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1

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

SciTech Connect

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

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

2004-07-11

2

Universal mean moment rate profiles of earthquake ruptures  

SciTech Connect

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

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

2006-05-15

3

On mutually unbiased bases  

E-print Network

Mutually unbiased bases for quantum degrees of freedom are central to all theoretical investigations and practical exploitations of complementary properties. Much is known about mutually unbiased bases, but there are also a fair number of important questions that have not been answered in full as yet. In particular, one can find maximal sets of ${N+1}$ mutually unbiased bases in Hilbert spaces of prime-power dimension ${N=p^\\m}$, with $p$ prime and $\\m$ a positive integer, and there is a continuum of mutually unbiased bases for a continuous degree of freedom, such as motion along a line. But not a single example of a maximal set is known if the dimension is another composite number ($N=6,10,12,...$). In this review, we present a unified approach in which the basis states are labeled by numbers ${0,1,2,...,N-1}$ that are both elements of a Galois field and ordinary integers. This dual nature permits a compact systematic construction of maximal sets of mutually unbiased bases when they are known to exist but throws no light on the open existence problem in other cases. We show how to use the thus constructed mutually unbiased bases in quantum-informatics applications, including dense coding, teleportation, entanglement swapping, covariant cloning, and state tomography, all of which rely on an explicit set of maximally entangled states (generalizations of the familiar two--q-bit Bell states) that are related to the mutually unbiased bases. There is a link to the mathematics of finite affine planes. We also exploit the one-to-one correspondence between unbiased bases and the complex Hadamard matrices that turn the bases into each other. The ultimate hope, not yet fulfilled, is that open questions about mutually unbiased bases can be related to open questions about Hadamard matrices or affine planes, in particular the ...[rest deleted

Thomas Durt; Berthold-Georg Englert; Ingemar Bengtsson; Karol ?yczkowski

2010-10-20

4

Weak mutually unbiased bases  

E-print Network

Quantum systems with variables in ${\\mathbb Z}(d)$ are considered. The properties of lines in the ${\\mathbb Z}(d)\\times {\\mathbb Z}(d)$ phase space of these systems, are studied. Weak mutually unbiased bases in these systems are defined as bases for which the overlap of any two vectors in two different bases, is equal to $d^{-1/2}$ or alternatively to one of the $d_i^{-1/2},0$ (where $d_i$ is a divisor of $d$ apart from $d,1$). They are designed for the geometry of the ${\\mathbb Z}(d)\\times {\\mathbb Z}(d)$ phase space, in the sense that there is a duality between the weak mutually unbiased bases and the maximal lines through the origin. In the special case of prime $d$, there are no divisors of $d$ apart from $1,d$ and the weak mutually unbiased bases are mutually unbiased bases.

M. Shalaby; A. Vourdas

2012-03-05

5

Real Mutually Unbiased Bases  

E-print Network

We tabulate bounds on the optimal number of mutually unbiased bases in R^d. For most dimensions d, it can be shown with relatively simple methods that either there are no real orthonormal bases that are mutually unbiased or the optimal number is at most either 2 or 3. We discuss the limitations of these methods when applied to all dimensions, shedding some light on the difficulty of obtaining tight bounds for the remaining dimensions that have the form d=16n^2, where n can be any number. We additionally give a simpler, alternative proof that there can be at most d/2+1 real mutually unbiased bases in dimension d instead of invoking the known results on extremal Euclidean line sets by Cameron and Seidel, Delsarte, and Calderbank et al.

P. Oscar Boykin; Meera Sitharam; Mohamad Tarifi; Pawel Wocjan

2005-09-13

6

Orbits of mutually unbiased bases  

E-print Network

We express Alltop's construction of mutually unbiased bases as orbits under the Weyl-Heisenberg group in prime dimensions and find a related construction in dimensions 2 and 4. We reproduce Alltop's mutually unbiased bases using abelian subgroups of the Clifford group in prime dimensions, in direct analogy to the well-known construction of mutually unbiased bases using abelian subgroups of the Weyl-Heisenberg group. Finally, we prove three theorems relating to the distances and linear dependencies among different sets of mutually unbiased bases.

Kate Blanchfield

2014-03-25

7

Constructions of Mutually Unbiased Bases  

E-print Network

Two orthonormal bases B and B' of a d-dimensional complex inner-product space are called mutually unbiased if and only if ||^2=1/d holds for all b in B and b' in B'. The size of any set containing (pairwise) mutually unbiased bases of C^d cannot exceed d+1. If d is a power of a prime, then extremal sets containing d+1 mutually unbiased bases are known to exist. We give a simplified proof of this fact based on the estimation of exponential sums. We discuss conjectures and open problems concerning the maximal number of mutually unbiased bases for arbitrary dimensions.

Andreas Klappenecker; Martin Roetteler

2003-09-15

8

The Mutually Unbiased Bases Revisited  

E-print Network

The study of Mutually Unbiased Bases continues to be developed vigorously, and presents several challenges in the Quantum Information Theory. Two orthonormal bases in $\\mathbb C^d, B {and} B'$ are said mutually unbiased if $\\forall b\\in B, b'\\in B'$ the scalar product $b\\cdot b'$ has modulus $d^{-1/2}$. In particular this property has been introduced in order to allow an optimization of the measurement-driven quantum evolution process of any state $\\psi \\in \\mathbb C^d$ when measured in the mutually unbiased bases $B\\_{j} {of} \\mathbb C^d$. At present it is an open problem to find the maximal umber of mutually Unbiased Bases when $d$ is not a power of a prime number. \

M. Combescure

2006-05-10

9

Spectra  

NSDL National Science Digital Library

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

The Exploratorium

2012-06-26

10

Entanglement in mutually unbiased bases  

E-print Network

One of the essential features of quantum mechanics is that most pairs of observables cannot be measured simultaneously. This phenomenon is most strongly manifested when observables are related to mutually unbiased bases. In this paper, we shed some light on the connection between mutually unbiased bases and another essential feature of quantum mechanics, quantum entanglement. It is shown that a complete set of mutually unbiased bases of a bipartite system contains a fixed amount of entanglement, independently of the choice of the set. This has implications for entanglement distribution among the states of a complete set. In prime-squared dimensions we present an explicit experiment-friendly construction of a complete set with a particularly simple entanglement distribution. Finally, we describe basic properties of mutually unbiased bases composed only of product states. The constructions are illustrated with explicit examples in low dimensions. We believe that properties of entanglement in mutually unbiased bases might be one of the ingredients to be taken into account to settle the question of the existence of complete sets. We also expect that they will be relevant to applications of bases in the experimental realization of quantum protocols in higher-dimensional Hilbert spaces.

M. Wiesniak; T. Paterek; A. Zeilinger

2011-05-27

11

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

NASA Astrophysics Data System (ADS)

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

Deif, A.; El-Hussain, I.

2012-12-01

12

Unbiased sampling of network ensembles  

NASA Astrophysics Data System (ADS)

Sampling random graphs with given properties is a key step in the analysis of networks, as random ensembles represent basic null models required to identify patterns such as communities and motifs. An important requirement is that the sampling process is unbiased and efficient. The main approaches are microcanonical, i.e. they sample graphs that match the enforced constraints exactly. Unfortunately, when applied to strongly heterogeneous networks (like most real-world examples), the majority of these approaches become biased and/or time-consuming. Moreover, the algorithms defined in the simplest cases, such as binary graphs with given degrees, are not easily generalizable to more complicated ensembles. Here we propose a solution to the problem via the introduction of a ‘Maximize and Sample’ (‘Max & Sam’ for short) method to correctly sample ensembles of networks where the constraints are ‘soft’, i.e. realized as ensemble averages. Our method is based on exact maximum-entropy distributions and is therefore unbiased by construction, even for strongly heterogeneous networks. It is also more computationally efficient than most microcanonical alternatives. Finally, it works for both binary and weighted networks with a variety of constraints, including combined degree-strength sequences and full reciprocity structure, for which no alternative method exists. Our canonical approach can in principle be turned into an unbiased microcanonical one, via a restriction to the relevant subset. Importantly, the analysis of the fluctuations of the constraints suggests that the microcanonical and canonical versions of all the ensembles considered here are not equivalent. We show various real-world applications and provide a code implementing all our algorithms.

Squartini, Tiziano; Mastrandrea, Rossana; Garlaschelli, Diego

2015-02-01

13

Mutually Unbiased Bases for Continuous Variables  

E-print Network

The concept of mutually unbiased bases is studied for N pairs of continuous variables. To find mutually unbiased bases reduces, for specific states related to the Heisenberg-Weyl group, to a problem of symplectic geometry. Given a single pair of continuous variables, three mutually unbiased bases are identified while five such bases are exhibited for two pairs of continuous variables. For N = 2, the golden ratio occurs in the definition of these mutually unbiased bases suggesting the relevance of number theory not only in the finite-dimensional setting.

Stefan Weigert; Michael Wilkinson

2008-11-09

14

Constructing Mutually Unbiased Bases in Dimension Six  

E-print Network

The density matrix of a qudit may be reconstructed with optimal efficiency if the expectation values of a specific set of observables are known. In dimension six, the required observables only exist if it is possible to identify six mutually unbiased complex 6x6 Hadamard matrices. Prescribing a first Hadamard matrix, we construct all others mutually unbiased to it, using algebraic computations performed by a computer program. We repeat this calculation many times, sampling all known complex Hadamard matrices, and we never find more than two that are mutually unbiased. This result adds considerable support to the conjecture that no seven mutually unbiased bases exist in dimension six.

Stephen Brierley; Stefan Weigert

2011-02-07

15

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

NASA Astrophysics Data System (ADS)

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.

Dragoni, M.; Lorenzano, E.

2015-02-01

16

On unbiased adaptive IIR filtering algorithms  

Microsoft Academic Search

Some properties of a recently proposed unbiased criteria for adaptive IIR filtering, namely the Master-slave Expanded Numerator Algorithm (XNA), is investigated. The XNA algorithm combines the minimization of two criteria that are quadratic in the parameters. Although the XNA method achieves an unbiased behavior in sufficient-order system identification applications, it generates undesired stationary points. Through the study presented in this

J. E. Cousseaut; P. D. Donate; P. S. R. Diniz

1998-01-01

17

Affine Constellations Without Mutually Unbiased Counterparts  

E-print Network

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

Stefan Weigert; Thomas Durt

2010-07-22

18

Entanglement detection using mutually unbiased measurements  

E-print Network

We study the entanglement detection by using mutually unbiased measurements and provide a quantum separability criterion that can be experimentally implemented for arbitrary $d$-dimensional bipartite systems. We show that this criterion is more effective than the criterion based on mutually unbiased bases. For isotropic states our criterion becomes both necessary and sufficient.

Bin Chen; Teng Ma; Shao-Ming Fei

2014-07-01

19

Classifying all mutually unbiased bases in Rel  

E-print Network

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.

Julia Evans; Ross Duncan; Alex Lang; Prakash Panangaden

2009-09-25

20

All Mutually Unbiased Product Bases in Dimension Six  

E-print Network

All mutually unbiased bases in dimension six consisting of product states only are constructed. Several continuous families of pairs and two triples of mutually unbiased product bases are found to exist but no quadruple. The exhaustive classification leads to a proof that a complete set of seven mutually unbiased bases, if it exists, cannot contain a triple of mutually unbiased product bases.

Daniel McNulty; Stefan Weigert

2012-03-24

21

Entanglement detection via mutually unbiased bases  

E-print Network

We investigate correlations among complementary observables. In particular, we show how to take advantage of mutually unbiased bases (MUBs) for the efficient detection of entanglement in arbitrarily high-dimensional, multipartite and continuous variable quantum systems. The introduced entanglement criteria are relatively easy to implement experimentally since they require only a few local measurement settings. In addition, we establish a link between the separability problem and the maximum number of mutually unbiased bases -- opening a new avenue in this long-standing open problem.

Christoph Spengler; Marcus Huber; Stephen Brierley; Theodor Adaktylos; Beatrix C. Hiesmayr

2012-08-07

22

Unbiased Volumetric Registration via Nonlinear Elastic Regularization  

E-print Network

elasticity method was tested using volumetric serial magnetic resonance images and shown to have someUnbiased Volumetric Registration via Nonlinear Elastic Regularization Igor Yanovsky1 , Carole Le of California, Los Angeles 2 Institute of Mathematical Research of Rennes, France 3 Laboratory of Neuro Imaging

Soatto, Stefano

23

Hadamard Matrices from Mutually Unbiased Bases  

E-print Network

An analytical method for getting new complex Hadamard matrices by using mutually unbiased bases and a nonlinear doubling formula is provided. The method is illustrated with the n=4 case that leads to a rich family of eight-dimensional Hadamard matrices that depend on five arbitrary parameters whose modulus is equal to unity.

Petre Dita

2010-03-19

24

Uncertainty relations based on mutually unbiased measurements  

NASA Astrophysics Data System (ADS)

We derive uncertainty relation inequalities according to the mutually unbiased measurements. Based on the calculation of the index of coincidence of probability distribution given by d+1 MUMs on any density operator ? in Cd , both state-dependent and state-independent forms of lower entropic bounds are given. Furthermore, we formulate uncertainty relations for MUMs in terms of Rényi and Tsallis entropies.

Chen, Bin; Fei, Shao-Ming

2015-02-01

25

Mutually unbiased bases and generalized Bell states  

E-print Network

We employ a straightforward relation between mutually unbiased and Bell bases to extend the latter in terms of a direct construction for the former. We analyze in detail the properties of these new generalized Bell states, showing that they constitute an appropriate tool for testing entanglement in bipartite multiqudit systems.

A. B. Klimov; D. Sych; L. L. Sanchez-Soto; G. Leuchs

2009-02-11

26

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

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

27

Maximally Entangled States via Mutual Unbiased collective Bases  

E-print Network

Relative and center of mass cordinates are used to generalize mutually unbiased bases (MUB) and define mutually unbiased bases (MUCB). Maximal entangled states are given as product staes in the collective varibles

M. Revzen

2009-10-17

28

ccsd00001371, Mutually Unbiased Bases and Finite Projective Planes  

E-print Network

ccsd­00001371, version 2 ­ 1 Jul 2004 Mutually Unbiased Bases and Finite Projective Planes Metod + 1 mutually unbiased bases in a d- dimensional Hilbert space if d di#11;ers from a power of prime-called mutually unbiased bases [see, e.g., 1{7], especially in the context of quantum state determination

29

Entanglement detection via mutually unbiased bases  

E-print Network

We investigate correlations among complementary observables. In particular, we show how to take advantage of mutually unbiased bases (MUBs) for the detection of entanglement in arbitrarily high-dimensional quantum systems. It is shown that their properties can be exploited to construct entanglement criteria which are experimentally implementable with few local measurement settings. The introduced concepts are not restricted to bipartite finite-dimensional systems, but are also applicable to continuous variables and multipartite systems. This is demonstrated by two examples -- the two-mode squeezed state and the Aharonov state. In addition, and more importantly from a theoretical point of view, we find a link between the separability problem and the maximum number of mutually unbiased bases.

Spengler, Christoph; Brierley, Stephen; Adaktylos, Theodor; Hiesmayr, Beatrix C

2012-01-01

30

Unbiased nonorthogonal bases for tomographic reconstruction  

SciTech Connect

We have developed a general method for constructing a set of nonorthogonal bases with equal separations between all different basis states in prime dimensions. The results are that the corresponding biorthogonal counterparts are pairwise unbiased with the components of the original bases. Using these bases, we derive an explicit expression for the optimal tomography in nonorthogonal bases. A special two-dimensional case is analyzed separately.

Sainz, Isabel; Klimov, Andrei B. [Departamento de Fisica, Universidad de Guadalajara, Revolucion 1500, Guadalajara, Jalisco 44420 (Mexico); Roa, Luis [Center of Quantum Optics and Quantum Information, Center for Optics and Photonics, Departamento de Fisica, Universidad de Concepcion, Casilla-160C, Concepcion (Chile)

2010-05-15

31

Unbiased shifts of Brownian motion Gunter Last  

E-print Network

= (Bt)tR be a two-sided standard Brownian motion. An unbiased shift of B is a random time T, which is a measurable function of B, such that (BT+t -BT )tR is a Brownian motion independent of BT . We characterise distribution on R we construct a stopping time T 0 with the above properties such that BT has distribution

32

Arithmetic, mutually unbiased bases and complementary observables  

SciTech Connect

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

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

2010-02-15

33

Decision rules for unbiased inventory estimates  

NASA Technical Reports Server (NTRS)

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

Argentiero, P. D.; Koch, D.

1979-01-01

34

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

35

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

NASA Astrophysics Data System (ADS)

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.

Seyfarth, Ulrich; Ranade, Kedar S.

2012-06-01

36

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

E-print Network

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.

Ulrich Seyfarth; Kedar S. Ranade

2012-03-27

37

Mutually Unbiased Bases and Semi-definite Programming  

E-print Network

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

Stephen Brierley; Stefan Weigert

2010-06-01

38

Unbiased Inclination Distributions for Objects in the Kuiper Belt  

E-print Network

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 ...

Gulbis, Amanda A. S.

39

On Uncertainty Relations and Entanglement Detection with Mutually Unbiased Measurements  

NASA Astrophysics Data System (ADS)

We formulate some properties of a set of several mutually unbiased measurements. These properties are used for deriving entropic uncertainty relations. Applications of mutually unbiased measurements in entanglement detection are also revisited. First, we estimate from above the sum of the indices of coincidence for several mutually unbiased measurements. Further, we derive entropic uncertainty relations in terms of the Rényi and Tsallis entropies. Both the state-dependent and state-independent formulations are obtained. Using the two sets of local mutually unbiased measurements, a method of entanglement detection in bipartite finite-dimensional systems may be realized. A certain trade-off between a sensitivity of the scheme and its experimental complexity is discussed.

Rastegin, Alexey E.

2015-03-01

40

On uncertainty relations and entanglement detection with mutually unbiased measurements  

E-print Network

We formulate some properties of a set of several mutually unbiased measurements. These properties are used for deriving entropic uncertainty relations. Applications of mutually unbiased measurements in entanglement detection are also revisited. First, we estimate from above the sum of the indices of coincidence for several mutually unbiased measurements. Further, we derive entropic uncertainty relations in terms of the R\\'{e}nyi and Tsallis entropies. Both the state-dependent and state-independent formulations are obtained. Using the two sets of local mutually unbiased measurements, a method of entanglement detection in bipartite finite-dimensional systems may be realized. A certain trade-off between a sensitivity of the scheme and its experimental complexity is discussed.

Alexey E. Rastegin

2014-07-28

41

Unbiased estimators of wildlife population densities using aural information  

E-print Network

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

Durland, Eric Newton

1969-01-01

42

Maximally entangled states via mutual unbiased collective bases  

SciTech Connect

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

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

2010-01-15

43

Cyclic mutually unbiased bases, Fibonacci polynomials and Wiedemann's Ulrich Seyfarth and Kedar S. Ranade  

E-print Network

Cyclic mutually unbiased bases, Fibonacci polynomials and Wiedemann's conjecture Ulrich Seyfarth) Cyclic mutually unbiased bases, Fibonacci polynomials and Wiedemann's conjecture Ulrich Seyfarth1,a relate the construction of a complete set of cyclic mutually unbiased bases, i.e., mutually unbiased

44

Entanglement patterns in mutually unbiased basis sets  

SciTech Connect

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.

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

45

Practical implementation of mutually unbiased bases using quantum circuits  

NASA Astrophysics Data System (ADS)

The number of measurements necessary to perform the quantum state reconstruction of a system of qubits grows exponentially with the number of constituents, creating a major obstacle for the design of scalable tomographic schemes. We work out a simple and efficient method based on cyclic generation of mutually unbiased bases. The basic generator requires only Hadamard and controlled-phase gates, which are available in most practical realizations of these systems. We show how complete sets of mutually unbiased bases with different entanglement structures can be realized for three and four qubits. We also analyze the quantum circuits implementing the various entanglement classes.

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

2015-03-01

46

Practical implementation of mutually unbiased bases using quantum circuits  

E-print Network

The number of measurements necessary to perform the quantum state reconstruction of a system of qubits grows exponentially with the number of constituents, creating a major obstacle for the design of scalable tomographic schemes. We work out a simple and efficient method based on cyclic generation of mutually unbiased bases. The basic generator requires only Hadamard and controlled-phase gates, which are available in most practical realizations of these systems. We show how complete sets of mutually unbiased bases with different entanglement structures can be realized for three and four qubits. We also analyze the quantum circuits implementing the various entanglement classes.

U. Seyfarth; L. L. Sanchez-Soto; G. Leuchs

2014-12-14

47

Three Ways to Look at Mutually Unbiased Bases  

NASA Astrophysics Data System (ADS)

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

Bengtsson, Ingemar

2007-02-01

48

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

E-print Network

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

Van Den Eijnden, Eric

49

Multi-scale Unbiased Diffeomorphic Atlas Construction on , Jens Kruger  

E-print Network

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

Silva, Claudio T.

50

Robustness of a quantum key distribution with two and three mutually unbiased bases  

Microsoft Academic Search

We study the robustness of various protocols for quantum key distributions. We first consider the case of qutrits and study quantum protocols that employ two and three mutually unbiased bases. We then derive the optimal eavesdropping strategy for two mutually unbiased bases in dimension 4 and generalize the result to a quantum key distribution protocol that uses two mutually unbiased

Filippo Caruso; Helle Bechmann-Pasquinucci; Chiara Macchiavello

2005-01-01

51

Designs Mutually unbiased bases 2-designs from bases Open problems Optimal complex projective designs  

E-print Network

Designs Mutually unbiased bases 2-designs from bases Open problems Optimal complex projective designs Aidan Roy November 6, 2009 #12;Designs Mutually unbiased bases 2-designs from bases Open problems , with equality if and only if X is a t-design. #12;Designs Mutually unbiased bases 2-designs from bases Open

Cameron, Peter

52

Caustic Forecasting: Unbiased Estimation of Caustic Lighting for Global Illumination  

E-print Network

We present an unbiased method for generating caustic lighting using importance sampled Path Tracing with Caustic Forecasting. Our technique is part of a straightforward rendering scheme which extends the Illumination by Weak Singularities method to allow for fully unbiased global illumination with rapid convergence. A photon shooting preprocess, similar to that used in Photon Mapping, generates photons that interact with specular geometry. These photons are then clustered, effectively dividing the scene into regions which will contribute similar amounts of caustic lighting to the image. Finally, the photons are stored into spatial data structures associated with each cluster, and the clusters themselves are organized into a spatial data structure for fast searching. During rendering we use clusters to decide the caustic energy importance of a region, and use the local photons to aid in importance sampling, effectively reducing the number of samples required to capture caustic lighting.

T. Igarashi; N. Max; F. Sillion; B. C. Budge; J. C. Anderson; K. I. Joy

53

Encryption via Entangled states belonging to Mutually Unbiased Bases  

E-print Network

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.

M. Revzen; F. C. Khanna

2008-09-11

54

Quantum phase uncertainty in mutually unbiased measurements and Gauss sums  

Microsoft Academic Search

Mutually unbiased bases (MUBs), which are such that the inner product between two vectors in different orthogonal bases is constant equal to the inverse 1\\/&surd;d, with d the dimension of the finite Hilbert space, are becoming more and more studied for applications such as quantum tomography and cryptography, and in relation to entangled states and to the Heisenberg-Weil group of

Michel Planat; Haret Rosu

2005-01-01

55

Unbiased Minimum Variance Estimation Of Correlation Functions Of Random Signals  

Microsoft Academic Search

In this paper, we present the unbiased minimum variance estimation of the correlation function, rxx(k), of a wide-sense stationary random signal x(k). However, the obtained theoretical minimum variance estimator, Yxx(k), for rxx(k) is a function of not only x(k) but also the unknown rxx(k) and thus is not computable. Additionally, FXx(k) is not computationally efficient. We, therefore, propose a modified

Chong-Yung Chi; Wu-Ton Chen

1990-01-01

56

Unextendible maximally entangled bases and mutually unbiased bases  

E-print Network

We study unextendible maximally entangled basis in arbitrary bipartite spaces. A systematic way of constructing a set of $d^{2}$ orthonormal maximally entangled states in $\\mathbb{C}^{d}\\bigotimes\\mathbb{C}^{d'}(\\frac{d'}{2}bases in which all the bases are unextendible maximally entangled ones. We present two unextendible maximally entangled bases in $\\mathbb{C}^{2}\\bigotimes\\mathbb{C}^{3}$ which are mutually unbiased.

Bin Chen; Shao-Ming Fei

2013-09-13

57

Unbiased estimators for spatial distribution functions of classical fluids.  

PubMed

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

Adib, Artur B; Jarzynski, Christopher

2005-01-01

58

All Mutually Unbiased Bases in Dimensions Two to Five  

E-print Network

All complex Hadamard matrices in dimensions two to five are known. We use this fact to derive all inequivalent sets of mutually unbiased (MU) bases in low dimensions. We find a three-parameter family of triples of MU bases in dimension four and two inequivalent classes of MU triples in dimension five. We confirm that the complete sets of (d+1) MU bases are unique (up to equivalence) in dimensions below six, using only elementary arguments for d less than five.

Stephen Brierley; Stefan Weigert; Ingemar Bengtsson

2010-08-06

59

On the mathematical foundations of mutually unbiased bases  

E-print Network

In order to describe the right setting to handle Zauner's conjecture on mutually unbiased bases (MUBs) (saying that in $\\mathbb{C}^d$, a set of MUBs of the theoretical maximal size $d + 1$ exists only if $d$ is a prime power), we pose some fundamental questions which naturally arise. Some of these questions have important consequences for the construction theory of (new) sets of maximal MUBs.

Koen Thas

2014-09-11

60

Unbiased stereological quantification of neurons in the human spiral ganglion.  

PubMed

We applied an unbiased stereological technique, the optical fractionator, on five human archival temporal bone specimens to estimate the total number of spiral ganglion neurons. Available archival human temporal bone specimen has been serially sectioned at 20 microm and every tenth section was stained. All the stained sections passing through the spiral ganglion were used for the analysis. From each section sampled, the counting areas were systematically randomly sampled within the sectional area of the spiral ganglion. The neurons within the counting areas sampled were counted with the optical disector technique. The total number of the human spiral ganglion neurons was estimated by multiplying the number of neurons counted by the reciprocal of the aggregate sampling fraction. We found an average of 41700 neurons with a coefficient of variation of 0.14, which is a significant departure from the previously published data obtained with the assumption-based methods. The mean coefficient of error for the stereological estimates of the total number of human spiral ganglion neurons was 0.078. The present report presents unbiased stereological sampling and counting strategies for the future quantitative studies on the spiral ganglion neurons. The result of the present study provides the first unbiased baseline value of the human spiral ganglion neurons. PMID:11335063

Ishiyama, A; Agena, J; Lopez, I; Tang, Y

2001-05-18

61

Mutually Unbiased Bases and Complementary Spin 1 Observables  

E-print Network

The two observables are complementary if they cannot be measured simultaneously, however they become maximally complementary if their eigenstates are mutually unbiased. Only then the measurement of one observable gives no information about the other observable. The spin projection operators onto three mutually orthogonal directions are maximally complementary only for the spin 1/2. For the higher spin numbers they are no longer unbiased. In this work we examine the properties of spin 1 Mutually Unbiased Bases (MUBs) and look for the physical meaning of the corresponding operators. We show that if the computational basis is chosen to be the eigenbasis of the spin projection operator onto some direction z, the states of the other MUBs have to be squeezed. Then, we introduce the analogs of momentum and position operators and interpret what information about the spin vector the observer gains while measuring them. Finally, we study the generation and the measurement of MUBs states by introducing the Fourier like transform through spin squeezing. The higher spin numbers are also considered.

Pawel Kurzynski; Wawrzyniec Kaszub; Mikolaj Czechlewski

2009-05-11

62

Unbiased Water and Methanol Maser Surveys of NGC 1333  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

63

Experimental quantum tomography of photonic qudits via mutually unbiased basis  

E-print Network

We present the experimental quantum tomography of 7- and 8-dimensional quantum systems based on projective measurements in the mutually unbiased basis (MUB-QT). One of the advantages of MUB-QT is that it requires projections from a minimal number of bases to be performed. In our scheme, the higher dimensional quantum systems are encoded using the propagation modes of single photons, and we take advantage of the capabilities of amplitude- and phase-modulation of programmable spatial light modulators to implement the MUB-QT.

