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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

An Application of the Coda Methodology for Moment-Rate Spectra Using Broadband Stations in Turkey  

SciTech Connect

A recently developed coda magnitude methodology was applied to selected broadband stations in Turkey for the purpose of testing the coda method in a large, laterally complex region. As found in other, albeit smaller regions, coda envelope amplitude measurements are significantly less variable than distance-corrected direct wave measurements (i.e., L{sub g} and surface waves) by roughly a factor 3-to-4. Despite strong lateral crustal heterogeneity in Turkey, they found that the region could be adequately modeled assuming a simple 1-D, radially symmetric path correction. After calibrating the stations ISP, ISKB and MALT for local and regional distances, single-station moment-magnitude estimates (M{sub W}) derived from the coda spectra were in excellent agreement with those determined from multistation waveform modeling inversions, exhibiting a data standard deviation of 0.17. Though the calibration was validated using large events, the results of the calibration will extend M{sub W} estimates to significantly smaller events which could not otherwise be waveform modeled. The successful application of the method is remarkable considering the significant lateral complexity in Turkey and the simple assumptions used in the coda method.

Eken Tuna, Kevin Mayeda, Abraham Hofstetter, Rengin Gok, Gonca Orgulu, Niyazi Turkelli

2004-07-11

3

An unbiased measurement of the UV background and its evolution via the proximity effect in quasar spectra  

NASA Astrophysics Data System (ADS)

We investigated a set of high-resolution (R˜45 000), high signal-to-noise (S/N˜70) quasar spectra to search for the signature of the so-called proximity effect in the H I Ly? forest. The sample consists of 40 bright quasars with redshifts in the range 2.1 < z < 4.7. Using the flux transmission statistic, we determined the redshift evolution of the H I effective optical depth in the Lyman forest between 2? z? 4.5, finding good agreement with previous measurements based on smaller samples. We also see the previously reported dip in ?_eff(z) around redshift z˜ 3.3, but as the significance of that feature is only 2.6?, we consider this detection tentative. Comparing the flux transmission near each quasar with what was expected from the overall trend of ?_eff(z), we clearly detect the proximity effect not only in the combined quasar sample, but also towards each individual line of sight at high significance, albeit with varying strength. We quantify this strength using a simple prescription based on a fiducial value for the intensity of the metagalactic UV background (UVB) radiation field at 1 Ryd, multiplied by a free parameter that varies from QSO to QSO. The observed proximity effect strength distribution (PESD) is asymmetric, with an extended tail towards values corresponding to a weak effect. We demonstrate that this is not simply an effect of gravitational clustering around quasars, as the same asymmetry is already present in the PESD predicted for purely Poissonian variance in the absorption lines. We present the results of running the same analysis on simulated quasar spectra generated by a simple Monte-Carlo code. Comparing the simulated PESD with observations, we argue that the standard method of determining the UVB intensity J?_0 by averaging over several lines of sight is heavily biased towards high values of J?_0 because of the PESD asymmetry. Using instead the mode of the PESD provides an estimate of J?_0 that is unbiased with respect to his effect. For our sample we get a modal value for the UVB intensity of log J?_0 = -21.51± 0.15 (in units of erg cm-2 s-1 Hz-1 sr-1) for a median quasar redshift of 2.73. With J?_0 fixed we then corrected ?_eff near each quasar for local ionisation and estimated the amount of excess H I absorption attributed to gravitational clustering. On scales of ˜ 3 Mpc, only a small minority of quasars show substantial overdensities of up to a factor of a few in ?_eff; these are exactly the objects with the weakest proximity effect signatures. After removing those quasars residing in overdense regions, we redetermined the UVB intensity using a hybrid approach of sample averaging and statistical correction for the PESD asymmetry bias, arriving at log J?_0 = -21.46+0.14-0.21. This is the most accurate measurement of J?_0 to date. We present a new diagnostic based on the shape and width of the PESD that strongly supports our conclusion that there is no systematic overdensity bias for the proximity effect. This additional diagnostic breaks the otherwise unavoidable degeneracy of the proximity effect between UVB and overdensity. We then applied our hybrid approach to estimate the redshift evolution of the UVB intensity and found tentative evidence of a mild decrease in log J?_0 with increasing redshift, by a factor of ˜ 0.4 from z=2 to z=4. Our results are in excellent agreement with earlier predictions for the evolving UVB intensity, and they also agree well with other methods of estimating the UVB intensity. In particular, our measured UVB evolution is much slower than the change in quasar space densities between z=4 and z=2, supporting the notion of a substantial contribution of star-forming galaxies to the UVB at high redshift. Based on data collected at the European Southern Observatory and obtained from the ESO Science Archive. Appendix A is only available in electronic form at http://www.aanda.org

Dall'Aglio, A.; Wisotzki, L.; Worseck, G.

2008-11-01

4

Universal mean moment rate profiles of earthquake ruptures  

SciTech Connect

Earthquake phenomenology exhibits a number of power law distributions including the Gutenberg-Richter frequency-size statistics and the Omori law for aftershock decay rates. In search for a basic model that renders correct predictions on long spatiotemporal scales, we discuss results associated with a heterogeneous fault with long-range stress-transfer interactions. To better understand earthquake dynamics we focus on faults with Gutenberg-Richter-like earthquake statistics and develop two universal scaling functions as a stronger test of the theory against observations than mere scaling exponents that have large error bars. Universal shape profiles contain crucial information on the underlying dynamics in a variety of systems. As in magnetic systems, we find that our analysis for earthquakes provides a good overall agreement between theory and observations, but with a potential discrepancy in one particular universal scaling function for moment rates. We primarily use mean field theory for the theoretical analysis, since it has been shown to be in the same universality class as the full three-dimensional version of the model (up to logarithmic corrections). The results point to the existence of deep connections between the physics of avalanches in different systems.

Mehta, Amit P.; Dahmen, Karin A.; Ben-Zion, Yehuda [Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801-3080 (United States); Department of Earth Sciences, University of Southern California, Los Angeles, California 90089-0740 (United States)

2006-05-15

5

Spectra  

NSDL National Science Digital Library

Learners construct a spectroscope out of a shoe box or mailing tube, diffraction grating, and other simple materials. They then use their spectroscope to observe spectra, the colors that make up light. Learners compare the spectra of various light sources. Use this activity to introduce learners to basic principles of light and color. Also, look at a related page about auroras to understand how distinguishing spectra of different atoms helps scientists understand the universe.

Exploratorium, The

2012-06-26

6

Unbiased sampling of network ensembles  

E-print Network

Sampling random graphs with given properties is a key step in the analysis of networks, as random ensembles represent basic null models required to identify patterns such as communities and motifs. A key requirement is that the sampling process is unbiased and efficient. The main approaches are microcanonical, i.e. they sample graphs that exactly match the enforced constraints. Unfortunately, when applied to strongly heterogeneous networks (including most real-world graphs), the majority of these approaches become biased and/or time-consuming. Moreover, the algorithms defined in the simplest cases (such as binary graphs with given degrees) are not easily generalizable to more complicated ensembles. Here we propose a solution to the problem via the introduction of a `maximize-and-sample' (`Max & Sam') method to correctly sample ensembles of networks where the constraints are `soft' i.e. they are realized as ensemble averages. Being based on exact maximum-entropy distributions, our approach is unbiased by c...

Squartini, Tiziano; Garlaschelli, Diego

2014-01-01

7

Affine Constellations Without Mutually Unbiased Counterparts  

E-print Network

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, mostly in dimension six. The observed discrepancies make a deeper relation between the two existence problems unlikely.

Stefan Weigert; Thomas Durt

2010-07-22

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

A note on optimal vector unbiased predictor  

Microsoft Academic Search

A characterization of optimal vector unbiased predictor is obtained. Some properties of optimal unbiased predictors are established.\\u000a It is shown that simultaneous prediction of future random variables is equivalent to marginal prediction of these random variables.\\u000a Following Kale and Chandrasekar (1983) and Chandrasekar (1984), it is shown that the criteria proposed by ishii (1969) based\\u000a on matrices and the one

B. Chandrasekar; T. Edwin Prabakaran

1994-01-01

10

Unbiased estimation for sequential multinomial sampling plans  

Microsoft Academic Search

For sequential multinomial sampling, a sufficient condition for the stopping rule to be closed is obtained. And, by the application of the Rao-Blackwell method,an unbiased estimator based on the sufficient statistics is given for some functions of unknown parameters. The results are applied to some sequential stopping rules.

Ken-ichi Koike

1993-01-01

11

Seismic Moment Rate Function Inversions from Very Long Period Signals Associated with Strombolian Eruptions at Mount Erebus, Antarctica  

NASA Astrophysics Data System (ADS)

Mount Erebus, Antarctica, shows persistent Strombolian activity, principally in the form of impulsive eruptions of simple and very large (up to 10 m diameter) gas bubbles through its long-lived phonolitic lava lake. Eruptions produce oscillatory near-field very long period (VLP; ~8-20 s period) seismic signals due to processes occurring (seconds) before, during, and (up to several minutes) following the characteristic bubble bursts that mark the onset of short period (>1 Hz) seismoacoustic signals. Coupled broadband seismoacoustic and video analysis shows that this signal is associated with three corresponding component processes: 1) the bubble ascent phase characterized by gas/lava mass transport within the conduit system that can produce a positive or negative vertical rate of momentum change, depending on the event; 2) the eruptive evisceration of the lava lake to a depth of up to 10's of m in the explosive surface decompression of the gas bubble; 3) the refilling and reestablishment gravitational equilibrium within the conduit system. We employ a new method for efficiently solving the inverse problem of finding either independent or proportional moment-tensor element rate functions using three-component near-field seismograms recorded at multiple seismic stations. The method incorporates a frequency-domain deconvolution that, in its most general formulation, solves for six independent moment rate tensor force couple time functions plus a vertical force time function. We present an efficient scheme for solving this problem using conjugate gradient methods and apply it to Erebus VLP signals from the past several years of activity.

Lucero, C.; Aster, R. C.; Borchers, B.; Kyle, P.

2005-12-01

12

Unbiased search of minimal energy nanocluster structures  

NASA Astrophysics Data System (ADS)

A new strategy to find global minima is applied to the structure of metallic clusters. It consists in implementing a conformational space annealing (CSA) unbiased search in combination with many body phenomenological potential techniques to create a data bank of putative minima. Next, the clusters in this data bank are examined by first principle methods to obtain the minimum energy cluster. The scheme is successfully applied to magic number 13 atom clusters of rhodium, palladium and silver. Global minimum energy cluster structures not previously reported are found through our procedure.

Rogan, José; García, Griselda; Loyola, Claudia; Orellana, Walter; Ramírez, Ricardo; Kiwi, Miguel

2006-03-01

13

Are ‘unbiased ’ forecasts really unbiased? Another look at the Fed forecasts.  

E-print Network

Web: www.gwu.edu/~iiepAre 'unbiased ' forecasts really unbiased? Another look at the Fed forecasts This paper reconciles contradictory findings obtained from forecast evaluations: the existence of systematic errors and the failure to reject rationality in the presence of such errors. Systematic errors in one economic state may offset the opposite types of errors in the other state such that the null of rationality is not rejected. A modified test applied to the Fed forecasts shows that the forecasts were ex post biased. Are 'unbiased ' forecasts really unbiased? Another look at the Fed forecasts Monetary policy decisions are based on forecasts of future economic activity. It is for this reason that economists have evaluated the forecasts made by the staff of the Board of Governors of the Federal Reserve System in preparation for the Open Market Committee meetings. The forecasts are quarterly predictions made several times each quarter with horizons of one to eight periods. The staff predicts GDP, its components, various price indices, unemployment, etc. Previous evaluations have primarily focused on the predictions of real and nominal GDP

Tara Sinclair; Herman Stekler; Fred Joutz

2008-01-01

14

Unbiased Relatedness Estimation in Structured Populations  

PubMed Central

Knowledge of the genetic relatedness between individuals is important in many research areas in quantitative genetics, conservation genetics, forensics, evolution, and ecology. In the absence of pedigree records, relatedness can be estimated from genetic marker data using a number of estimators. These estimators, however, make the critical assumption of a large random mating population without genetic structures. The assumption is frequently violated in the real world where geographic/social structures or nonrandom mating usually lead to genetic structures. In this study, I investigated two approaches to the estimation of relatedness between a pair of individuals from a subpopulation due to recent common ancestors (i.e., relatedness is defined and measured with the current focal subpopulation as reference). The indirect approach uses the allele frequencies of the entire population with and without accounting for the population structure, and the direct approach uses the allele frequencies of the current focal subpopulation. I found by simulations that currently widely applied relatedness estimators are upwardly biased under the indirect approach, but can be modified to become unbiased and more accurate by using Wright's Fst to account for population structures. However, the modified unbiased estimators under the indirect approach are clearly inferior to the unmodified original estimators under the direct approach, even when small samples are used in estimating both allele frequencies and relatedness. PMID:21212234

Wang, Jinliang

2011-01-01

15

Decision rules for unbiased inventory estimates  

NASA Technical Reports Server (NTRS)

An efficient and accurate procedure for estimating inventories from remote sensing scenes is presented. In place of the conventional and expensive full dimensional Bayes decision rule, a one-dimensional feature extraction and classification technique was employed. It is shown that this efficient decision rule can be used to develop unbiased inventory estimates and that for large sample sizes typical of satellite derived remote sensing scenes, resulting accuracies are comparable or superior to more expensive alternative procedures. Mathematical details of the procedure are provided in the body of the report and in the appendix. Results of a numerical simulation of the technique using statistics obtained from an observed LANDSAT scene are included. The simulation demonstrates the effectiveness of the technique in computing accurate inventory estimates.

Argentiero, P. D.; Koch, D.

1979-01-01

16

Mutually unbiased bases and bound entanglement  

NASA Astrophysics Data System (ADS)

In this contribution we relate two different key concepts: mutually unbiased bases (MUBs) and entanglement. We provide a general toolbox for analyzing and comparing entanglement of quantum states for different dimensions and numbers of particles. In particular we focus on bound entanglement, i.e. highly mixed states which cannot be distilled by local operations and classical communications. For a certain class of states—for which the state-space forms a ‘magic’ simplex—we analyze the set of bound entangled states detected by the MUB criterion for different dimensions d and number of particles n. We find that the geometry is similar for different d and n, consequently the MUB criterion opens possibilities to investigate the typicality of positivity under partial transposition (PPT)-bound and multipartite bound entanglement more deeply and provides a simple experimentally feasible tool to detect bound entanglement.

Hiesmayr, Beatrix C.; Löffler, Wolfgang

2014-04-01

17

Mutually unbiased bases and semi-definite programming  

NASA Astrophysics Data System (ADS)

A complex Hilbert space of dimension six supports at least three but not more than seven mutually unbiased bases. Two computer-aided analytical methods to tighten these bounds are reviewed, based on a discretization of parameter space and on Gröbner bases. A third algorithmic approach is presented: the non-existence of more than three mutually unbiased bases in composite dimensions can be decided by a global optimization method known as semidefinite programming. The method is used to confirm that the spectral matrix cannot be part of a complete set of seven mutually unbiased bases in dimension six.

Brierley, Stephen; Weigert, Stefan

2010-11-01

18

The FIRST Unbiased Survey for Radio Sources  

NASA Astrophysics Data System (ADS)

Of the 100,000 brightest sources in the radio sky, fewer than 20 are stars. Nonetheless, as a consequence of targeted searches of optically selected samples, nearly 1000 sources of stellar radio emission have been identified since the advent 25 years ago of sensitive radio interferometers operating at centimeter wavelengths. Stellar objects with high radio luminosities include dMe flare stars, rapidly rotating young stars, some pre- and post-main sequence stars, and various classes of close binary systems. To date, however, no radio survey has had the sensitivity and astrometric accuracy to produce a radio-selected stellar sample. The VLA FIRST radio survey, now complete over 5000 square degrees, provides the first such sample to a sub-millijansky threshold. We have compared the FIRST catalog with the Hipparcos and Tycho catalogs of bright stars, as well as with other stellar catalogs with the requisite proper motion information. Several dozen radio stars are detected, more than tripling the number of known radio stars in our survey region. Many of these sources are shown to be highly variable through comparison of observations in the overlap regions of the FIRST pointing grid. We find additional stellar radio emitters at fainter flux densities by comparing the Hipparcos and Tycho positions directly to the FIRST images. We quantify the increase in stellar identifications that the GSC II catalog will provide, and discuss the implications for stellar radio luminosity functions that this FIRST unbiased survey for radio stars provides. The FIRST project is supported by grants from the National Geographic Society, the National Science Foundation, NATO, IGPP, Columbia University, and Sun Microsystems.

Helfand, D. J.; Schnee, S.; Becker, R. H.; White, R. L.; McMahon, R. G.

1997-12-01

19

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

20

Unbiased estimators of wildlife population densities using aural information  

E-print Network

UNBIASED ESTIMATORS OF WILDLIFE POPULATION DENSITIES USING AURAL INFORMATION A Thesis by ERIC NEWTON DURLAND Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree MASTER OF SCIENCE... May 1969 Ma]or Sub]ect: Statistics UNBIASED ESTIMATORS OF WILDLIFE POPULATION DENSITIES USING AURAL INFORMATION A Thesis by ERIC NEWTON DURLAND Approved as to sty1e and content by: (Chairm n of gommittee) Head of Departmen (Member) (Memb r...

Durland, Eric Newton

1969-01-01

21

Unbiased Identification of Nonlinear Sorption Characteristics by Soil Column Breakthrough  

E-print Network

Unbiased Identification of Nonlinear Sorption Characteristics by Soil Column Breakthrough breakthrough as case studies, possi­ ble applications of the new approach will be shown and its features, the column effluent concentration history, i.e. the breakthrough curve, is analyzed employing either

Gugat, Martin

22

Unbiased Protein Interface Prediction Based on Ligand Diversity Quantification  

E-print Network

.Nebel@kingston.ac.uk Abstract Proteins interact with each other to perform essential functions in cells. Consequently) is essential for the functionality of living cells. Alterations of these interactions affect biochemicalUnbiased Protein Interface Prediction Based on Ligand Diversity Quantification Reyhaneh

Nebel, Jean-Christophe

23

Blue Moon sampling, vectorial reaction coordinates, and unbiased constrained dynamics  

E-print Network

Blue Moon sampling, vectorial reaction coordinates, and unbiased constrained dynamics Giovanni force in terms of a conditional expectation which can be computed by Blue Moon sampling Introduction Fifteen years ago the Blue Moon ensemble method was introduced to sample rare events that occur

Van Den Eijnden, Eric

24

Three Ways to Look at Mutually Unbiased Bases  

SciTech Connect

This is a review of the problem of Mutually Unbiased Bases in finite dimensional Hilbert spaces, real and complex. Also a geometric measure of ''mubness'' is introduced, and applied to some explicit calculations in six dimensions (partly done by Bjoerck and by Grassl). Although this does not yet solve any problem, some appealing structures emerge.

Bengtsson, Ingemar [Fysikum, Stockholm University, 106 91 Stockholm (Sweden)

2007-02-21

25

Self-consistent, unbiased root-mean-square emittanceanalysis  

SciTech Connect

We present a self-consistent method for analyzing measured emittance data that yields unbiased estimates for the root-mean-square(rms) emittance. The self-consistent, unbiased elliptical exclusion analysis uses an ellipse to determine the bias from the data outside the ellipse, before calculating the rms emittance from the bias-subtracted data within the ellipse. Increasing the ellipse size until the rms emittance estimate saturates allows for determining the minimum elliptical area that includes all real signals, even those buried in the noise. Variations of the ellipse shape and orientations are used to test the robustness of the results. Background fluctuations cause fluctuations in the rms emittance estimate, which are an estimate of the uncertainty incurred through the analysis.

Stockli, Martin P.; Welton, R.F.; Keller, R.

2003-09-11

26

Unbiased Estimation of Refractive State of Aberrated Eyes  

PubMed Central

To identify unbiased methods for estimating the target vergence required to maximize visual acuity based on wavefront aberration measurements. Experiments were designed to minimize the impact of confounding factors that have hampered previous research. Objective wavefront refractions and subjective acuity refractions were obtained for the same monochromatic wavelength. Accommodation and pupil fluctuations were eliminated by cycloplegia. Unbiased subjective refractions that maximize visual acuity for high contrast letters were performed with a computer controlled forced choice staircase procedure, using 0.125 diopter steps of defocus. All experiments were performed for two pupil diameters (3mm and 6mm). As reported in the literature, subjective refractive error does not change appreciably when the pupil dilates. For 3 mm pupils most metrics yielded objective refractions that were about 0.1D more hyperopic than subjective acuity refractions. When pupil diameter increased to 6 mm, this bias changed in the myopic direction and the variability between metrics also increased. These inaccuracies were small compared to the precision of the measurements, which implies that most metrics provided unbiased estimates of refractive state for medium and large pupils. A variety of image quality metrics may be used to determine ocular refractive state for monochromatic (635nm) light, thereby achieving accurate results without the need for empirical correction factors. PMID:21777601

Martin, Jesson; Vasudevan, Balamurali; Himebaugh, Nikole; Bradley, Arthur; Thibos, Larry

2011-01-01

27

Unbiased Water and Methanol Maser Surveys of NGC 1333  

NASA Astrophysics Data System (ADS)

We present the results of unbiased 22 GHz H2O water and 44 GHz class I CH3OH methanol maser surveys in the central 7' × 10' area of NGC 1333 and two additional mapping observations of a 22 GHz water maser in a ~3' × 3' area of the IRAS4A region. In the 22 GHz water maser survey of NGC 1333 with a sensitivity of ? ~ 0.3 Jy, we confirmed the detection of masers toward H2O(B) in the region of HH 7-11 and IRAS4B. We also detected new water masers located ~20'' away in the western direction of IRAS4B or ~25'' away in the southern direction of IRAS4A. We could not, however, find young stellar objects or molecular outflows associated with them. They showed two different velocity components of ~0 and ~16 km s-1, which are blue- and redshifted relative to the adopted systemic velocity of ~7 km s-1 for NGC 1333. They also showed time variabilities in both intensity and velocity from multi-epoch observations and an anti-correlation between the intensities of the blue- and redshifted velocity components. We suggest that the unidentified power source of these masers might be found in the earliest evolutionary stage of star formation, before the onset of molecular outflows. Finding this kind of water maser is only possible through an unbiased blind survey. In the 44 GHz methanol maser survey with a sensitivity of ? ~ 0.5 Jy, we confirmed masers toward IRAS4A2 and the eastern shock region of IRAS2A. Both sources are also detected in 95 and 132 GHz methanol maser lines. In addition, we had new detections of methanol masers at 95 and 132 GHz toward IRAS4B. In terms of the isotropic luminosity, we detected methanol maser sources brighter than ~5 × 1025 erg s-1 from our unbiased survey.

Lyo, A.-Ran; Kim, Jongsoo; Byun, Do-Young; Lee, Ho-Gyu

2014-11-01

28

Unitarily inequivalent mutually unbiased bases for n qubits  

NASA Astrophysics Data System (ADS)

The standard construction of complete sets of mutually unbiased bases (MUBs) in prime power dimensions is based on the quadratic Gauss sums. We introduce complete MUB sets for three, four, and five qubits that are unitarily inequivalent to all existing MUB sets. These sets are constructed by using certain exponential sums, where the degree of the polynomial appearing in the exponent can be higher than 2. Every basis of these MUBs (except the computational) consists of two disjoint blocks of vectors with different factorization structures and associated with a unique hypergraph (or graph) that represents an interaction between the qubits.

Sehrawat, Arun; Klimov, Andrei B.

2014-12-01

29

Unbiased Estimation of Mutation Rates under Fluctuating Final Counts  

PubMed Central

Estimation methods for mutation rates (or probabilities) in Luria-Delbrück fluctuation analysis usually assume that the final number of cells remains constant from one culture to another. We show that this leads to systematically underestimate the mutation rate. Two levels of information on final numbers are considered: either the coefficient of variation has been independently estimated, or the final number of cells in each culture is known. In both cases, unbiased estimation methods are proposed. Their statistical properties are assessed both theoretically and through Monte-Carlo simulation. As an application, the data from two well known fluctuation analysis studies on Mycobacterium tuberculosis are reexamined. PMID:24988217

Ycart, Bernard; Veziris, Nicolas

2014-01-01

30

Unbiased Approaches to Biomarker Discovery in Neurodegenerative Diseases.  

PubMed

Neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and frontotemporal dementia have several important features in common. They are progressive, they affect a relatively inaccessible organ, and we have no disease-modifying therapies for them. For these brain-based diseases, current diagnosis and evaluation of disease severity rely almost entirely on clinical examination, which may be only a rough approximation of disease state. Thus, the development of biomarkers-objective, relatively easily measured, and precise indicators of pathogenic processes-could improve patient care and accelerate therapeutic discovery. Yet existing, rigorously tested neurodegenerative disease biomarkers are few, and even fewer biomarkers have translated into clinical use. To find new biomarkers for these diseases, an unbiased, high-throughput screening approach may be needed. In this review, I will describe the potential utility of such an approach to biomarker discovery, using Parkinson's disease as a case example. PMID:25442938

Chen-Plotkin, Alice S

2014-11-01

31

[Open questions in neurotransplantation. Attempted at an unbiased ethical analysis].  

PubMed

Neurotransplantation utilizing fetal (embryonic) tissue for treating Morbus Parkinson is a matter of ethical debate, among professionals as well as the public at large. Here, we take a systematic approach to the questions raised to facilitate an unbiased ethical analysis and to attempt adequate answers. Possible functions of ethics in medicine, principles of ethical reflexion in medicine and perspectives of ethical reflexion are differentiated resp. combined. Relevant areas of ethical conflict may thus be identified separating at the same time the context of explantation from that of implantation. Taking as our starting point a systematic discussion of the various open questions, we put forward 5 conclusions. These should help clarify under which conditions the therapy model of neurotransplantation will be admissible. PMID:8571696

Reiter-Theil, S

1995-01-01

32

All-optical injection of ballistic electrical currents in unbiased silicon  

E-print Network

LETTERS All-optical injection of ballistic electrical currents in unbiased silicon LOUIS COSTA all-optical generation of ultrafast ballistic electrical currents in clean, unbiased, bulk silicon. For electrical-current generation in Si, we use 150 fs pulses with 0.69

Loss, Daniel

33

High levels of absorption in orientation-unbiased, radio-selected 3CR Active Galaxies  

NASA Astrophysics Data System (ADS)

A critical problem in understanding active galaxies (AGN) is the separation of intrinsic physical differences from observed differences that are due to orientation. Obscuration of the active nucleus is anisotropic and strongly frequency dependent leading to complex selection effects for observations in most wavebands. These can only be quantified using a sample that is sufficiently unbiased to test orientation effects. Low-frequency radio emission is one way to select a close-to orientation-unbiased sample, albeit limited to the minority of AGN with strong radio emission.Recent Chandra, Spitzer and Herschel observations combined with multi-wavelength data for a complete sample of high-redshift (1 24.2) = 2.5:1.4:1 in these high-luminosity (log L(0.3-8keV) ~ 44-46) sources. These ratios are consistent with current expectations based on modelingthe Cosmic X-ray Background. A strong correlation with radio orientation constrains the geometry of the obscuring disk/torus to have a ~60 degree opening angle and ~12 degree Compton-thick cross-section. The deduced ~50% obscured fraction of the population contrasts with typical estimates of ~20% obscured in optically- and X-ray-selected high-luminosity samples. Once the primary nuclear emission is obscured, AGN X-ray spectra are frequently dominated by unobscured non-nuclear or scattered nuclear emission which cannot be distinguished from direct nuclear emission with a lower obscuration level unless high quality data is available. As a result, both the level of obscuration and the estimated instrinsic luminosities of highly-obscured AGN are likely to be significantly (*10-1000) underestimated for 25-50% of the population. This may explain the lower obscured fractions reported for optical and X-ray samples which have no independent measure of the AGN luminosity. Correcting AGN samples for these underestimated luminosities would result in flatter derived luminosity functions and potentially change their evolution.

Wilkes, Belinda J.; Haas, Martin; Barthel, Peter; Leipski, Christian; Kuraszkiewicz, Joanna; Worrall, Diana; Birkinshaw, Mark; Willner, Steven P.

2014-08-01

34

X-ray Properties of an Unbiased Hard X-ray Detected Sample of AGN  

NASA Technical Reports Server (NTRS)

The SWIFT gamma ray observatory's Burst Alert Telescope (BAT) has detected a sample of active galactic nuclei (AGN) based solely on their hard X-ray flux (14-195keV). In this paper, we present for the first time XMM-Newton X-ray spectra for 22 BAT AGXs with no previously analyzed X-ray spectra. If our sources are a representative sample of the BAT AGN, as we claim, our results present for the first time global X-ray properties of an unbiased towards absorption (n(sub H) < 3 x 10(exp 25)/sq cm), local (< z >= 0.03), AGN sample. We find 9/22 low absorption (n(sub H) < 10(exp 23)/sq cm), simple power law model sources, where 4 of these sources have a statistically significant soft component. Among these sources, we find the presence of a warm absorber statistically significant for only one Seyfert 1 source, contrasting with the ASCA results of Reynolds (1997) and George et al. (1998), who find signatures of warm absorption in half or more of their Seyfert 1 samples at similar redshifts. Additionally, the remaining sources (13122) have more complex spectra, well-fit by an absorbed power law at E > 2.0 keV. Five of the complex sources (NGC 612, ESO 362-G018, MRK 417, ESO 506-G027, and NGC 6860) are classified as Compton-thick candidates. Further, we find four more sources (SWIFT J0641.3+3257, SWIFT J0911.2+4533, SWIFT J1200.8+0650, and NGC 4992) with properties consistent with the hidden/buried AGN reported by Ueda et al. (2007). Finally, we include a comparison of the XMM EPIC spectra with available SWIFT X-ray Telescope (XRT) observations. From these comparisons, we find 6/16 sources with varying column densities, 6/16 sources with varying power law indices, and 13/16 sources with varying fluxes, over periods of hours to months. Flux and power law index are correlated for objects where both parameters vary.

Winter, Lisa M.; Mushotzky, Richard F.; Tueller, Jack; Markwardt, Craig

2007-01-01

35

Unbiased water and methanol maser surveys of NGC 1333  

E-print Network

We present the results of unbiased 22 GHz H2O water and 44 GHz class I CH3OH methanol maser surveys in the central 7x10 arcmin area of NGC 1333 and two additional mapping observations of a 22 GHz water maser in a ~3x3arcmin area of the IRAS4A region. In the 22 GHz water maser survey of NGC 1333 with sensitivity of sigma~0.3Jy, we confirmed masers toward H2O(B) in the region of HH 7-11 and IRAS4B. We also detected new water masers at ~20arcsec away in the western direction of IRAS4B or ~25arcsec away in the southern direction of IRAS4A. We could not however find young stellar objects or molecular outflows associated with them. They showed two different velocity components of ~0 and ~16 km/s, which are blue- and red-shifted relative to the adopted systemic velocity of ~7 km/s for NGC 1333. They also showed time variabilities in both intensity and velocity from multi-epoch observations and an anti-correlation between the intensities of the blue- and the red-shifted velocity components. We suggest that the uniden...

Lyo, A-Ran; Byun, Do-Young; Lee, Ho-Gyu

2014-01-01

36

Depicting qudit quantum mechanics and mutually unbiased qudit theories  

E-print Network

We generalize the ZX calculus to quantum systems of dimension higher than two. The resulting calculus is sound and universal for quantum mechanics. We define the notion of a mutually unbiased qudit theory and study two particular instances of these theories in detail: qudit stabilizer quantum mechanics and Spekkens-Schreiber toy theory for dits. The calculus allows us to analyze the structure of qudit stabilizer quantum mechanics and provides a geometrical picture of qudit stabilizer theory using D-toruses, which generalizes the Bloch sphere picture for qubit stabilizer quantum mechanics. We also use our framework to describe generalizations of Spekkens toy theory to higher dimensional systems. This gives a novel proof that qudit stabilizer quantum mechanics and Spekkens-Schreiber toy theory for dits are operationally equivalent in three dimensions. The qudit pictorial calculus is a useful tool to study quantum foundations, understand the relationship between qubit and qudit quantum mechanics, and provide a novel, high level description of quantum information protocols.

André Ranchin

2014-12-30

37

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

38

Estimating unbiased phenological trends by adapting site-occupancy models.  

PubMed

As a response to climate warming, many animals and plants have been found to shift phenologies, such as appearance in spring or timing of reproduction. However, traditional measures for shifts in phenology that are based on observational data likely are biased due to a large influence of population size, observational effort, starting date of a survey, or other causes that may affect the probability of detecting a species. Understanding phenological responses of species to climate change, however, requires a robust measure that could be compared among studies and study years. Here, we developed a new method for estimating arrival and departure dates based on site-occupancy models. Using simulated data, we show that our method provided virtually unbiased estimates of phenological events even if detection probability or the number of sites occupied by the species is changing over time. To illustrate the flexibility of our method, we analyzed spring arrival of two long-distance migrant songbirds and the length of the flight period of two butterfly species, using data from a long-term biodiversity monitoring program in Switzerland. In contrast to many birds that migrate short distances, the two long-distance migrant songbirds tended to postpone average spring arrival by -0.5 days per year between 1995 and 2012. Furthermore, the flight period of the short-distance-flying butterfly species apparently became even shorter over the study period, while the flight period of the longer-distance-flying butterfly species remained relatively stable. Our method could be applied to temporally and spatially extensive data from a wide range of monitoring programs and citizen science projects, to help unravel how species and communities respond to global warming. PMID:25230466

Roth, Tobias; Strebel, Nicolas; Amrhein, Valentin

2014-08-01

39

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. PMID:20656036

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

2010-01-01

40

Unbiased average age-appropriate atlases for pediatric studies.  

PubMed

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. PMID:20656036

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

2011-01-01

41

Quantitative and unbiased analysis of directional persistence in cell migration.  

PubMed

The mechanism by which cells control directional persistence during migration is a major question. However, the common index measuring directional persistence, namely the ratio of displacement to trajectory length, is biased, particularly by cell speed. An unbiased method is to calculate direction autocorrelation as a function of time. This function depends only on the angles of the vectors tangent to the trajectory. This method has not been widely used, because it is more difficult to compute. Here we discuss biases of the classical index and introduce a custom-made open-source computer program, DiPer, which calculates direction autocorrelation. In addition, DiPer also plots and calculates other essential parameters to analyze cell migration in two dimensions: it displays cell trajectories individually and collectively, and it calculates average speed and mean square displacements (MSDs) to assess the area explored by cells over time. This user-friendly program is executable through Microsoft Excel, and it generates plots of publication-level quality. The protocol takes ?15 min to complete. We have recently used DiPer to analyze cell migration of three different mammalian cell types in 2D cultures: the mammary carcinoma cell line MDA-MB-231, the motile amoeba Dictyostelium discoideum and fish-scale keratocytes. DiPer can potentially be used not only for random migration in 2D but also for directed migration and for migration in 3D (direction autocorrelation only). Moreover, it can be used for any types of tracked particles: cellular organelles, bacteria and whole organisms. PMID:25033209

Gorelik, Roman; Gautreau, Alexis

2014-08-01

42

The Meta-Analysis Effect Size Calculator: A Basic Program for Reconstructing Unbiased Effect Sizes  

Microsoft Academic Search

The Meta-Analysis Effect Size Calculator provides the user with many different ways to calculate an effect size depending on the information available in the original research report. In addition, the program computes an unbiased estimate of effect size.

William L. Curlette

1987-01-01

43

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

44

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

45

Unbiased statistical analysis for multi-stage proteomic search strategies.  

PubMed

"Multi-stage" search strategies have become widely accepted for peptide identification and are implemented in a number of available software packages. We describe limitations of these strategies for validation and decoy-based statistical analyses and demonstrate these limitations using a set of control sample spectra. We propose a solution that corrects the statistical deficiencies and describe its implementation using the open-source software X!Tandem. PMID:19947654

Everett, Logan J; Bierl, Charlene; Master, Stephen R

2010-02-01

46

atomic spectra 1 Atomic Spectra  

E-print Network

Physics, pp. 88-93 (Rutherford nuclear model), 93-106 (atomic structure and electron spectra) 2. D. W 3. Beiser: Concepts of Modern Physics, pp. 131-161 (atomic structure and electron spectra) 4. E. Lamb, Jr. and R. C. Retherford: The Structure of the Hydrogen Atom by a Microwave Method, Phys

Glashausser, Charles

47

There is no generalization of known formulas for mutually unbiased bases  

E-print Network

In a quantum system having a finite number $N$ of orthogonal states, two orthonormal bases $\\{a_i\\}$ and $\\{b_j\\}$ are called mutually unbiased if all inner products $$ have the same modulus $1/\\sqrt{N}$. This concept appears in several quantum information problems. The number of pairwise mutually unbiased bases is at most $N+1$ and various constructions of $N+1$ such bases have been found when $N$ is a power of a prime number. We study families of formulas that generalize these constructions to arbitrary dimensions using finite rings.We then prove that there exists a set of $N+1$ mutually unbiased bases described by such formulas, if and only if $N$ is a power of a prime number.

Claude archer

2003-12-26

48

Unbiased Estimation of Reliability in StressStrength Model and Similar Problems  

E-print Network

SPb. Math. Society Preprint 2000­03 28 Mar 2000 Unbiased Estimation of Reliability in Stress Petersburg, Russia VASSILY G. VOINOV Kazakhstan Institute of Management, Economics and Strategic Research for sampling inspection, lifetime and reliability testing are discussed. Continuous and discrete, univariate

49

An Unbiased Kalman Consensus Algorithm Mehdi Alighanbari and Jonathan P. How  

E-print Network

An Unbiased Kalman Consensus Algorithm Mehdi Alighanbari and Jonathan P. How Aerospace Controls proposed distributed planning schemes. Kalman filtering approaches to the consensus problem have been solution, if it had been computed. A modification to the basic algorithm is presented to ensure the Kalman

How, Jonathan P.

50

Genet Epidemiol . Author manuscript PEL: an unbiased method for estimating age-dependent genetic disease  

E-print Network

Genet Epidemiol . Author manuscript Page /1 11 PEL: an unbiased method for estimating age-dependent genetic disease risk from pedigree data unselected for family history Flora Alarcon 1 * , Catherine: Flora Alarcon Abstract Providing valid risk estimates of a genetic disease

Paris-Sud XI, Université de

51

PEL: An unbiased method for estimating age dependent genetic disease risk from pedigree data unselected  

E-print Network

1 PEL: An unbiased method for estimating age dependent genetic disease risk from pedigree data of a genetic disease with variable age of onset is a major challenge for prevention strategies. When data, Villejuif, France (2) INSERM, U535, Villejuif, France (3) Genetic Oncology, Institut curie, Paris, France (4

Paris-Sud XI, Université de

52

ON UNBIASED ESTIMATION OF SPARSE VECTORS CORRUPTED BY GAUSSIAN NOISE Alexander Junga  

E-print Network

to predict the threshold region of practical estimators. Index Terms-- Unbiased estimation, sparsity in order to exclude approaches such This work was supported by the FWF under Grant S10603-N13 (Statistical Inference) within the National Research Network SISE, by the WWTF under Grant MA 07-004 (SPORTS

Eldar, Yonina

53

Estimating Unbiased Treatment Effects in Education Using a Regression Discontinuity Design  

ERIC Educational Resources Information Center

The ability of regression discontinuity (RD) designs to provide an unbiased treatment effect while overcoming the ethical concerns plagued by Random Control Trials (RCTs) make it a valuable and useful approach in education evaluation. RD is the only explicitly recognized quasi-experimental approach identified by the Institute of Education…

Smith, William C.

2014-01-01

54

Sign-Sign Algorithm for Unbiased IIR Filtering in Impulsive Noise  

E-print Network

Sign-Sign Algorithm for Unbiased IIR Filtering in Impulsive Noise H. C. So Department of Computer : ithcso@cityu.edu.hk February 22, 2006 Index terms : Adaptive Algorithm, Infinite Impulse Response Filtering, Impulsive Noise Abstract : A new equation-error based sign-sign algorithm, which is derived from

So, Hing-Cheung

55

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.

56

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

57

Reconstruction of bipartite states via unambiguous state discrimination and mutually unbiased measurement  

NASA Astrophysics Data System (ADS)

We propose a scheme for reconstructing an unknown two-particle mixed state by means of unambiguous state discrimination. In this protocol, an ancillary particle is introduced for distinguishing four nonorthogonal states. The discrimination process is performed by a bipartite unitary operation on the two-particle system and the ancilla followed by a von Neumann measurement on the ancilla. Then the original two-particle system is measured in mutually unbiased bases. Consequently, the two-particle mixed state can be reconstructed. Furthermore, the total number of measurements in this protocol is less than that of the standard quantum tomography, thus the quantum resources is saved. Additionally, the nonorthogonal states discrimination and mutually unbiased measurement can be experimentally achieved, therefore our protocol may be realized with the current technology.

Han, Lian-Fang; Yang, Ming; Fang, Shu-Dong; Cao, Zhuo-Liang

2015-01-01

58

Contextual classification of multispectral image data: An unbiased estimator for the context distribution  

NASA Technical Reports Server (NTRS)

A key input to a statistical classification algorithm, which exploits the tendency of certain ground cover classes to occur more frequently in some spatial context than in others, is a statistical characterization of the context: the context distribution. An unbiased estimator of the context distribution is discussed which, besides having the advantage of statistical unbiasedness, has the additional advantage over other estimation techniques of being amenable to an adaptive implementation in which the context distribution estimate varies according to local contextual information. Results from applying the unbiased estimator to the contextual classification of three real LANDSAT data sets are presented and contrasted with results from non-contextual classifications and from contextual classifications utilizing other context distribution estimation techniques.

Tilton, J. C.; Swain, P. H. (principal investigators); Vardeman, S. B.

1981-01-01

59

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

E-print Network

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 classical 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 up to a dimension of d = 4.

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

2014-02-24

60

A one locus, biased mutation model and its equivalence to an unbiased model.  

PubMed

Experimental data suggests that for some continuously-varying characters under stabilising selection, mutation may cause a mean change in the value of the character. A one locus, mathematical model of a continuously-varying biological character with this property of biased mutation is investigated. Via a mathematical transformation, the equilibrium equation describing a large population of individuals is reduced to the equilibrium equation describing a mutationally unbiased problem. Knowledge of an unbiased problem is thus sufficient to determine all equilibrium properties of the corresponding biased problem. In the biased mutation problem, the dependence of the mean equilibrium value of the character, as a function of the mutational bias, is non-monotonic and remains small, for all levels of mutational bias. The analysis presented in this work sheds new light on Turelli's House of Cards Approximation. PMID:15555761

Waxman, D; Peck, J R

2004-12-01

61

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

2011-04-01

62

Comment on “Unbiased Statistical Analysis for Multi-Stage Proteomic Search Strategies”  

PubMed Central

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.

2013-01-01

63

Structure of the sets of mutually unbiased bases with cyclic symmetry  

NASA Astrophysics Data System (ADS)

Mutually unbiased bases that can be cyclically generated by a single unitary operator are of special interest, for they can be readily implemented in practice. We show that, for a system of qubits, finding such a generator can be cast as the problem of finding a symmetric matrix over the field {F}2 equipped with an irreducible characteristic polynomial of a given Fibonacci index. The entanglement structure of the resulting complete sets is determined by two additive matrices of the same size.

Seyfarth, U.; Sánchez-Soto, L. L.; Leuchs, G.

2014-11-01

64

Increasing the security of the ping-pong protocol by using many mutually unbiased bases  

E-print Network

In this paper we propose an extended version of the ping-pong protocol and study its security. The proposed protocol incorporates the usage of mutually unbiased bases in the control mode. We show that, by increasing the number of bases, it is possible to improve the security of this protocol. We also provide the upper bounds on eavesdropping average non-detection probability and propose a control mode modification that increases the attack detection probability.

Piotr Zawadzki; Zbigniew Pucha?a; Jaros?aw Adam Miszczak

2012-04-11

65

Increasing the security of the ping-pong protocol by using mutually unbiased bases  

E-print Network

In this paper we propose an extended version of the ping-pong protocol and study its security. The proposed protocol incorporates the usage of mutually unbiased bases in the control mode. We show that, by increasing the number of bases, it is possible to improve the security of this protocol. We also provide the upper bounds on eavesdropping average non-detection probability and propose a control mode modification that increases the attack detection probability.

Zawadzki, Piotr; Miszczak, Jaros?aw Adam

2012-01-01

66

Increasing the security of the ping-pong protocol by using many mutually unbiased bases  

NASA Astrophysics Data System (ADS)

In this paper we propose an extended version of the ping-pong protocol and study its security. The proposed protocol incorporates the usage of mutually unbiased bases in the control mode. We show that, by increasing the number of bases, it is possible to improve the security of this protocol. We also provide the upper bounds on eavesdropping average non-detection probability and propose a control mode modification that increases the attack detection probability.

Zawadzki, Piotr; Pucha?a, Zbigniew; Miszczak, Jaros?aw Adam

2013-01-01

67

Losing the rose tinted glasses: neural substrates of unbiased belief updating in depression  

PubMed Central

Recent evidence suggests that a state of good mental health is associated with biased processing of information that supports a positively skewed view of the future. Depression, on the other hand, is associated with unbiased processing of such information. Here, we use brain imaging in conjunction with a belief update task administered to clinically depressed patients and healthy controls to characterize brain activity that supports unbiased belief updating in clinically depressed individuals. Our results reveal that unbiased belief updating in depression is mediated by strong neural coding of estimation errors in response to both good news (in left inferior frontal gyrus and bilateral superior frontal gyrus) and bad news (in right inferior parietal lobule and right inferior frontal gyrus) regarding the future. In contrast, intact mental health was linked to a relatively attenuated neural coding of bad news about the future. These findings identify a neural substrate mediating the breakdown of biased updating in major depression disorder, which may be essential for mental health. PMID:25221492

Garrett, Neil; Sharot, Tali; Faulkner, Paul; Korn, Christoph W.; Roiser, Jonathan P.; Dolan, Raymond J.

2014-01-01

68

An efficient and unbiased method for sensitivity analysis of stochastic reaction networks.  

