, R.; Moffat, A. F. J.; Matthews, J. M.; Saio, H.; Schwarzenberg-Czerny, A.; Grant, C. C.; Koudelka, O.; Lüftinger, T.; Rucinski, S. M.; Wade, G. A.; Alves, J.; Guedel, M.; Handler, G.; Mochnacki, St.; Orleanski, P.; Pablo, B.; Pamyatnykh, A.; Ramiaramanantsoa, T.; Rowe, J.; Whittaker, G.; Zawistowski, T.; Zocłońska, E.; Zwintz, K.

    2016-04-01

    We report on an analysis of high-precision, multi-colour photometric observations of the rapidly-oscillating Ap (roAp) star α Cir. These observations were obtained with the BRITE-Constellation, which is a coordinated mission of five nanosatellites that collects continuous millimagnitude-precision photometry of dozens of bright stars for up to 180 days at a time in two colours (≈Johnson B and R). BRITE stands for BRight Target Explorer. The object α Cir is the brightest roAp star and an ideal target for such investigations, facilitating the determination of oscillation frequencies with high resolution. This star is bright enough for complementary interferometry and time-resolved spectroscopy. Four BRITE satellites observed α Cir for146 d or 33 rotational cycles. Phasing the photometry according to the 4.4790 d rotational period reveals qualitatively different light variations in the two photometric bands. The phased red-band photometry is in good agreement with previously-published WIRE data, showing a light curve symmetric about phase 0.5 with a strong contribution from the first harmonic. The phased blue-lband data, in contrast, show an essentially sinusoidal variation. We model both light curves with Bayesian Photometric Imaging, which suggests the presence of two large-scale, photometrically bright (relative to the surrounding photosphere) spots. We also examine the high-frequency pulsation spectrum as encoded in the BRITE photometry. Our analysis establishes the stability of the main pulsation frequency over the last ≈20 yr, confirms the presence of frequency f7, which was not detected (or the mode not excited) prior to 2006, and excludes quadrupolar modes for the main pulsation frequency. Based on data collected by the BRITE-Constellation satellite mission, built, launched and operated thanks to support from the Austrian Aeronautics and Space Agency, the University of Vienna, the Canadian Space Agency (CSA), the Foundation for Polish Science

  4. HD 18078: A very slowly rotating Ap star with an unusual magnetic field structure

    Science.gov (United States)

    Mathys, G.; Romanyuk, I. I.; Kudryavtsev, D. O.; Landstreet, J. D.; Pyper, D. M.; Adelman, S. J.

    2016-02-01

    Context. The existence of a significant population of Ap stars with very long rotation periods (up to several hundred years) has progressively emerged over the past two decades. However, only lower limits of the periods are known for most of them because their variations have not yet been observed over a sufficient timebase. Aims: We determine the rotation period of the slowly rotating Ap star HD 18078 and we derive constraints on the geometrical structure of its magnetic field. Methods: We combine measurements of the mean magnetic field modulus obtained from 1990 to 1997 with determinations of the mean longitudinal magnetic field spanning the 1999-2007 time interval to derive an unambiguous value of the rotation period. We show that this value is consistent with photometric variations recorded in the Strömgren uvby photometric system between 1995 and 2004. We fit the variations of the two above-mentioned field moments with a simple model to constrain the magnetic structure. Results: The rotation period of HD 18078 is (1358 ± 12) d. The geometrical structure of its magnetic field is consistent to first order with a colinear multipole model whose axis is offset from the centre of the star. Conclusions: HD 18078 is only the fifth Ap star with a rotation period longer than 1000 d for which the exact value of that period (as opposed to a lower limit) could be determined. The strong anharmonicity of the variations of its mean longitudinal magnetic field and the shift between their extrema and those of the mean magnetic field modulus are exceptional and indicative of a very unusual magnetic structure. Based in part on observations made at Observatoire de Haute Provence (CNRS), France; at Kitt Peak National Observatory, National Optical Astronomy Observatory (NOAO Prop. ID: KP2442; PI: T. Lanz), which is operated by the Association of Universities for Research in Astronomy (AURA) under cooperative agreement with the National Science Foundation; at the Canada

  5. KIC 4768731: a bright long-period roAp star in the Kepler Field

    CERN Document Server

    Smalley, B; Murphy, S J; Lehmann, H; Kurtz, D W; Holdsworth, D L; Cunha, M S; Balona, L A; Briquet, M; Bruntt, H; de Cat, P; Lampens, P; Thygesen, A O; Uytterhoeven, K

    2015-01-01

    We report the identification of 61.45 d^-1 (711.2 mu Hz) oscillations, with amplitudes of 62.6-mu mag, in KIC 4768731 (HD 225914) using Kepler photometry. This relatively bright (V=9.17) chemically peculiar star with spectral type A5 Vp SrCr(Eu) has previously been found to exhibit rotational modulation with a period of 5.21 d. Fourier analysis reveals a simple dipole pulsator with an amplitude that has remained stable over a 4-yr time span, but with a frequency that is variable. Analysis of high-resolution spectra yields stellar parameters of T_eff = 8100 +/- 200 K, log g = 4.0 +/- 0.2, [Fe/H] = +0.31 +/- 0.24 and v sin i = 14.8 +/- 1.6 km/s. Line profile variations caused by rotation are also evident. Lines of Sr, Cr, Eu, Mg and Si are strongest when the star is brightest, while Y and Ba vary in anti-phase with the other elements. The abundances of rare earth elements are only modestly enhanced compared to other roAp stars of similar T_eff and log g. Radial velocities in the literature suggest a significant...

  6. The first evidence for multiple pulsation axes: a new rapidly oscillating Ap star in the Kepler field, KIC 10195926

    DEFF Research Database (Denmark)

    Kurtz, Donald W.; Cunha, Margarida S.; Saio, H.;

    2011-01-01

    model that these two modes cannot have the same axis of pulsation. This is the first time for any pulsating star that evidence has been found for separate pulsation axes for different modes. The two modes are separated in frequency by 55 μHz, which we model as the large separation. The star is an α2 CVn...... to these values that reproduces the rotational variations of the two obliquely pulsating modes with different pulsation axes. The star shows overabundances of the rare earth elements, but these are not as extreme as most other roAp stars. The spectrum is variable with rotation, indicating surface abundance...

  7. Pulsations in the atmosphere of the roAp star HD 24712 II. Theoretical models

    CERN Document Server

    Saio, Hideyuki; Sachkov, Mikhail

    2009-01-01

    We discuss pulsations of the rapidly oscillating Ap (roAp) star HD 24712 (HR 1217) based on nonadiabatic analyses taking into account the effect of dipole magnetic fields. We have found that all the pulsation modes appropriate for HD 24712 are damped; i.e., the kappa-mechanism excitation in the hydrogen ionization layers is not strong enough to excite high-order p-modes with periods consistent with observed ones, all of which are found to be above the acoustic cut-off frequencies of our models. The main (2.721 mHz) and the highest (2.806 mHz) frequencies are matched with modified $l=2$ and $l=3$ modes, respectively. The large frequency separation ($\\approx 68 \\mu$Hz) is reproduced by models which lay within the error box of HD 24712 on the HR diagram. The nearly equally spaced frequencies of HD 24712 indicate the small frequency separation to be as small as $\\approx 0.5\\mu$Hz. However, the small separation derived from theoretical $l=1$ and 2 modes are found to be larger than $\\sim 3\\mu$Hz. The problem of equ...

  8. Atmospheric structure and acoustic cut-off frequency of roAp stars

    CERN Document Server

    Audard, N; Morel, P; Provost, J P; Weiss, W W

    1998-01-01

    Some of the rapidly oscillating (CP2) stars, have frequencies which are larger than the theoretical acoustic cut-off frequency. As the cut-off frequency depends on the T(tau) relation in the atmosphere, we have computed models and adiabatic frequencies for pulsating Ap stars with T(tau) laws based on Kurucz model atmospheres and on Hopf's purely radiative relation. The frequency-dependent treatment of radiative transfer as well as an improved calculation of the radiative pressure in Kurucz model atmospheres increase the theoretical acoustic cut-off frequency by about 200 microHz, which is closer to the observations. For alpha Cir we find models with Kurucz atmospheres which have indeed a cut-off frequency beyond the largest observed frequency and which are well within the Teff - L error box. For HD 24712 only models which are hotter by about 100 K and less luminous by nearly 10% than what is actually the most probable value would have an acoustic cut-off frequency large enough. One may thus speculate that the...

  9. The first evidence for multiple pulsation axes: a new roAp star in the Kepler field, KIC 10195926

    CERN Document Server

    Kurtz, D W; Saio, H; Bigot, L; Balona, L A; Elkin, V G; Shibahashi, H; Brandao, I M; Uytterhoeven, K; Frandsen, S; Frimann, S; Hatzes, A; Lueftinger, T; Gruberbauer, M; Kjeldsen, H; Christensen-Dalsgaard, J; Kawaler, S D

    2011-01-01

    We have discovered a new rapidly oscillating Ap star among the Kepler Mission target stars, KIC 10195926. This star shows two pulsation modes with periods that are amongst the longest known for roAp stars at 17.1 min and 18.1 min, indicating that the star is near the terminal age main sequence. The principal pulsation mode is an oblique dipole mode that shows a rotationally split frequency septuplet that provides information on the geometry of the mode. The secondary mode also appears to be a dipole mode with a rotationally split triplet, but we are able to show within the improved oblique pulsator model that these two modes cannot have the same axis of pulsation. This is the first time for any pulsating star that evidence has been found for separate pulsation axes for different modes. The two modes are separated in frequency by 55 microHz, which we model as the large separation. The star is an alpha^2 CVn spotted magnetic variable that shows a complex rotational light variation with a period of Prot = 5.6845...

  10. The Beta Pictoris Phenomenon in A-Shell Stars: Detection of Accreting Gas

    Science.gov (United States)

    Grady, C. A.; Perez, Mario R.; Talavera, A.; McCollum, B.; Rawley, L. A.; England, M. N.; Schlegel, M.

    1996-01-01

    We present the results of an expanded survey of A-shell stars using IUE high-dispersion spectra and find accreting, circumstellar gas in the line of sight to nine stars, in addition to the previously identified beta Pic, HR 10, and 131 Tau, which can be followed to between +70 and 100 km/s relative to the star. Two of the program stars, HD 88195 and HD 148283, show variable high-velocity gas. Given the small number of IUE spectra for our program stars, detection of high-velocity, accreting gas in 2/3 of the A-shell stars sampled indicates that accretion is an intrinsic part of the A-shell phenomenon and that beta Pic is not unique among main-sequence A stars in exhibiting such activity. Our program stars, as a group, have smaller column densities of high-velocity gas and smaller near-IR excesses compared with beta Pic. These features are consistent with greater central clearing of a remnant debris disk, compared with beta Pic, and suggest that the majority of field A-shell stars are older than beta Pic.

  11. Modelling the incomplete Paschen-Back effect in the spectra of magnetic Ap stars

    CERN Document Server

    Stift, M J; Degl'Innocenti, E Landi

    2008-01-01

    We present first results of a systematic investigation of the incomplete Paschen-Back effect in magnetic Ap stars. A short overview of the theory is followed by a demonstration of how level splittings and component strengths change with magnetic field strength for some lines of special astrophysical interest. Requirements are set out for a code which allows the calculation of full Stokes spectra in the Paschen-Back regime and the behaviour of Stokes I and V profiles of transitions in the multiplet 74 of FeII is discussed in some detail. It is shown that the incomplete Paschen-Back effect can lead to noticeable line shifts which strongly depend on total multiplet strength, magnetic field strength and field direction. Ghost components (which violate the normal selection rule on J) show up in strong magnetic fields but are probably unobservable. Finally it is shown that measurements of the integrated magnetic field modulus $H_s$ are not adversely affected by the Paschen-Back effect, and that there is a potential...

  12. Modelling the incomplete Paschen-Back effect in the spectra of magnetic Ap stars

    Science.gov (United States)

    Stift, M. J.; Leone, F.; Landi Degl'Innocenti, E.

    2008-04-01

    We present preliminary results of a systematic investigation of the incomplete Paschen-Back effect in magnetic Ap stars. A short overview of the theory is followed by a demonstration of how level splittings and component strengths change with magnetic field strength for some lines of special astrophysical interest. Requirements are set out for a code which allows the calculation of full Stokes spectra in the Paschen-Back regime, and the behaviour of Stokes I and V profiles of transitions in the multiplet 74 of FeII is discussed in some detail. It is shown that the incomplete Paschen-Back effect can lead to notable line shifts which strongly depend on total multiplet strength, magnetic field strength and field direction. Ghost components (which violate the normal selection rule on J) show up in strong magnetic fields but are probably unobservable. Finally it is shown that measurements of the integrated magnetic field modulus Hs are not adversely affected by the Paschen-Back effect, and that there is a potential problem in (magnetic) Doppler mapping if lines in the Paschen-Back regime are treated in the Zeeman approximation.

  13. The Solar Neighborhood. XXVI. AP Col: The Closest (8.4 pc) Pre-Main-Sequence Star

    CERN Document Server

    Riedel, Adric R; Henry, Todd J; Melis, Carl; Jao, Wei-Chun; Subasavage, John P; 10.1088/0004-6256/142/4/104

    2011-01-01

    We present the results of a multi-technique investigation of the M4.5Ve flare star AP Col, which we discover to be the nearest pre-main-sequence star. These include astrometric data from the CTIO 0.9m, from which we derive a proper motion of 342.0+/-0.5 mas yr^-1, a trigonometric parallax of 119.21+/-0.98 mas (8.39+/-0.07 pc), and photometry and photometric variability at optical wavelengths. We also provide spectroscopic data, including radial velocity (22.4+/-0.3 km s^-1), lithium Equivalent Width (EW) (0.28+/-0.02 A), H-alpha EW (-6.0 to -35 A), {\\it vsini} (11+/-1 km s^-1), and gravity indicators from the Siding Spring 2.3-m WiFeS, Lick 3-m Hamilton echelle, and Keck-I HIRES echelle spectrographs. The combined observations demonstrate that AP Col is the closer of only two known systems within 10 pc of the Sun younger than 100 Myr. Given its space motion and apparent age of 12-50 Myr, AP Col is likely a member of the recently proposed ~40 Myr old Argus/IC 2391 association.

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

    Science.gov (United States)

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

    1987-01-01

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

  15. The radius and other fundamental parameters of the F9 V star beta Virginis

    CERN Document Server

    North, J R; Robertson, J G; Bedding, T R; Bruntt, H; Ireland, M J; Jacob, A P; Lacour, S; O'Byrne, J W; Owens, S M; Stello, D; Tango, W J; Tuthill, P G

    2008-01-01

    We have used the Sydney University Stellar Interferometer (SUSI) to measure the angular diameter of the F9 V star beta Virginis. After correcting for limb darkening and combining with the revised Hipparcos parallax, we derive a radius of 1.703 +/- 0.022 R_sun (1.3%). We have also calculated the bolometric flux from published measurements which, combined with the angular diameter, implies an effective temperature of 6059 +/- 49 K (0.8%). We also derived the luminosity of beta Vir to be L = 3.51 +/- 0.08 L_sun (2.1%). Solar-like oscillations were measured in this star by Carrier et al. (2005) and using their value for the large frequency separation yields the mean stellar density with an uncertainty of about 2%. Our constraints on the fundamental parameters of beta Vir will be important to test theoretical models of this star and its oscillations.

  16. The WFC3 Mosaic of The Star-Forming Galaxy M51 in Paschen beta

    Science.gov (United States)

    Koda, Jin

    2011-10-01

    We propose WFC3/IR Paschen beta imaging of the entire star-forming disk of M51 in a 10-point mosaic. This proposal is motivated by a new picture of gas evolution in galaxies from our recent observations in carbon-monoxide {CO} emission, namely one driven by galactic dynamics. The Paschen beta and archival ACS/Halpha images will enable correction for extinction throughout the entire M51 disk, and show an unprecedented map of star forming activity across the entire galaxy. By comparing this map with our new CO intensity and velocity maps, we will {1} place star formation in this new context of gas evolution, {2} study the triggering of star formation by correlating the star formation efficiency of individual GMC with global galactic structures {such as observed spiral shear motions and local gas convergence}, and {3} investigate the physics that underlie the Schmidt law by resolving the early-phases of star formation and its environment. The extinction-corrected map of star formation activity will become a reference for future calibration of other tracers of star formation activity and will have an unparalleled archival value.

  17. The Nainital–Cape Survey: A Search for Variability in Ap and Am Stars

    Indian Academy of Sciences (India)

    Santosh Joshi

    2005-06-01

    The ``Nainital–Cape Survey” program for searching photometric variability in chemically peculiar (CP) stars was initiated in 1997 at ARIES, Nainital. We present here the results obtained to date. The Am stars HD 98851, HD 102480, HD 13079 and HD 113878 were discovered to exhibit Scuti type variability. Photometric variability was also discovered in HD 13038, for which the type of peculiarity and variability is not fully explained. The null results of this survey are also presented and discussed.

  18. Weak magnetic fields in Ap/Bp stars: Evidence for a dipole field lower limit and a tentative interpretation of the magnetic dichotomy

    CERN Document Server

    Aurière, M; Silvester, J; Lignières, F; Bagnulo, S; Bale, K; Dintrans, B; Donati, J F; Folsom, C P; Gruberbauer, M; Hoa, A Hui Bon; Jeffers, S; Johnson, N; Landstreet, J D; Lebre, A; Lüftinger, T; Marsden, S; Mouillet, D; Naseri, S; Paletou, F; Petit, P; Power, J; Rincon, F; Strasser, S; Toque, N

    2007-01-01

    We have investigated a sample of 28 well-known spectroscopically-identified magnetic Ap/Bp stars, with weak, poorly-determined or previously undetected magnetic fields, with the aim of exploring the weak part of the magnetic field distribution of Ap/Bp stars. Using the MuSiCoS and NARVAL spectropolarimeters we have obtained 282 LSD Stokes V signatures of our 28 sample stars. All stars were detected, showing clearly that when observed with sufficient precision, all firmly classified Ap/Bp stars show detectable surface magnetic fields. To better characterise the surface magnetic field intensities and geometries of the sample, we have inferred the dipolar field intensity and the magnetic obliquity. The distribution of derived dipole strengths for these stars exhibits a plateau at about 1 kG, falling off to larger and smaller field strengths. Remarkably, in this sample of stars selected for their presumably weak magnetic fields, we find only 2 stars for which the derived dipole strength is weaker than 300 G. We i...

  19. HD 41641: a classical $\\delta$ Sct-type pulsator with chemical signatures of an Ap star

    CERN Document Server

    Escorza, A; Tkachenko, A; Van Reeth, T; Ryabchikova, T; Neiner, C; Poretti, E; Rainer, M; Michel, E; Baglin, A; Aerts, C

    2016-01-01

    Among the known groups of pulsating stars, $\\delta$ Sct stars are one of the least understood. The theoretical models do not predict the oscillation frequencies that observations reveal. Complete asteroseismic studies are necessary to improve these models and better understand the internal structure of these targets. In this paper, we study the $\\delta$ Sct star HD 41641 with the ultimate goal of understanding its oscillation pattern. The target has been simultaneously observed by the CoRoT space telescope and the HARPS high-resolution spectrograph. The photometric data set was analyzed with the software package PERIOD04, while FAMIAS was used to analyze the line profile variations. The method of spectrum synthesis was used for spectroscopically determining the fundamental atmospheric parameters and the individual chemical abundances. A total of 90 different frequencies was identified and analyzed. An unambiguous identification of the azimuthal order of the surface geometry could be provided for the dominant ...

  20. Constraints on model atmospheres from complex asteroseismology of the \\beta Cephei stars

    CERN Document Server

    Szewczuk, Wojciech; Daszyńska-Daszkiewicz, Jadwiga

    2012-01-01

    Using the method termed complex asteroseismology, we derive constraints on model atmospheres, in particular, on the NLTE effects. We fit simultaneously pulsational frequencies and the corresponding values of the nonadiabatic complex parameter f for the four \\beta Cephei stars: \\theta Oph, \

  1. Periodic Radio Continuum Emission Associated with the beta Cephei Star V2187 Cyg

    CERN Document Server

    Tapia, Mauricio; Tovmassian, Gagik; Rodriguez-Gomez, Vicente; Gonzalez-Buitrago, Diego; Zharikov, Sergei; Ortiz-Leon, Gisela N

    2014-01-01

    We present new optical time-resolved photometry and medium-resolution spectroscopy of V2187 Cyg. We confirm its classification as a beta Cephei star based on sinusoidal light variations with a period of 0.2539 days and mean amplitudes of 0.037 and 0.042 magnitudes in "i" and "V", respectively. We classified the spectrum of this star B2-3V with no evidence of variations in the profiles of its absorption lines in timescales of hours or days. The stellar spectrum is totally absent of emission lines. We detected unexpected faint radio continuum emission (between 0.4 and 0.8 mJy at 6-cm) showing a sinusoidal variation with a period of 12.8 days. The radio spectrum is thermal. We searched in the Very Large Array archive for radio continuum emission toward other 15 beta Cephei stars. None of these additional stars, some of them much closer to the Sun than V2187 Cyg, was detected, indicating that radio emission is extremely uncommon toward beta Cephei stars.

  2. The Paschen-Back effect in the Li I 6708 Å line and the presence of lithium in cool magnetic Ap stars

    Science.gov (United States)

    Kochukhov, O.

    2008-05-01

    Context: A number of cool magnetic Ap stars show a prominent feature at λ 6708 Å. Its identification with Li I remains controversial due to the lack of knowledge of the spectra of rare-earth elements that are strongly enhanced in peculiar stars so they can potentially provide an alternative identification. Aims: We suggest investigating the 6708 Å line in Ap stars with strong magnetic fields. In these objects, the magnetic broadening and splitting provides an additional, powerful criterium for line identification, allowing the whole line profile to be used instead of depending on a mere coincidence in the observed and predicted wavelengths. Methods: The small separation of the Li I doublet components means that their magnetic splitting pattern deviates from the one expected for the Zeeman effect, even in relatively weak fields. We carried out detailed calculations of the transition between the Zeeman and Paschen-Back regimes in the magnetic splitting of the Li I line and computed polarised synthetic spectra for the range of field strength expected in Ap stars. Theoretical spectral synthesis is compared with the high-resolution observations of cool Ap stars HD 116114, HD 166473, and HD 154708, which have a mean field strength of 6.4, 8.6, and 24.5 kG, respectively, and show a strong 6708 Å line. Results: High-resolution spectra for the 6708 Å region were analysed for 17 magnetic Ap stars. The presence of the 6708 Å line is confirmed for 9 stars and reported for the first time for 6 stars. The strength of the Li I doublet does not correlate with the absorption features of any other element. The stars HD 75445 and HD 201601 provide an extreme example of the two objects, which are dissimilar with respect to the 6708 Å line, but very close in the atmospheric parameters and abundances of other elements. We demonstrate that the observed profiles of the 6708 Å line in the strong field stars HD 116114, HD 166473, and HD 154708 correspond fairly well to the

  3. Associations of a polymorphic AP-2 binding site in the 5'-flanking region of the bovine beta-lactoglobulin gene with milk proteins.

    Science.gov (United States)

    Kuss, A W; Gogol, J; Geidermann, H

    2003-06-01

    Studies on a polymorphic position (R10) in an Activator-Protein-2 (AP-2) binding site of the bovine beta-Lactoglobulin (beta-Lg) gene promoter region and quantitative traits of individual milk proteins were based on material from 79 German Holstein Friesian (HF) and 61 Simmental (Sm) cows. At least four milk samples per cow were analyzed with alkaline Urea-PAGE in combination with densitometry for quantification of individual milk proteins. The two alleles of the R10 single nucleotide polymorphism (SNP) carry either G or C in position -435 bp of the beta-Lg promoter region. G- and C-alleles were found in Sm with nearly equal frequencies, while in HF the C-allele frequency was higher (0.73) than that of the G-allele. In both breeds, the R10 G-homozygotes had higher (P beta-Lg secreted per day and proportion of beta-Lg in milk protein compared with the C-homozygotes. A similar association was found for alpha-lactalbumin, whereas the relative proportions and daily secreted amounts of caseins (alphaS1, beta, kappa) showed lower values in beta-Lg R10 G-homozygotes. A positive association (P beta-Lg locus to a candidate gene for this trait. The association between the SNP in the AP-2 binding site of the beta-Lg gene and its gene product can be explained as the result of differences in protein binding activity, and, therefore, allele specific differences in gene expression. Thus, our study clearly links a DNA polymorphism of molecular function very closely with in vivo expression parameters of the same locus.

  4. Doppler imaging of chemical spots on magnetic Ap/Bp stars. Numerical tests and assessment of systematic errors

    CERN Document Server

    Kochukhov, O

    2016-01-01

    Doppler imaging (DI) is a powerful spectroscopic inversion technique that enables conversion of a line profile time series into a two-dimensional map of the stellar surface inhomogeneities. In this paper we investigate the accuracy of chemical abundance DI of Ap/Bp stars and assess the impact of several different systematic errors on the reconstructed spot maps. We simulate spectroscopic observational data for different spot distributions in the presence of a moderately strong dipolar magnetic field. We then reconstruct chemical maps using different sets of spectral lines and making different assumptions about line formation in the inversion calculations. Our numerical experiments demonstrate that a modern DI code successfully recovers the input chemical spot distributions comprised of multiple circular spots at different latitudes or an element overabundance belt at the magnetic equator. For the optimal reconstruction the average reconstruction errors do not exceed ~0.10 dex. The errors increase to about 0.1...

  5. Research study of Beta Cephei variable stars using data from OAO-2

    Science.gov (United States)

    Lesh, J. R.

    1975-01-01

    Photometric data from the Wisconsin Experiment package on OAO-2 were obtained for six Beta Cephei variable stars. The data were reduced in accordance with the OAO 2/Wisconsin Experiment Package Photometer Users Guide. For delta Cet and gamma Peg, there were enough data points to form reliable composite light curves at seven or eight ultraviolet wavelengths. The light curves are well represented by sine waves in phase with the blue light curve for each star. The amplitude of the light variation increases with shorter wavelengths. For theta Oph, epsilon Cen, eta Sco, and Lambda Sco, mean magnitudes and light ranges were obtained at several ultraviolet wavelengths. No significant differences were found between the mean, de-reddened ultraviolet colors of the observed stars, and the mean values for standard stars computed by Bottemiller. An attempt to derive a temperature scale from a comparison of the observed ultraviolet colors with Kurucz models was unsuccessful.

  6. Discovery of the magnetic field in the pulsating B star beta Cephei

    CERN Document Server

    Henrichs, H F; Verdugo, E; Schnerr, R S; Neiner, C; Donati, J -F; Catala, C; Shorlin, S L S; Wade, G A; Veen, P M; Nichols, J S; Damen, E M F; Talavera, A; Hill, G M; Kaper, L; Tijani, A M; Geers, V C; Wiersema, K; Plaggenborg, B; Rygl, K L J

    2013-01-01

    Although the star itself is not He enriched, the periodicity and the variability in the UV wind lines of the pulsating B1 IV star beta Cep are similar to what is observed in magnetic He-peculiar B stars, suggesting that beta Cep is magnetic. We searched for a magnetic field using spectropolarimetry. From UV spectroscopy, we analysed the wind variability and investigated the correlation with the magnetic data. Using 130 time-resolved circular polarisation spectra, obtained with the MuSiCoS spectropolarimeter at the 2m TBL from 1998 until 2005, we applied the least-squares deconvolution method on the Stokes V spectra and derived the longitudinal component of the integrated magnetic field over the visible hemisphere of the star. We performed a period analysis on the magnetic data and on EW measurements of UV wind lines obtained over 17 years. We also analysed the short- and long-term radial velocity variations, which are due to the pulsations and the 90-year binary motion. beta Cep hosts a sinusoidally varying m...

  7. EK Eridani: the tip of the iceberg of giants which have evolved from magnetic Ap stars

    CERN Document Server

    Aurière, M; Petit, P; Charbonnel, C; Dintrans, B; Lignières, F; Roudier, T; Alecian, E; Donati, J F; Landstreet, J D; Wade, G A

    2008-01-01

    We observe the slowly-rotating, active, single giant, EK Eri, to study and infer the nature of its magnetic field directly. We used the spectropolarimeter NARVAL at the Telescope Bernard Lyot, Pic du Midi Observatory, and the Least Square Deconvolution method to create high signal-to-noise ratio Stokes V profiles. We fitted the Stokes V profiles with a model of the large-scale magnetic field. We studied the classical activity indicators, the CaII H and K lines, the CaII infrared triplet, and H\\alpha line. We detected the Stokes V signal of EK Eri securely and measured the longitudinal magnetic field Bl for seven individual dates spanning 60% of the rotational period. The measured longitudinal magnetic field of EK Eri reached about 100 G and was as strong as fields observed in RSCVn or FK Com type stars: this was found to be extraordinary when compared with the weak fields observed at the surfaces of slowly-rotating MS stars or any single red giant previously observed with NARVAL. From our modeling, we infer t...

  8. Doppler imaging of chemical spots on magnetic Ap/Bp stars. Numerical tests and assessment of systematic errors

    Science.gov (United States)

    Kochukhov, O.

    2017-01-01

    Context. Doppler imaging (DI) is a powerful spectroscopic inversion technique that enables conversion of a line profile time series into a two-dimensional map of the stellar surface inhomogeneities. DI has been repeatedly applied to reconstruct chemical spot topologies of magnetic Ap/Bp stars with the goal of understanding variability of these objects and gaining an insight into the physical processes responsible for spot formation. Aims: In this paper we investigate the accuracy of chemical abundance DI and assess the impact of several different systematic errors on the reconstructed spot maps. Methods: We have simulated spectroscopic observational data for two different Fe spot distributions with a surface abundance contrast of 1.5 dex in the presence of a moderately strong dipolar magnetic field. We then reconstructed chemical maps using different sets of spectral lines and making different assumptions about line formation in the inversion calculations. Results: Our numerical experiments demonstrate that a modern DI code successfully recovers the input chemical spot distributions comprised of multiple circular spots at different latitudes or an element overabundance belt at the magnetic equator. For the optimal reconstruction based on half a dozen spectral intervals, the average reconstruction errors do not exceed 0.10 dex. The errors increase to about 0.15 dex when abundance distributions are recovered from a few and/or blended spectral lines. Ignoring a 2.5 kG dipolar magnetic field in chemical abundance DI leads to an average relative error of 0.2 dex and maximum errors of 0.3 dex. Similar errors are encountered if a DI inversion is carried out neglecting a non-uniform continuum brightness distribution and variation of the local atmospheric structure. None of the considered systematic effects lead to major spurious features in the recovered abundance maps. Conclusions: This series of numerical DI simulations proves that inversions based on one or two spectral

  9. Asteroseismology of the Beta Cephei star Nu Eridani: photometric observations and pulsational frequency analysis

    CERN Document Server

    Handler, G; Jerzykiewicz, M; Krisciunas, K; Tshenye, T; Rodríguez, E; Costa, V; Zhou, A Y; Medupe, R; Phorah, W M; Garrido, R; Amado, P J; Paparo, M; Zsuffa, D; Ramokgali, L; Crowe, R; Purves, N; Avila, R; Knight, R; Brassfield, E; Kilmartin, P M; Cottrell, P L

    2004-01-01

    We undertook a multisite photometric campaign for the Beta Cephei star Nu Eridani. More than 600 hours of differential photoelectric uvyV photometry were obtained with 11 telescopes during 148 clear nights. The frequency analysis of our measurements shows that the variability of Nu Eri can be decomposed into 23 sinusoidal components, eight of which correspond to independent pulsation frequencies between 5 - 8 c/d. Some of these are arranged in multiplets, which suggests rotational m-mode splitting of nonradial pulsation modes as the cause. If so, the rotation period of the star must be between 30 - 60 d. One of the signals in the light curves of Nu Eri has a very low frequency of 0.432 c/d. It can be a high-order combination frequency or, more likely, an independent pulsation mode. In the latter case Nu Eri would be both a Beta Cephei star and a slowly pulsating B (SPB) star. The photometric amplitudes of the individual pulsation modes of Nu Eri appear to have increased by about 20 per cent over the last 40 y...

  10. The Paschen-Back effect in the Li I 6708 A line and the presence of lithium in cool magnetic Ap stars

    CERN Document Server

    Kochukhov, O

    2008-01-01

    A number of cool magnetic Ap stars show a prominent feature at lambda 6708 A. Its identification with Li I remains controversial due to a poor knowledge of the spectra of rare-earth elements that are strongly enhanced in peculiar stars and can potentially provide an alternative identification. We suggest to investigate the 6708 line in Ap stars with strong magnetic fields. In these objects the magnetic broadening and splitting provides an additional powerful criterium for line identification, allowing to use the whole line profile instead of a mere coincidence of the observed and predicted wavelength. Due to a small separation of the Li I doublet components, their magnetic splitting pattern deviates from the one expected for the Zeeman effect even in relatively weak fields. We carry out detailed calculations of the transition between the Zeeman and Paschen-Back regimes in the magnetic splitting of the Li I line and compute polarized synthetic spectra for the range of field strength expected in Ap stars. Theor...

  11. A line-profile analysis of the large-amplitude beta Cephei star xi1 Canis Majoris

    NARCIS (Netherlands)

    Saesen, S.; Briquet, M.; Aerts, C.C.

    2006-01-01

    We present a detailed line-profile study of the beta Cephei star xi1 Canis Majoris, for which we have assembled numerous high-resolution spectra over a period of 4.5 years. It is the first time that the line-profile variations of this star have been analysed. We focused on the Si III line profiles c

  12. Detection of ultra-weak magnetic fields in Am stars: beta UMa and theta Leo

    CERN Document Server

    Blazère, A; Lignières, F; Aurière, M; ballot, J; Böhm, T; Folsom, C P; Gaurat, M; Jouve, L; Ariste, A Lopez; Neiner, C; Wade, G A

    2016-01-01

    An extremely weak circularly polarized signature was recently discovered in spectral lines of the chemically peculiar Am star Sirius A. A weak surface magnetic field was proposed to account for the observed polarized signal, but the shape of the phase-averaged signature, dominated by a prominent positive lobe, is not expected in the standard theory of the Zeeman effect. We aim at verifying the presence of weak circularly polarized signatures in two other bright Am stars, beta UMa and theta Leo, and investigating the physical origin of Sirius-like polarized signals further. We present here a set of deep spectropolarimetric observations of beta UMa and theta Leo, observed with the NARVAL spectropolarimeter. We analyzed all spectra with the Least Squares Deconvolution multiline procedure. To improve the signal-to-noise ratio and detect extremely weak signatures in Stokes V profiles, we co-added all available spectra of each star (around 150 observations each time). Finally, we ran several tests to evaluate wheth...

  13. Luminosity control and beam orbit stability with beta star leveling at LHC and HL-LHC

    CERN Document Server

    Gorzawski, Arkadiusz Andrzej; Wenninger, Jorg

    This thesis describes the wide subject of the luminosity leveling and its requirements for the LHC and the HL-LHC. We discuss the advantages and disadvantages of different leveling methods focusing the thesis on the beta star leveling technique. We review the beams offset build--up due to the environmental (i.e. natural ground motion) and mechanical (i.e. moving quadrupole) sources. We quantify the instrumentation requirements for the reliable and reproducible operation with small offsets at the interaction points. Last but not least, we propose a novel method for the beam offset stabilization at the collision point based on the feedback from the luminosity.

  14. Star formation triggered by SN explosions: an application to the stellar association of $\\beta$ Pictoris

    CERN Document Server

    Melioli, C; De la Reza, R; Raga, A

    2006-01-01

    In the present study, considering the physical conditions that are relevant in interactions between supernova remnants (SNRs) and dense molecular clouds for triggering star formation we have built a diagram of SNR radius versus cloud density in which the constraints above delineate a shaded zone where star formation is allowed. We have also performed fully 3-D radiatively cooling numerical simulations of the impact between SNRs and clouds under different initial conditions in order to follow the initial steps of these interactions. We determine the conditions that may lead either to cloud collapse and star formation or to complete cloud destruction and find that the numerical results are consistent with those of the SNR-cloud density diagram. Finally, we have applied the results above to the $\\beta-$Pictoris stellar association which is composed of low mass Post-T Tauri stars with an age of 11 Myr. It has been recently suggested that its formation could have been triggered by the shock wave produced by a SN e...

  15. Abundance of nine beta Cephei stars (Morel+, 2006) g spectroscopy with Ta/Al DROIDs: performance for different geometries

    NARCIS (Netherlands)

    Morel, T.; Butler, K.; Aerts, C.C.; Neiner, C.; Briquet, M.; Hijmering, R.A.; Jerjen, I.; Verhoeve, P.; Martin, D.D.E.; Peacock, A.; Kozorezov, A.G.; Venn, R.

    2006-01-01

    The equivalent widths (EWs) were measured on high-resolution spectra obtained with various echelle spectrographs (see Table 2 of paper for further details). Our EWs are systematically larger than the values quoted by Gies & Lambert (1992ApJ...387..673G) for the seven stars in common, but a similar t

  16. Discovery of a brown dwarf companion to the A3V star \\beta{} Circini

    CERN Document Server

    Smith, L C; Peña, C Contreras; Kurtev, R; Marocco, F; Jones, H R A; Beamin, J C; Napiwotzki, R; Borissova, J; Burningham, B; Faherty, J; Pinfield, D J; Gromadzki, M; Ivanov, V D; Minniti, D; Stimson, W; Villanueva, V

    2015-01-01

    We report the discovery of an L dwarf companion to the A3V star \\beta{} Circini. VVV J151721.49-585131.5, or \\beta{} Cir B, was identified in a proper motion and parallax catalogue of the Vista Variables in the V\\'{i}a L\\'{a}ctea survey as having near infrared luminosity and colour indicative of an early L dwarf, and a proper motion and parallax consistent with that of \\beta{} Cir. The projected separation of $\\sim$3.6' corresponds to $6656$ au, which is unusually wide. The most recent published estimate of the age of the primary combined with our own estimate based on newer isochrones yields an age of $370-500$ Myr. The system therefore serves as a useful benchmark at an age greater than that of the Pleiades brown dwarfs and most other young L dwarf benchmarks. We have obtained a medium resolution echelle spectrum of the companion which indicates a spectral type of L1.0$\\pm$0.5 and lacks the typical signatures of low surface gravity seen in younger brown dwarfs. This suggests that signs of low surface gravit...

  17. Evolution of Intermediate-mass X-Ray Binaries Driven by the Magnetic Braking of AP/BP Stars. I. Ultracompact X-Ray Binaries

    Science.gov (United States)

    Chen, Wen-Cong; Podsiadlowski, Philipp

    2016-10-01

    It is generally believed that ultracompact X-ray binaries (UCXBs) evolved from binaries consisting of a neutron star accreting from a low-mass white dwarf (WD) or helium star where mass transfer is driven by gravitational radiation. However, the standard WD evolutionary channel cannot produce the relatively long-period (40-60 minutes) UCXBs with a high time-averaged mass-transfer rate. In this work, we explore an alternative evolutionary route toward UCXBs, where the companions evolve from intermediate-mass Ap/Bp stars with an anomalously strong magnetic field (100-10,000 G). Including the magnetic braking caused by the coupling between the magnetic field and an irradiation-driven wind induced by the X-ray flux from the accreting component, we show that intermediate-mass X-ray binaries (IMXBs) can evolve into UCXBs. Using the MESA code, we have calculated evolutionary sequences for a large number of IMXBs. The simulated results indicate that, for a small wind-driving efficiency f = 10-5, the anomalous magnetic braking can drive IMXBs to an ultra-short period of 11 minutes. Comparing our simulated results with the observed parameters of 15 identified UCXBs, the anomalous magnetic braking evolutionary channel can account for the formation of seven and eight sources with f = 10-3, and 10-5, respectively. In particular, a relatively large value of f can fit three of the long-period, persistent sources with a high mass-transfer rate. Though the proportion of Ap/Bp stars in intermediate-mass stars is only 5%, the lifetime of the UCXB phase is ≳2 Gyr, producing a relatively high number of observable systems, making this an alternative evolutionary channel for the formation of UCXBs.

  18. The null result of a search for pulsational variations of the surface magnetic field in the roAp star gamma Equulei

    CERN Document Server

    Kochukhov, O P; Landstreet, J D; Weiss, W W

    2004-01-01

    We describe an analysis of the time-resolved measurements of the surface magnetic field in the roAp star gamma Equ. We have obtained a high-resolution and high S/N spectroscopic time-series, and the magnetic field was determined using Zeeman resolved profiles of the Fe II 6149.25 A and Fe I 6173.34 A lines. Contrary to recent reports we do not find any evidence of magnetic variability with pulsation phase, and derive an upper limit of 5-10 G for pulsational modulation of the surface magnetic field in gamma Equ.

  19. The Relation Between [OIII]/H$\\beta$ and Specific Star Formation Rate in Galaxies at $z \\sim 2$

    CERN Document Server

    Dickey, Claire Mackay; Oesch, Pascal; Whitaker, Katherine; Momcheva, Ivelina; Nelson, Erica; Leja, Joel; Brammer, Gabriel; Franx, Marijn; Skelton, Rosalind

    2016-01-01

    Recent surveys have identified a seemingly ubiquitous population of galaxies with elevated [OIII]/H$\\beta$ emission line ratios at $z > 1$, though the nature of this phenomenon continues to be debated. The [OIII]/H$\\beta$ line ratio is of interest because it is a main component of the standard diagnostic tools used to differentiate between active galactic nuclei (AGN) and star-forming galaxies, as well as the gas-phase metallicity indicators $O_{23}$ and $R_{23}$. Here, we investigate the primary driver of increased [OIII]/H$\\beta$ ratios by median-stacking rest-frame optical spectra for a sample of star-forming galaxies in the 3D-HST survey in the redshift range $z\\sim1.4-2.2$. Using $N = 4220$ star-forming galaxies, we stack the data in bins of mass and specific star formation rates (sSFR) respectively. After accounting for stellar Balmer absorption, we measure [OIII]$\\lambda5007$\\AA/H$\\beta$ down to $\\mathrm{M} \\sim 10^{9.2} \\ \\mathrm{M_\\odot}$ and sSFR $\\sim 10^{-9.6} \\ \\mathrm{yr}^{-1}$, more than an ord...

  20. The fundamental parameters of the roAp star HD 24712. A rapidly oscillator at the red edge of the instability strip

    Science.gov (United States)

    Perraut, K.; Brandão, I.; Cunha, M.; Shulyak, D.; Mourard, D.; Nardetto, N.; ten Brummelaar, T. A.

    2016-05-01

    Context. There is still a debate about the nature of the mechanism that causes the pulsation excitation of the rapidly oscillating Ap stars that oscillate above the highest theoretically acoustic frequency. HD 24712 is a good test case for such a study because it is bright, its parallax accurately determined, and its frequency spectrum is well known. Aims: Visible long-baseline interferometry is a unique technique for measuring accurate angular diameters of targets as small as the brightest roAp stars, and thus estimating accurate radii by a method as independent as possible of atmosphere models. Methods: We used the visible spectrograph VEGA at the CHARA long-baseline optical array to observe HD 24712, and we derived its limb-darkened diameter. We also estimated its bolometric flux from spectroscopic data in the literature and determined its radius, luminosity, and effective temperature. Results: We determined a limb-darkened angular diameter of 0.335 ± 0.009 mas for HD 24712 and derived a radius of R = 1.772 ± 0.057 R⊙, a luminosity of L = 7.2 ± 1.8 L⊙, and an effective temperature of Teff = 7235 ± 280 K, which is in very close agreement with the values provided by the self-consistent stratified model developed for this star. We used these fundamental parameters to set HD 24712 in the Hertzsprung-Russell diagram. Its position is marginally consistent with the region where high radial order modes are predicted to be excited by the κ-mechanism. Conclusions: We conclude that oscillations in this star are most likely not driven by the κ-mechanism. Based on observations made with the VEGA/CHARA spectro-interferometer.

  1. The Bursty Star Formation Histories of Low-mass Galaxies at $0.4Star Formation Rates Measured from FUV and H$\\beta$

    CERN Document Server

    Guo, Yicheng; Faber, S M; Koo, David C; Krumholz, Mark R; Trump, Jonathan R; Willner, S P; Amorín, Ricardo; Barro, Guillermo; Bell, Eric F; Gardner, Jonathan P; Gawiser, Eric; Hathi, Nimish P; Koekemoer, Anton M; Pacifici, Camilla; Pérez-González, Pablo G; Ravindranath, Swara; Reddy, Naveen; Teplitz, Harry I; Yesuf, Hassen

    2016-01-01

    We investigate the burstiness of star formation histories (SFHs) of galaxies at $0.4star formation rates (SFRs) measured from FUV (1500 \\AA) and H$\\beta$ (FUV--to--H$\\beta$ ratio). Our sample contains 164 galaxies down to stellar mass (M*) of $10^{8.5} M_\\odot$ in the CANDELS GOODS-N region, where TKRS Keck/DEIMOS spectroscopy and HST/WFC3 F275W images from CANDELS and HDUV are available. When the ratio of FUV- and H$\\beta$-derived SFRs is measured, dust extinction correction is negligible (except for very dusty galaxies) with the Calzetti attenuation curve. The FUV--to--H$\\beta$ ratio of our sample increases with the decrease of M* and SFR. The median ratio is $\\sim$1 at M* $\\sim 10^{10} M_\\odot$ (or SFR = 20 $M_\\odot$/yr) and increases to $\\sim$1.6 at M* $\\sim 10^{8.5} M_\\odot$ (or SFR $\\sim 0.5 M_\\odot$/yr). At M* $< 10^{9.5} M_\\odot$, our median FUV--to--H$\\beta$ ratio is higher than that of local galaxies at the same M*, implying a redshift evolution. Bursty SFH on a ...

  2. B fields in OB stars (BOB): on the detection of weak magnetic fields in the two early B-type stars beta CMa and epsilon CMa

    CERN Document Server

    Fossati, L; Morel, T; Langer, N; Briquet, M; Carroll, T A; Hubrig, S; Nieva, M F; Oskinova, L M; Przybilla, N; Schneider, F R N; Scholler, M; Simon-Diaz, S; Ilyin, I; de Koter, A; Reisenegger, A; Sana, H

    2014-01-01

    Within the context of the "B fields in OB stars (BOB)" collaboration, we used the HARPSpol spectropolarimeter to observe the early B-type stars beta CMa (HD44743; B1 II/III) and epsilon CMa (HD52089; B1.5 II). For both stars, we consistently detected the signature of a weak (<30 G in absolute value) longitudinal magnetic field. We determined the physical parameters of both stars and characterise their X-ray spectrum. For beta CMa, our mode identification analysis led to determining a rotation period of 13.6+/-1.2 days and of an inclination angle of the rotation axis of 57.6+/-1.7 degrees, with respect to the line of sight. On the basis of these measurements and assuming a dipolar field geometry, we derived a best fitting obliquity of ~22 degrees and a dipolar magnetic field strength (Bd) of ~100 G (60stars. For epsilon CMa we could only determine a lower limit on the dipolar magnetic field strength of 13 G. For this s...

  3. Investigation of the magnetic field characteristics of Herbig Ae/Be stars: Discovery of the pre-main sequence progenitors of the magnetic Ap/Bp stars

    CERN Document Server

    Wade, G A; Bagnulo, S; Landstreet, J D; Mason, E; Silvester, J; Alecian, E; Böhm, T; Bouret, J C; Catala, C; Donati, J F; Folsom, C; Bale, K

    2006-01-01

    We are investigating the magnetic characteristics of pre-main sequence Herbig Ae/Be stars, with the aim of (1) understanding the origin and evolution of magnetism in intermediate-mass stars, and (2) exploring the influence of magnetic fields on accretion, rotation and mass-loss at the early stages of evolution of A, B and O stars. We have begun by conducting 2 large surveys of Herbig Ae/Be stars, searching for direct evidence of photospheric magnetic fields via the longitudinal Zeeman effect. From observations obtained using FORS1 at the ESO-VLT and ESPaDOnS at the Canada-France-Hawaii Telescope, we report the confirmed detection of magnetic fields in 4 pre-main sequence A- and B-type stars, and the apparent (but as yet unconfirmed) detection of fields in 2 other such stars. We do not confirm the detection of magnetic fields in several stars reported by other authors to be magnetic: HD 139614, HD 144432 or HD 31649. One of the most evolved stars in the detected sample, HD 72106A, shows clear evidence of stron...

  4. Searching for young Jupiter analogs around AP Col: L-band high-contrast imaging of the closest pre-main sequence star

    CERN Document Server

    Quanz, Sascha P; Janson, Markus; Avenhaus, Henning; Meyer, Michael R; Hillenbrand, Lynne A

    2012-01-01

    The nearby M-dwarf AP Col was recently identified by Riedel et al. 2011 as a pre-main sequence star (age 12 - 50 Myr) situated only 8.4 pc from the Sun. The combination of its youth, distance, and intrinsically low luminosity make it an ideal target to search for extrasolar planets using direct imaging. We report deep adaptive optics observations of AP Col taken with VLT/NACO and Keck/NIRC2 in the L-band. Using aggressive speckle suppression and background subtraction techniques, we are able to rule out companions with mass m >= 0.5 - 1M_Jup for projected separations a>4.5 AU, and m >= 2 M_Jup for projected separations as small as 3 AU, assuming an age of 40 Myr using the COND theoretical evolutionary models. Using a different set of models the mass limits increase by a factor of ~2. The observations presented here are the deepest mass-sensitivity limits yet achieved within 20 AU on a star with direct imaging. While Doppler radial velocity surveys have shown that Jovian bodies with close-in orbits are rare ar...

  5. Evolution of intermediate-mass X-ray binaries driven by magnetic braking of Ap/Bp stars: I. ultracompact X-ray binaries

    CERN Document Server

    Chen, Wen-Cong

    2016-01-01

    It is generally believed that Ultracompact X-ray binaries (UCXBs) evolved from binaries consisting of a neutron star accreting from a low-mass white dwarf or helium star where mass transfer is driven by gravitational radiation. However, the standard white-dwarf evolutionary channel cannot produce the relatively long-period ($40 - 60$\\,min) UCXBs with high time-averaged mass-transfer rate. In this work, we explore an alternative evolutionary route toward UCXBs where the companions evolve from intermediate-mass Ap/Bp stars with an anomalously strong magnetic field ($100 - 10000$\\,G). Including the magnetic braking caused by the coupling between the magnetic field and an irradiation-driven wind induced by the X-ray flux from the accreting component, we show that intermediate-mass X-ray binaries (IMXBs) can evolve into UCXBs. Using the \\emph{MESA} code, we have calculated evolutionary sequences for a large number of IMXBs. The simulated results indicate that, for a small wind-driving efficiency $f=10^{-5}$, the a...

  6. An ancient repeat sequence in the ATP synthase beta-subunit gene of forcipulate sea stars.

    Science.gov (United States)

    Foltz, David W

    2007-11-01

    A novel repeat sequence with a conserved secondary structure is described from two nonadjacent introns of the ATP synthase beta-subunit gene in sea stars of the order Forcipulatida (Echinodermata: Asteroidea). The repeat is present in both introns of all forcipulate sea stars examined, which suggests that it is an ancient feature of this gene (with an approximate age of 200 Mya). Both stem and loop regions show high levels of sequence constraint when compared to flanking nonrepetitive intronic regions. The repeat was also detected in (1) the family Pterasteridae, order Velatida and (2) the family Korethrasteridae, order Velatida. The repeat was not detected in (1) the family Echinasteridae, order Spinulosida, (2) the family Astropectinidae, order Paxillosida, (3) the family Solasteridae, order Velatida, or (4) the family Goniasteridae, order Valvatida. The repeat lacks similarity to published sequences in unrestricted GenBank searches, and there are no significant open reading frames in the repeat or in the flanking intron sequences. Comparison via parametric bootstrapping to a published phylogeny based on 4.2 kb of nuclear and mitochondrial sequence for a subset of these species allowed the null hypothesis of a congruent phylogeny to be rejected for each repeat, when compared separately to the published phylogeny. In contrast, the flanking nonrepetitive sequences in each intron yielded separate phylogenies that were each congruent with the published phylogeny. In four species, the repeat in one or both introns has apparently experienced gene conversion. The two introns also show a correlated pattern of nucleotide substitutions, even after excluding the putative cases of gene conversion.

  7. Asteroseismology of the Beta Cephei star 12 (DD) Lacertae: photometric observations, pulsational frequency analysis and mode identification

    CERN Document Server

    Handler, G; Rodríguez, E; Uytterhoeven, K; Amado, P J; Dorokhova, T N; Dorokhov, N I; Poretti, E; Sareyan, J P; Parrao, L; Lorenz, D; Zsuffa, D; Drummond, R; Daszynska-Daszkiewicz, J; Verhoelst, T; De Ridder, J; Acke, B; Bourge, P O; Movchan, A I; Garrido, R; Paparo, M; Sahin, T; Antoci, V; Udovichenko, S N; Csorba, K; Crowe, R; Berkey, B; Stewart, S; Terry, D; Mkrtichian, D E; Aerts, C

    2006-01-01

    We report a multisite photometric campaign for the Beta Cephei star 12 Lacertae. 750 hours of high-quality differential photoelectric Stromgren, Johnson and Geneva time-series photometry were obtained with 9 telescopes during 190 nights. Our frequency analysis results in the detection of 23 sinusoidal signals in the light curves. Eleven of those correspond to independent pulsation modes, and the remainder are combination frequencies. We find some slow aperiodic variability such as that seemingly present in several Beta Cephei stars. We perform mode identification from our colour photometry, derive the spherical degree l for the five strongest modes unambiguously and provide constraints on l for the weaker modes. We find a mixture of modes of 0 <= l <= 4. In particular, we prove that the previously suspected rotationally split triplet within the modes of 12 Lac consists of modes of different l; their equal frequency splitting must thus be accidental. One of the periodic signals we detected in the light c...

