Sample records for unbiased moment-rate spectra

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

    NASA Astrophysics Data System (ADS)

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

    2008-11-01

    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

  2. Universal mean moment rate profiles of earthquake ruptures

    SciTech Connect

    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

    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.

  3. Unbiased Longitudinal Processing of

    E-print Network

    Reuter, Martin

    Unbiased Longitudinal Processing of Structural MRI Data Longitudinal image processing procedures in longitudinal image processing, focusing on the introduction of bias, and describe the approaches we have taken to avoid them in the FreeSurfer longitudinal processing stream. Compared with cross-sectional studies

  4. Covariant mutually unbiased bases

    E-print Network

    Claudio Carmeli; Jussi Schultz; Alessandro Toigo

    2015-05-08

    The connection between maximal sets of mutually unbiased bases (MUBs) in a prime-power dimensional Hilbert space and finite phase-space geometries is well known. In this article we classify MUBs according to their degree of covariance with respect to the natural symmetries of a finite phase-space, which are the group of its affine symplectic transformations. We prove that there exist maximal sets of MUBs that are covariant with respect to the full group only in odd prime-power dimensional spaces, and in this case their equivalence class is actually unique. Despite this limitation, we show that in even-prime power dimension covariance can still be achieved by restricting to proper subgroups of the symplectic group, that constitute the finite analogues of the oscillator group. For these subgroups, we explicitly construct the unitary operators yielding the covariance.

  5. Spectra

    NSDL National Science Digital Library

    The Exploratorium

    2012-06-26

    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.

  6. Spectra

    NSDL National Science Digital Library

    Kaler, James B.

    Spectra is a website illustrating how astronomers use spectra to understand what stars are made of, their structures, and their evolution. The page begins with an introduction to the electromagnetic spectrum and then goes into detail about the properties of light. Then it discusses how matter both creates and destroys radiation. It goes on to interpret absorption and emission lines. The website ends with discussing how astronomers use spectra to understand stars, galaxies, and other objects in the universe.

  7. Constraining the Moment Rate Budget for Continental Alaska by Combining Geologic and Earthquake Productivity Rate Data

    NASA Astrophysics Data System (ADS)

    Klein, E. C.; Kreemer, C. W.

    2011-12-01

    As part of the Global Earthquake Model (GEM) project (www.globalquakemodel.org), there is a need for geodetically constrained, high-resolution, strain rate models of plate boundary zones. These models can be used to assess the completeness of the moment rate budget implied by Quaternary faulting data bases and earthquake productivity rates, which are the typical foundations of any seismic hazard model. The ultimate goal is to create strain rate models that best satisfy the geodetic, geologic, and seismic observations simultaneously. Such models could reveal any significant discrepancy between Quaternary faulting slip rates and geodetic observations, and could constrain the maximum expected magnitude in light of a Gutenberg-Richter or Characteristic Earthquake distribution of seismicity. One limitation of kinematic models heavily reliant on geodetic data, is that they may suffer from uncertainties arising from difficult to remove postseismic and interseismic transient affects. To better understand the role of the interseismic strain field and how it relates to seismic hazard motivates the need for a longer-term kinematic estimate. We present long-term strain rate models for continental Alaska based on geologic and seismic observations. When solving for a continuous velocity gradient tensor field we use seismic and geologic data as apriori constraints on the strain rate model covariance matrix. For the a priori strain rate variances, we use Quaternary fault slip rates from Finzel et al. [2011], and for all "non-faulting" cells of our model grid we combine unit summed moment tensors with strain rates associated with the moment release rate given an area's a- and b-value and assumed maximum moment. Because the majority of the seismicity occurs in central and southern Alaska, we divide the plate boundary zone into two seismologically distinct regions and determine the Characteristic Earthquake distribution for each region separately. Using a plate velocity of 51 mm/a, a seismogenic thickness of 20 km, and a shear modulus of 30 GPa, we will show that the total moment rate for the plate boundary zone is approximately 84.8 * 1018 Nm/a and that "off-fault" seismicity accounts for about 40% of this moment rate. Given a plate velocity of 51 mm/a necessitates that the quaternary fault interfaces take up roughly 31 mm/a of slip. In addition to this preliminary result, we will show results for our preferred model, as well as the strain rate models that are based on either the geologic or seismic data alone. We will discuss the significant differences between these models in terms of using these data sets in seismic hazard modeling.

  8. Construction of mutually unbiased bases in

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Tao, Yuan-Hong; Nan, Hua; Fei, Shao-Ming

    2015-07-01

    We study mutually unbiased bases in . A systematic way of constructing mutually unbiased maximally entangled bases (MUMEBs) in from MUMEBs in and a general approach to construct mutually unbiased unextendible maximally entangled bases (MUUMEBs) in from MUUMEBs in have been presented. Detailed examples are given.

  9. Stress states and moment rates of a two-asperity fault in the presence of viscoelastic relaxation

    NASA Astrophysics Data System (ADS)

    Dragoni, M.; Lorenzano, E.

    2015-06-01

    A fault containing two asperities with different strengths is considered. The fault is embedded in a shear zone subject to a constant strain rate by the motions of adjacent tectonic plates. The fault is modelled as a discrete dynamical system where the average values of stress, friction and slip on each asperity are considered. The state of the fault is described by three variables: the slip deficits of the asperities and the viscoelastic deformation. The system has four dynamic modes, for which analytical solutions are calculated. The relationship between the state of the fault before a seismic event and the sequence of slipping modes in the event is enlightened. Since the moment rate depends on the number and sequence of slipping modes, the knowledge of the source function of an earthquake constrains the orbit of the system in the phase space. If the source functions of a larger number of consecutive earthquakes were known, the orbit could be constrained more and more and its evolution could be predicted with a smaller uncertainty. The model is applied to the 1964 Alaska earthquake, which was the effect of the failure of two asperities and for which a remarkable post-seismic relaxation has been observed in the subsequent decades. The evolution of the system after the 1964 event depends on the state from which the event was originated, that is constrained by the observed moment rate. The possible durations of the interseismic interval and the possible moment rates of the next earthquake are calculated as functions of the initial state.

  10. Stress states and moment rates of a two-asperity fault in the presence of viscoelastic relaxation

    NASA Astrophysics Data System (ADS)

    Dragoni, M.; Lorenzano, E.

    2015-02-01

    A fault containing two asperities with different strengths is considered. The fault is embedded in a viscoelastic shear zone, subject to a constant strain rate by the motions of adjacent tectonic plates. The fault is modelled as a discrete dynamical system where the average values of stress, friction and slip on each asperity are considered. The state of the fault is described by three variables: the slip deficits of the asperities and the viscoelastic deformation. The system has four dynamic modes, for which the analytical solutions are calculated. The relationship between the state of the fault before a seismic event and the sequence of slipping modes in the event is enlightened. Since the moment rate depends on the number and sequence of slipping modes, the knowledge of the source function of an earthquake constrains the orbit of the system in the phase space. If the source functions of a larger number of consecutive earthquakes were known, the orbit could be constrained more and more and its evolution could be predicted with a smaller uncertainty. The model is applied to the 1964 Alaska earthquake, which was the effect of the failure of two asperities and for which a remarkable postseismic relaxation has been observed in the subsequent decades. The evolution of the system after the 1964 event depends on the state from which the event was originated, that is constrained by the observed moment rate. The possible durations of the interseismic interval and the possible moment rates of the next earthquake are calculated as functions of the initial state.

  11. Unbiased stratification of left ventricles.

    PubMed

    Srinivasan, Rajagopalan; Shriram, K S; Suryanarayanan, Srikanth

    2008-01-01

    Image based quantitative stratification of the Left Ventricles (LV) across a population helps in unraveling the structure-function symbiosis of the heart. An unbiased, reference less grouping scheme that automatically determines the number of clusters and a physioanatomically relevant strategy that aligns the intra cluster LV shapes would enable the robust construction of pathology stratified cardiac atlas. This paper achieves this hitherto elusive stratification and alignment by adapting the conventional strategies routinely followed by clinicians. The individual LV shape models (N=127) are independently oriented to an "attitudinally consistent orientation" that captures the physioanatomic variations of the LV morphology. Affinity propagation technique based on the automatically identified inter-LV_landmark distances is used to group the LV shapes. The proposed algorithm is computationally efficient and, if the inter cluster variations are linked to pathology, could provide a clinically relevant cardiac atlas. PMID:18979790

  12. Affine Constellations Without Mutually Unbiased Counterparts

    E-print Network

    Stefan Weigert; Thomas Durt

    2010-07-22

    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.

  13. A SPITZER UNBIASED ULTRADEEP SPECTROSCOPIC SURVEY

    SciTech Connect

    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

    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.

  14. Classifying all mutually unbiased bases in Rel

    E-print Network

    Julia Evans; Ross Duncan; Alex Lang; Prakash Panangaden

    2009-09-25

    Finding all the mutually unbiased bases in various dimensions is a problem of fundamental interest in quantum information theory and pure mathematics. The general problem formulated in finite-dimensional Hilbert spaces is open. In the categorical approach to quantum mechanics one can find examples of categories which behave ``like'' the category of finite-dimensional Hilbert spaces in various ways but are subtly different. One such category is the category of sets and relations, $\\mathbf{Rel}$. One can formulate the concept of mutually unbiased bases here as well. In this note we classify all the mutually unbiased bases in this category by relating it to a standard question in combinatorics.

  15. Mutually unbiased bases with free parameters

    E-print Network

    Dardo Goyeneche; Santiago Gomez

    2015-06-27

    We present a systematic method to introduce free parameters in sets of mutually unbiased bases. In particular, we demonstrate that any set of m real mutually unbiased bases in dimension N>2 admits the introduction of (m-1)N/2 free parameters which cannot be absorbed by a global unitary operation. As consequence, there are m=k+1 mutually unbiased bases in every dimension N=k^2 with k^3/2 free parameters, where k is even. We construct the maximal set of triplets of mutually unbiased bases for two-qubits systems and triplets, quadruplets and quintuplets of mutually unbiased bases with free parameters for three-qubits systems. Furthermore, we study the richness of the entanglement structure of such bases and we provide the quantum circuits required to implement all these bases with free parameters in the laboratory. Finally, we find the upper bound for the maximal number of real and complex mutually unbiased bases existing in every dimension. This proof is simple, short and it considers basic matrix algebra.

  16. Improving spatial resolution of the moment rate function in regions of high slip determined from finite fault inversions

    NASA Astrophysics Data System (ADS)

    Adams, M.; Ji, C.; Archuleta, R. J.

    2014-12-01

    Finite fault inversions attempt to resolve the spatial distribution of the moment rate function per unit area using seismic observations. However, the observational and synthetic limitations that exist due to the station distribution and frequency content of signals that can be modeled imply that various simplifications to the source representation need to be made in order to stabilize the inversions. These simplifications inevitably affect the final results, though it is largely unknown how serious the regularization can be. Here, we explore the effects caused by a pre-assumed slip rate function using synthetic data from the Source Inversion Validation (SIV) produced by a crack-like spontaneous dynamic rupture embedded in a layered, elastic medium. Thus we have exact Green's functions, which allow us to consider only the effects of varying the slip rate function. We study the effect of three different inverted slip rate functions: i) asymmetric cosine functions; ii) modified Yoffe functions and iii) no negative functions within given time windows. The first approach has been used routinely in finite fault inversions and the second one is characteristic of dynamic simulations. We perform the inversions using the first two cases with a simulated annealing algorithm and attempt to answer whether the ideal synthetic data can differentiate between them. The last one has the inverted slip rate function with the least a priori constraints but uses many more free parameters. It is inverted using the newly developed Projected Landweber (PL) method and we will explore its dependence on the choice of the initial model and the bandwidth of signals.

  17. Unbiased Look at Dataset Bias Antonio Torralba

    E-print Network

    Guestrin, Carlos

    Unbiased Look at Dataset Bias Antonio Torralba Massachusetts Institute of Technology torralba@csail.mit.edu Alexei A. Efros Carnegie Mellon University efros@cs.cmu.edu Abstract Datasets are an integral part and comparing performance of competing algo- rithms. At the same time, datasets have often been blamed

  18. Best Linear Unbiased Estimate Motivation for BLUE

    E-print Network

    Fowler, Mark

    1 Chapter 6 Best Linear Unbiased Estimate (BLUE) #12;2 Motivation for BLUE Except for Linear Model to a sub-optimal estimate BLUE is one such sub-optimal estimate Idea for BLUE: 1. Restrict estimate) Advantage of BLUE:Needs only 1st and 2nd moments of PDF Mean & Covariance Disadvantages of BLUE: 1. Sub

  19. Arithmetic, mutually unbiased bases and complementary observables

    NASA Astrophysics Data System (ADS)

    Sheppeard, M. D.

    2010-02-01

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

  20. A geometrical relation between symmetric operators and mutually unbiased operators

    E-print Network

    Amir Kalev

    2013-05-26

    In this work we study the relation between the set of symmetric operators and the set of mutually unbiased operators from finite plane geometry point of view. Here symmetric operators are generalization of symmetric informationally complete probability-operator measurements (SIC POMs), while mutually unbiased operators are the operator generalization of mutually unbiased bases (MUB). We also discuss the implication of this relation to the particular cases of rank-1 SIC POMs and MUB.

  1. Decision rules for unbiased inventory estimates

    NASA Technical Reports Server (NTRS)

    Argentiero, P. D.; Koch, D.

    1979-01-01

    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.

  2. Study of stochastic estimates of quark loops with unbiased subtraction

    Microsoft Academic Search

    Nilmani Mathur; Shao-Jing Dong

    2003-01-01

    Stochastic noise estimator method is a powerful tool to calculate the disconnected insertion involving quark loops. We study the variance reduction technique with unbiased subtraction. We use the complexZ2 noise to calculate the quark loops on a 163 × 24 lattice with ? = 6.0 and ? = 0.154. Unbiased subtraction method is performed by using hoping parameter expansion. We

  3. Best Unbiased Estimation in Unbalanced Split Plot Designs

    Microsoft Academic Search

    Shaun S. Wulff

    2005-01-01

    Best unbiased estimation is considered for linear combinations of cell means and for variance components in unbalanced split plot designs in which the whole plots have a randomized complete block design or a completely randomized design. The conditions for existence of best unbiased estimators are expressed in terms of the number of observations in the whole plot, subplot, and block

  4. Building unbiased estimators from non-gaussian likelihoods with application to shear estimation

    SciTech Connect

    Madhavacheril, Mathew S. [Stony Brook Univ., NY (United States); Slosar, Anze [Brookhaven National Lab. (BNL), Upton, NY (United States); McDonald, Patrick [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sehgal, Neelima [Stony Brook Univ., NY (United States)

    2015-01-01

    We develop a general framework for generating estimators of a given quantity which are unbiased to a given order in the difference between the true value of the underlying quantity and the fiducial position in theory space around which we expand the likelihood. We apply this formalism to rederive the optimal quadratic estimator and show how the replacement of the second derivative matrix with the Fisher matrix is a generic way of creating an unbiased estimator (assuming choice of the fiducial model is independent of data). Next we apply the approach to estimation of shear lensing, closely following the work of Bernstein and Armstrong (2014). Our first order estimator reduces to their estimator in the limit of zero shear, but it also naturally allows for the case of non-constant shear and the easy calculation of correlation functions or power spectra using standard methods. Both our first-order estimator and Bernstein and Armstrong’s estimator exhibit a bias which is quadratic in true shear. Our third-order estimator is, at least in the realm of the toy problem of Bernstein and Armstrong, unbiased to 0.1% in relative shear errors ?g/g for shears up to |g| = 0.2.

  5. Building unbiased estimators from non-gaussian likelihoods with application to shear estimation

    DOE PAGESBeta

    Madhavacheril, Mathew S.; Slosar, Anze; McDonald, Patrick; Sehgal, Neelima

    2015-01-01

    We develop a general framework for generating estimators of a given quantity which are unbiased to a given order in the difference between the true value of the underlying quantity and the fiducial position in theory space around which we expand the likelihood. We apply this formalism to rederive the optimal quadratic estimator and show how the replacement of the second derivative matrix with the Fisher matrix is a generic way of creating an unbiased estimator (assuming choice of the fiducial model is independent of data). Next we apply the approach to estimation of shear lensing, closely following the workmore »of Bernstein and Armstrong (2014). Our first order estimator reduces to their estimator in the limit of zero shear, but it also naturally allows for the case of non-constant shear and the easy calculation of correlation functions or power spectra using standard methods. Both our first-order estimator and Bernstein and Armstrong’s estimator exhibit a bias which is quadratic in true shear. Our third-order estimator is, at least in the realm of the toy problem of Bernstein and Armstrong, unbiased to 0.1% in relative shear errors ?g/g for shears up to |g| = 0.2.« less

  6. Building unbiased estimators from non-Gaussian likelihoods with application to shear estimation

    NASA Astrophysics Data System (ADS)

    Madhavacheril, Mathew S.; McDonald, Patrick; Sehgal, Neelima; Slosar, Anže

    2015-01-01

    We develop a general framework for generating estimators of a given quantity which are unbiased to a given order in the difference between the true value of the underlying quantity and the fiducial position in theory space around which we expand the likelihood. We apply this formalism to rederive the optimal quadratic estimator and show how the replacement of the second derivative matrix with the Fisher matrix is a generic way of creating an unbiased estimator (assuming choice of the fiducial model is independent of data). Next we apply the approach to estimation of shear lensing, closely following the work of Bernstein and Armstrong (2014). Our first order estimator reduces to their estimator in the limit of zero shear, but it also naturally allows for the case of non-constant shear and the easy calculation of correlation functions or power spectra using standard methods. Both our first-order estimator and Bernstein and Armstrong's estimator exhibit a bias which is quadratic in true shear. Our third-order estimator is, at least in the realm of the toy problem of Bernstein and Armstrong, unbiased to 0.1% in relative shear errors ?g/g for shears up to |g|=0.2.

  7. Cyclic mutually unbiased bases, Fibonacci polynomials and Wiedemann's conjecture

    NASA Astrophysics Data System (ADS)

    Seyfarth, Ulrich; Ranade, Kedar S.

    2012-06-01

    We relate the construction of a complete set of cyclic mutually unbiased bases, i.e., mutually unbiased bases generated by a single unitary operator, in power-of-two dimensions to the problem of finding a symmetric matrix over {F}_2 with an irreducible characteristic polynomial that has a given Fibonacci index. For dimensions of the form 2^{2^k}, we present a solution that shows an analogy to an open conjecture of Wiedemann in finite field theory. Finally, we discuss the equivalence of mutually unbiased bases.

  8. Unbiased Inclination Distributions for Objects in the Kuiper Belt

    E-print Network

    Gulbis, Amanda A. S.

    Using data from the Deep Ecliptic Survey (DES), we investigate the inclination distributions of objects in the Kuiper Belt. We present a derivation for observational bias removal and use this procedure to generate unbiased ...

  9. Unbiased Estimation in a Closed Sequential Testing Procedure.

    ERIC Educational Resources Information Center

    Wilcox, Rand R.

    1983-01-01

    This article provides unbiased estimates of the proportion of items in an item domain that an examinee would answer correctly if every item were attempted, when a closed sequential testing procedure is used. (Author)

  10. On Unbiased Estimation of Sparse Vectors Corrupted by Gaussian Noise

    Microsoft Academic Search

    Alexander Jung; Zvika Ben-Haim; Franz Hlawatsch; Yonina C. Eldar

    2010-01-01

    We consider the estimation of a sparse parameter vector from measurements\\u000acorrupted by white Gaussian noise. Our focus is on unbiased estimation as a\\u000asetting under which the difficulty of the problem can be quantified\\u000aanalytically. We show that there are infinitely many unbiased estimators but\\u000anone of them has uniformly minimum mean-squared error. We then provide lower\\u000aand upper

  11. Concepts and Hypotheses Search-based Learning Unbiased Learning Concept Learning

    E-print Network

    Kjellström, Hedvig

    Concepts and Hypotheses Search-based Learning Unbiased Learning Concept Learning #12;Concepts and Hypotheses Search-based Learning Unbiased Learning 1 Concepts and Hypotheses Definitions Example Hypotheses 2 Search-based Learning Find-S List-then-Eliminate Candidate Elimination 3 Unbiased Learning Bias Unbiased

  12. Concepts and Hypotheses Search-based Learning Unbiased Learning Concept Learning

    E-print Network

    Kjellström, Hedvig

    Concepts and Hypotheses Search-based Learning Unbiased Learning Concept Learning Concepts and Hypotheses Search-based Learning Unbiased Learning 1 Concepts and Hypotheses Definitions Example Hypotheses 2 Search-based Learning Find-S List-then-Eliminate Candidate Elimination 3 Unbiased Learning Bias Unbiased

  13. Entanglement patterns in mutually unbiased basis sets

    SciTech Connect

    Lawrence, Jay [Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755 (United States) and The James Franck Institute, University of Chicago, Chicago, Illinois 60637 (United States)

    2011-08-15

    A few simply stated rules govern the entanglement patterns that can occur in mutually unbiased basis sets (MUBs) and constrain the combinations of such patterns that can coexist in full complements of MUBs. We consider Hilbert spaces of prime power dimensions (D=p{sup N}), as realized by systems of N prime-state particles, where full complements of D+1 MUBs are known to exist, and we assume only that MUBs are eigenbases of generalized Pauli operators, without using any particular construction. The general rules include the following: (1) In any MUB, a given particle appears either in a pure state or totally entangled and (2) in any full MUB complement, each particle is pure in (p+1) bases (not necessarily the same ones) and totally entangled in the remaining (p{sup N}-p). It follows that the maximum number of product bases is p+1 and, when this number is realized, all remaining (p{sup N}-p) bases in the complement are characterized by the total entanglement of every particle. This ''standard distribution'' is inescapable for two-particle systems (of any p), where only product and generalized Bell bases are admissible MUB types. This and the following results generalize previous results for qubits [Phys. Rev. A 65. 032320 (2002); Phys. Rev. A 72, 062310 (2005)] and qutrits [Phys. Rev. A 70, 012302 (2004)], drawing particularly upon [Phys. Rev. A 72, 062310 (2005)]. With three particles there are three MUB types, and these may be combined in (p+2) different ways to form full complements. With N=4, there are 6 MUB types for p=2, but new MUB types become possible with larger p, and these are essential to realizing full complements. With this example, we argue that new MUB types that show new entanglement patterns should enter with every step in N and, also, when N is a prime plus 1, at a critical p value, p=N-1. Such MUBs should play critical roles in filling complements.

  14. Unbiased diffusion of Brownian particles on disordered correlated potentials

    NASA Astrophysics Data System (ADS)

    Salgado-Garcia, Raúl; Maldonado, Cesar

    2015-06-01

    In this work we study the diffusion of non-interacting overdamped particles, moving on unbiased disordered correlated potentials, subjected to Gaussian white noise. We obtain an exact expression for the diffusion coefficient which allows us to prove that the unbiased diffusion of overdamped particles on a random polymer does not depend on the correlations of the disordered potentials. This universal behavior of the unbiased diffusivity is a direct consequence of the validity of the Einstein relation and the decay of correlations of the random polymer. We test the independence on correlations of the diffusion coefficient for correlated polymers produced by two different stochastic processes, a one-step Markov chain and the expansion-modification system. Within the accuracy of our simulations, we found that the numerically obtained diffusion coefficient for these systems agree with the analytically calculated ones, confirming our predictions.

  15. Study of stochastic estimates of quark loops with unbiased subtraction

    E-print Network

    Mathur, N; Mathur, Nilmani; Dong, Shao-Jing

    2002-01-01

    Stochastic noise estimator method is a powerful tool to calculate the disconnected insertion involving quark loops. We study the variance reduction technique with unbiased subtraction. We use the complex $Z_2$ noise to calculate the quark loops on a $16^3 \\times 24$ lattice with $\\beta = 6.0$ and $\\kappa$ = 0.154. Unbiased subtraction method is performed by using hoping parameter expansion. We report on the variance reduction for the point-split vector current as a function of the number of subtraction terms and the number of noise used.

  16. Study of stochastic estimates of quark loops with unbiased subtraction

    E-print Network

    Nilmani Mathur; Shao-Jing Dong

    2002-09-04

    Stochastic noise estimator method is a powerful tool to calculate the disconnected insertion involving quark loops. We study the variance reduction technique with unbiased subtraction. We use the complex $Z_2$ noise to calculate the quark loops on a $16^3 \\times 24$ lattice with $\\beta = 6.0$ and $\\kappa$ = 0.154. Unbiased subtraction method is performed by using hoping parameter expansion. We report on the variance reduction for the point-split vector current as a function of the number of subtraction terms and the number of noise used.

  17. Stable and unbiased flow turbulence estimation from pulse echo ultrasound

    Microsoft Academic Search

    Yi Zheng; James F. Greenleaf

    1999-01-01

    A new method for stable and unbiased flow turbulence estimation has been developed for medical ultrasonic color flow imaging. Conventional turbulence estimates from a finite number of transmitted pulses could be biased, unreliable, and erroneous. We found that a conventional method cannot provide quantitative estimates of variance of flow velocity. We propose a new approach for flow turbulence estimation that

  18. Minimum variance quadratic unbiased estimation of variance components

    Microsoft Academic Search

    C. Radhakrishna Rao

    1971-01-01

    The variance of a quadratic function of the random variables in a linear model is minimized to obtain locally best unbiased estimators (MIVQUE) of variance components. Condition for such estimators to be independent of the kurtosis of the variables is given. When the variables are normally distributed, MIVQUE coincides with MINQUE under the Euclidean norm of a matrix. Conditions under

  19. BEST UNBIASED LINEAR ESTIMATION, A COORDINATE FREE APPROACH

    Microsoft Academic Search

    S. GNOT; W. ZMYSLONY

    This paper gives further developments of the theory of uniformly minimum variance unbiased estimation (UMVUE) in Euclidean rector spaces as originated by W. Kruskal, G. Zyskind and J. Seely. It gives necessary and sufficient conditions for the existence of a UMVUE for each estimable function in any subspace of linear estimators with no restrictions posed on the covariance operators. Also

  20. Unbiased Online Active Learning in Data Streams Redmond, WA, USA

    E-print Network

    Wei, Chu

    Unbiased Online Active Learning in Data Streams Wei Chu Microsoft Redmond, WA, USA chu online to estimate param- eters. In empirical evaluation, we collect a data stream of user-stationary situation with concept drift. Categories and Subject Descriptors G.3 [Probabilities and Statistics

  1. Multi-scale Unbiased Diffeomorphic Atlas Construction on , Jens Kruger

    E-print Network

    Silva, Claudio T.

    structures. This average serves as a deformable template which maps detailed atlas data such as structural mapping from the atlas to the target can be used to study the physical properties of the target anatomyMulti-scale Unbiased Diffeomorphic Atlas Construction on Multi-GPUs Linh Ha , Jens Kr¨uger Sarang

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

    E-print Network

    Van Den Eijnden, Eric

    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

  3. Unbiased Branches: An Open Problem Arpad Gellert1

    E-print Network

    Vintan, Lucian N.

    Unbiased Branches: An Open Problem Arpad Gellert1 , Adrian Florea1 , Maria Vintan1 , Colin Egan2 , and Lucian Vintan1 1 Computer Science Department, "Lucian Blaga" University of Sibiu, Emil Cioran Street, No of Computer Science, University of Hertfordshire, Hatfield, College Lane, AL10 9AB UK, c

  4. X-ray properties of an Unbiased Hard X-ray Detected Sample of AGN

    E-print Network

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

    2007-10-31

    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 (14-195 keV). In this paper, we present for the first time {\\it XMM-Newton} X-ray spectra for 22 BAT AGNs 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$_H = 0.03$), AGN sample. We find 9/22 low absorption (n$_H 2.0$ keV. Five of the complex sources are classified as Compton-thick candidates. Further, we find four more sources with properties consistent with the hidden/buried AGN reported by Ueda {\\it et al.} (2007). Finally, we include a comparison of the {\\it XMM-Newton} 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.

  5. A cramer-Rao analogue for median-unbiased estimators

    Microsoft Academic Search

    N. K. Sung; G. Stangenhaus; H. T. David

    1990-01-01

    Summary  Adopting a measure of dispersion proposed by Alamo [1964], and extending the analysis in Stangenhaus [1977] and Stangenhaus\\u000a and David [1978b], an analogue of the classical Cramér-Rao lower bound for median-unbiased estimators is developed for absolutely\\u000a continuous distributions with a single parameter, in which mean-unbiasedness, the Fisher information, and the variance are\\u000a replaced by median-unbiasedness, the first absolute moment of

  6. Unbiased estimators for spatial distribution functions of classical fluids.

    PubMed

    Adib, Artur B; Jarzynski, Christopher

    2005-01-01

    We use a statistical-mechanical identity closely related to the familiar virial theorem, to derive unbiased estimators for spatial distribution functions of classical fluids. In particular, we obtain estimators for both the fluid density rho(r) in the vicinity of a fixed solute and the pair correlation g(r) of a homogeneous classical fluid. We illustrate the utility of our estimators with numerical examples, which reveal advantages over traditional histogram-based methods of computing such distributions. PMID:15638649

  7. Encryption via Entangled states belonging to Mutually Unbiased Bases

    E-print Network

    M. Revzen; F. C. Khanna

    2008-09-11

    We consider particular entanglement of two particles whose state vectors are in bases that are mutually unbiased (MUB), i.e. "that exhibit maximum degree of incompatibility" (J.Schwinger,Nat. Ac. Sci. (USA), 1960)). We use this link between entanglement and MUB to outline a protocol for secure key distribution among the parties that share these entangled states. The analysis leads to an association of entangled states and states in an MUB set: both carry the same labels.

  8. Unbiased water and methanol maser surveys of NGC 1333

    SciTech Connect

    Lyo, A-Ran; Kim, Jongsoo; Byun, Do-Young; Lee, Ho-Gyu, E-mail: arl@kasi.re.kr [Korea Astronomy and Space Science Institute, 776, Daedeokdae-ro Yuseong-gu, Daejeon 305-348 (Korea, Republic of)

    2014-11-01

    We present the results of unbiased 22 GHz H{sub 2}O water and 44 GHz class I CH{sub 3}OH 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 H{sub 2}O(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{sup –1}, which are blue- and redshifted relative to the adopted systemic velocity of ?7 km s{sup –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 × 10{sup 25} erg s{sup –1} from our unbiased survey.

  9. Acceleration spectra for subduction zone earthquakes

    USGS Publications Warehouse

    Boatwright, J.; Choy, G.L.

    1989-01-01

    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

  10. Unbiased Monte Carlo for the age of tensor networks

    E-print Network

    Ferris, Andrew J

    2015-01-01

    A new unbiased Monte Carlo technique called Tensor Network Monte Carlo (TNMC) is introduced based on sampling all possible renormalizations (or course-grainings) of tensor networks, in this case matrix-product states. Tensor networks are a natural language for expressing a wide range of discrete physical and statistical problems, such as classical and quantum systems on a lattice at thermal equilibrium. By simultaneously sampling multiple degrees of freedom associated with each bond of the tensor network (and its renormalized form), we can achieve unprecedented low levels of statistical fluctuations which simultaneously parallel the impressive accuracy scaling of tensor networks while avoiding completely the variational bias inherent to those techniques, even with small bond dimensions. The resulting technique is essentially an aggressive multi-sampling technique that can account for the great majority of the partition function in a single sample. The method is quite general and can be combined with a variety...

  11. All-optical injection of ballistic electrical currents in unbiased silicon

    E-print Network

    Loss, Daniel

    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

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

    E-print Network

    Markopoulou, Athina

    Walking in Facebook: A Case Study of Unbiased Sampling of OSNs Minas Gjoka Networked Systems UC of Facebook users by crawling its social graph. In this quest, we consider and implement several candidate to the best of our knowledge unbiased sample of Facebook. Finally, we use one of our representative datasets

  13. Stein Unbiased GrAdient estimator of the Risk (SUGAR) for multiple parameter selection

    E-print Network

    Paris-Sud XI, Université de

    Stein Unbiased GrAdient estimator of the Risk (SUGAR) for multiple parameter selection Charles gradient, coined the Stein Unbiased GrAdient estimator of the Risk (SUGAR), provides an asymptotically, in the particular case of soft- thresholding, the SUGAR is proved to be also a consistent estimator. The SUGAR can

  14. MUSE: Robust Surface Fitting using Unbiased Scale Estimates James V. Miller \\Lambda Charles V. Stewart

    E-print Network

    ­ quentially extract multiple surfaces from an image region. We show MUSE to be effective on synthetic dataMUSE: Robust Surface Fitting using Unbiased Scale Estimates James V. Miller \\Lambda Charles V­ tor, called MUSE (Minimum Unbiased Scale Estimator), evaluates a hypothesized fit over potential

  15. MUSE: Robust Surface Fitting using Unbiased Scale Estimates James V. Miller Charles V. Stewart

    E-print Network

    - quentially extract multiple surfaces from an image region. We show MUSE to be effective on synthetic dataMUSE: Robust Surface Fitting using Unbiased Scale Estimates James V. Miller Charles V. Stewart- tor, called MUSE (Minimum Unbiased Scale Estimator), evaluates a hypothesized fit over potential

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

    SciTech Connect

    Shalaby, M.; Vourdas, A., E-mail: a.vourdas@bradford.ac.uk

    2013-10-15

    Quantum systems with variables in the ring Z(d) are considered, and the concepts of weak mutually unbiased bases and mutually unbiased projectors are discussed. The lines through the origin in the Z(d)×Z(d) phase space, are classified into maximal lines (sets of d points), and sublines (sets of d{sub i} points where d{sub i}|d). The sublines are intersections of maximal lines. It is shown that there exists a duality between the properties of lines (resp., sublines), and the properties of weak mutually unbiased bases (resp., mutually unbiased projectors). -- Highlights: •Lines in discrete phase space. •Bases in finite quantum systems. •Duality between bases and lines. •Weak mutually unbiased bases.

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

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

    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.

  18. Building an unbiased sample of quiescent galaxies up to z=2.5 based on the Mg(UV) absorption index

    NASA Astrophysics Data System (ADS)

    Domínguez Sánchez, H.; Carmen Eliche-Moral, M.; Pérez-González, P. G.; Esquej, P.; Alcalde-Pampliega, B.; SHARDS Team

    2015-05-01

    Samples of ``red & dead" galaxies selected through traditional color-based techniques usually suffer from contamination by strongly dust obscured sources. We are using GTC/OSIRIS data from the SHARDS project on the GOODSN field to define unbiased samples of really quiescent massive galaxies at different redshifts up to z=2.5. By measuring the Mg(UV) absorption index in the pseudo-spectra of these galaxies, we intend to determine the redshift evolution of the characteristic age of their stellar populations to shed some light into their assembly epoch.

  19. Mutually unbiased bases as minimal Clifford covariant 2-designs

    NASA Astrophysics Data System (ADS)

    Zhu, Huangjun

    2015-06-01

    Mutually unbiased bases (MUBs) are interesting for various reasons. The most attractive example of (a complete set of) MUBs is the one constructed by Ivanovi? as well as Wootters and Fields, which is referred to as the canonical MUB. Nevertheless, little is known about anything that is unique to this MUB. We show that the canonical MUB in any prime power dimension is uniquely determined by an extremal orbit of the (restricted) Clifford group except in dimension 3, in which case the orbit defines a special symmetric informationally complete measurement (SIC), known as the Hesse SIC. Here the extremal orbit is the orbit with the smallest number of pure states. Quite surprisingly, this characterization does not rely on any concept that is related to bases or unbiasedness. As a corollary, the canonical MUB is the unique minimal 2-design covariant with respect to the Clifford group except in dimension 3. In addition, these MUBs provide an infinite family of highly symmetric frames and positive-operator-valued measures (POVMs), which are of independent interest.

  20. All-optical control of ultrafast photocurrents in unbiased graphene

    PubMed Central

    Obraztsov, Petr A.; Kaplas, Tommi; Garnov, Sergey V.; Kuwata-Gonokami, Makoto; Obraztsov, Alexander N.; Svirko, Yuri P.

    2014-01-01

    Graphene has recently become a unique playground for studying light-matter interaction effects in low-dimensional electronic systems. Being of strong fundamental importance, these effects also open a wide range of opportunities in photonics and optoelectronics. In particular, strong and broadband light absorption in graphene allows one to achieve high carrier densities essential for observation of nonlinear optical phenomena. Here, we make use of strong photon-drag effect to generate and optically manipulate ultrafast photocurrents in graphene at room temperature. In contrast to the recent reports on injection of photocurrents in graphene due to external or built-in electric field effects and by quantum interference, we force the massless charge carriers to move via direct transfer of linear momentum from photons of incident laser beam to excited electrons in unbiased sample. Direction and amplitude of the drag-current induced in graphene are determined by polarization, incidence angle and intensity of the obliquely incident laser beam. We also demonstrate that the irradiation of graphene with two laser beams of the same wavelength offers an opportunity to manipulate the photocurrents in time domain. The obtained all-optical control of the photocurrents opens new routes towards graphene based high-speed and broadband optoelectronic devices. PMID:24500084

  1. All-optical control of ultrafast photocurrents in unbiased graphene.

    PubMed

    Obraztsov, Petr A; Kaplas, Tommi; Garnov, Sergey V; Kuwata-Gonokami, Makoto; Obraztsov, Alexander N; Svirko, Yuri P

    2014-01-01

    Graphene has recently become a unique playground for studying light-matter interaction effects in low-dimensional electronic systems. Being of strong fundamental importance, these effects also open a wide range of opportunities in photonics and optoelectronics. In particular, strong and broadband light absorption in graphene allows one to achieve high carrier densities essential for observation of nonlinear optical phenomena. Here, we make use of strong photon-drag effect to generate and optically manipulate ultrafast photocurrents in graphene at room temperature. In contrast to the recent reports on injection of photocurrents in graphene due to external or built-in electric field effects and by quantum interference, we force the massless charge carriers to move via direct transfer of linear momentum from photons of incident laser beam to excited electrons in unbiased sample. Direction and amplitude of the drag-current induced in graphene are determined by polarization, incidence angle and intensity of the obliquely incident laser beam. We also demonstrate that the irradiation of graphene with two laser beams of the same wavelength offers an opportunity to manipulate the photocurrents in time domain. The obtained all-optical control of the photocurrents opens new routes towards graphene based high-speed and broadband optoelectronic devices. PMID:24500084

  2. An Unbiased Hessian Representation for Monte Carlo PDFs

    E-print Network

    Carrazza, Stefano; Kassabov, Zahari; Latorre, Jose Ignacio; Rojo, Juan

    2015-01-01

    We develop a methodology for the construction of a Hessian representation of Monte Carlo sets of parton distributions, based on the use of a subset of the Monte Carlo PDF replicas as an unbiased linear basis, and of a genetic algorithm for the determination of the optimal basis. We validate the methodology by first showing that it faithfully reproduces a native Monte Carlo PDF set (NNPDF3.0), and then, that if applied to Hessian PDF set (MMHT14) which was transformed into a Monte Carlo set, it gives back the starting PDFs with minimal information loss. We then show that, when applied to a large Monte Carlo PDF set obtained as combination of several underlying sets, the methodology leads to a Hessian representation in terms of a rather smaller set of parameters (CMC-H PDFs), thereby providing an alternative implementation of the recently suggested Meta-PDF idea and a Hessian version of the recently suggested PDF compression algorithm (CMC-PDFs). The mc2hessian conversion code is made publicly available togethe...

  3. An Unbiased Hessian Representation for Monte Carlo PDFs

    E-print Network

    Stefano Carrazza; Stefano Forte; Zahari Kassabov; Jose Ignacio Latorre; Juan Rojo

    2015-05-29

    We develop a methodology for the construction of a Hessian representation of Monte Carlo sets of parton distributions, based on the use of a subset of the Monte Carlo PDF replicas as an unbiased linear basis, and of a genetic algorithm for the determination of the optimal basis. We validate the methodology by first showing that it faithfully reproduces a native Monte Carlo PDF set (NNPDF3.0), and then, that if applied to Hessian PDF set (MMHT14) which was transformed into a Monte Carlo set, it gives back the starting PDFs with minimal information loss. We then show that, when applied to a large Monte Carlo PDF set obtained as combination of several underlying sets, the methodology leads to a Hessian representation in terms of a rather smaller set of parameters (CMC-H PDFs), thereby providing an alternative implementation of the recently suggested Meta-PDF idea and a Hessian version of the recently suggested PDF compression algorithm (CMC-PDFs). The mc2hessian conversion code is made publicly available together with (through LHAPDF6) a Hessian representations of the NNPDF3.0 set, and the CMC-H PDF set.

  4. Unbiased Approach for Virus Detection in Skin Lesions

    PubMed Central

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

    2013-01-01

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

  5. Depicting qudit quantum mechanics and mutually unbiased qudit theories

    E-print Network

    André Ranchin

    2014-12-30

    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.

