Time delays in quasi-periodic pulsations observed during the X2.2 solar flare on 2011 February 15

We report observations of quasi-periodic pulsations (QPPs) during the X2.2 flare of 2011 February 15, observed simultaneously in several wavebands. We focus on fluctuations on time scale 1-30 s and find different time lags between different wavebands. During the impulsive phase, the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) channels in the range 25-100 keV lead all the other channels. They are followed by the Nobeyama RadioPolarimeters at 9 and 17 GHz and the Extreme Ultra-Violet (EUV) channels of the Euv SpectroPhotometer (ESP) onboard the Solar Dynamic Observatory (SDO). The Zirconium and Aluminum filter channels of the Large Yield Radiometer (LYRA) onboard the Project for On-Board Autonomy (PROBA2) satellite and the SXR channel of ESP follow. The largest lags occur in observations from the Geostationary Operational Environmental Satellite (GOES), where the channel at 1-8 {\AA} leads the 0.5-4 {\AA} channel by several seconds. The time lags between the first and last channels is up to 9 s. We identified at least two distinct time intervals during the flare impulsive phase, during which the QPPs were associated with two different sources in the Nobeyama RadioHeliograph at 17 GHz. The radio as well as the hard X-ray channels showed different lags during these two intervals. To our knowledge, this is the first time that time lags are reported between EUV and SXR fluctuations on these time scales. We discuss possible emission mechanisms and interpretations, including flare electron trapping

Invasive mechanical ventilation in cancer patients: prior non-invasive ventilation is a poor prognostic factor

info:eu-repo/semantics/publishe

Hinode/EIS observations of propagating low-frequency slow magnetoacoustic waves in fan-like coronal loops

We report the first observation of multiple-periodic propagating disturbances along a fan-like coronal structure simultaneously detected in both intensity and Doppler shift in the Fe XII 195 A line with the EUV Imaging Spectrometer (EIS) onboard Hinode. A new application of coronal seismology is provided based on this observation. We analyzed the EIS sit-and-stare mode observation of oscillations using the running difference and wavelet techniques. Two harmonics with periods of 12 and 25 min are detected. We measured the Doppler shift amplitude of 1-2 km/s, the relative intensity amplitude of 3%-5% and the apparent propagation speed of 100-120 km/s. The amplitude relationship between intensity and Doppler shift oscillations provides convincing evidence that these propagating features are a manifestation of slow magnetoacoustic waves. Detection lengths (over which the waves are visible) of the 25 min wave are about 70-90 Mm, much longer than those of the 5 min wave previously detected by TRACE. This difference may be explained by the dependence of damping length on the wave period for thermal conduction. Based on a linear wave theory, we derive an inclination of the magnetic field to the line-of-sight about 59$\pm$8 deg, a true propagation speed of 128$\pm$25 km/s and a temperature of 0.7$\pm$0.3 MK near the loop's footpoint from our measurements.Comment: 4 pages and 4 figures, with 3 online figures and 1 online table; Astron & Astrophys Letter, in pres

Observational properties of a kink unstable coronal loop

Aims. Previous work on the dynamics of the kink instability has concentrated on the evolution of the magnetic field and associated current sheets. Here we aim to determine the observational consequences of the kink instability in short coronal loops, particularly what images TRACE would record of such an instability. This paper concentrates on the internal m = 1 mode where the kink structure of the instability may not be apparent from the global field shape. This is most relevant to the observation of active region brightenings and coronal bright points. Methods. An existing fluid code was modified to include the TRACE temperature response function in order to calculate temporally and spatially averaged, line of sight images in the 171, 195 and 284 Å band passes for straight, kink unstable flux tubes. Results. Two new fluid effects of the kink instability are discovered: the circular enhancement of the density at the foot points and the appearance of a low density band running across the flux tube. The second of these effects is shown to be imagable by TRACE and hence would be a good candidate observational signature for an internal m = 1 kink unstable loop

An International Urogynecological Association (IUGA)/International Continence Society (ICS) joint report on the terminology for the conservative and nonpharmacological management of female pelvic floor dysfunction

There has been an increasing need for the terminology on the conservative management of female pelvic floor dysfunction to be collated in a clinically based consensus report.This Report combines the input of members and elected nominees of the Standardization and Terminology Committees of two International Organizations, the International Urogynecological Association (IUGA) and the International Continence Society (ICS), assisted at intervals by many external referees. An extensive process of nine rounds of internal and external review was developed to exhaustively examine each definition, with decision-making by collective opinion (consensus). Before opening up for comments on the webpages of ICS and IUGA, five experts from physiotherapy, neurology, urology, urogynecology, and nursing were invited to comment on the paper.A Terminology Report on the conservative management of female pelvic floor dysfunction, encompassing over 200 separate definitions, has been developed. It is clinically based, with the most common symptoms, signs, assessments, diagnoses, and treatments defined. Clarity and ease of use have been key aims to make it interpretable by practitioners and trainees in all the different specialty groups involved in female pelvic floor dysfunction. Ongoing review is not only anticipated, but will be required to keep the document updated and as widely acceptable as possible.A consensus-based terminology report for the conservative management of female pelvic floor dysfunction has been produced, aimed at being a significant aid to clinical practice and a stimulus for research

