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1

UNBIASED MOMENT-RATE SPECTRA AND ABSOLUTE SITE EFFECTS IN THE KACHCHH BASIN, INDIA, FROM THE ANALYSIS OF THE AFTERSHOCKS OF THE 2001 Mw 7.6 BHUJ EARTHQUAKE  

SciTech Connect

What can be learned about absolute site effects on ground motions and about earthquake source spectra from recordings at temporary seismic stations, none of which could be considered a 'reference' (hard rock) site, for which no geotechnical information is available, in a very poorly instrumented region? This challenge motivated our current study of aftershocks of the 2001 Mw 7.6 Bhuj earthquake, in Western India. Crustal attenuation and spreading relationships based on the same data used here were determined in an earlier study. In this paper we decouple the ambiguity between absolute source radiation and site effects by first computing robust estimates of moment-rate spectra of about 200 aftershocks in each of two depth ranges. Using these new estimates of sourcespectra, and our understanding of regional wave propagation, we extract the absolute site terms of the sites of the temporary deployment. Absolute site terms (one for each component of the ground motion, for each station) are computed in an average sense, via an L{sub 1}-norm minimization, and results for each site are averaged over wide ranges of azimuths and takeoff angles. The Bhuj deployment is characterized by a variable shallow geology, mostly of soft sedimentary units. Vertical site terms in the region were observed to be almost featureless and slightly < 1.0 within wide frequency ranges. As a result, H/V spectral ratios mimic the absolute behaviors of absolute horizontal site terms, and they generally overpredict them. On the contrary, with respect to the results for sedimentary rock sites (limestone, dolomite) obtained by Malagnini et al. (2004), H/V spectral ratios in their study did not have much in common with absolute horizontal site terms. Spectral ratios between the vector sum of the computed horizontal site terms for the temporary deployment with respect to the same quantity computed at the hardest rock station available, BAC1, are seriously biased by its non-flat, non-unitary site response. This indicates that often the actual behavior of a rock outcrop is far from that of an ideal, reference site.

Malagnini, L; Bodin, P; Mayeda, K; Akinci, A

2005-05-04

2

Chasing unbiased spectra of the Universe  

NASA Astrophysics Data System (ADS)

The cosmological power spectrum of the coherent matter flow is measured exploiting an improved prescription for the apparent anisotropic clustering pattern in redshift space. New statistical analysis is presented to provide an optimal observational platform to link the improved redshift distortion theoretical model to future real data sets. The statistical power as well as robustness of our method are tested against 60 realizations of 8h-3Gpc3 dark matter simulation maps mocking the precision level of upcoming wide-deep surveys. We showed that we can accurately extract the velocity power spectrum up to quasilinear scales of k˜0.1hMpc-1 at z=0.35 and up to k˜0.15hMpc-1 at higher redshifts within a couple of percentage precision levels. Our understanding of redshift space distortion is proved to be appropriate for precision cosmology, and our statistical method will guide us to a righteous path to meet the real world.

Song, Yong-Seon; Nishimichi, Takahiro; Taruya, Atsushi; Kayo, Issha

2013-06-01

3

The Mutually Unbiased Bases Revisited  

Microsoft Academic Search

The study of Mutually Unbiased Bases continues to be developed vigorously, and presents several challenges in the Quantum Information Theory. Two orthonormal bases in $\\\\mathbb C^d, B {and} B'$ are said mutually unbiased if $\\\\forall b\\\\in B, b'\\\\in B'$ the scalar product $b\\\\cdot b'$ has modulus $d^{-1\\/2}$. In particular this property has been introduced in order to allow an optimization

Monique Combescure; Batiment Paul Dirac

2006-01-01

4

On the comparisons of seismic moment rates determined from historic earthquakes, GPS and Quaternary fault slip rates  

NASA Astrophysics Data System (ADS)

The long-term horizontal strain rate field in the India-Eurasia plate boundary zone is determined from Quaternary fault slip rates and recent GPS data. Strain rates estimated from recent GPS data in Southeastern and Northeastern China are less than 1x10-9 /yr, insignificantly different from zero, which is consistent with the rigid block or plate assumptions in recent tectonic models. We estimate the tectonic moment rates in various seismic zones in China and surrounding regions using the horizontal strain rates from the joint-inversion of geological and GPS data. The total earthquake moment rate inferred from historic earthquakes over different time periods is about 70-80 % of the total tectonic moment rate within the seismogenic volume. They are consistent with each other within one sigma confidence level. However the moment rates inferred from historic seismicity in the seismic zones containing the Kunlun fault, the Altyn Tagh fault, and Yushu-Mani fault zone in northern Tibet, the eastern Tian Shan, and Shanxi Graben system are significantly smaller than the tectonic moment rates. Our preliminary results also indicate that the extension rates across the Shanxi graben, the Weihe Basin, and Hetao basin are no more than 2 mm/yr. Nor do the left-lateral or right-lateral slip rates across these active graben systems exceed 2 mm/yr. The total horizontal slip rates across these graben structures seem to be lower than the slip rate estimates from previous studies. The discrepancies between the long-term moment rates and moment rates inferred from seismicity or geological information could have significant implications in seismic hazard calculations in China. Although the uncertainties in the current GPS data are still too large to confidently reject or modify any previous results, the addition of GPS data will no doubt help to improve uncertainties or reduce biases in seismic hazard models that are based either on historic seismicity alone or seismicity data combined with geological data.

Shen-Tu, B.; Mahdyiar, M.; Rong, Y.

2004-12-01

5

Seismic moment rate and earthquake mean recurrence interval in the major tectonic boundaries around Oman  

NASA Astrophysics Data System (ADS)

Owing to the short earthquake history, mathematical relationships were developed for calculating the earthquake recurrence from the rate of slip along the active faults. Based on the slip rate and the well-known Gutenberg-Richter law, various relationships between the earthquake occurrence parameters and the crustal deformation rates were developed. Among those is the widely used Molnar (1979 Bull. Seismol. Soc. Am. 69 115-33) mathematical expression, which is modified in the current study to produce a mathematical model based upon the truncated Gutenberg-Richter model instead of the normal Gutenberg-Richter one. The modified model is then tested and applied for the major tectonic boundaries around the Sultanate of Oman. The seismic moment rate is determined and the seismic hazard in terms of recurrence interval is expressed for the investigated regions. The calculated recurrence interval with moment magnitude 8.1 in the Makran zone is found to be 760 years, while for earthquakes with magnitude equal or greater than 5.8 in the Owen fracture zone is 4.904 years in consistency with the observed data. Recurrence intervals resulting from the original Molnar (1979) model and the current modified model were compared and discussed for the Zagros region.

Deif, A.; El-Hussain, I.

2012-12-01

6

Optimal unbiased filtering via linear matrix inequalities  

Microsoft Academic Search

Solutions to the optimal H? and L2?L? unbiased reduced-order filtering problems are obtained in terms of linear matrix inequalities (LMIs). The order of the optimal filter is equal to the number of measurements. Both continuous- and discrete-time results are presented. An explicit parametrization of all optimal unbiased filters is provided in terms of a free contractive matrix.

Karolos M. Grigoriadis

1998-01-01

7

Unbiased Sequential Estimation for Binomial Populations  

Microsoft Academic Search

The subject of minimum variance unbiased estimation has received a great deal of attention in the statistical literature, e.g., in the papers of Bahadur [2], Barankin [3], and Stein [14]. The emphasis in these papers has typically been placed on the existence and construction of minimum variance unbiased estimators when the sampling plan to be used was given in advance.

Morris H. DeGroot

1959-01-01

8

A SPITZER UNBIASED ULTRADEEP SPECTROSCOPIC SURVEY  

SciTech Connect

We carried out an unbiased, spectroscopic survey using the low-resolution module of the infrared spectrograph (IRS) onboard Spitzer targeting two 2.6 square arcminute regions in the GOODS-North field. The IRS was used in a spectral mapping mode with 5 hr of effective integration time per pixel. One region was covered between 14 and 21 mum and the other between 20 and 35 mum. We extracted spectra for 45 sources. About 84% of the sources have reported detections by GOODS at 24 mum, with a median f {sub n}u(24 mum) approx 100 muJy. All but one source are detected in all four IRAC bands, 3.6 to 8 mum. We use a new cross-correlation technique to measure redshifts and estimate IRS spectral types; this was successful for approx60% of the spectra. Fourteen sources show significant polycyclic aromatic hydrocarbon emission, four mostly SiO absorption, eight present mixed spectral signatures (low PAH and/or SiO) and two show a single line in emission. For the remaining 17, no spectral features were detected. Redshifts range from z approx 0.2 to z approx 2.2, with a median of 1. IR luminosities are roughly estimated from 24 mum flux densities, and have median values of 2.2 x 10{sup 11} L{sub sun} and 7.5 x 10{sup 11} L{sub sun} at z approx 1 and z approx 2, respectively. This sample has fewer active galactic nuclei than previous faint samples observed with the IRS, which we attribute to the fainter luminosities reached here.

Bertincourt, B.; Lagache, G.; Puget, J-L. [Institut d'Astrophysique Spatiale (IAS), Universite Paris-Sud 11 and CNRS (UMR 8617), Batiment 121, F-91405 Orsay (France); Helou, G.; Appleton, P.; Ogle, P.; Brooke, T.; Sheth, K. [Spitzer Science Center, Infrared Processing and Analysis Center, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Smith, J-D. [Steward Observatory, University of Arizona, Tucson, AZ (United States); Dale, D. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Harwit, M. [511 H Street, SW, Washington DC 20024-2725 (United States)] [Cornell University, Ithaca, NY (United States); Roussel, H., E-mail: benjamin.bertincourt@ias.u-psud.f, E-mail: guilaine.lagache@ias.u-psud.f, E-mail: jean-loup.puget@ias.u-psud.f [Institut d'Astrophysique de Paris, UPMC (Universite Paris 6), 75014 Paris (France)

2009-11-01

9

[Unbiased criteria for estimation of the transition from unordered to ordered motor activity of the olfactory cilia].  

PubMed

Unbiased criteria (Lissajous figures, entropy, and harmonic spectra) have been developed to estimate the transition from an unordered to an ordered motor activity of olfactory cilia, which occurs by the action of odorants on flagellata. PMID:21033357

Bigda?, E V; Samo?lov, V O; Bekusova, V V; Kryzhanovski?, V E; Dudich, B A; Panov, V A

10

Best linear unbiased design hyetograph  

NASA Astrophysics Data System (ADS)

Under the conditions of system linearity and stationarity of the precipitation process we derive the hyetograph associated with any given flood discharge Q, using best linear unbiased estimation (BLUE) theory. The BLUE hyetograph depends explicitly on the correlation characteristics of the rainfall process and the instantaneous unit hydrograph (IUH) of the basin. When the correlation time of the rainfall process is short relative to the dispersion of the IUH, the shape of the BLUE hyetograph is the mirror image of the IUH itself. In the opposite case the design hyetograph is the mirror image of the rainfall correlation function. The procedure is extended from lumped to semidistributed and distributed basins. In the latter case we obtain simultaneous design hyetographs for each subbasin or each site in the basin. The analytical findings and the possibility of regionalization are verified using synthetic and recorded rainfall time series, with excellent agreement in both cases. Because of its simplicity, robustness, and theoretical basis the proposed procedure should be appealing for practical use, particularly when not only the peak but the entire flood hydrograph is required.

Veneziano, Daniele; Villani, Paolo

1999-09-01

11

Current injection in unbiased asymmetrical quantum wells  

Microsoft Academic Search

Summary form only given. Coherently controlled photocurrents have recently been observed in quantum wells (QW) and bulk semiconductors. In these experiments, optical injection of currents in unbiased samples is achieved by an asymmetry in the light field produced through the interference of two beams

R. D. R. Bhat; J. E. Sipe

1999-01-01

12

On unbiased games on random graphs  

Microsoft Academic Search

We study unbiased Maker-Breaker positional games played on the edges of the random graph G(n;p). As the main result of the paper, we prove a conjecture from (18), that the property that Maker is able to win the Hamiltonicity game played on a random graph G(n;p) has a sharp threshold at log n n . Our theorem can be considered

Dan Hefetz; Michael Krivelevich; Milos Stojakovic; Tibor Szabo

2007-01-01

13

Nearly unbiased variable selection under minimax concave penalty  

Microsoft Academic Search

We propose MC+, a fast, continuous, nearly unbiased and accurate method of penalized variable selection in high-dimensional linear regression. The LASSO is fast and continuous, but biased. The bias of the LASSO may prevent consistent variable selection. Subset selection is unbiased but computationally costly. The MC+ has two elements: a minimax concave penalty (MCP) and a penalized linear unbiased selection

Cun-Hui Zhang

2010-01-01

14

Fault depth and seismic moment rate estimates of the San Andreas Fault System: Observations from seismology and geodesy  

NASA Astrophysics Data System (ADS)

The depth of the seismogenic zone is a critical parameter for earthquake hazard models of the San Andreas Fault System. Independent observations from both seismology and geodesy can provide insight into the depths of faulting, however these depths do not always agree. Here we inspect variations in fault depths of 12 segments of the southern San Andreas Fault System derived from over 1000 GPS velocities and 66,000 relocated earthquake hypocenters. Geodetically-determined locking depths range from 6-22 km, while seismogenic thicknesses are largely limited to depths of 11-20 km. Seismogenic depths best match the geodetic locking depths when estimated at the 95% cutoff depth in seismicity and most fault segment depths agree to within 2 km. However, we identify 3 outliers (Imperial, Coyote Creek, and Borrego segments) with significant discrepancies. In these cases the geodetically-inferred locking depths are much shallower than the seismogenic depths. We also inspect seismic moment accumulation rates per unit fault length, with the highest rates estimated for the Mojave and Carrizo segments (~1.8 x 1013 Nm/yr/km) and the lowest rates (~0.2 x 1013 Nm/yr/km) found along several San Jacinto segments. The largest variation in seismic moment is calculated for the Imperial segment, where the moment rate from seismic depths is nearly a factor of 2.5 larger than that from geodetic depths. Such variability has important implications for the accuracy to which the magnitude of future major earthquakes can be estimated.

Smith-Konter, B. R.; Sandwell, D. T.; Shearer, P. M.

2010-12-01

15

Arithmetic, mutually unbiased bases and complementary observables  

SciTech Connect

Complementary observables in quantum mechanics may be viewed as Frobenius structures in a dagger monoidal category, such as the category of finite dimensional Hilbert spaces over the complex numbers. On the other hand, their properties crucially depend on the discrete Fourier transform and its associated quantum torus, requiring only the finite fields that underlie mutually unbiased bases. In axiomatic topos theory, the complex numbers are difficult to describe and should not be invoked unnecessarily. This paper surveys some fundamentals of quantum arithmetic using finite field complementary observables, with a view considering more general axiom systems.

Sheppeard, M. D. [Oxford University Computing Laboratory, Wolfson Building, Parks Rd., Oxford OX1 3QD (United Kingdom)

2010-02-15

16

Unbiased diffusion in tubes with corrugated walls  

NASA Astrophysics Data System (ADS)

This study is devoted to unbiased motion of a point Brownian particle in a tube with corrugated walls made of conical sections of a varying length. Effective one-dimensional description in terms of the generalized Fick-Jacobs equation is used to derive a formula which gives the effective diffusion coefficient of the particle as a function of the geometric parameters of the tube. Comparison with the results of Brownian dynamics simulations allows us to establish the domain of applicability of both the one-dimensional description and the formula for the effective diffusion coefficient.

Dagdug, Leonardo; Vazquez, Marco-Vinicio; Berezhkovskii, Alexander M.; Bezrukov, Sergey M.

2010-07-01

17

Markovian description of unbiased polymer translocation  

NASA Astrophysics Data System (ADS)

We perform, with the help of cloud computing resources, extensive Langevin simulations which provide compelling evidence in favor of a general Markovian framework for unbiased three-dimensional polymer translocation. Our statistical analysis consists of careful evaluations of (i) two-point correlation functions of the translocation coordinate and (ii) the empirical probabilities of complete polymer translocation (taken as a function of the initial number of monomers on a given side of the membrane). We find good agreement with predictions derived from the Markov chain approach recently addressed in the literature by the present authors.

Mondaini, Felipe; Moriconi, L.

2012-10-01

18

Unbiased sampling of lattice Hamilton path ensembles.  

PubMed

Hamilton paths, or Hamiltonian paths, are walks on a lattice which visit each site exactly once. They have been proposed as models of globular proteins and of compact polymers. A previously published algorithm [Mansfield, Macromolecules 27, 5924 (1994)] for sampling Hamilton paths on simple square and simple cubic lattices is tested for bias and for efficiency. Because the algorithm is a Metropolis Monte Carlo technique obviously satisfying detailed balance, we need only demonstrate ergodicity to ensure unbiased sampling. Two different tests for ergodicity (exact enumeration on small lattices, nonexhaustive enumeration on larger lattices) demonstrate ergodicity unequivocally for small lattices and provide strong support for ergodicity on larger lattices. Two other sampling algorithms [Ramakrishnan et al., J. Chem. Phys. 103, 7592 (1995); Lua et al., Polymer 45, 717 (2004)] are both known to produce biases on both 2x2x2 and 3x3x3 lattices, but it is shown here that the current algorithm gives unbiased sampling on these same lattices. Successive Hamilton paths are strongly correlated, so that many iterations are required between statistically independent samples. Rules for estimating the number of iterations needed to dissipate these correlations are given. However, the iteration time is so fast that the efficiency is still very good except on extremely large lattices. For example, even on lattices of total size 10x10x10 we are able to generate tens of thousands of uncorrelated Hamilton paths per hour of CPU time. PMID:17059235

Mansfield, Marc L

2006-10-21

19

Unbiased sampling of lattice Hamilton path ensembles  

NASA Astrophysics Data System (ADS)

Hamilton paths, or Hamiltonian paths, are walks on a lattice which visit each site exactly once. They have been proposed as models of globular proteins and of compact polymers. A previously published algorithm [Mansfield, Macromolecules 27, 5924 (1994)] for sampling Hamilton paths on simple square and simple cubic lattices is tested for bias and for efficiency. Because the algorithm is a Metropolis Monte Carlo technique obviously satisfying detailed balance, we need only demonstrate ergodicity to ensure unbiased sampling. Two different tests for ergodicity (exact enumeration on small lattices, nonexhaustive enumeration on larger lattices) demonstrate ergodicity unequivocally for small lattices and provide strong support for ergodicity on larger lattices. Two other sampling algorithms [Ramakrishnan et al., J. Chem. Phys. 103, 7592 (1995); Lua et al., Polymer 45, 717 (2004)] are both known to produce biases on both 2×2×2 and 3×3×3 lattices, but it is shown here that the current algorithm gives unbiased sampling on these same lattices. Successive Hamilton paths are strongly correlated, so that many iterations are required between statistically independent samples. Rules for estimating the number of iterations needed to dissipate these correlations are given. However, the iteration time is so fast that the efficiency is still very good except on extremely large lattices. For example, even on lattices of total size 10×10×10 we are able to generate tens of thousands of uncorrelated Hamilton paths per hour of CPU time.

Mansfield, Marc L.

2006-10-01

20

FAST TRACK COMMUNICATION: Affine constellations without mutually unbiased counterparts  

NASA Astrophysics Data System (ADS)

It has been conjectured that a complete set of mutually unbiased bases in a space of dimension d exists if and only if there is an affine plane of order d. We introduce affine constellations and compare their existence properties with those of mutually unbiased constellations. The observed discrepancies make a deeper relation between the two existence problems unlikely.

Weigert, Stefan; Durt, Thomas

2010-10-01

21

O Biased and Unbiased Diffusion in Fractal Media  

Microsoft Academic Search

Using a renormalization method first introduced by Machta, we study the random motion of a walker on different fractal structures. We analyze the biased and unbiased motion of such walkers in the presence of an external field and also in an unbiased environment respectively. We concentrate on two types of fractal structures: looples structures and structures that consist entirely of

Hernan Leonardo Martinez

1993-01-01

22

Unbiased scores in proportional hazards regression with covariate measurement error  

Microsoft Academic Search

This paper studies estimation of regression parameters in proportional hazards regression when covariates are subject to additive measurement error. It is shown how to construct an unbiased partial likelihood score when the moment generating function of the measurement error exists. The score is unbiased over a restriction on the parameter space where the restriction depends on the domain of definition

Jeffrey S. Buzas

1998-01-01

23

Experimental studies of unbiased gluon jets from e+e- annihilations using the jet boost algorithm  

NASA Astrophysics Data System (ADS)

We present the first experimental results based on the jet boost algorithm, a technique to select unbiased samples of gluon jets in e+e- annihilations, i.e. gluon jets free of biases introduced by event selection or jet finding criteria. Our results are derived from hadronic Z0 decays observed with the OPAL detector at the LEP e+e- collider at CERN. First, we test the boost algorithm through studies with HERWIG Monte Carlo events and find that it provides accurate measurements of the charged particle multiplicity distributions of unbiased gluon jets for jet energies larger than about 5 GeV, and of the jet particle energy spectra (fragmentation functions) for jet energies larger than about 14 GeV. Second, we apply the boost algorithm to our data to derive unbiased measurements of the gluon jet multiplicity distribution for energies between about 5 and 18 GeV, and of the gluon jet fragmentation function at 14 and 18 GeV. In conjunction with our earlier results at 40 GeV, we then test QCD calculations for the energy evolution of the distributions, specifically the mean and first two nontrivial normalized factorial moments of the multiplicity distribution, and the fragmentation function. The theoretical results are found to be in global agreement with the data, although the factorial moments are not well described for jet energies below about 14 GeV.

Abbiendi, G.; Ainsley, C.; Åkesson, P. F.; Alexander, G.; Allison, J.; Amaral, P.; Anagnostou, G.; Anderson, K. J.; Arcelli, S.; Asai, S.; Axen, D.; Azuelos, G.; Bailey, I.; Barberio, E.; Barillari, T.; Barlow, R. J.; Batley, R. J.; Bechtle, P.; Behnke, T.; Bell, K. W.; Bell, P. J.; Bella, G.; Bellerive, A.; Benelli, G.; Bethke, S.; Biebel, O.; Boeriu, O.; Bock, P.; Boutemeur, M.; Braibant, S.; Brigliadori, L.; Brown, R. M.; Buesser, K.; Burckhart, H. J.; Campana, S.; Carnegie, R. K.; Caron, B.; Carter, A. A.; Carter, J. R.; Chang, C. Y.; Charlton, D. G.; Ciocca, C.; Csilling, A.; Cuffiani, M.; Dado, S.; de Roeck, A.; de Wolf, E. A.; Desch, K.; Dienes, B.; Donkers, M.; Dubbert, J.; Duchovni, E.; Duckeck, G.; Duerdoth, I. P.; Etzion, E.; Fabbri, F.; Feld, L.; Ferrari, P.; Fiedler, F.; Fleck, I.; Ford, M.; Frey, A.; Fürtjes, A.; Gagnon, P.; Gary, J. W.; Gaycken, G.; Geich-Gimbel, C.; Giacomelli, G.; Giacomelli, P.; Giunta, M.; Goldberg, J.; Gross, E.; Grunhaus, J.; Gruwé, M.; Günther, P. O.; Gupta, A.; Hajdu, C.; Hamann, M.; Hanson, G. G.; Harel, A.; Hauschild, M.; Hawkes, C. M.; Hawkings, R.; Hemingway, R. J.; Hensel, C.; Herten, G.; Heuer, R. D.; Hill, J. C.; Hoffman, K.; Horváth, D.; Igo-Kemenes, P.; Ishii, K.; Jeremie, H.; Jovanovic, P.; Junk, T. R.; Kanaya, N.; Kanzaki, J.; Karlen, D.; Kawagoe, K.; Kawamoto, T.; Keeler, R. K.; Kellogg, R. G.; Kennedy, B. W.; Klein, K.; Klier, A.; Kluth, S.; Kobayashi, T.; Kobel, M.; Komamiya, S.; Kormos, L.; Krämer, T.; Krieger, P.; von Krogh, J.; Kruger, K.; Kuhl, T.; Kupper, M.; Lafferty, G. D.; Landsman, H.; Lanske, D.; Layter, J. G.; Lellouch, D.; Letts, J.; Levinson, L.; Lillich, J.; Lloyd, S. L.; Loebinger, F. K.; Lu, J.; Ludwig, A.; Ludwig, J.; MacPherson, A.; Mader, W.; Marcellini, S.; Martin, A. J.; Masetti, G.; Mashimo, T.; Mättig, P.; McDonald, W. J.; McKenna, J.; McMahon, T. J.; McPherson, R. A.; Meijers, F.; Menges, W.; Merritt, F. S.; Mes, H.; Michelini, A.; Mihara, S.; Mikenberg, G.; Miller, D. J.; Moed, S.; Mohr, W.; Mori, T.; Mutter, A.; Nagai, K.; Nakamura, I.; Nanjo, H.; Neal, H. A.; Nisius, R.; O'Neale, S. W.; Oh, A.; Okpara, A.; Oreglia, M. J.; Orito, S.; Pahl, C.; Pásztor, G.; Pater, J. R.; Pilcher, J. E.; Pinfold, J.; Plane, D. E.; Poli, B.; Polok, J.; Pooth, O.; Przybycie?, M.; Quadt, A.; Rabbertz, K.; Rembser, C.; Renkel, P.; Roney, J. M.; Rosati, S.; Rozen, Y.; Runge, K.; Sachs, K.; Saeki, T.; Sarkisyan, E. K. G.; Schaile, A. D.; Schaile, O.; Scharff-Hansen, P.; Schieck, J.; Schörner-Sadenius, T.; Schröder, M.; Schumacher, M.; Schwick, C.; Scott, W. G.; Seuster, R.; Shears, T. G.; Shen, B. C.; Sherwood, P.; Skuja, A.; Smith, A. M.; Sobie, R.; Söldner-Rembold, S.; Spano, F.; Stahl, A.; Stephens, K.; Strom, D.; Ströhmer, R.; Tarem, S.; Tasevsky, M.; Teuscher, R.; Thomson, M. A.; Torrence, E.; Toya, D.; Tran, P.; Trigger, I.; Trócsányi, Z.; Tsur, E.; Turner-Watson, M. F.; Ueda, I.; Ujvári, B.; Vollmer, C. F.; Vannerem, P.; Vértesi, R.; Verzocchi, M.; Voss, H.; Vossebeld, J.; Waller, D.; Ward, C. P.; Ward, D. R.; Watkins, P. M.; Watson, A. T.; Watson, N. K.; Wells, P. S.; Wengler, T.; Wermes, N.; Wetterling, D.; Wilson, G. W.; Wilson, J. A.; Wolf, G.; Wyatt, T. R.; Yamashita, S.; Zer-Zion, D.; Zivkovic, L.

2004-02-01

24

Unbiased combinations of nonanalog Monte Carlo techniques and fair games  

SciTech Connect

Historically, Monte Carlo variance reduction techniques have been developed one at a time in response to calculational needs. This paper reports that the theoretical basis is provided for obtaining unbiased Monte Carlo estimates from all possible combinations of variance reduction techniques. Hitherto, the techniques have not been proven to be unbiased in arbitrary combinations. The authors are unaware of any Monte Carlo techniques (in any linear process) that are not treated by the theorem herein.

Booth, T.E.; Pederson, S.P. (Los Alamos National Lab., Los Alamos, NM (US))

1992-03-01

25

Maximally entangled states via mutual unbiased collective bases  

SciTech Connect

Relative and center-of-mass coordinates are used to generalize mutually unbiased bases (MUB) and define mutually unbiased collective bases (MUCB). Maximally entangled states are given as product states in the collective variables. These states are analyzed in terms of the Wigner representative function of the states and shown to display a discontinuous attribute of the entanglement. Finite Hilbert space dimensionality collective coordinates are introduced and provide a framework for the analysis.

Revzen, M. [Department of Physics, Technion--Israel Institute of Technology, Haifa 32000 (Israel)

2010-01-15

26

Quantum process reconstruction based on mutually unbiased basis  

NASA Astrophysics Data System (ADS)

We study a quantum process reconstruction based on the use of mutually unbiased projectors (MUB projectors) as input states for a D-dimensional quantum system, with D being a power of a prime number. This approach connects the results of quantum-state tomography using mutually unbiased bases with the coefficients of a quantum process, expanded in terms of MUB projectors. We also study the performance of the reconstruction scheme against random errors when measuring probabilities at the MUB projectors.

Fernández-Pérez, A.; Klimov, A. B.; Saavedra, C.

2011-05-01

27

Quantum process reconstruction based on mutually unbiased basis  

SciTech Connect

We study a quantum process reconstruction based on the use of mutually unbiased projectors (MUB projectors) as input states for a D-dimensional quantum system, with D being a power of a prime number. This approach connects the results of quantum-state tomography using mutually unbiased bases with the coefficients of a quantum process, expanded in terms of MUB projectors. We also study the performance of the reconstruction scheme against random errors when measuring probabilities at the MUB projectors.

Fernandez-Perez, A.; Saavedra, C. [Center for Optics and Photonics, Universidad de Concepcion, Casilla 4016, Concepcion (Chile); Departamento de Fisica, Facultad de Ciencias Fisicas y Matematicas, Universidad de Concepcion, Casilla 160-C, Concepcion (Chile); Klimov, A. B. [Center for Optics and Photonics, Universidad de Concepcion, Casilla 4016, Concepcion (Chile); Departamento de Fisica, Universidad de Guadalajara, Revolucion 1500, 44410 Guadalajara, Jalisco (Mexico)

2011-05-15

28

Unbiased Risk Estimates for Singular Value Thresholding and Spectral Estimators  

NASA Astrophysics Data System (ADS)

In an increasing number of applications, it is of interest to recover an approximately low-rank data matrix from noisy observations. This paper develops an unbiased risk estimate---holding in a Gaussian model---for any spectral estimator obeying some mild regularity assumptions. In particular, we give an unbiased risk estimate formula for singular value thresholding (SVT), a popular estimation strategy which applies a soft-thresholding rule to the singular values of the noisy observations. Among other things, our formulas offer a principled and automated way of selecting regularization parameters in a variety of problems. In particular, we demonstrate the utility of the unbiased risk estimation for SVT-based denoising of real clinical cardiac MRI series data. We also give new results concerning the differentiability of certain matrix-valued functions.

Candes, Emmanuel J.; Sing-Long, Carlos A.; Trzasko, Joshua D.

2013-10-01

29

Improved image watermarking using pixel averaging and unbiased retrieval  

Microsoft Academic Search

Digital watermarking based on pixels modification for color image is considered in this paper. Its operations are described and its performance is investigated. Based on our observations, a method based on pixel averaging and unbiased watermark retrieval is proposed in order to improve the efficiency of the considering watermarking method. Particularly, we first apply the pixel averaging technique to create

Thitiporn Pramoun; Thumrongrat Amornraksa

2009-01-01

30

New unbiased symmetric metrics for evaluation of air quality models  

Microsoft Academic Search

Unbiased symmetric metrics to quantify the relative bias and error between modeled and observed concentrations, based on the factor between measured and observed concentrations, are introduced and compared to conventionally employed metrics. Application to the evaluation of several data sets shows that the new metrics overcome concerns with the conventional metrics and provide useful measures of model performance.

Shaocai Yu; Brian Eder; Robin Dennis; Shao-Hang Chu; Stephen E. Schwartz

2006-01-01

31

Best Linear Unbiased Prediction in the Generalized Linear Regression Model  

Microsoft Academic Search

When interdependence of disturbances is present in a regression model, the pattern of sample residuals contains information which is useful in prediction of post-sample drawings. This information, which is often overlooked, is exploited in the best linear unbiased predictor derived here. The gain in efficiency associated with using this predictor instead of the usual expected value estimator may be substantial.

Arthur S. Goldberger

1962-01-01

32

Unbiased Categorical Classification of Pediatric Sleep Disordered Breathing  

PubMed Central

Study Objectives: To classify pediatric sleep disordered breathing (SDB) using unbiased approaches. In children, decisions regarding severity and treatment of SDB are conducted solely based on empirical observations. Although recognizable entities clearly exist under the SDB spectrum, neither the number of SDB categories nor their specific criteria have been critically defined. Design: retrospective cohort analysis and random prospective cohort Setting: community and clinical sample Patients or Participants: Urban 5- to 9-year-old community children undergoing overnight sleep study (NPSG), and a comparable prospectively recruited clinical SDB sample. Interventions: n/a Measurements and Results: Principal component analysis was used to identify the uniqueness of the polysomnographically derived measures that are routinely used in clinical settings: apnea-hypopnea index, apnea index, obstructive apnea index, nadir SpO2, spontaneous arousal index and respiratory arousal index. These measures were then incorporated using unbiased data mining approaches to further characterize and discriminate across categorical phenotypes. Of 1,133 subjects, 52.8% were habitual snorers. Six categorical phenotypes clustered without any a priori hypothesis. Secondly, a non-hierarchical model that incorporated 6 NPSG-derived measures enabled unbiased identification of algorithms that predicted these 6 severity-based clusters. Thirdly, a hierarchical model was developed and performed well on all severity-based clusters. Classification and predictive models were subsequently cross-validated statistically as well as clinically, using 2 additional datasets that included 259 subjects. Modeling reached ?93% accuracy in cluster assignment. Conclusions: Data-driven analysis of conventional NPSG-derived indices identified 6 distinct clusters ranging from a cluster with normal indices toward clusters with more abnormal indices. Categorical assignment of individual cases to any of such clusters can be accurately predicted using a simple algorithm. These clusters may further enable prospective unbiased characterization of clinical outcomes and of genotype-phenotype interactions across multiple datasets. Citation: Spruyt K; Verleye G; Gozal D. Unbiased categorical classification of pediatric sleep disordered breathing. SLEEP 2010;33(10):1341-1347.

Spruyt, Karen; Verleye, Gino; Gozal, David

2010-01-01

33

Nearly Best Linear Unbiased Estimation of the Mean and Standard Deviation of the Logistic Distribution.  

National Technical Information Service (NTIS)

The method of nearly best linear unbiased estimation, which was developed through order statistics, for obtaining unbiased estimators for use in estimating the location and scale parameters of continuous distribution is applied to the logistic distributio...

J. W. Rodgers

1968-01-01

34

New Construction of Mutually Unbiased Bases in Square Dimensions  

Microsoft Academic Search

We show that k=w+2 mutually unbiased bases can be constructed in any square dimension d=s^2 provided that there are w mutually orthogonal Latin squares of order s. The construction combines the design-theoretic objects (k,s)-nets (which can be constructed from w mutually orthogonal Latin squares of order s and vice versa) and generalized Hadamard matrices of size s. Using known lower

Pawel Wocjan; Thomas Beth

2004-01-01

35

Unbiased sequential estimation of 1\\/p : Settlement of a conjecture  

Microsoft Academic Search

Summary  We present a complete characterization of the class of (unbounded) sampling plans providing unbiased (sequential) estimation\\u000a of the reciprocal of the Bernoulli parameterp. This settles a conjecture set forth by Sinha and Sinha (1975,Ann. Inst. Statist. Math.,27, 245–258) regarding the nature of such plans as sought out by Gupta (1967,Ann. Inst. Statist. Math.,19, 413–416). Incidentally, a special type of sampling

Bikas Kumar Sinha; Arup Bose

1985-01-01

36

Unbiased ?-leap methods for stochastic simulation of chemically reacting systems  

NASA Astrophysics Data System (ADS)

The ?-leap method first developed by Gillespie [D. T. Gillespie, J. Chem. Phys. 115, 1716 (2001)] can significantly speed up stochastic simulation of certain chemically reacting systems with acceptable losses in accuracy. Recently, several improved ?-leap methods, including the binomial, multinomial, and modified ?-leap methods, have been developed. However, in all these ?-leap methods, the mean of the number of times, Km, that the mth reaction channel fires during a leap is not equal to the true mean. Therefore, all existing ?-leap methods produce biased simulation results, which limit the simulation accuracy and speed. In this paper, we analyze the mean of Km based on the chemical master equation. Using this analytical result, we develop unbiased Poisson and binomial ?-leap methods. Moreover, we analyze the variance of Km, and then develop an unbiased Poisson/Gaussian/binomial ?-leap method to correct the errors in both the mean and variance of Km. Simulation results demonstrate that our unbiased ?-leap method can significantly improve simulation accuracy without sacrificing speed.

Xu, Zhouyi; Cai, Xiaodong

2008-04-01

37

Quantitating Glomerular Endothelial Fenestration: An Unbiased Stereological Approach  

PubMed Central

Background/Aims Glomerular endothelial cells are fenestrated, allowing for especially high transcellular hydraulic conductivity. Current knowledge about endothelial fenestration structural changes in disease conditions is limited, partly due to the absence of robust methodologies to quantitate these structures. Herein, we propose a novel method for estimating the percentage of endothelial fenestration. Methods An unbiased stereological method based on contiguity of two phases and surface area density estimation using isotropic uniform random line probes was developed. A line grid for intercept counting and classifying endothelial coverage of fenestrated versus non-fenestrated areas was designed. The method was applied to renal biopsies from 15 patients with Fabry disease and 9 normal living kidney donor controls. Results The percentage of glomerular capillary endothelial coverage which was fenestrated was lower in Fabry patients (43 ± 12%) versus controls (53 ± 9%; p = 0.047). The fraction of endothelial surface which was fenestrated was greater on the peripheral versus mesangial zones of the capillary walls in both Fabry patients (p = 0.00002) and controls (p = 0.0005). Conclusion The proposed method provides an unbiased tool to quantitate endothelial fenestration changes in glomeruli. The practical example introduced showed reduced glomerular endothelial fenestration in Fabry nephropathy.

Najafian, Behzad; Mauer, Michael

2011-01-01

38

Mutually unbiased projectors and duality between lines and bases in finite quantum systems  

NASA Astrophysics Data System (ADS)

Quantum systems with variables in the ring Z(d) are considered, and the concepts of weak mutually unbiased bases and mutually unbiased projectors are discussed. The lines through the origin in the Z(d)×Z(d) phase space, are classified into maximal lines (sets of d points), and sublines (sets of di points where di|d). The sublines are intersections of maximal lines. It is shown that there exists a duality between the properties of lines (resp., sublines), and the properties of weak mutually unbiased bases (resp., mutually unbiased projectors).

Shalaby, M.; Vourdas, A.

2013-10-01

39

Drug targets: single-cell transcriptomics hastens unbiased discovery  

PubMed Central

Drug discovery in neuro- and psychopharmacology is lagging, and the most commonly mentioned cause is the scarcity of drug targets. Using NextGen ‘Sequencing Based Single-Cell Transcriptomics’ (SBSCT), several hundred different receptors and channels can be identified in individual neurons, and the functional gene product can subsequently be validated. The use of single-cell transcriptome data to reveal the entire receptor repertoire is crucial, as the copy numbers of mRNAs encoding receptors are low and when cells are pooled, dilution of rare mRNAs leads to loss of signal. These overlooked receptors on key neurons often mediate robust effects that may be therapeutically useful. SBSCT also enables the identification of orphan receptors and can provide strong evidence for receptor heterodimers. Here, we compare SBSCT to other single-cell profiling methods. We argue that the unbiased nature of SBSCT makes it a powerful tool for the identification of new drug targets.

Bartfai, Tamas; Buckley, Peter T.; Eberwine, James

2011-01-01

40

Obtaining an unbiased redshift distribution for submm galaxies  

NASA Astrophysics Data System (ADS)

We request 36hr with ATCA to test a new method for determining an unbiased redshift distribution for submm galaxies (SMGs) - a critical parameter capable of breaking degeneracies in galaxy evolution models. Our method is based on the expectation that dusty ULIRGs will exhibit maser activity similar to that observed in other IR-luminous AGN. As well as determining redshifts, detections will allow us to estimate the mass of the central black hole (to compare with X-ray-based estimates), to pinpoint the maser relative to the synchrotron emission, and to explore any correlation between L(FIR) and L(H2O). The key to our project is the largest deep submm survey undertaken thus far - LESS - in the Extended Chandra Deep Field South. We propose to piggyback on the Huynh et al. 5-GHz survey of ECDFS, going 2.3x deeper in two pointings centred on over-densities of bright SMGs.

Ivison, Rob; Norris, Ray; Feain, Ilana; Huynh, Minh; Smail, Ian; Thomson, Alasdair

2009-07-01

41

Maximum likelihood: Extracting unbiased information from complex networks  

NASA Astrophysics Data System (ADS)

The choice of free parameters in network models is subjective, since it depends on what topological properties are being monitored. However, we show that the maximum likelihood (ML) principle indicates a unique, statistically rigorous parameter choice, associated with a well-defined topological feature. We then find that, if the ML condition is incompatible with the built-in parameter choice, network models turn out to be intrinsically ill defined or biased. To overcome this problem, we construct a class of safely unbiased models. We also propose an extension of these results that leads to the fascinating possibility to extract, only from topological data, the “hidden variables” underlying network organization, making them “no longer hidden.” We test our method on World Trade Web data, where we recover the empirical gross domestic product using only topological information.

Garlaschelli, Diego; Loffredo, Maria I.

2008-07-01

42

Group theoretical construction of mutually unbiased bases in Hilbert spaces of prime dimensions  

Microsoft Academic Search

Mutually unbiased bases in Hilbert spaces of finite dimensions are closely related to the quantal notion of complementarity. An alternative proof of existence of a maximal collection of (N +1 ) mutually unbiased bases in Hilbert spaces of prime dimension N is given by exploiting the finite Heisenberg group (also called the Pauli group) and the action of SL(2, ZN

43

An unbiased sample of bright southern compact steep spectrum and gigahertz peaked spectrum sources  

NASA Astrophysics Data System (ADS)

Compact Steep Spectrum (CSS) and Gigahertz Peaked Spectrum (GPS) sources are classes of compact, powerful, extragalactic objects. These sources are thought to be the earliest stages in the evolution of radio galaxies, capturing the ignition (or, in some cases, re-ignition) of the active galactic nucleus. As well as serving as probes of the early stages of large-scale radio sources, these sources are good, stable, amplitude calibrators for radio telescopes. We present an unbiased flux density limited (>1.5 Jy at 2.7 GHz) catalogue of these objects in the Southern hemisphere, including tabulated data, radio spectra, and where available, optical images and measurements. The catalogue contains 26 sources, consisting of two new candidates and 15 known CSS sources, and nine known GPS sources. We present new Australia Telescope Compact Array (ATCA) data on 10 of these 26 sources, and data on a further 42 sources which were excluded from our final sample. This bright sample will serve as a reference sample for comparison with subsequent faint (mJy level) samples of CSS and GPS candidates currently being compiled.

Randall, K. E.; Hopkins, A. M.; Norris, R. P.; Edwards, P. G.

2011-09-01

44

Unbiased approach for virus detection in skin lesions.  

PubMed

To assess presence of virus DNA in skin lesions, swab samples from 82 squamous cell carcinomas of the skin (SCCs), 60 actinic keratoses (AKs), paraffin-embedded biopsies from 28 SCCs and 72 kerathoacanthomas (KAs) and fresh-frozen biopsies from 92 KAs, 85 SCCs and 92 AKs were analyzed by high throughput sequencing (HTS) using 454 or Ion Torrent technology. We found total of 4,284 viral reads, out of which 4,168 were Human Papillomavirus (HPV)-related, belonging to 15 known (HPV8, HPV12, HPV20, HPV36, HPV38, HPV45, HPV57, HPV59, HPV104, HPV105, HPV107, HPV109, HPV124, HPV138, HPV147), four previously described putative (HPV 915 F 06 007 FD1, FA73, FA101, SE42) and two putatively new HPV types (SE46, SE47). SE42 was cloned, sequenced, designated as HPV155 and found to have 76% similarity to the most closely related known HPV type. In conclusion, an unbiased approach for viral DNA detection in skin tumors has found that, although some new putative HPVs were found, known HPV types constituted most of the viral DNA. PMID:23840382

Bzhalava, Davit; Johansson, Hanna; Ekström, Johanna; Faust, Helena; Möller, Birgitta; Eklund, Carina; Nordin, Peter; Stenquist, Bo; Paoli, John; Persson, Bengt; Forslund, Ola; Dillner, Joakim

2013-06-28

45

Antenna-coupled unbiased detectors for LW-IR regime  

NASA Astrophysics Data System (ADS)

At room temperature (300K), the electromagnetic (EM) radiation emitted by humans and other living beings peaks mostly in the long-wavelength infrared (LW-IR) regime. And since the atmosphere shows relatively little absorption in this band, applications such as target detection, tracking, active homing, and navigation in autonomous vehicles extensively use the LW-IR frequency range. The present research work is focused on developing antenna-based, uncooled, and unbiased detectors for the LW-IR regime. In the first part of this research, antenna-coupled metal-oxide-metal diodes (ACMOMD) are investigated. In response to the EM radiation, high-frequency antenna currents are induced in the antenna. An asymmetric-barrier Al-Al2O3-Pt MOM diode rectifies the antenna currents. Two different types of fabrication processes have been developed for ACMOMDs namely one-step lithography and two-step lithography. The major drawbacks of MOM-based devices include hard-to-control fabrication processes, generally very high zero-biased resistances, and vulnerability to electrostatic discharges, leading to unstable electrical characteristics. The second part of this research focuses on the development of unbiased LW-IR sensors based on the Seebeck effect. If two different metals are joined together at one end and their other ends are open-circuited, and if a non-zero temperature difference exists between the joined end and the open ends, then a non-zero open-circuit voltage can be measured between the open ends of the wires. Based on this effect, we have developed antenna-coupled nano-thermocouples (ACNTs) in which radiation-induced antenna currents produce polarization-dependent heating of the joined end of the two metals whereas the open ends remain at substrate temperature. This polarization-dependent heating induces polarization-dependent temperature difference between the joined end and the open ends of the metals leading to a polarization-dependent open-circuit voltage between the open ends of the metals. A CW CO2 laser tuned at 10.6 mum wavelength has been used for infrared characterization of these sensors. For these sensors, average responsivity of 22.7 mV/W, signal-to-noise (SNR) ratio of 29 dB, noise equivalent power (NEP) of 1.55 nW, and specific detectivity (D*) of 1.77x105 cm. Hz .W--1 were measured. ACNTs are expected to operate at frequencies much beyond 400 KHz. The third part of this research focuses on the effect of DC read-out interconnects on polarization characteristics of the planar dipole antennas. Different geometries of the interconnects present different electromagnetic boundary conditions to the antenna, and thus affect the far-field polarization characteristics of the antenna. Four designs of DC read-out interconnects are fabricated and their polarization-dependent IR responses are experimentally measured. The High Frequency Structure Simulator (HFSS) from ANSYS is used to simulate the polarization characteristics of the antenna with different read-out geometries.

Tiwari, Badri Nath

46

Unbiased Inclination Distributions for Objects in the Kuiper Belt  

NASA Astrophysics Data System (ADS)

Using data from the Deep Ecliptic Survey (DES), we investigate the inclination distributions of objects in the Kuiper Belt. We present a derivation for observational bias removal and use this procedure to generate unbiased inclination distributions for Kuiper Belt objects (KBOs) of different DES dynamical classes, with respect to the Kuiper Belt plane. Consistent with previous results, we find that the inclination distribution for all DES KBOs is well fit by the sum of two Gaussians, or a Gaussian plus a generalized Lorentzian, multiplied by sin i. Approximately 80% of KBOs are in the high-inclination grouping. We find that Classical object inclinations are well fit by sin i multiplied by the sum of two Gaussians, with roughly even distribution between Gaussians of widths 2.0+0.6 -0.5° and 8.1+2.6 -2.1°. Objects in different resonances exhibit different inclination distributions. The inclinations of Scattered objects are best matched by sin i multiplied by a single Gaussian that is centered at 19.1+3.9 -3.6° with a width of 6.9+4.1 -2.7°. Centaur inclinations peak just below 20°, with one exceptionally high-inclination object near 80°. The currently observed inclination distribution of the Centaurs is not dissimilar to that of the Scattered Extended KBOs and Jupiter-family comets, but is significantly different from the Classical and Resonant KBOs. While the sample sizes of some dynamical classes are still small, these results should begin to serve as a critical diagnostic for models of solar system evolution.

Gulbis, A. A. S.; Elliot, J. L.; Adams, E. R.; Benecchi, S. D.; Buie, M. W.; Trilling, D. E.; Wasserman, L. H.

2010-08-01

47

Unbiased Average Age-Appropriate Atlases for Pediatric Studies  

PubMed Central

Spatial normalization, registration, and segmentation techniques for Magnetic Resonance Imaging (MRI) often use a target or template volume to facilitate processing, take advantage of prior information, and define a common coordinate system for analysis. In the neuroimaging literature, the MNI305 Talairach-like coordinate system is often used as a standard template. However, when studying pediatric populations, variation from the adult brain makes the MNI305 suboptimal for processing brain images of children. Morphological changes occurring during development render the use of age-appropriate templates desirable to reduce potential errors and minimize bias during processing of pediatric data. This paper presents the methods used to create unbiased, age-appropriate MRI atlas templates for pediatric studies that represent the average anatomy for the age range of 4.5–18.5 years, while maintaining a high level of anatomical detail and contrast. The creation of anatomical T1-weighted, T2-weighted, and proton density-weighted templates for specific developmentally important age-ranges, used data derived from the largest epidemiological, representative (healthy and normal) sample of the U.S. population, where each subject was carefully screened for medical and psychiatric factors and characterized using established neuropsychological and behavioral assessments. . Use of these age-specific templates was evaluated by computing average tissue maps for gray matter, white matter, and cerebrospinal fluid for each specific age range, and by conducting an exemplar voxel-wise deformation-based morphometry study using 66 young (4.5–6.9 years) participants to demonstrate the benefits of using the age-appropriate templates. The public availability of these atlases/templates will facilitate analysis of pediatric MRI data and enable comparison of results between studies in a common standardized space specific to pediatric research.

Fonov, Vladimir; Evans, Alan C.; Botteron, Kelly; Almli, C. Robert; McKinstry, Robert C.; Collins, D. Louis

2010-01-01

48

Independent Unbiased Coin Flips From a Correlated Biased Source: a Finite State Markov Chain  

Microsoft Academic Search

von Neumann's trick for generating an absolutely unbiased coin from a biased one is this: 1. Toss the biased coin twice, getting 00, 01, 10, or 11. 2. If 00 or 11 occur, go back to step 1; else 3. Call 10 a H, 01 a T. Since p(H) = p(l)*p(O) = p(T), the output is unbiased. Example: 00 10

Manuel Blum

1984-01-01

49

Acceleration spectra for subduction zone earthquakes  

USGS Publications Warehouse

We estimate the source spectra of shallow earthquakes from digital recordings of teleseismic P wave groups, that is, P+pP+sP, by making frequency dependent corrections for the attenuation and for the interference of the free surface. The correction for the interference of the free surface assumes that the earthquake radiates energy from a range of depths. We apply this spectral analysis to a set of 12 subduction zone earthquakes which range in size from Ms = 6.2 to 8.1, obtaining corrected P wave acceleration spectra on the frequency band from 0.01 to 2.0 Hz. Seismic moment estimates from surface waves and normal modes are used to extend these P wave spectra to the frequency band from 0.001 to 0.01 Hz. The acceleration spectra of large subduction zone earthquakes, that is, earthquakes whose seismic moments are greater than 1027 dyn cm, exhibit intermediate slopes where u(w)???w5/4 for frequencies from 0.005 to 0.05 Hz. For these earthquakes, spectral shape appears to be a discontinuous function of seismic moment. Using reasonable assumptions for the phase characteristics, we transform the spectral shape observed for large earthquakes into the time domain to fit Ekstrom's (1987) moment rate functions for the Ms=8.1 Michoacan earthquake of September 19, 1985, and the Ms=7.6 Michoacan aftershock of September 21, 1985. -from Authors

Boatwright, J.; Choy, G. L.

1989-01-01

50

Characterization of fiducial states in prime dimensions via mutually unbiased bases  

NASA Astrophysics Data System (ADS)

In this paper, we present some new properties of fiducial states in prime dimensions. We parameterize fiducial operators on eigenvectors bases of displacement operators, which allows us to find a manifold ? of Hermitian operators satisfying Tr(?) = Tr(?2) = 1 for any ? in ?. This manifold contains the complete set of fiducial pure states in every prime dimension. Indeed, any quantum state ? ? 0 belonging to ? is a fiducial pure state. Also, we present an upper bound for every probability associated with the mutually unbiased decomposition of fiducial states. This bound allows us to prove that every fiducial state tends to be mutually unbiased to the maximal set of mutually unbiased bases in higher prime dimensions. Finally, we show that any ? in ? minimizes an entropic uncertainty principle related to the second-order Rényi entropy.

Goyeneche, D.; Salazar, R.; Delgado, A.

