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Sample records for ap star hd101065

  1. HD 101065, the Most Peculiar Star

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... 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 ...

  2. HD 101065, the Most Peculiar Star: First Results from Precise Radial ...

    Indian Academy of Sciences (India)

    The roAp stars are a unique group of pulsators that present us with advantages for asteroseismic studies ... Another important advantage in asteroseismology of roAp stars is the possibility of the spatial filtration of ... (2004) yield a longitudinal magnetic field strength of half the value, or Hz = −1014±. 72 Gauss. HD 101065 ...

  3. HD 101065, the Most Peculiar Star: First Results from Precise Radial ...

    Indian Academy of Sciences (India)

    fact that elements on the surface of Ap (including roAp) stars are distributed inhomo- geneously. Spectroscopic radial velocity measurements of elements that have a spotted distribution on the surface .... 4. Discussion and conclusion. A remarkable feature of the oscillation spectrum of HD 101065 is the existence of two.

  4. HD 101065, the Most Peculiar Star: First Results from Precise Radial ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... 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 ...

  5. Pulsation of Ap-Stars

    Science.gov (United States)

    Weiss, W. W.; Schneider, H.

    1983-09-01

    It has been known for many centuries that one can determine by simple means if a barrel of wine is full, half empty, or- horribile dictu - empty. One knocks against the wall and listens to the echo. Another example of the same technique, but less interesting for the connaisseur en vin is given by seismology. Seismographs distributed all over the globe register earthquakes and since they are differently located with respect to an earthquake centre the registrations look different. From a comparison of such registrations geologists have extracted most of our knowledge about the structure and composition of the terrestrial interior. Corresponding experiments were also planned and successfully executed on the Moon and on Mars. Stellar astronomers, however, are not in the lucky position of their colleagues who work in our solar system with the help of satellites. They are limited to stars which pulsate voluntarily. We will not discuss here the question why some groups of stars pulsate and others do not. We shall only mention that pulsating stars have at least one layer in their interior which does not absorb pulsational energy, as is the case for the rest of the star, but produces energy of variable amount and in phase with PUlsation. This mechanism keeps the star pulsating as long as this (these) layer(s) exists. Oue to stellar evolution, diffusion, magnetic fields, to name only some possible mechanisms, these layers can disappear or undergo substantial changes so that the energy losses due to pulsation cannot be compensated anymore. Oamping will result and finally the star will become stable against pulsation.

  6. Asteroseismic Theory of Rapidly Oscillating Ap Stars

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Astrophysics and Astronomy; Volume 26; Issue 2-3. Asteroseismic Theory of Rapidly Oscillating Ap Stars. Margarida S. Cunha. Volume 26 Issue 2-3 June-September 2005 pp 213-221. Fulltext. Click here to view fulltext PDF. Permanent link:

  7. 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...

  8. The Dushak–Erekdag Survey of roAp Stars

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... 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 ...

  9. Asteroseismic Theory of Rapidly Oscillating Ap Stars Margarida S ...

    Indian Academy of Sciences (India)

    roAp) stars depends strongly on our ability to understand their oscillation spectra. Questions like: which modes are excited and why, what is the expected spacing between eigenfrequencies, how many components are expected to be found in ...

  10. The heterogeneity of surfaces of magnetic Ap stars

    International Nuclear Information System (INIS)

    Hack, M.

    1977-01-01

    The observations of spectrum-variability and light-variability of Ap stars are reviewed. It is shown that these variations are interpretable as due to the changing aspect of the spotted surface as the star rotates. It is stressed that the geometry of the phenomenon is understood fairly well but the physics is very far from being understood. (Auth.)

  11. Autonomous star tracker based on active pixel sensors (APS)

    Science.gov (United States)

    Schmidt, U.

    2017-11-01

    Star trackers are opto-electronic sensors used onboard of satellites for the autonomous inertial attitude determination. During the last years, star trackers became more and more important in the field of the attitude and orbit control system (AOCS) sensors. High performance star trackers are based up today on charge coupled device (CCD) optical camera heads. The Jena-Optronik GmbH is active in the field of opto-electronic sensors like star trackers since the early 80-ties. Today, with the product family ASTRO5, ASTRO10 and ASTRO15, all marked segments like earth observation, scientific applications and geo-telecom are supplied to European and Overseas customers. A new generation of star trackers can be designed based on the APS detector technical features. The measurement performance of the current CCD based star trackers can be maintained, the star tracker functionality, reliability and robustness can be increased while the unit costs are saved.

  12. Photometric and Spectroscopic studies of Ap star Cyg V1584

    Directory of Open Access Journals (Sweden)

    D. M. Z Jassur

    2001-06-01

    Full Text Available   UBV photometric observations of Ap star Cyg V1584 have been presented. To find the rotational period of the star, a sinusoidal wave function has been fitted to the noramal points of UBV filters. Assuming that a circular hot spot located at the magnetic pole of the star is responsible for the observed light variations, both physical an geometrical parameters of the spot have been determined. Finally, the angle between the magnetic and the rotational axis has been calculated from combining the spectroscopic and photometric data and the magnetic structure of the star has been discussed.

  13. A Brightness-Referenced Star Identification Algorithm for APS Star Trackers

    Science.gov (United States)

    Zhang, Peng; Zhao, Qile; Liu, Jingnan; Liu, Ning

    2014-01-01

    Star trackers are currently the most accurate spacecraft attitude sensors. As a result, they are widely used in remote sensing satellites. Since traditional charge-coupled device (CCD)-based star trackers have a limited sensitivity range and dynamic range, the matching process for a star tracker is typically not very sensitive to star brightness. For active pixel sensor (APS) star trackers, the intensity of an imaged star is valuable information that can be used in star identification process. In this paper an improved brightness referenced star identification algorithm is presented. This algorithm utilizes the k-vector search theory and adds imaged stars' intensities to narrow the search scope and therefore increase the efficiency of the matching process. Based on different imaging conditions (slew, bright bodies, etc.) the developed matching algorithm operates in one of two identification modes: a three-star mode, and a four-star mode. If the reference bright stars (the stars brighter than three magnitude) show up, the algorithm runs the three-star mode and efficiency is further improved. The proposed method was compared with other two distinctive methods the pyramid and geometric voting methods. All three methods were tested with simulation data and actual in orbit data from the APS star tracker of ZY-3. Using a catalog composed of 1500 stars, the results show that without false stars the efficiency of this new method is 4∼5 times that of the pyramid method and 35∼37 times that of the geometric method. PMID:25299950

  14. The driving mechanism of roAp stars

    Energy Technology Data Exchange (ETDEWEB)

    Dupret, M-A [Observatoire de Paris, LESIA, CNRS UMR 8109, 5 place J. Janssen, 92195 Meudon (France); Theado, S; Noels, A [Institut d' Astrophysique et Geophysique, Universite de Liege (Belgium)], E-mail: MA.dupret@obspm.fr

    2008-10-15

    We analyse in detail the driving mechanism of roAp stars and present the theoretical instability strip predicted by our models with solar metallicity. A particular attention is given to the interpretation of the role played by the different eigenfunctions in the stabilization of the modes at the red edge of the instability strip. The gradient of temperature in the H{sub I} opacity bump appears to play a major role in this context. We also consider the particular and complex role played by the shape of the eigenfunctions (location of the nodes, ...)

  15. The Dushak–Erekdag Survey of roAp Stars Tatyana Dorokhova ...

    Indian Academy of Sciences (India)

    South-African Astronomical Observatory (SAAO). Details of the discovery and further studies are given in Kurtz (1990) and Kurtz & Martinez (2000). Some roAp stars have multiple modes of pulsations and they are valuable for asteroseismological studies. Out of the 32 known roAp stars so far, about 84% were discovered in ...

  16. Bp- and Ap-stars in the moving Scorpio-Centaurus cluster

    International Nuclear Information System (INIS)

    Klochkova, V.G.; Kopylov, I.M.; Kumajgorodskaya, R.N.

    1981-01-01

    Selection of member-stars of the Scorpio-Centaurus cluster is made in its north-eastern part. 34 Bp- and Ap-stars out of 170 members of the cluster are found. Percentage of Bp- and Ap-stars differs by a factor of 3-4 in different zones of the cluster. The age of stars in different zones is (4-12)x10 6 years. Average distances of stars are estimated (120-145 pc). Spectral characteristics as well as peculiarity type are defined for 17 Bp- and Ap-stars using high resolution spectra. Essential weakening of He1 lines and Mg2 lambda 4481 line is found [ru

  17. Streams and magnetic fields in surface layers of Ap-stars

    International Nuclear Information System (INIS)

    Dolginov, A.Z.; Urpin, V.A.

    1978-01-01

    Magnetic field generation of Ap-stars is considered. It is shown that in the surface layers of Ap-stars inhomogeneity of chemical composition produces a strong magnetic field. Velocities of possible circulation of stellar matter are estimated. It is shown that circulation does not prevent the process of the magnetic field generation. It needs the order of million years, for arranging the stationary magnetic field in surface layers

  18. Large amplitude change in spot-induced rotational modulation of the Kepler Ap star KIC 2569073

    DEFF Research Database (Denmark)

    Drury, Jason A.; Murphy, Simon J.; Derekas, Aliz

    2017-01-01

    An investigation of the 200 x 200 pixel 'superstamp' images of the centres of the open clusters NGC 6791 and NGC 6819 allows for the identification and study of many variable stars that were not included in the Kepler target list. KIC 2569073 (V= 14.22), is a particularly interesting variable Ap...... star that we discovered in the NGC 6791 superstamp. With a rotational period of 14.67 d and 0.034 mag variability, it has one of the largest peak-to-peak variations of any known Ap star. Colour photometry reveals an antiphase correlation between the B band, and the V, R and I bands. This Ap star...... is a rotational variable, also known as an alpha(2) CVn star, and is one of only a handful of Ap stars observed by Kepler. While no change in spot period or amplitude is observed within the 4 yr Kepler time series, the amplitude shows a large increase compared to ground-based photometry obtained two decades ago....

  19. Ap stars with resolved magnetically split lines: Magnetic field determinations from Stokes I and V spectra⋆

    Science.gov (United States)

    Mathys, G.

    2017-05-01

    Context. Some Ap stars that have a strong enough magnetic field and a sufficiently low v sini show spectral lines resolved into their magnetically split components. Aims: We present the results of a systematic study of the magnetic fields and other properties of those stars. Methods: This study is based on 271 new measurements of the mean magnetic field modulus ⟨ B ⟩ of 43 stars, 231 determinations of the mean longitudinal magnetic field ⟨ Bz ⟩ and of the crossover ⟨ Xz ⟩ of 34 stars, and 229 determinations of the mean quadratic magnetic field ⟨ Bq ⟩ of 33 stars. Those data were used to derive new values or meaningful lower limits of the rotation periods Prot of 21 stars. Variation curves of the mean field modulus were characterised for 25 stars, the variations of the longitudinal field were characterised for 16 stars, and the variations of the crossover and of the quadratic field were characterised for 8 stars. Our data are complemented by magnetic measurements from the literature for 41 additional stars with magnetically resolved lines. Phase coverage is sufficient to define the curve of variation of ⟨ B ⟩ for 2 of these stars. Published data were also used to characterise the ⟨ Bz ⟩ curves of variation for 10 more stars. Furthermore, we present 1297 radial velocity measurements of the 43 Ap stars in our sample that have magnetically resolved lines. Nine of these stars are spectroscopic binaries for which new orbital elements were derived. Results: The existence of a cut-off at the low end of the distribution of the phase-averaged mean magnetic field moduli ⟨ B ⟩ av of the Ap stars with resolved magnetically split lines, at about 2.8 kG, is confirmed. This reflects the probable existence of a gap in the distribution of the magnetic field strengths in slowly rotating Ap stars, below which there is a separate population of stars with fields weaker than 2 kG. In more than half of the stars with magnetically resolved lines that have a

  20. The Dushak–Erekdag Survey of roAp Stars Tatyana Dorokhova ...

    Indian Academy of Sciences (India)

    hemisphere from SAAO by Kurtz (1990), Martinez et al. (1991) and Martinez & Kurtz. (1994a, b). In order to investigate the cause for this asymmetric distribution in the two hemispheres of the sky, a number of surveys were carried out for discovering northern. roAp stars (e.g., Matthews & Wehlau 1985; Heller & Kramer 1988; ...

  1. Mining the HST "Advanced Spectral Library (ASTRAL) - Hot Stars": The High Definition UV Spectrum of the Ap Star HR 465

    Science.gov (United States)

    Carpenter, Kenneth G.; Ayres, T. R.; Nielsen, K. E.; Kober, G. V.; Wahlgren, G. M.; Adelman, S. J.; Cowley, C. R.

    2014-01-01

    The "Advanced Spectral Library (ASTRAL) Project: Hot Stars" is a Hubble Space Telescope (HST) Cycle 21 Treasury Program (GO-13346: Ayres PI). It is designed to collect a definitive set of representative, high-resolution ( 30,000-100,000), high signal/noise (S/N>100), and full UV coverage 1200 - 3000 A) spectra of 21 early-type stars, utilizing the high-performance Space Telescope Imaging Spectrograph (STIS). The targets span the range of spectral types between early-O and early-A, including both main sequence and evolved stars, fast and slow rotators, as well as chemically peculiar (CP) and magnetic objects. These extremely high-quality STIS UV echelle spectra will be available from the HST archive and, in post-processed and merged form, at http://casa.colorado.edu ayres/ASTRAL/. The UV "atlases" produced by this program will enable investigations of a broad range of problems -- stellar, interstellar, and beyond -- for many years to come. We offer a first look at one of the earliest datasets to come out of this observing program, a "high definition" UV spectrum of the Ap star HR 465, which was chosen as a prototypical example of an A-type magnetic CP star. HR 465 has a global magnetic field of ~2200 Gauss. Earlier analyses of IUE spectra show strong iron-peak element lines, along with heavy elements such as Ga and Pt, while being deficient in the abundance of some ions of low atomic number, such as carbon. We demonstrate the high quality of the ASTRAL data and present the identification of spectral lines for a number of elements. By comparison of the observed spectra with calculated spectra, we also provide estimates of element abundances, emphasizing heavy elements, and place these measurements in the context of earlier results for this and other Ap stars.

  2. Reduction of low frequency error for SED36 and APS based HYDRA star trackers

    Science.gov (United States)

    Ouaknine, Julien; Blarre, Ludovic; Oddos-Marcel, Lionel; Montel, Johan; Julio, Jean-Marc

    2017-11-01

    In the frame of the CNES Pleiades satellite, a reduction of the star tracker low frequency error, which is the most penalizing error for the satellite attitude control, was performed. For that purpose, the SED36 star tracker was developed, with a design based on the flight qualified SED16/26. In this paper, the SED36 main features will be first presented. Then, the reduction process of the low frequency error will be developed, particularly the optimization of the optical distortion calibration. The result is an attitude low frequency error of 1.1" at 3 sigma along transverse axes. The implementation of these improvements to HYDRA, the new multi-head APS star tracker developed by SODERN, will finally be presented.

  3. Study of Pulsations in the Atmosphere of the roAp star HD 137949

    Science.gov (United States)

    Sachkov, M.; Hareter, M.; Ryabchikova, T.; Wade, G.; Kochukhov, O.; Weiss, W. W.

    The roAp star HD 137949 (33 Lib) shows the most complex pulsational behaviour among all roAp stars. Mkrtichian et al. (2003) found nearly anti-phase pulsations of Nd II and Nd III lines, which they attribute to the presence of a pulsation node high in the atmosphere of HD 137949. This was confirmed by Kurtz at al. (2005), who also find that in some REE lines the main frequency, corresponding to 8.27 min, and its harmonic have almost equal RV amplitudes. Based on high accuracy observations Ryabchikova et al. (2007a) studied pulsational characteristics of the HD 137949 atmosphere in detail. In general, spectroscopy provides 3D resolution of modes and allows to search for the photometrically undetectable frequencies. The high-accuracy space photometry provides very high-precision measurements of detected pulsation frequencies and enables an accurate phasing of multi-site spectroscopic data. A combination of simultaneous spectroscopy and photometry represents the most sophisticated asteroseismic dataset for any roAp star. In 2009 the star HD 137949 became a target of an intense observing campaign that combined ground-based spectroscopy with space photometry, obtained with the MOST satellite. We collected 780 spectra using the ESPaDOnS spectrograph mounted on the 3.6 m CFHT telescope; 374 spectra were obtained with the FIES spectrograph mounted on the 2.56-m NOT to perform the time-resolved spectroscopy of HD 137949. In addition, we used 111 UVES spectra (2004) from the ESO archive to check the mode stability. The frequency analysis of the new radial velocity (RV) measurements confirmed the previously reported frequency pattern (two frequencies and the first harmonic of the main frequency), and revealed an additional frequency at 1.991 mHz. The new frequency solution fits perfectly the RV variations from the 2004 and 2009 observational sets providing a strong support for the p-mode stability in the roAp star HD 137949 for at least 5 years.

  4. The complex magnetic field topology of the cool Ap star 49 Cam

    Science.gov (United States)

    Silvester, J.; Kochukhov, O.; Rusomarov, N.; Wade, G. A.

    2017-10-01

    49 Cam is a cool magnetic chemically peculiar star that has been noted for showing strong, complex Zeeman linear polarization signatures. This paper describes magnetic and chemical surface maps obtained for 49 Cam using the Invers10 magnetic Doppler imaging code and high-resolution spectropolarimetric data in all four Stokes parameters collected with the ESPaDOnS and Narval spectropolarimeters at the Canada-France-Hawaii Telescope and Pic du Midi Observatory. The reconstructed magnetic field maps of 49 Cam show a relatively complex structure. Describing the magnetic field topology in terms of spherical harmonics, we find significant contributions of modes up to ℓ = 3, including toroidal components. Observations cannot be reproduced using a simple low-order multipolar magnetic field structure. 49 Cam exhibits a level of field complexity that has not been seen in magnetic maps of other cool Ap stars. Hence, we concluded that relatively complex magnetic fields are observed in Ap stars at both low and high effective temperatures. In addition to mapping the magnetic field, we also derive surface abundance distributions of nine chemical elements, including Ca, Sc, Ti, Cr, Fe, Ce, Pr, Nd and Eu. Comparing these abundance maps with the reconstructed magnetic field geometry, we find no clear relationship of the abundance distributions with the magnetic field for some elements. However, for other elements some distinct patterns are found. We discuss these results in the context of other recent magnetic mapping studies and theoretical predictions of radiative diffusion.

  5. 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

  6. Models of large-scale magnetic fields in stellar interiors. Application to solar and ap stars

    International Nuclear Information System (INIS)

    Duez, Vincent

    2009-01-01

    Stellar astrophysics needs today new models of large-scale magnetic fields, which are observed through spectropolarimetry at the surface of Ap/Bp stars, and thought to be an explanation for the uniform rotation of the solar radiation zone, deduced from helio seismic inversions. During my PhD, I focused on describing the possible magnetic equilibria in stellar interiors. The found configurations are mixed poloidal-toroidal, and minimize the energy for a given helicity, in analogy with Taylor states encountered in spheromaks. Taking into account the self-gravity leads us to the 'non force-free' equilibria family, that will thus influence the stellar structure. I derived all the physical quantities associated with the magnetic field; then I evaluated the perturbations they induce on gravity, thermodynamic quantities as well as energetic ones, for a solar model and an Ap star. 3D MHD simulations allowed me to show that these equilibria form a first stable states family, the generalization of such states remaining an open question. It has been shown that a large-scale magnetic field confined in the solar radiation zone can induce an oblateness comparable to a high core rotation law. I also studied the secular interaction between the magnetic field, the differential rotation and the meridional circulation in the aim of implementing their effects in a next generation stellar evolution code. The influence of the magnetism on convection has also been studied. Finally, hydrodynamic processes responsible for the mixing have been compared with diffusion and a change of convection's efficiency in the case of a CoRoT star target. (author) [fr

  7. Magnetic field topology and chemical spot distributions of the Ap star HD 119419

    Science.gov (United States)

    Rusomarov, N.; Kochukhov, O.; Lundin, A.

    2018-01-01

    Context. Analysis of high-resolution spectropolarimetric time-series observations of early-type magnetic stars is currently the most advanced method of obtaining detailed information on their surface magnetic field topologies and horizontal spot distributions. Aims: In this study we analyse a new set of high-quality full Stokes vector observations of the magnetic Ap star HD 119419 - a member of the 14 Myr old Lower Cen-Cru association - for the purpose of studying the surface field topology and mapping the chemical abundance spots. Methods: We made use of the circular and linear polarisation data collected for HD 119419 with the HARPSpol instrument at the ESO 3.6-m telescope. These observations were analysed with a multi-line magnetic diagnostic technique and modelled in detail with a Magnetic Doppler imaging (MDI) code. Results: We present a new set of high-precision mean longitudinal magnetic field measurements and derive a revised stellar rotational period by comparing our measurements with the literature data. We also redetermine the basic stellar atmospheric parameters. Our four Stokes parameter magnetic inversions reveal a moderately complex surface field topology with a mean field strength of 18 kG and a maximum local strength of 24 kG. A poloidal dipolar component dominates the magnetic energy spectrum of the surface field in HD 119419. However, significant contributions of the higher-order spherical harmonic components are also present. We show that the dipole plus quadrupole part of the reconstructed field geometry is incapable of reproducing the observed amplitudes and shapes of the Stokes Q and U profiles. The chemical abundance distributions of Fe, Cr, Ti, and Nd, derived self-consistently with the magnetic field geometry, are characterised by large abundance gradients and a lack of clear correlation with the magnetic field structure. Conclusions: This full Stokes vector analysis of HD 119419 extends the modern hot-star magnetic mapping investigations

  8. The determination of the rotation period and magnetic field geometry of the strongly magnetic roAp star HD 154708

    NARCIS (Netherlands)

    Hubrig, S.; Mathys, G.; Kurtz, D.W.; Schöller, M.; Elkin, V.G.; Henrichs, H.F.

    2009-01-01

    We obtained 13 spectropolarimetric observations of the strongly magnetic rapidly oscillating Ap star HD 154708 over 3 months with the multimode instrument FORS 1, installed at the 8-m Kueyen telescope of the Very Large Telescope. These observations have been used for the determination of the

  9. Whole Earth Telescope discovery of a strongly distorted quadrupole pulsation in the largest amplitude rapidly oscillating Ap star

    Science.gov (United States)

    Holdsworth, Daniel L.; Kurtz, D. W.; Saio, H.; Provencal, J. L.; Letarte, B.; Sefako, R. R.; Petit, V.; Smalley, B.; Thomsen, H.; Fletcher, C. L.

    2018-01-01

    We present a new analysis of the rapidly oscillating Ap (roAp) star, 2MASS J19400781 - 4420093 (J1940; V = 13.1). The star was discovered using SuperWASP broad-band photometry to have a frequency of 176.39 d-1 (2041.55 μHz; P = 8.2 min; Holdsworth et al. 2014a) and is shown here to have a peak-to-peak amplitude of 34 mmag. J1940 has been observed during three seasons at the South African Astronomical Observatory, and has been the target of a Whole Earth Telescope campaign. The observations reveal that J1940 pulsates in a distorted quadrupole mode with unusual pulsational phase variations. A higher signal-to-noise ratio spectrum has been obtained since J1940's first announcement, which allows us to classify the star as A7 Vp Eu(Cr). The observing campaigns presented here reveal no pulsations other than the initially detected frequency. We model the pulsation in J1940 and conclude that the pulsation is distorted by a magnetic field of strength 1.5 kG. A difference in the times of rotational maximum light and pulsation maximum suggests a significant offset between the spots and pulsation axis, as can be seen in roAp stars.

  10. 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

    . 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...... 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...... spotted magnetic variable that shows a complex rotational light variation with a period of Prot= 5.684 59 d. For the first time for any spotted magnetic star of the upper main sequence, we find clear evidence of light variation with a period of twice the rotation period, that is, a subharmonic frequency...

  11. 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 sta...

  12. A search for the age-dependency of Ap star parameters

    International Nuclear Information System (INIS)

    Ruediger, G.; Scholz, G.

    1988-01-01

    Some observational data of the sample of the magnetic chemically peculiar stars (MCP stars) are investigated statistically. For the MCP stars of spectral types later than A2 both the frequency distribution and the R · sin i-values suggest the existence of a linear relation between stellar diameter and rotation period. The MCP stars of spectral types earlier than B9 show an overpopulation of small R · sin i which may indicate the existence of a second group with smaller radius in this sample. The equatorially symmetric rotator is used as the magnetic model. With respect to its temporal behaviour the effective magnetic field is separated into dipolar and quadrupolar contribution. Both signs of the axisymmetric quadrupole moment appear with equal frequency. The dipole moment which produces the amplitude of the B eff (t) curve forms for longer periods two groups which are separated by a distinct gap. Both of the groups exhibit magnetic fields which are the stronger the greater the stellar radius is, contrary to what is expected for frozen-in fields. The dominance of magnetic curves without polarity reversal for longer-period stars is in accordance with predictions of the dynamo theory. (author)

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

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... 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.

  14. Investigation of stellar magnetic fields based on the strengths of spectral lines - Application to Omicron Pegasi and Cool AP Stars

    Science.gov (United States)

    Takeda, Yoichi

    1993-06-01

    A practical method for simultaneous determinations of H (magnetic field) and xi (microturbulence) in a stellar atmosphere is presented, which is based on the requirement that the scatter of the abundances derived from individual lines should be minimized for the best choice of H and xi. This procedure may be regarded as being an improved and extended version of the classical Hensberge-De Loore method, since it is based on a 'fine analysis' technique using a model atmosphere and the detailed Zeeman-split components of a line are explicitly taken into account with an approximate treatment of the polarization effect. This method was first applied to the hot Am star O Peg, resulting in H = 2 kG (and xi is about 1.5 km/s); this H value is fairly consistent with other estimates based either on the Stenflo-Lindegren technique or on the line-pair method. As an alternative application, surface magnetic fields of five cool Ap stars were also investigated, showing that the H-values by this method agree well with those derived from the method of differential Zeeman broadening and that the classical Hensberge-De Loore technique tends to yield somewhat underestimated values.

  15. 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

  16. SEARCHING FOR YOUNG JUPITER ANALOGS AROUND AP COL: L-BAND HIGH-CONTRAST IMAGING OF THE CLOSEST PRE-MAIN-SEQUENCE STAR

    Energy Technology Data Exchange (ETDEWEB)

    Quanz, Sascha P.; Avenhaus, Henning; Meyer, Michael R. [Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093 Zurich (Switzerland); Crepp, Justin R.; Hillenbrand, Lynne A. [Department of Astrophysics, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Janson, Markus, E-mail: quanz@astro.phys.ethz.ch [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

    2012-08-01

    The nearby M-dwarf AP Col was recently identified by Riedel et al. 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 {>=} 0.5-1 M{sub Jup} for projected separations a > 4.5 AU, and m {>=} 2 M{sub 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 {approx}>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 around M-dwarfs, gravitational microlensing studies predict that 17{sup +6}{sub -9}% of these stars host massive planets with orbital separations of 1-10 AU. Sensitive high-contrast imaging observations, like those presented here, will help to validate results from complementary detection techniques by determining the frequency of gas giant planets on wide orbits around M-dwarfs.

  17. Development and investigation of an inverse problem solution algorithm for determination of Ap stars magnetic field geometry

    International Nuclear Information System (INIS)

    Piskunov, N.E.

    1985-01-01

    Mathematical formulation of the inverse problem of determination of magnetic field geometry from the polarization profiles of spectral lines is gven. The solving algorithm is proposed. A set of model calculations has shown the effectiveness of the algorithm, the high precision of magnetic star model parameters obtained and also the advantages of the inverse problem method over the commonly used method of interpretation of effective field curves

  18. Stars

    CERN Document Server

    Hansen, Grace

    2017-01-01

    This title will cover how stars form, different types of stars, their lifecycle, and the most important star to us--the Sun! Aligned to Common Core Standards and correlated to state standards. Abdo Kids Jumbo is an imprint of Abdo Kids, a division of ABDO.

  19. Stars

    CERN Document Server

    Kukla, Lauren

    2016-01-01

    Climb Aboard! Explore planets and how they are formed! Meet key astronomers! Examine the history of mapping the stars! Investigate red giants, black and white dwarfs, neutron stars, supernovas, and black holes! See an infographic showing our solar system's statistics! Did You Know? facts and a Guidebook of the brightest stars complete your journey. Aligned to Common Core standards and correlated to state standards. Checkerboard Library is an imprint of Abdo Publishing, a division of ABDO.

  20. Got AP?

    Science.gov (United States)

    Digby, Joan

    2016-01-01

    Families, especially those considering sending their children to a private four-year university, need all the help they can get in funding college. Annmarie Guzy's essay "AP, Dual Enrollment, and the Survival of Honors Education" in this issue powerfully spells out the financial benefits that accrue from using AP courses to satisfy…

  1. Contribution à l'étude des spectres composites. VIII. HD 174016-7, une étoile Ap associée à une géante G Contribution to the study of composite spectra VIII. HD 174016-7, an Ap star with a giant G

    Science.gov (United States)

    Ginestet, N.; Griffin, R. F.; Carquillat, J. M.; Udry, S.

    1999-12-01

    HD 174016-7, listed by \\cite[Hynek (1938)]{Hynek} as a star having a composite spectrum, was on our observing programmes of such objects carried out both at the Cambridge Observatories and at the Observatoire Midi-Pyrénées. Most of the observations were made with the CORAVEL spectrovelocimeter of the Swiss telescope at the Observatoire de Haute-Provence. We find that this star is a long-period spectroscopic binary with two correlation dips; we obtain the following orbital elements: P = 3097.9 days; T = JD 2450605.2; omega = 204fdg 8; e = 0.600; K_1 = 12.95 km s-1; K_2 = 15.14 km s-1; V_0 = -1.65 km s-1; a_1 sin i = 441.1 Gm; a_2 sin i = 516.0 Gm; M_1 sin 3i = 1.967 M_sun; M_2sin 3i = 1.681 M_sun. The primary is a giant star of spectral type near G6III, and the hot dwarf secondary is found to be a peculiar A star of type A0p Sr, Cr, Eu, Si; so HD 174016-7 is, to our knowledge, the second discovered composite-spectrum binary with a Ap-type hot component. A confrontation with Hipparcos data suggests Mv_1 = 0 and m_v = 0.6 mag. On the basis of very accurate masses of main sequence stars by \\cite[Andersen (1991),]{Andersen} we estimate the mass, M_1 = 2.8 M_sun, of the giant primary, the orbital inclination, i = 63o, and the mean linear separation of the components, a = 7.2 AU. The evolutionary status of the system is discussed using \\cite[Schaller et al. (1992)]{Schaller} M_bol / T_eff diagram for stars of solar metallicity. Theoretical masses suggested by this diagram confirm the proposed model. Étude effectuée à partir d'observations faites aux Observatoires de Haute-Provence et de Cambridge.

  2. AMENABILITY OF ap (S)

    OpenAIRE

    A.M. Aminpour; Mehrdad Seilani

    2013-01-01

    In this paper, we present an important new theorem for amenability of ap(S). The set of all almost periodic functions on S is denoted by ap(S). We develop the fundamental theory of almost periodic function on a general semitopological semigroup. The principal result is that ap(S) is amenable if and only if ap(S) = Sap(S) ⊕ F0 [Theorem 3.1]. Mathematical society classification:2010 MSC. 18340

  3. 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…

  4. 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...

  5. 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

  6. APS Science 2006

    International Nuclear Information System (INIS)

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

    2007-01-01

    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 and 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

  7. 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

  8. Autoantibody profiling in APS.

    Science.gov (United States)

    Roggenbuck, D; Somma, V; Schierack, P; Borghi, M O; Meroni, P L

    2014-10-01

    The international consensus for the classification of antiphospholipid syndrome (APS) requires clinical and laboratory criteria to be considered at an equal level for diagnosing APS. Thus, detection of antiphospholipid antibodies (aPL) being a hallmark of APS has been the object of intensive investigation over the past 40 years. However, appropriate detection of aPL still remains a laboratory challenge due to their heterogeneity comprising autoantibodies reactive to different phospholipid-binding plasma proteins, such as beta-2 glycoprotein I (β2GPI) and prothrombin. The relevance of aPL interacting with phospholipids other than cardiolipin (CL, diphosphatidylglycerol), such as phosphatidylserine (PS), remains elusive with regard to the diagnosis of APS. Recently, the concept of aPL profiling has been introduced to assess the risk of thrombotic complications in patients with APS. New assay techniques, apart from enzyme-linked immunosorbent assays (ELISAs) recommended by the international consensus for the classification of APS, have been proposed for multiplexing of aPL testing. Line immunoassays (LIAs) employing a novel hydrophobic solid phase for the simultaneous detection of different aPL seem to be an intriguing alternative. We evaluated a novel multiplex LIA employing a hydrophobic membrane coated with different phospholipid (PL)-binding proteins or PLs. The performance characteristics of this new multiplexing assay technique demonstrated its usefulness for aPL profiling. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  9. 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

  10. APS SCIENCE 2016

    Energy Technology Data Exchange (ETDEWEB)

    Fenner, Richard B. [Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)

    2017-05-01

    The Advanced Photon Source (APS) occupies an 80-acre site on the Argonne national laboratory campus, about 25 miles from downtown chicago, illinois. it shares the site with the center for nanoscale materials and the Advanced Protein characterization facility. for directions to Argonne, see http://www.anl.gov/directions-and-visitor-information. The APS, a national synchrotron radiation research facility operated by Argonne for the u.S. department of energy (doe) office of Science, provides this nation’s brightest high-energy x-ray beams for science. research by APS users extends from the center of the earth to outer space, from new information on combustion engines and microcircuits to new drugs and nanotechnologies whose scale is measured in billionths of a meter. The APS helps researchers illuminate answers to the challenges of our high-tech world, from developing new forms of energy, to sustaining our nation’s technological and economic competitiveness, to pushing back against the ravages of disease. research at the APS promises to have far-reaching

  11. APS power supply controls

    International Nuclear Information System (INIS)

    Saunders, C.W.; Despe, O.D.

    1994-01-01

    The purpose of this document is to provide comprehensive coverage of the APS power supply control design. This includes application software, embedded controller software, networks, and hardware. The basic components will be introduced first, followed by the requirements driving the overall design. Subsequent sections will address each component of the design one by one. Latter sections will address specific applications

  12. Star point centroid algorithm based on background forecast

    Science.gov (United States)

    Wang, Jin; Zhao, Rujin; Zhu, Nan

    2014-09-01

    The calculation of star point centroid is a key step of improving star tracker measuring error. A star map photoed by APS detector includes several noises which have a great impact on veracity of calculation of star point centroid. Through analysis of characteristic of star map noise, an algorithm of calculation of star point centroid based on background forecast is presented in this paper. The experiment proves the validity of the algorithm. Comparing with classic algorithm, this algorithm not only improves veracity of calculation of star point centroid, but also does not need calibration data memory. This algorithm is applied successfully in a certain star tracker.

  13. APS Science 2007

    International Nuclear Information System (INIS)

    2008-01-01

    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

  14. 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.

  15. Renal involvement in the antiphospholipid syndrome (APS)-APS nephropathy.

    Science.gov (United States)

    Tektonidou, Maria G

    2009-06-01

    Although the kidney represents a major target organ in antiphospholipid syndrome (APS), renal involvement in APS was poorly recognized until recently. The most well-recognized renal manifestations of APS are the renal artery thrombosis/stenosis, renal infarction, hypertension, renal vein thrombosis, end-stage renal disease, increased allograft vascular thrombosis, some types of glomerular disease, and a small-vessel vaso-occlusive nephropathy, recently defined as APS nephropathy. APS nephropathy was first described in primary APS patients, characterized by acute thrombotic lesions in glomeruli and/or arterioles (thrombotic microangiopathy) and chronic vascular lesions such as fibrous intimal hyperplasia of arterioles and interlobular arteries, organized thrombi with or without recanalization, and fibrous arterial and arteriolar occlusions or focal cortical atrophy. APS nephropathy was also detected in further studies including patients with systemic lupus erythematosus (SLE)-related APS and SLE/non-APS patients with positive antiphospholipid antibodies, independently of lupus nephritis. The same histologic lesions, especially thrombotic mictroangiopathy, were also observed in patients with catastrophic APS. The most frequent clinical and laboratory characteristics of APS nephropathy in all the above groups of patients are hypertension (often severe), proteinuria (ranging from mild to nephrotic range), hematuria, and acute or chronic renal insufficiency.

  16. Which of Kepler's Stars Flare?

    Science.gov (United States)

    Kohler, Susanna

    2017-12-01

    function of Rossby number, which traces stellar rotation. Higher rotation rates correspond to lower Rossby numbers, so these data indicate that more rapidly rotating stars are more likely to exhibit flares. [Van Doorsselaere et al. 2017]Roughly 3.5% of Kepler stars in this sample are flaring stars.24 new A stars are found to show flaring activity. This is interesting because A stars arent thought to have an outer convective zone, which should prevent a magnetic dynamo from operating. Yet these flaring-star detections add to the body of evidence that at least some A stars do show magnetic activity.Most flaring stars in the sample are main-sequence stars, but 653 giants were found to have flaring activity. As with A stars, its unexpected that giant stars would have strong magnetic fields their increase in size and gradual spin-down over time should result in weakening of the surface fields. Nevertheless, it seems that the flare incidence of giant stars is similar to that of F or G main-sequence stars.All stellar types appear to have a small fraction of flare stars stars with an especially high rate of flare occurrence.Rapidly rotating stars are more likely to flare, tend to flare more often, and tend to have stronger flares than slowly rotating stars.As a next step, the authors plan to apply their flare detection algorithm to the larger sample of all Kepler data. In the meantime, this study has both deepened a few mysteries and moved us a step closer in our understanding of which stars flare and why.CitationTom Van Doorsselaere et al 2017 ApJS 232 26. doi:10.3847/1538-4365/aa8f9a

  17. 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....

  18. Thrombotic risk assessment in APS: the Global APS Score (GAPSS).

    Science.gov (United States)

    Sciascia, S; Bertolaccini, M L

    2014-10-01

    Recently, we developed a risk score for antiphospholipid syndrome (APS) (Global APS Score or GAPSS). This score derived from the combination of independent risk factors for thrombosis and pregnancy loss, taking into account the antiphospholipid antibodies (aPL) profile (criteria and non-criteria aPL), the conventional cardiovascular risk factors, and the autoimmune antibodies profile. We demonstrate that risk profile in APS can be successfully assessed, suggesting that GAPSS can be a potential quantitative marker of APS-related clinical manifestations. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  19. Westinghouse AP1000 licensing maturity

    International Nuclear Information System (INIS)

    Schulz, T.; Vijuk, R.P.

    2005-01-01

    The Westinghouse AP1000 Program is aimed at making available a nuclear power plant that is economical in the U.S deregulated electrical power industry in the near-term. The AP1000 is two-loop 1000 MWe pressurizer water reactor (PWR). It is an up rated version of the AP600. The AP1000 uses passive safety systems to provide significant and measurable improvements in plant simplification, safety, reliability, investment protection and plant costs. The AP1000 uses proven technology, which builds on over 35 years of operating PWR experience. The AP1000 received Final Design Approval by the United States Nuclear Regulatory Commission (U.S. NRC) in September 2004. The AP1000 meets the US utility requirements. The AP1000 and its sister plant the AP600 have gone through a very through and complete licensing review. This paper describes the U.S. NRC review efforts of both the AP600 and the AP1000. The detail of the review and the independent calculations, evaluations and testing is discussed. The AP600 licensing documentation was submitted in 1992. The U.S. NRC granted Final Design Approval in 1999. During the intervening 7 years, the U.S. NRC asked thousands of questions, performed independent safety analysis, audited Westinghouse calculations and analysis, and performed independent testing. The more significant areas of discussion will be described. For the AP1000 Westinghouse first engaged the U.S. NRC in pre-certification discussions to define the extent of the review required, since the design is so similar to the AP600. The AP1000 licensing documentation was submitted in March 2002. The U.S. NRC granted Final Design Approval in September 2004. During the intervening 2 1/2 years, the U.S. NRC asked hundreds of questions, performed independent safety analysis, audited Westinghouse calculations and analysis, and performed independent testing. The more significant areas of discussion will be described. The implications of this review and approval on AP1000 applications in

  20. 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...

  1. AP1000 Design for Security

    International Nuclear Information System (INIS)

    Long, L.B.; Cummins, W.E.; Winters, J.W.

    2006-01-01

    Nuclear power plants are protected from potential security threats through a combination of robust structures around the primary system and other vital equipment, security systems and equipment, and defensive strategy. The overall objective for nuclear power plant security is to protect public health and safety by ensuring that attacks or sabotage do not challenge the ability to safely shutdown the plant or protect from radiological releases. In addition, plants have systems, features and operational strategies to cope with external conditions, such as loss of offsite power, which could be created as part of an attack. Westinghouse considered potential security threats during design of the AP1000 PWR. The differences in plant configuration, safety system design, and safe shutdown equipment between existing plants and AP1000 affect potential vulnerabilities. This paper provides an evaluation of AP1000 with respect to vulnerabilities to security threats. The AP1000 design differs from the design of operating PWRs in the US in the configuration and the functional requirements for safety systems. These differences are intentional departures from conventional PWR designs which simplify plant design and enhance overall safety. The differences between the AP1000 PWR and conventional PWRs can impact vulnerabilities to security threats. The NRC addressed security concerns as part of their reviews for AP1000 Design Certification, and did not identify any security issues of concern. However, much of the detailed security design information for the AP1000 was deferred to the combined Construction and Operating License (COL) phase as many of the security issues are site-specific. Therefore, NRC review of security issues related to the AP1000 is not necessarily complete. Further, since the AP1000 plant design differs from existing PWRs, it is not obvious that the analyses and assessments prepared for existing plants also apply to the AP1000. We conclude that, overall, the AP1000

  2. AP1000. The PWR revisited

    International Nuclear Information System (INIS)

    The distinguishing features of Westinghouse's AP1000 advanced passive pressurized water reactor are highlighted. In particular, the AP1000's passive safety features are described as well as their implications for simplifying the design, construction, and operation of this design compared to currently operating plants, and significantly increasing safety margins over current plants as well. The AP1000 design specifically incorporates the knowledge acquired from the substantial accumulation of power reactor operating experience and benefits from the application of the Probabilistic Risk Assessment in the design process itself. The AP1000 design has been certified by the US Nuclear Regulatory Commission under its new rules for licensing new nuclear plants, 10 CFR Part 52, and is the subject of six combined Construction and Operating License applications now being developed. Currently the AP1000 design is being assessed against the EUR Rev C requirements for new nuclear power plants in Europe. (author)

  3. 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....

  4. Molecular Star

    Indian Academy of Sciences (India)

    This report describes the making of a self-assembled coordination architecture that is named as a 'molecular star' since it resembles the shape of a star; more specifically a five-pointed star. This work has been already published in Chemistry- A European Jour- nal in the September 2017 issue and was featured in the cover.