G. Lima; L. Neves; R. Guzmán; E. S. Gómez; W. A. T. Nogueira; A. Delgado; A. Vargas; C. Saavedra

2011-02-09

64

Unbiased Estimation of Mutation Rates under Fluctuating Final Counts  

PubMed Central

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

Ycart, Bernard; Veziris, Nicolas

2014-01-01

65

Robustness of a quantum key distribution with two and three mutually unbiased bases  

E-print Network

We study the robustness of various protocols for quantum key distribution. We first consider the case of qutrits and study quantum protocols that employ two and three mutually unbiased bases. We then derive the optimal eavesdropping strategy for two mutually unbiased bases in dimension four and generalize the result to a quantum key distribution protocol that uses two mutually unbiased bases in arbitrary finite dimension.

Filippo Caruso; Helle Bechmann-Pasquinucci; Chiara Macchiavello

2006-02-02

66

Quantitating Glomerular Endothelial Fenestration: An Unbiased Stereological Approach  

PubMed Central

Background/Aims Glomerular endothelial cells are fenestrated, allowing for especially high transcellular hydraulic conductivity. Current knowledge about endothelial fenestration structural changes in disease conditions is limited, partly due to the absence of robust methodologies to quantitate these structures. Herein, we propose a novel method for estimating the percentage of endothelial fenestration. Methods An unbiased stereological method based on contiguity of two phases and surface area density estimation using isotropic uniform random line probes was developed. A line grid for intercept counting and classifying endothelial coverage of fenestrated versus non-fenestrated areas was designed. The method was applied to renal biopsies from 15 patients with Fabry disease and 9 normal living kidney donor controls. Results The percentage of glomerular capillary endothelial coverage which was fenestrated was lower in Fabry patients (43 ± 12%) versus controls (53 ± 9%; p = 0.047). The fraction of endothelial surface which was fenestrated was greater on the peripheral versus mesangial zones of the capillary walls in both Fabry patients (p = 0.00002) and controls (p = 0.0005). Conclusion The proposed method provides an unbiased tool to quantitate endothelial fenestration changes in glomeruli. The practical example introduced showed reduced glomerular endothelial fenestration in Fabry nephropathy. PMID:21659733

Najafian, Behzad; Mauer, Michael

2011-01-01

67

Unbiased constraints on the clumpiness of universe from standard candles  

E-print Network

We perform unbiased tests for the clumpiness of 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 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 $\\Omega_m$ as well as clumpiness parameter $\\eta$ which quantifies the fraction of homogeneously distributed matter within a given light cone. At 1$\\sigma$ confidence level, the constraints are $\\Omega_m=0.34\\pm0.02$ and $\\eta=1.00^{+0.00}_{-0.02}$ from the ...

Li, Zhengxiang; Zhu, Zong-Hong

2015-01-01

68

atomic spectra 1 Atomic Spectra  

E-print Network

Physics, pp. 88-93 (Rutherford nuclear model), 93-106 (atomic structure and electron spectra) 2. D. Watomic spectra 1 Atomic Spectra '96, THK-MRM Object To become familiar with the construction and interpret spin-orbit doublets and triplets in alkali spectra. References 1. Serway, Moses and Moyer: Modern

Glashausser, Charles

69

Maximum likelihood: Extracting unbiased information from complex networks  

NASA Astrophysics Data System (ADS)

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

Garlaschelli, Diego; Loffredo, Maria I.

2008-07-01

70

Best linear unbiased estimation of the nuclear masses  

E-print Network

This paper presents methods to provide an optimal evaluation of the nuclear masses. The techniques used for this purpose come from data assimilation that allows combining, in an optimal and consistent way, information coming from experiment and from numerical model. Using all the available information, it leads to improve not only masses evaluations, but also to decrease uncertainties. Each newly evaluated mass value is associated with some accuracy that is sensibly reduced with respect to the values given in tables, especially in the case of the less well-known masses. In this paper, we first introduce a useful tool of data assimilation, the Best Linear Unbiased Estimation (BLUE). This BLUE method is applied to nuclear mass tables and some results of improvement are shown.

Bertrand Bouriquet; Jean-Philippe Argaud

2011-05-24

71

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

E-print Network

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

Markopoulou, Athina

72

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

E-print Network

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

Paris-Sud XI, Université de

73

All-optical injection of ballistic electrical currents in unbiased silicon  

E-print Network

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

Loss, Daniel

74

Entropic uncertainty relations and locking: tight bounds for mutually unbiased bases  

E-print Network

We prove tight entropic uncertainty relations for a large number of mutually unbiased measurements. In particular, we show that a bound derived from the result by Maassen and Uffink for 2 such measurements can in fact be tight for up to sqrt{d} measurements in mutually unbiased bases. We then show that using more mutually unbiased bases does not always lead to a better locking effect. We prove that the optimal bound for the accessible information using up to sqrt{d} specific mutually unbiased bases is log d/2, which is the same as can be achieved by using only two bases. Our result indicates that merely using mutually unbiased bases is not sufficient to achieve a strong locking effect, and we need to look for additional properties.

Manuel A. Ballester; Stephanie Wehner

2007-03-21

75

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

SciTech Connect

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.

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

2013-10-15

76

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

77

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

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

78

Acceleration spectra for subduction zone earthquakes  

USGS Publications Warehouse

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

Boatwright, J.; Choy, G.L.

1989-01-01

79

Depicting qudit quantum mechanics and mutually unbiased qudit theories  

E-print Network

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

André Ranchin

2014-12-30

80

Unbiased water and methanol maser surveys of NGC 1333  

E-print Network

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

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

2014-01-01

81

Unbiased determination of polarized parton distributions and their uncertainties  

NASA Astrophysics Data System (ADS)

We present a determination of a set of polarized parton distributions (PDFs) of the nucleon, at next-to-leading order, from a global set of longitudinally polarized deep-inelastic scattering data: NNPDFpol1.0. The determination is based on the NNPDF methodology: a Monte Carlo approach, with neural networks used as unbiased interpolants, previously applied to the determination of unpolarized parton distributions, and designed to provide a faithful and statistically sound representation of PDF uncertainties. We present our dataset, its statistical features, and its Monte Carlo representation. We summarize the technique used to solve the polarized evolution equations and its benchmarking, and the method used to compute physical observables. We review the NNPDF methodology for parametrization and fitting of neural networks, the algorithm used to determine the optimal fit, and its adaptation to the polarized case. We finally present our set of polarized parton distributions. We discuss its statistical properties, test for its stability upon various modifications of the fitting procedure, and compare it to other recent polarized parton sets, and in particular obtain predictions for polarized first moments of PDFs based on it. We find that the uncertainties on the gluon, and to a lesser extent the strange PDF, were substantially underestimated in previous determinations.

Ball, Richard D.; Forte, Stefano; Guffanti, Alberto; Nocera, Emanuele R.; Ridolfi, Giovanni; Rojo, Juan

2013-09-01

82

Unbiased Approach for Virus Detection in Skin Lesions  

PubMed Central

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

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

2013-01-01

83

Unbiased approach for virus detection in skin lesions.  

PubMed

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

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

2013-01-01

84

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

E-print Network

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 ...

Amit, Ido

85

Antenna-coupled unbiased detectors for LW-IR regime  

NASA Astrophysics Data System (ADS)

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

Tiwari, Badri Nath

86

UNBIASED INCLINATION DISTRIBUTIONS FOR OBJECTS IN THE KUIPER BELT  

SciTech Connect

Using data from the Deep Ecliptic Survey (DES), we investigate the inclination distributions of objects in the Kuiper Belt. We present a derivation for observational bias removal and use this procedure to generate unbiased inclination distributions for Kuiper Belt objects (KBOs) of different DES dynamical classes, with respect to the Kuiper Belt plane. Consistent with previous results, we find that the inclination distribution for all DES KBOs is well fit by the sum of two Gaussians, or a Gaussian plus a generalized Lorentzian, multiplied by sin i. Approximately 80% of KBOs are in the high-inclination grouping. We find that Classical object inclinations are well fit by sin i multiplied by the sum of two Gaussians, with roughly even distribution between Gaussians of widths 2.0{sup +0.6}{sub -0.5}{sup 0} and 8.1{sup +2.6}{sub -2.1}{sup 0}. Objects in different resonances exhibit different inclination distributions. The inclinations of Scattered objects are best matched by sin i multiplied by a single Gaussian that is centered at 19.1{sup +3.9}{sub -3.6}{sup 0} with a width of 6.9{sup +4.1}{sub -2.7}{sup 0}. Centaur inclinations peak just below 20{sup 0}, with one exceptionally high-inclination object near 80{sup 0}. The currently observed inclination distribution of the Centaurs is not dissimilar to that of the Scattered Extended KBOs and Jupiter-family comets, but is significantly different from the Classical and Resonant KBOs. While the sample sizes of some dynamical classes are still small, these results should begin to serve as a critical diagnostic for models of solar system evolution.

Gulbis, A. A. S. [South African Astronomical Observatory, P.O. Box 9, Observatory, 7935 Cape Town (South Africa); Elliot, J. L.; Adams, E. R. [Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307 (United States); Benecchi, S. D. [Planetary Science Institute, 1700 East Fort Lowell, Suite 106, Tucson, AZ 85719 (United States); Buie, M. W. [Department of Space Studies, Southwest Research Institute, 1050 Walnut Street 400, Boulder, CO 80302 (United States); Trilling, D. E. [Department of Physics and Astronomy, Northern Arizona University, P.O. Box 6010, Flagstaff, AZ 86011 (United States); Wasserman, L. H., E-mail: amanda@saao.ac.z, E-mail: jle@mit.ed, E-mail: era@mit.ed, E-mail: lhw@lowell.ed, E-mail: susank@psi.ed, E-mail: buie@boulder.swri.ed, E-mail: David.Trilling@nau.ed [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States)

2010-08-15

87

The role of unbiased perturbations towards providing estimator robustness with pragmatic geometric methods  

E-print Network

THE ROLE OF UNBIASED PERTURBATIONS TOWARDS PROVIDING ESTIMATOR ROBUSTNESS WITH PRAGMATIC GEOMETRIC METHODS A Thesis by VISHAL VINOD VARMA Submitted to the Office of Graduate Studies of Texas ARM University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE December 2002 Major Subject: Electrical Engineering THE ROLE OF UNBIASED PERTURBATIONS TOWARDS PROVIDING ESTIMATOR ROBUSTNESS WITH PRAGMATIC GEOMETRIC METHODS A Thesis by VISHAL VINOD VARMA Submitted...

Varma, Vishal Vinod

2002-01-01

88

A novel computational method for comparing vibrational circular dichroism spectra  

NASA Astrophysics Data System (ADS)

A novel method, SimIR/VCD, for comparing experimental and calculated VCD (vibrational circular dichroism) spectra is developed, based on newly defined spectra similarities. With computationally optimized frequency scaling and shifting, a calculated spectrum can be easily identified to match an observed spectrum, which leads to an unbiased molecular chirality assignment. The time-consuming manual band-fitting work is greatly reduced. With (1S)-(-)-?-pinene as an example, it demonstrates that the calculated VCD similarity is correlated with VCD spectra matching quality and has enough sensitivity to identify variations in the spectra. The study also compares spectra calculated using different DFT methods and basis sets. Using this method should facilitate the spectra matching, reduce human error and provide a confidence measure in the chiral assignment using VCD spectroscopy.

Shen, Jian; Zhu, Chengyue; Reiling, Stephan; Vaz, Roy

2010-08-01

89

40 orbits of UDF observations with the ACS grism Spectra for every source in the field.  

E-print Network

Motivation · 40 orbits of UDF observations with the ACS grism · Spectra for every source in the field. · Good S/N continuum detections to I(AB) ~ 27; about 30% of UDF sources. · Spectral. Tsvetanov J. Vernet, J. Walsh, R. Windhorst, H.J. Yan Deepest Unbiased Spectroscopy yet. I(AB) UDF

90

On mutually unbiased bases: Passing from d to d2 M. R. Kibler1,2,3  

E-print Network

On mutually unbiased bases: Passing from d to d2 dimensions M. R. Kibler1,2,3 1 Universit´e de Lyon + 1 mutually unbiased bases in Cd into the one of finding d(d + 1) vectors in Cd2 . The transformation; mutually unbiased bases; projection operators; Gauss sums PACS: 03.65.Fd, 03.65.Ta, 03.65.Ud in2p3

Paris-Sud XI, Université de

91

On mutually unbiased bases: Passing from d to d2 M. R. Kibler1,2,3  

E-print Network

On mutually unbiased bases: Passing from d to d2 dimensions M. R. Kibler1,2,3 1 Universit´e de Lyon + 1 mutually unbiased bases in Cd into the one of finding d(d + 1) vectors in Cd2 . The transformation; mutually unbiased bases; projection operators; Gauss sums PACS: 03.65.Fd, 03.65.Ta, 03.65.Ud in2p3

92

Atomic Spectra  

NSDL National Science Digital Library

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

Nave, Carl R.

93

The correspondence between mutually unbiased bases and mutually orthogonal extraordinary supersquares  

E-print Network

We study the connection between mutually unbiased bases and mutually orthogonal extraordinary supersquares, a wider class of squares which does not contain only the Latin squares. We show that there are four types of complete sets of mutually orthogonal extraordinary supersquares for the dimension $d=8$. We introduce the concept of physical striation and show that this is equivalent to the extraordinary supersquare. The general algorithm for obtaining the mutually unbiased bases and the physical striations is constructed and it is shown that the complete set of mutually unbiased physical striations is equivalent to the complete set of mutually orthogonal extraordinary supersquares. We apply the algorithm to two examples: one for two-qubit systems ($d=4$) and one for three-qubit systems ($d=8$), by using the Type II complete sets of mutually orthogonal extraordinary supersquares of order 8.

Iulia Ghiu; Cristian Ghiu

2014-04-23

94

Hierarchical thinking in network biology: the unbiased modularization of biochemical networks.  

PubMed

As reconstructed biochemical reaction networks continue to grow in size and scope, there is a growing need to describe the functional modules within them. Such modules facilitate the study of biological processes by deconstructing complex biological networks into conceptually simple entities. The definition of network modules is often based on intuitive reasoning. As an alternative, methods are being developed for defining biochemical network modules in an unbiased fashion. These unbiased network modules are mathematically derived from the structure of the whole network under consideration. PMID:15544950

Papin, Jason A; Reed, Jennifer L; Palsson, Bernhard O

2004-12-01

95

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

SciTech Connect

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

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

2011-06-15

96

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

E-print Network

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

Philippe Raynal; Xin Lü; Berthold-Georg Englert

2011-03-05

97

A Note on Mutually Unbiased Unextendible Maximally Entangled Bases in $\\mathbb{C}^{2}\\bigotimes \\mathbb{C}^{3}$  

E-print Network

We systematically study the construction of mutually unbiased bases in $\\mathbb{C}^{2}\\bigotimes\\mathbb{C}^{3}$, such that all the bases are unextendible maximally entangled ones. Necessary conditions of constructing a pair of mutually unbiased unextendible maximally entangled bases in $\\mathbb{C}^{2}\\bigotimes\\mathbb{C}^{3}$ are derived. Explicit examples are presented.

Halqem Nizamidin; Teng Ma; Shao-Ming Fei

2015-01-22

98

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

Microsoft Academic Search

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

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

2010-01-01

99

Incremental Grammatical Inference From Positive And Negative Data Using Unbiased Finite State Automata  

Microsoft Academic Search

The induction of regular languages (or associated recognizers) from examples hasattracted much attention from researchers. The most part of the known methods forregular grammatical inference only use positive examples. Recently, new symbolicand neural approaches have been proposed to induce finite state automata from bothpositive and negative data. In this paper we present a type of Moore machines, thatwe call Unbiased

R. Alquezar; A. Sanfeliu

1994-01-01

100

Multiple events on single molecules: Unbiased estimation in single-molecule biophysics  

E-print Network

Multiple events on single molecules: Unbiased estimation in single-molecule biophysics Daniel A, Princeton, NJ, December 6, 2005 (received for review June 24, 2005) Most analyses of single-molecule of a motor protein acting on a single molecule must not exceed the total molecule length. We have developed

Dekker, Nynke

101

Estimating Unbiased Treatment Effects in Education Using a Regression Discontinuity Design  

ERIC Educational Resources Information Center

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

Smith, William C.

2014-01-01

102

Automated and unbiased classification of chemical profiles from fungi using high performance liquid chromatography  

Microsoft Academic Search

In this paper we present a method for unbiased\\/unsupervised classification and identification of closely related fungi, using chemical analysis of secondary metabolite profiles created by HPLC with UV diode array detection. For two chromatographic data matrices a vector of locally aligned full spectral similarities is calculated along the retention time axis. The vector depicts the evaluating of the alikeness between

Michael Edberg Hansen; Birgitte Andersen; Jørn Smedsgaard

2005-01-01

103

Mutations that Reduce Aggregation of the Alzheimer's Ab42 Peptide: an Unbiased Search for the Sequence  

E-print Network

Mutations that Reduce Aggregation of the Alzheimer's Ab42 Peptide: an Unbiased Search in the brains of Alzheimer's patients is the 42 residue amyloid-b-peptide (Ab42). Although the amino acid Keywords: Alzheimer's disease; amyloid-b peptide variant; protein aggregation; amyloidogenesis; green

Hecht, Michael H.

104

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

PubMed

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

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

2013-01-01

105

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

106

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

PubMed Central

Models of mammalian regulatory networks controlling gene expression have been inferred from genomic data, yet have largely not been validated. We present an unbiased strategy to systematically perturb candidate regulators and monitor cellular transcriptional responses. We apply this approach to derive regulatory networks that control the transcriptional response of mouse primary dendritic cells (DCs) to pathogens. Our approach revealed the regulatory functions of 125 transcription factors, chromatin modifiers, and RNA binding proteins and constructed a network model consisting of two dozen core regulators and 76 fine-tuners that help explain how pathogen-sensing pathways achieve specificity. This study establishes a broadly-applicable, comprehensive and unbiased approach to reveal the wiring and functions of a regulatory network controlling a major transcriptional response in primary mammalian cells. PMID:19729616

Amit, Ido; Garber, Manuel; Chevrier, Nicolas; Leite, Ana Paula; Donner, Yoni; Eisenhaure, Thomas; Guttman, Mitchell; Grenier, Jennifer K.; Li, Weibo; Zuk, Or; Schubert, Lisa A.; Birditt, Brian; Shay, Tal; Goren, Alon; Zhang, Xiaolan; Smith, Zachary; Deering, Raquel; McDonald, Rebecca C.; Cabili, Moran; Bernstein, Bradley E; Rinn, John L.; Meissner, Alex; Root, David E.; Hacohen, Nir; Regev, Aviv

2010-01-01

107

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

PubMed

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

Waxman, D; Peck, J R

2004-12-01

108

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

E-print Network

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.

Alejandro Gangui; Jerome Martin

2001-02-22

109

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

SciTech Connect

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

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

2010-08-15

110

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

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

111

Measuring spectra using burst-mode LDA  

NASA Astrophysics Data System (ADS)

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

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

2008-11-01

112

FAST TRACK COMMUNICATION: Qudits of composite dimension, mutually unbiased bases and projective ring geometry  

Microsoft Academic Search

The d2 Pauli operators attached to a composite qudit in dimension d may be mapped to the vectors of the symplectic module \\\\mathcal{Z}_d^{2} (\\\\mathcal{Z}_d being the modular ring). As a result, perpendicular vectors correspond to commuting operators, a free cyclic submodule to a maximal commuting set, and disjoint such sets to mutually unbiased bases. For dimensions d = 6, 10,

Michel Planat; Anne-Céline Baboin

2007-01-01

113

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

114

A Survey of Finite Algebraic Geometrical Structures Underlying Mutually Unbiased Quantum Measurements  

E-print Network

The basic methods of constructing the sets of mutually unbiased bases in the Hilbert space of an arbitrary finite dimension are discussed and an emerging link between them is outlined. It is shown that these methods employ a wide range of important mathematical concepts like, e.g., Fourier transforms, Galois fields and rings, finite and related projective geometries, and entanglement, to mention a few. Some applications of the theory to quantum information tasks are also mentioned.

Michel R. P. Planat; Haret Rosu; Serge Perrine; Metod Saniga

2006-10-12

115

Extending unbiased stereology of brain ultrastructure to three-dimensional volumes  

NASA Technical Reports Server (NTRS)

OBJECTIVE: Analysis of brain ultrastructure is needed to reveal how neurons communicate with one another via synapses and how disease processes alter this communication. In the past, such analyses have usually been based on single or paired sections obtained by electron microscopy. Reconstruction from multiple serial sections provides a much needed, richer representation of the three-dimensional organization of the brain. This paper introduces a new reconstruction system and new methods for analyzing in three dimensions the location and ultrastructure of neuronal components, such as synapses, which are distributed non-randomly throughout the brain. DESIGN AND MEASUREMENTS: Volumes are reconstructed by defining transformations that align the entire area of adjacent sections. Whole-field alignment requires rotation, translation, skew, scaling, and second-order nonlinear deformations. Such transformations are implemented by a linear combination of bivariate polynomials. Computer software for generating transformations based on user input is described. Stereological techniques for assessing structural distributions in reconstructed volumes are the unbiased bricking, disector, unbiased ratio, and per-length counting techniques. A new general method, the fractional counter, is also described. This unbiased technique relies on the counting of fractions of objects contained in a test volume. A volume of brain tissue from stratum radiatum of hippocampal area CA1 is reconstructed and analyzed for synaptic density to demonstrate and compare the techniques. RESULTS AND CONCLUSIONS: Reconstruction makes practicable volume-oriented analysis of ultrastructure using such techniques as the unbiased bricking and fractional counter methods. These analysis methods are less sensitive to the section-to-section variations in counts and section thickness, factors that contribute to the inaccuracy of other stereological methods. In addition, volume reconstruction facilitates visualization and modeling of structures and analysis of three-dimensional relationships such as synaptic connectivity.

Fiala, J. C.; Harris, K. M.; Koslow, S. H. (Principal Investigator)

2001-01-01

116

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

SciTech Connect

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

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

2011-03-15

117

The Modified Best Quadratic Unbiased NonNegative Estimator (MBQUNE) of variance components  

Microsoft Academic Search

Estimated variance components may come out as negative numbers without physical meaning. One way out of this problem is to\\u000a use non-negative methods. Different approaches have been presented for the solution. Sjöberg presented a method of Best Quadratic\\u000a Unbiased Non-Negative Estimator (BQUNE) in the Gauss-Helmert model. This estimator does not exist in the general case. Here\\u000a we present the Modified

M. Eshagh; L. E. Sjöberg

2008-01-01

118

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

E-print Network

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.

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

2015-02-04

119

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

PubMed Central

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

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

2014-01-01

120

C NMR Spectra C NMR Spectra  

E-print Network

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

Collum, David B.

121

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

NASA Astrophysics Data System (ADS)

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.

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

122

Nanostructured polystyrene well plates allow unbiased high-throughput characterization of circulating tumor cells.  

PubMed

Rapid, reliable and unbiased circulating tumor cell (CTC) isolation and molecular characterization methods are urgently required for implementation in routine clinical diagnostic and prognostic procedures. We report on the development of a novel unbiased CTC detection approach that combines high-throughput automated microscopy with a simple yet efficient approach for achieving a high level of tumor cell binding in standard tissue culture polystyrene (PS) well plates. A single 5 min high-power oxygen plasma treatment was used to create homogeneous nanoscale roughness on standard PS tissue culture plates and, in turn, drastically enhance the binding of a range of tumor cells. After physical adsorption of an adlayer of poly-l-lysine, binding yields above 97% were obtained at 2 h for all tumor cell lines used in the study. Morphological analysis of the cells confirmed strong adherence to the nanorough PS substrates. Clinically relevant concentrations of a highly metastatic breast cancer cell line, used as model for CTCs, could be reliably detected among blood cells on the nanorough polystyrene plates using an automated microscopy system. The approach was then successfully used to detect CTCs in the blood of a stage IIIc colorectal cancer patient. By combining the high binding abilities of nanorough PS well plates with the high-throughput nature of high-content analysis systems, this methodology has great potential toward enabling unbiased routine clinical analysis of CTCs. It could be applied, once clinically validated, in any clinical center equipped with an automated microscopy facility at a fraction of the cost of current CTC isolation technologies. PMID:25366695

Wan, Yuan; Winter, Marnie; Delalat, Bahman; Hardingham, Jennifer E; Grover, Phulwinder K; Wrin, Joseph; Voelcker, Nicolas H; Price, Timothy J; Thierry, Benjamin

2014-12-10

123

Tables for unbiased confidence intervals for ratios of variances when sampling from two independent normal distributions  

Microsoft Academic Search

Tables are given for the upper tail values for unbiased confidence intervals for ratios of variances when sampling from two independent normal distributions for sample sizes (N1-l) = 1(1)20(5)30(30)60(60)120 and (N2?l) = 1(1)30(5)40(20)60(60)120, and alpha levels of 0.10,0.05,0.01 (where the alpha level is the sum of the upper and lower tail areas). These confidence intervals are logarithmically shortest confidence intervals,

J. E. Scholz; D. R. Barr

1973-01-01

124

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

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

125

On the Impossibility to Extend Triples of Mutually Unbiased Product Bases in Dimension Six  

E-print Network

An analytic proof is given which shows that it is impossible to extend any triple of mutually unbiased (MU) product bases in dimension six by a single MU vector. Furthermore, the 16 states obtained by removing two orthogonal states from any MU product triple cannot figure in a (hypothetical) complete set of seven MU bases. These results follow from exploiting the structure of MU product bases in a novel fashion, and they are among the strongest ones obtained for MU bases in dimension six without recourse to computer algebra.

Daniel McNulty; Stefan Weigert

2012-10-01

126

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

PubMed

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

Clark, Samuel A; van der Werf, Julius

2013-01-01

127

Relative risk estimated from the ratio of two median unbiased estimates  

PubMed Central

Clinical trials often include binary endpoints. In some cases, no successes are observed and the usual large-sample estimates of relative risk are undefined. This paper proposes an estimator for relative risk based on the median unbiased estimator. The proposed relative risk estimator is well defined and performs satisfactorily for a wide range of data configurations. To facilitate the use of the estimator, a deterministic bootstrap confidence interval is also proposed, and a SAS MACRO is available to perform the necessary calculations. An ongoing randomized clinical trial motivated the development of the estimator and is used to illustrate the approach. PMID:20711511

Carter, Rickey E.; Lin, Yan; Lipsitz, Stuart R.; Newcombe, Robert G.; Hermayer, Kathie L.

2010-01-01

128

Human systems immunology: hypothesis-based modeling and unbiased data-driven approaches  

PubMed Central

Systems immunology is an emerging paradigm that aims at a more systematic and quantitative understanding of the immune system. Two major approaches have been utilized to date in this field: unbiased data-driven modeling to comprehensively identify molecular and cellular components of a system and their interactions; and hypothesis-based quantitative modeling to understand the operating principles of a system by extracting a minimal set of variables and rules underlying them. In this review, we describe applications of the two approaches to the study of viral infections and autoimmune diseases in humans, and discuss possible ways by which these two approaches can synergize when applied to human immunology. PMID:23375135

Arazi, Arnon; Pendergraft, William F.; Ribeiro, Ruy M.; Perelson, Alan S.; Hacohen, Nir

2013-01-01

129

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

PubMed

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

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

2011-08-01

130

An Unbiased Method for Clustering Bacterial Effectors Using Host Cellular Phenotypes  

PubMed Central

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

Hodgson, David J.

2014-01-01

131

Construction of mutually unbiased bases with cyclic symmetry for qubit systems  

SciTech Connect

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

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

2011-10-15

132

Weighted skewness and kurtosis unbiased by sample size and Gaussian uncertainties  

NASA Astrophysics Data System (ADS)

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

Rimoldini, Lorenzo

2014-07-01

133

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

E-print Network

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

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

2015-01-01

134

Estimating unbiased economies of scale of HIV prevention projects: A case study of Avahan.  

