An Evaluation of the History of Aqueous Activity on Mars through a Survey of Select Hypothesized Martian Deltas and Paleolakes via the Analysis of Mineralogy, Morphology, and Thermophysical Properties

Aqueous deposits are an essential key to understanding the geologic/climatic history of water on Mars. The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), High Resolution Imaging Science Experiment (HiRISE), and Thermal Emission Imaging System (THEMIS) have enabled studies of Martian fan deposits in unprecedented detail, including the identification of hydrated minerals (such as phyllosilicates, carbonates, and sulfates) and morphologies consistent with formation in an aqueous environment associated with Martian sedimentary deposits. In this study, twenty-six previously identified fan-shaped deposits (hypothesized as possible deltas) have been examined for hydrated minerals in the beds and distal regions of the deposits. Six deposits have newly been identified to bear phyllosilicates (primarily Fe/Mg-smectites) and are characterized herein with regards to mineralogy, morphology, and thermophysical properties. The results of these analyses suggest that at least four of these deposits are consistent with formation in a deltaic environment; though other possible formation environments, such as alluvial fans and alluvial fan-deltas, should not be altogether excluded, as some of the deposits also bear resemblances to terrestrial examples of such features. The results of this study are consistent with Mars once having hosted aqueous environments in which flowing and standing water was sustainable on the surface, allowing the formation of deltas on Mars

Proton Aurora at Mars: Assessing the Characteristics, Variability, and Driving Mechanisms of a Newly Discovered Phenomenon

The purpose of this doctoral research dissertation is to develop a deeper understanding of the phenomenology, variability and driving processes of proton aurora at Mars. Proton aurora are the most recently discovered of the three types of Martian aurora. Due to Mars’ lack of a global dipole magnetic field, the formation processes of Martian proton aurora are uniquely different than aurora on Earth. Martian proton aurora are expected to form on the planet’s dayside via electron stripping/charge exchange processes between solar wind protons and the neutral hydrogen corona. Herein, I present the results of a study of proton aurora at Mars observed using the Imaging UltraViolet Spectrograph (IUVS) onboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft. Martian proton aurora are observed in IUVS data as a prominent enhancement in the intensity of the hydrogen Lyman-alpha (Ly-α) emission (121.6 nm) between ~110-150 km altitude. Using altitude-intensity profiles from IUVS periapsis limb scan data spanning multiple Martian years, I create a comprehensive database of proton aurora detections and characterize their phenomenology. Based on the results of this study, proton aurora are observed in ~15% of dayside periapsis profiles (with notable seasonal variability), making proton aurora the most commonly observed type of aurora at Mars. The primary factors influencing proton aurora occurrence rates are solar zenith angle (SZA) and season. The highest proton aurora occurrence rates are at low SZAs on the Mars dayside, consistent with known formation processes. Proton aurora have highest emission enhancements, peak intensities, peak altitudes, and occurrence rates (nearing 100%) around southern summer solstice. This time period corresponds with the seasonal inflation of the neutral lower atmosphere, the onset of Martian dust storm season, higher atmospheric temperatures and solar wind flux following perihelion, and seasonally increased coronal hydrogen column densities. I compare remote sensing and in situ observations of Martian proton aurora events. By evaluating concurrent Ly-α emission enhancements and penetrating proton fluxes associated with proton aurora, it is determined that these two parameters generally track with each other, and that discrepancies between the datasets correlate with periods of high dust activity and/or extreme solar events. These discrepancies are caused by a combination of geophysical and observational factors. I also compare proton aurora detections with magnitudes and orientations of the upstream magnetic fields that control the Martian magnetic/plasma environment. I identify a possible preferential influence on Martian proton aurora activity caused by the upstream magnetic field orientations. Numerous types of “atypical” proton aurora are examined, and the causes and variability of these events are constrained. I identify/characterize variations in proton aurora associated with local spatial and temporal variability. And though rare in the IUVS dataset, detections on the planet’s nightside are found to comprise ~4% of all proton aurora observations. The statistical properties of nightside events are quantified and possible formation mechanisms are explored. Lastly, I coordinate a multi-model proton aurora comparison campaign: collaborating with a partnership of ~20 different modelers/scientists at nine different research institutes in the United States and around the world. Through this campaign we develop a better understanding of the physics and driving processes of Martian proton aurora, particularly emphasizing inter-model and data-model comparisons. The results of this doctoral dissertation provide a novel and unprecedented understanding of Martian proton aurora, including the short/long-term variability and primary influencing factors of these unique phenomena

