Evidence of quiet Sun chromospheric activity related to an emerging small-scale magnetic loop

Aims: We investigate the temporal evolution of magnetic flux emergence in the quiet Sun atmosphere close to disk center. Methods: We combine high-resolution SoHO/MDI magnetograms with TRACE observations taken in the 1216 {\AA} channel in order to analyze the temporal evolution of an emerging small-scale magnetic loop and its traces in the chromosphere. Results: At first place, we find signatures of flux emergence very close to the edge of a supergranular network boundary located at disk center. The new emerging flux appears first in the MDI magnetograms in form of an asymmetric bipolar element, i.e. the patch with negative polarity is roughly two-times weaker than the corresponding patch with opposite polarity. The average values of magnetic flux and magnetic flux densities reach 1.6 x 10^18 Mx, -8.5 x 10^17 Mx, and 55 Mx cm^-2, -30 Mx cm^-2, respectively. The spatial distance between the opposite polarity patches of the emerged feature increases from about 2.5" to 5.0" during the lifetime of the loop which was not longer than 36 min. A more precise lifetime-estimate of the feature was not possible because of a gap in the temporal sequence of the MDI magnetograms. The chromospheric response to the emerged magnetic dipole occurs ~ 9 minutes later with respect to the photospheric magnetograms. It consists of a quasi-periodic sequence of time-localized brightenings visible in the 1216 {\AA} TRACE channel apparent for ~ 14 minutes and being co-spatial with the axis connecting the two patches of opposite magnetic polarity. Conclusions: We identify the observed event as a small-scale magnetic loop emerging at photospheric layers and subsequently rising up to the chromosphere. We discuss the possibility that the fluctuations detected in the chromospheric emission probably reflect magnetic field oscillations which propagate to the chromosphere in form of waves.Comment: 6 pages, 4 figures, 1 table, Astronomy and Astrophysics, in pres

Formation of a penumbra in a decaying sunspot

Context : Penumbrae are an important characteristic of sunspots, whose formation is intricately related to the nature of sub-photospheric magnetic fields. Aims : We study the formation of a penumbra in a decaying sunspot and compare its properties with those seen during the development of a proto-spot. Methods : High-resolution spectropolarimetric observations of active region NOAA 11283 were obtained from the spectro-polarimeter on board Hinode. These were complemented with full-disk filtergrams of continuum intensity, line-of-sight magnetograms, and dopplergrams from the Helioseismic and Magnetic Imager at high cadence. Results : The formation of a penumbra in the decaying sunspot occurs after the coalescence of the sunspot with a magnetic fragment/pore, which initially formed in the quiet Sun close to an emerging flux region. At first, a smaller set of penumbral filaments develop near the location of the merger with very bright penumbral grains with intensities of 1.2 I_QS, upflows of 4 km/s, and a lifetime of 10 hr. During the decay of these filaments, a larger segment of a penumbra forms at the location of the coalescence. These new filaments are characterized by nearly supersonic downflows of 6.5 km/s that change to a regular Evershed flow nearly 3 hr later. Conclusions : The coalescence of the pore with the decaying sunspot provided sufficient magnetic flux for the penumbra to form in the sunspot. The emerging flux region could have played a decisive role in this process because the formation occurred at the location of the merger and not on the opposite side of the sunspot.Comment: Accepted for publication in A&A Letters, 6 pages, 4 figure

Application of artificial neural networks to solar infrared Stokes spectra

Inthis paper we have for the first time applied the new Stokes inversion approach of using artificial neural networks to measured Stokes data of a solar pore. We have demonstrated that this method is capable to produce the same results as other conventional methods, but at a much faster speed

Thin layer shearing of a highly plastic clay

International audienceShearing tests with a thin layer of clay between filter slabs render possible large and cyclic deformations with drainage. In the pressure range of 100 kPa they serve to validated visco-hypoplastic constitutive relations. This theory is also confirmed by tests with up to 14 MPa and super-imposed anti-plane cycles. After this kind of seismic disturbance the clay stabilizes if the ratio of permanent stresses is undercritical. Otherwise a spontaneous acceleration occurs after a delay. This could help to understand critical phenomena with clay smears in faults