2013-03-01

51

Unbiased bases (Hadamards) for six-level systems: Four ways from Fourier  

SciTech Connect

In quantum mechanics some properties are maximally incompatible, such as the position and momentum of a particle or the vertical and horizontal projections of a two-level spin. Given any definite state of one property, the other property is completely random or unbiased. For N-level systems, the six-level ones are the smallest for which a tomographically efficient set of N+1 mutually unbiased bases has not been found. To facilitate the search, we numerically extend the classification of unbiased bases, or Hadamards, by incrementally adjusting relative phases in a standard basis. We consider the nonunitarity caused by small adjustments with a second order Taylor expansion and choose incremental steps within the four-dimensional null space of the curvature. In this way, we prescribe a numerical integration of a four-parameter set of Hadamards of order of 6.

Skinner, A. J.; Newell, V. A.; Sanchez, R. [Department of Physics, Skidmore College, Saratoga Springs, New York 12866 (United States)

2009-01-15

52

Mutually unbiased bases in six dimensions: The four most distant bases  

SciTech Connect

We consider the average distance between four bases in six dimensions. The distance between two orthonormal bases vanishes when the bases are the same, and the distance reaches its maximal value of unity when the bases are unbiased. We perform a numerical search for the maximum average distance and find it to be strictly smaller than unity. This is strong evidence that no four mutually unbiased bases exist in six dimensions. We also provide a two-parameter family of three bases which, together with the canonical basis, reach the numerically found maximum of the average distance, and we conduct a detailed study of the structure of the extremal set of bases.

Raynal, Philippe [Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 (Singapore); Lue Xin; Englert, Berthold-Georg [Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 (Singapore); Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 (Singapore)

2011-06-15

53

Generation of all sets of mutually unbiased bases for three-qubit systems  

NASA Astrophysics Data System (ADS)

We propose a new method of finding the mutually unbiased bases for three qubits. The key element is the construction of the table of striation-generating curves in the discrete phase space. We derive a system of equations in the Galois field GF(8) and show that the solutions of these equations are sufficient for the construction of the general sets of complete mutually unbiased bases. A few examples are presented in order to show how our algorithm works in the following cases: striation table with three and two axes, and one and no axis in the discrete phase space.

Ghiu, Iulia

2013-03-01

54

Calculation of Unbiased Clock-Variances in Uncalibrated Atomic Time Scale Algorithms  

NASA Astrophysics Data System (ADS)

We discuss the biased frequency variances or weights of clocks estimated from clock data referred to the ensemble time which is determined from an ensemble of the clocks without using a primary frequency standard, and show a calculation method to obtain the unbiased variances or weights by compensating for the biased variances. The method uses an atomic time scale algorithm based on a simply weighted average over the ensemble clocks, used only for the unbiased-variance calculation. Effects of frequency drifts on the calculation and weight corrections on an atomic time scale are also discussed. By computer simulations which use mixed processes of white-noise FM and flicker-noise FM the great effectiveness of the unbiased variance calculation is shown. An example of a time scale using six clock models are also shown by the simulation with an algorithm based on the time-error prediction for each clock between intervals without using a primary standard, in which the unbiased weights are adopted.

Yoshimura, K.

1980-07-01

55

Smooth Unbiased Multivariate Probability Simulators for Maximum Likelihood Estimation of Limited Dependent Variable Models  

Microsoft Academic Search

We apply a new simulation method that solves the multidimensional probability integrals that arise in maximum likelihood estimation of a broad class of limited dependent variable models. The simulation method has four key features: the simulated choice probabilities are unbiased; they are a continuous and differentiable function of the parameters of the model; they are bounded between 0 and 1;

Vassilis A. Hajivassiliou; Axel Borsch-Supan

1990-01-01

56

Reply to ''Comment on 'Mutually unbiased bases, orthogonal Latin squares, and hidden-variable models'''  

SciTech Connect

In this Reply to the preceding Comment by Hall and Rao [Phys. Rev. A 83, 036101 (2011)], we motivate terminology of our original paper and point out that further research is needed in order to (dis)prove the claimed link between every orthogonal Latin square of order being a power of a prime and a mutually unbiased basis.

Paterek, Tomasz [Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore (Singapore); Dakic, Borivoje; Brukner, Caslav [Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Wien (Austria); Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Wien (Austria)

2011-03-15

57

Best Linear Unbiased Estimators of the Parameters of the Logistic Distribution Using Order Statistics  

Microsoft Academic Search

This paper deals with the problem of estimating the mean and the standard deviation of the logistic distribution by using ordered observations in small samples. Linear unbiased estimators with minimum variance based on ordered observations are constructed both for the complete and the censored samples for sample sizes n = 2, 5, 10, 15, 20 and 25. The censored sample

S. S. Gupta; A. S. Qureishi; B. K. Shah

1967-01-01

58

Best Linear Unbiased Estimates of the Parameters of the Logistic Distribution Based on Selected Order Statistics  

Microsoft Academic Search

Coefficients, variances and efficiencies are provided for the best linear unbiased estimates (BLUE's) of the mean and standard deviation of the logistic distribution, with both unknown, based on four order statistics with ranks giving the maximum joint efficiency among all BLUE's based on four order statistics. Asymptotic joint efficiencies are compared for asymptotically best linear estimates (ABLE's) based on order

Lai K. Chan; N. N. Chan; E. R. Mead

1971-01-01

59

From Stein's Unbiased Risk Estimates to the Method of Generalized Cross Validation  

Microsoft Academic Search

This paper concerns the method of generalized cross validation (GCV), a promising way of choosing between linear estimates. Based on Stein estimates and the associated unbiased risk estimates (Stein, 1981), a new approach to GCV is developed. Many consistency results are obtained for the cross-validated (Steinized) estimates in the contexts of nearest-neighbor nonparametric regression, model selection, ridge regression, and smoothing

Ker-Chau Li

1985-01-01

60

Walking in Facebook: A Case Study of Unbiased Sampling of OSNs  

Microsoft Academic Search

With more than 250 million active users, Facebook (FB) is currently one of the most important online social networks. Our goal in this paper is to obtain a representative (unbiased) sample of Facebook users by crawling its social graph. In this quest, we consider and implement several candidate techniques. Two approaches that are found to perform well are the Metropolis-Hasting

Minas Gjoka; Maciej Kurant; Carter T. Butts; Athina P. Markopoulou

2010-01-01

61

Best linear unbiased estimation filters with FIR structures for state space signal models  

Microsoft Academic Search

In this paper, a new best linear unbiased estimation (BLUE) finite impulse response (FIR) filter called the BLUE FIR filter is proposed for discrete-time state space signal models with system noises and inputs. The proposed BLUE FIR filter is a linear function of only the finite measurements and inputs on the most recent horizon, does not require a priori information

Wook Hyun Kwon; Pyung Soo Kim; Soo Hee Han

1999-01-01

62

Operational link between mutually unbiased bases and symmetric informationally complete positive operator-valued measures  

NASA Astrophysics Data System (ADS)

We exhibit an operational connection between mutually unbiased bases and symmetric informationally complete positive operator-valued measures. Assuming that the latter exists, we show that there is a strong link between these two structures in all prime power dimensions. We also demonstrate that a similar link cannot exist in dimension 6.

Beneduci, Roberto; Bullock, Thomas J.; Busch, Paul; Carmeli, Claudio; Heinosaari, Teiko; Toigo, Alessandro

2013-09-01

63

Unbiased metabolite profiling by liquid chromatography-quadrupole time-of-flight mass spectrometry and multivariate data analysis for herbal authentication: classification of seven Lonicera species flower buds.  

PubMed

Plant-based medicines become increasingly popular over the world. Authentication of herbal raw materials is important to ensure their safety and efficacy. Some herbs belonging to closely related species but differing in medicinal properties are difficult to be identified because of similar morphological and microscopic characteristics. Chromatographic fingerprinting is an alternative method to distinguish them. Existing approaches do not allow a comprehensive analysis for herbal authentication. We have now developed a strategy consisting of (1) full metabolic profiling of herbal medicines by rapid resolution liquid chromatography (RRLC) combined with quadrupole time-of-flight mass spectrometry (QTOF MS), (2) global analysis of non-targeted compounds by molecular feature extraction algorithm, (3) multivariate statistical analysis for classification and prediction, and (4) marker compounds characterization. This approach has provided a fast and unbiased comparative multivariate analysis of the metabolite composition of 33-batch samples covering seven Lonicera species. Individual metabolic profiles are performed at the level of molecular fragments without prior structural assignment. In the entire set, the obtained classifier for seven Lonicera species flower buds showed good prediction performance and a total of 82 statistically different components were rapidly obtained by the strategy. The elemental compositions of discriminative metabolites were characterized by the accurate mass measurement of the pseudomolecular ions and their chemical types were assigned by the MS/MS spectra. The high-resolution, comprehensive and unbiased strategy for metabolite data analysis presented here is powerful and opens the new direction of authentication in herbal analysis. PMID:22658297

Gao, Wen; Yang, Hua; Qi, Lian-Wen; Liu, E-Hu; Ren, Mei-Ting; Yan, Yu-Ting; Chen, Jun; Li, Ping

2012-05-14

64

Atomic Spectra  

NSDL National Science Digital Library

This page from Hyperphysics contains images depicting the light emitted by several elements and their respective spectra. The page also provides a description of how the size of a holographic image scales with the wavelength of the light used to observe it.

Nave, Carl R.

2010-03-12

65

Atomic Spectra  

NSDL National Science Digital Library

In this Flash animation the user can view the atomic emission spectra (400-700nm) of eight different elements. A dragable marker allows the user to approximate the wavelength of the various spectral lines. The effect of resolution can be examined in the sodium spectrum in the region 550-600nm.

66

Fluorescence Spectra  

NSDL National Science Digital Library

This experiment uses the Tracker video analysis and modeling tool to explore the phenomenon of fluorescence and its application in fluorescent lamps. For each of five different visible spectra, students (a) observe the spectrum directly, (b) measure its brightness versus wavelength in Tracker, and (c) answer both qualitative and quantitative questions about it. The spectra include a fluorescent dye with laser and UV illumination, a mercury lamp and two fluorescent lamps, all with red and green laser spots added for easy calibration. For more information, see the AAPT presentation. The zip file includes the lab instructions, spectrum images and Tracker data files. This requires Tracker version 4.62 or higher. Tracker installers are available for Windows, Mac and Linux from ComPADRE or the Tracker web site (http://www.cabrillo.edu/~dbrown/tracker/).

Brown, Douglas

2012-01-17

67

Mutually unbiased bases, orthogonal Latin squares, and hidden-variable models  

NASA Astrophysics Data System (ADS)

Mutually unbiased bases encapsulate the concept of complementarity—the impossibility of simultaneous knowledge of certain observables—in the formalism of quantum theory. Although this concept is at the heart of quantum mechanics, the number of these bases is unknown except for systems of dimension being a power of a prime. We develop the relation between this physical problem and the mathematical problem of finding the number of mutually orthogonal Latin squares. We derive in a simple way all known results about the unbiased bases, find their lower number, and disprove the existence of certain forms of the bases in dimensions different than power of a prime. Using the Latin squares, we construct hidden-variable models which efficiently simulate results of complementary quantum measurements.

Paterek, Tomasz; Daki?, Borivoje; Brukner, ?aslav

2009-01-01

68

Test of mutually unbiased bases for six-dimensional photonic quantum systems.  

PubMed

In quantum information, complementarity of quantum mechanical observables plays a key role. The eigenstates of two complementary observables form a pair of mutually unbiased bases (MUBs). More generally, a set of MUBs consists of bases that are all pairwise unbiased. Except for specific dimensions of the Hilbert space, the maximal sets of MUBs are unknown in general. Even for a dimension as low as six, the identification of a maximal set of MUBs remains an open problem, although there is strong numerical evidence that no more than three simultaneous MUBs do exist. Here, by exploiting a newly developed holographic technique, we implement and test different sets of three MUBs for a single photon six-dimensional quantum state (a "qusix"), encoded exploiting polarization and orbital angular momentum of photons. A close agreement is observed between theory and experiments. Our results can find applications in state tomography, quantitative wave-particle duality, quantum key distribution. PMID:24067548

D'Ambrosio, Vincenzo; Cardano, Filippo; Karimi, Ebrahim; Nagali, Eleonora; Santamato, Enrico; Marrucci, Lorenzo; Sciarrino, Fabio

2013-09-25

69

Higher-dimensional orbital-angular-momentum-based quantum key distribution with mutually unbiased bases  

NASA Astrophysics Data System (ADS)

We present an experimental study of higher-dimensional quantum key distribution protocols based on mutually unbiased bases, implemented by means of photons carrying orbital angular momentum. We perform (d+1) mutually unbiased measurements in a classically simulated prepare-and-measure scheme and on a pair of entangled photons for dimensions ranging from d=2 to 5. In our analysis, we pay attention to the detection efficiency and photon pair creation probability. As security measures, we determine from experimental data the average error rate, the mutual information shared between the sender and receiver, and the secret key generation rate per photon. We demonstrate that increasing the dimension leads to an increased information capacity as well as higher key generation rates per photon. However, we find that the benefit of increasing the dimension is limited by practical implementation considerations, which in our case results in deleterious effects observed beyond a dimension of d=4.

Mafu, Mhlambululi; Dudley, Angela; Goyal, Sandeep; Giovannini, Daniel; McLaren, Melanie; Padgett, Miles J.; Konrad, Thomas; Petruccione, Francesco; Lütkenhaus, Norbert; Forbes, Andrew

2013-09-01

70

Rapid purification of quantum systems by measuring in a feedback-controlled unbiased basis  

SciTech Connect

Rapid purification by feedback--specifically, reducing the mean impurity faster than by measurement alone--can be achieved by choosing the eigenbasis of the density matrix to be unbiased relative to the measurement basis. Here we further examine the protocol introduced by Combes and Jacobs [Phys. Rev. Lett. 96, 010504 (2006)] involving continuous measurement of the observable J{sub z} for a D-dimensional system. We rigorously rederive the lower bound (2/3)(D+1) on the achievable speedup factor and also an upper bound, namely D{sup 2}/2, for all feedback protocols that use measurements in unbiased bases. Finally, we extend our results to n independent measurements on a register of n qubits and derive an upper bound on the achievable speedup factor that scales linearly with n.

Combes, Joshua; Wiseman, Howard M. [Centre for Quantum Computer Technology, Brisbane (Australia); Centre for Quantum Dynamics, Griffith University, Brisbane, Queensland 4111 (Australia); Jacobs, Kurt [Department of Physics, University of Massachusetts at Boston, 100 Morrissey Boulevard, Boston, Massachusetts 02125 (United States); O'Connor, Anthony J. [School of Biomolecular and Physical Sciences, Griffith University, Brisbane, Queensland 4111 (Australia)

2010-08-15

71

Test of mutually unbiased bases for six-dimensional photonic quantum systems  

PubMed Central

In quantum information, complementarity of quantum mechanical observables plays a key role. The eigenstates of two complementary observables form a pair of mutually unbiased bases (MUBs). More generally, a set of MUBs consists of bases that are all pairwise unbiased. Except for specific dimensions of the Hilbert space, the maximal sets of MUBs are unknown in general. Even for a dimension as low as six, the identification of a maximal set of MUBs remains an open problem, although there is strong numerical evidence that no more than three simultaneous MUBs do exist. Here, by exploiting a newly developed holographic technique, we implement and test different sets of three MUBs for a single photon six-dimensional quantum state (a “qusix”), encoded exploiting polarization and orbital angular momentum of photons. A close agreement is observed between theory and experiments. Our results can find applications in state tomography, quantitative wave-particle duality, quantum key distribution.

D'Ambrosio, Vincenzo; Cardano, Filippo; Karimi, Ebrahim; Nagali, Eleonora; Santamato, Enrico; Marrucci, Lorenzo; Sciarrino, Fabio

2013-01-01

72

Mean king's problem with mutually unbiased bases and orthogonal Latin squares  

NASA Astrophysics Data System (ADS)

The mean king’s problem with maximal mutually unbiased bases (MUB’s) in general dimension d is investigated. It is shown that a solution of the problem exists if and only if the maximal number (d+1) of orthogonal Latin squares exists. This implies that there is no solution in d=6 or d=10 dimensions even if the maximal number of MUB’s exists in these dimensions.

Hayashi, A.; Horibe, M.; Hashimoto, T.

2005-05-01

73

Reply to ``Comment on `Mutually unbiased bases, orthogonal Latin squares, and hidden-variable models' ''  

NASA Astrophysics Data System (ADS)

In this Reply to the preceding Comment by Hall and Rao [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.83.036101 83, 036101 (2011)], we motivate terminology of our original paper and point out that further research is needed in order to (dis)prove the claimed link between every orthogonal Latin square of order being a power of a prime and a mutually unbiased basis.

Paterek, Tomasz; Daki?, Borivoje; Brukner, ?aslav

2011-03-01

74

Comment on ''Mutually unbiased bases, orthogonal Latin squares, and hidden-variable models''  

SciTech Connect

In a recent article Paterek, Dakic, and Brukner [Phys. Rev. A 79, 012109 (2009)] show an algorithm for generating mutually unbiased bases from sets of orthogonal Latin squares. They claim that this algorithm works for every set of orthogonal Latin squares. We show that the algorithm only works for particular sets of orthogonal Latin squares. Furthermore, the algorithm is a more readable version of work previously published [Phys. Rev. A 70, 062101 (2004)].

Hall, Joanne L.; Rao, Asha [School of Mathematical and Geospatial Sciences, RMIT University, GPO Box 2476V, Melbourne, 3001 (Australia)

2011-03-15

75

Comment on "Unbiased statistical analysis for multi-stage proteomic search strategies".  

PubMed

Everett et al. recently reported on a statistical bias that arises in the target-decoy approach to false discovery rate estimation in two-pass proteomics search strategies as exemplified by X!Tandem. This bias can cause serious underestimation of the false discovery rate. We argue here that the "unbiased" solution proposed by Everett et al., however, is also biased and under certain circumstances can also result in a serious underestimate of the FDR, especially at the protein level. PMID:21288048

Bern, Marshall; Kil, Yong J

2011-02-21

76

Generalized approach for using unbiased symmetric metrics with negative values: normalized mean bias factor and normalized mean absolute error factor  

EPA Science Inventory

Unbiased symmetric metrics provide a useful measure to quickly compare two datasets, with similar interpretations for both under and overestimations. Two examples include the normalized mean bias factor and normalized mean absolute error factor. However, the original formulations...

77

On the connection between mutually unbiased bases and orthogonal Latin squares  

NASA Astrophysics Data System (ADS)

We offer a piece of evidence that the problems of finding the number of mutually unbiased bases (MUB) and mutually orthogonal Latin squares (MOLS) might not be equivalent. We study a particular procedure that has been shown to relate the two problems and generates complete sets of MUB in power-of-prime dimensions and three MUB in dimension six. For these cases, every square from an augmented set of MOLS has a corresponding MUB. We show that this no longer holds for certain composite dimensions.

Paterek, T.; Paw?owski, M.; Grassl, M.; Brukner, ?.

2010-09-01

78

Comment on ``Mutually unbiased bases, orthogonal Latin squares, and hidden-variable models''  

NASA Astrophysics Data System (ADS)

In a recent article Paterek, Daki?, and Brukner [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.79.012109 79, 012109 (2009)] show an algorithm for generating mutually unbiased bases from sets of orthogonal Latin squares. They claim that this algorithm works for every set of orthogonal Latin squares. We show that the algorithm only works for particular sets of orthogonal Latin squares. Furthermore, the algorithm is a more readable version of work previously published [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.70.062101 70, 062101 (2004)].

Hall, Joanne L.; Rao, Asha

2011-03-01

79

Binding region of alanopine dehydrogenase predicted by unbiased molecular dynamics simulations of ligand diffusion.  

PubMed

Opine dehydrogenases catalyze the reductive condensation of pyruvate with l-amino acids. Biochemical characterization of alanopine dehydrogenase from Arenicola marina revealed that this enzyme is highly specific for l-alanine. Unbiased molecular dynamics simulations with a homology model of alanopine dehydrogenase captured the binding of l-alanine diffusing from solvent to a putative binding region near a distinct helix-kink-helix motif. These results and sequence comparisons reveal how mutations and insertions within this motif dictate the l-amino acid specificity. PMID:24066861

Gohlke, Holger; Hergert, Ulrike; Meyer, Tatu; Mulnaes, Daniel; Grieshaber, Manfred K; Smits, Sander H J; Schmitt, Lutz

2013-09-25

80

Genomic best linear unbiased prediction (gBLUP) for the estimation of genomic breeding values.  

PubMed

Genomic best linear unbiased prediction (gBLUP) is a method that utilizes genomic relationships to estimate the genetic merit of an individual. For this purpose, a genomic relationship matrix is used, estimated from DNA marker information. The matrix defines the covariance between individuals based on observed similarity at the genomic level, rather than on expected similarity based on pedigree, so that more accurate predictions of merit can be made. gBLUP has been used for the prediction of merit in livestock breeding, may also have some applications to the prediction of disease risk, and is also useful in the estimation of variance components and genomic heritabilities. PMID:23756897

Clark, Samuel A; van der Werf, Julius

2013-01-01

81

Approximating the Best Linear Unbiased Estimator of Non-Gaussian Signals with Gaussian Noise  

NASA Astrophysics Data System (ADS)

Obtaining the best linear unbiased estimator (BLUE) of noisy signals is a traditional but powerful approach to noise reduction. Explicitly computing the BLUE usually requires the prior knowledge of the noise covariance matrix and the subspace to which the true signal belongs. However, such prior knowledge is often unavailable in reality, which prevents us from applying the BLUE to real-world problems. To cope with this problem, we give a practical procedure for approximating the BLUE without such prior knowledge. Our additional assumption is that the true signal follows a non-Gaussian distribution while the noise is Gaussian.

Sugiyama, Masashi; Kawanabe, Motoaki; Blanchard, Gilles; Müller, Klaus-Robert

82

Discrete phase-space structure of n-qubit mutually unbiased bases  

SciTech Connect

We work out the phase-space structure for a system of n qubits. We replace the field of real numbers that label the axes of the continuous phase space by the finite field GF(2{sup n}) and investigate the geometrical structures compatible with the notion of unbiasedness. These consist of bundles of discrete curves intersecting only at the origin and satisfying certain additional properties. We provide a simple classification of such curves and study in detail the four- and eight-dimensional cases, analyzing also the effect of local transformations. In this way, we provide a comprehensive phase-space approach to the construction of mutually unbiased bases for n qubits.

Klimov, A.B.; Romero, J.L. [Departamento de Fisica, Universidad de Guadalajara, 44420 Guadalajara, Jalisco (Mexico); Bjoerk, G. [School of Information and Communication Technology, Royal Institute of Technology (KTH), Electrum 229, SE-164 40 Kista (Sweden); Sanchez-Soto, L.L. [Departamento de Optica, Facultad de Fisica, Universidad Complutense, 28040 Madrid (Spain)], E-mail: lsanchez@fis.ucm.es

2009-01-15

83

MR images denoising using DCT-based unbiased nonlocal means filter  

NASA Astrophysics Data System (ADS)

The non-local means (NLM) filter has been proven to be an efficient feature-preserved denoising method and can be applied to remove noise in the magnetic resonance (MR) images. To suppress noise more efficiently, we present a novel NLM filter by using a low-pass filtered and low dimensional version of neighborhood for calculating the similarity weights. The discrete cosine transform (DCT) is used as a smoothing kernel, allowing both improvements in similarity estimation and computational speed-up. Experimental results show that the proposed filter achieves better denoising performance in MR Images compared to others filters, such as recently proposed NLM filter and unbiased NLM (UNLM) filter.

Zheng, Xiuqing; Hu, Jinrong; Zhou, Jiuliu

2013-03-01

84

Efficient calculation of unbiased expectation values in diffusion quantum Monte Carlo  

NASA Astrophysics Data System (ADS)

Despite the proven utility of quantum Monte Carlo methods in addressing the quantum many-body problem, many important observables are difficult to calculate due to the presence of large, and sometimes divergent, statistical errors. The present state of the art allows the construction of renormalized estimators which result in finite variances, but which invariably include some systematic bias. We present a simple method for calculating unbiased expectation values of local operators in the diffusion quantum Monte Carlo method which is applicable to both bare and renormalized estimators, allowing the accurate calculation of important properties such as forces.

Per, Manolo C.; Snook, Ian K.; Russo, Salvy P.

2012-11-01

85

Unbiased application of the transmission/disequilibrium test to multilocus haplotypes.  

PubMed Central

When the transmission/disequilibrium test (TDT) is applied to multilocus haplotypes, a bias may be introduced in some families for which both parents have the same heterozygous genotype at some locus. The bias occurs because haplotypes can only be deduced from certain offspring, with the result that the transmissions of the two parental haplotypes are not independent. We obtain an unbiased TDT for individual haplotypes by calculating the correct variance for the transmission count within a family, using information from multiple siblings if they are available. An existing correction for dependence between siblings in the presence of linkage is retained. To obtain an unbiased multihaplotype TDT, we must either count transmissions from one randomly chosen parent or count all transmissions and estimate the significance level empirically. Alternatively, we may use missing-data techniques to estimate uncertain haplotypes, but these methods are not robust to population stratification. An illustration using data from the insulin-gene region in type 1 diabetes shows that the validity and power of the TDT may vary by an order of magnitude, depending on the method of analysis.

Dudbridge, F; Koeleman, B P; Todd, J A; Clayton, D G

2000-01-01

86

Quantitative Assessment of In-solution Digestion Efficiency Identifies Optimal Protocols for Unbiased Protein Analysis.  

PubMed

The majority of mass spectrometry-based protein quantification studies uses peptide-centric analytical methods and thus strongly relies on efficient and unbiased protein digestion protocols for sample preparation. We present a novel objective approach to assess protein digestion efficiency using a combination of qualitative and quantitative liquid chromatography-tandem MS methods and statistical data analysis. In contrast to previous studies we employed both standard qualitative as well as data-independent quantitative workflows to systematically assess trypsin digestion efficiency and bias using mitochondrial protein fractions. We evaluated nine trypsin-based digestion protocols, based on standard in-solution or on spin filter-aided digestion, including new optimized protocols. We investigated various reagents for protein solubilization and denaturation (dodecyl sulfate, deoxycholate, urea), several trypsin digestion conditions (buffer, RapiGest, deoxycholate, urea), and two methods for removal of detergents before analysis of peptides (acid precipitation or phase separation with ethyl acetate). Our data-independent quantitative liquid chromatography-tandem MS workflow quantified over 3700 distinct peptides with 96% completeness between all protocols and replicates, with an average 40% protein sequence coverage and an average of 11 peptides identified per protein. Systematic quantitative and statistical analysis of physicochemical parameters demonstrated that deoxycholate-assisted in-solution digestion combined with phase transfer allows for efficient, unbiased generation and recovery of peptides from all protein classes, including membrane proteins. This deoxycholate-assisted protocol was also optimal for spin filter-aided digestions as compared with existing methods. PMID:23792921

León, Ileana R; Schwämmle, Veit; Jensen, Ole N; Sprenger, Richard R

2013-06-21

87

Videotaped interrogations and confessions: does a dual-camera approach yield unbiased and accurate evaluations?  

PubMed

Although an equal-focus camera perspective-suspect and interrogator each displayed in profile-produces relatively unbiased assessments of videotaped interrogations-confessions, many in law enforcement may consider it less than satisfactory because a full-face view of the suspect is precluded and thus potentially important information revealed in his or her expressions may be unavailable for fact finders' consideration. The present research investigated whether a dual-camera approach, wherein the full faces of both the suspect and interrogator are presented in a split-screen format simultaneously, is a viable alternative to an equal-focus format. Experiment 1 in fact demonstrated that the dual-camera approach does produce relatively unbiased assessments of voluntariness and guilt. However, Experiment 2 revealed that the dual-camera approach was one of the poorest presentation formats in terms of its impact on the ability to accurately distinguish between true and false confessions. Policy recommendations based on the present and previous research are presented. PMID:19387972

Snyder, Celeste J; Lassiter, G Daniel; Lindberg, Matthew J; Pinegar, Shannon K

88

Unbiased identification of finite impulse response linear systems operating in closed-loop.  

PubMed

The force and position data issued to construct models of joint dynamics are often obtained from closed-loop experiments, where the joint position is perturbed using an actuator configured as a position servo. If the position servo is orders of magnitude staffer than the joint, as is often the case, it is possible to treat the data as if they were obtained in open loop. It may be more relevant to study joint dynamics in compliant environments. This can be accomplished by adding an admittance controller, programmed to simulate a compliant environment, into the servo. Under these conditions, the presence of feedback cannot be ignored. Unbiased estimates of a system can be directly obtained from closed-loop data using the prediction error method. However, this is not true, in general, when linear regression or correlation-based analysis is used to fit nonparametric time- or frequency domain models. We develop a prediction error minimization based identification method for a nonparametric time-domain model, augmented with a parametric noise model. Simulations suggest that the method produces unbiased estimates of the dynamics of a system operating inside a feedback loop, even though linear regression results in substantial biases. PMID:17946938

Westwick, David T; Perreault, Eric J

2006-01-01

89

Domain motion of individual F1-ATPase ?-subunits during unbiased molecular dynamics simulations  

PubMed Central

F1-ATPase is the catalytic domain of F1Fo-ATP synthase and consists of an hexameric arrangement of three non-catalytic ? and three catalytic ? subunits. We have used unbiased molecular dynamics simulations with a total simulation time of 900 ns to investigate the dynamic relaxation properties of isolated ?-subunits as a step toward explaining the function of the integral F1 unit. To this end, we simulated the open (?E) and the closed (?TP) conformations under unbiased conditions for up to 120 ns each using several samples. The simulations confirm that nucleotide-free ?E retains its open configuration over the course of the simulations. The same is true when the neighbouring ? subunits are included. The nucleotide-depleted as well as the nucleotide-bound isolated ?TP subunits show a significant trend toward the open conformation during our simulations, with one trajectory per case opening completely. Hence, our simulations suggest that the equilibrium conformation of a nucleotide-free ?-subunit is the open conformation and that the transition from the closed to the open conformation can occur on a timescale of a few tens of nanoseconds.

Kleinekathofer, Ulrich; Isralewitz, Barry; Dittrich, Markus; Schulten, Klaus

2011-01-01

90

Field propagation with nearly constant Gaussian beam parameters in unbiased self-defocusing photorefractive media  

NASA Astrophysics Data System (ADS)

Optical devices, where light controls light, are of interest to the computing and communications industries due to their potential to vastly improve information capacity and processing speed. One such device is an optical logic gate, based on the interactions of low divergence fields in photorefractive media. Presently, bright solitons in self-focusing photorefractive media offer one attractive possibility. A wide variety of other low divergence fields have also been outlined in recent literature, however, no theoretical model of a single bright soliton propagating in unbiased selfdefocusing photorefractive media is currently available. Evidence is presented of self-defocusing photorefractive media as an intensity dependent Gradient-Index (GRIN) lens with a negative power. Using this model, we outline conditions for the change in the complex beam parameter, and consequently the area and wavefront curvature, of the Gaussian beam to be minimised as it propagates through the selfdefocusing media. This is the first instance where self-defocusing photorefractive media has been modelled as an intensity dependent GRIN lens, and where a low divergence field propagating through unbiased self-defocusing media with a constant complex Gaussian beam parameter has been described.

Jones, Michael W.; Jaatinen, Esa

2008-01-01

91

Construction of mutually unbiased bases with cyclic symmetry for qubit systems  

SciTech Connect

For the complete estimation of arbitrary unknown quantum states by measurements, the use of mutually unbiased bases has been well established in theory and experiment for the past 20 years. However, most constructions of these bases make heavy use of abstract algebra and the mathematical theory of finite rings and fields, and no simple and generally accessible construction is available. This is particularly true in the case of a system composed of several qubits, which is arguably the most important case in quantum information science and quantum computation. In this paper, we close this gap by providing a simple and straightforward method for the construction of mutually unbiased bases in the case of a qubit register. We show that our construction is also accessible to experiments, since only Hadamard and controlled-phase gates are needed, which are available in most practical realizations of a quantum computer. Moreover, our scheme possesses the optimal scaling possible, i.e., the number of gates scales only linearly in the number of qubits.

Seyfarth, Ulrich [Institut fuer Angewandte Physik, Technische Universitaet Darmstadt, Hochschulstrasse 4a, D-64289 Darmstadt (Germany); Ranade, Kedar S. [Institut fuer Quantenphysik, Universitaet Ulm, Albert-Einstein-Allee 11, D-89081 Ulm (Germany)

2011-10-15

92

Beta Spectra. II-Positron Spectra.  

National Technical Information Service (NTIS)

Using the Fermi theory of beta decay, the beta spectra for 30 positron emitters have been computed, introducing a correction factor for unique forbidden transitions. The spectra are ploted vs. energy, once normalised, and tabulated with the related Fermi ...

A. Grau E. Garcia-Torano

1981-01-01

93

Obtaining An Unbiased Measurement of the Position Of SgrA*-IR  

NASA Astrophysics Data System (ADS)

We present an analysis of short, infrared, exposures of a field containing, SgrA*-IR, the emissive source associated with the Milky Way's central supermassive black hole, aimed at obtaining an unbiased measurement of its location. Such a measurement would nail down one of the key parameters in modeling our Galaxy's central potential. It is well known that the observed position of this emission in deep images is significantly biased due to underlying stars. We have examined the positional bias of SgrA*-IR and attempted to find an accurate IR position by taking advantage of its photometric variability. We find that the position is less biased when Sgr A*-IR is in the bright state. With this new technique, the position of Sgr A*-IR is now much more consistent with the position of Sgr A*-Radio and the position obtained in unconstrained models of the orbital motion of the short period star S0-2.

Phifer, Kimberly A.; Ghez, A. M.; Yelda, S.; Do, T.

2010-01-01

94

Unbiased X-ray sampling of stars within 25 parsecs of the Sun. Final Report  

SciTech Connect

A search of all of the Einstein Observatory IPC and HRI fields for untargeted stars in the Woolley, et al., Catalogue of the nearby stars is reported. Optical data and IPC coordinates, flux density F sub x, and luminosity L sub x, or upper limits, are tabulated for 126 single or blended systems, and HRI results for a few of them. IPC luminosity functions are derived for the systems, for 193 individual stars in the systems (with L sub x shared equally among blended components), and for 63 individual M dwarfs. These stars have relatively large x-ray flux densities that are free of interstellar extinction, because they are nearby, but they are otherwise unbiased with respect to the x-ray properties that are found in a defined small space around the Sun.

Johnson, H.M.

1985-08-01

95

Solution to the mean king's problem with mutually unbiased bases for arbitrary levels  

NASA Astrophysics Data System (ADS)

The mean king’s problem with mutually unbiased bases is reconsidered for arbitrary d -level systems. Hayashi [Phys. Rev. A 71, 052331 (2005)] related the problem to the existence of a maximal set of d-1 mutually orthogonal Latin squares, in their restricted setting that allows only measurements of projection-valued measures. However, we then cannot find a solution to the problem when, e.g., d=6 or d=10 . In contrast to their result, we show that the king’s problem always has a solution for arbitrary levels if we also allow positive operator-valued measures. In constructing the solution, we use orthogonal arrays in combinatorial design theory.

Kimura, Gen; Tanaka, Hajime; Ozawa, Masanao

2006-05-01

96

Large and kinematically unbiased samples of G and K type stars. I - The dwarfs  

NASA Astrophysics Data System (ADS)

Four-color, H?, and (R,I) photometry has been obtained for some 5000 stars in four kinematically unbiased samples; Bright Star Catalogue ("bright star" sample), South Galactic Pole ("SGP" sample), selected areas at +15° declination ("Griffin" sample), and HD stars with Mphot = 8.5 to 8.6 mag inclusive ("Moore-Paddock-Wayman" or MPW sample). The present discussion involves the little-evolved main-sequence stars which constitute only some 10% of the overall sample. The luminosity and abundance parameters are calibrated with the Hyades supercluster, the Sirius supercluster, the Wolf 630 group, the Arcturus group, and Kapteyn's Star Group. Results of possible interest from the calibrating groups and superclusters are presented. The distributions of the abundances and space motions of the sample stars are discussed.

Eggen, O. J.

1986-10-01

97

Cross cultural communication to help physician assistants provide unbiased health care.  

PubMed

Teaching cross cultural communication typically involves instruction in differences between groups. As part of this course in cross cultural communication, six specific underserved population groups are introduced to students as a cultural experience. Additionally, instruction is provided to sensitize students to their personal biases and prejudices through videotaped mock interviews. The combination of instruction and experience forms a paradigm for teaching cross cultural communication in a way that has personal and immediate impact on faculty members and students. The model, "Differences + Discomforts = Discoveries," inhibits factionalizing and promotes depth of knowledge about underserved groups as well as personal awareness of prejudicial feelings. As a result, students learn techniques to provide unbiased health care to these, and other, populations. PMID:1346725

Stumpf, S H; Bass, K

98

A CURE for Noisy Magnetic Resonance Images: Chi-Square Unbiased Risk Estimation.  

PubMed

n this article we derive an unbiased expression for the expected mean-squared error associated with continuously differentiable estimators of the noncentrality parameter of a chisquare random variable. We then consider the task of denoising squared-magnitude magnetic resonance image data, which are well modeled as independent noncentral chi-square random variables on two degrees of freedom. We consider two broad classes of linearly parameterized shrinkage estimators that can be optimized using our risk estimate, one in the general context of undecimated filterbank transforms, and another in the specific case of the unnormalized Haar wavelet transform. The resultant algorithms are computationally tractable and improve upon most state-of-the-art methods for both simulated and actual magnetic resonance image data. PMID:22491082

Luisier, F; Blu, T; Wolfe, P J

2012-04-05

99

Insights from WISP, an Unbiased Search for Distant Emission-line Galaxies  

NASA Astrophysics Data System (ADS)

The search for true physical pairs of galaxies at high redshifts has been greatly hindered by the difficulty of obtaining good spectroscopic redshifts. Multi-object near-infrared spectroscopy is especially effective, since it reaches the strongest rest-frame spectral features, especially emission lines. From ground-based telescopes, this is still very difficult to obtain for faint galaxies. However, the near-IR grism spectrographs on Hubble Space Telescope are ideal for a large, unbiased survey for galaxy groups and pairs. Without any pre-selection based on continuum properties, slitless spectroscopic surveys are extremely effective at uncovering large numbers of extreme dwarf galaxies, with very high specific star formation rates, and very low metallicities. We discuss preliminary results on pairs and other properties of galaxies found in the most ambitious of these surveys, the WFC-3 Infrared Spectroscopic Parallels (WISP).

Malkan, M.; WISP Team

2013-10-01

100

A CURE for Noisy Magnetic Resonance Images: Chi-Square Unbiased Risk Estimation  

NASA Astrophysics Data System (ADS)

In this article we derive an unbiased expression for the expected mean-squared error associated with continuously differentiable estimators of the noncentrality parameter of a chi-square random variable. We then consider the task of denoising squared-magnitude magnetic resonance image data, which are well modeled as independent noncentral chi-square random variables on two degrees of freedom. We consider two broad classes of linearly parameterized shrinkage estimators that can be optimized using our risk estimate, one in the general context of undecimated filterbank transforms, and another in the specific case of the unnormalized Haar wavelet transform. The resultant algorithms are computationally tractable and improve upon state-of-the-art methods for both simulated and actual magnetic resonance image data.

Luisier, Florian; Blu, Thierry; Wolfe, Patrick J.

2012-08-01

101

An Unbiased Cell Morphology-Based Screen for New, Biologically Active Small Molecules  

PubMed Central

We have implemented an unbiased cell morphology–based screen to identify small-molecule modulators of cellular processes using the Cytometrix (TM) automated imaging and analysis system. This assay format provides unbiased analysis of morphological effects induced by small molecules by capturing phenotypic readouts of most known classes of pharmacological agents and has the potential to read out pathways for which little is known. Four human-cancer cell lines and one noncancerous primary cell type were treated with 107 small molecules comprising four different protein kinase–inhibitor scaffolds. Cellular phenotypes induced by each compound were quantified by multivariate statistical analysis of the morphology, staining intensity, and spatial attributes of the cellular nuclei, microtubules, and Golgi compartments. Principal component analysis was used to identify inhibitors of cellular components not targeted by known protein kinase inhibitors. Here we focus on a hydroxyl-substituted analog (hydroxy-PP) of the known Src-family kinase inhibitor PP2 because it induced cell-specific morphological features distinct from all known kinase inhibitors in the collection. We used affinity purification to identify a target of hydroxy-PP, carbonyl reductase 1 (CBR1), a short-chain dehydrogenase-reductase. We solved the X-ray crystal structure of the CBR1/hydroxy-PP complex to 1.24 Å resolution. Structure-based design of more potent and selective CBR1 inhibitors provided probes for analyzing the biological function of CBR1 in A549 cells. These studies revealed a previously unknown function for CBR1 in serum-withdrawal-induced apoptosis. Further studies indicate CBR1 inhibitors may enhance the effectiveness of anticancer anthracyclines. Morphology-based screening of diverse cancer cell types has provided a method for discovering potent new small-molecule probes for cell biological studies and anticancer drug candidates.

2005-01-01

102

Testing assumptions for unbiased estimation of survival of radiomarked harlequin ducks  

USGS Publications Warehouse

Unbiased estimates of survival based on individuals outfitted with radiotransmitters require meeting the assumptions that radios do not affect survival, and animals for which the radio signal is lost have the same survival probability as those for which fate is known. In most survival studies, researchers have made these assumptions without testing their validity. We tested these assumptions by comparing interannual recapture rates (and, by inference, survival) between radioed and unradioed adult female harlequin ducks (Histrionicus histrionicus), and for radioed females, between right-censored birds (i.e., those for which the radio signal was lost during the telemetry monitoring period) and birds with known fates. We found that recapture rates of birds equipped with implanted radiotransmitters (21.6 ?? 3.0%; x?? ?? SE) were similar to unradioed birds (21.7 ?? 8.6%), suggesting that radios did not affect survival. Recapture rates also were similar between right-censored (20.6 ?? 5.1%) and known-fate individuals (22.1 ?? 3.8%), suggesting that missing birds were not subject to differential mortality. We also determined that capture and handling resulted in short-term loss of body mass for both radioed and unradioed females and that this effect was more pronounced for radioed birds (the difference between groups was 15.4 ?? 7.1 g). However, no difference existed in body mass after recapture 1 year later. Our study suggests that implanted radios are an unbiased method for estimating survival of harlequin ducks and likely other species under similar circumstances.

Esler, D.; Mulcahy, D. M.; Jarvis, R. L.

2000-01-01

103

Ultraviolet Spectra of the Complete 12Micron Seyfert 1 Galaxy Sample  

Microsoft Academic Search

We propose to obtain the first SWP spectra of UGC 5101, NGC 3511, and NGC 4602, to complete the coverage of the 121Lm Seyfert I galaxy sample. 12 micron selection provides the best unbiased bolometric flux-limited sample of AGNs (Spinoglio and Malkan 1989). We will also observe MKN 334, completing the SWP coverage of the optically-selected CfA Seyfert is, for

Matthew A. Malkan

1992-01-01

104

Spectra Optia Apheresis System  

Center for Biologics Evaluation and Research (CBER)

... Spectra Optia Apheresis System. Applicant: Terumo BCT, Inc. 510(k) number: BK120076. Product: Spectra Optia® Apheresis System. ... More results from www.fda.gov/biologicsbloodvaccines/bloodbloodproducts/approvedproducts

105

Optimum Time Step and Memory for GPS-based Unbiased FIR Estimates of the Local Clock TIE Model  

Microsoft Academic Search

In this paper, we address a theoretical analysis of errors of the l-degree unbiased finite impulse response (FIR) filter applied to the if-degree time interval error (TIE) model of a local clock. Emphasizing the fact that the TIE model originates from the slowly changing Brownian phase and thus cannot obligatorily be distinct on a horizon of N points, we investigate

Yuriy S. Shmaliy; Jorge Munoz-Diaz; Luis Arceo-Miquel; Oscar Ibarra-Manzano

2007-01-01

106

Empirical best linear unbiased prediction in misspecified and improved panel data models with an application to gasoline demand  

Microsoft Academic Search

Misspecifications in econometric models can result in misestimated coefficients. An improved method for specifying econometric models is presented. The mean square error of an empirical best linear unbiased predictor of an individual drawing for the dependent variable of an improved model is derived. These ideas are illustrated using certain misspecified and improved models of the demand for gasoline in the

P. A. V. B. Swamy; Wisam Yaghi; Jatinder S. Mehta; I-lok Chang

2007-01-01

107

Effects of corticosterone treatment and rehabilitation on the hippocampal formation of neonatal and adult rats. An unbiased stereological study  

Microsoft Academic Search

Elevations in the plasma levels of glucocorticoids are associated with cognitive impairments that have been ascribed to loss of neurons in the hippocampal formation. However, recent studies have strongly challenged this view. In order to clarify this issue, we have employed for the first time the optical fractionator and the Cavalieri principle, two unbiased stereological tools, to estimate respectively the

Nuno Sousa; Maria Dulce Madeira; Manuel M Paula-Barbosa

1998-01-01

108

Block-circulant matrices with circulant blocks, Weil sums, and mutually unbiased bases. II. The prime power case  

NASA Astrophysics Data System (ADS)

In our previous paper [Combescure, M., ``Circulant matrices, Gauss sums and the mutually unbiased bases. I. The prime number case,'' Cubo A Mathematical Journal (unpublished)] we have shown that the theory of circulant matrices allows to recover the result that there exists p+1 mutually unbiased bases in dimension p, p being an arbitrary prime number. Two orthonormal bases , ' of Cd are said mutually unbiased if ?b?, ?b'?' one has that |b.b'|=1/d (b.b' Hermitian scalar product in Cd). In this paper we show that the theory of block-circulant matrices with circulant blocks allows to show very simply the known result that if d=pn (p a prime number and n any integer) there exists d+1 mutually unbiased bases in Cd. Our result relies heavily on an idea of Klimov et al. [``Geometrical approach to the discrete Wigner function,'' J. Phys. A 39, 14471 (2006)]. As a subproduct we recover properties of quadratic Weil sums for p>=3, which generalizes the fact that in the prime case the quadratic Gauss sum properties follow from our results.

Combescure, Monique

2009-03-01

109

Aldehyde-selective wacker-type oxidation of unbiased alkenes enabled by a nitrite co-catalyst.  

PubMed

Breaking the rules: Reversal of the high Markovnikov selectivity of Wacker-type oxidations was accomplished using a nitrite co-catalyst. Unbiased aliphatic alkenes can be oxidized with high yield and aldehyde selectivity, and several functional groups are tolerated. (18) O-labeling experiments indicate that the aldehydic O?atom is derived from the nitrite salt. PMID:24039135

Wickens, Zachary K; Morandi, Bill; Grubbs, Robert H

2013-09-13

110

Identification and quantification of peptides and proteins secreted from prostate epithelial cells by unbiased liquid chromatography tandem mass spectrometry using goodness of fit and analysis of variance.  

PubMed

The proteins secreted by prostate cancer cells (PC3(AR)6) were separated by strong anion exchange chromatography, digested with trypsin and analyzed by unbiased liquid chromatography tandem mass spectrometry with an ion trap. The spectra were matched to peptides within proteins using a goodness of fit algorithm that showed a low false positive rate. The parent ions for MS/MS were randomly and independently sampled from a log-normal population and therefore could be analyzed by ANOVA. Normal distribution analysis confirmed that the parent and fragment ion intensity distributions were sampled over 99.9% of their range that was above the background noise. Arranging the ion intensity data with the identified peptide and protein sequences in structured query language (SQL) permitted the quantification of ion intensity across treatments, proteins and peptides. The intensity of 101,905 fragment ions from 1421 peptide precursors of 583 peptides from 233 proteins separated over 11 sample treatments were computed together in one ANOVA model using the statistical analysis system (SAS) prior to Tukey-Kramer honestly significant difference (HSD) testing. Thus complex mixtures of proteins were identified and quantified with a high degree of confidence using an ion trap without isotopic labels, multivariate analysis or comparing chromatographic retention times. PMID:22120120

Florentinus, Angelica K; Bowden, Peter; Sardana, Girish; Diamandis, Eleftherios P; Marshall, John G

2011-11-15

111

Unbiased orbit determination for the next generation asteroid/comet surveys  

NASA Astrophysics Data System (ADS)

In the next generation surveys, the discovery of moving objects can be successful only if an observation strategy and the identification/orbit determination procedure are appropriate for the diverse apparent motions of the target sub-populations. The observations must accurately measure the displacement over a short interval of time; observations believed to belong to the same object have to be connected into tracklets. Information contained in tracklets is in most cases not sufficient to compute an orbit: two or more of them must be identified to provide an orbit. We have developed a method for recursive identification of tracklets allowing an unbiased orbit determination for all sub-populations and efficient enough to cope with the data flow expected from the next generation surveys. The success of the new algorithms can be easily measured only in a simulation, by consulting a posteriori some "ground truth".We present here the results of a simulation of the orbit determination for one month of operations of the future Pan-STARRS survey, based upon a Solar System Model with a downsized population of Main Belt asteroids and a full size populations of Trojans, NEO, Centaurs, Comets and TNO. The results indicate that the method already developed and tested to find identifications of NEO and Main Belt asteroids are directly applicable to Trojans. The more distant objects often require modified algorithms, fitting orbits with only 4 parameters in a coordinate system specially adapted to handle very short arcs of observations. These orbits are mostly used as intermediate results, allowing to find full solutions as more tracklets are identified.When the number density of detections is as large as expected from the next generation surveys, both joining observations into tracklets and identifying tracklets can produce some false results. The only reliable way to remove them is a procedure of tracklet/identification management. It compares the tracklets and the identifications with a complex logic, allowing to discard almost all the false tracklets and all the false identifications. However, the distant objects still present a challenge for orbit determination: they require three tracklets in separate nights. If this requirement is met we have found no problem in achieving an unbiased orbit determination for all populations. Further work will lead to more advanced simulations, in particular by introducing a realistic model for astrometric and photometric errors.

Milani, A.; Gronchi, G. F.; Kneževic, Z.; Sansaturio, M. E.; Arratia, O.; Denneau, L.; Grav, T.; Heasley, J.; Jedicke, R.; Kubica, J.

112

Regulation of kidney development by Shp2: An unbiased stereological analysis  

PubMed Central

Genes that regulate renal branching morphogenesis are likely to indirectly regulate nephron endowment, but few have been validated to do so in vivo. PTPN11, which encodes the nonreceptor protein tyrosine phosphatase Shp2, acts downstream of receptor tyrosine kinases to modulate the Ras-MAPK pathway and has been implicated in branching morphogenesis in vitro and in invertebrates, and is therefore a candidate in vivo regulator of nephron number. In this work, heterozygous null mutant Shp2+/? mice at postnatal days 30–35 were compared with their wild-type (WT) littermates using unbiased stereology to determine if, indeed, the former had decreased nephron number due to their 50% decrease in gene/protein dosage. Although there was a trend toward decreases in total glomerular (nephron) number and kidney volume in Shp2+/? mice compared with WT, neither difference was statistically significant (11310 vs. 12198 glomeruli, p=0.22; 62.8 mm3 vs. 66.0 mm3 renal volume; p=0.40). We conclude that loss of 50% gene/protein dosage of PTPN11/Shp2 is insufficient to affect glomerular (and thereby nephron) number in mouse kidneys in vivo.

David, Frank S.; Cullen-McEwen, Luise; Wu, Xue Sue; Zins, Stephen R.; Lin, Julie; Bertram, John F.; Neel, Benjamin G.

2010-01-01

113

Mutually orthogonal Latin squares from the inner products of vectors in mutually unbiased bases  

NASA Astrophysics Data System (ADS)

Mutually unbiased bases (MUBs) are important in quantum information theory. While constructions of complete sets of d + 1 MUBs in {\\bb C}^d are known when d is a prime power, it is unknown if such complete sets exist in non-prime power dimensions. It has been conjectured that complete sets of MUBs only exist in {\\bb C}^d if a maximal set of mutually orthogonal Latin squares (MOLS) of side length d also exists. There are several constructions (Roy and Scott 2007 J. Math. Phys. 48 072110; Paterek, Daki? and Brukner 2009 Phys. Rev. A 79 012109) of complete sets of MUBs from specific types of MOLS, which use Galois fields to construct the vectors of the MUBs. In this paper, two known constructions of MUBs (Alltop 1980 IEEE Trans. Inf. Theory 26 350-354 Wootters and Fields 1989 Ann. Phys. 191 363-381), both of which use polynomials over a Galois field, are used to construct complete sets of MOLS in the odd prime case. The MOLS come from the inner products of pairs of vectors in the MUBs.

Hall, Joanne L.; Rao, Asha

2010-04-01

114

How unbiased is non-targeted metabolomics and is targeted pathway screening the solution?  