  5. Asteroseismic Theory of Rapidly Oscillating Ap Stars Margarida S ...

    Indian Academy of Sciences (India)

    If we were to neglect the effect of the Coriolis force, then the problem would be invariant under the transformation m → −m. Thus, the coefficients of the terms Y1. 1 and Y−1. 1 in the linear combinations that define the angular part of the eigen- functions would necessarily have the same absolute value. In fact, if there were no.

  6. A Search for Variability in Ap and Am Stars

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Since January 2016, the Journal of Astrophysics and Astronomy has moved to Continuous Article Publishing (CAP) mode. This means that each accepted article is being published immediately online with DOI and article citation ID with starting page number 1. Articles are also visible in Web of Science ...

  7. Collapsing Enormous Stars

    Science.gov (United States)

    Kohler, Susanna

    2015-09-01

    be proportional to the free-fall timescale of the collapsing star, the collapse of these supermassive stars would create much longer GRBs than are typical of massive stars today. Instead of the typical long-GRB length of ~30 seconds, these ultra-long GRBs would be 104106 seconds.Interestingly, we have already detected a small number of ultralong GRBs; they make up the tail end of the long GRB duration distribution. Could these detections be signals of collapsing supermassive stars in the early universe? According to the authors estimates, we could optimistically expect to detect roughly one of these events per year so its entirely possible!CitationTatsuya Matsumoto et al 2015 ApJ 810 64. doi:10.1088/0004-637X/810/1/64

  8. Meet the APS Editors Reception

    Science.gov (United States)

    2014-03-01

    The APS Journal Editors invite you to join them for conversation and light refreshments. The Editors will be available to answer questions, discuss your ideas, and listen to your comments about the journals. All are welcome to attend.

  9. AP1000TM plant modularization

    International Nuclear Information System (INIS)

    Cantarero L, C.; Demetri, K. J.; Quintero C, F. P.

    2016-09-01

    The AP1000 TM plant is an 1100 M We pressurized water reactor (PWR) with passive safety features and extensive plant simplifications that enhance construction, operation, maintenance and safety. Modules are used extensively in the design of the AP1000 plant nuclear island. The AP1000 plant uses modern, modular-construction techniques for plant construction. The design incorporates vendor-designed skids and equipment packages, as well as large, multi-ton structural modules and special equipment modules. Modularization allows traditionally sequential construction tasks to be completed simultaneously. Factory-built modules can be installed at the site in a planned construction schedule. The modularized AP1000 plant allows many more construction activities to proceed in parallel. This reduces plant construction calendar time, thus lowering the costs of plant financing. Furthermore, performing less work onsite significantly reduces the amount of skilled field-craft labor, which costs more than shop labor. In addition to labor cost savings, doing more welding and fabrication in a factory environment raises the quality of work, allowing more scheduling flexibility and reducing the amount of specialized tools required onsite. The site layout for the AP1000 plant has been established to support modular construction and efficient operations during construction. The plant layout is compact, using less space than previous conventional plant layouts. This paper provides and overview of the AP1000 plant modules with an emphasis on structural modules. Currently the Westinghouse AP1000 plant has four units under construction in China and four units under construction in the United States. All have shown successful fabrication and installation of various AP1000 plant modules. (Author)

  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. Star Wreck

    CERN Document Server

    Kusenko, A; Tinyakov, Peter G; Tkachev, Igor I; Kusenko, Alexander; Shaposhnikov, Mikhail; 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 origin of the gamma-ray bursts.

  12. The Nainital-Cape Survey: contributions to asteroseismology of CP stars

    Science.gov (United States)

    Joshi, S.; Girish, V.; Martinez, P.; Kurtz, D. W.; Sagar, R.; Seetha, S.; Mary, D. L.; Ashoka, B. N.

    2007-06-01

    We present a progress report on the Nainital-Cape Survey. Pulsations of the δ Scuti type have been discovered in the chemically peculiar A-type stars HD 13038, HD 13079, HD 98851, HD 102480, HD 113878 and HD 118660. HD 12098 has been discovered to be a roAp star. We have also detected evidence for roAp-like 6.1-minute oscillations in the Am star HD 207561.

  13. 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.

  14. [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.

  15. Star Polymers.

    Science.gov (United States)

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

    2016-06-22

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

  16. 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....

  17. 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....

  18. AP Human Geography and Success on the AP Test

    Science.gov (United States)

    Roncone, John; Newhalfen, Nate

    2013-01-01

    Classroom projects that explore culture and globalization enhance the curriculum and help students see how geography directly connects to their lives. These authors contend that a project-based approach can supplement the teaching of an AP Human Geography course, and visualize this course as an essential tool for students to truly understand how…

  19. The Fate of Merging Neutron Stars

    Science.gov (United States)

    Kohler, Susanna

    2017-08-01

    state. They then combined this information with Monte Carlo simulations based on the mass distribution of neutron-star binaries in our galaxy. From these simulations, Piro and collaborators could predict the distribution of fates expected for merging neutron-star binaries, given different equations of state.The authors found that the fate of the merger could vary greatly depending on the equation of state you assume. Intriguingly, all equations of state resulted in a surprisingly high fraction of systems that merged to form a neutron star or a supramassive neutron star in fact, four out of the five equations of state predicted that 80100% of systems would result in a neutron star or a supermassive neutron star.Lessons from ObservationsThe frequency bands covered by various current and planned gravitational wave observatories. Advanced LIGO has the right frequency coverage to be able to explore a neutron-star remnant if the signal is loud enough. [Christopher Moore, Robert Cole and Christopher Berry]These results have important implications for our future observations. The high predicted fraction of neutron stars resulting from these mergers tells us that its especially important for gravitational-wave observatories to probe 14 kHz emission. This frequency range will enable us to study the post-merger neutron-star or supramassive-neutron-star remnants.Even if we cant observe the remnants behavior after it forms, we can still compare the distribution of remnants that we observe in the future to the predictions made by Piro and collaborators. This will potentially allow us to constrain the neutron-star equation of state, revealing the physics of neutron-star interiors even without direct observations.CitationAnthony L. Piro et al 2017 ApJL 844 L19. doi:10.3847/2041-8213/aa7f2f

  20. Dark stars

    DEFF Research Database (Denmark)

    Maselli, Andrea; Pnigouras, Pantelis; Nielsen, Niklas Grønlund

    2017-01-01

    to the formation of compact objects predominantly made of dark matter. Considering both fermionic and bosonic (scalar φ4) equations of state, we construct the equilibrium structure of rotating dark stars, focusing on their bulk properties and comparing them with baryonic neutron stars. We also show that these dark...... objects admit the I-Love-Q universal relations, which link their moments of inertia, tidal deformabilities, and quadrupole moments. Finally, we prove that stars built with a dark matter equation of state are not compact enough to mimic black holes in general relativity, thus making them distinguishable...

  1. APS beamline standard components handbook

    Energy Technology Data Exchange (ETDEWEB)

    Kuzay, T.M.

    1992-01-01

    It is clear that most Advanced Photon Source (APS) Collaborative Access Team (CAT) members would like to concentrate on designing specialized equipment related to their scientific programs rather than on routine or standard beamline components. Thus, an effort is in progress at the APS to identify standard and modular components of APS beamlines. Identifying standard components is a nontrivial task because these components should support diverse beamline objectives. To assist with this effort, the APS has obtained advice and help from a Beamline Standardization and Modularization Committee consisting of experts in beamline design, construction, and operation. The staff of the Experimental Facilities Division identified various components thought to be standard items for beamlines, regardless of the specific scientific objective of a particular beamline. A generic beamline layout formed the basis for this identification. This layout is based on a double-crystal monochromator as the first optical element, with the possibility of other elements to follow. Pre-engineering designs were then made of the identified standard components. The Beamline Standardization and Modularization Committee has reviewed these designs and provided very useful input regarding the specifications of these components. We realize that there will be other configurations that may require special or modified components. This Handbook in its current version (1.1) contains descriptions, specifications, and pre-engineering design drawings of these standard components. In the future, the APS plans to add engineering drawings of identified standard beamline components. Use of standard components should result in major cost reductions for CATs in the areas of beamline design and construction.

  2. APS beamline standard components handbook

    International Nuclear Information System (INIS)

    Kuzay, T.M.

    1992-01-01

    It is clear that most Advanced Photon Source (APS) Collaborative Access Team (CAT) members would like to concentrate on designing specialized equipment related to their scientific programs rather than on routine or standard beamline components. Thus, an effort is in progress at the APS to identify standard and modular components of APS beamlines. Identifying standard components is a nontrivial task because these components should support diverse beamline objectives. To assist with this effort, the APS has obtained advice and help from a Beamline Standardization and Modularization Committee consisting of experts in beamline design, construction, and operation. The staff of the Experimental Facilities Division identified various components thought to be standard items for beamlines, regardless of the specific scientific objective of a particular beamline. A generic beamline layout formed the basis for this identification. This layout is based on a double-crystal monochromator as the first optical element, with the possibility of other elements to follow. Pre-engineering designs were then made of the identified standard components. The Beamline Standardization and Modularization Committee has reviewed these designs and provided very useful input regarding the specifications of these components. We realize that there will be other configurations that may require special or modified components. This Handbook in its current version (1.1) contains descriptions, specifications, and pre-engineering design drawings of these standard components. In the future, the APS plans to add engineering drawings of identified standard beamline components. Use of standard components should result in major cost reductions for CATs in the areas of beamline design and construction

  3. Star formation

    International Nuclear Information System (INIS)

    Woodward, P.R.

    1978-01-01

    Theoretical models of star formation are discussed beginning with the earliest stages and ending in the formation of rotating, self-gravitating disks or rings. First a model of the implosion of very diffuse gas clouds is presented which relies upon a shock at the edge of a galactic spiral arm to drive the implosion. Second, models are presented for the formation of a second generation of massive stars in such a cloud once a first generation has formed. These models rely on the ionizing radiation from massive stars or on the supernova shocks produced when these stars explode. Finally, calculations of the gravitational collapse of rotating clouds are discussed with special focus on the question of whether rotating disks or rings are the result of such a collapse. 65 references

  4. Carbon Stars

    Indian Academy of Sciences (India)

    Abstract. 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.

  5. Star formation

    Energy Technology Data Exchange (ETDEWEB)

    Woodward, P.R.

    1978-09-27

    Theoretical models of star formation are discussed beginning with the earliest stages and ending in the formation of rotating, self-gravitating disks or rings. First a model of the implosion of very diffuse gas clouds is presented which relies upon a shock at the edge of a galactic spiral arm to drive the implosion. Second, models are presented for the formation of a second generation of massive stars in such a cloud once a first generation has formed. These models rely on the ionizing radiation from massive stars or on the supernova shocks produced when these stars explode. Finally, calculations of the gravitational collapse of rotating clouds are discussed with special focus on the question of whether rotating disks or rings are the result of such a collapse. 65 references.

  6. Radiation effects on active pixel sensors (APS)

    International Nuclear Information System (INIS)

    Cohen, M.; David, J.P.

    1999-01-01

    Active pixel sensor (APS) is a new generation of image sensors which presents several advantages relatively to charge coupled devices (CCDs) particularly for space applications (APS requires only 1 voltage to operate which reduces considerably current consumption). Irradiation was performed using 60 Co gamma radiation at room temperature and at a dose rate of 150 Gy(Si)/h. 2 types of APS have been tested: photodiode-APS and photoMOS-APS. The results show that photoMOS-APS is more sensitive to radiation effects than photodiode-APS. Important parameters of image sensors like dark currents increase sharply with dose levels. Nevertheless photodiode-APS sensitivity is one hundred time lower than photoMOS-APS sensitivity

  7. 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....

  8. 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....

  9. 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.…

  10. Molecular evolution of the AP2 subfamily.

    Science.gov (United States)

    Shigyo, Mikao; Hasebe, Mitsuyasu; Ito, Motomi

    2006-02-01

    The AP2 (APETALA2)/EREBP (Ethylene Responsive Element Binding Protein) multigene family includes developmentally and physiologically important transcription factors. AP2/EREBP genes are divided into two subfamilies: AP2 genes with two AP2 domains and EREBP genes with a single AP2/ERF (Ethylene Responsive Element Binding Factor) domain. Based on previous phylogenetic analyses, AP2 genes can be divided into two clades, AP2 and ANT groups. To clarify the molecular evolution of the AP2 subfamily, we isolated and sequenced genes with two AP2 domains from three gymnosperms, Cycas revoluta, Ginkgo biloba, and Gnetum parvifolium,as well as from the moss Physcomitrella patens. Expressions of AP2-like genes, including AP2, in Arabidopsis thaliana are regulated by the microRNA miR172. We found that the target site of miR172 is significantly conserved in gymnosperm AP2 homologs, suggesting that regulatory mechanisms of gene expression using microRNA have been conserved over the three hundred million years since the divergence of gymnosperm and flowering plant lineages. We inferred a phylogenetic relationship of these genes with the green alga Chlamydomonas reinhardtii and seed-plant genes available in public DNA databases. The phylogenetic tree showed that the AP2 subfamily diverged into the AP2 and ANT groups before the last common ancestor of land plants and after C. reinhardtii diverged from the land-plant lineage. The tree also indicated that each AP2 and ANT group further diverged into several clades through gene duplications prior to the divergence of gymnosperms and angiosperms.

  11. Fellow's Apéro

    CERN Document Server

    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

  12. 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....

  13. Spectroscopy of λ Bootis stars

    International Nuclear Information System (INIS)

    Heiter, U.

    2000-05-01

    theory picture. In the last part of the thesis, the λ Bootis abundance pattern is compared to that of related groups of chemically peculiar stars, i.e. classical CP stars (He-weak, Am and Ap), metal poor stars (field horizontal branch, field blue straggler, and F type main sequence stars), and stars with circumstellar material (post-AGB, Vega-like and A shell stars). A sample of five metal poor post-AGB stars, for which the log g values are much lower than for the λ Bootis stars, shows an abundance pattern similar to that of the λ Bootis stars, but with larger underabundances. All other groups can be well distinguished from the λ Bootis stars on the basis of their element abundance. (author)

  14. Hybrid stars

    Indian Academy of Sciences (India)

    physics pp. 753-756. Hybrid stars. AsHOK GOYAL. Department of Physics and Astrophysics, University of Delhi, Delhi 110 007, India. Abstract. Recently there have been important developments in the determination of neutron ... be composed of normal nuclear matter with hyperons and/or condensed mesons. The matter at ...

  15. Star Conquest

    OpenAIRE

    Porrino Serrano, Fernando

    2014-01-01

    Star Conquest es un juego de mesa "print n play" de estrategia por turnos para dos o tres jugadores. Éste proyecto consiste en tomar el juego de mesa original y desarrollar una adaptación en forma de videojuego para distintas plataformas

  16. Hybrid stars

    Indian Academy of Sciences (India)

    Hybrid stars. AsHOK GOYAL. Department of Physics and Astrophysics, University of Delhi, Delhi 110 007, India. Abstract. Recently there have been important developments in the determination of neutron ... number and the electric charge. ... available to the system to rearrange concentration of charges for a given fraction of.

  17. 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.

  18. Carbon stars

    International Nuclear Information System (INIS)

    Azzopardi, M.; Lequeux, J.; Rebeirot, E.

    1985-01-01

    Several stars of this type have just been detected in galaxies where they were not suspected and where they reveal a recent activity not really corresponding to current ideas. Data given by these observations allow the astrophysicists to improve the galaxy evolution models, in particular the evolution model of our galaxy [fr

  19. APS high heat load monochromator

    International Nuclear Information System (INIS)

    Lee, W.K.; Mills, D.

    1993-02-01

    This document contains the design specifications of the APS high heat load (HHL) monochromator and associated accessories as of February 1993. It should be noted that work is continuing on many parts of the monochromator including the mechanical design, crystal cooling designs, etc. Where appropriate, we have tried to add supporting documentation, references to published papers, and calculations from which we based our decisions. The underlying philosophy behind performance specifications of this monochromator was to fabricate a device that would be useful to as many APS users as possible, that is, the design should be as generic as possible. In other words, we believe that this design will be capable of operating on both bending magnet and ID beamlines (with the appropriate changes to the cooling and crystals) with both flat and inclined crystal geometries and with a variety of coolants. It was strongly felt that this monochromator should have good energy scanning capabilities over the classical energy range of about 4 to 20 keywith Si (111) crystals. For this reason, a design incorporating one rotation stage to drive both the first and second crystals was considered most promising. Separate rotary stages for the first and second crystals can sometimes provide more flexibility in their capacities to carry heavy loads (for heavily cooled first crystals or sagittal benders of second crystals), but their tuning capabilities were considered inferior to the single axis approach

  20. APS high heat load monochromator

    Energy Technology Data Exchange (ETDEWEB)

    Lee, W.K.; Mills, D.

    1993-02-01

    This document contains the design specifications of the APS high heat load (HHL) monochromator and associated accessories as of February 1993. It should be noted that work is continuing on many parts of the monochromator including the mechanical design, crystal cooling designs, etc. Where appropriate, we have tried to add supporting documentation, references to published papers, and calculations from which we based our decisions. The underlying philosophy behind performance specifications of this monochromator was to fabricate a device that would be useful to as many APS users as possible, that is, the design should be as generic as possible. In other words, we believe that this design will be capable of operating on both bending magnet and ID beamlines (with the appropriate changes to the cooling and crystals) with both flat and inclined crystal geometries and with a variety of coolants. It was strongly felt that this monochromator should have good energy scanning capabilities over the classical energy range of about 4 to 20 keywith Si (111) crystals. For this reason, a design incorporating one rotation stage to drive both the first and second crystals was considered most promising. Separate rotary stages for the first and second crystals can sometimes provide more flexibility in their capacities to carry heavy loads (for heavily cooled first crystals or sagittal benders of second crystals), but their tuning capabilities were considered inferior to the single axis approach.

  1. Star Products and Applications

    OpenAIRE

    Iida, Mari; Yoshioka, Akira

    2010-01-01

    Star products parametrized by complex matrices are defined. Especially commutative associative star products are treated, and star exponentials with respect to these star products are considered. Jacobi's theta functions are given as infinite sums of star exponentials. As application, several concrete identities are obtained by properties of the star exponentials.

  2. Velocity Distributions of Runaway Stars Produced by Supernovae in ...

    Indian Academy of Sciences (India)

    Brown, W. R., Anderson, J., Gnedin, O. Y., Bond, H. E., Geller, M. J., Kenyon, S. J. 2015,. ApJ, 804, 49. Brown, W. R., Geller, M. J., Kenyon, S. J., Kurtz, M. J. 2006, ApJ, 647, 303. Eggleton, P. P. 1993, in: Astronomical Society of the Pacific Conference Series, Vol. 45,. Luminous High-Latitude Stars, edited by D. D. Sasselov, ...

  3. Submitting to the APS Journals

    Science.gov (United States)

    Hall, Donavan; Johnson, Brant; Kim-Zajonz, Julie; Ucko, Daniel

    2006-03-01

    This session will contain a short presentation of policies, practices and general advice for authors submitting to APS journals. For both the Physical Review and Physical Review Letters, it will focus on such things as the importance of a properly written introduction; our current drive for increased accessibility in the Phys. Rev. journals; how a well written cover letter and how suggesting referees will aid your manuscript in the review process. We shall also discuss responding to referees and offer advice on resubmitting your manuscript. In addition there will be information on technical details such as web submission and the Author Status Information Service (ASIS). The presentation will then be followed by a moderated panel discussion, where editors from PRL, PRB and PRE will answer questions from the audience on author issues.

  4. APS: Lighting up the future

    International Nuclear Information System (INIS)

    Potent, V.J.

    1993-01-01

    Work on the Advanced Photon Source (APS) at Argonne National Laboratory (ANL) involves the construction and supporting research and development for a national user facility for synchrotron radiation research in the x-ray region. The facility, when operational in 1997, will provide super-intense x-ray beams for many areas of basic research and will serve the entire US x-ray research community of several thousand users. This paper describes the pertinent features of the design, construction and planned operation of the facility; and the impact quality has had in these areas. In addition, the introduction of several quality management techniques such as total quality management, reliability/availability planning, and user interface are discussed concerning their status and success

  5. 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....

  6. Strangeon Stars

    Science.gov (United States)

    Lu, Jiguang; Xu, Renxin

    Stable micro-nucleus is 2-flavored (u and d), whereas stable macro-nucleus could be 3-flavored (u, d, and s) if the light flavor symmetry restores there. Nucleons are the constituent of a nucleus, while strangeons are named as the constituent of 3-flavored baryonic matter. Gravity-compressed baryonic object created after core-collapse supernova could be strangeon star if the energy scale (˜0.5 GeV) cannot be high enough for quark deconfinement and if there occurs 3-flavor symmetry restoration. Strangeon stars are explained here, including their formation and manifestation/identification. Much work, coupled with effective micro-model of strangeon matter, is needed to take advantage of the unique opportunities advanced facilities will provide.

  7. Another Possibility for Boyajian's Star

    Science.gov (United States)

    Kohler, Susanna

    2017-07-01

    2017]Foukal recognized that this phenomenon may also provide an explanation for Boyajians star. He modeled how this might occur for Boyajians star, demonstrating that if its flux is somehow blocked from reaching the surface and stored in a shallow convective zone, this can account for the 20% dips seen in the stars light curve.In addition, these sporadic flux-blocking events would cause Boyajians star to constantly be relaxing from the post-blockage enhanced luminosity. This decay which occurs at rates of 0.11% brightness per year for convective-zone depths of tens of thousands of kilometers would nicely account for the long-term, gradual dimming observed.Whats blocking the flux? Foukal postulates a few options, including magnetic activity (as with the Sun), differential rotation, sporadic changes in photospheric abundances, and simply random variation in convective efficiency.Strangely UniqueBoyajians stars flux in May and June shows some brand new dips. Note that the team now names them! [Tabetha Boyajian and team]So why have we only found one star with light curves like Boyajians? If these are inherently natural processes in the star, we would expect to have seen more than one such object. This may be selection effect Boyajians star lies at the hot end of the range of stars that Kepler observes or it may be that the star is reaching the end of its convective lifetime.Until we discover more cases, the best we can hope for is more data from Boyajians star itself. Conveniently, it has continued to keep us on our toes, with new dips in May and June. Perhaps our continued observations will finally reveal the answer to this mystery.CitationPeter Foukal 2017 ApJL 842 L3. doi:10.3847/2041-8213/aa740f

  8. 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

  9. [Type 2 autoimmune polyendocrine syndromes (APS-2)].

    Science.gov (United States)

    Vialettes, Bernard; Dubois-Leonardon, Noémie

    2013-01-01

    Type 2 autoimmune polyendocrine syndromes (APS-2) are the most frequent disorders associating several organ-specific autoimmune diseases. Their high prevalence is due to the fact that the main manifestations of APS-2, such as thyroidal autoimmunity, type 1 diabetes, autoimmune gastric atrophy and vitiligo, are common diseases. APS-2 represents a clinical model that can serve to help unravel the mechanisms underlying autoimmunity. Diagnosis of APS-2 is a challenge for the clinician, especially in poorly symptomatic forms, and may require systematic screening based on measurement of autoantibodies and functional markers.

  10. Consumo de antimicrobianos en APS

    Directory of Open Access Journals (Sweden)

    María Cristina Lara Bastanzuri

    2003-08-01

    Full Text Available Con el propósito de describir el patrón de uso de los medicamentos para el tratamiento con antimicrobianos en APS en Cuba en el período de 1989 al 2000, se diseñó un estudio descriptivo, observacional y retrospectivo clasificado dentro de los estudios de utilización de medicamentos como de consumo. Para ello se calcularon las dosis diarias definidas cada día de determinado fármaco de los grupos clasificados según ATC como tetraciclinas, anfenicoles, penicilinas de amplio espectro, cefalosporinas, sulfonamidas y trimetoprim, macrólidos, estreptomicinas y quinolonas. Además, se tomaron las cifras de pacientes inscriptos a penicilina benzatínica y se comparó con la población expuesta obtenida a partir de las DHD. Las penicilinas son las de mayor consumo con tendencia al aumento, igual que los aminoglucósidos, mientras que la tetraciclina presenta cifras mayores de DHD. La tendencia del cloranfenicol es a disminuir. La población expuesta está muy por debajo de los pacientes inscriptos en penicilina benzatínica y las líneas de tendencia no son similares. Excepto la docixiclina, el resto de los antimicrobianos recomendados en la Guía Terapéutica para APS se encuentran en el Listado Básico de Medicamentos del país para el nivel primario de atención médica.With the objective of describing the pattern of drug use in antimicrobial-based treatment in the primary health care in Cuba from 1989 to 2000, we designed a retrospective descriptive and observational study, classified into the study of drug use as consumption. To this end, the daily doses of certain drugs from the ATC-classified groups were calculated, which included tetracycline, amphenicols, broad spectrum penicilins, cephalosporins, sulfonamides, trimethoprim, macrolides, streptomycin and quinolones. Also, the number of patients registered as benzathine peniciline consumers was taken and compared to the exposed population data obtained from the DHD. Penicillins are the

  11. A Binary Nature of the Marginal CP Star Sigma Sculptoris

    Science.gov (United States)

    Janík, Jan; Krtička, Jiří; Mikulášek, Zdeněk; Zverko, Juraj; Pintado, Olga; Paunzen, Ernst; Prvák, Milan; Skalický, Jan; Zejda, Miloslav; Adam, Christian

    2018-05-01

    The A2 V star σ Scl was suspected of being a low-amplitude rotating variable of the Ap-type star by several authors. Aiming to decide whether the star is a variable chemically peculiar (CP) star, we searched for the photometric and spectroscopic variability, and determined chemical abundances of σ Scl. The possible variability was tested using several types of periodograms applied to the photometry from Long-Term Photometry of Variables project (LTPV) and Hipparcos. Sixty spectrograms of high signal-to-noise (S/N) were obtained and used for chemical analysis of the stellar atmosphere and for looking for spectral variability that is symptomatic for the CP stars. We did not find any signs of the light variability or prominent chemical peculiarity, that is specific for the CP stars. The only exception is the abundance of scandium, which is significantly lower than the solar one and yttrium and barium, which are strongly overabundant. As a by-product of the analysis, and with the addition of 29 further spectra, we found that σ Scl is a single-lined spectroscopic binary with orbital period of 46.877(8) d. We argue that σ Scl is not an Ap star, but rather a marginal Am star in SB1 system. The spectral energy distribution of the binary reveals infrared excess due to circumstellar material.

  12. Unusual Metals in Galactic Center Stars

    Science.gov (United States)

    Hensley, Kerry

    2018-03-01

    while one star is only slightly above solar metallicity, the other is likely more than four times as metal-rich as the Sun.The features in the observed and synthetic spectra generally matched well, but the absorption lines of scandium, vanadium, and yttrium were consistently stronger in the observed spectra than in the synthetic spectra. This led the authors to conclude that these galactic center stars are unusually rich in these metals trace elements that could reveal the formation history of the galactic nucleus.Old Stars, New Trends?Scandium to iron ratio versusiron abundance for stars in the disk of the Milky Way (blue) and the stars in this sample (orange). The value reported for this sample is a 95% lower limit. [Do et al. 2018]For stars in the disk of the Milky Way, the abundance of scandium relative to iron tends to decrease as the overall metallicity increases, but the stars investigated in this study are both iron-rich and anomalously high in scandium. This hints that the nuclear star cluster might represent a distinct stellar population with different metallicity trends.However, its not yet clear what could cause the elevated abundances of scandium, vanadium, and yttrium relative to other metals. Each of these elements is linked to a different source; scandium and vanadium are mainly produced in Type II and Type Ia supernovae, respectively, while yttrium is likely synthesized in asymptotic giant branch stars. Future observations of stars near the center of the Milky Way may help answer this question and further constrain the origin of our galaxys nuclear star cluster.CitationTuan Do et al 2018 ApJL 855 L5. doi:10.3847/2041-8213/aaaec3

  13. Advanced APS Impacts on Vehicle Payloads

    Science.gov (United States)

    Schneider, Steven J.; Reed, Brian D.

    1989-01-01

    Advanced auxiliary propulsion system (APS) technology has the potential to both, increase the payload capability of earth-to-orbit (ETO) vehicles by reducing APS propellant mass, and simplify ground operations and logistics by reducing the number of fluids on the vehicle and eliminating toxic, corrosive propellants. The impact of integrated cryogenic APS on vehicle payloads is addressed. In this system, launch propulsion system residuals are scavenged from integral launch propulsion tanks for use in the APS. Sufficient propellant is preloaded into the APS to return to earth with margin and noncomplete scavenging assumed. No propellant conditioning is required by the APS, but ambient heat soak is accommodated. High temperature rocket materials enable the use of the unconditioned hydrogen/oxygen in the APS and are estimated to give APS rockets specific impulse of up to about 444 sec. The payload benefits are quantified and compared with an uprated monomethyl hydrazine/nitrogen tetroxide system in a conservative fashion, by assuming a 25.5 percent weight growth for the hydrogen/oxygen system and a 0 percent weight growth for the uprated system. The combination and scavenging and high performance gives payload impacts which are highly mission specific. A payload benefit of 861 kg (1898 lbm) was estimated for a Space Station Freedom rendezvous mission and 2099 kg (4626 lbm) for a sortie mission, with payload impacts varying with the amount of launch propulsion residual propellants. Missions without liquid propellant scavenging were estimated to have payload penalties, however, operational benefits were still possible.

  14. 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

  15. Coaching Strategies for AP: Building a Successful AP European History Program

    Science.gov (United States)

    Fornaciari, Jim

    2014-01-01

    The October 2013 special issue of "Social Education" dealt with almost all AP social studies subjects, but omitted AP European History. This is one of the most fascinating AP subjects for students and teachers alike. In this article, the author shares his experiences since hewas given the responsibility of building his school's Advanced…

  16. ELECTROCHEMICAL CORROSION TESTING OF TANKS 241-AN-102 & 241-AP-107 & 241-AP-108 IN SUPPORT OF ULTRASONIC TESTING

    Energy Technology Data Exchange (ETDEWEB)

    WYRWAS RB; DUNCAN JB

    2008-11-20

    This report presents the results of the corrosion rates that were measured using electrochemical methods for tanks 241-AN-102 (AN-102), 241-AP-107 (AP 107), and 241-AP-108 (AP-108) performed under test plant RPP-PLAN-38215. The steel used as materials of construction for AN and AP tank farms was A537 Class 1. Test coupons of A537 Class 1 carbon steel were used for corrosion testing in the AN-107, AP-107, and AP-108 tank waste. Supernate will be tested from AN-102, AP-107, and Ap-108. Saltcake testing was performed on AP-108 only.

  17. Lightweight Double Neutron Star Found

    Science.gov (United States)

    Kohler, Susanna

    2018-02-01

    for such a system.Through meticulous observations over the span of 2.5 years, Martinez and collaborators were able to obtain a number of useful measurements for the system, including the pulsars period (62 ms), the period of the binary (2.62 days), and the systems eccentricity (e = 0.17).In addition, the team measured the rate of advance of periastron of the system, allowing them to estimate the total mass of the system: M = 2.54 solar masses. This mass, combined with the eccentricity of the orbit, demonstrate that the companion of the pulsar in PSR J1411+2551 is almost certainly a neutron star and the system is one of the lightest known to date, even including the double neutron-star merger that was observed by LIGO in August this past year.Constraining Stellar PhysicsBased on its measured properties, PSR J1411+2551 is most likely a recycled pulsar in a double neutron-star system. [Martinez et al. 2017]The intriguing orbital properties and low mass of PSR J1411+2551 have already allowed the authors to explore a number of constraints to stellar evolution models, including narrowing the possible equations of state for neutron stars that could produce such a system. These constraints will be interesting to compare to constraints from LIGO and Virgo in the future, as more merging neutron-star systems are observed.Meanwhile, our best bet for obtaining further constraints is to continue searching for more pre-merger double neutron-star systems like the Hulse-Taylor binary and PSR J1411+2551. Let the hunt continue!CitationJ. G. Martinez et al 2017 ApJL 851 L29. doi:10.3847/2041-8213/aa9d87

  18. Rapid variability of the EXor star NY Ori

    Science.gov (United States)

    Lorenzetti, D.; Arkharov, A. A.; Efimova, N.; Giannini, T.; Antoniucci, S.; Di Paola, A.; Larionov, V. M.

    2016-03-01

    We report on a rapid brightness variability of the classical EXor star NY Ori observed with the AZT24 1m IR telescope (Campo Imperatore, Italy), as a part of our program EXORCISM (EXOR OptiCal and Infrared Systematic Monitoring - Antoniucci et al. 2013 PPVI; Lorenzetti et al. 2009 ApJ 693, 1056).

  19. Antiphospholipid syndrome (APS) nephropathy in catastrophic, primary, and systemic lupus erythematosus-related APS.

    Science.gov (United States)

    Tektonidou, Maria G; Sotsiou, Flora; Moutsopoulos, Haralampos M

    2008-10-01

    Renal involvement in antiphospholipid syndrome (APS) has been poorly recognized. A renal small-vessel vasculopathy, defined as APS nephropathy, has recently been observed in small series of patients with primary APS (PAPS) and systemic lupus erythematosus (SLE)-APS. We examined the renal histologic, clinical, and laboratory characteristics of different groups of patients with APS including catastrophic APS (CAPS). Our study included all CAPS (n=6), PAPS (n=8), and SLE-APS (n=23) patients with biopsy-proven renal involvement who were referred to our departments. The kidney biopsy specimens were retrospectively examined by the same renal pathologist. APS nephropathy was diagnosed as previously described. Demographic, clinical, and laboratory data were recorded. All patients with CAPS had acute and chronic renal vascular lesions compatible with diagnosis of APS nephropathy. Thrombotic microangiopathy (TMA), the acute lesion, was observed in all CAPS patients. Fibrous intimal hyperplasia of interlobular arteries (FIH) and focal cortical atrophy (FCA) were the most common chronic vascular lesions, occurring in 4 of 6 (66.7%) and 3 of 6 (50%) patients with CAPS, respectively. TMA was detected in 3 of 8 (37.5%) patients with PAPS and in 8 of 23 (35%) patients with SLE-APS, while FIH and FCA were found with similar frequencies in all 3 groups. Hypertension, proteinuria, hematuria, and renal insufficiency were the most common renal manifestations of all APS groups. Acute and chronic APS nephropathy lesions were detected in all 3 APS groups. Acute lesions were more prominent in CAPS, while chronic lesions were found with similar frequencies in all groups. Hypertension, proteinuria, hematuria, and renal insufficiency were the most common renal manifestations of all APS groups.

  20. AP1000 Containment Design and Safety Assessment

    International Nuclear Information System (INIS)

    Wright, Richard F.; Ofstun, Richard P.; Bachere, Sebastien

    2002-01-01

    The AP1000 is an up-rated version of the AP600 passive plant design that recently received final design certification from the US NRC. Like AP600, the AP1000 is a two-loop, pressurized water reactor featuring passive core cooling and passive containment safety systems. One key safety feature of the AP1000 is the passive containment cooling system which maintains containment integrity in the event of a design basis accident. This system utilizes a high strength, steel containment vessel inside a concrete shield building. In the event of a pipe break inside containment, a high pressure signal actuates valves which allow water to drain from a storage tank atop the shield building. Water is applied to the top of the containment shell, and evaporates, thereby removing heat. An air flow path is formed between the shield building and the containment to aid in the evaporation and is exhausted through a chimney at the top of the shield building. Extensive testing and analysis of this system was performed as part of the AP600 design certification process. The AP1000 containment has been designed to provide increased safety margin despite the increased reactor power. The containment volume was increased to accommodate the larger steam generators, and to provide increased margin for containment pressure response to design basis events. The containment design pressure was increased from AP600 by increasing the shell thickness and by utilizing high strength steel. The passive containment cooling system water capacity has been increased and the water application rate has been scaled to the higher decay heat level. The net result is higher margins to the containment design pressure limit than were calculated for AP600 for all design basis events. (authors)

  1. 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

  2. Operation of the APS rf gun

    International Nuclear Information System (INIS)

    Lewellen, J. W.

    1998-01-01

    The Advanced Photon Source (APS) has a thermionic-cathode rf gun system capable of providing beam to the APS linac. The gun system consists of a 1.6-cell thermionic-cathode rf gun, a fast kicker for beam current control, and an alpha magnet for bunch compression and injection into the APS linac line. This system is intended for use both as an injector for positron creation, and as a first beam source for the Low-Energy Undulator Test Line (LEUTL) project [1]. The first measured performance characteristics of the gun are presented.

  3. Tank 241-AP-107, grab samples, 7AP-99-1, 7AP-99-3 and 7AP-99-4 analytical results for the final report

    Energy Technology Data Exchange (ETDEWEB)

    BELL, K.E.

    1999-08-12

    This document is the format IV, final report for the tank 241-AP-107 (AP-107) grab samples taken in May 1999 to address waste compatibility concerns. Chemical, radiochemical, and physical analyses on the tank AP-107 samples were performed as directed in Compatibility Grab Sampling and Analysis Plan for Fiscal year 1999. Any deviations from the instructions provided in the tank sampling and analysis plan (TSAP) were discussed in this narrative. Interim data were provided earlier to River Protection Project (RPP) personnel, however, the data presented here represent the official results. No notification limits were exceeded.

  4. Meet the APS Editors Coffee Break

    Science.gov (United States)

    2014-03-01

    The APS Journal Editors invite you to join them for conversation and light refreshments. The Editors will be available to answer questions, discuss your ideas, and listen to your comments about the journals. All are welcome to attend.

  5. Pentoxifylline Treatment in Acute Pancreatitis (AP)

    Science.gov (United States)

    2018-02-21

    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)

  6. AP1000 design and construction integration

    International Nuclear Information System (INIS)

    Winters, James W.; Clelland, Jill A.

    2004-01-01

    Construction costs of commercial nuclear generating plants must be reduced in order to expand the future use of nuclear energy. Two of the drivers of plant construction costs are the cost of financing during the construction duration and the substantial amount of skilled craft labor hours needed on site during construction. The application of information technology (IT) has been used to understand and reduce both of these drivers by establishing parallel construction paths using modules and integrating construction sequence review into the design process. In a program sponsored by EPRI, Westinghouse has modeled the construction of AP1000 in '4D' to show its viability, to improve its logic, to improve the plant design for constructibility and overall to reduce time and risk in the construction schedule. The design of most of AP1000 was constrained to be a duplicate of AP600 except where components required expansion for the higher power level. As a result, the construction schedule for AP1000 is as mature and as robust as that for AP600. Two areas important to the construction of AP1000 did require some design work because they could not remain the same as AP1000. First, the turbine building had to be redesigned to accommodate the larger turbine and its support systems. Again, as much of the AP600 design and philosophy as possible was retained. The building required enlargement and the basemat, foundations, steel structure and structural modules required modification. As concrete, steel, and equipment were defined by the designers, they were matched to the original AP600 turbine building schedule. This forced designers to assemble files to be consistent with building assembly activities and to think about constructibility as they defined the final design. Second, the reinforcement structure within the concrete under and supporting the containment vessel required detail design. Westinghouse was fortunate to have the constructor Obayashi of Japan recommend a detailed

  7. AP1000{sup TM} plant modularization

    Energy Technology Data Exchange (ETDEWEB)

    Cantarero L, C.; Demetri, K. J. [Westinghouse Electric Co., 1000 Westinghouse Drive, Cranberry Township, PA 16066 (United States); Quintero C, F. P., E-mail: cantarc@westinghouse.com [Westinghouse Electric Spain, Padilla 17, 28006 Madrid (Spain)

    2016-09-15

    The AP1000{sup TM} plant is an 1100 M We pressurized water reactor (PWR) with passive safety features and extensive plant simplifications that enhance construction, operation, maintenance and safety. Modules are used extensively in the design of the AP1000 plant nuclear island. The AP1000 plant uses modern, modular-construction techniques for plant construction. The design incorporates vendor-designed skids and equipment packages, as well as large, multi-ton structural modules and special equipment modules. Modularization allows traditionally sequential construction tasks to be completed simultaneously. Factory-built modules can be installed at the site in a planned construction schedule. The modularized AP1000 plant allows many more construction activities to proceed in parallel. This reduces plant construction calendar time, thus lowering the costs of plant financing. Furthermore, performing less work onsite significantly reduces the amount of skilled field-craft labor, which costs more than shop labor. In addition to labor cost savings, doing more welding and fabrication in a factory environment raises the quality of work, allowing more scheduling flexibility and reducing the amount of specialized tools required onsite. The site layout for the AP1000 plant has been established to support modular construction and efficient operations during construction. The plant layout is compact, using less space than previous conventional plant layouts. This paper provides and overview of the AP1000 plant modules with an emphasis on structural modules. Currently the Westinghouse AP1000 plant has four units under construction in China and four units under construction in the United States. All have shown successful fabrication and installation of various AP1000 plant modules. (Author)

  8. Accessing, Mining, and Archiving an On-line Database -- The APS Catalog of the POSS I

    Science.gov (United States)

    Humphreys, R. M.; Cabanela, J. E.; Kriessler, J.

    2000-12-01

    The APS Catalog of the POSS I is an on-line database of over 100 million stars and galaxies (http://aps.umn.edu). A unique subset of this database with over 218,000 galaxies within 30 degrees of the North Galactic Pole, the MAPS-NGP, is now available at our web site. This diameter--selected catalog (>= 10 arcsec) is the deepest galaxy catalog constructed over such a large area of the sky (3000 sq. degrees). The MAPS-NGP includes many additional parameters for the galaxy images not available in the APS Catalog. Working with members of our computer science department, we have developed a morphological classifier for galaxies that divides our galaxy type into three classes -- early, intermediate, and late. We have applied data mining techniques to identify the most useful image parameters for input into a neural network and decision--tree based classifier pipeline. We are also archiving the APS Catalog for distribution to astronomical data centers including NASA's ADC and SIMBAD at CDS. The extragalactic subset will be integrated into the NASA/IPAC extragalactic database(NED). The MAPS-NGP has already been provided to NED. The APS is supported by NASA's Applied Information Systems Research Program.

  9. Identification and treatment of APS renal involvement.

    Science.gov (United States)

    Tektonidou, M G

    2014-10-01

    Renal involvement in antiphospholipid syndrome (APS), either primary or systemic lupus erythematosus (SLE)-related APS, includes renal artery stenosis or thrombosis, renal infarction, renal vein thrombosis and a small-vessel vaso-occlusive nephropathy defined as "antiphospholipid antibody (aPL)-associated nephropathy." aPL-associated nephropathy is characterized by acute lesions, thrombotic microangiopathy, and chronic lesions such as fibrous intimal hyperplasia, organizing thrombi with or without recanalization, fibrous occlusions of arteries or arterioles and focal cortical atrophy. Systemic hypertension, hematuria, proteinuria (ranging from mild to nephrotic level) and renal insufficiency represent the major clinical manifestations associated with aPL-associated nephropathy. Similar renal histologic and clinical characteristics have been described among all different groups of patients with positive aPL (primary APS, SLE-related APS, catastrophic APS and SLE/non-APS with positive aPL). In patients with aPL-associated nephropathy lesions in the absence of other causes associated with similar histological characteristics, aPL testing needs to be considered. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  10. 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.

