We present an overview of the National Science Foundation’s Daniel K. Inouye Solar Telescope (DKIST), its instruments, and support facilities. The 4 m aperture DKIST provides the highest-resolution observations of the Sun ever achieved. The large aperture of DKIST combined with state-of-the-art instrumentation provide the sensitivity to measure the vector magnetic field in the chromosphere and in the faint corona, i.e. for the first time with DKIST we will be able to measure and study the most important free-energy source in the outer solar atmosphere – the coronal magnetic field. Over its operational lifetime DKIST will advance our knowledge of fundamental astronomical processes, including highly dynamic solar eruptions that are at the source of space-weather events that impact our technological society. Design and construction of DKIST took over two decades. DKIST implements a fast (f/2), off-axis Gregorian optical design. The maximum available field-of-view is 5 arcmin. A complex thermal-control system was implemented in order to remove at prime focus the majority of the 13 kW collected by the primary mirror and to keep optical surfaces and structures at ambient temperature, thus avoiding self-induced local seeing. A high-order adaptive-optics system with 1600 actuators corrects atmospheric seeing enabling diffraction limited imaging and spectroscopy. Five instruments, four of which are polarimeters, provide powerful diagnostic capability over a broad wavelength range covering the visible, near-infrared, and mid-infrared spectrum. New polarization-calibration strategies were developed to achieve the stringent polarization accuracy requirement of 5×10−4. Instruments can be combined and operated simultaneously in order to obtain a maximum of observational information. Observing time on DKIST is allocated through an open, merit-based proposal process. DKIST will be operated primarily in “service mode” and is expected to on average produce 3 PB of raw data per year. A newly developed data center located at the NSO Headquarters in Boulder will initially serve fully calibrated data to the international users community. Higher-level data products, such as physical parameters obtained from inversions of spectro-polarimetric data will be added as resources allow.
The present study is an important step in understanding the brain case as a structure. Beams taken from the layered regions of embalmed calvaria were repeatedly tested in threepoint bending at various span lengths to determine the resistance of layered cranial bone to bending and shearing deflection. These beams were also strain gaged and loaded to failure in fourpoint bending to study the failure response of layered cranial bone. The layered beam theory used in this study was found to provide a valid relationship between the constituent material properties and structural geometry of layered cranial bone and its flexural response.
Beam samples containing cranial sutures were prepared from embalmed and unembalmed cranial bone and were tested to determine their flexural stiffness and strength. With the aid of layered beam theory, the flexural stiffnesses of beams containing cranial sutures were compared to hypothetical layered cranial bone beams which did not contain sutures. The bending stiffnesses and strengths of cranial sutures were found to be generally the same as comparable layered cranial bone structures. Embalmed samples were slightly stiffer and stronger in bending than unembalmed samples.
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