PubMed

We consider the problem of estimating parameter sensitivity for Markovian models of reaction networks. Sensitivity values measure the responsiveness of an output with respect to the model parameters. They help in analysing the network, understanding its robustness properties and identifying the important reactions for a specific output. Sensitivity values are commonly estimated using methods that perform finite-difference computations along with Monte Carlo simulations of the reaction dynamics. These methods are computationally efficient and easy to implement, but they produce a biased estimate which can be unreliable for certain applications. Moreover, the size of the bias is generally unknown and hence the accuracy of these methods cannot be easily determined. There also exist unbiased schemes for sensitivity estimation but these schemes can be computationally infeasible, even for very simple networks. Our goal in this paper is to present a new method for sensitivity estimation, which combines the computational efficiency of finite-difference methods with the accuracy of unbiased schemes. Our method is easy to implement and it relies on an exact representation of parameter sensitivity that we recently proved elsewhere. Through examples, we demonstrate that the proposed method can outperform the existing methods, both biased and unbiased, in many situations. PMID:25354975

Gupta, Ankit; Khammash, Mustafa

2014-12-01

69

An Investigation of Nonuniform Deposition of Field Emission Displays Phosphors on Unbiased Indium-Tin-Oxide Coated Glass During Electrophoresis  

NASA Astrophysics Data System (ADS)

Upon the deposition of field emission displays (FED) phosphors in electrophoresis, a weak and nonuniform deposition of phosphor on the unbiased neighbor indium-tin-oxide (ITO) patterns is always observed in addition to the expected thick and uniform deposition of phosphor on the biased patterns. An explanation of the origin of the nonuniform deposition is attempted by solving Laplace’s equation with proper boundary conditions simulating the deposition bath used for the sample preparation. According to the solution of Laplace’s equation, in the beginning, the potential distribution is such that the electric field has a parallel component from the unbiased ITOs to the biased ones in addition to the major vertical components of the electrical field. However, during the deposition, the field has the parallel component from the biased ITOs to the unbiased ones as the thickness of the deposited phosphor increases. This appears to generate the observed nonuniform deposition on the unbiased ITO patterns.

Shin, Sang Hoon; Jeon, Duk Young; Jin, Yong Wan; Kim, Jong Min

2000-12-01

70

Measuring spectra using burst-mode LDA  

NASA Astrophysics Data System (ADS)

The phrase ``burst-mode LDA'' refers to an LDA which operates with at most one particle present in the measuring volume at a time. For the signal to be interpreted correctly to avoid velocity bias, one must apply residence time-weighing to all statistical analysis. In addition, for time-series analysis, even though the randomly arriving particles eliminate aliasing, the self-noise from the random arrivals must be removed or it will dominate the spectra and correlations. A flaw in the earlier theory [1],[2], the goal of which was to provide an unbiased and unaliased spectral estimator from the random samples, is identified and corrected. The new methodology is illustrated using recent experiments in a round jet and a turbulent boundary layer. 1. Buchhave, P. PhD Thesis, SUNY/Buffalo, 1979. 2. George, W.K. Proc. Marseille.-Balt. Dyn. Flow Conf. 1978,757-800.

Velte, Clara; George, William; Tutkun, Murat; Frohnapfel, Bettina

2008-11-01

71

Improving Agricultural Drought Monitoring in East Africa with Unbiased Rainfall Fields and Detailed Land Surface Physics  

NASA Astrophysics Data System (ADS)

Monitoring drought is particularly challenging within rainfed agricultural and pastoral systems, where it can serve the greatest need. Such locations often have sparse or non-existent ground based measurements of precipitation, evapotranspiration (ET), and soil moisture. For more effective drought monitoring with limited hydroclimate observations, we simulate land surface states using the Community Noah Land Surface Model forced with different merged rainfall products inside a Land Information System (LIS). Using model outputs we will answer the questions: How sensitive are soil moisture and ET fields to differences in rainfall forcing and model physics? What are acceptable drought-specific tradeoffs between near-real time availability and skill of rainfall data? Preliminary results with the African Rainfall Estimation Algorithm Version 2 (RFE2.0) outperformed global products, suggesting that sub-global rainfall estimates are the way forward for regional drought monitoring. Specifically, the Noah model forced with RFE2.0 better resolved the heterogeneous patterns in crop stress than the Famine Early Warning System Network (FEWS NET) operational Water Requirement Satisfaction Index (WRSI) model. To further investigate the improvement in drought monitoring while maintaining timeliness, we unbias (using Africa specific climatology) the precipitation products from CPC Merged Analysis of Precipitation (CMAP), Tropical Rainfall Measurement Mission (TRMM), and RFE2.0. The skill (relative accuracy) and reliability (average agreement) of the unbiased rainfall are calculated against an unbiased precipitation product augmented with station data from Ethiopia and Kenya. Soil moisture and ET fields from Noah are compared to the operational FEWS NET WRSI, soil water anomaly index, and the World Food Program’s Crop and Food Security Assessment Mission reports. We anticipate that the unbiased rainfall fields will improve the accuracy, spatio-temporal resolution, and heterogeneity of the ET and soil moisture estimates compared to current operational drought indicators. Ultimately, these improved information products will better inform decision makers about seasonal food production and help them assess the need for relief, potentially saving millions of lives.

McNally, A.; Yatheendradas, S.; Peters-Lidard, C. D.; Michaelsen, J.

2010-12-01

72

Estimating unbiased horizontal velocity components from ST/MST radar measurements: A case study  

NASA Technical Reports Server (NTRS)

In this paper a self-editing quick look procedure is presented for use at the Sunset radar. It is used for determining relatively unbiased hourly estimates of the u and v components of the wind. The technique presented here should be applicable to all height ranges, though only ST results are presented here. The vertical wind component, w, may be measured directly by pointing the radar beam straight up. The east and west components of the wind, u and v, however, must be estimated by projecting to the horizontal plane the radial velocity, vr, actually observed by pointing the radar suitably off zenith.

Clark, W. L.; Green, J. L.; Warnock, J. M.

1983-01-01

73

Unbiased estimation of multi-fractal dimensions of finite data sets  

E-print Network

We present a novel method for determining multi-fractal properties from experimental data. It is based on maximising the likelihood that the given finite data set comes from a particular set of parameters in a multi-parameter family of well known multi-fractals. By comparing characteristic correlations obtained from the original data with those that occur in artificially generated multi-fractals with the {\\em same} number of data points, we expect that predicted multi-fractal properties are unbiased by the finiteness of the experimental data.

A. J. Roberts; A. Cronin

1996-02-01

74

First unbiased spectral survey of a young and single massive protostar: CygX-N63  

NASA Astrophysics Data System (ADS)

We present an unbiased spectral survey of a unique massive protostar in the Cygnus-X region: CygX-N63, performed with the 30m IRAM telescope. We identified 48 molecules over 106 GHz of bandwidth. Two prebiotic molecules were found: CH_2NH (methanimine) and NH_2CHO (formamide) and several rare molecules, such as CF^+ (fluoromethylidynium) or PN (phosphorous nitride). The spectral profiles and the population diagrams of the molecules allowed us to identify three emission regions in the protostar: the envelope, the outflow and a hot core-like region.

Fechtenbaum, S.; Bontemps, S.

2013-11-01

75

Total-moment spectra of fourteen large earthquakes  

NASA Astrophysics Data System (ADS)

Total-moment spectra MT(?) = ?M(?)?/?, where M is the moment rate tensor, are computed for 14 large earthquakes recorded by the International Deployment of Accelerometers (IDA) network using the scalar-moment retrieval method proposed by Silver and Jordan [1982]. For each event we obtain estimates of MT averaged over the 10 disjunct, 1-mHz intervals in the low frequency band 1-11 mHz; typical IDA record sets from events with MT ? 0.2 A (1 A = 1027 dyne · cm) yield standard errors on the 1-mHz averages that are generally less than 20%. Our multiple-band estimates of MT are usually consistent with comparable single-band values found by other investigators. From the total-moment spectra we derive the zero-frequency (static) moment ? ? MT(0) and the characteristic source duration ?c ? 2 (Var [f(t)])½, where f(t) is the time function of the moment rate tensor, assumed to be the same for all components. The parameter ?C formally depends on the second-degree temporal, spatial, and mixed spatial-temporal moments of an extended source, but calculations with realistic source geometries indicate that the interpretation of TC strictly in terms of the second temporal moment leads to very little error. A plot of ?c against ? shows considerable scatter; some events lie significantly above the empirical scaling curve of Kanamori and Given [1981] (`slow earthquakes') and some below (`fast earthquakes'). Examples of the former include all three deep-focus events analyzed here as well as the 1970 Colombia and 1963 Peru-Bolivia deep-focus earthquakes, whose total-moment spectra are calculated from the moment tensor solutions of Gilbert and Dziewonski [1975]. An example of the latter is the great Sumbawa earthquake of August 9, 1977 (? = 24±3 A), which is inferred to have a relatively shallow spatial centroid (< 20 km) and a nearly flat moment spectrum, suggesting that the faulting was confined to the upper, more brittle portion of the oceanic lithosphere. Three other large earthquakes—Tonga (June 22, 1977; ? = 23±2 A), Kuril Islands (December 6, 1978; ? = 3.6±0.2 A), and Tumaco (December 12, 1979; ? = 25±2 A)—exhibit moment spectra which significantly decrease toward higher frequencies, indicating larger values of ?c. The aftershocks of both the Tonga and Kuril Islands events are distributed over a considerable range of depths, consistent with rupture into the lower, more ductile portions of the oceanic lithosphere. We speculate that the characteristic source duration may be causally related to the depth of coseismic rupturing within the lithosphere.

Silver, Paul G.; Jordan, Thomas H.

1983-04-01

76

Far-infrared observations of an unbiased sample of gamma-ray burst host galaxies  

E-print Network

Gamma-ray bursts (GRBs) are the most energetic phenomena in the Universe; believed to result from the collapse and subsequent explosion of massive stars. Even though it has profound consequences for our understanding of their nature and selection biases, little is known about the dust properties of the galaxies hosting GRBs. We present analysis of the far-infrared properties of an unbiased sample of 21 GRB host galaxies (at an average redshift of $z\\,=\\,3.1$) located in the {\\it Herschel} Astrophysical Terahertz Large Area Survey (H-ATLAS), the {\\it Herschel} Virgo Cluster Survey (HeViCS), the {\\it Herschel} Fornax Cluster Survey (HeFoCS), the {\\it Herschel} Stripe 82 Survey (HerS) and the {\\it Herschel} Multi-tiered Extragalactic Survey (HerMES), totalling $880$ deg$^2$, or $\\sim 3$\\% of the sky in total. Our sample selection is serendipitous, based only on whether the X-ray position of a GRB lies within a large-scale {\\it Herschel} survey -- therefore our sample can be considered completely unbiased. Using ...

Kohn, Saul A; Bourne, Nathan; Baes, Maarten; Fritz, Jacopo; Cooray, Asantha; De Looze, Ilse; De Zotti, Gianfranco; Dannerbauer, Helmut; Dunne, Loretta; Dye, Simon; Eales, Stephen; Furlanetto, Cristina; Gonzalez-Nuevo, Joaquin; Ibar, Edo; Ivison, Rob J; Maddox, Steve J; Scott, Douglas; Smith, Daniel J B; Smith, Matthew W L; Symeonidis, Myrto; Valiante, Elisabetta

2015-01-01

77

Weighted skewness and kurtosis unbiased by sample size and Gaussian uncertainties  

NASA Astrophysics Data System (ADS)

Central moments and cumulants are often employed to characterize the distribution of data. The skewness and kurtosis are particularly useful for the detection of outliers, the assessment of departures from normally distributed data, automated classification techniques and other applications. Estimators of higher order moments that are robust against outliers are more stable but might miss characteristic features of the data, as in the case of astronomical time series exhibiting brief events like stellar bursts or eclipses of binary systems, while weighting can help identify reliable measurements from uncertain or spurious outliers. Furthermore, noise is an unavoidable part of most measurements and their uncertainties need to be taken properly into account during the data analysis or biases are likely to emerge in the results, including basic descriptive statistics. This work provides unbiased estimates of the weighted skewness and kurtosis moments and cumulants, corrected for biases due to sample size and Gaussian noise, under the assumption of independent data. A comparison of biased and unbiased weighted estimators is illustrated with simulations as a function of sample size and signal-to-noise ratio, employing different data distributions and weighting schemes related to measurement uncertainties and the sampling of the signal. Detailed derivations and figures of simulation results are presented in the Appendices available online.

Rimoldini, Lorenzo

2014-07-01

78

Independent unbiased coin flips from a correlated biased source—A finite state markov chain  

Microsoft Academic Search

Von Neumann’s trick for simulating anabsolutely unbiased coin by a biased one is this:\\u000a \\u000a \\u000a 1. \\u000a \\u000a Toss the biased coin twice, getting 00, 01, 10, or 11.\\u000a \\u000a \\u000a \\u000a \\u000a 2. \\u000a \\u000a If 00 or 11 occur, go back to step 1; else\\u000a \\u000a \\u000a \\u000a \\u000a 3. \\u000a \\u000a Call 10 aH, 01 aT.\\u000a \\u000a \\u000a \\u000a \\u000a \\u000a \\u000a Since Pr[H]=Pr[1]Pr[0]=Pr[T], the output is unbiased. Example: 00 10 11 01 01 ?HTT.\\u000a \\u000a \\u000a \\u000a Peter Elias gives

Manuel Blum

1986-01-01

79

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

80

An Unbiased Method for Clustering Bacterial Effectors Using Host Cellular Phenotypes  

PubMed Central

We present a novel method implementing unbiased high-content morphometric cell analysis to classify bacterial effector phenotypes. This clustering methodology represents a significant advance over more qualitative visual approaches and can also be used to classify, and therefore predict the likely function of, unknown effector genes from any microbial genome. As a proof of concept, we use this approach to investigate 23 genetic regions predicted to encode antimacrophage effectors located across the genome of the insect and human pathogen Photorhabdus asymbiotica. Statistical cluster analysis using multiple cellular measures categorized treated macrophage phenotypes into three major groups relating to their putative functionality: (i) adhesins, (ii) cytolethal toxins, and (iii) cytomodulating toxins. Further investigation into their effects on phagocytosis revealed that several effectors also modulate this function and that the nature of this modulation (increased or decreased phagocytosis) is linked to the phenotype cluster group. Categorizing potential functionalities in this way allows rapid functional follow-up of key candidates for more-directed cell biological or biochemical investigation. Such an unbiased approach to the classification of candidate effectors will be useful for describing virulence-related regions in a wide range of genomes and will be useful in assigning putative functions to the growing number of microbial genes whose function remains unclear from homology searching. PMID:24296505

Hodgson, David J.

2014-01-01

81

Galaxy and Stellar Spectra  

NSDL National Science Digital Library

In this activity students learn that galaxies shine on the basis of their intergrated stellar population, therefore, adding together different stellar spectra should reproduce the spectra of a galaxy. This activity contains an applet which allows one to add spectra of up to four different stars to produce a resultant spectra. To reproduce qualitatively a spectra of a galaxy one can add together and F main sequence star and a K Giant. The spectra are normalized by V-band luminosity.

Department, University O.

2005-06-17

82

FALCON: fast and unbiased reconstruction of high-density super-resolution microscopy data  

PubMed Central

Super resolution microscopy such as STORM and (F)PALM is now a well known method for biological studies at the nanometer scale. However, conventional imaging schemes based on sparse activation of photo-switchable fluorescent probes have inherently slow temporal resolution which is a serious limitation when investigating live-cell dynamics. Here, we present an algorithm for high-density super-resolution microscopy which combines a sparsity-promoting formulation with a Taylor series approximation of the PSF. Our algorithm is designed to provide unbiased localization on continuous space and high recall rates for high-density imaging, and to have orders-of-magnitude shorter run times compared to previous high-density algorithms. We validated our algorithm on both simulated and experimental data, and demonstrated live-cell imaging with temporal resolution of 2.5 seconds by recovering fast ER dynamics. PMID:24694686

Min, Junhong; Vonesch, Cédric; Kirshner, Hagai; Carlini, Lina; Olivier, Nicolas; Holden, Seamus; Manley, Suliana; Ye, Jong Chul; Unser, Michael

2014-01-01

83

Unbiased reduced density matrices and electronic properties from full configuration interaction quantum Monte Carlo.  

PubMed

Properties that are necessarily formulated within pure (symmetric) expectation values are difficult to calculate for projector quantum Monte Carlo approaches, but are critical in order to compute many of the important observable properties of electronic systems. Here, we investigate an approach for the sampling of unbiased reduced density matrices within the full configuration interaction quantum Monte Carlo dynamic, which requires only small computational overheads. This is achieved via an independent replica population of walkers in the dynamic, sampled alongside the original population. The resulting reduced density matrices are free from systematic error (beyond those present via constraints on the dynamic itself) and can be used to compute a variety of expectation values and properties, with rapid convergence to an exact limit. A quasi-variational energy estimate derived from these density matrices is proposed as an accurate alternative to the projected estimator for multiconfigurational wavefunctions, while its variational property could potentially lend itself to accurate extrapolation approaches in larger systems. PMID:25554143

Overy, Catherine; Booth, George H; Blunt, N S; Shepherd, James J; Cleland, Deidre; Alavi, Ali

2014-12-28

84

Denoising PET Images Using Singular Value Thresholding and Stein's Unbiased Risk Estimate*  

PubMed Central

Image denoising is an important pre-processing step for accurately quantifying functional morphology and measuring activities of the tissues using PET images. Unlike structural imaging modalities, PET images have two difficulties: (1) the Gaussian noise model does not necessarily fit into PET imaging because the exact nature of noise propagation in PET imaging is not well known, and (2) PET images are low resolution; therefore, it is challenging to denoise them while preserving structural information. To address these two difficulties, we introduce a novel methodology for denoising PET images. The proposed method uses the singular value thresholding concept and Stein's unbiased risk estimate to optimize a soft thresholding rule. Results, obtained from 40 MRI-PET images, demonstrate that the proposed algorithm is able to denoise PET images successfully, while still maintaining the quantitative information. PMID:24505751

Bagci, Ulas; Mollura, Daniel J.

2014-01-01

85

Unbiased classification of sensory neuron types by large-scale single-cell RNA sequencing.  

PubMed

The primary sensory system requires the integrated function of multiple cell types, although its full complexity remains unclear. We used comprehensive transcriptome analysis of 622 single mouse neurons to classify them in an unbiased manner, independent of any a priori knowledge of sensory subtypes. Our results reveal eleven types: three distinct low-threshold mechanoreceptive neurons, two proprioceptive, and six principal types of thermosensitive, itch sensitive, type C low-threshold mechanosensitive and nociceptive neurons with markedly different molecular and operational properties. Confirming previously anticipated major neuronal types, our results also classify and provide markers for new, functionally distinct subtypes. For example, our results suggest that itching during inflammatory skin diseases such as atopic dermatitis is linked to a distinct itch-generating type. We demonstrate single-cell RNA-seq as an effective strategy for dissecting sensory responsive cells into distinct neuronal types. The resulting catalog illustrates the diversity of sensory types and the cellular complexity underlying somatic sensation. PMID:25420068

Usoskin, Dmitry; Furlan, Alessandro; Islam, Saiful; Abdo, Hind; Lönnerberg, Peter; Lou, Daohua; Hjerling-Leffler, Jens; Haeggström, Jesper; Kharchenko, Olga; Kharchenko, Peter V; Linnarsson, Sten; Ernfors, Patrik

2015-01-01

86

An unbiased X-ray sampling of stars within 25 parsecs of the Sun  

NASA Technical Reports Server (NTRS)

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.

1985-01-01

87

Size Unbiased Representative Enzymatically Generated RNAi (SURER) Library and Application for RNAi Therapeutic Screens.  

PubMed

RNA interference (RNAi) libraries screens have become widely used for small RNA (sRNA) therapeutic targets development. However, conventional enzymatically libraries, typically prepared using the type 2 restriction enzyme MmeI, produce sRNAs between 18 and 20?bp, much shorter than the usual lengths of 19-23?bp. Here we develop a size unbiased representative enzymatically generated RNAi (SURER) library, which employs type 3 restriction modification enzyme EcoP15I to produce sRNAs ranging from 19 to 23?bp using a group of rationally designed linkers, which can completely mimic the length of sRNAs naturally generated by Dicer enzyme in living cells, and the screening results of SURER libraries showed high recombination rate and knockdown efficiency. SURER library provides a useful tool for RNAi therapeutics screening in a fast and simple way. PMID:25493330

Li, Tiejun; Zhu, York Yuanyuan; Chen, Li; Sun, Yuncheng; Yuan, Jian; Graham, Michael; French, Peter

2015-02-01

88

Unbiased reduced density matrices and electronic properties from full configuration interaction quantum Monte Carlo  

NASA Astrophysics Data System (ADS)

Properties that are necessarily formulated within pure (symmetric) expectation values are difficult to calculate for projector quantum Monte Carlo approaches, but are critical in order to compute many of the important observable properties of electronic systems. Here, we investigate an approach for the sampling of unbiased reduced density matrices within the full configuration interaction quantum Monte Carlo dynamic, which requires only small computational overheads. This is achieved via an independent replica population of walkers in the dynamic, sampled alongside the original population. The resulting reduced density matrices are free from systematic error (beyond those present via constraints on the dynamic itself) and can be used to compute a variety of expectation values and properties, with rapid convergence to an exact limit. A quasi-variational energy estimate derived from these density matrices is proposed as an accurate alternative to the projected estimator for multiconfigurational wavefunctions, while its variational property could potentially lend itself to accurate extrapolation approaches in larger systems.

Overy, Catherine; Booth, George H.; Blunt, N. S.; Shepherd, James J.; Cleland, Deidre; Alavi, Ali

2014-12-01

89

Quantitative unbiased estimates of endometrial gland surface area and volume in cycling cows and heifers.  

PubMed

Entire reproductive tracts were removed from seven normal healthy heifers and qualitative unbiased estimates made of endometrial gland volume density and glandular surface density. After examining approximately 55 microscopic fields of endometrium from each tract, a mean glandular surface density value of 10.2 mm(2)/mm(3) (CE 3.1%) was obtained. The stereological method was then employed in optimising the design of the main study. The endometrial height was measured for 17 healthy cycling heifers and 19 similar cows. Subsequently, unbiased estimates were made of intercaruncular endometrial gland volume per unit surface for all cattle were investigated; differences between heifers and cows generally, and the possible effect of the follicular and luteal phases of the oestrous cycle were compared. The mean surface area of glands per unit area of endometrium at the intercaruncular site in heifers and cows was approximately 18 mm(2)/mm(2) in the follicular phase and 26 mm(2)/mm(2) in the luteal phase, figures similar to the gland area found in women. The intercaruncular gland volume increased significantly, by about 30% during the luteal phase of the bovine oestrous cycle in heifers, from 0.01 to 0.13 per mm(3). The differences in endometrial anatomy between site of sampling and either follicular or luteal phases of the oestrous cycle were always more significant in heifers than cows. The endometrial thickness in cows was always greater than for heifers, irrespective of the site of sampling. It was concluded that the intercaruncular endometrium of cattle was far more active physiologically than recognised previously. PMID:12443683

Dhaliwal, G S; Murray, R D; Rees, E M; Howard, C V; Beech, D J

2002-12-01

90

Off-Axis Electron Holography of Unbiased and Reverse-Biased Focused Ion Beam Milled Si p-n Junctions  

E-print Network

Off-Axis Electron Holography of Unbiased and Reverse-Biased Focused Ion Beam Milled Si p, Cambridge CB2 3QZ, UK Abstract: Off-axis electron holography is used to measure electrostatic potential and the electrostatic potential in the thin sample. Key words: off-axis electron holography, p-n junction, reverse bias

Dunin-Borkowski, Rafal E.

91

Unravelling the matrix effect of fresh sampled cells for in vivo unbiased FTIR determination of the absolute concentration of total lipid content of microalgae.  

PubMed

Over the past years, the substitution of the classical biochemical quantification techniques by Fourier transform infrared (FTIR) spectroscopy has been widely studied on microalgae because of its tremendous application potential for bioprocess monitoring. In the present work, mandatory aspects that have never been approached by FTIR end-users working onto fresh biomass were assessed. We demonstrated first that fresh cells' FTIR spectra main characteristics could be severely and unspecifically altered when the properties of the sampled biomass were not monitored. Microscopy indicated that important cell reorganization could occur when diminishing the cells density of the sample. Molecular probing approach suggested that such a modification could provoke an alteration of the hydrogen-bonding network of the sample. The sample heterogeneity was found to impact also the shape and intensity of the recorded FTIR bands, participating then to a matrix effect uncharacterized until now. In the second part of our study, we selected FTIR spectra not influenced by this matrix effect and the corresponding accurate calibration data obtained by the whole cell analytical procedure to elaborate an optimized total lipid quantification PLS-R model. Results demonstrated that our strategy could provide a small volume sampling (1 mL of fresh culture), rapid (within minutes), robust (physiological condition independent), and accurate (as accurate as the reference method could be) FTIR absolute quantification method to determine the fresh microalgae intracellular total lipid content. To validate our unbiased FTIR approach, a photobioprocess monitoring pipeline was developed and allowed assessing the effect of light attenuation on total lipid production by the marine microalga Nannochloropsis oculata. PMID:24788985

Coat, Rémy; Montalescot, Valeria; León, Esteban Serrano; Kucma, Delphine; Perrier, Candice; Jubeau, Sébastien; Thouand, Gérald; Legrand, Jack; Pruvost, Jérémy; Gonçalves, Olivier

2014-11-01

92

Unresolved mossbauer hyperfine spectra  

NASA Technical Reports Server (NTRS)

Program analyzes unresolved Mossbauer hyperfine spectra resulting from existence of several local environments in dilute binary iron alloys. It has proven useful in studying effects of imputity atoms on iron Mossbauer spectra.

Schiess, J. R.; Singh, J. J.

1980-01-01

93

Statistical Properties of Maximum Likelihood Estimators of Power Law Spectra Information  

NASA Technical Reports Server (NTRS)

A simple power law model consisting of a single spectral index, sigma(sub 2), is believed to be an adequate description of the galactic cosmic-ray (GCR) proton flux at energies below 10(exp 13) eV, with a transition at the knee energy, E(sub k), to a steeper spectral index sigma(sub 2) greater than sigma(sub 1) above E(sub k). The maximum likelihood (ML) procedure was developed for estimating the single parameter sigma(sub 1) of a simple power law energy spectrum and generalized to estimate the three spectral parameters of the broken power law energy spectrum from simulated detector responses and real cosmic-ray data. The statistical properties of the ML estimator were investigated and shown to have the three desirable properties: (Pl) consistency (asymptotically unbiased), (P2) efficiency (asymptotically attains the Cramer-Rao minimum variance bound), and (P3) asymptotically normally distributed, under a wide range of potential detector response functions. Attainment of these properties necessarily implies that the ML estimation procedure provides the best unbiased estimator possible. While simulation studies can easily determine if a given estimation procedure provides an unbiased estimate of the spectra information, and whether or not the estimator is approximately normally distributed, attainment of the Cramer-Rao bound (CRB) can only be ascertained by calculating the CRB for an assumed energy spectrum- detector response function combination, which can be quite formidable in practice. However, the effort in calculating the CRB is very worthwhile because it provides the necessary means to compare the efficiency of competing estimation techniques and, furthermore, provides a stopping rule in the search for the best unbiased estimator. Consequently, the CRB for both the simple and broken power law energy spectra are derived herein and the conditions under which they are stained in practice are investigated.

Howell, L. W., Jr.

2003-01-01

94

Obtaining an unbiased estimate of intake in routine monitoring when the time of intake is unknown.  

PubMed

A common problem in internal dosimetry occurs in routine monitoring, when it is required to estimate an intake from a measurement made at the end of a monitoring interval, and the time of intake is unknown. ICRP suggests that, in these cases, it should be assumed that the intake occurred in the middle of the monitoring period. However, it has been shown that this will, in the long term, lead to biased estimates of a worker's intake and dose. In order to overcome this biasing, the United States Department of Energy (USDOE) recommends a different method based on calculating the intakes for all possible intake-times in the interval, and then taking an arithmetic average. In this paper, it is shown that both the ICRP and USDOE methods are biased. An alternative method is suggested, which assumes a constant chronic intake throughout the monitoring interval. Monte Carlo simulations are used to estimate the magnitude of bias for two realistic monitoring programmes using all three methods. It is shown that the proposed method is unbiased and also yields estimates of intake that are generally closer to the actual intake, than the other two. The Monte Carlo conclusions are backed up by a theoretical analysis of bias. Finally, the source of bias in the apparently intuitive approach of the USDOE method is revealed by viewing the problem from a Bayesian perspective. PMID:16410294

Puncher, M; Marsh, J W; Birchall, A

2006-01-01

95

An anatomically unbiased foot template for inter-subject plantar pressure evaluation.  

PubMed

Pedobarographic images reflect the dynamic interaction between the plantar foot and supporting surfaces during gait and postural activities. Since intra-foot and inter-subject contact geometry are grossly similar, images may be spatially registered and directly compared. Previously arbitrary subjects have been selected as registration templates, but this can conceivably introduce anatomical bias. The purposes of this study were: (i) to compute an unbiased pedobarographic template from a large sample of healthy young adult subjects, and (ii) to demonstrate how the resulting template may be used for practical clinical and scientific analyses. Images were obtained from N=104 subjects and were registered (10,712 pairs) using (i) an optimal linear scaling technique and (ii) a nonlinear, locally affine, globally smooth technique. The nonlinear technique was found to offer biomechanically non-trivial advantages over the linear technique, most likely due to non-proportional inter-subject geometry. Specifically, the nonlinear template was able to detect morphological signals in a hallux valgus sample with greater sensitivity than the linear template. Validity of the approach was confirmed by independently assessing left and right feet, through a statistical comparison of local maximal pressures, and also through examination of random subject subsets. The current template, representative of an average healthy foot, could be a valuable resource for automated clinical and scientific analyses of foot morphology and function. PMID:21227692

Pataky, Todd C; Bosch, Kerstin; Mu, Tingting; Keijsers, Noël L W; Segers, Veerle; Rosenbaum, Dieter; Goulermas, John Y

2011-03-01

96

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. PMID:20734316

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

2010-01-01

97

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

PubMed Central

SUMMARY 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 novel receptor for LRRTM4 using an unbiased proteomics-based approach. Glypican binds LRRTM4, but not LRRTM2, in a 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 a 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 a novel 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

2014-01-01

98

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. PMID:20839807

Julian, Lisa D.; Hartwig, John F.

2010-01-01

99

TOWARD UNBIASED GALAXY CLUSTER MASSES FROM LINE-OF-SIGHT VELOCITY DISPERSIONS  

SciTech Connect

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 {approx}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 [Department of Physics, Ludwig-Maximilians-Universitaet, Scheinerstr. 1, D-81679 Muenchen (Germany)

2013-07-20

100

Automatic sampling for unbiased and efficient stereological estimation using the proportionator in biological studies.  

PubMed

Quantification of tissue properties is improved using the general proportionator sampling and estimation procedure: automatic image analysis and non-uniform sampling with probability proportional to size (PPS). The complete region of interest is partitioned into fields of view, and every field of view is given a weight (the size) proportional to the total amount of requested image analysis features in it. The fields of view sampled with known probabilities proportional to individual weight are the only ones seen by the observer who provides the correct count. Even though the image analysis and feature detection is clearly biased, the estimator is strictly unbiased. The proportionator is compared to the commonly applied sampling technique (systematic uniform random sampling in 2D space or so-called meander sampling) using three biological examples: estimating total number of granule cells in rat cerebellum, total number of orexin positive neurons in transgenic mice brain, and estimating the absolute area and the areal fraction of beta islet cells in dog pancreas. The proportionator was at least eight times more efficient (precision and time combined) than traditional computer controlled sampling. PMID:18387046

Gardi, J E; Nyengaard, J R; Gundersen, H J G

2008-04-01

101

Absorption and folding of melittin onto lipid bilayer membranes via unbiased atomic detail microsecond molecular dynamics simulation.  

PubMed

Unbiased molecular simulation is a powerful tool to study the atomic details driving functional structural changes or folding pathways of highly fluid systems, which present great challenges experimentally. Here we apply unbiased long-timescale molecular dynamics simulation to study the ab initio folding and partitioning of melittin, a template amphiphilic membrane active peptide. The simulations reveal that the peptide binds strongly to the lipid bilayer in an unstructured configuration. Interfacial folding results in a localized bilayer deformation. Akin to purely hydrophobic transmembrane segments the surface bound native helical conformer is highly resistant against thermal denaturation. Circular dichroism spectroscopy experiments confirm the strong binding and thermostability of the peptide. The study highlights the utility of molecular dynamics simulations for studying transient mechanisms in fluid lipid bilayer systems. This article is part of a Special Issue entitled: Interfacially Active Peptides and Proteins. Guest Editors: William C. Wimley and Kalina Hristova. PMID:24769159

Chen, Charles H; Wiedman, Gregory; Khan, Ayesha; Ulmschneider, Martin B

2014-09-01

102

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

103

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. PMID:23103185

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

2013-01-01

104

Unbiased Correction Relations for Galaxy Cluster Properties Derived from Chandra and XMM-Newton  

NASA Astrophysics Data System (ADS)

We use a sample of 62 clusters of galaxies to investigate the discrepancies between the gas temperature and total mass within r 500 from XMM-Newton and Chandra data. Comparisons of the properties show that (1) both the de-projected and projected temperatures determined by Chandra are higher than those of XMM-Newton and there is a good linear relationship for the de-projected temperatures: T Chandra = 1.25 × T XMM–0.13. (2) The Chandra mass is much higher than the XMM-Newton mass with a bias of 0.15 and our mass relation is log10 M Chandra = 1.02 × log10 M XMM+0.15. To explore the reasons for the discrepancy in mass, we recalculate the Chandra mass (expressed as M_Ch^mo/d) by modifying its temperature with the de-projected temperature relation. The results show that M_Ch^mo/d is closer to the XMM-Newton mass with the bias reducing to 0.02. Moreover, M_Ch^mo/d are corrected with the r 500 measured by XMM-Newton and the intrinsic scatter is significantly improved with the value reducing from 0.20 to 0.12. These mean that the temperature bias may be the main factor causing the mass bias. Finally, we find that M_Ch^mo/d is consistent with the corresponding XMM-Newton mass derived directly from our mass relation at a given Chandra mass. Thus, the de-projected temperature and mass relations can provide unbiased corrections for galaxy cluster properties derived from Chandra and XMM-Newton.

Zhao, Hai-Hui; Li, Cheng-Kui; Chen, Yong; Jia, Shu-Mei; Song, Li-Ming

2015-01-01

105

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. PMID:20090945

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

2010-01-01

106

Superfast fronts of impact ionization in initially unbiased layered semiconductor structures  

NASA Astrophysics Data System (ADS)

A mode of impact ionization breakdown of a p-n junction is suggested: We demonstrate that when a sufficiently sharp voltage ramp is applied in reverse direction to an initially unbiased equilibrium p+-n-n+ structure, after some delay the system will reach a high conductivity state via the propagation of a superfast impact ionization front. The front travels towards the anode with a velocity vf several times larger than the saturated drift velocity of electrons vs leaving a dense electron-hole plasma behind. The excitation of the superfast front corresponds to the transition from the common avalanche breakdown of a semiconductor structure to a collective mode of streamer-like breakdown. We propose that similar fronts can be excited not in layered structures but in plain bulk samples without p-n junctions. Our numerical simulations apply to a Si structure with typical thickness of Wapprox100 mum switched in series with a load Rapprox100 Omega, with a voltage ramp of A>1012 V/s applied to the whole system. Our simulations show that first there is a delay of about 1 ns during which the voltage reaches a value of several kilovolts. Then, as the front is triggered, the voltage abruptly breaks down to several hundreds of volts within approx100 ps. This provides a voltage ramp of up to approx2 x1013 V/s hence up to 10 times sharper than the externally applied ramp. We unravel the source of initial carriers which trigger the front, explain the origin of the time delay in triggering the front, and we identify the mechanism of front propagation.

Rodin, P.; Ebert, U.; Hundsdorfer, W.; Grekhov, I. V.

2002-08-01

107

Unbiased estimation of chloroplast number in mesophyll cells: advantage of a genuine three-dimensional approach  

PubMed Central

Chloroplast number per cell is a frequently examined quantitative anatomical parameter, often estimated by counting chloroplast profiles in two-dimensional (2D) sections of mesophyll cells. However, a mesophyll cell is a three-dimensional (3D) structure and this has to be taken into account when quantifying its internal structure. We compared 2D and 3D approaches to chloroplast counting from different points of view: (i) in practical measurements of mesophyll cells of Norway spruce needles, (ii) in a 3D model of a mesophyll cell with chloroplasts, and (iii) using a theoretical analysis. We applied, for the first time, the stereological method of an optical disector based on counting chloroplasts in stacks of spruce needle optical cross-sections acquired by confocal laser-scanning microscopy. This estimate was compared with counting chloroplast profiles in 2D sections from the same stacks of sections. Comparing practical measurements of mesophyll cells, calculations performed in a 3D model of a cell with chloroplasts as well as a theoretical analysis showed that the 2D approach yielded biased results, while the underestimation could be up to 10-fold. We proved that the frequently used method for counting chloroplasts in a mesophyll cell by counting their profiles in 2D sections did not give correct results. We concluded that the present disector method can be efficiently used for unbiased estimation of chloroplast number per mesophyll cell. This should be the method of choice, especially in coniferous needles and leaves with mesophyll cells with lignified cell walls where maceration methods are difficult or impossible to use. PMID:24336344

Kubínová, Zuzana

2014-01-01

108

A novel unbiased counting method for the quantification of synapses in the mouse brain  

PubMed Central

Background The numerical density of synapses and their ultrastructural features are best assessed with electron microscopy. Counting is done within counting frames placed on a pair of sections (disector technique). But this requires that the thin sections are taken from comparable brain regions and the disectors are placed in a uniform random fashion. Small brain areas like the polymorph layer of the mouse dentate gyrus are difficult to encounter, and manually moving the microscope stage for placing the micrographs seems arbitrary. New method Here the polymorph layer was approximated with 20 ?m thin, Nissl-stained vibratome sections. The subsequent vibratome section was processed for electron microscopy and serially thin sectioned. The microscope stage was moved using a random number generator, placing at least 20 disectors onto a pair of sections. The numerical synapse density, the numerical density of dense-core vesicles, and other ultrastructural features were compared between mice that had been kept in an enriched environment and mice kept under standard housing conditions. Results Environmental enrichment significantly decreased the numerical density of dense-core vesicles and synaptic cleft widths within the polymorph layer, associated with behavioral improvement in the Morris water maze, a hippocampus-dependent task of spatial learning and memory. Comparison with existing methods This procedure was easy to handle and enabled us to produce thin sections in small, defined brain areas. Furthermore, placing the disectors with random numbers excluded observer bias. Conclusions Our procedure provides an uncomplicated way of assessing numerical densities in small brain areas in an unbiased manner. PMID:25445248

Reichmann, Florian; Painsipp, Evelin; Holzer, Peter; Kummer, Daniel; Bock, Elisabeth; Leitinger, Gerd

2015-01-01

109

An unbiased survey for CO emission in the inner disk of the Andromeda galaxy.  

NASA Astrophysics Data System (ADS)

Recently, Allen & Lequeux (???) have detected faint CO emission from two massive molecular clouds in the inner disk of M 31. These clouds were first located optically by their dust content. In order to determine the validity of this selection criterion, we have carried out an "unbiased" survey at 26 positions regularly spaced every 3.6' along the major axis of M 31. Faint CO emission was detected for 16 of them. Dark clouds are seen optically at many of the positions where CO is detected, confirming a posteriori the proposition that there is a close correlation between the presence of dust and the presence of faint CO emission. However, we also find detectable CO emission at positions for which there are no catalogued dust clouds; the survey therefore points to a significantly larger area covering factor for the molecular gas in the inner disk of M 31 than previously thought. Our observations suggest that the mass surface density of gas perpendicular to the plane of the disk is as high as 10xMsun_pc^-2^ in the inner regions of M 31, which exhibits no central "gas hole" contrary to the common belief. The velocities of the CO(1-0) lines trace a rotation curve which is in general agreement with that of the HI obtained earlier by Brinks & Shane (???), although the component of the HI attributed by those authors to a warp of the outer disk of M 31 seen in projection on the inner disk does not appear to have a counterpart in CO at the present level of detection. The ratios of the integrated CO(2-1) to CO(1-0) line intensities, when both can be measured, are generally very low (~0.4), consistent with models of cold (T_K_<5K) molecular clouds at low density (~100cm^-3^).

Loinard, L.; Allen, R. J.; Lequeux, J.

1995-09-01

110

Unbiased Estimate of Dark Energy Density from Type Ia Supernova Data  

E-print Network

Type Ia supernovae (SNe Ia) are currently the best probes of the dark energy in the universe. To constrain the nature of dark energy in a model-independent manner, we allow the density of dark energy, $\\rho_X(z)$, to be an arbitrary function of redshift. Using simulated data from a space-based supernova pencil beam survey, we find that by optimizing the number of parameters used to parametrize the dimensionless dark energy density, $f(z)=\\rho_X(z)/\\rho_X(z=0)$, we can obtain an unbiased estimate of both f(z) and $\\Omega_m$ (assuming a flat universe and that the weak energy condition is satisfied). A plausible supernova pencil beam survey (with a square degree field of view and for an observational duration of one year) can yield about 2000 SNe Ia with $0\\le z \\le 2$. Such a survey in space would yield SN peak luminosities with a combined intrinsic and observational dispersion of $\\sigma (m_{int})=0.16$ mag. We find that for such an idealized survey, $\\Omega_m$ can be measured to 10% accuracy, and f(z) can be estimated to $\\sim$ 20% to $z \\sim 1.5$, and $\\sim$ 20-40% to $z \\sim 2$, depending on the time dependence of the true dark energy density. Dark energy densities which vary more slowly can be more accurately measured. For the anticipated SNAP mission, $\\Omega_m$ can be measured to 14% accuracy, and f(z) can be estimated to $\\sim$ 20% to $z \\sim 1.2$. Our results suggest that SNAP may gain much sensitivity to the time-dependence of f(z) and $\\Omega_m$ by devoting more observational time to the central pencil beam fields to obtain more SNe Ia at z>1.2. We also find that Monte Carlo analysis gives a more accurate estimate of the dark energy density than the maximum likelihood analysis. (abridged)

Yun Wang; Geoffrey Lovelace

2001-09-17

111

Unbiased and non-supervised learning methods for disruption prediction at JET  

NASA Astrophysics Data System (ADS)

The importance of predicting the occurrence of disruptions is going to increase significantly in the next generation of tokamak devices. The expected energy content of ITER plasmas, for example, is such that disruptions could have a significant detrimental impact on various parts of the device, ranging from erosion of plasma facing components to structural damage. Early detection of disruptions is therefore needed with evermore increasing urgency. In this paper, the results of a series of methods to predict disruptions at JET are reported. The main objective of the investigation consists of trying to determine how early before a disruption it is possible to perform acceptable predictions on the basis of the raw data, keeping to a minimum the number of 'ad hoc' hypotheses. Therefore, the chosen learning techniques have the common characteristic of requiring a minimum number of assumptions. Classification and Regression Trees (CART) is a supervised but, on the other hand, a completely unbiased and nonlinear method, since it simply constructs the best classification tree by working directly on the input data. A series of unsupervised techniques, mainly K-means and hierarchical, have also been tested, to investigate to what extent they can autonomously distinguish between disruptive and non-disruptive groups of discharges. All these independent methods indicate that, in general, prediction with a success rate above 80% can be achieved not earlier than 180 ms before the disruption. The agreement between various completely independent methods increases the confidence in the results, which are also confirmed by a visual inspection of the data performed with pseudo Grand Tour algorithms.

Murari, A.; Vega, J.; Rattá, G. A.; Vagliasindi, G.; Johnson, M. F.; Hong, S. H.; JET-EFDA Contributors

2009-05-01

112

An Unbiased Approach to Identifying Tau Kinases That Phosphorylate Tau at Sites Associated with Alzheimer Disease  

PubMed Central

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

2013-01-01

113

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. 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.

2012-01-01

114

Unbiased estimates of long-term net survival of solid cancers in France.  

PubMed

In cancer studies, net survival (observed if cancer was the only cause of death) is a useful indicator but survival estimation at 5 years is insufficient for planning healthcare needs. We estimated the net survivals at 5 and 10 years in a cohort of 387,961 patients who had solid tumors between 1989 and 2004 and were followed-up until January 1, 2008. The cases were actively followed-up. Net survival was estimated with the unbiased Pohar-Perme method. The standardized net survival used the international cancer survival standard weights. In men, the standardized net survivals ranged from 92% at 5 years and 89% at 10 years (testis) to 6% at 5 years and 5% at 10 years (pancreas). In women, it ranged from 91% at 5 years and 88% at 10 years (thyroid) to 10% at 5 years and 7% at 10 years (pancreas). The most frequent cancers had the highest net survivals: 84% at 5 years and 71% at 10 years for prostate and 84% at 5 years and 74% at 10 years for breast cancer. Advanced age was associated with poorer prognosis. In most cancers, the net survivals at 5 and 10 years increased over periods of diagnosis. Net cancer survival is unaffected by mortalities due to other causes. It is the only indicator suitable for comparisons between countries or periods of diagnosis within a given country. The 10-year net survival confirmed the persistent unfavorable role of age in prognosis and the general improvement of cancer management over the last decade. PMID:23001495

Jooste, Valérie; Grosclaude, Pascale; Remontet, Laurent; Launoy, Guy; Baldi, Isabelle; Molinié, Florence; Arveux, Patrick; Bossard, Nadine; Bouvier, Anne-Marie; Colonna, Marc

2013-05-15

115

A practical methodology to measure unbiased gas chromatographic retention factor vs. temperature relationships.  