  11. Vascular Manifestations in Antiphospholipid Syndrome (APS): Is APS a Thrombophilia or a Vasculopathy?

    Science.gov (United States)

    Siddique, Salma; Risse, Jessie; Canaud, Guillaume; Zuily, Stéphane

    2017-09-04

    Antiphospholipid antibody syndrome (APS) is characterized primarily by thrombosis and pregnancy morbidity. Chronic vascular lesions can also occur. While the underlying mechanisms of these vascular lesions are not entirely known, there have been multiple theories describing the potential process of vasculopathy in APS and the various clinical manifestations associated with it. Recently, it has been demonstrated that endothelial proliferation in kidneys can be explained by the activation of the mammalian target of rapamycin complex (mTORC) pathway by antiphospholipid antibodies (aPL). These data support the existence of an APS-related vasculopathy in different locations which can explain-in part-the different manifestations of APS. This review focuses on the various manifestations of APS as a result of APS-related vasculopathy, as well as pathophysiology, current screening, and treatment options for clinicians to be aware of.

  12. A spectroscopic analysis of the chemically peculiar star HD 207561

    Science.gov (United States)

    Joshi, S.; Semenko, E.; Martinez, P.; Sachkov, M.; Joshi, Y. C.; Seetha, S.; Chakradhari, N. K.; Mary, D. L.; Girish, V.; Ashoka, B. N.

    2012-08-01

    In this paper we present a high-resolution spectroscopic analysis of the chemically peculiar star HD 207561. During a survey programme to search for new rapidly oscillating Ap (roAp) stars in the Northern hemisphere, Joshi et al. observed significant photometric variability on two consecutive nights in the year 2000. The amplitude spectra of the light curves obtained on these two nights showed oscillations with a frequency of 2.79 mHz (P ˜ 6 min). However, subsequent follow-up observations could not confirm any rapid variability. In order to determine the spectroscopic nature of HD 207561, high-resolution spectroscopic and spectropolarimetric observations were carried out. A reasonable fit of the calculated Hβ line profile to the observed one yields an effective temperature (Teff) and surface gravity (log g) of 7300 K and 3.7 dex, respectively. The derived projected rotational velocity (v sin i) for HD 207561 is 74 km s-1, indicative of a relatively fast rotator. The position of HD 207561 in the Hertzsprung-Russell diagram implies that this is slightly evolved from the main-sequence and located well within the δ-Scuti instability strip. The abundance analysis indicates the star has slight underabundances of Ca and Sc and mild overabundances of iron-peak elements. The spectropolarimetric study of HD 207561 shows that the effective magnetic field is within the observational error of 100 G. The spectroscopic analysis revealed that the star has most of the characteristics similar to an Am star, rather than an Ap star, and that it lies in the δ-Scuti instability strip; hence roAp pulsations are not expected in HD 207561, but low-overtone modes might be excited. The present work is based on the analysis of data collected with the Russian 6-m telescope BTA operated by the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS).

  13. Westinghouse AP600 advanced nuclear plant design

    International Nuclear Information System (INIS)

    Gangloff, W.

    1999-01-01

    As part of the cooperative US Department of Energy (DOE) Advanced Light Water Reactor (ALWR) Program and the Electric Power Research Institute (EPRI), the Westinghouse AP600 team has developed a simplified, safe, and economic 600-megawatt plant to enter into a new era of nuclear power generation. Designed to satisfy the standards set by DOE and defined in the ALWR Utility Requirements Document (URD), the Westinghouse AP600 is an elegant combination of innovative safety systems that rely on dependable natural forces and proven technologies. The Westinghouse AP600 design simplifies plant systems and significant operation, inspections, maintenance, and quality assurance requirements by greatly reducing the amount of valves, pumps, piping, HVAC ducting, and other complex components. The AP600 safety systems are predominantly passive, depending on the reliable natural forces of gravity, circulation, convection, evaporation, and condensation, instead of AC power supplies and motor-driven components. The AP600 provides a high degree of public safety and licensing certainty. It draws upon 40 years of experience in light water reactor components and technology, so no demonstration plant is required. During the AP600 design program, a comprehensive test program was carried out to verify plant components, passive safety systems components, and containment behavior. When the test program was completed at the end of 1994, the AP600 became the most thoroughly tested advanced reactor design ever reviewed by the US Nuclear Regulatory Commission (NRC). The test results confirmed the exceptional behavior of the passive systems and have been instrumental in facilitating code validations. Westinghouse received Final Design Approval from the NRC in September 1998. (author)

  14. Giant CP stars

    International Nuclear Information System (INIS)

    Loden, L.O.; Sundman, A.

    1989-01-01

    This study is part of an investigation of the possibility of using chemically peculiar (CP) stars to map local galactic structure. Correct luminosities of these stars are therefore crucial. CP stars are generally regarded as main-sequence or near-main-sequence objects. However, some CP stars have been classified as giants. A selection of stars, classified in literature as CP giants, are compared to normal stars in the same effective temperature interval and to ordinary 'non giant' CP stars. There is no clear confirmation of a higher luminosity for 'CP giants', than for CP stars in general. In addition, CP characteristics seem to be individual properties not repeated in a component star or other cluster members. (author). 50 refs., 5 tabs., 3 figs

  15. Tank 241-AP-107, grab samples 7AP-97-1, 7AP-97-2 and 7AP-97-3 analytical results for the final report

    Energy Technology Data Exchange (ETDEWEB)

    Steen, F.H.

    1997-12-22

    This document is the final report for tank 241-AP-107 grab samples. Three grab samples were collected from riser 1 on September 11, 1997. Analyses were performed on samples 7AP-97-1, 7AP-97-2 and 7AP-97-3 in accordance with the Compatibility Grab Sampling and Analysis Plan (TSAP) (Sasaki, 1997) and the Data Quality Objectives for Tank Farms Waste Compatibility Program (DQO) (Rev. 1: Fowler, 1995; Rev. 2: Mulkey and Nuier, 1997). The analytical results are presented in the data summary report (Table 1). A notification was made to East Tank Farms Operations concerning low hydroxide in the tank and a hydroxide (caustic) demand analysis was requested. The request for sample analysis (RSA) (Attachment 2) received for AP-107 indicated that the samples were polychlorinated biphenyl (PCB) suspects. Therefore, prior to performing the requested analyses, aliquots were made to perform PCB analysis in accordance with the 222-S Laboratory administrative procedure, LAP-101-100. The results of this analysis indicated that no PCBs were present at 50 ppm and analysis proceeded as non-PCB samples. The results and raw data for the PCB analysis will be included in a revision to this document. The sample breakdown diagrams (Attachment 1) are provided as a cross-reference for relating the tank farm customer identification numbers with the 222-S Laboratory sample numbers and the portion of sample analyzed.

  16. NICER Eyes on Bursting Stars

    Science.gov (United States)

    Kohler, Susanna

    2018-03-01

    , we dont yet understand the impact that these X-ray flashes have on the accretion disk and the environment surrounding the neutron star. In a new study led by Laurens Keek (University of Maryland), a team of scientists now details what NICER has learned on this subject.Extra X-RaysLight curve (top) and hardness ratio (bottom) for the X-ray burst from Aql X-1 captured by NICER on 3 July 2017. [Keek et al. 2018]In addition to thermal emission from the neutron star, NICER revealed an excess of soft X-ray photons below 1 keV during Aql X-1s burst. The authors propose two possible models for this emission:The burst radiation from the neutron stars surface was reprocessed i.e., either scattered or absorbed and re-emitted by the accretion disk.The persistent, usual accretion flow was enhanced as a result of the bursts radiation drag on the disk, briefly bumping up the disks X-ray flux.While we cant yet conclusively statewhich mechanismdominates, NICERs observations do show that bursts have a substantial impact on their accretion environment. And, as there are over 100 such X-ray burster systems in our galaxy, we can expect that NICER will allow us to better explore the effect of X-ray bursts on neutron-star disks and their surroundings inmany different systems in the future.BonusCheck out the awesome gif below, provided by NASA, which shows NICER being extracted fromthe Dragon capsules trunk by a robotic arm.CitationL. Keek et al 2018 ApJL 855 L4. doi:10.3847/2041-8213/aab104

  17. Energy production in stars

    International Nuclear Information System (INIS)

    Bethe, Hans.

    1977-01-01

    Energy in stars is released partly by gravitation, partly by nuclear reactions. For ordinary stars like our sun, nuclear reactions predominate. However, at the end of the life of a star very large amounts of energy are released by gravitational collapse; this can amount to as much as 10 times the total energy released nuclear reactions. The rotational energy of pulsars is a small remnant of the energy of gravitation. The end stage of small stars is generally a white dwarf, of heavy stars a neutron star of possibly a black hole

  18. Rates of star formation

    International Nuclear Information System (INIS)

    Larson, R.B.

    1977-01-01

    It is illustrated that a theoretical understanding of the formation and evolution of galaxies depends on an understanding of star formation, and especially of the factors influencing the rate of star formation. Some of the theoretical problems of star formation in galaxies, some approaches that have been considered in models of galaxy evolution, and some possible observational tests that may help to clarify which processes or models are most relevant are reviewed. The material is presented under the following headings: power-law models for star formation, star formation processes (conditions required, ways of achieving these conditions), observational indications and tests, and measures of star formation rates in galaxies. 49 references

  19. Building an AP Social Studies Program with Non-Traditional AP Students

    Science.gov (United States)

    Ashmead, Amanda; Blanchette, Sue

    2013-01-01

    Equal access to education, that is to a high quality education, has increasingly come to mean access to an Advanced Placement program. In recent years, there has been steady attention paid to opening access to AP programs. The 9th annual College Board report (2013) stated "students who succeed on an AP Exam during high school typically…

  20. 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...

  1. Regular Generalized Star Star closed sets in Bitopological Spaces

    OpenAIRE

    K. Kannan; D. Narasimhan; K. Chandrasekhara Rao; R. Ravikumar

    2011-01-01

    The aim of this paper is to introduce the concepts of τ1τ2-regular generalized star star closed sets , τ1τ2-regular generalized star star open sets and study their basic properties in bitopological spaces.

  2. 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)

  3. Quark core stars, quark stars and strange stars

    International Nuclear Information System (INIS)

    Grassi, F.

    1988-01-01

    A recent one flavor quark matter equation of state is generalized to several flavors. It is shown that quarks undergo a first order phase transition. In addition, this equation of state depends on just one parameter in the two flavor case, two parameters in the three flavor case, and these parameters are constrained by phenomenology. This equation of state is then applied to the hadron-quark transition in neutron stars and the determination of quark star stability, the investigation of strange matter stability and possible strange star existence. 43 refs., 6 figs

  4. Shuttle APS propellant thermal conditioner study

    Science.gov (United States)

    Pearson, W. E.

    1971-01-01

    A study program was performed to allow selection of thermal conditioner assemblies for superheating O2 and H2 at supercritical pressures. The application was the auxiliary propulsion system (APS) for the space shuttle vehicle. The O2/H2 APS propellant feed system included propellant conditioners, of which the thermal conditioner assemblies were a part. Cryogens, pumped to pressures above critical, were directed to the thermal conditioner assembly included: (1) a gas generator assembly with ignition system and bipropellant valves, which burned superheated O2 and H2 at rich conditions; (2) a heat exchanger assembly for thermal conditioning of the cryogenic propellant; and (3) a dump nozzle for heat exchanger exhaust.

  5. An analysis of AP600 design features

    International Nuclear Information System (INIS)

    Park, Jong Kyoon; Jang, Moon Heui; Hwang, Yung Dong

    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)

  6. Magnetic fields in non-convective regions of stars.

    Science.gov (United States)

    Braithwaite, Jonathan; Spruit, Henk C

    2017-02-01

    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.

  7. ENERGY STAR Certified Televisions

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 7.0 ENERGY STAR Program Requirements for Televisions that are effective as of October 30,...

  8. mSTAR

    Data.gov (United States)

    National Aeronautics and Space Administration — Mini-STAR (mSTAR) is a small satellite mission concept to test the hypothesis that the velocity of light is independent of the velocity and orientation of the...

  9. 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,...

  10. Observations of central stars

    International Nuclear Information System (INIS)

    Lutz, J.H.

    1978-01-01

    Difficulties occurring in the observation of central stars of planetary nebulae are reviewed with emphasis on spectral classifications and population types, and temperature determination. Binary and peculiar central stars are discussed. (U.M.G.)

  11. 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....

  12. 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 4.1 ENERGY STAR Program Requirements for Furnaces that are effective as of February 1,...

  13. ENERGY STAR Certified Telephones

    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 Telephony (cordless telephones and VoIP...

  14. ENERGY STAR Certified Dehumidifiers

    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 Dehumidifiers that are effective as of October...

  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. Observations of a Windy Star

    Science.gov (United States)

    Kohler, Susanna

    2017-06-01

    -alpha emission from this star. Now, however, a team of scientists from Steward Observatory, University of Arizona have changed this.Confirming the ModelLed by Ya-Lin Wu, the team obtained diffraction-limited images of Eta Carinae using the Magellan adaptive optics system. The observations, made in both H-alpha and continuum, show that the H-alpha emitting region is significantly wider than the continuum emitting region, as predicted by the model. In fact, the measured emission implies that the H-alpha line-forming region may have a characteristic emitting radius of 2530 AU in very good agreement with the Hillier et al. stellar-wind model.This confirmation is strong support of the physical wind parameters estimated for Eta Carinae in the model, like the mass-loss rate of 10^-3 solar masses per year. These parameters are enormously helpful as we attempt to understand the physics of strong stellar-wind mass loss and the late evolutionary phases of very massive stars.CitationYa-Lin Wu et al 2017 ApJL 841 L7. doi:10.3847/2041-8213/aa70ed

  17. 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…

  18. 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).

  19. VizieR Online Data Catalog: UV spectra of classical T Tauri stars (France+, 2014)

    Science.gov (United States)

    France, K.; Schindhelm, E.; Bergin, E. A.; Roueff, E.; Abgrall, H.

    2017-06-01

    We present 16 objects from the larger GTO + DAO T Tauri star samples described by Ardila et al. (2013ApJS..207....1A; focusing on the hot gas emission lines) and France et al. (2012, J/ApJ/756/171; focusing on the molecular circumstellar environment). Eleven of the 16 sources were observed as part of the DAO of Tau guest observing program (PID 11616; PI: G. Herczeg), four were part of the COS Guaranteed Time Observing program on protoplanetary disks (PIDs 11533 and 12036; PI: J. Green), and we have included archival STIS observations of the well-studied CTTS TW Hya (Herczeg et al. 2002ApJ...572..310H, 2004ApJ...607..369H), obtained through StarCAT (Ayres 2010, J/ApJS/187/149). The targets were selected by the availability of reconstructed Lyα spectra, as this emission line is a critical component to the intrinsic CTTS UV radiation field (Schindhelm et al. 2012ApJ...756L..23S) and has not been uniformly included in recent studies of the CTTS radiation field (e.g., Ingleby et al. 2011AJ....141..127I; Yang et al. 2012, J/ApJ/744/121). Most of the targets were observed with the medium-resolution FUV modes of COS (G130M and G160M; Green et al. 2012ApJ...744...60G). (2 data files).

  20. Tank 241-AP-107 tank characterization plan

    International Nuclear Information System (INIS)

    Schreiber, R.D.

    1994-01-01

    This document is a plan which serves as the contractual agreement between the Characterization Program, Sampling Operations, WHC 222-S Laboratory, and PNL 325 Analytical Chemistry Laboratory. The scope of this plan is to provide guidance for the sampling and analysis of samples from tank 241-AP-107

  1. 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.

  2. The Promise of AP World History

    Science.gov (United States)

    Saldaña, Cristóbal T.

    2013-01-01

    AP World History is the ideal history course. It introduces students to 10,000 years of world history, and demands critical reading, critical writing, and critical thinking skills on the part of both the teacher and the students. It requires students to build their expertise in reading their textbook, and places demands on the teacher to assign…

  3. Meet the Editors of APS Reception

    Science.gov (United States)

    The Editors of the APS journals invite you to join them for conversation on Tuesday, March 15, 4:30-6:00 pm. The Editors will be available to answer questions, hear your ideas, and discuss any comments about the journals. All are welcome. Light refreshments will be served.

  4. The Demographic Wave: Rethinking Hispanic AP Trends

    Science.gov (United States)

    Edwards, Kelcey; Sawtell, Ellen

    2013-01-01

    Presented at the Advanced Placement Annual Conference (APAC) in Las Vegas, NV in July 2013. This presentation reviews new research examining the AP® experience of Hispanic graduates over the past decade. Topics include an in-depth look at the AP Spanish Language and Culture gateway hypothesis and trends in family characteristics such as parent…

  5. 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,…

  6. Rotating Stars in Relativity

    Directory of Open Access Journals (Sweden)

    Stergioulas Nikolaos

    2003-01-01

    Full Text Available Rotating relativistic stars have been studied extensively in recent years, both theoretically and observationally, because of the information they might yield about the equation of state of matter at extremely high densities and because they are considered to be promising sources of gravitational waves. The latest theoretical understanding of rotating stars in relativity is reviewed in this updated article. The sections on the equilibrium properties and on the nonaxisymmetric instabilities in f-modes and r-modes have been updated and several new sections have been added on analytic solutions for the exterior spacetime, rotating stars in LMXBs, rotating strange stars, and on rotating stars in numerical relativity.

  7. Magnetism of hot stars

    Science.gov (United States)

    Wade, G. A.; Neiner, C.

    2018-01-01

    Strong, stable, and organised magnetic fields are present at the surfaces of a small fraction of OBA stars. These "fossil fields" exhibit uniform characteristics in stars over a tremendous range of stellar mass, age, temperature, and rotation rate. In hot O- and B-type stars, these magnetic fields couple efficiently to the stellar radiatively driven winds, strongly influencing stellar mass loss and rotation. In this article we review the characteristics of the known magnetic hot stars, discuss recent discoveries and insights, and describe recent theoretical progress toward understanding basic field properties and the influence of magnetic fields on hot star evolution.

  8. 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

  9. 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.

  10. Ponderable soliton stars

    Science.gov (United States)

    Chiu, Hong-Yee

    1990-01-01

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

  11. 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.

  12. 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.

  13. CLEARING MAGNET DESIGN FOR APS-U

    Energy Technology Data Exchange (ETDEWEB)

    Abliz, M.; Grimmer, J.; Jaski, Y.; Westferro, F.; Ramanathan, M.

    2017-06-25

    The Advanced Photon Source is in the process of developing an upgrade (APS-U) of the storage ring. The upgrade will be converting the current double bend achromat (DBA) lattice to a multi-bend achromat (MBA) lattice. In addition, the storage ring will be operated at 6 GeV and 200 mA with regular swap-out injection to keep the stored beam current constant [1]. The swap-out injection will take place with beamline shutters open. For radiation safety to ensure that no electrons can exit the storage ring, a passive method of protecting the beamline and containing the electrons inside the storage ring is proposed. A clearing magnet will be located in all beamline front ends inside the storage ring tunnel. This article will discuss the features and design of the clearing magnet scheme for APS-U.

  14. 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.

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

    International Nuclear Information System (INIS)

    Esch, R.A.

    1996-01-01

    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

  16. 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…

  17. Beryllium window for an APS diagnostics beamline

    International Nuclear Information System (INIS)

    Sheng, I.C.; Yang, B.X.; Sharma, Y.S.

    1997-01-01

    A beryllium (Be) window for an Advanced Photon Source (APS) diagnostics beamline has been designed and built. The window, which has a double concave axisymmetrical profile with a thickness of 0.5 mm at the center, receives 160 W/mm 2 (7 GeV/100 mA stored beam) from an undulator beam. The window design as well as thermal and thermomechanical analyses, including thermal buckling of the Be window, are presented

  18. Children born to SLE and APS mothers.

    Science.gov (United States)

    Nalli, C; Iodice, A; Andreoli, L; Lojacono, A; Motta, M; Fazzi, E; Tincani, A

    2014-10-01

    Systemic lupus erythematosus (SLE) and antiphospholipid antibody syndrome (APS) are autoimmune diseases that affect women of childbearing age. Pregnancies in these patients carry several complications such as prematurity. Maternal IgG antiphospholipid antibodies (aPL) can cross the placenta but they don't generally cause any neonatal thrombotic event. Because of the incompleteness of the fetal blood-brain barrier, aPL could theoretically reach the fetal brain. Whether this can have an effect on brain development is still under investigation. Some studies performed in children of patients with SLE and/or APS showed an increased number of learning disabilities without impairment in intelligence level. The objectives of this article are to evaluate the neurodevelopment outcome in 30 children (median age 9 years) born to mothers with SLE and/or APS with IgG anti-beta2-glycoprotein I during the third trimester of pregnancy and found positive for the same antibodies at birth. A neurological physical exam was performed in all children. We submitted some questionnaires to the mothers: the Child Behavior CheckList (CBCL) and a homemade set of questions obtained by a team composed of rheumatologists and pediatric neurologists. Intellectual functioning was determined by the Wechsler scale for corrected age. In all children neurological physical exam and intelligence levels were found to be normal but mild behavior disorders and history of neurological manifestations were shown in three children. Offspring of patients with SLE and/or APS are generally healthy. We and others observed the occurrence of minor neurological disorders that might be related to maternal disease or to prematurity. The limited number of the available data on this sensitive issue supports the need for further studies. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  19. Overview of the advanced photon source (APS)

    International Nuclear Information System (INIS)

    White, M.M.

    1994-01-01

    The Advanced Photon Source (APS) is a state-of-the-art synchrotron light source facility dedicated to the production of extremely brilliant x-ray beams for research. Its super-intense x-ray beams will be used in many areas of research including industrial research, biological and medical research, defense-related research, and basic research. The APS x-ray beams will allow scientists to study smaller samples, more complex systems, faster reactions and processes, and gather data at a greater level of detail than has been possible to date. Creation of these beams begins with electron production by an electron gun with a thermionic cathode. The electrons are accelerated to 200 MeV by a linear accelerator (linac) and then impinge on a tungsten target, resulting in electron-positron pair production. The positrons are accelerated to 450 MeV in the remainder of the linac, then accumulated, damped, and transferred to a synchrotron that increases their energy to 7 GeV. The 7-GeV positrons are injected into a storage ring, where they pass through special magnets that cause them to emit x-rays of the desired quality. Construction at ANL is nearly complete at this time, and the APS will begin operating for users in 1996. The accelerator and experimental facilities are described in this paper, and a brief overview of some of the experimental programs is given

  20. APS - Diagnostics and challenges for the future.

    Science.gov (United States)

    Pengo, V; Bison, E; Zoppellaro, G; Padayattil Jose, S; Denas, G; Hoxha, A; Ruffatti, A; Banzato, A

    2016-11-01

    Diagnosis of antiphospholipid syndrome (APS) is essentially based on the detection of circulating antiphospholipid (aPL) antibodies. Progress have been made on the standardization of tests exploring the presence of aPL as guidelines on coagulation and immunological tests were recently published in the literature. Clinical relevance of aPL profile has come from prospective cohort studies in populations with a homogeneous antibody profile supporting the view that triple positivity is a high risk pattern in patients and carriers. In addition to the classic ones, several other tests have been proposed for the diagnosis of APS. The detection of antibodies directed to domain 1 and 4/5 of β2-Glycoprotein I (β2GP1) were found to be particularly sound. Several issues remain to be addressed. We do not yet know what is the physiological function of β2GP1 and the pathophysiology of thrombosis and pregnancy loss in these patients. Moreover, treatment is poorly defined especially in the case of feared catastrophic APS. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. On the periodic variations of geomagnetic activity indices Ap and ap

    Directory of Open Access Journals (Sweden)

    H. Schreiber

    1998-05-01

    Full Text Available Yearly averages of geomagnetic activity indices Ap for the years 1967–1984 are compared to the respective averages of ν2·Bs, where v is the solar wind velocity and Bs is the southward interplanetary magnetic field (IMF component. The correlation of both quantities is known to be rather good. Comparing the averages of Ap with ν2 and Bs separately we find that, during the declining phase of the solar cycle, ν2 and during the ascending phase Bs have more influence on Ap. According to this observation (using Fourier spectral analysis the semiannual and 27 days, Ap variations for the years 1932–1993 were analysed separately for years before and after sunspot minima. Only those time-intervals before sunspot minima with a significant 27-day recurrent period of the IMF sector structure and those intervals after sunspot minima with a significant 28-28.5-day recurrent period of the sector structure were used. The averaged spectra of the two Ap data sets clearly show a period of 27 days before and a period of 28–29 days after sunspot minimum. Moreover, the phase of the average semiannual wave of Ap is significantly different for the two groups of data: the Ap variation maximizes near the equinoxes during the declining phase of the sunspot cycle and near the beginning of April and October during the ascending phase of the sunspot cycle, as predicted by the Russell-McPherron (R-M mechanism. Analysing the daily variation of ap in an analogue manner, the same equinoctial and R-M mechanisms are seen, suggesting that during phases of the solar cycle, when ap depends more on the IMF-Bs component, the R-M mechanism is predominant, whereas during phases when ap increases as v increases the equinoctial mechanism is more likely to be effective.Key words. Interplanetary physics · Magnetic fields · Solar wind plasma · Solar wind · magnetosphere interaction

  2. 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.

  3. Seeing Stars in Serpens

    Science.gov (United States)

    2006-01-01

    Infant stars are glowing gloriously in this infrared image of the Serpens star-forming region, captured by NASA's Spitzer Space Telescope. The reddish-pink dots are baby stars deeply embedded in the cosmic cloud of gas and dust that collapsed to create it. A dusty disk of cosmic debris, or 'protoplanetary disk,' that may eventually form planets, surrounds the infant stars. Wisps of green throughout the image indicate the presence of carbon rich molecules called polycyclic aromatic hydrocarbons. On Earth, these molecules can be found on charred barbecue grills and in automobile exhaust. Blue specks sprinkled throughout the image are background stars in our Milky Way galaxy. The Serpens star-forming region is located approximately 848 light-years away in the Serpens constellation. The image is a three-channel, false-color composite, where emission at 4.5 microns is blue, emission at 8.0 microns is green, and 24 micron emission is red.

  4. Slowly pulsating B stars

    Science.gov (United States)

    Waelkens, C.

    1991-06-01

    Photometric data obtained during several years of observations of seven B-type stars are analyzed, including HD 74195 (Omicron Velorum), HD 74560 (HD 3467), HD 123515 (HR 5296), HD 143309, HD 160124, HD 177863 (HR 7241), and HD 181558 (HR 7339). Results indicate that all seven stars are multiperiodic variables with periods of the order of days. Two periods were identified for HD 177863, three periods for HD 74560 and HD 181558, four periods for HD 123515, five periods for HD 74195, six periods for HD 143309, and eight periods for HD 160124. The multiperiodicity and the amplitude behavior of these stars point toward pulsation in high-radial-order g-modes in the stars. It is suggested that these stars form a distinct group of early-type variables, which are named here 'slowly pulsating B stars'.

  5. Small Molecule Inhibitors Targeting Activator Protein 1 (AP-1)

    Science.gov (United States)

    2015-01-01

    Activator protein 1 (AP-1) is a pivotal transcription factor that regulates a wide range of cellular processes including proliferation, apoptosis, differentiation, survival, cell migration, and transformation. Accumulating evidence supports that AP-1 plays an important role in several severe disorders including cancer, fibrosis, and organ injury, as well as inflammatory disorders such as asthma, psoriasis, and rheumatoid arthritis. AP-1 has emerged as an actively pursued drug discovery target over the past decade. Excitingly, a selective AP-1 inhibitor T-5224 (51) has been investigated in phase II human clinical trials. Nevertheless, no effective AP-1 inhibitors have yet been approved for clinical use. Despite significant advances achieved in understanding AP-1 biology and function, as well as the identification of small molecules modulating AP-1 associated signaling pathways, medicinal chemistry efforts remain an urgent need to yield selective and efficacious AP-1 inhibitors as a viable therapeutic strategy for human diseases. PMID:24831826

  6. Nagyszombat and the stars

    Science.gov (United States)

    Zsoldos, E.

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

  7. Evolution of massive stars

    International Nuclear Information System (INIS)

    Loore, C. de

    1984-01-01

    The evolution of stars with masses larger than 15 sun masses is reviewed. These stars have large convective cores and lose a substantial fraction of their matter by stellar wind. The treatment of convection and the parameterisation of the stellar wind mass loss are analysed within the context of existing disagreements between theory and observation. The evolution of massive close binaries and the origin of Wolf-Rayet Stars and X-ray binaries is also sketched. (author)

  8. A novel homozygous AP4B1 mutation in two brothers with AP-4 deficiency syndrome and ocular anomalies.

    Science.gov (United States)

    Accogli, Andrea; Hamdan, Fadi F; Poulin, Chantal; Nassif, Christina; Rouleau, Guy A; Michaud, Jacques L; Srour, Myriam

    2018-04-01

    Adaptor protein complex-4 (AP-4) is a heterotetrameric protein complex which plays a key role in vesicle trafficking in neurons. Mutations in genes affecting different subunits of AP-4, including AP4B1, AP4E1, AP4S1, and AP4M1, have been recently associated with an autosomal recessive phenotype, consisting of spastic tetraplegia, and intellectual disability (ID). The overlapping clinical picture among individuals carrying mutations in any of these genes has prompted the terms "AP-4 deficiency syndrome" for this clinically recognizable phenotype. Using whole-exome sequencing, we identified a novel homozygous mutation (c.991C>T, p.Q331*, NM_006594.4) in AP4B1 in two siblings from a consanguineous Pakistani couple, who presented with severe ID, progressive spastic tetraplegia, epilepsy, and microcephaly. Sanger sequencing confirmed the mutation was homozygous in the siblings and heterozygous in the parents. Similar to previously reported individuals with AP4B1 mutations, brain MRI revealed ventriculomegaly and white matter loss. Interestingly, in addition to the typical facial gestalt reported in other AP-4 deficiency cases, the older brother presented with congenital left Horner syndrome, bilateral optic nerve atrophy and cataract, which have not been previously reported in this condition. In summary, we report a novel AP4B1 homozygous mutation in two siblings and review the phenotype of AP-4 deficiency, speculating on a possible role of AP-4 complex in eye development. © 2018 Wiley Periodicals, Inc.

  9. 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...... tree is isomorphic to T? We prove that in the general setting, CST is NP-complete, which implies that the tree edit distance considered here is also NP-hard, even when both input trees having diameters bounded by 10. We also show that, when the number of distinct stars is bounded by a constant k, CTS...

  10. 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...... tree is isomorphic to T? We prove that in the general setting, CST is NP-complete, which implies that the tree edit distance considered here is also NP-hard, even when both input trees having diameters bounded by 10. We also show that, when the number of distinct stars is bounded by a constant k, CTS...

  11. Massive soliton stars

    Science.gov (United States)

    Chiu, Hong-Yee

    1990-01-01

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

  12. 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

  13. 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...

  14. Horizontal Branch stars as AmFm/HgMn stars

    OpenAIRE

    Michaud, G.; Richer, J.

    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.

  15. 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...

  16. Teaching Materials and Strategies for the AP Music Theory Exam

    Science.gov (United States)

    Lively, Michael T.

    2017-01-01

    Each year, many students take the Advanced Placement (AP) Music Theory Exam, and the majority of these students enroll in specialized AP music theory classes as part of the preparation process. For the teachers of these AP music theory classes, a number of challenges are presented by the difficulty and complexity of the exam subject material as…

  17. A Heavy Flavor Tracker for STAR

    International Nuclear Information System (INIS)

    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.

    2008-01-01

    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 APS sensors 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

  18. Dicty_cDB: FC-AP07 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available FC (Link to library) FC-AP07 (Link to dictyBase) - - - Contig-U15932-1 FC-AP07P (Li...nk to Original site) FC-AP07F 546 FC-AP07Z 446 FC-AP07P 992 - - Show FC-AP07 Library FC (Link to library) Clone ID FC-AP...al site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/FC/FC-AP/FC-AP07Q.Seq.d/ Representative seq. ID FC-AP...07P (Link to Original site) Representative DNA sequence >FC-AP07 (FC-AP07Q) /CSM/FC/FC-AP/FC-AP...ificant alignments: (bits) Value FC-AP07 (FC-AP07Q) /CSM/FC/FC-AP/FC-AP07Q.Seq.d/ 1148 0.0 SSM404 (SSM404Q)

  19. Dicty_cDB: FC-AP08 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available FC (Link to library) FC-AP08 (Link to dictyBase) - - - Contig-U16116-1 FC-AP08P (Li...nk to Original site) FC-AP08F 125 FC-AP08Z 352 FC-AP08P 477 - - Show FC-AP08 Library FC (Link to library) Clone ID FC-AP...al site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/FC/FC-AP/FC-AP08Q.Seq.d/ Representative seq. ID FC-AP...08P (Link to Original site) Representative DNA sequence >FC-AP08 (FC-AP08Q) /CSM/FC/FC-AP/FC-AP... (VSA612Q) /CSM/VS/VSA6-A/VSA612Q.Seq.d/ 624 e-178 FC-AP08 (FC-AP08Q) /CSM/FC/FC-AP/FC-AP

  20. Merging strangeon stars

    Science.gov (United States)

    Lai, Xiao-Yu; Yu, Yun-Wei; Zhou, En-Ping; Li, Yun-Yang; Xu, Ren-Xin

    2018-02-01

    The state of supranuclear matter in compact stars remains puzzling, and it is argued that pulsars could be strangeon stars. What would happen if binary strangeon stars merge? This kind of merger could result in the formation of a hyper-massive strangeon star, accompanied by bursts of gravitational waves and electromagnetic radiation (and even a strangeon kilonova explained in the paper). The tidal polarizability of binary strangeon stars is different from that of binary neutron stars, because a strangeon star is self-bound on the surface by the fundamental strong force while a neutron star by the gravity, and their equations of state are different. Our calculation shows that the tidal polarizability of merging binary strangeon stars is favored by GW170817. Three kinds of kilonovae (i.e., of neutron, quark and strangeon) are discussed, and the light curve of the kilonova AT 2017 gfo following GW170817 could be explained by considering the decaying strangeon nuggets and remnant star spin-down. Additionally, the energy ejected to the fireball around the nascent remnant strangeon star, being manifested as a gamma-ray burst, is calculated. It is found that, after a prompt burst, an X-ray plateau could follow in a timescale of 102 ‑ 103 s. Certainly, the results could be tested also by further observational synergies between gravitational wave detectors (e.g., Advanced LIGO) and X-ray telescopes (e.g., the Chinese HXMT satellite and eXTP mission), and especially if the detected gravitational wave form is checked by peculiar equations of state provided by the numerical relativistical simulation.

  1. 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.

  2. Comparing traditional AP classes to portfolio AP classes in effectiveness of measuring knowledge.

    Directory of Open Access Journals (Sweden)

    Olona, L.

    2017-07-01

    Full Text Available High school students across the United States and internationally take Advanced Placement exams in May each year. These students also spend their school year enrolled in an Advanced Placement (AP class in preparation for the exam. There is a lack of research on any correlation between a student’s performance in class and performance on the exam. This study aims to compare the difference in correlation between traditional AP classes and portfolio AP classes. Second-semester grades and exam scores were collected from 2015 and 2016 from Norman High School students. Traditional classes had weak, if any, correlation, and portfolio classes presented no correlation. This lack of a relationship between class grade and exam score implies that students are unable to gauge their future exam performance based on class performance. Future researchers should compare data for a greater sample of students as well as regional samples.

  3. 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.

  4. The APS thin pulsed septum magnets

    International Nuclear Information System (INIS)

    Lopez, F.; Mills, F.; Milton, S.; Reeves, S.; Sheynin, S.; Thompson, K.; Turner, L.

    1994-01-01

    A thin (2-mm) eddy-current pulsed septum magnet was developed for use in the Advanced Photon Source (APS) machines. A number of different configurations of the magnet were assembled and tested in an effort to minimize the undesired leakage field in the stored-beam region. However, because of measured excessive leakage fields, an alternative direct-drive septum magnet was also constructed and tested. We present here the design specifications and acceptable performance criteria along with results of magnetic field measurements

  5. Tumores de apéndice cecal

    Directory of Open Access Journals (Sweden)

    Rubén Bembilbre Taboada

    1998-08-01

    Full Text Available Se realizó un estudio descriptivo-retrospectivo de 8 pacientes con tumores de apéndice cecal, en el período comprendido entre el 1 de enero de 1990 y el 1 de enero de 1997, los cuales fueron intervenidos quirúrgicamente en el Hospital Provincial Clinicoquirúrgico Docente "Dr. Gustavo Aldereguía". Se revisaron todos los libros de biopsias del Departamento de Anatomía Patológica correspondientes al período analizado, para obtener aquellos casos con diagnóstico de afección tumoral de apéndice. Se estudiaron las historias clínicas y se recogieron datos de interés como sexo, manifestaciones clínicas, diagnóstico presuntivo, diagnóstico anatomopatológico y tipo de intervención. La afección tumoral de apéndice cecal es infrecuente y constituyó el 0,38% del total de 20057 apéndices examinadas. No se hallaron diferencias respecto al sexo. Hubo un ligero predominio en pacientes con edades de más de 60 años. Los hallazgos clínicos más frecuentes fueron dolor agudo en fosa inguinal derecha y fiebre, con predominio del adenocarcinoma. Los principales resultados se exponen en tablasA retrospective-descriptive study of 8 patients with appendix ceci tumors attending the hospital from January 1st, 1990 to January 1st 1997 was made. These patients were operated at "Dr. Gustavo Aldereguía" clinical surgical teaching hospital in Cienfuegos. All the biopsy records of the analyzed period were checked in the Pathological Anatomy Department so as to collect those cases diagnosed with appendix ceci tumors. Medical records were examined and interesting data were collected as follows: sex, clinical symptoms, presumptive diagnosis, anatomopathological diagnosis and type of surgery. Tumors in appendix ceci are unusual and represented 0.38 % of 20 057 analyzed appendixes. Sex was not a determining factor. The disease was slightly predominant in patients over 60. The most frequent clinical findings were: nagging pain in the right inguinal fosa and

  6. Studies of microparticles in patients with the antiphospholipid syndrome (APS).

    Science.gov (United States)

    Vikerfors, A; Mobarrez, F; Bremme, K; Holmström, M; Ågren, A; Eelde, A; Bruzelius, M; Antovic, A; Wallén, H; Svenungsson, E

    2012-06-01

    To study circulating platelet, monocyte and endothelial microparticles (PMPs, MMPs and EMPs) in patients with antiphospholipid syndrome (APS) in comparison with healthy controls. Fifty-two patients with APS and 52 healthy controls were investigated. MPs were measured on a flow cytometer (Beckman Gallios) and defined as particles sized APS patients versus controls (p APS patients. We observed a high number of EMPs expressing TF in APS patients. The numbers of MMPs and total EMPs were also higher as compared with healthy controls but in contrast to previous reports, the number of PMPs did not differ between groups.

  7. Convective overshooting in stars

    NARCIS (Netherlands)

    Andrássy, R.

    2015-01-01

    Numerous observations provide evidence that the standard picture, in which convective mixing is limited to the unstable layers of a star, is incomplete. The mixing layers in real stars are significantly more extended than what the standard models predict. Some of the observations require changing

  8. Hyperons in neutron stars

    International Nuclear Information System (INIS)

    Glendenning, N.K.

    1986-04-01

    Generalized beta equilibrium involving nucleons, hyperons, and isobars is examined for neutron star matter. The hyperons produce a considerable softening of the equation of state. It is shown that the observed masses of neutron stars can be used to settle a recent controversy concerning the nuclear compressibility. Compressibilities less than 200 MeV are incompatible with observed masses. 7 refs., 9 figs

  9. 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.

  10. Science Through ARts (STAR)

    Science.gov (United States)

    Kolecki, Joseph; Petersen, Ruth; Williams, Lawrence

    2002-01-01

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

  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. Rotating stars in relativity.

    Science.gov (United States)

    Paschalidis, Vasileios; Stergioulas, Nikolaos

    2017-01-01

    Rotating relativistic stars have been studied extensively in recent years, both theoretically and observationally, because of the information they might yield about the equation of state of matter at extremely high densities and because they are considered to be promising sources of gravitational waves. The latest theoretical understanding of rotating stars in relativity is reviewed in this updated article. The sections on equilibrium properties and on nonaxisymmetric oscillations and instabilities in f -modes and r -modes have been updated. Several new sections have been added on equilibria in modified theories of gravity, approximate universal relationships, the one-arm spiral instability, on analytic solutions for the exterior spacetime, rotating stars in LMXBs, rotating strange stars, and on rotating stars in numerical relativity including both hydrodynamic and magnetohydrodynamic studies of these objects.

  13. Dicty_cDB: FC-AP10 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available FC (Link to library) FC-AP10 (Link to dictyBase) - - - Contig-U15819-1 FC-AP10Z (Li...nk to Original site) - - FC-AP10Z 497 - - - - Show FC-AP10 Library FC (Link to library) Clone ID FC-AP10 (Li.../dictycdb.biol.tsukuba.ac.jp/CSM/FC/FC-AP/FC-AP10Q.Seq.d/ Representative seq. ID FC-AP...10Z (Link to Original site) Representative DNA sequence >FC-AP10 (FC-AP10Q) /CSM/FC/FC-AP/FC-AP10Q.Seq....SGDWWDAELKGRRGKVPSNYLQLIKNAAPPRAGGPPVPTGNRA PTTTTTSGGSTRGGFNNGPSTAPSGRGAAPPSSRGGMAPRGGSVAPPSSRGGIAPRGGIA PRGGMAPRGGMAP

  14. Dicty_cDB: FC-AP01 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available FC (Link to library) FC-AP01 (Link to dictyBase) - - - Contig-U15092-1 FC-AP01Z (Li...nk to Original site) - - FC-AP01Z 591 - - - - Show FC-AP01 Library FC (Link to library) Clone ID FC-AP01 (Li.../dictycdb.biol.tsukuba.ac.jp/CSM/FC/FC-AP/FC-AP01Q.Seq.d/ Representative seq. ID FC-AP...01Z (Link to Original site) Representative DNA sequence >FC-AP01 (FC-AP01Q) /CSM/FC/FC-AP/FC-AP01Q.Seq....EELNISGPLSRNKLKWADFLNLTMNTNHARG HRHGRSPSKIFWRAVRGMLPHKTPRGQAALDNMKVFEGVPAPYDKVKRVVVPSALRVVKL NTTRKYTVLSRLSQE

  15. 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.

  16. RELAP5/MOD3 AP600 problems

    International Nuclear Information System (INIS)

    Riemke, R.A.

