Bioavailability and feasibility of subcutaneous 5-fluorouracil

Borner, MM; Kneer, Johannes; Crevoisier, C; Brunner, K. W.; Cerny, T

doi:10.1038/bjc.1993.382

Cited by 12 publications

(9 citation statements)

References 13 publications

(19 reference statements)

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“…Küveler & Wiehr (1985) did not find a sharp change in the Evershed flow at the penumbral boundary. Dialetis et al (1985), Alissandrakis et al (1988), and Börner & Kneer (1992) confirmed this result. Giovanelli & Jones (1982) reported magnetogram observations of diffuse, almost horizontal magnetic field surrounding two spots at moderate heliocentric angles.…”

Section: Introductionsupporting

confidence: 79%

The flow field in the sunspot canopy

Rezaei

Schlichenmaier

Beck

et al. 2006

A&A

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Aims. We investigate the flow field in the sunspot canopy using simultaneous Stokes vector spectropolarimetry of three sunspots (θ = 27• , 50• , 75• ) and their surroundings in visible (630.15 and 630.25 nm) and near infrared (1564.8 and 1565.2 nm) neutral iron lines. Methods. To calibrate the Doppler shifts, we compare an absolute velocity calibration using the telluric O 2 -line at 630.20 nm and a relative velocity calibration using the Doppler shift of Stokes V profiles in the umbra under the assumption that the umbra is at rest. Both methods yield the same result within the calibration uncertainties (∼150 m s −1 ). We study the radial dependence of Stokes V profiles in the directions of disk center and limb side. Results. Maps of Stokes V profile shifts, polarity, amplitude asymmetry, field strength and magnetic field azimuth provide strong evidence for the presence of a magnetic canopy and for the existence of a radial outflow in the canopy. Conclusions. Our findings indicate that the Evershed flow does not cease abruptly at the white-light spot boundary, but that at least a part of the penumbral Evershed flow continues into the magnetic canopy.Key words. Sun: photosphere -Sun: sunspots -Sun: magnetic fields IntroductionFrom the pioneering work of Evershed (1909), we know that there is a flow field in the sunspot penumbra, which leads to a line shift and line asymmetry. For sunspots outside the disk center, it manifests in blue shifted spectral lines in the center side and red shifted spectral lines in the limb side. The penumbral fine structure has a close relation with the Evershed flow. It is generally accepted that the flow channels are more horizontal than the background field (Solanki 2003). Because spectropolarimetric data has lower spatial resolution than narrow band magnetograms, many questions regarding both the Evershed flow and the fine structure of the penumbra have remained (e.g. Solanki 2003; Bellot Rubio 2004). There are also controversial arguments about the continuation of the Evershed flow outside the sunspot.Brekke & Maltby (1963) studied horizontal variations of the Evershed flow. Investigating 2500 sunspot spectra, they reported that at the outer penumbral boundary "the velocity falls abruptly to zero". Wiehr et al. (1986) observed a sharp decrease of the Evershed effect and magnetic field at the visible boundary of sunspots. Using only Stokes I spectra, they argued that line-core shifts and line asymmetries are "strongly" limited to the continuum boundary of sunspots. Wiehr & Balthasar (1989), Schröter et al. (1989 and Title et al. (1993) confirmed the result of Brekke & Maltby (1963). Wiehr (1996) renewed his argument that the Stokes I profile asymmetries of Ni I 543.6 nm (g = 0.5) and Fe I 543.5 nm (g = 0) "disappear" within less than one arcsec from the penumbral border. Hirzberger & Kneer (2001) observed two sunspots at heliocentric angles of 31• and 20• ; they reported a sharp decrease of the Evershed flow (intensity profile asymmetry) at the penumbral boundary, using Sto...

