4,118 research outputs found
All Coronal Loops are the Same: Evidence to the Contrary
The 1998 April 20 spectral line data from the Coronal Diagnostics
Spectrometer (CDS) on the {\it Solar and Heliospheric Observatory} (\SOHO)
shows a coronal loop on the solar limb. Our original analysis of these data
showed that the plasma was multi-thermal, both along the length of the loop and
along the line of sight. However, more recent results by other authors indicate
that background subtraction might change these conclusions, so we consider the
effect of background subtraction on our analysis. We show Emission Measure (EM)
Loci plots of three representative pixels: loop apex, upper leg, and lower leg.
Comparisons of the original and background-subtracted intensities show that the
EM Loci are more tightly clustered after background subtraction, but that the
plasma is still not well represented by an isothermal model. Our results taken
together with those of other authors indicate that a variety of temperature
structures may be present within loops.Comment: Accepted for publication in ApJ Letter
Temperature and Emission-Measure Profiles Along Long-Lived Solar Coronal Loops Observed with TRACE
We report an initial study of temperature and emission measure distributions
along four steady loops observed with the Transition Region and Coronal
Explorer (TRACE) at the limb of the Sun. The temperature diagnostic is the
filter ratio of the extreme-ultraviolet 171-angstrom and 195-angstrom
passbands. The emission measure diagnostic is the count rate in the
171-angstrom passband. We find essentially no temperature variation along the
loops. We compare the observed loop structure with theoretical isothermal and
nonisothermal static loop structure.Comment: 10 pages, 3 postscript figures (LaTeX, uses aaspp4.sty). Accepted by
ApJ Letter
Center-to-Limb Variation of the Polarization of Mg II H & K Lines as Measured by CLASP2
Who cares? Magnetograms in the upper chromosphere are needed for accurate magnetic coronal extrapolations. The CLASP2 sounding rocket took spatially resolved spectropolarimetric data of Mg II h & k in the upper chromosphere, that can be used as a pathfinder to routine magnetograms. This work: Preliminary results of the center-to-limb variation (CLV) of the linear polarization in the quiet sun. We compare the signals to recent theoretical calculations of the expected polarization which include PRD, J-state interference, and magneto-optical effects
Superior Capsule Reconstruction: Review of a Novel Operative Technique for Management of Irreparable Rotator Cuff Tears
Rotator cuff tear is a common yet functionally debilitating shoulder condition. Risk factors for failure of repair or inability to repair include advancing age of the patient, chronicity of the tear, and larger tear size. Current operative management options for tears that are considered irreparable include debridement, partial repair, biceps tenotomy, interpositional grafting, tendon transfers, and reverse shoulder arthroplasty. Recently, superior capsular reconstruction has been introduced as an alternative surgical option for these tears and has demonstrated favorable short-term outcomes. However, the literature lacks studies with large numbers of patients, consistency of results, and long-term outcomes. This article reviews the anatomy and function of the rotator cuff and shoulder capsule; patho-etiology of rotator cuff tears, particularly the irreparable ones; and rationale, techniques, outcomes, and future direction of superior capsular reconstruction in the context of this clinical indication
Coronal Temperature Diagnostic Capability of the Hinode/X-Ray Telescope Based on Self-Consistent Calibration
The X-Ray Telescope (XRT) onboard the Hinode satellite is an X-ray imager
that observes the solar corona with unprecedentedly high angular resolution
(consistent with its 1" pixel size). XRT has nine X-ray analysis filters with
different temperature responses. One of the most significant scientific
features of this telescope is its capability of diagnosing coronal temperatures
from less than 1 MK to more than 10 MK, which has never been accomplished
before. To make full use of this capability, accurate calibration of the
coronal temperature response of XRT is indispensable and is presented in this
article. The effect of on-orbit contamination is also taken into account in the
calibration. On the basis of our calibration results, we review the
coronal-temperature-diagnostic capability of XRT
Urban Health Indicators and Indices- Current Status,
Though numbers alone may be insufficient to capture the nuances of population health, they provide a common language of appraisal and furnish clear evidence of disparities and inequalities. Over the past 30 years, facilitated by high speed computing and electronics, considerable investment has been made in the collection and analysis of urban health indicators, environmental indicators, and methods for their amalgamation. Much of this work has been characterized by a perceived need for a standard set of indicators. We used publication databases (e.g. Medline) and web searches to identify compilations of health indicators and health metrics. We found 14 long-term large-area compilations of health indicators and determinants and seven compilations of environmental health indicators, comprising hundreds of metrics. Despite the plethora of indicators, these compilations have striking similarities in the domains from which the indicators are drawn—an unappreciated concordance among the major collections. Research with these databases and other sources has produced a small number of composite indices, and a number of methods for the amalgamation of indicators and the demonstration of disparities. These indices have been primarily used for large-area (nation, region, state) comparisons, with both developing and developed countries, often for purposes of ranking. Small area indices have been less explored, in part perhaps because of the vagaries of data availability, and because idiosyncratic local conditions require flexible approaches as opposed to a fixed format. One result has been advances in the ability to compare large areas, but with a concomitant deficiency in tools for public health workers to assess the status of local health and health disparities. Large area assessments are important, but the need for small area action requires a greater focus on local information and analysis, emphasizing method over prespecified content
Hinode Calibration for Precise Image Co-alignment between SOT and XRT (November 2006 -- April 2007)
To understand the physical mechanisms for activity and heating in the solar
atmosphere, the magnetic coupling from the photosphere to the corona is an
important piece of information from the Hinode observations, and therefore
precise positional alignment is required among the data acquired by different
telescopes. The Hinode spacecraft and its onboard telescopes were developed to
allow us to investigate magnetic coupling with co-alignment accuracy better
than 1 arcsec. Using the Mercury transit observed on 8 November 2006 and
co-alignment measurements regularly performed on a weekly basis, we have
determined the information necessary for precise image co-alignment and have
confirmed that co-alignment better than 1 arcsec can be realized between Solar
Optical Telescope (SOT) and X-Ray Telescope (XRT) with our baseline
co-alignment method. This paper presents results from the calibration for
precise co-alignment of CCD images from SOT and XRT.Comment: 8 pages, 9 figures, accepted for publication in PASJ (Hinode Special
issue
Optical Alignment of the High-Precision UV Spectro-Polarimeter (CLASP2)
Chromospheric LAyer Spectro-Polarimeter (CLASP2) is our next sounding rocket experiment after the success of Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP1). CLASP2 is scheduled to launch in 2019, and aims to achieve high precision measurements of the linear and circular polarizations in the Mg II h & k lines near the 280 nm, whose line cores originate in the upper solar chromosphere. The CLASP2 spectro-polarimeter follows very successful design concept of the CLASP1 instrument with the minimal modification. A new grating was fabricated with the same radius of curvature as the CLASP1 grating, but with a different ruling density. This allows us to essentially reuse the CLASP1 mechanical structures and layout of the optics. However, because the observing wavelength of CLASP2 is twice longer than that of CLASP1, a magnifier optical system was newly added in front of the cameras to double the focal length of CLASP2 in order to maintain the same wavelength resolution as CLASP1 (0.01 nm). Meanwhile, a careful optical alignment of the specto-polarimeter is required to reach the 0.01 nm wavelength resolution. Therefore, we established an efficient alignment procedure for the CLASP2 spectro-polarimeter based on an experience of CLASP1. Here, we explain in detail the methods for achieving the optical alignment of the CLASP2 spectro-polarimeter and discuss our results by comparing with the performance requirements
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