    1993-01-01

    RELAP5/MOD3 is a reactor systems analysis code that has been developed jointly by the US Nuclear Regulatory Commission (USNRC) and a consortium consisting of several of the countries and domestic organizations that were members of the International Code Assessment and Applications Program (ICAP). The code is currently being used to simulate transients for the next generation of advanced light water reactors (ALWR's). One particular reactor design is the Westinghouse AP600 pressurized water reactor (PWR), which consists of two hot legs and four cold legs as well as passive emergency core cooling (ECC) systems. Initial calculations with RELAP5/MOD3 indicated that the code was not as robust as RELAP5/MOD2.5 with regard to AP600 calculations. Recent modifications in the areas of condensation wall heat transfer, interfacial heat transfer in the presence of noncondensibles, bubbly flow interfacial heat transfer, and time smoothing of both interfacial drag and interfacial heat transfer have improved the robustness, although more reliability is needed

  17. Structural modules in AP1000 plant design

    International Nuclear Information System (INIS)

    Prasad, N.; Tunon-Sanjur, L.

    2007-01-01

    Structural modules are extensively used in AP1000 plant design. The shop manufacturing of modules components improves the quality and reliability of plant structures. The application of modules has a positive impact on construction schedules, and results in substantial savings in the construction cost. This paper describes various types of structural modules used for AP1000 plant structures. CA structural wall modules are steel plate modules with concrete placed, on or within the module, after module installation. The layout and design of the largest CA wall modules, CA01 and CA20, is described in detail. General discussion of structural floor modules, such as the composite and finned floors, is also included. Steel form CB modules (liners) consist of plate reinforced with angle stiffeners and tee sections. The angles and the tee sections are on the concrete side of the plate. Design of CB20 has been included as an example of CB type modules. Design codes and structural concepts related to module designs are discussed. (authors)

  18. On the Mechanisms for Defeating AP Projectiles

    Science.gov (United States)

    Rosenberg, Z.; Dekel, E.; Ashuach, Y.; Yeshurun, Y.

    The important mechanisms for defeating armor piercing (AP) projectiles are reviewed in this paper. These mechanisms are based on the compressive strength of the target material (its inherent resistance to penetration) and on the asymmetrical forces which it exerts on the threat, through proper geometrical arrangements. We discuss the basic features of the resistance to penetration, starting with the classical analysis of the cavity expansion process in elasto-plastic solids. This property of the target is responsible for the deceleration of hard cored projectiles and for the erosion of long rods, under normal impact conditions. We then discuss the asymmetrical interaction of AP projectiles with inclined plates (metals and polymers) and with ceramic spheres. These asymmetric forces are responsible for their deflection and breakup. Our work combines experimental observations with numerical simulations and engineering models, which enhance the understanding of the various phenomena encountered in these complex situations. This understanding is necessary for optimizing the performance of any armor design against a given threat.

  19. AP1000 shield building: a constructability challenge

    International Nuclear Information System (INIS)

    Di Giuseppe, Giovanni; Bonanno, Domenico

    2010-01-01

    The AP1000 Shield Building, an enhanced structure which surrounds the containment vessel, consists of standard Reinforced Concrete (RC) and composite Steel and Concrete (SC) construction. In the SC module the surface steel plates, (with attached shear studs and angles) filled with concrete, act as the steel reinforcement in concrete. This is a relatively new design technology that required the appropriate use of structural codes, supplemented with information from applicable tests on similar composite steel and concrete construction. Being a newer design concept, existing codes do not provide explicit guidance on SC construction so a review of literature and test data on composite structures similar to AP1000 shield building was done in order to confirm the technical basis for the design. The SC walls, air inlet structure and roof of the Shield Building will be constructed using modular construction practices and then transported to site and lifted into place. These modules, working also as permanent form-work, will be filled with high strength Self- Consolidating Concrete. (SCC) This paper provides a focused and integrated presentation of the enhanced shield building design methodology, testing, constructability and inspection. (authors)

  20. 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.

  1. Westinghouse AP1000 advanced passive plant: design features and benefits

    International Nuclear Information System (INIS)

    Walls, S.J.; Cummins, W.E.

    2003-01-01

    The Westinghouse AP1000 Program is aimed at implementing the AP1000 plant to provide a further major improvement in plant economics while maintaining the passive safety advantages established by the AP600. An objective is to retain to the maximum extent possible the plant design of the AP600 so as to retain the licensing basis, cost estimate, construction schedule, modularization scheme, and the detailed design from the AP600 program. Westinghouse and the US Nuclear Regulatory Commission staff have embarked on a program to complete Design Certification for the AP1000 by 2004. A pre-certification review phase was completed in March 2002 and was successful in establishing the applicability of the AP600 test program and AP600 safety analysis codes to the AP1000 Design Certification. On March 28, 2002, Westinghouse submitted to US NRC the AP1000 Design Control Document and Probabilistic Risk Assessment, thereby initiating the formal design certification review process. The results presented in these documents verify the safety performance of the API 000 and conformance with US NRC licensing requirements. Plans are being developed for implementation of a series of AP1000 plants in the US. Key factors in this planning are the economics of AP1000, and the associated business model for licensing, constructing and operating these new plants. Similarly plans are being developed to get the AP1000 design reviewed for use in the UK. Part of this planning has been to examine the AP1000 design relative to anticipated UK safety and licensing issues. (author)

  2. Star Cluster Structure from Hierarchical Star Formation

    Science.gov (United States)

    Grudic, Michael; Hopkins, Philip; Murray, Norman; Lamberts, Astrid; Guszejnov, David; Schmitz, Denise; Boylan-Kolchin, Michael

    2018-01-01

    Young massive star clusters (YMCs) spanning 104-108 M⊙ in mass generally have similar radial surface density profiles, with an outer power-law index typically between -2 and -3. This similarity suggests that they are shaped by scale-free physics at formation. Recent multi-physics MHD simulations of YMC formation have also produced populations of YMCs with this type of surface density profile, allowing us to narrow down the physics necessary to form a YMC with properties as observed. We show that the shallow density profiles of YMCs are a natural result of phase-space mixing that occurs as they assemble from the clumpy, hierarchically-clustered configuration imprinted by the star formation process. We develop physical intuition for this process via analytic arguments and collisionless N-body experiments, elucidating the connection between star formation physics and star cluster structure. This has implications for the early-time structure and evolution of proto-globular clusters, and prospects for simulating their formation in the FIRE cosmological zoom-in simulations.

  3. The magnetic early B-type stars I: magnetometry and rotation

    Science.gov (United States)

    Shultz, M. E.; Wade, G. A.; Rivinius, Th; Neiner, C.; Alecian, E.; Bohlender, D.; Monin, D.; Sikora, J.; MiMeS Collaboration; BinaMIcS Collaboration

    2018-04-01

    The rotational and magnetic properties of many magnetic hot stars are poorly characterized, therefore the Magnetism in Massive Stars and Binarity and Magnetic Interactions in various classes of Stars collaborations have collected extensive high-dispersion spectropolarimetric data sets of these targets. We present longitudinal magnetic field measurements for 52 early B-type stars (B5-B0), with which we attempt to determine their rotational periods Prot. Supplemented with high-resolution spectroscopy, low-resolution Dominion Astrophysical Observatory circular spectropolarimetry, and archival Hipparcos photometry, we determined Prot for 10 stars, leaving only five stars for which Prot could not be determined. Rotational ephemerides for 14 stars were refined via comparison of new to historical magnetic measurements. The distribution of Prot is very similar to that observed for the cooler Ap/Bp stars. We also measured v sin i and vmac for all stars. Comparison to non-magnetic stars shows that v sin i is much lower for magnetic stars, an expected consequence of magnetic braking. We also find evidence that vmac is lower for magnetic stars. Least-squares deconvolution profiles extracted using single-element masks revealed widespread, systematic discrepancies in between different elements: this effect is apparent only for chemically peculiar stars, suggesting it is a consequence of chemical spots. Sinusoidal fits to H line measurements (which should be minimally affected by chemical spots), yielded evidence of surface magnetic fields more complex than simple dipoles in six stars for which this has not previously been reported; however, in all six cases, the second- and third-order amplitudes are small relative to the first-order (dipolar) amplitudes.

  4. Dense Axion Stars.

    Science.gov (United States)

    Braaten, Eric; Mohapatra, Abhishek; Zhang, Hong

    2016-09-16

    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^{-14}M_{⊙} 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^{-20}M_{⊙} 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.

  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. 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.

  7. 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.

  8. 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

  9. The Origin and Evolution of the Galaxy Star Formation Rate-Stellar Mass Correlation

    Science.gov (United States)

    Gawiser, Eric; Iyer, Kartheik

    2018-01-01

    The existence of a tight correlation between galaxies’ star formation rates and stellar masses is far more surprising than usually noted. However, a simple analytical calculation illustrates that the evolution of the normalization of this correlation is driven primarily by the inverse age of the universe, and that the underlying correlation is one between galaxies’ instantaneous star formation rates and their average star formation rates since the Big Bang.Our new Dense Basis method of SED fitting (Iyer & Gawiser 2017, ApJ 838, 127) allows star formation histories (SFHs) to be reconstructed, along with uncertainties, for >10,000 galaxies in the CANDELS and 3D-HST catalogs at 0.5star formation rates, providing new constraints on the level of stochasticity in galaxy formation.

  10. The Nainital Cape Survey Project : A Search for Pulsation in Chemically Peculiar Stars

    Science.gov (United States)

    Chakradhari, Nand Kumar; Joshi, Santosh

    2018-04-01

    The Nainital-Cape Survey is a dedicated search programme initiated in 1999 in the coordination of astronomers from SAAO South Africa, ARIES Nainital and ISRO Bangalore. Over the last 17 years a total of 345 chemically peculiar stars were monitored for photometric variability, making it one of the longest ground-based survey to search for pulsation in chemically peculiar stars in terms of both time span and sample size. Under this survey, we discovered rapid pulsation in the Ap star HD12098 while δ Scuti-type pulsations were detected in seven Am stars. Those stars in which pulsations were not detected have also been tabulated along with their detailed astrophysical parameters for further investigation.

  11. Dicty_cDB: FC-AP22 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available FC (Link to library) FC-AP22 (Link to dictyBase) - G24045 DDB0232387 Contig-U15141-1 FC-AP...22F (Link to Original site) FC-AP22F 317 - - - - - - Show FC-AP22 Library FC (Link to library) Clone ID FC-AP...1-1 Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/FC/FC-AP/FC-AP22Q.Se...q.d/ Representative seq. ID FC-AP22F (Link to Original site) Representative DNA sequence >FC-AP22 (FC-AP22Q) /CSM/FC/FC-AP/FC-AP...KKKKKKK Homology vs CSM-cDNA Score E Sequences producing significant alignments: (bits) Value FC-AP22 (FC-AP22Q) /CSM/FC/FC-AP/FC-AP

  12. Dicty_cDB: FC-AP21 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available FC (Link to library) FC-AP21 (Link to dictyBase) - - - Contig-U15099-1 FC-AP21Z (Li...nk to Original site) - - FC-AP21Z 511 - - - - Show FC-AP21 Library FC (Link to library) Clone ID FC-AP21 (Li.../dictycdb.biol.tsukuba.ac.jp/CSM/FC/FC-AP/FC-AP21Q.Seq.d/ Representative seq. ID FC-AP...21Z (Link to Original site) Representative DNA sequence >FC-AP21 (FC-AP21Q) /CSM/FC/FC-AP/FC-AP21Q.Seq....14Q.Seq.d/ 1013 0.0 SLE553 (SLE553Q) /CSM/SL/SLE5-C/SLE553Q.Seq.d/ 1013 0.0 FC-AP21 (FC-AP21Q) /CSM/FC/FC-AP/FC-AP

  13. Dicty_cDB: FC-AP24 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available FC (Link to library) FC-AP24 (Link to dictyBase) - - - Contig-U16528-1 FC-AP24F (Li...nk to Original site) FC-AP24F 525 - - - - - - Show FC-AP24 Library FC (Link to library) Clone ID FC-AP24 (Li.../dictycdb.biol.tsukuba.ac.jp/CSM/FC/FC-AP/FC-AP24Q.Seq.d/ Representative seq. ID FC-AP...24F (Link to Original site) Representative DNA sequence >FC-AP24 (FC-AP24Q) /CSM/FC/FC-AP/FC-AP24Q.Seq....C-BE24Q.Seq.d/ 1041 0.0 FC-AP24 (FC-AP24Q) /CSM/FC/FC-AP/FC-AP24Q.Seq.d/ 1041 0.0

  14. Control units for APS power supplies

    International Nuclear Information System (INIS)

    Despe, O.D.; Saunders, C.; McGhee, D.G.

    1993-01-01

    The Advanced Photon Source (APS) accelerator facility is made up of five major subsystems in addition to the linac: the positron accumulator ring (PAR), low energy transport (LET), booster synchrotron (SYNCH), high energy transport (HET), the storage ring (SR). Each subsystem has multiple magnet power supply combinations, some requiring multiple of operation. These magnet and power supply combinations computer controlled and monitored. The power supply control unit (PSCU) is the first layer of hardware and software above the power supply itself and is described in this paper. The description includes the basic philosophy for each of operation and how it influences the topology and of implementing control. The design of the analog reference blocks (ARBs) influenced the design of other custom functions well as the feedback controls for vibration and other dynamic corrections. The command set supported by the PSCU is discussed

  15. Investigation of APS PAR Vertical Beam Instability

    CERN Document Server

    Yao, Chihyuan; Sereno, Nicholas S; Yang Bing Xin

    2005-01-01

    The Advanced Photon Source (APS) particle accumulator ring (PAR) is a 325-MeV storage ring that collects and compresses linac pulse trains into a single bunch for booster injection. A vertical beam instability has been observed when only a single linac bunch is injected and the total beam charge is from 0.15 to 0.7 nC. The instability starts about 80 ms after the injection, lasts about 160 ms, and is highly reproducible. We performed spectral measurement and time-resolved imaging with both a gated-intensified camera and a streak camera in order to characterize this instability. Initial analysis of the data indicates that the instability is due to ion trapping. A stable lattice was established as result of the investigation. This report summarizes the experimental results and gives some preliminary analysis.

  16. Carbon Stars T. Lloyd Evans

    Indian Academy of Sciences (India)

    that the features used in estimating luminosities of ordinary giant stars are just those whose abundance ... This difference between the spectral energy distributions (SEDs) of CH stars and the. J stars, which belong to .... that the first group was binaries, as for the CH stars of the solar vicinity, while those of the second group ...

  17. Neutron Stars : Magnetism vs Gravity

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Neutron Stars : Magnetism vs Gravity. WHY do neutron stars have such strong magnetic fields? Conservation of magnetic flux of the collapsing stellar core. ∫ B.ds (over surface of the star) = constant; Radius of the star collapses from ~ 5x108 to 1x104 metres; Hence, ...

  18. Observational Effects of Strange Stars

    OpenAIRE

    Lu, T.

    1998-01-01

    In this talk, after briefly reviewing some historical remarks concerning strange stars, the achievements in physics and dynamical behavior of strange stars are discussed. Especially, various observational effects in distinguishing strange stars from neutron stars such as mechanical effects, cooling effects, phase transition and related interesting phenomena are stressed.

  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. MR imaging during arterial-portography (MR-AP) in the detection of hepatic tumor. Comparison with CT-AP

    International Nuclear Information System (INIS)

    Kajiya, Yoshiki; Nakajo, Masayuki; Miyazono, Nobuaki; Kajiya, Yoriko; Fujiyoshi, Fumito; Ichinari, Naohide

    1997-01-01

    This study was undertaken to compare the detection rate of hepatic space occupying lesion (SOLs) between computed tomography during arterial portography (CT-AP) and magnetic resonance imaging during arterial portography (MR-AP) and the differences in time intensity curve on MR-AP between HCC, metastatic tumor, FNH, and hemangioma. We performed CT-AP and MR-AP in 17 patients including 14 cases of HCC and one each of metastasis, FNH, and hemangioma. MR-AP was performed by Turbo-FLASH sequence. There was no statistically significant difference between CT-AP and MR-AP in detecting satellite lesions in terms of smallest diameter and number of flow defects (p>0.05). Hemangioma showed rapid enhancement after the first pass and, consequently, the same enhancement as the hepatic parenchyma. MR-AP was comparable to CT-AP in the detection of hepatic SOLs. Hemangioma showed an enhancement pattern different from those of HCC, metastatic tumor, and FNH, which showed patterns similar to each other. (author)

  1. Clinical manifestations of antiphospholipid syndrome (APS) with and without antiphospholipid antibodies (the so-called 'seronegative APS').

    Science.gov (United States)

    Rodriguez-Garcia, Jose Luis; Bertolaccini, Maria Laura; Cuadrado, Maria Jose; Sanna, Giovanni; Ateka-Barrutia, Oier; Khamashta, Munther A

    2012-02-01

    Although the medical literature currently provides a growing number of isolated case reports of patients with clinically well-defined antiphospholipid syndrome (APS) and persistently negative antiphospholipid antibodies (aPL), there are no studies including a series of patients addressing the clinical features of this condition. The authors assessed clinical manifestations of APS in 154 patients: 87 patients with seropositive APS and 67 patients with thrombosis and/or pregnancy morbidity persistently negative for aPL and presenting with at least two additional non-criteria manifestations of APS (the so-called 'seronegative APS', SN-APS). Patients were interviewed at the time of recruitment, and a retrospective file review was carried out. There were no significant differences in the frequency of thrombotic events or obstetric morbidity in patients with SN-APS versus patients with seropositive APS: deep vein thrombosis (31.4% vs 31.0%), pulmonary embolism (23.8% vs 28.7%), stroke (14.9% vs 17.2%), transient ischaemic attack (11.9% vs 10.3%), early spontaneous abortions (67.1% vs 52.1%), stillbirths (62.5% vs 59.4%), prematurity (28.1% vs 21.7%) or pre-eclampsia (28.1% vs 23.1%). Classic and SN-APS patients show similar clinical profiles. The results suggest that clinical management in patients with APS should not be based only on the presence of conventional aPL.

  2. Northern star js plaskett

    CERN Document Server

    Broughton, R Peter

    2018-01-01

    Northern Star explores Plaskett's unorthodox and fascinating life from his rural roots near Woodstock through his days as a technician at the University of Toronto to his initiation in astronomy at the Dominion Observatory in Ottawa.

  3. SX Phoenicis stars

    International Nuclear Information System (INIS)

    Nemec, J.; Mateo, M.

    1990-01-01

    The purpose of this paper is to review the basic observational information concerning SX Phe stars, including recent findings such as the discovery of about 40 low-luminosity variable stars in the Carina dwarf galaxy and identification of at least one SX Phe star in the metal-rich globular cluster M71. Direct evidence supporting the hypothesis that at least some BSs are binary systems comes from the discovery of two contact binaries and a semidetached binary among the 50 BSs in the globular cluster NGC 5466. Since these systems will coalesce on a time scale 500 Myr, it stands to reason that many (if not most) BSs are coalesced binaries. The merger hypothesis also explains the relatively-large masses (1.0-1.2 solar masses) that have been derived for SX Phe stars and halo BSs, and may also account for the nonvariable BSs in the 'SX Phe instability strip'. 132 refs

  4. Planets Around Neutron Stars

    Science.gov (United States)

    Wolszczan, Alexander; Kulkarni, Shrinivas R; Anderson, Stuart B.

    2003-01-01

    The objective of this proposal was to continue investigations of neutron star planetary systems in an effort to describe and understand their origin, orbital dynamics, basic physical properties and their relationship to planets around normal stars. This research represents an important element of the process of constraining the physics of planet formation around various types of stars. The research goals of this project included long-term timing measurements of the planets pulsar, PSR B1257+12, to search for more planets around it and to study the dynamics of the whole system, and sensitive searches for millisecond pulsars to detect further examples of old, rapidly spinning neutron stars with planetary systems. The instrumentation used in our project included the 305-m Arecibo antenna with the Penn State Pulsar Machine (PSPM), the 100-m Green Bank Telescope with the Berkeley- Caltech Pulsar Machine (BCPM), and the 100-m Effelsberg and 64-m Parkes telescopes equipped with the observatory supplied backend hardware.

  5. Principles of star formation

    CERN Document Server

    Bodenheimer, Peter H

    2011-01-01

    Understanding star formation is one of the key fields in present-day astrophysics. This book treats a wide variety of the physical processes involved, as well as the main observational discoveries, with key points being discussed in detail. The current star formation in our galaxy is emphasized, because the most detailed observations are available for this case. The book presents a comparison of the various scenarios for star formation, discusses the basic physics underlying each one, and follows in detail the history of a star from its initial state in the interstellar gas to its becoming a condensed object in equilibrium. Both theoretical and observational evidence to support the validity of the general evolutionary path are presented, and methods for comparing the two are emphasized. The author is a recognized expert in calculations of the evolution of protostars, the structure and evolution of disks, and stellar evolution in general. This book will be of value to graduate students in astronomy and astroph...

  6. Radiation characteristics of scintillator coupled CMOS APS for radiography conditions

    International Nuclear Information System (INIS)

    Kim, Kwang Hyun; Kim, Soongpyung; Kang, Dong-Won; Kim, Dong-Kie

    2006-01-01

    Under industrial radiography conditions, we analyzed short-term radiation characteristics of scintillator coupled CMOS APS (hereinafter SC CMOS APS). By means of experimentation, the contribution of the transmitted X-ray through the scintillator to the properties of the CMOS APS and the afterimage, generated in the acquired image even at low dose condition, were investigated. To see the transmitted X-ray effects on the CMOS APS, Fein focus TM X-ray machine, two scintillators of Lanex TM Fine and Regular, and two CMOS APS array of RadEye TM were used under the conditions of 50 kV p /1 mAs and 100 kV p /1 mAs. By measuring the transmitted X-ray on signal and Noise Power Spectrum, we analytically examined the generation mechanism of the afterimage, based on dark signal or dark current increase in the sensor, and explained the afterimage in the SC CMOS APS

  7. Recent highlights from STAR

    Science.gov (United States)

    Zha, Wangmei

    2018-02-01

    The Solenoidal Tracker at RHIC (STAR) experiment takes advantage of its excellent tracking and particle identification capabilities at mid-rapidity to explore the properties of strongly interacting QCD matter created in heavy-ion collisions at RHIC. The STAR collaboration presented 7 parallel and 2 plenary talks at Strangeness in Quark Matter 2017 and covered various topics including heavy flavor measurements, bulk observables, electro-magnetic probes and the upgrade program. This paper highlights some of the selected results.

  8. Star of Bethlehem

    Science.gov (United States)

    Hughes, D.; Murdin, P.

    2001-07-01

    The biblical Star of Bethlehem, which heralded the birth of Jesus Christ, is only mentioned in the Gospel of St Matthew 2. The astrologically significant 7 bc triple conjunction of Jupiter and Saturn in the constellation of Pisces is the most likely candidate, although a comet/nova in 5 bc and a comet in 4 bc cannot be ruled out. There is also the possibility that the star was simply fictitious....

  9. Auricular Chondritis in a Postpartum Flare of SLE and APS

    Directory of Open Access Journals (Sweden)

    Elodie Ponce

    2014-10-01

    Full Text Available Introduction: Auricular chondritis has been occasionally described in patients with systemic lupus erythematosus (SLE and antiphospholipid syndrome (APS. Materials and methods: We report the case of a woman with a previous history of APS who presented with auricular chondritis with onset of SLE symptoms during the postpartum period. Conclusion: SLE and APS should be taken into consideration in the differential diagnosis of auricular chondritis.

  10. Essence and characteristics of the Westinghouse technology AP1000

    International Nuclear Information System (INIS)

    Llovet, Ricardo

    2014-01-01

    The AP1000 nuclear power plant can place the reactor in a Safe Shutdown Condition within the first 72 hours of a Station Blackout, without the use of AC power or operator action •With some operator action after 3 days, the AP1000 nuclear power plant continues to maintain reactor core cooling and Spent Fuel Pool cooling indefinitely •The AP1000 nuclear power plant has superior coping capabilities as well as significantly reduced risk for core damage

  11. FRANX. Application for analysis and quantification of the APS fire

    International Nuclear Information System (INIS)

    Snchez, A.; Osorio, F.; Ontoso, N.

    2014-01-01

    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)

  12. AP-2ε Expression in Developing Retina: Contributing to the Molecular Diversity of Amacrine Cells.

    Science.gov (United States)

    Jain, Saket; Glubrecht, Darryl D; Germain, Devon R; Moser, Markus; Godbout, Roseline

    2018-02-21

    AP-2 transcription factors play important roles in the regulation of gene expression during development. Four of the five members of the AP-2 family (AP-2α, AP-2β, AP-2γ and AP-2δ) have previously been shown to be expressed in developing retina. Mouse knockouts have revealed roles for AP-2α, AP-2β and AP-2δ in retinal cell specification and function. Here, we show that the fifth member of the AP-2 family, AP-2ε, is also expressed in amacrine cells in developing mammalian and chicken retina. Our data indicate that there are considerably fewer AP-2ε-positive cells in the developing mouse retina compared to AP-2α, AP-2β and AP-2γ-positive cells, suggesting a specialized role for AP-2ε in a subset of amacrine cells. AP-2ε, which is restricted to the GABAergic amacrine lineage, is most commonly co-expressed with AP-2α and AP-2β, especially at early stages of retinal development. Co-expression of AP-2ε and AP-2γ increases with differentiation. Analysis of previously published Drop-seq data from single retinal cells supports co-expression of multiple AP-2s in the same cell. Since AP-2s bind to their target sequences as either homodimers or heterodimers, our work suggests spatially- and temporally-coordinated roles for combinations of AP-2 transcription factors in amacrine cells during retinal development.

  13. Young Stars with SALT

    Energy Technology Data Exchange (ETDEWEB)

    Riedel, Adric R. [Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Alam, Munazza K.; Rice, Emily L.; Cruz, Kelle L. [Department of Astrophysics, The American Museum of Natural History, New York, NY 10024 (United States); Henry, Todd J., E-mail: arr@caltech.edu [RECONS Institute, Chambersburg, PA (United States)

    2017-05-10

    We present a spectroscopic and kinematic analysis of 79 nearby M dwarfs in 77 systems. All of these dwarfs 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 on the South African Large Telescope, we have determined radial velocities, H-alpha, lithium 6708 Å, and potassium 7699 Å equivalent widths linked to age and activity, and spectral types for all of our targets. Combined with astrometric information from literature sources, we identify 44 young stars. Eighteen are previously known members of moving groups within 100 pc of the Sun. Twelve are new members, including one member of the TW Hydra moving group, one member of the 32 Orionis moving group, 9 members of Tucana-Horologium, one member of Argus, and two new members of AB Doradus. We also find 14 young star systems that are not members of any known groups. The remaining 33 star systems do not appear to be young. This appears to be evidence of a new population of nearby young stars not related to the known nearby young moving groups.

  14. Young Stars with SALT

    Science.gov (United States)

    Riedel, Adric R.; Alam, Munazza K.; Rice, Emily L.; Cruz, Kelle L.; Henry, Todd J.

    2017-05-01

    We present a spectroscopic and kinematic analysis of 79 nearby M dwarfs in 77 systems. All of these dwarfs 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 on the South African Large Telescope, we have determined radial velocities, H-alpha, lithium 6708 Å, and potassium 7699 Å equivalent widths linked to age and activity, and spectral types for all of our targets. Combined with astrometric information from literature sources, we identify 44 young stars. Eighteen are previously known members of moving groups within 100 pc of the Sun. Twelve are new members, including one member of the TW Hydra moving group, one member of the 32 Orionis moving group, 9 members of Tucana-Horologium, one member of Argus, and two new members of AB Doradus. We also find 14 young star systems that are not members of any known groups. The remaining 33 star systems do not appear to be young. This appears to be evidence of a new population of nearby young stars not related to the known nearby young moving groups. Based on observations made with the Southern African Large Telescope (SALT).

  15. Massive star evolution

    International Nuclear Information System (INIS)

    Varshavskij, V.I.; Tutukov, A.V.; AN SSSR, Moscow. Astronomicheskij Sovet)

    1975-01-01

    The structure and evolution of 16 (Sun mass), 32 (Sun mass), and 64 (Sun mass) stars with the initial chemical composition X=0.602, Y=0.354, and Z=0.044 (X 12 = 0.00619 and X 16 = 0.01847) are analyzed from the initial main sequence to a complete burnup of oxygen in the nucleus of a red supergiant. At the stage of helium buring in the nucleus the evolutionary track of the star is determined by the equilibrium condition in the zone of varying chemical composition, and at later stages by energy losses due to neutrino emission. In the absence of neutrino emission the external convective zone propagates into regions occupied by the former hydrogen and helium layer sources. This may lead to considerable anomalies in the chemical composition at the star surface and to the decrease of the carbon-oxygen nucleus mass. With regard to neutrino energy losses the structure of layer sources and of the star itself becomes more complicated, thereby increasing the evolution time. Estimation is made of the change in heli.um, carbon, and oxygen contents in the interstellar space over the Galaxy's lifetime as a result of the evolution of massive stars. Some consequences of rotation and meridional circulations are discussed. A study of the structure and evolution of hydrogen-helium massive stars before firing of carbon in the nucleus is made

  16. ONLINE MINIMIZATION OF VERTICAL BEAM SIZES AT APS

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yipeng

    2017-06-25

    In this paper, online minimization of vertical beam sizes along the APS (Advanced Photon Source) storage ring is presented. A genetic algorithm (GA) was developed and employed for the online optimization in the APS storage ring. A total of 59 families of skew quadrupole magnets were employed as knobs to adjust the coupling and the vertical dispersion in the APS storage ring. Starting from initially zero current skew quadrupoles, small vertical beam sizes along the APS storage ring were achieved in a short optimization time of one hour. The optimization results from this method are briefly compared with the one from LOCO (Linear Optics from Closed Orbits) response matrix correction.

  17. The Ped-APS Registry: the antiphospholipid syndrome in childhood.

    Science.gov (United States)

    Avcin, T; Cimaz, R; Rozman, B

    2009-09-01

    In recent years, antiphospholipid syndrome (APS) has been increasingly recognised in various paediatric autoimmune and nonautoimmune diseases, but the relatively low prevalence and heterogeneity of APS in childhood made it very difficult to study in a systematic way. The project of an international registry of paediatric patients with APS (the Ped-APS Registry) was initiated in 2004 to foster and conduct multicentre, controlled studies with large number of paediatric APS patients. The Ped-APS Registry is organised as a collaborative project of the European Forum on Antiphospholipid Antibodies and Juvenile Systemic Lupus Erythematosus Working Group of the Paediatric Rheumatology European Society. Currently, it documents a standardised clinical, laboratory and therapeutic data of 133 children with antiphospholipid antibodies (aPL)-related thrombosis from 14 countries. The priority projects for future research of the Ped-APS Registry include prospective enrollment of new patients with aPL-related thrombosis, assessment of differences between the paediatric and adult APS, evaluation of proinflammatory genotype as a risk factor for APS manifestations in childhood and evaluation of patients with isolated nonthrombotic aPL-related manifestations.

  18. 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.

  19. Dicty_cDB: FC-AP13 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available FC (Link to library) FC-AP13 (Link to dictyBase) - - - Contig-U15374-1 FC-AP13P (Li...nk to Original site) FC-AP13F 550 FC-AP13Z 184 FC-AP13P 734 - - Show FC-AP13 Library FC (Link to library) Clone ID FC-AP...al site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/FC/FC-AP/FC-AP13Q.Seq.d/ Representative seq. ID FC-AP...13P (Link to Original site) Representative DNA sequence >FC-AP13 (FC-AP13Q) /CSM/FC/FC-AP/FC-AP...KKRKLNILIIII*fnnhqvmekkikkkiknkkn f*k Homology vs CSM-cDNA Score E Sequences producing significant alignments: (bits) Value FC-AP

  20. 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.

  1. AIRE variations in Addison's disease and autoimmune polyendocrine syndromes (APS): partial gene deletions contribute to APS I.

    Science.gov (United States)

    Bøe Wolff, A S; Oftedal, B; Johansson, S; Bruland, O; Løvås, K; Meager, A; Pedersen, C; Husebye, E S; Knappskog, P M

    2008-03-01

    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 of the AIRE gene covering at least exon 2 to exon 8. We conclude that polymorphisms in the AIRE gene are not associated with AAD and APS II. We further suggest that DNA analysis of the parents of patients found to be homozygous for mutations in AIRE, always should be performed.

  2. Nuclear Phosphatidylinositol-Phosphate Type I Kinase α-Coupled Star-PAP Polyadenylation Regulates Cell Invasion.

    Science.gov (United States)

    A P, Sudheesh; Laishram, Rakesh S

    2018-03-01

    Star-PAP, a nuclear phosphatidylinositol (PI) signal-regulated poly(A) polymerase (PAP), couples with type I PI phosphate kinase α (PIPKIα) and controls gene expression. We show that Star-PAP and PIPKIα together regulate 3'-end processing and expression of pre-mRNAs encoding key anti-invasive factors ( KISS1R , CDH1 , NME1 , CDH13 , FEZ1 , and WIF1 ) in breast cancer. Consistently, the endogenous Star-PAP level is negatively correlated with the cellular invasiveness of breast cancer cells. While silencing Star-PAP or PIPKIα increases cellular invasiveness in low-invasiveness MCF7 cells, Star-PAP overexpression decreases invasiveness in highly invasive MDA-MB-231 cells in a cellular Star-PAP level-dependent manner. However, expression of the PIPKIα-noninteracting Star-PAP mutant or the phosphodeficient Star-PAP (S6A mutant) has no effect on cellular invasiveness. These results strongly indicate that PIPKIα interaction and Star-PAP S6 phosphorylation are required for Star-PAP-mediated regulation of cancer cell invasion and give specificity to target anti-invasive gene expression. Our study establishes Star-PAP-PIPKIα-mediated 3'-end processing as a key anti-invasive mechanism in breast cancer. Copyright © 2018 A.P. and Laishram.

  3. High Pressure Reverse Flow APS Engine

    Science.gov (United States)

    Senneff, J. M.

    1972-01-01

    A design and test demonstration effort was undertaken to evaluate the concept of the reverse flow engine for the APS engine application. The 1500 lb (6672 N) thrust engine was designed to operate on gaseous hydrogen and gaseous oxygen propellants at a mixture ratio of 4 and to achieve the objective performance of 435 sec (4266 Nsec/kg) specific impulse. Superimposed durability requirements called for a million-cycle capability with 50 hours duration. The program was undertaken as a series of tasks including the initial preliminary design, design of critical test components and finally, the design and demonstration of an altitude engine which could be used interchangeably to examine operating parameters as well as to demonstrate the capability of the concept. The program results are reported with data to indicate that all of the program objectives were met or exceeded within the course of testing on the program. The analysis effort undertaken is also reported in detail and supplemented with test data in some cases where prior definitions could not be made. The results are contained of these analyses as well as the test results conducted throughout the course of the program. Finally, the test data and analytical results were combined to allow recommendations for a flight weight design. This preliminary design effort is also detailed.

  4. 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.

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

    International Nuclear Information System (INIS)

    RIECK, C.A.

    1999-01-01

    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

  6. Hyperoxia increases AP-1 DNA binding in rat brain.

    Science.gov (United States)

    Tong, LiQi; Toliver-Kinsky, Tracy; Rassin, David; Werrbach-Perez, Karin; Perez-Polo, J Regino

    2003-01-01

    Oxidative stress appears to contribute to neurodegenerative outcomes after ischemia, hypoxia, and hyperoxia. The AP-1 transcription factor is made up of a family of regulatory proteins that can be activated by oxidative stress. In the present study, we examined AP-1 DNA binding activity in terms of specific participating AP-1 proteins in rat brain after hyperoxia. Male Sprague-Dawley rats were exposed to 100% oxygen under isobaric conditions over time. The AP-1 DNA binding activity present in the rat hippocampus and basal forebrain was characterized by electrophoretic mobility shift analysis (EMSA) and the participating AP-1 proteins identified by immunodepletion/supershift and Western blotting analyses. The Fos and Jun proteins were localized by immunohistochemistry to hippocampus. There were significant increases in AP-1 DNA binding in both hippocampus and basal forebrain after hyperoxia. There was also a significant increase in c-Jun protein levels and the proportion of c-Jun present in AP-1 DNA binding complexes in hippocampal nuclei after hyperoxia. These results suggest that AP-1 activation via c-Jun binding to DNA is an important component of brain responses to oxidative stress.

  7. Training and development of the Assistant Practitioners (APs) in radiography

    International Nuclear Information System (INIS)

    Stewart-Lord, Adéle

    2014-01-01

    A mixed methods study conducted over three phases (Phase I – scoping exercise, Phase II – questionnaire and Phase III – semi-structured interviews) aimed to explore the role and integration of the assistant practitioner (AP) practitioner in radiography from the AP perspective. Findings of the overall study are presented across a range of articles where this publication only presents the findings in relation to the training and education of APs from all three phases. Results showed the educational routes undertaken by APs in radiography during training. Training whilst working in the clinical department has highlighted a number of key issues relating to educational pathways and delivery methods. Findings showed that APs felt that more could be done to prepare the individual for clinical practice thereby increasing their confidence and facilitating role development. Results also identified a number of challenges in the training and education of APs in radiography. Clear routes of progression and career pathways are not available to APs in radiography. In conclusion the findings suggest the need for a review of existing educational programmes and future standardisation. The need exists to clarify the justifiable methods of training and differentiate between recognised educational qualifications to enable informed career development decisions by APs and their employers

  8. Discussion of QA grading for AP1000 NP plant

    International Nuclear Information System (INIS)

    Luo Shuiyun; Zhang Qingchuan

    2012-01-01

    The grading method of quality assurance for the following AP1000 project is presented based on the Westinghouse classification principle, referring to the classification method of the AP1000 self-reliance supporting project and considering the factors of classification, which can meet the requirements of domestic nuclear safety regulation and standard of the QA classification. (authors)

  9. Status of the Advanced Photon Source (APS) linear accelerator

    International Nuclear Information System (INIS)

    White, M.; Berg, W.; Fuja, R.; Grelick, A.; Mavrogenes, G.; Nassiri, A.; Russell, T.; Wesolowski, W.

    1993-01-01

    A 2856-MHz S-band, 450-MeV electron/positron linear accelerator is the first part of the injector for the Advanced Photon Source (APS) 7-GeV storage ring. Construction of the APS linac is currently nearing completion, and commissioning will begin in July 1993. The linac and its current status are discussed in this paper

  10. Data-Based Decision Making: The Road to AP Equity

    Science.gov (United States)

    Edwards, Kelcey; Duggan, Odette

    2012-01-01

    Presented at the Advanced Placement Annual Conference (APAC) in Lake Buena Vista, FL in July 2012. This presentation reviews concepts central to achieving equitable AP access and success for all willing and academically prepared students. We analyze trends in participation and performance by race/ethnicity from the AP Report to the Nation and…

  11. 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)

  12. [Diverse histological lesions in a patient with antiphospholipid syndrome (APS)].

    Science.gov (United States)

    Salvatore, Ermanno; Luciani, Remo; Di Palma, Annamaria; Aversano, Arturo; Stellato, Davide; Liuzzi, Marco; Iele, Emilio; Martignetti, Vinicio; Spagnuolo, Enrico; Morrone, Luigi

    2011-01-01

    Antiphospholipid syndrome (APS) is a rare autoimmune disorder. It can be secondary to systemic lupus erythematosus (SLE) or occur in the absence of autoimmune disease. The hallmark of this so-called primary APS is the presence of circulating antiphospholipid antibodies. Renal involvement in primary APS is caused by thrombosis within the renal vasculature. Recently, nonthrombotic glomerulonephritic renal lesions have been described in primary APS as a new histological entity. We here report a patient with primary APS in whom both lesion types were present. A 58-year-old Caucasian man with no significant past medical history presented to our nephrology unit with diffuse edema. Urinalysis showed proteinuria exceeding 400 mg/dL. The autoantibody panel (p-ANCA, c- ANCA, anti-nucleus, anti-DS-DNA) was negative except for anticardiolipin antibodies, which tested positive in two different samples. The diagnostic workup included a kidney biopsy that revealed thrombotic lesions compatible with primary APS and a typical pattern of focal segmental glomerulosclerosis. The kidney is a major target in APS but the exact mechanism underlying the pathogenesis of APS nephropathy has been poorly recognized. The use of kidney biopsy is a fundamental diagnostic tool in this setting, with possible implications also from a prognostic and therapeutic viewpoint.

  13. Building an SDN enterprise WLAN based on virtual APs

    NARCIS (Netherlands)

    Sequeira, L.; Cruz, J.L. de la; Ruiz-Mas, J.; Saldana, J.; Fernandez-Navajas, J.; Almodovar, J.

    2017-01-01

    In this letter, the development and testing of an open enterprise Wi-Fi solution based on virtual access points (APs), managed by a central WLAN controller is presented. It allows seamless handovers between APs in different channels, maintaining the QoS of real-time services. The potential

  14. OpenAPS Data Commons on Open Humans

    OpenAIRE

    Lewis, Dana M.; Ball, Madeleine

    2017-01-01

    Poster describing OpenAPS, Open Humans, and joint work creating a data commons for OpenAPS data in the Open Humans platform. Presented at the 2017 Sage Assembly Bionetworks Assembly and recipient of a Young Innovator/Investigator award.

  15. AP: A Critical Examination of the Advanced Placement Program

    Science.gov (United States)

    Sadler, Philip M.; Sonnert, Gerhard; Tai, Robert; Klopfenstein, Kirstin

    2016-01-01

    The Advanced Placement (AP) program was created to enhance the experience of gifted students as they transition from high school to college. "AP: A Critical Examination of the Advanced Placement Program," edited by Philip M. Sadler, Gerhard Sonnert, Robert Tai, and Kirstin Klopfenstein (2010, Harvard Education Press), questions the…

  16. A Closer Examination of the Academic Benefits of AP

    Science.gov (United States)

    McKillip, Mary E. M.; Rawls, Anita

    2013-01-01

    The authors sought to better understand the relationship between students participating in the Advanced Placement (AP) program and subsequent performance on the Scholastic Aptitude Test (SAT). Focusing on students graduating from U.S. public high schools in 2010, the authors used propensity scores to match junior year AP examinees in 3 subjects to…

  17. Development of a superconducting undulator for the APS

    International Nuclear Information System (INIS)

    Ivanyushenkov, Y; Abliz, M; Doose, C; Fuerst, J; Hasse, Q; Kasa, M; Trakhtenberg, E; Vasserman, I; Gluskin, E; Lev, V; Mezentsev, N; Syrovatin, V; Tsukanov, V

    2013-01-01

    As the western hemisphere's premier x-ray synchrotron radiation source, the Advanced Photon Source (APS) continues to advance the state of the art in insertion device technology in order to maintain record high brightness, especially in the hard x-ray wavelength region. Due to the unique bunch pattern used for normal APS operations and its ultimate capabilities, the APS has chosen superconducting technology for its future hard x-ray undulator sources. In the last several years, the APS in collaboration with the Budker Institute of Nuclear Physics has being developing the technology for planar, small-period superconducting undulators (SCUs). These developments include the design and construction of several prototypes and the construction of the necessary mechanical, vacuum, and cryogenic infrastructure at the APS site. Several prototypes of the SCU magnetic structure have been built and tested. The first SCU is assembled and will be installed in the APS storage ring at the end of 2012. Expected SCU performance in terms of x-ray brightness should noticeably exceed that of existing APS undulators. Immediately after commissioning, the SCU will be used at APS Sector 6 as the radiation source for high-energy x-ray studies.

