Note: This page contains sample records for the topic star rs cnc from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

Spectroscopic and photometric observations of the short-period RS CVn-type star WY Cnc  

Microsoft Academic Search

High-resolution spectroscopic observations around the H\\\\alpha line and BVRI photometry of the eclipsing short-period RS CVn star WY Cnc are presented. The solutions of our radial velocity curves and light curves yielded the following values for masses and radii of the components: M1=0.84 M&sun;, M2=0.46 M&sun;, R1=1.06 R&sun;, R2= 0.65 R&sun;. The measured rotational broadenings of the spectral lines correspond

D. Kjurkchieva; D. Marchev; W. Ogloza

2004-01-01

2

RS CVn stars - Chromospheric phenomena  

NASA Astrophysics Data System (ADS)

The observational information regarding chromospheric emission features in surface-active RS CVn stars is reviewed. Three optical features are considered in detail: Ca II H and K, Balmer H-alpha and He I 10830 A. While the qualitative behavior of these lines is in accord with solar-analogy/rotation-activity ideas, the quantitative variation and scaling are very poorly understood. In many cases, the spectroscopic observations with sufficient SNR and resolution to decide these questions have simply not yet been made. The FK Com stars, in particular, present extreme examples of rotation that may well tax present understanding of surface activity to its limits.

Bopp, B. W.

3

Infrared photometry of the RS CVn short-period systems - XY UMa and WY Cnc  

SciTech Connect

Infrared J and K light curves of two RS CVn short-period systems, XY UMa and WY Cnc, are presented. Both systems show similar variability in the infrared to that observed in the visual. From the colors an infrared excess is inferred for the primary component of both systems. A new determination of their geometrical elements is presented and the resulting parameters are compared to those previously obtained from visible photometry. The light curves show peculiarities that may indicate the presence of gas streams in the systems. 27 refs.

Arevalo, M.J.; Lazaro, C. (Instituto de Astrofisica de Canarias, La Laguna (Spain))

1990-03-01

4

Seismology of Evolved Beta Scuti Stars and the Binary BQ CNC in the Praesepe Cluster  

NASA Astrophysics Data System (ADS)

Three d Scuti stars of Praesepe cluster (BT Cnc, KW 284 and EP Cnc) seem to be at the end of the hydrogen core burning in the subgiant phase. This is supported by the fitting of isochrones to the cluster and by the larger period of their pulsations compared to the other delta Scuti stars in the cluster. After the results obtained in a joint identification of the radial modes for four less evolved delta Scuti stars, we try to find a consistent identification of the modes in these three evolved stars. BQ Cnc is another delta Scuti star in Praesepe catalogued as a double-lined spectroscopic binary. Considering different assumptions about the real position of the isolated pulsating star in the HR diagram, we present the most plausible identification of their modes according to the results obtained for the other stars.

Hernandez, M. M.; Perez Hernandez, F.; Michel, E.; Belmonte, J. A.; Goupil, M. J.; Lebreton, Y.

5

Long-term starspot activity of short-period RS Canum Venaticorum stars. IV - WY CANCRI  

NASA Astrophysics Data System (ADS)

The photometric distortion waves in the short-period RS CVn system WY CnC are parametrized by a dark, circular spot model for the active regions on the primary star. From recent observations and archival sources, the changes in positions and areas of the active regions are inferred. For light curves with simultaneous visual and red or infrared data, the average temperatures of the spotted regions relative to the photosphere are evaluated. In 1989, it is found that T(spot) = 3970 + or - 300 K for a primary star temperature of 5520 K. Some indication is found of a nonuniform temperature distribution in longitude across the spotted area at this time. The active regions tend to occur at low latitudes, in contrast to the high latitudes previously found for SV Cam, RT And, and BH Vir. It is found again that the active regions fall into preferred longitudes near 90 and 270 deg.

Zeilik, M.; Cox, D. A.; Ledlow, M. J.; Rhodes, M.; Heckert, P. A.; Budding, E.

1990-11-01

6

Long-term starspot activity of short-period RS Canum Venaticorum stars. IV. WY Cancri  

SciTech Connect

The photometric distortion waves in the short-period RS CVn system WY CnC are parametrized by a dark, circular spot model for the active regions on the primary star. From recent observations and archival sources, the changes in positions and areas of the active regions are inferred. For light curves with simultaneous visual and red or infrared data, the average temperatures of the spotted regions relative to the photosphere are evaluated. In 1989, it is found that T(spot) = 3970 + or - 300 K for a primary star temperature of 5520 K. Some indication is found of a nonuniform temperature distribution in longitude across the spotted area at this time. The active regions tend to occur at low latitudes, in contrast to the high latitudes previously found for SV Cam, RT And, and BH Vir. It is found again that the active regions fall into preferred longitudes near 90 and 270 deg. 27 refs.

Zeilik, M.; Cox, D.A.; Ledlow, M.J.; Rhodes, M.; Heckert, P.A. (New Mexico Univ., Albuquerque (USA) U.S. Air Force Academy, Colorado Springs, CO (USA) Western Carolina Univ., Cullowhee, NC (USA))

1990-11-01

7

High resolution spectroscopy of RS CVn stars  

SciTech Connect

High resolution echelle-Reticon observations covering all orbital phases of the bright RS CVn stars sigma Gem and HR 5110 were obtained. Nine spectra with 0.16 A resolution show that the core of H..cap alpha.. in sigma Gem varies with orbital phase in agreement with the spot zones identified by Fried et al. (1983) and also that the H..cap alpha.. brightness of a zone changes in time. Neutral metal lines in the same echelle order have been studied to investigate the properties of the spots. A new method is described to determine spot areas and temperatures from temperature-sensitive metal lines. The lack of observed metal line variation in the normal spot zones requires a temperature difference between spot and photosphere greater than 1000/sup 0/K and spot area less than 20% of the disk. In an unusual event, a warmer short-lived spot appeared in the region between zones. Lines from the cool secondary of HR 5110 were detected on 16 spectra with resolution 0.3 A. New mass and light ratios (M/sub 2//M/sub 1/ = 0.54, F/sub 2//F/sub 1/ = 0.20) were determined. Effective temperatures of 6750/sup 0/K and 4700/sup 0/K for the primary and secondary, respectively, were estimated from the line spectrum.

Eker, Z.

1985-01-01

8

Long-term starspot activity of the eclipsing binaries BH Vir and WY Cnc  

Microsoft Academic Search

We present the results of multicolor photometry of the two spotted, short-period, late-type RS CVn stars BH Vir and WY Cnc.\\u000a We have derived the parameters of the binaries’ components, and refined their masses, radii, and luminosities. A strong flare\\u000a of WY Cnc was detected for the first time, and pre-flare variations of the star’s activity studied. Our observations and

A. V. Kozhevnikova; I. Yu. Alekseev; P. A. Heckert; V. P. Kozhevnikov

2007-01-01

9

Interpretation of unpolarized radio emission from RS CVn stars  

Microsoft Academic Search

The authors investigate the emission process and the energy budget of radio flares in RS CVn stars by applying various mechanisms to the close binary sigma2CrB (HD 146361) of RS CVn type. Radio emission from this system observed with the WSRT at 21 cm is explained as synchrotron emission from electrons with Lorentz factors 3.5-3.1 in magnetic fields of strength

J. Kuijpers; J. M. van der Hulst

1985-01-01

10

The non-synchronous systems among RS CVn stars  

Microsoft Academic Search

An RS CVn star is considered as nonsynchronous if its orbital period differs by more than 4 percent from its photometric period. Of 88 systems examined according to this criterion, 67 are synchronous, 21 are nonsynchronous. For the 21 nonsynchronous systems, it is found that their spectral types are most around KO-2 III and that their orbital eccentricities are larger

Hui-Song Tan; Xun-Hao Wang; Kai-Ke Pan

1991-01-01

11

Long-term starspot activity of the eclipsing binaries BH Vir and WY Cnc  

Microsoft Academic Search

We present the results of multicolor photometry of the two spotted, short-period, late-type RS CVn stars BH Vir and WY Cnc. We have derived the parameters of the binaries' components, and refined their masses, radii, and luminosities. A strong flare of WY Cnc was detected for the first time, and pre-flare variations of the star's activity studied. Our observations and

A. V. Kozhevnikova; I. Yu. Alekseev; P. A. Heckert; V. P. Kozhevnikov

2007-01-01

12

Starspot cycles of RS Canum Venaticorum type stars  

SciTech Connect

The starspot model was used to account for the photometric variations of RS Canum Venaticorum binaries. The twelve light curves of eight epochs for RS CVn, eleven light curves of six epochs for AR Lac and twelve light curves of nine epochs for V711 Tau were analyzed to investigate the cyclic variations of these systems. The spot parameters, as well as other elements of the systems, were determined for each epoch by adjusting the parameters to fit the light curves. To avoid subjective parameter adjustment, the Wilson and Devinney differential correction computer program was adopted and modified for the adjustments of the spot parameters. Models were tested using one or two circular spots on the secondary stars. The adjustable parameters are latitudes, longitudes, radii, and temperatures of the spots, the surface potentials, albedos, temperatures of the two stars and the orbital inclination. The light curve fitting was done by adjusting the spot parameters and other parameters until a good fit to the entire light curve was obtained. To find the starspot cycles, only the spot longitudinal variations were considered. For RS CVn, starspot cycles of 9.22 years and 9.00 years were determined for two spots. These cycles agree with the 9.4 year cycle of the distortion-wave found by Catalono et al.

Kang, Y.W.

1985-01-01

13

MOA-2010-BLG-523: "Failed Planet" = RS CVn Star  

NASA Astrophysics Data System (ADS)

The Galactic bulge source MOA-2010-BLG-523S exhibited short-term deviations from a standard microlensing light curve near the peak of an A max ~ 265 high-magnification microlensing event. The deviations originally seemed consistent with expectations for a planetary companion to the principal lens. We combine long-term photometric monitoring with a previously published high-resolution spectrum taken near peak to demonstrate that this is an RS CVn variable, so that planetary microlensing is not required to explain the light-curve deviations. This is the first spectroscopically confirmed RS CVn star discovered in the Galactic bulge. Based on observations made with the European Southern Observatory telescopes, Program ID 85.B-0399(I).

Gould, A.; Yee, J. C.; Bond, I. A.; Udalski, A.; Han, C.; Jørgensen, U. G.; Greenhill, J.; Tsapras, Y.; Pinsonneault, M. H.; Bensby, T.; Allen, W.; Almeida, L. A.; Bos, M.; Christie, G. W.; DePoy, D. L.; Dong, Subo; Gaudi, B. S.; Hung, L.-W.; Jablonski, F.; Lee, C.-U.; McCormick, J.; Moorhouse, D.; Muñoz, J. A.; Natusch, T.; Nola, M.; Pogge, R. W.; Skowron, J.; Thornley, G.; The ?FUN Collaboration; Abe, F.; Bennett, D. P.; Botzler, C. S.; Chote, P.; Freeman, M.; Fukui, A.; Furusawa, K.; Harris, P.; Itow, Y.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Miyake, N.; Ohnishi, K.; Rattenbury, N. J.; Saito, To.; Sullivan, D. J.; Sumi, T.; Suzuki, D.; Sweatman, W. L.; Tristram, P. J.; Wada, K.; Yock, P. C. M.; The MOA Collaboration; Szyma?ski, M. K.; Soszy?ski, I.; Kubiak, M.; Poleski, R.; Ulaczyk, K.; Pietrzy?ski, G.; Wyrzykowski, ?.; The OGLE Collaboration; Alsubai, K. A.; Bozza, V.; Browne, P.; Burgdorf, M. J.; Calchi Novati, S.; Dodds, P.; Dominik, M.; Finet, F.; Gerner, T.; Hardis, S.; Harpsøe, K.; Hessman, F. V.; Hinse, T. C.; Hundertmark, M.; Kains, N.; Kerins, E.; Liebig, C.; Mancini, L.; Mathiasen, M.; Penny, M. T.; Proft, S.; Rahvar, S.; Ricci, D.; Sahu, K. C.; Scarpetta, G.; Schäfer, S.; Schönebeck, F.; Snodgrass, C.; Southworth, J.; Surdej, J.; Wambsganss, J.; MiNDSTEp Consortium, The; Street, R. A.; Horne, K.; Bramich, D. M.; Steele, I. A.; The RoboNet Collaboration; Albrow, M. D.; Bachelet, E.; Batista, V.; Beatty, T. G.; Beaulieu, J.-P.; Bennett, C. S.; Bowens-Rubin, R.; Brillant, S.; Caldwell, J. A. R.; Cassan, A.; Cole, A. A.; Corrales, E.; Coutures, C.; Dieters, S.; Dominis Prester, D.; Donatowicz, J.; Fouqué, P.; Henderson, C. B.; Kubas, D.; Marquette, J.-B.; Martin, R.; Menzies, J. W.; Shappee, B.; Williams, A.; van Saders, J.; Zub, M.; The PLANET Collaboration

2013-02-01

14

A study of active regions on RS CVn stars  

SciTech Connect

Intense observational scrutiny was combined with theoretical modeling efforts for three regular RS CVn stellar systems, II Peg, UX Ari, and HR 1099. Observational analysis consisted of application of the technique of spectral subtraction to yield excess emission profiles for these stars; these profiles were considered indicative of extraphotospheric activity. The subtraction technique was applied to the H alpha, H beta, Ca II H, Ca II K, and Ca II infrared triplet lines, and the resulting fluxes were examined for correlations with phase and with each other. An analysis of the velocity information present in the line profiles was also attempted. Theoretical work consisted of the application of radiative transfer models to stellar plage and prominence models in an attempt to determine the physical nature of the active regions on these stars. The radiative transfer models were also used to test the limits of validity of the spectral subtraction technique itself.

Buzasi, D.L.

1989-01-01

15

Doppler Imaging of spotted stars - Application to the RS Canum Venaticorum star HR 1099  

NASA Astrophysics Data System (ADS)

A technique for imaging the surfaces of certain rapidly rotating spotted stars is discussed. The method exploits the correspondence between wavelength position across a rotationally broadened spectral line and spatial position across the stellar disk. Preliminary Doppler Images of the RS CVn star HR 1099 show spots which exhibit a striking similarity in shape and location to X ray images of solar coronal holes. It is suggested that the large star spots on RS CVn's and other active late-type stars emerge at low latitude as scaled-up analogs of solar complexes, but as they migrate poleward, they more closely resemble photospheric analogs of solar coronal holes. The evolution of starspots appears remarkably similar to that of large-scale magnetic fields of the sun.

Vogt, S. S.; Penrod, G. D.

1983-09-01

16

Quiescent and Flaring Structure in RS Canum Venaticorum Stars  

NASA Astrophysics Data System (ADS)

Four of the most active RS CVn stars (V711 Tau, II Peg, ? Gem, and UX Ari) have been observed for a total of 3 Ms with the Extreme Ultraviolet Explorer satellite (EUVE) between 1992 and 2000 January. Flaring and quiescent states of extreme ultraviolet spectra (??70-740) and light curves (??75-175) have been analyzed to provide emission measure distributions (EMD) for these systems in the range logTe(K)~5.6-7.4, based principally on iron lines. Flux measurements obtained with IUE and the Orbiting and Retrievable Far and Extreme Ultraviolet Spectrometer (ORFEUS) complete the EMD in the lower temperature range [logTe(K)~4.0-5.6]. Frequent flaring activity has been found in the systems, including an increase during the rise phase by a factor of ~9 in the flux of ? Gem, the largest flare enhancement observed with EUVE. Analyses of the EUVE emission in the active single star AB Dor and the low-rotation giant star ? Cet are also included. The EMDs are remarkably similar among all the stars, showing a narrow enhancement or ``bump'' around logTe(K)~6.9. These narrow bumps are apparently unrelated to rotation rate, spectral type, binarity, or evolutionary stage. Significant material is found at logTe(K)>~7.0 for the most active stars. Modulation of the EUV flux outside of flaring occurs in four of the stars (? Gem, V711 Tau, UX Ari, AB Dor). The electron density ranges between Ne~1012 and ~1013 cm-3, measured at logTe(K)~7.0, and may reach higher values during flares. These densities and EMD values imply small scale sizes for emitting regions.

Sanz-Forcada, J.; Brickhouse, N. S.; Dupree, A. K.

2002-05-01

17

Radio outbursts in RS Canum Venaticorum stars - coronal heating and electron runaway  

SciTech Connect

Radio outbursts of RS CVn stars are sometimes thought of as analogs of flares in red dwarf stars. The possibility is examined that the outbursts are not due to flares, but rather to a highly efficient case of coronal heating: mechanical energy reaching the corona from the convection zone of an RS CVn star gives rise to induced electric fields which may be so large that electron runaway becomes possible. It is proposed that gyrosynchrotron emission from fast electrons which are produced by this process are the source of radio outbursts from RS CVn stars. 31 references.

Mullan, D.J.

1985-08-01

18

Long-term chromospheric activity of non-eclipsing RS CVn-type stars  

Microsoft Academic Search

Context. The IUE database provides a large number of UV high and\\u000alow-resolution spectra of RS CVn-type stars from 1978 to 1996. In particular,\\u000amany of these stars were monitored continuously during several seasons by IUE.\\u000aAims. Our main purpose is to study the short and long-term chromospheric\\u000aactivity of the RS CVn systems most observed by IUE: HD 22468

Andrea P. Buccino; Pablo J. D. Mauas

2008-01-01

19

Long-term chromospheric activity of non-eclipsing RS CVn-type stars  

Microsoft Academic Search

Context: The IUE database provides several UV high and low-resolution spectra of RS CVn-type stars from 1978 to 1996. In particular, many of these stars were monitored continuously during several seasons by IUE. Aims: Our main purpose is to study the short and long-term chromospheric activity of the RS CVn systems most observed by IUE: HD 22 468 (V711 Tau,

A. P. Buccino; P. J. D. Mauas

2009-01-01

20

Optical Flaring on Rs-Canum Stars - the Case of II-Pegasi in 1992SEP  

NASA Astrophysics Data System (ADS)

Recent observational results by Mathioudakis et al. have suggested that optical Uband flares are a frequent occurrence on the RS CVn star, II Peg. We present U-band monitoring of II Peg in 1992 September which failed to show any evidence of flaring to very low limits. We show that these data are inconsistent with the flaring rates reported earlier and suggest that either II Peg was in a state of low flare activity in 1992, or that it was unusually active at the time of Mathioudakis et al.'s observations. Key words: stars: activity - binaries: close - stars: flare - stars: individual: II Peg - stars: late-type.

Byrne, P. B.; Lanzafame, A. C.; Sarro, L. M.; Ryans, R.

1994-09-01

21

Spectroscopic and photometric observations of the short-period RS CVn-type star CG Cyg  

Microsoft Academic Search

Spectroscopic observations around the Halpha line and BVR photometry of the eclipsing short-period RS CVn-star CG Cyg are presented. The solutions of the radial velocity curves and the light curves yielded the following masses and radii of the star components: M1=0.97 Msun, M2=0.80 Msun, R1=1.00 Rsun, R2=0.83 Rsun. The measured rotational broadenings of the observed lines correspond to equatorial velocities

D. P. Kjurkchieva; D. V. Marchev; W. Ogloza

2003-01-01

22

Spectroscopic observations of the short-period, RS CVn-type star SV Cam  

Microsoft Academic Search

Spectroscopic observations of the eclipsing, short-period RS CVn-star SV Cam in the range 6500-6700 Å, covering the whole orbital period are presented. The absorption profiles of the lines Halpha and FeI 6678 are doubled out of the eclipses. The relative contribution of the secondary star is stronger in the FeI 6678 line than in Halpha . We determined K1=123.1+\\/-1.2 km

D. P. Kjurkchieva; D. V. Marchev; S. Zola

2002-01-01

23

Radial velocity study of four southern RS CVn candidates and related field stars  

SciTech Connect

Radial velocity variations are demonstrated for four southern RS CVn candidates: HD 39937, 101379, 155555, and 174429. The period of HD 155555 appears to have decreased by about one part in 100 000 over the past 18 yr. In addition, high-resolution observations of the Ca II H and K profiles and the Mg II 2800-A emission doublet are presented. These enhance the likelihood of these being RS CVn objects. Radial velocity data for 15 other late-type bright field stars are presented. Some of these were observed by Copernicus and may exhibit unusual chromospheres, while the rest lack radial velocity information as tabulated in the Bright Star Catalog. All velocity measures have been corrected to the IAU heliocentric system.

Stacy, J.G.; Stencel, R.E.; Weiler, E.J.

1980-07-01

24

Spectroscopic and photometric observations of the short-period RS CVn star RT And  

Microsoft Academic Search

Spectroscopic observations in the range 6500-6700 Å and BVRI photometry of the eclipsing short-period RS CVn-star RT And are presented. We determined K1=130 km s-1 and K2=175.8 km s-1 by measurement of the double profiles of the lines Halpha and FeI 6678, and obtained the mass ratio q=0.74 and masses of the star components M1=1.23 Msun and M2=0.91 Msun. It

D. P. Kjurkchieva; D. V. Marchev; W. Ogloza

2001-01-01

25

Chemical Composition of the RS CVn-type Star Lambda Andromedae  

Microsoft Academic Search

Photospheric parameters and chemical composition are determined for the single-lined chromospherically active RS CVn-type star lambda And (HD 222107). From the high resolution spectra obtained on the Nordic Optical Telescope, abundances of 22 chemical elements and isotopes, including such key elements as 12C, 13C, N and O, were investigated. The differential line analysis with the MARCS model atmospheres gives T

G. Tautvaiÿsienúe; G. Barisevicius; S. Berdyugina; Y. Chorniy; I. Ilyin

2010-01-01

26

Spectral decomposition and multiple periodicities in the photometric light curves of RS CVn stars  

SciTech Connect

A search is made for multiple-periodic structure in a major subset of the RS CVn class of chromospherically active, binary-star systems using a rigorous numerical approach appropriate to unevenly spaced, gapped data. The goal is to characterize properly the spectral content of RS CVn binary light curves and evaluate how this information can constrain current models for the system. Thirty-six RC CVn systems were observed down to a statistical noise level of about 0.01 m. Most of the systems exhibit multiple periodic structure; 14 show changes in the photometric period on a timescale of a few hundred days. A preference is found for photometric periods with timescales near the orbital and half-orbital periods. The effect is particularly strong for the shorter period systems and is interpreted as evidence for synchronous, or near-synchronous, rotation. 9 refs.

Nelson, E.R.; Zeilik, M. (Science Applications International Corp., Albuquerque, NM (USA) New Mexico Univ., Albuquerque (USA))

1990-01-01

27

Long-term starspot activity of short-period RS Canum Venaticorum stars. III - BH Virginis  

SciTech Connect

The photometric distortion waves in the light curves of the short-period RS CVn system BH Vir by a dark, circular spot model for the active regions on the primary star is parameterized. Recent observations and archival sources are used to infer the positions and areas of the active regions. For light curves with simultaneous B and R or V and I data, the temperatures of the spotted regions relative to the photospheres can be evaluated. For BH Vir in 1986, T(spot) = 4900 + or - 500 K. The active regions tend to occur at high latitudes and at preferred longitudes near 90 and 270 deg. 32 refs.

Zeilik, M.; Ledlow, M.; Rhodes, M.; Arevalo, M.J.; Budding, E. (New Mexico Univ., Albuquerque (USA) Air Force Academy, Colorado Springs, CO (USA) Instituto de Astrofisica de Canarias, La Laguna (Spain) Carter Observatory, Wellington (New Zealand))

1990-05-01

28

The Pulsational Behavior of the High Amplitude d Scuti Star RS Gruis  

NASA Astrophysics Data System (ADS)

RS Gruis is a high-amplitude delta Scuti-type variable star with a mean amplitude of almost half a magnitude in V and a period of almost 3.5 hours. The most recent study of this star by Derekas et al. (2009) suggests the presence of a low-mass dwarf star companion close to the variable star with a period of 11.5 days. Rodriguez et al. (1995) have also shown a decreasing rate of the period of dP/Pdt = -10.6 • 10-8 / y. Using an extended dataset comprising BVIc CCD observations acquired at the Astronomical Observatory of the Instituto Copérnico, data from ASAS and HIPPARCOS, and the existing CCD observations in the AAVSO International Database, we have performed an extensive periodgram and times of maximum analysis looking for long term variations. As a preliminary result, we confirmed that the period varies, but, since 1995, instead of decreasing, it has increased. We also found a small peak in the power spectrum in good agreement with the period suggested for the binary companion.

García, J.

2012-06-01

29

Long-term starspot activity of short-period RS Canum Venaticorum stars. II. RT Andromedae  

SciTech Connect

The photometric distortion waves in the light curves of the short-period RS CVn system RT And are parameterized by means of a dark, circular starspot model. The light curves are drawn from archival sources and 1987 and 1989 observations. The longitudes, latitudes, and areas of the active regions are inferred and the information content of the archival data is evaluated. It is concluded that one large starspot region on the primary star at high latitude and near quadrature longitudes can account for the major maculation effects since 1920. The temperature difference between the spotted region and the photosphere is 1100 to 1200 K. Good quality light curves result in an eccentricity (e = 0.026) and major axis orientation consistent with those reported by others using different procedures. 36 refs.

Zeilik, M.; Cox, D.A.; De Blasi, C.; Rhodes, M.; Budding, E. (New Mexico Univ., Albuquerque (USA) Carter Observatory, Wellington (New Zealand))

1989-10-01

30

Doppler Imagery of the Spotted RS Canum Venaticorum Star HR 1099 (V711 Tauri) from 1981 to 1992  

Microsoft Academic Search

We present a set of 23 Doppler images of the spotted RS CVn star HR 1099 (V711 Tauri; HD 22468) obtained from 1981 to 1992. HR 1099 shows a large, cool polar spot that has persisted for the 11 yr of this study and other low-latitude spots that come and go on relatively short (less than 1 yr) timescales and

Steven S. Vogt; Artie P. Hatzes; Anthony A. Misch; M. Kürster

1999-01-01

31

The chromosphere of II Pegasi: multi-line modelling of an RS Canum Venaticorum star  

NASA Astrophysics Data System (ADS)

We present the first simultaneous multi-line fitting of a semi-empirical atmospheric model with a chromosphere and transition region to the H I and Ca II spectra of an RS CVn star (II Peg). The static component of the H? emission core, the line profile of H? , the apparent absence of H? and Hdelta , and the emission core profiles of Ca II K and two of the Ca II IR(3) lines are all approximately fitted by a static 1D model with the following properties: log m at the onset of the transition region is ~ -2.85, and a 6000 K plateau in the upper chromosphere that spans about a decade in log m. In particular, the model is able to reproduce the unusually steep Balmer decrement (compared to the dMe stars), in which H? is strongly in emission and H? is in absorption, without recourse to extra-atmospheric material. The Ca II IR(3) lines are best fit by a model in which T_min is cooler by 300 K and shallower by over half a decade in log m than that which best fits the optical lines. The emergent flux in the IR(3) line cores arises from the T_min region, whereas the other diagnostics arise from layers well above T_min, and it is postulated that this may be the cause of the discrepancy. There has very recently been evidence from other investigators that the metallicity of II Peg may be sub-solar, and we find that models with [{A/ H}]=-0.4 provide a somewhat better fit to all the lines considered.

Short, C. I.; Byrne, P. B.; Panagi, P. M.

1998-10-01

32

CNC Router Fundamentals Orientation  

NSDL National Science Digital Library

These zipped documents from MatEd provide information on designing a course on CNC Router Fundamentals Orientation. At the end of the course, students will be able to identify manufactured projects or products that are compatible for production on CNC routers, operate a Techno brand CNC router, and have proposed a project to reinforce these concepts. The documents include a draft syllabus, contact information for the author of the course, a sample new course proposal form, and a course outline.

Kraft, Patrick

2012-10-23

33

On the coronae of rapidly rotating stars. I - The relation between rotation and coronal activity in RS CVn systems  

Microsoft Academic Search

Soft X-ray observations are presented of a nearly complete sample of RS Canum Venaticorum systems taken with the Einstein X-ray Observatory. It is shown that the quiescent coronal activity, as measured by the ratio of the X-ray to bolometric flux, is directly proportional to the angular velocity of the star with the active chromosphere in these systems. This relation is

F. M. Walter; S. Bowyer

1981-01-01

34

CNC Programming I.  

ERIC Educational Resources Information Center

This document contains five units for a course in computer numerical control (CNC) for computer-aided manufacturing. It is intended to familiarize students with the principles and techniques necessary to create proper CNC programs manually. Each unit consists of an introduction, instructional objectives, learning materials, learning activities,…

Casey, Joe

35

Carney complex (CNC)  

PubMed Central

The Carney complex (CNC) is a dominantly inherited syndrome characterized by spotty skin pigmentation, endocrine overactivity and myxomas. Skin pigmentation anomalies include lentigines and blue naevi. The most common endocrine gland manifestations are acromegaly, thyroid and testicular tumors, and adrenocorticotropic hormone (ACTH)-independent Cushing's syndrome due to primary pigmented nodular adrenocortical disease (PPNAD). PPNAD, a rare cause of Cushing's syndrome, is due to primary bilateral adrenal defect that can be also observed in some patients without other CNC manifestations or familial history of the disease. Myxomas can be observed in the heart, skin and breast. Cardiac myxomas can develop in any cardiac chamber and may be multiple. One of the putative CNC genes located on 17q22-24, (PRKAR1A), has been identified to encode the regulatory subunit (R1A) of protein kinase A. Heterozygous inactivating mutations of PRKAR1A were reported initially in 45 to 65 % of CNC index cases, and may be present in about 80 % of the CNC families presenting mainly with Cushing's syndrome. PRKAR1A is a key component of the cAMP signaling pathway that has been implicated in endocrine tumorigenesis and could, at least partly, function as a tumor suppressor gene. Genetic analysis should be proposed to all CNC index cases. Patients with CNC or with a genetic predisposition to CNC should have regular screening for manifestations of the disease. Clinical work-up for all the manifestations of CNC should be performed at least once a year in all patients and should start in infancy. Cardiac myxomas require surgical removal. Treatment of the other manifestations of CNC should be discussed and may include follow-up, surgery, or medical treatment depending on the location of the tumor, its size, the existence of clinical signs of tumor mass or hormonal excess, and the suspicion of malignancy. Bilateral adrenalectomy is the most common treatment for Cushing's syndrome due to PPNAD.

Bertherat, Jerome

2006-01-01

36

Radio-wavelength observations of magnetic fields on active dwarf-M, RS CVN and magnetic stars  

SciTech Connect

The dwarf M stars YZ Canis Minoris and AD Leonis exhibit narrow band, slowly varying (hours) microwave emission that cannot be explained by conventional thermal radiation mechanisms. The dwarf M stars AD Leonis and Wolf 424 emit rapid spikes whose high brightness temperatures similarly require a nonthermal radiation process which could result from coherent mechanisms such as an electron-cyclotron maser or coherent-plasma radiation. If the electron-cyclotron maser emits at the second or third harmonic of the gyrofrequency, the coronal magnetic field strength H = 250 or 167 G and constraints on the plasma frequency imply an electron density of 6 x 10/sup 9//cm/sup 3/. Coherent-plasma radiation requires similar values of electron density but much weaker magnetic fields. Radio spikes from AD Leonis and Wolf 424 have rise times tau/sub R/ < 5 ms, indicating a linear size of L < 1.5 x 10/sup 8/ cm, or less than 0.005 of the stellar radius. Although Ap magnetic stars have strong dipole magnetic fields, they exhibit no detectable gyroresonant radiation, suggesting that these stars do not have hot, dense coronae. The binary RS CVn star UX Arietis exhibits variable emission at 6 cm wavelength on time scales ranging from 30 s to more than one hour. The shortest variation implies a linear size much less than that of the halo observed by VLBI techniques, and most probably sizes smaller than those of the component stars. The observed variations might be due to absorption by a thermal plasma located between the stars.

Lang, K.R.

1986-01-01

37

CAD/CAM/CNC.  

ERIC Educational Resources Information Center

Includes "Quick Start CNC (computer numerical control) with a Vacuum Filter and Laminated Plastic" (Domermuth); "School and Industry Cooperate for Mutual Benefit" (Buckler); and "CAD (computer-assisted drafting) Careers--What Professionals Have to Say" (Skinner). (JOW)

Domermuth, Dave; And Others

1996-01-01

38

INVESTIGATION FOR THE ENRICHMENT PATTERN OF THE ELEMENT ABUNDANCES IN r+s STAR HE 0338 - 3945: A SPECIAL r-II STAR?  

SciTech Connect

The very metal-poor star HE 0338 - 3945 shows a double-enhanced pattern of the neutron-capture elements. The study of this sample could help people gain a better understanding of s- and r-process nucleosynthesis at low metallicity. Using a parametric model, we find that the abundance pattern of the neutron-capture elements could be best explained by a binary system formed in a molecular cloud that had been polluted by r-process material. The observed abundance pattern of C and N can be explained by an asymptotic giant branch (AGB) model. Combined with the parameters obtained from Cui and Zhang, we suggest that the initial mass of the AGB companion is most likely to be about 2.5 M{sub sun}, which excludes the possibility of forming a Type 1.5 supernova. By comparing with the observational abundance pattern of CS 22892 - 052, we find that the dominant production of O should accompany the production of the heavy r-process elements of r+s stars. Similar to r-II stars, the heavy r-process elements are not produced in conjunction with all the light elements from the Na to Fe group. The abundance pattern of the light and r-process elements for HE 0338 - 3945 is very close to the pattern of the r-II star CS 22892 - 052. Therefore, we suggest that HE 0338 - 3945 should be a special r-II star.

Cui Wenyuan; Zhang Jiang; Zhu Zizhong; Zhang Bo, E-mail: wenyuancui@126.co, E-mail: zhangbo@hebtu.edu.c [Department of Physics, Hebei Normal University, 113 Yuhua Dong Road, Shijiazhuang 050016 (China)

2010-01-01

39

X-ray-selected candidates for the RS CVn and W UMa classes of binary stars  

SciTech Connect

X-ray luminosity, spectral type, radial-velocity variation, rotationally broadened line profile, and Ca II H and K line emission data are used to identify 12 new candidates for the RS CVn class and seven new candidates for the W UMa class from spectroscopic binaries which are contained in the Einstein Extended Medium Sensitivity Survey. Under the assumption that the candidates are genuine members of each class, local space density estimates of 4.47 + or - 1.19 x 10 to the -4th/cu pc for RS CVn binaries and 8.47 + or - 3.00 x 10 to the -5th/cu pc for W UMa binaries are found. Although the density estimate for the W UMa binaries is shown to be consistent with previous estimates obtained from optically selected samples, the estimate for the RS CVn binaries is more than an order of magnitude greater than previously determined space densities. 40 refs.

Fleming, T.A.; Gioia, I.M.; Maccacaro, T. (Joint Institute for Laboratory Astrophysics, Boulder, CO (USA); Max-Planck-Institut fuer extraterrestrische Physik, Garching (Germany, F.R.); Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (USA))

1989-08-01

40

X-ray-selected candidates for the RS CVn and W UMa classes of binary stars  

Microsoft Academic Search

X-ray luminosity, spectral type, radial-velocity variation, rotationally broadened line profile, and Ca II H and K line emission data are used to identify 12 new candidates for the RS CVn class and seven new candidates for the W UMa class from spectroscopic binaries which are contained in the Einstein Extended Medium Sensitivity Survey. Under the assumption that the candidates are

Thomas A. Fleming; Isabella M. Gioia; Tommaso Maccacaro; MA Cambridge

1989-01-01

41

The Hamburg/ESO R-process Enhanced Star survey (HERES). VIII. The r+s star HE 1405-0822  

NASA Astrophysics Data System (ADS)

Aims: The aim of this study is a detailed abundance analysis of the newly discovered r-rich star HE 1405-0822, which has [Fe/H] = -2.40. This star shows enhancements of both r- and s-elements, [Ba/Fe] = + 1.95 and [Eu/Fe] = 1.54, for which reason it is called r+s star. Methods: Stellar parameters and element abundances were determined by analyzing high-quality VLT/UVES spectra. We used Fe I line excitation equilibria to derive the effective temperature. The surface gravity was calculated from the Fe i/Fe ii and Ti i/Ti ii equilibria. Results: We determined accurate abundances for 39 elements, including 19 neutron-capture elements. HE 1405-0822 is a red giant. Its strong enhancements of C, N, and s-elements are the consequence of enrichment by a former AGB companion with an initial mass of less than 3 M?. The heavy n-capture element abundances (including Eu, Yb, and Hf) seen in HE 1405-0822 do not agree with the r-process pattern seen in strongly r-process-enhanced stars. We discuss possible enrichment scenarios for this star. The enhanced ? elements can be explained as the result of enrichment by supernovae of type II. Na and Mg may have partly been synthesized in a former AGB companion, when the primary 22Ne acted as a neutron poison in the 13C-pocket. Based on observations collected at the European Southern Observatory, Paranal, Chile (Proposal numbers 170.D-0010G, and 170.D-0010J).Tables 5, 6 are available in electronic form at http://www.aanda.org

Cui, W. Y.; Sivarani, T.; Christlieb, N.

2013-10-01

42

The Distribution of Activity on the RS CVn–Type Star SZ Piscium  

Microsoft Academic Search

We use contemporaneous spectra and BV light curves to derive a model of the distribution of spots and active regions on the cooler component of SZ Psc for the 1993-1994 season. For that epoch, both spots and active regions were visible at all rotational phases of this chromospherically active star. The lack of large distortions of Doppler profiles of optical

2007-01-01

43

ISOPHOT Observations of the RS CVn-type Star II Peg  

NASA Astrophysics Data System (ADS)

The RS CVn-type system II Pegasi was observed by ISOPHOT on ISO to derive spectrophotometric data in the 2.5 - 12 micron range, and multifilter photometry between 3.6 and 200 microns. Contemporary to ISO observations we also secured: - millimeter data with the IRAM interferometer; - near infrared and optical photometry with the 91 cm and the 80 cm APT, respectively, at Catania Observatory. Preliminary data on the spectral distribution in the full 2.5 - 200 micron range indicate the presence of a remarkably well defined IR excess whose nature is under investigation.

Rodono, M.; Pagano, I.; Cutispoto, G.; Marino, G.; Messina, S.; Leto, G.; Trigilio, C.; Umana, G.; Neri, R.

44

Difference at chromospheric levels between rs cvn-type binaries, active and quiet chromosphere single stars, and active and quiet regions in the sun  

SciTech Connect

This paper summarizes the differences in the properties of active chromospheres compared with quiet chromospheres by comparing active and quiet regions on the Sun, active and quiet chromosphere stars, and the very active chromospheres seen in close binary systems with chromospheres of single stars. In particular, the chromospheres of the RS CVn-type binary systems UX Arietis and HR 1099 and the chromosphere of UX Arietis during a flare are modeled.

Linsky, J.L.

1980-01-01

45

AM Cnc, AN Leo und HO Leo - drei vernachlaessigte RR-Lyrae-Sterne  

NASA Astrophysics Data System (ADS)

Based on CCD observations, new ephemerides and lightcurves of the long time neglecte RR Lyrae stars AM Cnc, AN Leo and HO Leo are presented. AM Cnc and HO Leo seemed to present a Blazhko effect, for night to night variations in the shape of the lightcurves and maxima timings have been registered.

Groebel, Rainer

2012-03-01

46

Correlation effects in microwave observations of selected RS CVn-like stars  

Microsoft Academic Search

Sets of dual frequency microwave data on selected chromospherically active stars, from the Australia Telescope Compact Array, have been investigated for their auto and cross-correlation effects. Comparison of cross-correlation peak values with theoretical expectation indicates a high degree of real physical connection between the emission at the pairs of frequencies (4.8 and 8.64 GHz) compared. This fact should help constrain

E. Budding; J. Lim; O. B. Slee; S. M. White

2002-01-01

47

MAXI/GSC detection of an active state of the RS CVn type star UX Ari  

NASA Astrophysics Data System (ADS)

We report an X-ray detection with MAXI/GSC from the position consistent with the RS CVn type variable UX Ari. The flux increasing was observed from 2011-04-26 09:36 (UT) (= MJD 55677.414) and the active state lasted at least to the latest transit starting at 2011-04-27 05:42 (UT) (= MJD 55678.238). The active state seems to comprise multiple flares, and the flux maximum was observed at the transit starting from 2011-04-27 01:13 (UT) (= MJD 55678.051) with the preliminary flux of about 130 +-30 mCrab (1-sigma statistical error) in the 4-10 keV band.

Matsumura, T.; Tsuboi, Y.; Yamazaki, K.; Morii, M.; Ueno, S.; Tomida, H.; Kohama, M.; Ishikawa, M.; Mihara, T.; Sugizaki, M.; Serino, M.; Nakahira, S.; Yamamoto, T.; Sootome, T.; Matsuoka, M.; Kawai, N.; Sugimori, K.; Usui, R.; Toizumi, T.; Yoshida, A.; Yamaoka, K.; Tsunemi, H.; Kimura, M.; Kitayama, H.; Negoro, H.; Nakajima, M.; Suwa, F.; Ueda, Y.; Hiroi, K.; Shidatsu, M.

2011-04-01

48

MAXI/GSC detection of a possible flare from the RS CVn type star SZ Psc  

NASA Astrophysics Data System (ADS)

MAXI/GSC detected an increased X-ray emission from the position consistent with the RS CVn type variable, SZ Psc. The significant X-ray flux in the 2-10 keV band had been detected since 2011-11-05 18:20 (UT) (= MJD 55870.764) and the activity continued at least until 2011-11-05 23:03 (UT) (= MJD 55870.960). The maximum flux of about 110 mCrab was observed during a GSC scan transit starting at 2011-11-05 19:53 (UT) (= MJD 55870.828) and the X-ray luminosity is about 3×1033 ergs/s (distance is assumed to 88 pc).

Negoro, H.; Usui, R.; Yamazaki, K.; Tsuboi, Y.; Matsumura, T.; Matsuoka, M.; Sugizaki, M.; Mihara, T.; Serino, M.; Nakahira, S.; Yamamoto, T.; Sootome, T.; Ueno, S.; Tomida, H.; Kohama, M.; Ishikawa, M.; Kawai, N.; Morii, M.; Sugimori, K.; Toizumi, T.; Yoshida, A.; Yamaoka, K.; Tsunemi, H.; Kimura, M.; Kitayama, H.; Nakajima, M.; Suwa, F.; Ueda, Y.; Hiroi, K.; Shidatsu, M.

2011-11-01

49

Chemical Composition of the RS CVn-type Star 33 Piscium  

NASA Astrophysics Data System (ADS)

Abundances of 22 chemical elements, including the key elements and isotopes such as 12C, 13C, N and O, are investigated in the spectrum of 33 Psc, a single-lined RS CVn-type binary of low magnetic activity. The high resolution spectra were observed on the Nordic Optical Telescope and analyzed with the MARCS model atmospheres. The following main parameters have been determined: T eff = 4750 K, log g = 2.8, [Fe/H] = -0.09, [C/Fe] = -0.04, [N/Fe] = 0.23, [O/Fe] = 0.05, C/N = 2.14, 12C/13C = 30, which show the first-dredge-up mixing signatures and no extra-mixing.

Barisevi?ius, G.; Tautvaišien?, G.; Berdyugina, S.; Chorniy, Y.; Ilyin, I.

50

Rotational Brightness Modulation and Starspots on the RS CVn-type Stars IN Com, IL Com, UX Ari, and V711 Tau  

Microsoft Academic Search

UBVRI photometric observations and models of spotting are presented for four noneclipsing RS CVn systems: IN Com (G5III\\/IV), IL Com (F8V+F8V), UX Ari (K01V+G5V), and V711 Tau (K1IV+G5V). A low amplitude variability caused by cold (?T=1700K)spots which can occupy up to 19% of the star's surface is confirmed for the little-studied star IL Com. Long-term light curves are constructed and

I. Yu. Alekseev; A. V. Kozhevnikova

2004-01-01

51

Two New EW-type Eclipsing Variables Near AK Cnc  

NASA Astrophysics Data System (ADS)

Two new eclipsing variable stars, USNO-B1.0 1015-0165372 = 2MASS 08543896+1133002 and USNO-B1.0 1017-0168554 = 2MASS 08534894+1143534, were discovered in the field of the cataclysmic variable star AK Cnc. The remotely controlled astrophysical refractor AP-180 of the Tzec Maun Observatory (USA) has been used. Both binary systems were classified as EW-type. All parameters needed for the General Catalog of Variable Stars with corresponding errors were determined for both stars. We have registered these stars in VSX (Variable Stars Index, AAVSO) and these stars have got names VSX J085438.9+113300 and VSX J085348.9+114353, respectively.

Virnina, Natalia A.

2011-01-01

52

MAXI/GSC detection of a possible X-ray flare from an RS CVn star GT Mus (=4U1137-65, HD 101379)  

NASA Astrophysics Data System (ADS)

On 2010-11-10 06:17:27 UT (= MJD 55510.26211), the MAXI/GSC transient alert system triggered on enhanced X-ray emission from the position: (R.A., Dec) = (174.925, 65.498) = (11h 39m 42s, -65d 29m 53s) (J2000) with an error radius (statistical + systematic) of about 0.3 degrees. This location is consistent with that of the RS CVn star GT Mus (=4U 1137-65, HD 101379) (Garcia et al.

Nakajima, M.; Suwa, F.; Negoro, H.; Ozawa, H.; Matsumura, T.; Yamazaki, K.; Uzawa, A.; Kawai, N.; Mihara, T.; Serino, M.; Sugizaki, M.; Nakagawa, Y. E.; Yamamoto, T.; Sootome, T.; Matsuoka, M.; Morii, M.; Sugimori, K.; Usui, R.; Ueno, S.; Tomida, H.; Kohama, M.; Ishikawa, M.; Yoshida, A.; Yamaoka, K.; Nakahira, S.; Tsunemi, H.; Kimura, M.; Ueda, Y.; Isobe, N.; Eguchi, S.; Hiroi, K.; Shidatsu, M.; Daikyuji, A.

2010-11-01

53

Failure probabilistic model of CNC lathes  

Microsoft Academic Search

A field failure analysis of computerized numerical control (CNC) lathes is described. Field failure data was collected over a period of two years on approximately 80 CNC lathes. A coding system to code failure data was devised and a failure analysis data bank of CNC lathes was established. The failure position and subsystem, failure mode and cause were analyzed to

Yiqiang Wang; Yazhou Jia; Junyi Yu; Yuhua Zheng; Shangfeng Yi

1999-01-01

54

CNC Preparation Meets Manufacturing Opportunity  

ERIC Educational Resources Information Center

This article features the machining technology program at Cape Fear Community College (CFCC) of Wilmington, North Carolina. North Carolina's Cape Fear Community College is working to meet diverse industry needs through its CNC training. The school's program has gained the attention of the local manufacturing community and students when it shifted…

Cassola, Joel

2006-01-01

55

CNC Preparation Meets Manufacturing Opportunity  

ERIC Educational Resources Information Center

|This article features the machining technology program at Cape Fear Community College (CFCC) of Wilmington, North Carolina. North Carolina's Cape Fear Community College is working to meet diverse industry needs through its CNC training. The school's program has gained the attention of the local manufacturing community and students when it shifted…

Cassola, Joel

2006-01-01

56

Star Images, Star Performances (College Course File).  

