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Search Results: 1 - 10 of 338734 matches for " C. K. Young "
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Studies of the Virgo cluster based on the Virgo Photometry Catalogue
C. K. Young
Physics , 1997,
Abstract: The `Virgo Photometry Catalogue' (VPC) is the first independently calibrated general catalogue of galaxies to cover the Virgo cluster since the `Catalog of Galaxies and Clusters of Galaxies' of Zwicky et al. (1961,1963). It contains 1180 galaxies (including background objects) within a 23 square-degree region centred on the cluster's core. Photographic surface photometry is presented for 1067 galaxies in the U band, for 1020 galaxies in the B_J band and for 1020 galaxies in the R_C band. All total magnitudes and total colours are extrapolated according to a new system; denoted `t' to distinguish it from the `T' system already in use. This paper outlines: the scope of the VPC, the new extrapolation system, some recent findings based on the catalogue and further work in progress.
Distance indicators based on the luminosity-profile shapes of early-type galaxies--a reply
C. K. Young,M. J. Currie,.
Physics , 1997,
Abstract: In a recent paper, Binggeli & Jerjen (1998) question the value of the extra- galactic distance indicators presented by Young & Currie (1994 & 1995) and state that they have refuted `the claim that the Virgo dEs [dwarf-elliptical galaxies]...are distributed in a prolate structure stretching from 8 to 20 Mpc distance (Young & Currie 1995).' even though no such claim was ever made. In this paper, we examine Binggeli & Jerjen's claims that intrinsic scatter rather than spatial depth must be the main cause of the large scatters observed in the relevant scaling relationships for Virgo galaxies. We investigate the accuracy of Binggeli & Jerjen's photometric parameters and find that while their profile curvature and scalelength measurements are probably useful, their total magnitude and central surface-brightness measurements are not useful for the purpose of investigating scaling laws because they suffer from serious systematic and random errors. We also investigate Binggeli & Jerjen's criti- cisms of our (1995) analysis. We demonstrate that their test for strong mutual dependence between distance estimates based on the two different scaling laws is invalid because of its prior assumption of negligible cluster depth. We further demonstrate that the [relative] distance estimates on which their kinematical arguments are based cannot be meaningful, not only because of the seriousness of the photometric errors, but also because they are undermined by the prior assumption that depth effects can again be neglected.
Development of a Portable Electronic Sensor for Detection of the Kudzu Bug, Megacopta cribraria (Fabricius) (Hemiptera: Plataspidae)  [PDF]
Brittany D. Lampson, David C. Degenhardt, Jeremy K. Greene, Ahmad Khalilian, Young J. Han
Advances in Entomology (AE) , 2017, DOI: 10.4236/ae.2017.53007
Abstract: The kudzu bug, Megacopta cribraria (Fabricius), recently became an invasive insect pest of soybean, Glycine max (L.) Merr. in the southeastern USA capable of reducing crop yield by as much as 60% if left untreated. To reduce these losses and minimize control costs, new methods for detecting kudzu bugs must be investigated in order to optimize control measures. One such method would be to detect volatiles released by kudzu bugs. An electronic portable device was developed to draw volatile organic compounds (VOCs) produced by kudzu bugs over carbon black-polymer composite sensors and measure the change in resistance for each sensor. Sensors made using polymers poly (bisphenol A carbonate) (p = 0.041), poly (styrene-co-allyl alcohol) (p = 0.017) and poly (vinylpyrrolidone) (p = 0.040) showed significant differences in resistance change for M. cribraria VOCs over the control. A logistic regression was 94.4% accurate based on the resistance changes from sensors made from polymers poly (4-vinylphenol), poly (styrene-co-allyl alcohol), and poly (vinylpyrrolidone) as features. These results indicate the capability of the device to detect kudzu bugs by detecting volatiles released by the insects.
Optimal quantum multi-parameter estimation and application to dipole- and exchange-coupled qubits
Kevin C. Young,Mohan Sarovar,Robert Kosut,K. Birgitta Whaley
Physics , 2008, DOI: 10.1103/PhysRevA.79.062301
Abstract: We consider the problem of quantum multi-parameter estimation with experimental constraints and formulate the solution in terms of a convex optimization. Specifically, we outline an efficient method to identify the optimal strategy for estimating multiple unknown parameters of a quantum process and apply this method to a realistic example. The example is two electron spin qubits coupled through the dipole and exchange interactions with unknown coupling parameters -- explicitly, the position vector relating the two qubits and the magnitude of the exchange interaction are unknown. This coupling Hamiltonian generates a unitary evolution which, when combined with arbitrary single-qubit operations, produces a universal set of quantum gates. However, the unknown parameters must be known precisely to generate high-fidelity gates. We use the Cram\'er-Rao bound on the variance of a point estimator to construct the optimal series of experiments to estimate these free parameters, and present a complete analysis of the optimal experimental configuration. Our method of transforming the constrained optimal parameter estimation problem into a convex optimization is powerful and widely applicable to other systems.
