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1

RS CVn stars - Chromospheric phenomena  

NASA Technical Reports Server (NTRS)

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.

1983-01-01

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

Beryllium abundances in parent stars of extrasolar planets: 16 Cyg A & B and rho 1 Cnc  

E-print Network

The Be II 3131 A doublet has been observed in the solar-type stars 16 Cyg A & B and in the late G-type star rho 1 Cnc, to derive their beryllium abundances. 16 Cyg A & B show similar (solar) beryllium abundances while 16 Cyg B, which has been proposed to have a planetary companion of ~2 M_Jup, is known to be depleted in lithium by a factor larger than 6 with respect to 16 Cyg A. Differences in their rotational histories which could induce different rates of internal mixing of material, and the ingestion of a similar planet by 16 Cyg A are discussed as potential explanations. The existence of two other solar-type stars which are candidates to harbour planetary-mass companions and which show lithium and beryllium abundances close to those of 16 Cyg A, requires a more detailed inspection of the peculiarities of the 16 Cyg system. For rho 1 Cnc, which is the coolest known object candidate to harbour a planetary-mass companion (M > 0.85 M_Jup), we establish a precise upper limit for its beryllium abundance, showing a strong Be depletion which constrains the available mixing mechanisms. Observations of similar stars without companions are required to asses the potential effects of the planetary companion on the observed depletion. It has been recently claimed that rho 1 Cnc appears to be a subgiant. If this were the case, the observed strong Li and Be depletions could be explained by a dilution process taking place during its post-main sequence evolution.

R. J. Garcia Lopez; M. R. Perez de Taoro

1998-03-03

4

NEWS & VIEWS nEutRon StaRS  

E-print Network

NEWS & VIEWS nEutRon StaRS a magnetar by another name Fernando Camilo is at the Columbia-mail: fernando@astro.columbia.edu O n a dark night you can see a thousand stars above, each like the Sun shining by means of nuclear fusion. Every one hundred years, one of the most massive of 1011 such stars in our

Loss, Daniel

5

Quiescent and Flaring Structure in RS Canum Venaticorum Stars  

Microsoft Academic Search

Four of the most active RS CVn stars (V711 Tau, II Peg, sigma 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 (lambdalambda70-740) and light curves (lambdalambda75-175) have been analyzed to provide emission measure distributions (EMD)

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

2002-01-01

6

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

7

Elemental abundance analyses with Coudé Echelle spectrograms from the TÜB?TAK National Observatory of Turkey: I. The HgMn stars 11 Per, HR 2801, and ? Cnc  

NASA Astrophysics Data System (ADS)

Using coadded spectrograms taken with the Coudé Echelle Spectrograph (CES) of the 1.50-m Russian-Turkish Telescope of the TÜB?TAK National Observatory (TUG) near Antalya in Turkey, elemental abundance analyses of three HgMn stars 11 Per, HR 2801, and ? Cnc were performed. Comparisons are made with spectra obtained with the long camera of the Dominion Astrophysical Observatory (DAO) coudé spectrograph and its SITe4 CCD. The CES equivalent widths are about 12% larger than that for the DAO long camera. Our first results from TUG data/spectra show that all three stars exhibit the Hg II ?3984 line and somewhat diverse abundance patterns. 11 Per tends to have underabundant light elements with underabundant and overabundant Fe-peak elements. HR 2801 has mostly underabundant elements, with a few elements having solar abundances while N and Mn are overabundant. The coolest star ? Cnc has light elements having mostly solar abundances, overabundant iron group abundances, and very overabundant SrYZr and Ba. Comparisons with the abundance patterns of other HgMn stars show that they have a wide diversity of abundance patterns. Tables 2 and 6 are available at the CDS via http://cdsarc.u-strasbg.fr/cgi-bin/qcat?J/AN/331/785.

Adelman, S. J.; Yüce, K.

2010-08-01

8

Spot activity of the RS Canum Venaticorum star ? Geminorum  

NASA Astrophysics Data System (ADS)

Aims: We model the photometry of RS CVn star ? Geminorum to obtain new information on the changes of the surface starspot distribution, that is, activity cycles, differential rotation, and active longitudes. Methods: We used the previously published continuous period search (CPS) method to analyse V-band differential photometry obtained between the years 1987 and 2010 with the T3 0.4 m Automated Telescope at the Fairborn Observatory. The CPS method divides data into short subsets and then models the light-curves with Fourier-models of variable orders and provides estimates of the mean magnitude, amplitude, period, and light-curve minima. These light-curve parameters are then analysed for signs of activity cycles, differential rotation and active longitudes. Results: We confirm the presence of two previously found stable active longitudes, synchronised with the orbital period Porb = 19.60d, and found eight events where the active longitudes are disrupted. The epochs of the primary light-curve minima rotate with a shorter period Pmin,1 = 19.47d than the orbital motion. If the variations in the photometric rotation period were to be caused by differential rotation, this would give a differential rotation coefficient of ? ? 0.103. Conclusions: The presence of two slightly different periods of active regions may indicate a superposition of two dynamo modes, one stationary in the orbital frame and the other one propagating in the azimuthal direction. Our estimate of the differential rotation is much higher than previous results. However, simulations show that this may be caused by insufficient sampling in our data. Analysed photometry and numerical results are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/562/A107

Kajatkari, P.; Hackman, T.; Jetsu, L.; Lehtinen, J.; Henry, G. W.

2014-02-01

9

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

10

Theoretical studies of the RS cannum venaticorum stars  

NASA Technical Reports Server (NTRS)

Four areas of research were investigated: chromospheric modelling; starspot modelling; supersonic transition locus (STL) crossing; and STL crossing and T Tauri phenomena. Relationships among these areas of research are presented. Stellar structure and mass ejection for these stars were examined along with chromospheric analysis.

Mullan, D. J.

1981-01-01

11

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

12

CNC router modernization  

E-print Network

A large-format CNC router has been stored in the Pappalardo Laboratory wood shop for several years in an unusable state. A need assessment determined that it would be cost effective to bring the router online for use in ...

Doody, Aaron L. (Aaron Lee)

2007-01-01

13

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

NASA Astrophysics Data System (ADS)

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. They are attributed to coherent mechanisms such as an electron-cyclotron maser or coherent plasma radiation. If the electron-cyclotron maser emits at the second or third harmonic gyrofrequency, the coronal magnetic field strength equals 250 G or 167 G, and constraints on the plasma frequency imply an electron density of 6 x 10 to the 9th/cu cm. Radio spikes from AD Leonis and Wolf 424 have rise times less than or equal to 5 ms, indicating a linear size of less than or equal to 1.5 x 10 to the 8th 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.

Lang, Kenneth R.

14

Discovery of non-radial pulsations in the spectroscopic binary Herbig Ae star RS Chamaeleontis  

NASA Astrophysics Data System (ADS)

Context: To understand the origin of stellar activity in pre-main-sequence Herbig Ae/Be stars and to get a deeper insight into the interior of these enigmatic stars, the pulsational instability strip of Palla and Marconi is investigated. In this article we present a first discovery of non radial pulsations in the Herbig Ae spectroscopic binary star RS Cha. Aims: The goal of the present work is to detect non-radial pulsations in a Herbig Ae star for the first time directly by spectrographic means and to identify the largest amplitude pulsation modes. Methods: The spectroscopic binary Herbig Ae star RS Cha was monitored in quasi-continuous observations during 14 observing nights (Jan. 2006) at the 1 m Mt. John (New Zealand) telescope with the Hercules high-resolution echelle spectrograph. The cumulative exposure time on the star was 44 h, corresponding to 255 individual high-resolution echelle spectra with R = 45 000. Least-square deconvolved spectra (LSD) were obtained for each spectrum, representing the effective photospheric absorption profile modified by pulsations. Difference spectra were calculated by subtracting rotationally broadened artificial profiles, these residual spectra were analysed and non-radial pulsations detected. A subsequent analysis with two complementary methods, namely Fourier Parameter Fit (FPF) and Fourier 2D (F2D) has been performed and first constraints on the pulsation modes derived. Results: For the very first time, we discovered by direct observational means using high-resolution echelle spectroscopy, non-radial oscillations in a Herbig Ae star. In fact, both components of the spectroscopic binary are Herbig Ae stars and both show NRPs. The FPF method identified 2 modes for the primary component with (degree ?, azimuthal order m) couples ordered by decreasing probability: f1 = 21.11 d-1 with (?, m) = (11, 11), (11, 9) or (10, 6) and f2 = 30.38 d-1 with (?, m) = ( 10, 6) or (9, 5). The F2D analysis indicates for f1 a degree ? = 8-10. For the secondary component, the FPF method identified 3 modes with (?,m) ordered by decreasing probability: f1 = 12.81 d-1 with (?, m) = (2, 1) or (2, 2), f_2b = 19.11 d-1 with (?, m) = (13, 5) or (10, 5) and f3 = 24.56 d-1 with (?, m) = (6, 3) or (6,5). The F2D analysis indicates for f1 a degree ? = 2 or 3, but proposes a contradictory identification of f_2b as a radial pulsation (? = 0). Based on observations collected at the 1 m McLellan telescope at Mt John, NZ.

Böhm, T.; Zima, W.; Catala, C.; Alecian, E.; Pollard, K.; Wright, D.

2009-04-01

15

Discovery of non-radial pulsations in the spectroscopic binary Herbig Ae star RS Cha  

E-print Network

In this article we present a first discovery of non radial pulsations in both components of the Herbig Ae spectroscopic binary star RS Cha. The binary was monitored in quasi-continuous observations during 14 observing nights (Jan 2006) at the 1m Mt John (New Zealand) telescope with the Hercules high-resolution echelle spectrograph. The cumulated exposure time on the star was 44 hrs, corresponding to 255 individual high-resolution echelle spectra with $R = 45000$. Least square deconvolved spectra (LSD) were obtained for each spectrum representing the effective photospheric absorption profile modified by pulsations. Difference spectra were calculated by subtracting rotationally broadened artificial profiles; these residual spectra were analysed and non-radial pulsations were detected. A subsequent analysis with two complementary methods, namely Fourier Parameter Fit (FPF) and Fourier 2D (F2D) has been performed and first constraints on the pulsation modes have been derived. In fact, both components of the spect...

Böhm, T; Catala, C; Alecian, E; Pollard, K; Wright, D

2008-01-01

16

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

NASA Astrophysics Data System (ADS)

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.

Zeilik, M.; Cox, D. A.; de Blasi, C.; Rhodes, M.; Budding, E.

1989-10-01

17

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

18

Discovery of non-radial pulsations in the spectroscopic binary Herbig Ae star RS Cha  

E-print Network

In this article we present a first discovery of non radial pulsations in both components of the Herbig Ae spectroscopic binary star RS Cha. The binary was monitored in quasi-continuous observations during 14 observing nights (Jan 2006) at the 1m Mt John (New Zealand) telescope with the Hercules high-resolution echelle spectrograph. The cumulated exposure time on the star was 44 hrs, corresponding to 255 individual high-resolution echelle spectra with $R = 45000$. Least square deconvolved spectra (LSD) were obtained for each spectrum representing the effective photospheric absorption profile modified by pulsations. Difference spectra were calculated by subtracting rotationally broadened artificial profiles; these residual spectra were analysed and non-radial pulsations were detected. A subsequent analysis with two complementary methods, namely Fourier Parameter Fit (FPF) and Fourier 2D (F2D) has been performed and first constraints on the pulsation modes have been derived. In fact, both components of the spectroscopic binary are Herbig Ae stars and both show NRPs. The FPF method identified 2 modes for the primary component with (degree l, azimuthal number m) couples ordered by decreasing probability: f_1 = 21.11 c/d with (l,m) = (11,11), (11,9) or (10,6) and f_2 = 30.38 c/d with (l,m) = (10,6) or (9,5). The F2D analysis indicates for f_1 a degree l = 8-10. For the secondary component, the FPF method identified 3 modes with (l,m) ordered by decreasing probability: f_1 = 12.81 c/d with (l,m) = (2,1) or (2,2), f_2b = 19.11 c/d with (l,m) = (13,5) or (10,5) and f_3 = 24.56 c/d with (l,m) = (6,3) or (6,5). The F2D analysis indicates for f_1 a degree l = 2 or 3, but proposes a contradictory identification of f_2 as a radial pulsation (l = 0).

T. Böhm; W. Zima; C. Catala; E. Alecian; K. Pollard; D. Wright

2008-12-22

19

Rotational modulation and flares on RS Canum Venaticorum and BY Draconis stars. 18: Coordinated VLA, ROSAT, and IUE observations of RS CVn binaries  

NASA Technical Reports Server (NTRS)

As part of a coordinated program of multi-wavelength observations of RS CVn close binary systems, we observed 15 systems with the Very Large Array (VLA) and 10 systems with IUE, simultaneously or nearly simultaneously with the ROSAT All Sky Survey observations of these stars. Of the 22 systems observed with ROSAT, three were observed both by IUE and the VLA. Radio observations were made at 3.6, 6 and 20 cm. Of the 15 observed RS CVn systems, we detected 11 with greater than 4 sigma confidence at one or more wavelengths. The IUE observations were made within the RIASS (ROSAT-IUE All Sky Survey) program. We present the results of the VLA observations, along with the corresponding subsets of the ROSAT Position Sensitive Proportional Counter (PSPC) X-ray and Wide Field Camera (WFC) XUV survey, and RIASS IUE observations. We obtained an extended VLA/IUE/ROSAT simultaneous coverage of one system, TY Pyx, covering more than one orbital period. These observations reveal that the quiescent radio flux of TY Pyx is relatively constant over time scales of up to 7 hours, but that it did change by a factor of 3 over 24 hours, probably due to a flare on 1990 Nov. 12. The UV, XUV and X-ray fluxes do not show large day-to-day or phase-related variability. The observation of the decay phase of a radio flare on EI Eri, with no accompanying X-ray or XUV flare, suggests that the lack of a strong correlation between X-ray and radio flares previously noted for dMe flare stars holds for RS CVn systems as well. We suggest that the radio flare may have been due to a coherent emission process such as electron cyclotron emission. The simultaneous measurements presented here provide a unique test of the general correlation between radio and soft X-ray luminosities, L(sub radio) approximately L(sub x exp m) (Drake et al. 1989) with a power-law slope close to unity, which was previously derived using data obtained years apart. Our derived slopes are consistent with and thus support the general correlations between coronal and chromospheric/transition region emissions previously derived from nonsimultaneous measurements of a much larger sample of these variable sources. However, the importance of simultaneous measurements for accurate energy balance calculations is stressed.

Fox, David C.; Linsky, Jeffrey L.; Veale, Anthony; Dempsey, Robert C.; Brown, Alex; Neff, James E.; Pagano, Isabella; Rodono, Marcello; Bromage, Gordon E.; Kuerster, Martin

1994-01-01

20

Rotational modulation and flares on RS Canum Venaticorum and BY Draconis stars. 18: Coordinated VLA, ROSAT, and IUE observations of RS CVn binaries  

NASA Astrophysics Data System (ADS)

As part of a coordinated program of multi-wavelength observations of RS CVn close binary systems, we observed 15 systems with the Very Large Array (VLA) and 10 systems with IUE, simultaneously or nearly simultaneously with the ROSAT All Sky Survey observations of these stars. Of the 22 systems observed with ROSAT, three were observed both by IUE and the VLA. Radio observations were made at 3.6, 6 and 20 cm. Of the 15 observed RS CVn systems, we detected 11 with greater than 4 sigma confidence at one or more wavelengths. The IUE observations were made within the RIASS (ROSAT-IUE All Sky Survey) program. We present the results of the VLA observations, along with the corresponding subsets of the ROSAT Position Sensitive Proportional Counter (PSPC) X-ray and Wide Field Camera (WFC) XUV survey, and RIASS IUE observations. We obtained an extended VLA/IUE/ROSAT simultaneous coverage of one system, TY Pyx, covering more than one orbital period. These observations reveal that the quiescent radio flux of TY Pyx is relatively constant over time scales of up to 7 hours, but that it did change by a factor of 3 over 24 hours, probably due to a flare on 1990 Nov. 12. The UV, XUV and X-ray fluxes do not show large day-to-day or phase-related variability. The observation of the decay phase of a radio flare on EI Eri, with no accompanying X-ray or XUV flare, suggests that the lack of a strong correlation between X-ray and radio flares previously noted for dMe flare stars holds for RS CVn systems as well. We suggest that the radio flare may have been due to a coherent emission process such as electron cyclotron emission. The simultaneous measurements presented here provide a unique test of the general correlation between radio and soft X-ray luminosities, Lradio approximately Lx exp m (Drake et al. 1989) with a power-law slope close to unity, which was previously derived using data obtained years apart. Our derived slopes are consistent with and thus support the general correlations between coronal and chromospheric/transition region emissions previously derived from nonsimultaneous measurements of a much larger sample of these variable sources. However, the importance of simultaneous measurements for accurate energy balance calculations is stressed.

Fox, D. C.; Linsky, J. L.; Veale, A.; Dempsey, R. C.; Brown, A.; Neff, J. E.; Pagano, I.; Rodono, M.; Bromage, G. E.; Kuerster, M.; Schmitt, J. H. M. M.

1994-04-01

21

QY Cas und EF Cnc - zwei besondere RRc-Sterne  

NASA Astrophysics Data System (ADS)

CCD observations of QY Cas (RA = 23:59:05.15, DE = +54:01:00.70) and EF Cnc (RA = 08:40:38.82, DE = 23:15:50.3) were obtained at my private observatory. For QY Cas 9 maxima were gained showing a light curve that varies from epoch to epoch, showing either one broad maximum or double-maxima. Revised elements are given as: QY Cas, Max = 2455887.368 + 0.2741261 *E. For EF Cnc 6 maxima were observed over a time span of 4 years. This long time helped to revise its period to: EF Cnc Max = 2456001.4818 + 0.295778 *E. For several RRc stars having a broad maximum or double-maxima the width of the bright light is found to be about 1/7 of their period.

Maintz, Gisela

2013-02-01

22

Multiple wavelength microwave observations of the RS Canum Venaticorum stars UX Arietis, HR 1099, HR 5110, and II Pegasi  

NASA Technical Reports Server (NTRS)

The variabilities, core size and magnetic field of the RS CVn star UX Arietis was measured with the VLA at pairs of frequencies near 1415 MHz and 4835 MHz on June 10, 1985. Data were also gathered on HR 1099, HR 5110 and II Peg. UX Arietis exhibited variability on time scales ranging from 30 sec to 1 hr at 4835 MHz, but no detectable variations at 1415 MHz. An upper limit of 900 billion cm was placed on the size of the core emitting region, which is estimated to have a magnetic field strength of 15 G. The 30 sec variations are attributed to absorption by thermal plasma between the G5 and K1 companions of the UX Arietis system.

Willson, Robert F.; Lang, Kenneth R.

1987-01-01

23

Rossiter-McLaughlin Observations of 55 Cnc e  

NASA Astrophysics Data System (ADS)

We present Rossiter-McLaughlin observations of the transiting super-Earth 55 Cnc e collected during six transit events between 2012 January and 2013 November with HARPS and HARPS-N. We detect no radial velocity signal above 35 cm s-1 (3?) and confine the stellar v sin i sstarf to 0.2 ± 0.5 km s-1. The star appears to be a very slow rotator, producing a very low amplitude Rossiter-McLaughlin effect. Given such a low amplitude, the Rossiter-McLaughlin effect of 55 Cnc e is undetected in our data, and any spin-orbit angle of the system remains possible. We also performed Doppler tomography and reach a similar conclusion. Our results offer a glimpse of the capacity of future instrumentation to study low amplitude Rossiter-McLaughlin effects produced by super-Earths.

López-Morales, Mercedes; Triaud, Amaury H. M. J.; Rodler, Florian; Dumusque, Xavier; Buchhave, Lars A.; Harutyunyan, Avet; Hoyer, Sergio; Alonso, Roi; Gillon, Michaël; Kaib, Nathan A.; Latham, David. W.; Lovis, Christophe; Pepe, Francesco; Queloz, Didier; Raymond, Sean N.; Ségransan, Damien; Waldmann, Ingo P.; Udry, Stéphane

2014-09-01

24

Rossiter-McLaughlin Observations of 55 Cnc e  

E-print Network

We present Rossiter-McLaughlin observations of the transiting super-Earth 55 Cnc e collected during six transit events between January 2012 and November 2013 with HARPS and HARPS-N. We detect no radial-velocity signal above 35 cm/s (3-sigma) and confine the stellar v sin i to 0.2 +/- 0.5 km/s. The star appears to be a very slow rotator, producing a very low amplitude Rossiter-McLaughlin effect. Given such a low amplitude, the Rossiter-McLaughlin effect of 55 Cnc e is undetected in our data, and any spin-orbit angle of the system remains possible. We also performed Doppler tomography and reach a similar conclusion. Our results offer a glimpse of the capacity of future instrumentation to study low amplitude Rossiter-McLaughlin effects produced by super-Earths.

Lopez-Morales, Mercedes; Rodler, Florian; Dumusque, Xavier; Buchhave, Lars A; Harutyunyan, A; Hoyer, Sergio; Alonso, Roi; Gillon, Michael; Kaib, Nathan A; Latham, David W; Lovis, Christophe; Pepe, Francesco; Queloz, Didier; Raymond, Sean N; Segransan, Damien; Waldmann, Ingo P; Udry, Stephane

2014-01-01

25

Rotational modulation and flares on RS Canum Venaticorum and BY Draconis stars. XI - Ultraviolet spectral images of AR Lacertae in September 1985  

NASA Astrophysics Data System (ADS)

High-resolution IUE SWP and LWP spectra of the bright eclipsing RS CVn system AR Lac, obtained during 40 h of continuous observations on September 18-19, 1985, are compiled and used to derive chromosphere images. The data and results are presented graphically and discussed in detail. The K 0 IV star is found to have a globally brighter trailing hemisphere and at least three distinct plage regions; the G 2 IV star has a flaring region with significant redshift and line-emission broadening and exhibits factor-of-3 variability in total emission, attributed to the presence of a large chromospherically inactive region.

Neff, J. E.; Walter, F. M.; Rodono, M.; Linsky, J. L.

1989-05-01

26

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

27

The photosphere and chromosphere of the RS Canum Venaticorum star, II Pegasi. II. A multi-wavelength campaign in August/September 1992  

NASA Astrophysics Data System (ADS)

We describe multi-wavelength, simultaneous observations of the RS CVn star, II Pegasi, most of which were obtained during the first three weeks of September 1992. These observations were made using optical and infra-red broad-band photometry, ultraviolet and optical spectroscopy and microwave monitoring. We have detected photospheric spots and chromospheric flares, as well as deriving a description of mean conditions in the quiet chromosphere. One of the flares, observed in optical photometry and ultraviolet spectroscopy is one of the most energetic ever observed on this star. We demonstrate that in its ``quiescent'' state II Peg is continually variable in most of its chromospheric emissions, as well as in its coronal output.

Byrne, P. B.; Abdul Aziz, H.; Amado, P. J.; Arevalo, M. J.; Avgoloupis, S.; Doyle, J. G.; Eibe, M. T.; Elliott, K. H.; Jeffries, R. D.; Lanzafame, A. C.; Lazaro, C.; Murphy, H. M.; Neff, J. E.; Panov, K. P.; Sarro, L. M.; Seiradakis, J. H.; Spencer, R. E.

1998-02-01

28

Long-Term Study of the Starspot Activity on the Eclipsing Short-Period RS Canum Venaticorum Star UV Piscium  

NASA Astrophysics Data System (ADS)

We present optical photometry of the short period eclipsing RS CVn system, UV Piscium for the years 1966-1984. After removing the spot effects from the light curves of Vivekananda Rao and Sarma (1981), we analyzed the cleaned data to obtain system parameters. For each light curve, we model the distortion waves in order to study the behaviour of starspots in this system.

Vivekananda Rao, P.; Radhika, P.

29

MULTIBAND PHOTOMETRIC AND SPECTROSCOPIC ANALYSIS OF HV Cnc  

SciTech Connect

In this paper, radial velocity and VI- and JHK{sub S} - (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 JHK{sub S} 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 {sub ?}, 0.52 M {sub ?}, 1.87 R {sub ?}, and 0.48 R {sub ?}, respectively. All results are compared with previously published literature values and discussed.

Gökay, G.; Gürol, B.; Derman, E., E-mail: ggokay@science.ankara.edu.tr [Astronomy and Space Sciences Department, Faculty of Science, Ankara University, 06100 Tando?an, Ankara (Turkey)

2013-11-01

30

PROMOTING A VIRTUAL TRAINING ENVIRONMENT FOR CNC Faruk nsaar  

E-print Network

. Therefore, CNC training is not restricted only in vocational training centres but also it is being taught at setting the standard CNC virtual learning in vocational training systems [4]. 2. PREPARATION OF THE CNCPROMOTING A VIRTUAL TRAINING ENVIRONMENT FOR CNC MACHINING Faruk �nsaçar Mechanical Department

Aristomenis, Antoniadis

31

Photometry of southern stars. I - The W UMa binary SX Corvi and the RS CVn binary HD 155555  

NASA Astrophysics Data System (ADS)

Photoelectric photometry of the W UMa binary SX Corvi and of the RS CVn binary HD 155555 is presented. For SX Crv we confirm the existence of photometric changes in the light curve on consecutive nights as already observed by Sanwal et al. (1974). The variations are particularly evident during minima. A new determination of the period is performed, though there are problems with the nearly equal depths of primary and secondary minima and with the long time interval between the available epochs. For HD155555 we present for the firsttime an almost complete light curve, confirming its suspectedvariability. The light curve shape resembles that seen in other RS CVnbinaries; moreover, there are non-repetitive variations probably dueto intrinsic cycle-to-cycle changes in the system.

Scaltriti, F.; Busso, M.

1984-06-01

32

Planetpol polarimetry of the exoplanet systems 55Cnc and ?Boo  

NASA Astrophysics Data System (ADS)

We present very sensitive polarimetry of 55Cnc and ?Boo in an attempt to detect the partially polarized reflected light from the planets orbiting these two stars. 55Cnc is orbited by a hot Neptune planet (55Cnce) at 0.038au, a hot Jupiter planet (55Cncb) at 0.11au and at least three more distant planets. The polarization of this system is very stable, showing no sign of the periodic variations that would be expected if a short-period planet were detected. The measured standard deviation of the nightly averaged Stokes Q/I and U/I parameters is 2.2 × 10-6. We derive upper limits on the geometric albedo, AG, and planetary radius using Monte Carlo multiple scattering simulations of a simple model atmosphere. We assume Rayleigh-like scattering and polarization behaviour (scaled by the maximum polarization, pm, at 90°) and pressure insensitive extinction. Atmospheres in which multiple scattering plays only a small role have an almost linear relation between polarization and AG. In this case, the 4? upper limit is AG < 0.13(R/1.2RJup)-2p-1m for 55Cnce. This is most easily explained if 55Cnce is relatively small, like GJ436b, and therefore not a pure H-He planet. The data do not provide a useful upper limit for 55Cncb. ?Boo is orbited by an unusually massive hot Jupiter planet. The data show a standard deviation in the night-to-night average Stokes Q/I and U/I polarization parameters of 5.1 × 10-6. The 4? upper limit is AG < 0.37(R/1.2RJup)-2p-1m for ?Boob, adopting the fairly well established orbital inclination i ~ 40°. This extends the similar upper limits reported previously for this planet to longer wavelengths. The fact that the ?Boo data show more scatter, despite the smaller photon noise for this bright star, may be due to the spot activity detected photometrically by the Microvariability & Oscillations of Stars (MOST) satellite. These results contrast markedly with the recent claim of a 3? detection of a periodic polarization signal from HD189733 with amplitude P = 2 × 10-4, attributed to the planet HD189733b. Based on observations made with the William Herschel Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatory del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. E-mail: p.w.lucas@herts.ac.uk

Lucas, P. W.; Hough, J. H.; Bailey, J. A.; Tamura, M.; Hirst, E.; Harrison, D.

2009-02-01

33

On the Interpretation of the Ultraviolet Spectra of Symbiotic Stars and Recurrent Novae. II. The 1985 Outburst of RS Ophiuchi  

NASA Astrophysics Data System (ADS)

We discuss the 1985 outburst of the symbiotic recurrent nova RS Oph using spectra obtained with the International Ultraviolet Explorer satellite and contemporaneous ground-based optical spectra. The low- resolution integrated fluxes show that a short-lived constant bolometric luminosity phase existed in the early outburst. If this reached the Eddington luminosity, it implies a minimum mass for the white dwarf of 1.2 Msun. This and the lack of evidence for eclipses in ultraviolet low-resolution spectra obtained in quiescence support the orbital solution of Dobrzycka & Kenyon (1994), in particular the low inclination of the system and the low mass, 0.5 Msun, of the red giant. The high-resolution optical and ultraviolet line profiles showed the development of two separate contributors. One was a broad-line component produced by emission from the high- velocity ejecta. The other was a narrow-line component produced in the portion of the red giant wind that was ionized by the UV pulse from the explosion and by radiation from the shock produced by the passage of the ejecta through the wind. The expanding Strömgren sphere had two effects. The strength of the line absorption from the overlying wind decreased against the ejecta and the ionized emitting gas, and the emission measure increased within the expanding H II region. We model these effects using the techniques developed in Shore & Aufdenberg (1993) to show how the column density of the cool material decreased with time. We show that the increased ionization of the wind accounts for changes in the absorption line components in the ultraviolet and use this decrease and the narrow emission-line ratios to determine the physical parameters for the line-forming region in the wind. From this, we derive the mass-loss rate for the red giant. In addition, we find evidence for a nitrogen overabundance in the wind using the time development of the N V 1240 Å doublet. The primary source for ionizing the red giant wind was radiation produced by the shocked ejecta as they traversed the stellar wind. The shock-generated emission also produced and powered the coronal species until about 100 days after outburst at which time shock breakout occurred. The ionized wind subsequently recombined, although a hot source was still present on the white dwarf on the basis of continued visibility of the ultraviolet O III fluorescence lines and the IR He I 1.08 microns line. Finally, we discuss how many of the techniques developed in this study of a photoionizing pulse propagating into a dense environment can be applied to the analysis of active galactic nuclei.

Shore, Steven N.; Kenyon, Scott J.; Starrfield, Sumner; Sonneborn, G.

1996-01-01

34

PC Versus CNC-Which Do You Choose?  

Microsoft Academic Search

Recent advances in programmable controller technology, particularly in the area of motion control, have redefined the distinctions between programmable controllers (PC's) and computer numerical controls (CNC's). Advanced PC's now offer new features, such as coordinated motion control of multiple axes. The benefits of new PC's that make them the preferred choice over CNC's in many machine control applications are discussed.

Lee E. Schmitt

1984-01-01

35

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

36

The multi-scale environment of RS Cancri from CO and H I observations  

NASA Astrophysics Data System (ADS)

We present a detailed study of the circumstellar gas distribution and kinematics of the semi-regular variable star RS Cnc on spatial scales ranging from ~1'' (~150 AU) to ~6' (~0.25 pc). Our study utilizes new CO1-0 data from the Plateau de Bure Interferometer and new H i 21 cm line observations from the Jansky Very Large Array (JVLA), in combination with previous observations. New modeling of CO1-0 and CO2-1 imaging observations leads to a revised characterization of RS Cnc's previously identified axisymmetric molecular outflow. Rather than a simple disk-outflow picture, we find that a gradient in velocity as a function of latitude is needed to fit the spatially resolved spectra, and in our preferred model, the density and the velocity vary smoothly from the equatorial plane to the polar axis. In terms of density, the source appears quasi-spherical, whereas in terms of velocity the source is axisymmetric with a low expansion velocity in the equatorial plane and faster outflows in the polar directions. The flux of matter is also larger in the polar directions than in the equatorial plane. An implication of our model is that the stellar wind is still accelerated at radii larger than a few hundred AU, well beyond the radius where the terminal velocity is thought to be reached in an asymptotic giant branch star. The JVLA H i data show the previously detected head-tail morphology, and also supply additional details about the atomic gas distribution and kinematics. We confirm that the head seen in H i is elongated in a direction consistent with the polar axis of the molecular outflow, suggesting that we are tracing an extension of the molecular outflow well beyond the molecular dissociation radius (up to ~0.05 pc). The 6'-long H i tail is oriented at a PA of 305°, consistent with the space motion of the star. The tail is resolved into several clumps that may result from hydrodynamic effects linked to the interaction with the local interstellar medium. We measure a total mass of atomic hydrogen MHI ? 0.0055 M? and estimate a lower limit to the timescale for the formation of the tail to be ~6.4 × 104 years. Based on observations carried out with the IRAM Plateau de Bure Interferometer and the IRAM 30 m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).

Hoai, D. T.; Matthews, L. D.; Winters, J. M.; Nhung, P. T.; Gérard, E.; Libert, Y.; Le Bertre, T.

2014-05-01

37

A hybrid type small 5-axis CNC milling machine  

E-print Network

5-axis CNC milling machines are important in a number of industries ranging from aerospace to consumer-die-mold machining because they can deliver high machining accuracy with a spindle tilting capacity. Most of these ...

Son, Seung-Kil, 1964-

2002-01-01

38

Characterising the atmosphere of the super-Earth 55Cnc e  

NASA Astrophysics Data System (ADS)

So-called "super-Earth" planets could come in a variety of flavors, but to date we have few observational constraints on their diversity. In fact, atmospheres of only two members of the class have been measured in transmission so far. Here we propose to observe two transits of the third of that class that can be characterised, the super-Earth 55Cnc e, orbiting the brightest star in the sky known to harbor a transiting planet, using WFC3 in the near-infrared. This planet's low average density implies either a significant water fraction or a hydrogen-rich envelope. However, given the intensity of its stellar insolation, a hydrogen-rich envelope is expected to have evaporated. If, on the other hand, 55Cnc e contains a large water fraction, it is expected to have a small scale-height envelope dominated by water. Our proposed observations will not only investigate its atmospheric properties and constrain the scale-height, but also demonstrate HST's capabilities for characterizing small planets around nearby, bright stars, which will be prime targets for upcoming surveys such as the TESS mission.

de Mooij, Ernst

2014-10-01

39

Searching for flickering variability in several symbiotic stars and related objects: BX Mon, V471 Per, RS Oph, V627 Cas, CI Cam V886 Her, Z And, T CrB, MWC 560, V407 Cyg  

E-print Network

UBVRI photometry observations of 10 symbiotic stars and related objects obtained in the period 2002-2003 are presented. Analysing differential light curves we found rapid light variations with timescales of tens of minutes and significant amplitudes in the well-known flickerers MWC 560, RS Oph, V407 Cyg and T CrB. MWC 560 and V407 Cyg demonstrate quasi periodic oscillations (QPO) with similar amplitudes and timescales. Flickering and unusual flare in V627 Cas as well as some indications of flickering presence in BX Mon are detected. The existence of 29 minutes oscillations in Z And with an amplitude about 0.02 mag in U band is confirmed. Only one symbiotic star, V471 Per, and both non symbiotic, CI Cam and V886 Her seem to be constant on flickering timescales. Nevertheless, small night to night changes in the brightness of V886 Her were observed as well.

M. Gromadzki; M. Mikolajewski; T. Tomov; I. Bellas-Velidis; A. Dapergolas; C. Galan

2006-04-05

40

Vega-like stars  

NASA Astrophysics Data System (ADS)

The results on Vega-like stars obtained with ISO are discussed. We find that the incidence of Vega-like disks is approximately 21% on average, with some dependency upon the spectral type. While young stars do more frequently show disks than old stars, there is no clear trend in the amount of dust seen at different ages. We also discuss the discovery of a Vega-like disk associated with ?1Cnc, a star which is know to be orbited by a planet. Finally we show preliminary results on HD 207129, an old G star with a very prominent IR excess.

Dominik, C.; Habing, H. J.; Laureijs, R. J.; Jourdain de Muizon, M.; Bouchet, P.; Heske, A.; Kessler, M. F.; Leech, K.; Metcalfe, L.; Salama, A.; Siebenmorgen, R.; Trams, N. R.

1999-03-01

41

Effect of cellulose nanocrystals (CNC) particle morphology on dispersion and rheological and mechanical properties of polypropylene/CNC nanocomposites.  

PubMed

Polypropylene (PP) nanocomposites containing spray-dried cellulose nanocrystals (CNC), freeze-dried CNC, and spray-freeze-dried CNC (CNCSFD) were prepared via melt mixing in an internal batch mixer. Polarized light, scanning electron, and atomic force microscopy showed significantly better dispersion of CNCSFD in PP/CNC nanocomposites compared with the spray-dried and freeze-dried CNCs. Rheological measurements, including linear and nonlinear viscoelastic tests, were performed on PP/CNC samples. The microscopy results were supported by small-amplitude oscillatory shear tests, which showed substantial rises in the magnitudes of key rheological parameters of PP samples containing CNCSFD. Steady-shear results revealed a strong shear thinning behavior of PP samples containing CNCSFD. Moreover, PP melts containing CNCSFD exhibited a yield stress. The magnitude of the yield stress and the degree of shear thinning behavior increased with CNCSFD concentration. It was found that CNCSFD agglomerates with a weblike structure were more effective in modifying the rheological properties. This effect was attributed to better dispersion of the agglomerates with the weblike structure. Dynamic mechanical analysis showed considerable improvement in the modulus of samples containing CNCSFD agglomerates. The percolation mechanical model with modified volume percolation threshold and filler network strength values and the Halpin-Kardos model were used to fit the experimental results. PMID:24809661

Khoshkava, Vahid; Kamal, Musa R

2014-06-11

42

Research on a Platform to Build Real-time Applications for CNC Systems  

Microsoft Academic Search

In CNC systems, real-time applications such as prototyping of control algorithms and optimizing servo parameters are needed frequently. The most widely used software tools to build such applications are proprietary and expensive. This paper aims to introduce a totally open platform to build real-time applications for CNC systems, which is implemented by applying SCILAB to CNC systems in RTAI Linux

Wei Zhang; Dong Yu; Yi Hu

2008-01-01

43

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 t) with prewhitening to determine characteristics and significance of waves with 3 periods; b) the wavelet analysis to determine characteristics of statistically significant waves; ) 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.om. 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

44

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

45

Generation of gear tooth surfaces by application of CNC machines  

NASA Technical Reports Server (NTRS)

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.

1994-01-01

46

Rotational modulation and flares on RS Canum Venaticorum and BY Draconis stars. XIX. Simultaneous IUE, ROSAT, VLA, and visual observations of TY Pyxidis.  

NASA Astrophysics Data System (ADS)

In November 1990, we observed the eclipsing binary system TY Pyxidis with the IUE satellite simultaneously with the ROSAT All-Sky Survey. The IUE and ROSAT/WFC observations covered the 3.2-day period of this system continuously, while the ROSAT/PSPC coverage was limited to 2.26days. We also observed TY Pyx with the VLA for a total of 22 hours throughout this period, and we obtained simultaneous visual photometry and spectroscopy. We compare the rotational and eclipse modulation of the ultraviolet line fluxes and line profiles with the x-ray, extreme-ultraviolet, radio, and visual-light variability. We present the multi-wavelength light curves, and we compare the high-resolution Mgiik profiles with the simultaneously obtained CaiiK profiles. Although the visual light curve suggests the presence of large photospheric spots, no rotational modulation is evident in the ultraviolet, x-ray, and radio flux. This suggests that the outer atmosphere is more uniformly covered with magnetic activity than the photosphere. The rare absence of large flux variations permits us to study an RS CVn system with large intrinsic ultraviolet, x-ray, and radio fluxes but without complications introduced by large active regions or flares. Until now, among the extensively monitored RS CVn systems, only the long-period Capella has shown such a constant radiative output.

Neff, J. E.; Pagano, I.; Rodono, M.; Brown, A.; Dempsey, R. C.; Fox, D. C.; Linsky, J. L.

1996-06-01

47

Constrained identification of virtual CNC drives using a genetic algorithm  

Microsoft Academic Search

This paper presents a genetic algorithm (GA) for identifying virtual models of machine tool drives with minimal intervention\\u000a to the production machine. The proposed solution builds on the “rapid identification” concept reported earlier in literature,\\u000a in which a short series of motion data is captured from the Computer Numerical Control (CNC) and used for closed-loop transfer\\u000a function identification subject to

Wilson Wai-Shing Wong; Kaan Erkorkmaz

2010-01-01

48

Bondage number of the discrete torus Cn×C4  

Microsoft Academic Search

The bondage number b(G) of a graph G is the cardinality of a smallest set of edges whose removal from G results in a graph with a domination number greater than the domination number of G. In this paper, we show that the bondage number of the Cartesian product Cn×C4 of two cycles Cn(n?4) and C4 is equal to 4,

Liying Kang; Moo Young Sohn; Hye Kyung Kim

2005-01-01

49

Retrofitment of a CNC machine for hybrid layered manufacturing  

Microsoft Academic Search

Subtractive manufacturing [computer numerical controlled (CNC) machining] has high quality geometric and material properties\\u000a but is slow, costly, and infeasible in some cases. On the contrary additive manufacturing (rapid prototyping) has total automation\\u000a but compromises quality. A hybrid layered manufacturing process presented in this study combines the best features of both\\u000a these approaches. It uses arc weld deposition for building

K. P. Karunakaran; S. Suryakumar; Vishal Pushpa; Sreenathbabu Akula

2009-01-01

50

Research on the thermal load of CNC milling machine  

NASA Astrophysics Data System (ADS)

Machine tool accuracy is the assurance of top-quality products in machining processes. In the all kinds of errors related to machine tools, thermal errors of machine tools' parts play an important role in machining accuracy and directly influence both the surface finish and the geometric shape of the finished workpiece. Therefore the objective of this work was to analyze the temperature field and thermal deformation in some parts of CNC machine tools. In this paper, the thermal boundary condition of main spindle and driving ball screw in CNC milling machine are discussed, some parameters in heat transfer process are calculated. Based on steady heat transfer process, the thermal analysis about spindle and ball screw is carried out under ANSYS environment, and their temperature fields are obtained when milling machine is working. Then the deformations of main spindle and ball screw are acquired by applying the thermal structure coupling element. Furthermore, in order to decrease main parts' deformations and improve the accuracy of CNC milling machine, some suggests are proposed.

Nie, Xue-Jun; Wu, Ping-Dong

2011-05-01

51

Research on the thermal load of CNC milling machine  

NASA Astrophysics Data System (ADS)

Machine tool accuracy is the assurance of top-quality products in machining processes. In the all kinds of errors related to machine tools, thermal errors of machine tools' parts play an important role in machining accuracy and directly influence both the surface finish and the geometric shape of the finished workpiece. Therefore the objective of this work was to analyze the temperature field and thermal deformation in some parts of CNC machine tools. In this paper, the thermal boundary condition of main spindle and driving ball screw in CNC milling machine are discussed, some parameters in heat transfer process are calculated. Based on steady heat transfer process, the thermal analysis about spindle and ball screw is carried out under ANSYS environment, and their temperature fields are obtained when milling machine is working. Then the deformations of main spindle and ball screw are acquired by applying the thermal structure coupling element. Furthermore, in order to decrease main parts' deformations and improve the accuracy of CNC milling machine, some suggests are proposed.

Nie, Xue-Jun; Wu, Ping-Dong

2010-12-01

52

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

53

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.

54

Study on Closed-Loop Servo Control System and Background Service Based on CNC  

Microsoft Academic Search

In order to find and treat fault or abnormal occurrences in numerically controlled machine tool of flexible manufacturing system in real-time, a study for computer numerically controlled (CNC) on-line fault diagnostics system has been carried out. The system can look up one or more sticking points of numerically controlled machine tool fault simply, locate CNC faults rapidly and accurately, but

Li Hui; Mao Jun; Li Xinhong; Xin Zhongwei

2009-01-01

55

Adjustment of CNC machine tool controller setting values by an experimental method  

Microsoft Academic Search

This paper presents an adjustment technique on controller setting values in CNC machine tools by measurement of servo induced feed drive errors. At high feed rate operations of CNC machine tools, servo induced errors are usually dominant and large compared with geometric errors. For measurement of the servo induced errors, an experimental equipment which incorporates two linear displacement sensors and

H. D. Kwon; M. Burdekin

1998-01-01

56

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

57

International Conference on E-Portfolio Process in Vocational Education-EPVET 2007 REVISITING CNC TRAINING A "VIRTUAL TRAINING CENTRE  

E-print Network

for vocational training centres for a very long time. Training on CNC should follow similar developments of their CNC operation and programming knowledge. Therefore, CNC training is not only restricted to vocational the development of a Virtual Training Centre (VTC) to promote and reinforce Vocational Training in Computer

Aristomenis, Antoniadis

58

Volumetric error identification for CNC machine tool based on multi-body system and vector diagonal measurement  

Microsoft Academic Search

To reduce the influence of the geometric error on machining precision of CNC machine, a new method based on multi-body system theory and the laser sequential step diagonal vector measurement method to distinguish the geometric errors of CNC machine tool was presented. Firstly geometric errors modeling of CNC machine tool based on multi-body system theory was established. Then laser sequential

Zhenya He; Jianzhong Fu; Xinhua Yao; Wenjie Qian

2010-01-01

59

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

60

Digital Design and Fabrication Techniques Using a 3-Axis CNC Mill  

E-print Network

of where formal, spatial, and material possibilities lie. This project focuses specifically on using CNC (Computer Numerical Control) fabrication techniques to produce three-dimensional forms with poly-urethane foam aimed at achieving certain surface...

Coffman, Ky

2010-07-14

61

Time-optimal CNC tool paths : a mathematical model of machining  

E-print Network

Free-form surface machining is a fundamental but time-consuming process in modern manufacturing. The central question we ask in this thesis is how to reduce the time that it takes for a 5-axis CNC (Computer Numerical ...

