SeaWiFS Technical Report Series

This document provides brief reports, or case studies, on a number of investigations sponsored by the Calibration and Validation Team (CVT) within the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Project. Chapter I describes the calibration and characterization of the GSFC sphere, which was used in the recent recalibration of the SeaWiFS instrument. Chapter 2 presents a revision of the diffuse attenuation coefficient, K(490), algorithm based on the SeaWiFS wavelengths. Chapter 3 provides an implementation scheme for an algorithm to remove out-of-band radiance when using a sensor calibration based on a finite width (truncated) spectral response function, e.g., between the 1% transmission points. Chapter 4 describes the implementation schemes for the stray light quality flag (local area coverage [LAC] and global area coverage [GAC]) and the LAC stray light correction

SeaWiFS Postlaunch Technical Report Series

The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) was originally calibrated by the instrument's manufacturer, Santa Barbara Research Center (SBRC), in November 1993. In preparation for an August 1997 launch, the SeaWiFS Project and the National Institute of Standards and Technology (NIST) undertook a second calibration of SeaWiFS in January and April 1997 at the facility of the spacecraft integrator, Orbital Sciences Corporation (OSC). This calibration occurred in two phases, the first after the final thermal vacuum test, and the second after the final vibration test of the spacecraft. For the calibration, SeaWiFS observed an integrating sphere from the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) at four radiance levels. The spectral radiance of the sphere at these radiance levels was also measured by the SeaWiFS Transfer Radiometer (SXR). In addition, during the calibration, SeaWiFS and the SXR observed the sphere at 16 radiance levels to determine the linearity of the SeaWiFS response. As part of the calibration analysis, the GSFC sphere was also characterized using a GSFC spectroradiometer. The 1997 calibration agrees with the initial 1993 calibration to within +/- 4%. The new calibration coefficients, computed before and after the vibration test, agree to within 0.5%. The response of the SeaWiFS channels in each band is linear to better than 1%. In order to compare to previous and current methods, the SeaWiFS radiometric responses are presented in two ways: using the nominal center wave-lengths for the eight bands; and using band-averaged spectral radiances. The band-averaged values are used in the flight calibration table. An uncertainty analysis for the calibration coefficients is also presented

Sea WiFS Technical Report Series: The fourth SeaWIFS Intercalibration Round-Robin Experiment (SIRREX-4), May 1995

This report documents the fourth Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Intercalibration Round-Robin Experiment (SIRREX-4), which was held at the National Institute of Standards and Technology (NIST) on 3-10 May 1995. The agenda for SIRREX-4 was established by a consensus reached at the conclusion of SIRREX-3: there should be an emphasis on training and work to foster and encourage uniform use of accepted protocols for calibrating radiometric instruments in the laboratory. The goal was to host the activity in a setting where proper techniques could be discussed and demonstrated. It seemed appealing to split the day between morning lectures and afternoon laboratory exercises or practicals. The former gave the user community a chance to present what was important to them and discuss it with acknowledged experts in radiometry, while the latter presented a unique opportunity for training and evaluation in the presence of these same experts. The five laboratory sessions were concerned with (1) determining the responsivity of a spectroradiometer and the spectral radiance of an unknown integrating sphere source, (2) demonstrating spectral field calibration procedures for an integrating sphere using three different instruments, (3) measuring spectral radiance using the plaque method, (4) setting up and aligning lamp calibration transfer standards using the NIST specifications for irradiance measurements, and (5) characterizing radiometric instruments. In addition to documenting some supplemental studies performed outside the laboratory sessions, this report includes an evaluation of the hardware that has been used during the SIRREX activities plus a critical evaluation of SIRREX objectives

The role of networks to overcome large-scale challenges in tomography: The non-clinical tomography users research network

Our ability to visualize and quantify the internal structures of objects via computed tomography (CT) has fundamentally transformed science. As tomographic tools have become more broadly accessible, researchers across diverse disciplines have embraced the ability to investigate the 3D structure-function relationships of an enormous array of items. Whether studying organismal biology, animal models for human health, iterative manufacturing techniques, experimental medical devices, engineering structures, geological and planetary samples, prehistoric artifacts, or fossilized organisms, computed tomography has led to extensive methodological and basic sciences advances and is now a core element in science, technology, engineering, and mathematics (STEM) research and outreach toolkits. Tomorrow's scientific progress is built upon today's innovations. In our data-rich world, this requires access not only to publications but also to supporting data. Reliance on proprietary technologies, combined with the varied objectives of diverse research groups, has resulted in a fragmented tomography-imaging landscape, one that is functional at the individual lab level yet lacks the standardization needed to support efficient and equitable exchange and reuse of data. Developing standards and pipelines for the creation of new and future data, which can also be applied to existing datasets is a challenge that becomes increasingly difficult as the amount and diversity of legacy data grows. Global networks of CT users have proved an effective approach to addressing this kind of multifaceted challenge across a range of fields. Here we describe ongoing efforts to address barriers to recently proposed FAIR (Findability, Accessibility, Interoperability, Reuse) and open science principles by assembling interested parties from research and education communities, industry, publishers, and data repositories to approach these issues jointly in a focused, efficient, and practical way. By outlining the benefits of networks, generally, and drawing on examples from efforts by the Non-Clinical Tomography Users Research Network (NoCTURN), specifically, we illustrate how standardization of data and metadata for reuse can foster interdisciplinary collaborations and create new opportunities for future-looking, large-scale data initiatives