  18. AP@home: The Artificial Pancreas Is Now at Home

    NARCIS (Netherlands)

    Heinemann, Lutz; Benesch, Carsten; DeVries, J. Hans

    2016-01-01

    In the past years the development of an artificial pancreas (AP) has made great progress and many activities are ongoing in this area of research. The major step forward made in the last years was moving the evaluation of AP systems from highly controlled experimental conditions to daily life

  19. 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.

  20. Lithium in LMC carbon stars

    OpenAIRE

    Hatzidimitriou, D.; Morgan, D. H.; Cannon, R. D.; Croke, B. F. W.

    2003-01-01

    Nineteen carbon stars that show lithium enrichment in their atmospheres have been discovered among a sample of 674 carbon stars in the Large Magellanic Cloud. Six of the Li-rich carbon stars are of J-type, i.e. with strong 13C isotopic features. No super-Li-rich carbon stars were found. The incidence of lithium enrichment among carbon stars in the LMC is much rarer than in the Galaxy, and about five times more frequent among J-type than among N-type carbon stars. The bolometric magnitudes of ...

  1. The development of beam current monitors in the APS

    International Nuclear Information System (INIS)

    Wang, X.; Lenkszus, F.; Rotela, E.

    1995-01-01

    The Advanced Photon Source (APS) is a third-generation 7-GeV synchrotron radiation source. The precision measurement of beam current is a challenging task in high energy accelerators, such as the APS, with a wide range of beam parameters and complicated noise, radiation, and thermal environments. The beam pulses in the APS injector and storage ring have charge ranging from 50pC to 25nC with pulse durations varying from 30ps to 30ns. A total of nine non- intercepting beam current monitors have been installed in the APS facility (excluding those in the linac) for general current measurement. In addition, several independent current monitors with specially designed redundant interlock electronics are installed for personnel safety and machine protection. This paper documents the design and development of current monitors in the APS,. discusses the commissioning experience in the past year, and presents the results of recent operations

  2. AP1000, a nuclear central of advanced design

    International Nuclear Information System (INIS)

    Hernandez M, N.; Viais J, J.

    2005-01-01

    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)

  3. Maintenance of the APS of an electron beam accelerator

    International Nuclear Information System (INIS)

    Lee, Byung Cheol; Choi, Hwa Lim; Yang, Ki Ho; Kim, Sung Chan

    2008-12-01

    APS is a part of power supply system which provides the high voltage, high current to the anode of electron beam in the irradiation facility in KAERI. This APS had been used in turn-key base for 10 years, and frequently the Russian scientists had visited to repair this machine. In Summer the humid air had been supplied to dissipate the heat of APS. There is a big and high frequency noise around the transformer in the mutation room. So we stopped the irradiation works and analyzed and repaired the APS. The main course of the problem is the deterioration of IGBT and thyristors which are components of phase controller. We replaced this by new one and APS is now operating well

  4. Dynamical Boson Stars

    Directory of Open Access Journals (Sweden)

    Steven L. Liebling

    2012-05-01

    Full Text Available The idea of stable, localized bundles of energy has strong appeal as a model for particles. In the 1950s, John Wheeler envisioned such bundles as smooth configurations of electromagnetic energy that he called geons, but none were found. Instead, particle-like solutions were found in the late 1960s with the addition of a scalar field, and these were given the name boson stars. Since then, boson stars find use in a wide variety of models as sources of dark matter, as black hole mimickers, in simple models of binary systems, and as a tool in finding black holes in higher dimensions with only a single Killing vector. We discuss important varieties of boson stars, their dynamic properties, and some of their uses, concentrating on recent efforts.

  5. Instability and star evolution

    International Nuclear Information System (INIS)

    Mirzoyan, L.V.

    1981-01-01

    The observational data are discussed which testify that the phenomena of dynamical instability of stars and stellar systems are definite manifestations of their evolution. The study of these phenomena has shown that the instability is a regular phase of stellar evolution. It has resulted in the recognition of the most important regularities of the process of star formation concerning its nature. This became possible due to the discovery in 1947 of stellar associations in our Galaxy. The results of the study of the dynamical instability of stellar associations contradict the predictions of classical hypothesis of stellar condensation. These data supplied a basis for a new hypothesis on the formation of stars and nebulae by the decay of superdense protostars [ru

  6. Atomic diffusion in stars

    CERN Document Server

    Michaud, Georges; Richer, Jacques

    2015-01-01

    This book gives an overview of atomic diffusion, a fundamental physical process, as applied to all types of stars, from the main sequence to neutron stars. The superficial abundances of stars as well as their evolution can be significantly affected. The authors show where atomic diffusion plays an essential role and how it can be implemented in modelling.  In Part I, the authors describe the tools that are required to include atomic diffusion in models of stellar interiors and atmospheres. An important role is played by the gradient of partial radiative pressure, or radiative acceleration, which is usually neglected in stellar evolution. In Part II, the authors systematically review the contribution of atomic diffusion to each evolutionary step. The dominant effects of atomic diffusion are accompanied by more subtle effects on a large number of structural properties throughout evolution. One of the goals of this book is to provide the means for the astrophysicist or graduate student to evaluate the importanc...

  7. The twinkling of stars

    International Nuclear Information System (INIS)

    Jakeman, E.; Parry, G.; Pike, E.R.; Pusey, P.N.

    1978-01-01

    This article collects together some of the main ideas and experimental results on the twinkling of stars. Statistical methods are used to characterise the features of the scintillation and to investigate the ways in which these depend on the zenith angle of the star, the bandwidth of the light and various other parameters. Some new results are included which demonstrate the advantages of using photon counting methods in experiments on stellar scintillation. Since the twinkling of stars is a consequence of the turbulence in the Earth's magnetic atmosphere then measurements can be used to deduce some features of the structure of the turbulence. Some of the experiments designed to do this are discussed and the results reported. (author)

  8. Pulsating Star Mystery Solved

    Science.gov (United States)

    2010-11-01

    By discovering the first double star where a pulsating Cepheid variable and another star pass in front of one another, an international team of astronomers has solved a decades-old mystery. The rare alignment of the orbits of the two stars in the double star system has allowed a measurement of the Cepheid mass with unprecedented accuracy. Up to now astronomers had two incompatible theoretical predictions of Cepheid masses. The new result shows that the prediction from stellar pulsation theory is spot on, while the prediction from stellar evolution theory is at odds with the new observations. The new results, from a team led by Grzegorz Pietrzyński (Universidad de Concepción, Chile, Obserwatorium Astronomiczne Uniwersytetu Warszawskiego, Poland), appear in the 25 November 2010 edition of the journal Nature. Grzegorz Pietrzyński introduces this remarkable result: "By using the HARPS instrument on the 3.6-metre telescope at ESO's La Silla Observatory in Chile, along with other telescopes, we have measured the mass of a Cepheid with an accuracy far greater than any earlier estimates. This new result allows us to immediately see which of the two competing theories predicting the masses of Cepheids is correct." Classical Cepheid Variables, usually called just Cepheids, are unstable stars that are larger and much brighter than the Sun [1]. They expand and contract in a regular way, taking anything from a few days to months to complete the cycle. The time taken to brighten and grow fainter again is longer for stars that are more luminous and shorter for the dimmer ones. This remarkably precise relationship makes the study of Cepheids one of the most effective ways to measure the distances to nearby galaxies and from there to map out the scale of the whole Universe [2]. Unfortunately, despite their importance, Cepheids are not fully understood. Predictions of their masses derived from the theory of pulsating stars are 20-30% less than predictions from the theory of the

  9. General Relativity&Compact Stars

    Energy Technology Data Exchange (ETDEWEB)

    Glendenning, Norman K.

    2005-08-16

    Compact stars--broadly grouped as neutron stars and white dwarfs--are the ashes of luminous stars. One or the other is the fate that awaits the cores of most stars after a lifetime of tens to thousands of millions of years. Whichever of these objects is formed at the end of the life of a particular luminous star, the compact object will live in many respects unchanged from the state in which it was formed. Neutron stars themselves can take several forms--hyperon, hybrid, or strange quark star. Likewise white dwarfs take different forms though only in the dominant nuclear species. A black hole is probably the fate of the most massive stars, an inaccessible region of spacetime into which the entire star, ashes and all, falls at the end of the luminous phase. Neutron stars are the smallest, densest stars known. Like all stars, neutron stars rotate--some as many as a few hundred times a second. A star rotating at such a rate will experience an enormous centrifugal force that must be balanced by gravity or else it will be ripped apart. The balance of the two forces informs us of the lower limit on the stellar density. Neutron stars are 10{sup 14} times denser than Earth. Some neutron stars are in binary orbit with a companion. Application of orbital mechanics allows an assessment of masses in some cases. The mass of a neutron star is typically 1.5 solar masses. They can therefore infer their radii: about ten kilometers. Into such a small object, the entire mass of our sun and more, is compressed.

  10. General Relativity and Compact Stars

    International Nuclear Information System (INIS)

    Glendenning, Norman K.

    2005-01-01

    Compact stars--broadly grouped as neutron stars and white dwarfs--are the ashes of luminous stars. One or the other is the fate that awaits the cores of most stars after a lifetime of tens to thousands of millions of years. Whichever of these objects is formed at the end of the life of a particular luminous star, the compact object will live in many respects unchanged from the state in which it was formed. Neutron stars themselves can take several forms--hyperon, hybrid, or strange quark star. Likewise white dwarfs take different forms though only in the dominant nuclear species. A black hole is probably the fate of the most massive stars, an inaccessible region of spacetime into which the entire star, ashes and all, falls at the end of the luminous phase. Neutron stars are the smallest, densest stars known. Like all stars, neutron stars rotate--some as many as a few hundred times a second. A star rotating at such a rate will experience an enormous centrifugal force that must be balanced by gravity or else it will be ripped apart. The balance of the two forces informs us of the lower limit on the stellar density. Neutron stars are 10 14 times denser than Earth. Some neutron stars are in binary orbit with a companion. Application of orbital mechanics allows an assessment of masses in some cases. The mass of a neutron star is typically 1.5 solar masses. They can therefore infer their radii: about ten kilometers. Into such a small object, the entire mass of our sun and more, is compressed

  11. Chaplygin dark star

    International Nuclear Information System (INIS)

    Bertolami, O.; Paramos, J.

    2005-01-01

    We study the general properties of a spherically symmetric body described through the generalized Chaplygin equation of state. We conclude that such an object, dubbed generalized Chaplygin dark star, should exist within the context of the generalized Chaplygin gas (GCG) model of unification of dark energy and dark matter, and derive expressions for its size and expansion velocity. A criteria for the survival of the perturbations in the GCG background that give origin to the dark star are developed, and its main features are analyzed

  12. The formation of stars

    CERN Document Server

    Stahler, Steven W

    2008-01-01

    This book is a comprehensive treatment of star formation, one of the most active fields of modern astronomy. The reader is guided through the subject in a logically compelling manner. Starting from a general description of stars and interstellar clouds, the authors delineate the earliest phases of stellar evolution. They discuss formation activity not only in the Milky Way, but also in other galaxies, both now and in the remote past. Theory and observation are thoroughly integrated, with the aid of numerous figures and images. In summary, this volume is an invaluable resource, both as a text f

  13. Synthetic guide star generation

    Science.gov (United States)

    Payne, Stephen A [Castro Valley, CA; Page, Ralph H [Castro Valley, CA; Ebbers, Christopher A [Livermore, CA; Beach, Raymond J [Livermore, CA

    2008-06-10

    A system for assisting in observing a celestial object and providing synthetic guide star generation. A lasing system provides radiation at a frequency at or near 938 nm and radiation at a frequency at or near 1583 nm. The lasing system includes a fiber laser operating between 880 nm and 960 nm and a fiber laser operating between 1524 nm and 1650 nm. A frequency-conversion system mixes the radiation and generates light at a frequency at or near 589 nm. A system directs the light at a frequency at or near 589 nm toward the celestial object and provides synthetic guide star generation.

  14. The Drifting Star

    Science.gov (United States)

    2008-04-01

    By studying in great detail the 'ringing' of a planet-harbouring star, a team of astronomers using ESO's 3.6-m telescope have shown that it must have drifted away from the metal-rich Hyades cluster. This discovery has implications for theories of star and planet formation, and for the dynamics of our Milky Way. ESO PR Photo 09a/08 ESO PR Photo 09a/08 Iota Horologii The yellow-orange star Iota Horologii, located 56 light-years away towards the southern Horologium ("The Clock") constellation, belongs to the so-called "Hyades stream", a large number of stars that move in the same direction. Previously, astronomers using an ESO telescope had shown that the star harbours a planet, more than 2 times as large as Jupiter and orbiting in 320 days (ESO 12/99). But until now, all studies were unable to pinpoint the exact characteristics of the star, and hence to understand its origin. A team of astronomers, led by Sylvie Vauclair from the University of Toulouse, France, therefore decided to use the technique of 'asteroseismology' to unlock the star's secrets. "In the same way as geologists monitor how seismic waves generated by earthquakes propagate through the Earth and learn about the inner structure of our planet, it is possible to study sound waves running through a star, which forms a sort of large, spherical bell," says Vauclair. The 'ringing' from this giant musical instrument provides astronomers with plenty of information about the physical conditions in the star's interior. And to 'listen to the music', the astronomers used one of the best instruments available. The observations were conducted in November 2006 during 8 consecutive nights with the state-of-the-art HARPS spectrograph mounted on the ESO 3.6-m telescope at La Silla. Up to 25 'notes' could be identified in the unique dataset, most of them corresponding to waves having a period of about 6.5 minutes. These observations allowed the astronomers to obtain a very precise portrait of Iota Horologii: its

  15. The physics of stars

    CERN Document Server

    Phillips, A C

    1999-01-01

    The Physics of Stars, Second Edition, is a concise introduction to the properties of stellar interiors and consequently the structure and evolution of stars. Strongly emphasising the basic physics, simple and uncomplicated theoretical models are used to illustrate clearly the connections between fundamental physics and stellar properties. This text does not intend to be encyclopaedic, rather it tends to focus on the most interesting and important aspects of stellar structure, evolution and nucleosynthesis. In the Second Edition, a new chapter on Helioseismology has been added, along with a list

  16. Atmospheres of central stars

    International Nuclear Information System (INIS)

    Hummer, D.G.

    1978-01-01

    The author presents a brief summary of atmospheric models that are of possible relevance to the central stars of planetary nebulae, and then discusses the extent to which these models accord with the observations of both nebulae and central stars. Particular attention is given to the significance of the very high Zanstra temperature implied by the nebulae He II lambda 4686 A line, and to the discrepancy between the Zanstra He II temperature and the considerably lower temperatures suggested by the appearance of the visual spectrum for some of these objects. (Auth.)

  17. Opposite effects of cell differentiation and apoptosis on Ap3A/Ap4A ratio in human cell cultures.

    Science.gov (United States)

    Vartanian, A; Prudovsky, I; Suzuki, H; Dal Pra, I; Kisselev, L

    1997-09-29

    The biological role of diadenosine oligophosphates (DAOP) remains obscure in spite of numerous attempts to solve this enigma. It is known that Ap3A contrary to Ap4A accumulates in human cultured cells treated with interferons (IFNs) alpha or gamma. Since IFNs are considered as antiproliferative regulators, we assumed that different cell status may be associated with varying intracellular levels of DAOP. Promyelocytic human cell line HL60 induced by phorbol ester (TPA) to differentiate to macrophage-like cells in culture exhibits a profound loss of proliferative potential. Here we have shown a 4-5-fold increase in Ap3A concentration in HL60 cells induced by TPA, similar to the effect of IFN, while the Ap4A concentration remained unchanged. On the contrary, in cells undergoing apoptosis induced by VP16, a topoisomerase II inhibitor, the Ap3A concentration considerably decreased, while the Ap4A concentration increased. These findings combined with earlier results suggest an involvement of the Ap3A/Ap4A ratio in signal transduction pathways controlling the cell status.

  18. [Ce(AP)Λ6 IΛ3-]Dy(AP)Λ6 IΛ3-DMF system at 0 deg C

    International Nuclear Information System (INIS)

    Rukk, N.S.; Kuznetsova, G.P.; Stepin, B.D.

    1985-01-01

    Using isothermal method at 0 deg C, phase equilibria in the system [Ce(AP) 6 ]I 3 -[Dy(AP) 6 ]I 3 -DMF have been studied. It is established, that in the system solid solutions with continuity break are formed, and distribution diagram is referred to type 5 of the Roozeboom classification

  19. Probing neutron star physics using accreting neutron stars

    NARCIS (Netherlands)

    Patruno, A.

    2010-01-01

    We give an obervational overview of the accreting neutron stars systems as probes of neutron star physics. In particular we focus on the results obtained from the periodic timing of accreting millisecond X-ray pulsars in outburst and from the measurement of X-ray spectra of accreting neutron stars

  20. 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.

  1. AP1000R licensing and deployment in the United States

    International Nuclear Information System (INIS)

    Jordan, R. P.; Russ, P. A.; Filiak, P. P.; Castiglione, L. L.

    2012-01-01

    In recent years, both domestic and foreign utilities have turned to the standardized Westinghouse AP1000 plant design in satisfying their near - and long-term - sustainable energy needs. As direct support to these actions, licensing the AP1000 design has played a significant role by providing one of the fundamental bases in clearing regulatory hurdles leading to the start of new plant construction. Within the U.S. alone, Westinghouse AP1000 licensing activities have reached unprecedented milestones with the approvals of both AP1000 Design Certification and Southern Company's combined construction permit and operating license (COL) application directly supporting the construction of two new nuclear plants in Georgia. Further COL application approvals are immediately pending for an additional two AP1000 plants in South Carolina. And, across the U.S. nuclear industry spectrum, there are 10 other COL applications under regulatory review representing some 16 new plants at 10 sites. In total, these actions represent the first wave of new plant licensing under the regulatory approval process since 1978. Fundamental to the Nuclear Regulatory Commission's AP1000 Design Certification is the formal recognition of the AP1000 passive safety design through regulatory acceptance rulemaking. Through recognition and deployment of the AP1000 Design Certification, the utility licensee / operator of this reactor design are now offered an opportunity to use a simplified 'one-step' combined license process, thereby managing substantial back-end construction schedule risk from regulatory and intervention delays. Application of this regulatory philosophy represents both acceptance and encouragement of standardized reactor designs like the AP1000. With the recent AP1000 Design Certification and utility COL acceptances, the fundamental licensing processes of this philosophy have successfully proven the attainment of significant milestones with the next stage licensing actions directed

  2. Forming Stars Near Our Supermassive Black Hole

    Science.gov (United States)

    Kohler, Susanna

    2018-01-01

    of the galactic center made with the Atacama Large Millimeter-Submillimeter Array (ALMA). And this time, they consider what they found to be conclusive.ALMA observations of BP1, one of 11 bipolar outflows signatures of star formation discovered within the central few light-years of our galaxy. BP1 is shown in context at left and zoomed in at right; click for a closer look.[Yusef-Zadeh et al. 2017]Unambiguous SignaturesThe authors deep ALMA observations of the galactic center revealed the presence of 11 bipolar outflows within a few light-years of Sgr A*. These outflows appear as approaching and receding lobes of dense gas that were likely swept up by the jets created as stars were formed within the last 10,000 years. Yusef-Zadeh and collaborators argue that the bipolar outflows are unambiguous signatures of young protostars.Based on these sources, the authors calculate an approximate rate of star formation of 5 x 10-4 solar masses per year in this region. This is large enough that such low-mass star formation over the past few billion years could be a significant contributor to the stellar mass budget in the galactic center.Locations and orientations of the 11 bipolar outflows found. [Yusef-Zadeh et al. 2017]The question of how these stars were able to form so near the black hole remains open. Yusef-Zadeh and collaborators suggest the possibility of events that compress the host cloud, creating star-forming condensations with enough self-gravity to resist tidal disruption by Sgr A*s strong gravitational forces.To verify this picture, the next step is to build a detailed census of low-mass star formation at the galactic center. Were looking forward to seeing how this field has progressed by the next time we report on it!CitationF. Yusef-Zadeh et al 2017 ApJL 850 L30. doi:10.3847/2041-8213/aa96a2

  3. [Star anise poisoning in infants].

    Science.gov (United States)

    Minodier, P; Pommier, P; Moulène, E; Retornaz, K; Prost, N; Deharo, L

    2003-07-01

    Star anise is used as herbal tea, for the treatment of colicky pain in infants. It may cause neurological troubles. We report 2 cases of star anise poisoning in infants before 6 months of age. Star anise herbal tea was given by parents. Tremors or spasms, hypertonia, hyperexcitability with crying, nystagmus, and vomiting were observed. Contamination or adulteration of Chinese star anise (Illicium verum Hook), with Japanese star anise (Illicium religiosum) was proved in one child. Confusion or blending between Chinese and Japanese star anise may cause poisoning. Japanese star anise is a neurotoxic plant indeed, because it contains sesquiterpenic lactones. From November 2001, star anise products are theoretically prohibited in France, but they may be still available in some small groceries, or imported by families themselves.

  4. Kepler observations of Am stars

    DEFF Research Database (Denmark)

    Balona, L. A.; Ripepi, V.; Cantanzaro, G.

    2011-01-01

    We present an analysis of high-resolution spectra for two pulsating Am stars in the Kepler field. The stellar parameters derived in this way are important because parameters derived from narrow-band photometry may be affected by the strong metal lines in these stars. We analyse the Kepler time...... series of ten known Am stars and find that six of them clearly show δ Scuti pulsations. The other four appear to be non-pulsating. We derive fundamental parameters for all known pulsating Am stars from ground-based observations and also for the Kepler Am stars to investigate the location...... of the instability strip for pulsating Am stars. We find that there is not much difference between the Am-star instability strip and the δ Scuti instability strip. We find that the observed location of pulsating Am stars in the HR diagram does not agree with the location predicted from diffusion calculations. Based...

  5. ENERGY STAR Certified Imaging Equipment

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 2.0 ENERGY STAR Program Requirements for Imaging Equipment that are effective as of...

  6. Photometry of faint blue stars

    International Nuclear Information System (INIS)

    Kilkenny, D.; Hill, P.W.; Brown, A.

    1977-01-01

    Photometry on the uvby system is given for 61 faint blue stars. The stars are classified by means of the Stromgren indices, using criteria described in a previous paper (Kilkenny and Hill (1975)). (author)

  7. ENERGY STAR Certified Commercial Boilers

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 1.0 ENERGY STAR Program Requirements for Commercial Boilers that are effective as of...

  8. ENERGY STAR Certified Ceiling Fans

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 3.1 ENERGY STAR Program Requirements for Ceiling Fans that are effective as of April 1,...

  9. ENERGY STAR Certified Ventilating Fans

    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 Ventilating Fans that are effective as of...

  10. ENERGY STAR Certified Water Heaters

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 3.2 ENERGY STAR Program Requirements for Water Heaters that are effective April 16, 2015....

  11. ENERGY STAR Certified Pool Pumps

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 1.1 ENERGY STAR Program Requirements for Pool Pumps that are effective as of February 15,...

  12. ENERGY STAR Certified Roof Products

    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 Roof Products that are effective as of July 1,...

  13. ENERGY STAR Certified Vending Machines

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 3.1 ENERGY STAR Program Requirements for Refrigerated Beverage Vending Machines that are...

  14. UX Ori-Type Stars

    Science.gov (United States)

    Grinin, V.

    2017-06-01

    The brief review of the properties of the UX Ori type stars is presented. A special attention is given to the results of the Crimean program of the multi-year photometric and polarimetric observations of these stars.

  15. ENERGY STAR Certified Commercial Dishwashers

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 2.0 ENERGY STAR Program Requirements for Commercial Dishwashers that are effective as of...

  16. ENERGY STAR Certified Enterprise Servers

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 2.1 ENERGY STAR Program Requirements for Enterprise Servers that are effective as of...

  17. ENERGY STAR Certified Commercial Griddles

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 1.2 ENERGY STAR Program Requirements for Commercial Griddles that are effective as of May...

  18. ENERGY STAR Certified Audio Video

    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 Audio Video Equipment that are effective as of...

  19. Eruptive star V1180 Cas now in outburst

    Science.gov (United States)

    Antoniucci, S.; Arkharov, A. A.; Efimova, N.; Kopatskaya, E. N.; Larionov, V. M.; Di Paola, A.; Giannini, T.; Li Causi, G.; Lorenzetti, D.; Vitali, F.

    2013-09-01

    In the framework of our optical/near-IR EXor monitoring program dubbed EXORCISM (EXOR optiCal Infrared Systematic Monitoring - Antoniucci et al. PPVI), we have been observing since two months the variable star V1180 Cas, associated with the dark cloud Lynds 1340. This source has been originally recognized as a young eruptive object by Kun et al. (2011, ApJ 733, L8), who observed a powerful outburst (5-6 mag in the Ic band) in the period 2005-2008.

  20. 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

  1. Forming Stars From the Cosmic Web

    Science.gov (United States)

    Kohler, Susanna

    2015-09-01

    ) in metallicity along a portion of their lengths. The metallicity drops corresponded to bright knots representing starburst regions, in which surface star formation rates are larger than that of the rest of the galaxy by factors of 10100.The authors conclude that in these galaxies, a cold cosmic gas cloud with low metallicity impacted the galaxys outer region. This impact caused the cloud to compress, triggering the star formation we now observe. At the same time, the gas from the cloud diluted the regions metallicity, resulting in the low abundances now measured. The authors determine that the cloud impacted within the last 100 Myr otherwise enough time would have passed for the gas to mix azimuthally as it rotated around the galaxy.CitationJ. Snchez Almeida et al 2015 ApJ 810 L15. doi:10.1088/2041-8205/810/2/L15

  2. Raising the acceptance of the AP2-line

    International Nuclear Information System (INIS)

    Trbojevic, D.

    1989-01-01

    The 120 GeV Main Ring proton beam collides with the target at the end of the AP-1 line and creates antiprotons and other secondary particles. The AP-2 line transfers the negative particles from the target to the Debuncher. To provide a bigger antiproton stack size in the Accumulator, both the Debuncher as well as the AP-2 line acceptance have to be raised. This is a proposal for the improvement of the AP-2 line acceptance. The first part of the memo presents an acceptance examination of the existing AP-2 line by computer simulation, while the second presents a short proposal for aperture corrections. The computer program TURTLE was used to trace antiprotons through the AP-2 line without taking into account other negative charged particles. Betatron functions were obtained from the output of the SYNCH computer program. The SYNCH program was also used to check the dispersion match between the AP-2 line and the Debuncher. 3 refs., 6 figs., 5 tabs

  3. Comparing P-stars with Observations

    OpenAIRE

    Cea, Paolo

    2007-01-01

    P-stars are compact stars made of up and down quarks in $\\beta$-equilibrium with electrons in a chromomagnetic condensate. P-stars are able to account for compact stars as well as stars with radius comparable with canonical neutron stars. We compare p-stars with different available observations. Our results indicate that p-stars are able to reproduce in a natural manner several observations from isolated and binary pulsars.

  4. Dicty_cDB: FC-AP12 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available FC (Link to library) FC-AP12 (Link to dictyBase) - G01739 DDB0232214 Contig-U15924-1 FC-AP...12P (Link to Original site) FC-AP12F 323 FC-AP12Z 613 FC-AP12P 936 - - Show FC-AP12 Library FC (Link ...ontig Contig-U15924-1 Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/FC/FC-AP/FC-AP...12Q.Seq.d/ Representative seq. ID FC-AP12P (Link to Original site) Representative DNA sequence >FC-AP12 (FC-AP...12Q) /CSM/FC/FC-AP/FC-AP12Q.Seq.d/ CATATTATTTTAAATTTCAGATGTTCCCAAAATAACACATTAATTTGCTTTTTTTGTTG

  5. Dicty_cDB: FC-AP23 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available FC (Link to library) FC-AP23 (Link to dictyBase) - G03230 DDB0190153 Contig-U16094-1 FC-AP...23P (Link to Original site) FC-AP23F 515 FC-AP23Z 472 FC-AP23P 987 - - Show FC-AP23 Library FC (Link ...ontig Contig-U16094-1 Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/FC/FC-AP/FC-AP...23Q.Seq.d/ Representative seq. ID FC-AP23P (Link to Original site) Representative DNA sequence >FC-AP23 (FC-AP...23Q) /CSM/FC/FC-AP/FC-AP23Q.Seq.d/ CAAATACATAATCTCTTTTTTGAAAATGTCCGAAAATAACGAAATTGAAATGGAACTCC

  6. Dicty_cDB: FC-AP05 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available FC (Link to library) FC-AP05 (Link to dictyBase) - - - Contig-U16521-1 FC-AP05Z (Li...nk to Original site) - - FC-AP05Z 532 - - - - Show FC-AP05 Library FC (Link to library) Clone ID FC-AP05 (Li.../dictycdb.biol.tsukuba.ac.jp/CSM/FC/FC-AP/FC-AP05Q.Seq.d/ Representative seq. ID FC-AP...05Z (Link to Original site) Representative DNA sequence >FC-AP05 (FC-AP05Q) /CSM/FC/FC-AP/FC-AP05Q.Seq....GAGA TCCGTCAAAGTTTCAAGCAAAAAAGTTGTTGCCAAGTAAATAAATAATACTTTTTTCCCT AT sequence update 1997. 3.25 Translated Amino Acid sequence ---AP

  7. Asteroseismology of Scuti Stars

    Indian Academy of Sciences (India)

    Abstract. We briefly outline the state-of-the-art seismology of Scuti stars from a theoretical point of view: why is it so difficult a task? The recent theoretical advances in the field that these difficulties have influenced are also discussed.

  8. Hadrons in compact stars

    Indian Academy of Sciences (India)

    physics pp. 817–825. Hadrons in compact stars. DEBADES BANDYOPADHYAY. Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700 064, India ... There is a growing interplay between the physics of dense matter in relativistic .... Kaplan and Nelson [7] first showed in a chiral SU(3)L × SU(3)R model that.

  9. Millet's Shooting Stars

    Science.gov (United States)

    Beech, M.

    1988-12-01

    In this essay two paintings by the French artist Jean-Francois Millet are described. These paintings, Les Etoiles Filantes and Nuit Etoilée are particularly interesting since they demonstrate the rare artistic employment of the shooting-star image and metaphor.

  10. Reaching for the Stars

    Science.gov (United States)

    Terry, Dorothy Givens

    2012-01-01

    Dr. Mae Jemison is the world's first woman astronaut of color who continues to reach for the stars. Jemison was recently successful in leading a team that has secured a $500,000 federal grant to make interstellar space travel a reality. The Dorothy Jemison Foundation for Excellence (named after Jemison's mother) was selected in June by the Defense…

  11. Interacting binary stars

    International Nuclear Information System (INIS)

    Pringle, J.E.; Wade, R.A.

    1985-01-01

    This book reviews the theoretical and observational knowledge of interacting binary stars. The topics discussed embrace the following features of these objects: their orbits, evolution, mass transfer, angular momentum losses, X-ray emission, eclipses, variability, and other related phenomena. (U.K.)

  12. THE STAR OFFLINE FRAMEWORK

    International Nuclear Information System (INIS)

    FINE, V.; FISYAK, Y.; PEREVOZTCHIKOV, V.; WENAUS, T.

    2000-01-01

    The Solenoidal Tracker At RHIC (STAR) is a-large acceptance collider detector, commissioned at Brookhaven National Laboratory in 1999. STAR has developed a software framework supporting simulation, reconstruction and analysis in offline production, interactive physics analysis and online monitoring environments that is well matched both to STAR's present status of transition between Fortran and C++ based software and to STAR's evolution to a fully OO software base. This paper presents the results of two years effort developing a modular C++ framework based on the ROOT package that encompasses both wrapped Fortran components (legacy simulation and reconstruction code) served by IDL-defined data structures, and fully OO components (all physics analysis code) served by a recently developed object model for event data. The framework supports chained components, which can themselves be composite subchains, with components (''makers'') managing ''data sets'' they have created and are responsible for. An St-DataSet class from which data sets and makers inherit allows the construction of hierarchical organizations of components and data, and centralizes almost all system tasks such as data set navigation, I/O, database access, and inter-component communication. This paper will present an overview of this system, now deployed and well exercised in production environments with real and simulated data, and in an active physics analysis development program

  13. Hadrons in compact stars

    Indian Academy of Sciences (India)

    At normal nuclear matter density, neutron star matter mainly consists of neutrons, protons and electrons. The particle population is so arranged as to attain a min- imum energy configuration maintaining electrical charge neutrality and chemical equilibrium. At higher baryon density, hyperon formation becomes energetically.

  14. Alignement experience in STAR

    CERN Document Server

    Margetis, S; Lauret, J; Perevozchikov, V; Van Buren, G; Bouchef, J

    2007-01-01

    The STAR experiment at RHIC uses four layers of silicon strip and silicon drift detectors for secondary vertex reconstruction. An attempt for a direct charm meson measurement put stringent requirements on alignment and calibration. We report on recent alignment and drift velocity calibration work performed on the inner silicon tracking system.

  15. Seismology of active stars

    NARCIS (Netherlands)

    Hekker, S.; García, R.A.

    2012-01-01

    In this review we will discuss the current standing and open questions of seismology in active stars. With the longer photometric time series data that are, and will become, available from space-missions such as Kepler we foresee significant progress in our understanding of stellar internal

  16. Triggered star formation

    Czech Academy of Sciences Publication Activity Database

    Palouš, Jan; Ehlerová, Soňa

    2002-01-01

    Roč. 12, - (2002), s. 35-36 ISSN 1405-2059 R&D Projects: GA AV ČR IAA3003705; GA AV ČR KSK1048102 Institutional research plan: CEZ:AV0Z1003909 Keywords : interstellar medium * star formation * HI shells Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  17. I see falling stars

    CERN Document Server

    Orr, Tamra B

    2015-01-01

    "Young children are naturally curious about the world around them. I See Falling Stars offers answers to their most compelling questions about meteors. Age-appropriate explanations and appealing photos encourage readers to continue their quest for knowledge. Additional text features and search tools, including a glossary and an index, help students locate information and learn new words."-- Provided by publisher.

  18. Astrometric microlensing of stars

    NARCIS (Netherlands)

    Dominik, M; Sahu, KC

    2000-01-01

    Because of dramatic improvements in the precision of astrometric measurements, the observation of light centroid shifts in observed stars due to intervening massive compact objects ("astrometric microlensing") will become possible in the near future. Upcoming space missions, such as SIM and GAIA,

  19. Gas Between the Stars

    Indian Academy of Sciences (India)

    backstage. Keywords. Thermal equilibrium, interstellar gas, galaxies. The discovery of the interstellar gas itself was serendipitous. In. RESONANCE | November 2016. 985 ... ment, the electron is usually knocked down from the aligned case ..... it was asserted that explosions that some stars end their nuclear burning phase ...

  20. High p physics at STAR

    Indian Academy of Sciences (India)

    sub sub

    physics pp. 933–944. High p. T physics at STAR. SUBHASIS CHATTOPADHYAY, for the STAR Collaboration. Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700 064, India. Abstract. We discuss the capabilities of STAR in exploring the physics at high pT in ultrarelativis- tic heavy-ion colisions from RHIC at.

  1. Carbon Stars T. Lloyd Evans

    Indian Academy of Sciences (India)

    Introduction. Carbon stars have been reviewed on several previous occasions, most recently by. Wallerstein & Knapp (1998). A conference devoted to this topic was held in 1996. (Wing 2000) and two meetings on AGB stars (Le Bertre et al. 1999; Kerschbaum et al. 2007) also contain much on carbon stars. This review ...

  2. 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.

  3. Protecting the lower extremity against a/p blast mines

    CSIR Research Space (South Africa)

    van Dyk, T

    2006-09-01

    Full Text Available protection concept Result: Chaos and arguments Slide 4 © CSIR 2006 www.csir.co.za A/P Blast Mines Effects Slide 5 © CSIR 2006 www.csir.co.za Basic Principles Shock Effect Slide 6 © CSIR 2006... the Lower Extremity against a/p Blast Mines J T van Dyk DEFENCE, PEACE, SAFETY AND SECURITY LANDWARDS SCIENCES COMPETENCY AREA Slide 2 © CSIR 2006 www.csir.co.za Contents • R&D overview • Effect of a/p blast mines • Basic...

  4. MULTI-OBJECTIVE ONLINE OPTIMIZATION OF BEAM LIFETIME AT APS

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yipeng

    2017-06-25

    In this paper, online optimization of beam lifetime at the APS (Advanced Photon Source) storage ring is presented. A general genetic algorithm (GA) is developed and employed for some online optimizations in the APS storage ring. Sextupole magnets in 40 sectors of the APS storage ring are employed as variables for the online nonlinear beam dynamics optimization. The algorithm employs several optimization objectives and is designed to run with topup mode or beam current decay mode. Up to 50\\% improvement of beam lifetime is demonstrated, without affecting the transverse beam sizes and other relevant parameters. In some cases, the top-up injection efficiency is also improved.

  5. Capturing Neutrinos from a Star's Final Hours

    Science.gov (United States)

    Hensley, Kerry

    2018-04-01

    Patton (University of Washington) and collaborators first used a stellar evolution model to explore neutrino production in massive stars. They modeled the evolution of two massive stars 15 and 30 times the mass of our Sun from the onset of nuclear fusion to the moment of collapse.The authors found that in the last few hours before collapse, during which the material in the stars cores is rapidly upcycled into heavier elements, the flux from beta-process neutrinos rivals that of thermal neutrinos and even exceeds it at high energies. So now we know there are many beta-process neutrinos but can we spot them?Neutrino and antineutrino fluxes at Earth from the last 2 hours of a 30-solar-mass stars life compared to the flux from background sources. The rows represent calculations using two different neutrino mass hierarchies. Click to enlarge. [Patton et al. 2017]Observing Elusive NeutrinosFor an imminent supernova at a distance of 1 kiloparsec, the authors find that the presupernova electron neutrino flux rises above the background noise from the Sun, nuclear reactors, and radioactive decay within the Earth in the final two hours before collapse.Based on these calculations, current and future neutrino observatories should be able to detect tens of neutrinos from a supernova within 1 kiloparsec, about 30% of which would be beta-process neutrinos. As the distance to the star increases, the time and energy window within which neutrinos can be observed gradually narrows, until it closes for stars at a distance of about 30 kiloparsecs.Are there any nearby supergiants soon to go supernova so these predictions can be tested? At a distance of only 650 light-years, the red supergiant star Betelgeuse should produce detectable neutrinos when it explodes an exciting opportunity for astronomers in the far future!CitationKelly M. Patton et al 2017ApJ8516. doi:10.3847/1538-4357/aa95c4

  6. Human Immunodeficiency Virus Type 2 (HIV-2) Gag Is Trafficked in an AP-3 and AP-5 Dependent Manner.

    Science.gov (United States)

    Alford, Justine E; Marongiu, Michela; Watkins, Gemma L; Anderson, Emma C

    2016-01-01

    Although human immunodeficiency virus (HIV) types 1 and 2 are closely related lentiviruses with similar replication cycles, HIV-2 infection is associated with slower progression to AIDS, a higher proportion of long term non-progressors, and lower rates of transmission than HIV-1, likely as a consequence of a lower viral load during HIV-2 infection. A mechanistic explanation for the differential viral load remains unclear but knowledge of differences in particle production between HIV-1 and HIV-2 may help to shed light on this issue. In contrast to HIV-1, little is known about the assembly of HIV-2 particles, and the trafficking of HIV-2 Gag, the structural component of the virus, within cells. We have established that HIV-2 Gag accumulates in intracellular CD63 positive compartments, from which it may be delivered or recycled to the cell surface, or degraded. HIV-2 particle release was dependent on the adaptor protein complex AP-3 and the newly identified AP-5 complex, but much less so on AP-1. In contrast, HIV-1 particle release required AP-1 and AP-3, but not AP-5. AP-2, an essential component of clathrin-mediated endocytosis, which was previously shown to be inhibitory to HIV-1 particle release, had no effect on HIV-2. The differential requirement for adaptor protein complexes confirmed that HIV-1 and HIV-2 Gag have distinct cellular trafficking pathways, and that HIV-2 particles may be more susceptible to degradation prior to release.

  7. A Vanishing Star Revisited

    Science.gov (United States)

    1999-07-01

    VLT Observations of an Unusual Stellar System Reinhold Häfner of the Munich University Observatory (Germany) is a happy astronomer. In 1988, when he was working at a telescope at the ESO La Silla observatory, he came across a strange star that suddenly vanished off the computer screen. He had to wait for more than a decade to get the full explanation of this unusual event. On June 10-11, 1999, he observed the same star with the first VLT 8.2-m Unit Telescope (ANTU) and the FORS1 astronomical instrument at Paranal [1]. With the vast power of this new research facility, he was now able to determine the physical properties of a very strange stellar system in which two planet-size stars orbit each other. One is an exceedingly hot white dwarf star , weighing half as much as the Sun, but only twice as big as the Earth. The other is a much cooler and less massive red dwarf star , one-and-a-half times the size of planet Jupiter. Once every three hours, the hot star disappears behind the other, as seen from the Earth. For a few minutes, the brightness of the system drops by a factor of more than 250 and it "vanishes" from view in telescopes smaller than the VLT. A variable star named NN Serpentis ESO PR Photo 30a/99 ESO PR Photo 30a/99 [Preview - JPEG: 400 x 468 pix - 152k] [Normal - JPEG: 800 x 936 pix - 576k] [High-Res - JPEG: 2304 x 2695 pix - 4.4M] Caption to ESO PR Photo 30a/99 : The sky field around the 17-mag variable stellar system NN Serpentis , as seen in a 5 sec exposure through a V(isual) filter with VLT ANTU and FORS1. It was obtained just before the observation of an eclipse of this unsual object and served to centre the telescope on the corresponding sky position. The field shown here measures 4.5 x 4.5 armin 2 (1365 x 1365 pix 2 ; 0.20 arcsec/pix). The field is somewhat larger than that shown in Photo 30b/99 and has the same orientation to allow comparison: North is about 20° anticlockwise from the top and East is 90° clockwise from that direction. The

  8. Star identification methods, techniques and algorithms

    CERN Document Server

    Zhang, Guangjun

    2017-01-01

    This book summarizes the research advances in star identification that the author’s team has made over the past 10 years, systematically introducing the principles of star identification, general methods, key techniques and practicable algorithms. It also offers examples of hardware implementation and performance evaluation for the star identification algorithms. Star identification is the key step for celestial navigation and greatly improves the performance of star sensors, and as such the book include the fundamentals of star sensors and celestial navigation, the processing of the star catalog and star images, star identification using modified triangle algorithms, star identification using star patterns and using neural networks, rapid star tracking using star matching between adjacent frames, as well as implementation hardware and using performance tests for star identification. It is not only valuable as a reference book for star sensor designers and researchers working in pattern recognition and othe...