Kim, Taejung, 1969-

2001-01-01

62

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

63

Continuous tone printing in silicone from CNC milled matrices  

NASA Astrophysics Data System (ADS)

Current research at the Centre for Fine Print Research (CFPR) at the University of the West of England, Bristol, is exploring the potential of creating coloured pictorial imagery from a continuous tone relief surface. To create the printing matrices the research team have been using CNC milled images where the height of the relief image is dictated by creating a tone curve and then milling this curve into a series of relief blocks from which the image is cast in a silicone ink. A translucent image is cast from each of the colour matrices and each colour is assembled - one on top of another - resulting is a colour continuous tone print, where colour tone is created by physical depth of colour. This process is a contemporary method of continuous tone colour printing based upon the Nineteenth Century black and white printing process of Woodburytype as developed by Walter Bentley Woodbury in 1865. Woodburytype is the only true continuous tone printing process invented, and although its delicate and subtle surfaces surpassed all other printing methods at the time. The process died out in the late nineteenth century as more expedient and cost effective methods of printing prevailed. New research at CFPR builds upon previous research that combines 19th Century Photomechanical techniques with digital technology to reappraise the potential of these processes.

Hoskins, S.; McCallion, P.

2014-02-01

64

Synthesis of chemical cross-linked gelatin hydrogel reinforced with cellulose nanocrystals (CNC)  

NASA Astrophysics Data System (ADS)

A novel method was performed to obtain hydrogel with superior sensitivity towards changes in pH and temperature by incorporation of CNC into gelatin based hydrogel. Glutaraldehyde was used as cross-linker due to its high chemical reactivity towards NH2 group on gelatin. Different ratio of gelatin / CNC hydrogel was produced in order to study the effects of CNC towards the swelling behaviour of hydrogel at different pH and temperature. Swelling tests were performed at different pH range from pH 3 to pH 11. Temperature swelling tests were performed at 25 °C and 37 °C. The hydrogel showed impressive pH sensitivity and maximum swelling was obtained at pH 3. Higher swelling ratio was observed at higher temperature. SEM micrographs showed that the pore size of hydrogel decreased with increasing CNC content due to formation of more rigid hydrogel structure. The characteristics of the hydrogel to respond to different pH and temperature suggest that gelatin / CNC hydrogel are promising candidates to be developed as drug carrier.

Yin, Ooi Shok; Ahmad, Ishak; Amin, Mohd. Cairul Iqbal Mohd

2014-09-01

65

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

Federal Register 2010, 2011, 2012, 2013

...Renewal Exemption--Norfolk Southern Railway Company Under 49 CFR 1011.7(a...miles of rail line from Norfolk Southern Railway Company (NSR).\\1\\ The rail lines...According to C&NC, the interchange point with NSR is New Castle. C&NC...

2011-07-05

66

RS Ophiuchi: Connections to the Symbiotic Variable AG Dra  

Microsoft Academic Search

AG Dra is a symbiotic variable bearing a number of similarities to the suspected emitting components in RS Oph among which are an irradiated red giant mass donor, metal poor, similarly long orbital periods, a hot accreting white dwarf irradiating an optically thick bright accretion disk. Both objects have been counted among the yellow symbiotic stars (Smith et al. 1996).

E. M. Sion; J. Miko

2008-01-01

67

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

68

RECEIPTS Amount PAYMENTS Amount RS. P. RS. P.  

E-print Network

RECEIPTS Amount PAYMENTS Amount RS. P. RS. P. Opening Balance 59,971.00 Investment in Charitable Balance 317,296.00 Unit Trust of India Investments 257,825.00 Excess of income over expenditure 216 Interest 7,293.00 Audit Fees 500.00 Dividend from UTI 38,700.00 Payment to Printers for Sovenir 43

Sivalingam, Krishna M.

69

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

70

Improved precision on the radius of the nearby super-Earth 55 Cnc e  

E-print Network

We report on new transit photometry for the super-Earth 55?Cnc?e obtained with Warm Spitzer/IRAC at 4.5 ?m. An individual analysis of these new data leads to a planet radius of [superscript 2.21]+0.15 [over] -0.16 R[subscript ...

Gillon, M.

71

An optimisation approach to the contour error control of CNC machine tools using genetic algorithms  

Microsoft Academic Search

A contour control strategy has been studied in this paper to improve the contour error of CNC machine tools. First, a single axis controller is analysed and then a velocity feedforward controller is added in the velocity loop. To further reduce the contour error, a cross-coupled controller is adopted and an algorithm for an on-line estimation of the contour error

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

1997-01-01

72

Virtual Training Centre For CNC: a Sample Virtual Training Environment Mehmet Sahin1  

E-print Network

Virtual Training Centre For CNC: a Sample Virtual Training Environment Mehmet Sahin1 , Süleyman bilalis@dpem.tuc.gr Abstract It is a fact that virtual training has been a scope of interest for vocational training for a very long time. However, it needs more time to be more common in all specific

Aristomenis, Antoniadis

73

Chemical crosslinking of acrylic acid to form biocompatible pH sensitive hydrogel reinforced with cellulose nanocrystals (CNC)  

NASA Astrophysics Data System (ADS)

The purpose of this study is to produce a novel pH and temperature sensitive hydrogel, composed of poly(acrylic acid) (PAA) and cellulose nanocrystal (CNC). CNC was extracted from kenaf fiber through a series of alkali and bleaching treatments followed by acid hydrolysis. The PAA was then subjected to chemical cross-linking using the cross-linking agent (N,N-methylenebisacrylamide) with CNC entrapped in PAA matrix. The mixture was casted onto petri dish to obtain disc shape hydrogel. The effects of reaction conditions such as the ratio of PAA and CNC on the swelling behavior of the hydrogel obtained towards pH and temperature were studied. The obtained hydrogel was further subjected to different tests such swelling test for swelling behaviour at different pH and temperature along with scanning electron microscopy (SEM) for morphology analysis. The hydrogel obtained showed excellent pH sensitivity and obtained maximum swelling at pH 7. Besides that, hydrogel obtained showed significant increase in swelling ratio when temperature of swelling medium was increased from 25°C to 37°C. SEM micrograph showed that the pore size of the hydrogel decreases with increase of CNC content proving that the hydrogel structure became more rigid with addition of CNC. The PAA/CNC hydrogel with such excellent sensitivity towards pH and temperature can be developed further as drug carrier.

Lim, Lim Sze; Ahmad, Ishak; Lazim, Mohd Azwani Shah Mat; Amin, Mohd. Cairul Iqbal Mohd

2014-09-01

74

The large outbursts studied by small telescopes - the case of RS Oph  

NASA Astrophysics Data System (ADS)

Cataclysmic variables (CVs) are one of the dominant part in astronomical research. Small telescopes are widely used to search for the sudden brightening of such stars. We present our experience with observations of the RS Ophiuchi (RS Oph) and analyses of the light curves. RS Oph is a binary system with 6 recorded outbursts classified as a recurrent nova (RN). We used the telescopes of AI SAS to measure the brightness of RS Oph after its last outburst occurred on February 12, 2006. The new observations indicate the ongoing mass transfer. % and the estimation of the mass transfer rate allow to make a prediction of the %next outburst of this RN.

Kundra, E.; Hric, L.

2014-03-01

75

RECEIPTS Amount PAYMENTS Amount RS. P. RS. P.  

E-print Network

RECEIPTS Amount PAYMENTS Amount RS. P. RS. P. Opening Balance 15,762.00 Investment in Charitable. Opening Balance 94,012.00 Unit Trust of India Investments 257,825.00 Excess of income over expenditure 223.00 Bank Interest 1,440.00 Audit Fees 500.00 Dividend from UTI 12,600.00 Closing Balance 59,971.00 239

Sivalingam, Krishna M.

76

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

77

The vibration behavior of impeller blades in the five-axis CNC flank milling process  

Microsoft Academic Search

Today, in most cases, impellers of centrifugal compressors are produced by flank milling on five-axis CNC milling machines.\\u000a The complex three-dimensional geometry of the very thin blades consists of ruled surfaces. The flank milling process allows\\u000a a fast production of the impellers and the surface of the blades is of high quality. The limited strength of the very thin\\u000a blades

Kawin Sonthipermpoon; E. Bohez; H. Hasemann; M. Rautenberg

2010-01-01

78

High-accuracy path-tracking by multi-axis coordination in CNC machines  

Microsoft Academic Search

A multi-axis coordinated control (MACC) system has been developed to achieve high-speed, high accuracy path-tracking in computerized numerically controlled (CNC) machines. Sharp changes in path speed or direction are kept within permitted acceleration levels by means of input command smoothing, which is achieved through the use of multi-axis coordination and a time-scaling method based on previewed velocity information. Since MACC

K. Aoki; N. Iwazawa; T. Tsujisawa; U. Sakaguchi; E. Nakawatase

1994-01-01

79

Form design of CNC machine tools using SVM-Kansei engineering model  

Microsoft Academic Search

In the past, the design of CNC machine tools focused on their functional aspects and was hard to acquire any resonance with customers. Nowadays, despite the needs of low-price and high-quality machine, more and more customers request a good-looking machine. Regarding this, our study aims to provide a novel approach based on the combination of Kansei engineering and support vector

Kun-Chieh Wang; Jung-Chin Liang; Yu-Cai Lin

2008-01-01

80

Implementing an industrial product-service system for CNC machine tool  

Microsoft Academic Search

This paper presents the concept of an industrial product-service system for CNC machine tool (mt-iPSS) based on the provision\\u000a and enhancement of machining capabilities. An architecture is proposed to enable the mt-iPSS from the aspects of both hardware\\u000a and software. The hardware aspect includes a combination of a machine tool and its attachments. The software aspects include\\u000a four layers. They

Q. Q. Zhu; P. Y. Jiang; G. Q. Huang; T. Qu

2011-01-01

81

Rotational modulation and flares on RS CVn and BY Dra-type stars. I - Photometry and spot models for BY Dra, AU Mic, AR Lac, II Peg and V 711 Tau (= HR 1099)  

NASA Technical Reports Server (NTRS)

Multicolor wide-band photometry of five active stars is presented. The observations were carried out at several places before, during and after the period of IUE observations for the purpose of determining the location, sizes, and evolution of photospheric spots at the time when chromospheric, transition region, and coronal activity data were obtained from UV and radio observations. II Peg, BY Dra, and AU Mic show fairly stable quasi-sinusoidal light curves, while AR Lac and V 711 Tau show double-peaked light curves. For V 711 Tau, a remarkable evolution of the spotted area extent and/or longitude distribution is found. Small, but definite color variations that are consistent with the cool spot hypothesis have also been detected for BY Dra, II Peg and V 711 Tau.

Rodono, M.; Cutispoto, G.; Pazzani, V.; Catalano, S.; Byrne, P. B.

1986-01-01

82

R-S model and radio binary pulsars  

NASA Astrophysics Data System (ADS)

The R-S model of pulsar emission (Ruderman and Sutherland, 1975) is extended and applied to the case of binary pulsars. It is shown that the 1-TV potential difference across the magnetospheric gap and the outward-directed electric field required by the R-S model for the generation of radio waves will be negated if the number density of matter at the Alfven surface is greater than 7.2 x 10 to the 7th/cu cm, a condition satisfied by most binary systems containing neutron stars, where there is significant stellar wind or Roche-lobe overflow from the companion star. Only in the relatively rare case of a compact companion can the gap be maintained and pulsar emission be generated; this is exactly the case for two of the three observed binary pulsars (PSR 1913 + 16 and PSR 0655 + 64). It is concluded that the R-S model offers a sufficient explanation for the rare occurrence of binary pulsars.

Wang, Z.

83

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

84

Visualization of the Drosophila dKeap1-CncC interaction on chromatin illumines cooperative, xenobiotic-specific gene activation.  

PubMed

Interactions among transcription factors control their physiological functions by regulating their binding specificities and transcriptional activities. We implement a strategy to visualize directly the genomic loci that are bound by multi-protein complexes in single cells in Drosophila. This method is based on bimolecular fluorescence complementation (BiFC) analysis of protein interactions on polytene chromosomes. Drosophila Keap1 (dKeap1)-CncC complexes localized to the nucleus and bound chromatin loci that were not bound preferentially by dKeap1 or CncC when they were expressed separately. dKeap1 and CncC binding at these loci was enhanced by phenobarbital, but not by tert-butylhydroquinone (tBHQ) or paraquat. Endogenous dKeap1 and CncC activated transcription of the Jheh (Jheh1, Jheh2, Jheh3) and dKeap1 genes at these loci, whereas CncC alone activated other xenobiotic response genes. Ectopic dKeap1 expression increased CncC binding at the Jheh and dKeap1 gene loci and activated their transcription, whereas dKeap1 inhibited CncC binding at other xenobiotic response gene loci and suppressed their transcription. The combinatorial chromatin-binding specificities and transcriptional activities of dKeap1-CncC complexes mediated the selective activation of different sets of genes by different xenobiotic compounds, in part through feed-forward activation of dKeap1 transcription. PMID:25063457

Deng, Huai; Kerppola, Tom K

2014-08-01

85

Changes of a mean yearly brightness on 11 dKe-dMe stars  

NASA Astrophysics Data System (ADS)

Photometric behaviour of 11 dKe-dMe stars have been studied in a range of some decades using the Sternberg Astronomical Institute plate collection. The yearly mean light variations up to several tenths magnitudes were determined or suspected for stars V1816 Cyg, V775 Her, V808 TAu, EI Cnc. Time scales of such variations are estimated of 4 - 50 years. The star V910 Ori is a variable too, but its light curve is not a typical for BY Dra stars.

Bondar', N. I.

2001-06-01

86

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

87

Placement of the material temperature sensor during measuring the accuracy of CNC machine tools  

NASA Astrophysics Data System (ADS)

In view of the dispute on the placement of material sensor when measuring the positional accuracy of a linear axis of a CNC machine tool, this paper presents the method and principle of deciding where to put the material temperature sensor. The positional accuracy of the linear axis of the machine tool is one of the most important performance parameters, and it must be measured when setup and check. The placement of the material temperature sensor has great influence on the measurement accuracy. At present, there are two main views on this issue: one is to place the sensor on the table of the machine tool, the other is to place it on the feedback system. This conflict between these two debates often makes the measurers feel confused and as a result influences the measure quality, sometimes. This thesis attempts to classify the CNC machine tools positional accuracy measurement according to its different purposes, then further presents the best placement. The thesis also elaborates other relevant questions of the placement of the material temperature sensor.

Zhao, Dong-sheng; Jia, Min-qiang; Zhang, Jian; Sun, Lei; Li, Wei-jun

2013-10-01

88

The Neural-fuzzy Thermal Error Compensation Controller on CNC Machining Center  

NASA Astrophysics Data System (ADS)

The geometric errors and structural thermal deformation are factors that influence the machining accuracy of Computer Numerical Control (CNC) machining center. Therefore, researchers pay attention to thermal error compensation technologies on CNC machine tools. Some real-time error compensation techniques have been successfully demonstrated in both laboratories and industrial sites. The compensation results still need to be enhanced. In this research, the neural-fuzzy theory has been conducted to derive a thermal prediction model. An IC-type thermometer has been used to detect the heat sources temperature variation. The thermal drifts are online measured by a touch-triggered probe with a standard bar. A thermal prediction model is then derived by neural-fuzzy theory based on the temperature variation and the thermal drifts. A Graphic User Interface (GUI) system is also built to conduct the user friendly operation interface with Insprise C++ Builder. The experimental results show that the thermal prediction model developed by neural-fuzzy theory methodology can improve machining accuracy from 80µm to 3µm. Comparison with the multi-variable linear regression analysis the compensation accuracy is increased from ±10µm to ±3µm.

Tseng, Pai-Chung; Chen, Shen-Len

89

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

90

AT Cnc: A Second Dwarf Nova with a Classical Nova Shell  

NASA Astrophysics Data System (ADS)

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 ~5 × 10-5 M ?, typical of classical novae.

Shara, Michael M.; Mizusawa, Trisha; Wehinger, Peter; Zurek, David; Martin, Christopher D.; Neill, James D.; Forster, Karl; Seibert, Mark

2012-10-01

91

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

92

Associations between rs965513/rs944289 and papillary thyroid carcinoma risk: a meta-analysis.  

PubMed

Single-nucleotide polymorphisms of rs965513 (9q22.33) and rs944289 (14q13.3) may be involved in the pathogenesis of papillary thyroid carcinoma (PTC). But, relevant genetic studies reported different results. The aim of this meta-analysis was to derive a more precise assessment of the association of rs965513/rs944289 polymorphism with PTC risk. Relevant studies were identified using PubMed, ISI Web of knowledge, Medline, Embase, Google Scholar Search database, SinoMed (Chinese), CNKI (Chinese), GeNii (Japanese) and ICHUSHI (Japanese) (update to December, 2013). A total of eight case-control studies with 52,363 subjects for rs965513 and 51,120 subjects for rs944289 were included. The results showed significant associations of rs965513/rs944289 with PTC risk existed in overall population (for rs965513, A vs. G: OR 1.71 (1.56-1.86); for rs944289, T vs. C: OR 1.29 (1.23-1.37)). Subgroup analysis by ethnicity showed that there were significant associations in Asians (for rs965513, A vs. G: OR 1.48 (1.27-1.73); for rs944289, T vs. C: OR 1.35 (1.18-1.55)), in Europeans (for rs965513, A vs. G: OR 1.74 (1.61-1.88); for rs944289, T vs. C: OR 1.24 (1.14-1.34)), and in Americans (for rs965513, A vs. G: OR 2.00 (1.76-2.27); for rs944289, T vs. C: OR 1.29 (1.14-1.47)). In conclusion, Rs965513 [A] and rs944289 [T] are risk factors of PTC. Effect estimate for rs965513 polymorphism is higher in Americans than in Asians. PMID:24723258

Ai, Lizhe; Liu, Xiaoli; Yao, Yuhang; Yu, Yaqin; Sun, Hui; Yu, Qiong

2014-11-01

93

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

94

The X-ray spectra and the rotation-activity connection of RS CVN binaries  

NASA Technical Reports Server (NTRS)

Results from a survey of RS CVn binaries which were observed with the Imaging Proportional Counter (IPC) on board the Einstein Observatory are presented. Spectral analyses of the IPC pulse height spectra show that the coronae of RS CVn binaries always contain hot gas with temperatures 10 million K, similar to active late-type main sequence stars, and that at least 2 temperature components are necessary to account for the higher quality IPC spectra (when absorption is unimportant). It is argued that these bimodal temperature distributions indicate true distributions of emission measure vs temperature that are continuous (just as is the case for magnetically-confined coronal plasma loops observed on the Sun). It is shown that none of the derivable X-ray characteristics of RS CVn binaries depend on rotation period, implying that claims of period-activity relationships in RS CVn binaries are unfounded.

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

1985-01-01

95

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

NASA Technical Reports Server (NTRS)

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.

1982-01-01

96

Study on grinding of free-form optics surface in three-axis CNC machine  

NASA Astrophysics Data System (ADS)

Due to the glass is a type of brittle material, so the high-precision free-form optics of glass material is usually machined by the technical of grinding. In this paper, for the characteristics of the diamond grinding wheel, analyzing the grinding path of free-form optics and mathematical model of the path is established based on the three-axis CNC grinding device. Moreover, the cause of the interference in the process of grinding is analyzed and the methods of avoiding. Finally, based on the above analysis results, through the experiment, the free-form optics surface accuracy was reached to 3.6um, realize the machining of the free-form optics.

Yang, Haicheng; Zhang, Yun-long; Zhang, Feng; Wang, Zhibin; Bao, Long-xiang; Su, Ying; Guo, Rui; Liu, Xuan-min

2014-08-01

97

IUE spectra of a flare in the RS Canum Venaticorum-type system UX Arietis  

NASA Technical Reports Server (NTRS)

IUE spectra of UX Ari obtained during the large flare of 1979 January 1 exhibit chromospheric and transition-region emission-line fluxes about 2.5 and 5.5 times brighter than quiescent fluxes, respectively, and up to 1400 times brighter than the quiet sun. A high-dispersion spectrum of the 2000-3000 A region exhibits enhanced Fe II emission, which is probably associated mainly with the K0 IV star, and enhanced Mg II emission with asymmetric wings extending to +475 km/s. These line wings are interpreted as evidence for mass flow from the K0 IV star to the G5 V star. A speculative scenario of major long-lived RS CVn flares is proposed in which the component stars have very large corotating flux tubes, which occasionally interact. Magnetic reconnection results in flux tubes that temporarily connect the two stars.

Simon, T.; Linsky, J. L.; Schiffer, F. H., III

1980-01-01

98

Tidal Dissipation and Eccentricity Pumping: Implications for the Depth of the Secondary Eclipse of 55 Cnc e  

NASA Astrophysics Data System (ADS)

We use the super-Earth 55 Cnc e (Fischer et al. 2008) as a case-study to address an observable effect of tidal heating. This transiting short-period planet belongs to a compact multiple system with massive planets. We investigate whether planet-planet interactions can force the eccentricity of this planet to a level that would affect the eclipse depth observed with Spitzer.

Bolmont, E.; Selsis, F.; Raymond, S. N.; Leconte, J.; Hersant, F.; Maurin, A.-S.; Pericaud, J.

2014-01-01

99

Search for RS-gravitons at CDF  

SciTech Connect

We present a search for Randall-Sundrum (RS) gravitons decaying to diphotons or dielectrons or dimuons, performed with the CDF II detector and using up to 5.7 fb{sup -1} of integrated luminosity. The respective mass spectra are consistent with the ones expected by the standard model. For the RS-model parameter k/{bar M}{sub Pl} = 0.1, RS-gravitons with mass less than 1111 GeV/c{sup 2} are excluded at 95% CL.

Strologas, John; /New Mexico U.

2011-09-01

100

RS Microwave Company, Inc.RS Microwave Company, Inc. 2/23/052/23/05 DESIGNING FILTERS TO WITHSTAND  

E-print Network

RS Microwave Company, Inc.RS Microwave Company, Inc. 2/23/052/23/05 DESIGNING FILTERS TO WITHSTAND INIMICAL ENVIRONMENTS By R. V. SNYDER RS MICROWAVE BUTLER, NJ IMS 2005 Workshop WMB Filters II Practical Aspects of Microwave Filter Design and Realization #12;RS Microwave Company, Inc.RS Microwave Company, Inc

Yu, Ming

101

Direct Observation of the Fourth Star in the Zeta Cancri System  

E-print Network

Direct imaging of the zeta Cnc system has resolved the fourth star in the system, which is in orbit around zeta Cnc C. The presence of the fourth star has been inferred for many years from irregularities in the motion of star C, and recently from C's spectroscopic orbit. However, its mass is close to that of C, making its non-detection puzzling. Observing at wavelengths of 1.2, 1.7, and 2.2 microns with the adaptive-optics system of the CFHT, we have obtained images which very clearly reveal star D and show it to have the color of an M2 star. Its brightness is consonant with its being two M stars, which are not resolved in our observations but are likely to be in a short-period orbit, thereby accounting for the large mass and the difficulty of detection at optical wavelengths, where the magnitude difference is much larger. The positions and colors of all four stars in the system are reported and are consistent with the most recent astrometric observations.

J. B. Hutchings; R. F. Griffin; F. Menard

2000-04-19

102

Optical and X-ray studies of chromospherically active stars: FR Cancri, HD 95559 and LO Pegasi  

NASA Technical Reports Server (NTRS)

We present a multiwavelength study of three chromospherically active stars, namely FR Cnc (= BD +16 degrees 1753), HD 95559 and LO Peg (=BD +22 degrees 4409), including newly obtained optical photometry, (for FR Cnc) low-resolution optical spectroscopy, as well as archival IR and X-ray observations. The BVR photometry carried out during the years 2001 - 2004 has found significant photometric variability to be present in all three stars. For FR Cnc, a photometric period 0.826685 +/- 0.000034 d has been established. The strong variation in the phase and amplitude of the FR Cnc light curves when folded on this period implies the presence of evolving and migrating spots or spot groups on its surface. Two independent spots with migration periods of 0.97 and 0.93 years respectively are inferred. The photometry of HD 95559 suggests the formation of a spot (group) during the interval of our observations. We infer the existence of two independent spots or groups in the photosphere of LO Peg, one of which has a migration period of 1.12 years. The optical spectroscopy of FR Cnc carried out during 2002-2003, reveals the presence of strong and variable Ca I1 H and K, H(sub beta) and H(sub alpha) emission features indicative of high level of chromospheric activity. The value of 5.3 for the ratio of the excess emission in H(sub alpha) to H(sub beta), EH(sub alpha)/EH(sub beta), suggests that the chromospheric emission may arise from an extended off-limb region. We have searched for the presence of color excesses in the near-IR JHK bands of these stars using 2MASS data, but none of them appear to have any significant color excess. We have also analyzed archival X-ray observations of HD 95559 and LO Peg carried out by with the ROSAT observatory. The best fit models to their X-ray spectra imply the presence of two coronal plasma components of differing temperatures and with sub-solar metal abundances. The inferred emission measures and temperatures of these systems are similar to those found for other active dwarf stars. The kinematics of FR Cnc suggest that it is a very young (35 - 55 Myrs) main-sequence star and a possible member of the IC 2391 supercluster. LO Peg also has young disk-type kinematics and has been previously suggested to be a member of the 100 Mys old Local Association (Pleiades Moving Group). The kinematics of HD 95559 indicate it is a possible member of the 600 Myrs old Hyades supercluster.

Pandey, J. C.; Singh, K. P.; Drake, S. A.; Sagar, R.

2005-01-01

103

Fast fabrication of high-gradient optical aspheric surface by CNC machine  

NASA Astrophysics Data System (ADS)

For fabricating a high gradient aspherics, we have designed a ZDCCOS complex, which consist of a CNC Polisher and a CQG- II digital wavefront interferometer. The Polisher has 5 degrees of freedom. The computer makes a small tool to move in three dimensions and drive the workpiece to sway, and turn around simultaneously to keep the pad in the normal directions of the workpiece surface. We designed a special dual-rotation tool and presented a new model to calculate the removal function of which. the model was verified by the experiments. The track programming algorithm was also designed to make the tools to move on spatial concentric circles, during the fabrication processes. The work piece was a (Phi) 300 mm, F5.9 focus lens, the aspheric degree of which was up to 46 micrometers . But only after 8 hours 43 minutes continuous fine grinding, and about 15 hours polishing, the surface error was decreased to 1(lambda) (Rms, (lambda) equals 0.6328 micrometers ).

Zheng, Weimin; Cao, Tianning; Xu, Yanzhou; Qian, Min

1998-08-01

104

An Expanding Shell and Synchrotron Jet in RS Ophiuchi  

E-print Network

We report high-resolution radio imaging of the recurrent nova RS Ophiuchi (RS Oph) during the first month of the 2006 outburst, using the Very Long Baseline Array (VLBA). Observations made on days 20.8 and 26.8 of the outburst show a synchrotron-emitting partial shell that is much brighter to the east than to the west. Assuming the broad component of the infrared lines corresponds to the outermost part of the shell seen by the VLBA, the distance to the source is $2.45\\pm0.4 kpc$. The circular shape and spectral indices of the shell emission challenge simple models for the radio structure immediately after the outburst. The second epoch also shows an additional, resolved, synchrotron-emitting component well to the east of the shell. Its inferred velocity is comparable to the escape speed from the surface of a high-mass white dwarf. This component was not seen in the first epoch. Its appearance may be related to the outflow reaching the edge of the nebula created by the red giant wind, which had been re-filling the void left by the last outburst in 1985. This eastern component is likely related to the jets previously seen in this and other symbiotic stars, and represents the earliest clear detection of such a jet, as well as the best case yet for synchrotron emission from a white dwarf jet.

Michael P. Rupen; Amy J. Mioduszewski; Jennifer L. Sokoloski

2007-11-07

105

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

106

Gravitational quantization of exoplanet orbits in 55 Cnc, $\\upsilon$ And, Kepler-11, Kepler-20, and Kepler-90  

E-print Network

In the framework of the so-called "global polytropic model", we assume hydrostatic equilibrium for a planetary system, and solve the resulting Lane--Emden differential equation in the complex plane. We thus obtain polytropic spherical shells defined by succesive roots of the real part $\\mathrm{Re}(\\theta)$ of the Lane-Emden function $\\theta$. These shells seem to provide hosting orbits for the planets of the system(s) under consideration. In the present investigation, we study within this framework the exoplanet systems 55 Cnc, $\\upsilon$ And, Kepler-11, Kepler-20, and Kepler-90.

Geroyannis, Vassilis S

2014-01-01

107

Effect of a gelatin-based edible coating containing cellulose nanocrystals (CNC) on the quality and nutrient retention of fresh strawberries during storage  

NASA Astrophysics Data System (ADS)

Strawberry is a non-climacteric fruit with a very short postharvest shelf-life. Loss of quality in this fruit is mostly due to its relatively high metabolic activity and sensitivity to fungal decay, meanly grey mold (Botrytis cinerea). In this study, the ability of gelatin coatings containing cellulose nanocrystals (CNC) to extend the shelf-life of strawberry fruit (Fragaria ananassa) over 8 days were studied. The filmogenic solution was obtained by the hydration of 5 g of gelatin (GEL) in 100 mL of distillated water containing different amounts of CNC dispersion (10 mg CNC/g of GEL or 50 mg of CNC/g of GEL) for 1 hour at room temperature. After this period, the solution was heated to 70 °C and maintained at this temperature for 10 minutes. The plasticizer (glycerol) (10g/100g of the GEL) was then added with constant, gentle stirring in order to avoid forming air bubbles and also to avoid gelatin denaturation until complete homogenization. Strawberries (purchased at the local market) were immersed in the filmogenic solution for 1 minute and after coated were dried at 15 °C by 24 hours. The strawberries were then kept under refrigeration and characterized in terms of their properties (weight loss, ascorbic acid content, titratable acidity, water content). The results have shown that samples covered with GEL/CNC had a significant improvement in its shelf- life. For instance, for the control sample (without coating) the weight loss after 8 days of storage was around 65%, while covered samples loss in the range of 31-36%. Edible coating was also effective in the retention of ascorbic acid (AA) in the strawberries, while control sample presented a fast decay in the AA content, covered samples showed a slow decay in the AA concentration. Moreover, the use of GEL/CNC edible coating had an antimicrobial effect in the fruits.

Fakhouri, F. M.; Casari, A. C. A.; Mariano, M.; Yamashita, F.; Innocnentini Mei, L. H.; Soldi, V.; Martelli, S. M.

2014-08-01

108

LINGO1 rs9652490 and rs11856808 polymorphisms are not associated with risk for multiple sclerosis  

PubMed Central

Background Some recent experimental data suggest a possible role of LINGO-1 in the pathogenesis of multiple sclerosis (MS). In an attempt to identify genetic biomarkers related to MS susceptibility, we genotyped two common SNPs in the LINGO1 gene which have been associated to other neurological conditions, in patients with MS and in healthy subjects. These SNPs are linked to several SNPs within the LINGO1 gene, especially in individuals of Oriental or Caucasian descent. Methods We analyzed the allelic and genotype frequency of two LINGO1 variants (rs9652490 and rs11856808) in 293 patients with MS and 318 healthy controls, using KASPar assays. Results LINGO1 rs9652490 and rs11856808 allelic and genotype frequencies did not differ significantly between MS patients and controls. The minor allele frequencies for rs9652490 were 0.171 (95% CI?=?0.140-0.201) and 0.167 (95% CI?=?0.138-0.196 for cases and controls respectively (p?=?0.853). For rs11856808 the minor allele frequencies were 0.317 (95% CI?=?0.280-0.355) and 0.310 (95% CI?=?0.274-0.346) for cases and controls, respectively (p?=?0.773). Allele and genotype frequencies were unrelated with the age of onset of MS, gender, and clinical course of MS. In addition, haplotype analyses did not reveal any putative risk related to haplotypes. Conclusions These results suggest that LINGO1 rs9652490 and rs11856808 polymorphisms are not related with risk for MS. This study adds to other published evidence indicating that, to date, the LINGO1 SNPs studied here could be useful risk biomarkers of developing essential tremor, but not other movement disorders. PMID:23574883

2013-01-01

109

57ime CONGRS CANADIEN DE GOTECHNIQUE 57TH CANADIAN GEOTECHNICAL CONFERENCE 5ime CONGRS CONJOINT SCG/AIH-CNN 5TH JOINT CGS/IAH-CNC CONFERENCE  

E-print Network

CONJOINT SCG/AIH-CNN 5TH JOINT CGS/IAH-CNC CONFERENCE SIMULATING ACID MINE DRAINAGE THROUGH MINE WASTES Québec ABSTRACT The evolution of acid mine drainage (AMD) from reactive mine wastes is simulated using that sulphide oxidation and acid mine drainage can be significantly reduced using capillary barriers

Aubertin, Michel

110

An asymmetric shock wave in the 2006 outburst of the recurrent nova RS Ophiuchi.  

PubMed

Nova outbursts take place in binary star systems comprising a white dwarf and either a low-mass Sun-like star or, as in the case of the recurrent nova RS Ophiuchi, a red giant. Although the cause of these outbursts is known to be thermonuclear explosion of matter transferred from the companion onto the surface of the white dwarf, models of the previous (1985) outburst of RS Ophiuchi failed to adequately fit the X-ray evolution and there was controversy over a single-epoch high-resolution radio image, which suggested that the remnant was bipolar rather than spherical as modelled. Here we report the detection of spatially resolved structure in RS Ophiuchi from two weeks after its 12 February 2006 outburst. We track an expanding shock wave as it sweeps through the red giant wind, producing a remnant similar to that of a type II supernova but evolving over months rather than millennia. As in supernova remnants, the radio emission is non-thermal (synchrotron emission), but asymmetries and multiple emission components clearly demonstrate that contrary to the assumptions of spherical symmetry in models of the 1985 explosion, the ejection is jet-like, collimated by the central binary whose orientation on the sky can be determined from these observations. PMID:16855585

O'Brien, T J; Bode, M F; Porcas, R W; Muxlow, T W B; Eyres, S P S; Beswick, R J; Garrington, S T; Davis, R J; Evans, A

2006-07-20

111

Oldenlandia affinis (R&S) DC  

Microsoft Academic Search

A review of the geographical distribution, clinical use, biological activity and phytochemistry of Oldenlandia affinis (R&S) DC. is presented. During an inventory of medicinal plants in northern Congo\\/Brazzaville and south-western Central African Republic in 1962, 196 different species were registered, one of which was O. affinis used for the facilitation of childbirth. A medical team working in Luluabourg (Kananga) in

Lorents Gran; Finn Sandberg; Knut Sletten

2000-01-01

112

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

E-print Network

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 < 1000d 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.

Jean-Claude Mermilliod; Michel Mayor

1999-11-22

113

Association of Adiponectin rs1501299 and rs266729 Gene Polymorphisms With Nonalcoholic Fatty Liver Disease  

PubMed Central

Background Genetic and environmental factors are important for the development of nonalcoholic fatty liver disease (NAFLD). Adiponectin is a white and brown adipose tissue hormone, and have been found to play essential roles in the regulation of energy homoeostasis. Recent reports have identified a possible role of adiponectin in NAFLD via PPAR? pathway. Objectives The present study was designed to find out the impact of adiponectin rs1501299 (276G/T) and rs266729 (-11377C/G) gene polymorphisms in NAFLD. Patients and Methods Eighty-three patients with diagnosis of NAFLD, and 93 healthy subjects were included in the study. Tetra ARMS-PCR was designed to detect single nucleotide polymorphisms. Results A significant difference was found between NAFLD and control group regarding the rs266729 polymorphism (?2 = 7.35, P = 0.025). The rs266729 polymorphism increased the risk of NAFLD in codominant (CC vs. CG: OR = 2.18, 95% CI = 1.16 - 4.12, P = 0.016) and dominant (CC vs. CG/GG: OR = 2.31, 95% CI = 1.25 - 4.27; P = 0.008) inheritance tested models. The G allele increased the risk of NAFLD (OR = 1.63, 95% CI = 1.03 - 2.57, P = 0.037) in comparison with C allele. No significant difference was found between the groups concerning adiponectin rs1501299 gene polymorphism (?2 = 0.70, P = 0.697). Conclusions adiponectin rs266729 polymorphism might be a candidate gene, which determines the susceptibility to NAFLD. Larger studies are necessary to confirm these findings in various populations. PMID:23922565

Hashemi, Mohammad; Hanafi Bojd, Hamideh; Eskandari Nasab, Ebrahim; Bahari, Ali; Hashemzehi, Noor Allah; Shafieipour, Sara; Narouie, Behzad; Taheri, Mohsen; Ghavami, Saeid

2013-01-01

114

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 32…

Eason, Oliver

115

Analysis of the functional specificity of RS domains in vivo.  

PubMed Central

A number of splicing factors contain extensive regions that are rich in arginine and serine (RS domains). These domains are thought to facilitate protein-protein interactions that are critical in the regulation of alternative splicing. Using a domain swap strategy, we have tested the ability of RS domains from several proteins to substitute in vivo for an essential RS domain in the Drosophila splicing regulator TRA-2. By several criteria, RS domains were found to vary significantly in their ability to support the splicing regulation functions of TRA-2. The RS domain of dU2AF50 functioned efficiently, while that of the dSRp55 protein did not. Moreover, we find similar differences in the ability of RS domains to direct fusion proteins to discrete subnuclear sites at which TRA-2 associates with spermatocyte chromosomes. These results indicate that RS domains are not all functionally equivalent in vivo. PMID:9774348

Dauwalder, B; Mattox, W

1998-01-01

116

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

117

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

118

Association of obesity with rs1421085 and rs9939609 polymorphisms of FTO gene.  

PubMed

The aim of this study is to investigate the genetic influence of polymorphisms in fat mass and obesity associated (FTO) gene on a sample of obese subjects and controls. Obesity is an epidemic all over the world. Several polymorphisms in the first intron of FTO gene have been associated with common forms of human obesity. In this research rs1421085 and rs9939609 polymorphisms of FTO gene were genotyped in 190 obese patients with a BMI ?30 kg/m(2) (Body Mass Index) and 97 healthy controls with a BMI of 18.5-24.9. Genotyping of SNPs was performed by real-time polymerase chain reaction. Body composition was established with bioelectric impedance analysis. Waist-to-hip ratio was determined for all participants. There were no significant differences (P > 0.05) between obese cases and controls in terms of genotype frequencies of rs1421085 and rs9939609 polymorphisms in our study. Also there were no significant correlations between genotypes and obesity related (anthropometric-body composition) parameters (P > 0.05). PMID:25074273

Solak, Mustafa; Ozdemir Erdogan, Mujgan; Yildiz, Saliha Handan; Ucok, Kagan; Yuksel, Seref; Ar?kan Terzi, Evrim Suna; Bestepe, Ahmet

2014-11-01

119

Long-term study of the starspot activity on the eclipsing short-period RS Canum Venaticorum binary UV Piscium  

NASA Astrophysics Data System (ADS)

We present optical photometry of the short-period eclipsing RS CVn system, UV Piscium for the years 1966-1984. For each light curve, we model the distortion waves in order to study the behaviour of starspots in this system. After removing the spot effects from the light curves, we model the cleaned data to obtain system parameters. We also note changes in the luminosity of the primary star that are not explained by the spot variation.

Radhika, P.; Vivekananda Rao, P.

2001-09-01

120

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

121

Unified error model based spatial error compensation for four types of CNC machining center: Part II-unified model based spatial error compensation  

NASA Astrophysics Data System (ADS)

In this paper, a spatial error compensation method was proposed for CNC machining center based on the unified error model. The spatial error distribution was analyzed in this research. The result shows that the spatial error is relative to each axis of a CNC machine tool. Moreover, the spatial error distribution is non-linear and there is no regularity. In order to improve the modeling accuracy and efficiency, an automatic error modeling application was designed based on the orthogonal polynomials. To realize the spatial error compensation, a multi-thread parallel processing mode based error compensation controller was designed. Using the spatial error compensation method, the machine tools' accuracy is greatly improved compared to that with no compensation.

Fan, Kaiguo; Yang, Jianguo; Yang, Liyan

2014-12-01

122

An RS-170 to 700 frame per second CCD camera  

SciTech Connect

A versatile new camera, the Los Alamos National Laboratory (LANL) model GY6, is described. It operates at a wide variety of frame rates, from RS-170 to 700 frames per second. The camera operates as an NTSC compatible black and white camera when operating at RS-170 rates. When used for variable high-frame rates, a simple substitution is made of the RS-170 sync/clock generator circuit card with a high speed emitter-coupled logic (ECL) circuit card.

Albright, K.L.; King, N.S.P.; Yates, G.J.; McDonald, T.E. [Los Alamos National Lab., NM (United States); Turko, B.T. [Lawrence Berkeley Lab., CA (United States)

1993-08-01

123

X-Ray Emitting Blast Wave from the Recurrent Nova RS Ophiuchi  

E-print Network

Stellar explosions such as novae and supernovae produce most of the heavy elements in the Universe. Although the onset of novae from runaway thermonuclear fusion reactions on the surface of a white dwarf in a binary star system is understood[1], 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; the explosion products plow through the nebula and produce X-ray emission. Early this year, an eruption of the recurrent nova RS Ophiuchi[2,3] provided the first opportunity to perform comprehensive X-ray observations of such an event and diagnose conditions within the ejecta. Here we show that 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 due to interaction with the nebula. The X-rays faded rapidly, suggesting that the blast wave deviates from the standard spherical shell structure[4-6]. The early onset of deceleration indicates that the ejected shell had a low mass, the white dwarf has a high mass[7], and that RS Ophiuchi is a progenitor of the type of supernova integral to studies of the expansion of the universe.

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

2006-05-12

124

OPMILL - MICRO COMPUTER PROGRAMMING ENVIRONMENT FOR CNC MILLING MACHINES THREE AXIS EQUATION PLOTTING CAPABILITIES  

NASA Technical Reports Server (NTRS)

OPMILL is a computer operating system for a Kearney and Trecker milling machine that provides a fast and easy way to program machine part manufacture with an IBM compatible PC. The program gives the machinist an "equation plotter" feature which plots any set of equations that define axis moves (up to three axes simultaneously) and converts those equations to a machine milling program that will move a cutter along a defined path. Other supported functions include: drill with peck, bolt circle, tap, mill arc, quarter circle, circle, circle 2 pass, frame, frame 2 pass, rotary frame, pocket, loop and repeat, and copy blocks. The system includes a tool manager that can handle up to 25 tools and automatically adjusts tool length for each tool. It will display all tool information and stop the milling machine at the appropriate time. Information for the program is entered via a series of menus and compiled to the Kearney and Trecker format. The program can then be loaded into the milling machine, the tool path graphically displayed, and tool change information or the program in Kearney and Trecker format viewed. The program has a complete file handling utility that allows the user to load the program into memory from the hard disk, save the program to the disk with comments, view directories, merge a program on the disk with one in memory, save a portion of a program in memory, and change directories. OPMILL was developed on an IBM PS/2 running DOS 3.3 with 1 MB of RAM. OPMILL was written for an IBM PC or compatible 8088 or 80286 machine connected via an RS-232 port to a Kearney and Trecker Data Mill 700/C Control milling machine. It requires a "D:" drive (fixed-disk or virtual), a browse or text display utility, and an EGA or better display. Users wishing to modify and recompile the source code will also need Turbo BASIC, Turbo C, and Crescent Software's QuickPak for Turbo BASIC. IBM PC and IBM PS/2 are registered trademarks of International Business Machines. Turbo BASIC and Turbo C are trademarks of Borland International.

Ray, R. B.

1994-01-01

125

Genetic Variations rs11892031 and rs401681 Are Associated with Bladder Cancer Risk in a Chinese Population.  

PubMed

Genome-wide association studies (GWAS) have identified a number of genetic variants associated with risk of bladder cancer in populations of European descent. Here, we assessed association of two of these variants, rs11892031 (2q37.1 region) and rs401681 (5p15.33 region) in a Chinese case-control study, which included 367 bladder cancer cases and 420 controls. We found that the AC genotype of rs11892031 was associated with remarkably decreased risk of bladder cancer (adjusted odds ratio (OR), 0.27; 95% confidence interval (CI), 0.09-0.81; p = 0.019), compared with the AA genotype of rs11892031; and that CT/CC genotypes of rs401681 were associated with significantly increased risk of bladder cancer (adjusted OR, 1.79; 95% CI, 1.10-2.91; p = 0.02), compared with the TT genotype of rs401681. We further conducted stratification analysis to examine the correlation between single nucleotide polymorphism (SNP) rs11892031/rs401681 and tumor grade/stage. Results showed that heterogeneity in ORs of tumor categories was not significant for either rs11892031 or rs401681 (p > 0.05), indicating that the two SNPs seemingly do not associate with tumor grade and stage of bladder cancer in our study population. The present study suggests that the SNPs rs11892031 and rs401681 are associated with bladder cancer risk in a Chinese population. Future analyses will be conducted with more participants recruited in a case-control study. PMID:25347272

Zhang, Yu; Sun, Yan; Chen, Tao; Hu, Hailong; Xie, Wanqin; Qiao, Zhihui; Ding, Na; Xie, Linguo; Li, Sheng; Wang, Wenlong; Xing, Chen; Wang, Yihan; Qie, Yunkai; Wu, Changli

2014-01-01

126

Structure of the ArgRS-GlnRS-AIMP1 complex and its implications for mammalian translation.  