ERIC Educational Resources Information Center

|Describes a course that focuses attention on the position of the actor, especially the star actor, in cinematic and television signification. Divides the course into three sections: "The Star System,""Stars as Images," and "Star Performance." (RS)|

Butler, Jeremy G.

1990-01-01

57

MAXI/GSC detection of a possible X-ray flare from an RS CVn star CF Tuc  

NASA Astrophysics Data System (ADS)

On 2012-01-30 08:25:38 UT (=MJD 55956.351), the MAXI/GSC transient alert system triggered on enhanced X-ray emission from the position consistent with the CF Tuc (RS CVn system). The significant X-ray flux in the 2-20 keV band had been detected at 2012-01-30 03:45 (UT)(=MJD 55956.157) and activity continued about 3 hours. The maximum X-ray flux and the luminosity are about 60 mCrab and 2×1033 ergs/s in 2-20 keV band, respectively, if the distance is assumed to be 89 pc.

Yamamoto, T.; Yamazaki, K.; Tsuboi, Y.; Nakahira, S.; Serino, M.; Mihara, T.; Sugizaki, M.; Sootome, T.; Matsuoka, M.; Ueno, S.; Tomida, H.; Kohama, M.; Ishikawa, M.; Kawai, N.; Morii, M.; Sugimori, K.; Usui, R.; Toizumi, T.; Aoki, Y.; Song, S.; Yoshida, A.; Yamaoka, K.; Tsunemi, H.; Kimura, M.; Kitayama, H.; Negoro, H.; Nakajima, M.; Suwa, F.; Asada, M.; Sakakibara, H.; Ueda, Y.; Hiroi, K.; Shidatsu, M.; Matsumura, T.; Yamauchi, M.; Nishimura, Y.; Hanayama, T.

2012-01-01

58

CNC electrical discharge machining centers  

SciTech Connect

Computer numerical control (CNC) electrical discharge machining (EDM) centers were investigated to evaluate the application and cost effectiveness of establishing this capability at Allied-Signal Inc., Kansas City Division (KCD). In line with this investigation, metal samples were designed, prepared, and machined on an existing 15-year-old EDM machine and on two current technology CNC EDM machining centers at outside vendors. The results were recorded and evaluated. The study revealed that CNC EDM centers are a capability that should be established at KCD. From the information gained, a machine specification was written and a shop was purchased and installed in the Engineering Shop. The older machine was exchanged for a new model. Additional machines were installed in the Tool Design and Fabrication and Precision Microfinishing departments. The Engineering Shop machine will be principally used for the following purposes: producing deep cavities in small corner radii, machining simulated casting models, machining difficult-to-machine materials, and polishing difficult-to-hand polish mold cavities. 2 refs., 18 figs., 3 tabs.

Jaggars, S.R.

1991-10-01

59

TX Cnc AS A MEMBER OF THE PRAESEPE OPEN CLUSTER  

SciTech Connect

We present B-, V-, and I-band CCD photometry of the W UMa-type binary system TX Cnc, which is a member star of the Praesepe open cluster. Based on the observations, new ephemeris and a revised photometric solution of the binary system were derived. Combined with the results of the radial velocity solution contributed by Pribulla et al., the absolute parameters of the system were determined. The mass, radius, and luminosity of the primary component are derived to be 1.35 {+-} 0.02 M {sub sun}, 1.27 {+-} 0.04 R {sub sun}, and 2.13 {+-} 0.11 L {sub sun}. Those for the secondary star are computed as 0.61 {+-} 0.01 M {sub sun}, 0.89 {+-} 0.03 R {sub sun}, and 1.26 {+-} 0.07 L {sub sun}, respectively. Based on these results, a distance modulus of (m - M) {sub V} = 6.34 {+-} 0.05 is determined for the star. It confirms the membership of TX Cnc to the Praesepe open cluster. The evolutionary status and the physical nature of the binary system are discussed compared with the theoretical model.

Zhang, X. B.; Deng, L.; Lu, P. [National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, 100012 Beijing (China)

2009-08-15

60

Composite Concrete Bed for CNC Machine Tool  

Microsoft Academic Search

As the operation speeds of CNC machine tools are increased, the vibration problem has become a major constraint of manufacturing of precision products. The two important functional requirements of CNC machine tool bed are high structural stiffness and high damping. Conventional metallic materials used for bed structure have high stiffness but low damping. Epoxy concrete materials used for bed structure

Ding Jiangmin

2010-01-01

61

Space curve interpolation for CNC machines  

Microsoft Academic Search

Despite the tremendous development in CNC programming facilities, linear and circular cuts parallel to the coordinate planes continue to be the standard motions of modern CNC machines. However, the increasing industrial demand for parts with intricate shapes cannot be satisfied with only these standard motions. This paper proposes an efficient and accurate method for developing a class of precise interpolation

Sotiris L. Omirou

2003-01-01

62

The photosphere and chromosphere of the RS Canum Venaticorum star, II Pegasi I. Spots and chromospheric emission in 1991.  

NASA Astrophysics Data System (ADS)

We report on high-resolution spectroscopy of the RSCVn binary IIPeg, along with contemporaneous UBV(RI)_KC_ photometry, including partly simultaneous U-band flare monitoring, during the third quarter of 1991. The spectroscopy was taken at two epochs separated by more than 6(1)/(2) weeks or seven rotations of IIPeg. At the first epoch we have observed the three chromospheric lines, H?, H? and HeID_3_, over a single rotation and at the second epoch we observed almost the entire visible region, for a substantial fraction of one rotation, including H?-H? and CaIIH. Our photometric results show that there was an unusually complicated spot distribution at this epoch, with at least three centres of activity discernable. We demonstrate, for the first time on a spotted late-type star, that these centres of spot activity have significantly different mean temperatures from one another. Furthermore, our derived spot temperatures are markedly lower than those previously derived from such multicolour photometry and more similar to those derived spectroscopically. Using multiple repeat exposures on each spectral line within each night, we are confident that we have derived a mean, non-flaring spectrum at each observational phase. Furthermore, the line flux variations at the two epochs repeat very well, suggesting that the mean global chromospheric structures are stable on a 1(1)/(2) months time scale. We discuss the implications of the mean spectra for the non-flaring atmosphere of IIPeg and conclude that, in the region of formation of the H? line, velocity fields are required to account for the line profile. These results suggest upward motions of the deep chromosphere with a less dramatic downflow in the high chromosphere. We examine the variation of the chromospheric line fluxes as a function of spot visibility and conclude that there is only a very loose spatial correlation of chromsopheric heating with spots. The motions suggested from the H? profile variations appear to be spot-associated.

Byrne, P. B.; Panagi, P. M.; Lanzafame, A. C.; Avgoloupis, S.; Huenemoerder, D. P.; Kilkenny, D.; Marang, F.; Panov, K. P.; Roberts, G.; Seiradakis, J. H.; van Wyk, F.

1995-07-01

63

Synthetical Reliability Analysis Model of CNC Software System  

NASA Astrophysics Data System (ADS)

CNC technology is the core of advanced manufacturing technology, and CNC software system is the very important part of numerical control system. The entire CNC system will not work normally, once the potential failure makes the software invalid. As to the current study of CNC sysytem, in use of the FAULT glitch tree, established a glitch tree for the CNC system; find the minimum cut sets with Fussed method and then according to the probability of several common glitches, make quantitative analysis in the reliability of the CNC system so that scientific ways can be provided for the reliability design, maintenance and management of the CNC system.

Xu, Yue; Xia, Yinjie; Wan, Yi

64

Intelligent CNC machine control system architecture.  

National Technical Information Service (NTIS)

Intelligent, agile manufacturing relies on automated programming of digitally controlled processes. Currently, processes such as Computer Numerically Controlled (CNC) machining are difficult to automate because of highly restrictive controllers and poor s...

D. J. Miller C. S. Loucks

1996-01-01

65

Multiband Photometric and Spectroscopic Analysis of HV Cnc  

NASA Astrophysics Data System (ADS)

In this paper, radial velocity and VI- and JHKS - (Two Micron All Sky Survey) band photometric data of the detached system HV Cnc have been analyzed. The primary component of HV Cnc, which is a member of the M67 cluster, is suspected to be either a blue straggler or turn-off star. The system is a single-lined spectroscopic binary and its light curve shows a total eclipse. Spectroscopic observations of the system revealed the third component, which shows contribution to the total light of the system. Light curve and radial velocity data have been analyzed using the Wilson-Devinney (W-D) code and JHKS filter definitions computed for the W-D code in this work. Our analysis shows that the mass and radius of the primary and secondary components are 1.31 M ?, 0.52 M ?, 1.87 R ?, and 0.48 R ?, respectively. All results are compared with previously published literature values and discussed.

Gökay, G.; Gürol, B.; Derman, E.

2013-11-01

66

Friction feedforward compensation and position feedforward in CNC machines  

Microsoft Academic Search

This research proposes a method to eliminate friction effect and reduced tracking error on CNC milling machines. A CNC milling machine has many connected mechanical components which have friction effects such as ball screws and rails. To control servo motors which are used to drive X-Y table in CNC milling machine, the conventional PID controller is widely used. In this

Wijin Suteeratanapirom; Rapeepong Rattanawaorahirankul; Chutima Laosapan; Peerayot Sanposh; Nattapon Chayopitak; Kanokvate Tungpimolrut; Hiroaki Kunieda

2010-01-01

67

Discovery of a white dwarf companion to the MS Star 4 omicron1 ORI  

NASA Astrophysics Data System (ADS)

While investigating the ultraviolet spectra of S stars, a hot compact companion to the MS star 4 omicron1 Ori was discovered. Fitting the continuum and L alpha profile to models and IUE observations of other white dwarfs, it is shown to be a DA3 star with Teff = 22,000 K. Assuming a luminosity equal to the field DA stars, M = -0.7 for the primary, somewhat fainter than M = -1.2 to -1.4 from other calibrations. In most respects, o1 Ori is an ordinary MS star, with typical values for the Ti/Zr, Li/Ca and Ti isotope ratios. One outstanding difference is the presence of Tc, which is not found in other non-Mira MS and S stars, but the secondary is not likely to be the source. Upper detection limits for hot companions to other bright MS stars are derived: HR 363, RS Cnc, ST Her and OP Her. The nondetection of evolved companions for these stars is consistent with the statistics of field giant binaries.

Johnson, H. R.; Ake, T. B.

1986-09-01

68

Very low luminosity stars with very large amplitude flares  

SciTech Connect

CCD frames of CZ Cnc, KY Cep, the gamma-ray burster optical transient, and NSV 12006 are analyzed. Also studied are 549 archival photographic plates of the CZ Cnc field. These observations are compared with the data of Lovas (1976). Flare events on CZ Cnc are examined. Based on the data it is noted that CZ Cnc is a main-sequence star, has a magnitude of 16.1, a distance of 100 pc, occasional large-amplitude flares, and frequent flares with amplitudes greater than 4 mag. 36 refs.

Schaefer, B.E. (NASA, Goddard Space Flight Center, Greenbelt, MD (USA))

1990-04-01

69

PRE-MACHINING CNC CONTOUR VALIDATION  

Microsoft Academic Search

The current procedure followed to manufacture a new part by CNC machining is to write the part program, machine a test part and measure the test part for conformance to the required dimensions and tolerances. If the test part dimensions are not correct, the part program is modified and the process repeated until a successful part is machined. In many

Tony Schmitz; John Ziegert

70

Stars  

NSDL National Science Digital Library

This section of the Windows to the Universe web site provides information and images about stars including star statistics, and a star gallery. Windows to the Universe is a user-friendly learning system pertaining to the Earth and Space sciences. The objective of this project is to develop an innovative and engaging web site that spans the Earth and Space sciences and includes a rich array of documents, including images, movies, animations, and data sets that explore the Earth and Space sciences and the historical and cultural ties between science, exploration and the human experience. Links at the top of each page allow users to navigate between beginner, intermediate and advanced levels.

Johnson, Roberta

2000-07-01

71

Developing an integrated STEP-compliant CNC prototype  

Microsoft Academic Search

STEP-compliant CNC is the next-generation CNC controller, taking the STEP-NC data model as the interface scheme between CAM and CNC and carrying out various intelligent functions. At the moment, efforts are being made worldwide to establish an international standard for the new interface scheme (so-called STEP-NC), formalized as ISO 14649. In the near future, the new interface scheme will be

S. H Suh; D. H Chung; B. E Lee; J. H Cho; S. U Cheon; H. D Hong; H. S Lee

2002-01-01

72

Catalogue of main characteristics of pulsations of 173 semi-regular stars  

NASA Astrophysics Data System (ADS)

The characteristics of brightness variations of 173 semi--regular stars are tabulated: the moments and brightness of the extrema; the effective periods, amplitudes and significance obtained by using different methods: a) the periodogram analysis (harmonic least squares fit) with prewhitening to determine characteristics and significance of waves with 3 periods; b) the wavelet analysis to determine characteristics of statistically significant waves; c) the "running parabola" scalegram analysis to determine the optimal filter half--width for smoothing. The characteristics may be used for more precise classification of semi-regular variables. Characteristics of the 6509 extrema of 147 stars are listed. The electronic version is available via http://ila.webjump.com. The observations for the analysis have been taken from the AFOEV and VSOLJ databases (with a duration up to 94 years) for the stars: AQ, EH, EK, RS, RU, RV, ST, TV, TY, TZ, UX, VX And; GY, PX, S, V, V844 Aql; V, Z Aqr; T Ari; AG, RS, S, UU, Z Aur; RV, RW, RX, RZ, U, V, WY Boo; T Cae; RR, RS, RY, S, ST, U Cam; RT Cap; PZ, SV, UX, V393, V465, WZ Cas; T, Y Cen; AR, RU, RW, RX, SS, TY, W Cep; T Cet; RS, RT, T, X Cnc; RR, RS, TT CrB; V, Y Cvn; AA, AF, AI, AV, AW, BC, RS, RU, RV, RW, RZ, TT, V460, W Cyg; EU, U Del; RS, RY, S, TX, UX, WZ Dra; SY, Z Eri; IS, NQ, RS, SW, TU, TV, Y Gem; DE, MZ, RR, ST, SX, UU, X Her; FF, RT, U, V, W, Y Hya; RS Lac; RY, SX Leo; RX, S Lep; U, W LMi; Y, EG, R, SZ Lyr; RV, SW, X Mon; V759 Oph; BQ, FX, GT, RT, W Ori; AF, AK, SV, TX Peg; AD, BU, DY, FZ, RS, RU, S, SU, SY, T, UZ, W, XX Per; R Pic; RT, RW, Z Psc; BM Sco; S Sct; FG Ser; X Sge; AB, TT, W, Y Tau; W Tri; RX, RY, RZ, ST, SV, V, Y, Z UMa; R, V UMi; RT, SS, SW Vir; RU Vul.

Chinarova, L. L.; Andronov, I. L.

2000-12-01

73

The Blue Straggler RS Canum Venaticorum Star S1082 in M67: A Detailed Light Curve and the Possibility of a Triple  

NASA Astrophysics Data System (ADS)

Using both photometric and spectroscopic data, we present a picture of the very unusual blue straggler S1082 in the old open cluster M67 whose light is the sum of a close binary (P=1.0677978 days) and another cluster member. The primary of the close binary and the third star are both blue stragglers in their own rights. Using relative photometry with millimagnitude accuracy, we provide a complete V-band light curve for the system and show a number of unusual features: brightness variations at the 0.01-0.03 mag level from month to month at all phases, a narrow primary and broad secondary eclipse, brightness differences between phases 0.25 and 0.75, and short duration (~1 hr) drops in brightness. Much of the light-curve variation appears to be because of spot activity on the cooler, fainter, nearly synchronized component of the close binary. We use spectra from several sources to constrain the temperatures of the three known components, the relative flux contributions, rotational velocities, and radial velocities. The data clearly show that the brightest star (narrow-line component) seen in the spectrum is on an orbit with period P=1189+/-7 days and eccentricity e=0.57+/-0.08, although we cannot prove that there is a dynamical link between it and the close binary. The systematic velocities of all of the stars indicate that they are members of the cluster. Our models of the system indicate that the cooler component of the close binary lies on the main sequence near the cluster turnoff, while the hotter component lies near an extension of the main sequence blueward of the turnoff, and thus qualifies as a blue straggler by itself. The reduction of the masses of the stars in the close binary compared with previous models indicates that it is possible that the more massive component of the close binary formed from a merger of just two turnoff-mass stars. Based in part on observations obtained with the Hobby-Eberly Telescope (HET), which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximillians-Universität München, and Georg-August-Universität Göttingen. The HET is named in honor of its principal benefactors, William P. Hobby and Robert E. Eberly.

Sandquist, Eric L.; Latham, David W.; Shetrone, Matthew D.; Milone, Alejandra A. E.

2003-02-01

74

ULTRACAM photometry of the eclipsing cataclysmic variables GY Cnc, IR Com and HT Cas  

NASA Astrophysics Data System (ADS)

We present high-speed, three-colour photometry of the eclipsing cataclysmic variables GY Cnc, IR Com and HT Cas. We find that the sharp eclipses in GY Cnc and IR Com are due to eclipses of the white dwarf. There is some evidence for a bright-spot on the edge of the accretion disc in GY Cnc, but not in IR Com. Eclipse mapping of HT Cas is presented which shows changes in the structure of the quiescent accretion disc. Observations in 2002 show the accretion disc to be invisible except for the presence of a bright-spot at the disc edge. 2003 observations, however, clearly show a bright inner disc and the bright-spot to be much fainter than in 2002. Although no outburst was associated with either set of quiescent observations, the system was ~0.6mJy brighter in 2003, mainly due to the enhanced emission from the inner disc. We propose that these changes are due to variations in the mass-transfer rate from the secondary star and through the disc. The disc colours indicate that it is optically thin in both its inner and outer regions. We estimate the white dwarf temperature of HT Cas to be 15000 +/- 1000K in 2002 and 14000 +/- 1000K in 2003.

Feline, W. J.; Dhillon, V. S.; Marsh, T. R.; Watson, C. A.; Littlefair, S. P.

2005-12-01

75

Rotational Modulation and Flares on Rs-Canum and By-Draconis Stars - Part Seventeen - Ultraviolet Spectroscopy and Optical Photometry of Au-Microscopii in 1986  

NASA Astrophysics Data System (ADS)

We present IUE spectroscopy and optical photometry of the active late type star AU Mic. The UV spectroscopy allow us to measure the chromospheric and transition region line fluxes. No detectable variations attributable to rotational modulation were evident in either the chromospheric lines or optical bands. We have produced an emission measure curve for the quiescent state of AU Mic, which spans a temperature range 4.0 ? log Te ? 7.6 when coupled with previous X-ray flux measurements. The quiescent radiative losses per unit surface area over the above temperature range is ?8 1O7 erg cm-2 s-1

Quin, D. A.; Doyle, J. G.; Butler, C. J.; Byrne, P. B.; Swank, J. H.

1993-05-01

76

Circumstellar Dust Disks around Stars with Known Planetary Companions  

Microsoft Academic Search

We have searched six stars with known radial velocity planetary companions for circumstellar disks. Disks are expected around stars with planetary systems that accreted from regular protoplanetary disks, and remnant disks are expected to be similar to our solar systems Kuiper Belt. To date, we have detected circumstellar disks around three such stars: 55 Cnc, o CrB, and HD 210277.

D. E. Trilling; R. H. Brown; A. S. Rivkin

2000-01-01

77

Understanding and Writing G & M Code for CNC Machines  

ERIC Educational Resources Information Center

|In modern CAD and CAM manufacturing companies, engineers design parts for machines and consumable goods. Many of these parts are cut on CNC machines. Whether using a CNC lathe, milling machine, or router, the ideas and designs of engineers must be translated into a machine-readable form called G & M Code that can be used to cut parts to precise…

Loveland, Thomas

2012-01-01

78

CNC Turning Technician. A Competency-Based Instructional System.  

ERIC Educational Resources Information Center

This competency-based curriculum guide for instructing students in using computer numerically controlled (CNC) turning machines is one of a series of instructional guides for the machinist field developed in Oklahoma. Although developed jointly with Baxter Technologies Corporation and oriented toward the Baxter Vo-Tec 2000 Future Builder CNC

Sloan, Kelly; Hilley, Robert

79

Advanced CNC Programming (EZ-CAM). 439-366.  

ERIC Educational Resources Information Center

This document contains two units for an advanced course in computer numerical control (CNC) for computer-aided manufacturing. It is intended to familiarize students with the principles and techniques necessary to create proper CNC programs using computer software. Each unit consists of an introduction, instructional objectives, learning materials,…

Casey, Joe

80

Strategic advantages of interoperability for global manufacturing using CNC technology  

Microsoft Academic Search

In the domain of manufacturing, computer numerically controllers (CNC) technology is a major contributor to the production capacity of the enterprises. The advances in CNC technology coupled with enhancements in computing systems have provided the basis to re-examine the way in which computer-aided systems (CAx) can be used to enable global manufacturing. Interoperability of the various components of the CAx

S. T. Newman; A. Nassehi; X. W. Xu; R. S. U. Rosso; L. Wang; Y. Yusof; L. Ali; R. Liu; L. Y. Zheng; S. Kumar; P. Vichare; V. Dhokia

2008-01-01

81

CNC Turning Technician. A Competency-Based Instructional System.  

ERIC Educational Resources Information Center

|This competency-based curriculum guide for instructing students in using computer numerically controlled (CNC) turning machines is one of a series of instructional guides for the machinist field developed in Oklahoma. Although developed jointly with Baxter Technologies Corporation and oriented toward the Baxter Vo-Tec 2000 Future Builder CNC

Sloan, Kelly; Hilley, Robert

82

Advanced CNC Programming (EZ-CAM). 439-366.  

ERIC Educational Resources Information Center

|This document contains two units for an advanced course in computer numerical control (CNC) for computer-aided manufacturing. It is intended to familiarize students with the principles and techniques necessary to create proper CNC programs using computer software. Each unit consists of an introduction, instructional objectives, learning…

Casey, Joe

83

Fault tolerance of CNC software based on artificial neural network  

Microsoft Academic Search

This paper proposes an efficient method for realizing the fault tolerance of CNC software with the introduction of artificial neural network (ANN) to the design filed of CNC software. In addition, function aspects (velocity, acceleration, chord error, real time, prediction accuracy) from the experiment on Non-Uniform Rational B-Spline (NURBS) interpolator based on ANN were evaluated in detail. Our experimental results

Xiu-Hua Yuan; Yi-Qiang Wang; Yan-Juan Hu

2010-01-01

84

Based on Industrial Ethernet Networking of CNC Machine Tool Monitoring System Design  

Microsoft Academic Search

CNC machine tools of networking and information-oriented are the requests which the modern society develops. Networking Method of CNC machine tools has many kinds. This article describes several networking mode and Analysis of the Ethernet networking of CNC machine tool control system design advantages of. And Introduced the Ethernet-based networking remote monitoring system for CNC machine tools and design principles.

Zhang Zhong-jie

2010-01-01

85

Study of Accuracy of CNC Machine Tools  

NSDL National Science Digital Library

The dimensional accuracies as well as surface finishes of parts produced by a CNC machine tool are strongly dependent on the motion accuracy of each axis of the machine. The overall accuracy of the machine tool is decided by the mechanical characteristics of the machine as well as the characteristics if the control system driving the individual axes. A CNC Machine is programmed to travel along a predetermined or contour, and any deviation from the programmed path is referred as the contouring error. A typical test that is used is a circular test in which the machine is programmed to travel along a circle, and the difference between the programmed path and the measured actual path is compared. The purpose of this study is to identify the various contributors to this contouring error, and in particular estimate the error due to stick slip motion using analytical techniques. It is planned to measure the errors experimentally making use of capacitance probes. The study is intended to develop an appreciation for the sources of different errors produced in a machine tool and as such forms a module in a typical semester long class devoted to manufacturing processes.

Chattopadhyay, Sonnath

2009-09-10

86

New ephemerides for 120 eclipsing binary stars  

NASA Astrophysics Data System (ADS)

New ephemerides based on data from 1968 to 1978 have been derived for 120 eclipsing binary stars with Algol-like light curves. The original visual timings are grouped into yearly normals of rather high accuracy. The program stars are: RT And, UU And, xZ And, RY Aqr, CX Aqr, CZ Aqr, EE Aqr, V346 Aql, WW Aur, UW Boo, ZZ Boo, Y Cam, SV Cam, AL Cam, TU Cnc, R CMa, RX CMa, TU CMa, AG CMi, TV Cap, Rz Cas, TV Cas, AB Cas, U Cep, EG Cep, RW Cet, U CrB, V Crt, Y Cyg, SW Cyg, UW Cyg, WW Cyg, zZ Cyg, AE Cyg, V456 Cyg, V477 Cyg, V687 Cyg, V728 Cyg, W Del, TY Del, YY Del, FZ Del, Z Dra, RR Dra, TW Dra, A' Dra, S Equ, TZ Eri, WX Eri, RW Gem, TX Gem, YY Gem, AF Gem, RX Her, SZ Her, TU Her, TX Her, UX Her, CC Her, CT Her, V338 Her, RX Hya, TW Lac, VX Lac, AU Lac, CM Lac, Y Leo, RW Leo, UU Leo, UV Leo, T LMi, RS Lep, Lib, UZ Lyr, EW Lyr, FL Lyr, RW Mon, TU Mon, BO Mon, U Oph, RV Oph, V449 Oph, FL Ori, FT Ori, UX Peg, BN Peg, DI Peg, Z Per, RT Per, RV Per, ST Per, xZ Per, p Per, Y Psc, xZ Pup, U Sge, XY Sgr, V505 Sgr, RS Sct, AK Ser, AO Ser, RW Tau, HU Tau, X Tri, TX UMa, UX UMa, vV UMa, xZ UMa, zZ UMa, W UMi, RU UMi, UW Vir, AK Vir, BF Vir, BH Vir, Z Vul, AX Vul, BE Vul, BO Vul, and BU Vul.

Mallama, A. D.

1980-10-01

87

Close binary and other variable stars in the solar-age Galactic open cluster M 67  

NASA Astrophysics Data System (ADS)

We present multi-colour time-series CCD photometry of the solar-age galactic open cluster M 67 (NGC 2682). About 3600 frames spread over 28 nights were obtained with the 1.5 m Russian-Turkish and 1.2 m Mercator telescopes. High-precision observations of the close binary stars AH Cnc, EV Cnc, ES Cnc, the ? Scuti type systems EX Cnc and EW Cnc, and some long-period variables belonging to M 67 are presented. Three full multi-colour light curves of the overcontact binary AH Cnc were obtained during three observing seasons. Likewise we gathered three light curves of EV Cnc, an EB-type binary, and two light curves of ES Cnc, a blue straggler binary. Parts of the light change of long-term variables S1024, S1040, S1045, S1063, S1242, and S1264 are obtained. Period variation analysis of AH Cnc, EV Cnc, and ES Cnc were done using all times of mid-eclipse available in the literature and those obtained in this study. In addition, we analyzed multi-colour light curves of the close binaries and also determined new frequencies for the ? Scuti systems. The physical parameters of the close binary stars were determined with simultaneous solutions of multi-colour light and radial velocity curves. Finally we determined the distance of M 67 as 857(33) pc via binary star parameters, which is consistent with an independent method from earlier studies. Based on observations made with the Mercator Telescope, operated on the island of La Palma by the Flemish Community, at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias and TÜB?TAK National Observatory Russian-Turkish telescope operated at Sakl?kent, Antalya.

Yakut, K.; Zima, W.; Kalomeni, B.; van Winckel, H.; Waelkens, C.; De Cat, P.; Bauwens, E.; Vu?kovi?, M.; Saesen, S.; Le Guillou, L.; Parmaks?zo?lu, M.; Uluç, K.; Khamitov, I.; Raskin, G.; Aerts, C.

2009-08-01

88

Infrared colors of RS CVn binaries  

Microsoft Academic Search

IRAS 1D COADD data for 82 RS CVn systems have been analysed to obtain their magnitudes at 12 and 25 micrometers. Their colors V - (12) and (12) - (25) have been computed and discussed. For 62 stars, the excess at 12 micrometers has been derived using the information on the spectral type of their binary components and measured colors

T. N. Rengarajan; R. P. Verma; K. V. K. Iyengar

1993-01-01

89

Optical, UV and Radio Observations of RS Canum Venaticorum  

NASA Astrophysics Data System (ADS)

Preliminary results are reported on optical, UV and radio observations of the binary system RS Canum Venaticorum carried out in March 1984, as a part of the international coordinated programme on solar-like activity in late type stars.

Catalano, S.; Rodono, M.; Linsky, J. L.; Carpenter, K.; Gibson, D.; Gary, D.; Butler, J.

90

Far Ultraviolet Spectroscopy of Three Long Period Nova-Like Variables, V363 Aur, AC Cnc and RZ Gru  

NASA Astrophysics Data System (ADS)

We have selected three nova-like variables: V363 Aur, RZ Gru and AC Cnc, all of which are UX UMa types, having similar orbital periods well beyond the 3 to 4 hour range where most nova-likes are found. All should have very similar secondary stars given the fact that they their physical parameters are so similar. V363 Aur is a bona fide SW Sex star, and AC Cnc is a probable one, while RZ Gru is not a member of the SW Sex subclass. Our objective is to carry out the first synthetic spectral analysis of far ultraviolet spectra of the three systems using state-of-the-art models both of accretion disks and photospheres. Therefore we shall compare the distances we obtain from the best fitting synthetic spectral models to other distance estimates in the literature. We present model-derived accretion rates and distances for all three systems. The FUV flux range of RZ Gru and V363 Aur is dominated by radiation from an optically thick, steady state, accretion but for AC Cnc, we find that a hot white dwarf accounts for 70% of the FUV flux. We compare the FUV characteristics and physical properties of these three long period nova-like systems to the properties of other nova-likes at shorter periods. This work was supported in part by NSF grant AST0807892 to Villanova University.

Bisol, Alexandra; Sion, E. M.

2011-01-01

91

EINSTEIN observations of BY Draconis variables and RS CVn binaries  

SciTech Connect

Observations of five BY Draconis variables and four RS Canum Venaticorum systems with the Einstein observatory are presented. All nine stars were detected. Although the BY Draconis stars have an average x-ray luminosity one to two orders of magnitude lower than the RS CVn binaries, at least three of these systems fit the L/sub x//L/sub bol/-vs-period relation first described by Walter and Bowyer for RS CVn's. Since one of the BY Draconis stars is almost certainly single, this result lends strong support to the suggestion that rapid rotation, and not duplicity, is the determining factor in defining the level of stellar activity in such stars. In addition, the x-ray data are consistent with the suggestion, made by Vogt and Fekel, that the BY Draconis stars are in the final stages of pre-main-sequence evolution.

Caillault, J.

1982-03-01

92

Generation of Gear Tooth Surfaces by Application of CNC Machines.  

National Technical Information Service (NTIS)

This study will demonstrate the importance of application of computer numerically controlled (CNC) machines in generation of gear tooth surfaces with new topology. This topology decreases gear vibration and will extend the gear capacity and service life. ...

F. L. Litvin N. X. Chen

1994-01-01

93

Resonance line of B II in IUE spectra of chemically peculiar stars  

SciTech Connect

High-dispersion IUE spectroscopic observations of the B II resonance line at 1362.46 A are presented for six HgMn stars (kappa Cnc, ..mu.. Lep, 46 Draiola, CrB, HR 4072, and chi Lup), two magnetic peculiar stars (..cap alpha../sup 2/ CVn and HD 32633), and one normal B9.5 V star (..nu.. Cap). The B II line is present in great strength in kappa Cnc. It is absent from the five other HgMn stars. It is probably present, though unresolved and weak, in the magnetic stars. Its strength in ..nu.. Cap is consistent with a normal boron abundance.

Leckrone, D.S.

1981-11-15

94

A high speed machining algorithm for CNC machine tools  

Microsoft Academic Search

This paper introduces a high speed machining algorithm based on a look-ahead interpolation technique for the machining of 3D surface obtained by a CAD\\/CAM system. Generally, specification of CNC system for high speed machining requires an additional hardware and it burdens end users with additional cost. The purpose of this research is to develop the low cost CNC controller having

Guk-Chan Han; Dong-II Kim; Hyo-Gyu Kim; Kibeohn Nam; Byeong-Kap Choi; Sung-Kwun Kim

1999-01-01

95

CNC tool path in terms of B-spline curves  

Microsoft Academic Search

We present an accurate and efficient method to generate a CNC tool path for a smooth free-form surface in terms of planar cubic B-spline curves which will be fed into a free-form curve interpolator. We assume the use of a three-axis CNC machine tool with a ball end-mill cutter. We first interpolate break points, which are generated by computing the

Claire Lartigue; François Thiebaut; Takashi Maekawa

2001-01-01

96

An active axis control system for a conventional CNC machine  

Microsoft Academic Search

A non-invasive approach to implement an active axis controller for a conventional CNC machine is presented. To develop the system a two-stage approach has been taken. In stage one, a generic external axis controller is designed to bring the machine under the real-time control of an external computer. The external controller is interfaced to the CNC machine via the Manual

Daniel Hanafi; Michal Tordon; Jayantha Katupitiya

2003-01-01

97

Variable Feedrate CNC Interpolation for Planar Implicit Curves  

Microsoft Academic Search

The machining of planar implicit curves is common in computer numerical control (CNC) machining. It is usually carried out\\u000a through approximating these curves as segments of straight line\\/circular arc for CNC interpolation. This paper considers real-time\\u000a variable feedrate interpolation of planar implicit curves. Geometric entities of planar implicit curves were related to motion\\u000a entities along the curve. The results were

H.-Y. Xu; H.-Y. Tam; Z. Zhou; P. W. Tse

2001-01-01

98

Implementation of online NURBS curve fitting process on CNC machines  

Microsoft Academic Search

The study aims to develop a method for implementing an online non-uniform rational B-spline (NURBS) curve fitting process\\u000a on CNC machines for improving the quality and efficiency of machining. Conventional CAD\\/CAM\\/CNC systems usually induce some\\u000a machining difficulties and limit the machining results in real applications. Therefore, some researchers have proposed various\\u000a methods for improving the machining results. An online NURBS

Syh-Shiuh Yeh; Hsin-Chuan Su

2009-01-01

99

Accurate feedrate control of CNC machine tools along NURBS curves  

Microsoft Academic Search

This paper presents a feedrate-controlled interpolator for accurate feedrate control of CNC machine tools along NURBS curves for precision CNC machining. Unlike most existing interpolators, usually based on the Taylor expansion, the proposed method uses an Adams-Moulton predictor-corrector algorithm instead. An upper bound on the sampling interval is established, which guarantees convergence of the corrector iterations (within each interval). Experimental

Chung-Wei Cheng; Mi-Ching Tsai; Jan Maciejowski

2004-01-01

100

Real-time CNC interpolators for Pythagorean-hodograph curves  

Microsoft Academic Search

CNC machining requires “interpolation” algorithms that accurately and efficiently generate sequences of reference positions, distributed according to a prescribed feedrate function, along the tool paths. CNC interpolators have traditionally accommodated only linear and circular trajectories, on account of the absence of easily-calculable relations between the arc length s and parameter ? for free-form parametric curves. With the Pythagorean-hodograph (PH) curves,

Rida T. Farouki; Sagar Shah

1996-01-01

101

Design of NURBS Curve Fitting Process on CNC Machines  

Microsoft Academic Search

This study aims to design a method for implementing the non-uniform rational B-spline (NURBS) curve fitting process on CNC machines for improving the machining quality and efficiency. The conventional CAD\\/CAM\\/CNC systems usually induce some machining problems and limit the machining results in real applications. An on-line NURBS curve fitting process consists of fetching and fitting stages is developed in this

Syh-Shiuh Yeh; Shin-Chun Su

2007-01-01

102

CNC grinding of valve housing piston holes  

SciTech Connect

Grinding has traditionally been used for machining operations requiring close dimensional tolerances and better surface finishes than can be obtained from other metal removal techniques. Using a grinding process for the last metal removal operation, the close tolerances and surface finishes can be easily held while eliminating the adverse conditions from the current metal removal processes. Pre-machined test parts were sent to a machine tool supplier to have the critical inside features of a typical piston bore finish machined using an internal CNC grinder equipped with high-frequency spindles. The piston bore and sealing angle were ground using a standard 120-grit silicon carbide wheel. The wafer step was machined using a solid carbide tool designed and built at Allied-Signal Inc., Kansas City Division (KCD). Six consecutive parts were machined for evaluation. The repeatability on all six parts was within print requirements. The inside corner radii was less than 0.002 in. and the surface finish was 8.2 arithmetical average or better as defined by ANSI B46.1, Surface Texture. Machining parts by this grinding process would eliminate bellmouth, chatter, waviness, and traveler polishing operations. It would produce a superior surface finish, small inside radii, and small easily removable burrs. It would also hold tolerances closer and significantly reduce scrap, rework, rejects, and deviations. 1 fig.

Ashbaugh, F.A.

1991-11-01

103

Final Report: CNC Micromachines LDRD No.10793  

SciTech Connect

The three-year LDRD ''CNC Micromachines'' was successfully completed at the end of FY02. The project had four major breakthroughs in spatial motion control in MEMS: (1) A unified method for designing scalable planar and spatial on-chip motion control systems was developed. The method relies on the use of parallel kinematic mechanisms (PKMs) that when properly designed provide different types of motion on-chip without the need for post-fabrication assembly, (2) A new type of actuator was developed--the linear stepping track drive (LSTD) that provides open loop linear position control that is scalable in displacement, output force and step size. Several versions of this actuator were designed, fabricated and successfully tested. (3) Different versions of XYZ translation only and PTT motion stages were designed, successfully fabricated and successfully tested demonstrating absolutely that on-chip spatial motion control systems are not only possible, but are a reality. (4) Control algorithms, software and infrastructure based on MATLAB were created and successfully implemented to drive the XYZ and PTT motion platforms in a controlled manner. The control software is capable of reading an M/G code machine tool language file, decode the instructions and correctly calculate and apply position and velocity trajectories to the motion devices linear drive inputs to position the device platform along the trajectory as specified by the input file. A full and detailed account of design methodology, theory and experimental results (failures and successes) is provided.

JOKIEL JR., BERNHARD; BENAVIDES, GILBERT L.; BIEG, LOTHAR F.; ALLEN, JAMES J.

2003-04-01

104

A novel CNC aspheric grinding machine  

NASA Astrophysics Data System (ADS)

Aspheric surface can be thought as being enveloped by a series of spherical surfaces with their centres on the same axis but having different positions. These spherical surfaces are tangent with the aspheric surface. We have manufactured a ?600 CNC aspheric grinding machine with this novel operating principle. We choose ?p , ? and ?p as the key parameters of our grinding machine. ?p is the distance between the cup-shaped tools' bottom and the vertex of the aspheric surface. ?p is the rotational angle of the cup-shaped tool. ? is the space angle of the cup-shaped tool during the fabrication process of convex aspheric surface. Using this grinding machine, we can fabricate a conic concave aspheric surface continuously about three hours. But we need change the cup-shaped tool one time when we fabricate a conic convex aspheric surface in also about three hours. Our grinding machine can also be used to fabricate high-order aspheric surface. We used this machine fabricating a RC telescope system's primary and the secondary mirror. The PV-value is less than 5?m for the primary ?350 concave hyperbolic aspheric surface which departure is about 55?m. We can polish and finish this aspheric surface with these residual errors easily. The manufacturing cost of the machine is about 300,000 RMB which is 1/10 of the LOH's product with the same maximum aperture of workpiece.

Hu, Jianjun; Pan, Junhua

2005-12-01

105

78 FR 50135 - CNC Development, Ltd., Exousia Advanced Materials, Inc., and South American Minerals, Inc.; Order...  

Federal Register 2010, 2011, 2012, 2013

...SECURITIES AND EXCHANGE COMMISSION [File No. 500-1] CNC Development, Ltd., Exousia Advanced Materials, Inc., and...current and accurate information concerning the securities of CNC Development, Ltd. because it has not filed any periodic...

2013-08-16

106

The Hot Component of RS Ophiuchi  

Microsoft Academic Search

We analyze optical and ultraviolet spectrophotometry of the quiescent recurrent nova RS Ophiuchi. Our preferred model for this binary consists of an M-type giant and a B-type shell star with a luminosity of Lh˜100-600 Lsun. The ejecta from the recent outburst are slightly enhanced in helium relative to the solar abundance, which agrees with previous estimates from model fits to

Danuta Dobrzycka; Scott J. Kenyon; Daniel Proga; Joanna Mikolajewska; Richard A. Wade

1996-01-01

107

Single CNC machine scheduling with controllable processing times to minimize total weighted tardiness  

Microsoft Academic Search

Advanced manufacturing technologies, such as CNC machines, require significant investments, but also offer new capabilities to the manufacturers. One of the important capabilities of a CNC machine is the controllable processing times. By using this capability, the due date requirements of customers can be satisfied much more effectively. Processing times of the jobs on a CNC machine can be easily

M. Selim Akturk; Taylan Ilhan

2011-01-01

108

Making CNC machine tools more open, interoperable and intelligent - a review of the technologies  

Microsoft Academic Search

The aim of the next generation of computer numerically controlled (CNC) machines is to be portable, interoperable and adaptable. Over the years, G-codes (ISO 6983) have been extensively used by the CNC machine tools for part programming and are now considered as a bottleneck for developing next generation of CNC machines. A new standard known as STEP-NC is being developed

X. W. Xu; Stephen T. Newman

2006-01-01

109

A fast tool servo design for precision turning of shafts on conventional CNC lathes  

Microsoft Academic Search

A technique for precision turning of shafts on conventional CNC turning centers is presented. The shaft is semi-turned on a conventional CNC lathe. The precision finish turning operation is delivered by a piezoelectric based fast tool servo which is mounted on the same CNC lathe's turret. The precision tool tip motion is delivered by a proposed sliding mode controller which

Wen-Hong Zhu; Martin B. Jun; Yusuf Altintas

2001-01-01

110

CNC Turning Center Advanced Operations. Computer Numerical Control Operator/Programmer. 444-332.  

ERIC Educational Resources Information Center

This student guide provides materials for a course designed to introduce the student to the operations and functions of a two-axis computer numerical control (CNC) turning center. The course consists of seven units. Unit 1 presents course expectations and syllabus, covers safety precautions, and describes the CNC turning center components, CNC

Skowronski, Steven D.; Tatum, Kenneth

111

Study on contour error related to dynamic parameters of CNC machine tool  

Microsoft Academic Search

As the contour error on cutting part is closely related to the dynamic parameters of CNC machine tool, which are usually refered to the dynamic accuracy, this paper presents a way to identify the shift of dynamic parameters with special shape feature. By modeling control system of CNC machine tool, the dynamic accuracy parameters of CNC machine tool are selected

Xie Dong; Ding Jiexiong; Huo Yanbo; Wang Wei; Du Li; Song Zhiyong; Shi Rongbo

2011-01-01

112

CNC Turning Center Advanced Operations. Computer Numerical Control Operator/Programmer. 444-332.  

ERIC Educational Resources Information Center

|This student guide provides materials for a course designed to introduce the student to the operations and functions of a two-axis computer numerical control (CNC) turning center. The course consists of seven units. Unit 1 presents course expectations and syllabus, covers safety precautions, and describes the CNC turning center components, CNC

Skowronski, Steven D.; Tatum, Kenneth

113

A Study of Intelligent Integrated Nano CNC System Based on Standard  

Microsoft Academic Search

In order to meet increased demand of nano machining accuracy in modern manufacturing industries, intelligent nano computer numerically controlled (CNC) system will be the main development aim of the next generation CNC system. Because traditional G-codes (ISO6983) have been extensively used by the CNC machine tools for part programming and are now considered as a bottleneck for machine tools, a

Tao Yu; Junxi Bi; Lilan Liu

2006-01-01

114

Robustness of thermal error compensation model of CNC machine tool  

NASA Astrophysics Data System (ADS)

Thermal error is the major factor in restricting the accuracy of CNC machining. The modeling accuracy is the key of thermal error compensation which can achieve precision machining of CNC machine tool. The traditional thermal error compensation models mostly focus on the fitting accuracy without considering the robustness of the models, it makes the research results into practice is difficult. In this paper, the experiment of model robustness is done in different spinde speeds of leaderway V-450 machine tool. Combining fuzzy clustering and grey relevance selects temperature-sensitive points of thermal error. Using multiple linear regression model (MLR) and distributed lag model (DL) establishes model of the multi-batch experimental data and then gives robustness analysis, demonstrates the difference between fitting precision and prediction precision in engineering application, and provides a reference method to choose thermal error compensation model of CNC machine tool in the practical engineering application.

Lang, Xianli; Miao, Enming; Gong, Yayun; Niu, Pengcheng; Xu, Zhishang

2013-01-01

115

Design and performance of a small precision CNC turning machine  

Microsoft Academic Search

This paper describes the design of a CNC turning machine that is capable of machining workpieces up to 100 mm in diameter with a high contour accuracy and a very low surface roughness. Two nearly identical machines have been built and put into operation using this design, one for serial parts manufacture and the other for research into improving the

R. R. Donaldson; D. C. Thompson; E LOEWEN

1986-01-01

116

Simulation of thermal behavior of a CNC machine tool spindle  

Microsoft Academic Search

The thermal deformations of a CNC machine tool spindle are the major contributor of thermal error. It is very significant both theoretically and practically to study how to accurately simulate the thermal error of the spindle. Firstly, this paper proposes a method for computing the coefficient of convection heat transfer of the spindle surface by referencing the theory on computing

Zhao Haitao; Yang Jianguo; Shen Jinhua

2007-01-01

117

Forming strategies and Process Modelling for CNC Incremental Sheet Forming  

Microsoft Academic Search

Incremental Sheet Forming (ISF) is a process capable of producing complex sheet components by the CNC movement of a simple tool in combination with simplified dies. Earlier work revealed two major process limits, namely the limitation on the maximum achievable wall angle, and the occurrence of geometric deviations. The work detailed in this paper focuses on forming strategies to overcome

G. Hirt; J. Ames; M. Bambach; R. Kopp

2004-01-01

118

Fidget with Widgets: CNC Activity Introduces the Flatbed Router  

ERIC Educational Resources Information Center

|The computer numerical control (CNC) flatbed router is a powerful tool and a must-have piece of equipment for any technology education program in which students will produce a product--whether it involves Manufacturing, Materials Processing, or any of the vast array of Project Lead the Way courses. This article describes an activity--producing a…

Tryon, Daniel V.