PubMed

Compound identification continues to be a major challenge. Gas chromatography-mass spectrometry (GC-MS) is a primary tool used for this purpose, but the GC retention information it provides is underutilized because existing retention databases are experimentally restrictive and unreliable. A methodology called "retention projection" has the potential to overcome these limitations, but it requires the retention factor (k) vs. T relationship of a compound to calculate its retention time. Direct methods of measuring k vs. T relationships from a series of isothermal runs are tedious and time-consuming. Instead, a series of temperature programs can be used to quickly measure the k vs. T relationships, but they are generally not as accurate when measured this way because they are strongly biased by non-ideal behavior of the GC system in each of the runs. In this work, we overcome that problem by using the retention times of 25 n-alkanes to back-calculate the effective temperature profile and hold-up time vs. T profiles produced in each of the six temperature programs. When the profiles were measured this way and taken into account, the k vs. T relationships measured from each of two different GC-MS instruments were nearly as accurate as the ones measured isothermally, showing less than two-fold more error. Furthermore, temperature-programmed retention times calculated in five other laboratories from the new k vs. T relationships had the same distribution of error as when they were calculated from k vs. T relationships measured isothermally. Free software was developed to make the methodology easy to use. The new methodology potentially provides a relatively fast and easy way to measure unbiased k vs. T relationships. PMID:25496658

Peng, Baijie; Kuo, Mei-Yi; Yang, Panhia; Hewitt, Joshua T; Boswell, Paul G

2014-12-29

116

Solar Neutrinos with Magnetic Moment: Rates and Global Analysis  

E-print Network

A statistical analysis of the solar neutrino data is presented assuming the solar neutrino deficit to be resolved by the resonant interaction of the neutrino magnetic moment with the solar magnetic field. Four field profiles are investigated, all exhibiting a rapid increase across the bottom of the convective zone, one of them closely following the requirements from recent solar physics investigations. First a 'rates only' analysis is performed whose best fits appear to be remarkably better than all fits from oscillations. A global analysis then follows with the corresponding best fits of a comparable quality to the LMA one. Despite the fact that the resonant spin flavour precession does not predict any day/night effect, the separate SuperKamiokande day and night data are included in the analysis in order to allow for a direct comparison with oscillation scenarios. Remarkably enough, the best fit for rates and global analysis which is compatible with most astrophysical bounds on the neutrino magnetic moment is obtained from the profile which most closely follows solar physics requirements. Allowing for a peak field value of $3\\times10^5G$, it is found in this case that $\\Delta m^2_{21}=1.45\\times10^{-8}eV^2$, $\\mu_{\

Joao Pulido

2002-01-23

117

Crack spectra analysis  

SciTech Connect

Crack spectra derived from velocity data have been shown to exhibit systematics which reflect microstructural and textural differences between samples (Warren and Tiernan, 1980). Further research into both properties and information content of crack spectra have yielded the following: Spectral features are reproducible even at low pressures; certain observed spectral features may correspond to non-in-situ crack populations created during sample retrieval; the functional form of a crack spectra may be diagnostic of the sample's grain texture; hysteresis is observed in crack spectra between up and down pressure runs - it may be due to friction between the faces of closed crack populations.

Tiernan, M.

1980-09-01

118

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

119

Optical Spectra of Supernovae  

Microsoft Academic Search

The temporal evolution of the optical spectra of various types of supernovae (SNe) is illustrated, in part to aid observers classifying supernova candidates. Type II SNe are defined by the presence of hydrogen, and they exhibit a very wide variety of photometric and spectroscopic properties. Among hydrogen-deficient SNe (Type I), three subclasses are now known: those whose early-time spectra show

Alexei V. Filippenko

1997-01-01

120

Novel unbiased equations to calculate triglyceride-rich lipoprotein cholesterol from routine non-fasting lipids  

PubMed Central

Background Non-fasting triglyceride-rich lipoproteins cholesterol (TRL-C) contributes to cardiovascular risk, in that it includes remnant cholesterol (RC). TRL-C is computed as total C - [LDL-C?+?HDL-C]. Such calculation applies only if LDL-C is directly measured, or obtained from a non-Friedewald’s formula, a method as yet never benchmarked against independent markers of TRL burden. Methods The Discriminant Ratio (DR) methodology was used in 120 type 2 diabetic patients in order: (i) to compute TRL-C from non-fasting lipids; (ii) to establish the performance of TRL-C and TRL-C/apoA-I (vs. TG-based markers) to grade TRLs and atherogenic dyslipidemia (AD); and (iii) to relate TRL-C with non-fasting TG. Results Depending on apoB100 availability, TRL-C (mg/dL) can be derived from non-fasting lipids in two ways: (a) total cholesterol (TC) - [(0.0106 * TC - 0.0036 * TG?+?0.017 * apoB100 - 0.27) * 38.6] - HDL-C; and (b) TC - [(0.0106 * TC - 0.0036 * TG?+?0.017 * [0.65 * (TC - HDL-C)?+?6.3] - 0.27) * 38.6] - HDL-C. Discrimination between log[TG] and TRL-C was similar (DR 0.94 and 0.84, respectively), whereas that of log[TG]/HDL-C was better than TRL-C/apoA-I (DR 1.01 vs. 0.65; p 0.0482). All Pearson’s correlations between pairs reached unity, allowing formulation of two unbiased equivalence equations: (a) TRL-C?=?97.8 * log[TG] - 181.9; and (b) TRL-C/apoA-I?=?8.15 * (log[TG]/HDL-C) - 0.18. Conclusions TRL-C and log[TG] are as effective and interchangeable for assessing remnant atherogenic particles. For grading TRL-AD, it is best to use log[TG]/HDL-C, inherently superior to TRL-C/apoA-I, while measuring the same underlying variable. PMID:24612479

2014-01-01

121

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

PubMed

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 [SN (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 SN (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 SN (RER). These results indicate that rat cerebellar basket cells endure important age-related changes. The significant decrease in the SN (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. PMID:11465864

Henrique, R M; Rocha, E; Reis, A; Marcos, R; Oliveira, M H; Silva, M W; Monteiro, R A

2001-06-01

122

THE OPTICALLY UNBIASED GAMMA-RAY BURST HOST (TOUGH) SURVEY. I. SURVEY DESIGN AND CATALOGS  

SciTech Connect

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 K{sub s} magnitudes and redshifts. We detect the host galaxies for 80% of the GRBs in the sample, although only 42% have K{sub s} -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{alpha} emission line and we can exclude an early indication that Ly{alpha} emission is ubiquitous among GRB hosts, but confirm that Ly{alpha} is stronger in GRB-selected galaxies than in flux-limited samples of Lyman break galaxies.

Hjorth, Jens; Malesani, Daniele; Fynbo, Johan P. U.; Kruehler, Thomas; Milvang-Jensen, Bo; Watson, Darach [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen O (Denmark); Jakobsson, Pall; Schulze, Steve [Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 3, 107 Reykjavik (Iceland); Jaunsen, Andreas O. [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway); Gorosabel, Javier [Instituto de Astrofisica de Andalucia (IAA-CSIC), P.O. Box 03004, E-18080 Granada (Spain); Levan, Andrew J. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Michalowski, Michal J. [SUPA, Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ (United Kingdom); Moller, Palle [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching by Muenchen (Germany); Tanvir, Nial R., E-mail: jens@dark-cosmology.dk [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom)

2012-09-10

123

Validation of the Isotropic Fractionator: Comparison with Unbiased Stereology and DNA Extraction for Quantification of Glial Cells  

PubMed Central

Background The “isotropic fractionator” (IF) is a novel cell counting technique that homogenizes fixed tissue, recovers cell nuclei in solution, and samples and quantifies nuclei by extrapolation. Studies using this technique indicate that the ratio of glia to neurons in the human brain is approximately 1:1 rather than the 10:1 or 50:1 ratio previously assumed. Although some results obtained with the IF have been similar to those obtained by stereology, the IF has never been calibrated or validated. It is conceivable that only a fraction of glial cell nuclei are recovered intact or recognized after the homogenization step. New Method To rule out this simple explanation for the claim of a 1:1 glia-neuron ratio, we compared cell numbers obtained from adjacent, weight-normalized samples of human and macaque monkey white matter using three techniques: the IF, unbiased stereology of histological sections in exhaustively sectioned samples, and cell numbers calculated from DNA extraction. Results and comparison of methods In primate forebrains, the IF yielded 73,000–90,000 nuclei/mg white matter, unbiased stereology yielded 75,000–92,000 nuclei/mg, with coefficients of error ranging from 0.013–0.063, while DNA extraction yielded only 4,000–23,000 nuclei/mg in fixed white matter tissues. Conclusions Since the IF revealed about 100% of the numbers produced by unbiased stereology, there is no significant underestimate of glial cells. This confirms the notion that the human brain overall contains glial cells and neurons with a ratio of about 1:1 far from the originally assumed ratio of 10:1 in favor of glial cells. PMID:24239779

Bahney, Jami; von Bartheld, Christopher S.

2014-01-01

124

Unbiased estimates of long-term net survival of hematological malignancy patients detailed by major subtypes in France.  

PubMed

Long-term population-based survival data detailed by cancer subtype are important to measure the overall outcomes of malignancy managements. We provide net survival estimates at 1, 3, 5 and 10-year postdiagnosis on 37,549 hematological malignancy (HM) patients whose ages were >15 years, diagnosed between 1989 and 2004 and actively followed until 2008 by French population-based cancer registries. These are, to our knowledge, the first unbiased estimates of 10-year net survival in HMs detailed by subtypes. HMs were classified according to the International Classification of Diseases-Oncology 3. Net survival was estimated with the unbiased Pohar-Perme method. The results are reported by sex and age classes. The changes of these indicators by periods of diagnosis were tabulated and the trends of the net mortality rates over time since diagnosis graphed. In all, 5- and 10-year age-standardized net survivals after HMs varied widely from 81 and 76% for classical Hodgkin lymphoma (CHL) to 18 and 14% for acute myeloid leukemia (AML). Even in HMs with the most favorable prognoses, the net survival decreased between 5- and 10-year postdiagnosis. Women had better prognoses than men and age at diagnosis was an unfavorable prognostic factor for most HMs. In patients <55 years old, the net mortality rate decreased to null values 5-year postdiagnosis in AML and 10-year postdiagnosis in CHL, precursor non-HL, chronic myelogenous leukemia, diffuse large B-cell lymphoma and follicular lymphoma. The prognoses improved for various HMs over the study period. The obtained unbiased indicators are important to evaluate national cancer plans. PMID:23034773

Monnereau, Alain; Troussard, Xavier; Belot, Aurélien; Guizard, Anne-Valérie; Woronoff, Anne-Sophie; Bara, Simona; Lapôtre-Ledoux, Bénédicte; Iwaz, Jean; Tretarre, Brigitte; Maynadié, Marc

2013-05-15

125

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

126

Statistical Properties of Maximum Likelihood Estimators of Power Law Spectra Information  

NASA Technical Reports Server (NTRS)

A simple power law model consisting of a single spectral index, a is believed to be an adequate description of the galactic cosmic-ray (GCR) proton flux at energies below 10(exp 13) eV, with a transition at the knee energy, E(sub k), to a steeper spectral index alpha(sub 2) greater than alpha(sub 1) above E(sub k). The Maximum likelihood (ML) procedure was developed for estimating the single parameter alpha(sub 1) of a simple power law energy spectrum and generalized to estimate the three spectral parameters of the broken power law energy spectrum from simulated detector responses and real cosmic-ray data. The statistical properties of the ML estimator were investigated and shown to have the three desirable properties: (P1) consistency (asymptotically unbiased). (P2) efficiency asymptotically attains the Cramer-Rao minimum variance bound), and (P3) asymptotically normally distributed, under a wide range of potential detector response functions. Attainment of these properties necessarily implies that the ML estimation procedure provides the best unbiased estimator possible. While simulation studies can easily determine if a given estimation procedure provides an unbiased estimate of the spectra information, and whether or not the estimator is approximately normally distributed, attainment of the Cramer-Rao bound (CRB) can only he ascertained by calculating the CRB for an assumed energy spectrum-detector response function combination, which can be quite formidable in practice. However. the effort in calculating the CRB is very worthwhile because it provides the necessary means to compare the efficiency of competing estimation techniques and, furthermore, provides a stopping rule in the search for the best unbiased estimator. Consequently, the CRB for both the simple and broken power law energy spectra are derived herein and the conditions under which they are attained in practice are investigated. The ML technique is then extended to estimate spectra information from an arbitrary number of astrophysics data sets produced by vastly different science instruments. This theory and its successful implementation will facilitate the interpretation of spectral information from multiple astrophysics missions and thereby permit the derivation of superior spectral parameter estimates based on the combination of data sets.

Howell, L. W.

2002-01-01

127

"Decoupled" Proton NMR Spectra  

NASA Astrophysics Data System (ADS)

High-resolution proton NMR spectra are recorded in a new form where all resonances are singlets at the chemical-shift frequencies, with no spin-spin splittings. These "decoupled" proton spectra are derived from two-dimensional J spectra after real Fourier transformation (without frequency discrimination in F1) so that each spin multiplet lies along both the 45° and the 135° diagonal, forming a pattern similar to St. Andrew's cross, with C 4 symmetry. The chemical shifts are located by searching for these centers of symmetry with a postacquisition data-processing algorithm. This is designed to facilitate the separation of overlapping and interpenetrating spin multiplets. The method is illustrated with applications to the 400 MHz high-resolution proton spectra of dehydrotestosterone and 4-androsten-3,17-dione. It is also possible to separate the spectra of components in a mixture and this is illustrated by breaking down the spectrum of an aqueous solution of D-glucose into subspectra from the ? and ? anomers, in order to follow the time evolution of the mutarotation.

Woodley, M.; Freeman, R.

128

An unbiased infrared H2 search for embedded flows from young stars in Orion A  

NASA Astrophysics Data System (ADS)

The presence of outflows, often in the form of well-collimated jets, is a phenomenon commonly associated with the birth of young stars. Emission from shock-excited molecular hydrogen at near-infrared wavelengths is one of the signposts of the presence of such an outflow, and generally can be observed even if the flow is obscured at optical wavelengths. In this thesis, I present the results of an unbiased, sensitive, wide-field search for flows from protostellar objects in the v=1-0 S(1) line at a wavelength of 2.12 ?m, covering a 1 square degree area of the Orion A giant molecular cloud. Further data covering a wide wavelength range are used to search for the driving sources of the flows. The aim of this work is to obtain a sample of outflows which is free from biases as far as possible, to derive the typical properties of the outflows, to search for evolutionary trends, and to examine the impact of outflows on the ambient cloud. The first result from this survey is that outflows are indeed common in star forming regions: more than 70 candidate jets are identified. Most of them have a fairly ill-defined morphology rather than a regular or symmetric structure, which is interpreted to be due to the turbulent, clumpy ambient medium into which the jets are propagating. The jets are randomly oriented. In particular, no alignment of the jets with the large scale ambient magnetic field is found, suggesting that the spin and symmetry axis in a protostellar object is determined by random, turbulent motions in the cloud. Candidate driving sources are identified for 49 jets, and their evolutionary stage and bolometric luminosity is estimated. The jet lengths and H2 luminosities evolve as a function of the age of the driving source: the jets grow quickly from zero length to a size of a few parsec and then slowly shorten again. The jets are very luminous early on and fade during the protostellar evolution. The evolution in length and H2 luminosity is attributed to an early phase of strong accretion, which subsequently decreases. The shortening of the jets with time requires the presence of a continuous deceleration of the jets. A simple model of the simultaneous evolution of a protostar, its circumstellar environment, and its outflow ( Smith 2000 ) can reproduce the measured values of H2 luminosity and driving source luminosity under the assumption of a strong accretion plus high ejection efficiency phase early in the protostellar evolution. Tatematsu et al. (1993) found 125 dense cloud cores in the survey area. The jet driving sources are found to have formed predominantly in quiet cores with a low ratio of internal kinetic energy to gravitational potential energy; these are the cores with higher masses. The cores which are associated with jets have on average larger linewidths than cores without jets. This is due to the preferred presence of jets in more massive cores, which generally have larger linewidths. There is no evidence for additional internal motions excited by the interaction of the jets with the cores. The jet H2 luminosity and the core linewidth (as predicted by theory) are related, if Class 0 and Class I jets are considered separately; the relation lies at higher values of the H2 luminosity for the Class 0 jets than for Class I jets. This also suggests a time evolution of the accretion rate, with a strong peak early on and a subsequent decay. Finally, the impact of a protostellar jet population on a molecular cloud is considered. Under the conservative assumption of strict forward momentum conservation, the jets appear to fail to provide sufficient momentum to replenish decaying turbulence on the scales of a giant molecular cloud and on the scales of molecular cloud cores. At the intermediate scales of molecular clumps with sizes of a few parsec and masses of a few hundred solar masses, the jets provide enough momentum in a short enough time to potentially replenish turbulence and thus might help to stabilize the clump against further collapse.

Stanke, Thomas

2000-07-01

129

An unbiased infrared H2 search for embedded flows from young stars in Orion A  

NASA Astrophysics Data System (ADS)

The presence of outflows, often in the form of well-collimated jets, is a phenomenon commonly associated with the birth of young stars. Emission from shock-excited molecular hydrogen at near-infrared wavelengths is one of the signposts of the presence of such an outflow, and generally can be observed even if the flow is obscured at optical wavelengths. In this thesis, I present the results of an unbiased, sensitive, wide-field search for flows from protostellar objects in the H2 v=1-0 S(1) line at a wavelength of 2.12 µm, covering a 1 square degree area of the Orion A giant molecular cloud. Further data covering a wide wavelength range are used to search for the driving sources of the flows. The aim of this work is to obtain a sample of outflows which is free from biases as far as possible, to derive the typical properties of the outflows, to search for evolutionary trends, and to examine the impact of outflows on the ambient cloud. The first result from this survey is that outflows are indeed common in star forming regions: more than 70 candidate jets are identified. Most of them have a fairly ill-defined morphology rather than a regular or symmetric structure, which is interpreted to be due to the turbulent, clumpy ambient medium into which the jets are propagating. The jets are randomly oriented. In particular, no alignment of the jets with the large scale ambient magnetic field is found, suggesting that the spin and symmetry axis in a protostellar object is determined by random, turbulent motions in the cloud. Candidate driving sources are identified for 49 jets, and their evolutionary stage and bolometric luminosity is estimated. The jet lengths and H2 luminosities evolve as a function of the age of the driving source: the jets grow quickly from zero length to a size of a few parsec and then slowly shorten again. The jets are very luminous early on and fade during the protostellar evolution. The evolution in length and H2 luminosity is attributed to an early phase of strong accretion, which subsequently decreases. The shortening of the jets with time requires the presence of a continuous deceleration of the jets. A simple model of the simultaneous evolution of a protostar, its circumstellar environment, and its outflow (Smith 2000) can reproduce the measured values of H2 luminosity and driving source luminosity under the assumption of a strong accretion plus high ejection efficiency phase early in the protostellar evolution. Tatematsu et al. (1993) found 125 dense cloud cores in the survey area. The jet driving sources are found to have formed predominantly in quiet cores with a low ratio of internal kinetic energy to gravitational potential energy; these are the cores with higher masses. The cores which are associated with jets have on average larger linewidths than cores without jets. This is due to the preferred presence of jets in more massive cores, which generally have larger linewidths. There is no evidence for additional internal motions excited by the interaction of the jets with the cores. The jet H2 luminosity and the core linewidth (as predicted by theory) are related, if Class 0 and Class I jets are considered separately; the relation lies at higher values of the H2 luminosity for the Class 0 jets than for Class I jets. This also suggests a time evolution of the accretion rate, with a strong peak early on and a subsequent decay. Finally, the impact of a protostellar jet population on a molecular cloud is considered. Under the conservative assumption of strict forward momentum conservation, the jets appear to fail to provide sufficient momentum to replenish decaying turbulence on the scales of a giant molecular cloud and on the scales of molecular cloud cores. At the intermediate scales of molecular clumps with sizes of a few parsec and masses of a few hundred solar masses, the jets provide enough momentum in a short enough time to potentially replenish turbulence and thus might help to stabilize the clump against further collapse. Gasausströmungen, oft in der Form hoch kollimierter Jets, sind ein allg

Stanke, Thomas

2001-04-01

130

WebSpectra  

NSDL National Science Digital Library

This site, created by Barry C. Fam and Craig A. Merlic of the University of California - Los Angeles, was established to provide chemistry students with a library of spectroscopy problems. 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. Hopefully, these problems will provide a useful resource to better understand spectroscopy. The page was given a "Top 5% Chemistry Site" award for its usefulness and content. This is a great resource for anyone interested in either biochemistry or chemistry.

Fam, Barry C.; Merlic, Craig A.

2009-05-07

131

Direct measurement of the dynamics of hole hopping in extended DNA G-tracts. An unbiased random walk.  

PubMed

We report the measurement of distance- and temperature-dependent rate constants for charge separation in capped hairpins in which a stilbene hole acceptor and hole donor are separated by A(3)G(n) diblock polypurine sequences consisting of 3 adenines and 1-19 guanines. The longer diblock systems obey the simplest model for an unbiased random walk, providing a direct measurement of k(hop) = 4.3 × 10(9) s(-1) for a single reversible G-to-G hole hopping step, somewhat faster than the value of 1.2 × 10(9) s(-1) calculated for A-tract hole hopping. The temperature dependence for hopping in A(3)G(13) provides values of E(act) = 2.8 kcal/mol and A = 7 × 10(9) s(-1), consistent with a weakly activated, conformationally gated process. PMID:20863110

Conron, Sarah M Mickley; Thazhathveetil, Arun K; Wasielewski, Michael R; Burin, Alexander L; Lewis, Frederick D

2010-10-20

132

Revisiting AFLP fingerprinting for an unbiased assessment of genetic structure and differentiation of taurine and zebu cattle  

PubMed Central

Background Descendants from the extinct aurochs (Bos primigenius), taurine (Bos taurus) and zebu cattle (Bos indicus) were domesticated 10,000 years ago in Southwestern and Southern Asia, respectively, and colonized the world undergoing complex events of admixture and selection. Molecular data, in particular genome-wide single nucleotide polymorphism (SNP) markers, can complement historic and archaeological records to elucidate these past events. However, SNP ascertainment in cattle has been optimized for taurine breeds, imposing limitations to the study of diversity in zebu cattle. As amplified fragment length polymorphism (AFLP) markers are discovered and genotyped as the samples are assayed, this type of marker is free of ascertainment bias. In order to obtain unbiased assessments of genetic differentiation and structure in taurine and zebu cattle, we analyzed a dataset of 135 AFLP markers in 1,593 samples from 13 zebu and 58 taurine breeds, representing nine continental areas. Results We found a geographical pattern of expected heterozygosity in European taurine breeds decreasing with the distance from the domestication centre, arguing against a large-scale introgression from European or African aurochs. Zebu cattle were found to be at least as diverse as taurine cattle. Western African zebu cattle were found to have diverged more from Indian zebu than South American zebu. Model-based clustering and ancestry informative markers analyses suggested that this is due to taurine introgression. Although a large part of South American zebu cattle also descend from taurine cows, we did not detect significant levels of taurine ancestry in these breeds, probably because of systematic backcrossing with zebu bulls. Furthermore, limited zebu introgression was found in Podolian taurine breeds in Italy. Conclusions The assessment of cattle diversity reported here contributes an unbiased global view to genetic differentiation and structure of taurine and zebu cattle populations, which is essential for an effective conservation of the bovine genetic resources. PMID:24739206

2014-01-01

133

Unbiased Discovery of Interactions at a Control Locus Driving Expression of the Cancer-Specific Therapeutic and Diagnostic Target, Mesothelin  

PubMed Central

Although significant effort is expended on identifying transcripts/proteins that are up-regulated in cancer, there are few reports on systematic elucidation of transcriptional mechanisms underlying such druggable cancer-specific targets. The mesothelin (MSLN) gene offers a promising subject, being expressed in a restricted pattern normally, yet highly overexpressed in almost one-third of human malignancies and a target of cancer immunotherapeutic trials. CanScript, a cis promoter element, appears to control MSLN cancer-specific expression; its related genomic sequences may up-regulate other cancer markers. CanScript is a 20-nt bipartite element consisting of an SP1-like motif and a consensus MCAT sequence. The latter recruits TEAD (TEA domain) family members, which are universally expressed. Exploration of the active CanScript element, especially the proteins binding to the SP1-like motif, thus could reveal cancer-specific features having diagnostic or therapeutic interest. The effcient identification of sequence-specific DNA-binding proteins at a given locus, however, has lagged in biomarker explorations. We used two orthogonal proteomics approaches— unbiased SILAC (stable isotope labeling by amino acids in cell culture)/DNA affnity-capture/mass spectrometry survey (SD-MS) and a large transcription factor protein microarray (TFM)—and functional validation to explore systematically the CanScript interactome. SD-MS produced nine candidates, and TFM, 18. The screens agreed in confirming binding by TEAD proteins and by newly identified NAB1 and NFATc. Among other identified candidates, we found functional roles for ZNF24, NAB1 and RFX1 in MSLN expression by cancer cells. Combined interactome screens yield an effcient, reproducible, sensitive, and unbiased approach to identify sequence-specific DNA-binding proteins and other participants in disease-specific DNA elements. PMID:23025254

Ren, Yunzhao R.; Chaerkady, Raghothama; Hu, Shaohui; Wan, Jun; Qian, Jiang; Zhu, Heng; Pandey, Akhilesh; Kern, Scott E.

2013-01-01

134

Direct recovery of fluctuation spectra from tomographic shear spectra  

SciTech Connect

Forthcoming experiments will enable us to determine high precision tomographic shear spectra. Matter density fluctuation spectra, at various z, should then be recovered from them, in order to constrain the model and determine the DE state equation. Available analytical expressions, however, do the opposite, enabling us to derive shear spectra from fluctuation spectra. Here we find the inverse expression, yielding density fluctuation spectra from observational tomographic shear spectra. The procedure involves SVD techniques for matrix inversion. We show in detail how the approach works and provide a few examples.

Mezzetti, Marino; Bonometto, Silvio A.; Murante, Giuseppe [Department of Physics, Astronomy Unit, Trieste University, Via Tiepolo 11, I 34143 Trieste (Italy); Casarini, Luciano, E-mail: mezzetti@oats.inaf.it, E-mail: bonometto@oats.inaf.it, E-mail: casarini@mib.infn.it, E-mail: murante@oats.inaf.it [Departamento de Fisica, UFES, Avenida Fernando Ferrari 514, Vitória, Espírito Santo (Brazil)

2012-06-01

135

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

136

A Classifier Based on Accurate Mass Measurements to Aid Large Scale, Unbiased Glycoproteomics*  

PubMed Central

Determining which glycan moieties occupy specific N-glycosylation sites is a highly challenging analytical task. Arguably, the most common approach involves LC-MS and LC-MS/MS analysis of glycopeptides generated by proteases with high cleavage site specificity; however, the depth achieved by this approach is modest. Nonglycosylated peptides are a major challenge to glycoproteomics, as they are preferentially selected for data-dependent MS/MS due to higher ionization efficiencies and higher stoichiometric levels in moderately complex samples. With the goal of improving glycopeptide coverage, a mass defect classifier was developed that discriminates between peptides and glycopeptides in complex mixtures based on accurate mass measurements of precursor peaks. By using the classifier, glycopeptides that were not fragmented in an initial data-dependent acquisition run may be targeted in a subsequent analysis without any prior knowledge of the glycan or protein species present in the mixture. Additionally, from probable glycopeptides that were poorly fragmented, tandem mass spectra may be reacquired using optimal glycopeptide settings. We demonstrate high sensitivity (0.892) and specificity (0.947) based on an in silico dataset spanning >100,000 tryptic entries. Comparable results were obtained using chymotryptic species. Further validation using published data and a fractionated tryptic digest of human urinary proteins was performed, yielding a sensitivity of 0.90 and a specificity of 0.93. Lists of glycopeptides may be generated from an initial proteomics experiment, and we show they may be efficiently targeted using the classifier. Considering the growing availability of high accuracy mass analyzers, this approach represents a simple and broadly applicable means of increasing the depth of MS/MS-based glycoproteomic analyses. PMID:23438733

Froehlich, John W.; Dodds, Eric D.; Wilhelm, Mathias; Serang, Oliver; Steen, Judith A.; Lee, Richard S.

2013-01-01

137

Parmeterization of spectra  

NASA Technical Reports Server (NTRS)

Following reception and analog to digital conversion (A/D) conversion, atmospheric radar backscatter echoes need to be processed so as to obtain desired information about atmospheric processes and to eliminate or minimize contaminating contributions from other sources. Various signal processing techniques have been implemented at mesosphere-stratosphere-troposphere (MST) radar facilities to estimate parameters of interest from received spectra. Such estimation techniques need to be both accurate and sufficiently efficient to be within the capabilities of the particular data-processing system. The various techniques used to parameterize the spectra of received signals are reviewed herein. Noise estimation, electromagnetic interference, data smoothing, correlation, and the Doppler effect are among the specific points addressed.

Cornish, C. R.

1983-01-01

138

Activity: Graphing Spectra  

NSDL National Science Digital Library

This activity introduces two different representations of spectra: the photographic representation, such as the rainbow, and the graphical representation used more often by astronomers. A rainbow is often given as an everyday example of a spectrum. Most students have seen a rainbow, so this example is used to help make the unfamiliar more familiar. However, the spectra that scientists use, which students will see in this lesson plan, appear very different than a rainbow. In this activity, students will explore for themselves two different representations of the same spectrum, noting advantages and disadvantages of each. They will explore the differences and similarities of both these representations, and will develop a more intuitive feel for a graphical representation, which may not yet be familiar to them.

2007-02-03

139

Barnacle Bill Spectra  

NASA Technical Reports Server (NTRS)

These IMP spectra show the characteristics of the rock surface measured by the Alpha Proton X-Ray Spectrometer (blue), the soil trapped in pits on the rock surface (red), and the deposit of bright drift on the top of the rock. The area measured by the APXS has the properties expected for nearly unweathered igneous rock, and the soil trapped in the pits is intermediate to the unweathered rock and the highly weathered drift material.

1997-01-01

140

Auroral Colors and Spectra  

NSDL National Science Digital Library

This site, co-produced by the NCAR High Altitude Observatory and the COMET Program, provides an explanation of how auroral colors are produced. The emission of specific colors of light is discussed in relation to oxygen and nitrogen emission spectra. Numerous images, graphs, and a video of an aurora are included. The site is part of "Physics of the Aurora: Earth Systems," an interactive learning module about the aurora.

2007-01-26

141

Einstein spectra of quasars  

NASA Technical Reports Server (NTRS)

The results of the initial stage of the CfA survey of quasar energy distributions are reviewed. Einstein imaging proportional counter spectra of 33 quasars have been studied by fitting a single power law slope and absorption by an equivalent column density of neutral hydrogen. Comparison with the higher energy HEAO-A2 data leads to a two-component model for the X-ray spectrum. The X-ray column density is systematically lower than the 21-cm measured Galactic column density along the same line of sight.

Wilkes, Belinda J.

1988-01-01

142

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.

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

2004-08-01

143

Experimental strategies for functional annotation and metabolism discovery: targeted screening of solute binding proteins and unbiased panning of metabolomes.  

PubMed

The rate at which genome sequencing data is accruing demands enhanced methods for functional annotation and metabolism discovery. Solute binding proteins (SBPs) facilitate the transport of the first reactant in a metabolic pathway, thereby constraining the regions of chemical space and the chemistries that must be considered for pathway reconstruction. We describe high-throughput protein production and differential scanning fluorimetry platforms, which enabled the screening of 158 SBPs against a 189 component library specifically tailored for this class of proteins. Like all screening efforts, this approach is limited by the practical constraints imposed by construction of the library, i.e., we can study only those metabolites that are known to exist and which can be made in sufficient quantities for experimentation. To move beyond these inherent limitations, we illustrate the promise of crystallographic- and mass spectrometric-based approaches for the unbiased use of entire metabolomes as screening libraries. Together, our approaches identified 40 new SBP ligands, generated experiment-based annotations for 2084 SBPs in 71 isofunctional clusters, and defined numerous metabolic pathways, including novel catabolic pathways for the utilization of ethanolamine as sole nitrogen source and the use of d-Ala-d-Ala as sole carbon source. These efforts begin to define an integrated strategy for realizing the full value of amassing genome sequence data. PMID:25540822

Vetting, Matthew W; Al-Obaidi, Nawar; Zhao, Suwen; San Francisco, Brian; Kim, Jungwook; Wichelecki, Daniel J; Bouvier, Jason T; Solbiati, Jose O; Vu, Hoan; Zhang, Xinshuai; Rodionov, Dmitry A; Love, James D; Hillerich, Brandan S; Seidel, Ronald D; Quinn, Ronald J; Osterman, Andrei L; Cronan, John E; Jacobson, Matthew P; Gerlt, John A; Almo, Steven C

2015-01-27

144

Unbiased and efficient estimation of the volume of the fibroid uterus using the cavalieri method and magnetic resonance imaging.  

PubMed

The aim of our study was to develop a reliable technique for measuring volume of the fibroid uterus using Magnetic Resonance Imaging. We applied the Cavalieri method and standard calliper technique to measure the volume of the uterus and largest fibroid in 26 patients, and results were compared with "gold-standard" planimetry measurements. We found Cavalieri measurements to be unbiased, while calliper measurements systematically underestimated uterine volume (- 13.2%, P < 10(-5)) and had greater variance. Repeatability was similar for the 2 techniques (standard deviation [SD] = 4.0%-6.9%). Reproducibility of Cavalieri measurements was higher for measurement of uterine (SD = 9.0%) than fibroid volume (SD = 19.1%), whereas the reproducibility of calliper measurements was higher for fibroid (SD = 9.1%) than uterine volume (SD = 15.9%). The additional measurement time for the Cavalieri method was approximately 1 to 2 minutes. In conclusion, the Cavalieri method permits more accurate measurement of uterine and fibroid volumes and is suitable for application in both clinical practice and scientific research. PMID:25332217

Thrippleton, Michael J; Munro, Kirsty I; McKillop, Graham; Newby, David E; Marshall, Ian; Roberts, Neil; Critchley, Hilary O D

2015-01-01

145

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. PMID:23843970

Gushchin, Ivan; Gordeliy, Valentin; Grudinin, Sergei

2013-01-01

146

Detection of variations in cognitive workload using multi-modality physiological sensors and a large margin unbiased regression machine.  

PubMed

Physiological sensor based workload estimation technology provides a real-time means for assessing cognitive workload and has a broad range of applications in cognitive ergonomics, mental health monitoring, etc. In this paper we report a study on detecting changes in workload using multi-modality physiological sensors and a novel feature extraction and classification algorithm. We conducted a cognitive workload experiment involving multiple subjects and collected an extensive data set of EEG, ECG and GSR signals. We show that the GSR signal is consistent with the variations of cognitive workload in 75% of the samples. To explore cardiac patterns in ECG that are potentially correlated with the cognitive workload process, we computed various heart-rate-variability features. To extract neuronal activity patterns in EEG related to cognitive workload, we introduced a filter bank common spatial pattern filtering technique. As there can be large variations in e.g. individual responses to the cognitive workload, we propose a large margin unbiased recursive feature extraction and regression method. Our leave-one-subject-out cross validation test shows that, using the proposed method, EEG can provide significantly better prediction of the cognitive workload variation than ECG, with 87.5% vs 62.5% in accuracy rate. PMID:25570618

Haihong Zhang; Yongwei Zhu; Maniyeri, Jayachandran; Cuntai Guan

2014-08-01

147

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

PubMed Central

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.

2013-01-01

148

Landslide susceptibility assessment in the Upper Orcia Valley (Southern Tuscany, Italy) through conditional analysis: a contribution to the unbiased selection of causal factors  

NASA Astrophysics Data System (ADS)

In this work the conditional multivariate analysis was applied to evaluate landslide susceptibility in the Upper Orcia River Basin (Tuscany, Italy), where widespread denudation processes and agricultural practices have a mutual impact. We introduced an unbiased procedure for causal factor selection based on some intuitive statistical indices. This procedure is aimed at detecting among different potential factors the most discriminant ones in a given study area. Moreover, this step avoids generating too small and statistically insignificant spatial units by intersecting the factor maps. Finally, a validation procedure was applied based on the partition of the landslide inventory from multi-temporal aerial photo interpretation. Although encompassing some sources of uncertainties, the applied susceptibility assessment method provided a satisfactory and unbiased prediction for the Upper Orcia Valley. The results confirmed the efficiency of the selection procedure, as an unbiased step of the landslide susceptibility evaluation. Furthermore, we achieved the purpose of presenting a conceptually simple but, at the same time, effective statistical procedure for susceptibility analysis to be used as well by decision makers in land management.

Vergari, F.; Della Seta, M.; Del Monte, M.; Fredi, P.; Lupia Palmieri, E.

2011-05-01

149

Development of fatigue loading spectra  

SciTech Connect

The present work on fatigue-loading spectra encompasses the current status of standardized stress-time histories, European approaches to standard loading spectrum development, transport aircraft airframe fatigue test spectra, the TURBISTAN fatigue-loading standard for fighter-aircraft engine disks, an automated procedure for the creation of flight-by-flight spectra, and the development of a wave-action standard history for fatigue testing relevant to tubular structures in the North Sea. Also treated is the use of the TURBISTAN mission spectra to evaluate fatigue crack growth in a rotating disk, fatigue-spectra development for airborne stores, a simplified analysis of fatigue-loading spectra, variable-amplitude load models for fatigue-damage crack growth, the tracking time service histories for multiaxis fatigue problems, and the compilation of procedures for fatigue crack propagation testing under complex load sequences.

Potter, J.M.; Watanabe, R.T.

1989-01-01

150

Development of fatigue loading spectra  

Microsoft Academic Search

The present work on fatigue-loading spectra encompasses the current status of standardized stress-time histories, European approaches to standard loading spectrum development, transport aircraft airframe fatigue test spectra, the TURBISTAN fatigue-loading standard for fighter-aircraft engine disks, an automated procedure for the creation of flight-by-flight spectra, and the development of a wave-action standard history for fatigue testing relevant to tubular structures in

J. M. Potter; R. T. Watanabe

1989-01-01

151

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. PMID:24146806

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

2013-01-01

152

Unbiased tensor-based morphometry: Improved robustness and sample size estimates for Alzheimer’s disease clinical trials  

PubMed Central

Various neuroimaging measures are being evaluated for tracking Alzheimer’s disease (AD) progression in therapeutic trials, including measures of structural brain change based on repeated scanning of patients with magnetic resonance imaging (MRI). Methods to compute brain change must be robust to scan quality. Biases may arise if any scans are thrown out, as this can lead to the true changes being overestimated or underestimated. Here we analyzed the full MRI dataset from the first phase of Alzheimer’s Disease Neuroimaging Initiative (ADNI-1) from the first phase of Alzheimer’s Disease Neuroimaging Initiative (ADNI-1) and assessed several sources of bias that can arise when tracking brain changes with structural brain imaging methods, as part of a pipeline for tensor-based morphometry (TBM). In all healthy subjects who completed MRI scanning at screening, 6, 12, and 24 months, brain atrophy was essentially linear with no detectable bias in longitudinal measures. In power analyses for clinical trials based on these change measures, only 39 AD patients and 95 mild cognitive impairment (MCI) subjects were needed for a 24-month trial to detect a 25% reduction in the average rate of change using a two-sided test (?=0.05, power=80%). Further sample size reductions were achieved by stratifying the data into Apolipoprotein E (ApoE) ?4 carriers versus non-carriers. We show how selective data exclusion affects sample size estimates, motivating an objective comparison of different analysis techniques based on statistical power and robustness. TBM is an unbiased, robust, high-throughput imaging surrogate marker for large, multi-site neuroimaging studies and clinical trials of AD and MCI. PMID:23153970

Hua, Xue; Hibar, Derrek P.; Ching, Christopher R.K.; Boyle, Christina P.; Rajagopalan, Priya; Gutman, Boris A.; Leow, Alex D.; Toga, Arthur W.; Jack, Clifford R.; Harvey, Danielle; Weiner, Michael W.; Thompson, Paul M.

2013-01-01

153

Using propensity score matching to estimate an "unbiased effect-size" between women's employment and partner violence in Tanzania.  

PubMed

Estimates of the effect of employment on women's risk of partner violence in cross-sectional studies are subject to potential "self-selection bias." Women's personal choice of whether to pursue employment or not may create fundamental differences between the group of women who are employed and those who are not employed that standard regression methods cannot account for even after adjusting for confounding. The aim of this study is to demonstrate the utility of propensity score matching (PSM), a technique used widely in econometrics, to address this bias in cross-sectional studies. We use PSM to estimate an unbiased effect-size of women's employment on their risk of experiencing partner violence in urban and rural Tanzania using data from the 2010 Tanzania Demographic and Health Survey (DHS). Three different measures of women's employment were analyzed: whether they had engaged in any productive work outside of the home in the past year, whether they received payment in cash for this productive work, and whether their employment was stable. Women who worked outside of the home were significantly different from those who did not. In both urban and rural Tanzania, women's risk of violence appears higher among women who worked in the past year than among those who did not, even after using PSM to account for underlying differences in these two groups of women. Being paid in cash reversed this effect in rural areas whereas stability of employment reduced this risk in urban centers. The estimated size of effect varied by type of matching estimator, but the direction of the association remained largely consistent. This study's findings suggest substantial self-selection into employment. PSM methods, by compensating for this bias, appear to be a useful tool for estimating the relationship between women's employment and partner violence in cross-sectional studies. PMID:24729130

Vyas, Seema; Heise, Lori

2014-11-01

154

[Oscillation spectra of metal-porphyrin dication spectra].  

PubMed

Spectra of resonance spontaneous combination scattering (RSCS) of dications of metal--derivatives of tetraphenyl and ethioporphyrine (Ni-TPhP, Cu-TPhP, Cu-EP and VO-EP0 and IR-spectra of absorption of Ni-TPhP and Cu-EP dications were obtained. It was found that transformation of porphyrine neutral molecules into dications is accompanied with the appearance of new absorption bands in IR-spectra analogs of which are in RSCS spectra of dications. In some cases it points to the disturbance of alternative prohibition to oscillative transitions and to structural changes which result in the loss of symmetry centre by the molecule when it is transformed into the dication. A comparison of RSCS spectra of dications and dianions of VO-EP suggests that they have different structure. PMID:7397250

Aleksandrov, I V; Eletski?, N P; Sidorov, A N

1980-01-01

155

Two components in meteor spectra  

Microsoft Academic Search

Through an analysis of fireball spectra it was found that meteor heads consist of two parts with quite different temperatures. The spectra of both parts can be fitted with a simple thermal equilibrium model. The temperature of the main spectrum is about 4000 K, and that of the second spectrum is about 10,000 K. There is little evidence for a

Jiri Borovicka

1994-01-01

156

Spitzer Infrared Spectra of Five Hard X-ray Selected AGN  

NASA Astrophysics Data System (ADS)

We present the full low-resolution (60 < R < 127) and high-resolution (R 600) spectra of five active galactic nuclei (AGN) taken with the Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope. The sample was selected from the Swift BAT AGN catalog, derived from a hard X-ray (14-195 keV), all-sky mosaic. This nearly unbiased catalog can detect all but the most Compton thick AGN (NH >1024 cm -2) which will be obscured in this energy regime. The AGN studied are NGC 4395 (z=0.001064), NGC 4102 (z=0.002823), ESO 005 G004 (z=0.006228), UGC 06728 (z=0.006518), and MCG -05-23-016 (z=0.008486) representing the nearest of the 9-month BAT AGN catalog objects with no previous Spitzer IRS observations. We model the continuum IR flux of these objects using XSPEC, a software package primarily used to model X-ray spectra. Our modeling demonstrates a great variety of spectral shapes even in this small sample. Future work will combine our IR data with multi-wavelength photometry in order to isolate the AGN component of the IR flux from the host galaxy light. These five objects are the first of 65 without previous IRS spectra to be analyzed in this ongoing research.

Riley, Seamus; Weaver, K. A.; Malumuth, E. M.; Arnaud, K. A.

2010-01-01

157

Analysis of the interactions of bright photovoltaic low-divergence soliton-like fields in unbiased self-defocusing photorefractive BaTiO3  

NASA Astrophysics Data System (ADS)

Optical spatial solitons are of interest at present due their possible application to integrated all optical circuitry where light controls light. This optical circuitry utilises the various novel properties of the optical spatial soliton, such as rewritable waveguides, and phase dependent interactions. Of all the types of optical spatial solitons, photorefractive (PR) solitons are the subject of much research due to their ease of production and stability. They are readily produced in either self-focusing PR media (photovoltaic solitons), or self-defocusing PR media with an applied external bias (screening solitons). The external bias, typically an applied DC filed, is used to manipulate the self-defocusing PR media to act like self-focusing PR media. However, solitons produced in self-focusing PR media run the risk of over focusing causing permanent damage to the PR media, while applying an external bias to the PR media requires many additional components, increasing the complexity of the system. Recently, we outlined for the first time a theoretical model of soliton-like low divergence fields in unbiased self-defocusing PR media. Numerical analysis of these soliton-like fields showed stability over distances well in excess of both the confocal distance of the beam, and the physical size of the PR media. The present research examines the existence of the low-divergence soliton-like fields and the fundamental nature of the interactions of these low-divergence soliton-like fields in unbiased PR self-defocusing media. Here we show that low-divergence soliton-like fields can be produced in unbiased self-defocusing photorefractive media, and that when the two of these soliton-like fields interact within the PR media, they are forced away from each other.

Jones, M. W.; Jaatinen, E.; Michael, G.

2009-02-01

158

Elemental Absorption and Emission Spectra  

NSDL National Science Digital Library

This applet displays the periodic table of elements. Clicking on an element will show its line spectrum (as a neutral species). Both absorption and emission spectra can be observed. The cursor can be used to measure the wavelengths.

159

Spectra ID of recent SN  

NASA Astrophysics Data System (ADS)

P. Challis, Harvard-Smithsonian Center for Astrophysics (CfA), on behalf of the CfA Supernova Group, report spectra (range 320-860 nm) of various SN obtained during Dec. 24-27 UT by P. Challis, S. Gottilla (MMTO.org), and E. Marin (MMTO.org) with the MMT 6.5-m telescope (+ Blue Channel). Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J.

Challis, Peter

2013-12-01

160

An unbiased method for the quantitation of disease phenotypes using a custom-built macro plugin for the program ImageJ.  

PubMed

Accurate evaluation of disease phenotypes is considered a key step to study plant-microbe interactions, as the rate of host colonization by the pathogenic microbe directly reflects whether the defense response of the plant is compromised. Although several techniques were developed to quantitate the amount of infection, only a few of them are inherently suitable for large disease screens. Here, I describe an unbiased method to quantitate disease phenotypes which manifest themselves by visible symptoms contrasting with the remaining unaffected parts of the host tissue. The method utilizes a macro plugin written for the image processing program "ImageJ" to calculate two values which determine the disease index for a specific treatment. In case the disease symptoms are not clear, a transgenic pathogenic fungus expressing the GUS gene is suitable for high-throughput disease screens, since staining for GUS activity facilitates an easy detection of the blue-stained pathogen. I illustrate the versatility of this method by analyzing a data set from a functional silencing screening experiment in resistant tomato that was inoculated with a GUS-expressing strain of the fungus Cladosporium fulvum. The method calculates a disease index for each silenced plant and thereby provides a basis for the unbiased identification of candidate host genes required for full resistance to this fungus. PMID:22183684

Abd-El-Haliem, Ahmed

2012-01-01

161

Toward a more accurate view of human B-cell repertoire by next-generation sequencing, unbiased repertoire capture and single-molecule barcoding.  