Determination of the radial profile of the photoelastic coefficient of plastic optical fibers

We developed a measurement method to determine the radial distribution of the photoelastic coefficient C(r) in step-index polymer optical fibers (POFs). The method is based on the measurement of the retardance profile of a transversally illuminated fiber for increasing tensile load. The radial profile C(r) is obtained from the inverse Abel transform of this retardance profile. We measured polymer fibers from different manufacturers. The radial profile of the photoelastic constant can considerable vary depending on the type and treatment of POFs, even when made from similar materials, which leads to the conclusion that the photoelastic constant should be characterized for each different type of POF. The impact of annealing the fiber samples on C(r) is also addressed

The SWAP EUV Imaging Telescope Part I: Instrument Overview and Pre-Flight Testing

The Sun Watcher with Active Pixels and Image Processing (SWAP) is an EUV solar telescope on board ESA's Project for Onboard Autonomy 2 (PROBA2) mission launched on 2 November 2009. SWAP has a spectral bandpass centered on 17.4 nm and provides images of the low solar corona over a 54x54 arcmin field-of-view with 3.2 arcsec pixels and an imaging cadence of about two minutes. SWAP is designed to monitor all space-weather-relevant events and features in the low solar corona. Given the limited resources of the PROBA2 microsatellite, the SWAP telescope is designed with various innovative technologies, including an off-axis optical design and a CMOS-APS detector. This article provides reference documentation for users of the SWAP image data.Comment: 26 pages, 9 figures, 1 movi

Energy Distribution of Micro-events in the Quiet Solar Corona

Recent imaging observations of EUV line emissions have shown evidence for frequent flare-like events in a majority of the pixels in quiet regions of the solar corona. The changes in coronal emission measure indicate impulsive heating of new material to coronal temperatures. These heating or evaporation events are candidate signatures of "nanoflares" or "microflares" proposed to interpret the high temperature and the very existence of the corona. The energy distribution of these micro-events reported in the literature differ widely, and so do the estimates of their total energy input into the corona. Here we analyze the assumptions of the different methods, compare them by using the same data set and discuss their results. We also estimate the different forms of energy input and output, keeping in mind that the observed brightenings are most likely secondary phenomena. A rough estimate of the energy input observed by EIT on the SoHO satellite is of the order of 10% of the total radiative output in the same region. It is considerably smaller for the two reported TRACE observations. The discrepancy can be explained partially by different thresholds for flare detection. There is agreement on the slope and the absolute value of the distribution if the same method were used and a numerical error corrected. The extrapolation of the power law to unobserved energies that are many orders of magnitude smaller remains questionable. Nevertheless, these micro-events and unresolved smaller events are currently the best source of information on the heating process of the corona

Coronal Alfvén speed determination : consistency between seismology using AIA/SDO transverse loop oscillations and magnetic extrapolation

Two transversely oscillating coronal loops are investigated in detail during a flare on the 6th September 2011 using data from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO).We compare two independent methods to determine the Alfvén speed inside these loops. Through the period of oscillation and loop length information about the Alfvén speed inside each loop is deduced seismologically. This is compared with the Alfvén speed profiles deduced from magnetic extrapolation and spectral methods using AIA bandpass. We find that for both loops the two methods are consistent. Also, we find that the average Alfvén speed based on loop travel time is not necessarily a good measure to compare with the seismological result, which explains earlier reported discrepancies. Instead, the effect of density and magnetic stratification on the wave mode has to be taken into account. We discuss the implications of combining seismological, extrapolation and spectral methods in deducing the physical properties of coronal loops

Preliminary Results on Irradiance Measurements from Lyra and Swap

International audienceThe first and preliminary results of the photometry of Large Yield Radiometer (LYRA) and Sun Watcher using Active Pixel system detector and Image Processing (SWAP) onboard PROBA2 are presented in this paper. To study the day-to-day variations of LYRA irradiance, we have compared the LYRA irradiance values (observed Sun as a star) measured in Aluminum filter channel (171 Å-500 Å) with spatially resolved full-disk integrated intensity values measured with SWAP (174 Å) and Ca II K 1 Å index values (ground-based observations from NSO/Sac Peak) for the period from 01 April 2010 to 15 Mar 2011. We found that there is a good correlation between these parameters. This indicates that the spatial resolution of SWAP complements the high temporal resolution of LYRA. Hence SWAP can be considered as an additional radiometric channel. Also the K emission index is the integrated intensity (or flux) over a 1 Å band centered on the K line and is proportional to the total emission from the chromosphere; this comparison clearly explains that the LYRA irradiance variations are due to the various magnetic features, which are contributing significantly. In addition to this we have made an attempt to segregate coronal features from full-disk SWAP images. This will help to understand and determine the actual contribution of the individual coronal feature to LYRA irradiance variations