  9. Neutron stars and quark stars: Two coexisting families of compact stars?

    OpenAIRE

    Schaffner-Bielich, J.

    2006-01-01

    The mass-radius relation of compact stars is discussed with relation to the presence of quark matter in the core. The existence of a new family of compact stars with quark matter besides white dwarfs and ordinary neutron stars is outlined.

  10. Smashing a Jet into a Cloud to Form Stars

    Science.gov (United States)

    Kohler, Susanna

    2017-12-01

    computational astrophysics code called Cosmos++ to produce three-dimensional hydrodynamic simulations of an AGN jet colliding with a spherical intergalactic cloud. They show that the collision triggers a series shocks that move through and around the cloud, condensing the gas and triggering runaway cooling instabilities that can lead to cloud clumps collapsing to form stars.The authors are able to find a model in which the dramatic increase in the star formation rate matches that measured for Minkowskis Object very well. In particular, the increased star formation occurs upstream of the bulk of the available H I gas, which is consistent with observations of Minkowskis Object and implicates the jets interaction with the cloud as the cause.The spatial distribution of particles tracing stars that formed as a result of the jet entering from the left, after 40 million years. Color tracks the particle age (in Myr) in the top panel and particle velocity (in km/s) inthe bottom. [Adapted from Fragile et al. 2017]An intriguing result of the authors simulations is a look at the spatial distribution of the velocities of stars that form when triggered by the jet. Because the propagation speed of the star-formation front gradually slows, the fastest-moving stars are those that were formed first, and they are found furthest downstream. This provides an interesting testable prediction we can look to see if a similar distribution is visible in Minkowskis Object.Fragile and collaborators plan further refinements to their simulations, but they argue that the success of their model to reproduce observations of Minkowskis Object are very promising. Positive feedback from AGN jets indeed appears to have an important impact on the surrounding environment.CitationP. Chris Fragile et al 2017 ApJ 850 171. doi:10.3847/1538-4357/aa95c6

  11. 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.

  12. A hot-spare injector for the APS linac

    International Nuclear Information System (INIS)

    Lewellen, J. W.

    1999-01-01

    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

  13. Ecology of blue straggler stars

    CERN Document Server

    Carraro, Giovanni; Beccari, Giacomo

    2015-01-01

    The existence of blue straggler stars, which appear younger, hotter, and more massive than their siblings, is at odds with a simple picture of stellar evolution. Such stars should have exhausted their nuclear fuel and evolved long ago to become cooling white dwarfs. They are found to exist in globular clusters, open clusters, dwarf spheroidal galaxies of the Local Group, OB associations and as field stars. This book summarises the many advances in observational and theoretical work dedicated to blue straggler stars. Carefully edited extended contributions by well-known experts in the field cover all the relevant aspects of blue straggler stars research: Observations of blue straggler stars in their various environments; Binary stars and formation channels; Dynamics of globular clusters; Interpretation of observational data and comparison with models. The book also offers an introductory chapter on stellar evolution written by the editors of the book.

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

    Directory of Open Access Journals (Sweden)

    Emmanuel Boucrot

    2010-05-01

    Full Text Available 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.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.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 conditions of stress, cells can upregulate alternative endocytic structures

  15. Differential recognition of a dileucine-based sorting signal by AP-1 and AP-3 reveals a requirement for both BLOC-1 and AP-3 in delivery of OCA2 to melanosomes

    Science.gov (United States)

    Sitaram, Anand; Dennis, Megan K.; Chaudhuri, Rittik; De Jesus-Rojas, Wilfredo; Tenza, Danièle; Setty, Subba Rao Gangi; Wood, Christopher S.; Sviderskaya, Elena V.; Bennett, Dorothy C.; Raposo, Graça; Bonifacino, Juan S.; Marks, Michael S.

    2012-01-01

    Cell types that generate unique lysosome-related organelles (LROs), such as melanosomes in melanocytes, populate nascent LROs with cargoes that are diverted from endosomes. Cargo sorting toward melanosomes correlates with binding via cytoplasmically exposed sorting signals to either heterotetrameric adaptor AP-1 or AP-3. Some cargoes bind both adaptors, but the relative contribution of each adaptor to cargo recognition and their functional interactions with other effectors during transport to melanosomes are not clear. Here we exploit targeted mutagenesis of the acidic dileucine–based sorting signal in the pigment cell–specific protein OCA2 to dissect the relative roles of AP-1 and AP-3 in transport to melanosomes. We show that binding to AP-1 or AP-3 depends on the primary sequence of the signal and not its position within the cytoplasmic domain. Mutants that preferentially bound either AP-1 or AP-3 each trafficked toward melanosomes and functionally complemented OCA2 deficiency, but AP-3 binding was necessary for steady-state melanosome localization. Unlike tyrosinase, which also engages AP-3 for optimal melanosomal delivery, both AP-1– and AP-3–favoring OCA2 variants required BLOC-1 for melanosomal transport. These data provide evidence for distinct roles of AP-1 and AP-3 in OCA2 transport to melanosomes and indicate that BLOC-1 can cooperate with either adaptor during cargo sorting to LROs. PMID:22718909

  16. Analysis and characterization of double shell tank 241-AP-108

    International Nuclear Information System (INIS)

    Miller, G.L.

    1994-01-01

    This document is the first part of a three-part report describing the analysis and characterization of double shell tank 241-AP-108 which is located at the Hanford Reservation.This document is the analytical laboratory data package entitled 'Analysis and Characterization of Double Shell Tank 241-AP-108' which contains a case sampling history, the sampling protocols, the analytical procedures, sampling and analysis quality assurance and quality control measures, and chemical analysis results for samples obtained from the tank

  17. Approaching acquisition path analysis formally. A comparison between AP and nonAP states

    International Nuclear Information System (INIS)

    Listner, Clemens; Canty, Morton J.; Niemeyer, Irmgard; Rezniczek, Arnold; Stein, Gotthard

    2014-01-01

    In the past, the IAEA has planned its activities mainly based on the presence of nuclear material. However, resources should be spent where they are needed most. Therefore, a new risk model was developed to change the inspection system to a comprehensive, objective‑driven approach where the State is considered as a whole, the so called State‑level concept (SLC). Acquisition path analysis (APA) is a key element of the State‑level concept. By considering the State’s nuclear profile, the APA generates a list of acquisition paths ranked by their attractiveness for the State. Currently, this process is mainly based on expert judgment. However, the IAEA’s requirements state that APA must be objective, reproducible, transparent, standardized, documented and as a result non‑discriminatory. A formal approach fulfilling the requirements was set up by the authors in the past [1]. This methodology is based on a three step approach. The process starts in the first step with the parametrization of the network. In the second step, the network is analyzed in order find all acquisition paths for a State. Finally, game theory is used in the third step to model the decisions made by the IAEA and the State. In this paper, an advanced methodology will be presented. Improvements were made in the interface definition between the three stages. Also, the general network model was updated and the automatic visualization of acquisition paths was accomplished. Furthermore, a prototype implementation will be shown. The advanced methodology was applied to two test non‑nuclear weapon States under comprehensive safeguards agreements with the IAEA. Both States hold complex fuel cycles with only small technical differences. However,only one State is supposed to have the additional protocol (AP) in force. The example will show how the presence of the AP influences the detection probabilities of illegal behavior. As a consequence, these examples also indicate where to best focus

  18. Tracing the Fuel for Forming Stars

    Science.gov (United States)

    Kohler, Susanna

    2017-11-01

    galaxies at this distance, it would suggest that gas reservoirs have drastically changed in the short time between then and now.But a team of scientists from the International Centre for Radio Astronomy Research in Australia, led by Luca Cortese, has now challenged this conclusion.Top: molecular vs. atomic hydrogen gas in galaxies between z = 0 and z = 1.5. Bottom: the evolution of the molecular-to-atomic mass ratio with redshift. [Adapted from Cortese et al. 2017]Adding to the SampleCortese and collaborators combined observations from the Atacama Large Millimeter/submillimeter Array (ALMA) and Arecibo to estimate the ratio of molecular to atomic hydrogen in five HIGHz-survey massive star-forming galaxies at a redshift of z 0.2. They then combine these results with those of the COOL BUDHIES survey; they argue that, since the two surveys use different selection criteria, the combination of the two samples provides a fairer view of the overall population of star-forming galaxies at z 0.2.Intriguingly, the HIGHz galaxies do not show the molecular-gas dominance that the COOL BUDHIES galaxies do. Cortese and collaborators demonstrate that the addition of the HIGHz galaxies to the sample reveals that the gas reservoirs of star-forming disks 3 billion years ago are, in fact, still the same as what we see today, suggesting that star formation in galaxies at z 0.2 is likely fueled in much the same way as it is today.As telescope capabilities increase, we may be able to explore whether this continues to hold true for more distant galaxies. In the meantime, increasing our sample size within the range that we can observe will help us to further explore how galaxies have formed stars over time.CitationLuca Cortese et al 2017 ApJL 848 L7. doi:10.3847/2041-8213/aa8cc3

  19. Dicty_cDB: FC-AP18 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available FC (Link to library) FC-AP18 (Link to dictyBase) - - - Contig-U16455-1 FC-AP18Z (Li...nk to Original site) - - FC-AP18Z 367 - - - - Show FC-AP18 Library FC (Link to library) Clone ID FC-AP18 (Li.../dictycdb.biol.tsukuba.ac.jp/CSM/FC/FC-AP/FC-AP18Q.Seq.d/ Representative seq. ID FC-AP...18Z (Link to Original site) Representative DNA sequence >FC-AP18 (FC-AP18Q) /CSM/FC/FC-AP/FC-AP18Q.Seq....XELTPSRPMCVESFNEYPP LGRFAVRDMGQTVAVGVIKSTVKKAPGKAGDKKGAXAPSKKK*innis**iafynnfkkk kkkkk Translated Amino Acid

  20. Dicty_cDB: FC-AP16 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available FC (Link to library) FC-AP16 (Link to dictyBase) - - - Contig-U16269-1 FC-AP16Z (Li...nk to Original site) - - FC-AP16Z 552 - - - - Show FC-AP16 Library FC (Link to library) Clone ID FC-AP16 (Li.../dictycdb.biol.tsukuba.ac.jp/CSM/FC/FC-AP/FC-AP16Q.Seq.d/ Representative seq. ID FC-AP...16Z (Link to Original site) Representative DNA sequence >FC-AP16 (FC-AP16Q) /CSM/FC/FC-AP/FC-AP16Q.Seq....7. 3.28 Translated Amino Acid sequence ---RNRRYKVRKGPLVVVSGKTTVSQALRNIPGVEVANVSRLNLLKLAPGGHLGRFIIWT KSAFEQLD

  1. Dicty_cDB: FC-AP15 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available FC (Link to library) FC-AP15 (Link to dictyBase) - - - Contig-U15444-1 FC-AP15Z (Li...nk to Original site) - - FC-AP15Z 594 - - - - Show FC-AP15 Library FC (Link to library) Clone ID FC-AP15 (Li.../dictycdb.biol.tsukuba.ac.jp/CSM/FC/FC-AP/FC-AP15Q.Seq.d/ Representative seq. ID FC-AP...15Z (Link to Original site) Representative DNA sequence >FC-AP15 (FC-AP15Q) /CSM/FC/FC-AP/FC-AP15Q.Seq....AAAAAAAAAAAAAAAAAA AAAA sequence update 1997. 3.25 Translated Amino Acid sequence ---RLLKIAEARAATPKGQAAPKAEK

  2. Dicty_cDB: FC-AP17 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 4.1 SJMBIB09 SJM Schistosoma japonicum cDNA, mRNA sequence. 80 8e-20 2 BE859184 |BE859184.1 SsS0499 Suaeda salsa ZAP...FC (Link to library) FC-AP17 (Link to dictyBase) - - - Contig-U16254-1 FC-AP17Z (Li...nk to Original site) - - FC-AP17Z 546 - - - - Show FC-AP17 Library FC (Link to library) Clone ID FC-AP17 (Li.../dictycdb.biol.tsukuba.ac.jp/CSM/FC/FC-AP/FC-AP17Q.Seq.d/ Representative seq. ID FC-AP...17Z (Link to Original site) Representative DNA sequence >FC-AP17 (FC-AP17Q) /CSM/FC/FC-AP/FC-AP17Q.Seq.

  3. Dicty_cDB: FC-AP11 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available A clone IMAGE:4920557 5', mRNA sequence. 56 1e-04 2 BF345929 |BF345929.1 602017931F1 NCI_CGAP_Brn67 Homo sap...FC (Link to library) FC-AP11 (Link to dictyBase) - - - Contig-U16101-1 FC-AP11F (Li...nk to Original site) FC-AP11F 394 - - - - - - Show FC-AP11 Library FC (Link to library) Clone ID FC-AP11 (Li.../dictycdb.biol.tsukuba.ac.jp/CSM/FC/FC-AP/FC-AP11Q.Seq.d/ Representative seq. ID FC-AP...11F (Link to Original site) Representative DNA sequence >FC-AP11 (FC-AP11Q) /CSM/FC/FC-AP/FC-AP11Q.Seq.

  4. Neutron Star Science with the NuSTAR

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, J. K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-10-16

    The Nuclear Spectroscopic Telescope Array (NuSTAR), launched in June 2012, helped scientists obtain for the first time a sensitive high-­energy X-­ray map of the sky with extraordinary resolution. This pioneering telescope has aided in the understanding of how stars explode and neutron stars are born. LLNL is a founding member of the NuSTAR project, with key personnel on its optics and science team. We used NuSTAR to observe and analyze the observations of different neutron star classes identified in the last decade that are still poorly understood. These studies not only help to comprehend newly discovered astrophysical phenomena and emission processes for members of the neutron star family, but also expand the utility of such observations for addressing broader questions in astrophysics and other physics disciplines. For example, neutron stars provide an excellent laboratory to study exotic and extreme phenomena, such as the equation of state of the densest matter known, the behavior of matter in extreme magnetic fields, and the effects of general relativity. At the same time, knowing their accurate populations has profound implications for understanding the life cycle of massive stars, star collapse, and overall galactic evolution.

  5. The Westinghouse Advanced Passive Pressurized Water Reactor, AP1000

    International Nuclear Information System (INIS)

    Schene, R.

    2009-01-01

    Featuring proven technology and innovative passive safety systems, the Westinghouse AP1000 pressurized water reactor can achieve competitive generation costs in the current electricity market without emitting harmful greenhouse gases and further harming the environment. Westinghouse Electric Company, the pioneer in nuclear energy once again sets a new industry standard with the AP1000. The AP1000 is a two-loop pressurized water reactor that uses simplified, innovative and effective approach to safety. With a gross power rating of 3415 megawatt thermal and a nominal net electrical output of 1117 megawatt electric, the AP1000 is ideal for new base load generation. The AP1000 is the safest and most economical nuclear power plant available in the worldwide commercial marketplace, and is the only Generation III+ reactor to receive a design certification from the U.S. Nuclear Regulatory Commission (NRC). Based on nearly 20 years of research and development, the AP1000 builds and improves upon the established technology of major components used in current Westinghouse designed plants. These components, including steam generators, digital instrumentation and controls, fuel, pressurizers, and reactor vessels, are currently in use around the world and have years of proven, reliable operating experience. Historically, Westinghouse plant designs and technology have forged the cutting edge technology of nuclear plant around the world. Today, nearly 50 percent of the world's 440 nuclear plants are based on Westinghouse technology. Westinghouse continues to be the nuclear industry's global leader. (author)

  6. From stars to planets

    Science.gov (United States)

    Gazzano, Jean-Christophe; Deleuil, Magali; De Laverny, Patrick; Blanco, Alejandra Recio; Bouchy, François; Gandolfi, Davide; Loeillet, Benoît

    2009-02-01

    A large program of multi-fibre (FLAMES) spectroscopic observations of the stellar population in two CoRoT/Exoplanet field with the GIRAFFE/VLT, took place in spring 2008. It aims at characterizing the brightest dwarf population and providing the ground for statistical analysis of the planetary population found by CoRoT. To perform such an ambitious analysis, we use an automated software based on the MATISSE algorithm, originally designed for the GAIA/RVS spectral analysis. This software derives the atmospheric stellar parameters: effective temperature, surface gravity and the overall metallicity. Further improvements are foreseen in order to measure also individual abundances. By comparing the main physical and chemical properties of the host stars to those of the stellar population they belong to, this will bring new insights into the formation and evolution of exoplanetary systems and the star-planet connection.

  7. White Dwarf Stars

    Science.gov (United States)

    1999-01-01

    Peering deep inside a cluster of several hundred thousand stars, NASA's Hubble Space Telescope has uncovered the oldest burned-out stars in our Milky Way Galaxy, giving astronomers a fresh reading on the age of the universe. Located in the globular cluster M4, these small, burned-out stars -- called white dwarfs -- are about 12 to 13 billion years old. By adding the one billion years it took the cluster to form after the Big Bang, astronomers found that the age of the white dwarfs agrees with previous estimates that the universe is 13 to 14 billion years old. The images, including some taken by Hubble's Wide Field and Planetary Camera 2, are available online at http://oposite.stsci.edu/pubinfo/pr/2002/10/ or http://www.jpl.nasa.gov/images/wfpc . The camera was designed and built by NASA's Jet Propulsion Laboratory, Pasadena, Calif. In the top panel, a ground-based observatory snapped a panoramic view of the entire cluster, which contains several hundred thousand stars within a volume of 10 to 30 light-years across. The Kitt Peak National Observatory's .9-meter telescope took this picture in March 1995. The box at left indicates the region observed by the Hubble telescope. The Hubble telescope studied a small region of the cluster. A section of that region is seen in the picture at bottom left. A sampling of an even smaller region is shown at bottom right. This region is only about one light-year across. In this smaller region, Hubble pinpointed a number of faint white dwarfs. The blue circles indicate the dwarfs. It took nearly eight days of exposure time over a 67-day period to find these extremely faint stars. Globular clusters are among the oldest clusters of stars in the universe. The faintest and coolest white dwarfs within globular clusters can yield a globular cluster's age. Earlier Hubble observations showed that the first stars formed less than 1 billion years after the universe's birth in the big bang. So, finding the oldest stars puts astronomers within

  8. Pulsating stars harbouring planets

    Directory of Open Access Journals (Sweden)

    Moya A.

    2013-04-01

    Full Text Available Why bother with asteroseismology while studying exoplanets? There are several answers to this question. Asteroseismology and exoplanetary sciences have much in common and the synergy between the two opens up new aspects in both fields. These fields and stellar activity, when taken together, allow maximum extraction of information from exoplanet space missions. Asteroseismology of the host star has already proved its value in a number of exoplanet systems by its unprecedented precision in determining stellar parameters. In addition, asteroseismology allows the possibility of discovering new exoplanets through time delay studies. The study of the interaction between exoplanets and their host stars opens new windows on various physical processes. In this review I will summarize past and current research in exoplanet asteroseismology and explore some guidelines for the future.

  9. Structure of neutron stars

    International Nuclear Information System (INIS)

    Cheong, C.K.

    1974-01-01

    Structure of neutron stars consisting of a cold and catalyzed superdense matter were investigated by integrating the equations for hydrostatic equilibrium based on the General Relativity theory. The equations of state were obtained with the help of semiempirical nuclear mass formulae. A large phase transition was found between the nuclear and subnuclear density regions. The density phase transition points were calculated as 6.2 x 10 11 and 3.8 x 10 13 g/cm 3 . Due to such a large phase transition, the equation of state practically consists of two parts: The nuclear and subnuclear phases wich are in contact under the thermodynamical equilibrium at the corresponding pressure. Some macroscopic properties of neutron stars are discussed. (Author) [pt

  10. Historical Variable Star Catalogs

    OpenAIRE

    Pagnotta, Ashley; Graur, Or; Murray, Zachary; Kruk, Julia; Christie-Dervaux, Lucien; Chen, Dong Yi

    2015-01-01

    Slides from my talk during one of the Historical Astronomy Division sessions at AAS 225 in Seattle, WA (January 2015). A brief history of the variable star catalogs Henrietta Swan Leavitt and Cecilia Payne-Gaposchkin assembled at Harvard, and the update to them that some of our students at AMNH have done.(Figshare only previews the first few slides. Download the PDF to see all of them!)

  11. Oscillations in neutron stars

    Energy Technology Data Exchange (ETDEWEB)

    Hoeye, Gudrun Kristine

    1999-07-01

    We have studied radial and nonradial oscillations in neutron stars, both in a general relativistic and non-relativistic frame, for several different equilibrium models. Different equations of state were combined, and our results show that it is possible to distinguish between the models based on their oscillation periods. We have particularly focused on the p-, f-, and g-modes. We find oscillation periods of II approx. 0.1 ms for the p-modes, II approx. 0.1 - 0.8 ms for the f-modes and II approx. 10 - 400 ms for the g-modes. For high-order (l (>{sub )} 4) f-modes we were also able to derive a formula that determines II{sub l+1} from II{sub l} and II{sub l-1} to an accuracy of 0.1%. Further, for the radial f-mode we find that the oscillation period goes to infinity as the maximum mass of the star is approached. Both p-, f-, and g-modes are sensitive to changes in the central baryon number density n{sub c}, while the g-modes are also sensitive to variations in the surface temperature. The g-modes are concentrated in the surface layer, while p- and f-modes can be found in all parts of the star. The effects of general relativity were studied, and we find that these are important at high central baryon number densities, especially for the p- and f-modes. General relativistic effects can therefore not be neglected when studying oscillations in neutron stars. We have further developed an improved Cowling approximation in the non-relativistic frame, which eliminates about half of the gap in the oscillation periods that results from use of the ordinary Cowling approximation. We suggest to develop an improved Cowling approximation also in the general relativistic frame. (Author)

  12. Detector limitations, STAR

    Energy Technology Data Exchange (ETDEWEB)

    Underwood, D. G.

    1998-07-13

    Every detector has limitations in terms of solid angle, particular technologies chosen, cracks due to mechanical structure, etc. If all of the presently planned parts of STAR [Solenoidal Tracker At RHIC] were in place, these factors would not seriously limit our ability to exploit the spin physics possible in RHIC. What is of greater concern at the moment is the construction schedule for components such as the Electromagnetic Calorimeters, and the limited funding for various levels of triggers.

  13. Stars of strange matter

    International Nuclear Information System (INIS)

    Bethe, H.A.; Brown, G.E.; Cooperstein, J.

    1987-01-01

    We investigate suggestions that quark matter with strangeness per baryon of order unity may be stable. We model this matter at nuclear matter densities as a gas of close packed Λ-particles. From the known mass of the Λ-particle we obtain an estimate of the energy and chemical potential of strange matter at nuclear densities. These are sufficiently high to preclude any phase transition from neutron matter to strange matter in the region near nucleon matter density. Including effects from gluon exchange phenomenologically, we investigate higher densities, consistently making approximations which underestimate the density of transition. In this way we find a transition density ρ tr > or approx.7ρ 0 , where ρ 0 is nuclear matter density. This is not far from the maximum density in the center of the most massive neutron stars that can be constructed. Since we have underestimated ρ tr and still find it to be ∝7ρ 0 , we do not believe that the transition from neutron to quark matter is likely in neutron stars. Moreover, measured masses of observed neutron stars are ≅1.4 M sun , where M sun is the solar mass. For such masses, the central (maximum) density is ρ c 0 . Transition to quark matter is certainly excluded for these densities. (orig.)

  14. What are the stars?

    CERN Document Server

    Srinivasan, Ganesan

    2014-01-01

    The outstanding question in astronomy at the turn of the twentieth century was: What are the stars and why are they as they are? In this volume, the story of how the answer to this fundamental question was unravelled is narrated in an informal style, with emphasis on the underlying physics. Although the foundations of astrophysics were laid down by 1870, and the edifice was sufficiently built up by 1920, the definitive proof of many of the prescient conjectures made in the 1920s and 1930s came to be established less than ten years ago. This book discusses these recent developments in the context of discussing the nature of the stars, their stability and the source of the energy they radiate.  Reading this book will get young students excited about the presently unfolding revolution in astronomy and the challenges that await them in the world of physics, engineering and technology. General readers will also find the book appealing for its highly accessible narrative of the physics of stars.  “... The reade...

  15. ChromaStarPy: A Stellar Atmosphere and Spectrum Modeling and Visualization Lab in Python

    Science.gov (United States)

    Short, C. Ian; Bayer, Jason H. T.; Burns, Lindsey M.

    2018-02-01

    We announce ChromaStarPy, an integrated general stellar atmospheric modeling and spectrum synthesis code written entirely in python V. 3. ChromaStarPy is a direct port of the ChromaStarServer (CSServ) Java modeling code described in earlier papers in this series, and many of the associated JavaScript (JS) post-processing procedures have been ported and incorporated into CSPy so that students have access to ready-made data products. A python integrated development environment (IDE) allows a student in a more advanced course to experiment with the code and to graphically visualize intermediate and final results, ad hoc, as they are running it. CSPy allows students and researchers to compare modeled to observed spectra in the same IDE in which they are processing observational data, while having complete control over the stellar parameters affecting the synthetic spectra. We also take the opportunity to describe improvements that have been made to the related codes, ChromaStar (CS), CSServ, and ChromaStarDB (CSDB), that, where relevant, have also been incorporated into CSPy. The application may be found at the home page of the OpenStars project: http://www.ap.smu.ca/OpenStars/.

  16. Resolving the Birth of High-Mass Binary Stars

    Science.gov (United States)

    Kohler, Susanna

    2017-02-01

    .The authors model of the geometry of the binary system, including the orientations of the two circumstellar disks (sketch not to scale). [Adapted from Kraus et al. 2017]Fitting models to the observations, Kraus and collaborators find the best-fitting description of the systems geometry and the masses of the components roughly 18 and 20 solar masses, they estimate.By tracing the hot gas in their observations of the system, the authors also determine that the secondary, smaller component is accreting at a higher rate than the larger star. This suggests that the secondary disrupts the accretion stream onto the primary star, channeling the infalling material onto its own disk instead an observation that confirms the prediction of hydrodynamic simulations.IRAS17216-3801 is roughly three times more massive and five times more compact than other high-mass multiple star systems imaged in infrared, and it is the first system in which resolution of its component disks has been possible. These images present an exciting laboratory for studying stardisk interactions and the formation of high-mass multiple systems.CitationS. Kraus et al 2017 ApJL 835 L5. doi:10.3847/2041-8213/835/1/L5

  17. A new family of magnetic stars: the Am stars

    Science.gov (United States)

    Blazère, A.; Neiner, C.; Petit, P.; Lignières, F.

    2016-12-01

    We presented the discovery of an ultra-weak field in three Am stars, β UMa, θ Leo, and Alhena, thanks to ultra-deep spectropolarimetric observations. Two of the three stars of this study shown peculiar magnetic signatures with prominent positive lobes like the one of Sirius A that are not expected in the standard theory of the Zeeman effect. Alhena, contrary to Sirius A, β UMa and θ Leo, show normal signatures. These detections of ultra-weak fields in Am stars suggest the existence of a new family of magnetic intermediate-mass stars: the Am stars. However the various shapes of the signatures required further observation to identify the physical processes at work in these stars. A preliminary explanation is based on microturbulence.

  18. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Echoes from a Dying Star

    Science.gov (United States)

    Kohler, Susanna

    2017-06-01

    When a passing star is torn apart by a supermassive black hole, it emits a flare of X-ray, ultraviolet, and optical light. What can we learn from the infrared echo of a violent disruption like this one?Stellar DestructionOptical (black triangles) and infrared (blue circles and red squares) observations of F010042237. Day 0 marks the day the optical emission peaked. The infrared emission rises steadily through the end of the data. [Dou et al. 2017]Tidal disruption events occur when a star passes within the tidal radius of a supermassive black hole. After tidal forces pull the star apart, much of the stellar matter falls onto the black hole, radiating briefly in X-ray, ultraviolet and optical as it accretes. This signature rise and gradual fall of emission has allowed us to detect dozens of tidal disruption events thus far.One of the recently discovered candidate events is a little puzzling. Not only does the candidate in ultraluminous infrared galaxy F010042237 have an unusual host most disruptions occur in galaxies that are no longer star-forming, in contrast to this one but its optical light curve also shows an unusually long decay time.Now mid-infrared observations of this event have beenpresented by a team of scientists led by Liming Dou (Guangzhou University and Department of Education, Guangdong Province, China), revealing why this disruption is behaving unusually.Schematic of a convex dusty ring (red bows) that absorbs UV photons and re-emits in the infrared. It simultaneously scatters UV and optical photons into our line of sight. The dashed lines illustrate the delays at lags of 60 days, 1, 2, 3, 4, and 5 years. [Adapted from Dou et al. 2017]A Dusty Solution?The optical flare from F010042237s nucleus peaked in 2010, so Dou and collaborators obtained archival mid-infrared data from the WISE and NEOWISE missions from 2010 to 2016. The data show that the galaxy is quiescent in mid-infrared in 2010 but in data from three years later, the infrared emission has

  20. Observing the Sun with NuSTAR

    Science.gov (United States)

    Kohler, Susanna

    2016-07-01

    solar flares?The process of electron acceleration during solar flares is not well understood. When a flare-producing active region is occulted by the solar limb, NuSTAR will able to directly observe the flare loop above the solar surface which is where that acceleration is thought to happen.How is the solar corona heated?The solar corona is a toasty 13 million Kelvin significantly warmer than the ~6000 K solar photosphere. So how is the corona heated? One proposed explanation is that the Suns surface constantly emits tiny nanoflares in active regions, or even in the quiet Sun that are so faint that we havent detected them. But with its high sensitivity, NuSTAR may be able to!The first NuSTAR full-disk mosaic of the Sun. The checkerboard pattern is an artifact of the detectors being hit by particles from active regions outside of the field of view a problem which will be reduced as the Sun enters the upcoming quieter part of the solar cycle. [Adapted from Grefenstette et al. 2016]First ObservationsIn NuSTARs first four observations of the Sun, the team unexpectedly observed a major flare (which unsurprisingly swamped the detectors), watched the emission above an active region that was hidden by the solar limb, stared at a section of quiet Sun near the north solar pole, and composed a full-disk mosaic of the solar surface from 16 12 x 12 tiles.All of these initial observations are currently being carefully analyzed and will be presented in detail in future publications. In the meantime, NuSTAR has demonstrated its effectiveness in detecting faint emission in solar hard X-rays, proving that it will be a powerful tool for heliophysics as well as for astrophysics. We look forward to seeing the future results from this campaign!CitationBrian W. Grefenstette et al 2016 ApJ 826 20. doi:10.3847/0004-637X/826/1/20

  1. Feedback Regulated Star Formation: From Star Clusters to Galaxies

    OpenAIRE

    Dib, Sami

    2011-01-01

    This paper summarises results from semi-analytical modelling of star formation in protocluster clumps of different metallicities. In this model, gravitationally bound cores form uniformly in the clump following a prescribed core formation efficiency per unit time. After a contraction timescale which is equal to a few times their free-fall times, the cores collapse into stars and populate the IMF. Feedback from the newly formed OB stars is taken into account in the form of stellar winds. When ...

  2. First stars X. The nature of three unevolved carbon-enhanced metal-poor stars

    DEFF Research Database (Denmark)

    Sivarani, T.; Beers, T.C.; Bonifacio, P.

    2006-01-01

    Stars: abundances, stars: population II, Galaxy: abundances, stars: AGB and post-AGB Udgivelsesdato: Nov.......Stars: abundances, stars: population II, Galaxy: abundances, stars: AGB and post-AGB Udgivelsesdato: Nov....

  3. AP@home: The Artificial Pancreas Is Now at Home.

    Science.gov (United States)

    Heinemann, Lutz; Benesch, Carsten; DeVries, J Hans

    2016-07-01

    In the past years the development of an artificial pancreas (AP) has made great progress and many activities are ongoing in this area of research. The major step forward made in the last years was moving the evaluation of AP systems from highly controlled experimental conditions to daily life conditions at the home of patients with diabetes; this was also the aim of the European Union-funded AP@home project. Over a time period of 5 years a series of clinical studies were performed that culminated in 2 "final studies" during which an AP system was used by patients in their home environment for 2 or 3 months without supervision by a physician, living their normal lives. Two different versions of the AP system developed within this project were evaluated. A significant improvement in glycated hemoglobin was observed during closed-loop conditions despite the fact that during the control period the patients used the best currently available therapeutic option. In addition, a "single-port AP system" was developed within the project that combines continuous glucose monitoring and insulin infusion at a single tissue site. By using such a combined device the patients not only have to carry one less device around, the number of access points through the skin is also reduced from 2 to 1. In summary, close cooperation of 12 European partners, both academic centers and industry, enabled the development and evaluation of AP systems under daily life conditions. The next step is to develop these into products in cooperation with commercial partners. © 2016 Diabetes Technology Society.

  4. StarDOM: From STAR format to XML

    International Nuclear Information System (INIS)

    Linge, Jens P.; Nilges, Michael; Ehrlich, Lutz

    1999-01-01

    StarDOM is a software package for the representation of STAR files as document object models and the conversion of STAR files into XML. This allows interactive navigation by using the Document Object Model representation of the data as well as easy access by XML query languages. As an example application, the entire BioMagResBank has been transformed into XML format. Using an XML query language, statistical queries on the collected NMR data sets can be constructed with very little effort. The BioMagResBank/XML data and the software can be obtained at http://www.nmr.embl-heidelberg.de/nmr/StarDOM/

  5. Star Formation in Galaxies: Proceedings of a Conference Held in Pasadena, California

    Science.gov (United States)

    1987-05-01

    the SMC. But even in the LMC, enrichment has proceeded much more slowly than in the Milky Way (e.g. Twarog 1980). References to discussions of these...108, Structure and Evolution of the Magellanic Couds, ed. S. v. d. Bergh, and K. S. de Boer (Dordrecht: Reidel), p. 79. Twarog , B. A. 1980, Ap. J., 242...strongly with the derived constant Solar Neighborhood low mass SFR ( Twarog 1980) - hence the star formation process is bimodal in time as well as space (cf

  6. An alternatively spliced mRNA from the AP-2 gene encodes a negative regulator of transcriptional activation by AP-2.

    OpenAIRE

    Buettner, R; Kannan, P; Imhof, A; Bauer, R; Yim, S O; Glockshuber, R; Van Dyke, M W; Tainsky, M A

    1993-01-01

    AP-2 is a retinoic acid-inducible and developmentally regulated activator of transcription. We have cloned an alternative AP-2 transcript (AP-2B) from the human teratocarcinoma cell line PA-1, which encodes a protein differing in the C terminus from the previously isolated AP-2 protein (AP-2A). This protein contains the activation domain of AP-2 and part of the DNA binding domain but lacks the dimerization domain which is necessary for DNA binding. Analysis of overlapping genomic clones spann...

  7. AP1000 - the new standard for nuclear power

    International Nuclear Information System (INIS)

    Lipman, Daniel S.

    2006-01-01

    Full text of publication follows: The AP1000 is the only Generation III+ reactor to receive Final Design Approval (FDA) from the Nuclear Regulatory Commission, and is expected to receive its Design Certification by the end of the year. Building on the proven features of current generation nuclear plants, the AP1000 combines experience with innovation into a design that surpasses current standards of safety and reliability. Use of passive safety features results in a simpler and more compact design that enhances safety, simplifies O and M requirements, and reduces capital and operating costs. At 1117 Mwe, the AP1000 is well suited for almost any grid system and will be fully competitive with combined-cycle gas and comparable fossil fuel plants. The AP1000 is ready to help launch a renaissance in new nuclear plant construction throughout the world. Maturity of Design: In excess of 1300 man-years and $400 million in development funding have been expended on the AP1000. It has undergone extensive, part scale testing at the system, sub-system and component level, in addition to a series of part scale integrated tests. The AP1000 is the most analyzed of the next generation reactors. Simplicity of Design/Economics: The AP1000 uses simplified and innovative passive safety systems to an unprecedented extent. Simplified passive safety systems provide reliable operation, reduced capital costs, and enhanced plant safety with large plant operating margins. The AP1000 features improved reliability through simplicity rather than addition of redundant safety trains. This simpler design is easier and less costly to operate and maintain than larger, more complex plants, while less equipment and smaller buildings translate into lower capital costs and shorter construction durations. After construction, economic benefit will be found in reduced operating and maintenance costs, largely due to reduced operating and maintenance staffing requirements. Construction aspects

  8. First stars evolution and nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Bahena, D. [Institute of Astronomy of the Academy of Sciences, Bocni II 1401, 14131 Praha 4, (Czech Republic); Klapp, J. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico); Dehnen, H. [Fachbereich Physik, Universitat Konstanz, 78457 Konstanz (Germany)]. e-mail: bahen@hotmail.com

    2007-12-15

    The first stars in the universe were massive and luminous with typical masses M {>=} 100M. Metal-free stars have unique physical characteristics and exhibit high effective temperatures and small radii. These so called Population III stars were responsible for the initial enrichment of the intergalactic medium with heavy elements. In this work, we study the structure, evolution and nucleosynthesis of 100, 200, 250 and 300M galactic and pregalactic Population III mass losing stars with metallicities Z 10{sup -6} and Z = 10{sup -9}, during the hydrogen and helium burning phases. Using a stellar evolution code, a system of 10 structure and evolution equations together with boundary conditions, and a set of 30 nuclear reactions, are solved simultaneously, obtaining the star's structure, evolution, isotopic abundances and their ratios. Motivated by recent stability analysis, almost all very massive star (VMS) calculations during the past few years have been performed with no mass loss. However, it has recently been claimed that VMS should have strong mass loss. We present in this work new VMS calculations that includes mass loss. The main difference between zero-metal and metal-enriched stars lies in the nuclear energy generation mechanism. For the first stars, nuclear burning proceeds in a non-standard way. Since Population III stars can reach high central temperatures, this leads to the first synthesis of primary carbon through the 3 {alpha} reaction activating the CNO-cycles. Zero-metal stars produce light elements, such as He, C, N and O. Thus, very massive pregalactic Population III stars experienced self-production of C, either at the zero-age main sequence or in later phases of central hydrogen burning. In advanced evolutionary phases, these stars contribute to the chemical enrichment of the intergalactic medium through supernova explosions. (Author)

  9. Abundances in stars with exoplanets

    OpenAIRE

    Israelian, Garik

    2003-01-01

    Extensive spectroscopic studies of stars with and without planets have concluded that stars hosting planets are significantly more metal-rich than those without planets. More subtle trends of different chemical elements begin to appear as the number of detected extrasolar planetary systems continues to grow. I review our current knowledge concerning the observed abundance trends of various chemical elements in stars with exoplanets and their possible implications.

  10. Fast radio bursts and their possible neutron star origins

    Science.gov (United States)

    Hessels, J. W. T.

    2017-12-01

    The discovery of the ‘Lorimer Burst’, a little over a decade ago, ignited renewed interest in searching for short-duration radio transients (Lorimer et al 2007 Science 318 777). This event is now considered to be the first established Fast Radio Burst (FRB), which is a class of millisecond-duration radio transients (Thornton et al 2013 Science 341 53). The large dispersive delays observed in FRBs distinguish them from the individual bright pulses from Galactic pulsars, and suggests that they originate deep in extragalactic space. Amazingly, FRBs are not rare: the implied event rate ranges up to many thousands of events per sky, per day (Champion et al 2016 MNRAS 460 L30). The fact that only two dozen FRBs have been discovered to date is a consequence of the limited sensitivity and field of view of current radio telescopes (Petroff et al 2016 PASA 33 e045). The precise localization of FRB 121102, the first and currently only FRB observed to repeat (Spitler et al 2014 ApJ 790 101; Spitler et al 2016 Nature 531 202; Scholz et al 2016 ApJ 833 177), has led to the unambiguous identification of its host galaxy and thus proven its extragalactic origin and large energy scale (Chatterjee et al 2017 Nature 541 58; Tendulkar et al 2017 ApJL 834 L7; Marcote et al 2017 ApJL 834 L8). It remains unclear, however, whether all FRBs are capable of repeating [many appear far less active (Petroff et al 2015 MNRAS 454 457)] or whether FRB 121102 implies that there are multiple sub-classes. Regardless, the repetitive nature of FRB 121102 and its localization to within a star-forming region in the host galaxy (Bassa et al 2017 ApJL 843 L8) imply that the bursts might originate from an exceptionally powerful neutron star - one necessarily quite unlike any we have observed in the Milky Way. In these proceedings, I give a very brief introduction to the FRB phenomenon and focus primarily on the insights that FRB 121102 has provided thus far.

  11. Numerical study of rotating relativistic stars

    International Nuclear Information System (INIS)

    Wilson, J.R.

    1975-01-01

    The equations of structure for rotating stars in general relativity are presented and put in a form suitable for computer calculations. The results of equilibrium calculations for supermassive stars, neutron stars, and magnetically supported stars are reported, as are calculations of collapsing, rotating, and magnetized stars in the slowly changing gravitational field approximation. (auth)

  12. The Uhuru star aspect sensor.

    Science.gov (United States)

    Jagoda, N.; Austin, G.; Mickiewicz, S.; Goddard, R.

    1972-01-01

    Description of the star sensor used in the spin-stabilized Uhuru satellite for the purpose of detecting and locating stellar X-ray sources. The star sensor had the capability of detecting fourth-magnitude stars to within 1 arc minute of azimuth and 2 arc minutes of elevation. This was achieved with the aid of a slightly modified 76-mm, f/0.87 Super Farron lens, an 'n' shaped reticle located in the focal plane, and an RCA CF70114F photomultiplier serving as the detection element. The star sensor is composed of three major components - a high-voltage power supply, the photomultiplier, and an amplifier.

  13. The Spacelab IPS Star Simulator

    Science.gov (United States)

    Wessling, Francis C., III

    The cost of doing business in space is very high. If errors occur while in orbit the costs grow and desired scientific data may be corrupted or even lost. The Spacelab Instrument Pointing System (IPS) Star Simulator is a unique test bed that allows star trackers to interface with simulated stars in a laboratory before going into orbit. This hardware-in-the loop testing of equipment on earth increases the probability of success while in space. The IPS Star Simulator provides three fields of view 2.55 x 2.55 degrees each for input into star trackers. The fields of view are produced on three separate monitors. Each monitor has 4096 x 4096 addressable points and can display 50 stars (pixels) maximum at a given time. The pixel refresh rate is 1000 Hz. The spectral output is approximately 550 nm. The available relative visual magnitude range is 2 to 8 visual magnitudes. The star size is less than 100 arc seconds. The minimum star movement is less than 5 arc seconds and the relative position accuracy is approximately 40 arc seconds. The purpose of this paper is to describe the LPS Star Simulator design and to provide an operational scenario so others may gain from the approach and possible use of the system.

  14. The birth of star clusters

    CERN Document Server

    2018-01-01

    All stars are born in groups. The origin of these groups has long been a key question in astronomy, one that interests researchers in star formation, the interstellar medium, and cosmology. This volume summarizes current progress in the field, and includes contributions from both theorists and observers. Star clusters appear with a wide range of properties, and are born in a variety of physical conditions. Yet the key question remains: How do diffuse clouds of gas condense into the collections of luminous objects we call stars? This book will benefit graduate students, newcomers to the field, and also experienced scientists seeking a convenient reference.

