Modeling oxygen dynamics and predicting hypoxic conditions in the Neuse River Estuary, North Carolina

Dissolved oxygen (DO) is essential for marine organisms to maintain basic metabolic processes. Conditions of low DO concentrations, hypoxia, can stress and kill organisms. Hypoxia often occurs in bottom water in estuaries as a result of increased DO consumption and water column density stratification. Previous DO modeling studies have taken into account physical and biogeochemical processes in forecasting hypoxic events. However, these studies have typically focused on variations over timescales of weeks to months. In many estuaries, oxygen levels can vary over much shorter timescales due to changes in mixing associated with tides or wind. We analyzed temperature, salinity, and DO profiles measured every 30 minutes in the Neuse River Estuary (NRE) of North Carolina from June to July of 2016 to understand the factors that drive hypoxia in a shallow, intermittently mixed estuary. Bottom DO varied between well-oxygenated and hypoxic over hours to days. Bottom DO concentration correlated strongly with salinity differences between the top and bottom water. We assessed the ability of a two-layer box model, developed to predict seasonal variations in DO in the same system, to predict DO variations on the order of hours to days. The model was unable to capture the DO variations in both the top and bottom water layers that were observed as the water column mixed and as it stratified. Sensitivity analyses suggested that changes in bottom DO as the water column stratified were not well represented by a consumption term with a constant rate coefficient, and the parameter values for the term that describes vertical mixing are not reasonable for this system over these timescales. This simple model could be improved and used to forecast hypoxic events in the NRE, which could help inform nutrient management policies and the management of fisheries and recreation within the estuary and other similar ecosystems.Bachelor of Scienc

Ministerens ordbog. Matthias Moths store danske ordbog 1700-1717

Det er ikke hver dag en 300 år gammel bog bliver dagens hovedhistorie i medierne, men det var hvad der skete da Moths Ordbog gik i luften online i oktober. Ordbogen er da også helt usædvanlig ved ikke – som det ellers dengang var sædvane – kun at indeholde det almindeligt accepterede tale- og skriftsprog, men også det folkelige og “vulgære”.Moths Ordbog giver os dermed et sjældent indblik i 1700-tallets slang og hverdagssprog. Den kan findes på adressen <mothsordbog.dk>. Det er ikke hver dag en 300 år gammel bog bliver dagens hovedhistorie i medierne, men det var hvad der skete da Moths Ordbog gik i luften online i oktober. Ordbogen er da også helt usædvanlig ved ikke – som det ellers dengang var sædvane – kun at indeholde det almindeligt accepterede tale- og skriftsprog, men også det folkelige og “vulgære”.Moths Ordbog giver os dermed et sjældent indblik i 1700-tallets slang og hverdagssprog. Den kan findes på adressen <mothsordbog.dk>.&nbsp

Holbergordbogen – en nordisk forfatterskabsordbog

Holberg-Ordbog (Copenhagen, Oslo 1981–88) covers the complete works of LudvigHolberg, an outstanding Dano-Norwegian author in the first half of the 18th century,versatile as a dramatic (comedy), historical, and essayistic writer. This paper presentsthe five volume lexicographic work, its scope and function as an author’s dictionary ofthe so-called selective thesaurus type. By its editorial practice the Holberg dictionary isa descendant of the Danish national dictionary, Ordbog over det danske Sprog (1919–56), in return the specialist dictionary can – on many points – furnish important supplementarymaterial for Danish lexicography in general, as is shown by some examples. Afinal section discusses briefly some other Scandinavian and European author’s dictionariesand concordances/indexes, and the author sides with Wiegand (1986) and Mattausch(1990) in their underlining of the importance of semantic author’s dictionariesversus concordances and indexes

Measuring the In-Process Figure, Final Prescription, and System Alignment of Large Optics and Segmented Mirrors Using Lidar Metrology

The fabrication of large optics is traditionally a slow process, and fabrication capability is often limited by measurement capability. W hile techniques exist to measure mirror figure with nanometer precis ion, measurements of large-mirror prescription are typically limited to submillimeter accuracy. Using a lidar instrument enables one to measure the optical surface rough figure and prescription in virtuall y all phases of fabrication without moving the mirror from its polis hing setup. This technology improves the uncertainty of mirror presc ription measurement to the micron-regime

