3,413 research outputs found

    Plasmonic edge states: an electrostatic eigenmode description

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    We consider periodic arrangements of metal nanostructures and study the effect of periodicity on the localised surface plasmon resonance of the structures within an electrostatic eigenmode approximation. We show that within this limit, the collective surface plasmon resonances of the periodic structures can be expressed in terms of superpositions of the eigenmodes of uncoupled nanostructures that exhibit a standing--wave character delocalised across the entire periodic structure. The formalism derived successfully enables the design and accounts for the observation of plasmonic edge-states in periodic structures

    Global Stratigraphy and the Fossil Record Validate a Flood Origin for the Geologic Column

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    The geologic column has been under the scrutiny of numerous creationists for many decades. Critics have claimed the column is intimately tied to the evolutionary worldview and deep time, and cannot be trusted or used by creation scientists. Other creation scientists have argued that the geologic column, although incomplete at most locations, can provide useful correlations of rocks and fossils across the globe. This paper examines the sedimentary rocks across three continents in an attempt to test the validity of the global geologic column. We attempted to assess the data primarily from a lithologic viewpoint, and as independent of the fossil data as possible. To accomplish this, we constructed a new data set of over 1500 local, stratigraphic columns across three continents, recording the detailed lithologic information and Sloss-type megasequence boundaries at each site. A detailed 3-D lithology model was created for each continent using the local columns. We also constructed maps of the basal lithology for each megasequence. Unique lithologic units, like salt and chert-rich layers were also tracked from column to column. Results show extensive lithologic units (i.e. blanket sandstones) covered portions of every continent and are correlative across vast regions and even continent to continent. The correlation of these stacked basal megasequence units, and other unique lithologies (i.e. salt and chert layers) within the megasequences, confirm the validity of the geologic column on a global scale. The observable pattern in the fossil record further confirms these findings. Indeed, a global Flood could produce globally extensive, stacked lithologic units on an intercontinental scale. Creationists should not be critical of the geologic column, but embrace it as evidence of a global Flood event

    Use of Sedimentary Megasequences to Re-create Pre-Flood Geography

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    Knowledge of pre-Flood geography and the location of the Garden of Eden have eluded Bible-believing scientists and theologians. This study attempts to reconstruct the gross geography of the pre-Flood world by examining the detailed stratigraphy that was deposited during the Flood. Over 1500 stratigraphic columns were constructed across North and South America and Africa, recording the lithology and stratigraphy at each location. Sedimentary layers were examined using Sloss-type megasequences which allowed detailed analysis of the progression of the Flood in six discrete depositional segments. The three earliest megasequences, Sauk, Tippecanoe and Kaskaskia, were the most limited in areal coverage and volume and contain almost exclusively marine fossils, indicating a likely marine realm. The 4th megasequence (Absaroka) shows a dramatic increase in global coverage and volume and includes the first major plant and terrestrial animal fossils. The 5th megasequence (Zuni) appears to be the highest water point of the Flood (Day 150) as it exhibits the maximum global volume of sediment and the maximum areal coverage, compared to all earlier megasequences. The final megasequence (Tejas) exhibits fossils indicative of the highest upland areas of the pre-Flood world. Its rocks document a major shift in direction reflective of the receding water phase of the Flood. Results include the first, data-based, pre-Flood geography map for half of the world. By comparing the individual megasequences to the fossil record, patterns emerge that fit the concept of ecological zonation. The paper concludes with a new ecological zonation-megasequence model for Flood strata and the fossil record

    Optical chirality from dark-field illumination of planar plasmonic nanostructures

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    Dark-field illumination is shown to make planar chiral nanoparticle arrangements exhibit circular dichroism in extinction analogous to true chiral scatterers. Circular dichrosim is experimentally observed at the maximum scattering of single oligomers consisting rotationally symmetric arrangements of gold nanorods, with strong agreement to numerical simulation. A dipole model is developed to show that this effect is caused by a difference in the geometric projection of a nanorod onto the handed orientation of electric fields created by a circularly polarized dark-field that is normally incident on a glass substrate. Owing to this geometric origin, the wavelength of the peak chiral response is also experimentally shown to shift depending on the separation between nanoparticles. All presented oligomers have physical dimensions less than the operating wavelength, and the applicable extension to closely packed planar arrays of oligomers is demonstrated to amplify the magnitude of circular dichroism. The realization of strong chirality in these oligomers demonstrates a new path to engineer optical chirality from planar devices using dark-field illumination

    Labeless and reversible immunosensor assay based upon an electrochemical current-transient protocol

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    A novel labeless and reversible immunoassay based upon an electrochemical current-transient protocol is reported which offers many advantages in comparison to classical immuno-biochemical analyses in terms of simplicity, speed of response, reusability and possibility of multiple determinations. Conducting polypyrrole films containing antibodies against 1) Bovine Serum Albumin (BSA) and 2) Digoxin were deposited on the surface of platinum electrodes to produce conductive affinity matrices having clearly defined binding characteristics. The deposition process has been investigated using 125I labelled anti-digoxin to determine optimal fabrication protocols. Antibody integrity and activity, together with non-specific binding of antigen on the conducting matrix have also been investigated using tritiated digoxin to probe polypyrrole/anti-digoxin films. Amperometric responses to digoxin were recorded in flow conditions using these films, but the technique was limited in use mainly due to baseline instability. Anti-BSA - polypyrrole matrices were investigated in more detail in both flow and quiescent conditions. No observable response was found in flow conditions, however under quiescent conditions (in non-stirred batch cell), anti-BSA – polypyrrole films have been demonstrated to function as novel quantitative chronoamperometric immuno-biosensors when interrogated using a pulsed potential waveform. The behaviour of the electrodes showed that the antibody/antigen binding and/or interaction process underlying the response observed was reversible in nature, indicating that the electrodes could be used for multiple sensing protocols. Calibration profiles for BSA demonstrated linearity for a concentration range of 0-50 ppm but tended towards a plateau at higher concentrations. Factors relating to replicate sensor production, sample measurement and reproducibility are discuss

    Introduction

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    It didn\u27t seem so wrong. It seemed as though I worked my whole life to get where I am, and at the same time, when it was presented to me, it was like this was the time I could start to get back some of the fruits of my labor. 1 —Paul Palmer, former star college football running back, regarding cash payments of more than 5,000hereceivedwhileacollegeseniorfromsportsagentNorbyWalters.Thisepigraphhasremainedinourtextthroughmultipleeditions.Itscontinuedrelevanceisunderscoredbytheironythat,inarecentcourtruling,ajudgepeggedtheminimumdollarfigureforcollegeathletestoreceivedfromlicensingrevenuesat5,000 he received while a college senior from sports agent Norby Walters. This epigraph has remained in our text through multiple editions. Its continued relevance is underscored by the irony that, in a recent court ruling, a judge pegged the minimum dollar figure for college athletes to received from licensing revenues at 5,000. This book, meanwhile, focuses on the evolving sports agent industry, the issues affecting it, and how to improve and regulate it. Key issues and problems associated with sports agents are visible at the high school, collegiate, and professional levels. Whatever the concerns that lie at the center of the sports agent storm, it is a business that captures the attention of many
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