Effect of Chemistry on Electrodynamics in the Martian Dynamo Region

Electromagnetic interactions between Mars remnant crustal magnetic fields and solar and planetary ions lead to time and space variations of the ionosphere. In this work, we continue the investigations started by Riousset et al. [2013] and address the effect of chemistry on ion populations in the dynamo region, where ion dynamics are driven by collisions while electrons are still mostly magnetized. We adopt a mesoscale model to simulate dynamics of electrons and ions in the upper atmosphere (100–400 km). Our approach focuses on numerical studies using the Martian Multifluid Magnetohy drodynamic (MF-MHD) Model (M4). The dynamo is a region which varies in time and space due to the lack of a global planetary intrinsic magnetic field, the location of the remnant crustal fields, and the planetary rotation responsible for day/night transition and subsequent trans-terminator particle transfer. The time scales of atmospheric collisions, gyromotions, and chemical processes are discussed in detail to support the selection of relevant reactions for mesoscale studies of the dynamo regions. Several schemes are available in the referenced literature [e.g.,Najib et al.,2011;Brain et al.,2015;Dong et al.,2018], and the chemistry model developed as part of this work is based on Najib et al. [2011]. The improved model more accurately reflects changes in the population of planetary ions, which can alter the dynamo current, thereby also causing perturbations of the magnetic field. The MAVEN mission has shown the importance of ion escape in the Martian atmospheric loss, and previous modeling studies [e.g., Riousset et al., 2014] have shown that electrodynamics in the dynamo region may impact upward transport of ions from this region, supporting the need for further studies. This work shows that the inclusion of chemistry results in substantial changes of ion distributions. Furthermore, differences in the symmetry, strength an altitude range of the dynamo current are observed, likely stemming from the absence of a peak electron density region because of an unbalanced production/destruction of CO+ 2

A Survey of the Structural Determinants of Local Emergency Planning Committee Compliance and Proactivity;Towards an Applied Theory of Precaution in Emergency Management

Millions of factories, chemical facilities, and highways store or convey extremely hazardous substances (EHS) in proximity to populated residential and commercial areas. The proliferation of hazardous chemicals in manufacturing has led to thousands of facilities that store and utilize them throughout the United States. There is inherent risk to neighborhoods and populated areas located near facilities that use and store hazardous chemicals. Local Emergency Planning Committees (LEPCs) were created in 1987 as stakeholder based, primarily volunteer organizations that address hazardous chemical accident mitigation. In addition, LEPCs were mandated with the intent of engaging communities in the debate about hazardous materials. Public safety has also increased in salience in the United States in particular since the terrorist attacks of September 11, 2001 and the 2005 Hurricane Katrina devastation in New Orleans. More recently, the earthquakes in Argentina, Chile, New Zealand, and most notably Japan have refocused efforts worldwide on examining policies and practices surrounding disaster management and response. This dissertation is an examination of compliance and proactivity in LEPCs and how use of limited resources influences these factors. A convenient sample of LEPCs in Ohio was surveyed to gather data for this causally probative study. LEPCs that are more compliant and proactive were expected to be in counties with larger, more urban populations that have more accident experience, and are expected to be in line with disaster management strategies that emphasize public involvement. The results of this study show a positive correlation between number of extremely hazardous substance facilities in a county and the compliance of that county\u27s LEPC. Other findings include limited emphasis on provision of information to the public. Emergency planning resources have been stretched further and further, with additional responsibilities of homeland security in addition to chemical safety tasks, and little to no additio

A Poetry Curriculum for Primary Teachers

This project examined the role of poetry in language development and literacy acquisition in children. The review of current literature strongly supported the rationale for providing poetry experiences beginning at an early age and continuing on through the first few years of school. All stages of language development benefit from exposure to rhythm and rhyme. Poetry can be there to bridge the gap as young children speak their first words, read their first book and write their first sentence. Included is a poetry curriculum centering on the theme of Playground Rhymes. It was specifically written for primary teachers. The research based activities provide children with experience at all levels of language development including oral, phonological awareness, reading, writing, and spelling

A Survey of the Structural Determinants of Local Emergency Planning Committee Compliance and Proactivity;Towards an Applied Theory of Precaution in Emergency Management

Millions of factories, chemical facilities, and highways store or convey extremely hazardous substances (EHS) in proximity to populated residential and commercial areas. The proliferation of hazardous chemicals in manufacturing has led to thousands of facilities that store and utilize them throughout the United States. There is inherent risk to neighborhoods and populated areas located near facilities that use and store hazardous chemicals. Local Emergency Planning Committees (LEPCs) were created in 1987 as stakeholder based, primarily volunteer organizations that address hazardous chemical accident mitigation. In addition, LEPCs were mandated with the intent of engaging communities in the debate about hazardous materials. Public safety has also increased in salience in the United States in particular since the terrorist attacks of September 11, 2001 and the 2005 Hurricane Katrina devastation in New Orleans. More recently, the earthquakes in Argentina, Chile, New Zealand, and most notably Japan have refocused efforts worldwide on examining policies and practices surrounding disaster management and response. This dissertation is an examination of compliance and proactivity in LEPCs and how use of limited resources influences these factors. A convenient sample of LEPCs in Ohio was surveyed to gather data for this causally probative study. LEPCs that are more compliant and proactive were expected to be in counties with larger, more urban populations that have more accident experience, and are expected to be in line with disaster management strategies that emphasize public involvement. The results of this study show a positive correlation between number of extremely hazardous substance facilities in a county and the compliance of that county\u27s LEPC. Other findings include limited emphasis on provision of information to the public. Emergency planning resources have been stretched further and further, with additional responsibilities of homeland security in addition to chemical safety tasks, and little to no additio