  8. The Mass of the Planet-hosting Giant Star Beta Geminorum Determined from its p-mode Oscillation Spectrum

    CERN Document Server

    Hatzes, A P; Matthews, J; Kuschnig, R; Walker, G A H; Doellinger, M; Guenther, D B; Moffat, A F J; Rucinski, S M; Sasselov, D

    2012-01-01

    We use precise radial velocity measurements and photometric data to derive the frequency spacing of the p-mode oscillation spectrum of the planet-hosting star Beta Gem. This spacing along with the interferometric radius for this star is used to derive an accurate stellar mass. A long time series of over 60 hours of precise stellar radial velocity measurements of Beta Gem were taken with an iodine absorption cell and the echelle spectrograph mounted on the 2m Alfred Jensch Telescope. Complementary photometric data for this star were also taken with the MOST microsatellite spanning 3.6 d. A Fourier analysis of the radial velocity data reveals the presence of up to 17 significant pulsation modes in the frequency interval 10-250 micro-Hz. Most of these fall on a grid of equally-spaced frequencies having a separation of 7.14 +/- 0.12 micro-Hz. An analysis of 3.6 days of high precision photometry taken with the MOST space telescope shows the presence of up to 16 modes, six of which are consistent with modes found i...

  9. On the use of rotational splitting asymmetries to probe the internal rotation profile of stars. Application to $\\beta$ Cephei stars

    CERN Document Server

    Suárez, J C; Goupil, M J; Janot-Pacheco, E

    2010-01-01

    Rotationally-split modes can provide valuable information about the internal rotation profile of stars. This has been used for years to infer the internal rotation behavior of the Sun. The present work discusses the potential additional information that rotationally splitting asymmetries may provide when studying the internal rotation profile of stars. We present here some preliminary results of a method, currently under development, which intends: 1) to understand the variation of the rotational splitting asymmetries in terms of physical processes acting on the angular momentum distribution in the stellar interior, and 2) how this information can be used to better constrain the internal rotation profile of the stars. The accomplishment of these two objectives should allow us to better use asteroseismology as a test-bench of the different theories describing the angular momentum distribution and evolution in the stellar interiors.

  10. Erratum to Star formation triggered by SN explosions: an application to the stellar association of $\\beta$Pictoris

    CERN Document Server

    Melioli, C; Leão, M R M; De la Reza, R; Raga, A

    2007-01-01

    In the present study, considering the physical conditions that are relevant interactions between supernova remnants (SNRs) and dense molecular clouds for triggering star formation we have built a diagram of SNR radius versus cloud density in which the constraints above delineate a shaded zone where star formation is allowed. We have also performed fully 3-D radiatively cooling numerical simulations of the impact between SNRs and clouds under different initial conditions in order to follow the initial steps of these interactions. We determine the conditions that may lead either to cloud collapse and star formation or to complete cloud destruction and find that the numerical results are consistent with those of the SNR-cloud density diagram. Finally, we have applied the results above to the $\\beta-$ Pictoris stellar association which is composed of low mass Post-T Tauri stars with an age of 11 Myr. It has been recently suggested that its formation could have been triggered by the shock wave produced by a SN exp...

  11. Three-dimensional magnetic and abundance mapping of the cool Ap star HD 24712 I. Spectropolarimetric observations in all four Stokes parameters

    CERN Document Server

    Rusomarov, N; Piskunov, N; Jeffers, S V; Johns-Krull, C M; Keller, C U; Makaganiuk, V; Rodenhuis, M; Snik, F; Stempels, H C; Valenti, J A

    2013-01-01

    High-resolution spectropolarimetric observations provide simultaneous information about stellar magnetic field topologies and three-dimensional distributions of chemical elements. Here we present analysis of a unique full Stokes vector spectropolarimetric data set, acquired for the cool magnetic Ap star HD 24712. The goal of our work is to examine circular and linear polarization signatures inside spectral lines and to study variation of the stellar spectrum and magnetic observables as a function of rotational phase. HD 24712 was observed with the HARPSpol instrument at the 3.6-m ESO telescope over a period of 2010-2011. The resulting spectra have S/N ratio of 300-600 and resolving power exceeding 100000. The multiline technique of least-squares deconvolution (LSD) was applied to combine information from the spectral lines of Fe-peak and rare-earth elements. We used the HARPSPol spectra of HD 24712 to study the morphology of the Stokes profile shapes in individual spectral lines and in LSD Stokes profiles cor...

  12. A high-resolution spectroscopy survey of beta Cephei pulsations in bright stars

    NARCIS (Netherlands)

    Telting, J.H.; Schrijvers, C.; Ilyin, I.V.; Uytterhoeven, K.; Ridder, J. de; Aerts, C.C.; Henrichs, H.F.

    2006-01-01

    We present a study of absorption line-profile variations in early-B type near-main-sequence stars without emission lines. We have surveyed a total of 171 bright stars using the Nordic Optical Telescope (NOTSA), William Herschel Telescope (ING) and Coud�uxiliary Telescope (ESO). Our sample contains 7

  13. Numerical Evidence for Dark Star Formation: A Comment on "Weakly Interacting Massive Particle Dark Matter and First Stars: Suppression of Fragmentation in Primordial Star Formation" by Smith et al. 2012, ApJ 761, 154

    CERN Document Server

    Gondolo, Paolo; Spolyar, Douglas; Bodenheimer, Peter

    2013-01-01

    (abridged) This comment is intended to show that simulations by Smith et al. (S12) support the Dark Star (DS) scenario and even remove some potential obstacles. Our previous work illustrated that the initial hydrogen densities of the first equilibrium DSs are high, ~10^{17}/cm^3 for the case of 100 GeV WIMPs, with a stellar radius of ~2-3 AU. Subsequent authors have somehow missed the fact that equilibrium DSs have the high densities they do. S12 have numerically simulated the effect of dark matter annihilation on the contraction of a protostellar gas cloud en route to forming the first stars. They show results at a density ~5 10^{14}/cm^3, slightly higher than the value at which annihilation heating prevails over cooling. However, they are apparently unable to reach the ~10^{17}/cm^3 density of our hydrostatic DS solutions. We are in complete agreement with their physical result that the gas keeps collapsing to densities > 5 10^{14}/cm^3, as it must before equilibrium DSs can form. However we are in disagree...

  14. Massive pulsating stars observed by BRITE-Constellation. I. The triple system Beta Centauri (Agena)

    CERN Document Server

    Pigulski, A; Popowicz, A; Kuschnig, R; Moffat, A F J; Rucinski, S M; Schwarzenberg-Czerny, A; Weiss, W W; Handler, G; Wade, G A; Koudelka, O; Matthews, J M; Mochnacki, St; Orleański, P; Pablo, H; Ramiaramanantsoa, T; Whittaker, G; Zocłońska, E; Zwintz, K

    2016-01-01

    This paper aims to precisely determine the masses and detect pulsation modes in the two massive components of Beta Cen with BRITE-Constellation photometry. In addition, seismic models for the components are considered and the effects of fast rotation are discussed. This is done to test the limitations of seismic modeling for this very difficult case. A simultaneous fit of visual and spectroscopic orbits is used to self-consistently derive the orbital parameters, and subsequently the masses, of the components. The derived masses are equal to 12.02 +/- 0.13 and 10.58 +/- 0.18 M_Sun. The parameters of the wider, A - B system, presently approaching periastron passage, are constrained. Analysis of the combined blue- and red-filter BRITE-Constellation photometric data of the system revealed the presence of 19 periodic terms, of which eight are likely g modes, nine are p modes, and the remaining two are combination terms. It cannot be excluded that one or two low-frequency terms are rotational frequencies. It is pos...

  15. Endoplasmic reticulum stress mediating downregulated StAR and 3-beta-HSD and low plasma testosterone caused by hypoxia is attenuated by CPU86017-RS and nifedipine

    Directory of Open Access Journals (Sweden)

    Liu Gui-Lai

    2012-01-01

    Full Text Available Abstract Background Hypoxia exposure initiates low serum testosterone levels that could be attributed to downregulated androgen biosynthesizing genes such as StAR (steroidogenic acute regulatory protein and 3-beta-HSD (3-beta-hydroxysteroid dehydrogenase in the testis. It was hypothesized that these abnormalities in the testis by hypoxia are associated with oxidative stress and an increase in chaperones of endoplasmic reticulum stress (ER stress and ER stress could be modulated by a reduction in calcium influx. Therefore, we verify that if an application of CPU86017-RS (simplified as RS, a derivative to berberine could alleviate the ER stress and depressed gene expressions of StAR and 3-beta-HSD, and low plasma testosterone in hypoxic rats, these were compared with those of nifedipine. Methods Adult male Sprague-Dawley rats were randomly divided into control, hypoxia for 28 days, and hypoxia treated (mg/kg, p.o. during the last 14 days with nifedipine (Nif, 10 and three doses of RS (20, 40, 80, and normal rats treated with RS isomer (80. Serum testosterone (T and luteinizing hormone (LH were measured. The testicular expressions of biomarkers including StAR, 3-beta-HSD, immunoglobulin heavy chain binding protein (Bip, double-strand RNA-activated protein kinase-like ER kinase (PERK and pro-apoptotic transcription factor C/EBP homologous protein (CHOP were measured. Results In hypoxic rats, serum testosterone levels decreased and mRNA and protein expressions of the testosterone biosynthesis related genes, StAR and 3-beta-HSD were downregulated. These changes were linked to an increase in oxidants and upregulated ER stress chaperones: Bip, PERK, CHOP and distorted histological structure of the seminiferous tubules in the testis. These abnormalities were attenuated significantly by CPU86017-RS and nifedipine. Conclusion Downregulated StAR and 3-beta-HSD significantly contribute to low testosterone in hypoxic rats and is associated with ER stress

  16. Multitechnique testing of the viscous decretion disk model I. The stable and tenuous disk of the late-type Be star $\\beta$ CMi

    CERN Document Server

    Klement, R; Rivinius, T; Panoglou, D; Vieira, R G; Bjorkman, J E; Štefl, S; Tycner, C; Faes, D M; Korčáková, D; Müller, A; Zavala, R T; Curé, M

    2015-01-01

    The viscous decretion disk (VDD) model is able to explain most of the currently observable properties of the circumstellar disks of Be stars. However, more stringent tests, focusing on reproducing multitechnique observations of individual targets via physical modeling, are needed to study the predictions of the VDD model under specific circumstances. In the case of nearby, bright Be star $\\beta$ CMi, these circumstances are a very stable low-density disk and a late-type (B8Ve) central star. The aim is to test the VDD model thoroughly, exploiting the full diagnostic potential of individual types of observations, in particular, to constrain the poorly known structure of the outer disk if possible, and to test truncation effects caused by a possible binary companion using radio observations. We use the Monte Carlo radiative transfer code HDUST to produce model observables, which we compare with a very large set of multitechnique and multiwavelength observations that include ultraviolet and optical spectra, photo...

  17. Understanding the dynamical structure of pulsating stars: The center-of-mass velocity and the Baade-Wesselink projection factor of the beta-Cephei star alpha-Lupi

    CERN Document Server

    Nardetto, N; Fokin, A; Chapellier, E; Pietrzynski, G; Gieren, W; Graczyk, D; Mourard, D

    2013-01-01

    High-resolution spectroscopy of pulsating stars is a powerful tool to study the dynamical structure of their atmosphere. Lines asymmetry is used to derive the center-of-mass velocity of the star, while a direct measurement of the atmospheric velocity gradient helps determine the projection factor used in the Baade-Wesselink method of distance determination. We aim at deriving the center-of-mass velocity and the projection factor of the beta-Cephei star alpha-Lup. We present HARPS high spectral resolution observations of alpha-Lup. We calculate the first-moment radial velocities and fit the spectral line profiles by a bi-Gaussian to derive line asymmetries. Correlations between the gamma-velocity and the gamma-asymmetry (defined as the average values of the radial velocity and line asymmetry curves respectively) are used to derive the center-of-mass velocity of the star. By combining our spectroscopic determination of the atmospheric velocity gradient with a hydrodynamical modelof the photosphere of the star, ...

  18. A Coherent Study of Emission Lines from Broad-Band Photometry: Specific Star-Formation Rates and [OIII]/H{\\beta} Ratio at 3 < z < 6

    CERN Document Server

    Faisst, A L; Hsieh, B C; Laigle, C; Salvato, M; Tasca, L; Cassata, P; Davidzon, I; Ilbert, O; Fevre, O Le; Masters, D; McCracken, H J; Steinhardt, C; Silverman, J D; De Barros, S; Hasinger, G; Scoville, N Z

    2016-01-01

    We measure the H{\\alpha} and [OIII] emission line properties as well as specific star-formation rates (sSFR) of spectroscopically confirmed 33 cannot be fully explained in a picture of cold accretion driven growth. We find a progressively increasing [OIII]{\\lambda}5007/H{\\beta} ratio out to z~6, consistent with the ratios in local galaxies selected by increasing H{\\alpha} EW (i.e., sSFR). This demonstrates the potential of using "local high-z analogs" to investigate the spectroscopic properties and relations of galaxies in the re-ionization epoch.

  19. Nearby young stars selected by proper motion. I. Four new members of the Beta Pictoris moving group from the Tycho-2 catalog

    CERN Document Server

    Lepine, Sebastien

    2008-01-01

    We describe a procedure to identify stars from nearby moving groups and associations out of catalogs of stars with large proper motions. We show that from the mean motion vector of a known or suspected moving group, one can identify additional members of the group based on proper motion data and photometry in the optical and infrared, with minimal contamination from background field stars. We demonstrate the technique by conducting a search for low-mass members of the Beta Pictoris Moving Group in the Tycho-2 catalog. All known members of the moving group are easily recovered, and a list of 51 possible candidates is generated. Moving group membership is evaluated for 33 candidates based on X-ray flux from ROSAT, Halpha line emission, and radial velocity measurement from high-resolution infrared spectra obtained at IRTF. We confirm three of the candidates to be new members of the group: TYC 1186-706-1, TYC 7443-1102-1, and TYC 2211-1309-1 which are late-K and early-M dwarfs 45pc-60pc from the Sun. We also iden...

  20. Three-dimensional magnetic and abundance mapping of the cool Ap star HD 24712 II. Two-dimensional Magnetic Doppler Imaging in all four Stokes parameters

    CERN Document Server

    Rusomarov, N; Ryabchikova, T; Piskunov, N

    2014-01-01

    Aims: We present a magnetic Doppler imaging study from all Stokes parameters of the cool, chemically peculiar star HD 24712. This is the very first such analysis performed at a resolving power exceeding 10^5. Methods: The analysis is performed on the basis of phase-resolved observations of line profiles in all four Stokes parameters obtained with the HARPSpol instrument attached at the 3.6-m ESO telescope. We use the magnetic Doppler imaging code, INVERS10, which allows us to derive the magnetic field geometry and surface chemical abundance distributions simultaneously. Results: We report magnetic maps of HD 24712 recovered from a selection of FeI, FeII, NdIII, and NaI lines with strong polarization signals in all Stokes parameters. Our magnetic maps successfully reproduce most of the details available from our observation data. We used these magnetic field maps to produce abundance distribution map of Ca. This new analysis shows that the surface magnetic field of HD 24712 has a dominant dipolar component wit...

  1. Combining BRITE and ground-based photometry for the Beta Cephei star Nu Eridani: impact on photometric pulsation mode identification and detection of several g modes

    CERN Document Server

    Handler, G; Popowicz, A; Pigulski, A; Kuschnig, R; Zoclonska, E; Moffat, A F J; Weiss, W W; Grant, C C; Pablo, H; Whittaker, G N; Rucinski, S M; Ramiaramanantsoa, T; Zwintz, K; Wade, G A

    2016-01-01

    We report a simultaneous ground and space-based photometric study of the Beta Cephei star Nu Eridani. Half a year of observations have been obtained by four of the five satellites constituting BRITE-Constellation, supplemented with ground-based photoelectric photometry. We show that carefully combining the two data sets virtually eliminates the aliasing problem that often hampers time-series analyses. We detect 40 periodic signals intrinsic to the star in the light curves. Despite a lower detection limit we do not recover all the pressure and mixed modes previously reported in the literature, but we newly detect six additional gravity modes. This behaviour is a consequence of temporal changes in the pulsation amplitudes that we also detected for some of the p modes. We point out that the dependence of theoretically predicted pulsation amplitude on wavelength is steeper in visual passbands than those observationally measured, to the extent that the three dominant pulsation modes of Nu Eridani would be incorrec...

  2. AP Music Theory Applied

    Science.gov (United States)

    Spieker, Matthew H.

    2016-01-01

    Some American high schools include Advanced Placement (AP) Music Theory within their course offerings. Students who pass the AP exam can receive college credit either as a music or humanities credit. An AP class, however, offers music students more than future college credit; it ultimately improves musicianship skills and promotes deeper…

  3. Atividades de quitinase e beta-1,3-glucanase após eliciação das defesas do tomateiro contra a mancha-bacteriana Chitinase and beta-1,3-glucanase activities after the elicitation of tomato defenses against bacterial spot

    Directory of Open Access Journals (Sweden)

    Fábio Rossi Cavalcanti

    2006-12-01

    Full Text Available O objetivo deste trabalho foi avaliar a influência de eliciadores biológicos e químicos sobre as atividades de duas proteínas relacionadas à patogênese (PR, quitinase e beta-1,3-glucanase, em folhas de tomateiro, e avaliar o potencial desses eliciadores na redução do progresso da mancha-foliar causada por Xanthomonas campestris pv. vesicatoria. Plantas de tomateiro da cultivar Santa Cruz Kada foram pulverizadas com: acibenzolar-S-metil (ASM; 0,2 g L-1; formulação biológica proveniente de biomassa cítrica, denominada Ecolife (5 mL L-1; suspensão de quitosana (MCp; 200 g L-1, proveniente de micélio de Crinipellis perniciosa; extrato aquoso de ramos de lobeira (Solanum lycocarpum infectados por C. perniciosa (VLA; 300 g L-1. As plantas foram desafiadas com um isolado virulento da bactéria, quatro dias depois das pulverizações. Plantas pulverizadas com extratos biológicos mostraram redução da mancha-bacteriana. ASM proporcionou 49,3% de proteção, e foi igual à MCp e Ecolife e superior ao VLA. Este último não diferiu significativamente de MCp e Ecolife. Observou-se maior atividade das duas enzimas nas plantas tratadas, principalmente nas primeiras horas após as pulverizações.The objective of this work was to assess the influence of foliar application of resistance inducers and the activation of plant pathogenesis-related (PR proteins, chitinases and beta-1,3-glucanases, against Xanthomonas campestris pv. vesicatoria, and evaluate the potential of these elicitors on the reduction of bacterial leaf spot. Tomato plants of the cultivar Santa Cruz Kada were sprayed with: acibenzolar-S-methyl (0.2 g L-1 ASM; Ecolife, a biological formulation based on citric biomass (5 mL L-1; chitosan suspension from Crinipellis perniciosa mycelium (MCp; 200 g L-1; an aqueous extract from branches of lobeira (Solanum lycocarpum infected with C. perniciosa (VLA; 300 g L-1. Plants were challenged with a virulent bacterial strain four days after

  4. The 2003-4 multisite photometric campaign for the Beta Cephei and eclipsing star 16 (EN) Lacertae with an Appendix on 2 Andromedae, the variable comparison star

    CERN Document Server

    Jerzykiewicz, M; Daszynska-Daszkiewicz, J; Pigulski, A; Poretti, E; Rodriguez, E; Amado, P J; Kolaczkowski, Z; Uytterhoeven, K; Dorokhova, T N; Dorokhov, N I; Lorenz, D; Zsuffa, D; Kim, S -L; Bourge, P -O; Acke, B; De Ridder, J; Verhoelst, T; Drummond, R; Movchan, A I; Lee, J -A; Steslicki, M; Molenda-Zakowicz, J; Garrido, R; Kim, S -H; Michalska, G; Paparo, M; Antoci, V; Aerts, C

    2015-01-01

    A multisite photometric campaign for the Beta Cephei and eclipsing variable 16 Lacertae is reported. 749 h of high-quality differential photoelectric Stromgren, Johnson and Geneva time-series photometry were obtained with ten telescopes during 185 nights. After removing the pulsation contribution, an attempt was made to solve the resulting eclipse light curve by means of the computer program EBOP. Although a unique solution was not obtained, the range of solutions could be constrained by comparing computed positions of the secondary component in the Hertzsprung-Russell diagram with evolutionary tracks. For three high-amplitude pulsation modes, the uvy and the Geneva UBG amplitude ratios are derived and compared with the theoretical ones for spherical-harmonic degrees l <= 4. The highest degree, l = 4, is shown to be incompatible with the observations. One mode is found to be radial, one is l = 1, while in the remaining case l = 2 or 3. The present multisite observations are combined with the archival photo...

  5. Measurement of amplitude detuning at flat-top and beta star = 0.6 m using AC dipoles

    CERN Document Server

    Bach, T; Langner, A; Levinsen, Z I; Miyamoto, R; Maclean, E H; McAteer, M J; Redaelli, R; Skowronski, P K; Tomas, R; Persson, T H B; White, S

    2013-01-01

    This paper reports on the first direct measurement of amplitude detuning using AC dipoles. The only means in the LHC at high energy to excite large betatron oscillations is using AC dipoles. In the linear regime a perfect AC dipole does not excite the natural tune of the machine. This seriously challenges the measurement of the amplitude detuning by having to rely on imperfections in order to observe the natural tune. The measurements were carried out at $\\beta$*=0.6 m and at flat-top during two MD sessions in 12-10-2012 and 27-11-2012, respectively.

  6. Sparse aperture masking at the VLT II. Detection limits for the eight debris disks stars $\\beta$ Pic, AU Mic, 49 Cet, $\\eta$ Tel, Fomalhaut, g Lup, HD181327 and HR8799

    CERN Document Server

    Gauchet, L; Lagrange, A -M; Ehrenreich, D; Bonnefoy, M; Girard, J H; Boccaletti, A

    2016-01-01

    Context. The formation of planetary systems is a common, yet complex mechanism. Numerous stars have been identified to possess a debris disk, a proto-planetary disk or a planetary system. The understanding of such formation process requires the study of debris disks. These targets are substantial and particularly suitable for optical and infrared observations. Sparse Aperture masking (SAM) is a high angular resolution technique strongly contributing to probe the region from 30 to 200 mas around the stars. This area is usually unreachable with classical imaging, and the technique also remains highly competitive compared to vortex coronagraphy. Aims. We aim to study debris disks with aperture masking to probe the close environment of the stars. Our goal is either to find low mass companions, or to set detection limits. Methods. We observed eight stars presenting debris disks ( $\\beta$ Pictoris, AU Microscopii, 49 Ceti, $\\eta$ Telescopii, Fomalhaut, g Lupi, HD181327 and HR8799) with SAM technique on the NaCo ins...

  7. The IRX-beta relation on sub-galactic scales in star-forming galaxies of the Herschel Reference Survey

    CERN Document Server

    Boquien, M; Boselli, A; Baes, M; Bendo, G J; Ciesla, L; Cooray, A; Cortese, L; Eales, S; Gavazzi, G; Gomez, H L; Lebouteiller, V; Pappalardo, C; Pohlen, M; Smith, M W L; Spinoglio, L

    2012-01-01

    UV and optical surveys are essential to gain insight into the processes driving galaxy formation and evolution. The rest-frame UV emission is key to measure the cosmic SFR. However, UV light is strongly reddened by dust. In starburst galaxies, the UV colour and the attenuation are linked, allowing to correct for dust extinction. Unfortunately, evidence has been accumulating that the relation between UV colour and attenuation is different for normal star-forming galaxies when compared to starburst galaxies. It is still not understood why star-forming galaxies deviate from the UV colour-attenuation relation of starburst galaxies. Previous work and models hint that the role of the shape of the attenuation curve and the age of stellar populations have an important role. In this paper we aim at understanding the fundamental reasons to explain this deviation. We have used the CIGALE SED fitting code to model the far UV to the far IR emission of a set of 7 reasonably face-on spiral galaxies from the HRS. We have exp...

  8. Advanced Photon Source (APS)

    Data.gov (United States)

    Federal Laboratory Consortium — The Advanced Photon Source (APS) at the U.S. Department of Energy's Argonne National Laboratoryprovides this nation's (in fact, this hemisphere's) brightest storage...

  9. APS and Open Access

    Science.gov (United States)

    2011-03-01

    The movement toward Open Access continues to gain momentum. A brief review of APS efforts in this area will be presented by APS Editor in Chief, Gene Sprouse. Editors from Physical Review A, B, E, Focus, Letters, and X, Reviews of Modern Physics, and Physics will address your questions about publishing in this evolving environment.

  10. Gas and dust in the star-forming region rho Oph A: The dust opacity exponent beta and the gas-to-dust mass ratio g2d

    CERN Document Server

    Liseau, R; Lunttila, T; Olberg, M; Rydbeck, G; Bergman, P; Justtanont, K; Olofsson, G; de Vries, B L

    2015-01-01

    We aim at determining the spatial distribution of the gas and dust in star-forming regions and address their relative abundances in quantitative terms. We also examine the dust opacity exponent beta for spatial and/or temporal variations. Using mapping observations of the very dense rho Oph A core, we examined standard 1D and non-standard 3D methods to analyse data of far-infrared and submillimeter (submm) continuum radiation. The resulting dust surface density distribution can be compared to that of the gas. The latter was derived from the analysis of accompanying molecular line emission, observed with Herschel from space and with APEX from the ground. As a gas tracer we used N2H+, which is believed to be much less sensitive to freeze-out than CO and its isotopologues. Radiative transfer modelling of the N2H+(J=3-2) and (J=6-5) lines with their hyperfine structure explicitly taken into account provides solutions for the spatial distribution of the column density N(H2), hence the surface density distribution ...

  11. Asteroseismology of the Beta Cephei star Nu Eridani -- IV. The 2003-4 multisite photometric campaign and the combined 2002-4 data

    CERN Document Server

    Jerzykiewicz, M; Shobbrook, R R; Pigulski, A; Medupe, R; Mokgwetsi, T; Tlhagwane, P; Rodríguez, E

    2005-01-01

    The second multisite photometric campaign devoted to Nu Eri is reported. For Nu Eri, analysis of the new data adds four independent frequencies to the nine derived previously from the 2002-3 data, three in the range from 7.20 to 7.93 c/d, and a low one, equal to 0.614 c/d. Combining the new and the old data results in two further independent frequencies, equal to 6.7322 and 6.2236 c/d. Altogether, the oscillation spectrum is shown to consist of 12 high frequencies and two low ones. The latter have u amplitudes about twice as large as the v and y amplitudes, a signature of high radial-order g modes. Thus, the suggestion that Nu Eri is both a Beta Cephei and an SPB star, put forward on the basis of the first campaign's data, is confirmed. Nine of the 12 high frequencies form three triplets, of which two are new. The triplets represent rotationally split l=1 modes, although in case of the smallest-amplitude one this may be questioned. Mean separations and asymmetries of the triplets are derived with accuracy suf...

  12. 15-Deoxy-delta12,14-PGJ2, but not troglitazone, modulates IL-1beta effects in human chondrocytes by inhibiting NF-kappaB and AP-1 activation pathways.

    Science.gov (United States)

    Boyault, S; Simonin, M A; Bianchi, A; Compe, E; Liagre, B; Mainard, D; Bécuwe, P; Dauça, M; Netter, P; Terlain, B; Bordji, K

    2001-07-13

    The activation of peroxisome proliferator-activated receptor gamma (PPARgamma) has been shown to inhibit the production and the effects of proinflammatory cytokines. Since interleukin-1beta (IL-1beta) directly mediates cartilage degradation in osteoarthritis, we investigated the capability of PPARgamma ligands to modulate IL-1beta effects on human chondrocytes. RT-PCR and Western blot analysis revealed that PPARgamma expression was decreased by IL-1beta. 15-deoxy-Delta12,14-prostaglandin J2 (15d-PGJ2), in contrast to troglitazone, was highly potent to counteract IL-1beta-induced cyclooxygenase-2 and inductible nitric oxide synthase expression, NO production and the decrease in proteoglycan synthesis. Western blot and gel-shift analyses demonstrated that 15d-PGJ2 inhibited NF-kappaB activation, while troglitazone was ineffective. Although 15d-PGJ2 attenuated activator protein-1 binding on the DNA, it potentiated c-jun migration in the nucleus. The absence or the low effect of troglitazone suggests that 15d-PGJ2 action in human chondrocytes is mainly PPARgamma-independent.

  13. APS Science 2006.

    Energy Technology Data Exchange (ETDEWEB)

    Gibson, J. M.; Fenner, R. B.; Long, G.; Borland, M.; Decker, G.

    2007-05-24

    In my five years as the Director of the Advanced Photon Source (APS), I have been fortunate to see major growth in the scientific impact from the APS. This year I am particularly enthusiastic about prospects for our longer-term future. Every scientific instrument must remain at the cutting edge to flourish. Our plans for the next generation of APS--an APS upgrade--got seriously in gear this year with strong encouragement from our users and sponsors. The most promising avenue that has emerged is the energy-recovery linac (ERL) (see article on page xx), for which we are beginning serious R&D. The ERL{at}APS would offer revolutionary performance, especially for x-ray imaging and ultrafast science, while not seriously disrupting the existing user base. I am very proud of our accelerator physics and engineering staff, who not only keep the current APS at the forefront, but were able to greatly impress our international Machine Advisory Committee with the quality of their work on the possible upgrade option (see page xx). As we prepare for long-term major upgrades, our plans to develop and optimize all the sectors at APS in the near future are advancing. Several new beamlines saw first light this year, including a dedicated powder diffraction beamline (11-BM), two instruments for inelastic x-ray scattering at sector 30, and the Center for Nanoscale Materials (CNM) Nanoprobe beamline at sector 26. Our partnership in the first x-ray free-electron laser (LCLS) to be built at Stanford contributes to revolutionary growth in ultrafast science (see page xx), and we are developing a pulse chirping scheme to get ps pulses at sector 7 of the APS within a year or so. In this report, you will find selected highlights of scientific research at the APS from calendar year 2006. The highlighted work covers diverse disciplines, from fundamental to applied science. In the article on page xx you can see the direct impact of APS research on technology. Several new products have emerged from

  14. AP statistics crash course

    CERN Document Server

    D'Alessio, Michael

    2012-01-01

    AP Statistics Crash Course - Gets You a Higher Advanced Placement Score in Less Time Crash Course is perfect for the time-crunched student, the last-minute studier, or anyone who wants a refresher on the subject. AP Statistics Crash Course gives you: Targeted, Focused Review - Study Only What You Need to Know Crash Course is based on an in-depth analysis of the AP Statistics course description outline and actual Advanced Placement test questions. It covers only the information tested on the exam, so you can make the most of your valuable study time. Our easy-to-read format covers: exploring da

  15. APS Science 2009.

    Energy Technology Data Exchange (ETDEWEB)

    Gibson, J. M; Mills, D. M.; Gerig, R.

    2010-05-01

    It is my pleasure to introduce the 2009 annual report of the Advanced Photon Source. This was a very good year for us. We operated with high reliability and availability, despite growing problems with obsolete systems, and our users produced a record output of publications. The number of user experiments increased by 14% from 2008 to more than 3600. We congratulate the recipients of the 2009 Nobel Prize in Chemistry-Venkatraman Ramakrishnan (Cambridge Institute for Medical Research), Thomas Steitz (Yale University), and Ada Yonath (Weizmann Institute) - who did a substantial amount of this work at APS beamlines. Thanks to the efforts of our users and staff, and the ongoing counsel of the APS Scientific Advisory Committee, we made major progress in advancing our planning for the upgrade of the APS (APS-U), producing a proposal that was positively reviewed. We hope to get formal approval in 2010 to begin the upgrade. With advocacy from our users and the support of our sponsor, the Office of Basic Energy Sciences in the Department of Energy (DOE) Office of Science, our operating budgets have grown to the level needed to more adequately staff our beamlines. We were also extremely fortunate to have received $7.9 M in American Recovery and Reinvestment Act ('stimulus') funding to acquire new detectors and improve several of our beamlines. The success of the new Linac Coherent Light Source at Stanford, the world's first x-ray free-electron laser, made us particularly proud since the undulators were designed and built by the APS. Among other highlights, we note that more than one-quarter of the 46 Energy Frontier Research Centers, funded competitively across the U.S. in 2009 by the DOE, included the Advanced Photon Source in their proposed work, which shows that synchrotron radiation, and the APS in particular, are central to energy research. While APS research covers everything from fundamental to applied science (reflected by the highlights in this report

  16. APS Science 2007.

    Energy Technology Data Exchange (ETDEWEB)

    2008-05-30

    This report provides research highlights from the Advanced Photon Source (APS). Although these highlights represent less than 10% of the published work from the APS in 2007, they give a flavor of the diversity and impact of user research at the facility. In the strategic planning the aim is to foster the growth of existing user communities and foresee new areas of research. This coming year finds the APS engaged in putting together, along with the users, a blueprint for the next five years, and making the case for a set of prioritized investments in beamlines, the accelerator, and infrastructure, each of which will be transformational in terms of scientific impact. As this is written plans are being formulated for an important user workshop on October 20-21, 2008, to prioritize strategic plans. The fruit from past investments can be seen in this report. Examples include the creation of a dedicated beamline for x-ray photon correlation spectroscopy at Sector 8, the evolution of dedicated high-energy x-ray scattering beamlines at sectors 1 and 11, a dedicated imaging beamline at Sector 32, and new beamlines for inelastic scattering and powder diffraction. A single-pulse facility has been built in collaboration with Sector 14 (BioCARS) and Phil Anfinrud at the National Institutes of Health, which will offer exceptionally high flux for single-pulse diffraction. The nanoprobe at Sector 26, built and operated jointly by the Argonne Center for Nanoscale Materials and the X-ray Operations and Research (XOR) section of the APS X-ray Science Division, has come on line to define the state of the art in nanoscience.

  17. Coroutine Sequencing in BETA

    DEFF Research Database (Denmark)

    Kristensen, Bent Bruun; Madsen, Ole Lehrmann; Møller-Pedersen, Birger;

    In object-oriented programming, a program execution is viewed as a physical model of some real or imaginary part of the world. A language supporting object-oriented programming must therefore contain comprehensive facilities for modeling phenomena and concepts form the application domain. Many ap...... applications in the real world consist of objects carrying out sequential processes. Coroutines may be used for modeling objects that alternate between a number of sequential processes. The authors describe coroutines in BETA...

  18. The APS ceramic chambers

    Energy Technology Data Exchange (ETDEWEB)

    Milton, S.; Warner, D.

    1994-07-01

    Ceramics chambers are used in the Advanced Photon Source (APS) machines at the locations of the pulsed kicker and bumper magnets. The ceramic will be coated internally with a resistive paste. The resistance is chosen to allow the low frequency pulsed magnet field to penetrate but not the high frequency components of the circulating beam. Another design goal was to keep the power density experienced by the resistive coating to a minimum. These ceramics, their associated hardware, the coating process, and our recent experiences with them are described.

  19. Quantitative assessment of lumber facet joints and intervertebral discs with axial MR T 2 star mapping%轴位 MRT2*m apping 对腰椎小关节和椎间盘的定量研究

    Institute of Scientific and Technical Information of China (English)

    曹观美; 赵斌

    2014-01-01

    目的:探讨轴位腰椎小关节和椎间盘M R T2*mapping成像的可行性,明确T2*mapping定量成像技术对小关节和椎间盘早期退变的评估价值。方法收集慢性下腰痛患者22名作为病例组,性别和年龄匹配的健康志愿者20名为正常对照组,采用3.0T M RI对两组行T2*mapping及常规T2 WI成像,根据Weishaupt分级法、Pfirrmann分级法分别对L2~ S1各节段小关节和椎间盘进行形态学分级,并测量小关节和椎间盘的 T2*值,进行对比分析。结果不同Weishaupt分级小关节的T2*值差异无统计学意义( P>0.05)。不同Pfirrmann分级椎间盘髓核的T2*值差异有统计学意义( P <0.05)。小关节与后纤维环的T 2*值呈弱相关性( r‐0.3874)。病例组与对照组小关节的 T 2*值很相近,而髓核的T2*值差异有统计学意义( P <0.05)。在小关节评价的组间一致性方面,T2*值的一致性很好( r =0.835,P <0.05);形态学Weishaupt分级一致性较差(kappa=0.327)。结论此研究表明T2* mapping可用于软骨的定量研究,且轴位的腰椎小关节和椎间盘T2*mapping联合成像是可行的。%Objective To value the feasibility of MR T2 star mapping of lumbar facet joints and intervertebral discs ,and to evaluate the diagnostic value of T 2 star mapping in early‐stage degeneration of lumbar facet joints and intervertebral discs .Methods 22 patients with low back pain and 20 age‐and sex‐matched volunteers were examined .T2 star mapping and fast spin echo T2WI of lumber facet joints and intervertebral discs were evaluated with a 3 .0 T MR imaging spectrom‐eter in 42 subjects .The Weishaupt grading was used for L2 ~S1 facet joints and the pfirrmann score was used for morpho‐logical disc grading .T2 star value in the facet joints and the intervertebral discs were measured respectively in T 2 star map‐ping imaging ,and the correlation of them and variance in

  20. A Low-Resolution Spectroscopic Exploration of Puzzling OGLE Variable Stars

    CERN Document Server

    Pietrukowicz, P; Angeloni, R; di Mille, F; Soszynski, I; Udalski, A; Germana, C

    2015-01-01

    We present the results of a spectroscopic follow-up of various puzzling variable objects detected in the OGLE-III Galactic disk and bulge fields. The sample includes mainly short-period multi-mode pulsating stars that could not have been unambiguously classified as either delta Sct or beta Cep type stars based on photometric data only, also stars with irregular fluctuations mimicking cataclysmic variables and stars with dusty shells, and periodic variables displaying brightenings in their light curves that last for more than half of the period. The obtained low-resolution spectra show that all observed short-period pulsators are of delta Sct type, the stars with irregular fluctuations are young stellar objects, and the objects with regular brightenings are A type stars or very likely Ap stars with strong magnetic field responsible for the presence of bright caps around magnetic poles on their surface. We also took spectra of objects designated OGLE-GD-DSCT-0058 and OGLE-GD-CEP-0013. An estimated effective tem...

  1. Beta Thalassemia

    Science.gov (United States)

    Beta thalassemia is found in people of Mediterranean, Middle Eastern, African, South Asian (Indian, Pakistani, etc.), Southeast Asian and Chinese descent. 1 Beta Thalassemia ßß Normal beta globin genes found on chromosomes ...

  2. CGM ApS Årsberetning til DANAK

    DEFF Research Database (Denmark)

    De Chiffre, Leonardo

    Denne årsberetning omfatter CGM ApS' akkrediterede virksomhed i kalenderåret 2003. Årsberetningen er udarbejdet til DANAK (Dansk Akkreditering, ErhvervsfremmeStyrelsen), som led i opfyldelsen af laboratoriets informationspligt i henhold til gældende regler.......Denne årsberetning omfatter CGM ApS' akkrediterede virksomhed i kalenderåret 2003. Årsberetningen er udarbejdet til DANAK (Dansk Akkreditering, ErhvervsfremmeStyrelsen), som led i opfyldelsen af laboratoriets informationspligt i henhold til gældende regler....

  3. AP physics B crash course

    CERN Document Server

    Howell, Rebecca

    2012-01-01

    AP Physics B Crash Course - Get a Higher Advanced Placement Score in Less Time Crash Course is perfect for the time-crunched student, the last-minute studier, or anyone who wants a refresher on the subject. Our AP Physics B Crash Course gives you: Targeted, Focused Review - Study Only What You Need to Know The Crash Course is based on an in-depth analysis of the AP Physics B course description outline and actual AP test questions. It covers only the information tested on the exam, so you can make the most of your valuable study time. Our easy-to-read format covers: mechanics, kinetic theory, t

  4. Center for Geometrisk Metrologi, CGM ApS

    DEFF Research Database (Denmark)

    De Chiffre, Leonardo

    Denne årsberetning omfatter CGM ApS' akkrediterede virksomhed i kalenderåret 2002. Årsberetningen er udarbejdet til DANAK (Dansk Akkreditering, Erhvervsfremme Styrelsen), som led i opfyldelsen af laboratoriets informationspligt i henhold til gældende regler (Teknisk Forskrift Nr. TF4 af 2000...

  5. Mean-field study of hot beta-stable protoneutron star matter: Impact of the symmetry energy and nucleon effective mass

    CERN Document Server

    Tan, Ngo Hai; Khoa, Dao T; Margueron, Jerome

    2016-01-01

    A consistent Hartree-Fock study of the equation of state (EOS) of asymmetric nuclear matter at finite temperature has been performed using realistic choices of the effective, density dependent nucleon-nucleon (NN) interaction, which were successfully used in different nuclear structure and reaction studies. Given the importance of the nuclear symmetry energy in the neutron star formation, EOS's associated with different behaviors of the symmetry energy were used to study hot asymmetric nuclear matter. The slope of the symmetry energy and nucleon effective mass with increasing baryon density was found to affect the thermal properties of nuclear matter significantly. Different density dependent NN interactions were further used to study the EOS of hot protoneutron star (PNS) matter of the $npe\\mu\

  6. Measurement of sextupole orbit offsets in the APS storage ring.

    Energy Technology Data Exchange (ETDEWEB)

    Borland, M.

    1999-04-16

    Horizontal orbit errors at the sextuples in the Advanced Photon Source (APS) storage ring can cause changes in tune and modulation of the beta functions around the ring. To determine the significance of these effects requires knowing the orbit relative to the magnetic center of the sextuples. The method considered here to determine the horizontal beam position in a given sextupole is to measure the tune shift caused by a change in the sextupole strength. The tune shift and a beta function for the same plane uniquely determine the horizontal beam position in the sextupole. The beta function at the sextupole was determined by propagating the beta functions measured at nearby quadrupoles to the sextupole location. This method was used to measure the sextupole magnetic center offset relative to an adjacent beam position monitor (BPM) at a number of sextupole locations. We report on the successes and problems of the method as well as an improved method.

  7. Learning about Antiphospholipid Syndrome (APS)

    Science.gov (United States)

    ... other autoimmune disorders, including myasthenia gravis, Graves' disease, autoimmune hemolytic anemia, and Evan's syndrome. Top of page How is APS diagnosed? A diagnosis of APS is made based on both clinical and ... Autoimmune Related Diseases Association, Inc. [aarda.org] An organization ...

  8. Heterologous expression of ApGSMT2 and ApDMT2 genes from Aphanothece halophytica enhanced drought tolerance in transgenic tobacco.

    Science.gov (United States)

    He, Ying; He, Chunmei; Li, Lihua; Liu, Zhili; Yang, Aifang; Zhang, Juren

    2011-01-01

    The glycine-methylation biosynthetic pathway of glycinebetaine (GB) has been investigated, but only a few studies on GB accumulation in transgenic higher plants have utilized this pathway. In this study, two methyltransferase genes named ApGSMT2 and ApDMT2, encoding proteins catalyzing GB biosynthesis from glycine, were cloned from a relative strain of Aphanothece halophytica. The potential roles of ApGSMT2 and ApDMT2 in GB synthesis were first examined in transgenic Escherichia coli, which had increased levels of GB and improved salt tolerance. Then ApGSMT2 and ApDMT2 were transferred into tobacco. Compared with transgenic tobacco expressing betA, transgenic tobacco co-expressing ApGSMT2 and ApDMT2 accumulated more GB and exhibited enhanced drought resistance with better germination performance, higher relative water content, less cell membrane damage and better photosynthetic capacity under drought stress. We concluded that the ApGSMT2 and ApDMT2 genes cloned in this study will be very useful for engineering GB-accumulating transgenic plants with enhanced drought resistance.

  9. APS Editorial Q&A: APS and Open Access

    Science.gov (United States)

    2011-04-01

    The movement toward Open Access continues to gain momentum. A brief review of APS efforts in this area will be presented by APS Editor in Chief, Gene Sprouse. Editors from Physical Review C, D, Letters, and X, Physical Review Special Topics - Accelerators and Beams, Physical Review Special Topics - Physics Education Research, and Reviews of Modern Physics will address your questions about publishing in this evolving environment.

  10. Task Force on Catastrophic Antiphospholipid Syndrome (APS) and Non-criteria APS Manifestations (I): catastrophic APS, APS nephropathy and heart valve lesions.

    Science.gov (United States)

    Cervera, R; Tektonidou, M G; Espinosa, G; Cabral, A R; González, E B; Erkan, D; Vadya, S; Adrogué, H E; Solomon, M; Zandman-Goddard, G; Shoenfeld, Y

    2011-02-01

    The objectives of the 'Task Force on Catastrophic Antiphospholipid Syndrome (APS) and Non-criteria APS Manifestations' were to assess the clinical utility of the international consensus statement on classification criteria and treatment guidelines for the catastrophic APS, to identify and grade the studies that analyse the relationship between the antiphospholipid antibodies and the non-criteria APS manifestations and to present the current evidence regarding the accuracy of these non-criteria APS manifestations for the detection of patients with APS. This article summarizes the studies analysed on the catastrophic APS, APS nephropathy and heart valve lesions, and presents the recommendations elaborated by the Task Force after this analysis.

  11. [Apheresis in antiphospholipid syndrome (APS)].

    Science.gov (United States)

    De Silvestro, Giustina; Tison, Tiziana; Marson, Piero

    2012-01-01

    Antiphospholipid syndrome (APS) is a rare clinical disorder characterized by thromboembolic manifestations and/or obstetric complications. Along with the clinical symptoms and signs, serum antiphospholipid antibodies have to be detected. APS can be primary, i.e., without any concomitant disorders, or secondary to other autoimmune diseases, particularly systemic lupus erythematosus. Criteria for the diagnosis of APS have been clearly established. Hyperacute APS (or catastrophic antiphospholipid syndrome), often with a poor prognosis, must meet four criteria: involvement of three or more organs, rapid evolution of clinical manifestations, microangiopathic occlusion of small blood vessels at biopsy, and presence of antiphospholipid antibodies. The rationale for apheresis treatment is the removal of pathogenetic antibodies involved in the development of tissue damage. Our experience includes 23 patients, in particular 15 women treated for 19 pregnancies. According to the National Guidelines Program, the effectiveness of apheresis in catastrophic syndrome has a level of evidence of V/VI, with a strength of recommendation A; in highrisk pregnancy it has a level of evidence of V with a strength of recommendation B. It will be necessary to better define the prognosis of various categories of pregnant patients with APS, as well as useful laboratory parameters to monitor its clinical course and anticipate any complications of pregnancy.

  12. APS Education and Diversity Efforts

    Science.gov (United States)

    Prestridge, Katherine; Hodapp, Theodore

    2015-11-01

    American Physical Society (APS) has a wide range of education and diversity programs and activities, including programs that improve physics education, increase diversity, provide outreach to the public, and impact public policy. We present the latest programs spearheaded by the Committee on the Status of Women in Physics (CSWP), with highlights from other diversity and education efforts. The CSWP is working to increase the fraction of women in physics, understand and implement solutions for gender-specific issues, enhance professional development opportunities for women in physics, and remedy issues that impact gender inequality in physics. The Conferences for Undergraduate Women in Physics, Professional Skills Development Workshops, and our new Professional Skills program for students and postdocs are all working towards meeting these goals. The CSWP also has site visit and conversation visit programs, where department chairs request that the APS assess the climate for women in their departments or facilitate climate discussions. APS also has two significant programs to increase participation by underrepresented minorities (URM). The newest program, the APS National Mentoring Community, is working to provide mentoring to URM undergraduates, and the APS Bridge Program is an established effort that is dramatically increasing the number of URM PhDs in physics.

  13. Study of the Cygnus Star-Forming Field

    Science.gov (United States)

    Christopherson, Christopher; Kaltcheva, Nadia

    2016-01-01

    The star-forming complexes in Cygnus extend nearly 30 deg in Galactic longitude and 20 deg in latitude, and most probably include star-formation sites located between 600 and 4000 pc. We combine the catalog by Heiles (2000) with uvbyβ photometric data from the catalog of Paunzen (2015) to collate a sample of O and B-type stars with precise homogeneous distances, color excess and available polarimetry. This allows us to identify star-forming sites at different distances along the line of sight and to investigate their spatial correlation to the interstellar matter. Further, we use this sample to study the orientation of the polarization as revealed by the polarized light of the bright early-type stars and analyze the polarization-extinction correlation for this field. Since dust grains align in the presence of a magnetic field cause the observed polarization at optical wavelengths, the data contain information about the large-scale component of the Galactic magnetic field. In addition, wide-field astrophotography equipment was used to image the Cygnus field in Hydrogen-alpha, Hydrogen-beta and the [OIII] line at 500.7 nm. This allows us to map the overall distribution of ionized material and the interstellar dust and trace large-scale regions where the physical conditions change rapidly due to supernova shock fronts and strong stellar winds. Acknowledgments: This work was supported by NSF grant AST- 1516932 and the Wisconsin Space Grant Consortium, NASA Space Grant College and Fellowship Program, NASA Training Grant #NNX14AP22H.

  14. Structural characterization of the N-terminal mineral modification domains from the molluscan crystal-modulating biomineralization proteins, AP7 and AP24.

    Science.gov (United States)

    Wustman, Brandon A; Morse, Daniel E; Evans, John Spencer

    2004-08-05

    The AP7 and AP24 proteins represent a class of mineral-interaction polypeptides that are found in the aragonite-containing nacre layer of mollusk shell (H. rufescens). These proteins have been shown to preferentially interfere with calcium carbonate mineral growth in vitro. It is believed that both proteins play an important role in aragonite polymorph selection in the mollusk shell. Previously, we demonstrated the 1-30 amino acid (AA) N-terminal sequences of AP7 and AP24 represent mineral interaction/modification domains in both proteins, as evidenced by their ability to frustrate calcium carbonate crystal growth at step edge regions. In this present report, using free N-terminal, C(alpha)-amide "capped" synthetic polypeptides representing the 1-30 AA regions of AP7 (AP7-1 polypeptide) and AP24 (AP24-1 polypeptide) and NMR spectroscopy, we confirm that both N-terminal sequences possess putative Ca (II) interaction polyanionic sequence regions (2 x -DD- in AP7-1, -DDDED- in AP24-1) that are random coil-like in structure. However, with regard to the remaining sequences regions, each polypeptide features unique structural differences. AP7-1 possesses an extended beta-strand or polyproline type II-like structure within the A11-M10, S12-V13, and S28-I27 sequence regions, with the remaining sequence regions adopting a random-coil-like structure, a trait common to other polyelectrolyte mineral-associated polypeptide sequences. Conversely, AP24-1 possesses random coil-like structure within A1-S9 and Q14-N16 sequence regions, and evidence for turn-like, bend, or loop conformation within the G10-N13, Q17-N24, and M29-F30 sequence regions, similar to the structures identified within the putative elastomeric proteins Lustrin A and sea urchin spicule matrix proteins. The similarities and differences in AP7 and AP24 N-terminal domain structure are discussed with regard to joint AP7-AP24 protein modification of calcium carbonate growth.

  15. VizieR Online Data Catalog: New photometrically variable magnetic CP stars (Hummerich+, 2016)

    Science.gov (United States)

    Hummerich, S.; Paunzen, E.; Bernhard, K.

    2016-10-01

    The All Sky Automated Survey (ASAS) constantly monitored the entire southern sky and part of the northern sky to about δCP2 stars or CP2 star (the magnetic Bp/Ap stars) candidates and He-weak (CP4)/He-strong objects from the most recent version of the Catalog of Ap, HgMn, and Am stars (Renson & Manfroid 2009, Cat. III/260). (2 data files).

  16. AP Geography, Environmental Science Thrive

    Science.gov (United States)

    Robelen, Erik W.

    2012-01-01

    Geography may not be particularly known as a hot topic among today's students--even some advocates suggest it suffers from an image problem--but by at least one measure, the subject is starting to come into its own. Across more than 30 topics covered in the Advanced Placement (AP) program, participation in geography is rising faster than any…

  17. The Classificiation of Kepler B star Variables

    CERN Document Server

    McNamara, Bernard J; McKeever, Jean

    2012-01-01

    The light curves of 252 B-star candidates in the Kepler data base are analyzed in a similar fashion to that done by Balona et al. (2011) to further characterize B star variability, increase the sample of variable B stars for future study, and to identify stars whose power spectra include particularly interesting features such as frequency groupings. Stars are classified as either constant light emitters, $\\beta$ Cep stars, slowly pulsating B stars, hybrid pulsators, binaries or stars whose light curves are dominated by rotation (Bin/Rot), hot subdwarfs, or white dwarfs. One-hundred stars in our sample were found to be either light contants or to be variable at a level of less than 0.02 mmag. We increase the number of candidate B-star variables found in the Kepler data base by Balona et al. (2011) in the following fashion: $\\beta$ Cep stars from 0 to 10, slowly pulsating B stars from 8 to 54, hybrid pulsators from 7 to 21, and Bin/Rot stars from 23 to 82. For comparison purposes, approximately 51 SPBs and 6 hy...

  18. Structural Determinants of DNA Binding by a P. falciparum ApiAP2 Transcriptional Regulator

    Energy Technology Data Exchange (ETDEWEB)

    Lindner, Scott E.; De Silva, Erandi K.; Keck, James L.; Llinás, Manuel (Princeton); (UW-MED)

    2010-11-05

    Putative transcription factors have only recently been identified in the Plasmodium spp., with the major family of regulators comprising the Apicomplexan Apetala2 (AP2) proteins. To better understand the DNA-binding mechanisms of these transcriptional regulators, we characterized the structure and in vitro function of an AP2 DNA-binding domain from a prototypical Apicomplexan AP2 protein, PF14{_}0633 from Plasmodium falciparum. The X-ray crystal structure of the PF14{_}0633 AP2 domain bound to DNA reveals a {beta}-sheet fold that binds the DNA major groove through base-specific and backbone contacts; a prominent {alpha}-helix supports the {beta}-sheet structure. Substitution of predicted DNA-binding residues with alanine weakened or eliminated DNA binding in solution. In contrast to plant AP2 domains, the PF14{_}0633 AP2 domain dimerizes upon binding to DNA through a domain-swapping mechanism in which the {alpha}-helices of the AP2 domains pack against the {beta}-sheets of the dimer mates. DNA-induced dimerization of PF14{_}0633 may be important for tethering two distal DNA loci together in the nucleus and/or for inducing functional rearrangements of its domains to facilitate transcriptional regulation. Consistent with a multisite binding mode, at least two copies of the consensus sequence recognized by PF14{_}0633 are present upstream of a previously identified group of sporozoite-stage genes. Taken together, these findings illustrate how Plasmodium has adapted the AP2 DNA-binding domain for genome-wide transcriptional regulation.

