Instrument and data analysis challenges for imaging spectropolarimetry

The next generation of solar telescopes will enable us to resolve the fundamental scales of the solar atmosphere, i.e., the pressure scale height and the photon mean free path. High-resolution observations of small-scale structures with sizes down to 50 km require complex post-focus instruments, which employ adaptive optics (AO) and benefit from advanced image restoration techniques. The GREGOR Fabry-Perot Interferometer (GFPI) will serve as an example of such an instrument to illustrate the challenges that are to be expected in instrumentation and data analysis with the next generation of solar telescopes.Comment: 4 pages, 1 figure, accepted for publication in Astronomische Nachrichten/AN, special issue of the 1st EAST-ATST Workshop: "Science with large solar telescopes" in Freiburg, Germany, October 14-16, 200

Simulation algorithm to model the visible tunable filter for the Daniel K. Inouye Solar Telescope

Journal of astronomical telescopes, instruments, and systems : JATIS 3 (2017), Nr. 0

Effect of ischemia on localization of heat shock protein 25 in kidney

Effect of ischemia on localization of heat shock protein 25 in kidney. The effects of renal ischemia on the intracellular distribution of the low-molecular weight heat shock protein (HSP)25 were examined using immunofluorescence microscopy. In all kidney zones, ischemia decreased HSP25 in the supernatant of the tissue homogenates and increased it in the pellet fraction (containing mainly nuclei and cytoskeletal components). This was associated with disappearance of HSP25 staining from the brush border of proximal convoluted tubule (PCT) cells. Because no nuclear staining of cortical tubule cells was apparent either in control or ischemic kidneys, ischemia seems to cause a closer association of HSP25 with cytoskeletal components. HSP25 probably participates in the postischemic restructuring of the cytoskeleton of PCT cells

Comb-calibrated solar spectroscopy through a multiplexed single-mode fiber channel

We investigate a new scheme for astronomical spectrograph calibration using the laser frequency comb at the Solar Vacuum Tower Telescope on Tenerife. Our concept is based upon a single-mode fiber channel, that simultaneously feeds the spectrograph with comb light and sunlight. This yields nearly perfect spatial mode matching between the two sources. In combination with the absolute calibration provided by the frequency comb, this method enables extremely robust and accurate spectroscopic measurements. The performance of this scheme is compared to a sequence of alternating comb and sunlight, and to absorption lines from Earth's atmosphere. We also show how the method can be used for radial-velocity detection by measuring the well-explored 5-minute oscillations averaged over the full solar disk. Our method is currently restricted to solar spectroscopy, but with further evolving fiber-injection techniques it could become an option even for faint astronomical targets.Comment: 21 pages, 11 figures. A video abstract for this paper is available on youtube. For watching the video, please follow https://www.youtube.com/watch?v=oshdZgrt89I . The video abstract is also available for streaming and download on the related article website of New Journal of Physic

A Laser Frequency Comb System for Absolute Calibration of the VTT Echelle Spectrograph

A wavelength calibration system based on a laser frequency comb (LFC) was developed in a co-operation between the Kiepenheuer-Institut f\"ur Sonnenphysik, Freiburg, Germany and the Max-Planck-Institut f\"ur Quantenoptik, Garching, Germany for permanent installation at the German Vacuum Tower Telescope (VTT) on Tenerife, Canary Islands. The system was installed successfully in October 2011. By simultaneously recording the spectra from the Sun and the LFC, for each exposure a calibration curve can be derived from the known frequencies of the comb modes that is suitable for absolute calibration at the meters per second level. We briefly summarize some topics in solar physics that benefit from absolute spectroscopy and point out the advantages of LFC compared to traditional calibration techniques. We also sketch the basic setup of the VTT calibration system and its integration with the existing echelle spectrograph.Comment: 9 pages, 2 figures; Solar Physics 277 (2012

Laser frequency combs for astronomical observations

A direct measurement of the universe's expansion history could be made by observing in real time the evolution of the cosmological redshift of distant objects. However, this would require measurements of Doppler velocity drifts of about 1 centimeter per second per year, and astronomical spectrographs have not yet been calibrated to this tolerance. We demonstrate the first use of a laser frequency comb for wavelength calibration of an astronomical telescope. Even with a simple analysis, absolute calibration is achieved with an equivalent Doppler precision of approximately 9 meters per second at about 1.5 micrometers - beyond state-of-the-art accuracy. We show that tracking complex, time-varying systematic effects in the spectrograph and detector system is a particular advantage of laser frequency comb calibration. This technique promises an effective means for modeling and removal of such systematic effects to the accuracy required by future experiments to see direct evidence of the universe's putative acceleration.Comment: Science, 5th September 2008. 18 pages, 7 figures (7 JPG files), including Supporting Online Material. Version with higher resolution figures available at http://astronomy.swin.edu.au/~mmurphy/pub.htm

