Quaternary geology of Sargent County, North Dakota

Sargent County, in southeastern North Dakota, was glaciated during the Pleistocene Epoch. Objectives of a study of Sargent County were to (1) describe the surface sediment and interpret its origin, (2) correlate, where possible, this sediment with that of adjacent areas, and (3) recon struct the general geologic history of the county for the Quaternary Period. A geologic map of the county was prepared using field data, topo graphic maps, aerial stereopairs, and soil maps. A map showing surface sediment origin was subsequently made using the available field and laboratory information. Most of Sargent County is typical rolling prairie underlain by Quaternary sediment resting unconformably on Mesozoic rocks. The Quaternary sediment is primarily nonindurated sediment belonging to the Coleharbor and Walsh Formations. The Mesozoic rocks are mostly well-indurated sediment belonging to the Pierre, Niobrara, Carlile, Greenhorn, Belle Fourche, Howry, Newcastle, and Skull Creek Formations. The Coleharbor Formation comprises about 95 percent of the county surface area and is primarily glacial sediment. The Formation includes five facies: diamicton (glacial sediment); sand and gravel (fluvial channel sediment); silt (lacustrine sediment); silty clay (lacustrine sediment); and silt, sand, silty sand, and clay (turbidity-current sediment). The Walsh Formation comprises the remaining 5 percent of the county and includes four facies: clay (lacustrine sediment), sandy silt (slope wash sediment), clayey silt (fluvial overbank sediment), and silty sand (eolian sediment). Evidence of previous glacier advances includes: (1) the occurrence of two different drift units exposed in a roadcut on the. Prairie Coteau, (2) the morphology and structure of the Whitestone Hills, and (3) the morphology and stratigraphy of the Lake Oakes Hills. Two glacial diamicton beds are exposed in a Prairie Coteau roadcut; the upper bed, Drift A, is noticeably rich in shale fragments whereas the lower bed, Drift B, is shale-poor. Drift A correlates with the upper member of the Red Lake Falls Formation on the upper Red River Valley and the New Ulm Till of southwestern Minnesota. The shale fragments in Drift A were eroded by a glacier that moved down the valleys on the Red and Minnesota Rivers. The small percentage of shale fragments in Drift B indicates that it was deposited by a glacier that moved southward along the axis of the Red Lakes lowland, where there is little shale bedrock to erode. Drift B correlates with the lower member of the Red Lake Falls Formation of the upper Red River Valley and the Granite Falls Till of southwestern Minnesota. The Whitestone Hills are streamlined and probably represent an over ridden landfonn from a previous glacier advance, as evidenced by oxidized diamicton occurring beneath unoxidized diamicton, separated by fluvial sand and gravel. The Lake Oakes Hills in western Sargent County were found to be primarily composed of turbidity-current sediment that was deposited in an ice-marginal lake called Lake Oakes. Lake Oakes predates the last advance of ice because the hills are veneered with glacial diamicton deposited during overriding of the hills by the last glacier advance. The Lake Oakes sediment overlies another glacial diamicton evidently de posited by an earlier glacial advance. The geologic events of the last glacial advance and ensuring de glaciation can be subdivided into three phases. During Phase 1, ice moved southward along the lowland of the Red and Minnesota Rivers. The Prairie Coteau caused the glacier to split into the James and Des Moines Lobes. Climatic warming caused the glacier to thin and retreat. The presence of stagnant ice in Sargent County CTarks the beginning of Phase 2. Melt water from the James River in Dickey County and other streams in Sargent County and adjacent areas drained southward into South Dakota where it was eventually ponded by an end-moraine complex, result ing in the formation of glacial Lake Dakota. The lake eventually reached to several miles north of Cogswell in Sargent County. Glacier ice was no longer active in Sargent County by the: beginning of Phase 3. Stiperglacial debris covered stagnant ice over most of the county, however, insulating it from rapid melting. Melt water discharged into glacial Lake Agassiz in the Red River Valley during this phase. Lake silt was deposited on stagnant ice above the Herman Beach level in Sargent County during the Milnor subphase. The lake dropped to the Herman level · (1,060 feet) during the Herman subphase and overflow from the Sheyenne River cut across northeastern Sargent County during the subsequent Milnor Channel subphase. All glacier ice in Sargent County was gone by 10,000 B.P. The climate continued to warm resulting in a vegetative succession from forest to prairie. The increased dryness resulted in increased stream and wind erosion. Between 7,000 and 8,000 years B.P. maximum dryness was reached; resulting eolian activity produced dunes in some sandy and silty parts. of the county. From 7,000 until 4,000 years B.P. the climate gradually cooled. Since 4,000 years B.P. the climate of Sargent County has been relatively uniform