2006-01-01

119

A Cascaded Adaptive Controller for CNC Lathe Spindle Drives  

Microsoft Academic Search

In modern computer numerically controlled (CNC) lathes the spindle drives often have an infinitely variable speed range to allow constant horsepower cutting. Such spindle drives are typically powered by direct current (dc) servo motors which are conventionally controlled by an analog speed regulator in the form of pseudo-derivative feedback (PDF). The PDF controller contains an integral action to compensate for

H. A. Pak

1988-01-01

120

Parametric curve machining of a CNC milling EDM  

Microsoft Academic Search

A buffered digital differential analyzer (BDDA) algorithm in a computerized numerical controller (CNC) performs milling electric discharge machining (milling EDM'ing) of a curve constructed from a sequence of segments using a traditional computer-aided manufacturing (CAM) system. The proposed algorithm interpolates more than one segment in a sampling interval and supports the effective machining of a parametric curve when the electrode

Yih-Fang Chang; Rong-Chi Hong

2005-01-01

121

Real-time CNC interpolators for Bézier conics  

Microsoft Academic Search

Arbitrary conic segments can be specified in the rational B'ezier form,r() for 2 [ 0; 1 ], by control points p 0 ; p 1 ; p 2 and a scalar weight w 1 .An expression for the cumulative arc length function s(), amenable toaccurate and efficient evaluation, is required in formulating real--timeCNC interpolators capable of achieving a desired (constant

Carla Manni; Alessandra Sestini

2001-01-01

122

Electrophotometry of variable stars  

NASA Astrophysics Data System (ADS)

Sample observations of eclipsing variables made in Berlin, Germany, using a 25-cm Schmidt-Cassegrain telescope and an electric photometer with an EMI 9781B tube and UBV filters are presented, with the aim of demonstrating the usefulness and attainable precision of amateur observations of these stars. The photometer calibration procedure is outlined, and light curves of XY Leo, WW CnC, SAO 072799, BM Cas, V695 Gyg, Zeta And, RX Cas, and the 'c' object in Lynx (discovered by Frank in January, 1983) are discussed. The latter is found in preliminary observations to have a period of 0.197 day (assuming it is an eclipsing binary), and the fact that its B minimum occurs about 4 min later than its V minimum suggests that it may be a Delta-Scuti-type binary containing an A star. It is pointed out that a large number of unmeasured variable stars are of sufficient brightness for amateur photometric observations.

Fernandes, M.

1983-09-01

123

Generation of gear tooth surfaces by application of CNC machines  

NASA Astrophysics Data System (ADS)

This study will demonstrate the importance of application of computer numerically controlled (CNC) machines in generation of gear tooth surfaces with new topology. This topology decreases gear vibration and will extend the gear capacity and service life. A preliminary investigation by a tooth contact analysis (TCA) program has shown that gear tooth surfaces in line contact (for instance, involute helical gears with parallel axes, worm gear drives with cylindrical worms, etc.) are very sensitive to angular errors of misalignment that cause edge contact and an unfavorable shape of transmission errors and vibration. The new topology of gear tooth surfaces is based on the localization of bearing contact, and the synthesis of a predesigned parabolic function of transmission errors that is able to absorb a piecewise linear function of transmission errors caused by gear misalignment. The report will describe the following topics: description of kinematics of CNC machines with six degrees of freedom that can be applied for generation of gear tooth surfaces with new topology. A new method for grinding of gear tooth surfaces by a cone surface or surface of revolution based on application of CNC machines is described. This method provides an optimal approximation of the ground surface to the given one. This method is especially beneficial when undeveloped ruled surfaces are to be ground. Execution of motions of the CNC machine is also described. The solution to this problem can be applied as well for the transfer of machine tool settings from a conventional generator to the CNC machine. The developed theory required the derivation of a modified equation of meshing based on application of the concept of space curves, space curves represented on surfaces, geodesic curvature, surface torsion, etc. Condensed information on these topics of differential geometry is provided as well.

Litvin, F. L.; Chen, N. X.

1994-04-01

124

MOST satellite photometry of stars in the M67 field: eclipsing binaries, blue stragglers and ? Scuti variables  

NASA Astrophysics Data System (ADS)

We present two series of MOST (Microvariability and Oscillations of STars) space-based photometry, covering nearly continuously 10 d in 2004 and 30 d in 2007, of selected variable stars in the upper main sequence of the old open cluster M67. New high-precision light curves were obtained for the blue straggler binary/triple systems AH Cnc, ES Cnc and EV Cnc. The precision and phase coverage of ES Cnc and EV Cnc is by far superior to any previous observations. The light curve of ES Cnc is modelled in detail, assuming two dark photospheric spots and Roche geometry. An analysis of the light curve of AH Cnc indicates a low mass ratio (q ~ 0.13) and a high inclination angle for this system. Two new long-period eclipsing binaries, GSC 814-323 and HD 75638 (non-members of M67) were discovered. We also present ground-based DDO spectroscopy of ES Cnc and of the newly found eclipsing binaries. Especially interesting is HD 75638, a member of a visual binary, which must itself be a triple or a higher multiplicity system. New light curves of two ? Scuti pulsators, EX Cnc and EW Cnc, have been analysed leading to detection of 26 and eight pulsation frequencies of high temporal stability. Based on photometric data from MOST, a Canadian Space Agency mission (jointly operated by Dynacon Inc., the University of Toronto Institute for Aerospace Studies and the University of British Columbia, with the assistance of the University of Vienna), and on spectroscopic data from the David Dunlap Observatory, University of Toronto. E-mail: pribulla@ta3.sk (TP); rucinski@astro.utoronto.ca (SR)

Pribulla, Theodor; Rucinski, Slavek; Matthews, Jaymie M.; Kallinger, Thomas; Kuschnig, Rainer; Rowe, Jason F.; Guenther, David B.; Moffat, Anthony F. J.; Sasselov, Dimitar; Walker, Gordon A. H.; Weiss, Werner W.

2008-11-01

125

Research and exploitation of CNC laser manufacturing online monitoring system based on OpenGL  

NASA Astrophysics Data System (ADS)

CNC manufacturing online monitoring technology is a significant method to improve the processing quality and achieve an important part of intelligent processing. Based on OpenGL 3D graphics technology, a Computer Numerical Control (CNC ) Laser Manufacturing 3D model is established; based on the model and the powerful ability of OpenGL, a CNC manufacturing on-line monitoring system is developed so as to achieve the ability of CNC remote real-time online monitoring in different working locations. Remote real-time online monitoring of different position of the CNC is realized. The online monitoring scope of the CNC is enlarged, with more flexibility to meet the demands of practical application, meanwhile the cost of hardware investment is greatly reduced.

Wang, Gang; Hu, Shengsun; Wang, Mingjian; Ding, Wei; Zhao, Jie

2010-12-01

126

Relative isotopic abundances of zirconium in S-type stars  

Microsoft Academic Search

The relative abundances of the six stable or nearly stable isotopes of zirconium were measured for three S stars, R Cyg, V Cnc, and R Gem. The method of analysis is described with the abundances determined by comparing the observed stellar profile of intensity vs wavelength with synthetic spectra calculated by the Minnaert interpolation scheme for a single slab LTE

A. C. Zook

1978-01-01

127

Transit of super-Earth 55 Cnc e (Demory+, 2011)  

Microsoft Academic Search

This table contains the raw photometric time series obtained after reduction of the warm Spitzer IRAC 4.5 microns data of a transit of 55 Cnc e (see paper for complete description). The first column gives the date as Heliocentric Julian Days (HJD), the second one gives the flux normalized to the out-of-eclipse average value, the third one gives the photon

B.-O. Demory; M. Gillon; D. Deming; D. Valencia; S. Seager; B. Benneke; C. Lovis; P. Cubillos; J. Harrington; K. B. Stevenson; M. Mayor; F. Pepe; D. Queloz; D. Segransan; S. Udry

2011-01-01

128

An Internet-Based Virtual CNC Milling System  

Microsoft Academic Search

This paper addresses the importance of integrating a virtual Manufacturing (VM) system with the Internet and proposes a web-based,\\u000a scalable and distributed architecture for developing a platform-independent VM system. A prototype web-based virtual CNC milling\\u000a system has been developed using Virtual Reality Modelling Language and Java. The user can easily set up machining conditions,\\u000a operate the virtual milling machine in

S. K. Ong; L. Jiang; A. Y. C. Nee

2002-01-01

129

Real-time NURBS command generators for CNC servo controllers  

Microsoft Academic Search

This study proposes a real-time Non-Uniform Rational B-Spline (NURBS) motion command generator for computer numerical control (CNC) machines to achieve the goal of high-speed and highly accurate machining. Different numerical algorithms for implementing the NURBS motion command generator are compared on the basis of both the computation time and the precision of geometric representation. In addition, to reduce the computation

M.-Y. Cheng; M.-C. Tsai; J.-C. Kuo

2002-01-01

130

Incremental sheet metal forming on CNC milling machine-tool  

Microsoft Academic Search

Incremental sheet metal forming is a promising process providing a short and inexpensive way of forming products having a relatively simple but interesting shape. The paper presents the process controlled by CNC milling machine-tool together with CAD\\/CAM Master Cam system and a smooth forming tool. With experimental testing and measurements the limits of forming without a full-size model were defined.

J. Kopac; Z. Kampus

2005-01-01

131

A Framework for an Intelligent CNC and Data Model  

Microsoft Academic Search

In this paper, we present a conceptual framework for designing and implementing an intelligent CNC system. The architecture\\u000a and functional modules are derived from requirement analysis, and they are designed to have a thinking capability before,\\u000a during, and after the execution of the manufacturing task, so that the assigned task can be effectively executed while dealing\\u000a with unexpected changes occurring

S.-H. Suh; S.-U. Cheon

2002-01-01

132

Smoothing of Time-Optimal Feedrates for Cartesian CNC Machines  

Microsoft Academic Search

\\u000a Minimum-time traversal of curved paths by Cartesian CNC machines, subject to prescribed bounds on the magnitude of acceleration\\u000a along each axis, usually involves a “bang-bang” control strategy in which the acceleration bound is realized by one or another\\u000a of the machine axes at each instant during the motion. For a path specified by a polynomial parametric curve and prescribed\\u000a acceleration

Casey L. Boyadjieff; Rida T. Farouki; Sebastian D. Timar

2005-01-01

133

CNC water-jet machining and cutting center  

Microsoft Academic Search

Computer Numerical Control (CNC) water-jet machining was investigated to determine the potential applications and cost-effectiveness that would result by establishing this capability in the engineering shops of Allied-Signal Inc., Kansas City Division (KCD). Both conductive and nonconductive samples were machined at KCD on conventional machining equipment (a three-axis conversational programmed mill and a wire electrical discharge machine) and on two

D. C. Bartlett

1991-01-01

134

The feedrate scheduling of NURBS interpolator for CNC machine tools  

Microsoft Academic Search

This paper proposes an off-line feedrate scheduling method of CNC machines constrained by chord tolerance, acceleration and jerk limitations. The off-line process for curve scanning and feedrate scheduling is realized as a pre-processor, which releases the computational burden in real-time task. The proposed method first scans a non-uniform rational B-spline (NURBS) curve and finds out the crucial points with large

An-Chen Lee; Ming-Tzong Lin; Yi-Ren Pan; Wen-Yu Lin

2011-01-01

135

VIRTUAL TRAINING ENVIRONMENT FOR A 3AXIS CNC MILLING MACHINE  

Microsoft Academic Search

A virtual training environment for a 3-axis CNC milling machine is presented. The key elements of the environment are: (a) textured 3D photo-realistic virtual models of the machines and lab; (b) machine simulator for the machines' controls and moving parts; (c) semi-empirical model of the machining operation; (d) hierarchical knowledge-base for process training; (e) unstructured knowledge-base for lecture delivery; (f)

Tamer M. Wasfy; Ayman M. Wasfy; Hazim El-Mounayri; Daniel Aw

136

Accuracy enhancement of five-axis CNC machines through real-time error compensation  

Microsoft Academic Search

Although error modeling and compensation have given significant results for three-axis CNC machine tools, a few barriers have prevented this promising technique from being applied in five-axis CNC machine tools. One crucial barrier is the difficulty of measuring or identifying link errors in the rotary block of five-axis CNC machine tools. The error model is thus not fully known. To

W. T Lei; Y. Y Hsu

2003-01-01

137

Autonomously Proficient CNC Controller for High-Performance Machine Tools Based on an Open Architecture Concept  

Microsoft Academic Search

The paper deals with the new controller for the high performance CNC machine tools. The controller proposed is referred to as “TRUE-CNC.” “TRUE” means Transparent, Transportable and Transplantable, Revivable, User-reconfigurable, and Evolving. TRUE-CNC allows the operator to achieve the maximum productivity and highest possible quality of the machined parts in a given environment with autonomous capturing of the machining operation

Kazuo Yamazaki; Yoshimaro Hanaki; Masahiko Mori; Kazusaka Tezuka

1997-01-01

138

Modeling and control of cnc machines using a PC-based open architecture controller  

Microsoft Academic Search

A PC-based open architecture computer numerical controller (CNC) is introduced to control milling machines. The controller is implemented on two systems: (1) a single-axis high speed milling machine using analog control signals where the PC-based controller assumes all CNC functions and (2) a three-axis milling machine controlled by digital signals where the existing CNC continues to monitor peripheral functions but

Stephen J. Rober; Yung C. Shin

1995-01-01

139

Rapid evaluation technology for CNC machine tool slide level based on built-in sensors  

Microsoft Academic Search

Slide level impacts the CNC machine tool performance. The deterioration of slide level will result in the torsional vibration\\u000a of a feed-axis control system and lower the CNC machine tool control precision. It is necessary to investigate the rapid evaluation\\u000a technology for the slide level of a CNC machine tool. In this paper, a new type of rapid evaluation method

Yuqing Zhou; Xuesong Mei; Gedong Jiang; Nuogang Sun

2010-01-01

140

Design and development of an open architecture CNC controller for milling machine retrofitting  

Microsoft Academic Search

Most computer numerical control (CNC) machines used in Thai industry are imported. With regular maintenance, these CNC machines could last up to 10 years. After that, the owners would either purchase a new machine or upgrade the old model; the later process is widely known as ldquoretrofitting.rdquo However, purchasing a new CNC machine is a big financial burden for small-to-medium

Kittipong Ekkachai; Udom Komin; W. Chaopramualkul; A. Tantaworrasilp; P. Kwansud; P. Seekhao; T. Leelasawassuk; K. Tanta-Ngai; K. Tungpimolrut

2009-01-01

141

Magnetic activity and evolution of Algol-type stars  

Microsoft Academic Search

We examine the possibility of tracing dynamo action in mass-losing stars that are components of Algol-type binaries. Our analysis is based on the calculation of the non-conservative evolution of a system that initially consists of a 1.65-Msolar star with a small helium core and a 0.99-Msolar main-sequence companion. We perform our calculations for the evolutionary model of S Cnc in

Marek J. Sarna; Alexander Muslimov; Sinan K. Yerli

1997-01-01

142

Design and Implementation of CNC Machine Remote Monitoring and Controlling System Based on Embedded Internet  

Microsoft Academic Search

The network control of CNC machine is the inexorable development trend of modern manufacturing industry, and the combination of embedded technology with network has become a research hot. This paper puts forward a novel design idea of remote monitoring and controlling system of CNC machine based on embedded Internet, presents its architecture principle design and software-hardware implementation procedure of the

Zhai Wen-zheng; Hu Yue-li

2010-01-01

143

Distributed Intelligent Maintenance System for CNC Machine Tools Based on Kansei Engineering  

Microsoft Academic Search

Intelligent maintenance system (IMS) is a potential selection for modern CNC machine tools. Based on the theory of Kansei engineering (K-E), a new distributed intelligent maintenance system (DIMS) has been developed for CNC machine tools. The DIMS is mainly composed of expert base, engineer station, K-E operator, concrete processes or conditions, and communication connections. The DIMS has an excellent merit

Yang Yong; Wen Shan

2009-01-01

144

CNC incremental sheet forming of an axially symmetric specimen and the locus of optimization  

Microsoft Academic Search

CNC incremental sheet forming is a new flexible sheet forming process. It does not need a dedicated die and can form sheet parts with a higher forming limit and of complicated shape by use of a CNC device. This process is suited to the forming of sheet parts of small volume, diversification and complicated shape in space-flight, automobile and civil

Kun Dai; Z. R Wang; Yi Fang

2000-01-01

145

Prediction of surface roughness in CNC face milling using neural networks and Taguchi's design of experiments  

Microsoft Academic Search

In this paper, a neural network modeling approach is presented for the prediction of surface roughness (Ra) in CNC face milling. The data used for the training and checking of the networks’ performance derived from experiments conducted on a CNC milling machine according to the principles of Taguchi design of experiments (DoE) method. The factors considered in the experiment were

P. G Benardos; G. C Vosniakos

2002-01-01

146

FPGA based acceleration and deceleration circuit for industrial robots and CNC machine tools  

Microsoft Academic Search

In order to make industrial robots and computer numerical control (CNC) machine tools perform tasks efficiently, many techniques for the acceleration and deceleration of industrial robots and CNC machine tools have been proposed. Polynomial technique can generate velocity profiles of various acceleration and deceleration characteristics, but it requires a lot of computations. Digital convolution technique can generate efficiently velocity profiles,

Jae Wook Jeon; Yun-Ki Kim

2002-01-01

147

A generalized approach for the acceleration and deceleration of industrial robots and CNC machine tools  

Microsoft Academic Search

Many techniques for the acceleration and deceleration of industrial robots and computer numerical control (CNC) machine tools have been proposed in order to make industrial robots and CNC machine tools perform given tasks efficiently. Although the techniques selecting polynomial functions can generate various acceleration and deceleration characteristics, the major problem is the computational load. The digital convolution techniques are more

Jae Wook Jeon; Young Youl Ha

2000-01-01

148

The prevention and the cure, improvement measures of noise and vibration in hydraulic system of CNC machine tool  

Microsoft Academic Search

The noise and the vibration produced from hydraulic system of CNC machine tool seriously affect the normal use of CNC machine tool. The noise and the vibration are relatively complex problem in the diagnosis and elimination of CNC machine tool hydraulic technical failure. It is an effective way of replace the old-fashioned hydraulic pump with new type. the correct installation

Wanghong Ying; Penger Bao

2010-01-01

149

Implementation of CAD/CAM/CNC Curriculum Using Mastercam X Software in Technical Programs  

NSDL National Science Digital Library

One of the major contributions to the growing acceptance of Computer Numerical Control (CNC) has been the development of Computer Aided Manufacturing (CAM). A Computer Aided Manufacturing (CAM) program uses a CAD drawing, and then adds the cutting parameters to generate the CNC program. MastercamX is PC-based CAD/CAM software, which integrates the geometry, toolpath, and the G-code program together. The CAD section of the Mastercam software generates a dimensioned drawing using basic entities. The geometry file is saved as a CAD file and then turned into CNC code. The CNC code is used to machine parts on a milling machine. Mastercam software ties the CAD/CAM process together to generate a CNC program to make a part, using a machine tool.

Heidari, Farzin

2009-09-25

150

Transit of super-Earth 55 Cnc e (Demory+, 2011)  

NASA Astrophysics Data System (ADS)

This table contains the raw photometric time series obtained after reduction of the warm Spitzer IRAC 4.5 microns data of a transit of 55 Cnc e (see paper for complete description). The first column gives the date as Heliocentric Julian Days (HJD), the second one gives the flux normalized to the out-of-eclipse average value, the third one gives the photon noise for each measurement and the fourth and fifth ones are the stellar centroid position in x and y on the array. (1 data file).

Demory, B.-O.; Gillon, M.; Deming, D.; Valencia, D.; Seager, S.; Benneke, B.; Lovis, C.; Cubillos, P.; Harrington, J.; Stevenson, K. B.; Mayor, M.; Pepe, F.; Queloz, D.; Segransan, D.; Udry, S.

2011-08-01

151

3D simulations of RS Ophiuchi: from accretion to nova blast  

Microsoft Academic Search

Context: The binary star system RS Ophiuchi is a recurrent nova, with outbursts occurring about every 22 years. It consists of a red giant star (RG) and a wind accreting white dwarf close to the Chandrasekhar limit. This system is considered a prime candidate for evolving into an SNIa. For its most recent outbursts in 1985 and 2006, exquisite multiwavelength

R. Walder; D. Folini; S. N. Shore

2008-01-01

152

Time-resolved Spectroscopy of RS Canum Venaticorum Short-Period Systems. II. RT Andromedae, WY Cancri, and XY Ursae Majoris  

NASA Astrophysics Data System (ADS)

We present the second part of the results of our spectroscopic study of orbital phase resolution of short-period active binaries. In this paper we present the observations of the binaries RT And, WY Cnc, and XY UMa, for which we obtained simultaneous low-resolution spectra in the H?, H?, and Ca II infrared triplet (IRT; 8498 and 8542 Å) lines, and higher resolution spectra in H? for WY Cnc and XY UMa. H? and H? emission excess was found in all the observed orbital phases of WY Cnc and XY UMa, while RT And showed H? emission only during some orbital phases. We measure a clear Ca II (IRT) excess in all the spectra of the three binaries. The ratio of the flux excesses derived for these binaries, E_H?/E_H?~= 1-3 and E_8542/E_8498~= 1-3, give low values typical of solar plage structures. In the higher resolution H? spectra, we found emissions that can be associated with both stellar components of XY UMa and WY Cnc, indicating that the faint secondary stars in both binaries are active late-type dwarfs. Some H? emission components, which could originate in extended structures between the stars, were detected in both systems.

Arévalo, M. J.; Lázaro, C.

1999-08-01

153

CNC water-jet machining and cutting center  

NASA Astrophysics Data System (ADS)

Computer Numerical Control (CNC) water-jet machining was investigated to determine the potential applications and cost-effectiveness that would result by establishing this capability in the engineering shops of Allied-Signal Inc., Kansas City Division (KCD). Both conductive and nonconductive samples were machined at KCD on conventional machining equipment (a three-axis conversational programmed mill and a wire electrical discharge machine) and on two current-technology water-jet machines at outside vendors. These samples were then inspected, photographed, and evaluated. The current-technology water-jet machines were not as accurate as the conventional equipment. The resolution of the water-jet equipment was only +/- 0.005 inch, as compared to +/- 0.0002 inch for the conventional equipment. The principal use for CNC water-jet machining would be as follows: Contouring to near finished shape those items made from 300 and 400 series stainless steels, titanium, Inconel, aluminum, glass, or any material whose fabrication tolerance is less than the machine resolution of +/- 0.005 inch; and contouring to finished shape those items made from Kevlar, rubber, fiberglass, foam, aluminum, or any material whose fabrication specifications allow the use of a machine with +/- 0.005 inch tolerance. Additional applications are possible because there is minimal force generated on the material being cut and because the water-jet cuts without generating dust.

Bartlett, D. C.

1991-09-01

154

CNC water-jet machining and cutting center  

SciTech Connect

CNC water-jet machining was investigated to determine the potential applications and cost-effectiveness that would result by establishing this capability in the engineering shops of Allied-Signal Inc., Kansas City Division (KCD). Both conductive and nonconductive samples were machined at KCD on conventional machining equipment (a three-axis conversational programmed mill and a wire electrical discharge machine) and on two current-technology water-jet machines at outside vendors. These samples were then inspected, photographed, and evaluated. The current-technology water-jet machines were not as accurate as the conventional equipment. The resolution of the water-jet equipment was only {plus minus}0.005 inch, as compared to {plus minus}0.0002 inch for the conventional equipment. The principal use for CNC water-jet machining would be as follows: Contouring to near finished shape those items made from 300 and 400 series stainless steels, titanium, Inconel, aluminum, glass, or any material whose fabrication tolerance is less than the machine resolution of {plus minus}0.005 inch; and contouring to finished shape those items made from Kevlar, rubber, fiberglass, foam, aluminum, or any material whose fabrication specifications allow the use of a machine with {plus minus}0.005 inch tolerance. Additional applications are possible because there is minimal force generated on the material being cut and because the water-jet cuts without generating dust. 12 figs.

Bartlett, D.C.

1991-09-01

155

Spectral parameters of quiescent state coronae of RS CVn binaries  

NASA Astrophysics Data System (ADS)

We present analyses of quiescent state coronae of RS CVn-type binaries observed with XMM-Newton observatory. The quiescent state X-ray luminosities in the energy band of 0.3-10.0 keV of these star were found to be 10^{30-32} erg s^{-1}. Most of the stars were found to have three temperatures coronal plasma. The median value of hottest coronal temperature of these stars was found to be 2.92 keV. However, the coolest temperatures were near the 0.38 keV and 0.99 keV, respectively. The median value of global abundances of quiescent state coronae of these stars were found to be 0.14 times solar photospheric value.

Pandey, J. C.; Pant, Vaibhav

156

A study of coronal abundances in RS CVn binaries%  

Microsoft Academic Search

We present XMM-Newton data of several RS CVn binary systems. High-resolution X-ray spectra obtained with the Reflection Grating Spectrometers have been interpreted simultaneously with the European Photon Imaging Camera spectra. Highly active stars show a depletion of elements with a low first ionization potential (FIP) relative to high-FIP elements, whereas intermediately active binaries show either no FIP bias or a

M. Audard; M. Güdel; A. Sres; A. J. J. Raassen; R. Mewe

2003-01-01

157

Prepolishing on a CNC platform with bound abrasive contour tools  

NASA Astrophysics Data System (ADS)

Deterministic microgrinding (DMG) of optical glasses and ceramics is the commercial manufacturing process of choice to shape glass surfaces prior to final finishing. This process employs rigid bound matrix diamond tooling resulting in surface roughness values of 3-5?m peak to valley and 100-400nm rms, as well as mid-spatial frequency tool marks that require subsequent removal in secondary finishing steps. The ability to pre-polish optical surfaces within the grinding platform would reduce final finishing process times. Bound abrasive contour wheels containing cerium oxide, alumina or zirconia abrasives were constructed with an epoxy matrix. The effects of abrasive type, composition, and erosion promoters were examined for tool hardness (Shore D), and tested with commercial optical glasses in an Optipro CNC grinding platform. Metrology protocols were developed to examine tool wear and subsequent surface roughness. Work is directed to demonstrating effective material removal, improved surface roughness and cutter mark removal.

Schoeffler, Adrienne E.; Gregg, Leslie L.; Schoen, John M.; Fess, Edward M.; Hakiel, Michael; Jacobs, Stephen D.

2003-05-01

158

Design and performance of a small precision CNC turning machine  

SciTech Connect

This paper describes the design of a CNC turning machine that is capable of machining workpieces up to 100 mm in diameter with a high contour accuracy and a very low surface roughness. Two nearly identical machines have been built and put into operation using this design, one for serial parts manufacture and the other for research into improving the accuracy of single-point machining; information based on this operational experience is also presented. The first machine has demonstrated an accuracy of 0.1 ..mu..m peak-to-valley on contoured workpieces, while the second machine has produced surface roughnesses of 1 nm rms in flat facing of electroless nickel with a diamond tool.

Donaldson, R.R.; Thompson, D.C.

1986-02-26

159

Springback behaviour in bending of ultra-high-strength steel sheets using CNC servo press  

Microsoft Academic Search

The springback behaviour of ultra-high-strength steel sheets in bending was investigated under controlled conditions using a CNC servo press. Although the ultra-high-strength steel sheets are attractive in reducing weight of cars, the amount of springback of the ultra-high-strength steel sheets in the forming is very large due to high strength. The CNC servo press has the function of accurately controlling

K. Mori; K. Akita; Y. Abe

2007-01-01

160

An investigation of stick-slip friction on the contouring accuracy of cnc machine tools  

Microsoft Academic Search

Stick-slip friction has a great influence on the contouring accuracy of CNC machine tools. In this paper, a nonlinear model is used to simulate and analyze dynamic behaviors of stick-slip friction on the contouring accuracy of CNC machine tools. A simple control strategy is then developed to tune the control loop gain for reducing the contouring error due to stick-slip

Y. S. Tarng; H. E. Cheng

1995-01-01

161

Identification of common sensory features for the control of CNC milling operations under varying cutting conditions  

Microsoft Academic Search

The main focus of this study is to identify the most influential and common sensory features for the process quality characteristics in CNC milling operations—dimensional accuracy (bore size tolerance) and surface roughness—using three different material types (6061-T6 aluminum, 7075-T6 aluminum, and ANSI-4140 steel). The materials were machined on a vertical CNC mill, retrofitted with multiple sensors and data acquisition systems,

Yalcin M. Ertekin; Yongjin Kwon

2003-01-01

162

Control of Drosophila head segment identity by the bZIP homeotic gene cnc.  

PubMed

Mutational analysis of cap'n'collar (cnc), a bZIP transcription factor closely related to the mammalian erythroid factor NF-E2 (p45), indicates that it acts as a segment-specific selector gene controlling the identity of two cephalic segments. In the mandibular segment, cnc has a classical homeotic effect: mandibular structures are missing in cnc mutant larvae and replaced with duplicate maxillary structures. We propose that cnc functions in combination with the homeotic gene Deformed to specify mandibular development. Labral structures are also missing in cnc mutant larvae, where a distinct labral primordia is not properly maintained in the developing foregut, as observed by the failure to maintain and elaborate patterns of labral-specific segment polarity gene expression. Instead, the labral primordium fuses with the esophageal primordium to contribute to formation of the esophagus. The role of cnc in labral development is reciprocal to the role of homeotic gene forkhead, which has an identical function in the maintenance of the esophageal primordium. This role of homeotic selector genes for the segment-specific maintenance of segment polarity gene expression is a unique feature of segmentation in the preoral head region of Drosophila. PMID:7867505

Mohler, J; Mahaffey, J W; Deutsch, E; Vani, K

1995-01-01

163

Integration and diversity of the regulatory network composed of Maf and CNC families of transcription factors.  

PubMed

Recent progress in the analysis of transcriptional regulation has revealed the presence of an exquisite functional network comprising the Maf and Cap 'n' collar (CNC) families of regulatory proteins, many of which have been isolated. Among Maf factors, large Maf proteins are important in the regulation of embryonic development and cell differentiation, whereas small Maf proteins serve as obligatory heterodimeric partner molecules for members of the CNC family. Both Maf homodimers and CNC-small Maf heterodimers bind to the Maf recognition element (MARE). Since the MARE contains a consensus TRE sequence recognized by AP-1, Jun and Fos family members may act to compete or interfere with the function of CNC-small Maf heterodimers. Overall then, the quantitative balance of transcription factors interacting with the MARE determines its transcriptional activity. Many putative MARE-dependent target genes such as those induced by antioxidants and oxidative stress are under concerted regulation by the CNC family member Nrf2, as clearly proven by mouse germline mutagenesis. Since these genes represent a vital aspect of the cellular defense mechanism against oxidative stress, Nrf2-null mutant mice are highly sensitive to xenobiotic and oxidative insults. Deciphering the molecular basis of the regulatory network composed of Maf and CNC families of transcription factors will undoubtedly lead to a new paradigm for the cooperative function of transcription factors. PMID:12234662

Motohashi, Hozumi; O'Connor, Tania; Katsuoka, Fumiki; Engel, James Douglas; Yamamoto, Masayuki

2002-07-10

164

Spectrophotometry of carbon stars. II  

SciTech Connect

This paper presents the color temperatures of 52 carbon stars which have been determined by means of the monochromatic color indices delta-m (5710, 6680) for the corresponding spectral range. Comparison of the T/sub c/ for stars of the spectral classes R and N shows that for the former there is a definite dependence of the R subclass on the temperature. For the latter, this is not observed. When the C classification is considered, it is found to be in the case of the later types. It is assumed that U Cam, T Cnc, RY Dra, T Lyr, W Ori, V CrB and SS Vir may be surrounded by circumstellar dust envelopes whose masses and densities may vary with the time.

Organesyan, R.K.; Nersisyan, S.E.

1986-03-01

165

Emisión H? en sistemas binarios cromosféricamente activos (RS CVn y BY Dra)  

NASA Astrophysics Data System (ADS)

We report here high and medium resolution Balmer H? line profiles for 11 chromospherically active binary systems including the class of RS Canum Venaticorum binaries (RS CVn) and BY Draconis (BY Dra) with a total range of rotation periods from 0.8 to 24 days. We have obtained different types of H? line profiles: strong emission line, weak emission line with strong superposed absorption profile and filled-in absorption line profile. We have measured the H? equivalent width of the program stars and the H? core emission was determined by subtraction of the equivalent width of a presumably inactive star with the same spectral type and luminosity class.

Fernández-Figueroa, M. J.; Montes, D.; de Castro, E.

1992-05-01

166

Spatial augmented reality on industrial CNC-machines  

NASA Astrophysics Data System (ADS)

In this work we present how Augmented Reality (AR) can be used to create an intimate integration of process data with the workspace of an industrial CNC (computer numerical control) machine. AR allows us to combine interactive computer graphics with real objects in a physical environment - in this case, the workspace of an industrial lathe. ASTOR is an autostereoscopic optical see-through spatial AR system, which provides real-time 3D visual feedback without the need for user-worn equipment, such as head-mounted displays or sensors for tracking. The use of a transparent holographic optical element, overlaid onto the safety glass, allows the system to simultaneously provide bright imagery and clear visibility of the tool and workpiece. The system makes it possible to enhance visibility of occluded tools as well as to visualize real-time data from the process in the 3D space. The graphics are geometrically registered with the workspace and provide an intuitive representation of the process, amplifying the user's understanding and simplifying machine operation.

Olwal, Alex; Gustafsson, Jonny; Lindfors, Christoffer

2008-02-01

167

The design of an ultra-precision CNC measuring machine  

SciTech Connect

A specialized ultra-precision CNC measuring machine is being developed to provide an inspection capability compatible with existing precision turning machines. The instrument is to be applied to the inspection of the inner and outer surfaces of hemispherical shells and other axisymmetric parts, with diameters of up to 400 mm. The overall accuracy of the machine operating in continuous path contouring mode is to be less than 0.75 micrometre (p-v) per surface, including both instrument and process-related errors. In addition, an accuracy of 1.75 micrometres is required for the inspection of wall thickness on some categories of parts, which in some instances may be distorted by gravity loading. This latter requirement dictates a single setup for the inspection of inner and outer surfaces, and effectively eliminates a standard Coordinate Measuring Machine (CMM) configuration for the new gauge. The new instrument is known as the Certification of Process (COP) Gauge. 9 refs., 5 figs., 2 tabs.

Thompson, D.C.

1989-01-01

168

Stellar surface phenomena: a spectroscopic study of the RS Canum Venaticorum binaries  

SciTech Connect

High resolution observations are reported of the Ca II H and K and H..cap alpha.. regions in a selection of twenty-five RS CVn and related Ca II emission objects. The RS CVn stars were found to have Ca II H and K and H..cap alpha.. line surface fluxes and chromospheric loss rates over an order of magnitude larger than standard stars for their respective spectral types and luminosity classes. In the short-period systems, these line surface fluxes and chromospheric loss rates were found to be well correlated with the fraction of the Roche lobe filled by the active star in the system and the separation between the stars. The H..cap alpha.. profiles of all of the RS CVn systems were found to be filled in by the presence of an overlying emission at all epochs; the profiles of several systems were found to be variable. Combining results of the Ca II and H..cap alpha.. observations, the chromospheric temperature structure in the lower chromosphere was mapped. The RS CVn stars were found to have steeper than normal chromospheric temperature gradients, in agreement with the predictions of the chromospheric models of Linksy and his collaborators. Several systems were also found which showed Ca II H and K emission but not H..cap alpha.. emission.

Smith, S.E.

1984-01-01

169

CAM/CNC. Computer-Aided Machining and Computer Numerically Controlled Machines. Edition 1.1. An NCMS Technology Deployment Document.  

National Technical Information Service (NTIS)

Computer-aided machining (CAM) defines and creates the program that derives a CNC machine. CAM/CNC uses a computer to control the machining sequence of a machine tool, offering considerable benefits over manually controlled machine tools. Faster productio...

D. R. Arnsdorf

1990-01-01

170

Documentation for the machine-readable version of the Catalogue of Nearby Stars, edition 1969  

NASA Astrophysics Data System (ADS)

The Catalogue of Nearby Stars, Edition 1969 (Gliese 1969) contains a number of modifications and additions to the 1957 catalog. It should be mentioned that the 1969 edition lists: (1) all 915 stars of the first edition, even though newer parallaxes place some of the stars below the catalog limit; (2) almost all known stars having trigonometric parallaxes or = 0.045 deg, although in some cases the mean values of trigonometric and spectral or photometric parallaxes are or = 0.045 deg. Pleiades stars and the carbon star X Cnc have been omitted; and (3) all stars with mean (resulting) parallaxes or = 0.045 deg. The resulting catalog contains 1529 single stars and systems with a total of 1890 components (not including spectroscopic and astrometric companions). The machine-readable version of the catalog is described. It is intended to enable users to read and process the data without problems or guesswork.

Warren, W. H., Jr.

1982-10-01

171

H. cap alpha. in RS CVn binaries  

SciTech Connect

The 1976--78 results of a spectroscopic program to monitor H..cap alpha.. in several RS CVn-type binaries are reported. For six objects well observed over orbital phase, four (HR 4665, HR 5110, sigma Gem, Z Her) show H..cap alpha.. as an absorption feature having a constant ( +- 15%) equivalent width (EW). AR Lac exhibits an absorption profile also, but the EW varies by a factor of three due to partial filling by emission. This variation is sporadic and not phase dependent. The H..cap alpha.. feature in HK Lac shows the most extreme variation: normally seen as an absorption feature with variable EW, it has been observed as a pure emission feature on three spectrograms, showing a blueshift with respect to the photosphere of approx.50--100 km sec/sup -1/. On a single occasion HK Lac showed double H..cap alpha.. emission with a separation of the peaks of approx.300 km sec/sup -1/. These high velocity features are interpreted in terms of prominence-like structure in the atmosphere of the active star.

Bopp, B.W.; Talcott, J.C.

1980-01-01

172

The study of opened CNC system of turning-grinding composite machine tool based on UMAC  

NASA Astrophysics Data System (ADS)

The general function analysis of a turning-grinding composite machine tool (TGCM) is done. The structure of the TGCM based on 'process integration with one setup' theory in this paper is presented. The CNC system functions of TGCM are analyzed and the CNC framework of TGCM is discussed. Finally the opened-CNC system for this machine tool is developed based on UMAC (Universal Motion and Automation Controller) included hardware system and software system. The hardware structure layout is put forward and the software system is implemented by using VC++6.0. The hardware system was composed of IPC and UMAC. The general control system meets the requirement of integrity machining and matches the hardware structure system of TGCM. The practical machining experiment results showed that the system is valid with high accuracy and high reliability.

Wang, Hongjun; Han, Qiushi; Wu, Guoxin; Ma, Chao

2010-12-01

173

An iterative learning control method with application for CNC machine tools  

SciTech Connect

A proportional, integral, and derivative (PID) type iterative learning controller is proposed for precise tracking control of industrial robots and computer numerical controller (CNC) machine tools performing repetitive tasks. The convergence of the output error by the proposed learning controller is guaranteed under a certain condition even when the system parameters are not known exactly and unknown external disturbances exist. As the proposed learning controller is repeatedly applied to the industrial robot or the CNC machine tool with the path-dependent repetitive task, the distance difference between the desired path and the actual tracked or machined path, which is one of the most significant factors in the evaluation of control performance, is progressively reduced. The experimental results demonstrate that the proposed learning controller can improve machining accuracy when the CNC machine tool performs repetitive machining tasks.

Kim, D.I.; Kim, S. [Samsung Electronics, Suwon (Korea, Republic of)

1996-01-01

174

Coronae of rapidly rotating star. V. The other stars  

SciTech Connect

Results of Einstein X-ray observations of 25 stellar systems are presented. The systems observed include 15 spectroscopic binaries of which eleven were detected; nine were serendipitous detections, three of which may be new RS CVn systems. Coronal activity levels and their implications for these stars are discussed. 39 references.

Walter, F.M.

1985-07-01

175

THREE-DIMENSIONAL DOPPLER TOMOGRAPHY OF THE RS VULPECULAE INTERACTING BINARY  

SciTech Connect

Three-dimensional Doppler tomography has been used to study the H{alpha} emission sources in the RS Vulpeculae (RS Vul) interacting binary. The two-dimensional tomogram of this binary suggested that most of the emission arises from the cool mass losing star with additional evidence of a gas stream flowing close to its predicted trajectory. However, the three-dimensional tomogram revealed surprising evidence that the gas stream has an average velocity of -85 km s{sup -1} relative to the central velocity plane at V{sub z} = 0 km s{sup -1}, unlike U CrB in which the stream was prominent along this central plane. These unexpected V{sub z} motions may result from the interaction between magnetic activity on the cool star and the gravitationally induced Roche lobe overflow from that star. Evidence of a loop prominence on the cool star close to the L1 point has been found in the three-dimensional tomogram of RS Vul; hence, the magnetic field lines may have deflected the gas stream relative to the central plane. This result is consistent with earlier detections of RS Vul as both an X-ray and a radio source, and represents the first detection of a loop prominence in an interacting binary based on tomography. Moreover, recent radio images of {beta} Per, the prototype of the Algols, show that the magnetic field of the mass losing star is asymmetric and extends well beyond the orbital plane of the binary, so it is now plausible that the gas flow between the stars in RS Vul could be deflected in an asymmetric way by the magnetic field.

Richards, Mercedes T. [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Sharova, Olga I.; Agafonov, Michail I., E-mail: mrichards@astro.psu.ed, E-mail: shol@nirfi.sci-nnov.r, E-mail: agfn@nirfi.sci-nnov.r [Radiophysical Research Institute (NIRFI), 25/12a, Bolshaya Pecherskaya St., Nizhny Novgorod 603950 (Russian Federation)

2010-09-10

176

Physical Parameters of the Overcontact Binary AH Cnc in the Old Open Cluster M 67  

NASA Astrophysics Data System (ADS)

We present a photometric study of the overcontact binary AH Cnc. The CCD observations were done with the Russian-Turkish 1.5 m telescope and the light-curve was solved with the Wilson-Devinney code. The physical parameters of the components have been deduced as M1 = 1.22 Msun, M2 = 0.20 Msun, R1 = 1.37 Rsun, R2 = 0.66 Rsun, L1 = 2.65 Lsun and L2 = 0.63 Lsun from the obtained orbital parameters and the distance modules of M 67. AH Cnc has been compared with similar systems in the Hertzsprung-Russell diagram.

Yakut, K.; Aerts, C.

2006-04-01

177

H I OBSERVATIONS OF THE ASYMPTOTIC GIANT BRANCH STAR X HERCULIS: DISCOVERY OF AN EXTENDED CIRCUMSTELLAR WAKE SUPERPOSED ON A COMPACT HIGH-VELOCITY CLOUD  

SciTech Connect

We report H I 21 cm line observations of the asymptotic giant branch (AGB) star X Her obtained with the Robert C. Byrd Green Bank Telescope (GBT) and the Very Large Array. We have unambiguously detected H I emission associated with the circumstellar envelope of the star, with a mass totaling M{sub HI} {approx} 2.1 x 10{sup -3} M{sub sun}. The H I distribution exhibits a head-tail morphology, similar to those previously observed around the AGB stars Mira and RS Cnc. The tail is elongated along the direction of the star's space motion, with a total extent of {approx}> 6.'0 (0.24 pc) in the plane of the sky. We also detect a systematic radial velocity gradient of {approx}6.5 km s{sup -1} across the H I envelope. These results are consistent with the H I emission tracing a turbulent wake that arises from the motion of a mass-losing star through the interstellar medium (ISM). GBT mapping of a 2{sup 0} x 2{sup 0} region around X Her reveals that the star lies (in projection) near the periphery of a much larger H I cloud that also exhibits signatures of interaction with the ISM. The properties of the cloud are consistent with those of compact high-velocity clouds. Using {sup 12}CO J = 1-0 observations, we have placed an upper limit on its molecular gas content of N{sub H2} < 1.3 x 10{sup 20} cm{sup -2}. Although the distance to the cloud is poorly constrained, the probability of a chance coincidence in position, velocity, and apparent position angle of space motion between X Her and the cloud is extremely small, suggesting a possible physical association. However, the large H I mass of the cloud ({approx}>2.4 M{sub sun}) and the blueshift of its mean velocity relative to X Her are inconsistent with an origin tied directly to ejection from the star.

Matthews, L. D.; Johnson, M. C. [MIT Haystack Observatory, Off Route 40, Westford, MA 01886 (United States); Libert, Y. [IRAM, 300 Rue de la Piscine, Domaine Universitaire, 38406 Saint Martin d'Heres (France); Gerard, E. [GEPI, UMR 8111, Observatoire de Paris, 5 Place J Janssen, F-92195 Meudon Cedex (France); Le Bertre, T. [LERMA, UMR 8112, Observatoire de Paris, 61 av. de l'Observatoire, F-75014 Paris (France); Dame, T. M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-42, Cambridge, MA 02138 (United States)

2011-02-15

178

Activity, rotation and evolution of the RS CVn system lambda Andromedae  

Microsoft Academic Search

With very high resolution and high S\\/N spectra as well as multicolour photometric light curves, we have studied the activity, rotation and evolution of the RS CVn system lambda And (HD 222107). Maximum entropy modelling of Johnson BV light curves tells us that two spots are present on the star around epoch 1991.5. One spot is large and rather stable,

J.-F. Donati; G. W. Henry; D. S. Hall

1995-01-01

179

X-ray spectra and the rotation-activity connection of RS Canum Venaticorum binaries  

NASA Astrophysics Data System (ADS)

Results are presented from a survey of RS CVn binaries which were observed with the imaging proportional counter (IPC) on board the Einstein Observatory. Spectral analyses of the IPC pulse height spectra show that the coronae of RS CVn binaries always contain hot gas with temperatures in excess of 10 to the 7th K, similar to active late-type main-sequence stars, and that at least two temperature components are necessary to account for the higher quality IPC spectra (when absorption is unimportant). It is argued that these bimodal temperature distributions found by the IPC are indicative of true distributions of emission measure versus temperature that are continuous (just as is the case of magnetically confined coronal plasma loops observed on the sun). It is further shown that none of the derivable X-ray characteristics of RS CVn binaries depend on rotation period, implying that previous claims of period-activity relationships in RS CVn binaries were unfounded.

Majer, P.; Schmitt, J. H. M. M.; Golub, L.; Harnden, F. R., Jr.; Rosner, R.