PubMed

Governments and donors are investing considerable resources on HIV prevention in order to scale up these services rapidly. Given the current economic climate, providers of HIV prevention services increasingly need to demonstrate that these investments offer good 'value for money'. One of the primary routes to achieve efficiency is to take advantage of economies of scale (a reduction in the average cost of a health service as provision scales-up), yet empirical evidence on economies of scale is scarce. Methodologically, the estimation of economies of scale is hampered by several statistical issues preventing causal inference and thus making the estimation of economies of scale complex. In order to estimate unbiased economies of scale when scaling up HIV prevention services, we apply our analysis to one of the few HIV prevention programmes globally delivered at a large scale: the Indian Avahan initiative. We costed the project by collecting data from the 138 Avahan NGOs and the supporting partners in the first four years of its scale-up, between 2004 and 2007. We develop a parsimonious empirical model and apply a system Generalized Method of Moments (GMM) and fixed-effects Instrumental Variable (IV) estimators to estimate unbiased economies of scale. At the programme level, we find that, after controlling for the endogeneity of scale, the scale-up of Avahan has generated high economies of scale. Our findings suggest that average cost reductions per person reached are achievable when scaling-up HIV prevention in low and middle income countries. PMID:25779621

Lépine, Aurélia; Vassall, Anna; Chandrashekar, Sudha; Blanc, Elodie; Le Nestour, Alexis

2015-04-01

135

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

PubMed

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

Shmaliy, Yuriy S

2006-05-01

136

Denoising PET images using singular value thresholding and Stein's unbiased risk estimate.  

PubMed

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

Bagci, Ulas; Mollura, Daniel J

2013-01-01

137

Qudits of composite dimension, mutually unbiased bases and projective ring geometry  

E-print Network

The $d^2$ Pauli operators attached to a composite qudit in dimension $d$ may be mapped to the vectors of the symplectic module $\\mathcal{Z}_d^{2}$ ($\\mathcal{Z}_d$ the modular ring). As a result, perpendicular vectors correspond to commuting operators, a free cyclic submodule to a maximal commuting set, and disjoint such sets to mutually unbiased bases. For dimensions $d=6,~10,~15,~12$, and 18, the fine structure and the incidence between maximal commuting sets is found to reproduce the projective line over the rings $\\mathcal{Z}_{6}$, $\\mathcal{Z}_{10}$, $\\mathcal{Z}_{15}$, $\\mathcal{Z}_6 \\times \\mathbf{F}_4$ and $\\mathcal{Z}_6 \\times \\mathcal{Z}_3$, respectively.

Michel Planat; Anne-Céline Baboin

2007-10-10

138

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

NASA Technical Reports Server (NTRS)

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

Johnson, H. M.

1986-01-01

139

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

140

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

NASA Astrophysics Data System (ADS)

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

Malkan, M.; WISP Team

2013-10-01

141

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

NASA Astrophysics Data System (ADS)

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.

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

2015-03-01

142

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

PubMed

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

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

2012-08-01

143

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

PubMed

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

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

2015-01-01

144

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

NASA Technical Reports Server (NTRS)

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

Johnson, H. M.

1985-01-01

145

Mutually unbiased bases: tomography of spin states and star-product scheme  

E-print Network

Mutually unbiased bases (MUBs) are considered within the framework of a generic star-product scheme. We rederive that a full set of MUBs is adequate for a spin tomography, i.e. knowledge of all probabilities to find a system in each MUB-state is enough for a state reconstruction. Extending the ideas of the tomographic-probability representation and the star-product scheme to MUB-tomography, dequantizer and quantizer operators for MUB-symbols of spin states and operators are introduced, ordinary and dual star-product kernels are found. Since MUB-projectors are to obey specific rules of the star-product scheme, we reveal the Lie algebraic structure of MUB-projectors and derive new relations on triple- and four-products of MUB-projectors. Example of qubits is considered in detail. MUB-tomography by means of Stern-Gerlach apparatus is discussed.

S. N. Filippov; V. I. Man'ko

2010-08-16

146

Optical Spectra of Supernovae  

E-print Network

Supernova flux and polarization spectra bring vital information on the geometry, physical conditions, and composition structure of the ejected matter. For some supernovae the circumstellar matter is also probed by the observed spectra. Some of this information can be inferred directly from the observed line profiles and fluxes, but because of the Doppler broadening and severe line blending, interpretation often involves the use of synthetic spectra. The emphasis in this Chapter is on recent results obtained with the help of synthetic spectra.

David Branch; E. Baron; David J. Jeffery

2001-11-30

147

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

Microsoft Academic Search

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

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

1998-01-01

148

Combination of an unbiased amplification method and a resequencing microarray for detecting and genotyping equine arteritis virus.  

PubMed

This study shows that an unbiased amplification method applied to equine arteritis virus RNA significantly improves the sensitivity of the real-time reverse transcription-quantitative PCR (RT-qPCR) recommended by the World Organization for Animal Health. Twelve viral RNAs amplified using this method were hybridized on a high-density resequencing microarray for effective viral characterization. PMID:25339390

Hans, Aymeric; Gaudaire, Delphine; Manuguerra, Jean-Claude; Leon, Albertine; Gessain, Antoine; Laugier, Claire; Berthet, Nicolas; Zientara, Stephan

2015-01-01

149

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

SciTech Connect

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

Combescure, Monique [IPNL, CNRS, 4 rue Enrico Fermi, Villeurbanne F-69622 (France)

2009-03-15

150

The Importance of Validating the Duration of Fishing Trips: Are Harvest Rates from On-Site Recreational Fishing Surveys Unbiased?  

Microsoft Academic Search

Harvest rates are often used as indicators of fishing quality and in the estimation of total harvest in some on-site survey designs. The unbiased estimation of harvest and fishing effort is critical for calculating accurate harvest rates. On-site survey designs allow survey clerks to validate harvest data directly. This harvest validation assumes that the level of intentional deception by fishers

Aldo S. Steffe; Jeffrey J. Murphy

2010-01-01

151

Statistical Properties of Maximum Likelihood Estimators of Power Law Spectra Information  

NASA Technical Reports Server (NTRS)

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

Howell, L. W., Jr.

2003-01-01

152

Hybrid Estimation of CMB Polarization Power Spectra  

E-print Network

This paper generalises the hybrid power spectrum estimator developed in Efstathiou (2004a) to the estimation of polarization power spectra of the cosmic microwave background radiation. The hybrid power spectrum estimator is unbiased and we show that it is close to optimal at all multipoles, provided the pixel noise satisfies certain reasonable constraints. Furthermore, the hybrid estimator is computationally fast and can easily be incorporated in a Monte-Carlo chain for Planck-sized data sets. Simple formulae are given for the covariance matrices, including instrumental noise, and these are tested extensively against numerical simulations. We compare the behaviour of simple pseudo-Cell estimates with maximum likelihood estimates at low multipoles. For realistic sky cuts, maximum likelihood estimates reduce very significantly the mixing of E and B modes. To achieve limits on the scalar-tensor ratio of r<<0.1 from sky maps with realistic sky cuts, maximum likelihood methods, or pseudo-Cell estimators based on unambiguous E and B modes, will be essential.

G. Efstathiou

2006-01-05

153

Crack spectra analysis  

SciTech Connect

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

Tiernan, M.

1980-09-01

154

The First Unbiased Radio Emission Line Survey of the Protoplanetary Disk Orbiting Lkca 15  

NASA Astrophysics Data System (ADS)

We have conducted the first comprehensive mm-wave molecular emission line survey of the circumstellar disk orbiting the nearby, pre-main sequence (T Tauri) star LkCa 15 (D = 140 pc). The outer disk is chemically rich, with numerous previous detections of molecular emission lines revealing a significant gas mass. The disk around this young (˜3-5 Myr), actively accreting solar analog likely hosts a young protoplanet (LkCa 15b) within its central cavity. Hence, LkCa 15 is an excellent target for an unbiased radio spectroscopic survey intended to produce a full census of the detectable molecular species within an evolved, protoplanetary disk. Our survey of LkCa 15 was conducted with the Institute de Radioastronomie Millimétrique (IRAM) 30 meter telescope over the 1.1-1.4 mm wavelength range. The survey includes detections of the three most abundant CO isotopologues (12CO, 13CO, and C18O) which facilitate estimates of the spatially integrated CO emission line optical depths, and complete coverage of the hyperfine line complexes of CN and C2H that provide diagnostics of excitation and opacity for these species. This work demonstrates the value of comprehensive single-dish line surveys in guiding future high resolution interferometric imaging by ALMA of protoplanetary disks orbiting T Tauri stars.

Punzi, Kristina Marie; Kastner, Joel H.; Hily-Blant, Pierre; Forveille, Thierry; Sacco, G. G.

2014-06-01

155

Collision energy alteration during mass spectrometric acquisition is essential to ensure unbiased metabolomic analysis.  

PubMed

Metabolomics entails identification and quantification of all metabolites within a biological system with a given physiological status; as such, it should be unbiased. A variety of techniques are used to measure the metabolite content of living systems, and results differ with the mode of data acquisition and output generation. LC-MS is one of many techniques that has been used to study the metabolomes of different organisms but, although used extensively, it does not provide a complete metabolic picture. Recent developments in technology, for example the introduction of UPLC-ESI-MS, have, however, seen LC-MS become the preferred technique for metabolomics. Here, we show that when MS settings are varied in UPLC-ESI-MS, different metabolite profiles result from the same sample. During use of a Synapt UPLC-high definition MS instrument, the collision energy was continually altered (3, 10, 20, and 30 eV) during MS acquisition. PCA and OPLS-DA analysis of the generated UPLC-MS data of metabolites extracted from elicited tobacco cells revealed different clustering and different distribution patterns. As expected, ion abundance decreases with increasing collision energy, but, more importantly, results in unique multivariate data patterns from the same samples. Our findings suggest that different collision energy settings should be investigated during MS data acquisition because these can contribute to coverage of a wider range of the metabolome by UPLC-ESI-MS and prevent biased results. PMID:22699233

Madala, Ntakadzeni E; Steenkamp, Paul A; Piater, Lizelle A; Dubery, Ian A

2012-08-01

156

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

PubMed Central

We report a rhodium catalyst that exhibits high reactivity for the hydroamination of primary aminoalkenes that are unbiased toward cyclization and that possess functional groups that would not be tolerated in hydroaminations catalyzed by more electrophilic systems. This catalyst contains an unusual diaminophosphine ligand that binds to rhodium in a ?3-P,O,P mode. The reactions catalyzed by this complex typically proceed at mild temperatures (room temperature to 70 °C), occur with primary aminoalkenes lacking substituents on the alkyl chain that bias the system toward cyclization, occur with primary aminoalkenes containing chloride, ester, ether, enolizable ketone, nitrile, and unprotected alcohol functionality, and occur with primary aminoalkenes containing internal olefins. Mechanistic data imply that these reactions occur with a turnover-limiting step that is different from that of reactions catalyzed by late transition metal complexes of Pd, Pt, and Ir. This change in the turnover-limiting step and resulting high activity of the catalyst stem from favorable relative rates for protonolysis of the M-C bond to release the hydroamination product vs reversion of the aminoalkyl intermediate to regenerate the acyclic precursor. Probes for the origin of the reactivity of the rhodium complex of L1 imply that the aminophosphine groups lead to these favorable rates by effects beyond steric demands and simple electron donation to the metal center. PMID:20839807

Julian, Lisa D.; Hartwig, John F.

2010-01-01

157

Unbiased compound screening identifies unexpected drug sensitivities and novel treatment options for gastrointestinal stromal tumors.  

PubMed

Most gastrointestinal stromal tumors (GIST) are caused by oncogenic KIT or platelet-derived growth factor receptor activation, and the small molecule kinase inhibitor imatinib mesylate is an effective first-line therapy for metastatic or unresectable GIST. However, complete remissions are rare and most patients ultimately develop resistance, mostly because of secondary mutations in the driver oncogenic kinase. Hence, there is a need for novel treatment options to delay failure of primary treatment and restore tumor control in patients who progress under therapy with targeted agents. Historic data suggest that GISTs do not respond to classical chemotherapy, but systematic unbiased screening has not been performed. In screening a compound library enriched for U.S. Food and Drug Administration (FDA)-approved chemotherapeutic agents (NCI Approved Oncology Drugs Set II), we discovered that GIST cells display high sensitivity to transcriptional inhibitors and topoisomerase II inhibitors. Mechanistically, these compounds exploited the cells' dependency on continuous KIT expression and/or intrinsic DNA damage response defects, explaining their activity in GIST. Mithramycin A, an indirect inhibitor of the SP1 transcription factor, and mitoxantrone, a topoisomerase II inhibitor, exerted significant antitumor effects in mouse xenograft models of human GIST. Moreover, these compounds were active in patient-derived imatinib-resistant primary GIST cells, achieving efficacy at clinically relevant concentrations. Taken together, our findings reveal that GIST cells have an unexpectedly high and specific sensitivity to certain types of FDA-approved chemotherapeutic agents, with immediate implications for encouraging their clinical exploration. PMID:24385214

Boichuk, Sergei; Lee, Derek J; Mehalek, Keith R; Makielski, Kathleen R; Wozniak, Agnieszka; Seneviratne, Danushka S; Korzeniewski, Nina; Cuevas, Rolando; Parry, Joshua A; Brown, Matthew F; Zewe, James; Taguchi, Takahiro; Kuan, Shin-Fan; Schöffski, Patrick; Debiec-Rychter, Maria; Duensing, Anette

2014-02-15

158

Unbiased expression of FRF with exponential window function in impact hammer testing  

NASA Astrophysics Data System (ADS)

The exponential window function is widely used in impact hammer testing to reduce leakage errors as well as to get a nice S/N ratio. The larger the exponential decay rate of the window is, the more effectively the leakage errors are reduced. But if the decay rate of the exponential window function is too large, the frequency response function (FRF) is distorted by its side effects. The modal parameters of the system cannot be exactly identified from the distorted FRF even though modal analysis technique is used. Therefore, it is a difficult problem to determine a proper exponential decay rate in an impact hammer testing. In this paper, the amount of the FRF distortion caused by the exponential window function is theoretically uncovered, and an unbiased expression of the exponential-windowed FRF is represented. A new circle fitting method is also proposed so that the modal parameters are directly extracted from the impulse response spectrum distorted by the exponential window function. The results identified by the conventional and proposed circle fitting method are compared through numerical examples.

Ahn, Se Jin; Jeong, Weui Bong; Yoo, Wan Suk

2004-11-01

159

Unbiased Feature Selection in Learning Random Forests for High-Dimensional Data  

PubMed Central

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

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

2015-01-01

160

P7C3 and an unbiased approach to drug discovery for neurodegenerative diseases  

PubMed Central

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

McKnight, Steven L.; Ready, Joseph M.

2014-01-01

161

Unbiased estimation of gene diversity in samples containing related individuals: exact variance and arbitrary ploidy.  

PubMed

Gene diversity, a commonly used measure of genetic variation, evaluates the proportion of heterozygous individuals expected at a locus in a population, under the assumption of Hardy-Weinberg equilibrium. When using the standard estimator of gene diversity, the inclusion of related or inbred individuals in a sample produces a downward bias. Here, we extend a recently developed estimator shown to be unbiased in a diploid autosomal sample that includes known related or inbred individuals to the general case of arbitrary ploidy. We derive an exact formula for the variance of the new estimator, H, and present an approximation to facilitate evaluation of the variance when each individual is related to at most one other individual in a sample. When examining samples from the human X chromosome, which represent a mixture of haploid and diploid individuals, we find that H performs favorably compared to the standard estimator, both in theoretical computations of mean squared error and in data analysis. We thus propose that H is a useful tool in characterizing gene diversity in samples of arbitrary ploidy that contain related or inbred individuals. PMID:20923981

DeGiorgio, Michael; Jankovic, Ivana; Rosenberg, Noah A

2010-12-01

162

Metabolic profiling in Caenorhabditis elegans provides an unbiased approach to investigations of dosage dependent lead toxicity.  

PubMed

The nematode, Caenorhabditis elegans (CE), serves as a model system in which to explore the impact of particularly low-levels of lead [250, 500, 1000 and 2000 parts per million (ppm) (1.4 × 10(-6) M to 1.1 × 10(-5) M/nematode)] on specific metabolic pathways and processes. Chromatographic profiles of redox active metabolites are captured through application of high performance liquid chromatography coupled to electrochemical detection (Coularray/HPLC). Principal Component Analysis (PCA: unbiased cluster analysis) and the application of a slicing program, located significant areas of difference occurring within the 2.8-4.58 min section of the chromatograms. It is within this region of the data profiles that known components of the purine pathway reside. Two analytes of unknown structure were detected at 3.5 and 4 min respectively. Alterations in levels of the purine, tryptophan and tyrosine pathway intermediates measured in response to differing concentrations of lead acetate indicate that the effect of lead on these pathways is not linear, yet the ratio of the pathway precursors, tryptophan and tyrosine remains relatively constant. The application of the above combined analytical approaches enhances the value of data generated. Exposure of CE to very low levels of lead produced significant alterations in profiles of electrochemically active compounds. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11306-012-0438-0) contains supplementary material, which is available to authorized users. PMID:23335868

Sudama, Gita; Zhang, John; Isbister, Jenefir; Willett, James D

2013-02-01

163

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

164

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

SciTech Connect

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

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

2013-07-20

165

Myths and Truths Concerning Estimation of Power Spectra  

E-print Network

It is widely believed that maximum likelihood estimators must be used to provide optimal estimates of power spectra. Since such estimators require require of order N_d^3 operations they are computationally prohibitive for N_d greater than a few tens of thousands. Because of this, a large and inhomogeneous literature exists on approximate methods of power spectrum estimation. These range from manifestly sub-optimal, but computationally fast methods, to near optimal but computationally expensive methods. Furthermore, much of this literature concentrates on the power spectrum estimates rather than the equally important problem of deriving an accurate covariance matrix. In this paper, I consider the problem of estimating the power spectrum of cosmic microwave background (CMB) anisotropies from large data sets. Various analytic results on power spectrum estimators are derived, or collated from the literature, and tested against numerical simulations. An unbiased hybrid estimator is proposed that combines a maximum...

Efstathiou, G P

2004-01-01

166

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

PubMed

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

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

2014-09-01

167

Optical Spectra of Supernovae  

Microsoft Academic Search

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

Alexei V. Filippenko

1997-01-01

168

The minimum spanning tree: an unbiased method for brain network analysis.  

PubMed

The brain is increasingly studied with graph theoretical approaches, which can be used to characterize network topology. However, studies on brain networks have reported contradictory findings, and do not easily converge to a clear concept of the structural and functional network organization of the brain. It has recently been suggested that the minimum spanning tree (MST) may help to increase comparability between studies. The MST is an acyclic sub-network that connects all nodes and may solve several methodological limitations of previous work, such as sensitivity to alterations in connection strength (for weighted networks) or link density (for unweighted networks), which may occur concomitantly with alterations in network topology under empirical conditions. If analysis of MSTs avoids these methodological limitations, understanding the relationship between MST characteristics and conventional network measures is crucial for interpreting MST brain network studies. Here, we firstly demonstrated that the MST is insensitive to alterations in connection strength or link density. We then explored the behavior of MST and conventional network-characteristics for simulated regular and scale-free networks that were gradually rewired to random networks. Surprisingly, although most connections are discarded during construction of the MST, MST characteristics were equally sensitive to alterations in network topology as the conventional graph theoretical measures. The MST characteristics diameter and leaf fraction were very strongly related to changes in the characteristic path length when the network changed from a regular to a random configuration. Similarly, MST degree, diameter, and leaf fraction were very strongly related to the degree of scale-free networks that were rewired to random networks. Analysis of the MST is especially suitable for the comparison of brain networks, as it avoids methodological biases. Even though the MST does not utilize all the connections in the network, it still provides a, mathematically defined and unbiased, sub-network with characteristics that can provide similar information about network topology as conventional graph measures. PMID:25451472

Tewarie, P; van Dellen, E; Hillebrand, A; Stam, C J

2015-01-01

169

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

PubMed Central

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

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

2012-01-01

170

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

PubMed Central

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

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

2015-01-01

171

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

PubMed Central

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

Kubínová, Zuzana

2014-01-01

172

Unbiased feature selection through successive elimination of poor performers for EEG classification  

NASA Astrophysics Data System (ADS)

Electroencephalogram (EEG) pattern recognition problem is considered as a composite of three subproblems: feature extraction, feature selection, and pattern classification. Focusing particularly on the feature selection issue, each subproblem is reviewed briefly and a new method for feature selection is proposed. The method suggests that first one shall extract as much information (features) as conveniently possible in several pattern information domains and then apply the proposed unbiased successive feature elimination process to remove redundant and poor features. From this set select a significantly smaller, yet useful, feature subset that enhances the performance of the classifier. The successive feature elimination process is formally described. The method is successfully applied to an EEG signal classification problem. The features selected by the algorithm are used to classify three signal classes. The classes identified were eye artifacts, muscle artifacts, and clean (subject in stationary state). Two hundred samples for each of the three classes were selected and the data set was arbitrarily divided into two subsets: design subset, and testing subset. A proximity index classifier using Mahalanobis distance as the proximity criterion was developed using the smaller feature subset. The system was trained on the design set. The recognition performance on the design set was 92.33%. The recognition performance on the testing set was 88.67% by successfully identifying the samples in eye-blinks, muscle response, and clean classes, respectively, with 80%, 97%, and 89%. This performance is very encouraging. In addition, the method is computationally inexpensive and particularly useful for large data set problems. The method further reduces the need for a careful feature determination problem that a system designer usually encounters during the initial design phase of a pattern classifier.

Siddiqui, Khalid J.

1996-04-01

173

Amp-PCR: Combining a Random Unbiased Phi29Amplification with a Specific Real-Time PCR, Performed in One Tube to Increase PCR Sensitivity  

Microsoft Academic Search

In clinical situations where a diagnostic real-time PCR assay is not sensitive enough, leading to low or falsely negative results, or where detection earlier in a disease progression would benefit the patient, an unbiased pre-amplification prior to the real-time PCR could be beneficial. In Amp-PCR, an unbiased random Phi29 pre-amplification is combined with a specific real-time PCR reaction. The two

Lena Erlandsson; Lars Peter Nielsen; Anders Fomsgaard

2010-01-01

174

Assessing diet-health relationships using a short-term unbiased dietary instrument: focus on risk models with multiple dietary components  

Cancer.gov

Identify challenges in estimating relationships between a dietary exposure measured by repeated application of a short-term unbiased instrument and a health outcome in a risk model with multiple dietary components. Describe potential approaches to correct for within-person random measurement error in estimating relationships between a dietary exposure measured by a short-term unbiased instrument and a health outcome in a risk model with multiple dietary components.

175

it is an unbiased, universal detector," says Jack Newton, a product manager at Chenomx in  

E-print Network

for a project that would marry Fiehn's expertise in metabolomics and her interest in wine. "There are so many and then ran samples on a LECO Pegasus IV GC TOF MS system and analysed the spectra using the BinBase program

Cai, Long

176

Quasi-linear least squares and computer code for numerical evaluation of relaxation time distribution from broadband dielectric spectra.  

PubMed

We present a new fitting procedure and computer code for numerical evaluation of dielectric relaxation time distribution functions. The technique is based on linear least squares minimization and aims primarily at the analysis of compound experimental spectra of complex dielectric permittivity. It is fast, robust, and easy to use. No prior knowledge about the number of relaxation modes, their characteristic times, relaxation strengths, or the functional form of the underlying relaxation time distribution function is required, the procedure determines these parameters instead. The method is tested by both synthetic spectra with well-defined parameters of dielectric relaxation and experimental wide-band dielectric spectra of different types. We believe that this new fitting instrument, which allows an unbiased approach to the formal description of dielectric spectra, may be of interest in many areas of dielectric spectroscopy. PMID:21406849

Zasetsky, A Y; Buchner, R

2011-01-19

177

PAH Spectra for Everyone  

NASA Astrophysics Data System (ADS)

The Ames Astrochemistry Laboratory now has PAH IR spectra of more than 220 laboratory measured and over 600 theoretically calculated IR spectra of polycyclic aromatic hydrocarbons (PAHs) in a multitude of forms. The vast majority of these spectra are not readily accessible to the public. We propose to make the full collection of the Ames experimental and computational collection of PAH IR spectra available to the entire Spitzer community and accessible via the World Wide Web (WWW). The laboratory measured mid-IR spectral collection includes over 220 neutral, cationic, and anionic PAHs, PAHs with deuterium in place of hydrogen, PAHs containing oxygen, and PAHs containing nitrogen (PANHs). The formulae of the PAHs in the experimental data collection range from C10H8 to C50H22. Unfortunately, it is not possible to obtain physical samples of all of the types of PAHs that are of astrophysical interest for experimental study. We also have an extensive collection of accurate computational spectra to fill in gaps in the experimentally available spectra. Our theoretical PAH spectral collection includes very large PAHs, PAHs containing 40 to 132 carbon atoms which are comparable to the size of the PAHs thought to dominate the interstellar emission spectrum. Large PAHs might be multiply charged and these are also represented in the theoretical database. There is also observational evidence for PAH cations with nitrogen in the inner rings (PANHs) and interest in the spectroscopy of aromatic species containing oxygen and deuterium as well as PAH metal clusters. All of these types of PAHs are represented in the Ames computational PAH IR spectroscopic collection. If funded, we plan to make our entire inventory of the lab spectra available to the Spitzer community within the next two years.

Allamandola, Louis; Bauschlicher, Charlie, Jr.; Mattioda, Andrew

2007-05-01

178

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

PubMed Central

Neurodegenerative diseases, such as multiple sclerosis represent global health issues. Accordingly, there is an urgent need to understand the pathogenesis of this and other central nervous system disorders, so that more effective therapeutics can be developed. Cerebrospinal fluid is a potential source of important reporter molecules released from various cell types as a result of central nervous system pathology. Here, we report the development of an unbiased approach for the detection of reactive cerebrospinal fluid molecules and target brain proteins from patients with multiple sclerosis. To help identify molecules that may serve as clinical biomarkers for multiple sclerosis, we have biotinylated proteins present in the cerebrospinal fluid and tested their reactivity against brain homogenate as well as myelin and myelin-axolemmal complexes. Proteins were separated by two-dimensional gel electrophoresis, blotted onto membranes and probed separately with biotinylated unprocessed cerebrospinal fluid samples. Protein spots that reacted to two or more multiple sclerosis-cerebrospinal fluids were further analyzed by matrix assisted laser desorption ionization-time-of-flight time-of-flight mass spectrometry. In addition to previously reported proteins found in multiple sclerosis cerebrospinal fluid, such as ?? crystallin, enolase, and 14–3-3-protein, we have identified several additional molecules involved in mitochondrial and energy metabolism, myelin gene expression and/or cytoskeletal organization. These include aspartate aminotransferase, cyclophilin-A, quaking protein, collapsin response mediator protein-2, ubiquitin carboxy-terminal hydrolase L1, and cofilin. To further validate these findings, the cellular expression pattern of collapsin response mediator protein-2 and ubiquitin carboxy-terminal hydrolase L1 were investigated in human chronic-active MS lesions by immunohistochemistry. The observation that in multiple sclerosis lesions phosphorylated collapsin response mediator protein-2 was increased, whereas Ubiquitin carboxy-terminal hydrolase L1 was down-regulated, not only highlights the importance of these molecules in the pathology of this disease, but also illustrates the use of our approach in attempting to decipher the complex pathological processes leading to multiple sclerosis and other neurodegenerative diseases. PMID:21421798

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

2011-01-01

179

Statistical Properties of Maximum Likelihood Estimators of Power Law Spectra Information  

NASA Technical Reports Server (NTRS)

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

Howell, L. W.

2002-01-01

180

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

PubMed

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

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

181

Atomic Spectra Database (ASD)  

National Institute of Standards and Technology Data Gateway

SRD 78 NIST Atomic Spectra Database (ASD) (Web, free access)   This database provides access and search capability for NIST critically evaluated data on atomic energy levels, wavelengths, and transition probabilities that are reasonably up-to-date. The NIST Atomic Spectroscopy Data Center has carried out these critical compilations.