  19. uvbybeta photometry of early type open cluster and field stars

    CERN Document Server

    Handler, G

    2011-01-01

    The beta Cephei stars and slowly pulsating B (SPB) stars are massive main sequence variables. The strength of their pulsational driving strongly depends on the opacity of iron-group elements. As many of those stars naturally occur in young open clusters, whose metallicities can be determined in several fundamental ways, it is logical to study the incidence of pulsation in several young open clusters. To provide the foundation for such an investigation, Str\\"omgren-Crawford uvbybeta photometry of open cluster target stars was carried out to determine effective temperatures, luminosities, and therefore cluster memberships. In the course of three observing runs, uvbybeta photometry for 168 target stars was acquired and transformed into the standard system by measurements of 117 standard stars. The list of target stars also included some known cluster and field beta Cephei stars, as well as beta Cephei and SPB candidates that are targets of the asteroseismic part of the Kepler satellite mission. The uvbybeta phot...

  20. Producing Runaway Stars

    Science.gov (United States)

    Kohler, Susanna

    2016-07-01

    LMC. When this speed is combined with the orbital velocity of the LMC itself (another ~380 km/s relative to the Milky Way), this could result in hypervelocity stars moving faster than the escape speed of the Milky Way, as observed.Predicted distribution of hypervelocity stars ejected from the LMC, in galactic coordinates. The red crosses show locations of detected hypervelocity stars, and the green arrow marks the path of the LMC over the last 350 million years. [Boubert Evans 2016]If the LMC is indeed ejecting hypervelocity stars along its orbit, this could explain an observed anisotropy in the hypervelocity stars weve detected, with many of these stars clustering in the constellations of Leo and Sextans. This clustering is consistent with stars ejected ahead of the LMCs orbit.How can we test this model for the production of hypervelocity stars? The authors model predicts the presence of a significant number of hypervelocity stars near the LMC in the southern hemisphere, a region which has been poorly surveyed before now. Surveys such as SkyMapper and Gaia, however, will observe this region and their discoveries (or lack thereof) should provide a useful test of whether hypervelocity stars are accelerated by the LMC.CitationDouglas Boubert and N. Wyn Evans 2016 ApJ 825 L6. doi:10.3847/2041-8205/825/1/L6

  1. A BRITE view on delta Scuti and gamma Doradus stars

    CERN Document Server

    Zwintz, Konstanze

    2016-01-01

    BRITE-Constellation has obtained data for a few delta Scuti and gamma Doradus type stars. A short overview of the pulsational content found in five stars - beta Cassiopeiae, epsilon Cephei, M Velorum, beta Pictoris and QW Puppis - is given and the potential of BRITE-Constellation observations of delta Scuti and gamma Doradus pulsators is discussed.

  2. Asteroseismology of Pulsating Stars

    Indian Academy of Sciences (India)

    Santosh Joshi; Yogesh C. Joshi

    2015-03-01

    The success of helioseismology is due to its capability of measuring -mode oscillations in the Sun. This allows us to extract information on the internal structure and rotation of the Sun from the surface to the core. Similarly, asteroseismology is the study of the internal structure of the stars as derived from stellar oscillations. In this review we highlight the progress in the observational asteroseismology, including some basic theoretical aspects. In particular, we discuss our contributions to asteroseismology through the study of chemically peculiar stars under the 'Nainital-Cape Survey' project being conducted at ARIES, Nainital, since 1999. This survey aims to detect new rapidly-pulsating Ap (roAp) stars in the northern hemisphere. We also discuss the contribution of ARIES towards the asteroseismic study of the compact pulsating variables. We comment on the future prospects of our project in the light of the new optical 3.6-m telescope to be installed at Devasthal (ARIES). Finally, we present a preliminary optical design of the high-speed imaging photometers for this telescope.

  3. An AP Calculus Classroom Amusement Park

    Science.gov (United States)

    Ferguson, Sarah

    2016-01-01

    Throughout the school year, AP Calculus teachers strive to teach course content comprehensively and swiftly in an effort to finish all required material before the AP Calculus exam. As early May approaches and the AP Calculus test looms, students and teachers nervously complete lessons, assignments, and assessments to ensure student preparation.…

  4. Knockdown of CDK2AP1 in primary human fibroblasts induces p53 dependent senescence.

    Directory of Open Access Journals (Sweden)

    Khaled N Alsayegh

    Full Text Available Cyclin Dependent Kinase-2 Associated Protein-1 (CDK2AP1 is known to be a tumor suppressor that plays a role in cell cycle regulation by sequestering monomeric CDK2, and targeting it for proteolysis. A reduction of CDK2AP1 expression is considered to be a negative prognostic indicator in patients with oral squamous cell carcinoma and also associated with increased invasion in human gastric cancer tissue. CDK2AP1 overexpression was shown to inhibit growth, reduce invasion and increase apoptosis in prostate cancer cell lines. In this study, we investigated the effect of CDK2AP1 downregulation in primary human dermal fibroblasts. Using a short-hairpin RNA to reduce its expression, we found that knockdown of CDK2AP1 in primary human fibroblasts resulted in reduced proliferation and in the induction of senescence associated beta-galactosidase activity. CDK2AP1 knockdown also resulted in a significant reduction in the percentage of cells in the S phase and an accumulation of cells in the G1 phase of the cell cycle. Immunocytochemical analysis also revealed that the CDK2AP1 knockdown significantly increased the percentage of cells that exhibited γ-H2AX foci, which could indicate presence of DNA damage. CDK2AP1 knockdown also resulted in increased mRNA levels of p53, p21, BAX and PUMA and p53 protein levels. In primary human fibroblasts in which p53 and CDK2AP1 were simultaneously downregulated, there was: (a no increase in senescence associated beta-galactosidase activity, (b decrease in the number of cells in the G1-phase and increase in number of cells in the S-phase of the cell cycle, and (c decrease in the mRNA levels of p21, BAX and PUMA when compared with CDK2AP1 knockdown only fibroblasts. Taken together, this suggests that the observed phenotype is p53 dependent. We also observed a prominent increase in the levels of ARF protein in the CDK2AP1 knockdown cells, which suggests a possible role of ARF in p53 stabilization following CDK2AP1

  5. Star Clusters

    OpenAIRE

    Gieles, M.

    1993-01-01

    Star clusters are observed in almost every galaxy. In this thesis we address several fundamental problems concerning the formation, evolution and disruption of star clusters. From observations of (young) star clusters in the interacting galaxy M51, we found that clusters are formed in complexes of stars and star clusters. These complexes share similar properties with giant molecular clouds, from which they are formed. Many (70%) of the young clusters will not survive the fist 10 Myr, due to t...

  6. Stars and Star Myths.

    Science.gov (United States)

    Eason, Oliver

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

  7. Fellow's Apéro

    CERN Multimedia

    Staff Association

    2017-01-01

    Let's get together, meet each other, exchange experiences and ideas, and share useful information on CERN and the Staff Association. Join us for Fellow's Apéro, organised by the Staff Association on Tuesday 21 February at 16.30 in Restaurant 1. There will be drinks and snacks for everybody! We look forward to seeing you there! Please confirm your participation on Doodle http://doodle.com/poll/skvm7ucm2z78i6bt or alternatively on Facebook https://www.facebook.com/events/1862757017340069/. Your delegates in the Staff Association, Barbora & Jiri

  8. Papel da lipoperoxidação na intensificação da remodelação causada pelo betacaroteno após o infarto Rol de la lipoperoxidación en la intensificación de la remodelación ocasionada por el betacaroteno tras infarto Role of lipoperoxidation in the remodeling intensification induced by beta-carotene after infarction

    Directory of Open Access Journals (Sweden)

    Paula S. Azevedo

    2009-07-01

    Full Text Available FUNDAMENTO: Os mecanismos envolvidos na maior remodelação causada pelo betacaroteno após o infarto são desconhecidos. OBJETIVO: Analisar o papel da lipoperoxidação na remodelação ventricular após o infarto do miocárdio, em ratos suplementados com betacaroteno. MÉTODOS: Ratos foram infartados e distribuídos em dois grupos: C (controle e BC (500mg/kg/dieta. Após seis meses, foram realizados ecocardiograma e avaliação bioquímica. Utilizamos o teste t, com significância de 5%. RESULTADOS: Os animais do grupo BC apresentaram maiores médias das áreas diastólicas (C = 1,57 ± 0,4 mm²/g, BC = 2,09 ± 0,3 mm²/g; p FUNDAMENTO: Los mecanismos implicados en la mayor remodelación ocasionada por betacaroteno tras el infarto son desconocidos. OBJETIVO: Analizar el rol que juega la lipoperoxidación en la remodelación ventricular tras el infarto de miocardio, en ratas suplementadas con betacaroteno. MÉTODOS: Se había inducido a un infarto a las ratas y se las distribuyó en grupos: C (control y BC (500mg/kg/dieta. Tras seis meses, se realizaron ecocardiograma y evaluación bioquímica. Utilizamos la prueba t, con significancia del 5%. RESULTADOS: Los animales del grupo BC presentaron mayores promedios de las áreas diastólicas (C = 1,57 ± 0,4 mm²/g, BC = 2,09 ± 0,3 mm²/g; p BACKGROUND: The mechanisms involved in the biggest remodeling caused by the post-infarct beta-carotene are unknown. OBJECTIVE: To analyze the role of lipoperoxidation in the ventricular remodeling after infarct of the myocardium in rats supplemented with beta-carotene. METHODS: Rats were infarcted and divided into two groups: C (control and BC (500mg/kg/regimen. After six months, echocardiogram and biochemical evaluation were performed. The t test was used, with 5% significance. RESULTS: The animals from BC group presented highest means of the diastolic (C = 1.57 ± 0.4 mm²/g, BC = 2.09 ± 0.3 mm²/g; p < 0.001 and systolic (C = 1.05 ± 0.3 mm²/g, BC = 1.61

  9. Testing of Solar Heated Domestic Hot Water System for Solahart Scandinavia ApS

    DEFF Research Database (Denmark)

    Andersen, Elsa

    1997-01-01

    The solar heating system marketed by Solahart Scandinavia ApS was tested in the Institutes test facility for SDHWsystems. The test results are described in the report.......The solar heating system marketed by Solahart Scandinavia ApS was tested in the Institutes test facility for SDHWsystems. The test results are described in the report....

  10. On the Hipparcos parallaxes of O stars

    Science.gov (United States)

    Schröder, S. E.; Kaper, L.; Lamers, H. J. G. L. M.; Brown, A. G. A.

    2004-12-01

    We compare the absolute visual magnitude of the majority of bright O stars in the sky as predicted from their spectral type with the absolute magnitude calculated from their apparent magnitude and the Hipparcos parallax. We find that many stars appear to be much fainter than expected, up to five magnitudes. We find no evidence for a correlation between magnitude differences and the stellar rotational velocity as suggested for OB stars by Lamers et al. (1997, A&A, 325, L25), whose small sample of stars is partly included in ours. Instead, by means of a simulation we show how these differences arise naturally from the large distances at which O stars are located, and the level of precision of the parallax measurements achieved by Hipparcos. Straightforwardly deriving a distance from the Hipparcos parallax yields reliable results for one or two O stars only. We discuss several types of bias reported in the literature in connection with parallax samples (Lutz-Kelker, Malmquist) and investigate how they affect the O star sample. In addition, we test three absolute magnitude calibrations from the literature (Schmidt-Kaler et al. 1982, Landolt-Börnstein; Howarth & Prinja 1989, ApJS, 69, 527; Vacca et al. 1996, ApJ, 460, 914) and find that they are consistent with the Hipparcos measurements. Although O stars conform nicely to the simulation, we notice that some B stars in the sample of \\citeauthor{La97} have a magnitude difference larger than expected.

  11. C-4 155 nm line in beta Cephei

    Science.gov (United States)

    Fischel, D.

    1972-01-01

    The class of early B variable stars known as beta Cephei stars are characterized by short-period radial velocity and light variations. The coolest stars of this group have an effective temperature of about 20,000 K and the hottest, about 28,000 K. These stars are not related to the classical Cepheids whose temperatures are of the order of 6000 K. The amplitude of the radial velocity variation beta Cephei stars is in the tens of kilometers per second and the light variation is less than 0.2 mag, that is, less than 10 percent. The fastest pulsation interval is 3 hr and the slowest is 6 hr. The prototype beta Cephei has a period of 4 hr 34 min. Ultraviolet observations were taken using OAO 2 to investigate the relationship between the visual and the ultraviolet variations.

  12. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Brorsen, Michael; Frigaard, Peter

    Denne rapport beskriver numeriske beregninger af forskellige flydergeometrier for bølgeenergianlæget Wave Star.......Denne rapport beskriver numeriske beregninger af forskellige flydergeometrier for bølgeenergianlæget Wave Star....

  13. On AP-property of Function Spaces

    Institute of Scientific and Technical Information of China (English)

    SHEN Rong-xin

    2012-01-01

    In this paper,it is discussed the AP-property of function spaces.We prove that for any compact network α for a space X which is closed under finite unions,(1) if Cα(X) is an AP-space and X is paracompact,then X is a Hurewicz space; (2) if Cα (X) is an AP-space which has countable tightness,then Cα(X) is discretely generated.

  14. Massive Stars

    Science.gov (United States)

    Livio, Mario; Villaver, Eva

    2009-11-01

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

  15. Structure in the motions of the fastest halo stars

    NARCIS (Netherlands)

    Fiorentin, PR; Helmi, A; Lattanzi, MG; Spagna, A

    2005-01-01

    We analyzed the catalog published by Beers et al. ( 2000, ApJ, 119, 2866) of 2106 non-kinematically selected metal poor stars in the solar neighborhood, with the goal of quantifying the amount of substructure in the motions of the fastest halo stars. We computed the two-point velocity correlation fu

  16. AP calculus AB & BC crash course

    CERN Document Server

    Rosebush, J

    2012-01-01

    AP Calculus AB & BC Crash Course - Gets You a Higher Advanced Placement Score in Less Time Crash Course is perfect for the time-crunched student, the last-minute studier, or anyone who wants a refresher on the subject. AP Calculus AB & BC Crash Course gives you: Targeted, Focused Review - Study Only What You Need to Know Crash Course is based on an in-depth analysis of the AP Calculus AB & BC course description outline and actual AP test questions. It covers only the information tested on the exams, so you can make the most of your valuable study time. Written by experienced math teachers, our

  17. IL-1beta-induced pro-apoptotic signalling is facilitated by NCAM/FGF receptor signalling and inhibited by the C3d ligand in the INS-1E rat beta cell line

    DEFF Research Database (Denmark)

    Petersen, L G; Størling, J; Heding, P

    2006-01-01

    AIMS/HYPOTHESIS: IL-1beta released from immune cells induces beta cell pro-apoptotic signalling via mitogen-activated protein kinases (MAPKs) and nuclear factor-kappaB (NF-kappaB). In neurons, the neural cell adhesion molecule (NCAM) signals to several elements involved in IL-1beta-induced pro-ap...

  18. Hadron star models. [neutron stars

    Science.gov (United States)

    Cohen, J. M.; Boerner, G.

    1974-01-01

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

  19. Glycopeptide profiling of beta-2-glycoprotein I by mass spectrometry reveals attenuated sialylation in patients with antiphospholipid syndrome

    DEFF Research Database (Denmark)

    Kondo, Akira; Miyamoto, Toshiaki; Yonekawa, Osamu;

    2009-01-01

    beta2-glycoprotein I (beta2GPI) is a five-domain protein associated with the antiphospholipid syndrome (APS), however, its normal biological function is yet to be defined. beta2GPI is N-glycosylated at several asparagine residues and the glycan moiety conjugated to residue 143 has been proposed...... and the pathology of antiphospholipid syndrome....

  20. Induction of anti-beta(2)-glycoprotein I autoantibodies in mice by protein H of Streptococcus pyogenes

    NARCIS (Netherlands)

    Van Os, G. M. A.; Meijers, J. C. M.; Agar, C.; Seron, M. V.; Marquart, J. A.; Akesson, P.; Urbanus, R. T.; Derksen, R. H. W. M.; Herwald, H.; Morgelin, M.; De Groot, P. G.

    2011-01-01

    Background: The antiphospholipid syndrome (APS) is characterized by the persistent presence of anti-beta 2-glycoprotein I (beta 2-GPI) autoantibodies. beta 2-GPI can exist in two conformations. In plasma it is a circular protein, whereas it adopts a fish-hook conformation after binding to phospholip

  1. Mode selection in pulsating stars

    CERN Document Server

    Smolec, R

    2013-01-01

    In this review we focus on non-linear phenomena in pulsating stars the mode selection and amplitude limitation. Of many linearly excited modes only a fraction is detected in pulsating stars. Which of them and why (the problem of mode selection) and to what amplitude (the problem of amplitude limitation) are intrinsically non-linear and still unsolved problems. Tools for studying these problems are briefly discussed and our understanding of mode selection and amplitude limitation in selected groups of self-excited pulsators is presented. Focus is put on classical pulsators (Cepheids and RR Lyrae stars) and main sequence variables (delta Scuti and beta Cephei stars). Directions of future studies are briefly discussed.

  2. On the nature of the {delta} Scuti star HD 115520

    Energy Technology Data Exchange (ETDEWEB)

    Pena, J H; Cervantes-Sodi, B; Cano, M; Sorcia, M A [Instituto de AstronomIa, Universidad Nacional Autonoma de Mexico, Mexico D.F., Apdo. Postal 70-264 (Mexico); Fox, L; Alvarez, M [Observatorio Astronomico Nacional, Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Ensenada B.C., Apdo. Postal 877 (Mexico); Pena, R [Facultad de Ciencias, Universidad Nacional Autonoma de Mexico, Mexico D.F. (Mexico); Munoz, G; Vargas, B [Escuela Superior de Ingenier Mecanica y Electrica, Instituto Politecnico Nacional, Av. IPN s/n, 07738 Mexico, D.F. (Mexico); Sareyan, J P [Observatoire de la Cote d' Azur (France)], E-mail: jhpena@astroscu.unam.mx

    2008-10-15

    Observing Delta Scuti stars is most important as their multi-frequency spectrum of radial pulsations provide strong constraints on the physics of the stars interior; so any new detection and observation of these stars is a valuable contribution to asteroseismology. While performing uvby-beta photoelectric photometry of some RR Lyrae stars acquired in 2005 at the Observatorio Astronomico Nacional, Mexico, we also observed several standard stars, HD115520 among them. After the reduction this star showed indications of variability. In view of this, a new observing run was carried out in 2006 during which we were able to demonstrate its variability and its nature as a Delta Scuti star. New observations in 2007 permitted us to determine its periodic content with more accuracy. This, along with the uvby-beta photoelectric photometry allowed us to deduce its physical characteristics and pulsational modes.

  3. Star Wreck

    OpenAIRE

    Kusenko, Alexander; Shaposhnikov, Mikhail E.; Tinyakov, P. G.; Tkachev, Igor I.

    1998-01-01

    Electroweak models with low-energy supersymmetry breaking predict the existence of stable non-topological solitons, Q-balls, that can be produced in the early universe. The relic Q-balls can accumulate inside a neutron star and gradually absorb the baryons into the scalar condensate. This causes a slow reduction in the mass of the star. When the mass reaches a critical value, the neutron star becomes unstable and explodes. The cataclysmic destruction of the distant neutron stars may be the or...

  4. Star polygons

    OpenAIRE

    Riosa, Blažka

    2014-01-01

    In mathematics we often encounter polygons, such us triangle, square, hexagon, etc., but we hardly encounter star polygons. Despite the fact that we do not meet them so often in mathematics, in nature they can be traced almost on every step. In this paper the emphasis is on the geometric meaning of regular star polygons. Star polygon is a generalization of the concept of regular polygons. In star polygons also non-adjacent sides intersect. Up to similarity they are determined by Schläfli symb...

  5. AP English language & composition crash course

    CERN Document Server

    Hogue, Dawn

    2012-01-01

    AP English Language & Composition Crash Course - Gets You a Higher Advanced Placement Score in Less Time Crash Course is perfect for the time-crunched student, the last-minute studier, or anyone who wants a refresher on the subject. AP English Language & Composition Crash Course gives you: Targeted, Focused Review - Study Only What You Need to Know Crash Course is based on an in-depth analysis of the AP English Language & Composition course description outline and actual Advanced Placement test questions. It covers only the information tested on the exam, so you can make the most of your valua

  6. Generic effluent monitoring system certification for AP-40 exhauster stack

    Energy Technology Data Exchange (ETDEWEB)

    Glissmeyer, J.A.; Davis, W.E.; Bussell, J.H.; Maughan, A.D.

    1997-09-01

    Tests were conducted to verify that the Generic Effluent Monitoring System (GEMS), as applied to the AP-40 exhauster stack, meets all applicable regulatory performance criteria for air sampling systems at nuclear facilities. These performance criteria address both the suitability of the air sampling probe location and the transport of the sample to the collection devices. The criteria covering air sampling probe location ensure that the contaminants in the stack are well mixed with the airflow at the probe location such that the extracted sample represents the whole. The sample transport criteria ensure that the sampled contaminants are quantitatively delivered to the collection device. The specific performance criteria are described in detail in the report. The tests demonstrated that the GEMS/AP-40 system meets all applicable performance criteria. The contaminant mixing tests were conducted by Pacific Northwest National Laboratory (PNNL) at the wind tunnel facility, 331-H Building, using a mockup of the actual stack. The particle sample transport tests were conducted by PNNL at the Numatec Hanford Company`s 305 Building. The AP-40 stack is typical of several 10-in. diameter stacks that discharge the filtered ventilation air from tank farms at the U.S. Department of Energy`s Hanford Site in Richland, Washington. The GEMS design features a probe with a single shrouded sampling nozzle, a sample delivery line, and sample collection system. The collection system includes a filter holder to collect the sample of record and an in-line detector head and filter for monitoring beta radiation-emitting particles. Unrelated to the performance criteria, it was found that the record sample filter holder exhibited symptoms of sample bypass around the particle collection filter. This filter holder should either be modified or replaced with a different type. 10 refs., 8 figs., 6 tabs.

  7. Chromospheric changes in K stars with activity

    CERN Document Server

    Vieytes, Mariela; Diaz, Rodrigo

    2009-01-01

    We study the differences in chromospheric structure induced in K stars by stellar activity, to expand our previous work for G stars, including the Sun as a star. We selected six stars of spectral type K with 0.82$stars in the sample, in most cases in two different moments of activity. The models were constructed to obtain the best possible match with the Ca II K and the H$\\beta$ observed profiles. We also computed in detail the net radiative losses for each model to constrain the heating mechanism that can maintain the structure in the atmosphere. We find a strong correlation between these losses and \\Sc, the index generally used as a proxy for activity, as we found for G stars.

  8. A Novel Dimeric Inhibitor Targeting Beta2GPI in Beta2GPI/Antibody Complexes Implicated in Antiphospholipid Syndrome

    Energy Technology Data Exchange (ETDEWEB)

    A Kolyada; C Lee; A De Biasio; N Beglova

    2011-12-31

    {beta}2GPI is a major antigen for autoantibodies associated with antiphospholipid syndrome (APS), an autoimmune disease characterized by thrombosis and recurrent pregnancy loss. Only the dimeric form of {beta}2GPI generated by anti-{beta}2GPI antibodies is pathologically important, in contrast to monomeric {beta}2GPI which is abundant in plasma. We created a dimeric inhibitor, A1-A1, to selectively target {beta}2GPI in {beta}2GPI/antibody complexes. To make this inhibitor, we isolated the first ligand-binding module from ApoER2 (A1) and connected two A1 modules with a flexible linker. A1-A1 interferes with two pathologically important interactions in APS, the binding of {beta}2GPI/antibody complexes with anionic phospholipids and ApoER2. We compared the efficiency of A1-A1 to monomeric A1 for inhibition of the binding of {beta}2GPI/antibody complexes to anionic phospholipids. We tested the inhibition of {beta}2GPI present in human serum, {beta}2GPI purified from human plasma and the individual domain V of {beta}2GPI. We demonstrated that when {beta}2GPI/antibody complexes are formed, A1-A1 is much more effective than A1 in inhibition of the binding of {beta}2GPI to cardiolipin, regardless of the source of {beta}2GPI. Similarly, A1-A1 strongly inhibits the binding of dimerized domain V of {beta}2GPI to cardiolipin compared to the monomeric A1 inhibitor. In the absence of anti-{beta}2GPI antibodies, both A1-A1 and A1 only weakly inhibit the binding of pathologically inactive monomeric {beta}2GPI to cardiolipin. Our results suggest that the approach of using a dimeric inhibitor to block {beta}2GPI in the pathological multivalent {beta}2GPI/antibody complexes holds significant promise. The novel inhibitor A1-A1 may be a starting point in the development of an effective therapeutic for antiphospholipid syndrome.

  9. STAR Calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, W W, E-mail: jacobsw@indiana.ed [Indiana University Cyclotron Facility and Department of Physics, 2401 Milo B. Sampson Lane, Bloomington IN 47408 (United States)

    2009-04-01

    The main STAR calorimeters comprise a full Barrel EMC and single Endcap EMC plus a Forward Meson Spectrometer. Together they give a nearly complete coverage over the range -1 < pseudorapidity < 4 and provide EM readout and triggering that help drive STAR physics capabilities. Their description, status, performance and operations (and a few physics anecdotes) are briefly presented and discussed.

  10. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Brorsen, Michael; Frigaard, Peter

    Nærværende rapport beskriver numeriske beregninger af den hydrodynamiske interaktion mellem 5 flydere i bølgeenergianlægget Wave Star.......Nærværende rapport beskriver numeriske beregninger af den hydrodynamiske interaktion mellem 5 flydere i bølgeenergianlægget Wave Star....

  11. Star Imager

    DEFF Research Database (Denmark)

    Madsen, Peter Buch; Jørgensen, John Leif; Thuesen, Gøsta;

    1997-01-01

    The version of the star imager developed for Astrid II is described. All functions and features are described as well as the operations and the software protocol.......The version of the star imager developed for Astrid II is described. All functions and features are described as well as the operations and the software protocol....

  12. No detection of large-scale magnetic fields at the surfaces of Am and HgMn stars

    CERN Document Server

    Auriere, M; Lignieres, F; Hui-Bon-Hoa, A; Landstreet, J D; Iliev, I; Donati, J -F; Petit, P; Roudier, T; Theado, S

    2010-01-01

    We investigate the magnetic dichotomy between Ap/Bp and other A-type stars by carrying out a deep spectropolarimetric study of Am and HgMn stars. Using the NARVAL spectropolarimeter at the Telescope Bernard Lyot (Observatoire du Pic du Midi, France), we obtained high-resolution circular polarisation spectroscopy of 12 Am stars and 3 HgMn stars. Using Least Squares Deconvolution (LSD), no magnetic field is detected in any of the 15 observed stars. Uncertaintiies as low as 0.3 G (respectively 1 G) have been reached for surface-averaged longitudinal magnetic field measurements for Am (respectively HgMn) stars. Associated with the results obtained previously for Ap/Bp stars, our study confirms the existence of a magnetic dichotomy among A-type stars. Our data demonstrate that there is at least one order of magnitude difference in field strength between Zeeman detected stars (Ap/Bp stars) and non Zeeman detected stars (Am and HgMn stars). This result confirms that the spectroscopically-defined Ap/Bp stars are the ...

  13. Pentoxifylline Treatment in Acute Pancreatitis (AP)

    Science.gov (United States)

    2016-09-14

    Acute Pancreatitis (AP); Gallstone Pancreatitis; Alcoholic Pancreatitis; Post-ERCP/Post-procedural Pancreatitis; Trauma Acute Pancreatitis; Hypertriglyceridemia Acute Pancreatitis; Idiopathic (Unknown) Acute Pancreatitis; Medication Induced Acute Pancreatitis; Cancer Acute Pancreatitis; Miscellaneous (i.e. Acute on Chronic Pancreatitis)

  14. Peculiar Traits of Coarse AP (Briefing Charts)

    Science.gov (United States)

    2014-12-01

    Self Combustion 3 Thom L. Boggs Parallel ridges and valley surfaces seen at 1000 to 1500 psi Isolated AP vertical needle pockets at 1500 and 1800 psi...Negative exponents, bouncing flamlets between 2000 to 4000 psi Extremely irregular AP surface regression Hightower and Price 16 Air Force Research...supported by vertical gas jetlets from active centers? Did Boggs burn a few samples at 1000 to 2000 psi with orthorhombic main axis normal to

  15. Tank 241-AP-106, Grab samples, 6AP-98-1, 6AP-98-2 and 6AP-98-3 Analytical results for the final report

    Energy Technology Data Exchange (ETDEWEB)

    FULLER, R.K.

    1999-02-23

    This document is the final report for tank 241-AP-106 grab samples. Three grab samples 6AP-98-1, 6AP-98-2 and 6AP-98-3 were taken from riser 1 of tank 241-AP-106 on May 28, 1998 and received by the 222-S Laboratory on May 28, 1998. Analyses were performed in accordance with the ''Compatability Grab Sampling and Analysis Plan'' (TSAP) (Sasaki, 1998) and the ''Data Quality Objectives for Tank Farms Waste Compatability Program (DQO). The analytical results are presented in the data summary report. No notification limits were exceeded. The request for sample analysis received for AP-106 indicated that the samples were polychlorinated biphenyl (PCB) suspects. The results of this analysis indicated that no PCBs were present at the Toxic Substance Control Act (TSCA) regulated limit of 50 ppm. The results and raw data for the PCB analysis are included in this document.

  16. Planetary companions in K giants beta Cancri, mu Leonis, and beta Ursae Minoris

    CERN Document Server

    Lee, B -C; Park, M -G; Mkrtichian, D E; Hatzes, A P; Kim, K -M

    2014-01-01

    Auns. The aim of our paper is to investigate the low-amplitude and long-period variations in evolved stars with a precise radial velocity (RV) survey. Methods. The high-resolution, the fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) was used from 2003 to 2013 for a radial velocity survey of giant stars as part of the exoplanet search program at Bohyunsan Optical Astronomy Observatory (BOAO). Results. We report the detection of three new planetary companions orbiting the K giants beta Cnc, mu Leo, and beta UMi. The planetary nature of the radial velocity variations is supported by analyzes of ancillary data. The HIPPARCOS photometry shows no variations with periods close to those in RV variations and there is no strong correlation between the bisector velocity span (BVS) and the radial velocities for each star. Furthermore, the stars show weak or no core reversal in Ca II H lines indicating that they are inactive stars. The companion to beta Cnc has a minimum mass of 7.8 M_Jup in a 605-day orbit wi...

  17. 51 Eri and GJ 3305: A 10-15 Myr old binary star system at 30 parsecs

    CERN Document Server

    Feigelson, E D; Stark, M; Townsley, L; Garmire, G P; State, P; State, Penn

    2005-01-01

    Following the suggestion of Zuckerman et al. (2001, ApJ, 562, L87), we consider the evidence that 51 Eri (spectral type F0) and GJ 3305 (M0), historically classified as unrelated main sequence stars in the solar neighborhood, are instead a wide physical binary system and members of the young beta Pic moving group (BPMG). The BPMG is the nearest (d < 50 pc) of several groups of young stars with ages around 10 Myr that are kinematically convergent with the Oph-Sco-Cen Association (OSCA), the nearest OB star association. Combining SAAO optical photometry, Hobby-Eberly Telescope high-resolution spectroscopy, Chandra X-ray data, and UCAC2 catalog kinematics, we confirm with high confidence that the system is indeed extremely young. GJ 3305 itself exhibits very strong magnetic activity but has rapidly depleted most of its lithium. The 51 Eri/GJ 3305 system is the westernmost known member of the OSCA, lying 110 pc from the main subgroups. The system is similar to the BPMG wide binary HD 172555/CD -64d1208 and the...

  18. Magnetic fields of neutron stars

    CERN Document Server

    Reisenegger, Andreas

    2013-01-01

    Neutron stars contain the strongest magnetic fields known in the Universe. In this paper, I discuss briefly how these magnetic fields are inferred from observations, as well as the evidence for their time-evolution. I show how these extremely strong fields are actually weak in terms of their effects on the stellar structure, as is also the case for magnetic stars on the upper main sequence and magnetic white dwarfs, which have similar total magnetic fluxes. I propose a scenario in which a stable hydromagnetic equilibrium (containing a poloidal and a toroidal field component) is established soon after the birth of the neutron star, aided by the strong compositional stratification of neutron star matter, and this state is slowly eroded by non-ideal magnetohydrodynamic processes such as beta decays and ambipolar diffusion in the core of the star and Hall drift and breaking of the solid in its crust. Over sufficiently long time scales, the fluid in the neutron star core will behave as if it were barotropic, becau...

  19. Rising Star

    OpenAIRE

    Worley, Christiana

    2012-01-01

    Rising Star is a novel about appearances. Thailand Allen is a girl who thinks she understands what she sees. But when what she sees are cracks in her perfect world, maturation and new sight are not far off. Before growth can occur, Thailand must undergo a painful process of learning that carries with it embarrassment, sorrow, anger and confusion. Thailand lives with her mother in a small Texas town called Rising Star. Rising Star is like every other small town with its community gather...

  20. Lactogenic differentiation of HC11 cells is not accompanied by downregulation of AP-2 transcription factor genes

    Directory of Open Access Journals (Sweden)

    Schorle Hubert

    2008-06-01

    Full Text Available Abstract Background During pregnancy the mammary epithelium undergoes a complex developmental process which culminates in the generation of the milk-secreting epithelium. Secretory epithelial cells display lactogenic differentiation which is characterized by the expression of milk protein genes, such as beta-casein or whey acidic protein (WAP. Transcription factors AP-2alpha and AP-2gamma are downregulated during lactation, and their overexpression in transgenic mice impaired the secretory differentiation of the mammary epithelium, resulting in lactation failure. To explore whether the downregulation of AP-2alpha and AP-2gamma is of functional significance for lactogenic differentiation, we analyzed the expression of the AP-2 family members during the lactogenic differentiation of HC11 mammary epithelial cells in vitro. Differentiation of HC11 cells was induced following established protocols by applying the lactogenic hormones prolactin, dexamethasone and insulin. Findings HC11 cells express all AP-2 family members except AP-2delta. Using RT-PCR we could not detect a downregulation of any of these genes during the lactogenic differentiation of HC11 cells in vitro. This finding was confirmed for AP-2alpha and AP-2gamma using Northern analysis. Differentiating HC11 cells displayed lower expression levels of milk protein genes than mammary glands of mid-pregnant or lactating mice. Conclusion The extent of lactogenic differentiation of HC11 cells in vitro is limited compared to mammary epithelium undergoing secretory differentiation in vivo. Downregulation of AP-2 transcription factor genes is not required for lactogenic differentiation of HC11 cells but may functionally be involved in aspects of lactogenic differentiation in vivo that are not reflected by the HC11 system.

  1. Antibodies to endothelial cells and to beta 2-glycoprotein I in the antiphospholipid syndrome: prevalence and isotype distribution.

    Science.gov (United States)

    Navarro, M; Cervera, R; Teixidó, M; Reverter, J C; Font, J; López-Soto, A; Monteagudo, J; Escolar, G; Ingelmo, M

    1996-06-01

    The aim of this study was to analyse the prevalence and isotype distribution of antibodies to endothelial cells (aEC) and to beta 2-glycoprotein I (a beta 2GPI) in the antiphospholipid syndrome (APS). Fifteen patients with an APS [nine associated with systemic lupus erythematosus (SLE) and six "primary'] and 15 with SLE without an APS were prospectively studied. The aEC were determined by an enzyme-linked immunosorbent assay (ELISA) using endothelial cells derived from human umbilical vein and the a beta 2GPI by ELISA using highly purified beta 2GPI. A positive titre of aEC was detected in 20 out of 30 patients (67%), but in none of the control group. Ten patients had both IgG and IgM isotypes, five had IgG only and five had only IgM. Thirteen patients with the APS (87%) were found to have a positive titre of aEC, while only seven with SLE but without a history of APS (47%) had aEC (P < 0.05). Nine patients with the APS (60%) had a positive titre of a beta 2GPI (four had both IgG and IgM isotypes, one had IgG only and four had only IgM), while none of the patients without an APS (0%) had these antibodies (P < 0.001). A significant association was also found between the presence of aPL and aEC (P < 0.05), as well as between aPL and a beta 2GPI (P < 0.001). Both aEC and a beta 2GPI can be found in the APS. This reinforces the theory that APS represents a complex autoimmune disorder in which several autoantibodies co-exist with aPL.

  2. Magnetic fields in non-convective regions of stars

    CERN Document Server

    Braithwaite, J

    2015-01-01

    We review the current state of knowledge of magnetic fields inside stars, concentrating on recent developments concerning magnetic fields in stably stratified (zones of) stars, leaving out convective dynamo theories and observations of convective envelopes. We include the observational properties of A, B and O-type main-sequence stars, which have radiative envelopes, and the fossil field model which is normally invoked to explain the strong fields sometimes seen in these stars. Observations seem to show that Ap-type stable fields are excluded in stars with convective envelopes. Most stars contain both radiative and convective zones, and there are potentially important effects arising from the interaction of magnetic fields at the boundaries between them, the solar cycle being one of the better known examples. Related to this, we discuss whether the Sun could harbour a magnetic field in its core. Recent developments regarding the various convective and radiative layers near the surfaces of early-type stars and...

  3. Carbon Stars

    Indian Academy of Sciences (India)

    T. Lloyd Evans

    2010-12-01

    In this paper, the present state of knowledge of the carbon stars is discussed. Particular attention is given to issues of classification, evolution, variability, populations in our own and other galaxies, and circumstellar material.

  4. Rock Stars

    Institute of Scientific and Technical Information of China (English)

    张国平

    2000-01-01

    Around the world young people are spending unbelievable sums of money to listen to rock music. Forbes Magazine reports that at least fifty rock stars have incomes between two million and six million dollars per year.

  5. Instability strips of main sequence B stars: a parametric study of iron enhancement

    CERN Document Server

    Miglio, A; Montalban, J; Dupret, M A

    2006-01-01

    The discovery of beta Cephei stars in low metallicity environments, as well as the difficulty to theoretically explain the excitation of the pulsation modes observed in some beta Cephei and SPB stars, suggest that the iron opacity ``bump'' provided by standard models could be underestimated. We investigate, by means of a parametric study, the effect of a local iron enhancement on the location of the beta Cephei and SPB instability strips.

  6. Orbital parameters, chemical composition, and magnetic field of the Ap binary HD 98088

    CERN Document Server

    Folsom, C P; Wade, G A; Kochukhov, O; Alecian, E; Shulyak, D

    2013-01-01

    HD 98088 is a synchronised, double-lined spectroscopic binary system with a magnetic Ap primary component and an Am secondary component. We study this rare system using high-resolution MuSiCoS spectropolarimetric data, to gain insight into the effect of binarity on the origin of stellar magnetism and the formation of chemical peculiarities in A-type stars. Using a new collection of 29 high-resolution Stokes VQU spectra we re-derive the orbital and stellar physical parameters and conduct the first disentangling of spectroscopic observations of the system to conduct spectral analysis of the individual stellar components. From this analysis we determine the projected rotational velocities of the stars and conduct a detailed chemical abundance analysis of each component using both the SYNTH3 and ZEEMAN spectrum synthesis codes. The surface abundances of the primary component are typical of a cool Ap star, while those of the secondary component are typical of an Am star. We present the first magnetic analysis of b...

  7. Hyperon Stars in Strong Magnetic Fields

    CERN Document Server

    Gomes, R O; Vasconcellos, C A Z

    2013-01-01

    We investigate the effects of strong magnetic fields on the properties of hyperon stars. The matter is described by a hadronic model with parametric coupling. The matter is considered to be at zero temperature, charge neutral, beta-equilibrated, containing the baryonic octet, electrons and muons. The charged particles have their orbital motions Landau-quantized in the presence of strong magnetic fields (SMF). Two parametrisations of a chemical potential dependent static magnetic field are considered, reaching $1-2 \\times 10^{18}\\,G$ in the center of the star. Finally, the Tolman-Oppenheimer-Volkov (TOV) equations are solved to obtain the mass-radius relation and population of the stars.

  8. Precision age indicators that exploit chemically peculiar stars

    CERN Document Server

    Worthey, Guy

    2015-01-01

    We would like to find a way to improve the determination of galaxy star formation history from integrated light spectroscopy. To this end, several classes of chemically peculiar (CP) stars arise during the course of normal evolution in single stars and noninteracting binary stars. An aging stellar population has periods of time in which CP stars contribute to the integrated light, and others in which the contributions fade. The HgMn stars, for example, occupy a narrow temperature range of 10500 to 16000 K, which maps to a narrow range of ages. Wolf-Rayet stars, He-poor stars, Bp-Ap stars, Am-Fm stars, and C stars all become very common in a normal stellar population at various ages between zero and several Gyr, fading in and out in a way that is analogous to features used in stellar spectral classification. We examine population fractions and light fractions in order to assess the feasibility of using CP stars as age tracers. We find that, even though CP stars do not usually dominate in number, there are enou...

  9. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Frigaard, Peter

    Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Byggeri og Anlæg med bølgeenergianlæget Wave Star.......Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Byggeri og Anlæg med bølgeenergianlæget Wave Star....

  10. STAR POLYMERS

    OpenAIRE

    Ch. von Ferber; Yu.Holovatch

    2002-01-01

    It is our great pleasure to present a collection of papers devoted to theoretical, numerical, and experimental studies in the field of star polymers. Since its introduction in the early 80-ies, this field has attracted increasing interest and has become an important part of contemporary polymer physics. While research papers in this field appear regularly in different physical and chemical journals, the present collection is an attempt to join together the studies of star polymers showing the...

  11. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Andersen, Thomas Lykke

    Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star.......Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star....

  12. Center for Geometrisk Metrologi CGM ApS, Årsberetning 2001 til DANAK

    DEFF Research Database (Denmark)

    De Chiffre, Leonardo

    Denne årsberetning omfatter CGM ApS' akkrediterede virksomhed i kalenderåret 2001. Årsberetningen er udarbejdet til DANAK (Dansk Akkreditering, Erhvervsfremme Styrelsen), som led i opfyldelsen af laboratoriets informationspligt i henhold til gældende regler (Teknisk Forskrift Nr. TF4 af 2000...

  13. New results of the spectral observations of CP stars

    Science.gov (United States)

    Polosukhina, N. S.; Shavrina, A. V.; Drake, N. A.; Kudryavtsev, D. O.; Smirnova, M. A.

    2010-04-01

    The lithium problem in Ap-CP stars has been, for a long time, a subject of debate. Individual characteristics of CP stars, such as high abundance of the rare-earth elements presence of magnetic fields, complicate structure of the surface distribution of chemical elements, rapid oscillations of some CP-stars, make the detection of the lithium lines and the determination of the lithium abundance, a difficult task. During the International Meeting in Slovakia in 1996, the lithium problem in Ap-CP stars was discussed. The results of the Li study carried out in CrAO Polosukhina (1973-1976), the works of Hack & Faraggiana (1963), Wallerstein & Hack (1964), Faraggiana et al. (1992-1996) formed the basis of the International project ‘Lithium in the cool CP-stars with magnetic fields’. The main goal of the project was, using systematical observations of Ap-CP stars with phase rotation in the spectral regions of the resonance doublet Li I 6708 Å and subordinate 6104 Å lithium lines with different telescopes, to create a database, which will permit to explain the physical origin of anomalous Li abundance in the atmospheres of these stars.

  14. AP1000, a nuclear central of advanced design; AP1000, una central nuclear de diseno avanzado

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez M, N.; Viais J, J. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)]. e-mail: nhm@nuclear.inin.mx

    2005-07-01

    The AP1000 is a design of a nuclear reactor of pressurized water (PWR) of 1000 M We with characteristic of safety in a passive way; besides presenting simplifications in the systems of the plant, the construction, the maintenance and the safety, the AP1000 is a design that uses technology endorsed by those but of 30 years of operational experience of the PWR reactors. The program AP1000 of Westinghouse is focused to the implementation of the plant to provide improvements in the economy of the same one and it is a design that is derived directly of the AP600 designs. On September 13, 2004 the US-NRC (for their initials in United States- Nuclear Regulatory Commission) approved the final design of the AP1000, now Westinghouse and the US-NRC are working on the whole in a complete program for the certification. (Author)

  15. Formalistic approaches to A&P

    Institute of Scientific and Technical Information of China (English)

    赵倩

    2014-01-01

    A&P is a famous short story. Its simple words, the unique point of view and skillful writing technique are expressed successfully. Besides, the first-person narrator is also a good point. From Sammy’s eyes, readers can learn the character’s characteristics. Another point is the usage of symbol, the name of the store, A&P, it shows that people’s life is rich, but their spirit is barren. This article tries to analyze it by formalistic approaches.

  16. An analysis of AP600 design features

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jong Kyoon; Jang, Moon Heui; Hwang, Yung Dong [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)] [and others

    1994-01-01

    In the aspect of engineering, passive safety system concept has improved the safety degree of nuclear power plant. Therefore, the objective of this study is to check on the possibility of the capacity upgrade of nuclear power plant in the case of adopting the passive safety system concept of AP 600. The characteristics of AP 600 are the advanced functions in ECCS, heat removal of containment building and residual heat removal under the passive safety system concept. The result of this study will become the basic data of capacity upgrade of nuclear power plant and will be widely used in second year project. (Author).

  17. 2000 Johnston Site 3A-P

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Underwater Site 3A-P was established at Johnston Atoll by Dr. James Maragos, U.S. Fish & Wildlife Service, on July 3, 2000. With a start point (meter 0) at...

  18. 2000 Johnston Site 1A-P

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Underwater Site 1A-P was established at Johnston Atoll by Dr. James Maragos, U.S. Fish & Wildlife Service, on June 29, 2000. With a start point (meter 0) at...

  19. 2000 Johnston Site 2A-P

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Underwater Site 2A-P was established at Johnston Atoll by Dr. James Maragos, U.S. Fish & Wildlife Service, on June 30, 2000. With a start point (meter 0) at...

  20. 2006 Johnston Site 1A-P

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Underwater Site 1A-P was established at Johnston Atoll by Dr. James Maragos, U.S. Fish & Wildlife Service, on June 29, 2000. With a start point (meter 0) at...

  1. Structuring the AP Art History Course

    Science.gov (United States)

    Herscher, Walter R.

    2013-01-01

    While AP (Advanced Placement) Art History may be taught within the art department in many schools, social studies teachers are equally capable of teaching the course well. They have the historical background to discuss the reasons for changes in art styles. A teacher's preparation is similar to teaching a course stressing political history,…

  2. Barron's AP English literature and composition

    CERN Document Server

    Ehrenhaft EdD, George

    2016-01-01

    Includes five full-length practice AP exams with all questions answered and explained. Also features additional reviews on poetry, fiction, and drama, definitions of 175 literary and rhetorical terms, and more. Can be purchased alone or with an optional CD-ROM with two additional practice tests.

  3. Two Successful Approaches to Teaching AP Government

    Science.gov (United States)

    Ladd, Brian; Stepp, Heidi

    2013-01-01

    Amador Valley High School, in Pleasanton, California, uses two unique approaches to teaching Advanced Placement Government and Politics. AP Government consists of six units: Constitutional Underpinnings; Political Behavior and Political Beliefs; Mass Media, Interest Groups, and Political Parties; Institutions of Government; Civil Liberties and…

  4. Morning Star

    OpenAIRE

    Harris, Mark

    2010-01-01

    Morning Star comprises a group of paintings and drawings whose imagery derives from photographs of 1960s American hippie communes. The paintings are made using oil paint on linen. Their dimensions vary between 180 x 120, and 228 x 217 centimetres. The drawings are in pencil on watercolour paper and are all 56 x 76 centimetres. The work has been exhibited in conventional form, hanging on gallery walls. For Morning Star I made pencil drawings and oil paintings derived from images in Dick Fa...

  5. Beta-carotene

    Science.gov (United States)

    ... patches on the tongue and mouth called oral leukoplakia. Taking beta-carotene by mouth for up to 12 months seems to decrease symptoms of oral leukoplakia. Osteoarthritis. Beta-carotene taken by mouth may prevent ...

  6. Stars Underground

    CERN Multimedia

    Jean Leyder

    1996-01-01

    An imaginary voyage in time where we were witness of the birth of the universe itself, the time of the Big-Bang 15 billion years ago. Particules from the very first moments of time : protons, neutrons and electrons, and also much more energetic one. These particules are preparing to interact collider and generating others which will be the birth to the stars ........

  7. Pulsating stars

    CERN Document Server

    Catelan, M?rcio

    2014-01-01

    The most recent and comprehensive book on pulsating stars which ties the observations to our present understanding of stellar pulsation and evolution theory.  Written by experienced researchers and authors in the field, this book includes the latest observational results and is valuable reading for astronomers, graduate students, nuclear physicists and high energy physicists.

  8. STAR Highlights

    OpenAIRE

    Masui, Hiroshi; collaboration, for the STAR

    2011-01-01

    We report selected results from STAR collaboration at RHIC, focusing on jet-hadron and jet-like correlations, quarkonium suppression and collectivity, di-electron spectrum in both p+p and Au+Au, and higher moments of net-protons as well as azimuthal anisotropy from RHIC Beam Energy Scan program.

  9. Expression of a novel beta adaptin subunit mRNA splice variant in human testes

    Institute of Scientific and Technical Information of China (English)

    Xin-Dong Zhang; Lan-Lan Yin; Ying Zheng; Li Lu; Zuo-Min Zhou; Jia-Hao Sha

    2005-01-01

    Aim: To identify a novel isoform of adaptin 2 beta subunit (named Ap2β-NY) and to investigate its relationship with testicular development and spermatogenesis. Methods: Using a human testis cDNA microarray, a clone (Ap2β-NY),which was strongly expressed in adult testes but weakly expressed in embryo testes, was sequenced and analyzed.Using polymerase chain reaction (PCR), the tissue distribution and expression time pattern of Ap2β-NY were determined.Results: Ap2β-NY was identified and has been deposited in the GenBank (AY341427). The expression level of Ap2β-NY in the adult testis was about 3-fold higher than that in the embryo testis. PCR analysis using multi-tissue cDNA indicated that Ap2β-NY was highly expressed in the testis, spleen, thymus, prostate, ovary, blood leukocyte and brain, but not in the heart, placenta, lung, liver, skeletal muscle, kidney and pancreas. In addition, Ap2β-NY was variably expressed in the testes of patients with spermatogenesis-disturbance and spermatogenesis-arrest but not expressed in those of Sertoli-cell-only syndrome, which implied that, in the testis, Ap2β-NY was restrictively expressed in germ cells. Conclusion: Ap2β-NY is an isoform of Ap2β and may be involved in regulating the process of spermatogenesis and testis development.

  10. AE8/AP8 Implementations in AE9/AP9, IRBEM, and SPENVIS

    Science.gov (United States)

    2014-02-18

    period applies to orbit generation only; AE8/AP8 utilizes geomagnetic field models from other epochs as specified in the table below.) SHIELDOSE2 model...Cain, J. C., S. J. Hendricks, R. A. Langel, and W. V. Hudson (1967), A proposed model for the international geomagnetic reference field, 1965, J...trapped particle fluxes with the NASA models AP-8 and AE-8, Radiat. Meas., 26, pp. 947-952. International Association of Geomagnetism and Aeronomy

  11. Period Changes and Evolution in Pulsating Variable Stars

    Science.gov (United States)

    Neilson, H. R.; Percy, J. R.; Smith, H. A.

    2016-12-01

    We review ways in which observations of the changing periods of pulsating variable stars can be used to detect and directly measure their evolution. We briefly describe the two main techniques of analysis-(O-C) analysis and wavelet analysis - and results for pulsating variable star types which are reasonably periodic: type I and II Cepheids, RR Lyrae stars, beta Cephei stars, and Mira stars. We comment briefly on delta Scuti stars and pulsating white dwarfs. For some of these variable star types, observations agree approximately with the predictions of evolutionary models, but there still exist significant areas of disagreement that challenge future models of stellar evolution. There may be a need, for instance, to include processes such as rotation, mass loss, and magnetic fields. There may also be non-evolutionary processes which are contributing to the period changes.

  12. Period Changes and Evolution in Pulsating Variable Stars

    CERN Document Server

    Neilson, Hilding R; Smith, Horace A

    2016-01-01

    We review ways in which observations of the changing periods of pulsating variable stars can be used to detect and directly measure their evolution. We briefly describe the two main techniques of analysis -- (O-C) analysis and wavelet analysis -- and results for pulsating variable star types which are reasonably periodic: type I and II Cepheids, RR Lyrae stars, beta Cephei stars, and Mira stars. We comment briefly on delta Scuti stars and pulsating white dwarfs. For some of these variable star types, observations agree approximately with the predictions of evolutionary models, but there still exist significant areas of disagreement that challenge future models of stellar evolution. There may be a need, for instance, to include processes such as rotation, mass loss, and magnetic fields. There may also be non-evolutionary processes which are contributing to the period changes.