The 3D Quaternary geology of the area around Thornton, Cheshire

This report summarises the superficial (Quaternary) geology of the area around Thornton Science Park at Thornton-Le-Moors in north Cheshire, with an emphasis on understanding the geological units in terms of potential fluid transport through them. The study utilised existing geological maps and borehole records to construct a 3D geological model of the superficial deposits, covering an area of 63km2. The Quaternary succession in the area is dominated by glacigenic sediments, comprising till (gravelly clay), glaciofluvial deposits (gravels and sands) and lesser amounts of glaciolacustrine clays and silts. The tills and glaciofluvial deposits are intercalated in some areas, with intervals of sand and gravel within the till modelled as lenses. The superficial deposits vary laterally and vertically across short distances, making extrapolation difficult in areas where borehole data are absent. Holocene sediments, comprising tidal flat deposits, peat and alluvium occupy the northern part of the study area forms a tract through the middle of the area. The northern part of the model covers the southern bank of the Mersey estuary where tidal flat deposits, dominated by silt and clay, are mapped/modelled with till underneath. A laterally persistent peat layer within the tidal flat deposits is modelled where proven in boreholes. The River Gowy runs south-north through the middle of the model area to join the Mersey at Stanlow Point. An arbitrary mapped line separates alluvium associated with the River Gowy from the Mersey estuary tidal flat deposits, with which they are transitional. A large area of peat is mapped/modelled at surface in a marshy area in the River Gowy floodplain. Boreholes prove that much of this peat is underlain by alluvium. Bedrock is mapped/modelled at surface in isolated patches, representing bedrock ‘highs’ where superficial deposits are locally absent. There may be other unproven zones of thin or absent superficial deposits in the area that could provide direct connectivity from the ground surface to the underlying Sherwood Sandstone Group bedrock

Isogeometric Boundary-Element Analysis for the Wave-Resistance Problem using T-splines

In this paper we couple collocated Boundary Element Methods (BEM) with unstructured analysis suitable T-spline surfaces for solving a linear Boundary Integral Equation (BIE) arising in the context of a ship-hydrodynamic problem, namely the so-called Neumann-Kelvin problem, following the formulation by Brard (1972) [1] and Baar & Price (1988) [2]. The local-refinement capabilities of the adopted T-spline bases, which are used for representing both the geometry of the hull and approximating the solution of the associated BIE, in accordance with the Isogeometric concept proposed by Hughes et al. (2005) [3], lead to a solver that achieves the same error level for many fewer degrees of freedom as compared with the corresponding NURBS-based Isogeometric-BEM solver recently developed in Belibassakis et al. (2013) [4]. In this connection, this paper makes a step towards integrating modern CAD representations for ship-hulls with hydrodynamic solvers of improved accuracy and efficiency, which is a prerequisite for building efficient ship-hull optimizers

An adaptive inelastic magnetic mirror for Bose-Einstein condensates

We report the reflection and focussing of a Bose-Einstein condensate by a new pulsed magnetic mirror. The mirror is adaptive, inelastic, and of extremely high optical quality. The deviations from specularity are less than 0.5 mrad rms, making this the best atomic mirror demonstrated to date. We have also used the mirror to realize the analog of a beam-expander, producing an ultra-cold collimated fountain of matter wavesComment: 4 pages, 4 figure