PubMed

Metabolomics is only truly unbiased if the whole metabolome is captured. Current metabolomics technologies capture only a part of the metabolome and therefore produce inherently biased results. Important factors that introduce such bias into a metabolomic analysis may include but are not limited to, timing of sample collection, the sample collection procedure, sample processing, stabilization, stability and storage, extraction procedures, dilution of sample, type and number of analytical methods used, preferences of analytical assays for metabolites with certain physico-chemical properties, ion suppression (LC-MS), derivatization (GC-MS), sensitivity of the assay, range of reliable response and the ability to allow at least for semi-quantitative comparison. Consideration of the many computational, chemometric and biostatistical steps required to link changes in metabolite patterns to metabolic pathways and the additional bias and risks that these steps entail, brings up the question of whether or not screening for changes in known metabolic pathways using a set of validated, quantitative multiplexing LC-MS assays (targeted pathway screening, TAPAS) would be a more robust and reliable approach. Instead of non-selectively screening for changes in metabolite patterns, TAPAS screens for changes in metabolic pathways. Since such assays are designed for specific groups of metabolites, TAPAS can cover a larger number of metabolic pathways including metabolites of a wide variety of physicochemical properties and concentration ranges and thus, although based on suite of targeted assays, TAPAS may ultimately be a less biased strategy than current non-targeted metabolomics technologies. PMID:21466457

Christians, Uwe; Klawitter, Jelena; Hornberger, Andrea; Klawitter, Jost

2011-07-01

115

Intramolecular Hydroamination of Unbiased and Functionalized Primary Aminoalkenes Catalyzed by a Rhodium Aminophosphine Complex  

PubMed Central

We report a rhodium catalyst that exhibits high reactivity for the hydroamination of primary aminoalkenes that are unbiased toward cyclization and that possess functional groups that would not be tolerated in hydroaminations catalyzed by more electrophilic systems. This catalyst contains an unusual diaminophosphine ligand that binds to rhodium in a ?3-P,O,P mode. The reactions catalyzed by this complex typically proceed at mild temperatures (room temperature to 70 °C), occur with primary aminoalkenes lacking substituents on the alkyl chain that bias the system toward cyclization, occur with primary aminoalkenes containing chloride, ester, ether, enolizable ketone, nitrile, and unprotected alcohol functionality, and occur with primary aminoalkenes containing internal olefins. Mechanistic data imply that these reactions occur with a turnover-limiting step that is different from that of reactions catalyzed by late transition metal complexes of Pd, Pt, and Ir. This change in the turnover-limiting step and resulting high activity of the catalyst stem from favorable relative rates for protonolysis of the M-C bond to release the hydroamination product vs reversion of the aminoalkyl intermediate to regenerate the acyclic precursor. Probes for the origin of the reactivity of the rhodium complex of L1 imply that the aminophosphine groups lead to these favorable rates by effects beyond steric demands and simple electron donation to the metal center.

Julian, Lisa D.; Hartwig, John F.

2010-01-01

116

Unbiased Discovery of Glypican as a Receptor for LRRTM4 in Regulating Excitatory Synapse Development.  

PubMed

Leucine-rich repeat (LRR) proteins have recently been identified as important regulators of synapse development and function, but for many LRR proteins the ligand-receptor interactions are not known. Here we identify the heparan sulfate (HS) proteoglycan glypican as a receptor for LRRTM4 using an unbiased proteomics-based approach. Glypican binds LRRTM4, but not LRRTM2, in an HS-dependent manner. Glypican 4 (GPC4) and LRRTM4 localize to the pre- and postsynaptic membranes of excitatory synapses, respectively. Consistent with a trans-synaptic interaction, LRRTM4 triggers GPC4 clustering in contacting axons and GPC4 induces clustering of LRRTM4 in contacting dendrites in an HS-dependent manner. LRRTM4 positively regulates excitatory synapse development in cultured neurons and in vivo, and the synaptogenic activity of LRRTM4 requires the presence of HS on the neuronal surface. Our results identify glypican as an LRRTM4 receptor and indicate that a trans-synaptic glypican-LRRTM4 interaction regulates excitatory synapse development. PMID:23911103

de Wit, Joris; O'Sullivan, Matthew L; Savas, Jeffrey N; Condomitti, Giuseppe; Caccese, Max C; Vennekens, Kristel M; Yates, John R; Ghosh, Anirvan

2013-08-01

117

Toward Unbiased Galaxy Cluster Masses from Line-of-sight Velocity Dispersions  

NASA Astrophysics Data System (ADS)

We study the use of red-sequence-selected galaxy spectroscopy for unbiased estimation of galaxy cluster masses by using a publicly available simulated galaxy catalog. We explore the impact of selection using galaxy color, projected separation from the cluster center, galaxy luminosity, and spectroscopic redshift. We identify and characterize each of the following sources of bias and scatter in velocity dispersion at fixed mass: the intrinsic properties of halos in the form of halo triaxiality, sampling noise, the presence of multiple kinematic populations within the cluster, and the effect of interlopers. We show that even in red-sequence and spectroscopically selected galaxy samples, the interloper fraction is significant, and that the variations in the interloper population from cluster to cluster provide the dominant contribution to the velocity dispersion scatter at fixed mass. We present measurements of the total scatter in dispersion at fixed mass as a function of the number of redshifts. Results indicate that improvements in scatter are modest beyond samples of ~30 redshifts per cluster. Our results show that while cluster velocity dispersions extracted from a few dozen red-sequence-selected galaxies do not provide precise masses on a single cluster basis, an ensemble of cluster velocity dispersions can be combined to produce a precise calibration of a cluster survey-mass-observable relation. Currently, disagreements in the literature on simulated subhalo velocity dispersion-mass relations place a systematic floor on velocity dispersion mass calibration at the 5% level in dispersion.

Saro, Alex; Mohr, Joseph J.; Bazin, Gurvan; Dolag, Klaus

2013-07-01

118

Science with SIRIUS: Simultaneous-color InfraRed Imager for Unbiased Surveys  

NASA Astrophysics Data System (ADS)

Some results from the near infrared camera SIRIUS are presented. SIRIUS is designed for deep and wide JHKs-bands simultaneous surveys, being equipped with three science-grade HAWAII (1024×1024) arrays. SIRIUS is attached on a dedicated 1.4m telescope (IRSF) at Sutherland observatory in South Africa. The field of view is 7.8'×7.8', the pixel scale is 0.45", and the limiting magnitude is J=19.2, H=18.6, Ks=17.3 (S/N=10? and 15minutes integration) with the 1.4m telescope. The survey of southern sky began in November 2000. SIRIUS was also used on the University of Hawaii 2.2m telescope at Mauna Kea for three times in August 2000, October 2000, and September 2001. Surveys of several northern sky areas were done. Unbiased deep survey for 6 degree square area of Large Magellanic Cloud (LMC) is one of the key programs with the 1.4m telescope. Several clusters of intermediate mass YSO candidates have been discovered so far. Monitoring surveys of several selected areas of LMC have also been carried out for detection of variable stars. The other main science programs of SIRIUS are deep imaging surveys of star forming regions in our galaxy, brown dwarf surveys in clusters, search for galaxies behind the Milky way (the Zone of Avoidance), and surveys toward the galactic center.

Nakajima, Yasushi; Tamura, Motohide; Nagashima, Chie; Nagayama, Takahiro; Baba, Daisuke; Sugitani, Koji; Nakaya, Hidehiko; Nagata, Tetsuya; Kato, Daisuke; Kurita, Mikio; Sato, Shuji; Jiang, Zhibo; Ita, Yoshifusa; Tanabe, Toshihiko; Nakata, Yoshikazu; Naoi, Takashi; Oasa, Yumiko

2002-12-01

119

Estimating time-correlation functions by sampling and unbiasing dynamically activated events  

NASA Astrophysics Data System (ADS)

Transition path sampling is a rare-event method that estimates state-to-state time-correlation functions in many-body systems from samples of short trajectories. In this framework, it is proposed to bias the importance function using the lowest Jacobian eigenvalue moduli along the dynamical trajectory. A lowest eigenvalue modulus is related to the lowest eigenvalue of the Hessian matrix and is evaluated here using the Lanczos algorithm as in activation-relaxation techniques. This results in favoring the sampling of activated trajectories and enhancing the occurrence of the rare reactive trajectories of interest, those corresponding to transitions between locally stable states. Estimating the time-correlation functions involves unbiasing the sample of simulated trajectories which is done using the multi-state Bennett acceptance ratio (MBAR) method. To assess the performance of our procedure, we compute the time-correlation function associated with the migration of a vacancy in ?-iron. The derivative of the estimated time-correlation function yields a migration rate in agreement with the one given by transition state theory. Besides, we show that the information relative to rejected trajectories can be recycled within MBAR, resulting in a substantial speed-up. Unlike original transition path-sampling, our approach does not require computing the reversible work to confine the trajectory endpoints to a reactive state.

Athènes, Manuel; Marinica, Mihai-Cosmin; Jourdan, Thomas

2012-11-01

120

Unbiased Resource Evaluations with Kriging and Stochastic Models of Heterogeneous Rock Properties  

SciTech Connect

This paper revisits the computation of product combinations for quantification of resources (e.g., pore volume for hydrocarbon reservoir formations). The explanations have been simplified by considering the exhaustive numerical model for properties that are multiplied first and then added or averaged for evaluation. The analysis starts without any probabilistic considerations. Abbreviated (up-scaled) computations in the sum of multiplications are proposed by substituting the individual values by averages for each rock property in the coarser cell resolution model. A result found is that averaged properties can be utilized for estimation at non-sampled locations, instead of individual values; however, covariances and cumulants must also be included in the abbreviated computations. The smoothing effect of kriging is found to be irrelevant if the kriging variance is also included in the up-scaled abbreviated pore volume computations. Thus, the equivalence between computation of resource volumes from kriging estimates and conditional stochastic simulations is established, with the condition that numerical estimation must incorporate the complete covariance and cumulant information as well. An example shows pore volume prediction from a kriging model matches the unbiased result from stochastic simulations.

Vargas-Guzman, J.A., E-mail: anton_varguz@hotmail.com

2008-12-15

121

Unbiased simultaneous estimation of soil hydraulic properties and dynamic nonequilibrium parameters from transient outflow experiments  

NASA Astrophysics Data System (ADS)

Simulation of variably saturated water flow in soils requires accurate knowledge of soil hydraulic properties. Transient flow experiments like the multistep outflow and evaporation methods are now routinely applied to determine soil hydraulic parameters by inverse modelling. Recent experimental evidence suggests that the water content dynamics during such flow experiments is subject to dynamic non-equilibrium. The extent to which this affects the accuracy of determining the equilibrium soil hydraulic properties is still unknown. Conversely, any bias in the equilibrium soil hydraulic properties caused by an inappropriate parameterization must be expected to lead to biased estimates of the parameters describing the hydraulic non-equilibrium. We coupled a dual porosity non-equilibrium model which combines the Richards equation and the Ross and Smettem approach for non-equilibrium with a free-form inversion algorithm. The free-form method has been shown before to guarantee an unbiased estimation of soil hydraulic properties. The freeform non-equilibrium estimation method was applied to data from various multistep outflow experiments. The results confirm that errors in the parameterization of the soil hydraulic properties cause biased estimates of non-equilibrium parameters. Such bias can be minimized or even eliminated with the free-form approach.

Iden, S. C.; Diamantopoulos, E.; Durner, W.

2012-04-01

122

Development of an unbiased statistical method for the analysis of unigenic evolution  

PubMed Central

Background Unigenic evolution is a powerful genetic strategy involving random mutagenesis of a single gene product to delineate functionally important domains of a protein. This method involves selection of variants of the protein which retain function, followed by statistical analysis comparing expected and observed mutation frequencies of each residue. Resultant mutability indices for each residue are averaged across a specified window of codons to identify hypomutable regions of the protein. As originally described, the effect of changes to the length of this averaging window was not fully eludicated. In addition, it was unclear when sufficient functional variants had been examined to conclude that residues conserved in all variants have important functional roles. Results We demonstrate that the length of averaging window dramatically affects identification of individual hypomutable regions and delineation of region boundaries. Accordingly, we devised a region-independent chi-square analysis that eliminates loss of information incurred during window averaging and removes the arbitrary assignment of window length. We also present a method to estimate the probability that conserved residues have not been mutated simply by chance. In addition, we describe an improved estimation of the expected mutation frequency. Conclusion Overall, these methods significantly extend the analysis of unigenic evolution data over existing methods to allow comprehensive, unbiased identification of domains and possibly even individual residues that are essential for protein function.

Behrsin, Colleen D; Brandl, Chris J; Litchfield, David W; Shilton, Brian H; Wahl, Lindi M

2006-01-01

123

Unbiased Mapping of Transcription Factor Binding Sites along Human Chromosomes 21 and 22 Points to Widespread Regulation of Noncoding RNAs  

Microsoft Academic Search

Using high-density oligonucleotide arrays representing essentially all nonrepetitive sequences on human chromosomes 21 and 22, we map the binding sites in vivo for three DNA binding transcription factors, Sp1, cMyc, and p53, in an unbiased manner. This mapping reveals an unexpectedly large number of transcription factor binding site (TFBS) regions, with a minimal estimate of 12,000 for Sp1, 25,000 for

Simon Cawley; Stefan Bekiranov; Huck H. Ng; Philipp Kapranov; Edward A. Sekinger; Dione Kampa; Antonio Piccolboni; Victor Sementchenko; Jill Cheng; Alan J. Williams; Raymond Wheeler; Brant Wong; Jorg Drenkow; Mark Yamanaka; Sandeep Patel; Shane Brubaker; Hari Tammana; Gregg Helt; Kevin Struhl; Thomas R Gingeras

2004-01-01

124

Finalizing host range determination of a weed biological control pathogen with best linear unbiased predictors and damage assessment  

Microsoft Academic Search

Colletotrichum gloeosporioides f. sp. salsolae (Penz.) Penz. & Sacc. in Penz. (CGS) is a facultative parasitic fungus being evaluated as a classical biological control\\u000a agent of Russian thistle or tumbleweed (Salsola tragus L.). In initial host range determination tests, Henderson’s mixed model equations (MME) were used to generate best linear\\u000a unbiased predictors (BLUPs) of disease severity reaction to CGS among

Dana K. BernerCraig; Craig A. Cavin

125

An unbiased approach to identifying tau kinases that phosphorylate tau at sites associated with Alzheimer disease.  

PubMed

Neurofibrillary tangles, one of the hallmarks of Alzheimer disease (AD), are composed of paired helical filaments of abnormally hyperphosphorylated tau. The accumulation of these proteinaceous aggregates in AD correlates with synaptic loss and severity of dementia. Identifying the kinases involved in the pathological phosphorylation of tau may identify novel targets for AD. We used an unbiased approach to study the effect of 352 human kinases on their ability to phosphorylate tau at epitopes associated with AD. The kinases were overexpressed together with the longest form of human tau in human neuroblastoma cells. Levels of total and phosphorylated tau (epitopes Ser(P)-202, Thr(P)-231, Ser(P)-235, and Ser(P)-396/404) were measured in cell lysates using AlphaScreen assays. GSK3?, GSK3?, and MAPK13 were found to be the most active tau kinases, phosphorylating tau at all four epitopes. We further dissected the effects of GSK3? and GSK3? using pharmacological and genetic tools in hTau primary cortical neurons. Pathway analysis of the kinases identified in the screen suggested mechanisms for regulation of total tau levels and tau phosphorylation; for example, kinases that affect total tau levels do so by inhibition or activation of translation. A network fishing approach with the kinase hits identified other key molecules putatively involved in tau phosphorylation pathways, including the G-protein signaling through the Ras family of GTPases (MAPK family) pathway. The findings identify novel tau kinases and novel pathways that may be relevant for AD and other tauopathies. PMID:23798682

Cavallini, Annalisa; Brewerton, Suzanne; Bell, Amanda; Sargent, Samantha; Glover, Sarah; Hardy, Clare; Moore, Roger; Calley, John; Ramachandran, Devaki; Poidinger, Michael; Karran, Eric; Davies, Peter; Hutton, Michael; Szekeres, Philip; Bose, Suchira

2013-06-24

126

An unbiased assessment of the role of imprinted genes in an intergenerational model of developmental programming.  

PubMed

Environmental factors during early life are critical for the later metabolic health of the individual and of future progeny. In our obesogenic environment, it is of great socioeconomic importance to investigate the mechanisms that contribute to the risk of metabolic ill health. Imprinted genes, a class of functionally mono-allelic genes critical for early growth and metabolic axis development, have been proposed to be uniquely susceptible to environmental change. Furthermore, it has also been suggested that perturbation of the epigenetic reprogramming of imprinting control regions (ICRs) may play a role in phenotypic heritability following early life insults. Alternatively, the presence of multiple layers of epigenetic regulation may in fact protect imprinted genes from such perturbation. Unbiased investigation of these alternative hypotheses requires assessment of imprinted gene expression in the context of the response of the whole transcriptome to environmental assault. We therefore analyse the role of imprinted genes in multiple tissues in two affected generations of an established murine model of the developmental origins of health and disease using microarrays and quantitative RT-PCR. We demonstrate that, despite the functional mono-allelicism of imprinted genes and their unique mechanisms of epigenetic dosage control, imprinted genes as a class are neither more susceptible nor protected from expression perturbation induced by maternal undernutrition in either the F1 or the F2 generation compared to other genes. Nor do we find any evidence that the epigenetic reprogramming of ICRs in the germline is susceptible to nutritional restriction. However, we propose that those imprinted genes that are affected may play important roles in the foetal response to undernutrition and potentially its long-term sequelae. We suggest that recently described instances of dosage regulation by relaxation of imprinting are rare and likely to be highly regulated. PMID:22511876

Radford, Elizabeth J; Isganaitis, Elvira; Jimenez-Chillaron, Josep; Schroeder, Joshua; Molla, Michael; Andrews, Simon; Didier, Nathalie; Charalambous, Marika; McEwen, Kirsten; Marazzi, Giovanna; Sassoon, David; Patti, Mary-Elizabeth; Ferguson-Smith, Anne C

2012-04-12

127

An Unbiased Assessment of the Role of Imprinted Genes in an Intergenerational Model of Developmental Programming  

PubMed Central

Environmental factors during early life are critical for the later metabolic health of the individual and of future progeny. In our obesogenic environment, it is of great socioeconomic importance to investigate the mechanisms that contribute to the risk of metabolic ill health. Imprinted genes, a class of functionally mono-allelic genes critical for early growth and metabolic axis development, have been proposed to be uniquely susceptible to environmental change. Furthermore, it has also been suggested that perturbation of the epigenetic reprogramming of imprinting control regions (ICRs) may play a role in phenotypic heritability following early life insults. Alternatively, the presence of multiple layers of epigenetic regulation may in fact protect imprinted genes from such perturbation. Unbiased investigation of these alternative hypotheses requires assessment of imprinted gene expression in the context of the response of the whole transcriptome to environmental assault. We therefore analyse the role of imprinted genes in multiple tissues in two affected generations of an established murine model of the developmental origins of health and disease using microarrays and quantitative RT–PCR. We demonstrate that, despite the functional mono-allelicism of imprinted genes and their unique mechanisms of epigenetic dosage control, imprinted genes as a class are neither more susceptible nor protected from expression perturbation induced by maternal undernutrition in either the F1 or the F2 generation compared to other genes. Nor do we find any evidence that the epigenetic reprogramming of ICRs in the germline is susceptible to nutritional restriction. However, we propose that those imprinted genes that are affected may play important roles in the foetal response to undernutrition and potentially its long-term sequelae. We suggest that recently described instances of dosage regulation by relaxation of imprinting are rare and likely to be highly regulated.

Radford, Elizabeth J.; Isganaitis, Elvira; Jimenez-Chillaron, Josep; Schroeder, Joshua; Molla, Michael; Andrews, Simon; Didier, Nathalie; Charalambous, Marika; McEwen, Kirsten; Marazzi, Giovanna; Sassoon, David; Patti, Mary-Elizabeth; Ferguson-Smith, Anne C.

2012-01-01

128

An anatomically unbiased approach for analysis of renal BOLD magnetic resonance images.  

PubMed

Oxygenation defects may contribute to renal disease progression, but the chronology of events is difficult to define in vivo without recourse to invasive methodologies. Blood oxygen level-dependent magnetic resonance imaging (BOLD MRI) provides an attractive alternative, but the R2* signal is physiologically complex. Postacquisition data analysis often relies on manual selection of region(s) of interest. This approach excludes from analysis significant quantities of biological information and is subject to selection bias. We present a semiautomated, anatomically unbiased approach to compartmentalize voxels into two quantitatively related clusters. In control F344 rats, low R2* clustering was located predominantly within the cortex and higher R2* clustering within the medulla (70.96 ± 1.48 vs. 79.00 ± 1.50; 3 scans per rat; n = 6; P < 0.01) consistent anatomically with a cortico-medullary oxygen gradient. An intravenous bolus of acetylcholine caused a transient reduction of the R2* signal in both clustered segments (P < 0.01). This was nitric oxide dependent and temporally distinct from the hemodynamic effects of acetylcholine. Rats were then chronically infused with angiotensin II (60 ng/min) and rescanned 3 days later. Clustering demonstrated a disruption of the cortico-medullary gradient, producing less distinctly segmented mean R2* clusters (71.30 ± 2.00 vs. 72.48 ± 1.27; n = 6; NS). The acetylcholine-induced attenuation of the R2* signal was abolished by chronic angiotensin II infusion, consistent with reduced nitric oxide bioavailability. This global map of oxygenation, defined by clustering individual voxels on the basis of quantitative nearness, might be more robust in defining deficits in renal oxygenation than the absolute magnitude of R2* in small, manually selected regions of interest defined exclusively by anatomical nearness. PMID:23863466

Menzies, Robert I; Zammit-Mangion, Andrew; Hollis, Lyam M; Lennen, Ross J; Jansen, Maurits A; Webb, David J; Mullins, John J; Dear, James W; Sanguinetti, Guido; Bailey, Matthew A

2013-07-17

129

Predicting Genetic Values: A Kernel-Based Best Linear Unbiased Prediction With Genomic Data  

PubMed Central

Genomic data provide a valuable source of information for modeling covariance structures, allowing a more accurate prediction of total genetic values (GVs). We apply the kriging concept, originally developed in the geostatistical context for predictions in the low-dimensional space, to the high-dimensional space spanned by genomic single nucleotide polymorphism (SNP) vectors and study its properties in different gene-action scenarios. Two different kriging methods [“universal kriging” (UK) and “simple kriging” (SK)] are presented. As a novelty, we suggest use of the family of Matérn covariance functions to model the covariance structure of SNP vectors. A genomic best linear unbiased prediction (GBLUP) is applied as a reference method. The three approaches are compared in a whole-genome simulation study considering additive, additive-dominance, and epistatic gene-action models. Predictive performance is measured in terms of correlation between true and predicted GVs and average true GVs of the individuals ranked best by prediction. We show that UK outperforms GBLUP in the presence of dominance and epistatic effects. In a limiting case, it is shown that the genomic covariance structure proposed by VanRaden (2008) can be considered as a covariance function with corresponding quadratic variogram. We also prove theoretically that if a specific linear relationship exists between covariance matrices for two linear mixed models, the GVs resulting from BLUP are linked by a scaling factor. Finally, the relation of kriging to other models is discussed and further options for modeling the covariance structure, which might be more appropriate in the genomic context, are suggested.

Ober, Ulrike; Erbe, Malena; Long, Nanye; Porcu, Emilio; Schlather, Martin; Simianer, Henner

2011-01-01

130

Prediction of complex human traits using the genomic best linear unbiased predictor.  

PubMed

Despite important advances from Genome Wide Association Studies (GWAS), for most complex human traits and diseases, a sizable proportion of genetic variance remains unexplained and prediction accuracy (PA) is usually low. Evidence suggests that PA can be improved using Whole-Genome Regression (WGR) models where phenotypes are regressed on hundreds of thousands of variants simultaneously. The Genomic Best Linear Unbiased Prediction (G-BLUP, a ridge-regression type method) is a commonly used WGR method and has shown good predictive performance when applied to plant and animal breeding populations. However, breeding and human populations differ greatly in a number of factors that can affect the predictive performance of G-BLUP. Using theory, simulations, and real data analysis, we study the performance of G-BLUP when applied to data from related and unrelated human subjects. Under perfect linkage disequilibrium (LD) between markers and QTL, the prediction R-squared (R(2)) of G-BLUP reaches trait-heritability, asymptotically. However, under imperfect LD between markers and QTL, prediction R(2) based on G-BLUP has a much lower upper bound. We show that the minimum decrease in prediction accuracy caused by imperfect LD between markers and QTL is given by (1-b)(2), where b is the regression of marker-derived genomic relationships on those realized at causal loci. For pairs of related individuals, due to within-family disequilibrium, the patterns of realized genomic similarity are similar across the genome; therefore b is close to one inducing small decrease in R(2). However, with distantly related individuals b reaches very low values imposing a very low upper bound on prediction R(2). Our simulations suggest that for the analysis of data from unrelated individuals, the asymptotic upper bound on R(2) may be of the order of 20% of the trait heritability. We show how PA can be enhanced with use of variable selection or differential shrinkage of estimates of marker effects. PMID:23874214

de Los Campos, Gustavo; Vazquez, Ana I; Fernando, Rohan; Klimentidis, Yann C; Sorensen, Daniel

2013-07-11

131

The unbiased measurement of ultraviolet spectral slopes in low-luminosity galaxies at z ? 7  

NASA Astrophysics Data System (ADS)

The ultraviolet (UV) continuum slope ?, typically observed at z ? 7 in Hubble Space Telescope (HST) WFC3/IR bands via the J - H colour, is a useful indicator of the age, metallicity and dust content of high-redshift stellar populations. Recent studies have shown that the redward evolution of ? with cosmic time from redshift 7 to 4 can be largely explained by a buildup of dust. However, initial claims that faint z ? 7 galaxies in the Hubble Ultra Deep Field WFC3/IR imaging (HUDF09) were blue enough to require stellar populations of zero reddening, low metallicity and young ages, hitherto unseen in star-forming galaxies, have since been refuted and revised. Here we revisit the question of how best to measure the UV slope of z ? 7 galaxies through source recovery simulations, within the context of present and future ultra-deep imaging from HST. We consider how source detection, selection and colour measurement have each biased the measurement of ? in previous studies. After finding a robust method for measuring ? in the simulations (via a power-law fit to all the available photometry), we remeasure the UV slopes of a sample of previously published low-luminosity z ? 7 galaxy candidates. The mean UV slope of faint galaxies in this sample appears consistent with an intrinsic distribution of normal star-forming galaxies with ? ? -2, although properly decoding the underlying distribution will require further imaging from the ongoing HUDF12 programme. We therefore go on to consider strategies for obtaining better constraints on the underlying distribution of UV slopes at z ? 7 from these new data, which will benefit particularly from the addition of imaging in a second J-band filter: F140W. We find that a precise and unbiased measurement of ? should then be possible.

Rogers, A. B.; McLure, R. J.; Dunlop, J. S.

2013-03-01

132

Unbiased Transcriptional Comparisons of Generalist and Specialist Herbivores Feeding on Progressively Defenseless Nicotiana attenuata Plants  

PubMed Central

Background Herbivore feeding elicits dramatic increases in defenses, most of which require jasmonate (JA) signaling, and against which specialist herbivores are thought to be better adapted than generalist herbivores. Unbiased transcriptional analyses of how neonate larvae cope with these induced plant defenses are lacking. Methodology/Principal Findings We created cDNA microarrays for Manduca sexta and Heliothis virescens separately, by spotting normalized midgut-specific cDNA libraries created from larvae that fed for 24 hours on MeJA-elicited wild-type (WT) Nicotiana attenuata plants. These microarrays were hybridized with labeled probes from neonates that fed for 24 hours on WT and isogenic plants progressively silenced in JA-mediated defenses (N: nicotine; N/PI: N and trypsin protease inhibitors; JA: all JA-mediated defenses). H. virescens neonates regulated 16 times more genes than did M. sexta neonates when they fed on plants silenced in JA-mediated defenses, and for both species, the greater the number of defenses silenced in the host plant (JA > N/PI > N), the greater were the number of transcripts regulated in the larvae. M. sexta larvae tended to down-regulate while H. virescens larvae up- and down-regulated transcripts from the same functional categories of genes. M. sexta larvae regulated transcripts in a diet-specific manner, while H. virescens larvae regulated a similar suite of transcripts across all diet types. Conclusions/Significance The observations are consistent with the expectation that specialists are better adapted than generalist herbivores to the defense responses elicited in their host plants by their feeding. While M. sexta larvae appear to be better adapted to N. attenuata's defenses, some of the elicited responses remain effective defenses against both herbivore species. The regulated genes provide novel insights into larval adaptations to N. attenuata's induced defenses, and represent potential targets for plant-mediated RNAi to falsify hypotheses about the process of adaptation.

Govind, Geetha; Mittapalli, Omprakash; Griebel, Thasso; Allmann, Silke; Bocker, Sebastian; Baldwin, Ian Thomas

2010-01-01

133

Unbiased Review of Digital Diagnostic Images in Practice: Informatics Prototype and Pilot Study  

PubMed Central

Rationale and Objectives Clinical and contextual information associated with images may influence how radiologists draw diagnostic inferences, highlighting the need to control multiple sources of bias in the methodological design of investigations involving radiological interpretation. In the past, manual control methods to mask review films presented in practice have been used to reduce potential interpretive bias associated with differences between viewing images for patient care versus reviewing images for purposes of research, education, and quality improvement. These manual precedents from the film era raise the question whether similar methods to reduce bias can be implemented in the modern digital environment. Materials and Methods We built prototype “CreateAPatient” information technology for masking review case presentations within our institution’s production Radiology Information and Picture Archiving and Reporting Systems (RIS and PACS). To test whether CreateAPatient could be used to mask review images presented in practice, six board-certified radiologists participated in a pilot study. During pilot testing, seven digital chest radiographs, known to contain lung nodules and associated with fictitious patient identifiers, were mixed into the routine workload of the participating radiologists while they covered general evening call shifts. We tested whether it was possible to mask the presentation of these review cases, both by probing the interpreting radiologists to report detection and by conducting a forced-choice experiment on a separate cohort of 20 radiologists and information technology professionals. Results None of the participating radiologists reported awareness of review activity, and forced-choice detection was less than predicted at chance, suggesting radiologists were effectively blinded. In addition, we identified no evidence of review reports unsafely propagating beyond their intended scope or otherwise interfering with patient care, despite integration of these records within production electronic workflow systems. Conclusion Information technology can facilitate the design of unbiased methods involving professional review of digital diagnostic images.

Fotenos, Anthony F.; Safdar, Nabile M.; Nagy, Paul G.; Mezrich, Reuben; Lewin, Jonathan S.

2013-01-01

134

Predicting genetic values: a kernel-based best linear unbiased prediction with genomic data.  

PubMed

Genomic data provide a valuable source of information for modeling covariance structures, allowing a more accurate prediction of total genetic values (GVs). We apply the kriging concept, originally developed in the geostatistical context for predictions in the low-dimensional space, to the high-dimensional space spanned by genomic single nucleotide polymorphism (SNP) vectors and study its properties in different gene-action scenarios. Two different kriging methods ["universal kriging" (UK) and "simple kriging" (SK)] are presented. As a novelty, we suggest use of the family of Matérn covariance functions to model the covariance structure of SNP vectors. A genomic best linear unbiased prediction (GBLUP) is applied as a reference method. The three approaches are compared in a whole-genome simulation study considering additive, additive-dominance, and epistatic gene-action models. Predictive performance is measured in terms of correlation between true and predicted GVs and average true GVs of the individuals ranked best by prediction. We show that UK outperforms GBLUP in the presence of dominance and epistatic effects. In a limiting case, it is shown that the genomic covariance structure proposed by VanRaden (2008) can be considered as a covariance function with corresponding quadratic variogram. We also prove theoretically that if a specific linear relationship exists between covariance matrices for two linear mixed models, the GVs resulting from BLUP are linked by a scaling factor. Finally, the relation of kriging to other models is discussed and further options for modeling the covariance structure, which might be more appropriate in the genomic context, are suggested. PMID:21515573

Ober, Ulrike; Erbe, Malena; Long, Nanye; Porcu, Emilio; Schlather, Martin; Simianer, Henner

2011-04-21

135

Unbiased Nearly Best Linear Estimates of the Scale and Location Parameters of the Extreme Value Distribution by the Use of Order Statistics.  

National Technical Information Service (NTIS)

Unbiased nearly best linear estimates of the scale and location parameters of the (first) extreme value distribution of largest values estimators were calculated and tabled for sample sizes from 15 to 40. The tables include coefficients of estimators for ...

K. E. Eickmann

1968-01-01

136

The Optically Unbiased Gamma-Ray Burst Host (TOUGH) Survey. I. Survey Design and Catalogs  

NASA Astrophysics Data System (ADS)

Long-duration gamma-ray bursts (GRBs) are powerful tracers of star-forming galaxies. We have defined a homogeneous subsample of 69 Swift GRB-selected galaxies spanning a very wide redshift range. Special attention has been devoted to making the sample optically unbiased through simple and well-defined selection criteria based on the high-energy properties of the bursts and their positions on the sky. Thanks to our extensive follow-up observations, this sample has now achieved a comparatively high degree of redshift completeness, and thus provides a legacy sample, useful for statistical studies of GRBs and their host galaxies. In this paper, we present the survey design and summarize the results of our observing program conducted at the ESO Very Large Telescope (VLT) aimed at obtaining the most basic properties of galaxies in this sample, including a catalog of R and Ks magnitudes and redshifts. We detect the host galaxies for 80% of the GRBs in the sample, although only 42% have Ks -band detections, which confirms that GRB-selected host galaxies are generally blue. The sample is not uniformly blue, however, with two extremely red objects detected. Moreover, galaxies hosting GRBs with no optical/NIR afterglows, whose identification therefore relies on X-ray localizations, are significantly brighter and redder than those with an optical/NIR afterglow. This supports a scenario where GRBs occurring in more massive and dusty galaxies frequently suffer high optical obscuration. Our spectroscopic campaign has resulted in 77% now having redshift measurements, with a median redshift of 2.14 ± 0.18. TOUGH alone includes 17 detected z > 2 Swift GRB host galaxies suitable for individual and statistical studies—a substantial increase over previous samples. Seven hosts have detections of the Ly? emission line and we can exclude an early indication that Ly? emission is ubiquitous among GRB hosts, but confirm that Ly? is stronger in GRB-selected galaxies than in flux-limited samples of Lyman break galaxies. .

Hjorth, Jens; Malesani, Daniele; Jakobsson, Páll; Jaunsen, Andreas O.; Fynbo, Johan P. U.; Gorosabel, Javier; Krühler, Thomas; Levan, Andrew J.; Micha?owski, Micha? J.; Milvang-Jensen, Bo; Møller, Palle; Schulze, Steve; Tanvir, Nial R.; Watson, Darach

2012-09-01

137

A Novel Unbiased Proteomic Approach to Detect the Reactivity of Cerebrospinal Fluid in Neurological Diseases*  

PubMed Central

Neurodegenerative diseases, such as multiple sclerosis represent global health issues. Accordingly, there is an urgent need to understand the pathogenesis of this and other central nervous system disorders, so that more effective therapeutics can be developed. Cerebrospinal fluid is a potential source of important reporter molecules released from various cell types as a result of central nervous system pathology. Here, we report the development of an unbiased approach for the detection of reactive cerebrospinal fluid molecules and target brain proteins from patients with multiple sclerosis. To help identify molecules that may serve as clinical biomarkers for multiple sclerosis, we have biotinylated proteins present in the cerebrospinal fluid and tested their reactivity against brain homogenate as well as myelin and myelin-axolemmal complexes. Proteins were separated by two-dimensional gel electrophoresis, blotted onto membranes and probed separately with biotinylated unprocessed cerebrospinal fluid samples. Protein spots that reacted to two or more multiple sclerosis-cerebrospinal fluids were further analyzed by matrix assisted laser desorption ionization-time-of-flight time-of-flight mass spectrometry. In addition to previously reported proteins found in multiple sclerosis cerebrospinal fluid, such as ?? crystallin, enolase, and 14–3-3-protein, we have identified several additional molecules involved in mitochondrial and energy metabolism, myelin gene expression and/or cytoskeletal organization. These include aspartate aminotransferase, cyclophilin-A, quaking protein, collapsin response mediator protein-2, ubiquitin carboxy-terminal hydrolase L1, and cofilin. To further validate these findings, the cellular expression pattern of collapsin response mediator protein-2 and ubiquitin carboxy-terminal hydrolase L1 were investigated in human chronic-active MS lesions by immunohistochemistry. The observation that in multiple sclerosis lesions phosphorylated collapsin response mediator protein-2 was increased, whereas Ubiquitin carboxy-terminal hydrolase L1 was down-regulated, not only highlights the importance of these molecules in the pathology of this disease, but also illustrates the use of our approach in attempting to decipher the complex pathological processes leading to multiple sclerosis and other neurodegenerative diseases.

Menon, Krishnakumar N.; Steer, David L.; Short, Martin; Petratos, Steven; Smith, Ian; Bernard, Claude C. A.

2011-01-01

138

Age-related changes in rat cerebellar basket cells: a quantitative study using unbiased stereological methods  

PubMed Central

Cortical cerebellar basket cells are stable postmitotic cells; hence, they are liable to endure age-related changes. Since the cerebellum is a vital organ for the postural control, equilibrium and motor coordination, we aimed to determine the quantitative morphological changes in those interneurons with the ageing process, using unbiased techniques. Material from the cerebellar cortex (Crus I and Crus II) was collected from female rats aged 2, 6, 9, 12, 15, 18, 21 and 24 mo (5 animals per each age group), fixed by intracardiac perfusion, and processed for transmission electron microscopy, using conventional techniques. Serial semithin sections were obtained (5 blocks from each rat), enabling the determination of the number-weighted mean nuclear volume (by the nucleator method). On ultrathin sections, 25 cell profiles from each animal were photographed. The volume density of the nucleus, ground substance, mitochondria, Golgi apparatus (Golgi) and dense bodies (DB), and the mean surface density of the rough endoplasmic reticulum (RER) were determined, by point counting, using a morphometric grid. The mean total volumes of the soma and organelles and the mean total surface area of the RER [s?N (RER)] were then calculated. The results were analysed with 1-way ANOVA; posthoc pairwise comparisons of group means were performed using the Newman-Keuls test. The relation between age and each of the parameters was studied by regression analysis. Significant age-related changes were observed for the mean volumes of the soma, ground substance, Golgi, DB, and s?N (RER). Positive linear trends were found for the mean volumes of the ground substance, Golgi, and DB; a negative linear trend was found for the s?N (RER). These results indicate that rat cerebellar basket cells endure important age-related changes. The significant decrease in the s?N (RER) may be responsible for a reduction in the rate of protein synthesis. Additionally, it may be implicated in a cascade of events leading to cell damage due to the excitotoxic activity of glutamate, which could interfere in the functioning of the complex cerebellar neuronal network.

HENRIQUE, RUI M. F.; ROCHA, EDUARDO; REIS, ALCINDA; MARCOS, RICARDO; OLIVEIRA, MARIA H.; SILVA, MARIA W.; MONTEIRO, ROGERIO A. F.

2001-01-01

139

Generalized approach for using unbiased symmetric metrics with negative values: normalized mean bias factor and normalized mean absolute error factor  

SciTech Connect

Unbiased symmetric metrics provide a useful measure to quickly compare two datasets, with similar interpretations for both under and overestimations. Two examples include the normalized mean bias factor and normalized mean absolute error factor. However, the original formulations of these metrics are only valid for datasets with positive means. This paper presents a methodology to use and interpret the metrics with datasets that have negative means. The updated formulations give identical results compared to the original formulations for the case of positive means, so researchers are encouraged to use the updated formulations going forward without introducing ambiguity.

Gustafson, William I.; Yu, Shaocai

2012-10-23

140

Libraries of Stellar Spectra  

NSDL National Science Digital Library

This is a guide to online and abstract libraries of stellar spectra. This reference list also includes information about the spectra of Late-M, L, and T Dwarf stars, Morgan-Keenan spectral classification, the solar spectrum, spectrophotometric atlases, and automated and neural network classification.

2005-04-25

141

Spectra from Space  

NSDL National Science Digital Library

This site from the Exploratorium provides information on telescopes and observatories such as the Hubble Space Telescope that are being used to study spectra from space. Gamma-ray, x-ray, ultraviolet, and infrared spectra are all examined. The purpose and discoveries made by each observatory are included along with related hands-on activities like a liquid crystal IR detector activity.

Felter, Neil

2006-07-20

142

Units of ring spectra and Thom spectra  

Microsoft Academic Search

We review and extend the theory of Thom spectra and the associated\\u000aobstruction theory for orientations. We recall (from May, Quinn, and Ray) that\\u000aa commutative ring spectrum A has a spectrum of units gl(A). To a map of\\u000aspectra f: b -> bgl(A), we associate a commutative A-algebra Thom spectrum Mf,\\u000awhich admits a commutative A-algebra map to R

Matthew Ando; Andrew J. Blumberg; David J. Gepner; Michael J. Hopkins; Charles Rezk

2008-01-01

143

Unbiased group-wise image registration: applications in brain fiber tract atlas construction and functional connectivity analysis.  

PubMed

We propose an unbiased implicit-reference group-wise (IRG) image registration method and demonstrate its applications in the construction of a brain white matter fiber tract atlas and the analysis of resting-state functional MRI (fMRI) connectivity. Most image registration techniques pair-wise align images to a selected reference image and group analyses are performed in the reference space, which may produce bias. The proposed method jointly estimates transformations, with an elastic deformation model, registering all images to an implicit reference corresponding to the group average. The unbiased registration is applied to build a fiber tract atlas by registering a group of diffusion tensor images. Compared to reference-based registration, the IRG registration improves the fiber track overlap within the group. After applying the method in the fMRI connectivity analysis, results suggest a general improvement in functional connectivity maps at a group level in terms of larger cluster size and higher average t-scores. PMID:20703687

Geng, Xiujuan; Gu, Hong; Shin, Wanyong; Ross, Thomas J; Yang, Yihong

2010-05-25

144

Incoherent radar spectra  

Microsoft Academic Search

General expressions for the incoherent scatter spectra are presented. These are relevant for the UHF radar in the monostatic backscatter case (thus excluding only the effect of the magnetic field), based on the Nyquist approach.

Matti K. Vallinkoski

1987-01-01

145

Thermodynamic analysis of spectra  

SciTech Connect

Although random matrix theory had its initial application to neutron resonances, there is a relative scarcity of suitable nuclear data. The primary reason for this is the sensitivity of the standard measures used to evaluate spectra--the spectra must be essential pure (no state with a different symmetry) and complete (no states missing). Additional measures that are less sensitive to these experimental limitations are of significant value. The standard measure for long range order is the {delta}{sub 3} statistic. In the original paper that introduced this statistic, Dyson and Mehta also attempted to evaluate spectra with thermodynamic variables obtained from the circular orthogonal ensemble. We consider the thermodynamic 'internal energy' and evaluate its sensitivity to experimental limitations such as missing and spurious levels. Monte Carlo simulations suggest that the internal energy is less sensitive to mistakes than is {delta}{sub 3}, and thus the internal energy can serve as a addition to the tool kit for evaluating experimental spectra.

Mitchell, G. E. [North Carolina State University, Raleigh, NC 27695 and Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Shriner, J. F. Jr. [Tennessee Technological University, Cookeville, TN 38505 (United States)

2008-04-04

146

Spectra over complex terrain  

SciTech Connect

Spectra have been measured over land downwind of a water surface, over hilltops and escarpments, and over rolling farmland. The following hypotheses can be used to explain the differences between these spectra. (1) For wavelengths short compared to the fetch over the new terrain, spectral densities are in equilibrium with the new terrain. (2) For wavelengths long compared to this fetch, spectral densities remain unchanged if the ground is horizontal. If the flow is over a steep hill, the low-frequency structure is modified by distortion of the mean flow, with the longitudinal component losing energy relative to the lateral and vertical components. Because vertical-velocity spectra contain relatively less low-frequency energy than horizontal-velocity spectra, energetic vertical-velocity fluctuations tend to be in equilibrium with local terrain.

Panofsky, H.A.; Larko, D.; Lipschutz, R.; Stone, G.

1981-01-01

147

An unbiased population-based search for the geometry optimization of Lennard-Jones clusters: 2 < or = N < or = 372.  

PubMed

This article presents the results obtained using an unbiased Population Based Search (PBS) for optimizing Lennard-Jones clusters. PBS is able to repeatedly obtain all putative global minima, for Lennard-Jones clusters in the range 2 < or = N < or = 372, as reported in the Cambridge Cluster Database. The PBS algorithm incorporates and extends key techniques that have been developed in other Lennard-Jones optimization algorithms over the last decade. Of particular importance are the use of cut-and-paste operators, structure niching (using the cluster strain energy as a metric), two-phase local search, and a new operator, Directed Optimization, which extends the previous concept of directed mutation. In addition, PBS is able to operate in a parallel mode for optimizing larger clusters. PMID:15841476

Pullan, Wayne

2005-07-15

148

Interpreting Astronomical Spectra  

NASA Astrophysics Data System (ADS)

Interpreting Astronomical Spectra D. Emerson Institute for Astronomy, Department of Physics and Astronomy, The University of Edingurgh "Interpreting Astronomical Spectra" describes how physical conditions such as temperature, density and composition can be obtained from the spectra of a broad range of astronomical environments ranging from the cold interstellar medium to very hot coronal gas and from stellar atmospheres to quasars. In this book the author has succeeded in providing a coherent and integrated approach to the interpretation of astronomical spectroscopy, placing the emphasis on the physical understanding of spectrum formation rather than on instrumental considerations. MKS units and consistent symbols are employed throughout so that the fundamental ideas common to diverse environments are made clear and the importance of different temperature ranges and densities can be seen. Aimed at senior undergraduates and graduates studying physics, astronomy and astrophysics, this book will also appeal to the professional astronomer.

Emerson, D.

1996-06-01

149

Interpreting Astronomical Spectra  

NASA Astrophysics Data System (ADS)

Interpreting Astronomical Spectra D. Emerson Institute for Astronomy, Department of Physics and Astronomy, The University of Edingurgh "Interpreting Astronomical Spectra" describes how physical conditions such as temperature, density and composition can be obtained from the spectra of a broad range of astronomical environments ranging from the cold interstellar medium to very hot coronal gas and from stellar atmospheres to quasars. In this book the author has succeeded in providing a coherent and integrated approach to the interpretation of astronomical spectroscopy, placing the emphasis on the physical understanding of spectrum formation rather than on instrumental considerations. MKS units and consistent symbols are employed throughout so that the fundamental ideas common to diverse environments are made clear and the importance of different temperature ranges and densities can be seen. Aimed at senior undergraduates and graduates studying physics, astronomy and astrophysics, this book will also appeal to the professional astronomer.

Emerson, D.

1999-03-01

150

Spectra of Ternary Alloys  

Microsoft Academic Search

The vibrational frequency-dsitribution spectra of the random one-dimensional ternary alloy AcB1-cC are accurately predicted for the first time by a statistical theory of small clusters embedded in a coherent-potential-approximation effective medium. The theory can be applied practically to real three-dimensional alloys.

Charles W. Myles; John D. Dow

1979-01-01

151

Moderation of neutron spectra  

SciTech Connect

Most of the accelerators that produce the various microenergetic neutron sources required for low-energy neutron dosimetry studies have been shut down. One alternative to accelerator-produced sources is the use of fission neutron or ({alpha},n) sources with unique neutron spectra. The problem with this solution is that maintenance of these sources is impractical. To help overcome this impracticality, the authors propose the use of moderating materials to produce a variety of spectra using a minimum number of sources. In the study, they performed Monte Carlo transport calculations under the following conditions: transporting neutrons from bare {sup 252}Cf or {sup 241}Am-Be sources from the center of various-sized spheres; tallying neutron spectra at 50 cm from the source. Of the twelve different moderating materials they studied, they found pure copper to be an ideal moderator. In this paper, they present flux-weighted energies, neutron spectra, and dose information for both {sup 252}Cf and {sup 241}Am-Be sources in bare and six-moderator configurations.

Hsu, H.H.; Chen, J. [Los Alamos National Lab., NM (United States). Health Physics Measurements Group

1997-05-01

152

The absolute number of nerve cells in substantia nigra in normal subjects and in patients with Parkinson's disease estimated with an unbiased stereological method  

Microsoft Academic Search

Using an unbiased stereological technique, the total numbers of pigmented and non-pigmented neurons were estimated in the substantia nigra of seven patients with Parkinson's disease and seven control patients. Compared with the controls, in which the average total number of pigmented neurons was 550,000, the number of neurons was reduced by 66% in the patients. The average total number of

B Pakkenberg; A Møller; H J Gundersen; A Mouritzen Dam; H Pakkenberg

1991-01-01

153

Cost-Efiective Unbiased Estimation of Exponential Mean Life - Comparison of Ranked Set Sampling vis-a-vis Simple Random Sampling  

Microsoft Academic Search

This paper studies the problem of unbiased estimation of the mean of exponential life distribution of items which are to be put on test. The performance of the mean based on Simple Random Sampling is compared against that based on Ranked Set Sampling - taking into account possible cost structures. Also taken into account is the \\\\proflt\\

Karabi Sinha

154

Multispectral processing without spectra  

NASA Astrophysics Data System (ADS)

It is often the case that multiplications of whole spectra, component by component, must be carried out, for example when light reflects from or is transmitted through materials. This leads to particularly taxing calculations, especially in spectrally based ray tracing or radiosity in graphics, making a full-spectrum method prohibitively expensive. Nevertheless, using full spectra is attractive because of the many important phenomena that can be modeled only by using all the physics at hand. We apply to the task of spectral multiplication a method previously used in modeling RGB-based light propagation. We show that we can often multiply spectra without carrying out spectral multiplication. In previous work J. Opt. Soc. Am. A 11 , 1553 (1994) we developed a method called spectral sharpening, which took camera RGBs to a special sharp basis that was designed to render illuminant change simple to model. Specifically, in the new basis, one can effectively model illuminant change by using a diagonal matrix rather than the 33 linear transform that results from a three-component finite-dimensional model G. Healey and D. Slater, J. Opt. Soc. Am. A 11 , 3003 (1994). We apply this idea of sharpening to the set of principal components vectors derived from a representative set of spectra that might reasonably be encountered in a given application. With respect to the sharp spectral basis, we show that spectral multiplications can be modeled as the multiplication of the basis coefficients. These new product coefficients applied to the sharp basis serve to accurately reconstruct the spectral product. Although the method is quite general, we show how to use spectral modeling by taking advantage of metameric surfaces, ones that match under one light but not another, for tasks such as volume rendering. The use of metamers allows a user to pick out or merge different volume structures in real time simply by changing the lighting. 2003 Optical Society of America

Drew, Mark S.; Finlayson, Graham D.

2003-07-01

155

Multispectral processing without spectra.  

PubMed

It is often the case that multiplications of whole spectra, component by component, must be carried out,for example when light reflects from or is transmitted through materials. This leads to particularly taxing calculations, especially in spectrally based ray tracing or radiosity in graphics, making a full-spectrum method prohibitively expensive. Nevertheless, using full spectra is attractive because of the many important phenomena that can be modeled only by using all the physics at hand. We apply to the task of spectral multiplication a method previously used in modeling RGB-based light propagation. We show that we can often multiply spectra without carrying out spectral multiplication. In previous work [J. Opt. Soc. Am. A 11, 1553 (1994)] we developed a method called spectral sharpening, which took camera RGBs to a special sharp basis that was designed to render illuminant change simple to model. Specifically, in the new basis, one can effectively model illuminant change by using a diagonal matrix rather than the 3 x 3 linear transform that results from a three-component finite-dimensional model [G. Healey and D. Slater, J. Opt. Soc. Am. A 11, 3003 (1994)]. We apply this idea of sharpening to the set of principal components vectors derived from a representative set of spectra that might reasonably be encountered in a given application. With respect to the sharp spectral basis, we show that spectral multiplications can be modeled as the multiplication of the basis coefficients. These new product coefficients applied to the sharp basis serve to accurately reconstruct the spectral product. Although the method is quite general, we show how to use spectral modeling by taking advantage of metameric surfaces, ones that match under one light but not another, for tasks such as volume rendering. The use of metamers allows a user to pick out or merge different volume structures in real time simply by changing the lighting. PMID:12868625

Drew, Mark S; Finlayson, Graham D

2003-07-01

156

Martian neutron leakage spectra  

SciTech Connect

Energy spectra of Martian leakage neutrons are calculated by a high-energy nucleon-meson transport code using a Monte Carlo technique and a one-dimensional diffusion accelerated neutral-particle transport code, which solves the Boltzmann equation. Four series of calculations were made to simulate (1) a uniform surface layer containing various amounts of H/sub 2/O, (2) different burial depths of a 50% H/sub 2/O layer underneath a 1% H/sub 2/O layer, (3) changing atmospheric pressure, and (4) a thick CO/sub 2/ ice sheet overlying a ''dirty'' water ice sheet. We found that all calculated spectra at energies less than about 1000 eV could be fitted by a superposition of thermal and epithermal functions having four free parameters. Two of these parameters, the thermal and epithermal amplitudes, were found to vary systematically over ranges exceeding 1 order of magnitude and to specify uniquely the configuration in each of the series. We conclude that measurements of leakage neutron spectra should allow determination of the hydrogen content of surface layers buried to depths up to about 100 g/cm/sup 2/ and determination of the thickness of a polar dry ice cap up to thicknesses of about 250 g/cm/sup 2/. Variations of these parameters were also shown to depend on the composition of the assumed surface layers through the average atomic mass and the macroscopic scattering and absorption cross sections. copyright American Geophysical Union 1988

Drake, D.M.; Feldman, W.C.; Jakosky, B.M.