  6. Galois Unitaries, Mutually Unbiased Bases, and MUB-balanced states

    E-print Network

    D. M. Appleby; Ingemar Bengtsson; Hoan Bui Dang

    2014-10-31

    A Galois unitary is a generalization of the notion of anti-unitary operators. They act only on those vectors in Hilbert space whose entries belong to some chosen number field. For Mutually Unbiased Bases the relevant number field is a cyclotomic field. By including Galois unitaries we are able to remove a mismatch between the finite projective group acting on the bases on the one hand, and the set of those permutations of the bases that can be implemented as transformations in Hilbert space on the other hand. In particular we show that there exist transformations that cycle through all the bases in every dimension which is an odd power of an odd prime. (For even primes unitary MUB-cyclers exist.) These transformations have eigenvectors, which are MUB-balanced states (i.e. rotationally symmetric states in the original terminology of Wootters and Sussman) if and only if d = 3 modulo 4. We conjecture that this construction yields all such states in odd prime power dimension.

  7. Unbiased reconstruction of a mammalian transcriptional network mediating the differential response to pathogens

    E-print Network

    Amit, Ido

    Models of mammalian regulatory networks controlling gene expression have been inferred from genomic data but have largely not been validated. We present an unbiased strategy to systematically perturb candidate regulators ...

  8. Experimental studies of unbiased gluon jets from e^+e^? annihilations using the jet boost algorithm

    E-print Network

    Wilson, Graham Wallace; Abbiendi, G.; Ainsley, C.; Å kesson, P. F.; Alexander, G.; Allison, J.; Amaral, P.; Anagnostou, G.; Anderson, K. J.; Arcelli, S.; Asai, S.; Axen, D.; Azuelos, G.; Bailey, I.; Barberio, E.

    2004-02-25

    We present the first experimental results based on the jet boost algorithm, a technique to select unbiased samples of gluon jets in e^+e^? annihilations, i.e. gluon jets free of biases introduced by event selection or jet ...

  9. Unbiased Characterization of Node Pairs Over Large Graphs Pinghui Wang, Noah's Ark lab, Huawei, Hong Kong

    E-print Network

    Massachusetts at Amherst, University of

    A Unbiased Characterization of Node Pairs Over Large Graphs Pinghui Wang, Noah's Ark lab, Huawei by the NSFC funding 60921003 and 863 Program 2012AA011003 of China. Author's addresses: Pinghui Wang, HUAWEI

  10. Minimum Variance Unbiased Estimation of Reliability for the Truncated Exponential Distribution

    Microsoft Academic Search

    Y. S. Sathe; S. D. Varde

    1969-01-01

    This note derives the unique minimum variance unbiased estimate (MVUE) of the reliability function associated with the one-parameter exponential distribution which is truncated from above at a known point using the method of integral transforms.

  11. Estimating unbiased phenological trends by adapting site-occupancy models.

    PubMed

    Roth, Tobias; Strebel, Nicolas; Amrhein, Valentin

    2014-08-01

    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

  12. Unbiased Average Age-Appropriate Atlases for Pediatric Studies

    PubMed Central

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

    2010-01-01

    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

  13. Quantitative and unbiased analysis of directional persistence in cell migration.

    PubMed

    Gorelik, Roman; Gautreau, Alexis

    2014-08-01

    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

  14. Atomic Spectra

    NSDL National Science Digital Library

    Nave, Carl R.

    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.

  15. Unbiased Nonlinear Filtering of Fast Spin Echo MRI Images A. Samsonov1

    E-print Network

    Utah, University of

    averaging with limited number of iterations separately. At the same time, the flow-stopping image gradientsUnbiased Nonlinear Filtering of Fast Spin Echo MRI Images A. Samsonov1 , C. Johnson1 1 Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, Utah, United States Introduction

  16. A Derivation of the Unbiased Standard Error of Estimate: The General Case.

    ERIC Educational Resources Information Center

    O'Brien, Francis J., Jr.

    This paper is part of a series of applied statistics monographs intended to provide supplementary reading for applied statistics students. In the present paper, derivations of the unbiased standard error of estimate for both the raw score and standard score linear models are presented. The derivations for raw score linear models are presented in…

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

    Microsoft Academic Search

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

    1967-01-01

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

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

    Microsoft Academic Search

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

    1971-01-01

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

  19. Bound and quasibound state calculations for biased\\/unbiased semiconductor quantum heterostructures

    Microsoft Academic Search

    Emmanuel Anemogiannis; Elias N. Glytsis; Thomas K. Gaylord

    1993-01-01

    A complex transcendental equation valid for a wide range of electron energies for semiconductor quantum heterostructures under unbiased or biased conditions is derived. Its complex roots have as real parts the structure eigenenergy levels, and their imaginary parts are directly related to the lifetime of the corresponding eigenenergies. A numerical method is presented that is capable of extracting all these

  20. A UNIFIED MEASURE OF UNCERTAINTY OF ESTIMATED BEST LINEAR UNBIASED PREDICTORS IN SMALL AREA ESTIMATION PROBLEMS

    Microsoft Academic Search

    G. S. Datta; P. Lahiri

    Abstract: We obtain a second order approximation to the mean,squared error (MSE), and its estimate, of the empirical or estimated best linear unbiased pre- dictor (EBLUP) of a mixed effect in a general mixed linear normal model. This covers many,important small area models in the literature. Unlike previous research in this area, we provide a unified theory of measuring uncertainty

  1. Studies of discrete-time unbiased FIR filters of polynomial state-space models

    Microsoft Academic Search

    Yuriy S. Shmaliy; Oscar Ibarra-Manzano

    2010-01-01

    We study an unbiased finite impulse response (FIR) filter in applications to discrete-time state space models with polynomial representation of the states. The unique l-degree polynomial FIR filter gain and the estimate variance are found for a general case. The noise power gain (NG) is derived for white Gaussian noises in the model and in the measurement. The filter does

  2. Best quadratic unbiased estimators for variance components in the balanced two-way classification model

    Microsoft Academic Search

    J. Kleffe

    1975-01-01

    In this paper the balanced two-way cross clossification model with random effects and without interactions is considered and it is proved-without assuming a specific distribution for the random effects-that the HENDERSON estimator is the uniformly best quadratic unbiased estimator.

  3. Obtaining the Best Linear Unbiased Estimator of Noisy Signals by Non-Gaussian Component Analysis

    Microsoft Academic Search

    M. Sugiyama; M. Kawanabe; G. Blanchard; V. Spokoiny; K.-R. Muller

    2006-01-01

    Obtaining the best linear unbiased estimator (BLUE) of noisy signals is a traditional but powerful approach to noise reduction. Explicitly computing BLUE usually requires the prior knowledge of the subspace to which the true signal belongs and the noise covariance matrix. However, such prior knowledge is often unavailable in reality, which prevents us from applying BLUE to real-world problems. In

  4. An Unbiased Survey of 500 Nearby Stars for Debris Disks: A JCMT Legacy Program

    Microsoft Academic Search

    Brenda C. Matthews; Jane S. Greaves; Wayne S. Holland; Mark C. Wyatt; Michael J. Barlow; Pierre Bastien; Chas. A. Beichman; Andrew Biggs; Harold M. Butner; William R. F. Dent; James Di Francesco; Carsten Dominik; Laura Fissel; Per Friberg; A. G. Gibb; Mark Halpern; R. J. Ivison; Ray Jayawardhana; Tim Jenness; Doug Johnstone; J. J. Kavelaars; Jonathon L. Marshall; Neil Phillips; Gerald Schieven; Ignas A. G. Snellen; Helen J. Walker; Derek Ward-Thompson; Bernd Weferling; Glenn J. White; Jeremy Yates; Ming Zhu; Alison Craigon

    2007-01-01

    We present the scientific motivation and observing plan for an upcoming detection survey for debris disks using the James Clerk Maxwell Telescope. The SCUBA-2 Unbiased Nearby Stars (SUNS) survey will observe 500 nearby main-sequence and subgiant stars (100 of each of the A, F, G, K, and M spectral classes) to the 850 mum extragalactic confusion limit to search for

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

    Microsoft Academic Search

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

    2010-01-01

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

  6. Rapid Golgi Analysis Method for Efficient and Unbiased Classification of Dendritic Spines

    E-print Network

    Eroglu, Cagla

    Rapid Golgi Analysis Method for Efficient and Unbiased Classification of Dendritic Spines W Institute for Brain Sciences, Durham, North Carolina, United States of America Abstract Dendritic spines are the primary recipients of excitatory synaptic input in the brain. Spine morphology provides important

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

    SciTech Connect

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

    2011-03-15

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

  8. Phase operators, temporally stable phase states, mutually unbiased bases and exactly solvable quantum systems

    E-print Network

    Paris-Sud XI, Université de

    stable phase states for some exactly solvable quantum systems. Various algebraic structures were usedPhase operators, temporally stable phase states, mutually unbiased bases and exactly solvable of the harmonic oscillator algebra) and discuss its finite- and infinite-dimensional repre- sentations according

  9. Sign-Sign Algorithm for Unbiased IIR Filtering in Impulsive Noise

    E-print Network

    So, Hing-Cheung

    the signs of the regressor term and error function are required in up- dating the resultant algorithmSign-Sign Algorithm for Unbiased IIR Filtering in Impulsive Noise H. C. So Department of Computer Filtering, Impulsive Noise Abstract : A new equation-error based sign-sign algorithm, which is derived from

  10. 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

  11. C NMR Spectra C NMR Spectra

    E-print Network

    Collum, David B.

    S16 1 H and 13 C NMR Spectra (see p S3) Me N-i-Pr #12;S17 1 H and 13 C NMR Spectra (see p S3) Me NBn #12;S18 1 H and 13 C NMR Spectra (see p S4) NBn #12;S19 1 H and 13 C NMR Spectra (see p S4) NBn Me Me Me #12;S20 1 H and 13 C NMR Spectra (see p S4) N-n-Bu Me Me Me #12;S21 1 H and 13 C NMR Spectra

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

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    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.

  13. Contextual classification of multispectral image data - An unbiased estimator for the context distribution

    NASA Technical Reports Server (NTRS)

    Tilton, J. C.; Swain, P. H.; Vardeman, S. B.

    1981-01-01

    Recent investigations have demonstrated the effectiveness of a contextual classifier that combines spatial and spectral information employing a general statistical approach. This statistical classification algorithm exploits the tendency of certain ground-cover classes to occur more frequently in some spatial contexts than in others. Indeed, a key input to this algorithm is a statistical characterization of the context: the context distribution. Here a discussion is given of an unbiased estimator of the context distribution 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 noncontextual classifications and from contextual classifications utilizing other context distribution estimation techniques.

  14. Best Unbiased Estimators for the Three-Point Correlators of the Cosmic Microwave Background Radiation

    E-print Network

    Alejandro Gangui; Jerome Martin

    2001-02-22

    Measuring the three-point correlators of the Cosmic Microwave Background (CMB) anisotropies could help to get a handle on the level of non-Gaussianity present in the observational datasets and therefore would strongly constrain models of the early Universe. However, typically, the expected non-Gaussian signal is very small. Therefore, one has to face the problem of extracting it from the noise, in particular from the `cosmic variance' noise. For this purpose, one has to construct the best unbiased estimators for the three-point correlators that are needed for concrete detections of non-Gaussian features. In this article, we study this problem for both the CMB third moment and the CMB angular bispectrum. We emphasize that the knowledge of the best estimator for the former does not permit one to infer the best estimator for the latter and vice versa. We present the corresponding best unbiased estimators in both cases and compute their corresponding cosmic variances.

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

    PubMed

    Waxman, D; Peck, J R

    2004-12-01

    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

  16. Structure of the sets of mutually unbiased bases with cyclic symmetry

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

  17. Energy-Constrained Decentralized Best-Linear-Unbiased Estimation via Partial Sensor Noise Variance Knowledge

    Microsoft Academic Search

    Jwo-Yuh Wu; Qian-Zhi Huang; Ta-Sung Lee

    2008-01-01

    This letter studies the energy-constrained MMSE decentralized estimation problem with the best-linear-unbiased-estimator fusion rule, under the assumptions that 1. Each sensor can only send a quantized version of its raw measurement to the fusion center (FC), and 2. Exact knowledge of the sensor noise variance is unknown at the FC but only an associated statistical description is available. The problem

  18. Unbiased minimum-variance input and state estimation for linear discrete-time systems

    Microsoft Academic Search

    Steven Gillijns; Bart De Moor

    2007-01-01

    This paper addresses the problem of simultaneously estimating the state and the input of a linear discrete-time system. A recursive filter, optimal in the minimum-variance unbiased sense, is developed where the estimation of the state and the input are interconnected. The input estimate is obtained from the innovation by least-squares estimation and the state estimation problem is transformed into a

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

    SciTech Connect

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

    2011-03-15

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

  20. Explaining the failure of the unbiased forward rate hypothesis using a time-varying risk premium

    Microsoft Academic Search

    Tarek Bishr

    1998-01-01

    This dissertation uses a time-varying risk premium to explain the failure of the unbiased forward rate hypothesis. In our opinion the risk premium drives a wedge between the forward rate and the expected future spot rate. We derive the risk premium from a small open economy continuous-time partial-equilibrium model. An exogenous mixed jump-diffusion exchange rate process is used in order

  1. Robust self-unbiased, quantum random number generator based on avalanche photodiodes

    E-print Network

    Fang-Xiang Wang; Chao Wang; Wei Chen; Shuang Wang; De-Yong He; Fu-Sheng Lv; Zhen-Qiang Yin; Hong-Wei Li; Guang-Can Guo; Zheng-Fu Han

    2015-05-12

    We propose and demonstrate a scheme to realize a high-efficiency truly quantum random number generator (RNG) at room temperature. With the effective time bin encoding method, the avalanche pulses of APD is converted into intrinsically self-unbiased random number bits that is robust to slow varying noise. Light source is not necessary in this scheme. Furthermore, the experiment result indicates that a high speed RNG chip based on the scheme is potentially available with integratable APD array.

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

    PubMed Central

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

    2014-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    Kohn, S. A.; Micha?owski, M. J.; Bourne, N.; Baes, M.; Fritz, J.; Cooray, A.; De Looze, I.; De Zotti, G.; Dannerbauer, H.; Dunne, L.; Dye, S.; Eales, S.; Furlanetto, C.; Gonzalez-Nuevo, J.; Ibar, E.; Ivison, R. J.; Maddox, S. J.; Scott, D.; Smith, D. J. B.; Smith, M. W. L.; Symeonidis, M.; Valiante, E.

    2015-04-01

    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 20 BeppoSAX and Swift GRB host galaxies (at an average redshift of z = 3.1) located in the Herschel Astrophysical Terahertz Large Area Survey, the Herschel Virgo Cluster Survey, the Herschel Fornax Cluster Survey, the Herschel Stripe 82 Survey and the Herschel Multi-tiered Extragalactic Survey, totalling 880 deg2, or ˜3 per cent 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 Herschel survey - therefore our sample can be considered completely unbiased. Using deep data at wavelengths of 100-500 ?m, we tentatively detected 1 out of 20 GRB hosts located in these fields. We constrain their dust masses and star formation rates (SFRs), and discuss these in the context of recent measurements of submillimetre galaxies and ultraluminous infrared galaxies. The average far-infrared flux of our sample gives an upper limit on SFR of <114 M? yr-1. The detection rate of GRB hosts is consistent with that predicted assuming that GRBs trace the cosmic SFR density in an unbiased way, i.e. that the fraction of GRB hosts with SFR > 500 M? yr-1 is consistent with the contribution of such luminous galaxies to the cosmic star formation density.

  4. Unbiased molecular analysis of T cell receptor expression using template-switch anchored RT-PCR.

    PubMed

    Quigley, Máire F; Almeida, Jorge R; Price, David A; Douek, Daniel C

    2011-08-01

    A detailed knowledge of the principles that guide clonal selection within the memory and effector T cell pools is essential to further our understanding of the factors that influence effective T cell-mediated immunity and has direct implications for the rational design of vaccines and immunotherapies. This unit provides methods for the unbiased quantification and characterization of all expressed T cell receptor (TCR) gene products within any defined T cell population. The approach is based on a template-switch anchored reverse transcription-polymerase chain reaction (RT-PCR) and is optimized for the analysis of antigen-specific T cells isolated directly ex vivo. PMID:21809317

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

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    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.

  6. Structure of the sets of mutually unbiased bases with cyclic symmetry

    E-print Network

    Ulrich Seyfarth; Luis L. Sanchez-Soto; Gerd Leuchs

    2014-04-11

    Mutually unbiased bases that can be cyclically generated by a single unitary operator are of special interest, since 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 $\\mathbb{F}_2$ 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.

  7. Unbiased constraints on the clumpiness of the Universe from standard candles

    NASA Astrophysics Data System (ADS)

    Li, Zhengxiang; Ding, Xuheng; Zhu, Zong-Hong

    2015-04-01

    We perform unbiased tests for the clumpiness of the Universe by confronting the Zel'dovich-Kantowski-Dyer-Roeder luminosity distance, which describes the effect of local inhomogeneities on the propagation of light with the observational one estimated from measurements of standard candles, i.e., type Ia supernovae (SNe Ia) and gamma-ray bursts (GRBs). Methodologically, we first determine the light-curve fitting parameters which account for distance estimation in SNe Ia observations and the luminosity/energy relations which are responsible for distance estimation of GRBs in the global fit to reconstruct the Hubble diagrams in the context of a clumpy Universe. Subsequently, these Hubble diagrams allow us to achieve unbiased constraints on the matter density parameter ?m , as well as the clumpiness parameter ? which quantifies the fraction of homogeneously distributed matter within a given light cone. At a 1 ? confidence level, the constraints are ?m=0.34 ±0.02 and ? =1.0 0-0.02+0.00 from the joint analysis. The results suggest that the Universe full of Friedman-Lemaître-Robertson-Walker fluid is favored by observations of standard candles with very high statistical significance. On the other hand, they may also indicate that the Zel'dovich-Kantowski-Dyer-Roeder approximation is a sufficiently accurate form to describe the effects of local homogeneity on the expanding Universe.

  8. Weighted skewness and kurtosis unbiased by sample size and Gaussian uncertainties

    NASA Astrophysics Data System (ADS)

    Rimoldini, Lorenzo

    2014-07-01

    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.

  9. An Unbiased Method for Clustering Bacterial Effectors Using Host Cellular Phenotypes

    PubMed Central

    Hodgson, David J.

    2014-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    Jones, Michael W.; Jaatinen, Esa

    2008-01-01

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

  11. Night Spectra Quest.

    ERIC Educational Resources Information Center

    Jacobs, Stephen

    1995-01-01

    Presents the Night Spectra Quest, a pocket-sized chart that identifies in color the spectra of all the common night lights and has an integrally mounted, holographic diffraction grating to look through. (JRH)

  12. An unbiased FIR filter for TIE model of a local clock in applications to GPS-based timekeeping.

    PubMed

    Shmaliy, Yuriy S

    2006-05-01

    An unbiased finite impulse response (FIR) filter is proposed to estimate the time-interval error (TIE) K-degree polynomial model of a local clock in global positioning system (GPS)-based timekeeping in the presence of noise that is not obligatory Gaussian. Generic coefficients for the unbiased FIRs are derived. The low-degree FIRs and noise power gains are given. An estimation algorithm is proposed and examined for the TIE measurements of a crystal clock in the presence of the uniformly distributed sawtooth noise induced by the multichannel GPS timing receiver. Based upon this algorithm, we show that the unbiased FIR estimates are consistent with the reference (rubidium) measurements and fit them better than the standard Kalman filter. PMID:16764441

  13. Statistical Properties of Maximum Likelihood Estimators of Power Law Spectra Information

    NASA Technical Reports Server (NTRS)

    Howell, L. W., Jr.

    2003-01-01

    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.

  14. A CURE for noisy magnetic resonance images: chi-square unbiased risk estimation.

    PubMed

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

    2012-08-01

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

  15. Phosphonic Acid Modification of GaInP2 Photocathodes Toward Unbiased Photoelectrochemical Water Splitting.

    PubMed

    MacLeod, Bradley A; Steirer, K Xerxes; Young, James L; Koldemir, Unsal; Sellinger, Alan; Turner, John A; Deutsch, Todd G; Olson, Dana C

    2015-06-01

    The p-type semiconductor GaInP2 has a nearly ideal bandgap (?1.83 eV) for hydrogen fuel generation by photoelectrochemical water splitting but is unable to drive this reaction because of misalignment of the semiconductor band edges with the water redox half reactions. Here, we show that attachment of an appropriate conjugated phosphonic acid to the GaInP2 electrode surface improves the band edge alignment, closer to the desired overlap with the water redox potentials. We demonstrate that this surface modification approach is able to adjust the energetic position of the band edges by as much as 0.8 eV, showing that it may be possible to engineer the energetics at the semiconductor/electrolyte interface to allow for unbiased water splitting with a single photoelectrode having a bandgap of less than 2 eV. PMID:25970795

  16. Autonomous navigation method based on unbiased minimum-variance estimation during Mars entry

    NASA Astrophysics Data System (ADS)

    Fu, Huimin; Yang, Yusong; Xiao, Qiang; Wu, Yunzhang; Zhang, Yongbo

    2015-03-01

    Accurate navigation systems are required for future pinpoint Mars landing missions. A radio ranging augmented inertial measurement unit (IMU) navigation system concept is considered for the guided atmospheric entry phase. The systematic errors associated to the radio ranging and inertial measurements, and the atmospheric mission uncertainties are considered to be unknown. This paper presents the extension of an unbiased minimum-variance (EUMV) filter of a radio beacon/IMU navigation system. In the presence of unknown dynamics inputs, the filter joins the system state and the unknown systematic error estimation of a stochastic nonlinear time-varying discrete system. 3-DOF simulation results show that the performances of the proposed navigation filter algorithm, 100 m estimated altitude error and 8 m/s estimated velocity error, fulfills the need of future pinpoint Mars landing missions.

  17. An unbiased estimator of peculiar velocity with Gaussian distributed errors for precision cosmology

    NASA Astrophysics Data System (ADS)

    Watkins, Richard; Feldman, Hume A.

    2015-06-01

    We introduce a new estimator of the peculiar velocity of a galaxy or group of galaxies from redshift and distance estimates. This estimator results in peculiar velocity estimates which are statistically unbiased and have Gaussian distributed errors, thus complying with the assumptions of analyses that rely on individual peculiar velocities. We apply this estimator to the SFI++ and the Cosmicflows-2 catalogues of galaxy distances and, since peculiar velocity estimates of distant galaxies are error dominated, examine their error distributions. The adoption of the new estimator significantly improves the accuracy and validity of studies of the large-scale peculiar velocity field that assume Gaussian distributed velocity errors and eliminates potential systematic biases, thus helping to bring peculiar velocity analysis into the era of precision cosmology. In addition, our method of examining the distribution of velocity errors should provide a useful check of the statistics of large peculiar velocity catalogues, particularly those that are compiled out of data from multiple sources.

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

    PubMed

    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

    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

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

    NASA Technical Reports Server (NTRS)

    Johnson, H. M.

    1985-01-01

    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.

  20. Bates and best quadratic unbiased estimators for parameters of the covariance matrix in a normal linear model

    Microsoft Academic Search

    J. Kleffe; R. Pincus

    1974-01-01

    Let y = X ? + ? be a linear model with ? normally distributed such that E? = 0, . Starting from prior distributions with respect to ? and ? the authors develope the conception of BAQUE (BAYEsian Quadratic Unbiased Estimator) for estimation of linear functions of the ?i. It is shown that BAQUE depends only on the first

  1. 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

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

    2014-11-01

    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

  2. Crack spectra analysis

    SciTech Connect

    Tiernan, M.

    1980-09-01

    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.

  3. Evaporation neutron spectra

    Microsoft Academic Search

    V. Sidorov

    1962-01-01

    The neutron spectra produced in the bombardment or V, Co, and Ni targets ; by alpha particles at 11 to 20 Mev are measured using the time-of-flight method. ; The analysis of these spectra according to the statistical theory of nuclear ; reactions is performed with an electronic computer. The level density fanction ; type that gives optimal agreement with

  4. Spectra of porphyrins

    Microsoft Academic Search

    Martin Gouterman

    1961-01-01

    The review opens by presenting the absorption spectra for three series of porphyrins derived from the basic skeleton: (a) compounds obtained by simple substitution; (b) compounds obtained by reduction of one or more pyrrole rings; and (c) compounds obtained from fusion of aromatic rings onto the basic skeleton. The spectra are discussed in terms of a four orbital model-that is

  5. Optical Spectra of Supernovae

    Microsoft Academic Search

    Alexei V. Filippenko

    1997-01-01

    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

  6. Biological spectra analysis: Linking biological activity profiles to molecular structure

    PubMed Central

    Fliri, Anton F.; Loging, William T.; Thadeio, Peter F.; Volkmann, Robert A.

    2005-01-01

    Establishing quantitative relationships between molecular structure and broad biological effects has been a longstanding challenge in science. Currently, no method exists for forecasting broad biological activity profiles of medicinal agents even within narrow boundaries of structurally similar molecules. Starting from the premise that biological activity results from the capacity of small organic molecules to modulate the activity of the proteome, we set out to investigate whether descriptor sets could be developed for measuring and quantifying this molecular property. Using a 1,567-compound database, we show that percent inhibition values, determined at single high drug concentration in a battery of in vitro assays representing a cross section of the proteome, provide precise molecular property descriptors that identify the structure of molecules. When broad biological activity of molecules is represented in spectra form, organic molecules can be sorted by quantifying differences between biological spectra. Unlike traditional structure–activity relationship methods, sorting of molecules by using biospectra comparisons does not require knowledge of a molecule's putative drug targets. To illustrate this finding, we selected as starting point the biological activity spectra of clotrimazole and tioconazole because their putative target, lanosterol demethylase (CYP51), was not included in the bioassay array. Spectra similarity obtained through profile similarity measurements and hierarchical clustering provided an unbiased means for establishing quantitative relationships between chemical structures and biological activity spectra. This methodology, which we have termed biological spectra analysis, provides the capability not only of sorting molecules on the basis of biospectra similarity but also of predicting simultaneous interactions of new molecules with multiple proteins. PMID:15625110

  7. An unbiased proteomics approach to identify human cytomegalovirus RNA-associated proteins.

    PubMed

    Lenarcic, Erik M; Ziehr, Benjamin J; Moorman, Nathaniel J

    2015-07-01

    Post-transcriptional events regulate herpesvirus gene expression, yet few herpesvirus RNA-binding proteins have been identified. We used an unbiased approach coupling oligo(dT) affinity capture with proteomics to identify viral RNA-associated proteins during infection. Using this approach, we identified and confirmed changes in the abundance or activity of two host RNA-associated proteins, DHX9 and DDX3, in cells infected with human cytomegalovirus (HCMV). We also identified and confirmed previously unreported activities for the HCMV US22 and pp71 proteins as RNA-associated viral proteins and confirmed that a known viral RNA-binding protein, pTRS1, associates with RNA in infected cells. Further, we found that HCMV pp71 co-sedimented with polysomes, associated with host and viral RNAs, and stimulated the overall rate of protein synthesis. These results demonstrate that oligo(dT) affinity capture coupled with proteomics provides a rapid and straightforward means to identify RNA-associated viral proteins during infection that may participate in the post-transcriptional control of gene expression. PMID:25765003

  8. P7C3 and an unbiased approach to drug discovery for neurodegenerative diseases

    PubMed Central

    McKnight, Steven L.; Ready, Joseph M.

    2014-01-01

    A novel neuroprotective small molecule was discovered using a target-agnostic in vivo screen in living mice. This aminopropyl carbazole, named P7C3, is orally bioavailable, crosses the blood–brain barrier, and is non-toxic at doses several fold higher than the efficacious dose. The potency and drug-like properties of P7C3 were optimized through a medicinal chemistry campaign, providing analogues for detailed examination. Improved versions, such as (?)-P7C3-S243 and P7C3-A20, displayed neuro-protective properties in rodent models of Parkinson’s disease, amyotrophic lateral sclerosis, traumatic brain injury and age-related cognitive decline. Derivatives appended with immobilizing moieties may reveal the protein targets of the P7C3 class of neuroprotective compounds. Our results indicate that unbiased, in vivo screens might provide starting points for the development of treatments for neurodegenerative diseases as well as tools to study the biology underlying these disorders. PMID:24514864

  9. An unbiased risk estimator for image denoising in the presence of mixed poisson-gaussian noise.

    PubMed

    Le Montagner, Yoann; Angelini, Elsa D; Olivo-Marin, Jean-Christophe

    2014-03-01

    The behavior and performance of denoising algorithms are governed by one or several parameters, whose optimal settings depend on the content of the processed image and the characteristics of the noise, and are generally designed to minimize the mean squared error (MSE) between the denoised image returned by the algorithm and a virtual ground truth. In this paper, we introduce a new Poisson-Gaussian unbiased risk estimator (PG-URE) of the MSE applicable to a mixed Poisson-Gaussian noise model that unifies the widely used Gaussian and Poisson noise models in fluorescence bioimaging applications. We propose a stochastic methodology to evaluate this estimator in the case when little is known about the internal machinery of the considered denoising algorithm, and we analyze both theoretically and empirically the characteristics of the PG-URE estimator. Finally, we evaluate the PG-URE-driven parametrization for three standard denoising algorithms, with and without variance stabilizing transforms, and different characteristics of the Poisson-Gaussian noise mixture. PMID:24723526

  10. Characterization of high-dimensional entangled systems via mutually unbiased measurements

    E-print Network

    D. Giovannini; J. Romero; J. Leach; A. Dudley; A. Forbes; M. J. Padgett

    2013-04-02

    Mutually unbiased bases (MUBs) play a key role in many protocols in quantum science, such as quantum key distribution. However, defining MUBs for arbitrary high-dimensional systems is theoretically difficult, and measurements in such bases can be hard to implement. We show experimentally that efficient quantum state reconstruction of a high-dimensional multi-partite quantum system can be performed by considering only the MUBs of the individual parts. The state spaces of the individual subsystems are always smaller than the state space of the composite system. Thus, the benefit of this method is that MUBs need to be defined for the small Hilbert spaces of the subsystems rather than for the large space of the overall system. This becomes especially relevant where the definition or measurement of MUBs for the overall system is challenging. We illustrate this approach by implementing measurements for a high-dimensional system consisting of two photons entangled in the orbital angular momentum (OAM) degree of freedom, and we reconstruct the state of this system for dimensions of the individual photons from d=2 to 5.

  11. Predicting hybrid performance in rice using genomic best linear unbiased prediction

    PubMed Central

    Xu, Shizhong; Zhu, Dan; Zhang, Qifa

    2014-01-01

    Genomic selection is an upgrading form of marker-assisted selection for quantitative traits, and it differs from the traditional marker-assisted selection in that markers in the entire genome are used to predict genetic values and the QTL detection step is skipped. Genomic selection holds the promise to be more efficient than the traditional marker-assisted selection for traits controlled by polygenes. Genomic selection for pure breed improvement is based on marker information and thus leads to cost-saving due to early selection before phenotypes are measured. When applied to hybrid breeding, genomic selection is anticipated to be even more efficient because genotypes of hybrids are predetermined by their inbred parents. Hybrid breeding has been an important tool to increase crop productivity. Here we proposed and applied an advanced method to predict hybrid performance, in which a subset of all potential hybrids is used as a training sample to predict trait values of all potential hybrids. The method is called genomic best linear unbiased prediction. The technology applied to hybrids is called genomic hybrid breeding. We used 278 randomly selected hybrids derived from 210 recombinant inbred lines of rice as a training sample and predicted all 21,945 potential hybrids. The average yield of top 100 selection shows a 16% increase compared with the average yield of all potential hybrids. The new strategy of marker-guided prediction of hybrid yields serves as a proof of concept for a new technology that may potentially revolutionize hybrid breeding. PMID:25114224

  12. Unbiased feature selection in learning random forests for high-dimensional data.

    PubMed

    Nguyen, Thanh-Tung; Huang, Joshua Zhexue; Nguyen, Thuy Thi

    2015-01-01

    Random forests (RFs) have been widely used as a powerful classification method. However, with the randomization in both bagging samples and feature selection, the trees in the forest tend to select uninformative features for node splitting. This makes RFs have poor accuracy when working with high-dimensional data. Besides that, RFs have bias in the feature selection process where multivalued features are favored. Aiming at debiasing feature selection in RFs, we propose a new RF algorithm, called xRF, to select good features in learning RFs for high-dimensional data. We first remove the uninformative features using p-value assessment, and the subset of unbiased features is then selected based on some statistical measures. This feature subset is then partitioned into two subsets. A feature weighting sampling technique is used to sample features from these two subsets for building trees. This approach enables one to generate more accurate trees, while allowing one to reduce dimensionality and the amount of data needed for learning RFs. An extensive set of experiments has been conducted on 47 high-dimensional real-world datasets including image datasets. The experimental results have shown that RFs with the proposed approach outperformed the existing random forests in increasing the accuracy and the AUC measures. PMID:25879059

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

    SciTech Connect

    Saro, Alex; Mohr, Joseph J.; Bazin, Gurvan; Dolag, Klaus [Department of Physics, Ludwig-Maximilians-Universitaet, Scheinerstr. 1, D-81679 Muenchen (Germany)

    2013-07-20

    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.

  14. H0 from an orientation-unbiased sample of SZ and X-ray clusters

    E-print Network

    Michael E. Jones; Alastair C. Edge; Keith Grainge; William F. Grainger; Ruediger Kneissl; G. G. Pooley; Richard Saunders; Shigeru J. Miyoshi; Taisuke Tsuruta; Koujun Yamashita; Yuzuru Tawara; Akihiro Furuzawa; Akihiro Harada; Isamu Hatsukade

    2001-03-02

    We have observed the Sunyaev-Zel'dovich effect in a sample of five moderate-redshift clusters with the Ryle Telescope, and used them in conjunction with X-ray imaging and spectral data from ROSAT and ASCA to measure the Hubble constant. This sample was chosen with a strict X-ray flux limit using both the BCS and NORAS cluster catalogues to be well above the surface-brightness limit of the ROSAT All-Sky Survey, and hence to be unbiased with respect to the orientation of the cluster. This controls the major potential systematic effect in the SZ/X-ray method of measureing H0. Taking the weighted geometric mean of the results and including the main sources of random error, namely the noise in the SZ measurement, the uncertainty in the X-ray temperatures and the unknown ellipticity of the clusters, we find H0 = 59 +8/-7 km/s/Mpc assuming a standard CDM model with Omega_M = 1.0, Omega_Lambda = 0.0, or H0 = 65 +8/-7 km/s/Mpc if Omega_M = 0.3, Omega_Lambda = 0.7.

  15. States that "look the same" with respect to every basis in a mutually unbiased set

    E-print Network

    Ilya Amburg; Roshan Sharma; Daniel Sussman; William K. Wootters

    2015-03-18

    A complete set of mutually unbiased bases in a Hilbert space of dimension $d$ defines a set of $d+1$ orthogonal measurements. Relative to such a set, we define a "MUB-balanced state" to be a pure state for which the list of probabilities of the $d$ outcomes of one of these measurements is independent of the choice of measurement, up to permutations. In this paper we explicitly construct a MUB-balanced state for each prime power dimension $d$ for which $d = 3$ (mod 4). These states have already been constructed by Appleby in unpublished notes, but our presentation here is different in that both the expression for the states themselves and the proof of MUB-balancedness are given in terms of the discrete Wigner function, rather than the density matrix or state vector. The discrete Wigner functions of these states are "rotationally symmetric" in a sense roughly analogous to the rotational symmetry of the energy eigenstates of a harmonic oscillator in the continuous two-dimensional phase space. Upon converting the Wigner function to a density matrix, we find that the states are expressible as real state vectors in the standard basis. We observe numerically that when $d$ is large (and not a power of 3), a histogram of the components of such a state vector appears to form a semicircular distribution.

  16. Realization of mutually unbiased bases for a qubit with only one wave plate: Theory and experiment

    E-print Network

    Zhibo Hou; Guoyong Xiang; Daoyi Dong; Chuan-Feng Li; Guang-Can Guo

    2015-03-01

    We consider the problem of implementing mutually unbiased bases (MUB) for a polarization qubit with only one wave plate, the minimum number of wave plates. We show that one wave plate is sufficient to realize two MUB as long as its phase shift (modulo $360^\\circ$) ranges between $45^\\circ$ and $315^\\circ$. {It can realize} three MUB (a complete set of MUB for a qubit) if the phase shift of the wave plate is within $[111.5^\\circ, 141.7^\\circ]$ or its symmetric range with respect to 180$^\\circ$. The systematic error of the realized MUB using a third-wave plate (TWP) with $120^\\circ$ phase is calculated to be a half of that using the combination of a quarter-wave plate (QWP) and a half-wave plate (HWP). As experimental applications, TWPs are used in single-qubit and two-qubit quantum state tomography experiments and the results show a systematic error reduction by $50\\%$. This technique not only saves one wave plate but also reduces the systematic error, which can be applied to quantum state tomography and other applications involving MUB. The proposed TWP may become a useful instrument in optical experiments, replacing multiple elements like QWP and HWP.

  17. Lily Pad Spectra

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The color image on the lower left from the panoramic camera on the Mars Exploration Rover Opportunity shows the 'Lily Pad' bounce-mark area at Meridiani Planum, Mars. This image was acquired on the 3rd sol, or martian day, of Opportunity's mission (Jan.26, 2004). The upper left image is a monochrome (single filter) image from the rover's panoramic camera, showing regions from which spectra were extracted from the 'Lily Pad' area. As noted by the line graph on the right, the green spectra is from the undisturbed surface and the red spectra is from the airbag bounce mark.

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

    Microsoft Academic Search

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

    2004-01-01

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

  19. An Unbiased Method To Build Benchmarking Sets for Ligand-Based Virtual Screening and its Application To GPCRs

    PubMed Central

    2015-01-01

    Benchmarking data sets have become common in recent years for the purpose of virtual screening, though the main focus had been placed on the structure-based virtual screening (SBVS) approaches. Due to the lack of crystal structures, there is great need for unbiased benchmarking sets to evaluate various ligand-based virtual screening (LBVS) methods for important drug targets such as G protein-coupled receptors (GPCRs). To date these ready-to-apply data sets for LBVS are fairly limited, and the direct usage of benchmarking sets designed for SBVS could bring the biases to the evaluation of LBVS. Herein, we propose an unbiased method to build benchmarking sets for LBVS and validate it on a multitude of GPCRs targets. To be more specific, our methods can (1) ensure chemical diversity of ligands, (2) maintain the physicochemical similarity between ligands and decoys, (3) make the decoys dissimilar in chemical topology to all ligands to avoid false negatives, and (4) maximize spatial random distribution of ligands and decoys. We evaluated the quality of our Unbiased Ligand Set (ULS) and Unbiased Decoy Set (UDS) using three common LBVS approaches, with Leave-One-Out (LOO) Cross-Validation (CV) and a metric of average AUC of the ROC curves. Our method has greatly reduced the “artificial enrichment” and “analogue bias” of a published GPCRs benchmarking set, i.e., GPCR Ligand Library (GLL)/GPCR Decoy Database (GDD). In addition, we addressed an important issue about the ratio of decoys per ligand and found that for a range of 30 to 100 it does not affect the quality of the benchmarking set, so we kept the original ratio of 39 from the GLL/GDD. PMID:24749745

  20. Thermodynamic analysis of spectra

    NASA Astrophysics Data System (ADS)

    Mitchell, G. E.; Shriner, J. F.

    2008-04-01

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

  1. Spectra of Grid Turbulence

    Microsoft Academic Search

    Mahinder S. Uberoi; Stanley Wallis

    1969-01-01

    Energy spectra of the longitudinal and lateral turbulent velocities are measured behind grids of different geometries; the isotropic relation is not satisfied. Energy-dissipating eddies are more nearly isotropic than energy-containing eddies. Spectra of the energy-containing eddies and their deviation from isotropy depend on the grid geometry. Various microscales are measured to determine the anisotropy of the energy-dissipating eddies. The error

  2. Nickel-Catalyzed Mizoroki-Heck Reaction of Aryl Sulfonates and Chlorides with Electronically Unbiased Terminal Olefins: High Selectivity for Branched Products

    E-print Network

    Tasker, Sarah Z.

    Achieving high selectivity in the Heck reaction of electronically unbiased alkenes has been a longstanding challenge. Using a nickel-catalyzed cationic Heck reaction, we were able to achieve excellent selectivity for ...

  3. [Fluorescence spectra and absorption spectra of carvacrol].