182

Spectra of coronae  

Microsoft Academic Search

We introduce a new invariant, the coronal of a graph, and use it to compute the spectrum of the corona G?H of two graphs G and H. In particular, we show that this spectrum is completely determined by the spectra of G and H and the coronal of H. Previous work has computed the spectrum of a corona only in

Cam McLeman; Erin McNicholas

2011-01-01

183

Identification and characterization of Highlands J virus from a Mississippi sandhill crane using unbiased next-generation sequencing.  

PubMed

Advances in massively parallel DNA sequencing platforms, commonly termed next-generation sequencing (NGS) technologies, have greatly reduced time, labor, and cost associated with DNA sequencing. Thus, NGS has become a routine tool for new viral pathogen discovery and will likely become the standard for routine laboratory diagnostics of infectious diseases in the near future. This study demonstrated the application of NGS for the rapid identification and characterization of a virus isolated from the brain of an endangered Mississippi sandhill crane. This bird was part of a population restoration effort and was found in an emaciated state several days after Hurricane Isaac passed over the refuge in Mississippi in 2012. Post-mortem examination had identified trichostrongyliasis as the possible cause of death, but because a virus with morphology consistent with a togavirus was isolated from the brain of the bird, an arboviral etiology was strongly suspected. Because individual molecular assays for several known arboviruses were negative, unbiased NGS by Illumina MiSeq was used to definitively identify and characterize the causative viral agent. Whole genome sequencing and phylogenetic analysis revealed the viral isolate to be the Highlands J virus, a known avian pathogen. This study demonstrates the use of unbiased NGS for the rapid detection and characterization of an unidentified viral pathogen and the application of this technology to wildlife disease diagnostics and conservation medicine. PMID:24880070

Ip, Hon S; Wiley, Michael R; Long, Renee; Palacios, Gustavo; Shearn-Bochsler, Valerie; Whitehouse, Chris A

2014-09-01

184

Activity: Graphing Spectra  

NSDL National Science Digital Library

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

2007-02-03

185

Rock Outcrop Spectra  

NASA Technical Reports Server (NTRS)

The color image on the lower left shows a rock outcrop at Meridiani Planum, Mars. This image was taken by the panoramic camera on the Mars Exploration Rover Opportunity, looking north, and was acquired on the 4th sol, or martian day, of the rover's mission (Jan. 27, 2004). The yellow box outlines an area detailed in the top left image, which is a monochrome (single filter) image from the rover's panoramic camera. The top image uses solid colors to show several regions on or near the rock outcrop from which spectra were extracted: the dark soil above the outcrop (yellow), the distant horizon surface (aqua), a bright rock in the outcrop (green), a darker rock in the outcrop (red), and a small dark cobblestone (blue). Spectra from these regions are shown in the plot to the right.

2004-01-01

186

Leading neutron spectra  

E-print Network

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.

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

2006-05-27

187

Infrared spectra of Venus  

NASA Technical Reports Server (NTRS)

A historical account of observations of Venus and their interpretation is given. The major constituent of the atmosphere on Venus (CO2) was detected spectroscopically forty years ago, and minor constituents (CO, HF, HCl) have been found more recently. The infrared spectra also provide a means of studying the motions of her cloudly atmosphere. The composition of the clouds has been sought in the reflection spectrum of Venus, and some of the evidence for their nature is discussed.

Young, L. G.

1974-01-01

188

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

PubMed Central

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

2014-01-01

189

Theoretical Studies of Molecular Spectra  

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

190

IUE archived spectra  

NASA Technical Reports Server (NTRS)

The International Ultraviolet Explorer (IUE) Satellite has been in continuous operation since January 26, 1978. To date, approximately 65,000 spectra have been stored in an archive at Goddard Space Flight Center in Greenbelt, MD. A number of procedures have been generated to facilitate access to the data in the IUE spectral archive. This document describes the procedures which include on-line quick look of the displays, search of an observation data base for selected observations, and several methods for ordering data from the archive.

Sullivan, Edward C.; Bohlin, Ralph C.; Heap, Sara R.; West, Donald K.; Schmitz, Marion

1988-01-01

191

[Raman spectra of pyroxene].  

PubMed

By testing the Raman spectra of megacryst pyroxene, enstatite and diopside in terms of location, shape and intensity, the symmetries of the main spectral band of pyroxene and the vibration modes of Raman shift were identified. The spectral bands of corresponding ionic groups such as non-bridge oxygen Si-O- and bridge oxygen Si-O0, O-Si-O and M-O were assigned for vibrational mode. Through the change in the intensity of the spectral band in different section direction and the deficiency of some spectral bands, the orientation problem in mineral crystallography was preliminarily studied. PMID:20384128

Wang, Rong; Zhang, Bao-Min

2010-02-01

192

Stars and their Spectra  

NASA Astrophysics Data System (ADS)

1. Stars; 2. Atoms and spectra; 3. The spectral sequence; 4. The M stars: red supergiants to dwarfs; 5. Descending the staircase: class L; 6. The wet basement: class T; 7. The K stars: orange giants and brighter dwarfs; 8. Our Sun and its cousins: the G stars; 9. Class F: stars in transition; 10. The white stars of class A; 11. The B stars: beacons of the skies; 12. Class O: the head of the spectral sequence; 13. Extraordinary classes; 14. Journeys on the HR diagram; Star index; Subject index.

Kaler, James B.

2011-07-01

193

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

Microsoft Academic Search

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

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

1991-01-01

194

Reviewing Pulsar Spectra  

E-print Network

Problems solved? Pulsar research must be considered - 35 years after the detection of pulsars - a mature science, where the basic questions have been raised and discussed. One would hope that many if not all generic and important problems have found some kind of answer and that scientific work can concentrate now on specific details requiring more in depth investigation. We know, however, that this picture is not true. Even well studied areas did in the past not always lead to a general accepted model and some were investigated at the beginning with enthusiasm but left behind. This paper will concentrate on one narrow topic, pulsar radio spectra. It is the attempt to work out, what features are now generally accepted, but also what features are still in discussion after so many years of pulsar research. In this sense the paper will enlighten in a personal view those aspects which are still under discussion.

W. Sieber

2002-08-30

195

TDS spectra analysis  

NASA Astrophysics Data System (ADS)

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.

Tomková, E.

1996-05-01

196

4 -STELLAR SPECTRA The spectra of most stars are approximately  

E-print Network

classification criteria have been developed. For stars heavily obscured by dust, near-IR (1-2.5 µm) features1 4 - STELLAR SPECTRA The spectra of most stars are approximately blackbodies. The presence features indicated the luminosity L of the star, and Roman numerals were appended to indicate

Sitko, Michael L.

197

SpectraFactory.net: A Database of Molecular Model Spectra  

NASA Astrophysics Data System (ADS)

We present a homogeneous database of synthetic molecular absorption and emission spectra from the optical to mm wavelengths for a large range of temperatures and column densities relevant for various astrophysical purposes, but in particular for the analysis, identification, and first-order analysis of molecular bands in spectroscopic observations. All spectra are calculated in the LTE limit from several molecular line lists, and are presented at various spectral resolving powers corresponding to several specific instrument simulations. The database is available online at http://www.spectrafactory.net, where users can freely browse, search, display, and download the spectra. We describe how additional model spectra can be requested for (automatic) calculation and inclusion. The database already contains over half a million model spectra for 39 molecules (96 different isotopologues) over the wavelength range 350 nm-3 mm (?3-30000 cm-1).

Cami, J.; van Malderen, R.; Markwick, A. J.

2010-04-01

198

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

PubMed Central

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

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

2013-01-01

199

Unbiased next generation sequencing analysis confirms the existence of autosomal dominant Alport syndrome in a relevant fraction of cases.  

PubMed

The mode of inheritance of Alport syndrome (ATS) has long been controversial. In 1927, the disease was hypothesized as a dominant condition in which males were more severely affected than females. In 1990, it was considered an X-linked (XL) semidominant condition, due to COL4A5 mutations. Later on, a rare autosomal recessive (AR) form due to COL4A3/COL4A4 mutations was identified. An autosomal dominant (AD) form was testified more recently by the description of some large pedigrees but the real existence of this form is still questioned by many and its exact prevalence is unknown. The introduction of next generation sequencing (NGS) allowed us to perform an unbiased simultaneous COL4A3-COL4A4-COL4A5 analysis in 87 Italian families (273 individuals) with clinical suspicion of ATS. In 48 of them (55%), a mutation in one of the three genes was identified: the inheritance was XL semidominant in 65%, recessive in 4% and most interestingly AD in 31% (15 families). The AD form must therefore be seriously taken into account in all pedigrees with affected individuals in each generation. Furthermore, a high frequency of mutations (>50%) was shown in patients with only 1 or 2 clinical criteria, suggesting NGS as first-level analysis in cases with a clinical suspicion of ATS. PMID:24033287

Fallerini, C; Dosa, L; Tita, R; Del Prete, D; Feriozzi, S; Gai, G; Clementi, M; La Manna, A; Miglietti, N; Mancini, R; Mandrile, G; Ghiggeri, G M; Piaggio, G; Brancati, F; Diano, L; Frate, E; Pinciaroli, A R; Giani, M; Castorina, P; Bresin, E; Giachino, D; De Marchi, M; Mari, F; Bruttini, M; Renieri, A; Ariani, F

2014-09-01

200

A Comparison of 1D and 2D (Unbiased) Experimental Methods for Measuring CSAsolarDD Cross-Correlated Relaxation  

NASA Astrophysics Data System (ADS)

Conventional and enhanced 1D experiments and different NOESY experiments (the 2D unbiased method) were performed for measuring CSA/DD cross-correlated relaxation on trehalose, a compound which could be approximated as a spherical top, and on simple model compounds comprisingC3vsymmetry (CHCl3, triphenylsilane (TPSi)). The comparison gives experimental evidence for the equivalence of the methods within the limits of the two-spin approach. 1D data are evaluated with both the simple initial rate and the Redfield relaxation matrix approach. The 2D data are obtained from the so-called transfer matrix using the Perrin-Gipe eigenvalue/eigenvector method. For the improved performance of the 2D method, anX-filtered (HHH) NOESY is suggested at the natural abundance of13C (or other dilute, low ? species). Also, experimental parameters crucial for reliable CSA data are tested (e.g., the impact of insufficient relaxation delay). Error estimation is carried out for fair comparison of methods. Revised liquid state1H and13C (29Si) CSA data are presented for chloroform and TPSi.

Batta, Gy.; Kövér, K. E.; Kowalewski, J.

1999-01-01

201

Protein–RNA specificity by high-throughput principal component analysis of NMR spectra  

PubMed Central

Defining the RNA target selectivity of the proteins regulating mRNA metabolism is a key issue in RNA biology. Here we present a novel use of principal component analysis (PCA) to extract the RNA sequence preference of RNA binding proteins. We show that PCA can be used to compare the changes in the nuclear magnetic resonance (NMR) spectrum of a protein upon binding a set of quasi-degenerate RNAs and define the nucleobase specificity. We couple this application of PCA to an automated NMR spectra recording and processing protocol and obtain an unbiased and high-throughput NMR method for the analysis of nucleobase preference in protein–RNA interactions. We test the method on the RNA binding domains of three important regulators of RNA metabolism. PMID:25586222

Collins, Katherine M.; Oregioni, Alain; Robertson, Laura E.; Kelly, Geoff; Ramos, Andres

2015-01-01

202

Projecting Spectra for Classroom Investigations.  

ERIC Educational Resources Information Center

Describes an inexpensive spectrum projector that makes high-dispersion, high-efficiency diffraction gratings using a holographic process. Discusses classroom applications such as transmission spectra, absorption spectra, reflection characteristics of materials, color mixing, florescence and phosphorescence, and break up spectral colors. (MDH)

Sadler, Philip

1991-01-01

203

Two components in meteor spectra  

Microsoft Academic Search

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

Jiri Borovicka

1994-01-01

204

Minimum mean squared error (MSE) adjustment and the optimal Tykhonov–Phillips regularization parameter via reproducing best invariant quadratic uniformly unbiased estimates (repro-BIQUUE)  

Microsoft Academic Search

In a linear Gauss–Markov model, the parameter estimates from BLUUE (Best Linear Uniformly Unbiased Estimate) are not robust\\u000a against possible outliers in the observations. Moreover, by giving up the unbiasedness constraint, the mean squared error\\u000a (MSE) risk may be further reduced, in particular when the problem is ill-posed. In this paper, the ?-weighted S-homBLE (Best homogeneously Linear Estimate) is derived

Burkhard Schaffrin

2008-01-01

205

Automated analysis of stellar spectra  

NASA Astrophysics Data System (ADS)

Classical model-atmosphere analyses of stellar spectra usually begin by measuring equivalent widths, and then proceed into a loop in which 1) model spectra are calculated for a set of abundances and atmospheric parameters, and 2) observed and computed spectra are compared and corrections to the abundances and parameters are inferred. Automated techniques have been developed to automate the measurement of equivalent widths, and some or all parts in the analysis loop. However, in order to tackle the massive datasets provided by the new spectroscopic surveys with dedicated telescopes, it is necessary to make some radical changes. It is argued that future analyses of stellar spectra should abandon the use of equivalent widths, and rely on tables of synthetic spectra that can be either interpolated extremely fast in minimum-distance optimization methods or used for training genetic algorithms. Examples of ongoing projects involving high-dispersion stellar spectra for a small sample and low-dispersion spectra for a sample of tens of thousands of stars are described.

Allende Prieto, C.

2004-10-01

206

Turn-directed ?-? conformational transition of ?-syn12 peptide at different pH revealed by unbiased molecular dynamics simulations.  

PubMed

The transition from ?-helical to ?-hairpin conformations of ?-syn12 peptide is characterized here using long timescale, unbiased molecular dynamics (MD) simulations in explicit solvent models at physiological and acidic pH values. Four independent normal MD trajectories, each 2500 ns, are performed at 300 K using the GROMOS 43A1 force field and SPC water model. The most clustered structures at both pH values are ?-hairpin but with different turns and hydrogen bonds. Turn9-6 and four hydrogen bonds (HB9-6, HB6-9, HB11-4 and HB4-11) are formed at physiological pH; turn8-5 and five hydrogen bonds (HB8-5, HB5-8, HB10-3, HB3-10 and HB12-1) are formed at acidic pH. A common folding mechanism is observed: the formation of the turn is always before the formation of the hydrogen bonds, which means the turn is always found to be the major determinant in initiating the transition process. Furthermore, two transition paths are observed at physiological pH. One of the transition paths tends to form the most-clustered turn and improper hydrogen bonds at the beginning, and then form the most-clustered hydrogen bonds. Another transition path tends to form the most-clustered turn, and turn5-2 firstly, followed by the formation of part hydrogen bonds, then turn5-2 is extended and more hydrogen bonds are formed. The transition path at acidic pH is as the same as the first path described at physiological pH. PMID:23708094

Liu, Lei; Cao, Zanxia

2013-01-01

207

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

PubMed

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

Vyas, Seema; Heise, Lori

2014-11-01

208

Elemental Absorption and Emission Spectra  

NSDL National Science Digital Library

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

209

Analysis of photometric spectra of 17 meteors  

NASA Technical Reports Server (NTRS)

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

Millman, P. M.

1982-01-01

210

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

PubMed Central

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

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

2011-01-01

211

Myths and Truths Concerning Estimation of Power Spectra  

E-print Network

It is widely believed that maximum likelihood estimators must be used to provide optimal estimates of power spectra. Since such estimators require require of order N_d^3 operations they are computationally prohibitive for N_d greater than a few tens of thousands. Because of this, a large and inhomogeneous literature exists on approximate methods of power spectrum estimation. These range from manifestly sub-optimal, but computationally fast methods, to near optimal but computationally expensive methods. Furthermore, much of this literature concentrates on the power spectrum estimates rather than the equally important problem of deriving an accurate covariance matrix. In this paper, I consider the problem of estimating the power spectrum of cosmic microwave background (CMB) anisotropies from large data sets. Various analytic results on power spectrum estimators are derived, or collated from the literature, and tested against numerical simulations. An unbiased hybrid estimator is proposed that combines a maximum likelihood estimator at low multipoles and pseudo-C_\\ell estimates at high multipoles. The hybrid estimator is computationally fast, nearly optimal over the full range of multipoles, and returns an accurate and nearly diagonal covariance matrix for realistic experimental configurations (provided certain conditions on the noise properties of the experiment are satisfied). It is argued that, in practice, computationally expensive methods that approximate the N_d^3 maximum likelihood solution are unlikely to improve on the hybrid estimator, and may actually perform worse. The results presented here can be generalised to CMB polarization and to power spectrum estimation using other types of data, such as galaxy clustering and weak gravitational lensing.

G. Efstathiou

2004-03-01

212

QUALITATIVE INTERPRETATION OF GALAXY SPECTRA  

SciTech Connect

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

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

2012-09-10

213

AVIRIS spectra of California wetlands  

NASA Technical Reports Server (NTRS)

Spectral data gathered by the AVIRIS from wetlands in the Suisun Bay area of California on 13 October 1987 were analyzed. Spectra representing stands of numerous vegetation types (including Sesuvium verrucosum, Scirpus acutus and Scirpus californicus, Xanthium strumarium, Cynadon dactylon, and Distichlis spicata) and soil were isolated. Despite some defects in the data, it was possible to detect vegetation features such as differences in the location of the chlorophyll red absorption maximum. Also, differences in cover type spectra were evident in other spectral regions. It was not possible to determine if the observed features represent noise, variability in canopy architecture, or chemical constituents of leaves.

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

1988-01-01

214

Gallery of Planetary Nebula Spectra  

NASA Astrophysics Data System (ADS)

In the course of our abundance studies over the past decade we have accumulated more than 120 high-quality, medium resolution spectra of planetary nebulae (PNe) from 3600-9600 Å using the KPNO 2.1m Goldcam CCD spectrograph and the CTIO 1.5m RC spectrograph. Results have been published in, e.g., Kwitter & Henry (1998); Henry, Kwitter & Balick (2004); and Milingo et al. (2006). We have created this website as a place where the spectra are available for graphical display, and where PN atlas information and image links are tabulated. The URL is: http://oit.williams.edu/nebulae

Kwitter, Karen B.; Henry, Richard B. C.

215

Spectra of Irradiated Giant Planets  

NASA Astrophysics Data System (ADS)

As many as 101 extrasolar giant planets (EGPs) have been detected by radial-velocity techniques, but none has been detected directly by its own emission or by reflection of the light from its parent star. We review the current state-of-the-art in the theoretical modeling of the spectra of giant planets outside the solar system and the basic theory of EGP spectra and atmospheres. We are now entering a new era of planet discovery and measurement. This contribution is meant to communicate some of the excitement in the astronomical community as the hunt for these exotic and remarkable objects accelerates.

Burrows, Adam; Sudarsky, David

2002-11-01

216

Vibrational Spectra of ?-Aminobutyric Acid  

NASA Astrophysics Data System (ADS)

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

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

2008-11-01

217

Computer Simulation of NMR Spectra.  

ERIC Educational Resources Information Center

Describes a PASCAL computer program which provides interactive analysis and display of high-resolution nuclear magnetic resonance (NMR) spectra from spin one-half nuclei using a hard-copy or monitor. Includes general and theoretical program descriptions, program capability, and examples of its use. (Source for program/documentation is included.)…

Ellison, A.

1983-01-01

218

Classical Trajectories and Quantum Spectra  

NASA Technical Reports Server (NTRS)

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

Mielnik, Bogdan; Reyes, Marco A.

1996-01-01

219

The FUV spectra of starbursts  

NASA Astrophysics Data System (ADS)

Starbursts are a significant component of the present-day universe, and offer unique laboratories for both studying the processes that have regulated the formation and evolution of galaxies, and for testing models of high-mass stellar evolution. We propose to exploit the unique strengths of FUSE to obtain full-resolution (˜ 10 km s-1) high quality (S/N ? 15) spectra of the six UV-brightest starbursts. These starbursts span ranges of 20 in metallicity (1/8 to 2.5 solar) and ˜ 102 in luminosity. The spectra will be used to study: 1) the coronal-phase gas that may dominate the energetics of starburst-driven `superwinds' 2) the H_2 that probably dominates the ISM mass and regulates the star-formation 3) the starburst dust-attenuation law in the unexplored FUV window 4) the stellar content of the starburst (thereby probing the IMF and burst history). These will be the finest UV spectra obtained to-date for starbursts. In particular, the FUSE MDRS aperture allows us to obtain high-resolution spectra of nearly the entire starburst (rather than small pieces, as with HST and STIS).

Heckman, Timothy

220

Shape effects on asteroid spectra  

NASA Astrophysics Data System (ADS)

The objective of this work is to probe how the shape of a body like an asteroid could be modifying its observed spectra and the derived mineralogical interfaces based on spectral modeling. To model this effect, we construct an oblate ellipsoid with triangular facets, where each facet contributes to the overall reflectance. The synthetic spectra is generated by the isotropic multiple-scattering approximation (IMSA) reflectance model of Hapke (1993). First, we obtained optical constants by inverting the spectra of meteorites, obtained from the RELAB spectral database. These optical constants were found inverting the reflectance bidirectional equation of Hapke; this is made in two steps: (i) The first inversion is to find the single-scattering albedo ? (ii) in the model of Hapke, this albedo is found under the regime of the geometric optics, where the particle size is much larger than the wavelength of the incident radiation. Here we assumed a constant value for the real part of the optical constant n=1.5. With these optical constants, we can construct synthetic spectra for any particle size. The phase function used is the double Henyey-Greenstein phase function and an accurate expression for the H-functions. We started with the ellipsoidal shape a=1.0, b=c=0.5 for two particle size 50 and 250 ? m, in this part, we found good differences in the BAR parameter between the two geometric models, this was done for 100 Eucrite meteorites spectra. In this first study, we found that the BAR parameter between the two models is bigger when the particle size increases. In the second part, we started with different ellipsoidal shapes and produced synthetic spectra for material with eucrite and diogenite composition with a phase angle of 20 degrees, incidence and emission angles of 10 degrees, and particle size at 250 ? m. All spectra was generated for four parameters of phase angle b=[0.2,0.4,0.6,0.8] taking the empirical relation between the phase constants of Hapke (2012), where, for the ellipsoidal model, we set the rotational phase at 0 degrees. We observed significant differences between the two models for the band-I area and the band-II area but, we did not find significant differences for the BAR parameter. For the spectral slope, we have meaningful differences between the two models, where the variation of the spectral slope is in the first decimal place, and this difference is bigger when we increase the phase parameter b.

Davalos, J.; Carvano, J.

2014-07-01

221

Source spectra of seismic hum  

NASA Astrophysics Data System (ADS)

The observation of seismic hum from 2 to 20 mHz, also known as Earth's background free oscillations, has been established. Recent observations by broad-band seismometers show simultaneous excitation of Love waves (fundamental toroidal modes) and Rayleigh waves (fundamental spheroidal modes). The excitation amplitudes above 10 mHz can be explained by random shear traction sources on Earth's surface. With estimated source distributions, the most likely excitation mechanism is a linear coupling between ocean infragravity waves and seismic surface waves through seafloor topography. Observed Love and Rayleigh wave amplitudes below 5 mHz suggest that surface pressure sources could also contribute to their excitations, although the amplitudes have large uncertainties due to the high noise levels of the horizontal components. To quantify the observation, we develop a new method for estimation of the source spectra of random tractions on Earth's surface by modelling cross-spectra between pairs of stations. The method is to calculate synthetic cross-spectra for spatially isotropic and homogeneous excitations by random shear traction and pressure sources, and invert them with the observed cross-spectra to obtain the source spectra. We applied this method to the IRIS, ORFEUS, and F-net records from 618 stations with three components of broad-band seismometers for 2004-2011. The results show the dominance of shear traction above 5 mHz, which is consistent with past studies. Below 5 mHz, however, the spectral amplitudes of the pressure sources are comparable to those of shear traction. Observed acoustic resonance between the atmosphere and the solid Earth at 3.7 and 4.4 mHz suggests that atmospheric disturbances are responsible for the surface pressure sources, although non-linear ocean wave processes are also candidates for the pressure sources. Excitation mechanisms of seismic hum should be considered as a superposition of the processes of the solid Earth, atmosphere and ocean as a coupled system.

Nishida, Kiwamu

2014-10-01

222

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

PubMed

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

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

2014-01-01

223

Spectroscopic Properties of Star-Forming Host Galaxies and Type Ia Supernova Hubble Residuals in a Nearly Unbiased Sample  

SciTech Connect

We examine the correlation between supernova host galaxy properties and their residuals on the Hubble diagram. We use supernovae 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 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_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 from host galaxies with active star formation. From a final sample of ~ 40 emission-line galaxies, we find that light-curve corrected Type Ia supernovae are ~ 0.1 magnitudes brighter in high-metallicity hosts than in low-metallicity hosts. We also find a significant (> 3{\\sigma}) correlation between the Hubble residuals of Type Ia supernovae and the specific star-formation rate of the host galaxy. We comment on the importance of supernova/host-galaxy correlations as a source of systematic bias in future deep supernova surveys.

D'Andrea, Chris B.; et al.

2011-12-20

224

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

SciTech Connect

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

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

2011-12-20

225

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

SciTech Connect

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

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

2012-02-10

226

Optimal classification of HCI spectra  

E-print Network

Energy levels of highly charged ions as a rule cannot be classified using LS coupling due to rapid increase of relativistic effects. It is suggested, for optimal classification of energy spectra, to calculate them in LS coupling and to transform the weights of the wave functions, obtained after diagonalization of the energy matrix, to the other coupling schemes. F-like ions are considered as an example.

Gaigalas, G; Rudzikas, Z

1999-01-01

227

Mutational spectra of human cancer  

PubMed Central

The purpose of this review is to summarize the evidence that can be used to reconstruct the etiology of human cancers from mutations found in tumors. Mutational spectra of the tumor suppressor gene p53 (TP53) are tumor-specific. In several cases, these mutational spectra can be linked to exogenous carcinogens, most notably for sunlight-associated skin cancers, tobacco-associated lung cancers, and aristolochic acid-related urothelial tumors. In the TP53 gene, methylated CpG dinucleotides are sequences selectively targeted by endogenous and exogenous mutagenic processes. Recent high-throughput sequencing efforts analyzing a large number of genes in cancer genomes have so far, for the most part, produced mutational spectra similar to those in TP53 but have unveiled a previously unrecognized common G to C transversion mutation signature at GpA dinucleotides in breast cancers and several other cancers. Unraveling the origin of these G to C mutations will be of importance for understanding cancer etiology. PMID:19308457

Pfeifer, Gerd P.; Besaratinia, Ahmad

2010-01-01

228

Optical Spectra and Electronic Structure  

NASA Astrophysics Data System (ADS)

Much of our knowledge of the electronic properties of actinides in solutions and solids is obtained from optical spectroscopy. One of the features that sets actinide spectra apart from those of other elements in the periodic table, aside from the lanthanide series, is that their f-orbitals can be considered both as containing optically active electrons and as belonging to the core of inner shells. As a result of this dominant characteristic, the spectra of these elements, particularly of the lower valence states, are moderately insensitive to changes in the ionic environment. Although ion-ligand interactions shift and split the energy levels of the f-orbitals, the scale of this crystal-field splitting is generally smaller than the intra-ionic Coulomb interaction and spin-orbit coupling. The relative insensitivity of these f-electrons to external forces also means that for these elements there is a close connection between energy levels in compounds and those in gaseous free atoms and ions. Table 18.1 lists the scales of various mechanisms of electronic interactions that will be discussed in this chapter through analysis and modeling of the optical spectra of the various valence states of actinide ions in solutions and compounds.

Liu, Guokui; Beitz, James V.