PubMed

B-cell repertoire analysis using next-generation sequencing has become a valuable tool for interrogating the genetic record of humoral response to infection. However, key obstacles such as low throughput, short read length, high error rate, and undetermined bias of multiplex PCR method have hindered broader application of this technology. In this study, we report several technical advances in antibody repertoire sequencing. We first demonstrated the ability to sequence antibody variable domains using the Ion Torrent PGM platform. As a test case, we analyzed the PGT121 class of antibodies from IAVI donor 17, an HIV-1-infected individual. We then obtained "unbiased" antibody repertoires by sequencing the 5'-RACE PCR products of B-cell transcripts from IAVI donor 17 and two HIV-1-uninfected individuals. We also quantified the bias of previously published gene-specific primers by comparing the repertoires generated by 5'-RACE PCR and multiplex PCR. We further developed a single-molecule barcoding strategy to reduce PCR-based amplification noise. Lastly, we evaluated several new PGM technologies in the context of antibody sequencing. We expect that, based upon long-read and high-fidelity next-generation sequencing technologies, the unbiased analysis will provide a more accurate view of the overall antibody repertoire while the barcoding strategy will facilitate high-resolution analysis of individual antibody families. PMID:25345460

He, Linling; Sok, Devin; Azadnia, Parisa; Hsueh, Jessica; Landais, Elise; Simek, Melissa; Koff, Wayne C; Poignard, Pascal; Burton, Dennis R; Zhu, Jiang

2014-01-01

162

Analysis of photometric spectra of 17 meteors  

NASA Technical Reports Server (NTRS)

The initial phase of the photometry which involved 17 meteor spectra consisting of eight Geminid spectra, six Orionid spectra and three Eta Aquarid spectra is discussed. Among these 17 spectra it is found that the Geminid spectra are of the best quality and are used for the identification of the atomic lines and molecular bands that normally appear on video tape spectra. The data from the Geminid records are used for developing calibration techniques in photometry. The Orionid and Eta Aquarid spectra are chosen for early analysis because of the current interest in all physical and chemical data relating to Comet Halley.

Millman, P. M.

1982-01-01

163

Complex Spectra in Fusion Plasmas  

NASA Astrophysics Data System (ADS)

The need for quantitative evaluation of complex line emission spectra as observed in hot fusion plasmas initiated a challenging development of sophisticated interpretation tools based on integrating advanced atomic modelling with detailed treatment of the plasma environment. The successful merging of the two worlds has led to routine diagnostic procedures which have contributed enormously to the understanding of underlying plasma processes and also to a wide acceptance of spectroscopy as a reliable diagnostic method. In this paper three characteristic types of spectra of current and continuing interest are presented. The first is that of medium/heavy species with many ionisation stages revealed in survey VUV and XUV spectra. Such species occur as control gases, as wall materials, as ablated heavy species and possible as layered wall dopants for monitoring erosion. The spectra are complex with line-like and quasi-continuum regions and are amenable to advanced `pattern recognition' methods. The second type is of few electron, highly ionised systems observed as line-of-sight integrated passive emission spectra in the soft x-ray region. They are analysed successfully in terms of plasma parameters through matching of observation with predicted synthetic spectra. Examples used here include highly resolved helium-like emission spectra of argon, iron and titanium observed on the tokamaks TEXTOR and Tore Supra. The third type, and the emphasis of this work, comprises spectra linked to active beam spectroscopy, that is, charge exchange recombination spectroscopy (CXRS) and beam emission spectroscopy (BES). In this case, a complex spectrum is again composed of a (usually) dominating active spectrum and an underlying passive emission spectrum. Its analysis requires modelling of both active and passive features. Examples used here are from the CXRS diagnostic at JET and TEXTOR. They display characteristic features of the main light impurity ions (C+6, He+2, N+7, Ne+10 and Ar+18), as well as that of the bulk plasma ions, H+, D+ and T+. A main conclusion is that spectral complexity is not necessarily negative, but that `complex structures' can provide a rich source of information on the plasma and its parameters—provided it is matched with integrated analysis—and that the methods can have universal applicability. In the present preparatory phase of the next generation fusion experiment ITER (International Thermonuclear Experimental Reactor) the concepts and expectations of complex spectra and integrated data analysis play an important role in the design and optimisation procedure of the ITER diagnostic assembly.

von Hellermann, M. G.; Bertschinger, G.; Biel, W.; Giroud, C.; Jaspers, R.; Jupen, C.; Marchuk, O.; O'Mullane, M.; Summers, H. P.; Whiteford, A.; Zastrow, K.-D.

2005-01-01

164

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

165

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

166

Separation of small metabolites and lipids in spectra from biopsies by diffusion-weighted HR-MAS NMR: a feasibility study.  

PubMed

High Resolution Magic Angle Spinning (HR-MAS) NMR allows metabolic characterization of biopsies. HR-MAS spectra from tissues of most organs show strong lipid contributions that are overlapping metabolite regions, which hamper metabolite estimation. Metabolite quantification and analysis would benefit from a separation of lipids and small metabolites. Generally, a relaxation filter is used to reduce lipid contributions. However, the strong relaxation filter required to eliminate most of the lipids also reduces the signals for small metabolites. The aim of our study was therefore to investigate different diffusion editing techniques in order to employ diffusion differences for separating lipid and small metabolite contributions in the spectra from different organs for unbiased metabonomic analysis. Thus, 1D and 2D diffusion measurements were performed, and pure lipid spectra that were obtained at strong diffusion weighting (DW) were subtracted from those obtained at low DW, which include both small metabolites and lipids. This subtraction yielded almost lipid free small metabolite spectra from muscle tissue. Further improved separation was obtained by combining a 1D diffusion sequence with a T2-filter, with the subtraction method eliminating residual lipids from the spectra. Similar results obtained for biopsies of different organs suggest that this method is applicable in various tissue types. The elimination of lipids from HR-MAS spectra and the resulting less biased assessment of small metabolites have potential to remove ambiguities in the interpretation of metabonomic results. This is demonstrated in a reproducibility study on biopsies from human muscle. PMID:25368873

Diserens, G; Vermathen, M; Precht, C; Broskey, N T; Boesch, C; Amati, F; Dufour, J-F; Vermathen, P

2015-01-01

167

SPECTRA/SCAMP Application Packet  

E-print Network

for the summer and fall semesters. Students interested in becoming an intern must complete the general during the Summer II session as it will interfere with your duties as an Intern. Also, Interns2014 SPECTRA/SCAMP Intern Application Packet DEADLINE FOR COMPLETED APPLICATIONS: Wednesday

Young, Paul Thomas

168

cloud supersaturations and CCN spectra  

NASA Astrophysics Data System (ADS)

Multiple regression analysis predictions of low altitude cloud droplet concentrations based on measured CCN spectra compared much better with measured low altitude droplet concentrations than various CCN concentrations at single supersaturations (S) in two aircraft cumulus cloud projects, RICO and ICE-T. The addition of vertical velocity (W) to the single and multiple regressions showed small improvements. For RICO the multiple regression correlations were also superior to previous adiabatic model predictions of droplet concentrations also based on CCN spectra and mean W. More adiabatic cloud parcels showed only slightly better correlations than flight-averaged droplet concentrations. Results show the value of more extensive CCN spectra and the relative unimportance of W variations for determining droplet concentrations in these Caribbean cumuli. The fact that flight-averaged droplet concentrations of all low cloud data was almost as well correlated with CCN spectra as were droplet concentrations of more adiabatic cloud parcels indicates that entrainment did not significantly perturb CCN-droplet concentration relationships. As should be expected higher cloud S were determined for the cumulus clouds than for stratus clouds. Suppression of cloud S by higher CCN concentrations that had previously been observed in stratus was observed in ICE-T but not in RICO where the CCN range may have been too low for cloud S suppression. But ICE-T and a stratus project, POST, even showed this S suppression over the same limited maritime CCN range as RICO.

Hudson, James; Noble, Stephen

2014-05-01

169

The LickX spectra  

NASA Astrophysics Data System (ADS)

Context. Collections of stellar spectra, often called stellar libraries, are useful in a variety of applications in the field of stellar populations. Aims: This is an attempt to improve the much-used Lick library of stellar spectra by removing jitter from the wavelength scale via cross-correlation, and calling the result the LickX library. Methods: Each spectrum was cross-correlated with a template spectrum and a new wavelength solution sought. Low-order polynomials were fit to adjust the old scale to a new fit. Indices were measured, new standard star averages found, and adjusted averages derived for the program stars. Results: The greatest gains in accuracy are expected for the fainter stars and stars of extreme surface temperatures; the bright K giant standard stars in LickX have the same uncertainties as Lick. The spectra and a table of index measurements in which repeated measurements are averaged are made available electronically. Individual stellar spectra, in FITS files, and the ascii catalog of absorption feature index strengths are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/561/A36

Worthey, G.; Danilet, A. B.; Faber, S. M.

2014-01-01

170

Classical Trajectories and Quantum Spectra  

NASA Technical Reports Server (NTRS)

A classical model of the Schrodinger's wave packet is considered. The problem of finding the energy levels corresponds to a classical manipulation game. It leads to an approximate but non-perturbative method of finding the eigenvalues, exploring the bifurcations of classical trajectories. The role of squeezing turns out decisive in the generation of the discrete spectra.

Mielnik, Bogdan; Reyes, Marco A.

1996-01-01

171

Unbiased screen for interactors of leucine-rich repeat kinase 2 supports a common pathway for sporadic and familial Parkinson disease.  

PubMed

Mutations in leucine-rich repeat kinase 2 (LRRK2) cause inherited Parkinson disease (PD), and common variants around LRRK2 are a risk factor for sporadic PD. Using protein-protein interaction arrays, we identified BCL2-associated athanogene 5, Rab7L1 (RAB7, member RAS oncogene family-like 1), and Cyclin-G-associated kinase as binding partners of LRRK2. The latter two genes are candidate genes for risk for sporadic PD identified by genome-wide association studies. These proteins form a complex that promotes clearance of Golgi-derived vesicles through the autophagy-lysosome system both in vitro and in vivo. We propose that three different genes for PD have a common biological function. More generally, data integration from multiple unbiased screens can provide insight into human disease mechanisms. PMID:24510904

Beilina, Alexandria; Rudenko, Iakov N; Kaganovich, Alice; Civiero, Laura; Chau, Hien; Kalia, Suneil K; Kalia, Lorraine V; Lobbestael, Evy; Chia, Ruth; Ndukwe, Kelechi; Ding, Jinhui; Nalls, Mike A; Olszewski, Maciej; Hauser, David N; Kumaran, Ravindran; Lozano, Andres M; Baekelandt, Veerle; Greene, Lois E; Taymans, Jean-Marc; Greggio, Elisa; Cookson, Mark R

2014-02-18

172

Unbiased screen for interactors of leucine-rich repeat kinase 2 supports a common pathway for sporadic and familial Parkinson disease  

PubMed Central

Mutations in leucine-rich repeat kinase 2 (LRRK2) cause inherited Parkinson disease (PD), and common variants around LRRK2 are a risk factor for sporadic PD. Using protein–protein interaction arrays, we identified BCL2-associated athanogene 5, Rab7L1 (RAB7, member RAS oncogene family-like 1), and Cyclin-G–associated kinase as binding partners of LRRK2. The latter two genes are candidate genes for risk for sporadic PD identified by genome-wide association studies. These proteins form a complex that promotes clearance of Golgi-derived vesicles through the autophagy–lysosome system both in vitro and in vivo. We propose that three different genes for PD have a common biological function. More generally, data integration from multiple unbiased screens can provide insight into human disease mechanisms. PMID:24510904

Beilina, Alexandria; Rudenko, Iakov N.; Kaganovich, Alice; Civiero, Laura; Chau, Hien; Kalia, Suneil K.; Kalia, Lorraine V.; Lobbestael, Evy; Chia, Ruth; Ndukwe, Kelechi; Ding, Jinhui; Nalls, Mike A.; Olszewski, Maciej; Hauser, David N.; Kumaran, Ravindran; Lozano, Andres M.; Baekelandt, Veerle; Greene, Lois E.; Taymans, Jean-Marc; Greggio, Elisa; Cookson, Mark R.; Nalls, Mike A.; Plagnol, Vincent; Martinez, Maria; Hernandez, Dena G; Sharma, Manu; Sheerin, Una-Marie; Saad, Mohamad; Simón-Sánchez, Javier; Schulte, Claudia; Lesage, Suzanne; Sveinbjörnsdóttir, Sigurlaug; Arepalli, Sampath; Barker, Roger; Ben-Shlomo, Yoav; Berendse, Henk W; Berg, Daniela; Bhatia, Kailash; de Bie, Rob M A; Biffi, Alessandro; Bloem, Bas; Bochdanovits, Zoltan; Bonin, Michael; Bras, Jose M; Brockmann, Kathrin; Brooks, Janet; Burn, David J; Charlesworth, Gavin; Chen, Honglei; Chong, Sean; Clarke, Carl E; Cookson, Mark R; Cooper, J Mark; Corvol, Jean Christophe; Counsell, Carl; Damier, Philippe; Dartigues, Jean-François; Deloukas, Panos; Deuschl, Günther; Dexter, David T; van Dijk, Karin D; Dillman, Allissa; Durif, Frank; Dürr, Alexandra; Edkins, Sarah; Evans, Jonathan R; Foltynie, Thomas; Gao, Jianjun; Gardner, Michelle; Gibbs, J Raphael; Goate, Alison; Gray, Emma; Guerreiro, Rita; Gústafsson, Ómar; Harris, Clare; van Hilten, Jacobus J; Hofman, Albert; Hollenbeck, Albert; Holton, Janice; Hu, Michele; Huang, Xuemei; Huber, Heiko; Hudson, Gavin; Hunt, Sarah E; Huttenlocher, Johanna; Illig, Thomas; München, Helmholtz Zentrum; Jónsson, Pálmi V; Lambert, Jean-Charles; Langford, Cordelia; Lees, Andrew; Lichtner, Peter; München, Helmholtz Zentrum; Limousin, Patricia; Lopez, Grisel; Lorenz, Delia; McNeill, Alisdair; Moorby, Catriona; Moore, Matthew; Morris, Huw R; Morrison, Karen E; Mudanohwo, Ese; O’Sullivan, Sean S; Pearson, Justin; Perlmutter, Joel S; Pétursson, Hjörvar; Pollak, Pierre; Post, Bart; Potter, Simon; Ravina, Bernard; Revesz, Tamas; Riess, Olaf; Rivadeneira, Fernando; Rizzu, Patrizia; Ryten, Mina; Sawcer, Stephen; Schapira, Anthony; Scheffer, Hans; Shaw, Karen; Shoulson, Ira; Sidransky, Ellen; Smith, Colin; Spencer, Chris C A; Stefánsson, Hreinn; Steinberg, Stacy; Stockton, Joanna D; Strange, Amy; Talbot, Kevin; Tanner, Carlie M; Tashakkori-Ghanbaria, Avazeh; Tison, François; Trabzuni, Daniah; Traynor, Bryan J; Uitterlinden, André G; Velseboer, Daan; Vidailhet, Marie; Walker, Robert; van de Warrenburg, Bart; Wickremaratchi, Mirdhu; Williams, Nigel; Williams-Gray, Caroline H; Winder-Rhodes, Sophie; Stefánsson, Kári; Hardy, John; Heutink, Peter; Brice, Alexis; Gasser, Thomas; Singleton, Andrew B; Wood, Nicholas W; Chinnery, Patrick F; Arepalli, Sampath; Cookson, Mark R; Dillman, Allissa; Ferrucci, Luigi; Gibbs, J Raphael; Hernandez, Dena G; Johnson, Robert; Longo, Dan L; Majounie, Elisa; Nalls, Michael A; O’Brien, Richard; Singleton, Andrew B; Traynor, Bryan J; Troncoso, Juan; van der Brug, Marcel; Zielke, H Ronald; Zonderman, Alan B

2014-01-01

173

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. PMID:23913641

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

2013-10-15

174

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

175

Wave envelope and related spectra  

SciTech Connect

Theoretical forms of spectra associated with the odd and even powers of the wave envelope are examined. It is shown that spectral densities for the even powers of the envelope admit exact forms, whereas those for the odd powers can only be expressed in series, involving first-, second-, and higher-order terms. The implications of these results are discussed and contrasted with a number of similar results stated in previous studies. Certain discrepancies and points of concern encountered are clarified. The two leading terms to the envelope spectral density are then examined in detail and compared with simulated data typical of wide- and narrow-banded waves. It is found that the sum of these two leading terms would represent the envelope spectral density with sufficient accuracy for most purposes. As an alternative to the relatively complex analytical forms implied by envelope-related spectra, the possibility of constructing more practical approximations is considered.

Tayfun, A. (College of Engineering Petroleum, Kuwait Univ., Safat (KW)); Lo, J.M. (Kuwait Inst. of Scientific Research (Kuwait))

1989-07-01

176

Automatic Classification of Stellar Spectra  

NASA Astrophysics Data System (ADS)

We propose and discuss the application of artificial intelligence techniques to the classification of stellar spectra. Two types of systems are considered, knowledge-based systems (Expert Systems) and different classes of neural networks. After analysing and comparing the performance of both systems in the classification of stellar spectra, we reach the conclusion that neural networks are more adequate to determine the spectral types and luminosity of stars, whereas knowledge-based systems are more performative in determining global temperatures. In order to determine the best approach to the classification of each spectrum type, we describe and analyse the performance and results of various neural networks models. Backpropagation networks, self-organising maps and RBF networks in particular were designed and tested, through the implementation of different topologies, to obtain the global classification, spectral type and luminosity of stars. The best networks reached a success rate of approximately 97% for a sample of 100 testing spectra. The morphological analysis algorithms that were developed in the knowledge-based systems are used to extract and measure spectral features, and to obtain the input patterns of the neural networks. Some networks were trained with this parameterisation, others with flux values of specific spectral zones; it was the first strategy that resulted in a better performance. Our approach is focused on the integration of several techniques in a unique hybrid system. In particular, signal processing, expert systems, fuzzy logic and artificial neural networks are integrated by means of a relational database, which allows us to structure the collected astronomical data and to contrast the results of the different classification methods. In addition, we designed several models of artificial neural networks that were trained with synthetic spectra, and included them as an alternative classification method. The proposed system is capable of deciding the most appropriate classification method for each spectrum, which widely opens the research in the field of automatic classification.

Carricajo, I.; Manteiga, M.; Rodríguez, A.; Dafonte, C.

2004-09-01

177

Ultraviolet Spectra of Uranian Satellites  

NASA Astrophysics Data System (ADS)

The ultraviolet reflectance spectra of the icy satellites ofUranus are largely unknown. We propose to use the HubbleSpace Telescope Faint Object Spectrograph in order to obtainthe first high S/N UV spectra of Ariel, Titania, and Oberon.Because of our innovative targeting approach, we have alsobeen able to include Umbriel in our observational plans.These satellites sample almost the full range of UV albedosand UV/VIS colors exhibited by the large Uranian satellites.The spectral resolution and range will overlap with earth-based telescopic and spacecraft observations of these objectsallowing for comparisons of the UV data with existing visualand near-infrared spectra of these objects. These comparisonswill ultimately provide greater constraints on the relativelylow albedo spectrally neutral non-ice component on the Uraniansatellites. The existance of UV spectral features due tospecies such as O_3, H_2O_2 or carbon-rich macromolecules(e.g. polycyclic aromatic hydrocarbons) can provide evidencefor modification of the surfaces via plasma or meteoriticbombardment, alteration by high-energy ultraviolet radiation,or accretion of particles from nearby sources such asplanetary rings or dust bands.

Roush, Ted

1996-07-01

178

Reflection spectra of solids of planetary interest  

NASA Technical Reports Server (NTRS)

This paper reproduces the spectra of solids which might be found on the surfaces of planetary bodies or as solid condensates in the upper planetary atmosphere. Among these are spectra of various iron compounds of interest in the study of the clouds of Venus. Other spectra (some at low temperature) are included for various sulfides relevant to the planet Jupiter. Meteorite and coal spectra are also included to illustrate dark carbon compounds.

Sill, G. T.; Carm, O.

1973-01-01

179

Action spectra for photosynthetic inhibition  

NASA Technical Reports Server (NTRS)

The ultraviolet action spectrum for photosynthesis inhibition was determined to fall between that of the general DNA action spectrum and the generalized plant action spectrum. The characteristics of this action spectrum suggest that a combination of pronounced increase in effectiveness with decreasing wavelength, substantial specificity for the UV-B waveband, and very diminished response in the UV-A waveband result in large radiation amplification factors when the action spectra are used as weighting functions. Attempted determination of dose/response relationships for leaf disc inhibition provided inconclusive data from which to deconvolute an action spectrum.

Caldwell, M. M.; Flint, S.; Camp, L. B.

1981-01-01

180

Visible Spectra of Titanium Dioxide  

NASA Astrophysics Data System (ADS)

Titanium oxide (TiO) has been extensively studied spectroscopically due to its astrophysical relevance. TiO is the main opacity source in the atmospheres of cool M-type stars in the visible and near infrared. In view of the high cosmic abundance of Ti and O, titanium dioxide (TiO2) is believed to play an important role in dust formation processes from the gas-phase in circumstellar shells of oxygen-rich stars. The electronic spectra of a cold molecular beam of TiO2 have been investigated using mass-resolved resonance enhanced multi-photon ionization and laser induced fluorescence spectroscopy. TiO2 was produced by laser ablation of a pure titanium rod in the presence of a supersonic expanding mixture of approximately 5% O2 in either helium or argon. The spectra were recorded in the region 17500 cm-1 to 22500 cm-1 and the bands assigned to the A1B2 ? X1A1 transition. The origin and harmonic vibrational constants for the A1B2 state were determined to be: T000 = 17593(5) cm-1, ?1 = 876(3) cm-1, ?2 = 184(1) cm-1, and ?3 = 316(2) cm-1. Further, the dispersed fluorescence of a few bands were recorded to obtain vibrational parameters for the X1A1 state.

Gupta, V.; Nagarajan, R.; Maier, J. P.; Zhuang, X.; Le, A.; Steimle, T. C.

2011-05-01

181

Pressure spectra and cross spectra at an area contraction in a ducted combustion system  

NASA Technical Reports Server (NTRS)

Pressure spectra and cross-spectra at an area contraction in a liquid fuel, ducted, combustion noise test facility are analyzed. Measurements made over a range of air and fuel flows are discussed. Measured spectra are compared with spectra calculated using a simple analytical model.

Miles, J. H.; Raftopoulos, D. D.

1980-01-01

182

Vibrational Spectra of Chlorinated Poly  

NASA Astrophysics Data System (ADS)

In order to refine the force field for secondary chlorides which is applicable to chlorinated poly (vinyl chloride), CPVC, 2,3,4-trichloro-pentanes and 2,2,3-trichloro -butane were synthesized. To avoid trouble upon separation of a meso and racemic isomer mixture of 2,3,4-trichloro -pentanes, we used a new method to obtain each isomer exclusively. Each isomer was identified by NMR. However, to confirm the identification, one of the tosylates, which is a precursor to be converted to the meso form, was structurally determined by X-ray crystallography. The ir and Raman spectra were observed for both isomers of 2,3,4-trichloro-pentanes and 2,2,3-trichloro-butane at room temperature and in the crystalline states. The force constant refinement procedure was divided into two steps. In the first step, force constants related to adjacently chlorinated units such as -CHCl-CHCl-CHCl - were refined by using meso and racemic isomers of 2,3,4 -trichloro-pentanes, meso and racemic isomers of 2,4-dichloro -pentanes, and two trans isomers (MRSM, MRRM) of 2,3-dichloro -butanes. In the next step, the force constants related to CCl_2 were refined by using trans and gauche isomers of 2,2-dichloro-butane, 2,2-dichloro -propane, and trans, gauche and gauche (-) forms of 2,2,3-trichloro-butane. The final refined force constants are tabulated. To validate the transferability of the refined force constants, the normal frequencies were calculated for 2-chloro-butane, 3-chloro-pentane, and syndiotactic, isotactic, and heterotactic isomers of 2,4,6-trichloro-heptanes, as well as syndiotactic PVC. The calculated bands well matched the observed bands. In particular, C-Cl stretches, which are sensitive to the conformation, were predicted within 5 cm^{-1} . The ir and Raman spectra of PVC and CPVC for the five different chlorine contents, 57.70%, 61.48%, 63.34%, 67.92%, and 70.92% were observed. To elucidate these spectra, normal mode analyses (NMA) were conducted for tetrad PVC fragments (010101010), and for CPVC fragments such as (010111010), (011111010), (0102010), (0121010), (0121110), (010202010), and (010202110). (Numerical designation was used for the three carbons in CPVC: CH_2 = 0, CHCl = 1, CCl_2 = 2). According to the NMA, CH_2 groups of the center r unit of r-r-m, and m-r-m heterotactic PVC tetrads were chlorinated in the early stages of the reaction.

Chough, Sung Hyo

183

Particle infectivity of HIV-1 full-length genome infectious molecular clones in a subtype C heterosexual transmission pair following high fidelity amplification and unbiased cloning.  

PubMed

The high genetic diversity of HIV-1 impedes high throughput, large-scale sequencing and full-length genome cloning by common restriction enzyme based methods. Applying novel methods that employ a high-fidelity polymerase for amplification and an unbiased fusion-based cloning strategy, we have generated several HIV-1 full-length genome infectious molecular clones from an epidemiologically linked transmission pair. These clones represent the transmitted/founder virus and phylogenetically diverse non-transmitted variants from the chronically infected individual?s diverse quasispecies near the time of transmission. We demonstrate that, using this approach, PCR-induced mutations in full-length clones derived from their cognate single genome amplicons are rare. Furthermore, all eight non-transmitted genomes tested produced functional virus with a range of infectivities, belying the previous assumption that a majority of circulating viruses in chronic HIV-1 infection are defective. Thus, these methods provide important tools to update protocols in molecular biology that can be universally applied to the study of human viral pathogens. PMID:25243334

Deymier, Martin J; Claiborne, Daniel T; Ende, Zachary; Ratner, Hannah K; Kilembe, William; Allen, Susan; Hunter, Eric

2014-11-01

184

Coupling Unbiased Mutagenesis to High-throughput DNA Sequencing Uncovers Functional Domains in the Ndc80 Kinetochore Protein of Saccharomyces cerevisiae  

PubMed Central

During mitosis, kinetochores physically link chromosomes to the dynamic ends of spindle microtubules. This linkage depends on the Ndc80 complex, a conserved and essential microtubule-binding component of the kinetochore. As a member of the complex, the Ndc80 protein forms microtubule attachments through a calponin homology domain. Ndc80 is also required for recruiting other components to the kinetochore and responding to mitotic regulatory signals. While the calponin homology domain has been the focus of biochemical and structural characterization, the function of the remainder of Ndc80 is poorly understood. Here, we utilized a new approach that couples high-throughput sequencing to a saturating linker-scanning mutagenesis screen in Saccharomyces cerevisiae. We identified domains in previously uncharacterized regions of Ndc80 that are essential for its function in vivo. We show that a helical hairpin adjacent to the calponin homology domain influences microtubule binding by the complex. Furthermore, a mutation in this hairpin abolishes the ability of the Dam1 complex to strengthen microtubule attachments made by the Ndc80 complex. Finally, we defined a C-terminal segment of Ndc80 required for tetramerization of the Ndc80 complex in vivo. This unbiased mutagenesis approach can be generally applied to genes in S. cerevisiae to identify functional properties and domains. PMID:23833183

Tien, Jerry F.; Fong, Kimberly K.; Umbreit, Neil T.; Payen, Celia; Zelter, Alex; Asbury, Charles L.; Dunham, Maitreya J.; Davis, Trisha N.

2013-01-01

185

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

2008-06-30

186

Application of the ?2 principle and unbiased predictive risk estimator for determining the regularization parameter in 3-D focusing gravity inversion  

NASA Astrophysics Data System (ADS)

The ?2 principle and the unbiased predictive risk estimator are used to determine optimal regularization parameters in the context of 3-D focusing gravity inversion with the minimum support stabilizer. At each iteration of the focusing inversion the minimum support stabilizer is determined and then the fidelity term is updated using the standard form transformation. Solution of the resulting Tikhonov functional is found efficiently using the singular value decomposition of the transformed model matrix, which also provides for efficient determination of the updated regularization parameter each step. Experimental 3-D simulations using synthetic data of a dipping dike and a cube anomaly demonstrate that both parameter estimation techniques outperform the Morozov discrepancy principle for determining the regularization parameter. Smaller relative errors of the reconstructed models are obtained with fewer iterations. Data acquired over the Gotvand dam site in the south-west of Iran are used to validate use of the methods for inversion of practical data and provide good estimates of anomalous structures within the subsurface.

Vatankhah, Saeed; Ardestani, Vahid E.; Renaut, Rosemary A.

2015-01-01

187

Optimal Extraction of Echelle Spectra  

NASA Astrophysics Data System (ADS)

The extraction of the echelle spectra registered with a CCD detector represents a big challenge because of three reasons: (1) the pixel sampling is often close or worse then optimal, (2) spectral orders are curved and tilted with respect to the CCD rows (or columns) and (3) every pixel contains additional noise coming from various sources as illustrated in Figure 1. The main goal of an optimal extraction is to recover as much of the science signal while minimizing the contribution of the noise. Here we present the Slit Function Decomposition algorithm which replaces the summation in a sliding window with a reconstruction of the slit illumination profile. The reconstruction is formulated as an inverse problem solved by iterations and it is robust against most of the systematic problems including cosmic rays and cosmetic defects.

Piskunov, Nikolai

188

[Vibrational spectra of Corallium elatius].  

PubMed

Corallium elatius, which has unique color distribution characteristic, is the most important species of Taiwan precious corals. EPMA, XRD, FTIR and Laser Raman detective methods were used to study the chemical, mineral composition and spectra characteristics of Corallium elatius. The result of EPMA, XRD and FTIR shows the high-Mg calcite mineral componentand the stable minor chemical constituents of the samples. Meanwhile, the cell parameter indicates the lattice distortion and the preferred orientation of calcite grain caused by organic matter. The red part of the samples shows a different Raman spectrum from that of the white part, located at 1517/1128 cm(-1) and 1296/1016 cm(-1). Raman scattering measurement reveals the relationship between the organic matter and color. PMID:24369625

Fan, Lu-wei; Zhang, Yan; Hu, Yang

2013-09-01

189

Exploiting the full potential of photometric quasar surveys: optimal power spectra through blind mitigation of systematics  

NASA Astrophysics Data System (ADS)

We present optimal measurements of the angular power spectrum of the XDQSOz catalogue of photometric quasars from the Sloan Digital Sky Survey. These measurements rely on a quadratic maximum likelihood estimator that simultaneously measures the auto- and cross-power spectra of four redshift samples, and provides minimum-variance, unbiased estimates even at the largest angular scales. Since photometric quasars are known to be strongly affected by systematics such as spatially-varying depth and stellar contamination, we introduce a new framework of extended mode projection to robustly mitigate the impact of systematics on the power spectrum measurements. This technique involves constructing template maps of potential systematics, decorrelating them on the sky, and projecting out modes which are significantly correlated with the data. Our method is able to simultaneously process several thousands of non-linearly correlated systematics, and mode projection is performed in a blind fashion. Using our final power spectrum measurements, we find a good agreement with theoretical predictions, and no evidence for further contamination by systematics. Extended mode projection not only obviates the need for aggressive sky and quality cuts, but also provides control over the level of systematics in the measurements, enabling the search for small signals of new physics while avoiding confirmation bias.

Leistedt, Boris; Peiris, Hiranya V.

2014-10-01

190

Classification and Analysis of 30 Supernova Spectra  

NASA Astrophysics Data System (ADS)

I will present spectra of about 30 Supernovae (SNe) of various types, obtained in the course of the European Supernova Collaboration (ESC) Research Training Network (RTN). The classification of the objects has been performed using a SNe-specific automatic spectra classification tool that has been developed in the Padova observatory supernova group. These spectra are not published so far and the results of their detailed analysis are important components for our study of SNe physical properties.

Harutyunyan, Avet; et al.

2007-08-01

191

Reflection spectra of solids of planetary interest  

NASA Technical Reports Server (NTRS)

The spectra of solids are reproduced which might be found on the surfaces of planetary bodies or as solid condensates in the upper planetary atmosphere. Among these are spectra of various iron compounds of interest in the study of the clouds of Venus. Other spectra are included of various sulfides, some at low temperature, relevant to the planet Jupiter. Meteorite and coal abstracts are also included, to illustrate dark carbon compounds.

Sill, G. T.

1973-01-01

192

Near-Infrared Spectra of Uranian Satellites  

NASA Astrophysics Data System (ADS)

We present 0.8 to 2.5 micron spectra taken on June 21 & 22, 1998 UT of the Uranian satellites Miranda, Titania, Ariel, Oberon, and Umbriel. The spectra were taken using The Aerospace Corporation's Near-Infrared Imaging Spectragraph (NIRIS) on the University of California's Lick Observatory 3 meter Shane telescope. These spectra will be compared with previous work including Brown, R.H. and Cruikshank, D.P. (1983) as well as more recent spectra and analysis by Grundy, W. et al. (1999). Support for this research was provided by The Aerospace Corporation's Independent Research and Development Program.

Venturini, C. C.; Lynch, D. K.; Rudy, R. J.; Mazuk, S.; Puetter, R. C.

2001-05-01

193

Spectra of intracellular Fura-2.  

PubMed

In the theory of measurement of calcium ion activity by determination of Fura-2 fluorescence at two excitation wavelengths, the accuracy of the result depends upon the accuracy both of the sample measurements and of the calibration measurements which are made on calcium-bound and free dye. Two factors underlie adequate calibration and accuracy. The first is the elimination of systematic error due to spectral shifts arising from the intracellular environment felt by the dye. To this end, detailed comparisons between complete spectra of both calcium-bound and calcium-free Fura-2 can be used to help separate spectral effects due to light absorption by cellular constituents versus polarity and viscosity of the intracellular milieu. The second major factor which determines accuracy is the experimental uncertainty (in both sample and calibration measurements). For samples in which the ratio of bound to free dye is large, the uncertainty in the ratio is also large, even when it is expressed as a percentage of the ratio itself. The errors in calibration measurements impact on the accuracy of the method primarily through the measurements made at wavelengths which are off the spectral peaks of the bound or free dye, since these are the least accurate. In order to obtain a guide to the choice of wavelengths and estimation of the reliability of results, a mathematical expression is derived for the dependence of the accuracy of the method on the accuracy of both sample and calibration measurements. PMID:1715814

Owen, C S

1991-06-01

194

An unbiased resource of novel SNP markers provides a new chronology for the human Y chromosome and reveals a deep phylogenetic structure in Africa  

PubMed Central

Sequence diversity and the ages of the deepest nodes of the MSY phylogeny remain largely unexplored due to the severely biased collection of SNPs available for study. We characterized 68 worldwide Y chromosomes by high-coverage next-generation sequencing, including 18 deep-rooting ones, and identified 2386 SNPs, 80% of which were novel. Many aspects of this pool of variants resembled the pattern observed among genome-wide de novo events, suggesting that in the MSY, a large proportion of newly arisen alleles has survived in the phylogeny. Some degree of purifying selection emerged in the form of an excess of private missense variants. Our tree recapitulated the previously known topology, but the relative lengths of major branches were drastically modified and the associated node ages were remarkably older. We found significantly different branch lengths when comparing the rare deep-rooted A1b African lineage with the rest of the tree. Our dating results and phylogeography led to the following main conclusions: (1) Patrilineal lineages with ages approaching those of early AMH fossils survive today only in central-western Africa; (2) only a few evolutionarily successful MSY lineages survived between 160 and 115 kya; and (3) an early exit out of Africa (before 70 kya), which fits recent western Asian archaeological evidence, should be considered. Our experimental design produced an unbiased resource of new MSY markers informative for the initial formation of the anatomically modern human gene pool, i.e., a period of our evolution that had been previously considered to be poorly accessible with paternally inherited markers. PMID:24395829

Scozzari, Rosaria; Massaia, Andrea; Trombetta, Beniamino; Bellusci, Giovanna; Myres, Natalie M.; Novelletto, Andrea; Cruciani, Fulvio

2014-01-01

195

THE OPTICALLY UNBIASED GRB HOST (TOUGH) SURVEY. V. VLT/X-SHOOTER EMISSION-LINE REDSHIFTS FOR SWIFT GRBs AT z {approx} 2  

SciTech Connect

We present simultaneous optical and near-infrared (NIR) spectroscopy of 19 Swift {gamma}-ray burst (GRB) host galaxies observed with the VLT/X-shooter with the aim of measuring their redshifts. Galaxies were selected from The Optically Unbiased GRB Host (TOUGH) survey (15 of the 19 galaxies) or because they hosted GRBs without a bright optical afterglow. Here we provide emission-line redshifts for 13 of the observed galaxies with brightnesses between F606W > 27 mag and R = 22.9 mag (median R-tilde =24.6 mag). The median redshift is z-tilde =2.1 for all hosts and z-tilde =2.3 for the TOUGH hosts. Our new data significantly improve the redshift completeness of the TOUGH survey, which now stands at 77% (53 out of 69 GRBs). They furthermore provide accurate redshifts for nine prototype dark GRBs (e.g., GRB 071021 at z = 2.452 and GRB 080207 at z = 2.086), which are exemplary of GRBs where redshifts are challenging to obtain via afterglow spectroscopy. This establishes X-shooter spectroscopy as an efficient tool for redshift determination of faint, star-forming, high-redshift galaxies such as GRB hosts. It is hence a further step toward removing the bias in GRB samples that is caused by optically dark events, and provides the basis for a better understanding of the conditions in which GRBs form. The distribution of column densities as measured from X-ray data (N{sub H,X}), for example, is closely related to the darkness of the afterglow and skewed toward low N{sub H,X} values in samples that are dominated by bursts with bright optical afterglows.

Kruehler, Thomas; Malesani, Daniele; Milvang-Jensen, Bo; Fynbo, Johan P. U.; Hjorth, Jens; Sparre, Martin; Watson, Darach J. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Jakobsson, Pall [Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, 107 Reykjavik (Iceland); Levan, Andrew J. [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Tanvir, Nial R. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH (United Kingdom)

2012-10-10

196

Cancer net survival on registry data: use of the new unbiased Pohar-Perme estimator and magnitude of the bias with the classical methods.  

PubMed

Net survival, the survival which might occur if cancer was the only cause of death, is a major epidemiological indicator required for international or temporal comparisons. Recent findings have shown that all classical methods used for routine estimation of net survival from cancer-registry data, sometimes called "relative-survival methods," provide biased estimates. Meanwhile, an unbiased estimator, the Pohar-Perme estimator (PPE), was recently proposed. Using real data, we investigated the magnitude of the errors made by four "relative-survival" methods (Ederer I, Hakulinen, Ederer II and a univariable regression model) vs. PPE as reference and examined the influence of time of follow-up, cancer prognosis, and age on the errors made. The data concerned seven cancer sites (2,51,316 cases) collected by FRANCIM cancer registries. Net survivals were estimated at 5, 10 and 15 years postdiagnosis. At 5 years, the errors were generally small. At 10 years, in good-prognosis cancers, the errors made in nonstandardized estimates with all classical methods were generally great (+2.7 to +9% points in prostate cancer) and increased in age-class estimations (vs. 5-year ones). At 15 years, in bad- or average-prognosis cancers, the errors were often substantial whatever the nature of the estimation. In good-prognosis cancers, the errors in nonstandardized estimates of all classical methods were great and sometimes very important. With all classical methods, great errors occurred in age-class estimates resulting in errors in age-standardized estimates (+0.4 to +3.2% points in breast cancer). In estimating net survival, cancer registries should abandon all classical methods and adopt the new Pohar-Perme estimator. PMID:22961565

Roche, Laurent; Danieli, Coraline; Belot, Aurélien; Grosclaude, Pascale; Bouvier, Anne-Marie; Velten, Michel; Iwaz, Jean; Remontet, Laurent; Bossard, Nadine

2013-05-15

197

Faster optical-spectra recording and analysis  

NASA Technical Reports Server (NTRS)

Optical spectra are recorded and rapidly analyzed by system that links multichannel analyzer and desk-top programable calculator. Cassette-memory storage is provided. System can be programed to automate background subtraction, axis expansion, and other data-analysis techniques and can store several hundred spectra for immediate or delayed analysis and comparisons.

Richmond, R. G.

1977-01-01

198

Spectra of Quarkonia at Finite Temperature  

E-print Network

Finite-temperature spectra of heavy quarkonia are calculated by combining potential model and thermofield dynamics formalisms. The mass spectra of the heavy quarkonia with various quark contents are calculated. It is found that binding mass of the quarkonium decreases as temperature increases.

D. U. Matrasulov; F. C. Khanna; Kh. T. Butanov; Kh. Yu. Rakhimov

2006-06-02

199

Atomic Models and X-Ray Spectra  

Microsoft Academic Search

IN his letter to NATURE of January 1 on ``Atomic Models and X-Ray Spectra,'' Dr. F. A. Lindemann deals with the approximate agreement between the recent experiments of Mr. H. G. J. Moseley on ``The High-frequency Spectra of the Elements'' (Phil. Mag., December, 1913), and the calculations given in my paper, ``On the Constitution of Atoms and Molecules'' (Phil. Mag.,

N. Bohr

1914-01-01

200

DYNAMIC SPECTRA OF JUPITER'S DECAMETRIC EMISSION, 1961  

Microsoft Academic Search

Sources for the decametric emission from Jupiter are suggested and ; evidence for their existence presented. Dynamic spectra for negative and ; positive drift emission and composite spectra are displayed and discussed. An ; explanation of the emission based on Jupiter's possession of energetic radiation ; belts similar to earth's is presented. (D.C.W.);

James W. Warwick

1963-01-01

201

Spectra and pseudospectra for pipe Poiseuille flow  

Microsoft Academic Search

Numerically computed spectra and pseudospectra are presented for the linear operator that governs the temporal evolution of infinitesimal perturbations of laminar flow in an infinite circular pipe at Reynolds numbers 1000, 3000 and 10 000. The spectra lie strictly inside the stable complex half-plane, but the pseudospectra protrude significantly into the unstable half-plane, reflecting the large linear transient growth that

Anne E. Trefethen; Lloyd N. Trefethen; Peter J. Schmid

1994-01-01

202

Polarized electroabsorption spectra of amorphous semiconductors  

Microsoft Academic Search

Transverse electroabsorption spectra of amorphous Se and hydrogenated amorphous Si (a-Si: H) are presented. These spectra are anisotropic, with fields F parallel to the polarization E of light, causing much larger signals than F perpendicular to E. At temperatures below 350 K the signal depends little on temperature. At higher temperatures the field-induced change ?? in the absorption increases in

G. Weiser; U. Dersch; P. Thomas

1988-01-01

203

Nonmesonic Weak Decay Spectra of Light Hypernuclei  

NASA Astrophysics Data System (ADS)

The nonmesonic weak decay spectra of light hypernuclei have been evaluated in a systematic way. As theoretical framework we adopt the independent particle shell model with three different one-meson-exchange transition potentials. Good agreement with data is obtained for proton and neutron kinetic energy spectra of He, and He, when the recoil effect is considered. The coincidence spectra of proton-neutron pairs are also accounted for quite reasonably, but it was not possible to reproduce the data for the neutron-neutron pair spectra. It is suggested that the ? + K meson-exchange model with soft monopole form factors could be a good starting point for describing the dynamics responsible for the decays of these two hypernuclei. The H spectra are also presented.

Krmpoti?, Franjo

2014-04-01

204

Nonmesonic weak decay spectra of light hypernuclei  

E-print Network

The nonmesonic weak decay spectra of light hypernuclei have been evaluated in a systematic way. As theoretical framework we adopt the independent particle shell model with three different one-meson-exchange transition potentials. Good agreement with data is obtained for proton and neutron kinetic energy spectra of $^4_\\Lambda$He, and $^5_\\Lambda$He, when the recoil effect is considered. The coincidence spectra of proton-neutron pairs are also accounted for quite reasonably, but it was not possible to reproduce the data for the neutron-neutron pair spectra. It is suggested that the $\\pi+K$ meson-exchange model with soft monopole form factors could be a good starting point for describing the dynamics responsible for the decays of these two hypernuclei. The $^4_\\Lambda$H~ spectra are also presented.

Krmpoti?, Franjo

2014-01-01

205

Nonmesonic weak decay spectra of light hypernuclei  

E-print Network

The nonmesonic weak decay spectra of light hypernuclei have been evaluated in a systematic way. As theoretical framework we adopt the independent particle shell model with three different one-meson-exchange transition potentials. Good agreement with data is obtained for proton and neutron kinetic energy spectra of $^4_\\Lambda$He, and $^5_\\Lambda$He, when the recoil effect is considered. The coincidence spectra of proton-neutron pairs are also accounted for quite reasonably, but it was not possible to reproduce the data for the neutron-neutron pair spectra. It is suggested that the $\\pi+K$ meson-exchange model with soft monopole form factors could be a good starting point for describing the dynamics responsible for the decays of these two hypernuclei. The $^4_\\Lambda$H~ spectra are also presented.

Franjo Krmpoti?

2014-07-17

206

The Historical Spectra of ? Car, 1892 -- 1941  

NASA Astrophysics Data System (ADS)

The Harvard objective prism spectra of ? Car cover the period from 1892 to 1941. The famous spectra from 1892 and 1893 were the first recorded spectra of ? Car and are especially significant because they caught the star during its second or lesser eruption when it had the spectrum of an F -- type supergiant. Visual inspection and digitized scans of the spectra from 1892 to ˜ 1920 confirm the conclusion by Feast, Whitelock and Marang(2001) that there were no high excitation lines, specifically He I ? 4471, in the spectrum during this time. The Harvard plates have very good coverage from 1922 to 1926 and from 1937 to 1941. Our visual inspection combined with measurements of the digitized scans, show no evidence of high excitation lines Figure 1 shows one of the best spectra and the region where He I 4471 is expected. A line at ? 4474 is easily misidentified with He I, but is a blend of Fe II and [Fe II] lines. Feast, Whitelock and Marang(2001) made the same identification. Thus, the star's spectrum was always in the low excitation state from 1892 to 1941. There is no spectroscopic evidence for the presence of the He I line or other high excitation emission lines in the spectra until Gaviola(1953) obtained his first spectra (1944- 1951) showing He I emission, and no 5.5 year cycle as we understand it today.

Humphreys, R. M.; Koppelman, M.

2005-09-01

207

3 - 13 ?m Spectra of Geosynchronous Satellites  

NASA Astrophysics Data System (ADS)

We report 3-13 ?m spectra of three geosynchronous satellites using The Aerospace Corporation's Broadband Array Spectrograph System (BASS) on the AEOS 3.7 meter telescope at Haleakala in December 2005. The satellites observed were NORAD 21639 (TDRS 5), 11145 (DSCS 2-12) and 15629 (INTELSAT 510). The spectra showed structure indicative of the satellites' surface material, temperature and cross section as viewed from the observatory. A brief summery of how to analyze such spectra to retrieve surface material composition, temperature and geometrical cross section is included.