PubMed

In higher eukaryotes, one of the two arginyl-tRNA synthetases (ArgRSs) has evolved to have an extended N-terminal domain that plays a crucial role in protein synthesis and cell growth and in integration into the multisynthetase complex (MSC). Here, we report a crystal structure of the MSC subcomplex comprising ArgRS, glutaminyl-tRNA synthetase (GlnRS), and the auxiliary factor aminoacyl tRNA synthetase complex-interacting multifunctional protein 1 (AIMP1)/p43. In this complex, the N-terminal domain of ArgRS forms a long coiled-coil structure with the N-terminal helix of AIMP1 and anchors the C-terminal core of GlnRS, thereby playing a central role in assembly of the three components. Mutation of AIMP1 destabilized the N-terminal helix of ArgRS and abrogated its catalytic activity. Mutation of the N-terminal helix of ArgRS liberated GlnRS, which is known to control cell death. This ternary complex was further anchored to AIMP2/p38 through interaction with AIMP1. These findings demonstrate the importance of interactions between the N-terminal domains of ArgRS and AIMP1 for the catalytic and noncatalytic activities of ArgRS and for the assembly of the higher-order MSC protein complex. PMID:25288775

Fu, Yaoyao; Kim, Youngran; Jin, Kyeong Sik; Kim, Hyun Sook; Kim, Jong Hyun; Wang, DongMing; Park, Minyoung; Jo, Chang Hwa; Kwon, Nam Hoon; Kim, Doyeun; Kim, Myung Hee; Jeon, Young Ho; Hwang, Kwang Yeon; Kim, Sunghoon; Cho, Yunje

2014-10-21

127

Intermittent process measurement and process capability analysis using MP700 touch trigger probe on a CNC machining center  

NASA Astrophysics Data System (ADS)

This study developed an intermittent process measurement system by integrating a MP700 touch trigger probe system with a machining center to measure a workpiece containing freeform surface and regular geometric features, and to do the statistical process control analysis. The whole measuring system, consisting of a personal computer, a CNC machining center controller, a RENISHAW MP700 touch probe system, was integrated information-technically. Measuring software was also developed to simulate the measuring path, to prevent collision, to generate the corresponding measuring NC codes and to calculate the process capability indices, such as the process capability index (Cp), the process performance index (C PK) and the accuracy capability index (Ca). To evaluate the performance of the developed measuring system, a carrier combined with a freeform surface and regular geometric features, referred to in the ISO 10791-7 cutting test standard, was designed. Six pieces of the tested carriers were manufactured and inspected using the MP700 touch trigger probe to evaluate the performance of the developed measuring system. According to the measuring results, the developed measuring system was successfully and effectively used to carry out the intermittent process measurement and the statistical process analysis of the measuring results of some test carriers on the machining center.

Shiou, Fang-Jung; Su, Po-Chuan

2006-11-01

128

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

129

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

130

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

131

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

132

RS170 to 700 frame per second CCD camera  

Microsoft Academic Search

A versatile new camera, the Los Alamos National Laboratory (LANL) model GY6, is described. It operates at a wide variety of frame rates, from RS-170 to 700 frames per second. The camera operates as an NTSC compatible black and white camera when operating at RS- 170 rates. When used for variable high-frame rates, a simple substitution is made of the

Kevin L. Albright; Nicholas S. King; George J. Yates; Thomas E. McDonald; Bojan T. Turko

1993-01-01

133

309-04/GAN/rs G.A. Navratil  

E-print Network

309-04/GAN/rs by G.A. Navratil Presented at Forty-sixth Annual Meeting American Physical Society;309-04/GAN/rs by G.A. Navratil Presented at Forty-sixth Annual Meeting American Physical Society Division] OF KINK MODE BEHAVIOR · EXTENSION OF THE MODEL TO ACTIVE FEEDBACK CONTROL OF THE KINK MODE #12;W = 1-- 2

134

Molecular Cell LysRS Serves as a Key Signaling  

E-print Network

, we used LysRS silencing in mast cells in combination with transfected normal and mutated Lys produc- tion in immunologically activated cells, which re- sulted in a lower level of MITF inducible in immu- nologically stimulated mast cells, thus implying that LysRS is a key mediator in gene regulation

Lebendiker, Mario

135

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

136

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

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

137

Scintillating Stars  

NSDL National Science Digital Library

Often, a bright planet that is visible over the horizon will be mistaken for a star. Some believe they can tell the difference between a star and a planet because stars twinkle, or scintillate , and planets do not. In actuality however, both will twinkle because any light that passes through our atmosphere, whether it be reflected from a planet or generated by a star, will be interfered with by the atmospheric elements. This month's column sheds light on this "scintillating" subject and engages students in a research activity that revolves around the question: Is Pluto a planet?

Riddle, Bob

2003-02-01

138

Neutron Stars  

NASA Technical Reports Server (NTRS)

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

Cottam, J.

2007-01-01

139

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

140

Period04 FCAPT uvby Photometric Studies of Eight Magnetic CP Stars  

NASA Astrophysics Data System (ADS)

We present Four College Automated Photometric Telescope (FCAPT) differential Stromgren uvby photometry of 8 magnetic CP (mCP) stars: HD 5797 (V551 Cas), HD 26792 (DH Cam), HD 27309 (56 Tau, V724 Tau), HD 49713 (V740 Mon), HD 74521 (49 Cnc, BI Cnc), HD 120198 (84 UMa, CR UMa), HD 171263 (QU Ser), and HD 215441 (GL Lac, Babcock's star). Our data sets are larger than those of most mCP stars in the literature. These are the first FCAPT observations of HD 5797, HD 26792, HD 49713, and HD 171263. Those for the remaining four stars substantially extend published FCAPT data. The FCAPT observed some stars for a longer time range and with greater accuracy than other optical region automated photometric telescopes.Our goals were to determine very accurate periods, the u, v, b, and y amplitudes, and if there were any long period periods. In addition we wanted to compare our results with those of magnetic field measurements to help interpret the light curves.We used the Period04 computer program to analyze the light curves. This program provides errors for the derived quantities as it fits the light curve. Our derived periods of 68.046 +/- 0.008 days for HD 5797, 3.80205 +/- 0.00006 days for HD 26792, 1.56889 +/- 0.000002 days for HD 27309, 2.13536 +/- 0.00002 days for HD 49713, 7.0505 +/- 0.0001 days for HD 74521, 1.38577 +/- 0.000004 days for HD 120198, 3.9974 +/- 0.0001days for HD 171263, and 9.487792 +/- 0.00005 days for HD 215441 are refinements of the best determinations in the literature.

Adelman, Saul J.; Dukes, Robert J.

2014-06-01

141

Leukocyte Telomere Length-Related rs621559 and rs398652 Genetic Variants Influence Risk of HBV-Related Hepatocellular Carcinoma  

PubMed Central

Recent genome-wide association studies (GWAS) have identified eleven leukocyte telomere length (LTL)-related single nucleotide polymorphisms (SNPs). Since LTL has been associated with risk of many malignancies, LTL-related SNPs may contribute to cancer susceptibility. To test this hypothesis in hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC), we genotyped these eleven LTL-related SNPs in a case-control set including 1186 HBV-related HCC cases, 508 chronic HBV carriers and 1308 healthy controls at the discovery stage. The associations of HCC risk with these SNPs were further confirmed in an independent case-control set. We found that 1p34.2 rs621559 and 14q21 rs398652 were significantly associated with HBV-related HCC risk (both P<0.005 after Bonferroni corrections). There was no significant difference of either rs621559 or rs398652 genotypes between chronic HBV carriers and healthy controls, demonstrating that the association was not due to predisposition to HBV infection. In the pooled analyses (1806 HBV-related HCC cases and 1954 controls), we observed a decreased HCC risk, 0.72-times, associated with the 1p34.2 rs621559 AA genotype compared to the GG genotype (P?=?1.6×10?6). Additionally, there was an increased HCC risk, 1.27-fold, associated with the rs398652 GG genotype (P?=?3.3×10?6). A statistical joint effect between the rs621559 GG and rs398652 GG genotypes may exist in elevating risk of HBV-related HCC. We show, for the first time, that rs398652 and rs621559 might be marker genetic variants for risk of HBV-related HCC in the Chinese population. PMID:25365256

Shi, Juan; Lu, Chao; Wei, Jinyu; Li, Lichao; Zhou, Changchun; Yuan, Qipeng; Zhou, Liqing; Yang, Ming

2014-01-01

142

Rs7206790 and rs11644943 in FTO Gene Are Associated with Risk of Obesity in Chinese School-Age Population  

PubMed Central

To evaluate the associations between candidate FTO single nucleotide polymorphisms (SNPs) and obesity, a case-control study was conducted among Chinese school-age children, which included 500 obese cases and 500 matched controls (age, gender and location). We selected 24 candidate FTO tag-SNPs via bio-informatics analysis and performed genotyping using SNPScan technology. Results indicated that rs7206790 and rs11644943 were significantly associated with obesity among school-age children in both additive and recessive models (P<0.05) after adjusting confounders. Comparing rs7206790 CC and CG genotype of carriers, those carrying the GG genotype had an increased risk of obesity (adjusted odds ratio [OR], 3.76; 95% Confidence interval [CI], 1.24–11.43). Carriers of the AA allele of rs11644943 had a lower risk of obesity (adjusted OR, 0.16; 95% CI, 0.04–0.72) compared with those of the T allele (TT and TA). These two SNPs (rs7206790 and rs11644943) were not Linkage Disequilibrium (LD) with previous reported obesity-associated SNPs. Under the recessive model adjusted for age and gender and location, rs7206790 GG allele carriers had significantly increased BMIs (P?=?0.012), weight (P?=?0.012), waist circumferences (WC) (P?=?0.045) and hip circumferences (HC) (P?=?0.033). Conversely, rs11644943 AA allele carriers had significantly decreased BMIs (P?=?0.006), WC (P?=?0.037) and Waist-to-height ratios (WHtR) (P?=?0.012). A dose-response relationship was found between the number of risk alleles in rs7206790, rs11644943 and rs9939609 and the risk of obesity. The Genetic Risk Score (GRS) of the reference group was 3; in comparison, those of 2, 4, and ?5 had ORs for obesity of 0.24 (95%CI, 0.05–1.13), 1.49 (95%CI, 1.10–2.01), and 5.20 (95%CI, 1.75–15.44), respectively. This study confirmed the role of FTO variation on genetic susceptibility to obesity. We reported two new obesity-related FTO SNPs (rs7206790 and rs11644943) among Chinese school-age children. PMID:25251416

Xu, Yuyang; Ling, Jie; Yang, Min; Wang, Hao; Zhang, Shuai; Zhang, Xuhui; Zhu, Yimin

2014-01-01

143

RS-34 Phoenix (Peacekeeper Post Boost Propulsion System) Utilization Study  

NASA Technical Reports Server (NTRS)

The Advanced Concepts Office (ACO) at the NASA Marshall Space Flight Center (MSFC) in conjunction with Pratt & Whitney Rocketdyne conducted a study to evaluate potential in-space applications for the Rocketdyne produced RS-34 propulsion system. The existing RS-34 propulsion system is a remaining asset from the decommissioned United States Air Force Peacekeeper ICBM program; specifically the pressure-fed storable bipropellant Stage IV Post Boost Propulsion System, renamed Phoenix. MSFC gained experience with the RS-34 propulsion system on the successful Ares I-X flight test program flown in October 2009. RS-34 propulsion system components were harvested from stages supplied by the USAF and used on the Ares I-X Roll control system (RoCS). The heritage hardware proved extremely robust and reliable and sparked interest for further utilization on other potential in-space applications. Subsequently, MSFC is working closely with the USAF to obtain all the remaining RS-34 stages for re-use opportunities. Prior to pursuit of securing the hardware, MSFC commissioned the Advanced Concepts Office to understand the capability and potential applications for the RS-34 Phoenix stage as it benefits NASA, DoD, and commercial industry. Originally designed, the RS-34 Phoenix provided in-space six-degrees-of freedom operational maneuvering to deploy multiple payloads at various orbital locations. The RS-34 Phoenix Utilization Study sought to understand how the unique capabilities of the RS-34 Phoenix and its application to six candidate missions: 1) small satellite delivery (SSD), 2) orbital debris removal (ODR), 3) ISS re-supply, 4) SLS kick stage, 5) manned GEO servicing precursor mission, and an Earth-Moon L-2 Waypoint mission. The small satellite delivery and orbital debris removal missions were found to closely mimic the heritage RS-34 mission. It is believed that this technology will enable a small, low-cost multiple satellite delivery to multiple orbital locations with a single boost. For both the small satellite delivery and the orbital debris mission candidates, the RS-34 Phoenix requires the least amount of modification to the existing hardware. The results of the RS-34 Phoenix Utilization Study show that the system is technically sufficient to successfully support all of the missions analyzed

Esther, Elizabeth A.; Kos, Larry; Bruno, Cy

2012-01-01

144

RS-34 Phoenix (Peacekeeper Post Boost Propulsion System) Utilization Study  

NASA Technical Reports Server (NTRS)

The Advanced Concepts Office (ACO) at the NASA Marshall Space Flight Center (MSFC) in conjunction with Pratt & Whitney Rocketdyne conducted a study to evaluate potential in-space applications for the Rocketdyne produced RS-34 propulsion system. The existing RS-34 propulsion system is a remaining asset from the de-commissioned United States Air Force Peacekeeper ICBM program, specifically the pressure-fed storable bipropellant Stage IV Post Boost Propulsion System, renamed Phoenix. MSFC gained experience with the RS-34 propulsion system on the successful Ares I-X flight test program flown in October 2009. RS-34 propulsion system components were harvested from stages supplied by the USAF and used on the Ares I-X Roll control system (RoCS). The heritage hardware proved extremely robust and reliable and sparked interest for further utilization on other potential in-space applications. MSFC is working closely with the USAF to obtain RS-34 stages for re-use opportunities. Prior to pursuit of securing the hardware, MSFC commissioned the Advanced Concepts Office to understand the capability and potential applications for the RS-34 Phoenix stage as it benefits NASA, DoD, and commercial industry. As originally designed, the RS-34 Phoenix provided in-space six-degrees-of freedom operational maneuvering to deploy multiple payloads at various orbital locations. The RS-34 Phoenix Utilization Study sought to understand how the unique capabilities of the RS-34 Phoenix and its application to six candidate missions: 1) small satellite delivery (SSD), 2) orbital debris removal (ODR), 3) ISS re-supply, 4) SLS kick stage, 5) manned GEO servicing precursor mission, and an Earth-Moon L-2 Waypoint mission. The small satellite delivery and orbital debris removal missions were found to closely mimic the heritage RS-34 mission. It is believed that this technology will enable a small, low-cost multiple satellite delivery to multiple orbital locations with a single boost. For both the small satellite delivery and the orbital debris mission candidates, the RS-34 Phoenix requires the least amount of modification to the existing hardware. The results of the RS-34 Phoenix Utilization Study show that the system is technically sufficient to successfully support all of the missions analyzed.

Esther, Elizabeth A.; Kos, Larry; Burnside, Christopher G.; Bruno, Cy

2013-01-01

145

Enantioselective degradation of (2RS,3RS)-paclobutrazol in peach and mandarin under field conditions.  

PubMed

In this study we investigated the enantioselective degradation of (2RS,3RS)-paclobutrazol in peach and mandarin fruits under field conditions after foliar treatment at 500 mg active ingredient/L using a Lux Cellulose-1 chiral column on a reverse-phase liquid chromatography-tandem mass spectrometry system. Degradations of paclobutrazol in both fruits followed first-order kinetics, with half-lives of about 9 days. Initial deposits were 1.63 mg/kg on peach and 1.99 mg/kg on mandarin; terminal concentrations were lower than 0.05 mg/kg, which was acceptable in most cases. As anticipated, paclobutrazol levels in peels of mature mandarin were about 6.3 times higher than in pulp, indicating the potential risk of peel consumption. We also observed that paclobutrazol degradation in mature mandarin was relatively slow, indicating it might not be efficient enough to hold mandarin fruits on trees for lowering paclobutrazol concentrations. Significant enantioselectivity was observed: the (2R,3R)-enantiomer was preferentially degraded in mandarin (whole fruit, peels, and pulp) but enriched in peach. Because of its more rapid degradation in mandarin and the lower levels observed in pulp compared with peels, potential endocrine-related side effects due to the (2R,3R)-enantiomer pose less of a risk in mandarin than in peach. PMID:24890866

Wang, Xiangyun; Qi, Peipei; Yang, Guiling; Wang, Xinquan; Zhang, Hu; Xu, Hao; Wang, Zhiwei; Wang, Qiang

2014-08-01

146

Photometric and Ca II H and K Spectroscopic Variations in Nearby Sun-like Stars with Planets. III.  

NASA Astrophysics Data System (ADS)

We present the results of an analysis of time-series photometry, Ca II H and K spectrophotometry, and high-dispersion visible spectra of nine nearby Sun-like stars recently identified as having planets. For the six stars whose presumed planets have orbital periods of less than 4 months (? Boo, 51 Peg, ? And, ?1 Cnc, ? CrB, and 70 Vir), sine-curve fits to the photometric data show no variations with semiamplitude greater than 1 or 2 parts in 104. Photometric variations in 47 UMa are similarly small, although our photometric data of this star are slightly affected by variability of the comparison star. Nonvariability at this level of precision is sufficient to rule out surface magnetic activity as the cause of the observed radial-velocity variations in these seven stars and makes nonradial pulsations unlikely as well. Thus, our photometry provides indirect but strong support for true reflex motions-planets-in these seven stars, but cannot yet so support the planetary hypothesis for the two additional stars, 16 Cyg B and Gl 411. Continued photometric monitoring of the short-period systems may soon result in the direct detection of these planets in reflected light. We have used our photometric fluxes to search for possible transits of the extrasolar planets. Transits definitely do not occur in ? Boo, 51 Peg, ? And, and ?1 Cnc, and probably do not occur in ? CrB and 70 Vir. Our transit-search results are inconclusive for 47 UMa, and we cannot address the issue for 16 Cyg B and Gl 411. The precision of our photometry is sufficient to detect transits of planets even if they are not gas giants, as currently assumed, but much smaller objects with rocky compositions. The chance of finding at least one transit in the six stars is ~40%. We find significant year-to-year photometric variability only in ? Boo, which is not only the youngest star in the sample but also the star with the shallowest convective zone. The interseasonal range in its yearly mean photometric flux is ~0.002 mag, roughly twice the 0.0008 mag decadal variation in the Sun's total irradiance. Monitoring of the relative Ca II H and K fluxes began between 1966 and 1968 for 51 Peg, ? Boo, ? CrB, and Gl 411, between 1990 and 1993 for 47 UMa, 70 Vir, 16 Cyg B, and ?1 Cnc, and in 1996 for ? And. The data have been newly recalibrated for improved long-term instrumental stability, resulting in better precision of the Ca II records. Five of the nine stars in this study have little or no detectable year-to-year variation in Ca II flux. The remaining four show moderate or pronounced variability: ? Boo, whose radial-velocity and photometric variations have comparatively high amplitudes; Gl 411, whose planetary companion was inferred astrometrically, not spectroscopically; ?1 Cnc, which may undergo decadal cyclic activity; and ? And, which shows moderate year-to-year variability. Except for 47 UMa, intraseasonal variability consistent with rotation was detected in the Ca II records of all stars. However, the rotation periods determined for ? And, 70 Vir, and 16 Cyg B are of low confidence. An examination of the recalibrated Ca II records for 51 Peg finds a rotation period of 22 days, in contrast to our previous result of 37 days. Ages have been estimated from the mean Ca II flux and, where possible, the rotation period. We find general consistency with the ages determined by others comparing properties determined from high-resolution spectroscopy to evolutionary models, although the uncertainties are, in general, large. Based on observations made at Mount Wilson Observatory, operated by the Mount Wilson Institute, under an agreement with the Carnegie Institution of Washington and the automatic photoelectric telescope at Fairborn Observatory in the Patagonia Mountains of southern Arizona.

Henry, Gregory W.; Baliunas, Sallie L.; Donahue, Robert A.; Fekel, Francis C.; Soon, Willie

2000-03-01

147

8th Cool Stars, Stellar Systems and the Sun 1 A SEARCH FOR fl--RAY EMISSION FROM ACTIVE STARS  

E-print Network

Well, even the Sun, that feeble (by the standards of RS CVns and flare stars) orb, produces them the time, which requires the presence of ?500 keV electrons in the corona. Thus the electrons required is thought primarily to accelerate electrons to energies of 10--100 keV. These electrons then strike

White, Stephen

148

10 CFR 434.103 - Referenced standards (RS).  

...Administration and Enforcement-General § 434.103 Referenced standards (RS). 103.1 The standards, technical handbooks, papers and regulations listed in § 434.701, shall be considered part of this part to the prescribed extent of...

2014-01-01

149

10 CFR 434.103 - Referenced standards (RS).  

Code of Federal Regulations, 2010 CFR

...Administration and Enforcement-General § 434.103 Referenced standards (RS). 103.1The standards, technical handbooks, papers and regulations listed in § 434.701, shall be considered part of this part to the prescribed extent of...

2010-01-01

150

10 CFR 434.103 - Referenced standards (RS).  

Code of Federal Regulations, 2011 CFR

...Administration and Enforcement-General § 434.103 Referenced standards (RS). 103.1The standards, technical handbooks, papers and regulations listed in § 434.701, shall be considered part of this part to the prescribed extent of...

2011-01-01

151

10 CFR 434.103 - Referenced standards (RS).  

Code of Federal Regulations, 2013 CFR

...Administration and Enforcement-General § 434.103 Referenced standards (RS). 103.1The standards, technical handbooks, papers and regulations listed in § 434.701, shall be considered part of this part to the prescribed extent of...

2013-01-01

152

10 CFR 434.103 - Referenced standards (RS).  

Code of Federal Regulations, 2012 CFR

...Administration and Enforcement-General § 434.103 Referenced standards (RS). 103.1The standards, technical handbooks, papers and regulations listed in § 434.701, shall be considered part of this part to the prescribed extent of...

2012-01-01

153

Association of rs1568885, rs1813443 and rs4411591 polymorphisms with anti-TNF medication response in Greek patients with Crohn's disease  

PubMed Central

AIM: To investigate the correlation between rs1568885, rs1813443 and rs4411591 polymorphisms and response to infliximab in a cohort of Greek patients with Crohn’s disease (CD). METHODS: One hundred and twenty-six patients diagnosed with CD based on standard clinical, endoscopic, radiological, and pathological criteria were enrolled in this study at the Gastroenterology Unit of the 2nd Department of Surgery and at the Colorectal Unit of the 1st Department of Propaedeutic Surgery. Infliximab at a dose of 5 mg/kg was administered intravenously at weeks 0, 2, 6 and then every 8 wk. Clinical and serological responses were assessed using the Harvey-Bradshaw Index and serum C-reactive protein (CRP) levels, respectively, and the endoscopic response was evaluated by ileocolonoscopy performed at baseline and after 12-20 wk of therapy. The changes in endoscopic appearance compared to baseline were classified into four categories, and patients were classified as responders and non-responders. Genomic DNA from whole peripheral blood was extracted and genotyping was performed by allele-specific polymerase chain reactions. ?2 test with Yate’s correction based on the S-Plus was used to compare the genotype frequencies. RESULTS: Eighty patients (63.49%) were classified as complete and 32 (25.39%) as partial responders to infliximab, while 14 (11.11%) were primary non-responders. No correlation was found between response to infliximab and patients’ characteristics such as age, gender and disease duration. There was consistency between Harvey-Bradshaw index scores and serum CRP levels. The TT genotype of the rs1568885 polymorphism was significantly related to partial response (P = 0.024) and resistance to infliximab (P = 0.007) while the AT genotype was more frequent in partial responders (P = 0.035) and in primary non-responders (P = 0.032). Regarding rs1813443, the CC genotype was found to be associated with partial response (P = 0.005) and primary resistance (P = 0.002) to infliximab while no association was found between the rs4411591 polymorphism and the clinical response to infliximab. CONCLUSION: Based on our results, the rs1568885 and rs1813443 polymorphisms are associated with clinical and biochemical response to infliximab in Greek patients with Crohn’s disease. PMID:24707144

Thomas, Diamantis; Gazouli, Maria; Karantanos, Theodoros; Rigoglou, Stella; Karamanolis, Georgios; Bramis, Konstantinos; Zografos, George; Theodoropoulos, George E

2014-01-01

154

New insights into the dust formation of oxygen-rich AGB stars  

E-print Network

We observed the AGB stars S Ori, GX Mon and R Cnc with the MIDI instrument at the VLTI. We compared the data to radiative transfer models of the dust shells, where the central stellar intensity profiles were described by dust-free dynamic model atmospheres. We used Al2O3 and warm silicate grains. Our S Ori and R Cnc data could be well described by an Al2O3 dust shell alone, and our GX Mon data by a mix of an Al2O3 and a silicate shell. The best-fit parameters for S Ori and R Cnc included photospheric angular diameters Theta(Phot) of 9.7+/-1.0mas and 12.3+/-1.0mas, optical depths tau(V)(Al2O3) of 1.5+/-0.5 and 1.35+/-0.2, and inner radii R(in) of 1.9+/-0.3R(Phot) and 2.2+/-0.3R(Phot), respectively. Best-fit parameters for GX Mon were Theta(Phot)=8.7+/-1.3mas, tau(V)(Al2O3)=1.9+/-0.6, R(in)(Al2O3)=2.1+/-0.3R(Phot), tau(V)(silicate)=3.2+/-0.5, and R(in)(silicate)=4.6+/-0.2R(Phot). Our model fits constrain the chemical composition and the inner boundary radii of the dust shells, as well as the photospheric angula...

Karovicova, I; Ohnaka, K; Boboltz, D A; Fossat, E; Scholz, M

2013-01-01

155

Neutron stars  

NASA Astrophysics Data System (ADS)

Neutron stars are laboratories for dense matter and gravitational physics. Observations of neutron stars from sources such as radio pulsars, low-mass X-ray binaries, X-ray bursts and thermally-emitting neutron stars are setting bounds to neutron star masses, radii, rotation rates, temperatures and ages. Mass measurements constrain the equation of state at the highest densities and set firm bounds to the highest possible density of cold matter. Radii constrain the equation of state in the vicinity of the nuclear saturation density and yield information about the density dependence of the nuclear symmetry energy. Laboratory measurements and theoretical studies of pure neutron matter are in remarkable agreement with observational bounds.

Lattimer, James M.

2014-05-01

156

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

157

Star fruit  

Microsoft Academic Search

The carambola or star fruit belongs to the Oxalidaceae family, species Averrhoa carambola. Slices cut in cross-section have the form of a star (Figure 1). It is believed to have originated in Ceylon and the Moluccas\\u000a but it has been cultivated in southeast Asia and Malaysia for many centuries. It is commonly grown in some provinces in southern\\u000a China, in

Miguel M. Neto; Ruither O. Carolino; Norberto P. Lopes; Norberto Garcia-Cairasco

158

OxymiRs in Cutaneous Development, Wound Repair and Regeneration  

PubMed Central

The state of tissue oxygenation is widely recognized as a major microenvironmental cue that is known to regulate the expression of coding genes. Recent works have extended that knowledge to demonstrate that the state of tissue oxygenation may potently regulate the expression of microRNAs (miRs). Collectively, such miRs that are implicated in defining biological outcomes in response to a change in the state of tissue oxygenation may be referred to as oxymiRs. Broadly, oxymiRs may be categorized into three groups: (A) the existence (expression and/or turnover) of which is directly influenced by changes in the state of tissue oxygenation; (B) the existence of which is indirectly (e.g. oxygen-sensitive proteins, metabolites, pH etc) influenced by changes in the state of tissue oxygenation; and (C) those that modify biological outcomes to changes in the state of tissue oxygenation by targeting oxygen sensing pathways. This work represents the first review of how oxymiRs may regulate development, repair and regeneration. Currently known oxymiRs may affect the functioning of a large number of coding genes which have hitherto fore never been linked to oxygen sensing. Many of such target genes have been validated and that number is steadily growing. Taken together, our understanding of oxymiRs has vastly expanded the implications of changes in the state of tissue oxygenation. This emerging paradigm has major implications in untangling the complexities underlying diseases associated with ischemia and related hypoxic insult such as chronic wounds. PMID:23063665

Sen, Chandan K.; Roy, Sashwati

2013-01-01

159

OxymiRs in cutaneous development, wound repair and regeneration.  

PubMed

The state of tissue oxygenation is widely recognized as a major microenvironmental cue that is known to regulate the expression of coding genes. Recent works have extended that knowledge to demonstrate that the state of tissue oxygenation may potently regulate the expression of microRNAs (miRs). Collectively, such miRs that are implicated in defining biological outcomes in response to a change in the state of tissue oxygenation may be referred to as oxymiRs. Broadly, oxymiRs may be categorized into three groups: (A) the existence (expression and/or turnover) of which is directly influenced by changes in the state of tissue oxygenation; (B) the existence of which is indirectly (e.g. oxygen-sensitive proteins, metabolites, pH, etc.) influenced by changes in the state of tissue oxygenation; and (C) those that modify biological outcomes to changes in the state of tissue oxygenation by targeting oxygen sensing pathways. This work represents the first review of how oxymiRs may regulate development, repair and regeneration. Currently known oxymiRs may affect the functioning of a large number of coding genes which have hitherto fore never been linked to oxygen sensing. Many of such target genes have been validated and that number is steadily growing. Taken together, our understanding of oxymiRs has vastly expanded the implications of changes in the state of tissue oxygenation. This emerging paradigm has major implications in untangling the complexities underlying diseases associated with ischemia and related hypoxic insult such as chronic wounds. PMID:23063665

Sen, Chandan K; Roy, Sashwati

2012-12-01

160

Synaptic Pathology in Retinoschisis Knockout (Rs1?/y) Mouse Retina and Modification by rAAV-Rs1 Gene Delivery  

PubMed Central

Purpose At an early age, the retinoschisin knockout (Rs1-KO) mouse retina has progressive photoreceptor degeneration with severe disruption of the outer plexiform layer (OPL) that decreases at older ages. The electroretinogram (ERG) undergoes parallel changes. The b-wave amplitude from bipolar cells is reduced disproportionately to the photoreceptor a-wave at young but not at older ages. The protein expression and morphology of the OPL in Rs1-KO mice was investigated at different ages, to explore the role of the synaptic layer in these ERG changes. Methods Retinas of wild-type (Wt) and Rs1-KO mice from postnatal day (P)7 to 12 months were evaluated by light and electron microscopy (EM) and biochemistry. PSD95 (postsynaptic density protein), mGluR6 (metabotropic glutamate receptor subtype 6), retinoschisin (Rs1), the Müller cell proteins glial fibrillary acidic protein (GFAP) and glutamine synthetase (GS), the bipolar cell marker protein kinase C alpha (PKC?), and the horizontal cell marker calbindin were localized by immunofluorescence and immuno-EM. Levels of PSD95 and mGluR6 were determined by quantitative Western blot. Rs1-KO mice treated by intravitreous injection of rAAV(2/2)-CMV-Rs1 in one eye at P14 were evaluated at 8 months by full-field scotopic ERG responses and retinal immunohistochemistry. Results Rs1 was associated with the outer surface of synaptic membranes in wild-type (Wt) retinas. PSD95 and mGluR6 were juxtaposed in the OPL of the Rs1-KO retinas by P14, implying that synaptic structures are formed. Light microscopic retinal morphology was similar in Wt and Rs1-KO at P14, but by P21, the OPL was disrupted in Rs1-KO, and some PSD95 and mGluR6 was mislocalized in the outer nuclear layer (ONL). GFAP expression spanned all retinal layers. EM showed synaptic structures adjacent to photoreceptor nuclei. PSD95 and mGluR6 levels were normal at 1 month on Western blot but declined to 59% (P < 0.001) and 55% (P < 0.05) of Wt, respectively, by 4 months. Levels thereafter showed no further reduction out to 12 months. Eyes injected with AAV-Rs1 were studied at 8 months by immunohistochemistry and had higher expression of PSD95 and mGluR6 and less GFAP expression compared with fellow untreated eyes. Conclusions In the Rs1-KO mouse, retinal layer formation and synaptic protein expression in the OPL is normal up to P14, implying normal development of synaptic connections. Aberrant localization of synaptic proteins by P21 indicates that displacement of developing and/or mature synapses contributes to the b-wave reduction at young ages, when photoreceptor numbers and synaptic protein levels are normal. The subsequent decline in PSD95 and mGluR6 between 1 and 12 months in Rs1-KO retina mirrors the course of b-wave change and provides evidence of causal relationship between the ERG and OPL changes. These findings and the improved structural integrity of the OPL and b-wave amplitude after Rs1 gene transfer therapy provide a cellular and molecular basis for interpreting the changes in retinal signaling in this model. (Invest Ophthalmol Vis Sci. 2008; 49:3677-3686) DOI:10.1167/iovs.07-1071 PMID:18660429

Takada, Yuichiro; Vijayasarathy, Camasamudram; Zeng, Yong; Kjellstrom, Sten; Bush, Ronald A.; Sieving, Paul A.

2008-01-01

161

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

NASA Astrophysics Data System (ADS)

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 observational data are available. Aims: Deeper physical insight is needed regarding the inter-outburst accretion phase and the dynamical effects of the subsequent nova explosion in order to improve the interpretation of the observed data and to shed light on whether the system is an SNIa progenitor. Methods: We present a 3D hydrodynamic simulation of the quiescent accretion with the subsequent explosive phase. Results: The computed circumstellar mass distribution in the quiescent phase is highly structured with a mass enhancement in the orbital plane of about a factor of 2 as compared to the poleward directions. The simulated nova remnant evolves aspherically, propagating faster toward the poles. The shock velocities derived from the simulations agree with those derived from observations. For v_RG = 20 km s-1 and for nearly isothermal flows, we find that 10% of the mass lost by the RG is transfered to the WD. For an RG mass loss of 10-7~M? yr-1, the orbit of the system decays by 3% per million years. With the derived mass transfer rate, multi-cycle nova models provide a qualitatively correct recurrence time, amplitude, and fastness of the nova. Conclusions: Our 3D hydrodynamic simulations provide, along with the observations and nova models, the third ingredient for a deeper understanding of the recurrent novae of the RS Oph type. In combination with recent multi-cycle nova models, our results suggest that the WD in RS Oph will increase in mass. Several speculative outcomes then seem plausible. The WD may reach the Chandrasekhar limit and explode as an SN Ia. Alternatively, the mass loss of the RG could result in a smaller Roch volume, a common envelope phase, and a narrow WD + WD system. Angular momentum loss due to gravitational wave emission could trigger the merger of the two WDs and - perhaps - an SN Ia via the double degenerate scenario. In the frame of the computing project “Cosmic Engines in Galaxies”. The movie is only available in electronic form at http://www.aanda.org

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

2008-06-01

162

cnc-11 cnc-5 cnc-4 cnc-3 Cbr-R09B5.12  

E-print Network

+) and their non-transgenic siblings (Tg­) were infected with S. marcescens strain Db11 (a) or P. aeruginosa strain in uninfected conditions (OP50) and 24 h and 48 h after infection with D. coniospora (D. c.), S. marcescens (DbCherry (i-l) in uninfected worms (OP50; a,e,i) and 24 h after infection with D. coniospora (D. c.; b,f,j), S

Ewbank, Jonathan

163

Creating .DXF files from ProE (Wildfire 5.0) for use with ESPRIT CNC Software College of Engineering students and staff should be aware that ProE (Wildfire x.x) is available through the  

E-print Network

1 Creating .DXF files from ProE (Wildfire 5.0) for use with ESPRIT CNC Software College of Engineering students and staff should be aware that ProE (Wildfire x.x) is available through the CITES with older versions of ProE (Wildfire 4.0) are available upon request. Step 1. Verify that you have set

Thomas, Brian G.

164

Einstein Observatory coronal temperatures of late-type stars  

NASA Technical Reports Server (NTRS)

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.

Schmitt, J. H. M. M.; Collura, A.; Sciortino, S.; Vaiana, G. S.; Harnden, F. R., Jr.

1990-01-01

165

The friendly stars  

NASA Astrophysics Data System (ADS)

Describes prominent stars such as Vega, Arcturus, and Antares and means of identifying them, discusses the constellations in which they are located, and explains star names, stellar light, distances between stars, and types of stars.

Martin, Martha Evans

166

Energy Star  

E-print Network

ENERGY STAR ENERGY TARGETS ESL-KT-12-10-08 CATEE 2012: Clean Air Through Energy Efficiency Conference, Galveston, TX, October 9-11, 2012 POP QUIZ!!!! What is EUI?? Energy Use Intensity Do you know the EUI and any of the buildings you designed... Efficiency Conference, Galveston, TX, October 9-11, 2012 The CFLs in an ENERGY STAR qualified light fixture only need to be changed once every 8 years on average, compared with an annual ladder-climb for incandescent light bulbs. 6 CONSIDERING TIME...

Reihl, K.; Tullos, A.

2012-01-01

167

The long-period Galactic Cepheid RS Puppis - III. A geometric distance from HST polarimetric imaging of its light echoes  

E-print Network

As one of the most luminous Cepheids in the Milky Way, the 41.5-day RS Puppis is an analog of the long-period Cepheids used to measure extragalactic distances. An accurate distance to this star would therefore help anchor the zero-point of the bright end of the period-luminosity relation. But, at a distance of about 2 kpc, RS Pup is too far away for measuring a direct trigonometric parallax with a precision of a few percent with existing instrumentation. RS Pup is unique in being surrounded by a reflection nebula, whose brightness varies as pulses of light from the Cepheid propagate outwards. We present new polarimetric imaging of the nebula obtained with HST/ACS. The derived map of the degree of linear polarization pL allows us to reconstruct the three-dimensional structure of the dust distribution. To retrieve the scattering angle from the pL value, we consider two different polarization models, one based on a Milky Way dust mixture and one assuming Rayleigh scattering. Considering the derived dust distribu...

Kervella, P; Cracraft, M; Szabados, L; Breitfelder, J; Mérand, A; Sparks, W B; Gallenne, A; Bersier, D; Fouqué, P; Anderson, R I

2014-01-01

168

Restoring New Agegraphic Dark Energy in RS II Braneworld  

NASA Astrophysics Data System (ADS)

Motivated by recent works (Saridakis in Phys. Lett. B 660:138, 2008; Sheykhi in Int. J. Mod. Phys. D 19(3):305, 2010), we investigate the new agegraphic model of dark energy in the framework of RS II braneworld. We also include the case of variable gravitational constant G in our model. Moreover, we reconstruct the potential and the dynamics of the quintessence, tachyon, K-essence and dilaton scalar field models according to the evolutionary behavior of the new agegraphic dark energy model in RS II braneworld cosmology including varying G.

Jamil, Mubasher; Karami, K.; Sheykhi, A.

2011-10-01

169

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

170

"New turns from old STaRs": Enhancing the capabilities of forensic short tandem repeat analysis.  

PubMed

The field of research and development of forensic STR genotyping remains active, innovative, and focused on continuous improvements. A series of recent developments including the introduction of a sixth dye have brought expanded STR multiplex sizes while maintaining sensitivity to typical forensic DNA. New supplementary kits complimenting the core STRs have also helped improve analysis of challenging identification cases such as distant pairwise relationships in deficient pedigrees. This article gives an overview of several recent key developments in forensic STR analysis: availability of expanded core STR kits and supplementary STRs, short-amplicon mini-STRs offering practical options for highly degraded DNA, Y-STR enhancements made from the identification of rapidly mutating loci, and enhanced analysis of genetic ancestry by analyzing 32-STR profiles with a Bayesian forensic classifier originally developed for SNP population data. As well as providing scope for genotyping larger numbers of STRs optimized for forensic applications, the launch of compact next-generation sequencing systems provides considerable potential for genotyping the sizeable proportion of nucleotide variation existing in forensic STRs, which currently escapes detection with CE. PMID:24888494

Phillips, Christopher; Gelabert-Besada, Miguel; Fernandez-Formoso, Luis; García-Magariños, Manuel; Santos, Carla; Fondevila, Manuel; Ballard, David; Syndercombe Court, Denise; Carracedo, Angel; Victoria Lareu, Maria

2014-11-01

171

Star Power  

ScienceCinema

The U.S. Department of Energy's Princeton Plasma Physics Laboratory has released ''Star Power,'' a new informational video that uses dramatic and beautiful images and thought-provoking interviews to highlight the importance of the Laboratory's research into magnetic fusion.

None

2014-11-18

172

STAR Highlights  

E-print Network

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

Hiroshi Masui; for the STAR Collaboration

2011-06-29

173

Star Power  

NSDL National Science Digital Library

In this activity, learners create a star show and discover how they can prevent light pollution. Using simple materials, learners first design constellation boxes. Next, learners use their constellation boxes and desk lamps to explore how city lights impact the visibility of constellations. Finally, learners design shields to reduce light pollution and increase the visibility of constellations.

Television, Twin C.

2010-01-01

174

Distinct Role of CD86 Polymorphisms (rs1129055, rs17281995) in Risk of Cancer: Evidence from a Meta-Analysis  

PubMed Central

Background and Purpose Previous studies concerning the role of CD86 polymorphisms (rs1129055 and rs17281995) in cancer fail to provide compelling evidence. The aim of this study was to investigate the role of common polymorphisms in the risk of cancer by meta-analysis. Methods By using the search terms Cluster of Differentiation 86/CD86/B7-2/polymorphism/polymorphisms/cancer, we searched PubMed, Embase, CNKI, and Wanfang and identified four studies for rs1129055 (2137 subjects) and rs17281995 (2856 subjects) respectively. Cancer risk was estimated by odds ratio (OR) and 95% confidence interval (95% CI). Major Findings Overall, we observed significant reduced risk of cancer in relation to rs1129055. Compared with the individuals with AA genotype, the individuals with GG genotype appeared to have 62% decreased risk to develop cancer (GG versus AA: OR, 0.62; 95% CI, 0.49–0.79; Phet., 0.996). Similar effects were indicated in the G versus A allele model and the GG versus GA+AA genetic model (OR, 0.83; 95% CI, 0.74–0.93; Phet., 0.987; OR, 0.63; 95% CI, 0.50–0.79; Phet., 0.973). In addition, we found genotypes of rs17281995 had a major effect on overall cancer risk (CC versus GG: OR, 2.38; 95% CI, 1.43–3.95; Phet., 0.433; C versus G: OR, 1.23; 95% CI, 1.06–1.43; Phet., 0.521; CC versus GC+GG: OR, 2.38; 95% CI, 1.45–3.93; Phet., 0.443). The association was also observed in Caucasians and colorectal cancer. No obvious publication bias was detected in this meta-analysis. Conclusions These data reveal that rs1129055 may have protective effects on cancer risk in Asians and that rs17281995 is likely to contribute to risk of cancer, particularly colorectal cancer in Caucasians. PMID:25369324

Geng, Peiliang; Zhao, Xiaoxin; Xiang, Lisha; Liao, Yunmei; Wang, Ning; Ou, Juanjuan; Xie, Ganfeng; Liu, Chen; Li, Jianjun; Li, Hongtao; Zeng, Rui; Liang, Houjie

2014-01-01

175

Novel Oversampling Technique for Improving Signal-to-Quantization Noise Ratio on Accelerometer-Based Smart Jerk Sensors in CNC Applications.  

PubMed

Jerk monitoring, defined as the first derivative of acceleration, has become a major issue in computerized numeric controlled (CNC) machines. Several works highlight the necessity of measuring jerk in a reliable way for improving production processes. Nowadays, the computation of jerk is done by finite differences of the acceleration signal, computed at the Nyquist rate, which leads to low signal-to-quantization noise ratio (SQNR) during the estimation. The novelty of this work is the development of a smart sensor for jerk monitoring from a standard accelerometer, which has improved SQNR. The proposal is based on oversampling techniques that give a better estimation of jerk than that produced by a Nyquist-rate differentiator. Simulations and experimental results are presented to show the overall methodology performance. PMID:22412337

Rangel-Magdaleno, Jose J; Romero-Troncoso, Rene J; Osornio-Rios, Roque A; Cabal-Yepez, Eduardo

2009-01-01

176

Role of miRs in Cardiac Preconditioning  

PubMed Central

Preconditioning of the heart by sub-lethal ischemia, mild heat shock or hypoxia have evolved as powerful experimental tools to discover novel signaling mechanisms in cardioprotection. The ultimate goal is to determine novel therapeutic targets for potential application in humans in protecting the heart against ischemia-related injuries. In recent years, there has been a tremendous interest in understanding the role of small non-coding RNAs, microRNAs (miRs), in cardiovascular diseases. miRs have been recognized as regulators of gene expression by destabilization and translational inhibition of target mRNAs. Studies have shown that several miRs including miR-1, miR-133, miR-21, miR-126, miR-320, miR-92a and miR-199a are regulated after preconditioning and play an active role in protection of the heart against ischemia/reperfusion injury. These miRs also drive the synthesis of important cardioprotective proteins including HSP-70, eNOS, iNOS, HSP-20, Sirt-1 and HIF-1?. We believe that identification and targeted delivery of miR(s) in the heart could have an immense therapeutic potential in reducing myocardial infarction in patients suffering from heart disease. PMID:20980922

Salloum, Fadi N.; Yin, Chang; Kukreja, Rakesh C.

2014-01-01

177

Work in Progress: The Seven Rs of Team Building  

ERIC Educational Resources Information Center

This article argues that supportive teams--including professionals, paraprofessionals, and parents--can teach staff members how to identify and implement best practices in early intervention settings. The authors describe "the seven Rs of team building" distilled from their many years of team building and maintenance: 1) Reading cues; 2) Regular…

Brunelli, Jean; Schneider, Elaine Fogel

2004-01-01

178

An extended d(min) = 4 RS code  

NASA Technical Reports Server (NTRS)

A minimum distance d sub m - 4 extended Reed - Solomon (RS) code over GF (2 to the b power) was constructed. This code is used to correct any single byte error and simultaneously detect any double byte error. Features of the code; including fast encoding and decoding, are presented.