    PubMed

    Li, Li-Ran; Liu, Cui-Ge; Wei, Yong-Ju

    2011-10-01

    Fluorescence spectra and absorption spectra of carvacrol, an active component of Chinese herbal medicines, have been studied. The ionization constant and fluorescence quantum yield of carvacrol were measured according to spectral data. Under the condition of pH < 2.0, fluorescence intensity of carvacrol increases with the increase in pH value. In the range of pH 2.0-8.0, carvacrol gives a strong and steady fluorescence with maximum excitation wavelength 278 nm and emission wavelength 306 nm. When pH > 8.0, the fluorescence intensity decreases with the increase in pH value. Ionization constant of carvacrol was measured to be pK(a) = 10.44 +/- 0.06 using a pH-absorbance method; and pK(a) = 10.40 +/- 0.04 using a pH-fluorescence method. Fluorescence intensity of carvacrol was remarkably enhanced when methanol was added into its aqueous solution. Using L-tryptophane as a reference, the fluorescence quantum yield of carvacrol aqueous solution was measured to be 0.121 at excitation wavelength 278 nm; while in a solution containing 80% methanol, the quantum yield was measured to be 0.324. PMID:22250552

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

    PubMed

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

    2014-12-29

    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

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

    PubMed Central

    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

    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

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

    PubMed Central

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

    2015-01-01

    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

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

    PubMed Central

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

    2011-01-01

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

  8. Statistical Properties of Maximum Likelihood Estimators of Power Law Spectra Information

    NASA Technical Reports Server (NTRS)

    Howell, L. W.

    2002-01-01

    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.

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

    PubMed Central

    2014-01-01

    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

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

    PubMed Central

    Bahney, Jami; von Bartheld, Christopher S.

    2014-01-01

    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

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

    PubMed

    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

    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

  12. Enhanced methods for unbiased deep sequencing of Lassa and Ebola RNA viruses from clinical and biological samples.

    PubMed

    Matranga, Christian B; Andersen, Kristian G; Winnicki, Sarah; Busby, Michele; Gladden, Adrianne D; Tewhey, Ryan; Stremlau, Matthew; Berlin, Aaron; Gire, Stephen K; England, Eleina; Moses, Lina M; Mikkelsen, Tarjei S; Odia, Ikponmwonsa; Ehiane, Philomena E; Folarin, Onikepe; Goba, Augustine; Kahn, S Humarr; Grant, Donald S; Honko, Anna; Hensley, Lisa; Happi, Christian; Garry, Robert F; Malboeuf, Christine M; Birren, Bruce W; Gnirke, Andreas; Levin, Joshua Z; Sabeti, Pardis C

    2014-01-01

    We have developed a robust RNA sequencing method for generating complete de novo assemblies with intra-host variant calls of Lassa and Ebola virus genomes in clinical and biological samples. Our method uses targeted RNase H-based digestion to remove contaminating poly(rA) carrier and ribosomal RNA. This depletion step improves both the quality of data and quantity of informative reads in unbiased total RNA sequencing libraries. We have also developed a hybrid-selection protocol to further enrich the viral content of sequencing libraries. These protocols have enabled rapid deep sequencing of both Lassa and Ebola virus and are broadly applicable to other viral genomics studies. PMID:25403361

  13. Dual multifractal spectra.

    PubMed

    Roux, Stéphane; Jensen, Mogens H

    2004-01-01

    The multifractal formalism characterizes the scaling properties of a physical density rho as a function of the distance L. To each singularity alpha of the field is attributed a fractal dimension for its support f(alpha). An alternative representation has been proposed by considering the distribution of distances associated to a fixed mass. Computing these spectra for a multifractal Cantor set, it is shown that these two approaches are dual to each other, and that both spectra as well as the moment scaling exponents are simply related. We apply the same inversion formalism to exponents obtained for turbulent statistics in the Gledzer-Ohkitani-Yamada shell model and observe that the same duality relation holds here. PMID:14995714

  14. Mass spectra of copolymers.

    PubMed

    Montaudo, Maurizio S

    2002-01-01

    Recent and older literature (covering the last 12-13 years) in the field of mass spectra of random and block copolymers is reviewed. A detailed description is given of the information on copolymer properties that can be recovered from the analysis of the low-mass region of the spectrum (the region below 500 Da) and the high-mass region. The features of mass spectra of copolymers obtained by different synthetic routes are discussed, such as free radical, condensation, ring-chain equilibration, microbial synthesis, ring-opening, simple anionic, cationic, Ziegler-Natta, and/or metallocene catalysis, along with some random and block copolymers that occur in Nature. The emphasis is on copolymer composition and average molar mass determination, and on the benefits of coupling mass spectrometry (MS) with separation techniques such as size-exclusion chromatography (SEC) and high performance liquid chromatography (HPLC). PMID:12373747

  15. Leading neutron spectra

    E-print Network

    A. B. Kaidalov; V. A. Khoze; A. D. Martin; M. G. Ryskin

    2006-05-27

    It is shown that the observation of the spectra of leading neutrons from proton beams can be a good probe of absorptive and migration effects. We quantify how these effects modify the Reggeized pion-exchange description of the measurements of leading neutrons at HERA. We are able to obtain a satisfactory description of all the features of these data. We also briefly discuss the corresponding data for leading baryons produced in hadron-hadron collisions.

  16. An Unbiased 1.3 mm Emission Line Survey of the Protoplanetary Disk Orbiting LkCa 15

    NASA Astrophysics Data System (ADS)

    Punzi, K. M.; Hily-Blant, P.; Kastner, J. H.; Sacco, G. G.; Forveille, T.

    2015-06-01

    The outer (>30 AU) regions of the dusty circumstellar disk orbiting the ?2–5 Myr old, actively accreting solar analog LkCa 15 are known to be chemically rich, and the inner disk may host a young protoplanet within its central cavity. To obtain a complete census of the brightest molecular line emission emanating from the LkCa 15 disk over the 210–270 GHz (1.4–1.1 mm) range, we have conducted an unbiased radio spectroscopic survey with the Institute de Radioastronomie Millimétrique (IRAM) 30 m telescope. The survey demonstrates that in this spectral region, the most readily detectable lines are those of CO and its isotopologues 13CO and C18O, as well as HCO+, HCN, CN, C2H, CS, and H2CO. All of these species had been previously detected in the LkCa 15 disk; however, the present survey includes the first complete coverage of the CN (2–1) and C2H (3–2) hyperfine complexes. Modeling of these emission complexes indicates that the CN and C2H either reside in the coldest regions of the disk or are subthermally excited, and that their abundances are enhanced relative to molecular clouds and young stellar object environments. These results highlight the value of unbiased single-dish line surveys in guiding future high-resolution interferometric imaging of disks.

  17. Theoretical Studies of Molecular Spectra

    NASA Technical Reports Server (NTRS)

    McKay, Christopher (Technical Monitor); Freedman, Richard S.

    2002-01-01

    This summary describes the research activities of the principal investigator during the reporting period. The research includes spectroscopy, management of molecular databases, and generation of spectral line profiles and opacity data. The spectroscopy research includes oxygen broadening of nitric oxide (NO), analysis of CO2 spectra, analysis of HNO3 spectra, and analysis of CO spectra.

  18. Processing of Echellé spectra

    NASA Astrophysics Data System (ADS)

    Lyashko, D. A.; Tsymbal, V. V.; Makaganiuk, V. A.

    2007-10-01

    The current software was developed at the Taurida National University, astronomy department of physics faculty by Lyashko D.A., Tsymbal V.V. This programm comlex can be adapted according namely to individual spectrograph. All spectra processing goes automatically, so in this way it becomes possible to minimize user interaction with programm. It is very convinient and does not require special training for using it. In this case we can exclude human element and so then, output data corruption. The algotithm of processing due to differences between spectrographs is described in this paper.

  19. Einstein spectra of quasars

    NASA Technical Reports Server (NTRS)

    Wilkes, Belinda J.

    1988-01-01

    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.

  20. Continuum Fitting HST QSO Spectra

    NASA Technical Reports Server (NTRS)

    Tytler, David; Oliversen, Ronald J. (Technical Monitor)

    2002-01-01

    The Principal Component Analysis (PCA) method which we are using to fit and describe QSO spectra relies upon the fact that QSO continuum are generally very smooth and simple except for emission and absorption lines. To see this we need high signal-to-noise (S/N) spectra of QSOs at low redshift which have relatively few absorption lines in the Lyman-a forest. We need a large number of such spectra to use as the basis set for the PCA analysis which will find the set of principal component spectra which describe the QSO family as a whole. We have found that too few HST spectra have the required S/N and hence we need to supplement them with ground based spectra of QSOs at higher redshift. We have many such spectra and we have been working to make them suitable for this analysis. We have concentrated on this topic since 12/15/01.

  1. Preparing unbiased T-cell receptor and antibody cDNA libraries for the deep next generation sequencing profiling.

    PubMed

    Mamedov, Ilgar Z; Britanova, Olga V; Zvyagin, Ivan V; Turchaninova, Maria A; Bolotin, Dmitriy A; Putintseva, Ekaterina V; Lebedev, Yuriy B; Chudakov, Dmitriy M

    2013-01-01

    High-throughput sequencing has the power to reveal the nature of adaptive immunity as represented by the full complexity of T-cell receptor (TCR) and antibody (IG) repertoires, but is at present severely compromised by the quantitative bias, bottlenecks, and accumulated errors that inevitably occur in the course of library preparation and sequencing. Here we report an optimized protocol for the unbiased preparation of TCR and IG cDNA libraries for high-throughput sequencing, starting from thousands or millions of live cells in an investigated sample. Critical points to control are revealed, along with tips that allow researchers to minimize quantitative bias, accumulated errors, and cross-sample contamination at each stage, and to enhance the subsequent bioinformatic analysis. The protocol is simple, reliable, and can be performed in 1-2?days. PMID:24391640

  2. Preparing Unbiased T-Cell Receptor and Antibody cDNA Libraries for the Deep Next Generation Sequencing Profiling

    PubMed Central

    Mamedov, Ilgar Z.; Britanova, Olga V.; Zvyagin, Ivan V.; Turchaninova, Maria A.; Bolotin, Dmitriy A.; Putintseva, Ekaterina V.; Lebedev, Yuriy B.; Chudakov, Dmitriy M.

    2013-01-01

    High-throughput sequencing has the power to reveal the nature of adaptive immunity as represented by the full complexity of T-cell receptor (TCR) and antibody (IG) repertoires, but is at present severely compromised by the quantitative bias, bottlenecks, and accumulated errors that inevitably occur in the course of library preparation and sequencing. Here we report an optimized protocol for the unbiased preparation of TCR and IG cDNA libraries for high-throughput sequencing, starting from thousands or millions of live cells in an investigated sample. Critical points to control are revealed, along with tips that allow researchers to minimize quantitative bias, accumulated errors, and cross-sample contamination at each stage, and to enhance the subsequent bioinformatic analysis. The protocol is simple, reliable, and can be performed in 1–2?days. PMID:24391640

  3. WHFast: A fast and unbiased implementation of a symplectic Wisdom-Holman integrator for long term gravitational simulations

    E-print Network

    Rein, Hanno

    2015-01-01

    We present WHFast, a fast and accurate implementation of a Wisdom-Holman symplectic integrator for long-term orbit integrations of planetary systems. WHFast is significantly faster and conserves energy better than all other Wisdom-Holman integrators tested. We achieve this by significantly improving the Kepler-solver and ensuring numerical stability of coordinate transformations to and from Jacobi coordinates. These refinements allow us to remove the linear secular trend in the energy error that is present in other implementations. For small enough timesteps we achieve Brouwer's law, i.e. the energy error is dominated by an unbiased random walk due to floating-point round-off errors. We implement symplectic correctors up to order eleven that significantly reduce the energy error. We also implement a symplectic tangent map for the variational equations. This allows us to efficiently calculate two widely used chaos indicators the Lyapunov characteristic number (LCN) and the Mean Exponential Growth factor of Nea...

  4. Direct Metagenomic Detection of Viral Pathogens in Nasal and Fecal Specimens Using an Unbiased High-Throughput Sequencing Approach

    PubMed Central

    Sakon, Naomi; Ueda, Mayo; Tougan, Takahiro; Yamashita, Akifumi; Goto, Naohisa; Takahashi, Kazuo; Yasunaga, Teruo; Ikuta, Kazuyoshi; Mizutani, Tetsuya; Okamoto, Yoshiko; Tagami, Michihira; Morita, Ryoji; Maeda, Norihiro; Kawai, Jun; Hayashizaki, Yoshihide; Nagai, Yoshiyuki; Horii, Toshihiro; Iida, Tetsuya; Nakaya, Takaaki

    2009-01-01

    With the severe acute respiratory syndrome epidemic of 2003 and renewed attention on avian influenza viral pandemics, new surveillance systems are needed for the earlier detection of emerging infectious diseases. We applied a “next-generation” parallel sequencing platform for viral detection in nasopharyngeal and fecal samples collected during seasonal influenza virus (Flu) infections and norovirus outbreaks from 2005 to 2007 in Osaka, Japan. Random RT-PCR was performed to amplify RNA extracted from 0.1–0.25 ml of nasopharyngeal aspirates (N?=?3) and fecal specimens (N?=?5), and more than 10 µg of cDNA was synthesized. Unbiased high-throughput sequencing of these 8 samples yielded 15,298–32,335 (average 24,738) reads in a single 7.5 h run. In nasopharyngeal samples, although whole genome analysis was not available because the majority (>90%) of reads were host genome–derived, 20–460 Flu-reads were detected, which was sufficient for subtype identification. In fecal samples, bacteria and host cells were removed by centrifugation, resulting in gain of 484–15,260 reads of norovirus sequence (78–98% of the whole genome was covered), except for one specimen that was under-detectable by RT-PCR. These results suggest that our unbiased high-throughput sequencing approach is useful for directly detecting pathogenic viruses without advance genetic information. Although its cost and technological availability make it unlikely that this system will very soon be the diagnostic standard worldwide, this system could be useful for the earlier discovery of novel emerging viruses and bioterrorism, which are difficult to detect with conventional procedures. PMID:19156205

  5. Direct metagenomic detection of viral pathogens in nasal and fecal specimens using an unbiased high-throughput sequencing approach.

    PubMed

    Nakamura, Shota; Yang, Cheng-Song; Sakon, Naomi; Ueda, Mayo; Tougan, Takahiro; Yamashita, Akifumi; Goto, Naohisa; Takahashi, Kazuo; Yasunaga, Teruo; Ikuta, Kazuyoshi; Mizutani, Tetsuya; Okamoto, Yoshiko; Tagami, Michihira; Morita, Ryoji; Maeda, Norihiro; Kawai, Jun; Hayashizaki, Yoshihide; Nagai, Yoshiyuki; Horii, Toshihiro; Iida, Tetsuya; Nakaya, Takaaki

    2009-01-01

    With the severe acute respiratory syndrome epidemic of 2003 and renewed attention on avian influenza viral pandemics, new surveillance systems are needed for the earlier detection of emerging infectious diseases. We applied a "next-generation" parallel sequencing platform for viral detection in nasopharyngeal and fecal samples collected during seasonal influenza virus (Flu) infections and norovirus outbreaks from 2005 to 2007 in Osaka, Japan. Random RT-PCR was performed to amplify RNA extracted from 0.1-0.25 ml of nasopharyngeal aspirates (N = 3) and fecal specimens (N = 5), and more than 10 microg of cDNA was synthesized. Unbiased high-throughput sequencing of these 8 samples yielded 15,298-32,335 (average 24,738) reads in a single 7.5 h run. In nasopharyngeal samples, although whole genome analysis was not available because the majority (>90%) of reads were host genome-derived, 20-460 Flu-reads were detected, which was sufficient for subtype identification. In fecal samples, bacteria and host cells were removed by centrifugation, resulting in gain of 484-15,260 reads of norovirus sequence (78-98% of the whole genome was covered), except for one specimen that was under-detectable by RT-PCR. These results suggest that our unbiased high-throughput sequencing approach is useful for directly detecting pathogenic viruses without advance genetic information. Although its cost and technological availability make it unlikely that this system will very soon be the diagnostic standard worldwide, this system could be useful for the earlier discovery of novel emerging viruses and bioterrorism, which are difficult to detect with conventional procedures. PMID:19156205

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

    PubMed Central

    2014-01-01

    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

  7. TDS spectra analysis

    NASA Astrophysics Data System (ADS)

    Tomková, E.

    1996-05-01

    Methods of TDS spectra analysis start usually from the Polanyi-Wigner desorption rate equation. The Redhead approximative solution of the equation can be rearranged into a reduced form in which it serves as an analytical expression for the desorption rate versus time or temperature. Fitting the analytical form to an experimental curve we can confirm or deny the invariability of kinetic parameters — a desorption energy Ed and a preexponential factor ?l — and determine their values. If the parameters depend on surface coverage ? the application of the reduced form allows us to determine their values at ??0 and ?? ?0 and estimate the dependence Ed( ?), ?(?) from a single TDS spectrum. The method proposed in this paper is valid for the first-order kinetics of desorption; for the estimation mentioned above an assumption is made that desorption sites are identical and that E d as well as ?l changes with ? monotonously.

  8. 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

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

    1991-01-01

    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

  9. Unbiased species-level identification of clinical isolates of coagulase-negative Staphylococci: does it change the perspective on Staphylococcus lugdunensis?

    PubMed

    Elamin, Wael F; Ball, David; Millar, Michael

    2015-01-01

    Unbiased species-level identification of coagulase-negative staphylococci (CoNS) using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) identified Staphylococcus lugdunensis to be a more commonly isolated CoNS in our laboratory than previously observed. It has also highlighted the possibility of vertical transmission. PMID:25339392

  10. Vibrational spectra of 9-xanthone

    NASA Astrophysics Data System (ADS)

    Zwarich, R.; Binbrek, O. S.

    Polarized i.r. spectra of partially oriented 9-xanthone crystals grown from the melt between pressed salt plates and the i.r. spectra in a variety of solvents have been recorded from 180 to 3500 cm -1. The depolarization ratios of the Raman lines in the melt have been measured and the polarized Raman spectra of a crystal in all possible orientations have been recorded. The experimental assignment is compared with a set of calculated values.

  11. Interpreting Chromosome Aberration Spectra

    NASA Technical Reports Server (NTRS)

    Levy, Dan; Reeder, Christopher; Loucas, Bradford; Hlatky, Lynn; Chen, Allen; Cornforth, Michael; Sachs, Rainer

    2007-01-01

    Ionizing radiation can damage cells by breaking both strands of DNA in multiple locations, essentially cutting chromosomes into pieces. The cell has enzymatic mechanisms to repair such breaks; however, these mechanisms are imperfect and, in an exchange process, may produce a large-scale rearrangement of the genome, called a chromosome aberration. Chromosome aberrations are important in killing cells, during carcinogenesis, in characterizing repair/misrepair pathways, in retrospective radiation biodosimetry, and in a number of other ways. DNA staining techniques such as mFISH ( multicolor fluorescent in situ hybridization) provide a means for analyzing aberration spectra by examining observed final patterns. Unfortunately, an mFISH observed final pattern often does not uniquely determine the underlying exchange process. Further, resolution limitations in the painting protocol sometimes lead to apparently incomplete final patterns. We here describe an algorithm for systematically finding exchange processes consistent with any observed final pattern. This algorithm uses aberration multigraphs, a mathematical formalism that links the various aspects of aberration formation. By applying a measure to the space of consistent multigraphs, we will show how to generate model-specific distributions of aberration processes from mFISH experimental data. The approach is implemented by software freely available over the internet. As a sample application, we apply these algorithms to an aberration data set, obtaining a distribution of exchange cycle sizes, which serves to measure aberration complexity. Estimating complexity, in turn, helps indicate how damaging the aberrations are and may facilitate identification of radiation type in retrospective biodosimetry.

  12. Jets and QSO Spectra

    NASA Astrophysics Data System (ADS)

    Wills, B. J.; Brotherton, M. S.

    QSOs' emission lines arise from highest velocity (approximately 10000 km/s), dense gas within approximately 0.1 parsec of the central engine, out to low-velocity, low-density gas at great distances from the host galaxy. In radio-loud QSOs there are clear indications that the distribution and kinematics of emission-line gas are related to the symmetry axis of the central engine, as defined by the radio jet. These jets originate at nuclear distances < 0.1 pc --- similar to the highest-velocity emission line gas. There are two ways we can investigate the different environments of radio-loud and radio-quiet QSOs, i.e., those with and without powerful radio jets. One is to look for optical-UV spectroscopic differences between radio-loud and radio-quiet QSOs. The other is to investigate dependences of spectroscopic properties on properties of the powerful jets in radio-loud QSOs. Here we summarize the spectroscopic differences between the two classes, and present known dependences of spectra on radio core-dominance, which we interpret as dependences on the angle of the central engine to the line-of-sight. We speculate on what some of the differences may mean.

  13. IntrAst2 (Petrovay) Spectra STELLAR SPECTRA

    E-print Network

    Petrovay, Kristóf

    ) Spectra Kirchhoff's laws of spectroscopy (1860): 1. The spectrum of a hot body (solid body or opaque and spectrum of hydrogen (H I): Lyman series: ultraviolet domain Balmer series: optical domain Paschen series

  14. Abundance Calculations Using Synthetic Spectra

    NASA Astrophysics Data System (ADS)

    Pintado, O.; Adelman, S.

    2009-05-01

    Elemental abundance analysis are derived for the Mercury-Manganese star HR4817 (B8II/III), using CCD recorded exposures obtained with the EBASIM echelle spectrograph in the CASLEO (Complejo Astronómico El Leoncito) 2.1 m telescope in Argentina. The spectra coverage is 390-900 nm. The abundances and microturbulence are calculated using synthetic spectra. The results are compared with previous analyses made with spectra taken using the REOSC echelle spectrograph at CASLEO. With this method we make better determinations of abundances and microturbulence, and identify new chemical elements.

  15. Velocity determination from velocity spectra

    E-print Network

    Yang, Sung Jin

    1973-01-01

    . correction values, ms Sp no. correction values, ms 1 2 3 4 5 6 7 8 9 10 ll 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 source 30 30 32 27 27 27 33 33 32 29 25 25 29 27 25 25 25 26 31 40 23 23... Figure 14. CDP gathers at some shot points. . . Figure 15. Velocity spectra at SP 12. 5 and 20. 5. . 30 Figure 16. Velocity spectra at SP 28. 5 and 39. . 31 Figure 17. Velocity spectra at SP 43 and 52. . Figure 18. Stacked section. 37 Figure 19...

  16. Raman spectra of inorganic ions

    NASA Astrophysics Data System (ADS)

    Degen, I. A.; Newman, G. A.

    1993-06-01

    This paper contains the Raman spectra of 79 inorganic salts and sulphur which may be used as an aid in qualitative inorganic analyses. These were obtained some years ago by conventional Raman spectroscopy. No such collection exists and the order of the reference spectra is identical to those in a collection of IR spectra. A table of characteristic frequencies for 17 polyatomic ions is given. These data have increased relevance following the emergence of FT-Raman as a rapid and efficient modern technique.

  17. An Unbiased 1.3 mm Emission Line Survey of the Protoplanetary Disk Orbiting LkCa 15

    E-print Network

    Punzi, Kristina M; Kastner, Joel H; Sacco, G G; Forveille, Thierry

    2015-01-01

    The outer (>30 AU) regions of the dusty circumstellar disk orbiting the ~2-5 Myr-old, actively accreting solar analog LkCa 15 are known to be chemically rich, and the inner disk may host a young protoplanet within its central cavity. To obtain a complete census of the brightest molecular line emission emanating from the LkCa 15 disk over the 210-270 GHz (1.4 - 1.1 mm) range, we have conducted an unbiased radio spectroscopic survey with the Institute de Radioastronomie Millimetrique (IRAM) 30 meter telescope. The survey demonstrates that, in this spectral region, the most readily detectable lines are those of CO and its isotopologues 13CO and C18O, as well as HCO+, HCN, CN, C2H, CS, and H2CO. All of these species had been previously detected in the LkCa 15 disk; however, the present survey includes the first complete coverage of the CN (2-1) and C2H (3-2) hyperfine complexes. Modeling of these emission complexes indicates that the CN and C2H either reside in the coldest regions of the disk or are subthermally ...

  18. Measuring unbiased metatranscriptomics in suboxic waters of the central Baltic Sea using a new in situ fixation system.

    PubMed

    Feike, Janie; Jürgens, Klaus; Hollibaugh, James T; Krüger, Siegfried; Jost, Günter; Labrenz, Matthias

    2012-02-01

    An analysis of the microbial metabolism is fundamental to understanding globally important element transformations. One culture-independent approach to deduce those prokaryotic metabolic functions is to analyze metatranscriptomes. Unfortunately, since mRNA is extremely labile, it is unclear whether the abundance patterns detected in nature are vulnerable to considerable modification in situ simply due to sampling procedures. Exemplified on comparisons of metatranscriptomes retrieved from pelagic suboxic zones of the central Baltic Sea (70-120 m depth), earlier identified as areas of high aerobic ammonium oxidation activity, and quantification of specific transcripts in them, we show that different sampling techniques significantly influence the relative abundance of transcripts presumably diagnostic of the habitat. In situ fixation using our newly developed automatic flow injection sampler resulted in an abundance of thaumarchaeal ammonia monooxygenase transcripts that was up to 30-fold higher than that detected in samples obtained using standard oceanographic sampling systems. By contrast, the abundance of transcripts indicative of cellular stress was significantly greater in non-fixed samples. Thus, the importance of in situ fixation in the reliable evaluation of distinct microbial activities in the ecosystem based on metatranscriptomics is obvious. In consequence, our data indicate that the significance of thaumarchaeota to aerobic ammonium oxidation could yet have been considerably underestimated. Taken these results, this could in general also be the case in attempts aimed at an unbiased gene expression analysis of areas below the epipelagic zone, which cover 90% of the world's oceans. PMID:21776032

  19. Measuring unbiased metatranscriptomics in suboxic waters of the central Baltic Sea using a new in situ fixation system

    PubMed Central

    Feike, Janie; Jürgens, Klaus; Hollibaugh, James T; Krüger, Siegfried; Jost, Günter; Labrenz, Matthias

    2012-01-01

    An analysis of the microbial metabolism is fundamental to understanding globally important element transformations. One culture-independent approach to deduce those prokaryotic metabolic functions is to analyze metatranscriptomes. Unfortunately, since mRNA is extremely labile, it is unclear whether the abundance patterns detected in nature are vulnerable to considerable modification in situ simply due to sampling procedures. Exemplified on comparisons of metatranscriptomes retrieved from pelagic suboxic zones of the central Baltic Sea (70–120?m depth), earlier identified as areas of high aerobic ammonium oxidation activity, and quantification of specific transcripts in them, we show that different sampling techniques significantly influence the relative abundance of transcripts presumably diagnostic of the habitat. In situ fixation using our newly developed automatic flow injection sampler resulted in an abundance of thaumarchaeal ammonia monooxygenase transcripts that was up to 30-fold higher than that detected in samples obtained using standard oceanographic sampling systems. By contrast, the abundance of transcripts indicative of cellular stress was significantly greater in non-fixed samples. Thus, the importance of in situ fixation in the reliable evaluation of distinct microbial activities in the ecosystem based on metatranscriptomics is obvious. In consequence, our data indicate that the significance of thaumarchaeota to aerobic ammonium oxidation could yet have been considerably underestimated. Taken these results, this could in general also be the case in attempts aimed at an unbiased gene expression analysis of areas below the epipelagic zone, which cover 90% of the world's oceans. PMID:21776032

  20. Mutations that reduce aggregation of the Alzheimer's Abeta42 peptide: an unbiased search for the sequence determinants of Abeta amyloidogenesis.

    PubMed

    Wurth, Christine; Guimard, Nathalie K; Hecht, Michael H

    2002-06-21

    The primary component of amyloid plaque in the brains of Alzheimer's patients is the 42 residue amyloid-beta-peptide (Abeta42). Although the amino acid residue sequence of Abeta42 is known, the molecular determinants of Abeta amyloidogenesis have not been elucidated. To facilitate an unbiased search for the sequence determinants of Abeta aggregation, we developed a genetic screen that couples a readily observable phenotype in E. coli to the ability of a mutation in Abeta42 to reduce aggregation. The screen is based on our finding that fusions of the wild-type Abeta42 sequence to green fluorescent protein (GFP) form insoluble aggregates in which GFP is inactive. Cells expressing such fusions do not fluoresce. To isolate variants of Abeta42 with reduced tendencies to aggregate, we constructed and screened libraries of Abeta42-GFP fusions in which the sequence of Abeta42 was mutated randomly. Cells expressing GFP fusions to soluble (non-aggregating) variants of Abeta42 exhibit green fluorescence. Implementation of this screen enabled the isolation of 36 variants of Abeta42 with reduced tendencies to aggregate. The sequences of most of these variants are consistent with previous models implicating hydrophobic regions as determinants of Abeta42 aggregation. Some of the variants, however, contain amino acid substitutions not implicated in pre-existing models of Abeta amyloidogenesis. PMID:12079364

  1. WHFast: A fast and unbiased implementation of a symplectic Wisdom-Holman integrator for long term gravitational simulations

    E-print Network

    Hanno Rein; Daniel Tamayo

    2015-06-02

    We present WHFast, a fast and accurate implementation of a Wisdom-Holman symplectic integrator for long-term orbit integrations of planetary systems. WHFast is significantly faster and conserves energy better than all other Wisdom-Holman integrators tested. We achieve this by significantly improving the Kepler-solver and ensuring numerical stability of coordinate transformations to and from Jacobi coordinates. These refinements allow us to remove the linear secular trend in the energy error that is present in other implementations. For small enough timesteps we achieve Brouwer's law, i.e. the energy error is dominated by an unbiased random walk due to floating-point round-off errors. We implement symplectic correctors up to order eleven that significantly reduce the energy error. We also implement a symplectic tangent map for the variational equations. This allows us to efficiently calculate two widely used chaos indicators the Lyapunov characteristic number (LCN) and the Mean Exponential Growth factor of Nearby Orbits (MEGNO). WHFast is freely available as a flexible C package, as a shared library, and as an easy-to-use python module.

  2. Unbiased in vitro selection reveals the unique character of the self-cleaving antigenomic HDV RNA sequence

    PubMed Central

    Nehdi, Atef; Perreault, Jean-Pierre

    2006-01-01

    In order to revisit the architecture of the catalytic center of the antigenomic hepatitis delta virus (HDV) ribozyme we developed an unbiased in vitro selection procedure that efficiently selected novel variants from a relatively small set of sequences. Using this procedure we examined all possible variants from a pool of HDV ribozymes that had been randomized at 25 positions (425). The isolated set of sequences shows more variability than do the natural variants. Nucleotide variations were found at all randomized positions, even at positions when the general belief was that the specific base was absolutely required for catalytic activity. Covariation analysis supports the presence of several base pairs, although it failed to propose any new tertiary contacts. HDV ribozyme appears to possess a greater number of constraints, in terms of sequences capable of supporting the catalysed cleavage, than do other catalytic RNAs. This supports the idea that the appearance of this catalytic RNA structure has a low probability (i.e. is a rare event), which may explain why to date it has been found in nature only in the HDV. These contrasts with the hammerhead self-cleaving motif that is proposed to have multiple origins, and that is widespread among different organisms. Thus, just because a self-cleaving RNA motif is small does not imply that it occurs easily. PMID:16432262

  3. Nanoscale Synaptic Membrane Mimetic Allows Unbiased High Throughput Screen That Targets Binding Sites for Alzheimer’s-Associated A? Oligomers

    PubMed Central

    Wilcox, Kyle C.; Marunde, Matthew R.; Das, Aditi; Velasco, Pauline T.; Kuhns, Benjamin D.; Marty, Michael T.; Jiang, Haoming; Luan, Chi-Hao; Sligar, Stephen G.; Klein, William L.

    2015-01-01

    Despite their value as sources of therapeutic drug targets, membrane proteomes are largely inaccessible to high-throughput screening (HTS) tools designed for soluble proteins. An important example comprises the membrane proteins that bind amyloid ? oligomers (A?Os). A?Os are neurotoxic ligands thought to instigate the synapse damage that leads to Alzheimer’s dementia. At present, the identities of initial A?O binding sites are highly uncertain, largely because of extensive protein-protein interactions that occur following attachment of A?Os to surface membranes. Here, we show that A?O binding sites can be obtained in a state suitable for unbiased HTS by encapsulating the solubilized synaptic membrane proteome into nanoscale lipid bilayers (Nanodiscs). This method gives a soluble membrane protein library (SMPL)—a collection of individualized synaptic proteins in a soluble state. Proteins within SMPL Nanodiscs showed enzymatic and ligand binding activity consistent with conformational integrity. A?Os were found to bind SMPL Nanodiscs with high affinity and specificity, with binding dependent on intact synaptic membrane proteins, and selective for the higher molecular weight oligomers known to accumulate at synapses. Combining SMPL Nanodiscs with a mix-incubate-read chemiluminescence assay provided a solution-based HTS platform to discover antagonists of A?O binding. Screening a library of 2700 drug-like compounds and natural products yielded one compound that potently reduced A?O binding to SMPL Nanodiscs, synaptosomes, and synapses in nerve cell cultures. Although not a therapeutic candidate, this small molecule inhibitor of synaptic A?O binding will provide a useful experimental antagonist for future mechanistic studies of A?Os in Alzheimer’s model systems. Overall, results provide proof of concept for using SMPLs in high throughput screening for A?O binding antagonists, and illustrate in general how a SMPL Nanodisc system can facilitate drug discovery for membrane protein targets. PMID:25928376

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

    PubMed

    Vyas, Seema; Heise, Lori

    2014-11-01

    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

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

    PubMed Central

    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

    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

  6. The composite load spectra project

    NASA Technical Reports Server (NTRS)

    Newell, J. F.; Ho, H.; Kurth, R. E.

    1990-01-01

    Probabilistic methods and generic load models capable of simulating the load spectra that are induced in space propulsion system components are being developed. Four engine component types (the transfer ducts, the turbine blades, the liquid oxygen posts and the turbopump oxidizer discharge duct) were selected as representative hardware examples. The composite load spectra that simulate the probabilistic loads for these components are typically used as the input loads for a probabilistic structural analysis. The knowledge-based system approach used for the composite load spectra project provides an ideal environment for incremental development. The intelligent database paradigm employed in developing the expert system provides a smooth coupling between the numerical processing and the symbolic (information) processing. Large volumes of engine load information and engineering data are stored in database format and managed by a database management system. Numerical procedures for probabilistic load simulation and database management functions are controlled by rule modules. Rules were hard-wired as decision trees into rule modules to perform process control tasks. There are modules to retrieve load information and models. There are modules to select loads and models to carry out quick load calculations or make an input file for full duty-cycle time dependent load simulation. The composite load spectra load expert system implemented today is capable of performing intelligent rocket engine load spectra simulation. Further development of the expert system will provide tutorial capability for users to learn from it.

  7. Gallery of Planetary Nebula Spectra

    E-print Network

    Karen B. Kwitter; Richard B. C. Henry

    2006-05-03

    We present the Gallery of Planetary Nebula Spectra now available at http://oit.williams.edu/nebulae The website offers high-quality, moderate resolution (~7-10 A FWHM) spectra of 128 Galactic planetary nebulae from 3600-9600 A, obtained by Kwitter, Henry, and colleagues with the Goldcam spectrograph at the KPNO 2.1-m or with the RC spectrograph at the CTIO 1.5-m. The master PN table contains atlas data and an image link. A selected object's spectrum is displayed in a zoomable window; line identification templates are provided. In addition to the spectra themselves, the website also contains a brief discussion of PNe as astronomical objects and as contributors to our understanding of stellar evolution. We envision that this website, which concentrates a large amount of data in one place, will be of interest to a variety of users: researchers might need to check the spectrum of a particular object of interest; the non-specialist astronomer might simply be interested in perusing such a collection of spectra; and finally, teachers of introductory astronomy can use this database to illustrate basic principles of atomic physics and radiation. To particularly encourage this last use, we have developed two paper-and-pencil exercises to introduce beginning astronomy students to the wealth of information that PN spectra contain.

  8. Vibrational spectra of hexaaqua complexes

    Microsoft Academic Search

    Vladimir Ivanovski; Vladimir M. Petruševski; Bojan Šoptrajanov

    1999-01-01

    FT-IR spectra of RbAl(SO4)2·12H2O and KAl(SO4)2·12H2O alums were investigated in the region of the ?3(SO4) mode. The spectra were analyzed at room (?293K, RT) and at low temperature (?100K, LT). The doublet arising from this mode, evident in the LT spectrum, could be attributed to either site-group or correlation-field splitting. In order to reveal its exact origin, isomorphous isolation of

  9. Velocity determination from velocity spectra 

    E-print Network

    Yang, Sung Jin

    1973-01-01

    . on from Velocity Spectra (December 1973) Sung Jin Yang, B. S. Seoul National University; Korea Directed by: Dr. Anthony F. Gangi The reflected signals on the traces of a common-depth-point (CDP) gather appear along a hyperbolic curve which is a...VELOCITY DETERMINATION FRON VELOCITY SPECTRA A Thesis by SUNG JIN YANG Submutted to the Graduate C:lleEe of Texas ASM University in partial fulfill sent of requirement for the degree of EASTER GF SCIENCE December 1973 Naj or Subject...

  10. The SPECTRa Project: A Wider Chemistry View

    E-print Network

    Downing, Jim; Tonge, Alan

    2006-10-20

    (Controlled) public release User search tools OAI-PMH Metadata Harvesting Internet DSpace Escrow DSpace Open Computational Chemistry Calculations 2D Chemical Structures NMR Spectra 3D X-ray Structures SPECTRa Deposit Tools Create CML, InChI, metadata SPECTRa... Cotterill, Jim Downing Project Manager: Alan Tonge Library Liaison: Janet Evans, Lorraine Windsor http://www.lib.cam.ac.uk/spectra/ ...

  11. Unbiased Cluster Lens Reconstruction

    E-print Network

    Gordon Squires; Nick Kaiser

    1995-12-14

    Weak lensing observations measure the shear field and hence the gradient of the dimensionless surface density $\\kappa$. We present several new algorithms to recover $\\kappa$ {}from shear estimates on a finite region and compare how they perform with realistically noisy data. The reconstruction methods studied here are divided into 2 classes: direct reconstruction and regularized inversion. Direct reconstruction techniques express $\\kappa$ as a 2D integral of the shear field. This yields an estimator for $\\kappa$ as a discrete sum over background galaxy ellipticities which is straightforward to implement, and allows a simple estimate of the noise. We study 3 types of direct reconstruction methods: 1) $\\kappa$-estimators that measure the surface density at any given target point relative to the mean value in a reference region 2) a method that explicitly attempts to minimize the rotational part of $\

  12. Information Content of Iris Spectra

    Microsoft Academic Search

    John C. Price

    1975-01-01

    the number of independent variables needed to describe these broad band high spectral resolution data. The radiated power in the atmospheric window from 771 to 981 cm - was the first parameter chosen for, fitting observed spectra. At succeeding levels of analysis the residual variability (observed spectrum minus best-fit spectrum) in an ensemble of observations was partitioned into spectral eigenvectors.

  13. Metagenomic Analysis of Taxa Associated with Lutzomyia longipalpis, Vector of Visceral Leishmaniasis, Using an Unbiased High-Throughput Approach

    PubMed Central

    McCarthy, Christina B.; Diambra, Luis A.; Rivera Pomar, Rolando V.

    2011-01-01

    Background Leishmaniasis is one of the most diverse and complex of all vector-borne diseases worldwide. It is caused by parasites of the genus Leishmania, obligate intramacrophage protists characterised by diversity and complexity. Its most severe form is visceral leishmaniasis (VL), a systemic disease that is fatal if left untreated. In Latin America VL is caused by Leishmania infantum chagasi and transmitted by Lutzomyia longipalpis. This phlebotomine sandfly is only found in the New World, from Mexico to Argentina. In South America, migration and urbanisation have largely contributed to the increase of VL as a public health problem. Moreover, the first VL outbreak was recently reported in Argentina, which has already caused 7 deaths and 83 reported cases. Methodology/Principal Findings An inventory of the microbiota associated with insect vectors, especially of wild specimens, would aid in the development of novel strategies for controlling insect vectors. Given the recent VL outbreak in Argentina and the compelling need to develop appropriate control strategies, this study focused on wild male and female Lu. longipalpis from an Argentine endemic (Posadas, Misiones) and a Brazilian non-endemic (Lapinha Cave, Minas Gerais) VL location. Previous studies on wild and laboratory reared female Lu. longipalpis have described gut bacteria using standard bacteriological methods. In this study, total RNA was extracted from the insects and submitted to high-throughput pyrosequencing. The analysis revealed the presence of sequences from bacteria, fungi, protist parasites, plants and metazoans. Conclusions/Significance This is the first time an unbiased and comprehensive metagenomic approach has been used to survey taxa associated with an infectious disease vector. The identification of gregarines suggested they are a possible efficient control method under natural conditions. Ongoing studies are determining the significance of the associated taxa found in this study in a greater number of adult male and female Lu. longipalpis samples from endemic and non-endemic locations. A particular emphasis is being given to those species involved in the biological control of this vector and to the etiologic agents of animal and plant diseases. PMID:21909446

  14. Outline Phonon spectra of graphene Raman spectra of graphene Crystal lattice dynamics

    E-print Network

    of graphene Raman spectra of graphene Phonon branches of graphene 1 acoustic flexural mode ZA 2 ZA = Dzz 12(qOutline Phonon spectra of graphene Raman spectra of graphene Crystal lattice dynamics Graphene dynamics July 11, 2013 1 / 19 #12;Outline Phonon spectra of graphene Raman spectra of graphene 1 Phonon

  15. Hierarchical analysis of molecular spectra

    SciTech Connect

    Davis, M.J.