Lynch, D.; Russell, R.; Rudy, R.; Gutierrez, D.; Turpin, M.; Crawford, K.; Dotan, Y.; Kim, D.; Skinner, M.

208

Analysis of atmospheric spectra for trace gases  

NASA Technical Reports Server (NTRS)

The objective is the comprehensive analysis of high resolution atmospheric spectra recorded in the middle-infrared region to obtain simultaneous measurements of coupled parameters (gas concentrations of key trace constituents, total column amounts, pressure, and temperature) in the stratosphere and upper troposphere. Solar absorption spectra recorded at 0.002 and 0.02 cm exp -1 resolutions with the University of Denver group's balloon-borne, aircraft borne, and ground-based interferometers and 0.005 to 0.01 cm exp -1 resolution solar spectra from Kitt Peak are used in the analyses.

Rinsland, Curtis P.; Seals, Robert K., Jr.; Smith, Mary Ann H.; Goldman, Aaron; Murcray, David G.; Murcray, Frank J.

1990-01-01

209

THE OPTICALLY UNBIASED GRB HOST (TOUGH) SURVEY. VI. RADIO OBSERVATIONS AT z {approx}< 1 AND CONSISTENCY WITH TYPICAL STAR-FORMING GALAXIES  

SciTech Connect

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 {approx}825 M{sub Sun} yr{sup -1}, the highest ever reported for a GRB host, places it in the category of ultraluminous infrared galaxies. We found that at least {approx}63% of GRB hosts have SFR < 100 M{sub Sun} yr{sup -1} and at most {approx}8% can have SFR > 500 M{sub Sun} yr{sup -1}. For the undetected hosts the mean radio flux (<35 {mu}Jy 3{sigma}) corresponds to an average SFR < 15 M{sub Sun} yr{sup -1}. Moreover, {approx}> 88% of the z {approx}< 1 GRB hosts have ultraviolet dust attenuation A{sub UV} < 6.7 mag (visual attenuation A{sub V} < 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{sub UV} of GRB hosts are consistent with those of Lyman break galaxies, H{alpha} 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 {approx}< 1, trace a large fraction of all star formation, and are therefore less biased indicators than once thought.

Michalowski, M. J.; Dunlop, J. S. [SUPA (Scottish Universities Physics Alliance), Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ (United Kingdom); Kamble, A.; Kaplan, D. L. [Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211 (United States); Hjorth, J.; Malesani, D.; Fynbo, J. P. U.; Kruehler, T. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen O (Denmark); Reinfrank, R. F. [CSIRO Astronomy and Space Science, P.O. Box 76, Epping, NSW 1710 (Australia); Bonavera, L. [Instituto de Fisica de Cantabria, CSIC-Universidad de Cantabria, Avda. de los Castros s/n, E-39005 Santander (Spain); Castro Ceron, J. M. [Department of Radio Astronomy, Madrid Deep Space Communications Complex (INTA-NASA/INSA), Ctra. M-531, km. 7, E-28.294 Robledo de Chavela (Madrid) (Spain); Ibar, E. [UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Garrett, M. A. [Netherlands Institute for Radio Astronomy (ASTRON), Postbus 2, 7990 AA Dwingeloo (Netherlands); Jakobsson, P. [Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, 107 Reykjavik (Iceland); Levan, A. J. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Massardi, M. [INAF-Istituto di Radioastronomia, via Gobetti 101, I-40129 Bologna (Italy); Pal, S. [ICRAR, University of Western Australia, 35 Stirling Highway, Crawley, WA (Australia); Sollerman, J. [Oskar Klein Centre, Department of Astronomy, AlbaNova, Stockholm University, SE-10691 Stockholm (Sweden); Tanvir, N. R. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Van der Horst, A. J., E-mail: mm@roe.ac.uk [Astronomical Institute 'Anton Pannekoek', University of Amsterdam, Science Park 904, 1098XH Amsterdam (Netherlands); and others

2012-08-20

210

Seismic source spectra and estimated stress drop derived from cohesive-zone models of circular subshear rupture  

NASA Astrophysics Data System (ADS)

Earthquake stress drops are often estimated from far-field body wave spectra using measurements of seismic moment, corner frequency and a specific theoretical model of rupture behaviour. The most widely used model is from Madariaga in 1976, who performed finite-difference calculations for a singular crack radially expanding at a constant speed and showed that bar{f}_c = k ? /a, where bar{f}_c is spherically averaged corner frequency, ? is the shear wave speed, a is the radius of the circular source and k = 0.32 and 0.21 for P and S waves, respectively, assuming the rupture speed Vr = 0.9?. Since stress in the Madariaga model is singular at the rupture front, the finite mesh size and smoothing procedures may have affected the resulting corner frequencies. Here, we investigate the behaviour of source spectra derived from dynamic models of a radially expanding rupture on a circular fault with a cohesive zone that prevents a stress singularity at the rupture front. We find that in the small-scale yielding limit where the cohesive-zone size becomes much smaller than the source dimension, P- and S-wave corner frequencies of far-field body wave spectra are systematically larger than those predicted by the Madariaga model. In particular, the model with rupture speed Vr = 0.9? shows that k = 0.38 for P waves and k = 0.26 for S waves, which are 19 and 24 per cent larger, respectively, than those of Madariaga. Thus for these ruptures, the application of the Madariaga model overestimates stress drops by a factor of 1.7. In addition, the large dependence of corner frequency on take-off angle relative to the source suggests that measurements from a small number of seismic stations are unlikely to produce unbiased estimates of spherically averaged corner frequency.

Kaneko, Y.; Shearer, P. M.

2014-05-01

211

Comparing Ultraviolet Spectra Against Calculations: First Results  

NASA Technical Reports Server (NTRS)

The five-year goal of this effort is to calculate high fidelity mid-UV spectra for individual stars and stellar systems for a wide range of ages, abundances, and abundance ratios. In this first year, the emphasis was placed on revising the list of atomic line parameters used to calculate mid-UV spectra. First, new identifications of atomic lines and measurements of their transition probabilities were obtained for lines of the first and second ionization stages of iron-peak elements. Second, observed mid-UV and optical spectra for standard stars were re-analyzed and compared to new calculations, to refine the determination of transition probabilities and to estimate the identity of lines still missing from the laboratory lists. As evidenced by the figures, a dramatic improvement has resulted in the reproduction of the spectra of standard stars by the calculations.

Peterson, Ruth C.

2003-01-01

212

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

213

Microwave spectra of some volatile organic compounds  

NASA Technical Reports Server (NTRS)

A computer-controlled microwave (MRR) spectrometer was used to catalog reference spectra for chemical analysis. Tables of absorption frequency, peak absorption intensity, and integrated intensity are included for 26 volatile organic compounds, all but one of which contain oxygen.

White, W. F.

1975-01-01

214

Improved peak shape fitting in alpha spectra.  

PubMed

Peak overlap is a recurrent issue in alpha-particle spectrometry, not only in routine analyses but also in the high-resolution spectra from which reference values for alpha emission probabilities are derived. In this work, improved peak shape formulae are presented for the deconvolution of alpha-particle spectra. They have been implemented as fit functions in a spreadsheet application and optimum fit parameters were searched with built-in optimisation routines. Deconvolution results are shown for a few challenging spectra with high statistical precision. The algorithm outperforms the best available routines for high-resolution spectrometry, which may facilitate a more reliable determination of alpha emission probabilities in the future. It is also applicable to alpha spectra with inferior energy resolution. PMID:25497323

Pommé, S; Caro Marroyo, B

2015-02-01

215

PIA update: Correlation analyses of mass spectra  

NASA Technical Reports Server (NTRS)

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.

1988-01-01

216

New atlas of IR solar spectra  

NASA Technical Reports Server (NTRS)

Over 4500 absorption lines have been marked on the spectra and the corresponding line positions tabulated. The associated absorbing telluric or solar species for more than 90% of these lines have been identified and only a fraction of the unidentified lines have peak absorptions greater than a few percent. The high resolution and the low Sun spectra greatly enhance the sensitivity limits for identification of trace constituents.

Goldman, A.; Blatherwick, R. D.; Murcray, F. H.; Vanallen, J. W.; Bradford, C. M.; Cook, G. R.; Murcray, D. G.

1980-01-01

217

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

218

Area spectra of near extremal black holes  

E-print Network

Motivated by Maggiore's new interpretation of quasinormal modes, starting from the first law of thermodynamics of black holes, we investigate area spectra of a near extremal Schwarzschild de sitter black hole and a higher dimensional near extremal Reissner-Nordstrom de sitter black hole. We show that the area spectra of all these black holes are equally spaced and irrelevant to the parameters of black holes.

Deyou Chen; Haitang Yang; Xiaotao Zu

2010-04-20

219

Trigonometric Polynomials For Estimation Of Spectra  

NASA Technical Reports Server (NTRS)

Orthogonal sets of trigonometric polynomials used as suboptimal substitutes for discrete prolate-spheroidal "windows" of Thomson method of estimation of spectra. As used here, "windows" denotes weighting functions used in sampling time series to obtain their power spectra within specified frequency bands. Simplified windows designed to require less computation than do discrete prolate-spheroidal windows, albeit at price of some loss of accuracy.

Greenhall, Charles A.

1990-01-01

220

Ion and neutral scattering spectra in LEIS  

Microsoft Academic Search

Low energy ions scattering (LEIS) set-ups equipped with a time-of-flight (TOF) detection system can achieve an experimental resolution <1% for He ions at an energy of about 1keV, corresponding to sub-monolayer depth resolution. Furthermore, spectra of scattered neutrals reveal interesting information on the electronic interaction of the projectiles with the sample.We compare experimental TOF-LEIS spectra to Monte-Carlo simulations (MARLOWE) and

M. Draxler; P. Zeppenfeld; R. Beikler; E. Taglauer; P. Bauer

2005-01-01

221

Power-law tailed spectra from equilibrium  

E-print Network

We propose that power-law tailed hadron spectra may be viewed as stemming from a matter in an unconventional equilibrium state typical for non-extensive thermodynamics. A non-extensive Boltzmann equation, which is able to form such spectra as a stationary solution, is utilized as a rough model of quark matter hadronization. Basic ideas about non-extensive simulation of the QCD equation of state on the lattice are presented.

T. S. Biro; G. Purcsel; G. Gyorgyi; A. Jakovac; Zs. Schram

2005-10-03

222

Impact ionisation spectra of cosmic dust analogues  

NASA Astrophysics Data System (ADS)

The Cassini dust detector CDA collected a few impact spectra of grains which are most likely of interstellar origin. Such spectra provide unequivocal information about the composition of solid material embedded in the interstellar medium, while the current knowledge of the composition of interstellar dust stemming dominantly from astronomical is limited. Fortunately, interstellar grains can be found even in the vicinity of the Earth orbit because the solar system currently traverses the so-called Local Interstellar Cloud (LIC). The interpretation of impact mass spectra is difficult because (i) the impact ionisation is a non-equilibrium process, (ii) new chemical compounds may form in the impact plasma, and (iii) the likelihood to detect elements or molecules in the resulting spectrum depends on the impact energy. To retrieve reliable information about the composition, the CDA spectra need to be related to spectra obtained from impact experiments with dust analogous in a dust accelerator facility. To this aim we performed impact experiments with cosmic dust analogues in a dust accelerator facility. We recorded spectra of sub-micron pyroxene grains ground from a natural Spinel-Lherzolite sample using a high resolution impact mass spectrometer as well as the CDA flight spare unit. In this talk we will report about calibration experiments using the 2MV Van-der-Graaf dust accelerator in Heidelberg.

Kempf, S.; Fiege, K.; Hillier, J.; Srama, R.; Mocker, A.; Postberg, F.; Sternovsky, Z.; Horanyi, M.; Munsat, T.; Drake, K. J.

2011-12-01

223

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

224

Good abundances from bad spectra - I. Techniques  

NASA Astrophysics Data System (ADS)

Stellar spectra derived from multiple-object fibre-fed spectroscopic radial-velocity surveys, of the type feasible with, among other examples, AUTOFIB, 2dF, HYDRA, NESSIE, and the Sloan survey, differ significantly from those traditionally used for determination of stellar abundances. The spectra tend to be of moderate resolution (around 1A) and signal-to-noise ratio (around 10-20 per resolution element), and cannot usually have reliable continuum shapes determined over wavelength ranges in excess of a few tens of Angstroms. None the less, with care and a calibration of stellar effective temperature from photometry, independent of the spectroscopy, reliable iron abundances can be derived. We have developed techniques to extract true iron abundances and surface gravities from low-signal-to-noise ratio, intermediate-resolution spectra of G-type stars in the 4000-5000A wavelength region. Spectroscopic indices sensitive to iron abundance and gravity are defined from a set of narrow (few-several A wide) wavelength intervals. The indices are calibrated theoretically using synthetic spectra. Given adequate data and a photometrically determined effective temperature, one can derive estimates of the stellar iron abundance and surface gravity. We have also defined a single abundance indicator for the analysis of very low-signal-to-noise ratio spectra; with the further assumption of a value for the stellar surface gravity, this is able to provide useful iron abundance information from spectra having signal-to-noise ratios as low as 10 (1-A elements). The theoretical basis and calibration using synthetic spectra are described in this paper. The empirical calibration of these techniques by application to observational data is described in a separate paper (Jones, Wyse & Gilmore). The technique provides precise iron abundances, with zero-point correct to ~0.1 dex, and is reliable, with typical uncertainties being <~0.2 dex. A derivation of the in situ thick disc metallicity distribution using these techniques is presented by Gilmore, Wyse & Jones.

Jones, J. Bryn; Gilmore, Gerard; Wyse, Rosemary F. G.

1996-01-01

225

Fingerprints of correlation in electronic spectra Lucia Reining  

E-print Network

Fingerprints of correlation in electronic spectra Lucia Reining Theoretical Spectroscopy Group #12 Interaction leads to........... additional excitations Fingerprints of correlation in electronic spectra #12

Botti, Silvana

226

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

227

Improving Algorithm for Automatic Spectra Processing  

NASA Astrophysics Data System (ADS)

Testing and improving of the computer program for automatic processing (flat-fielding) of a great number of solar spectra obtained with the horizontal heliospectrograph HSFA2 has been done. This program was developed in the Astronomical Institute of Academy of Sciences of the Czech Republic in Ond?ejov. An irregularity in its work has been discovered, i.e. the program didn't work for some of the spectra. To discover a cause of this error an algorithm has been developed, and a program for examination of the parallelism of reference hairs crossing the spectral slit on records of solar spectra has been made. The standard methods for data processing have been applied-calculating and analyzing higher-order moments of distribution of radiation intensity. The spectra with the disturbed parallelism of the reference hairs have been eliminated from further processing. In order to improve this algorithm of smoothing of spectra, isolation and removal of the harmonic made by a sunspot with multiple elementary transformations of ordinates (Labrouste's transformations) are planned. This project was accomplished at the first summer astronomy practice of students of the Faculty of Mathematics, University of Belgrade, Serbia in 2007 in Ond?ejov.

Rackovic, K.; Nikolic, S.; Kotrc, P.

2009-09-01

228

Spectra from nuclear-excited plasmas  

NASA Technical Reports Server (NTRS)

The paper discusses the spectra taken from He-3(n,p)H-3 nuclear-induced plasmas under high thermal neutron flux, lasing conditions. Also, initial spectra are presented for U-235F6 generated plasmas. From an evaluation of these spectra, important atomic and molecular processes that occur in the plasma can be inferred. The spectra presented are the first to be generated by He-3 and U-235F6 nuclear reactions under high neutron flux, lasing conditions. The U-235(n,ff)FF reaction, which liberates 165 MeV of fission-fragment kinetic energy, creates plasmas that are of great interest, since at sufficiently high densities of U-235F6 the gas becomes self-critical; thus, there is no need for an external driving reactor (source of neutrons). The spectra from mixtures of He-3 and Ar, Xe, Kr, Ne, Cl2, F2 and N2 indicate little difference between high-pressure nuclear-induced plasmas and high-pressure electrically pulsed afterglow plasmas for noble-gas systems

De Young, R. J.; Weaver, W. R.

1980-01-01

229

[Vibrational spectra of Hetian nephrite from Xinjiang].  

PubMed

In previous studies, EMPA, PIXE and others were employed to study the chemical compositions of nephrite separately without a systematical measurement. In the present study, XRF, XRD, IR and LR were used together to examine chemical and spectra characteristics of white, green and black nephrite from Hetian, Xinjiang. XRD results indicate that all nephrite samples consist of tremolite. Then IR spectra of nephrite samples suggest that the M-OH stretching vibration bands show that the M1 and M3 sites are not only occupied by Mg2+ and Fe2+, but also by Fe3+, which is consistent with the chemical compositions of these samples. This information might be useful to understanding the variety of nephrite. Their Raman spectra are almost the same, while some differences exist because of different content of FeO/Fe2O3. PMID:22512177

Zhang, Yong-wang; Liu, Yan; Liu, Tao-tao; Muhetaer, Zari; Liu, Yuan-qing

2012-02-01

230

On the Individuality of Sleep EEG Spectra  

PubMed Central

Research in recent years has supported the hypothesis that many properties of the electroencephalogram (EEG) are specific to an individual. In this study, the intra- and inter-individual variations of sleep EEG signals were investigated. This was carried out by analyzing the stability of the average EEG spectra individually computed for the Rechtschaffen and Kales (RK) sleep stages. Six EEG channels were used to account for the topographical aspect of the analysis. Validity of the results was supported by considering a wide dataset of 174 subjects with normal sleep. Subjects spent two consecutive nights in the sleep laboratory during which EEG recordings were obtained. High similarity between average spectra of two consecutive nights was found considering an individual. More than 89% of the second night recordings were correctly assigned to their counterparts of the first night. The average spectra of sleep EEG computed for each RK sleep stage have shown a high degree of individuality. PMID:23997385

Lewandowski, Achim; Rosipal, Roman; Dorffner, Georg

2013-01-01

231

Collective spectra along the fission barrier  

NASA Astrophysics Data System (ADS)

Discrete and continuous spectra of fissioning nuclei at the humps of fission barriers (Bohr transition states) and in the intermediate wells (superdeformed and hyperdeformed states) play a key role in the calculation of fission cross sections. A theoretical evaluation of the collective parts of the spectra is possible within the framework of the dinuclear system model, which treats the wave function of the fissioning nucleus as a superposition of a mononucleus configuration and two-cluster configurations in a dynamical way, permitting exchange of upper-shell nucleons between clusters. The impact of theoretical spectra on neutron-induced fission cross sections and, in combination with an improved version of the scission-point model, on angular distribution of fission fragments is evaluated for plutonium isotopes of interest to nuclear energy applications.

Shneidman, T. M.; Andreev, A. V.; Pigni, M. T.; Massimi, C.; Vannini, G.; Ventura, A.

2012-12-01

232

Fast Inversion of Solar Ca II Spectra  

NASA Astrophysics Data System (ADS)

We present a fast (Lt1 s per profile) inversion code for solar Ca II lines. The code uses an archive of spectra that are synthesized prior to the inversion under the assumption of local thermodynamic equilibrium (LTE). We show that it can be successfully applied to spectrograph data or more sparsely sampled spectra from two-dimensional spectrometers. From a comparison to a non-LTE inversion of the same set of spectra, we derive a first-order non-LTE correction to the temperature stratifications derived in the LTE approach. The correction factor is close to unity up to log ? ~ –3 and increases to values of 2.5 and 4 at log ? = –6 in the quiet Sun and the umbra, respectively.

Beck, C.; Choudhary, D. P.; Rezaei, R.; Louis, R. E.

2015-01-01

233

BRUCE/KYLIE: Pulsating star spectra synthesizer  

NASA Astrophysics Data System (ADS)

BRUCE and KYLIE, written in Fortran 77, synthesize the spectra of pulsating stars. BRUCE constructs a point-sampled model for the surface of a rotating, gravity-darkened star, and then subjects this model to perturbations arising from one or more non-radial pulsation modes. Departures from adiabaticity can be taken into account, as can the Coriolis force through adoption of the so-called traditional approximation. BRUCE writes out a time-sequence of perturbed surface models. This sequence is read in by KYLIE, which synthesizes disk-integrated spectra for the models by co-adding the specific intensity emanating from each visible point toward the observer. The specific intensity is calculated by interpolation in a large temperature-gravity-wavelength-angle grid of pre-calculated intensity spectra.

Townsend, Rich

2014-12-01

234

Cosmic ray proton spectra at low rigidities  

NASA Technical Reports Server (NTRS)

The cosmic ray proton rigidity spectra have been investigated with data collected in the Low Energy Antiproton (LEAP) balloon flight experiment flown from Prince Albert, Canada in 1987. The LEAP apparatus was designed to measure antiprotons using a superconducting magnet spectrometer with ancillary scintillator, time-of-flight, and liquid Cherenkov detectors. After reaching float altitude the balloon drifted south and west to higher geomagnetic cutoffs. The effect of the changing geomagnetic cutoff on the observed spectra was observed during analysis of the proton data along the balloon trajectory. This is the first measurement of the primary and splash albedo spectra over a wide rigidity range (few hundred MV to about 100 GV) with a single instrument.

Seo, E. S.; Ormes, J. F.; Streitmatter, R. E.; Lloyd-Evans, J.; Jones, W. V.

1990-01-01

235

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

Microsoft Academic Search

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

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

1996-01-01

236

A Catalog of Chandra Grating Spectra  

NASA Astrophysics Data System (ADS)

We are developing a Chandra Grating-Data Archive and Catalog to make all grating spectra more visible and accessible to users. We intend to to provide a simple browser interface to analysis-quality standard spectral products (binned spectra and corresponding response files), with the addition of summary graphical products and model-independent flux properties tables. Such products and a browser interface will make it easy for a user to find observations of a particular object, type of object, or type of observation, to quickly assess the quality and potential usefulness of the spectra, and to download the data and responses as a package if desired. We will include LETG data as well as ACIS CC-mode observations. In addition to the data, portable reprocessing scripts, using CXC and other publicly available software which were used to create the archive will also be available to users, facilitating standard or customized reprocessing from download of Level 1 archive data to production of spectra and responses with minimal interaction (analogous to the "psextract" script commonly used for automated imaging spectral extraction). We will add some customized products which may take time, effort, or special expertise to produce. Candidates for such include extended source extractions, crowded field extractions, and aggregate products such as summed Capella or summed Orion-field-objects spectra. Additional content will grow according to user feedback. This catalog builds upon experience with other relevant work, such as the X-Atlas of HETGS spectra (http://cxc.harvard.edu/XATLAS) or the XMM-RGS spectral browser (http://xmm.esac.esa.int/BiRD). It is intended to be a long-term legacy product for Chandra gratings observations. This work was supported by NASA through the Smithsonian Astrophysical Observatory (SAO) contract SV3-73016 for the Chandra X-Ray Center and Science Instruments.

Huenemoerder, David; Nichols, J.; Mitschang, A.; Dewey, D.; Marshall, H.; Nowak, M.; Schulz, N.; Davis, J. E.; Houck, J. C.; Canizares, C.

2008-03-01

237

The POLLUX database of synthetic stellar spectra  

NASA Astrophysics Data System (ADS)

The POLLUX database of theoretical stellar spectra includes high-resolution synthetic spectra in the optical range, and spectral distribution energies from the UV to the infrared domains. Data are produced using state-of-the-art codes for each spectral type. The aim of the POLLUX database is to offer easy and direct comparison to observational data, as well as to create easily accessed stellar libraries from M dwarfs or red supergiants to hot and massive stars including Wolf-Rayet stars. Here, we review the major steps of the elaboration of such a database : current status, ongoing and further developments. http://pollux.graal.univ-montp2.fr

Palacios, A.; Lèbre, A.; Sanguillon, M.; Maeght, P.

238

On the varying slope of velocity spectra  

NASA Technical Reports Server (NTRS)

Spectra of zonal, meridional and vertical wind velocity, measured during a 24 hour period with the spaced-antenna technique indicate quite a variable slope as a function of height. It is found that the spectral slope (1h to 24h) of all three components correlates with the mean horizontal wind velocity. A possible conclusion is that the frequency dependence of power density of horizontal and vertical fluctuation component apparently depends on the mean wind velocity. However, the vertical spectra at periods larger than about 1 hour can also be influenced by spillover (due to finite radar antenna beam width) from the horizontal fluctuation component or by a Doppler shift.

Rottger, J.

1986-01-01

239

Simultaneous Selective Detection of Multiple Quantum Spectra  

NASA Astrophysics Data System (ADS)

A three-dimensional multiple-quantum NMR experiment that produces individual spectra of all quantum orders is described. The separation of different quantum orders is accomplished via Fourier transformation with respect to the phase of the first two pulses of a generic three-pulse multiple-quantum sequence. This dramatically reduces the time required to obtain several selectively detected spectra and enhances the sensitivity and digital resolution from that obtained using the original two-dimensional technique. The experiment is demonstrated on the protons of para-chlorotoluene dissolved in the nematic liquid crystal Merck ZLI-1132.

Syvitski, R. T.; Burlinson, N.; Burnell, E. E.; Jeener, J.

2002-04-01

240

Augmentation of ENDF/B fission product gamma-ray spectra by calculated spectra  

SciTech Connect

Gamma-ray spectral data of the ENDF/B-V fission product decay data file have been augmented by calculated spectra. The calculations were performed with a model using beta strength functions and cascade gamma-ray transitions. The calculated spectra were applied to individual fission product nuclides. Comparisons with several hundred measured aggregate gamma spectra after fission were performed to confirm the applicability of the calculated spectra. The augmentation was extended to a preliminary ENDF/B-VI file, and to beta spectra. Appendix C provides information on the total decay energies for individual products and some comparisons of measured and aggregate values based on the preliminary ENDF/B-VI files. 15 refs., 411 figs.

Katakura, J. (Japan Atomic Energy Research Inst., Tokai-mura, Naka-gun, Ibaraki-ken (Japan)) [Japan Atomic Energy Research Inst., Tokai-mura, Naka-gun, Ibaraki-ken (Japan); England, T.R. (Los Alamos National Lab., NM (United States)) [Los Alamos National Lab., NM (United States)

1991-11-01

241

The 0.3–30 keV spectra of Powerful Starburst Galaxies: NuSTAR and Chandra observations ofNGC 3256 and NGC 3310  

NASA Astrophysics Data System (ADS)

We present nearly simultaneous Chandra and NuSTAR observations of two actively star-forming galaxies: NGC 3256 and NGC 3310. The NuSTAR galaxy-wide spectra of both galaxies follow steep power law distributions, similar to the spectra of bright individual ultra-luminous X-ray sources (ULXs) that have been studied by NuSTAR. The X-ray emission from both galaxies is spatially resolved by Chandra, which indicates that hot gas dominates the E < 1 – 3 keV emission, while ULXs make up a majority of the emission at E > 1-3 keV. Using new and archival Chandra data we found that both galaxies have candidate AGNs coincident with nuclear regions. However, the steep NuSTAR spectra of both galaxies restricts these candidates to be low luminosity AGN, and a non-AGN nature cannot be ruled out. We find the average 0.3 –30 keV SFR-normalized spectra of NGC 3256 and NGC 3310, combined with equivalent measurements for M83 and NGC 253, show sharpening power-law slopes at energies above 3 – 6 keV due to ULX populations. Our observations therefore constrain the average spectral shape of an unbiased population of ULXs to be similar to the super-Eddington accreting ULXs that have been studied by NuSTAR. We also find that for NGC 3310, there is a factor of 5 times excess X-ray emission, due to an overabundance of ULXs in the galaxy compared to typical galaxies. We argue that the excess is due to the relatively low metallicity of the young stellar population in the galaxy.

NuSTAR Starburst Team

2015-01-01

242

The 0.3–30 keV spectra of Powerful Starburst Galaxies: NuSTAR and Chandra observations ofNGC 3256 and NGC 3310  

NASA Astrophysics Data System (ADS)

We present nearly simultaneous Chandra and NuSTAR observations of two actively star-forming galaxies: NGC 3256 and NGC 3310. The NuSTAR galaxy-wide spectra of both galaxies follow steep power law distributions, similar to the spectra of bright individual ultra-luminous X-ray sources (ULXs) that have been studied by NuSTAR. The X-ray emission from both galaxies is spatially resolved by Chandra, which indicates that hot gas dominates the E < 1 - 3 keV emission, while ULXs make up a majority of the emission at E > 1-3 keV. Using new and archival Chandra data we found that both galaxies have candidate AGNs coincident with nuclear regions. However, the steep NuSTAR spectra of both galaxies restricts these candidates to be low luminosity AGN, and a non-AGN nature cannot be ruled out. We find the average 0.3 -30 keV SFR-normalized spectra of NGC 3256 and NGC 3310, combined with equivalent measurements for M83 and NGC 253, show sharpening power-law slopes at energies above 3 - 6 keV due to ULX populations. Our observations therefore constrain the average spectral shape of an unbiased population of ULXs to be similar to the super-Eddington accreting ULXs that have been studied by NuSTAR. We also find that for NGC 3310, there is a factor of 5 times excess X-ray emission, due to an overabundance of ULXs in the galaxy compared to typical galaxies. We argue that the excess is due to the relatively low metallicity of the young stellar population in the galaxy.

Tyler, Joshua; Lehmer, Bret; Hornschemeier, Ann E.; Yukita, Mihoko; Wik, Daniel R.; Ptak, Andrew; Stern, Daniel; Harrison, Fiona; Maccarone, Tom; Zezas, Andreas; Antoniou, Vallia; NuSTAR Starburst Team

2015-01-01

243

Magic energies in auger electron spectra  

Microsoft Academic Search

The Auger electron spectra in ion-solid interaction exhibit ``magical'' energies. At those energies the electron emission spectrum does not depend on the kinetic energy of the incident ion. We explain this feature in terms of the level broadening of the incoming ion. Furthermore we show that the broadening is proportional to the original ion velocity and we find a new

R. Monreal; S. P. Apell

1993-01-01

244

Ablation spectra of the human cornea  

Microsoft Academic Search

Ablation of human corneal tissue with 193 nm excimer laser energy generates fluorescence in the near ultraviolet and visible regions of the spectrum. The fluorescence spectra from five human corneas were collected during ablation in vitro. We find that the fluorescence spectrum changes continuously at the cornea is ablated from the epithelial surface towards the endothelium. We reduced the dimensionality

David Cohen; Roy S. Chuck; Gregory H. Bearman; Peter J. McDonnell; Warren S. Grundfest

2001-01-01

245

Laboratory millimeter and submillimeter spectra of CO/+/  

NASA Technical Reports Server (NTRS)

The strong electric dipole-allowed transitions of the molecular ion CO(+) in the region 235-470 GHz have been measured in the laboratory. The laboratory spectra at 235 GHz appear to confirm the claim by Erickson et al. (1981) to have observed CO(+) in OMC-1.

Sastry, K. V. L. N.; Helminger, P.; Herbst, E.; De Lucia, F. C.

1981-01-01

246

Power Spectra for Deterministic Chaotic Dynamical Systems  

E-print Network

Power Spectra for Deterministic Chaotic Dynamical Systems Ian Melbourne Georg A. Gottwald 23 July of deterministic chaotic discrete dynamical systems, the power spectrum is analytic except for finitely many for large classes of discrete chaotic dynamical systems, including uniformly hyperbolic (Ax- iom A

Gottwald, Georg A.

247

Power Spectra for Deterministic Chaotic Dynamical Systems  

E-print Network

Power Spectra for Deterministic Chaotic Dynamical Systems Ian Melbourne #3; Georg A. Gottwald y 8 of deterministic chaotic discrete dynamical systems, the power spectrum is analytic except for #12;nitely many for large classes of discrete chaotic dynamical systems, including uniformly hyperbolic (Ax- iom A) di#11

248

Astronomy Spectra Experiment for Nonscience Students.  

ERIC Educational Resources Information Center

An experimental technique to develop inferential thinking in less scientifically-oriented community college students is described. Students activate unlabeled gas discharge tubes and identify the gases by comparing color photographs with spectrometer observations. Includes methods for taking color photographs of spectra. (SK)

Kaufman, S. E.

1982-01-01

249

Chaotic spectra: How to extract dynamic information  

SciTech Connect

Nonlinear dynamics is applied to chaotic unassignable atomic and molecular spectra with the aim of extracting detailed information about regular dynamic motions that exist over short intervals of time. It is shown how this motion can be extracted from high resolution spectra by doing low resolution studies or by Fourier transforming limited regions of the spectrum. These motions mimic those of periodic orbits (PO) and are inserts into the dominant chaotic motion. Considering these inserts and the PO as a dynamically decoupled region of space, resonant scattering theory and stabilization methods enable us to compute ladders of resonant states which interact with the chaotic quasi-continuum computed in principle from basis sets placed off the PO. The interaction of the resonances with the quasicontinuum explains the low resolution spectra seen in such experiments. It also allows one to associate low resolution features with a particular PO. The motion on the PO thereby supplies the molecular movements whose quantization causes the low resolution spectra. Characteristic properties of the periodic orbit based resonances are discussed. The method is illustrated on the photoabsorption spectrum of the hydrogen atom in a strong magnetic field and on the photodissociation spectrum of H/sub 3//sup +/. Other molecular systems which are currently under investigation using this formalism are also mentioned. 53 refs., 10 figs., 2 tabs.

Taylor, H.S.; Gomez Llorente, J.M.; Zakrzewski, J.; Kulander, K.C.

1988-10-01

250

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

251

Optical Emission Spectra of Plasma Display Panel  

SciTech Connect

In this study, optical emission spectra of plasma display panel (PDP) was investigated between 200-850 nm at various pressure, pure (Ar) an mixture gas (0,5Ar+0,5 N2). This device is an application of dielectric barrier discharge.

Pat, S.; Ekem, N.; Balbag, M. Z.; Cenik, M. I.; Akan, T.; Aydin, O. [Eskisehir Osmangazi University, Physics Department, Eskisehir (Turkey); Musa, G.; Surdu-Bob, C. C. [National Institude of Plasma Physics, Bucharest (Romania)

2007-04-23

252

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

253

Atomic Models and X-Ray Spectra  

Microsoft Academic Search

IN the recent discussion in NATURE on the constitution of the atom, attention has been directed mainly to the electrostatic forces exerted by the positively charged portion of the atom. Prof. Nicholson has been successful in calculating the frequencies of the lines in the nebular and coronal spectra on this basis by employing Rutherford's model atom consisting-of a central nucleus

H. S. Allen

1914-01-01

254

Atomic Models and X-Ray Spectra  

Microsoft Academic Search

DR. F. A. LINDEMANN (NATURE, January 1) disagrees with the theoretical interpretation of my recent work on X-ray spectra (Phil. Mag., December, 1913). He objects to my statement that the results so far obtained strongly support the views of Bohr, and considers that they yield no information about the structure of the atom beyond confirming the views of Rutherford and

H. Moseley

1914-01-01

255

FT-IR spectra of inorganic borohydrides.  

PubMed

Inorganic compounds with BH4(-) ions are the subject of many recent investigations in the context of potential hydrogen storage materials. In this work, Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectra of a series of reference and research compounds (including deuterated samples) are collected and made available to the research community. PMID:24717677

D'Anna, Vincenza; Spyratou, Alexandra; Sharma, Manish; Hagemann, Hans

2014-07-15

256

Absorption spectra of alkali-C?? nanoclusters.  

PubMed

We investigate the absorption spectra of alkali-doped C60 nanoclusters, namely C60Nan, C60Kn, and C60Lin, with n = 1, 2, 6, 12, in the framework of the time-dependent density-functional theory (TDDFT). We study the dependence of the absorption spectra on the nature of the alkali. We show that in few cases the absorption spectra depend on the arrangement of the alkali atoms over the fullerene, though sometimes the absorption spectra do not allow us to distinguish between different configurations. When only one or two alkali atoms are adsorbed on the fullerene, the optical response of alkali-doped C60 is similar to that of the anion C60(-) with a strong response in the UV domain. In contrast, for higher concentration of alkali, a strong optical response is predicted in the visible range, particularly when metal-metal bonds are formed. The weak optical response of the I(h)-symmetry C60Li12 is proposed to be used as a signature of its structure. PMID:25223347

Rabilloud, Franck

2014-10-28

257

EEG Power Spectra of Adolescent Poor Readers.  

ERIC Educational Resources Information Center

Electroencephalographic power spectra were studied in two poor-reading adolescent groups (n=38), dysphonetic and phonetic. Significant Group x Hemisphere effects were found in the alpha and beta bands, with the phonetic group showing right greater than left asymmetry. Results suggest more circumscribed and mature processing in the phonetically…

Ackerman, Peggy T.; McPherson, W. Brian; Oglesby, D. Michael; Dykman, Roscoe A.

1998-01-01

258

CALCULATION OF ION ENERGY-DEPOSITION SPECTRA  

E-print Network

CALCULATION OF ION ENERGY-DEPOSITION SPECTRA IN SILICON, LITHIUM-FLUORIDE, BORON, AND BORON CARBIDE applications it is important to be able to calculate the energy deposited in the medium through which the ions pass. In this report empirical formulas are presented that allow rapid calculation of (1) the stopping

Shultis, J. Kenneth

259

Vacuum ultraviolet spectra of carbonaceous chondrites  

Microsoft Academic Search

In the present paper, the vacuum ultraviolet reflection spectra of carbonaceous chondrite polished thin-section and powder are compared in terms of the energy-gap (Eg) value within the region from 5 to 14 eV. The comparison is carried out for the Essebi, Isna, Vigarano, Karoonda, Orgueil, and Allende chondrites and for meteoritic fassites, fayelites, and forsteritic peridot crystals.

A. J. Cohen; J. K. Wagner; B. W. Hapke; W. D. Partlow

1978-01-01

260

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

261

[Characteristics analysis of human tongue reflectance spectra].  

PubMed

The present paper presents the spectroscopic analysis method. Eighty samples of spectra data of tongue parts with coating and without coating were collected by Usb4000 spectrometer of Ocean Optics, then comparing the spectra data of the different parts of tongue we found that there was a relation between the spectra characteristics and tongue coating, and further analysis of the spectra data showed that there was a big difference between the two parts within the wavelength range between 500 and 600 nm. It was also found that the biggest differences appear when the wavelength is 579.39 nm, and at the same time, different colors of tongue coating were also compared, and the spectrum was also quite different because of different color and thickness of the tongue coating. The experiment results show that different color, thickness, and dryness of the human tongue coating lead to different spectral characteristics, and compared with the current colorimetric method of tongue characterization, spectral reflectance can reflect more physiological and pathological information. The experiment results also indicated that the different spectral characteristics of tongue property and tongue coating will be used for further separation of these two parts, and to provide an objective analysis index for tongue coating qualitative and quantitative analysis, so as to promote the objectivity of the TCM. PMID:25508742

Zhao, Jing; Liu, Ming; Lu, Xiao-zuo; Li, Gang

2014-08-01

262

[Characteristics analysis of human tongue reflectance spectra].  

PubMed

The present paper presents the spectroscopic analysis method. Eighty samples of spectra data of tongue parts with coating and without coating were collected by Usb4000 spectrometer of Ocean Optics, then comparing the spectra data of the different parts of tongue we found that there was a relation between the spectra characteristics and tongue coating, and further analysis of the spectra data showed that there was a big difference between the two parts within the wavelength range between 500 and 600 nm. It was also found that the biggest differences appear when the wavelength is 579.39 nm, and at the same time, different colors of tongue coating were also compared, and the spectrum was also quite different because of different color and thickness of the tongue coating. The experiment results show that different color, thickness, and dryness of the human tongue coating lead to different spectral characteristics, and compared with the current colorimetric method of tongue characterization, spectral reflectance can reflect more physiological and pathological information. The experiment results also indicated that the different spectral characteristics of tongue property and tongue coating will be used for further separation of these two parts, and to provide an objective analysis index for tongue coating qualitative and quantitative analysis, so as to promote the objectivity of the TCM. PMID:25474963

Zhao, Jing; Liu, Ming; Lu, Xiao-zuo; Li, Gang

2014-08-01

263

The Transverse Proximity Effect in Quasar Spectra  

E-print Network

The Transverse Proximity Effect in Quasar Spectra G´abor Worseck Astrophysikalisches Institut field generated by the overall population of quasars and star-forming galaxies. In the vicinity of sources of UV photons, such as luminous high-redshift quasars, the UV radiation field is enhanced due

264

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

265

Improved Predictions of Reactor Antineutrino Spectra  

E-print Network

We report new calculations of reactor antineutrino spectra 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 to 20% range. A prediction of the antineutrino spectrum associated with the fission of 238U is given based on this ab initio method. For the dominant isotopes 235U and 239Pu, we developed a more accurate approach combining information from nuclear databases and reference electron spectra associated with the fission of 235U, 239Pu and 241Pu, measured at ILL in the 80's. 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 235U, 239Pu and 241Pu isotopes in the 2-8 MeV range. While the shapes of the spectra and their uncertainties are comparable to that of the previous analysis of the ILL data, the normalization is shifted by about +3% on average. In the perspective of the re-analysis 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.

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

2011-03-11

266

Reflectance spectra of mafic silicate-opaque assemblages with applications to meteorite spectra  

NASA Astrophysics Data System (ADS)

The addition of fine-grained magnetite to mafic silicate spectra can impart not only an overall blue slope, but also lower overall reflectance and band intensities. The reflectance spectra of the CO and CV magnetite-bearing carbonaceous chondrites are noted to exhibit many of these features; the low band depths of these meteorites suggest that an additional dark, neutral phase, such as ordered carbon, is present. Carbon + mafic silicate spectra possess a red overall slope at low amorphous carbon concentrations. The parent bodies of some of the darkest meteorites should exhibit spectral features attributable to mafic silicates.

Cloutis, E. A.; Gaffey, M. J.; Smith, D. G. W.; Lambert, R. St. J.

1990-04-01

267

Nuclear structure insights into reactor antineutrino spectra  

NASA Astrophysics Data System (ADS)

Antineutrino spectra following the neutron induced fission of 235U ,238U ,239Pu, and 241Pu are calculated using the summation approach. While each system involves the decay of more than 800 fission products, the energy region of the spectra most relevant to neutrino oscillations and the reactor antineutrino anomaly is dominated by fewer than 20 nuclei, for which we provide a priority list to drive new measurements. The very-high-energy portion of the spectrum is mainly due to the decay of just two nuclides, 92Rb and 96Y. The integral of the signal measured by antineutrino experiments is found to have a dependence on the mass and proton numbers of the fissioning system. In addition, we observe that ˜70 % of the signal originates from the light fission fragment group and about 50 % from the decay of odd-Z , odd-N nuclides.

Sonzogni, A. A.; Johnson, T. D.; McCutchan, E. A.

2015-01-01

268

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

269

An approach to heavy quarkonium spectra  

NASA Astrophysics Data System (ADS)

An application of the recently introduced method [M. Çapak et al., J. Math. Phys. 52, 102102 (2011)] to the bound-state eigenvalue problem in the elementary quarkonium potential V(r) = -a/r + br + cr2 is described, proved and illustrated for c\\bar {c} and b\\bar {b} systems. The quasi- and conditionally-exactly solvable spin-averaged mass spectra of heavy quarkonia are obtained in compact forms. The comparison of the present predictions with those of other theories in the related literature, together with the available data, has shown the success of the model used in this work and also revealed that the use of different confinings in the perturbed Coulomb potential descriptions has no considerable effect on the mass spectra of such systems.

Cançelik, Y.; Gönül, B.

2014-10-01

270

Characteristics of magnetospheric radio noise spectra  

NASA Technical Reports Server (NTRS)

Magnetospheric radio noise spectra (30 kHz to 10 MHz) taken by IMP-6 and RAE-2 exhibit time-varying characteristics which are related to spacecraft position and magnetospheric processes. In the mid-frequency range (100-1,000 kHz) intense noise peaks rise by a factor of 100 or more above background; 80% of the peak frequencies are within the band 125 kHz to 600 kHz, and the peak occurs most often (18% of the time) at 280 kHz. This intense mid-frequency noise has been detected at radial distances from 1.3 Re to 60 Re on all sides of the Earth during magnetically quiet as well as disturbed periods. Maximum occurrence of the mid-frequency noise is in the evening to midnight hours where splash-type energetic particle precipitation takes place. ""Magnetospheric lightning'' can be invoked to explain the spectral shape of the observed spectra.

Herman, J. R.

1976-01-01

271

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

272

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

273

Benchmarking statistical averaging of spectra with HULLAC  

NASA Astrophysics Data System (ADS)

Knowledge of radiative properties of hot plasmas is important for ICF, astrophysics, etc When mid-Z or high-Z elements are present, the spectra are so complex that one commonly uses statistically averaged description of atomic systems [1]. In a recent experiment on Fe[2], performed under controlled conditions, high resolution transmission spectra were obtained. The new version of HULLAC [3] allows the use of the same model with different levels of details/averaging. We will take advantage of this feature to check the effect of averaging with comparison with experiment. [1] A Bar-Shalom, J Oreg, and M Klapisch, J. Quant. Spectros. Rad. Transf. 65, 43 (2000). [2] J. E. Bailey, G. A. Rochau, C. A. Iglesias et al., Phys. Rev. Lett. 99, 265002-4 (2007). [3]. M. Klapisch, M. Busquet, and A. Bar-Shalom, AIP Conference Proceedings 926, 206-15 (2007).

Klapisch, Marcel; Busquet, Michel

2008-11-01

274

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

275

Electric field representation of pulsar intensity spectra  

E-print Network

Pulsar dynamic spectra exhibit high visibility fringes arising from interference between scattered radio waves. These fringes may be random or highly ordered patterns, depending on the nature of the scattering or refraction. Here we consider the possibility of decomposing pulsar dynamic spectra -- which are intensity measurements -- into their constituent scattered waves, i.e. electric field components. We describe an iterative method of achieving this decomposition and show how the algorithm performs on data from the pulsar B0834+06. The match between model and observations is good, although not formally acceptable as a representation of the data. Scattered wave components derived in this way are immediately useful for qualitative insights into the scattering geometry. With some further development this approach can be put to a variety of uses, including: imaging the scattering and refracting structures in the interstellar medium; interstellar interferometric imaging of pulsars at very high angular resolution; and mitigating pulse arrival time fluctuations due to interstellar scattering.

Mark Walker; Dan Stinebring

2005-08-08

276

Core-level spectra from graphene  

NASA Astrophysics Data System (ADS)

We calculate core-level spectra for pristine and doped free-standing graphene sheets. Instructions for how to perform the calculations are given in detail. Although pristine graphene is not metallic the core-level spectrum presents low-energy tailing which is characteristic of metallic systems. The peak shapes vary with doping level in a characteristic way. The spectra are compared to experiments and show good agreement. We compare to two different pristine samples and to one doped sample. The pristine samples are one with quasi-free-standing epitaxial graphene on SiC obtained by hydrogen intercalation and one with a suspended graphene sheet. The doped sample is a gold supported graphene sheet. The gold substrate acts as an acceptor so the graphene sheet gets p doped.