229

Prediction of earthquake response spectra  

USGS Publications Warehouse

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

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

1982-01-01

230

Spectra/Por Easy-to-Use  

E-print Network

Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 Spectra/Por® Micro Dispo Regenerated Cellulose (RC) seamless membrane attached to a floatable cap for easy handling. No flotation upright and feature our Spectra/Por® Biotech Cellulose Ester (CE) and Regenerated Cellulose (RC) dialysis

Lebendiker, Mario

231

Infrared Spectra of Polycyclic Aromatic Hydrocarbons (PAHs)  

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

232

Infrared spectra of polycyclic aromatic hydrocarbons (PAHs)  

Microsoft Academic Search

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

C. W. Bauschlicher; E. L. O. Bakes

2000-01-01

233

Infrared spectra of polycyclic aromatic hydrocarbons (PAHs)  

NASA Astrophysics Data System (ADS)

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

Bauschlicher, C. W.; Bakes, E. L. O.

2000-12-01

234

Principal Component Analysis of AGN Spectra  

E-print Network

We discuss spectral principal component analysis (SPCA) and show examples of its application in analyzing AGN spectra in both small and large samples. It can be used to identify peculiar spectra and classify AGN spectra. Its application to correlation studies of AGN spectral properties and spectral measurements for large samples is promising.

Zhaohui Shang; Beverley J. Wills

2004-03-26

235

Action spectra for photosynthetic inhibition  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

236

Turbulent Spectra of Interplanetary Shocks  

NASA Astrophysics Data System (ADS)

We have used a newly developed automated detection algorithm for recognition of interplanetary (IP) shocks which is planned to be implemented on board the future Solar Orbiter mission. We have identified more than 800 IP shocks in the Wind measurements during a prolonged time interval (1995 - 2013) with this algorithm. In order to investigate the magnetic field fluctuations in the IP medium we use the Morlet wavelet transform. The fluxgate magnetometer on-board Wind with a sampling frequency of 10 Hz allows us to analyze both inertial ranges and kinetic scales. We have statistically compared turbulent spectra in upstream and downstream of IP shocks.

Kruparova, Oksana; Krupar, Vratislav; Nemecek, Zdenek; Safrankova, Jana

237

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

PubMed

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

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

2014-02-18

238

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

PubMed Central

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

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

2014-01-01

239

C NMR Spectra (see p S10)  

E-print Network

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

Collum, David B.

240

Vibrational Spectra of Chlorinated Poly  

NASA Astrophysics Data System (ADS)

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

Chough, Sung Hyo

241

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

NASA Technical Reports Server (NTRS)

\\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.

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

242

Unveiling the Intrinsic X-Ray Properties of Broad Absorption Line Quasars with a Relatively Unbiased Sample  

NASA Astrophysics Data System (ADS)

There is growing evidence of a higher intrinsic fraction of broad absorption line quasars (BALQSOs) than that obtained in optical surveys, on which most previous X-ray studies of BALQSOs have focused. Here we present Chandra observations of 18 BALQSOs at z ~ 2, selected from a near-infrared (Two Micron All Sky Survey) sample, where the BALQSO fraction is likely to be close to the intrinsic fraction. We measure photon indices using the stacked spectra of the optically faint (i - Ks >= 2.3 mag) and optically bright (i - Ks < 2.3 mag) samples to be ? ~= 1.5-2.1. We constrain their intrinsic column density by modeling the X-ray fractional hardness ratio, finding a mean column density of 3.5 × 1022 cm-2 assuming neutral absorption. We incorporate Sloan Digital Sky Survey optical measurements (rest frame UV) to study the broadband spectral index between the X-ray and UV bands, and compare this to a large sample of normal quasars. We estimate that the optically faint BALQSOs are X-ray weaker than the optically bright ones, and the entire sample of BALQSOs are intrinsically X-ray weak when compared to normal active galactic nuclei (AGNs). Correcting for magnification of X-ray emission via gravitational lensing by the central black hole viewed at large inclination angles makes these BALQSOs even more intrinsically X-ray weak. Finally, we estimate AGN kinetic feedback efficiencies of a few percent for an X-ray wind of 0.3c in high-ionization BALQSOs. Combined with energy carried by low-ionization BALQSOs and UV winds, the total kinetic energy in BALQSOs can be sufficient to provide AGN kinetic feedback required to explain the co-evolution between black holes and host galaxies.

Morabito, Leah K.; Dai, Xinyu; Leighly, Karen M.; Sivakoff, Gregory R.; Shankar, Francesco

2014-05-01

243

Velocity determination from velocity spectra  

E-print Network

' 1300C 14 00 I SUOX 5DQ SOQ ((CP I UI. O HEI/g ng Q T I m E. ITI 5 I'0 I'K )) tQ~P Tl fflE ITS ()l) ) -" SOD (& (U) 0GU 9 5 3 00 ~SP 3500 B ODD Sooof I ODQC flooo 12CD f 3000 1400$ I SRlG Q Figure 15. Ve1ocity spectra...; interval velocity, ft/sec h; thickness, ft d; depth from sea level, ft layer no. 12. 5 20. 5 location (89 no, ) 28. 5 39 43 52 V 1 h d V 2 h d V V 4 h d V 5 h d V 6 h d V 7 h d 6, 400 1, 312 1 &312 8, 549 898 2, 210 11, 311...

Yang, Sung Jin

1973-01-01

244

Graviton Spectra in String Cosmology  

E-print Network

We propose to uncover the signature of a stringy era in the primordial Universe by searching for a prominent peak in the relic graviton spectrum. This feature, which in our specific model terminates an $\\omega^3$ increase and initiates an $\\omega^{-7}$ decrease, is induced during the so far overlooked bounce of the scale factor between the collapsing deflationary era (or pre-Big Bang) and the expanding inflationary era (or post-Big Bang). We evaluate both analytically and numerically the frequency and the intensity of the peak and we show that they may likely fall in the realm of the new generation of interferometric detectors. The existence of a peak is at variance with ordinarily monotonic (either increasing or decreasing) graviton spectra of canonical cosmologies; its detection would therefore offer strong support to string cosmology.

Massimo Galluccio; Marco Litterio; Franco Occhionero

1996-08-02

245

The Theory of Spectra and Atomic Constitution  

NASA Astrophysics Data System (ADS)

Part I. On the Spectrum of Hydrogen: 1. Empirical spectral laws; 2. Laws of temperature radiation; 3. The nuclear theory of the atom; 4. Quantum theory of spectra; 5. Hydrogen spectrum; 6. The Pickering lines; 7. Other spectra; Part II. On the Series Spectra of the Elements; Section 1. Introduction; Section 2. General Principles of the Quantum Theory of Spectra: 8. Hydrogen spectrum; 9. The correspondence principle; 10. General spectral laws; 11. Absorption and excitation of radiation; Section 3. Development of the Quantum Theory of Spectra: 12. Effect of external forces on the hydrogen spectrum; 13. The Stark effect; 14. The Zoeman effect; 15. Central pertubations; 16. Relativity effect of hydrogen lines; 17. Theory of series spectra; 18. Correspondence principle and conservation of angular momentum; 19. The spectra of helium and lithium; 20. Complex structure of series lines; Section 4. Conclusion; Part III. The Structure of the Atom and the Physical and Chemical Properties of the Elements; Section 5. Preliminary: 21. The nuclear atom; 22. The postulates of the quantum theory; 23. Hydrogen atom; 24. Hydrogen spectrum and x-ray spectra; 25. The fine structure of the hydrogen lines; 26. Periodic table; 27. Recent atomic models; Section 6. Series Spectra and the Capture of Electrons by Atoms: 28. Arc and spark spectra; 29. Series diagram; 30. Correspondence principle; Section 7. Formation of Atoms and the Periodic Table: 31. First period. Hydrogen-helium; 32. Second period. Lithium-neon; 33. Third period. Sodium-argon; 34. Fourth period. Potassium-Krypton; 35. Fifth period. Rubidium-xenon; 36. Sixth period. Caesium-niton; 37. Seventh period; 38. Survey of the periodic table; Section 8. Reorganization of Atoms and X-Ray SPectra: 39. Absorption and emission of x-rays and correspondence principle; 40. X-ray spectra and atomic structure; 41. Classification of x-ray spectra; 42. Conclusion; Appendix.

Bohr, Niels

2011-06-01

246

THE SUZAKU VIEW OF THE SWIFT/BAT ACTIVE GALACTIC NUCLEI. II. TIME VARIABILITY AND SPECTRA OF FIVE 'HIDDEN' ACTIVE GALACTIC NUCLEI  

SciTech Connect

The fraction of Compton-thick sources is one of the main uncertainties left in understanding the active galactic nucleus (AGN) population. The Swift Burst Alert Telescope (BAT) all-sky survey for the first time gives us an unbiased sample of AGNs for all but the most heavily absorbed sources N {sub H} > 10{sup 25} cm{sup -2}). Still, the BAT spectra (14-195 keV) are time averaged over months of observations and therefore hard to compare with softer spectra from the Swift XRT or other missions. This makes it difficult to distinguish between Compton-thin and Compton-thick models. With Suzaku, we have obtained simultaneous hard (>15 keV) and soft (0.3-10 keV) X-ray spectra for five Compton-thick candidate sources. We report on the spectra and a comparison with the BAT and earlier XMM observations. Based on both flux variability and spectral shape, we conclude that these hidden sources are not Compton thick. We also report on a possible correlation between excess variance and Swift BAT luminosity from the 16 day binned light curves, which holds true for a sample of both absorbed (four sources), unabsorbed (eight sources), and Compton-thick (Circinus) AGNs, but is weak in the 64 day binned BAT light curves.

Winter, Lisa M. [Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309 (United States); Mushotzky, Richard F. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Terashima, Yuichi [Department of Physics, Ehime University, Matsuyama, Ehime 790-8577 (Japan); Ueda, Yoshihiro [Department of Astronomy, University of Kyoto, Kyoto 606-8502 (Japan)

2009-08-20

247

Photoemission spectra of many-polaron systems  

NASA Astrophysics Data System (ADS)

The crossover from low to high carrier densities in a many-polaron system is studied in the framework of the one-dimensional spinless Holstein model, using unbiased numerical methods. Combining a novel quantum Monte Carlo approach and exact diagonalization, accurate results for the single-particle spectrum and the electronic kinetic energy on fairly large systems are obtained. A detailed investigation of the quality of the Monte Carlo data is presented. In the physically most important adiabatic intermediate electron-phonon coupling regime, for which no analytical results are available, we observe a dissociation of polarons with increasing band filling, leading to normal metallic behavior, while for parameters favoring small polarons, no such density-driven changes occur. The present work points toward the inadequacy of single-polaron theories for a number of polaronic materials such as the manganites.

Hohenadler, M.; Neuber, D.; von der Linden, W.; Wellein, G.; Loos, J.; Fehske, H.

2005-06-01

248

Infrared spectra of natural and synthetic malachites  

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

249

Spectra in the Digitized First Byurakan Survey  

NASA Astrophysics Data System (ADS)

The Digitized First Byurakan Survey (DFBS) is accessible on a dedicated web site at the Department of Physics of La Sapienza University. It covers about 17 000 square degrees and provides low resolution spectra of sources down to B = 16.5 mag. Both the digitized plates and the automatically extracted spectra can be retrieved. We present the main characteristics of the spectra and their relevance as proxies for the low dispersion spectra which will be provided by the forthcoming Gaia mission. Detectability of spectral features, overall spectral energy distribution and accuracy of the photometric information is briefly discussed.

Nesci, R.; Rossi, C.; Cirimele, G.

250

Orlov spectra: bounds and gaps  

NASA Astrophysics Data System (ADS)

The Orlov spectrum is a new invariant of a triangulated category. It was introduced by D. Orlov building on work of A. Bondal-M. van den Bergh and R. Rouquier. The supremum of the Orlov spectrum of a triangulated category is called the ultimate dimension. In this work, we study Orlov spectra of triangulated categories arising in mirror symmetry. We introduce the notion of gaps and outline their geometric significance. We provide the first large class of examples where the ultimate dimension is finite: categories of singularities associated to isolated hypersurface singularities. Similarly, given any nonzero object in the bounded derived category of coherent sheaves on a smooth Calabi-Yau hypersurface, we produce a new generator by closing the object under a certain monodromy action and uniformly bound this new generator's generation time. In addition, we provide new upper bounds on the generation times of exceptional collections and connect generation time to braid group actions to provide a lower bound on the ultimate dimension of the derived Fukaya category of a symplectic surface of genus greater than one.

Ballard, Matthew; Favero, David; Katzarkov, Ludmil

2012-08-01

251

Modelling asteroid spectra: few examples  

NASA Astrophysics Data System (ADS)

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.

Birlan, M.; Popescu, M.

2011-10-01

252

Reflectance spectra of subarctic lichens  

NASA Technical Reports Server (NTRS)

Lichens constitute a major portion of the ground cover of high latitude environments, but little has been reported concerning their in situ solar spectral reflectance properties. Knowledge of these properties is important for the interpretation of remotely sensed observations from high latitude regions, as well as in studies of high latitude ecology and energy balance climatology. The spectral reflectance of common boreal vascular plants is similar to that of vascular plants of the midlatitudes. The dominant lichens, in contrast, display variable reflectance patterns in visible wavelengths. The relative reflectance peak at 0.55 microns, common to green vegetation, is absent or indistinct in spectra of pervasive boreal forest and tundra lichens, despite the presence of chlorophyll in the inner algal cells. Lichens of the dominant genus, Cladina, display strong absorption of ultraviolet energy and short-wavelength blue light relative to their absorption in other visible wavelengths. Since the Cladinae dominate both the surface vegetation in open woodlands of the boreal forest and the low arctic tundra, their unusual spectral reflectance patterns will enable accurate monitoring of the boreal forest-tundra ecotone and detection of its vigor and movement in the future.

Petzold, Donald E.; Goward, Samuel N.

1988-01-01

253

Mass Spectra Alignments and their Significance  

E-print Network

¨ocker, Kaltenbach Mass Spectra Alignments CPM 2005 #12;Overview Mass Spectrometry in Proteomics Protein Alignments CPM 2005 #12;Overview Mass Spectrometry in Proteomics Protein Identification via MS Alignment Mass Spectrometry in Proteomics Protein Identification via MS Alignment of Spectra Score Significance

Lonardi, Stefano

254

DYNAMIC SPECTRA OF JUPITER'S DECAMETRIC EMISSION, 1961  

Microsoft Academic Search

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

James W. Warwick

1963-01-01

255

Extreme-Ultraviolet Spectra of Ionic Crystals  

Microsoft Academic Search

The absorption spectra of several ionic crystals were obtained by the use of synchrotron radiation with photon energies in the range 50-250 eV. This range includes thresholds for excitation of both p and d core states. Arguments are given that peaks in the observed spectra are generally due to maxima in the final density of states, rather than exciton phenomena.

Frederick C. Brown; Christian Gähwiller; Hiizu Fujita; A. Barry Kunz; William Scheifley; Nicholas Carrera

1970-01-01

256

Predictions of LET spectra measured on LDEF  

NASA Technical Reports Server (NTRS)

The linear energy transfer (LET) spectra measured by plastic (CR-39) detectors in Exp. P0006 on LDEF are much higher at high LET than expected from methods commonly used to predict LET spectra produced by the space ionizing radiation environment. This discrepancy is being investigated by examining modeling approximations used in the predictions, and some interim results are presented.

Armstrong, T. W.; Colborn, B. L.; Benton, E. V.

1995-01-01

257

Early time spectra of type IA supernovae  

Microsoft Academic Search

Theoretical models for SN Ia and their ability to explain the early spectral evolution of type Ia SNs are discussed. Spectra of SN Ia 1981B in NGC 4536 are presented and their maximum light spectra during early evolution are discussed. It is suggested that the most successful theoretical model for SN Ia involves the thermonuclear incineration of a carbon\\/oxygen white

Robert Harkness

1987-01-01

258

Resolution enhancement in second-derivative spectra.  

PubMed

Derivative spectroscopy is a powerful tool for the resolution enhancement in infrared, near-infrared, Raman, ultraviolet-visible, nuclear magnetic resonance, electron paramagnetic resonance, and fluorescence spectroscopy. Despite its great significance in analytical chemistry, not all aspects of the applications of this method have been explored as yet. This is the first systematic study of the parameters that influence the resolution enhancement in the second derivative spectra. The derivative spectra were calculated with the Savitzky-Golay method with different window size (5, 15, 25) and polynomial order (2, 4). The results obtained in this work show that the resolution enhancement in the second derivative spectra strongly depends on the data spacing in the original spectra, window size, polynomial order, and peak profile. As shown, the resolution enhancement is related to variations in the width of the peaks upon the differentiation. The present study reveals that in order to maximize the separation of the peaks in the second derivative spectra, the original spectra should be recorded at high resolution and differentiated using a small window size and high polynomial order. However, working with the real spectra one has to compromise between the noise reduction and optimization of the resolution enhancement in the second derivative spectra. PMID:25499557

Czarnecki, Miros?aw A

2015-01-01

259

Spectra of Quarkonia at Finite Temperature  

E-print Network

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

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

2006-06-02

260

Autoionic mass spectra of organic substances. Amines  

Microsoft Academic Search

The mass spectra of primary (methylamine, ethylamine, aniline, and benzylamine), secondary (dimethylamine and diethylamine), and tertiary (trimethylamtne and triethylamine) amines and also tertiary amines of the type (CH~2NCH2-R have been investigated in the present work. Fundamental attention has been paid to the study of the composition of the mass spectra at various values of the voltage of the ionizing field.

I. Z. Korostyshevskii; I. V. Gol'denfel'd; M. M. Aleksankin; I. P. Vatlina; L. I. Fileleeva

1974-01-01

261

Frequency spectra of absolute optical instruments  

NASA Astrophysics Data System (ADS)

We analyze frequency spectra of optical devices called absolute optical instruments. We show that they have very specific properties: the eigenfrequencies form tight, almost equidistantly spaced groups. We prove this by theoretical analysis and demonstrate by numerically calculated spectra of various examples of absolute instruments.

Tyc, Tomáš; Danner, Aaron

2012-09-01

262

Microwave Spectra of Fluoroformyloxyl and Fluorosulfate Radicals  

Microsoft Academic Search

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

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

2010-01-01

263

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...

264

The Usage of an SNP-SNP Relationship Matrix for Best Linear Unbiased Prediction (BLUP) Analysis Using a Community-Based Cohort Study  

PubMed Central

Best linear unbiased prediction (BLUP) has been used to estimate the fixed effects and random effects of complex traits. Traditionally, genomic relationship matrix-based (GRM) and random marker-based BLUP analyses are prevalent to estimate the genetic values of complex traits. We used three methods: GRM-based prediction (G-BLUP), random marker-based prediction using an identity matrix (so-called single-nucleotide polymorphism [SNP]-BLUP), and SNP-SNP variance-covariance matrix (so-called SNP-GBLUP). We used 35,675 SNPs and R package "rrBLUP" for the BLUP analysis. The SNP-SNP relationship matrix was calculated using the GRM and Sherman-Morrison-Woodbury lemma. The SNP-GBLUP result was very similar to G-BLUP in the prediction of genetic values. However, there were many discrepancies between SNP-BLUP and the other two BLUPs. SNP-GBLUP has the merit to be able to predict genetic values through SNP effects. PMID:25705167

Lee, Young-Sup; Kim, Hyeon-Jeong; Cho, Seoae

2014-01-01

265

PCA: Principal Component Analysis for spectra modeling  

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

266

Mid-Infrared Spectra of Mercury  

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

267

Characteristics of energetic solar flare electron spectra  

NASA Technical Reports Server (NTRS)

A 55 event survey of energy spectra of 0.1-100 MeV interplanetary electrons originating from solar flares as measured by two spectrometers onboard the ISEE 3 (ICE) spacecraft for the years 1978-1982 has been completed. Spectra generated using the maximum flux of a given event in each energy channel were restricted to events with a well-defined flux rise time. Two broad groups of electron spectra are considered. In one group, the spectra are well represented by a single power law in rigidity with spectral index in the range 3-4.5. The spectra in the other group deviate from a power law in rigidity systematically in that they harden with increasing rigidity. Events with near power-law spectra are found to be correlated with long-duration soft X-ray events, whereas those with hardening spectra are correlated with short-duration events. The possible variation of acceleration and propagation processes with the properties of the flare site is discussed, using the duration of the soft X-ray flare emission as an indicator of the physical parameters of the flare site (flare volume, density, coronal height, and magnetic field geometry).

Moses, Dan; Droege, Wolfgang; Meyer, Peter; Evenson, Paul

1989-01-01

268

Spectra of magnetic fields injected during baryogenesis  

SciTech Connect

Helical magnetic fields are injected into the cosmic medium during cosmological baryogenesis and can potentially provide a useful probe of the early universe. We construct a model to study the injection process during a first order phase transition and to determine the power spectra of the injected magnetic field. By Monte Carlo simulations we evaluate the Fourier space symmetric and helical power spectra of the magnetic field at the time the phase transition completes. The spectra are peaked at the scale given by the inverse size of bubbles at percolation and with a comparable width. These injected magnetic fields set the initial conditions for further cosmological magneto-hydrodynamical evolution.

Ng Yifung [CERCA, Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106-7079 (United States); Vachaspati, Tanmay [CERCA, Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106-7079 (United States); Institute for Advanced Study, Princeton, New Jersey 08540 (United States)

2010-07-15

269

IRAS low-resolution spectra of galaxies  

NASA Technical Reports Server (NTRS)

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

Cohen, Martin; Volk, Kevin

1989-01-01

270

Simulation of x-ray fluorescence spectra  

SciTech Connect

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

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

1996-09-01

271

Analysis of atmospheric spectra for trace gases  

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

272

Anisotropic spectra of acoustic type turbulence  

SciTech Connect

The problem of spectra for acoustic type of turbulence generated by shocks being randomly distributed in space is considered. It is shown that for turbulence with a weak anisotropy, such spectra have the same dependence in k-space as the Kadomtsev-Petviashvili spectrum: E(k){approx}k{sup -2}. However, the frequency spectrum has always the falling {approx}{omega}{sup -2}, independent of anisotropy. In the strong anisotropic case the energy distribution relative to wave vectors takes anisotropic dependence, forming in the large-k region spectra of the jet type.

Kuznetsov, E. [LPCE, 3A Avenue de la Recherche Scientifique 45071 Orleans, CEDEX 2 (France); P.N. Lebedev Physical Institute, 53 Leninsky Ave., 119991 Moscow (Russian Federation); Krasnoselskikh, V. [LPCE, 3A Avenue de la Recherche Scientifique 45071 Orleans, CEDEX 2 (France)

2008-06-15

273

Higher-Order Septin Assembly Is Driven by GTP-Promoted Conformational Changes: Evidence From Unbiased Mutational Analysis in Saccharomyces cerevisiae  

PubMed Central

Septin proteins bind GTP and heterooligomerize into filaments with conserved functions across a wide range of eukaryotes. Most septins hydrolyze GTP, altering the oligomerization interfaces; yet mutations designed to abolish nucleotide binding or hydrolysis by yeast septins perturb function only at high temperatures. Here, we apply an unbiased mutational approach to this problem. Mutations causing defects at high temperature mapped exclusively to the oligomerization interface encompassing the GTP-binding pocket, or to the pocket itself. Strikingly, cold-sensitive defects arise when certain of these same mutations are coexpressed with a wild-type allele, suggestive of a novel mode of dominance involving incompatibility between mutant and wild-type molecules at the septin–septin interfaces that mediate filament polymerization. A different cold-sensitive mutant harbors a substitution in an unstudied but highly conserved region of the septin Cdc12. A homologous domain in the small GTPase Ran allosterically regulates GTP-binding domain conformations, pointing to a possible new functional domain in some septins. Finally, we identify a mutation in septin Cdc3 that restores the high-temperature assembly competence of a mutant allele of septin Cdc10, likely by adopting a conformation more compatible with nucleotide-free Cdc10. Taken together, our findings demonstrate that GTP binding and hydrolysis promote, but are not required for, one-time events—presumably oligomerization-associated conformational changes—during assembly of the building blocks of septin filaments. Restrictive temperatures impose conformational constraints on mutant septin proteins, preventing new assembly and in certain cases destabilizing existing assemblies. These insights from yeast relate directly to disease-causing mutations in human septins. PMID:24398420

Weems, Andrew D.; Johnson, Courtney R.; Argueso, Juan Lucas; McMurray, Michael A.

2014-01-01

274

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

PubMed Central

The Latency-Associated Nuclear Antigen (LANA), encoded by ORF73, is a conserved gene among the ?2-herpesviruses (rhadinoviruses). The Kaposi's Sarcoma-Associated Herpesvirus (KSHV) LANA is consistently expressed in KSHV-associated malignancies. In the case of the rodent ?2-herpesvirus, murine gammaherpesvirus 68 (MHV68), the LANA homolog (mLANA) is required for efficient virus replication, reactivation from latency and immortalization of murine fetal liver-derived B cells. To gain insights into mLANA function(s), knowing that KSHV LANA binds DNA and can modulate transcription of a variety of promoters, we sought out and identified a mLANA-responsive promoter which maps to the terminal repeat (TR) of MHV68. Notably, mLANA strongly repressed activity from this promoter. We extended these analyses to demonstrate direct, sequence-specific binding of recombinant mLANA to TR DNA by DNase I footprinting. To assess whether the DNA-binding and/or transcription modulating function is important in the known mLANA phenotypes, we generated an unbiased library of mLANA point mutants using error-prone PCR, and screened a large panel of mutants for repression of the mLANA-responsive promoter to identify loss of function mutants. Notably, among the mutant mLANA proteins recovered, many of the mutations are in a predicted EBNA-1-like DNA-binding domain. Consistent with this prediction, those tested displayed loss of DNA binding activity. We engineered six of these mLANA mutants into the MHV68 genome and tested the resulting mutant viruses for: (i) replication fitness; (ii) efficiency of latency establishment; and (iii) reactivation from latency. Interestingly, each of these mLANA-mutant viruses exhibited phenotypes similar to the mLANA-null mutant virus, indicating that DNA-binding is critical for mLANA function. PMID:22969427

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

2012-01-01

275

An unbiased stereological study on subpopulations of rat liver macrophages and on their numerical relation with the hepatocytes and stellate cells  

PubMed Central

Studies on liver macrophages have elucidated their key roles in immunological, fibrotic and regenerative responses, and shown that macrophages are not a homogeneous population. In the rat, two sets of liver macrophages coexist, identified by ED1 and ED2 antibodies. Those sets have different quantitative responses in liver injuries and may have different tasks throughout the injury and recovery phases. Nevertheless, the total number (N), number per gram (N g?1) and proportion of those macrophages in relation to other liver cells has never been quantified using design-based stereology. Thus, we combined immunocytochemistry with those tools to produce an unbiased estimate of the N of ED1+ and of ED2+ cells. A smooth fractionator sampling scheme was applied to the liver of five male Wistar rats (3 months old), to obtain systematic uniform random sections (30 µm thick); these were immunostained with the monoclonal antibodies: ED1, a pan-macrophagic marker; and ED2, which identifies the completely differentiated macrophages, i.e. Kupffer cells. The N of ED1+ cells was 340 × 106, estimated with a coefficient of error (CE) of 0.04, and that of ED2+ cells was 283 × 106, with a CE of 0.05. These figures correspond to 10.7% and 8.9%, respectively, of the total liver cells. The new data constitute reference values for correlative inferences. Also, the methodological strategy, by its accuracy and precision, is valuable for future investigations on the liver cell composition in various models of disease, and especially for studying the more subtle variations that occur during the injury and recovery phases. PMID:19438768

Santos, Marta; Marcos, Ricardo; Santos, Nádia; Malhão, Fernanda; Monteiro, Rogério A F; Rocha, Eduardo

2009-01-01

276

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

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

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

2014-03-01

277

Connecting GRBs and ULIRGs: A Sensitive, Unbiased Survey for Radio Emission from Gamma-Ray Burst Host Galaxies at 0 < z < 2.5  

NASA Astrophysics Data System (ADS)

Luminous infrared galaxies and submillimeter galaxies contribute significantly to stellar mass assembly and provide an important test of the connection between the gamma-ray burst (GRB) rate and that of overall cosmic star formation. We present sensitive 3 GHz radio observations using the Karl G. Jansky Very Large Array of 32 uniformly selected GRB host galaxies spanning a redshift range from 0 < z < 2.5, providing the first fully dust- and sample-unbiased measurement of the fraction of GRBs originating from the universe's most bolometrically luminous galaxies. Four galaxies are detected, with inferred radio star formation rates (SFRs) ranging between 50 and 300 M ? yr–1. Three of the four detections correspond to events consistent with being optically obscured "dark" bursts. Our overall detection fraction implies that between 9% and 23% of GRBs between 0.5 < z < 2.5 occur in galaxies with S 3GHz > 10 ?Jy, corresponding to SFR > 50 M ? yr–1 at z ~ 1 or >250 M ? yr–1 at z ~ 2. Similar galaxies contribute approximately 10%-30% of all cosmic star formation, so our results are consistent with a GRB rate that is not strongly biased with respect to the total SFR of a galaxy. However, all four radio-detected hosts have stellar masses significantly lower than IR/submillimeter-selected field galaxies of similar luminosities. We suggest that the GRB rate may be suppressed in metal-rich environments but independently enhanced in intense starbursts, producing a strong efficiency dependence on mass but little net dependence on bulk galaxy SFR.