1986-01-01

180

Manufacturing linear and circular contours using CNC EDM and frame type tools  

Microsoft Academic Search

In traditional electro discharge machining (EDM) the usual practice is to form a 3D female cavity in the work piece by making a corresponding male shaped tool and plunging this into the work piece. Recently, however, computer numerical control (CNC) EDM machines have become available which have the potential to generate a detailed shape without using complex electrodes. This paper

M. Bayramoglu; A. W. Duffill

1995-01-01

181

The Open Architecture CNC System Based on 6-axis Flame Pipe Cutting Machine  

Microsoft Academic Search

Pipe Cutting machine has been widely used in ocean engineering, pipeline engineering, etc. According to the application of pipe cutting machine in the construction of offshore platform, a novel open architecture CNC system based on Industrial Personal Computer (IPC) and Digital motion controller (DMC) applied in a 6-axis flame Pipe Cutting machine is designed. Software system with multifunction and high

Qin Yuanfei; Xiao Juliang; Wang Gang

2011-01-01

182

A study of backlash on the motion accuracy of CNC lathes  

Microsoft Academic Search

In this paper, an analytical solution is reported to explain the experimentally observed backlash behaviors on the motion accuracy of CNC lathes. It is found that backlash occurs when the feed direction is reversed. Due to the imperfect transient response of the driving mechanism, not only the static backlash error but also the dynamic backlash error is generated on the

J. Y. Kao; Z. M. Yeh; Y. S. Tarng; Y. S. Lin

1996-01-01

183

Computer Simulation for the Study of CNC Feed Drives Dynamic Behavior and Accuracy  

Microsoft Academic Search

In the application of CNC feed drives it is desirable to predict the servo performance. By using computer simulation techniques it is possible to construct an accurate model of the servo drive. This simulation procedure makes it possible to anticipate machine design problems and correct them. This paper deals with a model of a feed drive, which consists of a

Radu E. Breaz; Octavian C. Bologa; V. S. Oleksik; G. S. Racz

2007-01-01

184

Statistical optimization and assessment of a thermal error model for CNC machine tools  

Microsoft Academic Search

The objective of a thermal error compensation system for CNC machine tools is improved machining accuracy through real time error compensation. The compensation capability depends on the accuracy of the thermal error model. A thermal error model can be obtained using an appropriate combination of temperature variables. In this study, the thermal error modeling is based on a correlation grouping

Jin-Hyeon Lee; Seung-Han Yang

2002-01-01

185

An iterative learning control method with application for CNC machine tools  

Microsoft Academic Search

A proportional, integral, and derivative (PID) type iterative learning controller is proposed for precise tracking control of industrial robots and computer numerical controller (CNC) machine tools performing repetitive tasks. The convergence of the output error by the proposed learning controller is guaranteed under a certain condition even when the system parameters are not known exactly and unknown external disturbances exist.

Dong-Il Kim; Sungkwun Kim

1996-01-01

186

Computer-aided accuracy enhancement for multi-axis CNC machine tool  

Microsoft Academic Search

A computer-aided error compensation scheme has been developed to enhance the accuracy of multi-axis CNC machine tools by compensating for machine geometric and thermal errors in software way. Stationary geometric errors including the coupling effect of linkage errors between machine slides are calibrated off line. Dynamic thermal errors are predicted on line by an artificial neural network model. Because machine

Jenq-Shyong Chen

1995-01-01

187

Integration and diversity of the regulatory network composed of Maf and CNC families of transcription factors  

Microsoft Academic Search

Recent progress in the analysis of transcriptional regulation has revealed the presence of an exquisite functional network comprising the Maf and Cap ’n’ collar (CNC) families of regulatory proteins, many of which have been isolated. Among Maf factors, large Maf proteins are important in the regulation of embryonic development and cell differentiation, whereas small Maf proteins serve as obligatory heterodimeric

Hozumi Motohashi; Tania O'Connor; Fumiki Katsuoka; James Douglas Engel; Masayuki Yamamoto

2002-01-01

188

Development of a high-speed CNC cutting machine using linear motors  

Microsoft Academic Search

The traditional approach to construct CNC machine tools has been to use rotary drive motors and ballscrews to achieve table motion. Linear motors offer several advantages over this approach, including low inertia, better performance, increased accuracy and reduced complexity. This article describes how a low cost, high-speed cutting machine was built using linear motors in order to conduct machining tests

Seamus Gordon; Michael T. Hillery

2005-01-01

189

Frame based system combination and a comparison with weighted ROVER and CNC  

Microsoft Academic Search

In this paper we present a novel ASR system combination technique able to combine systems producing word graphs of dif- ferent structure and with different segmentations. The new method is based on the definition of a time frame-wise word error cost function in a minimum Bayes risk framework. In contrast to confusion network combination (CNC), it preserves both the word

Björn Hoffmeister; Tobias Klein; Ralf Schlüter; Hermann Ney

2006-01-01

190

High speed CNC system design. Part II: modeling and identification of feed drives  

Microsoft Academic Search

Accurate modeling and identification of the feed drives' dynamics is an important step in designing a high performance CNC. This paper presents a method for identifying the dynamic parameters, as well as the friction characteristics of machine tool drives. The inertia and viscous friction are estimated through an unbiased least squares scheme. The friction model is developed by observing the

Kaan Erkorkmaz; Yusuf Altintas

2001-01-01

191

Basic CNC Operation. Training Workbook [and] Assessment and Training Guide [and] Hands-on Assessment.  

ERIC Educational Resources Information Center

This workbook is intended for students taking a course in basic computer numerical control (CNC) operation that was developed during a project to retrain defense industry workers at risk of job loss or dislocation because of conversion of the defense industry. The workbook contains daily training guides for each of the course's 13 sessions. Among…

Anoka-Hennepin Technical Coll., Minneapolis, MN.

192

A new type of machine control system to replace traditional CNC  

Microsoft Academic Search

This paper discusses the rationale behind a new form of machine tool control system which has been developed at the Key Centre for Computer Integrated Manufacture (CIM Centre) in Melbourne Australia. The new control system is based upon standard computer hardware and is intended as a replacement for computer numerical control (CNC), which has severe limitations in the CIM environment.

Andrew M. Luscombe; Dario J. Toncich; William Thompson; Richard Dluzniak

1994-01-01

193

Technical and Symbolic Knowledge in CNC Machining: A Study of Technical Workers of Different Backgrounds.  

ERIC Educational Resources Information Center

Performances of 45 individuals with varying degrees of formal and informal training in machining and programming were compared on tasks designed to tap intellectual changes that may occur with the introduction of computer numerical control (CNC). Participants--30 machinists, 8 machine operators, and 7 engineers--were asked background questions and…

Martin, Laura M. W.; Beach, King

194

CNC Turning Center Operations and Prove Out. Computer Numerical Control Operator/Programmer. 444-334.  

ERIC Educational Resources Information Center

This student guide provides materials for a course designed to instruct the student in the recommended procedures used when setting up tooling and verifying part programs for a two-axis computer numerical control (CNC) turning center. The course consists of seven units. Unit 1 discusses course content and reviews and demonstrates set-up procedures…

Skowronski, Steven D.

195

A comprehensive method for calibration of volumetric positioning accuracy of CNC-machines  

Microsoft Academic Search

A comprehensive method for measuring the systematic errors of CNC-machine tools has been studied. The method used for measurement and calibration of machine tool errors should be general and efficient. The objectives of this study include:1.Volumetric error modelling.2.Experimental procedure for error measurement.3.A tool position and path compensation method.4.The verification method.

Eung-Suk Leer; Suk-Hwan Suh; Jin-Wook Shon

1998-01-01

196

Basic CNC Operation. Training Workbook [and] Assessment and Training Guide [and] Hands-on Assessment.  

ERIC Educational Resources Information Center

|This workbook is intended for students taking a course in basic computer numerical control (CNC) operation that was developed during a project to retrain defense industry workers at risk of job loss or dislocation because of conversion of the defense industry. The workbook contains daily training guides for each of the course's 13 sessions. Among…

Anoka-Hennepin Technical Coll., Minneapolis, MN.

197

Computer-aided optimization of multi-pass turning operations for continuous forms on CNC lathes  

Microsoft Academic Search

The Computer Numerical Control (CNC) machine is one of the most effective production facilities used in manufacturing industry. Determining the optimal machining parameters is essential in the machining process planning since the machining parameters significantly affect production cost and quality of machined parts. Previous studies involving machining optimization of turning operations concentrated primarily on developing machining models for bar components.

CHAO-TON Su; MU-CHEN Chen

1999-01-01

198

Dynamic transmission error analysis for a CNC machine tool based on built-in encoders  

Microsoft Academic Search

The dynamic transmission error of a CNC machine tool affects the manufacturing precision significantly. It may be caused by many factors, such as the geometric error of the transmission parts, the defects on the tooth flank as well as the torsional vibration of running shafts etc. It is very important to locate where the major source is so as to

Ming Zhao; Jing Lin; Xiufeng Wang; Yuhe Liao

2011-01-01

199

EXPERIMENTAL INVESTIGATION AND DEVELOPMENT OF MATHEMATICAL CORRELATIONS OF CUTTING PARAMETERS FOR MACHINING GRAPHITE WITH CNC WEDM  

Microsoft Academic Search

The Wire cut electrical discharge machining is found to have tremendous potential in the present day metal cutting process, for achieving improved geometric features of work pieces, dimensional accuracy, surface finish etc. Improving the productivity in CNC WEDM depends solely on optimization of various process parameters viz... discharge current, thickness etc. Thus the present work is aimed at experimental evaluation

Ch. V. S. ParameswaraRao; M. M. M. Sarcar

2009-01-01

200

A real-time NURBS surface interpolator for precision three-axis CNC machining  

Microsoft Academic Search

Due to the fact that the cutting occurs around the cutter contact (CC) point, the efficiency and quality of CNC machining can be improved significantly if the CC velocity along the surface is kept costant. Conventional approaches to machining mainly maintain a constant cutter location (CL) velocity, so that the CC velocity along the surface is often not constant and

M.-C. Tsai; C.-W. Cheng; M.-Y. Cheng

2003-01-01

201

NURBS-based fast geometric error compensation for CNC machine tools  

Microsoft Academic Search

In this paper, a novel method for the compensation of geometric errors of CNC machine tools is presented. The key idea is to use the basis functions of the setting NURBS path to approximate its error compensation function and to generate a new compensated NURBS path. In this way, both the setting and the compensated NURBS path have the same

W. T. Lei; M. P. Sung

2008-01-01

202

A real-time scheme of cubic parametric curve interpolations for CNC systems  

Microsoft Academic Search

In this paper, the popular finite forward differencing algorithm for fast evaluation of points on a cubic parametric curve is modified for its application to CNC systems so that the inherent accumulative error in the calculation of one piece of curve will not propagate to the whole composite curve. Using specified tolerances, a computationally non-intensive method of analysis for the

Behnam Bahr; Xiaomao Xiao; Krishnan Krishnan

2001-01-01

203

Complexity of CNC transcription factors as revealed by gene targeting of the Nrf3 locus.  

PubMed

Cap'n'collar (CNC) family basic leucine zipper transcription factors play crucial roles in the regulation of mammalian gene expression and development. To determine the in vivo function of the CNC protein Nrf3 (NF-E2-related factor 3), we generated mice deficient in this transcription factor. We performed targeted disruption of two Nrf3 exons coding for CNC homology, basic DNA-binding, and leucine zipper dimerization domains. Nrf3 null mice developed normally and revealed no obvious phenotypic differences compared to wild-type animals. Nrf3(-/-) mice were fertile, and gross anatomy as well as behavior appeared normal. The mice showed normal age progression and did not show any apparent additional phenotype during their life span. We observed no differences in various blood parameters and chemistry values. We infected wild-type and Nrf3(-/-) mice with acute lymphocytic choriomeningitis virus and found no differences in these animals with respect to their number of virus-specific CD8 and CD4 T cells as well as their B-lymphocyte response. To determine whether the mild phenotype of Nrf3 null animals is due to functional redundancy, we generated mice deficient in multiple CNC factors. Contrary to our expectations, an absence of Nrf3 does not seem to cause additional lethality in compound Nrf3(-/-)/Nrf2(-/-) and Nrf3(-/-)/p45(-/-) mice. We hypothesize that the role of Nrf3 in vivo may become apparent only after appropriate challenge to the mice. PMID:15060151

Derjuga, Anna; Gourley, Tania S; Holm, Teresa M; Heng, Henry H Q; Shivdasani, Ramesh A; Ahmed, Rafi; Andrews, Nancy C; Blank, Volker

2004-04-01

204

RS CVn-type variables  

Microsoft Academic Search

Photometric observation of HR 1099 inV andB obtained on 18 nights between January and March 1977 is presented. The amplitude of the asymmetric light curve is found to be 0m.10±0m.004 both inV andB. On three occasions—namely, JD 2443164. 17, JD 2443176. 14 and JD 2443177.12—the star brightened by ~ 0m.05. Four Ha spectrograms at 42 Å mm-1 dispersion were obtained

M. Parthasarathy; A. V. Raveendran; M. V. Mekkaden

1981-01-01

205

The resonance line of B II in IUE spectra of chemically peculiar stars  

NASA Astrophysics Data System (ADS)

A description is presented of high-dispersion spectroscopic observations of eight chemically peculiar stars including Kappa Cnc and Mu Lep, and of one normal comparison star, Nu Cap, in the vicinity of 1362 A. The reported data were obtained with the International Ultraviolet Explorer during the first 15 months of its operation. The initial reduction of the data, which were originally described in a qualitative summary by Leckrone (1980), was affected by a serious error in the calibration of the instrument's intensity transfer function. This error has been corrected in the currently presented data. The results of spectrum syntheses of the 1362 A feature are also described for several of the stars.

Leckrone, D. S.

1981-11-01

206

CCD Photometric Study of the Contact Binary TX Cnc in the Young Open Cluster NGC 2632  

NASA Astrophysics Data System (ADS)

TX Cnc is a member of the young open cluster NGC2632. In the present paper, four CCD epochs of light minimum and a complete V light curve of TX Cnc are presented. A period investigation based on all available photoelectric or CCD data showed that it is superimposed on a long-term increase (dP/dt=+3.97×10-8) and weak evidence suggests that it includes a small-amplitude period oscillation (A3=0d.0028; T3=26.6yr). The light curves in the V band obtained in 2004 were analyzed with the 2003 version of the W-D code. It was shown that TX Cnc is an overcontact binary system with a degree of contact factor f=24.8%. The absolute parameters of the system were calculated: M1=1.319±0.007M?, M2=0.600±0.01M?; R1=1.28±0.19R?, R2=0.91±0.13R?. TX Cnc may be on the TRO-controlled stage of the evolutionary scheme proposed by Qian (2001a, b, 2003a), and may contain an invisible tertiary component (m3?0.097M?). If this is true, the tertiary component has played an important role in the formation and evolution of TX Cnc by removing angular momentum from the central system (Pribulla & Rucinski 2006). In this way the contact binary configuration can be formed in the shortlife time of a young open cluster via AML.

Liu, Liang; Qian, Sheng-Bang; Boonrucksar, Soonthornthum; Zhu, Li-Ying; He, Jia-Jia; Yuan, J.-Z.

2007-06-01

207

X-ray and optical variability in 2A1052+606 - A new RS CVn-type system  

Microsoft Academic Search

The paper discusses a star with RS CVn-type characteristics discovered as a result of an accurate X-ray location. The RS CVn binaries have been found to be a new class of soft X-ray sources from the HEAO 1 low energy sky survey. The source was detected at energies below 1 keV and evidence is presented for variability on time scales

Philip Charles; Frederick Walter; Stuart Bowyer

1979-01-01

208

Basic leucine zipper protein Cnc-C is a substrate and transcriptional regulator of the Drosophila 26S proteasome.  

PubMed

While the 26S proteasome is a key proteolytic complex, little is known about how proteasome levels are maintained in higher eukaryotic cells. Here we describe an RNA interference (RNAi) screen of Drosophila melanogaster that was used to identify transcription factors that may play a role in maintaining levels of the 26S proteasome. We used an RNAi library against 993 Drosophila transcription factor genes to identify genes whose suppression in Schneider 2 cells stabilized a ubiquitin-green fluorescent protein reporter protein. This screen identified Cnc (cap 'n' collar [CNC]; basic region leucine zipper) as a candidate transcriptional regulator of proteasome component expression. In fact, 20S proteasome activity was reduced in cells depleted of cnc. Immunoblot assays against proteasome components revealed a general decline in both 19S regulatory complex and 20S proteasome subunits after RNAi depletion of this transcription factor. Transcript-specific silencing revealed that the longest of the seven transcripts for the cnc gene, cnc-C, was needed for proteasome and p97 ATPase production. Quantitative reverse transcription-PCR confirmed the role of Cnc-C in activation of transcription of genes encoding proteasome components. Expression of a V5-His-tagged form of Cnc-C revealed that the transcription factor is itself a proteasome substrate that is stabilized when the proteasome is inhibited. We propose that this single cnc gene in Drosophila resembles the ancestral gene family of mammalian nuclear factor erythroid-derived 2-related transcription factors, which are essential in regulating oxidative stress and proteolysis. PMID:21149573

Grimberg, Kristian Björk; Beskow, Anne; Lundin, Daniel; Davis, Monica M; Young, Patrick

2010-12-13

209

Eu Abundances in Active and Non-Active Stars  

NASA Astrophysics Data System (ADS)

Eu abundances have been determined for stars observed at high resolution, high signal to noise ratio with the ELODIE spectrograph at the 1.93- m telescope of the Observatoire de Haute Provence (France). Among them more than 30 stars are active stars with a fraction of BY Dra and RS CVn type stars for which spectral pecularities were investigated. For all stars fundamental parameters were determined earlier. We find the mean abundances of the majority of elements in active and non-active stars. Active and non active cool dwarfs show similar dependencies of elemental ratios vs [Fe/H].

Gorbaneva, T. I.; Mishenina, T. V.

2010-12-01

210

RS CV sub n binary systems  

SciTech Connect

An attempt is made to place in context the vast amount of data obtained as a result of X-ray, ultraviolet, optical, and microwave observations of RS CVn and similar spectroscopic binary systems. Emphasis is on the RS CVn systems and their long period analogs. The following questions are considered: (1) are the original defining characteristics still valid and still adequate; (2) what is the evidence for discrete active regions; (3) have any meaningful physical properties for the atmospheres of RS CVn systems been derived; (4) what do the flare observations tell about magnetic fields in RS CVn systems; (5) is there evidence for systematic trends in RS CVn systems with spectral type.

Linsky, J.L.

1984-01-01

211

Observations and a new interpretation for the delta Scuti variable star VZ Cancri  

SciTech Connect

Extensive numbers of new photoelectric data have been collected and analyzed to investigate the modal behavior of VZ Cnc. Its previously observed periods yield a period ratio of 0.80 implying pulsation in the first and second radial overtones. Of the seventeen delta Scuti stars listed by Fitch and Sziedl which have well-determined periods, it is the only star which apparently does not pulsate in the fundamental mode. This peculiarity is investigated from the standpoint of a change with time of the dominant pulsation mode and atmospheric helium settling. The former suggestion is found to be untenable. The latter is found to increase the theoretical ratio of the first overtone/fundamental periods to that observed. It is thus suggested that VZ Cnc pulsates in these lowest order modes and that its atmosphere has been largely depleted of helium. However, if VZ Cnc has a temperatur as large as 7500 K, its position in the instability strip places this star near the transition line between the first and second overtone pulsation modes, beyond the fundamental mode blue edge. In this case the fundamental mode cannot exist, and the 1H and 2H modes are properly identified.

Cox, A.N.; McNamara, B.J.; Ryan, W.

1984-09-01

212

Research on efficient and stable milling using CNC small size tool  

NASA Astrophysics Data System (ADS)

In order to mill efficiently and stably using small size tool on computer numerical control machine(CNC machine), the paper establishes dual-objective function on the basis of the minimum tool wear and the largest cutting efficiency. Meanwhile, the influence of diameter and length of tool suspended on stability is considered under the guidance of chatter stability analysis relationship. Research results show that, Pareto solution set which has two factors into account conflicting can be obtained by Genetic Algorithms, combined Pareto solution set with the frequency response function (FRF) chatter stability diagram, Pareto solutions of the smaller range of options, the milling parameters which meet the requirements of efficient and stable milling of CNC machine tools can be optimized conveniently and accurately. When the tool suspended length increases, the system stiffness decreases and the chatter stability domain graphic drops down, Stability region narrows.

Luo, Yongxin; Zhao, Beichen; Long, Hua; Yu, Nanlin

2010-12-01

213

Design and fabrication of an acrylic-based 1×2 POF coupler using CNC Machining  

Microsoft Academic Search

A low cost acrylic-based 1times2 Plastic optical fiber (POF) coupler has been designed and fabricated. The POF coupler has a middle waveguide taper made of UV curable glue and POF fibers for the input and output ports. Non-sequential ray tracing has been performed on the POF coupler. Mold insert has been fabricated using EGX-400 desktop CNC machining with a groove

Abang Annuar Ehsan; Sahbudin Shaari; M. Rahman

2008-01-01

214

NC flame pipe cutting machine tool based on open architecture CNC system  

Microsoft Academic Search

Based on the analysis of the principle and flame movement of a pipe cutting machine tool, a retrofit NC flame pipe cutting\\u000a machine tool (NFPCM) that can meet the demands of cutting various pipes is proposed. The paper deals with the design and implementation\\u000a of an open architecture CNC system for the NFPCM, many of whose aspects are similar to

Xiaogen Nie; Yanbing Liu

2009-01-01

215

A Hybrid-Coded Genetic Algorithm Based Optimisation of NonProductive Paths in CNC Machining  

Microsoft Academic Search

In order to optimise the non-productive paths in CNC machining under entry or exit constraints (such as in laser engraving\\u000a and flame cutting), a hybrid-coded genetic algorithm (HCGA) is proposed in this paper. There are two chromosomes in the HCGA.\\u000a One chromosome, called the master chromosome, uses a natural number-coded mode, and represents the sequence of productive\\u000a contours. The other

T. X. Zhong; J. C. Chen

2002-01-01

216

Real-time generation and control of cutter path for 5-axis CNC machining  

Microsoft Academic Search

This paper presents a new approach to real-time generation and control of the cutter path for 5-axis machining applications. The cutter path generation method comprises real-time algorithms for cutter-contact path interpolation, cutter offsetting, and coordinate conversion. In addition, a global feedback loop is closed by the CNC interpolator so as to augment the controlled accuracy in practical cutter path generation.

Chih-Ching Lo

1999-01-01

217

Comparison between predicted and actual accuracies for an Ultra-Precision CNC measuring machine  

SciTech Connect

At the 1989 CIRP annual meeting, we reported on the design of a specialized, ultra-precision CNC measuring machine, and on the error budget that was developed to guide the design process. In our paper we proposed a combinatorial rule for merging estimated and/or calculated values for all known sources of error, to yield a single overall predicted accuracy for the machine. In this paper we compare our original predictions with measured performance of the completed instrument.

Thompson, D.C.; Fix, B.L.

1995-05-30

218

Thread milling on N/C and CNC milling machines. Final report  

SciTech Connect

A unique thread-cutting tool design has been developed which permits threading of internal or external features; right- or left-hand threads; and standard, metric, or special pitches within a given size range without changing tools. One of the major advantages of the technique is the ability to produce small threads on N/C and CNC milling manchines. This study presents results showing fabrication of quality threads as small as number 0-80 in selected materials.

Ashbaugh, F.A.; Murry, K.R.

1985-12-01

219

CNC machine tool surface interpolator for ball-end milling of free-form surfaces  

Microsoft Academic Search

This paper presents a new type of CNC machine tool interpolator that is capable of generating the cutter path for ball-end milling of a free-form surface. The surface interpolator comprises on-line algorithms for cutter-contact (CC) path scheduling, CC path interpolation, and tool offsetting. The interpolator algorithms for iso-parametric, iso-scallop and iso-planar machining methods are developed, respectively. The proposed surface interpolator

Chih-Ching Lo

2000-01-01

220

Intelligent cross-coupled fuzzy feedrate controller design for CNC machine tools based on genetic algorithms  

Microsoft Academic Search

In this paper, an intelligent contour control strategy has been investigated to improve the contour error of CNC machine tools. An uncoupled contour control system is first analyzed and then a cross-coupled controller is added in the control loop to form a cross-coupled contour control system. An algorithm for an on-line estimation of the contour error in arbitrary curved contouring

Y. S. Tarng; H. Y. Chuang; W. T. Hsu

1999-01-01

221

Five-axis CNC milling for effective machining of sculptured surfaces  

Microsoft Academic Search

In machining of sculptured surfaces on five-axis CNC milling machines, determination of the direction vector of the milling cutter is very important. The direction vector is obtained from the fact that the bottom part of the milling cutter rides on free-form surfaces using a z-map method, and this can be applied to all geometric types of sculptured surfaces. After generating

H. D. CHO; Y. T. JUN; M. Y. YANG

1993-01-01

222

A Study on an Open Architecture CNC System with a NURBS Interpolator for WEDM  

Microsoft Academic Search

This paper deals with the design and implementation of an open architecture CNC system for wire electrical discharge machining\\u000a (WEDM) with a consideration of the differences between WEDM and NC cutting machines. Work using open architecture controllers\\u000a (OACs) has focused mainly on metal cutting machines. WEDM has many aspects similar to milling machines. However, there are\\u000a differences in the machining

M.-Y. Yang; J.-H. Park

2002-01-01

223

Fast real-time NURBS path interpolation for CNC machine tools  

Microsoft Academic Search

In this paper, a novel fast real-time non-uniform rational B-spline (NURBS) path interpolation method is presented. This method efficiently integrates the data processing of a NURBS path in a CNC controller, from pre-processing to real-time interpolation. In the calculation of the total length of the NURBS path, the numerical adaptive quadrature method adapts to the integrand, i.e. the first derivative

W. T. Lei; M. P. Sung; L. Y. Lin; J. J. Huang

2007-01-01

224

An adaptive real-time NURBS interpolator for CNC machine tools  

Microsoft Academic Search

This paper presents a real-time interpolation method along non-uniform rational B-spline (NURBS) curves which have been used by CNC systems. The development of NURBS interpolator promises modern manufacturing system to machine arbitrary geometries with great relief of the data-flow bottleneck. In this interpolation algorithm, an Adams-Bashforth method is used as a predictor to predict the next trajectory point on the

H. Hu; X. T. Zhang

2009-01-01

225

Speed optimization control method of smooth motion for high-speed CNC machine tools  

Microsoft Academic Search

An integer optimization model for feedrate of smooth motion is developed to realize high-speed and smooth motion for high-speed\\u000a computer numerical control (CNC) machine tools. In this model, the turning factor of the machining segments is transformed\\u000a into the corresponding linked feedrate limit, and the axis feedrate and feed acceleration limits are also considered. Because\\u000a the number of both decision

Lin Wang; Jianfu F. Cao; Yuqiang Q. Li

2010-01-01

226

NURBS Interpolation Method with Feedrate Correction in 3-axis CNC System  

Microsoft Academic Search

A real-time non-uniform rational B-spline (NURBS) curve directly interpolation method is presented for computer numerical control (CNC) machines to achieve the goal of high-speed and highly accurate machining. To the feedrate fluctuation of the interpolation method, the feedrate correction method is also proposed. To implement the proposed methods, Taylor expansion and numerical calculation methods are used. The given example shows

Chen Liangji; Li Huiying

2009-01-01

227

Method of NURBS interpolation with ACC\\/DEC controlling in 5-axis CNC system  

Microsoft Academic Search

Because of the huge advantages of Non-Uniform Rational B-Spline(NURBS) curves to represent arbitrary types of curve, an interpolation method using NURBS technology in the CAD field is proposed and realized in a 5-axis CNC system. In this method, the tool path was represented to two NURBS curves, tool-tip and tool-orientation spline curve, based on the same knot vector. CL data

Chen Liangji; Feng Xianzhang

2010-01-01

228

Method of 5-axis Spline Interpolation and Realization in CNC System  

Microsoft Academic Search

An interpolation method using non-uniform rational B-spline (NURBS) technology in the CAD field is proposed and realized in a 5-axis computer numerically controlled (CNC) system. In this method, the tool path is represented to two NURBS curves, tool-tip and tool-orientation spline curve, based on the same knot vector. CL data is firstly calculated and then transformed to five motion commands

Liangji Chen

2009-01-01

229

Real-time variable feed rate NURBS curve interpolator for CNC machining  

Microsoft Academic Search

This paper presents a real-time control algorithm based on Taylor’s expansion for implementing variable feed rate non-uniform rational B-spline (NURBS) curve interpolators using a digital signal processor for precision CNC machining. To efficiently compute the NURBS curve and its derivatives in real-time, an effective method is proposed. The variable feed rate NURBS curve interpolator can be used to realise the

C.-W. Cheng; M.-C. Tsai

2004-01-01

230

Real-time PH curve CNC interpolators for high speed cornering  

Microsoft Academic Search

In this paper, real-time Pythagorean hodograph (P-H) curve CNC interpolators are used for high speed corner machining. There\\u000a are large contouring errors around sharp corners when low-bandwidth servo controllers (such as P-PI control) are used. In\\u000a order to decrease the amount of the cornering errors, an improved interpolation method is proposed. The first deceleration\\u000a phase of motion and the over-corner

Javad Jahanpour; Behnam Moetakef Imani

2008-01-01

231

Algorithms for time–optimal control of CNC machines along curved tool paths  

Microsoft Academic Search

The problem of specifying the feedrate variation along a curved path, that yields minimum traversal time for a 3-axis CNC machine subject to constraints on the feasible acceleration along each axis, is addressed. In general, this time–optimal feedrate incurs “bang–bang control,” i.e., maximum acceleration\\/deceleration is demanded of at least one axis throughout the motion. For a path defined by a

Sebastian D. Timar; Rida T. Farouki; Tait S. Smith; Casey L. Boyadjieff

2005-01-01

232

Exact Taylor series coefficients for variable-feedrate CNC curve interpolators  

Microsoft Academic Search

Abstract Recent papers [Yang DCH, Kong T. Computer Aided Design 1994;26:225?34; Yeh S-S, Hsu P-L. Computer Aided Design 1999;31:349? 57] formulate real-time CNC interpolators for variable feedrates along parametric curves. These interpolators employ,truncated Taylor series to compute successive reference-point parameter values, but in both papers an erroneous coefficient for the highest (quadratic) term is cited. The derivation of the proper

Rida T. Farouki; Yi-feng Tsai

2001-01-01

233

Contour machining of free-form surfaces with real-time PH curve CNC interpolators  

Microsoft Academic Search

Two strategies for contour milling of free-form surfaces, using real-time CNC interpolators for Pythagorean-hodograph (PH) curves, are described. The first method, applicable to convex surfaces, employs a flat-end mill and approximates the surface section curves by planar PH quintics. The second approach, which employs a ball-end mill, approximates the tool-center trajectory by quintic PH space curves, and can accommodate nonconvex

Rida T. Farouki; Yi-feng Tsai; Guo-feng Yuan

1999-01-01

234

A CNC machine tool interpolator for surfaces of cross-sectional design  

Microsoft Academic Search

A machining strategy for milling a particular set of surfaces, obtained by the technique of cross-sectional design is proposed. The surfaces considered are formed by sliding a Bezier curve (profile curve) along another Bezier curve (trajectory curve). The curves are located in perpendicular planes. The method employs a three-axis CNC milling machine equipped with suitable ball-end cutter and is based

Sotiris L. Omirou; Andreas C. Nearchou

2007-01-01

235

Performance analysis of CNC interpolators for time-dependent feedrates along PH curves  

Microsoft Academic Search

Virtually any desired time variation V(t) of the feedrate along a curved path can be realized by real-time CNC interpolator algorithms for the Pythagorean-hodograph (PH) curves: the only stipulation is that V(t) should admit a closed-form indefinite integral F(t). Different feedrate variations V(t) can be accommodated with minimal modifications to the core algorithm by employing a modular function call to

Yi-feng Tsai; Rida T. Farouki; Bryan Feldman

2001-01-01

236

The application of reconfigurable logic to high speed CNC milling machines controllers  

Microsoft Academic Search

Reconfigurable logic has gained relevance in high-speed computer numerical control (CNC) digital controllers where high processing speed at the servo loop update time is critical. Reconfigurable devices like field programmable gate array (FPGA) have advantages over microprocessors and DSP with similar logic complexity because their open architecture makes them suitable for system on-a-chip applications. The contribution of this work is

Roque Alfredo Osornio-Rios; Rene de Jesus Romero-Troncoso; Gilberto Herrera-Ruiz; Rodrigo Castañeda-Miranda

2008-01-01

237

Spots on T Tauri stars  

NASA Astrophysics Data System (ADS)

Periodic light curves were recorded for the following 15 T Tauri stars (for nine of which this was the first detection of periodic variability): V 410 Tau, DF Tau, UX Tau A, FK 1, FK 2, WK 2, DN Tau, GW Ori, SY Cha, LH(alpha) 332-20, LH(alpha) 332-21, CoD-33-deg 10685, RY Lup, SR 12, and SR 9. The previously reported periodic variability of the SY Cha and RY Lup stars was confirmed. These periodic variations are thought to result from rotational modulation by a group of spots at the stellar surface. The properties of spots on 11 stars were deduced from extensive light-curve synthesis. In most cases, they were found to be comparable to the properties of spots found on RS CVn stars.

Bouvier, J.; Bertout, C.

1989-02-01

238

n-Capture Elemental Abundances in Active and Non-Active Stars  

NASA Astrophysics Data System (ADS)

Abundances of Y, Zr, La, Ce, Nd, and Sm have been obtained under LTE approximationss. The program stars were observed at high resolution, high signal to noise ratio with the ELODIE echelle spectrograph (OHP, France). Among them more than 30 stars are active stars with a fraction of BY Dra and RS CVn type stars. Comparison of the behavior of n-capture elemental abundance in active and non active stars was made.

Basak, N. Yu.; Mishenina, T. V.; Soubiran, C.; Kovtyukh, V. V.; Belik, S. I.

2010-12-01

239

The Metallicity and Lithium Abundances in the Repeating Novae, RS Oph and T CrB  

NASA Astrophysics Data System (ADS)

The subclass of symbiotic stars that has been suggested to be one of the sources of supernovae of type Ia is the repeating novae. Spectroscopic orbits of TCrB and RS Oph indicate that the white dwarfs in those systems have masses close to 1.4 MSun and hence they are vulnerable to catastrophic collapse if they accumulate additional mass from their red giant companions. To investigate the nature of their companions we obtained high res (35,000) spectra of both RS Oph and TCrB in 2004 with the echelle spectrograph of the Apache Point 3.5-m telescope. The purpose was to derive as much information about the red giant component that has been losing mass, some of which has probably been captured by the white dwarf. Of particular interest is the possibility that the red giant has lost much of its hydrogen envelope which might indicate that the mass-transfer process had reached the point that a supernova outburst (rather than just a repeat of the nova outburst) is imminent. Standard methods were used to derive the effective temperature and gravity of the cool star. Using model atmospheres we have been able to derive the metallicity of the stars. Using lines of Si, Ti, Fe and Ni we found RS Oph to show small metal excess. A small metal deficiency was found for TCrB. Within the uncertainties a solar metallicity is possible for both stars. Both stars show a strong Li line. For 41 other symbiotic stars observed at the Asiago Observatory, 28 showed no Li line and 13 were too severely blended to make a judgment. It is not clear if the lithium in the two repeating nova systems is due to processes within the red giant or to capture by the red giant of Li produced in the nova explosions.

Wallerstein, George; Harrison, T.; Munari, U.

2006-12-01

240

A SUPER-EARTH TRANSITING A NAKED-EYE STAR  

SciTech Connect

We have detected transits of the innermost planet 'e' orbiting 55 Cnc (V = 6.0), based on two weeks of nearly continuous photometric monitoring with the MOST space telescope. The transits occur with the period (0.74 days) and phase that had been predicted by Dawson and Fabrycky, and with the expected duration and depth for the crossing of a Sun-like star by a hot super-Earth. Assuming the star's mass and radius to be 0.963{sup +0.051}{sub -0.029} M{sub sun} and 0.943 {+-} 0.010 R{sub sun}, the planet's mass, radius, and mean density are 8.63 {+-} 0.35 M{sub +}, 2.00 {+-} 0.14 R{sub +}, and 5.9{sup +1.5}{sub -1.1} g cm{sup -3}, respectively. The mean density is comparable to that of Earth, despite the greater mass and consequently greater compression of the interior of 55 Cnc e. This suggests a rock-iron composition supplemented by a significant mass of water, gas, or other light elements. Outside of transits, we detected a sinusoidal signal resembling the expected signal due to the changing illuminated phase of the planet, but with a full range (168 {+-} 70 ppm) too large to be reflected light or thermal emission. This signal has no straightforward interpretation and should be checked with further observations. The host star of 55 Cnc e is brighter than that of any other known transiting planet, which will facilitate future investigations.

Winn, Joshua N. [Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Matthews, Jaymie M.; Kallinger, Thomas; Dragomir, Diana [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Dawson, Rebekah I.; Holman, Matthew J.; Sasselov, Dimitar [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Fabrycky, Daniel [UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); Kuschnig, Rainer; Weiss, Werner W. [University of Vienna, Institute for Astronomy, Tuerkenschanzstrasse 17, A-1180 Vienna (Austria); Guenther, David B. [Department of Astronomy and Physics, Saint Mary's University, Halifax, NS B3H 3C3 (Canada); Moffat, Anthony F. J. [Department de Physique, Universite de Montreal, C.P. 6128, Succ. Centre-Ville, Montreal, QC H3C 3J7 (Canada); Rowe, Jason F. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Rucinski, Slavek [Department of Astronomy and Astrophysics, University of Toronto, 50 St George Street, Toronto, ON M5S 3H4 (Canada)

2011-08-10

241

Extreme Stars  

Microsoft Academic Search

Over the past 200 years, our knowledge of stars has expanded enormously. From seeing myriad dots of different brightnesses, we haved moved on to measure their distances, temperatures, sizes, chemical compositions, and even ages, finding both young and ancient stars that dwarf our Sun and are dwarfed by it. Unique in its approach, Extreme Stars describes the lives of stars

James B. Kaler

2001-01-01

242

Activity Cycles in Stars with Highly Active Chromospheres  

Microsoft Academic Search

We propose to carry out IUE observations of the highly active RS CVn binaries V711 Tauri. Lambda Andromadas, II Peg, and UX Arietis over the next 2 years (1990 and 1991). These stars have the most extensive IUE archival coverage for stars of this type. and have almost continuous ground-based photometric coverage from about 1975 onward. In addition we shall

Edward F. Guinan

1990-01-01

243

The Mass of the Subdwarf B Star in HD 185510  

Microsoft Academic Search

HD 185510 is an RS CVn star with a K0 III-IV primary and an orbital period of 21 days. The secondary was discovered to be a hot subdwarf B star with IUE. The system also shows eclipses, secondary eclipse being total in the far UV. We propose here to determine the velocity amplitude of the secondary orbit, K2, from high

Theodore Simon

1990-01-01

244

V474 Car: A Rare Halo RS CVn Binary in Retrograde Galactic Orbit  

NASA Astrophysics Data System (ADS)

We report the discovery that the star V474 Car is an extremely active, high velocity halo RS CVn system. The star was originally identified as a possible pre-main-sequence star in Carina, given its enhanced stellar activity, rapid rotation (10.3 days), enhanced Li, and absolute magnitude which places it above the main sequence (MS). However, its extreme radial velocity (264 km s-1) suggested that this system was unlike any previously known pre-MS system. Our detailed spectroscopic analysis of echelle spectra taken with the CTIO 4 m finds that V474 Car is both a spectroscopic binary with an orbital period similar to the photometric rotation period and metal-poor ([Fe/H] sime-0.99). The star's Galactic orbit is extremely eccentric (e ~= 0.93) with a perigalacticon of only ~0.3 kpc of the Galactic center—and the eccentricity and smallness of its perigalacticon are surpassed by only ~0.05% of local F/G-type field stars. The observed characteristics are consistent with V474 Car being a high-velocity, metal-poor, tidally locked, chromospherically active binary, i.e., a halo RS CVn binary, and one of only a few such specimens known.

Bubar, Eric J.; Mamajek, Eric E.; Jensen, Eric L. N.; Walter, Frederick M.

2011-04-01

245

V474 Car: A RARE HALO RS CVn BINARY IN RETROGRADE GALACTIC ORBIT  

SciTech Connect

We report the discovery that the star V474 Car is an extremely active, high velocity halo RS CVn system. The star was originally identified as a possible pre-main-sequence star in Carina, given its enhanced stellar activity, rapid rotation (10.3 days), enhanced Li, and absolute magnitude which places it above the main sequence (MS). However, its extreme radial velocity (264 km s{sup -1}) suggested that this system was unlike any previously known pre-MS system. Our detailed spectroscopic analysis of echelle spectra taken with the CTIO 4 m finds that V474 Car is both a spectroscopic binary with an orbital period similar to the photometric rotation period and metal-poor ([Fe/H] {approx_equal}-0.99). The star's Galactic orbit is extremely eccentric (e {approx_equal} 0.93) with a perigalacticon of only {approx}0.3 kpc of the Galactic center-and the eccentricity and smallness of its perigalacticon are surpassed by only {approx}0.05% of local F/G-type field stars. The observed characteristics are consistent with V474 Car being a high-velocity, metal-poor, tidally locked, chromospherically active binary, i.e., a halo RS CVn binary, and one of only a few such specimens known.

Bubar, Eric J.; Mamajek, Eric E. [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627-0171 (United States); Jensen, Eric L. N. [Swarthmore College, Department of Physics and Astronomy, 500 College Avenue, Swarthmore, PA 19081 (United States); Walter, Frederick M. [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States)

2011-04-15

246

3D simulations of RS Oph: from accretion to nova blast  

Microsoft Academic Search

RS Ophiuchi is a recurrent nova with a period of about 22 years, consisting\\u000aof a wind accreting binary system with a white dwarf (WD) very close to the\\u000aChandrasekhar limit and a red giant star (RG). The system is considered a prime\\u000acandidate to evolve into an SNIa. We present a 3D hydrodynamic simulation of\\u000athe quiescent accretion and

Rolf Walder; Doris Folini; Steven N. Shore

2008-01-01

247

Stars and Star Myths.  

ERIC Educational Resources Information Center

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

Eason, Oliver

248

Finger milling-cutter CNC generating hypoid pinion tooth surfaces based on modified-roll method and machining simulation  

NASA Astrophysics Data System (ADS)

The two coordinate systems of cradle-type hypoid generator and free-form CNC machine tool by application disc milling-cutter to generate hypoid pinion tooth surfaces based on the modified-roll method were set up, respectively, and transformation principle and method for machine-tool settings between the two coordinate systems was studied. It was presented that finger milling-cutter was mounted on imagined disc milling-cutter and its motion was controlled directly by CNC shafts to replace disc milling-cutter blades effective cutting motion. Finger milling-cutter generation accomplished by ordered circular interpolation was determined, and interpolation center, starting and ending were worked out. Finally, a hypoid pinion was virtually machined by using CNC machining simulation software VERICUT.

Li, Genggeng; Deng, Xiaozhong; Wei, Bingyang; Lei, Baozhen

2010-12-01

249

A search for wide visual companions of exoplanet host stars: The Calar Alto Survey  

NASA Astrophysics Data System (ADS)

We have carried out a search for co-moving stellar and substellar companions around 18 exoplanet host stars with the infrared camera MAGIC at the 2.2 m Calar Alto telescope, by comparing our images with images from the all sky surveys 2MASS, POSS I and II. Four stars of the sample namely HD 80606, 55 Cnc, HD 46375 and BD-10°3166, are listed as binaries in the Washington Visual Double Star Catalogue (WDS). The binary nature of HD 80606, 55 Cnc, and HD 46375 is confirmed with both astrometry as well as photometry, thereby the proper motion of the companion of HD 46375 was determined here for the first time. We derived the companion masses as well as the longterm stability regions for additional companions in these three binary systems. We can rule out further stellar companions around all stars in the sample with projected separations between 270 AU and 2500 AU, being sensitive to substellar companions with masses down to ˜ 60 {MJup} (S/N=3). Furthermore we present evidence that the two components of the WDS binary BD-10°3166 are unrelated stars, i.e this system is a visual pair. The spectrophotometric distance of the primary (a K0 dwarf) is ˜ 67 pc, whereas the presumable secondary BD-10°3166 B (a M4 to M5 dwarf) is located at a distance of 13 pc in the foreground.

Mugrauer, M.; Neuhäuser, R.; Mazeh, T.; Guenther, E.; Fernández, M.; Broeg, C.

2006-05-01

250

Setup for Triggering Force Testing of Touch Probes for CNC Machine Tools and CMMs  

NASA Astrophysics Data System (ADS)

Touch-trigger probes are commonly used both in coordinate measuring machines (CMM) and in computer numerical control (CNC) machine tools. In both cases accuracy of measurement of the overall system and probing unit are closely interrelated. Key parameters of the probes are repeatability and pre-travel variation dependent on adjustable stylus force. To enable testing of the triggering force of the probes, the new setup was developed. The principle of the method and set-up is presented and its validity is experimentally confirmed.

Wozniak, A.; Byszewski, M.; Jankowski, M.

2013-01-01

251

Variable stars  

SciTech Connect

This book covers the following topics: pulsating variables; eruptive variables; eclipsing stars; supplement to the classification; the discovery of variable stars; the significance of variable stars for research on the structure of the galaxy and stellar evolution; and observational methods and organizations.

Hoffmeister, C.; Richter, G.; Wenzel, W.

1985-01-01

252

The Asymmetric Outflow of RS Ophiuchi  

NASA Astrophysics Data System (ADS)

RS Ophiuchi (RS Oph) is a symbiotic binary consisting of a hot white dwarf accreting from the slow, dense stellar wind of a cool, red giant companion. The system belongs to, and is one of the best studied examples of, an even smaller subclass of binaries known as recurrent novae in which the white dwarf undergoes repeated thermonuclear outbursts. We present 3D smoothed particle hydrodynamics (SPH) models of mass transfer from the red giant to the white dwarf, followed by a nova outburst. We show that the outflow in the former is strongly concentrated towards the binary orbital plane. The nova ejecta is thus constrained in the equatorial directions, resulting in a bipolar outflow. The white dwarf in RS Oph is thought to be close to the Chandrasekhar mass, making the system a likely Type Ia supernova candidate. We discuss the role that such a highly structured circumstellar medium will play in the evolution of the supernova remnant.

Mohamed, S.; Booth, R.; Podsiadlowski, Ph.

2013-01-01

253

EUV Emission from RS Canum Venaticorum binaries.  

NASA Astrophysics Data System (ADS)

We performed a study of 104 RS CVn systems in the extreme ultraviolet (EUV) using the all-sky survey data obtained by the Extreme Ultraviolet Explorer (EUVE). The present sample includes several new RS CVn detections; 11 more than in the published EUVE catalogs, and 8 more than in the ROSAT Wide Field Camera catalog. The ratio of detections to non-detections remained constant throughout the sky, implying that our detections are not limited by the exposure time but are most likely limited by absorption from the interstellar medium. A general trend of increasing Lex/B (50-180Å) flux with decreasing rotational period is clear. The dwarf systems exhibit a leveling-off for the faster rotators. In contrast, the evolved systems exhibit no such effect. For the RS CVn systems the losses in the EUV represent a smaller fraction of the coronal radiative losses, as compared to active late-type dwarfs.