Sernelius, Bo E.

2015-01-01

277

Magic energies in auger electron spectra  

NASA Astrophysics Data System (ADS)

The Auger electron spectra in ion-solid interaction exhibit "magical" energies. At those energies the electron emission spectrum does not depend on the kinetic energy of the incident ion. We explain this feature in terms of the level broadening of the incoming ion. Furthermore we show that the broadening is proportional to the original ion velocity and we find a new method for extracting the "true" unbroadened spectrum.

Monreal, R.; Apell, S. P.

1993-12-01

278

Understanding the baryon and meson spectra  

SciTech Connect

A brief overview is given of what we know of the baryon and meson spectra, with a focus on what are the key internal degrees of freedom and how these relate to strong coupling QCD. The challenges, experimental, theoretical and phenomenological, for the future are outlined, with particular reference to a program at Jefferson Lab to extract hadronic states in which glue unambiguously contributes to their quantum numbers.

Pennington, Michael R. [JLAB

2013-10-01

279

Reanalysis of Tyrannosaurus rex Mass Spectra.  

PubMed

Asara et al. reported the detection of collagen peptides in a 68-million-year-old Tyrannosaurus rex bone by shotgun proteomics. This finding has been called into question as a possible statistical artifact. We reanalyze Asara et al.'s tandem mass spectra using a different search engine and different statistical tools. Our reanalysis shows a sample containing common laboratory contaminants, soil bacteria, and bird-like hemoglobin and collagen. PMID:19603827

Bern, Marshall; Phinney, Brett S; Goldberg, David

2009-09-01

280

Dose spectra from energetic particles and neutrons  

NASA Astrophysics Data System (ADS)

spectra from energetic particles and neutrons (DoSEN) are an early-stage space technology research project that combines two advanced complementary radiation detection concepts with fundamental advantages over traditional dosimetry. DoSEN measures not only the energy but also the charge distribution (including neutrons) of energetic particles that affect human (and robotic) health in a way not presently possible with current dosimeters. For heavy ions and protons, DoSEN provides a direct measurement of the lineal energy transfer (LET) spectra behind shielding material. For LET measurements, DoSEN contains stacks of thin-thick Si detectors similar in design to those used for the Cosmic Ray Telescope for the Effects of Radiation. With LET spectra, we can now directly break down the observed spectrum of radiation into its constituent heavy-ion components and through biologically based quality factors that provide not only doses and dose rates but also dose equivalents, associated rates, and even organ doses. DoSEN also measures neutrons from 10 to 100 MeV, which requires enough sensitive mass to fully absorb recoil particles that the neutrons produce. DoSEN develops the new concept of combining these independent measurements and using the coincidence of LET measurements and neutron detection to significantly reduce backgrounds in each measurement. The background suppression through the use of coincidence allows for significant reductions in size, mass, and power needed to provide measurements of dose, neutron dose, dose equivalents, LET spectra, and organ doses. Thus, we introduce the DoSEN concept: a promising low-mass instrument that detects the full spectrum of energetic particles, heavy ions, and neutrons to determine biological impact of radiation in space.

Schwadron, Nathan; Bancroft, Chris; Bloser, Peter; Legere, Jason; Ryan, James; Smith, Sonya; Spence, Harlan; Mazur, Joe; Zeitlin, Cary

2013-10-01

281

Ultraviolet spectra of R Coronae Borealis stars  

NASA Technical Reports Server (NTRS)

An analysis of the International Ultraviolet Explorer spectra of the R CrB-type variables R CrB, RY Sgr, XX Cam, and MV Sgr suggests that: (1) it should be possible to construct useful models for the atmospheres of these hydrogen deficient, carbon rich stars if present standards of metallic line blanketing are used; and (2) the observed wavelength dependence of the circumstellar extinction is primarily due to circumstellar grains.

Holm, A. V.; Wu, C. C.

1982-01-01

282

Electronic spectra of astrophysically interesting cations  

NASA Astrophysics Data System (ADS)

The electronic spectra of polyacetylene cations were recorded at 20K in the laboratory in an ion trap instrument. These can then be compared with diffuse interstellar band (DIB) absorptions. Examination of recently published data shows that the attribution of a weak DIB at ˜506.9 nm to diacetylene cation is not justified. Study of the higher excited electronic states of polyacetylene cations shows that their widths can still be sufficiently narrow for consideration as DIB carriers.

Maier, John P.; Rice, Corey A.; Mazzotti, Fabio J.; Johnson, Anatoly

2015-01-01

283

Auger electron spectra of Mg thin films  

Microsoft Academic Search

The effect of oxidation on Mg thin films is studied by Auger electron spectroscopy. Several films are prepared from Mg of purity 99.999% under a pressure of 10-6-10-8 Torr in the thickness range 200-25 000 ÅA. The spectra from these films are measured on an ESCA-36 spectrometer with Al Kalpha excitation line under a pressure of about 10-8 Torr. The

N. C. Halder; J. Alonso Jr.; W. E. Swartz Jr.

1976-01-01

284

Reanalysis of Tyrannosaurus rex Mass Spectra  

PubMed Central

Asara et al. reported the detection of collagen peptides in a 68-million-year-old T. rex bone by shotgun proteomics. This finding has been called into question as a possible statistical artifact. We reanalyze Asara et al.'s tandem mass spectra using a different search engine and different statistical tools. Our reanalysis shows a sample containing common laboratory contaminants, soil bacteria, and bird-like hemoglobin and collagen. PMID:19603827

Bern, Marshall; Phinney, Brett S.; Goldberg, David

2009-01-01

285

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

286

Computing High Accuracy Power Spectra with Pico  

E-print Network

This paper presents the second release of Pico (Parameters for the Impatient COsmologist). Pico is a general purpose machine learning code which we have applied to computing the CMB power spectra and the WMAP likelihood. For this release, we have made improvements to the algorithm as well as the data sets used to train Pico, leading to a significant improvement in accuracy. For the 9 parameter nonflat case presented here Pico can on average compute the TT, TE and EE spectra to better than 1% of cosmic standard deviation for nearly all $\\ell$ values over a large region of parameter space. Performing a cosmological parameter analysis of current CMB and large scale structure data, we show that these power spectra give very accurate 1 and 2 dimensional parameter posteriors. We have extended Pico to allow computation of the tensor power spectrum and the matter transfer function. Pico runs about 1500 times faster than CAMB at the default accuracy and about 250,000 times faster at high accuracy. Training Pico can be done using massively parallel computing resources, including distributed computing projects such as Cosmology@Home. On the homepage for Pico, located at http://cosmos.astro.uiuc.edu/pico, we provide new sets of regression coefficients and make the training code available for public use.

William A. Fendt; Benjamin D. Wandelt

2007-12-02

287

Infrared spectra of substituted polycylic aromatic hydrocarbons  

NASA Technical Reports Server (NTRS)

Calculations are carried out using density functional theory (DFT) to determine the harmonic frequencies and intensities of 1-methylanthracene, 9-methylanthracene, 9-cyanoanthracene, 2-aminoanthracene, acridine, and their positive ions. The theoretical data are compared with matrix-isolation spectra for these species also reported in this work. The theoretical and experimental frequencies and relative intensities for the neutral species are in generally good agreement, whereas the positive ion spectra are only in qualitative agreement. Relative to anthracene, we find that substitution of a methyl or CN for a hydrogen does not significantly affect the spectrum other than to add the characteristic methyl C-H and C triple bond N stretches near 2900 and 2200 cm-1, respectively. However, addition of NH2 dramatically affects the spectrum of the neutral. Not only are the NH2 modes themselves strong, but this electron-withdrawing group induces sufficient partial charge on the ring to give the neutral molecule spectra characteristics of the anthracene cation. The sum of the absolute intensities is about four times larger for 2-aminoanthracene than those for 9-cyanoanthracene. Substituting nitrogen in the ring at the nine position (acridine) does not greatly alter the spectrum compared with anthracene.

Langhoff, S. R.; Bauschlicher, C. W. Jr; Hudgins, D. M.; Sandford, S. A.; Allamandola, L. J.

1998-01-01

288

IRAS Low Resolution Spectra of Asteroids  

NASA Technical Reports Server (NTRS)

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.

2002-01-01

289

The Transit Spectra of Earth and Jupiter  

E-print Network

In recent years, a number of observations have been made of the transits of 'Hot Jupiters', such as HD 189733b, which have been modelled to derive atmospheric structure and composition. As measurement techniques improve, the transit spectra of 'Super-Earths' such as GJ 1214b are becoming better constrained, allowing model atmospheres to be fitted for this class of planet also. While it is not yet possible to constrain the atmospheric states of small planets such as the Earth or cold planets like Jupiter, this may become practical in the coming decades and if so, it is of interest to determine what we might infer from such measurements. Here we have constructed atmospheric models of the Solar System planets from 0.4 - 15.5 microns that are consistent with ground-based and satellite observations and from these calculate the primary transit and secondary eclipse spectra (with respect to the Sun and typical M-dwarfs) that would be observed by a 'remote observer', many light years away. From these spectra we test ...

Irwin, Patrick G J; Bowles, Neil E; Fletcher, Leigh N; Aigrain, Suzanne; Lee, Jae-Min

2014-01-01

290

Soil emissivity and reflectance spectra measurements.  

PubMed

We present an analysis of the laboratory reflectance and emissivity spectra of 11 soil samples collected on different field campaigns carried out over a diverse suite of test sites in Europe, North Africa, and South America from 2002 to 2008. Hemispherical reflectance spectra were measured from 2.0 to 14 microm with a Fourier transform infrared spectrometer, and x-ray diffraction analysis (XRD) was used to determine the mineralogical phases of the soil samples. Emissivity spectra were obtained from the hemispherical reflectance measurements using Kirchhoff's law and compared with in situ radiance measurements obtained with a CIMEL Electronique CE312-2 thermal radiometer and converted to emissivity using the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) temperature and emissivity separation algorithm. The CIMEL has five narrow bands at approximately the same positions as the ASTER. Results show a root mean square error typically below 0.015 between laboratory emissivity measurements and emissivity measurements derived from the field radiometer. PMID:19571921

Sobrino, José A; Mattar, Cristian; Pardo, Pablo; Jiménez-Muñoz, Juan C; Hook, Simon J; Baldridge, Alice; Ibañez, Rafael

2009-07-01

291

MAGNETIC ENERGY SPECTRA IN SOLAR ACTIVE REGIONS  

SciTech Connect

Line-of-sight magnetograms for 217 active regions (ARs) with different flare rates observed at the solar disk center from 1997 January until 2006 December are utilized to study the turbulence regime and its relationship to flare productivity. Data from the SOHO/MDI instrument recorded in the high-resolution mode and data from the BBSO magnetograph were used. The turbulence regime was probed via magnetic energy spectra and magnetic dissipation spectra. We found steeper energy spectra for ARs with higher flare productivity. We also report that both the power index, {alpha}, of the energy spectrum, E(k) {approx} k{sup -}{alpha}, and the total spectral energy, W = {integral}E(k)dk, are comparably correlated with the flare index, A, of an AR. The correlations are found to be stronger than those found between the flare index and the total unsigned flux. The flare index for an AR can be estimated based on measurements of {alpha} and W as A = 10{sup b}({alpha}W){sup c}, with b = -7.92 {+-} 0.58 and c = 1.85 {+-} 0.13. We found that the regime of the fully developed turbulence occurs in decaying ARs and in emerging ARs (at the very early stage of emergence). Well-developed ARs display underdeveloped turbulence with strong magnetic dissipation at all scales.

Abramenko, Valentyna; Yurchyshyn, Vasyl [Big Bear Solar Observatory, 40386 N. Shore Lane, Big Bear City, CA 92314 (United States)

2010-09-01

292

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

293

The Minnesota Corn Evaluation Program was conducted by the University of Minnesota Agricultural Experiment Station to provide unbiased information for use by corn growers when they choose which brand of corn to buy and grow. The program was financed in pa  

E-print Network

The Minnesota Corn Evaluation Program was conducted by the University of Minnesota Agricultural Experiment Station to provide unbiased information for use by corn growers when they choose which brand of corn to buy and grow. The program was financed in part by entry fees from private seed companies

Weiblen, George D

294

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

295

Infrared absorption spectra, radiative efficiencies, and global warming potentials  

E-print Network

Infrared absorption spectra, radiative efficiencies, and global warming potentials absorption spectra, radiative efficiencies, and global warming potentials of perfluorocarbons: Comparison. (1995) and combined with atmospheric lifetimes from the literature to determine global warming

Wirosoetisno, Djoko

296

SAR-ocean wave inversion using image cross spectra  

Microsoft Academic Search

Image cross-spectra obtained by combining pairs of single look SAR images are utilized in an inversion scheme for extracting the underlying ocean wave spectrum. The reasons for proposing the use of image cross-spectra instead of standard multilook spectra are twofold. First, the image cross-spectra are shown to significantly reduce the speckle noise level while preserving the spectral shape. Second, the

Geir Engen; Harald Johnsen

1995-01-01

297

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

298

Recombination spectra of Helium-Like Ions  

E-print Network

We calculate the recombination spectra of the He-like ions He~I, C~V, N~VI, O~VII, Ne~IX, Mg~XI, Si~XIII, S~XV, Ar~XVII, Ca~XIX, and Fe~XXV. We include the following physical processes: radiative recombination, dielectronic recombination, three-body recombination, electron impact ionization, and collisional excitation by electrons, protons, and $\\alpha$-particles. The calculations account for the effects of lowering of the continuum at high densities and high density corrections to dielectronic recombination. Then we construct models for He-like ions for fast computation of their spectra. Every model includes 29 bound levels up to n=5 and 6 doubly excited levels that account for the most important satellite lines. The models are constructed in a way that allows for proper approach to LTE under appropriate conditions. These models can simultaneously solve for the H/He-like ionization balance in photoionized or collisionally ionized plasmas and compute emission spectra including the combined effects of radiative and dielectronic recombination, collisional excitation, photoionization from excited levels, fluorescence, and line trapping. The models can be used for any temperature between 100 and $10^9$K and electron densities of up to $10^{18}$ \\cm3. The models can be easily used within spectral modeling codes or as stand-alone tools for spectral analysis. We present comparisons between the results of the present models and previous work. Significant differences are found between the present effective recombination rate coefficients to the $n=2$ and those of previous estimates. Later, we study various emission line ratio diagnostics under collisional ionization and photoionized conditions.

M. A. Bautista; T. R. Kallman

2000-06-26

299

Effect of Temperature on Jet Velocity Spectra  

NASA Technical Reports Server (NTRS)

Statistical jet noise prediction codes that accurately predict spectral directivity for both cold and hot jets are highly sought both in industry and academia. Their formulation, whether based upon manipulations of the Navier-Stokes equations or upon heuristic arguments, require substantial experimental observation of jet turbulence statistics. Unfortunately, the statistics of most interest involve the space-time correlation of flow quantities, especially velocity. Until the last 10 years, all turbulence statistics were made with single-point probes, such as hotwires or laser Doppler anemometry. Particle image velocimetry (PIV) brought many new insights with its ability to measure velocity fields over large regions of jets simultaneously; however, it could not measure velocity at rates higher than a few fields per second, making it unsuitable for obtaining temporal spectra and correlations. The development of time-resolved PIV, herein called TR-PIV, has removed this limitation, enabling measurement of velocity fields at high resolution in both space and time. In this paper, ground-breaking results from the application of TR-PIV to single-flow hot jets are used to explore the impact of heat on turbulent statistics of interest to jet noise models. First, a brief summary of validation studies is reported, undertaken to show that the new technique produces the same trusted results as hotwire at cold, low-speed jets. Second, velocity spectra from cold and hot jets are compared to see the effect of heat on the spectra. It is seen that heated jets possess 10 percent more turbulence intensity compared to the unheated jets with the same velocity. The spectral shapes, when normalized using Strouhal scaling, are insensitive to temperature if the stream-wise location is normalized relative to the potential core length. Similarly, second order velocity correlations, of interest in modeling of jet noise sources, are also insensitive to temperature as well.

Bridges, James E.; Wernet, Mark P.

2007-01-01

300

Nuclear reactor fissile isotopes antineutrino spectra  

E-print Network

Positron spectrum from inverse beta decay reaction on proton was measured in 1988-1990 as a result of neutrino exploration experiment. The measured spectrum has the largest statistics and lowest energy threshold between other neutrino experiments made that time at nuclear reactors. On base of the positron spectrum the standard antineutrino spectrum for typical reactor fuel composition was restored. In presented analysis the partial spectra forming this standard spectrum were extracted using specific method. They could be used for neutrino experiments data analysis made at any fuel composition of reactor core.

V. Sinev

2012-07-30

301

Ultraviolet Spectra of Normal Spiral Galaxies  

NASA Technical Reports Server (NTRS)

The data related to this grant on the Ultraviolet Spectra of Normal Spiral Galaxies have been entirely reduced and analyzed. It is incorporated into templates of Spiral galaxies used in the calculation of K corrections towards the understanding of high redshift galaxies. The main paper was published in the Astrophysical Journal, August 1996, Volume 467, page 38. The data was also used in another publication, The Spectral Energy Distribution of Normal Starburst and Active Galaxies, June 1997, preprint series No. 1158. Copies of both have been attached.

Kinney, Anne

1997-01-01

302

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

303

Glow Sticks: Spectra and Color Mixing  

NASA Astrophysics Data System (ADS)

Glow sticks are a popular Halloween staple familiar to most of our students. The production of light via a chemical reaction is called "chemiluminescence," and glow sticks are often used as demonstrations and experiments in the chemistry classroom to study reaction rates as a function of temperature.1-3 A black light can be used to illuminate glow sticks that have not been cracked or those that are "dead" in order to demonstrate fluorescence in liquid chemicals.4 In this article, we present the use of glow sticks as an inexpensive demonstration of spectra and color addition.

Birriel, Jennifer; Birriel, Ignacio

2014-10-01

304

Fine structure in cosmic ray spectra  

NASA Astrophysics Data System (ADS)

The case is made for there being more 'structure' in the cosmic ray energy spectra than just the well-known knee at several PeV and the ankle at several EeV. Specifically, there seems to be a 'dip' or 'kink' at about 100 GeV/nucleon, a possible 'bump' at about 10 TeV, an 'iron peak' at 60 PeV and the possibility of further structure before the ankle is reached. The significance of the structures will be assessed.

Wolfendale, A. W.; Erlykin, A. D.

2013-02-01

305

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

306

Uncertainty Quantification on Prompt Fission Neutrons Spectra  

SciTech Connect

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 {sup 235}U from thermal up to 15 MeV incident energies.

Talou, P. [T-16, Nuclear Physics Group, Los Alamos National Laboratory, NM 87545 (United States)], E-mail: talou@lanl.gov; Madland, D.G.; Kawano, T. [T-16, Nuclear Physics Group, Los Alamos National Laboratory, NM 87545 (United States)

2008-12-15

307

Solar Doppler shifts - Sources of continuous spectra  

NASA Technical Reports Server (NTRS)

Oscillation observations can be used to study nonoscillatory solar phenomena that exhibit Doppler shifts. The paper discusses several effects of these phenomena and their associated temporal and spatial power spectra: (1) they limit the signal-to-noise ratio and sometimes detectability of oscillation modes; (2) there is the potential for better understanding and/or detection of solar phenomena; (3) large-scale convection may spatially modulate oscillation modes, leading to a continuous background spectrum; and (4) in regions of the spectrum where the resolution to separate modes is lacking one can determine upper limits for the integrated effects of modes.

Duvall, T. L., Jr.; Harvey, J. W.

1986-01-01

308

Abundance analysis of HD 22920 spectra  

NASA Astrophysics Data System (ADS)

The new spectropolarimetric observations of HD 22920 with ESPaDOnS at CFHT reveal a strong variability of its spectral line profiles with the phase of stellar rotation. We have obtained T eff = 13640 K, logg=3.72 for this star from the best fit of its nine Balmer line profiles. The respective model of stellar atmosphere was calculated to perform abundance analysis of HD 22920 using the spectra obtained for three different phases of stellar rotation. We have found that silicon and chromium abundances appear to be vertically stratified in the atmosphere of HD 22920. Meanwhile, silicon shows hints for a possible variability of vertical abundance stratification with rotational phase.

Khalack, Viktor; Poitras, Patrick

2015-01-01

309

Multifractal spectra in homogeneous shear flow  

NASA Technical Reports Server (NTRS)

Employing numerical simulations of 3-D homogeneous shear flow, the associated multifractal spectra of the energy dissipation, scalar dissipation and vorticity fields were calculated. The results for (128) cubed simulations of this flow, and those obtained in recent experiments that analyzed 1- and 2-D intersections of atmospheric and laboratory flows, are in some agreement. A two-scale Cantor set model of the energy cascade process which describes the experimental results from 1-D intersections quite well, describes the 3-D results only marginally.

Deane, A. E.; Keefe, L. R.

1988-01-01

310

Techniques for classifying acoustic resonant spectra  

SciTech Connect

A second-generation nondestructive evaluation (NDE) system that discriminates between different types of chemical munitions is under development. The NDE system extracts features from the acoustic spectra of known munitions, builds templates from these features, and performs classification by comparing features extracted from an unknown munition to a template library. Improvements over first-generation feature extraction template construction and classification algorithms are reported. Results are presented on the performance of the system and a large data set collected from surrogate-filled munitions.

Roberts, R.S.; Lewis, P.S.; Chen, J.T.; Vela, O.A.

1995-12-31

311

Infrared absorption spectra, radiative efficiencies, and global warming potentials  

E-print Network

Infrared absorption spectra, radiative efficiencies, and global warming potentials of newly.mdpi.com/journal/atmosphere Article Infrared Absorption Spectra, Radiative Efficiencies, and Global Warming Potentials of Newly of 600­1730 cm-1 . These spectra are then used to calculate the radiative efficiencies and global warming

Wirosoetisno, Djoko

312

An atlas of optical spectra of white-dwarf stars  

Microsoft Academic Search

We present a complete atlas of optical spectra of white-dwarf stars. Spectra for all major spectral classes and subclasses are illustrated, and the variation of the dominant spectral features as a function of effective temperature and abundance is documented. We present, as well, spectra of several peculiar or rare types of degenerate stars.

F. Wesemael; J. L. Greenstein; James Liebert; R. Lamontagne; G. Fontaine; P. Bergeron; J. W. Glaspey

1993-01-01

313

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

314

Calculating Infrared Spectra of Proteins and Other Organic Molecules  

E-print Network

Calculating Infrared Spectra of Proteins and Other Organic Molecules Based on Normal Modes by Adam of this theoretical study of infrared spectra was to ascertain to what degree molecules may be identified from the NIST/EPA Gas-Phase Infrared Library. The calculated spectra of proteins, for which only force field

Thorpe, Michael

315

Uncovering the Weakest Absorbers in AGN Spectra  

NASA Astrophysics Data System (ADS)

The exquisite far-UV sensitivity of the Cosmic Origins Spectrograph has yielded moderate-resolution AGN spectra of unprecedented quality with signal to noise ratios (S/N) of 50 per resolution element in some cases. This high data quality allows us to detect some of the weakest (W 10 mÅ) absorption features ever found in far-UV spectra including weak photoionized Ly? forest absorbers at column densities N > 1012 cm-2 that may trace significant numbers of baryons in the form of ionized hydrogen, weak broad HI absorbers with b > 40 km/s that potentially trace warm collisionally ionized gas, and weak metal-line counterparts to Ly? absorbers in the intergalactic medium. However, accurately identifying and measuring weak astrophysical absorbers requires detailed knowledge of the spectrograph detectors and the latest in flat-fielding techniques. We present the results of both interactive and automated line searches in several of the highest-quality (S/N=30-50) extragalactic COS datasets taken to date. We catalog weak narrow lines, broad absorption features, and comment on the applicability of these techniques to the larger catalog of COS observations with more modest S/N.

Danforth, Charles; Stocke, J. T.; Shull, J. M.; Pieri, M.; Savage, B.; France, K.; Penton, S.; Keeney, B.

2011-01-01

316

Classification of infrared spectra from skin tumors  

NASA Astrophysics Data System (ADS)

The clinical differential diagnosis of skin tumors is an often-challenging task, to which the probing of skin with mid- and near-infrared (IR) light may be contributory. The development of objective methods for the analysis of IR spectra remains a major hurdle to developing clinically useful applications. The authors highlight different processing methods for IR spectra from skin biopsies and in-vivo skin tumors. Spectroscopic maps of biopsies of basal cell, squamous cell and melanocytic neoplasms were objectively grouped into distinct clusters that corresponded with tumor, epidermis, dermis, follicle and fat. Normal and abnormal skin components were located within maps using a search engine based upon linear discriminant analysis (LDA). In all instances, areas of tumor were distinct from normal tissue in biopsies. In-vivo, near-IR spectroscopy and LDA allowed discrimination between benign and malignant skin lesions with a high degree of accuracy. We conclude that IR spectroscopy has significant diagnostic promise in the skin cancer arena. The analytical methods described can now be used to create a powerful classification scheme in which to detect skin tumor cells within biopsied and living skin.

McIntosh, Laura M.; Mansfield, James R.; Crowson, A. Neil; Toole, John W. P.; Mantsch, Henry H.; Jackson, Michael

2000-05-01

317

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

318

Blind Source Separation For Ion Mobility Spectra  

NASA Astrophysics Data System (ADS)

Miniaturization is a powerful trend for smart chemical instrumentation in a diversity of applications. It is know that miniaturization in IMS leads to a degradation of the system characteristics. For the present work, we are interested in signal processing solutions to mitigate limitations introduced by limited drift tube length that basically involve a loss of chemical selectivity. While blind source separation techniques (BSS) are popular in other domains, their application for smart chemical instrumentation is limited. However, in some conditions, basically linearity, BSS may fully recover the concentration time evolution and the pure spectra with few underlying hypothesis. This is extremely helpful in conditions where non-expected chemical interferents may appear, or unwanted perturbations may pollute the spectra. SIMPLISMA has been advocated by Harrington et al. in several papers. However, more modern methods of BSS for bilinear decomposition with the restriction of positiveness have appeared in the last decade. In order to explore and compare the performances of those methods a series of experiments were performed.

Marco, S.; Pomareda, V.; Pardo, A.; Kessler, M.; Goebel, J.; Mueller, G.

2009-05-01

319

An atlas of selected calibrated stellar spectra  

NASA Technical Reports Server (NTRS)

Five hundred and fifty six stars in the IRAS PSC-2 that are suitable for stellar radiometric standards and are brighter than 1 Jy at 25 microns were identified. In addition, 123 stars that meet all of our criteria for calibration standards, but which lack a luminosity class were identified. An approach to absolute stellar calibration of broadband infrared filters based upon new models of Vega and Sirius due to Kurucz (1992) is presented. A general technique used to assemble continuous wide-band calibrated infrared spectra is described and an absolutely calibrated 1-35 micron spectrum of alpha(Tau) is constructed and the method using new and carefully designed observations is independently validated. The absolute calibration of the IRAS Low Resolution Spectrometer (LRS) database is investigated by comparing the observed spectrum of alpha(Tau) with that assumed in the original LRS calibration scheme. Neglect of the SiO fundamental band in alpha(Tau) has led to the presence of a specious 'emission' feature in all LRS spectra near 8.5 microns, and to an incorrect spectral slope between 8 and 12 microns. Finally, some of the properties of asteroids that effect their utility as calibration objects for the middle and far infrared region are examined. A technique to determine, from IRAS multiwaveband observations, the basic physical parameters needed by various asteroid thermal models that minimize the number of assumptions required is developed.

Walker, Russell G.; Cohen, Martin

1992-01-01

320

QSO'S with IPC X-Ray Spectra  

NASA Astrophysics Data System (ADS)

We propose to obtain both short and long wavelength ultraviolet spectrophotometry of 5 bright quasars that have well-determined x-ray spectra. Together with the quasars in our current IUE program and seven from the IUE data archive these objects will form the basis of a reasonably sized sample. For this sample we have in hand (or are in the process of obtaining) ground-based optical and infrared spectra and photometry and IRAS co-add data. Together these data define the quasars' continuum from ~100 microns to ~7 keV, (5 decades of frequency). The IUE data have particular importance for defining the optical-UV 'big bump' (accretion disk?) and the "300OA" 'small bump' due to Balmer continuum and FeII emission. The definition of these features is essential to the testing of the accretion disk hypothesis and particular disk models; the determination of the EUV ionizing spectrum, and the testing of the optically thick photoionization models.

Elvis, Martin S.

321

Nonlinear matter spectra in growing neutrino quintessence  

E-print Network

We investigate the nonlinear power spectra of density perturbations and acoustic oscillations in growing neutrino quintessence. In this scenario, the neutrino mass has a strong dependence on the quintessence field. The induced coupling stops the evolution of the field when the neutrinos become nonrelativistic, and triggers the transition to the accelerating phase of the cosmological expansion. At redshifts around five, the neutrino fluctuations are still linear and acoustic oscillations are present in the neutrino power spectrum, induced by the acoustic oscillations in the baryonic and dark-matter sectors. The neutrino perturbations become nonlinear at redshifts around three. The mode coupling generated by the nonlinearities erases the oscillations in the neutrino spectrum at some redshift above two. There is a potential danger that at later times the influence of the gravitational potentials induced by the neutrino inhomogeneities could erase the oscillations from the baryonic and dark-matter spectra, making the scenario incompatible with observations. For the scenario to be viable, the neutrino-induced gravitational potentials in the range of baryonic acoustic oscillations should not grow to average values much larger than 10^{-4}. The magnitude of the expected potentials is still not known reliably, as the process of structure formation is poorly understood in growing neutrino quintessence.

N. Brouzakis; V. Pettorino; N. Tetradis; C. Wetterich

2014-04-10

322

Satellite surface material composition from synthetic spectra  

NASA Astrophysics Data System (ADS)

The objective of this research was to determine if measurements from a Sagnac interferometer could provide reliable estimates of satellite material composition. The Sagnac interferometer yields a spatial interferogram that can be sampled by a linear detector array. The interferogram is related to the spectrum of the source through a Fourier transform. Here, spectral reflectivities of nine common satellite materials were used to simulate the spectrum on obtains from an ideal Sagnac interferometer in the beam-train of a ground-based telescope whose mission is to view satellites. The signal-to-noise ratio of the spectrum was varied to simulate the effect of range variation between the sensor and the satellite. The simulated spectra consisted of a linear mixture of spectra from two of the nine materials. Three different architectures were developed and their performances compared. One of the three architectures consisted of nine artificial neural networks (ANN's), one for each material, and a linear estimator that estimated the satellite surface area attributable to each material. This method estimates the material composition by using a classifier to identify the materials contributing to the mixture, then eliminating unlikely contributors to the mixture before performing a constrained linear estimate. It is shown that due to high classification errors, the system using solely a linear estimator provides the estimate with the lowest errors.

Caudill, Eugene L.

1994-12-01

323

Excitation Spectra of 1D Quantum Wires  

NASA Astrophysics Data System (ADS)

In this talk two different aspects of the excitation spectra of one dimensional (1D) semiconductor quantum wires will be discussed: (1) The nature of collective electronic excitations in 1D quantum wires; and (2) the band gap renormalization and excitonic effects in 1D quantum wires. In the first part, extensive theoretical results using the Bethe ansatz technique, the Lanczos' method, and the diagrammatic many-body theory will be presented for the spectral weight and the mode dispersion of the low-lying elementary electronic excitation spectra in 1D quantum wires with comparison to Raman Scattering experiments in GaAs quantum wires. Based on our detailed analytical and numerical results we conclude that the experimental observations are consistent with the existence of the collective charge density excitation mode, the collective spin density excitation mode, and a (low spectral weight) finite wave vector electron-hole single particle excitation mode (which arises from the finite curvature of the electron energy dispersion in the system). There is no evidence for a singlet spin density excitation mode in our calculations. In the second part, numerical solutions of the Bethe-Salpeter equation for interband excitonic transitions in 1D quantum wires will be presented. An approximate cancellation between self-energy and vertex correction effects is obtained in our calculations, providing an explaination for the experimental observation of an unshifted excitonic peak in highly excited 1D quantum wire lasers.

Wang, Daw-Wei

1998-03-01

324

IUE ultraviolet spectra of V Sagittae  

NASA Technical Reports Server (NTRS)

Ultraviolet spectra obtained by the IUE of the short-period, intrinsically variable, double-lined spectroscopic and eclipsing close binary V Sagittae are discussed. The 18 spectra measured between 1150 and 1950 A and 1850 and 3300 A over an interval of 179 days are shown to be dominated by emission features, with only Lyman alpha absorption apparent. Examination of the smooth continuum inferred for each spectrum results in a B-V color index of 0.20. The observed V magnitudes do not show a phase-locked or typical eclipsing light curve, due to intrinsic variability in the UV as well as the visible. The calibrated, reddening-corrected UV fluxes are used in an attempt to determine system temperature, but it is found that the continuum is most likely composite and variable, and thus a unique temperature assignment is impossible. The V Sge system is interpreted as possibly consisting of a primary early A, near-main-sequence star with an effective temperature of 10,000 K and a secondary thick, hot disk (temperature 17,000-300,000 K) embedding a white dwarf.

Koch, R. H.; Siah, M. J.; Fanelli, M. N.

1979-01-01

325

Analysis of the FF Aqr spectra  

NASA Astrophysics Data System (ADS)

We determine the atmospheric parameters of the secondary in the close binary system FF Aqr and analyze its chemical composition. A series of high-resolution spectra are taken at different orbital phases using the coude echelle spectrometer of the 1.5-m Russian-Turkish Telescope (RTT150). We show that the absorption line intensity of heavy elements varies with phase due to the spotty nature of the cool component. We determine the abundances of heavy elements in the star's atmosphere by modelling the synthetic spectra and performing a differential analysis of the chemical composition of FF Aqr relative to the solar composition. Our analysis of the averaged spectrum of FF Aqr yielded 539 abundance estimates for 21 chemical elements. We found the metallicity of the star ([ Fe/H] = -0.11 ± 0.08) to be close solar, in agreement with the hypothesis that FF Aqr should belong to the Galactic disk. The inferred chemical composition of the objects exhibits no anomalous abundances of the ?-, r-, and s-process elements like those earlier found in other systems (IN Com, LW Hya, V471 Tau). The lack of such anomalies in FF Aqr must be due to the fact that the elements heavier than 16 O cannot be synthesized in the core of the primary during the last stages of its evolution.

Shimanskaya, N. N.; Bikmaev, I. F.; Shimansky, V. V.

2011-07-01

326

SAMPI: Protein Identification with Mass Spectra Alignments  

PubMed Central

Background Mass spectrometry based peptide mass fingerprints (PMFs) offer a fast, efficient, and robust method for protein identification. A protein is digested (usually by trypsin) and its mass spectrum is compared to simulated spectra for protein sequences in a database. However, existing tools for analyzing PMFs often suffer from missing or heuristic analysis of the significance of search results and insufficient handling of missing and additional peaks. Results We present an unified framework for analyzing Peptide Mass Fingerprints that offers a number of advantages over existing methods: First, comparison of mass spectra is based on a scoring function that can be custom-designed for certain applications and explicitly takes missing and additional peaks into account. The method is able to simulate almost every additive scoring scheme. Second, we present an efficient deterministic method for assessing the significance of a protein hit, independent of the underlying scoring function and sequence database. We prove the applicability of our approach using biological mass spectrometry data and compare our results to the standard software Mascot. Conclusion The proposed framework for analyzing Peptide Mass Fingerprints shows performance comparable to Mascot on small peak lists. Introducing more noise peaks, we are able to keep identification rates at a similar level by using the flexibility introduced by scoring schemes. PMID:17386090

Kaltenbach, Hans-Michael; Wilke, Andreas; Böcker, Sebastian

2007-01-01

327

Spectra of Cas A's Highest Velocity Ejecta  

NASA Astrophysics Data System (ADS)

The young age and close distance of the Galactic supernova remnant Cassiopeia A (Cas A) make it perhaps our best case study and clearest look at the explosion dynamics of a core-collapse supernova (CCSN). Interestingly, Cas A exhibits two nearly opposing streams of high velocity ejecta or `jets' in its NE and SW regions racing outward at speeds more than twice that of the main shell. The nature of these jets, however, and their possible association with an aspherical supernova explosion mechanism is controversial. A handful of existing low-resolution spectra of outer knots in the NE jet display chemical abundances hinting at an origin from the S-Si-Ca- Ar rich layer deep inside the progenitor. If these abundances could be firmly established in both the NE and SW jets, it would be very strong evidence in support of a highly asymmetrical explosion engine for Cas A's progenitor and, in turn, for CCSNe in general. We request KPNO 4m telescope + MARS time to obtain high quality multi-object spectroscopy of Cas A's highest velocity ejecta to measure their nitrogen, sulfur, oxygen, calcium, and argon abundances. These spectra will be analyzed with the metal-rich shock models of J. Raymond and then compared to current sets of CCSN models paying particular attention to knot composition vs. ejection velocity and ejecta mixing.

Fesen, Robert A.; Milisavljevic, Dan

2010-08-01

328

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. PMID:22027200

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

329

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.

330

Supernova spectra below strong circumstellar interaction  

NASA Astrophysics Data System (ADS)

We construct spectra of supernovae (SNe) interacting strongly with a circumstellar medium (CSM) by adding SN templates, a black-body continuum, and an emission-line spectrum. In a Monte Carlo simulation we vary a large number of parameters, such as the SN type, brightness and phase, the strength of the CSM interaction, the extinction, and the signal to noise ratio (S/N) of the observed spectrum. We generate more than 800 spectra, distribute them to ten different human classifiers, and study how the different simulation parameters affect the appearance of the spectra and their classification. The SNe IIn showing some structure over the continuum were characterized as "SNe IInS" to allow for a better quantification. We demonstrate that the flux ratio of the underlying SN to the continuum fV is the single most important parameter determining whether a spectrum can be classified correctly. Other parameters, such as extinction, S/N, and the width and strength of the emission lines, do not play a significant role. Thermonuclear SNe get progressively classified as Ia-CSM, IInS, and IIn as fV decreases. The transition between Ia-CSM and IInS occurs at fV ~ 0.2-0.3. It is therefore possible to determine that SNe Ia-CSM are found at the (un-extincted) magnitude range -19.5 >M> -21.6, in very good agreement with observations, and that the faintest SN IIn that can hide a SN Ia has M = -20.1. The literature sample of SNe Ia-CSM shows an association with 91T-like SNe Ia. Our experiment does not support that this association can be attributed to a luminosity bias (91T-like being brighter than normal events). We therefore conclude that this association has real physical origins and we propose that 91T-like explosions result from single degenerate progenitors that are responsible for the CSM. Despite the spectroscopic similarities between SNe Ibc and SNe Ia, the number of misclassifications between these types was very small in our simulation and mostly at low S/N. Combined with the SN luminosity function needed to reproduce the observed SN Ia-CSM luminosities, it is unlikely that SNe Ibc constitute an important contaminant within this sample. We show how Type II spectra transition to IIn and how the H? profiles vary with fV. SNe IIn fainter than M = -17.2 are unable to mask SNe IIP brighter than M = -15. A more advanced simulation, including radiative transfer, shows that our simplified model is a good first order approximation. The spectra obtained are in good agreement with real data.

Leloudas, G.; Hsiao, E. Y.; Johansson, J.; Maeda, K.; Moriya, T. J.; Nordin, J.; Petrushevska, T.; Silverman, J. M.; Sollerman, J.; Stritzinger, M. D.; Taddia, F.; Xu, D.

2015-02-01

331

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.

332

HMBC-1,n-ADEQUATE spectra calculated from HMBC and 1,n-ADEQUATE spectra.  

PubMed

Unsymmetrical and generalized indirect covariance processing methods provide a means of mathematically combining pairs of 2D NMR spectra that share a common frequency domain to facilitate the extraction of correlation information. Previous reports have focused on the combination of HSQC spectra with 1,1-, 1,n-, and inverted (1)J(CC) 1,n-ADEQUATE spectra to afford carbon-carbon correlation spectra that allow the extraction of direct ((1)J(CC)), long-range ((n)J(CC), where n???2), and (1)J(CC)-edited long-range correlation data, respectively. Covariance processing of HMBC and 1,1-ADEQUATE spectra has also recently been reported, allowing convenient, high-sensitivity access to (n)J(CC) correlation data equivalent to the much lower sensitivity n,1-ADEQUATE experiment. Furthermore, HMBC-1,1-ADEQUATE correlations are observed in the F1 frequency domain at the intrinsic chemical shift of the (13)C resonance in question rather than at the double-quantum frequency of the pair of correlated carbons, as visualized by the n,1, and m,n-ADEQUATE experiments, greatly simplifying data interpretation. In an extension of previous work, the covariance processing of HMBC and 1,n-ADEQUATE spectra is now reported. The resulting HMBC-1,n-ADEQUATE spectrum affords long-range carbon-carbon correlation data equivalent to the very low sensitivity m,n-ADEQUATE experiment. In addition to the significantly higher sensitivity of the covariance calculated spectrum, correlations in the HMBC-1,n-ADEQUATE spectrum are again detected at the intrinsic (13)C chemical shifts of the correlated carbons rather than at the double-quantum frequency of the pair of correlated carbons. HMBC-1,n-ADEQUATE spectra can provide correlations ranging from diagonal ((0)J(CC) or diagonal correlations) to (4)J(CC) under normal circumstances to as much as (6)J(CC) in rare instances. The experiment affords the potential means of establishing the structures of severely proton-deficient molecules. PMID:23483673

Martin, Gary E; Blinov, Kirill A; Williamson, R Thomas

2013-05-01

333

Mineral Spectra from Nili Fossae, Mars  

NASA Technical Reports Server (NTRS)

Spectra collected by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) indicate the presence of three distinct minerals. The graphed information comes from an observation of terrain in the Nili Fossae area of northern Mars. CRISM is one of six science instruments on NASA's Mars Reconnaissance Orbiter.

Iron-magnesium smectite clay is formed through alteration of rocks by liquid water and is characterized by distinctive absorptions at 1.4, 1.9, and 2.3 micrometers due to water (H2O) and OH in the atomic structure of the mineral. Olivine is an iron magnesium silicate and primary igneous mineral, and water is not in its structure. Its spectrum is characterized by a strong and broad absorption at 1.0 micrometer due to ferrous iron (Fe2+). Carbonate is an alteration mineral identified by the distinctive paired absorptions at 2.3 and 2.5 micrometers. The precise band positions at 2.31 and 2.51 micrometers identify the carbonate at this location as magnesium carbonate. The broad 1.0 micrometer band indicates some small amount of ferrous iron is also present and the feature at 1.9 micrometers indicates the presence of water. CRISM researchers believe the magnesium carbonate found in the Nili Fossae region formed from alteration of olivine by water.

The data come from a CRISM image catalogued as FRT00003E12. The spectra shown here are five-pixel-by-five-pixel averages of CRISM L-detector spectra taken from three different areas within the image that have then been ratioed to a five-pixel-by-five-pixel common denominator spectrum taken from a spectrally unremarkable area with no distinctive mineralogic signatures. This technique highlights the spectral contrasts between regions due to their unique mineralogy. The spectral wavelengths near 2.0 micrometers are affected by atmospheric absorptions and have been removed for clarity.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, manages the Mars Reconnaissance Orbiter for the NASA Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The Johns Hopkins University Applied Physics Laboratory led the effort to build the CRISM instrument and operates CRISM in coordination with an international team of researchers from universities, government and the private sector.

2008-01-01

334

IIB soliton spectra with all fluxes activated  

NASA Astrophysics Data System (ADS)

Building upon an earlier proposal for the classification of fluxes, a sequence is proposed which generalizes the AHSS by computing type IIB string theory's group of conserved RR and also NS charges, which is conjectured to be a K-theory of dual pairs. As a test of this proposal, the formalism of Maldacena, Moore and Seiberg ( arxiv:hep-th/0108100) is applied to classify D-branes, NS5-branes, F-strings and their dielectric counterparts in IIB compactified on a 3-sphere with both NS and RR background fluxes. The soliton spectra on the 3-sphere are then compared with the output of the sequence, as is the baryon spectrum in Witten's non- spinc example, AdS 5× RP5. The group of conserved charges is seen to change during Brown-Teitelboim-like phase transitions which change the effective cosmological constant.

Evslin, Jarah

2003-05-01

335

Electroabsorption and electrophotoluminescence spectra of some subphthalocyanines  

NASA Astrophysics Data System (ADS)

Electric field effects on the electronically excited states have been investigated for two subphthalocyanines, F-SubPc and T-SubPc, which have the electron-withdrawing and electron-donating substituents, respectively. In contrast with T-SubPc, the directions of the electric dipole moment in the excited states S1 and S2 of F-SubPc are found to be very different from that in the ground state S0. The S1 and S2 states of T-SubPc show a prominent charge-transfer character, suggesting that T-SubPc is a suitable candidate as the dye in photovoltaic cells. Electrophotoluminescence spectra suggest that the intersystem crossing from S1 to T1 is enhanced by electric fields.

Awasthi, Kamlesh; Nakamura, Kosuke; Kono, Hirohiko; Kobayashi, Nagao; Ohta, Nobuhiro

2014-04-01

336

Spectra of Particulate Backscattering in Natural Waters  

NASA Technical Reports Server (NTRS)

Hyperspectral profiles of downwelling irradiance and upwelling radiance in natural waters (oligotrophic and mesotrophic) are combined with inverse radiative transfer to obtain high resolution spectra of the absorption coefficient (a) and the backscattering coefficient (bb) of the water and its constituents. The absorption coefficient at the mesotrophic station clearly shows spectral absorption features attributable to several phytoplankton pigments (Chlorophyll a, b, c, and Carotenoids). The backscattering shows only weak spectral features and can be well represented by a power-law variation with wavelength (lambda): b(sub b) approx. Lambda(sup -n), where n is a constant between 0.4 and 1.0. However, the weak spectral features in b(sub b), suggest that it is depressed in spectral regions of strong particle absorption. The applicability of the present inverse radiative transfer algorithm, which omits the influence of Raman scattering, is limited to lambda < 490 nm in oligotrophic waters and lambda < 575 nm in mesotrophic waters.

Gordon, Howard, R.; Lewis, Marlon R.; McLean, Scott D.; Twardowski, Michael S.; Freeman, Scott A.; Voss, Kenneth J.; Boynton, Chris G.

