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Sample records for comparative structural spectral

  1. [Comparative Study on the Molecular Structures and Spectral Properties of Ponceau 4R and Amaranth].

    PubMed

    Zhang, Yong; Chen, Guo-qing; Zhu, Chun; Hu, Yang-jun

    2015-11-01

    The Edinburgh FLS920P steady-instantaneous fluorescence spectrometer was applied on the detection of the absorption and the emission spectra of ponceau 4R and amaranth, which are isomers to each other. After that, the spectral parameters of them were compared. Then, the density functional theory (DFT) and time-dependent density functional theory (TD-DFT) were used on the optimization of ponceau 4R and amaranth under the ground and excited state, respectively, in order to compare the differences in configurations of them under different states. On the base of the results above, the absorption and emission spectra of the two isomers were calculated with TD-DFT, and the polarized continuum model (PCM) was applied on the base of 6-311++G (d, p). The fluorescence mechanism, the relationships between the properties of fluorescence spectra and the molecular geometry were all analyzed. The results shows that, the structures of the two molecules are non-planar, these two naphthalene rings are not co-planar, respectively, and there's hydrogen bond in amaranth. When the two isomers were on the ground state, the planarity of the naphthalene ring which exists the hydrogen bond mentioned above in amaranth is better than the corresponding part of ponceau 4R. The two isomers are nearly co-planar when they're on the excited state. The molecular structures of ponceau 4R and amaranth optimized above are basically reasonable, for the quantum chemistry calculation spectral results are agree with the experiments. The planarity of the naphthalene rings on the right side in ponceau 4R is worse than that in amaranth, the ponceau 4R molecule experienced more vibration and rotation from the excited to the ground state, lost more energy, which lead to the reduction of energy for emitting fluorescent photons. So ponceau 4R has longer fluorescence emission wave- length than amaranth. In this paper, the molecular structure information of ponceau 4R and amaranth were obtained, and the differences

  2. Planar-waveguide integrated spectral comparator.

    PubMed

    Mossberg, T W; Iazikov, D; Greiner, C

    2004-06-01

    A cost-effective yet robust and versatile dual-channel spectral comparator is presented. The silica-on-silicon planar-waveguide integrated device includes two holographic Bragg-grating reflectors (HBRs) with complementary spectral transfer functions. Output comprises projections of input signal spectra onto the complementary spectral channels. Spectral comparators may be useful in optical code-division multiplexing, optical packet decoding, spectral target recognition, and the identification of molecular spectra. HBRs may be considered to be mode-specific photonic crystals.

  3. Optic nerve head topography and retinal structural changes in eyes with macrodisks: a comparative study with spectral domain optical coherence tomography

    PubMed Central

    Öztürker, Zeynep Kayaarası; Eltutar, Kadir; Karini, Belma; Erkul, Sezin Özdogan; Osmanbaşoğlu, Özen Ayrancı; Sultan, Pınar

    2016-01-01

    Purpose To compare optic nerve head parameters, the thicknesses of the peripapillary retinal nerve fiber layer (pRNFL), the macular retinal nerve fiber layer (mRNFL), the ganglion cell complex (GCC), and the ganglion cell–inner plexiform layer (GCIPL) in macrodisks and normal-sized healthy disks using spectral domain optical coherence tomography. Patients and methods A total of 88 healthy eyes (42 macrodisks and 46 normal-sized disks) were prospectively enrolled in the study. Optic nerve head parameters as well as pRNFL, mRNFL, GCC, and GCIPL thicknesses were measured in all subjects. Optic disk areas (ODAs) >2.70 mm2 were defined as macrodisks. All spectral domain optical coherence tomography parameters were compared between normal-sized disks and macrodisks. Results The mean age of the participants was 49.4±5.7 years in the normal size group and 51.55±6.3 years in the macrodisk group (P=0.65). The average ODAs were 2.23±0.29 mm2 and 3.30±0.59 mm2 in the normal size and the macrodisk groups, respectively. ODA (P<0.001), cup area (P<0.001), cup disk area ratio (P<0.001), horizontal cup disk ratio (P<0.001), vertical cup disk ratio (P<0.001), horizontal disk diameter (P<0.001), vertical disk diameter (P<0.001), and cup volume (P<0.001) were significantly higher in the macrodisk group. The inferior mRNFL thickness was significantly lower (P=0.042), and the GCC inferior and GCIPL inferior thicknesses were found to be lower with low significance (P=0.052, P=0.059, respectively) in the macrodisk group. Rim volume (P=0.622), total pRNFL (P=0.201), superior pRNFL (P=0.123), inferior pRNFL (P=0.168), average macular thickness (P=0.162), total mRNFL (P=0.171), superior mRNFL (P=0.356), total GCC (P=0.080), superior GCC (P=0.261), total GCIPL (P=0.214), and superior GCIPL (P=0.515) thicknesses were similar in both groups. Conclusion Optic disk topography and retinal structures show different characteristics in healthy eyes with macrodisks. These disk size

  4. Synthesis of Y3Al5O12:Tb & Y3Al5O12:Tb,Si phosphor by combustion synthesis: Comparative investigations on the structural and spectral properties

    NASA Astrophysics Data System (ADS)

    Upasani, Manisha

    2017-02-01

    YAG:Tb polycrystalline powders have been prepared by combustion synthesis at low temperature. Structure and morphology of the obtained materials have been studied. Various structural parameters have been determined by X-ray powder diffraction measurements. Effect of Si codoping on structural and spectral properties have been compared. It has been shown that critical amount of Si found suitable for pure phase formation and enhancement in Tb3+ characteristics green emission in YAG.

  5. Multilayer structure for a spectral imaging sensor.

    PubMed

    Parrein, Pascale; Moussy, Norbert; Poupinet, Ludovic; Gidon, Pierre

    2009-01-20

    We investigate the possibility of recovering spectral information using a multilayer structure realized through microelectronics technologies and compatible with a matrix arrangement. The structure is made of photoabsorbing layers, acting as local photodetectors, alternating with transparent layers. The whole structure lies on a reflective surface. A stationary wave containing the spectral information of the source is generated within the structure. We determine the intensity of the stationary wave at any position, taking into account absorption and multireflections at each transition as well as the signal detected by the photoabsorbing layers. The model forecasting the detected signal is then validated using p-i-n diodes of different thicknesses made of hydrogenated amorphous silicon (a-Si:H) encompassed between indium tin oxide (ITO) electrodes. The detected signal depends on the wavelength of the incident light, the thickness of the detecting layer, and the latter's position within the structure. A specific spectral response can then be associated to each photoabsorbing layer. We show how spectral information can be retrieved from this kind of structure in the visible spectrum range.

  6. Thematic Mapper Spectral Dimensionality and Data Structure

    NASA Technical Reports Server (NTRS)

    Crist, E. P.; Cicone, R. C.

    1985-01-01

    A simulated LANDSAT 4 TM and MSS data set, representing three crops over three growing seasons and a wide variety of soil types, was used to evaluate the structure of TM data and to compare its characteristics to those of MSS data. TM bands 2, 3, and 4, transformed to tasseled cap-like coordinates, provide an equivalent data space to MSS tasseled cap data, with greater dynamic range and no apparent loss of information resulting from the exclusion of the 0.9 to 1.1 micron region. Data from the six reflective TM bands (excluding the thermal band) primarily occupy two planes and a transition zone between them. The plane of vegetation is comparable to the MSS tasseled cap plane, while the plane of soils and transition zone provide a new dimension of information unavailable from the MSS. This added dimension offers promise of improved ability to determine the relative mix of vegetation and soil in the sensor field of view and to estimate soil moisture status. The improvement in spectral characteristics of the TM over the MSS, not to mention the greater spatial resolution, have resulted in a significant increase in the information content of the data.

  7. Comparative noise performance of a coded aperture spectral imager

    NASA Astrophysics Data System (ADS)

    Piper, Jonathan; Yuen, Peter; Godfree, Peter; Ding, Mengjia; Soori, Umair; Selvagumar, Senthurran; James, David

    2016-10-01

    Novel types of spectral sensors using coded apertures may offer various advantages over conventional designs, especially the possibility of compressive measurements that could exceed the expected spatial, temporal or spectral resolution of the system. However, the nature of the measurement process imposes certain limitations, especially on the noise performance of the sensor. This paper considers a particular type of coded-aperture spectral imager and uses analytical and numerical modelling to compare its expected noise performance with conventional hyperspectral sensors. It is shown that conventional sensors may have an advantage in conditions where signal levels are high, such as bright light or slow scanning, but that coded-aperture sensors may be advantageous in low-signal conditions.

  8. A comparative analysis of GPU implementations of spectral unmixing algorithms

    NASA Astrophysics Data System (ADS)

    Sanchez, Sergio; Plaza, Antonio

    2011-11-01

    Spectral unmixing is a very important task for remotely sensed hyperspectral data exploitation. It involves the separation of a mixed pixel spectrum into its pure component spectra (called endmembers) and the estimation of the proportion (abundance) of each endmember in the pixel. Over the last years, several algorithms have been proposed for: i) automatic extraction of endmembers, and ii) estimation of the abundance of endmembers in each pixel of the hyperspectral image. The latter step usually imposes two constraints in abundance estimation: the non-negativity constraint (meaning that the estimated abundances cannot be negative) and the sum-toone constraint (meaning that the sum of endmember fractional abundances for a given pixel must be unity). These two steps comprise a hyperspectral unmixing chain, which can be very time-consuming (particularly for high-dimensional hyperspectral images). Parallel computing architectures have offered an attractive solution for fast unmixing of hyperspectral data sets, but these systems are expensive and difficult to adapt to on-board data processing scenarios, in which low-weight and low-power integrated components are essential to reduce mission payload and obtain analysis results in (near) real-time. In this paper, we perform an inter-comparison of parallel algorithms for automatic extraction of pure spectral signatures or endmembers and for estimation of the abundance of endmembers in each pixel of the scene. The compared techniques are implemented in graphics processing units (GPUs). These hardware accelerators can bridge the gap towards on-board processing of this kind of data. The considered algorithms comprise the orthogonal subspace projection (OSP), iterative error analysis (IEA) and N-FINDR algorithms for endmember extraction, as well as unconstrained, partially constrained and fully constrained abundance estimation. The considered implementations are inter-compared using different GPU architectures and hyperspectral

  9. Passive Microwave Spectral Imaging of Amospheric Structure

    NASA Technical Reports Server (NTRS)

    Staelin, David H.; Rosenkranz, Philip W.