1988-06-10

157

Martian neutron leakage spectra  

NASA Astrophysics Data System (ADS)

A high-energy nucleon-meson transport code is used to calculate energy spectra of Martian leakage neutrons. Four calculations are used to simulate a uniform surface layer containing various amounts of water, different burial depths of a 50 percent water layer underneath a 1 percent water layer, changing atmospheric pressure, and a thick carbon dioxide ice sheet overlying a "dirty" water ice sheet. Calculated spectra at energies less than about 1000 eV were fitted by a superposition of thermal and epithermal functions having four free parameters, two of which (thermal and epithermal amplitudes) were found to vary systematically and to specify uniquely the configuration in each of the series. Parameter variations depend on the composition of the assumed surface layers through the average atomic mass and the macroscopic scattering and absorption cross sections. It is concluded that measurements of leakage neutron spectra should allow determination of the hydrogen content of surface layers buried to depths up to about 100 g/sq. cm and determination of the thickness of a polar dry ice cap up to a thickness of about 250 g/sq. cm.

Drake, D. M.; Feldman, W. C.; Jakosky, B. M.

1988-06-01

158

Unbiased probing of the entire hepatitis C virus life cycle identifies clinical compounds that target multiple aspects of the infection  

PubMed Central

Over 170 million people are chronically infected by the hepatitis C virus (HCV) and at risk for dying from liver cirrhosis and hepatocellular carcinoma. Current therapy is expensive, associated with significant side effects, and often ineffective. Discovery of antiviral compounds against HCV traditionally involves a priori target identification followed by biochemical screening and confirmation in cell-based replicon assays. Typically, this results in the discovery of compounds that address a few predetermined targets and are prone to select for escape variants. To attempt to identify antiviral compounds with broad target specificity, we developed an unbiased cell-based screening system involving multiple rounds of infection in a 96-well format. Analysis of a publicly available library of 446 clinically approved drugs identified 33 compounds that targeted both known and previously unexplored aspects of HCV infection, including entry, replication, and assembly. Discovery of novel viral and cellular targets in this manner will broaden the therapeutic armamentarium against this virus, allowing for the development of drug mixtures that should reduce the likelihood of mutational escape.

Gastaminza, Pablo; Whitten-Bauer, Christina; Chisari, Francis V.

2009-01-01

159

The cerebrum and cerebellum of the fixed human brain: efficient and unbiased estimates of volumes and cortical surface areas.  

PubMed Central

Extremely old and relatively new stereological methods for the efficient and unbiased estimation of volumes and surface areas were applied to fixed human brains. Brains from twelve subjects (six males aged 76-81 years, six females aged 70-98 years) were hemisected. Cerebral hemispheres and cerebellar halves from both sides were sliced systematic randomly for Cavalieri estimates of volume and vertical sectioning estimates of cortical surface area. Weights and linear dimensions were also recorded. It took less than 30 minutes per cerebral hemisphere to estimate total volume and cortical surface area. Cerebellar halves were analysed even more quickly. No significant differences between brain sides and no interaction effects were found but sex differences were confirmed. For male cerebrum (both hemispheres combined), the average volume was 840 cm3 and cortical surface area was 1640 cm2. Two thirds of this surface was hidden within sulci and in the insula. Cortical volume was 320 cm2 with an arithmetic mean thickness of 2.2 mm. In females the cerebral hemisphere was smaller and the cortex was less extensive but just as voluminous. In males, the cerebellum occupied 70 cm3 with a cortical surface of 550 cm2 of which 86% was hidden in fissures. Values were not significantly different from those found in females.

Henery, C C; Mayhew, T M

1989-01-01

160

Modeling the neurovascular niche: unbiased transcriptome analysis of the murine subventricular zone in response to hypoxic insult.  

PubMed

Premature infants often experience chronic hypoxia, resulting in cognitive & motor neurodevelopmental handicaps. These sometimes devastating handicaps are thought to be caused by compromised neural precursor cell (NPC) repair/recovery resulting in variable central nervous system (CNS) repair/recovery. We have identified differential responses of two mouse strains (C57BL/6 & CD1) to chronic hypoxia that span the range of responsiveness noted in the premature human population. We previously correlated several CNS tissue and cellular behaviors with the different behavioral parameters manifested by these two strains. In this report, we use unbiased array technology to interrogate the transcriptome of the subventricular zone (SVZ) in these strains. Our results illustrate differences in mRNA expression in the SVZ of both C57BL/6 and CD1 mice following hypoxia as well as differences between C57BL/6 and CD1 SVZ under both normoxic and hypoxic conditions. Differences in expression were found in gene sets associated with Sox10-mediated neural functions that explain, in part, the differential cognitive and motor responsiveness to hypoxic insult. This may shed additional light on our understanding of the variable responses noted in the human premature infant population and facilitate early intervention approaches. Further interrogation of the differentially expressed gene sets will provide a more complete understanding of the differential responses to, and recovery from, hypoxic insult allowing for more informed modeling of the ranges of disease severity observed in the very premature human population. PMID:24146847

Li, Qi; Canosa, Sandra; Flynn, Kelly; Michaud, Michael; Krauthammer, Michael; Madri, Joseph A

2013-10-11

161

Modeling the Neurovascular Niche: Unbiased Transcriptome Analysis of the Murine Subventricular Zone in Response to Hypoxic Insult  

PubMed Central

Premature infants often experience chronic hypoxia, resulting in cognitive & motor neurodevelopmental handicaps. These sometimes devastating handicaps are thought to be caused by compromised neural precursor cell (NPC) repair/recovery resulting in variable central nervous system (CNS) repair/recovery. We have identified differential responses of two mouse strains (C57BL/6 & CD1) to chronic hypoxia that span the range of responsiveness noted in the premature human population. We previously correlated several CNS tissue and cellular behaviors with the different behavioral parameters manifested by these two strains. In this report, we use unbiased array technology to interrogate the transcriptome of the subventricular zone (SVZ) in these strains. Our results illustrate differences in mRNA expression in the SVZ of both C57BL/6 and CD1 mice following hypoxia as well as differences between C57BL/6 and CD1 SVZ under both normoxic and hypoxic conditions. Differences in expression were found in gene sets associated with Sox10-mediated neural functions that explain, in part, the differential cognitive and motor responsiveness to hypoxic insult. This may shed additional light on our understanding of the variable responses noted in the human premature infant population and facilitate early intervention approaches. Further interrogation of the differentially expressed gene sets will provide a more complete understanding of the differential responses to, and recovery from, hypoxic insult allowing for more informed modeling of the ranges of disease severity observed in the very premature human population.

Li, Qi; Canosa, Sandra; Flynn, Kelly; Michaud, Michael

2013-01-01

162

Approximate best linear unbiased channel estimation for multi-antenna frequency selective channels with applications to digital TV systems  

NASA Astrophysics Data System (ADS)

We provide an iterative and a non-iterative channel impulse response (CIR) estimation algorithm for communication receivers with multiple-antenna. Our algorithm is best suited for communication systems which utilize a periodically transmitted training sequence within a continuous stream of information symbols, and the receivers for this particular system are expected work in a severe frequency selective multipath environment with long delay spreads relative to the length of the training sequence. The iterative procedure calculates the (semi-blind) Best Linear Unbiased Estimate (BLUE) of the CIR. The non-iterative version is an approximation to the BLUE CIR estimate, denoted by a-BLUE, achieving almost similar performance, with much lower complexity. Indeed we show that, with reasonable assumptions, a-BLUE channel estimate can be obtained by using a stored copy of a pre-computed matrix in the receiver which enables the use of the initial CIR estimate by the subsequent equalizer tap weight calculator. Simulation results are provided to demonstrate the performance of the novel algorithms for 8-VSB ATSC Digital TV system. We also provide a simulation study of the robustness of the a-BLUE algorithm to timing and carrier phase offsets.

Ozen, Serdar; Pladdy, Christopher; Nerayanuru, Sreenivasa M.; Fimoff, Mark J.; Zoltowski, Michael D.

2004-08-01

163

Unbiased estimates of number and size of rat dorsal root ganglion cells in studies of structure and cell survival.  

PubMed

For quantitative studies of rat dorsal root ganglion (DRG) in experimental models stereological principles offer a number of different techniques. The application, however, requires knowledge of the anatomy and cytology of the ganglion, considerations of sampling and choosing between the many estimators available. For number and volume estimates in thick glycolmethacrylate sections the optical fractionator and the vertical planar rotator technique in most cases provide sufficient efficiency and are simple to use. Classification of the neurons in the DRG into A- and B-cells is of value in experimental conditions where the two cell types can react differently. Studies on development and subclassification of neuronal DRG cells will gain from application of stereological methods, also. Until now the methods have mainly been applied in studies of axotomy and in a few intoxication models where the time course of cell loss and changes in perikarya volume are important parameters. Further quantitative studies providing better understanding of distribution and expression of neuropeptides, cytokines, apoptotic molecules etc. will provide insight for future therapeutic approaches in neurodegenerative disorders. The more demanding staining techniques require less restrictive embedding media, but unbiased principles are available for almost all the stereological techniques applied to tissue only deformed after sectioning. PMID:15322376

Tandrup, Trine

2004-03-01

164

Two Distinct States of the HAMP Domain from Sensory Rhodopsin Transducer Observed in Unbiased Molecular Dynamics Simulations  

PubMed Central

HAMP domain is a ubiquitous module of bacterial and archaeal two-component signaling systems. Considerable progress has been made recently in studies of its structure and conformational changes. However, the mechanism of signal transduction through the HAMP domain is not clear. It remains a question whether all the HAMPs have the same mechanism of action and what are the differences between the domains from different protein families. Here, we present the results of unbiased molecular dynamics simulations of the HAMP domain from the archaeal phototaxis signal transducer NpHtrII. Two distinct conformational states of the HAMP domain are observed, that differ in relative position of the helices AS1 and AS2. The longitudinal shift is roughly equal to a half of an ?-helix turn, although sometimes it reaches one full turn. The states are closely related to the position of bulky hydrophobic aminoacids at the HAMP domain core. The observed features are in good agreement with recent experimental results and allow us to propose that the states detected in the simulations are the resting state and the signaling state of the NpHtrII HAMP domain. To the best of our knowledge, this is the first observation of the same HAMP domain in different conformations. The simulations also underline the difference between AMBER ff99-SB-ILDN and CHARMM22-CMAP forcefields, as the former favors the resting state and the latter favors the signaling state.

Gushchin, Ivan; Gordeliy, Valentin; Grudinin, Sergei

2013-01-01

165

Suppression of nonsense-mediated mRNA decay permits unbiased gene trapping in mouse embryonic stem cells  

PubMed Central

An international collaborative project has been proposed to inactivate all mouse genes in embryonic stem (ES) cells using a combination of random and targeted insertional mutagenesis techniques. Random gene trapping will be the first choice in the initial phase, and gene-targeting experiments will then be carried out to individually knockout the remaining ‘difficult-to-trap’ genes. One of the most favored techniques of random insertional mutagenesis is promoter trapping, which only disrupts actively transcribed genes. Polyadenylation (poly-A) trapping, on the other hand, can capture a broader spectrum of genes including those not expressed in the target cells, but we noticed that it inevitably selects for the vector integration into the last introns of the trapped genes. Here, we present evidence that this remarkable skewing is caused by the degradation of a selectable-marker mRNA used for poly-A trapping via an mRNA-surveillance mechanism, nonsense-mediated mRNA decay (NMD). We also report the development of a novel poly-A-trap strategy, UPATrap, which suppresses NMD of the selectable-marker mRNA and permits the trapping of transcriptionally silent genes without a bias in the vector-integration site. We believe the UPATrap technology enables a simple and straightforward approach to the unbiased inactivation of all mouse genes in ES cells.

Shigeoka, Toshiaki; Kawaichi, Masashi; Ishida, Yasumasa

2005-01-01

166

An unbiased in vivo screen reveals multiple transcription factors that control HPV E6-regulated hTERT in keratinocytes.  

PubMed

Activation of telomerase by human papillomavirus 16 (HPV16) E6 is a critical step for cell immortalization and transformation in human foreskin keratinocytes (HFKs). Multiple transcription factors have been identified as being involved in E6-induced hTERT expression. Here, we adapted an unbiased in vivo screen using a LacO-LacI system in human cells to discover hTERT promoter-interacting regulators. This approach allowed us to identify a novel hTERT repressor, Maz, which bound the hTERT promoter. E6 expression reduced Maz binding and correspondingly increased Sp1 binding at the hTERT promoter. Knockdown of Maz further increased histone acetylation, as well as hTERT expression in the presence of E6. Overall, these data indicate the utility of a novel screen for promoter-interacting and transcription-regulating proteins. These data also highlight multiple factors that normally regulate hTERT repression in HFKs, and therefore are targeted by E6 for hTERT expression. PMID:24074563

Xu, Mei; Katzenellenbogen, Rachel A; Grandori, Carla; Galloway, Denise A

2013-08-08

167

Staggered ladder spectra.  

PubMed

We exactly solve a Fokker-Planck equation by determining its eigenvalues and eigenfunctions: we construct nonlinear second-order differential operators which act as raising and lowering operators, generating ladder spectra for the odd- and even-parity states. The ladders are staggered: the odd-even separation differs from even-odd. The Fokker-Planck equation corresponds, in the limit of weak damping, to a generalized Ornstein-Uhlenbeck process where the random force depends upon position as well as time. The process describes damped stochastic acceleration, and exhibits anomalous diffusion at short times and a stationary non-Maxwellian momentum distribution. PMID:16486675

Arvedson, E; Wilkinson, M; Mehlig, B; Nakamura, K

2006-01-25

168

Spectra From Space : Main Menu  

NSDL National Science Digital Library

On-line science lesson (grades 7 - 9) - students learn about satellite spectra research, electromagnetic spectrum, do hands-on activities. In this lesson students investigate satellite missions operating in four electromagnetic bands. Students learn about spectra and why satellites gather certain kinds of spectra from space by using the Internet and doing hands-on activities. From the University of California, Berkeley.

1997-01-01

169

DISPLACEMENT SPECTRA FOR SEISMIC DESIGN  

Microsoft Academic Search

Displacement-based seismic design and assessment of structures require the reliable definition of displacement spectra for a wide range of periods and damping levels. The displacement spectra derived from acceleration spectra in existing seismic codes do not provide a suitable answer and there are no existing frequency-dependent attenuation relationships derived specifically for this purpose. Using a carefully processed dataset of European

JULIAN J. BOMMER; AMR S. ELNASHAI

1999-01-01

170

Best Linear Unbiased Prediction of Genomic Breeding Values Using a Trait-Specific Marker-Derived Relationship Matrix  

PubMed Central

Background With the availability of high density whole-genome single nucleotide polymorphism chips, genomic selection has become a promising method to estimate genetic merit with potentially high accuracy for animal, plant and aquaculture species of economic importance. With markers covering the entire genome, genetic merit of genotyped individuals can be predicted directly within the framework of mixed model equations, by using a matrix of relationships among individuals that is derived from the markers. Here we extend that approach by deriving a marker-based relationship matrix specifically for the trait of interest. Methodology/Principal Findings In the framework of mixed model equations, a new best linear unbiased prediction (BLUP) method including a trait-specific relationship matrix (TA) was presented and termed TABLUP. The TA matrix was constructed on the basis of marker genotypes and their weights in relation to the trait of interest. A simulation study with 1,000 individuals as the training population and five successive generations as candidate population was carried out to validate the proposed method. The proposed TABLUP method outperformed the ridge regression BLUP (RRBLUP) and BLUP with realized relationship matrix (GBLUP). It performed slightly worse than BayesB with an accuracy of 0.79 in the standard scenario. Conclusions/Significance The proposed TABLUP method is an improvement of the RRBLUP and GBLUP method. It might be equivalent to the BayesB method but it has additional benefits like the calculation of accuracies for individual breeding values. The results also showed that the TA-matrix performs better in predicting ability than the classical numerator relationship matrix and the realized relationship matrix which are derived solely from pedigree or markers without regard to the trait. This is because the TA-matrix not only accounts for the Mendelian sampling term, but also puts the greater emphasis on those markers that explain more of the genetic variance in the trait.

Zhang, Zhe; Liu, Jianfeng; Ding, Xiangdong; Bijma, Piter; de Koning, Dirk-Jan; Zhang, Qin

2010-01-01

171

How Psychiatry Journals Support the Unbiased Translation of Clinical Research. A Cross-Sectional Study of Editorial Policies  

PubMed Central

Introduction Reporting guidelines (e.g. CONSORT) have been developed as tools to improve quality and reduce bias in reporting research findings. Trial registration has been recommended for countering selective publication. The International Committee of Medical Journal Editors (ICMJE) encourages the implementation of reporting guidelines and trial registration as uniform requirements (URM). For the last two decades, however, biased reporting and insufficient registration of clinical trials has been identified in several literature reviews and other investigations. No study has so far investigated the extent to which author instructions in psychiatry journals encourage following reporting guidelines and trial registration. Method Psychiatry Journals were identified from the 2011 Journal Citation Report. Information given in the author instructions and during the submission procedure of all journals was assessed on whether major reporting guidelines, trial registration and the ICMJE’s URM in general were mentioned and adherence recommended. Results We included 123 psychiatry journals (English and German language) in our analysis. A minority recommend or require 1) following the URM (21%), 2) adherence to reporting guidelines such as CONSORT, PRISMA, STROBE (23%, 7%, 4%), or 3) registration of clinical trials (34%). The subsample of the top-10 psychiatry journals (ranked by impact factor) provided much better but still improvable rates. For example, 70% of the top-10 psychiatry journals do not ask for the specific trial registration number. Discussion Under the assumption that better reported and better registered clinical research that does not lack substantial information will improve the understanding, credibility, and unbiased translation of clinical research findings, several stakeholders including readers (physicians, patients), authors, reviewers, and editors might benefit from improved author instructions in psychiatry journals. A first step of improvement would consist in requiring adherence to the broadly accepted reporting guidelines and to trial registration.

Knuppel, Hannes; Metz, Courtney; Meerpohl, Joerg J.; Strech, Daniel

2013-01-01

172

Computation of Spiral Spectra  

NASA Astrophysics Data System (ADS)

A computational linear stability analysis of spiral waves in a reaction-diffusion equation is performed on large disks. As the disk radius R increases, eigenvalue spectra converge to the absolute spectrum predicted by Sandstede and Scheel. The convergence rate is consistent with 1/R, except possibly near the edge of the spectrum. Eigenfunctions computed on large disks are compared with predicted exponential forms. Away from the edge of the absolute spectrum the agreement is excellent, while near the edge computed eigenfunctions deviate from predictions, probably due to finite-size effects. In addition to eigenvalues associated with the absolute spectrum, computations reveal point eigenvalues. The point eigenvalues and associated eigenfunctions responsible for both core and far-field breakup of spiral waves are shown.

Wheeler, Paul; Barkley, Dwight

2006-01-01

173

Unbiased Stellar Parameters  

NASA Astrophysics Data System (ADS)

I report about ongoing efforts of the USM cool-star group to refine our ability to derive fundamental stellar parameters Teff, log g and [Xi / H] (chemical composition) for solar-type stars. In this contribution the focus lies on a universal gravity indicator, namely the iron ionization equilibrium. It is shown that a kinetic equilibrium or non-LTE approach for Fe i succeeds in fulfilling the trigonometric constraints coming from the Hipparcos satellite mission if and only if inelastic collisions with hydrogen are properly accounted for. Our model makes testable predictions for the gravities of metal-poor globular cluster giants in which non-LTE corrections are expected to reach up to +0.5 dex.

Korn, A. J.

174

Ultraviolet Spectra of the Complete 12-Micron Seyfert 1 Galaxy Sample  

NASA Astrophysics Data System (ADS)

We propose to obtain the first SWP spectra of UGC 5101, NGC 3511, and NGC 4602, to complete the coverage of the 121Lm Seyfert I galaxy sample. 12 micron selection provides the best unbiased bolometric flux-limited sample of AGNs (Spinoglio and Malkan 1989). We will also observe MKN 334, completing the SWP coverage of the optically-selected CfA Seyfert is, for comparison with the 12 micron sample. We are now compiling nearly complete multiwavelength space- and ground-based observations for the 12 micron sample. The IUE data will be an essential part of this uniform database, since many of the most important line and continuum features of AGNs fall in the wavelength range of the SWP camera. Statistical analysis of this complete unbiased sample will allow for the testing of models which attempt to explain the wide range of observed AGN properties as resulting from a continuous sequence in a few fundamental parameters In particular, we will test proposed paradigms in which the key parameters are viewing angle, size scale of the central engine, and/or the degree of dust-enshroudedness. This analysis will form the basis of Brian Rush's Ph.D. thesis at UCLA.

Malkan, Matthew A.

175

Robust automated mass spectra interpretation and chemical formula calculation using mixed integer linear programming.  

PubMed

Untargeted metabolite profiling using liquid chromatography and mass spectrometry coupled via electrospray ionization is a powerful tool for the discovery of novel natural products, metabolic capabilities, and biomarkers. However, the elucidation of the identities of uncharacterized metabolites from spectral features remains challenging. A critical step in the metabolite identification workflow is the assignment of redundant spectral features (adducts, fragments, multimers) and calculation of the underlying chemical formula. Inspection of the data by experts using computational tools solving partial problems (e.g., chemical formula calculation for individual ions) can be performed to disambiguate alternative solutions and provide reliable results. However, manual curation is tedious and not readily scalable or standardized. Here we describe an automated procedure for the robust automated mass spectra interpretation and chemical formula calculation using mixed integer linear programming optimization (RAMSI). Chemical rules among related ions are expressed as linear constraints and both the spectra interpretation and chemical formula calculation are performed in a single optimization step. This approach is unbiased in that it does not require predefined sets of neutral losses and positive and negative polarity spectra can be combined in a single optimization. The procedure was evaluated with 30 experimental mass spectra and was found to effectively identify the protonated or deprotonated molecule ([M + H](+) or [M - H](-)) while being robust to the presence of background ions. RAMSI provides a much-needed standardized tool for interpreting ions for subsequent identification in untargeted metabolomics workflows. PMID:24032353

Baran, Richard; Northen, Trent R

2013-09-27

176

Xspect / Xpol : CMB angular power spectra estimator using cross-correlation  

NASA Astrophysics Data System (ADS)

We present a method to estimate the angular power spectrum of the CMB anisotropies for both temperature and polarization. We compute cross power spectra from a set of maps coming from different detectors or different instruments. Each of these cross power spectra is an unbiased estimate of the C(l) as long as the detector noises are uncorrelated. Then the spectra are optimally combined into a final power spectrum and analytical estimates of the power spectrum error bars are computed. This method presents three main advantages : (1) no estimation of the noise power spectrum is needed, (2) error bars can be computed very fast as no Monte-Carlo simulations are involved, (3) weighting scheme including the covering factor can be individually taken into account for each input map. We show with simulations of Planck HFI-like surveys that the power spectra and their error bars are recovered without bias at all angular scales. In addition, we apply this method to simulations of WMAP high frequency channels, which are comparable to Planck- LFI.

Tristram, Matthieu

177

Cosmology from quasar spectra  

NASA Astrophysics Data System (ADS)

High resolution spectroscopy of high redshift quasar spectra enables us to investigate the properties of the intergalactic medium (IGM) and measure cosmological parameters from the Lya forest. Toward high precision cosmology, this dissertation presents the following four topics. (1) Principal Component Analysis (PCA) on quasar spectrum: We introduce the PCA to describe quasar emission lines and continua quantitatively, and we attempt to make a prediction of the continuum shape in the Lya forest using wavelengths redward of Lya emission. (2) Flux calibration of Keck HIRES data: On our way to achieve high accuracy measurement, it was necessary to develop new calibration schemes and explore the origin of systematic errors. My contribution includes the following and is discussed throughout the thesis: (i) the development of the flux calibration scheme, (ii) the discovery of three emission lines in the Lya forest, (iii) the establishment of high resolution standard star spectra, and (iv) the identification of ozone lines in the spectrum. (3) D/H measurement: We present precise measurements of the primordial deuterium to hydrogen ratio (D/ H) toward two quasars, HS0105+1619 and Q1243+3047, which constrains the baryon to photon ratio e = 5.9 +/- 0.5 x 10 -10 or the baryon density O b h 2 = 0.0214 +/- 0.0020 via the Big Bang Nucleosynthesis theory. (4) Studies of the Lya forest at z ~ 2: We also present the measurements of the total amount of neutral hydrogen absorption in the IGM. We compare our observed data with hydrodynamic simulations and find good agreement when we use the following cosmological parameters: H o = 71 kin s -1 Mpc -1 , O L = 0.73, O m = 0.27, O b = 0.044, the amplitude of the power spectrum s 8 = 0.9, and the photoinization rate G 912 = (1.44 +/- 0.11) x 10 -12 s -1 . We conclude that the measurements of the cosmological parameters from our primordial D/H measurements, recent WMAP satellite observation of the cosmic microwave background, and our the total amount of neutral hydrogen in the IGM at z ~ 2 are in a concordance with the LCDM model.

Suzuki, Nao

2005-11-01

178

Hybrid estimation of cosmic microwave background polarization power spectra  

NASA Astrophysics Data System (ADS)

This paper generalizes the hybrid power spectrum estimation method developed in a previous paper to the estimation of polarization power spectra of the cosmic microwave background radiation. The hybrid power spectrum estimator is unbiased and we show that it is close to optimal at all multipoles, provided the pixel noise satisfies certain constraints. Furthermore, the hybrid estimator is computationally fast and can easily be incorporated in a Monte Carlo chain for Planck-sized data sets, which may be essential to account for realistic noise covariance and systematic errors. Simple formulae are given for the covariance matrices, including uncorrelated inhomogeneous instrumental noise, and these are tested extensively against numerical simulations. We compare the behaviour of simple pseudo-Cl (PCL) estimates with maximum-likelihood estimates at low multipoles. For realistic sky cuts, maximum-likelihood estimates reduce very significantly the mixing of E and B modes. To achieve limits on the scalar-tensor ratio of r << 0.1 from sky maps with realistic sky cuts, maximum-likelihood methods, or PCL estimators based on unambiguous E and B modes, will be essential.

Efstathiou, G.

2006-07-01

179

First Optical Spectra of Newly Detected Swift BAT AGN  

NASA Astrophysics Data System (ADS)

The Swift BAT hard X-ray survey is providing an unbiased look at AGN because in the 14-195 keV hard X-ray regime, dust and gas obscuration does not prevent their detection. We present the optical and X-ray spectra of 21 newly discovered BAT AGN from the 58 and 70-month catalogs and report their redshifts, optical properties, and classifications for the first time. The optical follow-ups were done with the 3.5-meter telescope at Apache Point Observatory in New Mexico over 6 half-nights. The newly detected sources are either fainter, or more distant than the sources in the previous catalogs. The sample has a redshift range of z = 0.02 to 0.16, with the more obscured AGN at the lower redshifts. Ten of the sources exhibit broadlines (47%), indicative of Seyfert 1s, nine exhibit narrowlines (43%), indicative of Seyfert 2s, and two (10%) do not show any lines and have a flat spectrum.

Hogg, J. Drew; Winter, L.; Tueller, J.

2012-01-01

180

Time spectra of patent information  

Microsoft Academic Search

Information spectra are defined as intervals between equivalent information events. Their relations to negative binomial and negative polynomial distributions and urn models are explained. Basic properties of empirical information spectra from patent literature are shown and discussed in connection withHaitun's views on Z type information distributions,Sichel's GIGP model andTrofimenko's study on formation and decay of author groups.

M. Kunz

1987-01-01

181

Wavelet Denoising of Infrared Spectra  

Microsoft Academic Search

The application of wavelet denoising to infrared spectra was investigated. Six different wavelet denoising methods (SURE, VISU, HYBRID, MINMAX, MAD and WAVELET PACKETS) were applied to pure infrared spectra with various added levels of homo- and heteroscedastic noise. The performances of the wavelet denoising methods were compared with the standard Fourier and moving mean filtering in terms of root mean

Bjørn K. Alsberg; Andrew M. Woodward; Michael K. Winson; Jem Rowland; Douglas B. Kell

1997-01-01

182

SPECTRA-IV, benchmark spectra based on LIB-IV  

Microsoft Academic Search

Flux and adjoint spectra for each of the Cross Section Evaluation Working Group fast reactor benchmarks are numerically and graphically presented in this handbook. The spectra were computed using a 50-group cross-section library (LIB-IV) that was generated with the MINX processing code using ENDF\\/B-IV data. The graphical figures compare smooth interpolated curves for the central flux, edge flux, central adjoint,

Kidman

1979-01-01

183

Anisotropic spectra of acoustic turbulence  

SciTech Connect

We found universal anizopropic spectra of acoustic turbulence with the linear dispersion law {omega}(k)=ck within the framework of generalized kinetic equation which takes into account the finite time of three-wave interactions. This anisotropic spectra can assume both scale-invariant and non-scale-invariant form. The implications for the evolution of the acoustic turbulence with nonisotropic pumping are discussed. The main result of the article is that the spectra of acoustic turbulence tend to become more isotropic. (c) 2000 The American Physical Society.

L'vov, V. S. [Departments of Chemical Physics, The Weizmann Institute of Science, Rehovot 76100, (Israel); Institute for Automatization, Russian Academy of Science, Novosibirsk 630090, Russia (Russian Federation); L'vov, Yu. V. [Department of Mathematical Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Pomyalov, A. [Departments of Chemical Physics, The Weizmann Institute of Science, Rehovot 76100, (Israel)

2000-03-01

184

Raman Spectroscopy Databases | Spectra Databases  

NSDL National Science Digital Library

This site is a clearinghouse of vibrational frequencies and Raman, mass, fluorescence, neutron scattering and infrared spectra. Both organic and mineral databases are included. The site features free access from both university and industry sources.

Spectroscopynow.com

185

Forecasting and Verifying Hydrometeor Spectra.  

National Technical Information Service (NTIS)

Forecasts and measurements of ice water content, hydrometeor size spectra and crystal habit are being provided for Air Force tests. Climatology, synoptic, rawinsonde and satellite data are used for forecasts in excess of three hours. Shorter range forecas...

A. A. Barnes V. G. Plank

1976-01-01

186

RW Aur spectra (Alencar+, 2005)  

NASA Astrophysics Data System (ADS)

The observations, obtained over a decade, were carried out at Lick Observatory. ************************************************************************** * * * A major hard disk failure on the author's workstation containing * * the FITS files of the spectra made the files actually unavailable * * * ************************************************************************** (1 data file).

Alencar, S. H. P.; Basri, G.; Hartmann, L.; Calvet, N.

2006-07-01

187

SPECTROSCOPIC PROPERTIES OF STAR-FORMING HOST GALAXIES AND TYPE Ia SUPERNOVA HUBBLE RESIDUALS IN A NEARLY UNBIASED SAMPLE  

SciTech Connect

We examine the correlation between supernova (SN) host-galaxy properties and their residuals in the Hubble diagram. We use SNe discovered during the Sloan Digital Sky Survey-II Supernova Survey, and focus on objects at a redshift of z < 0.15, where the selection effects of the survey are known to yield a complete Type Ia supernova (SN Ia) sample. To minimize the bias in our analysis with respect to measured host-galaxy properties, spectra were obtained for nearly all hosts, spanning a range in magnitude of -23 < M{sub r} < -17. In contrast to previous works that use photometric estimates of host mass as a proxy for global metallicity, we analyze host-galaxy spectra to obtain gas-phase metallicities and star formation rates (SFRs) from host galaxies with active star formation. From a final sample of {approx}40 emission-line galaxies, we find that light-curve-corrected SNe Ia are {approx}0.1 mag brighter in high-metallicity hosts than in low-metallicity hosts. We also find a significant (>3{sigma}) correlation between the Hubble Residuals of SNe Ia and the specific SFR of the host galaxy. We comment on the importance of SN/host-galaxy correlations as a source of systematic bias in future deep SN surveys.

D'Andrea, Chris B.; Gupta, Ravi R.; Sako, Masao; Morris, Matt [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); Nichol, Robert C.; Campbell, Heather; Lampeitl, Hubert [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Burnaby Road, Portsmouth PO1 3FX (United Kingdom); Brown, Peter J.; Olmstead, Matthew D. [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Frieman, Joshua A.; Kessler, Richard [Kavli Institute for Cosmological Physics, The University of Chicago, 5640 South Ellise Avenue, Chicago, IL 60637 (United States); Garnavich, Peter [Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Jha, Saurabh W. [Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States); Marriner, John [Center for Astrophysics, Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States); Schneider, Donald P. [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Smith, Mathew, E-mail: chris.dandrea@port.ac.uk [Astrophysics, Cosmology and Gravity Centre, Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, Cape Town (South Africa)

2011-12-20

188

MODELING EXTRAGALACTIC FOREGROUNDS AND SECONDARIES FOR UNBIASED ESTIMATION OF COSMOLOGICAL PARAMETERS FROM PRIMARY COSMIC MICROWAVE BACKGROUND ANISOTROPY  

SciTech Connect

Using the latest physical modeling and constrained by the most recent data, we develop a phenomenological parameterized model of the contributions to intensity and polarization maps at millimeter wavelengths from external galaxies and Sunyaev-Zeldovich effects. We find such modeling to be necessary for estimation of cosmological parameters from Planck data. For example, ignoring the clustering of the infrared background would result in a bias in n{sub s} of 7{sigma} in the context of an eight-parameter cosmological model. We show that the simultaneous marginalization over a full foreground model can eliminate such biases, while increasing the statistical uncertainty in cosmological parameters by less than 20%. The small increases in uncertainty can be significantly reduced with the inclusion of higher-resolution ground-based data. The multi-frequency analysis we employ involves modeling 46 total power spectra and marginalization over 17 foreground parameters. We show that we can also reduce the data to a best estimate of the cosmic microwave background power spectra, with just two principal components (with constrained amplitudes) describing residual foreground contamination.

Millea, M.; Knox, L. [Department of Physics, University of California, Davis, CA 95616 (United States); Dore, O. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Dudley, J.; Holder, G. [Department of Physics, McGill University, Montreal, Quebec H3A 2T8 (Canada); Shaw, L. [Department of Physics, Yale University, New Haven, CT 06520-8120 (United States); Song, Y.-S. [Korea Institute for Advanced Study, Seoul 130-722 (Korea, Republic of); Zahn, O. [Berkeley Center for Cosmological Physics, Department of Physics, University of California, and Lawrence Berkeley National Labs, Berkeley, CA 94720 (United States)

2012-02-10

189

Mutational spectra of human cancer  

Microsoft Academic Search

The purpose of this review is to summarize the evidence that can be used to reconstruct the etiology of human cancers from\\u000a mutations found in tumors. Mutational spectra of the tumor suppressor gene p53 (TP53) are tumor specific. In several cases, these mutational spectra can be linked to exogenous carcinogens, most notably for\\u000a sunlight-associated skin cancers, tobacco-associated lung cancers, and

Gerd P. Pfeifer; Ahmad Besaratinia

2009-01-01

190

Unbiased photoelectrochemical water splitting in Z-scheme device using W/Mo-doped BiVO4 and Zn(x)Cd(1-x)Se.  

PubMed

Photoelectrochemical water splitting to generate H2 and O2 using only photon energy (with no added electrical energy) has been demonstrated with dual n-type-semiconductor (or Z-scheme) systems. Here we investigated two different Z-scheme systems; one is comprised of two cells with the same metal-oxide semiconductor (W- and Mo-doped bismuth vanadate), that is, Pt-W/Mo-BiVO4, and the other is comprised of the metal oxide and a chalcogenide semiconductor, that is, Pt-W/Mo-BiVO4 and Zn(0.2)Cd(0.8)Se. The redox couples utilized in these Z-scheme configurations were I(-)/IO3(-) or S(2-)/S(n)(2-), respectively. An electrochemical analysis of the system in terms of cell components is shown to illustrate the behavior of the complete photoelectrochemical Z-scheme water-splitting system. H2 gas from the unbiased photolysis of water was detected using gas chromatography-mass spectroscopy and using a membrane-electrode assembly. The electrode configuration to achieve the maximum conversion efficiency from solar energy to chemical energy with the given materials and the Z-scheme is discussed. Here, the possibilities and challenges of Z-scheme unbiased photoelectrochemical water-splitting devices and the materials to achieve practical solar-fuel generation are discussed. PMID:23494937

Park, Hyun S; Lee, Heung Chan; Leonard, Kevin C; Liu, Guanjie; Bard, Allen J

2013-03-12

191

Unbiased quantitative assessment of Her-2 expression of circulating tumor cells in patients with metastatic and non-metastatic breast cancer.  

PubMed

Background Circulating tumor cells (CTCs) can provide the basis for a liquid biopsy and may guide the use of targeted therapies. We report on unbiased quantification of Her-2 protein expression of CTCs. Patients and methods Her-2 assessment of CTCs was carried out using the CellSearch(®) system in 103 metastatic (M1) and 88 non-metastatic (M0) breast-cancer patients. Expression of Her-2 on CTCs was determined by a manual review and an automated algorithm using Her-2- fluorescein isothiocyanate (FITC) fluorescence of leukocytes to determine the Her-2-expression threshold in each sample. Results Her-2 expression of CTCs varied greatly within and among patients compared with Her-2 expression of leukocytes. In M1 patients, a threshold of 75% of Her-2 positive CTCs in patients with ?5 CTCs was set. Applying this threshold, 9% of M1 patients with Her-2-negative primary tumors had Her-2-positive CTC status and 29% of M1 patients with Her-2-positive primary tumors had Her-2-negative CTC status. No Her-2 discrepancy was observed between CTCs and primary tumors in M0 patients. Conclusions Our findings demonstrate that Her-2 expression is heterogeneous among CTCs within each patient. We show the feasibility of unbiased quantitative and reproducible assessment of treatment targets on CTCs, opening a path towards personalized treatment. PMID:23275633

Ligthart, S T; Bidard, F-C; Decraene, C; Bachelot, T; Delaloge, S; Brain, E; Campone, M; Viens, P; Pierga, J-Y; Terstappen, L W M M

2012-12-27

192

Reduction of multielement mass spectra  

SciTech Connect

Even though the spectra obtained by inductively coupled plasma source spectrometry (ICP-MS) are relatively simple, their interpretation can be complicated by the presence of molecular and isobaric interferants. To the extent that isotopic abundances are known and constant, one can treat observed spectra as sums of known components. A linear decomposition approach for determining the concentrations of the components in a spectrum and correctly propagating uncertainties is presented. This technique differs from linear regression in that an exact fit is made to a subset of isotopes and goodness-of-fit is evaluated from the deviations between the predicted and measured intensities of the other, unfit isotopes. This technique can be applied to a wide range of spectral fitting problems. In this paper, its applicability to ICP-MS spectra is used to demonstrate the use and utility of the technique. 2 refs., 9 figs.

Russ, G.P. III; Caffee, M.W.; Hudson, G.B.; Storch, N.A.

1990-06-29

193

Qualitative Interpretation of Galaxy Spectra  

NASA Astrophysics Data System (ADS)

We describe a simple step-by-step guide to qualitative interpretation of galaxy spectra. Rather than an alternative to existing automated tools, it is put forward as an instrument for quick-look analysis and for gaining physical insight when interpreting the outputs provided by automated tools. Though the recipe is for general application, it was developed for understanding the nature of the Automatic Spectroscopic K-means-based (ASK) template spectra. They resulted from the classification of all the galaxy spectra in the Sloan Digital Sky Survey data release 7, thus being a comprehensive representation of the galaxy spectra in the local universe. Using the recipe, we give a description of the properties of the gas and the stars that characterize the ASK classes, from those corresponding to passively evolving galaxies, to H II galaxies undergoing a galaxy-wide starburst. The qualitative analysis is found to be in excellent agreement with quantitative analyses of the same spectra. We compare the mean ages of the stellar populations with those inferred using the code STARLIGHT. We also examine the estimated gas-phase metallicity with the metallicities obtained using electron-temperature-based methods. A number of byproducts follow from the analysis. There is a tight correlation between the age of the stellar population and the metallicity of the gas, which is stronger than the correlations between galaxy mass and stellar age, and galaxy mass and gas metallicity. The galaxy spectra are known to follow a one-dimensional sequence, and we identify the luminosity-weighted mean stellar age as the affine parameter that describes the sequence. All ASK classes happen to have a significant fraction of old stars, although spectrum-wise they are outshined by the youngest populations. Old stars are metal-rich or metal-poor depending on whether they reside in passive galaxies or in star-forming galaxies.

Sánchez Almeida, J.; Terlevich, R.; Terlevich, E.; Cid Fernandes, R.; Morales-Luis, A. B.

2012-09-01

194

QUALITATIVE INTERPRETATION OF GALAXY SPECTRA  

SciTech Connect

We describe a simple step-by-step guide to qualitative interpretation of galaxy spectra. Rather than an alternative to existing automated tools, it is put forward as an instrument for quick-look analysis and for gaining physical insight when interpreting the outputs provided by automated tools. Though the recipe is for general application, it was developed for understanding the nature of the Automatic Spectroscopic K-means-based (ASK) template spectra. They resulted from the classification of all the galaxy spectra in the Sloan Digital Sky Survey data release 7, thus being a comprehensive representation of the galaxy spectra in the local universe. Using the recipe, we give a description of the properties of the gas and the stars that characterize the ASK classes, from those corresponding to passively evolving galaxies, to H II galaxies undergoing a galaxy-wide starburst. The qualitative analysis is found to be in excellent agreement with quantitative analyses of the same spectra. We compare the mean ages of the stellar populations with those inferred using the code STARLIGHT. We also examine the estimated gas-phase metallicity with the metallicities obtained using electron-temperature-based methods. A number of byproducts follow from the analysis. There is a tight correlation between the age of the stellar population and the metallicity of the gas, which is stronger than the correlations between galaxy mass and stellar age, and galaxy mass and gas metallicity. The galaxy spectra are known to follow a one-dimensional sequence, and we identify the luminosity-weighted mean stellar age as the affine parameter that describes the sequence. All ASK classes happen to have a significant fraction of old stars, although spectrum-wise they are outshined by the youngest populations. Old stars are metal-rich or metal-poor depending on whether they reside in passive galaxies or in star-forming galaxies.

Sanchez Almeida, J.; Morales-Luis, A. B. [Instituto de Astrofisica de Canarias, E-38205 La Laguna, Tenerife (Spain); Terlevich, R.; Terlevich, E. [Instituto Nacional de Astrofisica, Optica y Electronica, Tonantzintla, Puebla (Mexico); Cid Fernandes, R., E-mail: jos@iac.es, E-mail: abml@iac.es, E-mail: rjt@ast.cam.ac.uk, E-mail: eterlevi@inaoep.mx, E-mail: cid@astro.ufsc.br [Departamento de Fisica-CFM, Universidade Federal de Santa Catarina, P.O. Box 476, 88040-900 Florianopolis, SC (Brazil)

2012-09-10

195

Finite-field method with unbiased polarizable continuum model for evaluation of the second hyperpolarizability of an open-shell singlet molecule in solvents.  

PubMed

The static second hyperpolarizability ? of the complexes composed of open-shell singlet 1,3-dipole molecule involving a boron atom and a water molecule in aqueous phase are investigated by the finite-field (FF) method combined with a standard polarized continuum model (PCM) and with a newly proposed unbiased PCM (UBPCM). On the basis of the comparison with the results calculated by the FF method using the full quantum and the quantum-mechanical/molecular-mechanical and molecular-dynamics (QM/MM-MD) treatments, the present FF-UBPCM method is demonstrated to remedy the artificial overestimation of the ? caused by standard FF-PCM calculations and to well reproduce the FF-QM/MM-MD and FF-full-QM results with much lower costs. © 2013 Wiley Periodicals, Inc. PMID:23913641

Inui, Tomoya; Shigeta, Yasuteru; Okuno, Katsuki; Baba, Takeshi; Kishi, Ryohei; Nakano, Masayoshi

2013-08-01

196

Infrared spectra of urine from cancerous bladders  

Microsoft Academic Search

The infrared spectra of organic constituents of urine from cancerous bladders of some patients were recorded. The spectra of the organic part of the samples were classified into five types according to the bulk constituents. Samples with type A spectra consisted mainly of proteins with only trace amounts of lipids. Their spectra were characterized mainly by the absorption bands of

M. A. Moharram; A. Higazi; A. A. Moharram

1996-01-01

197

FISSION PRODUCT GAMMA RAY SPECTRA  

Microsoft Academic Search

Uranium-235 fission product gamma spectra were calculated for various ; reactor operating histories. An IBM704 digital computer program was coded to ; compute the gamma energy contributed by each fission product gamma ray and to sum ; these results in energy groups. A representative curve showing the decay of ; various energy groups is presented. Comparisons are made with data

1958-01-01

198

Alignment effects in correlation spectra  

SciTech Connect

The structure of nuclei at very high spins can be studied by measuring correlations between ..gamma..-ray energies in the unresolved spectrum emitted. Collective rotations have been shown to produce characteristic features in such correlation spectra. The features produced by the noncollective alignment effects in some high spin Er nuclei are shown here.

Ellegaard, C.; Deleplanque, M.A.; Andersen, O.; Herskind, B.; Stephens, F.S.; Diamond, R.M.; Kluge, H.; Schuck, C.; Shih, S.; Draper, J.E.

1982-03-08

199

Vibrational Spectra of ?-Aminobutyric Acid  

NASA Astrophysics Data System (ADS)

The NIR-FT Raman, FT-IR spectral analysis of ?-Aminobutyric acid (GABA) a simple amino acid is carried out by density functional computations. The vibrational spectra confirm the existence of NH3+ in GABA. Hydroxyl groups H-bonded to the different extents are analysed, supported by computed results.

Suresh, D. M.; Sajan, D.; Laladas, K. P.; Joe, I. Hubert; Jayakumar, V. S.

2008-11-01

200

Modeling of phytochrome absorption spectra.  

PubMed

Phytochromes constitute one of the six well-characterized families of photosensory proteins in Nature. From the viewpoint of computational modeling, however, phytochromes have been the subject of much fewer studies than most other families of photosensory proteins, which is likely a consequence of relevant high-resolution structural data becoming available only in recent years. In this work, hybrid quantum mechanics/molecular mechanics (QM/MM) methods are used to calculate UV-vis absorption spectra of Deinococcus radiodurans bacteriophytochrome. We investigate how the choice of QM/MM methodology affects the resulting spectra and demonstrate that QM/MM methods can reproduce the experimental absorption maxima of both the Q and Soret bands with an accuracy of about 0.15 eV. Furthermore, we assess how the protein environment influences the intrinsic absorption of the bilin chromophore, with particular focus on the Q band underlying the primary photochemistry of phytochromes. PMID:23456980

Falklöf, Olle; Durbeej, Bo

2013-03-01

201

Analysis of molecular emission spectra  

NASA Astrophysics Data System (ADS)

Rich emission spectra are typically observed in the study of post-breakdown plasma phenomena subsequent to laser-induced breakdown of, for example, air. The application of line strengths for various diatomic molecules in non-linear fitting algorithms allows us to infer primarily the temperature at different delay times from optical breakdown. Here we present results of Monte Carlo simulations of different sources of noise in recorded hydroxyl (OH) spectra in order to estimate the reliability and error bars of the fitted set of parameters. Of particular interest is the information content of sections of a measured spectrum for precise evaluations of, for example, rotational and vibrational temperatures. In addition, results are presented of computations by the use of the recently made available code for nonequilibrium air radiation (NEQAIR) which allows us to also estimate number densities of OH and various other species.

Guan, Guoming; Parigger, Christian; Hornkohl, Jim; Lewis, Jim W. L.

1997-11-01

202

Moments of ambient Doppler spectra  

SciTech Connect

The author studied the first four moments (center of mass, standard deviation, skew, and kurtosis) of the Doppler spectra in ambient regions of LLNL-Hughes real aperture radar data collected during WCSEX91--92. The goal was to correlate trends in the moments with wind velocity and direction. Although the center of mass appears to increase when the wind is blowing into the radar antenna, no other conclusions have been drawn from the higher order moments.

Lehman, S.K.

1993-03-23

203

Analysis of molecular emission spectra  

Microsoft Academic Search

Rich emission spectra are typically observed in the study of post-breakdown plasma phenomena subsequent to laser-induced breakdown of, for example, air. The application of line strengths for various diatomic molecules in non-linear fitting algorithms allows us to infer primarily the temperature at different delay times from optical breakdown. Here we present results of Monte Carlo simulations of different sources of

Guoming Guan; Christian Parigger; Jim Hornkohl; Jim W. L. Lewis

1997-01-01

204

Absorption spectra of humic acids  

Microsoft Academic Search

For the purpose of explaining the forming process of soil humic acids, the author determined the absorption spectra of various humic acids. From soils and peats which were pretreated with 5% HCl at 70°C for 30 minutes or from those which were not, humic acids were extracted by treating with 0.5% NaOH at boiling temperature for 30 minutes. In these

Kyoichi Kumada

1955-01-01

205

Transition spectra of dynamical systems  

Microsoft Academic Search

The spectra of ‘stretching numbers’ (or ‘local Lyapunov characteristic numbers’) are different in the ordered and in the chaotic\\u000a domain. We follow the variation of the spectrum as we move from the centre of an island outwards until we reach the chaotic\\u000a domain. As we move outwards the number of abrupt maxima in the spectrum increases. These maxima correspond to

G. Contopoulos; N. Voglis; C. Efthymiopoulos; C. Froeschlé; R. Gonczi; E. Lega; R. Dvorak; E. Lohinger

1997-01-01

206

Prediction of earthquake response spectra  

USGS Publications Warehouse

We have developed empirical equations for predicting earthquake response spectra in terms of magnitude, distance, and site conditions, using a two-stage regression method similar to the one we used previously for peak horizontal acceleration and velocity. We analyzed horizontal pseudo-velocity response at 5 percent damping for 64 records of 12 shallow earthquakes in Western North America, including the recent Coyote Lake and Imperial Valley, California, earthquakes. We developed predictive equations for 12 different periods between 0.1 and 4.0 s, both for the larger of two horizontal components and for the random horizontal component. The resulting spectra show amplification at soil sites compared to rock sites for periods greater than or equal to 0.3 s, with maximum amplification exceeding a factor of 2 at 2.0 s. For periods less than 0.3 s there is slight deamplification at the soil sites. These results are generally consistent with those of several earlier studies. A particularly significant aspect of the predicted spectra is the change of shape with magnitude (confirming earlier results by McGuire and by Irifunac and Anderson). This result indicates that the conventional practice of scaling a constant spectral shape by peak acceleration will not give accurate answers. The Newmark and Hall method of spectral scaling, using both peak acceleration and peak velocity, largely avoids this error. Comparison of our spectra with the Nuclear Regulatory Commission's Regulatory Guide 1.60 spectrum anchored at the same value at 0.1 s shows that the Regulatory Guide 1.60 spectrum is exceeded at soil sites for a magnitude of 7.5 at all distances for periods greater than about 0.5 s. Comparison of our spectra for soil sites with the corresponding ATC-3 curve of lateral design force coefficient for the highest seismic zone indicates that the ATC-3 curve is exceeded within about 7 km of a magnitude 6.5 earthquake and within about 15 km of a magnitude 7.5 event. The amount by which it is exceeded for the 7.5 event is largest in the period range from 0.5 to 2.0 s.

Joyner, W. B.; Boore, David M.

1982-01-01

207

Infrared Spectra of Lunar Soil Analogs.  

National Technical Information Service (NTIS)

The infrared spectra of analogs of lunar soils were investigated to further the development of methodology for interpretation of remotely measured infrared spectra of the lunar surface. The optical constants of dunite, bytownite, augite, ilmenite, and a m...

J. R. Aronson

1977-01-01

208

Power Density Spectra of GRBs  

Microsoft Academic Search

Power density spectra (PDSs) of long gamma-ray bursts (GRBs) provide useful\\u000ainformation on GRBs, indicating their self-similar temporal structure. The best\\u000apower-law PDSs are displayed by the longest bursts (T_90>100 s) in which the\\u000arange of self-similar time scales covers more than 2 decades. Shorter bursts\\u000ahave apparent PDS slopes more strongly affected by statistical fluctuations.\\u000aThe underlying power law

ANDREI M. BELOBORODOV; BORIS E. STERN; ROLAND SVENSSON

2000-01-01

209

Radio spectra of quasars. II  

NASA Astrophysics Data System (ADS)

The second part of a search at 1410 MHz for 230 extragalactic objects from the Southern Hemisphere identified as quasars and listed by Veron-Cetty and Veron (1983) is presented. The 30-m radiotelescope of the Instituto Argentino de Radioastronomia (IAR) was used. From observations at different frequencies, the index and curvature of the corresponding spectra were calculated. The 230 quasars cover a sky area from 06 h to 16 h 40 m in right ascension and from -9.5 to -90 deg in declination. All of them are part of a complete sample of 700 quasars.