Deng, H.; Costello, D. J., Jr.

1983-01-01

179

Microwave observations of late-type stars with the Very Large Array  

NASA Technical Reports Server (NTRS)

The Very Large Array was used to search for microwave emission from 32 stars of late spectral type including RS CVn type stars, dwarf M stars, and stars with active chromospheres, coronae, or intense magnetic fields. The RS CVn stars were detected at 6 cm wavelength, and upper limits are established for another six. Radio emission was detected from three dwarf M flare stars, UV Cet, EQ Peg and YZ CMi. Both impulsive (no more than 20 s) and more gradual (at least ten minutes) bursts were observed from the flare star YZ CMi. Radio emission was not confirmed at 6 cm from the solar type star Chi(1) Ori, with an upper limit that is three times lower than the detections reported by other observers. Microwave emission could not be detected from any other solar type star of spectral class F to K. The quiescent radio emission from dwarf M flare stars was interpreted as nonthermal gyrosynchrotron emission by mildly relativistic electrons accelerated more or less continuously in the magnetic fields of starspots.

Pallavicini, R.; Willson, R. F.; Lang, K. R.

1985-01-01

180

Microwave observations of late-type stars with the Very Large Array  

NASA Astrophysics Data System (ADS)

The Very Large Array was used to search for microwave emission from 32 stars of late spectral type including RS CVn type stars, dwarf M stars, and stars with active chromospheres, coronae, or intense magnetic fields. The RS CVn stars were detected at 6 cm wavelength, and upper limits are established for another six. Radio emission was detected from three dwarf M flare stars, UV Cet, EQ Peg and YZ CMi. Both impulsive (no more than 20 s) and more gradual (at least ten minutes) bursts were observed from the flare star YZ CMi. Radio emission was not confirmed at 6 cm from the solar type star Chi(1) Ori, with an upper limit that is three times lower than the detections reported by other observers. Microwave emission could not be detected from any other solar type star of spectral class F to K. The quiescent radio emission from dwarf M flare stars was interpreted as nonthermal gyrosynchrotron emission by mildly relativistic electrons accelerated more or less continuously in the magnetic fields of starspots.

Pallavicini, R.; Willson, R. F.; Lang, K. R.

1985-08-01

181

Spectroscopy: Star Light, Star Bright  

NSDL National Science Digital Library

This is a student reading about the different types of spectra: continuous, absorption, and emission. Learners will read about the differences between each and see graphical representations of each. This activity is from the Stanford Solar Center's All About the Sun: Sun and Stars activity guide for Grades 5-8 and can also accompany the Stanford Solar Center's Build Your Own Spectroscope activity.

182

Star formation and the ages of stars  

NASA Astrophysics Data System (ADS)

In this contribution we illustrate how the knowledge of the ages of stars is important to constrain star formation processes. We focus on two specific cases: star formation around the supermassive black hole at the center of the Galaxy and triggered star formation on the borders of Hii regions.

Martins, F.

2014-11-01

183

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

184

Magnetic Inhibition of Convection and the Fundamental Properties of Low-mass Stars. I. Stars with a Radiative Core  

NASA Astrophysics Data System (ADS)

Magnetic fields are hypothesized to inflate the radii of low-mass stars—defined as less massive than 0.8 M ?—in detached eclipsing binaries (DEBs). We investigate this hypothesis using the recently introduced magnetic Dartmouth stellar evolution code. In particular, we focus on stars thought to have a radiative core and convective outer envelope by studying in detail three individual DEBs: UV Psc, YY Gem, and CU Cnc. Our results suggest that the stabilization of thermal convection by a magnetic field is a plausible explanation for the observed model-radius discrepancies. However, surface magnetic field strengths required by the models are significantly stronger than those estimated from observed coronal X-ray emission. Agreement between model predicted surface magnetic field strengths and those inferred from X-ray observations can be found by assuming that the magnetic field sources its energy from convection. This approach makes the transport of heat by convection less efficient and is akin to reduced convective mixing length methods used in other studies. Predictions for the metallicity and magnetic field strengths of the aforementioned systems are reported. We also develop an expression relating a reduction in the convective mixing length to a magnetic field strength in units of the equipartition value. Our results are compared with those from previous investigations to incorporate magnetic fields to explain the low-mass DEB radius inflation. Finally, we explore how the effects of magnetic fields might affect mass determinations using asteroseismic data and the implication of magnetic fields on exoplanet studies.

Feiden, Gregory A.; Chaboyer, Brian

2013-12-01

185

Christmas star.  

NASA Astrophysics Data System (ADS)

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

Bia?a, J.

186

Planck stars  

E-print Network

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

Rovelli, Carlo

2014-01-01

187

Planck stars  

E-print Network

A star that collapses gravitationally can reach a further stage of its life, where quantum-gravitational pressure counteracts weight. The duration of this stage is very short in the star proper time, yielding a bounce, but extremely long seen from the outside, because of the huge gravitational time dilation. Since the onset of quantum-gravitational effects is governed by energy density ---not by size--- the star can be much larger than planckian in this phase. The object emerging at the end of the Hawking evaporation of a black hole can then be larger than planckian by a factor $(m/m_{\\scriptscriptstyle P})^n$, where $m$ is the mass fallen into the hole, $m_{\\scriptscriptstyle P}$ is the Planck mass, and $n$ is positive. We consider arguments for $n=1/3$ and for $n=1$. There is no causality violation or faster-than-light propagation. The existence of these objects alleviates the black-hole information paradox. More interestingly, these objects could have astrophysical and cosmological interest: they produce a detectable signal, of quantum gravitational origin, around the $10^{-14} cm$ wavelength.

Carlo Rovelli; Francesca Vidotto

2014-01-25

188

The emission of the RS CVn binaries in the IRAS passbands.  

NASA Astrophysics Data System (ADS)

In the literature, there is an ambiguity pertaining to the existence of a far-IR excess in RS CVn systems. In the current paper we undertook a study of the behaviour of 103 such systems in the IRAS passbands. We found 72 acceptable detections in the 12?m band, and 40 in the 25?m band (50% more than the IRAS Point Source Catalog). Although our findings may be interpreted as indicating towards the existence of an excess beyond 12?m for some systems, the evidence is not conclusive in all but two cases. These are systems GX Lib and HR 7428, with Capella being the only system where the IRAS fluxes in all four bands originate from the stellar photosphere. Given the accuracy of the data we did not find 12?m excess for any system. We argue that the IRAS data alone cannot settle the issue, as their uncertainty is, in many cases, higher than what the Signal-to-Noise ratio of each observation implies. Furthermore, at the higher wavelength bands the IRAS angular resolution drops from 0.5' at 12?m to 2' at 100?m and the background becomes very complex, so one cannot be certain about the origin of the observed flux. The existence of IR excess in the RS CVn stars is important as far as the evolutionary scenarios for these systems are concerned. Future missions such as the Infrared Space Observatory will return more sensitive and accurate measurements and the ambiguity can be removed. The fluxes we quote will be helpful when planning these future observations, as we provide more accurate photometry and for a larger selection of sources than the IRAS Point Source Catalog.

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

1996-01-01

189

When Stars Collide  

E-print Network

When two stars collide and merge they form a new star that can stand out against the background population in a starcluster as a blue straggler. In so called collision runaways many stars can merge and may form a very massive star that eventually forms an intermediate mass blackhole. We have performed detailed evolution calculations of merger remnants from collisions between main sequence stars, both for lower mass stars and higher mass stars. These stars can be significantly brighter than ordinary stars of the same mass due to their increased helium abundance. Simplified treatments ignoring this effect give incorrect predictions for the collision product lifetime and evolution in the Hertzsprung-Russell diagram.

E. Glebbeek; O. R. Pols

2007-10-09

190

Journal editorial policies, animal welfare, and the 3Rs.  

PubMed

This study evaluates the editorial policies of a randomized sample of English language peer-reviewed journals that publish original research involving the use of animals. The aim is to identify whether journals have editorial policies relating to the use of animals in the research that they are prepared to publish and whether any policies are likely to promote animal welfare and dissemination of information on the 3Rs (reduction, refinement, replacement) within the scientific community. The results demonstrate that a significant proportion of journals publishing original research involving animals do not have any editorial policy relating to the use of animals. Of those journals that do have policies the majority simply request that the research be carried out in accordance with standard regulatory requirements. This paper aims to provide editors and publishers with the information they need to review their own editorial policies to ensure they are fulfilling their potential to promote animal welfare and dissemination of the 3Rs. PMID:20013503

Osborne, Nicola J; Payne, Daisy; Newman, Michael L

2009-12-01

191

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

NASA Technical Reports Server (NTRS)

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, George (editor)

1990-01-01

192

Triggered Star Formation by Massive Stars  

E-print Network

We present our diagnosis of the role that massive stars play in the formation of low- and intermediate-mass stars in OB associations (the Lambda Ori region, Ori OB1, and Lac OB1 associations). We find that the classical T Tauri stars and Herbig Ae/Be stars tend to line up between luminous O stars and bright-rimmed or comet-shaped clouds; the closer to a cloud the progressively younger they are. Our positional and chronological study lends support to the validity of the radiation-driven implosion mechanism, where the Lyman continuum photons from a luminous O star create expanding ionization fronts to evaporate and compress nearby clouds into bright-rimmed or comet-shaped clouds. Implosive pressure then causes dense clumps to collapse, prompting the formation of low-mass stars on the cloud surface (i.e., the bright rim) and intermediate-mass stars somewhat deeper in the cloud. These stars are a signpost of current star formation; no young stars are seen leading the ionization fronts further into the cloud. Young stars in bright-rimmed or comet-shaped clouds are likely to have been formed by triggering, which would result in an age spread of several megayears between the member stars or star groups formed in the sequence.

Hsu-Tai Lee; W. P. Chen

2005-09-13

193

Restoring New Agegraphic Dark Energy in RS II Braneworld  

Microsoft Academic Search

Motivated by recent works (Saridakis in Phys. Lett. B 660:138, 2008; Sheykhi in Int. J. Mod. Phys. D 19(3):305, 2010), we investigate the new agegraphic model of dark energy in the framework of RS II braneworld. We also include the case of\\u000a variable gravitational constant G in our model. Moreover, we reconstruct the potential and the dynamics of the quintessence,

Mubasher Jamil; K. Karami; A. Sheykhi

2011-01-01

194

Higher Curvature Effects in the ADD and RS Models  

SciTech Connect

Over the last few years several extra-dimensional models have been introduced in attempt to deal with the hierarchy problem. These models can lead to rather unique and spectacular signatures at Terascale colliders such as the LHC and ILC. The ADD and RS models, though quite distinct, have many common feature including a constant curvature bulk, localized Standard Model(SM) fields and the assumption of the validity of the EH action as a description of gravitational interactions.

Rizzo, Thomas G.; /SLAC

2006-07-05

195

Binarity and multiperiodicity in high-amplitude delta Scuti stars  

E-print Network

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 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

A. Derekas; L. L. Kiss; B. Csak; J. Griffin; C. Lindstrom; Sz. Meszaros; P. Szekely; M. C. B. Ashley; T. R. Bedding

2005-09-16

196

Metallicity and effective temperature of the secondary of RS Oph  

E-print Network

The recurrent nova RS Oph undergoes nova eruptions every ~ 10-20years as a result of thermonuclear runaway on the surface of a white dwarf close to the Chandrasekhar limit. Both the progress of the eruption, and its aftermath, depend on the (poorly known) composition of the red giant in the RS Oph system. Our aim is to understand better the effect of the giant secondary on the recurrent nova eruption. Synthetic spectra were computed for a grid of M-giant model atmospheres having a range of effective temperatures 3200 < Teff < 4400 K, gravities 0 < log g < 1 and abundances -4 <[Fe/H] < 0.5, and fit to infrared spectra of RS Oph as it returned to quiescence after its 2006 eruption. We have modelled the infrared spectrum in the range 1.4-2.5 micron to determine metallicity and effective temperature of the red giant. We find Teff = 4100 +/- 100 K, log g = 0.0 +/- 0.5, [Fe/H] = 0.0 +/- 0.5, [C/H] = -0.8 +/- 0.2, [N/H] = +0.6 +/- 0.3 in the atmosphere of the secondary, and demonstrate that that inclusion of some dust `veiling' in the spectra cannot improve our fits.

Ya. V. Pavlenko; A. Evans; T. Kerr; L. Yakovina; C. E. Woodward; D. Lynch; R. Rudy; R. L. Pearson; R. W. Russell

2008-04-21

197

Alkaline protease from Thermoactinomyces sp. RS1 mitigates industrial pollution.  

PubMed

Proteases have found a wide application in the several industrial processes, such as laundry detergents, protein recovery or solubilization, prion degradation, meat tenderizations, and in bating of hides and skins in leather industries. But the main hurdle in industrial application of proteases is their economical production on a large scale. The present investigation aimed to exploit the locally available inexpensive agricultural and household wastes for alkaline protease production using Thermoactinomyces sp. RS1 via solid-state fermentation (SSF) technique. The alkaline enzyme is potentially useful as an additive in commercial detergents to mitigate pollution load due to extensive use of caustic soda-based detergents. Thermoactinomyces sp. RS1 showed good protease production under SSF conditions of 55 °C, pH 9, and 50 % moisture content with potato peels as solid substrate. The presented findings revealed that crude alkaline protease produced by Thermoactinomyces sp. RS1 via SSF is of potential application in silver recovery from used X-ray films. PMID:24122212

Verma, Amit; Ansari, Mohammad W; Anwar, Mohmmad S; Agrawal, Ruchi; Agrawal, Sanjeev

2014-05-01

198

Radio stars; Proceedings of the Workshop on Stellar Continuum Radio Astronomy, Boulder, CO, August 8-10, 1984  

NASA Astrophysics Data System (ADS)

Papers are presented on radio-observable processes in stars, stochastic electron acceleration in stellar coronae, corotating interaction regions in stellar winds, damping of the magnetoionic Z mode, and electron-cyclotron maser emission during solar and stellar flares. Also considered are radio emission from the winds of single stars, as well as from circumstellar envelopes, AG Pegasi, L1551 IRS5, premain sequence stars and associated structures, P Cygni, Cyg OB2 No. 5, Theta(1)A Orionis, Gamma(2) Vel, symbiotic stars, and VV Cephei-type binaries. Papers are also presented on emission from flare stars and RS CVn systems, early-type stars, AM Herculis, the late-type dwarf stars UV Ceti and YZ CMi, AU Mic, dMe stars, solar-type stars, A and B stars, active late-type giants in binary systems, RS CVn binaries, W UMa Systems, and from strong X-ray sources. Also considered are parameters of the SS433 accretion disk, the confirmation of Cygnus X-3 radio periodicity, a variable Rho P Ophiuchi cloud radio star, microwave spectroscopic deduction of coronal magnetic fields, and a technique for removing confusion sources from VLA data. Other topics include stellar radio emission theoretical problems, high-angular resolution studies, and the time-resolution domain.

Hjellming, R. M.; Gibson, D. M.

199

PSR 0943+10 a bare strange star?  

E-print Network

Recent work by Rankin & Deshpande strongly suggests that there exist strong `micro-storms' rotating around the magnetic axis of the 1.1s pulsar PSR 0943+10. Such a feature hints that most probably the large-voltage vacuum gap proposed by Ruderman & Sutherland (RS) does exist in the pulsar polar cap. However, there are severe arguments against the formation of the RS-type gap in pulsars, since the binding energies of both the Fe ions and the electrons in a neutron star's surface layer is too small to prevent thermionic ejection of the particles from the surface. Here we propose that PSR 0943+10 (probably also most of the other `drifting' pulsars) might be bare strange stars rather than normal neutron stars, in which the `binding energy' at the surface is merely infinity either for the case of `pulsar' or `anti-pulsar'. It is further proposed that identifying a drifting pulsar as an anti-pulsar is the key criterion to distinguish strange stars from neutron stars.

Xu, R X; Zhang, B; Zhang, Bing

1999-01-01

200

PSR 0943+10: a bare strange star?  

E-print Network

Recent work by Rankin & Deshpande strongly suggests that there exist strong ``micro-storms'' rotating around the magnetic axis of the 1.1s pulsar PSR 0943+10. Such a feature hints that most probably the large-voltage vacuum gap proposed by Ruderman & Sutherland (RS) does exist in the pulsar polar cap. However, there are severe arguments against the formation of the RS-type gap in pulsars, since the binding energies of both the Fe ions and the electrons in a neutron star's surface layer is too small to prevent thermionic ejection of the particles from the surface. Here we propose that PSR 0943+10 (probably also most of the other ``drifting'' pulsars) might be bare strange stars rather than normal neutron stars, in which the ``binding energy'' at the surface is merely infinity either for the case of ``pulsar'' or ``anti-pulsar''. It is further proposed that identifying a drifting pulsar as an anti-pulsar is the key criterion to distinguish strange stars from neutron stars.

R. X. Xu; G. J; . Qiao; Bing Zhang

1999-07-11

201

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

202

High-Resolution N-Band Observations of the Nova RS Ophiuchi with the Keck Interferometer Nuller  

NASA Technical Reports Server (NTRS)

We report new observations of the nova RS Ophiuchi (RS Oph) using the Keck Interferometer Nulling Instrument, approximately 3.8 days following the most recent outburst that occurred on 2006 February 12. The Keck Interferometer Nuller (KIN) operates in K-band from 8 to 12.5 pm in a nulling mode, which means that the central broad-band interference fringe is a dark fringe - with an angular width of 25 mas at mid band - rather than the bright fringe used ill a conventional optical interferometer. In this mode the stellar light itself is suppressed by the destructive fringe, effectively enhancing the contrast of the circumstellar material located near the star. By subsequently shifting the neighboring bright fringe onto the center of the source brightness distribution and integrating, a second spatial regime dominated by light from the central portion of the source is almost simultaneously sampled. The nulling technique is the sparse aperture equivalent of the conventional corongraphic technique used in filled aperture telescopes. By fitting the unique KIK inner and outer spatial regime data, we have obtained an angular size of the mid-infrared continuum of 6.2, 4.0. or 5.4 mas for a disk profile, gaussian profile (fwhm), and shell profile respectively. The data show evidence of enhanced neutral atomic hydrogen emission located in the inner spatial regime relative to the outer regime. There is also evidence of a 9.7 micron silicate feature seen outside of this region. Importantly, we see spectral lines excited by the nova flash in the outer region before the blast wave reaches these regions. These lines are from neutral, weakly excited atoms which support the following interpretation. We discuss the present results in terms of a unifying model of the system that includes an increase in density in the plane of the orbit of the two stars created by a spiral shock wave caused by the motion of the stars through the cool wind of the red giant star. These data show the power and potential of the nulling technique which has been developed for the detection of Earth-like planets around nearby stars for the Terrestrial Planet Finder Mission and Darwin missions.

Barry, R. K.; Danchi, W. C.; Sokoloski, J. L.; Koresko, C.; Wisniewski, J. P.; Serabyn, E.; Traub, W.; Kuchner, M.; Greenhouse, M. A.

2007-01-01

203

The long-period Galactic Cepheid RS Puppis. III. A geometric distance from HST polarimetric imaging of its light echoes  

NASA Astrophysics Data System (ADS)

As one of the most luminous Cepheids in the Milky Way, the 41.5-day RS Puppis is an analog of the long-period Cepheids used to measure extragalactic distances. An accurate distance to this star would therefore help anchor the zero-point of the bright end of the period-luminosity relation. But, at a distance of about 2 kpc, RS Pup is too far away for measuring a direct trigonometric parallax with a precision of a few percentage points with existing instrumentation. RS Pup is unique by being surrounded by a reflection nebula whose brightness varies as pulses of light from the Cepheid propagate outward. We present new polarimetric imaging of the nebula obtained with HST/ACS. The derived map of the degree of linear polarization pL allows us to reconstruct the three-dimensional structure of the dust distribution. To retrieve the scattering angle from the pL value, we consider two different polarization models, one based on a Milky Way dust mixture and one assuming Rayleigh scattering. Considering the derived dust distribution in the nebula, we adjust a model of the phase lag of the photometric variations over selected nebular features to retrieve the distance of RS Pup. We obtain a distance of 1910 ± 80 pc (4.2%), corresponding to a parallax of ? = 0.524 ± 0.022 mas. The agreement between the two polarization models that we considered is good, but the final uncertainty is dominated by systematics in the adopted model parameters. The distance we obtain is consistent with existing measurements from the literature, but light echoes provide a distance estimate that is not subject to the same systematic uncertainties as other estimators (e.g., the Baade-Wesselink technique). RS Pup therefore provides an important fiducial for calibrating the systematic uncertainties of the long-period Cepheid distance scale. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program #13454.Table 1 and Appendix A are available in electronic form at http://www.aanda.org

Kervella, P.; Bond, H. E.; Cracraft, M.; Szabados, L.; Breitfelder, J.; Mérand, A.; Sparks, W. B.; Gallenne, A.; Bersier, D.; Fouqué, P.; Anderson, R. I.

2014-12-01

204

The Semiregular Variable Star Observing Program at Grinnell College  

NASA Astrophysics Data System (ADS)

A large body of photometric and spectroscopic data on 38 semiregular variable stars has been acquired at the Grant O. Gale Observatory of Grinnell College since 1984. This includes V and B band photoelectric photometry, CCD spectroscopic monitoring, and a large set of spectra for RS Cygni. The stars in the program were selected because they had a history of “quiescent episodes” in their pulsations that might be explained as mode switches. Time-dependent Fourier analysis has been applied to the photometric data to reveal the dominant frequency components represented in the light curves and to investigate how the strengths of those components vary - sometimes quite abruptly - over time. The spectroscopic monitoring of the entire set of stars is an ongoing project. The 413 RS Cygni spectra have been used to explore the variation of spectral features with phase. The conspicuous dip near the peak of the RS Cygni light curve does not appear to be associated with obvious variations in the strengths of spectral features.

Cadmus, Robert R.

2014-06-01

205

The Functional TP53 rs1042522 and MDM4 rs4245739 Genetic Variants Contribute to Non-Hodgkin Lymphoma Risk  

PubMed Central

As a heterogeneous kind of malignances, Non-Hodgkin lymphoma (NHL) is the most common hematologic cancer worldwide with the significantly increased morbidity in China. Accumulated evidences demonstrated that oncoprotein MDM4 plays a crucial role in the TP53 tumor suppressor signaling pathway. An rs4245739 A>C polymorphism locating in the MDM4 3?-untranslated region creates a miR-191 target site and results in allele-specific MDM4 expression. In this study, we examined the association between this polymorphism as well as the TP53 Arg72Pro (rs1042522 G>C) genetic variant and Non-Hodgkin Lymphoma (NHL) risk in a Chinese Han population. Genotypes were determined in 200 NHL cases and 400 controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by logistic regression. We found significantly increased NHL risk among carriers of the TP53 72Pro allele compared with those with the 72Arg allele (P?=?0.002 for the Pro/Pro genotype). We also observed a significantly decreased NHL risks among carriers of the MDM4 rs4245739 C allele compared with those with the A allele in Chinese (P?=?0.014 for the AC genotype). Stratified analyses revealed the associations between these SNPs and NHL risk are especially noteworthy in young or male individuals. Additionally, the associations are much pronounced in NHL patients with B-cell lymphomas or grade 3 or 4 disease. Our results indicate that the TP53 Arg72Pro and the MDM4 rs4245739 polymorphisms contribute to NHL susceptibility and support the hypothesis that genetic variants in the TP53 pathway genes can act as important modifiers of NHL risk. PMID:25203442

Fan, Chuanbo; Wei, Jinyu; Yuan, Chenglu; Wang, Xin; Jiang, Chuanwu; Zhou, Changchun; Yang, Ming

2014-01-01

206

FNDC5 (irisin) gene and exceptional longevity: a functional replication study with rs16835198 and rs726344 SNPs.  

PubMed

Irisin might play an important role in reducing the risk of obesity, insulin resistance, or several related diseases, and high irisin levels may contribute to successful aging. Thus, the irisin precursor (FNDC5) gene is a candidate to influence exceptional longevity (EL), i.e., being a centenarian. It has been recently shown that two single-nucleotide polymorphisms (SNPs) in the FNDC5 gene, rs16835198 and rs726344, are associated with in vivo insulin sensitivity in adults. We determined luciferase gene reporter activity in the two above-mentioned SNPs and studied genotype distributions among centenarians (n?=?175, 144 women) and healthy controls (n?=?347, 142 women) from Spain. We also studied an Italian [79 healthy centenarians (40 women) and 316 healthy controls (156 women)] and a Japanese cohort [742 centenarians (623 women) and 499 healthy controls (356 women)]. The rs726344 SNP had functional significance, as shown by differences in luciferase activity between the constructs of this SNP (all P???0.05), with the variant A-allele having higher luciferase activity compared with the G-allele (P?=?0.04). For the rs16835198 SNP, the variant T-allele tended to show higher luciferase activity compared with the G-allele (P?=?0.07). However, we found no differences between genotype/allele frequencies of the two SNPs in centenarians versus controls in any cohort, and no significant association (using logistic regression adjusted by sex) between the two SNPs and EL. Further research is needed with different cohorts as well as with additional variants in the FNDC5 gene or in other genes involved in irisin signaling. PMID:25427998

Sanchis-Gomar, Fabian; Garatachea, Nuria; He, Zi-Hong; Pareja-Galeano, Helios; Fuku, Noriyuki; Tian, Ye; Arai, Yasumichi; Abe, Yukiko; Murakami, Haruka; Miyachi, Motohiko; Yvert, Thomas; Santiago, Catalina; Venturini, Letizia; Fiuza-Luces, Carmen; Santos-Lozano, Alejandro; Rodríguez-Romo, Gabriel; Ricevuti, Giovanni; Hirose, Nobuyoshi; Emanuele, Enzo; Lucia, Alejandro

2014-12-01

207

Star formation - An overview  

NASA Technical Reports Server (NTRS)

Methods for studying star formation are reviewed. Stellar clusters and associations, as well as field stars, provide a fossil record of the star formation process. Regions of current star formation provide a series of snapshots of different epochs of star formation. A simplified picture of individual star formation as it was envisioned in the late 1970s is contrasted with the results of recent observations, in particular the outflow phenomenon.

Evans, N. J., II

1985-01-01

208

On stars and Steiner stars Adrian Dumitrescu  

E-print Network

On stars and Steiner stars Adrian Dumitrescu Csaba D. T´oth Guangwu Xu§ March 9, 2009 Abstract A Steiner star for a set P of n points in Rd connects an arbitrary point in Rd to all points of P, while a star connects one of the points in P to the remaining n - 1 points of P. All connections are realized

Dumitrescu, Adrian

209

STAR FORMATION HISTORIES IN A CLUSTER ENVIRONMENT AT z {approx} 0.84  

SciTech Connect

We present a spectrophotometric analysis of galaxies belonging to the dynamically young, massive cluster RX J0152.7-1357 at z {approx} 0.84, aimed at understanding the effects of the cluster environment on the star formation history (SFH) of cluster galaxies and the assembly of the red sequence (RS). We use VLT/FORS spectroscopy, ACS/WFC optical, and NTT/SofI near-IR data to characterize SFHs as a function of color, luminosity, morphology, stellar mass, and local environment from a sample of 134 spectroscopic members. In order to increase the signal-to-noise ratio, individual galaxy spectra are stacked according to these properties. Moreover, the D4000, Balmer, CN3883, Fe4383, and C4668 indices are also quantified. The SFH analysis shows that galaxies in the blue faint-end of the RS have on average younger stars ({Delta}t {approx} 2 Gyr) than those in the red bright-end. We also found, for a given luminosity range, differences in age ({Delta}t {approx} 0.5-1.3 Gyr) as a function of color, indicating that the intrinsic scatter of the RS may be due to age variations. Passive galaxies in the blue faint-end of the RS are preferentially located in the low density areas of the cluster, likely being objects entering the RS from the 'blue cloud'. It is likely that the quenching of the star formation of these RS galaxies is due to interaction with the intracluster medium. Furthermore, the SFH of galaxies in the RS as a function of stellar mass reveals signatures of 'downsizing' in the overall cluster.

Demarco, R. [Department of Astronomy, Universidad de Concepcion, Casilla 160-C, Concepcion (Chile); Gobat, R. [CEA, Laboratoire AIM, Irfu/SAp, F-91191 Gif-sur-Yvette (France); Rosati, P. [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching (Germany); Lidman, C. [Anglo-Australian Observatory, P.O. Box 296, Epping, NSW 1710 (Australia); Rettura, A. [Department of Physics and Astronomy, University of California, Riverside, 900 University Avenue, Riverside, CA 92521 (United States); Nonino, M. [INAF-OAT, via G. B. Tiepolo 11, 40131 Trieste (Italy); Van der Wel, A. [Max-Planck Institute for Astronomy, Koenigstuhl 17, D-69117, Heidelberg (Germany); Jee, M. J. [Department of Physics, University of California, Davis, One Shields Avenue, Davis, CA 95616 (United States); Blakeslee, J. P. [Herzberg Institute of Astrophysics, National Research Council of Canada, Victoria, BC V9E 2E7 (Canada); Ford, H. C. [Department of Physics and Astronomy, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Postman, M., E-mail: rdemarco@astro-udec.c [Space Telescope Science Institute, Baltimore, MD 21218 (United States)

2010-12-10

210

RS Ophiuchi in Quiescence: Why Is It X-ray Faint?  

NASA Technical Reports Server (NTRS)

The short interval between successive outbursts of RS Oph strongly suggests that it has a high mass white dwarf accreting at a high rate. This, in turn, suggests the possibility of prominent X-ray emission from RS Oph in quiescence. However, archival quiescent X-ray observations of RS Oph show it to be a modest soft X-ray source but not a strong 2-10 keV X-ray source. In this aspect, RS Oph differs markedly from T CrB. We speculate on the possible mechanisms that could significantly suppress the 2-10 keV X-ray emission in RS Oph.

Mukai, Koji

2007-01-01

211

Effects of FTO RS9939906 and MC4R RS17782313 on obesity, type 2 diabetes mellitus and blood pressure in patients with hypertension  

PubMed Central

Background Genetic variants of the FTO gene rs9939609 A/T and the MC4R gene rs17782313 C/T have been associated with obesity. Individuals with mutations in MC4R gene have lower blood pressure (BP), independently of obesity. This study aimed to investigate the association of FTO rs9939609 and MC4R rs17782313 with anthropometric indexes, BP, and type 2 diabetes mellitus among hypertensive patients. Methods We genotyped 217 individuals (86 men and 131 women) with hypertension (systolic or diastolic BP???140/90 mmHg or using antihypertensive drugs). Diabetes mellitus was diagnosed according to the American Diabetes Association criteria. Waist and neck circumferences (cm), Body Adiposity Index (BAI,%), Lipid Accumulation Product Index (LAP, cm.mmol.l) and body mass index (BMI, kg/m2) were analyzed using analysis of covariance or modified Poisson’s regression. Results Rare allele frequencies were 0.40 for A for FTO rs9939609 and 0.18 for C for MC4R rs17782313. A positive association of FTO rs9939609 and MC4R rs17782313 with BMI was observed in the overall sample. Among men and women, neck circumference was associated with the FTO genotype and, for women, MC4R genotype. In contrast, in men we found a negative association of MC4R rs17782313 with diastolic BP (TT 90.1 ±12.2, TC/CC 83.2 ±12.1; P?=?0.03) and borderline association for systolic BP after controlling for age and BMI. Conclusions Common genetic variants of FTO rs9939609 have positive associations with BMI and neck circumference and MC4R rs17782313 in women, but a negative association with diastolic and mean blood pressure in men with hypertension. PMID:23849767

2013-01-01

212

The long-period Galactic Cepheid RS Puppis. II. 3D structure and mass of the nebula from VLT/FORS polarimetry  

NASA Astrophysics Data System (ADS)

Context. The southern long-period Cepheid RS Pup is surrounded by a large circumstellar dusty nebula reflecting the light from the central star. Due to the changing luminosity of the central source, light echoes propagate into the nebula. This remarkable phenomenon was the subject of Paper I. The origin and physical properties of the nebula are however uncertain: it may have been created through mass loss from the star itself, or it could be the remnant of a pre-existing interstellar cloud. Aims: Our goal is to determine the three-dimensional structure of the light-scattering nebula, and estimate its mass. This will bring us new clues on the origin of the nebula. Knowing the geometrical shape of the nebula will also allow us to retrieve the distance of RS Pup in an unambiguous manner using a model of its light echoes (in a forthcoming work). Methods: The scattering angle of the Cepheid light in the circumstellar nebula can be recovered from its degree of linear polarization. We thus observed the nebula surrounding RS Pup using the polarimetric imaging mode of the VLT/FORS instrument, and obtained a map of the degree and position angle of linear polarization. Results: From our FORS observations, we derive a three-dimensional map of the distribution of the dust around RS Pup, whose overall geometry is an irregular and geometrically thin layer. The nebula does not present a well-defined central symmetry. Using a simple scattering model, we derive a total dust mass of Mdust = 2.9 ± 0.9 M? for the light-scattering dust within 1.8' of the Cepheid. This translates into a total mass of Mgas + dust = 290 ± 120 M?, assuming a dust-to-gas ratio of Mdust/Mgas = 1.0 ± 0.3%. Conclusions: The high mass of the dusty nebula excludes that it was created by mass-loss from the star. However, the thinness of the dust distribution is an indication that the Cepheid participated to the shaping of the nebula, e.g. through its radiation pressure or stellar wind. RS Pup therefore appears as a regular long-period Cepheid located in an exceptionally dense interstellar environment. Based on observations made with ESO telescopes at La Silla Paranal Observatory, under ESO program 383.D-0623(A).Appendix is available in electronic form at http://www.aanda.org

Kervella, P.; Mérand, A.; Szabados, L.; Sparks, W. B.; Havlen, R. J.; Bond, H. E.; Pompei, E.; Fouqué, P.; Bersier, D.; Cracraft, M.

2012-05-01

213

New insights into the dust formation of oxygen-rich AGB stars  

NASA Astrophysics Data System (ADS)

Context. Asymptotic giant branch (AGB) stars are one of the major sources of dust in the universe. The formation of molecules and dust grains and their subsequent expulsion into the interstellar medium via strong stellar winds is under intense investigation. This is in particular true for oxygen-rich stars, for which the path of dust formation has remained unclear. Aims: We conducted spatially and spectrally resolved mid-infrared multi-epoch interferometric observations to investigate the dust formation process in the extended atmospheres of oxygen-rich AGB stars. Methods: We observed the Mira variable AGB stars S Ori, GX Mon, and R Cnc between February 2006 and March 2009 with the MIDI instrument at the VLT interferometer. We compared the data to radiative transfer models of the dust shells, where the central stellar intensity profiles were described by dust-free dynamic model atmospheres. We used Al2O3 and warm silicate grains, following earlier studies in the literature. Results: Our S Ori and R Cnc data could be well described by an Al2O3 dust shell alone, and our GX Mon data by a mix of an Al2O3 and a silicate shell. The best-fit parameters for S Ori and R Cnc included photospheric angular diameters ?Phot of 9.7 ± 1.0 mas and 12.3 ± 1.0 mas, optical depths ?V(Al2O3) of 1.5 ± 0.5 and 1.35 ± 0.2, and inner radii Rin of 1.9 ± 0.3 RPhot and 2.2 ± 0.3 RPhot, respectively. Best-fit parameters for GX Mon were ?Phot = 8.7 ± 1.3 mas, ?V(Al2O3) = 1.9 ± 0.6, Rin(Al2O3) = 2.1 ± 0.3 RPhot, ?V(silicate)= 3.2 ± 0.5, and Rin(silicate)= 4.6 ± 0.2 RPhot. Our data did not show evidence of intra-cycle and cycle-to-cycle variability or of asymmetries within the error-bars and within the limits of our baseline and phase coverage. Conclusions: Our model fits constrain the chemical composition and the inner boundary radii of the dust shells, as well as the photospheric angular diameters. Our interferometric results are consistent with Al2O3 grains condensing close to the stellar surface at about 2 stellar radii, co-located with the extended atmosphere and SiO maser emission, and warm silicate grains at larger distances of about 4-5 stellar radii. We verified that the number densities of aluminum can match that of the best-fit Al2O3 dust shell near the inner dust radius in sufficiently extended atmospheres, confirming that Al2O3 grains can be seed particles for the further dust condensation. Together with literature data of the mass-loss rates, our sample is consistent with a hypothesis that stars with low mass-loss rates form primarily dust that preserves the spectral properties of Al2O3, and stars with higher mass-loss rate form dust with properties of warm silicates. Based on observations made with the Very Large Telescope Interferometer (VLTI) at the Paranal Observatory under program IDs 073.D-0711, 075.D-0097, 077.D-0630, 079.D-0172, and 082.D-0723.Tables 1-3, 8, 9 are available in electronic form at http://www.aanda.org

Karovicova, I.; Wittkowski, M.; Ohnaka, K.; Boboltz, D. A.; Fossat, E.; Scholz, M.

2013-12-01

214

Counting Your Lucky Stars  

NSDL National Science Digital Library

In this activity, learners sample a star field to estimate the number of stars in the universe. This activity simulates how astronomers use sampling instead of census (counting) to more easily collect data in space. Learners predict, count, approximate, and average the number of stars in a Star Field Sheet.

Ricles, Shannon; Hatok, Tim; Taylor, Berlina

2013-01-30

215

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

216

CPU86017-RS attenuate hypoxia-induced testicular dysfunction in mice by normalizing androgen biosynthesis genes and pro-inflammatory cytokines  

PubMed Central

Aim: Downregulation of androgen biosynthesis genes StAR (steroidogenic acute regulatory) and 3?-HSD (3?-hydroxysteroid dehydrogenase) contributes to low testosterone levels in hypoxic mice and is possibly related to increased expression of pro-inflammatory cytokines in the testis. The aim of this study is to investigate the effects of CPU86017-RS that block Ca2+ influx on hypoxia-induced testis insult in mice. Methods: Male ICR mice were divided into 5 groups: control group, hypoxia group, hypoxia group treated with nifedipine (10 mg/kg), hypoxia groups treated with CPU86017-RS (60 or 80 mg/kg). Hypoxia was induced by placing the mice in a chamber under 10%±0.5% O2 for 28 d (8 h per day). The mice were orally administered with drug in the last 14 d. At the end of experiment the testes of the mice were harvested. The mRNA and protein levels of StAR, 3?-HSD, connexin 43 (Cx43), matrix metalloprotease 9 (MMP9), endothelin receptor A (ETAR) and leptin receptor (OBRb) were analyzed using RT-PCR and Western blotting, respectively. The malondialdehyde (MDA), lactate dehydrogenase (LDH), succinate dehydrogenase (SDH) and acid phosphatase (ACP) levels were measured using biochemical kits. Serum testosterone concentration was measured with radioimmunoassay. Results: Hypoxia significantly increased the MDA level, and decreased the LDH, ACP and SDH activities in testes. Meanwhile, hypoxia induced significant downregulation of StAR and 3?-HSD in testes responsible for reduced testosterone biosynthesis. It decreased the expression of Cx43, and increased the expression of MMP9, ETAR and OBRb, leading to abnormal testis function and structure. These changes were effectively diminished by CPU86017-RS (80 mg/kg) or nifedipine (10 mg/kg). Conclusion: Low plasma testosterone level caused by hypoxia was due to downregulation of StAR and 3?-HSD genes, in association with an increased expression of pro-inflammatory cytokines. These changes can be alleviated by CPU86017-RS or nifedipine. PMID:22426698

Zhang, Guo-lin; Yu, Feng; Dai, De-zai; Cheng, Yu-si; Zhang, Can; Dai, Yin

2012-01-01

217

IntrAst2 (Petrovay) Variable stars VARIABLE STARS  

E-print Network

IntrAst2 (Petrovay) Variable stars VARIABLE STARS Definitions: (a) Stars displaying brightness variations (in the optical domain) All stars are variables (a matter of sensitivity only). (b) Stars) A variable star is what is listed in GCVS or VSX GCVS: General Catalogue of Variable Stars; http

Petrovay, Kristóf

218

Starspot Model of RS CVn Type Binary SZ PSC  

NASA Astrophysics Data System (ADS)

The emission lines of the ultraviolet region and the light curves of the optical region have been analyzed to investigate the distorted light curves of SZ Psc. The Mg II emission lines of the IUE spectra confirmed that the chromospheric activity of SZ Psc occurs on the K1 IV star. The distorted light curves in the optical region have been analyzed by the spot model where the spots are on the K1 IV star as the result of the chromospheric activity. The complete photometric solution could be deduced for SZ Psc by the good fitness with the spot model.

Kang, Young-Woon

2000-12-01

219

rs11671784 G/A and rs895819 A/G Polymorphisms Inversely Affect Gastric Cancer Susceptibility and miR-27a Expression in a Chinese Population.  

PubMed

Background rs895819 and rs11671784 are 2 SNPs in miR-27a that can influence the expression of mature miRNA. However, their role in gastric cancer development is still not well understood. This study aimed to determine whether these 2 polymorphisms are associated with gastric cancer risk in a Chinese population and how they influence the expression of miR-27a Material and Methods This was a case-control study and recruited 278 gastric cases and 278 healthy matched controls. Genotyping of these 2 SNPs among the participants were performed to assess their association with gastric cancer risk. Tumor samples from 59 patients who had physical resection were used for qRT-PCR analysis of miR-27a expression. To further valid the effects of these 2 SNPs, findings of previous studies were pooled to generate integrated evidence. Results Individuals with rs895819 G variants exhibited significantly increased risk of gastric cancer, while subjects with rs11671784 A variants had significantly reduced gastric cancer risk. Among the patients, rs895819 G variants were moderately associated with lymphatic invasion and lymph node metastasis, while rs11671784 A variants were associated with significantly reduced risk of lymphatic invasion. qRT-PCR results demonstrated rs895819 polymorphism contributed to an aberrant process from pri-miR-27a to pre-miR-27a, but rs11671784 did not affect the transcription and post-transcription processes of the miR-27a gene. The subsequent meta-analysis largely confirmed the effects of these 2 SNPs on gastric cancer risk. Conclusions rs895819 and rs11671784 inversely affect gastric cancer risk and the influence was closely related to their effects on miR-27a expression. PMID:25399405

Song, Bo; Yan, Ge; Hao, Hankun; Yang, Bei

2014-01-01

220

rs11671784 G/A and rs895819 A/G Polymorphisms Inversely Affect Gastric Cancer Susceptibility and miR-27a Expression in a Chinese Population  

PubMed Central

Background rs895819 and rs11671784 are 2 SNPs in miR-27a that can influence the expression of mature miRNA. However, their role in gastric cancer development is still not well understood. This study aimed to determine whether these 2 polymorphisms are associated with gastric cancer risk in a Chinese population and how they influence the expression of miR-27a. Material/Methods This was a case-control study and recruited 278 gastric cases and 278 healthy matched controls. Genotyping of these 2 SNPs among the participants were performed to assess their association with gastric cancer risk. Tumor samples from 59 patients who had physical resection were used for qRT-PCR analysis of miR-27a expression. To further valid the effects of these 2 SNPs, findings of previous studies were pooled to generate integrated evidence. Results Individuals with rs895819 G variants exhibited significantly increased risk of gastric cancer, while subjects with rs11671784 A variants had significantly reduced gastric cancer risk. Among the patients, rs895819 G variants were moderately associated with lymphatic invasion and lymph node metastasis, while rs11671784 A variants were associated with significantly reduced risk of lymphatic invasion. qRT-PCR results demonstrated rs895819 polymorphism contributed to an aberrant process from pri-miR-27a to pre-miR-27a, but rs11671784 did not affect the transcription and post-transcription processes of the miR-27a gene. The subsequent meta-analysis largely confirmed the effects of these 2 SNPs on gastric cancer risk. Conclusions rs895819 and rs11671784 inversely affect gastric cancer risk and the influence was closely related to their effects on miR-27a expression. PMID:25399405

Song, Bo; Yan, Ge; Hao, Hankun; Yang, Bei

2014-01-01

221

Impact of Host IL28B rs12979860, rs8099917 in Interferon Responsiveness and Advanced Liver Disease in Chronic Genotype 3 Hepatitis C Patients  

PubMed Central

Background and Aims Genetic polymorphisms near interleukin 28B gene are associated with spontaneous and treatment induced clearance of hepatitis C virus (HCV). Our objective was to evaluate the impact of interleukin 28B single nucleotide polymorphism (rs12979860, rs8099917) variability in HCV genotype 3 infected populations. Methods 400 hepatitis C seroreactive patients from different population groups in Eastern and North Eastern part of India were assessed for host and viral genotypic analysis. 83 HCV genotype 3 infected patients were administered pegylated interferon- ribavirin therapy. Viral genotyping was performed using nested reverse transcriptase-PCR followed by direct sequencing methods. Host interleukin 28B genotyping was performed using real-time PCR based single nucleotide polymorphism analysis. Results Out of 400 hepatitis C seroreactive individuals, 73.25% were found to be RNA positive. HCV genotype 3 (65.87%) was found to be the major circulating strain in this region followed by genotype 1 (32.08%). rs12979860 CC genotype was significantly associated with sustained virological response in HCV genotype 3 infected population. In patients achieving rapid virological response, favourable CC/TT allele at rs12979860, rs8099917 was found to be predominant at both the alleles at 77%, 73.2% respectively; whereas in case of patients with relapsed HCV infection CT, TG alleles were found to be predominant. Additionally, CC genotypes at rs12979860 were found to be associated with sustained virological response in patients with high viral load (OR?=?6.75, 0.05rs12979860 TT, rs8099917 GG alleles were present in 34%, 27.6% patients with relapsed HCV infection respectively. Also unfavourable CT, TG genotypes were found to be predominant in patients with advanced stages of liver disease. Conclusion CC, TT the two favourable markers at SNPs rs12979860 and rs8099917 are strongly associated with sustained virological response in genotype 3 infected populations. This information will aid clinicians to effectively design response based treatment regimen. PMID:24914551

Mukherjee, Anirban; Chaudhuri, Sujit; Chandra, Alok; Konar, Asokananda; Sadhukhan, Provash Chandra

2014-01-01

222

IFITM3 Polymorphism rs12252-C Restricts Influenza A Viruses  

PubMed Central

The IFITM3 polymorphism rs12252-C, which encodes an IFITM3 isoform (?21 IFITM3) lacking 21 amino acids at the amino terminus, has been controversially associated with poor clinical outcomes in patients with H1N1 influenza A virus (IAV) infections. In vitro studies have shown that ?21 IFITM3 loses its ability to restrict H1N1 IAV. Subsequent research has also revealed that tyrosine 20 is the key determinant for IFITM3 endocytic trafficking, which is essential for the efficient anti-viral activity of IFITM3. In contrast to previous studies, we demonstrated that both ?21 IFITM3 and an IFITM3 variant (Y20A IFITM3), in which tyrosine 20 is substituted with alanine, strongly restricted entry mediated by IAV H1, H3, H5, and H7 proteins. ?21 IFITM3 also efficiently suppressed replication of H1N1 and, to a lesser extent, H3N2 IAV. ?21 IFITM3 and Y20A IFITM3 had broader subcellular distributions than full-length IFITM3 but an abundant amount of both IFITM3 variants still localized to late endosomes and lysosomes. Our data indicate that tyrosine 20 partially regulates the subcellular localization of IFITM3 but is not functionally essential for IFITM3-mediated IAV restriction. They also suggested that mechanisms, other than viral entry restriction, might contribute to variations in clinical outcomes of H1N1 influenza associated with rs12252-C. PMID:25314048

Grotefend, Christopher Robert; Radic, Vladimir; Chung, Changik; Chung, Young-Hwa; Farzan, Michael; Huang, I-Chueh

2014-01-01

223

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

224

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

225

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. PMID:23006746

Fernandez, Lucia; Jenssen, Havard; Bains, Manjeet; Wiegand, Irith; Gooderham, W. James

2012-01-01

226

G IS ,,,, (~' G IS RS -- 210093) (~'--,,fiL...--" 210093)  

E-print Network

G IS °�,,,, � / (~'·§ G IS º RS --¿¸ø¡¡ 210093) ¡¡ (~'·§°--,,»fiL...--¿"¡¡ 210093) ¡""¡¿ ­~°¨�`¸¤`¢°--´,,l G IS ~­"-- , ¨»"·`¸¸ø--L°�,,,," , ¢�»° ^~°--´,,l G IS °�,,,, , ¨¶--»--',°l----`¸--¿ , ~´"¶­°�,,,,--·~»--' °l----`¸´¡£ ¡,,...¡¿ ´,,l¡¡ G IS¡¡°�,,,,¡¡¨

Li, Xiang

227

[Fasting hyperglycaemia and polymorphism in glucokinase promoter (rs1799884)].  