The three-dimensional structure of sunspots II. The moat flow at two different heights

Many sunspots are surrounded by a radial outflow called the moat flow. We investigate the moat flow at two different heights of the solar atmosphere for a sunspot whose magnetic properties were reported in the first paper of this series. We use two simultaneous time series taken with the Transition Region And Coronal Explorer (TRACE) in white light and in the UV at 170 nm. The field-of-view is centered on the small sunspot NOAA 10886 located near disk center. Horizontal velocities are derived by applying two different local correlation tracking techniques. Outflows are found everywhere in the moat. In the inner moat, the velocities from the UV series are larger than those from white light, whereas in the outer part of the moat we find the converse result. The results imply that the white light velocities represent a general outflow of the quiet sun plasma in the moat, while UV velocities are dominated by small bright points that move faster than the general plasma flow.Comment: Manuscript accepted by Astronomy & Astrophysic

Individualising drug dispensaries in a university hospital

BACKGROUND: In hospitals and other healthcare institutions drugs are routinely stored in designated satellite areas on the wards. Often ad hoc decisions are made by clinicians and nurses regarding drug type and quantity to be stored. As a result the number of different drugs and drug packages in storage tends to increase, which may lead to inefficient drug handling and become a potential risk factor in the medication control process. Based on an extended analysis of drug inventories on three different wards it was hypothesized that a ward-individualised formulary (WIF) can halve the number of different drugs and drug packages in a drug dispensary and hence reduce bound capital, money lost through expired drugs, and facilitate safer drug handling. The interdisciplinary intervention described here took place on three 40-bed wards in a 700-bed university hospital housing patients in general internal medicine, haematology, nephrology and oncology. METHODS: A WIF was defined by including all drugs from the hospital formulary ordered at least three times in the past six months. A pharmacist, a nurse and a clinician reviewed the inclusion list of drugs and clinicians were strongly encouraged to prescribe drugs primarily from the WIF. Drugs excluded from the WIF were removed from the drug dispensaries and the number of included drug packages stored in the remote dispensaries was reduced according to their order history. Drug inventory on the wards was monitored from February 2004 to April 2006. RESULTS: The initial drug dispensary inventories on wards A, B and C consisted of 2031, 1667 and 1536 packages with 943, 897 and 831 different drugs valued at h 83 931, h 44 590 and h 57 285. respectively. After adjusting the drug dispensaries according to the WIF drug dispensary inventories on wards A, B and C consisted of 808 (-60%), 600 (-64%) and 485 (-68%) packages with 415 (-56%), 334 (-63%) and 376 (-55%) different drugs valued euro 28 012 (-67%), euro 10 381 (-77%) an euro 17 898 (-69%). The overall reductions the number of packages, the different drugs and the drug value were comparable (<50%) and remained low during the entire observation time (A: 18 months, B: 13 months, C: 8 months). CONCLUSION: Rearranging dispensaries by individualizing the drug inventory according to the needs of the ward by introducing a WIF is a valuable means to significantly (<50%) reduce [1] the number of drug packages, [2] the number of different drugs stored and [3] the capital bound drugs. The positive effects of the WIF are supported by the interdisciplinary interaction of the different professional groups involved in the medication process. The leaner drug dispensaries offer optimal basic conditions for introducing new IT-based systems to further increase the safety of the medication process