Right-handed Neutral Currents, Families and the LEP $l^+l^-γγ$ Events
C. Q. Geng,K. Whisnant,B. -L. Young
Physics , 1993,
Abstract: We explore the possibility of having new physics which could account for the $l^+l^-\gamma\gamma$ events with $M_{\gamma\gamma}\simeq 60\ $GeV recently reported by LEP. We consider models which contain an extra neutral gauge boson ($Z'$) that couples only to right-handed fermions. The models naturally require at least three quark and lepton families from anomaly cancellation. We find simple realizations of such models that have $\ell^+\ell^-\gamma\gamma$ events at a rate similar to that observed at LEP.
Fighting dephasing noise with robust optimal control
Kevin C. Young,Dylan J Gorman,K. Birgitta Whaley
Physics , 2010,
Abstract: We address the experimentally relevant problem of robust mitigation of dephasing noise acting on a qubit. We first present an extension of a method for representing $1/\omega^{\alpha}$ noise developed by Kuopanportti et al. to the efficient representation of arbitrary Markovian noise. We then add qubit control pulses to enable the design of numerically optimized, two-dimensional control functions with bounded amplitude, that are capable of decoupling the qubit from the dephasing effects of a broad variety of Markovian noise spectral densities during arbitrary one qubit quantum operations. We illustrate the method with development of numerically optimized control pulse sequences that minimize decoherence due to a combination of $1/\omega$ and constant offset noise sources. Comparison with the performance of standard dynamical decoupling protocols shows that the numerically optimized pulse sequences are considerably more robust with respect to the noise offset, rendering them attractive for application to situations where homogeneous dephasing noise sources are accompanied by some extent of heterogeneous dephasing. Application to the mitigation of dephasing noise on spin qubits in silicon indicates that high fidelity single qubit gates are possible with current pulse generation technology.
Quantum non-demolition measurements of single donor spins in semiconductors
Mohan Sarovar,Kevin C. Young,Thomas Schenkel,K. Birgitta Whaley
Physics , 2007, DOI: 10.1103/PhysRevB.78.245302
Abstract: We propose a technique for measuring the state of a single donor electron spin using a field-effect transistor induced two-dimensional electron gas and electrically detected magnetic resonance techniques. The scheme is facilitated by hyperfine coupling to the donor nucleus. We analyze the potential sensitivity and outline experimental requirements. Our measurement provides a single-shot, projective, and quantum non-demolition measurement of an electron-encoded qubit state.
Hamiltonian and Linear-Space Structure for Damped Oscillators: I. General Theory
S. C. Chee,Alec Maassen van den Brink,K. Young
Physics , 2002, DOI: 10.1088/0305-4470/37/37/008
Abstract: The phase space of $N$ damped linear oscillators is endowed with a bilinear map under which the evolution operator is symmetric. This analog of self-adjointness allows properties familiar from conservative systems to be recovered, e.g., eigenvectors are "orthogonal" under the bilinear map and obey sum rules, initial-value problems are readily solved and perturbation theory applies to the_complex_ eigenvalues. These concepts are conveniently represented in a biorthogonal basis.
Hamiltonian and Linear-Space Structure for Damped Oscillators: II. Critical Points
S. C. Chee,Alec Maassen van den Brink,K. Young
Physics , 2002, DOI: 10.1088/0305-4470/37/37/009
Abstract: The eigenvector expansion developed in the preceding paper for a system of damped linear oscillators is extended to critical points, where eigenvectors merge and the time-evolution operator $H$ assumes a Jordan-block structure. The representation of the bilinear map is obtained in this basis. Perturbations $\epsilon\Delta H$ around an $M$-th order critical point generically lead to eigenvalue shifts $\sim\epsilon^{1/M}$ dependent on only_one_ matrix element, with the $M$ eigenvalues splitting in equiangular directions in the complex plane. Small denominators near criticality are shown to cancel.
Raman Spectra of Triplet Superconductor in Sr$_2$RuO$_4$
Hae-Young Kee,K. Maki,C. H. Chung
Physics , 2002, DOI: 10.1103/PhysRevB.67.180504
Abstract: We study the Raman spectra of spin-triplet superconductors in Sr$_2$RuO$_4$. The p-wave and f-wave symmetries are considered. We show that there is the clapping mode with frequency of $\sqrt{2} \Delta(T)$ and $1.02 \Delta(T)$ for p-wave and f-wave superconductors, respectively. This mode is visible as a huge resonance in the B1g and B2g modes of Raman spectra. We discuss the details of the Raman spectra in these superconducting states.
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