    1998-01-01

    The primary objective of this research was to improve the scientific foundation necessary to full realization of the meteorological potential of the NOAA Advanced Microwave Sounding Unit (AMSU) recently first launched on the NOAA-15 satellite in May, 1998. These advances were made in four main areas: (1) improvements, based on aircraft observations, in the atmospheric transmittance expressions used for interpreting AMSU and similar data; (2) development of neural network retrieval methods for cloud top altitude estimates of approximately 1-km accuracy under cirrus shields--the altitude is that of the larger ice particles aloft, which is related to precipitation rate; (3) analysis of early AMSU flight data with respect to its precipitation sensitivity and fine-scale thermal structure; and (4) improvements to the 54-GHz and 118-GHz MTS aircraft imaging spectrometer now operating on the NASA ER-2 aircraft. More specifically, the oxygen transmittance expressions near 118 GHz were in better agreement with aircraft data when the temperature dependence exponent of the 118.75-GHz linewidth was increased from the MPM92 value (Liebe et al., 1992) of 0.8 to 0.97+/-0.03. In contrast, the observations 52.5-55.8 GHz were consistent with the MPM92 model. Neural networks trained on comparisons of 118-GHz spectral data and coincident stereoscopic video images of convective cells observed from 20-km altitude yielded agreement in their peak altitudes within as little as 1.36 km rms, much of which is stereoscopic error. Imagery using these methods produced useful characterizations for Cyclone Oliver in 1993 and other storms (Schwartz et al., 1996; Spina et al., 1998). Similar neural network techniques yielded simulated rms errors in relative humidity retrievals of 6-14 percent over ocean and 6-15 percent over land at pressure levels from 1013 to 131 mbar (Cabrera-Mercader and Staelin, 1995).

  10. Spectral entropy criteria for structural segmentation in genomic DNA sequences

    NASA Astrophysics Data System (ADS)

    Chechetkin, V. R.; Lobzin, V. V.

    2004-07-01

    The spectral entropy is calculated with Fourier structure factors and characterizes the level of structural ordering in a sequence of symbols. It may efficiently be applied to the assessment and reconstruction of the modular structure in genomic DNA sequences. We present the relevant spectral entropy criteria for the local and non-local structural segmentation in DNA sequences. The results are illustrated with the model examples and analysis of intervening exon-intron segments in the protein-coding regions.

  11. Thematic Mapper Spectral Dimensionality and Data Structure

    NASA Technical Reports Server (NTRS)

    Crist, E. P.; Cicone, R. C.

    1984-01-01

    Thematic Mapper data, simulated from field and laboratory spectrometer measurements of a variety of agricultural crops and a wide range of soils, are analyzed to determine their dispersion in the six space defined by the reflective TM bands (i.e., excluding the thermal band). While similar analyses of MSS data from agricultural scenes show that the vast majority of the MSS data occupy a single plane, the simulated TM data primarily occupy three dimensions, defining two intersecting planes and a zone of transition between the two. Viewing the plane of Vegetation head on provides a projection comparable to the single plane of MSS data. The Plane of Soils and transition zone represent new information made available largely as a result of the longer infrared bands included in the Thematic Mapper. A transformation, named the Thematic Mapper Tasseled Cap, is presented which rotates the TM data such that the described data structure is most readily accessible to view.

  12. Spectral structure and stability studies on microstructure-fiber continuum

    NASA Astrophysics Data System (ADS)

    Gu, Xun; Kimmel, Mark; Zeek, Erik; Shreenath, Aparna P.; Trebino, Rick P.; Windeler, Robert S.

    2003-07-01

    Although previous direct measurements of the microstructure-fiber continuum have all showed a smooth and stable spectrum, our cross-correlation frequency-resolved optical gating (XFROG) full-intensity-and-phase characterization of the continuum pulse, utilizing sum-frequency-generation with a pre-characterized reference pulse and the angle-dithered-crystal technique, indicates that fine-scale spectral structure exists on a single-shot basis, contrary to previous observations. In particular, deep and fine oscillations are found in the retrieved spectrum, and the retrieved trace contains a "measles" pattern, whereas the measured trace and the independently-measured spectrum are rather smooth. The discrepancy is shown to be the result of unstable single-shot spectral structure. Although the XFROG measurement is not able to directly measure the single-shot fine structure in the trace, the redundancy of information in FROG traces enables the retrieval algorithm to correctly recognize the existence of the spectral fine structure, and restore the structure in the retrieved trace and spectrum. Numerical simulations have supported our hypothesis, and we directly observed the fine spectral structure in single-shot measurements of the continuum spectrum and the structure was seen to be highly unstable, the continuum spectrum appearing smooth only when many shots are averaged. Despite the structure and instability in the continuum spectrum, coherence experiments also reveal that the spectral phase is rather stable, being able to produce well-defined spectral fringes across the entire continuum bandwidth.

  13. Tensor Spectral Clustering for Partitioning Higher-order Network Structures

    PubMed Central

    Benson, Austin R.; Gleich, David F.; Leskovec, Jure

    2016-01-01

    Spectral graph theory-based methods represent an important class of tools for studying the structure of networks. Spectral methods are based on a first-order Markov chain derived from a random walk on the graph and thus they cannot take advantage of important higher-order network substructures such as triangles, cycles, and feed-forward loops. Here we propose a Tensor Spectral Clustering (TSC) algorithm that allows for modeling higher-order network structures in a graph partitioning framework. Our TSC algorithm allows the user to specify which higher-order network structures (cycles, feed-forward loops, etc.) should be preserved by the network clustering. Higher-order network structures of interest are represented using a tensor, which we then partition by developing a multilinear spectral method. Our framework can be applied to discovering layered flows in networks as well as graph anomaly detection, which we illustrate on synthetic networks. In directed networks, a higher-order structure of particular interest is the directed 3-cycle, which captures feedback loops in networks. We demonstrate that our TSC algorithm produces large partitions that cut fewer directed 3-cycles than standard spectral clustering algorithms. PMID:27812399

  14. Tensor Spectral Clustering for Partitioning Higher-order Network Structures.

    PubMed

    Benson, Austin R; Gleich, David F; Leskovec, Jure

    2015-01-01

    Spectral graph theory-based methods represent an important class of tools for studying the structure of networks. Spectral methods are based on a first-order Markov chain derived from a random walk on the graph and thus they cannot take advantage of important higher-order network substructures such as triangles, cycles, and feed-forward loops. Here we propose a Tensor Spectral Clustering (TSC) algorithm that allows for modeling higher-order network structures in a graph partitioning framework. Our TSC algorithm allows the user to specify which higher-order network structures (cycles, feed-forward loops, etc.) should be preserved by the network clustering. Higher-order network structures of interest are represented using a tensor, which we then partition by developing a multilinear spectral method. Our framework can be applied to discovering layered flows in networks as well as graph anomaly detection, which we illustrate on synthetic networks. In directed networks, a higher-order structure of particular interest is the directed 3-cycle, which captures feedback loops in networks. We demonstrate that our TSC algorithm produces large partitions that cut fewer directed 3-cycles than standard spectral clustering algorithms.

  15. Ion spectral structures observed by the Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Ferradas, C.; Zhang, J.; Spence, H. E.; Kistler, L. M.; Larsen, B.; Reeves, G. D.; Skoug, R. M.; Funsten, H. O.

    2015-12-01

    During the last decades several missions have recorded the presence of dynamic spectral features of energetic ions in the inner magnetosphere. Previous studies have reported single "nose-like" structures occurring alone and simultaneous nose-like structures (up to three). These ion structures are named after the characteristic shapes of energy bands or gaps in the energy-time spectrograms of in situ measured ion fluxes. They constitute the observational signatures of ion acceleration, transport, and loss in the global magnetosphere. The HOPE mass spectrometer onboard the Van Allen Probes measures energetic hydrogen, helium, and oxygen ions near the inner edge of the plasma sheet, where these ion structures are observed. We present a statistical study of nose-like structures, using 2-years measurements from the HOPE instrument. The results provide important details about the spatial distribution (dependence on geocentric distance), spectral features of the structures (differences among species), and geomagnetic conditions under which these structures occur.