Temporal evolution of arch filaments as seen in He I 10830 \r{A}

We study the evolution of an arch filament system (AFS) and of its individual arch filaments to learn about the processes occurring in them. We observed the AFS at the GREGOR solar telescope on Tenerife at high cadence with the very fast spectroscopic mode of the GREGOR Infrared Spectrograph (GRIS) in the He I 10830 \AA\ spectral range. The He I triplet profiles were fitted with analytic functions to infer line-of-sight (LOS) velocities to follow plasma motions within the AFS. We tracked the temporal evolution of an individual arch filament over its entire lifetime, as seen in the He I 10830 \AA\ triplet. The arch filament expanded in height and extended in length from 13" to 21". The lifetime of this arch filament is about 30 min. About 11 min after the arch filament is seen in He I, the loop top starts to rise with an average Doppler velocity of 6 km/s. Only two minutes later, plasma drains down with supersonic velocities towards the footpoints reaching a peak velocity of up to 40 km/s in the chromosphere. The temporal evolution of He I 10830 \AA\ profiles near the leading pore showed almost ubiquitous dual red components of the He I triplet, indicating strong downflows, along with material nearly at rest within the same resolution element during the whole observing time. We followed the arch filament as it carried plasma during its rise from the photosphere to the corona. The material then drained toward the photosphere, reaching supersonic velocities, along the legs of the arch filament. Our observational results support theoretical AFS models and aids in improving future models.Comment: Accepted for publication in Astronomy & Astrophysics, 12 pages, 15 figures, 1 online movi

Differential rotation measurement of soft X-Ray corona

The aim of this paper is to study the latitudinal variation in the solar rotation in soft X-ray corona. The time series bins are formed on different latitude regions of the solar full disk (SFD) images that extend from 80 degree South to 80 degree North. These SFD images are obtained with the soft X-ray telescope (SXT) on board the Yohkoh solar observatory. The autocorrelation analyses are performed with the time series that track the SXR flux modulations in the solar corona. Then for each year, extending from 1992 to 2001, we obtain the coronal sidereal rotation rate as a function of the latitude. The present analysis from SXR radiation reveals that; (i) the equatorial rotation rate of the corona is comparable to the rotation rate of the photosphere and the chromosphere, (ii) the differential profile with respect to the latitude varies throughout the period of the study; it is more in the year 1999 and least in 1994 and (iii) the equatorial rotation period varies systematically with sunspot numbers and indicates its dependence on the phases of the solar activity cycle.Comment: 9 Pages, 4 Figures, Accepted for Publication in MNRA

Astrophysics Evidence of quiet-Sun chromospheric activity related to an emerging small-scale magnetic loop

ABSTRACT Aims. We investigate the temporal evolution of magnetic flux emergence in the quiet-Sun atmosphere close to disk center. Methods. We combined high-resolution SoHO/MDI magnetograms with TRACE observations taken in the 1216 Å channel to analyze the temporal evolution of an emerging small-scale magnetic loop and its traces in the chromosphere. Results. We find signatures of flux emergence very close to the edge of a supergranular network boundary located at disk center. The new emerging flux appeared first in the MDI magnetograms in form of an asymmetric bipolar element, i.e., the patch with negative polarity is roughly twice as weak as the corresponding patch with opposite polarity. The average values of magnetic flux and magnetic flux densities reached 1.6 × 10 18 Mx, −8.5 × 10 17 Mx, and 55 Mx cm −2 , -30 Mx cm −2 , respectively. The spatial distance between the opposite polarity patches of the emerged feature increased from about 2. 5 to 5. 0 during the lifetime of the loop, which was 36 min. A more precise lifetime-estimate of the feature was not possible because of a gap in the temporal sequence of the MDI magnetograms. The chromospheric response to the emerged magnetic dipole occurred ∼9 min later than in the photospheric magnetograms. It consisted of a quasi-periodic sequence of time-localized brightenings visible in the 1216 Å TRACE channel for ∼14 min that were co-spatial with the axis connecting the two patches of opposite magnetic polarity. Conclusions. We identify the observed event as a small-scale magnetic loop emerging at photospheric layers that subsequently rose to the chromosphere. We discuss the possibility that the fluctuations detected in the chromospheric emission probably reflect magneticfield oscillations which propagate to the chromosphere in the form of waves