Haloperidol and Ziprasidone for Treatment of Delirium in Critical Illness

BACKGROUND: There are conflicting data on the effects of antipsychotic medications on delirium in patients in the intensive care unit (ICU). METHODS: In a randomized, double-blind, placebo-controlled trial, we assigned patients with acute respiratory failure or shock and hypoactive or hyperactive delirium to receive intravenous boluses of haloperidol (maximum dose, 20 mg daily), ziprasidone (maximum dose, 40 mg daily), or placebo. The volume and dose of a trial drug or placebo was halved or doubled at 12-hour intervals on the basis of the presence or absence of delirium, as detected with the use of the Confusion Assessment Method for the ICU, and of side effects of the intervention. The primary end point was the number of days alive without delirium or coma during the 14-day intervention period. Secondary end points included 30-day and 90-day survival, time to freedom from mechanical ventilation, and time to ICU and hospital discharge. Safety end points included extrapyramidal symptoms and excessive sedation. RESULTS: Written informed consent was obtained from 1183 patients or their authorized representatives. Delirium developed in 566 patients (48%), of whom 89% had hypoactive delirium and 11% had hyperactive delirium. Of the 566 patients, 184 were randomly assigned to receive placebo, 192 to receive haloperidol, and 190 to receive ziprasidone. The median duration of exposure to a trial drug or placebo was 4 days (interquartile range, 3 to 7). The median number of days alive without delirium or coma was 8.5 (95% confidence interval [CI], 5.6 to 9.9) in the placebo group, 7.9 (95% CI, 4.4 to 9.6) in the haloperidol group, and 8.7 (95% CI, 5.9 to 10.0) in the ziprasidone group (P=0.26 for overall effect across trial groups). The use of haloperidol or ziprasidone, as compared with placebo, had no significant effect on the primary end point (odds ratios, 0.88 [95% CI, 0.64 to 1.21] and 1.04 [95% CI, 0.73 to 1.48], respectively). There were no significant between-group differences with respect to the secondary end points or the frequency of extrapyramidal symptoms. CONCLUSIONS: The use of haloperidol or ziprasidone, as compared with placebo, in patients with acute respiratory failure or shock and hypoactive or hyperactive delirium in the ICU did not significantly alter the duration of delirium. (Funded by the National Institutes of Health and the VA Geriatric Research Education and Clinical Center; MIND-USA ClinicalTrials.gov number, NCT01211522 .)

Super D-branes from BRST Symmetry

Recently a new formalism has been developed for the covariant quantization of superstrings. We study properties of Dp-branes and p-branes in this new framework, focusing on two different topics: effective actions and boundary states for Dp-branes. We present a derivation of the Wess-Zumino terms for super (D)p-branes using BRST symmetry. To achieve this we derive the BRST symmetry for superbranes, starting from the approach with/without pure spinors, and completely characterize the WZ terms as elements of the BRST cohomology. We also develope the boundary state description of Dp-branes by analyzing the boundary conditions for open strings in the completely covariant (i.e., without pure spinors) BRST formulation.Comment: 31 pp; journal version, expended discussion of D-brane pure spinor constraints in Section 2.

Linear and Second-order Optical Response of the III-V Mono-layer Superlattices

We report the first fully self-consistent calculations of the nonlinear optical properties of superlattices. The materials investigated are mono-layer superlattices with GaP grown on the the top of InP, AlP and GaAs (110) substrates. We use the full-potential linearized augmented plane wave method within the generalized gradient approximation to obtain the frequency dependent dielectric tensor and the second-harmonic-generation susceptibility. The effect of lattice relaxations on the linear optical properties are studied. Our calculations show that the major anisotropy in the optical properties is the result of strain in GaP. This anisotropy is maximum for the superlattice with maximum lattice mismatch between the constituent materials. In order to differentiate the superlattice features from the bulk-like transitions an improvement over the existing effective medium model is proposed. The superlattice features are found to be more pronounced for the second-order than the linear optical response indicating the need for full supercell calculations in determining the correct second-order response.Comment: 9 pages, 4 figures, submitted to Phy. Rev.