Perley, D. A.; Perley, R. A.; Hjorth, J.; Micha?owski, M. J.; Cenko, S. B.; Jakobsson, P.; Krühler, T.; Levan, A. J.; Malesani, D.; Tanvir, N. R.

2015-03-01

278

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

NASA Astrophysics Data System (ADS)

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

Kaneko, Y.; Shearer, P. M.

2014-05-01

279

Synthesis and Spectra of Vanadium Complexes.  

ERIC Educational Resources Information Center

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

Ophardt, Charles E.; Stupgia, Sean

1984-01-01

280

Comparing Ultraviolet Spectra Against Calculations: First Results  

NASA Technical Reports Server (NTRS)

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

Peterson, Ruth C.

2003-01-01

281

Microwave spectra of some volatile organic compounds  

NASA Technical Reports Server (NTRS)

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

White, W. F.

1975-01-01

282

Second derivative infrared spectra of hydroxyapatite  

NASA Astrophysics Data System (ADS)

Infrared absorption spectra of polycrystalline fluor- and hydroxyapatite are transformed to their second derivatives for resolution enhancement. It is observed that although the symmetry of the hydroxyapatite lattice is lower than that of fluorapatite, the spectra are nearly congruent. The data of polycrystalline samples are analysed on the basis of single crystal Raman and infrared dichroism spectra. The number of vibrational bands that are observed in the spectra of polycrystalline fluor- and hydroxyapatite exceed the number predicted by factor group analysis. The "excess" bands are assigned to vibrations that are expected to be Raman active previously reported in the single crystal Raman data of these two minerals. This can be accounted for by a breakdown of factor group selection rules as applied to the infrared data of polycrystalline apatites.

Leung, Yiuchong; Walters, M. Anton; LeGeros, Racquel Z.

283

The SPECTRa Project: A Wider Chemistry View  

E-print Network

synthetic organic chemistry departmental crystallography services computational chemistry determined by interview and survey The Problem Science depends upon data Experimental chemistry data is a resource / asset … Proprietary spectra formats (NMR, IR...

Downing, Jim; Tonge, Alan

2006-10-20

284

Contribution to the study of turbulence spectra  

NASA Technical Reports Server (NTRS)

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.

Dumas, R.

1979-01-01

285

The Polarizabilities of Ions from Spectra  

Microsoft Academic Search

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 \\

Joseph E. Mayer; Maria Goeppert Mayer

1933-01-01

286

Angular power spectra with finite counts  

NASA Astrophysics Data System (ADS)

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.

Campbell, Sheldon S.

2015-04-01

287

Area spectra of near extremal black holes  

E-print Network

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

Deyou Chen; Haitang Yang; Xiaotao Zu

2010-04-20

288

Universality of spectra of black holes  

NASA Astrophysics Data System (ADS)

Using exclusively an action variable, we quantize a static, spherically symmetric black hole. The spacings of the quantized entropy spectrum and area spectrum are found to be equal to the values given by Bekenstein. Interestingly, we find the spectra are independent of the hairs of the black holes and the mode of motion of a particle outside the spacetime, which depends only on the intrinsic properties of the gravity. Our result shows that the spectra are universal provided the spacetime owns a horizon.

Zeng, Xiao-Xiong; Li, Qiang; Han, Yi-Wen

2014-11-01

289

Silicon Kedge XANES spectra of silicate minerals  

Microsoft Academic Search

Silicon K-edge x-ray absorption near-edge structure (XANES) spectra of a selection of silicate and aluminosilicate minerals have been measured using synchrotron radiation (SR). The spectra are qualitatively interpreted based on MO calculation of the tetrahedral SiO44-cluster. The Si K-edge generally shifts to higher energy with increased polymerization of silicates by about 1.3 eV, but with considerable overlap for silicates of

Dien Li; G. M. Bancroft; M. E. Fleet; X. H. Feng

1995-01-01

290

Power spectra of the interplanetary magnetic field  

Microsoft Academic Search

Power spectra based on Pioneer 6 interplanetary magnetic field data in early 1966 exhibit a frequency dependence of f-2 in the range 2.8 × 10-4 to 1.6 × 10-2 cps for periods of both quiet and disturbed field conditions. Both the shape and power levels of these spectra are found to be due to the presence of directional discontinuities in

James W. Sari; Norman F. Ness

1969-01-01

291

Characteristics of energetic solar flare electron spectra  

Microsoft Academic Search

A 55 event survey of energy spectra of 0.1-100 MeV interplanetary electrons originating from solar flares as measured by two spectrometers onboard the ISEE 3 (ICE) spacecraft for the years 1978-1982 has been completed. Spectra generated using the maximum flux of a given event in each energy channel were restricted to events with a well-defined flux rise time. Two broad

Dan Moses; Wolfgang Droege; Peter Meyer; Paul Evenson

1989-01-01

292

Power and phase spectra for detonating cord  

SciTech Connect

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

Burkhard, N.R.

1983-11-01

293

Frequency spectra of absolute optical instruments  

NASA Astrophysics Data System (ADS)

We analyse frequency spectra of absolute optical instruments and show that they have very specific properties: the eigenfrequencies form tight groups that are almost equidistantly spaced. We prove this by theoretical analysis and demonstrate by numerically calculated spectra of various examples of absolute instruments. We also show that in rotationally and spherically symmetric absolute instruments a source, its image and the centre of the device must lie on a straight line.

Tyc, Tomáš; Danner, Aaron

2012-08-01

294

Diffuse emission and pathological Seyfert spectra  

NASA Technical Reports Server (NTRS)

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.

Halpern, Jules P.

1995-01-01

295

Good abundances from bad spectra - I. Techniques  

NASA Astrophysics Data System (ADS)

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

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

1996-01-01

296

Fingerprints of correlation in electronic spectra Lucia Reining  

E-print Network

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

Botti, Silvana

297

Infrared spectra of urine from cancerous bladders  

NASA Astrophysics Data System (ADS)

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

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

1996-06-01

298

Background noise spectra of global seismic stations  

SciTech Connect

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

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

1996-08-01

299

Disk-averaged synthetic spectra of Mars.  

PubMed

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

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

2005-08-01

300

Disk-averaged synthetic spectra of Mars  

NASA Technical Reports Server (NTRS)

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.

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

2005-01-01

301

EXPLORING THE MORPHOLOGY OF RAVE STELLAR SPECTRA  

SciTech Connect

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

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

2012-06-01

302

Spectra from nuclear-excited plasmas  

NASA Technical Reports Server (NTRS)

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

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

1980-01-01

303

Good Abundances from Bad Spectra: I. Techniques  

E-print Network

We have developed techniques to extract true iron abundances and surface gravities from spectra of the type provided by the multiple-object fibre-fed spectroscopic radial-velocity surveys underway with 2dF, HYDRA, NESSIE, and the forthcoming Sloan survey. Our method is optimised for low S/N, intermediate resolution blue spectra of G stars. Spectroscopic indices sensitive to iron abundance and gravity are defined from a set of narrow (few Angstrom) wavelength intervals, and calibrated using synthetic spectra. We have also defined a single abundance indicator which is able to provide useful iron abundance information from spectra having S/N ratios as low as 10 per Angstrom. The theoretical basis and calibration using synthetic spectra are described in this paper. The empirical calibration of these techniques by application to observational data is described in Jones, Wyse and Gilmore (PASP July 1995). The technique provides precise iron abundances, with zero-point correct to $\\sim 0.1$ dex, and is reliable, with typical uncertainties being $\\approxle 0.2$ dex. A derivation of the {\\it in situ\\/} thick disk metallicity distribution using these techniques is presented by Gilmore, Wyse and Jones (AJ 1995 v109 p1095).

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

1995-07-24

304

Exploring the Morphology of RAVE Stellar Spectra  

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

305

Host Galaxy Spectra and Consequences for Supernova Typing from the SDSS SN Survey  

NASA Astrophysics Data System (ADS)

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.

Olmstead, Matthew D.; Brown, Peter J.; Sako, Masao; Bassett, Bruce; Bizyaev, Dmitry; Brinkmann, J.; Brownstein, Joel R.; Brewington, Howard; Campbell, Heather; D'Andrea, Chris B.; Dawson, Kyle S.; Ebelke, Garrett L.; Frieman, Joshua A.; Galbany, Lluís; Garnavich, Peter; Gupta, Ravi R.; Hlozek, Renee; Jha, Saurabh W.; Kunz, Martin; Lampeitl, Hubert; Malanushenko, Elena; Malanushenko, Viktor; Marriner, John; Miquel, Ramon; Montero-Dorta, Antonio D.; Nichol, Robert C.; Oravetz, Daniel J.; Pan, Kaike; Schneider, Donald P.; Simmons, Audrey E.; Smith, Mathew; Snedden, Stephanie A.

2014-04-01

306

Optical High Resolution Spectra of APOGEE Stars  

NASA Astrophysics Data System (ADS)

The Apache Point Observatory Galactic Evolution Experiment (APOGEE) is an SDSS-III survey that is obtaining high resolution near-IR (H band) spectra of 100,000 Milky Way stars in an effort to chemically trace formation and evolution of Galactic stellar populations. Optical echelle spectra of a small subset of survey targets have been obtained with the ARC 3.5m telescope for the purpose of 1) helping to understand and calibrate the abundance analysis of the APOGEE IR spectra, and 2) measuring abundances of elements that do not have spectral features in the APOGEE wavelength region, which will ideally include neutron capture elements. We present our current sample of ~130 (out of a projected 500) stars, which is drawn from the brightest APOGEE targets and covers a range of stellar parameters (temperature, metallicity, and surface gravity), and compare some optically derived quantities with those from the APOGEE abundance pipeline.

Feuillet, Diane; Holtzman, J. A.; Cunha, K. M.; Garcia Perez, A.; Ghezzi, L.; Hayden, M. R.; Meszaros, Sz.; Allende Prieto, C.; Shetrone, M. D.; Smith, V. V.; Zasowski, G.

2013-01-01

307

Mid-Infrared Spectra of Be Stars  

E-print Network

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.

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

1999-10-11

308

BRUCE/KYLIE: Pulsating star spectra synthesizer  

NASA Astrophysics Data System (ADS)

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

Townsend, Rich

2014-12-01

309

Structures in the cosmic ray energy spectra  

E-print Network

All the components of cosmic rays have 'structure' in their energy spectra at some level, ie deviations from a simple power law, and their examination is relevant to the origin of the particles. Emphasis, here, is placed on the large-scale structures in the spectra of nuclei (the 'knee' at about 3 PeV), that of electrons and positrons (a shallow 'upturn' at about 100 GeV) and the positron to electron plus positron ratio (an upturn starting at about 5 GeV). Fine structure is defined as deviations from the smooth spectra which already allow for the large-scale structure. Search for the fine structure has been performed in the precise data on positron to electron plus positron ratio measured by the AMS-02 experiment. Although no fine structure is indicated, it could in fact be present at the few percent level.

Erlykin, Anatoly

2013-01-01

310

Vibrational spectra of molecular fluids in nanopores  

NASA Astrophysics Data System (ADS)

Coherent anti-Stokes Raman spectroscopy (CARS) is applied for quantitative analysis of carbon dioxide phase composition in pores of nanoporous glass samples at nearcritical temperatures. Measurements of the 1388 1/cm Q-branch were made in a wide pressure range corresponding to coexistence of gas (gas-like), adsorbed and condensed phases within pores. At temperatures several degrees below the critical value, CARS spectra behavior is easy to interpret in terms of thermodynamic model of surface adsorption and capillary condensation. It allows estimating mass fractions of different phase components. Moreover, spectra measured at near critical temperatures 30.5 and 33°C have pronounced inhomogeneous shapes and indicate the presence of condensed phase in the volume of pores. The effect obviously reflects the fluid behaviour near the critical point in nanopores. Pores with smaller radii are filled with condensed phase at lower pressures. The analysis of the CARS spectra is informative for quantitative evaluation of phase composition in nanopores.

Arakcheev, V. G.; Morozov, V. B.

2012-12-01

311

Fast Inversion of Solar Ca II Spectra  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

312

Consistency of the minimal supersymmetric GUT spectra  

SciTech Connect

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

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

2005-09-01

313

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

Microsoft Academic Search

An earlier algorithm for retrieving two-dimensional wave spectra from synthetic aperture radar (SAR) image spectra is improved by using a modified cost function and introducing an additional iteration loop in which the first-guess input spectrum is systematically updated. For this purpose a spectral partitioning scheme is applied in which the spectrum is decomposed into a finite number of distinct wave

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

1996-01-01

314

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

SciTech Connect

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

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

1991-11-01

315

AIS-2 spectra of California wetland vegetation  

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

316

Parallel Genetic Algorithm for Alpha Spectra Fitting  

NASA Astrophysics Data System (ADS)

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

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

2005-01-01

317

What can we learn from inclusive spectra  

SciTech Connect

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

Nagamiya, S.

1981-05-01

318

Photoabsorption spectra of cationic mercury clusters  

SciTech Connect

The experimental photoabsorption spectra of singly charged cationic mercury clusters (Hg{sub N}{sup +}) show a sharp change in behavior at cluster size N=6. Both relativistic density functional theory (DFT) and wave function based methods reveal that this corresponds to a structural change from linear to three-dimensional isomers. The simulated electronic excitation spectra obtained from time-dependent relativistic DFT agree well with the experimental results. Our quantum theoretical treatment confirms the change from single electron-hole excitations in small linear clusters to plasmonlike collective transitions for the larger three-dimensional clusters.

Gaston, Nicola; Schwerdtfeger, Peter; Issendorff, Bernd von [Centre of Theoretical Chemistry and Physics, Institute of Fundamental Sciences, Massey University (Auckland Campus), Private Bag 102904, North Shore MSC, Auckland (New Zealand); Fakultaet fuer Physik, Universitaet Freiburg, H. Herderstrasse 3, D-79104 Freiburg (Germany)

2006-10-15

319

Near IR spectra of symbiotic stars  

NASA Astrophysics Data System (ADS)

This overview of near-IR studies of symbiotic stars gives consideration to helium and oxygen lines in hot stars, near-IR spectra in cool stars, and nebular lines. Also examined are spectra in the range 8000-11,000 A for the following stars: RY Sct, EG And, CH Cyg, CI Cyg, AG Dra, AG Peg, RX Pup, V1016 Cyg, HM Sge, and HBV 475. It is noted that symbiotic stars simultaneously display the spectral characteristics of hot stars, cool stars (mainly of M type), nebulae, and circumstellar dust envelopes.

Andrillat, Y.

320

Micro-Raman spectra of ugrandite garnet.  

PubMed

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

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

2009-08-01

321

Electronic absorption spectra of lunar minerals  

NASA Technical Reports Server (NTRS)

Techniques for obtaining information on the crystal chemistry of transition-metal ions from measurement of the electronic absorption spectra of lunar minerals are reviewed along with the theory of spectral interpretation. Typical polarized absorption spectra are examined for lunar pyroxenes, pyroxferroite, olivine, and plagioclase feldspars. Oxidation states of Fe, Ti, and Cr in lunar minerals are discussed, and conditions under which they crystallized are considered. It is shown how information on the gross mineralogy and petrology of different regions of the moon's surface may be extracted from remote reflectivity measurements of that surface.

Vaughan, D. J.; Burns, R. G.

1977-01-01

322

Analytical calculation of two-dimensional spectra.  

PubMed

We demonstrate an analytical calculation of two-dimensional (2D) coherent spectra of electronic or vibrational resonances. Starting with the solution to the optical Bloch equations for a two-level system in the 2D time domain, we show that a fully analytical 2D Fourier transform can be performed if the projection-slice and Fourier-shift theorems of Fourier transforms are applied. Results can be fit to experimental 2D coherent spectra of resonances with arbitrary inhomogeneity. PMID:25831281

Bell, Joshua D; Conrad, Rebecca; Siemens, Mark E

2015-04-01

323

Mass spectra interpretation of some thiophosphororganic compounds  

NASA Astrophysics Data System (ADS)

The fragmentation pattern of six thiophosphonic-amyd-aryl-sulphonimido derivatives is presented. The electron impact mass spectra were recorded at 70 eV. High resolution mass measurements and metastable analyses were performed to elucidate the ions composition and the fragmentation processes.

Moldovan, Z.; Nicoara, S.; Culea, M.; Cozar, O.; Fenesan, I.; Vegh, P.; Rios, J. J.

1995-03-01

324

Wavelength Calibration of Near-Infrared Spectra  

Microsoft Academic Search

An atlas of a thorium-argon hollow cathode lamp in selected intervals of the 1-2.5 mum region is presented. Accurate wavelengths of the ~500 lines recorded are given in a table. This material is intended for wavelength calibration of near-infrared spectra and is especially critical for high-resolution work.

Kenneth H. Hinkle; Richard R. Joyce; Abigail Hedden; Lloyd Wallace; Rolf Engleman Jr.

2001-01-01

325

Spectra of Angrites and Possible Parent Bodies  

NASA Technical Reports Server (NTRS)

One meteorite class where very little progress has been made in identifying possible parent bodies is the angrites. We have obtained spectra of two new angrites (D'Orbigny and Sahara 99555). Additional information is contained in the original extended abstract.

Burbine, T. H.; McCoy, T. J.; Binzel, R. P.

2001-01-01

326

Scaling of vertical temperature gradient spectra  

Microsoft Academic Search

Tests of a formula derived for the cutoff wave number of vertical temperature gradient spectra, using data taken in the upper layers of the North Pacific, show encouraging results. To derive this formula, the cutoff wave number is assumed to be the Batchelor wave number, with kinetic energy dissipation calculated by combining a form used in the atmosphere for caLculating

D. R. Caldwell; T. M. Dillon; J. M. Brubaker; P. A. Newberger; C. A. Paulson

1980-01-01

327

Temperatures of Fragment Kinetic Energy Spectra  

E-print Network

Multifragmentation reactions without large compression in the initial state (proton-induced reactions, reverse-kinematics, projectile fragmentation) are examined, and it is verified quantitatively that the high temperatures obtained from fragment kinetic energy spectra and lower temperatures obtained from observables such as level population or isotope ratios can be understood in a common framework.

Wolfgang Bauer

1994-11-29

328

Earth and Venus transmission spectra during transit  

E-print Network

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

Widemann, Thomas

329

Microdosimetric spectra measurements of JANUS neutrons  

SciTech Connect

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

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

1985-01-01

330

Submillimeter-wave spectra of hypoiodous acid  

Microsoft Academic Search

Pure rotational spectra of hypoiodous acid, HOI, and its deuterated species, DOI, were measured in the frequency range of 320-670 GHz. The molecule was efficiently produced by a reaction of atomic oxygen with iodoethane. Rotational constants and centrifugal distortion constants for the molecule were determined accurately. The vibrationally averaged structure for HOI was obtained by taking the isotopic difference of

Hiroyuki Ozeki; Shuji Saito

2004-01-01

331

Discriminating Dysarthria Type from Envelope Modulation Spectra  

ERIC Educational Resources Information Center

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

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

2010-01-01

332

The Evolution of the MLLA Parton Spectra  

E-print Network

The evolution with energy scale of the partonic logarithmic scaled energy spectra is investigated in the framework of the modified leading logarithmic approximation (MLLA). The behaviour of the higher order moments is compared to a number of analytic predictions and $\\rm e^+e^-$ data.

N. H. Brook; I. O. Skillicorn

2000-03-10

333

Fitting PAC spectra with a hybrid algorithm  

NASA Astrophysics Data System (ADS)

A hybrid algorithm (HA) that blends features of genetic algorithms (GA) and simulated annealing (SA) was implemented for simultaneous fits of perturbed angular correlation (PAC) spectra. The main characteristic of the HA is the incorporation of a selection criterion based on SA into the basic structure of GA. The results obtained with the HA compare favorably with fits performed with conventional methods.

Alves, M. A.; Carbonari, A. W.

334

Fitting PAC spectra with a hybrid algorithm  

NASA Astrophysics Data System (ADS)

A hybrid algorithm (HA) that blends features of genetic algorithms (GA) and simulated annealing (SA) was implemented for simultaneous fits of perturbed angular correlation (PAC) spectra. The main characteristic of the HA is the incorporation of a selection criterion based on SA into the basic structure of GA. The results obtained with the HA compare favorably with fits performed with conventional methods.

Alves, M. A.; Carbonari, A. W.

2008-01-01

335

The energy spectra of solar flare electrons  

Microsoft Academic Search

A survey of 50 electron energy spectra from .1 to 100 MeV originating from solar flares was made by the combination of data from two spectrometers onboard the International Sun Earth Explorer-3 spacecraft. The observed spectral shapes of flare events can be divided into two classes through the criteria of fit to an acceleration model. This standard two step acceleration

P. A. Evenson; D. Hovestadt; P. Meyer; D. Moses

1985-01-01

336

Calculated late time spectra of supernovae  

SciTech Connect

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

Axelrod, T.S.

1987-10-30

337

Isotopically resolved Raman spectra of C60  

Microsoft Academic Search

We present high-resolution Raman spectra of C60 molecules. The totally symmetric mode near 1470 cm-1 shows a fine structure which is almost exactly isomorphic with the mass spectrum of the molecule. We show that this surprising result can be explained in terms of isotopically induced frequency shifts and the unique icosahedral symmetry of the molecule. A comparison of predicted and

S. Guha; J. Menéndez; J. B. Page; G. B. Adams; G. S. Spencer; J. P. Lehman; P. Giannozzi; S. Baroni

1994-01-01

338

Vacuum ultraviolet spectra of carbonaceous chondrites  

Microsoft Academic Search

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

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

1978-01-01

339

Variations on supersymmetry breaking and neutrino spectra  

SciTech Connect

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

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

2000-12-11

340

Principal component analysis of phenolic acid spectra  

Technology Transfer Automated Retrieval System (TEKTRAN)

Phenolic acids are common plant metabolites that exhibit bioactive properties and have applications in functional food and animal feed formulations. The ultraviolet (UV) and infrared (IR) spectra of four closely related phenolic acid structures were evaluated by principal component analysis (PCA) to...

341

Astronomy Spectra Experiment for Nonscience Students.  

ERIC Educational Resources Information Center

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

Kaufman, S. E.

1982-01-01

342

Determinations of photon spectra. Master's thesis  

SciTech Connect

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

Wannigman, D.L.

1989-01-01

343

Strain-fluctuation effect on Raman spectra  

Microsoft Academic Search

We show that the interaction of phonons with static strain fluctuations induces an inhomogeneous shift and a broadening of Raman spectra. The Raman scattering cross section is calculated in terms of the averaged strain, which relaxes smoothly in real space, and of the strain correlation function. Two regimes of short- and long-range disorder with different line shapes are found. The

L. A. Falkovsky; J. M. Bluet; J. Camassel

1997-01-01

344

Chaotic spectra: How to extract dynamic information  

SciTech Connect

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

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

1988-10-01

345

Disk-averaged synthetic spectra of Mars  

E-print Network

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-curves and the spectral variability at visible + mid-IR wavelengths for Mars as a function of viewing angle, illumination, season. We also considered the appearance of an increasingly frozen Mars and simulated its detection versus real Mars with TPF-C and TPF-I as a function of spectral resolving power, signal-to-noise, integration time.

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

2004-08-20

346

Near Infrared Spectra from Type Ia Supernova  

NASA Astrophysics Data System (ADS)

We present eleven near infrared (NIR) spectra from Type Ia supernovae (SNe Ia). Each spectrum covers the range 0.80-2.50/mu with a resolution of 1200, 750 or 250. The images were obtained using the SpeX instrument at the NASA Infrared Telescope Facility (IRTF). The temporal range of the spectra is from two days before maximum light to eighteen days after. Our detailed models of SNe Ia explosions provide line identifications for the spectral features at all epochs. Type Ia supernovae are excellent probes of the universe at great distance due to their tremendous brightness and apparent homogeneity. The NIR between 0.8? and 2.5? is optimal for examining certain products of the SN Ia explosion that may be blended or obscured in other spectral regions. Observations in these other spectral regimes fail to resolve many questions about the nature of the progenitors, the explosion mechanism, and dynamics of SNe Ia. NIR analysis can provide significant new constraints on SNe Ia physics. It will also contribute to understanding the systematics and calibration of the high-z supernova data. The models utilize hydrodynamic simulations of the explosion and a radiation transport code for the nucleosynthesis that have been very successful in making predictions and analyzing the optical (Höflich & Khokhlov 1996) and infrared (Meikle, et al., 1996, Höflich, et al., 2001) behavior of SNe Ia. Our program compares the spectra obtained at the IRTF to synthetic spectra produced by our models.

Marion, G. H.; Höflich, P.; Vacca, W. D.; Wheeler, J. C.

2002-05-01

347

Cytochrome Difference Spectra of Acetic Acid Bacteria  

Microsoft Academic Search

The cytochrome difference spectra of 15 strains of the genus Acetobacter were found to differ from those of 7 strains of the genus Gluconobacter. The Acetobacter strains contained cytochrome al , which was lacking in the Gluconobacter strains. Within the genus A cetobacter, the Peroxydans group of Frateur could be separated through its cytochrome d content from the Oxydans and

BRIGITTE BACHI; L. ETTLINGER

348

Correlation Functions Aid Analyses Of Spectra  

NASA Technical Reports Server (NTRS)

New uses found for correlation functions in analyses of spectra. In approach combining elements of both pattern-recognition and traditional spectral-analysis techniques, spectral lines identified in data appear useless at first glance because they are dominated by noise. New approach particularly useful in measurement of concentrations of rare species of molecules in atmosphere.

Beer, Reinhard; Norton, Robert H., Jr.

1989-01-01

349

Interpretation of Infrared Spectra, A Practical Approach  

NSDL National Science Digital Library

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

John Coates

350

[Characteristics analysis of human tongue reflectance spectra].  

PubMed

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

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

2014-08-01

351

[Characteristics analysis of human tongue reflectance spectra].  

PubMed

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

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

2014-08-01

352

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

353

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

NASA Astrophysics Data System (ADS)

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

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

2006-02-01

354

LMM Auger primary excitation spectra of copper  

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

355

An Interactive Gallery of Planetary Nebula Spectra  

NASA Astrophysics Data System (ADS)

We have created a website containing high-quality moderate-resolution spectra of 88 planetary nebulae (PNe) from 3600 to 9600 Å, obtained at KPNO and CTIO. Spectra are displayed in a zoomable window, and there are templates available that show wavelength and ion identifications. 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, and a table with atlas information for each object along with a link to an image. This table can be re-ordered by object name, galactic or equatorial coordinates, distance from the sun, the galactic center, or the galactic plane. We envision that this website, which concentrates a large amount of data in one place, will be of interest to a variety of users. PN 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 encourage such use, we have written two simple exercises at a basic level to introduce beginning astronomy students to the wealth of information that PN spectra contain. We are grateful to Adam Wang of the Williams College OIT and to his summer student teams who worked on various apects of the implementation of this website. This work has been supported by NSF grant AST-9819123 and by Williams College and the University of Oklahoma.

Kwitter, K. B.; Henry, R. B. C.

2002-12-01

356

Improved predictions of reactor antineutrino spectra  

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

357

Spectra of porphyrins XI. Absorption and fluorescence spectra of matrix isolated phthalocyanines  

Microsoft Academic Search

Absorption and fluorescence spectra of free base and zine phthalocyanines (H2Pc and ZnPc) were studied in matrices of Ar, Kr, Xe, CH4, N2, and SF6 at liquid hydrogen temperature. ZnPc was also studied in CO. The spectra show considerable fine structure whose resolution decreases along the series Ar > CH4 >~ Kr >~ Xe > N2 >~ SF6 > CO.