LIDAR Metrology for Prescription Characterization and Alignment of Large Mirrors

We describe the use of LIDAR, or "laser radar," (LR) as a fast, accurate, and non-contact tool for the measurement of the radius of curvature (RoC) of large mirrors. We report the results of a demonstration of this concept using a commercial laser radar system. We measured the RoC of a 1.4m x 1m spherical mirror with a nominal RoC of 4.6 m with a manufacturing tolerance of 4600mm +/- 6mm. The prescription of the mirror is related to its role as ground support equipment used in the test of part of the James Webb Space Telescope (JWST). The RoC of such a large mirror is not easily measured without contacting the surface. From a position near the center of curvature of the mirror, the LIDAR scanned the mirror surface, sampling it with 1 point per 3.5 sq cm. The measurement consisted of 3983 points and lasted only a few minutes. The laser radar uses the LIDAR signal to provide range, and encoder information from angular azimuth and elevation rotation stages provide the spherical coordinates of a given point. A best-fit to a sphere of the measured points was performed. The resulting RoC was within 20 ppm of the nominal RoC, also showing good agreement with the results of a laser tracker-based, contact metrology. This paper also discusses parameters such as test alignment, scan density, and optical surface type, as well as future possible application for full prescription characterization of aspherical mirrors, including radius, conic, off-axis distance, and aperture

Laser Radar Through the Window (LRTW) Coordinate Correction Method

A method for corrections of measurements of points of interests measured by beams of radiation propagating through stratified media including performance of ray-tracing of at least one ray lunched from a metrology instrument in a direction of an apparent point of interest, calculation a path length of the ray through stratified medium, and determination of coordinates of true position of the point interest using the at least one path length and the direction of propagation of the ray

Cryogenic Thermal Vacuum Testing with Remote Optical Metrology

Flexure Engineering was awarded an SBIR to research and develop technology needed to build a thermal vacuum chamber made to take laser radar metrology through a window. The XATF test is proof of concept for this, and demonstrated the need for such a chamber. XATF refers to two pieces of critical ground support equipment for NASA's JWST (James Webb Space Telescope) Integrated Science Instrument Module (ISIM), the ISIM Alignment Target Fixture (IATF) and the Master Alignment Target Fixture (MATF). These optical alignment assemblies require characterization while under cryogenic temperature. A thermal vacuum chamber equipped with a shroud cooled with gaseous and liquid nitrogen was used. An inner shroud was cooled with liquid helium to approximately 30K. The XATF assemblies were kinematically mounted and oriented inside the inner shroud such that the optical targets were visible from outside an optical window on one of the chamber ports. Laser radar and theodolite mounted outside the window took measurements of various optical targets. Two cold cycles were completed. A third cycle was aborted. Metrology was successfully taken. There were some problems with the helium system. The cryo pumps were turned off to reduce vibrations during metrology. Many new technologies and testing methods must be developed for JWST and future programs that will require precision measurements. These technologies will be applicable to other cold temperature applications, such as lunar missions and superconductors. Remote metrology technologies can also be applicable to testing in harsh environments. Facilities with remote metrology capability will be valuable

JWST Near-Infrared Detector Degradation: Finding the Problem, Fixing the Problem, and Moving Forward

The James Webb Space Telescope (JWST) is the successor to the Hubble Space Telescope. JWST will be an infrared optimized telescope, with an approximately 6.5 m diameter primary mirror, that is located at the Sun-Earth L2 Lagrange point. Three of JWST's four science instruments use Teledyne HgCdTe HAWAII-2RG (H2RG) near infrared detector arrays. During 2010, the JWST Project noticed that a few of its 5 micron cutoff H2RG detectors were degrading during room temperature storage, and NASA chartered a "Detector Degradation Failure Review Board" (DD-FRB) to investigate. The DD-FRB determined that the root cause was a design flaw that allowed indium to interdiffuse with the gold contacts and migrate into the HgCdTe detector layer. Fortunately, Teledyne already had an improved design that eliminated this degradation mechanism. During early 2012, the improved H2RG design was qualified for flight and JWST began making additional H2RGs. In this article we present the two public DD-FRB "Executiye Summaries" that: (1) determined the root cause of the detector degradation and (2) defined tests to determine whether the existing detectors are qualified for flight. We supplement these with a brief introduction to H2RG detector arrays, and a discussion of how the JWST Project is using cryogenic storage to retard the degradation rate of the existing flight spare H2RGs