Mitrou, C. K.; Mathioudakis, M.; Doyle, J. G.; Antonopoulou, E.

1997-02-01

254

HST Fine Guidance Sensor Parallaxes for WZ Sge, YZ Cnc, and RU Peg: Calibration of the Outburst MV - POrb Relationship for CVs  

NASA Astrophysics Data System (ADS)

We have used the Fine Guidance Sensors on the HST to generate high precision parallaxes for the cataclysmic variables WZ Sge, YZ Cnc, and RU Peg. These three objects span an orbital period range from 1.36 hr (WZ Sge) up to 8.99 hr (RU Peg). These new values, combined with existing HST parallaxes, allow us to calibrate the outburst absolute magnitude versus orbital period MV - POrb relationship. We find a remarkably tight relationship after accounting for the orbital inclinations of the sample systems. In addition, we find that four other CV systems that exhibit rare outbursts of unknown type and for which we have HST FGS parallaxes (EX Hya, V1223 Sgr, TV Col, and RW Tri) are consistent with this relationship. This finding suggests that the rare outbursts of these four systems are due to normal dwarf nova disk instability events. We will also use optical and infrared photometry to examine the nature of the secondary stars in these systems. Funding for this research has been provided by NASA through the HST Guest Observer program under grant GO-09089.

Johnson, J. J.; Harrison, T. E.; Howell, S. B.; Szkody, P.; McArthur, B. E.; Benedict, G. F.

2003-05-01

255

TYC 8380-1953-1: Discovery of an RS CVn Binary Through the XMM-Newton Slew Survey  

NASA Astrophysics Data System (ADS)

In this article we report the discovery of the chromospherically active (RS CVn type) binary TYC 8380-1953-1 through the XMM-Newton slew survey and present results of our optical and X-ray follow-up. With a flux limit of 6×10-13 ergs cm-2 s-1 in the soft band (0.2--2 keV), the XMM-Newton slew has a similar sensitivity to the ROSAT All Sky Survey, allowing interesting sources to be identified by their long-term variability. Two different types of stellar sources are detected in shallow X-ray surveys: young stars (both pre--main- and main-sequence stars) and chromospherically active binaries (BY Dra and RS CVn-type systems). The discovery of stars in such surveys and the study of their nature through optical follow-ups is valuable to determine their spatial distribution and scale height in the Galaxy. Our analysis shows that TYC 8380-1953-1 is a double-lined spectroscopic binary, with both components having similar spectral type (likely K0/2 + K3/5) and luminosity. With a typical coronal temperature for an RS CVn system (kT˜1.15 keV) and an X-ray luminosity in the 0.3--10 keV energy band higher than 4×1031 erg s-1, TYC 8380-1953-1 lies among the most X-ray luminous RS CVn binaries.

López-Santiago, J.; Stelzer, B.; Saxton, R.

2012-07-01

256

Experimental Investigation of Parameters of CNC Turning by Taguchi based Grey Relational Analysis  

NASA Astrophysics Data System (ADS)

The AISI H13, a chromium based hot work tool Steel has a wide variety of applications in aluminum casting and extrusion dies, forging dies, hot nut tools, hot header dies, extrusion mandrels, plastic molds, cores, die holder blocks, hot press dies and specially hot work punches etc. In this study, the optimization of two response parameters (Surface roughness and Material Removal Rate) by three machining parameters (cutting speed, feed rate and depth of cut) is investigated in high speed turning of H13 in dry conditions. Taguchi's L'18 orthogonal array and analysis of variance (ANOVA) are used for individual optimization. The simultaneous optimization is done by Grey Relational Analysis approach. The different levels of all machining parameters are used and experiments are done on HMT STALLION-100 HS CNC lathe machine. The optimum condition for combined effects was found V5-F1-D1 and the optimal value of the surface roughness (Ra) comes out to be 0.85 (μm) and of MRR is 488.8 (mm³/sec). The optimum results are also verified with the help of confirmation experiments. Keywords: CNC Turning, O

Sharma, Pankaj; Bhambri, Kamaljeet

2013-03-01

257

AT Cnc: A SECOND DWARF NOVA WITH A CLASSICAL NOVA SHELL  

SciTech Connect

We are systematically surveying all known and suspected Z Cam-type dwarf novae for classical nova shells. This survey is motivated by the discovery of the largest known classical nova shell, which surrounds the archetypal dwarf nova Z Camelopardalis. The Z Cam shell demonstrates that at least some dwarf novae must have undergone classical nova eruptions in the past, and that at least some classical novae become dwarf novae long after their nova thermonuclear outbursts, in accord with the hibernation scenario of cataclysmic binaries. Here we report the detection of a fragmented 'shell', 3 arcmin in diameter, surrounding the dwarf nova AT Cancri. This second discovery demonstrates that nova shells surrounding Z Cam-type dwarf novae cannot be very rare. The shell geometry is suggestive of bipolar, conical ejection seen nearly pole-on. A spectrum of the brightest AT Cnc shell knot is similar to that of the ejecta of the classical nova GK Per, and of Z Cam, dominated by [N II] emission. Galaxy Evolution Explorer FUV imagery reveals a similar-sized, FUV-emitting shell. We determine a distance of 460 pc to AT Cnc, and an upper limit to its ejecta mass of {approx}5 Multiplication-Sign 10{sup -5} M {sub Sun }, typical of classical novae.

Shara, Michael M.; Mizusawa, Trisha; Zurek, David [Department of Astrophysics, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024-5192 (United States); Wehinger, Peter [Steward Observatory, the University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Martin, Christopher D.; Neill, James D.; Forster, Karl [Department of Physics, Math and Astronomy, California Institute of Technology, 1200 East California Boulevard, Mail Code 405-47, Pasadena, CA 91125 (United States); Seibert, Mark [Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

2012-10-20

258

CNC machine tool's wear diagnostic and prognostic by using dynamic Bayesian networks  

NASA Astrophysics Data System (ADS)

The failure of critical components in industrial systems may have negative consequences on the availability, the productivity, the security and the environment. To avoid such situations, the health condition of the physical system, and particularly of its critical components, can be constantly assessed by using the monitoring data to perform on-line system diagnostics and prognostics.The present paper is a contribution on the assessment of the health condition of a computer numerical control (CNC) tool machine and the estimation of its remaining useful life (RUL). The proposed method relies on two main phases: an off-line phase and an on-line phase. During the first phase, the raw data provided by the sensors are processed to extract reliable features. These latter are used as inputs of learning algorithms in order to generate the models that represent the wear's behavior of the cutting tool. Then, in the second phase, which is an assessment one, the constructed models are exploited to identify the tool's current health state, predict its RUL and the associated confidence bounds. The proposed method is applied on a benchmark of condition monitoring data gathered during several cuts of a CNC tool. Simulation results are obtained and discussed at the end of the paper.

Tobon-Mejia, D. A.; Medjaher, K.; Zerhouni, N.

2012-04-01

259

Research on test techniques of fault forewarning and diagnosis for high-end CNC machine tool  

NASA Astrophysics Data System (ADS)

With the progress of modern science and technique, the manufacturing industry becomes more and more complex and intelligent. It is the challenge for stable, safe running and economical efficiency of machining equipment such as high-quality numerical control because of its complex structure and integrated functions, and the potential faults are easy to happen. How to ensure the equipment runs stably and reliably becomes the key problem to improve the machining precision and efficiency. In order to prolong the average no-fault time, stable running and machining precision of numerical control, it is very important to make relative test and research on acquisition of data of numerical control sample and establishment of sample database. Take high-end CNC Machine Tool for example, the research on test techniques for data acquisition of sample of typical functional parts in CNC Machine Tool will be made and test condition will be set up; the test methods for sample acquisition on running state monitoring and fault forewarning and diagnosis of numerical control is determined; the test platform for typical functional parts of numerical control is established; the sample database is designed and the sample base and knowledge mode is made. The test and research provide key test techniques to disclosure dynamic performance of fault and precision degeneration, and analyze the impact factors to fault.

Ren, Bin; Xu, Xiaoli

2010-12-01

260

Performance Evaluation of Multi-Axis CNC Machine Tools by Interferometry Principle using Laser Calibration System  

NASA Astrophysics Data System (ADS)

Advancement in digital electronics and microprocessors has made the manufacturing sector capable to generate complex components within small tolerance zone in nanometre range at one machining center. All motion control systems have some form of position feed back system fitted with the machine. But the systems are not perfectly accurate due to the errors in the positioning performance of the machine tools which will change over time to time due to wear, damage and environmental effect. The complex structure of multi-axis CNC machine tools produces an inaccuracy at the tool tip caused by kinematic parameter deviations resulting in manufacturing errors, assembly error and quasi-static errors. Analysis of these errors using a laser measurement system provides the user with a way to achieve better accuracy, and hence higher quality output from these processes. In this paper, characteristic of the positioning errors of the axes of multi-axis CNC machine tools and the technique to measure the errors by a laser interferometer calibration system have been discussed and the positioning accuracy of the machine each axis has been verified.

Barman, S.; Sen, R.

2012-06-01

261

Mr. R.'s World of Math  

NSDL National Science Digital Library

Mr. R.'s World of Math is a teacher-created collection of math videos, poems, stories, songs, and challenges to help students master basic math functions. In addition to videos there are printable student handouts for the math challenges and several powerpoint demonstrations.

262

New Photometric Observations of RS Oph  

NASA Astrophysics Data System (ADS)

The recurrent nova RS Oph is a long period (~455 days) binary system consisting of a hot white dwarf with mass close to the Chandrasekhar limit and an M-type giant secondary. Here we present the results of photometric observations of this nova which were made during recent years with the telescopes of the Sternberg Astronomical Institute in Crimea.

Voloshina, Irina; Metlov, Vladimir

2013-01-01

263

FPGA-Based Vibration Analyzer for Continuous CNC Machinery Monitoring With Fused FFT-DWT Signal Processing  

Microsoft Academic Search

The industry of machine tools keeps a constant progress that responds to the most demanding market requirements, such as production-time decreasing and zero-defect manufacturing. As part of this progress, sensors and monitoring instruments have been integrated on machine tools, improving computer numerical control (CNC) and monitoring during the manufacturing process. The vibrations are one of the most significant variables to

Jose de Jesus Rangel-Magdaleno; René de Jesús Romero-Troncoso; Roque Alfredo Osornio-Rios; Eduardo Cabal-Yepez; Aurelio Dominguez-Gonzalez

2010-01-01

264

Accuracy test of five-axis CNC machine tool with 3D probe-ball. Part II: errors estimation  

Microsoft Academic Search

To improve the accuracy of CNC machine tools, error sources and its effects on the overall position and orientation errors must be known. Most motional errors in the error model of five-axis machine tool can be measured with modern laser interferometer devices, but there are still some not measurable geometric errors. These not measurable errors include constant, inaccurate link errors

W. T. Lei; Y. Y. Hsu

2002-01-01

265

Discrete Optimization Optimal allocation and processing time decisions on non-identical parallel CNC machines: ? -constraint approach  

Microsoft Academic Search

When the processing times of jobs are controllable, selected processing times affect both the manufacturing cost and the scheduling performance. A well known example for such a case that this paper specifically deals with is the turning oper- ation on a CNC machine. Manufacturing cost of a turning operation is a nonlinear convex function of its processing time. In this

Sinan Gurel; M. Selim Akturk

266

76 FR 39156 - C&NC Railroad, LLC-Lease Renewal Exemption-Norfolk Southern Railway Company  

Federal Register 2010, 2011, 2012, 2013

...FD 35529] C&NC Railroad, LLC--Lease Renewal Exemption--Norfolk Southern...whether to issue notices of exemption for lease transactions under 49 U.S.C. 10902...The Board determines that this notice of lease renewal exemption should be issued,...

2011-07-05

267

Advanced CNC and CAM Series. Educational Resources for the Machine Tool Industry. Course Syllabi, Instructor's Handbook [and] Student Laboratory Manual.  

ERIC Educational Resources Information Center

This package consists of course syllabi, an instructor's handbook, and student laboratory manual for a 1-year vocational training program to prepare students for entry-level positions as advanced computer numerical control (CNC) and computer-assisted manufacturing (CAM) technicians.. The program was developed through a modification of the DACUM…

Texas State Technical Coll. System, Waco.

268

Fuzzy Petri nets with neural networks to model products quality from a CNC-milling machining centre  

Microsoft Academic Search

This paper presents a Petri net approach for the modeling of a CNC-milling machining centre. Next, by utilizing fuzzy logic with Petri nets (fuzzy Petri nets), a technique based on 9 fuzzy rules is developed. This paper demonstrates how fuzzy input variables, fuzzy marking, fuzzy firing sequences, and a global output variable should be defined for use with fuzzy Petri

Moheb M. Hanna; Arthur Buck; Roger Smith

1996-01-01

269

Theoretical and experimental research on machine tool servo system for ultra-precision position compensation on CNC lathe  

Microsoft Academic Search

The theories and techniques for improving machining accuracy via position control of diamond tool's tip and raising resolution of cutting depth on precise CNC lathes have been extremely focused on. A new piezo-driven ultra-precision machine tool servo system is designed and tested to improve manufacturing accuracy of workpiece. The mathematical model of machine tool servo system is established and the

Zhichao Ma; Leilei Hu; Hongwei Zhao; Boda Wu; Zhenxing Peng; Xiaoqin Zhou; Hongguo Zhang; Shuai Zhu; Lifeng Xing; Huang Hu

2010-01-01

270

Accuracy test of five-axis CNC machine tool with 3D probe–ball. Part I: design and modeling  

Microsoft Academic Search

The error model of CNC machine tool describes the relationship between the individual error source and its effects on the overall position errors. A practical problem in applying this technique to five-axis machine tool is that the predicted position errors cannot be justified. This paper, the first in a set of two, presents a new measurement device, the probe–ball, which

W. T. Lei; Y. Y. Hsu

2002-01-01

271

The Use of Patent Data for Technological Forecasting: The Diffusion of CNC-Technology in the Machine Tool Industry  

Microsoft Academic Search

In the 1980s, a dramatic change in the competitive structure of the machine tool industry through the development and implementation of CNC-technology occurred. For the individual company, the timely anticipation and forecast of these technological challenges has been of vital importance in order to incorporate these technological changes into its strategic planning process. This paper assesses the suitability of patent

H. Ernst

1997-01-01

272

Advanced CNC and CAM Series. Educational Resources for the Machine Tool Industry. Course Syllabi, Instructor's Handbook [and] Student Laboratory Manual.  

ERIC Educational Resources Information Center

|This package consists of course syllabi, an instructor's handbook, and student laboratory manual for a 1-year vocational training program to prepare students for entry-level positions as advanced computer numerical control (CNC) and computer-assisted manufacturing (CAM) technicians.. The program was developed through a modification of the DACUM…

Texas State Technical Coll. System, Waco.

273

Development and implementation for real-time lookahead interpolator by using Bezier curve to fit CNC continuous short blocks  

Microsoft Academic Search

This paper describes the analysis of a command generator, i.e. interpolator, used for CNC machine motion control. The lookahead algorithm discussed in this paper involves circular contraction error, corner error and deceleration distance limit; hence, planning of a more rational feedrate profile across a series of blocks is made possible. With a prescribed precision, the feedrate and machining performance can

Hong-Tzong Yau; Jun-Bin Wang; Wen-Chie Chen

2005-01-01

274

Two new ApoB gene polymorphisms: Rs3 and Rs4  

SciTech Connect

2.0 kb fragment intestinal cDNA clone I subcloned in pUC18. RsaI digests identifies 7 fragments: 2.2, 2.0, 1.4, 1.2, 0.7, and 0.6 and 0.4 kb, spanning 12 kb of the ApoB gene. RsaI RFLP Rs3 detected at 1.6 kb and Rs4 at 2.4 kb. It was located on 2p23-24 by in-situ hybridization. 1.3 kb SstI fragment of I (2) 1 localizes Rs3 near exon 26. Rs4 similarly localizes near exon 26.

Genest, J.J. Jr.; Ordovas, J.M.; Robbins, A.H.; King, D.C.; Frossard, P.M.; Schaefer, E.J. (Tufts Univ., Mountain View, CA (USA))

1988-09-12

275

The relation between RS CVn and Algol  

Microsoft Academic Search

Late-type secondaries in Algol binaries are rapidly rotating convective stars and thus should be chromospherically active (CA). They are examined with respect to observational manifestations which characterize already known CA stars: Ca II H and K emission cores, photometric variability attributable to starspots, soft x-ray emission, non-thermal radio emission, ultraviolet and infrared excess, and alternating period changes. The conclusion is

Douglas S. Hall

1989-01-01

276

Symbiotic Stars  

NASA Astrophysics Data System (ADS)

During the production of the Henry Draper Catalog, Wilhemina Fleming identified several M-type stars with unusually strong hydrogen emission lines. Paul Merrill obtained higher quality spectra of these `stars with combination spectra' and found intense emission from He II or [O III] and [Ne III] in addition to H I. All of these stars varied by 0.5-1 mag on a timescale of several years. A few syst...

Kenyon, S.; Murdin, P.

2000-11-01

277

Sea Stars  

NSDL National Science Digital Library

At first glance, starfish, more properly called sea stars, arenât doing much of anything. In this video, Jonathanâs investigations reveal a slow-motion predator that hunts and attacks its prey. Traveling the world, Jonathan investigates sea stars from the tropics to the Antarctic and uses time-lapse photography to reveal an amazing complexity to the world of the sea star. Please see the accompanying study guide for educational objectives and discussion points.

Productions, Jonathan B.

2010-10-06

278

X-ray spectra and the rotation-activity connection of RS Canum Venaticorum binaries  

SciTech Connect

Results are presented from a survey of RS CVn binaries which were observed with the imaging proportional counter (IPC) on board the Einstein Observatory. Spectral analyses of the IPC pulse height spectra show that the coronae of RS CVn binaries always contain hot gas with temperatures in excess of 10 to the 7th K, similar to active late-type main-sequence stars, and that at least two temperature components are necessary to account for the higher quality IPC spectra (when absorption is unimportant). It is argued that these bimodal temperature distributions found by the IPC are indicative of true distributions of emission measure versus temperature that are continuous (just as is the case of magnetically confined coronal plasma loops observed on the sun). It is further shown that none of the derivable x-ray characteristics of RS CVn binaries depend on rotation period, implying that previous claims of period-activity relationships in RS CVn binaries were unfounded. 44 references.

Majer, P.; Schmitt, J.H.M.M.; Golub, L.; Harnden, F.R.,JR.; Rosner, R.

1986-01-01

279

Lucky Star  

NSDL National Science Digital Library

Watch this video from Cyberchase and then play the Lucky Star game! The Lucky Star game show the will ask you math-related questions and give you four possible answers to choose from. Your goal is to answer the questions correctly and score as many points as you can. You can score points during two different rounds: the pick-a-star round and the lightning round. During the pick-a-star round you have as much time as you want to answer the questions. During the lightning round you have to think fast in order to earn the points. Good luck!

2008-01-01

280

RS1, custodial isospin and precision tests  

NASA Astrophysics Data System (ADS)

We study precision electroweak constraints within a RS1 model with gauge fields and fermions in the bulk. The electroweak gauge symmetry is enhanced to SU(2)L × SU(2)R × U(1)B-L, thereby providing a custodial isospin symmetry sufficient to suppress excessive contributions to the T parameter. We then construct complete models, complying with all electroweak constraints, for solving the hierarchy problem, without supersymmetry or large hierarchies in the fundamental couplings. Using the AdS/CFT correspondence our models can be interpreted as dual to a strongly coupled conformal Higgs sector with global custodial isospin symmetry, gauge and fermionic matter being fundamental fields external to the CFT. This scenario has interesting collider signals, distinct from other RS models in the literature.

Agashe, Kaustubh; Delgado, Antonio; May, Michael J.; Sundrum, Raman

2003-08-01

281

Exercise-Induced RS-T Elevation  

Microsoft Academic Search

In 4 patients in which an exercise test induced an elevation of the RS-T segment and an increase of the R-wave, coronary angiography showed a localized, subocclusive stenosis of the single major coronary vessel supplying the myocardial area responsible for the electrocardiographic alterations. This observation demonstrates the value of the exercise test in evoking electrocardiographic features often associated with Prinzmetal’s

P. Bobba; C. Vecchio; L. Di Guglielmo; J. Salerno; A. Casari; C. Montemartini

1972-01-01

282

Association of BLK (rs13277113, rs2248932) polymorphism with systemic lupus erythematosus: a meta-analysis.  

PubMed

The B-cell lymphocyte kinase (BLK) is a src-family protein tyrosine kinase specifically expressed in B-lineage cells that has been implicated in the pathogenesis of systemic lupus erythematosus (SLE) and has been investigated in numerous ethnically diverse studies. However, genetic association studies that have examined the association between BLK gene variants and SLE have produced conflicting results. To shed further light on this issue, we performed a meta-analysis of the association between rs13277113, rs2248932 polymorphism and SLE in different ethnic groups. An updated literature-based meta-analysis of six original articles involving 20,271 control individuals and 11,796 subjects with SLE was conducted. Crude ORs with 95% CIs were used to assess the strength of association between rs13277113, rs2248932 polymorphism and SLE risk. Publication bias was estimated using Egger's linear regression test. The authors assessed the evidence of genotypic association using STATA Version 10.0. The combined overall odds ratio, calculated for SLE and the risk A-allele of rs13277113 was 1.416 (95% CI: 1.358, 1.477). An odds ratio of 1.264 (95% CI: 1.208, 1.322) was found for the T-allele of rs2248932. Significant associations of rs13277113 and SLE were observed for dominant model (AA + AG vs. GG, OR: 1.518; 95% CI: 1.411, 1.632), and recessive model (AA vs. AG + GG, OR: 1.553; 95% CI: 1.461, 1.651); so were rs2248932 and SLE for dominant model (TT + TC vs. CC, OR: 1.342; 95% CI: 1.233, 1.460), and recessive model (TT vs. TC + CC, OR: 1.338; 95% CI: 1.257, 1.424). All of these were conducted in fixed effects model as heterogeneity was not detected. Tests for bias revealed no evidence of biases. On the assessment of available evidence, the authors concluded that moderate evidence exists for an association between the BLK rs13277113, rs2248932 variants and SLE. Therefore, further research is warranted on the role of BLK polymorphisms in the etiology of SLE. PMID:21152986

Fan, Ye; Tao, Jin-Hui; Zhang, Li-Ping; Li, Lian-Hong; Ye, Dong-Qing

2010-12-09

283

An Analysis of Light Variations of RS Canum Venaticorum Binary Systems.  

NASA Astrophysics Data System (ADS)

Photoelectric data for fourteen RS Canum Venaticorum binary systems were obtained by the author from 1978 through 1981, at Rosemary Hill Observatory. These data are presented in the form of light curves and tabulated magnitudes and heliocentric Julian Dates. The outside-of-eclipse points for eight systems were Fourier analyzed for measurement of any distortion wave in the light curve. The wave in RS Canum Venaticorum itself was found to have moved half a phase unit in only two years. A wave was discovered in the light curve of RZ Eridani, and was found to have changed in a manner consistent with the starspot model for RS CVn systems. The light curve for UX Comae Bernices was found to have a large amount of intrinsic scatter, and the system was found to be anomalously bright on one night. These characteristics suggest that some type of flare activity may be present in that system. The other five systems analyzed were found to have waves consistent with other published results, or to have no definite wave at all. The possibility of detecting spots and deriving spot sizes from secondary eclipse observations was also explored. For this purpose the Wilson-Devinney computer program for light curve synthesis was modified to allow spots on the secondary star. Comparison of computer synthesized secondary eclipses of spotted stars to actual observations showed that there is little chance of detecting fluctuations due to individual spots. It was found that there is even less chance for discriminating between a few large spots and a large number of smaller spots. However, the program did produce good fits to RS CVn light curves, using reasonable spot parameters.

Caton, Daniel Bruce

284

Compact Stars  

NASA Astrophysics Data System (ADS)

Neutron stars are the smallest denses stars known, with densities some 1014 times that of the Earth. They rotate with periods of fractions of a second, and their magnetic fields drive intense interstellar dynamos, lighting up entire nebulae. This text discusses the physics of these extreme objects. It includes the needed background in classical general relativity in nuclear and particle physics.

Glendenning, Norman K.

285

Rogue Star  

NSDL National Science Digital Library

This program calculates and depicts the effects of a rogue star coming through our solar system. Users adjust the date, the rogue star's mass, approach distance in astronomical units (AU) and flyby speed to run an animation of what would happen to the planets under the specified conditions.

Hamilton, Douglas

286

Star Journey  

NSDL National Science Digital Library

This National Geographic web-site contains information about the Hubble Space Telescope (HST) along with a star chart and facts about objects in the night sky. The HST section contains details about the building and structure of the HST, how it captures light, positioning the HST to targets, instruments used to record and measure infrared through UV wavelengths, how the HST is powered and communicates with the Earth. Star Attractions discusses properties of constellations, the Milky Way galaxy, other galaxies, star clusters and nebulae. This information is then put together on the National Geographic Star Chart. This chart contains maps of the heavens for the northern and southern hemispheres. The chart contains constellation names, location of stars and other objects, and links to HST images of various galaxies and objects on the chart with names and detailed descriptions. There is an image index to find HST images from the site, details about chart symbol meanings, and links for more information.

Anderson, Carolyn

287

Frequent Phosphodiesterase 11A Gene (PDE11A) Defects in Patients with Carney Complex (CNC) Caused by PRKAR1A Mutations: PDE11A May Contribute to Adrenal and Testicular Tumors in CNC as a Modifier of the Phenotype  

PubMed Central

Background: Carney complex (CNC) is an autosomal dominant multiple neoplasia, caused mostly by inactivating mutations of the regulatory subunit 1A of the protein kinase A (PRKAR1A). Primary pigmented nodular adrenocortical disease (PPNAD) is the most frequent endocrine manifestation of CNC with a great inter-individual variability. Germline, protein-truncating mutations of phosphodiesterase type 11A (PDE11A) have been described to predispose to a variety of endocrine tumors, including adrenal and testicular tumors. Objectives: Our objective was to investigate the role of PDE11A as a possible gene modifier of the phenotype in a series of 150 patients with CNC. Results: A higher frequency of PDE11A variants in patients with CNC compared with healthy controls was found (25.3 vs. 6.8%, P < 0.0001). Among CNC patients, those with PPNAD were significantly more frequently carriers of PDE11A variants compared with patients without PPNAD (30.8 vs. 13%, P = 0.025). Furthermore, men with PPNAD were significantly more frequently carriers of PDE11A sequence variants (40.7%) than women with PPNAD (27.3%) (P < 0.001). A higher frequency of PDE11A sequence variants was also found in patients with large-cell calcifying Sertoli cell tumors (LCCSCT) compared with those without LCCSCT (50 vs. 10%, P = 0.0056). PDE11A variants were significantly associated with the copresence of PPNAD and LCCSCT in men: 81 vs. 20%, P < 0.004). The simultaneous inactivation of PRKAR1A and PDE11A by small inhibitory RNA led to an increase in cAMP-regulatory element-mediated transcriptional activity under basal conditions and after stimulation by forskolin. Conclusions: We demonstrate, in a large cohort of CNC patients, a high frequency of PDE11A variants, suggesting that PDE11A is a genetic modifying factor for the development of testicular and adrenal tumors in patients with germline PRKAR1A mutation.

Libe, Rossella; Horvath, Anelia; Vezzosi, Delphine; Fratticci, Amato; Coste, Joel; Perlemoine, Karine; Ragazzon, Bruno; Guillaud-Bataille, Marine; Groussin, Lionel; Clauser, Eric; Raffin-Sanson, Marie-Laure; Siegel, Jennifer; Moran, Jason; Drori-Herishanu, Limor; Faucz, Fabio Rueda; Lodish, Maya; Nesterova, Maria; Bertagna, Xavier; Bertherat, Jerome; Stratakis, Constantine A.

2011-01-01

288

40 CFR 180.1114 - Pseudomonas fluorescens A506, Pseudomonas fluorescens 1629RS, and Pseudomonas syringae 742RS...  

Code of Federal Regulations, 2010 CFR

40 Protection of Environment 23 2010-07-01 2010-07-01 false Pseudomonas fluorescens A506, Pseudomonas fluorescens 1629RS, and Pseudomonas syringae 742RS; exemptions from the requirement of a tolerance. 180.1114...

2010-07-01

289

40 CFR 180.1114 - Pseudomonas fluorescens A506, Pseudomonas fluorescens 1629RS, and Pseudomonas syringae 742RS...  

Code of Federal Regulations, 2010 CFR

40 Protection of Environment 23 2009-07-01 2009-07-01 false Pseudomonas fluorescens A506, Pseudomonas fluorescens 1629RS, and Pseudomonas syringae 742RS; exemptions from the requirement of a tolerance. 180.1114...

2009-07-01

290

A catalog of chromospherically active binary stars  

NASA Astrophysics Data System (ADS)

The authors have compiled a catalog of 168 chromospherically active binary stars including the class of RS Canum Venaticorum binaries, BY Draconis binaries and other binaries which show "strong" Ca II H and K emission in their spectra. The catalog contains information on the photometric, spectroscopic, orbital and physical properties of the systems as well as the space motions and positions. Summarized in a candidate list are an additional 37 stars having similar characteristics but which are not definitely known binaries or have not had H and K emission observed. A bibliography and notes for each star are included to direct interested workers to primary references for each of the systems. The catalog contains stars in both the northern and the southern sky.

Strassmeier, K. G.; Hall, D. S.; Zeilik, M.; Nelson, E.; Eker, Z.; Fekel, F. C.

1988-02-01

291

Phylogeny and distribution of extra-slow-growing Bradyrhizobium japonicum harboring high copy numbers of RS?, RS? and IS 1631  

Microsoft Academic Search

We previously reported that extra-slow-growing Bradyrhizobium japonicum isolates obtained from three field sites in Japan, designated as HRS (highly reiterated sequence-possessing) strains, have high copy numbers of the insertion sequences RS? and RS?. When strain collections in the USA, Japan, Korea, Thailand and China were examined by Southern hybridization using RS?, RS? and IS1631 as probes, HRS strains were found

Reiko Sameshima; Tsuyoshi Isawa; Michael J. Sadowsky; Tohru Hamada; Hiroaki Kasai; Arawan Shutsrirung; Hisayuki Mitsui; Kiwamu Minamisawa

2003-01-01

292

A novel CNC grinding method for the rake face of a taper ball-end mill with a CBN spherical grinding wheel  

Microsoft Academic Search

A novel method using a CBN spherical grinding wheel to grind the rake face of a taper ball-end mill and the configuration\\u000a of corresponding CNC tool grinder are presented. This method utilizes the self-adaptation characteristics of a sphere to decrease\\u000a the number of simultaneous cooperative axes of a CNC tool grinder and to smooth the rake face on the transition

Fang Chen; Hongzan Bin

2009-01-01

293

The ROSAT All-Sky Survey of active binary coronae. I - Quiescent fluxes for the RS Canum Venaticorum systems  

NASA Astrophysics Data System (ADS)

One hundred and thirty-six RS CV(n) active binary systems were observed with the ROSAT Position Sensitive Proportional Counter (PSPC) during the All-Sky Survey component of the mission. The entire sky was surveyed, which represents the largest sample of RS CV(n) systems observed to date at any wavelength, including X-rays. X-ray surface fluxes for the RS CV(n) systems are found to lie in the range 10 exp 4 to 10 exp 8 ergs/sq cm seconds. Surface flux as a function of (B - V) color is reported. A decrease in surface flux with increasing rotation period for the entire sample is observed. The rotation period provides the best stellar or orbital parameter to predict the X-ray surface flux level. The absence of correlation of F(x) or L(x) with Gamma is noted due to the fact that the coronal heating mechanism for these active stars must be magnetic in character, and the magnetic field depends on the interaction between convection and differential rotation inside the star. X-ray properties of the RS CV(n) systems with 6 cm radio and C IV UV emission systems is compared.

Dempsey, Robert C.; Linsky, Jeffrey L.; Fleming, Thomas A.; Schmitt, J. H. M. M.

1993-06-01

294

Enigmatic star EZ Pegasi - a mystery solved  

SciTech Connect

EZ Peg, a ninth-magnitude G star that has been classified by various authors as an irregular variable, a U Gem system, and a contact binary, is shown to have all the spectroscopic and photometric characteristics of an active-chromosphere RS CVn binary. It is suggested that the reported outburst of 1943, when the spectrum appeared to be that of a B star, never occurred. The strong Ca II H and K reversals, viewed with low spectral resolution, caused the photospheric Ca II absorption to appear abnormally weak, mimicking a much earlier spectral type. 20 references.

Howell, S.B.; Bopp, B.W.

1985-01-01

295

VEGF A (rs699947 and rs833061) and VEGFR2 (rs2071559) Gene Polymorphisms are not Associated with AMD Susceptibility in a Spanish Population.  

PubMed

Abstract Purpose: Age-related macular degeneration (AMD) is a multifactorial disease due to interaction between genetic and environmental factors. Increased angiogenesis plays a central role in AMD development. Previous studies on the potential link between AMD and vascular endothelial growth factor (VEGFA) and vascular endothelial growth factor receptor (VEGFR) have yielded conflicting results. We have analysed if polymorphisms in genes coding for VEGFA and VEGFR are associated to susceptibility to suffer AMD in a cohort of Spanish subjects. Patients and Methods: We obtained peripheral blood samples from 151 patients with diagnosis of exudative AMD. We also studied 91 healthy subjects matched by age. We studied VEGFA rs699947 and rs833061, and VEGFR2 rs2071559 polymorphisms using real-time PCR with TaqMan probes. Results: We did not find statistically significant differences in genotypic distribution of VEGF rs699947 and rs833061 polymorphisms between patients and controls. However, analysis of VEGFR2 rs2071559 polymorphism shows that carriers of GG genotype are more frequent in subjects with AMD (p: 0.032; Odds Ratio(OR): 1.933; confidence interval (CI): 1.053-3.549), but, when corrected by Bonferroni testing, the result was found to be not significant. Conclusion: Our study shows that VEGFA rs699947 and rs833061 and VEGFR2 rs2071559 polymorphisms do not modify the risk of suffering AMD in a Spanish population. PMID:23971975

Cruz-González, Fernando; Cieza-Borrella, Clara; Cabrillo-Estévez, L; Cañete-Campos, Cristina; Escudero-Domínguez, Francisco; González-Sarmiento, Rogelio

2013-08-23

296

Activity Cycles in Stars with Highly Active Chromospheres  

Microsoft Academic Search

We propose to continue IUE observations of the highly active RS CVn Binaries V711 Tauri, Lambda Andromedae, II Peg, and UX Arietis and the rapidly-rotating early-G giant FK Comae. These stars have the most extensive IUE archival coverage for stars of this type and have almost continuous ground-based photometric coverage from about 1975 onward. We aim to trace the long-term

Edward F. Guinan

1991-01-01

297

The NOD2 Single Nucleotide Polymorphisms rs2066843 and rs2076756 Are Novel and Common Crohn's Disease Susceptibility Gene Variants  

PubMed Central

Background The aims were to analyze two novel NOD2 variants (rs2066843 and rs2076756) in a large cohort of patients with inflammatory bowel disease and to elucidate phenotypic consequences. Methodology/Principal Findings Genomic DNA from 2700 Caucasians including 812 patients with Crohn's disease (CD), 442 patients with ulcerative colitis (UC), and 1446 healthy controls was analyzed for the NOD2 SNPs rs2066843 and rs2076756 and the three main CD-associated NOD2 variants p.Arg702Trp (rs2066844), p.Gly908Arg (rs2066847), and p.Leu1007fsX1008 (rs2066847). Haplotype and genotype-phenotype analyses were performed. The SNPs rs2066843 (p?=?3.01×10?5, OR 1.48, [95% CI 1.23-1.78]) and rs2076756 (p?=?4.01×10?6; OR 1.54, [95% CI 1.28-1.86]) were significantly associated with CD but not with UC susceptibility. Haplotype analysis revealed a number of significant associations with CD susceptibility with omnibus p values <10?10. The SNPs rs2066843 and rs2076756 were in linkage disequilibrium with each other and with the three main CD-associated NOD2 mutations (D'>0.9). However, in CD, SNPs rs2066843 and rs2076756 were more frequently observed than the other three common NOD2 mutations (minor allele frequencies for rs2066843 and rs2076756: 0.390 and 0.380, respectively). In CD patients homozygous for these novel NOD2 variants, genotype-phenotype analysis revealed higher rates of a penetrating phenotype (rs2076756: p?=?0.015) and fistulas (rs2076756: p?=?0.015) and significant associations with CD-related surgery (rs2076756: p?=?0.003; rs2066843: p?=?0.015). However, in multivariate analysis only disease localization (p<2×10?16) and behaviour (p?=?0.02) were significantly associated with the need for surgery. Conclusion/Significance The NOD2 variants rs2066843 and rs2076756 are novel and common CD susceptibility gene variants.

Tillack, Cornelia; Pfennig, Simone; Beigel, Florian; Jurgens, Matthias; Olszak, Torsten; Laubender, Rudiger P.; Weidinger, Maria; Muller-Myhsok, Bertram; Goke, Burkhard; Ochsenkuhn, Thomas; Lohse, Peter; Diegelmann, Julia; Czamara, Darina; Brand, Stephan

2010-01-01

298

Interferometer observations of RS Canum Venaticorum binaries  

NASA Astrophysics Data System (ADS)

We present radio flux measurements at 5 GHz for a sample of RS CVn-type chromospherically active binary systems made from 1988 to 1992 using the Nuffield Radio Astronomy Laboratories (NRAL) broad-band interferometer (BBI). The derived radio luminosities are consistent with previous observations but show that radio flaring is a common feature which will effect the results of rotation-activity studies. The mean brightness temperature for our sample, assuming a radio source size equal to twice the radius of the active stellar component, is consistent with a gyrosynchrotron emission process from mildly relativistic electrons.

Gunn, A. G.; Spencer, R. E.; Abdul Aziz, H.; Doyle, J. G.; Davis, R. J.; Pavelin, P. E.

1994-11-01

299

A novel RS BTC coding scheme for optical communications  

NASA Astrophysics Data System (ADS)

A novel Reed Solomon (RS) block turbo code (BTC) coding scheme of RS(63,58)×RS(63,58) for optical communications is proposed. The simulation results show that the net coding gain (NCG) of this scheme at the sixth iteration is more than that of other coding schemes at the third iteration for the bit error rate (BER) of 10-12. Furthermore, the novel RS BTC has shorter component code and rapider encoding and decoding speed. Therefore, the novel RS BTC coding scheme can be better used in high-speed long-haul optical communication systems, and the novel RS BTC can be regarded as a candidate code of the super forward error correction (super-FEC) code. Moreover, the encoding/decoding design and implementation of the novel RS BTC are also presented

Yuan, Jian-guo; Jia, Yue-xing; Hu, Yun-xia

2012-07-01

300

55 CANCRI: A COPLANAR PLANETARY SYSTEM THAT IS LIKELY MISALIGNED WITH ITS STAR  

SciTech Connect

Although the 55 Cnc system contains multiple, closely packed planets that are presumably in a coplanar configuration, we use numerical simulations to demonstrate that they are likely to be highly inclined to their parent star's spin axis. Due to perturbations from its distant binary companion, this planetary system precesses like a rigid body about its parent star. Consequently, the parent star's spin axis and the planetary orbit normal likely diverged long ago. Because only the projected separation of the binary is known, we study this effect statistically, assuming an isotropic distribution for wide binary orbits. We find that the most likely projected spin-orbit angle is {approx}50 Degree-Sign , with a {approx}30% chance of a retrograde configuration. Transit observations of the innermost planet-55 Cnc e-may be used to verify these findings via the Rossiter-McLaughlin effect. 55 Cancri may thus represent a new class of planetary systems with well-ordered, coplanar orbits that are inclined with respect to the stellar equator.

Kaib, Nathan A.; Duncan, Martin J. [Department of Physics, Queen's University, Kingston, ON K7L 3N6 (Canada); Raymond, Sean N., E-mail: nkaib@astro.queensu.ca [Universite de Bordeaux, Observatoire Aquitain des Sciences de l'Univers, 2 rue de l'Observatoire, BP 89 33271 Floirac Cedex (France)

2011-12-15

301

Spectroscopy of Nine Cataclysmic Variable Stars  

NASA Astrophysics Data System (ADS)

We present optical spectroscopy of nine cataclysmic binary stars, mostly dwarf novae, obtained primarily to determine orbital periods Porb. The stars and their periods are LX And, 0.1509743(5) days; CZ Aql, 0.2005(6) days; LU Cam, 0.1499686(4) days; GZ Cnc, 0.0881(4) days; V632 Cyg, 0.06377(8) days; V1006 Cyg, 0.09903(9) days; BF Eri, 0.2708804(4) days; BI Ori, 0.1915(5) days; and FO Per, for which Porb is either 0.1467(4) or 0.1719(5) days. Several of the stars proved to be especially interesting. In BF Eri, we detect the absorption spectrum of a secondary star of spectral type K3 +/- 1 subclass, which leads to a distance estimate of ~1 kpc. However, BF Eri has a large proper motion (~100 mas yr-1), and we have a preliminary parallax measurement that confirms the large proper motion and yields only an upper limit for the parallax. BF Eri's space velocity is evidently large, and it appears to belong to the halo population. In CZ Aql, the emission lines have strong wings that move with large velocity amplitude, suggesting a magnetically channeled accretion flow. The orbital period of V1006 Cyg places it squarely within the 2 to 3 hr ``gap'' in the distribution of cataclysmic binary orbital periods. Based on observations obtained at the MDM Observatory, operated by Dartmouth College, Columbia University, Ohio State University, Ohio University, and the University of Michigan.

Sheets, Holly A.; Thorstensen, John R.; Peters, Christopher J.; Kapusta, Ann B.; Taylor, Cynthia J.

2007-05-01

302

Stars equilibrium  

NSDL National Science Digital Library

What causes the fusion reaction in a star's core? This activity page, part of an interactive laboratory series for grades 8-12, introduces students to processes inside a star. Students read about the equilibrium process in a star, in which outward gas pressure equals inward gravitational pressure. Then, an interactive lab activity offers students the opportunity to predict temperature, pressure, and gravity changes that occur during equilibrium. The chemical reactions of the fusion process are presented, and more specific detailed reactions are available in a pop-up box. Student practice quizzes about the equilibrium process and pressure and gravity interactions inside the star are included, as are answers. Copyright 2005 Eisenhower National Clearinghouse

University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

2003-01-01

303

The S-process nucleosynthesis of zirconium in S-stars  

NASA Astrophysics Data System (ADS)

The abundances of 90,91,92,93,94Zr in the S stars R Cyg, V Cnc, and R Gem as reported by Zook (1978) are studied using the model of an exponential distribution of neutron exposures. The characteristic quantity, the average time integrated neutron flux ?0, was determined to be (0.075+0.083-0.029) 1027 neutrons per cm2. The neutron density was estimated to be smaller than ?108 neutrons per cm3 due to the absence of any 96Zr abundance. Implications for the pulsed s-process model of Truran and Iben (1977) are discussed.

Beer, H.; Walter, G.

1984-04-01

304

Allelic clustering and ancestry-dependent frequencies of rs6232, rs6234, and rs6235 PCSK1 SNPs in a Northern Ontario population sample.  

PubMed

The PCSK1 (proprotein convertase subtilisin/kexin type 1) locus encodes proprotein convertase 1/3, an endoprotease that converts prohormones and proneuropeptides to their active forms. Spontaneous loss-of-function mutations in the coding sequence of its gene have been linked to obesity in humans. Minor alleles of two common non-synonymous single-nucleotide polymorphisms (SNPs), rs6232 (T?>?C, N221D) and rs6235 (C?>?G, S690T), have been associated with increased risk of obesity in European populations. In this study, we compared the frequencies of the rs6232 and rs6234 (G?>?C, Q665E) SNPs in Aboriginal and Caucasian populations of Northern Ontario. The two SNPs were all relatively less frequent in Aboriginals: The minor allele frequency of the rs6232 SNP was 0.01 in Aboriginals and 0.08 in Caucasians (P?rs6234 SNP, it was 0.20 and 0.32, respectively (P?rs6234 SNP variation was tightly linked to that of the rs6235 SNP, as previously reported. Most interestingly, all carriers of the rs6232 SNP variation also carried the rs6234/rs6235 SNP clustered variations, but not the reverse, suggesting the former occurred later on an allele already carrying the latter. These data indicate that, in Northern Ontario Aboriginals, the triple-variant PCSK1 allele is relatively rare and might be of lesser significance for obesity risk in this population. PMID:22307923

Sirois, Francine; Kaefer, Nadine; Currie, Krista A; Chrétien, Michel; Nkongolo, Kabwe K; Mbikay, Majambu

2012-02-04

305

The 2006 Outburst of RS Ophiuchi  

NASA Astrophysics Data System (ADS)

We present X-ray observations of the recurrent nova RS Ophiuchi in outburst, obtained with the Chandra and XMM-Newton observatories on six different dates post discovery. An important goal of the observations was to study the central UEV-supersoft X-ray source. X-ray grating spectra are the best way to place constraints on the physical parameters of the white dwarfs in these systems. In the first month after the outburst, we detected emission lines of H and He -like ions of metals including Si, Mg and Ne. The presence of these lines indicates a range of plasma temperatures, and most likely we were detecting emission from red giant wind material shocked by the nova ejecta. Later spectra show a large increase in emission at longer wavelengths, peaking two months after the outburst. We attribute this to the emergence of the underlying white dwarf. We used NLTE white dwarf atmosphere models to fit the spectra, finding log g = 9, and T ˜800,000K. This indicates a white dwarf mass of >1.2 M?). We also present a preliminary timing analysis of the XMM-Newton light curves. We find a period of ˜ 35 s both in March and April. Although the origin of this period is still a question for debate, it may be the spin period of the white dwarf. If this is the case, the white dwarf must again be very massive, making RS Ophiuchi a likely supernova Ia progenitor.

Nelson, Thomas; Orio, Marina; Leibowitz, Elia; Gonzales-Riestra, Rosario; Mucciarelli, Paola

2007-07-01

306

High-Speed RaPToRS  

NASA Astrophysics Data System (ADS)

The High-Speed Rapid Pneumatic Transport of Radioactive Samples (HS-RaPToRS) system, designed to quickly and safely move radioactive materials, was assembled and tested at the Mercury facility of the Naval Research Laboratory (NRL) in Washington D.C. A sample, which is placed inside a four-inch-diameter carrier, is activated before being transported through a PVC tube via airflow. The carrier travels from the reaction chamber to the end station where it pneumatically brakes prior to the gate. A magnetic latch releases the gate when the carrier arrives and comes to rest. The airflow, optical carrier-monitoring devices, and end gate are controlled manually or automatically with LabView software. The installation and testing of the RaPToRS system at NRL was successfully completed with transport times of less than 3 seconds. The speed of the carrier averaged 16 m/s. Prospective facilities for similar systems include the Laboratory for Laser Energetics and the National Ignition Facility.

