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Full-Text Articles in Physics
Electrical Characterization Of Gel Collected From Shark Electrosensors, Brandon R. Brown
Electrical Characterization Of Gel Collected From Shark Electrosensors, Brandon R. Brown
Physics and Astronomy
To investigate the physical mechanism of the electric sense, we present an intial electrical characterization of the glycoprotein gel that fills the electrosensitive organs of marine elasmobranchs (sharks, skates, and rays). We have collected samples of this gel, postmortem, from three shark species, and removed the majority of dissolved salts in one sample via dialysis. Here we present the results of dc conductivity measurements, low-frequency impedance spectroscopy, and electrophoresis. Electrophoresis shows a range of large protein-based molecules fitting the expectations of glycoproteins, but the gels of different species exhibit litttle similarity. The electrophoresis signature is unaffected by thermal cycling and …
Renormalized Path Integral For The Two-Dimensional Δ-Function Interaction, Horacio E. Camblong
Renormalized Path Integral For The Two-Dimensional Δ-Function Interaction, Horacio E. Camblong
Physics and Astronomy
A path-integral approach for δ-function potentials is presented. Particular attention is paid to the two-dimensional case, which illustrates the realization of a quantum anomaly for a scale-invariant problem in quantum mechanics. Our treatment is based on an infinite summation of perturbation theory that captures the nonperturbative nature of the δ-function bound state. The well-known singular character of the two-dimensional δ-function potential is dealt with by considering the renormalized path integral resulting from a variety of schemes: dimensional, momentum-cutoff, and real-space regularization. Moreover, compatibility of the bound-state and scattering sectors is shown.
Coherent Integration Of 0.5 Ghz Spectral Holograms At 1536 Nm Using Dynamic Biphase Codes, Z Cole, Thomas Böttger, R Krishna Mohan, R Reibel, W R. Babbitt, R L. Cone, K D. Merkel
Coherent Integration Of 0.5 Ghz Spectral Holograms At 1536 Nm Using Dynamic Biphase Codes, Z Cole, Thomas Böttger, R Krishna Mohan, R Reibel, W R. Babbitt, R L. Cone, K D. Merkel
Physics and Astronomy
Spectral hole-burning-based optical processing devices are proposed for coherent integration of multiple high-bandwidth interference patterns in a spectral hole-burning medium. In this implementation, 0.5 GHz spectral holographic gratings are dynamically accumulated in Er3+:Y2SiO5" style="position: relative;" tabindex="0" id="MathJax-Element-1-Frame">Er3+:Y2SiO5 at 4.2 K using a 1536 nm laser frequency stabilized to a spectral hole, along with commercial off-the-shelf components. The processed data, representing time delays over 0.5–2.0 μs, were optically read out using a frequency-swept probe; this approach makes possible the use of low-bandwidth, large-dynamic-range detectors and digitizers and enables competitive processing for applications such as radar,lidar, and radio astronomy. Coherent integration …
Mutual Constraints Between Reionization Models And Parameter Extraction From Cosmic Microwave Background Data, Aparna Venkatesan
Mutual Constraints Between Reionization Models And Parameter Extraction From Cosmic Microwave Background Data, Aparna Venkatesan
Physics and Astronomy
Spectroscopic studies of high-redshift objects and increasingly precise data on the cosmic microwave background (CMB) are beginning to independently place strong complementary bounds on the epoch of hydrogen reionization. Parameter estimation from current CMB data continues, however, to be subject to several degeneracies. Here, we focus on those degeneracies in CMB parameter forecasts related to the optical depth to reionization. We extend earlier work on the mutual constraints that such analyses of CMB data and a reionization model may place on each other to a more general parameter set and to the case of data anticipated from the MAP satellite. …
Modeling An Electrosensory Landscape: Behavioral And Morphological Optimization In Elasmobranch Prey Capture, Brandon R. Brown
Modeling An Electrosensory Landscape: Behavioral And Morphological Optimization In Elasmobranch Prey Capture, Brandon R. Brown
Physics and Astronomy
Most biological sensory systems benefit from multiple sensors. Elasmobranchs (sharks, skates and rays) possess an array of electroreceptive organs that facilitate prey location, mate location and navigation. Here, the perceived electrosensory landscape for an elasmobranch approaching prey is mathematically modeled. The voltages that develop simultaneously in dozens of separate sensing organs are calculated using electrodynamics. These voltages lead directly to firing rate modifications in the primary afferent nerves. The canals connecting the sense organs to an elasmobranch's surface exhibit great variation of location and orientation. Here, the voltages arising in the sense organs are found to depend strongly on the …