SH-WAVE REFRACTION AND REFLECTION INVESTIGATION OF QUATERNARY GEOLOGY―CENTRAL UNITED STATES SEISMIC OBSERVATORY

The Central United States Seismic Observatory (CUSSO) consists of an array of vertical strong motion accelerometers and medium period seismometers that penetrate 585 m into the Mississippi Embayment sediments and terminates into Paleozoic bedrock. The array is located in the New Madrid Seismic Zone within the upper embayment. The thick unconsolidated Quaternary sediments have the potential to influence strong motions; understanding how these sediments affect ground motion is the goal of the CUSSO array. Nine SH-wave refraction and five P-wave common midpoint reflection surveys were collected within a 1 km radius around the CUSSO borehole in order to characterize the local seismic stratigraphy. Three major seismic boundaries from SH-wave refraction and six P-wave continuous reflection boundaries were interpreted. Combined, both methods were used to characterize seismic horizons (Quaternary to Paleozoic) around the CUSSO in terms of velocity and depth. Faults in the area are subparallel and northeast-southwest trending. Some faults appear to deform Eocene and Quaternary sediments, although no surface expression has been found

KMS conditions for 4-point Green functions at finite temperature

We study the 4-point function in the Keldysh formalism of the closed time path formulation of real time finite temperature field theory. We derive the KMS conditions for these functions and discuss the number of 4-point functions that are independent. We define a set of `physical' functions which are linear combinations of the usual Keldysh functions. We show that these functions satisfy simple KMS conditions. In addition, we consider a set of integral equations which represent a resummation of ladder graphs. We show that these integral equations decouple when one uses the physical functions that we have defined. We discuss the generalization of these results to QED.Comment: 17 pages in Revtex with 2 figure

Photodegradation of FD&C Red No. 40 Dye in Synthetic Hummingbird Nectar

It is common among many homeowners and bird enthusiasts alike to provide supplemental nutrition for Hummingbirds through nectar feeder set-ups. Often commercially available nectar powders and concentrates contain a variety of red dyes solely to make the nectar look more appealing for the customer. Based on the lack of information regarding the safety of the dyes for the birds, investigation into how FD&C red #40 (the most common red dye) degrades in a sucrose solution exposed to sunlight is warranted. Ultra High Pressure Liquid Chromatography and mass spectrometry were used to identify the chemical structure of FD&C Red #40 and determine ideal ppm concentrations for best analysis of potential metabolites. Ultimately, degradation of dye in the presence of controlled artificial sunlight in a sucrose solution (~25% sucrose) and subsequent analysis will help to determine the degraded metabolites that arise and gain insight into their potential harm to hummingbirds.https://digitalcommons.lmu.edu/cures_posters/1008/thumbnail.jp

QED Electrical Conductivity using the 2PI Effective Action

In this article we calculate the electrical conductivity in QED using the 2PI effective action. We use a modified version of the usual 2PI effective action which is defined with respect to self-consistent solutions of the 2-point functions. We show that the green functions obtained from this modified effective action satisfy ward identities and that the conductivity obtained from the kubo relation is gauge invariant. We work to 3-loop order in the modified 2PI effective action and show explicitly that the resulting expression for the conductivity contains the square of the amplitude that corresponds to all binary collision and production processes.Comment: 24 pages, 21 figure

Interspecific comparison of hydrodynamic performance and structural properties among intertidal macroalgae

Macroalgae use flexibility and reconfiguration, i.e. the alteration of shape, size and orientation as water velocity increases, to reduce the hydrodynamic forces imposed in the wave-swept rocky intertidal zone. Quantifying the effects of flexibility on hydrodynamic performance is difficult, however, because the mechanisms of reconfiguration vary with water velocity and the relationship between algal solid mechanics and hydrodynamic performance is poorly understood. In this study, the hydrodynamic performance, morphology and solid mechanics of 10 rocky shore macroalgal species were quantified to evaluate the influences of flexibility and morphology on reconfiguration. Hydrodynamic performance was measured in a flume by direct measurement of changes in size and shape during reconfiguration across a wide range of velocities, material stiffness was quantified with standard materials testing, and structural properties were calculated from material and morphological data. Hydrodynamic parameters varied significantly among species, indicating variation in the magnitude of reconfiguration and the velocities required for full reconfiguration. Structural properties also varied among species, and were correlated with hydrodynamic performance in some instances. The relationship between hydrodynamic and structural properties is velocity dependent, such that flexibility influences different aspects of reconfiguration at low and high velocities. Groups are identifiable among species based on hydrodynamic and structural properties, suggesting that these properties are useful for addressing functional-form hypotheses and the effects of hydrodynamic disturbance on macroalgal communities

The hydrodynamic effects of shape and size change during reconfiguration of a flexible macroalga

Rocky intertidal organisms experience large hydrodynamic forces due to high water velocities created by breaking waves. Flexible organisms, like macroalgae, often experience lower drag than rigid organisms because their shape and size change as velocity increases. This phenomenon, known as reconfiguration, has been previously quantified as Vogel\u27s E, a measure of the relationship between velocity and drag. While this method is very useful for comparing reconfiguration among organisms it does not address the mechanisms of reconfiguration, and its application to predicting drag is problematic. The purpose of this study was twofold: (1) to examine the mechanisms of reconfiguration by quantifying the change in shape and size of a macroalga in flow and (2) to build a mechanistic model of drag for reconfiguring organisms. Drag, frontal area and shape of the intertidal alga Chondrus crispus were measured simultaneously in a recirculating flume at water velocities from 0 to ∼2 m s–1. Reconfiguration was due to two separate mechanisms: whole-alga realignment (deflection of the stipe) at low velocities (\u3c0.2 m s–1) and compaction of the crown (reduction in frontal area and change in shape) at higher velocities. Change in frontal area contributed more to drag reduction than change in drag coefficient. Drag coefficient and frontal area both decrease exponentially with increasing water velocity, and a mechanistic model of drag was developed with explicit functions to describe these changes. The model not only provides mechanistic parameters with which to compare reconfiguration among individuals and species, but also allows for more reliable predictions of drag at high, ecologically relevant water velocities

Ward Identities in Non-equilibrium QED

We verify the QED Ward identity for the two- and three -point functions at non-equilibrium in the HTL limit. We use the Keldysh formalism of real time finite temperature field theory. We obtain an identity of the same form as the Ward identity for a set of one loop self-energy and one loop three-point vertex diagrams which are constructed from HTL effective propagators and vertices.Comment: 19 pages, RevTex, 4 PostScript figures, revised version to be published in Phys. Rev.