  13. Comparative analysis between radiographic views for knee osteoarthrosis (bipedal AP versus monopedal AP

    Directory of Open Access Journals (Sweden)

    Rodrigo Pires e Albuquerque

    2013-08-01

    Full Text Available OBJECTIVE: A comparative analysis by applying the criteria of the original classification Ahlbäck in the anteroposterior (AP bipedal knee in extension and anteroposterior (AP monopodal knee in symptomatic knee arthrosis. With this analysis we intend to observe the agreement, any advantage or difference between the incidence and degree of joint involvement between the orthopedic surgeons and radiologists with the referring physician. METHODS: From January 2012 to March 2012, was a prospective study of 60 symptomatic arthrosis knees (60 patients, clinically selected group of outpatient knee and radiographic proposals submitted to the search. Of the 60 patients, 39 were female and 21 male, mean age 64 years (ranging from 50 to 84 years. Of the 60 knees studied, 37 corresponded to the right side and 23 on the left side. Statistical analysis was performed by Kappa statistics, which evaluates the interobserver agreement for qualitative data. RESULTS: According to the scale of Ahlbäck, there was a significant agreement (p < 0.0001 intra-observer in the classification of knee osteoarthritis among the five evaluators. There was a significant agreement (p < 0.0001 with inter-observer referring physician in the incidence of AP monopodal and AP bipedal for the four raters. CONCLUSION: The study found no difference between the incidence in the AP monopodal versus AP bipedal in osteoarthritis of the knee.

  14. Final report for tank 241-AP-108, grab samples 8AP-96-1, 8AP-96-2 and 8AP-96-FB

    Energy Technology Data Exchange (ETDEWEB)

    Esch, R.A.

    1996-04-19

    This document is the final report deliverable for the tank 241-AP-108 grab samples. The samples were subsampled and analyzed in accordance with the TSAP. Included in this report are the results for the Waste Compatibility analyses, with the exception of DSC and thermogravimetric analysis (TGA) results which were presented in the 45 Day report (Part 2 of this document). The raw data for all analyses, with the exception of DSC and TGA, are also included in this report.

  15. An Updated AP2 Beamline TURTLE Model

    Energy Technology Data Exchange (ETDEWEB)

    Gormley, M.; O' Day, S.

    1991-08-23

    This note describes a TURTLE model of the AP2 beamline. This model was created by D. Johnson and improved by J. Hangst. The authors of this note have made additional improvements which reflect recent element and magnet setting changes. The magnet characteristics measurements and survey data compiled to update the model will be presented. A printout of the actual TURTLE deck may be found in appendix A.

  16. Using DCAT-AP for research data

    OpenAIRE

    PEREGO ANDREA; FRIIS-CHRISTENSEN Anders; VACCARI LORENZINO; TSINARAKI CHRYSI

    2016-01-01

    This paper outlines a set cross-domain requirements for the documentation of scientific data, identified during the development of the corporate data catalogue of the European Commission's Joint Research Centre (JRC). In particular, we illustrate how we have extended the DCAT application profile for European data portals (DCAT-AP) to accomodate requirements for scientific datasets, and we discuss a number of issues still to be addressed.

  17. Cultural Diversity in AP Art History

    Science.gov (United States)

    Bolte, Frances R.

    2006-01-01

    Teaching AP Art History is like running on a treadmill that is moving faster than a teacher can run. Many teachers are out of breath before the end of the term and wonder how in the world they can cover every chapter. Because time is short and art from pre-history through to the present, including the non-European traditions, must be covered, this…

  18. Forward-Looking Betas

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Jacobs, Kris; Vainberg, Gregory

    Few issues are more important for finance practice than the computation of market betas. Existing approaches compute market betas using historical data. While these approaches differ in terms of statistical sophistication and the modeling of the time-variation in the betas, they are all backward......-looking. This paper introduces a radically different approach to estimating market betas. Using the tools in Bakshi and Madan (2000) and Bakshi, Kapadia and Madan (2003) we employ the information embedded in the prices of individual stock options and index options to compute our forward-looking market beta...

  19. Task Force on Catastrophic Antiphospholipid Syndrome (APS) and Non-criteria APS Manifestations (II): thrombocytopenia and skin manifestations.

    Science.gov (United States)

    Cervera, R; Tektonidou, M G; Espinosa, G; Cabral, A R; González, E B; Erkan, D; Vadya, S; Adrogué, H E; Solomon, M; Zandman-Goddard, G; Shoenfeld, Y

    2011-02-01

    The objectives of the 'Task Force on Catastrophic Antiphospholipid Syndrome (APS) and Non-criteria APS Manifestations' were to assess the clinical utility of the international consensus statement on classification criteria and treatment guidelines for the catastrophic APS, to identify and grade the studies that analyze the relationship between the antiphospholipid antibodies and the non-criteria APS manifestations, and to present the current evidence regarding the accuracy of these non-criteria APS manifestations for the detection of patients with APS. This article summarizes the studies analyzed on thrombocytopenia and skin manifestations, and presents the recommendations elaborated by the Task Force after this analysis.

  20. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Frigaard, Peter; Brorsen, Michael

    Nærværende rapport beskriver foreløbige hovedkonklusioner på modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star i perioden 13/9 2004 til 12/11 2004.......Nærværende rapport beskriver foreløbige hovedkonklusioner på modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star i perioden 13/9 2004 til 12/11 2004....

  1. AIRE variations in Addison's disease and autoimmune polyendocrine syndromes (APS)

    DEFF Research Database (Denmark)

    Bøe Wolff, A S; Oftedal, B; Johansson, S

    2008-01-01

    Autoimmune Addison's disease (AAD) is often associated with other components in autoimmune polyendocrine syndromes (APS). Whereas APS I is caused by mutations in the AIRE gene, the susceptibility genes for AAD and APS II are unclear. In the present study, we investigated whether polymorphisms...... or copy number variations in the AIRE gene were associated with AAD and APS II. First, nine SNPs in the AIRE gene were analyzed in 311 patients with AAD and APS II and 521 healthy controls, identifying no associated risk. Second, in a subgroup of 25 of these patients, AIRE sequencing revealed three novel...... polymorphisms. Finally, the AIRE copy number was determined by duplex quantitative PCR in 14 patients with APS I, 161 patients with AAD and APS II and in 39 healthy subjects. In two Scandinavian APS I patients previously reported to be homozygous for common AIRE mutations, we identified large deletions...

  2. Planck stars

    CERN Document Server

    Rovelli, Carlo

    2014-01-01

    A star that collapses gravitationally can reach a further stage of its life, where quantum-gravitational pressure counteracts weight. The duration of this stage is very short in the star proper time, yielding a bounce, but extremely long seen from the outside, because of the huge gravitational time dilation. Since the onset of quantum-gravitational effects is governed by energy density --not by size-- the star can be much larger than planckian in this phase. The object emerging at the end of the Hawking evaporation of a black hole can can then be larger than planckian by a factor $(m/m_{\\scriptscriptstyle P})^n$, where $m$ is the mass fallen into the hole, $m_{\\scriptscriptstyle P}$ is the Planck mass, and $n$ is positive. The existence of these objects alleviates the black-hole information paradox. More interestingly, these objects could have astrophysical and cosmological interest: they produce a detectable signal, of quantum gravitational origin, around the $10^{-14} cm$ wavelength.

  3. Analysis list: CASP8AP2 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available CASP8AP2 Digestive tract + hg19 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/CAS...P8AP2.1.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/CASP8AP2.5.tsv http://dbarchive.bi...osciencedbc.jp/kyushu-u/hg19/target/CASP8AP2.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/CAS

  4. Magnetic Fields and UV-line Variability in beta Cephei

    NARCIS (Netherlands)

    R.S. Schnerr; H.F. Henrichs; S.P. Owocki; A. ud-Doula; R.H.D. Townsend

    2007-01-01

    We present results of numerical simulations of wind variability in the magnetic B1 IVe star beta Cephei. 2D-MHD simulations are used to determine the structure of the wind. From these wind models we calculate line profiles for different aspect angles to simulate rotation. The results are compared wi

  5. The hot Gamma-Doradus and Maia stars

    CERN Document Server

    Balona, L A; Joshi, Yogesh C; Joshi, S; Sharma, K; Semenko, E; Pandey, G; Chakradhari, N K; Mkrtichian, David; Hema, B P; Nemec, J M

    2016-01-01

    The hot $\\gamma$~Doradus stars have multiple low frequencies characteristic of $\\gamma$~Dor or SPB variables, but are located between the red edge of the SPB and the blue edge of the $\\gamma$~Dor instability strips where all low-frequency modes are stable in current models of these stars. Though $\\delta$~Sct stars also have low frequencies, there is no sign of high frequencies in hot $\\gamma$~Dor stars. We obtained spectra to refine the locations of some of these stars in the H-R diagram and conclude that these are, indeed, anomalous pulsating stars. The Maia variables have multiple high frequencies characteristic of $\\beta$~Cep and $\\delta$~Sct stars, but lie between the red edge of the $\\beta$~Cep and the blue edge of the $\\delta$~Sct instability strips. We compile a list of all Maia candidates and obtain spectra of two of these stars. Again, it seems likely that these are anomalous pulsating stars which are currently not understood.

  6. Chemogenomic identification of Ref-1/AP-1 as a therapeutic target for asthma.

    Science.gov (United States)

    Nguyen, Cu; Teo, Jia-Ling; Matsuda, Akihisa; Eguchi, Masakatsu; Chi, Emil Y; Henderson, William R; Kahn, Michael

    2003-02-04

    Asthma is characterized by an oxidantantioxidant imbalance in the lungs leading to activation of redox-sensitive transcription factors, nuclear factor kappaB (NF-kappaB), and activator protein-1 (AP-1). To develop therapeutic strategies for asthma, we used a chemogenomics approach to screen for small molecule inhibitor(s) of AP-1 transcription. We developed a beta-strand mimetic template that acts as a reversible inhibitor (pseudosubstrate) of redox proteins. This template incorporates an enedione moiety to trap reactive cysteine nucleophiles in the active sites of redox proteins. Specificity for individual redox factors was achieved through variations in X and Y functionality by using a combinatorial library approach. A limited array (2 x 6) was constructed where X was either NHCH(3) or NHCH(2) Ph and Y was methyl, phenyl, m-cyanophenyl, m-nitrophenyl, m-acetylaniline, or m-methylbenzoate. These analogs were evaluated for their ability to inhibit transcription in transiently transfected human lung epithelial A549 cells from either an AP-1 or NF-kappaB reporter. A small-molecule inhibitor, PNRI-299, was identified that selectively inhibited AP-1 transcription (IC(50) of 20 microM) without affecting NF-kappaB transcription (up to 200 microM) or thioredoxin (up to 200 microM). The molecular target of PNRI-299 was determined to be the oxidoreductase, redox effector factor-1 by an affinity chromatography approach. The selective redox effector factor-1 inhibitor, PNRI-299, significantly reduced airway eosinophil infiltration, mucus hypersecretion, edema, and IL-4 levels in a mouse asthma model. These data validate AP-1 as an important therapeutic target in allergic airway inflammation.

  7. Star formation history in forming dwarf galaxies

    Science.gov (United States)

    Berczik, P.; Kravchuk, S. G.

    The processes of formation and evolution of isolated dwarf galaxies over the Hubble timescale is followed by means of SPH techniques. As an initial protogalaxy perturbation we consider an isolated, uniform, solid -- body rotated sphere involved into the Hubble flow and made of dark and baryonic matter in a 10:1 ratio. The simulations are carried out for the set of models having spin parameters lambda in the range from 0.01 to 0.08 and the total mass of dark matter 1011 M_odot . Our model includes gasdynamics, radiative processes, star formation, supernova feedback and simplified chemistry. The application of modified star formation criterion which accounts for chaotic motions and the time lag between initial development of suitable conditions for star formation and star formation itself (Berczik P.P, Kravchuk S.G. 1997, Ap.Sp.Sci.) provides the realistic description of the process of galaxy formation and evolution. Two parameters: total mass and initial angular momentum of the dwarf protogalaxy play the crucial role in its star formation activity. After the 15 Gyr of the evolution the rapidly rotated dwarf galaxies manifest themselves as an extremly gasrich, heavy element deficient objects showing the initial burst of star formation activity in several spatially separated regions. Slowly rotating objects manifest themselves finally as typical evolved dwarf galaxies.

  8. Destruction of a Magnetized Star

    Science.gov (United States)

    Kohler, Susanna

    2017-01-01

    completely.Amplifying EncountersFor stars that survive their encounter with the black hole, Guillochon and McCourt find that the process of partial disruption and re-accretion can amplify the magnetic field of the star by up to a factor of 20. Repeated encounters of the star with the black hole could amplify the field even more.The authors suggest an interesting implication of this idea: a population of highly magnetized stars may have formed in our own galactic center, resulting from their encounters with the supermassive black hole Sgr A*.A turbulent magnetic field forms after a partial stellar disruption and re-accretion of the tidal tails. [Adapted from Guillochon McCourt 2017]Effects in DestructionFor stars that are completely shredded and form a tidal stream after their encounter with the black hole, the authors find that the magnetic field geometry straightens within the stream of debris. There, the pressure of the magnetic field eventually dominates over the gas pressure and self-gravity.Guillochon and McCourt find that the fields new configuration isnt ideal for powering jets from the black hole but it is strong enough to influence how the stream interacts with itself and its surrounding environment, likely affecting what we can expect to see from these short-lived events.These simulations have clearly demonstrated the need to further explore the role of magnetic fields in the disruptions of stars by black holes.BonusCheck out the full (brief) video from one of the simulations by Guillochon and McCourt (be sure to watch it in high-res!). It reveals the evolution of a stars magnetic field configuration as the star is partially disrupted by the forces of a supermassive black hole and then re-accretes.CitationJames Guillochon and Michael McCourt 2017 ApJL 834 L19. doi:10.3847/2041-8213/834/2/L19

  9. When stars collide

    NARCIS (Netherlands)

    Glebbeek, E.; Pols, O.R.

    2007-01-01

    When two stars collide and merge they form a new star that can stand out against the background population in a star cluster as a blue straggler. In so called collision runaways many stars can merge and may form a very massive star that eventually forms an intermediate mass blackhole. We have perfor

  10. Measure of the stars

    Energy Technology Data Exchange (ETDEWEB)

    Henbest, N.

    1984-12-13

    The paper concerns the Hertzsprung-Russel (H-R) diagram, which is graph relating the brightness to the surface temperature of the stars. The diagram provides a deep insight into the fundamental properties of the stars. Evolution of the stars; the death of a star; distances; and dating star clusters, are all briefly discussed with reference to the H-R diagram.

  11. AP600 containment purge radiological analysis

    Energy Technology Data Exchange (ETDEWEB)

    O`Connor, M.; Schulz, J.; Tan, C. [Bechtel Power Corporation (United States)] [and others

    1995-02-01

    The AP600 Project is a passive pressurized water reactor power plant which is part of the Design Certification and First-of-a-Kind Engineering effort under the Advanced Light Water Reactor program. Included in this process is the design of the containment air filtration system which will be the subject of this paper. We will compare the practice used by previous plants with the AP600 approach to meet the goals of industry standards in sizing the containment air filtration system. The radiological aspects of design are of primary significance and will be the focus of this paper. The AP600 Project optimized the design to combine the functions of the high volumetric flow rate, low volumetric flow rate, and containment cleanup and other filtration systems into one multi-functional system. This achieves a more simplified, standardized, and lower cost design. Studies were performed to determine the possible concentrations of radioactive material in the containment atmosphere and the effectiveness of the purge system to keep concentrations within 10CFR20 limits and within offsite dose objectives. The concentrations were determined for various reactor coolant system leakage rates and containment purge modes of operation. The resultant concentrations were used to determine the containment accessibility during various stages of normal plant operation including refueling. The results of the parametric studies indicate that a dual train purge system with a capacity of 4,000 cfm per train is more than adequate to control the airborne radioactivity levels inside containment during normal plant operation and refueling, and satisfies the goals of ANSI/ANS-56.6-1986 and limits the amount of radioactive material released to the environment per ANSI/ANS 59.2-1985 to provide a safe environment for plant personnel and offsite residents.

  12. The Significance of Anti-Beta-2-Glycoprotein I Antibodies in Antiphospholipid Syndrome

    Directory of Open Access Journals (Sweden)

    Anna Brusch

    2016-06-01

    Full Text Available Antiphospholipid syndrome (APS is a thrombophilic disorder that classically presents with vascular thrombosis and/or obstetric complications. APS is associated with antiphospholipid antibodies: a heterogeneous group of autoantibodies that are directed against membrane phospholipids in complex with phospholipid-binding proteins. Beta-2-glycoprotein I (B2GPI binds anionic phospholipids and is considered to be the predominant antigen in APS and antibodies against B2GPI (anti-B2GPI are recognised in the laboratory criteria for APS diagnosis. This review focuses on the part played by anti-B2GPI in the pathogenesis of APS, their associations with different clinical phenotypes of the disorder and new avenues for refining the diagnostic potential of anti-B2GPI testing.

  13. Betting against Beta

    DEFF Research Database (Denmark)

    Frazzini, Andrea; Heje Pedersen, Lasse

    2014-01-01

    We present a model with leverage and margin constraints that vary across investors and time. We find evidence consistent with each of the model's five central predictions: (1) Because constrained investors bid up high-beta assets, high beta is associated with low alpha, as we find empirically for......, the return of the BAB factor is low. (4) Increased funding liquidity risk compresses betas toward one. (5) More constrained investors hold riskier assets....... for US equities, 20 international equity markets, Treasury bonds, corporate bonds, and futures. (2) A betting against beta (BAB) factor, which is long leveraged low-beta assets and short high-beta assets, produces significant positive risk-adjusted returns. (3) When funding constraints tighten...

  14. Betting Against Beta

    DEFF Research Database (Denmark)

    Frazzini, Andrea; Heje Pedersen, Lasse

    We present a model with leverage and margin constraints that vary across investors and time. We find evidence consistent with each of the model’s five central predictions: (1) Since constrained investors bid up high-beta assets, high beta is associated with low alpha, as we find empirically for U...... of the BAB factor is low; (4) Increased funding liquidity risk compresses betas toward one; (5) More constrained investors hold riskier assets........S. equities, 20 international equity markets, Treasury bonds, corporate bonds, and futures; (2) A betting-against-beta (BAB) factor, which is long leveraged low beta assets and short high-beta assets, produces significant positive risk-adjusted returns; (3) When funding constraints tighten, the return...

  15. Ozone mitigation tests at the APS

    Energy Technology Data Exchange (ETDEWEB)

    Kuzay, T.M.; Collins, J.T.; Pisharody, M.; Job, P.K.; Wang Zhibi

    1996-09-01

    Ozone is generated in the APS experimental stations whenever the x-ray beam has a chance to interact with air. Ozone concentrations in an experimental station have to be below a certain defined limit (current OSHA regulations specify 0.08 ppm as the maximum limit) before an experimenter can reenter the hutch. This limit is said to be currently under study for a downward adjustment. One method of depleting the ozone generated in an experimental station is mitigation through either adsorption or direct destruction. In recent tests, both methods were tried using commercially available units. Test results and some analytical predictions are presented.

  16. Wiley AP english language and composition

    CERN Document Server

    Woods, Geraldine

    2013-01-01

    Two full-length practice tests to help you score your highest Review questions with complete answers and explanations for the most popular themes on the test Study strategies and expert test-taking tips to keep you calm and focused on test day Review key exam topics and themes to maximize your score Preparing for the AP English Language and Composition test? This test-prep guide helps you perfect the skills you need to achieve your best possible score. You'll find winning test-taking tips, multiple-choice strategies, and essay guidelines, as well as great advice on getting the

  17. Imperfect World of $\\beta\\beta$-decay Nuclear Data Sets

    CERN Document Server

    Pritychenko, B

    2015-01-01

    The precision of double-beta ($\\beta\\beta$) decay experimental half lives and their uncertainties is reanalyzed. The method of Benford's distributions has been applied to nuclear reaction, structure and decay data sets. First-digit distribution trend for $\\beta\\beta$-decay T$_{1/2}^{2\

  18. Catalog of averaged magnetic phase curves of stars

    CERN Document Server

    Bychkov, V D; Madej, J

    2016-01-01

    The second version of the catalog contains information about 275 stars of different types. During the time that has elapsed since the creation of the first catalog, situation fundamentally changed primarily due to the significant increase of accuracy of magnetic fields (MF) measurements. Up to now global magnetic field were discoverd and measured in stars of many types and their behavior partially was studied. Magnetic behavior of Ap Bp stars is the most thoroughly studied. The catalog contains information about 182 such objects. The main goals for the construction of the catalog are: 1. Review and summarize our kowledge about magnetic behavior of different types of stars. 2. The whole data are uniformly presented and processed which will allow one to perform statistical analysis of the variability of the (longitudinal) magnetic fields of stars. 3. The informations are presented in the most convenient form for testing different theoretical models of different kind. 4. The catalog will be useful for the develo...

  19. Equation of State of Protoneutron Star with Trapped Neutrinos

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hua; JIA Huan-Yu

    2006-01-01

    The influence of trapped neutrinos on the proto-neutron star is studied in the framework of relativistic mean-field theory. The results show that trapped neutrinos increase proton fraction and make the equation of state of neutron star matter softer when neglecting hyperonic freedom, while suppress the appearance of hyperons and make the equation of state stiffer when including hyperons in the protoneutron star. The maximum mass, compared with cold neutron star which is in beta equilibrium, decreases by 0.06M☉ for non-strange protoneutron star while increases by 0.21M☉ for protoneutron star with hyperons when the relative number of trapped neutrino is 0.4.

  20. The Electronic ApJ in Context

    Science.gov (United States)

    Biemesderfer, C. D.

    1995-12-01

    The on-line edition of the Astrophysical Journal provides the first opportunity for astronomical researchers to interact with the literature in a network context. Other electronic journals will follow. Astronomers will continue to develop ways to take advantage of information on the network, and these will be most effective when ApJ articles, observations from data centers, proposals for telescope time, communications with collaborators, and so on, are meshed. Astronomical literature, as a resource on the Internet, is not unique from the viewpoint of function or management, and astronomers are not unique as scholars in their desire to use the Internet as a tool to advance their work. We need to ensure as a community that all our resources for research --- journals and data --- fit in a global context on an Internet being used by everyone. In other words, we have to be sure that the ApJ fits into all the digital libraries of the future, including the ones we don't build. This paper will present a scenario in which many varied forms of information, astronomical and otherwise, can be catalogued and distributed so that they can be discovered and used by the research community.

  1. SN 2005ap: A Most Brilliant Explosion

    CERN Document Server

    Quimby, Robert M; Wheeler, J Craig; Höflich, Peter; Akerlof, Carl W; Rykoff, Eli S

    2007-01-01

    We present unfiltered photometric observations with ROTSE-III and optical spectroscopic follow-up with the HET and Keck of the most luminous supernova yet identified, SN 2005ap. The spectra taken about 3 days before and 6 days after maximum light show narrow emission lines (likely originating in the dwarf host) and absorption lines at a redshift of z=0.2832, which puts the peak unfiltered magnitude at -22.7 +/- 0.1 absolute. Broad P-Cygni features corresponding to H-alpha, CIII, NIII, and OIII, are further detected with a photospheric velocity of ~20,000 km/s. Unlike other highly luminous supernovae such as 2006gy and 2006tf that show slow photometric evolution, the light curve of SN 2005ap indicates a 1-3 week rise to peak followed by a relatively rapid decay. The spectra also lack the distinct emission peaks from moderately broadened (FWHM ~ 2,000 km/s) Balmer lines seen in SN 2006gy and SN 2006tf. We briefly discuss the origin of the extraordinary luminosity from a strong interaction as may be expected fro...

  2. THE INITIAL MASS FUNCTION MODELED BY A LEFT TRUNCATED BETA DISTRIBUTION

    Energy Technology Data Exchange (ETDEWEB)

    Zaninetti, Lorenzo, E-mail: zaninetti@ph.unito.it [Dipartimento di Fisica, Via Pietro Giuria 1, I-10125 Torino (Italy)

    2013-03-10

    The initial mass function for stars is usually fitted by three straight lines, which means it has seven parameters. The presence of brown dwarfs (BDs) increases the number of straight lines to four and the number of parameters to nine. Another common fitting function is the lognormal distribution, which is characterized by two parameters. This paper is devoted to demonstrating the advantage of introducing a left truncated beta probability density function, which is characterized by four parameters. The constant of normalization, the mean, the mode, and the distribution function are calculated for the left truncated beta distribution. The normal beta distribution that results from convolving independent normally distributed and beta distributed components is also derived. The chi-square test and the Kolmogorov-Smirnov test are performed on a first sample of stars and BDs that belongs to the massive young cluster NGC 6611, and on a second sample that represents the masses of the stars of the cluster NGC 2362.

  3. The initial mass function modeled by a left truncated beta distribution

    CERN Document Server

    Zaninetti, L

    2013-01-01

    The initial mass function (IMF) for the stars is usually fitted by three straight lines, which means seven parameters. The presence of brown dwarfs (BD) increases to four the straight lines and to nine the parameters. Another common fitting function is the lognormal distribution, which is characterized by two parameters. This paper is devoted to demonstrating the advantage of introducing a left truncated beta probability density function, which is characterized by four parameters. The constant of normalization, the mean, the mode and the distribution function are calculated for the left truncated beta distribution. The normal-beta (NB) distribution which results from convolving independent normally distributed and beta distributed components is also derived. The chi-square test and the K-S test are performed on a first sample of stars and BDs which belongs to the massive young cluster NGC 6611 and on a second sample which represents the star's masses of the cluster NGC 2362.

  4. Disrupted Stars in Unusual Galaxies

    Science.gov (United States)

    Kohler, Susanna

    2016-03-01

    galaxies on average, yet includes the hosts of 75% of the TDEs.This means that quiescent galaxies with strong past star formation are overrepresented in the TDE host galaxy sample by a factor of ~190 times. Quiescent galaxies with at least moderately strong past star formation are overrepresented among TDE hosts by a factor of ~33.Why the Preference?So why might these galaxies so frequently host TDEs? The authors propose an idea: many of these galaxies may have experienced recent galaxygalaxy mergers. Such a mergercould trigger a burst of star formation, perturb stellar orbits, and then eventually settle into a quiescent state with stars that are more likely to be centrally concentrated and with orbits that might lead them to pass close to the central black hole(s).Future observations of more TDEs will certainly help to further evaluate this trend. But the current data certainly implies that TDEs are discriminating in their choice of host, providing interesting clues about the mechanisms driving their rates.CitationK. Decker French et al 2016 ApJ 818 L21. doi:10.3847/2041-8205/818/1/L21

  5. Trichomonas vaginalis: the adhesins AP51 and AP65 bind heme and hemoglobin.

    Science.gov (United States)

    Ardalan, Shahed; Lee, B Craig; Garber, Gary E

    2009-04-01

    Trichomonas vaginalis is the cause of human trichomoniasis, the most common non-viral sexually transmitted disease worldwide. Although acquisition of iron by binding to host hemoglobin through distinct receptor(s) has been described, no specific heme- or hemoglobin-binding site has been reported in this parasite. To determine the presence of hemoglobin-binding protein(s), membrane proteins were subjected to hemoglobin-affinity chromatography. Eluted proteins were analysed by SDS-PAGE. Two protein bands of 48 and 63 kDa were detected. Competition assay with an excess amount of hemoglobin or hemin in hemoglobin-affinity chromatography could block the 63- and 48-kDa bands, respectively. Further analysis by mass spectrometry indicated that the 48- and 63-kDa proteins had identity with two T. vaginalis adhesins: AP51 and AP65, respectively. This study confirms the existence of multifunctional proteins in T. vaginalis, and suggested that AP51 and AP65, besides serving as adhesion molecules, could also act as heme- and hemoglobin-binding proteins.

  6. AP1000进度管理研究%The study on AP1000 Schedule management

    Institute of Scientific and Technical Information of China (English)

    李阳; 王飞鸣

    2015-01-01

    核电建设进度管理非常重要,本文针对核电站进度管理的内容、体系、管理方式等进行介绍,并结合AP1000核电技术的特点——模块化,分析其对进度管理的影响和目前存在的问题。并结合影响和问题提出了在后续AP1000建设进度管理中的几项建议。%Nuclear power plant construction progress management is very important. This paper addresses important topics including the content, system and manage methods of nuclear power plants construction. Combining the characteristics of AP1000 nuclear power technology-modular, the paper analyzed its impact on progress management and the existing problems. Depending on the impacts and problems, the paper also raised several suggestions in AP1000 modular construction.

  7. Negative Beta Encoder

    CERN Document Server

    Kohda, Tohru; Aihara, Kazuyuki

    2008-01-01

    A new class of analog-digital (A/D), digital-analog (D/A) converters as an alternative to conventional ones, called $\\beta$-encoder, has been shown to have exponential accuracy in the bit rates while possessing self-correction property for fluctuations of amplifier factor $\\beta$ and quantizer threshold $\

  8. Double beta decay experiments

    CERN Document Server

    Barabash, A S

    2011-01-01

    The present status of double beta decay experiments is reviewed. The results of the most sensitive experiments are discussed. Proposals for future double beta decay experiments with a sensitivity to the $$ at the level of (0.01--0.1) eV are considered.

  9. Genetics Home Reference: beta thalassemia

    Science.gov (United States)

    ... Understand Genetics Home Health Conditions beta thalassemia beta thalassemia Enable Javascript to view the expand/collapse boxes. Download PDF Open All Close All Description Beta thalassemia is a blood disorder that reduces the production ...

  10. Enigma of Runaway Stars Solved

    Science.gov (United States)

    1997-01-01

    . In fact, this is one of the most `perfect' bow shocks of parabolic form ever observed around an OB-runaway. Moreover, the orientation of the bow shock indicates that the system is moving towards the north; its origin must therefore lie somewhere south of its present position in the sky. It also turns out that the accordingly deduced path of HD77581 crosses a well-known OB-association with the designation Vel OB1 . At the measured distance of Vel OB1 of about 6000 lightyears, the observed proper motion and radial velocity of HD77581 indicate a space velocity of 90 km/sec. With this velocity, it would have taken HD77581 and its compact companion about 2.5 million years to travel the distance between Vel OB1 and its present position. This corresponds exactly to the expected time that has passed since the supernova explosion of the progenitor star of Vela~X-1, as deduced from the observed properties of the binary system. The puzzle comes together Now everything fits! The observation of a bow shock around the OB star HD77581 and its compact companion Vela X-1 supports the scenario originally proposed by Blaauw to create OB-runaway stars by the supernova explosion of the binary companion. Following back the path of the system resulted in the discovery of the place where it was born and from where it escaped after the violent supernova explosion which produced the neutron star that now manifests itself as the strong X-ray source known as Vela X-1. More information about this research project This research project is described in ESO Preprint no.~1199 and will appear shortly as a Letter to the Editor in `Astrophysical Journal' (ApJ 475, L37-L40). Notes: [1] Professor Adriaan Blaauw is a well-known Dutch astronomer (Leiden and Groningen). He participated very actively in the build-up of ESO in the 1950's and 60's and he was ESO Director General from 1970 - 1974. He is the author of ` ESO's Early History - The European Southern Observatory from concept to reality ' (1991). [2

  11. An international multicentre-laboratory evaluation of a new assay to detect specifically lupus anticoagulants dependent on the presence of anti-beta2-glycoprotein autoantibodies

    NARCIS (Netherlands)

    de laat, B.; Derksen, R. H. W. M.; Reber, G.; Musial, J.; Swadzba, J.; Bozic, B.; Cucnik, S.; Regnault, V.; Forastiero, R.; Woodhams, B. J.; de Groot, Ph. G.

    2011-01-01

    Background: Antiphospholipid syndrome (APS) is diagnosed by the simultaneous presence of vascular thrombosis and/or pregnancy morbidity and detection of antiphospholipid antibodies in plasma. Objectives: We have shown that prolongation of clotting time by anti-beta2-glycoprotein I (beta2GPI) antibod

  12. Antiphospholipid antibodies promote leukocyte-endothelial cell adhesion and thrombosis in mice by antagonizing eNOS via beta 2GPI and apoER2

    NARCIS (Netherlands)

    Ramesh, Sangeetha; Morrell, Craig N.; Tarango, Cristina; Thomas, Gail D.; Yuhanna, Ivan S.; Girardi, Guillermina; Herz, Joachim; Urbanus, Rolf T.; de Groot, Philip G.; Thorpe, Philip E.; Salmon, Jane E.; Shaul, Philip W.; Mineo, Chieko

    2011-01-01

    In antiphospholipid syndrome (APS), antiphospholipid antibodies (aPL) binding to beta 2 glycoprotein I (beta 2GPI) induce endothelial cell-leukocyte adhesion and thrombus formation via unknown mechanisms Here we show that in mice both of these processes are caused by the inhibition of eNOS In studie

  13. BETA-AMYLOID((1-42)) AFFECTS CHOLINERGIC BUT NOT PARVALBUMIN-CONTAINING NEURONS IN THE SEPTAL COMPLEX OF THE RAT

    NARCIS (Netherlands)

    HARKANY, T; DEJONG, GI; SOOS, K; PENKE, B; LUITEN, PGM; GULYA, K

    1995-01-01

    beta-Amyloid((1-42)) peptide (beta AP((1-42))) was injected into the medial septum of rats. After a 14-day survival time, neuronal alterations in the septal cholinergic and GABAergic systems were visualized by means of histo- and immunocytochemical methods. Neurons insulted by the peptide were prima

  14. Rapid synthesis of beta zeolites

    Science.gov (United States)

    Fan, Wei; Chang, Chun -Chih; Dornath, Paul; Wang, Zhuopeng

    2015-08-18

    The invention provides methods for rapidly synthesizing heteroatom containing zeolites including Sn-Beta, Si-Beta, Ti-Beta, Zr-Beta and Fe-Beta. The methods for synthesizing heteroatom zeolites include using well-crystalline zeolite crystals as seeds and using a fluoride-free, caustic medium in a seeded dry-gel conversion method. The Beta zeolite catalysts made by the methods of the invention catalyze both isomerization and dehydration reactions.

  15. UV habitable zones around M stars

    Science.gov (United States)

    Buccino, Andrea P.; Lemarchand, Guillermo A.; Mauas, Pablo J. D.

    2007-12-01

    During the last decade there was a change in paradigm, which led to consider that terrestrial-type planets within liquid-water habitable zones (LW-HZ) around M stars can also be suitable places for the emergence and evolution of life. Since many dMe stars emit large amount of UV radiation during flares, in this work we analyze the UV constrains for living systems on Earth-like planets around dM stars. We apply our model of UV habitable zone (UV-HZ; Buccino, A.P., Lemarchand, G.A., Mauas, P.J.D., 2006. Icarus 183, 491-503) to the three planetary systems around dM stars (HIP 74995, HIP 109388 and HIP 113020) observed by IUE and to two M-flare stars (AD Leo and EV Lac). In particular, HIP 74995 hosts a terrestrial planet in the LW-HZ, which is the exoplanet that most resembles our own Earth. We show, in general, that during the quiescent state there would not be enough UV radiation within the LW-HZ to trigger the biogenic processes and that this energy could be provided by flares of moderate intensity, while strong flares do not necessarily rule-out the possibility of life-bearing planets.

  16. A Four-Star Lightweight

    Science.gov (United States)

    Kohler, Susanna

    2015-10-01

    least 1,800 AU which means that, if the system is only a few million years old, the binary pairs have orbited each other no more than ~20 times.The authors measurements show that the first binary pair (labeled Aab, where Aa and Ab are the two stars) consists of a 200 MJup low-mass star and a 35 MJup brown dwarf. The second binary pair (Bab) consists of a 19 MJup brown dwarf and a ~10 MJup companion. This gives 2M0441+2301 AabBab a total mass of only ~0.26 solar masses, making it the lowest-mass quadruple system yet discovered.The hierarchical structure of this system strongly suggests that it formed from the collapse and fragmentation of a molecular cloud core. What makes this system especially interesting is the span of masses involved. The low mass of the companion in Bab indicates that its possible to form planetary-mass companions from a cloud-fragmentation pathway which suggests that this may also be legitimate channel to consider for the formation of massive exoplanets.Note: article edited to more accurately reflect the specific contributions of this study.CitationBrendan P. Bowler and Lynne A. Hillenbrand 2015 ApJ 811 L30. doi:10.1088/2041-8205/811/2/L30

  17. Identifying CEMP-s and CEMP-no Stars within Milky Way Halo Structures

    Science.gov (United States)

    Dietz, Sarah Eliana; Beers, Timothy C.; Carollo, Daniela; Yoon, Jinmi; Placco, Vinicius M.

    2017-01-01

    Carbon-enhanced metal-poor (CEMP) stars are ancient objects used to probe the star-formation history of the first generations of stars in the Galactic halo. CEMP stars may be further separated into sub-classes based on the presence or absence of heavy elements associated with different neutron-capture processes. Here we examine CEMP stars enriched with the nucleosynthesis products of the slow neutron-capture process (CEMP-s stars) and those that exhibit no strong neutron-capture element enrichments (CEMP-no stars), which are preferentially found in the Galaxy’s inner and outer halo regions, respectively [1,2].Recent structure-finding algorithms have been applied to samples of K giants from SDSS to identify groups of associated stars and classify them as members of known structures, such as the Sagittarius tidal debris stream [3]. Here we investigate whether CEMP-s and CEMP-no stars are associated in different proportion with such structures or with the diffuse halo. We distinguish CEMP-s stars from CEMP-no stars using metallicity ([Fe/H]) and carbonicity ([C/Fe]), a method that has been demonstrated to be as effective as separation based on the presence of Ba enhancements used in the past [4]. We discuss the impact of our results on our understanding of the nature of CEMP stars and their progenitor populations, as well as on the assembly history of the Milky Way.This work received partial support from PHY 14-30152; Physics Frontier Center/JINA Center for the Evolution of the Elements (JINA-CEE), awarded by the US National Science Foundation.References:[1] Carollo, D. et al. 2007, Nature, 450, 1020[2] Carollo, D. et al. 2010, ApJ, 712, 692[3] Janesh, W. et al. 2016, ApJ, 816, 80[4] Yoon, J. et al. 2016, ApJ, in press (arXiv:1607.06336)

  18. Can strange stars mimic dark energy stars?

    CERN Document Server

    Deb, Debabrata; Guha, B K; Ray, Saibal

    2016-01-01

    The possibility of strange stars mixed with dark energy to be one of candidates for dark energy stars is the main issue of the present study. Our investigation shows that quark matter is acting as dark energy after certain yet unknown critical condition inside the quark stars. Our proposed model reveals that strange stars mixed with dark energy feature not only a physically acceptable stable model but also mimic characteristics of dark energy stars. The plausible connections are shown through the mass-radius relation as well as the entropy and temperature. We particulary note that two-fluid distribution is the major reason for anisotropic nature of the spherical stellar system.

  19. Low Earth orbit assessment of proton anisotropy using AP8 and AP9 trapped proton models

    Science.gov (United States)

    Badavi, Francis F.; Walker, Steven A.; Santos Koos, Lindsey M.

    2015-04-01

    The completion of the International Space Station (ISS) in 2011 has provided the space research community with an ideal evaluation and testing facility for future long duration human activities in space. Ionized and secondary neutral particles radiation measurements inside ISS form the ideal tool for validation of radiation environmental models, nuclear reaction cross sections and transport codes. Studies using thermo-luminescent detectors (TLD), tissue equivalent proportional counter (TPEC), and computer aided design (CAD) models of early ISS configurations confirmed that, as input, computational dosimetry at low Earth orbit (LEO) requires an environmental model with directional (anisotropic) capability to properly describe the exposure of trapped protons within ISS. At LEO, ISS encounters exposure from trapped electrons, protons and geomagnetically attenuated galactic cosmic rays (GCR). For short duration studies at LEO, one can ignore trapped electrons and ever present GCR exposure contributions during quiet times. However, within the trapped proton field, a challenge arises from properly estimating the amount of proton exposure acquired. There exist a number of models to define the intensity of trapped particles. Among the established trapped models are the historic AE8/AP8, dating back to the 1980s and the recently released AE9/AP9/SPM. Since at LEO electrons have minimal exposure contribution to ISS, this work ignores the AE8 and AE9 components of the models and couples a measurement derived anisotropic trapped proton formalism to omnidirectional output from the AP8 and AP9 models, allowing the assessment of the differences between the two proton models. The assessment is done at a target point within the ISS-11A configuration (circa 2003) crew quarter (CQ) of Russian Zvezda service module (SM), during its ascending and descending nodes passes through the south Atlantic anomaly (SAA). The anisotropic formalism incorporates the contributions of proton narrow

  20. Low Earth orbit assessment of proton anisotropy using AP8 and AP9 trapped proton models.

    Science.gov (United States)

    Badavi, Francis F; Walker, Steven A; Santos Koos, Lindsey M

    2015-04-01

    The completion of the International Space Station (ISS) in 2011 has provided the space research community with an ideal evaluation and testing facility for future long duration human activities in space. Ionized and secondary neutral particles radiation measurements inside ISS form the ideal tool for validation of radiation environmental models, nuclear reaction cross sections and transport codes. Studies using thermo-luminescent detectors (TLD), tissue equivalent proportional counter (TPEC), and computer aided design (CAD) models of early ISS configurations confirmed that, as input, computational dosimetry at low Earth orbit (LEO) requires an environmental model with directional (anisotropic) capability to properly describe the exposure of trapped protons within ISS. At LEO, ISS encounters exposure from trapped electrons, protons and geomagnetically attenuated galactic cosmic rays (GCR). For short duration studies at LEO, one can ignore trapped electrons and ever present GCR exposure contributions during quiet times. However, within the trapped proton field, a challenge arises from properly estimating the amount of proton exposure acquired. There exist a number of models to define the intensity of trapped particles. Among the established trapped models are the historic AE8/AP8, dating back to the 1980s and the recently released AE9/AP9/SPM. Since at LEO electrons have minimal exposure contribution to ISS, this work ignores the AE8 and AE9 components of the models and couples a measurement derived anisotropic trapped proton formalism to omnidirectional output from the AP8 and AP9 models, allowing the assessment of the differences between the two proton models. The assessment is done at a target point within the ISS-11A configuration (circa 2003) crew quarter (CQ) of Russian Zvezda service module (SM), during its ascending and descending nodes passes through the south Atlantic anomaly (SAA). The anisotropic formalism incorporates the contributions of proton narrow

  1. Proximal femoral canal shape is more accurately assessed on AP hip radiographs than AP pelvis radiographs in primary hip osteoarthritis.

    Science.gov (United States)

    Merle, Christian; Waldstein, Wenzel; Gregory, Jennifer S; Goodyear, Simon R; Aspden, Richard M; Aldinger, Peter R; Murray, David W; Gill, Harinderjit S

    2013-01-01

    The objectives of the present study were to determine whether differences in the radiographic appearance of the of the proximal femoral canal exist on corresponding AP pelvis and AP hip radiographs, and whether radiographic assessment of canal shape is accurate with reference to computed tomography (CT). In a retrospective study, corresponding radiographs and CT scans of 100 consecutive patients with primary hip OA were evaluated. Active shape modelling (ASM) was performed to assess the variation in proximal femoral canal shape and to identify differences between AP hip and AP pelvis views. Differences in the medial cortical flare between radiographs and CT were quantified using least squares curve fitting. ASM identified significant differences in the assessment of canal shape on corresponding AP hip and AP pelvis views. Curve fitting demonstrated a good agreement between AP hip radiographs and CT. Agreement between AP pelvis radiographs and CT was less good. In contrast to AP pelvis radiographs, AP hip radiographs allow a more accurate and reliable assessment of proximal femoral canal shape in the frontal plane in primary hip OA. Our findings may improve stem fit in total hip arthroplasty without the routine use of CT.

  2. B-type stars in eclipsing binaries

    Science.gov (United States)

    Ratajczak, Milena; Pigulski, Andrzej

    2016-07-01

    B-type stars in eclipsing binary systems are unique astrophysical tools to test several aspects of stellar evolution. Such objects can be used e.g. to determine the masses of Beta Cephei variable stars, as well as help to place tighter constraints on the value of the convective core overshooting parameter α. Both precise photometry and high-resolution spectroscopy with high SNR are required to achieve these goals, but since many of the targets are bright enough, the challenge is fair. Following this assumption, we shall explain how we plan to examine both the aforementioned aspects of stellar evolution using observations of B-type stars obtained with a wide range of spectrographs, as well as BRITE-Constellation satellites.

  3. Lifestyles of the Stars.

    Science.gov (United States)

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

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

  4. Modeling Navigation System Performance of a Satellite-Observing Star Tracker Tightly Integrated with an Inertial Measurement Unit

    Science.gov (United States)

    2015-03-26

    Hancock, R.C. Stirbl, and B. Pain. “ Active pixel sensor (APS) based star tracker ”. Aerospace Conference, 1998 IEEE, volume 1, 119–127 vol.1. 1998...Modeling Navigation System Performance of a Satellite-Observing Star Tracker Tightly Integrated with an Inertial Measurement Unit DISSERTATION Scott...Navigation System Performance of a Satellite-Observing Star Tracker Tightly Integrated with an Inertial Measurement Unit DISSERTATION Presented to the

  5. VizieR Online Data Catalog: C/O and Mg/Si for solar neighborhood's stars (Brewer+, 2016)

    Science.gov (United States)

    Brewer, J. M.; Fischer, D. A.

    2017-01-01

    The catalog of Brewer+ (2016, J/ApJS/225/32) has abundances of 15 elements, including C, O, Mg, and Si, for more than 1600 F, G, and K stars. The stars were all observed using the HIRES instrument on the Keck telescope with the same instrumental setup. Most of the stars were observed as part of the California Planet Search (CPS) program and have a typical S/N>>100. (1 data file).

  6. Circumnuclear Regions of Star Formation in Early Type Galaxies

    CERN Document Server

    Diaz, Angeles I; Hagele, Guillermo F; Castellanos, Marcelo

    2008-01-01

    Circumnuclear star forming regions, also called hotspots, are often found in the inner regions of some spiral galaxies where intense processes of star formation are taking place. In the UV, massive stars dominate the observed circumnuclear emission even in the presence of an active nucleus, contributing between 30 and 50% to the H$\\beta$ total emission of the nuclear zone. Spectrophotometric data of moderate resolution (3000 < R < 11000) are presented from which the physical properties of the ionized gas: electron density, oxygen abundances, ionization structure etc. have been derived.

  7. Project W-211, initial tank retrieval systems, description of operations for 241-AP-102 and 241-AP-104

    Energy Technology Data Exchange (ETDEWEB)

    RIECK, C.A.

    1999-02-25

    The primary purpose of the Initial Tank Retrieval Systems (ITRS) is to provide systems for retrieval of radioactive wastes stored in underground double-shell tanks (DSTS) for transfer to alternate storage, evaporation, pretreatment or treatment, while concurrently reducing risks associated with safety watch list and other DSTs. This Description of Operations (DOO) defines the control philosophy for the waste retrieval system for tanks 241-AP-102 (AP-102) and 241-AP-104 (AP-104). This DOO will provide a basis for the detailed design of the Retrieval Control System (RCS) for AP-102 and AP-104 and establishes test criteria for the RCS. The test criteria will be used during qualification testing and acceptance testing to verify operability.

  8. AP1000主系统先进性分析%The Progressiveness Analysis of the AP1000 Main System

    Institute of Scientific and Technical Information of China (English)

    李家杰

    2012-01-01

      本文总结了第三代先进非能动压水堆核电厂AP1000主系统的主要特点,对AP1000主系统的先进性进行了分析,核电厂主系统设计人员能够从该文中了解到 AP1000主系统与第二代核电厂主系统之间的差别。%  This paper summarizes the main features of the AP1000 main system of the third generation of advanced passive pressurized water reactor nuclear power plant , and analyzes the progressiveness of the AP1000 main system .From this paper, the main system designers of nuclear power factory can learn the difference between the second-generation nuclear power factory main system and AP1000 main system

  9. Neutrinoless double beta decay

    Indian Academy of Sciences (India)

    Kai Zuber

    2012-10-01

    The physics potential of neutrinoless double beta decay is discussed. Furthermore, experimental considerations as well as the current status of experiments are presented. Finally, an outlook towards the future, work on nuclear matrix elements and alternative processes is given.

  10. The Cambridge Double Star Atlas

    Science.gov (United States)

    MacEvoy, Bruce; Tirion, Wil

    2015-12-01

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

  11. Fênomeno de Raynaud grave associado a terapia com interferon-beta para esclerose múltipla: relato de caso Severe Raynaud's phenomenon associated with interferon-beta therapy for multiple sclerosis: case report

    Directory of Open Access Journals (Sweden)

    BORIS AFONSO CRUZ

    2000-06-01

    Full Text Available Interferon-B (IFN-beta é usado no tratamento de esclerose múltipla (EM. Descrevemos o caso de uma mulher com EM que apresentou fenômeno de Raynaud grave, livedo reticular e necrose digital duas semanas após tratamento com IFN-beta. Os sintomas melhoraram após suspensão do IFN-beta e início de anticoagulação associada a ciclofosfamida e corticóide. Fenômeno de Raynaud é um efeito colateral provável da terapia com IFN-beta para EM.Interferon-beta (IFN-beta is administered for treatment of multiple sclerosis (MS. We report on a woman with MS who presented with severe Raynaud's phenomenon, livedo-reticularis and digital necrosis two weeks after beginning therapy with IFN-beta. Symptoms improved after the IFN-beta was discontinued and anticoagulation associated with cyclophosphamide and corticoid were introduced. Raynaud's phenomenon is probably a side effect of IFN-beta therapy for multiple sclerosis.

  12. Alpha and Beta Determinations

    CERN Document Server

    Dunietz, Isard

    1999-01-01

    Because the Bd -> J/psi Ks asymmetry determines only sin(2 beta), a discrete ambiguity in the true value of beta remains. This note reviews how the ambiguity can be removed. Extractions of the CKM angle alpha are discussed next. Some of the methods require very large data samples and will not be feasible in the near future. In the near future, semi-inclusive CP-violating searches could be undertaken, which are reviewed last.

  13. Macrophage colony-stimulating factor augments beta-amyloid-induced interleukin-1, interleukin-6, and nitric oxide production by microglial cells.

    Science.gov (United States)

    Murphy, G M; Yang, L; Cordell, B

    1998-08-14

    In Alzheimer's disease (AD), a chronic cerebral inflammatory state is thought to lead to neuronal injury. Microglia, intrinsic cerebral immune effector cells, are likely to be key in the pathophysiology of this inflammatory state. We showed that macrophage colony-stimulating factor, a microglial activator found at increased levels in the central nervous system in AD, dramatically augments beta-amyloid peptide (betaAP)-induced microglial production of interleukin-1, interleukin-6, and nitric oxide. In contrast, granulocyte macrophage colony-stimulating factor, another hematopoietic cytokine found in the AD brain, did not augment betaAP-induced microglial secretory activity. These results indicate that increased macrophage colony-stimulating factor levels in AD could magnify betaAP-induced microglial inflammatory cytokine and nitric oxide production, which in turn could intensify the cerebral inflammatory state by activating astrocytes and additional microglia, as well as directly injuring neurons.

  14. Catalytic activity of nuclear PLC-beta(1) is required for its signalling function during C2C12 differentiation.

    Science.gov (United States)

    Ramazzotti, Giulia; Faenza, Irene; Gaboardi, Gian Carlo; Piazzi, Manuela; Bavelloni, Alberto; Fiume, Roberta; Manzoli, Lucia; Martelli, Alberto M; Cocco, Lucio

    2008-11-01

    Here we report that PLC-beta(1) catalytic activity plays a role in the increase of cyclin D3 levels and induces the differentiation of C2C12 skeletal muscle cells. PLC-beta(1) mutational analysis revealed the importance of His(331) and His(378) for the catalysis. The expression of PLC-beta(1) and cyclin D3 proteins is highly induced during the process of skeletal myoblast differentiation. We have previously shown that PLC-beta(1) activates cyclin D3 promoter during the differentiation of myoblasts to myotubes, indicating that PLC-beta(1) is a crucial regulator of the mouse cyclin D3 gene. We show that after insulin treatment cyclin D3 mRNA levels are lower in cells overexpressing the PLC-beta(1) catalytically inactive form in comparison to wild type cells. We describe a novel signalling pathway elicited by PLC-beta(1) that modulates AP-1 activity. Gel mobility shift assay and supershift performed with specific antibodies indicate that the c-jun binding site is located in a cyclin D3 promoter region specifically regulated by PLC-beta(1) and that c-Jun binding activity is significantly increased by insulin and PLC-beta(1) overexpression. Mutation of AP-1 site decreased the basal cyclin D3 promoter activity and eliminated its induction by insulin and PLC-beta(1). These results hint at the fact that PLC-beta(1) catalytic activity signals a c-jun/AP-1 target gene, i.e. cyclin D3, during myogenic differentiation.

  15. Magnetic fields in non-convective regions of stars

    Science.gov (United States)

    Braithwaite, Jonathan

    2017-01-01

    We review the current state of knowledge of magnetic fields inside stars, concentrating on recent developments concerning magnetic fields in stably stratified (zones of) stars, leaving out convective dynamo theories and observations of convective envelopes. We include the observational properties of A, B and O-type main-sequence stars, which have radiative envelopes, and the fossil field model which is normally invoked to explain the strong fields sometimes seen in these stars. Observations seem to show that Ap-type stable fields are excluded in stars with convective envelopes. Most stars contain both radiative and convective zones, and there are potentially important effects arising from the interaction of magnetic fields at the boundaries between them; the solar cycle being one of the better known examples. Related to this, we discuss whether the Sun could harbour a magnetic field in its core. Recent developments regarding the various convective and radiative layers near the surfaces of early-type stars and their observational effects are examined. We look at possible dynamo mechanisms that run on differential rotation rather than convection. Finally, we turn to neutron stars with a discussion of the possible origins for their magnetic fields. PMID:28386410

  16. {beta} - amyloid imaging probes

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Jae Min [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    2007-04-15

    Imaging distribution of {beta} - amyloid plaques in Alzheimer's disease is very important for early and accurate diagnosis. Early trial of the {beta} -amyloid plaques includes using radiolabeled peptides which can be only applied for peripheral {beta} - amyloid plaques due to limited penetration through the blood brain barrier (BBB). Congo red or Chrysamine G derivatives were labeled with Tc-99m for imaging {beta} - amyloid plaques of Alzheimer patient's brain without success due to problem with BBB penetration. Thioflavin T derivatives gave breakthrough for {beta} - amyloid imaging in vivo, and a benzothiazole derivative [C-11]6-OH-BTA-1 brought a great success. Many other benzothiazole, benzoxazole, benzofuran, imidazopyridine, and styrylbenzene derivatives have been labeled with F-18 and I-123 to improve the imaging quality. However, [C-11]6-OH-BTA-1 still remains as the best. However, short half-life of C-11 is a limitation of wide distribution of this agent. So, it is still required to develop an Tc-99m, F-18 or I-123 labeled agent for {beta} - amyloid imaging agent.