Larry Bajema; Martin Gouterman; Beat Meyer

1968-01-01

358

Electric field representation of pulsar intensity spectra  

E-print Network

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

Mark Walker; Dan Stinebring

2005-08-08

359

Analysis of spectra using correlation functions  

NASA Technical Reports Server (NTRS)

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.

Beer, Reinhard; Norton, Robert H.

1988-01-01

360

Primordial power spectra from anisotropic inflation  

SciTech Connect

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

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

2010-05-15

361

Raman spectra of deuteriated taurine single crystals  

NASA Astrophysics Data System (ADS)

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

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

2005-05-01

362

Slovak video meteor network --- meteor spectra  

NASA Astrophysics Data System (ADS)

After the great success of the All-Sky Meteor Orbit System (AMOS) [1,2], we upgraded the system by adding the AMOS-Spec camera for recording meteor spectra. The long-term AMOS-Spec program aims to measure the main element abundances of meteors detected by AMOS. Installed at the Modra Observatory station, the camera is based on the AMOS camera, equipped with 30~mm f/3.5 lens and 500 grooves/mm grating. Having the trajectory and orbit from AMOS and merging it with the simultaneously measured spectrum from AMOS-Spec allows us to identify the source of the meteoroid. Here, we report on preliminary results from a sample of meteor spectra collected by the AMOS-Spec camera since November 2013. The figure shows an example emission spectrum produced by the sigma Hydrid captured by the AMOS-Spec camera on December 4, 2013.

Rudawska, R.; Tóth, J.; Kalman?ok, D.; Zigo, P.

2014-07-01

363

Inflation and alternatives with blue tensor spectra  

NASA Astrophysics Data System (ADS)

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.

Wang, Yi; Xue, Wei

2014-10-01

364

Cathodoluminescence spectra of gallium nitride nanorods  

PubMed Central

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

2011-01-01

365

Nuclear structure insights into reactor antineutrino spectra  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

366

Specific heat spectra for quasiperiodic ladder sequences  

NASA Astrophysics Data System (ADS)

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.

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

2006-12-01

367

Ab initio infrared and Raman spectra  

NASA Technical Reports Server (NTRS)

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.

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

1983-01-01

368

Fitting the HiRes Spectra  

E-print Network

We fit the HiRes ultra-high energy cosmic ray (UHECR) spectrum measurements with broken power laws in order to identify features. These fits find the previously observed feature known as the Ankle at 10**18.5 eV, as well as evidence for a suppression at higher energies, above 10**19.8 eV. We use the integral spectrum and the E_1/2 test to identify this high energy suppression with the GZK suppression. Finally, we use a model of uniformly distributed extragalactic proton sources together with a phenomenological model of the galactic cosmic ray spectrum to compare the HiRes spectra to what should be expected from the GZK suppression, and to measure how the extragalactic sources must evolve and what the input spectral slope must be to fit the HiRes data. Fits using updated spectra will be presented in Pune.

D. R. Bergman; for the HiRes Collaboration

2005-07-20

369

Multiphoton effects in coherent radiation spectra  

E-print Network

At measurements of gamma-radiation spectra from ultra-relativistic electrons in periodic structures, pileup of events in the calorimeter may cause significant deviation of the detector signal from the classically evaluated spectrum. That requires appropriate resummation of multiphoton contributions. We describe the resummation procedure for the photon spectral intensity and for the photon multiplicity spectrum, and apply it to the study of spectra of coherent radiation with an admixture of incoherent component. Impact of multiphoton effects on the shape of the radiation spectrum is investigated. The limit of high photon multiplicity for coherent radiation is explored. A method for reconstruction of the underlying single-photon spectrum from the multiphoton one is proposed.

Bondarenco, M V

2013-01-01

370

Magnetic pressure support and accretion disk spectra  

E-print Network

Stellar atmosphere models of ionized accretion disks have generally neglected the contribution of magnetic fields to the vertical hydrostatic support, although magnetic fields are widely believed to play a critical role in the transport of angular momentum. Simulations of magnetorotational turbulence in a vertically stratified shearing box geometry show that magnetic pressure support can be dominant in the upper layers of the disk. We present calculations of accretion disk spectra that include this magnetic pressure support, as well as a vertical dissipation profile based on simulation. Magnetic pressure support generically produces a more vertically extended disk atmosphere with a larger density scale height. This acts to harden the spectrum compared to models that neglect magnetic pressure support. We estimate the significance of this effect on disk-integrated spectra by calculating an illustrative disk model for a stellar mass black hole, assuming that similar magnetic pressure support exists at all radii.

O. M. Blaes; S. W. Davis; S. Hirose; J. H. Krolik; J. M. Stone

2006-01-17

371

Correcting Infrared Spectra for Atmospheric Transmission  

Microsoft Academic Search

Astronomical spectra taken with ground-based telescopes in the near-IR spectral region are affected by strong absorptions due to molecules in the Earth's atmosphere, particularly CO2 and H2O. These features need to be removed in order to reveal the true spectrum of the object being observed. The traditional technique for doing this is to observe a standard star with a relatively

Jeremy Bailey; Andrew Simpson; David Crisp

2007-01-01

372

Ultraviolet spectra of R Coronae Borealis stars  

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

373

Evolution of Nuclear Spectra with Nuclear Forces  

E-print Network

We first define a series of NN interaction models ranging from very simple to fully realistic. We then present Green's function Monte Carlo calculations of light nuclei to show how nuclear spectra evolve as the nuclear forces are made increasingly sophisticated. We find that the absence of stable five- and eight-body nuclei depends crucially on the spin, isospin, and tensor components of the nuclear force.

R. B. Wiringa; Steven C. Pieper

2002-07-16

374

Neutron leakage spectra from beryllium shells  

SciTech Connect

First results on neutron leakage spectra measurements for eight beryllium spheres with wall thickness from 3.2cm to 19.8cm with 14MeV neutron point source in the center are reported. Brief description of experimental arrangement, time of flight spectrometer, measurements and data reduction procedures are given. Preliminary experimental results are compared with the transport calculations, using the latest versions of evaluated data libraries.

Devkin, B.V.; Kobozev, M.G.; Kuzminov, B.D.; Simakov, S.P.; Sinitsa, V.V. [Institute of Physics and Power Engineering, Obninsk (Russian Federation); Chuvilin, D.Yu.; Zagryadsky, V.A. [Kurchatov Institute of Atomic Energy, Moscow (Russian Federation); Fischer, U.; Wiegner, E. [Kernforschungszentrum, Karlsruhe (Russian Federation)

1994-12-31

375

Infrared spectra of catalysts and adsorbed molecules  

Microsoft Academic Search

1.The IR spectra in the region of 400–4000 cm-1 were studied for pure nickel monoxide hydrate and aluminum hydroxide, as well as mixed hydroxides produced by precipitation with ammonia from solutions of the nitrates.2.The process of formation of nickel-aluminum oxide catalysts during their heat treatment in the interval 50–600° was investigated by the method of IR spectroscopy.3.The existence of a

L. I. Lafer; V. I. Yakerson; N. I. Romanova; V. Ya. Danyushevskii; A. M. Rubinshtein

1971-01-01

376

Dose spectra from energetic particles and neutrons  

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

377

Reanalysis of Tyrannosaurus rex Mass Spectra.  

PubMed

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

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

2009-09-01

378

More Auger photoelectron coincidence spectra from copper  

Microsoft Academic Search

We have recently re-built our Auger photoelectron coincidence spectroscopy (APECS) system at Murdoch University. The new instrument counts at much higher rates and with greater energy resolution. With this we have looked again at the APECS spectra from Cu. We have been able to see more clearly the L2–L3V–VV(V) Coster–Kronig satellite and, in a reverse experiment, to find out which

S. M. Thurgate; C. P. Lund; C. Creagh; R. Craig

1998-01-01

379

Understanding the baryon and meson spectra  

SciTech Connect

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

Pennington, Michael R. [JLAB

2013-10-01

380

Spectra of bigyrotropic magnetic photonic crystals  

Microsoft Academic Search

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

I. L. Lyubchanskii; N. N. Dadoenkova; M. I. Lyubchanskii; E. A. Shapovalov; A. Lakhtakia; T. H. M. Rasing

2004-01-01

381

Spitzer/IRS Spectra of GOODS AGN  

NASA Astrophysics Data System (ADS)

IRS Spectra of GOODS AGN Infrared emission from AGN comes from dust heated by black hole accretion and/or star-formation. Separating the contributions in optical/UV light can be difficult, particularly when obscuration is high; mid-infrared spectra are less affected by obscuration and thus offer diagnostics of the underlying power source(s). We present Spitzer IRS spectra of 10 IR-bright, hard X-ray-selected AGN from the GOODS-North field, spanning the redshift range 0.485Spectra were obtained with the deep Long and Short-Low modules, in exposures of 4-8 hours duration, resulting in a S/N ratio of 8-10 per pixel. The observed PAH features, silicate absorption, and infrared continua offer clues to distinguish reprocessed torus emission from the stellar-heated dust component. Combining with extensive GOODS imaging data at radio, sub-mm, infrared, optical and X-ray wavelengths, we place limits on the star-formation rates, Eddington ratios, and bolometric luminosities of the sample, and compare with lower-redshift samples to probe the evolution of the dust-enshrouded phase of AGN activity. This work was supported by NASA JPL/Spitzer grant RSA 177278. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Support for this work was provided by NASA JPL/Spitzer grant RSA 177278.

Van Duyne, Jeffrey; Urry, C. M.

2006-12-01

382

Fractal Fourier spectra of Cherry flows  

NASA Astrophysics Data System (ADS)

Flows on the 2-torus with points of equilibrium are considered. Numerical observations suggest that, for the case of trajectories with irrational rotation numbers, power spectra are singular continuous. Dynamics is adequately represented by a symbolic sequence built from four symbols with the help of a substitution rule. This rule effectively takes into account the slowing down of the motion during passages near the saddle point and the superexponential scaling of returns onto a secant line.

Zaks, Michael A.

2001-03-01

383

Graph Classification Based on Optimizing Graph Spectra  

Microsoft Academic Search

\\u000a Kernel methods such as the SVM are becoming increasingly popular due to their high performance in graph classification. In\\u000a this paper, we propose a novel graph kernel, called SPEC, based on graph spectra and the Interlace Theorem, as well as an\\u000a algorithm, called OPTSPEC, to optimize the SPEC kernel used in an SVM for graph classification. The fundamental performance\\u000a of

Nguyen Duy Vinh; Akihiro Inokuchi; Takashi Washio

2010-01-01

384

Graph Classification Based on Optimizing Graph Spectra  

NASA Astrophysics Data System (ADS)

Kernel methods such as the SVM are becoming increasingly popular due to their high performance in graph classification. In this paper, we propose a novel graph kernel, called SPEC, based on graph spectra and the Interlace Theorem, as well as an algorithm, called OPTSPEC, to optimize the SPEC kernel used in an SVM for graph classification. The fundamental performance of the method is evaluated using artificial datasets, and its practicality confirmed through experiments using a real-world dataset.

Vinh, Nguyen Duy; Inokuchi, Akihiro; Washio, Takashi

385

Trailed Spectra of Bright Spectrophotometric Standard Stars  

NASA Astrophysics Data System (ADS)

The IUE archives is an extensive and growing database of UV spectra of a wide variety of astronomical objects. The usefulness of the archives will be greatly enhanced by the presence of a number of wellobserved standard stars including those which define the visual wavelength absolute flux calibrations. Observation of ground-based spectrophotometric standards by IUE will be useful for providing a selfconsistent flux calibration for bright stars and for permitting direct comparisons with fainter standards for future missions, already in the archives, on the IUE system. New observing techniques now make it possible for IUE to obtain well-exposed spectra of these bright stars. However, this observing method is one of the few which may not be possible if IUE were to lose another gyro and the backup control mode, now under development, were used. We propose to obtain short and long wavelength spectra for four of the brightest spectrophotometric standard stars which have either not been observed with with IUE or are poorly represented in the IUE archives. Over a number of years these stars have been observed and defined as standards by a number of ground based observers including Oke(1964), Breger (1976), Stone(1977), Oke and Gunn (1983), and Taylor (1984). The primary standard has been Vega with 109 Vir as an alternate (Davis Philip and Hayes 1984). By combining trailed and point source spectra, ultraviolet absolute flux distributions will be obtained for the 1200-3200 A interval. A comparison will be made of Alpha Lyr and 109 Vir with the nearby star Alpha CMA A, which has a well-determined distance and measured radius. The suspected low-level intermittent variability of Alpha Lyr is not believed to pose major problems for our analysis.

Pitts, Ronald E.

386

Deconvolution of diode-laser spectra  

NASA Technical Reports Server (NTRS)

A new technique has been developed for deconvolving diode-laser spectra. This technique treats Doppler broadening, collisional broadening, and instrumental effects simultaneously. This technique is superior to previous deconvolution methods in the recovery of line-strength and transition-frequency information. A section of the ethane spectrum near 12 microns is used as an example. This new approach applies to any spectroscopy in which the instrumental resolution is narrower than actual linewidths.

Halsey, G. W.; Jennings, D. E.; Blass, W. E.

1985-01-01

387

Dynamical analysis of highly excited molecular spectra  

SciTech Connect

The goal of this program is new methods for analysis of spectra and dynamics of highly excited vibrational states of molecules. In these systems, strong mode coupling and anharmonicity give rise to complicated classical dynamics, and make the simple normal modes analysis unsatisfactory. New methods of spectral analysis, pattern recognition, and assignment are sought using techniques of nonlinear dynamics including bifurcation theory, phase space classification, and quantization of phase space structures. The emphasis is chaotic systems and systems with many degrees of freedom.

Kellman, M.E. [Univ. of Oregon, Eugene (United States)

1993-12-01

388

Deconvolution of spectra for intimate mixtures  

NASA Technical Reports Server (NTRS)

Visible to near infrared reflectance spectra of macroscopic mixtures have been shown to be linear combinations of the reflections of the pure mineral components in the mixture. However, for microscopic mixtures the mixing systematics are in general nonlinear. The systematics may be linearized by conversion of reflectance to single scattering albedo (w), where the equations which relate reflectance to w depend on the method of data collection. Several proposed mixing models may be used to estimate mineral abundances from the reflectance spectra of intimate mixtures. These models are summarized and a revised model is presented. A noniterative (linear) least squares approach was used for curve fitting and the data, measured as bi-directional reflectance with incidence and emergence angles of 30 and 0 deg were converted to w by a simplified version of Hapke's equation for bi-directional reflectance. This model was tested with two mixture series composed of 45 to 75 micron particles: an anorthite-enstatite series and an olivine-magnetite series. The data indicate that the simplified Hapke's equation may be used to convolve reflectance spectra into mineral abundances if appropriate endmembers are known or derived from other techniques. For surfaces that contain a significant component of very low albedo material, a somewhat modified version of this technique will need to be developed. Since the abundances are calculated using a noniterative approach, the application of this method is especially efficient for large spectral data sets, such as those produced by mapping spectrometers.

Mustard, John F.; Pieters, Carle M.; Pratt, Stephen F.

1987-01-01

389

IRAS Low Resolution Spectra of Asteroids  

NASA Technical Reports Server (NTRS)

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

Cohen, Martin; Walker, Russell G.

2002-01-01

390

Modelling Plerion Spectra and their Evolution  

E-print Network

We review recent theoretical developments on pulsar winds, their nebulae and relativistic shock acceleration, and show how they illuminate unsolved problems in plerion spectra, in particular the multiple spectral breaks in the Crab and the low-frequency breaks of plerions such as G 21.5-0.9 and 3C 58. Recent work on Fermi acceleration theory at relativistic shocks shows that a particle spectral index of 2.2-2.3, compatible with the X-ray spectra of plerions, results under a wide variety of assumptions. If pulsar winds contain ions as well as electrons and positrons, the mechanism of Hoshino et al. (1992), which yields harder spectra, would operate at lower energies and may explain the flat radio spectral indices of plerions. This scenario implies wind parameters in the Crab compatible with the pulsar wind acceleration model of Lyubarsky & Kirk (2001). Recent hydrodynamical simulations of plerion evolution inside SNR blast waves demonstrate that the passage of the reverse shock rapidly compresses the plerion. Using a simple isobaric model, we investigate the influence of the resulting magnetic field compression and decrease in shock radius on the evolution of the plerion spectrum. We suggest that the passage of the reverse shock may explain the low-frequency breaks in 3C 58 and G 21.5-0.9, as well as the increase in 3C 58's radio flux.

Yves A. Gallant; Eric van der Swaluw; John G. Kirk; Abraham Achterberg

2001-12-14

391

Infrared Transmission Spectra for Extrasolar Giant Planets  

NASA Astrophysics Data System (ADS)

Among the hot Jupiters known to date that transit their parent stars, the two best candidates to be observed with transmission spectroscopy in the mid-infrared (MIR) are HD 189733b and HD 209458b, due to their combined characteristics of planetary density, orbital parameters, and parent star distance and brightness. Here we simulate transmission spectra of these two planets during their primary transit in the MIR, and we present sensitivity studies of the spectra to the changes of atmospheric thermal properties, molecular abundances, and C/O ratios. Our model predicts that the dominant species absorbing in the MIR on hot Jupiters are water vapor and carbon monoxide, and their relative abundances are determined by the C/O ratio. Since the temperature profile plays a secondary role in the transmission spectra of hot Jupiters compared to molecular abundances, future primary transit observations in the MIR of those objects might offer insight on extrasolar giant planet atmospheric chemistry. We find here that the absorption features caused by water vapor and carbon monoxide in a cloud-free atmosphere are deep enough to be observable by the present and future generation of space-based observatories, such as Spitzer Space Telescope and James Webb Space Telescope. We discuss our results in light of the capabilities of these telescopes.

Tinetti, Giovanna; Liang, Mao-Chang; Vidal-Madjar, Alfred; Ehrenreich, David; Lecavelier des Etangs, Alain; Yung, Yuk L.

2007-01-01

392

Secondary charged particle spectra and kerma calculations  

SciTech Connect

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

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

1985-09-16

393

DYNAMICAL ANALYSIS OF HIGHLY EXCITED MOLECULAR SPECTRA  

SciTech Connect

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

Michael E. Kellman

2005-06-17

394

VARIABILITY IN OPTICAL SPECTRA OF {epsilon} ORIONIS  

SciTech Connect

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.

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

395

Optical spectra analysis for breast cancer diagnostics  

NASA Astrophysics Data System (ADS)

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.

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

2011-11-01

396

Analysis of positron lifetime spectra in polymers  

NASA Technical Reports Server (NTRS)

A new procedure for analyzing multicomponent positron lifetime spectra in polymers was developed. It requires initial estimates of the lifetimes and the intensities of various components, which are readily obtainable by a standard spectrum stripping process. These initial estimates, after convolution with the timing system resolution function, are then used as the inputs for a nonlinear least squares analysis to compute the estimates that conform to a global error minimization criterion. The convolution integral uses the full experimental resolution function, in contrast to the previous studies where analytical approximations of it were utilized. These concepts were incorporated into a generalized Computer Program for Analyzing Positron Lifetime Spectra (PAPLS) in polymers. Its validity was tested using several artificially generated data sets. These data sets were also analyzed using the widely used POSITRONFIT program. In almost all cases, the PAPLS program gives closer fit to the input values. The new procedure was applied to the analysis of several lifetime spectra measured in metal ion containing Epon-828 samples. The results are described.

Singh, Jag J.; Mall, Gerald H.; Sprinkle, Danny R.

1988-01-01

397

Haloes Seen In UVIS Reflectance Spectra  

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

398

Quantization of Entropy Spectra of Black Holes  

NASA Astrophysics Data System (ADS)

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

Kwon, Yongjoon; Nam, Soonkeon

2013-02-01

399

Quantization of Entropy Spectra of Black Holes  

NASA Astrophysics Data System (ADS)

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

Kwon, Yongjoon; Nam, Soonkeon

2015-01-01

400

Soil emissivity and reflectance spectra measurements  

SciTech Connect

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

Sobrino, Jose A.; Mattar, Cristian; Pardo, Pablo; Jimenez-Munoz, Juan C.; Hook, Simon J.; Baldridge, Alice; Ibanez, Rafael

2009-07-01

401

Diffuse interstellar bands in RAVE survey spectra  

NASA Astrophysics Data System (ADS)

We have used spectra of hot stars from the RAVE Survey in order to investigate the visibility and properties of five diffuse interstellar bands previously reported in the literature. The RAVE spectroscopic survey for Galactic structure and kinematics records CCD spectra covering the 8400-8800 Å wavelength region at 7500 resolving power. The spectra are obtained with the UK Schmidt at the AAO, equipped with the 6dF multi-fiber positioner. The DIB at 8620.4 Å is by far the strongest and cleanest of all DIBs occurring within the RAVE wavelength range, with no interference by underlying absorption stellar lines in hot stars. It correlates so tightly with reddening that it turns out to be a reliable tool to measure it, following the relation EB-V = 2.72 (± 0.03)× EW~(Å), valid throughout the general interstellar medium of our Galaxy. The presence of a DIB at 8648 Å is confirmed. Its intensity appears unrelated to reddening, in agreement with scanty and preliminary reports available in the literature, and its measurability is strongly compromised by severe blending with underlying stellar He I doublet at 8649 Å. The two weak DIBs at 8531 and 8572 Å do not appear real and should actually be blends of underlying stellar lines. The very weak DIB at 8439 Å cannot be resolved within the profile of the much stronger underlying hydrogen Paschen 18 stellar line. Table 1 is only available in electronic form at http://www.aanda.org

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

2008-09-01

402

Infrared Divergence in Pseudo-Particle Spectra  

NASA Astrophysics Data System (ADS)

Infrared divergence in the pseudo-particle spectra of the degenerate impurity Anderson model described in terms of the auxiliary particles is examined rigorously with use of the expansion from the large limit of the spin-orbital degeneracy N. The results of analysis with the most divergent terms in the expansion confirm the exponents of the spectra of the slave boson and the pseudo-fermion to be given respectively by 1-nf2/N and (2nf-nf2)/N where nf is the average number of localized electrons at the impurity site, rather than by N/(N+1) and 1/(N+1) as suggested by the results of so-called non-crossing approximation (NCA) studies. In determination of the correct exponents, contributions from the crossing diagrams are crucial. It is also confirmed that all of the infrared divergences in the single particle spectra are cancelled out by the corresponding vertex corrections to leave only non-divergent terms in the scattering rate of the conduction electrons.

Matsuura, Tamifusa; Tsuruta, Atsushi; ?no, Yoshiaki; Kuroda, Yoshihiro

1997-05-01

403

MAGNETIC ENERGY SPECTRA IN SOLAR ACTIVE REGIONS  

SciTech Connect

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

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

2010-09-01

404

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 ...

405

Infrared absorption spectra, radiative efficiencies, and global warming potentials  

E-print Network

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

Wirosoetisno, Djoko

406

Study on Mössbauer spectra of hemoglobin in thalassemia  

NASA Astrophysics Data System (ADS)

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

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

1988-02-01

407

Quantum synchrotron spectra from semirelativistic electrons in teragauss magnetic fields  

NASA Technical Reports Server (NTRS)

Synchrotron spectra are calculated from quantum electrodynamic transition rates for thermal and power-law electron distributions. It is shown that quantum effects appear in thermal spectra when the photon energy is greater than the electron temperature, and in power-law spectra when the electron energy in units of the electron rest mass times the magnetic field strength in units of the critical field strength is of order unity. These spectra are compared with spectra calculated from the ultrarelativistic approximation for synchrotron emission. It is found that the approximation for the power-law spectra is good, and the approximation for thermal spectra produces the shape of the spectrum accurately but fails to give the correct normalization. Single photon pair creation masks the quantum effects for power-law distributions, so only modifications to thermal spectra are important for gamma-ray bursts.

Brainerd, J. J.

1987-01-01

408

Identifying Minerals from Their Infra-red Spectra.  

ERIC Educational Resources Information Center

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)

Paterson, W. G.

1986-01-01

409

Proposed reference irradiance spectra for solar energy systems testing  

Microsoft Academic Search

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

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

2002-01-01

410

Atlas of Synthetic Ultraviolet Spectra of Massive Star Populations  

Microsoft Academic Search

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,

Claus Leitherer; Carmelle Robert; Timothy M. Heckman

1995-01-01

411

Synthetic UV spectra of massive stars (Leitherer+ 1995)  

Microsoft Academic Search

An atlas of synthetic ultraviolet spectra of a population of massive stars is presented. The spectra are based on a stellar library of IUE 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 lambda 1240, Si IV lambda 1400, C IV lambda 1550,

C. Leitherer; C. Robert; T. M. Heckman

1996-01-01

412

SAR-ocean wave inversion using image cross spectra  

Microsoft Academic Search

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

Geir Engen; Harald Johnsen

1995-01-01

413

Synthesized Spectra of Optically Thin Emission Lines  

NASA Astrophysics Data System (ADS)

In recent years realistic 3D numerical models of the solar atmosphere have become available. The models attempt to recreate the solar atmosphere and mimic observations in the best way, in order to make it possible to couple complicated observations with physical properties such as the temperatures, densities, velocities, and magnetic fields. We here present a study of synthetic spectra created using the Bifrost code in order to assess how well they fit with previously taken solar data. A study of the synthetic intensity, nonthermal line widths, Doppler shifts, and correlations between any two of these three components of the spectra first assuming statistical equilibrium is made, followed by a report on some of the effects nonequilibrium ionization will have on the synthesized spectra. We find that the synthetic intensities compare well with the observations. The synthetic observations depend on the assumed resolution and point-spread function (PSF) of the instrument, and we find a large effect on the results, especially for intensity and nonthermal line width. The Doppler shifts produce the reported persistent redshifts for the transition region (TR) lines and blueshifts for the upper TR and corona lines. The nonthermal line widths reproduce the well-known turnoff point around (2-3) × 105 K, but with much lower values than those observed. The nonthermal line widths tend to increase with decreasing assumed instrumental resolution, also when nonequilibrium ionization is included. Correlations between the nonthermal line width of any two TR line studies as reported by Chae et al. are reproduced, while the correlations of intensity to line width are reproduced only after applying a PSF to the data. Doppler shift correlations reported by Doschek for the TR lines and correlations of Doppler shift to nonthermal line width of the Fe xii19.5 line reported by Doschek et al. are reproduced.

Olluri, K.; Gudiksen, B. V.; Hansteen, V. H.; De Pontieu, B.

2015-03-01

414

Effect of Temperature on Jet Velocity Spectra  

NASA Technical Reports Server (NTRS)

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

Bridges, James E.; Wernet, Mark P.

2007-01-01

415

Evolution of Fourier spectra through interplanetary shocks  

NASA Astrophysics Data System (ADS)

Well established nearly isothermic solar wind expansion requires an additional heating. A dissipation of large scale variations of the solar wind kinetic energy into the thermal energy via turbulence cascades is thought to be an important source of this heating, although the exact mechanism is yet to be found. For this reason, the turbulence in the solar wind is a subject of extensive theoretical and experimental studies on different time scales ranging from years to minutes. The frequency spectrum of magnetic field fluctuations can be divided into several domains differing by spectral indices - the lowest frequencies are controlled by the solar activity, MHD activity shapes the spectrum at higher (up to 0.1 Hz) frequencies, whereas the ion and electron kinetic effects dominate at the high frequency end of the spectra. Interplanetary shocks of various origins are a part of solar wind turbulence naturally occurring in the solar wind and the BMSW instrument onboard the Spektr-R spacecraft has detected tens of them in course of the 2011-2013 years. Based on its high-time resolution of the ion flux, density and velocity measurements reaching 31 ms, we study an evolution of the frequency spectra on MHD and kinetic scales across fast forward low Mach number shocks. We have found that the power of downstream fluctuations rises by an order of magnitude in a broad range of frequencies independently of its upstream value but the slope of the spectrum on the kinetic scale (?3-8 Hz) has been found to be statistically steeper downstream than upstream of the shock. The time needed to a full relaxation to the pre-shock spectral shape is as long as several hours. A combination of the ion flux power spectra obtained by BMSW with fast magnetic field observations of other spacecraft enhances our understanding of dissipation mechanisms.