Quiniento, Z. M.; Echave, M. M.

1990-06-01

210

Satellite spectra of heliumlike nickel  

SciTech Connect

Spectra of heliumlike nickel, NiXXVII, have been observed from Tokamak Fusion Test Reactor (TFTR) plasmas with a high resolution crystal spectrometer. The experimental arrangement permits simultaneous observation of the heliumlike resonance line, the intercombination and forbidden lines, and all the associated satellites due to transitions 1s/sup 2/nl - 1s2l'nl'' with N greater than or equal to 2. Relative wavelengths and line intensities can thus be determined very accurately. The observed spectral data are in good agreement with results from the present Hartree-Fock-Slater atomic model calculations and predictions from the Z-expansion method.

Hsuan, H.; Bitter, M.; Hill, K.W.; von Goeler, S. Grek, B.; Johnson, D.; Johnson, L.C.; Sesnic, S.; Bhalla, C.P.; Karim, K.R.

1987-02-01

211

Exciton spectra of semiconductor clusters  

SciTech Connect

The band gaps and exciton energies of CdS and GaP clusters are calculated for the first time using pseudopotentials. The calculated exciton energies of CdS over a wide range of cluster sizes are in excellent agreement with experiment. Furthermore, the exciton states of clusters with zinc-blende and hexagonal lattices are similar in large clusters, but differ dramatically in small clusters. Finally, the spectra of small GaP clusters shift to red, instead of to the blue, with decreasing cluster size. These effects provide novel ways of tuning the optical properties of clusters.

Rama Krishna, M.V.; Friesner, R.A. (Department of Chemistry, Columbia University, New York, New York (USA))

1991-07-29

212

Atlas of Chandra Hot Star Spectra  

Microsoft Academic Search

The Chandra Observatory is obtaining transmission grating spectra of many hot stars. We present a prototype of Chandra Spectral Atlas of Hot Stars, which will include publicly available grating spectra of WR, O, and B stars of representative spectral classes. Currently, there are 20 HETG spectra of 14 unique objects in the archives which will all be public within a

N. R. Evans; J. Slavin; V. Kashyap; J. Nichols; E. Schlegel; M. Yukita

2002-01-01

213

Infrared Spectra of Dilute Solid Solutions  

Microsoft Academic Search

The infrared spectra of polyatomic ions in dilute solid solution reflect interactions of the vibrational modes with the lattice environment. The spectra are usually characterized by very narrow bandwidths, and by frequency shifts and changes in absorption intensities which depend upon the host lattice. We have examined the spectra of a number of ions in solid solution in alkali halides.

H. W. Morgan; P. A. Staats

1962-01-01

214

Quantitative characteristics of methane's infrared spectra  

Microsoft Academic Search

FTIR spectra have been widely used in quantitative analyses of mixed gases. Although Beer's Law regulates the relationships between absorbency and the product of concentration and path length, its deviations have been found rather complicated. Here we present the complexity of quantitative relationships between methane's infrared spectra and concentrations and resolutions. Measurements of the same methane sample's spectra under different

Xian-yong Liu; Li-ping Shang; Hong-lei Li

2005-01-01

215

Mixing Model Analysis of Telescopic Lunar Spectra.  

National Technical Information Service (NTIS)

We have analyzed very high quality reflectance spectra of the lunar surface from the University of Hawaii lunar spectral data collection using a spectral mixing model. The spectra analyzed are those of 45 mare sites and 75 highland sites. The spectra were...

P. G. Lucey B. C. Clark B. R. Hawke

1993-01-01

216

Fine expression profiling of full-length transcripts using a size-unbiased cDNA library prepared with the vector-capping method.  

PubMed

Recently, we have developed a vector-capping method for constructing a full-length cDNA library. In the present study, we performed in-depth analysis of the vector-capped cDNA library prepared from a single type of cell. As a result of single-pass sequencing analysis of 24,000 clones randomly isolated from the unamplified library, we identified 19,951 full-length cDNA clones whose intactness was confirmed by the presence of an additional G at their 5' end. The full-length cDNA content was >95%. Mapping these sequences to the human genome, we identified 4,513 transcriptional units that include 36 antisense transcripts against known genes. Comparison of the frequencies of abundant clones showed that the expression profiles of different libraries, including the distribution of transcriptional start sites (TSSs), were reproducible. The analysis of long-sized cDNAs showed that this library contained many cDNAs with a long-sized insert up to 11,199 bp of golgin B, including multiple slicing variants for filamin A and filamin B. These results suggest that the size-unbiased full-length cDNA library constructed using the vector-capping method will be an ideal resource for fine expression profiling of transcriptional variants with alternative TSSs and alternative splicing. PMID:18487259

Oshikawa, Mio; Sugai, Yoshiko; Usami, Ron; Ohtoko, Kuniyo; Toyama, Shigeru; Kato, Seishi

2008-05-16

217

Magnetar spectra and twisted magnetospheres  

NASA Astrophysics Data System (ADS)

The huge potential drop between the footpoints of the closed field lines in the twisted magnetospheres of magnetars may accelerate electrons up to very high energies, ? ? 106. On the other hand, the comparison between the observed spectra of magnetars and spectra obtained by accurate theoretical models seems to favor of a picture in which the magnetosphere is filled by “slow” electrons (v ? 0.8c), rather than by ultra-relativistic particles.Actually, two different processes may limit the effective velocity of charges in the innermost part of the magnetosphere, both related to the resonant behavior of the Compton scattering in strong magnetic field. Near the stellar surface, where the magnetic field B exceeds the quantum limit BQ ? 4.4 × 1013 G, scattering between fast electrons and ˜1 keV seed photons generates high-energy gamma rays that immediately convert to electron/positron pairs via one-photon pair production. This runaway process limits the value of ? to the threshold value for pair production ? ? 1000. At larger distance the magnetic field weakens, and pair creation is strongly depressed for the impossibility of resonant scattering to generate high-energy photons. We discuss the possibility that, in the intermediate region 5R? ? r ? 20R? (with R? = 10 km), intense Compton losses are effective in reducing the acceleration of electrons even in presence of a very high potential drop.

Nobili, Luciano; Turolla, Roberto; Zane, Silvia

2011-04-01

218

Synthetic spectra of CP stars compared with UVES spectra  

NASA Astrophysics Data System (ADS)

Results from spectral analyses of some HgMn stars observed with UVES at high resolution and high S/N are available on-line in the form of plots showing superimposed observed and LTE-computed spectra. The material is available on line at http://wwwuser.oat.ts.astro.it/castelli/stars.html. The ranges studied are divided into 6Å wide intervals. The plots have identifications, excitation potential of the lower level, and predicted line intensities written above the lines. Complete analyses covering the 3050 - 9500Å region have been performed for two stars, HD175640 and HR6000. The on-line plots show the quality of the agreement between observations and computations and can be used as a template for other stars of the same spectral type. For instance, HD175640 and HR6000 are excellent examples of a very overabundant Mn ([+2.4]) star and of a very overabundant Fe ([+0.7]) star, respectively.

Castelli, F.; Hubrig, S.

2008-04-01

219

Intensity Spectra Versus Response Spectra: Basic Concepts and Applications  

NASA Astrophysics Data System (ADS)

This paper begins with a critical assessment of the concept of macroseismic intensity, on which traditional scales, such as MSK and EMS, are based. The main shortcoming identified is the model's failure to consider the spectral features of ground motion. This omission may lead to erroneous seismic zonation, as shown in the paper. As a result, the model is of little interest to engineers who must design and build safe structures while adopting economical solutions. The paper presents a way to radically improve this situation. The starting point for this approach was the experience of the destructive Vrancea earthquake of 1977.03.04, which made it clear that intensity appears to be different for structures having natural periods pertaining to different spectral domains. The solution proposed to the shortcomings of the traditional intensity concept is postulated on a system of analytical expressions, covering definitions of global intensities, of intensities related to oscillation frequency and of intensities related to a definite spectral band. The latter definition lies at the basis of a definition of discrete intensity spectra. Illustrative applications are presented, in relation to global intensities and to discrete intensity spectra. We then analyze an illustrative case in which the use of traditional macroseismic survey techniques led to erroneous seismic zonation. Finally, some conclusions and recommendations are presented. Based on the authors' long-term experience, we strongly recommend close interaction between seismologists and engineers in working groups and joint projects targeted on radical improvement of the basic concepts of seismic intensity and of specific analysis procedures.

Sandi, Horea; Borcia, Ioan Sorin

2011-01-01

220

Clustering Millions of Tandem Mass Spectra  

PubMed Central

Summary Tandem mass spectrometry (MS/MS) experiments often generate redundant datasets containing multiple spectra of the same peptides. Clustering of MS/MS spectra takes advantage of this redundancy by identifying multiple spectra of the same peptide and replacing them with a single representative spectrum. Analyzing only representative spectra results in significant speed-up of MS/MS database searches. We present an efficient clustering approach for analyzing large MS/MS datasets (over ten million spectra) with a capability to reduce the number of spectra submitted to further analysis by an order of magnitude. The MS/MS database search of clustered spectra results in fewer spurious hits to the database and increases number of peptide identifications as compared to regular non-clustered searches. Our open source software MS-Clustering is available for download at http://peptide.ucsd.edu or can be run online at http://proteomics.bioprojects.org/MassSpec.

Frank, Ari M.; Bandeira, Nuno; Shen, Zhouxin; Tanner, Stephen; Briggs, Steven P.; Smith, Richard D.; Pevzner, Pavel A.

2008-01-01

221

Bayesian analysis of RHESSI spectra  

NASA Astrophysics Data System (ADS)

We use Bayesian posterior analysis to determine credible intervals to the parameter values of flare models of RHESSI data. Two flare spectra, from the 23 July 2002 and 19 January 2005 events are considered. The Bayesian credible interval (an upper and lower limit to a parameter value, plus the probability that the true value lies between those limits) is compared to the standard error found using conventional analysis techniques. Of particular interest is the low energy cutoff. The Bayesian approach allows us to quote an upper limit to the low energy cutoff with the probability that the low energy cutoff is below that upper limit. The implications of a Bayesian analysis on our understanding of these flare events are discussed. Extensions to the current approach are also discussed.

Ireland, J.; Holman, G.; Dennis, B. R.; Tolbert, A. K.; Schwartz, R. A.

2009-12-01

222

Background estimation in experimental spectra  

SciTech Connect

A general probabilistic technique for estimating background contributions to measured spectra is presented. A Bayesian model is used to capture the defining characteristics of the problem, namely, that the background is smoother than the signal. The signal is allowed to have positive and/or negative components. The background is represented in terms of a cubic spline basis. A variable degree of smoothness of the background is attained by allowing the number of knots and the knot positions to be adaptively chosen on the basis of the data. The fully Bayesian approach taken provides a natural way to handle knot adaptivity and allows uncertainties in the background to be estimated. Our technique is demonstrated on a particle induced x-ray emission spectrum from a geological sample and an Auger spectrum from iron, which contains signals with both positive and negative components. (c) 2000 The American Physical Society.

Fischer, R. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association D-85740 Garching bei Muenchen, (Germany); Hanson, K. M. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association D-85740 Garching bei Muenchen, (Germany); Los Alamos National Laboratory, MS P940, Los Alamos, New Mexico 87545 (United States); Dose, V. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association D-85740 Garching bei Muenchen (Germany); Linden, W. von der [Institut fuer Theoretische Physik, Technische Universitaet Graz, Petersgasse 16, A-8010 Graz, (Austria)

2000-02-01

223

Sampling ENDL Watt Fission Spectra  

SciTech Connect

All of the fission spectra in the Evaluated Nuclear Data Library, ENDL [1], are defined by a simple analytical function: a Watt spectrum [2], W(a,b,E') = C*Exp[-a*E']*Sinh[(b*E'){sup 1/2}]. Where the normalization, C, is given by, C = [{pi}b/4a]{sup 1/2} Exp[b/4a]/a. The coefficients a and b vary from one isotope to another and also vary weakly with the incident neutron energy. Here E' is the secondary energy, i.e., the energy at which the fission neutrons are emitted. In ENDL energy units of MeV for incident neutron energies between 0 and 20 MeV, in all cases b is very close to 1.0, and a varies over a rather small range near 1.0. Currently there are 38 fissionable isotopes in ENDL. For each of these isotopes I have parameterized a as a simple function of the incident neutron energy, and I treat b as always equal to unity. The values of these parameters are available to TART users as part of the TART CD package [3]. This parameterization coupled with the general Watt sampling method described below results in a very fast and accurate method of sampling all of the fission spectra in ENDL. In all cases I select the fissioning isotope, define a based on isotope and incident neutron energy, and then use the below described method to sample the energy E' of a neutron emitted due to fission.

Cullen, D E

2004-04-01

224

Unbiased Mutagenesis of MHV68 LANA Reveals a DNA-Binding Domain Required for LANA Function In Vitro and In Vivo  

PubMed Central

The Latency-Associated Nuclear Antigen (LANA), encoded by ORF73, is a conserved gene among the ?2-herpesviruses (rhadinoviruses). The Kaposi's Sarcoma-Associated Herpesvirus (KSHV) LANA is consistently expressed in KSHV-associated malignancies. In the case of the rodent ?2-herpesvirus, murine gammaherpesvirus 68 (MHV68), the LANA homolog (mLANA) is required for efficient virus replication, reactivation from latency and immortalization of murine fetal liver-derived B cells. To gain insights into mLANA function(s), knowing that KSHV LANA binds DNA and can modulate transcription of a variety of promoters, we sought out and identified a mLANA-responsive promoter which maps to the terminal repeat (TR) of MHV68. Notably, mLANA strongly repressed activity from this promoter. We extended these analyses to demonstrate direct, sequence-specific binding of recombinant mLANA to TR DNA by DNase I footprinting. To assess whether the DNA-binding and/or transcription modulating function is important in the known mLANA phenotypes, we generated an unbiased library of mLANA point mutants using error-prone PCR, and screened a large panel of mutants for repression of the mLANA-responsive promoter to identify loss of function mutants. Notably, among the mutant mLANA proteins recovered, many of the mutations are in a predicted EBNA-1-like DNA-binding domain. Consistent with this prediction, those tested displayed loss of DNA binding activity. We engineered six of these mLANA mutants into the MHV68 genome and tested the resulting mutant viruses for: (i) replication fitness; (ii) efficiency of latency establishment; and (iii) reactivation from latency. Interestingly, each of these mLANA-mutant viruses exhibited phenotypes similar to the mLANA-null mutant virus, indicating that DNA-binding is critical for mLANA function.

Paden, Clinton R.; Forrest, J. Craig; Tibbetts, Scott A.; Speck, Samuel H.

2012-01-01

225

CHaMP@Spitzer: The Formation and Early Evolution of Star Clusters in a Large Unbiased Sample of Dense Gas Clumps  

NASA Astrophysics Data System (ADS)

The Galactic Census of High- and Medium-mass Protostars (CHaMP) is a large, unbiased, and panchromatic survey of the formation and early evolution of stars and star clusters covering 20 by 6 deg. of the Galactic Plane. The survey is based on a complete sample of ~300 dense (HCO+ J=1-0 emitting) gas clumps, selected by a recursive mapping of the peaks of 12CO, 13CO, and C18O emission, and then mapped by the Mopra radio telescope in a multitude of molecular transitions. Thus, for the first time we have a full census of the dense gas structures in a large volume of the Milky Way. The goal of this proposal is to use Warm Spitzer to characterize the star formation activity in this entire sample, probing the complete range of dense gas environments. We can resolve the formation of individual stars, but at the same time the full dataset will give us a measure of the global star formation activity of a large portion of the Milky Way, and the range of star formation efficiencies exhibited by molecular clouds. In particular, Spitzer data will: 1. Yield a complete census of any Young Stellar Objects in each clump down to about a solar mass, including their spatial distributions. 2. Combined with other infrared data, allow systematic measurements of the properties of any embedded clusters, including luminosity and mass functions, broad-band spectral classification, protostellar and disk fractions, outflow indicators, and how these vary with cluster mass and density. 3. Combined with mm data, permit a detailed comparison of the embedded stellar populations with their natal dense gas to derive star formation efficiencies and feedback effects.

Barnes, Peter; Lada, Elizabeth; Smith, Nathan; Tan, Jonathan; Romita, Krista; O'Dougherty, Stefan; Ma, Bo; Ryder, Stuart; Hopkins, Andrew

2011-05-01

226

DUSC: Dimensionality Unbiased Subspace Clustering  

Microsoft Academic Search

To gain insight into today's large data resources, data mining provides automatic aggregation techniques. Clus- tering aims at grouping data such that objects within groups are similar while objects in different groups are dissimilar. In scenarios with many attributes or with noise, clusters are often hidden in subspaces of the data and do not show up in the full dimensional

Ira Assent; Ralph Krieger; Emmanuel Müller; Thomas Seidl

2007-01-01

227

The Suzaku View of the Swift/BAT Active Galactic Nuclei. II. Time Variability and Spectra of Five "Hidden" Active Galactic Nuclei  

NASA Astrophysics Data System (ADS)

The fraction of Compton-thick sources is one of the main uncertainties left in understanding the active galactic nucleus (AGN) population. The Swift Burst Alert Telescope (BAT) all-sky survey for the first time gives us an unbiased sample of AGNs for all but the most heavily absorbed sources N H > 1025 cm-2). Still, the BAT spectra (14-195 keV) are time averaged over months of observations and therefore hard to compare with softer spectra from the Swift XRT or other missions. This makes it difficult to distinguish between Compton-thin and Compton-thick models. With Suzaku, we have obtained simultaneous hard (>15 keV) and soft (0.3-10 keV) X-ray spectra for five Compton-thick candidate sources. We report on the spectra and a comparison with the BAT and earlier XMM observations. Based on both flux variability and spectral shape, we conclude that these hidden sources are not Compton thick. We also report on a possible correlation between excess variance and Swift BAT luminosity from the 16 day binned light curves, which holds true for a sample of both absorbed (four sources), unabsorbed (eight sources), and Compton-thick (Circinus) AGNs, but is weak in the 64 day binned BAT light curves.

Winter, Lisa M.; Mushotzky, Richard F.; Terashima, Yuichi; Ueda, Yoshihiro

2009-08-01

228

Infrared spectra of organic beryllium complexes  

Microsoft Academic Search

1.The same bands are always observed in the 700–1300 cm”' region of the infrared spectra of coordination compounds with the same ligand but different metals, since the bands come from ligand vibrations.2.A wide and intense band at 830 cm”-1 is observed in the infrared spectra of all the beryllium coordination compounds studied. This band is absent from the spectra of

V. V. Korshak; L. I. Komarova; T. A. Sidorov

1962-01-01

229

Spectra of accretion discs around white dwarfs  

NASA Astrophysics Data System (ADS)

We present the spectra of accretion discs around white dwarfs calculated with an improved and updated version of Shaviv and Wehrse [Shaviv, G., Wehrse, R., 1991. A&A 251, 117] model. The new version includes line opacities and convective energy transport and can be used to calculate the spectra of hot discs in bright systems (nova-like variables or dwarf novae in outburst) as well as the spectra of cold accretion discs in quiescent dwarf novae.

Idan, Irit; Lasota, Jean-Pierre; Hameury, Jean-Marie; Shaviv, Giora

2008-05-01

230

Infrared spectra of thyroid tumor tissues  

NASA Astrophysics Data System (ADS)

We used infrared spectroscopy methods to study thyroid tumor tissues removed during surgery. The IR spectra of the surgical material are compared with data from histological examination. We show that in malignant neoplasms, the spectra of proteins in the region of C=O vibrations are different from the spectra of these substances in benign tumors and in tissues outside the pathological focus at a distance >1 cm from the margin of the tumor. The differences in the spectra are due to changes in the supermolecular structure of the proteins, resulting from rearrangement of the system of hydrogen bonds. We identify the spectral signs of malignant pathologies.

Tolstorozhev, G. B.; Skornyakov, I. V.; Butra, V. A.

2010-07-01

231

Energetic electron spectra in Saturn's plasma sheet  

NASA Astrophysics Data System (ADS)

The differential spectra of energetic electrons (27-400 keV) in Saturn's plasma sheet can be characterized by power law or kappa distributions. Using all available fluxes from 2005 to 2010, fits to these distributions reveal a striking and consistent pattern of radial dependence in Saturn's plasma sheet (?z? < 1 RS = 60,268 km). The electron spectral indices show harder spectra at large radial distances (20-30 RS), softer spectra at middle radial distances (10-20 RS), and very steep spectra inside the orbit of Rhea (˜8.5 RS). The dayside spectra are somewhat harder than the nightside spectra outside the orbit of Titan (˜20 RS), although there is no local time dependence inside ˜10 RS. This spectral behavior exhibited essentially no dependence on pitch angle and remained remarkably constant throughout the Cassini mission. Inward of about 10 RS, the presence of the electron radiation belts and losses of lower-energy electrons to the gas and grain environment give rise to the very hard spectra in the inner magnetosphere, while the hard spectra in the outer magnetosphere may derive from auroral acceleration at high latitudes. The gradual softening of the spectra from 20 to 10 RS is explained by inward radial diffusion.

Carbary, J. F.; Paranicas, C.; Mitchell, D. G.; Krimigis, S. M.; Krupp, N.

2011-07-01

232

On temporal spectra of scintillometers  

NASA Astrophysics Data System (ADS)

Clifford (1971) derived expressions for the real and imaginary part of the temporal spectra W(f) for spherical waves propagating through the atmosphere. To a good approximation, the transmitter of a Millimeter-Wave Scintillometer (MWS) can be regarded as a point source and thus Clifford's theory is applicable to a MWS. Nieveen et al. (1998) extended Clifford's theory to large aperture scintillometers (LAS). In both cases a so called corner frequency, fc , can be defined. For frequencies smaller than fc , the real part of W(f) is approximately constant at Wplateau, whereas for f > fc , the real part of W(f) is proportional to f-8?3 for the MWS. It is noted that Wplateau is inversely proportional to the cross wind uc and that fc is proportional to uc, therefore the integral of W(f) over all fis independent of uc; however, this applies for the case where the cross wind does not vary along the path. During a field experiment carried out in mid-summer 2006 at Sheepdrove Organic Farm, UK, over mixed agricultural land use and complex topography, W(f) was measured by a 94 GHz MWS. There were contrasting cool-windy and hot-convective weather conditions during the experiment. With these data the Clifford theory will be validated.

Evans, J. G.; de Bruin, H. A. R.

2009-09-01

233

XSPECT, estimation of the angular power spectrum by computing cross-power spectra with analytical error bars  

NASA Astrophysics Data System (ADS)

We present XSPECT, a method to obtain estimates of the angular power spectrum of the cosmic microwave background (CMB) temperature anisotropies including analytical error bars developed for the Archeops experiment. Cross-power spectra are computed from a set of maps and each of them is in itself an unbiased estimate of the power spectrum as long as the detector noises are uncorrelated. Then, the cross-power spectra are combined into a final temperature power spectrum with error bars analytically derived from the cross-correlation matrix. This method presents three main useful properties: (1) no estimation of the noise power spectrum is needed; (2) complex weighting schemes including sky covering and map noise properties can be easily taken into account, and corrected for, for each input map; and (3) error bars are quickly computed analytically from the data themselves with no Monte Carlo simulations involved. XSPECT also permits the study of common fluctuations between maps from different sky surveys such as CMB, Sunyaev-Zel'dovich effect or mass fluctuations from weak lensing observations.

Tristram, M.; Macías-Pérez, J. F.; Renault, C.; Santos, D.

2005-04-01

234

An Immunogenetic Approach to Spectra Recognition  

Microsoft Academic Search

The paper describes an immunogenetic approach to recognize spectra for chemical analysis. In particular, an immunological model for chemical reactions is introduced in which a population of specialists for each of the possible products was evolved using a genetic algorithm. Accordingly, a small well-trained specialist library is established and tested their recognition ability with real dataset (Raman Spectra). Our experiments

Dipankar Dasgupta; Yuehua Cao; Congjun Yang

1999-01-01

235

The Science of Light: Stellar Spectra  

NSDL National Science Digital Library

This web page, part of the Annenberg Media Teachers' Labs, enables visitors to analyze the spectrum of a star and determine its composition. The site displays spectra of various elements and then shows a stellar spectrum, so the user can match spectral lines and identify elements in the star. Several samples of stellar spectra are provided.

2007-07-25

236

Model independent evaluation of overlapped Mossbauer spectra  

Microsoft Academic Search

A calculation scheme for the evaluation of hyperfine field distributions from overlapped Mossbauer spectra is being proposed. A different procedure for the same purpose has been used by Window (1971). Based on simulated Mossbauer spectra both methods are applied for three special cases. The obtained results are compared and discussed.

J. Hesse; A. Rubartsch

1974-01-01

237

Infrared Spectra of Transition Metal Alkoxides.  

National Technical Information Service (NTIS)

The infrared spectra of a number of transition metal isopropoxides and tetra tertiary butoxides were obtained from 5000 cm-1 to 285 cm-1 for the first time. The spectra were compared to existing infrared data on these classes of compounds. Characteristic ...

C. T. Lynch K. S. Mazdiyasni J. S. Smith W. J. Crawford

1964-01-01

238

Automated training sample labeling using laboratory spectra  

Microsoft Academic Search

This paper presents a method for automatically labeling training samples in mineral identification problems. A previous work showed that an experienced human operator can successfully identify training samples by visually comparing the strong absorption features of the laboratory spectra to those of the adjusted remotely sensed spectra. However, it is obviously a time-consuming process. The purpose of this research is

Pifuei Hsieh; D. A. Landgrebe

1996-01-01

239

PCA: Principal Component Analysis for spectra modeling  

NASA Astrophysics Data System (ADS)

The mid-infrared spectra of ultraluminous infrared galaxies (ULIRGs) contain a variety of spectral features that can be used as diagnostics to characterize the spectra. However, such diagnostics are biased by our prior prejudices on the origin of the features. Moreover, by using only part of the spectrum they do not utilize the full information content of the spectra. Blind statistical techniques such as principal component analysis (PCA) consider the whole spectrum, find correlated features and separate them out into distinct components. This code, written in IDL, classifies principal components of IRS spectra to define a new classification scheme using 5D Gaussian mixtures modelling. The five PCs and average spectra for the four classifications to classify objects are made available with the code.

Hurley, Peter D.; Oliver, Seb; Farrah, Duncan; Wang, Lingyu; Efstathiou, Andreas

2012-07-01

240

The Optically Unbiased GRB Host (TOUGH) Survey. VI. Radio Observations at z <~ 1 and Consistency with Typical Star-forming Galaxies  

NASA Astrophysics Data System (ADS)

The objective of this paper is to determine the level of obscured star formation activity and dust attenuation in a sample of gamma-ray burst (GRB) hosts, and to test the hypothesis that GRB hosts have properties consistent with those of the general star-forming galaxy populations. We present a radio continuum survey of all z < 1 GRB hosts in The Optically Unbiased GRB Host (TOUGH) sample supplemented with radio data for all (mostly pre-Swift) GRB-SN hosts discovered before 2006 October. We present new radio data for 22 objects and have obtained a detection for three of them (GRB 980425, 021211, 031203; none in the TOUGH sample), increasing the number of radio-detected GRB hosts from two to five. The star formation rate (SFR) for the GRB 021211 host of ~825 M ? yr-1, the highest ever reported for a GRB host, places it in the category of ultraluminous infrared galaxies. We found that at least ~63% of GRB hosts have SFR < 100 M ? yr-1 and at most ~8% can have SFR > 500 M ? yr-1. For the undetected hosts the mean radio flux (<35 ?Jy 3?) corresponds to an average SFR < 15 M ? yr-1. Moreover, >~ 88% of the z <~ 1 GRB hosts have ultraviolet dust attenuation A UV < 6.7 mag (visual attenuation AV < 3 mag). Hence, we did not find evidence for large dust obscuration in a majority of GRB hosts. Finally, we found that the distributions of SFRs and A UV of GRB hosts are consistent with those of Lyman break galaxies, H? emitters at similar redshifts, and of galaxies from cosmological simulations. The similarity of the GRB population with other star-forming galaxies is consistent with the hypothesis that GRBs, a least at z <~ 1, trace a large fraction of all star formation, and are therefore less biased indicators than once thought. Based on observations collected at the European Southern Observatory, Paranal, Chile (ESO Large Programme 177.A-0591), the Australian Telescope Compact Array, the Giant Metrewave Radio Telescope, the Very Large Array, and the Westerbork Synthesis Radio Telescope.

Micha?owski, M. J.; Kamble, A.; Hjorth, J.; Malesani, D.; Reinfrank, R. F.; Bonavera, L.; Castro Cerón, J. M.; Ibar, E.; Dunlop, J. S.; Fynbo, J. P. U.; Garrett, M. A.; Jakobsson, P.; Kaplan, D. L.; Krühler, T.; Levan, A. J.; Massardi, M.; Pal, S.; Sollerman, J.; Tanvir, N. R.; van der Horst, A. J.; Watson, D.; Wiersema, K.

2012-08-01

241

Vibration Spectra and Molecular Structure VIII. Absorption Spectra of Light and Heavy Phenol and Aniline Vapors  

Microsoft Academic Search

The near infra-red spectra of light and heavy phenol and aniline vapors have been obtained with a rocksalt spectrometer. Comparisons have been made between the spectra of the light compounds as found in various phases, and an interpretation of certain changes occurring in the spectrum of phenol is suggested. The spectra of the heavy compounds have suggested certain assignments, such

V. Williams; R. Hofstadter; R. C. Herman

1939-01-01

242

Estimation of vertical sea level muon energy spectra from the latest primary cosmic ray elemental spectra  

Microsoft Academic Search

The directly measured elemental spectra of primary cosmic rays obtained from Webber et al., Seo et al., Menn et al., Ryan et al. and experiments like JACEE, CRN, SOKOL, RICH on P, He, CNO, Ne-S and Fe have been considered to estimate the vertical sea level muon energy spectra. The primary elemental energy spectra of P, He, CNO, Ne-S and

M. Mitra; N. H. Molla; D. P. Bhattacharyya

2001-01-01

243

Handbook of Monochromatic XPS Spectra, Semiconductors  

NASA Astrophysics Data System (ADS)

This handbook is one of three containing an invaluable collection of research grade XPS Spectra. Each handbook concentrates on a specific family of materials (the elements and their native oxides, semiconductors and polymers) and is entirely self-contained. The introductory section to each handbook includes comprehensive information about the XPS instrument used, the materials and the advanced methods used to collect the spectra. Energy resolution settings, instrument characteristics, energy referencing methods, traceability, energy scale calibration details and transmission function are all reported. Among the many valuable features included in each of these handbooks are: ? All spectra were measured by using AlK monochromatic X-rays ? All spectra were collected in a self-consistent manner to maximise data reliability and quality ? All peaks in the wide spectra are fully annotated and accompanied by detailed atom % tables that report BEs for each of the labelled peaks ? Each high-energy resolution spectrum is peak-fitted and accompanied by detailed tables containing binding energies, FWHMs and relative percentages. In this volume 'Semiconductors' are contained XPS Spectra from a wide range of semiconductive materials and related materials, a rare tool for scientists and analysts in this area. Exclusive features of this volume include: ? Binding energies are accurate to +/- 0.08eV ? Charge compensation was done with a flood-gun mesh-screen system ? Valence band spectra document the occupied density of states (DOS) and the fundamental electronic nature of the semi-conductive materials analysed ? Analyses were done: "as received", "freshly fractured in air", "ion etched" and "chemically treated" ? Alphabetically organised by chemical abbreviations for ease of locating each material This handbook is an invaluable reference for materials scientists and electrical engineers in industry, academia and government laboratories interested in the analysis of semiconductors. Also Available; Handbook of Monochromatic XPS Spectra: The Elements and Their Native Oxides Handbook of Monochromatic XPS Spectra: Polymers and Polymer Damage

Crist, B. Vincent

2000-10-01

244

Modelling the Spectra of (BAL)QSOs  

NASA Astrophysics Data System (ADS)

We have embarked upon a project to model the UV spectra of BALQSOs using a Monte Carlo radiative transfer code previously validated through modelling of the winds of cataclysmic variable stars (e.g., Noebauer et al. 2010). We intend to use the simulations to investigate the plausibility of geometric unification (e.g., Elvis 2000) of the different classes of QSO. Here we introduce the code, and present some initial results. These demonstrate that for reasonable geometries and mass loss rates we are able to produce synthetic spectra which reproduce the important features of observed BALQSO spectra.

Higginbottom, N.; Long, K. S.; Knigge, C.; Sim, S. A.

2012-08-01

245

Simulation of x-ray fluorescence spectra  

SciTech Connect

A method for simulating x-ray fluorescence (XRF) spectra in hybrid densitometry is presented. This technique allows simulation of XRF spectra for solutions with arbitrary concentrations of special nuclear material and minor actinides excited by an x-ray generator. Spectra for mixed uranium and plutonium solutions with U/Pu ratios ranging from 100 to 1 have been generated. This range of ratios applies to most solutions found in plutonium reprocessing plants. XRF simulation can provide important data for estimating instrument precision, evaluating analysis techniques, and training system operators. Applications of XRF simulation in the development of the Los Alamos Hybrid K-Edge/XRF Densitometer system are described.

Collins, M.L.; Hsue, S.T. [Los Alamos National Lab., NM (United States); Gunnink, R. [Gunnink (R.), Fremont, CA (United States)

1996-09-01

246

Cosmic-Ray Spectra in Interstellar Space  

SciTech Connect

At energies below {approx}300 MeV/nuc our knowledge of cosmic-ray spectra outside the heliosphere is obscured by the energy loss that cosmic rays experience during transport through the heliosphere into the inner solar system. This paper compares measurements of secondary electron-capture isotope abundances and cosmic-ray spectra from ACE with a simple model of interstellar propagation and solar modulation in order to place limits on the range of interstellar spectra that are compatible with both sets of data.

Mewaldt, R.A.; Cummings, A.C.; Davis, A.J.; Leske, R.A.; Stone, E.C. [California Institute of Technology, Pasadena, CA 91126 (United States); Wiedenbeck, M.E. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena CA 91190 (United States); Scott, L.M.; Binns, W.R.; Israel, M.H. [Department of Physics, Washington University, St. Louis MO. 63105 (United States); Rosenvinge, T.T. von [NASA/Goddard Space Flight Center, Greenbelt MD 20771 (United States)

2004-09-15

247

Vibrational spectra and structure of isopropylbenzene  

NASA Astrophysics Data System (ADS)

Infrared spectra (4000-400 cm -1) and Raman spectra (1700-40 cm -1) of the liquid and two crystalline solids of isopropylbenzene (cumene) and isopropylbenzene-d 12 have been recorded. The spectra indicate that in the liquid and crystalline solids isopropylbenzene exists in planar conformation only (C sbnd H bond is in the plane of the benzene ring). An assignment of the observed band wave numbers both isopropylbenzene and isopropylbenzene-d 12 is discussed by comparison with normal mode wave numbers and IR intensities calculated from ab initio 6-31G (d) force fields.

Fishman, A. I.; Noskov, A. I.; Remizov, A. B.; Chachkov, D. V.

2008-12-01

248

SCALING PROPERTIES OF THE TRANSVERSE MASS SPECTRA.  

SciTech Connect

Motivated from the formation of an initial state of gluon-saturated matter, we discuss scaling relations for the transverse mass spectra at BNL's Relativistic Heavy-Ion Collider (RHIC). We show on linear plots, that the transverse mass spectra for various hadrons can be described by an universal function in m{sub t}. The transverse mass spectra for different centralities can be rescaled into each other. Finally, we demonstrate that m{sub t}-scaling is also present in proton-antiproton collider data and compare it to m{sub t}-scaling at RHIC.

SCHAFFNER-BIELICH,J.; KHARZEEV,D.; MCLERRAN,L.; VENUGOPALAN,R.

2002-01-13

249

IRAS low-resolution spectra of galaxies  

SciTech Connect

The spectra of external galaxies are selected and extracted from the IRAS LRS database. Twenty-one objects present viable spectra. One is a peculiar star-forming E-S0 galaxy. The remainder are all starburst or H II region galaxies. Their average spectrum demonstrates the importance of the PAH emission bands in the 8-23-micron region and reinforces the conclusion reached from ground-based spectra, that there is a strong correlation between the PAH bands and the starburst or H II region character of a galaxy. 32 refs.

Cohen, M.; Volk, K. (Jamieson Science and Engineering, Inc., Scotts Valley (USA) California Univ., Berkeley (USA) NASA, Ames Research Center, Moffett Field (USA) SETI Institute, Mountain View, CA (USA))

1989-11-01

250

Spectra of KIC10661783 (Lehmann+, 2013)  

NASA Astrophysics Data System (ADS)

In 2010, we obtained 26 high-resolution spectra of KIC 10661783 in seven almost consecutive nights using the Coude-echelle spectrograph at the 2-m telescope of the Thueringer Landessternwarte Tautenburg. The spectra have a resolving power of 64000 and cover the wavelength range 470-740nm. The exposure time was 30 min and the spectra have a signal-to-noise ratio of 90 on average. They were reduced using standard ESO-MIDAS packages and a routine for the calibration of the instrumental radial velocity zero-point using O2 telluric lines. (2 data files).

Lehmann, H.; Southworth, J.; Tkachenko, A.; Pavlovski, K.

2013-08-01

251

Interpretation of High-z SN Spectra  

NASA Astrophysics Data System (ADS)

We present several quality spectra of high-redshift Type Ia Supernovae (SNe Ia) observed over the past 7 years by the Supernova Cosmology Project. These spectra are first and foremost used to classify the supernova type since non-Ia contamination can contribute a significant systematic error in the measurement of the cosmological parameters. A secondary effort is under way to use SNe Ia spectra at both high and low redshift as an independent tool to measure the intrinsic brightness of a supernova and to quantify/constrain possible evolutionary effects. PEN acknowledges ongoing support from the DOE and NASA.

Nugent, P.; Aldering, G.; Amanullah, R.; Antilogus, P.; Astier, P.; Balland, C.; Blanc, G.; Burns, M. S.; Conley, A.; Deustua, S.; Ellis, R.; Fabbro, S.; Folatelli, G.; Fruchter, A.; Garavini, G.; Gibbons, R.; Goldhaber, G.; Goobar, A.; Groom, D. E.; Hardin, D.; Hook, I. M.; Howell, D. A.; Irwin, M.; Kasen, D.; Kim, A.; Knop, R. A.; Levy, J.-M.; Lidman, C.; McMahon, R.; Mouchet, M.; Nobili, S.; Pain, R.; Panagia, N.; Pécontal, E.; Pennypacker, C. R.; Perlmutter, S.; Quimby, R.; Raux, J.; Regnault, N.; Ruiz-Lapuente, P.; Schaefer, B.; Schahmaneche, K.; Spadafora, A. L.; Walton, N.; Wang, L.; Wood-Vasey, W. M.; Supernova Cosmology Project Collaboration

2001-12-01

252

Energy Spectra in Relativistic Electron Precipitation Events.  

National Technical Information Service (NTIS)

Two events in August 1967, categorized as relativistic electron precipitation events by their effect on VHF transmissions propagated via the forward-scatter mode, were examined with regard to the energy spectra of trapped and precipitated electrons. In bo...

T. J. Rosenberg L. J. Lanzerotti D. K. Bailey J. D. Pierson

1972-01-01

253

Synthesis and Spectra of Vanadium Complexes.  

ERIC Educational Resources Information Center

|Describes an experiment which illustrates simple synthetic techniques, redox principles in synthesis reactions, interpretation of visible spectra using Orgel diagrams, and the spectrochemical series. The experiment is suitable for the advanced undergraduate inorganic chemistry laboratory. (JN)|

Ophardt, Charles E.; Stupgia, Sean

1984-01-01

254

Epaekoherentin Sironnan Spektri (Incoherent Radar Spectra).  

National Technical Information Service (NTIS)

General expressions for the incoherent scatter spectra are presented. These are relevant for the UHF radar in the monostatic backscatter case (thus excluding only the effect of the magnetic field), based on the Nyquist approach.

M. K. Vallinkoski

1987-01-01

255

TerumoBCT, Spectra Optia® Apheresis System  

Center for Biologics Evaluation and Research (CBER)

Text VersionPage 1. Spectra Optia® Apheresis System Mononuclear Cell (MNC) Collection Protocol New Plasma Transfer Feature Special 510(k) Submission ... More results from www.fda.gov/downloads/biologicsbloodvaccines/bloodbloodproducts

256

Molecular Dynamics and Spectra. II. Diatomic Raman.  

National Technical Information Service (NTIS)

This paper indicates that infrared and Raman rotational and fundamental vibrational-rotational spectra of dense systems (high pressure gases, liquids and solids) are essentially classical, in that they can be computed and understood from a basically class...

K. R. Wilson P. H. Berens S. R. White

1981-01-01

257

Theoretical Prediction of Vibrational Circular Dichroism Spectra.  

National Technical Information Service (NTIS)

A molecular species that is chiral possesses a Vibrational Circular Dichroism (VCD) spectrum. This study is the first step toward the development of a library of theoretically predicted VCD spectra. At this time we report the result of theoretical studies...

A. H. Carrieri C. F. Chabalowski D. Zeroka G. R. Famini

1990-01-01

258

PIA update: Correlation analyses of mass spectra  

NASA Astrophysics Data System (ADS)

The PIA instrument aboard the Giotto spacecraft (a time of flight spectrometer) has been presented elsewhere. The mass spectra used in this analysis were decoded and mass numbers assigned according to the presence of carbon and silver, using the global values for these elements in their spectral absence. The results presented here were obtained using a frequency of occurrence based on analysis which correlated how often mass numbers appear in the mass spectra and which mass numbers tend to occur together in the same spectra; no amplitude information is utilized. The data are presented as plots of mass vs coincident mass for different subsets of the PIA data set, with both axes having units of atomic mass. Frequency contours are plotted at approximately five percent contour intervals, relative to the maximum AMU occurrence in that plot. The plots presented are symmetrical about the matrix diagonal, i.e., every mass is coincident with itself in a given spectra.

Mason, L. W.; Clark, B. C.

1988-09-01

259

T1 weighted Brain Images at 7 Tesla Unbiased for Proton Density, T2* contrast and RF Coil Receive B1 Sensitivity with Simultaneous Vessel Visualization  

PubMed Central

At high magnetic field, MR images exhibit large, undesirable signal intensity variations commonly referred to as “intensity field bias”. Such inhomogeneities mostly originate from heterogeneous RF coil B1 profiles and, with no appropriate correction, are further pronounced when utilizing rooted sum of square reconstruction with receive coil arrays. These artifacts can significantly alter whole brain high resolution T1-weighted (T1w) images that are extensively utilized for clinical diagnosis, for gray/white matter segmentation as well as for coregistration with functional time series. In T1 weighted 3D-MPRAGE sequences, it is possible to preserve a bulk amount of T1 contrast through space by using adiabatic inversion RF pulses that are insensitive to transmit B1 variations above a minimum threshold. However, large intensity variations persist in the images, which are significantly more difficult to address at very high field where RF coil B1 profiles become more heterogeneous. Another characteristic of T1w MPRAGE sequences is their intrinsic sensitivity to Proton Density and T2* contrast, which cannot be removed with post-processing algorithms utilized to correct for receive coil sensitivity. In this paper, we demonstrate a simple technique capable of producing normalized, high resolution T1w 3D-MPRAGE images that are devoid of receive coil sensitivity, Proton Density and T2* contrast. These images, which are suitable for routinely obtaining whole brain tissue segmentation at 7 Tesla, provide higher T1 contrast specificity than standard MPRAGE acquisitions. Our results show that removing the Proton Density component can help identifying small brain structures and that T2* induced artifacts can be removed from the images. The resulting unbiased T1w images can also be used to generate Maximum Intensity Projection angiograms, without additional data acquisition, that are inherently registered with T1w structural images. In addition, we introduce a simple technique to reduce residual signal intensity variations induced by Transmit B1 heterogeneity. Because this approach requires two 3D images, one divided with the other, head motion could create serious problems, especially at high spatial resolution. To alleviate such inter-scan motion problems, we developed a new sequence where the two contrast acquisitions are interleaved within a single scan. This interleaved approach however comes with greater risk of intra-scan motion issues because of a longer single scan time. Users can choose between these two trade offs depending on specific protocols and patient populations. We believe that the simplicity and the robustness of this double contrast based approach to address intensity field bias at high field and improve T1 contrast specificity, together with the capability of simultaneously obtaining angiography maps, advantageously counter balance the potential drawbacks of the technique, mainly a longer acquisition time and a moderate reduction in signal to noise ratio.

Van de Moortele, Pierre-Francois; Auerbach, Edwards J.; Olman, Cheryl; Yacoub, Essa; Ugurbil, Kamil; Moeller, Steen

2009-01-01

260

THE SPITZER ATLAS OF STELLAR SPECTRA (SASS)  

SciTech Connect

We present the Spitzer Atlas of Stellar Spectra, which includes 159 stellar spectra (5-32 {mu}m; R {approx} 100) taken with the Infrared Spectrograph on the Spitzer Space Telescope. This Atlas gathers representative spectra of a broad section of the Hertzsprung-Russell diagram, intended to serve as a general stellar spectral reference in the mid-infrared. It includes stars from all luminosity classes, as well as Wolf-Rayet (WR) objects. Furthermore, it includes some objects of intrinsic interest, such as blue stragglers and certain pulsating variables. All of the spectra have been uniformly reduced, and all are available online. For dwarfs and giants, the spectra of early-type objects are relatively featureless, characterized by the presence of hydrogen lines in A spectral types. Besides these, the most noticeable photospheric features correspond to water vapor and silicon monoxide in late-type objects and methane and ammonia features at the latest spectral types. Most supergiant spectra in the Atlas present evidence of circumstellar gas and/or dust. The sample includes five M supergiant spectra, which show strong dust excesses and in some cases polycyclic aromatic hydrocarbon features. Sequences of WR stars present the well-known pattern of lines of He I and He II, as well as forbidden lines of ionized metals. The characteristic flat-top shape of the [Ne III] line is evident even at these low spectral resolutions. Several Luminous Blue Variables and other transition stars are present in the Atlas and show very diverse spectra, dominated by circumstellar gas and dust features. We show that the [8]-[24] Spitzer colors (IRAC and MIPS) are poor predictors of spectral type for most luminosity classes.

Ardila, David R. [NASA Herschel Science Center, California Institute of Technology, Mail Code 100-22, Pasadena, CA 91125 (United States); Van Dyk, Schuyler D.; Makowiecki, Wojciech; Stauffer, John; Rho, Jeonghee; Fajardo-Acosta, Sergio; Hoard, D. W.; Wachter, Stefanie [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Song, Inseok, E-mail: ardila@ipac.caltech.ed [Department of Physics and Astronomy, University of Georgia at Athens, GA 30602-2451 (United States)

2010-12-15

261

Optical spectra analysis for breast cancer diagnostics  

Microsoft Academic Search

Minimally invasive probe and optical biopsy system based on optical spectra recording and analysis seem to be a promising\\u000a tool for early diagnostics of breast cancer. Light scattering and absorption spectra are generated continuously as far as\\u000a the needle-like probe with one emitting and several collecting optical fibers penetrates through the tissues toward to the\\u000a suspicious area. That allows analyzing

S. A. Belkov; G. G. Kochemasov; T. E. Lyubynskaya; N. V. Maslov; A. S. Nuzhny; L. B. Da Silva; A. Rubenchik

262

Power and phase spectra for detonating cord  

SciTech Connect

A simple mathematical model is presented for a detonating cord seismic source. This model can be used for most configurations of detonating cord. Power and phase spectra are calculated. Numerical results are presented for a straight strand detonated in the center. Time delays associated with the initiation of vertically travelling energy at low frequencies can be determined from the phase spectra. 2 references, 5 figures.

Burkhard, N.R.

1983-11-01

263

Far Infrared Spectra of Magnetic Materials  

Microsoft Academic Search

The far infrared spectral region (?10?100 cm?1) corresponds to kT for T=15?150°K or ?H for H=105?106 oe. Materials with characteristic temperatures or fields of these orders of magnitude may have interesting far infrared spectra. We have studied far infrared resonance spectra in antiferromagnetic and in ferromagnetic rare-earth iron garnets.Antiferromagnets have a resonance frequency which depends on the exchange and anisotropy

M. Tinkham

1962-01-01

264

Interpretation of vibration spectra of metallochlorins  

SciTech Connect

The infrared spectra of Zn-chlorin and Zn-7,8-diethylchlorin, the fine structure of their fluorescence, and the vibrational spectra of Cu-chlorin are interpreted on the basis of normal-mode analysis. The effects of deuteration on the spectral shift of the chlorins is determined. Quantum-chemical calculations are presented which determine the electron density distribution and transitions between ground and vibrational states.

Gladkov, L.L.; Starukhin, A.S.; Shul'ga, A.M.

1987-08-01

265

Atomic Spectra Bibliography Databases at NIST  

Microsoft Academic Search

In June 2006, our Atomic Spectroscopy Data Center released three new Bibliographic Databases (BD) containing references to papers with atomic data for controlled fusion research, modeling and diagnostics of astrophysical and terrestrial plasmas, and fundamental properties of electronic spectra of atoms and ions. The NIST Atomic Energy Levels and Spectra BD (http:\\/\\/physics.nist.gov\\/elevbib) [EL] is the first online version of the

A. E. Kramida

2007-01-01

266

Atomic Spectra Bibliography Databases at NIST  

Microsoft Academic Search

NIST's Atomic Spectroscopy Data Center maintains three online Bibliographic Databases (BD) containing references to papers with atomic data for controlled fusion research, modeling and diagnostics of astrophysical and terrestrial plasmas, and fundamental properties of electronic spectra of atoms and ions. The NIST Atomic Energy Levels and Spectra BD [http:\\/\\/physics.nist.gov\\/elevbib] now includes about 11500 references, mostly for years 1967--2007. The NIST

Alexander Kramida

2008-01-01

267

Signatures of rotation in oscillation spectra  

NASA Astrophysics Data System (ADS)

Rotation makes oscillation spectra of rapidly rotating stars much more complicated. Hence, new strategies need to be developed in order to interpret such spectra. In what follows, we describe how multi-colour photometric mode visibilities can be generalised to rapidly rotating stars, while fully taking into account centrifugal deformation and gravity darkening. We then go on to describe some first results as well as a strategy for constraining mode identification.

Reese, D. R.; Prat, V.; Barban, C.; van't Veer-Menneret, C.; MacGregor, K. B.

2012-12-01

268

Evaluation of kurtosis of JONSWAP spectra  

NASA Astrophysics Data System (ADS)

Typical random wind waves in the sea are characterized by broad-band spectra and quasi-Gaussian statistics. While the evolution of wave field spectra in the ocean is well studied, very little is known about how departure of wave statistics from Gaussian depends on characteristics of wave spectra. This information is needed for many applications but is very difficult to extract from observations outside laboratory. It is common to characterize the departure of wave statistics from Gaussianity by value of kurtosis, a fourth-order statistical moment. Non-zero values of kurtosis mean an increased or decreased probability of extreme waves (compared to that in a Gaussian sea), which is important for assessing the risk of freak waves and other applications. For quasi-Gaussian waves there are two contributions to kurtosis. The first one, C4(b), is due to bound harmonics, while the second one, "dynamic kurtosis" C4(d), is linked to nonlinear wave-wave interactions. Under standard weak turbulence assumptions Janssen (2003) derived expressions for both components of kurtosis in terms of energy spectra. However, since the evaluation of the resulting 6-dimensional integrals is technically challenging, it has not been implemented for any experimental wave spectra. Here we evaluate C4(d) and C4(b) for the JONSWAP spectra, a widely used family of parametrisations of the observed spectra. We choose the k-form of the JONSWAP spectrum with the peak at k = 1. The frequency spectra are considered in the range 0.5 < ? < 3. The magnitude of the spectra is specified by parameter ?, where ? is proportional to the square of the steepness. The range of ? corresponds to the range of steepness from 0.04 to 0.3. The JONSWAP parameter ? characterizing "peakedness" of the spectra. ? is taken from 1 to 10. Angular distributions of the (cos?)N type are considered for several values of N. Thus we find behaviour of both components of kurtosis in the three-dimensional parameter space (?,?,N) and their sensitivity to approximations of the spectral shape. This provides a good idea on the degree of departure of wave statistics from Gaussian for realistic wave fields.

Annenkov, Sergei; Shrira, Victor

2013-04-01

269

Necessary conditions for a maximum likelihood estimate to become asymptotically unbiased and attain the Cramer-Rao lower bound. Part I. General approach with an application to time-delay and Doppler shift estimation.  