  17. Top-up operation experience at APS.

    Energy Technology Data Exchange (ETDEWEB)

    Emery, L.

    1999-03-31

    The Advanced Photon Source (APS) is a 7-OeV, third-generation synchrotrons radiation source. To provide more stable beam for users, in September 1998 we began commissioning a new operating mode called ''top-up.'' In this mode, the beam current does not decay but is maintained at a high level using frequent injection, while photon shutters are open and photon beams are delivered to users. The hardware, software, and safety requirements for top-up will be reported. Safety issues related to injection with open photon shutters are covered in companion papers in this conference. Recent operational experience includes testing aspects of top-up injection and delivering beam to X-ray users for a few hours with fractional current stability of 10{sup {minus}3}. We expect to run several top-up operation shifts in Spring 1999. Issues of importance are orbit and emittance transients during the injection and scheduling of injection pulses for the convenience of users.

  18. Beta cell dynamics: beta cell replenishment, beta cell compensation and diabetes.

    Science.gov (United States)

    Cerf, Marlon E

    2013-10-01

    Type 2 diabetes, characterized by persistent hyperglycemia, arises mostly from beta cell dysfunction and insulin resistance and remains a highly complex metabolic disease due to various stages in its pathogenesis. Glucose homeostasis is primarily regulated by insulin secretion from the beta cells in response to prevailing glycemia. Beta cell populations are dynamic as they respond to fluctuating insulin demand. Beta cell replenishment and death primarily regulate beta cell populations. Beta cells, pancreatic cells, and extra-pancreatic cells represent the three tiers for replenishing beta cells. In rodents, beta cell self-replenishment appears to be the dominant source for new beta cells supported by pancreatic cells (non-beta islet cells, acinar cells, and duct cells) and extra-pancreatic cells (liver, neural, and stem/progenitor cells). In humans, beta cell neogenesis from non-beta cells appears to be the dominant source of beta cell replenishment as limited beta cell self-replenishment occurs particularly in adulthood. Metabolic states of increased insulin demand trigger increased insulin synthesis and secretion from beta cells. Beta cells, therefore, adapt to support their physiology. Maintaining physiological beta cell populations is a strategy for targeting metabolic states of persistently increased insulin demand as in diabetes.

  19. Jets from Merging Neutron Stars

    Science.gov (United States)

    Kohler, Susanna

    2016-06-01

    With the recent discovery of gravitational waves from the merger of two black holes, its especially important to understand the electromagnetic signals resulting from mergers of compact objects. New simulations successfully follow a merger of two neutron stars that produces a short burst of energy via a jet consistent with short gamma-ray burst (sGRB) detections.Still from the authors simulation showing the two neutron stars, and their magnetic fields, before merger. [Adapted from Ruiz et al. 2016]Challenging SystemWe have long suspected that sGRBs are produced by the mergers of compact objects, but this model has been difficult to prove. One major hitch is that modeling the process of merger and sGRB launch is very difficult, due to the fact that these extreme systems involve magnetic fields, fluids and full general relativity.Traditionally, simulations are only able to track such mergers over short periods of time. But in a recent study, Milton Ruiz (University of Illinois at Urbana-Champaign and Industrial University of Santander, Colombia) and coauthors Ryan Lang, Vasileios Paschalidis and Stuart Shapiro have modeled a binary neutron star system all the way through the process of inspiral, merger, and the launch of a jet.A Merger TimelineHow does this happen? Lets walk through one of the teams simulations, in which dipole magnetic field lines thread through the interior of each neutron star and extend beyond its surface(like magnetic fields found in pulsars). In this example, the two neutron stars each have a mass of 1.625 solar masses.Simulation start (0 ms)Loss of energy via gravitational waves cause the neutron stars to inspiral.Merger (3.5 ms)The neutron stars are stretched by tidal effects and make contact. Their merger produces a hypermassive neutron star that is supported against collapse by its differential (nonuniform) rotation.Delayed collapse into a black hole (21.5 ms)Once the differential rotation is redistributed by magnetic fields and partially

  20. AP233: An Information Model for Systems Engineering

    Science.gov (United States)

    Siebes, Georg

    2009-01-01

    In today's world, information is abundant. We have no problems generating it. But we are challenged to find, organize, and exchange information. center dot A standardized model of information can help. Such a model nearly completed its development for Systems Engineering. It is referred to as AP233 (AP = Application Protocol).

  1. APS extends open access to all its journals

    CERN Multimedia

    Thomas, Kim

    2006-01-01

    "Physics research promoter and publisher the American Physical Society (APS) is to extend open access to all its journals. Th APS previously made its five print journals available through subscriptions, and its two e-journals (Physical Review Special Topics and Physics Educatoin Research) on an open access basis." (1/2 page)

  2. Surveying the Bright Stars by Optical Interferometry I: A Search for Multiplicity Among Stars of Spectral Types F - K

    CERN Document Server

    Hutter, Donald; Tycner, Christopher; Benson, James; Hummel, Christian; Sanborn, Jason; Franz, Otto G; Johnston, Kenneth

    2016-01-01

    We present the first results from an ongoing survey for multiplicity among the bright stars using the Navy Precision Optical Interferometer (NPOI). We first present a summary of NPOI observations of known multiple systems, including the first detection of the companion of $\\beta$ Scuti with precise relative astrometry, to illustrate the instrument's detection sensitivity for binaries at magnitude differences $\\Delta$$m$ $\\lessapprox$ 3 over the range of angular separation 3 - 860 milliarcseconds (mas). A limiting $\\Delta$$m_{700}$ $\\sim$ 3.5 is likely for binaries where the component spectral types differ by less than two. Model fits to these data show good agreement with published orbits, and we additionally present a new orbit solution for one of these stars, $\\sigma$ Her. We then discuss early results of the survey of bright stars at $\\delta$ $\\geq$ -20$\\deg$. This survey, which complements previous surveys of the bright stars by speckle interferometry, initially emphasizes bright stars of spectral types F...

  3. Differential Radial Velocities and Stellar Parameters of Nearby Young Stars

    CERN Document Server

    Yelda, D P S

    2006-01-01

    Radial velocity searches for substellar mass companions have focused primarily on stars older than 1 Gyr. Increased levels of stellar activity in young stars hinders the detection of solar system analogs and therefore there has been a prejudice against inclusion of young stars in radial velocity surveys until recently. Adaptive optics surveys of young stars have given us insight into the multiplicity of young stars but only for massive, distant companions. Understanding the limit of the radial velocity technique, restricted to high-mass, close-orbiting planets and brown dwarfs, we began a survey of young stars of various ages. While the number of stars needed to carry out full analysis of the problems of planetary and brown dwarf population and evolution is large, the beginning of such a sample is included here. We report on 61 young stars ranging in age from beta Pic association (~12 Myr) to the Ursa Majoris association (~300 Myr). This initial search resulted in no stars showing evidence for companions grea...

  4. Update On the Puzzling Boyajian's Star

    Science.gov (United States)

    Kohler, Susanna

    2016-09-01

    variations in stars near in the sky to Boyajians Star, and infrared observation of the star with JWST to search for heat signatures.CitationJason T. Wright and Steinn Sigurdsson 2016 ApJ 829 L3. doi:10.3847/2041-8205/829/1/L3

  5. V and K-band Mass-Luminosity Relations for M Dwarf Stars

    Science.gov (United States)

    Benedict, George Frederick; Henry, Todd J.; McArthur, Barbara E.; Franz, Otto; Wasserman, Larry H.; Dieterich, Sergio

    2015-08-01

    Applying Hubble Space Telescope Fine Guidance Sensor astrometric techniques developed to establish relative orbits for binary stars (Franz et al. 1998, AJ, 116, 1432), determine masses of binary components (Benedict et al. 2001, AJ, 121, 1607), and measure companion masses of exoplanet host stars (McArthur et al. 2010, ApJ, 715, 1203), we derive masses with an average 2% error for 28 components of 14 M dwarf binary star systems. With these and other published masses we update the lower Main Sequence V-band Mass-Luminosity Relation first shown in Henry et al. 1999, ApJ, 512, 864. We demonstrate that a Mass-Luminosity Relation in the K-band has far less scatter. These relations can be used to estimate the masses of the ubiquitous red dwarfs (75% of all stars) to an accuracy of better than 5%.

  6. Brightness Independent 4-Star Matching Algorithm for Lost-in-Space 3-Axis Attitude Acquisition

    Institute of Scientific and Technical Information of China (English)

    DONG Ying; XING Fei; YOU Zheng

    2006-01-01

    A star identification algorithm was developed for a charge-coupled device (CCD) or complementary metal-oxide-semiconductor (CMOS) autonomous star tracker to acquire 3-axis attitude information for a lost-in-space spacecraft. The algorithm took advantage of an efficient on-board database and an original "4-star matching" pattern recognition strategy to achieve fast and reliable star identification. The on-board database was composed of a brightness independent guide star catalog (mission catalog) and a K-vector star pair catalog. The star pattern recognition method involved direct location of star pair candidates and a simple array matching procedure. Tests of the algorithm with a CMOS active pixel sensor (APS) star tracker result in a 99.9% success rate for star identification for lost-in-space 3-axis attitude acquisition when the angular measurement accuracy of the star tracker is at least 0.01°. The brightness independent algorithm requires relatively higher measurement accuracy of the star apparent positions that can be easily achieved by CCD or CMOS sensors along with subpixel centroiding techniques.

  7. Infrared spectroscopy of star formation in galaxies

    Science.gov (United States)

    Beck, Sara C.; Ho, Paul T. P.; Turner, Jean L.

    1987-01-01

    The Brackett alpha and beta lines with 7.2 seconds angular and 350 km/s velocity resolution were observed in 11 infrared-bright galaxies. From these measurements extinctions, Lyman continuum fluxes, and luminosities due to OB stars were derived. The galaxies observed to date are NGC3690, M38, NGC 5195, Arp 220, NGC 520, NGC660, NGC1614, NGC 3079, NGC 6946, NGC 7714, and Maffei 2, all of which were suggested at some time to be starburst ogjects. The contributions of OB stars to the luminosities of these galaxies can be quantified from the measurements and range from insignificant to sufficient to account for the total energy output. The OB stellar luminosities observed are as high as 10 to the 12th solar luminosities in the galaxy NGC 1614. It is noteworthy that star formation can play very different roles in the infrared energy output of galaxies of similar luminosity, as for example Arp 220 and NGC 1614. In addition to probing the star formation process in these galaxies, the Brackett line measurements, when compared to radio and infrared continuum results, have revealed some unexpected and at present imperfectly understood phenomena: in some very luminous sources the radio continuum appears to be suppressed relative to the infrared recombination lines; in many galaxies there is a substantial excess of 10 micron flux over that predicted from simple models of Lyman alpha heating of dust if young stars are the only significant energy source.

  8. Spectroscopic variability of two Oe stars

    CERN Document Server

    Rauw, G; Naze, Y; Eversberg, T; Alves, F; Arnold, W; Bergmann, T; Viegas, N G Correia; Fahed, R; Fernando, A; Gonzalez-Perez, J N; Carreira, L F Gouveia; Hempelmann, A; Hunger, T; Knapen, J H; Leadbeater, R; Dias, F Marques; Mittag, M; Moffat, A F J; Reinecke, N; Ribeiro, J; Romeo, N; Gallego, J Sanchez; Santos, E M Dos; Schanne, L; Schmitt, J H M M; Schroeder, K -P; Stahl, O; Stober, Ba; Stober, Be; Vollmann, K

    2015-01-01

    The Oe stars HD45314 and HD60848 have recently been found to exhibit very different X-ray properties: whilst HD60848 has an X-ray spectrum and emission level typical of most OB stars, HD45314 features a much harder and brighter X-ray emission, making it a so-called gamma Cas analogue. Monitoring the optical spectra could provide hints towards the origin of these very different behaviours. We analyse a large set of spectroscopic observations of HD45314 and HD60848, extending over 20 years. We further attempt to fit the H-alpha line profiles of both stars with a simple model of emission line formation in a Keplerian disk. Strong variations in the strengths of the H-alpha, H-beta, and He I 5876 emission lines are observed for both stars. In the case of HD60848, we find a time lag between the variations in the equivalent widths of these lines. The emission lines are double peaked with nearly identical strengths of the violet and red peaks. The H-alpha profile of this star can be successfully reproduced by our mod...

  9. Braking the Gas in the beta Pictoris Disk

    CERN Document Server

    Fern'andez, R; Wu, Y; Brandeker, Alexis; Fern\\'andez, Rodrigo

    2006-01-01

    (Abridged) The main sequence star beta Pictoris hosts the best studied circumstellar disk to date. Nonetheless, a long-standing puzzle has been around since the detection of metallic gas in the disk: radiation pressure from the star should blow the gas away, yet the observed motion is consistent with Keplerian rotation. In this work we search for braking mechanisms that can resolve this discrepancy. We find that all species affected by radiation force are heavily ionized and dynamically coupled into a single fluid by Coulomb collisions, reducing the radiation force on species feeling the strongest acceleration. For a gas of solar composition, the resulting total radiation force still exceeds gravity, while a gas of enhanced carbon abundance could be self-braking. We also explore two other braking agents: collisions with dust grains and neutral gas. Grains surrounding beta Pic are photoelectrically charged to a positive electrostatic potential. If a significant fraction of the grains are carbonaceous (10% in t...

  10. Boosted beta regression.

    Directory of Open Access Journals (Sweden)

    Matthias Schmid

    Full Text Available Regression analysis with a bounded outcome is a common problem in applied statistics. Typical examples include regression models for percentage outcomes and the analysis of ratings that are measured on a bounded scale. In this paper, we consider beta regression, which is a generalization of logit models to situations where the response is continuous on the interval (0,1. Consequently, beta regression is a convenient tool for analyzing percentage responses. The classical approach to fit a beta regression model is to use maximum likelihood estimation with subsequent AIC-based variable selection. As an alternative to this established - yet unstable - approach, we propose a new estimation technique called boosted beta regression. With boosted beta regression estimation and variable selection can be carried out simultaneously in a highly efficient way. Additionally, both the mean and the variance of a percentage response can be modeled using flexible nonlinear covariate effects. As a consequence, the new method accounts for common problems such as overdispersion and non-binomial variance structures.

  11. ENERGY STAR Certified Furnaces

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 4.0 ENERGY STAR Program Requirements for Furnaces that are effective as of February 1,...

  12. ENERGY STAR Certified Boilers

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 3.0 ENERGY STAR Program Requirements for Boilers that are effective as of October 1,...

  13. ENERGY STAR Certified Computers

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 6.1 ENERGY STAR Program Requirements for Computers that are effective as of June 2, 2014....

  14. Aperture-free star formation rate of SDSS star-forming galaxies

    CERN Document Server

    Puertas, S Duarte; Iglesias-Paramo, J; Kehrig, C; Perez-Montero, E; Rosales-Ortega, F F

    2016-01-01

    Large area surveys with a high number of galaxies observed have undoubtedly marked a milestone in the understanding of several properties of galaxies, such as star-formation history, morphology, and metallicity. However, in many cases, these surveys provide fluxes from fixed small apertures (e.g. fibre), which cover a scant fraction of the galaxy, compelling us to use aperture corrections to study the global properties of galaxies. In this work, we derive the current total star formation rate (SFR) of Sloan Digital Sky Survey (SDSS) star-forming galaxies, using an empirically based aperture correction of the measured $\\rm H\\alpha$ flux for the first time, thus minimising the uncertainties associated with reduced apertures. All the $\\rm H\\alpha$ fluxes have been extinction-corrected using the $\\rm H\\alpha/H\\beta$ ratio free from aperture effects. The total SFR for $\\sim$210,000 SDSS star-forming galaxies has been derived applying pure empirical $\\rm H\\alpha$ and $\\rm H\\alpha/H\\beta$ aperture corrections based ...

  15. Autonomous Star Tracker Algorithms

    DEFF Research Database (Denmark)

    Betto, Maurizio; Jørgensen, John Leif; Kilsgaard, Søren

    1998-01-01

    Proposal, in response to an ESA R.f.P., to design algorithms for autonomous star tracker operations.The proposal also included the development of a star tracker breadboard to test the algorithms performances.......Proposal, in response to an ESA R.f.P., to design algorithms for autonomous star tracker operations.The proposal also included the development of a star tracker breadboard to test the algorithms performances....

  16. Star operations and Pullbacks

    OpenAIRE

    Fontana, Marco; Park, Mi Hee

    2003-01-01

    In this paper we study the star operations on a pullback of integral domains. In particular, we characterize the star operations of a domain arising from a pullback of ``a general type'' by introducing new techniques for ``projecting'' and ``lifting'' star operations under surjective homomorphisms of integral domains. We study the transfer in a pullback (or with respect to a surjective homomorphism) of some relevant classes or distinguished properties of star operations such as $v-, t-, w-, b...

  17. A probable giant planet imaged in the Beta Pictoris disk

    CERN Document Server

    Lagrange, A -M; Chauvin, G; Fusco, T; Ehrenreich, D; Mouillet, D; Rousset, G; Rouan, D; Allard, F; Gendron, E; Charton, J; Mugnier, L; Rabou, P; Montri, J; Lacombe, F

    2008-01-01

    Since the discovery of its dusty disk in 1984, Beta Pictoris has become the prototype of young early-type planetary systems, and there are now various indications that a massive Jovian planet is orbiting the star at ~ 10 AU. However, no planets have been detected around this star so far. Our goal was to investigate the close environment of Beta Pic, searching for planetary companion(s). Deep adaptive-optics L'-band images of Beta Pic were recorded using the NaCo instrument at the Very Large Telescope. A faint point-like signal is detected at a projected distance of ~ 8 AU from the star, within the North-East side of the dust disk. Various tests were made to rule out with a good confidence level possible instrumental or atmospheric artifacts. The probability of a foreground or background contaminant is extremely low, based in addition on the analysis of previous deep Hubble Space Telescope images. The object L'=11.2 apparent magnitude would indicate a typical temperature of ~1500 K and a mass of ~ 8 Jovian mas...

  18. Standard Stars for the BYU H-alpha Photometric System (Abstract)

    Science.gov (United States)

    Joner, M.; Hintz, E.

    2015-12-01

    (Abstract only) We present primary standard stars for the BYU H-alpha photometric system. This system is similar to the H-beta photometric system that is often used with the intermediate band uvby system. Both systems use the difference between magnitudes measured in a wide (15-20-nm) and narrow (3-nm) bandpass centered on one of the strong Balmer lines of hydrogen to establish a color index. Line indices formed in this manner are independent of atmospheric extinction and interstellar reddening. These indices provide intrinsic measures of effective temperature for stars with spectral types between B and G. The present primary standard stars for the BYU system as established using spectroscopic observations that cover the region between the H-alpha and H-beta lines. The indices were formed using synthetic photometry reductions to convolve ideal filter profiles with the observed spectra. The number of observations per star is generally in excess of 25. Some stars have been observed more than 100 times over a period of 7 years. The typical error per observation for these stars is on the order of 1-3 mmag. In addition to the standard field stars, we present H-alpha and H-beta observations of individual stars that are members of selected open clusters. These include the Hyades, Pleiades, Coma, and NGC 752 clusters. Additional stars that exhibit varying degrees of hydrogen emission are easily distinguished in a plot of the alpha-beta plane. We have found that candidates for emission line objects, high mass x-ray binaries, and young stellar objects are readily identified in our alpha-beta plots. We acknowledge continued support from the BYU College of Physical and Mathematical Sciences as well as support from NSF Grant AST #0618209. We also thank the Dominion Astrophysical Observatory for continued allocation of robotic observing time for spectroscopy on the 1.2-m telescope.

  19. Beta and Gamma Gradients

    DEFF Research Database (Denmark)

    Løvborg, Leif; Gaffney, C. F.; Clark, P. A.;

    1985-01-01

    Experimental and/or theoretical estimates are presented concerning, (i) attenuation within the sample of beta and gamma radiation from the soil, (ii) the gamma dose within the sample due to its own radioactivity, and (iii) the soil gamma dose in the proximity of boundaries between regions...... of differing radioactivity. It is confirmed that removal of the outer 2 mm of sample is adequate to remove influence from soil beta dose and estimates are made of the error introduced by non-removal. Other evaluations include variation of the soil gamma dose near the ground surface and it appears...

  20. First Zeeman Doppler imaging of a cool star using all four Stokes parameters

    CERN Document Server

    Rosén, Lisa; Wade, Gregg A

    2015-01-01

    Magnetic fields are ubiquitous in active cool stars but they are in general complex and weak. Current Zeeman Doppler imaging (ZDI) studies of cool star magnetic fields chiefly employ circular polarization observations because linear polarization is difficult to detect and requires a more sophisticated radiative transfer modeling to interpret. But it has been shown in previous theoretical studies, and in the observational analyses of magnetic Ap stars, that including linear polarization in the magnetic inversion process makes it possible to correctly recover many otherwise lost or misinterpreted magnetic features. We have obtained phase-resolved observations in all four Stokes parameters of the RS CVn star II Peg at two separate epochs. Here we present temperature and magnetic field maps reconstructed for this star using all four Stokes parameters. This is the very first such ZDI study of a cool active star. Our magnetic inversions reveal a highly structured magnetic field topology for both epochs. The strengt...

  1. Covering tree with stars

    DEFF Research Database (Denmark)

    Baumbach, Jan; Guo, Jian-Ying; Ibragimov, Rashid

    2013-01-01

    We study the tree edit distance problem with edge deletions and edge insertions as edit operations. We reformulate a special case of this problem as Covering Tree with Stars (CTS): given a tree T and a set of stars, can we connect the stars in by adding edges between them such that the resulting ...

  2. Covering tree with stars

    DEFF Research Database (Denmark)

    Baumbach, Jan; Guo, Jiong; Ibragimov, Rashid

    2015-01-01

    We study the tree edit distance problem with edge deletions and edge insertions as edit operations. We reformulate a special case of this problem as Covering Tree with Stars (CTS): given a tree T and a set of stars, can we connect the stars in by adding edges between them such that the resulting ...

  3. Magnetism in massive stars

    NARCIS (Netherlands)

    Henrichs, H.F.

    2012-01-01

    Stars with mass more than 8 solar masses end their lives as neutron stars, which we mostly observe as highly magnetized objects. Where does this magnetic field come from? Such a field could be formed during the collapse, or is a (modified) remnant of a fossil field since the birth of the star, or ot

  4. Managing the star performer.

    Science.gov (United States)

    Hills, Laura

    2013-01-01

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

  5. America's Star Libraries

    Science.gov (United States)

    Lyons, Ray; Lance, Keith Curry

    2009-01-01

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

  6. To rescue a star

    OpenAIRE

    1996-01-01

    Massless neutrinos are exchanged in a neutron star, leading to long range interactions. Many body forces of this type follow and we resum them. Their net contribution to the total energy is negligible as compared to the star mass. The stability of the star is not in danger, contrary to recent assertions.

  7. Analysis of Kepler B stars: rotational modulation and Maia variables

    CERN Document Server

    Balona, L A; Daszynska-Daszkiewicz, J; De Cat, P

    2015-01-01

    We examine 4-yr almost continuous Kepler photometry of 115 B stars. We find that the light curves of 39 percent of these stars are simply described by a low-frequency sinusoid and its harmonic, usually with variable amplitudes, which we interpret as rotational modulation. A large fraction (28 percent) of B stars might be classified as ellipsoidal variables, but a statistical argument suggests that these are probably rotational variables as well. About 8 percent of the rotational variables have a peculiar periodogram feature which is common among A stars. The physical cause of this is very likely related to rotation. The presence of so many rotating variables indicates the presence of star spots. This suggests that magnetic fields are indeed generated in radiative stellar envelopes. We find five beta Cep variables, all of which have low frequencies with relatively large amplitudes. The presence of these frequencies is a puzzle. About half the stars with high frequencies are cooler than the red edge of the beta...

  8. AP600 design certification thermal hydraulics testing and analysis

    Energy Technology Data Exchange (ETDEWEB)

    Hochreiter, L.E.; Piplica, E.J.

    1995-09-01

    Westinghouse Electric Corporation, in conjunction with the Department of Energy and the Electric Power Research Institute, have been developing an advanced light water reactor design; the AP600. The AP600 is a 1940 Mwt, 600Mwe unit which is similar to a Westinghouse two-loop Pressurized Water Reactor. The accumulated knowledge on reactor design to reduce the capital costs, construction time, and the operational and maintenance cost of the unit once it begins to generate electrical power. The AP600 design goal is to maintain an overall cost advantage over fossil generated electrical power.

  9. A new gap separation mechanism for APS insertion devices.

    Energy Technology Data Exchange (ETDEWEB)

    Trakhtenberg, E. M.; Tcheskidov, V.; Den Hartog, P. K.; Deriy, B.; Erdmann, M.; Makarov, O.; Moog, E. R.

    1999-10-25

    A new gap separation mechanism for use with the standard Advanced Photon Source (APS) 3.3-cm-period undulator magnetic structures has been designed and built and the first system has been installed in the APS storage ring. The system allows a minimum magnetic gap of 10 mm for use with the APS 8-mm insertion device vacuum chambers. The mechanism is a bolted steel frame structure with a simple 4-motor mechanical drive train. The control system uses servomotors with incremental rotary encoders and virtual absolute linear encoders.

  10. Further stable neutron star models from f(R) gravity

    Energy Technology Data Exchange (ETDEWEB)

    Astashenok, Artyom V. [I. Kant Baltic Federal University, Institute of Physics and Technology, Nevskogo st. 14, Kaliningrad, 236041 (Russian Federation); Capozziello, Salvatore [Dipartimento di Fisica, Università di Napoli ' ' Federico II' ' , Via Cinthia, 9, Napoli, I–80126 (Italy); Odintsov, Sergei D., E-mail: artyom.art@gmail.com, E-mail: capozziello@na.infn.it, E-mail: odintsov@ieec.uab.es [Instituciò Catalana de Recerca i Estudis Avançats (ICREA), Barcelona (Spain)

    2013-12-01

    Neutron star models in perturbative f(R) gravity are considered with realistic equations of state. In particular, we consider the FPS, SLy and other equations of state and a case of piecewise equation of state for stars with quark cores. The mass-radius relations for f(R) = R+R(e{sup −R/R{sub 0}}−1) model and for R{sup 2} models with logarithmic and cubic corrections are obtained. In the case of R{sup 2} gravity with cubic corrections, we obtain that at high central densities (ρ > 10ρ{sub ns}, where ρ{sub ns} = 2.7 × 10{sup 14} g/cm{sup 3} is the nuclear saturation density), stable star configurations exist. The minimal radius of such stars is close to 9 km with maximal mass ∼ 1.9M{sub ⊙} (SLy equation). A similar situation takes place for AP4 and BSK20 EoS. Such an effect can give rise to more compact stars than in General Relativity. If observationally identified, such objects could constitute a formidable signature for modified gravity at astrophysical level. Another interesting result can be achieved in modified gravity with only a cubic correction. For some EoS, the upper limit of neutron star mass increases and therefore these EoS can describe realistic star configurations (although, in General Relativity, these EoS are excluded by observational constraints)

  11. Production of Proteasome Inhibitor Syringolin A by the Endophyte Rhizobium sp. Strain AP16

    Science.gov (United States)

    Bigler, Laurent; Dudler, Robert

    2014-01-01

    Syringolin A, the product of a mixed nonribosomal peptide synthetase/polyketide synthase encoded by the syl gene cluster, is a virulence factor secreted by certain Pseudomonas syringae strains. Together with the glidobactins produced by a number of beta- and gammaproteobacterial human and animal pathogens, it belongs to the syrbactins, a structurally novel class of proteasome inhibitors. In plants, proteasome inhibition by syringolin A-producing P. syringae strains leads to the suppression of host defense pathways requiring proteasome activity, such as the ones mediated by salicylic acid and jasmonic acid. Here we report the discovery of a syl-like gene cluster with some unusual features in the alphaproteobacterial endophyte Rhizobium sp. strain AP16 that encodes a putative syringolin A-like synthetase whose components share 55% to 65% sequence identity (72% to 79% similarity) at the amino acid level. As revealed by average nucleotide identity (ANI) calculations, this strain likely belongs to the same species as biocontrol strain R. rhizogenes K84 (formely known as Agrobacterium radiobacter K84), which, however, carries a nonfunctional deletion remnant of the syl-like gene cluster. Here we present a functional analysis of the syl-like gene cluster of Rhizobium sp. strain AP16 and demonstrate that this endophyte synthesizes syringolin A and some related minor variants, suggesting that proteasome inhibition by syrbactin production can be important not only for pathogens but also for endophytic bacteria in the interaction with their hosts. PMID:24727275

  12. Production of proteasome inhibitor syringolin A by the endophyte Rhizobium sp. strain AP16.

    Science.gov (United States)

    Dudnik, Alexey; Bigler, Laurent; Dudler, Robert

    2014-06-01

    Syringolin A, the product of a mixed nonribosomal peptide synthetase/polyketide synthase encoded by the syl gene cluster, is a virulence factor secreted by certain Pseudomonas syringae strains. Together with the glidobactins produced by a number of beta- and gammaproteobacterial human and animal pathogens, it belongs to the syrbactins, a structurally novel class of proteasome inhibitors. In plants, proteasome inhibition by syringolin A-producing P. syringae strains leads to the suppression of host defense pathways requiring proteasome activity, such as the ones mediated by salicylic acid and jasmonic acid. Here we report the discovery of a syl-like gene cluster with some unusual features in the alphaproteobacterial endophyte Rhizobium sp. strain AP16 that encodes a putative syringolin A-like synthetase whose components share 55% to 65% sequence identity (72% to 79% similarity) at the amino acid level. As revealed by average nucleotide identity (ANI) calculations, this strain likely belongs to the same species as biocontrol strain R. rhizogenes K84 (formely known as Agrobacterium radiobacter K84), which, however, carries a nonfunctional deletion remnant of the syl-like gene cluster. Here we present a functional analysis of the syl-like gene cluster of Rhizobium sp. strain AP16 and demonstrate that this endophyte synthesizes syringolin A and some related minor variants, suggesting that proteasome inhibition by syrbactin production can be important not only for pathogens but also for endophytic bacteria in the interaction with their hosts.

  13. Genetic and biochemical characterization of human AP endonuclease 1 mutants deficient in nucleotide incision repair activity.

    Directory of Open Access Journals (Sweden)

    Aurore Gelin

    Full Text Available BACKGROUND: Human apurinic/apyrimidinic endonuclease 1 (APE1 is a key DNA repair enzyme involved in both base excision repair (BER and nucleotide incision repair (NIR pathways. In the BER pathway, APE1 cleaves DNA at AP sites and 3'-blocking moieties generated by DNA glycosylases. In the NIR pathway, APE1 incises DNA 5' to a number of oxidatively damaged bases. At present, physiological relevance of the NIR pathway is fairly well established in E. coli, but has yet to be elucidated in human cells. METHODOLOGY/PRINCIPAL FINDING: We identified amino acid residues in the APE1 protein that affect its function in either the BER or NIR pathway. Biochemical characterization of APE1 carrying single K98A, R185A, D308A and double K98A/R185A amino acid substitutions revealed that all mutants exhibited greatly reduced NIR and 3'-->5' exonuclease activities, but were capable of performing BER functions to some extent. Expression of the APE1 mutants deficient in the NIR and exonuclease activities reduced the sensitivity of AP endonuclease-deficient E. coli xth nfo strain to an alkylating agent, methylmethanesulfonate, suggesting that our APE1 mutants are able to repair AP sites. Finally, the human NIR pathway was fully reconstituted in vitro using the purified APE1, human flap endonuclease 1, DNA polymerase beta and DNA ligase I proteins, thus establishing the minimal set of proteins required for a functional NIR pathway in human cells. CONCLUSION/SIGNIFICANCE: Taken together, these data further substantiate the role of NIR as a distinct and separable function of APE1 that is essential for processing of potentially lethal oxidative DNA lesions.

  14. The evolution of low mass, close binary systems with a neutron star component: a detailed grid

    CERN Document Server

    De Vito, M A

    2012-01-01

    In close binary systems composed of a normal, donor star and an accreting neutron star, the amount of material received by the accreting component is, so far, a real intrigue. In the literature there are available models that link the accretion disk surrounding the neutron star with the amount of material it receives, but there is no model linking the amount of matter lost by the donor star to that falling onto the neutron star. In this paper we explore the evolutionary response of these close binary systems when we vary the amount of material accreted by the neutron star. We consider a parameter \\beta, which represents the fraction of material lost by the normal star that can be accreted by the neutron star. \\beta is considered as constant throughout evolution. We have computed the evolution of a set of models considering initial donor star masses (in solar units) between 0.5 and 3.50, initial orbital periods (in days) between 0.175 and 12, initial masses of neutron stars (in solar units) of 0.80, 1.00, 1.20...

  15. A second glance at SN 2002ap and the M74 field with XMM-Newton

    CERN Document Server

    Soria, R; Mazzali, P A; Soria, Roberto; Pian, Elena

    2003-01-01

    We have re-observed the field of M74 in January 2003 with XMM-Newton, 11 months after the X-ray detection of SN 2002ap. From a comparison of the two XMM-Newton observations we obtain more accurate values for the X-ray luminosity and colours of the source five days after the event, and a limit on its decline rate. We compare its X-ray behaviour (prompt soft X-ray emission, relatively low luminosity) with that of other Type Ic SNe, and speculate that SN 2002ap may share some physical properties (low mass-loss rate and high-velocity stellar wind from the progenitor star) with the candidate hypernova/GRB progenitor SN 1998bw, but with a lower (non-relativistic) speed of the ejecta. We suggest that the X-ray emission observed in 2002 is likely to come from the radiatively-cooling reverse shock, at a temperature kT ~ 0.8 keV, and that this soft component was already detected 5 d after the event because the absorbing column density of the cool shell between the forward and reverse shocks was only ~ 10^{20} cm^{-2}, ...

  16. Effect of multifunctional protein YB-1 on the AP site cleavage by AP endonuclease 1 and tyrosyl phosphodiesterase 1

    Directory of Open Access Journals (Sweden)

    Ovchinnikov L. P.

    2012-07-01

    Full Text Available Apurinic/apyrimidinic sites (AP sites which represent one of the most abundantly generated DNA lesions in the cell are generally repaired by base excision repair (BER pathway. Multifunctional protein YB-1 is known to participate in cellular response to genotoxic stress and was shown to interact with several components of BER – DNA glycosylases NTH1, NEIL2, DNA polymerase and DNA ligase III. Therefore, it is of great interest to investigate the influence of YB-1 on one of the major BER enzymes, responsible for AP site cleavage, AP endonuclease APE1, and on tyrosyl phosphodiesterase Tdp1, participating in APE1 independent pathway of AP site repair. Aim. Effect of multifunctional protein YB-1 on the AP site cleavage by the activities of APE1 and Tdp1 was studied. Methods. Gel-mobility shift assays and enzyme activity tests. Results. YB-1 was shown to inhibit the cleavage of AP site located in single-stranded DNA by both APE1 and Tdp1. Stimulation of APE1 activity on protruding double-stranded DNA in the presence of YB-1 was observed, whereas no effect on Tdp1-mediated cleavage of AP site in double-stranded DNA was found. Conclusions. YB-1 can modulate the repair of AP sites in DNA by both positively stimulating APE1 during the classic BER of AP sites and avoiding a possible generation of doublestrand breaks, arising from the cleavage of single-stranded portion of DNA substrate already used by different DNA-processing pathway

  17. Nuclear physics of stars

    CERN Document Server

    Iliadis, Christian

    2015-01-01

    Most elements are synthesized, or ""cooked"", by thermonuclear reactions in stars. The newly formed elements are released into the interstellar medium during a star's lifetime, and are subsequently incorporated into a new generation of stars, into the planets that form around the stars, and into the life forms that originate on the planets. Moreover, the energy we depend on for life originates from nuclear reactions that occur at the center of the Sun. Synthesis of the elements and nuclear energy production in stars are the topics of nuclear astrophysics, which is the subject of this book

  18. Magnetic chemically peculiar stars

    CERN Document Server

    Schöller, Markus

    2015-01-01

    Chemically peculiar (CP) stars are main-sequence A and B stars with abnormally strong or weak lines for certain elements. They generally have magnetic fields and all observables tend to vary with the same period. Chemically peculiar stars provide a wealth of information; they are natural atomic and magnetic laboratories. After a brief historical overview, we discuss the general properties of the magnetic fields in CP stars, describe the oblique rotator model, explain the dependence of the magnetic field strength on the rotation, and concentrate at the end on HgMn stars.

  19. Applied Beta Dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Rich, B.L.

    1986-01-01

    Measurements of beta and/or nonpenetrating exposure results is complicated and past techniques and capabilities have resulted in significant inaccuracies in recorded results. Current developments have resulted in increased capabilities which make the results more accurate and should result in less total exposure to the work force. Continued development of works in progress should provide equivalent future improvements.

  20. Beta Thalassemia (For Parents)

    Science.gov (United States)

    ... had their spleens removed. Slower growth rates. The anemia resulting from beta thalassemia can cause children to grow more slowly and also can lead ... boost production of new red blood cells. Some children with moderate anemia may require an occasional blood transfusion , particularly after ...

  1. Trichoderma .beta.-glucosidase

    Science.gov (United States)

    Dunn-Coleman, Nigel; Goedegebuur, Frits; Ward, Michael; Yao, Jian

    2006-01-03

    The present invention provides a novel .beta.-glucosidase nucleic acid sequence, designated bgl3, and the corresponding BGL3 amino acid sequence. The invention also provides expression vectors and host cells comprising a nucleic acid sequence encoding BGL3, recombinant BGL3 proteins and methods for producing the same.

  2. Roughing up Beta

    DEFF Research Database (Denmark)

    Bollerslev, Tim; Li, Sophia Zhengzi; Todorov, Viktor

    Motivated by the implications from a stylized equilibrium pricing framework, we investigate empirically how individual equity prices respond to continuous, or \\smooth," and jumpy, or \\rough," market price moves, and how these different market price risks, or betas, are priced in the cross-section...

  3. Tank characterization report for double shell tank 241-AP-104

    Energy Technology Data Exchange (ETDEWEB)

    Winkelman, W.D., Westinghouse Hanford

    1996-08-07

    This document summarizes the information on the historical uses, present status, and the sampling and analysis results of waste stored in Tank 241-AP-104. This report supports the requirements of Tri-Party Agreement Milestone M-44-09.

  4. A hot-spare injector for the APS linac.

    Energy Technology Data Exchange (ETDEWEB)

    Lewellen, J. W.

    1999-04-13

    Last year a second-generation SSRL-type thermionic cathode rf gun was installed in the Advanced Photon Source (APS) linac. This gun (referred to as ''gun2'') has been successfully commissioned and now serves as the main injector for the APS linac, essentially replacing the Koontz-type DC gun. To help ensure injector availability, particularly with the advent of top-up mode operation at the APS, a second thermionic-cathode rf gun will be installed in the APS linac to act as a hot-spare beam source. The hot-spare installation includes several unique design features, including a deep-orbit Panofsky-style alpha magnet. Details of the hot-spare beamline design and projected performance are presented, along with some plans for future performance upgrades.

  5. Lumbar pedicle screw placement: Using only AP plane imaging

    Directory of Open Access Journals (Sweden)

    Anil Sethi

    2012-01-01

    Conclusion: Placement of pedicle screws under fluoroscopic guidance using AP plane imaging alone with tactile guidance is safe, fast, and reliable. However, a good understanding of the radiographic landmarks is a prerequisite.

  6. Roles of AP-2 in clathrin-mediated endocytosis.

    Directory of Open Access Journals (Sweden)

    Emmanuel Boucrot

    Full Text Available BACKGROUND: The notion that AP-2 clathrin adaptor is an essential component of an endocytic clathrin coat appears to conflict with recent observations that substantial AP-2 depletion, using RNA interference with synthesis of AP-2 subunits, fails to block uptake of certain ligands known to internalize through a clathrin-based pathway. METHODOLOGY/PRINCIPAL FINDINGS: We report here the use of in vivo imaging data obtained by spinning-disk confocal microscopy to study the formation of clathrin-coated structures at the plasma membranes of BSC1 and HeLa cells depleted by RNAi of the clathrin adaptor, AP-2. Very few clathrin coats continue to assemble after AP-2 knockdown. Moreover, there is a total absence of clathrin-containing structures completely lacking AP-2 while all the remaining coats still contain a small amount of AP-2. These observations suggest that AP-2 is essential for endocytic coated-pit and coated-vesicle formation. We also find that AP-2 knockdown strongly inhibits light-density lipoprotein (LDL receptor-mediated endocytosis, as long as cells are maintained in complete serum and at 37 degrees C. If cells are first incubated with LDL at 4 degrees C, followed by warming, there is little or no decrease in LDL uptake with respect to control cells. LDL uptake at 37 degrees C is also not affected in AP-2 depleted cells first deprived of LDL by incubation with either serum-starved or LDL-starved cells for 24 hr. The LDL-deprived cells display a significant increase in endocytic structures enriched on deeply invaginated tubes that contain LDL and we suggest that under this condition of stress, LDL might enter through this alternative pathway. CONCLUSIONS/SIGNIFICANCE: These results suggest that AP-2 is essential for endocytic clathrin coated-pit and coated-vesicle formation. They also indicate that under normal conditions, functional endocytic clathrin coated pits are required for LDL internalization. We also show that under certain

  7. Utilizing Synthetic UV Spectra to Explore the Physical Basis for the Classification of Lambda Boötis Stars

    Science.gov (United States)

    Cheng, Kwang-Ping; Neff, James E.; Johnson, Dustin M.; Tarbell, Erik S.; Romo, Christopher A.; Prabhaker, Arvind; Steele, Patricia A.; Gray, Richard O.; Corbally, Christopher J.

    2016-04-01

    Lambda Boo-type stars are a group of late B to early F-type Population I dwarfs that show mild to extreme deficiencies of iron-peak elements (up to 2 dex), but their C, N, O, and S abundances are near solar. This intriguing stellar class has recently regained the spotlight because of the directly imaged planets around a confirmed Lambda Boo star, HR 8799, and a suggested Lambda Boo star, Beta Pictoris. The discovery of a giant asteroid belt around Vega, another possible Lambda Boo star, also suggests hidden planets. The possible link between Lambda Boo stars and planet-bearing stars motivates us to study Lambda Boo stars systematically. Since the peculiar nature of the prototype Lambda Boötis was first noticed in 1943, Lambda Boo candidates published in the literature have been selected using widely different criteria. In order to determine the origin of Lambda Boo stars’ unique abundance pattern and to better discriminate between theories explaining the Lambda Boo phenomenon, a consistent working definition of Lambda Boo stars is needed. We have re-evaluated all published Lambda Boo candidates and their available ultraviolet and visible spectra. In this paper, using observed and synthetic spectra, we explore the physical basis for the classification of Lambda Boo stars, and develop quantitative criteria that discriminate metal-poor stars from bona fide Lambda Boo stars. Based on these stricter Lambda Boo classification criteria, we conclude that neither Beta Pictoris nor Vega should be classified as Lambda Boo stars.

  8. UTILIZING SYNTHETIC UV SPECTRA TO EXPLORE THE PHYSICAL BASIS FOR THE CLASSIFICATION OF LAMBDA BOÖTIS STARS

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Kwang-Ping; Johnson, Dustin M.; Tarbell, Erik S.; Romo, Christopher A.; Prabhaker, Arvind [Cal. State Univ., Fullerton, Fullerton, CA (United States); Neff, James E.; Steele, Patricia A. [College of Charleston, Charleston, SC (United States); Gray, Richard O. [Appalachian State Univ., Boone, NC (United States); Corbally, Christopher J. [Vatican Observatory, Tucson, AZ (United States)

    2016-04-15

    Lambda Boo-type stars are a group of late B to early F-type Population I dwarfs that show mild to extreme deficiencies of iron-peak elements (up to 2 dex), but their C, N, O, and S abundances are near solar. This intriguing stellar class has recently regained the spotlight because of the directly imaged planets around a confirmed Lambda Boo star, HR 8799, and a suggested Lambda Boo star, Beta Pictoris. The discovery of a giant asteroid belt around Vega, another possible Lambda Boo star, also suggests hidden planets. The possible link between Lambda Boo stars and planet-bearing stars motivates us to study Lambda Boo stars systematically. Since the peculiar nature of the prototype Lambda Boötis was first noticed in 1943, Lambda Boo candidates published in the literature have been selected using widely different criteria. In order to determine the origin of Lambda Boo stars’ unique abundance pattern and to better discriminate between theories explaining the Lambda Boo phenomenon, a consistent working definition of Lambda Boo stars is needed. We have re-evaluated all published Lambda Boo candidates and their available ultraviolet and visible spectra. In this paper, using observed and synthetic spectra, we explore the physical basis for the classification of Lambda Boo stars, and develop quantitative criteria that discriminate metal-poor stars from bona fide Lambda Boo stars. Based on these stricter Lambda Boo classification criteria, we conclude that neither Beta Pictoris nor Vega should be classified as Lambda Boo stars.

  9. Army and Marine Corps Active Protection System (APS) Efforts

    Science.gov (United States)

    2016-08-30

    Expedited NDI effort. The Marines have a number of unique APS requirements—including the ability to be transported by ship and withstand salt water...in urban environments. Such constraints could limit the usefulness of APS in certain combat scenarios. Collateral Damage In a manner similar to...fired at short range, in open area or urban environment, AT Guided Missiles, High Explosive AT and Kinetic Energy rounds. The Iron Fist is

  10. Army and Marine Corps Active Protection System (APS) Efforts

    Science.gov (United States)

    2016-08-30

    Summary Active Protection Systems (APSs) are subsystems integrated into or installed on a combat vehicle to automatically acquire, track, and respond...Protection System (APS) Efforts Congressional Research Service 1 Why This Issue Is Important for Congress Active Protection Systems (APSs) are...of these systems are highly susceptible to “soft kill” APS, which underlies the importance of both soft and hard kill capabilities. 20 In addition

  11. GeoDCAT-AP: Use cases and open issues

    OpenAIRE

    PEREGO ANDREA; FRIIS-CHRISTENSEN Anders; Lutz, Michael

    2016-01-01

    This paper illustrates some issues and use cases identified during the design and implementation of GeoDCAT-AP, a metadata profile aiming to provide a representation of geospatial metadata compliant with the DCAT application profile for European data portals (DCAT-AP). In particular, the paper focuses on those issues that may have a possible relevance also outside the geospatial domain, covering topics concerning metadata profile-based negotiation, publishing metadata on the Web, represen...

  12. AP-102/104 Retrieval control system qualification test procedure

    Energy Technology Data Exchange (ETDEWEB)

    RIECK, C.A.

    1999-05-18

    This Qualification Test Procedure documents the results of the qualification testing that was performed on the Project W-211, ''Initial Tank Retrieval Systems,'' retrieval control system (RCS) for tanks 241-AP-102 and 241-AP-104. The results confirm that the RCS has been programmed correctly and that the two related hardware enclosures have been assembled in accordance with the design documents.

  13. THE FIRST STARS

    Directory of Open Access Journals (Sweden)

    Daniel J. Whalen

    2013-12-01

    Full Text Available Pop III stars are the key to the character of primeval galaxies, the first heavy elements, the onset of cosmological reionization, and the seeds of supermassive black holes. Unfortunately, in spite of their increasing sophistication, numerical models of Pop III star formation cannot yet predict the masses of the first stars. Because they also lie at the edge of the observable universe, individual Pop III stars will remain beyond the reach of observatories for decades to come, and so their properties are unknown. However, it will soon be possible to constrain their masses by direct detection of their supernovae, and by reconciling their nucleosynthetic yields to the chemical abundances measured in ancient metal-poor stars in the Galactic halo, some of which may bear the ashes of the first stars. Here, I review the state of the art in numerical simulations of primordial stars and attempts to directly and indirectly constrain their properties.

  14. Main-sequence variable stars in young open cluster NGC 1893

    OpenAIRE

    Lata, Sneh; Yadav, Ram Kesh; Pandey, A.K.(Indian Institute of Technology Bombay (IIT), Mumbai, India); Richichi, Andrea; Eswaraiah, C.; Kumar, Brajesh; Kappelmann, Norbert; Sharma, Saurabh

    2014-01-01

    In this paper we present time series photometry of 104 variable stars in the cluster region NGC 1893. The association of the present variable candidates to the cluster NGC 1893 has been determined by using $(U-B)/(B-V)$ and $(J-H)/(H-K)$ two colour diagrams, and $V/(V-I)$ colour magnitude diagram. Forty five stars are found to be main-sequence variables and these could be B-type variable stars associated with the cluster. We classified these objects as $\\beta$ Cep, slowly pulsating B stars an...

  15. TGF-beta and osteoarthritis.

    NARCIS (Netherlands)

    Blaney Davidson, E.N.; Kraan, P.M. van der; Berg, W.B. van den

    2007-01-01

    OBJECTIVE: Cartilage damage is a major problem in osteoarthritis (OA). Growth factors like transforming growth factor-beta (TGF-beta) have great potential in cartilage repair. In this review, we will focus on the potential therapeutic intervention in OA with TGF-beta, application of the growth facto

  16. AP1000模块化施工分析%Analysis of the AP1000 Modular Construction

    Institute of Scientific and Technical Information of China (English)

    邹玮

    2014-01-01

    文章针对AP1000机组模块化施工的技术和进度特点进行了分析,特别是对AP1000模块化施工面临的挑战和问题进行了深入的分析.这些挑战和问题有些是首台AP1000机组所特有的,有些将在后续AP1000机组建设过程中继续存在,文章分别阐述并提出了几项建议措施.

  17. Neutron Star Kicks and their Relationship to Supernovae Ejecta Mass

    CERN Document Server

    Bray, J C

    2016-01-01

    We propose a simple model to explain the velocity of young neutron stars. We attempt to confirm a relationship between the amount of mass ejected in the formation of the neutron star and the `kick' velocity imparted to the compact remnant resulting from the process. We assume the velocity is given by $v_{\\rm kick}=\\alpha\\,(M_{\\rm ejecta} / M_{\\rm remnant}) + \\beta\\,$. To test this simple relationship we use the BPASS (Binary Population and Spectral Synthesis) code to create stellar population models from both single and binary star evolutionary pathways. We then use our Remnant Ejecta and Progenitor Explosion Relationship (REAPER) code to apply different $\\alpha$ and $\\beta$ values and three different `kick' orientations then record the resulting velocity probability distributions. We find that while a single star population provides a poor fit to the observational data, the binary population provides an excellent fit. Values of $\\alpha=70\\, {\\rm km\\,s^{-1}}$ and $\\beta=110\\,{\\rm km\\,s^{-1}}$ reproduce the \\c...

  18. Data of evolutionary structure change: 1AP4A-1CLMA [Confc[Archive

    Lifescience Database Archive (English)

    Full Text Available 1AP4A-1CLMA 1AP4 1CLM A A ---------------------------------------...DDS LTEEQIAEFKEAFALFDKDGDGTITTKELGTVMRSLGQNPTEAELQDMINEVDADGNGTIDFPEFLSLMARKMKEQDSEEELIEAFKVFDR...36 1CLM A 1CLMA

  19. VizieR Online Data Catalog: Fundamental parameters of Kepler stars (Silva Aguirre+, 2015)

    Science.gov (United States)

    Silva Aguirre, V.; Davies, G. R.; Basu, S.; Christensen-Dalsgaard, J.; Creevey, O.; Metcalfe, T. S.; Bedding, T. R.; Casagrande, L.; Handberg, R.; Lund, M. N.; Nissen, P. E.; Chaplin, W. J.; Huber, D.; Serenelli, A. M.; Stello, D.; van Eylen, V.; Campante, T. L.; Elsworth, Y.; Gilliland, R. L.; Hekker, S.; Karoff, C.; Kawaler, S. D.; Kjeldsen, H.; Lundkvist, M. S.

    2016-02-01

    Our sample has been extracted from the 77 exoplanet host stars presented in Huber et al. (2013, Cat. J/ApJ/767/127). We have made use of the full time-base of observations from the Kepler satellite to uniformly determine precise fundamental stellar parameters, including ages, for a sample of exoplanet host stars where high-quality asteroseismic data were available. We devised a Bayesian procedure flexible in its input and applied it to different grids of models to study systematics from input physics and extract statistically robust properties for all stars. (4 data files).

  20. Differential regulation of chemoattractant-stimulated beta 2, beta 3, and beta 7 integrin activity.

    Science.gov (United States)

    Sadhu, C; Masinovsky, B; Staunton, D E

    1998-06-01

    Leukocyte adhesion to endothelium and extravasation are dynamic processes that require activation of integrins. Chemoattractants such as IL-8 and FMLP are potent activators of leukocyte integrins. To compare the chemoattractant-stimulated activation of three integrins, alpha 4 beta 7, alpha L beta 2, and alpha V beta 3, in the same cellular context, we expressed an IL-8 receptor (IL-8RA) and FMLP receptor (FPR) in the lymphoid cell line JY. Chemoattractants induced a rapid increase in alpha L beta 2- and alpha V beta 3-dependent JY adhesion within 5 min, and it was sustained for 30 min. In contrast, stimulation of alpha 4 beta 7-dependent adhesion was transient, returning to basal levels by 30 min. The activation profiles of the integrins were similar regardless of whether IL-8 or FMLP was used for induction. We also demonstrate that alpha 4 beta 7-dependent adhesion was uniquely responsive to the F actin-disrupting agent cytochalasin D and the protein kinase C (PKC) inhibitor chelerythrin. While alpha V beta 3- and alpha L beta 2-mediated cell adhesion was significantly reduced by cytochalasin D, alpha 4 beta 7-mediated adhesion was enhanced. Chelerythrin inhibited both the IL-8 and PMA activation of alpha L beta 2 and alpha V beta 3. In contrast, inducible alpha 4 beta 7 activity was unaffected, and basal activity was increased. These findings demonstrate that the mechanism of alpha 4 beta 7 regulation by chemoattractants is different from that of alpha L beta 2 and alpha V beta 3 and that it appears to involve distinct cytoskeletal and PKC dependencies. In addition, PKC activity may be a positive or negative regulator of integrin-dependent adhesion.