PubMed

Glucokinase is one of the most important regulators of fasting glucose levels. There are several mutations in the glucokinase gene (GCK) which are linked with monogenic diabetes. Recently, a polymorphism in its promoter has been described, which is associated with impaired fasting glucose levels. We present a 7 years and 7 months old boy with overweight and a familial background of diabetes in two previous generations. In the oral glucose tolerance test, he had impaired fasting glucose levels and after two hours, with a high insulin response. Laboratory abnormalities improved after weight loss, but he maintains a slight fasting hyperglycaemia. The molecular study of the most common monogenic diabetes forms, MODY subtypes 1, 2, and 3, was negative. The allelic variant G/A was however detected at the GCK promoter polymorphism rs1799884. PMID:21697023

Bahíllo Curieses, P; Hermoso López, F; Garrote Molpeceres, R; Zurita Muñoz, O; Campos Barros, A

2011-10-01

228

The BTB and CNC homology 1 (BACH1) target genes are involved in the oxidative stress response and in control of the cell cycle.  

PubMed

The regulation of gene expression in response to environmental signals and metabolic imbalances is a key step in maintaining cellular homeostasis. BTB and CNC homology 1 (BACH1) is a heme-binding transcription factor repressing the transcription from a subset of MAF recognition elements at low intracellular heme levels. Upon heme binding, BACH1 is released from the MAF recognition elements, resulting in increased expression of antioxidant response genes. To systematically address the gene regulatory networks involving BACH1, we combined chromatin immunoprecipitation sequencing analysis of BACH1 target genes in HEK 293 cells with knockdown of BACH1 using three independent types of small interfering RNAs followed by transcriptome profiling using microarrays. The 59 BACH1 target genes identified by chromatin immunoprecipitation sequencing were found highly enriched in genes showing expression changes after BACH1 knockdown, demonstrating the impact of BACH1 repression on transcription. In addition to known and new BACH1 targets involved in heme degradation (HMOX1, FTL, FTH1, ME1, and SLC48A1) and redox regulation (GCLC, GCLM, and SLC7A11), we also discovered BACH1 target genes affecting cell cycle and apoptosis pathways (ITPR2, CALM1, SQSTM1, TFE3, EWSR1, CDK6, BCL2L11, and MAFG) as well as subcellular transport processes (CLSTN1, PSAP, MAPT, and vault RNA). The newly identified impact of BACH1 on genes involved in neurodegenerative processes and proliferation provides an interesting basis for future dissection of BACH1-mediated gene repression in neurodegeneration and virus-induced cancerogenesis. PMID:21555518

Warnatz, Hans-Jörg; Schmidt, Dominic; Manke, Thomas; Piccini, Ilaria; Sultan, Marc; Borodina, Tatiana; Balzereit, Daniela; Wruck, Wasco; Soldatov, Alexey; Vingron, Martin; Lehrach, Hans; Yaspo, Marie-Laure

2011-07-01

229

Symbiotic stars and other H? emission-line stars towards the Galactic bulge  

NASA Astrophysics Data System (ADS)

Symbiotic stars are interacting binaries with the longest orbital periods, and their multicomponent structure makes them rich astrophysical laboratories. The accretion of a high-mass-loss-rate red giant wind on to a white dwarf (WD) makes them promising Type Ia supernova (SN Ia) progenitors. Systematic surveys for new Galactic symbiotic stars are critical to identify new promising SN Ia progenitors (e.g. RS Oph) and to better estimate the total population size to compare against SN Ia rates. Central to the latter objective is building a complete census of symbiotic stars towards the Galactic bulge. Here we report on the results of a systematic survey of H? emission-line stars covering 35 deg2. It is distinguished by the combination of deep optical spectroscopy and long-term light curves that improve the certainty of our classifications. A total of 20 bona fide symbiotic stars are found (13 S-types, 6 D-types and 1 D'-type), 35 per cent of which show the symbiotic specific Raman-scattered O VI emission bands, as well as 15 possible symbiotic stars that require further study (six S-types and nine D-types). Light curves show a diverse range of variability including stellar pulsations (semi-regular and Mira), orbital variations and slow changes due to dust. Orbital periods are determined for five S-types and Mira pulsation periods for three D-types. The most significant D-type found is H1-45 and its carbon Mira with a pulsation period of 408.6 d, corresponding to an estimated period-luminosity relation distance of ˜6.2 ± 1.4 kpc and MK = -8.06 ± 0.12 mag. If H1-45 belongs to the Galactic bulge, then it would be the first bona fide luminous carbon star to be identified in the Galactic bulge population. The lack of luminous carbon stars in the bulge is a longstanding unsolved problem. A possible explanation for H1-45 may be that the carbon enhancement was accreted from the progenitor of the WD companion. A wide variety of unusual emission-line stars were also identified. These include central stars of planetary nebulae (PNe) [one (WC10-11) Wolf-Rayet and five with high-density cores], two novae, two WN6 Wolf-Rayet stars, two possible Be stars, a B[e] star with a bipolar outflow, an ultracompact H II region and a dMe flare star. Dust obscuration events were found in two central stars of PNe, increasing the known cases to five, as well as one WN6 star. There is considerable scope to uncover several more symbiotic stars towards the bulge, many of which are currently misclassified as PNe, provided that deep spectroscopy is combined with optical and near-infrared light curves.

Miszalski, Brent; Miko?ajewska, Joanna; Udalski, Andrzej

2013-07-01

230

Single nucleotide polymorphism rs6716901 in SLC25A12 gene is associated with Asperger syndrome  

PubMed Central

Background Autism Spectrum Conditions (ASC) are a group of developmental conditions which affect communication, social interactions and behaviour. Mitochondrial oxidative dysfunction has been suggested as a mechanism of autism based on the results of multiple genetic association and expression studies. SLC25A12 is a gene encoding a calcium-binding carrier protein that localizes to the mitochondria and is involved in the exchange of aspartate for glutamate in the inner membrane of the mitochondria regulating the cytosolic redox state. rs2056202 SNP in this gene has previously been associated with ASC. SNPs rs6716901 and rs3765166 analysed in this study have not been previously explored in association with AS. Methods We genotyped three SNPs (rs2056202, rs3765166, and rs6716901) in SLC25A12 in n?=?117 individuals with Asperger syndrome (AS) and n?=?426 controls, all of Caucasian ancestry. Results rs6716901 showed significant association with AS (P?=?0.008) after correcting for multiple testing. We did not replicate the previously identified association between rs2056202 and AS in our sample. Similarly, rs3765166 (P?=?0.11) showed no significant association with AS. Conclusion The present study, in combination with previous studies, provides evidence for SLC25A12 as involved in the etiology of AS. Further cellular and molecular studies are required to elucidate the role of this gene in ASC. PMID:24679184

2014-01-01

231

Rho GTPase-Activating Protein 35 rs1052667 Polymorphism and Osteosarcoma Risk and Prognosis  

PubMed Central

The Rho GTPase-activating protein 35 (ARHGAP35), an important Rho family GTPase-activating protein, may be associated with tumorigenesis of some tumors. Here, we investigated the relationship between an important polymorphic variant at 3?-UTR of this gene (rs1052667) and osteosarcoma risk and prognosis. This hospital-based case-control study, including 247 osteosarcoma patients and 428 age-, sex-, and race-matched healthy controls, was conducted in Guangxi population. Genotypes were tested using TaqMan PCR technique. We found a significant difference in the frequency of rs1052667 genotypes between cases and controls. Compared with the homozygote of rs1052667 C alleles (rs1052667-CC), the genotypes with rs1052667 T alleles (namely, rs1052667-CT or -TT) increased osteosarcoma risk (odds ratios: 2.41 and 7.35, resp.). Moreover, rs1052667 polymorphism was correlated with such pathological features of osteosarcoma as tumor size, tumor grade, and tumor metastasis. Additionally, this polymorphism also modified the overall survival and recurrence-free survival of osteosarcoma cases. Like tumor grade, ARHGAP35 rs1052667 polymorphism was an independent prognostic factor influencing the survival of osteosarcoma. These results suggest that ARHGAP35 rs1052667 polymorphism may be associated with osteosarcoma risk and prognosis. PMID:25136583

Zhao, Jinmin; Xu, Hua; Wang, Zhe; Wu, Yang

2014-01-01

232

ESR1 rs9340799 Is Associated with Endometriosis-Related Infertility and In Vitro Fertilization Failure  

PubMed Central

Estrogen receptor alpha has a central role in human fertility by regulating estrogen action in all human reproductive tissues. Leukemia inhibitory factor (LIF) expression, a cytokine critical for blastocyst implantation, is mediated by estrogen signaling, so we hypothesized that ESR1 gene polymorphisms might be candidate risk markers for endometriosis-related infertility and in vitro fertilization (IVF) failure. We included 98 infertile women with endometriosis, 115 infertile women with at least one IVF failure and also 134 fertile women as controls. TaqMan SNP assays were used for genotyping LIF (rs929271), MDM2 (rs2279744), MDM4 (rs1563828), USP7 (rs1529916), and ESR1 (rs9340799 and rs2234693) polymorphisms. The SNP ESR1 rs9340799 was associated with endometriosis-related infertility (P < 0.001) and also with IVF failure (P = 0.018). After controlling for age, infertile women with ESR1 rs9340799 GG genotype presented 4-fold increased risk of endometriosis (OR 4.67, 95% CI 1.84–11.83, P = 0.001) and 3-fold increased risk of IVF failure (OR 3.33, 95% CI 1.38–8.03, P = 0.007). Our results demonstrate an association between ESR1 rs9340799 polymorphism and infertile women with endometriosis and also with women who were submitted to IVF procedures and had no blastocyst implantation. PMID:24427778

Paskulin, Diego Davila; Cunha-Filho, João Sabino; Paskulin, Livia Davila; Souza, Carlos Augusto Bastos; Ashton-Prolla, Patricia

2013-01-01

233

ESR1 rs9340799 is associated with endometriosis-related infertility and in vitro fertilization failure.  

PubMed

Estrogen receptor alpha has a central role in human fertility by regulating estrogen action in all human reproductive tissues. Leukemia inhibitory factor (LIF) expression, a cytokine critical for blastocyst implantation, is mediated by estrogen signaling, so we hypothesized that ESR1 gene polymorphisms might be candidate risk markers for endometriosis-related infertility and in vitro fertilization (IVF) failure. We included 98 infertile women with endometriosis, 115 infertile women with at least one IVF failure and also 134 fertile women as controls. TaqMan SNP assays were used for genotyping LIF (rs929271), MDM2 (rs2279744), MDM4 (rs1563828), USP7 (rs1529916), and ESR1 (rs9340799 and rs2234693) polymorphisms. The SNP ESR1 rs9340799 was associated with endometriosis-related infertility (P < 0.001) and also with IVF failure (P = 0.018). After controlling for age, infertile women with ESR1 rs9340799 GG genotype presented 4-fold increased risk of endometriosis (OR 4.67, 95% CI 1.84-11.83, P = 0.001) and 3-fold increased risk of IVF failure (OR 3.33, 95% CI 1.38-8.03, P = 0.007). Our results demonstrate an association between ESR1 rs9340799 polymorphism and infertile women with endometriosis and also with women who were submitted to IVF procedures and had no blastocyst implantation. PMID:24427778

Paskulin, Diego Davila; Cunha-Filho, João Sabino; Paskulin, Livia Davila; Souza, Carlos Augusto Bastos; Ashton-Prolla, Patricia

2013-01-01

234

Three new phosphoric triamides with a [C(O)NH]P(O)[N(C)(C)]2 skeleton: a database analysis of C-N-C and P-N-C bond angles.  

PubMed

In N,N,N',N'-tetraethyl-N''-(4-fluorobenzoyl)phosphoric triamide, C15H25FN3O2P, (I), and N-(2,6-difluorobenzoyl)-N',N''-bis(4-methylpiperidin-1-yl)phosphoric triamide, C19H28F2N3O2P, (II), the C-N-C angle at each tertiary N atom is significantly smaller than the two P-N-C angles. For the other new structure, N,N'-dicyclohexyl-N''-(2-fluorobenzoyl)-N,N'-dimethylphosphoric triamide, C21H33FN3O2P, (III), one C-N-C angle [117.08?(12)°] has a greater value than the related P-N-C angle [115.59?(9)°] at the same N atom. Furthermore, for most of the analogous structures with a [C(=O)NH]P(=O)[N(C)(C)]2 skeleton deposited in the Cambridge Structural Database [CSD; Allen (2002). Acta Cryst. B58, 380-388], the C-N-C angle is significantly smaller than the two P-N-C angles; exceptions were found for four structures with the N-methylcyclohexylamide substituent, similar to (III), one structure with the seven-membered cyclic amide azepan-1-yl substituent and one structure with an N-methylbenzylamide substituent. The asymmetric units of (I), (II) and (III) contain one molecule, and in the crystal structures, adjacent molecules are linked via pairs of N-H...O=P hydrogen bonds to form dimers. PMID:25279604

Pourayoubi, Mehrdad; Tarahhomi, Atekeh; Rheingold, Arnold L; Golen, James A

2014-10-15

235

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.

236

Stars in Nutrition & Cancer  

Cancer.gov

Stars in Nutrition & Cancer Soy and Cancer: Wish You Were Young Again Star Speaker Stephen Barnes, PhD Professor, Department of Pharmacology and Toxicology University of Alabama Birmingham Birmingham, Alabama Meeting Date Monday, October 04, 2010

237

Open Star Clusters  

NSDL National Science Digital Library

This site offers information about the formation of star clusters, the pleiades, how to calculate star cluster distances, and much more. There are also some great images that techers can use on this website.

2005-02-11

238

Associations between Cox-2 rs20417 and rs5275 polymorphisms and the risk of hepatocellular carcinoma: a meta analysis  

PubMed Central

Genetic polymorphisms of cyclooxygenase-2 (Cox-2) gene have been implicated in the susceptibility to hepatocellular carcinoma (HCC), but the findings from published studies are conflicting and inconclusive. To obtain a more precise estimate of the association of Cox-2 polymorphisms with HCC risk, we performed a meta-analysis of eight eligible case-control studies identified through an extensive online database search of PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure, Wanfang and Chinese Biomedicine Database; after exclusion, 2324 cases and 2604 controls were included. The pooled odds ratios with corresponding 95% confidence intervals were calculated to assess associations, using fixed- or random-effect models. In addition, subgroup analysis by ethnicity and sensitivity analysis were performed. Our results showed that the Cox-2 rs20417 (-765 G/C) polymorphism was not associated with HCC risk in the studied genetic contrast modes (C vs. G, GC vs. GG, and CC + GC vs. GG). No significant association was found with ethnic groups examined (P > 0.05). Similarly, no significant association of the Cox-2 rs5275 (+ 8473 T/C) polymorphism and HCC risk was found under any of the studied contrasts (C vs. T, TC vs. TT, CC vs. TT, CC + TC vs. TT, CC vs. TC + TT). The present meta-analysis, combining all currently available data, suggests no significant associations of either Cox-2 polymorphism with HCC risk. Further studies with a larger sample size are needed to determine the association in different ethnicities. PMID:25400773

Wu, Hexing; Wu, Xiangwei; Wan, Guoxing; Zhang, Shijie

2014-01-01

239

Dynamical Young Star Masses  

NASA Astrophysics Data System (ADS)

Mass is a star's most important property, once composition has been established, and determines the entire life trajectory of an object. Only a couple dozen young stars have absolute dynamical mass measurements, and many of those are imprecise. We propose to observe ~17 young close visual binaries in the Taurus star forming region to advance our knowledge of young star masses. We will use NIRSPEC in high-resolution mode behind the adaptive optics system on the Keck II telescope.

Prato, Lisa; Schaefer, Gail; Simon, Michal

2013-08-01

240

Association of the rs7903146 and rs12255372 polymorphisms in the TCF7L2 gene with type 2 diabetes in a population from northeastern Brazil.  

PubMed

Approximately 200 million people suffer from type 2 diabetes (T2D) worldwide, and the rapid increase in the prevalence of this disease is likely a result of multiple environmental factors, such as increased food intake and decreased physical activity in genetically predisposed individuals. Different population studies have demonstrated a strong association of two polymorphic variations in the TCF7L2 gene, the noncoding single nucleotide polymorphisms (SNPs) rs7903146 (C/T) and rs12255372 (G/T), with T2D. Herein, we analyzed the association of these SNPs with T2D in a population from northeastern Brazil. Our results showed that the genotype and allele frequencies in TCF7L2 rs7903146 and rs12255372 were similar in the patient and control groups (P > 0.05). In addition, the allele frequencies were not significantly associated with T2D risk [rs7903146: odds ratio (OR) = 0.95, 95% confidence interval (CI) = 0.52-1.76, P = 1.00, and rs12255372: OR = 1.38, 95%CI = 0.72-2.62, P = 0.41]. These data suggest that the TCF7L2 SNPs rs7903146 and rs12255372 may not significantly contribute to T2D susceptibility in this population. However, our results may reflect the small number of subjects. Alternatively, these results may be attributable to specific ethnic effects, as most of the previously reported associations were demonstrated with predominantly European populations. To reach a definitive conclusion on the role of such gene variants for T2D in mixed populations, additional efforts are necessary to replicate this study with larger populations from areas with more ethnic heterogeneity. PMID:25299103

Barros, C M A R; Araujo-Neto, A P; Lopes, T R; Barros, M A L; Motta, F J N; Canalle, R; Nunes, L C C; Rey, J A; Burbano, R R; Lima-Barros, M A; Yoshioka, F K N; Pinto, G R

2014-01-01

241

Risk of aggressive breast cancer in women of Han nationality carrying TGFB1 rs1982073 C allele and FGFR2 rs1219648 G allele in North China  

Microsoft Academic Search

The high morbidity and aggressive behavior of breast cancer are associated with genetic variations. Single nucleotide polymorphisms\\u000a (SNPs) in many genes have been demonstrated as a risk factor for breast cancer. In this study, we evaluated the association\\u000a of the SNP rs1982073 (Leu10Pro) in transforming growth factor-beta 1 (TGFB1) gene and the SNP rs1219648 in fibroblast growth factor receptor 2

Xiao-Hui Chen; Xiao-Qing Li; Ying Chen; Yu-Mei Feng

2011-01-01

242

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

243

America's Star Libraries  

ERIC Educational Resources Information Center

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

Lyons, Ray; Lance, Keith Curry

2009-01-01

244

Synergistic Epistasis of Paraoxonase 1 (rs662 and rs85460) and Apolipoprotein E4 Genes in Pathogenesis of Alzheimer's Disease and Vascular Dementia.  

PubMed

Genetic polymorphism and epistasis play a role in etiopathogenesis of Alzheimer's disease (AD) and vascular dementia (VaD). In this case-control study, a total of 241 patients were included in the study to see the effect of paraoxonase 1 (PON1; rs662 and rs85460) and apolipoprotein E (ApoE) genes in altering the odds of having AD and VaD along with serum PON and lipid profile. The presence of at least 1 variant allele of rs662, but not rs85460, increased the risk of having AD by 1.8-fold (95% confidence interval [CI]: 0.97-3.40) and VaD by 3.09-fold (95% CI: 1.4-6.9). The interaction between PON1 genes (rs662 and rs85460) and ApoE genes showed synergistic epistasis in altering the odds of significantly having both AD and VaD. On the other hand, low serum level of high-density lipoprotein and low level of serum PON activity were found associated significantly (P ? .001 in both cases) only in patients with VaD as compared to healthy control. PMID:24965284

Alam, Rizwan; Tripathi, Manjari; Mansoori, Nasim; Parveen, Shama; Luthra, Kalpana; Lakshmy, Ramakrishnan; Sharma, Subhadra; Arulselvi, Subramanian; Mukhopadhyay, Asok K

2014-12-01

245

Massive stars and star clusters in the Antennae galaxies  

E-print Network

Large numbers of young stars are formed in merging galaxies, such as the Antennae galaxies. Most of these stars are formed in compact star clusters (i.e., super star clusters), which have been the focus of a large number of studies. However, an increasing number of projects are beginning to focus on the individual stars as well. In this contribution, we examine a few results relevant to the triggering of star and star cluster formation; ask what fraction of stars form in the field rather than in clusters; and begin to explore the demographics of both the massive stars and star clusters in the Antennae.

Bradley C. Whitmore

2006-12-22

246

AFRL-IF-RS-TR-2006-89 Final Technical Report  

E-print Network

AFRL-IF-RS-TR-2006-89 Final Technical Report March 2006 SEMANTIC WEB TECHNOLOGIES FOR MOBILE nations. AFRL-IF-RS-TR-2006-89 has been reviewed and is approved for publication. APPROVED: /s/ MARK Agency AFRL/IFSB 3701 North Fairfax Drive 525 Brooks Road Arlington Virginia 22203-1714 Rome New York

Sadeh, Norman M.

247

AFRL-IF-RS-TR-2004-100 Final Technical Report  

E-print Network

AFRL-IF-RS-TR-2004-100 Final Technical Report April 2004 SCALABLE PROTECTION AGAINST DDOS AND WORM). At NTIS it will be releasable to the general public, including foreign nations. AFRL-IF-RS-TR-2004-100 has AGENCY NAME(S) AND ADDRESS(ES) Defense Advanced Research Projects Agency AFRL/IFGA 3701 North Fairfax

Park, Kihong

248

AFRL-IF-RS-TR-2006-250 Final Technical Report  

E-print Network

AFRL-IF-RS-TR-2006-250 Final Technical Report July 2006 INTEGRATION OF AUDIT DATA ANALYSIS). At NTIS it will be releasable to the general public, including foreign nations. AFRL-IF-RS-TR-2006-250 has Laboratory/IFGA 525 Brooks Rd Rome New York 13441-4505 11. SPONSORING/MONITORING AGENCY REPORT NUMBER AFRL

Noel, Steven

249

Nanostructured lipid carrier surface modified with Eudragit RS 100 and its potential ophthalmic functions  

PubMed Central

This study was carried out to evaluate the ocular performance of a cationic Eudragit (EDU) RS 100-coated nanostructured lipid carrier (NLC). The genistein encapsulated NLC (GEN-NLC) was produced using the melt-emulsification technique followed by surface absorption of EDU RS 100. The EDU RS 100 increased the surface zeta potential from ?7.46 mV to +13.60 mV, by uniformly forming a spherical coating outside the NLC surface, as shown by transmission electron microscopy images. The EDU RS 100 on the NLC surface effectively improved the NLC stability by inhibiting particle size growth. The obtained EDU RS 100-GEN-NLC showed extended precorneal clearance and a 1.22-fold increase in AUC (area under the curve) compared with the bare NLC in a Gamma scintigraphic evaluation. The EDU RS 100 modification also significantly increased corneal penetration producing a 3.3-fold increase in apparent permeability coefficients (Papp) compared with references. Draize and cytotoxicity testing confirmed that the developed EDU RS 100-GEN-NLC was nonirritant to ocular tissues and nontoxic to corneal cells. These results indicate that the NLC surface modified by EDU RS 100 significantly improves the NLC properties and exhibits many advantages for ocular use.

Zhang, Wenji; Li, Xuedong; Ye, Tiantian; Chen, Fen; Yu, Shihui; Chen, Jianting; Yang, Xinggang; Yang, Na; Zhang, Jinsong; Liu, Jinlu; Pan, Weisan; Kong, Jun

2014-01-01

250

Sandstone cementation and fluids in hydrocarbon basins R.S. Haszeldinea,*, C.I. Macaulaya  

E-print Network

-mail addresses: rsh@glg.ed.ac.uk (R.S. Haszeldine); t.fall- ick@surrc.gla.ac.uk (A.E. Fallick); gary.couplesSandstone cementation and fluids in hydrocarbon basins R.S. Haszeldinea,*, C.I. Macaulaya , A. Marchanda , M. Wilkinsona , C.M. Grahama , A. Cavanagha , A.E. Fallickb , G.D. Couplesc a Department

Haszeldine, Stuart

251

The most luminous stars.  

PubMed

Stars with individual luminosities more than a million times that of the sun are now being studied in a variety of contexts. Observational and theoretical ideas about the most luminous stars have changed greatly in the past few years. They can be observed spectroscopically even in nearby galaxies. They are not very stable; some have had violent outbursts in which large amounts of mass were lost. Because of their instabilities, these stars do not evolve to become red superglants as less luminous stars do. Theoretical scenarios for the evolution of these most massive stars depend on the effects of turbulence and mixing combined with high radition densities. PMID:17801579

Humphreys, R M; Davidson, K

1984-01-20

252

Stars and Constellations  

NSDL National Science Digital Library

This site from Jim Kaler, a Professor of Astronomy at the University of Illinois, is geared toward amateur and budding astronomers. Kaler offers detailed but non-technical descriptions of selected stars and a link to a photo of their respective constellations. Another section of the site, The Natures of Stars, consists of basic overviews of key concepts. The star descriptions are interesting to beginner and avid starwatchers alike, but the photos would benefit perhaps from superimposed arrows or other finding aids. The Stars site grows by one celestial body each week: the Star of the Week from Kaler's other site, Skylights.

Kaler, James, B.

253

Neutron Star Collision  

NSDL National Science Digital Library

Systems of orbiting neutron stars are born when the cores of two old stars collapse in supernova explosions. Neutron stars have the mass of our Sun but are the size of a city, so dense that boundaries between atoms disappear. Einsteins theory of general relativity predicts that the orbit shrinks from ripples of space-time called gravitational waves. After about 1 billion simulation years, the two neutron stars closely circle each other at 60,000 revolutions per minute. The stars finally merge in a few milliseconds, sending out a burst of gravitational waves.

Bock, Dave; Shalf, John; Swesty, Doug; Calder, Alan; Wang, Ed

1999-01-21

254

Performance Characterization of RaPToRS Systems  

NASA Astrophysics Data System (ADS)

The Rapid Pneumatic Transport of Radioactive Samples (RaPToRS) system can quickly and efficiently move radioactive materials from their activation site to a counting station. Facilities such as the NIF and LLE are considering these systems while NRL is currently using one. The system is essentially a 10 cm diameter pneumatic tube with a cylindrical sample carrier. The performance of the system depends on many factors, including the mass of the carrier, length of the tube, angle and difference in height of the tube's endpoints, the carrier's physical design, and the number, type, and distribution of blowers attached to the tube. These factors have been systematically examined to develop the fastest and most reliable system. The most significant factors are the mass and the vertical travel of the carrier. When the carrier mass is low, moving air supports the carrier in the tube, resulting in low friction. The terminal velocity ranges from 13.5 to 2.5 m/s for masses varying from 1 kg to 3 kg. Using a single 1100 W blower, the initial force exerted on the carrier was 11.3 N.

Shibata, K.; Krieger, M.; Fallica, J.; Henchen, R.; Pogozelski, E.; Padalino, S.

2011-11-01

255

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

256

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

257

Ponderable soliton stars  

NASA Astrophysics Data System (ADS)

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

Chiu, Hong-Yee

1990-12-01

258

Study on parallel and distributed management of RS data based on spatial database  

NASA Astrophysics Data System (ADS)

With the rapid development of current earth-observing technology, RS image data storage, management and information publication become a bottle-neck for its appliance and popularization. There are two prominent problems in RS image data storage and management system. First, background server hardly handle the heavy process of great capacity of RS data which stored at different nodes in a distributing environment. A tough burden has put on the background server. Second, there is no unique, standard and rational organization of Multi-sensor RS data for its storage and management. And lots of information is lost or not included at storage. Faced at the above two problems, the paper has put forward a framework for RS image data parallel and distributed management and storage system. This system aims at RS data information system based on parallel background server and a distributed data management system. Aiming at the above two goals, this paper has studied the following key techniques and elicited some revelatory conclusions. The paper has put forward a solid index of "Pyramid, Block, Layer, Epoch" according to the properties of RS image data. With the solid index mechanism, a rational organization for different resolution, different area, different band and different period of Multi-sensor RS image data is completed. In data storage, RS data is not divided into binary large objects to be stored at current relational database system, while it is reconstructed through the above solid index mechanism. A logical image database for the RS image data file is constructed. In system architecture, this paper has set up a framework based on a parallel server of several common computers. Under the framework, the background process is divided into two parts, the common WEB process and parallel process.

Chen, Yingbiao; Qian, Qinglan; Wu, Hongqiao; Liu, Shijin

2009-10-01

259

Study on parallel and distributed management of RS data based on spatial data base  

NASA Astrophysics Data System (ADS)

With the rapid development of current earth-observing technology, RS image data storage, management and information publication become a bottle-neck for its appliance and popularization. There are two prominent problems in RS image data storage and management system. First, background server hardly handle the heavy process of great capacity of RS data which stored at different nodes in a distributing environment. A tough burden has put on the background server. Second, there is no unique, standard and rational organization of Multi-sensor RS data for its storage and management. And lots of information is lost or not included at storage. Faced at the above two problems, the paper has put forward a framework for RS image data parallel and distributed management and storage system. This system aims at RS data information system based on parallel background server and a distributed data management system. Aiming at the above two goals, this paper has studied the following key techniques and elicited some revelatory conclusions. The paper has put forward a solid index of "Pyramid, Block, Layer, Epoch" according to the properties of RS image data. With the solid index mechanism, a rational organization for different resolution, different area, different band and different period of Multi-sensor RS image data is completed. In data storage, RS data is not divided into binary large objects to be stored at current relational database system, while it is reconstructed through the above solid index mechanism. A logical image database for the RS image data file is constructed. In system architecture, this paper has set up a framework based on a parallel server of several common computers. Under the framework, the background process is divided into two parts, the common WEB process and parallel process.

Chen, Yingbiao; Qian, Qinglan; Liu, Shijin

2006-12-01

260

Massive Star and Star Cluster Formation  

E-print Network

I review the status of massive star formation theories: accretion from collapsing, massive, turbulent cores; competitive accretion; and stellar collisions. I conclude the observational and theoretical evidence favors the first of these models. I then discuss: the initial conditions of star cluster formation as traced by infrared dark clouds; the cluster formation timescale; and comparison of the initial cluster mass function in different galactic environments.

Jonathan C. Tan

2006-10-16

261

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

262

Touchstone Stars: Highlights from the Cool Stars 18 Splinter Session  

E-print Network

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

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

2014-01-01

263

Association study of miR?149 rs2292832 and miR?608 rs4919510 and the risk of hepatocellular carcinoma in a large?scale population.  

PubMed

Polymorphisms in pre?microRNAs (miRNAs) or mature miRNAs may influence miRNA processing or target binding, thus contributing to tumorigenesis and cancer development. The present study aimed to evaluate whether miR?149 rs2292832 (C>T) and miR?608 rs4919510 (G>C) are associated with the risk and clinical characteristics of hepatocellular carcinoma (HCC) in a large?scale population. miR?149 rs2292832 and miR?608 rs4919510 were genotyped in a total of 993 patients with HCC and 992 unrelated healthy subjects by Sequenom MassARRAY. The results showed that, compared with the reference CC genotype, the TC+TT genotype of miR?149 was more highly associated with HCC [CC vs. TC+TT: Odds ratio (OR)=1.384, 95% confidence interval (CI)=1.013?1.892, P=0.041], and was also associated with an increased risk of hepatitis B virus (HBV)?associated HCC (CC vs. TC+TT: OR=1.453, 95% CI=1.034?2.042, P=0.031). However, no significant association between miRNA?608 rs4919510 and the risk of HCC/HBV?associated HCC was found. In addition, these two SNPs were shown not to be correlated with a range of clinical characteristics. The present study may provide an indicator for identification of the high risk of HCC in patients. PMID:25190221

Wang, Rui; Zhang, Jun; Ma, Yanyun; Chen, Linqi; Guo, Shicheng; Zhang, Xiaojiao; Ma, Yunfang; Wu, Lijun; Pei, Xiaoyu; Liu, Siran; Wang, Jiucun; Hu, Heping; Liu, Jie

2014-11-01

264

59Death Stars Our sun is an active star that  

E-print Network

- Suppose that searches for planets orbiting red dwarf stars have studied 1000 stars for a total of 480 % Problem 3 - Suppose that searches for planets orbiting red dwarf stars have studied 1000 stars for a total dwarf stars. To two significant figures, about how long would inhabitants on each planet have to wait

265

Polymorphism of the rs1800896 IL10 promoter gene protects children from post-bronchiolitis asthma.  

PubMed

Viral bronchiolitis is a major cause of hospitalization in infancy, with increased asthma risk in later childhood. However, the principal mechanisms behind post-bronchiolitic asthma have remained unclear. Previously, different cytokine polymorphisms have been associated with asthma occurrence, but no previous follow-up study has investigated cytokine polymorphisms in relation to post-bronchiolitic asthma. We hypothesized that former bronchiolitis patients with cytokine gene variants associating with Th2 cell up-regulation are at asthma risk at preschool age. Our emphasis was in IL10 rs1800896, since IL-10 has an important role in immune tolerance, and lower production of IL-10 has been associated with Th2-type immunology, and accordingly, with increased asthma risk. IL10 rs1800896, IFNG rs2430561, and IL18 rs1872387 polymorphims and their associations with asthma and allergy were studied in 135 preschool-aged children hospitalized for bronchiolitis at age 0-6 months. Parents were interviewed to record asthma and allergy from infancy to present. At age 6.4 years (mean), asthma was present in 17(12.6%), atopic eczema in 47(34.8%) and allergic rhinitis in 36(26.7%) children. IL10 rs1800896 SNP associated significantly with asthma; only 1/32 (3.1%) of those with G/G genotype had asthma (P?=?0.04). In logistic regression adjusted for gender, age and atopy, the carriage of allele A (rs1800896) was a significant risk factor for preschool asthma. IFNG rs2430561 or IL18 rs1872387 SNP's had no associations with asthma or allergy. In conclusion, IL10 rs1800896 SNP was significantly associated with preschool asthma after severe lower respiratory tract infection in early infancy. PMID:24167151

Koponen, Petri; Nuolivirta, Kirsi; Virta, Miia; Helminen, Merja; Hurme, Mikko; Korppi, Matti

2014-08-01

266

Mysterious ?6-containing nAChRs: function, pharmacology, and pathophysiology  

PubMed Central

Neuronal nicotinic acetylcholine receptors (nAChRs) are the superfamily of ligand-gated ion channels and widely expressed throughout the central and peripheral nervous systems. nAChRs play crucial roles in modulating a wide range of higher cognitive functions by mediating presynaptic, postsynaptic, and extrasynaptic signaling. Thus far, nine alpha (?2-?10) and three beta (?2, ?3, and ?4) subunits have been identified in the CNS, and these subunits assemble to form a diversity of functional nAChRs. Although ?4?2- and ?7-nAChRs are the two major functional nAChR types in the CNS, ?6*-nAChRs are abundantly expressed in the midbrain dopaminergic (DAergic) system, including mesocorticolimbic and nigrostriatal pathways, and particularly present in presynaptic nerve terminals. Recently, functional and pharmacological profiles of ?6*-nAChRs have been assessed with the use of ?6 subunit blockers such as ?-conotoxin MII and PIA, and also by using ?6 subunit knockout mice. By modulating DA release in the nucleus accumbens (NAc) and modulating GABA release onto DAergic neurons in the ventral tegmental area (VTA), ?6*-nAChRs may play important roles in the mediation of nicotine reward and addiction. Furthermore, ?6*-nAChRs in the nigrostriatal DAergic system may be promising targets for selective preventative treatment of Parkinson's disease (PD). Thus, ?6*-nAChRs may hold promise for future clinical treatment of human disorders, such as nicotine addiction and PD. In this review, we mainly focus on the recent advances in the understanding of ?6*-nAChR function, pharmacology and pathophysiology. PMID:19498417

Yang, Ke-chun; Jin, Guo-zhang; Wu, Jie

2009-01-01

267

The CHRNA3 rs578776 Variant is Associated with an Intrinsic Reward Sensitivity Deficit in Smokers  

PubMed Central

A compromised brain reward system has been postulated as a key feature of drug dependence. We examined whether several polymorphisms of genes found to regulate nicotinic acetylcholine receptor (nAChR) and dopamine expression were related to an intrinsic reward sensitivity (IRS) deficit we previously identified among a subgroup of smokers using event-related potentials (ERPs). We examined genetic polymorphisms within the CHRNA5-A3-B4 gene cluster (CHRNA3 rs578776, CHRNA5 rs16969968, LOC123688 rs8034191, and CHRNA3 rs1051730), the ANKK1 gene (rs1800497), and the D2 dopamine receptor gene (DRD2 rs1079597, DRD2 rs1799732) from 104 smokers of European ancestry in a smoking cessation trial. Prior to treatment, we recorded ERPs evoked by emotional (both pleasant and unpleasant), neutral, and cigarette-related pictures. Smokers were assigned to two groups (IRS+/IRS?) based on the amplitude of the late positive potential (LPP) component to the pictures, a neural marker of motivational salience. Smokers (n?=?42) with blunted brain responses to intrinsically rewarding (pleasant) pictures and enhanced responses to cigarette pictures were assigned to the IRS? group, while smokers (n?=?62) with the opposite pattern of LPP responding were assigned to the IRS+ group. Carriers of the protective minor T allele (T/T, C/T) of the CHRNA3 rs578776 were less likely to be members of the IRS? group than those homozygous for the at-risk C allele (C/C). The CHRNA3 rs578776 polymorphism did not differ on questionnaires of nicotine dependence, depressed mood, or trait affective disposition and did not predict abstinence at 6?months after the quit date. These results suggest that polymorphisms of genes influencing nAChR expression are related to an endophenotype of reward sensitivity in smokers. PMID:24065931

Robinson, Jason D.; Versace, Francesco; Lam, Cho Y.; Minnix, Jennifer A.; Engelmann, Jeffrey M.; Cui, Yong; Karam-Hage, Maher; Shete, Sanjay S.; Tomlinson, Gail E.; Chen, Tina T.-L.; Wetter, David W.; Green, Charles E.; Cinciripini, Paul M.

2013-01-01

268

Massive Star Generations  

NASA Astrophysics Data System (ADS)

This survey extends and enhances Chandra/ACIS studies of massive stars by sampling both very young O stars ionizing ultracompact HII regions (UCHIIRs) and the aged and evolved massive stars in Young Massive Clusters (YMCs). This will double the Chandra sample of UCHIIRs and provide dozens of X-ray spectra on older massive stars. We combine two new ACIS-I pointings with GTO and archival data to achieve an economical study of W42 and W33, nearby massive star-forming regions <1 Myr old, plus the much older and more distant YMCs Cl 1813-178 and Red Supergiant Cluster 1. These sensitive observations will also document pre-main sequence populations and trace the effects of massive star feedback by mapping diffuse X-rays from supernova remnants and wind-shocked plasma.

Townsley, Leisa

2014-09-01

269

Intelligent star tracker  

NASA Astrophysics Data System (ADS)

Current state-of-the-art commercial star sensors typically weigh 15 pounds, attain 5 to 10 arc-second accuracy, and use roughly 10 watts of power. Unfortunately, the current state-of-the-art commercial star sensors do not meet many of NASA's next-generation spacecraft and instrument needs. Nor do they satisfy Air Force's needs for micro/nano-satellite systems. In an effort to satisfy micro/nano satellite mission needs the Air Force Research Laboratory is developing an intelligent star Tracker, called IntelliStar, which incorporates several novel technologies including Silicon carbide optical housing, MEMs based adaptive optic technologies, smart active pixels, and algebraic coding theory. The design considerations associated with the development of the IntelliStar system are presented along with experimental results which characterize each technologies contribution to overall system performance. In addition to being light weight, the IntelliStar System offers advantages in speed, size, power consumption, and radiation tolerance.

Clark, Natalie

2001-11-01

270

Human Resources rs_msc30 Page 1 of 10 Date issued: 28-Sep-12 Human Resources  

E-print Network

;Human Resources ­ rs_msc30 Page 5 of 10 Date issued: 28-Sep-12 Human Resources: Recruitment & SelectionHuman Resources ­ rs_msc30 Page 1 of 10 Date issued: 28-Sep-12 Human Resources Apply for Visa;Human Resources ­ rs_msc30 Page 2 of 10 Date issued: 28-Sep-12 Map 2 * #12;Human Resources ­ rs_msc30

Hickman, Mark

271

RS-34 (Peacekeeper Post Boost Propulsion System) Orbital Debris Application Concept Study  

NASA Technical Reports Server (NTRS)

The Advanced Concepts Office (ACO) at the NASA Marshall Space Flight Center (MSFC) lead a study to evaluate the Rocketdyne produced RS-34 propulsion system as it applies to an orbital debris removal design reference mission. The existing RS-34 propulsion system is a remaining asset from the de-commissioned United States Air Force Peacekeeper ICBM program; specifically the pressure-fed storable bi-propellant Stage IV Post Boost Propulsion System. MSFC gained experience with the RS-34 propulsion system on the successful Ares I-X flight test program flown in the Ares I-X Roll control system (RoCS). The heritage hardware proved extremely robust and reliable and sparked interest for further utilization on other potential in-space applications. Subsequently, MSFC is working closely with the USAF to obtain all the remaining RS-34 stages for re-use opportunities. Prior to pursuit of securing the hardware, MSFC commissioned the Advanced Concepts Office to understand the capability and potential applications for the RS-34 Phoenix stage as it benefits NASA, DoD, and commercial industry. Originally designed, the RS-34 Phoenix provided in-space six-degrees-of freedom operational maneuvering to deploy multiple payloads at various orbital locations. The RS-34 Concept Study, preceded by a utilization study to understand how the unique capabilities of the RS-34 Phoenix and its application to six candidate missions, sought to further understand application for an orbital debris design reference mission as the orbital debris removal mission was found to closely mimic the heritage RS-34 mission. The RS-34 Orbital Debris Application Concept Study sought to identify multiple configurations varying the degree of modification to trade for dry mass optimization and propellant load for overall capability and evaluation of several candidate missions. The results of the RS-34 Phoenix Utilization Study show that the system is technically sufficient to successfully support all of the missions analyzed. The results and benefits of the RS-34 Orbital Debris Application Concept Study are presented in this paper.

Esther, Elizabeth A.; Burnside, Christopher G.

2013-01-01

272

The Theatre of stars  

NASA Astrophysics Data System (ADS)

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

Cavedon, M.; Peri, F.