    1996-03-01

    A novel representation of molecular spectra in terms of hierarchical trees has proven to be an important aid for the study of many significant problems in gas-phase chemical dynamics. Trees are generated from molecular spectra by monitoring the changes that occur in a spectrum as resolution is changed in a continuous manner. A tree defines a genealogy among all lines of a spectrum. This allows for a detailed understanding of the assignment of features of a spectrum that may be difficult to obtain any other way as well as an understanding of intramolecular energy transfer time scales, mechanisms, and pathways. The methodology has been applied to several problems: transition state spectroscopy, intramolecular energy transfer in highly excited molecules, high-resolution overtone spectroscopy, and the nature of the classical-quantum correspondence when there is classical chaos (``quantum chaos``).

  16. Spectra of Modular Random Graphs

    Microsoft Academic Search

    Guler Ergun; R. Kuehn

    2009-01-01

    We compute spectra of symmetric random matrices defined on graphs exhibiting a modular structure. Modules are initially introduced as fully connected sub-units of a graph. By contrast, inter-module connectivity is taken to be incomplete. Two different types of inter-module connectivity are considered, one where the number of intermodule connections per-node diverges, and one where this number remains finite in the

  17. Wavelet spectra of JACEE events

    E-print Network

    Suzuki, N; Ohsawa, A; Suzuki, Naomichi; Biyajima, Minoru; Ohsawa, Akinori

    1995-01-01

    Pseudo-rapidity distributions of two high multiplicity events Ca-C and Si-AgBr observed by the JACEE are analysed by the wavelet transform. Wavelet spectra of those events are calculated and compared with the simulation calculations. The wavelet spectrum of Ca-C event somewhat resembles to that simulated with the uniform random numbers. That of Si-AgBr event is not reproduced by simulation calculations with Poisson random numbers, uniform random numbers, or a p-model.

  18. Diagram spaces and symmetric spectra

    Microsoft Academic Search

    Steffen Sagave; Christian Schlichtkrull

    2011-01-01

    We present a general homotopical analysis of structured diagram spaces and discuss the relation to symmetric spectra. The main motivating examples are the I-spaces, which are diagrams indexed by finite sets and injections, and J-spaces, which are diagrams indexed by the Grayson-Quillen construction on the category of finite sets and bijections. We show that the category of I-spaces provides a

  19. Modeling of skin reflectance spectra

    Microsoft Academic Search

    Igor V. Meglinsky; Stephen J. Matcher

    2001-01-01

    We use the optical\\/near-infrared (NIR) reflectance spectroscopy to non-invasively measure the hemoglobin saturation in living human skin. The difficulties in clinical application of this technique for skin tissue oxygenation monitoring are due to the complexity of extracting the information of chromophores distribution and their concentrations from the reflectance spectra in case of multiple scattering of light. We have developed a

  20. Optical Spectra of Triggered Lightning

    NASA Astrophysics Data System (ADS)

    Walker, T. D.; Biagi, C. J.; Hill, J. D.; Jordan, D. M.; Uman, M. A.; Christian, H. J., Jr.

    2009-12-01

    In August 2009, the first optical spectra of triggered lightning flashes were acquired. Data from two triggered lightning flashes were obtained at the International Center for Lightning Research and Testing in north-central Florida. The spectrometer that was used has an average dispersion of 260 Å/mm resulting in an average resolution of 5 Å when mated to a Photron (SA1.1) high-speed camera. The spectra captured with this system had a free spectral range of 3800-8000 Å. The spectra were captured at 300,000 frames per second. The spectrometer's vertical field of view was 3 m at an altitude 50 m above the launch tower, intended to view the middle of the triggering wire. Preliminary results show that the copper spectrum dominated the earliest part of the flash and copper lines persisted during the total lifetime of the detectable spectrum. Animations over the lifetime of the stroke from the initial wire illumination to multiple return strokes show the evolution of the spectrum. In addition, coordinated high speed channel base current, electric field and imagery measurements of the exploding wire, downward leaders, and return strokes were recorded. Quantitative analysis of the spectral evolution will be discussed in the context of the overall flash development.

  1. Learning and activity after irradiation of the young mouse brain analyzed in adulthood using unbiased monitoring in a home cage environment.

    PubMed

    Karlsson, Niklas; Kalm, Marie; Nilsson, Marie K L; Mallard, Carina; Björk-Eriksson, Thomas; Blomgren, Klas

    2011-03-01

    Cranial radiotherapy during the treatment of pediatric malignancies may cause adverse late effects. It is important to find methods to assess the functional effects of ionizing radiation in animal models and to evaluate the possible ameliorating effects of preventive or reparative treatment strategies. We investigated the long-term effects of a single 8-Gy radiation dose to the brains of 14-day-old mice. Activity and learning were evaluated in adulthood using open field and trace fear conditioning (TFC). These established methods were compared with the novel IntelliCage platform, which enables unbiased analysis of both activity and learning over time in a home cage environment. Neither activity nor learning was changed after irradiation, as judged by the open field and TFC analyses. The IntelliCage, however, revealed both altered activity and learning impairment after irradiation. Place learning and reversal learning were both impaired in the IntelliCage 3 months after irradiation. These results indicate that activity and learning should be assessed using multiple methods and that unbiased analysis over time in a home cage environment may offer advantages in the detection of subtle radiation-induced effects on the young brain. PMID:21388277

  2. Evaluation of Unbiased Next-Generation Sequencing of RNA (RNA-seq) as a Diagnostic Method in Influenza Virus-Positive Respiratory Samples.

    PubMed

    Fischer, Nicole; Indenbirken, Daniela; Meyer, Thomas; Lütgehetmann, Marc; Lellek, Heinrich; Spohn, Michael; Aepfelbacher, Martin; Alawi, Malik; Grundhoff, Adam

    2015-07-01

    Unbiased nontargeted metagenomic RNA sequencing (UMERS) has the advantage to detect known as well as unknown pathogens and, thus, can significantly improve the detection of viral, bacterial, parasitic, and fungal sequences in public health settings. In particular, conventional diagnostic methods successfully identify the putative pathogenic agent in only 30% to 40% of respiratory specimens from patients with acute respiratory illness. Here, we applied UMERS to 24 diagnostic respiratory specimens (bronchoalveolar lavage [BAL] fluid, sputum samples, and a swab) from patients with seasonal influenza infection and 5 BAL fluid samples from patients with pneumonia that tested negative for influenza to validate RNA sequencing as an unbiased diagnostic tool in comparison to conventional diagnostic methods. In addition to our comparison to PCR, we evaluated the potential to retrieve comprehensive influenza virus genomic information and the capability to detect known superinfecting pathogens. Compared to quantitative real-time PCR for influenza viral sequences, UMERS detected influenza viral sequences in 18 of 24 samples. Complete influenza virus genomes could be assembled from 8 samples. Furthermore, in 3 of 24 influenza-positive samples, additional viral pathogens could be detected, and 2 of 24 samples showed a significantly increased abundance of individual bacterial species known to cause superinfections during an influenza virus infection. Thus, analysis of respiratory samples from known or suspected influenza patients by UMERS provides valuable information that is relevant for clinical investigation. PMID:25972420

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

    PubMed

    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

    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

  4. Infrared Spectra of Polycyclic Aromatic Hydrocarbons (PAHs)

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Bakes, E. L. O.

    2000-01-01

    We have computed the synthetic infrared spectra of some polycyclic aromatic hydrocarbons containing up to 54 carbon atoms. The species studied include ovalene, circumcoronene, dicoronylene, and hexabenzocoronene. We report spectra for anions, neutrals, cations, and multiply charged cations.

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

    SciTech Connect

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

    2012-02-10

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

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

    SciTech Connect

    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

    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.

  7. Mass Spectra Alignments and their Significance

    E-print Network

    Lonardi, Stefano

    Mass Spectra Alignments and their Significance Sebastian B¨ocker1, Hans-Michael Kaltenbach2 1 Research, Universit¨at Bielefeld B¨ocker, Kaltenbach Mass Spectra Alignments CPM 2005 #12;Overview Mass¨ocker, Kaltenbach Mass Spectra Alignments CPM 2005 #12;Overview Mass Spectrometry in Proteomics Protein

  8. Satellite spectra of heliumlike nickel

    SciTech Connect

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

    1987-05-15

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

  9. Satellite spectra of heliumlike nickel

    SciTech Connect

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

    1987-02-01

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

  10. Mass spectra from field equations

    NASA Astrophysics Data System (ADS)

    Good, R. H., Jr.

    1994-07-01

    A type of field quantization is developed which, in some cases, leads directly from a field equation to a mass spectrum. The starting point is a field-Hamiltonian setup of the field equations. A Schrödinger-type wave function, a function of the field variables, is postulated and a Hamiltonian operator is inferred from the Hamiltonian function. A wave equation is suggested which has particle-type solutions only for special values of the rest mass. As examples, the spectra for the linear wave equation and for an equation with a sharply limited range of the field variable are discussed.

  11. C NMR Spectra (see p S10)

    E-print Network

    Collum, David B.

    S31 1 H and 13 C NMR Spectra (see p S10) NHBn Me Ph 10 #12;S32 1 H and 13 C NMR Spectra (see p S10) NHBn Me Ph 11 #12;S33 1 H and 13 C NMR Spectra (see p S11) NH-i-Pr n-Bu NH-i-Pr n-Bu 12 Me Me 13 #12;S34 1 H and 13 C NMR Spectra (see p S11)NH-i-Pr Me Ph 14 #12;S35 1 H and 13 C NMR Spectra (see p S11

  12. Hierarchical resolution of power spectra

    NASA Astrophysics Data System (ADS)

    Badii, R.; Finardi, M.; Broggi, G.; Sepúlveda, M. A.

    1992-09-01

    We identify the basic ingredients determining the structure of the power spectra of non-linear dynamical systems in a hierarchical order of importance. The analysis, performed with the help of symbolic methods, shows that dynamical invariants such as topological and metric properties of the symbolic orbits explain the main qualitative features of the spectra, whereas the coordinate-dependent values of the observable itself represent a less relevant contribution. Consideration of simple dynamical models with increasing number of topological transition rules evidences the formation of coherent structures (peaks) and explains their position and size. By constructing the parse tree of the allowed symbolic itineraries, it is possible to estimate conditional probabilities by considering orbits belonging to adjacent tree levels. Accordingly, a Markov transition matrix is obtained for each level l and is used to generate signals with statistical properties which approximate those of the actual one increasingly better for l ? ?. A considerable improvement is achieved by recoding the original signal in terms of variable-length words and by re-applying the above procedure to the transformed signal, which is equivalent to a renormalization operation of the associated dynamical map. The accuracy of the estimates is directly related to the convergence of the scaling function for the conditional probabilities. Analytic results are presented for the simplest five Markov models arising from piecewise-linear, continuous, one-dimensional maps. Numerical studies have been performed for the logistic and Hénon maps and for the Lorenz system.

  13. Locally induced and self-induced "electroclick" onto a self-assembled monolayer: writing and reading with SECM under unbiased conditions.

    PubMed

    Lhenry, Sébastien; Leroux, Yann R; Orain, Christophe; Conan, Francoise; Cosquer, Nathalie; Le Poul, Nicolas; Reinaud, Olivia; Le Mest, Yves; Hapiot, Philippe

    2014-04-22

    Localized "electroclick" was achieved on azido-terminated self-assembled monolayers using Scanning Electrochemical Microscopy (SECM) in feedback mode, in which the substrate is not electrically connected (unbiased conditions). The method allows both the local immobilization of diverse functional moieties and the monitoring of each modification step at a micrometer scale. Conditions of the "click" coupling reaction were optimized especially to avoid the deposit of metallic copper by the choice of a specific ligand to stabilize the Cu(I) species. The catalytic efficiency in localized "electroclick" reaction of Cu(II)TMPA (TMPA: tris(2-pyridylmethyl)amine) as the "click" catalyst was compared with a derivative containing an alkyne group Cu(II)6eTMPA, the same molecule playing the role of the catalyst and the substrate. Evidences for surface self-catalysis propagation are demonstrated through SECM imaging showing a random 2D progression of the catalytic modification. PMID:24673288

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

    PubMed Central

    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

    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

  15. Unbiased Proteomic Profiling Strategy for Discovery of Bacterial Effector Proteins Reveals that Salmonella Protein PheA Is a Host Cell Cycle Regulator.

    PubMed

    Na, Ha-Na; Yoo, Young-Hwa; Yoon, Chang No; Lee, Jun-Seok

    2015-04-23

    Salmonella utilizes a type III secretion system to inject bacterial effector proteins into the host cell cytosol. Once in the cytosol, these effectors hijack various biochemical pathways to regulate virulence. Despite the importance of effector proteins, especially for understanding host-pathogen interactions, a potentially large number of effectors are yet to be identified. Here, we demonstrate that unbiased chemical proteomic profiling using off-the-shelf fluorescent probes leads to the discovery of a host cell cycle regulator encoded in the Salmonella genome. Our profiling combined with bioinformatic analysis implicates 29 Salmonella as potential effectors. We follow up on the top candidate, chorismate mutase-P/prehenate dehydratase, PheA, and present evidence that PheA is an effector that mimics E2F7 transcription factor of the host cell and promotes G1/S cell cycle arrest. This validates our strategy and opens opportunities for effector identification in the future. PMID:25865312

  16. Reflectance spectra of primitive chondrites

    NASA Astrophysics Data System (ADS)

    Trigo-Rodríguez, J. M.; Moyano-Cambero, C. E.; Llorca, J.

    2013-05-01

    We are studying a wide sample of pristine carbonaceous chondrites from the NASA Antarctic collection in order to get clues on the physico-chemical processes occurred in the parent bodies of these meteorites. We are obtaining laboratory reflectance spectra of different groups of carbonaceous chondrites, but here we focus in CM and CI chondrites. We discuss the main spectral features that can be used to identify primitive carbonaceous asteroids by remote sensing techniques. Two different spectrometers were used covering the entire 0.3 to 30 ?m electromagnetic window. Only a handful of Near Earth Objects (NEOs) exhibit bands or features clearly associated with aqueous alteration. Among them are the target asteroids of Osiris Rex and Marco Polo-R missions.

  17. Ultraviolet stellar spectra obtained on Skylab

    NASA Technical Reports Server (NTRS)

    Henize, K. G.; Wray, J. D.; Parsons, S. B.; Benedict, G. F.

    1976-01-01

    A 15-cm aperture f/3 Ritchey-Chretien telescope equipped with a 4 deg calcium fluoride prism was employed in taking objective prism spectra from 1300 to 5000 A in 188 stars, in the three Skylab missions. Spectra of 2 A resolution at 1400 A and 10 A at 2000 A, extending to B0 stars such that V equals 6.5, were taken of 400 stars in the neighborhood of 1500 A. Stellar temperature and luminosity variations are revealed in resonance lines of C IV and Si IV. Profiles of P Cygni type show up in the spectra of all stars with absolute bolometric magnitudes brighter than minus 8.4, implying appreciable outflow of mass. Spectra with emission lines shortward of 2000 A were obtained for 12 WR stars, and spectra of some companion stars dominating the UV spectra are reported.

  18. Infrared spectra of natural and synthetic malachites

    NASA Astrophysics Data System (ADS)

    Schuiskii, A. V.; Zorina, M. L.

    2013-09-01

    IR absorption and reflection spectra of dark and light samples of natural and synthetic malachite over 400-4000 cm-1 are studied for the purpose of improving the synthesis technique and in order to distinguish between natural malachite and malachite grown from ammonia solutions. Nitrogen was not detected in the IR spectra or in microprobe analyses of the synthetic material. The differences found in the IR spectra were insignificant and cannot be regarded as distinctive indicators of these materials.

  19. Vibrational spectra and structure of dimethylaminodichlorophosphine.

    NASA Technical Reports Server (NTRS)

    Durig, J. R.; Casper, J. M.

    1971-01-01

    Evaluation of the infrared spectra of dimethylaminodichlorophosphine and dimethylaminodichlorophosphine-d sub 6 recorded from 4000 to 33 per cm in the gas and solid phases. The Raman spectra of the liquid and solid phases for both compounds were also recorded. The spectra were consistent with the presence of only one isomer over the range of phases and temperatures studied. Available experimental data were discussed in connection with the spectra, and it is concluded that the molecule exists in the gauche conformer with the PNC2 portion of the molecule planar. A vibrational assignment is proposed for the molecule.

  20. Infrared spectra of thyroid tumor tissues

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

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

  1. Mid-IR Properties of an Unbiased AGN Sample of the Local Universe. 1; Emission-Line Diagnostics

    NASA Technical Reports Server (NTRS)

    Weaver, K. A.; Melendez, M.; Muhotzky, R. F.; Kraemer, S.; Engle, K.; Malumuth. E.; Tueller, J.; Markwardt, C.; Berghea, C. T.; Dudik, R. P.; Winter, L. M.; Armus, L.

    2010-01-01

    \\Ve compare mid-IR emission-lines properties, from high-resolution Spitzer IRS spectra of a statistically-complete hard X-ray (14-195 keV) selected sample of nearby (z < 0.05) AGN detected by the Burst Alert Telescope (BAT) aboard Swift. The luminosity distribution for the mid-infrared emission-lines, [O IV] 25.89 microns, [Ne II] 12.81 microns, [Ne III] 15.56 microns and [Ne V] 14.32 microns, and hard X-ray continuum show no differences between Seyfert 1 and Seyfert 2 populations, although six newly discovered BAT AGNs are shown to be under-luminous in [O IV], most likely the result of dust extinction in the host galaxy. The overall tightness of the mid-infrared correlations and BAT luminosities suggests that the emission lines primarily arise in gas ionized by the AGN. We also compared the mid-IR emission-lines in the BAT AGNs with those from published studies of star-forming galaxies and LINERs. We found that the BAT AGN fall into a distinctive region when comparing the [Ne III]/[Ne II] and the [O IV]/[Ne III] quantities. From this we found that sources that have been previously classified in the mid-infrared/optical as AGN have smaller emission line ratios than those found for the BAT AGNs, suggesting that, in our X-ray selected sample, the AGN represents the main contribution to the observed line emission. Overall, we present a different set of emission line diagnostics to distinguish between AGN and star forming galaxies that can be used as a tool to find new AGN.

  2. Modelling asteroid spectra: few examples

    NASA Astrophysics Data System (ADS)

    Birlan, M.; Popescu, M.

    2011-10-01

    Asteroidal population comprises now more than 500,000 objects. Several observational techniques (spectroscopy, adaptive optics, photometry, polarimetry, radar,..) are used in order to obtain a mature understanding of an overall knowledge of this population. Spectroscopy can play a key role in determining the chemical composition and physical process that took place and modified the surface of asteroids. The development of telescopic instruments and the possibility to access them remotely allowed an increasing number of asteroid spectral measurements. The exploitation of spectral measurements is one of the important items to enlarge our science of surfaces of atmosphereless bodies. Spectral data of asteroids are in continuing growth. To exploit these spectral data we must account the global science of this population as well as the knowledge derived by studies of comparative planetology. The project M4AST (Modeling for Asteroids) consists in a database containing the results of these telescopic measurements and a set of applications for spectral analysis (Fig. 1). M4AST cover several aspects related to statistics of asteroids (taxonomy), mineralogical solutions using laboratory spectra from RELAB, and mineralogical modeling using space weathering effects corroborated with radiative transfer laws. M4AST was conceived to be available via a web interface and will be available for the scientific community. The abilities of these routines will be highlighted by few examples. Science derived via M4AST obtained for (222) Lucia, (809) Lundia, (810) Atossa, (1005) Arago, (1220) Crocus, and (4486) Mithra will be presented.

  3. Infrared spectra of protostellar collapse

    NASA Technical Reports Server (NTRS)

    Hollenbach, David J.; Ceccarelli, Cecilia; Neufeld, David A.; Tielens, Alexander G. G. M.

    1995-01-01

    Theoretical models of the formation of low mass stars by cloud collapse predict that OI(63 micrometers) and IR rotational lines of CO and H2O dominate the cooling in the freefalling region 10-1000 AU from the protostar. The freefalling gas supersonically hits the protoplanetary disk orbiting the protostar, forming an accretion shock with strong IR emission in rotational lines of H2O and OH, and OI(63 microns). The accretion shock spectra and line profiles depend on the mass flux through the shock and the typical distance r-bar at which the freefalling gas strikes the disk. The line widths are of order the Keplerian speed, or approx. 10(r-bar/10AU)(exp -0.5) km/s, for the accretion shock lines, and less for the lines from the infalling gas. Measurements of the IR line fluxes and profiles from the freefalling gas and the accretion shock diagnoses how a protostar and disk are formed and requires high sensitivity and high spectral and spatial resolving power. SOFIA will be the optimum observatory for many of these lines, although ISO will contribute and the KAO may make a few pioneering detections.

  4. lambda Bootis stars with composite spectra

    Microsoft Academic Search

    R. Faraggiana; P. Bonifacio; E. Caffau; M. Gerbaldi; M. Nonino

    2004-01-01

    We examine the large sample of lambda Boo candidates collected in Table 1 of Gerbaldi et al. (\\\\cite{Gerbaldi2003}) to see how many of them show composite spectra. Of the 132 lambda Boo candidates we identify 22 which definitely show composite spectra and 15 more for which there are good reasons to suspect a composite spectrum. The percentage of lambda Boo

  5. Spectra of Quarkonia at Finite Temperature

    E-print Network

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

    2006-06-02

    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.

  6. Effect of polarization on hadron inclusive spectra

    Microsoft Academic Search

    M. N. Kobrinskii; A. K. Likhoded

    1973-01-01

    The effect of polarization of initial particles on inclusive spectra is ; considered. It is shown that these spectra are independent of polarization in ; the framework of the quark theory. Possible variation of the proton spectrum due ; to the DELTA (1236)-resonance alignment is estimated. (auth);

  7. Composite complex Hadamard spectra of Boolean functions

    Microsoft Academic Search

    Bogdan J. Falkowski; Susanto Rahardja

    1996-01-01

    A new class of orthogonal transform, Complex Hadamard Transform is proposed as a spectral technique for analysis, synthesis and testing of Boolean functions. The method is presented to evaluate Complex Hadamard Spectra of AND, OR and XOR of Boolean functions directly front the spectra of the separate Boolean functions. The results are given using a general coding scheme, and different

  8. COMPUTER INTERPRETATION OF POLLUTANT MASS SPECTRA

    EPA Science Inventory

    The objective of this research was to improve systems for computer examination of the mass spectra of unknown pollutants. For this we have developed a new probability based matching (PBM) system for the retrieval of mass spectra from a large data base, and have substantially impr...

  9. Theoretical investigations of molecular triple ionization spectra

    Microsoft Academic Search

    G. Handke; F. Tarantelli; A. Sgamellotti; L. S. Cederbaum

    1996-01-01

    Triple ionization of molecular systems is investigated theoretically by means of the three-particle propagator. This enables us to efficiently calculate the very dense triple ionization spectra. To be able to interpret these spectra an atomic three-hole population analysis is developed which provides information about the charge distribution in the molecular trication. In exemplary applications on CO and a series of

  10. TANDEM: matching proteins with tandem mass spectra

    Microsoft Academic Search

    Robertson Craig; Ronald C. Beavis

    2004-01-01

    ABSTRACT Summary: Tandem mass spectra obtained from fragmenting peptide ions contain some peptide sequence specific information, but often there is not enough information to completely sequence the original peptide. Several proprietary software applications have been developed to attempt to match the spectra with a list of protein sequencesthat may contain the sequence of the peptide. The application TANDEM was writtento

  11. Mid-Infrared Spectra of Mercury

    NASA Technical Reports Server (NTRS)

    Cooper, B.; Potter, A. E.; Killen, R. M.; Morgan, T. H.

    2001-01-01

    Mid-infrared (8-13 microns) spectra of radiation emitted from the surface of solar system objects can be interpreted in terms of surface composition. However, the spectral features are weak, and require exceptionally high signal-to-noise ratio spectra to detect them. Ground-based observations of spectra in this region are plagued by strong atmospheric absorptions from water and ozone. High-altitude balloon measurements that avoid atmospheric absorptions can be affected by contamination of the optics by dust. We have developed a technique to obtain mid-infrared spectra of Mercury that minimizes these problems. The resulting spectra show evidence of transparency features that can be used to qualitatively characterize the surface composition. Additional information is contained in the original extended abstract.

  12. Thermal infrared spectra of the Moon

    NASA Technical Reports Server (NTRS)

    Salisbury, John W.; Murcray, D. G.; Williams, W. J.; Blatherwick, R. D.

    1995-01-01

    Contrary to recent assertions in the literature, lunar emission spectra obtained at an altitude of 32 km with a balloon-borne telescope are virtually undistorted by atmospheric absorption, except in the ozone region. These spectra have been found to correlate closely with laboratory emission spectra of returned lunar samples measured in a simulated lunar environment. Thus, lunar spectra obtained with the balloon-borne telescope system are the standards against which groundbased spectral measurements of the Moon should be compared. Comparison of balloon-borne measurements with recent groundbased spectral measurements suggests that the latter suffer from some source of systematic error. When high-quality lunar spectra are available, they will be best interpreted by comparison with returned lunar samples, rather than terrestrial minerals or rocks, because of subtle spectral differences between lunar and terrestrial minerals perhaps associated with incipient alteration of the latter.

  13. Modelling the Spectra of (BAL)QSOs

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

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

  14. Chiral allenes: theoretical VCD and IR spectra

    Microsoft Academic Search

    Joanna E Rode; Jan Cz Dobrowolski

    2003-01-01

    The theoretical geometries, rotational constants, VCD, and IR spectra for the chiral (S)-HXC?C?CFH (X=F, Cl, Br) allene molecules were calculated at the B3PW91\\/aug-cc-pVTZ level. We have shown that there is plausible adequacy between IR spectrum of (S)-1,3-difluoroallene molecule calculated at B3PW91\\/aug-cc-pVTZ level and experimental spectra of the racemate system. For the other molecules studied, the experimental spectra were not published,

  15. Unbiased Cell-based Screening in a Neuronal Cell Model of Batten Disease Highlights an Interaction between Ca2+ Homeostasis, Autophagy, and CLN3 Protein Function.

    PubMed

    Chandrachud, Uma; Walker, Mathew W; Simas, Alexandra M; Heetveld, Sasja; Petcherski, Anton; Klein, Madeleine; Oh, Hyejin; Wolf, Pavlina; Zhao, Wen-Ning; Norton, Stephanie; Haggarty, Stephen J; Lloyd-Evans, Emyr; Cotman, Susan L

    2015-06-01

    Abnormal accumulation of undigested macromolecules, often disease-specific, is a major feature of lysosomal and neurodegenerative disease and is frequently attributed to defective autophagy. The mechanistic underpinnings of the autophagy defects are the subject of intense research, which is aided by genetic disease models. To gain an improved understanding of the pathways regulating defective autophagy specifically in juvenile neuronal ceroid lipofuscinosis (JNCL or Batten disease), a neurodegenerative disease of childhood, we developed and piloted a GFP-microtubule-associated protein 1 light chain 3 (GFP-LC3) screening assay to identify, in an unbiased fashion, genotype-sensitive small molecule autophagy modifiers, employing a JNCL neuronal cell model bearing the most common disease mutation in CLN3. Thapsigargin, a sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA) Ca(2+) pump inhibitor, reproducibly displayed significantly more activity in the mouse JNCL cells, an effect that was also observed in human-induced pluripotent stem cell-derived JNCL neural progenitor cells. The mechanism of thapsigargin sensitivity was Ca(2+)-mediated, and autophagosome accumulation in JNCL cells could be reversed by Ca(2+) chelation. Interrogation of intracellular Ca(2+) handling highlighted alterations in endoplasmic reticulum, mitochondrial, and lysosomal Ca(2+) pools and in store-operated Ca(2+) uptake in JNCL cells. These results further support an important role for the CLN3 protein in intracellular Ca(2+) handling and in autophagic pathway flux and establish a powerful new platform for therapeutic screening. PMID:25878248

  16. 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

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

    2014-11-01

    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

  17. The Optically Unbiased Gamma-Ray Burst Host (TOUGH) Survey. VII. The Host Galaxy Luminosity Function: Probing the Relationship Between GRBs and Star Formation to Redshift $\\sim6$

    E-print Network

    Schulze, S; Hjorth, J; Levan, A J; Jakobsson, P; Björnsson, G; Perley, D A; Krühler, T; Gorosabel, J; Tanvir, N R; Postigo, A de Ugarte; Fynbo, J P U; Milvang-Jensen, B; Møller, P; Watson, D J

    2015-01-01

    Gamma-ray bursts (GRBs) offer a route to characterizing star-forming galaxies and quantifying high-$z$ star-formation that is distinct from the approach of traditional galaxy surveys: GRB selection is independent of dust and probes even the faintest galaxies that can evade detection in flux-limited surveys. However, the exact relation between GRB rate and Star Formation Rate (SFR) throughout all redshifts is controversial. The TOUGH survey includes observations of all GRB hosts (69) in an optically unbiased sample and we utilize these to constrain the evolution of the UV GRB-host-galaxy Luminosity Function (LF) between $z=0$ and $z=4.5$, and compare this with LFs derived from both Lyman-break galaxy (LBG) surveys and simulation modeling. At all redshifts we find the GRB hosts to be most consistent with a Luminosity Function derived from SFR weighted models incorporating GRB production via both metallicity-dependent and independent channels with a relatively high level of bias towards low metallicity hosts. In...

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

    PubMed Central

    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

    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

  19. ISOTOPIC ANALYSIS BY MEANS OF OPTICAL SPECTROSCOPY. II. MOLECULAR SPECTRA

    Microsoft Academic Search

    H. Tintea; C. Ungureanu; E. Weissmann

    1962-01-01

    Infrared spectra, rotation and infrared rotation-vibration spectra, ; Raman spectra, and other molecular spectra exhibit isotopic effects which may be ; used in isotopic assay. Diffraction gratings or prisms are used for the study of ; molecular spectra in the visible range, making use of photographic or ; photoelectric methods. High-frequency, electrode-free discharge tubes serve as ; light sources for

  20. Spatial evolution of ocean wave spectra

    NASA Technical Reports Server (NTRS)

    Beal, R. C.

    1981-01-01

    The spatially evolving deep water synthetic aperture radar (SAR) directional spectra of a mixed ocean wave system are compared with a comprehensive set of surface and aircraft measurements. The evolution of the SAR spectra, at least for ocean wavelengths greater than 80 m, is seen as generally consistent with the auxiliary data set in both time and space. From the spatial evolution of the angular component of the spectra, it is possible to project back to an apparent remote storm source that is also consistent with the storm location via GOES satellite imagery. The data provide compelling evidence that the spatial evolution of SAR ocean wave spectra can be a useful tool in global ocean wave monitoring and forecasting.

  1. The Polarizabilities of Ions from Spectra

    Microsoft Academic Search

    Joseph E. Mayer; Maria Goeppert Mayer

    1933-01-01

    The polarizabilities of the gaseous alkali ions, and several other ions of rare gas structure, have been calculated by the Born-Heisenberg method from the corresponding spectra. Correction has been made for the effect due to \\

  2. Theoretical spectra of terrestrial exoplanet surfaces

    E-print Network

    Hu, Renyu

    We investigate spectra of airless rocky exoplanets with a theoretical framework that self-consistently treats reflection and thermal emission. We find that a silicate surface on an exoplanet is spectroscopically detectable ...

  3. [Spectra of dark green jade from Myanmar].

    PubMed

    Mao, Jian; Chai, Lin-Tao; Guo, Shou-Guo; Fan, Jian-Liang; Bao, Feng

    2013-05-01

    Chemical compositions and spectral characteristics of one type of dark green jades assumed from omphacite jadeite from Myanmar jadeite mining area were studied by X-ray powder diffraction(XRD), X-ray fluorescence spectra(XRF), Raman spectra(RM) and UV-Vis Spectroscopy, etc. Based on testing by XRD and XRF, it was shown that it belongs to iron-enriched plagioclase, including albite and anorthite. The compositions range is between Ab0.731 An0.264 Or0.004 and Ab0.693 An0.303 Or0.004. Raman spectra of samples, albite jade and anorthite were collected and analyzed. Additionally, the distributions of Si, Al in the crystal structure were also discussed. UV-Vis spectra showed that dark green hue of this mineral is associated with d--d electronic transition of Fe3+ and Cr3+. PMID:23905358

  4. Numerical modelling of mineral impact ionisation spectra

    NASA Astrophysics Data System (ADS)

    Hillier, Jon K.; Fiege, K.; Trieloff, M.; Srama, R.

    2013-12-01

    We present model mass spectra of fayalite, forsterite, enstatite, ferrosilite, magnesiohornblende, ferrohornblende, anorthites, albite and Mg-Al spinel, as would be generated by a medium resolution impact ionisation cosmic dust mass spectrometer. Spectral peak intensities are found using ion relative sensitivity factors (RSFs) derived for TOF-SIMS mineral analysis. We demonstrate that, although TOF-SIMS RSFs are a reasonable approximation for the RSFs of impact ionisation, the RSFs for some important elements, such as Si, may differ by up to a factor of four. However, the TOF-SIMS RSFs are in general a valuable tool for predicting the peak intensities of inorganic species in impact ionisation mass spectra of minerals and mineral mixtures. The model spectra are used to estimate the ability of a medium resolution mass spectrometer to discriminate between different mineral compositions, and compared with impact ionisation mass spectra of anorthite cosmic dust analogue particles.

  5. Contribution to the study of turbulence spectra

    NASA Technical Reports Server (NTRS)

    Dumas, R.

    1979-01-01

    An apparatus suitable for turbulence measurement between ranges of 1 to 5000 cps and from 6 to 16,000 cps was developed and is described. Turbulence spectra downstream of the grills were examined with reference to their general characteristics, their LF qualities, and the effects of periodic turbulence. Medium and HF are discussed. Turbulence spectra in the boundary layers are similarly examined, with reference to their fluctuations at right angles to the wall, and to lateral fluctuations. Turbulence spectra in a boundary layer with suction to the wall is discussed. Induced turbulence, and turbulence spectra at high Reynolds numbers. Calculations are presented relating to the effect of filtering on the value of the correlations in time and space.

  6. Vibrational and vibronic spectra of tryptamine conformers.

    PubMed

    Mayorkas, Nitzan; Bernat, Amir; Izbitski, Shay; Bar, Ilana

    2013-03-28

    Conformation-specific ionization-detected stimulated Raman spectra, including both Raman loss and Raman gain lines, along with visible-visible-ultraviolet hole-burning spectra of tryptamine (TRA) conformers have been measured simultaneously, with the aim of obtaining new data for identifying them. The slightly different orientations of the ethylamine side chain relative to the indole lead to unique spectral signatures, pointing to the presence of seven TRA conformers in the molecular beam. Comparison of ionization-loss stimulated Raman spectra to computationally scaled harmonic Raman spectra, especially in the alkyl C-H and amine N-H stretch regions together with the retrieved information on the stabilities of the TRA conformers assisted their characterization and structural identification. The prospects and limitations of using these spectroscopic methods as potential conformational probes of flexible molecules are discussed. PMID:23556728

  7. Vibrational and vibronic spectra of tryptamine conformers

    NASA Astrophysics Data System (ADS)

    Mayorkas, Nitzan; Bernat, Amir; Izbitski, Shay; Bar, Ilana

    2013-03-01

    Conformation-specific ionization-detected stimulated Raman spectra, including both Raman loss and Raman gain lines, along with visible-visible-ultraviolet hole-burning spectra of tryptamine (TRA) conformers have been measured simultaneously, with the aim of obtaining new data for identifying them. The slightly different orientations of the ethylamine side chain relative to the indole lead to unique spectral signatures, pointing to the presence of seven TRA conformers in the molecular beam. Comparison of ionization-loss stimulated Raman spectra to computationally scaled harmonic Raman spectra, especially in the alkyl C-H and amine N-H stretch regions together with the retrieved information on the stabilities of the TRA conformers assisted their characterization and structural identification. The prospects and limitations of using these spectroscopic methods as potential conformational probes of flexible molecules are discussed.

  8. 2014 SPECTRA (Speedy Consolidation and Transition) Program

    E-print Network

    Kasman, Alex

    high school graduates who have been accepted to the College of Charleston for the fall semester from high school to the academic life of a college student. SPECTRA is very challenging, therefore only: _________________________________________________________ Name of High School: ___________________________________________________________ Graduation Date

  9. Area spectra of near extremal black holes

    E-print Network

    Deyou Chen; Haitang Yang; Xiaotao Zu

    2010-04-20

    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.

  10. New Dissimilarity Measures for Ultraviolet Spectra Identification

    Microsoft Academic Search

    Andrés Gutiérrez-Rodríguez; Miguel Angel Medina-Perez; José Martínez-Trinidad; Jesús Carrasco-Ochoa; Milton García-Borroto

    \\u000a Ultraviolet Spectra (UVS) analysis is a frequent tool in tasks like diseases diagnosis, drugs detection and hyperspectral\\u000a remote sensing. A key point in these applications is the UVS comparison function. Although there are several UVS comparisons\\u000a functions, creating good dissimilarity functions is still a challenge because there are different substances with very similar\\u000a spectra and the same substance may produce

  11. Photoneutron spectra around an 18 MV LINAC

    Microsoft Academic Search

    Hector Rene Vega-Carrillo; Antonio Baltazar-Raigosa

    2011-01-01

    Photoneutron spectra around an 18 MV LINAC were calculated in order to observe the effect produced by media around the accelerator.\\u000a Calculations were carried out with MCNP 4C code, three different cases were analyzed: Head model, Head and phantom model,\\u000a and Head, air, phantom and wall model. The spectra were calculated in five detectors located at the irradiation room at different

  12. Output spectra of the argon ion laser

    Microsoft Academic Search

    T. Bridges; W. Rigrod

    1965-01-01

    The output spectra of an A+ laser in its ? 4879.90 Å transition has been observed at various levels above threshold, in a ring resonator, a two-mirror resonator of the same longitudinal mode spacing (107 Mc\\/s), and another two-mirror resonator of about three times that mode spacing. Oscillations were restricted to the fundamental (Gaussian) mode. The A+ laser spectra display

  13. The Spitzer Atlas of Stellar Spectra (SASS)

    NASA Astrophysics Data System (ADS)

    Ardila, D. R.; van Dyk, S. D., Makowiecki, W.; Stauffer, J.; Song, I.; Ro, J.; Fajardo-Acosta, S.; Hoard, D. W.; Wachter, S.

    2011-11-01

    We present the Spitzer Atlas of Stellar Spectra (SASS), which includes 159 stellar spectra (5 to 32 micron; R about 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, like blue stragglers and certain pulsating variables. All the spectra have been uniformly reduced, and all are available online. For dwarfs and giants, the spectra of early-type objects are relatively featureless, dominated by Hydrogen lines around 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. The sample includes five M supergiant spectra, which show strong dust excesses and in some cases PAH 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.

  14. The Spitzer Atlas of Stellar Spectra (SASS)

    NASA Astrophysics Data System (ADS)

    Ardila, David R.; Van Dyk, Schuyler D.; Makowiecki, Wojciech; Stauffer, John; Song, Inseok; Rho, Jeonghee; Fajardo-Acosta, Sergio; Hoard, D. W.; Wachter, Stefanie

    2010-12-01

    We present the Spitzer Atlas of Stellar Spectra, which includes 159 stellar spectra (5-32 ?m R ~ 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.

  15. Diffuse emission and pathological Seyfert spectra

    NASA Technical Reports Server (NTRS)

    Halpern, Jules P.

    1995-01-01

    In this annual ROSAT status report, the diffuse emission and spectra from Seyfert galaxies are examined. Three papers are presented and their contents include the soft x-ray properties and spectra of a binary millisecond pulsar, the PSPC and HRI observations of a Starburst/Seyfert 2 Galaxy, and an analysis of the possibility of x-ray luminous starbursts in the Einstein Medium Sensitivity Survey.

  16. On the Photoelectron Spectra of Li4

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Arnold, James O. (Technical Monitor)

    1996-01-01

    The most stable structure for Li4(-) is found to be the rhombus. Electron detachment from this structure does not seem able to fully explain the photoelectron spectra. The computed results are consistent with those Rao, Jena, and Ray who have proposed that the experimental spectra consists of a superposition of detachment from the Li4(-) rhombus and tetrahedron, forming the singlet and triplet states of Li4, respectively.