  15. Evolution of stars and galaxies

    International Nuclear Information System (INIS)

    Baade, W.

    1975-01-01

    Transcriptions of recorded lectures given by the author have been edited into book form. Topics covered include: historical introduction, classification of galaxies; observation of galaxies; photography of galaxies; the andromeda nebula, spiral structure; dust and gas in galaxies; outline of stellar evolution; the distances to the galaxies; galactic clusters; stellar associations; the T Tauri stars; globular clusters: color-magnitude diagrams; spectra of population II stars; variable stars in globular clusters; elliptical galaxies; irregular galaxies and star formation; the magellanic clouds; the andromeda nebula, photometry; evolution of galaxies; the structure of the galaxy; the galactic nucleus; the galactic disk; and kinematics and evolution of the galaxy. 27 tables, 26 figures

  16. Statistical properties of barium stars

    International Nuclear Information System (INIS)

    Hakkila, J.E.

    1986-01-01

    Barium stars are G- and K-giant stars with atmospheric excesses of s-process elements, and a broadband spectral depression in the blue portion of the spectrum. The strength of the λ4554 Ball line is used as a classification parameter known as the Barium Intensity. They have a mean absolute magnitude of 1.0 and a dispersion of 1.2 magnitudes (assuming a Gaussian distribution in absolute magnitude) as measured from secular and statistical parallaxes. These stars apparently belong to a young-disk population from analyses of both the solar reflex motion and their residual velocity distribution, which implies that they have an upper mass limit of around three solar masses. There is no apparent correlation of barium intensity with either luminosity or kinematic properties. The barium stars appear to be preferentially distributed in the direction of the local spiral arm, but show no preference to associate with or avoid the direction of the galactic center. They do not appear related to either the carbon or S-stars because of these tendencies and because of the stellar population to which each type of star belongs. The distribution in absolute magnitude combined with star count analyses implies that these stars are slightly less numerous than previously believed. Barium stars show infrared excesses that correlate with their barium intensities

  17. The Double Star mission

    Directory of Open Access Journals (Sweden)

    Liu

    2005-11-01

    Full Text Available The Double Star Programme (DSP was first proposed by China in March, 1997 at the Fragrant Hill Workshop on Space Science, Beijing, organized by the Chinese Academy of Science. It is the first mission in collaboration between China and ESA. The mission is made of two spacecraft to investigate the magnetospheric global processes and their response to the interplanetary disturbances in conjunction with the Cluster mission. The first spacecraft, TC-1 (Tan Ce means "Explorer", was launched on 29 December 2003, and the second one, TC-2, on 25 July 2004 on board two Chinese Long March 2C rockets. TC-1 was injected in an equatorial orbit of 570x79000 km altitude with a 28° inclination and TC-2 in a polar orbit of 560x38000 km altitude. The orbits have been designed to complement the Cluster mission by maximizing the time when both Cluster and Double Star are in the same scientific regions. The two missions allow simultaneous observations of the Earth magnetosphere from six points in space. To facilitate the comparison of data, half of the Double Star payload is made of spare or duplicates of the Cluster instruments; the other half is made of Chinese instruments. The science operations are coordinated by the Chinese DSP Scientific Operations Centre (DSOC in Beijing and the European Payload Operations Service (EPOS at RAL, UK. The spacecraft and ground segment operations are performed by the DSP Operations and Management Centre (DOMC and DSOC in China, using three ground station, in Beijing, Shanghai and Villafranca.

  18. Stars of heaven

    CERN Document Server

    Pickover, Clifford A

    2004-01-01

    Do a little armchair space travel, rub elbows with alien life forms, and stretch your mind to the furthest corners of our uncharted universe. With this astonishing guidebook, you don't have to be an astronomer to explore the mysteries of stars and their profound meaning for human existence. Clifford A. Pickover tackles a range of topics from stellar evolution to the fundamental reasons why the universe permits life to flourish. He alternates sections that explain the mysteries of the cosmos with sections that dramatize mind-expanding concepts through a fictional dialog between futuristic human

  19. Hadronic Resonances from STAR

    Directory of Open Access Journals (Sweden)

    Wada Masayuki

    2012-11-01

    Full Text Available The results of resonance particle productions (ρ0, ω, K*, ϕ, Σ*, and Λ* measured by the STAR collaboration at RHIC from various colliding systems and energies are presented. Measured mass, width, 〈pT〉, and yield of those resonances are reviewed. No significant mass shifts or width broadening beyond the experiment uncertainties are observed. New measurements of ϕ and ω from leptonic decay channels are presented. The yields from leptonic decay channels are compared with the measurements from hadronic decay channels and the two results are consistent with each other.

  20. O3 stars

    International Nuclear Information System (INIS)

    Walborn, N.R.

    1982-01-01

    A brief review of the 10 known objects in this earliest spectral class is presented. Two new members are included: HD 64568 in NGC 2467 (Puppis OB2), which provides the first example of an O3 V((f*)) spectrum; and Sk -67 0 22 in the Large Magellanic Cloud, which is intermediate between types O3 If* and WN6-A. In addition, the spectrum of HDE 269810 in the LMC is reclassified as the first of type O3 III (f*). The absolute visual magnitudes of these stars are rediscussed

  1. Erratum: ``Stellar Halo Parameters from 4588 Subdwarfs'' (ApJ, 583, 765 [2003])

    Science.gov (United States)

    Gould, Andrew

    2004-06-01

    An error has been discovered in the computer program that determined the stellar halo parameters using ~4500 halo stars drawn from the revised New Luyten Two-Tenths catalog. None of the major scientific conclusions of that paper are qualitatively altered. In particular, five of the nine velocity-ellipsoid parameters remain consistent with zero within their small errors. However, many individual parameters have changed their values by 1 or 2 σ and a few by more. I explain the nature of the error and give corrected values for the parameters. The ~4500 halo stars analyzed were selected from the revised New Luyten Two-Tenths catalog (A. Gould & S. Salim, ApJ, 583, 765 [2003]; S. Salim & A. Gould, ApJ, 583, 765 [2003]) by demanding that the reduced proper motion (RPM) discriminator,η≡V-5log(μ)-3.1(V-J)-1.47|sinb|-2.73,(1)lie within the secure halo range, 1expressed by a break at a virtually unchanged Vbreak=18.27, but with the completeness at this break point rising to 50%+/-6%. In particular, the motion of the local standard of rest (LSR) relative to the halo isV1=1.5+/-2.2kms-1,V3=0.3+/-2.4kms-1.(3)Hence, as originally claimed, all five velocity-ellipsoid parameters in equations (2) and (3) are consistent with zero. Thus, χ2=3.43 for 5 degrees of freedom, slightly less than the previous value (3.97). This implies that the limits on stellar-halo granularity derived in a subsequent paper from this statistic remain essentially unaltered, being about 2% tighter (see eq. [9] of A. Gould, ApJ, 583, 765 [2003]). Four of the 27 parameters do change by more than 2 σ. Both (c11+Δc11)1/2 and (c22+Δc22)1/2 increase by 4 σ. However, because the Δcii are poorly constrained, these parameter-combination measurements did not give any useful information about the halo, and this remains so with the new determinations. The LF bins at MV=10 and MV=11 each decline by 3 σ, which leaves a somewhat lower but still pronounced peak in the LF at these magnitudes (see Fig. 2). It

  2. APS-U LATTICE DESIGN FOR OFF-AXIS ACCUMULATION

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yipeng; Borland, M.; Lindberg, R.; Sajaev, V.

    2017-06-25

    A 67-pm hybrid-seven-bend achromat (H7BA) lattice is being proposed for a future Advanced Photon Source (APS) multi-bend-achromat (MBA) upgrade project. This lattice design pushes for smaller emittance and requires use of a swap-out (on-axis) injection scheme due to limited dynamic acceptance. Alternate lattice design work has also been performed for the APS upgrade to achieve better beam dynamics performance than the nominal APS MBA lattice, in order to allow off-axis accumulation. Two such alternate H7BA lattice designs, which target a still-low emittance of 90 pm, are discussed in detail in this paper. Although the single-particle-dynamics performance is good, simulations of collective effects indicate that surprising difficulty would be expected accumulating high single-bunch charge in this lattice. The brightness of the 90-pm lattice is also a factor of two lower than the 67-pm H7BA lattice.

  3. AP600 level of automation: United States utility perspective

    International Nuclear Information System (INIS)

    Bekkerman, A.Y.

    1997-01-01

    Design of the AP600 advanced nuclear plant man-machine interface system (M-MIS) is guided by the applicable requirements from the Utility Requirements Document (URD). However, the URD has left certain aspects of the M-MIS to be determined by the designer working together with utilities sponsoring the work. This is particularly true in the case of the level of automation to be designed into the M-MIS. Based on experience from currently operating plants, utilities have specified the identity and roles of personnel in the control room, which has led to establishing a number of level of automation issues for the AP600. The key role of automated computerized procedures in the AP600 automation has been determined and resolved. 5 refs

  4. Star-forming galaxy models: Blending star formation into TREESPH

    Science.gov (United States)

    Mihos, J. Christopher; Hernquist, Lars

    1994-01-01

    We have incorporated star-formation algorithms into a hybrid N-body/smoothed particle hydrodynamics code (TREESPH) in order to describe the star forming properties of disk galaxies over timescales of a few billion years. The models employ a Schmidt law of index n approximately 1.5 to calculate star-formation rates, and explicitly include the energy and metallicity feedback into the Interstellar Medium (ISM). Modeling the newly formed stellar population is achieved through the use of hybrid SPH/young star particles which gradually convert from gaseous to collisionless particles, avoiding the computational difficulties involved in creating new particles. The models are shown to reproduce well the star-forming properties of disk galaxies, such as the morphology, rate of star formation, and evolution of the global star-formation rate and disk gas content. As an example of the technique, we model an encounter between a disk galaxy and a small companion which gives rise to a ring galaxy reminiscent of the Cartwheel (AM 0035-35). The primary galaxy in this encounter experiences two phases of star forming activity: an initial period during the expansion of the ring, and a delayed phase as shocked material in the ring falls back into the central regions.

  5. Al-Sufi's Investigation of Stars, Star Clusters and Nebulae

    Science.gov (United States)

    Hafez, Ihsan; Stephenson, F. R.; Orchiston, W.

    2011-01-01

    The distinguished Arabic astronomer, Al-Sufi (AD 903-986) is justly famous for his Book of the Fixed Stars, an outstanding Medieval treatise on astronomy that was assembled in 964. Developed from Ptolemy's Algamest, but based upon al-Sufi's own stellar observations, the Book of the Fixed Stars has been copied down through the ages, and currently 35 copies are known to exist in various archival repositories around the world. Among other things, this major work contains 55 astronomical tables, plus star charts for 48 constellations. For the first time a long-overdue English translation of this important early work is in active preparation. In this paper we provide biographical material about Al-Sufi and the contents of his Book of the Fixed Stars, before examining his novel stellar magnitude system, and his listing of star clusters and nebulae (including the first-ever mention of the Great Nebula in Andromeda).

  6. Incorporating the APS Catalog of the POSS I and Image Archive in ADS

    Science.gov (United States)

    Humphreys, Roberta M.

    1998-01-01

    The primary purpose of this contract was to develop the software to both create and access an on-line database of images from digital scans of the Palomar Sky Survey. This required modifying our DBMS (called Star Base) to create an image database from the actual raw pixel data from the scans. The digitized images are processed into a set of coordinate-reference index and pixel files that are stored in run-length files, thus achieving an efficient lossless compression. For efficiency and ease of referencing, each digitized POSS I plate is then divided into 900 subplates. Our custom DBMS maps each query into the corresponding POSS plate(s) and subplate(s). All images from the appropriate subplates are retrieved from disk with byte-offsets taken from the index files. These are assembled on-the-fly into a GIF image file for browser display, and a FITS format image file for retrieval. The FITS images have a pixel size of 0.33 arcseconds. The FITS header contains astrometric and photometric information. This method keeps the disk requirements manageable while allowing for future improvements. When complete, the APS Image Database will contain over 130 Gb of data. A set of web pages query forms are available on-line, as well as an on-line tutorial and documentation. The database is distributed to the Internet by a high-speed SGI server and a high-bandwidth disk system. URL is http://aps.umn.edu/IDB/. The image database software is written in perl and C and has been compiled on SGI computers with MIX5.3. A copy of the written documentation is included and the software is on the accompanying exabyte tape.

  7. Past, Present, and Future of AP Chemistry: A Brief History of Course and Exam Alignment Efforts

    Science.gov (United States)

    Magrogan, Serena

    2014-01-01

    As part of the Advanced Placement (AP) Program's commitment to continually enhance alignment with current best practices in college-level learning, the AP Program is currently evaluating and redesigning courses and exams, one of which launched during the 2013-2014 academic school year: AP chemistry. The history of the AP chemistry course and…

  8. AP Report to the Nation: A Closer Look at the Nation and Florida

    Science.gov (United States)

    Sawtell, Ellen A.; Gillie, Jacqueline M.; Smith, Patricia Z.

    2012-01-01

    In February 2012, the College Board published The 8th Annual AP Report to the Nation. This session provides a deeper dive into key information for the United States with an emphasis on Florida, and participants hear how one school in Florida utilizes AP Potential™ to help build their AP Program. Participants also learn about AP participation and…

  9. 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

    (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...

  10. Power supply control units for APS ring magnets

    International Nuclear Information System (INIS)

    Despe, O.D.

    1990-01-01

    The APS storage ring (1104 meters) is divided into 40 sectors. Each sector has 38 magnet coils in five magnet bases. Every alternate sector has an additional quadrupole magnet for skew correction. AR the main dipole magnets, two in each sector are connected in series and fed from one power supply unit. A base is controlled by one power supply control unit (PSCU). Each PSCU is connected to the host computer via a local area network (LAN). This note discusses the hardware configuration of the typical power supply control system used by the APS magnets and the software commands supported by the PSCU

  11. A second-generation superconducting undulator cryostat for the APS

    Science.gov (United States)

    Fuerst, J.; Hasse, Q.; Ivanyushenkov, Y.; Kasa, M.; Shiroyanagi, Y.

    2017-12-01

    A second-generation cryocooler-based cryostat has been designed and built to support a new helically wound superconducting undulator (SCU) magnet for the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). The design represents an evolution of existing SCU cryostats currently in operation in the APS storage ring. Value engineering and lessons learned have resulted in a smaller, cheaper, and simpler cryostat design compatible with existing planar magnets as well as the new helically wound device. We describe heat load and quench response results, design and operational details, and the “build-to-spec” procurement strategy.

  12. NV&EOL G/AP Aerosol Atmospheric Models

    Science.gov (United States)

    1978-09-07

    Aerosol Atmospheric Models o TO Director, Visionics PROm BSIT, VISD (Wt)l7 Sep 78 t CMTI I. In order to adequately model performance of E-0 sensors for...11 2𔃽 073 DELNV-VI SUBJECT: NV&EOL G/AP Aerosol Atmospheric Models 4. The models and fit data for the 3-5 vs. visible curves are the following: r2...corresponding to this fit is shown in Figure 6..... 2 DELNV-VI SUBJECT: NV&EOL G/AP Aerosol Atmospheric Models 9. The following expressions have been

  13. ION EFFECTS IN THE APS PARTICLE ACCUMULATOR RING

    Energy Technology Data Exchange (ETDEWEB)

    Calvey, J.; Harkay, K.; Yao, CY.

    2017-06-25

    Trapped ions in the APS Particle Accumulator Ring (PAR) lead to a positive coherent tune shift in both planes, which increases along the PAR cycle as more ions accumulate. This effect has been studied using an ion simulation code developed at SLAC. After modifying the code to include a realistic vacuum profile, multiple ionization, and the effect of shaking the beam to measure the tune, the simulation agrees well with our measurements. This code has also been used to evaluate the possibility of ion instabilities at the high bunch charge needed for the APS-Upgrade.

  14. Piping benchmark problems for the Westinghouse AP600 Standardized Plant

    International Nuclear Information System (INIS)

    Bezler, P.; DeGrassi, G.; Braverman, J.; Wang, Y.K.

    1997-01-01

    To satisfy the need for verification of the computer programs and modeling techniques that will be used to perform the final piping analyses for the Westinghouse AP600 Standardized Plant, three benchmark problems were developed. The problems are representative piping systems subjected to representative dynamic loads with solutions developed using the methods being proposed for analysis for the AP600 standard design. It will be required that the combined license licensees demonstrate that their solutions to these problems are in agreement with the benchmark problem set

  15. The Stars of Heaven

    Science.gov (United States)

    Pickover, Clifford A.

    2004-05-01

    Do a little armchair space travel, rub elbows with alien life forms, and stretch your mind to the furthest corners of our uncharted universe. With this astonishing guidebook, you don't have to be an astronomer to explore the mysteries of stars and their profound meaning for human existence. Clifford A. Pickover tackles a range of topics from stellar evolution to the fundamental reasons why the universe permits life to flourish. He alternates sections that explain the mysteries of the cosmos with sections that dramatize mind-expanding concepts through a fictional dialog between futuristic humans and their alien peers (who embark on a journey beyond the reader's wildest imagination). This highly accessible and entertaining approach turns an intimidating subject into a scientific game open to all dreamers. Told in Pickover's inimitable blend of fascinating state-of-the-art science and whimsical science fiction, and packed with numerous diagrams and illustrations, The Stars of Heaven unfolds a world of paradox and mystery, one that will intrigue anyone who has ever pondered the night sky with wonder.

  16. Charged boson stars

    Science.gov (United States)

    Pugliese, Daniela; Quevedo, Hernando; Rueda H., Jorge A.; Ruffini, Remo

    2013-07-01

    We study time-independent, spherically symmetric, self-gravitating systems minimally coupled to a scalar field with U(1) gauge symmetry: charged boson stars. We find numerical solutions to the Einstein-Maxwell equations coupled to the relativistic Klein-Gordon equation. It is shown that bound stable configurations exist only for values of the coupling constant less than or equal to a certain critical value. The metric coefficients and the relevant physical quantities, such as the total mass and charge, turn out to be, in general, bound functions of the radial coordinate, reaching their maximum values at a critical value of the scalar field at the origin. We discuss the stability problem from both the quantitative and qualitative point of view. We take into account the electromagnetic contribution to the total mass and investigate the stability issue considering the binding energy per particle. We verify the existence of configurations with positive binding energy in which objects that are apparently bound can be unstable against small perturbations, in full analogy with the effect observed in the mass-radius relation of neutron stars.

  17. Stars Just Got Bigger - A 300 Solar Mass Star Uncovered

    Science.gov (United States)

    2010-07-01

    Using a combination of instruments on ESO's Very Large Telescope, astronomers have discovered the most massive stars to date, one weighing at birth more than 300 times the mass of the Sun, or twice as much as the currently accepted limit of 150 solar masses. The existence of these monsters - millions of times more luminous than the Sun, losing weight through very powerful winds - may provide an answer to the question "how massive can stars be?" A team of astronomers led by Paul Crowther, Professor of Astrophysics at the University of Sheffield, has used ESO's Very Large Telescope (VLT), as well as archival data from the NASA/ESA Hubble Space Telescope, to study two young clusters of stars, NGC 3603 and RMC 136a in detail. NGC 3603 is a cosmic factory where stars form frantically from the nebula's extended clouds of gas and dust, located 22 000 light-years away from the Sun (eso1005). RMC 136a (more often known as R136) is another cluster of young, massive and hot stars, which is located inside the Tarantula Nebula, in one of our neighbouring galaxies, the Large Magellanic Cloud, 165 000 light-years away (eso0613). The team found several stars with surface temperatures over 40 000 degrees, more than seven times hotter than our Sun, and a few tens of times larger and several million times brighter. Comparisons with models imply that several of these stars were born with masses in excess of 150 solar masses. The star R136a1, found in the R136 cluster, is the most massive star ever found, with a current mass of about 265 solar masses and with a birthweight of as much as 320 times that of the Sun. In NGC 3603, the astronomers could also directly measure the masses of two stars that belong to a double star system [1], as a validation of the models used. The stars A1, B and C in this cluster have estimated masses at birth above or close to 150 solar masses. Very massive stars produce very powerful outflows. "Unlike humans, these stars are born heavy and lose weight as

  18. Feedback Regulated Star Formation: From Star Clusters to Galaxies

    Science.gov (United States)

    Dib, S.

    This paper summarises results from semi-analytical modelling of star formation in protocluster clumps of different metallicities. In this model, gravitationally bound cores form uniformly in the clump following a prescribed core formation efficiency per unit time. After a contraction timescale which is equal to a few times their free-fall times, the cores collapse into stars and populate the IMF. Feedback from the newly formed OB stars is taken into account in the form of stellar winds. When the ratio of the effective wind energy of the winds to the gravitational energy of the system reaches unity, gas is removed from the clump and core and star formation are quenched. The power of the radiation driven winds has a strong dependence on metallicity and increases with increasing metallicity. Thus, winds from stars in the high metallicity models lead to a rapid evacuation of the gas from the protocluster clump and to a reduced star formation efficiency, SFE_exp , as compared to their low metallicity counterparts. By combining SFE_exp with the timescales on which gas expulsion occurs, we derive the metallicity dependent star formation rate per unit time in this model as a function of the gas surface density SUMg .This is combined with the molecular gas fraction in order to derive the dependence of the surface density of star formation SUM(SFR) on SUMg . This feedback regulated model of star formation reproduces very well the observed star formation laws extending from low gas surface densities up to the starburst regime. Furthermore, the results show a dependence of SUM(SFR) on metallicity over the entire range of gas surface densities, and can also explain part of the scatter in the observations.

  19. Autosomal recessive spastic tetraplegia caused by AP4M1 and AP4B1 gene mutation: expansion of the facial and neuroimaging features.

    Science.gov (United States)

    Tüysüz, Beyhan; Bilguvar, Kaya; Koçer, Naci; Yalçınkaya, Cengiz; Çağlayan, Okay; Gül, Ece; Sahin, Sezgin; Çomu, Sinan; Günel, Murat

    2014-07-01

    Adaptor protein complex-4 (AP4) is a component of intracellular transportation of proteins, which is thought to have a unique role in neurons. Recently, mutations affecting all four subunits of AP4 (AP4M1, AP4E1, AP4S1, and AP4B1) have been found to cause similar autosomal recessive phenotype consisting of tetraplegic cerebral palsy and intellectual disability. The aim of this study was analyzing AP4 genes in three new families with this phenotype, and discussing their clinical findings with an emphasis on neuroimaging and facial features. Using homozygosity mapping followed by whole-exome sequencing, we identified two novel homozygous mutations in AP4M1 and a homozygous deletion in AP4B1 in three pairs of siblings. Spastic tetraplegia, microcephaly, severe intellectual disability, limited speech, and stereotypic laughter were common findings in our patients. All patients also had similar facial features consisting of coarse and hypotonic face, bitemporal narrowing, bulbous nose with broad nasal ridge, and short philtrum which were not described in patients with AP4M1 and AP4B1 mutations previously. The patients presented here and previously with AP4M1, AP4B1, and AP4E1 mutations shared brain abnormalities including asymmetrical ventriculomegaly, thin splenium of the corpus callosum, and reduced white matter volume. The patients also had hippocampal globoid formation and thin hippocampus. In conclusion, disorders due to mutations in AP4 complex have similar neurological, facial, and cranial imaging findings. Thus, these four genes encoding AP4 subunits should be screened in patients with autosomal recessive spastic tetraplegic cerebral palsy, severe intellectual disability, and stereotypic laughter, especially with the described facial and cranial MRI features. © 2014 Wiley Periodicals, Inc.

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

    DEFF Research Database (Denmark)

    Takada-Hidai, Masahide; Kurtz, Donald W.; Shibahashi, Hiromoto

    2017-01-01

    -eff = 7600 K, log g = 4.2, xi = 3.1 kms(-1) and [Fe/H] = -0.71 dex), the radial and rotation velocities, and elemental abundances were obtained by analysing line strengths and fitting line profiles, which were calculated with a 1D LTE model atmosphere. The main properties of KIC 11145123 are: (1) a low [Fe....../H] = -0.71 +/- 0.11 dex and a high radial velocity of -135.4 +/- 0.2 km s(-1). These are remarkable among late-A stars. Our best asteroseismic models with this low [Fe/H] have slightly high helium abundance and low masses of 1.4 M-circle dot. All of these results strongly suggest that KIC 11145123...... is a Population II blue straggler; (2) the projected rotation velocity confirms the asteroseismically predicted slow rotation of the star; (3) comparisons of abundance patterns between KIC 11145123 and Am, Ap, and blue stragglers show that KIC 11145123 is neither an Am star nor an Ap star, but has abundances...

  1. The STAR-RICH Detector

    CERN Document Server

    Lasiuk, B; Braem, André; Cozza, D; Davenport, M; De Cataldo, G; Dell'Olio, L; Di Bari, D; Di Mauro, A; Dunlop, J C; Finch, E; Fraissard, Daniel; Franco, A; Gans, J; Ghidini, B; Harris, J W; Horsley, M; Kunde, G J; Lasiuk, B; Lesenechal, Y; Majka, R D; Martinengo, P; Morsch, Andreas; Nappi, E; Paic, G; Piuz, François; Posa, F; Raynaud, J; Salur, S; Sandweiss, J; Santiard, Jean-Claude; Satinover, J; Schyns, E M; Smirnov, N; Van Beelen, J; Williams, T D; Xu, Z

    2002-01-01

    The STAR-RICH detector extends the particle idenfication capabilities of the STAR spectrometer for charged hadrons at mid-rapidity. It allows identification of pions and kaons up to ~3 GeV/c and protons up to ~5 GeV/c. The characteristics and performance of the device in the inaugural RHIC run are described.

  2. Magnetic fields in Neutron Stars

    NARCIS (Netherlands)

    Viganò, D.; Pons, J.A.; Miralles, J.A.; Rea, N.; Cenarro, A.J.; Figueras, F.; Hernández-Monteagudo, J.; Bueno, T.; Valdivielso, L.

    2015-01-01

    Isolated neutron stars show a diversity in timing and spectral properties, which has historically led to a classification in different sub-classes. The magnetic field plays a key role in many aspects of the neutron star phenomenology: it regulates the braking torque responsible for their timing

  3. ENERGY STAR Certified Audio Video

    Science.gov (United States)

    Certified models meet all ENERGY STAR requirements as listed in the Version 3.0 ENERGY STAR Program Requirements for Audio Video Equipment that are effective as of May 1, 2013. A detailed listing of key efficiency criteria are available at http://www.energystar.gov/index.cfm?c=audio_dvd.pr_crit_audio_dvd

  4. Chromospheres of Luminous Cool Stars

    Science.gov (United States)

    Dupree, A. K.

    Direct ultraviolet imaging and spectroscopy of Alpha Orionis (Betelgeuse) reveals variable chromospheric structures and mass motions. Spectroscopy also demonstrates the changes of wind opacity, speeds, and mass loss in luminous stars. Cool stars have complex chromospheres that need to be considered in construction of stellar atmospheric models and subsequent spectral analyses.

  5. ENERGY STAR Certified Ceiling Fans

    Science.gov (United States)

    Certified models meet all ENERGY STAR requirements as listed in the Version 3.0 ENERGY STAR Program Requirements for Ceiling Fans that are effective as of April 1, 2012. A detailed listing of key efficiency criteria are available at http://www.energystar.gov/index.cfm?c=ceiling_fans.pr_crit_ceiling_fans

  6. ENERGY STAR Certified Ventilating Fans

    Science.gov (United States)

    Certified models meet all ENERGY STAR requirements as listed in the Version 4.0 ENERGY STAR Program Requirements for Ventilating Fans that are effective as of October 1, 2015. A detailed listing of key efficiency criteria are available at http://www.energystar.gov/index.cfm?c=vent_fans.pr_crit_vent_fans

  7. Opdriftsbaserede modeller for Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten

    Formålet med dette skrift er at få en forhåndsvurdering af mulige effektforøgelser for Wave Star ved anvendelse af aktiv akkumulatordrift. Disse vurderinger baseres på simuleringsmodeller for driften af Wave Star i uregelmæssige bølger. Modellen er udarbejdet i programmeringssproget Delphi og er en...

  8. Pulsations in Subdwarf B Stars

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Subdwarf B stars play a significant role in close binary evolution and in the hot star content of old stellar populations, in particular in giant elliptical galaxies. While the question of their origin poses several problems for stellar evolution theory, one of their most fascinating properties is the presence of ...

  9. Physics of Neutron Star Crusts

    Directory of Open Access Journals (Sweden)

    Chamel Nicolas

    2008-12-01

    Full Text Available The physics of neutron star crusts is vast, involving many different research fields, from nuclear and condensed matter physics to general relativity. This review summarizes the progress, which has been achieved over the last few years, in modeling neutron star crusts, both at the microscopic and macroscopic levels. The confrontation of these theoretical models with observations is also briefly discussed.

  10. Boson Stars and Boson Shells

    Science.gov (United States)

    Kumar, Sanjeev; Kulshreshtha, Usha; Kulshreshtha, Daya Shankar

    2018-03-01

    In this work we present a broad formalism for a study of the models of black holes, boson stars, boson shells and wormholes. The studies of boson stars and boson shells in a theory involving Scalar field, U(1) gauge field and a shelf interacting scalar potential coupled to gravity in the presence of a cosmological constant Λ are presented in details.

  11. KAON CONDENSATION IN NEUTRON STARS.

    Energy Technology Data Exchange (ETDEWEB)

    RAMOS,A.; SCHAFFNER-BIELICH,J.; WAMBACH,J.

    2001-04-24

    We discuss the kaon-nucleon interaction and its consequences for the change of the properties of the kaon in the medium. The onset of kaon condensation in neutron stars under various scenarios as well its effects for neutron star properties are reviewed.

  12. STARS: A Year in Review

    Science.gov (United States)

    Association for the Advancement of Sustainability in Higher Education, 2011

    2011-01-01

    The Sustainability Tracking, Assessment & Rating System[TM] (STARS) is a program of AASHE, the Association for the Advancement of Sustainability in Higher Education. AASHE is a member-driven organization with a mission to empower higher education to lead the sustainability transformation. STARS was developed by AASHE with input and insight from…

  13. Magnetic Fields of Neutron Stars

    Indian Academy of Sciences (India)

    Keywords. Neutron stars: population; magnetic fields; X-ray binaries: evolution; millisecond pulsars: inter-connections. Abstract. This article briefly reviews our current understanding of the evolution of magnetic fields in neutron stars, which basically defines the evolutionary pathways between different observational classes ...

  14. Formation of stars and star clusters in colliding galaxies

    International Nuclear Information System (INIS)

    Belles, Pierre-Emmanuel

    2012-01-01

    Mergers are known to be essential in the formation of large-scale structures and to have a significant role in the history of galaxy formation and evolution. Besides a morphological transformation, mergers induce important bursts of star formation. These starburst are characterised by high Star Formation Efficiencies (SFEs) and Specific Star Formation Rates, i.e., high Star Formation Rates (SFR) per unit of gas mass and high SFR per unit of stellar mass, respectively, compared to spiral galaxies. At all redshifts, starburst galaxies are outliers of the sequence of star-forming galaxies defined by spiral galaxies. We have investigated the origin of the starburst-mode of star formation, in three local interacting systems: Arp 245, Arp 105 and NGC 7252. We combined high-resolution JVLA observations of the 21-cm line, tracing the HI diffuse gas, with UV GALEX observations, tracing the young star-forming regions. We probe the local physical conditions of the Inter-Stellar Medium (ISM) for independent star-forming regions and explore the atomic-to-dense gas transformation in different environments. The SFR/HI ratio is found to be much higher in central regions, compared to outer regions, showing a higher dense gas fraction (or lower HI gas fraction) in these regions. In the outer regions of the systems, i.e., the tidal tails, where the gas phase is mostly atomic, we find SFR/HI ratios higher than in standard HI-dominated environments, i.e., outer discs of spiral galaxies and dwarf galaxies. Thus, our analysis reveals that the outer regions of mergers are characterised by high SFEs, compared to the standard mode of star formation. The observation of high dense gas fractions in interacting systems is consistent with the predictions of numerical simulations; it results from the increase of the gas turbulence during a merger. The merger is likely to affect the star-forming properties of the system at all spatial scales, from large scales, with a globally enhanced turbulence

  15. The AP-1 transcription factor homolog Pf-AP-1 activates transcription of multiple biomineral proteins and potentially participates in Pinctada fucata biomineralization

    Science.gov (United States)

    Zheng, Xiangnan; Cheng, Minzhang; Xiang, Liang; Liang, Jian; Xie, Liping; Zhang, Rongqing

    2015-01-01

    Activator protein-1 (AP-1) is an important bZIP transcription factor that regulates a series of physiological processes by specifically activating transcription of several genes, and one of its well-chartered functions in mammals is participating in bone mineralization. We isolated and cloned the complete cDNA of a Jun/AP-1 homolog from Pinctada fucata and called it Pf-AP-1. Pf-AP-1 had a highly conserved bZIP region and phosphorylation sites compared with those from mammals. A tissue distribution analysis showed that Pf-AP-1 was ubiquitously expressed in P. fucata and the mRNA level of Pf-AP-1 is extremely high in mantle. Pf-AP-1 expression was positively associated with multiple biomineral proteins in the mantle. The luciferase reporter assay in a mammalian cell line showed that Pf-AP-1 significantly up-regulates the transcriptional activity of the promoters of KRMP, Pearlin, and Prisilkin39. Inhibiting the activity of Pf-AP-1 depressed the expression of multiple matrix proteins. Pf-AP-1 showed a unique expression pattern during shell regeneration and pearl sac development, which was similar to the pattern observed for biomineral proteins. These results suggest that the Pf-AP-1 AP-1 homolog is an important transcription factor that regulates transcription of several biomineral proteins simultaneously and plays a role in P. fucata biomineralization, particularly during pearl and shell formation. PMID:26404494

  16. Dark stars in Starobinsky's model

    Science.gov (United States)

    Panotopoulos, Grigoris; Lopes, Ilídio

    2018-01-01

    In the present work we study non-rotating dark stars in f (R ) modified theory of gravity. In particular, we have considered bosonic self-interacting dark matter modeled inside the star as a Bose-Einstein condensate, while as far as the modified theory of gravity is concerned we have assumed Starobinsky's model R +a R2. We solve the generalized structure equations numerically, and we obtain the mass-to-ratio relation for several different values of the parameter a , and for two different dark matter equation-of-states. Our results show that the dark matter stars become more compact in the R-squared gravity compared to general relativity, while at the same time the highest star mass is slightly increased in the modified gravitational theory. The numerical value of the highest star mass for each case has been reported.

  17. Star trackers for attitude determination

    DEFF Research Database (Denmark)

    Liebe, Carl Christian

    1995-01-01

    One problem comes to all spacecrafts using vector information. That is the problem of determining the attitude. This paper describes how the area of attitude determination instruments has evolved from simple pointing devices into the latest technology, which determines the attitude by utilizing...... a CCD camera and a powerful microcomputer. The instruments are called star trackers and they are capable of determining the attitude with an accuracy better than 1 arcsecond. The concept of the star tracker is explained. The obtainable accuracy is calculated, the numbers of stars to be included...... in the star catalogue are discussed and the acquisition of the initial attitude is explained. Finally the commercial market for star trackers is discussed...

  18. Flares on a Bp Star

    Science.gov (United States)

    Mullan, D. J.

    2009-09-01

    Two large X-ray flares have been reported from the direction of a magnetic B2p star (σ Ori E). Sanz-Forcada et al. have suggested that the flares did not occur on the B2p star but on a companion of late spectral type. A star which is a candidate for a late-type flare star near σ Ori E has recently been identified by Bouy et al. However, based on the properties of the flares, and based on a recent model of rotating magnetospheres, we argue that, rather than attributing the two flares to a late-type dwarf, it is a viable hypothesis that the flares were magnetic phenomena associated with the rotating magnetosphere of the B2p star itself.

  19. FLARES ON A Bp STAR

    International Nuclear Information System (INIS)

    Mullan, D. J.

    2009-01-01

    Two large X-ray flares have been reported from the direction of a magnetic B2p star (σ Ori E). Sanz-Forcada et al. have suggested that the flares did not occur on the B2p star but on a companion of late spectral type. A star which is a candidate for a late-type flare star near σ Ori E has recently been identified by Bouy et al. However, based on the properties of the flares, and based on a recent model of rotating magnetospheres, we argue that, rather than attributing the two flares to a late-type dwarf, it is a viable hypothesis that the flares were magnetic phenomena associated with the rotating magnetosphere of the B2p star itself.

  20. The evolution of stable magnetic fields in stars: an analytical approach

    Science.gov (United States)

    Mestel, Leon; Moss, David

    2010-07-01

    The absence of a rigorous proof of the existence of dynamically stable, large-scale magnetic fields in radiative stars has been for many years a missing element in the fossil field theory for the magnetic Ap/Bp stars. Recent numerical simulations, by Braithwaite & Spruit and Braithwaite & Nordlund, have largely filled this gap, demonstrating convincingly that coherent global scale fields can survive for times of the order of the main-sequence lifetimes of A stars. These dynamically stable configurations take the form of magnetic tori, with linked poloidal and toroidal fields, that slowly rise towards the stellar surface. This paper studies a simple analytical model of such a torus, designed to elucidate the physical processes that govern its evolution. It is found that one-dimensional numerical calculations reproduce some key features of the numerical simulations, with radiative heat transfer, Archimedes' principle, Lorentz force and Ohmic decay all playing significant roles.

  1. ChromaStarDB: SQL Database-driven Spectrum Synthesis and More

    Science.gov (United States)

    Short, C. Ian

    2017-09-01

    We present an alternate deployment of the GrayStarServer (now ChromaStarServer (CSS)) pedagogical stellar atmosphere and spectrum synthesis WWW application, namely ChromaStarDB (CSDB), in which the atomic line list used for spectrum synthesis is implemented as an SQL database table rather than as a more conventional byte-data file. This allows for very flexible selection criteria to determine which transitions are extracted from the line list for inclusion in the synthesis, and enables novel pedagogical and research experiments in spectrum synthesis. This line selection flexibility is reflected in the CSDB UI. The database extraction is very fast and would be appropriate for the larger line lists of research-grade modeling codes. We also take the opportunity to present major additions to the ChromaStar and CSS codes that are also reflected in CSDB: (1) TiO band opacity in the JOLA approximation, (2) Metal b - f and Rayleigh scattering opacity, (3) 2D implementation of the flux integral, (4) Improvement of the {n}{{e}} convergence, (5) Expansion of the exo-planet modeling parameters, (6) A red giant template model for the initial guess at the structure, and (7) General improvements to the UI. The applications may be found at the home page of the OpenStar project: http://www.ap.smu.ca/OpenStars/.

  2. Characteristics and design improvement of AP1000 automatic depressurization system

    International Nuclear Information System (INIS)

    Jin Fei

    2012-01-01

    Automatic depressurization system, as a specialty of AP1000 Design, enhances capability of mitigating design basis accidents for plant. Advancement of the system is discussed by comparing with traditional PWR design and analyzing system functions, such as depressurizing and venting. System design improvement during China Project performance is also described. At the end, suggestions for the system in China Project are listed. (author)

  3. 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

  4. The New AP Chemistry Exam: Its Rationale, Content, and Scoring

    Science.gov (United States)

    Price, Paul D.; Kugel, Roger W.

    2014-01-01

    The 2013-2014 academic year marks the rollout of the redesigned advanced placement (AP) chemistry course and exam. There have been many questions as to why the course was redesigned and how the new examination will differ from its legacy version. In this article we give a brief overview of the legacy course and examine why a redesign occurred in…

  5. Multipliers of Ap((0 ,((0 ,((0,∞)) with order convolution

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Introduction. The algebra Ap(G) of elements in L1(G) whose Fourier transforms belong to Lp( ˆG) and the multipliers for these algebras have been studied by various authors [1,7–9]. Let. I = (0, ∞) be the locally compact idempotent commutative topological semigroup with the usual topology and max multiplication and ˆI be ...

  6. SEPTUM MAGNET DESIGN FOR THE APS-U

    Energy Technology Data Exchange (ETDEWEB)

    Abliz, M.; Jaski, M.; Xiao, A.; Wienands, U.; Cease, H.; Borland, M.; Decker, G.; Kerby, J.

    2017-06-25

    The Advanced Photon Source is in the process of upgrading its storage ring from a double-bend to a multi-bend lattice as part of the APS Upgrade Project (APS-U). A swap-out injection scheme is planned for the APS-U to keep a constant beam current and to enable a small dynamic aperture. A septum magnet with a minimum thickness of 2 mm and an injection field of 1.06 T has been designed, delivering the required total deflecting angle is 89 mrad with a ring energy of 6 GeV. The stored beam chamber has an 8 mm x 6 mm super-ellipsoidal aperture. The magnet is straight; however, it is tilted in yaw, roll, and pitch from the stored beam chamber to meet the on axis swap out injection requirements for the APS-U lattice. In order to minimize the leakage field inside the stored beam chamber, four different techniques were utilized in the design. As a result, the horizontal deflecting angle of the stored beam was held to only 5 µrad, and the integrated skew quadrupole inside the stored beam chamber was held to 0.09 T. The detailed techniques that were applied to the design, field multipoles, and resulting trajectories of the injected and stored beams are reported.

  7. Obstetric and vascular APS: same autoantibodies but different diseases?

    Science.gov (United States)

    Meroni, P L; Raschi, E; Grossi, C; Pregnolato, F; Trespidi, L; Acaia, B; Borghi, M O

    2012-06-01

    Beta2 glycoprotein I (β2GPI)-dependent antiphospholipid antibodies (aPLs) are the main pathogenic autoantibody population and at the same time the laboratory diagnostic tool for the antiphospholipid syndrome (APS). These antibodies are responsible for both the vascular and the obstetric manifestations of the syndrome but the pathogenic mechanisms behind these manifestations are not the same. For example, thrombotic events do not appear to play a major role in APS miscarriages and a direct reactivity of β2GPI-dependent aPLs on decidual and trophoblast cells was reported. A local expression of β2GPI on these tissues was reported both in physiological conditions and in APS women, thus explaining the local tropism of the autoantibodies. The two hit hypothesis was suggested to explain why the vascular manifestations of APS may occur only occasionally in spite of the persistent presence of aPLs. This is not apparently the case for the obstetric variant of the syndrome, making the difference even more striking. A different pathogenesis may also provide the rationale for the well-known fact that the vascular and the obstetric manifestations may occur independently although in a minority of cases.