PubMed

Analytic expressions for the first order bias and second order covariance of a general maximum likelihood estimate (MLE) are presented. These expressions are used to determine general analytic conditions on sample size, or signal-to-noise ratio (SNR), that are necessary for a MLE to become asymptotically unbiased and attain minimum variance as expressed by the Cramer-Rao lower bound (CRLB). The expressions are then evaluated for multivariate Gaussian data. The results can be used to determine asymptotic biases. variances, and conditions for estimator optimality in a wide range of inverse problems encountered in ocean acoustics and many other disciplines. The results are then applied to rigorously determine conditions on SNR necessary for the MLE to become unbiased and attain minimum variance in the classical active sonar and radar time-delay and Doppler-shift estimation problems. The time-delay MLE is the time lag at the peak value of a matched filter output. It is shown that the matched filter estimate attains the CRLB for the signal's position when the SNR is much larger than the kurtosis of the expected signal's energy spectrum. The Doppler-shift MLE exhibits dual behavior for narrow band analytic signals. In a companion paper, the general theory presented here is applied to the problem of estimating the range and depth of an acoustic source submerged in an ocean waveguide. PMID:11681372

Naftali, E; Makris, N C

2001-10-01

270

Infrared spectra of urine from cancerous bladders  

NASA Astrophysics Data System (ADS)

The infrared spectra of organic constituents of urine from cancerous bladders of some patients were recorded. The spectra of the organic part of the samples were classified into five types according to the bulk constituents. Samples with type A spectra consisted mainly of proteins with only trace amounts of lipids. Their spectra were characterized mainly by the absorption bands of proteins at the frequencies 3330, 3075, 2960, 2850, 1650, 1530, 1450, 1400 and 1320 cm-1, in addition to a weak band at 1720 cm-1 due to the absorption of lipids. Samples with type B spectra were characterized by high amounts of proteins and low amounts of lipids and phosphate compounds. The presence of phosphate compounds was indicated by the absorption bands at the frequencies 1100 and 1030 cm-1. Samples giving spectral type C were characterized by high urea contents as indicated by the presence of two strong bands at 1670 and 1630 cm-1. Samples with the spectral type D consisted of urea and phosphate compounds whereas the last spectral type E consisted mainly of calcium oxalates, uric acids and phosphate compounds. The presence of calcium oxalates was indicated by the presence of its diagnostic bands at the frequencies 1630 and 1330 cm-1, while the presence of uric acid was indicated by the bands at the frequencies 1360, 1130, 1020 and 880 cm-1. On the other hand, the spectra of the organic part of urine from some normal bladders exhibited the characteristic bands of urea only. Careful examination of the spectra of the inorganic part of urine revealed that some samples consisted mainly of hydroxyapatite. The absorption bands of hydroxyapatite appeared at the frequencies 568, 603, 985, 1037 and 1128 cm-1. The spectra of other samples showed that the bands of basic phosphates at the frequencies 568, 620, 727, 890, 1035 and 1140 cm-1. The spectra of the inorganic part of urine from a number of normal bladders displayed the bands of basic phosphates. The relationship between urine constituents and pathological types of bladder tumor tissue was discussed.

Moharram, M. A.; Higazi, A.; Moharram, A. A.

1996-06-01

271

Group independent component analysis of MR spectra.  

PubMed

This study investigates the potential of independent component analysis (ICA) to provide a data-driven approach for group level analysis of magnetic resonance (MR) spectra. ICA collectively analyzes data to identify maximally independent components, each of which captures covarying resonances, including those from different metabolic sources. A comparative evaluation of the ICA approach with the more established LCModel method in analyzing two different noise-free, artifact-free, simulated data sets of known compositions is presented. The results from such ideal simulations demonstrate the ability of data-driven ICA to decompose data and accurately extract components resembling modeled basis spectra from both data sets, whereas the LCModel results suffer when the underlying model deviates from assumptions, thus highlighting the sensitivity of model-based approaches to modeling inaccuracies. Analyses with simulated data show that independent component weights are good estimates of concentrations, even of metabolites with low intensity singlet peaks, such as scyllo-inositol. ICA is also applied to single voxel spectra from 193 subjects, without correcting for baseline variations, line-width broadening or noise. The results provide evidence that, despite the presence of confounding artifacts, ICA can be used to analyze in vivo spectra and extract resonances of interest. ICA is a promising technique for decomposing MR spectral data into components resembling metabolite resonances, and therefore has the potential to provide a data-driven alternative to the use of metabolite concentrations derived from curve-fitting individual spectra in making group comparisons. PMID:23785655

Kalyanam, Ravi; Boutte, David; Gasparovic, Chuck; Hutchison, Kent E; Calhoun, Vince D

2013-03-13

272

Artificial intelligence analysis of paraspinal power spectra.  

PubMed

OBJECTIVE: As an aid to discrimination of sufferers with back pain an artificial intelligence neural network was constructed to differentiate paraspinal power spectra. DESIGN: Clinical investigation using surface electromyography. METHOD: The surface electromyogram power spectra from 60 subjects, 33 non-back-pain sufferers and 27 chronic back pain sufferers were used to construct a back propagation neural network that was then tested. Subjects were placed on a test frame in 30 degrees of lumbar forward flexion. An isometric load of two-thirds maximum voluntary contraction was held constant for 30 s whilst surface electromyograms were recorded at the level of the L(4-5). Paraspinal power spectra were calculated and loaded into the input layer of a three-layer back propagation network. The neural network classified the spectra into normal or back pain type. RESULTS: The back propagation neural was shown to have satisfactory convergence with a specificity of 79% and a sensitivity of 80%. CONCLUSIONS: Artificial intelligence neural networks appear to be a useful method of differentiating paraspinal power spectra in back-pain sufferers. PMID:11415655

Oliver, C W; Atsma, W J

1996-10-01

273

Background noise spectra of global seismic stations  

SciTech Connect

Over an extended period of time station noise spectra were collected from various sources for use in estimating the detection and location performance of global networks of seismic stations. As the database of noise spectra enlarged and duplicate entries became available, an effort was mounted to more carefully select station noise spectra while discarding others. This report discusses the methodology and criteria by which the noise spectra were selected. It also identifies and illustrates the station noise spectra which survived the selection process and which currently contribute to the modeling efforts. The resulting catalog of noise statistics not only benefits those who model network performance but also those who wish to select stations on the basis of their noise level as may occur in designing networks or in selecting seismological data for analysis on the basis of station noise level. In view of the various ways by which station noise were estimated by the different contributors, it is advisable that future efforts which predict network performance have available station noise data and spectral estimation methods which are compatible with the statistics underlying seismic noise. This appropriately requires (1) averaging noise over seasonal and/or diurnal cycles, (2) averaging noise over time intervals comparable to those employed by actual detectors, and (3) using logarithmic measures of the noise.

Wada, M.M.; Claassen, J.P.

1996-08-01

274

EXPLORING THE MORPHOLOGY OF RAVE STELLAR SPECTRA  

SciTech Connect

The RAdial Velocity Experiment (RAVE) is a medium-resolution (R {approx} 7500) spectroscopic survey of the Milky Way that has already obtained over half a million stellar spectra. They present a randomly selected magnitude-limited sample, so it is important to use a reliable and automated classification scheme that identifies normal single stars and discovers different types of peculiar stars. To this end, we present a morphological classification of {approx}350, 000 RAVE survey stellar spectra using locally linear embedding, a dimensionality reduction method that enables representing the complex spectral morphology in a low-dimensional projected space while still preserving the properties of the local neighborhoods of spectra. We find that the majority of all spectra in the database ({approx} 90%-95%) belong to normal single stars, but there is also a significant population of several types of peculiars. Among them, the most populated groups are those of various types of spectroscopic binary and chromospherically active stars. Both of them include several thousands of spectra. Particularly the latter group offers significant further investigation opportunities since activity of stars is a known proxy of stellar ages. Applying the same classification procedure to the sample of normal single stars alone shows that the shape of the projected manifold in two-dimensional space correlates with stellar temperature, surface gravity, and metallicity.

Matijevic, G.; Zwitter, T. [Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana (Slovenia); Bienayme, O.; Siebert, A. [Observatoire de Strasbourg, Universite de Strasbourg, CNRS, 11 rue de l'universite, 67000 Strasbourg (France); Bland-Hawthorn, J. [Sydney Institute for Astronomy, University of Sydney, NSW 2006 (Australia); Boeche, C.; Grebel, E. K. [Astronomisches Rechen-Institut, Zentrum fuer Astronomie der Universitaet Heidelberg, Moenchhofstr. 12-14, 69120 Heidelberg (Germany); Freeman, K. C. [Research School of Astronomy and Astrophysics, Australia National University, Weston Creek, Canberra, ACT 2611 (Australia); Gibson, B. K. [Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 3TE (United Kingdom); Gilmore, G. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Helmi, A. [Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700 AV Groningen (Netherlands); Munari, U. [INAF Osservatorio Astronomico di Padova, 36012 Asiago (Italy); Navarro, J. [Department of Physics and Astronomy, University of Victoria, Victora, BC V8P 5C2 (Canada); Parker, Q. A.; Reid, W. [Department of Physics and Astronomy, Macquarie University, NSW 2109 (Australia); Seabroke, G. [Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking RH5 6NT (United Kingdom); Siviero, A. [Department of Astronomy, Padova University, Vicolo dell'Osservatorio 2, 35122 Padova (Italy); Steinmetz, M.; Williams, M. [Leibniz-Institut fuer Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam (Germany); Watson, F. G., E-mail: gal.matijevic@fmf.uni-lj.si [Australian Astronomical Observatory, P.O. Box 296, Epping, NSW 2121 (Australia); and others

2012-06-01

275

Exploring the Morphology of RAVE Stellar Spectra  

NASA Astrophysics Data System (ADS)

The RAdial Velocity Experiment (RAVE) is a medium-resolution (R ~ 7500) spectroscopic survey of the Milky Way that has already obtained over half a million stellar spectra. They present a randomly selected magnitude-limited sample, so it is important to use a reliable and automated classification scheme that identifies normal single stars and discovers different types of peculiar stars. To this end, we present a morphological classification of ~350, 000 RAVE survey stellar spectra using locally linear embedding, a dimensionality reduction method that enables representing the complex spectral morphology in a low-dimensional projected space while still preserving the properties of the local neighborhoods of spectra. We find that the majority of all spectra in the database (~ 90%-95%) belong to normal single stars, but there is also a significant population of several types of peculiars. Among them, the most populated groups are those of various types of spectroscopic binary and chromospherically active stars. Both of them include several thousands of spectra. Particularly the latter group offers significant further investigation opportunities since activity of stars is a known proxy of stellar ages. Applying the same classification procedure to the sample of normal single stars alone shows that the shape of the projected manifold in two-dimensional space correlates with stellar temperature, surface gravity, and metallicity.

Matijevi?, G.; Zwitter, T.; Bienaymé, O.; Bland-Hawthorn, J.; Boeche, C.; Freeman, K. C.; Gibson, B. K.; Gilmore, G.; Grebel, E. K.; Helmi, A.; Munari, U.; Navarro, J.; Parker, Q. A.; Reid, W.; Seabroke, G.; Siebert, A.; Siviero, A.; Steinmetz, M.; Watson, F. G.; Williams, M.; Wyse, R. F. G.

2012-06-01

276

Isospin observables from fragment energy spectra  

NASA Astrophysics Data System (ADS)

The energy spectra of light charged particles and intermediate mass fragments from 112Sn+112Sn and 124Sn+124Sn collisions at an incident energy of E/A=50 MeV have been measured with a large array of silicon strip detectors. We used charged-particle multiplicities detected in an array with nearly 4? coverage to select data from the central collision events. We study isospin observables analogous to ratios of neutron and proton spectra, including double ratios and yield ratios of triton/3He and of asymmetries constructed from fragments with Z=3-8. Using the energy spectra, we can construct these observables as functions of kinetic energy. Most of the fragment asymmetry observables have a large sensitivity to sequential decays.

Liu, T. X.; Lynch, W. G.; Showalter, R. H.; Tsang, M. B.; Liu, X. D.; Tan, W. P.; van Goethem, M. J.; Verde, G.; Wagner, A.; Xi, H. F.; Xu, H. S.; Famiano, M. A.; de Souza, R. T.; Viola, V. E.; Charity, R. J.; Sobotka, L. G.

2012-08-01

277

Rotational Spectra of Vibrationally Excited HCL  

NASA Astrophysics Data System (ADS)

Survey spectra of a cold, inductively coupled discharge through He and HCl revealed a series of vibrationally excited transitions. The temperature dependence of these states was similar to that observed for the HCl cation and suggests a link in the formation or destruction mechanisms. Unlike the cation, the vibrational excitation was unaffected by larger concentrations of HCl and both were relatively insensitive to the pressure of the Helium buffer gas. Predictions based on band parameters from rotational spectra up to v = 2 and infrared overtone studies allowed rapid collection of spectra from v = 0 through v = 8 for both chlorine isotopologues. The new data set has been combined with existing rotational and infrared data in an isotope-independent Dunham model and fitted. We will compare this refined model to previous isotope-independent models of HCl.

Drouin, Brian J.; Gupta, Harshal

2012-06-01

278

Electronic spectra of asym-triazinyl groups  

SciTech Connect

The induction, resonance, and Hammett constants of 3-, 5-, and 6-asym-triazinyl groups were calculated from the data of /sup 1/H, /sup 13/C, /sup 19/F NMR spectra of isomeric aminophenyl-, hydroxyphenyl-, phenyl, and fluorophenyl-asym-triazines. The /sup 1/H and /sup 19/F NMR spectra of the solutions in dry DMSO under argon (in a concentration of 0.5 mole/liter) were recorded on a Varian A spectrometer at frequencies of 60 and 56.4 MHz, respectively; a /sup 13/C- DMSO satellite and C/sub 6/F/sub 6/ were used as internal standards. The /sup 13/C NMR spectra were recorded in a pulse regime on a Bruker HX-90 spectrometer at the frequency of 22.63 MHz, using TMS as internal standard. DMSO-D/sub 6/ (5%) was added to stabilize the resonance conditions.

Shkurko, O.P.; Gogin, L.L.; Baram, S.G.; Mamaev, V.P.

1987-08-01

279

Consistency of the minimal supersymmetric GUT spectra  

SciTech Connect

We show that with proper accounting of convention-dependent phases the mass spectra evaluated by us in an earlier paper satisfy the trace, SU(5) reassembly and Goldstone counting consistency checks. Phase accounting shows that the transposition symmetry called Hermiticity will be manifest only if signs arising from the product of six phase factors are reinserted. This uncovers the errors in the claims of others (retracted in subsequent work) concerning the inconsistency of our results. The chiral multiplet spectra of the two calculations are equivalent. However our method also gives all gauge and gauge chiral spectra as well as a decomposition of all SO(10) minimal supersymmetric grand unified theory couplings, for both tensors and spinors, which are unavailable, even in principle, using the methods of the above papers.

Aulakh, Charanjit S. [Department of Physics, Panjab University, Chandigarh, India 160014 (India)

2005-09-01

280

Empirical correction of RHESSI spectra for photospheric albedo and its effect on inferred electron spectra  

Microsoft Academic Search

Photospheric Compton backscatter (albedo) makes a significant contribution to observed hard X-ray (HXR) spectral fluxes over the RHESSI energy range and should be allowed for in spatially integrated HXR spectral interpretation. The high HXR spectral resolution of RHESSI creates the chance for precise study of source electron spectra provided the observed spectra are well corrected for non-primary effects at the

R. Calum Alexander; John C. Brown

2002-01-01

281

Infrared and ultraviolet spectra of organomercury compounds Communication 1. Infrared spectra of benzylmercury halides  

Microsoft Academic Search

1.The IR spectra of 20 benzylmercury halides, as well as dibenzylmercury, were studied for the first time in the region of 400–1650 cm-1.2.Various frequency regions of the spectra were discussed, and certain characteristic frequencies were found in the regions 500–600 and 760–790 cm-1.

Yu. A. Pentin; I. P. Beletskaya; B. Praisnar; O. A. Reutov

1965-01-01

282

Intrinsic Narrow Absorption Lines in Keck HIRES Spectra of a Sample of Six Quasars  

NASA Astrophysics Data System (ADS)

In the course of a large survey of intervening Mg II absorbers in the spectra of quasars, the C IV emission lines of six of the target objects (three radio-loud and three radio-quiet) were observed serendipitously. In four of these six quasars, we detected ``associated'' narrow absorption lines with velocities within 5000 km s^-1 of the quasar emission-line redshift (three of these four quasars are radio quiet while the other is radio loud). As a result of the original target selection, the small sample of six quasars is unbiased toward finding associated absorption lines. In three of these four cases, the absorption-line optical-depth ratios deviate from the prediction based on atomic physics, suggesting that the background photon source(s) are only partially covered by the absorbing medium and, by extension, that the absorption lines are intrinsic to the quasar. We have used the method of Barlow & Sargent to determine the effective coverage fraction of background source(s) and we have extended it to constrain the coverage fraction of the continuum and broad emission-line sources separately. We have also applied this refined method to the narrow intrinsic absorption lines in three additional quasars for which the necessary data were available from the literature. We find that in two objects from our sample, the continuum source must be partially covered regardless of the covering factor of the emission-line source. We discuss these results in the context of the properties of absorption lines observed in different types of active galaxies and related outflow phenomena. We cannot distinguish between possible mechanisms for the origin of the partial coverage signature, although we do consider possible observational tests. Finally, we speculate on how the gas responsible for the narrow lines may be related to the accretion disk wind that may be responsible for the broad absorption lines observed in some quasars.

Ganguly, Rajib; Eracleous, Michael; Charlton, Jane C.; Churchill, Christopher W.

1999-06-01

283

Near-infrared spectra of cataclysmic variables  

NASA Astrophysics Data System (ADS)

We present results from the first systematic survey of the near-infrared (1-2.5 microns) spectra of cataclysmic variables. Emission lines of H I and He I are present in most objects. He II emission is observed in V Sge. Lines from high-ionization species may be present in TT Ari and SS Cyg. Absorption features typical of late-type stars are detected in some systems. Spectra of SS Cyg over several years show possible variability of the absorption line strengths. On some occasions the absorption lines in SS Cyg may be stronger than those expected from a K5 V star.

Ramseyer, Tod F.; Dinerstein, Harriet L.; Lester, D. F.; Provencal, J.

1993-09-01

284

Observations and interpretation of star spectra  

NASA Astrophysics Data System (ADS)

The papers presented in this volume focus on the structures of the atmospheres of stars of different spectral classes. Topics discussed include automatic identification of spectral lines from IUE spectra; technetium content in the atmospheres of red giants; molecular absorption in cold star atmospheres; and determination of chemical element contents in the atmosphere of Gamma Tau. Papers are also presented on an analysis of C II carbon lines in B-star spectra; relative content of zirconium isotopes in the V Cancri atmosphere; and calculation of a peculiar model of the Nu Sgr atmosphere.

Kiselev, Nikolai N.

285

What can we learn from inclusive spectra  

SciTech Connect

The present experimental status on single particle inclusive measurements is described. Then, the geometrical aspect of the collision is discussed from the data of total integrated cross sections of nuclear charge or mass. The dynamical aspect of the collision, especially that for the participating region is discussed in connection with proton spectra, composite fragment spectra, pion production, ratios of ..pi../sup -//..pi../sup +/, n/p and t//sup 3/He, and production of strange particles. The spectator physics is described from the data on projectile fragments. (GHT)

Nagamiya, S.

1981-05-01

286

Optical absorption spectra of ? in ? (YGG)  

Microsoft Academic Search

Optical absorption spectra of trivalent europium in the rare-earth garnet 0953-8984\\/9\\/7\\/025\\/img3 (YGG) have been recorded between 4600 and 0953-8984\\/9\\/7\\/025\\/img4 at 77 and at 293 K. A total of 117 crystal-field transitions has been detected in the spectra. The symmetry of the 0953-8984\\/9\\/7\\/025\\/img5 site is 0953-8984\\/9\\/7\\/025\\/img6, so a total removal of the crystal-field degeneracy of the 0953-8984\\/9\\/7\\/025\\/img7 configuration can be expected.

K. Binnemans; C. Görller-Walrand

1997-01-01

287

NMR spectra of androstane analogs of brassinosteroids  

NASA Astrophysics Data System (ADS)

We have used two-dimensional NMR spectroscopy to make a complete assignment of signals from the nuclei of hydrogen and carbon atoms in the spectra of brassinosteroids in the androstane series. We have confirmed the stereochemistry of the chiral centers and the structure of the molecules. We have studied the effect of the configuration of the 2,3-diol groups in the A ring of the steroids on the chemical shift of adjacent atoms in the 13C and 1H NMR spectra.

Baranovskii, A. V.; Litvinovskaya, R. P.; Aver'kova, M. A.; Khripach, N. B.; Khripach, V. A.

2007-09-01

288

Baryon Spectra in Deformed Oscillator Quark Model  

NASA Astrophysics Data System (ADS)

We study theoretically the baryon spectra in terms of a deformed oscillator quark (DOQ) model. This model is motivated by confinement of quarks and chiral symmetry breaking, which are the most important nonperturbative phenomena of QCD. The minimization of the DOQ Hamiltonian with respect to the deformation for each principal quantum number results in deformations for the intrinsic states of excited baryonic states. We find that the resulting baryon spectra agree very well with the existing experimental data including SU(3) baryons. The spatial deformation of the baryonic excited states carry useful information on the quark confinement and provide a clue to understand the confining mechanism.

Hosaka, A.; Toki, H.; Takayama, M.

289

Micro-Raman spectra of ugrandite garnet.  

PubMed

The natural garnets from chromite ores associated with pegmatoid pyroxenites of Sangalyk area (Uchaly ore district, southern Urals, Russia) were studied by means of micro-Raman spectroscopy. The compositions of these garnets were close to ugrandite, an isomorphous intermediate group of uvarovite-grossularite-andradite, X(3)Y(2)(SiO(4))(3), X = Ca(2+), Y = Al(3+), Fe(3+), Cr(3+), according to Raman spectra and X-ray microprobe analyses. An assignment of most of the observed bands in visible and near infrared Raman spectra is reported. PMID:19084471

Moroz, T; Ragozin, A; Salikhov, D; Belikova, G; Puchkov, V; Kagi, H

2008-10-31

290

Infrared extinction spectra of aerosols (Sterken+, 2012)  

NASA Astrophysics Data System (ADS)

Mid-infrared extinction spectra (500-6000cm-1) of a ser single-component aerosol particle ensembles representative of those found in a range of planetary and lunar atmospheres are presented. The aerosols were generated in the laboratory via condensation from the gas phase in a bath gas cooling cell, and the spectra recorded using a Fourier transform infrared spectrometer. This paper is the first in a series aimed towards building a spectral database for use in remote sensing of aerosols. The aerosol substances included here are methane, ethane, propane, butane, pentane, ethylene, acetylene, carbon dioxide, ammonia and sulfur dioxide. (2 data files).

Knox, K. J.; Lang, E. K.; Signorell, R.

2012-02-01

291

Analysis of coupled bunch instability spectra  

SciTech Connect

Beam spectra observed during the development of a coupled bunch instability contain information about the coupled bunch mode n, which describes the phase shift between adjacent bunch oscillations. This number indicates the possible frequency of the guilty impedance with accuracy up to an integer multiple of the bunch spacing frequency. However when there are many possible candidates with imprecisely known frequencies this can be insufficient. In this paper we discuss what additional information about the frequency of the source of instability can be obtained from the analysis of the unstable beam spectra envelope. This is applied to the measurements in the CERN SPS.

Shaposhnikova, E. [CERN, Geneva (Switzerland)

1999-12-03

292

Absorption spectra of photosensitized human fat tissue  

NASA Astrophysics Data System (ADS)

We study experimentally the optical characteristics of adipose tissue in vitro in its dye sensitization—by indocyanin green and brilliant green. We conducted experiments on a PerkinElmer Lambda 950 spectrophotometer in the spectral range of 250-900 nm. From an analysis of the measured absorption spectra, we determine the shifts in the maximum of the absorption band for the studied photosensitizers in adipose tissue in comparison to their spectra in solutions. These shifts are explained by the bonding of photosensitizer molecules with the protein matrix of adipose tissue. We find the relative monomer and dimer concentrations of dye molecules in solutions and stained samples.

Yanina, I. Yu.; Simonenko, G. V.; Kochubey, V. I.; Tuchin, V. V.

2010-08-01

293

Parallel Genetic Algorithm for Alpha Spectra Fitting  

NASA Astrophysics Data System (ADS)

We present a performance study of alpha-particle spectra fitting using parallel Genetic Algorithm (GA). The method uses a two-step approach. In the first step we run parallel GA to find an initial solution for the second step, in which we use Levenberg-Marquardt (LM) method for a precise final fit. GA is a high resources-demanding method, so we use a Beowulf cluster for parallel simulation. The relationship between simulation time (and parallel efficiency) and processors number is studied using several alpha spectra, with the aim of obtaining a method to estimate the optimal processors number that must be used in a simulation.

García-Orellana, Carlos J.; Rubio-Montero, Pilar; González-Velasco, Horacio

2005-01-01

294

Absorption Spectra of Anodic Tantalum Oxide Films  

Microsoft Academic Search

N order to obtain additional information on optical and electronic properties of inorganic solids the ultraviolet absorption spectra of thin, anodically formed films of Ta206 have been determined. Oxide films were anodically formed on tantalum foil and made suitable for absorption measurements by removal of the support­ ing metal using a recently reported technique. I Tantalum foil, 0.0005 in. thick,

Wendell M. Graven

1961-01-01

295

Theory of recursive nuclear band spectra  

SciTech Connect

We first give a brief review of our earlier empirical work on parameter-free difference equations for nuclear spectra and discuss some of the implications. Then we show that a simple quantum mechanical model is capable of explaining and improving our previously suggested recursion relations.

Buck, B.; Merchant, A. C. [Department of Physics, University of Oxford, Theoretical Physics, 1 Keble Road, Oxford OX1 3NP (United Kingdom); Perez, S. M. [Department of Physics, University of Cape Town, Private Bag, Rondebosch 7700 (South Africa); iThemba LABS, P.O. Box 722, Somerset West 7129 (South Africa)

2010-03-15

296

Coxeter transformations and spectra of operations  

SciTech Connect

Coxeter transformations associated with rigged trees are considered. The number -1 plays an exceptional role with respect to the spectra of such trees. Systems of generating elements and operations are found in the sets of all rigged trees containing and not containing -1 in the spectrum.

Kolmykov, V A [Voronezh State University, Voronezh (Russian Federation)

2002-04-30

297

Auger Electron Spectra of Disordered Metallic Alloys  

Microsoft Academic Search

We calculate the Auger spectra from disordered alloys with partially filled bands described by the degenerate Hubbard model using the selfconsistent T-matrix approximation combined with the coherent potential approximation. The theory is illustrated on a simple model for CuxNi1-x alloy. We analyze in detail the approximations used and discuss possible improvements of the theory

V. Drchal; J. Kudrnovský

1992-01-01

298

Discriminating Dysarthria Type from Envelope Modulation Spectra  

ERIC Educational Resources Information Center

|Purpose: Previous research demonstrated the ability of temporally based rhythm metrics to distinguish among dysarthrias with different prosodic deficit profiles (J. M. Liss et al., 2009). The authors examined whether comparable results could be obtained by an automated analysis of speech envelope modulation spectra (EMS), which quantifies the…

Liss, Julie M.; LeGendre, Sue; Lotto, Andrew J.

2010-01-01

299

Microdosimetric spectra measurements of JANUS neutrons  

SciTech Connect

Neutron radiation from the JANUS reactor at Argonne National Laboratory is being used with increasing frequency for major biological experiments. The fast neutron spectrum has a Kerma-weighted mean energy of 0.8 MeV and low gamma-ray contamination. In 1984 the JANUS fission converter plate of highly enriched uranium was replaced by one made of low-enriched uranium. We recorded microdosimetric spectra at several different positions in the high-flux irradiation room of JANUS before the change of the converter plate. Each set of measurements consisted of spectra taken at three different site diameters (0.5, 1.0, and 5.0 ..mu..m) and in both ''attenuator up'' and ''attenuator down'' configurations. At two conventional dosimetry reference positions, two sets of measurements were recorded. At three biological reference positions, measurements simulating several biological irradiation conditions, were taken. The dose rate at each position was estimated and compared with dose rates obtained previously by conventional dosimetry. Comparison of the different measurements showed no major change in spectra as a function of position or irradiation condition. First results from similar sets of measurements recorded after the installment of the new converter plate indicate no major change in the spectra. 11 refs., 4 figs., 5 tabs.

Marshall, I.R.; Williamson, F.S.

1985-01-01

300

Synthesis and absorption spectra of thienylphenylpropenol derivatives  

Microsoft Academic Search

Fourteen thienylphenylpropenol derivatives containing substituents of varying electronic nature were synthesized. IR and NMR spectroscopy established that the a, ß-unsaturated alcohols obtained belong to the trans series. The electronic and PMR spectra of the alcohols in neutral and acidic solutions were studied. A correlation was found between the chemical shifts of the proton of the alcohol hydroxyl group and the

V. F. Lavrushin; R. I. Pogonina; N. S. Pivnenko; V. P. Izvekov

1970-01-01

301

Ultraviolet Photoelectron Spectra of Gallium Arsenide Clusters.  

National Technical Information Service (NTIS)

The ultraviolet photoelectron spectra (UPS) of mass-selected negative gallium arsenide cluster ions in the 2-50 atom size range was measured with a photon energy of 7.9 eV. The measured photodetachment thresholds displayed a strong even/odd oscillation th...

C. Jin J. Conceicao K. J. Taylor R. E. Smalley

1990-01-01

302

Deterministic and probabilistic floor response spectra  

Microsoft Academic Search

The paper presents a comparative study for computing floor response spectra (FRS) for complex structures. For the purpose of validation and evaluation of the methods for practical application, a systematic comparison of two concepts, classical deterministic and probabilistic, was carried out as an example of a nuclear power plants structure. The deterministic method utilizes time history analyses compatible with the

Aleksandar Paskalov; Stefanie Reese

2003-01-01

303

Symmetry based study of positron annihilation spectra.  

National Technical Information Service (NTIS)

We describe a method for off-line analysis of spectra measured by two-dimensional angular correlation of annihilation radiation (2D-ACAR) positron spectroscopy. The method takes into account, at all its stages, two salient data features: the piecewise con...

G. Adam S. Adam

1995-01-01

304

Benford's law and complex atomic spectra  

Microsoft Academic Search

We found that in transition arrays of complex atomic spectra, the strengths of electric-dipolar lines obey Benford's law, which means that their significant digits follow a logarithmic distribution favoring the smallest values. This indicates that atomic processes result from the superposition of uncorrelated probability laws and that the occurrence of digits reflects the constraints induced by the selection rules. Furthermore,

Jean-Christophe Pain

2008-01-01

305

The Emission Spectra of Various Thermoluminescent Materials.  

National Technical Information Service (NTIS)

The thermoluminescence emission spectra of various materials were determined using a quartz-prism spectrograph. The materials studied include: CaF2:Mn, CaSO4:Mn, Li2B4O7:Mn, LiF(TLD-100), CaF2(MBLE), and a terbium-activated lithium-aluminosilicate thermol...

S. G. Gorbics

1966-01-01

306

Interpretation of Infrared Spectra, A Practical Approach  

NSDL National Science Digital Library

This 25-page PDF from John Coates discusses the basic rules of infrared spectral interpretation. The vibrational spectrum of a molecule is considered to be a unique physical property that can be used for identification purposes when compared to existing reference spectra. This is the basis for computer based spectral searching featured in this document.

Coates, John; Spectroscopynow.com

307

Calculated late time spectra of supernovae  

SciTech Connect

We consider here the nebular phase spectra of supernovae whose late time luminosity is provided by the radioactive decay of /sup 56/Ni and /sup 56/Co synthesized in the explosion. A broad variety of supernovae are known or suspected to fall in this category. This includes all SNIa and SNIb, and at least some SNII, in particular SN1987a. At sufficiently late times the expanding supernova becomes basically nebular in character due to its decreasing optical depth. The spectra produced during this stage contain information on the density and abundance structure of the entire supernova, as opposed to spectra near maximum light which are affected only by the outermost layers. A numerical model for nebular spectrum formation is therefore potentially very valuable for answering currently outstanding questions about the post-explosion supernova structure. As an example, we can hope to determine the degree of mixing which occurs between the layers of the ''onion-skin'' abundance structure predicted by current one dimensional explosion calculations. In the sections which follow, such a numerical model is briefly described and then applied to SN1972e, a typical SNIa, SN1985f, an SNIb, and finally to SN1987a. In the case of SN1987a predicted spectra are presented for the wavelength range from 1 to 100 microns at a time 300 days after explosion. 18 refs., 6 figs.

Axelrod, T.S.

1987-10-30

308

Mossbauer spectra analysis in amorphous system studies  

Microsoft Academic Search

In amorphous materials, the lack of long-range order as well as a relatively poor short-range order lead to a change in hyperfine interactions from nucleus to nucleus and the Mossbauer spectra have to be analysed in terms of a continuous distribution of characteristic parameters. A method is being proposed for calculation of simultaneous hyperfine magnetic fields and electric field gradient

P. Mangin; G. Marchal; M. Piecuch; C. Janot

1976-01-01

309

Wind Gradients and Variance of Doppler Spectra.  

National Technical Information Service (NTIS)

An X-band pulsed-Doppler radar having its beam fixed at an elevation angle of 3 deg, was used to measure radial velocity spectra in a light shower. Observations were made at intervals of 152 m between radar ranges of 7 and 18 km. It was found that the mea...

L. J. Battan J. B. Theiss

1971-01-01

310

Baryon Spectra in Deformed Oscillator Quark Model  

Microsoft Academic Search

We study theoretically the baryon spectra in terms of a deformed oscillator quark (DOQ) model. This model is motivated by confinement of quarks and chiral symmetry breaking, which are the most important nonperturbative phenomena of QCD. The minimization of the DOQ Hamiltonian with respect to the deformation for each principal quantum number results in deformations for the intrinsic states of

A. Hosaka; H. Toki; M. Takayama

1998-01-01

311

Infrared spectra of some nonreduced methanation catalysts  

Microsoft Academic Search

The infrared spectra (4000 to 400 cm⁻¹) of two commercial nonreduced methanation catalysts have been recorded and interpreted. The catalyst are prepared as mixtures of (a) nickel in a silica support and (b) nickel in an alumina support. Graphite is added to these mixtures as a binder to facilitate pressing of catalyst pellets for commercial use. It is revealed in

Eugene B. Bradley; John M. Stencel

1978-01-01

312

Determinations of photon spectra. Master's thesis  

SciTech Connect

A method is developed to unfold photon spectra from measurements obtained with a sodium iodide counting system. A response matrix is computed by combining photon cross sections with probability distributions of path lengths for incident and internally generated photons in the energy range 0-2.8 MeV. This matrix is inverted and multiplied by a measured pulse height spectrum to obtain the photon energy distribution incident upon the detector. This deconvolution procedure provides improved information about the energy continuum of incident photons and can enhanced the identification of discrete gamma energies. Experiments were performed to verify the unfolding methodology and to evaluate the feasibility and accuracy of this technique. Measured spectra were acquired from indoor and outdoor environments and unfolded. The results show that measured spectra overestimate the number of photons below 240 keV by up to 30 %. When the total exposure was calculated directly from the measured spectra, the low energy contribution was overestimated by a factor of two. This may have implications on the interpretation and calibration of energy dependent dosimeters used for occupational and environmental monitoring.

Wannigman, D.L.

1989-01-01

313

Dimensionality reduction for bio-medical spectra  

Microsoft Academic Search

The classification problem for high dimensional data (for example near infrared spectra of bio-fluids) is a challenging, cornerstone problem in bio-informatics. The problems in the field possess many measured, highly correlated variables, which typically come from digitization of continuous signals, and relatively few distinct samples, with the number of variables often far exceeding the number of observations. Fortunately, in practice,

Christopher Bowman; Richard Baumgartner; R. Somorjai

2002-01-01

314

Analysis of coupled bunch instability spectra  

Microsoft Academic Search

Beam spectra observed during the development of a coupled bunch instability contain information about the coupled bunch mode n, which describes the phase shift between adjacent bunch oscillations. This number indicates the possible frequency of the guilty impedance with accuracy up to an integer multiple of the bunch spacing frequency. However when there are many possible candidates with imprecisely known

Elena Shaposhnikova

1999-01-01

315

Processing and classification of protein mass spectra.  

PubMed

Among the many applications of mass spectrometry, biomarker pattern discovery from protein mass spectra has aroused considerable interest in the past few years. While research efforts have raised hopes of early and less invasive diagnosis, they have also brought to light the many issues to be tackled before mass-spectra-based proteomic patterns become routine clinical tools. Known issues cover the entire pipeline leading from sample collection through mass spectrometry analytics to biomarker pattern extraction, validation, and interpretation. This study focuses on the data-analytical phase, which takes as input mass spectra of biological specimens and discovers patterns of peak masses and intensities that discriminate between different pathological states. We survey current work and investigate computational issues concerning the different stages of the knowledge discovery process: exploratory analysis, quality control, and diverse transforms of mass spectra, followed by further dimensionality reduction, classification, and model evaluation. We conclude after a brief discussion of the critical biomedical task of analyzing discovered discriminatory patterns to identify their component proteins as well as interpret and validate their biological implications. PMID:16463283

Hilario, Melanie; Kalousis, Alexandros; Pellegrini, Christian; Müller, Markus

316

Pentaquark Spectra in the Diquark Picture  

Microsoft Academic Search

The masses of uuddbar d , uuddbar s and uussbar d pentaquarks are calculated in the framework of a semirelativistic effective QCD Hamiltonian, but with all auxiliary fields eliminated. The use of a diquark picture allows a correct treatment of the confinement, supposed here to be a Y-junction. With diquark masses fitted on the baryon spectra, ground state pentaquarks are

Claude Semay; Bernard Silvestre-Brac; Ilya M. Narodetskii

2004-01-01

317

Vibrational spectra of gaseous and liquid tetraethoxysilane.  

National Technical Information Service (NTIS)

Tetraethoxysilane (TEOS) is an interesting material for the Chemical Vapour Deposition (CVD) of thin silicon dioxide films. The infrared and Raman spectra of gaseous and liquid TEOS, Si(OC(sub 2)H(sub 5))(sub 4), have been recorded and a complete assignme...

M. G. M. Van der Vis R. J. M. Konings A. Oskam T. L. Snoeck

1992-01-01

318

Argon KLL and KLM Auger Electron Spectra  

Microsoft Academic Search

The complete KLL and KLM Auger electron spectra of argon have been recorded at high resolution. The satellite lines in the KLL spectrum have been investigated and relativistic multiconfigurational Dirac-Fock calculations have been made to suggest assignments for these structures. Investigations of the neon KLL spectrum are employed to interpret part of the shake-off satellites.

L. Asplund; P. Kelfve; B. Blomster; H. Siegbahn; K. Siegbahn

1977-01-01

319

Variations on supersymmetry breaking and neutrino spectra  

SciTech Connect

The problem of generating light neutrinos within supersymmetric models is discussed. It is shown that the hierarchy of scales induced by supersymmetry breaking can give rise to suppression factors of the correct order of magnitude to produce experimentally allowed neutrino spectra.

Borzumati, F.; Hamaguchi, K.; Nomura, Y.; Yanagida, T.

2000-12-11

320

X ray Spectra of OVV QSOS.  

National Technical Information Service (NTIS)

Results on X-ray observations of OVV QSOs with Ginga are reported. Nine objects with redshift ranging from 0.21 to 1.40 were observed. X-ray spectra in 2 to 20 keV were obtained from eight of them. Seven OVVs showed power law photon indices between 1.4 an...

T. Ohashi T. Kii F. Makino K. Hayashida H. Inoue

1989-01-01

321

Spectra and Gust Factors for Marine Winds  

Microsoft Academic Search

In the design of vessels, offshore structures and marine systems, both the peak wind loading and the fluctuation of the wind at certain frequencies must be considered. Spectra and gust factors are here derived from a unique set of wind turbulence measurements obtained at a stable platform 10 km off the coast of Nova Scotia.

Stuart D. Smith; P. Chandler

1987-01-01

322

Semiclassical analysis and pseudo-spectra  

Microsoft Academic Search

We prove an approximate spectral theorem for non-self-adjoint operators and investigate its applications to second-order differential operators in the semi-classical limit. This leads to the construction of a twisted FBI transform. We also investigate the connections between pseudo-spectra and boundary conditions in the semi-classical limit.

E. B. Davies

2005-01-01

323

Double integration of electron spin resonance spectra  

Microsoft Academic Search

A method is described for obtaining the double integration of electron spin resonance spectra, with the aid of a desk calculating machine. A typical spectrum can be doubly integrated in a few minutes, with an error not exceeding 5%. The method automatically corrects for base-line drift.

S J Wyard

1965-01-01

324

Longitudinal mode spectra of diode lasers  

SciTech Connect

A theory is presented which explains the longitudinal mode spectra of diode lasers. The theory is based on spontaneous emission coupling into the longitudinal modes and the excellent agreement with experimental data for both gain guided and real refractive index waveguide diode lasers is obtained because of the more accurate and detailed modeling of the spontaneous emission coupling and the laser itself.

Streifer, W.; Scifres, D.R.; Burnham, R.D.

1982-02-15

325

Discrimination of phytoplankton classes using characteristic spectra of 3D fluorescence spectra.  

PubMed

The discrimination of phytoplankton classes using the characteristic fluorescence spectra extracted from three-dimensional fluorescence spectra was investigated. Single species cultures of 11 phytoplankton species, representing 5 major phytoplankton divisions, were used. The 3D fluorescence spectra of the cultures grown at different temperatures (20 and 15 degrees C) and illumination intensities (140, 80 and 30 microM m(-2) s(-1)) were measured and their feature extraction methods were explored. Ordering Rayleigh and Raman scattering data as zero, the obtained excitation-emission matrices were processed by both singular value decomposition (SVD) and trilinear decomposition methods. The resulting first principal component can be regarded as the characteristic spectrum of the original 3D fluorescence spectrum. The analysis shows that such characteristic spectra have a discriminatory capability. At different temperatures, the characteristic spectra of Isochrysis galbana, Platymonas helgolanidica and Skeletonema costatuma have high degrees of similarity to their own species samples, while the spectra similarities of Alexandrium tamarense, Prorocentrum dentatum, Pseudo-nitzschia pungens, Chaetoceros curvisetus, Ch. Debilis, Ch. Didymus and Synechococcus sp. are not as significant as the other three species. C. curvisetus, Ch. Debilis and Ch. Didymus, belonging to genus Chaetoceros, have identical spectra and cannot be discriminated at all. Regarding all six diatom species as one class, the average discriminant error rate is below 9%. It is worth mentioning that the diatom class can be distinguished from A. tamarense and P. dentatum, which belong to Dinophyta. PMID:16024277

Zhang, Qian-Qian; Lei, Shu-He; Wang, Xiu-Lin; Wang, Lei; Zhu, Chen-Jian

2005-07-18

326

Improved predictions of reactor antineutrino spectra  

NASA Astrophysics Data System (ADS)

Precise predictions of the antineutrino spectra emitted by nuclear reactors is a key ingredient in measurements of reactor neutrino oscillations as well as in recent applications to the surveillance of power plants in the context of nonproliferation of nuclear weapons. We report new calculations including the latest information from nuclear databases and a detailed error budget. The first part of this work is the so-called ab initio approach where the total antineutrino spectrum is built from the sum of all ? branches of all fission products predicted by an evolution code. Systematic effects and missing information in nuclear databases lead to final relative uncertainties in the 10-20% range. A prediction of the antineutrino spectrum associated with the fission of U238 is given based on this ab initio method. For the dominant isotopes we developed a more accurate approach combining information from nuclear databases and reference electron spectra associated with the fission of U235, Pu239, and Pu241, measured at Institut Laue-Langevin (ILL) in the 1980s. We show how the anchor point of the measured total ? spectra can be used to suppress the uncertainty in nuclear databases while taking advantage of all the information they contain. We provide new reference antineutrino spectra for U235, Pu239, and Pu241 isotopes in the 2-8 MeV range. While the shapes of the spectra and their uncertainties are comparable to those of the previous analysis of the ILL data, the normalization is shifted by about +3% on average. In the perspective of the reanalysis of past experiments and direct use of these results by upcoming oscillation experiments, we discuss the various sources of errors and their correlations as well as the corrections induced by off-equilibrium effects.

Mueller, Th. A.; Lhuillier, D.; Fallot, M.; Letourneau, A.; Cormon, S.; Fechner, M.; Giot, L.; Lasserre, T.; Martino, J.; Mention, G.; Porta, A.; Yermia, F.

2011-05-01

327

Microwave Spectra of Fluoroformyloxyl and Fluorosulfate Radicals  

NASA Astrophysics Data System (ADS)

Rotational spectra of fluoroformyloxyl (FCO_2) and fluorosulfate radicals (FSO_3) were studied in their ground states. The spectra measured involve fine structures due to a unpaired electron as well as hyperfine interaction features due to 19F nucleus that can give rise to an additional hyperfine doubling of levels. These radicals are of the atmospheric interest, for example the FCO_2 radical may be produced by stratospheric degradations of HCFCs and HFCs . Their atmospheric presence can be now supported by Eyjafjallajokull volcano massive eruptions of gasses and dust particles containing Fluor and Sulfur. Both the radicals were prepared by a pyrolysis of a suitable precursor directly in a sample cell. Besides the radical spectra, the majority of spectral lines in observed spectra belongs to other molecular species. Therefore the identification of the radical lines was simplified by using an external magnetic field affecting only the radical species by the molecular Zeeman effect. The radicals FCO_2 and FSO_3 were measured in the frequency regions 125 -242 GHz and 93 - 430 GHz, respectively. From obtained transition frequencies the set of rotational, centrifugal distortion, fine and hyperfine constants were calculated. The study of the fluorosulfate radical was performed in the Prague laboratory for the first time. L. Kolesniková, J. Varga, H. Beckers, M. Šimecková, Z. Zelinger, L. Nová St?íteská, P. Kania, H. Willner, and Š. Urban: Detailed study of fine and hyperfine structures in rotational spectra of the free fluoroformyloxyl radical FCO2, J. Chem. Phys. 128 (2008) 1-8. L. Kolesniková, J. Varga, L. Nová St?íteská, H. Beckers, H. Willner, F. Aubke, and Š. Urban: The Ground State Rotational Spectrum of the Fluorosulfate, J. Chem. Phys. 130 (2009) 18430.

Urban, S.; Varga, J.; Kolesniková, L.; Meltzerová, Z.; Uhlíková, T.; Koucký, J.; Kania, P.; Beckers, H.; Willner, H.

2010-06-01

328

Raman spectra of carotenoids in natural products  

NASA Astrophysics Data System (ADS)

Resonance Raman spectra of naturally occurring carotenoids have been obtained from nautilus, periwinkle ( Littorina littorea) and clam shells under 514.5 nm excitation and these spectra are compared with the resonance Raman spectra obtained in situ from tomatoes, carrots, red peppers and saffron. The tomatoes, carrots and red peppers gave rise to resonance Raman spectra exhibiting a ?1 band at ca. 1520 cm -1, in keeping with its assignment to carotenoids with ca. nine conjugated carbon?carbon double bonds in their main chains, whereas the resonance Raman spectrum of saffron showed a ?1 band at 1537 cm -1 which can be assigned to crocetin, having seven conjugated carbon?carbon double bonds. A correlation between ?1 wavenumber location and effective conjugated chain length has been used to interpret the data obtained from the shells, and the wavenumber position (1522 cm -1) of the ?1 band of the carotenoid in the orange clam shell suggests that it contains nine conjugated double bonds in the main chain. However, the black periwinkle and nautilus shells exhibit ?1 bands at 1504 and 1496 cm -1, respectively. On the basis of the correlation between ?1 wavenumber location and effective conjugated chain length, this indicates that they contain carotenoids with longer conjugated chains, the former having ca. 11 double bonds and the latter ca. 13 or even more. Raman spectra of the nautilus, periwinkle and clam shells also exhibited a strong band at 1085 cm -1 and a doublet with components at 701 and 705 cm -1, which can be assigned to biogenic calcium carbonate in the aragonite crystallographic form.

Withnall, Robert; Chowdhry, Babur Z.; Silver, Jack; Edwards, Howell G. M.; de Oliveira, Luiz F. C.

2003-08-01

329

Improved predictions of reactor antineutrino spectra  

SciTech Connect

Precise predictions of the antineutrino spectra emitted by nuclear reactors is a key ingredient in measurements of reactor neutrino oscillations as well as in recent applications to the surveillance of power plants in the context of nonproliferation of nuclear weapons. We report new calculations including the latest information from nuclear databases and a detailed error budget. The first part of this work is the so-called ab initio approach where the total antineutrino spectrum is built from the sum of all {beta} branches of all fission products predicted by an evolution code. Systematic effects and missing information in nuclear databases lead to final relative uncertainties in the 10-20% range. A prediction of the antineutrino spectrum associated with the fission of {sup 238}U is given based on this ab initio method. For the dominant isotopes we developed a more accurate approach combining information from nuclear databases and reference electron spectra associated with the fission of {sup 235}U, {sup 239}Pu, and {sup 241}Pu, measured at Institut Laue-Langevin (ILL) in the 1980s. We show how the anchor point of the measured total {beta} spectra can be used to suppress the uncertainty in nuclear databases while taking advantage of all the information they contain. We provide new reference antineutrino spectra for {sup 235}U, {sup 239}Pu, and {sup 241}Pu isotopes in the 2-8 MeV range. While the shapes of the spectra and their uncertainties are comparable to those of the previous analysis of the ILL data, the normalization is shifted by about +3% on average. In the perspective of the reanalysis of past experiments and direct use of these results by upcoming oscillation experiments, we discuss the various sources of errors and their correlations as well as the corrections induced by off-equilibrium effects.

Mueller, Th. A.; Lhuillier, D.; Letourneau, A. [Commissariat a l'Energie Atomique et aux Energies Alternatives, Centre de Saclay, IRFU/SPhN, FR-91191 Gif-sur-Yvette (France); Fallot, M.; Cormon, S.; Giot, L.; Martino, J.; Porta, A.; Yermia, F. [Laboratoire SUBATECH, Ecole des Mines de Nantes, Universite de Nantes, CNRS/IN2P3, 4 rue Alfred Kastler, FR-44307 Nantes Cedex 3 (France); Fechner, M.; Lasserre, T.; Mention, G. [Commissariat a l'Energie Atomique et aux Energies Alternatives, Centre de Saclay, IRFU/SPP, FR-91191 Gif-sur-Yvette (France)

2011-05-15

330

Analysis of Methods for Detecting the Proximity Effect in Quasar Spectra  

NASA Astrophysics Data System (ADS)

Using numerical simulations of structure formation, we investigate several methods for determining the strength of the proximity effect in the H I Ly? forest. We analyze three high-resolution (~10 kpc) redshift snapshots (\\overline{z}=4, 3, and 2.25) of a Hydro-Particle-Mesh simulation to obtain realistic absorption spectra of the H I Ly? forest. We model the proximity effect along the simulated sight lines with a simple analytical prescription based on the assumed quasar luminosity and the intensity of the cosmic UV background (UVB). We begin our analysis investigating the intrinsic biases thought to arise in the widely adopted standard technique of combining multiple lines of sight when searching for the proximity effect. We confirm the existence of these biases, albeit smaller than previously predicted with simple Monte Carlo simulations. We then concentrate on the analysis of the proximity effect along individual lines of sight. After determining its strength with a fiducial value of the UVB intensity, we construct the proximity effect strength distribution (PESD). We confirm that the PESD inferred from the simple averaging technique accurately recovers the input strength of the proximity effect at all redshifts. Moreover, the PESD closely follows the behaviors found in observed samples of quasar spectra. However, the PESD obtained from our new simulated sight lines presents some differences to that of simple Monte Carlo simulations. At all redshifts, we find a smaller dispersion of the strength parameters, the source of the corresponding smaller biases found when combining multiple lines of sight. After developing three new theoretical methods for recovering the strength of the proximity effect on individual lines of sight, we compare their accuracy to the PESD from the simple averaging technique. All our new approaches are based on the maximization of the likelihood function, albeit invoking some modifications. The new techniques presented here, in spite of their complexity, fail to recover the input proximity effect in an unbiased way, presumably due to some (unknown) higher order correlations in the spectrum. Thus, employing complex three-dimensional simulations, we provide strong evidence in favor of the PESD obtained from the simple averaging technique, as a method of estimating the UVB intensity, free of any intrinsic biases.

Dall'Aglio, Aldo; Gnedin, Nickolay Y.