  17. Impedance spectra of hydrating cement pastes

    Microsoft Academic Search

    C. A. Scuderi; T. O. Mason; H. M. Jennings

    1991-01-01

    Complex impedance spectra were obtained over the frequency range 5 Hz to 13 MHz on Portland cement pastes with water\\/cement ratios of 0.3, 0.35, and 0.4 at various hydration times from 6 h to 24 days. Features of the spectra which could be associated with the bulk material and which could be separated from the electrode arc, were studied. The

  18. Selection and Characterization of Interesting Grism Spectra

    E-print Network

    G. R. Meurer

    2006-01-02

    Observations with the ACS Wide Field Camera and G800L grism can produce thousands of spectra within a single WFC field producing a potentially rich treasure trove of information. However, the data are complicated to deal with. Here we describe algorithms to find and characterize spectra of emission line galaxies and supernovae using tools we have developed in conjunction with off the shelf software.

  19. Angular power spectra with finite counts

    NASA Astrophysics Data System (ADS)

    Campbell, Sheldon S.

    2015-04-01

    Angular anisotropy techniques for cosmic diffuse radiation maps are powerful probes, even for quite small data sets. A popular observable is the angular power spectrum; we present a detailed study applicable to any unbinned source skymap S(n) from which N random, independent events are observed. Its exact variance, which is due to the finite statistics, depends only on S(n) and N; we also derive an unbiased estimator of the variance from the data. First-order effects agree with previous analytic estimates. Importantly, heretofore unidentified higher order effects are found to contribute to the variance and may cause the uncertainty to be significantly larger than previous analytic estimates - potentially orders of magnitude larger. Neglect of these higher order terms, when significant, may result in a spurious detection of the power spectrum. On the other hand, this would indicate the presence of higher order spatial correlations, such as a large bispectrum, providing new clues about the sources. Numerical simulations are shown to support these conclusions. Applying the formalism to an ensemble of Gaussian-distributed skymaps, the noise-dominated part of the power-spectrum uncertainty is significantly increased at high multipoles by the new, higher order effects. This work is important for harmonic analyses of the distributions of diffuse high-energy ?-rays, neutrinos, and charged cosmic rays, as well as for populations of sparse point sources such as active galactic nuclei.

  20. Angular Power Spectra with Finite Counts

    E-print Network

    Sheldon S. Campbell

    2014-10-24

    Angular anisotropy techniques for cosmic diffuse radiation maps are powerful probes, even for quite small data sets. A popular observable is the angular power spectrum; we present a detailed study applicable to any unbinned source skymap S(n) from which N random, independent events are observed. Its exact variance, which is due to the finite statistics, depends only on S(n) and N; we also derive an unbiased estimator of the variance from the data. First-order effects agree with previous analytic estimates. Importantly, heretofore unidentified higher-order effects are found to contribute to the variance and may cause the uncertainty to be significantly larger than previous analytic estimates---potentially orders of magnitude larger. Neglect of these higher-order terms, when significant, may result in a spurious detection of the power spectrum. On the other hand, this would indicate the presence of higher-order spatial correlations, such as a large bispectrum, providing new clues about the sources. Numerical simulations are shown to support these conclusions. Applying the formalism to an ensemble of Gaussian-distributed skymaps, the noise-dominated part of the power spectrum uncertainty is significantly increased at high multipoles by the new, higher-order effects. This work is important for harmonic analyses of the distributions of diffuse high-energy gamma-rays, neutrinos, and charged cosmic rays, as well as for populations of sparse point sources such as active galactic nuclei.

  1. SIV genome-wide pyrosequencing provides a comprehensive and unbiased view of variation within and outside CD8 T lymphocyte epitopes.

    PubMed

    Hughes, Austin L; Becker, Ericka A; Lauck, Michael; Karl, Julie A; Braasch, Andrew T; O'Connor, David H; O'Connor, Shelby L

    2012-01-01

    Deep sequencing technology is revolutionizing our understanding of HIV/SIV evolution. It is known that acute SIV sequence variation within CD8 T lymphocyte (CD8-TL) epitopes is similar among MHC-identical animals, but we do not know whether this persists into the chronic phase. We now determine whether chronic viral variation in MHC-identical animals infected with clonal SIV is similar throughout the entire coding sequence when using a sensitive deep sequencing approach. We pyrosequenced the entire coding sequence of the SIV genome isolated from a unique cohort of four SIVmac239-infected, MHC-identical Mauritian cynomolgus macaques (MCM) 48 weeks after infection; one MCM in the cohort became an elite controller. Among the three non-controllers, we found that genome-wide sequences were similar between animals and we detected increased sequence complexity within 64% of CD8-TL epitopes when compared to Sanger sequencing methods. When we compared sequences between the MHC-matched controller and the three non-controllers, we found the viral population in the controller was less diverse and accumulated different variants than the viral populations in the non-controllers. Importantly, we found that initial PCR amplification of viral cDNA did not significantly affect the sequences detected, suggesting that data obtained by pyrosequencing PCR-amplified viral cDNA accurately represents the diversity of sequences replicating within an animal. This demonstrates that chronic sequence diversity across the entire SIV coding sequence is similar among MHC-identical animals with comparable viral loads when infected with the same clonal virus stock. Additionally, our approach to genome-wide SIV sequencing accurately reflects the diversity of sequences present in the replicating viral population. In sum, our study suggests that genome-wide pyrosequencing of immunodeficiency viruses captures a thorough and unbiased picture of sequence diversity, and may be a useful approach to employ when evaluating which sequences to include as part of a vaccine immunogen. PMID:23112852

  2. Identification and Biological Evaluation of a Novel and Potent Small Molecule Radiation Sensitizer via an Unbiased Screen of a Chemical Library

    PubMed Central

    Lally, Brian E.; Geiger, Geoffrey A.; Kridel, Steven; Arcury-Quandt, Alice E.; Robbins, Michael E.; Kock, Nancy D.; Wheeler, Kenneth; Peddi, Prakash; Georgakilas, Alexandros; Kao, Gary D.; Koumenis, Constantinos

    2013-01-01

    For patients with solid tumors, the tolerance of surrounding tissues often limits the dose of radiation that can be delivered. Thus, agents that preferentially increase the cytotoxic effects of radiation toward tumor cells would significantly alter the therapeutic ratio and improve patient survival. Using a high-throughput, unbiased screening approach, we have identified 4?-bromo-3?-nitropropiophenone (NS-123) as a radiosensitizer of human glioma cells in vitro and in vivo. NS-123 radiosensitized U251 glioma cells in a dose-dependent and time-dependent manner, with dose enhancement ratios ranging from 1.3 to 2.0. HT-29 colorectal carcinoma and A549 lung adenocarcinoma cells were also radiosensitized by NS-123 in vitro, whereas NS-123 did not increase the radiation sensitivity of normal human astrocytes or developmental abnormalities or lethality of irradiated Zebrafish embryos. In a novel xenograft model of U251 cells implanted into Zebrafish embryos, NS-123 enhanced the tumor growth-inhibitory effects of ionizing radiation (IR) with no apparent effect on embryo development. Similar results were obtained using a mouse tumor xenograft model in which NS-123 sensitized U251 tumors to IR while exhibiting no overt toxicity. In vitro pretreatment with NS-123 resulted in accumulation of unrepaired IR-induced DNA strand breaks and prolonged phosphorylation of the surrogate markers of DNA damage H2AX, ataxia telangiectasia mutated protein, DNA-dependent protein kinase, and CHK2 after IR, suggesting that NS-123 inhibits a critical step in the DNA repair pathway. These results show the potential of this cell-based, high-throughput screening method to identify novel radiosensitizers and suggest that NS-123 and similar nitrophenol compounds may be effective in antiglioma modalities. PMID:17875720

  3. 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

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

    2014-01-01

    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

  4. Cloud supersaturations from CCN spectra Hoppel minima

    NASA Astrophysics Data System (ADS)

    Hudson, James G.; Noble, Stephen; Tabor, Samantha

    2015-04-01

    High-resolution cloud condensation nucleus (CCN) spectral measurements in two aircraft field projects, Marine Stratus/Stratocumulus Experiment (MASE) and Ice in Clouds Experiment-Tropical (ICE-T), often showed bimodality that had previously been observed in submicrometer aerosol size distributions obtained by differential mobility analyzers. However, a great deal of spectral shape variability from very bimodal to very monomodal was observed in close proximity. Cloud supersaturation (S) estimates based on critical S, Sc, at minimal CCN concentrations between two modes (Hoppel minima) were ascertained for 63% of 325 measured spectra. These cloud S were lower than effective S (Seff) determined by comparing ambient CCN spectra with nearby cloud droplet concentrations (Nc). Averages for the polluted MASE stratus were 0.15 and 0.23% and for the cumulus clouds of ICE-T 0.44 and 1.03%. This cloud S disagreement between the two methods might in part be due to the fact that Hoppel minima include the effects of cloud processing, which push CCN spectra toward lower S. Furthermore, there is less cloud processing by the smaller cloud droplets, which might be related to smaller droplets evaporating more readily. Significantly lower concentrations within the more bimodal spectra compared with the monomodal spectra indicated active physical processes: Brownian capture of interstitial CCN and droplet coalescence. Chemical cloud processing also contributed to bimodality, especially in MASE.

  5. Background noise spectra of global seismic stations

    SciTech Connect

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

    1996-08-01

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

  6. EXPLORING THE MORPHOLOGY OF RAVE STELLAR SPECTRA

    SciTech Connect

    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

    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.

  7. Disk-averaged synthetic spectra of Mars

    NASA Technical Reports Server (NTRS)

    Tinetti, Giovanna; Meadows, Victoria S.; Crisp, David; Fong, William; Velusamy, Thangasamy; Snively, Heather

    2005-01-01

    The principal goal of the NASA Terrestrial Planet Finder (TPF) and European Space Agency's Darwin mission concepts is to directly detect and characterize extrasolar terrestrial (Earthsized) planets. This first generation of instruments is expected to provide disk-averaged spectra with modest spectral resolution and signal-to-noise. Here we use a spatially and spectrally resolved model of a Mars-like planet to study the detectability of a planet's surface and atmospheric properties from disk-averaged spectra. We explore the detectability as a function of spectral resolution and wavelength range, for both the proposed visible coronograph (TPFC) and mid-infrared interferometer (TPF-I/Darwin) architectures. At the core of our model is a spectrum-resolving (line-by-line) atmospheric/surface radiative transfer model. This model uses observational data as input to generate a database of spatially resolved synthetic spectra for a range of illumination conditions and viewing geometries. The model was validated against spectra recorded by the Mars Global Surveyor-Thermal Emission Spectrometer and the Mariner 9-Infrared Interferometer Spectrometer. Results presented here include disk-averaged synthetic spectra, light curves, and the spectral variability at visible and mid-infrared wavelengths for Mars as a function of viewing angle, illumination, and season. We also considered the differences in the spectral appearance of an increasingly ice-covered Mars, as a function of spectral resolution, signal-to-noise and integration time for both TPF-C and TPFI/ Darwin.

  8. Disk-averaged synthetic spectra of Mars.

    PubMed

    Tinetti, Giovanna; Meadows, Victoria S; Crisp, David; Fong, William; Velusamy, Thangasamy; Snively, Heather

    2005-08-01

    The principal goal of the NASA Terrestrial Planet Finder (TPF) and European Space Agency's Darwin mission concepts is to directly detect and characterize extrasolar terrestrial (Earthsized) planets. This first generation of instruments is expected to provide disk-averaged spectra with modest spectral resolution and signal-to-noise. Here we use a spatially and spectrally resolved model of a Mars-like planet to study the detectability of a planet's surface and atmospheric properties from disk-averaged spectra. We explore the detectability as a function of spectral resolution and wavelength range, for both the proposed visible coronograph (TPFC) and mid-infrared interferometer (TPF-I/Darwin) architectures. At the core of our model is a spectrum-resolving (line-by-line) atmospheric/surface radiative transfer model. This model uses observational data as input to generate a database of spatially resolved synthetic spectra for a range of illumination conditions and viewing geometries. The model was validated against spectra recorded by the Mars Global Surveyor-Thermal Emission Spectrometer and the Mariner 9-Infrared Interferometer Spectrometer. Results presented here include disk-averaged synthetic spectra, light curves, and the spectral variability at visible and mid-infrared wavelengths for Mars as a function of viewing angle, illumination, and season. We also considered the differences in the spectral appearance of an increasingly ice-covered Mars, as a function of spectral resolution, signal-to-noise and integration time for both TPF-C and TPFI/ Darwin. PMID:16078866

  9. Host galaxy spectra and consequences for supernova typing from the SDSS SN survey

    SciTech Connect

    Olmstead, Matthew D.; Brown, Peter J.; Brownstein, Joel R.; Dawson, Kyle S. [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Sako, Masao; Gupta, Ravi R. [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); Bassett, Bruce; Kunz, Martin [African Institute for Mathematical Sciences, 6 Melrose Road, Muizenberg, 7945 (South Africa); Bizyaev, Dmitry; Brinkmann, J.; Brewington, Howard; Ebelke, Garrett L. [Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349 (United States); Campbell, Heather [Institute of Astronomy, Madingley Road, Cambridge CB4 0HA (United Kingdom); D'Andrea, Chris B.; Lampeitl, Hubert [Institute of Cosmology and Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth, PO1 3FX (United Kingdom); Frieman, Joshua A. [Center for Particle Astrophysics, Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States); Galbany, Lluís [Institut de Física d'Altes Energies, Universitat Autònoma de Barcelona, E-08193 Bellaterra (Barcelona) (Spain); Garnavich, Peter [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Hlozek, Renee [Department of Astrophysics, Peyton Hall, 4 Ivy Lane, Princeton, NJ 08544 (United States); Jha, Saurabh W., E-mail: olmstead@physics.utah.edu [Department of Physics and Astronomy, Rutgers, the State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States); and others

    2014-04-01

    We present the spectroscopy from 5254 galaxies that hosted supernovae (SNe) or other transient events in the Sloan Digital Sky Survey II (SDSS-II). Obtained during SDSS-I, SDSS-II, and the Baryon Oscillation Spectroscopic Survey, this sample represents the largest systematic, unbiased, magnitude limited spectroscopic survey of SN host galaxies. Using the host galaxy redshifts, we test the impact of photometric SN classification based on SDSS imaging data with and without using spectroscopic redshifts of the host galaxies. Following our suggested scheme, there are a total of 1166 photometrically classified SNe Ia when using a flat redshift prior and 1126 SNe Ia when the host spectroscopic redshift is assumed. For 1024 (87.8%) candidates classified as likely SNe Ia without redshift information, we find that the classification is unchanged when adding the host galaxy redshift. Using photometry from SDSS imaging data and the host galaxy spectra, we also report host galaxy properties for use in future analysis of SN astrophysics. Finally, we investigate the differences in the interpretation of the light curve properties with and without knowledge of the redshift. Without host galaxy redshifts, we find that SALT2 light curve fits are systematically biased toward lower photometric redshift estimates and redder colors in the limit of low signal-to-noise data. The general improvements in performance of the light curve fitter and the increased diversity of the host galaxy sample highlights the importance of host galaxy spectroscopy for current photometric SN surveys such as the Dark Energy Survey and future surveys such as the Large Synoptic Survey Telescope.

  10. Raman and IR spectra of butane: Anharmonic calculations and interpretation of room temperature spectra

    E-print Network

    Potma, Eric Olaf

    Raman and IR spectra of butane: Anharmonic calculations and interpretation of room temperature-principles anharmonic calculations are carried out for the IR and Raman spectra of the CAH stretch- ing bands in butane.V. All rights reserved. 1. Introduction n-Butane is of great importance in several disciplines

  11. Interpretation of NMR Spectra. I. A2BXx and A2BKk Spectra

    Microsoft Academic Search

    Robert C. Hirst; David M. Grant; Edward G. Paul

    1966-01-01

    Difficulties encountered in analyzing NMR spectra are greatly multiplied as the number of interacting nuclei increases. The concept of effective internal chemical shifts or effective Larmor frequencies is developed here to simplify the study of complex NMR spectra in which a group of magnetically equivalent nuclei (Xx) is greatly shifted from a strongly coupled group. This concept permits decomposition of

  12. Mid-Infrared Spectra of Be Stars

    E-print Network

    S. A. Rinehart; J. R. Houck; J. D. Smith

    1999-10-11

    We present the first medium-resolution ($R\\sim 600$) mid-infrared (8-13.3\\micron) spectra of 11 Be stars. A large number of lines are observed and identified in these spectra, including, as an example, 39 hydrogen recombination lines in the spectrum of $\\gamma$ Cas. In the majority of our spectra, all of the observed lines are attributable to hydrogen recombination. Two of the sources, $\\beta$ Lyr and MWC 349 also show emission from other species. Both of these objects show evidence of [Ne II] emission, and $\\beta$ Lyr also shows evidence of He I emission. We tabulate the effective line strength and line widths for the observed lines, and briefly discuss the physical implications of the observed line series. We also use a simple model of free-free emission to characterize the disks around these sources.

  13. Quantitative analysis of NMR spectra with chemometrics

    NASA Astrophysics Data System (ADS)

    Winning, H.; Larsen, F. H.; Bro, R.; Engelsen, S. B.

    2008-01-01

    The number of applications of chemometrics to series of NMR spectra is rapidly increasing due to an emerging interest for quantitative NMR spectroscopy e.g. in the pharmaceutical and food industries. This paper gives an analysis of advantages and limitations of applying the two most common chemometric procedures, Principal Component Analysis (PCA) and Multivariate Curve Resolution (MCR), to a designed set of 231 simple alcohol mixture (propanol, butanol and pentanol) 1H 400 MHz spectra. The study clearly demonstrates that the major advantage of chemometrics is the visualisation of larger data structures which adds a new exploratory dimension to NMR research. While robustness and powerful data visualisation and exploration are the main qualities of the PCA method, the study demonstrates that the bilinear MCR method is an even more powerful method for resolving pure component NMR spectra from mixtures when certain conditions are met.

  14. Electronic spectra of asym-triazinyl groups

    SciTech Connect

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

    1987-08-01

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

  15. Ion and neutral scattering spectra in LEIS

    NASA Astrophysics Data System (ADS)

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

    2005-05-01

    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 1 keV, 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 discuss what one can learn from this comparison about elastic scattering (single scattering versus multiple scattering), about inelastic scattering (local versus non-local electronic energy loss) and about typical trajectories (validity of single scattering model, information depth). Our present understanding of ion and neutral scattering spectra in LEIS is discussed along these lines and results are presented for scattering of He + ions from polycrystalline Au.

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

    SciTech Connect

    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

    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.

  17. AIS-2 spectra of California wetland vegetation

    NASA Technical Reports Server (NTRS)

    Gross, Michael F.; Ustin, Susan L.; Klemas, Vytautas

    1987-01-01

    Spectral data gathered by Airborne Imaging Spectrometers-2 from wetlands were analyzed. Spectra representing stands of green Salicornia virginica, green Sesuvium verrucosum, senescing Distichlis spicata, a mixture of senescing Scirpus acutus and Scirpus californicus, senescing Scirpus paludosus, senescent S. paludosus, mowed senescent S. paludosus, and soil were isolated. No difference among narrowband spectral reflectance of the cover types was apparent between 0.8 to 1.6 micron. There were, however, broadband differences in brightness. These differences were sufficient to permit a fairly accurate decomposition of the image into its major cover type components using a procedure that assumes an additive linear mixture of surface spectra.

  18. Mid-infrared spectra of Martian komantiite

    NASA Technical Reports Server (NTRS)

    Reyes, David P.

    1992-01-01

    Synthetic mid-infrared emissive spectra of basalts of possible Martian komatiitic compositions were generated to show what might be seen in data returned from the Thermal Emission Spectrometer (TES). TES is flying on the Mars Observer arriving at Mars in late 1993. The synthetic Martian komatiite spectra were generated using mineralogy based on Shergottite, Nakhlite, and Chassigny (SNC) meteorites and Viking X-Ray Fluorescence (XRF) data. These data sets provide strong evidence for the existence of ultramafic lavas on Mars, particularly lavas of komatiitic composition.

  19. Vibrational spectra of phenylfluorone and their interpretation

    NASA Astrophysics Data System (ADS)

    Gladkova, O. L.; Panarin, A. Yu.; Terekhov, S. N.

    2011-05-01

    Fourier-transform IR absorption, Raman, and surface-enhanced Raman scattering spectra are presented for phenylfluorone, which is widely used as an analytical reagent in the photometric determination of high-valent metals from Groups III-VI of the Periodic Table. A geometric structure and vibrational frequencies for the phenylfluorone molecule were calculated using a quantum-mechanical density-functional method. An interpretation of its vibrational spectra was proposed for the first time. Spectral effects of phenylfluorone protonation have been studied. The geometry of phenylfluorone adsorbed on the surface of nanostructured silver films was examined.

  20. 2, 14871514, 2005 Unbiased estimate

    E-print Network

    Paris-Sud XI, Université de

    and waning of this important ecosystem through time. Although it is impossible to completely compensate be balanced by subsampling techniques based on weighted random draws from the available sampling pool (Alroy at the ecosystem level. Here I focus on the abundance (N) and volume (V ) of tropical reefs through the Phanerozoic

  1. Mössbauer Spectra of Some Iron Complexes

    Microsoft Academic Search

    L. M. Epstein

    1962-01-01

    Mossbauer spectra were obtained for the following coordthation ; compounds: iron phthalocyanine, ferrocene, iron carbonyl, iron HI ; acetylacetonate, and iron II acetylacetonate dipyridine; for the following ; complex ion saIts iron n trisphenanthroline chloride, iron W EDTA Monosodium ; salt), iron II EDTA, hemin, ferricium picrate, sodium nitroprusside, and some ; ferro- and ferricyanides. The isomer shift (relative to

  2. Power Spectra Estimation for Weak Lensing

    E-print Network

    Wayne Hu; Martin White

    2000-10-18

    We develop a method for estimating the shear power spectra from weak lensing observations and test it on simulated data. Our method describes the shear field in terms of angular power spectra and cross correlation of the two shear modes which differ under parity transformations. Two of the three power spectra can be used to monitor unknown sources of noise in the data. The power spectra are decomposed in a model independent manner in terms of ``band-powers'' which are then extracted from the data using a quadratic estimator to find the maximum of the likelihood and its local curvature (for error estimates). We test the method against simulated data from Gaussian realizations and cosmological N-body simulations. In the Gaussian case, the mean bandpowers and their covariance are well recovered even for irregular (or sparsely) sampled fields. The mild non-Gaussianity of the N-body realizations causes a slight underestimation of the errors that becomes negligible for scales much larger than several arcminutes and does not bias the recovered band powers.

  3. Chaotic spectra: How to extract dynamic information

    SciTech Connect

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

    1988-10-01

    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.

  4. Discriminating Dysarthria Type from Envelope Modulation Spectra

    ERIC Educational Resources Information Center

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

    2010-01-01

    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…

  5. CO2 retrievals from GOSAT glint spectra

    NASA Astrophysics Data System (ADS)

    Irion, F. W.; Frankenberg, C.; Natraj, V.; McDuffie, J.; O'Dell, C. W.

    2011-12-01

    Algorithms for retrieving column-averaged CO2 mixing ratio (XCO2) are being developed in preparation for the launch of the OCO-2 satellite. We describe features of the retrieval algorithm for observations made over ocean glint, and present current results for XCO2 using spectra from the Greenhouse Gases Observing Satellite (GOSAT) instrument currently in-flight.

  6. Calculated late time spectra of supernovae

    SciTech Connect

    Axelrod, T.S.

    1987-10-30

    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.

  7. Power station noise sources and spectra

    Microsoft Academic Search

    W. W. Avril; R. A. Popeck

    1977-01-01

    Sound sources within power station boundaries contribute to overall plant noise level with different energy levels, spectra, and radiation characteristics. This paper attempts to identify characteristics and describe major plant sound producing equipment and their noise producing mechanisms with octave band and narrower band width examples. Sound level measurements in the near field of noise source can sometimes distinguish its

  8. Porphyrins XIII: Fluorescence spectra and quantum yields

    Microsoft Academic Search

    Paul G. Seybold; Martin Gouterman

    1969-01-01

    Fluorescence spectra, quantum yields, natural radiative lifetimes, and absorption oscillator strengths are reported for a number of porphyrins in benzene solution. Emission yields for free base, Mg-, and Zn-phthalocyanine in 1-chloronaphthalene solution are also reported. The phthalocyanines are considerably more fluorescent than the porphyrins, and this is attributed mainly to their shorter radiative lifetimes. The heavy atom effect on fluorescence

  9. Computer simulation of the skin reflectance spectra

    Microsoft Academic Search

    I. V. Meglinski; S. J. Matcher

    2003-01-01

    The reflectance spectra of the human skin in visible and near-infrared (NIR) spectral region have been calculated using the Monte Carlo technique, and the specular and internal reflection on the medium surface is taken into account. Skin is represented as a complex inhomogeneous multi-layered highly scattering and absorbing medium. The model takes into account variations in spatial distribution of blood,

  10. Variations on supersymmetry breaking and neutrino spectra

    SciTech Connect

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

    2000-12-11

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

  11. Earth and Venus transmission spectra during transit

    E-print Network

    Widemann, Thomas

    Earth and Venus transmission spectra during transit 3rd Europlanet workshop ­ 4th PHC/Sakura meeting: Venus as a transiting exoplanet March 5 ­ 7 2012, Paris, France A. García Muñoz (Formerly at) Instituto de Astrofísica de Canarias, La Laguna, Spain Frank P. Mills (Venus work) The Australian National

  12. The Voigt profile of Mossbauer transmission spectra

    Microsoft Academic Search

    M. J. Evans; P. J. Black

    1970-01-01

    Mossbauer spectra, obtained with sources of 57Co in palladium and absorbers of sodium ferrocyanide, have been fitted to a Voigt profile by a procedure which enables the optimum values of the separate Lorentzian and Gaussian width components to be determined. Data from one source with absorbers of several different thicknesses suggest that most of the Gaussian broadening comes from the

  13. Analysis of COSIMA spectra: Bayesian approach

    NASA Astrophysics Data System (ADS)

    Lehto, H. J.; Zaprudin, B.; Lehto, K. M.; Lönnberg, T.; Silén, J.; Rynö, J.; Krüger, H.; Hilchenbach, M.; Kissel, J.

    2015-06-01

    We describe the use of Bayesian analysis methods applied to time-of-flight secondary ion mass spectrometer (TOF-SIMS) spectra. The method is applied to the COmetary Secondary Ion Mass Analyzer (COSIMA) TOF-SIMS mass spectra where the analysis can be broken into subgroups of lines close to integer mass values. The effects of the instrumental dead time are discussed in a new way. The method finds the joint probability density functions of measured line parameters (number of lines, and their widths, peak amplitudes, integrated amplitudes and positions). In the case of two or more lines, these distributions can take complex forms. The derived line parameters can be used to further calibrate the mass scaling of TOF-SIMS and to feed the results into other analysis methods such as multivariate analyses of spectra. We intend to use the method, first as a comprehensive tool to perform quantitative analysis of spectra, and second as a fast tool for studying interesting targets for obtaining additional TOF-SIMS measurements of the sample, a property unique to COSIMA. Finally, we point out that the Bayesian method can be thought of as a means to solve inverse problems but with forward calculations, only with no iterative corrections or other manipulation of the observed data.

  14. [Characteristics analysis of human tongue reflectance spectra].

    PubMed

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

    2014-08-01

    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

  15. [Characteristics analysis of human tongue reflectance spectra].

    PubMed

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

    2014-08-01

    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

  16. Toward global measurements of ocean wave spectra

    Microsoft Academic Search

    F. Jackson; W. Walton; P. Baker

    1982-01-01

    The development of a microwave radar technique for global, satellite measurement of ocean wave directional spectra has been a NASA goal for some years now. Our work at NASA Goddard, both experimental and theoretical, leads us to believe that we have found a simple, accurate, and economical solution to the global waves measurement problem. With some relatively minor modifications, these

  17. Interpretation of Infrared Spectra, A Practical Approach

    NSDL National Science Digital Library

    John Coates

    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.

  18. Squeezing spectra for nonlinear optical systems

    NASA Technical Reports Server (NTRS)

    Collett, M. J.; Walls, D. F.

    1985-01-01

    The squeezing spectra for the output fields of several intracavity nonlinear optical systems are obtained. It is shown that at critical points, e.g., the turning points for optical bistability, the threshold for parametric oscillation, and the self-pulsing instability in second-harmonic generation, perfect squeezing in the output field is, in principle, possible.

  19. Disk-averaged synthetic spectra of Mars

    E-print Network

    Tinetti, G; Fong, W; Meadows, V S; Snively, H; Velusamy, T; Crisp, David; Fong, William; Meadows, Victoria S.; Snively, Heather; Tinetti, Giovanna; Velusamy, Thangasamy

    2004-01-01

    The principal goal of the NASA Terrestrial Planet Finder (TPF) and ESA Darwin mission concepts is to directly detect and characterize extrasolar terrestrial (Earth-sized) planets. This first generation of instruments is expected to provide disk-averaged spectra with modest spectral resolution and signal-to-noise. Here we use a spatially and spectrally resolved model of the planet Mars to study the detectability of a planet's surface and atmospheric properties from disk-averaged spectra as a function of spectral resolution and wavelength range, for both the proposed visible coronograph (TPF-C) and mid-infrared interferometer (TPF-I/Darwin) architectures. At the core of our model is a spectrum-resolving (line-by-line) atmospheric/surface radiative transfer model which uses observational data as input to generate a database of spatially-resolved synthetic spectra for a range of illumination conditions (phase angles) and viewing geometries. Results presented here include disk averaged synthetic spectra, light-cur...

  20. CALCULATION OF ION ENERGY-DEPOSITION SPECTRA

    E-print Network

    Shultis, J. Kenneth

    CALCULATION OF ION ENERGY-DEPOSITION SPECTRA IN SILICON, LITHIUM-FLUORIDE, BORON, AND BORON CARBIDE Efficiency 13 4 Film-Coated Semiconductors 14 5 Stacked Slabs of Silicon and Converter 14 6 Semiconductor of their energy. Results are presented for media of boron, lithium fluoride, and silicon. A Monte Carlo procedure

  1. SAMPI: Protein Identification with Mass Spectra Alignments

    Microsoft Academic Search

    Hans-michael Kaltenbach; Andreas Wilke; Sebastian Böcker

    2007-01-01

    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

  2. ANALYSIS OF METHODS FOR DETECTING THE PROXIMITY EFFECT IN QUASAR SPECTRA

    SciTech Connect

    Dall'Aglio, Aldo [Astrophysikalisches Institut Potsdam, An der Sternwarte 16, D-14482 Potsdam (Germany); Gnedin, Nickolay Y., E-mail: adaglio@aip.d [Particle Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States)

    2010-10-10

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

  3. Improved predictions of reactor antineutrino spectra

    NASA Astrophysics Data System (ADS)

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

    2011-05-01

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

  4. Microwave Spectra of Fluoroformyloxyl and Fluorosulfate Radicals

    NASA Astrophysics Data System (ADS)

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

    2010-06-01

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

  5. Raman spectra of carotenoids in natural products

    NASA Astrophysics Data System (ADS)

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

    2003-08-01

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

  6. LMM Auger primary excitation spectra of copper

    NASA Astrophysics Data System (ADS)

    Pauly, N.; Tougaard, S.; Yubero, F.

    2014-12-01

    The shape and intensity of measured Auger peaks are strongly affected by extrinsic excitations due to electron transport out of the surface and to intrinsic excitations induced by the sudden creation of the two static core holes. Following a method developed for XPS in a previous work [N. Pauly, S. Tougaard, F. Yubero, Surf. Sci. 620 (2014) 17], we have calculated the effective energy-differential inelastic electron scattering cross-sections, including the effects of the surface and of the two core holes, within the dielectric response theory by means of the QUEELS-XPS software (QUantitative analysis of Electron Energy Losses at Surfaces for XPS). The Auger spectra are then modeled by convoluting this energy loss cross section with the primary excitation spectrum that accounts for all effects which are part of the initial Auger process, i.e. L-S coupling and vacancy satellite effects. The shape of this primary excitation spectrum is fitted to get close agreement between the theoretical and the experimental spectra obtained from X-ray excited Auger electron spectroscopy (XAES). We have performed these calculations of XAES spectra for various LMM Auger transitions of pure Cu (L3M45M45, L3M23M45, L3M23M23 and L2M45M45 transitions). We compare the resulting primary excitation spectra with theoretical results published in the literature and obtain reasonable quantitative agreement. In particular, we extract from experimental spectra quantitative intensities due to Coster-Kronig, shake-off and shake-up processes relative to the intensity from the “normal” Auger process.

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

    SciTech Connect

    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

    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.

  8. Evaluation of Algorithms for Reconstructing Electron Spectra from their Bremsstrahlung Hard X-Ray Spectra

    E-print Network

    Piana, Michele

    , enabling reconstruction of mean source electron energy spectra F(E) by deconvolution of photon energy. For real data F(E) is unknown, so the reliability of these various algorithms must instead be tested

  9. Specific heat spectra for quasiperiodic ladder sequences

    NASA Astrophysics Data System (ADS)

    Moreira, D. A.; Albuquerque, E. L.; Bezerra, C. G.

    2006-12-01

    We performed a theoretical study of the specific heat C(T) as a function of the temperature for double-strand quasiperiodic sequences. To mimic DNA molecules, the sequences are made up from the nucleotides guanine G, adenine A, cytosine C and thymine T, arranged according to the Fibonacci and Rudin-Shapiro quasiperiodic sequences. The energy spectra are calculated using the two-dimensional Schrödinger equation, in a tight-binding approximation, with the on-site energy exhibiting long-range disorder and non-random hopping amplitudes. We compare the specific heat features of these quasiperiodic artificial sequences to the spectra considering a segment of the first sequenced human chromosome 22 (Ch22), a real genomic DNA sequence.

  10. Analysis of spectra using correlation functions

    NASA Technical Reports Server (NTRS)

    Beer, Reinhard; Norton, Robert H.

    1988-01-01

    A novel method is presented for the quantitative analysis of spectra based on the properties of the cross correlation between a real spectrum and either a numerical synthesis or laboratory simulation. A new goodness-of-fit criterion called the heteromorphic coefficient H is proposed that has the property of being zero when a fit is achieved and varying smoothly through zero as the iteration proceeds, providing a powerful tool for automatic or near-automatic analysis. It is also shown that H can be rendered substantially noise-immune, permitting the analysis of very weak spectra well below the apparent noise level and, as a byproduct, providing Doppler shift and radial velocity information with excellent precision. The technique is in regular use in the Atmospheric Trace Molecule Spectroscopy (ATMOS) project and operates in an interactive, realtime computing environment with turn-around times of a few seconds or less.

  11. Inflation and alternatives with blue tensor spectra

    NASA Astrophysics Data System (ADS)

    Wang, Yi; Xue, Wei

    2014-10-01

    We study the tilt of the primordial gravitational waves spectrum. A hint of blue tilt is shown from analyzing the BICEP2 and POLARBEAR data. Motivated by this, we explore the possibilities of blue tensor spectra from the very early universe cosmology models, including null energy condition violating inflation, inflation with general initial conditions, and string gas cosmology, etc. For the simplest G-inflation, blue tensor spectrum also implies blue scalar spectrum. In general, the inflation models with blue tensor spectra indicate large non-Gaussianities. On the other hand, string gas cosmology predicts blue tensor spectrum with highly Gaussian fluctuations. If further experiments do confirm the blue tensor spectrum, non-Gaussianity becomes a distinguishing test between inflation and alternatives.

  12. Neutron Spectra in a 15 MV LINAC

    NASA Astrophysics Data System (ADS)

    Vega-Carrillo, H. R.; Chu, Wei-Han; Tung, Chuan-Jong; Lan, Jen-Hong

    2010-12-01

    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.

  13. Raman spectra of polycrystalline bismuth titanate nanotubes

    NASA Astrophysics Data System (ADS)

    Anokhin, A. S.; Lyanguzov, N. V.; Roshal', S. B.; Yuzyuk, Yu. I.; Wang, Wen

    2011-09-01

    The Raman spectra of bismuth titanate Bi4Ti3O12 nanotubes synthesized by the template method on an Al2O3 membrane have been studied. The samples prepared represent an array of oriented ˜50-?m-long nanotubes with coalescing smooth walls. The nanotube wall thickness is varied from 20 to 50 nm, and the nanotube inside diameter is about 200 nm. The Raman spectra of the nanotubes demonstrate a broadening of the lines corresponding to the stretching and bending vibrations of TiO6 octahedra. In the low-frequency spectral range corresponding to vibrations of Bi ions with respect to the oxygen octahedra, a transformation due to strong mechanical stresses generated during the formation of the nanotubes has been observed.

  14. Cathodoluminescence spectra of gallium nitride nanorods

    PubMed Central

    2011-01-01

    Gallium nitride [GaN] nanorods grown on a Si(111) substrate at 720°C via plasma-assisted molecular beam epitaxy were studied by field-emission electron microscopy and cathodoluminescence [CL]. The surface topography and optical properties of the GaN nanorod cluster and single GaN nanorod were measured and discussed. The defect-related CL spectra of GaN nanorods and their dependence on temperature were investigated. The CL spectra along the length of the individual GaN nanorod were also studied. The results reveal that the 3.2-eV peak comes from the structural defect at the interface between the GaN nanorod and Si substrate. The surface state emission of the single GaN nanorod is stronger as the diameter of the GaN nanorod becomes smaller due to an increased surface-to-volume ratio. PMID:22168896

  15. Creating semiconductor metafilms with designer absorption spectra.

    PubMed

    Kim, Soo Jin; Fan, Pengyu; Kang, Ju-Hyung; Brongersma, Mark L

    2015-01-01

    The optical properties of semiconductors are typically considered intrinsic and fixed. Here we leverage the rapid developments in the field of optical metamaterials to create ultrathin semiconductor metafilms with designer absorption spectra. We show how such metafilms can be constructed by placing one or more types of high-index semiconductor antennas into a dense array with subwavelength spacings. It is argued that the large absorption cross-section of semiconductor antennas and their weak near-field coupling open a unique opportunity to create strongly absorbing metafilms whose spectral absorption properties directly reflect those of the individual antennas. Using experiments and simulations, we demonstrate that near-unity absorption at one or more target wavelengths of interest can be achieved in a sub-50-nm-thick metafilm using judiciously sized and spaced Ge nanobeams. The ability to create semiconductor metafilms with custom absorption spectra opens up new design strategies for planar optoelectronic devices and solar cells. PMID:26184335

  16. Nuclear structure insights into reactor antineutrino spectra

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    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.

  17. Inflation and Alternatives with Blue Tensor Spectra

    E-print Network

    Yi Wang; Wei Xue

    2014-10-20

    We study the tilt of the primordial gravitational waves spectrum. A hint of blue tilt is shown from analyzing the BICEP2 and POLARBEAR data. Motivated by this, we explore the possibilities of blue tensor spectra from the very early universe cosmology models, including null energy condition violating inflation, inflation with general initial conditions, and string gas cosmology, etc. For the simplest G-inflation, blue tensor spectrum also implies blue scalar spectrum. In general, the inflation models with blue tensor spectra indicate large non-Gaussianities. On the other hand, string gas cosmology predicts blue tensor spectrum with highly Gaussian fluctuations. If further experiments do confirm the blue tensor spectrum, non-Gaussianity becomes a distinguishing test between inflation and alternatives.

  18. Raman spectra of deuteriated taurine single crystals

    NASA Astrophysics Data System (ADS)

    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

    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.

  19. Ab initio infrared and Raman spectra

    NASA Technical Reports Server (NTRS)

    Fredkin, D. R.; White, S. R.; Wilson, K. R.; Komornicki, A.

    1983-01-01

    It is pointed out that with increased computer power and improved computational techniques, such as the gradients developed in recent years, it is becoming practical to compute spectra ab initio, from the fundamental constants of nature, for systems of increasing complexity. The present investigation has the objective to explore several possible ab initio approaches to spectra, giving particular attention to infrared and nonresonance Raman. Two approaches are discussed. The sequential approach, in which first the electronic part and then later the nuclear part of the Born-Oppenheimer approximation is solved, is appropriate for small systems. The simultaneous approach, in which the electronic and nuclear parts are solved at the same time, is more appropriate for many-atom systems. A review of the newer quantum gradient techniques is provided, and the infrared and Raman spectral band contours for the water molecule are computed.

  20. Neutron Spectra in a 15 MV LINAC

    SciTech Connect

    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

    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.

  1. 8- to 13-micron spectra of asteroids

    NASA Astrophysics Data System (ADS)

    Green, S. F.; Eaton, N.; Aitken, D. K.; Roche, P. F.; Meadows, A. J.

    1985-05-01

    It is pointed out that thermal emission from asteroids reaches a maximum in the 10- to 20-micron region. In connection with the present investigation, a uniform set of spectra was obtained in the 8- to 13-micron region for 12 asteroids (together with additional observations of 19 Fortuna). These spectra provide a potentially valuable data set for future use (e.g., with IRAS data). The main conclusion from the obtained results is that diagnostic emission features of the type observed by Feierberg et al. (1983) are not common in C- and M-type asteroids. Optical studies of 19 Fortuna do not reveal any unusual properties which distinguish it from other C-type asteroids observed.

