Witness: The Modern Writer as Witness

Editor\u27s Note [Excerpt] The United States, as a society, is on the brink of profound and positive change. Demographically and culturally, things are improving, and the reason is obvious to people who study history: Conflict pushes us to be better, to strive for principled goals. Consider the inspired eco-advocacy of Greta Thunberg. Or the swearing in of most diverse class of lawmakers in history into the 116th Congress. Or billionaire Robert F. Smith’s pledge to pay off every Morehouse College (in Atlanta, Georgia) student’s debt. Indeed, there are many good people helping and great moments happening in spite of a bleak 24-hour news cycle designed to ruin happiness and to limit our understanding of our human potential. We at Witness see this yearning for transformation in the works we selected. The doorway must be crossed, and the voices and characters we featured in our Winter 2019 issue stand at the vestibule, ready for the light to warm them, primed to fight for that necessary illumination.https://digitalscholarship.unlv.edu/witness/1000/thumbnail.jp

High-resolution Photo-mosaicing of the Rosebud Hydrothermal Vent Site and Surrounding Lava Flows, Galapagos Rift 86W: Techniques and Interpretation

The Rosebud hydrothermal vent field was discovered in May 2002 in the Galapagos Rift near 86W during a series of Alvin dives and ABE autonomous vehicle surveys. Vertical-incidence digital imaging using a 3.1 Mpixel digital camera and strobe illumination from altitudes of 3-5m was carried out during the Alvin dives. A complete survey of the Rosebud vent site was carried out on Alvin Dive 3790. Submersible position was determined by post-cruise integration of 1.2 MHz bottom-lock Doppler sonar velocity data logged at 5Hz, integrated with heading and attitude data from a north-seeking fiber-optic gyroscope logged at 10Hz, and initialized with a surveyed-in long-baseline transponder navigation system providing geodetic position fixes at 15s intervals. The photo-mosaicing process consisted of three main stages: pre-processing, pair-wise image co-registration, and global alignment. Excellent image quality allowed us to avoid lens distortion correction, so images only underwent histogram equalization. Pair-wise co-registration of sequential frames was done partially automatically (where overlap exceeded 70 percent we employed a frequency-domain based technique), and partially manually (when overlap did not exceed 15 percent and manual feature extraction was the only way to find transformations relating the frames). Partial mosaics allowed us to determine which non-sequential frames had substantial overlap, and the corresponding transformations were found via feature extraction. Global alignment of the images consisted of construction of a sparse, nonlinear over-constrained system of equations reflecting positions of the frames in real-world coordinates. This system was solved using least squares, and the solution provided globally optimal positions of the frames in the overall mosaic. Over 700 images were mosaiced resulting in resolution of ~3 mm per pixel. The mosaiced area covers approximately 50 m x 60 m and clearly shows several biological zonations and distribution of lava flow morphologies, including what is interpreted as the contact between older lobate lava and the young sheet flow that hosts Rosebud vent communities. Recruitment of tubeworms, mussels, and clams is actively occurring at more than five locations oriented on a NE-SW trend where vent emissions occur through small cracks in the sheet flow. Large-scale views of seafloor hydrothermal vent sites, such as the one produced for Rosebud, are critical to properly understanding spatial relationships between hydrothermal biological communities, sites of focused and diffuse fluid flow, and the complex array of volcanic and tectonic features at mid-ocean ridge crests. These high-resolution perspectives are also critical to time-series studies where quantitative documentation of changes can be related to variations in hydrothermal, magmatic and tectonic processes

Position paper on high performance computing needs in earth system prediction

The article of record as published may be found at http://dx.doi.org/10.7289/V5862DH3The United States experiences some of the most severe weather on Earth. Extreme weather or climate events - such as hurricanes, tornadoes, flooding, drought, and heat waves - can devastate communities and businesses, cause loss of life and property, and impact valuable infrastructure and natural resources. The number and severity of extreme weather and climate events in the U.S. has risen since 1980, and is projected to continue rising this century. Growing populations in vulnerable areas create increased risks. If current trends continue, damages from extreme weather and climate events could grow four-fold by 2050. Predictions and projections of weather and extreme events across time scales from weather to climate rely on sophisticated numerical models running on High Performance Computing (HPC) systems, which press the frontier of the Nation’s HPC capability. The Nation’s Earth system modeling community has a unique set of HPC requirements which differ from industry needs. Typically, HPC advances are measured using computational peak performance metrics that are ill-suited to Earth system modeling applications. We advocate for a shift in processor design to increase emphasis on memory bandwidth, so Earth system models run more efficiently and better serve the public need

Emergence of CXCR4-Using Human Immunodeficiency Virus Type 1 (HIV-1) Variants in a Minority of HIV-1-Infected Patients following Treatment with the CCR5 Antagonist Maraviroc Is from a Pretreatment CXCR4-Using Virus Reservoir

Antagonists of the human immunodeficiency virus type 1 (HIV-1) coreceptor, CCR5, are being developed as the first anti-HIV agents acting on a host cell target. We monitored the coreceptor tropism of circulating virus, screened at baseline for coreceptor tropism, in 64 HIV-1-infected patients who received maraviroc (MVC, UK-427,857) as monotherapy for 10 days. Sixty-two patients harbored CCR5-tropic virus at baseline and had a posttreatment phenotype result. Circulating virus remained CCR5 tropic in 60/62 patients, 51 of whom experienced an HIV RNA reduction from baseline of >1 log(10) copies/ml, indicating that CXCR4-using variants were not rapidly selected despite CCR5-specific drug pressure. In two patients, viral load declined during treatment and CXCR4-using virus was detected at day 11. No pretreatment factor predicted the emergence of CXCR4-tropic virus during maraviroc therapy in these two patients. Phylogenetic analysis of envelope (Env) clones from pre- and posttreatment time points indicated that the CXCR4-using variants probably emerged by outgrowth of a pretreatment CXCR4-using reservoir, rather than via coreceptor switch of a CCR5-tropic clone under selection pressure from maraviroc. Phylogenetic analysis was also performed on Env clones from a third patient harboring CXCR4-using virus prior to treatment. This patient was enrolled due to a sample labeling error. Although this patient experienced no overall reduction in viral load in response to treatment, the CCR5-tropic components of the circulating virus did appear to be suppressed while receiving maraviroc as monotherapy. Importantly, in all three patients, circulating virus reverted to predominantly CCR5 tropic following cessation of maraviroc