  16. Statistical shape analysis of subcortical structures using spectral matching.

    PubMed

    Shakeri, Mahsa; Lombaert, Herve; Datta, Alexandre N; Oser, Nadine; Létourneau-Guillon, Laurent; Lapointe, Laurence Vincent; Martin, Florence; Malfait, Domitille; Tucholka, Alan; Lippé, Sarah; Kadoury, Samuel

    2016-09-01

    Studying morphological changes of subcortical structures often predicate neurodevelopmental and neurodegenerative diseases, such as Alzheimer's disease and schizophrenia. Hence, methods for quantifying morphological variations in the brain anatomy, including groupwise shape analyses, are becoming increasingly important for studying neurological disorders. In this paper, a novel groupwise shape analysis approach is proposed to detect regional morphological alterations in subcortical structures between two study groups, e.g., healthy and pathological subjects. The proposed scheme extracts smoothed triangulated surface meshes from segmented binary maps, and establishes reliable point-to-point correspondences among the population of surfaces using a spectral matching method. Mean curvature features are incorporated in the matching process, in order to increase the accuracy of the established surface correspondence. The mean shapes are created as the geometric mean of all surfaces in each group, and a distance map between these shapes is used to characterize the morphological changes between the two study groups. The resulting distance map is further analyzed to check for statistically significant differences between two populations. The performance of the proposed framework is evaluated on two separate subcortical structures (hippocampus and putamen). Furthermore, the proposed methodology is validated in a clinical application for detecting abnormal subcortical shape variations in Alzheimer's disease. Experimental results show that the proposed method is comparable to state-of-the-art algorithms, has less computational cost, and is more sensitive to small morphological variations in patients with neuropathologies.

  17. The Spectral Signature of Cloud Spatial Structure in Shortwave Radiation

    NASA Astrophysics Data System (ADS)

    Song, Shi

    In this thesis, we aim to systematically understand the relationship between cloud spatial structure and its radiation imprints, i.e., three-dimensional (3D) cloud effects, with the ultimate goal of deriving accurate radiative energy budget estimates from space, aircraft, or ground-based observations under spatially inhomogeneous conditions. By studying the full spectral information in the measured and modeled shortwave radiation fields of heterogeneous cloud scenes sampled during aircraft field experiments, we find evidence that cloud spatial structure reveals itself through spectral signatures in the associated irradiance and radiance fields in the near-ultraviolet and visible spectral range. The spectral signature of 3D cloud effects in irradiances is apparent as a domain- wide, consistent correlation between the magnitude and spectral dependence of net horizontal photon transport. The physical mechanism of this phenomenon is molecular scattering in conjunction with cloud heterogeneity. A simple parameterization with a single parameter epsilon is developed, which holds for individual pixels and the domain as a whole. We then investigate the impact of scene parameters on the discovered correlation and find that it is upheld for a wide range of scene conditions, although the value of epsilon varies from scene to scene. The spectral signature of 3D cloud effects in radiances manifests itself as a distinct relationship between the magnitude and spectral dependence of reflectance, which cannot be reproduced in the one-dimensional (1D) radiative transfer framework. Using the spectral signature in radiances and irradiances, it is possible to infer information on net horizontal photon transport from spectral radiance perturbations on the basis of pixel populations in sub-domains of a cloud scene. We show that two different biases need to be considered when attempting radiative closure between measured and modeled irradiance fields below inhomogeneous cloud fields: the

  18. Terahertz time-gated spectral imaging for content extraction through layered structures

    PubMed Central

    Redo-Sanchez, Albert; Heshmat, Barmak; Aghasi, Alireza; Naqvi, Salman; Zhang, Mingjie; Romberg, Justin; Raskar, Ramesh

    2016-01-01

    Spatial resolution, spectral contrast and occlusion are three major bottlenecks for non-invasive inspection of complex samples with current imaging technologies. We exploit the sub-picosecond time resolution along with spectral resolution provided by terahertz time-domain spectroscopy to computationally extract occluding content from layers whose thicknesses are wavelength comparable. The method uses the statistics of the reflected terahertz electric field at subwavelength gaps to lock into each layer position and then uses a time-gated spectral kurtosis to tune to highest spectral contrast of the content on that specific layer. To demonstrate, occluding textual content was successfully extracted from a packed stack of paper pages down to nine pages without human supervision. The method provides over an order of magnitude enhancement in the signal contrast and can impact inspection of structural defects in wooden objects, plastic components, composites, drugs and especially cultural artefacts with subwavelength or wavelength comparable layers. PMID:27610926

  19. Terahertz time-gated spectral imaging for content extraction through layered structures

    NASA Astrophysics Data System (ADS)

    Redo-Sanchez, Albert; Heshmat, Barmak; Aghasi, Alireza; Naqvi, Salman; Zhang, Mingjie; Romberg, Justin; Raskar, Ramesh

    2016-09-01

    Spatial resolution, spectral contrast and occlusion are three major bottlenecks for non-invasive inspection of complex samples with current imaging technologies. We exploit the sub-picosecond time resolution along with spectral resolution provided by terahertz time-domain spectroscopy to computationally extract occluding content from layers whose thicknesses are wavelength comparable. The method uses the statistics of the reflected terahertz electric field at subwavelength gaps to lock into each layer position and then uses a time-gated spectral kurtosis to tune to highest spectral contrast of the content on that specific layer. To demonstrate, occluding textual content was successfully extracted from a packed stack of paper pages down to nine pages without human supervision. The method provides over an order of magnitude enhancement in the signal contrast and can impact inspection of structural defects in wooden objects, plastic components, composites, drugs and especially cultural artefacts with subwavelength or wavelength comparable layers.

  20. Structure and spectral-luminescent properties of polymethine dyes

    NASA Astrophysics Data System (ADS)

    Ishchenko, Aleksandr A.

    1991-08-01

    The review considers the influence of the length of the polymethine chain, the structures of the hetero-radicals, the nature of substituents, electronic asymmetry, interactions of chromophores, structures of ion-pairs, photochemical reactions with proton transfer, and concentration, on the spectral-luminescent properties of polymethine dyes. The characteristic features of these properties in low-polarity media, including polymeric matrices, are discussed. Solvatochromism and solvatofluorochromism of polymethines are considered. Major factors influencing changes in the spectral-luminescent properties of cyanines, in relation to their structure and the nature of the medium, are revealed. Possible applications of polymethines to the solution of various problems connected with the transformation of light energy are discussed. The bibliography includes 231 references.

  1. Fiber Bragg grating spectral features for structural health monitoring of composite structures

    NASA Astrophysics Data System (ADS)

    Webb, Sean; Peters, Kara; Zikry, Mohammed; Stan, Nikola; Chadderdon, Spencer; Selfridge, Richard; Schultz, Stephen

    2014-05-01

    We demonstrate the measurement of and applications for reflected spectral signatures obtained from FBG sen- sors in dynamic environments. Three uses of the spectral distortion measurements for monitoring of airframe structures are presented: the measurement of the dynamic response of a laminated plate to an impact event; the measurement of damage induced spectral distortion in a thin plate during vibration loading; and the measurement of the change in dynamic response of an adhesively bonded joint with the progression of fatigue damage.

  2. Morphological, structural, and spectral characteristics of amorphous iron sulfates

    NASA Astrophysics Data System (ADS)

    Sklute, E. C.; Jensen, H. B.; Rogers, A. D.; Reeder, R. J.

    2015-04-01

    Current or past brine hydrologic activity on Mars may provide suitable conditions for the formation of amorphous ferric sulfates. Once formed, these phases would likely be stable under current Martian conditions, particularly at low- to mid-latitudes. Therefore, we consider amorphous iron sulfates (AIS) as possible components of Martian surface materials. Laboratory AIS were created through multiple synthesis routes and characterized with total X-ray scattering, thermogravimetric analysis, scanning electron microscopy, visible/near-infrared (VNIR), thermal infrared (TIR), and Mössbauer techniques. We synthesized amorphous ferric sulfates (Fe(III)2(SO4)3 · ~ 6-8H2O) from sulfate-saturated fluids via vacuum dehydration or exposure to low relative humidity (<11%). Amorphous ferrous sulfate (Fe(II)SO4 · ~ 1H2O) was synthesized via vacuum dehydration of melanterite. All AIS lack structural order beyond 11 Å. The short-range (<5 Å) structural characteristics of amorphous ferric sulfates resemble all crystalline reference compounds; structural characteristics for the amorphous ferrous sulfate are similar to but distinct from both rozenite and szomolnokite. VNIR and TIR spectral data for all AIS display broad, muted features consistent with structural disorder and are spectrally distinct from all crystalline sulfates considered for comparison. Mössbauer spectra are also distinct from crystalline phase spectra available for comparison. AIS should be distinguishable from crystalline sulfates based on the position of their Fe-related absorptions in the visible range and their spectral characteristics in the TIR. In the NIR, bands associated with hydration at ~1.4 and 1.9 µm are significantly broadened, which greatly reduces their detectability in soil mixtures. AIS may contribute to the amorphous fraction of soils measured by the Curiosity rover.

  3. Wake fields in 9-cell TESLA accelerating structures : Spectral Element Discontinuous Galerkin (SEDG) simulations.

    SciTech Connect

    Min, M.; Fischer, P. F.; Chae, Y.-C.

    2007-01-01

    Using our recently developed high-order accurate Maxwell solver, NEKCEM, we carried out longitudinal wakefield calculations for a 9-cell TESLA cavity structure in 3D. Indirect method is used for wake potential calculations. Computational results with NEKCEM are compared with those of GdfidL. NEKCEM uses a spectral element discontinuous Galerkin (SEDG) method based on a domain decomposition approach using spectral-element discretizations on Gauss-Lobatto-Legendre grids with body-conforming hexahedral meshes. The numerical scheme is designed to ensure high-order spectral accuracy, using the discontinuous Galerkin form with boundary conditions weakly enforced through a flux term between elements. Concerns related to implementation on wake potential calculations are discussed, and wake potential calculations with indirect method by NEKCEM compared with the results of the finite difference time-domain code GdfidL.