  2. Raman spectra of shocked minerals. I - Olivine

    NASA Technical Reports Server (NTRS)

    Heymann, D.; Celucci, T. A.

    1988-01-01

    The Raman spectra of olivine contained in a chip of the Twin Sisters Peak (Washington) dunite shocked to 22.2 GPa is shown to be identical to that of unshocked olivine in the same rock. The Raman spectra of powder of the rock shocked to 20.1 GPa and of chips shocked to 59.5 GPa and 60.7 GPa display strong and broad low-frequency features with crests at 475/cm, 556/cm, and 572/cm, and broad high-frequency features near 1100/cm. It is suggested that these features are due to the formation of olivine glass with a considerable degree of three-dimensional Si-O-Si linkage having scattered domains of greatly variable grain size, internal structure, and chemical composition.

  3. Principal component analysis of IUE galaxy spectra

    Microsoft Academic Search

    Liliana Formiggini; Noah Brosch

    2004-01-01

    We analyse the UV spectral energy distribution of a sample of normal galaxies\\u000alisted in the IUE-INES Guide No. 2-Normal Galaxies (Formiggini & Brosch, 2000)\\u000ausing a Principal Component Analysis. The sample consists of the IUE-SW spectra\\u000aof the central regions of 118 galaxies, where the IUE aperture included more\\u000athan 1 per cent of the galaxy size. The principal

  4. Spectra of Confined Atoms and Molecules

    Microsoft Academic Search

    D. Bielinska-Waz

    2003-01-01

    The properties of spectra of atoms and molecules confined by an external potential are analyzed. The effects of spatial confinement are studied using quantum-chemical models. The confinement of the system is described by an external one-particle potential. Two-electron atoms confined in a spherically symmetric harmonic oscillator potential are investigated in detail [1]. In this case the interplay between the effects

  5. Analysing Lyapunov spectra of chaotic dynamical systems

    E-print Network

    Fotis Diakonos; Detlef Pingel; Peter Schmelcher

    2000-06-07

    It is shown that the asymptotic spectra of finite-time Lyapunov exponents of a variety of fully chaotic dynamical systems can be understood in terms of a statistical analysis. Using random matrix theory we derive numerical and in particular analytical results which provide insights into the overall behaviour of the Lyapunov exponents particularly for strange attractors. The corresponding distributions for the unstable periodic orbits are investigated for comparison.

  6. Dielectronic satellite spectra of hydrogenlike titanium

    SciTech Connect

    Bhalla, C.P.; Karim, K.R.

    1986-10-01

    Theoretical atomic parameters calculated with the Z-expansion method and with the multiconfiguration Thomas-Fermi model set were recently reported and used in the analyses of dielectronic satellite spectra of hydrogenlike titanium observed from the Princeton Large Torus tokamak discharges. A comparison of our calculations, based on the Hartree-Fock-Slater atomic model, with the other two theoretical results show reasonable agreement with n -- 2 satellites but systematic and sometimes significant differences are found for n -- 3 and 4 satellites.

  7. Optical Absorption Spectra of Nanocrystal Gold Molecules

    Microsoft Academic Search

    Marcos M. Alvarez; Joseph T. Khoury; T. Gregory Schaaff; Marat N. Shafigullin; Igor Vezmar; Robert L. Whetten

    1997-01-01

    The optical absorption spectra of a series of nanocrystal gold moleculesslarger, crystalline Au clusters that are passivated by a compact monolayer of n-alkylthiol(ate)sshave been measured across the electronic range (1.1-4.0 eV) in dilute solution at ordinary temperature. Each of the20 samples, ranging in effective core diameter from 1.4 to 3.2 nm (70 to800 Au atoms), has been purified by fractional

  8. Increased Elemental Specificity of Positron Annihilation Spectra

    Microsoft Academic Search

    P. Asoka-Kumar; M. Alatalo; V. J. Ghosh; A. C. Kruseman; B. Nielsen; K. G. Lynn

    1996-01-01

    Positron annihilation spectroscopy (PAS) is a sensitive probe for studying the electronic structure of defects in solids. We show that the high-momentum part of the Doppler-broadened annihilation spectra can be used to distinguish different elements. This is achieved by using a new two-detector coincidence system to examine the line shape variations originating from high-momentum core electrons. Because the core electrons

  9. Parallel Genetic Algorithm for Alpha Spectra Fitting

    Microsoft Academic Search

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

    2005-01-01

    We present a performance study of alpha-particle spectra fitting using parallel Genetic Algorithm (GA). The method uses a two-step approach. In the first step we run parallel GA to find an initial solution for the second step, in which we use Levenberg-Marquardt (LM) method for a precise final fit. GA is a high resources-demanding method, so we use a Beowulf

  10. Ultraviolet photoelectron spectra of coinage metal clusters

    Microsoft Academic Search

    K. J. Taylor; C. L. Pettiette-Hall; O. Cheshnovsky; R. E. Smalley

    1992-01-01

    Ultraviolet photoelectron spectra (UPS) were recorded for mass-selected negative clusters of copper (1--411 atoms), silver (1--60 atoms), and gold (1--233 atoms), using photodetachment lasers at 6.4 and 7.9 eV photon energy. The results provide a direct estimate of the vertical electron affinity (EA) of these clusters and information on the evolution of the {ital d} bands of copper and gold

  11. Ultraviolet photoelectron spectra of coinage metal clusters

    Microsoft Academic Search

    K. J. Taylor; C. L. Pettiette-Hall; O. Cheshnovsky; R. E. Smalley

    1992-01-01

    Ultraviolet photoelectron spectra (UPS) were recorded for mass-selected negative clusters of copper (1–411 atoms), silver (1–60 atoms), and gold (1–233 atoms), using photodetachment lasers at 6.4 and 7.9 eV photon energy. The results provide a direct estimate of the vertical electron affinity (EA) of these clusters and information on the evolution of the d bands of copper and gold as

  12. Energy spectra of geomagnetically trapped oxygen ions

    Microsoft Academic Search

    M. Leicher; R. Beaujean; W. Enge

    1999-01-01

    In a series of COSMOS satellite flights plastic nuclear track detectors have been exposed in low-earth orbits to monitor anomalous cosmic rays (ACR) at energies below 25 MeV\\/nuc. The analysis of energy spectra has now been extended to energies up to 40 MeV\\/nuc for two exposures aboard COSMOS 2260 in 1993 and COSMOS 2311 in 1995. Our data on trapped

  13. Measurements of human sensitivity to combfiltered spectra

    Microsoft Academic Search

    V. Bonnardel; H. Bellemare; J. D. Mollon

    1996-01-01

    Using a novel stimulator that incorporates a liquid crystal display, the spectral modulation sensitivity tlmction of the colour vision system was derived by measuring discrimination thresholds for comb-filtered spectra. This function shows a peak of sensitivity at 0.97 c\\/300 nm with a plateau that extends to 1.67 c\\/300 nm. Extrapolation of the curve gives an estimated high-frequency cut-off at 5

  14. New USDA UVB synthetic spectra algorithm

    NASA Astrophysics Data System (ADS)

    Davis, John M.; Slusser, James R.

    2005-08-01

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

  15. Nonlinear Dielectric Relaxation Spectra of Polyvinyl Acetate

    Microsoft Academic Search

    Takeo Furukawa; Kiyokazu Matsumoto

    1992-01-01

    The frequency spectra of the linear and third nonlinear permittivities, \\\\varepsilon1* and \\\\varepsilon3*, have been measured for polyvinyl acetate (PVAc) at temperatures above Tg. The Debye relaxation of \\\\varepsilon1* associated with the micro-Brownian motion of noncrystalline segments is found to be accompanied by the complex frequency dependence of \\\\varepsilon3* due to combined contributions from the intrinsic nonlinear dielectricity and the

  16. Understanding the baryon and meson spectra

    SciTech Connect

    Pennington, Michael R. [JLAB

    2013-10-01

    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.

  17. Disk-Averaged Synthetic Spectra of Mars

    Microsoft Academic Search

    Giovanna Tinetti; Victoria S. Meadows; David Crisp; William Fong; Thangasamy Velusamy; Heather Snively

    2005-01-01

    The principal goal of the NASA Terrestrial Planet Finder (TPF) and European Space Agency's Darwin mission concepts is to directly detect and characterize extrasolar terrestrial (Earthsized) planets. This first generation of instruments is expected to provide disk-averaged spectra with modest spectral resolution and signal-to-noise. Here we use a spatially and spectrally resolved model of a Mars-like planet to study the

  18. VARIABILITY IN OPTICAL SPECTRA OF {epsilon} ORIONIS

    SciTech Connect

    Thompson, Gregory B. [Department of Physics, Adrian College, Adrian, MI 49221 (United States); Morrison, Nancy D., E-mail: gthompson@adrian.edu, E-mail: nmorris@utnet.utoledo.edu [Ritter Astrophysical Research Center, Department of Physics and Astronomy, University of Toledo, 2801 W. Bancroft, Toledo, OH 43606 (United States)

    2013-04-15

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

  19. IRAS Low Resolution Spectra of Asteroids

    NASA Technical Reports Server (NTRS)

    Cohen, Martin; Walker, Russell G.

    2002-01-01

    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.

  20. Optical spectra analysis for breast cancer diagnostics

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

    Minimally invasive probe and optical biopsy system based on optical spectra recording and analysis seem to be a promising tool for early diagnostics of breast cancer. Light scattering and absorption spectra are generated continuously as far as the needle-like probe with one emitting and several collecting optical fibers penetrates through the tissues toward to the suspicious area. That allows analyzing not only the state of local site, but also the structure of tissues along the needle trace. The suggested method has the advantages of automated on-line diagnosing and minimal tissue destruction and in parallel with the conventional diagnostic procedures provides the ground for decision-making. 165 medical trials were completed in Nizhny Novgorod Regional Oncology Centre, Russia. Independent diagnoses were the results of fine biopsy and histology. Application of wavelet expansion and clasterization techniques for spectra analysis revealed several main spectral types for malignant and benign tumors. Automatic classification algorithm demonstrated specificity ˜90% and sensitivity ˜91%. Large amount of information, fuzziness in criteria and data noisiness make neural networks to be an attractive analytic tool. The model based on three-layer perceptron was tested over the sample of 29 `cancer' and 29 `non-cancer' cases and demonstrated total separation.

  1. Infrared spectra of substituted polycylic aromatic hydrocarbons

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

    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.

  2. Computing High Accuracy Power Spectra with Pico

    E-print Network

    William A. Fendt; Benjamin D. Wandelt

    2007-12-02

    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.

  3. Mixing model analysis of telescopic lunar spectra

    NASA Technical Reports Server (NTRS)

    Lucey, Paul G.; Clark, Beth C.; Hawke, B. Ray

    1993-01-01

    We have analyzed very high quality reflectance spectra of the lunar surface from the University of Hawaii lunar spectral data collection using a spectral mixing model. The spectra analyzed are those of 45 mare sites and 75 highland sites. The spectra were selected on the basis of very high signal to noise ratios based on error bars and point to point scatter, and on quality of removal of telluric water bands. The spectral mixing model used 7 components, not all of which were used in each fit. Four of the components were mineral spectra of the orthopyroxene, a clinopyroxene, an olivine and an anorthite, measured at the Brown University's RELAB. All of the minerals were 45-90 micron splits. Lunar soil contains other components which have the effect of reddening and darkening the soil as well as reducing spectral contrast. In addition, lunar soil contains spectral neutral bright material (likely very fine grained feldspar) which serves to reduce spectral contrast and brighten soils. Early attempts to fit many of the spectra pointed out the need for a component which has a very broad smooth absorption feature centered near 1.1 microns. Glass is a good candidate for this component. For the bright component we used a flat reflectance of 70 percent to represent fine grained feldspar. For the 'glass' component we used a telescopic spectrum of a pyroclastic glass present on the Aristarchus plateau which is characterized by a strong smooth band centered at 1.07 microns. In addition to exhibiting the glass band this spectrum is very red and has a low albedo. On the assumption that the dark component and the red component are agglutinates, which is reasonable but not necessarily true, we sought a dark red component. To derive its properties we modelled the spectrum of an Apollo 16 soil (16xxx) and assumed the dark red component to comprise 60 percent of the soil, appropriate to agglutinate abundance in mature soil. We adjusted the albedo and slope of a straight line representing the dark red component until the contrast and albedo of the model spectrum matched the soil spectrum. The mixing was done after conversion to a single scattering albedo.

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

    PubMed Central

    Van de Moortele, Pierre-François; Auerbach, Edwards J.; Olman, Cheryl; Yacoub, Essa; U?urbil, Kâmil; Moeller, Steen

    2009-01-01

    At high magnetic field, MR images exhibit large, undesirable signal intensity variations commonly referred to as “intensity field bias”. Such inhomogeneities mostly originate from heterogeneous RF coil B1 profiles and, with no appropriate correction, are further pronounced when utilizing rooted sum of square reconstruction with receive coil arrays. These artifacts can significantly alter whole brain high resolution T1-weighted (T1w) images that are extensively utilized for clinical diagnosis, for gray/white matter segmentation as well as for coregistration with functional time series. In T1 weighted 3D-MPRAGE sequences, it is possible to preserve a bulk amount of T1 contrast through space by using adiabatic inversion RF pulses that are insensitive to transmit B1 variations above a minimum threshold. However, large intensity variations persist in the images, which are significantly more difficult to address at very high field where RF coil B1 profiles become more heterogeneous. Another characteristic of T1w MPRAGE sequences is their intrinsic sensitivity to Proton Density and T2* contrast, which cannot be removed with post-processing algorithms utilized to correct for receive coil sensitivity. In this paper, we demonstrate a simple technique capable of producing normalized, high resolution T1w 3D-MPRAGE images that are devoid of receive coil sensitivity, Proton Density and T2* contrast. These images, which are suitable for routinely obtaining whole brain tissue segmentation at 7 Tesla, provide higher T1 contrast specificity than standard MPRAGE acquisitions. Our results show that removing the Proton Density component can help identifying small brain structures and that T2* induced artifacts can be removed from the images. The resulting unbiased T1w images can also be used to generate Maximum Intensity Projection angiograms, without additional data acquisition, that are inherently registered with T1w structural images. In addition, we introduce a simple technique to reduce residual signal intensity variations induced by Transmit B1 heterogeneity. Because this approach requires two 3D images, one divided with the other, head motion could create serious problems, especially at high spatial resolution. To alleviate such inter-scan motion problems, we developed a new sequence where the two contrast acquisitions are interleaved within a single scan. This interleaved approach however comes with greater risk of intra-scan motion issues because of a longer single scan time. Users can choose between these two trade offs depending on specific protocols and patient populations. We believe that the simplicity and the robustness of this double contrast based approach to address intensity field bias at high field and improve T1 contrast specificity, together with the capability of simultaneously obtaining angiography maps, advantageously counter balance the potential drawbacks of the technique, mainly a longer acquisition time and a moderate reduction in signal to noise ratio. PMID:19233292

  5. Identifying Minerals from Their Infra-red Spectra.

    ERIC Educational Resources Information Center

    Paterson, W. G.

    1986-01-01

    Describes a British secondary school's use of a spectrometer to identify minerals. Discusses the origins of mineral spectra, the preparation of the specimen, the actual spectroscopic scanning, and the interpretation of the spectra. (TW)

  6. Infrared absorption spectra, radiative efficiencies, and global warming potentials

    E-print Network

    Wirosoetisno, Djoko

    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

  7. Classification of specialty seed meals from NIR reflectance spectra

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Near infrared reflectance spectroscopy was used to identify alternative seed meals proposed for food and feed formulations. Spectra were collected from cold pressed Camelina (Camelina sativa), Coriander (Coriandrum sativum), and Pennycress (Thlaspi arvense) meals. Additional spectra were collected ...

  8. Atlas of Synthetic Ultraviolet Spectra of Massive Star Populations

    Microsoft Academic Search

    Claus Leitherer; Carmelle Robert; Timothy M. Heckman

    1995-01-01

    An atlas of synthetic ultraviolet spectra of a population of massive stars is presented. The spectra are based on a stellar library of lUE high-dispersion spectra of O and Wolf-Rayet stars, coupled to an evolutionary synthesis code. Later spectral types are included via low-dispersion spectra. Line profiles of N V lambda1240, Si IV lambda1400, C IV lambda1550, He II lambda1640,

  9. Interpretation of the auger electron spectra (AES) of sulfide minerals

    Microsoft Academic Search

    David J. Vaughan; John A. Tossell

    1986-01-01

    Auger electron spectra (AES) of sulfides are interpreted using published photoelectron spectra, sulfurKß X-ray emission spectra (XES) and Multiple ScatteringXa calculations on metal-sulfide molecular clusters and using newly measured spectra for ZnS, Cu2S and MoS2. For compounds without appreciable metald-sulfur 3p interactions, only one sulfur LVV peak or a closely spaced doublet is observed. For those with substantial metald-sulfur 3p

  10. Proposed reference irradiance spectra for solar energy systems testing

    Microsoft Academic Search

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

    2002-01-01

    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

  11. Low energy particle composition. [energy spectra, particle emission - solar flares

    NASA Technical Reports Server (NTRS)

    Gloeckler, G.

    1975-01-01

    The energy spectra and composition of the steady or 'quiet-time' particle flux, whose origin is unknown was studied. Particles and photons which are associated with solar flares or active regions on the sun were also studied. Various detection techniques used to measure the composition and energy spectra of low energy particles are discussed. Graphs of elemental abundance and energy spectra are given.

  12. An atlas of optical spectra of white-dwarf stars

    Microsoft Academic Search

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

    1993-01-01

    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.

  13. Circular dichroism spectra of trans-chalcone epoxides

    Microsoft Academic Search

    Krisztina Pál; Mihály Kállay; Miklós Kubinyi; Péter Bakó; Attila Makó

    2007-01-01

    The electronic absorption and CD spectra of (?)-trans-chalcone epoxide and its derivatives with methyl and alkoxy substituents at the ortho-positions of the aromatic rings have been measured. The spectra have been assigned with help of the energies, oscillatory strengths, and rotatory strengths of the singlet transitions obtained from DFT calculations. The features of the CD spectra, indicative of the absolute

  14. Correcting second-order contamination in low-resolution spectra

    E-print Network

    V. Stanishev

    2007-05-23

    An empirical method for correcting low-resolution astronomical spectra for second-order contamination is presented. The method was developed for correcting spectra obtained with grism #4 of the ALFOSC spectrograph at the Nordic Optical Telescope and the performance is demonstrated on spectra of two nearby bright Type Ia supernovae.

  15. Acquisition of quality ?-ray spectra with HPGe spectrometers

    Microsoft Academic Search

    R. J. Gehrke; J. R. Davidson

    2005-01-01

    We propose practices to optimize the quality of acquired ?-ray spectra at a radioanalytical laboratory and to assist in the identification of extraneous spectral peaks including those from limitations in the physical setup, electronics, and counting conditions. This paper offers visible comparisons of high-quality spectra with those of inferior quality. We demonstrate the impacts on ?-ray spectra taken with germanium

  16. THE SPECTRA OF THE DOUBLY AND TRIPLY IONIZED RARE EARTHS

    Microsoft Academic Search

    G. H. Dieke; H. M. Crosswhite

    1963-01-01

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

  17. Introductory Use of Infrared Spectra: A Formalized Approach.

    ERIC Educational Resources Information Center

    McMinn, Dennis

    1984-01-01

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

  18. Infrared absorption spectra, radiative efficiencies, and global warming potentials

    E-print Network

    Wirosoetisno, Djoko

    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

  19. Infrared spectra of nitric and hydrochloric acid hydrate thin films

    Microsoft Academic Search

    Gary Ritzhaupt; J. Paul Devlin

    1991-01-01

    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

  20. Elastic–plastic response spectra for exponential blast loading

    Microsoft Academic Search

    Charis J. Gantes; Nikos G. Pnevmatikos

    2004-01-01

    The design of structures subjected to loads due to explosions is often treated by means of elastic–plastic response spectra. Such spectra that are currently available in the literature were computed on the basis of triangular shape of blast pressure with respect to time. In the present paper, response spectra based on an exponential distribution of blast pressure, which is in

  1. Theoretical Spectra of Unmagnetized Neutron Stars

    NASA Astrophysics Data System (ADS)

    Joss, Paul C.; Madej, Jerzy

    2001-09-01

    We have developed new models for the atmospheres of unmagnetized or weakly magnetized (B <= 1010 G) neutron stars with effective temperatures, Teff, in the range of 4× 106 K <= Teff <= 1× 107 K. Our model calculations include a full and accurate treatment of Compton scattering effects. We consider both pure hydrogen/helium atmospheres and atmospheres containing substantial amounts of iron (i.e., iron abundances at least as high as the solar value). Using our model atmospheres, we are able to determine the thermal X-ray emission spectrum of an unmagnetized neutron star as a function of Teff, surface gravity, and atmospheric chemical composition. We find, in particular, that the spectra of unmagnetized neutron stars with iron-rich atmospheres will feature absorption lines with complex structure that can, in principle, be at least partially resolved in observations that utilize the Chandra transmission gratings. We also find that the spectra of iron-rich atmospheres exhibit substantial flux deficits, relative to the spectra of hydrogen/helium atmospheres or simple blackbodies, at photon energies higher than the bound-free absorption edges of lithium-like and beryllium-like ions of iron at ~2 keV. This latter result provides a method of determining the presence and abundance of iron and/or other heavy elements in a neutron star atmosphere, without the need to resolve individual spectral lines. As described in a companion paper (Stage and Joss, these proceedings), we are currently using our results to fit Chandra observations of the point source in Cassiopeia A and other possible cases of thermal radiation by weakly magnetized neutron stars. This work was supported in part by the National Aeronautics and Space Administration under contract NAS8-38249 and by the Polish Committee for Scientific Research under grant No. 2 P03D 013 19.

  2. Prediction of peak overlap in NMR spectra.

    PubMed

    Hefke, Frederik; Schmucki, Roland; Güntert, Peter

    2013-06-01

    Peak overlap is one of the major factors complicating the analysis of biomolecular NMR spectra. We present a general method for predicting the extent of peak overlap in multidimensional NMR spectra and its validation using both, experimental data sets and Monte Carlo simulation. The method is based on knowledge of the magnetization transfer pathways of the NMR experiments and chemical shift statistics from the Biological Magnetic Resonance Data Bank. Assuming a normal distribution with characteristic mean value and standard deviation for the chemical shift of each observable atom, an analytic expression was derived for the expected overlap probability of the cross peaks. The analytical approach was verified to agree with the average peak overlap in a large number of individual peak lists simulated using the same chemical shift statistics. The method was applied to eight proteins, including an intrinsically disordered one, for which the prediction results could be compared with the actual overlap based on the experimentally measured chemical shifts. The extent of overlap predicted using only statistical chemical shift information was in good agreement with the overlap that was observed when the measured shifts were used in the virtual spectrum, except for the intrinsically disordered protein. Since the spectral complexity of a protein NMR spectrum is a crucial factor for protein structure determination, analytical overlap prediction can be used to identify potentially difficult proteins before conducting NMR experiments. Overlap predictions can be tailored to particular classes of proteins by preparing statistics from corresponding protein databases. The method is also suitable for optimizing recording parameters and labeling schemes for NMR experiments and improving the reliability of automated spectra analysis and protein structure determination. PMID:23585271

  3. Systematics of Identified Hadron Spectra at PHENIX

    E-print Network

    M. Csanad

    2006-03-02

    Mid-rapidity transverse momentum distributions for $\\pi^\\pm$, $K^\\pm$, p and $\\pbar$ are measured by the PHENIX experiment at RHIC in Au+Au, d+Au and p+p collisions at \\ssnn=200GeV up to ~2--4GeV. Also particle ratios of $\\pi^{-}/\\pi^{+}$, $K^{-}/K^{+}$, $\\pbar/p$, $p/\\pi$ and $\\pbar/\\pi$ are measured, as well as the nuclear modification factor, all as a function of \\pt and in every of the above collision systems. Finally, the measured p+p and Au+Au spectra are compared to the Buda-Lund hydro model.

  4. Benford's law and complex atomic spectra

    E-print Network

    Jean-Christophe Pain

    2008-01-07

    We found that in transition arrays of complex atomic spectra, the strengths of electric-dipolar lines obey Benford's law, which means that their significant digits follow a logarithmic distribution favoring the smallest values. This indicates that atomic processes result from the superposition of uncorrelated probability laws and that the occurrence of digits reflects the constraints induced by the selection rules. Furthermore, Benford's law can be a useful test of theoretical spectroscopic models. Its applicability to the statistics of electric-dipolar lines can be understood in the framework of random matrix theory and is consistent with the Porter-Thomas law.

  5. Momentum spectra, anisotropic flow, and ideal fluids

    E-print Network

    N. Borghini; J. -Y. Ollitrault

    2006-07-28

    If the matter produced in ultrarelativistic heavy-ion collisions reaches thermal equilibrium, its subsequent evolution follows the laws of ideal fluid dynamics. We show that general predictions can be made on this basis alone, irrespective of the details of the hydrodynamical model. We derive several scaling rules for momentum spectra and anisotropic flow (in particular the elliptic flow, v2, and the hexadecupole flow, v4) of identified particles. Comparison with existing data is briefly discussed, and qualitative predictions are made for LHC.

  6. Engineering upconversion emission spectra using plasmonic nanocavities.

    PubMed

    Lantigua, Christopher; He, Sha; Bouzan, Milad Akhlaghi; Hayenga, William; Johnson, Noah J J; Almutairi, Adah; Khajavikhan, Mercedeh

    2014-07-01

    We show that the upconversion emission spectra of Tm³? and Yb³? codoped ?-NaYF?-NaYF? core-shell nanoparticles can be judiciously modified by means of plasmonic nanocavities. Our analysis indicates that more than a 30-fold increase in conversion efficiency to the UV spectral band can be expected by engineering the NIR absorption and the local density of states. The effect of the nanocavity on the resulting radiation patterns is discussed. Our results are exemplified in cylindrical cavity geometries. PMID:24978717

  7. SPECTRA AND LIGHT CURVES OF FAILED SUPERNOVAE

    SciTech Connect

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

    2009-12-10

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

  8. Covariance Analysis of Gamma Ray Spectra

    SciTech Connect

    Trainham, R.; Tinsley, J.

    2013-01-01

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

  9. Nuclear reactor fissile isotopes antineutrino spectra

    E-print Network

    V. Sinev

    2012-07-30

    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.

  10. Energy Spectra from the ATIC Balloon Experiment

    NASA Astrophysics Data System (ADS)

    Isbert, Joachim; Adams, J. H.; Ahn, H. S.; Bashindzhagan, G. L.; Christl, M.; Fazeley, A. R.; Ganel, O.; Guzik, T. G.; Kim, K. C.; Kuznetsov, E. N.; Panasyuk, M. I.; Schmidt, W. K. H.; Seo, E. S.; Sokolskaya, N. V.; Watts, J. W.; Wefel, J. P.; Wu, J.; Zatsepin, V. I.

    2009-01-01

    The Advanced Thin Ionization Calorimeter (ATIC) Experiment has measured the energy spectra of individual elements, from H to Fe as well as the spectrum of electrons/positrons, in the energy region from about 100 GeV to tens of TeV. It was flown three times in long-duration balloon flights around the South Pole in 2001, 2003 and 2007 for a duration of 16, 19 and 14 days respectively and gathered data at an altitude of 36 km. In this poster we show results from these flights.

  11. Techniques for classifying acoustic resonant spectra

    SciTech Connect

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

    1995-12-31

    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.

  12. Modelling Spectra and Lightcurves from Supernovae

    NASA Astrophysics Data System (ADS)

    Frey, Lucille; Even, W.; Whalen, D.; Fryer, C.; Hungerford, A.; Fontes, C.

    2012-01-01

    Explosive transient astronomy is entering an era where supernovae (SNe) and gamma-ray bursts will be observed in real time with surveys like the LSST and Pan-STARRS, probing the universe back to very early times. The discovery of Pop III SNe could reveal many details about the formation and evolution of the first stars. Observations of shock breakout in SNe will provide new information about the engines powering these explosions. Shock breakout occurs when the shock wave from core collapse reaches an optically thin region and radiation can stream out. This first burst of radiation interacts with the star's immediate surroundings, showing the effects of the surrounding environment on emission and evolution. This profusion of data will contain brief snapshots from a wide range of progenitor systems which simulations can help interpret and explain. We present a new pipeline for creating model supernova spectra and lightcurves using radiation-hydrodynamic simulations and a new Spectrum code. Spectrum maps 1-D or 2-D data onto a two dimensional grid and assumes rotational symmetry, using monochromatic opacities to calculate emission and absorption as a function of radius and angle. We use these spectra to create lightcurves in any band from infrared to x-ray. This pipeline is being used to study the effects of stellar environment on core-collapse and Type Ia SNe, as well as several types of Pop III SNe.

  13. An atlas of selected calibrated stellar spectra

    NASA Technical Reports Server (NTRS)

    Walker, Russell G.; Cohen, Martin

    1992-01-01

    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.

  14. Blind Source Separation For Ion Mobility Spectra

    SciTech Connect

    Marco, S.; Pomareda, V. [Department of Electronics, University of Barcelona, C/Marti i Franques, no 1, planta 2, 08028, Barcelona (Spain); Artificial Olfaction Lab, Institute of BioEngineering of Catalonia and Institut de Bioenginyeria de Catalunya (IBEC), C/Baldiri Reixac 13, 08028 Barcelona (Spain); Pardo, A. [Department of Electronics, University of Barcelona, C/Marti i Franques, no 1, planta 2, 08028, Barcelona (Spain); Kessler, M.; Goebel, J.; Mueller, G. [Department LG-SI 2, EADS Innovation Works, EADS Deutschland GmbH and EADS Innovation Works, Dept. IW-SI-Sensors, Electronics and Systems Integration, 81663 Muenchen (Germany)

    2009-05-23

    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.

  15. Video-based ocean wave spectra

    SciTech Connect

    Harbitz, A. (Tromsoe Maritime Coll. (Norway))

    1994-07-01

    A particular video spot detector provides an irradiance time series from an arbitrarily chosen pixel in the video frame. The detector is applied to video records of the ocean surface, and the correspondence between the 1-D irradiance frequency spectrum and the corresponding ocean surface elevation spectrum is studied. A major experimental result is that the frequency peak in the irradiance spectrum for a typical wind-driven sea is significantly enhanced compared to the surface slope spectrum. Video experiments from the oil rig Gullfaks A in the North Sea show an excellent agreement between the enhanced peak frequency in the surface elevation spectrum measured by a microwave remote ocean surveillance wave radar. The enhancement of the peak in the irradiance spectrum is explained by a strong nonlinear geometrical projection effect. This is due to the rather small look angle with the horizontal, which is chosen so as to neglect irradiance contributions from beneath the sea surface. Based on a simple stochastic model that takes the geometric effect into account, irradiance spectra are simulated and are in good agreement with the experimental spectra.

  16. Infrared Spectra of Substituted Polycyclic Aromatic Hydrocarbons

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Hudgins, Douglas M.; Sandford, Scott A.; Allamandola, Louis J.; Arnold, James O. (Technical Monitor)

    1997-01-01

    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 amethyl or CN for a hydrogen does not significantly affect the spectrum other than to add the characteristic methyl C-H stretch and C-N stretch (near 2200/cm), 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 characteristics of the anthracene cation spectrum. The sum of the absolute intensities is about four times larger for 2-aminoanthracene than for 9-cyanoanthracene. Substituting nitrogen in the ring at the nine position (acridine) does not greatly alter the spectrum compared with anthracene.

  17. Power spectra of outflow-driven turbulence

    NASA Astrophysics Data System (ADS)

    Moraghan, Anthony; Kim, Jongsoo; Yoon, Suk-Jin

    2015-06-01

    We investigate the power spectra of outflow-driven turbulence through high-resolution three-dimensional isothermal numerical simulations where the turbulence is driven locally in real space by a simple spherical outflow model. The resulting turbulent flow saturates at an average Mach number of ˜2.5 and is analysed through density and velocity power spectra, including an investigation of the evolution of the solenoidal and compressional components. We obtain a shallow density power spectrum with a slope of ˜-1.2 attributed to the presence of a network of localized dense filamentary structures formed by strong shock interactions. The total velocity power spectrum slope is found to be ˜-2.0, representative of the Burgers shock-dominated turbulence model. The density-weighted velocity power spectrum slope is measured as ˜-1.6, slightly less than the expected Kolmogorov scaling value (slope of -5/3) found in previous works. The discrepancy may be caused by the nature of our real-space-driving model, and we suggest that there is no universal scaling law for supersonic compressible turbulence. We find that on average, solenoidal modes slightly dominate in our turbulence model as the interaction between strong curved compressible shocks generates solenoidal modes, and compressible modes decay faster.

  18. Unconstrained ocean wave spectra retrieval from SAR SLC imagery

    NASA Astrophysics Data System (ADS)

    Yang, Jingsong; Wang, He; Zhang, Rong; Chen, Xiaoyan; Huang, Weigen

    2008-12-01

    A new approach for directional ocean wave spectra retrieval from synthetic aperture radar (SAR) single look complex (SLC) imagery is presented. This method takes the advantages of both Engen's cross spectra method and Lyzenga's unconstrained inversion method. It consists of following three main steps: (1) split-look processing and cross-spectra estimation of SLC imagery; (2) unconstrained iteration of ocean wave spectra with 180° direction ambiguity from real part of cross-spectra; (3) remove the 180° ambiguity from imaginary part of cross-spectra. Envisat ASAR data are used in cases studies. Wavelength, wave direction and significant wave height (SWH) are also derived from retrieved ocean wave spectra. Case studies with comparisons show that this method reaches better results than the one used by ESA. It can avoid the inherent error of the latter.

  19. Infrared Spectra of Polycyclic Aromatic Hydrocarbons: Nitrogen Substitution

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W.; Arnold, James O. (Technical Monitor)

    1998-01-01

    The B3LYP/4-31G approach is used to compute the harmonic frequencies of substituted naphthalene, anthracene, and their cations. The substitutions include cyano (CN), aminio (NH2), imino (NH), and replacement of a CH group by a nitrogen atom. All unique sites are considered, namely 1 and 2 for naphthalene and 1, 2, and 9 for an'tracene, except for the imino, where only 2-iminonaphthalene is studied. The IR spectra of these substituted species are compared with those of the unsubstituted molecules. The addition of a CN group does not significantly affect the spectra except to add the CN stretching frequency. Replacing a CH group by N has only a small effect on the IR spectra. The addition of the NH2 group dramatically affects the neutral spectra, giving it much of the character of the cation spectra. However, the neutral 2-irrinonaphthalene spectra looks more like that of naphthalene than like the 2-aminonaphthalene spectra.

  20. Automatic one dimensional spectra extraction for Weihai fiber-fed high resolution echelle spectra

    NASA Astrophysics Data System (ADS)

    Hu, Shao Ming; Gao, Dong Yang

    2014-11-01

    One fiber-fed high resolution echelle spectrograph was built for the one meter telescope atWeihai Observatory of Shandong University. It is used for exoplanet searching by radial velocity method and for stellar spectra analysis. One dimensional spectra extraction from the raw echelle data is researched in this paper. Flat field images with different exposure times were used to trace the order position accurately. The accurate background was fitted from each CCD image and it was subtracted from the raw image to correct the background and straylight. The intensity of each order decreases towards the order margin, and the lengths of order are different between the blue and red regions. The order tracing during the data reduction was investigated in this work. Accurate flux can be obtained after considering the effects of bad pixels, the curvature of each order and so on. One Interactive Data Language program for one dimensional spectra extraction was adopted and implemented to echelle data reduction for Weihai fiber-fed high resolution echelle spectra, and the results are illustrated here. The program is efficient and accurate for echelle data reduction. It can be adopted to reduce data taken by other instruments even the spectrographs in other fields, and it is very convenient for astronomers.

  1. [The monomer electronic spectra and fluorescence spectra of some metal phthalocyanines].

    PubMed

    Huang, J; Liu, E; Yang, S; Chen, N; Huang, J; Duan, J; Chen, Y

    2000-02-01

    The monomer electronic absorption spectra of the ZnPcS2P2 (disulfonated diphthalimidomethyl phthalocyanine zinc) in 11 kinds of solvents and 5 kinds of unsubstituted metal phthalocyanines in DMF were investigated. The monomer electronic absorption spectra of some substituted phthalocyanine zinc including ZnPcS4 (tetrasulfonated phthalocyanine zinc), ZnPcS4 (tetraphthalimidomethyl phthalocyanine zinc), ZnPc(NO2)4 (tetranitro phthalocyanine zinc) and ZnPcS2P2 in the same solvent were also studied. The result showed that (1) with the strengthening of coordination ability of the solvent, the maximum absorption wavelength of ZnPcS2P2 increased slightly. (2) with the increasing of electronegativity of central ion, the maximum absorption wavelength of MPcs had a little blue shift. (3) the electron-donating substituting group caused slightly blue shift. The monomer fluorescence spectra of ZnPcS4, ZnPcP4, and ZnPcS2P2 in different solvents were determined. The result showed that (1) the electron-withdrawing substituting group caused slightly red shift of the fluorescence spectra. (2) with the strenghtening of coordination ability of the solvent, the maximum emission wavelength increased slightly. (3) the fluorescence intensity of ZnPcS2P2 in the solution which contains Cremophor EL was remarkable stronger than that in other solvents. This is an important suggest to the development of photodynamic diagnose agent. The effect of solvents, central ions and substituents on spectra were partly explained by means of the quantrum chemistry. PMID:12953463

  2. Oxidation of carbynes: Signatures in infrared spectra

    SciTech Connect

    Cinquanta, E., E-mail: eugenio.cinquanta@mdm.imm.cnr.it, E-mail: p.rudolf@rug.nl [CIMAINA, University of Milan, Via Celoria 16, 20133 Milano (Italy); Department of Materials Science, University of Milan Bicocca, Via Cozzi 53, 20125 Milano (Italy); Manini, N.; Caramella, L.; Onida, G. [European Theoretical Spectroscopy Facility (ETSF), Via Celoria 16, 20133 Milano (Italy); Physics Department, University of Milan, Via Celoria 16, 20133 Milano (Italy); Ravagnan, L.; Milani, P. [CIMAINA, University of Milan, Via Celoria 16, 20133 Milano (Italy); Physics Department, University of Milan, Via Celoria 16, 20133 Milano (Italy); Rudolf, P., E-mail: eugenio.cinquanta@mdm.imm.cnr.it, E-mail: p.rudolf@rug.nl [Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747AG Groningen (Netherlands)

    2014-06-28

    We report and solidly interpret the infrared spectrum of both pristine and oxidized carbynes embedded in a pure-carbon matrix. The spectra probe separately the effects of oxidation on sp- and on sp{sup 2}-hybridized carbon, and provide information on the stability of the different structures in an oxidizing atmosphere. The final products are mostly short end-oxidized carbynes anchored with a double bond to sp{sup 2} fragments, plus an oxidized sp{sup 2} amorphous matrix. Our results have important implications for the realization of carbyne-based nano-electronics devices and highlight the active participation of carbynes in astrochemical reactions where they act as carbon source for the promotion of more complex organic species.

  3. X ray spectra of cataclysmic variables

    NASA Technical Reports Server (NTRS)

    Patterson, Joseph; Halpern, Jules

    1990-01-01

    X ray spectral parameters of cataclysmic variables observed with the 'Einstein' imaging proportional counter were determined by fitting an optically thin, thermal bremsstrahlung spectrum to the raw data. Most of the sources show temperatures of order a few keV, while a few sources exhibit harder spectra with temperatures in excess of 10 keV. Estimated 0.1 to 3.5 keV luminosities are generally in the range from 10(exp 30) to 10(exp 32) erg/sec. The results are consistent with the x rays originating in a disk/white dwarf boundary layer of non-magnetic systems, or in a hot, post-shock region in the accretion column of DQ Her stars, with a negligible contribution from the corona of the companion. In a few objects column densities were found that are unusually high for interstellar material. It was suggested that the absorption occurs in the system itself.

  4. Vibrational spectra and DFT calculations of squalene

    NASA Astrophysics Data System (ADS)

    Chun, Hye Jin; Weiss, Taylor L.; Devarenne, Timothy P.; Laane, Jaan

    2013-01-01

    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.

  5. Spectra as windows into exoplanet atmospheres.

    PubMed

    Burrows, Adam S

    2014-09-01

    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

  6. Tunneling spectra simulation of interacting Majorana wires

    NASA Astrophysics Data System (ADS)

    Thomale, Ronny; Rachel, Stephan; Schmitteckert, Peter

    2013-10-01

    Recent tunneling experiments on InSb hybrid superconductor-semiconductor devices have provided hope for a stabilization of Majorana edge modes in a spin-orbit quantum wire subject to a magnetic field and superconducting proximity effect. Connecting the experimental scenario with a microscopic description poses challenges of a different kind, such as accounting for the effect of interactions on the tunneling properties of the wire. We develop a density matrix renormalization group (DMRG) analysis of the tunneling spectra of interacting Majorana chains, which we explicate for the Kitaev chain model. Our DMRG approach allows us to calculate the spectral function down to zero frequency, where we analyze how the Majorana zero-bias peak is affected by interactions. For topological phase transitions between the topological and trivial superconducting phase in the Majorana wire, the bulk gap closure generically affects the proximity peaks and the Majorana peak.