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Section: Introductionsupporting

confidence: 79%

The flow field in the sunspot canopy

Rezaei

Schlichenmaier

Beck

et al. 2006

A&A

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“…This downflow may be related to the isolated downflow seen just outside a sunspot by Börner & Kneer (1992) and may partly explain why the Evershed velocity in the superpenumbra does not increase with distance from the sunspot, although the increasing canopy height implies that the mass flux must decrease (Solanki et al 1994(Solanki et al , 1999: a part of the mass drains down into MMFs. The rather low MMF downflow velocities suggest that the field in the MMF pairs is heavily inclined to the vertical.…”

Section: Discussionmentioning

confidence: 99%

The velocity structure of moving magnetic feature pairs around sunspots: support for the U-loop model

Zhang

Solanki

Woch

et al. 2007

A&A

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Context. Moving magnetic feature (MMF) pairs are among the most significant fine-scale structures around sunspots. Several models have been proposed to interpret the origin and evolution of MMF pairs. These models provide important clues to understanding MMF pairs. Aims. We present an analysis of the velocity structure of MMF pairs in order to put further constrains on the MMF models. , and on average, the velocity of an MMF pair decreases significantly (from 0.6 km s −1 to 0.35 km s −1 ) with increasing distance from the MMF's birth place. In contrast, the decrease of the average velocity is far less obvious from 0.5 km s −1 to 0.4 km s −1 with increasing distance from the sunspot. This result suggests that the change in MMF flow speed does not reflect the radial structure of the moat flow, but rather is intrinsic to the evolution of the MMF pairs. This result is also in agreement with the U-loop model of MMF pairs. We also find that properties of MMF pairs, most strikingly the lifetime, depend on the evolution stages of the parent sunspot. The mean lifetimes of MMF pairs in ARs 9575 and 0330 are 0.7 h and 1.6 h, respectively, which is considerably shorter than the 4 h lifetime previously found for AR 8375.

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“…Wiehr & Balthasar 1989;Title et al 1993;Wiehr & Degenhardt 1994;Balthasar et al 1996) have found an abrupt drop of the flow velocity whereas others (Alissandrakis et al 1988;Börner & Kneer 1992;Rimmele 1995b) have found a continuation of the flow beyond the outer penumbral boundary. Solanki et al (1994) have found a sharp drop of the Evershed flow in the low photosphere but a continuation of it in the higher so-called superpenumbral canopy.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, observational results of e.g. Stellmacher & Wiehr (1980), Ichimoto (1987) and Balthasar et al (1997) show an increase of the line asymmetry but a decrease of the line core shifts the higher the lines are formed and even an inversion of the flow direction in the uppermost regions of the photosphere and in the chromosphere (Alissandrakis et al 1988;Börner & Kneer 1992;Rimmele 1995a). A widely accepted explanation for this result is that the Evershed flow is concentrated in dark almost horizontal flow channels (inclination angle φ = 6…”

Section: Introductionmentioning

confidence: 99%

2D-spectroscopy of the Evershed flow in sunspots

Hirzberger

Kneer

2001

A&A

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Abstract. The radial variation of the Evershed flow in two small sunspots (NOAA 8737 and NOAA 9145) is studied by means of two-dimensional spectrograms of high spatial resolution. We find a systematic decrease of the flow velocity with photospheric height and a shift of the velocity maximum towards larger penumbral radii in higher layers but no clear correlation between flow velocity and continuum intensity. At the outer penumbral boundaries the Evershed flow ceases abruptly and even downward directed flow velocities in the deepest probed photospheric layers were found. Furthermore, granules adjacent to the penumbral boundary show a systematic redshift of their spot-side parts which is attributed to fast, eventually supersonic, downflows between them and the penumbral boundary.

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Bioavailability and feasibility of subcutaneous 5-fluorouracil

Cited by 12 publications

References 13 publications

The flow field in the sunspot canopy

The flow field in the sunspot canopy

The velocity structure of moving magnetic feature pairs around sunspots: support for the U-loop model

2D-spectroscopy of the Evershed flow in sunspots

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