Henchen, Robert; Esham, Benjamin; Becker, William; Pogozelski, Edward; Padalino, Stephen; Sangster, Thomas; Glebov, Vladimir

2008-11-01

307

Research on multi-robot open architecture of an intelligent CNC system based on parameter-driven technology  

Microsoft Academic Search

This paper presents a multi-robot open architecture of an intelligent computer numerical control (CNC) system based on parameter-driven technology that has been developed for flexible and high-efficiency manipulation. An open architecture control system capable of distributed processing of decision-making and extraction of task information provides a premise for intelligent control and flexible operation. Intelligent detection with database feedback based on

Weike Song; Gang Wang; Juliang Xiao; Guodong Wang; Ying Hong

308

Closed-loop CAPP\\/CAM\\/CNC process chain based on STEPand STEP-NC inspection tasks  

Microsoft Academic Search

The object-oriented STEP-NC programming interface supports a bi-directional data exchange between computer-aided manufacturing (CAM) systems and computerized numerical controllers (CNCs), and by that helps to integrate the CNC into the CAx (Computer Aided technologies in general) world. In this context the current paper introduces the integration of measuring technology into the STEP-NC-based process chain, to be able to preserve the

C. Brecher; M. Vitr; J. Wolf

2006-01-01

309

A real-time high-precision interpolation algorithm for general-typed parametric curves in CNC machine tools  

Microsoft Academic Search

The machining accuracy of computer numerical control (CNC) machine tools largely depends on the interpolation algorithms implemented. In this paper, a real-time high-precision interpolation algorithm for a general-typed parametric curve is proposed. As with other time-partition interpolation algorithms, the linear motion trajectory (employed to approximate the real trajectory) in a sampling cycle is determined from the current position of the

Q. Liu; X. J. Jin; Y. H. Long

2010-01-01

310

Development of a 3-axis desktop milling machine and a CNC system using advanced modern control algorithms  

Microsoft Academic Search

In this paper, we introduce a desktop-size 3-axis milling machine and a CNC system which was developed to operate the 3-axis\\u000a milling machine. The 3-axis milling machine has a mini-desktop size of 200×300×200 mm3 and its cutting volume is 20×20×20 mm3. The vertically installed XY stage is driven by voice-coil motors, and for the zaxis, a magnetically preloaded air bearing

Byung-Sub Kim; Seung-Kook Ro; Jong-Kweon Park

2010-01-01

311

Neutron Stars and Quark Stars  

NASA Astrophysics Data System (ADS)

The tremendous densities reached in the centers of neutron stars provide a high pressure environment in which exciting particles processes are likely compete with each other and novel phases of matter may exist. The particle processes range from the generation of hyperons, to quark deconfinement, to the formation of kaon condensates and H-matter. Another striking possibility concerns the formation of absolutely stable strange quark matter. In the latter event all neutron stars could in fact be strange (quark matter) stars, which would be largely composed of pure quark matter possibly enveloped in a thin nuclear crust made up ordinary hadronic matter. This paper gives an overview of the properties of both classes of stars.

Weber, Fridolin

2004-08-01

312

An X-ray-emitting blast wave from the recurrent nova RS Ophiuchi.  

PubMed

Stellar explosions such as novae and supernovae produce most of the heavy elements in the Universe. The onset of a nova is well understood as driven by runaway thermonuclear fusion reactions on the surface of a white dwarf in a binary star system; but the structure, dynamics and mass of the ejecta are not well known. In rare cases, the white dwarf is embedded in the wind nebula of a red-giant companion, and the explosion products plough through the nebula and produce X-ray emission. Here we report X-ray observations of such an event, from the eruption of the recurrent nova RS Ophiuchi. The hard X-ray emission from RS Ophiuchi early in the eruption emanates from behind a blast wave, or outward-moving shock wave, that expanded freely for less than 2 days and then decelerated owing to interaction with the nebula. The X-rays faded rapidly, suggesting that the blast wave deviates from the standard spherical shell structure. The early onset of deceleration indicates that the ejected shell had a low mass, the white dwarf has a high mass, and that RS Ophiuchi is therefore a progenitor of the type of supernova (type Ia) integral to studies of the expansion of the Universe. PMID:16855584

Sokoloski, J L; Luna, G J M; Mukai, K; Kenyon, Scott J

2006-07-20

313

A study of short-period RS Canum Venaticorum and W Ursae Majoris binary systems - The global nature of H-alpha  

NASA Astrophysics Data System (ADS)

The author presents the rotation versus emission characteristics of the H? line for several short-period (P ? 1d) RS CVn and W UMa binary systems. Estimates for the chromospheric emission arising from each component star were obtained by subtraction of "nonactive" model spectra constructed from comparison stars. Enhanced H? emission compared to the nonactive comparison stars is seen on all components of the short-period RS CVn systems studied, while a similar enhancement is only typically seen on the primary components of the W-type W UMa systems. A possible correlation between LHα/Lbol and the Rossby number (the ratio between the rotational period and the convective time scale) is seen for those components showing emission.

Barden, S. C.

1985-08-01

314

Activity in X-ray-selected late-type stars  

SciTech Connect

A spectroscopic study has been conducted of nine X-ray bright late-type stars selected from two Einstein X-ray surveys: the Columbia Astrophysical Laboratory Survey (five stars) and the CFA Medium Sensitivity Survey (MSS; four stars). Spectral classes were determined and radial and V sin(i) velocities were measured for the stars. Four of the Columbia Survey stars were found to be new RS CVn-type binaries. The fifth Columbia survey star was found to be an active G dwarf star without evidence for binarity. None of the four MSS stars were found to be either binaries or optically active stars. Activity in these stars was assessed by measuring the excess emission in H-alpha and the Ca II IRT (8498, 8542) lines in comparison with inactive stars of similar spectral types. A correlation was found between X-ray luminosity and V sin(i) and H-alpha line excess. The measured excess line emission in H-alpha was also correlated with V sin(i) but not with the IRT line excess. 36 references.

Takalo, L.O.; Nousek, J.A.

1988-03-01

315

Common Proper Motion Companions to Nearby Stars: Ages and Evolution  

NASA Astrophysics Data System (ADS)

A set of 41 nearby stars (closer than 25 pc) is investigated which have very wide binary and common proper motion (CPM) companions at projected separations between 1000 and 200,000 AU. These companions are identified by astrometric positions and proper motions from the NOMAD catalog. Based mainly on measures of chromospheric and X-ray activity, age estimation is obtained for most of 85 identified companions. Color-absolute magnitude diagrams are constructed to test whether CPM companions are physically related to the primary nearby stars and have the same age. Our carefully selected sample includes three remote white dwarf companions to main-sequence stars and two systems (55 Cnc and GJ 777A) of multiple planets and distant stellar companions. Ten new CPM companions, including three of extreme separations, are found. Multiple hierarchical systems are abundant; more than 25% of CPM components are spectroscopic or astrometric binaries or multiples themselves. Two new astrometric binaries are discovered among nearby CPM companions, GJ 264 and HIP 59000, and preliminary orbital solutions are presented. The Hyades kinematic group (or stream) is presented broadly in the sample, but we find few possible thick-disk objects and no halo stars. It follows from our investigation that moderately young (age<~1 Gyr) thin-disk dwarfs are the dominating species in the near CPM systems, in general agreement with the premises of the dynamical survival paradigm.

Makarov, V. V.; Zacharias, N.; Hennessy, G. S.

2008-11-01

316

STEP-compliant NC research: the search for intelligent CAD\\/CAPP\\/CAM\\/CNC integration  

Microsoft Academic Search

Since the first generation of Numerically Controlled (NC) machine tools was developed in the 1950s, there have been many developments which make today's NC machines completely unrecognizable from their early ancestors. Further developments, however, are now being significantly limited by the current programming language (ISO6983 or RS274D) that has been supporting NC manufacture since day one. Today a new standard,

X. W. Xu; H. Wang; J. Mao; S. T. Newman; T. R. Kramer; F. M. Proctor; J. L. Michaloski

2005-01-01

317

Discovery of three new RS Canum Venaticorum-like counterparts to HEAO I X-ray sources  

SciTech Connect

The identification of three high-latitude HEAO I Scanning Modulation Collimator X-ray sources with the chromospherically active RS CVn-like stars HD 113816, HD 146413, and HD 39576 is reported. Optical observations, including coude spectroscopy and broad-band and narrow band photoelectric photometry are presented. The Ca II emission strength of all three stars shows that they are chromospherically active. HD 146413 and HD 39576 exhibit variable X-ray emission in the 1-13 keV energy range, while HD 113816 is a softer and steadier source. The level of X-ray flux detected from these three stars is some one to two orders of magnitude higher than predicted empirically from the Ca II emission fluxes. It is proposed that this emission results from flarelike activity. 106 references.

Buckley, D.A.H.; Tuohy, I.R.; Remillard, R.A.; Bradt, H.V.; Schwartz, D.A.

1987-04-01

318

The substitution reaction of (CNC)Fe-2N? with CO.  

PubMed

The substitution mechanism of two N? ligands in (CNC)Fe-2N? replaced by CO was studied theoretically at the B3LYP/LACVP* level. Both SN1 and SN? mechanisms were considered. The calculated results for the gas phase suggested that: 1) in SN1 mechanism, N? elimination, which involves S?-T? PESs crossing, is the rate control step for both substitution stages. The barrier heights are 9.7 kcal mol(-1) and 13.05 kcal mol(-1), respectively. 2) In SN2 mechanism, the calculated barrier heights on LS PES are respectively 13.7 and 19.83 kcal mol(-1) for the two substitution steps, but S?-T? PESs crossing lowers the two barriers to 10.7 and 15.7 kcal mol(-1), respectively. 3) Inclusion of solvation effect of THF by PCM model, the relative energies of all the key species (including minima, transition states and S?-T? crossing points) do not have great difference from their gas phase relative energies. Considering that for each substitution step, SN1 barrier heights is slightly smaller than SN2 barrier, SN1 mechanism seems to be slightly preferable to SN2 mechanism. PMID:23504069

Liu, Hongyan; Liu, Shuangshuang; Zhang, Xiang

2013-03-17

319

Chameleon stars  

SciTech Connect

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

Dzhunushaliev, Vladimir [Institute for Basic Research, Eurasian National University, Astana, 010008 (Kazakhstan); Institute of Physicotechnical Problems and Material Science of the NAS of the Kyrgyz Republic, 265 a, Chui Street, Bishkek, 720071 (Kyrgyzstan); Folomeev, Vladimir [Institute of Physicotechnical Problems and Material Science of the NAS of the Kyrgyz Republic, 265 a, Chui Street, Bishkek, 720071 (Kyrgyzstan); Singleton, Douglas [Institute for Basic Research, Eurasian National University, Astana, 010008 (Kazakhstan); Physics Department, CSU Fresno, Fresno, California 93740-8031 (United States)

2011-10-15

320

40 CFR 180.545 - Prallethrin (RS)-2-methyl-4-oxo-3-(2-propynyl)cyclopent-2-enyl (1RS)-cis, trans-chrysanthemate...  

Code of Federal Regulations, 2010 CFR

...2-propynyl)cyclopent-2-enyl (1RS)-cis, trans-chrysanthemate; tolerances for...2-propynyl)cyclopent-2-enyl (1RS )-cis, trans -chrysanthemate; tolerances...2-propynyl)cyclopent-2-enyl (1RS )-cis, trans -chrysanthemate as...

2009-07-01

321

40 CFR 180.545 - Prallethrin (RS)-2-methyl-4-oxo-3-(2-propynyl)cyclopent-2-enyl (1RS)-cis, trans-chrysanthemate...  

Code of Federal Regulations, 2010 CFR

...2-propynyl)cyclopent-2-enyl (1RS)-cis, trans-chrysanthemate; tolerances for...2-propynyl)cyclopent-2-enyl (1RS )-cis, trans -chrysanthemate; tolerances...2-propynyl)cyclopent-2-enyl (1RS )-cis, trans -chrysanthemate as...

2010-07-01

322

Four New Variable Stars in Ophiuchus  

NASA Astrophysics Data System (ADS)

Four new variable stars were discovered by serendipity in the Ophiuchus constellation during photometric analysis of the NEO Asteroid (1988 PA), pictures taken in July 2010 from A81 Balzaretto Observatory in Rome. Based on their light curves and colour indexes, the stars were classified in their variable class and registered in the Variable Star Index (VSX) hosted in the AAVSO web site, respectively as one eclipsing variable EA-type or short period eclipsing subgroup of RS CVn-type (UCAC3 196-166827), identified as the optical counterpart of 1RXS J180755.7+074717 X-ray source, two eclipsing binaries EW-type (UCAC3 196-166958 and UCAC3 196-167279) and one very likely as pulsating variable High Amplitude δ,, Scuti type (HADS) or SX Phe (UCAC3 196-167073).

Franco, Lorenzo; Marchini, Alessandro; Papini, Riccardo

2011-03-01

323

Variable Stars  

NASA Astrophysics Data System (ADS)

It is a tradition to observe variable stars using small telescopes; actually, variable stars are the favorites of small telescopes. What it is needed is those telescopes to be well-equipped (to get good observations), and to be supplied with users (to be productive). The first can be easily achieved; the second, related to the poor job prospects, seems more difficult. Keeping in mind that there is no any Observatory, that could cover the whole sky and that an astronomical event can not be repeated, each individual observation, is very valuable. Especially that of variable stars, where the variability of their luminosity can be caused by many reasons, intrinsic or extrinsic. What is missing -from at least some of the small telescopes spread in whole Europe- is better organization. This means that, besides either some research projects of personal interest, or(/and) students training, some others -being parts of international programs- could also be carried out, focusing to specific objects and goals. The work carried out in the field of variable stars with the use of small telescopes in some European countries, will be presented.

Rovithis-Livaniou, Helen

324

Brittle Star  

USGS Multimedia Gallery

A tiny brittle star (the central disc is smaller than a dime) clings to the branches of a soft coral in a sample bucket brought into the shipboard laboratory from a submersible dive. This creature makes its home on the deep, dark ocean floor. ...

2010-04-15

325

Star quality.  

PubMed

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

Dent, Emma

2007-09-20

326

CFH (rs1410996), HTRA1 (rs112000638) and ARMS2 (rs10490923) Gene Polymorphisms are Associated with AMD Risk in Spanish Patients.  

PubMed

ABSTRACT Purpose: Age-related macular degeneration (AMD) is the main cause of legal blindness in the western adult population. We investigated the association between SNPs located in CFH, ARMS2 and HTRA1 and AMD in Spanish patients. Patients and Methods: We obtained peripheral blood samples from 121 patients with a diagnosis of AMD (84 exudative and 37 atrophic) at the Department of Ophthalmology of the University Hospital of Salamanca. We took 91 subjects as a control group. We studied a single nucleotide polymorphism (SNP) in each patient for each of the genes associated with high susceptibility to developing AMD using Real-time PCR with TaqMan probes for CFH and ARMS2 polymorphisms and PCR-RFLP for HTRA1 polymorphism. Results: We observed a statistically significant difference between patients and controls in the distribution of CFH rs1410996 genotypes, patients homozygous for the C-allele have twice the risk of developing the disease (p?=?0.010; OR?=?2,176 (1.194-3.964)). The analysis of ARMS2 rs10490923 polymorphism also showed differences in allelic distribution between the case and control groups (p?rs112000638 polymorphism with an increased representation of the G-allele in the patient's group (p?rs10490923/rs112000638) haplotype increases the risk of developing AMD by 9 times. Conclusions: Our results show that genotypes of ARMS2 (rs10490923), HTRA1 (rs112000638) and CFH (rs1410996) polymorphisms are related to an increased risk of suffering AMD in Spanish patients. PMID:23534868

Cruz-González, Fernando; Cieza-Borrella, Clara; López Valverde, Gloria; Lorenzo-Pérez, Rebeca; Hernández-Galilea, Emiliano; González-Sarmiento, Rogelio

2013-03-27

327

Einstein Observatory coronal temperatures of late-type stars  

SciTech Connect

The results are presented of a survey of the coronal temperatures of late-type stars using the Einstein Observatory IPC. The spectral analysis shows that the frequently found one- and two-temperature descriptions are mainly influenced by the SNR of the data and that models using continuous emission measure distributions can provide equally adequate and physically more meaningful and more plausible descriptions. Intrinsic differences in differential emission measure distributions are found for four groups of stars. M dwarfs generally show evidence for high-temperature gas in conjunction with lower-temperature material, while main-sequence stars of types F and G have the high-temperature component either absent or very weak. Very hot coronae without the lower-temperature component appearing in dwarf stars are evident in most of the giant stars studied. RS CVn systems show evidence for extremely hot coronae, sometimes with no accompanying lower-temperature material. 51 refs.

Schmitt, J.H.M.M.; Collura, A.; Sciortino, S.; Vaiana, G.S.; Harnden, F.R. Jr. (Max-Planck-Institut fuer Physik und Astrophysik, Garching (Germany, F.R.) CNR, Istituto per le Applicazioni Interdisciplinari della Fisica, Palermo (Italy) Palermo, Osservatorio Astronomico (Italy) Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (USA))

1990-12-01

328

Radio emission from RS CVn binary systems  

SciTech Connect

The RS CVn binary stellar systems UX Ari, HR 1099, AR Lac, HR 5110, II Peg, lambda And, and SZ Psc were investigated by use of radio interferometry during the period from July 1982 through August 1983. Interferometry took two forms: Very Large Array (VLA) observations and Very Long Baseline Interferometry (VLBI). The VLA observations determined the characteristic polarization and flux behavior of the centimeter wavelength radio emission. The observed spectral index was near zero during quiescent periods, rising to between 0.5 and 1.0 during active periods. No net linear polarization is observed to a limit of 1.7%. This is expected since the Faraday depth of thermal electrons deduced from x-ray observations is approx. 10/sup 5/. Circular polarization is observed to be less than 20% at all frequencies often with a helicity reversal between 1.6 GHz and 5 GHz. The VLBI observations have shown that the brightness temperatures are often T/sub B/ approx.> 10/sup 10/ /sup 0/K and size sources smaller than or comparable to the overall size of the binary system. These data are consistent with incoherent gyrosynchrotron emission from mildly relativistic electrons which are optically thick to their own radiation at 1.6 GHz and optically thin at 5 GHz and above. The spectral behavior suggests that the radio emission is due to a power-law distribution of electrons.

Doiron, D.J.

1984-01-01

329

New Hydrodynamic Studies of the Explosion of RS Oph  

Microsoft Academic Search

We have continued our studies of the evolution of Thermonuclear Runaways (TNR) in the accreted envelopes of massive white dwarfs (WD) and here we focus on the 2006 outburst of the Recurrent Symbiotic Nova (RN) RS Oph. RS Oph is a member of a small class of close binary systems in which the orbital period is long ( 460 d),

Sumner Starrfield; T. Sunayama; M. Smith; C. Iliadis; W. R. Hix; F. X. Timmes; W. M. Sparks

2009-01-01

330

Configuration control plan for the ports NCS IBM RS/6000  

SciTech Connect

This document describes the actions and responsibilities for maintaining the quality and integrity of the NS software resident on the IBM RS/6000 workstation managed by the Nuclear Criticality Safety group at the Portsmouth Gaseous Diffusion Plant. This document does not address the validation of NS software packages for the RS/6000.

Brown, A.S.

1996-07-01

331

Responding to the 5Rs: An Alternate Perspective of Slowmation  

ERIC Educational Resources Information Center

|This paper is a response to Hoban and Neilsen's (2010) Five Rs model for understanding how learners engage with slowmation. An alternative model (the Learning MMAEPER Model) that builds on the 5Rs model is explained in terms of its use in secondary science preservice teacher education. To probe into the surface and deep learning that can occur…

Kidman, Gillian; Keast, Stephen; Cooper, Rebecca

2012-01-01

332

Near infrared photometry of some RS CVn systems and candidates  

Microsoft Academic Search

Infrared observations in the J, H, and K bands were made on eleven RS CVn systems. Infrared (IR) excess ?0.3 mag in the J, H, and K bands was observed from the three systems UX Ari, HR 1099 and s CrB. Similar observations were also made on the RS CVn candidates HD 26354, 39937, 42449, 51268, and 86005.

R. P. Verma; S. K. Ghosh; K. V. K. Iyengar; T. N. Rengarajan; S. N. Tandon; R. R. Daniel; N. B. Sanwal

1983-01-01

333

Responding to the 5Rs: An Alternate Perspective of Slowmation  

ERIC Educational Resources Information Center

This paper is a response to Hoban and Neilsen's (2010) Five Rs model for understanding how learners engage with slowmation. An alternative model (the Learning MMAEPER Model) that builds on the 5Rs model is explained in terms of its use in secondary science preservice teacher education. To probe into the surface and deep learning that can occur…

Kidman, Gillian; Keast, Stephen; Cooper, Rebecca

2012-01-01

334

Stars : the end of a star  

NSDL National Science Digital Library

What happens during the death of a star? This activity page, part of an interactive laboratory series for grades 8-12, introduces students to the final processes of stars. Here students read about low-mass, medium-mass, and massive stars. Low-mass stars produce white dwarfs. A pop-up window describes how white dwarfs form. Medium-mass stars produce neutron stars and supernova. Pop-up information explains the supernova process. Massive stars undergo carbon burning. An interactive lab activity presents students the opportunity to predict temperature, pressure, and gravity changes that occur during carbon fusion. In a final lab activity, students compare initial star size with the type of death that occurs. Activity questions about star death are provided for each star size and are recordable and printable. Copyright 2005 Eisenhower National Clearinghouse

University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

2003-01-01

335

RADIAL VELOCITY PLANETS DE-ALIASED: A NEW, SHORT PERIOD FOR SUPER-EARTH 55 Cnc e  

SciTech Connect

Radial velocity measurements of stellar reflex motion have revealed many extrasolar planets, but gaps in the observations produce aliases, spurious frequencies that are frequently confused with the planets' orbital frequencies. In the case of Gl 581 d, the distinction between an alias and the true frequency was the distinction between a frozen, dead planet and a planet possibly hospitable to life. To improve the characterization of planetary systems, we describe how aliases originate and present a new approach for distinguishing between orbital frequencies and their aliases. Our approach harnesses features in the spectral window function to compare the amplitude and phase of predicted aliases with peaks present in the data. We apply it to confirm prior alias distinctions for the planets GJ 876 d and HD 75898 b. We find that the true periods of Gl 581 d and HD 73526 b/c remain ambiguous. We revise the periods of HD 156668 b and 55 Cnc e, which were afflicted by daily aliases. For HD 156668 b, the correct period is 1.2699 days and the minimum mass is (3.1 {+-} 0.4) M{sub +}. For 55 Cnc e, the correct period is 0.7365 days-the shortest of any known planet-and the minimum mass is (8.3 {+-} 0.3) M{sub +}. This revision produces a significantly improved five-planet Keplerian fit for 55 Cnc, and a self-consistent dynamical fit describes the data just as well. As radial velocity techniques push to ever-smaller planets, often found in systems of multiple planets, distinguishing true periods from aliases will become increasingly important.

Dawson, Rebekah I.; Fabrycky, Daniel C., E-mail: rdawson@cfa.harvard.ed, E-mail: daniel.fabrycky@gmail.co [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., MS-10, Cambridge, MA 02138 (United States)

2010-10-10

336

A holistic approach to carbon-enhanced metal-poor stars  

NASA Astrophysics Data System (ADS)

Context. Carbon-enhanced metal-poor (CEMP) stars are known to have properties that reflect the nucleosynthesis of the first low- and intermediate-mass stars, because most have been polluted by a now-extinct AGB star. Aims: By considering abundances in the various CEMP subclasses separately, we try to derive parameters (such as metallicity, mass, temperature, and neutron source) characterising AGB nucleosynthesis from the specific signatures imprinted on the abundances, and separate them from the impact of thermohaline mixing, first dredge-up, and dilution associated with the mass transfer from the companion. Methods: To place CEMP stars in a broader context, we collect abundances for about 180 stars of various metallicities (from solar to [Fe/H] =-4), luminosity classes (dwarfs and giants), and abundance patterns (e.g. C-rich and poor, Ba-rich and poor), from both our own sample and the literature. Results: We first show that there are CEMP stars that share the properties of CEMP-s stars and CEMP-no stars (which we refer to as CEMP-low-s stars). We also show that there is a strong correlation between Ba and C abundances in the s-only CEMP stars. This represents a strong detection of the operation of the 13C neutron source in low-mass AGB stars. For the CEMP-rs stars (seemingly enriched with elements from both the s- and r-processes), the correlation of the N abundances with abundances of heavy elements from the 2nd and 3rd s-process peaks bears instead the signature of the 22Ne neutron source. Since CEMP-rs stars also exhibit O and Mg enhancements, we conclude that extremely hot conditions prevailed during the thermal pulses of the contaminating AGB stars. We also note that abundances are not affected by the evolution of the CEMP-rs star itself (especially by the first dredge-up). This implies that mixing must have occurred while the star was on the main sequence, and that a large amount of matter must have been accreted so as to trigger thermohaline mixing. Finally, we argue that most CEMP-no stars (with neutron-capture element abundances comparable to non-CEMP stars) are likely the extremely metal-poor counterparts of CEMP neutron-capture-rich stars. We also show that the C enhancement in CEMP-no stars declines with metallicity at extremely low metallicity ([Fe/H] < -3.2). This trend is not predicted by any of the current AGB models. Tables 1-4 are only available in electronic form at http://www.aanda.org

Masseron, T.; Johnson, J. A.; Plez, B.; van Eck, S.; Primas, F.; Goriely, S.; Jorissen, A.

2010-01-01

337

Death Star  

NSDL National Science Digital Library

Death Star, a program from the PBS NOVA series, probes the deep mysteries of gamma-ray bursts, the most powerful celestial explosions since the Big Bang. A description of what would happen to Earth if a gamma-ray burst occurred in our own galaxy, a celestial glossary, and a virtual tour of the electromagnetic spectrum are included. Additional websites and published works about space topics are given, and the accompanying video is available to order.

338

Symbiotic Stars  

NASA Astrophysics Data System (ADS)

Symbiotic stars are interacting binary systems composed of a white dwarf (WD) accreting at high rate from a cool giant companion, which frequently fills its Roche lobe. The WD usually is extremely hot and luminous, and able to ionize a sizeable fraction of the cool giant wind, because it is believed the WD undergoes stable hydrogen nuclear burning on its surface of the material accreted from the companion. This leads to consider symbiotic stars as good candidates for the yet-to-be-identified progenitors of type Ia supernovae. Symbiotic stars display the simultaneous presence of many different types of variability, induced by the cool giant, the accreting WD, the circumstellar dust and ionized gas, with time scales ranging from seconds to decades. The long orbital periods (typically a couple of years) and complex outburst patterns, lasting from a few years to a century, make observations from professionals almost impossible to carry out, and open great opportunities to amateur astronomers to contribute fundamental data to science.

Munari, U.

2012-06-01

339

Exceptional Stars  

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

340

Catalogue of Main Characteristics of Individual Pulsational Cycles of 35 Mira-Type Stars  

NASA Astrophysics Data System (ADS)

The characteristics of individual cycles of 35 Mira-type stars are tabulated: the moments and brightness of the extrema, the inverse slopes dt/dm of the light curves and corresponding error estimates. The observations for the analysis are taken from the AFOEV and VSOLJ databases for the stars: R And, W And, R Aql, R Aur, X Aur, R Boo, T Cam, U Cmi, R Cas, S Cas, T Cas, V Cas, W Cas, S Cep, T Cep, V Cnc, V Crb, ? Cyg, RT Cyg, W Dra, T Gem, U Her, R Hya, R Leo, R LMi, R Lep, R Lyn, W Lyr, X Oph, W Peg, Y Per, R UMa, S UMa, S UMi, T UMi.

Marsakova, V. I.; Andronov, I. L.

341

RS-Predictor models augmented with SMARTCyp reactivities: Robust metabolic regioselectivity predictions for nine CYP isozymes  

PubMed Central

RS-Predictor is a tool for creating pathway-independent, isozyme-specific site of metabolism (SOM) prediction models using any set of known cytochrome P450 substrates and metabolites. Until now, the RS-Predictor method was only trained and validated on CYP 3A4 data, but in the present study we report on the versatility the RS-Predictor modeling paradigm by creating and testing regioselectivity models for substrates of the nine most important CYP isozymes. Through curation of source literature, we have assembled 680 substrates distributed among CYPs 1A2, 2A6, 2B6, 2C19, 2C8, 2C9, 2D6, 2E1 and 3A4, which we believe is the largest publicly accessible collection of P450 ligands and metabolites ever released. A comprehensive investigation into the importance of different descriptor classes for predicting the regioselectivity of each isozyme is made through the generation of multiple independent RS-Predictor models for each set of isozyme substrates. Two of these models include a DFT reactivity descriptor derived from SMARTCyp. Optimal combinations of RS-Predictor and SMARTCyp are shown to have stronger performance than either method alone, while also exceeding the accuracy of the commercial regioselectivity prediction methods distributed by StarDrop and Schrödinger, correctly identifying a large proportion of the metabolites in each substrate set within the top two rank-positions: 1A2(83.0%), 2A6(85.7%), 2B6(82.1%), 2C19(86.2%), 2C8(83.8%), 2C9(84.5%), 2D6(85.9%), 2E1(82.8%), 3A4(82.3%) and merged(86.0%). Comprehensive datamining of each substrate set and careful statistical analyses of the predictions made by the different models revealed new insights into molecular features that control metabolic regioselectivity and enable accurate prospective prediction of likely SOMs.

Zaretzki, Jed; Rydberg, Patrik; Bergeron, Charles; Bennett, Kristin P.; Olsen, Lars

2012-01-01

342

The AP stars  

Microsoft Academic Search

Ap stars are stars with peculiar characteristics which made it difficult to assign them to the stellar types of the conventional classification scheme. Ap stars are frequently observed. Up to 10% Ap stars are found in the case of the concerned spectral types. Attention is given to the spectroscopic properties of the Ap stars, aspects of stellar spectrum and stellar

H. Muthsam

1977-01-01

343

Star formation in disks  

Microsoft Academic Search

It is noted that the principal characteristics of the stellar populations in galaxies depend on the history of star formation and the initial mass spectrum with which the stars are formed. Whereas there have been a number of attempts to model the history of star formation in galaxies using various quasi-theoretical descriptions of star formation, star formation remains poorly understood

R. B. Larson

1983-01-01

344

Synthesis of an isomeric mixture (24RS,25RS) of sodium scymnol sulfate.  

PubMed

This is the first reported multistep synthesis of the shark bile sterol sodium scymnol sulfate epimeric at the C-24 hydroxyl and C-27 sulfate positions. The starting cholic acid was protected as the tetrahydropyran ether (THP) derivative, reduced to the C-24 alcohol and oxidized to the protected aldehyde. This aldehyde was then coupled with methyl 3-hydroxypropionate using 2equiv. of lithium diethylamide at -65 degrees C to produce methyl (24RS,25RS)-24,27-dihydroxy-3alpha,7alpha,12alpha,tris[(tetrahydropyran-2-yl)oxy]-5beta-cholestan-26-oate. After protecting the 24 and 27 hydroxyls as the THP derivatives, this fully protected ester was then reduced to the monoalcohol. The monoalcohol was sulfated using the sulfur trioxide-triethylamine complex in dimethylformamide. The protective THP groups were removed with methanolic HCl and the sulfate was converted to the sodium salt with sodium ethoxide in methanol. This general synthetic scheme has application to produce a range of monosulfated sterols. PMID:18255112

Harney, Donald W; Macrides, Theodore A

2007-12-15

345

The optical counterpart of the X-ray source H0253+193 - a distant, high-luminosity RS Canum Venaticorum system  

SciTech Connect

Optical and near-infrared photometry in the VRIJHK and CO (2.35 microns) bands and optical spectroscopy and polarimetry reveal that the optical counterpart of the X-ray source H0253+193 is most likely a RS CVn binary system. The results show a visual extinction of 11.3 mag to the star, with an IR excess possibly due a cooler binary companion or circumstellar material. It is suggested that the I-band polarization of 8.1 + or - 1.8 may be induced in the starlight by passage through the molecular cloud. The lack of strong H-alpha emission in the optical spectrum argues against the possibility of a classical T Tauri star, and the IR excess argues against a naked T Tauri star. The wide energy spectrum found in the dereddened optical and near-infrared photometry supports the binary star model. 40 refs.

Clemens, D.P.; Leah, R.W. (Boston Univ., MA (USA) San Diego State Univ., CA (USA))

1989-10-01

346

Theoretical and experimental research on machine tool servo system for ultra-precision position compensation on CNC lathe  

NASA Astrophysics Data System (ADS)

The theories and techniques for improving machining accuracy via position control of diamond tool's tip and raising resolution of cutting depth on precise CNC lathes have been extremely focused on. A new piezo-driven ultra-precision machine tool servo system is designed and tested to improve manufacturing accuracy of workpiece. The mathematical model of machine tool servo system is established and the finite element analysis is carried out on parallel plate flexure hinges. The output position of diamond tool's tip driven by the machine tool servo system is tested via a contact capacitive displacement sensor. Proportional, integral, derivative (PID) feedback is also implemented to accommodate and compensate dynamical change owing cutting forces as well as the inherent non-linearity factors of the piezoelectric stack during cutting process. By closed loop feedback controlling strategy, the tracking error is limited to 0.8 ?m. Experimental results have shown the proposed machine tool servo system could provide a tool positioning resolution of 12 nm, which is much accurate than the inherent CNC resolution magnitude. The stepped shaft of aluminum specimen with a step increment of cutting depth of 1 ?m is tested, and the obtained contour illustrates the displacement command output from controller is accurately and real-time reflected on the machined part.

Ma, Zhichao; Hu, Leilei; Zhao, Hongwei; Wu, Boda; Peng, Zhenxing; Zhou, Xiaoqin; Zhang, Hongguo; Zhu, Shuai; Xing, Lifeng; Hu, Huang

2010-08-01

347

Inhibition of mini-TyrRS-induced angiogenesis response in endothelial cells by VE-cadherin-dependent mini-TrpRS.  

PubMed

To clarify whether a VE-cadherin-dependent pathway allows mini-TrpRS to inhibit mini-TrpRS-induced new blood vessel formation in endothelial cells (ECs), the inhibitory effects of mutant mini-TrpRS and VE-cadherin on mini-TrpRS-induced angiogenesis were investigated. The effects of mini-TyrRS and mini-TrpRS on EC proliferation were evaluated using an MTT colorimetric assay. Cell migration was assayed using a modified Boyden chamber technique. The angiogenic activity in vitro was evaluated by transwell migration assay and matrigel-induced capillary tube formation. It was found that mini-TrpRS does not inhibit the mini-TyrRS-induced proliferation and migration of EC under the condition of VE-cadherin knockout. While wild-type mini-TrpRS inhibited mini-TyrRS-induced angiogenesis, this activity vanished for the mutant protein. Also, the promotion of angiogenesis by mini-TyrRS and the inhibition of angiogenesis by mini-TrpRS were VEGFR2 dependent but not VEGF dependent. Mini-TyrRS was able to increase the protein expression of VEGFR-2 in the presence of VE-cadherin, while no stimulatory effect of mini-TyrRS was detected when VE-cadherin was not present. Angiogenesis is therefore stimulated by mini-TyrRS and inhibited by mini-TrpRS, raising the possibility that mini-TyrRS and mini-TrpRS stimulate a common downstream signaling event: VE-cadherin. Thus, naturally occurring fragments of the two proteins involved in translation, TyrRS and TrpRS, have opposing activities on angiogenesis. The opposing activities of the two tRNA synthetases suggest tight regulation of the balance between pro- and antiangiogenic stimuli. PMID:21442253

Zeng, Rui; Chen, Yu-cheng; Zeng, Zhi; Liu, Xiao-xia; Liu, Rui; Qiang, Ou; Li, Xian

2011-03-26

348

Investigation of RS spectra of crystalline potassium perchlorate  

Microsoft Academic Search

The processes of molecular relaxation in crystalline potassium perchlorate are investigated by the method of RS spectroscopy\\u000a in the field of totally symmetrical oscillation v1(A) of the amen ClO\\u000a 4\\u000a ?\\u000a . The parameters of reorientation in relation to the polarized RS lines are evaluated from the temperature dependences of\\u000a line widths. It is established that in KClO4 the reorientation

A. R. Aliev; A. I. Akaeva; A. Z. Gadzhiev

1998-01-01

349

Near infrared photometry of some RS CVn systems and candidates  

Microsoft Academic Search

Infrared observations in the J, H, and K bands were made on eleven RS CVn systems. Infrared (IR) excess ⪆0.3 mag in the J, H, and K bands was observed from the three systems UX Ari, HR 1099 and sigma CrB. Similar observations were also made on the RS CVn candidates HD 26354, 39937, 42449, 51268, and 86005. The IR

R. P. Verma; S. K. Ghosh; K. V. K. Iyengar; S. N. Tandon; R. R. Daniel; N. B. Sanwal; T. N. Rengarajan

1983-01-01

350

Design and Implementation of MaRS: A Routing Testbed  

Microsoft Academic Search

This paper presents the design and implementation of MaRS, a discrete-event simulation testbedfor developing routing algorithms for wide-area computer networks. MaRS allows the user to definea network configuration consisting of physical network, routing algorithm and workload. The usercan control its simulation, log the values of selected parameters, and save, load and modify networkconfigurations. To accomodate a variety of network configurations

Cengiz Alaettinoglu

1992-01-01

351

Cool stars, stellar systems, and the sun; Proceedings of the 6th Cambridge Workshop, Seattle, WA, Sept. 18-21, 1989  

SciTech Connect

The present conference on cool stars, stellar systems, and the sun encompasses stellar chromospheres and coronae, binary stars, the stellar evolution of contracting stars and red giants, stellar evolution abundances of the elements, mass loss and envelopes, and stellar pulsation. Specific issues addressed include theories regarding the acoustic and magnetic heating of stellar chromospheres and coronae, stellar granulation, wave heating in magnetic flux tubes, observations of the solar Ca-II lines, longitudinal-transverse magnetic tube waves in the solar atmosphere, radio emission from rapidly rotating cool giant stars, and spot temperatures and area coverages on active dwarf stars. Also addressed are the optical and UV spectra of RS-CVn stars, emission lines from T-Tauri stars, the spectroscopy of HR1614 group stars, red giants in external galaxies, the rotation of evolved stars, the transition from red giant to planetary nebula, and radiative transfer in the dynamic atmospheres of variable stars.

Wallerstein, G.; (Washington, University, Seattle)

1990-01-01

352

An open CAM system for dentistry on the basis of China-made 5-axis simultaneous contouring CNC machine tool and industrial CAM software.  

PubMed

China-made 5-axis simultaneous contouring CNC machine tool and domestically developed industrial computer-aided manufacture (CAM) technology were used for full crown fabrication and measurement of crown accuracy, with an attempt to establish an open CAM system for dental processing and to promote the introduction of domestic dental computer-aided design (CAD)/CAM system. Commercially available scanning equipment was used to make a basic digital tooth model after preparation of crown, and CAD software that comes with the scanning device was employed to design the crown by using domestic industrial CAM software to process the crown data in order to generate a solid model for machining purpose, and then China-made 5-axis simultaneous contouring CNC machine tool was used to complete machining of the whole crown and the internal accuracy of the crown internal was measured by using 3D-MicroCT. The results showed that China-made 5-axis simultaneous contouring CNC machine tool in combination with domestic industrial CAM technology can be used for crown making and the crown was well positioned in die. The internal accuracy was successfully measured by using 3D-MicroCT. It is concluded that an open CAM system for dentistry on the basis of China-made 5-axis simultaneous contouring CNC machine tool and domestic industrial CAM software has been established, and development of the system will promote the introduction of domestically-produced dental CAD/CAM system. PMID:22038364

Lu, Li; Liu, Shusheng; Shi, Shenggen; Yang, Jianzhong

2011-10-25

353

The CNC development of the sawing and milling machining center for plastic door and window PVC profile based on Fanuc0  

Microsoft Academic Search

By developing secondly FANUC - OMD system, the control system accorded with requirements of the sawing and milling machining center for plastic door and window PVC (polyvinyl chloride) profile is accomplished. Based on researching the structure, the function, the process of the technologies and the control requirements of the machining center, had implemented the CNC (computer numerical control)system of the

Hui Zhang; Changsheng Ai; Fang Zhao; Xiangbo Ze

2008-01-01

354

Important miRs of Pathways in Different Tumor Types  

PubMed Central

We computationally determined miRs that are significantly connected to molecular pathways by utilizing gene expression profiles in different cancer types such as glioblastomas, ovarian and breast cancers. Specifically, we assumed that the knowledge of physical interactions between miRs and genes indicated subsets of important miRs (IM) that significantly contributed to the regression of pathway-specific enrichment scores. Despite the different nature of the considered cancer types, we found strongly overlapping sets of IMs. Furthermore, IMs that were important for many pathways were enriched with literature-curated cancer and differentially expressed miRs. Such sets of IMs also coincided well with clusters of miRs that were experimentally indicated in numerous other cancer types. In particular, we focused on an overlapping set of 99 overall important miRs (OIM) that were found in glioblastomas, ovarian and breast cancers simultaneously. Notably, we observed that interactions between OIMs and leading edge genes of differentially expressed pathways were characterized by considerable changes in their expression correlations. Such gains/losses of miR and gene expression correlation indicated miR/gene pairs that may play a causal role in the underlying cancers.

Wuchty, Stefan; Arjona, Dolores; Bauer, Peter O.

2013-01-01

355

Sea-launched TacSats for Responsive Space (STaRS)  

Microsoft Academic Search

The Responsive Space community has focused on Responsive Launch as an area of improvement that would help space become more responsive. Unfortunately, developing a Responsive Launch capability is fraught with difficulties. American launch facilities (i.e., Eastern Range, Western Range, Kwajalein, etc.) have numerous logistical and physical limitations that restrict U.S ability to quickly launch a satellite, including: restricted launch fans,

Robert Carneal

356

Prognostic significance of interleukin-6 single nucleotide polymorphism genotypes in neuroblastoma: rs1800795 (promoter) and rs8192284 (receptor)  

PubMed Central

Purpose Neuroblastoma is a childhood cancer of the sympathetic nervous system and many patients present with high risk disease. Risk stratification, based on pathology and tumor-derived biomarkers, has improved prediction of clinical outcomes, but overall survival rates remain unfavorable and new therapeutic targets are needed. Some studies suggest a link between interleukin-6 and more aggressive behavior in neuroblastoma tumor cells. Therefore, we examined the impact of two IL-6 single nucleotide polymorphisms (SNP) on neuroblastoma disease progression. Experimental design DNA samples from 96 high risk neuroblastoma patients were screened for two SNP that are known to regulate the serum levels of IL-6 and the soluble IL-6 receptor (IL-6R), rs1800795 and rs8192284 respectively. The genotype for each SNP was determined in a blinded fashion and independent statistical analysis was performed to determine SNP-related event free survival (EFS) and overall survival (OS) rates. Results The rs1800795 IL-6 promoter SNP is an independent prognostic factor for EFS and OS in -high risk neuroblastoma patients. In contrast, the rs8192284 IL-6 receptor SNP revealed no prognostic value. Conclusions The rs1800795 SNP (-174 IL-6 (G>C) represents a novel and independent prognostic marker for both EFS and OS in high risk neuroblastoma. Since the rs1800795 SNP (-174 IL-6 (G>C) has been shown to correlate with production of IL-6, this cytokine may represent a target for development of new therapies in neuroblastoma.

Lagmay, Joanne P.; London, Wendy B.; Gross, Thomas G.; Termuhlen, Amanda; Sullivan, Nicholas; Axel, Amy; Mundy, Bethany; Ranalli, Mark; Canner, Jason; McGrady, Patrick; Hall, Brett

2009-01-01

357

Milliarcsecond resolution infrared observations of the recurrent nova RS Ophiuchi and low mass stellar systems  

NASA Astrophysics Data System (ADS)

We introduce the method of long-baseline stellar interferometry starting with the fundamental combination of electric fields. We describe beam combination techniques and how they are realized at the observatories used in the conduct of this research. We subsequently give a mathematical description of the Keck Interferometer Nuller and describe our pathfinder effort to produce the first science with this instrument. We present the results of a 2.5 year observing campaign using four different observatories; the Spitzer Space Telescope , the Infrared and Optical Telescope Array on Mt. Hopkins, Arizona, the Palomar Testbed Interferometer on Mt. Palomar, California, and the Keck Interferometer on Mauna Kea, Hawaii. We describe our observations of a broad array of low-mass binary stars and the recurrent nova RS Ophiuchi in outburst--a candidate Type Ia supernova progenitor. We present calculations that suggest a new paradigm for dust creation in recurrent novae. We explore this paradigm through analysis of line and continuum emission from near peak brightness to quiescence. We report radial velocity and astrometric model fitting on the low-mass M-dwarf binary Gliese 268. We derive masses of the constituent stars with 0.5% uncertainty.

Barry, Richard Keith, Jr.

358

Fixed-Phase Observations of RS Canum Venaticorum and BY Draconis Systems  

NASA Astrophysics Data System (ADS)

We present our data set of same-hemisphere, or fixed-phase, observations of five RS Canum Venaticorum and BY Draconis binaries made with the Solar-Stellar Spectrograph at Lowell Observatory. The purpose of this study is to evaluate the level of intrinsic variability in the components of these systems, and to compare it with variability arising from rotational modulation and from long-term, activity cycle-related variability. We obtain fixed-phase observations by observing tidally locked binaries with near-integral-day periods. The fixed-phase observations reveal that the intrinsic variability of the stellar hemispheres is significantly less than the variability induced by rotational modulation or by long-term, activity-cyclic evolution, but only when several spectral features are considered in tandem. Fixed-phase ``flickering'' of the stellar hemispheres is often apparent at a higher level than the rotational or long-term modulation in individual activity indicators. Interpretation of rotational or long-term modulation in active, late-type stars using data that do not allow quantification of the fixed-phase variability of the stars (i.e., data that do not span several rotational periods) is extremely risky.

Hall, Jeffrey C.; Wolovitz, Jeffrey B.

1998-06-01

359

Lifestyles of the Stars.  