2009-01-01

337

On Magnetic Spectra of Earth and Mars  

NASA Technical Reports Server (NTRS)

The spectral method for distinguishing crustal from core-source magnetic fields is reexamined, modified, and applied to both a comprehensive geomagnetic field model and an altitude normalized magnetic map of Mars. The observational spectra are fairly fitted by theoretical forms expected from certain elementary classes of magnetic sources. For Earth we find fields from a core of radius 3512 +/- 64 km, in accord with the seismologic core radius of 3480 km, and a crust represented by a shell of random dipolar sources at radius 6367 +/- 14 km, near the planetary mean radius of 6371.2 km. For Mars we find no sign of a core-source field, only a field from a crust represented in same way, but at radius 3344 +/- 10 km, about 46 km below the planetary mean radius of 3389.5 km, and with sources about 9.6 +/- 3.2 times stronger.

Voorhies, C. V.; Sabaka, T. J.; Purucker, M.

2002-01-01

338

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

339

Jets and Bombs: Characterizing IRIS Spectra  

NASA Astrophysics Data System (ADS)

For almost two decades, SUMER has provided an unique perspective on explosive events in the lower solar atmosphere. One of the hallmark observations during this tenure is the identification of quiet sun bi-directional jets in the lower transition region. We investigate these events through two distinct avenues of study: a MHD model for reconnection and the new datasets of the Interface Region Imaging Spectrograph (IRIS). Based on forward modeling optically thin spectral profiles, we find the spectral signatures of reconnection can vary dramatically based on viewing angle and altitude. We look to the IRIS data to provide a more complete context of the chromospheric and coronal environment during these dynamic events. During a joint IRIS-SUMER observing campaign, we observed spectra of multiple jets, a small C flare, and an Ellerman bomb event. We discuss the questions that arise from the inspection of these new data.

Schmit, Donald; Innes, Davina

2014-06-01

340

Resonance spectra of caged black holes  

NASA Astrophysics Data System (ADS)

Recent numerical studies of the coupled Einstein-Klein-Gordon system in a cavity have provided compelling evidence that confined scalar fields generically collapse to form black holes. Motivated by this intriguing discovery, we here use analytical tools in order to study the characteristic resonance spectra of the confined fields. These discrete resonant frequencies are expected to dominate the late-time dynamics of the coupled black-hole-field-cage system. We consider caged Reissner-Nordström black holes whose confining mirrors are placed in the near-horizon region (here is the radius of the confining mirror and are the radii of the black-hole horizons). We obtain a simple analytical expression for the fundamental quasinormal resonances of the coupled black-hole-field-cage system: , where is the temperature of the caged black hole and is the resonance parameter.

Hod, Shahar

2014-11-01

341

Measuring Reddening with SDSS Stellar Spectra  

NASA Astrophysics Data System (ADS)

We present measurements of dust reddening using the colors of stars with spectra in the Sloan Digital Sky Survey. We measure reddening as the difference between the measured colors of a star and the predicted colors, as derived from stellar parameters from the SEGUE Stellar Parameter Pipeline. We achieve uncertainties of 54, 34, 25, and 28 mmag in the colors u-g, g-r, r-i, and i-z, per star, though the uncertainty varies depending on the stellar type and the magnitude of the star. The spectrum-based reddening measurements confirm our earlier "blue tip" reddening measurements, preferring an RV = 3.1 Fitzpatrick (1999) reddening law to O'Donnell (1994) or Cardelli et al. (1989) reddening laws. We obtain a reddening law normalization within 4% of the blue tip results, despite the somewhat different sky footprint used in the two analyses.

Schlafly, Eddie; Finkbeiner, D. P.

2011-01-01

342

Raman spectra of carbon nanotubes with monovacancy  

NASA Astrophysics Data System (ADS)

By using the empirical Brenner potential, we have calculated the structural and vibrational properties of single walled carbon nanotubes (SWCNTs) with monovacancy, based upon which their nonresonant Raman spectra have been calculated by the empirical bond polarizability model. It is found that a new pentagon ring coupling with a dangling bond will form in the SWCNTs with monovacancy and the structural stability is responsible for the orientation of the new bond comparing with the tube axis. More importantly, it is found that the monovacancy-induced Raman peaks lie out of the SWCNT's G-band and can be considered as the intrinsic characteristic of the SWCNTs with monovacancy, which can be used to detect the monovacancy experimentally.

Chang, Xu; Feng, Cuidi; Fa, Wei; Chen, Wencong

2013-12-01

343

A Study of Pioneer Venus Nightglow Spectra  

NASA Technical Reports Server (NTRS)

The work performed during the 12-month period of this contract involved: (1) further analysis of latitudinal variations in the Venusian NO nightglow intensity from PVOUVS data; (2) corrections made to the input data for the VTGCM model, relating specifically to a factor of three increase in the three-body recombination rate coefficient of N + O; (3) consideration of limits on the rate of reaction of N-atoms with CO2; (4) consideration of the Venusian equivalent of the terrestrial hot N-atom reaction for NO production; and (5) successful location of video images of meteor trails from space, for the purpose of making a comparison with the meteor trail that we have hypothesized as an explanation of intense UV spectra observed on a particular Pioneer Venus (PV) orbit.

Slanger, Tom G.

1993-01-01

344

Features of the NCth in SEE spectra  

NASA Astrophysics Data System (ADS)

Basing on experiments carried out at the Sura heating facility it has been elaborated an empirical model for generation of the thermal narrow continuum NC th in stimulated electromagnetic emission SEE spectra which is observed in the lower sideband of the pump wave PW frequency extending up to the down-shifted maximum DM and the spectral intensity of which decreases exponentially with the increase of frequency shift from the pump The generation of NC th as well as DM and broad continuum BC occurs due to excitation of the thermal resonance parametric instability TPI Integral intensity of the NC th is close to or even higher than DM integral intensity The basic characteristics of the NC th are very similar to analogous DM ones Among them are magnitudes of their thresholds strong influence of HF-induced striations on their features dependences of their intensity on PW frequency PW power and heating antenna beam position relatively to the geomagnetic field gyro features typical times of their development after PW switch-on generation of these SEE components when a PW frequency is slightly below of F 2 -region critical frequency f 0F2 but an upper hybrid resonance frequency for the PW still remains below f 0F2 The intensity of the NC th as for DM has a maximal level in a PW frequency range from 5 to 7 MHz and it is fast reduced outside of this range The form of NC th spectra is often very similar to the spectral form of DM and its satellites DM1 and DM2 for their low frequency flanks

Frolov, V. L.; Nedzvetski, D. I.; Sergeev, E. N.

345

Spectra of small Koronis family members  

NASA Astrophysics Data System (ADS)

The space-weathering process and its implications for the relationships between S- and Q-type asteroids and ordinary chondrite meteorites are long-standing problems in asteroid science. Although the visible and near-infrared spectra of S- and Q-type objects qualitatively show the same absorption features and quantitatively show evidence of the same minerals, the S types display increased spectral slopes and muted absorption features compared to the Q types. This spectral mismatch is consistent with the effects of the space weathering process. Binzel et al. provided the missing link between Q- and S-type bodies in near-Earth space by showing a reddening of spectral slope in objects from 0.1 to 5 km that corresponded to the transition from Q- to S-type spectra. This result implied that size, and therefore age, is related to the relationship between Q- and S-type. The existence of Q-type objects in the main belt was not confirmed until Mothe-Diniz and Nesvorny (2008) found them in young S-type clusters. To investigate the trend from Q to S in the main belt, we examined space weathering within the old main-belt Koronis family using a spectrophotometric survey (Rivkin et al. 2011, Thomas et al. 2011). Rivkin et al. (2011) identified several potential Q-type objects within the Koronis family. Our Q-type candidates were identified using broad-band spectrophotometry and could not be taxonomically classified on that basis alone. We obtained follow-up visible and near-infrared spectral observations of our potential Q-type objects, (26970) Elias, (45610) 2000 DJ_{48}, and (37411) 2001 XF_{152}, using Gemini and Magellan. We will present the results of these spectral follow-up observations. Observations of (26970) Elias demonstrate that the object is more consistent with the average Q-type spectrum than the average S-type spectrum.

Thomas, C.; Rivkin, A.; Trilling, D.; Moskovitz, N.

2014-07-01

346

HF Accelerated Electron Fluxes, Spectra, and Ionization  

NASA Astrophysics Data System (ADS)

Wave particle interactions, an essential aspect of laboratory, terrestrial, and astrophysical plasmas, have been studied for decades by transmitting high power HF radio waves into Earth's weakly ionized space plasma, to use it as a laboratory without walls. Application to HF electron acceleration remains an active area of research (Gurevich in Usp Fizicheskikh Nauk 177(11):1145-1177, 2007) today. HF electron acceleration studies began when plasma line observations proved (Carlson et al. in J Atmos Terr Phys 44:1089-1100, 1982) that high power HF radio wave-excited processes accelerated electrons not to ~eV, but instead to -100 times thermal energy (10 s of eV), as a consequence of inelastic collision effects on electron transport. Gurevich et al (J Atmos Terr Phys 47:1057-1070, 1985) quantified the theory of this transport effect. Merging experiment with theory in plasma physics and aeronomy, enabled prediction (Carlson in Adv Space Res 13:1015-1024, 1993) of creating artificial ionospheres once ~GW HF effective radiated power could be achieved. Eventual confirmation of this prediction (Pedersen et al. in Geophys Res Lett 36:L18107, 2009; Pedersen et al. in Geophys Res Lett 37:L02106, 2010; Blagoveshchenskaya et al. in Ann Geophys 27:131-145, 2009) sparked renewed interest in optical inversion to estimate electron spectra in terrestrial (Hysell et al. in J Geophys Res Space Phys 119:2038-2045, 2014) and planetary (Simon et al. in Ann Geophys 29:187-195, 2011) atmospheres. Here we present our unpublished optical data, which combined with our modeling, lead to conclusions that should meaningfully improve future estimates of the spectrum of HF accelerated electron fluxes. Photometric imaging data can significantly improve detection of emissions near ionization threshold, and confirm depth of penetration of accelerated electrons many km below the excitation altitude. Comparing observed to modeled emission altitude shows future experiments need electron density profiles to derive more accurate HF electron flux spectra.

Carlson, Herbert C.; Jensen, Joseph B.

2014-12-01

347

Efficient Subclassification of Type Ia Supernova Spectra  

NASA Astrophysics Data System (ADS)

Before 1991, no subclassification of Type Ia supernova spectra was in use. After the appearance of the strikingly peculiar SN 1991T and SN 1991bg, SN Ia spectra usually were just said to be normal, or SN 1991T-like, or SN 1991bg-like. Eventually a few quantitative spectroscopic parameters were introduced, e.g., (1) v10(Si II), the blueshift at 10 days after maximum light of the strong Si II absorption feature near 6100 Å (Branch & van den Bergh 1993); (2) R(Si II), the ratio of the depths of Si II absorption features near 5750 Å and 6100 Å (Nugent et al. 1995); (3) v-dot, the rate at which the blueshift of the 6100 Å absorption decreases during postmaximum epochs (Benetti et al. 2005), and (4) EWw{Si II}, the equivalent width of a Si II absorption feature near 4000 Å (Arsenijevic et al. 2008). These parameters have their uses, but studies of SNe Ia have shown that the spectroscopic diversity is multidimensional, so no single spectroscopic parameter can provide a fully adequate subclassification. We examine the efficacy of a two parameter classification based on the equivalent widths of the 5750 Å and 6100 Å absorptions. We propose a notation that includes these parameters, for example, SN 2002bf (BL/11/175), where BL denotes "broad lines", one of the four spectroscopic groups introduced by Branch (2006), and 11 and 175 are the 5750 Å and 6100 Å equivalent widths. Such a purely spectroscopic subclassification, based on a single spectrum obtained within a few days of maximum light, would concisely convey useful information about SN 2002bf much as a spectral type of B2 IV concisely conveys information about Acrux.

Dang, Leeann; Branch, D.; Baron, E.

2009-01-01

348

CO2 profile retrievals from TCCON spectra  

NASA Astrophysics Data System (ADS)

The Total Carbon Column Observing Network (TCCON) is a global network of ground-based Fourier Transform Spectrometers recording direct solar spectra in the near-infrared spectral region. With stringent requirements on the instrumentation, data processing and calibration, accurate and precise column-averaged abundances of CO2, CH4, N2O, HF, CO, H2O, and HDO are retrieved being an essential contribution for the validation of satellite data (e.g. GOSAT, OCO-2) and carbon cycle research (Olsen and Randerson, 2004). However, the determined column-averaged dry air mole fraction (DMF) contains no information about the vertical CO2 profile, due to the use of a simple scaling retrieval within the common TCCON analysis, where the fitting algorithm GFIT (e.g. Yang et al., 2005) is used. In this presentation we will apply a different procedure for calculating trace gas abundances from the measured spectra, the fitting algorithm PROFFIT (Hase et. al., 2004) which has been shown to be in very good accordance with GFIT. PROFFIT additionally offers the ability to perform profile retrievals in which the pressure broadening effect of absorption lines is used to retrieve vertical gas profiles, being of great interest especially for the CO2 modelling community. A new analyzing procedure will be shown and retrieved vertical CO2 profiles of the TCCON sites Izaña (Tenerife, Canary Islands, Spain) and Lamont (Oklahoma, USA) will be presented and compared with simultaneously performed surface in-situ measurements and CO2 profiles from different aircraft campaigns. References: - Hase, F. et al., J.Q.S.R.T. 87, 25-52, 2004. - Olsen, S.C. and Randerson, J.T., J.G.Res., 109, D023012, 2004. - Yang, Z. et al., J.Q.S.R.T., 90, 309-321, 2005.

Dohe, Susanne; Hase, Frank; Sepúlveda, Eliezer; García, Omaira; Wunch, Debra; Wennberg, Paul; Gómez-Peláez, Angel; Abshire, James B.; Wofsy, Steven C.; Schneider, Matthias; Blumenstock, Thomas

2014-05-01

349

Spectra of volcanic rocks glasses as analogues of Mercury surface spectra  

NASA Astrophysics Data System (ADS)

Remote-sensing studies have revealed that most of the inner planets surfaces are composed by magmatic effusive rocks as lava flows or pyroclastic deposits, that are the natural products of magma-rock dynamic systems controlled by T, P, oxygen fugacity and time. These materials generally contain a fair amount of volcanic glass, due to the magma rapid cooling once effused on the surface. The VNIR reflectance spectroscopy is one of the most relevant tools for remote-sensing studies and in the last decades gave important results identifying the presence of different Fe-Mg silicates, such as olivine and pyroxenes, on the planets surfaces. However, the mineralogical interpretation of the observed spectral features of several volcanic areas on the inner Solar System bodies is still matter of debate. In particular the presence of dark volcanic glass, which can dominate or not the rock texture, influences the spectra signatures. In fact samples with a glass-bearing groundmass have lower albedo and reduced band intensity of the spectra of samples with comparable mineral composition and intergranular texture. As a consequence, an important goal for studying the planetary crusts is to understand the spectral behavior of volcanic material, where chemical or physical parameters are different depending on geologic context and effusive processes. We present here preliminary laboratory activity to investigate VNIR reflectance spectra of several volcanic glasses. Reflectance spectra, in the wavelength range between 0.35- 2.50 ?m, are measured on powders of magmatic rocks, having different composition and textures, at fine (<60 ?m in diameter) and very fine (<10 ?m) grain sizes. For each rock sample a corresponding “thermal shocked-sample” is produced by heating at 1300°C and P=1 atm and a glass-sample was produced by melting at 1500°C and P=1 atm, than quenching it in air. Reflectance spectra of powders of shocked and glass-samples were acquired at the same grain size, and compared with rock-powder spectra. This laboratory activity is in support of the SIMBIO-SYS/VIHI imaging spectrometer aboard the future ESA mission to Mercury and is financially supported by an ASI grant.

Carli, C.; Capaccioni, F.; de Sanctis, M.; Filacchione, G.; Sgavetti, M.; di Genova, D.; Vona, A.; Visonà, D.; Ammannito, E.

2010-12-01

350

Monte Carlo simulation of Auger-electron spectra.  

PubMed

A procedure to calculate the complex spectra of electron-capture nuclides which simultaneously eject several electrons and X-rays with different energies is presented. The model is applied to compute spectra of the radionuclides (125)I, (123)I and (111)In. The spectra are then compared with experimental spectra obtained by means of liquid scintillation counting. To this end, the computed spectra were transformed to allow for the nonlinear response function for a liquid scintillator, chemical quenching, as well as the Wallac-type amplifier used for the measurements. The calculated spectra are important for applications of free parameter models in liquid scintillation counting and also for studying the impact of electron-capture nuclides on DNA. PMID:19013824

Grau Carles, A; Kossert, K

2009-01-01

351

Simulation of dielectric spectra of erythrocytes with various shapes  

NASA Astrophysics Data System (ADS)

Dielectric spectra of erythrocyte suspensions were numerically simulated over a frequency range from 1 kHz to 100 MHz to study the effects of erythrocyte shape on the dielectric spectra. First, a biconcave-discoid model for normal erythrocytes or discocytes was compared with an equivalent oblate spheroid model. The two models showed similar dielectric spectra to each other, suggesting that the oblate spheroid model can be approximately used for discocytes. Second, dielectric spectra were simulated for discocytes deformed by osmotic cell swelling. The deformation resulted in the increase in relaxation intensity and the sharpening of spectrum shape. Finally, dielectric spectra were simulated for echinocytes, stomatocytes and sickle cells that are induced by chemical agents and diseases. The dielectric spectra of echinocytes and stomatocytes were similar to each other, being distinguishable from that of discocytes and quite different from that of sickle cells.

Asami, Koji

2009-07-01

352

Spectra of volcanic rocks glasses as analogues of Mercury surface spectra  

NASA Astrophysics Data System (ADS)

Remote-sensing studies have revealed that most of the inner planets surfaces are covered by magmatic effusive rocks, that are the natural products of magma-rock dynamic systems controlled by T, P, oxygen fugacity and time, as lava flows or pyroclastic deposits. These materials generally contain a fair amount of volcanic glass, due to the magma rapid cooling once effused on the surface. Volcanic glass can dominate or not the rock texture. The VNIR reflectance spectroscopy is one of the most important methods for remote-sensing studies and in the last decades gave important results identifying the presence of different Fe-Mg silicates, such as olivine and pyroxenes, on the planets surfaces. However, the mineralogical interpretation of the observed spectral features of several volcanic areas on the inner Solar System bodies is still matter of debate. As a consequence, an important goal for studying the planetary crusts is to understand the spectral behavior of volcanic material produced by different volcanic systems, where chemical or physical parameters are different. We present here preliminary laboratory activity to investigate in the VNIR reflectance spectra the different behaviors of volcanic glasses. Reflectance spectra, in the range of wavelength between 350-2500 nm, were measured on powders of magmatic rocks, with different composition and textures, at fine (<0.06 mm) and very fine (<0.01 mm) grain sizes. For each rock sample a corresponding glass-sample was produced by melting at 1300°C and P=1atm, than quenching it in water. Reflectance spectra of powders of glass-samples were acquired at the same grain size, and compared with rock-powder spectra.

Carli, Cristian; Capaccioni, Fabrizio; de Sanctis, Maria Cristina; Filacchione, Gianrico; Sgavetti, Maria; Visonà, Dario; Nestola, Fabrizio; Ammannito, Eleonora

2010-05-01

353

Separation of overlapping spectra from evolving systems using factor analysis. 4. Fluorescence spectra of hematoporphyrin IX.  

PubMed

Fluorescence spectra of hematoporphyrin IX (Hp) in water and in aqueous SDS solutions are obtained in the pH range 0.1 to 13 to determine the ionisation state of the molecule as a function of pH. In water, the spectra are complicated by aggregation which is quite severe near pH 4. In aqueous SDS, the aggregation is much less violent. Factor analysis (FA) is used to identify five species in the fluorescence spectra in each series of solutions. The distribution curve of these species as a function of pH is also obtained. By comparing the spectra and the distribution curve of Hp with those of HPPEEA, an ethanolamide derivative of Hp that does not contain the carboxylic groups (Part 3), the species are identified. For Hp in water we have obtained the following species: the dication in two allotropic forms in the pH range 0 to 5; the monocation (with the charge on an imino nitrogen) in the pH range 2 to 7; and the free base in the pH range 3.5 to 13. The monocation observed by the second derivative technique revealed three subspecies. For Hp in aqueous SDS we have obtained the following species; one dication in the pH range 0 to near 4; one monocation (with the charge on an imino nitrogen) in the pH range 0.5 to 9; three free bases (with no charge on the imino nitrogen) in the pH range 4 to 13. Of the latter, one species is the neutral molecule, another is a dianion (with the charges on the carboxylic side chains), and the third one appearing at pH higher than 10 is an allotropic form of the dianion. PMID:7626746

Chapados, C; Girard, D; Trudel, M; Ringuet, M

1995-08-01

354

Resonant Compton scattering and gamma-ray burst continuum spectra  

NASA Technical Reports Server (NTRS)

The Thomson limit of resonant inverse Compton scattering in the strong magnetic fields of neutron stars is considered as a mechanism for producing gamma-ray burst continuum spectra. Photon production spectra and electron cooling rates are presented using the full magnetic Thomson cross-section. Model emission spectra are obtained as self-consistent solutions of a set of photon and electron kinetic equations, displaying spectral breaks and other structure at gamma-ray energies.

Baring, M. G.

1995-01-01

355

Orthogonal signal correction of near-infrared spectra  

Microsoft Academic Search

Near-infrared (NIR) spectra are often pre-processed in order to remove systematic noise such as base-line variation and multiplicative scatter effects. This is done by differentiating the spectra to first or second derivatives, by multiplicative signal correction (MSC), or by similar mathematical filtering methods. This pre-processing may, however, also remove information from the spectra regarding Y (the measured response variable in

Svante Wold; Henrik Antti; Fredrik Lindgren; Jerker Öhman

1998-01-01

356

Broadband acoustic spectra of aqueous solutions of human serum albumin  

Microsoft Academic Search

Between 0.2 and 2000 MHz, sonic absorption spectra of solutions of albumin in water and in aqueous phosphate buffer systems have been measured at different temperatures (15-35 C), pH values (1.8-12.3), and protein concentrations (0.2-4% w\\/w). Broad absorption spectra, indicating the presence of various relaxation processes, have been found. Depending on the albumin concentration, the spectra can be analytically represented

T. Hushcha; A. Peytcheva; U. Kaatze

2002-01-01

357

Composite Quasar Spectra from the Sloan Digital Sky Survey  

Microsoft Academic Search

We have created a variety of composite quasar spectra using a homogeneous data set of over 2200 spectra from the Sloan Digital Sky Survey (SDSS). The quasar sample spans a redshift range of 0.044<=z<=4.789 and an absolute r' magnitude range of -18.0 to -26.5. The input spectra cover an observed wavelength range of 3800-9200 Å at a resolution of 1800.

Daniel E. Vanden Berk; Gordon T. Richards; Amanda Bauer; Donald P. Schneider; Timothy M. Heckman; Donald G. York; Patrick B. Hall; Xiaohui Fan; Scott F. Anderson; James Annis; Neta A. Bahcall; Mariangela Bernardi; John W. Briggs; J. Brinkmann; Robert Brunner; Scott Burles; Larry Carey; Francisco J. Castander; A. J. Connolly; J. H. Crocker; István Csabai; Mamoru Doi; Douglas Finkbeiner; Scott Friedman; Joshua A. Frieman; Masataka Fukugita; James E. Gunn; Zeljko Ivezic; Stephen Kent; Peter Z. Kunszt; D. Q. Lamb; R. French Leger; Daniel C. Long; Jon Loveday; Robert H. Lupton; Avery Meiksin; Aronne Merelli; Heidi Jo Newberg; Matt Newcomb; Russell Owen; Jeffrey R. Pier; Adrian Pope; Constance M. Rockosi; David J. Schlegel; Walter A. Siegmund; Stephen Smee; Yehuda Snir; Chris Stoughton; Christopher Stubbs; Mark SubbaRao; Alexander S. Szalay; Gyula P. Szokoly; Christy Tremonti; Alan Uomoto; Patrick Waddell; Brian Yanny; Wei Zheng

2001-01-01

358

Problems in abundance determination from UV spectra of hot supergiants  

NASA Astrophysics Data System (ADS)

We present measurements of equivalent widths of the UV, presumably photospheric lines: C III 1247 Å, N III 1748 Å, N III 1752 Å, N IV 1718 Å and He II 1640 Å in high-resolution IUE spectra of 24 galactic OB supergiants. Equivalent widths measured from the observed spectra have been compared with their counterparts in the Tlusty NLTE synthetic spectra. We discuss possibilities of static plan-parallel model to reproduce observed UV spectra of hot massive stars and possible reasons why observations differ from the model so much.

Dekovi?, M. Sarta; Kotnik-Karuza, D.; Jurki?, T.; Prester, D. Dominis

2010-03-01

359

[Studies on CD spectra of derivatives of shikonin and alkannin].  

PubMed

The circular dichroism (CD) and electronic absorption spectra of seven derivatives of shikonin and alkannin isolated from the roots of Onosma confertum W.W. Smith (from Sichuan) and Arnebia euchroma (Royle) Johust (from Xinjiang) were described. Each pair of CD spectra obtained was exact mirror images and the UV spectra of these compounds were very similar. In comparison with the CD spectra of shikonin given in literature, the configuration of the pigments from Sichuan was assigned R and from Xinjiang were all S. PMID:8213171

Ai, K H; Jin, J; Liu, H

1993-01-01

360

Synthetic infrared spectra for correlation spectroscopy  

SciTech Connect

As a first step toward the development of a new remote sensing technique that the authors call holographic correlation spectroscopy, they demonstrate that diffractive optics can be used to synthesize the infrared spectra of real compounds. In particular, they have designed, fabricated, and characterized a diffractive element that successfully reproduces the major features f the spectrum of gaseous HF in the region between 3,600 cm{sup {minus}1} and 4,300 cm{sup {minus}1}. The reflection-mode diffractive optic consists of 4,096 lines, each 4.5 {micro}m wide, at 16 discrete depths relative to the substrate (from 0 to 1.2 {micro}m), and was fabricated on a silicon wafer using anisotropic reactive ion-beam etching in a four-mask-level process. The authors envision the use of diffractive elements of this type to replace the cumbersome reference cells of conventional correlation spectroscopy and thereby enable a new class of compact and versatile correlation spectrometers.

Sinclair, M.B.; Butler, M.A.; Ricco, A.J.; Kravitz, S.H.; Zubrzycki, W.J.; Warren, M.E.

1997-12-01

361

Understanding Vibrational Spectra of Silicon Nanocrystals  

NASA Astrophysics Data System (ADS)

After the discovery of light emission from porous Si, nanostructured Si became a promising material for opto-electronic applications. For two decades lots of both experimental and theoretical works done in order to understand mechanisms behind the interaction of light with low dimensional forms of Si. In this work we employed MD simulation technique. The simulation details are similar to our earlier work except we used Large Scale Atomistic Molecular Modeling Package Software (LAMMPS) with ReaxFF package as an integrator. We used constant pressure constant temperature (NPT) ensemble with a simulation box size around 4.2 nm. We inserted silicon nanocrystals into amorphous silicon dioxide matrix with diameter ranging from 2 nm to 3.2 nm using a scheme defined in our previous work7. We also simulated free standing hydrogen passivated nanocrystals with same diameters to compare effects of oxide matrix on the nanocrystals. The effect of strain on vibrational spectra of Silicon Nanocrystals is studied as a function of nanocrystal diameter using reactive molecular dynamics simulations technique for both embedded and hydrogen passivated nanocrystals. With use of refined parameters our calculations reproduce the redshift of the Raman active transverse optical peak of Si-Si vibrations with decreasing the nanocrystal size.

Yilmaz, Dundar; Sevik, Cem; Bulutay, Ceyhun; Cagin, Tahir

2011-03-01

362

BHXRB accretion disks: spectra too soft?  

NASA Astrophysics Data System (ADS)

In case of almost every black-hole X-ray binary where BH spin has been estimated using the method of fitting of X-ray continuum, the result shows a drop of the estimated spin with increasing luminosity after luminosity exceeds a treshold value of ~0.3 Eddington. This tells us that the accretion disk model that has been used (Novikov-Thorne thin disk) starts to have difficulties to accurately describe the real disk spectra, which are significantly softer than the one predicted by the model. However, it is not only the disk model which shapes the final spectrum. Equally important is the spectral hardening predicted by disk atmosphere models (e.g. BHSPEC). The talk will summarize processes that modify emergent spectrum of thermal disks and depart it from being blackbody. It will show the local (at each place in the disk) and global (after integration over the disk) spectral hardening factor, its dependence on luminosity and alpha-viscosity and implications for spectral fittings.

Bursa, Michal

2012-07-01

363

Inflationary power spectra with quantum holonomy corrections  

NASA Astrophysics Data System (ADS)

In this paper we study slow-roll inflation with holonomy corrections from loop quantum cosmology. It was previously shown that, in the Planck epoch, these corrections lead to such effects as singularity avoidance, metric signature change and a state of silence. Here, we consider holonomy corrections affecting the phase of cosmic inflation, which takes place away from the Planck epoch. Both tensor and scalar power spectra of primordial inflationary perturbations are computed up to the first order in slow-roll parameters and V/?c, where V is a potential of the scalar field and ?c is a critical energy density (expected to be of the order of the Planck energy density). Possible normalizations of modes at short scales are discussed. In case the normalization is performed with use of the Wronskian condition applied to adiabatic vacuum, the tensor and scalar spectral indices are not quantum corrected in the leading order. However, by choosing an alternative method of normalization one can obtain quantum corrections in the leading order. Furthermore, we show that the holonomy-corrected equations of motion for tensor and scalar modes can be derived based on effective background metrics. This allows us to show that the classical Wronskian normalization condition is well defined for the cosmological perturbations with holonomy corrections.

Mielczarek, Jakub

2014-03-01

364

Spectra as windows into exoplanet atmospheres  

PubMed Central

Understanding a planet’s atmosphere is a necessary condition for understanding not only the planet itself, but also its formation, structure, evolution, and habitability. This requirement puts a premium on obtaining spectra and developing credible interpretative tools with which to retrieve vital planetary information. However, for exoplanets, these twin goals are far from being realized. In this paper, I provide a personal perspective on exoplanet theory and remote sensing via photometry and low-resolution spectroscopy. Although not a review in any sense, this paper highlights the limitations in our knowledge of compositions, thermal profiles, and the effects of stellar irradiation, focusing on, but not restricted to, transiting giant planets. I suggest that the true function of the recent past of exoplanet atmospheric research has been not to constrain planet properties for all time, but to train a new generation of scientists who, by rapid trial and error, are fast establishing a solid future foundation for a robust science of exoplanets. PMID:24613929

Burrows, Adam S.

2014-01-01

365

Raman spectra of pigmented skin conditions  

NASA Astrophysics Data System (ADS)

Melanoma is the most aggressive skin cancer and is invariably fatal if left untreated. Melanoma removal at early stages is almost always curative and therefore early detection is essential. Removal of every pigmented lesion is unacceptable for the patient, especially in the case of multiple skin lesions or lesions localized in cosmetically important parts of the body such as the face because of risk of scarring. The development of a technique to detect these changes in a noninvasive way is therefore crucial for melanoma detection. In this study, we have used FT-Raman Spectroscopy to investigate through PCA analysis the alterations in the molecular structure of 90 skin spectra, being 30 Pigmented Nevi, 30 Primary Melanoma, and 30 Metastasis, for 6 patients. For projection of data, the scores (Principal Components) PC1 to PC3 were calculated. PC1 versus PC3 for the 800 to 1800 cm -1 spectral region. PC1 versus PC2 for the 1200 to 1400 cm -1 spectral region. In both analysis, we could differentiate the three different types of tissues.

Bitar, Renata; Moreno, Marcelo; Oliveira, Andréa; Cartaxo, Sidney; Martinho, Herculano; Espírito Santo, Ana Maria do; Santos, Ivan Dunshee; Ferreira, Lydia Massako; Martin, Airton

2007-02-01

366

Moment Magnitude Calibration for the Eastern Mediterranean Region from Broadband Regional Coda Envelopes  

SciTech Connect

The following is an overview of results from ROA01-32 that focuses on an empirical method of calibrating stable seismic source moment-rate spectra derived from regional coda envelopes using broadband stations. The main goal was to develop a regional magnitude methodology that had the following properties: (1) it is tied to an absolute scale and is thus unbiased and transportable; (2) it can be tied seamlessly to the well-established teleseismic and regional catalogs; (3) it is applicable to small events using a sparse network of regional stations; (4) it is flexible enough to utilize S{sub n}-coda, L{sub g}-coda, or P-coda, whichever phase has the best signal-to-noise ratio. The results of this calibration yield source spectra and derived magnitudes that were more stable than any other direct-phase measure to date. Our empirical procedure accounted for all propagation, site, and S-to-coda transfer function effects. The resultant coda-derived moment-rate spectra were used to provide traditional band-limited magnitude (e.g., M{sub L}, m{sub b} etc.) as well as an unbiased, unsaturated magnitude (moment magnitude, M{sub w}) that is tied to a physical measure of earthquake size (i.e., seismic moment). We validated our results by comparing our coda-derived moment estimates with those obtained from long-period waveform modeling. We first tested and validated the method using events distributed along the Dead Sea Rift (e.g., Mayeda et al., 2003). Next, we tested the transportability of the method to earthquakes distributed across the entire country of Turkey and validated our results using seismic moments of over 50 events that had been previously waveform modeled using the method of Dreger and Helmberger, (1993). In both regions we demonstrated that the interstation magnitude scatter was significantly reduced when using the coda-based magnitudes (i.e., M{sub w}(coda) and m{sub b}(coda)). Once calibrated, the coda-derived source spectra provided stable, unbiased magnitude estimates for events that were too small either to be reliably waveform modeled or to be seen at far-regional and teleseismic distances. In general coda-derived magnitudes are roughly a factor of 3 to 5 more stable than traditional regional magnitudes that use the direct-phases such as P{sub g} and L{sub g}. This appears to be a universal observation for all regions where the coda methodology has been applied.

Mayeda, K; Eken, T; Hofstetter, A; Turkelli, N; O'Boyle, J; Orgulu, G; Gok, R

2003-07-17

367

Fluorescence emission spectra of calcofluor stained yeast cell suspensions: heuristic assessment of basis spectra for their linear unmixing.  

PubMed

Fluorescence emission spectra of yeast cell suspensions stained with calcofluor have recently been identified as promising markers of variations in the quality of yeast cell wall. It is shown in this paper how the raw fluorescence spectra of calcofluor can be transformed to reliable spectral signatures of cell wall quality, which are independent of actual dye-to-cell concentrations of examined cell suspensions. Moreover, the presented approach makes it possible to assess basis fluorescence spectra that allows for the spectral unmixing of raw fluorescence spectra in terms of respective fluorescence contributions of calcofluor solvated in the suspension medium and bound to yeast cell walls. PMID:22538834

Plášek, Jaromír; Dostál, Marek; Gášková, Dana

2012-07-01

368

HOT ELECTROMAGNETIC OUTFLOWS. I. ACCELERATION AND SPECTRA  

SciTech Connect

The theory of cold, relativistic, magnetohydrodynamic outflows is generalized by the inclusion of an intense radiation source. In some contexts, such as the breakout of a gamma-ray burst (GRB) jet from a star, the outflow is heated to a high temperature at a large optical depth. Eventually it becomes transparent and is pushed to a higher Lorentz factor by a combination of the Lorentz force and radiation pressure. We obtain its profile, both inside and outside the fast magnetosonic critical point, when the poloidal magnetic field is radial and monopolar. Most of the energy flux is carried by the radiation field and the toroidal magnetic field that is wound up close to the rapidly rotating engine. Although the entrained matter carries little energy, it couples the radiation field to the magnetic field. Then the fast critical point is pulled inward from infinity and, above a critical radiation intensity, the outflow is accelerated mainly by radiation pressure. We identify a distinct observational signature of this hybrid outflow: a hardening of the radiation spectrum above the peak of the seed photon distribution, driven by bulk Compton scattering. The non-thermal spectrum-obtained by a Monte Carlo method-is most extended when the Lorentz force dominates the acceleration, and the seed photon beam is wider than the Lorentz cone of the MHD fluid. This effect is a generic feature of hot, magnetized outflows interacting with slower relativistic material. It may explain why some GRB spectra appear to peak at photon energies above the original Amati et al. scaling. A companion paper addresses the case of jet breakout, where diverging magnetic flux surfaces yield strong MHD acceleration over a wider range of Lorentz factor.

Russo, Matthew [Department of Physics, University of Toronto, 60 St. George St., Toronto, ON M5S 1A7 (Canada); Thompson, Christopher [Canadian Institute for Theoretical Astrophysics, 60 St. George St., Toronto, ON M5S 3H8 (Canada)

2013-04-20

369

Hot Electromagnetic Outflows. I. Acceleration and Spectra  

NASA Astrophysics Data System (ADS)

The theory of cold, relativistic, magnetohydrodynamic outflows is generalized by the inclusion of an intense radiation source. In some contexts, such as the breakout of a gamma-ray burst (GRB) jet from a star, the outflow is heated to a high temperature at a large optical depth. Eventually it becomes transparent and is pushed to a higher Lorentz factor by a combination of the Lorentz force and radiation pressure. We obtain its profile, both inside and outside the fast magnetosonic critical point, when the poloidal magnetic field is radial and monopolar. Most of the energy flux is carried by the radiation field and the toroidal magnetic field that is wound up close to the rapidly rotating engine. Although the entrained matter carries little energy, it couples the radiation field to the magnetic field. Then the fast critical point is pulled inward from infinity and, above a critical radiation intensity, the outflow is accelerated mainly by radiation pressure. We identify a distinct observational signature of this hybrid outflow: a hardening of the radiation spectrum above the peak of the seed photon distribution, driven by bulk Compton scattering. The non-thermal spectrum—obtained by a Monte Carlo method—is most extended when the Lorentz force dominates the acceleration, and the seed photon beam is wider than the Lorentz cone of the MHD fluid. This effect is a generic feature of hot, magnetized outflows interacting with slower relativistic material. It may explain why some GRB spectra appear to peak at photon energies above the original Amati et al. scaling. A companion paper addresses the case of jet breakout, where diverging magnetic flux surfaces yield strong MHD acceleration over a wider range of Lorentz factor.

Russo, Matthew; Thompson, Christopher

2013-04-01

370

Dust Spectra from Above and Below  

NASA Technical Reports Server (NTRS)

Spectra of martian dust taken by the Mars Exploration Rover Spirit's mini-thermal emission spectrometer are compared to that of the orbital Mars Global Surveyor's thermal emission spectrometer. The graph shows that the two instruments are in excellent agreement.

Rover Senses Carbon Dioxide [figure removed for brevity, see original site] Click on image for larger view

This graph, consisting of data acquired on Mars from the Mars Exploration Rover Spirit's mini-thermal emission spectrometer, shows the light, or spectral, signature of carbon dioxide. Carbon dioxide makes up the bulk of the thin martian atmosphere.

Rover Senses Silicates [figure removed for brevity, see original site] Click on image for larger view

This graph, consisting of data acquired on Mars by the Mars Exploration Rover Spirit's mini-thermal emission spectrometer, shows the light, or spectral, signature of silicates - a group of minerals that form the majority of Earth's crust. Minerals called feldspars and zeolites are likely candidates responsible for this feature.

Rover Senses Bound Water [figure removed for brevity, see original site] Click on image for larger view

This graph, consisting of data acquired on Mars from the Mars Exploration Rover Spirit's mini-thermal emission spectrometer, shows the light, or spectral, signature of an as-of-yet unidentified mineral that contains bound water in its crystal structure. Minerals such as gypsum and zeolites are possible candidates.

Rover Senses Carbonates [figure removed for brevity, see original site] Click on image for larger view

This graph, consisting of data from the Mars Exploration Rover Spirit's mini-thermal emission spectrometer, shows the light, or spectral, signatures of carbonates - minerals common to Earth that form only in water. The detection of trace amounts of carbonates on Mars may be due to an interaction between the water vapor in the atmosphere and minerals on the surface.

2004-01-01

371

First Infrared Spectra of Nitrous Oxide Pentamer  

NASA Astrophysics Data System (ADS)

High resolution spectra have previously been studied for N_2O dimers (two isomers), trimers (one isomer), and tetramers (two isomers). Here, we assign two new bands to the N_2O pentamer. The bands are observed in the region of the N_2O ?b{1} fundamental using a tunable laser to probe a pulsed supersonic slit jet expansion. They are centered at 2233.9 and 2236.4 wn for 14N_2O, and at 2164.4 and 2166.8 wn for 15N_2O. Attribution to the pentamer is based on comparison of the observed rotational constants with theoretical ones from calculated cluster structures based on two rather different N_2O pair potentials. The first potential function is from a recent high level ab initio study. The second potential is a relatively simple empirical one, based partly on fitting to bulk properties. The likely pentamer structure is a completely unsymmetric one. It can be visualized starting with a highly symmetric oblate tetramer which is attacked by a fifth monomer, locating itself at a favorable distance and breaking the symmetry. Interestingly, analysis of the two bands yields very similar but not quite identical ground state parameters. We believe that they are due to distinct isomers having this same basic structure but differing in the orientation direction of one N_2O monomer. [1] R. Dawes, X.-G. Wang, A.W. Jasper, and T. Carrington, Jr., {J. Chem. Phys.} {133}, 134304 (2010). [2] B. Kutcha, R.D. Etters, and R. LeSar, {J. Chem. Phys.} {97}, 5662 (1992). [3] J.N. Oliaee, M. Dehghany, N. Moazzen-Ahmadi, and A.R.W. McKellar, {J. Chem. Phys.} {134}, 074310 (2011).

Rezaei, M.; Oliaee, J. Norooz; Moazzen-Ahmadi, N.; McKellar, A. R. W.

2012-06-01

372

Fast multidimensional NMR spectroscopy for sparse spectra.  

PubMed

Multidimensional NMR spectroscopy is widely used for studies of molecular and biomolecular structure. A major disadvantage of multidimensional NMR is the long acquisition time which, regardless of sensitivity considerations, may be needed to obtain the final multidimensional frequency domain coefficients. In this article, a method for under-sampling multidimensional NMR acquisition of sparse spectra is presented. The approach is presented in the case of two-dimensional NMR acquisitions. It relies on prior knowledge about the support in the two-dimensional frequency domain to recover an over-determined system from the under-determined system induced in the linear acquisition model when under-sampled acquisitions are performed. This over-determined system can then be solved with linear least squares. The prior knowledge is obtained efficiently at a low cost from the one-dimensional NMR acquisition, which is generally acquired as a first step in multidimensional NMR. If this one-dimensional acquisition is intrinsically sparse, it is possible to reconstruct the corresponding two-dimensional acquisition from far fewer observations than those imposed by the Nyquist criterion, and subsequently to reduce the acquisition time. Further improvements are obtained by optimizing the sampling procedure for the least-squares reconstruction using the sequential backward selection algorithm. Theoretical and experimental results are given in the case of a traditional acquisition scheme, which demonstrate reliable and fast reconstructions with acceleration factors in the range 3-6. The proposed method outperforms the CS methods (OMP, L1) in terms of the reconstruction performance, implementation and computation time. The approach can be easily extended to higher dimensions and spectroscopic imaging. PMID:24664959

Merhej, Dany; Ratiney, Hélène; Diab, Chaouki; Khalil, Mohamad; Sdika, Michaël; Prost, Rémy

2014-06-01

373

Noise level and ultrasound spectra during burring.  

PubMed

The aim of this study was to evaluate the noise spectra of current dentistry equipment during normal work at the dental clinic and in the laboratory. In the study, noise was measured during the dental treatment of seven patients at a dental clinic and also in the acoustics laboratory, where working noise was simulated by drilling a polyacetal plate. All samples were analyzed in audible and ultrasonic areas in the one-third octave bands of 20-80,000 Hz. The measuring instruments used were B&K 4135 microphones, B&K 2633 preamplifiers, the B&K 2811 multiplexer, and the B&K 2133 real-time analyzer with the ZT 0318 high-frequency expansion unit. In the in situ measurements, the A-weighted sound pressure level was occasionally over 85 dB(A), and the equivalent continuous A-weighted sound pressure level, L(Aeq), was 76 dB(A). The noise level was most powerful in the one-third octave band of 40,000 Hz, where it was 74 dB. In laboratory measurements, the noise levels of the air-turbine and the micromotor hand pieces (n=16) were also most powerful in the one-third octave band of 40,000 Hz, where they were 80-89 dB. The L(Aeq) of the different micromotor handpieces (n=6) varied between 76 dB(A) and 77 dB(A), and the L(Aeq) of the turbine hand pieces (n=10) varied between 77 dB(A) and 82 dB(A). The noise of the drills is most powerful in the high frequencies, so using hearing protectors, it is possible that speech communication improves because the protectors attenuate high frequencies more than low frequencies. The very light protectors give sufficient protection against the drilling noise. PMID:12271344

Sorainen, E; Rytkönen, E

2002-09-01

374

Fitting of combined Ulysses/COMPTEL GRB spectra  

E-print Network

Fitting of combined Ulysses/COMPTEL GRB spectra J. Greiner 1 , T. Aigner 1 , M. Sommer 1 , O, 31029 Toulouse, France We have analysed the Ulysses and COMPTEL spectral data from several strong obtained by a joint deconvolution of the Ulysses and COMPTEL spectra (ranging from 20 keV up to 10 Me

Greiner, Jochen

375

X-ray Emission Spectra from Comets and Planets  

NASA Astrophysics Data System (ADS)

A description is presented of the spectrum that arises from the capture of electrons from neutral molecules by energetic multicharged positive ions. It is contrasted with that anticipated from fast electron impact. The origins of features observed in cometary and planetary spectra are discussed. The utility of the spectra as a measure of solar wind composition is demonstrated.

Dalgarno, A.

2001-05-01

376

The unusual outburst spectra of the cataclysmic variable IP Peg  

Microsoft Academic Search

Spectra are presented for the cataclysmic varible IP Peg for the period while the system was reaching the peak of an outburst. The average characteristics of the spectra are discussed and the orbital parameters are solved using the emission line profiles. The line profile evolution during and outside of the eclipse is examined and changes in the intensity of the

Francois Piche; Paula Szkody

1989-01-01

377

Symmetry breaking and spectra of diphenyloctatetraene in n-alkanes  

NASA Astrophysics Data System (ADS)

One- and two-photon excitation spectra, as well as absorption and emission spectra of diphenyloctatetraene (DPOT) in n-alkanes are investigated at low temperatures. For DPOT in n-octane we report on the measurements of one-photon excitation and emission spectra and for DPOT in n-tetradecane (TD) on the measurements of one- and two-photon excitation spectra and emission spectra. The spectra are governed by the transitions between the electronic ground (S0) and the two lowest electronic excited singlet states (S1,S2). The interpretation is based on allowed transitions and transitions induced by the S1-S2 coupling due to Herzberg-Teller promoting modes or due to static lattice-induced distortions of DPOT. A single noncentrosymmetric site is observed for DPOT in n-octane. For DPOT in TD a centrosymmetric and a noncentrosymmetric site are reported. The analysis indicates that there is a dynamical equilibrium in the population of these two sites. The experimental data are quantitatively studied by comparison with simulated spectra. The simulation calculations are based on the coupling between nonadiabatic S1 and S2 states, harmonic modes, and suitable transition moments and line-shape functions. For DPOT in TD the calculations reveal an interesting interference pattern in the vibronic progressions observed in two-photon excitation spectra.