Pitna, Alexander; Safrankova, Jana; Nemecek, Zdenek; Nemec, Frantisek; Goncharov, Oleksandr

2014-05-01

416

Near-Infrared Spectra of Supernovae  

NASA Astrophysics Data System (ADS)

We present results from a survey of the near-infrared properties of all types of supernovae. Near-infrared spectra of the subluminous Type Ia SN 1999by taken 5 days before to two weeks after maximum light have been analysed using self-consistent SN Ia explosion models. The data generally agree with 1D delayed-detonation models, indicate a near Chandrasekhar-mass WD progenitor, and show low yield of iron-peak elements confined to the innermost layers of the ejecta. This puts strong constraints on the mixing of large iron blobs into the outer layers due to Rayleigh-Taylor instabilities during the deflagration phase. NIR spectra of Type IIP SNe are relatively line-free during the plateau phase, showing largely hydrogen emission with only a handful of other lines, mostly in the 1-1.2 micron region. After the plateau phase, Type IIP spectra become much richer, showing many overlapping emission features throughout the near-infrared. It appears that CO emission is a common feature of core-collapse supernovae, as several detections of first overtone CO emission near 2.3 microns have been made, including SN 1998S (IIn), SN 1999em, SN 1999gi (IIP) and SN 2000ew (Ic). Finally, we find that Type IIn supernovae often exhibit extraordinary infrared excesses at late times. This is probably thermal emission from hot dust, most likely in the dense circumstellar gas surrounding the progenitor star. The infrared luminosity can reach 1041-42 erg s-1, and can last for several years. A possible scenario is that the dust emission is an ``infrared echo'' powered not by the flash of the SN explosion, but rather by UV/X-ray emission from the strong shock interaction with the dense circumstellar material.

Gerardy, C. L.; Fesen, R. A.; Hoflich, P.; Nomoto, K.; Garnavich, P. M.; Jha, S.; Challis, P. M.; Kirshner, R. P.; Wheeler, J. C.; Sakai, S.

2001-12-01

417

Correcting second-order contamination in low-resolution spectra  

E-print Network

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.

V. Stanishev

2007-05-23

418

High resolution nuclear-magnetic-resonance spectra of hydrocarbon groupings  

Microsoft Academic Search

The interpretation of ABC-type spectra is discussed in relation to several series of calculated spectra; some frequency and intensity sum rules are indicated. The hydrogen spectra of some vinyl derivatives, X. CH = CH2 (X = F, Cl, Br, O and C) have been analysed. It is shown that and that a modified correlation holds between the Jgem coupling constants

C. N. Banwell; N. Sheppard

1960-01-01

419

Classification of prostate magnetic resonance spectra using support vector machine  

E-print Network

that nuclear magnetic resonance spectra are sensitive enough to distinguish normal and cancer. In this paperClassification of prostate magnetic resonance spectra using support vector machine S. Parfait a, we propose a classification technique of spectra from magnetic resonance spectroscopy. We studied au

420

Ris-M-2897 Procedures to Analyse 7-ray Spectra  

E-print Network

Risø-M-2897 Procedures to Analyse 7-ray Spectra Obtainedfromthe ORTEC or Nuclear Data ND-680 System instruments but recorded on a disc as the transfer medium, 2. the -y-spectra obtained from die Nuclear Data ND National Laboratory, DK-4000 Roskilde, Denmark January 1990 #12;Procedures to Analyse 7-ray Spectra

421

Carbon13 nuclear magnetic resonance spectra of keto steroids  

Microsoft Academic Search

Fourier transform C-13 nuclear magnetic resonance spectra were obtained ; and assigned for a complete series of keto steroids -the steroid skeletons being ; those of androstane and cholestane. The assignments were performed by comparing ; the spectra of these closely related compounds and correlating the shifts due to ; differences in structure, and by use of off-resonance decoupled spectra.

Hanne Eggert; Carl Djerassi

1973-01-01

422

Infrared absorption spectra, radiative efficiencies, and global warming potentials  

E-print Network

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

Wirosoetisno, Djoko

423

THE SPECTRA OF THE DOUBLY AND TRIPLY IONIZED RARE EARTHS  

Microsoft Academic Search

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

G. H. Dieke; H. M. Crosswhite

1963-01-01

424

Glow Sticks: Spectra and Color Mixing  

NASA Astrophysics Data System (ADS)

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

Birriel, Jennifer; Birriel, Ignacio

2014-10-01

425

Exclusion Statistics in Conformal Field Theory Spectra  

SciTech Connect

We propose a new method for investigating the exclusion statistics of quasiparticles in conformal field theory (CFT) spectra. The method leads to one-particle distribution functions, which generalize the Fermi-Dirac distribution. For the simplest SU(n) invariant CFTs we find a generalization of Gentile parafermions, and we obtain new distributions for the simplest Z{sub N} -invariant CFTs. In special examples, our approach reproduces distributions based on {open_quotes}fractional exclusion statistics{close_quotes} in the sense of Haldane. We comment on applications to fractional quantum Hall effect edge theories. {copyright} {ital 1997} {ital The American Physical Society}

Schoutens, K. [Institute for Theoretical Physics, Valckenierstraat 65, 1018 XE Amsterdam (The Netherlands)] [Institute for Theoretical Physics, Valckenierstraat 65, 1018 XE Amsterdam (The Netherlands)

1997-10-01

426

Systematics of Identified Hadron Spectra at PHENIX  

E-print Network

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.

M. Csanad

2006-03-02

427

Covariance analysis of gamma ray spectra  

SciTech Connect

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.

Trainham, R.; Tinsley, J. [Special Technologies Laboratory of National Security Technologies, LLC, 5520 Ekwill Street, Santa Barbara, California 93111 (United States)

2013-01-15

428

High-energy spectra of atmospheric neutrinos  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

429

Energy Spectra in Rayleigh-Benard Convection  

NASA Astrophysics Data System (ADS)

We present a numerical study of the energy spectra and fluxes in the inertial range of turbulent Rayleigh-Bénard convection for a wide range of Prandtl number. We consider both free-slip and no-slip conditions for our simulation. Our results support the Kolmogorov-Obukhov (KO) scaling for velocity field for zero-Prandtl number and low-Prandtl number (P ll 1) convection. For large Prandtl number (P > 1) convection, the Bolgiano-Obukhov scaling (BO) appears to agree with the numerical results better than the KO scaling. We provide phenomenological arguments for the zero-Prandtl and low-Prandtl number convection.

Verma, Mahendra K.; Mishra, Pankaj; Chandra, Mani; Paul, Supriyo

2011-12-01

430

Nuclear reactor fissile isotopes antineutrino spectra  

E-print Network

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

V. Sinev

2012-07-30

431

Covariance Analysis of Gamma Ray Spectra  

SciTech Connect

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.

Trainham, R.; Tinsley, J.

2013-01-01

432

Applying Zeeman Doppler imaging to solar spectra  

NASA Astrophysics Data System (ADS)

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

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

2004-03-01

433

Benford's law and complex atomic spectra.  

PubMed

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' 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. PMID:18351894

Pain, Jean-Christophe

2008-01-01

434

Benford's law and complex atomic spectra  

NASA Astrophysics Data System (ADS)

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’ 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.

Pain, Jean-Christophe

2008-01-01

435

Ultraviolet Spectra of Normal Spiral Galaxies  

NASA Technical Reports Server (NTRS)

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

Kinney, Anne

1997-01-01

436

Hilbert transform: Applications to atomic spectra  

NASA Astrophysics Data System (ADS)

In many areas of physics, the Kramers-Kronig relations are used to extract information about the real part of the optical response of a medium from its imaginary counterpart. In this paper we discuss an alternative but mathematically equivalent approach based on the Hilbert transform. We apply the Hilbert transform to transmission spectra to find the group and refractive indices of a Cs vapor and thereby demonstrate how the Hilbert transform allows indirect measurement of the refractive index, group index, and group delay while avoiding the use of complicated experimental setups.

Whittaker, Kate A.; Keaveney, James; Hughes, Ifan G.; Adams, Charles S.

2015-03-01

437

SIMULATION OF PARTICLE SPECTRA AT RHIC.  

SciTech Connect

A purely hadronic simulation is performed of the recently reported data from PHOBOS at energies of {radical}s = 56, 130 GeV using the relativistic heavy ion cascade LUCIFER which had previously given a good description of the NA49 inclusive spectra at {radical}s = 17.2 GeV/A. The results compare well with these early measurements at RHIC and indeed successfully predict the increase in multiplicity now seen by PHOBOS and the other RHIC detectors at the nominal maximum energy of {radical}s = 200 GeV/A, suggesting that evidence for quark-gluon matter remains elusive.

KAHANA,D.E.; KAHANA,S.H.

2001-09-04

438

Multifractal spectra in homogeneous shear flow  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

439

Raman spectra and structure of fluoroaluminophosphate glasses  

Microsoft Academic Search

Fluoroaluminophosphate glasses are promising materials for rare earth doping, but their structure is not yet well known. The structural changes which take place in the 39AlF3–11NaF–10LiF–(40?x)(CaF2–MgF2–SrF2–BaF2)–xNaPO3 system, with increasing NaPO3 content (0–15 mol%), have been studied by polarised Raman and also infrared reflectance spectroscopies. The Raman spectra of the glasses, at low-phosphate content, presented a polarised band peaking near 520cm?1,

Lu??s F Santos; Rui M Almeida; Victor K Tikhomirov; Animesh Jha

2001-01-01

440

Solar Doppler shifts - Sources of continuous spectra  

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

441

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

NASA Astrophysics Data System (ADS)

First-principles anharmonic calculations are carried out for the IR and Raman spectra of the C sbnd H stretching bands in butane. The calculations use the Vibrational Self-Consistent Field (VSCF) algorithm. The results are compared with gas-state experiments. Very good agreement between the computed and experimental results is found. Theory is successful also in computing a weak peak which is caused by combination transitions. The B3LYP potential surface is found superior to MP2, though both methods give good accord with experiment. The theoretical results provide an understanding of the role of different modes in the spectra of hydrocarbons.

Pele, Liat; Šebek, Ji?í; Potma, Eric O.; Benny Gerber, R.

2011-10-01

442

Flux Calibration of Medium Resolution Spectra from 300 nm to 2500 nm — Model Reference Spectra and Telluric Correction  

NASA Astrophysics Data System (ADS)

A procedure to obtain reference spectra for flux standard stars from stellar model atmospheres is described. This procedure allows users to derive instrument response curves from 300 nm to 2500 nm. The technique was developed using X-shooter spectra, but is general and can also be applied to higher resolution spectra. In addition an automatic method has been defined to correct for moderate telluric absorption using telluric model spectra with very high spectral resolution that can easily be adapted to observed data.

Moehler, S.; Modigliani, A.; Freudling, W.; Giammichele, N.; Gianninas, A.; Gonneau, A.; Kausch, W.; Lançon, A.; Noll, S.; Rauch, T.; Vinther, J.

2014-12-01

443

Comparison of spectra produced by a deep water wave model to wave spectra gathered during Hurricane Frederic  

E-print Network

COMPARISON OF SPECTRA PRODUCED BY A DEEP WATER WAVE MODEL TO WAVE SPECTRA GATHERED DURING HURRICANE FREDERIC A Thesis by RICHARD LEE EDWARDS Submitted to the Graduate College of Texas AEM University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE May 1981 Major Subject: Oceanography COMPARISON OF SPECTRA PRODUCED BY A DEEP WATER WAVE MODEL TO WAVE SPECTRA GATHERED DURING HURRICANE FREDERIC A Thesis by RICHARD LEE EDWARDS Approved as to style and content by...

Edwards, Richard Lee

1981-01-01

444

Energy Spectra of Developed Turbulencein Helium Superfluids  

E-print Network

We suggest a "minimal model" for the 3D turbulent energy spectra in superfluids, based on their two-fluid description. We start from the Navier-Stokes equation for the normal fluid and from the coarse-grained hydrodynamic equation for the superfluid component (obtained from the Euler equation for the superfluid velocity after averaging over the vortex lines) and introduce a mutual friction coupling term, proportional to the counterflow velocity, the average superfluid vorticity and to the temperature dependent parameter $q=\\alpha/(1+\\alpha')$, where $\\alpha$ and $\\alpha'$ denote the dimensionless parameters characterizing the mutual friction between quantized vortices and the normal component of the liquid. We then derive the energy balance equations, taking into account the cross-velocity correlations. We obtain all asymptotical solutions for normal and superfluid energy spectra for limiting cases of small/big normal to superfluid density ratio and coupling. We discuss the applicability limits of our model to superfluid He II and to $^3$He-B and compare the model predictions with available experimental data.

Victor S. L'vov; Sergei V. Nazarenko; L. Skrbek

2006-06-01

445

Spectra of thermally unstable slim discs  

E-print Network

Thermal instability driven by radiation pressure might be relevant for intrinsically bright accreting sources. The most promising candidate where this instability seems to be at work is one of the two known galactic superluminal sources, GRS 1915+105 (Belloni et al. 1997). In spite of being of relevance, this scenario has not yet been confirmed by proper time-dependent modelling. Non-linear time-dependent calculations performed by Szuszkiewicz and Miller (1998) show that thermally unstable discs undergo limit-cycle behaviour with successive evacuation and refilling of the central parts of the disc. This evolution is very similar to the one proposed by Belloni et al. (1997) in their phenomenological model. Further investigations are needed to confirm the thermal instability being operational in this source. First of all the spectra emitted from the disc during its evolution should be calculated and compared with observations. Here such spectra are computed assuming local blackbody emission from the best studied transonic disc model.

Ewa Szuszkiewicz; Roberto Turolla; Luca Zampieri

2000-11-21

446

Spectra of Cas A's Highest Velocity Ejecta  

NASA Astrophysics Data System (ADS)

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

Fesen, Robert A.; Milisavljevic, Dan

2010-08-01

447

Theory of optical spectra of exciton condensates  

SciTech Connect

We present theoretical calculations of optical absorption-gain spectra for condensed excitons in both three dimensional (3D), 2D, and quasi-2D systems (appropriate for semiconductor quantum wells) as functions of the electron-hole pair density and temperature. The ladder diagram contribution to the vertex function (exciton effect) is included in our calculation. We found that fluctuations cannot destroy the condensation of excitons in 2D at finite temperatures as opposed to a theory of free bosons and the case of Cooper pairs in superconductivity. Such a difference is attributed to the fact that electrons and holes carry opposite charges as opposed to the same charges carried by the Cooper pairs in the case of superconductivity. Our studies show that the effects of exciton Bose condensation on the absorption-gain spectra remain present for temperatures up to 130 K for a 2D system with exciton binding energy of 30{endash}40 meV (appropriate for ZnSe systems). {copyright} {ital 1996 The American Physical Society.}

Chu, H.; Chang, Y.C. [Department of Physics and Materials Research Laboratory, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801-3080 (United States)] [Department of Physics and Materials Research Laboratory, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801-3080 (United States)

1996-08-01

448

Theory of giant planet atmospheres and spectra  

NASA Astrophysics Data System (ADS)

Giant exoplanet atmospheres have now been studied by transit spectroscopy, spectroscopy and photometry at secondary eclipse, photometric light curves as a function of orbital phase, very high-resolution spectroscopic velocity measurements, and high-contrast imaging. Moreover, there is a correspondence between brown dwarf and giant planet atmospheres and spectra that has been profitably exploited for many years to better understand exoplanets. In this presentation, I endeavor to review the information extracted by these techniques about close-in giant exoplanet compositions and temperatures. Then, I will summarize the expected character of the spectra, light curves, and polarizations of the objects soon to be studied using high-contrast imaging by GPI, SPHERE, WFIRST-AFTA, and Subaru/HiCIAO as a function of mass, age, Keplerian elements, and birth properties (such as entropy). The goal will be to frame the theoretical discussion concerning what physical information can be gleaned in the next years about giant planet atmospheres by direct (or almost direct) imaging and characterization campaigns, and their role as stepping stones to the even more numerous sub-Neptunes, super-Earths, and Earths.

Burrows, Adam Seth

2014-06-01

449

Biological NMR FIDs and spectra normalization  

NASA Astrophysics Data System (ADS)

There is increasing use of spectroscopic techniques, such as high-resolution NMR spectroscopy, to examine variations in cell metabolism and / or structure in response to numerous physical, chemical, and biological agents. In these types of studies, in order to obtain relative quantitative information, a comparison between signal intensities of control samples and treated or exposed ones is often conducted. The methods thus far developed for this purpose are not directly related to the overall intrinsic properties of the samples, but rather to the addition of external substances of known concentrations or to indirect measurement of internal substances. Another possibility is to estimate, by an opportune algorithm, a normalization constant which takes into consideration all cell metabolites present in the sample. Recently, a new normalization algorithm, based on Principal Component Analysis (PCA), was presented. PCA is a well-known statistical technique for analysis of large, multivariate datasets, which extracts the basic features of the data. The PRICONA (PRincipal COmponent Normalization Algorithm) algorithm use PCA in a new totally different manner: PCA is, in fact, used to normalize spectra in order to obtain quantitative information about the treatment effects. In this paper, a comparison of results obtained in the time domain, that is on NMR FIDs (Free Induction Decay) and in the frequency domain, on NMR spectra, is conducted. The comparison is useful because in NMR spectroscopy analysis in the different domain can have different advantages. The algorithm was tested by Monte Carlo simulations of NMR FIDs.

Romano, R.; Canonico, R.; Acernese, F.; Giordano, G.; Barone, F.

2014-03-01

450

An atlas of selected calibrated stellar spectra  

NASA Technical Reports Server (NTRS)

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

Walker, Russell G.; Cohen, Martin

1992-01-01

451

SAMPI: Protein Identification with Mass Spectra Alignments  

PubMed Central

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

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

2007-01-01

452

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

NASA Astrophysics Data System (ADS)

The directly measured elemental spectra of primary cosmic rays obtained from Webber et al., Seo et al., Menn et al., Ryan et al. and experiments like JACEE, CRN, SOKOL, RICH on P, He, CNO, Ne-S and Fe have been considered to estimate the vertical sea level muon energy spectra. The primary elemental energy spectra of P, He, CNO, Ne-S and Fe available from the different experimental data duly fitted by power law are given by Np(E)dE = 1.2216E-2.68 dE [cm2 .s.sr.GeV/n]-1 NHe(E)dE = 0.0424E-2.59 dE [cm2 .s.sr.GeV/n]-1 NCNO(E)dE = 0.0026E-2.57 dE[cm2 .s.sr.GeV/n]-1 NNe-S(E)dE = 0.00066E-2.57 dE [cm2 .s.sr.GeV/n]-1 NF e(E)dE = 0.0056E-2.55 dE [cm2 .s.sr.GeV/n]-1 Using the conventional superposition model the all nucleon primary cosmic ray spectrum has been derived which is of the form N(E)dE = 1.42E-2.66 dE [cm2 .s.sr.GeV/n]-1 We have considered all these spectra separately as parents of the secondary mesons and finallty the sea level muon fluxes at 00 from each species have been derived. To evaluate the meson spectra which are the initial air shower interaction products initiated by the primary nucleon air collisions, the hadronic energy moments have been calculated from the CERN LEBCEHS data for pp collisions and FNAL data for ?p collisions. Pion production by secondary pions have been taken into account and the final total muon spectrum has been derived from pp rightarrow?± x, pp ? K± x, ?p ? ?± x channels. The Z-factors have been corrected for p-air collisions. We have adopted the constant values of ?p-air and ??-air crosssections which are 273 mb and 213 mb, respectively. The adopted inelastic cross-sections for pp and ?p interactions are 35 mb and 22 mb, respectively. The Q-G plasma correction of Z-factors have also been incorporated in the final form. The solution to the standard differential equation for mesons is considered for muon flux estimation from Ngenerations of the parent mesons. By this formulation vertical muon spectra from each element along with the total primary nucleon spectrum have been derived. We wanted to observe the different shape of the muon spectra evaluated from different elemental spectra and to make a comparative study of that. In this energy range (102 - 104 ) GeV we have observed that the majority of the total muon flux is coming from the proton spectra. The contribution from the other elemental spectra to the total muon flux is not at all comparable with that of proton spectra.

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

453

Supernova spectra below strong circumstellar interaction  

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

454

New LRS spectra for 356 bright IRAS sources  

NASA Technical Reports Server (NTRS)

The low-resolution spectra of all IRAS point sources with F(nu) (12 microns) greater than 40 Jy that were not included in the Atlas of Low-Resolution Spectra are presented. These have been classified into eight groups based upon the spectral morphology. Silicate emission spectra and red-continuum spectra associated with H II region sources form about 60 percent of this sample. All types of spectra in the LRS Atlas are represented in the sample except for emission-line sources. The sample is used to test a recent classification scheme for IRAS sources based on broadband colors. The spectra is used to test a recent classification scheme for IRAS sources based on broadband colors. The spectra are consistent with the classifications from the colors in most cases.

Volk, Kevin; Cohen, Martin

1989-01-01

455

WebSpectra: Problems in NMR and IR Spectroscopy  

NSDL National Science Digital Library

From the University of California at Los Angeles's Chemistry Department, WebSpectra provides chemistry students with a searchable library of Nuclear Magnetic Resonance (NMR) and Infrared (IR) spectroscopy problems. According to the makers of this innovative site, "Interpretation of spectra is a technique that requires practice - this site provides 1H NMR and 13C NMR, DEPT, COSY and IR spectra of various compounds for students to interpret." A set of instructional documents are entitled Solving Spectral Problems, Overview of NMR Spectroscopy, Notes on NMR Solvents, Types of NMR Spectra, Introduction to IR Spectra, and a Table of IR Absorptions. A wide variety of compounds and their spectra are available for interpretation and have been organized in categories from Beginning to Advanced. Spectrum for each compound may be magnified 16X by clicking on peaks. This is an outstanding learning tool for students coming to grips with interpreting NMR and IR spectra.

456

IR SPECTRA BY DFT FOR GLUCOSE AND ITS EPIMERS: A COMPARISON BETWEEN VACUUM AND SOLVATED SPECTRA  

Technology Transfer Automated Retrieval System (TEKTRAN)

Infrared spectra were calculated for the low energy geometry optimized structures of glucose and all of its epimers, at B3LYP/6-311++G** level of theory. Calculations were performed both in vacuo and using the COSMO solvation method. Frequencies, zero point energies, enthalpies, entropies, and rel...

457

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

NASA Astrophysics Data System (ADS)

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.

Hu, Shao Ming; Gao, Dong Yang

2014-11-01

458

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

PubMed

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

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

2013-05-01

459

Mineral Spectra from Nili Fossae, Mars  

NASA Technical Reports Server (NTRS)

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

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

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

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

2008-01-01

460

Spectra of functionalized operators arising from hypersurfaces  

NASA Astrophysics Data System (ADS)

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.

Hayrapetyan, Gurgen; Promislow, Keith

2014-08-01

461

Far infrared spectra of nonlinear optical crystals  

NASA Astrophysics Data System (ADS)

Far-infrared (FIR) transmission spectra have been measured for several nonlinear crystals. The results show that both GaP and ZnGeP2 have a fairly narrow Restrahlen band. After the Mid-infrared (MIR) cut off at wavelengths near 12 micrometers, the crystals begin transmitting again at wavelengths of 100 micrometers. The transmissivity is highly dependent on the conductivity of the samples as free carrier absorption will deleteriously affect transmission. These results indicate that these crystals may be used for generation of FIR radiation using difference frequency generation (DFG) from the Near-Infrared (NIR) or MIR. High resistivity GaAs and GaSe should have similar properties, but no high resistivity material was found. Other crystals such as LiNbO3, LiIO3, BBO and KTP may be used at longer wavelengths.

Herman, Gregory S.; Bertelli, Gianluigi

1995-04-01

462

Workshop to establish databases of carbohydrate spectra  

SciTech Connect

The workshop was organized to formulate guidelines for establishing spectral databases of complex carbohydrates. The databases will enable the scientific community to avoid the great waste of research effort and funds that frequently occurs when carbohydrate chemists are forced to duplicate the structural characterization of previously characterized complex carbohydrates. Chemists waste their effort on repetitive characterizations because in the absence of spectral databases they are unaware they are analyzing a known molecule until they have completely determined its structure. Chemists will be able to avoid much of this wasted effort when the collections of mass and of nuclear magnetic resonance (NMR) spectra initiated at the workshop are subsequently developed into searchable databases. Then scientists only need query the databases with the spectrum or with information defining the spectrum of an unidentified carbohydrate to find out if it has been previously characterized.

NONE

1995-12-31

463

Electron spectra from decay of fission products  

SciTech Connect

Electron spectra following decay of individual fission products (72 less than or equal to A less than or equal to 162) are obtained from the nuclear data given in the compilation using a listed and documented computer subroutine. Data are given for more than 500 radionuclides created during or after fission. The data include transition energies, absolute intensities, and shape parameters when known. An average beta-ray energy is given for fission products lacking experimental information on transition energies and intensities. For fission products having partial or incomplete decay information, the available data are utilized to provide best estimates of otherwise unknown decay schemes. This compilation is completely referenced and includes data available in the reviewed literature up to January 1982.

Dickens, J K

1982-09-01

464

Oxidation of carbynes: Signatures in infrared spectra  

SciTech Connect

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.

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

465

Spectra as windows into exoplanet atmospheres.  

PubMed

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

Burrows, Adam S

2014-09-01

466

Vibrational spectra and DFT calculations of squalene  

NASA Astrophysics Data System (ADS)

The isoprenoid compound squalene is a building block molecule for the production of essential cellular molecules such as membrane sterols, has several therapeutic activities including anticancer properties, and has commercial applications for a variety of industries including the production of cosmetics. While the physical structure of squalene has been known for many years, a spectroscopic understanding of the squalene molecular structure and how these spectrometric properties relate to the physical squalene structure has yet to be reported. In the present work we present the Raman and infrared spectra of liquid squalene, complemented by DFT calculations. The molecule has 234 vibrational frequencies and these have been categorized according to the different types of vibrational modes present. The vibrational modes are highly mixed and these have been assigned for the more prominent infrared and Raman bands.

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

2013-01-01

467

[Spectra classification based on generalized discriminant analysis].  

PubMed

A kernel based generalized discriminant analysis (GDA) technique is proposed for the classification of stars, galaxies, and quasars. GDA combines the LDA algorithm with kernel trick, and samples are projected by nonlinear mapping onto the feature space F with high dimensions, and then LDA is conducted in F. Also, it could be inferred that GDA which combines the extension of Fisher's criterion with kernel trick is complementary to kernel Fisher discriminant framework. LDA, GDA, PCA and KPCA were experimentally compared with these three different kinds of spectra. Among these four techniques, GDA obtains the best result, followed by LDA, and PCA is the worst. Although KPCA is also a kernel based technique, its performance is not satisfactory if the selected number of the principal components is small, and in some cases, it appears even worse than LDA, a non-kernel based technique. PMID:17205763

Xu, Xin; Yang, Jin-fu; Wu, Fu-chao; Zhao, Yong-heng

2006-10-01

468

Measuring Reddening with SDSS Stellar Spectra  

NASA Astrophysics Data System (ADS)

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

Schlafly, Eddie; Finkbeiner, D. P.

2011-01-01

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IR spectra of irradiated organic materials  

NASA Astrophysics Data System (ADS)

Infrared spectra of organic molecules, including frozen gases, aliphatic and aromatic polymers, complex molecules, and biological compounds are presented, and their changes due to fast ion bombardment are described. It is found that (1) the targets lose hydrogen preferentially and the stoichiometric H/C decreases; (2) the materials become more absorbing and their color changes from white to black as the ion dose increases; (3) the crystallinity, if present initially, is destroyed, and bombarded material is amorphous although microcrystallinity cannot be ruled out; (4) the skeletal vibrations are changed, indicating the occurrence of cross-lining and the formation of tridimensional networks. The astrophysical and space mission implications of these findings are addressed.

Strazzulla, G.; Calcagno, L.; Foti, A. M.; Massimino, P.; Spinella, F.

1988-05-01