  4. Spectral structure and decompositions of optical states, and their applications

    NASA Astrophysics Data System (ADS)

    Rohde, Peter P.; Mauerer, Wolfgang; Silberhorn, Christine

    2007-04-01

    We discuss the spectral structure and decomposition of multi-photon states. Ordinarily 'multi-photon states' and 'Fock states' are regarded as synonymous. However, when the spectral degrees of freedom are included this is not the case, and the class of 'multi-photon' states is much broader than the class of 'Fock' states. We discuss the criteria for a state to be considered a Fock state. We then address the decomposition of general multi-photon states into bases of orthogonal eigenmodes, building on existing multi-mode theory, and introduce an occupation number representation that provides an elegant description of such states. This representation allows us to work in bases imposed by experimental constraints, simplifying calculations in many situations. Finally we apply this technique to several example situations, which are highly relevant for state of the art experiments. These include Hong Ou Mandel interference, spectral filtering, finite bandwidth photo-detection, homodyne detection and the conditional preparation of Schrödinger kitten and Fock states. Our techniques allow for very simple descriptions of each of these examples.

  5. Refining comparative proteomics by spectral counting to account for shared peptides and multiple search engines.

    PubMed

    Chen, Yao-Yi; Dasari, Surendra; Ma, Ze-Qiang; Vega-Montoto, Lorenzo J; Li, Ming; Tabb, David L

    2012-09-01

    Spectral counting has become a widely used approach for measuring and comparing protein abundance in label-free shotgun proteomics. However, when analyzing complex samples, the ambiguity of matching between peptides and proteins greatly affects the assessment of peptide and protein inventories, differentiation, and quantification. Meanwhile, the configuration of database searching algorithms that assign peptides to MS/MS spectra may produce different results in comparative proteomic analysis. Here, we present three strategies to improve comparative proteomics through spectral counting. We show that comparing spectral counts for peptide groups rather than for protein groups forestalls problems introduced by shared peptides. We demonstrate the advantage and flexibility of this new method in two datasets. We present four models to combine four popular search engines that lead to significant gains in spectral counting differentiation. Among these models, we demonstrate a powerful vote counting model that scales well for multiple search engines. We also show that semi-tryptic searching outperforms tryptic searching for comparative proteomics. Overall, these techniques considerably improve protein differentiation on the basis of spectral count tables.

  6. Refining comparative proteomics by spectral counting to account for shared peptides and multiple search engines

    PubMed Central

    Chen, Yao-Yi; Dasari, Surendra; Ma, Ze-Qiang; Vega-Montoto, Lorenzo J.; Li, Ming

    2013-01-01

    Spectral counting has become a widely used approach for measuring and comparing protein abundance in label-free shotgun proteomics. However, when analyzing complex samples, the ambiguity of matching between peptides and proteins greatly affects the assessment of peptide and protein inventories, differentiation, and quantification. Meanwhile, the configuration of database searching algorithms that assign peptides to MS/MS spectra may produce different results in comparative proteomic analysis. Here, we present three strategies to improve comparative proteomics through spectral counting. We show that comparing spectral counts for peptide groups rather than for protein groups forestalls problems introduced by shared peptides. We demonstrate the advantage and flexibility of this new method in two datasets. We present four models to combine four popular search engines that lead to significant gains in spectral counting differentiation. Among these models, we demonstrate a powerful vote counting model that scales well for multiple search engines. We also show that semi-tryptic searching outperforms tryptic searching for comparative proteomics. Overall, these techniques considerably improve protein differentiation on the basis of spectral count tables. PMID:22552787

  7. Urban, Forest, and Agricultural AIS Data: Fine Spectral Structure

    NASA Technical Reports Server (NTRS)

    Vanderbilt, V. C.

    1985-01-01

    Spectra acquired by the Airborne Imaging Spectrometer (AIS) near Lafayette, IN, Ely, MN, and over the Stanford University campus, CA were analyzed for fine spectral structure using two techniques: the ratio of radiance of a ground target to the radiance of a standard and also the correlation coefficient of radiances at adjacent wavelengths. The results show ramp like features in the ratios. These features are due to the biochemical composition of the leaf and to the optical scattering properties of its cuticle. The size and shape of the ramps vary with ground cover.

  8. [Comparative investigation of locust's phototactic visual spectrum effect and phototactic response to spectral illumination].

    PubMed

    Liu, Qi-Hang; Zhou, Qiang

    2014-07-01

    To provide theoretical support for determining locust's phototactic spectrum, and explore locust's phototactic mechanism stimulated by light, utilizing AvaSpec fiber-optic spectrometer system and AvaLight-DHS, the investigation of locust's phototactic visual spectrum effect after light energy stimulated locust's vision system was carried out and on this basis, utilizing the investigated device of locust's phototactic response to spectral illumination, the discrepancy of locust's phototactic response to spectral illumination was certificated comparatively. The results show that the degree of locust's vision system absorbing the single spectrum photon of 430, 545 and 610 nm is significant and there exists difference, and the behavioral response to orange, violet, green, and blue spectral light has the difference in selective sensitivity, with the intensity of response to violet light being the strongest. The degree of response to orange light is the maximum, simultaneously, locust's vision system absorbing spectral photon energy has selective difference and requirement of illumination time, moreover, the sensitive degree of locust's visual system to spectrum and the strength of the lighting energy, influencing locust's phototactic response degree, and the micro-response of locust's phototactic vision physiology, led by the photoelectric effect of locust absorbing sensitive photon and converting photon energy, is the reason for locust's phototactic orientation response. In addition, locust's phototactic visual spectrum effect, only when the biological photoelectric effect of locust's visual system is stimulated by spectral illumination, can present the sensitivity of the spectral absorption effect, so, using the stronger ultraviolet stimulation characteristic of violet light, the different sensitive stimulation of orange, green, blue spectral light on locust's phototactic vision, and combining orange, violet, green, blue spectral light field mechanism reasonably, can

  9. SOLAR RADIO BURSTS WITH SPECTRAL FINE STRUCTURES IN PREFLARES

    SciTech Connect

    Zhang, Yin; Tan, Baolin; Huang, Jing; Tan, Chengming; Karlický, Marian; Mészárosová, Hana; Simões, Paulo J.A.

    2015-01-20

    Good observations of preflare activities are important for us to understand the origin and triggering mechanism of solar flares, and to predict the occurrence of solar flares. This work presents the characteristics of microwave spectral fine structures as preflare activities of four solar flares observed by the Ondřejov radio spectrograph in the frequency range of 0.8-2.0 GHz. We found that these microwave bursts which occurred 1-4 minutes before the onset of flares have spectral fine structures with relatively weak intensities and very short timescales. They include microwave quasi-periodic pulsations with very short periods of 0.1-0.3 s and dot bursts with millisecond timescales and narrow frequency bandwidths. Accompanying these microwave bursts are filament motions, plasma ejection or loop brightening in the EUV imaging observations, and non-thermal hard X-ray emission enhancements observed by RHESSI. These facts may reveal certain independent, non-thermal energy releasing processes and particle acceleration before the onset of solar flares. They may help us to understand the nature of solar flares and to predict their occurrence.

  10. Zebra spectral structures in Jovian decametric radio emissions

    NASA Astrophysics Data System (ADS)

    Rošker, S.; Panchenko, M.; Rucker, H. O.; Brazhenko, A. I.

    2015-10-01

    Jupiter with the largest planetary magnetosphere in the solar system emits intense coherent non-thermal radiation in a wide frequency range. This emission is a result of complicated interactions between the dynamic Jovian magnetosphere and energetic particles supplying free energy from planetary rotation and the interaction between Jupiter and the Galilean moon Io. Decametric radio emission (DAM) is the strongest component of Jovian radiation observed in a frequency range from a few MHz up to 40 MHz. Depending on the time scales the Jovian DAM exhibits different complex spectral structures. Recent observations of the Jovian decametric radio emission using the large ground-based radio telescope URAN-2 (Poltava, Ukraine) enabled the detection of fine spectral structures, specifically zebra stripe-like patterns, never reported before in the Jovian decametric wavelength regime (Figure 1). In this presentation we describe and analyse these new observations by investigating the characteristics of the Jovian decametric zebra patterns. On basis of these findings the possible mechanism of wave generation is discussed and in particular the value of the determination of local plasma densities within the Jovian magnetosphere by remote radio sensing is emphasized.

  11. Dynamic spectral structure specifies vowels for children and adultsa

    PubMed Central

    Nittrouer, Susan

    2008-01-01

    When it comes to making decisions regarding vowel quality, adults seem to weight dynamic syllable structure more strongly than static structure, although disagreement exists over the nature of the most relevant kind of dynamic structure: spectral change intrinsic to the vowel or structure arising from movements between consonant and vowel constrictions. Results have been even less clear regarding the signal components children use in making vowel judgments. In this experiment, listeners of four different ages (adults, and 3-, 5-, and 7-year-old children) were asked to label stimuli that sounded either like steady-state vowels or like CVC syllables which sometimes had middle sections masked by coughs. Four vowel contrasts were used, crossed for type (front/back or closed/open) and consonant context (strongly or only slightly constraining of vowel tongue position). All listeners recognized vowel quality with high levels of accuracy in all conditions, but children were disproportionately hampered by strong coarticulatory effects when only steady-state formants were available. Results clarified past studies, showing that dynamic structure is critical to vowel perception for all aged listeners, but particularly for young children, and that it is the dynamic structure arising from vocal-tract movement between consonant and vowel constrictions that is most important. PMID:17902868

  12. Unfold Synchronization Community Structure Using Markov and Spectral Signature

    NASA Astrophysics Data System (ADS)

    Li, Ju; Chen, Diyi; Ma, Xiaoyi; Li, Huijia

    2012-12-01

    Synchronization is a powerful basic rule in nature that regulates a large variety of complex processes, and global synchronization phenomena have been extensively studied for modeling and analyzing the dynamic of systems. Distinct from the existing studies, the work presented here explores the notion of local synchronization phenomenon and their intrinsic properties from the dynamics of a stochastic model defined on a complex network. The relationship between the hierarchical community structure of the network and the local synchronization properties of such a stochastic model has been established based on the famous Kuramoto Model. Critical topological information regarding to the community structures of the network can be inferred from their spectral signatures. Utilizing a novel dynamic system, we have developed an efficient two stages model which can efficiently uncover natural communities hidden in networks in a scalable manner. The effectiveness and efficiency of the algorithm have been theoretically analyzed as well as experimentally validated and it overcomes the inefficiency of the existing methods.