ERIC Educational Resources Information Center

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

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

360

Theories of star formation  

Microsoft Academic Search

A well defined theory of star formation does not yet exist. A serious deficiency therefore remains in current theories of the structure and evolution of stars. Since stars must be forming at the present phase of Galactic evolution, it is pertinent to investigate what conditions favour star formation. Observational evidence for the pre-main sequence phase of stellar evolution is entirely

D. McNally

1971-01-01

361

Extragalactic Star Clusters: the Resolved Star Approach  

NASA Astrophysics Data System (ADS)

The physical processes leading to the dissolution of star clusters is a topic barely studied and still not understood. We started a pilot project to develop a new approach to directly detect and study the properties of stellar clusters while they are being destroyed. Our technique currently under development makes use of the exceptional spatial resolution and sensitivity of the ACS camera onboard HST to resolve individual stars in nearby galaxies. PSF stellar photometry and color-magnitude diagrams allows us to separate the most massive stars (more likely to be in clusters) from the star field background. While applying the method to the normal spiral galaxy NGC1313, we found that the method of studying star clusters through resolved stars in nearby galaxies is even more powerful than we first expected. The stellar maps obtained for NGC1313 show that a large fraction of early B-type stars contained in the galaxy are already part of the star field background rather that being in star clusters. Such stars live for 5 to 25 Myr. Since most stars form in clusters, the presence of such massive stars in the field means that they must have left their birthplace very rapidly. It also means that the processes involved in the dissolution of the clusters are extremely efficient. The only plausible explanation for so many young stars to be in the field background is the infant mortality of star clusters. We will present the latest results on the two galaxies NGC 1313 and IC 2475 and discuss the potential of the new approach for studying extragalactic stellar clusters.

Pellerin, Anne; Meyer, M. J.; Jason, H.; Calzetti, D.

2006-12-01

362

Binarity and multiperiodicity in high-amplitude delta Scuti stars .  

NASA Astrophysics Data System (ADS)

We present our first results for a sample of southern high-amplitude delta Scuti stars (HADS), based on a spectrophotometric survey started in 2003. For CY Aqr and AD CMi, we found very stable light and radial velocity (RV) curves; we confirmed the double-mode nature of ZZ Mic, BQ Ind and RY Lep. Finally, we detected gamma -velocity changes in RS Gru and RY Lep.

Derekas, A.; Kiss, L. L.; Csák, B.; Griffin, J.; Lindström, C.; Mészáros, Sz.; Székely, P.; Ashley, M. C. B.; Bedding, T. R.

363

Coordinated ultraviolet and radio observations of selected nearby stars. Final technical report  

SciTech Connect

All of the US2 shifts assigned were successfully completed with simultaneous International Ultraviolet Explorer (IUE) and the Very Large Array (VLA) observations of the proposed target stars. The target stars included dwarf M flare stars and RS CVn stars. The combined ultraviolet (IUE) and microwave (VLA) observations have provided important new insights to the radiation mechanisms at these two widely-separated regions of the electromagnetic spectrum. The VLA results included the discovery of narrow-band microwave radiation and rapid time variations in the microwave radiation of dwarf M flare stars. The results indicate that conventional radiation mechanisms cannot explain the microwave emission from these stars. In general, ultraviolet variations and bursts occur when no similar variations are detected at microwave wavelengths and vice versa. Although these is some overlap, the variations in these two spectral regions are usually uncorrelated, suggesting that there is little interaction between the activity centers at the two associated atmospheric levels.

Lang, K.R.

1987-09-01

364

Herschel's Star Gages  

NSDL National Science Digital Library

The EJS Herschel's Star Gages Model illustrates William Herschel's methods of "star gages" by which he attempted to map out the shape of our galaxy in 1785. Herschel's star gages (sic) relied on two important assumptions: that Herschel's telescope (his "large 20 foot" with an 18.5 inch aperture) could see to the ends of the galaxy, and that within the galactic system stars are distributed uniformly. If the first assumption holds then the stars seen in the telescope all lie within a conical region of space with the apex at the telescope and the base at the edge of the galaxy. If the second assumption holds then the number of stars seen in the telescope is proportional to the volume of this cone. Since the volume of the cone is proportional to the cube of its height, the distance to the galactic edge in any direction is proportional to the cube root of the number of stars seen in that direction. This simulation allows the user to use Herschel's method of star gages to map out the shape of an artificial "star system" for which Herschel's assumptions are valid. One window shows the view through a telescope, with a slider to change the telescopes direction (around a single fixed axis). Another window shows a 3D view of the star system, showing either all of the stars in the system or only those stars visible through the telescope. A third window shows a plot of the star gages. Plotting star gages for many different directions maps out a cross-section of the star system. An optional slider allows the user to decrease the distance to at which stars are no longer visible, and a menu allows the user to select a star system in which the stars are not distributed uniformly. These options let the user explore how violations of Herschel's two fundamental assumptions invalidate his star gage method.

Timberlake, Todd

2011-05-28

365

Differential Rotation in Two RS CVn Systems: ? Gem and ? And  

NASA Astrophysics Data System (ADS)

The differentially rotating convective envelope is an indispensable element of the magnetic dynamo working in RS CVn-systems. Tidal coupling is responsible for maintaining fast rotation, and also the observed high level of magnetic activity. In this work, we compare the physical properties of two well known RS CVn-type binaries, that is the long-period system ? Gem and the ellipsoidal variable ? And. For the comparison, we use the results obtained from processing time-series Doppler images. We also aim at understanding how differential rotation could be affected by tidal forces in such close binaries.

K?vári, Zsolt; Bartus, János; Kriskovics, Levente; Oláh, Katalin; Vida, Krisztián; Ribárik, Orsolya; Strassmeier, Klaus G.

2012-04-01

366

Does Saturn have rings outside 10 R(s)?  

NASA Astrophysics Data System (ADS)

Vasundhara et al. and Mahra et al. have recently reported detections of new saturnian ring systems near 12.5 and 19.5 Saturn radii (RS), respectively. The authors review the Voyager ion and electron data in the energy range 30 - 1,000 keV as measured by the Low Energy Charged Particle experiment. There is no convincing evidence for ring matter outside 10 RS in these data. Features in the charged particle fluxes in these regions are more readily explained by temporal variations and/or spatial structure unrelated to ring matter, such as the mantle on the dayside and/or detached plasma sheets.

Cheng, A. F.; Lanzerotti, L. J.; Maclennan, C. G.

1985-10-01

367

Star Formation in Galaxies  

NASA Astrophysics Data System (ADS)

The process of star formation is at the core of the evolutionary cycle of galaxies, as newborn stars produce new chemical elements, dust, and light. The energetic output delivered first by stellar winds and then by supernovae a few Myr after a star formation episode may also directly impact on the evolution of galaxies and their interstellar medium (ISM), as well as having an effect on the intergalactic medium (IGM), through feedback and outflows.This chapter concerns star formation on galactic scales. First, the galactic processes that may affect large-scale star formation are presented. Second, the various methods to measure star formation rates are discussed (star formation tracers, timescales, calibrations, limits). Finally, the observational status concerning star formation in galaxies (its relation to other quantities and its evolution) is presented. The Schmidt Law (star formation rate-gas relationship) is amply discussed.

Boissier, Samuel

368

Frequency Distribution of COMT Polymorphisms in Greek Patients with Schizophrenia and Controls: A Study of SNPs rs737865, rs4680, and rs165599  

PubMed Central

Schizophrenia, a severe psychiatric condition, is characterized by disturbances of cognition, emotion, and social functioning. The disease affects almost 1% of world population. Recent studies evaluating the role of catechol-O-methyltransferase enzyme (COMT) polymorphisms in the pathogenesis of schizophrenia have resulted in ambiguous findings. The current study examined the association of schizophrenia with three COMT polymorphisms, namely, rs737865, rs4680, and rs165599 in a Greek population. There was no significant association between schizophrenia and any of the three SNPs examined. However, haplotype analysis showed that cases have higher frequency of the T-A-A haplotype, and participants with that haplotype were at increased risk for developing schizophrenia (OR = 1.52; CL?:?1.12–2.08; P = 0.008). Furthermore, patients with schizophrenia displayed an excess of TC/AA/AA and the TT/AA/GA genotypes. Similarly a protective effect of TT/GG/GG and TT/GA/GG was suggested by our results.

Maria, Kotrotsou; Charalampos, Touloumis; Vassilakopoulou, Dido; Stavroula, Syriou; Vasiliki, Kalampoki; Nikolaos, Drakoulis

2012-01-01

369

Photometric investigation of the RS CVn binary CF Tuc  

Microsoft Academic Search

Photometry of the southern RS CVn binary CF Tuc collected from over a sixteen year period since December 1978, is analysed. 25 data-sets, mainly in broadbandV, have been studied for trends in the effects of surface maculation.

E. Budding; M. Zeilik

1995-01-01

370

Flaring on RS CVn systems: Results from EUVE Photometry  

Microsoft Academic Search

We present broadband EUV photometry for a sample of RS CVn systems observed with the Deep Survey Spectrometer and Right Angle Program (RAP) Scanners on the Extreme Ultraviolet Explorer (EUVE). We have developed robust data analysis and light curve software for the interpretation of these data. Large-scale flaring activity is seen on 15 of the 18 systems studied. These binaries

R. A. Osten; A. Brown; T. R. Ayres

1998-01-01

371

Near Infrared Photometry of Some RS CVn Systems  

Microsoft Academic Search

The authors observed 11 RS CVn systems during 1981 - 82 at the 1.2 m telescope of Osmania University, Hyderabad, in the JHK bands. Many of these systems exhibit infrared excesses. The origin of this excess radiation is briefly discussed.

R. P. Verma; S. K. Ghosh; K. V. K. Iyengar; T. N. Rengarajan; S. N. Tandon; R. R. Daniel; N. B. Sanwal

1984-01-01

372

Role of nAChRs in Lung Cancer  

Center for Drug Evaluation (CDER)

Text Version... GPCRs GABARs Functions of nAChRs in the Brain Page 7. ... Nicotine Addiction Page 8. In analogy to its function in the brain, the ?7nAChR ... More results from www.fda.gov/downloads/drugs/newsevents

373

The circumstellar envelopes of the Cepheids ? Carinae and RS Puppis . Comparative study in the infrared with Spitzer, VLT/VISIR, and VLTI/MIDI  

NASA Astrophysics Data System (ADS)

Context: Compact circumstellar envelopes (CSEs) have been detected around several Cepheids by interferometry. In particular, observations with the VINCI instrument revealed in 2006 a compact envelope around the long period Cepheid ? Car (P = 35.5 days). Another Cepheid, RS Pup (P = 41.4 days), presents a large (?2 arcmin) circumstellar nebula scattering the Cepheid light in the visible. These envelopes are particularly interesting for two reasons: their presence could impact the Cepheid distance scale, and they could imply stellar mass loss. Aims: Our goal is to establish the spatial and spectral properties of the CSEs of ? Car and RS Pup. This is done through a parametrization of the envelopes in terms of fractional flux (with respect to the star) and angular size. Methods: We retrieved archival Spitzer images of the two stars (? = 3.5-70 ?m), and obtained new diffraction-limited imaging with the VLT/VISIR camera in BURST mode (? = 8.6-11.9 ?m), as well as interferometric observations with the VLTI/MIDI beam combiner (? = 8-13 ?m). This combination of single-telescope and interferometric techniques allows us to probe the envelopes of the two Cepheids over a broad range of angular scales, from arcminutes to milliarcseconds. Results: The circumstellar envelope of RS Pup is resolved spatially at 24 and 70 ?m by Spitzer, and around 10 ?m by MIDI and VISIR. The envelope of ? Car appears much more compact, and is resolved only in the VISIR and MIDI observations. The infrared excesses we detect around RS Pup and ? Car are both very significant, but differ considerably in spectral and spatial properties. We detect a warm component in the CSE of both stars at a spatial scale of a few 100 to a few 1000 AU. In addition, RS Pup presents a very large (several 100 000 AU) and cold (?40 K) dusty envelope. Conclusions: The observed properties of the CSEs lead us to propose that the cold dust content of the large reflection nebula surrounding RS Pup has an interstellar origin, while the warm CSEs of the two stars were created by ongoing stellar mass loss. We also speculate that the NGC 7023 reflection nebula surrounding the Herbig Be star HD 200775 is an analogue of RS Pup at an age of 100 000 years. The presence of CSEs around the two brightest long-period Cepheids is an indication that many long-period members of this class, if not all, could be surrounded by warm circumstellar envelopes created by mass loss. However, very large dusty envelopes such as that of RS Pup are probably less common, as according to our scenario, they require the presence of a high dust density in the interstellar medium (ISM) at the time of the formation of the Cepheid progenitor. Based on observations made with ESO telescopes at Paranal Observatory, under ESO programs 073.D-0142(B), 077.D-0500(A), 078.D-0739(B), 078.D-0739(D) and 081.D-0165(A).

Kervella, P.; Mérand, A.; Gallenne, A.

2009-05-01

374

Time-optimal traversal of curved paths by Cartesian CNC machines under both constant and speed-dependent axis acceleration bounds  

Microsoft Academic Search

Algorithms are developed to compute the feedrate variation along a curved path, that ensures minimum traversal time for a 3-axis CNC machine subject to both fixed and speed-dependent axis acceleration bounds arising from the output-torque characteristics of the axis drive motors. For a path specified by a polynomial parametric curve, the time-optimal feedrate is determined as a piecewise-analytic function of

Sebastian D. Timar; Rida T. Farouki

2007-01-01

375

Astronomy: A Star Party  

NSDL National Science Digital Library

This lesson is designed to teach students about the functions of a telescope, the daylight uses of a telescope, the parts of the telescope, and to identify and view certain stars and planets during a star party at night.

376

Quark core stars, quark stars and strange stars  

SciTech Connect

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.

Grassi, F.

1988-01-01

377

Spatially extended emission around the Cepheid RS Puppis in near-infrared hydrogen lines. Adaptive optics imaging with VLT/NACO  

NASA Astrophysics Data System (ADS)

Context. It has been recently discovered that Cepheids harbor circumstellar envelopes (CSEs). RS Pup is the Cepheid that presents the most prominent circumstellar envelope known, the origin of which is not yet understood. Aims: Our purpose is to estimate the flux contribution of the CSE around RS Pup at the one arcsecond scale (~2000 AU) and to investigate its geometry, especially regarding asymmetries, to constrain its physical properties. Methods: We obtained near-infrared images in two narrow band filters centered on ? = 1.644 and 2.180 ?m (NB_1.64 and IB_2.18, respectively) that comprise two recombination lines of hydrogen: the 12-4 and 7-4 (Brackett ?) transitions, respectively. We used NACO's cube mode observations in order to improve the angular resolution with the shift-and-add technique, and to qualitatively study the symmetry of the spatially extended emission from the CSE with a statistical study of the speckle noise. Results: We probably detect at a 2? level an extended emission with a relative flux (compared with the star in the same filter) of 38 ± 17% in the NB_1.64 filter and 24 ± 11% in the IB_2.18 filter. This emission is centered on RS Pup and does not present any detectable asymmetry. We attribute the detected emission to the likely presence of an hydrogen envelope surrounding the star. Based on observations made with ESO telescopes at Paranal observatory under program ID 382.D-0065(A).

Gallenne, A.; Mérand, A.; Kervella, P.; Girard, J. H. V.

2011-03-01

378

Possible selective formation of CNC/sup +/ and CCN/sup +/ in the interstellar reactions of C/sup +/ with HCN and HNC/sup +/  

SciTech Connect

The molecular structures of CNC/sup +/ and CCN/sup +/ have been determined by double zeta self-consistent field (SCF) calculations. Their standard heats of formation are theoretically estimated to be 372 +- 20 and 421 +- 25 kcal mol/sup -1/, respectively, the latter determined by double zeta plus polarization SCF-CI (configuration interaction) calculation of the isomerization energy for CNC/sup +/..-->..CCN/sup +/. Using these results, the available appearance potential data for these ions in the mass spectra of HC/sub 3/N and C/sub 2/N/sub 2/ can be explained by simple reactions, and the numerical agreement between the corresponding experimental and theoretical heats of formation is excellent. With this thermochemical information and mechanistic considerations of C/sup +/ reactions with HCN and HNC, we propose that CNC/sup +/ may be selectively made from HCN, and CCN/sup +/ from HNC, and that this selectivity may play an important role in the chemistry of the interstellar medium. For the polar isomer CCN/sup +/ we report an SCF prediction of its rotational constant (11.93 +- 0.5 GHz) and a higher-level (CI) calculation of its electric dipole moment (2.50 +- 0.2 debye) and nitrogen nuclear quadrupole coupling constant (-4.95 +- 0.5 MHz).

Haese, N.N.; Woods, R.C.

1981-05-15

379

Star formation in irregular galaxies  

Microsoft Academic Search

The problems associated with star formation in irregular galaxies are outlined. The basic model of star formation is reviewed. Global star formation rates, feedback processes, the physical conditions of the interstellar medium which affect star formation, and the internal structures of star-forming regions in irregular galaxies are discussed. In addition, star formation in the amorphous irregular galaxies described by Sandage

D. A. Hunter; J. S. Gallagher III

1989-01-01

380

QCD in Neutron Stars and Strange Stars  

SciTech Connect

This paper provides an overview of the possible role of Quantum Chromo Dynamics (QCD) for neutron stars and strange stars. The fundamental degrees of freedom of QCD are quarks, which may exist as unconfined (color superconducting) particles in the cores of neutron stars. There is also the theoretical possibility that a significantly large number of up, down, and strange quarks may settle down in a new state of matter known as strange quark matter, which, by hypothesis, could be more stable than even the most stable atomic nucleus, {sup 56}Fe. In the latter case new classes of self-bound, color superconducting objects, ranging from strange quark nuggets to strange quark stars, should exist. The properties of such objects will be reviewed along with the possible existence of deconfined quarks in neutron stars. Implications for observational astrophysics are pointed out.

Weber, Fridolin [Department of Physics, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182-1233 (United States); Negreiros, Rodrigo [FIAS, Goethe University, Ruth Moufang Str 1, 60438 Frankfurt (Germany)

2011-05-24

381

Managing the star performer.  

PubMed

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

Hills, Laura

382

Superbursts from Strange Stars  

Microsoft Academic Search

Recent models of carbon ignition on accreting neutron stars predict superburst ignition depths that are an order of magnitude larger than those observed. We explore a possible solution to this problem, that the compact stars in low-mass X-ray binaries that have shown superbursts are in fact strange stars with a crust of normal matter. We calculate the properties of superbursts

Dany Page; Andrew Cumming

2005-01-01

383

Dark Stars: D\\\\  

Microsoft Academic Search

The first phase of stellar evolution in the history of the universe may be Dark Stars, powered by dark matter heating rather than by fusion. Weakly interacting massive particles, which are their own antiparticles, can annihilate and provide an important heat source for the first stars in the universe. This and the previous contribution present the story of Dark Stars.

Douglas Spolyar; Katherine Freese; Paolo Gondolo; Anthony Aguirre; Peter Bodenheimer; Jeremy A. Sellwood; Naoki Yoshida

2009-01-01

384

Dark Stars: Begynnelsen  

Microsoft Academic Search

The first phase of stellar evolution in the history of the universe may be Dark Stars, powered by dark matter heating rather than by fusion. Weakly interacting massive particles, which are their own antiparticles, can annihilate and provide an important heat source for the first stars in the universe. This and the following contribution present the story of Dark Stars.

Paolo Gondolo; Katherine Freese; Douglas Spolyar; Anthony Aguirre; Peter Bodenheimer; Jeremy A. Sellwood; Naoki Yoshida

2009-01-01

385

The Neutron Star Census  

Microsoft Academic Search

The paucity of old isolated accreting neutron stars in ROSAT observations is used to derive a lower limit on the mean velocity of neutron stars at birth. The secular evolution of the population is simulated following the paths of a statistical sample of stars for different values of the initial kick velocity, drawn from an isotropic Gaussian distribution with mean

S. B. Popov; M. Colpi; A. Treves; R. Turolla; V. M. Lipunov; M. E. Prokhorov

2000-01-01

386

Star Formation in Galaxies  

Microsoft Academic Search

Star formation on a galactic scale is regulated by the self-gravity of the gas, as shown by the Jeans-length spacing of giant cloud complexes along spiral arms and the sensitivity of the star formation rate to the gravitational stability parameter Q. Simple models based on this scenario reproduce the general properties of galactic star formation in both normal and starburst

B. G. Elmegreen

1999-01-01

387

Theory of Star Formation  

Microsoft Academic Search

We review current understanding of star formation, outlining an overall theoretical framework and the observations that motivate it. A conception of star formation has emerged in which turbulence plays a dual role, both creating overdensities to initiate gravitational contraction or collapse, and countering the effects of gravity in these overdense regions. The key dynamical processes involved in star formation---turbulence, magnetic

Christopher F. McKee; Eve C. Ostriker

2007-01-01

388

Analyzing Star Trails  

NSDL National Science Digital Library

In this activity, students examine a photograph of the night sky and answer questions about their observations. The picture, taken by a high school student in upstate New York, offers insight into the Earth's rotation, apparent star motion, the location of Polaris (the North Star), circumpolar constellations, and pointer stars.

Kluge, Steve

389

Star Trail Photography  

NSDL National Science Digital Library

This web page contains information about taking photographs of star trails, which illustrate the rotation of the Earth. The site provides techniques to take successful star trail photos, including a technique using a series of short exposures and assembling them with computer software. Techniques for including foreground images of ground objects are given. Examples of star trail photos are provided.

Peiker, E. J.

2007-10-15

390

Eclipsing Binary Stars  

NSDL National Science Digital Library

Eclipsing Binary Stars model simulates the detection of eclipsing binary stars. In this method, the light curve from the combination of the two stars, and how it changes over time due to each star transiting (or being occulted or eclipsing the other), is observed and then analyzed. In this simulation each star orbits the other in circular motion via Kepler's third law.  When one star passes in front of the other (transits), it blocks part of the starlight of the other star. This decrease in starlight is shown on the graph.  In the simulation the binary star system is shown as seen from Earth (edge on view) and from overhead, but magnified greatly, and with the star sizes not shown to the scale of the orbit. The mass, radius, and temperature of each star can be changed. The simulation uses either simple 3D or Java 3D (if installed) to render the view the stars. If Java 3D is not installed, the simulation defaults to simple 3D using Java. The Eclipsing Binary Stars model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_astronomy_eclipsing_binaries.jar file will run the program if Java is installed.

Belloni, Mario

2010-07-15

391

XRCC2 R188H (rs3218536), XRCC3 T241M (rs861539) and R243H (rs77381814) single nucleotide polymorphisms in cervical cancer risk.  

PubMed

Human Papillomavirus (HPV) is the main cause of cervical cancer and its precursor lesions. Transformation may be induced by several mechanisms, including oncogene activation and genome instability. Individual differences in DNA damage recognition and repair have been hypothesized to influence cervical cancer risk. The aim of this study was to evaluate whether the double strand break gene polymorphisms XRCC2 R188H G>A (rs3218536), XRCC3 T241M C>T (rs861539) and R243H G>A (rs77381814) are associated to cervical cancer in Argentine women. A case control study consisting of 322 samples (205 cases and 117 controls) was carried out. HPV DNA detection was performed by PCR and genotyping of positive samples by EIA (enzyme immunoassay). XRCC2 and 3 polymorphisms were determined by pyrosequencing. The HPV-adjusted odds ratio (OR) of XRCC2 188 GG/AG genotypes was OR?=?2.4 (CI?=?1.1-4.9, p?=?0.02) for cervical cancer. In contrast, there was no increased risk for cervical cancer with XRCC3 241 TT/CC genotypes (OR?=?0.48; CI?=?0.2-1; p?=?0.1) or XRCC3 241 CT/CC (OR?=?0.87; CI?=?0.52-1.4; p?=?0.6). Regarding XRCC3 R243H, the G allele was almost fixed in the population studied. In conclusion, although the sample size was modest, the present data indicate a statistical association between cervical cancer and XRCC2 R188H polymorphism. Future studies are needed to confirm these findings. PMID:23539294

Pérez, Luis Orlando; Crivaro, Andrea; Barbisan, Gisela; Poleri, Lucia; Golijow, Carlos Daniel

2013-03-29

392

Investigation of the Praesepe cluster III. Radial velocity and binarity of the F5-K0 Klein-Wassink stars  

NASA Astrophysics Data System (ADS)

Coravel observations of 103 F5-K0 stars in the Praesepe cluster yielded 24 spectroscopic binaries (3 are non-members), and 20 orbits were determined, with periods from 4 to 7400 days. Based on a complete sample in the colour range 0.40 <= B-V >= 0.80 (80 stars, including KW 244 = TX Cnc), the companion star fraction CSF = 0.45. The percentage of spectroscopic binaries with P < 1000fd is 20% (16/80). The combined photometric and spectroscopic analysis showed that 12 among 18 single-lined spectroscopic binaries are located within the `` single" star sequence in the (V,B-V) diagram and cannot be detected by the photometric analysis in the UBV system. In addition, seven photometrically analysed binaries were not detected with the radial velocity observations, but are confirmed members. The number of single:binary:triple stars is 47:30:3. Based on observations collected at the Haute-Provence Observatory (France)

Mermilliod, J.-C.; Mayor, M.

1999-12-01

393

Doppler images of the RS CVn binary II Pegasi during the years 1994-2002  

NASA Astrophysics Data System (ADS)

Aims: We publish 16 Doppler imaging temperature maps for the years 1994-2002 of the active RS CVn star II Peg. The six maps from 1999-2002 are based on previously unpublished observations. Through Doppler imaging we want to study the spot evolution of the star and in particular compare this with previous results showing a cyclic spot behaviour and persistent, active longitudes. Methods: The observations were collected with the SOFIN spectrograph at the Nordic Optical Telescope. The temperature maps were calculated using a Doppler imaging code based on Tikhonov regularization. Results: During 1994-2001, our results show a consistent trend in the derived longitudes of the principal and secondary temperature minima over time such that the magnetic structure appears to rotate somewhat more rapidly than the orbital period of this close binary. A sudden phase jump in the active region occurred between the observing seasons of 2001 and 2002. No clear trend over time is detected in the derived latitudes of the spots, indicating that the systematic motion could be related to the drift of the spot-generating mechanism rather than to differential rotation. The derived temperature maps are quite similar to the ones obtained earlier with different methods and the main differences occur in the spot latitudes and relative strength of the spot structures. Conclusions: We observe both longitude and latitude shifts in the spot activity of II Peg. However, our results are not consistent with the periodic behaviour presented in previous studies. Full Table 1 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/526/A44

Lindborg, M.; Korpi, M. J.; Hackman, T.; Tuominen, I.; Ilyin, I.; Piskunov, N.

2011-02-01

394

Evolution of variable stars  

SciTech Connect

Throughout the domain of the H R diagram lie groupings of stars whose luminosity varies with time. These variable stars can be classified based on their observed properties into distinct types such as ..beta.. Cephei stars, delta Cephei stars, and Miras, as well as many other categories. The underlying mechanism for the variability is generally felt to be due to four different causes: geometric effects, rotation, eruptive processes, and pulsation. In this review the focus will be on pulsation variables and how the theory of stellar evolution can be used to explain how the various regions of variability on the H R diagram are populated. To this end a generalized discussion of the evolutionary behavior of a massive star, an intermediate mass star, and a low mass star will be presented. 19 refs., 1 fig., 1 tab.

Becker, S.A.

1986-08-01

395

Stars main sequence  

NSDL National Science Digital Library

What happens during most of a star's life? This activity page, part of an interactive laboratory series for grades 8-12, introduces students to the main sequence phase of a star's existence. This phase is where a star lives out the majority of its life. In an interactive lab activity, students predict the length of the main sequence for four different stars. The predictions can be printed for later evaluation. Students view diagrams that compare the size and color of stars to human lives, and equilibrium within a star is stressed. Finally, students choose between two hypotheses about the length of life of a star. Students write a one- to three-sentence explanation for their hypotheses. The correct answer is provided. Copyright 2005 Eisenhower National Clearinghouse

University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

2003-01-01

396

Orbital elements of the RS CVn eclipsing binary, SV Camelopardalis  

Microsoft Academic Search

The extensiveUBV observations of SV Camelopardalis by Patkos (1982) have been analysed to derive the orbital elements of the system. The data\\u000a were corrected for the effect of third body (Sarma, Sarma & Abhyankar 1985) and for the ‘RS CVn’ distortion wave (Sarma, Vivekanandarao\\u000a & Sarma 1988). The cleaned data were used to obtain a preliminary solution by a modified

C. V. S. R. Sarma; M. B. K. Sarma; N. B. Sanwal

1989-01-01

397

Synoptic APT Photometry of the RS CVn Binary HD 28591  

Microsoft Academic Search

HD 28591 is a single-lined, non-eclipsing RS CVn binary which exhibits photometric variations indicative of starspot activity. We report on B and V observations obtained over the period 1988-1992 with the Phoenix-10 Automatic Photoelectric Telescope sited on Mt. Hopkins, AZ. The system exhibits a variable distortion wave with amplitudes ranging from 0.04 to 0.07 magnitudes in V as well as

David P. Steelman; Harold L. Nations

1992-01-01

398

Period study of the RS CVn eclipsing binary SV Camelopardalis  

Microsoft Academic Search

Using the available photographic and photoelectric times of minima, the authors have revised the elements of the light-time orbit of SV Camelopardalis, an RS CVn type eclipsing binary. Taking a mass function of 0.118 M_sun; and the inclination of 89°.84 for the eclipsing pair, the authors obtain the third body mass of 0.18, 0.21 and 0.38 M_sun; for the assumed

C. V. S. R. Sarma; M. B. K. Sarma; K. D. Abhyankar

1985-01-01

399

Engineering design of the ARIES-RS power plant  

Microsoft Academic Search

ARIES-RS is a fusion power plant design study which has examined the ability of an advanced tokamak-based power plant to compete with future energy sources and play a significant role in the future energy market. A steady-state reversed shear tokamak currently appears to offer the best combination of good economic performance and physics credibility for a tokamak-based power plant. In

M. S. Tillack

1998-01-01

400

Performance of RS codes in lognormally shadowed Rician channels  

NASA Astrophysics Data System (ADS)

The performance of Reed-Solomon (RS) codes with binary phase shift keying transmission is determined for a class of fading models for land mobile satellite communications. The fading model has the structure of a Rician model except that the line-of-sight component is subjected to a lognormal transformation. By exploiting the statistical characteristics of the multipath fading and shadowing, an effective coding/interleaving scheme is proposed.

Trabelsi, Chokri; Yongacoglu, Abbas

401

The Hydrogen Burning Turn-off of RS Ophiuchi 2006  

Microsoft Academic Search

We report a coordinated multi-band photometry of the RS Oph 2006 outburst and\\u000ahighlight the emission line free y-band photometry that shows a mid-plateau\\u000aphase at y ~ 10.2 mag from day 40 to day 75 after the discovery followed by a\\u000asharp drop of the final decline. Such mid-plateau phases are observed in other\\u000atwo recurrent novae, U Sco

Izumi Hachisu; Mariko Kato; Seiichiro Kiyota; Katsuaki Kubotera; Hiroyuki Maehara; Kazuhiro Nakajima; Yuko Ishii; Mari Kamada; Sahori Mizoguchi; Shinji Nishiyama; Naoko Sumitomo; Ken'ichi Tanaka; Masayuki Yamanaka; Kozo Sadakane

2006-01-01

402

NUDT3 rs206936 is associated with body mass index in obese Japanese women.  

PubMed

The predominant risk factor of metabolic syndrome is intra-abdominal fat accumulation, which is determined by waist circumference, waist-hip ratio measurements and visceral fat area (VFA); the latter can be accurately measured by performing computed tomography (CT). In addition to environmental factors, genetic factors play an important role in obesity and fat distribution. New genetic loci associated with body mass index (BMI) and adiposity have been identified by genome-wide association studies (GWASs). This study utilized CT to investigate whether single nucleotide polymorphisms (SNPs) that confer susceptibility to higher BMI are associated with VFA, subcutaneous fat area (SFA), and the ratio of VFA to SFA (V/S ratio). We measured the VFA and SFA of 1424 obese Japanese subjects (BMI ? 25 kg/m(2), 635 men and 789 women) who were genotyped for 13 single nucleotide polymorphisms (SNPs) reported by recent GWASs, namely, TNNI3K rs1514175, PTBP2 rs1555543, ADCY3 rs713586, IRS1 rs2943650, POC5 rs2112347, NUDT3 rs206936, LINGO2 rs10968576, STK33 rs4929949, MTIF3 rs4771122, SPRY2 rs534870, MAP2K5 rs2241423, QPCTL rs2287019, and ZC3H4 rs3810291. The G-allele of NUDT3 rs206936 was significantly associated with increased BMI (P = 5.3 × 10(-5)) and SFA (P = 0.00039) in the obese Japanese women. After adjustment with BMI, the association between rs206936 and SFA was not observed. This significant association was not observed in the men. The other SNPs analyzed were not significantly associated with BMI, VFA, SFA, or V/S ratio. Our results suggest that NUDT3 rs206936 is associated with BMI in Japanese women. PMID:23708086

Kitamoto, Aya; Kitamoto, Takuya; Mizusawa, Seiho; Teranishi, Hajime; So, Rina; Matsuo, Tomoaki; Nakata, Yoshio; Hyogo, Hideyuki; Ochi, Hidenori; Nakamura, Takahiro; Kamohara, Seika; Miyatake, Nobuyuki; Kotani, Kazuaki; Komatsu, Ryoya; Itoh, Naoto; Mineo, Ikuo; Wada, Jun; Yoneda, Masato; Nakajima, Atsushi; Funahashi, Tohru; Miyazaki, Shigeru; Tokunaga, Katsuto; Masuzaki, Hiroaki; Ueno, Takato; Chayama, Kazuaki; Hamaguchi, Kazuyuki; Yamada, Kentaro; Hanafusa, Toshiaki; Oikawa, Shinichi; Sakata, Toshiie; Tanaka, Kiyoji; Matsuzawa, Yuji; Nakao, Kazuwa; Sekine, Akihiro; Hotta, Kikuko

2013-05-25

403

Characterisation of mGluRs which modulate nociception in the PAG of the mouse  

Microsoft Academic Search

The contribution of metabotropic glutamate receptors (mGluRs) to the modulation of nociception by the periaqueductal gray (PAG) matter was investigated in mice. Intra-PAG microinjection of (1S,3R)-ACPD, an agonist of groups I and II mGluRs, as well as (S)-3,5-DHPG, a selective agonist of group I mGluRs, increased the latency of the nociceptive reaction (NR) in the hot plate test. (RS)-AIDA, an

Sabatino Maione; Ida Marabese; Juan Leyva; Enza Palazzo; Vito de Novellis; Francesco Rossi

1998-01-01

404

Massive stars, disks, and clustered star formation  

NASA Astrophysics Data System (ADS)

The formation of an isolated massive star is inherently more complex than the relatively well-understood collapse of an isolated, low-mass star. The dense, clustered environment where massive stars are predominantly found further complicates the picture, and suggests that interactions with other stars may play an important role in the early life of these objects. In this thesis we present the results of numerical hydrodynamic experiments investigating interactions between a massive protostar and its lower-mass cluster siblings. We explore the impact of these interactions on the orientation of disks and outflows, which are potentially observable indications of encounters during the formation of a star. We show that these encounters efficiently form eccentric binary systems, and in clusters similar to Orion they occur frequently enough to contribute to the high multiplicity of massive stars. We suggest that the massive protostar in Cepheus A is currently undergoing a series of interactions, and present simulations tailored to that system. We also apply the numerical techniques used in the massive star investigations to a much lower-mass regime, the formation of planetary systems around Solar- mass stars. We perform a small number of illustrative planet-planet scattering experiments, which have been used to explain the eccentricity distribution of extrasolar planets. We add the complication of a remnant gas disk, and show that this feature has the potential to stabilize the system against strong encounters between planets. We present preliminary simulations of Bondi-Hoyle accretion onto a protoplanetary disk, and consider the impact of the flow on the disk properties as well as the impact of the disk on the accretion flow.

Moeckel, Nickolas Barry

405

X-ray survey for pre-main-sequence stars in the Taurus-Auriga and Perseus molecular cloud complexes  

SciTech Connect

Seventy-five fields from the Einstein X-Ray Observatory IPC detector between 3h and 5h right ascension and 15 deg and 35 deg declination are examined to search for X-ray-emitting low-mass pre-main-sequence (PMS) stars. Six such stars were previously found; they appear to be similar to T Tauri stars but without dense circumstellar envelopes or winds. Finding charts are presented for 59 X-ray sources that may be PMS stars. While some are likely to be spurious X-ray sources, chance coincidences with unrelated stars, or non-PMS stellar sources such as RS CVn type binaries, approximately half are probably X-ray-selected PMS stars. 46 references.

Feigelson, E.D.; Jackson, J.M.; Mathieu, R.D.; Myers, P.C.; Walter, F.M.

1987-11-01

406

Different angiogenesis effect of mini-TyrRS/mini-TrpRS by systemic administration of modified siRNAs in rats with acute myocardial infarction.  

PubMed

We aimed to clarify the different angiogenesis effects of mini-tyrosyl-tRNA synthetase (TyrRS)/minitryptophanyl-tRNA synthetase (TrpRS) in rodent primates with acute myocardial infarction, by delivering small interfering RNAs (siRNAs) systemically in a liposomal formulation. Left coronary artery ligation was used to establish the model of acute myocardial infarction in rats; mini-TyrRS/mini-TrpRS-specific siRNAs were encapsulated in stable nucleic acid lipid particles (SNALP), and administered by intravenous injection to rats. Rats were divided into four experiment groups: sham operated group (no left anterior descending artery [LAD] occlusion); negative control group (LAD occlusion + saline injection); mock transfection group (LAD occlusion + mock transfected injection); experiment group (LAD occlusion + mini-TyrRS/mini-TrpRS-specific siRNAs injection). Silencing efficiency was assayed by Western blotting. To determine whether mini-TyrRS/mini-TrpRS affected the angiogenesis activity of rats with myocardial infarction, we measured the myocardial infarction size by TTC staining, and the capillary density using immunohistochemistry staining, to investigate the expression of factor VIII. The myocardial infarction size and the capillary density of mini-TyrRS-siRNA group were respectively 18.89% and 8.64/0.1 mm(2) 1 month after ligation, while in the mini-TrpRS-siRNA group these values were 7.33% and 17.32/0.1 mm(2), significantly different compared with the mock transfection group (14.19%; 13.56/0.1 mm(2)) and negative control group (14.28%; 13.89/0.1 mm(2)), P < 0.05. There were no significant changes between the mock transfection group and the negative control group, P > 0.05. These results indicated that angiogenesis is either stimulated by mini-TyrRS or inhibited by mini-TrpRS in rat models with acute myocardial infarction. PMID:20676842

Zeng, Rui; Chen, Yu-Cheng; Zeng, Zhi; Liu, Wei-Qiang; Liu, Xiao-Xia; Liu, Rui; Qiang, Ou; Li, Xian

2010-07-31

407

Many-body enhancement of positron annihilation in metals: the choice of electron density parameter rs  

Microsoft Academic Search

It is shown that the choice of electron density parameter rs, based on the electron density in the interstitial region, leads to a universal correlation between annihilation rate ( lambda ) and rs for all metals, known previously only for simple (sp) metals. This new choice of rs also gives a lower momentum dependence of the enhancement factor in Cu,

S. M. Sharma; S. K. Sikka

1984-01-01

408

A radio survey of weak T Tauri stars in Taurus-Auriga  

SciTech Connect

A multi-epoch 5 GHz survey of candidate or confirmed weak T Tauri stars in the Taurus-Auriga molecular cloud complex was conducted with the Very Large Array. The stars were chosen from those having detectable X-ray or chromospheric emission, and weak-emission-line pre-main-sequence stars found by other means. Snapshots of 99 VLA fields containing 119 candidate stars were obtained with a sensitivity of 0.7 mJy; most fields were observed on two or three dates. Nine radio sources coincident with cataloged stars were found. One may be an RS CVn binary system; the other eight are pre-main-sequence stars. Three of the detected stars - HD 283447, V410 Tau, and FK X-ray 1 - were previously known radio sources. Five new detections are Herbig's Anon 1, Hubble 4, HDE 283572, Elias 12, and HK Tau/c. At least five of the sources are variable, and no linear or circular polarization was found. Several lines of evidence suggest that the radio-detected weak T Tauri stars are quite young, perhaps younger on average than nondetected stars. 54 refs.

O'neal, D.; Feigelson, E.D.; Mathieu, R.D.; Myers, P.C. (Pennsylvania State Univ., University Park (USA) Wisconsin Univ., Madison (USA) Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (USA))

1990-11-01

409

Star Show Classroom Activity  

NSDL National Science Digital Library

In this lesson from Math Machines, the class will "plan and conduct a simulated astronomical observing session to photgraph a variety of star types." The instructor will set up several "stars" around the classroom, and students will then set up a telescope location and estimate the altitude and azimuth to photograph each star. A participant handout (including worksheet) and facilitator notes are made available for download in DOC file format. Links to calculator programs are also included.

Thomas, Fred

2011-11-03

410

Dark Stars: D\\\\\\  

Microsoft Academic Search

The first phase of stellar evolution in the history of the universe may be\\u000aDark Stars, powered by dark matter heating rather than by fusion. Weakly\\u000ainteracting massive particles, which are their own antiparticles, can\\u000aannihilate and provide an important heat source for the first stars in the\\u000auniverse. This and the previous contribution present the story of Dark Stars.

Douglas Spolyar; Katherine Freese; Paolo Gondolo; Anthony Aguirre; Peter Bodenheimer; Jeremy A. Sellwood; Naoki Yoshida

2009-01-01

411

The Neutron Stars Census  

Microsoft Academic Search

The paucity of old isolated accreting neutron stars in ROSAT observations is\\u000aused to derive a lower limit on the mean velocity of neutron stars at birth.\\u000aThe secular evolution of the population is simulated following the paths of a\\u000astatistical sample of stars for different values of the initial kick velocity,\\u000adrawn from an isotropic Gaussian distribution with mean

S. B. Popov; M. Colpi; A. Treves; R. Turolla; V. M. Lipunov; M. E. Prokhorov

1999-01-01

412

Impulsively Triggered Star Formation  

Microsoft Academic Search

I review several different modes of impulsively triggered star formation, starting with star formation in turbulent molecular\\u000a clouds, and exploring the origin of the clump mass function and the scaling relations between clump mass, radius and internal\\u000a velocity dispersion. This leads to the identification of a critical ram pres-sure for triggering rapid star formation, and\\u000a a reappraisal of the minimum

A. P. Whitworth

2003-01-01

413

Preliminary Map Star Catalog  

NASA Astrophysics Data System (ADS)

As part of an ongoing study, the Allegheny Observatory is in the process of measuring high precision, (1 milliarcsec), parallaxes and proper motions for approximately 900 stars selected at random in the northern sky. The spectral type of these stars is also being determined from UBVRI, uvby, H-Beta, and DDO photometry. This catalog represents a unique and complete statistical set of data for 900 stars of visual magnitude 6-12. A preliminary catalog will be presented.

Persinger, T.; Gatewood, G.; Castelaz, M.

1995-05-01

414

Our Super Star  

NSDL National Science Digital Library

Our star, the Sun, is an ordinary star. It is not particularly special compared to other stars in the universe; however, it is crucially important to us. As the massive energy source at the center of our solar system, the Sun is responsible for Earth's climate, weather, and life. In this lesson, students use observations, activities, and videos to learn basic facts about the Sun. Students also model the mechanics of day and night and use solar energy to make a tasty treat.

Foundation, Wgbh E.

2009-07-10

415

Star Trek Generations  

NSDL National Science Digital Library

Paramount Pictures and Viacom Online have developed a World Wide Web site to herald the upcoming motion picture Star Trek Generations. The site offers a galaxy of unique Star Trek elements for downloading, including pictures, sounds and a preview of the movie, in addition to behind-the-scenes information. Make sure to give Paramount "Your Input"- all respondents will receive a digital version of the Star Trek Generations movie poster

416

Binarity and multiperiodicity in high-amplitude ? Scuti stars  

NASA Astrophysics Data System (ADS)

We have carried out a photometric and spectroscopic survey of bright high-amplitude ? Scuti (HADS) stars. The aim was to detect binarity and multiperiodicity (or both) in order to explore the possibility of combining binary star astrophysics with stellar oscillations. Here, we present the first results for 10, predominantly southern, HADS variables. We detected the orbital motion of RS Gru with a semi-amplitude of ~6.5 kms-1 and 11.5 d period. The companion is inferred to be a low-mass dwarf star in a close orbit around RS Gru. We found multiperiodicity in RY Lep from both photometric and radial velocity data and detected orbital motion in the radial velocities with hints of a possible period of 500-700 d. The data also revealed that the amplitude of the secondary frequency is variable on the time-scale of a few years, whereas the dominant mode is stable. Radial velocities of AD CMi revealed cycle-to-cycle variations, which might be due to non-radial pulsations. We confirmed the multiperiodic nature of BQ Ind, while we obtained the first radial velocity curves of ZZ Mic and BE Lyn. The radial velocity curve and the O-C diagram of CY Aqr are consistent with the long-period binary hypothesis. We took new time series photometry on XX Cyg, DY Her and DY Peg, with which we updated their O-C diagrams.

Derekas, A.; Kiss, L. L.; Bedding, T. R.; Ashley, M. C. B.; Csák, B.; Danos, A.; Fernandez, J. M.; F?rész, G.; Mészáros, Sz.; Szabó, Gy. M.; Szakáts, R.; Székely, P.; Szatmáry, K.

2009-04-01

417

The 2006\\/2007 photometric activity of three chromospherically active stars: V2075 Cyg, FG UMa and BM CVn  

Microsoft Academic Search

We present new multiband CCD photometric observations of three chromospherically active stars with long periods (V2075 Cyg, FG UMa and BM CVn). The observations were made at the Çanakkale Onsekiz Mart University Observatory in 2006 and 2007. We analyzed BVRI (Bessell) CCD observations of these three RS CVn-type SB1 binaries with the following three steps: (i) Photometric rotation periods were

A. Erdem; E. Budding; E. Soydugan; H. Bakis; D. Dogru; S. S. Dogru; M. Tüysüz; Y. Kaçar; A. Dönmez; F. Soydugan

2009-01-01

418

Delta Scuti stars: Theory  

SciTech Connect

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

Guzik, J.A.

1998-03-01

419

PCSK1 rs6232 Is Associated with Childhood and Adult Class III Obesity in the Mexican Population  

Microsoft Academic Search

BackgroundCommon variants rs6232 and rs6235 in the PCSK1 gene have been associated with obesity in European populations. We aimed to evaluate the contribution of these variants to obesity and related traits in Mexican children and adults.Methodology\\/Principal FindingsRs6232 and rs6235 were genotyped in 2382 individuals, 1206 children and 1176 adults. Minor allele frequencies were 0.78% for rs6232 and 19.99% for rs6235.