  1. Star Clusters within FIRE

    Science.gov (United States)

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

    2017-01-01

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

  2. Multiplicity of massive stars

    CERN Document Server

    Preibisch, T; Zinnecker, H; Preibisch, Thomas; Weigelt, Gerd; Zinnecker, Hans

    2000-01-01

    We discuss the observed multiplicity of massive stars and implications on theories of massive star formation. After a short summary of the literature on massive star multiplicity, we focus on the O- and B-type stars in the Orion Nebula Cluster, which constitute a homogenous sample of very young massive stars. 13 of these stars have recently been the targets of a bispectrum speckle interferometry survey for companions. Considering the visual and also the known spectroscopic companions of these stars, the total number of companions is at least 14. Extrapolation with correction for the unresolved systems suggests that there are at least 1.5 and perhaps as much as 4 companions per primary star on average. This number is clearly higher than the mean number of about 0.5 companions per primary star found for the low-mass stars in the general field population and also in the Orion Nebula cluster. This suggests that a different mechanism is at work in the formation of high-mass multiple systems in the dense Orion Nebu...

  3. Neutron stars and their magnetic fields

    CERN Document Server

    Reisenegger, Andreas

    2008-01-01

    Neutron stars have the strongest magnetic fields known anywhere in the Universe. In this review, I intend to give a pedagogical discussion of some of the related physics. Neutron stars exist because of Pauli's exclusion principle, in two senses: 1) It makes it difficult to squeeze particles too close together, in this way allowing a mechanical equilibrium state in the presence of extremely strong gravity. 2) The occupation of low-energy proton and electron states makes it impossible for low-energy neutrons to beta decay. A corollary of the second statement is that charged particles are necessarily present inside a neutron star, allowing currents to flow. Since these particles are degenerate, they collide very little, and therefore make it possible for the star to support strong, organized magnetic fields over long times. These show themselves in pulsars and are the most likely energy source for the high X-ray and gamma-ray luminosity ``magnetars''. I briefly discuss the possible origin of this field and some ...

  4. Metastable strange matter and compact quark stars

    CERN Document Server

    Malheiro, M; Taurines, A R

    2003-01-01

    Strange quark matter in beta equilibrium at high densities is studied in a quark confinement model. Two equations of state are dynamically generated for the {\\it same} set of model parameters used to describe the nucleon: one corresponds to a chiral restored phase with almost massless quarks and the other to a chiral broken phase. The chiral symmetric phase saturates at around five times the nuclear matter density. Using the equation of state for this phase, compact bare quark stars are obtained with radii and masses in the ranges $R\\sim 5 - 8$ km and $M\\sim M_\\odot$. The energy per baryon number decreases very slowly from the center of the star to the periphery, remaining above the corresponding values for the iron or the nuclear matter, even at the edge. Our results point out that strange quark matter at very high densities may not be absolutely stable and the existence of an energy barrier between the two phases may prevent the compact quarks stars to decay to hybrid stars.

  5. DNA cleavage at the AP site via β-elimination mediated by the AP site-binding ligands.

    Science.gov (United States)

    Abe, Yukiko S; Sasaki, Shigeki

    2016-02-15

    DNA is continuously damaged by endogenous and exogenous factors such as oxidation and alkylation. In the base excision repair pathway, the damaged nucleobases are removed by DNA N-glycosylase to form the abasic sites (AP sites). The alkylating antitumor agent exhibits cytotoxicity through the formation of the AP site. Therefore blockage or modulation of the AP site repair pathway may enhance the antitumor efficacy of DNA alkylating agents. In this study, we have examined the effects of the nucleobase-polyamine conjugated ligands (G-, A-, C- and T-ligands) on the cleavage of the AP site. The G- and A-ligands cleaved DNA at the AP site by promoting β-elimination in a non-selective manner by the G-ligand, and in a selective manner for the opposing dT by the A-ligand. These results suggest that the nucleobase-polyamine conjugate ligands may have the potential for enhancement of the cytotoxicities of the AP site.

  6. VizieR Online Data Catalog: High quality Spitzer/MIPS obs. of F4-K2 stars (Sierchio+, 2014)

    Science.gov (United States)

    Sierchio, J. M.; Rieke, G. H.; Su, K. Y. L.; Gaspar, A.

    2016-11-01

    We used specific criteria to draw samples of stars from the entire Spitzer Debris Disk Database (see section 2.1.1). V magnitudes were taken from Hipparcos and transformed to Johnson V. All stars were also required to have observations on the Two Micron All Sky Survey (2MASS) Ks system. Additional measurements were obtained at SAAO on the 0.75m telescope using the MarkII Infrared Photometer (transformed as described by Koen et al. 2007MNRAS.380.1433K), and at the Steward Observatory 61 in telescope using a NICMOS2-based camera with a 2MASS filter set and a neutral density filter to avoid saturation. These measurements will be described in a forthcoming paper (K. Y. L. Su et al., in preparation). The original programs in which our sample stars were measured are identified in Table 1. A large majority (93%) come from seven Spitzer programs: (1) the MIPS Guaranteed Time Observer (GTO) Sun-like star observations (Trilling+ 2008ApJ...674.1086T); (2) Formation and Evolution of Planetary Systems (FEPS; Meyer+ 2006, J/PASP/118/1690); (3) Completing the Census of Debris Disks (Koerner+ 2010ApJ...710L..26K); (4) potential Space Interferometry Mission/Terrestrial Planet Finder (SIM/TPF) targets (Beichman+ 2006ApJ...652.1674B); (5) an unbiased sample of F-stars (Trilling+ 2008ApJ...674.1086T); and (6) two coordinated programs selecting stars on the basis of indicators of youth (Low+ 2005ApJ...631.1170L; Plavchan+ 2009ApJ...698.1068P). See section 2.1.2. (1 data file).

  7. Dark stars: a review.

    Science.gov (United States)

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

    2016-06-01

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

  8. Dark stars: a review

    Science.gov (United States)

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

    2016-06-01

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

  9. Star-Branched Polymers (Star Polymers)

    KAUST Repository

    Hirao, Akira

    2015-09-01

    The synthesis of well-defined regular and asymmetric mixed arm (hereinafter miktoarm) star-branched polymers by the living anionic polymerization is reviewed in this chapter. In particular, much attention is being devoted to the synthetic development of miktoarm star polymers since 2000. At the present time, the almost all types of multiarmed and multicomponent miktoarm star polymers have become feasible by using recently developed iterative strategy. For example, the following well-defined stars have been successfully synthesized: 3-arm ABC, 4-arm ABCD, 5-arm ABCDE, 6-arm ABCDEF, 7-arm ABCDEFG, 6-arm ABC, 9-arm ABC, 12-arm ABC, 13-arm ABCD, 9-arm AB, 17-arm AB, 33-arm AB, 7-arm ABC, 15-arm ABCD, and 31-arm ABCDE miktoarm star polymers, most of which are quite new and difficult to synthesize by the end of the 1990s. Several new specialty functional star polymers composed of vinyl polymer segments and rigid rodlike poly(acetylene) arms, helical polypeptide, or helical poly(hexyl isocyanate) arms are introduced.

  10. Touchstone Stars: Highlights from the Cool Stars 18 Splinter Session

    CERN Document Server

    Mann, Andrew W; Boyajian, Tabetha; Gaidos, Eric; von Braun, Kaspar; Feiden, Gregory A; Metcalfe, Travis; Swift, Jonathan J; Curtis, Jason L; Deacon, Niall R; Filippazzo, Joseph C; Gillen, Ed; Hejazi, Neda; Newton, Elisabeth R

    2014-01-01

    We present a summary of the splinter session on "touchstone stars" -- stars with directly measured parameters -- that was organized as part of the Cool Stars 18 conference. We discuss several methods to precisely determine cool star properties such as masses and radii from eclipsing binaries, and radii and effective temperatures from interferometry. We highlight recent results in identifying and measuring parameters for touchstone stars, and ongoing efforts to use touchstone stars to determine parameters for other stars. We conclude by comparing the results of touchstone stars with cool star models, noting some unusual patterns in the differences.

  11. An AP4B1 frameshift mutation in siblings with intellectual disability and spastic tetraplegia further delineates the AP-4 deficiency syndrome.

    Science.gov (United States)

    Abdollahpour, Hengameh; Alawi, Malik; Kortüm, Fanny; Beckstette, Michael; Seemanova, Eva; Komárek, Vladimír; Rosenberger, Georg; Kutsche, Kerstin

    2015-02-01

    The recently proposed adaptor protein 4 (AP-4) deficiency syndrome comprises a group of congenital neurological disorders characterized by severe intellectual disability (ID), delayed or absent speech, hereditary spastic paraplegia, and growth retardation. AP-4 is a heterotetrameric protein complex with important functions in vesicle trafficking. Mutations in genes affecting different subunits of AP-4, including AP4B1, AP4E1, AP4S1, and AP4M1, have been reported in patients with the AP-4 deficiency phenotype. We describe two siblings from a non-consanguineous couple who presented with severe ID, absent speech, microcephaly, growth retardation, and progressive spastic tetraplegia. Whole-exome sequencing in the two patients identified the novel homozygous 2-bp deletion c.1160_1161delCA (p.(Thr387Argfs*30)) in AP4B1. Sanger sequencing confirmed the mutation in the siblings and revealed it in the heterozygous state in both parents. The AP4B1-associated phenotype has previously been assigned to spastic paraplegia-47. Identification of a novel AP4B1 alteration in two patients with clinical manifestations highly similar to other individuals with mutations affecting one of the four AP-4 subunits further supports the observation that loss of AP-4 assembly or functionality underlies the common clinical features in these patients and underscores the existence of the clinically recognizable AP-4 deficiency syndrome.

  12. Beta-thalassemia

    Directory of Open Access Journals (Sweden)

    Origa Raffaella

    2010-05-01

    Full Text Available Abstract Beta-thalassemias are a group of hereditary blood disorders characterized by anomalies in the synthesis of the beta chains of hemoglobin resulting in variable phenotypes ranging from severe anemia to clinically asymptomatic individuals. The total annual incidence of symptomatic individuals is estimated at 1 in 100,000 throughout the world and 1 in 10,000 people in the European Union. Three main forms have been described: thalassemia major, thalassemia intermedia and thalassemia minor. Individuals with thalassemia major usually present within the first two years of life with severe anemia, requiring regular red blood cell (RBC transfusions. Findings in untreated or poorly transfused individuals with thalassemia major, as seen in some developing countries, are growth retardation, pallor, jaundice, poor musculature, hepatosplenomegaly, leg ulcers, development of masses from extramedullary hematopoiesis, and skeletal changes that result from expansion of the bone marrow. Regular transfusion therapy leads to iron overload-related complications including endocrine complication (growth retardation, failure of sexual maturation, diabetes mellitus, and insufficiency of the parathyroid, thyroid, pituitary, and less commonly, adrenal glands, dilated myocardiopathy, liver fibrosis and cirrhosis. Patients with thalassemia intermedia present later in life with moderate anemia and do not require regular transfusions. Main clinical features in these patients are hypertrophy of erythroid marrow with medullary and extramedullary hematopoiesis and its complications (osteoporosis, masses of erythropoietic tissue that primarily affect the spleen, liver, lymph nodes, chest and spine, and bone deformities and typical facial changes, gallstones, painful leg ulcers and increased predisposition to thrombosis. Thalassemia minor is clinically asymptomatic but some subjects may have moderate anemia. Beta-thalassemias are caused by point mutations or, more rarely

  13. Beta-thalassemia.

    Science.gov (United States)

    Galanello, Renzo; Origa, Raffaella

    2010-05-21

    Beta-thalassemias are a group of hereditary blood disorders characterized by anomalies in the synthesis of the beta chains of hemoglobin resulting in variable phenotypes ranging from severe anemia to clinically asymptomatic individuals. The total annual incidence of symptomatic individuals is estimated at 1 in 100,000 throughout the world and 1 in 10,000 people in the European Union. Three main forms have been described: thalassemia major, thalassemia intermedia and thalassemia minor. Individuals with thalassemia major usually present within the first two years of life with severe anemia, requiring regular red blood cell (RBC) transfusions. Findings in untreated or poorly transfused individuals with thalassemia major, as seen in some developing countries, are growth retardation, pallor, jaundice, poor musculature, hepatosplenomegaly, leg ulcers, development of masses from extramedullary hematopoiesis, and skeletal changes that result from expansion of the bone marrow. Regular transfusion therapy leads to iron overload-related complications including endocrine complication (growth retardation, failure of sexual maturation, diabetes mellitus, and insufficiency of the parathyroid, thyroid, pituitary, and less commonly, adrenal glands), dilated myocardiopathy, liver fibrosis and cirrhosis). Patients with thalassemia intermedia present later in life with moderate anemia and do not require regular transfusions. Main clinical features in these patients are hypertrophy of erythroid marrow with medullary and extramedullary hematopoiesis and its complications (osteoporosis, masses of erythropoietic tissue that primarily affect the spleen, liver, lymph nodes, chest and spine, and bone deformities and typical facial changes), gallstones, painful leg ulcers and increased predisposition to thrombosis. Thalassemia minor is clinically asymptomatic but some subjects may have moderate anemia. Beta-thalassemias are caused by point mutations or, more rarely, deletions in the beta

  14. Beta and muon decays

    Energy Technology Data Exchange (ETDEWEB)

    Galindo, A.; Pascual, P.

    1967-07-01

    These notes represent a series of lectures delivered by the authors in the Junta de Energia Nuclear, during the Spring term of 1965. They were devoted to graduate students interested in the Theory of Elementary Particles. Special emphasis was focussed into the computational problems. Chapter I is a review of basic principles (Dirac equation, transition probabilities, final state interactions.) which will be needed later. In Chapter II the four-fermion punctual Interaction is discussed, Chapter III is devoted to the study of beta-decay; the main emphasis is given to the deduction of the formulae corresponding to electron-antineutrino correlation, electron energy spectrum, lifetimes, asymmetry of electrons emitted from polarized nuclei, electron and neutrino polarization and time reversal invariance in beta decay. In Chapter IV we deal with the decay of polarized muons with radiative corrections. Chapter V is devoted to an introduction to C.V.C. theory. (Author)

  15. Realized Beta GARCH

    DEFF Research Database (Denmark)

    Hansen, Peter Reinhard; Lunde, Asger; Voev, Valeri Radkov

    2014-01-01

    We introduce a multivariate generalized autoregressive conditional heteroskedasticity (GARCH) model that incorporates realized measures of variances and covariances. Realized measures extract information about the current levels of volatilities and correlations from high-frequency data, which...... is particularly useful for modeling financial returns during periods of rapid changes in the underlying covariance structure. When applied to market returns in conjunction with returns on an individual asset, the model yields a dynamic model specification of the conditional regression coefficient that is known...... as the beta. We apply the model to a large set of assets and find the conditional betas to be far more variable than usually found with rolling-window regressions based exclusively on daily returns. In the empirical part of the paper, we examine the cross-sectional as well as the time variation...

  16. Magic Baseline Beta Beam

    CERN Document Server

    Agarwalla, Sanjib Kumar; Raychaudhuri, Amitava

    2007-01-01

    We study the physics reach of an experiment where neutrinos produced in a beta-beam facility at CERN are observed in a large magnetized iron calorimeter (ICAL) at the India-based Neutrino Observatory (INO). The CERN-INO distance is close to the so-called "magic" baseline which helps evade some of the parameter degeneracies and allows for a better measurement of the neutrino mass hierarchy and $\\theta_{13}$.

  17. Beta cell adaptation in pregnancy

    DEFF Research Database (Denmark)

    Nielsen, Jens Høiriis

    2016-01-01

    Pregnancy is associated with a compensatory increase in beta cell mass. It is well established that somatolactogenic hormones contribute to the expansion both indirectly by their insulin antagonistic effects and directly by their mitogenic effects on the beta cells via receptors for prolactin...... and growth hormone expressed in rodent beta cells. However, the beta cell expansion in human pregnancy seems to occur by neogenesis of beta cells from putative progenitor cells rather than by proliferation of existing beta cells. Claes Hellerström has pioneered the research on beta cell growth for decades......, but the mechanisms involved are still not clarified. In this review the information obtained in previous studies is recapitulated together with some of the current attempts to resolve the controversy in the field: identification of the putative progenitor cells, identification of the factors involved...

  18. Regulation of beta cell replication

    DEFF Research Database (Denmark)

    Lee, Ying C; Nielsen, Jens Høiriis

    2008-01-01

    Beta cell mass, at any given time, is governed by cell differentiation, neogenesis, increased or decreased cell size (cell hypertrophy or atrophy), cell death (apoptosis), and beta cell proliferation. Nutrients, hormones and growth factors coupled with their signalling intermediates have been...... suggested to play a role in beta cell mass regulation. In addition, genetic mouse model studies have indicated that cyclins and cyclin-dependent kinases that determine cell cycle progression are involved in beta cell replication, and more recently, menin in association with cyclin-dependent kinase...... inhibitors has been demonstrated to be important in beta cell growth. In this review, we consider and highlight some aspects of cell cycle regulation in relation to beta cell replication. The role of cell cycle regulation in beta cell replication is mostly from studies in rodent models, but whether...

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

    Science.gov (United States)

    Hira, Ravi S; Dean, Larry S

    2016-04-01

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

  20. The First Stars

    Science.gov (United States)

    Yoshida, Naoki

    2010-10-01

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

  1. Kinematics and chemistry of faint high latitude dwarf carbon stars

    Science.gov (United States)

    Yoon, Jinmi; Beers, Timothy C.; Dietz, Sarah; Lee, Young Sun; Placco, Vinicius M.

    2017-01-01

    The diffuse halo system of the Milky Way is complex, and has been shown to comprise at least two main components: a near-zero net rotation inner-halo and a more rapidly rotating outer-halo component. Studies of the ancient, very metal-poor stars in the Galactic halo system are crucial for understanding its early formation history. The so-called carbon-enhanced metal-poor (CEMP) stars are an important subset of the stars in the halo system, which exhibit distinctive kinematic and chemical signatures that can be used to constrain the star-formation histories and assembly of the various Galactic components.We have examined the sample of main-sequence dwarf and other faint high Galactic latitude carbon-enhanced stars from the Sloan Digital Sky Survey studied by Green (2013). As noted by Green, many of these starsexhibit high proper motions, which have been later claimed to be related to possible binary ejection models Plant et al. (2016). By use of the CEMP sub-classification approach of Yoon et al. (2016), we investigate whether the kinematics of these stars might instead result from their membership in the inner/outer halo populations of the Galaxy.ReferencesGreen, P. 2013, ApJ, 765, 12Plant, K. et al. 2016, AAS 227.34115Yoon, J. et al. 2016, ApJ, in pressAcknowledgementThis work was supported in part by the National Science Foundation under Grant No. PHY-1430152 (JINA Center for the Evolution of the Elements).

  2. LHCb: $2\\beta_s$ measurement at LHCb

    CERN Multimedia

    Conti, G

    2009-01-01

    A measurement of $2\\beta_s$, the phase of the $B_s-\\bar{B_s}$ oscillation amplitude with respect to that of the ${\\rm b} \\rightarrow {\\rm c^{+}}{\\rm W^{-}}$ tree decay amplitude, is one of the key goals of the LHCb experiment with first data. In the Standard Model (SM), $2\\beta_s$ is predicted to be $0.0360^{+0.0020}_{-0.0016} \\rm rad$. The current constraints from the Tevatron are: $2\\beta_{s}\\in[0.32 ; 2.82]$ at 68$\\%$CL from the CDF experiment and $2\\beta_{s}=0.57^{+0.24}_{-0.30}$ from the D$\\oslash$ experiment. Although the statistical uncertainties are large, these results hint at the possible contribution of New Physics in the $B_s-\\bar{B_s}$ box diagram. After one year of data taking at LHCb at an average luminosity of $\\mathcal{L}\\sim2\\cdot10^{32}\\rm cm^{-2} \\rm s^{-1}$ (integrated luminosity $\\mathcal{L}_{\\rm int}\\sim 2 \\rm fb^{-1}$), the expected statistical uncertainty on the measurement is $\\sigma(2\\beta_s)\\simeq 0.03$. This uncertainty is similar to the $2\\beta_s$ value predicted by the SM.

  3. Project Runaway: Calibrating the Spectroscopic Distance Scale Using Runaway O and Wolf-Rayet Stars

    Science.gov (United States)

    Hartkopf, William I.; Mason, B. D.

    2009-05-01

    Well-determined O star masses are notoriously difficult to obtain, due to such factors as broad spectral lines, larger and less-reliable average distances, high multiplicity rates, crowded fields, and surrounding nebulosity. Some of these difficulties are reduced for the subset of O stars known as runaways, however. They have escaped some of the nebulosity and crowding, and the event leading to their ejection virtually guarantees that these objects are either single stars or extremely hard spectroscopic binaries. The goal of this project is to increase the sample of known runaway stars, using updated proper motions from the soon-to-be-released UCAC3 catalog, as well as published radial velocities and data from recent duplicity surveys of massive stars using AO and speckle interferometry. Input files include the Galactic O Star Catalog of Maiz-Apellaniz et al. (2004 ApJSS 151, 103) as well as the Seventh Catalogue of Galactic Wolf-Rayet Stars and its more recent Annex (van der Hucht 2001 NewAR 45, 135; 2006 A&A 458, 453). The new runaway star sample will form the basis for a list of SIM targets aimed at improving the distances of Galactic O and WR stars, calibrating the spectroscopic distance scale and leading to more accurate mass estimates for these massive stars.

  4. Strange nonchaotic stars

    CERN Document Server

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

    2015-01-01

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

  5. Membrane anchor R9AP potentiates GTPase-accelerating protein activity of RGS11 x Gbeta5 complex and accelerates inactivation of the mGluR6-G(o) signaling.

    Science.gov (United States)

    Masuho, Ikuo; Celver, Jeremy; Kovoor, Abraham; Martemyanov, Kirill A

    2010-02-12

    The R7 subfamily of RGS proteins critically regulates neuronal G protein-signaling pathways that are essential for vision, nociception, motor coordination, and reward processing. A member of the R7 RGS family, RGS11, is a GTPase-accelerating protein specifically expressed in retinal ON-bipolar cells where it forms complexes with the atypical G protein beta subunit, Gbeta(5), and transmembrane protein R9AP. Association with R9AP has been shown to be critical for the proteolytic stability of the complex in the retina. In this study we report that R9AP can in addition stimulate the GTPase-accelerating protein activity of the RGS11 x Gbeta(5) complex at Galpha(o). Single turnover GTPase assays reveal that R9AP co-localizes RGS11 x Gbeta(5) and Galpha(o) on the membrane and allosterically potentiates the GTPase-accelerating function of RGS11 x Gbeta(5). Reconstitution of mGluR6-Galpha(o) signaling in Xenopus oocytes indicates that RGS11 x Gbeta(5)-mediated GTPase acceleration in this system requires co-expression of R9AP. The results provide new insight into the regulation of mGluR6-Galpha(o) signaling by the RGS11 x Gbeta(5) x R9AP complex and establish R9AP as a general GTPase-accelerating protein activity regulator of R7 RGS complexes.

  6. RELATIVISTIC SUPERNOVAE HAVE SHORTER-LIVED CENTRAL ENGINES OR MORE EXTENDED PROGENITORS: THE CASE OF SN 2012ap

    Energy Technology Data Exchange (ETDEWEB)

    Margutti, R.; Milisavljevic, D.; Soderberg, A. M.; Sanders, N.; Chakraborti, S.; Kamble, A.; Drout, M.; Parrent, J.; Zauderer, A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Guidorzi, C. [Department of Physics and Earth Sciences, University of Ferrara, via Saragat 1, I-44122 Ferrara (Italy); Morsony, B. J. [Department of Astronomy, University of Wisconsin-Madison, 2535 Sterling Hall, 475 North Charter Street, Madison, WI 53706-1582 (United States); Ray, A. [Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400 005 (India); Chomiuk, L. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)

    2014-12-20

    Deep, late-time X-ray observations of the relativistic, engine-driven, type Ic SN 2012ap allow us to probe the nearby environment of the explosion and reveal the unique properties of relativistic supernova explosions (SNe). We find that on a local scale of ∼0.01 pc the environment was shaped directly by the evolution of the progenitor star with a pre-explosion mass-loss rate of M-dot <5×10{sup −6} M{sub ⊙} yr{sup −1}, in line with gamma-ray bursts (GRBs) and the other relativistic SN 2009bb. Like sub-energetic GRBs, SN 2012ap is characterized by a bright radio emission and evidence for mildly relativistic ejecta. However, its late-time (δt ≈ 20 days) X-ray emission is ∼100 times fainter than the faintest sub-energetic GRB at the same epoch, with no evidence for late-time central engine activity. These results support theoretical proposals that link relativistic SNe like 2009bb and 2012ap with the weakest observed engine-driven explosions, where the jet barely fails to break out. Furthermore, our observations demonstrate that the difference between relativistic SNe and sub-energetic GRBs is intrinsic and not due to line-of-sight effects. This phenomenology can either be due to an intrinsically shorter-lived engine or to a more extended progenitor in relativistic SNe.

  7. Making Stars … With a Little Help

    Science.gov (United States)

    Kohler, Susanna

    2015-11-01

    in all cases, the presence of external pressure causes the star formation rates to be significantly higher than in the cases with no feedback. For galaxies that contain a high gas fraction, this difference is especially pronounced at early times; the external pressure causes gas to fragment into clumps that are dense enough to form stars much sooner than in the absence of pressure.Bieri and collaborators also track the mass entering and leaving the galactic disk during the simulation. When external pressure is present, it drives a large net mass inflow at the beginning of the simulation, carrying in material from the halo and outer disk. This early source of mass helps to feed cloud and clump growth in the inner parts of the galaxy contributing to the increased star formation rate in the pressurized cases.Thus, this simple model has demonstrated that enhanced pressure due to AGN feedback is an effective means of explaining the large star formation rates we observe in high-redshift galaxies.CitationRebekka Bieri et al 2015 ApJ 812 L36. doi:10.1088/2041-8205/812/2/L36

  8. Interacting binary stars

    CERN Document Server

    Sahade, Jorge; Ter Haar, D

    1978-01-01

    Interacting Binary Stars deals with the development, ideas, and problems in the study of interacting binary stars. The book consolidates the information that is scattered over many publications and papers and gives an account of important discoveries with relevant historical background. Chapters are devoted to the presentation and discussion of the different facets of the field, such as historical account of the development in the field of study of binary stars; the Roche equipotential surfaces; methods and techniques in space astronomy; and enumeration of binary star systems that are studied

  9. Strange Nonchaotic Stars

    Science.gov (United States)

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

    2015-08-01

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

  10. ENERGY STAR Unit Reports

    Data.gov (United States)

    Department of Housing and Urban Development — These quarterly Federal Fiscal Year performance reports track the ENERGY STAR qualified HOME units that Participating Jurisdictions record in HUD's Integrated...

  11. Horizontal Branch stars as AmFm/HgMn stars

    CERN Document Server

    Michaud, G

    2008-01-01

    Recent observations and models for horizontal branch stars are briefly described and compared to models for AmFm stars. The limitations of those models are emphasized by a comparison to observations and models for HgMn stars.

  12. Oscillations in Beta UMi - Observations with SMEI

    CERN Document Server

    Tarrant, N J; Elsworth, Y; Spreckley, S A; Stevens, I R

    2008-01-01

    Aims: From observations of the K4III star Beta UMi we attempt to determine whether oscillations or any other form of variability is present. Methods: A high-quality photometric time series of approximately 1000 days in length obtained from the SMEI instrument on the Coriolis satellite is analysed. Various statistical tests were performed to determine the significance of features seen in the power density spectrum of the light curve. Results: Two oscillations with frequencies 2.44 and 2.92 microhertz have been identified. We interpret these oscillations as consecutive overtones of an acoustic spectrum, implying a large frequency spacing of 0.48 microhertz. Using derived asteroseismic parameters in combination with known astrophysical parameters, we estimate the mass of Beta UMi to be 1.3 +/- 0.3 solar masses. Peaks of the oscillations in the power density spectrum show width, implying that modes are stochastically excited and damped by convection. The mode lifetime is estimated at 18 +/- 9 days.

  13. 3D-HST Emission Line Galaxies at z ~ 2: Discrepancies in the Optical/UV Star Formation Rates

    CERN Document Server

    Zeimann, Gregory R; Gebhardt, Henry; Gronwall, Caryl; Schneider, Donald P; Hagen, Alex; Bridge, Joanna S; Feldmeier, John; Trump, Jonathan R

    2014-01-01

    We use Hubble Space Telescope near-IR grism spectroscopy to examine the H-beta line strengths of 260 star-forming galaxies in the redshift range 1.90 < z < 2.35. We show that at these epochs, the H-beta star formation rate (SFR) is a factor of ~1.8 higher than what would be expected from the systems' rest-frame UV flux density, suggesting a shift in the standard conversion between these quantities and star formation rate. We demonstrate that at least part of this shift can be attributed to metallicity, as H-beta is more greatly enhanced in systems with lower oxygen abundance. This offset must be considered when measuring the star formation rate history of the universe. We also show that the relation between stellar and nebular extinction in our z ~ 2 sample is consistent with that observed in the local universe.

  14. Prevention of aspiration pneumonia (AP) with oral care.

    Science.gov (United States)

    Tada, Akio; Miura, Hiroko

    2012-01-01

    AP is a major cause of morbidity and mortality in elderly patients, especially frail elderly patients. The aim of this article is to review effect of oral care, including oral hygiene and improvement of oral function, on the prevention of AP among elderly people in hospitals and nursing homes. There is now a substantial body of work studying the effect of oral care on the prevention of respiratory diseases. Oral hygiene, consisting of oral decontamination and mechanical cleaning by dental professionals, has resulted in significant clinical effects (decreased incidence of pneumonia and decreased mortality from respiratory diseases) in clinical randomized trials. Moreover, studies examining oral colonization by pneumonia pathogens have shown the effect of oral hygiene on eliminating these pathogens. In addition, swallowing training has been shown to improve the movement and function of swallowing-related muscles, also resulting in decreased incidence of pneumonia. These findings support the contention that oral care is effective in the prevention of AP.

  15. Westinghouse plans global new builds for AP1000

    Energy Technology Data Exchange (ETDEWEB)

    Mitev, Lubomir [NucNet, Brussels (Belgium)

    2014-10-15

    Interview with Danny Roderick, Westinghouse Electric Company, President and Chief Executive Officer since September 2012, about perspectives and future plans for AP1000 new build worldwide. Within three to four years there wille be 'shovels in the ground' for three new AP1000 reactors in the UK, as well as new units in China and Bulgaria. Four AP1000 reactors are under construction in the United States at Vogtle and VC Summer, and soon at Turkey Point. Additionally Danny Roderick spoke about the acquisition of NuGen, technology transfer, the influence of the Ukraine crises on the nuclear market in East Europe and the future need for more nuclear worldwide and in the UK and Bulgaria.

  16. Star Trek in the Schools

    Science.gov (United States)

    Journal of Aerospace Education, 1977

    1977-01-01

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

  17. Stars and Flowers, Flowers and Stars

    Science.gov (United States)

    Minti, Hari

    2012-12-01

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

  18. THE PARALLEL RECURSIVE AP ADAPTIVE ALGORITHM BASED ON VOLTERRA SERIES

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Aiming at the nonlinear system identification problem, a parallel recursive affine projection (AP) adaptive algorithm for the nonlinear system based on Volterra series is presented in this paper. The algorithm identifies in parallel the Volterra kernel of each order, recursively estimate the inverse of the autocorrelation matrix for the Volterra input of each order, and remarkably improve the convergence speed of the identification process compared with the NLMS and conventional AP adaptive algorithm based on Volterra series. Simulation results indicate that the proposed method in this paper is efficient.

  19. Physical and orbital properties of Beta Pictoris b

    CERN Document Server

    Bonnefoy, M; Galicher, R; Beust, H; Lagrange, A -M; Baudino, J -L; Chauvin, G; Borgniet, S; Meunier, N; Rameau, J; Boccaletti, A; Cumming, A; Helling, C; Homeier, D; Allard, F; Delorme, P

    2014-01-01

    The intermediate-mass star Beta Pictoris is known to be surrounded by a structured edge-on debris disk within which a gas giant planet was discovered orbiting at 8-10 AU. The physical properties of Beta Pic b were previously inferred from broad and narrow-band 0.9-4.8 microns photometry. We used commissioning data of the Gemini Planet Imager (GPI) to obtain new astrometry and a low-resolution (R=35-39) J-band (1.12-1.35 microns) spectrum of the planet. We find that the planet has passed the quadrature. We constrain its semi-major axis to $\\leq$ 10 AU (90 % prob.) with a peak at 8.9+0.4-0.6 AU. The joint fit of the planet astrometry and the most recent radial velocity measurements of the star yields a planet's dynamical mass $\\leq$ 20 MJup (greater than 96 % prob.). The extracted spectrum of Beta Pic b is similar to those of young L1-1.5+1 dwarfs. We use the spectral type estimate to revise the planet luminosity to log(L/Lsun)=-3.90+-0.07. The 0.9-4.8 microns photometry and spectrum are reproduced for Teff=165...

  20. High Dispersion Spectroscopy of Solar-Type Superflare Stars With Subaru/HDS

    Science.gov (United States)

    Notsu, Yuta; Honda, Satoshi; Maehara, Hiroyuki; Notsu, Shota; Shibayama, Takuya; Namekata, Kosuke; Nogami, Daisaku; Shibata, Kazunari

    2016-07-01

    Superflares are flares that release total energy 10-104times greater than that of the biggest solar flares ( 1032 erg). Recent Kepler-space-telescope observations found more than 1000superflares on a few hundred solar-type stars (Maehara et al. 2012, Nature; Shibayama et al. 2013, ApJS, Maehara et al. 2015 EPS).Suchsuperflare stars show quasi-periodicbrightnessvariations with the typical period of from one to a few tens of days. Such variations are thought to be caused by the rotation of the star with large starspots (Notsu et al. 2013, ApJ). However, spectroscopic observations are needed in order to confirm whether the variation is really due to the rotation and whether superflares can occur on ordinary single stars similar to our Sun.Then we have carried out spectroscopic observations for 50 solar-type superflare stars with Subaru/HDS (Notsu et al. 2015a&b, PASJ). As a result, more than half (34 stars) of the targetstars show no evidence of binarity, and the atmospheric parameters of these stars are in the range of solar-type stars.The detailed analyses for these 34 stars show that (1) the projected rotational velocities (v sin i) are consistent with the rotational velocities estimated from the brightness variations, (2)there is a correlation between the brightness variation amplitude and the intensity of Ca II IR triplet line. These results support that the brightness variation discussed above is explained bythe rotation of a star with large starspots. (The contents of this poster were already summarized in the proceeding of IAU Symposium S320 (Notsu et al. 2016 IAUS in press, arXiv:1510.08143))

  1. New Photometrically Variable Magnetic Chemically Peculiar Stars in the ASAS-3 Archive

    Science.gov (United States)

    Hümmerich, Stefan; Paunzen, Ernst; Bernhard, Klaus

    2016-10-01

    The magnetic Ap or CP2 stars are natural atomic and magnetic laboratories. Strictly periodic changes are observed in the spectra and brightness of these stars, which allow the derivation of rotational periods. Related to this group of objects are the He-weak (CP4) and He-rich stars, some of which also undergo brightness changes due to rotational modulation. Increasing the sample size of known rotational periods among CP2/4 stars is important and will contribute to our understanding of these objects and their evolution in time. We have compiled an extensive target list of CP2/4 stars from the General Catalog of Ap, HgMn, and Am stars, including several early-type (spectral types B/A) variables of undetermined type from the International Variable Star Index. We investigated our sample stars using publicly available observations from the ASAS-3 archive. Our previous efforts in this respect led to the discovery of 323 variable stars. Using a refined analysis approach, we were able to identify another 360 stars exhibiting photometric variability in ASAS-3 data. Summary data, folded light curves and, if available, information from the literature are presented for our final sample, which is composed of 334 bona-fide {α }2 Canum Venaticorum (ACV) variables, 23 ACV candidates, and 3 eclipsing binary systems. Interesting and unusual objects are discussed in detail. In particular, we call attention to HD 66051 (V414 Pup), which is an eclipsing binary system showing obvious rotational modulation of the light curve due to the presence of an ACV variable in the system.

  2. Star Formation Law in the Milky Way

    CERN Document Server

    Sofue, Yoshiaki

    2016-01-01

    The Schmidt law (SF law) in the Milky Way was investigated using 3D distribution maps of HII regions, HI and molecular (\\Htwo) gases with spatial resolutions of $\\sim 1$ kpc in the Galactic plane and a few tens of pc in the vertical direction. HII regions were shown to be distributed in a star-forming (SF) disk with nearly constant vertical full thickness 92 pc in spatial coincidence with the molecular gas disk. The vertically averaged volume star formation rate (SFR) $\\rho_{\\rm SFR}$ in the SF disk is related to the surface SFR $\\Sigma_{\\rm SFR}$ by $\\rho_{\\rm SFR} /[{\\rm M_\\odot y^{-1} kpc^{-3}}] =9.26\\times \\Sigma_{\\rm SFR}/[{\\rm M_\\odot y^{-1} kpc^{-2}}]$. The SF law fitted by a single power law of gas density in the form of $\\Sigma_{\\rm SFR} \\propto \\rho_{\\rm SFR} \\propto \\rho_{\\rm gas}^\\alpha$ and $\\propto \\Sigma_{\\rm gas}^\\beta$ showed indices of $\\alpha=0.78 \\pm 0.05$ for $\\rho_{\\rm H_2}$ and $2.15 \\pm 0.08$ for $\\rho_{\\rm total}$, and $\\beta=1.14\\pm 0.23$ for $\\Sigma_{\\rm total}$, where $\\rho$ and $\\...

  3. PAHs and star formation

    NARCIS (Netherlands)

    Tielens, AGGM; Peeters, E; Bakes, ELO; Spoon, HWW; Hony, S; Johnstone, D; Adams, FC; Lin, DNC; Neufeld, DA; Ostriker, EC

    2004-01-01

    Strong IR emission features at 3.3, 6.2, 7.7, 8.6, and 11.2 mum are a common characteristic of regions of massive star formation. These features are carried by large (similar to 50 C-atom) Polycyclic Aromatic Hydrocarbon molecules which are pumped by the strong FUV photon flux from these stars. Thes

  4. Observing Double Stars

    Science.gov (United States)

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

    2012-05-01

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

  5. Exploring the Birth of Binary Stars

    Science.gov (United States)

    Kohler, Susanna

    2016-08-01

    understand the alignment of protostellar outflows during binary formation, Offner and collaborators conduct a series of numerical simulations of the process of turbulent fragmentation.The teams radiation-magnetohydrodynamics simulations start with a spherical core with random turbulent velocities within it. The simulations then follow the formation of seeds within the core, which accrete mass and eventually launch protostellar outflows.In total, Offner and collaborators run twelve simulations, in which five produce single stars, five produce binaries, and two produce triplestar systems.Comparison to ObservationsCumulative density function of the angles between simulated binary pairs protostellar outflows. The black line is the MASSES data (observations of actual binaries). The alignments from the simulations are consistent with the real observational data. [Offner et al. 2016]As a final step, the authors generate synthetic observations from their simulations, to demonstrate what the protostellar outflows would look like. They then compare these to real observations of outflow orientations in young binaries from a survey known as MASSES.Statistical analysis shows that the protostellar jets in the authors simulations are consistent with being randomly aligned or misaligned. This confirms what we would expect since the systems formed at wide separations from separate gravitational collapse events and the alignment distribution is consistent with observations of binaries in MASSES.Offner and collaborators work in this study indicates that the presence of misaligned binaries in observations supports turbulent fragmentation as the mechanism for binary formation. The authors caution, however, that were dealing with small-number statistics: MASSES consists of only 19 binary pairs. The next step is to obtain a larger sample of observations for comparison.CitationStella S. R. Offner et al 2016 ApJ 827 L11. doi:10.3847/2041-8205/827/1/L11

  6. Ages of young stars

    CERN Document Server

    Soderblom, David R; Jeffries, Rob D; Mamajek, Eric E; Naylor, Tim

    2013-01-01

    Determining the sequence of events in the formation of stars and planetary systems and their time-scales is essential for understanding those processes, yet establishing ages is fundamentally difficult because we lack direct indicators. In this review we discuss the age challenge for young stars, specifically those less than ~100 Myr old. Most age determination methods that we discuss are primarily applicable to groups of stars but can be used to estimate the age of individual objects. A reliable age scale is established above 20 Myr from measurement of the Lithium Depletion Boundary (LDB) in young clusters, and consistency is shown between these ages and those from the upper main sequence and the main sequence turn-off -- if modest core convection and rotation is included in the models of higher-mass stars. Other available methods for age estimation include the kinematics of young groups, placing stars in Hertzsprung-Russell diagrams, pulsations and seismology, surface gravity measurement, rotation and activ...

  7. Gaia and Variable Stars

    CERN Document Server

    Udalski, A; Skowron, D M; Skowron, J; Pietrukowicz, P; Mróz, P; Poleski, R; Szymański, M K; Kozłowski, S; Wyrzykowski, Ł; Ulaczyk, K; Pawlak, M

    2016-01-01

    We present a comparison of the Gaia DR1 samples of pulsating variable stars - Cepheids and RR Lyrae type - with the OGLE Collection of Variable Stars aiming at the characterization of the Gaia mission performance in the stellar variability domain. Out of 575 Cepheids and 2322 RR Lyrae candidates from the Gaia DR1 samples located in the OGLE footprint in the sky, 559 Cepheids and 2302 RR Lyrae stars are genuine pulsators of these types. The number of misclassified stars is low indicating reliable performance of the Gaia data pipeline. The completeness of the Gaia DR1 samples of Cepheids and RR Lyrae stars is at the level of 60-75% as compared to the OGLE Collection dataset. This level of completeness is moderate and may limit the applicability of the Gaia data in many projects.

  8. Revised Anatomy of Stars

    CERN Document Server

    Dubin, M; Dubin, Maurice; Soberman, Robert K.

    1997-01-01

    Stars accrete near invisible hydrogen dominated agglomerates. This population, the `dark matter,' effects the nature of stars. Measurements show plasma streams impacting Earth, planets, Sun and stars. This mass-energy source contradicts nebula collapse model for stars. The visual derived model, to which later discoveries (e.g., fusion) were appended, is confounded and contradicted by new observations. Discovery of a quantity of beryllium 7 (53 day half-life) in the Earth's upper atmosphere, fusion produced, hence from the solar outer zone, proves core fusion wrong. Magnetically pinched plasmas from aggregates impact stars at hundreds of km/s, create impulsive conditions for nuclear explosions below the surface. Disks with planets aid cluster capture. Planets modulate the influx varying fusion, hence luminosity (e.g., solar cycle). This population, with no assumptions or ad hoc physics, explains mysterious phenomena, e.g., luminosity/wind variation, sunspots, high temperature corona, CMEs, etc. Standard explan...

  9. Mira Symbiotic Stars

    Institute of Scientific and Technical Information of China (English)

    Guo-Liang Lü; Chun-Hua Zhu; Zhan-Wen Han

    2007-01-01

    We have carried out a detailed study of Mira symbiotic stars by means of a population synthesis code. We estimate the number of Mira symbiotic stars in the Galaxy as 1700 - 3100 and the Galactic occurrence rate of Mira symbiotic novae as from ~ 0.9 to 6.0 yr-1,depending on the model assumptions. The distributions of the orbital periods, the masses of the components, mass-loss rates of cool components, mass-accretion rates of hot components and Mira pulsation periods in Mira symbiotic stars are simulated. By a comparison of the number ratio of Mira symbiotic stars to all symbiotic stars, we find the model with the stellar wind model of Winters et al. to be reasonable.

  10. The Carbon Star Phenomenon

    Science.gov (United States)

    Wing, Robert F.

    2000-06-01

    The atmospheres of many stars have chemical compositions that are significantly different from that of the interstellar medium from which they are formed. This symposium considered all kinds of late-type stars showing altered compositions, the carbon stars being simply the best-known of these. All stages of stellar evolution from the main sequence to the ejection of a planetary nebula were considered, with emphasis on the changes that occur on the asymptotic giant branch. The spectroscopic properties of the photospheres and circumstellar envelopes of chemically-peculiar red giant stars, their origins via single-star evolution or mass transfer in binary systems, and the methods currently used to study them were all discussed in detail. This volume includes the full texts of papers given orally at the symposium and abstracts of the posters. Link: http://www.wkap.nl/book.htm/0-7923-6347-7

  11. Neutron Stars and Pulsars

    CERN Document Server

    Becker, Werner

    2009-01-01

    Neutron stars are the most compact astronomical objects in the universe which are accessible by direct observation. Studying neutron stars means studying physics in regimes unattainable in any terrestrial laboratory. Understanding their observed complex phenomena requires a wide range of scientific disciplines, including the nuclear and condensed matter physics of very dense matter in neutron star interiors, plasma physics and quantum electrodynamics of magnetospheres, and the relativistic magneto-hydrodynamics of electron-positron pulsar winds interacting with some ambient medium. Not to mention the test bed neutron stars provide for general relativity theories, and their importance as potential sources of gravitational waves. It is this variety of disciplines which, among others, makes neutron star research so fascinating, not only for those who have been working in the field for many years but also for students and young scientists. The aim of this book is to serve as a reference work which not only review...

  12. Monte Carlo simulation of star/linear and star/star blends with chemically identical monomers

    Energy Technology Data Exchange (ETDEWEB)

    Theodorakis, P E [Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina (Greece); Avgeropoulos, A [Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina (Greece); Freire, J J [Departamento de Ciencias y Tecnicas FisicoquImicas, Universidad Nacional de Educacion a Distancia, Facultad de Ciencias, Senda del Rey 9, 28040 Madrid (Spain); Kosmas, M [Department of Chemistry, University of Ioannina, 45110 Ioannina (Greece); Vlahos, C [Department of Chemistry, University of Ioannina, 45110 Ioannina (Greece)

    2007-11-21

    The effects of chain size and architectural asymmetry on the miscibility of blends with chemically identical monomers, differing only in their molecular weight and architecture, are studied via Monte Carlo simulation by using the bond fluctuation model. Namely, we consider blends composed of linear/linear, star/linear and star/star chains. We found that linear/linear blends are more miscible than the corresponding star/star mixtures. In star/linear blends, the increase in the volume fraction of the star chains increases the miscibility. For both star/linear and star/star blends, the miscibility decreases with the increase in star functionality. When we increase the molecular weight of linear chains of star/linear mixtures the miscibility decreases. Our findings are compared with recent analytical and experimental results.

  13. Berberine inhibits cyclin D1 expression via suppressed binding of AP-1 transcription factors to CCND1 AP-1 motif

    Institute of Scientific and Technical Information of China (English)

    Ye LUO; Yu HAO; Tai-ping SHI; Wei-wei DENG; Na LI

    2008-01-01

    Aim: To verify the suppressive effect of berberine on the proliferation of the human pulmonary giant cell carcinoma cell line PG and to demonstrate the mecha-nisms behind the antitumoral effects of berberine. Methods: The proliferative effects of PG cells were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide colorimetry. The cell cycle was examined by flow cytometry. The expression level of cyclin D1 was detected by RT-PCR. The activities of the activating protein-1 (AP-1) and NF-κB signaling pathways related to cyclin D1 were examined by luciferase assay. The cytoplasmic level of c-Jun was detected by Western blot analysis. An electrophoretic mobility shift assay was used to examiae the binding of transcription factors to the cyclin D1 gene (CCNDl) AP-1 motif. Results: The results showed that the proliferation of PG cells treated with different concentrations (10, 20, and 40 μg/mL) of berberine for 24 and 48 h was suppressed significantly compared to the control group. After treatment with berberine, the proportion of PG cells at the G0/G1 phase increased, while cells at the S and G2/M phases decreased. Berberine could inhibit the expression of cyclin D1 in PG cells. Berberine inhibited the activity of the AP-1 signaling pathway, but had no significant effect on the NF-κB signaling pathway. Berberine suppressed the expression of c-Jun and decreased the binding of tran-scription factors to the CCND1 AP-1 motif. Conclusion: Berberine suppresses the activity of the AP-1 signaling pathway and decreases the binding of transcrip-tion factors to the CCND1 AP-1 motif. This is one of the important mechanisms behind the antitumoral effects of berberine as a regulator of cyclin D1.

  14. Simultaneous beta and gamma spectroscopy

    Science.gov (United States)

    Farsoni, Abdollah T.; Hamby, David M.

    2010-03-23

    A phoswich radiation detector for simultaneous spectroscopy of beta rays and gamma rays includes three scintillators with different decay time characteristics. Two of the three scintillators are used for beta detection and the third scintillator is used for gamma detection. A pulse induced by an interaction of radiation with the detector is digitally analyzed to classify the type of event as beta, gamma, or unknown. A pulse is classified as a beta event if the pulse originated from just the first scintillator alone or from just the first and the second scintillator. A pulse from just the third scintillator is recorded as gamma event. Other pulses are rejected as unknown events.

  15. Violent Star Formation in NGC 2363: Erratum

    Science.gov (United States)

    Gonzalez-Delgado, Rosa M.; Perez, Enrique; Tenorio-Tagle, Guillermo; Vilchez, Jose M.; Terlevich, Elena; Terlevich, Roberto; Telles, Eduardo; Rodríguez Espinosa, Jose M.; Mas-Hesse, Miguel; Garcia-Vargas, Maria Luisa; Diaz, Angeles I.; Cepa, Jordi; Castaneda, Hector

    1996-12-01

    In the paper "Violent Star Formation in NGC 2363" by Rosa M. Gonzalez- Delgado, Enrique Perez, Guillermo Tenorio-Tagle, Jose M. Vilchez, Elena Terlevich, Roberto Terlevich, Eduardo Telles, Jose M. Rodriguez-Espinosa, Miguel Mas-Hesse, Maria Luisa Garcia-Vargas, Angeles I. Diaz, Jordi Cepa, and Hector Castaneda (ApJ, 437,239 [1994)), there are three errors in Section 5.4. The Paschen discontinuity in knot A is (0.82 +/- 0.19) x 10^-16^ ergs s^-1^ cm^-2^ A^-1^, the coefficient in the formula in page 258 is 2.445 x 10^11^, and the units in the ordinate axis of Figure 16 are 10^-15^ ergs cm^-2^ s^-1^ A^-1^. These are typographical errors, and they do not affect the determination of the electron temperature using the Paschen jump and the discussion and conclusions in this paper.

  16. Integrating Particulate Representations into AP Chemistry and Introductory Chemistry Courses

    Science.gov (United States)

    Prilliman, Stephen G.

    2014-01-01

    The College Board's recently revised curriculum for advanced placement (AP) chemistry places a strong emphasis on conceptual understanding, including representations of particle phenomena. This change in emphasis is informed by years of research showing that students could perform algorithmic calculations but not explain those calculations…

  17. Penetration dynamics of AP8 in thin ceramic tiles

    NARCIS (Netherlands)

    Abadjieva, E.; Khoe, Y.S.

    2013-01-01

    The interaction of thin ceramic tiles with AP8 (WC core, 7,62 mm) at 1000 m/s velocity has been studied experimentally and numerically. “Thin” ceramic tiles refers here to ratio of the tile thickness (t) to the projectile diameter, (d), t/d@ 1, as they are both in the same order. The method applied

  18. Research on CoAP%CoAP协议研究

    Institute of Scientific and Technical Information of China (English)

    刘紫青; 程燕; 关联; 桑梓勤; 郝俊瑞

    2013-01-01

    For some M2M applications, there exists problems of constrained networks and nodes, and the HTTP isn't applicable. The Constrained Application Protocol (CoAP) is described and analyzed in this paper, and the mapping between CoAP and HTTP is also included. Then, the comparison of the two protocols is researched. Finally, it can be concluded that CoAP is simple and its overhead is very low, which can well meet the application layer' s communications requirements in the constrained environment.%针对某些M2M应用中存在网络和节点资源受限的情况,不适用HTTP,介绍和分析了受限应用协议CoAP(Constrained Application Protocol)的特点及其与HTTP的映射,并将CoAP和HTTP进行对比研究,发现CoAP简单、开销小,能很好地满足资源受限环境的应用层通信需求.

  19. Beta section Beta: biogeographical patterns of variation and taxonomy.

    NARCIS (Netherlands)

    Letschert, J.P.W.