273

Sizing up the stars  

NASA Astrophysics Data System (ADS)

For the main part of this dissertation, I have executed a survey of nearby, main sequence A, F, and G-type stars with the CHARA Array, successfully measuring the angular diameters of forty-four stars to better than 4% accuracy. The results of these observations also yield empirical determinations of stellar linear radii and effective temperatures for the stars observed. In addition, these CHARA-determined temperatures, radii, and luminosities are fit to Yonsei-Yale isochrones to constrain the masses and ages of the stars. These quantities are compared to the results found in Allende Prieto & Lambert (1999), Holmberg et al. (2007), and Takeda (2007), who indirectly determine these same properties by fitting models to observed photometry. I find that for most cases, the models underestimate the radius of the star by ~ 12%, while in turn they overestimate the effective temperature by ~ 1.5-4%, when compared to my directly measured values, with no apparent correlation to the star's metallicity or color index. These overestimated temperatures and underestimated radii in these works appear to cause an additional offset in the star's surface gravity measurements, which consequently yield higher masses and younger ages, in particular for stars with masses greater than ~ 1.3 [Special characters omitted.] . Alternatively, these quantities I measure are also compared to direct measurements from a large sample of eclipsing binary stars in Andersen (1991), and excellent agreement is seen within both data sets. Finally, a multi-parameter solution is found to fit color-temperature-metallicity values of the stars in this sample to provide a new calibration of the effective temperature scale for these types of stars. Published work in the field of stellar interferometry and optical spectroscopy of early-type stars are presented in Appendix D and E, respectively. INDEX WORDS: Interferometry, Infrared, Stellar Astronomy, Fundamental Properties, Effective Temperatures, Stellar Radii

Boyajian, Tabetha S.

274

More lead stars  

NASA Astrophysics Data System (ADS)

The standard model for the operation of the s-process in asymptotic giant branch (AGB) stars predicts that low-metallicity ([Fe/H] <~ -1) AGB stars should exhibit large overabundances of Pb and Bi as compared to other s-elements. The discovery of the first three such ``lead stars'' (defined as stars enriched in s-elements with [Pb/hs] >~ 1, hs being any of Ba, La or Ce) among CH stars has been reported in a previous paper (Van Eck et al. \\cite{VanEck-01}). Five more CH stars (with [Fe/H] ranging from -1.5 to -2.5) are studied in the present paper, and two of them appear to be enriched in lead (with [Pb/Ce] =~ 0.7). The Pb I line at lambda4057 .812 Å is detected and clearly resolved thanks to high-resolution spectra (R = lambda /Delta lambda = 135ts000 ). The abundances for these two stars (HD 198269 and HD 201626) are consistent with the predictions for the s-process operating in low-metallicity AGB stars as a consequence of the ``partial mixing'' of protons below the convective hydrogen envelope. Another two stars (HD 189711 and V Ari) add to a growing number of low-metallicity stars (also including LP 625-44 and LP 706-7, as reported by Aoki et al. \\cite{Aoki2001}) which do not conform to these predictions. Variations on the canonical proton-mixing scenario for the operation of the s-process in low-metallicity stars, that could account for these discrepant stars, are briefly discussed. Based on observations carried out at the European Southern Observatory (La Silla, Chile; Program 65.L-0354) and at the Observatoire de Haute Provence (operated by CNRS, France).

Van Eck, S.; Goriely, S.; Jorissen, A.; Plez, B.

2003-06-01

275

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

276

Orbiting Binary Stars  

NSDL National Science Digital Library

This simulation demonstrates the path of binary stars' orbit. The user is able to set the masses, orbital separation, orbital eccentricity, the inclination angle to our line of sight, and the angle of the nodes of two orbiting stars. The observed velocities of the two stars, and the Doppler shifted spectral lines are also shown in the upper right box. The site also includes definitions of terms used, instructions on how to use the simulation and a few examples.

Kolena, John

2007-12-11

277

Star Market Scandal  

NSDL National Science Digital Library

The is one several activities in which students are required to access and analyze actual data from NASA missions, including video interviews with real NASA scientists, to solve a mystery. In this mystery, students explore stars and their properties, investigate the different characteristics of stars, and look for trends and patterns to determine what kinds of stars different companies are buying, and why. During the activity, students analyze a list of stars purchased by each company using tools showing a star's luminosity in infrared, x-ray, and visible ranges of light, and tools that plot the stars in different ways. Star Market can be used as a supplemental learning tool to support the scientific method, understanding the life cycle of stars, and learning about the different reasons scientists study stars. It is one several activities within "Space Mysteries," a series of inquiry-driven, interactive Web explorations. Each Mystery in "Space Mysteries" is designed to teach at least one physical science concept (e.g. interactions of energy and matter, structures and properties of matter, energy, motion, or forces), and is accompanied by materials to be used by classroom teachers.

278

Massive soliton stars  

NASA Astrophysics Data System (ADS)

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

Chiu, Hong-Yee

1990-05-01

279

Massive soliton stars  

NASA Technical Reports Server (NTRS)

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

Chiu, Hong-Yee

1990-01-01

280

Sixquarks in neutron stars  

NASA Astrophysics Data System (ADS)

Neutron star parameters are calculated with regard to the existence of recently discovered sixquarks-narrow dibaryon resonances. It is shown that as compared to the previous calculations, the maximum masses and radii of neutron stars are notably reduced, compact objects of very low masses appear to be stable. It is shown that at the certain stage of the star collapse an instability occurs which leads to the second type Supernova flare. It is also shown that in a certain pressure interval two phases exist: neutron and neutron-sixquark ones, and the first type Supernova flares can be interpreted as a phase transition in the external layers of the neutron stars.

Kuzmin, Yu. V.

281

Combinations of 148 navigation stars and the star tracker  

NASA Technical Reports Server (NTRS)

The angular separation of all star combinations for 148 nav star on the onboard software for space transportation system-3 flight and following missions is presented as well as the separation of each pair that satisfies the viewing constraints of using both star trackers simultaneously. Tables show (1) shuttle star catalog 1980 star position in M 1950 coordinates; (2) two star combination of 148 nav stars; and (3) summary of two star-combinations of the star tracker 5 deg filter. These 148 stars present 10,875 combinations. For the star tracker filters of plus or minus 5 deg, there are 875 combinations. Formalhaut (nav star 26) has the best number of combinations, which is 33.

Duncan, R.

1980-01-01

282

Star-ND (Multi-Dimensional Star-Identification)  

E-print Network

In order to perform star-identification with lower processing requirements, multi-dimensional techniques are implemented in this research as a database search as well as to create star pattern parameters. New star pattern parameters are presented...

Spratling, Benjamin

2012-07-16

283

Horizontal Branch stars as AmFm/HgMn stars  

E-print Network

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

G. Michaud; J. Richer

2008-02-12

284

Influence of hydroxyethylcellulose on the drug release properties of theophylline pellets coated with Eudragit ® RS 30 D  

Microsoft Academic Search

The objective of this study was to investigate the influence of a hydrophilic polymer, hydroxyethylcellulose (HEC), on the release properties of theophylline from pellets coated with Eudragit® RS 30 D, and the physicochemical properties of Eudragit® RS 30 D cast films. The release rate of theophylline from Eudragit® RS 30 D coated pellets decreased during storage at 25°C\\/60% RH due

Weijia Zheng; Dorothea Sauer; James W. McGinity

2005-01-01

285

78 FR 20386 - Notice of Receipt of Petition for Decision That Nonconforming 2012 Porsche GT3RS Passenger Cars...  

Federal Register 2010, 2011, 2012, 2013

...Nonconforming 2012 Porsche GT3RS Passenger Cars Are Eligible for Importation AGENCY: National...nonconforming 2012 Porsche GT3RS passenger cars that were not originally manufactured to...nonconforming 2012 Porsche GT3RS passenger cars are eligible for importation into the...

2013-04-04

286

RS4002Myth|2014-2015 SCHOOL OF DIVINITY, HISTORY AND PHILOSOPHY ACADEMIC SESSION 2014-2015  

E-print Network

1 RS4002Myth|2014-2015 SCHOOL OF DIVINITY, HISTORY AND PHILOSOPHY ACADEMIC SESSION 2014-2015 RS4002: Myth 30 Credits: 11 weeks PLEASE NOTE CAREFULLY: The full set of school regulations and procedures 01224 272366 divrs@abdn.ac.uk #12;2 RS4002Myth|2014-2015 TIMETABLE One one-hour class and one two

Levi, Ran

287

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

288

Identifying Young, Nearby Stars  

NASA Technical Reports Server (NTRS)

Young stars have certain characteristics, e.g., high atmospheric abundance of lithium and chromospheric activity, fast rotation, distinctive space motion and strong X-ray flux compared to that of older main sequence stars. We have selected a list of candidate young (<100Myr) and nearby (<60pc) stars based on their space motion and/or strong X-ray flux. To determine space motion of a star, one needs to know its coordinates (RA, DEC), proper motion, distance, and radial velocity. The Hipparcos and Tycho catalogues provide all this information except radial velocities. We anticipate eventually searching approx. 1000 nearby stars for signs of extreme youth. Future studies of the young stars so identified will help clarify the formation of planetary systems for times between 10 and 100 million years. Certainly, the final output of this study will be a very useful resource, especially for adaptive optics and space based searches for Jupiter-mass planets and dusty proto-planetary disks. We have begun spectroscopic observations in January, 2001 with the 2.3 m telescope at Siding Spring Observatory (SSO) in New South Wales, Australia. These spectra will be used to determine radial velocities and other youth indicators such as Li 6708A absorption strength and Hydrogen Balmer line intensity. Additional observations of southern hemisphere stars from SSO are scheduled in April and northern hemisphere observations will take place in May and July at the Lick Observatory of the University of California. AT SSO, to date, we have observed about 100 stars with a high resolution spectrometer (echelle) and about 50 stars with a medium spectral resolution spectrometer (the "DBS"). About 20% of these stars turn out to be young stars. Among these, two especially noteworthy stars appear to be the closest T-Tauri stars ever identified. Interestingly, these stars share the same space motions as that of a very famous star with a dusty circumstellar disk--beta Pictoris. This new finding better constrains the age of beta Pictoris to be approx. 10 Myr.

Webb, Rich; Song, Inseok; Zuckerman, Ben; Bessell, Mike

2001-01-01

289

GLOBAL STAR FORMATION REVISITED  

SciTech Connect

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 [Physics Department, University of Oxford, 1 Keble Road, Oxford OX1 3RH (United Kingdom); Norman, Colin [Physics Department, Johns Hopkins University, 2400 North Charles Street, Baltimore, MD 21218 (United States)], E-mail: silk@astro.ox.ac.uk, E-mail: norman@stsci.edu

2009-07-20

290

Neutron Star Compared to Manhattan  

NASA Video Gallery

A pulsar is a neutron star, the crushed core of a star that has exploded. Neutron stars crush half a million times more mass than Earth into a sphere no larger than Manhattan, as animated in this s...

291

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

292

The threat of information theft by reception of electromagnetic radiation from RS232 cables  

Microsoft Academic Search

This report gives the results of theseexperiments and research into the underlyingmechanisms. These results show, that comparedwith the VDU case, RS-232 eavesdropping hassignificantly different consequences with regardto information security.

Peter Smulders

1990-01-01

293

Stars and Flowers, Flowers and Stars  

NASA Astrophysics Data System (ADS)

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

Minti, Hari

2012-12-01

294

Spectral Modeling Hot Star Winds  

E-print Network

Spectral Modeling of X-Rays from Hot Star Winds Emma Wollman Advisor: David Cohen #12;Hot Stars Massive Stars Early-type Stars HD 93129 A (O3) M = 94.8 M! L = 1.5e6 L! T = 7.4 T! R = 22.5 R! ·· Produce supernovaeProduce supernovae (neutron stars, black holes)(neutron stars, black holes) ·· Found near birth

Cohen, David

295

Compressive Creep Response of T1000G\\/RS14 Graphite\\/Polycyanate Composite Materials  

Microsoft Academic Search

The response of a T1000G\\/RS-14 graphite\\/polycyanate composite material system to transverse compressive loads is quantified via experimentation. The primary objective of the work was to quantify the effects of process environment and test environment on the T1000G\\/RS-14 compressive creep response. Tests were conducted on both the neat resin and the composite material system. In addition to the creep tests, static

Starbuck

1998-01-01

296

A Reed-Solomon Product-Code (RS-PC) decoder for DVD applications  

Microsoft Academic Search

The digital versatile disk (DVD), an emerging standard of optical storage, provides a higher capacity than audio CD, CD-ROM or video CD (VCD). To mitigate the errors introduced during manufacturing or by user damage, a Reed-Solomon Product-Code (RS-PC) is used in DVD for error correction. For this application, the authors present an RS-PC decoder chip with a dual-frame-buffer architecture. The

H. C. Chang; C. Shung

1998-01-01

297

Polymorphism of rs873308 near the transmembrane protein 57 gene is associated with serum lipid levels  

PubMed Central

SNP (single-nucleotide polymorphism) of rs10903129 near the TMEM (transmembrane protein) 57 locus has been associated with TC (total cholesterol) in a previous GWAS (genome-wide association study), but the association of TMEM57 rs873308 SNP and serum lipid levels has not been previously reported. The current study was undertaken to detect the association of the TMEM57 rs873308 SNP and several environmental factors with serum lipid profiles in the Han Chinese and Mulao populations. The genotypes of the TMEM57 rs873308 SNP in 865 individuals of Han Chinese and 902 participants of Mulao nationality were determined by PCR and RFLP (restriction-fragment-length polymorphism) combined with gel electrophoresis and then confirmed by direct sequencing. The T allele frequency of TMEM57 rs873308 SNP was not different between Han and Mulao (23.18% versus 25.72%, P>0.05), but different between males and females in the two ethnic groups (P<0.05). The T allele carriers had lower serum TC, Apo (apolipoprotein) B, HDL-C (high-density lipoprotein cholesterol) levels, ApoA1/ApoB ratio in Han; and lower TAG (triacylglycerol), LDL-C (low-density lipoprotein cholesterol), ApoA1 levels and the ApoA1/ApoB ratio and higher HDL-C levels in Mulao than the T allele non-carriers. There was also different association of the TMEM57 rs873308 SNP and serum lipid profiles between males and females in the both ethnic groups. Serum lipid parameters in the two ethnic groups were also associated with several environmental factors. The association of the TMEM57 rs873308 SNP and serum lipid levels was different in the Han Chinese and Mulao populations and between males and females in the both ethnic groups. There may be a sex-specific association of the TMEM57 rs873308 SNP and serum lipid levels in our study populations. PMID:24517463

Guo, Tao; Yin, Rui-Xing; Lin, Quan-Zhen; Wu, Jian; Shen, Shao-Wen; Sun, Jia-Qi; Shi, Guang-Yuan; Wu, Jin-Zhen; Li, Hui; Wang, Yi-Ming

2014-01-01

298

Ribonuclease Rs from Rhizopus stolonifer: lowering of optimum temperature in the presence of urea  

Microsoft Academic Search

RNase Rs showed an approx. 2-fold increase in its activity when incubated in the presence of 2 M urea at 37°C. The increase in its activity, in the presence of urea, was comparable to the activity at its optimum temperature, i.e. 45°C. Compared to the native enzyme at 37°C, the Km and Vmax of RNase Rs at 45°C and in

Rajashree A Deshpande; Ameeta R Kumar; M. Islam Khan; Vepatu Shankar

2001-01-01

299

Survey of Canadian Animal-Based Researchers' Views on the Three Rs: Replacement, Reduction and Refinement  

PubMed Central

The ‘Three Rs’ tenet (replacement, reduction, refinement) is a widely accepted cornerstone of Canadian and international policies on animal-based science. The Canadian Council on Animal Care (CCAC) initiated this web-based survey to obtain greater understanding of ‘principal investigators’ and ‘other researchers’ (i.e. graduate students, post-doctoral researchers etc.) views on the Three Rs, and to identify obstacles and opportunities for continued implementation of the Three Rs in Canada. Responses from 414 participants indicate that researchers currently do not view the goal of replacement as achievable. Researchers prefer to use enough animals to ensure quality data is obtained rather than using the minimum and potentially waste those animals if a problem occurs during the study. Many feel that they already reduce animal numbers as much as possible and have concerns that further reduction may compromise research. Most participants were ambivalent about re-use, but expressed concern that the practice could compromise experimental outcomes. In considering refinement, many researchers feel there are situations where animals should not receive pain relieving drugs because it may compromise scientific outcomes, although there was strong support for the Three Rs strategy of conducting animal welfare-related pilot studies, which were viewed as useful for both animal welfare and experimental design. Participants were not opposed to being offered “assistance” to implement the Three Rs, so long as the input is provided in a collegial manner, and from individuals who are perceived as experts. It may be useful for animal use policymakers to consider what steps are needed to make replacement a more feasible goal. In addition, initiatives that offer researchers greater practical and logistical support with Three Rs implementation may be useful. Encouragement and financial support for Three Rs initiatives may result in valuable contributions to Three Rs knowledge and improve welfare for animals used in science. PMID:21857928

Fenwick, Nicole; Danielson, Peter; Griffin, Gilly

2011-01-01

300

TCL\\/TK BASED API FOR OMRON'S RS485 INTERFACE NETWORK  

Microsoft Academic Search

This paper describes one application of the script language Tcl\\/Tk for building of OMRON'S RS485 interface networking API (Application Program Interface). In the article are considered several topics: OMRON'S RS485 interface specification, networks realization using this interface,Omron application commands set, building of API as TCL\\/TK extension for Win95\\/98\\/NT and Tcl\\/Tk technique using for API realization. It's present the data base

A. Boneva; R. Krasteva

301

Isolation and characterization of the murine X-linked juvenile retinoschisis ( Rs1h ) gene  

Microsoft Academic Search

.   X-linked juvenile retinoschisis (RS) is a vitreoretinal degeneration affecting only males. Recently, the RS1 gene underlying\\u000a this common cause of early vision loss was identified and shown to encode a 224-amino acid precursor protein including a 23-residue\\u000a leader sequence as well as a highly conserved discoidin motif at the C-terminus. Functional studies in other proteins with\\u000a discoidin motifs have

Andrea E. Gehrig; Regina Warneke-Wittstock; Christian G. Sauer; Bernhard H. F. Weber

1999-01-01

302

A suite of RS/1 procedures for chemical laboratory statistical quality control and Shewhart control charting  

SciTech Connect

A suite of RS/1 procedures for Shewhart control charting in chemical laboratories is described. The suite uses the RS series product QCA (Quality Control Analysis) for chart construction and analysis. The suite prompts users for data in a user friendly fashion and adds the data to or creates the control charts. All activities are time stamped. Facilities for generating monthly or contiguous time segment summary charts are included. The suite is currently in use at Westinghouse Savannah River Company.

Shanahan, K.L.

1990-09-01

303

An iterative decoding technique and architecture for RS concatenated TCM coding systems  

Microsoft Academic Search

In this paper, we propose a soft value modification (SVM) algorithm, based on which we further propose a new low-complexity iterative decoding technique for the conventional serial concatenated coding system which consists of Reed-Solomon (RS) code and Trellis coded Modulation (TCM) scheme with an interleaver in between. In our decoding technique, the RS decoder is based on Berlekamp-Massey (BM) algorithm,

Lin Gui; Yin Xu; Bo Liu; Liang Gong; Ying Li

2010-01-01

304

~Green Beans ~ Coastal Star  

E-print Network

~Onions ~Green Beans ~Peppers #12;4/13/2011 6 #12;4/13/2011 7 #12;4/13/2011 8 ~ Coastal Star F Si From Siegers... ~Green Towers "Consistent performance in all growing regions" ~Musena "Requires heat heads needed for our CSA. We will start with Cherokee and Magenta, followed by Green Star

Netoff, Theoden

305

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

306

Science through ARts (STAR)  

ERIC Educational Resources Information Center

Science Through ARts (STAR) is a free, international, cross-curricular program thematically aligned with "The Vision for Space Exploration," a framework of goals and objectives published by NASA in February 2004. Through the STAR program, students in grades 5 through 12 are encouraged to apply their knowledge in creative ways as they approach a…

Densmore, Marycay; Kolecki, Joseph C.; Miller, Allan; Petersen, Ruth; Terrell, Mike

2005-01-01

307

Rotating hybrid compact stars  

NASA Astrophysics Data System (ADS)

Starting from equations of state of nucleonic and color-superconducting quark matter and assuming a first-order phase transition between these, we construct an equation of state of stellar matter, which contains three phases: a nucleonic phase, as well as two-flavor and three-flavor color-superconducting phases of quarks. Static sequences of the corresponding hybrid stars include massive members with masses of ~2 M? and radii in the range of 13 ? R ? 16 km. We investigate the integral parameters of rapidly rotating stars and obtain evolutionary sequences that correspond to constant rest-mass stars spinning down by electromagnetic and gravitational radiation. Physically new transitional sequences are revealed that are distinguished by a phase transition from nucleonic to color-superconducting matter for some configurations that are located between the static and Keplerian limits. The snapshots of internal structure of the star, displaying the growth or shrinkage of superconducting volume as the star's spin changes, are displayed for constant rest mass stars. We further obtain evolutionary sequences of rotating supramassive compact stars and construct pre-collapse models that can be used as initial data to simulate a collapse of color-superconducting hybrid stars to a black hole.

Ayvazyan, N. S.; Colucci, G.; Rischke, D. H.; Sedrakian, A.

2013-11-01

308

Massive Stars: Stellar Populations  

Microsoft Academic Search

Massive stars dominate the chemical and dynamical evolution of the ISM, and ultimately of their parent galaxy and the universe, because of their fast evolution and intense supersonic winds. Four decades ago, the first rocket UV spectra of massive stars revealed the importance of mass loss and began to change our understanding of their evolution. Recently, advances in stellar modeling,

Luciana Bianchi

2007-01-01

309

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

310

Populations of Carbon Stars  

NASA Astrophysics Data System (ADS)

Carbon stars in the Galaxy do not constitute a single family, but may be divided over several types with distinctive spectroscopic and photometric properties. A subtype of the N stars, characterised by high velocities and weak CN bands, may have been captured by the Milky Way from a cannibalised dwarf galaxy.

Lloyd Evans, T.

2011-09-01

311

Colors of Stars  

NSDL National Science Digital Library

The Colors of Stars Lesson studies how we study temperature of objects through the radiation they emit. This lesson has the student compare three stars in Orion (one red, one whitish-blue, one deep blue) and try to determine which is hottest and which is coolest.

Joiner, David; The Shodor Education Foundation, Inc.

312

Boson Stars under Deconstruction  

E-print Network

We study solutions for boson stars in multiscalar theory. We start with simple models with N scalar theories. Our purpose is to study the models in which the mass matrix of scalars and the scalar couplings are given by an extended method of dimensional deconstruction. The properties of the boson stars are investigated by the Newtonian approximation with the large coupling limit.

Nahomi Kan; Kiyoshi Shiraishi

2010-02-03

313

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

314

The Birth of Massive Stars and Star Clusters  

E-print Network

In the present-day universe, it appears that most, and perhaps all, massive stars are born in star clusters. It also appears that all star clusters contain stars drawn from an approximately universal initial mass function, so that almost all rich young star clusters contain massive stars. In this review I discuss the physical processes associated with both massive star formation and with star cluster formation. First I summarize the observed properties of star-forming gas clumps, then address the following questions. How do these clumps emerge from giant molecular clouds? In these clustered environments, how do individual stars form and gain mass? Can a forming star cluster be treated as an equilibrium system or is this process too rapid for equilibrium to be established? How does feedback affect the formation process?

Jonathan C. Tan

2005-04-11

315

CYP17 polymorphism (rs743572) is associated with increased risk of gallbladder cancer in tobacco users.  

PubMed

Gallbladder cancer (GBC) involves interplay of sex steroids, including estrogen and progesterone. Since CYP17 is a key enzyme involved in estrogen and testosterone hormone biosynthesis as well as in xenobiotic metabolism, it may be a potential candidate gene in the carcinogenesis of the gallbladder. Hence, the present study aimed to investigate the association of CYP17 (rs2486758, and rs743572) polymorphisms with GBC susceptibility. The present study included a total of 414 histologically confirmed GBC and 230 healthy controls. The CYP17 (rs2486758 and rs743572) polymorphisms were genotyped by TaqMan-Allele discrimination assays. Statistical analysis was performed by using SPSS ver. 16. Overall, both the CYP17 SNPs did not indicate any association with GBC risk at genotype, haplotype, or at the genotypic interaction levels. However, in the case-only analysis, CYP rs743572 showed association with increased risk of GBC in tobacco users at hetero genotype and dominant models, as compared to non-user GBC patients. The TCrs2486758-AGrs743572 genotypic combination was also associated with increased GBC susceptibility in tobacco users. CYP17 rs743572 is associated with increased risk of GBC in tobacco users in the North Indian population. However, the study requires confirmation in other populations. PMID:24687554

Rai, Rajani; Sharma, Kiran L; Misra, Sanjeev; Kumar, Ashok; Mittal, Balraj

2014-07-01

316

New Bradyrhizobium japonicum Strains That Possess High Copy Numbers of the Repeated Sequence RS?  

PubMed Central

In a survey of DNA fingerprints of indigenous Bradyrhizobium japonicum with the species-specific repeated sequences RS? and RS?, 21 isolates from three field sites showed numerous RS-specific hybridization bands. The isolates were designated highly reiterated sequence-possessing (HRS) isolates, and their DNA hybridization profiles were easily distinguished from the normal patterns. Some HRS isolates from two field sites possessed extremely high numbers of RS? copies, ranging from 86 to 175 (average, 128), and showed shifts and duplications of nif- and hup-specific hybridization bands. The HRS isolates exhibited slower growth than normal isolates, although no difference in symbiotic properties was detected between the HRS and normal isolates. Nucleotide sequence analysis of 16S rRNA genes showed that HRS isolates were strains of B. japonicum. There was no difference in the spectra of serological and hydrogenase groupings of normal and HRS isolates. Some HRS isolates possessed a tandem repeat RS? dimer that is similar to the structure of (IS30)2, which was shown to cause a burst of transpositional rearrangements in Escherichia coli. The results suggest that HRS isolates are derived from normal isolates in individual fields by genome rearrangements that may be mediated by insertion sequences such as RS?. PMID:9572961

Minamisawa, Kiwamu; Isawa, Tsuyoshi; Nakatsuka, Yoko; Ichikawa, Norikazu

1998-01-01

317

PON1 Q192R polymorphism (rs662) is associated with childhood embryonal tumors.  

PubMed

Genetic susceptibility and environment exposures are associated risk factors in carcinogenesis. Gene polymorphisms that decrease the activity of detoxifying carcinogen substances may modify the effect of exposures. We investigated whether the polymorphisms PON1 rs662 (Q192R), and PON1 rs854560 (L55M) would be associated with embryonal tumors in Brazilian children. Blood samples from 163 children with embryonal tumors and 342 as control group were genotyped by TaqMAN real-time PCR assays. Logistic regression was used to evaluate the association between the polymorphisms of cases and controls groups, adjusted by skin color and age strata. When all tumors were taken together, the presence of the PON1 rs662 (Q192R) variant genotype (RR) was associated with an increased risk of developing embryonal tumors (OR = 2.80, 95 % CI 1.12-7.02). The presence of at least one variant PON1 rs662 R allele increased the risk of developing Wilms´ Tumor although without statistical power. However, it was observed a significant association of PON1 rs662 (Q192R) variant genotype (RR) with retinoblastoma (OR = 4.08, 95 % CI 1.13-14.97), whereas the PON1 rs854560 (L55M) polymorphism was not associated with any tumor. These results indicate that PON1 polymorphisms may have an influence on the risk of developing embryonal tumors. PMID:24972570

Vasconcelos, Gisele M; Gonçalves, Bruno Aguiar Alves; Montalvão-de-Azevedo, Rafaela; Thuler, Luiz Claúdio Santos; Braga, Flavio Henrique Paraguassu; Pombo-de-Oliveira, Maria S; de Camargo, Beatriz

2014-09-01

318

Astrophysics. Volume 1 - Stars  

NASA Astrophysics Data System (ADS)

The text is intended for a senior-level or first-year graduate-level course in astrophysics. Volume 1 covers a wide range of subjects in stellar astrophysics. An overview of stellar structure and evolution is provided, taking into account stars, energy transport and generation in stars, stellar time-scales, static configurations (hydrostatic equilibrium), the virial theorem, relativistic effects, star formation, and stellar evolution. Other subjects discussed are related to properties of matter, aspects of observational astronomy, static stellar structure, radiation and energy transport, atomic properties of matter, nuclear energy soruces, the main sequence, evolution away from the main sequence, deviations from quasi-static evolution, the final stages of stellar evolution, weak interactions in stellar evolution, degenerate stars, supernovae, compact stellar and relativistic objects, and close binary systems. Attention is given to neutron stars, gravitational collapse and black holes, white dwarfs, neutrino energy-loss rates, and solar neutrinos.

Bowers, R. L.; Deeming, T.

319

The First Stars  

E-print Network

The formation of the first generations of stars at redshifts z > 15-20 signaled the transition from the simple initial state of the universe to one of increasing complexity. We here review recent progress in understanding the assembly process of the first galaxies, starting with cosmological initial conditions and modelling the detailed physics of star formation. In particular, we study the role of HD cooling in ionized primordial gas, the impact of UV radiation produced by the first stars, and the propagation of the supernova blast waves triggered at the end of their brief lives. We conclude by discussing how the chemical abundance patterns observed in extremely low-metallicity stars allow us to probe the properties of the first stars.

Jarrett L. Johnson; Thomas H. Greif; Volker Bromm

2008-02-01

320

Electrically charged compact stars  

E-print Network

We review here the classical argument used to justify the electrical neutrality of stars and show that if the pressure and density of the matter and gravitational field inside the star are large, then a charge and a strong electric field can be present. For a neutron star with high pressure (~ 10^{33} to 10^{35} dynes /cm^2) and strong gravitational field (~ 10^{14} cm/s^2), these conditions are satisfied. The hydrostatic equation which arises from general relativity, is modified considerably to meet the requirements of the inclusion of the charge. In order to see any appreciable effect on the phenomenology of the neutron stars, the charge and the electrical fields have to be huge (~ 10^{21} Volts/cm). These stars are not however stable from the viewpoint that each charged particle is unbound to the uncharged particles, and thus the system collapses one step further to a charged black hole

Subharthi Ray; Manuel Malheiro; Jose' P. S. Lemos; Vilson T. Zanchin

2006-04-17

321

IS1631 Occurrence in Bradyrhizobium japonicum Highly Reiterated Sequence-Possessing Strains with High Copy Numbers of Repeated Sequences RS? and RS?  

PubMed Central

From Bradyrhizobium japonicum highly reiterated sequence-possessing (HRS) strains indigenous to Niigata and Tokachi in Japan with high copy numbers of the repeated sequences RS? and RS? (K. Minamisawa, T. Isawa, Y. Nakatsuka, and N. Ichikawa, Appl. Environ. Microbiol. 64:1845–1851, 1998), several insertion sequence (IS)-like elements were isolated by using the formation of DNA duplexes by denaturation and renaturation of total DNA, followed by treatment with S1 nuclease. Most of these sequences showed structural features of bacterial IS elements, terminal inverted repeats, and homology with known IS elements and transposase genes. HRS and non-HRS strains of B. japonicum differed markedly in the profiles obtained after hybridization with all the elements tested. In particular, HRS strains of B. japonicum contained many copies of IS1631, whereas non-HRS strains completely lacked this element. This association remained true even when many field isolates of B. japonicum were examined. Consequently, IS1631 occurrence was well correlated with B. japonicum HRS strains possessing high copy numbers of the repeated sequence RS? or RS?. DNA sequence analysis indicated that IS1631 is 2,712 bp long. In addition, IS1631 belongs to the IS21 family, as evidenced by its two open reading frames, which encode putative proteins homologous to IstA and IstB of IS21, and its terminal inverted repeat sequences with multiple short repeats. PMID:10427040

Isawa, Tsuyoshi; Sameshima, Reiko; Mitsui, Hisayuki; Minamisawa, Kiwamu

1999-01-01

322

Extreme Horizontal Branch Stars  

E-print Network

A review is presented on the properties, origin and evolutionary links of hot subluminous stars which are generally believed to be extreme Horizontal Branch stars or closely related objects. Amongst the field stars a large fraction of sdBs are found to reside in close binaries. The companions are predominantly white dwarfs, or low mass main sequence stars. Systems with sufficiently massive WD companions may qualify as SN Ia progenitors. Recently evidence has been found that the masses of some unseen companions might exceed the Chandrasekhar mass, hence they must be neutron stars or black holes. Even a planet has recently been detected orbiting the pulsating sdB star V391 Peg. Quite to the opposite, in globular clusters, only very few sdB binaries are found indicating that the dominant sdB formation processes is different in a dense environment. Binary population synthesis models identify three formation channels, (i) stable Roche lobe overflow, (ii) one or two common envelope ejection phases and (iii) the merger of two helium white dwarfs. The latter channel may explain the properties of the He-enriched sdO stars because their binary fraction is lower than that of the sdBs by a factor of ten or more. Pulsating subluminous B (sdB) stars play an important role for asteroseismology as this technique has already led to mass determinations for a handful of stars. A unique hyper-velocity sdO star moving so fast that it is unbound to the Galaxy has probably been ejected by the super-massive black hole in the Galactic centre. (abridged)

Ulrich Heber

2008-04-03

323

Photospheric temperature measurements in young main sequence stars  

E-print Network

As part of our program to study stellar photospheric and chromospheric activity, we have examined several young solar type stars with activity levels intermediate between the Sun and the very active RS CVn binaries. We have analysed contemporaneous spectroscopic data obtained at Catania Observatory (Serra La Nave station, Mt. Etna) and photometric data acquired in the Stromgren bands with an automatic photometric telescope (APT) at Fairborn Observatory (Arizona, USA). Surface inhomogeneities have been detected from the rotational modulation of stellar brightness as well as from the modulation of several photospheric line-depth ratios (LDRs). The presence of chromospheric plage-like regions has been inferred from the rotational modulation of the Halpha line equivalent width (EW_Halpha) evaluated with the spectral synthesis method. The most relevant results are the strong correlation between the brightness and temperature curves derived respectively from photometry and the LDRs as well as the striking anti-correlation between brightness and Halpha emission. This suggests a close spatial association of spots and plages, as frequently observed for the largest sunspot groups (e.g., Catalano et al. (1998)) and for some very active RS CVn systems (Catalano et al. 2002). Moreover, a simple spot/plage model applied to the observed flux curves allows a rough reconstruction of photospheric and chromospheric features of young main sequence stars.

K. Biazzo; A. Frasca; G. W. Henry; S. Catalano; E. Marilli

2006-10-18

324

Catch a Star!  

NASA Astrophysics Data System (ADS)

ESO and the European Association for Astronomy Education are launching today the 2007 edition of 'Catch a Star!', their international astronomy competition for school students. Now in its fifth year, the competition offers students the chance to win a once-in-a-lifetime trip to ESO's flagship observatory in Chile, as well as many other prizes. Students are invited to 'become astronomers' and embark on a journey to explore the Universe. ESO PR Photo 42/06 The competition includes separate categories - 'Catch a Star Researchers' and 'Catch a Star Adventurers' - to ensure that every student, whatever their level, has the chance to enter and win exciting prizes. For the artistically minded, 'Catch a Star!' also includes an artwork competition, 'Catch a Star Artists'. "'Catch a Star!' offers a unique opportunity for students to learn more about astronomy and about the methods scientists use to discover new things about the Universe", said Douglas Pierce-Price, Education Officer at ESO. In teams, students choose an astronomical topic to study and produce an in-depth report. An important part of the project for 'Catch a Star Researchers' is to think about how ESO's telescopes or a telescope of the future can contribute to their investigations of the subject. As well as the top prize - a trip to one of ESO's observatory sites in Chile - visits to observatories in Germany, Austria and Spain, and many other prizes are also available to be won. 'Catch a Star Researchers' winners will be chosen by an international jury, and 'Catch a Star Adventurers' will be awarded further prizes by lottery. Entries for 'Catch a Star Artists' will be displayed on the web and winners chosen with the help of a public online vote. The first editions of 'Catch a Star!' have attracted several hundred entries from more than 25 countries worldwide. Previous winning entries have included "Star clusters and the structure of the Milky Way" (Budapest, Hungary), "Vega" (Acqui Terme, Italy) and "Venus transit" (Lleida, Spain). Some previous winning entries are visible on the Catch a Star! Web site. Detailed entry information can be found on ESO's website, at http://www.eso.org/catchastar/ The deadline for submitting an entry for the 2007 competition is Friday 2 March 2007, 17:00 Central European Time.

2006-11-01

325

A SUPER-EARTH AND TWO NEPTUNES ORBITING THE NEARBY SUN-LIKE STAR 61 VIRGINIS  

SciTech Connect

We present precision radial velocity data that reveal a multiple exoplanet system orbiting the bright nearby G5V star 61 Virginis. Our 4.6 years of combined Keck/HIRES and Anglo-Australian Telescope precision radial velocities indicate the hitherto unknown presence of at least three planets orbiting this well-studied star. These planets are all on low-eccentricity orbits with periods of 4.2, 38.0, and 124.0 days, and projected masses (Msin i) of 5.1, 18.2, and 24.0 M{sub +}, respectively. Test integrations of systems consistent with the radial velocity data suggest that the configuration is dynamically stable. Depending on the effectiveness of tidal dissipation within the inner planet, the inner two planets may have evolved into an eccentricity fixed-point configuration in which the apsidal lines of all three planets corotate. This conjecture can be tested with additional observations. We present a 16-year time series of photometric observations of 61 Virginis, which comprise 1194 individual measurements, and indicate that it has excellent photometric stability. No significant photometric variations at the periods of the proposed planets have been detected. This new system is the first known example of a G-type Sun-like star hosting a Super-Earth mass planet. It joins HD 75732 (55 Cnc), HD 69830, GJ 581, HD 40307, and GJ 876 in a growing group of exoplanet systems that have multiple planets orbiting with periods less than an Earth-year. The ubiquity of such systems portends that space-based transit-search missions such as Kepler and CoRoT will find many multi-transiting systems.

Vogt, Steven S.; Rivera, Eugenio J.; Meschiari, Stefano; Laughlin, Gregory [UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); Wittenmyer, Robert A.; Tinney, C. G.; Bailey, Jeremy [Department of Astrophysics, School of Physics, University of New South Wales, NSW 2052 (Australia); Butler, R. Paul [Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, NW, Washington, DC 20015-1305 (United States); O'Toole, Simon; Jones, Hugh R. A. [Centre for Astrophysical Research, University of Hertfordshire, Hatfield, AL10 9AB (United Kingdom); Henry, Gregory W. [Center of Excellence in Information Systems, Tennessee State University, Nashville, TN 37209 (United States); Carter, Brad D. [Faculty of Sciences, University of Southern Queensland, Toowoomba, Queensland 4350 (Australia); Batygin, Konstantin [Department of Geological and Planetary Sciences, Caltech, Pasadena, CA 91125 (United States)

2010-01-10

326

A Super-Earth and Two Neptunes Orbiting the Nearby Sun-like Star 61 Virginis  

NASA Astrophysics Data System (ADS)

We present precision radial velocity data that reveal a multiple exoplanet system orbiting the bright nearby G5V star 61 Virginis. Our 4.6 years of combined Keck/HIRES and Anglo-Australian Telescope precision radial velocities indicate the hitherto unknown presence of at least three planets orbiting this well-studied star. These planets are all on low-eccentricity orbits with periods of 4.2, 38.0, and 124.0 days, and projected masses (Msin i) of 5.1, 18.2, and 24.0 M ?, respectively. Test integrations of systems consistent with the radial velocity data suggest that the configuration is dynamically stable. Depending on the effectiveness of tidal dissipation within the inner planet, the inner two planets may have evolved into an eccentricity fixed-point configuration in which the apsidal lines of all three planets corotate. This conjecture can be tested with additional observations. We present a 16-year time series of photometric observations of 61 Virginis, which comprise 1194 individual measurements, and indicate that it has excellent photometric stability. No significant photometric variations at the periods of the proposed planets have been detected. This new system is the first known example of a G-type Sun-like star hosting a Super-Earth mass planet. It joins HD 75732 (55 Cnc), HD 69830, GJ 581, HD 40307, and GJ 876 in a growing group of exoplanet systems that have multiple planets orbiting with periods less than an Earth-year. The ubiquity of such systems portends that space-based transit-search missions such as Kepler and CoRoT will find many multi-transiting systems.

Vogt, Steven S.; Wittenmyer, Robert A.; Butler, R. Paul; O'Toole, Simon; Henry, Gregory W.; Rivera, Eugenio J.; Meschiari, Stefano; Laughlin, Gregory; Tinney, C. G.; Jones, Hugh R. A.; Bailey, Jeremy; Carter, Brad D.; Batygin, Konstantin

2010-01-01

327

Association study of SNPs of genes IFNGR1 (rs137854905), GSTT1 (rs71748309), and GSTP1 (rs1695) in gastric cancer development in samples of patient in the northern and northeastern Brazil.  

PubMed

Cancer is a multifactorial disease with a high mortality rate in Brazil and worldwide. Gastric cancer (GC) is considered the fourth type of malignancy more frequent in the population worldwide and the second leading cause of death. This work aimed to evaluate single nucleotide polymorphisms (SNPs) of IFNGR1, GSTT1, and GSTP1 genes samples in gastric cancer. We analyzed 60 samples of gastric cancer, 26 diffuse and 34 intestinal types, totaling 120 alleles for each SNP. The results were obtained by PCR and allele-specific PCR. Statistical analyzes performed using BioEstat 5.0 software, applying the Fisher's exact test and chi-square. Only the SNP gene GSTP1 (rs1695) were significantly associated with gastric cancer in the samples analyzed (?(2)?=?8.73, P?rs1695) can be considered a risk factor associated with gastric carcinogenesis. PMID:24453034

de Araújo, Rubistenia Miranda Soares; de Melo, Cynthia Farias Vieira; Neto, Fidelis Manes; da Silva, Juarez Nóbrega; Soares, Leonardo Ferreira; de Arruda Cardoso Smith, Marilia; Sousa, Edilson Carvalho; Burbano, Rommel Mario Rodríguez; de Medeiros, Arnaldo Correia; Lima, Eleonidas Moura

2014-05-01

328

On stars and Steiner stars. II Adrian Dumitrescu  

E-print Network

On stars and Steiner stars. II Adrian Dumitrescu Csaba D. T´oth Guangwu Xu June 26, 2008 Abstract A Steiner star for a set P of n points in Rd connects an arbitrary center point to all points of P, while a star connects a point p P to the remaining n-1 points of P. All connections are realized by straight

Dumitrescu, Adrian

329

On stars and Steiner stars Adrian Dumitrescu # Csaba D. Toth +  

E-print Network

On stars and Steiner stars Adrian Dumitrescu # Csaba D. Tâ??oth + February 26, 2008 Abstract For a set of n points in the plane, a star connects one of the points (the center) to the other n - 1 points by straight line edges, while a Steiner star connects an arbitrary point in the plane to all n input points

Dumitrescu, Adrian

330

Contribution à l'etude des binaires des types F, G, K, M IX. HD 191588, nouvelle binaire spectroscopique à raies simples de type RS Cvn, systeme triple  

E-print Network

An accident of misidentification has brought to light the interesting system HD 191588, a new RS CVn-type spectroscopic binary. A radial-velocity study of the primary star, the only seen component, carried out at the Observatoire de Haute-Provence with the Coravel instrument and subsequently at the Cambridge Observatories with a similar one, reveals two orbital motions: a short-period orbit (60 days) and a long-period one (about 4.5 years), so this star is a triple system. The following orbital elements are obtained: (1) for the long-period orbit P = 1667+/-17 days, T = 50901 +/-67 MJD, Gamma = +2.09 +/-0.07 km/s, K = 2.51 +/-0.13 km/s, e = 0.18 +/-0.04, omega = 228deg +/- 14 deg, a1 sin i = 56.7 +/- 3.0 Gm, f(m) = 0.0026 +/-0.0004 M_sun, and (2) for the short-period orbit P = 60.0269 +/-0.0016 days, T = 50482.6 +/-3.3 MJD, gamma is var., K = 24.03 +/- 0.09 km/s, e = 0.012 +/-0.004, omega = 233 deg +/-19deg, a1 sin i = 19.83 +/-0.07 Gm, f(m) = 0.0865 +/-0.0009 M_sun. From near-infrared observations we refine the classification of the primary component and we found a spectral type of K2.5 III, and a spectrum obtained in the blue--near-UV spectral region reveals strong H and K emission lines of Ca II. The unseen secondary should be a solar-type star (F or G V); the minimum mass of the third body is that of a dwarf M star. Probably, the primary component rotates in synchronism with the orbital motion in the inner orbit; a model, based upon that hypothesis, is proposed for the system, and finally the connection of the inner binary to the long-period RS CVn group (Hall 1976) is discussed.

Roger R. F. Griffin; Nicole Ginestet; Jean-Michel Carquillat

2007-02-28

331

Measuring stars with Gaia  

NASA Astrophysics Data System (ADS)

Beyond the extraordinary three dimensional map that Gaia will create for a billion of stars, it will reveal the origin and history of the Milky Way as the major goal. This does not weakness the fantastic impact of Gaia on the stellar physic. It will put constraints on the modeling of stars to an extreme that consequently new input physics will be mandatory to understand a Gaia HR diagram. Stars are formed in populations and evolve as collection of objects revealing important clues on how they formed, what kind of mass function is active during the star formation, how frequent is the star formation, all of this is imprinted in the intrinsic properties of stars that large surveys combined together like Gaia, Kepler, PLATO will revealed. The characterization of stars hosting planets is also a goal of such combination of large surveys and in particular of the measure of distances in the Galaxy. The launch of Gaia is for November of 2013 and the output catalogue is expected for 2020. Then will start the beginning of a new Astrophysics touching so many topics that a new age of astrophysics is then foreseen.