Evolutions of Magnetized and Rotating Neutron Stars

We study the evolution of magnetized and rigidly rotating neutron stars within a fully general relativistic implementation of ideal magnetohydrodynamics with no assumed symmetries in three spatial dimensions. The stars are modeled as rotating, magnetized polytropic stars and we examine diverse scenarios to study their dynamics and stability properties. In particular we concentrate on the stability of the stars and possible critical behavior. In addition to their intrinsic physical significance, we use these evolutions as further tests of our implementation which incorporates new developments to handle magnetized systems.Comment: 12 pages, 8 figure

Relativistic MHD with Adaptive Mesh Refinement

This paper presents a new computer code to solve the general relativistic magnetohydrodynamics (GRMHD) equations using distributed parallel adaptive mesh refinement (AMR). The fluid equations are solved using a finite difference Convex ENO method (CENO) in 3+1 dimensions, and the AMR is Berger-Oliger. Hyperbolic divergence cleaning is used to control the $\nabla\cdot {\bf B}=0$ constraint. We present results from three flat space tests, and examine the accretion of a fluid onto a Schwarzschild black hole, reproducing the Michel solution. The AMR simulations substantially improve performance while reproducing the resolution equivalent unigrid simulation results. Finally, we discuss strong scaling results for parallel unigrid and AMR runs.Comment: 24 pages, 14 figures, 3 table

Fifteen years of XMM-Newton and Chandra monitoring of Sgr A*: Evidence for a recent increase in the bright flaring rate

We present a study of the X-ray flaring activity of Sgr A* during all the 150 XMM-Newton and Chandra observations pointed at the Milky Way center over the last 15 years. This includes the latest XMM-Newton and Chandra campaigns devoted to monitoring the closest approach of the very red Br-Gamma emitting object called G2. The entire dataset analysed extends from September 1999 through November 2014. We employed a Bayesian block analysis to investigate any possible variations in the characteristics (frequency, energetics, peak intensity, duration) of the flaring events that Sgr A* has exhibited since their discovery in 2001. We observe that the total bright-or-very bright flare luminosity of Sgr A* increased between 2013-2014 by a factor of 2-3 (~3.5 sigma significance). We also observe an increase (~99.9% significance) from 0.27+-0.04 to 2.5+-1.0 day^-1 of the bright-or-very bright flaring rate of Sgr A*, starting in late summer 2014, which happens to be about six months after G2's peri-center passage. This might indicate that clustering is a general property of bright flares and that it is associated with a stationary noise process producing flares not uniformly distributed in time (similar to what is observed in other quiescent black holes). If so, the variation in flaring properties would be revealed only now because of the increased monitoring frequency. Alternatively, this may be the first sign of an excess accretion activity induced by the close passage of G2. More observations are necessary to distinguish between these two hypotheses.Comment: Accepted for publication in MNRA

Operationally Invariant Measure of the Distance between Quantum States by Complementary Measurements