CFTR mRNA and its truncated splice variant (TRN-CFTR) are differentially expressed during collecting duct ontogeny

AbstractThe collecting duct epithelium originates from the embryonic ureter by branching morphogenesis. Ontogeny-dependent changes of CFTR mRNA expression were assessed by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) in primary monolayer cultures of rat ureteric buds (UB) and cortical collecting ducts, microdissected at different embryonic and postnatal developmental stages. The amount of wild-type CFTR-specific PCR product in UB declined to 20% of the initial value between embryonic gestational day E15 and postnatal day P1. After birth the CFTR product increased transiently between P1 and P7 by a factor of 10 and decreased towards day P14. PCR products specific for TRN-CFTR, a truncated splice variant, however, were low in early embryonic cells, increased markedly between day E17 and P2, and reached a plateau postnatally. Therefore, mRNA encoding TRN-CFTR does not appear to have a specific embryonic-morphogenetic function. By contrast, such function is suggested for wild-type CFTR mRNA as its abundance was high in early embryonic nephrogenesis, as well as during a postnatal period shortly before branching morphogenesis is completed

The Chromospheric Telescope

We introduce the Chromospheric Telescope (ChroTel) at the Observatorio del Teide in Izana on Tenerife as a new multi-wavelength imaging telescope for full-disk synoptic observations of the solar chromosphere. We describe the design of the instrument and summarize its performance during the first one and a half years of operation. We present a method to derive line-of-sight velocity maps of the full solar disk from filtergrams taken in and near the He I infrared line at 10830 \AA.Comment: 12 pages, 9 figure

Enzyme-functionalized biomimetic apatites: concept and perspectives in view of innovative medical approaches

Biomimetic nanocrystalline calcium-deficient apatite compounds are particularly attractive for the setup of bioactive bone-repair scaffolds due to their high similarity to bone mineral in terms of chemical composition, structural and substructural features. As such, along with the increasingly appealing development of moderate temperature engineered routes for sample processing, they have widened the armamentarium of orthopedic and maxillofacial surgeons in the field of bone tissue engineering. This was made possible by exploiting the exceptional surface reactivity of biomimetic apatite nanocrystals, capable of easily exchanging ions or adsorbing (bio)molecules, thus leading to highly-versatile drug delivery systems. In this contribution we focus on the preparation of hybrid materials combining biomimetic nanocrystalline apatites and enzymes (lysozyme and subtilisin). This paper reports physico-chemical data as well as cytotoxicity evaluations towards Cal-72 osteoblast-like cells and finally antimicrobial assessments towards selected strains of interest in bone surgery. Biomimetic apatite/enzyme hybrids could be prepared in varying buffers. They were found to be non-cytotoxic toward osteoblastic cells and the enzymes retained their biological activity (e.g. bond cleavage or antibacterial properties) despite the immobilization and drying processes. Release properties were also examined. Beyond these illustrative examples, the concept of biomimetic apatites functionalized with enzymes is thus shown to be useable in practice, e.g. for antimicrobial purposes, thus widening possible therapeutic perspectives

Two-dimensional solar spectropolarimetry with the KIS/IAA Visible Imaging Polarimeter

Spectropolarimetry at high spatial and spectral resolution is a basic tool to characterize the magnetic properties of the solar atmosphere. We introduce the KIS/IAA Visible Imaging Polarimeter (VIP), a new post-focus instrument that upgrades the TESOS spectrometer at the German VTT into a full vector polarimeter. VIP is a collaboration between the KIS and the IAA. We describe the optical setup of VIP, the data acquisition procedure, and the calibration of the spectropolarimetric measurements. We show examples of data taken between 2005 and 2008 to illustrate the potential of the instrument. VIP is capable of measuring the four Stokes profiles of spectral lines in the range from 420 to 700 nm with a spatial resolution better than 0.5". Lines can be sampled at 40 wavelength positions in 60 s, achieving a noise level of about 2 x 10E-3 with exposure times of 300 ms and pixel sizes of 0.17" x 0.17" (2 x 2 binning). The polarization modulation is stable over periods of a few days, ensuring high polarimetric accuracy. The excellent spectral resolution of TESOS allows the use of sophisticated data analysis techniques such as Stokes inversions. One of the first scientific results of VIP presented here is that the ribbon-like magnetic structures of the network are associated with a distinct pattern of net circular polarization away from disk center. VIP performs spectropolarimetric measurements of solar magnetic fields at a spatial resolution that is only slightly worse than that of the Hinode spectropolarimeter, while providing a 2D field field of view and the possibility to observe up to four spectral regions sequentially with high cadence. VIP can be used as a stand-alone instrument or in combination with other spectropolarimeters and imaging systems of the VTT for extended wavelength coverage.Comment: 10 pages, 8 figures, accepted by Astronomy and Astrophysics v2: figures updated with improved qualit