Thévenin, F.

2013-12-01

332

Intergalactic Star Formation  

E-print Network

Star formation in interacting systems may take place in various locations, from the dust--enshrouded core of Ultraluminous Infrared Galaxies to more unusual places such as the debris of colliding galaxies expelled into the intergalactic medium. Determining whether star-formation proceeds in the latter environment, far from the parent galaxies, in a similar way as in spiral disks has motivated the multi--wavelength study presented here. We collected VLA/HI, UV/GALEX, optical Halpha and MIR/Spitzer images of a few nearby interacting systems chosen for their prominent "intergalactic" star formation activity. Preliminary results on the spectacular collisional HI ring around NGC 5291 are presented.

Duc, P A; Braine, J; Brinks, E; Lisenfeld, U; Charmandaris, V; Duc, Pierre-Alain; Boquien, Meederic; Braine, Jonathan; Brinks, Elias; Lisenfeld, Ute; Charmandaris, Vassilis

2006-01-01

333

Intergalactic Star Formation  

E-print Network

Star formation in interacting systems may take place in various locations, from the dust--enshrouded core of Ultraluminous Infrared Galaxies to more unusual places such as the debris of colliding galaxies expelled into the intergalactic medium. Determining whether star-formation proceeds in the latter environment, far from the parent galaxies, in a similar way as in spiral disks has motivated the multi--wavelength study presented here. We collected VLA/HI, UV/GALEX, optical Halpha and MIR/Spitzer images of a few nearby interacting systems chosen for their prominent "intergalactic" star formation activity. Preliminary results on the spectacular collisional HI ring around NGC 5291 are presented.

Pierre-Alain Duc; Meederic Boquien; Jonathan Braine; Elias Brinks; Ute Lisenfeld; Vassilis Charmandaris

2006-10-13

334

Finding the Pole Star  

NSDL National Science Digital Library

This lesson plan is part of a high school course on astronomy, Newtonian mechanics and spaceflight and provides a closer look at the pole star and the neighboring constellations, especially the Big Dipper and Cassiopeia. One objective is for the student to know the constellations of the Big Dipper and Cassiopeia, and their use in finding the Pole Star. The student will also realize that other celestial objects - Sun, Moon and planets - share the rotation (and hence rise and set), even though their positions among the stars slowly change.

Stern, David

335

Spectroscopy of ? Doradus stars  

NASA Astrophysics Data System (ADS)

The musician programme at the University of Canterbury has been successfully identifying pulsation modes in many ? Doradus stars using hundreds of ground-based spectroscopic observations. This paper describes some of the successful mode identifications and emerging patterns of the programme. The hybrid ? Doradus/? Scuti star HD 49434 remains an enigma, despite the analysis of more than 1700 multi-site high-resolution spectra. A new result for this star is apparently distinct line-profile variations for the ? Doradus and ? Scuti frequencies.

Brunsden, E.; Pollard, K. R.; Cottrell, P. L.; Wright, D. J.; De Cat, P.; Kilmartin, P. M.

2014-02-01

336

Life Products of Stars  

E-print Network

We attempt to document complete energetic transactions of stars in their life. We calculate photon and neutrino energies that are produced from stars in their each phase of evolution from 1 to 8 M_sun, using the state-of-the-art stellar evolution code, tracing the evolution continuously from pre-main sequence gravitational contraction to white dwarfs. We also catalogue gravitational and thermal energies and helium, and heavier elements that are stored in stars and those ejected into interstellar space in each evolutionary phase.

Aldo M. Serenelli; Masataka Fukugita

2006-06-27

337

Kepler Star Wheels  

NSDL National Science Digital Library

This is a make-it-yourself planisphere designed to show where Kepler is pointing. Learners can use it to locate exoplanets around stars in the night sky. It comes with two wheels: one with coordinate grid for plotting additional exoplanet stars and one without grid that is easier to read; and two holders for varying latitudes (one for 30°-50° and one for 50°-70°). The product is updated approximately annually to incorporate improvements and any newly discovered planets orbiting naked eye stars.

338

StarDate Online  

NSDL National Science Digital Library

This on-line version of StarDate astronomy magazine provides current viewing information, a sky almanac, Moon phase calculator, sunrise and sunset calculator, planet viewing information, and meteor shower updates. News and Features contains information and details on the latest findings and research in the field of astronomy. Resources contains an image gallery, an astroglossary, and solar system, constellation, and star guides. The Radio section contains past radio programs by date, or searchable by subject. Also available are an archive database of past StarDate articles, and a teacher's section with ideas for teaching astronomy concepts in the classroom.

339

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

340

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

341

Can Boltzmann Soliton Star Exist?  

NASA Astrophysics Data System (ADS)

The fermion soliton stars suggested by Lee and Pang are extended to finite temperature. The degeneracy temperature TD above which the fermion soliton star will become a Boltzmann soliton star is given. We prove that the Boltzmann soliton star cannot exist, because it is unstable.

Su, Rukeng; Chen, Xuelei; Pan, Rongshi

1992-12-01

342

Genetic variants in PARP1 (rs3219090) and IRF4 (rs12203592) genes associated with melanoma susceptibility in a Spanish population  

PubMed Central

Background Few high penetrance genes are known in Malignant Melanoma (MM), however, the involvement of low-penetrance genes such as MC1R, OCA2, ASIP, SLC45A2 and TYR has been observed. Lately, genome-wide association studies (GWAS) have been the ideal strategy to identify new common, low-penetrance susceptibility loci. In this case–control study, we try to validate in our population nine melanoma associated markers selected from published GWAS in melanoma predisposition. Methods We genotyped the 9 markers corresponding to 8 genes (PARP1, MX2, ATM, CCND1, NADSYN1, CASP8, IRF4 and CYP2R1) in 566 cases and 347 controls from a Spanish population using KASPar probes. Genotypes were analyzed by logistic regression and adjusted by phenotypic characteristics. Results We confirm the protective role in MM of the rs3219090 located on the PARP1 gene (p-value 0.027). Additionally, this SNP was also associated with eye color (p-value 0.002). A second polymorphism, rs12203592, located on the IRF4 gene was associated with protection to develop MM for the dominant model (p-value 0.037). We have also observed an association of this SNP with both lentigines (p-value 0.014) and light eye color (p-value 3.76?×?10-4). Furthermore, we detected a novel association with rs1485993, located on the CCND1 gene, and dark eye color (p-value 4.96?×?10-4). Finally, rs1801516, located on the ATM gene, showed a trend towards a protective role in MM similar to the one firstly described in a GWAS study. Conclusions To our knowledge, this is the first time that these SNPs have been associated with MM in a Spanish population. We confirmed the proposed role of rs3219090, located on the PARP1 gene, and rs12203592, located on the IRF4 gene, as protective to MM along the same lines as have previous genome-wide associated works. Finally, we have seen associations between IRF4, PARP1, and CCND1 and phenotypic characteristics, confirming previous results for the IRF4 gene and presenting novel data for the last two, suggesting that pigmentation characteristics correlated with eye color are potential mediators between PARP1 and MM protection. PMID:23537197

2013-01-01

343

Association of methionine synthase rs1801394 and methionine synthase reductase rs1805087 polymorphisms with meningioma in adults: A meta-analysis  

PubMed Central

Several epidemiological studies suggested that methionine synthase (MTRR) rs1801394 and methionine synthase reductase (MTR) rs1805087 polymorphisms may be involved in the risk of meningioma in adults; however, the results from different case-control studies have been inconsistent. Therefore, we performed a meta-analysis to investigate the association of MTRR and MTR polymorphisms with meningioma. PubMed, Web of Knowledge, China National Knowledge Infrastructure and Wanfang databases were searched up to October 30, 2013 and 3 publications, involving 7 case-control studies, were finally included. Following data extraction, a meta-analysis was conducted using Stata 12.0 software. The pooled results based on the fixed effects model demonstrated that the MTRR rs1801394 polymorphism was associated with an increased risk of meningioma [odds ratio (OR)=1.18, 95% confidence interval (CI): 1.05–1.32 for G vs. A; OR=1.41, 95% CI: 1.12–1.77 for GG vs. AA; OR=1.08, 95% CI: 0.94–1.33 for AG vs. AA; OR=1.19, 95% CI: 1.01–1.40 for (AG+GG) vs. AA; and OR=1.32, 95% CI: 1.07–1.63 for GG vs. (AG+AA)]; however, an association between the MTR rs1805087 polymorphism and the risk of meningioma was not identified [OR=0.99, 95% CI: 0.88–1.12 for G vs. A; OR=1.09, 95% CI: 0.80–1.48 for GG vs. AA; OR=0.95, 95% CI: 0.82–1.11 for AG vs. AA; OR=0.97, 95% CI: 0.84–1.13 for (AG+GG) vs. AA; and OR=1.09, 95% CI: 0.80–1.48 for GG vs. (AG+AA)]. Therefore, the currently available evidence suggests that the MTRR rs1801394 polymorphism may increase the risk of meningioma, whereas the MTRR rs1801394 polymorphism is not associated with meningioma. PMID:24748989

ZENG, XIAN-TAO; LU, JUN-TI; TANG, XIANG-JUN; WENG, HONG; LUO, JIE

2014-01-01

344

The CYP7A1 gene rs3808607 variant is associated with susceptibility of tuberculosis in Moroccan population  

PubMed Central

Introduction Despite the medical progress in treatment. Tuberculosis (TB) continues to be a serious global health problem. A genome-wide linkage study identified a major susceptibility locus on chromosomal region 8q12-q13 in Moroccan TB patients. The CYP7A1 gene is located in this region and codes for cholesterol 7a-hydroxylase, an enzyme involved in cholesterol catabolism. Methods We selected three SNPs (rs3808607, rs8192875 and rs8192879) and studied their genotype and allele frequencies distribution in patients with pulmonary (PTB) or pleural TB (pTB), and compared them to Healthy Controls (HC). Genotyping of rs8192875 and rs8192879 SNPs was carried out using the Taq Man SNP genotyping Assay while rs3808607 was investigated by PCR-RFLP. Results We reported here for the first time a statistically significant increase in the AA homozygote genotype frequency of rs3808607 in PTB patients compared to HC (p = 0.02, OR = 1.93, 95% CI: 1.93 (1.07;3.49). The increased risk of developing TB was maintained when we combined the groups of patients (PTB-pTB) (p = 0.01, OR= 1.91, 95% CI = (1.07 - 3.42). In contrast, no genetic association was observed between the rs8192875 or rs8192879 polymorphisms and TB. Conclusion Our investigations suggest that rs3808607 may play a role in susceptibility to TB in a Moroccan population. PMID:25360185

Qrafli, Mounia; Amar, Youssef; Bourkadi, Jamaleddine; Ben Amor, Jouda; Iraki, Ghali; Bakri, Youssef; Amzazi, Saaid; Lahlou, Ouafae; Seghrouchni, Fouad; El Aouad, Rajae; Sadki, Khalid

2014-01-01

345

Hypernuclear Physics for Neutron Stars  

E-print Network

The role of hypernuclear physics for the physics of neutron stars is delineated. Hypernuclear potentials in dense matter control the hyperon composition of dense neutron star matter. The three-body interactions of nucleons and hyperons determine the stiffness of the neutron star equation of state and thereby the maximum neutron star mass. Two-body hyperon-nucleon and hyperon-hyperon interactions give rise to hyperon pairing which exponentially suppresses cooling of neutron stars via the direct hyperon URCA processes. Non-mesonic weak reactions with hyperons in dense neutron star matter govern the gravitational wave emissions due to the r-mode instability of rotating neutron stars.

Jurgen Schaffner-Bielich

2008-01-24

346

Analyzing Starspots with TiO bands: Comparing Fits Using Synthetic Spectra to Proxy Stars  

NASA Astrophysics Data System (ADS)

In several studies, we have measured starspot filling factors and temperatures on magnetically active stars using TiO bands. In the past we have used proxy star spectra to model the spots and the inactive photosphere of the active stars. Now, we extend this work by using model atmospheres and synthetic spectra, based on the Atlas9 models, to fit the spectra of active stars. We have studied our past spectra of several giant/subgiant RS CVn and dwarf BY Dra active stars, including an extensive data set on II Pegasi. We find systematic differences between the starspot parameters obtained using proxy stars and synthetic spectra. When only the 7055 A TiO band is used and a spot temperature is assumed, we compute ~0.1 lower spot filling factor when synthetic spectra are used compared to proxy stars. When the 7055 A and 8860 A TiO bands are used simultaneously, we systematically find a slightly higher spot filling factor and a spot temperature ~200 K lower using synthetic spectra. We are currently working to explain these differences.

O'Neal, Douglas B.; Skivington, J. R.

2014-01-01

347

RS-34 Phoenix In-Space Propulsion System Applied to Active Debris Removal Mission  

NASA Technical Reports Server (NTRS)

In-space propulsion is a high percentage of the cost when considering Active Debris Removal mission. For this reason it is desired to research if existing designs with slight modification would meet mission requirements to aid in reducing cost of the overall mission. Such a system capable of rendezvous, close proximity operations, and de-orbit of Envisat class resident space objects has been identified in the existing RS-34 Phoenix. RS-34 propulsion system is a remaining asset from the de-commissioned United States Air Force Peacekeeper program; specifically the pressure-fed storable bi-propellant Stage IV Post Boost Propulsion System. The National Aeronautics and Space Administration (NASA) Marshall Space Flight Center (MSFC) gained experience with the RS-34 propulsion system on the successful Ares I-X flight test program flown in the Ares I-X Roll control system (RoCS). The heritage hardware proved extremely robust and reliable and sparked interest for further utilization on other potential in-space applications. Subsequently, MSFC has obtained permission from the USAF to obtain all the remaining RS-34 stages for re-use opportunities. The MSFC Advanced Concepts Office (ACO) was commissioned to lead a study for evaluation of the Rocketdyne produced RS-34 propulsion system as it applies to an active debris removal design reference mission for resident space object targets including Envisat. Originally designed, the RS-34 Phoenix provided in-space six-degrees-of freedom operational maneuvering to deploy payloads at multiple orbital locations. The RS-34 Concept Study lead by sought to further understand application for a similar orbital debris design reference mission to provide propulsive capability for rendezvous, close proximity operations to support the capture phase of the mission, and deorbit of single or multiple large class resident space objects. Multiple configurations varying the degree of modification were identified to trade for dry mass optimization and propellant load. The results of the RS-34 Phoenix Concept Study show that the system is technically sufficient to successfully support all of the missions to rendezvous, capture, and de-orbit targets including Envisat and Hubble Space Telescope. The results and benefits of the RS-34 Orbital Debris Application Concept Study are presented in this paper.

Esther, Elizabeth A.; Burnside, Christopher G.

2014-01-01

348

Cooling of neutron stars  

NASA Technical Reports Server (NTRS)

It is at present impossible to predict the interior constitution of neutron stars based on theory and results from laboratory studies. It has been proposed that it is possible to obtain information on neutron star interiors by studying thermal radiation from their surfaces, because neutrino emission rates, and hence the temperature of the central part of a neutron star, depend on the properties of dense matter. The theory predicts that neutron stars cool relatively slowly if their cores are made up of nucleons, and cool faster if the matter is in an exotic state, such as a pion condensate, a kaon condensate, or quark matter. This view has recently been questioned by the discovery of a number of other processes that could lead to copious neutrino emission and rapid cooling.

Pethick, C. J.

1992-01-01

349

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

350

Violent Star Formation  

NASA Astrophysics Data System (ADS)

This volume deals with the most recent theories of violent star formation. It covers the formation and evolution of new stellar clusters, and explores all the possible consequences in a wide variety of objects where massive stellar bursts have occurred. It thus presents an alternative model to that which suggests supermassive black holes are the power houses of active glactic nuclei. In addition, it analyzes the impact of Wolf-Rayet stars, stellar winds and supernovae on their host galaxy, and provides evidence of massive superassociations and of supersonic velocity dispersions that result from photo-ionization by violent star formation. This book gives a valuable overview and a timely update on all aspects of violent star formation for graduate students and researchers in the field.

Tenorio-Tagle, G.

1995-01-01

351

Guide star probabilities  

NASA Technical Reports Server (NTRS)

Probabilities are calculated for acquiring suitable guide stars (GS) with the fine guidance system (FGS) of the space telescope. A number of the considerations and techniques described are also relevant for other space astronomy missions. The constraints of the FGS are reviewed. The available data on bright star densities are summarized and a previous error in the literature is corrected. Separate analytic and Monte Carlo calculations of the probabilities are described. A simulation of space telescope pointing is carried out using the Weistrop north galactic pole catalog of bright stars. Sufficient information is presented so that the probabilities of acquisition can be estimated as a function of position in the sky. The probability of acquiring suitable guide stars is greatly increased if the FGS can allow an appreciable difference between the (bright) primary GS limiting magnitude and the (fainter) secondary GS limiting magnitude.

Soneira, R. M.; Bahcall, J. N.

1981-01-01

352

Neutron stars - thermal emitters  

E-print Network

Confronting theoretical models with observations of thermal radiation emitted by neutron stars is one of the most important ways to understand the properties of both, superdense matter in the interiors of the neutron stars and dense magnetized plasmas in their outer layers. Here we review the theory of thermal emission from the surface layers of strongly magnetized neutron stars, and the main properties of the observational data. In particular, we focus on the nearby sources for which a clear thermal component has been detected, without being contaminated by other emission processes (magnetosphere, accretion, nebulae). We also discuss the applications of the modern theoretical models of the formation of spectra of strongly magnetized neutron stars to the observed thermally emitting objects.

Potekhin, A Y; Pons, J A

2014-01-01

353

Miniature star tracker  

NASA Astrophysics Data System (ADS)

Hughes Danbury Optical Systems, Inc. (HDOS) is developing a new generation of star trackers that combine low-weight and power consumption with high performance, high reliability, and survivability. Our Miniature Star Tracker (MST), Model HD-1003, represents our next step in the evolution of our advanced star tracker (ASTRA) family of CCD-based star trackers and stresses compact packaging to minimize the impact on the spacecraft design. Small size lowers tracker procurement, integration and launch costs, and provides the user with a high degree of flexibility in selecting the optimum attitude sensor suite, especially for small-sats. Weighing less than 6 lbs, our MST incorporates the latest detector, processor, and application- specific integrated circuit (ASIC) electronics technology to provide exceptional accuracy and survivability in the natural, proton-rich space environment.

Cassidy, Lawrence W.

1993-09-01

354

Soft Physics from STAR  

E-print Network

New results on soft hadron distributions and correlations measured with the STAR experiment are presented. Knowledge about the bulk properties of relativistic heavy-ion collisions offered by these results is discussed.

Fuqiang Wang

2005-10-24

355

Planets Around Evolved Stars  

NASA Astrophysics Data System (ADS)

With searches of planets around evolved pulsating B sub-dwarfs, red giant stars, and white dwarfs underway, it is paramount to advance theoretical research in how stellar evolution affects the architecture of planetary systems. This will not only maximize the discovery potential of said searches, but also aid in the interpretation and understanding of planet formation in a broader context. To acquire a full picture of the planet´s survival process we compute the evolution of the planet´s orbit coupled with the evolution of the star from the main sequence all the way to the white dwarf domain. We explore the range of planetary masses that might survive a common envelope stage during the giant phases of the star and, finally, we investigate how the presence of a planet might influence the evolution of the star itself.

Villaver, Eva; Livio, M.

2011-09-01

356

Alternative CHRNB4 3?-UTRs Mediate the Allelic Effects of SNP rs1948 on Gene Expression  

PubMed Central

Common genetic factors strongly contribute to both nicotine, the main addictive component of tobacco, and alcohol use. Several lines of evidence suggest nicotinic acetylcholine receptors as common sites of action for nicotine and alcohol. Specifically, rs1948, a single-nucleotide polymorphism (SNP) located in the CHRNB4 3?-untranslated region (UTR), has been associated to early age of initiation for both alcohol and tobacco use. To determine the allelic effects of rs1948 on gene expression, two rs1948-containing sequences of different lengths corresponding to the CHRNB4 3?-UTR were cloned into pGL3-promoter luciferase reporter vectors. Data obtained showed that the allelic effects of SNP rs1948 on luciferase expression are mediated by the length and species of transcripts generated. In addition, it was found that miR-3157 increased the overall luciferase expression while miR-138, a microRNA known to play a role in neuroadaptation to drug abuse, decreased luciferase expression when compared to basal conditions. These findings demonstrate the importance of SNP rs1948 on the regulation of CHRNB4 expression and provide the first evidence of CHRNB4 down-regulation by miR-138. PMID:23691088

Gallego, Xavier; Cox, Ryan J.; Laughlin, James R.; Stitzel, Jerry A.; Ehringer, Marissa A

2013-01-01

357

NQO1 gene rs1800566 variant is not associated with risk for multiple sclerosis  

PubMed Central

Background A possible role of oxidative stress in the pathogenesis of multiple sclerosis (MS) and in experimental autoimmune encephalomyelitis has been suggested. The detoxification enzyme NAD(P)H dehydrogenase, quinone 1 (NQO1) has been found up-regulated in MS lesions. A previous report described an association between the SNP rs1800566 in the NQO1 gene and the risk for MS in the Greek population. The aim of this study was to replicate a possible influence of the. SNP rs1800566 in the NQO1 gene in the risk for MS in the Spanish Caucasian population. Methods We analyzed allelic and genotypic frequency of NQO1 rs1800566 in 290 patients with MS and 310 healthy controls, using TaqMan Assays. Results NQO1 rs1800566 allelic and genotypic frequencies did not differ significantly between MS patients and controls, and were unrelated with age of onset of MS, gender, and clinical type of MS. Conclusions Our results indicate that NQO1 rs1800566 does not have an effect on MS disease risk. PMID:24755231

2014-01-01

358

EGF rs11568835 G/A polymorphism is associated with increased risk of rheumatoid arthritis.  

PubMed

Abstract Rheumatoid arthritis (RA) is an autoimmune rheumatological disease thought to have substantial genetic contributions. Epidermal growth factor (EGF) can activate DNA synthesis and cellular proliferation. Early RA synovial fluid was characterized by significantly elevated levels stromal cell and macrophage-related cytokines including EGF. We therefore hypothesized that EGF polymorphisms may contribute to RA susceptibility in the Chinese population. We studied EGF rs11568835 G/A and EGF rs3756261 T/C polymorphisms in 520 patients with RA and 520 controls in a Chinese population. When the EGF rs11568835 GG homozygote genotype was used as the reference group, the AA genotype was associated with an increased risk for RA (AA versus GG, odds ratio [OR]?=?3.64, 95% confidence interval [CI]?=?1.19-11.17, p?=?0.024), the GA or GA/AA genotype was not associated with the risk for RA (GA versus GG, OR?=?0.99, 95% CI?=?0.75-1.31, p?=?0.931; GA?+?AA versus GG, OR?=?1.06, 95% CI?=?0.81-1.40, p?=?0.659). EGF rs3756261 T/C was not associated with susceptibility to RA. These results provide the first positive evidence for an association between EGF rs11568835 G/A polymorphism and RA. PMID:25089940

Wang, Liqun; Bo, Lin; Yan, Ting; Zhang, Hui; Zhou, Guoxin; Liu, Ruiping

2014-11-01

359

Reinvestigation of microwave spectrum of dimethyl ether and rs structures of analogous molecules  

NASA Astrophysics Data System (ADS)

Microwave spectra of dimethyl ether and its sixteen isotopic species have been measured. For species with singlet spectra, a least-squares analysis of observed transition frequencies gave rotational and five quartic centrifugal distortion constants. For species with multiplet spectra due to the methyl internal rotation, a least-squares analysis of observed multiplet frequencies gave not only unperturbed rotational and five quartic centrifugal distortion constants but also the quantities related to the methyl internal rotation. The rs structures from (CH 3) 2O, CH 3OCD 3, and (CD 3) 2O species as the parent species, respectively, were compared with one another. The proposed rs structure has been established from all the species measured and was compared with the rs-like structure obtained by a diagnostic least-squares method and with the reported structure. The rs structure of the present molecule was compared with the reported structures of dimethyl sulfide and dimethyl silane in relation to the tilt phenomenon. The rs structure of dimethyl sulfide was revised based on the present comparison.

Niide, Yuzuru; Hayashi, Michiro

2003-07-01

360

Catch a Star 2008!  

NASA Astrophysics Data System (ADS)

ESO and the European Association for Astronomy Education have just launched the 2008 edition of 'Catch a Star', their international astronomy competition for school students. Now in its sixth year, the competition offers students the chance to win a once-in-a-lifetime trip to ESO's flagship observatory in Chile, as well as many other prizes. CAS logo The competition includes separate categories - 'Catch a Star Researchers' and 'Catch a Star Adventurers' - to ensure that every student, whatever their level, has the chance to enter and win exciting prizes. In teams, students investigate an astronomical topic of their choice and write a report about it. An important part of the project for 'Catch a Star Researchers' is to think about how ESO's telescopes such as the Very Large Telescope (VLT) or future telescopes such as the Atacama Large Millimeter/submillimeter Array (ALMA) and the European Extremely Large Telescope (E-ELT) could contribute to investigations of the topic. Students may also include practical activities such as observations or experiments. For the artistically minded, 'Catch a Star' also offers an artwork competition, 'Catch a Star Artists'. Last year, hundreds of students from across Europe and beyond took part in 'Catch a Star', submitting astronomical projects and artwork. "'Catch a Star' gets students thinking about the wonders of the Universe and the science of astronomy, with a chance of winning great prizes. It's easy to take part, whether by writing about astronomy or creating astronomically inspired artwork," said Douglas Pierce-Price, Education Officer at ESO. As well as the top prize - a trip to ESO's Very Large Telescope in Chile - visits to observatories in Austria and Spain, and many other prizes, can also be won. 'Catch a Star Researchers' winners will be chosen by an international jury, and 'Catch a Star Adventurers' will be awarded further prizes by lottery. Entries for 'Catch a Star Artists' will be displayed on the web and winners chosen with the help of a public online vote. Detailed entry information and rules can be found at http://www.eso.org/catchastar/cas2008/. The deadline for submitting an entry for the 2008 competition is Friday 29 February 2008, 17:00 Central European Time.

2007-10-01

361

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

362

Matter accreting neutron stars  

NASA Technical Reports Server (NTRS)

Some of the fundamental neutron star parameters, such as the mass and the magnetic field strength, were experimentally determined in accreting neutron star systems. Some of the relevant data and the models used to derive useful information from them, are reviewed concentrating mainly on X-ray pulsars. The latest advances in our understanding of the radiation mechanisms and the transfer in the strongly magnetized polar cap regions are discussed.

Meszaros, P.

1981-01-01

363

Intergalactic Star Formation  

Microsoft Academic Search

Star formation in interacting systems may take place in various locations, from the dust--enshrouded core of Ultraluminous Infrared Galaxies to more unusual places such as the debris of colliding galaxies expelled into the intergalactic medium. Determining whether star-formation proceeds in the latter environment, far from the parent galaxies, in a similar way as in spiral disks has motivated the multi--wavelength

Pierre-Alain Duc; Meederic Boquien; Jonathan Braine; Elias Brinks; Ute Lisenfeld; Vassilis Charmandaris

2006-01-01

364

Bubbly Little Star  

NASA Technical Reports Server (NTRS)

In this processed Spitzer Space Telescope image, baby star HH 46/47 can be seen blowing two massive 'bubbles.' The star is 1,140 light-years away from Earth.

The infant star can be seen as a white spot toward the center of the Spitzer image. The two bubbles are shown as hollow elliptical shells of bluish-green material extending from the star. Wisps of green in the image reveal warm molecular hydrogen gas, while the bluish tints are formed by starlight scattered by surrounding dust.

These bubbles formed when powerful jets of gas, traveling at 200 to 300 kilometers per second, or about 120 to 190 miles per second, smashed into the cosmic cloud of gas and dust that surrounds HH 46/47. The red specks at the end of each bubble show the presence of hot sulfur and iron gas where the star's narrow jets are currently crashing head-on into the cosmic cloud's gas and dust material.

Whenever astronomers observe a star, or snap a stellar portrait, through the lens of any telescope, they know that what they are seeing is slightly blurred. To clear up the blurring in Spitzer images, astronomers at the Jet Propulsion Laboratory developed an image processing technique for Spitzer called Hi-Res deconvolution.

This process reduces blurring and makes the image sharper and cleaner, enabling astronomers to see the emissions around forming stars in greater detail. When scientists applied this image processing technique to the Spitzer image of HH 46/47, they were able to see winds from the star and jets of gas that are carving the celestial bubbles.

This infrared image is a three-color composite, with data at 3.6 microns represented in blue, 4.5 and 5.8 microns shown in green, and 24 microns represented as red.

2007-01-01

365

Chaotic Star Birth  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] [figure removed for brevity, see original site] Click on the image for Poster VersionClick on the image for IRAS 4B Inset

Located 1,000 light years from Earth in the constellation Perseus, a reflection nebula called NGC 1333 epitomizes the beautiful chaos of a dense group of stars being born. Most of the visible light from the young stars in this region is obscured by the dense, dusty cloud in which they formed. With NASA's Spitzer Space Telescope, scientists can detect the infrared light from these objects. This allows a look through the dust to gain a more detailed understanding of how stars like our sun begin their lives.

The young stars in NGC 1333 do not form a single cluster, but are split between two sub-groups. One group is to the north near the nebula shown as red in the image. The other group is south, where the features shown in yellow and green abound in the densest part of the natal gas cloud. With the sharp infrared eyes of Spitzer, scientists can detect and characterize the warm and dusty disks of material that surround forming stars. By looking for differences in the disk properties between the two subgroups, they hope to find hints of the star and planet formation history of this region.

The knotty yellow-green features located in the lower portion of the image are glowing shock fronts where jets of material, spewed from extremely young embryonic stars, are plowing into the cold, dense gas nearby. The sheer number of separate jets that appear in this region is unprecedented. This leads scientists to believe that by stirring up the cold gas, the jets may contribute to the eventual dispersal of the gas cloud, preventing more stars from forming in NGC 1333.

In contrast, the upper portion of the image is dominated by the infrared light from warm dust, shown as red.

2005-01-01

366

Cold Hybrid Star Properties  

SciTech Connect

Properties of neutron stars with quark core are investigated. The equation of state of hadronic matter is calculated using Myers and Swiatecki two nucleon interaction within Thomas-Fermi semiclassical approximation (TF). For quark matter we employ The MIT bag model with constant and density dependent bag parameter. With use of the obtained equation of states we have calculated mass-radius relation of such hybrid stars.

Moshfegh, H. R.; Darehmoradi, M.; Mojarrad, M. Ghazanfari [Department of Physics, University of Tehran, North Kargar, P.O.B 14395-547, Tehran (Iran, Islamic Republic of)

2011-10-28

367

Holographic Neutron Stars  

E-print Network

We construct in the context of the AdS/CFT correspondence degenerate composite operators in the conformal field theory that are holographically dual to degenerate stars in anti de Sitter space. We calculate the effect of the gravitational back-reaction using the Tolman-Oppenheimer-Volkoff equations, and determine the "Chandrasekhar limit" beyond which the star undergoes gravitational collapse towards a black hole.

Jan de Boer; Kyriakos Papadodimas; Erik Verlinde

2009-07-16

368

Jars of Stars  

NSDL National Science Digital Library

This math activity uses stars, jars, and scoops to help learners build their estimation and volume skills. As you play, estimate how many scoops of stars it will take to fill a variety of jars. This activity helps learners estimate, predict, reason, strategize, measure volumes, multiply, divide and practice fractions. The activity guide contains a material list, sample questions to ask, literary connections, extensions, and alignment to local and national standards.

Houston, Children'S M.

2014-09-19

369

MMT Hypervelocity Star Survey  

NASA Astrophysics Data System (ADS)

We describe a new survey for unbound hypervelocity stars (HVSs), stars traveling with such extreme velocities that dynamical ejection from a massive black hole is their most likely origin. We investigate the possible contribution of unbound runaway stars, and show that the physical properties of binaries constrain low-mass runaways to bound velocities. We measure radial velocities for HVS candidates with the colors of early A-type and late B-type stars. We report the discovery of six unbound HVSs with velocities and distances exceeding the conservative escape velocity estimate of Kenyon and collaborators. We additionally report four possibly unbound HVSs with velocities and distances exceeding the lower escape velocity estimate of Xue and collaborators. These discoveries increase the number of unbound HVSs by 60%-100%. Other survey objects include 19 newly identified z ~ 2.4 quasars. One of the HVSs may be a horizontal branch star, consistent with the number of evolved HVSs predicted by Galactic center ejection models. Finding more evolved HVSs will one day allow a probe of the low-mass regime of HVSs and will constrain the mass function of stars in the Galactic center.

Brown, Warren R.; Geller, Margaret J.; Kenyon, Scott J.

2009-01-01

370

MMT Hypervelocity Star Survey  

E-print Network

We describe a new survey for unbound hypervelocity stars (HVSs), stars traveling with such extreme velocities that dynamical ejection from a massive black hole (MBH) is their most likely origin. We investigate the possible contribution of unbound runaway stars, and show that the physical properties of binaries constrain low mass runaways to bound velocities. We measure radial velocities for HVS candidates with the colors of early A-type and late B-type stars. We report the discovery of 6 unbound HVSs with velocities and distances exceeding the conservative escape velocity estimate of Kenyon and collaborators. We additionally report 4 possibly unbound HVSs with velocities and distances exceeding the lower escape velocity estimate of Xue and collaborators. These discoveries increase the number of known HVSs by 60%-100%. Other survey objects include 19 newly identified z~2.4 quasars. One of the HVSs may be a horizontal branch star, consistent with the number of evolved HVSs predicted by Galactic center ejection models. Finding more evolved HVSs will one day allow a probe of the low-mass regime of HVSs and will constrain the mass function of stars in the Galactic center.

Warren R. Brown; Margaret J. Geller; Scott J. Kenyon

2008-08-19

371

Quaking Neutron Stars  

NASA Astrophysics Data System (ADS)

Gravitational, magnetic, and superfluid forces can stress the crust of an evolving neutron star. Fracture of the crust under these stresses could affect the star's spin evolution and generate high-energy emission. We study the growth of strain in the crust of a spinning down, magnetized neutron star and examine the initiation of crust cracking (a starquake). In preliminary work in 1998 we studied a homogeneous model of a neutron star. Here we extend this work by considering a more realistic model of a solid, homogeneous crust afloat on a liquid core. In the limits of astrophysical interest, our new results qualitatively agree with those from the simpler model: the stellar crust fractures under shear stress at the rotational equator, matter moves to higher latitudes, and the star's oblateness is reduced. Magnetic stresses favor faults directed toward the magnetic poles. Thus our previous conclusions concerning the star's spin response still hold; namely, asymmetric redistribution of matter excites damped precession, which could ultimately lead to an increase in the spin-down torque. Starquakes associated with glitches could explain the permanent offsets in period derivative observed to follow glitches in at least three pulsars.

Franco, Lucia M.; Link, Bennett; Epstein, Richard I.

2000-11-01

372

Functional Epistatic Interaction between rs6046G>A in F7 and rs5355C>T in SELE Modifies Systolic Blood Pressure Levels  

PubMed Central

Background Although numerous genetic studies have been performed, only 0.9% of blood pressure phenotypic variance has been elucidated. This phenomenon could be partially due to epistatic interactions. Our aim was to identify epistatic interaction(s) associated with blood pressure levels in a pre-planned two-phase approach. Methods and Results In a discovery cohort composed of 3,600 French individuals, we found rs6046A allele in F7 associated with decreased blood pressure levels (P?3.7×10?3) and rs5355T allele in SELE associated with decreased diastolic blood pressure levels (P?=?5×10?3). Both variants interacted in order to influence blood pressure levels (P?0.048). This interaction was replicated with systolic blood pressure in 4,620 additional European individuals (P?=?0.03). Similarly, in this replication cohort, rs6046A was associated with decreased blood pressure levels (P?8.5×10?4). Furthermore, in peripheral blood mononuclear cells of a subsample of 90 supposed healthy individuals, we found rs6046A positively associated with NAMPT mRNA levels (P?9.1×10?5), suggesting an eventual involvement of NAMPT expression in blood pressure regulation. Confirming this hypothesis, further transcriptomic analyses showed that increased NAMPT mRNA levels were positively correlated with ICAM1, SELL, FPR1, DEFA1-3, and LL-37 genes expression (P?5×10?3). The last two mRNA levels were positively associated with systolic blood pressure levels (P?0.01) and explained 4% of its phenotypic variation. Conclusion These findings reveal the importance of epistatic interactions in blood pressure genetics and give new insights for the role of inflammation in its complex regulation. PMID:22815813

El Shamieh, Said; Ndiaye, Ndeye Coumba; Stathopoulou, Maria G.; Murray, Helena A.; Masson, Christine; Lamont, John V.; Fitzgerald, Peter; Benetos, Athanase; Visvikis-Siest, Sophie

2012-01-01

373

A Promoter polymorphism (rs17222919, –1316T\\/G) of ALOX5AP is associated with intracerebral hemorrhage in Korean population  

Microsoft Academic Search

To investigate whether single nucleotide polymorphisms (SNPs) of eicosanoid biosynthesis genes are associated with intracerebral hemorrhage (ICH) and ischemic stroke (IS), seven SNPs in the coding or promoter regions were selected: ALOX12 (rs434473, Asn322Ser), ALOX5 (rs2228064, Thr90Thr), ALOX5AP (rs17222919, ?1316T\\/G), PTGES (rs7872802, ?404A\\/G), PTGIS (rs5628, Leu256Leu), PTGS1 (rs3842788, Gln41Gln) and PTGS2 (rs5275, 3?UTR). A total of 398 control subjects and

Dong Hwan Kim; Woo Yong Ahn; Dong Kwan Kim; Bong Keun Choe; Su Kang Kim; Dae Jean Jo; Jae Young Kim; Joo-Ho Chung; Yong Seol Jeong; Dong Hwan Yun; Seung Don Yoo; Hee-Sang Kim; Hyung Hwan Baik

2011-01-01

374

Genetic Algorithm to Make Persistent Security and Quality of Image in Steganography from RS Analysis  

E-print Network

Retention of secrecy is one of the significant features during communication activity. Steganography is one of the popular methods to achieve secret communication between sender and receiver by hiding message in any form of cover media such as an audio, video, text, images etc. Least significant bit encoding is the simplest encoding method used by many steganography programs to hide secret message in 24bit, 8bit colour images and grayscale images. Steganalysis is a method of detecting secret message hidden in a cover media using steganography. RS steganalysis is one of the most reliable steganalysis which performs statistical analysis of the pixels to successfully detect the hidden message in an image. However, existing steganography method protects the information against RS steganalysis in grey scale images. This paper presents a steganography method using genetic algorithm to protect against the RS attack in colour images. Stego image is divided into number of blocks. Subsequently, with the implementation ...

Nair, T R Gopalakrishnan; S, Manas

2012-01-01

375

P-bRS: A Physarum-Based Routing Scheme for Wireless Sensor Networks  

PubMed Central

Routing in wireless sensor networks (WSNs) is an extremely challenging issue due to the features of WSNs. Inspired by the large and single-celled amoeboid organism, slime mold Physarum polycephalum, we establish a novel selecting next hop model (SNH). Based on this model, we present a novel Physarum-based routing scheme (P-bRS) for WSNs to balance routing efficiency and energy equilibrium. In P-bRS, a sensor node can choose the proper next hop by using SNH which comprehensively considers the distance, energy residue, and location of the next hop. The simulation results show how P-bRS can achieve the effective trade-off between routing efficiency and energy equilibrium compared to two famous algorithms. PMID:24672326

Wei, Wangyang; Zheng, Ruijuan; Wu, Qingtao

2014-01-01

376

The TOR1A Polymorphism rs1182 and the Risk of Spread in Primary Blepharospasm  

PubMed Central

We studied the influence of the rs1182 polymorphism of the TOR1A gene on the risk of dystonia spread in two representative cohorts of patients presenting with primary blepharospasm (BSP), one from Italy and the other from the United States of America. The relationship between rs1182 polymorphism and spread was estimated by Kaplan-Meier survival curves and Cox proportional hazard regression models adjusted by age and sex, age of BSP onset. In both series, patients carrying the T allele (G/T or T/T) in the rs1182 polymorphism were more likely to have dystonia spread as compared with the homozygous carriers of the common G allele. The comparable findings obtained in two independent cohorts support a genetic contribution to BSP spread. PMID:19202559

Defazio, Giovanni; Matarin, Mar; Peckham, Elizabeth L.; Martino, Davide; Valente, Enza M.; Singleton, Andrew; Crawley, Anthony; Aniello, Maria Stella; Brancati, Francesco; Abbruzzese, Giovanni; Girlanda, Paolo; Livrea, Paolo; Hallett, Mark; Berardelli, Alfredo

2014-01-01

377

New and Redesigned pRS Plasmid Shuttle Vectors for Genetic Manipulation of Saccharomycescerevisiae.  

PubMed

We have constructed a set of 42 plasmid shuttle vectors based on the widely used pRS series for use in the budding yeast Saccharomyces cerevisiae and the bacterium Escherichia coli. This set of pRSII plasmids includes new shuttle vectors that can be used with histidine and adenine auxotrophic laboratory yeast strains carrying mutations in the genes HIS2 and ADE1, respectively. Our pRSII plasmids also include updated versions of commonly used pRS plasmids from which common restriction sites that occur within their yeast-selectable biosynthetic marker genes have been removed to increase the availability of unique restriction sites within their polylinker regions. Hence, our pRSII plasmids are a complete set of integrating, centromere and 2? episomal plasmids with the biosynthetic marker genes ADE2, HIS3, TRP1, LEU2, URA3, HIS2, and ADE1 and a standardized selection of at least 16 unique restriction sites in their polylinkers. Additionally, we have expanded the range of drug selection options that can be used for PCR-mediated homologous replacement using pRS plasmid templates by replacing the G418-resistance kanMX4 cassette of pRS400 with MX4 cassettes encoding resistance to phleomycin, hygromycin B, nourseothricin, and bialaphos. Finally, in the process of generating the new plasmids, we have determined several errors in existing publicly available sequences for several commonly used yeast plasmids. Using our updated sequences, we constructed pRS plasmid backbones with a unique restriction site for inserting new markers to facilitate future expansion of the pRS series. PMID:22670222

Chee, Mark K; Haase, Steven B

2012-05-01

378

Association study of interleukin-19 rs2243188 polymorphism with systemic lupus erythematosus in a Chinese population.  

PubMed

The purpose of this study was to evaluate whether a single-nucleotide polymorphism (SNP), rs2243188 of interleukin-19 (IL-19), show significant evidence for association with SLE in a Chinese population. A total of 545 SLE patients and 613 healthy controls were collected in the present study. The genotyping of IL-19 rs2243188 polymorphism was detected by TaqMan allele discrimination assay on the 7300 real time polymorphism chain reaction system. The minor C allele of rs2243188, relative to the major A allele, appeared to have a significantly lower frequency in SLE patients (31.0%) as compared with controls (35.5%) (?(2)?=?5.19, p?=?0.023). We also discovered a statistical significance in the dominant model (CC?+?CA versus AA: OR?=?0.755, 95% CI?=?0.598-0.953, p?=?0.018). However, no significant difference in genotype distribution was found between SLE patients and controls (p?=?0.056). Furthermore, an increased frequency of CC genotype were also detected in lupus nephritis (LN) groups as compared with non-LN groups (p?=?0.024). Besides, the individuals with CC genotype had a 2.201-fold higher risk for the susceptibility to LN than those A allele carriers (AA?+?CA) (p?=?0.006). Unfortunately, the analyses on the relationship of IL-19 rs2243188 with several clinical manifestations of SLE failed to find any significant results. In conclusion, our observations suggested the minor C allele of SNP rs2243188 might be a protective factor for SLE in a Chinese Han population. Moreover, the subgroup analysis highlighted that IL-19 rs2243188 SNP was associated with the susceptibility to LN patients. PMID:24819332

Ni, Jing; Zhang, Min; Zhu, Yan; Chen, Gui-Mei; Liu, Juan; Zhang, Chao; Li, Lian-Ju; Pan, Hai-Feng; Ye, Dong-Qing

2014-09-01

379

Is the COL5A1 rs12722 Gene Polymorphism Associated with Running Economy?  

PubMed Central

The COL5A1 rs12722 polymorphism is considered to be a novel genetic marker for endurance running performance. It has been postulated that COL5A1 rs12722 may influence the elasticity of tendons and the energetic cost of running. To date, there are no experimental data in the literature supporting the relationship between range of motion, running economy, and the COL5A1 rs12722 gene polymorphism. Therefore, the main purpose of the current study was to analyze the influence of the COL5A1rs12722 polymorphism on running economy and range of motion. One hundred and fifty (n?=?150) physically active young men performed the following tests: a) a maximal incremental treadmill test, b) two constant-speed running tests (10 km•h?1 and 12 km•h?1) to determine the running economy, and c) a sit-and-reach test to determine the range of motion. All of the subjects were genotyped for the COL5A1 rs12722 single-nucleotide polymorphism. The genotype frequencies were TT?=?27.9%, CT?=?55.8%, and CC?=?16.3%. There were no significant differences between COL5A1 genotypes for running economy measured at 10 km•h?1 (p?=?0.232) and 12 km•h?1 (p?=?0.259). Similarly, there were no significant differences between COL5A1 genotypes for range of motion (p?=?0.337). These findings suggest that the previous relationship reported between COL5A1 rs12722 genotypes and running endurance performance might not be mediated by the energetic cost of running. PMID:25188268

Bertuzzi, Romulo; Pasqua, Leonardo A.; Bueno, Salomao; Lima-Silva, Adriano Eduardo; Matsuda, Monique; Marquezini, Monica; Saldiva, Paulo H.