  7. On Magnetic Spectra of Earth and Mars

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

    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.

  8. Matching the linear spectra of twinlike defects

    E-print Network

    Yuan Zhong; Yu-Xiao Liu

    2014-08-27

    Twinlike defects refer to topological defect solutions of some apparently different field models that share the same defect configuration and the same energy density. Usually, one can distinguish twinlike defects in terms of their linear spectra, but in some special cases twinlike defects even share the same linear spectrum. In a recent publication [C. Adam and J. Queiruga, Phys. Rev. D 85, 025019 (2012)], the authors investigated the algebraic conditions for two twinlike defects that have identical linear spectrum. In this paper, we reexamine these algebraic conditions from the viewpoint of the normal modes of the linear fluctuations. We obtain a simpler but less restricted algebraic condition. Our results open a new window for interesting models that violate the algebraic constraints in Adam-Queiruga's construction. We also extend our discussion to braneworld models, where gravity plays an important role.

  9. UV spectra, bombs, and the solar atmosphere

    E-print Network

    Judge, Philip G

    2015-01-01

    A recent analysis of UV data from the Interface Region Imaging Spectrograph {\\em IRIS} reports plasma "bombs" with temperatures near \\hot{} within the solar photosphere. This is a curious result, firstly because most bomb plasma pressures $p$ (the largest reported case exceeds $10^3$ dyn~cm$^{-2}$) fall well below photospheric pressures ($> 7\\times10^3$), and secondly, UV radiation cannot easily escape from the photosphere. In the present paper the {\\em IRIS} data is independently analyzed. I find that the bombs arise from plasma originally at pressures between $\\lta80$ and 800 dyne~cm$^{-2}$ before explosion, i.e. between $\\lta850$ and 550 km above $\\tau_{500}=1$. This places the phenomenon's origin in the low-mid chromosphere or above. I suggest that bomb spectra are more compatible with Alfv\\'enic turbulence than with bi-directional reconnection jets.

  10. Radiation spectra and polarization in magnetar bursts

    E-print Network

    Jacek Niemiec; Tomasz Bulik

    2005-02-21

    We present Monte Carlo simulations of radiative transfer in magnetar atmospheres. We include the effects of vacuum polarization, electron and proton scattering, and free-free absorption. Simulations are performed for the atmosphere model with the magnetic field perpendicular and also tilted with respect to the neutron star surface, and we show that the average spectrum does not strongly depend on the orientation of the magnetic field. We investigate the region of the parameter space where the vacuum absorption-like feature appears in the spectrum and we analyze the shape of the proton cyclotron line. Our results indicate that the existence of the vacuum polarization feature should be a general attribute of soft gamma-ray repeaters burst spectra, provided that the energy release takes place at the sufficiently dense region, and the atmosphere scaleheight is large enough. We discuss the existence of such a feature in recent observational data on these sources.

  11. Jets and Bombs: Characterizing IRIS Spectra

    NASA Astrophysics Data System (ADS)

    Schmit, Donald; Innes, Davina

    2014-06-01

    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.

  12. Longslit Spectra of the Galaxy NGC 1569

    NASA Technical Reports Server (NTRS)

    Duenas, Ely

    2000-01-01

    Longslit spectra of the starburst galaxy NGC 1569 are displayed. This ground-based data was acquired at the 90-inch telescope of the Steward Observatory (Kitt Peak, Arizona) in September 1998. Results for the red region of the spectrum are presented. The variation of ionization and gas density as a function of position in the galaxy are shown. The background stellar component of the galaxy is separated from the nebular emission spectrum. These ground-based results will be used with space-based data to be acquired by astronomers at South Carolina State University, the University of Maryland and Rice University as part of an approved Cycle 8 Hubble Space Telescope program.

  13. Longslit Spectra of the Galaxy NGC 1569

    NASA Astrophysics Data System (ADS)

    Duenas, Ely

    2000-11-01

    Longslit spectra of the starburst galaxy NGC 1569 are displayed. This ground-based data was acquired at the 90-inch telescope of the Steward Observatory (Kitt Peak, Arizona) in September 1998. Results for the red region of the spectrum are presented. The variation of ionization and gas density as a function of position in the galaxy are shown. The background stellar component of the galaxy is separated from the nebular emission spectrum. These ground-based results will be used with space-based data to be acquired by astronomers at South Carolina State University, the University of Maryland and Rice University as part of an approved Cycle 8 Hubble Space Telescope program.

  14. [Temperature dependence of collagen by Raman spectra].

    PubMed

    Dong, Rui-xin; Yan, Xun-ling; Jiang, Shan; Liu, Mei-jie; Liu, Sheng-gang

    2004-11-01

    Raman spectra of collagen I at different temperature were obtained. There was no change at 1003 cm(-1) line, 1302 cm(-1) line moved to a higher wave number, but other lines moved to lower wave number when temperature increased. In addition, the authors observed the temperature dependence of Raman intensity and four denaturation points at 0, 40, 68 and 90 degrees C respectively. The points at 40 and 68 degrees C are in agreement with the experimental data by DSC and SHG. The point at 0 degrees C might be frozen transition; the point at 90 degrees C might be related to the damage of secondary structure. When heated to 150 degrees C, the Raman intensity of all bands decreased rapidly and many lines disappeared. PMID:15762478

  15. Ultraviolet photoelectron spectra of coinage metal clusters

    SciTech Connect

    Taylor, K.J.; Pettiette-Hall, C.L.; Cheshnovsky, O.; Smalley, R.E. (Rice Quantum Institute and Departments of Chemistry and Physics, Rice University, Houston, Texas 77251 (United States))

    1992-02-15

    Ultraviolet photoelectron spectra (UPS) were recorded for mass-selected negative clusters of copper (1--411 atoms), silver (1--60 atoms), and gold (1--233 atoms), using photodetachment lasers at 6.4 and 7.9 eV photon energy. The results provide a direct estimate of the vertical electron affinity (EA) of these clusters and information on the evolution of the {ital d} bands of copper and gold as a function of cluster size. The large even/odd alternation of EA in small clusters of these metals in earlier work is found to largely disappear as the cluster size exceeds 40 atoms. The ellipsoidal shell model is shown to be consistent with the observed EA behavior of all three metals, the predicted spherical shell closing at cluster 58 being evident for silver and gold. The UPS data show a smooth evolution of the {ital d} band toward that of the bulk metal.

  16. Gas Cell Development for Infrared Spectra Calibration

    NASA Astrophysics Data System (ADS)

    Valdivielso, Luisa; Esparza, Pedro; Martín, Eduardo L.

    NAHUAL is a high-resolution near-infrared echelle spectrograph of high stability on preliminary phase development for GTC (Gran Telescopio de Canarias). Its natural location is a Nasmyth focus. One of the principal scientific aims is to carry out high precision radial velocity measurements (from 1 to 10 m/s) in the near infrared. To achieve high stability on radial velocity measurements, NAHUAL needs a calibration unit that uses a mixture of gases whose absorption spectra must be as homogeneous as possible between 0.95 and 2.4 ?m. We report on the measurements done to date with potentially active gas mixtures as acetylene, methane, nitrous oxide or hydrocarbons.

  17. Optical absorption spectra of dications of carotenoids

    SciTech Connect

    Jeevarajan, J.A.; Wei, C.C.; Jeevarajan, A.S.; Kispert, L.D. [Univ. of Alabama, Tuscaloosa, AL (United States)] [Univ. of Alabama, Tuscaloosa, AL (United States)

    1996-04-04

    Quantitative optical absorption spectra of the cation radicals and the dications of canthaxanthin (I), {beta}carotene (II), 7`-cyano-7`-ethoxycarbonyl-7`-apo-{beta}-carotene (III), and 7`,7`-dimethyl-7`-apo-{beta}-carotene (IV) in dichloromethane solution are reported. Exclusive formation of dications occurs when the carotenoids are oxidized with ferric chloride. Addition of neutral carotenoid to the dications results in equilibrium formation of cation radicals. Oxidation with iodine in dichloromethane affords only cation radicals; electrochemical oxidation under suitable conditions yields both dications and cation radicals. Values of the optical parameters depend on the nature of the oxidative medium. The oscillator strengths calculated for gas phase cation radicals and dications of I-IV using the INDO/S method show the same trend as the experimental values. 31 refs., 4 figs., 2 tabs.

  18. Spectra of functionalized operators arising from hypersurfaces

    NASA Astrophysics Data System (ADS)

    Hayrapetyan, Gurgen; Promislow, Keith

    2015-06-01

    Functionalized energies, such as the Functionalized Cahn-Hilliard, model phase separation in amphiphilic systems, in which interface production is limited by the competition for surfactant phase, which wets the interface. This is in contrast to classical phase-separating energies, such as the Cahn-Hilliard, in which interfacial area is energetically penalized. In binary amphiphilic mixtures, interfaces are characterized not by single layers, which separate domains of phase A from those of phase B via a heteroclinic connection, but by bilayers, which divide the domain of the dominant phase, A, via thin layers of phase B formed by homoclinic connections. Evaluating the second variation of the functionalized energy at a bilayer interface yields a functionalized operator. We characterize the center-unstable spectra of functionalized operators and obtain resolvent estimates to the operators associated with gradient flows of the functionalized energies. This is an essential step to a rigorous reduction to a sharp-interface limit.

  19. Satellite spectra for helium-like titanium

    SciTech Connect

    Bely-Dubac, F.; Faucher, P.; Steeman-Clark, L.; Dubau, J.; Cammy-Val, C.; Bitter, M.; Hill, K.W.; von Goeler, S.

    1982-06-01

    Wavelengths and atomic parameters for both dielectronic and inner-shell satellite lines of the type ls/sup 2/ nl - 1s2l' nl, with n = 2, 3, and 4, have been calculated for Ti XX. The atomic data were calculated in a multiconfiguration intermediate coupling scheme and are compared with previous results for n = 2. The intensities of the higher n satellites are derived from these data, and thus an estimate of the contribution of the unresolved dielectronic satellites to the resonance line is obtained. Direct excitation rates are also given for the resonance, intercombination and forbidden lines for He-like titanium. Cascades and the effect of resonances for these lines are not considered in this paper. These results are used to fit an experimental soft x-ray spectrum from the PDX (Poloidal Divertor Experiment) tokamak discharge. Good agreement is obtained between computed and observed spectra.

  20. Radioactive sample effects on EDXRF spectra

    SciTech Connect

    Worley, Christopher G [Los Alamos National Laboratory

    2008-01-01

    Energy dispersive X-ray fluorescence (EDXRF) is a rapid, straightforward method to determine sample elemental composition. A spectrum can be collected in a few minutes or less, and elemental content can be determined easily if there is adequate energy resolution. Radioactive alpha emitters, however, emit X-rays during the alpha decay process that complicate spectral interpretation. This is particularly noticeable when using a portable instrument where the detector is located in close proximity to the instrument analysis window held against the sample. A portable EDXRF instrument was used to collect spectra from specimens containing plutonium-239 (a moderate alpha emitter) and americium-241 (a heavy alpha emitter). These specimens were then analyzed with a wavelength dispersive XRF (WDXRF) instrument to demonstrate the differences to which sample radiation-induced X-ray emission affects the detectors on these two types of XRF instruments.

  1. Introduction to the Surface Spectra of Oxides

    SciTech Connect

    Baer, D.R. [William R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington (United States)] [William R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington (United States); Henrich, V.E. [Department of Applied Physics, Yale University, New Haven, Connecticut (United States)] [Department of Applied Physics, Yale University, New Haven, Connecticut (United States)

    1996-07-01

    Due to their technological importance and an increasing scientific interest, a set of data from oxide surfaces has been collected for publication in two special issues of {ital Surface Science Spectra}. This Introduction to these two special issues summarizes the data to be presented and provides short overviews of trends in both the physics and chemistry of metal-oxide surfaces and of some important aspects of the techniques used to examine these surfaces. The surface spectroscopies discussed in relation to oxides include: valence band photoemission (ultraviolet photoelectron spectroscopy and synchrotron based), core level photoemission (x-ray photoelectron spectroscopy, XPS), Auger electron spectroscopy (AES), (reflection) electron energy loss spectroscopy (R)EELS, high-resolution electron energy loss spectroscopy (HREELS), scanning probe methods, and ion scattering spectroscopy (ISS). Brief sections also discuss the nature of stoichiometric oxide surfaces, the physics and chemistry of defects on these surfaces, and adsorption on metal-oxide surfaces.{copyright} {ital 1998 American Vacuum Society.}

  2. Turbulent velocity spectra in superfluid flows

    NASA Astrophysics Data System (ADS)

    Salort, J.; Baudet, C.; Castaing, B.; Chabaud, B.; Daviaud, F.; Didelot, T.; Diribarne, P.; Dubrulle, B.; Gagne, Y.; Gauthier, F.; Girard, A.; Hébral, B.; Rousset, B.; Thibault, P.; Roche, P.-E.

    2010-12-01

    We present velocity spectra measured in three cryogenic liquid H4e steady flows: grid and wake flows in a pressurized wind tunnel capable of achieving mean velocities up to 5 m/s at temperatures above and below the superfluid transition, down to 1.7 K, and a "chunk" turbulence flow at 1.55 K, capable of sustaining mean superfluid velocities up to 1.3 m/s. Depending on the flows, the stagnation pressure probes used for anemometry are resolving from one to two decades of the inertial regime of the turbulent cascade. We do not find any evidence that the second-order statistics of turbulence below the superfluid transition differ from the ones of classical turbulence, above the transition.

  3. Spectra as Windows into Exoplanet Atmospheres

    E-print Network

    Burrows, Adam

    2013-01-01

    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 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. Though not a review in any sense, this paper highlights the limitations in our knowledge of compositions, thermal profiles, and the effects of stellar irradiation, focussing 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 that, by rapid trial and error, is fast establishing a solid future foundation for a robust sc...

  4. Fluctuation spectra of weakly driven nonlinear systems

    E-print Network

    Yaxing Zhang; Yukihiro Tadokoro; M. I. Dykman

    2015-01-15

    We show that in periodically driven systems, along with the delta-peak at the driving frequency, the spectral density of fluctuations displays extra features. These can be peaks or dips with height quadratic in the driving amplitude, for weak driving. For systems where inertial effects can be disregarded, the peaks/dips are generally located at zero frequency and at the driving frequency. The shape and intensity of the spectra very sensitively depend on the parameters of the system dynamics. To illustrate this sensitivity and the generality of the effect, we study three types of systems: an overdamped Brownian particle (e.g., an optically trapped particle), a two-state system that switches between the states at random, and a noisy threshold detector. The analytical results are in excellent agreement with numerical simulations.

  5. CO2 profile retrievals from TCCON spectra

    NASA Astrophysics Data System (ADS)

    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

    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.

  6. Spectra of small Koronis family members

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    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.

  7. HF Accelerated Electron Fluxes, Spectra, and Ionization

    NASA Astrophysics Data System (ADS)

    Carlson, Herbert C.; Jensen, Joseph B.

    2014-12-01

    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.

  8. THEORETICAL SPECTRA OF TERRESTRIAL EXOPLANET SURFACES

    SciTech Connect

    Hu Renyu; Seager, Sara [Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Ehlmann, Bethany L., E-mail: hury@mit.edu [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States)

    2012-06-10

    We investigate spectra of airless rocky exoplanets with a theoretical framework that self-consistently treats reflection and thermal emission. We find that a silicate surface on an exoplanet is spectroscopically detectable via prominent Si-O features in the thermal emission bands of 7-13 {mu}m and 15-25 {mu}m. The variation of brightness temperature due to the silicate features can be up to 20 K for an airless Earth analog, and the silicate features are wide enough to be distinguished from atmospheric features with relatively high resolution spectra. The surface characterization thus provides a method to unambiguously identify a rocky exoplanet. Furthermore, identification of specific rocky surface types is possible with the planet's reflectance spectrum in near-infrared broad bands. A key parameter to observe is the difference between K-band and J-band geometric albedos (A{sub g}(K) - A{sub g}(J)): A{sub g}(K) - A{sub g}(J) > 0.2 indicates that more than half of the planet's surface has abundant mafic minerals, such as olivine and pyroxene, in other words primary crust from a magma ocean or high-temperature lavas; A{sub g}(K) - A{sub g}(J) < -0.09 indicates that more than half of the planet's surface is covered or partially covered by water ice or hydrated silicates, implying extant or past water on its surface. Also, surface water ice can be specifically distinguished by an H-band geometric albedo lower than the J-band geometric albedo. The surface features can be distinguished from possible atmospheric features with molecule identification of atmospheric species by transmission spectroscopy. We therefore propose that mid-infrared spectroscopy of exoplanets may detect rocky surfaces, and near-infrared spectrophotometry may identify ultramafic surfaces, hydrated surfaces, and water ice.

  9. Polarization effects in cutaneous autofluorescent spectra

    NASA Astrophysics Data System (ADS)

    Borisova, E.; Angelova, L.; Jeliazkova, Al.; Genova, Ts.; Pavlova, E.; Troyanova, P.; Avramov, L.

    2014-05-01

    Used polarized light for fluorescence excitation one could obtain response related to the anisotropy features of extracellular matrix. The fluorophore anisotropy is attenuated during lesions' growth and level of such decrease could be correlated with the stage of tumor development. Our preliminary investigations are based on in vivo point-by-point measurements of excitation-emission matrices (EEM) from healthy volunteers skin on different ages and from different anatomical places using linear polarizer and analyzer for excitation and emission light detected. Measurements were made using spectrofluorimeter FluoroLog 3 (HORIBA Jobin Yvon, France) with fiber-optic probe in steady-state regime using excitation in the region of 280-440 nm. Three different situations were evaluated and corresponding excitation-emission matrices were developed - with parallel and perpendicular positions for linear polarizer and analyzer, and without polarization of excitation and fluorescence light detected from a forearm skin surface. The fluorescence spectra obtained reveal differences in spectral intensity, related to general attenuation, due to filtering effects of used polarizer/analyzer couple. Significant spectral shape changes were observed for the complex autofluorescence signal detected, which correlated with collagen and protein cross-links fluorescence, that could be addressed to the tissue extracellular matrix and general condition of the skin investigated, due to morphological destruction during lesions' growth. A correlation between volunteers' age and the fluorescence spectra detected was observed during our measurements. Our next step is to increase developed initial database and to evaluate all sources of intrinsic fluorescent polarization effects and found if they are significantly altered from normal skin to cancerous state of the tissue, this way to develop a non-invasive diagnostic tool for dermatological practice.

  10. 78 FR 35658 - Spectra Energy Corp., Application for a New or Amended Presidential Permit

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-13

    ...DEPARTMENT OF STATE [Public Notice 8353] Spectra Energy Corp., Application for a New...State. ACTION: Notice of Receipt of Spectra Energy Corp., Application for a New...Department of State (DOS) has received from Spectra Energy Corp (``Spectra...

  11. Simulation of dielectric spectra of erythrocytes with various shapes

    NASA Astrophysics Data System (ADS)

    Asami, Koji

    2009-07-01

    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.

  12. Radial Distribution of Electron Spectra from High-Energy Ions

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.; Katz, Robert; Wilson, John W.

    1998-01-01

    The average track model describes the response of physical and biological systems using radial dose distribution as the key physical descriptor. We report on an extension of this model to describe the average distribution of electron spectra as a function of radial distance from an ion. We present calculations of these spectra for ions of identical linear energy transfer (LET), but dissimilar charge and velocity to evaluate the differences in electron spectra from these ions. To illustrate the usefulness of the radial electron spectra for describing effects that are not described by electron dose, we consider the evaluation of the indirect events in microdosimetric distributions for ions. We show that folding our average electron spectra model with experimentally determined frequency distributions for photons or electrons provides a good representation of radial event spectra from high-energy ions in 0.5-2 micrometer sites.

  13. Photoacoustic Spectra of Sm3 , Eu3 , Dy3 Complexes

    Microsoft Academic Search

    Zhang Yugeng

    1993-01-01

    The complexes crystals of Sm(Ac)3.4H2O, Eu(Ac)3.4H2O and a new complex Dy2(Ac)(NO3)4.12H2O were synthesized and their PA spectra were determined firstly. All their PA spectra absorptions are interpreted. The fluorescence properties of Sm, Eu, Dy and the relaxation process models were studied by their PA spectra.

  14. Theoretical study of W20+ spectra formation in EBIT plasma

    NASA Astrophysics Data System (ADS)

    Jonauskas, Valdas; Kynien?, Aušra; Kisielius, Romas; unas Masys, Šarbar

    2012-11-01

    Influence of the lowest levels of both the ground 4f8 configuration and first excited 4f75s configuration to formation of EBIT plasma spectra in the range 130 - 170 Å is studied. Analysis of continuum processes is performed in plane-wave Born and distorted wave approximations. These theoretical spectra were compared with spectra from collision radiative model that includes excitation (de-excitation) by electrons and radiative decay.

  15. Infrared spectra of formic acid clusters in noble gas matrices

    NASA Astrophysics Data System (ADS)

    Ito, Fumiyuki

    2015-07-01

    Infrared absorption spectra of formic acid clusters (HCOOH)n have been observed in noble gas matrices (Ar, Kr and Xe). The concentration dependence of the spectra and a comparison with the assigned monomeric/dimeric bands has led to the assignment of polymeric species (HCOOH)n (n > 2). From comparisons of these spectra with several sets of DFT calculations, we concluded that the observed polymeric species can be assigned to stable isomers of (HCOOH)3.

  16. Resonant Compton scattering and gamma-ray burst continuum spectra

    NASA Technical Reports Server (NTRS)

    Baring, M. G.

    1995-01-01

    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.

  17. Neutron Spectra and H*(10) in a 15 MV Linac

    SciTech Connect

    Benites, J. [Centro Estatal de Cancerologia de Nayarit-SSN-Mexico, Av. Enfermeria s/n, Col. Fray Junipero Serra, 63000 Tepic, Nayarit (Mexico); Alumno del Posgrado en CBAP, Universidad Autonoma de Nayarit, Carretera Tepic-Compostela km9. C.P. 63780. Xalisco-Nayarit-Mexico (Mexico); Vega-Carrillo, H. R.; Hernandez-Davila, V. M. [Unidad Academica de Estudios Nucleares, Universidad Autonoma de Zacatecas, Apdo. Postal 336, 98000 Zacatecas, Zac. Mexico (Mexico); Rivera, T. [CICATA-IPN, Unidad Legaria, Mexico city (Mexico); Carrillo, A.; Mondragon, R. [Centro Estatal de Cancerologia de Nayarit-SSN-Mexico, Av. Enfermeria s/n, Col. Fray Junipero Serra, 63000 Tepic, Nayarit (Mexico)

    2010-12-07

    Neutron spectra and the ambient dose equivalent were calculated inside the bunker of a 15 MV Varian linac model CLINAC iX. Calculations were carried out using Monte Carlo methods. Neutron spectra in the vicinity of isocentre show the presence of evaporation and knock-on neutrons produced by the source term, while epithermal and thermal neutron remain constant regardless the distance respect to isocentre, due to room return. Along the maze neutron spectra becomes softer as the detector moves along the maze. The ambient dose equivalent is decreased but do not follow the 1/r{sup 2} rule due to changes in the neutron spectra.

  18. Database-Driven Analyses of Astronomical Spectra

    NASA Astrophysics Data System (ADS)

    Cami, Jan

    2012-03-01

    Spectroscopy is one of the most powerful tools to study the physical properties and chemical composition of very diverse astrophysical environments. In principle, each nuclide has a unique set of spectral features; thus, establishing the presence of a specific material at astronomical distances requires no more than finding a laboratory spectrum of the right material that perfectly matches the astronomical observations. Once the presence of a substance is established, a careful analysis of the observational characteristics (wavelengths or frequencies, intensities, and line profiles) allows one to determine many physical parameters of the environment in which the substance resides, such as temperature, density, velocity, and so on. Because of this great diagnostic potential, ground-based and space-borne astronomical observatories often include instruments to carry out spectroscopic analyses of various celestial objects and events. Of particular interest is molecular spectroscopy at infrared wavelengths. From the spectroscopic point of view, molecules differ from atoms in their ability to vibrate and rotate, and quantum physics inevitably causes those motions to be quantized. The energies required to excite vibrations or rotations are such that vibrational transitions generally occur at infrared wavelengths, whereas pure rotational transitions typically occur at sub-mm wavelengths. Molecular vibration and rotation are coupled though, and thus at infrared wavelengths, one commonly observes a multitude of ro-vibrational transitions (see Figure 13.1). At lower spectral resolution, all transitions blend into one broad ro-vibrational molecular band. The isotope. Molecular spectroscopy thus allows us to see a difference of one neutron in an atomic nucleus that is located at astronomical distances! Since the detection of the first interstellar molecules (the CH [21] and CN [14] radicals), more than 150 species have been detected in space, ranging in size from diatomic species to the fullerene species C60 and C70 [4]. Given the large number and variety of molecules detected in space, molecular infrared spectroscopy can be used to study pretty much any astrophysical environment that is not too energetic to dissociate the molecules. At the lowest energies, it is interesting to note that molecules such as CN have been used to measure the temperature of the Cosmic Microwave Background (see e.g., Ref. 15). The great diagnostic potential of infrared molecular spectroscopy comes at a price though. Extracting the physical parameters from the observations requires expertise in knowing how various physical processes and instrumental characteristics play together in producing the observed spectra. In addition to the astronomical aspects, this often includes interpreting and understanding the limitations of laboratory data and quantum-chemical calculations; the study of the interaction of matter with radiation at microscopic scales (called radiative transfer, akin to ray tracing) and the effects of observing (e.g., smoothing and resampling) on the resulting spectra and possible instrumental effects (e.g., fringes). All this is not trivial. To make matters worse, observational spectra often contain many components, and might include spectral contributions stemming from very different physical conditions. Fully analyzing such observations is thus a time-consuming task that requires mastery of several techniques. And with ever-increasing rates of observational data acquisition, it seems clear that in the near future, some form of automation is required to handle the data stream. It is thus appealing to consider what part of such analyses could be done without too much human intervention. Two different aspects can be separated: the first step involves simply identifying the molecular species present in the observations. Once the molecular inventory is known, we can try to extract the physical parameters from the observed spectral properties. For both steps, good databases of molecular spectroscopic information is vital; the second step furthermor

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

    SciTech Connect

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

    2003-07-17

    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.

  20. Spitzer Spectra of Magellanic Cloud PNe

    E-print Network

    L. Stanghellini; P. Garcia Lario; A. Manchado; J. V. Perea Calderon; D. A. Garcia-Hernandez; R. A. Shaw; E. Villaver

    2006-05-30

    Planetary nebulae (PNe) in the Magellanic Clouds (LMC, SMC) offer a unique opportunity to study both the population and evolution of low- and intermediate-mass stars in an environment which is free of the distance scale bias that hinder Galactic PN studies. The emission shown by PNe in the 5-40 $\\mu$m range is characterized by the presence of a combination of solid state features (from the dust grains) and nebular emission lines over-imposed on a strong dust continuum. We acquired low resolution IRS spectroscopy of a selected sample of LMC and SMC PNe whose morphology, size, central star brightness, and chemical composition are known. The data have been acquired and reduced, and the IRS spectra show outstanding quality as well as very interesting features. The preliminary analysis presented here allows to determine strong correlations between gas and dust composition, and nebular morphology. More detailed analysis in the future will deepen our knowledge of mass-loss mechanism, its efficiency, and its relation to PN morphology.

  1. Synthetic infrared spectra for correlation spectroscopy

    SciTech Connect

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

    1997-12-01

    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.

  2. Characteristics of magnetospheric radio noise spectra

    NASA Technical Reports Server (NTRS)

    Herman, J. R.

    1976-01-01

    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 midfrequency range (100-1000 kHz) intense noise peaks rise 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. Bandwidths of the peaks range from about 100 kHz to more than 500 kHz; most often the lower cutoff is at about 100 kHz and the upper at 380 kHz for a total bandwidth of 280 kHz. This intense mid-frequency noise was detected at radial distances from 1.3 Re to 60 Re on all sides of the earth (i.e., all local times) 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.

  3. Resonance spectra of caged black holes

    E-print Network

    Shahar Hod

    2014-10-16

    Recent numerical studies of the coupled Einstein-Klein-Gordon system in a cavity have provided compelling evidence that {\\it 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-Nordstr\\"om black holes whose confining mirrors are placed in the near-horizon region $x_{\\text{m}}\\equiv (r_{\\text{m}}-r_+)/r_+\\ll\\tau\\equiv (r_+-r_-)/r_+$ (here $r_{\\text{m}}$ is the radius of the confining mirror and $r_{\\pm}$ 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: $\\omega_n=-i2\\pi T_{\\text{BH}}\\cdot n[1+O(x^n_{\\text{m}}/\\tau^n)]$, where $T_{\\text{BH}}$ is the temperature of the caged black hole and $n=1,2,3,...$ is the resonance parameter.

  4. Spectra as windows into exoplanet atmospheres

    PubMed Central

    Burrows, Adam S.

    2014-01-01

    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

  5. The Theory of Exoplanet Atmospheres and Spectra

    NASA Astrophysics Data System (ADS)

    Burrows, Adam S.

    2008-09-01

    Approximately 300 exoplanets, mostly giant planets (EGPs) in the Jovian mass range, have been detected orbiting stars in the solar neighborhood. More than 15% of them are transiting their primaries and these have collectively yielded a wealth of structural and physical information which theorists are scrambling to interpret. In this talk. I will present the current theory of the their atmospheres, compositions, and spectra. Due to stellar irradiation effects and heat redistribution by super-rotational jet streams, we must eventually construct with some fidelity 3D general circulation models (GCMs), with multi-D radiative transfer. However, simpler planar models with average irradiation boundary conditions and crude day-night heat transport algorithms do a reasonable 1st-order job of reproducing what is observed directly by the Spitzer infrared space telescope. In particular, thermal inversions and stratospheres are inferred for many close-in EGPs. I will discuss the confrontation of theory with data and summarize what has been learned to date.

  6. Cassini UVIS observations of Titan nightglow spectra

    NASA Astrophysics Data System (ADS)

    Ajello, Joseph M.; West, Robert A.; Gustin, Jacques; Larsen, Kristopher; Stewart, A. Ian F.; Esposito, Larry W.; McClintock, William E.; Holsclaw, Gregory M.; Bradley, E. Todd

    2012-12-01

    In this paper we present the first nightside EUV and FUV airglow limb spectra of Titan showing molecular emissions. The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed photon emissions of Titan's day and night limb-airglow and disk-airglow on multiple occasions, including during an eclipse observation. The 71 airglow observations analyzed in this paper show EUV (600-1150 Å) and FUV (1150-1900 Å) atomic multiplet lines and band emissions arising from either photoelectron induced fluorescence and solar photo-fragmentation of molecular nitrogen (N2) or excitation by magnetosphere plasma. The altitude of the peak UV emissions on the limb during daylight occurred inside the thermosphere at the altitude of the topside ionosphere (near 1000 km altitude). However, at night on the limb, a subset of emission features, much weaker in intensity, arise in the atmosphere with two different geometries. First, there is a twilight photoelectron-excited glow that persists with solar depression angle up to 25-30 degrees past the terminator, until the solar XUV shadow height passes the altitude of the topside ionosphere (1000-1200 km). The UV twilight glow spectrum is similar to the dayglow but weaker in intensity. Second, beyond 120° solar zenith angle, when the upper atmosphere of Titan is in total XUV darkness, there is indication of weak and sporadic nightside UV airglow emissions excited by magnetosphere plasma collisions with ambient thermosphere gas, with similar N2 excited features as above in the daylight or twilight glow over an extended altitude range.

  7. Extracting Quantitative Data from Lunar Soil Spectra

    NASA Technical Reports Server (NTRS)

    Noble, S. K.; Pieters, C. M.; Hiroi, T.

    2005-01-01

    Using the modified Gaussian model (MGM) developed by Sunshine et al. [1] we compared the spectral properties of the Lunar Soil Characterization Consortium (LSCC) suite of lunar soils [2,3] with their petrologic and chemical compositions to obtain quantitative data. Our initial work on Apollo 17 soils [4] suggested that useful compositional data could be elicited from high quality soil spectra. We are now able to expand upon those results with the full suite of LSCC soils that allows us to explore a much wider range of compositions and maturity states. The model is shown to be sensitive to pyroxene abundance and can evaluate the relative portion of high-Ca and low-Ca pyroxenes in the soils. In addition, the dataset has provided unexpected insights into the nature and causes of absorption bands in lunar soils. For example, it was found that two distinct absorption bands are required in the 1.2 m region of the spectrum. Neither of these bands can be attributed to plagioclase or agglutinates, but both appear to be largely due to pyroxene.

  8. [Fluorescence spectra of Dichroa febrifuga aqueous extraction].

    PubMed

    Zhang, Ying-hua; Shi, Xun-li; Liu, Ya-lan; Liu, Cui-ge; Wei, Yong-ju

    2007-02-01

    Fluorescence spectra of chang shan (Dichroa febrifuga Lour) aqueous extraction were studied. In the three-dimensional fluorescence contour spectrum, three fluorescence peaks of quinazoline alkaloids, which are the active components of chang shan, were observed. The excitation wavelengths of the peaks were 235, 270 and 320 nm, respectively, and the emission wavelength of all the peaks was 430 nm. Three-dimensional fluorescence contour spectrum is the very image of fingerprint, suitable for qualitative identification of traditional Chinese medicine. In the range of pH 3 to pH 6, the fluorescence spectrum of chang shan aqueous extractions changes with the variation in pH value. The reason for this spectral change might be the protonation of N-1 in quinazolone ring of beta-dichroine (febrifugine) molecule. There is an excellent linear relationship between the fluorescence intensity and the concentration of chang shan under nearly neutral conditions, thereby a quantitative method for the determination of quinazoline alkaloids may be established. PMID:17514972

  9. AIS spectra of desert shrub canopies

    NASA Technical Reports Server (NTRS)

    Murray, R.; Isaacson, D. L.; Schrumpf, B. J.; Ripple, W. J.; Lewis, A. J.

    1986-01-01

    Airborne Imaging Spectrometer (AIS) data were collected 30 August 1985 from a desert shrub community in central Oregon. Spectra from artificial targets placed on the test site and from bare soil, big sagebrush (Artemesia tridentata wyomingensis), silver sagebrush (Artemesia cana bolander), and exposed volcanic rocks were studied. Spectral data from grating position 3 (tree mode) were selected from 25 ground positions for analysis by Principal Factor Analysis (PFA). In this grating position, as many as six factors were identified as significant in contributing to spectral structure. Channels 74 through 84 (tree mode) best characterized between-class differences. Other channels were identified as nondiscriminating and as associated with such errors as excessive atmospheric absorption and grating positin changes. The test site was relatively simple with the two species (A. tridentata and A. cana) representing nearly 95% of biomass and with only two mineral backgrounds, a montmorillonitic soil and volcanic rocks. If, as in this study, six factors of spectral structure can be extracted from a single grating position from data acquired over a simple vegetation community, then AIS data must be considered rich in information-gathering potential.

  10. Electrical Analogues of Optical & EELS Spectra: Silicon

    NASA Astrophysics Data System (ADS)

    Smith, David Y.; Karstens, William

    2014-03-01

    We have explored an analogy between optical and electrical-circuit resonances that yields insight into single-particle and collective excitations. The analogy rests on the similarity of the differential equations for the Drude-Lorentz model of optics and the impedance of ac circuits. A parallel combination of capacitive (C) and inductive-capacitive (L-C) branches is a suitable circuit model. The L-C branches correspond to single-particle excitations. The C branch accounts for the electric-field term in the displacement, or equivalently the free-space susceptibility. Collective excitations represent combination resonances of the L-C and C branches. These excitations involve only internal mesh currents that can flow in the absence of an external (input) current. In this case, the admittance of the circuit is zero corresponding to the vanishing of the dielectric function at the plasmon resonance in optics (absent resistive losses). Circuit impedance corresponds to charged-particle energy loss. In contrast, circuit admittance (inverse impedance) corresponds to optical measurements. The interference of mesh currents in the circuit model plays the role of Coulomb screening in energy-loss spectra. Supported in part by the US Department of Energy, Office of Nuclear Physics under contract DE-AC02-06CH11357.

  11. Extreme value statistics for vibration spectra outlier Aurelien Hazana

    E-print Network

    Paris-Sud XI, Université de

    monitoring [4, 4.2], where a mask is built using healthy vibration data. However, this procedure laExtreme value statistics for vibration spectra outlier detection Aur´elien Hazana , J´egration, Villaroche Abstract The issue of detecting abnormal vibrations from spectra is tackled in this article, when

  12. Principal component analysis of International Ultraviolet Explorer galaxy spectra

    Microsoft Academic Search

    Liliana Formiggini; Noah Brosch

    2004-01-01

    We analyse the UV spectral energy distribution of a sample of normal galaxies listed in the International Ultraviolet Explorer (IUE) Newly Extracted Spectra (INES) Guide No. 2 - Normal Galaxies using a principal component analysis. The sample consists of the IUE short-wavelength (SW) spectra of the central regions of 118 galaxies, where the IUE aperture included more than 1 per

  13. Turn-over in pulsar spectra above 1 GHz

    E-print Network

    J. Kijak; Y. Gupta; K. Krzeszowski

    2007-01-09

    We present the first direct evidence for turn-over in pulsar radio spectra at high frequencies. Two pulsars are now shown to have a turn-over frequency > 1GHz. We also find some evidence that the peak frequency of turn-over in pulsar spectra appears to depend on dispersion measure and pulsar age.

  14. hal00276997, Raman spectra of misoriented bilayer graphene

    E-print Network

    Paris-Sud XI, Université de

    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

  15. An Artificial Neural Network Approach to Classification of Galaxy Spectra

    E-print Network

    S. R. Folkes; O. Lahav; S. J. Maddox

    1996-08-13

    We present a method for automated classification of galaxies with low signal-to-noise (S/N) spectra typical of redshift surveys. We develop spectral simulations based on the parameters for the 2dF Galaxy Redshift Survey, and with these simulations we investigate the technique of Principal Component Analysis when applied specifically to spectra of low S/N. We relate the objective principal components to features in the spectra and use a small number of components to successfully reconstruct the underlying signal from the low quality spectra. Using the principal components as input, we train an Artificial Neural Network to classify the noisy simulated spectra into morphological classes, revealing the success of the classification against the observed $b_{\\rm J}$ magnitude of the source, which we compare with alternative methods of classification. We find that more than 90\\% of our sample of normal galaxies are correctly classified into one of five broad morphological classes for simulations at $b_{\\rm J}$=19.7. By dividing the data into separate sets we show that a classification onto the Hubble sequence is only relevant for normal galaxies and that spectra with unusual features should be incorporated into a classification scheme based predominantly on their spectral signatures. We discuss how an Artificial Neural Network can be used to distinguish normal and unusual galaxy spectra, and discuss the possible application of these results to spectra from galaxy redshift surveys.

  16. Electronic absorption spectra of heterocyclic analogs of trans-chalcone

    Microsoft Academic Search

    M. Reinkhardt; A. A. Sukhorukov; V. F. Lavrushin

    1977-01-01

    Thiophene, furan, and pyrrole analogs of trans-chalcone have UV spectra consisting of bands belonging to the spectra of the corresponding 2-acetylhetaryls and 2-hetarylideneacetones that are shifted bathochromically as a result of mutual perturbation of these two crossconjugated fragments. The absorption curves of 10 chalcones in hexane solution were measured up to 190 nm, the bands of the individual transitions were

  17. Rotational relaxation of rigid dipolar molecules in nonlinear dielectric spectra

    Microsoft Academic Search

    Kurt de Smet; Louis Hellemans; J. F. Rouleau; R. Courteau; T. K. Bose

    1998-01-01

    We present complete nonlinear dielectric spectra for a rigid dipolar molecule in dilute solution. The spectra are described theoretically by dispersions of the form as predicted by Coffey and Paranjape [Proc. R. Ir. Acad. 78, 17 (1978)] and by Alexiewicz and Kasprowicz-Kielich [Modern Nonlinear Optics, edited by M. Evans and S. Kielich (Wiley, New York, 1993), Vol. 85, pt. 1,

  18. On the structure of water NMR spectra in membranes

    NASA Astrophysics Data System (ADS)

    Mank, V. V.; Lebovka, N. I.; Dumanski, A. V.

    1983-04-01

    Proton magnetic resonance spectra of water in magnetically non-uniform heterogeneous systems is analysed. It is shown that the multiple structure of spectra for different heterogeneous objects, including membranes, may be determined by the effects of magnetic inhomogeneity providing the ordered distribution for water-filled pores of anisotropic form exists.