  13. Approximating spectral impact of structural perturbations in large networks.

    PubMed

    Milanese, Attilio; Sun, Jie; Nishikawa, Takashi

    2010-04-01

    Determining the effect of structural perturbations on the eigenvalue spectra of networks is an important problem because the spectra characterize not only their topological structures, but also their dynamical behavior, such as synchronization and cascading processes on networks. Here we develop a theory for estimating the change of the largest eigenvalue of the adjacency matrix or the extreme eigenvalues of the graph Laplacian when small but arbitrary set of links are added or removed from the network. We demonstrate the effectiveness of our approximation schemes using both real and artificial networks, showing in particular that we can accurately obtain the spectral ranking of small subgraphs. We also propose a local iterative scheme which computes the relative ranking of a subgraph using only the connectivity information of its neighbors within a few links. Our results may not only contribute to our theoretical understanding of dynamical processes on networks, but also lead to practical applications in ranking subgraphs of real complex networks.

  14. Comparative study on the spectral properties of boron clusters Bn0/−1(n = 38–40)

    PubMed Central

    Li, Shixiong; Zhang, Zhengping; Long, Zhengwen; Sun, Guangyu; Qin, Shuijie

    2016-01-01

    The all-boron fullerenes B40−1 and B39−1 discovered in recent experiments are characterized and revealed using photoelectron spectroscopy. Except for the photoelectron spectroscopy, one may identify such boron clusters with other spectroscopic techniques, such as infrared spectra and Raman spectra. Insight into the spectral properties of boron clusters is important to understand the boron clusters and find their potential applications. In this work, density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations are carried out to comparatively study the vibrational frequencies, infrared spectra, Raman spectra and electronic absorption spectra of boron clusters Bn0/−1(n = 38–40). The numerical simulations show that such boron clusters have different and meaningful spectral features. These spectral features are readily compared with future spectroscopy measurements and can be used as fingerprints to distinguish the boron clusters Bn0/−1 with different structures (cage structure or quasi-planar structure) and with different sizes (n = 38–40). PMID:27113504

  15. Structural and Spectral Characteristics of Amorphous Iron Sulfates

    NASA Astrophysics Data System (ADS)

    Sklute, E.; Jensen, H. B.; Rogers, D.; Reeder, R. J.

    2014-12-01

    Substantial evidence points to the existence of hydrated sulfate phases on the Martian surface1-3. In addition, the discovery of recurring slope lineae could point to an active brine hydrologic cycle on the surface4,5. The rapid dehydration of both hydrated sulfates and sulfate-rich brines can lead to the formation of amorphous sulfates. Evidence suggests that the Rocknest soil target and the Sheepbed mudstone interrogated by the Mars Science Laboratory at Gale crater contain ~30 wt.% XRD amorphous material that is rich in both sulfur and iron6. These factors have led us to consider hydrated amorphous iron sulfates as possible components in Martian surface materials. Amorphous iron sulfates were created through multiple synthesis routes, and then characterized with total x-ray scattering, TGA, SEM, visible/near-infrared (VNIR), thermal infrared (TIR), and Mössbauer techniques. We synthesized amorphous ferric sulfates (Fe(III)2(SO4)3•~5-8H2O) from sulfate-saturated fluids via two pathways: vacuum dehydration and exposure to low relative humidity (<11%) using a LiCl buffer. Amorphous ferrous sulfate (Fe(II)SO4•~1H2O) was synthesized via vacuum dehydration of melanterite (Fe(II) SO4•7H2O). We find that both the ferric and ferrous sulfates synthesized from these methods lack long-range (>10Å) order, and thus are truly amorphous. VNIR and TIR spectral data for the amorphous sulfates display broad, muted features consistent with structural disorder and are spectrally distinct from all crystalline sulfates considered for comparison. Mössbauer spectra are also distinct from all crystalline phase spectra available for comparison. The amorphous sulfates should be distinguishable based on the position of their Fe-related absorptions in the visible range and their spectral characteristics in the TIR. In the NIR, which is the spectral range that has primarily been used to detect sulfates on Mars, the bands associated with hydration at ~1.4 and 1.9 μm are significantly

  16. Structural Documentation of Glycan Epitopes: Sequential Mass Spectrometry and Spectral Matching

    NASA Astrophysics Data System (ADS)

    Ashline, David J.; Hanneman, Andrew J. S.; Zhang, Hailong; Reinhold, Vernon N.

    2014-03-01

    Documenting mass spectral data is a fundamental aspect of accepted protocols. In this report, we contrast MSn sequential disassembly spectra obtained from natural and synthetic glycan epitopes. The epitopes considered are clusters found on conjugate termini of lipids and N- and O-glycans of proteins. The latter are most frequently pendant through a CID-labile HexNAc glycosidic linkage. The synthetic samples were supplied by collaborating colleagues and commercial sources and usually possessed a readily released reducing-end linker, a by-product of synthesis. All samples were comparably methylated, extracted, and MSn disassembled to compare their linkage and branching spectral details. Both sample types provide B-ion type fragments early in a disassembly pathway and their compositions are a suggestion of structure. Further steps of disassembly are necessary to confirm the details of linkage and branching. Included in this study were various Lewis and H antigens, 3- and 6-linked sialyl-lactosamine, NeuAc-2,8-NeuAc dimer, and Galα1,3Gal. Sample infusion provided high quality spectral data whereas disassembly to small fragments generates reproducible high signal/noise spectra for spectral matching. All samples were analyzed as sodium adducted positive ions. This study includes comparability statistics and evaluations on several mass spectrometers.

  17. Ion nose spectral structures observed by the Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Ferradas, C. P.; Zhang, J.-C.; Spence, H. E.; Kistler, L. M.; Larsen, B. A.; Reeves, G.; Skoug, R.; Funsten, H.

    2016-12-01

    We present a statistical study of nose-like structures observed in energetic hydrogen, helium, and oxygen ions near the inner edge of the plasma sheet. Nose structures are spectral features named after the characteristic shapes of energy bands or gaps in the energy-time spectrograms of in situ measured ion fluxes. Using 22 months of observations from the Helium Oxygen Proton Electron instrument onboard Van Allen Probe A, we determine the number of noses observed, and the minimum L shell reached and energy of each nose on each pass through the inner magnetosphere. We find that multiple noses occur more frequently in heavy ions than in H+ and are most often observed during quiet times. The heavy-ion noses penetrate to lower L shells than H+ noses, and there is an energy-magnetic local time (MLT) dependence in the nose locations and energies that is similar for all species. The observations are interpreted by using a steady state model of ion drift in the inner magnetosphere. The model is able to explain the energy and MLT dependence of the different types of nose structures. Different ion charge-exchange lifetimes are the main cause for the deeper penetration of heavy-ion noses. The species dependence and preferred geomagnetic conditions of multiple-nose events indicate that they must be on long drift paths, leading to strong charge-exchange effects. The results provide important insight into the spatial distribution, species dependence, and geomagnetic conditions under which nose structures occur.

  18. Spectral structure of X-shaped radio sources.

    NASA Astrophysics Data System (ADS)

    Lal, Dharam Vir; Rao, A. Pramesh

    2004-09-01

    Analysis of Giant Metrewave Radio Telescope low frequency data for an X-shaped source, 3C 223.1 has revealed an unusual result as discussed earlier by Lal & Rao (2004). The radio morphologies of it at 240 and 610 MHz show a well-denfied X-shaped structure with a pair of active jets along the north-south axis and a pair of wings along the east-west axis, that pass symmetrically through the undetected radio core. The wings (or low surface brightness jet) seem to have flatter spectral index with respect to the high surface brightness jet. This clearly shows the value of mapping the sample of X-shaped sources at low frequencies. Here we present our preliminary results for two more such sources.

  19. Comparing the diagnostic utility of sacroiliac spectral CT and MRI in axial spondyloarthritis

    PubMed Central

    Zhang, Ping; Yu, Kai Hu; Guo, Rui Min; Ran, Jun; Liu, Yao; Morelli, John; Runge, Val A

    2016-01-01

    Objective: To compare the clinical value of sacroiliac spectral CT and MRI in diagnosing axial spondyloarthritis (SpA). Methods: 137 patients with low back pain and suspected axial SpA were recruited. 76 patients were diagnosed with axial SpA, and 49 patients were diagnosed with non-specific low back pain (nLBP). Each patient underwent spectral CT and MRI examinations of the sacroiliac joints. Water- and calcium-based material decomposition images were reconstructed for quantitative analysis. The marrow-to-muscle ratios of water and calcium concentrations and short tau inversion recovery (STIR) signal intensity, as well as Hounsfield units in the ilium and sacrum were compared between nLBP and patients with axial SpA. Results: Spectral CT is comparable with MRI for the detection of bone marrow oedema, and it is superior to MRI for detection of osseous sclerosis and erosions. MRI is superior to spectral CT in detecting enthesitis and synovitis. There were statistically significant differences in STIR signal intensity, water concentration and calcium concentration ratios as well as CT values between nLBP and patients with axial SpA (p < 0.05) in the ilium. There was a statistically significant but weak correlation between ratios of water concentration and STIR signal intensity in both the ilium and sacrum (p < 0.05). Overall, the iliac water concentration was most sensitive for detection of patients with SpA. The positive likelihood ratio of the STIR signal intensity ratio was the highest. The diagnostic odds ratio of the calcium concentration ratio was the highest, and its negative likelihood ratio was the lowest. Conclusion: Spectral CT not only depicts findings of chronic sacroiliitis (i.e. bone erosion and sclerosis), but also can detect and quantify the extent of marrow oedema in patients with SpA with activity sacroiliitis. The sensitivity of MRI for diagnosis of early synovitis and enthesitis remains superior. The combination of spectral CT and MRI may

  20. Ion nose spectral structures observed by the Van Allen Probes

    DOE PAGES

    Ferradas, C. P.; Zhang, J. -C.; Spence, H. E.; ...