2014-01-01

380

Quantitative assessment of the association between MTHFR rs1801131 polymorphism and risk of liver cancer.  

PubMed

Methylenetetrahydrofolate reductase (MTHFR) is one of the most important enzymes for folate metabolism which plays a key role in cell metabolism. MTHFR rs1801131 (A1298C) polymorphism can decrease in vitro MTHFR enzyme activity and has been hypothesized to be associated with liver cancer risk. This study aimed to quantify the strength of the association between MTHFR rs1801131 polymorphism and liver cancer risk by performing a meta-analysis. We searched the PubMed and Wanfang databases for studies relating on the association between MTHFR rs1801131 polymorphism and risk of liver cancer. Seven studies with 2,030 cases of liver cancer and 3,096 controls were finally included into the meta-analysis. Meta-analysis of a total of seven studies showed that the homozygote genotype CC of MTHFR rs1801131 polymorphism was significantly associated with decreased risk of liver cancer (for CC versus AA: odds ratio (OR)?=?0.65, 95% confidence interval (CI) 0.47-0.89, P?=?0.007; for CC versus AA?+?AC: OR?=?0.65, 95% CI 0.48-0.89, P?=?0.006). Subgroup by race showed that the homozygote genotype CC of MTHFR rs1801131 polymorphism was significantly associated with decreased risk of liver cancer in Asians (CC versus AA: OR?=?0.64, 95% CI 0.46-0.90, P?=?0.010; for CC versus AA?+ AC: OR?=?0.63, 95% CI 0.45-0.88, P?=?0.007). However, the association in Caucasians was still unclear owing to the limited data available now. Thus, Asian individuals with the homozygote genotype CC of MTHFR rs1801131 polymorphism are significantly associated with decreased risk of liver cancer. The association in Caucasians needs further studies. PMID:24014085

Liang, Tie-Jun; Liu, Hui; Zhao, Xiao-Qian; Tan, Yan-Rong; Jing, Kai; Qin, Cheng-Yong

2014-01-01

381

Is the COL5A1 rs12722 gene polymorphism associated with running economy?  

PubMed

The COL5A1 rs12722 polymorphism is considered to be a novel genetic marker for endurance running performance. It has been postulated that COL5A1 rs12722 may influence the elasticity of tendons and the energetic cost of running. To date, there are no experimental data in the literature supporting the relationship between range of motion, running economy, and the COL5A1 rs12722 gene polymorphism. Therefore, the main purpose of the current study was to analyze the influence of the COL5A1rs12722 polymorphism on running economy and range of motion. One hundred and fifty (n = 150) physically active young men performed the following tests: a) a maximal incremental treadmill test, b) two constant-speed running tests (10 km · h(-1)) and 12 km · h(-1)) to determine the running economy, and c) a sit-and-reach test to determine the range of motion. All of the subjects were genotyped for the COL5A1 rs12722 single-nucleotide polymorphism. The genotype frequencies were TT = 27.9%, CT = 55.8%, and CC = 16.3%. There were no significant differences between COL5A1 genotypes for running economy measured at 10 km · h(-1) (p = 0.232) and 12 km · h(-1) (p = 0.259). Similarly, there were no significant differences between COL5A1 genotypes for range of motion (p = 0.337). These findings suggest that the previous relationship reported between COL5A1 rs12722 genotypes and running endurance performance might not be mediated by the energetic cost of running. PMID:25188268

Bertuzzi, Rômulo; Pasqua, Leonardo A; Bueno, Salomão; Lima-Silva, Adriano Eduardo; Matsuda, Monique; Marquezini, Monica; Saldiva, Paulo H

2014-01-01

382

Effects of VRK2 (rs2312147) on White Matter Connectivity in Patients with Schizophrenia  

PubMed Central

Recent genome-wide association studies of schizophrenia reported a novel risk variant, rs2312147 at vaccinia-related kinase 2 gene (VRK2), in multiple Asian and European samples. However, its effect on the brain structure in schizophrenia is little known. We analyzed the brain structure of 36 schizophrenia patients and 18 healthy subjects with regard to rs2312147 genotype groups. Brain magnetic resonance scans for gray matter (GM) and white matter (WM) analysis, and genotype analysis for VRK2 rs2312147, were conducted. The Positive and Negative Syndrome Scale and the Digit Symbol Test were assessed for schizophrenia patients. There was no significant difference in either GM volume or WM connectivity with regard to rs2312147 genotype in healthy subjects. In contrast, we found significant differences in the WM connectivity between rs2312147 CC and CT/TT genotype groups of schizophrenia patients. The related brain areas included the splenium of corpus callosum, the left occipital lobe WM, the internal capsule (left anterior limb and right retrolenticular part), the bilateral temporal lobe WM, the left fornix/stria terminalis, the left cingulate gyrus WM, and the left parietal lobe WM. Voxelwise correlation analysis revealed that the Digit Symbol Test scores (age corrected) correlated with the fractional anisotropy in WM tracts that previously showed significant group differences between the CT/TT and CC genotypes in the rs2312147 CT/TT genotype group, while no significant correlation was found in the CC genotype group. Our data may provide evidence for the effect of VRK2 on WM connectivity in patients with schizophrenia. PMID:25079070

Kim, Keun Hyang; Kim, Min-Kyoung; Choi, Tai Kiu; Lee, Sang-Hyuk

2014-01-01

383

Preparation and characterization of free mixed-film of pectin\\/chitosan\\/Eudragit ® RS intended for sigmoidal drug delivery  

Microsoft Academic Search

Polyelectrolyte complex (PEC) film between pectin as an anionic polyelectrolyte and chitosan as a cationic species was prepared by blending two polymer solutions at weight ratio of 2:1 and then solvent casting method. Besides pectin\\/chitosan PEC film, Eudragit® RS, pectin\\/Eudragit® RS and pectin\\/chitosan\\/Eudragit® RS films were also prepared by aforementioned method. In mixed-film formulations, a fixed weight ratio of 1:5

Alireza Ghaffari; Kian Navaee; Mahvash Oskoui; Khosrow Bayati; Morteza Rafiee-Tehrani

2007-01-01

384

pRS4: UN VECTOR DE CLONACIÓN IDÓNEO PARA BACTERIAS ÁCIDO-LÁCTICAS DE USO ALIMENTARIO  

Microsoft Academic Search

The ability of pRS4, a cryptic plasmid from Pediococcus pentosaceus, as a selective cloning vector for lactic acid bacteria has been analysed. The results indicate that pRS4C1, a cloning vector from pRS4 can stably transform Lactobacillus plantarum, Pediococcus acidilactici and P. pentosaceus (three lactic acid bacteria used as starters in the food industry) but it does not transform Enterococcus faecalis

M. C. Rodríguez; M. T. Alegre

385

Human Resources rs_msc83 Page 1 of 10 Date issued: 25-Jul-13 Recruit & Select  

E-print Network

Human Resources ­ rs_msc83 Page 1 of 10 Date issued: 25-Jul-13 Recruit & Select Human Resources the Previous/Next buttons to view the various job vacancies. #12;Human Resources ­ rs_msc83 Page 4 of 10 Date description here to open a PDF version of the full Position Description. #12;Human Resources ­ rs_msc83 Page 5

Hickman, Mark

386

Magnetic fields in A stars besides Ap stars  

NASA Astrophysics Data System (ADS)

I review ongoing efforts to understand the incidence of magnetism in intermediate-mass stars that are different from the magnetic Ap stars. This includes the search for magnetic fields in chemically peculiar stars of the Am and HgMn types as well as in normal A and late-B stars. I discuss different techniques for detecting weak stellar magnetic fields, and present a critical evaluation of recent magnetic detections in non-Ap stars. Special attention is given to the magnetic status of HgMn stars and to the discovery of weak polarization signatures in Sirius and Vega.

Kochukhov, O.

2014-11-01

387

Captured older stars as the reason for apparently prolonged star formation in young star clusters  

E-print Network

The existence of older stars within a young star cluster can be interpreted to imply that star formation occurs on time scales longer than a free-fall time of a pre-cluster cloud core. Here the idea is explored that these older stars are not related to the star formation process forming the young star cluster but rather that the orbits of older field stars are focused by the collapsing pre-cluster cloud core. Two effects appear: The focussing of stellar orbits leads to an enhancement of the density of field stars in the vicinity of the centre of the young star cluster. And due to the time-dependent potential of the forming cluster some of these stars can get bound gravitationally to the cluster. These stars exhibit similar kinematical properties as the newly formed stars and can not be distinguished from them on the basis of radial-velocity or proper-motion surveys. Such contaminations may lead to a wrong apparent star-formation history of a young cluster. In the case of the ONC the theoretical number of gravitationally bound older low-mass field stars agrees with the number of observed older low-mass stars.

Jan Pflamm-Altenburg; Pavel Kroupa

2006-11-16

388

ERG variability in X-linked congenital retinoschisis patients with mutations in the RS1 gene and the diagnostic importance of fundus autofluorescence and OCT  

Microsoft Academic Search

Purpose X-linked congenital retinoschisis (RS) is a relatively frequent retinal dystrophy associated with RS1 gene mutations. A negative electroretinogram (ERG), i.e., a b\\/a wave ratio <1.0 in the standard combined response, is considered a key diagnostic feature of RS. Only a few cases without\\u000a a negative ERG have been reported. Methods This study includes 24 RS patients with RS1 mutations.

Agnes B. Renner; Ulrich Kellner; Britta Fiebig; Elke Cropp; Michael H. Foerster; Bernhard H. F. Weber

2008-01-01

389

R+S^2 theories of gravity without big-bang singularity  

E-print Network

The R+S^2 theories of gravity, where S^2 denotes the quadratic torsion terms, are analyzed under three cases. In the first two cases, the matter fields are described by two different spin fluids. In the third case, the torsion field is assumed to be homogeneous and isotropic in the usual sense. It is found that under all the three cases, the R+S^2 theories may avert the big-bang singularity of the Robertson--Walker universe, with some constraints on the parameters.

Jia-An Lu

2014-04-17

390

E. coli RS2GFP Retention Mechanisms in Laboratory-Scale Fractured Rocks: A Statistical Model  

NASA Astrophysics Data System (ADS)

With billions of gallons of groundwater being withdrawn every day in the US and Canada, it is imperative to understand the mechanisms which jeopardize this resource and the health of those who rely on it. Porous media aquifers have typically been considered to provide significant filtration of particulate matter (e.g. microorganisms), while the fractures in fractured rock aquifers and aquitards are considered to act as contaminant highways allowing a large fraction of pathogens to travel deep into an aquifer relatively quickly. Recent research results indicate that fractured rocks filter out more particulates than typically believed. The goal of the research presented here is to quantify the number of E. coli RS2GFP retained in a single, saturated, laboratory-scale fracture, and to relate the retention of E. coli RS2GFP to the aperture field characteristics and groundwater flow rate. To achieve this goal, physical experiments were conducted at the laboratory-scale to quantify the retention of E. coli RS2GFP through several single, saturated, dolomitic limestone fractures under a range of flow rates. These fractures were also cast with a transparent epoxy in order to visualize the transport mechanisms in the various different aperture fields. The E. coli RS2GFP is tagged with a green-fluorescent protein (GFP) that is used to obtain visualization data when excited by ultraviolet light. A series of experiments was conducted, each of which involved the release of a known number of E. coli RS2GFP at the upstream end of the fracture and measuring the effluent concentration profile. These experiments were conducted using both the natural rock and transparent cast of several different aperture fields, under a range of flow rates. The effects of different aperture field characteristics and flow rates on the retention of E. coli RS2GFP will be determined by conducting a statistical analysis of the retention data under different experimental conditions. The images captured during the visualization experiments will help to draw conclusions regarding the retention mechanisms at play in the fractures. This paper will present a statistical model for the retention of E. coli RS2GFP in fractures as a function of aperture field characteristics and flow rate. The images of the E. coli RS2GFP travelling through the casts, in combination with direct aperture field measurements, will provide insight into the different mechanisms instrumental to particulate retention within the fractures. The results of these experiments will partially bridge the knowledge gap in fractured aquifers by furthering the understanding of transport and retention mechanisms of microorganisms within fractured rocks.

Rodrigues, S. N.; Qu, J.; Dickson, S. E.

2011-12-01

391

Association between hTERT rs2736100 polymorphism and sensitivity to anti-cancer agents  

PubMed Central

Background: The rs2736100 single nucleotide polymorphism (SNP) is located in the intron 2 of human telomerase reverse transcriptase (hTERT) gene. Recent genome-wide association studies (GWAS) have consistently supported the strong association between this SNP and risk for multiple cancers. Given the important role of the hTERT gene and this SNP in cancer biology, we hypothesize that rs2736100 may also confer susceptibility to anti-cancer drug sensitivity. In this study we aim to investigate the correlation between the rs2736100 genotype and the responsiveness to anti-cancer agents in the NCI-60 cancer cell panel. Methods and Materials: The hTERT rs2736100 was genotyped in the NCI-60 cancer cell lines. The relative telomere length (RTL) of each cell line was quantified using real-time PCR. The genotype was then correlated with publically available drug sensitivity data of two agents with telomerase-inhibition activity: Geldanamycin (HSP90 inhibitor) and RHPS4/BRACO19 (G-quadruplex stabilizer) as well as additional 110 commonly used agents with established mechanism of action. The association between rs2736100 and mutation status of TP53 gene was also tested. Results: The C allele of the SNP was significantly correlated with increased sensitivity to RHPS4/BRACO19 with an additive effect (r = ?0.35, p = 0.009) but not with Geldanamycin. The same allele was also significantly associated with sensitivity to antimitotic agents compared to other agents (p = 0.003). The highest correlation was observed between the SNP and paclitaxel (r = ?0.36, p = 0.005). The telomere length was neither associated with rs2736100 nor with sensitivity to anti-cancer agents. The C allele of rs2736100 was significantly associated with increased mutation rate in TP53 gene (p = 0.004). Conclusion: Our data suggested that the cancer risk allele of hTERT rs2736100 polymorphism may also affect the cancer cell response to both TERT inhibitor and anti-mitotic agents, which might be attributed to the elevated telomerase-independent activity of hTERT, as well as the increased risk for TP53 gene mutagenesis conferred by the polymorphism. Detailed mechanisms need to be further investigated. PMID:23986774

Kim, Julie; Jones-Hall, Yava L.; Wei, Rongrong; Myers, Jamie; Qi, Yuan; Knipp, Gregory T.; Liu, Wanqing

2013-01-01

392

Models of symbiotic stars  

NASA Technical Reports Server (NTRS)

One of the most important features of symbiotic stars is the coexistence of a cool spectral component that is apparently very similar to the spectrum of a cool giant, with at least one hot continuum, and emission lines from very different stages of ionization. The cool component dominates the infrared spectrum of S-type symbiotics; it tends to be veiled in this wavelength range by what appears to be excess emission in D-type symbiotics, this excess usually being attributed to circumstellar dust. The hot continuum (or continua) dominates the ultraviolet. X-rays have sometimes also been observed. Another important feature of symbiotic stars that needs to be explained is the variability. Different forms occur, some variability being periodic. This type of variability can, in a few cases, strongly suggest the presence of eclipses of a binary system. One of the most characteristic forms of variability is that characterizing the active phases. This basic form of variation is traditionally associated in the optical with the veiling of the cool spectrum and the disappearance of high-ionization emission lines, the latter progressively appearing (in classical cases, reappearing) later. Such spectral changes recall those of novae, but spectroscopic signatures of the high-ejection velocities observed for novae are not usually detected in symbiotic stars. However, the light curves of the 'symbiotic nova' subclass recall those of novae. We may also mention in this connection that radio observations (or, in a few cases, optical observations) of nebulae indicate ejection from symbiotic stars, with deviations from spherical symmetry. We shall give a historical overview of the proposed models for symbiotic stars and make a critical analysis in the light of the observations of symbiotic stars. We describe the empirical approach to models and use the observational data to diagnose the physical conditions in the symbiotics stars. Finally, we compare the results of this empirical approach with existing models and discuss unresolved problems requiring new observational and theoretical work.

Friedjung, Michael

1993-01-01

393

Life Cycle of Stars  

NASA Technical Reports Server (NTRS)

In this stunning picture of the giant galactic nebula NGC 3603, the crisp resolution of NASA's Hubble Space Telescope captures various stages of the life cycle of stars in one single view. To the upper left of center is the evolved blue supergiant called Sher 25. The star has a unique circumstellar ring of glowing gas that is a galactic twin to the famous ring around the supernova 1987A. The grayish-bluish color of the ring and the bipolar outflows (blobs to the upper right and lower left of the star) indicates the presence of processed (chemically enriched) material. Near the center of the view is a so-called starburst cluster dominated by young, hot Wolf-Rayet stars and early O-type stars. A torrent of ionizing radiation and fast stellar winds from these massive stars has blown a large cavity around the cluster. The most spectacular evidence for the interaction of ionizing radiation with cold molecular-hydrogen cloud material are the giant gaseous pillars to the right of the cluster. These pillars are sculptured by the same physical processes as the famous pillars Hubble photographed in the M16 Eagle Nebula. Dark clouds at the upper right are so-called Bok globules, which are probably in an earlier stage of star formation. To the lower left of the cluster are two compact, tadpole-shaped emission nebulae. Similar structures were found by Hubble in Orion, and have been interpreted as gas and dust evaporation from possibly protoplanetary disks (proplyds). This true-color picture was taken on March 5, 1999 with the Wide Field Planetary Camera 2.

1999-01-01

394

New wheat-rye 5DS-4RS·4RL and 4RS-5DS·5DL translocation lines with powdery mildew resistance.  

PubMed

Powdery mildew is one of the serious diseases of wheat (Triticum aestivum L., 2n = 6 × = 42, genomes AABBDD). Rye (Secale cereale L., 2n = 2 × = 14, genome RR) offers a rich reservoir of powdery mildew resistant genes for wheat breeding program. However, extensive use of these resistant genes may render them susceptible to new pathogen races because of co-evolution of host and pathogen. Therefore, the continuous exploration of new powdery mildew resistant genes is important to wheat breeding program. In the present study, we identified several wheat-rye addition lines from the progeny of T. aestivum L. Mianyang11 × S. cereale L. Kustro, i.e., monosomic addition lines of the rye chromosomes 4R and 6R; a disomic addition line of 6R; and monotelosomic or ditelosomic addition lines of the long arms of rye chromosomes 4R (4RL) and 6R (6RL). All these lines displayed immunity to powdery mildew. Thus, we concluded that both the 4RL and 6RL arms of Kustro contain powdery mildew resistant genes. It is the first time to discover that 4RL arm carries powdery mildew resistant gene. Additionally, wheat lines containing new wheat-rye translocation chromosomes were also obtained: these lines retained a short arm of wheat chromosome 5D (5DS) on which rye chromosome 4R was fused through the short arm 4RS (designated 5DS-4RS·4RL; 4RL stands for the long arm of rye chromosome 4R); or they had an extra short arm of rye chromosome 4R (4RS) that was attached to the short arm of wheat chromosome 5D (5DS) (designated 4RS-5DS·5DL; 5DL stands for the long arm of wheat chromosome 5D). These two translocation chromosomes could be transmitted to next generation stably, and the wheat lines containing 5DS-4RS·4RL chromosome also displayed immunity to powdery mildew. The materials obtained in this study can be used for wheat powdery mildew resistant breeding program. PMID:25163586

Fu, Shulan; Ren, Zhenglong; Chen, Xiaoming; Yan, Benju; Tan, Feiquan; Fu, Tihua; Tang, Zongxiang

2014-11-01

395

SNP rs2073618 of the Osteoprotegerin Gene Is Associated with Diabetic Retinopathy in Slovenian Patients with Type 2 Diabetes  

PubMed Central

Recent studies indicate that osteoprotegerin (OPG) acts as an important regulatory molecule in the vasculature. Also, a strong association was observed between circulation OPG and microvascular complication. By considering the possible role of OPG in diabetic retinopathy (DR) we examined two of the most studied polymorphisms of the OPG genes rs2073618 (located in exon I) and rs3134069 (located in the promoter region) and their relation to DR in Slovenian patients with type 2 diabetes. Logistic regression analysis demonstrated that the carriers of the CC genotype had a 2.2 higher risk for DR than those with either the CG genotype or the GG genotype (codominant model for rs2073618). Furthermore, the combined effect of single nucleotide polymorphisms (SNPs) rs2073618 and rs3134069 on the DR was stronger than that of each SNP alone. The odds ratio (OR) for individuals with CC genotype (rs2073618) and AA genotype (rs3134069) compared with carriers of CG/GG (rs2073618)?+?AA (rs3134069) was 2.54 (95% CI?=?1.26–5.13, P = 0.01). To conclude, these results indicate that SNPs in the OPG gene may be implicated in the pathogenesis of DR. PMID:24228244

Mankoc Ramus, Sara; Kumse, Tina; Globocnik Petrovic, Mojca; Petrovic, Daniel; Cilensek, Ines

2013-01-01

396

How star clusters could survive low star formation efficiencies  

E-print Network

After the stars of a new, embedded star cluster have formed they blow the remaining gas out of the cluster. Especially winds of high mass stars and definitely the on-set of the first super novae can remove the residual gas from a cluster. This leads to a very violent mass-loss and leaves the cluster out of virial equilibrium. Standard models predict that the star formation efficiency (SFE) has to be about 33 per cent for sudden (within one crossing-time of the cluster) gas expulsion to retain some of the stars in a bound cluster. If the efficiency is lower the stars of the cluster disperse completely. Recent observations reveal that in strong star bursts star clusters do not form in isolation but in complexes containing dozens and up to several hundred star clusters (super-clusters). By carrying out numerical experiments we demonstrate that in these environments (i.e. the deeper potential of the star cluster complex and the merging process of the star clusters within these super-clusters) the SFEs could be as low as 20 per cent, leaving a gravitationally bound stellar population. We demonstrate that the merging of the first clusters happens faster than the dissolution time therefore enabling more stars to stay bound within the merger object. Such an object resembles the outer Milky Way globular clusters and the faint fuzzy star clusters recently discovered in NGC 1023.

M. Fellhauer; P. Kroupa

2004-11-29

397

Condensate dark matter stars  

E-print Network

We investigate the structure and stability properties of compact astrophysical objects that may be formed from the Bose-Einstein condensation of dark matter. Once the critical temperature of a boson gas is less than the critical temperature, a Bose-Einstein Condensation process can always take place during the cosmic history of the universe. Therefore we model the dark matter inside the star as a Bose-Einstein condensate. In the condensate dark matter star model, the dark matter equation of state can be described by a polytropic equation of state, with polytropic index equal to one. We derive the basic general relativistic equations describing the equilibrium structure of the condensate dark matter star with spherically symmetric static geometry. The structure equations of the condensate dark matter stars are studied numerically. The critical mass and radius of the dark matter star are given by $M_{crit}\\approx 2(l_a/1fm)^{1/2}(m_{\\chi}/1\\;{\\rm GeV})^{-3/2}M_{\\odot}$ and $R_{crit}\\approx 1.1 \\times 10^6(l_a/1\\;{\\rm fm})^{1/2}(m_{\\chi}/1\\;{\\rm GeV})^{-3/2}$ cm respectively, where $l_a$ and $m_{\\chi}$ are the scattering length and the mass of dark matter particle, respectively.

X. Y. Li; T. Harko; K. S. Cheng

2012-05-14

398

Microlensing Neutron Stars  

E-print Network

We investigate the chances that neutron stars act as the lense in a gravitational microlensing event towards the galactic bulge or a spiral arm. The observation of neutron stars by means of gravitational microlensing would allow the estimation of neutron star masses independently of the property of being a pulsar in a binary system. We estimate the contribution of neutron stars to the optical depth and the lensing rate based on two different models of the pulsar distribution in the galaxy. Since only a small fraction of all neutron stars are pulsars, it is unlikely to find a pulsar that acts as a microlense by chance. A position comparison of known radio pulsars with observed microlensing candidates towards the galactic bulge and spiral arms shows no candidate pair, which is consistent with the theoretical expectation. To improve the probability of microlensing a pulsar, we suggest to search for gravitational microlensing events of known nearby high proper motion pulsars. The pulsar PSR J1932+1059 is a good candidate for an astrometric detection of gravitational lensing.

Dominik J. Schwarz; Dirk Seidel

2002-04-03

399

Holographic Magnetic Star  

E-print Network

A warm fermionic AdS star under a homogeneous magnetic field is explored. We obtain the relativistic Landau levels by using Dirac equation and use the Tolman-Oppenheimer-Volkoff (TOV) equation to study the physical profiles of the star. Bulk properties such as sound speed, adiabatic index, and entropy density within the star are calculated analytically and numerically. Bulk temperature increases the mass limit of the AdS star but external magnetic field has the opposite effect. The results are partially interpreted in terms of the pre-thermalization process of the gauge matter at the AdS boundary after the mass injection. The entropy density is found to demonstrate similar temperature dependence as the magnetic black brane in the AdS in certain limits regardless of the different nature of the bulk and Hawking temperatures. Total entropy of the AdS star is also found to be an increasing function of the bulk temperature and a decreasing function of the magnetic field, similar behaviour to the mass limit. Since both total entropy and mass limit are global quantities, they could provide some hints to the value of entropy and energy of the dual gauge matter before and during the thermalization.

Piyabut Burikham; Tossaporn Chullaphan

2012-03-05

400

Revised Anatomy of Stars  

E-print Network

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

Maurice Dubin; Robert K. Soberman

1997-04-28

401

Definition and empirical structure of the range of stellar chromospheres-coronae across the H-R diagram: Cool stars  

NASA Technical Reports Server (NTRS)

Major advances in our understanding of non-radiative heating and other activity in stars cooler than T sub eff = 10,000K has occured in the last few years. This observational evidence is reviewed and the trends that are now becoming apparent are discussed. The evidence for non-radiatively heated outer atmospheric layers (chromospheres, transition regions, and coronae) in dwarf stars cooler than spectral type A7, in F and G giants, pre-main sequence stars, and close bindary systems is unambiguous, as is the evidence for chromospheres in the K and M giants and supergiants. The existence of non-radiative heating in the outer layers of the A stars remains undetermined despite repeated searches at all wavelengths. Two important trends in the data are the decrease in plasma emission measure with age on the main sequence and decreasing rotational velocity. Variability and atmospheric inhomogeneity are commonly seen, and there is considerable evidence that magnetic fields define the geometry and control the energy balance in the outer atmospheric layers. In addition, the microwave observations imply that non-thermal electrons are confined in coronal magnetic flux tubes in at least the cool dwarfs and RS CVn systems. The chromospheres in the K and M giants and supergiants are geometrically extended, as are the coronae in the RS CVn systems and probably also in other stars.

Linsky, J. L.

1986-01-01

402

Blurred star image processing for star sensors under dynamic conditions.  

PubMed

The precision of star point location is significant to identify the star map and to acquire the aircraft attitude for star sensors. Under dynamic conditions, star images are not only corrupted by various noises, but also blurred due to the angular rate of the star sensor. According to different angular rates under dynamic conditions, a novel method is proposed in this article, which includes a denoising method based on adaptive wavelet threshold and a restoration method based on the large angular rate. The adaptive threshold is adopted for denoising the star image when the angular rate is in the dynamic range. Then, the mathematical model of motion blur is deduced so as to restore the blurred star map due to large angular rate. Simulation results validate the effectiveness of the proposed method, which is suitable for blurred star image processing and practical for attitude determination of satellites under dynamic conditions. PMID:22778666

Zhang, Weina; Quan, Wei; Guo, Lei

2012-01-01

403

Meet the parents: tracing star formation around the ? Ophiuchi star.  

NASA Astrophysics Data System (ADS)

Understanding the mechanisms that trigger the star formation is of crucial importance both in the solar neighborhood and in more distant places. We propose an XMM-Newton observation to study a possible case of triggered star formation event in the nearby star forming region hosting the Rho Ophiuchi star. The suburbs of Rho Oph star are depleted of dust and are marked by a warm dust ring. Inside the ring, few young stellar objects with disks are found. Through X-rays, we aim to have a complete census of the disk-less stars more evolved than those in the main cloud core. Once knowing the sample of stars with and without disk we can estimate the age and assess the evolutionary stage of this part of the cloud and then trace its star formation history.

Pillitteri, Ignazio

2012-10-01

404

The active RS Canum Venaticorum binary II Pegasi. III. Chromospheric emission and flares in 1994-1996  

NASA Astrophysics Data System (ADS)

We analyse observations of the very active RS CVn-type star II Peg carried out simultaneously in chromospheric and photospheric lines in 1994-1996. We describe the correlation of the strength of the He i D3, Ca ii,K and Ca ii 8498 Ä emissions with the spot position on the stellar disk. A two-component structure is suggested in the chromosphere of II Peg, similar to that in the corona: nonvariable component (cool plages) with constant contribution to the line emission and variable, active one (hot plages) showing a growth of its activity during 1994-1996. The active component is related to the spots seen in the photosphere. Two subsequent flares on July 19-23, 1995 were observed in the He i D3 and Ca ii,K and 8498 Ä lines showing strong narrow red-shifted emissions. The development of the flares took a few hours and decay lasted several days. At the maximum of the flaring, in addition to the narrow components, broad blue-shifted emissions appeared in He i and Ca ii,K and in the cores of many strong absorption lines. The broad components are attributed to the process of the explosive evaporation from the low chromosphere. The amount of energy released in different lines is determined. From the radial velocity curve of the He i emission the location of the radiating matter is deduced. It appears to be related to the largest active region which is seen in the stellar image. The flare occurred concurrently with the break of the extended group on two well separated spots. On October 26, 1996 another flare was observed in three spectra, as narrow emissions in the He i and Ca ii,8498 Ä lines but without development in other lines. It probably was a late stage of the flare decay. Based on observations collected at the Nordic Optical Telescope (NOT), La Palma, Spain.

Berdyugina, S. V.; Ilyin, I.; Tuominen, I.

1999-09-01

405

Pre-main sequence stars, emission stars and recent star formation in the Cygnus Region  

E-print Network

The recent star formation history in the Cygnus region is studied using 5 clusters (IC 4996, NGC 6910, Berkeley 87, Biurakan 2 and Berkeley 86). The optical data from the literature are combined with the 2MASS data to identify the pre-main sequence (pre-MS) stars as stars with near IR excess. We identified 93 pre-MS stars and 9 stars with H$_\\alpha$ emission spectra. The identified pre-MS stars are used to estimate the turn-on age of the clusters. The duration of star formation was estimated as the difference between the turn-on and the turn-off age. We find that, NGC 6910 and IC 4996 have been forming stars continuously for the last 6 -- 7 Myr, Berkeley 86 and Biurakan 2 for 5 Myr and Berkeley 87 for the last 2 Myr. This indicates that the Cygnus region has been actively forming stars for the last 7 Myr, depending on the location. 9 emission line stars were identified in 4 clusters, using slit-less spectra (Be 87 - 4 stars; Be 86 - 2 stars, NGC 6910 - 2 stars and IC 4996 - 1 star). The individual spectra were obtained and analysed to estimate stellar as well as disk properties. All the emission stars are in the MS, well below the turn-off, in the core hydrogen burning phase. These stars are likely to be Classical Be (CBe) stars. Thus CBe phenomenon can be found in very young MS stars which are just a few (2 -- 7) Myrs old. This is an indication that CBe phenomenon need not be an evolutionary effect.

Bhavya B; Blesson Mathew; Annapurni Subramaniam

2008-04-09

406

General Relativity&Compact Stars  

SciTech Connect

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

Glendenning, Norman K.

2005-08-16

407

Cool Stars in Hot Places  

E-print Network

During the last three decades, evidence has mounted that star and planet formation is not an isolated process, but is influenced by current and previous generations of stars. Although cool stars form in a range of environments, from isolated globules to rich embedded clusters, the influences of other stars on cool star and planet formation may be most significant in embedded clusters, where hundreds to thousands of cool stars form in close proximity to OB stars. At the cool stars 14 meeting, a splinter session was convened to discuss the role of environment in the formation of cool stars and planetary systems; with an emphasis on the ``hot'' environment found in rich clusters. We review here the basic results, ideas and questions presented at the session. We have organized this contribution into five basic questions: what is the typical environment of cool star formation, what role do hot star play in cool star formation, what role does environment play in planet formation, what is the role of hot star winds and supernovae, and what was the formation environment of the Sun? The intention is to review progress made in addressing each question, and to underscore areas of agreement and contention.

S. T. Megeath; E. Gaidos; J. J. Hester; F. C. Adams; J. Bally; J. -E. Lee; S. Wolk

2007-04-08

408

GuideStar  

NSDL National Science Digital Library

Donors and philanthropists can now more easily compare and monitor organizations to which they may contribute, while nonprofit organizations can perhaps spend less of their resources on fundraising. These are the goals of Philanthropic Research, Inc's GuideStar, a clearinghouse of information on more than 600,000 charities and nonprofit organizations. GuideStar hosts a searchable database, a newsletter, employment and volunteer opportunity listings, and valuable articles in addition to lists of links for both donors and nonprofit organizations. Database information includes brief descriptions of the charities/nonprofits and their programs, funding sources, geographic location(s), and income/asset statements. GuideStar derives its information from 990 tax submissions to the IRS as well as directly from the nonprofit organizations themselves.

409

Spectropolarimetry of cool stars  

E-print Network

In recent years, the development of spectropolarimetric techniques deeply modified our knowledge of stellar magnetism. In the case of solar-type stars, the challenge is to measure a geometrically complex field and determine its evolution over very different time frames. In this article, I summarize some important observational results obtained in this field over the last two decades and detail what they tell us about the dynamo processes that orchestrate the activity of cool stars. I also discuss what we learn from such observations about the ability of magnetic fields to affect the formation and evolution of Sun-like stars. Finally, I evoke promising directions to be explored in the coming years, thanks to the advent of a new generation of instruments specifically designed to progress in this domain.

P. Petit

2007-03-27

410

On the efficiency of field star capture by star clusters  

E-print Network

An exciting recent finding regarding scaling relations among globular clusters is the so-called 'blue tilt': clusters of the blue sub-population follow a trend of redder colour with increasing luminosity. In this paper we evaluate to which extent field star capture over a Hubble time may explain the 'blue tilt'. We perform collisional N-body simulations to quantify the amount of field star capture occuring over a Hubble time to star clusters with 10^3 to 10^6 stars. In the simulations we follow the orbits of field stars passing through a star cluster and calculate the energy change that the field stars experience due to gravitational interaction with cluster stars during one passage through the cluster. The capture condition is that their total energy after the passage is smaller than the gravitational potential at the cluster's tidal radius. By folding this with the fly-by rates of field stars with an assumed space density as in the solar neighbourhood and a range of velocity dispersions, we derive estimates on the mass fraction of captured field stars as a function of environment. We find that integrated over a Hubble time, the ratio between captured field stars and total number of clusters stars is very low (star velocity dispersion sigma=15 km/s. This holds for star clusters in the mass range of both open clusters and globular clusters. We furthermore show that tidal friction has a negligible effect on the energy distribution of field stars after interaction with the cluster. We conclude that field star capture is not a probable mechanism for creating the colour-magnitude trend of metal-poor globular clusters.

Steffen Mieske; Holger Baumgardt

2007-09-10

411

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 starâs 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 monthâs column sheds light on the stars and how astronomers measure distances to these celestial objects.

Riddle, Bob

2009-03-01

412

Characterization and Purification of the Discoidin Domain Containing Protein Retinoschisin (RS1) and Its Interaction with Galactose†  

PubMed Central

RS1, also known as retinoschisin, is an extracellular discoidin domain containing protein that has been implicated in maintaining the cellular organization and synaptic structure of the vertebrate retina. Mutations in the gene encoding RS1 are responsible for X-linked retinoschisis, a retinal degenerative disease characterized by the splitting of the retinal cell layers and visual impairment. To better understand the role of RS1 in retinal cell biology and X-linked retinoschisis, we have studied the interaction of wild-type and mutant RS1 with various carbohydrates coupled to agarose supports. RS1 bound efficiently to galactose-agarose and to a lesser extent lactose-agarose, but not agarose, N-acetylgalactosamine-agarose, N-acetylglucosamine-agarose, mannose-agarose or heparin-agarose. RS1 cysteine mutants (C59S/C223S and C59S/C223S/C40S) which prevent disulfide-linked octamer formation showed little if any binding to galactose-agarose. The disease-causing R141H mutant bound galactose-agarose at levels similar to wild-type RS1, whereas the R141S mutant resulted in a marked reduction in galactose-agarose binding. RS1 bound to galactose-agarose could be effectively displaced by incubation with isopropyl ?-D-1-thiogalactopyranoside (IPTG). This property was used as a basis to develop an efficient purification procedure. Anion exchange and galactose affinity chromatography was used to purify RS1 from the culture media of stably transformed Sf21 insect cells that express and secrete RS1. This cell expression and protein purification method should prove useful in the isolation of RS1 for detailed structure-function studies. PMID:18690710

Dyka, Frank M.; Wu, Winco W.H.; Pfeifer, Tom A.; Molday, Laurie L.; Grigliatti, Thomas A.; Molday, Robert S.

2009-01-01

413

American Urban Star Fest  

NASA Astrophysics Data System (ADS)

Over the last couple of decades New York City implemented, and continues to carry out, several schemes of eradicating luminous graffiti. One result has been the gradual recovery of the natural night sky. By 1994 the normal clear sky transparency over Manhattan deepened to fourth magnitude and has been slowly creeping deeper, until in 2002 it is at magnitude 4 to 4.5. In the spring of 1995, during some lazing on a Manhattan rooftop under a sky full of stars, several New York astronomers hatched the idea of letting the whole people celebrate the renewed starry sky. In due course they, through the Amateur Astronomers Association, engaged the New York City Parks Department and the Urban Park Rangers in an evening of quiet picnicking to enjoy the stars in their natural sky. Thus the Urban Star Fest was born. The event thrilled about 3,000 visitors in Central Park's Sheep Meadow on Saturday 30 September 1995. This year's Fest, the eighth in the series demonstrated the City's upper skyline of stars on Saturday 5 October 2002 to about 2,200 enthused visitors. Although the Fest is always noted as cancelable for inclement weather, so far, it has convened every year, with attendance ranging from 4,000 down to a mere 1,000, this latter being under the smoke plume of the World Trade Center in 2001. Despite this swing in attendance, the American Urban Star Fest is America's largest regularly scheduled public astronomy event. Of course, special occasions, like comets or eclipses, can and do attract far larger interest both in the city and elsewhere. The presentation shows the setup and program of the American Urban Star Fest, to illustrate how the general public can actively become aware of the night sky and see for themselves the result of their very own efforts at removing light pollution--and note where improvement is yet to come.

Pazmino, John

2003-12-01

414

Mechanistic evaluation of the effect of thermal-treating on Eudragit RS matrices  

Microsoft Academic Search

Thermal treatment of acrylic matrices was recently introduced as a tool for prolonging the release of drug. Thermal treatment at temperatures above the Tg of the polymer can decrease drug release rate. In this research we studied the mechanism of the effect of thermal treatment on Eudragit RS matrices. Indomethacin was used as model drug. The results showed that polymer

Shirzad Azarmi; Fatemeh Ghaffari; Raimar Löbenberg; Ali Nokhodchi

2005-01-01

415

Reactor Statics Module, RS-9: Multigroup Diffusion Program Using an Exponential Acceleration Technique.  

ERIC Educational Resources Information Center

The nine Reactor Statics Modules are designed to introduce students to the use of numerical methods and digital computers for calculation of neutron flux distributions in space and energy which are needed to calculate criticality, power distribution, and fuel burnup for both slow neutron and fast neutron fission reactors. The last module, RS-9,…

Macek, Victor C.

416

Nutr55, 81-88], we tested the postprandial 'fiber effect' of the supplementation with RS.  

E-print Network

% as carbohydrates) and the supplemented meal (control + 26 g dry raw potato starch (RPS) providing 22 g RS) at one vitamin A ester was used as a marker for exogenous lipid metabolism. Blood samples were collected every 30 postprandial glycemia and insulinemia. While RPS provided a small fraction of digestible starch (5 g

Paris-Sud XI, Université de

417

The rs1142345 in TPMT Affects the Therapeutic Effect of Traditional Hypoglycemic Herbs in Prediabetes  

PubMed Central

Therapeutic interventions in prediabetes are important in the primary prevention of type 2 diabetes (T2D) and its chronic complications. However, little is known about the pharmacogenetic effect of traditional herbs on prediabetes treatment. A total of 194 impaired glucose tolerance (IGT) subjects were treated with traditional hypoglycemic herbs (Tianqi Jiangtang) for 12 months in this study. DNA samples were genotyped for 184 mutations in 34 genes involved in drug metabolism or transportation. Multinomial logistic regression analysis indicated that rs1142345 (A > G) in the thiopurine S-methyltransferase (TPMT) gene was significantly associated with the hypoglycemic effect of the drug (P = 0.001, FDR P = 0.043). The “G” allele frequencies of rs1142345 in the healthy (subjects reverted from IGT to normal glucose tolerance), maintenance (subjects still had IGT), and deterioration (subjects progressed from IGT to T2D) groups were 0.094, 0.214, and 0.542, respectively. Binary logistic regression analysis indicated that rs1142345 was also significantly associated with the hypoglycemic effect of the drug between the healthy and maintenance groups (P = 0.027, OR = 4.828) and between the healthy and deterioration groups (P = 0.001, OR = 7.811). Therefore, rs1142345 was associated with the clinical effect of traditional hypoglycemic herbs. Results also suggested that TPMT was probably involved in the pharmacological mechanisms of T2D. PMID:23737827

Li, Xi; Lian, Feng-Mei; Guo, Dong; Fan, Lan; Tang, Jie; Peng, Jing-Bo; Deng, Hong-Wen; Liu, Zhao-Qian; Xiao, Xin-Hua; Wang, Yan-Rong; Qu, Ke-Yi; Deng, Sheng; Zhong, Qi; Sha, Yi-Ling; Zhu, Yan; Bai, Yu-Jing; Chen, Xin-Yan; Zhou, Qiang; Zhou, Hong-Hao; Tong, Xiao-Lin; Zhang, Wei

2013-01-01

418

Risk Driven Requirements Specification (RiDeRS) of IT-based Homecare Systems  

E-print Network

, and include patients, their family, nurses, and other health care actors. This means that the concept of riskRisk Driven Requirements Specification (RiDeRS) of IT-based Homecare Systems Mohammad Zarifi Eslami, IT- based care systems can also introduce new types of risks such as those related to availability

Wieringa, Roel

419

Dilatometric studies of the phase transitions of sodium potassium tartrate tetrahydrate (RS)  

Microsoft Academic Search

Temperature dependence of the thermal expansion coefficients of Rochelle salt (RS) crystals for the basic crystallographic directions have been measured in the temperature range from 100 K to 308 K by an air-capacitor dilatometer. Anomalies of thermal expansion coefficients at about 210 K and 153 K have been observed, besides these corresponding to known ferroelectric phase transitions at the temperatures

Marek Wlodarz; Wieslawa Bronowska; Janusz Dziedzic

1988-01-01

420

Design of vancomycin RS-100 nanoparticles in order to increase the intestinal permeability  

PubMed Central

Purpose: The purpose of this work was to preparation of vancomycin (VCM) biodegradable nanoparticles to improve the intestinal permeability, using water-in-oil-in-water (W/O/W) multiple emulsion method. Methods: The vancomycin-loaded nanoparticles were created using double-emulsion solvent evaporation method. Using Eudragit RS100 as a coating material. The prepared nanoparticles were identifyed for their micromeritic and crystallographic properties, drug loading, particle size, drug release, Zeta potential, effective permeability (Peff) and oral fractional absorption. Intestinal permeability of VCM nanoparticles was figured out, in different concentrations using SPIP technique in rats. Results: Particle sizes were between 362 and 499 nm for different compositions of VCM-RS-100 nanoparticles. Entrapment efficiency expansed between 63%-94.76%. The highest entrapment efficiency 94.76% was obtained when the ratio of drug to polymer was 1:3. The in vitro release studies were accomplished in pH 7.4. The results showed that physicochemical properties were impressed by drug to polymer ratio. The FT-IR, XRPD and DSC results ruled out any chemical interaction betweenthe drug and RS-100. Effective intestinal permeability values of VCM nanoparticles in concentrations of 200, 300 and 400 ?g/ml were higher than that of solutions at the same concentrations. Oral fractional absorption was achieved between 0.419-0.767. Conclusion: Our findings suggest that RS-100 nanoparticles could provide a delivery system for VCM, with enhanced intestinal permeability. PMID:24312770

Loveymi, Badir Delf; Jelvehgari, Mitra; Zakeri-Milani, Parvin; Valizadeh, Hadi

2012-01-01

421

The Role of Hierarchy in Learning to Categorize Images Reza Shahbazi (rs689@cornell.edu)  

E-print Network

, a hierarchy is any system of items where no item is superior to itself. Furthermore, there needs to be one is the one advocated by Herbert Simon (1974 ), the pioneering figure of hierarchy theory. While the threeThe Role of Hierarchy in Learning to Categorize Images Reza Shahbazi (rs689@cornell.edu) Uris Hall

Edelman, Shimon

422