Walser, Daniel; Zumofen, Gert; Plakhotnik, Taras

2000-11-01

378

[Significance of fluorescence spectra for the evaluation of lens opacities].  

PubMed

The fluorescence spectra of nucleus and cortex material from human lenses obtained as a result of extracapsular cataract extraction were observed. With advancing cataract formation the fluorescence spectra changed in a very characteristic way. The changes in ascorbic acid were compared with those caused by cataract development. Clinical application of corresponding measuring instruments would appear to make sense. PMID:3761991

Strobel, J; Jacobi, K W; Lohmann, W; Schmehl, W; Wunderling, M; Ibrahim, M

1986-08-01

379

Spectra of heavy-light mesons at finite temperature  

E-print Network

Spectra of heavy-light meson are studied using potential model and thermofield dynamics prescription. The mass spectra of different heavy-light mesons are calculated at different temperatures and compared with those at T=0. It is found that the binding mass of heavy-light meson decreases as temperature increases.

D. U. Matrasulov; Kh. T. Butanov; Kh. Yu. Rakhimov; F. C. Khanna

2009-09-13

380

Measurements of fast-neutron spectra in reactor shields  

Microsoft Academic Search

Experimental techniques previously used for measuring neutron spectra ; in fast critical assemblies have been applied to reactor shielding problems. ; Fast-neutron spectra in the energy range from 25 MeV to 1 MeV have been measured ; in the water shield surrounding a small thermal research reactor. Three ; different water thicknesses were investigated, as well as a combination of

C. D. Livengood; C. K. Paulson; H. E. Hungerford

1973-01-01

381

Doppler Spectra and Estimated Windspeed of a Violent Tornado  

Microsoft Academic Search

Presented in this Paper are Doppler spectra of a very large tornado that occurred on 22 May 1981 near Binger, Oklahoma. Tracking of the tornado was accomplished with the help of a novel `polar spectra display.' Bimodal tornado spectral signatures (TSS) were observed in about 40 scans. Direct measurements of maximum velocities from spectral skirts yielded a maximum tangential speed

Dusan Zrni; Donald W. Burgess; Larry Hennington

1985-01-01

382

Vibrational spectra of the two hydrates of strontium oxalate  

NASA Astrophysics Data System (ADS)

The infrared and Raman spectra of the two hydrates of strontium oxalate, SrC2O4?H2O and SrC2O4?2H2O, were recorded and discussed on the basis of their structural peculiarities and in comparison with the spectra of the related calcium oxalates and other previously investigated metallic oxalates.

D'Antonio, Maria C.; Torres, María M.; Palacios, Daniel; González-Baró, Ana C.; Baran, Enrique J.

2015-02-01

383

Periodic Orbit Expansions for Power Spectra of Chaotic Systems  

E-print Network

Dynamik, Universit¨at Potsdam, Neuen Palais (Physik), D-O- 1571 Potsdam, Germany 3 PC: file articles mappings. 1 INTRODUCTION We apply the transfer operator techniques to the evaluation of power spectra components of power spectra of maps whose dynamics is chaotic. 4 2 TRANSFER OPERATORS We seek to compute

Cvitanovc', Predrag

384

Vibrational spectra of the two hydrates of strontium oxalate.  

PubMed

The infrared and Raman spectra of the two hydrates of strontium oxalate, SrC2O4?H2O and SrC2O4?2H2O, were recorded and discussed on the basis of their structural peculiarities and in comparison with the spectra of the related calcium oxalates and other previously investigated metallic oxalates. PMID:25238188

D'Antonio, Maria C; Torres, María M; Palacios, Daniel; González-Baró, Ana C; Baran, Enrique J

2015-02-25

385

REALISTIC SIMULATION OF OCEAN SURFACE USING WAVE SPECTRA  

E-print Network

REALISTIC SIMULATION OF OCEAN SURFACE USING WAVE SPECTRA Jocelyn Fr´echot LaBRI - Laboratoire CEDEX, France jocelyn.frechot@labri.fr Keywords: Natural phenomena, realistic ocean waves, procedural wave spectra are independent of the ocean model, Gerstner parametric equations and Fourier transform

Paris-Sud XI, Université de

386

Explanation of the surface peak in charge integrated LEIS spectra  

Microsoft Academic Search

Low energy ion scattering is very surface sensitive if scattered ions are analyzed. By time-of-flight (TOF) techniques, also neutral and charge integrated spectra (ions plus neutrals) can be obtained, which yield information about deeper layers. In the literature, the observation of a more or less pronounced surface peak was reported for charge integrated spectra, the intensity of the surface peak

M. Draxler; R. Beikler; E. Taglauer; K. Schmid; R. Gruber; S. N Ermolov; P. Bauer

2003-01-01

387

Tuesday, March 13, 2007 ASTEROID OBSERVATIONS: SPECTRA, MOSTLY  

E-print Network

-class asteroids. We report results of follow-up spectroscopy to confirm/refute V- and Q-type main-belt asteroid. Comparisons to spectra of petrographically controlled CAIs, the oldest materials in the solar system history of the solar system. We present a progress report of our reflectance spectra studies of twenty

Rathbun, Julie A.

388

Web Spectra: Problems in NMR and IR spectroscopy  

NSDL National Science Digital Library

This site was established to provide chemistry students with a library of spectroscopy problems. Interpretation of spectra is a technique that requires practice - this site provides 1H NMR and 13 C NMR, DEPT, COSY and IR spectra of various compounds for students to interpret. Hopefully, these problems will provide a useful resource to better understand spectroscopy.

Merlic, Craig A.

389

Modal Spectra Seismic Analysis for non-uniform excitation  

SciTech Connect

The Independent Support Motion (ISM) method of Modal Spectra Seismic Analysis (MSSA) applies to structural systems subject to non-uniform excitation. This paper presents the merits of the ISM method over the Envelope Response Spectra (ERS) method of MSSA, discusses adequacy of the supports group definition, evaluates the effect of support motions correlation, and explains the response patterns and dependency on problem characteristics.

Vashi, K.M.

1990-01-01

390

Modal Spectra Seismic Analysis for non-uniform excitation  

SciTech Connect

The Independent Support Motion (ISM) method of Modal Spectra Seismic Analysis (MSSA) applies to structural systems subject to non-uniform excitation. This paper presents the merits of the ISM method over the Envelope Response Spectra (ERS) method of MSSA, discusses adequacy of the supports group definition, evaluates the effect of support motions correlation, and explains the response patterns and dependency on problem characteristics.

Vashi, K.M.

1990-12-31

391

"Perfecting" WATERGATE: clean proton NMR spectra from aqueous solution.  

PubMed

A simple modification of the WATERGATE solvent suppression method greatly improves the quality of (1)H NMR spectra obtainable from samples in H(2)O. The new method allows (1)H signals to be measured even when close in chemical shift to the signal of water, as for example in the NMR spectra of carbohydrates. PMID:23192194

Adams, Ralph W; Holroyd, Chloe M; Aguilar, Juan A; Nilsson, Mathias; Morris, Gareth A

2013-01-14

392

Raman spectra of dipicolinic acid in crystalline and liquid environments  

Microsoft Academic Search

Raman spectra of dipicolinic acid (DPA) are important for detection of bacterial spores, since DPA and its salts present one of their major components. The implementation of a deeply cooled CCD camera in combination with pulsed excitation at 532nm allowed measuring well-resolved Raman spectra of the DPA in different forms. Powder preparations, crystals grown from saturated solutions and aqueous solutions

A. A. Kolomenskii; H. A. Schuessler

2005-01-01

393

WebSpectra: Problems in NMR and IR Spectroscopy  

NSDL National Science Digital Library

This site was established to provide chemistry students with a library of spectroscopy problems. 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.

394

Detection of nonconductive heat transport in soils using spectra analysis  

Microsoft Academic Search

Variance spectra were generated for three high-frequency near-surface soil temperature time series representative of soil conditions typically encountered in temperate regions: saturation, strong evaporation, and soil frost penetration. For the latter two conditions, a surrogate measure of the soil water ionic concentration was also obtained and variance spectra were calculated. In a purely conductive system of multiday duration, maximum thermal

Kenneth M. Hinkel; Samuel I. Outcalt

1993-01-01

395

Self adjoint operators and their spectra V.S. Sunder  

E-print Network

Self adjoint operators and their spectra V.S. Sunder Institute of Mathematical Sciences Chennai, India sunder@imsc.res.in IIT(Madras), April 21st, 2011 V.S. Sunder IMSc, Chennai Self adjoint operators and their spectra #12;Cyclic vectors and tridiagonality Our interest will be in self-adjoint operators A on Hilbert

Sunder, V S

396

Spent-fuel photon and neutron source spectra  

SciTech Connect

Computational activities at Oak Ridge National Laboratory have been performed to develop appropriate data and techniques for computing the photon and neutron source spectra of spent fuel. The methods reviewed here include both the determination of spent-fuel composition and the radiation source spectra associated with these isotopic inventories.

Hermann, O.W.; Alexander, C.W.

1983-01-01

397

Recovery of constituent spectra using non-negative matrix factorization  

E-print Network

Separation, Raman Spectroscopy, Hy- perspectral Imaging (HSI), Chemical Shift Imaging (CSI), Nuclear Magnetic to generate the spectra. Raman Spectroscopy: Raman spectra, which are based on the vibrational motions. Results for Raman spectral data, hyperspectral images, and 31 P human brain data are provided

Parra, Lucas C.

398

ARES I-X USS Fracture Analysis Loads Spectra Development  

NASA Technical Reports Server (NTRS)

This report describes the development of a set of bounding load spectra for the ARES I-X launch vehicle. These load spectra are used in the determination of the critical initial flaw size (CIFS) of the welds in the ARES I-X upper stage simulator (USS).

Larsen, Curtis; Mackey, Alden

2008-01-01

399

hal00276997, Raman spectra of misoriented bilayer graphene  

E-print Network

hal­00276997, version 1 ­ 5 May 2008 Raman spectra of misoriented bilayer graphene P. Poncharal 1 spectra from single layer graphene with a bilayer in which the two layers are arbitrarily misoriented to the similarity of the electronic structures of single layer graphene and misoriented bilayer graphene. Another

Paris-Sud XI, Université de

400

Mineral abundance determination: Quantitative deconvolution of thermal emission spectra  

Microsoft Academic Search

A linear retrieval (spectral deconvolution) algorithm is developed and applied to high-resolution laboratory infrared spectra of particulate mixtures and their end- members. The purpose is to place constraints on, and test the viability of, linear spectral deconvolution of high-resolution emission spectra. The effects of addition of noise, data reproducibility, particle size variation, an increasing number of minerals in the mixtures,

Michael S. Ramsey; Philip R. Christensen

1998-01-01

401

Infrared spectra of evolved stars with unusual dust shells  

NASA Astrophysics Data System (ADS)

New mid-infrared spectra are presented of a number of oxygen-rich evolved stars which have IRAS LRS (Low Resolution Spectrometer) spectra that were classified as showing SiC emission. Two of the sources, IRC-20445 and IRC-20461, show the unidentified infrared (UIR) bands superposed on silicate emission features. Both objects have been classified as M supergiants. Several other sources show three-component spectra, with peaks at 10, 11 and 13?m. The 13-?m source FI Lyr shows a narrow emission feature at 19?m. Emission by oxide grains may be responsible for the 11-, 13- and 19-?m features. One object, IRC-20455, shows a self-absorbed silicate feature. There is no clear evidence for SiC emission in any of the spectra: the LRS spectra were erroneously classified as showing SiC emission because of the relatively strong 11-?m emission.

Sylvester, R. J.

1999-10-01

402

Pluto and Charon's UV spectra from IUE to New Horizons  

NASA Astrophysics Data System (ADS)

We compare Mid-Ultraviolet (MUV) spectra of Pluto taken over a period of 20 years by the International Ultraviolet Explorer, the HST-Faint Object Spectrograph, and the HST-Cosmic Origins Spectrograph. We extract Pluto-only spectra from the IUE data and associate them with corrected longitudes when necessary. Comparing them with HST spectra provides further evidence of temporal changes in Pluto's geometric albedo between 2000 and 3200 Å. These various spectra are used to explore the contributions of atmospheric or surface changes to Pluto's reflectance. We also provide predictions for the Far-Ultraviolet (FUV) surface reflectance and atmospheric emission spectra of Pluto that will be measured by the Alice spectrograph (Stern, S.A. et al. [2008]. Space Sci. Rev. 140, 155-187) during the New Horizons flyby of Pluto in 2015. FUV surface reflectance predictions are also made for Charon, Hydra, and Nix.

Schindhelm, Eric; Stern, S. Alan; Gladstone, Randy; Zangari, Amanda

2015-01-01

403

Constraining Galaxy Evolution Using Observed UV-Optical Spectra  

NASA Technical Reports Server (NTRS)

Our understanding of galaxy evolution depends on model spectra of stellar populations, and the models are only as good as the observed spectra and stellar parameters that go into them. We are therefore evaluating modem UV-optical model spectra using Hubble's Next Generation Spectral Library (NGSL) as the reference standard. The NGSL comprises intermediate-resolution (R is approximately 1000) STIS spectra of 378 stars having a wide range in metallicity and age. Unique features of the NGSL include its broad wavelength coverage (1,800-10,100 A) and high-S/N, absolute spectrophotometry. We will report on a systematic comparison of model and observed UV-blue spectra, describe where on the HR diagram significant differences occur, and comment on current approaches to correct the models for these differences.

Heap, Sally

2007-01-01

404

The first observation of Carbon-13 spin noise spectra  

PubMed Central

We demonstrate the first 13C NMR spin noise spectra obtained without any pulse excitation by direct detection of the randomly fluctuating noise from samples in a cryogenically cooled probe. Noise power spectra were obtained from 13C enriched methanol and glycerol samples at 176 MHz without and with 1H decoupling, which increases the sensitivity without introducing radio frequency interference with the weak spin noise. The multiplet amplitude ratios in 1H coupled spectra indicate that, although pure spin noise prevails in these spectra, the influence of absorbed circuit noise is still significant at the high concentrations used. In accordance with the theory heteronuclear Overhauser enhancements are absent from the 1H-decoupled 13C spin noise spectra. PMID:23041799

Schlagnitweit, Judith; Müller, Norbert

2012-01-01

405

Impedance spectra of hot, dry silicate minerals and rocks: qualitative interpretation of spectra  

USGS Publications Warehouse

Impedance spectroscopy helps distinguish the contributions that grain interiors and grain boundaries make to electrical resistance of silicate minerals and rocks. Olivine, orthopyroxene, clinopyroxenes, and both natural and synthetic clinopyroxenite were measured. A network of electrical elements is presented for use in interpreting impedance spectra and conductive paths in hot or cold, wet or dry, minerals and rocks at any pressure. In dry rocks, a series network path predominates; in wet rocks, aqueous pore fluid and crystals both conduct. Finite resistance across the sample-electrode interface is evidence that electronic charge carriers are present at the surface, and presumably within, the silicate minerals and rocks measured. -from Authors

Huebner, J.S.; Dillenburg, R.G.

1995-01-01

406

Molecular Interactions between the Specialist Herbivore Manduca sexta (Lepidoptera, Sphigidae) and Its Natural Host Nicotiana attenuata. VIII. An Unbiased GCxGC-ToFMS Analysis of the Plant's Elicited Volatile Emissions[W][OA  

PubMed Central

Treating wounds in Nicotiana attenuata leaves with Manduca sexta oral secretions (W+OS) mimics most changes elicited by M. sexta herbivory, but an unbiased analysis of the effect of the different OS constituents on volatile emissions is lacking. We used two-dimensional gas chromatography/time-of-flight (GCxGC-ToF) mass spectrometry combined with multivariate statistics to parse volatiles into regulatory patterns. Volatiles released by wounding alone and by the alkalinity of OS were assessed by applying a buffer known to mimic the pH-mediated changes of OS elicitation (pectin methyl esterase activation and methanol release). The activities of fatty acid amino acid conjugates, well-known elicitors of antiherbivore defenses, and of 2-hydroxyoctadecatrienoic acid, a newly discovered signal in OS, were determined. Approximately 400 analytes were detected after deconvolution and alignment of GCxGC data; 35 volatiles were significantly regulated upon W+OS. Two-thirds of these were specifically regulated by OS, being either amplified (most terpenoids and certain hexenylesters) or strongly repressed (many short-chain alcohols and some aromatic and hexenylester derivatives). Fatty acid amino acid conjugates played a central role in this pattern of regulation, since they induced the emission of half of OS-elicited volatiles and inhibited the production of almost all OS-repressed volatiles; 2-hydroxyoctadecatrienoic acid influenced emission of trans-?-bergamotene, while other unknown OS constituents amplified hexenylester production. We conclude that the complex bouquet of herbivory-elicited volatiles results from the complex modulations of the wound response by diverse cues found in OS. This work also underscores the value of ultra-high-resolution GCxGC-ToF analysis combined with the nontargeted mining of the resulting data. PMID:19136568

Gaquerel, Emmanuel; Weinhold, Alexander; Baldwin, Ian T.

2009-01-01

407

EFFECTS OF FORSTERITE GRAIN SHAPE ON INFRARED SPECTRA  

SciTech Connect

The Infrared Space Observatory (ISO) detected several sharp infrared features around young stars, comets, and evolved stars. These sharp features were identified as Mg-rich crystalline silicates of forsterite and enstatite by comparison with spectra from laboratory data. However, certain infrared emission bands in the observed spectra cannot be identified because they appear at slightly shorter wavelengths than the peaks in forsterite laboratory spectra, where the shapes of forsterite particles are irregular. To solve this problem, we measured infrared spectra of forsterite grains of various shapes (irregular, plate-like with no sharp edges, elliptical, cauliflower, and spherical) in the infrared spectral region between 5 and 100 mum. The spectra depend on particle shape. The spectra of the 11, 19, 23, and 33 mum bands, in particular, are extremely sensitive to particle shape, whereas some peaks such as the 11.9, 49, and 69 mum bands remained almost unchanged despite different particle shapes. This becomes most evident from the spectra of near-spherical particles produced by annealing an originally amorphous silicate sample at temperature from 600 to 1150 deg. C. The spectra of these samples differ strongly from those of other ones, showing peaks at much shorter wavelengths. At a higher annealing temperature of 1200 deg. C, the particle shapes changed drastically from spherical to irregular and the spectra became similar to those of forsterite particles with irregular shapes. Based on ISO data and other observational data, the spectra of outflow sources and disk sources may correspond to differences in forsterite shape, and further some unidentified peaks, such as those at 32.8 or 32.5 mum, may be due to spherical or spherical-like forsterite.

Koike, C.; Imai, Y.; Chihara, H.; Murata, K.; Tsuchiyama, A. [Department of Earth and Space Science, Osaka University, Toyonaka 560-0043 (Japan); Suto, H. [Subaru Telescope, National Astronomical Observatory of Japan, Hilo, HI (United States); Tachibana, S. [Department of Earth and Planetary Science, University of Tokyo, Tokyo 113-0033 (Japan); Ohara, S., E-mail: koike@astroboy.ess.sci.osaka-u.ac.j [Joining and Welding Research Institute, Osaka University, Ibaraki 567-0047 (Japan)

2010-02-01

408

Effects of Forsterite Grain Shape on Infrared Spectra  

NASA Astrophysics Data System (ADS)

The Infrared Space Observatory (ISO) detected several sharp infrared features around young stars, comets, and evolved stars. These sharp features were identified as Mg-rich crystalline silicates of forsterite and enstatite by comparison with spectra from laboratory data. However, certain infrared emission bands in the observed spectra cannot be identified because they appear at slightly shorter wavelengths than the peaks in forsterite laboratory spectra, where the shapes of forsterite particles are irregular. To solve this problem, we measured infrared spectra of forsterite grains of various shapes (irregular, plate-like with no sharp edges, elliptical, cauliflower, and spherical) in the infrared spectral region between 5 and 100 ?m. The spectra depend on particle shape. The spectra of the 11, 19, 23, and 33 ?m bands, in particular, are extremely sensitive to particle shape, whereas some peaks such as the 11.9, 49, and 69 ?m bands remained almost unchanged despite different particle shapes. This becomes most evident from the spectra of near-spherical particles produced by annealing an originally amorphous silicate sample at temperature from 600 to 1150°C. The spectra of these samples differ strongly from those of other ones, showing peaks at much shorter wavelengths. At a higher annealing temperature of 1200°C, the particle shapes changed drastically from spherical to irregular and the spectra became similar to those of forsterite particles with irregular shapes. Based on ISO data and other observational data, the spectra of outflow sources and disk sources may correspond to differences in forsterite shape, and further some unidentified peaks, such as those at 32.8 or 32.5 ?m, may be due to spherical or spherical-like forsterite.

Koike, C.; Imai, Y.; Chihara, H.; Suto, H.; Murata, K.; Tsuchiyama, A.; Tachibana, S.; Ohara, S.

2010-02-01

409

An Application of New Experimentally Received FTIR-Spectra to the Analysis and Comparison with Martian Spectra  

NASA Astrophysics Data System (ADS)

Using non-KBr method it was possible to recorder spectra of different powdered mineral substances, materials and gas components simultaneously, water solution and suspensions. The new method can be applied practically to simulate IR-spectra of components of martian surface and dust composition.

Maxe, L. P.

2006-03-01

410

Optical spectra of Vb(3+) in crystals with scheelite structure. 1: Explanation of the spectra  

NASA Astrophysics Data System (ADS)

The optical and Zeeman spectra are reported for Yb(3&) in nine single crystals of the Scheelite family at temperatures varying between 1.9 and 300 K and impurity ion concentration varying between 0.05 and 4 percent. The scheelite crystals examined were CaWO4, CaMoO4, SrWO4, SrMoO4, PbWO4, PbMoO4, Cd-MoO4, BaWO4, and LiYF4. The Yb(3&) ion substitutes for the cation and experiences a crystalline electric field of S4 point symmetry. The spectra were found to be highly structured containing the S4 electronic transitions, concentration dependent lines originating from low symmetry sites caused by lattice defects, and features tentatively identified as vibronic transitions. Vibronic selection rules for Yb(3&) in scheelite, which belongs to the C(6)4h space group, have been calculated. Identification of the S4 spectral lines allowed the energy level schemes for Yb(3&) in the nine scheelites to be determined.

Brown, E. A.

1980-09-01

411

An example of scaling MST Doppler spectra using median spectra, spectral smoothing, and velocity tracing  

NASA Technical Reports Server (NTRS)

Although automatic, computer scaling methods appeared at the start of the MST (mesosphere stratosphere troposphere) radar technique, there is a continuing need for scaling algorithms that perform editing functions and increase the sensitivity of radar by post processing. The scaling method presented is an adaptation of the method of scaling MST Doppler spectra presented by Rastogi (1984). A brief overview of this method is as follows: a median spectrum is calculated from several sequential spectra; the median noise value is subtracted from this derived spectrum; the median spectrum is smoothed; the detection/nondetection decision is made by comparing the smoothed spectrum to the variance of the smoothed noise; and if a signal is detected, then the half-power points of the smoothed echo spectrum are used to place limits on the evaluation of the first two moments of the unsmoothed median spectrum. In all of the above steps, the algorithm is guided by tracing the expected velocity range upward from the lowest range as far as possible. The method is discussed in more detail.

Green, J. L.

1986-01-01

412

Rapid unbiased bipolar incoherent calculator cube  

SciTech Connect

An electrooptical engagement array architecture for performing matrix-matrix multiplication using incoherent light is presented. Key components of this newly proposed processing device include a single pulsed incoherent light source, two dynamic light valves, and a two-dimensional photodetector array. 20 references.

Bocker, R.P.; Caulfield, H.F.; Bromley, K.

1983-01-01

413

Unbiased rigid registration using transfer functions  

NASA Astrophysics Data System (ADS)

The evaluation of tumor growth as regression under therapy is an important clinical issue. Rigid registration of sequentially acquired 3D-images has proven its value for this purpose. Existing approaches to rigid image registration use the whole volume for the estimation of the rigid transform. Non-rigid soft tissue deformation, however, will imply a bias to the registration result, because local deformations cannot be modeled by rigid transforms. Anatomical substructures, like bones or teeth, are not affected by these deformations, but follow a rigid transform. This important observation is incorporated in the proposed registration algorithm. The selection of anatomical substructure is done by manual interaction of medical experts adjusting the transfer function of the volume rendering software. The parameters of the transfer function are used to identify the voxels that are considered for registration. A rigid transform is estimated by a quaternion gradient descent algorithm based on the intensity values of the specified tissue classes. Commonly used voxel intensity measures are adjusted to the modified registration algorithm. The contribution describes the mathematical framework of the proposed registration method and its implementation in a commercial software package. The experimental evaluation includes the discussion of different similarity measures, the comparison of the proposed method to established rigid registration techniques and the evaluation of the efficiency of the new method. We conclude with the discussion of potential medical applications of the proposed registration algorithm.

Hahn, Dieter A.; Hornegger, Joachim; Bautz, Werner; Kuwert, Torsten; Roemer, Wolfgang

2005-04-01

414

Unbiased Estimation 14.1 Introduction  

E-print Network

this by looking a the computation of the mean and the variance of 16 flips of a fair coin. Give this task to 10(x)/10 [1] 7.8 The result is a bit below 8. Is this systematic? To assess this, we appeal to the ideas with a computation to verify our guess. For 16 tosses of a fair coin, we know that the variance is np(1 p) = 16 · 1

Watkins, Joseph C.

415

On unbiased backtransform of lognormal kriging estimates  

Microsoft Academic Search

Lognormal kriging is an estimation technique that was devised for handling highly skewed data distributions. This technique\\u000a takes advantage of a logarithmic transformation that reduces the data variance. However, backtransformed lognormal kriging\\u000a estimates are biased because the nonbias term is totally dependent on a semivariogram model. This paper proposes a new approach\\u000a for backtransforming lognormal kriging estimates that not only

Jorge Kazuo Yamamoto

2007-01-01

416

NIR Spectra of Type Ia Supernovae: High-Cadence Observations  

NASA Astrophysics Data System (ADS)

New observing resources and coordinated scheduling make it possible to obtain sequences of NIR spectra from individual supernovae on a regular basis. In the past three years the Carnegie Supernova Project II and the CfA Supernova Group have obtained 350 NIR spectra of 78 supernovae. Here we describe eight series of NIR spectra from Type Ia supernovae for which there are ten or more observations with 4 or more of the spectra obtained before Mg II becomes undetectable at about six days post-maximum. NIR spectra are particularly useful for tracing the burning history of the outer layers in SN Ia and the presence of Mg II defines the limit of the carbon burning region. Recent analysis suggests that all significant absorption features in spectra of SN Ia are blends of two or more lines. Data sets with higher spectral cadence are more successful at breaking line-identification degeneracies and consequently provide more accurate information about line profiles and velocity measurements. Three of the eight spectral series in this sample include more than 20 observations and in two cases, there are 12 spectra between -12d and +6d with respect to B-max. The eight SN Ia vary from -18.0 to -19.5 in absolute magnitude and we explore the differences between the supernovae in the timing and strength of spectral features. We make qualitative comparisons of these results to theoretical models for the chemical distribution of materials in SN Ia.

Marion, Howie H.; Hsiao, E.; Vinko, J.; Parrent, J. T.; Silverman, J. M.; Kirshner, R. P.; Phillips, M.; Wheeler, J. C.; Burns, C. R.; Morrell, N.; Contreras, C.; Challis, P.; Supernova Project, Carnegie, II; CfA Supernova Group

2014-01-01

417

THE Be STAR SPECTRA (BeSS) DATABASE  

SciTech Connect

Be stars vary on many timescales, from hours to decades. A long time base of observations to analyze certain phenomena in these stars is therefore necessary. Collecting all existing and future Be star spectra into one database has thus emerged as an important tool for the Be star community. Moreover, for statistical studies, it is useful to have centralized information on all known Be stars via an up-to-date catalog. These two goals are what the Be Star Spectra (BeSS, http://basebe.obspm.fr) database proposes to achieve. The database contains an as-complete-as-possible catalog of known Be stars with stellar parameters, as well as spectra of Be stars from all origins (any wavelength, any epoch, any resolution, etc.). It currently contains over 54,000 spectra of more than 600 different Be stars among the {approx}2000 Be stars in the catalog. A user can access and query this database to retrieve information on Be stars or spectra. Registered members can also upload spectra to enrich the database. Spectra obtained by professional as well as amateur astronomers are individually validated in terms of format and science before being included in BeSS. In this paper, we present the database itself as well as examples of the use of BeSS data in terms of statistics and the study of individual stars.

Neiner, C.; De Batz, B. [LESIA, UMR 8109 du CNRS, Observatoire de Paris, UPMC, Univ. Paris Diderot, 92195 Meudon Cedex (France); Cochard, F. [Shelyak Instruments, Les Roussets, 38420 Revel (France); Floquet, M.; Mekkas, A. [GEPI, UMR 8111 du CNRS, Observatoire de Paris, Univ. Paris Diderot, 92195 Meudon Cedex (France); Desnoux, V., E-mail: coralie.neiner@obspm.fr [ARAS, Astronomical Ring for Access to Spectroscopy (Country Unknown)

2011-11-15

418

Obtaining absolute acoustic spectra in an aerodynamic wind tunnel  

NASA Astrophysics Data System (ADS)

Cost effective methods for identifying and reducing sources of noise have become essential in the design of many modern transport vehicles. Whilst closed-section wind tunnels can readily evaluate aerodynamic performance, obtaining accurate acoustic spectra is often a major challenge because of the poor signal to noise ratios available. In this paper, methods of obtaining absolute spectra from the non-acoustically treated Markham wind tunnel at the University of Cambridge are discussed. Initial measurements with a small monopole source compare well with simulations and show that it is possible to obtain similar spectra from two nested acoustic arrays. However, a series of further experiments with simplified landing gear models show very different spectra from each array. By comparing measurements with simulations, it is shown that negative side lobes affect beamforming source maps. Measurements of an 'empty tunnel' cross spectral matrix allow the removal of sidelobes, providing much greater consistency between spectra. Finally, a dipole beamforming vector is used to account for the directivity of the landing gear noise, leading to good agreement between absolute spectra from the differently sized arrays. This analysis demonstrates that data from a phased array in a hard-walled, aerodynamic wind tunnel can provide meaningful acoustic spectra from low-noise models.

Quayle, Alexander R.; Dowling, Ann P.; Graham, W. R.; Babinsky, H.

2011-05-01

419

Funny hills in pion spectra from heavy-ion collisions  

SciTech Connect

A discussion of some of the systematic features of the pion spectra in heavy-ions reactions is given. A discussion of the hills and valleys in heavy ion pion spectra that show up at the lower pion energies is given. The following topics are discussed: (1) three kinds of funny hills; (2) ..pi../sup -///sup +/ ratios near center of mass; (3) new Monte Carlo studies of charged pion spectra; and (4) pion orbiting about fireballs and Bose-Einstein behavior as explanation for the mid-rapidity P/sub perpendicular to/ approx. = 0.4 to 0.5 m/sub ..pi../c hill. (WHK)

Rasmussen, J.O.

1982-03-01

420

Spectra of random graphs with arbitrary expected degrees  

NASA Astrophysics Data System (ADS)

We study random graphs with arbitrary distributions of expected degree and derive expressions for the spectra of their adjacency and modularity matrices. We give a complete prescription for calculating the spectra that is exact in the limit of large network size and large vertex degrees. We also study the effect on the spectra of hubs in the network, vertices of unusually high degree, and show that these produce isolated eigenvalues outside the main spectral band, akin to impurity states in condensed matter systems, with accompanying eigenvectors that are strongly localized around the hubs. We give numerical results that confirm our analytic expressions.

Nadakuditi, Raj Rao; Newman, M. E. J.

2013-01-01

421

Photoacoustic spectra of MoS/sub 2/  

SciTech Connect

The photoacoustic spectra of powdered MoS/sub 2/ prepared by particle-size reduction and dilution have been determined and compared with the optical transmittance spectra of single crystals and thin-film deposits. MoS/sub 2/ was chosen as a typical representative of the layer-structured transition metal dichalcogenides, for which optical properties are important in explaining their unusual structural and transport properties. Reasonably well-resolved photoacoustic spectra were obtained by a layering technique using KCl as a diluent. Analysis of the experiments indicated that the spectral resolution was obtained not by reduction in photoacoustic signal saturation but by the enhancement of diffuse reflectance.

Carlson, K.D.; Hodul, D.

1983-09-15

422

Comparison of the cathodo- and ?-luminescence spectra of scintillation crystals  

NASA Astrophysics Data System (ADS)

The spectra of pulsed cathodoluminescence (PCL) of CsI:Tl, YAG:Ge3+,Tb3+, and LFS-3 crystals excited by high-power (˜10 MW) short-time (˜2 ns) action of an electron beam with an average particle energy of ˜150 keV have been compared to the spectra of steady-state luminescence of the same crystals under the action of ?-photons with an energy of 511 keV emitted from a radioactive 22Na sample. It is established that the two spectra are identical, which allows the PCL method to be used for rapid analysis of scintillation crystals.

Zavertyaev, M. V.; Zagumennyi, A. I.; Kozlov, V. A.; Ochkin, V. N.; Pestovskii, N. V.; Petrov, A. A.; Savinov, S. Yu.

2014-05-01

423

Synthetic spectra for terrestrial ultraviolet from discrete measurements  

NASA Astrophysics Data System (ADS)

We describe a rapid inversion algorithm for constructing synthetic terrestrial spectra from measurements made by instruments with multiple narrowband detectors. We show tests of algorithm performance over large dynamic ranges of ozone amount, solar zenith angle, surface albedo, and optical depths of aerosol and clouds. These tests demonstrate that the accuracy of synthetic spectra for total, diffuse, and direct irradiances will be limited by instrument accuracy in almost all cases. Consequently, we show uncertainty analyses for the effects of measurement and calibration errors (including filter wavelength shifts), and the impact of filter wavelength selection on the inverted spectra.

Min, Qilong; Harrison, Lee C.

1998-07-01

424

FT-IR, Raman, and SERS spectra of arcaine sulfate  

SciTech Connect

Vibrational spectral analysis of arcaine sulfate has been carried out using FT-IR, Raman, and SERS spectra. Raman and FT-IR spectra suggest protonation of the imino groups of the arcaine molecule at the expense of the proton from H{sub 2}SO{sub 4}. Analysis of SERS spectra shows that the molecule is adsorbed to the silver surface through the uncharged amino group and oxygen sites of the sulfate groups. The large enhancement observed for the amino group bending vibrations suggests that the molecule is adsorbed perpendicular to the silver surface.

Eapen, A.; Joe, I.H. [Mar Ivanios College, Trivandrum (India)] [Mar Ivanios College, Trivandrum (India); Aruldhas, G. [Regional Research Lab. (CSIR), Trivandrum (India)] [Regional Research Lab. (CSIR), Trivandrum (India)

1997-11-01

425

Analyzer of spectra for Age Determination (ASAD) - algorithm and applications  

NASA Astrophysics Data System (ADS)

Analyzer of Spectra for Age Determination (ASAD) is a new package that can easily predict the age and reddening of stellar clusters from their observed optical integrated spectra by comparing them to synthesis model spectra. The ages obtained with ASAD are consistent with ages obtained from previous cluster age methods requiring a more rigorous and time-consuming analysis. This package not only provides fast results, but also allows the user to comprehend the accuracy of these results by providing surface plots and spectral plots for all combinations of observations and models. ASAD is available for download on the Web and can be immediately used on both Mac and Windows.

Asa'd, Randa S.

2014-12-01

426

Small-world spectra in mean field theory  

E-print Network

Collective dynamics on small-world networks emerge in a broad range of systems with their spectra characterizing fundamental asymptotic features. Here we derive analytic mean field predictions for the spectra of small-world models that systematically interpolate between regular and random topologies by varying their randomness. These theoretical predictions agree well with the actual spectra (obtained by numerical diagonalization) for undirected and directed networks and from fully regular to strongly random topologies. These results may provide analytical insights to empirically found features of dynamics on small-world networks from various research fields, including biology, physics, engineering and social science.

Carsten Grabow; Stefan Grosskinsky; Marc Timme

2011-12-07

427

Extreme ultraviolet emission spectra of Gd and Tb ions  

SciTech Connect

Theoretical extreme ultraviolet emission spectra of gadolinium and terbium ions calculated with the Cowan suite of codes and the flexible atomic code (FAC) relativistic code are presented. 4d-4f and 4p-4d transitions give rise to unresolved transition arrays in a range of ions. The effects of configuration interaction are investigated for transitions between singly excited configurations. Optimization of emission at 6.775 nm and 6.515 nm is achieved for Gd and Tb ions, respectively, by consideration of plasma effects. The resulting synthetic spectra are compared with experimental spectra recorded using the laser produced plasma technique.

Kilbane, D.; O'Sullivan, G. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland)

2010-11-15

428

Ferromagnetic resonance spectra of H2-reduced minerals and glasses  

NASA Technical Reports Server (NTRS)

In an earlier paper, we reported that H2 reduction of basaltic glass, olivine, pyroxene, and plagioclase resulted in the formation of metallic iron, in the darkening and reddening of the reflectance spectra, and the masking of individual spectral features in the visible and near-IR. In this work, we report FMR spectra for H2-reduced minerals and glasses that include the samples studied in the earlier paper. The FMR spectra were reduced at room temperature at a nominal frequency of 9.5 GHz. Sample saturation magnetization reported as F3(0) was measured with a vibrating sample magnetometer.

Morris, Richard V.; Allen, Carlton C.

1994-01-01

429

Direct Analysis of Spectra of Type Ic Supernovae  

E-print Network

Synthetic spectra generated with the parameterized supernova synthetic-spectrum code SYNOW are compared with observed photospheric-phase optical spectra of the normal Type Ic SN 1994I and the peculiar Type Ic SNe 1997ef and 1998bw. The observed spectra can be matched fairly well with synthetic spectra that are based on spherical symmetry and that include lines of just a few ions that are expected to appear on the basis of LTE calculations. Spectroscopic estimates of the mass and kinetic energy of the line-forming layers of the ejected matter give conventional values for SN 1994I but high kinetic energy ($\\sim 30 \\times 10^{51}$ erg) for SN 1997ef and even higher ($\\sim 60 \\times 10^{51}$ erg) for SN 1998bw. It is likely that even if SNe 1997ef and 1998bw were non-spherical, they also were hyper-energetic.

D. Branch

1999-06-09

430

The Fossil Record of Star Formation from Galaxy Spectra   

E-print Network

In this thesis I present work using the MOPED algorithm to extract in a non-parametric fashion star formation histories and galaxy masses from the spectra of galaxies in the Sloan Digital Sky Survey. The recovered ...

Panter, Ben

431

Reflectance Spectra of Members of Very Young Asteroid Families  

NASA Astrophysics Data System (ADS)

We present SpeX infrared spectra for members of the dynamically young Datura, Iannini, Karin, and Veritas asteroid families (plus Koronis and Themis family controls). S-types are space-weathered on timescales of a few million years.

Chapman, C. R.; Enke, B.; Merline, W. J.; Nesvorný, D.; Tamblyn, P.; Young, E. F.

2009-03-01

432

CLASSIFICATION OF STELLAR SPECTRA WITH LOCAL LINEAR EMBEDDING  

SciTech Connect

We investigate the use of dimensionality reduction techniques for the classification of stellar spectra selected from the Sloan Digital Sky Survey. Using local linear embedding (LLE), a technique that preserves the local (and possibly nonlinear) structure within high-dimensional data sets, we show that the majority of stellar spectra can be represented as a one-dimensional sequence within a three-dimensional space. The position along this sequence is highly correlated with spectral temperature. Deviations from this 'stellar locus' are indicative of spectra with strong emission lines (including misclassified galaxies) or broad absorption lines (e.g., carbon stars). Based on this analysis, we propose a hierarchical classification scheme using LLE that progressively identifies and classifies stellar spectra in a manner that requires no feature extraction and that can reproduce the classic MK classifications to an accuracy of one type.

Daniel, Scott F.; Connolly, Andrew; Vanderplas, Jake [Astronomy Department, University of Washington, Box 351580, U.W. Seattle, WA 98195-1580 (United States); Schneider, Jeff; Xiong Liang [School of Computer Science, Carnegie Mellon University, Pittsburgh, PA 15213 (United States)

2011-12-15

433

Infrared transmission spectra of Sea of Fertility regolith  

NASA Technical Reports Server (NTRS)

Transmission spectra in the 2-25 micrometer region were obtained for samples of lunar regolith returned by the Luna 16 automatic station. A comparison of the Luna 16, Apollo 11, and Apollo 12 samples showed that the infrared transmission spectra of regolith samples from the mare regions are similar and characteristic of basic basaltic rocks. The absorption bands show up in the vibration region of the SiO4 groups. No water and OH groups were found in the samples based on the spectrum. Spectra of regolith samples calcined at 1000C showed changes that can be interpreted as changes in the spectra of irradiated crystals (especially distinctly for the Luna 16 samples).

Akhmanova, M. V.; Karyakin, A. V.; Tartasov, L. S.

1974-01-01

434

Microwave spectra of some chlorine and fluorine compounds. [spectroscopic analysis  

NASA Technical Reports Server (NTRS)

A computer-controlled microwave spectrometer was used to catalog reference spectra for chemical analysis. Tables of absorption frequencies, peak absorption intensities, and integrated intensities are shown for 21 organic compounds which contain chlorine, fluorine, or both.

White, W. F.

1975-01-01

435

Power spectra at radio frequency of lightning return stroke waveforms  

NASA Technical Reports Server (NTRS)

The power spectra of the wideband (10 Hz to 100 kHz) magnetic field signals in a number of lightning return strokes (primarily first return strokes) measured during a lightning storm which occurred in Lindau, West Germany in August, 1984 have been calculated. The RF magnetic field data were obtained with the engineering unit of the Galileo Jupiter Probe lightning experiment. The spectra of the magnetic field data definitely show fine structure, with two or three distinct peaks appearing in the spectra of many of the waveforms. An enhancement of power at frequencies of about 60-70 kHz is often seen in the spectra of the waveform time segments preceding and following the rise-to-peak amplitude of the return stroke.

Lanzerotti, L. J.; Thomson, D. J.; Maclennan, C. G.; Rinnert, K.; Krider, E. P.

1989-01-01

436

Composite load spectra for select space propulsion structural components  

NASA Technical Reports Server (NTRS)

The objective of this program is to develop generic load models to simulate the composite load spectra (CLS) that are induced in space propulsion system components representative of the space shuttle main engines (SSME). These models are being developed through describing individual component loads with an appropriate mix of deterministic and state-of-the-art probabilistic models that are related to key generic variables. Combinations of the individual loads are used to synthesize the composite loads spectra. A second approach for developing the composite loads spectra load model simulation, the option portion of the contract will develop coupled models which combine the individual load models. Statistically varying coefficients of the physical models will be used to obtain the composite load spectra.

Newell, J. F.

1987-01-01

437

An extensive library of 2500-10500 Ang synthetic spectra  

E-print Network

We present a complete library of synthetic spectra based on Kurucz's codes that covers the 2500-10500 Ang wavelength range at resolving powers 20,000, 11,500 (GAIA), 8500 (RAVE), 2000 (SLOAN) and uniform dispersions of 1 and 10 Ang/pix. The library maps the whole HR diagram, exploring 51,288 combinations of atmospheric parameters spanning the ranges: 3500 500 K, 0.0 H] 500 km/sec. The spectra are available both as absolute fluxes as well as continuum normalized. Performance tests and foreseen spectroscopic applications of the library are discussed, including automatic classification of data from surveys like RAVE, SLOAN, GAIA. The entire library of synthetic spectra is accessible via http://archives.pd.astro.it/2500-10500/ or (for the 1 AA/pix version only) http://gaia.esa.int/spectralib/spectralib1A/SpectraLib1a.cfm

U. Munari; R. Sordo; F. Castelli; T. Zwitter

2005-02-02

438

FTIR spectra of thin inorganic coatings on metals  

NASA Astrophysics Data System (ADS)

FTIR spectroscopy has been applied in the study of coatings on aluminium, iron and silicon steel sheets. The following coatings have been investigated: on aluminium—oxide, anodic oxide, phosphate and chromate; on iron or steel—oxide, silicate and phosphate. From good quality IR spectra of these coatings much important information has been obtained, for example: quantitative phase composition of the coatings and their structure, metal-coating chemical bonding, mechanism of the coating formation and correlation between coating spectra and their properties. The phenomena and the interpretation of the reflectance IR spectra are discussed, i.e. TO-LO mode splitting for thin coatings and light interference on the sample. The presented FTIR spectra show that these measurement techniques can be applied as a non-destructive research method in different fields of the coating industries and in corrosion science.

Handke, M.; Paluszkiewicz, C.

1984-05-01

439

High-resolution studies of atmospheric IR emission spectra  

NASA Technical Reports Server (NTRS)

Atmospheric emission spectra obtained with two different spectrometer systems are presented. The first system (the BOMEM Michelson interferometer) is designed for emission work. Spectra were obtained under adverse conditions in the Antarctic, and are still of good absolute accuracy. The second system (a modified Bruker Instruments IFS120 very high spectral resolution interferometer) demonstrates the sensitivity that can be achieved even at higher spectral resolution. This system shows that mid-IR atmospheric emission spectra can be obtained with a good SNR in a reasonable length of time at a relatively high resolution. A properly designed high resolution system should achieve high accuracy, sensitivity, and resolution, thereby permitting measurements of many atmospheric constituents when solar spectra cannot be obtained.

Murcray, F. J.; Murcray, F. H.; Goldman, A.; Blatherwick, R. D.; Murcray, D. G.

1991-01-01

440

ACDF molecules data obtained from a spectra fitting method  

NASA Astrophysics Data System (ADS)

Absorption and fluorescence spectra of ACDF molecules dissolved in toluene have been fitted by a procedure previously described. Interesting quantities relatives to these molecules have been obtained from the fitting parameters and comparison with experimental results was made.

Sanchez Gomez, M.; Escudero, J. L.

1986-03-01