    2016-11-22

    Here, we present a statistical study of nose-like structures observed in energetic hydrogen, helium, and oxygen ions near the inner edge of the plasma sheet. Nose structures are spectral features named after the characteristic shapes of energy bands or gaps in the energy-time spectrograms of in situ measured ion fluxes. Using 22 months of observations from the Helium Oxygen Proton Electron (HOPE) instrument onboard Van Allen Probe A, we determine the number of noses observed, and the minimum L-shell reached and energy of each nose on each pass through the inner magnetosphere. We find that multiple noses occur more frequentlymore » in heavy ions than in H+, and are most often observed during quiet times. The heavy-ion noses penetrate to lower L shells than H+ noses and there is an energy-magnetic local time (MLT) dependence in the nose locations and energies that is similar for all species. The observations are interpreted using a steady-state model of ion drift in the inner magnetosphere. The model is able to explain the energy and MLT dependence of the different types of nose structures. Different ion charge exchange lifetimes are the main cause for the deeper penetration of heavy-ion noses. The species dependence and preferred geomagnetic conditions of multiple-nose events indicate that they must be on long drift paths, leading to strong charge-exchange effects. The results provide important insight into the spatial distribution, species dependence, and geomagnetic conditions under which nose structures occur.« less

  1. Ion nose spectral structures observed by the Van Allen Probes

    SciTech Connect

    Ferradas, C. P.; Zhang, J. -C.; Spence, H. E.; Kistler, L. M.; Larsen, Brian Arthur; Reeves, Geoffrey D.; Skoug, Ruth M.; Funsten, Herbert O.

    2016-11-22

    Here, we present a statistical study of nose-like structures observed in energetic hydrogen, helium, and oxygen ions near the inner edge of the plasma sheet. Nose structures are spectral features named after the characteristic shapes of energy bands or gaps in the energy-time spectrograms of in situ measured ion fluxes. Using 22 months of observations from the Helium Oxygen Proton Electron (HOPE) instrument onboard Van Allen Probe A, we determine the number of noses observed, and the minimum L-shell reached and energy of each nose on each pass through the inner magnetosphere. We find that multiple noses occur more frequently in heavy ions than in H+, and are most often observed during quiet times. The heavy-ion noses penetrate to lower L shells than H+ noses and there is an energy-magnetic local time (MLT) dependence in the nose locations and energies that is similar for all species. The observations are interpreted using a steady-state model of ion drift in the inner magnetosphere. The model is able to explain the energy and MLT dependence of the different types of nose structures. Different ion charge exchange lifetimes are the main cause for the deeper penetration of heavy-ion noses. The species dependence and preferred geomagnetic conditions of multiple-nose events indicate that they must be on long drift paths, leading to strong charge-exchange effects. The results provide important insight into the spatial distribution, species dependence, and geomagnetic conditions under which nose structures occur.

  2. Spectral analysis and structure preserving preconditioners for fractional diffusion equations

    NASA Astrophysics Data System (ADS)

    Donatelli, Marco; Mazza, Mariarosa; Serra-Capizzano, Stefano

    2016-02-01

    Fractional partial order diffusion equations are a generalization of classical partial differential equations, used to model anomalous diffusion phenomena. When using the implicit Euler formula and the shifted Grünwald formula, it has been shown that the related discretizations lead to a linear system whose coefficient matrix has a Toeplitz-like structure. In this paper we focus our attention on the case of variable diffusion coefficients. Under appropriate conditions, we show that the sequence of the coefficient matrices belongs to the Generalized Locally Toeplitz class and we compute the symbol describing its asymptotic eigenvalue/singular value distribution, as the matrix size diverges. We employ the spectral information for analyzing known methods of preconditioned Krylov and multigrid type, with both positive and negative results and with a look forward to the multidimensional setting. We also propose two new tridiagonal structure preserving preconditioners to solve the resulting linear system, with Krylov methods such as CGNR and GMRES. A number of numerical examples show that our proposal is more effective than recently used circulant preconditioners.

  3. Spectral methods and cluster structure in correlation-based networks

    NASA Astrophysics Data System (ADS)

    Heimo, Tapio; Tibély, Gergely; Saramäki, Jari; Kaski, Kimmo; Kertész, János

    2008-10-01

    We investigate how in complex systems the eigenpairs of the matrices derived from the correlations of multichannel observations reflect the cluster structure of the underlying networks. For this we use daily return data from the NYSE and focus specifically on the spectral properties of weight W=|-δ and diffusion matrices D=W/sj-δ, where C is the correlation matrix and si=∑jW the strength of node j. The eigenvalues (and corresponding eigenvectors) of the weight matrix are ranked in descending order. As in the earlier observations, the first eigenvector stands for a measure of the market correlations. Its components are, to first approximation, equal to the strengths of the nodes and there is a second order, roughly linear, correction. The high ranking eigenvectors, excluding the highest ranking one, are usually assigned to market sectors and industrial branches. Our study shows that both for weight and diffusion matrices the eigenpair analysis is not capable of easily deducing the cluster structure of the network without a priori knowledge. In addition we have studied the clustering of stocks using the asset graph approach with and without spectrum based noise filtering. It turns out that asset graphs are quite insensitive to noise and there is no sharp percolation transition as a function of the ratio of bonds included, thus no natural threshold value for that ratio seems to exist. We suggest that these observations can be of use for other correlation based networks as well.

  4. Structural investigations of human hairs by spectrally resolved ellipsometry

    NASA Astrophysics Data System (ADS)

    Chan, Danny; Schulz, Benjamin; Rübhausen, Michael; Wessel, Sonya; Wepf, Roger

    2006-01-01

    Human hair is a biological layered system composed of two major layers, the cortex and the cuticle. We show spectrally resolved ellipsometry measurements of the ellipsometric parameters Ψ and Δ of single human hairs. The spectra reflect the layered nature of hair and the optical anisotropy of the hair's structure. In addition, measurements on strands of human hair show a high reproducibility of the ellipsometric parameters for different hair fiber bundles from the same person. Based on the measurements, we describe a dielectric model of hair that explains the spectra in terms of the dielectric properties of the major parts of hair and their associated layer thicknesses. In addition, surface roughness effects modeled by a roughness layer with a complex refractive index given by an effective medium approach can be seen to have a significant effect on the measurements. We derive values for the parameters of the cuticle surface roughness layer of the thickness dACu=273 to 360 nm and the air inclusion fA=0.6 to 5.7%.

  5. Structural investigations of human hairs by spectrally resolved ellipsometry

    NASA Astrophysics Data System (ADS)

    Schulz, Benjamin; Chan, D.; Ruebhausen, M.; Wessel, S.; Wepf, R.

    2006-03-01

    Human hair is a biological layered system composed of two major layers, the cortex and the cuticle. We show spectrally resolved ellipsometry measurements of the ellipsometric parameters ψ and δ of single human hairs. The spectra reflect the layered nature of hair and the optical anisotropy of the hair’s structure. In addition, measurements on strands of human hair show a high reproducibility of the ellipsometric parameters for different hair fiber bundles from the same person. Based on the measurements, we develop a model of the dielectric function of hair that explains the spectra. This model includes the dielectric properties of the cuticle and cortex as well as their associated layer thicknesses. In addition, surface roughness effects modelled by a roughness layer with an complex refractive index given by an effective medium approach can have a significant effect on the measurements. We derive values for the parameters of the cuticle surface roughness layer of the thickness dACu= 273-360 nm and the air inclusion fA= 0.6 -5.7%. [1] accepted for publication in J. Biomed Opt., 2005

  6. Macroscopic effects of the spectral structure in turbulent flows

    NASA Astrophysics Data System (ADS)

    Tran, Tuan; Chakraborty, Pinaki; Guttenberg, Nicholas; Prescott, Alisia; Kellay, Hamid; Goldburg, Walter; Goldenfeld, Nigel; Gioia, Gustavo

    2010-06-01

    There is a missing link between the macroscopic properties of turbulent flows, such as the frictional drag of a wall-bounded flow, and the turbulent spectrum. The turbulent spectrum is a power law of exponent α (the `spectral exponent') that gives the characteristic velocity of a turbulent fluctuation (or `eddy') of size s as a function of s (ref. 1). Here we seek the missing link by comparing the frictional drag in soap-film flows, where α=3 (refs 9, 10), and in pipe flows, where α=5/3 (refs 11, 12). For moderate values of the Reynolds number Re, we find experimentally that in soap-film flows the frictional drag scales as Re-1/2, whereas in pipe flows the frictional drag scales as Re-1/4. Each of these scalings may be predicted from the attendant value of α by using a new theory, in which the frictional drag is explicitly linked to the turbulent spectrum.