Low Voltage Nanoelectromechanical Switches Based on Silicon Carbide Nanowires

We report experimental demonstrations of electrostatically actuated, contact-mode nanoelectromechanical switches based on very thin silicon carbide (SiC) nanowires (NWs). These NWs are lithographically patterned from a 50 nm thick SiC layer heteroepitaxially grown on single-crystal silicon (Si). Several generic designs of in-plane electrostatic SiC NW switches have been realized, with NW widths as small as ~20 nm and lateral switching gaps as narrow as ~10 nm. Very low switch-on voltages are obtained, from a few volts down to ~1 V level. Two-terminal, contact-mode “hot” switching with high on/off ratios (>10^2 or 10^3) has been demonstrated repeatedly for many devices. We find enhanced switching performance in bare SiC NWs, with lifetimes exceeding those based on metallized SiC NWs

Stress-Induced Variations in the Stiffness of Micro- and Nanocantilever Beams

The effect of surface stress on the stiffness of cantilever beams remains an outstanding problem in the physical sciences. While numerous experimental studies report significant stiffness change due to surface stress, theoretical predictions are unable to rigorously and quantitatively reconcile these observations. In this Letter, we present the first controlled measurements of stress-induced change in cantilever stiffness with commensurate theoretical quantification. Simultaneous measurements are also performed on equivalent clamped-clamped beams. All experimental results are quantitatively and accurately predicted using elasticity theory. We also present conclusive experimental evidence for invalidity of the longstanding and unphysical axial force model, which has been widely applied to interpret measurements using cantilever beams. Our findings will be of value in the development of micro- and nanoscale resonant mechanical sensors

Computing Approximate Statistical Discrepancy

Consider a geometric range space (X,A) where X is comprised of the union of a red set R and blue set B. Let Phi(A) define the absolute difference between the fraction of red and fraction of blue points which fall in the range A. The maximum discrepancy range A^* = arg max_{A in (X,A)} Phi(A). Our goal is to find some A^ in (X,A) such that Phi(A^*) - Phi(A^) <= epsilon. We develop general algorithms for this approximation problem for range spaces with bounded VC-dimension, as well as significant improvements for specific geometric range spaces defined by balls, halfspaces, and axis-aligned rectangles. This problem has direct applications in discrepancy evaluation and classification, and we also show an improved reduction to a class of problems in spatial scan statistics

Approximate Maximum Halfspace Discrepancy

Consider the geometric range space (X, H_d) where X ? ?^d and H_d is the set of ranges defined by d-dimensional halfspaces. In this setting we consider that X is the disjoint union of a red and blue set. For each halfspace h ? H_d define a function ?(h) that measures the "difference" between the fraction of red and fraction of blue points which fall in the range h. In this context the maximum discrepancy problem is to find the h^* = arg max_{h ? (X, H_d)} ?(h). We aim to instead find an h? such that ?(h^*) - ?(h?) ? ?. This is the central problem in linear classification for machine learning, in spatial scan statistics for spatial anomaly detection, and shows up in many other areas. We provide a solution for this problem in O(|X| + (1/?^d) log? (1/?)) time, for constant d, which improves polynomially over the previous best solutions. For d = 2 we show that this is nearly tight through conditional lower bounds. For different classes of ? we can either provide a ?(|X|^{3/2 - o(1)}) time lower bound for the exact solution with a reduction to APSP, or an ?(|X| + 1/?^{2-o(1)}) lower bound for the approximate solution with a reduction to 3Sum. A key technical result is a ?-approximate halfspace range counting data structure of size O(1/?^d) with O(log (1/?)) query time, which we can build in O(|X| + (1/?^d) log? (1/?)) time

Practical Low-Dimensional Halfspace Range Space Sampling

We develop, analyze, implement, and compare new algorithms for creating epsilon-samples of range spaces defined by halfspaces which have size sub-quadratic in 1/epsilon, and have runtime linear in the input size and near-quadratic in 1/epsilon. The key to our solution is an efficient construction of partition trees. Despite not requiring any techniques developed after the early 1990s, apparently such a result was never explicitly described. We demonstrate that our implementations, including new implementations of several variants of partition trees, do indeed run in time linear in the input, appear to run linear in output size, and observe smaller error for the same size sample compared to the ubiquitous random sample (which requires size quadratic in 1/epsilon). This result has direct applications in speeding up discrepancy evaluation, approximate range counting, and spatial anomaly detection

Signal Amplification by Sensitive Control of Bifurcation Topology

We describe a novel amplification scheme based on inducing dynamical changes to the topology of a bifurcation diagram of a simple nonlinear dynamical system. We have implemented a first bifurcation-topology amplifier using a coupled pair of parametrically driven high-frequency nanoelectromechanical systems resonators, demonstrating robust small-signal amplification. The principles that underlie bifurcation-topology amplification are simple and generic, suggesting its applicability to a wide variety of physical, chemical, and biological systems