Studies of fluid instabilities in flows of lava and debris

At least two instabilities have been identified and utilized in lava flow studies: surface folding and gravity instability. Both lead to the development of regularly spaced structures on the surfaces of lava flows. The geometry of surface folds have been used to estimate the rheology of lava flows on other planets. One investigation's analysis assumed that lava flows have a temperature-dependent Newtonian rheology, and that the lava's viscosity decreased exponentially inward from the upper surface. The author reviews studies by other investigators on the analysis of surface folding, the analysis of Taylor instability in lava flows, and the effect of surface folding on debris flows

The Importance of Self-Selection in Casino Cannibalization of State Lotteries

This note extends the work of Elliott and Navin (2002) on the substitutability of commercial casinos and state lotteries by controlling for a potential negative selection bias. We utilize a Heckman two-step selection correction in which our first stage probit involves whether or not a state has legalized commercial casinos. Results indicate that a $1 increase in state casino tax revenue will reduce net lottery proceeds by$0.56. This estimate is 33% smaller than what has been found in other studies, which is consistent with a negative selection bias.

Factors controlling lava dome morphology

Research suggests that variations in lava dome morphology on different planets will depend much more critically on local gravity and the style of eruption than on the magma composition, ambient temperature, or the relative roles of convective and radiative cooling. Eruption style in turn reflects differences in tectonic conditions and the ability of magma to exsolve volatiles. Observed crude correlations between silica content and calculated yield strengths for terrestrial lava flows and domes probably are do to differences in extrusion rate and volatile solubility, rather than intrinsic rheological properties. Thus, even after taking the known effect of gravity into account, observed differences in gross dome morphology on different planets cannot by themselves be directly related to composition. Additional information such as the distribution of surface textures and structures, or spectroscopic data will be needed to conclusively establish dome compositions

Communication for Teams of Networked Robots

There are a large class of problems, from search and rescue to environmental monitoring, that can benefit from teams of mobile robots in environments where there is no existing infrastructure for inter-agent communication. We seek to address the problems necessary for a team of small, low-power, low-cost robots to deploy in such a way that they can dynamically provide their own multi-hop communication network. To do so, we formulate a situational awareness problem statement that specifies both the physical task and end-to-end communication rates that must be maintained. In pursuit of a solution to this problem, we address topics ranging from the modeling of point-to-point wireless communication to mobility control for connectivity maintenance. Since our focus is on developing solutions to these problems that can be experimentally verified, we also detail the design and implantation of a decentralized testbed for multi-robot research. Experiments on this testbed allow us to determine data-driven models for point-to-point wireless channel prediction, test relative signal-strength-based localization methods, and to verify that our algorithms for mobility control maintain the desired instantaneous rates when routing through the wireless network. The tools we develop are integral to the fielding of teams of robots with robust wireless network capabilities

Geometry of Silicic Dikes Beneath the Inyo Domes, California

Structural geologic evidence in the vicinity of the Inyo Domes indicates that the youngest extrusive products were erupted from a silicic dike that divided into at least three segments which underwent up to 30° of clockwise rotation as they neared the surface. The geometry of ground cracks, explosion craters, and surface structures on the domes suggest that the dike may have propagated laterally from a source beneath Mammoth Mountain, with both the overall-dike and the individual segments rising as they moved northward. Structural evidence and tephrochronology also imply that the actual vents may have migrated northward along individual dike segments as the activity evolved from explosive eruptions to more quiet emplacement of lavas. Monitoring of changing patterns of ground cracks and faults may assist in predicting the sites and timing of future eruptions

Looking backward and forward: volcanology in the years 2000, 2010, 2020, and beyond

Figuring out how volcanoes work is one of the geoscience’s most complex puzzles. Clues of all sizes, shapes, and colors are scattered across every continent, the bottom of the ocean, in the atmosphere, and on the surfaces of other planets. Generations of geologists, geophysicists, geodesists, and geochemists have used field observations, laboratory measurements, and theory to fill gaps left by their predecessors. Yet critical uncertainties remain. Why do eruptions begin? What determines their intensity? What controls their frequency and style of activity? What causes them to end? These unsolved issues leave society increasingly vulnerable to volcanic disruptions. Hundreds of published papers supplemented by dozens of review articles and compendia like the Encyclopedia of VolcanologyFootnote1 each offer a snapshot showing steps volcanologists have taken to piece together answers to these fundamental questions

The Trauma of Trump\u27s Family Separation and Child Detention Actions: A Children\u27s Rights Perspective

