On the formation of fluvial islands

This research analyzes the effects of islands on river process and the effects river processes have on island formation. A fluvial island is defined herein as a land mass within a river channel that is separated from the floodplain by water on all sides, exhibits some stability, and remains exposed during bankfull flow. Fluvial islands are present in nearly all major rivers. They must therefore have some impact on the fluid mechanics of the system, and yet there has never been a detailed study on fluvial islands. Islands represent a more natural state of a river system and have been shown to provide hydrologic variability and biotic diversity for the river. This research describes the formation of fluvial islands, investigates the formation of fluvial islands experimentally, determines the main relations between fluvial islands and river processes, compares and describes relationships between fluvial islands and residual islands found in megaflood outwash plains, and reaches conclusions regarding island shape evolution and flow energy loss optimization. Fluvial islands are known to form by at least nine separate processes: avulsion, gradual degradation of channel branches, lateral shifts in channel position, stabilization of a bar or riffle, isolation of structural features, rapid incision of flood deposits, sediment deposition in the lee of an obstacle, isolation of material deposited by mass movement, and isolation of riparian topography after the installation of a dam. A classification scheme is proposed in order to describe the islands and relate them to the river processes. Several physical experiments were performed to analyze both the processes involved with island formation and the effects islands have on river processes. The experiments performed herein ranged in scale from a 0.45-meter wide flume to the 100-meter wide Willamette River. The analyses describe the effects of islands on flow processes, such as drag force, energy loss, and flow patterns. Previous research has shown that the drag force on a streamlined object in a water flow can be minimized by setting the object's aspect ratio to about three. This research analyzed the flow patterns behind a blunt object in a streamfiow and showed that conditions can be conducive to creating a streamlined, depositional shape with an aspect ratio (length/width) of about three. By introducing islands of various aspect ratios into a streamflow and measuring the flow characteristics, it is shown that the energy loss is minimized with the island's aspect ratio around three. Aerial photographs of fluvial islands were analyzed for thirteen American rivers and a watershed-independent correlation was found for the shape parameters. The average length/width ratio of all analyzed fluvial islands was 4.14. By describing the island shapes with a lemniscate form, the islands were compared with dimensionless properties. The use of dimensionless properties allowed for the analyses of terrestrial fluvial islands to be compared to analyses of fluvially-formed residual islands in unique megaflood areas, such as the Channeled Scablands and Mars Channels. The shape characteristics of the islands were found to be similar, therefore similar relationships between the islands and flow processes are assumed

Can It Work for Us Too? Results from Using West Point’s Fundamentals of Engineering Mechanics and Design Course Redesign

At the 2017 ASEE National Conference and Exhibition two papers from the US Military Academy (one in the Mechanics Division and one in the Civil Engineering Division) detailed a redesign of their initial mechanics sequence and the introduction of Inquiry Based Learning Activities. The authors of those papers extended an offer to share details and materials of their course redesign and associated lesson activities. The authors of this paper took them up on that offer and in the Fall of 2017 implemented the changes proposed at the US Military Academy at their institution. The question this paper strives to answer is, can a similar course redesign produce similar results at an institution, that in many respects is very different from the US Military Academy; essentially is the West Point redesign reproducible and the results replicable and if so under what conditions? This paper will strive to use many of the same measures from the original paper in the analysis of the success or failure of the implementation. The paper will also examine and document the differences between the students and institutions. It will then note differences in the administration of the course, changes made, and conduct of the course, to include number of instructors, sections, section size, group size and the demographic make-up of students in the course and list the effect of the differences discovered at this time. Finally, considering differences and similarities, the paper will analyze and capture the results and the effects of the two applications of the course redesign to come up with an answer to the research question

The Origin Recognition Complex Interacts with a Subset of Metabolic Genes Tightly Linked to Origins of Replication

The origin recognition complex (ORC) marks chromosomal sites as replication origins and is essential for replication initiation. In yeast, ORC also binds to DNA elements called silencers, where its primary function is to recruit silent information regulator (SIR) proteins to establish transcriptional silencing. Indeed, silencers function poorly as chromosomal origins. Several genetic, molecular, and biochemical studies of HMR-E have led to a model proposing that when ORC becomes limiting in the cell (such as in the orc2-1 mutant) only sites that bind ORC tightly (such as HMR-E) remain fully occupied by ORC, while lower affinity sites, including many origins, lose ORC occupancy. Since HMR-E possessed a unique non-replication function, we reasoned that other tight sites might reveal novel functions for ORC on chromosomes. Therefore, we comprehensively determined ORC “affinity” genome-wide by performing an ORC ChIP–on–chip in ORC2 and orc2-1 strains. Here we describe a novel group of orc2-1–resistant ORC–interacting chromosomal sites (ORF–ORC sites) that did not function as replication origins or silencers. Instead, ORF–ORC sites were comprised of protein-coding regions of highly transcribed metabolic genes. In contrast to the ORC–silencer paradigm, transcriptional activation promoted ORC association with these genes. Remarkably, ORF–ORC genes were enriched in proximity to origins of replication and, in several instances, were transcriptionally regulated by these origins. Taken together, these results suggest a surprising connection among ORC, replication origins, and cellular metabolism

Science overview of the Europa Clipper mission

The goal of NASA’s Europa Clipper mission is to assess the habitability of Jupiter’s moon Europa. After entering Jupiter orbit in 2030, the flight system will collect science data while flying past Europa 49 times at typical closest approach distances of 25–100 km. The mission’s objectives are to investigate Europa’s interior (ice shell and ocean), composition, and geology; the mission will also search for and characterize any current activity including possible plumes. The science objectives will be accomplished with a payload consisting of remote sensing and in-situ instruments. Remote sensing investigations cover the ultraviolet, visible, near infrared, and thermal infrared wavelength ranges of the electromagnetic spectrum, as well as an ice-penetrating radar. In-situ investigations measure the magnetic field, dust grains, neutral gas, and plasma surrounding Europa. Gravity science will be achieved using the telecommunication system, and a radiation monitoring engineering subsystem will provide complementary science data. The flight system is designed to enable all science instruments to operate and gather data simultaneously. Mission planning and operations are guided by scientific requirements and observation strategies, while appropriate updates to the plan will be made tactically as the instruments and Europa are characterized and discoveries emerge. Following collection and validation, all science data will be archived in NASA’s Planetary Data System. Communication, data sharing, and publication policies promote visibility, collaboration, and mutual interdependence across the full Europa Clipper science team, to best achieve the interdisciplinary science necessary to understand Europa