    1993-01-01

    In Chapter 1 an account is given of the historical subdivision of the genus Beta and its sections, and the relations of the sections are discussed. Emphasis is given to the taxonomic treatment of wild section Beta by various authors. The Linnaean names B. vulgaris L. and B. maritima L. are lectotypi

  20. Catch a Star!

    Science.gov (United States)

    2006-11-01

    ESO and the European Association for Astronomy Education are launching today the 2007 edition of 'Catch a Star!', their international astronomy competition for school students. Now in its fifth year, the competition offers students the chance to win a once-in-a-lifetime trip to ESO's flagship observatory in Chile, as well as many other prizes. Students are invited to 'become astronomers' and embark on a journey to explore the Universe. ESO PR Photo 42/06 The competition includes separate categories - 'Catch a Star Researchers' and 'Catch a Star Adventurers' - to ensure that every student, whatever their level, has the chance to enter and win exciting prizes. For the artistically minded, 'Catch a Star!' also includes an artwork competition, 'Catch a Star Artists'. "'Catch a Star!' offers a unique opportunity for students to learn more about astronomy and about the methods scientists use to discover new things about the Universe", said Douglas Pierce-Price, Education Officer at ESO. In teams, students choose an astronomical topic to study and produce an in-depth report. An important part of the project for 'Catch a Star Researchers' is to think about how ESO's telescopes or a telescope of the future can contribute to their investigations of the subject. As well as the top prize - a trip to one of ESO's observatory sites in Chile - visits to observatories in Germany, Austria and Spain, and many other prizes are also available to be won. 'Catch a Star Researchers' winners will be chosen by an international jury, and 'Catch a Star Adventurers' will be awarded further prizes by lottery. Entries for 'Catch a Star Artists' will be displayed on the web and winners chosen with the help of a public online vote. The first editions of 'Catch a Star!' have attracted several hundred entries from more than 25 countries worldwide. Previous winning entries have included "Star clusters and the structure of the Milky Way" (Budapest, Hungary), "Vega" (Acqui Terme, Italy) and "Venus

  1. The Inflammation-Related Gene S100A12 Is Positively Regulated by C/EBPβ and AP-1 in Pigs

    Directory of Open Access Journals (Sweden)

    Xinyun Li

    2014-08-01

    Full Text Available S100A12 is involved in the inflammatory response and is considered an important marker for many inflammatory diseases in humans. Our previous studies indicated that the S100A12 gene was abundant in the immune tissues of pigs and was significantly upregulated during infection with Haemophilus parasuis (HPS or porcine circovirus type 2 (PCV2. In this study, the mechanism of transcriptional regulation of S100A12 was investigated in pigs. Our results showed that S100A12, CCAAT/enhancer-binding protein beta (C/EBPβ and activator protein-1 (AP-1 genes were up-regulated in PK-15 (ATCC, CCL-33 cells when treated with LPS or Poly I: C. Additionally, the promoter activity and expression level of the S100A12 gene were significantly upregulated when C/EBPβ or AP-1 were overexpressed. We utilized electromobility shift assays (EMSA to confirm that C/EBPβ and AP-1 could directly bind the S100A12 gene promoter. We also found that the transcriptional activity and expression levels of C/EBPβ and AP-1 could positively regulate each other. Furthermore, the promoter activity of the S100A12 gene was higher when C/EBPβ and AP-1 were cotransfected than when they were transfected individually. We concluded that the S100A12 gene was cooperatively and positively regulated by C/EBPβ and AP-1 in pigs. Our study offers new insight into the transcriptional regulation of the S100A12 gene.

  2. The inflammation-related gene S100A12 is positively regulated by C/EBPβ and AP-1 in pigs.

    Science.gov (United States)

    Li, Xinyun; Tang, Juan; Xu, Jing; Zhu, Mengjin; Cao, Jianhua; Liu, Ying; Yu, Mei; Zhao, Shuhong

    2014-08-08

    S100A12 is involved in the inflammatory response and is considered an important marker for many inflammatory diseases in humans. Our previous studies indicated that the S100A12 gene was abundant in the immune tissues of pigs and was significantly upregulated during infection with Haemophilus parasuis (HPS) or porcine circovirus type 2 (PCV2). In this study, the mechanism of transcriptional regulation of S100A12 was investigated in pigs. Our results showed that S100A12, CCAAT/enhancer-binding protein beta (C/EBPβ) and activator protein-1 (AP-1) genes were up-regulated in PK-15 (ATCC, CCL-33) cells when treated with LPS or Poly I: C. Additionally, the promoter activity and expression level of the S100A12 gene were significantly upregulated when C/EBPβ or AP-1 were overexpressed. We utilized electromobility shift assays (EMSA) to confirm that C/EBPβ and AP-1 could directly bind the S100A12 gene promoter. We also found that the transcriptional activity and expression levels of C/EBPβ and AP-1 could positively regulate each other. Furthermore, the promoter activity of the S100A12 gene was higher when C/EBPβ and AP-1 were cotransfected than when they were transfected individually. We concluded that the S100A12 gene was cooperatively and positively regulated by C/EBPβ and AP-1 in pigs. Our study offers new insight into the transcriptional regulation of the S100A12 gene.

  3. Cyclic modular beta-sheets.

    Science.gov (United States)

    Woods, R Jeremy; Brower, Justin O; Castellanos, Elena; Hashemzadeh, Mehrnoosh; Khakshoor, Omid; Russu, Wade A; Nowick, James S

    2007-03-07

    The development of peptide beta-hairpins is problematic, because folding depends on the amino acid sequence and changes to the sequence can significantly decrease folding. Robust beta-hairpins that can tolerate such changes are attractive tools for studying interactions involving protein beta-sheets and developing inhibitors of these interactions. This paper introduces a new class of peptide models of protein beta-sheets that addresses the problem of separating folding from the sequence. These model beta-sheets are macrocyclic peptides that fold in water to present a pentapeptide beta-strand along one edge; the other edge contains the tripeptide beta-strand mimic Hao [JACS 2000, 122, 7654] and two additional amino acids. The pentapeptide and Hao-containing peptide strands are connected by two delta-linked ornithine (deltaOrn) turns [JACS 2003, 125, 876]. Each deltaOrn turn contains a free alpha-amino group that permits the linking of individual modules to form divalent beta-sheets. These "cyclic modular beta-sheets" are synthesized by standard solid-phase peptide synthesis of a linear precursor followed by solution-phase cyclization. Eight cyclic modular beta-sheets 1a-1h containing sequences based on beta-amyloid and macrophage inflammatory protein 2 were synthesized and characterized by 1H NMR. Linked cyclic modular beta-sheet 2, which contains two modules of 1b, was also synthesized and characterized. 1H NMR studies show downfield alpha-proton chemical shifts, deltaOrn delta-proton magnetic anisotropy, and NOE cross-peaks that establish all compounds but 1c and 1g to be moderately or well folded into a conformation that resembles a beta-sheet. Pulsed-field gradient NMR diffusion experiments show little or no self-association at low (

  4. The nature of the F str lambda 4077 stars. 3: Spectroscopy of the barium dwarfs and other CP stars

    Science.gov (United States)

    North, P.; Berthet, S.; Lanz, T.

    1994-01-01

    The abundances of C, O, Al, Ca, iron-peak and s-process elements have been derived from high-resolution spectra for a sample of stars classified as F str lambda 4077 by Bidelman. Among the 20 stars mentioned by Bidelman, we have discovered 8 barium dwarfs (or CH subgiants, according to Bond's terminology), while a 9th star, HD 182274, was already known as a CH subgiant. In addition, we have analyzed three barium stars taken from the list of Lu et al. (1983) which are probably dwarfs rather than giants, and three CH subgiants. The other 11 F str lambda 4077 stars resemble either the delta Delphini stars, since their iron abundance is enhanced while Ca is normal, or are probably spectrum composites. A few Am, Ap, lambda Bootis and normal stars have been analyzed for comparison. In particular, we have included three lambda Boo candidates, selected from their photometric properties, and their iron deficiency is confirmed. The spectroscopic, photometric and statistical evidences concerning the Ba dwarfs, support the idea that these stars may be the main sequence counterparts, and possibly the progenitors of the Ba giants. The C/O ratio varies in these stars from normal values to a maximum of 1.5, but mostly within 0.6 and 1.2. Some of these objects may therefore be considered, in this sense, as carbon stars. On the other hand, the abundances of carbon and s-process elements relative to iron are inversely correlated with metallicity, and may even exceed significantly those of typical, solar-metallicity carbon stars. Metal-deficient C stars must therefore have (C/Fe) greater than or approximately equal to 1 and (s/Fe) greater than or approximately equal to 1.5 as soon as (Fe/H) less than or approximately equal to -1. The neutron exposure is shown to increase when the metallicity decreases, which is compatible with the C-13 (alpha, n) O-16 neutron source, but not with the Ne-22 (alpha, n) Mg-25 one. The evolutionary state (within the main sequence) of the Ba dwarfs, is

  5. Hot Subluminous Stars

    Science.gov (United States)

    Heber, U.

    2016-08-01

    Hot subluminous stars of spectral type B and O are core helium-burning stars at the blue end of the horizontal branch or have evolved even beyond that stage. Most hot subdwarf stars are chemically highly peculiar and provide a laboratory to study diffusion processes that cause these anomalies. The most obvious anomaly lies with helium, which may be a trace element in the atmosphere of some stars (sdB, sdO) while it may be the dominant species in others (He-sdB, He-sdO). Strikingly, the distribution in the Hertzsprung-Russell diagram of He-rich versus He-poor hot subdwarf stars of the globular clusters ω Cen and NGC 2808 differ from that of their field counterparts. The metal-abundance patterns of hot subdwarfs are typically characterized by strong deficiencies of some lighter elements as well as large enrichments of heavy elements. A large fraction of sdB stars are found in close binaries with white dwarf or very low-mass main sequence companions, which must have gone through a common-envelope (CE) phase of evolution. Because the binaries are detached they provide a clean-cut laboratory to study this important but yet poorly understood phase of stellar evolution. Hot subdwarf binaries with sufficiently massive white dwarf companions are viable candidate progenitors of type Ia supernovae both in the double degenerate as well as in the single degenerate scenario as helium donors for double detonation supernovae. The hyper-velocity He-sdO star US 708 may be the surviving donor of such a double detonation supernova. Substellar companions to sdB stars have also been found. For HW Vir systems the companion mass distribution extends from the stellar into the brown dwarf regime. A giant planet to the acoustic-mode pulsator V391 Peg was the first discovery of a planet that survived the red giant evolution of its host star. Evidence for Earth-size planets to two pulsating sdB stars have been reported and circumbinary giant planets or brown dwarfs have been found around HW

  6. Inorganic, radioisotopic and organic analysis of 241-AP-101 tank waste

    Energy Technology Data Exchange (ETDEWEB)

    SK Fiskum; PR Bredt; JA Campbell; LR Greenwood; OT Farmer; GJ Lumetta; GM Mong; RT Ratner; CZ Soderquist; RG Swoboda; MW Urie; JJ Wagner

    2000-06-28

    Battelle received five samples from Hanford waste tank 241-AP-101, taken at five different depths within the tank. No visible solids or organic layer were observed in the individual samples. Individual sample densities were measured, then the five samples were mixed together to provide a single composite. The composite was homogenized and representative sub-samples taken for inorganic, radioisotopic, and organic analysis. All analyses were performed on triplicate sub-samples of the composite material. The sample composite did not contain visible solids or an organic layer. A subsample held at 10 C for seven days formed no visible solids. The characterization of the 241-AP-101 composite samples included: (1) Inductively-coupled plasma spectrometry for Ag, Al, Ba, Bi, Ca, Cd, Cr, Cu, Fe, K, La, Mg, Mn, Na, Nd, Ni, P, Pb, Pd, Ru, Rh, Si, Sr, Ti, U, Zn, and Zr (Note: Although not specified in the test plan, As, B, Be, Co, Li, Mo, Sb, Se, Sn, Tl, V, W, and Y were also measured and reported for information only) (2) Radioisotopic analyses for total alpha and total beta activities, {sup 3}H, {sup 14}C, {sup 60}Co, {sup 79}Se, {sup 90}Sr, {sup 99}Tc as pertechnetate, {sup 106}Ru/Rh, {sup 125}Sb, {sup 134}Cs, {sup 137}Cs, {sup 152}Eu, {sup 154}Eu, {sup 155}Eu, {sup 238}Pu, {sup 239+240}Pu, {sup 241}Am, {sup 242}Cm, and {sup 243+244}Cm; (3) Inductively-coupled plasma mass spectrometry for {sup 237}Np, {sup 239}Pu, {sup 240}Pu, {sup 99}Tc, {sup 126}Sn, {sup 129}I, {sup 231}Pa, {sup 233}U, {sup 234}U, {sup 235}U, {sup 236}U, {sup 238}U, {sup 241}AMU, {sup 242}AMU, {sup 243}AMU, As, B, Be, Ce, Co, Cs, Eu, I, Li, Mo, Pr, Rb, Sb, Se, Ta, Te, Th, Tl, V, and W; (4) total U by kinetic phosphorescence analysis; (5) Ion chromatography for Cl, F, NO{sub 2}, NO{sub 3}, PO{sub 4}, SO{sub 4}, acetate, formate, oxalate, and citrate; (6) Density, inorganic carbon and organic carbon by two different methods, mercury, free hydroxide, ammonia, and cyanide. The 241-AP-101 composite met all

  7. Dense Axion Stars

    CERN Document Server

    Braaten, Eric; Zhang, Hong

    2015-01-01

    If the dark matter consists of axions, gravity can cause them to coalesce into axion stars, which are stable gravitationally bound Bose-Einstein condensates of axions. In the previously known axion stars, gravity and the attractive force between pairs of axions are balanced by the kinetic pressure.If the axion mass energy is $mc^2= 10^{-4}$ eV, these dilute axion stars have a maximum mass of about $10^{-14} M_\\odot$. We point out that there are also dense axion stars in which gravity is balanced by the mean-field pressure of the axion condensate. We study axion stars using the leading term in a systematically improvable approximation to the effective potential of the nonrelativistic effective field theory for axions. Using the Thomas-Fermi approximation in which the kinetic pressure is neglected, we find a sequence of new branches of axion stars in which gravity is balanced by the mean-field interaction energy of the axion condensate. If $mc^2 = 10^{-4}$ eV, the first branch of these dense axion stars has mas...

  8. Dense Axion Stars

    Science.gov (United States)

    Braaten, Eric; Mohapatra, Abhishek; Zhang, Hong

    2016-09-01

    If the dark matter particles are axions, gravity can cause them to coalesce into axion stars, which are stable gravitationally bound systems of axions. In the previously known solutions for axion stars, gravity and the attractive force between pairs of axions are balanced by the kinetic pressure. The mass of these dilute axion stars cannot exceed a critical mass, which is about 10-14M⊙ if the axion mass is 10-4 eV . We study axion stars using a simple approximation to the effective potential of the nonrelativistic effective field theory for axions. We find a new branch of dense axion stars in which gravity is balanced by the mean-field pressure of the axion Bose-Einstein condensate. The mass on this branch ranges from about 10-20M⊙ to about M⊙ . If a dilute axion star with the critical mass accretes additional axions and collapses, it could produce a bosenova, leaving a dense axion star as the remnant.

  9. Dense Axion Stars

    Science.gov (United States)

    Mohapatra, Abhishek; Braaten, Eric; Zhang, Hong

    2016-03-01

    If the dark matter consists of axions, gravity can cause them to coalesce into axion stars, which are stable gravitationally bound Bose-Einstein condensates of axions. In the previously known axion stars, gravity and the attractive force between pairs of axions are balanced by the kinetic pressure. If the axion mass energy is mc2 =10-4 eV, these dilute axion stars have a maximum mass of about 10-14M⊙ . We point out that there are also dense axion stars in which gravity is balanced by the mean-field pressure of the axion condensate. We study axion stars using the leading term in a systematically improvable approximation to the effective potential of the nonrelativistic effective field theory for axions. Using the Thomas-Fermi approximation in which the kinetic pressure is neglected, we find a sequence of new branches of axion stars in which gravity is balanced by the mean-field interaction energy of the axion condensate. If mc2 =10-4 4 eV, the first branch of these dense axion stars has mass ranging from about 10-11M⊙ toabout M⊙.

  10. Cooling of Neutron Stars

    Directory of Open Access Journals (Sweden)

    Grigorian H.

    2010-10-01

    Full Text Available We introduce the theoretical basis for modeling the cooling evolution of compact stars starting from Boltzmann equations in curved space-time. We open a discussion on observational verification of different neutron star models by consistent statistics. Particular interest has the question of existence of quark matter deep inside of compact object, which has to have a specific influence on the cooling history of the star. Besides of consideration of several constraints and features of cooling evolution, which are susceptible of being critical for internal structure of hot compact stars we have introduced a method of extraction of the mass distribution of the neutron stars from temperature and age data. The resulting mass distribution has been compared with the one suggested by supernove simulations. This method can be considered as an additional checking tool for the consistency of theoretical modeling of neutron stars. We conclude that the cooling data allowed existence of neutron stars with quark cores even with one-flavor quark matter.

  11. SPECTROPOLARIMETRY OF THE CLASSICAL T TAURI STAR BP TAU

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Wei; Johns-Krull, Christopher M., E-mail: wc2@rice.edu, E-mail: cmj@rice.edu [Department of Physics and Astronomy, Rice University, Houston, TX 77005 (United States)

    2013-10-20

    We implement a least-squares deconvolution (LSD) code to study magnetic fields on cool stars. We first apply our code to high-resolution optical echelle spectra of 53 Cam (a magnetic Ap star) and three well-studied cool stars (Arcturus, 61 Cyg A, and ξ Boo A) as well as the Sun (by observing the asteroid Vesta) as tests of the code and the instrumentation. Our analysis is based on several hundred photospheric lines spanning the wavelength range 5000 Å to 9000 Å. We then apply our LSD code to six nights of data on the Classical T Tauri Star BP Tau. A maximum longitudinal field of 370 ± 80 G is detected from the photospheric lines on BP Tau. A 1.8 kG dipole tilted at 129° with respect to the rotation axis and a 1.4 kG octupole tilted at 104° with respect to the rotation axis, both with a filling factor of 0.25, best fit our LSD Stokes V profiles. Measurements of several emission lines (He I 5876 Å, Ca II 8498 Å, and 8542 Å) show the presence of strong magnetic fields in the line formation regions of these lines, which are believed to be the base of the accretion footpoints. The field strength measured from these lines shows night-to-night variability consistent with rotation of the star.

  12. The search for magnetic fields in mercury-manganese stars

    CERN Document Server

    Makaganiuk, V; Piskunov, N; Jeffers, S V; Johns-Krull, C M; Keller, C U; Rodenhuis, M; Snik, F; Stempels, H C; Valenti, J A

    2010-01-01

    We performed a highly sensitive search for magnetic fields on a large set of HgMn stars. With the aid of a new polarimeter attached to the HARPS spectrometer at the ESO 3.6m-telescope, we obtained high-quality circular polarization spectra of 41 single and double HgMn stars. Using a multi-line analysis technique on each star, we co-added information from hundreds of spectral lines resulting in significantly greater sensitivity to the presence of magnetic fields, including very weak fields. For the 47 individual objects studied, including 6 components of SB2 systems, we do not detect any magnetic fields at greater than the 3 sigma level. The lack of detection in the circular polarization profiles indicates that if strong fields are present on these stars, they must have complex surface topologies. For simple global fields, our detection limits imply upper limits to the fields present of 2-10 Gauss in the best cases. We conclude that HgMn stars lack large-scale magnetic fields, typical for spotted magnetic Ap s...

  13. Relativistic Stars in Beyond Horndeski Theories

    CERN Document Server

    Babichev, Eugeny; Langlois, David; Saito, Ryo; Sakstein, Jeremy

    2016-01-01

    This work studies relativistic stars in beyond Horndeski scalar-tensor theories that exhibit a breaking of the Vainshtein mechanism inside matter, focusing on a model based on the quartic beyond Horndeski Lagrangian. We self-consistently derive the scalar field profile for static spherically symmetric objects in asymptotically de Sitter space-time and show that the Vainshtein breaking branch of the solutions is the physical branch thereby resolving several ambiguities with non-relativistic frameworks. The geometry outside the star is shown to be exactly Schwarzschild-de Sitter and therefore the PPN parameter $\\beta_{\\rm PPN}=1$, confirming that the external screening works at the post-Newtonian level. The Tolman-Oppenheimer-Volkoff (TOV) equations are derived and a new lower bound on the Vainshtein breaking parameter $\\Upsilon_1>-4/9$ is found by requiring the existence of static spherically symmetric stars. Focusing on the unconstrained case where $\\Upsilon_1<0$, we numerically solve the TOV equations for...

  14. The Polaris Project / NorthStar implementation

    Science.gov (United States)

    Willson, L. A.; Bennett, D. H.; Engelhaupt, T.

    2001-12-01

    The advent of the World Wide Web opens new opportunities for education; it also changes the environment within which we teach. As Marshall McLuhan said many years ago: "The medium is the message". What kind of medium is the Web, and how is it best harnessed for use in astronomy education? We are developing a sequence of one-credit web-based courses covering basic astronomical topics as a means of exploring what the web can and cannot do. Our first course, NorthStar, deals with coordinates, sky motions, and navigation by the stars. It has been through "beta testing" and is being offered as an experimental course for spring. Our second course, EveningStar, is under development. The course materials are open and may be used as a supplement to any course, or for independent study; the homework, discussion group, and other human-intervention features require a student to register for the course. We invite people to make use of our open materials and, in exchange, to provide us with feedback about how well it works. We acknowledge support for this project from NASA (NAG 58465) and the Department of Physics and Astronomy, Iowa State University.

  15. Symbiotic Stars in X-rays

    Science.gov (United States)

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

    2014-01-01

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

  16. Quark matter nucleation in neutron stars and astrophysical implications

    CERN Document Server

    Bombaci, Ignazio; Vidana, Isaac; Providencia, Constanca

    2016-01-01

    A phase of strong interacting matter with deconfined quarks is expected in the core of massive neutron stars. We investigate the quark deconfinement phase transition in cold (T = 0) and hot beta-stable hadronic matter. Assuming a first order phase transition, we calculate and compare the nucleation rate and the nucleation time due to quantum and thermal nucleation mechanisms. We show that above a threshold value of the central pressure a pure hadronic star (HS) (i.e. a compact star with no fraction of deconfined quark matter) is metastable to the conversion to a quark star (QS) (i.e. a hybrid star or a strange star). This process liberates an enormous amount of energy, of the order of 10^{53}~erg, which causes a powerful neutrino burst, likely accompanied by intense gravitational waves emission, and possibly by a second delayed (with respect to the supernova explosion forming the HS) explosion which could be the energy source of a powerful gamma-ray burst (GRB). This stellar conversion process populates the Q...

  17. Wind Circulation in Selected Rotating Magnetic Early-B Stars

    CERN Document Server

    Smith, M A; Smith, Myron A.; Groote, Detlef

    2001-01-01

    The rotating magnetic B stars have oblique dipolar magnetic fields and often anomalous helium and metallic compositions. These stars develop co-rotating torus-shaped clouds by channelling winds from their magnetic poles to an anchored planar disk over the magnetic equator. The line absorptions from the cloud can be studied as the complex rotates and periodically occults the star. We describe an analysis of the clouds of four stars (HD184927, beta Cep, sigma Ori E, and HR6684). From line synthesis models, we find that the metallic compositions are spatially uniform over the stars' surfaces. Next, using the Hubeny CIRCUS code, we demonstate that periodic UV continuum fluxes can be explained by the absorption of low-excitation lines. The analysis also quantifies the cloud temperatures, densities, and turbulences, which appear to increase inward toward the stars. The temperatures range from about 12,000K for the weak Fe lines up to temperatures of 33,000K for N V absorptions, which is in excess of temperatures ex...

  18. A Novel Approach for Star Extraction from Star Image

    Institute of Scientific and Technical Information of China (English)

    ZHENGSheng; LIUJian; TIANJinwen; YANGRuijuan

    2005-01-01

    Star acquisition is one of the most timeconsuming routines in star tracker operation. One star Point spread function (PSF) forms a near Gaussian distribution in the star image, the star image can be regarded as 2-D intensity surface, and every pixel is the sampled point. The star cluster grouping is to find the highes tintensity pixel among the PSFs and collect the adjacent pixels and group them. The possible highest intensity pixels are the maximum extremum points of the 2-D intensity surface. To efficiently extract star from the star image, a novel star acquisition approach, which uses the simplified least squares support vector machines regression algorithm to find the optimal intensity surface function and predictthe maximum extremum points, is proposed. Comput erexperiments are carried out for the simulated star images.The experimental results demonstrate that the proposed method has a lot of advantages, including the high efficiency and good robustness over a wide range of sensor noise.

  19. Infrared spectroscopy of stars

    Science.gov (United States)

    Merrill, K. M.; Ridgway, S. T.

    1979-01-01

    This paper reviews applications of IR techniques in stellar classification, studies of stellar photospheres, elemental and isotopic abundances, and the nature of remnant and ejected matter in near-circumstellar regions. Qualitative IR spectral classification of cool and hot stars is discussed, along with IR spectra of peculiar composite star systems and of obscured stars, and IR characteristics of stellar populations. The use of IR spectroscopy in theoretical modeling of stellar atmospheres is examined, IR indicators of stellar atmospheric composition are described, and contributions of IR spectroscopy to the study of stellar recycling of interstellar matter are summarized. The future of IR astronomy is also considered.

  20. Nuclear physics of stars

    CERN Document Server

    Iliadis, Christian

    2007-01-01

    Thermonuclear reactions in stars is a major topic in the field of nuclear astrophysics, and deals with the topics of how precisely stars generate their energy through nuclear reactions, and how these nuclear reactions create the elements the stars, planets and - ultimately - we humans consist of. The present book treats these topics in detail. It also presents the nuclear reaction and structure theory, thermonuclear reaction rate formalism and stellar nucleosynthesis. The topics are discussed in a coherent way, enabling the reader to grasp their interconnections intuitively. The book serves bo

  1. Entropy Production of Stars

    Directory of Open Access Journals (Sweden)

    Leonid M. Martyushev

    2015-06-01

    Full Text Available The entropy production (inside the volume bounded by a photosphere of main-sequence stars, subgiants, giants, and supergiants is calculated based on B–V photometry data. A non-linear inverse relationship of thermodynamic fluxes and forces as well as an almost constant specific (per volume entropy production of main-sequence stars (for 95% of stars, this quantity lies within 0.5 to 2.2 of the corresponding solar magnitude is found. The obtained results are discussed from the perspective of known extreme principles related to entropy production.

  2. Estrogen receptor alpha, fos-related antigen-2, and c-Jun coordinately regulate human UDP glucuronosyltransferase 2B15 and 2B17 expression in response to 17beta-estradiol in MCF-7 cells.

    Science.gov (United States)

    Hu, Dong Gui; Mackenzie, Peter I

    2009-08-01

    UDP-glucuronosyltransferase 2B15 and 2B17 expression is up-regulated by 17beta-estradiol in MCF-7 breast cancer cells, as assessed by quantitative real-time polymerase chain reaction. Using 5'-deletion mapping and site-directed mutagenesis, we demonstrate that 17beta-estradiol activation of UGT2B15 gene transcription is mediated by a 282-base pair fragment positioned -454 to -172 nucleotides from the translation start site. This region contains two putative activator protein-1 (AP-1) elements, one imperfect estrogen response element (ERE), and two consensus ERE half-sites. We propose that these five sites act as an estrogen response unit (ERU), because mutation in any site reduces activation of the UGT2B15 promoter by 17beta-estradiol. Despite the presence of two AP-1 elements, the UGT2B15 promoter is not responsive to the AP-1 activator phorbol 12-myristate 13-acetate. Although electrophoretic mobility shift assays (EMSA) indicate that the AP-1 proteins c-Jun and Fos-related antigen 2 (Fra-2) bound to the distal AP-1 site, binding of Jun or Fos family members to the proximal AP-1 site was not detected by EMSA. Chromatin immunoprecipitation assays showed a 17beta-estradiol-induced recruitment of estrogen receptor (ER) alpha, c-Jun, and Fra-2 to the 282-bp ERU. The involvement of these three transcription factors in the stimulation of UGT2B15 gene expression by 17beta-estradiol was confirmed by siRNA silencing experiments. Mutagenesis and siRNA experiments indicate that UGT2B17 expression is also regulated by 17beta-estradiol via the ERU, which is fully conserved in both promoters. Because UGT2B15 and UGT2B17 inactivate steroid hormones by glucuronidation, the regulation of their genes by 17beta-estradiol may maintain steroid hormone homeostasis and prevent excessive estrogen signaling activity.

  3. Integration of BETA with Eclipse

    DEFF Research Database (Denmark)

    Andersen, Peter; Madsen, Ole Lehrmann; Enevoldsen, Mads Brøgger

    2004-01-01

    This paper presents language interoperability issues appearing in order to implement support for the BETA language in the Java-based Eclipse integrated development environment. One of the challenges is to implement plug-ins in BETA and be able to load them in Eclipse. In order to do this, some form...

  4. Measurements of sin 2 $\\beta$

    CERN Document Server

    Tricomi, A

    2000-01-01

    A review of the most recent measurements of the CP violating parameter sin 2 beta from LEP and CDF is reported. These yield an average value of sin 2 beta =0.91+or-0.35, giving a confidence level that CP violation in the B system has been observed of almost 99%. (10 refs).

  5. Beta decay of Cu-56

    NARCIS (Netherlands)

    Borcea, R; Aysto, J; Caurier, E; Dendooven, P; Doring, J; Gierlik, M; Gorska, M; Grawe, H; Hellstrom, M; Janas, Z; Jokinen, A; Karny, M; Kirchner, R; La Commara, M; Langanke, K; Martinez-Pinedo, G; Mayet, P; Nieminen, A; Nowacki, F; Penttila, H; Plochocki, A; Rejmund, M; Roeckl, E; Schlegel, C; Schmidt, K; Schwengner, R; Sawicka, M

    2001-01-01

    The proton-rich isotope Cu-56 was produced at the GSI On-Line Mass Separator by means of the Si-28(S-32, p3n) fusion-evaporation reaction. Its beta -decay properties were studied by detecting beta -delayed gamma rays and protons. A half-Life of 93 +/- 3 ms was determined for Cu-56. Compared to the p

  6. Beta Function and Anomalous Dimensions

    DEFF Research Database (Denmark)

    Pica, Claudio; Sannino, Francesco

    2011-01-01

    We demonstrate that it is possible to determine the coefficients of an all-order beta function linear in the anomalous dimensions using as data the two-loop coefficients together with the first one of the anomalous dimensions which are universal. The beta function allows to determine the anomalou...

  7. RAVEN Beta Release

    Energy Technology Data Exchange (ETDEWEB)

    Rabiti, Cristian [Idaho National Lab. (INL), Idaho Falls, ID (United States); Alfonsi, Andrea [Idaho National Lab. (INL), Idaho Falls, ID (United States); Cogliati, Joshua Joseph [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mandelli, Diego [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kinoshita, Robert Arthur [Idaho National Lab. (INL), Idaho Falls, ID (United States); Wang, Congjian [Idaho National Lab. (INL), Idaho Falls, ID (United States); Maljovec, Daniel Patrick [Idaho National Lab. (INL), Idaho Falls, ID (United States); Talbot, Paul William [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-02-01

    This documents the release of the Risk Analysis Virtual Environment (RAVEN) code. A description of the RAVEN code is provided, and discussion of the release process for the M2LW-16IN0704045 milestone. The RAVEN code is a generic software framework to perform parametric and probabilistic analysis based on the response of complex system codes. RAVEN is capable of investigating the system response as well as the input space using Monte Carlo, Grid, or Latin Hyper Cube sampling schemes, but its strength is focused toward system feature discovery, such as limit surfaces, separating regions of the input space leading to system failure, using dynamic supervised learning techniques. RAVEN has now increased in maturity enough for the Beta 1.0 release.

  8. Utilizing Synthetic Spectra to Refine Lambda Boo Stars' UV Classification Criteria

    Science.gov (United States)

    Cheng, Kwang-Ping; Neff, James E.; Johnson, Dustin; Tarbell, Erik; Romo, Christopher; Steele, Patricia; Gray, Richard O.; Corbally, Christopher J.

    2016-01-01

    Lambda Boo-type stars are a group of late B to early F-type Population I dwarfs that show deficiencies of iron-peak elements (up to 2 dex), but their C, N, O, and S abundances are near solar. This stellar class has recently regained the spotlight because of the directly-imaged planets around a confirmed Lambda Boo star, HR 8799, and a suggested Lambda Boo star Beta Pictoris. The discovery of a giant asteroid belt around Vega, another possible Lambda Boo star, also suggests hidden planets. This possible link between Lambda Boo stars and planet-bearing stars motivates us to study Lambda Boo stars systematically. Since the peculiar nature of the prototype Lambda Bootis was first noticed in 1943, Lambda Boo candidates published in the literature have been selected using widely different criteria. The Lambda Boo label has been applied to almost any peculiar A-type stars that do not fit elsewhere. In order to determine the origin of Lambda Boo stars' unique abundance pattern and to better discriminate between theories explaining the Lambda Boo phenomenon, a consistent working definition of Lambda Boo stars is needed. We have re-evaluated all published Lambda Boo candidates and their available ultraviolet and visible spectra. Using observed and synthetic spectra, we explored the classification of Lambda Boo stars and developed quantitative criteria that discriminate metal-poor stars from bona fide Lambda Boo stars. With model spectra, we demonstrated that the (C I 1657 Angstrom)/ (Al II 1671 Angstrom) line ratio is the best single criterion to distinguish between Lambda Boo stars and metal weak stars, and that one cannot use a single C I/Al II cut-off value as a Lambda Boo classification criterion. The C I/Al II cut-off value is a function of a star's effective temperature and metallicity. Using these stricter Lambda Boo classification criteria, we concluded that neither Beta Pictoris nor Vega should be classified as Lambda Boo stars.

  9. Exocomet signatures around the A-shell star $\\Phi$ Leo?

    CERN Document Server

    Eiroa, C; Montesinos, B; Villaver, E; Absil, O; Henning, Th; Bayo, A; Canovas, H; Carmona, A; Chen, Ch; Ertel, S; Iglesias, D P; Launhardt, R; Maldonado, J; Meeus, G; Moór, A; Mora, A; Mustill, A J; Olofsson, J; Rauw, G; Riviere-Marichalar, P; Roberge, A

    2016-01-01

    We present an intensive monitoring of high-resolution spectra of the Ca {\\sc ii} K line in the A7IV shell star $\\Phi$ Leo at very short (minutes, hours), short (night to night), and medium term (weeks, months) timescales. The spectra show remarkable variable absorptions on timescales of hours, days and months. The characteristics of these sporadic events are very similar to most of the ones observed towards the debris disk host star $\\beta$ Pic, which are usually interpreted as signs of the evaporation of solid, comet-like bodies grazing or falling onto the star. Therefore, our results suggest the presence of solid bodies around $\\Phi$ Leo. To our knowledge, with the exception of $\\beta$ Pic, our monitoring is the one with the best time resolution at the mentioned timescales done on a star with events attributed to exocomets. Assuming the cometary scenario, and considering the timescales of our monitoring, our results point to $\\Phi$ Leo presenting the richest environment with comet-like events yet known, sec...

  10. The relevance of ambipolar diffusion for neutron star evolution

    CERN Document Server

    Passamonti, Andrea; Pons, José A; Miralles, Juan A

    2016-01-01

    We study ambipolar diffusion in strongly magnetised neutron stars, with special focus on the effects of neutrino reaction rates and the impact of a superfluid/superconducting transition in the neutron star core. For axisymmetric magnetic field configurations, we determine the deviation from $\\beta-$equilibrium induced by the magnetic force and calculate the velocity of the slow, quasi-stationary, ambipolar drift. We study the temperature dependence of the velocity pattern and clearly identify the transition to a predominantly solenoidal flow. For stars without superconducting/superfluid constituents and with a mixed poloidal-toroidal magnetic field of typical magnetar strength, we find that ambipolar diffusion proceeds fast enough to have a significant impact on the magnetic field evolution only at low core temperatures, $T \\lesssim 1-2\\times10^8$ K. The ambipolar diffusion timescale becomes appreciably shorter when fast neutrino reactions are present, because the possibility to balance part of the magnetic f...

  11. Physical parameters of three field RR Lyrae stars

    CERN Document Server

    Ferro, A Arellano; Jaimes, R Figuera

    2012-01-01

    Str\\"omgren $uvby-\\beta$ photometry of the stars classified as RR Lyrae stars RU Piscium, SS Piscium and TU Ursae Majoris has been used to estimate their iron abundance, temperature, gravity and absolute magnitude. The stability of the pulsating period is discussed. The nature of SS Psc as a RRc or a HADS is addressed. The reddening of each star is estimated from the Str\\"omgren colour indices and reddening sky maps. The results of three approaches to the determination of [Fe/H], $T_{\\rm eff}$ and $\\log(g)$ are discussed: Fourier light curve decomposition, the Preston $\\Delta S$ index and the theoretical grids on the $(b-y)_o - c_1{_o}$ plane.

  12. Physical parameters of seven field RR Lyrae Stars in Bootes

    CERN Document Server

    Peña, J H; Miller, R Peña; Sareyan, J P; Alvarez, M

    2009-01-01

    Str\\"omgren uvby-beta photometry is reported for the RR Lyrae stars AE, RS, ST, TV, TW, UU, and XX in Bootes. The physical parameters M/Mo, log (L/Lo), M_V, log T_eff and [Fe/H], have been estimated from the Fourier decomposition of the light curves and the empirical calibrations developed for this type of stars. Detailed behavior of the stars along the cycle of pulsation has been determined from the observed photometric indices and the synthetic indices from atmospheric models. The reddening of the zone is found to be negligible, as estimated from the reddening of several objects in the same region of the sky. Hence the distances to the individual objects are also estimated.

  13. Shear viscosity of $\\beta$-stable nuclear matter

    CERN Document Server

    Benhar, Omar

    2009-01-01

    Viscosity plays a critical role in determining the stability of rotating neutron stars. We report the results of a calculation of the shear viscosity of $\\beta$~-~stable matter, carried out using an effective interaction based on a state-of-the-art nucleon-nucleon potential and the formalism of correlated basis functions. Within our approach the equation of state, determining the proton fraction, and the nucleon-nucleon scattering probability are consistently obtained from the same dynamical model. The results show that, while the neutron contribution to the viscosity is always dominant, above nuclear saturation density the electron contribution becomes appreciable.

  14. VizieR Online Data Catalog: PHAT. XVI. Star cluster masses and ages (Johnson+, 2016)

    Science.gov (United States)

    Johnson, L. C.; Seth, A. C.; Dalcanton, J. J.; Beerman, L. C.; Fouesneau, M.; Lewis, A. R.; Weisz, D. R.; Williams, B. F.; Bell, E. F.; Dolphin, A. E.; Larsen, S. S.; Sandstrom, K.; Skillman, E. D.

    2016-11-01

    The Panchromatic Hubble Andromeda Treasury (PHAT) survey imaged 1/3 of the disk of M31 in six passbands spanning near-ultraviolet to near-infrared wavelengths. The survey provides resolved stellar photometry of 117 million sources that we use to determine the properties of both the cluster and field populations, with completeness limits that allow the detection of individual MS stars down to ~3Mȯ. Here we provide an overview of the crowded field stellar photometry derived for PHAT; full details are found in Dalcanton+ (2012ApJS..200...18D) and Williams+ (2014, J/ApJS/215/9). (1 data file).

  15. Persistência da imagem metastática pulmonary após tratamento de doença trofoblástica gestacional Persisting metastatic pulmonar imaging after treatment of gestational trophoblastic disease

    Directory of Open Access Journals (Sweden)

    Eddie Fernando Candido Murta

    1999-01-01

    Full Text Available O objetivo deste relato é a apresentação de um caso de doença trofoblástica gestacional com metástases pulmonares, cujas imagens persistiram após a normalização dos títulos de fração beta do hormônio da gonadotrofina coriônica (beta-hCG após cinco ciclos de quimioterapia (metotrexato, 20 mg/dia por 5 dias a cada 14 dias. A paciente foi submetida a ressecção das lesões por toracoscopia vídeo-assistida. O exame histológico demonstrou necrose sem evidência de tumor residual. É importante reconhecer que a persistência de nódulos pulmonares em pacientes com doença trofoblástica gestacional metastática após tratamento e normalização do beta-hCG pode não representar tumor viável mas somente necrose e/ou fibrose.The aim of this report is to present one case of gestational trophoblastic disease with pulmonary metastases apparently persisting despite the return of beta-human chorionic gonadotropin (beta-hCG to normal levels after five cycles of chemotherapy (20 mg methotrexate/day for 5 days. The patient was submitted to a video-assisted thoracoscopy and the nodules were excised. Histological examination showed tissue necrosis without evidence of residual tumor. It is important to recognize that persistent nodules in the lungs of patients with metastatic gestational disease after treatment and normal beta-hCG titers may not represent viable tumor but rather necrosis and/or fibrosis.

  16. [Serum beta 2 microglobulin (beta 2M) following renal transplantation].

    Science.gov (United States)

    Pacheco-Silva, A; Nishida, S K; Silva, M S; Ramos, O L; Azjen, H; Pereira, A B

    1994-01-01

    Although there was an important improvement in graft and patient survival the last 10 years, graft rejection continues to be a major barrier to the success of renal transplantation. Identification of a laboratory test that could help to diagnose graft rejection would facilitate the management of renal transplanted patients. PURPOSE--To evaluate the utility of monitoring serum beta 2M in recently transplanted patients. METHODS--We daily determined serum beta 2M levels in 20 receptors of renal grafts (10 from living related and 10 from cadaveric donors) and compared them to their clinical and laboratory evolution. RESULTS--Eight patients who presented immediate good renal function following grafting and did not have rejection had a mean serum beta 2M of 3.7 mg/L on the 4th day post transplant. The sensitivity of the test for the diagnosis of acute rejection was 87.5%, but the specificity was only 46%. Patients who presented acute tubular necrosis (ATN) without rejection had a progressive decrease in their serum levels of beta 2M, while their serum creatinine changed as they were dialyzed. In contrast, patients with ATN and concomitance of acute rejection or CSA nephrotoxicity presented elevated beta 2M and creatinine serum levels. CONCLUSION--Daily monitoring of serum beta 2M does not improve the ability to diagnose acute rejection in patients with good renal function. However, serum beta 2M levels seemed to be useful in diagnosing acute rejection or CSA nephrotoxicity in patients with ATN.

  17. Temperature of neutron stars

    Science.gov (United States)

    Tsuruta, Sachiko

    2016-07-01

    We start with a brief introduction to the historical background in the early pioneering days when the first neutron star thermal evolution calculations predicted the presence of neutron stars hot enough to be observable. We then report on the first detection of neutron star temperatures by ROSAT X-ray satellite, which vindicated the earlier prediction of hot neutron stars. We proceed to present subsequent developments, both in theory and observation, up to today. We then discuss the current status and the future prospect, which will offer useful insight to the understanding of basic properties of ultra-high density matter beyond the nuclear density, such as the possible presence of such exotic particles as pion condensates.

  18. Stars resembling the Sun

    Science.gov (United States)

    Cayrel de Strobel, G.

    This review is primarily directed to the question whether photometric solar analogues remain such when subjected to detailed spectroscopic analyses and interpreted with the help of internal stucture models. In other words, whether the physical parameters: mass, chemical composition, age (determining effective temperature and luminosity), chromospheric activity, equatorial rotation, lithium abundance, velocity fields etc., we derive from the spectral analysis of a photometric solar analogue, are really close to those of the Sun. We start from 109 photometric solar analogues extracted from different authors. The stars selected had to satisfy three conditions: i) their colour index (B-V) must be contained in the interval: Δ (B-V) = 0.59-0.69, ii) they must possess a trigonometric parallax, iii) they must have undergone a high resolution detailed spectroscopic analysis. First, this review presents photometric and spectrophotometric researches on solar analogues and recalls the pionneering work on these stars by the late Johannes Hardorp. After a brief discussion on low and high resolution spectroscopic researches, a comparison is made between effective temperatures as obtained, directly, from detailed spectral analyses and those obtained, indirectly, from different photometric relations. An interesting point in this review is the discussion on the tantalilizing value of the (B-V)solar of the Sun, and the presentation of a new reliable value of this index. A short restatement of the kinematic properties of the sample of solar analogues is also made. And, finally, the observational ( T eff, M bol) diagram, obtained with 99 of the initially presented 109 analogues, is compared to a theoretical ( T eff, M bol) diagram. This latter has been constructed with a grid of internal structure models for which, (very important for this investigation), the Sun was used as gauge. In analysing the position, with respect to the Sun, of each star we hoped to find a certain number of

  19. Notes on Star Formation

    CERN Document Server

    Krumholz, Mark R

    2015-01-01

    This book provides an introduction to the field of star formation at a level suitable for graduate students or advanced undergraduates in astronomy or physics. The structure of the book is as follows. The first two chapters begin with a discussion of observational techniques, and the basic phenomenology they reveal. The goal is to familiarize students with the basic techniques that will be used throughout, and to provide a common vocabulary for the rest of the book. The next five chapters provide a similar review of the basic physical processes that are important for star formation. Again, the goal is to provide a basis for what follows. The remaining chapters discuss star formation over a variety of scales, starting with the galactic scale and working down to the scales of individual stars and their disks. The book concludes with a brief discussion of the clearing of disks and the transition to planet formation. The book includes five problem sets, complete with solutions.

  20. Spectroscopy among the stars.

    Science.gov (United States)

    Winnewisser, G

    1996-06-01

    The space between the stars is not void, but filled with interstellar matter, mainly composed of dust and gas, which gather in large interstellar clouds. In our Galaxy these interstellar clouds are distributed along a thin, but extended layer which basically traces out the spiral distribution of matter: the stars, the gas, and the dust component. Up to the present time more than 100 different molecules have been identified in interstellar molecular clouds. The majority of the interstellar molecules constitute carbon containing organic substances. During the past years, overwhelming evidence has been gathered, mainly through spectroscopic observations, that interstellar molecular clouds provide the birthplaces for stars. In fact detailed high spectral and spatial resolution spectroscopic measurements reveal physical and chemical processes of the intricate star formation process.

  1. Interferometric star tracker Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Optical Physics Company (OPC) proposes to develop a high accuracy version of its interferometric star tracker capable of meeting the milli-arcsecond-level pointing...

  2. Sports Stars Shine

    Institute of Scientific and Technical Information of China (English)

    Yu Yan

    2012-01-01

    Alive and exciting award ceremony drew the attention of numerous Chinese households on the night of January 15.The most popular Chinese sports stars attended the 2011 CCTV Sports Personality Award Ceremony at the National Indoor Stadium in Beijing.

  3. Neutron Stars Recent Developments

    CERN Document Server

    Heiselberg, H

    1999-01-01

    Recent developments in neutron star theory and observation are discussed. Based on modern nucleon-nucleon potentials more reliable equations of state for dense nuclear matter have been constructed. Furthermore, phase transitions such as pion, kaon and hyperon condensation, superfluidity and quark matter can occur in cores of neutron stars. Specifically, the nuclear to quark matter phase transition and its mixed phases with intriguing structures is treated. Rotating neutron stars with and without phase transitions are discussed and compared to observed masses, radii and glitches. The observations of possible heavy $\\sim 2M_\\odot$ neutron stars in X-ray binaries and QPO's require relatively stiff equation of states and restrict strong phase transitions to occur at very high nuclear densities only.

  4. Worlds around other stars

    Science.gov (United States)

    Black, David C.

    1991-01-01

    The possible, though tentative, detection of planetary companions to other stars which may be capable of supporting life as we know it through the use of a new generation of detectors and telescopes, combined with some innovative detection techniques, is discussed. The current view of the origin of the solar system, based on the nebular hypothesis, is discussed as it pertains to the formation of how and where planets form and, hence, how and where to search for them. Both direct methods of search for other planetary systems, which involve detecting reflected light or infrared radiation form the planets themselves, and indirect methods, which involve the scrutinization of a star for signs that it is responding to the gravitational tug of an orbiting planet, are discussed at length. In particular, various methods for detecting minute velocity perturbations of stars are discussed. It is noted that the study of brown dwarfs may also provide clues on the formation of stars and planets.

  5. The JCMT Gould Belt Survey: Evidence for Dust Grain Evolution in Perseus Star-forming Clumps

    CERN Document Server

    Chen, Michael Chun-Yuan; Johnstone, D; Sadavoy, S; Hatchell, J; Mottram, J C; Kirk, H; Buckle, J; Berry, D S; Broekhoven-Fiene, H; Currie, M J; Fich, M; Jenness, T; Nutter, D; Pattle, K; Pineda, J E; Quinn, C; Salji, C; Tisi, S; Hogerheijde, M R; Ward-Thompson, D; Bastien, P; Bresnahan, D; Butner, H; Chrysostomou, A; Coude, S; Davis, C J; Drabek-Maunder, E; Duarte-Cabral, A; Fiege, J; Friberg, P; Friesen, R; Fuller, G A; Graves, S; Greaves, J; Gregson, J; Holland, W; Joncas, G; Kirk, J M; Knee, L B G; Mairs, S; Marsh, K; Matthews, B C; Moriarty-Schieven, G; Mowat, C; Pezzuto, S; Rawlings, J; Richer, J; Robertson, D; Rosolowsky, E; Rumble, D; Schneider-Bontemps, N; Thomas, H; Tothill, N; Viti, S; White, G J; Wouterloot, J; Yates, J; Zhu, M

    2016-01-01

    The dust emissivity spectral index, $\\beta$, is a critical parameter for deriving the mass and temperature of star-forming structures, and consequently their gravitational stability. The $\\beta$ value is dependent on various dust grain properties, such as size, porosity, and surface composition, and is expected to vary as dust grains evolve. Here we present $\\beta$, dust temperature, and optical depth maps of the star-forming clumps in the Perseus Molecular Cloud determined from fitting SEDs to combined Herschel and JCMT observations in the 160 $\\mu$m, 250 $\\mu$m, 350 $\\mu$m, 500 $\\mu$m, and 850 $\\mu$m bands. Most of the derived $\\beta$, and dust temperature values fall within the ranges of 1.0 - 2.7 and 8 - 20 K, respectively. In Perseus, we find the $\\beta$ distribution differs significantly from clump to clump, indicative of grain growth. Furthermore, we also see significant, localized $\\beta$ variations within individual clumps and find low $\\beta$ regions correlate with local temperature peaks, hinting a...

  6. Chaotic Star Birth

    Science.gov (United States)

    2005-01-01

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Click on the image for Poster VersionClick on the image for IRAS 4B Inset Located 1,000 light years from Earth in the constellation Perseus, a reflection nebula called NGC 1333 epitomizes the beautiful chaos of a dense group of stars being born. Most of the visible light from the young stars in this region is obscured by the dense, dusty cloud in which they formed. With NASA's Spitzer Space Telescope, scientists can detect the infrared light from these objects. This allows a look through the dust to gain a more detailed understanding of how stars like our sun begin their lives. The young stars in NGC 1333 do not form a single cluster, but are split between two sub-groups. One group is to the north near the nebula shown as red in the image. The other group is south, where the features shown in yellow and green abound in the densest part of the natal gas cloud. With the sharp infrared eyes of Spitzer, scientists can detect and characterize the warm and dusty disks of material that surround forming stars. By looking for differences in the disk properties between the two subgroups, they hope to find hints of the star and planet formation history of this region. The knotty yellow-green features located in the lower portion of the image are glowing shock fronts where jets of material, spewed from extremely young embryonic stars, are plowing into the cold, dense gas nearby. The sheer number of separate jets that appear in this region is unprecedented. This leads scientists to believe that by stirring up the cold gas, the jets may contribute to the eventual dispersal of the gas cloud, preventing more stars from forming in NGC 1333. In contrast, the upper portion of the image is dominated by the infrared light from warm dust, shown as red.

  7. Alkaline broadening in Stars

    CERN Document Server

    De Kertanguy, A

    2015-01-01

    Giving new insight for line broadening theory for atoms with more structure than hydrogen in most stars. Using symbolic software to build precise wave functions corrected for ds;dp quantum defects. The profiles obtained with that approach, have peculiar trends, narrower than hydrogen, all quantum defects used are taken from atomic database topbase. Illustration of stronger effects of ions and electrons on the alkaline profiles, than neutral-neutral collision mechanism. Keywords : Stars: fundamental parameters - Atomic processes - Line: profiles.

  8. Structure and expression of the mouse beta-hexosaminidase genes, Hexa and Hexb.

    Science.gov (United States)

    Yamanaka, S; Johnson, O N; Norflus, F; Boles, D J; Proia, R L

    1994-06-01

    Two genes, HEXA and HEXB, encode the alpha- and beta-subunits, respectively, of human beta-hexosaminidase. In the mouse, the corresponding genes are termed Hexa and Hexb. The subunits dimerize to yield three isozymes, beta-hexosaminidase A (alpha beta), B (beta beta), and S (alpha alpha), that have the capacity to degrade a variety of substrates containing beta-linked N-acetylglucosamine and N-acetylgalactosamine residues. Mutations in the HEXA or HEXB gene resulting in a beta-hexosaminidase deficiency cause Tay-Sachs or Sandhoff disease, respectively. As a prelude to the creation of mouse models of these lysosomal storage diseases, we have characterized the molecular biology of the mouse beta-hexosaminidase system. Protein sequences derived from the cloned Hexa and Hexb cDNAs were 55% identical to each other and were also very similar to the cognate human sequences: 84% sequence identity with human HEXA and 75% with HEXB. The mouse hexosaminidase subunits, when expressed in HeLa cells from the cDNAs, displayed specificity toward synthetic substrates similar to the human subunits. The Hexa and Hexb genes were 25 and 22 kb in length, respectively. Each gene was divided into 14 exons, with the positions of introns precisely matching those of the corresponding human genes. The 5' flanking regions of the mouse genes demonstrated promoter activity as ascertained by their ability to drive chloramphenicol acetyltransferase gene expression in transfected NIH 3T3 cells. The sequences of these regulatory regions were G+C-rich in the 200 bp upstream of the respective initiator ATGs. Several putative promoter elements were present, including Sp1, AP2, CAAT, and TATA motifs.(ABSTRACT TRUNCATED AT 250 WORDS)

  9. A spectroscopic orbit for the late-type Be star β CMi

    Science.gov (United States)

    Dulaney, Nick; Richardson, Noel; Gerhartz, Cody; Bjorkman, Jon Eric; Bjorkman, Karen S.; Carciofi, Alex C.; Wang, Luqian; Morrison, Nancy D.; Klement, Robert; Ritter Observing Team

    2017-01-01

    The late-type Be star beta CMi is remarkably stable compared to other Be stars that have been studied. This has led to a realistic model of the outflowing Be disk by Klement et al. (2015) These results showed that the disk is likely truncated at a finite radius from the star, which is easily accomplished by a binary companion in orbit. We report on an analysis of the Ritter Observatory spectroscopic archive of beta CMi in hopes of discovering evidence of the elusive companion. We detect orbital motion caused by a companion from small shifts in the H-alpha emission line. We then compared the small changes in the violet-to-red peak height changes (V/R) with the orbital motion. While some V/R variability seems to be present in the H-alpha profile, there is only weak evidence that it follows the orbital motion, as suggested by recent Be binary models by Panoglou et al. (2016). We also analyze several epochs of near-infrared moderate resolution spectra from the InfraRed Telescope Facility with the SpeX spectrograph. Near-infrared spectra show variations of the Pa-beta and Br-gamma lines, suggesting structure could be present in the inner parts of the Be disk. These results suggest that beta CMi is similar to several other Be stars, and is a product of binary evolution where Roche lobe overflow has spun up the current Be star, likely leaving a hot subdwarf or white dwarf in orbit around the star. Unfortunately, no sign of this star is found in the very limited archive of International Ultraviolet Explorer spectra, so future UV studies of the system are necessary.We are grateful for support of the NSF REU program at the University of Toledo through NSF grant 1262810 and addtional support from the NSF under grant AST-1412135.