Marisela Villalobos-Comparán; Hugo Villamil-Ramírez; Teresa Villarreal-Molina; Elena Larrieta-Carrasco; Paola León-Mimila; Sandra Romero-Hidalgo; Leonor Jacobo-Albavera; Adriana E. Liceaga-Fuentes; Francisco J. Campos-Pérez; Blanca E. López-Contreras; Teresa Tusié-Luna; Blanca E. del Río-Navarro; Carlos A. Aguilar-Salinas; Samuel Canizales-Quinteros

2012-01-01

420

Association of SNP rs17465637 on chromosome 1q41 and rs599839 on 1p13.3 with Myocardial Infarction in an American Caucasian Population  

PubMed Central

Summary Recent genome-wide single nucleotide polymorphism (SNP) association studies (GWAS) have identified a number of SNPs that were significantly associated with coronary artery disease (CAD) and myocardial infarction (MI). However, many independent replication studies in other populations are needed to unequivocally confirm the GWAS association. To assess GWAS association, we have established a case-control cohort consisting of 1,231 well-characterized MI patients and 560 controls without detectable coronary stenosis, all selected from the Cleveland Genebank population. The Genebank cohort has a sufficient power to detect the association between MI and four GWAS SNPs, including rs17465637 within the MIA3 gene, rs2943634 (intergenic), rs6922269 in MTHFD1L, and rs599839 near SORT1. SNPs were genotyped by TaqMan assays and follow-up multivariate logistic regression analysis with incorporation of significant covariates showed significant association with MI for MIA3 SNP rs17465637 (P-adj=0.0034) and SORT1 SNP rs599839 (P-adj=0.009). The minor allele G of rs599839 was also associated with a decreased LDL-C level of 5–9 mg/dL per allele, but not with HDL-C or triglyceride levels. No association for MI or lipid levels was found for SNPs rs2943634 and rs6922269 (P-adj>0.05). Our results establish two SNPs, rs17465637 in MIA3 and rs599839 near SORT1 as significant risk factors for MI in the American Genebank Caucasian population.

Wang, Annabel Z.; Li, Lin; Zhang, Bin; Shen, Gong-Qing; Wang, Qing Kenneth

2011-01-01

421

New Hydrodynamic Studies of the Explosion of RS Oph  

NASA Astrophysics Data System (ADS)

We have continued our studies of the evolution of Thermonuclear Runaways (TNR) in the accreted envelopes of massive white dwarfs (WD) and here we focus on the 2006 outburst of the Recurrent Symbiotic Nova (RN) RS Oph. RS Oph is a member of a small class of close binary systems in which the orbital period is long ( 460 d), the secondary is an M giant, and the WD is thought to be close in mass to the Chandrasekhar Limit. RS Oph explodes about every 20 years and the ejected material from the WD runs into the expanding outer layers of the M giant causing a wonderful display of "fireworks” that emit from gamma-rays to the radio. One important question is the secular evolution of the WD. Do the repeated outbursts cause the WD to gain or lose mass? If it is gaining mass, it could eventually reach the Chandrasekhar Limit and become a supernova or even a SN Ia if it can hide the hydrogen and helium in the system. We will report on our latest studies of TNRs using a variety of initial WD luminosities and mass accretion rates onto the WD (1.35 and 1.38 solar masses). We use our 1-D hydro code, NOVA, that now includes the Hix and Thielemann nuclear reaction network, the latest Iliadis reaction rate library, the Timmes equation of state, and OPAL opacities. We will report on the amount of ejected mass, ejection velocities, evolution time to explode, and the chemical composition of the ejecta. We gratefully acknowledge partial support from the DOE, NASA, and NSF for these studies.

Starrfield, Sumner; Sunayama, T.; Smith, M.; Iliadis, C.; Hix, W. R.; Timmes, F. X.; Sparks, W. M.

2009-05-01

422

Spot activity in the RS CVn binary UX arietis  

Microsoft Academic Search

Photoelectric observations of the RS CVn type non-eclipsing binary UX Arietis obtained at Nizamiah Observatory during the\\u000a observing seasons of 1975–76, 1981–82 and 1982–83 are presented. The light curve of UX Ari showed a distortion wave with an\\u000a amplitude inV varying from 0.02 mag during 1975–76 to 0.15 mag during 1982–83. An analysis of the available data shows that the

M. B. K. Sarma; B. V. N. S. Prakasa Rao

1984-01-01

423

SMAD7 Variant rs4939827 Is Associated with Colorectal Cancer Risk in Croatian Population  

PubMed Central

Background Twenty common genetic variants have been associated with risk of developing colorectal cancer (CRC) in genome wide association studies to date. Since large differences between populations exist, generalisability of findings to any specific population needs to be confirmed. Aim The aim of this study was to perform an association study between risk variants: rs10795668, rs16892766, rs3802842 and rs4939827 and CRC risk in Croatian population. Methods An association study was performed on 320 colorectal cancer cases and 594 controls recruited in Croatia. We genotyped four variants previously associated with CRC: rs10795668, rs16892766, rs3802842 and rs4939827. Results SMAD7 variant rs4939827 (18q21.1) was significantly associated with CRC risk in Croatian population. C allele was associated with a decreased risk, odds ratio (OR): 0.70 (95% CI: 0.57-0.85, P=3.5E-04). Compared to TT homozygotes, risk was reduced by 34% in heterozygotes (OR=0.66, 95% CI: 0.47-0.92) and by 52% in CC homozygotes (OR=0.48, 95% CI: 0.33-0.72). Conclusion Our results show association of rs4939827 with colorectal cancer risk in Croatian population. The higher strength of the association in comparison to other studies suggests population-specific environmental or genetic factors may be modifying the association. More studies are needed to further describe role of rs4939827 in CRC. Likely reason for failure of replication for other 3 loci is inadequate study power.

Kirac, Iva; Matosevic, Petar; Augustin, Goran; Simunovic, Iva; Hostic, Vedran; Zupancic, Sven; Hayward, Caroline; Antoljak, Natasa; Rudan, Igor; Campbell, Harry; Dunlop, Malcolm G.; Velimir Vrdoljak, Danko; Kovacevic, Dujo; Zgaga, Lina

2013-01-01

424

Global Star Formation Revisited  

NASA Astrophysics Data System (ADS)

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

Silk, Joseph; Norman, Colin

2009-07-01

425

Study of short-period RS Canum Venaticorum and W Ursae Majoris binary systems: The global nature of H. cap alpha  

SciTech Connect

I present the rotation versus emission characteristics of the H..cap alpha.. line for several short-period (P< or approx. =1/sup d/) RS CVn and W UMa binary systems. Estimates for the chromospheric emission arising from each component star were obtained by subtraction of '' nonactive'' model spectra constructed from comparison stars similar in spectral type to the component stars. Disentanglement of the emission contribution from each binary component was performed by fitting Gaussians to the subtracted profiles. Enhanced H..cap alpha.. emission compared to the nonactive comparison stars is seen on all components of the short-period RS CVn systems studied, while a similar enhancement is only typically seen on the primary components of the W-type W UMa systems. A possible correlation between L/sub Halpha//L/sub bol/ (values ranging from 3 to 16 x 10/sup -5/) and the Rossby number (the ratio between the rotational period and the convective time scale) is seen for those components showing emission. Such a correlation suggests that the H..cap alpha.. line is a good diagnostic for the study of the magnetic-related activity in late-type stellar systems. Plotting the L/sub Halpha//L/sub bol/ against a measure of the tidal amplitude of Scharlemann shows that the activity of the W UMa secondary components may be shut off by the tidal forces of the primaries. The shut-off appears in those components having a tidal amplitude > or approx. =0.02. It is, however, unclear whether the tidal damping of the differential rotation is the sole mechanism responsible for the shut-off of the H..cap alpha.. emission, as the activity damping may also be attributable to the contact nature of the W UMa systems.

Barden, S.C.

1985-08-01

426

Observing Double Stars  

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

427

Magnetism in Massive Stars  

NASA Astrophysics Data System (ADS)

Stars with mass more than 8 solar masses end their lives as neutron stars, which we mostly observe as highly magnetized objects. Where does this magnetic field come from? Such a field could be formed during the collapse, or is a (modified) remnant of a fossil field since the birth of the star, or otherwise generated by a dynamo during its lifetime in the pre-collapse stages. The answer is unknown, but traditionally magnetic massive stars should not exist since they do not have a convective layer such as the Sun. In the last decade, however, a number of magnetic massive stars have been found, which likely possess a stable field from their birth, and indirect evidence is accumulating that localized fields can indeed be generated during the main-sequence lifetime and beyond. These observational facts opened a new field of research, which is the topic of this review. Among the indirect evidence is a large range of observational phenomena among O and B stars that cannot be explained without the presence of surface magnetic fields. These phenomena include photospheric turbulence, wind clumping, cyclic wind variability observed in UV lines, other types of wind variability in optical lines, anomalous X-ray emission, and non-thermal emission in the radio region. A summary of the properties of observed magnetic massive OB stars is given and the role of magnetic fields in massive stars will be discussed, including how to identify new magnetic candidates.

Henrichs, H. F.

2012-12-01

428

Close triple star systems  

Microsoft Academic Search

Triple-star systems, especially those in which one star has very small mass, are examined. Observations that provide information about the physical nature of close systems, in particular, changes of the period of orbital revolution, are discussed. It is shown that the detection and study of these changes is best obtained by observations of the precise times of light minima in

F. B. Wood

1985-01-01

429

Hyperons in neutron stars  

SciTech Connect

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.

Glendenning, N.K.

1986-04-01

430

Carbon star effective temperatures  

Microsoft Academic Search

Possible methods for measuring the effective temperatures of individual carbon stars are discussed. Since calibrations of broad or narrow-band photometric colors is impractical at present, empirical corrections to narrow band color temperatures is the only valid procedure. The effective temperature of the star TW Oph is estimated, based on preliminary reduction of the occultation and associated photometry

S. T. Ridgway; G. H. Jacoby; R. R. Joyce; D. C. Wells

1981-01-01

431

The Violent Neutron Star  

NASA Astrophysics Data System (ADS)

Neutron stars enable us to study both the highest densities and the highest magnetic fields in the known Universe. In this article I review what can be learned about such fundamental physics using magnetar bursts. Both the instability mechanisms that trigger the bursts, and the subsequent dynamical and radiative response of the star, can be used to explore stellar and magnetospheric structure and composition.

Watts, A. L.

2012-12-01

432

Quarkonium at STAR.  

National Technical Information Service (NTIS)

The STAR detector is capable of reconstruction the J/(psi) meson in its dielectron decay channel, along with continuum dielectrons from heavy quark decay. The limitation is not instrumental--the ability of the STAR detector to identify electrons--rather, ...

T. J. LeCompte

1998-01-01

433

Stars for Navigation  

NASA Astrophysics Data System (ADS)

During World War II, stars were important navigation aids for pilots flying long night patrols. Several aspects of navigation by stars are discussed from personal experience by the author who flew Catalina aircraft over the ocean and North Africa during this period. This paper is based on a talk given to the Southland Astronomical Society.

Neave, Tom

2001-09-01

434

Party with the Stars.  

ERIC Educational Resources Information Center

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

Blaine, Lloyd

1997-01-01

435

Build Your Own Star  

NSDL National Science Digital Library

This SEED website from Schlumberger provides a simulation of the life-cycle of a star. The user chooses the initial mass and "metal" (non-hydrogen/helium) content, and the site shows how the star evolves and ultimately how it dies. The site also explains "the most famous graph in astronomy," the H-R diagram.

2007-06-12

436

Why Observe Double Stars?  

NASA Astrophysics Data System (ADS)

Like many branches of astronomy, the observation of double stars can be appreciated 5 at several levels. For those who enjoy the night sky, double stars offer some of 6 the most attractive sights around and they are particularly good in small telescopes 7 where the colours are much more obvious.

Argyle, Bob; Argyle, R. W.

437

X-ray grating spectra of RS Ophiuchi in outburst  

NASA Astrophysics Data System (ADS)

The recurrent nova RS Ophiuchi was observed five times with Chandra and XMM-Newton, on four different dates after the 2006 outburst. In the first month we detected an emission spectrum with prominent lines of H and He-like ions of metals including O, N, Si, Fe, Ne and Mg, showing a large range of plasma temperatures. At this stage the emission was originated in the red giant wind material shocked by the nova ejecta. Later spectra show a large increase in emission at longer wavelengths, peaking two months after the outburst. We attribute this to the emergence of the underlying white dwarf. Preliminary fits with NLTE white dwarf atmospheric models yield log g = 9, and T ~800,000K, appropriate a white dwarf mass of >1.2 Msolar. The constant bolometric luminosity phase was very short, less than three months, as expected for a white dwarf mass ~ 1.35 Msolar. We detected an oscillation with a period ~35 s in March and April light curves, which may be due to the spin of the white dwarf and may represents further evidence of a very massive white dwarf, pointing at RS Oph as a likely supernova Ia progenitor.

Orio, M.; Nelson, Thomas; Leibowitz, E.; Gonzalez-Riestra, R.; Mucciarelli, P.

2007-08-01

438

Observational constraints of modified Chaplygin gas in RS II brane  

NASA Astrophysics Data System (ADS)

FRW universe in RS II braneworld model filled with a combination of dark matter and dark energy in the form of modified Chaplygin gas (MCG) is considered. It is known that the equation of state (EoS) for MCG is a three-variable equation determined by A, ? and B. The permitted values of these parameters are determined by the recent astrophysical and cosmological observational data. Here we present the Hubble parameter in terms of the observable parameters ? m0, ? x0, H 0, redshift z and other parameters like A, B, C and ?. From Stern data set (12 points), we have obtained the bounds of the arbitrary parameters by minimizing the ? 2 test. The best-fit values of the parameters are obtained by 66 %, 90 % and 99 % confidence levels. Next due to joint analysis with BAO and CMB observations, we have also obtained the bounds of the parameters ( B, C) by fixing some other parameters ? and A. The best fit value of distance modulus ?( z) is obtained for the MCG model in RS II brane, and it is concluded that our model is perfectly consistent with the union2 sample data.

Ranjit, Chayan; Rudra, Prabir; Kundu, Sujata

2013-10-01

439

Observing Variable Stars  

NASA Astrophysics Data System (ADS)

Observing variable stars is one of the major contributions amateur astronomers make to science. There are 36,000 variable stars listed in the General Catalogue of Variable Stars, so it is clearly impossible for the limited number of professional observatories to target even the majority of them. That's where amateur astronomers come in - thousands of them turning their telescopes to the sky every night. Variable star observing is the most popular of "real science" activities for amateurs, and Gerry Good's book provides everything needed. The first part of the book provides a highly detailed account of the various classes of variable star, with examples, illustrations and physical descriptions. The second section covers practical aspects of observing, everything from preparation and planning, through observing techniques, to data management and reduction.

Good, Gerry A.

440

A pre-outburst signal in the long-term optical light curve of the recurrent nova RS Ophiuchi  

NASA Astrophysics Data System (ADS)

Recurrent novae are binary stars in which a white dwarf accretes matter from a less evolved companion, either a red giant or a main-sequence star. They have dramatic optical brightenings of around 5-6 mag in V in less than a day, several times a century. These occur at variable and unpredictable intervals, and are followed by an optical decline over several weeks and activity from the X-ray to the radio. The unpredictability of recurrent novae and related stellar types can hamper systematic study of their outbursts. Here we analyse the long-term light curve of RS Ophiuchi, a recurrent nova with six confirmed outbursts, most recently in 2006 February. We confirm the previously suspected 1945 outburst, largely obscured in a seasonal gap. We also find a signal via wavelet analysis that can be used to predict an incipient outburst up to a few hundred days before hand. This has never before been possible. In addition, this may suggest that the preferred thermonuclear runaway mechanism for the outbursts will have to be modified, as no pre-outburst signal is anticipated in that case. If our result indeed points to gaps in our understanding of how outbursts are driven, we will need to study such objects carefully to determine if the white dwarf is growing in mass, an essential factor if these systems are to become Type Ia supernovae. Determining the likelihood of recurrent novae being an important source population will have implications for stellar and galaxy evolution.

Adamakis, S.; Eyres, S. P. S.; Sarkar, A.; Walsh, R. W.

2011-07-01

441

Computational Star Formation (IAU S270)  

NASA Astrophysics Data System (ADS)

1. Historical introduction; 2. Individual star formation: observations; 3. Low-mass star formation: observations; 4. Individual star formation: theory; 5. Formation of clusters: observations; 6. Formation of clusters: theory; 7. Numerical methods: MHD; 8. Numerical methods: radiative dynamics; 9. Local star formation processes; 10. Star formation feedback; 11. Star formation on galactic scales; 12. Special purpose hardware; 13. Computational methods; 14. Radiation diagnostics of star formation; 15. Large scale star formation; 16. Cosmological star formation; 17. Computational star formation: Summary; Index.

Alves, João.; Elmegreen, Bruce G.; Girart, Josep M.; Trimble, Virginia

2011-05-01

442

Eclipsing Binary Stars in the OGLE-III Fields of the Small Magellanic Cloud  

NASA Astrophysics Data System (ADS)

We present a large sample of eclipsing binary stars detected in the Small Magellanic Cloud fields covering about 14 square degrees that have been monitored for eight years during the third phase of the OGLE survey. This is the largest set of such variables containing 6138 objects, of which 777 are contact and 5361 non-contact binaries. The estimated completeness of this sample is around 82%. We analyze the statistical properties of the sample and present selected interesting objects: 32 systems having eccentric orbit with visible apsidal motion, one Transient Eclipsing Binary, ten RS CVn type stars, 22 still unexplained Double-Periodic Variable stars, and 15 candidates for doubly eclipsing quadruple systems. Based on the OGLE-III proper motions, we classified 47 binaries from our sample as foreground Galactic stars. We also list candidates suitable for the SMC distance determination.

Pawlak, M.; Graczyk, D.; Soszy?ski, I.; Pietrukowicz, P.; Poleski, R.; Udalski, A.; Szyma?ski, M. K.; Kubiak, M.; Pietrzy?ski, G.; Wyrzykowski, ?.; Ulaczyk, K.; Koz?owski, S.; Skowron, J.

2013-09-01

443

Modelling of an Eclipsing RS CVn Binary: V405 And  

NASA Astrophysics Data System (ADS)

V405 And is an ultrafast-rotating (Prot ~ 0.46 days) eclipsing binary. The system consists of a primary star with radiative core and convective envelope, and a fully convective secondary. Theories have shown that stellar structure can depend on magnetic activity, i.e., magnetically active M-dwarfs should have larger radii. Earlier light curve modelling of V405 And indeed showed this behaviour: we found that the radius of the primary is significantly larger than the theoretically predicted value for inactive main sequence stars (the discrepancy is the largest of all known objects), while the secondary fits well to the mass-radius relation. By modelling our recently obtained light curves, which show significant changes of the spotted surface of the primary, we can find further proof for this phenomenon.

Vida, Krisztián; Oláh, Katalin; K?vári, Zsolt

2012-04-01

444

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

SciTech Connect

Results are reported from a 6-cm VLA survey of five confirmed Ba II stars and eight mild Ba II stars, undertaken to search for evidence of gyrosynchrotron emission or thermal emission from the primary star's wind that is enhanced or photoionized by a white dwarf companion. Of these 13 stars, only Beta UMi was detected as a possible radio source at a flux level of 0.11 mJy (3sigma). The 6-cm radio luminosities (L6) of the other stars are as small as log L6 less than or equal to 14.0 and are an order of magnitude or more lower than the average levels found in RS CVn systems, but are consistent with the L6 upper limits previously found for stars of spectral type similar to the Ba II stars and normal elemental abundances. The upper limit to the radio luminosity for the possible mild Ba II star 56 Peg, when combined with its previously known X-ray luminosity, may provide useful constraints on the various models that have been proposed for this interesting object, once its orbital period is known. 28 references.

Drake, S.A.; Simon, T.; Linsky, J.L.

1987-01-01

445

Discovery of Variable Stars in the Field of the Galactic Open Cluster NGC 7039  

NASA Astrophysics Data System (ADS)

We report variable stars identified in the field of the Galactic open cluster, NGC 7039. In the fall/winter of 2009, imaging photometry has been acquired, mainly in the R band, for eight open clusters using the 81 cm Tenagra telescope in Arizona. We present the results for our first target, NGC 7039. We have found 42 new variable stars and six suspected variable stars. Among the variable stars, there are 14 eclipsing binaries, including one RS Canum Venaticorum-type system, one RR Lyrae, two Cepheid, one ? Cephei, three ? Scuti, eight pulsatinglike stars, five variable stars with periods longer than the observation window of 41 days, and eight irregular variable stars. Two contact binary systems could be members of NGC 7039 because of their loci in the color-magnitude diagram and their distance moduli close to that of the open cluster. One of the contact binary systems shows infrared excess in the ( J - H ) and ( H - Ks ) diagrams. It could have circumstellar dust. None of the pulsating stars belong to the open cluster.

Hu, Juei-Hwa; Chen, Hui-Chen; Chen, Ying-Tung; Chang, Ding-Cheng; Lin, Hsing-Wen; Ngeow, Chow-Choong; Chen, W. P.; Ip, Wing-Huen

2011-06-01

446

Chromospheric activity in evolved stars - The rotation-activity connection and the binary-single dichotomy  

SciTech Connect

A tabulation of measured values of the Ca II H and K (S) index are transformed to the original Mount Wilson definition of the index. The tabulation includes main-sequence, evolved, single, and tidally coupled (RS CVn) binary stars. The (S) indices are analyzed against Wilson's (1976) I(HK) intensity estimates, showing that Wilson's estimates are only a two-state indicator. Ca II H and K fluxes are computed and calibrated with published values of rotation periods. It is found that the single and binary stars are consistent with a single relationship between rotation and Ca II excess emission flux. 25 refs.

Young, A.; Ajir, F.; Thurman, G. (San Diego State Univ., CA (USA))

1989-11-01

447

Project Jelly-Fish: B.R.N.O. Observations of Semiregular Variable Stars  

NASA Astrophysics Data System (ADS)

Brno Regional Network of Observers (BRNO) is a group which prefers to observe eclipsing binary stars. A team called the Jelly-Fish has been formed within BRNO for the purpose of observing variable stars other than eclipsing binaries. The observations by Jelly-Fish members are predominantly visual; CCD observing has started only recently and such observations are not yet included in our statistics. Jelly-Fish has about twenty members at this moment. This paper presents preliminary results based on Jelly-Fish observations of S Camelopardalis, AU Camelopardalis, WZ Cassiopeiae, RS Cygni, T Persei, RU Persei, and R Ursae Minoris.

Hajek, P.

2006-06-01

448

Scope on the Skies: Star light, star bright  

NSDL National Science Digital Library

In astronomy, the brightness of a star is described in terms of a star's magnitude. Stellar magnitude is expressed two different ways, using the terms apparent magnitude and absolute magnitude . For both magnitudes, the numbering scale is the same, with negative numbers being brighter stars and positive numbers being dimmer stars. This month's column sheds light on the stars and how astronomers measure distances to these celestial objects.

Riddle, Bob

2009-03-01

449

The Constellations and their Stars  

NSDL National Science Digital Library

This website is a tutorial on constellations and the stars in them. It offers an alphabetical and monthly listing of the constellations. It also provides a listing of stars, messier objects, and a list of the brightest stars in the sky. The user can also use the website's interactive star chart, Milky Way photos, or helpful links.

Dolan, Chris

2005-05-15

450

Infrared studies of star formation  

Microsoft Academic Search

Infrared observations at wavelengths of a few microns to 1 mm are reviewed which pertain to the problem of star formation. The data considered include observations of large gas and dust clouds within which stars may be forming and detailed studies of individual objects within these clouds. Stages of star formation are outlined, the IR luminosity of forming stars is

M. W. Werner; E. E. Becklin; G. Neugebauer

1977-01-01

451

Lithium in stars with exoplanets  

Microsoft Academic Search

Our recent study of solar-type stars from the HARPS GTO sample provides highly accurate information with regard to Lithium abundances in stars with and without detected planets (Israelian et al. 2009). When the Li abundances of planet bearing stars are compared with the ``single'' stars, we find an excess of Li depletion in planet hosts with effective temperatures in the

Garik Israelian

2010-01-01

452

Visual Binary Star Observations  

NASA Astrophysics Data System (ADS)

A special mathematics course (MAT298AC) was offered in the fall 2010 and spring 2011 semesters at the Estrella Mountain Community College (EMCC), providing students the opportunity to gain real-world experience through observations, applied mathematics and research techniques. The students and instructor in MAT298AC chose to pursue visual binary star observations with the goal of contributing to the scientific knowledge base. Visual observations of selected binary stars were obtained by utilizing EMCC campus astronomical equipment. Data collected includes the separation of potential binary stars and their position angle.

Darling, Kodiak; Diaz, Kristy; Lucas, Arriz; Santo, Travis; Walker, Douglas

2011-05-01

453

The Two-Component System CprRS Senses Cationic Peptides and Triggers Adaptive Resistance in Pseudomonas aeruginosa Independently of ParRS  

PubMed Central

Cationic antimicrobial peptides pass across the outer membrane by interacting with negatively charged lipopolysaccharide (LPS), leading to outer membrane permeabilization in a process termed self-promoted uptake. Resistance can be mediated by the addition of positively charged arabinosamine through the action of the arnBCADTEF operon. We recently described a series of two-component regulators that lead to the activation of the arn operon after recognizing environmental signals, including low-Mg2+ (PhoPQ, PmrAB) or cationic (ParRS) peptides. However, some peptides did not activate the arn operon through ParRS. Here, we report the identification of a new two-component system, CprRS, which, upon exposure to a wide range of antimicrobial peptides, triggered the expression of the LPS modification operon. Thus, mutations in the cprRS operon blocked the induction of the arn operon in response to several antimicrobial peptides independently of ParRS but did not affect the response to low Mg2+. Distinct patterns of arn induction were identified. Thus, the responses to polymyxins were abrogated by either parR or cprR mutations, while responses to other peptides, including indolicidin, showed differential dependency on the CprRS and ParRS systems in a concentration-dependent manner. It was further demonstrated that, following exposure to inducing antimicrobial peptides, cprRS mutants did not become adaptively resistant to polymyxins as was observed for wild-type cells. Our microarray studies demonstrated that the CprRS system controlled a quite modest regulon, indicating that it was quite specific to adaptive peptide resistance. These findings provide greater insight into the complex regulation of LPS modification in Pseudomonas aeruginosa, which involves the participation of at least 4 two-component systems.

Fernandez, Lucia; Jenssen, Havard; Bains, Manjeet; Wiegand, Irith; Gooderham, W. James

2012-01-01

454

Interannual Variability of Gravity Waves in MCS & MGS RS Data  

NASA Astrophysics Data System (ADS)

Heavens’ et al. (2010) observed within Mars Climate Sounder (MCS) vertical temperature profiles increased instances of ‘significant instabilities’ at high northern latitudes occurring within 80 degrees of Solar Longitude prior to the Mars Year (MY) 28 dust storm. Heaven’s et al. (2010) defined significant instabilities to be instances where convective available potential energy (CAPE) values for an individual vertical temperature profile exceeded 300 J/kg. The instabilities are thought to be the result of gravity (buoyancy) wave saturation. These high latitude instabilities temporally coincided with cooling at 0.1 Pa in low northern latitudes, and this cooling may be the result of gravity waves’ effect on the mean meridional circulation due to increased horizontal momentum deposition. With more data from MY 30 available we expand upon their analysis. We also explore whether the increased instances of significant instabilities can be explained by increased wave activity or changes in the background wind and thermal environment limiting the vertical propagation of gravity waves. An analysis of gravity wave activity is explored by investigating interannual variability of gravity wave energies using techniques similar to Creasey et al.’s (2006) analysis of Mars Global Surveyor (MGS) Radio Science (RS) vertical temperature data. We further explore the effect of the background wind and thermal environment on the vertical propagation of gravity waves by investigating the Scorer parameter. Vertical changes in the Scorer parameter have an ability to affect the vertical propagation of terrain generated gravity waves. This analysis may show that changes in the background wind and thermal environment may have allowed vertical propagation of gravity waves to produce the observed instabilities prior to the MY 28 dust storm. Similar analysis of the MGS RS vertical temperature data is conducted searching for further variability in gravity wave activity before the MY 25 dust storm.

Edmonds, Robert; Murphy, J.

2012-10-01

455

Functional Analysis of Deep Intronic SNP rs13438494 in Intron 24 of PCLO Gene.  

PubMed

The single nucleotide polymorphism (SNP) rs13438494 in intron 24 of PCLO was significantly associated with bipolar disorder in a meta-analysis of genome-wide association studies. In this study, we performed functional minigene analysis and bioinformatics prediction of splicing regulatory sequences to characterize the deep intronic SNP rs13438494. We constructed minigenes with A and C alleles containing exon 24, intron 24, and exon 25 of PCLO to assess the genetic effect of rs13438494 on splicing. We found that the C allele of rs13438494 reduces the splicing efficiency of the PCLO minigene. In addition, prediction analysis of enhancer/silencer motifs using the Human Splice Finder web tool indicated that rs13438494 induces the abrogation or creation of such binding sites. Our results indicate that rs13438494 alters splicing efficiency by creating or disrupting a splicing motif, which functions by binding of splicing regulatory proteins, and may ultimately result in bipolar disorder in affected people. PMID:24167553

Seo, Seunghee; Takayama, Kanako; Uno, Kyosuke; Ohi, Kazutaka; Hashimoto, Ryota; Nishizawa, Daisuke; Ikeda, Kazutaka; Ozaki, Norio; Nabeshima, Toshitaka; Miyamoto, Yoshiaki; Nitta, Atsumi

2013-10-22

456

Establishing a Three Rs programme at the Canadian Council on Animal Care.  

PubMed

The anniversary of the Fund for the Replacement of Animals in Medical Experiments (FRAME) provides an opportunity to celebrate the Charity's achievements over the past 40 years, and in particular, its contribution to the international acceptance of the Three Rs as the basis of an ethic for animal experimentation, and its role as a leader in the implementation of the Three Rs in the life sciences. The Canadian Council on Animal Care (CCAC) has based its work on the Three Rs, especially since the establishment of its fundamental CCAC Policy Statement on the Ethics of Animal Investigation (1989). Following recommendations from the evaluation of its programmes by external committees established by the national granting agencies, the CCAC recently launched a Three Rs Program. This programme will build on the work of FRAME and other similar Three Rs organisations, to further the promotion and implementation of the Three Rs in Canadian science. PMID:20105015

Griffin, Gilly

2009-12-01

457

Functional Analysis of Deep Intronic SNP rs13438494 in Intron 24 of PCLO Gene  

PubMed Central

The single nucleotide polymorphism (SNP) rs13438494 in intron 24 of PCLO was significantly associated with bipolar disorder in a meta-analysis of genome-wide association studies. In this study, we performed functional minigene analysis and bioinformatics prediction of splicing regulatory sequences to characterize the deep intronic SNP rs13438494. We constructed minigenes with A and C alleles containing exon 24, intron 24, and exon 25 of PCLO to assess the genetic effect of rs13438494 on splicing. We found that the C allele of rs13438494 reduces the splicing efficiency of the PCLO minigene. In addition, prediction analysis of enhancer/silencer motifs using the Human Splice Finder web tool indicated that rs13438494 induces the abrogation or creation of such binding sites. Our results indicate that rs13438494 alters splicing efficiency by creating or disrupting a splicing motif, which functions by binding of splicing regulatory proteins, and may ultimately result in bipolar disorder in affected people.

Seo, Seunghee; Takayama, Kanako; Uno, Kyosuke; Ohi, Kazutaka; Hashimoto, Ryota; Nishizawa, Daisuke; Ikeda, Kazutaka; Ozaki, Norio; Nabeshima, Toshitaka; Miyamoto, Yoshiaki; Nitta, Atsumi

2013-01-01

458

Possible Nova among Hyades stars  

NASA Astrophysics Data System (ADS)

A new(?) very red 6th mag star was discovered among the stars of the Hyades from images obtained on 2012 October 22 04:28 EDT (10:28 UT). The coordinates of the star are RA,Dec (J2000.0): 04:23:29, +17:58:29 (+/-10"). This position is 2.23 arcmin south of the star GSC 1268-1045; and although this faint (13th mag) star does not appear on the discovery images, it is not believed to be the new star. Follow-up observations, especially spectroscopy are very desirable to confirm the presence and nature of the new star.

Shelton, Ian

2012-10-01

459

Pharmacological characterization of two novel and potent 5-HT4 receptor agonists, RS 67333 and RS 67506, in vitro and in vivo.  

PubMed Central

1. The pharmacology of two novel 5-HT4 receptor agonists, RS 67333 (1-(4-amino-5-chloro-2-methoxy-phenyl)-3-[1(n-butyl)-4-piperidinyl]-1- propanone HCl) and RS 67506 (1-(4-amino-5-chloro-2-methoxy-phenyl)-3-[1-(2-methyl sulphonylamino)ethyl-4-piperidinyl]-1-propanone HCl) have been assessed in vitro and in vivo. 2. RS 67333 and RS 67506 exhibited affinities (pKi = 8.7 and 8.8, respectively) for the 5-HT4 binding sites, labelled with [3H]-GR 113808, in guinea-pig striatum. The Hill coefficients from these displacement curves were not significantly different from unity. The compounds exhibited lower affinities (< 6.0) at several other receptors including 5-HT1A, 5-HT1D, 5-HT2A, 5-HT2C, dopamine D1, D2 and muscarinic M1-M3 receptors. However, RS 67333 and RS 67506 did exhibit affinities for the sigma 1 (pKi = 8.9 and 7.9, respectively) and sigma 2 (pKi = 8.0 and 7.3, respectively) binding sites. 3. At the 5-HT4 receptor mediating relaxation of the carbachol-precontracted oesophagus, RS 67333 and RS 67506 acted as potent (pEC50 8.4 and 8.6, respectively), partial agonists (intrinsic activities, with respect to 5-HT were 0.5 and 0.6, respectively) with respect to 5-HT. Relaxant responses to RS 67333 or RS 67506 were surmountably antagonized by GR 11308 (10 nM), with apparent affinities (pKB) of 9.1 and 9.0, respectively. RS 67333 and RS 67506 induced dose-dependent increases in heart rate of the anaesthetized micropig (ED50 4.9 and 5.4 micrograms kg-1, i.v.), with maximal increases of 35 and 47 beats min-1, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Eglen, R. M.; Bonhaus, D. W.; Johnson, L. G.; Leung, E.; Clark, R. D.

1995-01-01

460

Association of PCSK1 rs6234 with Obesity and Related Traits in a Chinese Han Population  

Microsoft Academic Search

BackgroundCommon variants in PCSK1 have been reported to be associated with obesity in populations of European origin. We aimed to replicate this association in Chinese.Methodology\\/Principal FindingsTwo PCSK1 variants rs6234 and rs6235 (in strong LD with each other, r2 = 0.98) were genotyped in a population-based cohort of 3,210 Chinese Hans. The rs6234 was used for further association analyses with obesity

Qibin Qi; Huaixing Li; Ruth J. F. Loos; Chen Liu; Frank B. Hu; Hongyu Wu; Zhijie Yu; Xu Lin; Cuilin Zhang

2010-01-01

461

A near-infrared shock wave in the 2006 outburst of recurrent nova RS Ophiuchi  

Microsoft Academic Search

Near-infrared spectra are presented for the recent 2006 outburst of the\\u000arecurrent nova RS Ophiuchi (RS Oph).We report the rare detection of an infrared\\u000ashock wave as the nova ejecta plows into the pre-existing wind of the secondary\\u000ain the RS Oph system consisting of a white dwarf (WD) primary and a red giant\\u000asecondary. The evolution of the shock

Ramkrishna Das; Dipankar P. K. Banerjee; Nagarhalli M. Ashok

2006-01-01

462

Variation in the Group B Streptococcus CsrRS Regulon and Effects on Pathogenicity  

Microsoft Academic Search

CsrRS (or CovRS) is a two-component regulatory system that controls expression of multiple virulence factors in the important human pathogen group B Streptococcus (GBS). We now report global gene expression studies in GBS strains 2603V\\/R and 515 and their isogenic csrR and csrS mutants. Together with data reported previously for strain NEM316, the results reveal a conserved 39-gene CsrRS regulon.

Sheng-Mei Jiang; Nadeeza Ishmael; Julie Dunning Hotopp; Manuela Puliti; Luciana Tissi; Nikhil Kumar; Michael J. Cieslewicz; H. Tettelin; Michael R. Wessels

2008-01-01

463

The salt stress relief and growth promotion effect of Rs5 on cotton  

Microsoft Academic Search

The effect of the Rs-5 bacteria strain, identified as Klebsiella oxytoca and isolated with ACC as the sole nitrogen source, on salt stressed cotton seedling growth was studied. It was demonstrated\\u000a that Rs-5 could obviously relieve salt stress and promote cotton seedling growth. After treatment with Rs-5, the individual\\u000a plant height and dry weight of cotton increased by 14.9 and

Haitao Yue; Wenping Mo; Chun Li; Yuanyuan Zheng; Hui Li

2007-01-01

464

A Study of the Coronal Plasma in RS CVn binary systems: HR 1099 and co  

Microsoft Academic Search

XMM-Newton has been performing comprehensive studies of X-ray luminous RS CVn\\u000abinary systems in its calibration and guaranteed time programs. We present\\u000aresults from ongoing investigations in the context of a systematic study of\\u000acoronal emission from RS CVns. We concentrate here on coronal abundances and\\u000ainvestigate the abundance pattern in RS CVn binaries as a function of activity\\u000aand

F. Favata; J. J. Drake; M. Audard; M. Gudel; A. Sres; R. Mewe; A. J. J. Raassen; E. Behar

2001-01-01

465

Efficient module-based modeling for a large-scale AS\\/RS-AGV system  

Microsoft Academic Search

A method of modeling large-scale AS\\/RS-AGV systems is proposed in an attempt to describe the AS\\/RS precisely and flexibly in which a lot of items are stored and retrieved. The system considered in this study consists of the large-scale AS\\/RS with stacker cranes, the looped track AGV system, aisle conveyors connecting these two systems, and incoming and outgoing conveyors. There

Soemon Takakuwa

1996-01-01

466

Flexible modeling and analysis of large-scale AS\\/RS-AGV systems  

Microsoft Academic Search

A method of modeling large-scale AS\\/RS-AGV systems is proposed in an attempt to describe the AS\\/RS precisely and flexibly in which a lot of items are stored and retrieved. The system considered in this study consists of the large-scale AS\\/RS with stacker cranes, the looped-track AGV system, aisle conveyors connecting these two systems, and incoming and outgoing conveyors. There are

Soemon Takakuwa

1995-01-01

467

INSIG2 gene rs7566605 polymorphism is associated with severe obesity in Japanese  

Microsoft Academic Search

The single nucleotide polymorphism (SNP) rs7566605 in the upstream region of the insulin-induced gene 2 (INSIG2) is associated with the obesity phenotype in many Caucasian populations. In Japanese, this association with the obesity phenotype\\u000a is not clear. To investigate the relationship between rs7566605 and obesity in Japanese, we genotyped rs7566605 from severely\\u000a obese subjects [n = 908, body mass index

Kikuko Hotta; Michihiro Nakamura; Yoshio Nakata; Tomoaki Matsuo; Seika Kamohara; Kazuaki Kotani; Ryoya Komatsu; Naoto Itoh; Ikuo Mineo; Jun Wada; Hiroaki Masuzaki; Masato Yoneda; Atsushi Nakajima; Shigeru Miyazaki; Katsuto Tokunaga; Manabu Kawamoto; Tohru Funahashi; Kazuyuki Hamaguchi; Kentaro Yamada; Toshiaki Hanafusa; Shinichi Oikawa; Hironobu Yoshimatsu; Kazuwa Nakao; Toshiie Sakata; Yuji Matsuzawa; Kiyoji Tanaka; Naoyuki Kamatani; Yusuke Nakamura

2008-01-01

468

Variable star data online  

NASA Astrophysics Data System (ADS)

Roger Pickard, Andy Wilson and Gary Poyner describe the online database of the British Astronomical Association Variable Star Section, a treasure trove of observations stretching back nearly 125 years.

Pickard, Roger; Wilson, Andy; Poyner, Gary

2012-06-01

469

Detector limitations, STAR.  

National Technical Information Service (NTIS)

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 li...

D. G. Underwood

1998-01-01

470

Cosmions and stars  

SciTech Connect

Hypothetical particles such as the heavy neutrino, the photino, or the sneutrino/emdash/generically called cosmions/emdash/may solve the so called missing mass problem. If they exist, the cosmions may close the Universe. In addition to their gravitational effect on cosmological scales, the cosmions may also be captured by stars and concentrate in their cores. Since cosmions are able to transport heat outside stellar cores much more efficiently than photons, they may seriously affect the thermodynamics of the inner layer of stars. We have done an exact calculation of the accretion rate of cosmions by main sequence stars and we have studied the suppression of their central convection. We concluded that central convection inside stars between 0.3 Msub solar and 1 Msub solar is broken in the presence of cosmions. 6 refs., 2 figs.

Salati, P.

1987-12-01

471

Structure of Neutron Stars.  

National Technical Information Service (NTIS)

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 semiem...

C. K. Cheong

1974-01-01

472

Inside a Star . . .  

ERIC Educational Resources Information Center

|Describes classroom activities to understand the evolution of elements as it occurs in the stars. Activities can be undertaken in groups. Explicit instructions and background materials are included. (PS)|

Akerman, Jane; Wentzel, Donat G.

1973-01-01

473

AM CVn stars  

Microsoft Academic Search

I review our observational and theoretical knowledge of AM CVn stars,\\u000afocusing on recent developments. These include newly discovered systems, the\\u000apossibility that two recently discovered extremely short period objects are AM\\u000aCVn stars and an update on X-ray, UV an optical studies. Theoretical advances\\u000ainclude the study of the details of both the donor and accretor, and the\\u000aphysics

Gijs Nelemans

2004-01-01

474

The Bibliographical Star Index  

NASA Astrophysics Data System (ADS)

The Bibliographical Star Index (BSI) is a bibliographical survey of astrophysical papers on stars that were published in 12 journals from 1950 to 1972 or have been published in about 40 journals since 1972. Difficulties that prevented complete coverage of the stellar literature are discussed, along with limitations of and errors in the BSI. The contents of the BSI for the period from 1950 to 1978 are summarized, and the availability of the index is briefly noted.

Ochsenbein, F.

475

SSE: Single Star Evolution  

NASA Astrophysics Data System (ADS)

SSE is a rapid single-star evolution (SSE) code; these analytical formulae cover all phases of evolution from the zero-age main-sequence up to and including remnant phases. It is valid for masses in the range 0.1-100 Msun and metallicity can be varied. The SSE package contains a prescription for mass loss by stellar winds. It also follows the evolution of rotational angular momentum for the star.

Hurley, Jarrod R.; Pols, Onno R.; Tout, Christopher A.

2013-03-01

476

What Drives Star Formation?  

Microsoft Academic Search

Current theoretical models for what drives star formation (especially low-mass star formation) are: (1) magnetic support of self-gravitating clouds with ambipolar diffusion removing support in cores and triggering collapse, and (2) compressible turbulence forming self-gravitating clumps that collapse as soon as the turbulent cascade produces insufficient turbulent support. A crucial observational difference between the two models is the mass to

R. M. Crutcher

2003-01-01

477

Reaching for the STARs  

Microsoft Academic Search

\\u000a The prototype STAR (Signal Transduction and Activation of RNA) protein is Sam68, the Src-associated substrate during mitosis of 68 kDa. Sam68, like all other STAR proteins, belongs to the large class of heteronuclear ribonucleoprotein particle K (hnRNP\\u000a K) homology (KH) domain family of RNA-binding proteins. The KH domain is an evolutionarily conserved RNA binding domain that\\u000a consists of 70–100 amino

Stéphane Richard

478

Physics and Star Trek  

NSDL National Science Digital Library

Created and maintained by physicist Jason Hinson, the Physics and Star Trek Web site investigates faster than light travel and subspace physics. Each topic is presented as a mix of factual information along with speculation on the author's part on how these phenomena could or could not work. Although the site consists of much text and few graphics, which may turn away some potential readers, the interesting subject will definitely appeal to hard core Star Trek or physics junkies.

1999-01-01

479

Post-AGB Stars  

NASA Astrophysics Data System (ADS)

In this contribution, a review is presented on the ample data obtained on post-AGB stars, both on the central stars and their circumstellar material. The fast evolutionary phase is characterized by a rapid change in the properties of the objects, but the variety is so large that there is yet no clear consensus on how the detailed studies of individual objects are linked together by evolutionary channels. The absence of strong molecular veiling in the photospheres of the central stars, together with a spread in intrinsic metallicity make post-AGB stars very useful in constraining AGB chemical evolutionary models. We discuss the surprisingly wide variety of chemical signatures observed. The onset in the creation process of the panoply of structures and shapes observed in planetary nebulae occurs during the short post-AGB evolution, but the physical nature of the processes involved is still badly understood. In the rapidly growing field of circumstellar mineralogy, post-AGB stars have their story to tell and also the molecular envelope changes significantly due to dilution and hardening of the stellar radiation. The real-time evolution of some objects suffering a late thermal flash is reviewed and their possible link to other hydrogen-deficient objects is discussed. Any review on stellar evolution has a section on binaries and this contribution is no exception because binaries make up a significant fraction of the post-AGB stars known to date.

van Winckel, Hans

480

The Star*s Family - an Update  

NASA Astrophysics Data System (ADS)

We shall present the current situation of the Star*s Family, a growing collection of products: directories, dictionaries, databases, data sets, and so on. The directories gather together all practical data available on organizations involved in astronomy, space sciences and related fields, while the dictionaries concern abbreviations, acronyms, contractions and symbols encountered in the same fields. The databases correspond both to the dictionaries and directories. They are currently accessible on line at the European Southern Observatory (ESO) through Starcat and at the European Space Agency (ESA) through ESIS. Their implementation is presently carried out at Strasbourg astronomical Data Center (CDS). Other agreements are currently being negociated. Practical information on the availability of all products can be obtained from the author (telefax: +33-88491255).

Heck, Andre

1993-05-01

481

A fast star image extraction algorithm for autonomous star sensors  

NASA Astrophysics Data System (ADS)

Star sensors have been developed to acquire accurate orientation information in recent decades superior to other attitude measuring instruments. A star camera takes photos of the night sky to obtain star maps. An important step to acquire attitude knowledge is to compare the features of the observed stars in the maps with those of the cataloged stars using star identification algorithms. To calculate centroids of the star images before this step, they are required to be extracted from the star maps in advance. However, some large or ultra large imaging detectors are applied to acquire star maps for star sensors with the development of electronic imaging devices. Therefore, star image extraction occupies more and more portions of the whole attitude measurement period of time. It is required to shorten star image extraction time in order to achieve higher response rate. In this paper, a novel star image extraction algorithm is proposed which fulfill the tasks efficiently. By scanning star map, the pixels brighter than the gray threshold are found and their coordinates and brightness are stored in a cross-linked list. Data of these pixels are linked by pointers, while other pixels are neglected. Therefore, region growing algorithm can be used by choosing the first element in the list as a starting seed. New seeds are founded if the neighboring pixels are brighter than the threshold, and the last seed is deleted from the list. Next search continues until no neighboring pixels are in the list. At that time, one star image is extracted, and its centroid is calculated. Likely, other star images may be extracted, and then the examined seeds are deleted which are never considered again. A new star image search always begins from the first element for avoiding unnecessary scanning. The experiments have proved that for a 1024×1024 star map, the image extraction tak