  8. The AP Lever for Boosting Access, Success, and Equity

    Science.gov (United States)

    Roegman, Rachel; Hatch, Thomas

    2016-01-01

    Four New Jersey school districts worked together to increase student achievement by applying a number of strategies focused on getting traditionally underrepresented students to take more AP courses. The districts are members of the New Jersey Network of Superintendents (NJNS), comprising 15 superintendents who work together to develop systemwide…

  9. 76 FR 10269 - AP1000 Design Certification Amendment

    Science.gov (United States)

    2011-02-24

    ... Comments and Accessing Information Comments submitted in writing or in electronic form will be posted on... discussed below: Editorial Changes Westinghouse requested changes to the AP1000 DCD to correct spelling... reduced use of operator actions. In other words, the applicant or licensee must continue to show, with the...

  10. Automated Procurement System (APS) revised project management plan (DS-03)

    Science.gov (United States)

    Murphy, Diane R.

    1995-01-01

    The Project Plan is the governing document for the implementation of the Automated Procurement System (APS). It includes a description of the proposed system, describes the work to be done, establishes a schedule of deliverables, and discusses the major standards and procedures to be followed.

  11. Tead and AP1 Coordinate Transcription and Motility.

    Science.gov (United States)

    Liu, Xiangfan; Li, Huapeng; Rajurkar, Mihir; Li, Qi; Cotton, Jennifer L; Ou, Jianhong; Zhu, Lihua J; Goel, Hira L; Mercurio, Arthur M; Park, Joo-Seop; Davis, Roger J; Mao, Junhao

    2016-02-09

    The Tead family transcription factors are the major intracellular mediators of the Hippo-Yap pathway. Despite the importance of Hippo signaling in tumorigenesis, Tead-dependent downstream oncogenic programs and target genes in cancer cells remain poorly understood. Here, we characterize Tead4-mediated transcriptional networks in a diverse range of cancer cells, including neuroblastoma, colorectal, lung, and endometrial carcinomas. By intersecting genome-wide chromatin occupancy analyses of Tead4, JunD, and Fra1/2, we find that Tead4 cooperates with AP1 transcription factors to coordinate target gene transcription. We find that Tead-AP1 interaction is JNK independent but engages the SRC1-3 co-activators to promote downstream transcription. Furthermore, we show that Tead-AP1 cooperation regulates the activity of the Dock-Rac/CDC42 module and drives the expression of a unique core set of target genes, thereby directing cell migration and invasion. Together, our data unveil a critical regulatory mechanism underlying Tead- and AP1-controlled transcriptional and functional outputs in cancer cells. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  12. Tead and AP1 Coordinate Transcription and Motility

    Directory of Open Access Journals (Sweden)

    Xiangfan Liu

    2016-02-01

    Full Text Available The Tead family transcription factors are the major intracellular mediators of the Hippo-Yap pathway. Despite the importance of Hippo signaling in tumorigenesis, Tead-dependent downstream oncogenic programs and target genes in cancer cells remain poorly understood. Here, we characterize Tead4-mediated transcriptional networks in a diverse range of cancer cells, including neuroblastoma, colorectal, lung, and endometrial carcinomas. By intersecting genome-wide chromatin occupancy analyses of Tead4, JunD, and Fra1/2, we find that Tead4 cooperates with AP1 transcription factors to coordinate target gene transcription. We find that Tead-AP1 interaction is JNK independent but engages the SRC1–3 co-activators to promote downstream transcription. Furthermore, we show that Tead-AP1 cooperation regulates the activity of the Dock-Rac/CDC42 module and drives the expression of a unique core set of target genes, thereby directing cell migration and invasion. Together, our data unveil a critical regulatory mechanism underlying Tead- and AP1-controlled transcriptional and functional outputs in cancer cells.

  13. Arbitrarily primed sequence-related amplified polymorphism (AP ...

    African Journals Online (AJOL)

    Additionally, 80 SRAP primers were used to screen markers in seven plant species (Chinese cabbage, Chinese kale, eggplant, pepper, cucumber, rose and lily), which indicated obvious polymorphism. The primers of AP-SRAP combine simply and reliably. It can overcome the limitation of the number of standard SRAP ...

  14. 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…

  15. Argonne National Laboratory high performance network support of APS experiments

    International Nuclear Information System (INIS)

    Knot, M.J.; McMahon, R.J.

    1996-01-01

    Argonne National Laboratory is currently positioned to provide access to high performance regional and national networks. Much of the impetus for this effort is the anticipated needs of the upcoming experimental program at the APS. Some APS collaborative access teams (CATs) are already pressing for network speed improvements and security enhancements. Requirements range from the need for high data rate, secure transmission of experimental data, to the desire to establish a open-quote open-quote virtual experimental environment close-quote close-quote at their home institution. In the near future, 155 megabit/sec (Mb/s) national and regional asynchronous transfer mode (ATM) networks will be operational and available to APS users. Full-video teleconferencing, virtual presence operation of experiments, and high speed, secure transmission of data are being tested and, in some cases, will be operational. We expect these efforts to enable a substantial improvement in the speed of processing experimental results as well as an increase in convenience to the APS experimentalist. copyright 1996 American Institute of Physics

  16. Proton femtoscopy at STAR

    International Nuclear Information System (INIS)

    Zbroszczyk, H.P.

    2011-01-01

    The analysis of two-particle femtoscopy provides a powerful tool to study the properties of matter created in heavy-ion collisions. Applied to identical and nonidentical hadron pairs, it makes the study of space-time evolution of the source in femtoscopic scale possible. Baryon femtoscopy allows extraction of the radii of produced sources which can be compared to those deduced from identical pion studies, providing additional information about source characteristics. In this paper we present the correlation functions obtained for protons and antiprotons for Au + Au collisions at √ s NN = 62.4 and 200 GeV. On the other hand, as STAR experiment participates in the Beam Energy Scan (BES) program, we present theoretical predictions of p - p , p-bar - p-bar and p - p-bar femtoscopic measurements, based on UrQMD simulation for √ s NN = 5-39 GeV

  17. Star spotting at CERN

    CERN Multimedia

    2008-01-01

    This June, two American celebrities (and physics enthusiasts!) came to CERN. Brian Cox gave Mike Einziger (right), lead guitarist with the rock band Incubus, the star treatment in the ATLAS cavern. Jesse Dylan embraces the spirit of ATLAS! Mike Einziger, lead guitarist with the rock band Incubus, visited CERN on Friday 13 June between concerts in Finland and England. Einziger, a lifelong science enthusiast descended into the ATLAS and CMS caverns and visited the SM18 test magnet facility during his brief tour of CERN. Einziger learned about the LHC through watching online lectures from University of Manchester and ATLAS physicist Brian Cox, and was thrilled to have the chance to see the detectors in person. The musician has created an orchestral piece, inspired in part by the work being done at CERN for the LHC, which will have its debut in Los Angeles on 23 August. Just over a week earlier, Jesse Dylan, Hollywood film director a...

  18. Close binary stars

    International Nuclear Information System (INIS)

    Larsson-Leander, G.

    1979-01-01

    Studies of close binary stars are being persued more vigorously than ever, with about 3000 research papers and notes pertaining to the field being published during the triennium 1976-1978. Many major advances and spectacular discoveries were made, mostly due to increased observational efficiency and precision, especially in the X-ray, radio, and ultraviolet domains. Progress reports are presented in the following areas: observational techniques, methods of analyzing light curves, observational data, physical data, structure and models of close binaries, statistical investigations, and origin and evolution of close binaries. Reports from the Coordinates Programs Committee, the Committee for Extra-Terrestrial Observations and the Working Group on RS CVn binaries are included. (Auth./C.F.)

  19. Reach for the stars

    International Nuclear Information System (INIS)

    Mueller, A.

    1992-01-01

    Nuclear astrophysics is trying to find out why some elements, such as iron, are more abundant in the solar system than others such as gold; and to unravel the processes which lead to different abundances for the elements and their isotopes. The elements originate in the hot cores of giant stars at stages in the cyclic process of stellar nucleosynthesis. Very short lived exotic isotopes which are important in astrophysical processes can be studied at heavy-ion accelerators such as GANIL at Caen in France, where intense beams of high energy heavy ions are being used to synthesize short-lived neutron-rich nuclei and measure their properties. Some of these experiments and the equipment used are described. In particular the isotopic anomaly formed in calcium where calcium-46, which should be more abundant, is actually less abundant in the Solar System. (UK)

  20. VizieR Online Data Catalog: HST photometry of stars in HD 97950 (Pang+, 2016)

    Science.gov (United States)

    Pang, X.; Pasquali, A.; Grebel, E. K.

    2016-07-01

    The HD97950 cluster and its immediate surroundings in the giant HII region NGC3603 were observed with the Hubble Space Telescope (HST). The ultraviolet (UV) data were taken with the High Resolution Channel (HRC) of the Advanced Camera for Surveys (ACS) in 2005 (GO 10602, PI: Jesus Maiz Apellaniz) through the F220W, F250W, F330W, and F435W filters. The HRC is characterized by a spatial resolution of 0.03"/pixel and a field of view of 29''*25''. The optical observations were carried out with the Wide Field and Planetary Camera 2 (WFPC2) in two epochs: 1997 (GO 6763, PI: Laurent Drissen) and 2007 (GO 11193, PI: Wolfgang Brandner) through the F555W, F675W, and F814W filters. The Planetary Camera (PC) chip was centered on the cluster (0.045"/pixel, 40''*40'') for both programs. Pang et al. 2013 (cat. J/ApJ/764/73) reduced the two-epoch WFPC2 data and identified more than 400 member stars on the PC chip via relative proper motions. Of these member stars, 142 are in common between the HRC and PC images and thus have UV and optical photometry available (see Table1). Among the HD97950 cluster member stars determined from relative proper motions (Pang et al. 2013, cat. J/ApJ/764/73, Table2), there are five main-sequence (MS) stars located in the cluster with projected distances of r<0.7pc from the center, for which there are also spectral types available from Table3 of Melena et al. (2008AJ....135..878M). The photometry of these five MS stars is presented in Table2. The individual color excesses and extinctions of the member main sequence stars are listed in Table3. (3 data files).

  1. Rotating relativistic neutron stars

    Energy Technology Data Exchange (ETDEWEB)

    Weber, F.; Glendenning, N.K.

    1991-07-21

    Models of rotating neutron stars are constructed in the framework of Einstein's theory of general relativity. For this purpose a refined version of Hartle's method is applied. The properties of these objects, e.g. gravitational mass, equatorial and polar radius, eccentricity, red- and blueshift, quadrupole moment, are investigated for Kepler frequencies of 4000 s{sup {minus}1} {le} {Omega}{sub K} {le} 9000 s{sup {minus}1}. Therefore a self-consistency problem inherent in the determination of {Omega}{sub K} must be solved. The investigation is based on neutron star matter equations of state derived from the relativistic Martin-Schwinger hierarch of coupled Green's functions. By means of introducing the Hartree, Hartree-Fock, and ladder ({Lambda}) approximations, models of the equation of state derived. A special feature of the latter approximation scheme is the inclusion of dynamical two-particle correlations. These have been calculated from the relativistic T-matrix applying both the HEA and Bonn meson-exchange potentials of the nucleon-nucleon force. The nuclear forces of the former two treatments are those of the standard scalar-vector-isovector model of quantum hadron dynamics, with parameters adjusted to the nuclear matter data. An important aspect of this work consists in testing the compatibility of different competing models of the nuclear equation of state with data on pulsar periods. By this the fundamental problem of nuclear physics concerning the behavior of the equation of state at supernuclear densities can be treated.

  2. The Destructive Birth of Massive Stars and Massive Star Clusters

    Science.gov (United States)

    Rosen, Anna; Krumholz, Mark; McKee, Christopher F.; Klein, Richard I.; Ramirez-Ruiz, Enrico

    2017-01-01

    Massive stars play an essential role in the Universe. They are rare, yet the energy and momentum they inject into the interstellar medium with their intense radiation fields dwarfs the contribution by their vastly more numerous low-mass cousins. Previous theoretical and observational studies have concluded that the feedback associated with massive stars' radiation fields is the dominant mechanism regulating massive star and massive star cluster (MSC) formation. Therefore detailed simulation of the formation of massive stars and MSCs, which host hundreds to thousands of massive stars, requires an accurate treatment of radiation. For this purpose, we have developed a new, highly accurate hybrid radiation algorithm that properly treats the absorption of the direct radiation field from stars and the re-emission and processing by interstellar dust. We use our new tool to perform a suite of three-dimensional radiation-hydrodynamic simulations of the formation of massive stars and MSCs. For individual massive stellar systems, we simulate the collapse of massive pre-stellar cores with laminar and turbulent initial conditions and properly resolve regions where we expect instabilities to grow. We find that mass is channeled to the massive stellar system via gravitational and Rayleigh-Taylor (RT) instabilities. For laminar initial conditions, proper treatment of the direct radiation field produces later onset of RT instability, but does not suppress it entirely provided the edges of the radiation-dominated bubbles are adequately resolved. RT instabilities arise immediately for turbulent pre-stellar cores because the initial turbulence seeds the instabilities. To model MSC formation, we simulate the collapse of a dense, turbulent, magnetized Mcl = 106 M⊙ molecular cloud. We find that the influence of the magnetic pressure and radiative feedback slows down star formation. Furthermore, we find that star formation is suppressed along dense filaments where the magnetic field is

  3. APS beamline standard components handbook. Version 1.1

    Energy Technology Data Exchange (ETDEWEB)

    Kuzay, T.M.

    1992-01-01

    It is clear that most Advanced Photon Source (APS) Collaborative Access Team (CAT) members would like to concentrate on designing specialized equipment related to their scientific programs rather than on routine or standard beamline components. Thus, an effort is in progress at the APS to identify standard and modular components of APS beamlines. Identifying standard components is a nontrivial task because these components should support diverse beamline objectives. To assist with this effort, the APS has obtained advice and help from a Beamline Standardization and Modularization Committee consisting of experts in beamline design, construction, and operation. The staff of the Experimental Facilities Division identified various components thought to be standard items for beamlines, regardless of the specific scientific objective of a particular beamline. A generic beamline layout formed the basis for this identification. This layout is based on a double-crystal monochromator as the first optical element, with the possibility of other elements to follow. Pre-engineering designs were then made of the identified standard components. The Beamline Standardization and Modularization Committee has reviewed these designs and provided very useful input regarding the specifications of these components. We realize that there will be other configurations that may require special or modified components. This Handbook in its current version (1.1) contains descriptions, specifications, and pre-engineering design drawings of these standard components. In the future, the APS plans to add engineering drawings of identified standard beamline components. Use of standard components should result in major cost reductions for CATs in the areas of beamline design and construction.

  4. STAR-POLYMER -- COLLOID MIXTURES

    Directory of Open Access Journals (Sweden)

    J.Dzubiella

    2002-01-01

    Full Text Available Recent results in theory and simulation of star-polymer--colloid mixtures are reviewed. We present the effective interaction between hard, colloidal particles and star polymers in a good solvent derived by monomer-resolved Molecular Dynamics simulations and theoretical arguments. The relevant parameters are the size ratio q between the stars and the colloids, as well as the number of polymeric arms f (functionality attached to the common center of the star. By covering a wide range of q's ranging from zero (star against a flat wall up to about 0.5, we establish analytical forms for the star-colloid interaction which are in excellent agreement with simulation results. By employing this cross interaction and the effective interactions between stars and colloids themselves, a demixing transition in the fluid phase is observed and systematically investigated for different arm numbers and size ratios. The demixing binodals are compared with experimental observations and found to be consistent. Furthermore, we map the full two-component system on an effective one-component description for the colloids, by inverting the two-component Ornstein-Zernike equations. Some recent results for the depletion interaction and freezing transitions are shown.

  5. PALFA Discovers Neutron Stars on a Collision Course

    Science.gov (United States)

    Kohler, Susanna

    2018-03-01

    location to high precision and establish additional parameters of the system.PSR J1946+2052 is a system of extremes. The binarys total mass is found to be 2.5 solar masses, placing it among the lightest binary-neutron-star systems known. Its orbital period is the shortest weve observed, and the two neutron stars are on track to merge in less time than any other known neutron-star binaries: in just 46 million years. When the two stars reach the final stages of their merger, the effects of the pulsars rapid spin on the gravitational-wave signal will be the largest of any such system discovered to date.More Tests of General RelativityWhat can PSR J1946+2052 do for us? This extreme system will be especially useful as a gravitational laboratory. Continued observations of PSR J1946+2052 will pin down with unprecedented precision parameters like the Einstein delay and the rate of decay of the binarys orbit due to the emission of gravitational waves, testing the predictions of general relativity to an order of magnitude higher precision than was possible before.As we expect there to be thousands of systems like PSR J1946+2052 in our galaxy alone, better understanding this binary and finding more like it continue to be important steps toward interpreting compact-object merger observations in the future.CitationK. Stovall et al 2018 ApJL 854 L22. doi:10.3847/2041-8213/aaad06

  6. Aviation Safety Program: Weather Accident Prevention (WxAP) Development of WxAP System Architecture And Concepts of Operation

    Science.gov (United States)

    Grantier, David

    2003-01-01

    This paper presents viewgraphs on the development of the Weather Accident Prevention (WxAP) System architecture and Concept of Operation (CONOPS) activities. The topics include: 1) Background Information on System Architecture/CONOPS Activity; 2) Activity Work in Progress; and 3) Anticipated By-Products.

  7. New illustrated stars and planets

    CERN Document Server

    Cooper, Chris; Nicolson, Iain; Stott, Carole

    2002-01-01

    Stars & Plantes, written by experts and popular science writers, is a comprehensive overview of our Universe - what is it, where it came from and how we discovered it. This intriguing, information-rich new reference book contains over 300 stunning images from the Hubble Telescope and leading observatories from around the world as well as diagrams to explain the finer points of theory. With extensive sections on everything from the Solar System to how stars form Stars & Planets will appeal to beginners and the serious stargazer alike.

  8. Functional analysis of the two Brassica AP3 genes involved in apetalous and stamen carpelloid phenotypes.

    Directory of Open Access Journals (Sweden)

    Yanfeng Zhang

    Full Text Available The Arabidopsis homeotic genes APETALA3 (AP3 and PISTILLATA (PI are B genes which encode MADS-box transcription factors and specify petal and stamen identities. In the current study, the stamen carpelloid (SC mutants, HGMS and AMS, of B. rapa and B. napus were investigated and two types of AP3 genes, B.AP3.a and B.AP3.b, were functional characterized. B.AP3.a and B.AP3.b share high similarity in amino acid sequences except for 8 residues difference located at the C-terminus. Loss of this 8 residues in B.AP3.b led to the change of PI-derived motifs. Meanwhile, B.AP3.a specified petal and stamen development, whereas B.AP3.b only specified stamen development. In B. rapa, the mutations of both genes generated the SC mutant HGMS. In B. napus that contained two B.AP3.a and two B.AP3.b, loss of the two B.AP3.a functions was the key reason for the apetalous mutation, however, the loss-of-function in all four AP3 was related to the SC mutant AMS. We inferred that the 8 residues or the PI-derived motif in AP3 gene probably relates to petal formation.

  9. Terrestrial Planet Formation Around Individual Stars Within Binary Star Systems

    OpenAIRE

    Quintana, Elisa V.; Adams, Fred C.; Lissauer, Jack J.; Chambers, John E.

    2007-01-01

    We calculate herein the late stages of terrestrial planet accumulation around a solar type star that has a binary companion with semimajor axis larger than the terrestrial planet region. We perform more than one hundred simulations to survey binary parameter space and to account for sensitive dependence on initial conditions in these dynamical systems. As expected, sufficiently wide binaries leave the planet formation process largely unaffected. As a rough approximation, binary stars with per...

  10. Star-formation rate in compact star-forming galaxies

    Science.gov (United States)

    Izotova, I. Y.; Izotov, Y. I.

    2018-03-01

    We use the data for the Hβ emission-line, far-ultraviolet (FUV) and mid-infrared 22 μm continuum luminosities to estimate star formation rates averaged over the galaxy lifetime for a sample of about 14000 bursting compact star-forming galaxies (CSFGs) selected from the Data Release 12 (DR12) of the Sloan Digital Sky Survey (SDSS). The average coefficient linking and the star formation rate SFR0 derived from the Hβ luminosity at zero starburst age is found to be 0.04. We compare s with some commonly used SFRs which are derived adopting a continuous star formation during a period of {˜} 100 Myr, and find that the latter ones are 2-3 times higher. It is shown that the relations between SFRs derived using a geometric mean of two star-formation indicators in the UV and IR ranges and reduced to zero starburst age have considerably lower dispersion compared to those with single star-formation indicators. We suggest that our relations for determination are more appropriate for CSFGs because they take into account a proper temporal evolution of their luminosities. On the other hand, we show that commonly used SFR relations can be applied for approximate estimation within a factor of {˜} 2 of the averaged over the lifetime of the bursting compact galaxy.

  11. EMACSS: Evolve Me A Cluster of StarS

    Science.gov (United States)

    Alexander, Poul E. R.; Gieles, Mark

    2012-03-01

    The star cluster evolution code Evolve Me A Cluster of StarS (EMACSS) is a simple yet physically motivated computational model that describes the evolution of some fundamental properties of star clusters in static tidal fields. The prescription is based upon the flow of energy within the cluster, which is a constant fraction of the total energy per half-mass relaxation time. According to Henon's predictions, this flow is independent of the precise mechanisms for energy production within the core, and therefore does not require a complete description of the many-body interactions therein. Dynamical theory and analytic descriptions of escape mechanisms is used to construct a series of coupled differential equations expressing the time evolution of cluster mass and radius for a cluster of equal-mass stars. These equations are numerically solved using a fourth-order Runge-Kutta integration kernel; the results were benchmarked against a data base of direct N-body simulations. EMACSS is publicly available and reproduces the N-body results to within 10 per cent accuracy for the entire post-collapse evolution of star clusters.

  12. The Neutron Star Zoo

    Science.gov (United States)

    Harding, Alice K.

    2014-01-01

    Neutron stars are a very diverse population, both in their observational and their physical properties. They prefer to radiate most of their energy at X-ray and gamma-ray wavelengths. But whether their emission is powered by rotation, accretion, heat, magnetic fields or nuclear reactions, they are all different species of the same animal whose magnetic field evolution and interior composition remain a mystery. This article will broadly review the properties of inhabitants of the neutron star zoo, with emphasis on their high-energy emission. XXX Neutron stars are found in a wide variety of sources, displaying an amazing array of behavior. They can be isolated or in binary systems, accreting, heating, cooling, spinning down, spinning up, pulsing, flaring and bursting. The one property that seems to determine their behavior most strongly is their magnetic field strength, structure and evolution. The hot polar caps, bursts and flares of magnetars are likely due to the rapid decay and twisting of their superstrong magnetic fields, whose very existence requires some kind of early dynamo activity. The intermediate-strength magnetic fields of RPPs determines their spin-down behavior and radiation properties. However, the overlap of the magnetar and RPP populations is not understood at present. Why don't high-field RPPs burst or flare? Why don't lower-field magnetars sometimes behave more like RPPs? INS may be old magnetars whose high fields have decayed, but they do not account for the existence of younger RPPs with magnetar-strength fields. Not only the strength of the magnetic field but also its configuration may be important in making a NS a magnetar or a RPP. Magnetic field decay is a critical link between other NS populations as well. "Decay" of the magnetic field is necessary for normal RPPs to evolve into MSPs through accretion and spin up in LMXBs. Some kind of accretion-driven field reduction is the most likely mechanism, but it is controversial since it is not

  13. A Heavy Flavor Tracker for STAR

    International Nuclear Information System (INIS)

    Xu, Z.; Chen, Y.; Kleinfelder, S.; Koohi, A.; Li, S.; Huang, H.; Tai, A.; Kushpil, V.; Sumbera, M.; Colledani, C.; Dulinski, W.; Himmi, A.; Hu, C.; Shabetai, A.; Szelezniak, M.; Valin, I.; Winter, M.; Surrow, B.; Van Nieuwenhuizen, G.; Bieser, F.; Gareus, R.; Greiner, L.; Lesser, F.; Matis, H.S.; Oldenburg, M.; Ritter, H.G.; Pierpoint, L.; Retiere, F.; Rose, A.; Schweda, K.; Sichtermann, E.; Thomas, J.H.; Wieman, H.; Yamamoto, E.; Kotov, I.

    2005-01-01

    We propose to construct a Heavy Flavor Tracker (HFT) for the STAR experiment at RHIC. The HFT will bring new physics capabilities to STAR and it will significantly enhance the physics capabilities of the STAR detector at central rapidities. The HFT will ensure that STAR will be able to take heavy flavor data at all luminosities attainable throughout the proposed RHIC II era

  14. A Heavy Flavor Tracker for STAR

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Z.; Chen, Y.; Kleinfelder, S.; Koohi, A.; Li, S.; Huang, H.; Tai, A.; Kushpil, V.; Sumbera, M.; Colledani, C.; Dulinski, W.; Himmi,A.; Hu, C.; Shabetai, A.; Szelezniak, M.; Valin, I.; Winter, M.; Miller,M.; Surrow, B.; Van Nieuwenhuizen G.; Bieser, F.; Gareus, R.; Greiner,L.; Lesser, F.; Matis, H.S.; Oldenburg, M.; Ritter, H.G.; Pierpoint, L.; Retiere, F.; Rose, A.; Schweda, K.; Sichtermann, E.; Thomas, J.H.; Wieman, H.; Yamamoto, E.; Kotov, I.

    2005-03-14

    We propose to construct a Heavy Flavor Tracker (HFT) for theSTAR experiment at RHIC. The HFT will bring new physics capabilities toSTAR and it will significantly enhance the physics capabilities of theSTAR detector at central rapidities. The HFT will ensure that STAR willbe able to take heavy flavor data at all luminosities attainablethroughout the proposed RHIC II era.

  15. A Heavy Flavor Tracker for STAR

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Z.; Chen, Y.; Kleinfelder, S.; Koohi, A.; Li, S.; Huang, H.; Tai, A.; Kushpil, V.; Sumbera, M.; Colledani, C.; Dulinski, W.; Himmi,A.; Hu, C.; Shabetai, A.; Szelezniak, M.; Valin, I.; Winter, M.; Surrow,B.; Van Nieuwenhuizen, G.; Bieser, F.; Gareus, R.; Greiner, L.; Lesser,F.; Matis, H.S.; Oldenburg, M.; Ritter, H.G.; Pierpoint, L.; Retiere, F.; Rose, A.; Schweda, K.; Sichtermann, E.; Thomas, J.H.; Wieman, H.; Yamamoto, E.; Kotov, I.

    2005-03-14

    We propose to construct a Heavy Flavor Tracker (HFT) for the STAR experiment at RHIC. The HFT will bring new physics capabilities to STAR and it will significantly enhance the physics capabilities of the STAR detector at central rapidities. The HFT will ensure that STAR will be able to take heavy flavor data at all luminosities attainable throughout the proposed RHIC II era.

  16. Probing thermonuclear burning on accreting neutron stars

    NARCIS (Netherlands)

    Keek, L.

    2008-01-01

    Neutron stars are the most compact stars that can be directly observed, which makes them ideal laboratories to study physics at extreme densities. Neutron stars in low-mass X-ray binaries accrete hydrogen and helium from a lower-mass companion star through Roche lobe overflow. This matter undergoes

  17. Star patterns on lake ice

    Science.gov (United States)

    Tsai, Victor C.; Wettlaufer, J. S.

    2007-06-01

    Star patterns, reminiscent of a wide range of diffusively controlled growth forms from snowflakes to Saffman-Taylor fingers, are ubiquitous features of ice-covered lakes. Despite the commonality and beauty of these “lake stars,” the underlying physical processes that produce them have not been explained in a coherent theoretical framework. Here we describe a simple mathematical model that captures the principal features of lake-star formation; radial fingers of (relatively warm) water-rich regions grow from a central source and evolve through a competition between thermal and porous media flow effects in a saturated snow layer covering the lake. The number of star arms emerges from a stability analysis of this competition and the qualitative features of this meter-scale natural phenomenon are captured in laboratory experiments.

  18. Bob Dylan, the Ordinary Star

    Directory of Open Access Journals (Sweden)

    Laure Bouquerel

    2007-03-01

    Full Text Available This article provides a study of Bob Dylan’s public image as a “star” performer and examines what Dylan represented for his audiences with respect to the challenges of 1960s counterculture. This study focuses primarily on the image of Dylan in D. A. Pennebaker’s documentary film Don’t Look Back, which portrays Dylan when the star is only 23. A study of Pennebaker’s film shows how the filmmaker captures the paradox of Dylan’s star popularity in his refusal to portray the star, not only as a personal struggle, but as a cultural contradiction. The author further identifies a formal link between Dylan’s portrayal of the ordinary star and the minimalist aesthetic of cinéma vérité.

  19. Theory of neutron star magnetospheres

    CERN Document Server

    Curtis Michel, F

    1990-01-01

    An incomparable reference for astrophysicists studying pulsars and other kinds of neutron stars, "Theory of Neutron Star Magnetospheres" sums up two decades of astrophysical research. It provides in one volume the most important findings to date on this topic, essential to astrophysicists faced with a huge and widely scattered literature. F. Curtis Michel, who was among the first theorists to propose a neutron star model for radio pulsars, analyzes competing models of pulsars, radio emission models, winds and jets from pulsars, pulsating X-ray sources, gamma-ray burst sources, and other neutron-star driven phenomena. Although the book places primary emphasis on theoretical essentials, it also provides a considerable introduction to the observational data and its organization. Michel emphasizes the problems and uncertainties that have arisen in the research as well as the considerable progress that has been made to date.

  20. Children's Literature on Neutron Stars

    Science.gov (United States)

    Struck, James

    Children's literature is simple discussion of complicated issues. Neutron stars are discussed in several children's books. Using libraries in Chicago, I will review children's books on neutron stars and compare the literature to literature from scientific discussions of neutron stars on sites like the Chandra site, Hubble Space Telescope site and NASA site. The result will be a discussion of problems and issues involved in discussion of neutron stars. Do children's books leave material out? Do children's books discuss recent observations? Do children's books discuss anything discredited or wrong? How many children's books are in resources like World Cat, the Library of Congress catalog, and the Chicago Public Library catalog? Could children's books be useful to present some of your findings or observations or projects? Children's books are useful for both children and scientist as they present simplified discussion of topics, although sometimes issues are simplified too much.

  1. ENERGY STAR Certified Products - Lighting

    Data.gov (United States)

    U.S. Environmental Protection Agency — This data set contains a simplified list of all currently certified ENERGY STAR Lighting models with basic model information collected across all product categories...

  2. A STAR in the making

    Science.gov (United States)

    2017-05-01

    Entrepreneur Richard Dinan - a former star of the UK reality-TV programme Made in Chelsea - founded the firm Applied Fusion Systems in 2014. The company has now released its first blueprint for a spherical fusion tokamak.

  3. Measurements of ground motion and magnet vibrations at the APS

    International Nuclear Information System (INIS)

    Shiltsev, V.

    1996-01-01

    This article presents results of ground motion and magnet vibrations measurements at the Advanced Photon Source. The experiments were done over a wide, frequency range (0-05-100 Hz) with the use of SM-3KV-type seismic probes from the Budker Institute of Nuclear Physics (Russia). Spectral power densities of vertical and horizontal motions of the APS hall floor and quadrupoles on regular supports were obtained. Also investigated were magnet vibrations induced by designed cooling water flow and spectral characteristics of spatial correlation of the quadrupole vibrations at different sectors of the ring. The influence of personnel activity in the hall and traffic under the ring on the slow motion of storage ring elements were observed. Amplitudes of vibrations at the APS are compared with results of seismic measurements at some other accelerators

  4. Measurements of ground motion and magnets vibrations at the APS

    International Nuclear Information System (INIS)

    Shil'tsev, V.D.

    1994-01-01

    This article presents results of ground motion and magnets vibrations measurements at the Advanced Photon Source. The experiments were done over wide frequency range 0.05-100 Hz with use of SM-3KV type seismic probes from Budker Institute of Nuclear Physics (Russia). Spectral power densities of vertical and horizontal motions of the APS hall floor and quadrupoles on regular supports were obtained. There were also investigated magnets vibrations induced by designed cooling water flow and spectral characteristics of spatial correlation of the quads vibration at different sectors of the ring. Influence of personnel activity in the hall and traffic under the ring on slow motion of storage ring elements were observed. Amplitudes of vibrations at the APS are compared with results of seismic measurements at some other accelerators. 9 refs.; 10 figs.; 1 tab

  5. Airborne Precision Spacing (APS) Dependent Parallel Arrivals (DPA)

    Science.gov (United States)

    Smith, Colin L.

    2012-01-01

    The Airborne Precision Spacing (APS) team at the NASA Langley Research Center (LaRC) has been developing a concept of operations to extend the current APS concept to support dependent approaches to parallel or converging runways along with the required pilot and controller procedures and pilot interfaces. A staggered operations capability for the Airborne Spacing for Terminal Arrival Routes (ASTAR) tool was developed and designated as ASTAR10. ASTAR10 has reached a sufficient level of maturity to be validated and tested through a fast-time simulation. The purpose of the experiment was to identify and resolve any remaining issues in the ASTAR10 algorithm, as well as put the concept of operations through a practical test.

  6. Real-time orbit feedback at the APS

    International Nuclear Information System (INIS)

    Carwardine, J.

    1998-01-01

    A real-time orbit feedback system has been implemented at the Advanced Photon Source in order to meet the stringent orbit stability requirements. The system reduces global orbit motion below 30Hz by a factor of four to below 5 microm rms horizontally and 2 microm rms vertically. This paper focuses on dynamic orbit stability and describes the all-digital orbit feedback system that has been implemented at the APS. Implementation of the global orbit feedback system is described and its latest performance is presented. Ultimately, the system will provide local feedback at each x-ray source point using installed photon BPMs to measure x-ray beam position and angle directly. Technical challenges associated with local feedback and with dynamics of the associated corrector magnets are described. The unique diagnostic capabilities provided by the APS system are discussed with reference to their use in identifying sources of the underlying orbit motion

  7. STAR Vertex Detector Upgrade Development

    Energy Technology Data Exchange (ETDEWEB)

    Greiner, Leo C.; Matis, Howard S.; Stezelberger, Thorsten; Vu,Chinh Q.; Wieman, Howard; Szelezniak, Michal; Sun, Xiangming

    2008-01-28

    We report on the development and prototyping efforts undertaken with the goal of producing a micro-vertex detector for the STAR experiment at the RHIC accelerator at BNL. We present the basic detector requirements and show a sensor development path, conceptual mechanical design candidates and readout architecture. Prototyping and beam test results with current generation MimoSTAR-2 sensors and a readout system featuring FPGA based on-the-fly hit finding and data sparsification are also presented.

  8. STAR Vertex Detector Upgrade Development

    International Nuclear Information System (INIS)

    Greiner, Leo C.; Matis, Howard S.; Stezelberger, Thorsten; Vu, Chinh Q.; Wieman, Howard; Szelezniak, Michal; Sun, Xiangming

    2008-01-01

    We report on the development and prototyping efforts undertaken with the goal of producing a micro-vertex detector for the STAR experiment at the RHIC accelerator at BNL. We present the basic detector requirements and show a sensor development path, conceptual mechanical design candidates and readout architecture. Prototyping and beam test results with current generation MimoSTAR-2 sensors and a readout system featuring FPGA based on-the-fly hit finding and data sparsification are also presented

  9. Neutron star news and puzzles

    International Nuclear Information System (INIS)

    Prakash, Madappa

    2014-01-01

    Gerry Brown has had the most influence on my career in Physics, and my life after graduate studies. This article gives a brief account of some of the many ways in which Gerry shaped my research. Focus is placed on the significant strides on neutron star research made by the group at Stony Brook, which Gerry built from scratch. Selected puzzles about neutron stars that remain to be solved are noted

  10. Complexity and neutron star structure

    International Nuclear Information System (INIS)

    Chatzisavvas, K.Ch.; Psonis, V.P.; Panos, C.P.; Moustakidis, Ch.C.

    2009-01-01

    We apply the statistical measure of complexity introduced by Lopez-Ruiz, Mancini and Calbet (1995) to neutron star structure. We continue the recent application of Sanudo and Pacheco (2009) to white dwarfs. The interplay of gravity, the short-range nuclear force and the very short-range weak interaction shows that neutron stars, under the current theoretical framework, are ordered (low complexity) systems.

  11. Science, art, academia : Star Trek

    OpenAIRE

    Duca, Edward

    2016-01-01

    The Star Trek academic symposium will be held at the Faculty of ICT, University of Malta, on 15 and 16 July 2016. This event will be a platform for both academics from various disciplines as well as Star Trek fans to meet and explore the intersection between the humanities and the sciences. There will be inspirational presentations from national and international speakers, with the programme tailored to attract a wide audience. Contributors will be encouraged to explore contemporary issues in...

  12. Binary Neutron Star Mergers

    Directory of Open Access Journals (Sweden)

    Joshua A. Faber

    2012-07-01

    Full Text Available We review the current status of studies of the coalescence of binary neutron star systems. We begin with a discussion of the formation channels of merging binaries and we discuss the most recent theoretical predictions for merger rates. Next, we turn to the quasi-equilibrium formalisms that are used to study binaries prior to the merger phase and to generate initial data for fully dynamical simulations. The quasi-equilibrium approximation has played a key role in developing our understanding of the physics of binary coalescence and, in particular, of the orbital instability processes that can drive binaries to merger at the end of their lifetimes. We then turn to the numerical techniques used in dynamical simulations, including relativistic formalisms, (magneto-hydrodynamics, gravitational-wave extraction techniques, and nuclear microphysics treatments. This is followed by a summary of the simulations performed across the field to date, including the most recent results from both fully relativistic and microphysically detailed simulations. Finally, we discuss the likely directions for the field as we transition from the first to the second generation of gravitational-wave interferometers and while supercomputers reach the petascale frontier.

  13. AP1000 - update on projects in US and China

    Energy Technology Data Exchange (ETDEWEB)

    Godfrey, M. [Westinghouse Electric Company, Cranberry Township, Pennsy lvania (United States)

    2012-07-01

    Westinghouse is the only company solely focused on commercial nuclear technology. Westinghouse business is based on four product lines regionally divided: nuclear power plants, nuclear fuel, nuclear services and nuclear automation. The AP1000 is the technology of choice for more than half of the new plants identified in the US. Westinghouse has the only certified Generation III+ technology by the US Nuclear Regulatory Commission (NRC). The first Generation III+ plants are under construction in China and the US.

  14. AP1000 - update on projects in US and China

    International Nuclear Information System (INIS)

    Godfrey, M.

    2012-01-01

    Westinghouse is the only company solely focused on commercial nuclear technology. Westinghouse business is based on four product lines regionally divided: nuclear power plants, nuclear fuel, nuclear services and nuclear automation. The AP1000 is the technology of choice for more than half of the new plants identified in the US. Westinghouse has the only certified Generation III+ technology by the US Nuclear Regulatory Commission (NRC). The first Generation III+ plants are under construction in China and the US.

  15. 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.

  16. Coupled-bunch instabilities in the APS ring

    International Nuclear Information System (INIS)

    Emery, L.

    1991-01-01

    A study of coupled bunch instabilities for the APS storage ring is presented. The instabilities are driven by the higher-order modes of the fifteen 352-MHz single-cell RF cavities. These modes are modeled using the 2-D cavity program URMEL. The program ZAP is then used to estimate the growth time of the instabilities for an equally-spaced bunch pattern. The cavity modes most responsible for the instabilities will be singles out for damping. 7 refs., 5 tabs

  17. Hydrothermal waves in evaporating sessile drops (APS 2009)

    OpenAIRE

    Brutin, D.; Rigollet, F.; LeNiliot, C.

    2009-01-01

    This fluid dynamics video was submitted to the Gallery of Fluid Motion for the 2009 APS Division of Fluid Dynamics Meeting in Minneapolis, Minnesota. Drop evaporation is a simple phenomena but still unclear concerning the mechanisms of evaporation. A common agreement of the scientific community based on experimental and numerical work evidences that most of the evaporation occurs at the triple line. However, the rate of evaporation is still empirically predicted due to the lack of knowledge o...

  18. Data Aggregation Gateway Framework for CoAP Group Communications

    OpenAIRE

    Minki Cha; Jung-Hyok Kwon; SungJin Kim; Taeshik Shon; Eui-Jik Kim

    2016-01-01

    In this paper, a data aggregation gateway framework (DA-GW) for constrained application protocol (CoAP) group communications is proposed. The DA-GW framework is designed to improve the throughput performance and energy efficiency of group communication to monitor and control multiple sensor devices collectively with a single user terminal. The DA-GW consists of four function blocks—the message analyzer, group manager, message scheduler and data handler—and three informative databases—the clie...

  19. [Traditional risk factors for cardiovascular disease in primary antiphospholipid syndrome (APS) when compared with secondary APS: a study with 96 patients].

    Science.gov (United States)

    Ribeiro, A R; Carvalho, J F

    2010-01-01

    To evaluate the prevalence of traditional risk factors in patients with primary antiphospholipid syndrome (APS) in comparison to those with systemic lupus erythematosus-secondary APS. Transversal study of 96 APS patients (Sapporo's criteria). Demographic and clinical data, cardiovascular risk factors and drug use were investigated. Thirty-nine Primary APS and 57 secondary APS were included. The groups did not differ regarding age (38.5 +/- 9.9 vs. 39.4 +/- 10.5 years, p=0.84) and female gender (84.6 vs. 96.5%, p=0.06), respectively. Arterial events were more observed in primary than secondary APS (59 vs. 36.8%, p=0.04) patients. No difference was seen concerning venous and obstetric events. In regard to traditional risk factors for cardiovascular disease, both groups were comparable related to current or previous smoking, sedentarism, family history for coronary disease, systemic hypertension, diabetes mellitus, overweight and obesity. The frequencies of altered lipid profiles were alike in the two groups, except for a higher prevalence of low HDL-c levels in primary APS group (84.6 vs. 45.5%, p=0.0001). Concerning drug use, no significant differences were observed related to chloroquine and statin use, however the secondary APS patients had a higher rate of prednisone use (10.2 vs. 57.9%, pAPS, except for a high frequency of low HDL-c in primary APS patients.

  20. Dust Around T Tauri Stars

    Directory of Open Access Journals (Sweden)

    Kyung-Won Suh

    2011-12-01

    Full Text Available To reproduce the multiple broad peaks and the fine spectral features in the spectral energy distributions (SEDs of T Tauri stars, we model dust around T Tauri stars using a radiative transfer model for multiple isothermal circumstellar dust shells. We calculate the radiative transfer model SEDs for multiple dust shells using the opacity functions for various dust grains at different temperatures. For six sample stars, we compare the model results with the observed SEDs including the Spitzer spectral data. We present model parameters for the best fit model SEDs that would be helpful to understand the overall structure of dust envelopes around classical T Tauri stars. We find that at least three separate dust components are required to reproduce the observed SEDs. For all the sample stars, an innermost hot (250-550 K dust component of amorphous (silicate and carbon and crystalline (corundum for all objects and forsterite for some objects grains is needed. Crystalline forsterite grains can reproduce many fine spectral features of the sample stars. We find that crystalline forsterite grains exist in cold regions (80-100 K as well as in hot inner shells.