2010-10-01

331

Designing density fluctuation spectra in inflation  

NASA Astrophysics Data System (ADS)

Scale-invariant (flat) fluctuation spectra are the most natural outcomes of inflation. Nonetheless current large-scale-structure observations seem to indicate more fluctuation power on large scales than flat spectra give. We consider a wide variety of models based on the chaotic inflation paradigm and sketch the effects that varying the expansion rate, structure of the potential surface, and the curvature coupling constants have on the quantum fluctuation spectra. We calculate in detail the quantum generation of fluctuation spectra by numerically solving the linearized perturbation equations for multiple scalar fields, the metric, and the radiation into which the scalars dissipate, following the evolution from inside the horizon through reheating. We conclude that (1) useful extended nonflat power laws are very difficult to realize in inflation, (2) double inflation leading to a mountain leveling off at a high-amplitude plateau at long wavelengths is generic, but to tune the cliff rising up to the plateau to lie in an interesting wavelength range, a special choice of initial conditions and/or scalar field potentials is required, and (3) small mountains (moguls) on the potential surface lead to mountains of extra power in the fluctuations added on top of an underlying flat spectrum. For quadratic and quartic couplings, the mountain fluctuations may obey Gaussian statistics but the spectral form will be very sensitive to initial conditions as well as potential parameters; non-Gaussian mountain fluctuations which depend upon potential parameters but not on initial field conditions will be the more likely outcome. However, adding cubic couplings can give mountains obeying Gaussian statistics independently of initial conditions. Since observations only probe a narrow patch of the potential surface, it is possible that it is littered with moguls, leading to arbitrarily complex ``mountain range'' spectra that can only be determined phenomenologically. We also construct an inflation model which houses the chaotic inflation picture within the grand unified theory (GUT) framework. The standard chaotic picture requires an unnaturally flat scalar field potential, ?~=5×10-14, and a strong curvature coupling parameter bound, ?<0.002. By allowing the Higgs field to be strongly coupled to gravity through a large negative curvature coupling strength, ?~-104, so the Planck mass depends on the GUT Higgs field, the Higgs field can be strongly coupled to matter fields [with ?~(?/105)2]. This leads to both a flat Zeldovich spectrum of the ``observed'' amplitude and a high reheating temperature (~1015 GeV), unlike the ?~10-13 standard case. The large -? would be related to the ratio of the Planck scale to a typical GUT scale. Although a single dynamically important Higgs multiplet gives flat spectra, a richer Higgs sector could lead to broken scale invariance.

Salopek, D. S.; Bond, J. R.; Bardeen, J. M.

1989-09-01

332

Observational and theoretical spectra of supernovae  

NASA Astrophysics Data System (ADS)

Progress in nuclear astrophysics by means of quantitative supernova spectroscopy is discussed with special concentration on type Ia, Ib and Ic and on SN 1987A. Spectral calculations continue to support an exploding C/O white dwarf as the best model of a SN Ia. Deflagration model W7 produces good maximum light spectra of SN Ia and seems to have a better composition distribution compared to delayed detonation models, but proper treatment of opacity remains a problem and the physical basis of SN Ia explosions is still not completely understood. All models for SN Ia predict large quantities of 56Co in the ejecta, but it is not clear that observations confirm this. Although the evolutionary origin of SN Ia remains uncertain, there is recent evidence that transfer of hydrogen in a binary system may be involved, as long suspected. There has been progress in comparing dynamical models with the optical/IR spectra of SN 1987A. The evolution of the [OI] ??6300, 6364 feature and the presence of strong persistent HeI ?10 830 indicate that both the envelope and core material contribute substantially to the formation of emission lines in the nebular phase and that neither the core nor the envelope can be neglected. Blending with nearby hydrogen lines may affect both of these spectral features, thereby complicating the analysis of the lines. The effects of continuum transfer and photoionization have been included and are under study. The discrepancies between theoretical and observed spectra are due primarily to the one-dimensional hydrodynamic models. The spectral data are not consistent with the high density ``spike'' (in radial coordinate) of the core material that is predicted by all such models. Analysis of the light curves of SN Ib and SN Ic supernovae implies that there are significant differences in their physical properties. Some SN Ib have considerably more ejecta mass than SN Ic events. SN Ib require He-rich atmospheres to produce the observed strong optical lines of HeI somewhat after maximum. SN Ic events require a considerable depletion, if not absence, of helium. Calculations of the nebular phase after about 200 days show that the optical spectra of SN Ib/c will not reveal HeI even if helium is present. The spectra at that phase are rather insensitive to variations in the mass and composition. The similarity of the optical spectra of SN Ib and Ic events at late times thus does not mean that they are physically very similar. Observations of the HeI ?10 830 line could provide a good diagnostic of the atmospheric composition of Sn Ib and SN Ic.

Wheeler, J. Craig; Swartz, Douglas A.; Harkness, Robert P.

1993-05-01

333

FUV spectra of planetary nebulae (Guerrero+, 2013)  

NASA Astrophysics Data System (ADS)

The occurrence of stellar wind in the central star of a planetary nebula (CSPN) can be revealed by the presence of P Cygni profiles of high-excitation lines overimposed on its stellar continuum. We have examined the entire Far-Ultraviolet Spectroscopic Explorer FUSE archive and merged all useful spectroscopic observations of CSPNe to produce the highest quality spectra that can be used to assess the occurrence of stellar winds. Furthermore, the individual spectra of each CSPN have been compared to search for variability in the P Cygni profile. P Cygni profiles of high-excitation lines have been found in 44 CSPNe, with a clear correlation between the ionization potential of the lines and the effective temperature of the star. (3 data files).

Guerrero, M. A.; de, Marco O.

2013-03-01

334

Optical absorption spectra of ? in ? (YGG)  

NASA Astrophysics Data System (ADS)

Optical absorption spectra of trivalent europium in the rare-earth garnet 0953-8984/9/7/025/img3 (YGG) have been recorded between 4600 and 0953-8984/9/7/025/img4 at 77 and at 293 K. A total of 117 crystal-field transitions has been detected in the spectra. The symmetry of the 0953-8984/9/7/025/img5 site is 0953-8984/9/7/025/img6, so a total removal of the crystal-field degeneracy of the 0953-8984/9/7/025/img7 configuration can be expected. The energy level scheme of 0953-8984/9/7/025/img5 in YGG is parametrized in terms of 20 free-ion parameters and nine crystal-field parameters. The crystal field is strong in the garnet host, so J-mixing has to be taken into account for the crystal-field calculation.

Binnemans, K.; Görller-Walrand, C.

1997-02-01

335

Peculiarities of atomic lines in sonoluminescense spectra  

NASA Astrophysics Data System (ADS)

Alkali-metal lines in SL spectra are broadened, asymmetrically shifted toward the red spectral region, unshifted narrow parent peaks are observed. The shape is influenced a number of parameters. The effects have no explanation. We model a line shape, assuming that line broadening arises from a density and line asymmetry results from superposition of spectra generated at different densities of a perturbing medium. Simulation shows that broad-band emission occurs within the density range of 10-400 Amg for KCl, LiCl, NaCl aqueous solutions under Ar at the ultrasound frequency of 20 kHz. The lower limit of the range shifts to higher density in order of K

Kazachek, M. V.; Gordeychuk, T. V.

2012-12-01

336

A library of galaxy spectra for Gaia  

NASA Astrophysics Data System (ADS)

The ESA satellite mission Gaia will acquire spectrophotometric observations of several million unresolved galaxies during its five years of operation. In order to implement a classification scheme for these observations we need to build a new library of galaxy spectra which covers the necessary parameter space. Using the evolutionary code PÉGASE.2 we have produced a library of 28885 synthetic galaxy spectra at zero redshift covering four general spectral types of galaxies over the wavelength range from 250 to 1050 nm, at a sampling of 1 nm or less. The library was also reproduced for four random values of redshift in the range of 0-0.2 and it is computed on a random grid of four key astrophysical parameters (3 for SFR and 1 for timescale of the infall of gas). The synthetic library was compared with various photometric and spectroscopic observations (e.g. from SDSS) and found in good agreement with them.

Tsalmantza, P.; Kontizas, M.; Rocca-Volmerange, B.; Bailer-Jones, C. A. L.; Kontizas, E.; Bellas-Velidis, I.; Korakitis, R.; Livanou, E.; Dapergolas, A.; Vallenari, A.; Fioc, M.

2009-05-01

337

Cathodoluminescence spectra of gallium nitride nanorods  

PubMed Central

Gallium nitride [GaN] nanorods grown on a Si(111) substrate at 720°C via plasma-assisted molecular beam epitaxy were studied by field-emission electron microscopy and cathodoluminescence [CL]. The surface topography and optical properties of the GaN nanorod cluster and single GaN nanorod were measured and discussed. The defect-related CL spectra of GaN nanorods and their dependence on temperature were investigated. The CL spectra along the length of the individual GaN nanorod were also studied. The results reveal that the 3.2-eV peak comes from the structural defect at the interface between the GaN nanorod and Si substrate. The surface state emission of the single GaN nanorod is stronger as the diameter of the GaN nanorod becomes smaller due to an increased surface-to-volume ratio.

2011-01-01

338

Neutron Spectra in a 15 MV LINAC  

SciTech Connect

Neutron spectra were calculated inside the treatment hall of a 15 MV LINAC, calculations were carried out using Monte Carlo methods. With a Bonner sphere spectrometer with pairs of thermoluminiscent dosimeters the neutron spectrum at 100 cm from the isocenter was measured and compared with the calculated spectrum. All the spectra in the treatment hall show the presence of evaporation and knock-on neutrons; also the room-return due to the hall features is shown. In the maze the large contribution are due to epithermal and thermal neutrons. A good agreement between the calculated and measured spectrum at 100 cm was noticed, from this comparison the differences are attributed to the water content in the concrete of the hall.

Vega-Carrillo, H. R. [Unidad Academica de Estudios Nucleares de la Universidad Autonoma de Zacatecas. Apdo. Postal 336, 98000 Zacatecas, Zac. (Mexico); Chu, Wei-Han [National Tsing Hua University, Hsinchu, Taiwan (China); Tung, Chuan-Jong [Chan Gung University, Taiwan (China); Lan, Jen-Hong [Chan Gung Memorial Hospital-Kaohsiung Medical Center and National Kaohsiung University, Kaohsiung, Taiwan (China)

2010-12-07

339

Bone densitometry using x-ray spectra  

NASA Astrophysics Data System (ADS)

In contrast to the two distinct energy regions that are involved in dual-energy x-ray absorptiometry for bone densitometry, the complete spectrum of a beam transmitted through two layers of different materials is utilized in this study to calculate the areal density of each material. Test objects constructed from aluminum and Plexiglas were used to simulate cortical bone and soft tissue, respectively. Solid-state HPGe (high-purity germanium) detectors provided high-resolution x-ray spectra over an energy range of approximately 20-80 keV. Areal densities were obtained from spectra using two methods: a system of equations for two spectral regions and a nonlinear fit of the entire spectrum. Good agreement with the known areal densities of aluminum was obtained over a wide range of PMMA thicknesses. The spectral method presented here can be used to decrease beam hardening at a small number of bodily points selected for examination.

Krmar, M.; Shukla, S.; Ganezer, K.

2010-10-01

340

Raman spectra of deuteriated taurine single crystals  

NASA Astrophysics Data System (ADS)

The polarized Raman spectra of partially deuteriated taurine [(ND 3+) 0.65(NH 3+) 0.35(CH 2) 2SO 3-] crystals from x( zz) x and x( zy) x scattering geometries of the A g and B g irreducible representations of the factor group C 2h are reported. The temperature-dependent Raman spectra of partially deuteriated taurine do not reveal any evidence of the structural phase transition undergone by normal taurine at about 250 K, but an anomaly observed in the 180 cm -1 band at ˜120 K implies a different dynamic for this band (which is involved in a pressure-induced phase transition) in the deuteriated crystal.

Souza, J. M. de; Lima, R. J. C.; Freire, P. T. C.; Sasaki, J. M.; Melo, F. E. A.; Filho, J. Mendes; Jones, Derry W.

2005-05-01

341

Primordial power spectra from anisotropic inflation  

SciTech Connect

We examine cosmological perturbations in a dynamical theory of inflation in which an Abelian gauge field couples directly to the inflaton, breaking conformal invariance. When the coupling between the gauge field and the inflaton takes a specific form, inflation becomes anisotropic and anisotropy can persist throughout inflation, avoiding Wald's no-hair theorem. After discussing scenarios in which anisotropy can persist during inflation, we calculate the dominant effects of a small persistent anisotropy on the primordial gravitational wave and curvature perturbation power spectra using the ''in-in'' formalism of perturbation theory. We find that the primordial power spectra of cosmological perturbations gain significant direction dependence and that the fractional direction dependence of the tensor power spectrum is suppressed in comparison to that of the scalar power spectrum.

Dulaney, Timothy R.; Gresham, Moira I. [California Institute of Technology, Pasadena, California 91125 (United States)

2010-05-15

342

Fourier deconvolution of photoacoustic FTIR spectra  

NASA Astrophysics Data System (ADS)

Fourier self-deconvolution is a fairly routine numerical method for increasing the apparent resolution of spectra in which the intrinsic bandwidths are much greater than the instrumental resolution. The present work demonstrates that a photoacoustic (PA) interferogram obtained with a Fourier transform spectrometer can be used directly in this calculation, without the usual intermediate computation of a spectrum. Phase errors in the interferogram must be eliminated as a first step in this procedure. The technique has been applied to PA IR interferograms acquired for an Alberta coal and for kaolinite, a common layer silicate. Several new bands were identified in the coal spectrum and assigned utilizing previously published results for coal. Results for kaolinite illustrate a behaviour characteristic of deconvolution of single bands; in addition, an OH-stretching band usually not detectable in IR spectra of kaolinite was observed and verified by comparison with Raman data.

Friesen, W. I.; Michaelian, K. H.

1986-07-01

343

Aladin, VO standards, Spectra and data cubes  

NASA Astrophysics Data System (ADS)

Aladin can be used as a VO portal for 3D spectroscopy DAL services. The new release is able to ingest data cubes and display them in movie mode. Lambda maps and spectra at one position can be excerpted. SIA services retrieving data cubes allow to describe in the metadata tree several access modes to the same dataset via DAL query response extensions. Interaction with tools like VOSPEC and SPLAT via PLASTIC protocol is emphasized.

Boch, T.; Fernique, P.; Bonnarel, F.

2008-10-01

344

GAMANAL. Interpretation of Gamma-Ray Spectra  

Microsoft Academic Search

GAMANAL provides a complete qualitative and quantitative analysis of mixtures of radioactive species such as fission products by computer interpretation of high-resolution gamma-ray spectra. The program first determines and removes the background or Compton continuum under the peaks in a spectrum to locate the peak regions. This is done by examining the pulse-height spectrum data for background and peak regions

Gunnink

1986-01-01

345

New USDA UVB synthetic spectra algorithm  

NASA Astrophysics Data System (ADS)

The US Department of Agriculture's (USDA), UVB Radiation Monitoring and Research Program1 makes routine measurements of ultraviolet radiation at over 30 sites in the United States, Canada and New Zealand. UV measurements of total, direct and diffuse horizontal irradiances, in seven spectral channels at two nm nominal bandwidths are made with a Yankee Scientific Inc., Multiple Filter Rotating Shadow band Radiometer (UV MFRSR). A similar instrument takes measurements in the visible region with 10 nm bandwidths. The UVB group has provided, upon request, a high resolution UV product referred to as "synthetic spectra," based on application of a non-linear estimation method described in Min and Harrison2 (1998) to UV MFRSR data. This presentation examines typical problems encountered when the synthetic spectra algorithm is applied to data collected at large solar zenith angles and when the application is extended to spectral regions beyond 368 nm, the center of the longest wavelength UV MFRSR channel. In particular, the effects on derived products such as the Caldwell or Flint3 action spectra are discussed. The useful spectral region of the algorithm has been expanded by including one or more of the datum from the visible MFRSR. This extension properly constrains the derived spectrum beyond 368 nm providing especially improved Flint action values, and can be used to estimate a PAR value if extended to include the 862 nm measurement. The extent of disagreement between measurements from LICOR PAR sensors and 'synthetic PAR' values will be presented. Planning for the next version of the synthetic spectra algorithm on the new USDA UVB web site is discussed.

Davis, John M.; Slusser, James R.

2005-08-01

346

Nuclear magnetic dipole moments from NMR spectra  

Microsoft Academic Search

In the procedure applied to extract the magnetic dipole moments of bare nuclei from NMR spectra of molecules the shielding of nuclei by electrons has been often described in a very crude manner. We determine the moments for 13C, 14N, 15N, 17O, 19F, 31P and 33S using more accurate shielding constants. Our gas phase NMR data are next used to

Andrej Antusek; Karol Jackowski; Micha? Jaszu?ski; Wlodzimierz Makulski; Marcin Wilczek

2005-01-01

347

Isotopic Spectra of the Hydroxyl Radical  

NASA Astrophysics Data System (ADS)

Rotational spectra of OH and its isotopologues have been precisely measured using high efficiency terahertz (THz) sources. The measurements are compared with existing data and are useful for global modeling. For the first time, microwave measurements of the --doubling transitions of the 17OH isotopologue are combined with THz data successfully. Precise rotational, fine-structure, and hyperfine structure parameters for the 17OH isotopologue are reported. An isotopically independent Dunham model for all isotopologues of 2- OH v < 3 is presented.

Drouin, Brian J.

2013-10-01

348

Optical spectra in Fibonacci photonic nanostructures  

Microsoft Academic Search

In this work, we have studied the transmission spectra of photonic band-gap Fibonacci quasiperiodic nanostructures composed of both positive (SiO2) and negative refractive index (n) materials, the so-called metamaterials. These left-handed materials has been receiving recently a lot of attention due to their novel properties, like the possibility of the construction of perfect lenses. Also, the mirror symmetry structure is

E. L. Albuquerque; F. F. de Medeiros; L. R. da Silva

2007-01-01

349

Mutation spectra of complex environmental mixtures  

Microsoft Academic Search

Bioassay-directed chemical analysis of complex environmental mixtures has indicated that much of the genotoxic activity of mixtures is due to the presence of one or a few classes or chemicals within the mixture. We have extended this observation to the molecular level by using colony probe hybridization and PCR\\/DNA sequence analysis to determine the mutation spectra of â¼8,000 revertants induced

DeMarini

1997-01-01

350

Radiospectroscopic and dielectric spectra of nanomaterials  

Microsoft Academic Search

The shape of lines in the radiospectroscopic (NMR and EPR) and dielectric spectra of materials formed by nanoparticles (hereafter,\\u000a nanomaterials) is analyzed theoretically. The theory is developed in the framework of the core and shell model according to\\u000a which a nanoparticle consists of two regions whose properties are affected and unaffected by the surface, respectively. The\\u000a changes in the resonance

M. D. Glinchuk; A. N. Morozovskaya

2003-01-01

351

Absorption spectra of photosensitized human fat tissue  

Microsoft Academic Search

We study experimentally the optical characteristics of adipose tissue in vitro in its dye sensitization—by indocyanin green\\u000a and brilliant green. We conducted experiments on a PerkinElmer Lambda 950 spectrophotometer in the spectral range of 250–900\\u000a nm. From an analysis of the measured absorption spectra, we determine the shifts in the maximum of the absorption band for\\u000a the studied photosensitizers in

I. Yu. Yanina; G. V. Simonenko; V. I. Kochubey; V. V. Tuchin

2010-01-01

352

Spectra of confined two-electron atoms  

NASA Astrophysics Data System (ADS)

Spectra of two electrons confined in a spherically symmetric potential of mixed Coulomb and harmonic form are studied using the Hartree-Fock and configuration interaction methods. The model studied corresponds to a two-electron atom confined in a harmonic oscillator potential. The spectral consequences of the interplay between the effects of the confinement due to the Hooke's law and due to the nuclear attraction force are investigated in detail.

Bielinska-Waz, D.; Karwowski, J.; Diercksen, G. H. F.

2001-05-01

353

Spectra of bigyrotropic magnetic photonic crystals  

NASA Astrophysics Data System (ADS)

We calculated the photonic band gap spectra of a one-dimensional magnetic photonic crystal made of alternating layers of bigyrotropic magnetic yttrium-iron garnet and nonmagnetic gadolinium gallium garnet. The forbidden regimes or band gaps in the electromagnetic wave spectrum were numerically obtained for the transversal magneto-optical configuration and compared with those for the polar and longitudinal magneto-optical configurations.

Lyubchanskii, I. L.; Dadoenkova, N. N.; Lyubchanskii, M. I.; Shapovalov, E. A.; Lakhtakia, A.; Rasing, Th.

2004-12-01

354

Automatic computer simulations of ESR spectra  

Microsoft Academic Search

A versatility of automatic ESR simulation procedures has been developed to obtain high quality of fitting and produce additional\\u000a information. The following examples are treated: derivation of long-range proton hyperfine coupling constants from unresolved\\u000a lines; determination of13C hf couplings from the naturally abundant isotope satellites; analyzing chemical exchange phenomena with two-sites model;\\u000a decomposition of superimposed spectra consisting of poorly resolved

A. Rockenbauer; L. Korecz

1996-01-01

355

Spectra of Ulysses {HISCALE} Electrons, 2001  

NASA Astrophysics Data System (ADS)

Fluxes of low-energy ( ~50 - 200 keV) electrons during Ulysses' solar south pole to north solar pole pass in 2001 were of sufficient magnitude to compute reliable power spectra in the frequency range where low-order and degree g- and p- solar oscillatory modes are expected. In the 100 to 1000 ?Hz frequency range the spectra are dominated by large peaks that are reproducible between different electron flux and energy channels. Moreover, almost all of these peaks correspond to predicted mode frequencies for 0 <= l <= 5 to within a few microhertz, although there appear to be some systematic differences between predictions and observations. Several of the large peaks in the spectra are sufficiently isolated in frequency to allow hypothesis tests for spherical harmonic dependence in heliographic latitude. (The spacecraft's motion means that space and time are confounded so that one cannot reliably detect modes by simply testing for periodic components. Instead, one must include the amplitude and phase changes expected for a given mode along the orbit.) Preliminary tests using narrow band filters on some tentatively identified modes show the expected amplitude and phase characteristics.

Thomson, D. J.; Maclennan, C. G.; Lanzerotti, L. J.

2002-12-01

356

Atomic Spectra Bibliography Databases at NIST  

NASA Astrophysics Data System (ADS)

In June 2006, our Atomic Spectroscopy Data Center released three new Bibliographic Databases (BD) containing references to papers with atomic data for controlled fusion research, modeling and diagnostics of astrophysical and terrestrial plasmas, and fundamental properties of electronic spectra of atoms and ions. The NIST Atomic Energy Levels and Spectra BD (http://physics.nist.gov/elevbib) [EL] is the first online version of the NIST bibliography on atomic energy levels and spectra, last published on paper in 1985. It includes more than 9300 references, mostly for years 1967 through 2004. Work is in progress to cover the latest years. The NIST Atomic Transition Probability BD, v. 8.1 (http://physics.nist.gov/fvalbib) [TP] with its 7200 references mainly covers years 1964 through 2006. The NIST Spectral Line Broadening BD, v. 2.0 (http://physics.nist.gov/linebrbib) [LB] has 3600 references, mostly for 1978 through 2006. It is a major upgrade of v. 1.0, which had only 800 references. All three databases are now maintained in a unified database management system that allows us to quickly update the contents. Updates become available to users on the next day. A new Data Entry module makes it easy to enter and categorize the data. This work is supported in part by the Office of Fusion Energy Sciences of the U.S. Department of Energy

Kramida, A. E.

2007-06-01

357

IRAS Low Resolution Spectra of Asteroids  

NASA Astrophysics Data System (ADS)

Optical/near-infrared studies of asteroids are based on reflected sunlight and surface albedo variations create broad spectral features, suggestive of families of materials. There is a significant literature on these features, but there is very little work in the thermal infrared that directly probes the materials emitting on the surfaces of asteroids. We have searched for and extracted 534 thermal spectra of 245 asteroids from the original Dutch (Groningen) archive of spectra observed by the IRAS Low Resolution Spectrometer (LRS). We find that, in general, the observed shapes of the spectral continua are inconsistent with that predicted by the standard thermal model used by IRAS. Thermal models such as proposed by Harris (1998) and Harris et al.(1998) for the near-earth asteroids with the "beaming parameter" in the range of 1.0 to 1.2 best represent the observed spectral shapes. This implies that the IRAS Minor Planet Survey (IMPS, Tedesco, 1992) and the Supplementary IMPS (SIMPS, Tedesco, et al., 2002) derived asteroid diameters are systematically underestimated, and the albedos are overestimated. We have tentatively identified several spectral features that appear to be diagnostic of at least families of materials. The variation of spectral features with taxonomic class hints that thermal infrared spectra can be a valuable tool for taxonomic classification of asteroids.

Cohen, Martin; Walker, Russell G.

2002-04-01

358

Variability in Optical Spectra of ? Orionis  

NASA Astrophysics Data System (ADS)

We present the results of a time-series analysis of 130 échelle spectra of ? Ori (B0 Ia), acquired over seven observing seasons between 1998 and 2006 at Ritter Observatory. The equivalent widths of H? (net) and He I ?5876 were measured and radial velocities were obtained from the central absorption of He I ?5876. Temporal variance spectra (TVS) revealed significant wind variability in both H? and He I ?5876. The He I TVS have a double-peaked profile consistent with radial velocity oscillations. A periodicity search was carried out on the equivalent width and radial velocity data, as well as on wavelength-binned spectra. This analysis has revealed several periods in the variability with time scales of 2-7 d. Many of these periods exhibit sinusoidal modulation in the associated phase diagrams. Several of these periods were present in both H? and He I, indicating a possible connection between the wind and the photosphere. Due to the harmonic nature of these periods, stellar pulsations may be the origin of some of the observed variability. Periods on the order of the rotational period were also detected in the He I line in the 98-99 season and in both lines during the 04-05 season. These periods may indicate rotational modulation due to structure in the wind.

Thompson, Gregory B.; Morrison, N. D.

2013-06-01

359

Quantization of Entropy Spectra of Black Holes  

NASA Astrophysics Data System (ADS)

From the quasinormal modes (QNM) of black holes, we obtain the quantizations of the entropy and horizon area of black holes via Bohr-Sommerfeld quantization, based on Bohr's correspondence principle. For this, we identify the appropriate action variable of the classical system corresponding to a black hole. By considering the BTZ black holes in topologically massive gravity as well as Einstein gravity, it is found that the spectra of not the horizon areas but the entropies of black holes are equally spaced. We also propose that other characteristic modes of black holes, which are non-QNM or holographic QNM, can be used in quantization of entropy spectra just like QNM. From these modes, it is found that only the entropy spectrum of the warped AdS3 black hole is equally spaced as well. Furthermore, by considering a scattering problem in a black hole, we propose that the total transmission modes and total reflection modes of black holes can be regarded as characteristic modes of black holes and result in the equally spaced entropy of the Kerr and Reissner-Nordström black holes. Finally, we conclude that there is a universal behavior that the entropy spectra of various black holes are equally spaced.

Kwon, Yongjoon; Nam, Soonkeon

2013-02-01

360

Variability in Optical Spectra of epsilon Orionis  

NASA Astrophysics Data System (ADS)

We present the results of a time series analysis of 130 échelle spectra of epsilon Ori (B0 Ia), acquired over seven observing seasons between 1998 and 2006 at Ritter Observatory. The equivalent widths of H? (net) and He I ?5876 were measured and radial velocities were obtained from the central absorption of He I ?5876. Temporal variance spectra (TVS) revealed significant wind variability in both H? and He I ?5876. The He I TVS have a double-peaked profile consistent with radial velocity oscillations. A periodicity search was carried out on the equivalent width and radial velocity data, as well as on wavelength-binned spectra. This analysis has revealed several periods in the variability with timescales of two to seven days. Many of these periods exhibit sinusoidal modulation in the associated phase diagrams. Several of these periods were present in both H? and He I, indicating a possible connection between the wind and the photosphere. Due to the harmonic nature of these periods, stellar pulsations may be the origin of some of the observed variability. Periods on the order of the rotational period were also detected in the He I line in the 1998-1999 season and in both lines during the 2004-2005 season. These periods may indicate rotational modulation due to structure in the wind.

Thompson, Gregory B.; Morrison, Nancy D.

2013-04-01

361

Secondary charged particle spectra and kerma calculations  

SciTech Connect

The calculation of kerma factors from known cross sections is not as simple as is often implied. The kerma factors are strongly influenced by the reaction mechanism assumed. An important example of this dependence on the reaction mechanism is the contribution of the /sup 12/C(n,n')3..cap alpha.. reaction to the total kerma in carbon. First, a short review will be given of the ENDF/B-V carbon cross sections which were used in the calculation of carbon kerma factors. Using the reaction channels implied in the ENDF/B-V evaluation, the contribution of various reactions to the total kerma factors in carbon will be given. A detailed analysis of the reaction mechanisms which could contribute to the (n,n')3..cap alpha.. reaction in carbon has been carried out. First their contribution to kerma, independent of cross section, will be calculated and then the initial spectra of alpha particles produced by the various reaction mechanisms will be given. A discussion of possible ways of experimentally distinguishing the reaction mechanisms will be made by comparing their different initial spectra and their variation in kerma with neutron energy. Finally, the event-size spectra for tissue-equivalent proportional counters will be presented, giving only the contributions from the (n,n')3..cap alpha.. reaction and its various possible reaction channels. 3 refs., 11 figs., 4 tabs.

Coyne, J.J.; Gerstenberg, H.M.; Hennen, L.A.

1985-09-16

362

Haloes Seen In UVIS Reflectance Spectra  

NASA Astrophysics Data System (ADS)

UVIS SOI reflectance spectra show bright ‘haloes’ around the locations of some of the strongest resonances in Saturn’s A ring (Esposito etal 2005). UV spectra constrain the size and composition of the icy ring particles (Bradley etal 2010, 2012). We investigate the Janus 4:3, 5:3, 6:5 and Mimas 5:3 inner Lindblad resonances as well as at the Mimas 5:3 vertical resonance (bending wave location). Models of ring particle regolith evolution (Elliott and Esposito 2010) indicate the deeper regolith is made of older and purer ice. The strong resonances cause streamline crowding (Lewis and Stewart 2005) which damps the interparticle velocity, allowing temporary clumps to grow, which in turn increase the velocity, eroding the clumps and releasing smaller particles and regolith (see the predator-prey model of Esposito etal 2012). This cyclic behavior, driven by the resonant perturbation from the moon, can yield collision velocities greater than 1m/sec, sufficient to erode the aggregates (Blum 2006), exposing older, purer materials. Thus, the radial location of the strongest resonances can be where we find both large aggregates and disrupted fragments, in a balance maintained by the periodic moon forcing. If this stirring exposes older, and purer ice, the velocity threshold for eroding the aggregates can explain why only the strongest Lindblad resonances show haloes. UVIS spectra can determine the relative contributions of particle size and purity at these locations, for comparison to estimates from the regolith evolution models.

Esposito, Larry W.; Bradley, E.; Colwell, J.; Sremcevic, M.

2012-10-01

363

Cygnus X-3 IR spectra (Fender+, 1999)  

NASA Astrophysics Data System (ADS)

We present four epochs, A, B, C and D, of resolution (?/??) = 1200, 2.12 micron spectroscopy of the peculiar X-ray binary Cygnus X-3. About a half dozen spectra taken with resolution 900, and at 1.62 micron are also included. These data were obtained using the FSpec near-infrared spectrometer (Williams, D., Thompson, C.L., Rieke, G.H., Montgomery, E. 1993, Proc. SPIE 1308, 482) on the Multiple Mirror Telescope (MMT). The MMT is located at an elevation of 2600 m at the top of Mt. Hopkins in southern Arizona and is jointly operated by the Smithsonian Astrophysics Observatory and the University of Arizona. The spectra are stored as ascii files, listing wavelength in Angstroms and relative flux. Each file contains a five line header, giving the UT, Heliocentric Julian date and phase of the X-ray system at the start of the integration, followed by the data points. Additional information about the spectra can be obtained in the paper. (1 data file).

Fender, R. P.; Hanson, M. M.; Pooley, G. G.

1999-05-01

364

DYNAMICAL ANALYSIS OF HIGHLY EXCITED MOLECULAR SPECTRA  

SciTech Connect

Spectra and internal dynamics of highly excited molecules are essential to understanding processes of fundamental importance for combustion, including intramolecular energy transfer and isomerization reactions. The goal of our program is to develop new theoretical tools to unravel information about intramolecular dynamics encoded in highly excited experimental spectra. We want to understand the formations of ''new vibrational modes'' when the ordinary normal modes picture breaks down in highly excited vibrations. We use bifurcation analysis of semiclassical versions of the effective Hamiltonians used by spectroscopists to fit complex experimental spectra. Specific molecular systems are of interest for their relevance to combustion and the availability of high-quality experimental data. Because of its immense importance in combustion, the isomerizing acetylene/vinylidene system has been the object of long-standing experimental and theoretical research. We have made significant progress in systematically understanding the bending dynamics of the acetylene system. We have begun to make progress on extending our methodology to the full bend-stretch vibrational degrees of freedom, including dynamics with multiple wells and above barrier motion, and time-dependent dynamics. For this, development of our previous methods using spectroscopic fitting Hamiltonians is needed, for example, for systems with multiple barriers.

Michael E. Kellman

2005-06-17

365

Soft X-ray properties of Seyfert galaxies. I. Spectra  

SciTech Connect

Results are presented from a study of soft X-ray spectra of 75 Seyfert galaxies observed by the Einstein Observatory IPC. The spectra in this sample (mostly high-luminosity Seyfert type 1s) are found to be consistent with a single power-law index alpha = 81. The AGN spectra observed with the IPC are compared with those from higher energy experiments, where AGN spectra have power law indices alpha = 0.7. It is found that the IPC spectra are systematically steeper than the HEAO 1 A-2 spectra of the same Seyfert galaxies, indicating a flattening toward higher energies. 110 refs.

Kruper, J.S.; Canizares, C.R.; Urry, C.M. (MIT, Cambridge, MA (USA) Space Telescope Science Institute, Baltimore, MD (USA))

1990-10-01

366

From plasmon spectra of metallic to vibron spectra of dielectric nanoparticles.  

PubMed

Light interacts surprisingly differently with small particles than with bulk or gas phase materials. This can cause rare phenomena such as the occurence of a "blue moon". Spectroscopic particle phenomena of similar physical origin have also spawned countless applications ranging from remote sensing to medicine. Despite the broad interest in particle spectra, their interpretation still poses many challenges. In this Account, we discuss the challenges associated with the analysis of infrared, or vibron, extinction spectra of small dielectric particles. The comparison with the more widely studied plasmon spectra of metallic nano-particles reveals many common features. The shape, size, and architecture of particles influence the band profiles in vibron and plasmon spectra in similar ways. However, the molecular structure of dielectric particles produces infrared spectral features that are more diverse and detailed or even unique to vibron spectra. More complexity means higher information content, but that also makes the spectra more difficult to interpret. Conventional models such as classical electromagnetic theory with a continuum description of the wavelength-dependent optical constants are often no longer applicable to these spectra. In cases where accurate optical constants are not available and for ultrafine particles, where the molecular structure and quantum effects become essential, researchers must resort to molecular models for light-particle interaction that do not require the prior knowledge of optical constants. In this Account, we illustrate how vibrational exciton approaches combined with molecular dynamics simulations and solid-state density functional calculations provide a viable solution to these challenges. Molecular models reveal two important characteristics of vibron spectra of small molecularly structured particles. The band profiles in vibron spectra are largely determined by transition dipole coupling between the molecules in a particle. Below a specific particle size limit, conventional models fail. Molecular models explain many other phenomena in particle spectra, such as size, shape, and mixing effects, providing the foundation for a better understanding of the interaction of solar radiation with aerosols and clouds and for the design of dielectric nanomaterials. PMID:22738352

Preston, Thomas C; Signorell, Ruth

2012-06-27

367

IUE-newsips spectra of sigma Geminorum  

NASA Astrophysics Data System (ADS)

The IUE spectra of sigma Gem have been taken from the NASA IUE archive using IDL (Interactive Data Language). The spectra have been observed in 1979-1986 period. All the spectra analysed in the present study have NEWSIPS reductions and consist of 25 LWP, 8 LWR and 5 SWP images in high resolution, and 2 LWP and 14 SWP images in low dispersion. The emission lines, identified as activity indicators and originating in the chromosphere and transition region, are seen in the spectra. The emission line fluxes and equivalent widths are computed based on Gaussian profile fitting procedures to examine the existence of any line flux variation that depends on time or orbital phase. It was found that there is a flux variation with time and orbital phase that is in good agreement with the photometric light curve variation. By comparing the flux variation with simultaneous light curve variation, it can be shown that there is a relation between the ultraviolet flux variation and the spot activity of the system, as shown by Ayres et al. (1984) and Engvold et al. (1988) based on their IUE (with IUESIPS reduction) spectral analysis. Moreover, it was inferred that there is no ultraviolet excess in sigma Gem by comparing the spectra of beta Gem taken as a comparison star. The Mg II h and k radial velocity curves of sigma Gem were in a good agreement with data obtained by Eker (1986) and Duemmler et al. (1997). The sinusoidal Mg II radial velocity curve solutions of the system give e = 0, P_orb. = 19.607+/-0.008 days, K = 34.86+/- 2.33 km s-1, gamma = 49.42+/- 1.87 km s-1 and T_o = 2445972.53+/- 0.28. Since the ultraviolet flux data are not conveniently distributed and are insufficient to determine the activity cycle, the evaluation of the ultraviolet flux activity cycle was not successful. Tables 3 to 11 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/391/641. Figures 1 to 10 are only available in electronic form at http://www.edpsciences.org

Ekmekçi, F.; Karaku?, O.

2002-08-01

368

Auger spectra of tetrahedral halides and hydrides  

SciTech Connect

Auger electron spectra are presented for the gas-phase molecular species CF/sub 4/, SiF/sub 4/, CCl/sub 4/, and SiCl/sub 4/ and discussed in terms of the effect of the interaction of the two final-state holes on the spectral line shapes. The highly polar character of the bonding for this series leads to systematic behavior with respect to this hole--hole interaction, showing rare gas-like localized halide spectra for SiF/sub 4/ and a delocalized component of increasing intensity as we proceed through the series to SiCl/sub 4/, CF/sub 4/, and CCl/sub 4/. The central atom spectra show a composite line shape resulting from the sum of two versions of the same one-electron final states but with different values of U (the hole--hole interaction energy). The Auger process occurs as a result of the electron density available at the central atom site but, since the one-electron orbitals are highly polarized towards the halide, the two holes principally appear around the halide sites. With both holes on the same halide site a rather large U results, but with the two holes on separate halide sites one obtains a reduced value of U. The relative intensity of the smaller U component appears to increase as we proceed through the series SiF/sub 4/, SiCl/sub 4/, CF/sub 4/, and CCl/sub 4/. This tendency in both the halide spectra and in the central atom spectra depends on the strength of the intersite interaction. The molecular parameter which seems most reasonable to predict this division between localized and delocalized behavior is the ratio of the halide--halide distance to the halide radius. In addition, we demonstrate that for a rather extended series of molecular species the trends in the value of U can be predicted surprisingly well on the basis of an experimental value of U for Ne and the known atomic and molecular dimensions. The implications of this simple predictive capability to other molecular systems is discussed.

Rye, R.R.; Houston, J.E.

1983-04-01

369

Infrared Extinction Spectra of Some Common Liquid Aerosols.  

National Technical Information Service (NTIS)

Infrared extinction spectra in the 3- to 5-micrometers and 7- to 13-micrometers atmospheric 'window' regions have been obtained for smokes of petroleum oil, sulphuric acid, and phosphoric acid of varying droplet concentration, and for water fogs. Spectra ...

H. R. Carlon D. H. Anderson M. E. Milham T. L. Tarnove R. H. Frickel

1976-01-01

370

Program LEPS to Addition of gamma Spectra from Germanium Detectors.  

National Technical Information Service (NTIS)

The ''LEPS'' program, written in FORTRAN IV, performs the addition of two spectra, collected with different detectors, from the same sample. This application, adds the two gamma spectra obtained from two opposite LEPS Germanium Detectors (Low Energy Photo...

L. Romero

1986-01-01

371

Study on Mössbauer spectra of hemoglobin in thalassemia  

NASA Astrophysics Data System (ADS)

The57Fe Mössbauer spectra of erythrocytes in normal subjects and nine patients of different thalassemias were studied. Together with clinical analysis, the correlation between the components in the spectra and different types of anemias was discussed.

Xuanhui, Guo; Nanming, Zhao; Xiufang, Zhang; Naifei, Gao; Youwen, Huang; Rongxin, Wang

1988-02-01

372

Elemental Composition and Energy Spectra of Galactic Cosmic Rays.  

National Technical Information Service (NTIS)

A brief review is presented of the major features of the elemental composition and energy spectra of galactic cosmic rays. The requirements for phenomenological models of cosmic ray composition and energy spectra are discussed, and possible improvements t...

R. A. Mewaldt

1988-01-01

373

Effect of Aluminum Substitution on the Emissivity Spectra of Hematite  

NASA Astrophysics Data System (ADS)

There are small differences in the emissivity spectra of the martian hematite found in Sinus Meridiani, Aram Chaos, and Valles Marineris. We report here on the effects of aluminum substitution on the emissivity spectra of hematite.

Glotch, T. D.; Morris, R. V.; Christensen, P. R.

2002-03-01

374

Effect of Aluminum Substitution on the Emissivity Spectra of Hematite  

Microsoft Academic Search

There are small differences in the emissivity spectra of the martian hematite found in Sinus Meridiani, Aram Chaos, and Valles Marineris. We report here on the effects of aluminum substitution on the emissivity spectra of hematite.

T. D. Glotch; R. V. Morris; P. R. Christensen

2002-01-01

375

Optimal construction of theoretical spectra for MS/MS spectra identification  

SciTech Connect

We derive the optimal number of peaks (defined as the minimum number that provides the required efficiency of spectra identification) in the theoretical spectra as a function of: (i) the experimental accuracy, , of the measured ratio m/z; (ii) experimental spectrum density; (iii) size of the database; (iv) number of peaks in the theoretical spectra; and (v) types of ions that the peaks represent. We show that if theoretical spectra are constructed including b and y ions alone, then for =0.5, which is typical for high throughput data, peptide chains of 8 amino acids or longer can be identified based on the positions of peaks alone, at a rate of false identification below 1%. To discriminate between shorter peptides, additional (e.g., intensity-inferred) information is necessary. We derive the dependence of the probability of false identification on the number of peaks in the theoretical spectra and on the types of ions that the peaks represent. Our results suggest that the class of mass spectrum identification problems for which more elaborate development of fragmentation rules (such as intensity model, etc.) is required, can be reduced to the problems that involve homologous peptides.

Fridman, Tamah [ORNL; Protopopescu, Vladimir A [ORNL; Hurst, Gregory {Greg} B [ORNL; Borziak, Andrei [ORNL; Gorin, Andrey A [ORNL

2005-01-01

376

Proposed reference irradiance spectra for solar energy systems testing  

Microsoft Academic Search

In 1982, the American Society for Testing and Materials (ASTM) adopted consensus standard solar terrestrial spectra (ASTM E891-82, E892-82) to provide standard spectra for photovoltaic (PV) performance applications. These spectra have been also used for other applications such as solar energy systems, fenestration, and materials degradation. These reference spectra were recomputed and the standards revised in 1987. The International Standards

C. A. Gueymard; D. Myers; K. Emery

2002-01-01

377

SNAP Spectrum Simulation: Spectra and Analysis  

NASA Astrophysics Data System (ADS)

We present results from the Supernova/Acceleration Probe (SNAP) spectrograph simulation framework. The SNAP spectrograph is an integral field slicer imager instrument with wavelength sensitivity of 0.9-1.7 ?m and resolution () of 100. The spectrometer will simultaneously procure the spectra of Type Ia Supernovae and host galaxies. High S/N spectra will be used to measure redshifts (up to z 3) and various explosion properties of Supernovae. In addition, the spectrograph will calibrate the spectro-photometric measurements crucial to weak gravitational lensing survey. We have integrated the standalone java-based spectrograph simulation, developed by A. Bonissent et al., with the SNAP simulation (SNAPSim) suite which is a parametric simulation tiered over a persistence-based framework. The integration required development and implementation of various interfaces along with several classes. The integrated suite is capable of realistically simulating the entire end-to-end mission with 2000+ supernovae with high S/N spectra that include all the significant effects due to the universe through the instrument (optics, filters, detectors and respective noises). In addition, the modular design of the simulation allows for simulating other missions for comparative analyses. The simulation suite extends as an effective test-bed for the engineering specifications and various mission-critical trade studies. We present results from the following studies, 1. Fisher Analysis of Supernova Type Ia diversity using spectral decomposition using Principal Component Analysis (PCA). 2. Spectral purity in the observed diverse population 3. S/N benchmark This is an on going effort.

Young, Edward; Shukla, H.; Bonissent, A.; Kim, A.; SNAP Collaboration

2007-12-01

378

Atomic and Molecular Aspects of Astronomical Spectra  

NASA Astrophysics Data System (ADS)

In the first section we present the atomic part where a C2+ atomic target was prepared and used to generate theoretical data to investigate recombination lines arising from electron-ion collisions in thin plasma. R-matrix method was used to describe the C2+ plus electron system. Theoretical data concerning bound and autoionizing states were generated in the intermediate-coupling approximation. The data were used to generate dielectronic recombination data for C+ which include transition lines, oscillator strengths, radiative transition probabilities, emissivities and dielectronic recombination coefficients. The data were cast in a line list containing 6187 optically-allowed transitions which include many C II lines observed in astronomical spectra. This line list was used to analyze the spectra from a number of astronomical objects, mainly planetary nebulae, and identify their electron temperature. The electron temperature investigation was also extended to include free electron energy analysis to investigate the long-standing problem of discrepancy between the results of recombination and forbidden lines analysis and its possible connection to the electron distribution. In the second section we present the results of our molecular investigation; the generation of a comprehensive, calculated line list of frequencies and transition probabilities for H2D+. The line list contains over 22 million rotational-vibrational transitions occurring between more than 33 thousand energy levels and covers frequencies up to 18500 cm-1. About 15% of these levels are fully assigned with approximate rotational and vibrational quantum numbers. A temperature-dependent partition function and cooling function are presented. Temperature-dependent synthetic spectra for the temperatures T=100, 500, 1000 and 2000 K in the frequency range 0-10000 cm-1 were also generated and presented graphically.

Sochi, Taha

2012-11-01

379

Low Temperature Reflectance Spectra of Titan Tholins  

NASA Astrophysics Data System (ADS)

Compositional interpretation of remotely obtained reflectance spectra of outer solar system surfaces is achieved by a variety of methods. These include matching spectral curves, matching spectral features, quantitative spectral interpretation, and theoretical modeling of spectra (e.g. Gaffey et al. Asteroids II, 1989). All of these approaches rely upon laboratory measurements of one kind or another. The bulk of these laboratory measurements are obtained with the sample of interest at ambient temperatures and pressures. However, surface temperatures of planets, satellites, and asteroids in the outer solar system are significantly cooler than ambient laboratory conditions on Earth. The infrared spectra of many materials change as a function of temperature. As has been recently demonstrated (Lucey et al., Icarus, in press, and references therein) it is important to assess what effects colder temperatures have on spectral properties and hence, compositional interpretations. Titan tholin is a solid residue created by energetic processing of H-, C-, and N-bearing gases (Khare et al. JGR, 1987). Such residues can also be created by energetic processing if the gases are condensed into ices (e.g. Khare et al. Icarus, 1993). Titan tholin has been suggested as a coloring agent for several surfaces in the outer solar system (Wilson et al. Icarus, 1994, Cruikshank et al. Icarus, 1998). Here we report laboratory measurements of Titan tholin at a temperature of 100 K and compare these to measurements of the same sample near room temperature. At low temperature the absorption features beyond 1 micrometer narrow slightly. At wavelengths greater than 0.8 micrometer the overall reflectance of the sample decreases slightly making the sample less red at low temperatures. We will discuss the implications of the laboratory measurements for interpretation of cold outer solar system surfaces. This research is supported by NASA's Planetary Geology and Geophysics Program.

Roush, T. L.; Dalton, J. B.

2001-11-01

380

Isotopic Spectra of the Hydroxyl Radical.  

PubMed

Rotational spectra of OH and its isotopologues have been precisely measured using high efficiency terahertz (THz) sources. The measurements are compared with existing data and are useful for global modeling. For the first time, microwave measurements of the ?-doubling transitions of the (17)OH isotopologue are combined with THz data successfully. Precise rotational, fine-structure, and hyperfine structure parameters for the (17)OH isotopologue are reported. An isotopically independent Dunham model for all isotopologues of (2)? OH v < 3 is presented. PMID:23634899

Drouin, Brian J

2013-05-20

381

High-energy spectra of atmospheric neutrinos  

NASA Astrophysics Data System (ADS)

A calculation of the atmospheric high-energy muon neutrino spectra and zenith-angle distributions is performed for two primary spectrum parameterizations (by Gaisser and Honda and by Zatsepin and Sokolskaya) with the use of QGSJET-II-03 and SIBYLL 2.1 hadronic models. A comparison of the zenith angle-averaged muon neutrino spectrum with the data of Frejus, AMANDA-II, and IceCube40 experiments makes it clear that, even at energies above 100 TeV, the prompt neutrino contribution is not apparent because of the considerable uncertainties of the experimental data in the high-energy region.

Petrova, O. N.; Sinegovskaya, T. S.; Sinegovsky, S. I.

2012-12-01

382

On The Spectra of Operator Completion Problems  

Microsoft Academic Search

\\u000a For an 2 × 2 operator matrix\\u000a $\\u000aM_X \\\\left( {{*{20}c}\\u000aA & C \\\\\\\\\\u000aX & B \\\\\\\\\\u000a } \\\\right)\\u000a$\\u000aM_X \\\\left( {\\\\begin{array}{*{20}c}\\u000aA & C \\\\\\\\\\u000aX & B \\\\\\\\\\u000a\\\\end{array} } \\\\right)\\u000a\\u000a on the Hilbert space H ? K, if A, B and C are given, we study the intersection and the union of the spectra

Hong-Ke Du; Caixing Gu

383

Spectra of electron oscillations in magnetoplasmadynamic thruster  

NASA Astrophysics Data System (ADS)

The intensity and spectra of electron oscillations in magnetoplasmadynamic (MPD) thruster have been experimentally studied. Oscillatory regimes corresponding to various relations between the relative gradients of magnetic field, electron concentration, and residual gas pressure in the vacuum chamber of the experimental setup have been determined. Relationship between the regimes of excitation of electron oscillations, the formation of an azimuthal current, and a change in the plasma flow potential is revealed. Model notions about the instability of plasma flow on low- and high-frequency branches of electron oscillations are developed.

Kirdyashev, K. P.; Kubarev, Yu. V.

2012-03-01

384

Magnetic Resonance Spectra and Statistical Geometry  

PubMed Central

Methods of statistical geometry are introduced which allow one to estimate, on the basis of computable criteria, the conditions under which maximally informative data may be collected. We note the important role of constraints which introduce curvature into parameter space and discuss the appropriate mathematical tools for treating curvature effects. Channel capacity, a term from communication theory, is suggested as a useful figure of merit for estimating the information content of spectra in the presence of noise. The tools introduced here are applied to the case of a model nitroxide system as a concrete example, but we stress that the methods described here are of general utility.

Mainali, Laxman; Sahu, Indra Dev; Schneider, David J.

2010-01-01

385

SPECTRA AND LIGHT CURVES OF FAILED SUPERNOVAE  

SciTech Connect

Astronomers have proposed a number of mechanisms to produce supernova explosions. Although many of these mechanisms are now not considered primary engines behind supernovae (SNe), they do produce transients that will be observed by upcoming ground-based surveys and NASA satellites. Here, we present the first radiation-hydrodynamics calculations of the spectra and light curves from three of these 'failed' SNe: SNe with considerable fallback, accretion-induced collapse of white dwarfs, and energetic helium flashes (also known as type Ia SNe).

Fryer, Chris L.; Dahl, Jon A.; Fontes, Christopher J., E-mail: fryer@lanl.go, E-mail: dahl@lanl.go, E-mail: cjf@lanl.go [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2009-12-10

386

Methane and the Spectra of T Dwarfs  

NASA Astrophysics Data System (ADS)

We have updated our PHOENIX model atmospheres and theoretical spectra for ultracool dwarfs with new opacity data for methane based on line strength predictions with the STDS software. By extending the line list to rotational levels of J = 40 we can significantly improve the shape of the near-IR absorption features of CH_4, and in addition find an enhanced blanketing effect, resulting in up to 50% more flux emerging in the J band than seen in previous models, which may thus contribute to the brightening in J and blue IR colors observed in T dwarfs.

Homeier, Derek; Hauschildt, Peter H.; Allard, France

2003-06-01

387

Electron ionization mass spectra of alkylated sulfabenzamides.  