In April 2018, the Trump Administration publicly announced a new zero-tolerance policy for illegal entries at the U.S. border. This action kicked off a wave of family separations that made headlines and drew criticism from around the globe. Despite resounding condemnation of these actions, the Trump Administration defended its family separation policy as a “tough deterrent.” At least 2,600 families were torn apart in the ensuing months. And subsequent reports—from both the government and others—have detailed widespread abuses of and substandard conditions for children held in detention centers. The consequences of these separations and the maltreatment of children in detention are pronounced. The trauma that children have endured potentially has lifelong ramifications. This Article provides an indepth, children’s rights-based analysis of the Trump Administration’s family separation and child detention policies and actions. A children’s rights perspective offers several critical insights. First, children’s rights are rooted in a legal mandate. Second, examining the Trump Administration’s actions from a children’s rights perspective reveals the breadth of rights violations occurring. This more nuanced understanding of the events can help in devising appropriate strategies to respond to such violations. Third, a children’s rights perspective helps place the Trump Administration’s actions in their historical context to better understand the gravity of these actions. Children’s rights law is as close to universally accepted as any human rights law, and thus any departures from such widely embraced standards are particularly revealing. Finally, the authors discuss the implications of this children’s rights assessment, urging action on several fronts to address this harm and prevent violations of children’s rights in the future

Entanglement-enhanced optical gyroscope

Fiber optic gyroscopes (FOG) based on the Sagnac effect are a valuable tool in sensing and navigation and enable accurate measurements in applications ranging from spacecraft and aircraft to self-driving vehicles such as autonomous cars. As with any classical optical sensors, the ultimate performance of these devices is bounded by the standard quantum limit (SQL). Quantum-enhanced interferometry allows us to overcome this limit using non-classical states of light. Here, we report on an entangled-photon gyroscope that uses path-entangled NOON-states (N=2) to provide phase supersensitivity beyond the standard-quantum-limit

The Morphology of Lava Flows in Planetary Environments: Predictions From Analog Experiments

The rates of surface cooling and lateral spreading are evaluated for lava flows on the surface of Earth, Venus, Mars, the Moon, and 10. Differences between the flow morphologies expected in these environments are then predicted under the assumption that the results of recent laboratory simulations oflavas using wax extruded beneath cold water (Fink and Griffiths, 1990) can be carried over. These experiments involved the spreading of viscous liquid under gravity in the presence of a solidifying surface crust and revealed a set of four distinct surface morphologies. Transitions from one morphology to the next occurred in a well-defined sequence when the relative rates of surface solidification and lateral spreading were varied. In comparison with subaerial flows on Earth, the surface of lavas solidifies faster on Venus, where the dense atmosphere provides additional convective heat transfer. Lateral flow oflava is much slower under the smaller gravity of the Moon. Hence, for a given extrusion rate and viscosity, solid crust is predicted to form closer to the vent on both the Moon and Venus than on Earth. Equivalently, faster extrusion rates than those on Earth are required on the Moon, 10, and Venus in order to produce a given surface morphology. A comparison of observed structure, flow rates, and estimated viscosities for some well-documented terrestrial lava flows shows reasonable agreement with the predictions of the model. Extrapolation to extraterrestrial lavas is then illustrated by constraining the effusion rate for a Martian lava flow whose composition is assumed. Spectral information on the chemical composition of Martian flows to be sought by the thermal emission spectrometer on the Mars Observer mission, in conjunction with detailed morphologic observations from the Mars Observer camera, could allow much more accurate estimates of effusion rates for Martian lavas

Reading persuasive texts affects preservice teachers\u27 beliefs about cultural diversity in the classroom

Research has suggested that teachers’ beliefs toward culturally diverse classrooms are affected during teacher education. Text reading, as one of the major learning activities in initial teacher education, is supposed to affect teachers’ educational concepts and beliefs. We conducted two experiments to test the impact of reading a positively or negatively oriented persuasive text about diversity on preservice teachers’ belief change. In Study 1 (N = 42), we found that belief change varied significantly as a function of the direction of the text condition, and that the reading of the texts led to a significantly stronger belief change if the text was in alignment with participants’ prior beliefs. Study 2 (N = 57) revealed a middle-sized but nonsignificant moderator effect for prior knowledge (p = .08, ηp 2 = .06), suggesting that participants with more prior knowledge were less likely to be persuaded by the text. The results provide new insights into factors that may affect the development of preservice teachers’ diversity beliefs. (DIPF/Orig.