  19. Doppler Spectra and Estimated Windspeed of a Violent Tornado

    Microsoft Academic Search

    Dusan Zrni; Donald W. Burgess; Larry Hennington

    1985-01-01

    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

  20. Ionospheric Sensitivity to Different Representations of EUV Spectra

    Microsoft Academic Search

    C. Smithtro; J. J. Sojka; J. Lean; R. W. Schunk

    2002-01-01

    It is well established that solar EUV radiation is responsible for the formation of the ionosphere, and in lieu of continuous direct observations, there exist a number of different models of this spectra. Empirical models have been developed from parameterized fits of past rocket and satellite measurements, while the newly developed NRLEUV model computes the spectra by accounting for the

  1. Theoretical Spectra and Atmospheres of Extrasolar Giant Planets

    Microsoft Academic Search

    David Sudarsky; Adam Burrows; Ivan Hubeny

    2003-01-01

    We present a comprehensive theory of the spectra and atmospheres of irradiated extrasolar giant planets. We explore the dependences on stellar type, orbital distance, cloud characteristics, planet mass, and surface gravity. Phase-averaged spectra for specific known extrasolar giant planets that span a wide range of the relevant parameters are calculated, plotted, and discussed. The connection between atmospheric composition and emergent

  2. Vibrational spectra of the two hydrates of strontium oxalate.

    PubMed

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

    2015-02-25

    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

  3. Spectra of heavy-light mesons at finite temperature

    E-print Network

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

    2009-09-13

    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.

  4. Boson spectra and correlations for thermal locally equilibrium systems

    Microsoft Academic Search

    Yu. M. Sinyukov

    1999-01-01

    The single- and multi- particle inclusive spectra for strongly inhomogeneous thermal boson systems are studied using the method of statistical operator. The thermal Wick's theorem is generalized and the analytical solution of the problem for an boost-invariant expanding boson gas is found. The results demonstrate the effects of inhomogeneity for such a system: the spectra and correlations for particles with

  5. Raman spectra and optical coherent tomography images of skin

    Microsoft Academic Search

    A. E. Villanueva-Luna; J. Castro-Ramos; S. Vazquez-Montiel; A. Flores-Gil; J. A. Delgado-Atencio; A. Vazquez-Villa

    2011-01-01

    The optical coherence tomography images are useful to see the internal profile and the structure of material samples. In this work, OCT images were recorded in 10 volunteers with different skin tone which were related to Raman spectra. The areas where we obtained OCT images and Raman spectra were a) index finger nail, b) between index finger and middle finger,

  6. Broadband proton-decoupled proton spectra Andrew J. Pell

    E-print Network

    Keeler, James

    Broadband proton-decoupled proton spectra Andrew J. Pell , Richard A. E. Edden§ and James Keeler.ac.uk. #12;Abstract We present a new method for recording broadband proton-decoupled proton spectra with ab reduction in sensitivity when com- pared to a conventional proton spectrum. The method is demonstrated

  7. Apollo 16 far ultraviolet spectra of the terrestrial airglow

    Microsoft Academic Search

    G. R. Carruthers; Thornton Page

    1976-01-01

    Far ultraviolet spectra of the terrestrial airglow were obtained from the lunar surface during the Apollo 16 mission. The spectra cover the wavelength range 490-1600 A with a resolution of about 40 A and the wavelength range 1050-1600 A with a resolution of 30 A. Features recorded spectrographically for the first time include He 584 A, O(+) 834 A, H

  8. Relating reflectance spectra space to Munsell color appearance space

    Microsoft Academic Search

    A. Kimball Romney

    2008-01-01

    The goal is to construct a simple model relating the conceptually defined Munsell color space to a physical representation of the relationship among the reflectance spectra obtained from the color chips comprising the Munsell color atlas. In the model both the Munsell conceptual system and the transformed reflectance spectra are shown to be well represented in Euclidean space, and the

  9. Modal Spectra Seismic Analysis for non-uniform excitation

    SciTech Connect

    Vashi, K.M.

    1990-12-31

    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.

  10. Modal Spectra Seismic Analysis for non-uniform excitation

    SciTech Connect

    Vashi, K.M.

    1990-01-01

    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.

  11. Computational model of human skin for reflected spectra simulation

    Microsoft Academic Search

    Igor V. Meglinsky; Stephen J. Matcher

    2000-01-01

    Obtaining quantified measurements of oxygen saturation of skin blood from collected diffuse reflectance spectra is complicated by the fact that blood and pigments are not distributed in skin tissues homogeneously. Using the developed Monte Carlo technique and simple multi-layered model of skin we have simulated the reflection skin spectra. The computational model contains seven layers with rough boundary surfaces. Absorption

  12. Spectra of neutrons from a beam-driven fusion source

    NASA Astrophysics Data System (ADS)

    Goncharov, P. R.

    2015-06-01

    Semianalytical calculations of fusion neutron spectra in case of the presence of substantial suprathermal tails in fuel nuclei velocity distributions have been implemented using two different approaches. Numerical techniques are described. Results for a variety of isotropic and anisotropic distributions of suprathermal fuel nuclei are presented. Verification of calculated fusion product spectra has been performed using several methods.

  13. An investigation of a mathematical model for atmospheric absorption spectra

    NASA Technical Reports Server (NTRS)

    Niple, E. R.

    1979-01-01

    A computer program that calculates absorption spectra for slant paths through the atmosphere is described. The program uses an efficient convolution technique (Romberg integration) to simulate instrument resolution effects. A brief information analysis is performed on a set of calculated spectra to illustrate how such techniques may be used to explore the quality of the information in a spectrum.

  14. Measurement of inclusive neutron spectra at the ISR

    Microsoft Academic Search

    J. Engler; B. Gibbard; W. Isenbeck; F. Moennig; J. Moritz; K. Pack; K. H. Schmidt; D. Wegener; W. Bartel; W. Flauger; H. Schopper

    1975-01-01

    With a total absorption counter, inclusive neutron spectra have been measured at four ISR energies and at angles of 20, 66 and 119 mrad. The spectra show scaling behavior in the variables x and p?. Pion exchange is found to be important at large x values.

  15. TOPSAR wave spectra model and coastal erosion detection

    Microsoft Academic Search

    Maged Mahmoud Marghany

    2001-01-01

    This paper presents work done utilizing TOPSAR data to detect shoreline change along the Terengganu coast (Malaysia). TOPSAR data were used to extract information on wave spectra. This wave spectra information was then used to model shoreline changes by investigating the wave refraction patterns. From these patterns, the volume transport at several locations was estimated. The shoreline change model developed

  16. Molecular Spectra of Sulfur Molecules and Solid Sulfur Allotropes

    Microsoft Academic Search

    Bodo Eckert; Ralf Steudel

    Molecular spectroscopy is one of the most important means to characterize the various species in solid, liquid and gaseous elemental sulfur. In this chapter the vibrational, UV-Vis and mass spectra of sulfur molecules with between 2 and 20 atoms are critically reviewed together with the spectra of liquid sulfur and of solid allotropes including polymeric and high-pressure phases. In particular,

  17. A comparative study of using in-line near-infrared spectra, ultraviolet spectra and fused spectra to monitor Panax notoginseng adsorption process.

    PubMed

    Jiang, Cheng; Qu, Haibin

    2015-01-01

    The step of enriching and purifying saponins by macroporous resin column chromatography is closely related to the safety and efficacy of Panax notoginseng products during their manufacturing processes. Adsorption process is one of the most critical unit operations within each chromatographic cycle. In order to understand the adsorption process directly, it is necessary to develop a rapid and precise method to monitor the adsorption process in real time. In this study, comparative evaluation of using near-infrared (NIR) spectra, ultraviolet (UV) spectra and fused spectra to monitor the adsorption process of P. notoginseng was conducted. The uninformative variable elimination by partial least squares (UVE-PLS) regression models were established for quantification of notoginsenoside R1, ginsenoside Rg1, ginsenoside Re, ginsenoside Rb1 and ginsenoside Rd in effluents based on different spectra. There was a significant improvement provided by the models based on fused spectra. The results in this work were conducive to solving the problems about real-time quantitative analysis of saponins during P. notoginseng adsorption. The fusion method of NIR and UV spectra combined with UVE-PLS regression could be a promising strategy to real-time analyze the components, which are difficult to be quantified by individual spectroscopic technique. PMID:25255448

  18. The first observation of Carbon-13 spin noise spectra

    PubMed Central

    Schlagnitweit, Judith; Müller, Norbert

    2012-01-01

    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

  19. The first observation of Carbon-13 spin noise spectra.

    PubMed

    Schlagnitweit, Judith; Müller, Norbert

    2012-11-01

    We demonstrate the first (13)C 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 (13)C enriched methanol and glycerol samples at 176 MHz without and with (1)H decoupling, which increases the sensitivity without introducing radio frequency interference with the weak spin noise. The multiplet amplitude ratios in (1)H 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 (1)H-decoupled (13)C spin noise spectra. PMID:23041799

  20. FULL POLARIZATION SPECTRA OF 3C 279

    SciTech Connect

    Homan, D. C. [Department of Physics and Astronomy, Denison University, 1 Main Street, Granville, OH 43023 (United States); Lister, M. L. [Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907 (United States); Aller, H. D.; Aller, M. F. [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States); Wardle, J. F. C. [Department of Physics, Brandeis University, Waltham, MA 02454 (United States)], E-mail: homand@denison.edu, E-mail: mlister@physics.purdue.edu, E-mail: haller@umich.edu, E-mail: mfa@umich.edu, E-mail: wardle@brandeis.edu

    2009-05-01

    We report the results of parsec-scale, multifrequency Very Long Baseline Array observations of the core region of 3C 279 in Stokes I, linear polarization, and circular polarization. These full polarization spectra are modeled by radiative transfer simulations to constrain the magnetic field and particle properties of the parsec-scale jet in 3C 279. We find that the polarization properties of the core region, including the amount of linear polarization, the amount and sign of Faraday rotation, and the amount and sign of circular polarization can be explained by a consistent physical picture. The base of the jet, component D, is modeled as an inhomogeneous Blandford-Koenigl style conical jet dominated by a vector-ordered poloidal magnetic field along the jet axis, and we estimate its net magnetic flux. This poloidal field is responsible for the linear and circular polarization from this inhomogeneous component. Farther down the jet, the magnetic field in two homogeneous features is dominated by local shocks and a smaller fraction of vector-ordered poloidal field remains along the jet axis. This remaining poloidal field provides internal Faraday rotation which drives Faraday conversion of linear polarization into circular polarization from these components. In this picture, we find the jet to be kinetically dominated by protons with the radiating particles being dominated by electrons at an approximate fraction of {approx}>75%, still allowing the potential for a significant admixture of positrons. Based on the amounts of Faraday conversion deduced for the homogeneous components, we find a plausible range for the lower cutoff in the relativistic particle energy spectrum to be 5 {approx}< {gamma} {sub l} {approx}< 35. The physical picture described here is not unique if the observed Faraday rotation and depolarization occur in screens external to the jet; however, we find the joint explanation of linear and circular polarization observations from a single set of magnetic fields and particle properties internal to the jet to be compelling evidence for this picture.

  1. HOT ELECTROMAGNETIC OUTFLOWS. I. ACCELERATION AND SPECTRA

    SciTech Connect

    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

    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.

  2. A rotating string model versus baryon spectra

    E-print Network

    Jacob Sonnenschein; Dorin Weissman

    2015-01-01

    We continue our program of describing hadrons as rotating strings with massive endpoints. In this paper we propose models of baryons and confront them with the baryon Regge trajectories. We show that these are best fitted by a model of a single string with a quark at one endpoint and a diquark at the other. This model is preferred over the Y-shaped string model with a quark at each endpoint. We show how the model follows from a stringy model of the holographic baryon which includes a baryonic vertex connected with N_c strings to flavor probe branes. From fitting to baryonic data we find that there is no clear evidence for a non-zero baryonic vertex mass, but if there is such a mass it should be located at one of the string endpoints. The available baryon trajectories in the angular momentum plane (J,M^2), involving light, strange, and charmed baryons, are rather well fitted when adding masses to the string endpoints, with a single universal slope of 0.95 GeV^-2. Most of the results for the quark masses are then found to be consistent with the results extracted from the meson spectra in a preceding paper, where the value of the slope emerging from the meson fits was found to be 0.90 GeV^-2. In the plane of quantum radial excitations, (n,M^2), we also find a good agreement between the meson and baryon slopes. The flavor structure of the diquark is examined, where our interest lies in particular on baryons composed of more than one quark heavier than the u and d quarks. For these baryons we present a method of checking the holographic interpretation of our results.

  3. Near infrared spectra of the Orion bar

    NASA Astrophysics Data System (ADS)

    Marconi, A.; Testi, L.; Natta, A.; Walmsley, C. M.

    1998-02-01

    We have used the LONGSP spectrometer on the 1.5-m TIRGO telescope to obtain long slit spectra in the J, H, and K wavelength bands towards two positions along the Orion bar. These data have been supplemented with images made using the ARNICA camera mounted on TIRGO as well as with an ESO NTT observation carried out by Dr A. Moorwood. We detect a variety of transitions of hydrogen, helium, OI, FeII, FeIII, and H_2. From our molecular hydrogen data, we conclude that densities are moderate (3-6x 10(4) cm(-3) ) in the layer responsible for the molecular hydrogen emission and give no evidence for the presence of dense neutral clumps. We also find that the molecular hydrogen bar is likely to be tilted by ~ 10 degrees relative to the line of sight. We discuss the relative merits of several models of the structure of the bar and conclude that it may be split into two structures separated by 0.2-0.3 parsec along the line of sight. It also seems likely to us that in both structures, density increases along a line perpendicular to the ionization front which penetrates into the neutral gas. We have used the 1.317mum OI line to estimate the FUV radiation field incident at the ionization front and find values of 1-3x 10(4) greater than the average interstellar field. From [FeII] line measurements, we conclude that the electron density in the ionized layer associated with the ionization front is of order 10(4) \\percc. Finally, our analysis of the helium and hydrogen recombination lines implies essential coincidence of the helium and hydrogen Stromgren spheres.

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

    USGS Publications Warehouse

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

    1995-01-01

    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

  5. Spectra of hadrons and muons in the atmosphere: primary spectra, characteristics of hadron-air interactions

    E-print Network

    A. V. Yushkov; A. A. Lagutin

    2006-12-01

    Self-consistency of interaction models QGSJET 01, SIBYLL 2.1, NEXUS 3.97 and QGSJET II is checked in terms of their ability to reproduce simultaneously experimental data on fluxes of muons and hadrons. From this point of view SIBYLL 2.1 gives the most acceptable, though not quite satisfactory, results. Analysis of the situation for muons supports our previous conclusions, that high-energy muon deficit is due both to underestimation of primary light nuclei fluxes in direct emulsion chamber experiments and to softness of $p+A\\to\\pi^\\pm,K^\\pm+X$ inclusive spectra in fragmentation region, especially prominent in case of QGSJET 01 model.

  6. About the Reference AM 1.5 Spectra American Society for Testing and Materials (ASTM) Terrestrial Reference Spectra

    E-print Network

    Chen, C. Julian

    About the Reference AM 1.5 Spectra American Society for Testing and Materials (ASTM) Terrestrial with the American Society for Testing and Materials (ASTM) (http://www.astm.org/) and government research, ASTM G-173-03. HISTORICAL NOTE : The reference spectra were first generated as separate standards

  7. The angular power spectra of polarized Galactic synchrotron

    E-print Network

    M. Tucci; E. Carretti; S. Cecchini; R. Fabbri; M. Orsini; E. Pierpaoli

    2000-06-27

    We derive the angular power spectra of intensity and polarization of Galactic synchrotron emission in the range 36 < l < 10^3 from the Parkes survey mapping the southern Galactic plane at 2.4 GHz. The polarization spectra of both electric and magnetic parity up to l \\simeq 10^3 are approximated very well by power laws with slope coefficients \\simeq 1.4, quite different from the CMB spectra. We show that no problem should arise from Galactic synchrotron for measurements of CMB polarization in the cosmological window.

  8. Temperature dependence of the solvated electron absorption spectra in propanediols

    NASA Astrophysics Data System (ADS)

    Lampre, I.; Lin, M.; He, H.; Han, Z.; Mostafavi, M.; Katsumura, Y.

    2005-01-01

    Using nanosecond pulse radiolysis, the absorption spectra of the solvated electron have been recorded at different temperatures from 295 to 498 K in 1,2-propanediol (12PD) and 1,3-propanediol (13PD). In both solvents, the optical spectra shift to the red with increasing temperature. While the shape of the spectra does not change in 13PD, a widening on the blue side of the absorption band is observed in 12PD by increasing the temperature from 296 to 473 K.

  9. Spectra of Husimi cacti: exact results and applications.

    PubMed

    Galiceanu, Mircea; Blumen, Alexander

    2007-10-01

    Starting from exact relations for finite Husimi cacti we determine their complete spectra to very high accuracy. The Husimi cacti are dual structures to the dendrimers but, distinct from these, contain loops. Our solution makes use of a judicious analysis of the normal modes. Although close to those of dendrimers, the spectra of Husimi cacti differ. From the wealth of applications for measurable quantities which depend only on the spectra, we display for Husimi cacti the behavior of the fluorescence depolarization under quasiresonant Forster energy transfer. PMID:17919051

  10. SIMULATING LARGE-SCALE STRUCTURE FORMATION FOR BSI POWER SPECTRA

    E-print Network

    V. Mueller

    1995-05-30

    A double inflationary model provides perturbation spectra with enhanced power at large scales (Broken Scale Invariant perturbations -- BSI), leading to a promising scenario for the formation of cosmic structures. We describe a series of high-resolution PM simulations with a model for the thermodynamic evolution of baryons in which we are capable of identifying 'galaxy' halos with a reasonable mass spectrum and following the genesis of large and super-large scale structures. The power spectra and correlation functions of 'galaxies' are compared with reconstructed power spectra of the CfA catalogue and the correlation functions of the Las Campanas Deep Redshift Survey.

  11. Analyzer of Spectra for Age Determination (ASAD) - Algorithm and Applications

    E-print Network

    Asa'd, Randa

    2014-01-01

    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.

  12. Computer Processing Of Tunable-Diode-Laser Spectra

    NASA Technical Reports Server (NTRS)

    May, Randy D.

    1991-01-01

    Tunable-diode-laser spectrometer measuring transmission spectrum of gas operates under control of computer, which also processes measurement data. Measurements in three channels processed into spectra. Computer controls current supplied to tunable diode laser, stepping it through small increments of wavelength while processing spectral measurements at each step. Program includes library of routines for general manipulation and plotting of spectra, least-squares fitting of direct-transmission and harmonic-absorption spectra, and deconvolution for determination of laser linewidth and for removal of instrumental broadening of spectral lines.

  13. Diagnosis gynecological tumors based on urine first derivative spectra

    NASA Astrophysics Data System (ADS)

    Gao, Shumei; Jun, Lu; Chen, Guoqing

    2010-11-01

    We investigate the use of first derivative intrinsic fluorescence spectroscopy as an adjunctive tool for early diagnosis or screening on gynecological tumors. The first derivative intrinsic fluorescence spectra from limosis morning urine of gynecologic cancerous patient and the healthy group are measured. And Combining the first order derivative spectra method and clinic diagnosis standard to cluster analysis the information, we obtained that the diagnostic sensitivity and specificity are 81% and 75% based on the judgment of setting ?=300, respectively. It may be applied to early diagnose gynecological tumors using intrinsic urine fluorescence spectra.

  14. Stretched-exponential Doppler spectra in underwater acoustic communication channels.

    PubMed

    van Walree, P A; Jenserud, T; Otnes, R

    2010-11-01

    The theory of underwater sound interacting with the sea surface predicts a Gaussian-spread frequency spectrum in the case of a large Rayleigh parameter. However, recent channel soundings reveal more sharply peaked spectra with heavier tails. The measured Doppler spread increases with the frequency and differs between multipath arrivals. The overall Doppler spectrum of a broadband waveform is the sum of the spectra of all constituent paths and frequencies, and is phenomenologically described by a stretched or compressed exponential. The stretched exponential also fits well to the broadband spectrum of a single propagation path, and narrowband spectra summed over all paths. PMID:21110547

  15. The analysis of spectra of novae taken near maximum

    NASA Technical Reports Server (NTRS)

    Stryker, L. L.; Hestand, J.; Starrfield, S.; Wehrse, R.; Hauschildt, P.; Spies, W.; Baschek, B.; Shaviv, G.

    1988-01-01

    A project to analyze ultraviolet spectra of novae obtained at or near maximum optical light is presented. These spectra are characterized by a relatively cool continuum with superimposed permitted emission lines from ions such as Fe II, Mg II, and Si II. Spectra obtained late in the outburst show only emission lines from highly ionized species and in many cases these are forbidden lines. The ultraviolet data will be used with calculations of spherical, expanding, stellar atmospheres for novae to determine elemental abundances by spectral line synthesis. This method is extremely sensitive to the abundances and completely independent of the nebular analyses usually used to obtain novae abundances.

  16. Improved Quantitative Analysis of Spectra Using a New Method of Obtaining Derivative Spectra Based on a Singular Perturbation Technique.

    PubMed

    Li, Zhigang; Wang, Qiaoyun; Lv, Jiangtao; Ma, Zhenhe; Yang, Linjuan

    2015-06-01

    Spectroscopy is often applied when a rapid quantitative analysis is required, but one challenge is the translation of raw spectra into a final analysis. Derivative spectra are often used as a preliminary preprocessing step to resolve overlapping signals, enhance signal properties, and suppress unwanted spectral features that arise due to non-ideal instrument and sample properties. In this study, to improve quantitative analysis of near-infrared spectra, derivatives of noisy raw spectral data need to be estimated with high accuracy. A new spectral estimator based on singular perturbation technique, called the singular perturbation spectra estimator (SPSE), is presented, and the stability analysis of the estimator is given. Theoretical analysis and simulation experimental results confirm that the derivatives can be estimated with high accuracy using this estimator. Furthermore, the effectiveness of the estimator for processing noisy infrared spectra is evaluated using the analysis of beer spectra. The derivative spectra of the beer and the marzipan are used to build the calibration model using partial least squares (PLS) modeling. The results show that the PLS based on the new estimator can achieve better performance compared with the Savitzky-Golay algorithm and can serve as an alternative choice for quantitative analytical applications. PMID:25954978

  17. Necessary conditions for a maximum likelihood estimate to become asymptotically unbiased and attain the Cramer-Rao lower bound. II. Range and depth localization of a sound source in an ocean waveguide.

    PubMed

    Thode, Aaron; Zanolin, Michele; Naftali, Eran; Ingram, Ian; Ratilal, Purnima; Makris, Nicholas C

    2002-11-01

    Analytic expressions for the first order bias and second order covariance of a maximum-likelihood estimate (MLE) are applied to the problem of localizing an acoustic source in range and depth in a shallow water waveguide with a vertical hydrophone array. These expressions are then used to determine necessary conditions on sample size, or equivalently signal-to-noise ratio (SNR), for the localization MLE to become asymptotically unbiased and attain minimum variance as expressed by the Cramer-Rao lower bound (CRLB). These analytic expressions can be applied in a similar fashion to any ocean-acoustic inverse problem involving random data. Both deterministic and completely randomized signals embedded in independent and additive waveguide noise are investigated. As the energy ratio of received signal to additive noise (SANR) descends to the lower operational range of a typical passive localization system, source range and depth estimates exhibit significant biases and have variances that can exceed the CRLB by orders of magnitude. The spatial structure of the bias suggests that acoustic range and depth estimates tend to converge around particular range and depth cells for moderate SANR values. PMID:12430801

  18. Linear discriminant analysis of brain tumour (1)H MR spectra: a comparison of classification using whole spectra versus metabolite quantification.

    PubMed

    Opstad, K S; Ladroue, C; Bell, B A; Griffiths, J R; Howe, F A

    2007-12-01

    (1)H MRS is an attractive choice for non-invasively diagnosing brain tumours. Many studies have been performed to create an objective decision support system, but there is not yet a consensus as to the best techniques of MRS acquisition or data processing to be used for optimum classification. In this study, we investigate whether LCModel analysis of short-TE (30 ms), single-voxel tumour spectra provide a better input for classification than the use of the original spectra. A total of 145 histologically diagnosed brain tumour spectra were acquired [14 astrocytoma grade II (AS2), 15 astrocytoma grade III (AS3), 42 glioblastoma (GBM), 41 metastases (MET) and 33 meningioma (MNG)], and linear discriminant analyses (LDA) were performed on the LCModel analysis of the spectra and the original spectra. The results consistently suggest improvement in classification when the LCModel concentrations are used. LDA of AS2, MNG and high-grade tumours (HG, comprising GBM and MET) correctly classified 94% using the LCModel dataset compared with 93% using the spectral dataset. The inclusion of AS3 reduced the accuracy to 82% and 78% for LCModel analysis and the original spectra, respectively, and further separating HG into GBM and MET gave 70% compared with 60%. Generally MNG spectra have profiles that are visually distinct from those of the other tumour types, but the classification accuracy was typically about 80%, with MNG with substantial lipid/macromolecule signals being classified as HG. Omission of the lipid/macromolecule concentrations in the LCModel dataset provided an improvement in classification of MNG (91% compared with 76%). In conclusion, there appears to be an advantage to performing pattern recognition on the quantitative analysis of tumour spectra rather than using the whole spectra. However, the results suggest that a two-step LDA process may help in classifying the five tumour groups to provide optimum classification of MNG with high lipid/macromolecule contributions which maybe misclassified as HG. PMID:17326043

  19. Reconstruction of continuous spectra by the regularization method using model spectra

    NASA Astrophysics Data System (ADS)

    Sizikov, V. S.; Krivykh, A. V.

    2014-12-01

    The inverse problem of spectroscopy—reconstruction of continuous spectra by solving the Fredholm integral equation of the first kind (an ill-posed problem)—is considered. The equation is solved by the Tikhonov regularization method using the method of computational experiments, according to which, along with initial example P, where experimental spectrum u is specified and true spectrum z is sought for, "similar" model example spectrum Q (or several examples) with specified z and modeled u is processed with allowance for additional information on true spectrum z in example P. This approach makes it possible to choose regularization parameter ? and estimate the error in reconstructing spectrum z in example P. Some numerical illustrations are presented. Different response functions of spectrometers are considered: slotlike, triangular, diffraction, Gaussian, dispersion, and exponential; identical widths a(?) at a level of 0.5 and identical integral widths W(?) are used.

  20. Atomistic modeling of IR action spectra under circularly polarized electromagnetic fields: toward action VCD spectra.

    PubMed

    Calvo, Florent

    2015-03-01

    The nonlinear response and dissociation propensity of an isolated chiral molecule, camphor, to a circularly polarized infrared laser pulse was simulated by molecular dynamics as a function of the excitation wavelength. The results indicate similarities with linear absorption spectra, but also differences that are ascribable to dynamical anharmonic effects. Comparing the responses between left- and right-circularly polarized pulses in terms of dissociation probabilities, or equivalently between R- and S-camphor to a similarly polarized pulse, we find significant differences for the fingerprint C?=?O amide mode, with a sensitivity that could be sufficient to possibly enable vibrational circular dichroism as an action technique for probing molecular chirality and absolute conformations in the gas phase. PMID:25689775

  1. Simulation of the Raman spectra of CO?: bridging the gap between algebraic models and experimental spectra.

    PubMed

    Lemus, R; Sánchez-Castellanos, M; Pérez-Bernal, F; Fernández, J M; Carvajal, M

    2014-08-01

    The carbon dioxide Raman spectrum is simulated within an algebraic approach based on curvilinear coordinates in a local representation. The two main advantages of the present algebraic approach are a possible connection with configuration space and the correct description of systems with either local or normal mode character. The system Hamiltonian and polarizability tensor are expanded in terms of curvilinear coordinates. The curvilinear coordinates are in turn expanded into normal coordinates, obtaining an algebraic representation in terms of normal bosonic operators. A canonical transformation maps the operators into a local algebraic representation. The final step is an anharmonization procedure to local operators. The Raman spectrum of CO2 has been simulated, obtaining results close to experimental accuracy, and polarizability transition moments for the Raman spectral lines between 1150 cm(-1) and 1500 cm(-1) are reported. The comparison between experimental and simulated spectra has provided six new CO2 experimental vibrational terms. PMID:25106586

  2. A New Extensive Library of Synthetic Stellar Spectra from PHOENIX Atmospheres and its Application to Fitting VLT MUSE Spectra

    E-print Network

    Husser, T -O; Dreizler, S; Hauschildt, Peter H

    2012-01-01

    We present a new library of synthetic spectra based on the stellar atmosphere code PHOENIX. It covers the wavelength range from 500{\\AA} to 55000{\\AA} with a resolution of R=500000 in the optical and near IR, R=100000 in the IR and {\\Delta}{\\lambda}=0.1{\\AA} in the UV. The parameter space covers 2300Ksynthetic spectra will be available for download. Futhermore we present a method for fitting spectra, especially designed to work with the new 2nd generation VLT instrument MUSE. We show that we can determine stellar parameters (Teff, log(g), [Fe/H] and [{\\alpha}/Fe]) and even single element abundances.

  3. Strings, Waves, Drums: Spectra and Inverse Richard Beals

    E-print Network

    Strings, Waves, Drums: Spectra and Inverse Problems Richard Beals Yale University Peter C. Greiner one hear the shape of a drum? 51 13 Inverting an elliptic operator 57 14 Indices and index theorems 63

  4. On the Emergent Spectra of Hot Protoplanet Collision Afterglows

    E-print Network

    Miller-Ricci, Eliza

    We explore the appearance of terrestrial planets in formation by studying the emergent spectra of hot molten protoplanets during their collisional formation. While such collisions are rare, the surfaces of these bodies may ...

  5. Far-infrared reflectance spectra of optical black coatings

    NASA Technical Reports Server (NTRS)

    Smith, S. M.

    1983-01-01

    Far-infrared specular reflectance spectra of six optically black coatings near normal incidence are presented. The spectra were obtained using nine bandpass transmission filters in the wavelength range between 12 and 300 microns. Data on the construction, thickness, and rms surface roughness of the coatings are also presented. The chemical composition of two coatings can be distinguished from that of the others by a strong absorption feature between 20 and 40 microns which is attributed to amorphous silicate material. Inverse relationships between these spectra and coating roughness and thickness are noted and lead to development of a reflecting-layer model for the measured reflectance. The model is applied to the spectra of several coatings whose construction falls within its constraints.

  6. Infrared spectra of olivine polymorphs - Alpha, beta phase and spinel

    NASA Technical Reports Server (NTRS)

    Jeanloz, R.

    1980-01-01

    The infrared absorption spectra of several olivines (alpha phase) and their corresponding beta phase (modified spinel) and spinel (gamma) high-pressure polymorphs are determined. Spectra were measured for ground and pressed samples of alpha and gamma A2SiO4, where A = Fe, Ni, Co; alpha and gamma Mg2GeO4; alpha Mg2SiO4; and beta Co2SiO4. The spectra are interpreted in terms of internal, tetrahedral and octagonal, and lattice vibration modes, and the spinel results are used to predict the spectrum of gamma Mg2SiO4. Analysis of spectra obtained from samples of gamma Mg2GeO4 heated to 730 and 1000 C provides evidence that partial inversion could occur in silicate spinels at elevated temperatures and pressures.

  7. UV spectra of benzene isotopomers and dimers in helium nanodroplets

    NASA Astrophysics Data System (ADS)

    Schmied, Roman; ?arçabal, Pierre; Dokter, Adriaan M.; Lonij, Vincent P. A.; Lehmann, Kevin K.; Scoles, Giacinto

    2004-08-01

    We report spectra of various benzene isotopomers and their dimers in helium nanodroplets in the region of the first Herzberg-Teller allowed vibronic transition 601 1B2u?1A1g (the A00 transition) at ˜260 nm. Excitation spectra have been recorded using both beam depletion detection and laser-induced fluorescence. Unlike for many larger aromatic molecules, the monomer spectra consist of a single "zero-phonon" line, blueshifted by ˜30 cm-1 from the gas phase position. Rotational band simulations show that the moments of inertia of C6H6 in the nanodroplets are at least six-times larger than in the gas phase. The dimer spectra present the same vibronic fine structure (though modestly compressed) as previously observed in the gas phase. The fluorescence lifetime and quantum yield of the dimer are found to be equal to those of the monomer, implying substantial inhibition of excimer formation in the dimer in helium.

  8. Quantum mechanical analysis of resonance Raman spectra of thymine

    NASA Astrophysics Data System (ADS)

    Burova, T. G.; Ten, G. N.; Kucherova, V. V.

    2003-07-01

    A direct quantum mechanical calculation of the relative intensities of lines in resonance Raman (RR) spectra of thymine was performed. The method of calculation is based on the adiabatic model in the Herzberg-Teller approximation. It is shown that the basic features of the intensity distribution in the spectra can be explained only by taking into account the vibronic mixing of electronic states and the contribution to the components of the scattering tensor from excited electronic states located close to the resonance state. The calculated results agree satisfactorily with experimental RR spectra of thymine excited by laser radiation at 266, 240, 218, and 200 nm. A comparative analysis of the intensity distribution in the RR spectra of thymine and uracil is carried out.

  9. Thermo-Reflectance Spectra of Eros: Unambiguous Detection of Olivine

    NASA Technical Reports Server (NTRS)

    Lucey, P. G.; Hinrichs, J. L.; Urquhart-Kelly, M.; Wellnitz, D.; Bell, J. F., III; Clark, B. E.

    2001-01-01

    Olivine is readily detected on 433 Eros using the new thermo-reflectance spectral technique applied to near-IR spectra obtained at Eros by the NEAR spacecraft. Additional information is contained in the original extended abstract.

  10. The Fossil Record of Star Formation from Galaxy Spectra 

    E-print Network

    Panter, Ben

    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 ...

  11. On the Interpretation of Supernova Light Echo Profiles and Spectra

    E-print Network

    Rest, A; Welch, D L; Foley, R J; Narayan, G; Mandel, K

    2010-01-01

    The light echo systems of historical supernovae in the Milky Way and local group galaxies provide an unprecedented opportunity to reveal the effects of asymmetry on observables, particularly optical spectra. Scattering dust at different locations on the light echo ellipsoid witnesses the supernova from different perspectives and the light consequently scattered towards Earth preserves the shape of line profile variations introduced by asymmetries in the supernova photosphere. However, the interpretation of supernova light echo spectra to date has not involved a detailed consideration of the effects of outburst duration and geometrical scattering modifications due to finite scattering dust filament dimension, inclination, and image point-spread function and spectrograph slit width. In this paper, we explore the implications of these factors and present a framework for future resolved supernova light echo spectra interpretation, and test it against Cas A and SN 1987A light echo spectra. We conclude that the ful...

  12. On the calibration of the IRAS low-resolution spectra

    NASA Technical Reports Server (NTRS)

    Volk, Kevin; Cohen, Martin

    1989-01-01

    The need for corrections to the LRS spectra based on a study of a number of normal stars observed by IRAS is discussed. The spectra of bright stars, such as alpha CMa, were found to be inconsistent with blackbody sources, this effect being generally observed in sources earlier than about K3. An attempt is made to correct the LRS spectra by changing the blackbody calibration temperature for Alpha Tau, assumed to be a 10,000-K blackbody source for the original LRS flux calibration. It is found that an anomalously low color temperature must be assumed for alpha Tau to produce reasonable results for earlier-type stars. Corrections based on a set of stars with well-determined effective temperatures are examined, as are the resulting color temperatures for 72 stars with Atlas spectra.

  13. Reflectance Spectra of Members of Very Young Asteroid Families

    NASA Astrophysics Data System (ADS)

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

    2009-03-01

    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.

  14. Electronic and vibrational spectra of two-dimensional quasicrystals

    NASA Astrophysics Data System (ADS)

    Odagaki, T.; Nguyen, D.

    1986-02-01

    The tight-binding electronic structure of two-dimensional quasicrystals is studied numerically for three patterns of Penrose tiling with up to 426 vertices. According to the range of interactions, three different models are considered. For the simplest model, two different interactions are assigned to long and short edges of the Penrose tile. Energy spectra show several significant gaps whose width and position depend on the relative strength of the interactions. The cumulative density of states is linear in energy at the band edge, indicating the existence of the Van Hove singularities. The energy spectra for other models show similar band gaps and singularities, though the density of states is asymmetric. Participation ratios are examined. When the relative strength of interactions becomes small, significant numbers of states become localized. Lattice vibration perpendicular to the plane is studied in the harmonic approximation for the simplest model. The vibrational spectra show gaps and singularities similar to the electronic spectra.

  15. Mammography X-Ray Spectra Simulated with Monte Carlo

    SciTech Connect

    Vega-Carrillo, H. R.; Gonzalez, J. Ramirez; Manzanares-Acuna, E.; Hernandez-Davila, V. M.; Villasana, R. Hernandez; Mercado, G. A. [Universidad Autonoma de Zacatecas Apdo. Postal 336, 98000 Zacatecas, Zac. Mexico (Mexico)

    2008-08-11

    Monte Carlo calculations have been carried out to obtain the x-ray spectra of various target-filter combinations for a mammography unit. Mammography is widely used to diagnose breast cancer. Further to Mo target with Mo filter combination, Rh/Rh, Mo/Rh, Mo/Al, Rh/Al, and W/Rh are also utilized. In this work Monte Carlo calculations, using MCNP 4C code, were carried out to estimate the x-ray spectra produced when a beam of 28 keV electrons did collide with Mo, Rh and W targets. Resulting x-ray spectra show characteristic x-rays and continuous bremsstrahlung. Spectra were also calculated including filters.

  16. Ensemble Learning Independent Component Analysis of Normal Galaxy Spectra

    E-print Network

    Honglin Lu; Hongyan Zhou; Junxian Wang; Tinggui Wang; Xiaobo Dong; Zhenquan Zhuang; Cheng Li

    2005-10-09

    In this paper, we employe a new statistical analysis technique, Ensemble Learning for Independent Component Analysis (EL-ICA), on the synthetic galaxy spectra from a newly released high resolution evolutionary model by Bruzual & Charlot. We find that EL-ICA can sufficiently compress the synthetic galaxy spectral library to 6 non-negative Independent Components (ICs), which are good templates to model huge amount of normal galaxy spectra, such as the galaxy spectra in the Sloan Digital Sky Survey (SDSS). Important spectral parameters, such as starlight reddening, stellar velocity dispersion, stellar mass and star formation histories, can be given simultaneously by the fit. Extensive tests show that the fit and the derived parameters are reliable for galaxy spectra with the typical quality of the SDSS.

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

    NASA Technical Reports Server (NTRS)

    White, W. F.

    1975-01-01

    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.

  18. Preliminary study on Raman spectra of nasopharyngeal carcinoma in vitro

    NASA Astrophysics Data System (ADS)

    Li, Yongzeng; Chen, Rong; Pan, Jianji; Feng, Shangyuan; Chen, Guannan; Huang, Wei; Lin, Wenshuo

    2007-11-01

    Nasopharyngeal carcinoma (NPC) is one of the malignant tumors threatening people's health and life which is mostly found in South China; early diagnosis is crucial to improve the effective treatment and higher survival rates. In this work, preliminary study on Raman spectra of nasopharyngeal carcinoma in vitro is reported. Spectra were obtained from normal and cancerous nasopharyngeal tissue which had undergone biopsy for high risk nasopharyngeal carcinoma. Factors effecting Raman spectra were also studied including sample storage time, spectral accumulation time. The results show that sample storage time has a negative effect on the measurement while increasing accumulation time does not appear to improve the spectra quality significantly. Consistent spectral differences appear to exist between normal and cancerous tissues, mainly in several bands. The results demonstrate Raman spectroscopy has the potential ability to detect and diagnose cancerous tissues. Future studies will advance toward true in vivo, real time and non-invasively.

  19. Analysis of gamma ray spectra measured by Mars Odyssey

    Microsoft Academic Search

    Larry G. Evans; Robert C. Reedy; Richard D. Starr; Kristopher E. Kerry; William V. Boynton

    2006-01-01

    Gamma ray spectra measured by the Mars Odyssey gamma ray spectrometer while in orbit around Mars were analyzed to identify the sources of 334 observed peaks and features. Most peaks were of a standard Gaussian shape with a low-energy tail. However, Doppler-broadened and sawtooth-shaped peaks were also observed in the spectra. The sources of most peaks were identified. Many peaks

  20. Multivariate analysis of light scattering spectra of liquid dairy products

    NASA Astrophysics Data System (ADS)

    Khodasevich, M. A.

    2010-05-01

    Visible light scattering spectra from the surface layer of samples of commercial liquid dairy products are recorded with a colorimeter. The principal component method is used to analyze these spectra. Vectors representing the samples of dairy products in a multidimensional space of spectral counts are projected onto a three-dimensional subspace of principal components. The magnitudes of these projections are found to depend on the type of dairy product.