Publications by authors named "JJ Simpson"

A design challenge for photodiodes yielding both high speed and responsivity is the necessity to concentrate incident light into a subwavelength active volume region. Photonic nanojets have been reported in the literature as a means to focus an incident plane wave to a subwavelength-waist propagating beam with applications ranging from next-generation DVDs to characterizing subwavelength features within dielectric targets. In the present work, a new application of photonic nanojets is proposed, focusing electromagnetic energy into a photodiode.

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Photonic nanojets have been previously shown (both theoretically and experimentally) to be highly sensitive to the presence of an ultra-subwavelength nanoscale particle within the nanojet. In the present work, photonic nanojets elongated by almost an order of magnitude (relative to the latest previously published work) are found to possess another key characteristic: they are sensitive to the presence of ultra-subwavelength nanoscale thin features embedded within a dielectric object. This additional characteristic of photonic nanojets is demonstrated through comparisons between fundamentally different 3-D and corresponding 1-D full Maxwell's equations finite-difference time-domain (FDTD) models.

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The Sudbury Neutrino Observatory (SNO) used an array of 3He proportional counters to measure the rate of neutral-current interactions in heavy water and precisely determined the total active (nu_x) 8B solar neutrino flux. This technique is independent of previous methods employed by SNO. The total flux is found to be 5.

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This Letter presents a scattered-field formulation for modeling dispersive media using the finite-difference time-domain (FDTD) method. Specifically, the auxiliary differential equation method is applied to Drude and Lorentz media for a scattered field FDTD model. The present technique can also be applied in a straightforward manner to Debye media.

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We theoretically investigate light scattering from a bi-sphere system consisting of a gold nanosphere and a lossless dielectric microsphere illuminated at a resonant optical wavelength of the microsphere. Using generalized multisphere Mie theory, we find that a gold nanosphere 100 times smaller than the dielectric microsphere can be detected with a subdiffraction resolution as fine as one-third wavelength in the background medium when the microsphere is illuminated at a Mie resonance. Otherwise, off-resonance, the spatial resolution reverts to that of the nonresonant nanojet, approximately one-half wavelength in the background medium.

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The Sudbury Neutrino Observatory has precisely determined the total active (nu(x)) 8B solar neutrino flux without assumptions about the energy dependence of the nu(e) survival probability. The measurements were made with dissolved NaCl in heavy water to enhance the sensitivity and signature for neutral-current interactions. The flux is found to be 5.

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Data from the Sudbury Neutrino Observatory have been used to constrain the lifetime for nucleon decay to "invisible" modes, such as n-->3nu. The analysis was based on a search for gamma rays from the deexcitation of the residual nucleus that would result from the disappearance of either a proton or neutron from 16O. A limit of tau(inv)>2 x 10(29) yr is obtained at 90% confidence for either neutron- or proton-decay modes.

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The Sudbury Neutrino Observatory (SNO) has measured day and night solar neutrino energy spectra and rates. For charged current events, assuming an undistorted 8B spectrum, the night minus day rate is 14.0%+/-6.

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Observations of neutral-current nu interactions on deuterium in the Sudbury Neutrino Observatory are reported. Using the neutral current (NC), elastic scattering, and charged current reactions and assuming the standard 8B shape, the nu(e) component of the 8B solar flux is phis(e) = 1.76(+0.

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Solar neutrinos from (8)B decay have been detected at the Sudbury Neutrino Observatory via the charged current (CC) reaction on deuterium and the elastic scattering (ES) of electrons. The flux of nu(e)'s is measured by the CC reaction rate to be straight phi(CC)(nu(e)) = 1.75 +/- 0.

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Tinnitus is a debilitating condition from which some 0.5-1% of the population of the Western world suffer sufficiently badly as to interfere with their normal working and leisure life. There is no satisfactory treatment at the present time and the uncertainty surrounding the mechanism of its generation makes it difficult to devise an effective cure.

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Objective: Tinnitus is an extremely prevalent condition that currently has no satisfactory clinical treatment. Development of therapy has been hampered by the diversity of underlying conditions that give rise to the symptom of tinnitus. A drug that has multiple actions may have an improved chance of being effective.

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We have carried out a comprehensive ESR and U-series dating study on the Lake Mungo 3 (LM3) human skeleton. The isotopic Th/U and Pa/U ratios indicate that some minor uranium mobilization may have occurred in the past. Taking such effects into account, the best age estimate for the human skeleton is obtained through the combination of U-series and ESR analyses yielding 62,000+/-6000 years.

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The Neanderthal hominid Tabun C1, found in Israel by Garrod & Bate, was attributed to either layer B or C of their stratigraphic sequence. We have used gamma-ray spectrometry to determine the 230Th/234U and 231Pa/235U ratios of two bones from this skeleton, the mandible and a femur. The ages calculated from these ratios depend on the uranium uptake history of the bones.

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Tinnitus is a prevalent condition which has no practical and effective pharmacological treatment. In the absence of relief by conventional routes, sufferers are increasingly turning to 'alternative' or 'complementary' medicine. This paper reports the evaluation of a homeopathic preparation 'Tinnitus' by a double-blind, placebo-controlled clinical trial.

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