We propose an operational measure of distance of two quantum states, which conversely tells us their closeness. This is defined as a sum of differences in partial knowledge over a complete set of mutually complementary measurements for the two states. It is shown that the measure is operationally invariant and it is equivalent to the Hilbert-Schmidt distance. The operational measure of distance provides a remarkable interpretation of the information distance between quantum states.Comment: 4 page

Who the hell was that? Stories, bodies and actions in the world

This article explores a two-way relationship between stories and the experiential actions of bodies in the world. Through an autoethnographic approach, the article presents a series of interlinked story fragments in an effort to show and evoke a feel for the ways in which stories, bodies, and actions influence and shape each other over time. It offers some reflections on the experiences the stories portray from the perspective of a social constructionist conception of narrative theory and suggest that while stories exert a powerful influence on the actions of our bodies, our bodies intrude on or ‘talk back’ to this process because bodies have an existence beyond stories

The Milli-Motein: A self-folding chain of programmable matter with a one centimeter module pitch

The Milli-Motein (Millimeter-Scale Motorized Protein) is ca chain of programmable matter with a 1 cm pitch. It can fold itself into digitized approximations of arbitrary three-dimensional shapes. The small size of the Milli-Motein segments is enabled by the use of our new electropermanent wobble stepper motors, described in this paper, and by a highly integrated electronic and mechanical design. The chain is an interlocked series of connected motor rotors and stators, wrapped with a continuous flex circuit to provide communications, control, and power transmission capabilities. The Milli-Motein uses off-the-shelf electronic components and fasteners, and custom parts fabricated by conventional and electric discharge machining, assembled with screws, glue, and solder using tweezers under a microscope. We perform shape reconfiguration experiments using a four-segment Milli-Motein. It can switch from a straight line to a prescribed shape in 5 seconds, consuming 2.6 W power during reconfiguration. It can hold its shape indefinitely without power. During reconfiguration, a segment can lift the weight of one but not two segments as a horizontal cantilever.United States. Defense Advanced Research Projects Agency. Programmable Matter ProgramUnited States. Defense Advanced Research Projects Agency. Maximum Mobility and Manipulation (M3) ProgramUnited States. Army Research Office (Grant W911NF-08-1-0254)United States. Army Research Office (Grant W911NF-11-1-0096)Massachusetts Institute of Technology. Center for Bits and Atom

Computational continuum modeling of solder interconnects: Applications

The most commonly used solder for electrical interconnections in electronic packages is the near eutectic 60Sn-40Fb alloy. This alloy has a number of processing advantages (suitable melting point of 183C and good wetting behavior). However, under conditions of cyclic strain and temperature (thermomechanical fatigue), the microstructure of this alloy undergoes a heterogeneous coarsening and failure process that makes the prediction of solder joint lifetime complex. A viscoplastic, microstructure dependent, constitutive model for solder, which is currently under development, was implemented into a finite element code. With this computational capability, the thermomechanical response of solder interconnects, including microstructural evolution, can be predicted. This capability was applied to predict the thermomechanical response of a mini ball grid array solder interconnect. In this paper, the constitutive model will first be briefly discussed. The results of computational studies to determine the thermomechanical response of a mini ball grid array solder interconnects then will be presented

Life prediction modeling of solder interconnects for electronic systems

A microstructurally-based computational simulation is presented that predicts the behavior and lifetime of solder interconnects for electronic applications. This finite element simulation is based on an internal state variable constitutive model that captures both creep and plasticity, and accounts for microstructural evolution. The basis of the microstructural evolution is a simple model that captures the grain size and microstructural defects in the solder. The mechanical behavior of the solder is incorporated into the model in the form of time-dependent viscoplastic equations derived from experimental creep tests. The unique aspect of this methodology is that the constants in the constitutive relations of the model are determined from experimental tests. This paper presents the constitutive relations and the experimental means by which the constants in the equations are determined. The fatigue lifetime of the solder interconnects is predicted using a damage parameter (or grain size) that is an output of the computer simulation. This damage parameter methodology is discussed and experimentally validated