Student politics, teaching politics, black politics: an interview with Ansel Wong

Ansel Wong is the quiet man of British black politics, rarely in the limelight and never seeking political office. And yet his ‘career’ here – from Black Power firebrand to managing a multimillion budget as head of the Greater London Council’s Ethnic Minority Unit in the 1980s – spells out some of the most important developments in black educational and cultural projects. In this interview, he discusses his identification with Pan-Africanism, his involvement in student politics, his role in the establishment of youth projects and supplementary schools in the late 1960s and 1970s, and his involvement in black radical politics in London in the same period, all of which took place against the background of revolutionary ferment in the Third World and the world of ideas, and were not without their own internal class and ethnic conflicts

Terminal Deoxynucleotidyl Transferase: The Story of A Misguided DNA Polymerase

Nearly every DNA polymerase characterized to date exclusively catalyzes the incorporation of mononucleotides into a growing primer using a DNA or RNA template as a guide to direct each incorporation event. There is, however, one unique DNA polymerase designated terminal deoxynucleotidyl transferase that performs DNA synthesis using only single-stranded DNA as the nucleic acid substrate. In this chapter, we review the biological role of this enigmatic DNA polymerase and the biochemical mechanism for its ability to perform DNA synthesis in the absence of a templating strand. We compare and contrast the molecular events for template-independent DNA synthesis catalyzed by terminal deoxynucleotidyl transferase with other well-characterized DNA polymerases that perform template-dependent synthesis. This includes a quantitative inspection of how terminal deoxynucleotidyl transferase binds DNA and dNTP substrates, the possible involvement of a conformational change that precedes phosphoryl transfer, and kinetic steps that are associated with the release of products. These enzymatic steps are discussed within the context of the available structures of terminal deoxynucleotidyl transferase in the presence of DNA or nucleotide substrate. In addition, we discuss the ability of proteins involved in replication and recombination to regulate the activity of the terminal deoxynucleotidyl transferase. Finally, the biomedical role of this specialized DNA polymerase is discussed focusing on its involvement in cancer development and its use in biomedical applications such as labeling DNA for detecting apoptosis

Tempo and Pattern of Avian Brain Size Evolution

Relative brain sizes in birds can rival those of primates, but large-scale patterns and drivers of avian brain evolution remain elusive. Here, we explore the evolution of the fundamental brain-body scaling relationship across the origin and evolution of birds. Using a comprehensive dataset sampling> 2,000 modern birds, fossil birds, and theropod dinosaurs, we infer patterns of brain-body co-variation in deep time. Our study confirms that no significant increase in relative brain size accompanied the trend toward miniaturization or evolution of flight during the theropod-bird transition. Critically, however, theropods and basal birds show weaker integration between brain size and body size, allowing for rapid changes in the brain-body relationship that set the stage for dramatic shifts in early crown birds. We infer that major shifts occurred rapidly in the aftermath of the Cretaceous-Paleogene mass extinction within Neoaves, in which multiple clades achieved higher relative brain sizes because of a reduction in body size. Parrots and corvids achieved the largest brains observed in birds via markedly different patterns. Parrots primarily reduced their body size, whereas corvids increased body and brain size simultaneously (with rates of brain size evolution outpacing rates of body size evolution). Collectively, these patterns suggest that an early adaptive radiation in brain size laid the foundation for subsequent selection and stabilization

The role of networks to overcome large-scale challenges in tomography : the non-clinical tomography users research network

Our ability to visualize and quantify the internal structures of objects via computed tomography (CT) has fundamentally transformed science. As tomographic tools have become more broadly accessible, researchers across diverse disciplines have embraced the ability to investigate the 3D structure-function relationships of an enormous array of items. Whether studying organismal biology, animal models for human health, iterative manufacturing techniques, experimental medical devices, engineering structures, geological and planetary samples, prehistoric artifacts, or fossilized organisms, computed tomography has led to extensive methodological and basic sciences advances and is now a core element in science, technology, engineering, and mathematics (STEM) research and outreach toolkits. Tomorrow's scientific progress is built upon today's innovations. In our data-rich world, this requires access not only to publications but also to supporting data. Reliance on proprietary technologies, combined with the varied objectives of diverse research groups, has resulted in a fragmented tomography-imaging landscape, one that is functional at the individual lab level yet lacks the standardization needed to support efficient and equitable exchange and reuse of data. Developing standards and pipelines for the creation of new and future data, which can also be applied to existing datasets is a challenge that becomes increasingly difficult as the amount and diversity of legacy data grows. Global networks of CT users have proved an effective approach to addressing this kind of multifaceted challenge across a range of fields. Here we describe ongoing efforts to address barriers to recently proposed FAIR (Findability, Accessibility, Interoperability, Reuse) and open science principles by assembling interested parties from research and education communities, industry, publishers, and data repositories to approach these issues jointly in a focused, efficient, and practical way. By outlining the benefits of networks, generally, and drawing on examples from efforts by the Non-Clinical Tomography Users Research Network (NoCTURN), specifically, we illustrate how standardization of data and metadata for reuse can foster interdisciplinary collaborations and create new opportunities for future-looking, large-scale data initiatives