The greater utilization of soft contact lenses calls for the development of new and objective methods of evaluating the optical performance of the different lens types, in situ. We used ...videokeratography to examine the surface topography of soft contact lenses that had been worn for more than 1 year on 27 eyes of 23 patients, and compared the resulting color-coded maps and topographic indices as well as contact lens-corrected visual acuities, with those obtained with new replacement lenses on the same eyes. Visual inspection of the color-coded maps revealed differences in the surface characteristics of the used and new lenses. Comparison of quantitative indices including the SAI (Surface Asymmetry Index), IAI (Irregular Astigmatism Index), SRI (Surface Regularity Index), and SDP (Standard Deviation of Powers) showed that asymmetry, surface irregularity, potential visual acuity (derived from the SRI), and corneal power distribution were significantly poorer with the used lenses than with the new (P = 0.0001). The videokeratoscope is useful for evaluating the soft contact lens surface in situ, as an indicator of optical quality; it also permits the objective evaluation of lens cleaning techniques.
Double beta decay of 100Mo to the excited states of daughter nuclei has been studied using a 600 cm3 low-background HPGe detector and an external source consisting of 2588 g of 97.5% enriched ...metallic 100Mo, which was formerly inside the NEMO-3 detector and used for the NEMO-3 measurements of 100Mo. The half-life for the two-neutrino double beta decay of 100Mo to the excited 01+ state in 100Ru is measured to be T1/2=7.5±0.6(stat)±0.6(syst)⋅1020 yr. For other (0ν+2ν) transitions to the 21+, 22+, 02+, 23+ and 03+ levels in 100Ru, limits are obtained at the level of ∼(0.25–1.1)⋅1022 yr.
The detection of keratoconus patterns on videokeratography is important for screening candidates for refractive surgery and for studying the genetic basis of keratoconus.
We compared three ...quantitative approaches to identifying keratoconus from videokeratographic information to examine the limitations and capabilities of each test and to determine their suitability for use in the clinical setting.
Videokeratographs typical of clinically diagnosed keratoconus (n = 44) and of various non-keratoconus conditions (n = 132, including normal, with-the-rule astigmatism, contact lens-induced corneal warpage, photorefractive keratectomy, keratoplasty, and pellucid marginal degeneration) were selected. Three methods for detecting keratoconus were used: keratometry (average Simulated Keratometry SimK readings > 45.7 diopters D); the modified Rabinowitz-McDonnell test (central corneal power > 47.2 D and/or Inferosuperior Asymmetry I-S value > 1.4 D); and an expert system classifier (classification based on discriminant analysis and classification tree with eight topographic indexes). Sensitivity and specificity were calculated for each test.
Sensitivities were 84% for keratometry, 96% for the modified Rabinowitz-McDonnell test, and 98% for the expert system classifier. Specificities for the three methods were 86%, 85%, and 99%, respectively. In terms of sensitivity, the expert system classifier was significantly better than keratometry (P = .04). In terms of specificity, the expert system classifier was significantly better than either of the other methods (P = .001).
For screening candidates for refractive surgery, where high sensitivity is needed, either the modified Rabinowitz-McDonnell test or the expert system classifier is suitable. For diagnosing keratoconus, where high specificity is more useful, the expert system classifier is more appropriate than the other two methods.
Stringent tests on top quark production and decay mechanisms are provided by the measurement of the top quark and W boson polarization. This paper presents a detailed study of these two measurements ...with the ATLAS detector, in the semileptonic (\(t\overline{t} \rightarrow W W b \overline{b}\rightarrow l \nu j_1 j_2 b \overline{b}\)) and dileptonic (\(t\overline{t} \rightarrow W W b \overline{b}\rightarrow l \nu l \nu b \overline{b}\)) \(t\bar{t}\) channels. It is based on leading-order Monte Carlo generators and on a fast simulation of the detector. A particular attention is paid to the systematic uncertainties, which dominate the statistical errors after one LHC year at low luminosity (10 fb-1), and to the background estimate. Combining results from both channel studies, the longitudinal component of the W polarization (F0) can be measured with a 2% accuracy and the right-handed component (FR, which is zero in the Standard Model) with a 1\(\%\) precision with 10 fb-1. Even though the top quarks in \(t\bar{t}\) pairs are not polarized, a large asymmetry is expected within the Standard Model in the like-spin versus unlike-spin pair production. A 4% precision on this asymmetry measurement is possible with 10 fb-1, after combining results from both channel studies. These promising results are converted in a sensitivity to new physics, such as tWb anomalous couplings, top decay to charged Higgs boson, or new s-channels (heavy resonance, gravitons) in \(t\bar{t}\) production.
We examine the top quark production in the brane world scenario. We study two typical models - the model proposed by Arkani-Hamed, Dimopoulos and Dvali (ADD) and the model of Randall and Sundrum ...(RS). In addition to the Standard Model processes, there is a new contribution to the top-antitop pair production process mediated by graviton Kaluza-Klein modes in the s-channel. We calculated the density matrix for the top-antitop pair production including the new contribution. With a reasonable parameter choice, we find a sizable deviation of the top-antitop quark spin correlations from those in the Standard Model.
We report the results of a first experimental search for lepton number violation by four units in the neutrinoless quadruple-β decay of ^{150}Nd using a total exposure of 0.19 kg yr recorded with the ...NEMO-3 detector at the Modane Underground Laboratory. We find no evidence of this decay and set lower limits on the half-life in the range T_{1/2}>(1.1-3.2)×10^{21} yr at the 90% C.L., depending on the model used for the kinematic distributions of the emitted electrons.
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