PubMed

Mono-, di- and trialkyl derivatives of 'sulfabenzamide' (N-4-aminophenylsulfonylbenzamide) have been prepared and their electron ionization (EI) mass spectra examined. It is found that the fragmentation of N-alkylsulfabenzamides (alkyl?=?CH(3) to n-C(5)H(11)) proceeds via a very specific rearrangement process. The proposed mechanism involves an intermediate formation of distonic molecular ions, and the driving force for this process is the formation of stable N-alkylphenylcyanide cations [R-N(+)?CC(6)H(5)]. The findings are confirmed by exact mass measurements, tandem mass spectrometry (MS/MS) experiments and deuterium labeling. PMID:21337636

Todua, Nino G; Tretyakov, Kirill V; Borisov, Roman S; Zhilyaev, Dmitry I; Zaikin, Vladimir G; Stein, Stephen E; Mikaia, Anzor I

2011-03-30

388

Applying Zeeman Doppler imaging to solar spectra  

NASA Astrophysics Data System (ADS)

A new generation of spectro-polarimeters with high throughput (e.g. CFHT/ESPADONS and LBT/PEPSI) is becoming available. This opportunity can be exploited using Zeeman Doppler imaging (ZDI), a technique that inverts time-series of Stokes V spectra to map stellar surface magnetic fields (Semel 1989). ZDI is assisted by ``Least squares deconvolution'' (LSD), which sums up the signal from 1000's of photospheric lines to produce a mean deconvolved profile with higher S:N (Donati & Collier Cameron 1997).

Hussain, G. A. J.; Saar, S. H.; Collier Cameron, A.

2004-03-01

389

Exclusion Statistics in Conformal Field Theory Spectra  

NASA Astrophysics Data System (ADS)

We propose a new method for investigating the exclusion statistics of quasiparticles in conformal field theory (CFT) spectra. The method leads to one-particle distribution functions, which generalize the Fermi-Dirac distribution. For the simplest SU\\(n\\) invariant CFTs we find a generalization of Gentile parafermions, and we obtain new distributions for the simplest ZN-invariant CFTs. In special examples, our approach reproduces distributions based on ``fractional exclusion statistics'' in the sense of Haldane. We comment on applications to fractional quantum Hall effect edge theories.

Schoutens, Kareljan

1997-10-01

390

Phase correlated spectra of magnetic white dwarfs  

NASA Astrophysics Data System (ADS)

An improved model atmosphere technique is used for observations of the magnetic white dwarfs G 99-37 and G 99-47. New data were obtained during November 1987 using the ESO 1m-telescope for photometric measurements (73 observations), and the ESO 2.2m-telescope for polarimetry (42 observations). The Bamberg period analysis program calculated periods of 4.117h for G 99-37 and 0.97h for G 99-47. Spectra taken at various phases could be correlated and analyzed.

Bues, I.; Pragal, M.

391

Computing absolute and essential spectra using continuation  

NASA Astrophysics Data System (ADS)

A continuation approach to the computation of essential and absolute spectra of differential operators on the real line is presented. The advantages of this approach, compared with direct eigenvalue computations for the discretized operator, are the efficient and accurate computation of selected parts of the spectrum (typically those near the imaginary axis) and the option to compute nonlinear travelling waves and selected eigenvalues or other stability indicators simultaneously in order to locate accurately the onset to instability. We also discuss the implementation and usage of this approach with the software package AUTO and provide example computations for the FitzHugh Nagumo and the complex Ginzburg Landau equation.

Rademacher, Jens D. M.; Sandstede, Björn; Scheel, Arnd

2007-05-01

392

Calculated photoexcitation spectra of positronium Rydberg states  

NASA Astrophysics Data System (ADS)

Calculations of the photoexcitation spectra of ortho-positronium Rydberg states with principal quantum numbers between 10 and 30 are presented. The effects of Doppler broadening and saturation of the corresponding electric-dipole transitions are studied, together with the role of static and motionally induced electric fields. This is done in the context of recent measurements reported by Cassidy [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.108.043401 108, 043401 (2012)], and with regard to experiments involving the production of antihydrogen by charge-exchange between Rydberg positronium and cold antiprotons.

Hogan, S. D.

2013-06-01

393

Uncertainty Quantification on Prompt Fission Neutrons Spectra  

NASA Astrophysics Data System (ADS)

Uncertainties in the evaluated prompt fission neutrons spectra present in ENDF/B-VII.0 are assessed in the framework of the Los Alamos model. The methodology used to quantify the uncertainties on an evaluated spectrum is introduced. We also briefly review the Los Alamos model and single out the parameters that have the largest influence on the calculated results. Using a Kalman filter, experimental data and uncertainties are introduced to constrain model parameters, and construct an evaluated covariance matrix for the prompt neutrons spectrum. Preliminary results are shown in the case of neutron-induced fission of 235U from thermal up to 15 MeV incident energies.

Talou, P.; Madland, D. G.; Kawano, T.

2008-12-01

394

Average Lyman absorption from simulated QSO spectra  

NASA Astrophysics Data System (ADS)

Averagae flux decrements are computed below Ly-alpha and above Ly-beta, D(A) and between Ly-beta and the Lyman limit, D(B) of QSOs from synthetic spectra as a function of emission redshift on the basis of the presently known statistics of absorption lines. These simulations indicate that a steepening of the intrinsic spectrum of the QSO up to the Lyman limit is not required in order to explain the observed run of D(B)/D(A) with redshift, and that the average observed absorption is consistent with absorption line statistics.

Giallongo, E.; Gratton, R.; Trevese, D.

1990-06-01

395

Covariance analysis of gamma ray spectra.  

PubMed

The covariance method exploits fluctuations in signals to recover information encoded in correlations which are usually lost when signal averaging occurs. In nuclear spectroscopy it can be regarded as a generalization of the coincidence technique. The method can be used to extract signal from uncorrelated noise, to separate overlapping spectral peaks, to identify escape peaks, to reconstruct spectra from Compton continua, and to generate secondary spectral fingerprints. We discuss a few statistical considerations of the covariance method and present experimental examples of its use in gamma spectroscopy. PMID:23387645

Trainham, R; Tinsley, J

2013-01-01

396

Beta and Gamma Spectra of Short-Lived Fission Products  

Microsoft Academic Search

Continuous spectra of beta particles and gamma rays emitted in the decay of short-lived fission products have been measured. These spectra, which cover the complete energy range available, can be used for checking results of detailed spectroscopic work on the decay of the nuclides studied. Another application of basic nature is the use of the beta spectra to evaluate the

G. Rudstam; P. I. Johansson; O. Tengblad; P. Aagaard; J. Eriksen

1990-01-01

397

TRUCK LOAD SPECTRA INFLUENCED BY TRUCK WEIGHT LIMITS  

Microsoft Academic Search

Truck load represents a major load to highway facilities, such as bridges and pavements. Therefore truck load spectra are an important factor in the decision making process for these facilities, including design, evaluation, maintenance, and replacement. These load spectra are significantly influenced by the truck weight limits of the jurisdiction. This paper presents a method for predicting truck load spectra

Harry Cohen; Gongkang Fu; Waseem Dekelbab; Fred Moses

398

Corrected spectra of wind speed and significant wave height  

Microsoft Academic Search

In a recent paper (Monaldo, 1988) I presented spatial spectra of wind speed and significant wave height (SWH) variance. The spectra were calculated from spatial variations of wind speed and SWH as measured by the Seasat and Geosat radar altimeters. It has recently come to my attention that these spectra were incorrectly calculated. The shape of the corrected wind speed

Frank Monaldo

1990-01-01

399

Raman and fluorescence spectra of fluoro-organic compounds  

Microsoft Academic Search

The results of Raman and fluorescence spectra investigations of fluoroorganic aromatic compounds are presented. We present technique for realizing of qualitative and quantitative analysis of fluoroorganic aromatic compounds on the base of Raman and fluorescence spectroscopy. We propose to applicate the pulsed copper vapor laser for exciting of Raman and fluorescence spectra of fluoroorganic samples. The Raman spectra have been

Vladimir S. Gorelik; A. V. Chervyakov; L. I. Zlobina; Olga N. Sharts

1999-01-01

400

SPECTRAL DECONVOLUTION OF FLUORESCENCE SPECTRA FROM PLANT EXTRACTS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Fluorescence emission spectra have been observed to yield information pertaining to the identification of plant species. One approach to acquiring these characteristic spectra has been to record the spectral signature resulting from an extract of the plant. Often these spectra have been overwhelme...

401

Doppler spectra of the UHF diffuse radio aurora  

Microsoft Academic Search

A large number of radar backscatter Doppler spectra from the 398-MHz phased array at Homer, Alaska, have been analyzed for representative periods of widespread, long-lasting radar echoes in the premidnight and postmidnight sectors. Spectra corresponding to type 1 and type 2 echoes were observed. The type 1 spectra were most evident in the postmidnight data, where they appeared as velocity

G. E. Hall; D. R. Moorcroft

1988-01-01

402

Characterizing solar proton energy spectra for radiation effects applications  

Microsoft Academic Search

The Weibull distribution for smallest values is shown to be a useful description for solar proton event energy spectra. One advantage is its compact analytic expression, which allows easy conversion between differential and integral spectra. Another is its versatility, which is necessary for describing the highly variable spectra of concern. Furthermore, the Weibull distribution appears to be appropriate for use

M. A. Xapsos; J. L. Barth; E. G. Stassinopoulos; S. R. Messenger; R. J. Walters; G. P. Summers; E. A. Burke

2000-01-01

403

THE SPECTRA OF THE DOUBLY AND TRIPLY IONIZED RARE EARTHS  

Microsoft Academic Search

The present status of the knowledge of the structure of the spectra of ; the doubly and triply ionized spectra of the rare earths is derived partly from ; experimental data of the emission spectra of the free ions which provide the ; energy level scheme in great detail but are difficuit and laborious to analyze. ; For the lower

G. H. Dieke; H. M. Crosswhite

1963-01-01

404

Introductory Use of Infrared Spectra: A Formalized Approach.  

ERIC Educational Resources Information Center

Describes an approach which provides a basis for developing skills in interpreting infrared spectra and gives students a methodology which is functional without having to match "problem" spectra with "published" spectra. In addition, the suggested approach is reinforced easily by laboratory exercises involving known or unknown compounds. (JN)

McMinn, Dennis

1984-01-01

405

An Ultraviolet Atlas of Quasar and Blazar Spectra (Kinney+, 1991)  

Microsoft Academic Search

The spectra file currently present in this directory are the digital versions of the spectra that were extracted and co-added for the Ultraviolet Atlas of Quasar and Blazar Spectra, 1991 (reference above) The files contain the optimally extracted data which are described in \\

A. L. Kinney; R. C. Bohlin; J. C. Blades; D. G. York

1995-01-01

406

Infrared spectra of nitric and hydrochloric acid hydrate thin films  

Microsoft Academic Search

The mono-, di-, and trihydrates of nitric acid have been prepared as thin crystalline films and characterized by their distinctive infrared spectra. The infrared spectra of the mono- and trihydrates have been found to be significantly different than previously reported, to the extent that the published spectra are of questionable use. The spectrum of the dihydrate of HNOâ, which has

Gary Ritzhaupt; J. Paul Devlin

1991-01-01

407

FTIR Spectra of faceted diamonds and diamond simulants  

Microsoft Academic Search

FTIR spectra of faceted diamonds and diamond simulants collected by diffuse reflectance, transflectance, and specular reflection techniques were compared. The transflectance technique exploited total internal reflection phenomenon within the faceted diamond for the spectral acquisition. The transflectance spectra were similar to the well-accepted diffuse reflectance spectra with equal or better spectral qualities. Based on the observed spectral features of the

Pimthong Thongnopkun; Sanong Ekgasit

2005-01-01

408

Far-Infrared Spectra of Tertiary Ammonium Salts.  

National Technical Information Service (NTIS)

The far-infrared spectra of several tertiary ammonium salts have been studied in the solid state and in solution. The solution spectra do not reflect the symmetry of the ion aggregates that form in some solvents. The spectra are characterized by two broad...

G. Y. W. Kwong J. R. Kludt R. L. McDonald

1971-01-01

409

An improved algorithm for the retrieval of ocean wave spectra from synthetic aperture radar image spectra  

NASA Astrophysics Data System (ADS)

An earlier algorithm for retrieving two-dimensional wave spectra from synthetic aperture radar (SAR) image spectra is improved by using a modified cost function and introducing an additional iteration loop in which the first-guess input spectrum is systematically updated. For this purpose a spectral partitioning scheme is applied in which the spectrum is decomposed into a finite number of distinct wave systems. At each iteration step, the individual wave systems of the partitioned nth-guess wave spectrum are adjusted to agree in mean energy, frequency, and direction with the corresponding mean values of the associated wave systems of the SAR-inverted wave spectrum. The algorithm retrieves smooth wave spectra, avoiding the discontinuities which tended to arise in the previous algorithm in the transition region near the azimuthal wavenumber cutoff of the SAR image spectrum. The azimuthal cutoff of the SAR spectrum is also reproduced more accurately. The greatest improvement of the new retrieval algorithm is obtained when the discrepancies between the initial first-guess wave spectrum and the observed SAR spectrum are large. In this case the additional updating loop for the input spectrum enables the retrieved spectrum to adjust such that the simulated SAR spectrum matches more closely the observed SAR spectrum. The overall correlation of a large set of simulated SAR spectra with the measured SAR spectra is found to be significantly higher than with the previous algorithm, indicating that the algorithm not only overcomes isolated shortcomings of the earlier algorithm but also yields retrieved wave spectra which are generally more consistent with the input SAR data. An additional practical advantage of the new algorithm is that it returns spectral partioning parameters which can be used in SAR wave data assimilation schemes.

Hasselmann, S.; Brüning, C.; Hasselmann, K.; Heimbach, P.

1996-07-01

410

The perspectives of clinical staff and bereaved informal care-givers on the use of continuous sedation until death for cancer patients: The study protocol of the UNBIASED study  

PubMed Central

Background A significant minority of dying people experience refractory symptoms or extreme distress unresponsive to conventional therapies. In such circumstances, sedation may be used to decrease or remove consciousness until death occurs. This practice is described in a variety of ways, including: 'palliative sedation', 'terminal sedation', 'continuous deep sedation until death', 'proportionate sedation' or 'palliative sedation to unconsciousness'. Surveys show large unexplained variation in incidence of sedation at the end of life across countries and care settings and there are ethical concerns about the use, intentions, risks and significance of the practice in palliative care. There are also questions about how to explain international variation in the use of the practice. This protocol relates to the UNBIASED study (UK Netherlands Belgium International Sedation Study), which comprises three linked studies with separate funding sources in the UK, Belgium and the Netherlands. The aims of the study are to explore decision-making surrounding the application of continuous sedation until death in contemporary clinical practice, and to understand the experiences of clinical staff and decedents' informal care-givers of the use of continuous sedation until death and their perceptions of its contribution to the dying process. The UNBIASED study is part of the European Association for Palliative Care Research Network. Methods/Design To realize the study aims, a two-phase study has been designed. The study settings include: the domestic home, hospital and expert palliative care sites. Phase 1 consists of: a) focus groups with health care staff and bereaved informal care-givers; and b) a preliminary case notes review to study the range of sedation therapy provided at the end of life to cancer patients who died within a 12 week period. Phase 2 employs qualitative methods to develop 30 patient-centred case studies in each country. These involve interviews with staff and informal care-givers closely involved in the care of cancer patients who received continuous sedation until death. Discussion To our knowledge, this is one of the few studies which seek to take a qualitative perspective on clinical decision making surrounding the use of continuous sedation until death and the only one which includes the perspectives of nurses, physicians, as well as bereaved informal care-givers. It has several potential strengths, weaknesses, opportunities and threats associated with the specific design of the study, as well as with the sensitive nature of the topic and the different frameworks for ethical review in the participating countries.

2011-01-01

411

Computation of bremsstrahlung X-ray spectra and comparison with spectra measured with a Ge(Li) detector  

Microsoft Academic Search

A method of computing theoretical X-ray spectra in the range 30-150 kV is presented. The theoretical spectra are compared with constant potential, high resolution spectra from a tungsten target measured with a Ge(Li) detector, for a range of target angles, tube voltage and filtrations. Above 100 kV the spectra were also measured with a NaI detector but, as there was

R. Birch; M. Marshall

1979-01-01

412

Glueball spectra of SQCD-like theories  

NASA Astrophysics Data System (ADS)

We study the spectrum of scalar glueballs in SQCD-like theories whose gravity description is in terms of N c D5 color branes wrapped on an S 2 inside a CY3-fold, and N f backreacting D5 flavor branes wrapped on a non-compact two-cycle inside the same CY3-fold. We show that there exists a consistent truncation of the ten-dimensional Type IIB supergravity system to a five-dimensional non-linear sigma model consisting of four scalars coupled to gravity. Studying fluctuations of the scalars as well as the metric around particular backgrounds allows us to compute their spectra. A few different backgrounds share the same qualitative features, namely that the mass of the lightest scalar glueball increases as the number of flavors is increased, until one reaches the point N f = 2 N c after which the opposite behaviour is obtained. We show that the five-dimensional non-linear sigma model obeys Seiberg duality, and demonstrate this explicitly for the spectra of a class of backgrounds that are Seiberg dual to themselves.

Elander, Daniel

2010-03-01

413

Millimeter wave absorption spectra of biological samples  

SciTech Connect

A solid-state computer-controlled system has been used to make swept-frequency measurements of absorption of biological specimens from 26.5 to 90.0 GHz. A wide range of samples was used, including solutions of DNA and RNA, and suspensions of BHK-21/C13 cells, Candida albicans, C krusei, and Escherichia coli. Sharp spectra reported by other workers were not observed. The strong absorbance of water (10--30 dB/mm) caused the absorbance of all aqueous preparations that we examined to have a water-like dependence on frequency. Reduction of incident power (to below 1.0 microW), elimination of modulation, and control of temperature to assure cell viability were not found to significantly alter the water-dominated absorbance. Frozen samples of BHK-21/C13 cells tested at dry ice and liquid nitrogen temperatures were found to have average insertion loss reduced to 0.2 dB/cm but still showed no reproducible peaks that could be attributed to absorption spectra. It is concluded that the special resonances reported by others are likely to be in error.

Gandhi, O.P.; Hagmann, M.J.; Hill, D.W.; Partlow, L.M.; Bush, L.

1980-01-01

414

Protein Identification Using Top-Down Spectra*  

PubMed Central

In the last two years, because of advances in protein separation and mass spectrometry, top-down mass spectrometry moved from analyzing single proteins to analyzing complex samples and identifying hundreds and even thousands of proteins. However, computational tools for database search of top-down spectra against protein databases are still in their infancy. We describe MS-Align+, a fast algorithm for top-down protein identification based on spectral alignment that enables searches for unexpected post-translational modifications. We also propose a method for evaluating statistical significance of top-down protein identifications and further benchmark various software tools on two top-down data sets from Saccharomyces cerevisiae and Salmonella typhimurium. We demonstrate that MS-Align+ significantly increases the number of identified spectra as compared with MASCOT and OMSSA on both data sets. Although MS-Align+ and ProSightPC have similar performance on the Salmonella typhimurium data set, MS-Align+ outperforms ProSightPC on the (more complex) Saccharomyces cerevisiae data set.

Liu, Xiaowen; Sirotkin, Yakov; Shen, Yufeng; Anderson, Gordon; Tsai, Yihsuan S.; Ting, Ying S.; Goodlett, David R.; Smith, Richard D.; Bafna, Vineet; Pevzner, Pavel A.

2012-01-01

415

Determination of antineutrino spectra from nuclear reactors  

NASA Astrophysics Data System (ADS)

In this paper we study the effect of well-known higher-order corrections to the allowed ?-decay spectrum on the determination of antineutrino spectra resulting from the decays of fission fragments. In particular, we try to estimate the associated theory errors and find that induced currents like weak magnetism may ultimately limit our ability to improve the current accuracy and under certain circumstance could even greatly increase the theoretical errors. We also perform a critical evaluation of the errors associated with our method to extract the antineutrino spectrum using synthetic ? spectra. It turns out that a fit using only virtual ? branches with a judicious choice of the effective nuclear charge provides results with a minimal bias. We apply this method to actual data for 235U, 239Pu, and 241Pu and confirm, within errors, recent results, which indicate a net 3% upward shift in energy-averaged antineutrino fluxes. However, we also find significant shape differences which can, in principle, be tested by high-statistics antineutrino data samples.

Huber, Patrick

2011-08-01

416

Determination of antineutrino spectra from nuclear reactors  

SciTech Connect

In this paper we study the effect of well-known higher-order corrections to the allowed {beta}-decay spectrum on the determination of antineutrino spectra resulting from the decays of fission fragments. In particular, we try to estimate the associated theory errors and find that induced currents like weak magnetism may ultimately limit our ability to improve the current accuracy and under certain circumstance could even greatly increase the theoretical errors. We also perform a critical evaluation of the errors associated with our method to extract the antineutrino spectrum using synthetic {beta} spectra. It turns out that a fit using only virtual {beta} branches with a judicious choice of the effective nuclear charge provides results with a minimal bias. We apply this method to actual data for {sup 235}U, {sup 239}Pu, and {sup 241}Pu and confirm, within errors, recent results, which indicate a net 3% upward shift in energy-averaged antineutrino fluxes. However, we also find significant shape differences which can, in principle, be tested by high-statistics antineutrino data samples.

Huber, Patrick [Center for Neutrino Physics, Department of Physics, Virginia Tech, Blacksburg, Virginia 24061 (United States)

2011-08-15

417

INFRARED SPECTRA OF AMMONIA-WATER ICES  

SciTech Connect

We conducted a systematic study of the near-IR and mid-IR spectra of ammonia-water ices at various NH{sub 3}/H{sub 2}O ratios. The differences between the spectra of amorphous and crystalline ammonia-water ices were also investigated. The 2.0 {mu}m ammonia band central wavelength is a function of the ammonia/water ratio. It shifts from 2.006 {+-} 0.003 {mu}m (4985 {+-} 5 cm{sup -1}) to 1.993 {+-} 0.003 {mu}m (5018 {+-} 5 cm{sup -1}) as the percentage of ammonia decreases from 100% to 1%. The 2.2 {mu}m ammonia band center shifts from 2.229 {+-} 0.003 {mu}m (4486 {+-} 5 cm{sup -1}) to 2.208 {+-} 0.003 {mu}m (4528 {+-} 5 cm{sup -1}) over the same range. Temperature-dependent shifts of those bands are below the uncertainty of the measurement, and therefore are not detectable. These results are important for comparison with astronomical observations as well as for estimating the concentration of ammonia in outer solar system ices.

Zheng Weijun; Jewitt, David [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); Kaiser, Ralf I. [Department of Chemistry, University of Hawaii, Honolulu, HI 96822 (United States)], E-mail: jewitt@ifa.hawaii.edu, E-mail: ralfk@hawaii.edu, E-mail: zhengwj@iccas.ac.cn

2009-03-15

418

Intrinsic Spectra of Hyperluminous Infrared Galaxies  

NASA Astrophysics Data System (ADS)

We will use the low and high spectral resolution capabilities of the IRS aboard SIRTF to obtain high signal-to-noise mid-infrared spectra of a small sample of the most luminous Active Galactic Nuclei, which are characterized by their "warm" far-infrared spectral energy distributions as obtained by IRAS (the so called Hyperluminous Infrared Galaxies or HIGs). The sample consists of both Type 2 and Type 1 AGNs. The Type 1 objects present a relatively unobscured view of the central engine, and also have a polarized (scattered) component that is completely unobscured. The Type 2 objects have Type 1 polarized spectra, but this scattered light is highly extinguished indicating some obscuration even along the line of sight to the scattering region. The sample will allow us to compare the properties of the Type 1s and Type 2s, thus providing a check on the orientation and providing strong constraints on the geometry and internal structure of all four objects.

Rieke, George; Hines, Dean

2004-09-01

419

Stellar classification from simulated DIVA spectra  

NASA Astrophysics Data System (ADS)

The Double Interferometer for Visual Astrometry (DIVA) will obtain, apart from astrometry, intermediate-resolution spectra covering the entire visual range for over 10 million stars. The classification of such spectra according to T_eff and log g has been simulated. Using Kurucz spectral energy distributions and optional binning of the signal on the CCD detectors, simulated DIVA data have been produced in the spectral range of ~= 3130 to ~= 9990 Å. Binning of 4 or 8 pixels leads to 66 or 32 spectral bands. The band width (resulting from the point spread function of the DIVA optics) varies between ~= 160 and ~= 380 Å for 66 and between ~= 220 and ~= 400 Å for 32 bands. The Kurucz models (in ~= 20 Å steps) were scaled to V = 10, V = 12, or V = 14. The observational scatter was calculated for reasonable values for the DIVA CCD detector dark current and read-out noise. For hot stars of V ~= 12 the accuracy achieved for classification is ~= 0.5 in log g and ~= 10 percent in T_eff. For stars of intermediate temperature these accuracies are 0.3 in log g and 5 percent in temperature. For the coolest stars the accuracies are better than in the other temperature regimes. However, between 6000 and 4800 K the gravity determination turns out to be difficult. The results for 32 bands are, in general, as good as or better than those for 66 bands.

Elsner, B.; Scholz, R.; Bastian, U.; de Boer, K. S.; Liubertas, R.

420

Ten Micron Spectra of Nova Cygni 1992  

NASA Astrophysics Data System (ADS)

We present infrared spectra of Nova Cygni 1992 taken with SpectroCam-10, the Cornell-built 10 microns spectrograph/camera for the Hale 200-inch telescope, in April and August 1992. A low-resolution 8--13 microns spectrum on April 13.5 shows a strong [Ne {\\small II}] 12.8 microns emission line and several hydrogen recombination lines on top of the free-free continuum. High resolution (R = 2000) spectra of the [Ne {\\small II}] and Humphreys alpha 12.37 microns lines on the same date show them to be ~ 2000 km s(-1) FWHM. The [Ne {\\small II}] line has a double-peaked central core and broad wings. On August 9, all lines as well as the continuum were approximately 10% as bright as in April. The wings of the [Ne {\\small II}] lines had essentially disappeared, leaving the central core. From the relative intensity of the [Ne {\\small II}] line and the free continuum in April, we calculate that the abundance of neon relative to hydrogen is at least four times greater than the solar composition. There is no sign of emission from dust on either date.

Hayward, T. L.; Miles, J. W.; Houck, J. R.; Gehrz, R. D.

1992-12-01

421

Nonlinear Acoustic NDE Using Complete Nonclassical Spectra  

NASA Astrophysics Data System (ADS)

In the presence of cracked defects, material nonlinear response is determined by local contact dynamics which strongly depends on the amplitude of acoustic wave. At moderate driving amplitude, the contact acoustic nonlinearity suggests a fully deterministic scenario of higher harmonic generation and/or wave modulation. Unlike classical nonlinear materials, these effects feature much higher efficiency, specific dynamic characteristics, modulated spectra, and unconventional acoustic waveform distortion. At higher excitation, the contact vibrations acquire a dynamic instability which is a forerunner of transition to chaos. Such a dynamics is interpreted on the basis of nonlinear resonance phenomena for a defect conceived as a set of coupled oscillators. It is shown to result in a decay of external excitation into either a combination frequency pair or a subharmonic mode. For higher-order contact nonlinearity, the nonlinear spectrum expands considerably to include the ultra-subharmonic and ultra-frequency pair modes. Experiments show that even a moderate acoustic excitation of realistic cracked defects gives rise to the instability vibration modes which exhibit threshold behavior and distinctive hysteretic dynamics. All the modes-contributors to such non-classical nonlinear spectra display a high localization in the areas of nonlinear contacts and visualize readily various fractured defects in solids. The case studies presented include Hi-tech and constructional materials and demonstrate their applicability for defect-selective imaging in nonlinear NDE.

Solodov, I.; Pfleiderer, K.; Busse, G.

2006-05-01

422

Spontaneously quenched ?-ray spectra from compact sources  

NASA Astrophysics Data System (ADS)

Aims: We have studied a mechanism for producing intrinsic broken power-law ?-ray spectra in compact sources. This is based on the principles of automatic photon quenching, according to which ?-rays are being absorbed on spontaneously produced soft photons whenever the injected luminosity in ?-rays lies above a certain critical value. Methods: We derived an analytical expression for the critical ?-ray compactness in the case of power-law injection. For the case where automatic photon quenching is relevant, we calculated analytically the emergent steady-state ?-ray spectra. We also performed numerical calculations in order to back up our analytical results. Results: We show that a spontaneously quenched power-law ?-ray spectrum obtains a photon index 3?/2, where ? is the photon index of the power-law at injection. Thus, large spectral breaks of the ?-ray photon spectrum, e.g. ?? ? 1, can be obtained by this mechanism. We also discuss additional features of this mechanism that can be tested observationally. Finally, we fit the multiwavelength spectrum of a newly discovered blazar (PKS 0447-439) by using such parameters to explain the break in the ?-ray spectrum by means of spontaneous photon quenching, under the assumption that its redshift lies in the range 0.1 < z < 0.24.

Petropoulou, M.; Arfani, D.; Mastichiadis, A.

2013-09-01

423

Modelling Spectra and Lightcurves from Supernovae  

NASA Astrophysics Data System (ADS)

Explosive transient astronomy is entering an era where supernovae (SNe) and gamma-ray bursts will be observed in real time with surveys like the LSST and Pan-STARRS, probing the universe back to very early times. The discovery of Pop III SNe could reveal many details about the formation and evolution of the first stars. Observations of shock breakout in SNe will provide new information about the engines powering these explosions. Shock breakout occurs when the shock wave from core collapse reaches an optically thin region and radiation can stream out. This first burst of radiation interacts with the star's immediate surroundings, showing the effects of the surrounding environment on emission and evolution. This profusion of data will contain brief snapshots from a wide range of progenitor systems which simulations can help interpret and explain. We present a new pipeline for creating model supernova spectra and lightcurves using radiation-hydrodynamic simulations and a new Spectrum code. Spectrum maps 1-D or 2-D data onto a two dimensional grid and assumes rotational symmetry, using monochromatic opacities to calculate emission and absorption as a function of radius and angle. We use these spectra to create lightcurves in any band from infrared to x-ray. This pipeline is being used to study the effects of stellar environment on core-collapse and Type Ia SNe, as well as several types of Pop III SNe.

Frey, Lucille; Even, W.; Whalen, D.; Fryer, C.; Hungerford, A.; Fontes, C.

2012-01-01

424

Rotary spectra analysis applied to static stabilometry.  

PubMed

Static stabilometry is a technique aimed at quantifying postural sway during quiet standing in the upright position. Many different models and many different techniques to analyze the trajectories of the Centre of Pressure (CoP) have been proposed. Most of the parameters calculated according to these different approaches are affected by a relevant intra- and inter-subject variability or do not have a clear physiological interpretation. In this study we hypothesize that CoP trajectories have rotational characteristics, therefore we decompose them in clockwise and counter-clockwise components, using the rotary spectra analysis. Rotary spectra obtained studying a population of healthy subjects are described through the group average of spectral parameters, i.e., 95% spectral bandwidth, mean frequency, median frequency, and skewness. Results are reported for the clockwise and the counter-clockwise components and refer to the upright position maintained with eyes open or closed. This study demonstrates that the approach is feasible and that some of the spectral parameters are statistically different between the open and closed eyes conditions. More research is needed to demonstrate the clinical applicability of this approach, but results so far obtained are promising. PMID:22255446

Chiaramello, E; Knaflitz, M; Agostini, V

2011-01-01

425

Estimation of vertical sea level muon energy spectra from the latest primary cosmic ray elemental spectra  

NASA Astrophysics Data System (ADS)

The directly measured elemental spectra of primary cosmic rays obtained from Webber et al., Seo et al., Menn et al., Ryan et al. and experiments like JACEE, CRN, SOKOL, RICH on P, He, CNO, Ne-S and Fe have been considered to estimate the vertical sea level muon energy spectra. The primary elemental energy spectra of P, He, CNO, Ne-S and Fe available from the different experimental data duly fitted by power law are given by Np(E)dE = 1.2216E-2.68 dE [cm2 .s.sr.GeV/n]-1 NHe(E)dE = 0.0424E-2.59 dE [cm2 .s.sr.GeV/n]-1 NCNO(E)dE = 0.0026E-2.57 dE[cm2 .s.sr.GeV/n]-1 NNe-S(E)dE = 0.00066E-2.57 dE [cm2 .s.sr.GeV/n]-1 NF e(E)dE = 0.0056E-2.55 dE [cm2 .s.sr.GeV/n]-1 Using the conventional superposition model the all nucleon primary cosmic ray spectrum has been derived which is of the form N(E)dE = 1.42E-2.66 dE [cm2 .s.sr.GeV/n]-1 We have considered all these spectra separately as parents of the secondary mesons and finallty the sea level muon fluxes at 00 from each species have been derived. To evaluate the meson spectra which are the initial air shower interaction products initiated by the primary nucleon air collisions, the hadronic energy moments have been calculated from the CERN LEBCEHS data for pp collisions and FNAL data for ?p collisions. Pion production by secondary pions have been taken into account and the final total muon spectrum has been derived from pp rightarrow?± x, pp ? K± x, ?p ? ?± x channels. The Z-factors have been corrected for p-air collisions. We have adopted the constant values of ?p-air and ??-air crosssections which are 273 mb and 213 mb, respectively. The adopted inelastic cross-sections for pp and ?p interactions are 35 mb and 22 mb, respectively. The Q-G plasma correction of Z-factors have also been incorporated in the final form. The solution to the standard differential equation for mesons is considered for muon flux estimation from Ngenerations of the parent mesons. By this formulation vertical muon spectra from each element along with the total primary nucleon spectrum have been derived. We wanted to observe the different shape of the muon spectra evaluated from different elemental spectra and to make a comparative study of that. In this energy range (102 - 104 ) GeV we have observed that the majority of the total muon flux is coming from the proton spectra. The contribution from the other elemental spectra to the total muon flux is not at all comparable with that of proton spectra.

Mitra, M.; Molla, N. H.; Bhattacharyya, D. P.

426

Using Measured Variance of Skywave Radar Sea-Echo Power Spectra to Estimate Ionospheric Doppler Broadening of Mean Spectra.  

National Technical Information Service (NTIS)

A relation between ionospheric Doppler broadening of skywave sea-echo Doppler spectra and the normalized variance of such spectra is derived. It is shown that the normalized variance is largest at the first-order Bragg lines of the Doppler spectra, and va...

R. M. Jones J. P. Riley T. M. Georges

1984-01-01

427

Unconstrained ocean wave spectra retrieval from SAR SLC imagery  

NASA Astrophysics Data System (ADS)

A new approach for directional ocean wave spectra retrieval from synthetic aperture radar (SAR) single look complex (SLC) imagery is presented. This method takes the advantages of both Engen's cross spectra method and Lyzenga's unconstrained inversion method. It consists of following three main steps: (1) split-look processing and cross-spectra estimation of SLC imagery; (2) unconstrained iteration of ocean wave spectra with 180° direction ambiguity from real part of cross-spectra; (3) remove the 180° ambiguity from imaginary part of cross-spectra. Envisat ASAR data are used in cases studies. Wavelength, wave direction and significant wave height (SWH) are also derived from retrieved ocean wave spectra. Case studies with comparisons show that this method reaches better results than the one used by ESA. It can avoid the inherent error of the latter.

Yang, Jingsong; Wang, He; Zhang, Rong; Chen, Xiaoyan; Huang, Weigen

2008-12-01

428

WebSpectra: Problems in NMR and IR Spectroscopy  

NSDL National Science Digital Library

From the University of California at Los Angeles's Chemistry Department, WebSpectra provides chemistry students with a searchable library of Nuclear Magnetic Resonance (NMR) and Infrared (IR) spectroscopy problems. According to the makers of this innovative site, "Interpretation of spectra is a technique that requires practice - this site provides 1H NMR and 13C NMR, DEPT, COSY and IR spectra of various compounds for students to interpret." A set of instructional documents are entitled Solving Spectral Problems, Overview of NMR Spectroscopy, Notes on NMR Solvents, Types of NMR Spectra, Introduction to IR Spectra, and a Table of IR Absorptions. A wide variety of compounds and their spectra are available for interpretation and have been organized in categories from Beginning to Advanced. Spectrum for each compound may be magnified 16X by clicking on peaks. This is an outstanding learning tool for students coming to grips with interpreting NMR and IR spectra.

429

New LRS spectra for 356 bright IRAS sources  

SciTech Connect

The low-resolution spectra of all IRAS point sources with F(nu) (12 microns) greater than 40 Jy that were not included in the Atlas of Low-Resolution Spectra are presented. These have been classified into eight groups based upon the spectral morphology. Silicate emission spectra and red-continuum spectra associated with H II region sources form about 60 percent of this sample. All types of spectra in the LRS Atlas are represented in the sample except for emission-line sources. The spectra is used to test a recent classification scheme for IRAS sources based on broadband colors. The spectra are consistent with the classifications from the colors in most cases. 20 refs.

Volk, K.; Cohen, M. (SETI Institute, Mountain View, CA (USA); California Univ., Berkeley (USA); Jamieson Science and Engineering, Inc., Scotts Valley, CA (USA))

1989-09-01

430

Raman Spectra from Pesticides on the Surface of Fruits  

NASA Astrophysics Data System (ADS)

Raman spectra of several vegetables and fruits were studied by micro-Raman spectrometer (514.5 nm) and Near-infrared Fourier Transform Raman spectrometer (FTRaman). It is shown that at 514.5 nm excitation, most of the spectra are from that of carotene with some very strong fluorescence in some cases. While at 1064 nm wavelength excitation, the spectra from the different samples demonstrate different characteristic Raman spectra without fluorescence. We discuss the spectroscopic difference by the two excitation wavelengths, and the application of Raman spectra for detection of pesticides left on the surface of vegetables and fruits. Raman spectra of fruits and pesticides were successfully recorded, and using the FT-Raman spectra the pesticides left on the surface of the fruits can be detected conveniently.

Zhang, P. X.; Zhou, Xiaofang; Cheng, Andrew Y. S.; Fang, Yan

2006-01-01

431

Linear Analysis of Infrared CO Spectra  

NASA Astrophysics Data System (ADS)

The first overtone band v = 2 ? 0 of CO at 2.35 ?m is a powerful probe for studying interstellar gas in a variety of environments in the long sightlines toward the Galactic center (GC), in particular the intervening spiral arms and the Central Molecular Zone (CMZ). We have been observing this band of CO together with the fundamental band of H_3^+ at 3.5 - 4.0 ?m since the two bands give comparable absorption depths but are sensitive to different environments. The overtone CO band is essentially only a probe of dense clouds, while H_3^+, which is present in both diffuse and dense clouds, allows one to distinguish diffuse clouds from dense clouds, when both species are observed at high resolution. The foreground spiral arms show both spectra intensely, indicating dense clouds, while the CMZ contains significant amounts of both dense and diffuse gas. Last year we started to develop a linear program for quantitative analysis of the overtone CO spectra similar to our program for the H_3^+ spectrum. The linearity is employed in two ways. First, since the transition dipole moment of the v = 2 ? 0 band is very small, ?2-0 = 0.00651 Debye, the optical depth of the transition is orders of magnitude lower than radio and ultraviolet spectra and column densities can be obtained linearly from observed equivalent widths (integrated intensities) without the complications caused by radiation trapping in the radio and saturation in the ultraviolet. Second, we assume linearity in thermalization; that is, we ignore the effects of radiation trapping. This is a more serious neglect, but it is justified to some extent for the analysis of the gas in the CMZ because of the low CO column densities in the cloud clumps and the high velocity dispersion. Conditions for the applicability of the linear analysis and corrections to the approximation using the Sobolev escape probability method will be discussed. The calculation should also be applicable to the infrared CO fundamental band and even to the radio under some limited conditions. Oka, T., Geballe, T. R., Goto, M., Usuda, T., & McCall, B. J. 2005, ApJ, 632, 882 Geballe, T. R., & Oka, T. 2010, ApJ, 709, L70 Oka, T. & Epp, E. 2004, ApJ, 613, 349

Oka, Takeshi; Xiao, Han; Geballe, T. R.

2010-06-01

432

Turbulent velocity spectra in superfluid flows  

NASA Astrophysics Data System (ADS)

We present velocity spectra measured in three cryogenic liquid 4He steady flows: grid and wake flows in a pressurized wind tunnel capable of achieving mean velocities up to 5 m/s at temperatures above and below the superfluid transition, down to 1.7 K, and a ``chunk'' turbulence flow at 1.55 K, capable of sustaining mean superfluid velocities up to 1.3 m/s. Depending on the flows, the stagnation pressure probes used for anemometry are resolving from one to two decades of the inertial regime of the turbulent cascade. We do not find any evidence that the second-order statistics of turbulence below the superfluid transition differ from the ones of classical turbulence, above the transition.

Salort, J.; Baudet, C.; Castaing, B.; Chabaud, B.; Daviaud, F.; Didelot, T.; Diribarne, P.; Dubrulle, B.; Gagne, Y.; Gauthier, F.; Girard, A.; Hébral, B.; Rousset, B.; Thibault, P.; Roche, P.-E.

2010-12-01

433

Longslit Spectra of the Galaxy NGC 1569  

NASA Astrophysics Data System (ADS)

Longslit spectra of the starburst galaxy NGC 1569 are displayed. This ground-based data was acquired at the 90-inch telescope of the Steward Observatory (Kitt Peak, Arizona) in September 1998. Results for the red region of the spectrum are presented. The variation of ionization and gas density as a function of position in the galaxy are shown. The background stellar component of the galaxy is separated from the nebular emission spectrum. These ground-based results will be used with space-based data to be acquired by astronomers at South Carolina State University, the University of Maryland and Rice University as part of an approved Cycle 8 Hubble Space Telescope program.

Duenas, Ely

2000-11-01

434

Power spectra for deterministic chaotic dynamical systems  

NASA Astrophysics Data System (ADS)

We present results on the broadband nature of power spectra for large classes of discrete chaotic dynamical systems, including uniformly hyperbolic (Axiom A) diffeomorphisms and certain nonuniformly hyperbolic diffeomorphisms (such as the Hénon map). Our results also apply to noninvertible maps, including Collet-Eckmann maps. For such maps (even the nonmixing ones) and Hölder continuous observables, we prove that the power spectrum is analytic except for finitely many removable singularities, and that for typical observables the spectrum is nowhere zero. Indeed, we show that the power spectrum is bounded away from zero except for infinitely degenerate observables. For slowly mixing systems such as Pomeau-Manneville intermittency maps, where the power spectrum is at most finitely differentiable, nonvanishing of the spectrum remains valid provided the decay of correlations is summable.

Melbourne, Ian; Gottwald, Georg A.

2008-01-01

435

Raman spectra of strained bilayer graphene  

NASA Astrophysics Data System (ADS)

In the Raman spectra of strained single layer graphene, modified electron and phonon dispersions result in the splitting of the double resonance 2D Raman band. It originates from significant changes in the resonant conditions owing to both the distorted Dirac cones and anisotropic modifications of the phonon dispersion under uniaxial strains [D. Yoon et al., Phys. Rev. Lett. 106, 155502 (2011)]. In unstrained bilayer graphene, the Raman 2D band consists of 4 Lorentzian peaks corresponding to the double resonance Raman scattering processes between the two conduction bands and the two valance bands. Under uniaxial strain, each of the four peaks in the Raman 2D band. We examined the polarization behaviors of the split 2D band and analyzed using a model similar to the one used for single layer graphene.

Yoon, Duhee; Jegal, Sunyoung; Cho, Yujin; Son, Young-Woo; Cheong, Hyeonsik

2012-02-01

436

Optical absorption spectra of dications of carotenoids  

SciTech Connect

Quantitative optical absorption spectra of the cation radicals and the dications of canthaxanthin (I), {beta}carotene (II), 7`-cyano-7`-ethoxycarbonyl-7`-apo-{beta}-carotene (III), and 7`,7`-dimethyl-7`-apo-{beta}-carotene (IV) in dichloromethane solution are reported. Exclusive formation of dications occurs when the carotenoids are oxidized with ferric chloride. Addition of neutral carotenoid to the dications results in equilibrium formation of cation radicals. Oxidation with iodine in dichloromethane affords only cation radicals; electrochemical oxidation under suitable conditions yields both dications and cation radicals. Values of the optical parameters depend on the nature of the oxidative medium. The oscillator strengths calculated for gas phase cation radicals and dications of I-IV using the INDO/S method show the same trend as the experimental values. 31 refs., 4 figs., 2 tabs.

Jeevarajan, J.A.; Wei, C.C.; Jeevarajan, A.S.; Kispert, L.D. [Univ. of Alabama, Tuscaloosa, AL (United States)

1996-04-04

437

Vibrational spectra and DFT calculations of squalene  

NASA Astrophysics Data System (ADS)

The isoprenoid compound squalene is a building block molecule for the production of essential cellular molecules such as membrane sterols, has several therapeutic activities including anticancer properties, and has commercial applications for a variety of industries including the production of cosmetics. While the physical structure of squalene has been known for many years, a spectroscopic understanding of the squalene molecular structure and how these spectrometric properties relate to the physical squalene structure has yet to be reported. In the present work we present the Raman and infrared spectra of liquid squalene, complemented by DFT calculations. The molecule has 234 vibrational frequencies and these have been categorized according to the different types of vibrational modes present. The vibrational modes are highly mixed and these have been assigned for the more prominent infrared and Raman bands.

Chun, Hye Jin; Weiss, Taylor L.; Devarenne, Timothy P.; Laane, Jaan

2013-01-01

438

Chemical and isotopic determination from complex spectra  

SciTech Connect

Challenges for proliferation detection include remote, high- sensitivity detection of chemical effluents from suspect facilities and enhanced detection sensitivity for nuclear material. Both the identification of chemical effluents with lidar and enhanced nuclear material detection from radiation sensors involve determining constituents from complex spectra. In this paper, we extend techniques used to analyze time series to the analysis of spectral data. Pattern identification methods are applied to spectral data for domains where standard matrix inversion may not be suitable because of detection statistics. We use a feed-forward, back-propagation neural network in which the nodes of the input layer are fed with the observed spectral data. The nodes of the output layer contain the identification and concentration of the isotope or chemical effluent the sensor is to identify. We will discuss the neural network architecture, together with preliminary results obtained from the training process.

Zardecki, A.; Strittmatter, R.B.

1995-07-01

439

Radioactive sample effects on EDXRF spectra  

SciTech Connect

Energy dispersive X-ray fluorescence (EDXRF) is a rapid, straightforward method to determine sample elemental composition. A spectrum can be collected in a few minutes or less, and elemental content can be determined easily if there is adequate energy resolution. Radioactive alpha emitters, however, emit X-rays during the alpha decay process that complicate spectral interpretation. This is particularly noticeable when using a portable instrument where the detector is located in close proximity to the instrument analysis window held against the sample. A portable EDXRF instrument was used to collect spectra from specimens containing plutonium-239 (a moderate alpha emitter) and americium-241 (a heavy alpha emitter). These specimens were then analyzed with a wavelength dispersive XRF (WDXRF) instrument to demonstrate the differences to which sample radiation-induced X-ray emission affects the detectors on these two types of XRF instruments.

Worley, Christopher G [Los Alamos National Laboratory

2008-01-01

440

Towards simulation of high temperature methane spectra  

NASA Astrophysics Data System (ADS)

Methane plays a central role in gas layers of temperatures up to around 3000K in a number of astrophysical objects ranging from giant planets to brown dwarfs, over proto-solar nebulae, to several classes of cool stars. In order to model and analyse these objects correctly, an accurate and complete list of spectral lines at high temperature is demanded. Predicting high temperature spectra implies, however, predicting hot bands and thus modelling highly excited vibrational states. This is a real challenge in the case of methane. We report the preliminary results of a theoretical study combining the global effective Hamiltonian approach and its computational implementation (STDS package: http://www.u-bourgogne.fr/LPUB/ shTDS.html) with semi-quantitative statistical considerations.

Borysov, A.; Champion, J. P.; Jørgensen, U. G.; Wenger, C.

441

Simulations of Semiconductor Quantum Well Spectra  

NASA Astrophysics Data System (ADS)

A realistic description of semiconductor quantum wells has to include the disorder due to growth-related interface imperfections. Numerical calculations of spectra averaged over many disorder realizations describe satisfactorily macroscopic experiments and yield information on interface quality and structure. The underlying interplay of quantum mechanics and disorder -- leading to phenomena such as wavefunction localization and enhanced resonant back-scattering in ultra-fast optical experiments -- can be accessed by a statistical analysis of level correlations both in numerical simulations and microscopic experiments (near-field scanning optical microscopy NSOM.) We briefly describe recent experimental results and present in detail the numerical aspects related to the solution of the disorder Schrödinger equation and of quantum-mechanical transition matrix elements.

Runge, Erich; Savona, Vincenzo; Zimmermann, Roland

2001-06-01

442

Simulations of Semiconductor Quantum Well Spectra  

NASA Astrophysics Data System (ADS)

A realistic description of semiconductor quantum wells has to include the disorder due to growth-related interface imperfections. Numerical calculations of spectra averaged over many disorder realizations describe satisfactorily macroscopic experiments and yield information on interface quality and structure. The underlying interplay of quantum mechanics and disorder --- leading to phenomena such as wavefunction localization and enhanced resonant back-scattering in ultra-fast optical experiments --- can be accessed by a statistical analysis of level correlations both in numerical simulations and microscopic experiments (near-field scanning optical microscopy.) We briefly describe recent experimental results and present in detail the numerical aspects related to the solution of the disorder Schrödinger equation and of quantum-mechanical transition matrix elements.

Runge, Erich; Savona, Vincenzo; Zimmermann, Roland

2002-08-01

443

Ship structural response analysis spectra and statistics  

NASA Astrophysics Data System (ADS)

Wave loading of ships and maritime structures is a random process and the response of these structures is itself a random process. Much work has been undertaken to better understand the nature of waves and a number of existing techniques are described. Statistical and spectral analysis techniques may be used to quantify the wave loads and the corresponding structural responses. The relationship between the input load and response may then be determined through the use of response amplitude operators and the response of the structure to predicted lifetime extreme loads and fatigue loading then calculated. Standard wave spectra and directional spreading factors are used to enable the seaway to be described mathematically and several standard forms are discussed. The use of statistical methods enables the seaway to be described in terms of a limited number of parameters from which short term and long term probability distributions may be obtained. These distributions may then be used to enable extreme lifetime loads to be determined.

Phelps, Bernie P.

1995-08-01

444

Workshop to establish databases of carbohydrate spectra  

SciTech Connect

The workshop was organized to formulate guidelines for establishing spectral databases of complex carbohydrates. The databases will enable the scientific community to avoid the great waste of research effort and funds that frequently occurs when carbohydrate chemists are forced to duplicate the structural characterization of previously characterized complex carbohydrates. Chemists waste their effort on repetitive characterizations because in the absence of spectral databases they are unaware they are analyzing a known molecule until they have completely determined its structure. Chemists will be able to avoid much of this wasted effort when the collections of mass and of nuclear magnetic resonance (NMR) spectra initiated at the workshop are subsequently developed into searchable databases. Then scientists only need query the databases with the spectrum or with information defining the spectrum of an unidentified carbohydrate to find out if it has been previously characterized.

NONE

1995-12-31

445

Tunneling spectra simulation of interacting Majorana wires  

NASA Astrophysics Data System (ADS)

Recent tunneling experiments on InSb hybrid superconductor-semiconductor devices have provided hope for a stabilization of Majorana edge modes in a spin-orbit quantum wire subject to a magnetic field and superconducting proximity effect. Connecting the experimental scenario with a microscopic description poses challenges of a different kind, such as accounting for the effect of interactions on the tunneling properties of the wire. We develop a density matrix renormalization group (DMRG) analysis of the tunneling spectra of interacting Majorana chains, which we explicate for the Kitaev chain model. Our DMRG approach allows us to calculate the spectral function down to zero frequency, where we analyze how the Majorana zero-bias peak is affected by interactions. For topological phase transitions between the topological and trivial superconducting phase in the Majorana wire, the bulk gap closure generically affects the proximity peaks and the Majorana peak.

Thomale, Ronny; Rachel, Stephan; Schmitteckert, Peter

2013-10-01

446

Radiation Spectra and Polarization in Magnetar Bursts  

NASA Astrophysics Data System (ADS)

We present Monte Carlo simulations of radiative transfer in magnetar atmospheres. We include the effects of vacuum polarization, electron and proton scattering, and free-free absorption. Simulations are performed for the atmosphere model with the magnetic field perpendicular and also tilted with respect to the neutron star surface, and we show that the average spectrum does not strongly depend on the orientation of the magnetic field. We investigate the region of the parameter space where the vacuum absorption-like feature appears in the spectrum, and we analyze the shape of the proton cyclotron line. Our results indicate that the existence of the vacuum polarization feature should be a general attribute of soft gamma-ray repeaters' burst spectra, provided that the energy release takes place at a sufficiently dense region and the atmosphere scale height is large enough. We discuss the existence of such a feature in recent observational data on these sources.

Niemiec, Jacek; Bulik, Tomasz

2006-01-01

447

Prediction of electroencephalographic spectra from neurophysiology  

NASA Astrophysics Data System (ADS)

A recent neurophysical model of propagation of electrical waves in the cortex is extended to include a physiologically motivated subcortical feedback loop via the thalamus. The electroencephalographic spectrum when the system is driven by white noise is then calculated analytically in terms of physiological parameters, including the effects of filtering of signals by the cerebrospinal fluid, skull, and scalp. The spectral power at lo