  10. Blockade of PKC-beta protects HUVEC from advanced glycation end products induced inflammation.

    Science.gov (United States)

    Xu, Youhua; Wang, Shanshan; Feng, Liang; Zhu, Quan; Xiang, Ping; He, Bao

    2010-12-01

    Advanced glycation end products (AGEs) have been recognized as a pivotal inducer in diabetes and kinds of aging-related vasculopathy. Endothelial dysfunction and inflammatory cells adhesion to endothelium have been regarded as important and early factors in the pathogenesis of vascular complications in diabetic patients. Owing to the key role of PKC-beta in AGEs-induced vascular dysfunction, we investigated effects of blocking PKC-beta by LY333531 on macrophage adhesion to HUVEC and the related mechanism. Transwell HUVEC-macrophage co-culture system was established to evaluate macrophage migration and adhesion ability. Immunocytochemistry was applied to examine TGF-beta1, ICAM-1 and RAGE protein expressions by SABC or SABC-AP method; mRNA expression of TGF-beta1, ICAM-1 and RAGE was determined by real-time RT-PCR. SOD and MDA levels in culture supernatant were detected. We found that LY333531 significantly reduced AGEs-induced macrophage adhesion to HUVEC. Blockade of PKC-beta strikingly decreased HUVEC TGF-beta1 and ICAM-1 expression in both protein and mRNA levels, RAGE protein level was also down-regulated. Furthermore, the anti-oxidative stress index, SOD/MDA was dramatically elevated on LY333531 application. Therefore we conclude that LY333531 can reduce AGEs-induced macrophage adhesion to endothelial cells and relieve the local inflammation, this was realized by its effect on decreasing inflammatory cytokines' expression and increasing cell anti-oxidative ability.

  11. Systematic interactome mapping and genetic perturbation analysis of a C. elegans TGF-beta signaling network.

    Science.gov (United States)

    Tewari, Muneesh; Hu, Patrick J; Ahn, Jin Sook; Ayivi-Guedehoussou, Nono; Vidalain, Pierre-Olivier; Li, Siming; Milstein, Stuart; Armstrong, Chris M; Boxem, Mike; Butler, Maurice D; Busiguina, Svetlana; Rual, Jean-François; Ibarrola, Nieves; Chaklos, Sabrina T; Bertin, Nicolas; Vaglio, Philippe; Edgley, Mark L; King, Kevin V; Albert, Patrice S; Vandenhaute, Jean; Pandey, Akhilesh; Riddle, Donald L; Ruvkun, Gary; Vidal, Marc

    2004-02-27

    To initiate a system-level analysis of C. elegans DAF-7/TGF-beta signaling, we combined interactome mapping with single and double genetic perturbations. Yeast two-hybrid (Y2H) screens starting with known DAF-7/TGF-beta pathway components defined a network of 71 interactions among 59 proteins. Coaffinity purification (co-AP) assays in mammalian cells confirmed the overall quality of this network. Systematic perturbations of the network using RNAi, both in wild-type and daf-7/TGF-beta pathway mutant animals, identified nine DAF-7/TGF-beta signaling modifiers, seven of which are conserved in humans. We show that one of these has functional homology to human SNO/SKI oncoproteins and that mutations at the corresponding genetic locus daf-5 confer defects in DAF-7/TGF-beta signaling. Our results reveal substantial molecular complexity in DAF-7/TGF-beta signal transduction. Integrating interactome maps with systematic genetic perturbations may be useful for developing a systems biology approach to this and other signaling modules.

  12. Resolved Star Formation on Sub-galactic Scales in a Merger at z=1.7

    CERN Document Server

    Whitaker, Katherine E; Brammer, Gabriel B; Gladders, Michael D; Sharon, Keren; Teng, Stacy H; Wuyts, Eva

    2014-01-01

    We present a detailed analysis of Hubble Space Telescope (HST), Wide Field Camera 3 (WFC3) G141 grism spectroscopy for seven star-forming regions of the highly magnified lensed star- burst galaxy RCSGA 032727-132609 at z = 1.704. We measure the spatial variations of the extinction in RCS0327 through the observed H$\\gamma$/H$\\beta$ emission line ratios, finding a constant average extinction of $E(B-V)_{gas} = 0.40\\pm0.07$. We infer that the star formation is enhanced as a result of an ongoing interaction, with measured star formation rates derived from demagnified, extinction-corrected Hbeta line fluxes for the individual star-forming clumps falling >1-2 dex above the star formation sequence. When combining the HST/WFC3 [OIII] $\\lambda$5007/H$\\beta$ emission line ratio measurements with [NII]/H$\\alpha$ line ratios from Wuyts et al. (2014), we find that the majority of the individual star-forming regions fall along the local "normal" abundance sequence. With the first detections of the He I $\\lambda$5876 $\\AA$ ...

  13. The Star Formation History of Local Starbursts as Benchmark for High Redshifts

    Science.gov (United States)

    Schmitt, Henrique R.; Calzetti, Daniela; Armus, Lee

    2001-08-01

    We propose to use the WIYN telescope and MIMO to obtain broad band B and R, and narrow band H(alpha) and H(beta) images for a sample of 13 local starburst galaxies detected by ISO at 170-200(micron) and for which we are obtaining ultraviolet (1600Å) images with an approved HST/STIS program. With these observations we will complete the ground based portion of this project. This sample spans a wide range in the luminosity, star formation rate, metallicity and morphology parameters, and will be used as a low-redshift benchmark to explore the relationship between the Lyman-break and the SCUBA galaxies at z~3. The broad- band ground-based and HST images will be used to characterize the stellar populations and determine the ages of the star forming regions of these galaxies, while the H(alpha)/H(beta) ratio will be used to determine the reddening and gas morphology of these regions. We will study the conditions for the escape of UV light from a dusty galaxy, as a function of the sample parameters. The H(alpha) and UV HST images will be combined to derive a relative empirical calibration between these two star formation indicators. We will measure the fraction of nuclear and disk emission, the fraction of star formation in massive clusters and the properties of those star clusters, the structural properties of star forming bars, rings, and tidally-driven star formation in IR-bright galaxies.

  14. New Results of Spectral Observations of CP Stars in the Li I 6708 Å Spectral Region with the 6-m BTA Telescope

    Science.gov (United States)

    Polosukhina, N.; Shavrina, A.; Drake, N.; Kudryavtsev, D.; Smirnova, M.

    The lithium problem in Ap-CP stars has for a long time been a subject of debates. Individual characteristics of CP stars, such as a high abundance of rare-earth elements, the presence of magnetic fields, complex structures of the surface distribution of chemical elements, rapid oscillations of some CP stars, make the detection of lithium lines, and determination of lithium abundance a challenging task. The lithium problem in Ap-CP stars was discussed during the meeting in Slovakia in 1996. The results of the Li study, carried out in CrAO (Polosukhina, 1973 - 1976), the works of Faraggiana & Hack (1963), Wallerstein & Hack (1964), Faraggiana et al. (1992 - 1996) formed the basis of the international project, called Lithium in the Cool CP Stars with Magnetic Fields. The main goal of the project was, using systematical observations of Ap-CP stars with phase rotation in the spectral regions of the resonance doublet Li I 6708 Å and subordinate 6104 Å lithium lines with different telescopes, to create a database, which will permit to explain the physical origin of the anomalous Li abundance in the atmospheres of these stars.

  15. On the progenitor of the Type Ic supernova 2002ap

    NARCIS (Netherlands)

    Smartt, SJ; Ramirez-Ruiz, E; Gilmore, GF; Meikle, WPS; Ferguson, AMN; Knapen, JH

    2002-01-01

    This Letter presents wide-field optical and near-IR (UBVRIHalphaK') images of the galaxy M74 that were taken between 0.6 and 8.3 yr before the discovery of the Type Ic supernova 2002ap. We have located the position of the supernova on these images with an accuracy of 0."3. We find no sign of a proge

  16. A Low-Power CoAP for Contiki

    OpenAIRE

    Kovatsch M.; Duquennoy S.; Dunkels A.

    2011-01-01

    Internet of Things devices will by and large be battery-operated, but existing application protocols have typically not been designed with power-efficiency in mind. In low-power wireless systems, power-efficiency is determined by the ability to maintain a low radio duty cycle: keeping the radio off as much as possible. We present an implementation of the IETF Constrained Application Protocol (CoAP) for the Contiki operating system that leverages the ContikiMAC low-powe...

  17. Characteristics of shigellosis outbreaks in the AP of Vojvodina

    OpenAIRE

    2009-01-01

    Introduction. Shigellosis causes around 165 million infections and around 1 million deaths in the world every year. Two thirds of both infections and deaths are among children younger than 10. Shigellosis mainly spreads by direct or indirect contact, but water- and food-borne outbreaks are not rare. Material and methods. A descriptive epidemiological method was used to analyse characteristics of shigellosis outbreaks in the AP of Vojvodina in the period 1979-2005. Results. During this period ...

  18. Essay: Computers in the APS Editorial Office: The Early Years

    Science.gov (United States)

    Adams, Peter

    2009-03-01

    APS journals in the late 1960s began to move from hot-metal print shops to tailor-made typewriters, next to special keyboards and a small computer, then to completely photocomposed journal pages. At the same time, internal editorial operations were being converted from paper handling and data records to completely electronic procedures. By 1990, it became feasible for authors to submit manuscripts to the journal electronically.

  19. Photometric Observations of 6000 Stars in the Cygnus Field

    Science.gov (United States)

    Borucki, W.; Caldwell, D.; Koch, D.; Jenkins, J.; Ninkov, Z.

    1999-01-01

    transits a much larger primary. However when high-resolution spectra were obtained for both stars, the stars were found to be double-lined binaries so similar in size as to have indistinguishable transit depths. The low amplitude of the transits is explained if the stellar orbital planes are tipped approximately 5 degrees from the line of sight causing both binaries to show grazing transits. The two absorption lines, due to the H(sub beta) feature in each star, are apparent and indicate the presence of a binary system with similar components.

  20. New Photometrically Variable Magnetic Chemically Peculiar Stars in the ASAS-3 Archive

    CERN Document Server

    Hümmerich, Stefan; Bernhard, Klaus

    2016-01-01

    The magnetic Ap or CP2 stars are natural atomic and magnetic laboratories and ideal testing grounds for the evaluation of model atmospheres. CP2 stars exhibiting photometric variability are traditionally referred to as alpha2 Canum Venaticorum (ACV) variables. Strictly periodic changes are observed in the spectra and brightness of these stars, which allow the derivation of rotational periods. Related to this group of objects are the He-weak (CP4) and He-rich stars, some of which are also known to undergo brightness changes due to rotational modulation. Increasing the sample size of known rotational periods among CP2/4 stars is an important task, which will contribute to our understanding of these objects and their evolution in time. We have compiled an extensive target list of magnetic chemically peculiar (CP2/4) stars. In addition to that, a systematic investigation of early-type (spectral types B/A) variable stars of undetermined type in the International Variable Star Index of the AAVSO (VSX) yielded addit...

  1. Magnetic, chemically peculiar (CP2) stars in the SuperWASP survey

    Science.gov (United States)

    Bernhard, K.; Hümmerich, S.; Paunzen, E.

    2015-12-01

    The magnetic chemically peculiar (CP2) stars of the upper main sequence are well-suited for investigating the impact of magnetic fields on the surface layers of stars, which leads to abundance inhomogeneities (spots) resulting in photometric variability. The light changes are explained in terms of the oblique rotator model; the derived photometric periods thus correlate with the rotational periods of the stars. CP2 stars exhibiting this kind of variability are classified as α2 Canum Venaticorum (ACV) variables. We have analysed around 3 850 000 individual photometric WASP measurements of magnetic chemically peculiar (CP2) stars and candidates selected from the catalogue of Ap, HgMn, and Am stars, with the ultimate goal of detecting new ACV variables. In total, we found 80 variables, from which 74 are reported here for the first time. The data allowed us to establish variability for 23 stars which had been reported as probably constant in the literature before. Light curve parameters were obtained for all stars by a least-squares fit with the fundamental sine wave and its first harmonic. Because of the scarcity of Strömgren uvbyβ measurements and the lack of parallax measurements with an accuracy better than 20%, we are not able to give reliable astrophysical parameters for the investigated objects.

  2. Long-term stability of the APS storage ring

    Energy Technology Data Exchange (ETDEWEB)

    Friedsam, H.; Penicka, M.; Error, J.

    1999-10-26

    The Advanced Photon Source (APS), a third-generation synchrotrons light source, was commissioned in 1995 at Argonne ''National Laboratory and has been fully-operational for beamline users since 1997. The APS storage ring can accommodate up to 68 user beamlines; about 70% of the available beamlines are currently in use by various collaborative access teams (CATS). The 7-GeV synchrotrons light source produces light in the soft to hard x-ray range that is used for research in such areas as x-ray instrumentation; material, chemical and atomic sciences; biology; and geo/soil/ environmental sciences. For the successful operation of an x-ray light source such as the Advanced Photon Source, the long-term stability of the concrete floor supporting the beam components and user beamlines is crucial. Settlements impact the orbit and location of the x-ray source points as well as the position of the x-ray beamlines. This paper compares the results of two successive resurveys of the APS accelerator components performed in 1995 and 1998.

  3. AP Theory IV: Intrinsic Topological Quantum Langlands Theory

    CERN Document Server

    Winkelnkemper, H E

    2010-01-01

    Without using any moduli, sheaves, stacks, nor any analytic, nor category-type arguments, we exhibit an analogue to Geometric Langlands Theory in an entirely model-independent, non-perturbative,purely smooth topological context in Artin Presentation Theory. A basic initial feature is that AP Theory, as a whole, is already, ab initio, a universal canonical 2D sigma-model, targeting smooth, compact, simply-connected 4-manifolds with a connected boundary, and its topological Planckian quantum starting point, as well as its cone-like, infinitely-generated at each stage, graded group of homology-preserving, but topology-changing transitions/interactions, exhibit the most general qualitative S-duality. We first point out the numerous mathematically rigorous, model-free, (i.e., intrinsic), topological AP analogues with the heuristic Kapustin-Witten version of Geometric Langlands theory, as well as the crucial differences between the two theories. The latter have to exist since AP Theory deals, a priori, essentially ...

  4. Experiments on double beta decay

    Energy Technology Data Exchange (ETDEWEB)

    Busto, J. [Neuchatel Univ. (Switzerland). Inst. de Physique

    1996-11-01

    The Double Beta Decay, and especially ({beta}{beta}){sub 0{nu}} mode, is an excellent test of Standard Model as well as of neutrino physics. From experimental point of view, a very large number of different techniques are or have been used increasing the sensitivity of this experiments quite a lot (the factor of 10{sup 4} in the last 20 years). In future, in spite of several difficulties, the sensitivity would be increased further, keeping the interest of this very important process. (author) 4 figs., 5 tabs., 21 refs.

  5. VizieR Online Data Catalog: Abundances of bright metal-poor stars (Schlaufman+, 2014)

    Science.gov (United States)

    Schlaufman, K. C.; Casey, A. R.

    2016-11-01

    As input to our sample selection, we use the APASS DR6 Catalog, the 2MASS All-Sky Point Source Catalog, and the AllWISE Source Catalog (Henden+ 2012JAVSO..40..430H; Skrutskie+ 2006AJ....131.1163S; Wright+ 2010AJ....140.1868W; Mainzer+ 2011ApJ...731...53M). We followed up our metal-poor star candidates with the Mayall 4m/Echelle, Gemini South/GMOS-S, and Magellan/MIKE telescopes and spectrographs. We observed 98 stars with the Mayall 4m/Echelle on 2013 June 25-27. We observed 90 stars with Gemini South/GMOS-S in service mode from 2014 March to July (R~3700). We observed 416 stars with Magellan/MIKE on 2014 June 21-23 and July 8-10 (R~41000 in the blue and R~35000 in the red). (3 data files).

  6. Dosimetry of {beta} extensive sources; Dosimetria de fuentes {beta} extensas

    Energy Technology Data Exchange (ETDEWEB)

    Rojas C, E.L.; Lallena R, A.M. [Departamento de Fisica Moderna, Universidad de Granada, E-18071 Granada (Spain)

    2002-07-01

    In this work, we have been studied, making use of the Penelope Monte Carlo simulation code, the dosimetry of {beta} extensive sources in situations of spherical geometry including interfaces. These configurations are of interest in the treatment of the called cranealfaringyomes of some synovia leisure of knee and other problems of interest in medical physics. Therefore, its application can be extended toward problems of another areas with similar geometric situation and beta sources. (Author)

  7. A Heavy Flavor Tracker for STAR

    Energy Technology Data Exchange (ETDEWEB)

    Chasman, C.; Beavis, D.; Debbe, R.; Lee, J.H.; Levine, M.J.; Videbaek, F.; Xu, Z.; Kleinfelder, S.; Li, S.; Cendejas, R.; Huang, H.; Sakai, S.; Whitten, C.; Joseph, J.; Keane, D.; Margetis, S.; Rykov, V.; Zhang, W.M.; Bystersky, M.; Kapitan, J.; Kushpil, V.; Sumbera, M.; Baudot, J.; Hu-Guo, C.; Shabetai, A.; Szelezniak, M.; Winter, M.; Kelsey, J.; Milner, R.; Plesko, M.; Redwine, R.; Simon, F.; Surrow, B.; Van Nieuwenhuizen, G.; Anderssen, E.; Dong, X.; Greiner, L.; Matis, H.S.; Morgan, S.; Ritter, H.G.; Rose, A.; Sichtermann, E.; Singh, R.P.; Stezelberger, T.; Sun, X.; Thomas, J.H.; Tram, V.; Vu, C.; Wieman, H.H.; Xu, N.; Hirsch, A.; Srivastava, B.; Wang, F.; Xie, W.; Bichsel, H.

    2008-02-25

    The STAR Collaboration proposes to construct a state-of-the-art microvertex detector,the Heavy Flavor Tracker (HFT), utilizing active pixel sensors and silicon strip technology. The HFT will significantly extend the physics reach of the STAR experiment for precision measurement of the yields and spectra of particles containing heavy quarks. This will be accomplished through topological identification of D mesons by reconstruction of their displaced decay vertices with a precision of approximately 50 mu m in p+p, d+A, and A+A collisions. The HFT consists of 4 layers of silicon detectors grouped into two sub-systems with different technologies, guaranteeing increasing resolution when tracking from the TPC and the Silicon Strip Detector (SSD) towards the vertex of the collision. The Intermediate Silicon Tracker (IST), consisting of two layers of single-sided strips, is located inside the SSD. Two layers of Silicon Pixel Detector (PIXEL) are inside the IST. The PIXEL detectors have the resolution necessary for a precision measurement of the displaced vertex. The PIXEL detector will use CMOS Active Pixel Sensors (APS), an innovative technology never used before in a collider experiment. The APSsensors are only 50 mu m thick and at a distance of only 2.5 cm from the interaction point. This opens up a new realm of possibilities for physics measurements. In particular, a thin detector (0.28percent radiation length per layer) in STAR makes it possible to do the direct topological reconstruction of open charm hadrons down to very low pT by the identification of the charged daughters of the hadronic decay.

  8. Life Cycle of Stars

    Science.gov (United States)

    1999-01-01

    In this stunning picture of the giant galactic nebula NGC 3603, the crisp resolution of NASA's Hubble Space Telescope captures various stages of the life cycle of stars in one single view. To the upper left of center is the evolved blue supergiant called Sher 25. The star has a unique circumstellar ring of glowing gas that is a galactic twin to the famous ring around the supernova 1987A. The grayish-bluish color of the ring and the bipolar outflows (blobs to the upper right and lower left of the star) indicates the presence of processed (chemically enriched) material. Near the center of the view is a so-called starburst cluster dominated by young, hot Wolf-Rayet stars and early O-type stars. A torrent of ionizing radiation and fast stellar winds from these massive stars has blown a large cavity around the cluster. The most spectacular evidence for the interaction of ionizing radiation with cold molecular-hydrogen cloud material are the giant gaseous pillars to the right of the cluster. These pillars are sculptured by the same physical processes as the famous pillars Hubble photographed in the M16 Eagle Nebula. Dark clouds at the upper right are so-called Bok globules, which are probably in an earlier stage of star formation. To the lower left of the cluster are two compact, tadpole-shaped emission nebulae. Similar structures were found by Hubble in Orion, and have been interpreted as gas and dust evaporation from possibly protoplanetary disks (proplyds). This true-color picture was taken on March 5, 1999 with the Wide Field Planetary Camera 2.

  9. Testing the companion hypothesis for the origin of the X-ray emission from intermediate-mass main-sequence stars

    CERN Document Server

    Stelzer, B; Micela, G; Hubrig, S

    2006-01-01

    There is no straightforward explanation for intrinsic X-ray emission from intermediate-mass main-sequence stars. Therefore the observed emission is often interpreted in terms of (hypothesized) late-type magnetically active companion stars. We use Chandra imaging observations to spatially resolve in X-rays a sample of main-sequence B-type stars with recently discovered companions at arcsecond separation. We find that all spatially resolved companions are X-ray emitters, but seven out of eleven intermediate-mass stars are also X-ray sources. If this emission is interpreted in terms of additional sub-arcsecond or spectroscopic companions, this implies a high multiplicity of B-type stars. Firm results on B star multiplicity pending, the alternative, that B stars produce intrinsic X-rays, can not be discarded. The appropriate scenario in this vein is might be a magnetically confined wind, as suggested for the X-ray emission of the magnetic Ap star IQ Aur. However, the only Ap star in the Chandra sample is not dete...

  10. Magnetic Doppler imaging of the chemically peculiar star HD 125248

    Science.gov (United States)

    Rusomarov, N.; Kochukhov, O.; Ryabchikova, T.; Ilyin, I.

    2016-04-01

    Context. Intermediate-mass, chemically peculiar stars with strong magnetic fields provide an excellent opportunity to study the topology of their surface magnetic fields and the interplay between magnetic geometries and abundance inhomogeneities in the atmospheres of these stars. Aims: We reconstruct detailed maps of the surface magnetic field and abundance distributions for the magnetic Ap star HD 125248. Methods: We performed the analysis based on phase-resolved, four Stokes parameter spectropolarimetric observations obtained with the HARPSpol instrument. These data were interpreted with the help of magnetic Doppler imaging techniques and model atmospheres taking the effects of strong magnetic fields and nonsolar chemical composition into account. Results: We improved the atmospheric parameters of the star, Teff = 9850 ± 250 K and log g = 4.05 ± 0.10. We performed detailed abundance analysis, which confirmed that HD 125248 has abundances typical of other Ap stars, and discovered significant vertical stratification effects for the Fe ii and Cr ii ions. We computed LSD Stokes profiles using several line masks corresponding to Fe-peak and rare earth elements, and studied their behavior with rotational phase. Combining previous longitudinal field measurements with our own observations, we improved the rotational period of the star Prot = 9.29558 ± 0.00006 d. Magnetic Doppler imaging of HD 125248 showed that its magnetic field is mostly poloidal and quasi-dipolar with two large spots of different polarity and field strength. The chemical maps of Fe, Cr, Ce, Nd, Gd, and Ti show abundance contrasts of 0.9-3.5 dex. Among these elements, the Fe abundance map does not show high-contrast features. Cr is overabundant around the negative magnetic pole and has 3.5 dex abundance range. The rare earth elements and Ti are overabundant near the positive magnetic pole. Conclusions: The magnetic field of HD 125248 has strong deviations from the classical oblique dipole field

  11. An Analysis of the Rapidly Rotating Bp star HD 133880

    Science.gov (United States)

    Bailey, J. D.; Grunhut, J.; Shultz, M.; Wade, G.; Landstreet, J. D.; Bohlender, D.; Lim, J.; Wong, K.; Drake, S.; Linsky, J.

    2012-01-01

    HD 133880 is a rapidly rotating chemically peculiar B-type (Bp) star (nu sin i approx = 103km/s) and is host to one of the strongest magnetic fields of any Ap/Bp star. A member of the Upper Centaurus Lupus association, it is a star with a well-determined age of 16 Myr. 12 new spectra, four of which are polarimetric, obtained from the FEROS, ESPaDOnS and HARPS instruments, provide sufficient material from which to re-evaluate the magnetic field and obtain a first approximation to the atmospheric abundance distributions of He, O, Mg, Si, Ti. Cr, Fe, Ni, Pr and Nd. An abundance analysis was carried out using ZEEMAN, a program which synthesizes spectral line profiles for stars with permeating magnetic fields. The magnetic field structure was characterized by a colinear multipole expansion from the observed variations of the longitudinal and surface fields with rotational phase. Both magnetic hemispheres are clearly visible during the stellar rotation, and thus a three-ring abundance distribution model encompassing both magnetic poles and magnetic equator with equal spans in colatitude was adopted. Using the new magnetic field measurements and optical photometry together with previously published data, we refine the period of HD 133880 to P = 0.877 476 +/- 0.000009 d. Our simple axisymmetric magnetic field model is based on a predominantly quadrupolar component that roughly describes the field variations. Using spectrum synthesis, we derived mean abundances for O, Mg, Si, Ti, Cr, Fe and Pr. All elements; except Mg, are overabundant compared to the Son. Mg appears to be approximately uniform over the stellar surface, while all other elements are more abundant in the negative magnetic hemisphere than in the positive magnetic hemisphere. In contrast to most Ap/Bp stars which show an underabundance in 0, in HD 133880 this element is clearly overabundant compared to the solar abundance ratio. In studying the Ha and Paschen lines in the optical spectra, we could not

  12. Evolution of outer membrane beta-barrels from an ancestral beta beta hairpin.

    Science.gov (United States)

    Remmert, M; Biegert, A; Linke, D; Lupas, A N; Söding, J

    2010-06-01

    Outer membrane beta-barrels (OMBBs) are the major class of outer membrane proteins from Gram-negative bacteria, mitochondria, and plastids. Their transmembrane domains consist of 8-24 beta-strands forming a closed, barrel-shaped beta-sheet around a central pore. Despite their obvious structural regularity, evidence for an origin by duplication or for a common ancestry has not been found. We use three complementary approaches to show that all OMBBs from Gram-negative bacteria evolved from a single, ancestral beta beta hairpin. First, we link almost all families of known single-chain bacterial OMBBs with each other through transitive profile searches. Second, we identify a clear repeat signature in the sequences of many OMBBs in which the repeating sequence unit coincides with the structural beta beta hairpin repeat. Third, we show that the observed sequence similarity between OMBB hairpins cannot be explained by structural or membrane constraints on their sequences. The third approach addresses a longstanding problem in protein evolution: how to distinguish between a very remotely homologous relationship and the opposing scenario of "sequence convergence." The origin of a diverse group of proteins from a single hairpin module supports the hypothesis that, around the time of transition from the RNA to the protein world, proteins arose by amplification and recombination of short peptide modules that had previously evolved as cofactors of RNAs.

  13. The Adolescent Novel in AP English: A Response to Patricia Spencer.

    Science.gov (United States)

    McGee, Tim

    1992-01-01

    Discusses the absence of adolescent literature in Advanced Placement (AP) English classes. Describes how a class of AP students and their teacher benefited from reading Robert Cormier's "The Chocolate War." (PRA)

  14. Recombinant thermostable AP exonuclease from Thermoanaerobacter tengcongensis: cloning, expression, purification, properties and PCR application

    DEFF Research Database (Denmark)

    Dabrowski, Slawomir; Brillowska-Dabrowska, Anna; Ahring, Birgitte Kiær

    2013-01-01

    Apurinic/apyrimidinic (AP) sites in DNA are considered to be highly mutagenic and must be corrected to preserve genetic integrity, especially at high temperatures. The gene encoding a homologue of AP exonuclease was cloned from the thermophilic anaerobic bacterium Thermoanaerobacter tengcongensis...... (14000 kU) of pure His6-tagged Tte AP (153 kU/mg) from 1 liter of culture. The optimal conditions of Tte AP endo-, exonuclease and 3'-nuclease activity were investigated using fluorescein labeled dsDNA with inserted AP sites and ssDNA. Optimal Tte AP endonuclease activity was observed at 70-75 degrees C...... DNA templates. Tte AP exonuclease eliminated AP-sites in DNA template and improved the efficiency of DNA amplification....

  15. NRC confirmatory AP600 safety system phase I testing in the ROSA/AP600 test facility

    Energy Technology Data Exchange (ETDEWEB)

    Rhee, G.S.; Kukita, Yutaka; Schultz, R.R.

    1996-03-01

    The NRC confirmatory phase I testing for the AP600 safety systems has been completed in the modified ROSA (Rig of Safety Assessment) test facility located at the Japan Atomic Energy Research Institute (JAERI) campus in Tokai, Japan. The test matrix included a variety of accident scenarios covering both design and beyond-design basis accidents. The test results indicate the AP600 safety systems as reflected in ROSA appear to perform as designed and there is no danger of core heatup for the accident scenarios investigated. In addition, no detrimental system interactions nor adverse effects of non-safety systems on the safety system functions were identified. However, three phenomena of interest have been identified for further examination to determine whether they are relevant to the AP600 plant. Those three phenomena are: (1) a potential for water hammer caused by rapid condensation which may occur following the actuation of the automatic depressurization system (ADS), (2) a large thermal gradient in the cold leg pipe where cooled water returns from the passive residual heat removal system and forms a thermally stratified layer, and (3) system-wide oscillations initiating following the ADS stage 4 actuation and persisting until the liquid in the pressurizer drains and steam generation in the core becomes insignificant.

  16. Questions Students Ask: Beta Decay.

    Science.gov (United States)

    Koss, Jordan; Hartt, Kenneth

    1988-01-01

    Answers a student's question about the emission of a positron from a nucleus. Discusses the problem from the aspects of the uncertainty principle, beta decay, the Fermi Theory, and modern physics. (YP)

  17. Dark Stars: A Review

    CERN Document Server

    Freese, Katherine; Spolyar, Douglas; Valluri, Monica

    2015-01-01

    Dark Stars (DS) are stellar objects made (almost entirely) of ordinary atomic material but powered by the heat from Dark Matter (DM) annihilation (rather than by fusion). Weakly Interacting Massive Particles (WIMPs), among the best candidates for DM, can be their own antimatter and can accumulate inside the star, with their annihilation products thermalizing with and heating the DS. The resulting DSs are in hydrostatic and thermal equilibrium. The first phase of stellar evolution in the history of the Universe may have been dark stars. Though DM constituted only $10^6 M_\\odot$), very bright ($>10^9 L_\\odot$), and potentially detectable with the James Webb Space Telescope (JWST). Once the DM runs out and the dark star dies, it may collapse to a black hole; thus DSs can provide seeds for the supermassive black holes observed throughout the Universe and at early times. Other sites for dark star formation exist in the Universe today in regions of high dark matter density such as the centers of galaxies. The curre...

  18. Stars, Galaxies and Quasars

    Directory of Open Access Journals (Sweden)

    Patrick Das Gupta

    2009-05-01

    Full Text Available This article provides a brief introduction to the basics of stars, galaxies and Quasi-stellar objects (QSOs. In stars, the central pressure and temperature must be high in order to halt the stellar gravitational collapse. High temperature leads to thermonuclear fusion in the stellar core, releasing thereby enormous amount of nuclear energy, making the star shine brilliantly. On the other hand, the QSOs are very bright nuclei lying in the centres of some galaxies. Many of these active galactic nuclei, which appear star-like when observed through a telescope and  whose power output are more than 1011 times that of the Sun, exhibit rapid time variability in their X-ray emissions.  Rapid variability along with the existence of a maximum speed limit, c, provide a strong argument in favour of a compact central engine model for QSOs in which a thick disc of hot gas going around a supermassive blackhole is what makes a QSO appear like a bright point source. Hence, unlike stars, QSOs are powered by gravitational potential energy.

  19. Hot subluminous stars

    CERN Document Server

    Heber, Ulrich

    2016-01-01

    Hot subluminous stars of spectral type B and O are core helium-burning stars at the blue end of the horizontal branch or have evolved even beyond that stage. Strikingly, the distribution in the Hertzsprung-Russell diagram of He-rich vs. He-poor hot subdwarf stars of the globular clusters omega Cen and NGC~2808 differ from that of their field counterparts. The metal-abundance patterns of hot subdwarfs are typically characterized by strong deficiencies of some lighter elements as well as large enrichments of heavy elements. A large fraction of sdB stars are found in close binaries with white dwarf or very low-mass main sequence companions, which must have gone through a common-envelope phase of evolution.They provide a clean-cut laboratory to study this important but yet purely understood phase of stellar evolution. Substellar companions to sdB stars have also been found. For HW~Vir systems the companion mass distribution extends from the stellar into the brown dwarf regime. A giant planet to the pulsator V391 ...

  20. Circulation of Stars

    Science.gov (United States)

    Boitani, P.

    2016-01-01

    Since the dawn of man, contemplation of the stars has been a primary impulse in human beings, who proliferated their knowledge of the stars all over the world. Aristotle sees this as the product of primeval and perennial “wonder” which gives rise to what we call science, philosophy, and poetry. Astronomy, astrology, and star art (painting, architecture, literature, and music) go hand in hand through millennia in all cultures of the planet (and all use catasterisms to explain certain phenomena). Some of these developments are independent of each other, i.e., they take place in one culture independently of others. Some, on the other hand, are the product of the “circulation of stars.” There are two ways of looking at this. One seeks out forms, the other concentrates on the passing of specific lore from one area to another through time. The former relies on archetypes (for instance, with catasterism), the latter constitutes a historical process. In this paper I present some of the surprising ways in which the circulation of stars has occurred—from East to West, from East to the Far East, and from West to East, at times simultaneously.

  1. Young Stars with SALT

    CERN Document Server

    Riedel, Adric R; Rice, Emily L; Cruz, Kelle L; Henry, Todd J

    2016-01-01

    We present a spectroscopic and kinematic analysis of 79 nearby M dwarfs in 77 systems. All are low-proper-motion southern hemisphere objects and were identified in a nearby star survey with a demonstrated sensitivity to young stars. Using low-resolution optical spectroscopy from the Red Side Spectrograph (RSS) on the South African Large Telescope (SALT), we have determined radial velocities, H-alpha, Lithium 6708\\AA, and Potassium 7699\\AA~equivalent widths linked to age and activity, and spectral types for all our targets. Combined with astrometric information from literature sources, we identify 44 young stars. Eighteen are previously known members of moving groups within 100 parsecs of the Sun. Twelve are new members, including one member of the TW Hydra moving group, one member of the 32 Orionis moving group, nine members of Tucana-Horologium, one member of Argus, and two new members of AB Doradus. We also find fourteen young star systems that are not members of any known groups. The remaining 33 star syst...

  2. Beta Function and Anomalous Dimensions

    CERN Document Server

    Pica, Claudio

    2010-01-01

    We demonstrate that it is possible to determine the coefficients of an all-order beta function linear in the anomalous dimensions using as data the two-loop coefficients together with the first one of the anomalous dimensions which are universal. The beta function allows to determine the anomalous dimension of the fermion masses at the infrared fixed point, and the resulting values compare well with the lattice determinations.

  3. Stars a very short introduction

    CERN Document Server

    King, Andrew

    2012-01-01

    Stars: A Very Short Introduction looks at how stars live, producing all the chemical elements beyond helium, and how they die, leaving remnants such as black holes. Every atom of our bodies has been part of a star. Our very own star, the Sun, is crucial to the development and sustainability of life on Earth. Understanding stars is key to understanding the galaxies they inhabit, the existence of planets, and the history of our entire Universe. This VSI explores the science of stars, the mechanisms that allow them to form, the processes that allow them to shine, and the results of their death.

  4. FRANX. Application for analysis and quantification of the APS fire; FRANK. Aplicacion para el analisis y cuantificacion de los APS de incendios

    Energy Technology Data Exchange (ETDEWEB)

    Snchez, A.; Osorio, F.; Ontoso, N.

    2014-07-01

    The FRANX application has been developed by EPRI within the Risk and Reliability User Group in order to facilitate the process of quantification and updating APS Fire (also covers floods and earthquakes). By applying fire scenarios are quantified in the central integrating the tasks performed during the APS fire. This paper describes the main features of the program to allow quantification of an APS Fire. (Author)

  5. VizieR Online Data Catalog: Kepler δ Sct stars amplitude modulation (Bowman+, 2016)

    Science.gov (United States)

    Bowman, D. M.; Kurtz, D. W.; Breger, M.; Murphy, S. J.; Holdsworth, D. L.

    2016-06-01

    We searched for amplitude modulation of pulsation modes in δ Sct stars observed by the Kepler Space Telescope. The number of pulsation modes out of a maximum of twelve that have constant amplitudes and variable amplitudes are given in the columns NoMod and AMod, respectively, along with stellar parameters from Huber et al. (2014, Cat. J/ApJS/211/2). Table 1 is the full version for all 983 δ Sct stars the abridged version of the paper. (1 data file).

  6. {beta}-decay studies of r-process nuclei at NSCL

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, J. [National Superconducting Cyclotron Laboratory, Michigan State University, E. Lansing, MI (United States); Joint Institute for Nuclear Astrophysics, Michigan State University, E. Lansing, MI (United States)], E-mail: pereira@nscl.msu.edu; Aprahamian, A. [Institute of Structure and Nuclear Astrophysics, University of Notre Dame, South Bend, IN (United States); Joint Institute for Nuclear Astrophysics, University of Notre Dame, South Bend, IN (United States); Arndt, O. [Institut fuer Kernchemie, Universitaet Mainz, Mainz (Germany); Virtuelles Institut fuer Struktur der Kerne and Nuklearer Astrophysik, Mainz (Germany); Becerril, A.; Elliot, T. [National Superconducting Cyclotron Laboratory, Michigan State University, E. Lansing, MI (United States); Joint Institute for Nuclear Astrophysics, Michigan State University, E. Lansing, MI (United States); Estrade, A. [National Superconducting Cyclotron Laboratory, Michigan State University, E. Lansing, MI (United States); Joint Institute for Nuclear Astrophysics, Michigan State University, E. Lansing, MI (United States); Department of Physics and Astronomy, Michigan State University, E. Lansing, MI (United States); Galaviz, D. [National Superconducting Cyclotron Laboratory, Michigan State University, E. Lansing, MI (United States); Joint Institute for Nuclear Astrophysics, Michigan State University, E. Lansing, MI (United States); Hennrich, S. [Institut fuer Kernchemie, Universitaet Mainz, Mainz (Germany); Virtuelles Institut fuer Struktur der Kerne and Nuklearer Astrophysik, Mainz (Germany); Hosmer, P. [National Superconducting Cyclotron Laboratory, Michigan State University, E. Lansing, MI (United States); Joint Institute for Nuclear Astrophysics, Michigan State University, E. Lansing, MI (United States); Department of Physics and Astronomy, Michigan State University, E. Lansing, MI (United States)] (and others)

    2008-06-01

    Observed neutron-capture elemental abundances in metal-poor stars, along with ongoing analysis of the extremely metal-poor Eu-enriched sub-class provide new guidance for astrophysical models aimed at finding the r-process sites. The present paper emphasizes the importance of nuclear physics parameters entering in these models, particularly {beta}-decay properties of neutron-rich nuclei. In this context, several r-process motivated {beta}-decay experiments performed at the National Superconducting Cyclotron Laboratory (NSCL) are presented, including a summary of results and impact on model calculations.

  7. Determination of chromatographic and spectrophotometric dissociation constants of some beta lactam antibiotics.

    Science.gov (United States)

    Demiralay, Ebru Çubuk; Koç, Duygu; Daldal, Y Doğan; Cakır, Cansel

    2012-12-01

    In this work, dissociation constants values of seven beta lactam antibiotics in water and acetonitrile-water mixtures using spectrophotometric and reversed phase liquid chromatography methods were determined. The dissociation constant values of these compounds were calculated by NLREG and STAR programs. Aqueous pK(a) values of beta lactam antibiotics were calculated with extrapolation by means of the Yasuda-Shedlovsky and mole fraction equations. Finally, application of the different techniques was compared to the determination of aqueous pK(a) values of investigated compounds.

  8. A Preferred Home for Disrupted Stars

    Science.gov (United States)

    Kohler, Susanna

    2016-07-01

    shows the authors model for NGC 3156 (assuming different masses for its central black hole), and the black curve shows the power-law best fit for a large galaxy sample. NGC 3156s predicted TDE rate is an order of magnitude higher that of a typical galaxy. [Stone van Velzen 2016]Collisions in a Crowded NucleusBy analyzing Hubble Space Telescope photometry of NGC 3156, Stone and van Velzen determine that there is an overdensity of stars in the central region of the galaxy which is expected to be the case for all E+A galaxies, due to their starburst history. The authors next use their measurements and arguments of stellar density and dynamics to calculate a predicted rate of two-body starstar interactions that lead to TDEs.Stone and van Velzen predict that TDEs from two-body interactions should occur at a rate of ~10-3 per year in NGC 3156. This is an order of magnitude larger than the rate that the same calculations would predict for a typical galaxy (10-4 per year).The authors observations and analysis of NGC 3156 strongly support the idea that E+A galaxies overproduce TDEs because their very dense centers created by past starbursts provide a highly collisional environment, allowing more starstar interactions. These interactions can then lead to stellar orbits that plunge near the supermassive black hole at the galactic center, producing TDEs.CitationNicholas C. Stone and Sjoert van Velzen 2016 ApJ 825 L14. doi:10.3847/2041-8205/825/1/L14

  9. Highly compact neutron stars in scalar-tensor theories of gravity: spontaneous scalarization vs. gravitational collapse

    CERN Document Server

    Mendes, Raissa F P

    2016-01-01

    Scalar-tensor theories of gravity are extensions of General Relativity (GR) including an extra, nonminimally coupled scalar degree of freedom. A wide class of these theories, albeit indistinguishable from GR in the weak field regime, predicts a radically different phenomenology for neutron stars, due to a nonperturbative, strong-field effect referred to as spontaneous scalarization. This effect is known to occur in theories where the effective linear coupling $\\beta_0$ between the scalar and matter fields is sufficiently negative, i.e. $\\beta_0 \\lesssim -4.35$, and has been strongly constrained by pulsar timing observations. In the test-field approximation, spontaneous scalarization manifests itself as a tachyonic-like instability. Recently, it was argued that, in theories where $\\beta_0>0$, a similar instability would be triggered by sufficiently compact neutron stars obeying realistic equations of state. In this work we investigate the endstate of this instability for some representative coupling functions ...

  10. AP Studio Art as an Enabling Constraint for Secondary Art Education

    Science.gov (United States)

    Graham, Mark A.

    2009-01-01

    Advanced Placement (AP) Studio Art is an influential force in secondary art education as is evident in the 31,800 portfolios submitted for review in 2008. From the perspectives of a high school educator and AP Reader, this author has observed how the constraints of the AP program can be used to generate support for high school art programs and…

  11. Using a Classroom Response System to Improve Multiple-Choice Performance in AP[R] Physics

    Science.gov (United States)

    Bertrand, Peggy

    2009-01-01

    Participation in rigorous high school courses such as Advanced Placement (AP[R]) Physics increases the likelihood of college success, especially for students who are traditionally underserved. Tackling difficult multiple-choice exams should be part of any AP program because well-constructed multiple-choice questions, such as those on AP exams and…

  12. Polypeptides having beta-glucosidase activity, beta-xylosidase activity, or beta-glucosidase and beta-xylosidase activity and polynucleotides encoding same

    Energy Technology Data Exchange (ETDEWEB)

    Morant, Marc

    2017-02-07

    The present invention relates to isolated polypeptides having beta-glucosidase activity, beta-xylosidase activity, or beta-glucosidase and beta-xylosidase activity and isolated polynucleotides encoding the polypeptides. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the polynucleotides as well as methods of producing and using the polypeptides.

  13. HD 101065, the Most Peculiar Star: First Results from Precise Radial Velocity Study

    Indian Academy of Sciences (India)

    D. E. Mkrtichian; A. P. Hatzes

    2005-06-01

    In this paper we discuss the prospects for asteroseismology with spatial resolution and motivate studies of the most chemically peculiar roAp star HD 101065. We present the first results from a high-precision radial velocity (RV) study of HD 101065 based on data spanning four nights that were acquired using the HARPS echelle-spectrometer at the ESO 3.6 m telescope. The analysis of individual nights showed the amplitude and phase modulation of the dominant mode. The analysis of the whole data set showed the presence of multi-periodic oscillations with two groups of equally-spaced modes. We find = 65.2 Hz and = 7.3 Hz for the large and the small spacing, respectively. HD 101065 is the only roAp star to show the existence of two groups of = 0, 2 and = 1, 3 excited modes.

  14. Far Ultraviolet Spectra of B Stars near the Ecliptic

    CERN Document Server

    Morales, C; Gómez, J F; Trapero, J; Talavera, A; Bowyer, S; Edelstein, J D; Korpela, E J; Lampton, M; Drake, J J

    2000-01-01

    Spectra of B stars in the wavelength range of 911-1100 A have been obtained with the EURD spectrograph onboard the Spanish satellite MINISAT-01 with ~5 A spectral resolution. IUE spectra of the same stars have been used to normalize Kurucz models to the distance, reddening and spectral type of the corresponding star. The comparison of 8 main-sequence stars studied in detail (alpha Vir, epsilon Tau, lambda Tau, tau Tau, alpha Leo, zeta Lib, theta Oph, and sigma Sgr) shows agreement with Kurucz models, but observed fluxes are 10-40% higher than the models in most cases. The difference in flux between observations and models is higher in the wavelength range between Lyman alpha and Lyman beta. We suggest that Kurucz models underestimate the FUV flux of main-sequence B stars between these two Lyman lines. Computation of flux distributions of line-blanketed model atmospheres including non-LTE effects suggests that this flux underestimate could be due to departures from LTE, although other causes cannot be ruled ou...

  15. Quenching of Star Formation in Molecular Outflow Host NGC 1266

    CERN Document Server

    Alatalo, K; Graves, G; Deustua, S; Young, L M; Davis, T A; Bureau, M; Bayet, E; Blitz, L; Bois, M; Bournaud, F; Cappellari, M; Davies, R L; de Zeeuw, P T; Emsellem, E; Khochfar, S; Krajnovic, D; Kuntschner, H; McDermid, R M; Morganti, R; Naab, T; Oosterloo, T; Sarzi, M; Scott, N; Serra, P; Weijmans, A

    2012-01-01

    We detail the rich molecular story of NGC 1266, its serendipitous discovery within the ATLAS3D survey (Cappellari et al. 2011) and how it plays host to an AGN-driven molecular outflow, potentially quenching all of its star formation (SF) within the next 100 Myr. While major mergers appear to play a role in instigating outflows in other systems, deep imaging of NGC 1266 as well as stellar kinematic observations from SAURON, have failed to provide evidence that NGC 1266 has recently been involved in a major interaction. The molecular gas and the instantaneous SF tracers indicate that the current sites of star formation are located in a hypercompact disk within 200 pc of the nucleus (Fig. 1; SF rate ~ 2 Msuns/yr). On the other hand, tracers of recent star formation, such as the H{\\beta} absorption map from SAURON and stellar population analysis show that the young stars are distributed throughout a larger area of the galaxy than current star formation. As the AGN at the center of NGC 1266 continues to drive cold...

  16. Plant-specific insertions in the soybean aspartic proteinases, soyAP1 and soyAP2, perform different functions of vacuolar targeting.

    Science.gov (United States)

    Terauchi, Kaede; Asakura, Tomiko; Ueda, Haruko; Tamura, Tomoko; Tamura, Kentaro; Matsumoto, Ichiro; Misaka, Takumi; Hara-Nishimura, Ikuko; Abe, Keiko

    2006-07-01

    Most aspartic proteinases (APs) of plant origin are characterized by the presence of plant-specific insertion (PSI) in their primary structure. PSI has been reported to function as signals for both transport of AP molecules from the endoplasmic reticulum (ER) and for their targeting to the vacuole. To determine the functions of the PSIs in soyAP1 and soyAP2 identified in our previous study, we examined their subcellular localization by transient expression of a green fluorescent protein (GFP) fusion protein in the protoplasts of Arabidopsis suspension-cultured cells. Both soyAP1-GFP and soyAP2-GFP were targeted to the vacuole. To confirm the role of the PSI, we prepared PSI-deleted soyAP1 and soyAP2, and investigated their vacuolar targeting by the same method. While the former deletion mutant was always transported to the vacuole, the latter sometimes remained in the ER and was only sometimes transported to the vacuole. These observations indicated that, in the case of soyAP1, the PSI is not involved in vacuolar targeting, also suggesting that the function of the PSI differs depending on its origin.

  17. Global Star Formation Rates in Disk Galaxies and Circumnuclear Starbursts from Cloud Collisions

    CERN Document Server

    Tan, J C

    1999-01-01

    We invoke star formation triggered by cloud-cloud collisions to explain global star formation rates of disk galaxies and circumnuclear starbursts. Previous theories based on the growth rate of gravitational perturbations ignore the dynamically important presence of magnetic fields. Theories based on triggering by spiral density waves fail to explain star formation in systems without such waves. Furthermore, observations suggest gas and stellar disk instabilities are decoupled. Following the numerical work of Gammie, Jog & Ostriker (1991), the cloud collision rate is set by the shear velocity of encounters with initial impact parameters of a few tidal radii, due to differential rotation in the disk. This enhances the collision rate above that calculated from simply considering the random velocities of clouds. We predict Sigma_{SFR}(R) is proportional to Sigma_{gas} Omega (1 - 0.7 beta). In the case of constant circular velocity (beta = 0), this is in agreement with recent observations (Kennicutt 1998). We ...

  18. Equation of state and thickness of the inner crust of neutron stars

    CERN Document Server

    Grill, Fabrizio; Providência, Constança; Vidaña, Isaac; Avancini, Sidney S

    2014-01-01

    The cell structure of $\\beta$-stable clusters in the inner crust of cold and warm neutron stars is studied within the Thomas-Fermi approach using relativistic mean field nuclear models. The relative size of the inner crust and the pasta phase of neutron stars is calculated, and the effect of the symmetry energy slope parameter, $L$, on the profile of the neutron star crust is discussed. It is shown that while the size of the total crust is mainly determined by the incompressibility modulus, the relative size of the inner crust depends on $L$. It is found that the inner crust represents a larger fraction of the total crust for smaller values of $L$. Finally, it is shown that at finite temperature the pasta phase in $\\beta$-equilibrium matter essentially melts above $5-6$ MeV, and that the onset density of the rodlike and slablike structures does not depend on the temperature.

  19. Helium stratification in HD 145792: a new Helium strong star

    CERN Document Server

    Catanzaro, G

    2007-01-01

    In this paper we report on the real nature of the star HD 145792, classified as He weak in {\\it ``The General Catalogue of Ap and Am stars''}. By means of FEROS@ESO1.52m high resolution spectroscopic data, we refined the atmospheric parameters of the star, obtaining: T$_{\\rm eff}$ = 14400 $\\pm$ 400 K, $\\log g$ = 4.06 $\\pm$ 0.08 and $\\xi$ = 0 $^{+0.6}$ km s$^{-1}$. These values resulted always lower than those derived by different authors with pure photometric approaches. Using our values we undertook an abundance analysis with the aim to derive, for the first time, the chemical pattern of the star's atmosphere. For metals a pure LTE synthesis (ATLAS9 and SYNTHE) has been used, while for helium a hybrid approach has been preferred (ATLAS9 and SYNSPEC). The principal result of our study is that HD 145792 belongs to He strong class contrary to the previous classification. Moreover, helium seems to be vertically stratified in the atmosphere, decreasing toward deepest layers. For what that concerns metals abundanc...

  20. Magnetic Doppler imaging of the chemically peculiar star HD 125248

    CERN Document Server

    Rusomarov, N; Ryabchikova, T; Ilyin, I

    2016-01-01

    Intermediate-mass, chemically peculiar stars with strong magnetic fields give us an excellent opportunity to study the topology of their surface magnetic fields and the interplay between magnetic geometries and abundance inhomogeneities in their atmospheres. We reconstruct detailed maps of the surface magnetic field and abundance distributions for the magnetic Ap star HD 125248. We performed the analysis based on phase-resolved, four Stokes parameter spectropolarimetric observations obtained with the HARPSpol instrument. These data were interpreted with the magnetic Doppler imaging technique. We improved the atmospheric parameters of the star, T_eff = 9850K +/- 250K and logg = 4.05 +/- 0.10. We performed detailed abundance analysis and discovered vertical stratification effects for the FeII and CrII ions. We computed LSD Stokes profiles and studied their behavior with rotational phase. We improved the rotational period of the star P_rot = 9.29558(6)d. Magnetic Doppler imaging of HD 125248 showed that its magn...