  7. Hybrid quantum well/quantum dot structures for broad spectral bandwidth devices

    NASA Astrophysics Data System (ADS)

    Chen, Siming; Zhou, Kejia; Zhang, Ziyang; Childs, David T. D.; Orchard, Jonathan R.; Hogg, Richard A.; Kennedy, Kenneth; Hughes, Max.

    2012-02-01

    In this paper we report a hybrid quantum well (QW) and quantum dot (QD) structure to achieve a broad spontaneous emission and gain spectra. A single quantum well is introduced into a multi-layer stack of quantum dots, spectrally positioned to cancel the losses due to the second excited state of the dots. Attributed to the combined effect of QW and QDs, we show room temperature spontaneous emission with a 3dB bandwidth of ~250 nm and modal gain spanning over ~300 nm. We describe how this is achieved by careful design of the structure, balancing thermal emission from the QW and transport/capture processes in the QDs. We will also compare results from a QD-only epitaxial structure to describe how broadband gain/emission can be achieved in this new type of structure.

  8. Comparing spectral resolvability in chinchillas and human listeners using phase discrimination

    NASA Astrophysics Data System (ADS)

    Shofner, William P.; Sparks, Kathryn; Wu, Yuanxing Esther; Pham, Ellen

    2004-05-01

    A tone complex made of harmonic components that are added in cosine-starting phase can be discriminated from complexes comprised of identical harmonics that are added with random-starting phases. Phase discrimination occurs when unresolved harmonics interact within a single auditory channel. When harmonics are resolved, there is less interaction among components resulting in poorer phase discrimination performance. Thus, phase discrimination indirectly reflects spectral resolvability. Performance in a phase discrimination task was measured in chinchillas and human listeners to compare spectral resolvability between the two groups. Subjects discriminated a cosine-phase tone complex from random-phase tone complexes in a go/no-go behavioral paradigm. Tone complexes were comprised of a 250-Hz fundamental frequency and N consecutive higher harmonics, where N was 5, 10, 20, and 40. Performance was evaluated in terms of d'. The results show that the measured d' increased as N increased, and values of d' for each N condition were similar between chinchillas and human listeners. Values of the criterion for each N condition were also similar between chinchillas and humans. The results do not support the hypothesis that spectral resolvability is poorer in chinchillas, but suggest that resolvability is similar between the two groups. [Work supported by NIH/NIDCD.

  9. Modeling of PZT-induced Lamb wave propagation in structures by using a novel two-layer spectral finite element

    NASA Astrophysics Data System (ADS)

    Liu, Xiaotong; Zhou, Li; Ouyang, Qinghua

    2016-04-01

    This paper presents a novel two-layer spectral finite element model, consisting of PZT wafer and host structure, to simulate PZT-induced Lamb wave propagation in beam-like and plate-like structures. Based on the idea of equal displacement on the interface between PZT wafer and host structure, the one-dimensional spectral beam element of PZT-host beam and two-dimensional spectral plate element of PZT-host plate are considered as one hybrid element, respectively. A novel approach is proposed by taking the coupling effect of piezoelectric transducers in the thickness direction into account. The dynamic equation of the two-layer spectral element is derived from Hamilton's principle. Validity of the developed spectral finite element is verified through numerical simulation. The result indicates that, compared with the conventional finite element method (FEM) based on elasticity, the proposed spectral finite element is proved to have a high accuracy in modeling Lamb wave propagation, meanwhile, significantly improve the calculation efficiency.

  10. A comparative study of the performance of different spectral estimation methods for classification of mental tasks.

    PubMed

    Diez, Pablo F; Laciar, Eric; Mut, Vicente; Avila, Enrique; Torres, Abel

    2008-01-01

    In this paper we compare three different spectral estimation techniques for the classification of mental tasks. These techniques are the standard periodogram, the Welch periodogram and the Burg method, applied to electroencephalographic (EEG) signals. For each one of these methods we compute two parameters: the mean power and the root mean square (RMS), in various frequency bands. The classification of the mental tasks was conducted with a linear discriminate analysis. The Welch periodogram and the Burg method performed better than the standard periodogram. The use of the RMS allows better classification accuracy than the obtained with the power of EEG signals.

  11. Investigation on the coupling effect of thermochromism and microstructure on spectral properties of structured surfaces

    NASA Astrophysics Data System (ADS)

    Fang, Junfei; Xuan, Yimin; Li, Qiang; Fan, Desong; Huang, Jinguo

    2012-07-01

    This paper is aimed at studying the coupling effect of thermochromism and surface microstructure on the spectral properties of structured surfaces. We prepare the samples of structured surfaces of perovskite-type manganese thermochromic materials by patterning one-dimensional gratings and two-dimensional cavity arrays by means of the photolithographic technique. Experiment on radiative properties of these samples indicates that the emittance of the structured surfaces dramatically increases compared with that of the bulk thermochromic materials. It is demonstrated the adjustable emittance range of the thermochromic materials can be effectively enlarged by designing the surface morphology. This implies a novel approach for improving the thermochromic effect of the perovskite-type manganese materials.

  12. Structural and spectral comparisons between isomeric benzisothiazole and benzothiazole based aromatic heterocyclic dyes

    NASA Astrophysics Data System (ADS)

    Wang, Yin-Ge; Wang, Yue-Hua; Tao, Tao; Qian, Hui-Fen; Huang, Wei

    2015-09-01

    A pair of isomeric heterocyclic compounds, namely 3-amino-5-nitro-[2,1]-benzisothiazole and 2-amino-6-nitrobenzothiazole, are used as the diazonium components to couple with two N-substituted 4-aminobenzene derivatives. As a result, two pairs of isomeric aromatic heterocyclic azo dyes have been produced and they are structurally and spectrally characterized and compared including single-crystal structures, electronic spectra, solvatochromism and reversible acid-base discoloration, thermal stability and theoretically calculations. It is concluded that both benzisothiazole and benzothiazole based dyes show planar molecular structures and offset π-π stacking interactions, solvatochromism and reversible acid-base discoloration. Furthermore, benzisothiazole based aromatic heterocyclic dyes exhibit higher thermal stability, larger solvatochromic effects and maximum absorption wavelengths than corresponding benzothiazole based ones, which can be explained successfully by the differences of their calculated isomerization energy, dipole moment and molecular band gaps.

  13. Macroscopic effects of the spectral structure in turbulent flows

    NASA Astrophysics Data System (ADS)

    Tran, T.; Chakraborty, P.; Guttenberg, N.; Prescott, A.; Kellay, H.; Goldburg, W.; Goldenfeld, N.; Gioia, G.

    2010-11-01

    There is a missing link between macroscopic properties of turbulent flows, such as the frictional drag of a wall-bounded flow, and the turbulent spectrum. To seek the missing link we carry out unprecedented experimental measurements of the frictional drag in turbulent soap-film flows over smooth walls. These flows are effectively two-dimensional, and we are able to create soap-film flows with the two types of turbulent spectrum that are theoretically possible in two dimensions: the "enstrophy cascade," for which the spectral exponent α= 3, and the "inverse energy cascade," for which the spectral exponent α= 5/3. We find that the functional relation between the frictional drag f and the Reynolds number Re depends on the spectral exponent: where α= 3, f ˜Re-1/2; where α= 5/3, f ˜Re-1/4. Each of these scalings may be predicted from the attendant value of α by using a recently proposed spectral theory of the frictional drag. In this theory the frictional drag of turbulent flows on smooth walls is predicted to be f ˜Re^(1-α)/(1+α).

  14. Structural basis for the spectral difference in luciferase bioluminescence.

    PubMed

    Nakatsu, Toru; Ichiyama, Susumu; Hiratake, Jun; Saldanha, Adrian; Kobashi, Nobuyuki; Sakata, Kanzo; Kato, Hiroaki

    2006-03-16

    Fireflies communicate with each other by emitting yellow-green to yellow-orange brilliant light. The bioluminescence reaction, which uses luciferin, Mg-ATP and molecular oxygen to yield an electronically excited oxyluciferin species, is carried out by the enzyme luciferase. Visible light is emitted during relaxation of excited oxyluciferin to its ground state. The high quantum yield of the luciferin/luciferase reaction and the change in bioluminescence colour caused by subtle structural differences in luciferase have attracted much research interest. In fact, a single amino acid substitution in luciferase changes the emission colour from yellow-green to red. Although the crystal structure of luciferase from the North American firefly (Photinus pyralis) has been described, the detailed mechanism for the bioluminescence colour change is still unclear. Here we report the crystal structures of wild-type and red mutant (S286N) luciferases from the Japanese Genji-botaru (Luciola cruciata) in complex with a high-energy intermediate analogue, 5'-O-[N-(dehydroluciferyl)-sulfamoyl]adenosine (DLSA). Comparing these structures to those of the wild-type luciferase complexed with AMP plus oxyluciferin (products) reveals a significant conformational change in the wild-type enzyme but not in the red mutant. This conformational change involves movement of the hydrophobic side chain of Ile 288 towards the benzothiazole ring of DLSA. Our results indicate that the degree of molecular rigidity of the excited state of oxyluciferin, which is controlled by a transient movement of Ile 288, determines the colour of bioluminescence during the emission reaction.

  15. Structured-groove phase gratings for control and optimization of the spectral efficiency

    NASA Technical Reports Server (NTRS)

    Backlund, Johan; Wilson, Daniel W.; Muller, Richard E.

    2004-01-01

    Phase gratings are used as dispersers in a variety of imaging spectroscopic instruments. However, conventional phase gratings provide limited spectral range and flexibility to fully optimize instrument performance for challenging applications. Presented here is a new design method that tailors and optimizes the spectral efficiency by introducing an arbitrary structure into the grating groove profile.

  16. Systematic, map-scale, comparative structural geology

    SciTech Connect

    Groshong, R.H. Jr.

    1985-01-01

    Interpretation by analogy is the basis of comparative structural geology. A systematic approach to analog selection aids in efficiency and in understanding. The basic interpretive unit for analog selection is the structural family: a map-scale assemblage of genetically related structural forms produced by deformation with approximately constant boundary conditions. A family is specified by the dominant component of its displacement field and by structural levels involved. The differential vertical displacement category includes intrusive and impact structures. The three important basement types are isotropic crystalline, quasisedimentary and metamorphosing. A family is either thin skinned or involves cover plus one of the three basement types. These parameters are arranged into a matrix to produce 20 pigeon holes. Some structures do not fall exactly into one pigeon hole. Other structures link two families; for example, gravity glide links thin-skinned extension and contraction. This system is analogous to end-member rock classifications. Not every example is an end member, but the concept of end members greatly speeds up comparative analysis and clarifies the choice of analogies. Future research will lead to better definition of the key characteristics of certain families, the relationships between families, and the possible existence of additional families.

  17. Development of wideband spectral dispersers for exoplanetary science: comparative study of material, design, and fabrication

    NASA Astrophysics Data System (ADS)

    Enya, Keigo; Fujishiro, Naofumi

    2014-09-01

    We present the development of wideband spectral dispersers of which the primary scientific objective is the characterization of the atmospheres of exoplanets, including the challenge of detecting biomarkers. A disperser comprising a prism with a grating pattern on its surface provides simultaneous wideband coverage with low spectral resolution (R ≥ 300). The optics is simple, compact, and contains no moving parts. A comparative study of 21 materials for the disperser was carried out for use in the optical, near-infrared, and mid-infrared wavelength regions. KRS-5, CdZnTe, ZnS LiF, Sapphire, and S-TIH11 were selected, and designs of the optics for single-channel wideband spectrometers using the selected six materials were considered. Then, trial designs of the multi-channel spectrometers were carried out taking the properties of the detectors into consideration. The 3-channel design covers the wavelength region of ˜0.2-23 μm using a CCD detector, an InSb detector, and a Si:As detector. The 2-channel design covers ˜0.4-23 μm using a HgCdTe detector and a Si:As detector. A fabricated ZnS disperser is shown together with a CsI subprism which compensates for the optical axis. The application of defocusing, high dispersion spectroscopy, extension to the UV wavelength region, and the combination of the disperser with future space telescopes are discussed.

  18. Spectral analysis of the Forel-Ule Ocean colour comparator scale

    NASA Astrophysics Data System (ADS)

    Wernand, M. R.; van der Woerd, H. J.

    2010-04-01

    François Alphonse Forel (1890) and Willi Ule (1892) composed a colour comparator scale, with tints varying from indigo-blue to coca-cola brown, to quantify the colour of natural waters, like seas, lakes and rivers. For each measurement, the observer compares the colour of the water above a submersed white disc (Secchi disc) with the hand-held scale of pre-defined colours. The scale can be well reproduced from a simple recipe for twenty-one coloured chemical solutions and because the ease of its use, the Forel-Ule (FU) scale has been applied globally and intensively by oceanographers and limnologists from the year 1890. Indeed, the archived FU data belong to the oldest oceanographic data sets and do contain information on the changes in geobiophysical properties of natural waters during the last century. In this article we describe the optical properties of the FU-scale and its ability to cover the colours of natural waters, as observed by the human eye. The recipe of the scale and its reproduction is described. The spectral transmission of the tubes, with belonging chromaticity coordinates, is presented. The FU scale, in all its simplicity, is found to be an adequate ocean colour comparator scale. The scale is well characterized, is stable and observations are reproducible. This supports the idea that the large historic data base of FU measurements is coherent and well calibrated. Moreover, the scale can be coupled to contemporary multi-spectral observations with hand-held and satellite-based spectrometers.

  19. Spectral and structural studies of dimethylphenyl betaine hydrate

    NASA Astrophysics Data System (ADS)

    Szafran, M.; Ostrowska, K.; Katrusiak, A.; Dega-Szafran, Z.

    2014-07-01

    Hydrates of betaines can be divided into four groups depending on the interactions of their water molecules with the carboxylate group. Dimethylphenyl betaine crystallizes as monohydrate (1), in which water molecules mediate in hydrogen bonds between the carboxylate groups. The water molecules are H-bonded only to one oxygen atom of the dimethylphenyl betaine molecules and link them into a chain via two O(1 W)sbnd H⋯O hydrogen bonds of the lengths 2.779(2) and 2.846(2) Å. The structures of monomer (2) and dimer (4) hydrates in vacuum, and the structure of monomer (3) in an aqueous environment have been optimized by the B3LYP/6-311++G(d,p) approach and the geometrical results have been compared with the X-ray diffraction data of 1. The calculated IR frequencies for the optimized structure have been used for the assignments of FTIR bands, the broad absorption band in the range 3415-3230 cm-1 has been assigned to the O(1w)sbnd H⋯O hydrogen bonds. The correlations between the experimental 1H and 13C NMR chemical shifts (δexp) of 1 in D2O and the magnetic isotropic shielding constants (σcalc) calculated by the GIAO/B3LYP/6-311G++(d,p) approach, using the screening solvation model (COSMO), δexp = a + b σcalc, for optimized molecule 3 in water solution are linear and well reproduce the experimental chemical shifts.

  20. Saturn's system ices: a comparative spectral study by Cassini-VIMS

    NASA Astrophysics Data System (ADS)

    Filacchione, Gianrico; Capaccioni, Fabrizio; Clark, Roger N.; Cuzzi, Jeff N.; Cruikshank, Dale P.; Coradini, Angioletta; Cerroni, Priscilla; Tosi, Federico; Ciarniello, Mauro; Nicholson, Phil D.; McCord, Thomas B.; Brown, Robert H.; Buratti, Bonnie J.; Jaumann, Ralf; Stephan, Katrin

    2010-05-01

    The Visual and Infrared Mapping Spectrometer (VIMS) has observed the entire population of Saturnian icy objects, allowing a comparative analysis of the VIS-NIR spectral properties of the regular satellites (Mimas, Enceladus, Tethys, Dione, Rhea, Hyperion, Iapetus, Phoebe), minor moons (Atlas, Prometheus, Pandora, Janus, Epimetheus, Telesto, Calypso) and main rings (A, B, C and Cassini division). The results we present are derived from the entire dataset available after about 5 years of the Cassini mission, which consists of more than 2000 full-disk observations of the moons as well as several radial mosaics of the ring system. The spectra of Saturn's satellites are characterized by a step red slope in the 0.35-0.55 µm range, which is highly diagnostic of the presence of organic contaminants and darkening agents on icy surfaces; in the 0.55-0.95 µm range the spectra become more flat and featureless. In the IR range the water ice bands at 1.5-2.0-3.0 µm bands are evident everywhere, while the CO2 ice band at 4.26 µm is seen only on the three external satellites Hyperion, Iapetus and Phoebe. Some specific spectrophotometric indicators are chosen to retrieve the macroscopic properties of the ices: I/F continuum levels, 0.35-0.55 and 0.55-0.95 µm spectral slopes, H2O-CO2 ice band depths and band positions. By using these indicators the Saturn's satellites are grouped in distinct classes, noticeably between the almost pure water ice and blue surfaces of Enceladus and Calypso to the organic- and carbon dioxide-rich Hyperion, Iapetus and Phoebe. Hyperion and the leading hemisphere of Iapetus have the reddest VIS slopes of the group. Janus' visible colors are intermediate between these two classes having a slightly positive VIS spectral slope, while Epimetheus is more neutral and similar to Iapetus' bright terrains (trailing hemisphere), Mimas and Tethys. The two F ring's shepherd moons, Prometheus and Pandora, have similarities with Atlas, while Calypso and Telesto

  1. Spectral Variability and Cloud Structure in Luhman 16AB

    NASA Astrophysics Data System (ADS)

    Burgasser, Adam J.; Gillon, M.; Faherty, J. K.; Triaud, A.; Street, R.

    2014-01-01

    We report resolved near-infrared spectroscopic monitoring observations of the nearby L dwarf/T dwarf binary WISE J104915.57-531906.1AB (aka Luhman 16AB), as part of a broader campaign to characterize the spectral energy distribution and temporal variability of this source. A continuous 45-minute sequence of low-resolution spectra spanning 0.8-2.4 µm was obtained with IRTF/SpeX, concurrent with combined-light optical photometry with TRAPPIST. Our integrated spectral observations confirm the flux reversal of this binary, with the T dwarf secondary being brighter from 0.8-1.5 µm. We observe a wavelength-dependent decline in the relative fluxes of the two components over the course of the observation, concurrent with a decline in the optical brightness of the combined light system, variations that can be successfully modeled with both achromatic (brightness) and chromatic (color) variations in Luhma 16B, assuming Luhma 16A to be nonvariable. We estimate a peak-to-peak amplitude of 13.5% at 1.25 µm over the full lightcurve, intermediate in amplitude and period as the variable early-T dwarfs SIMP 0136+0933 and 2MASS J2139+0220 confirm the correlation suggested by Apai et al. assuming spot sizes are set by the atmospheric Rhines scale. Using a simple two-layer brightness-temperature model, we infer a cloud coverage fraction of 33--57% than varies by up to 50% assuming a 300 K difference between cool cloud tops and hot "holes". The strong variability of Luhman 16B combined with the relative spectral intensities of the A and B components support the model of a patchy disruption of the mineral cloud layer across the L dwarf/T dwarf transition.

  2. Spectral structure of electron antineutrinos from nuclear reactors.

    PubMed

    Dwyer, D A; Langford, T J

    2015-01-09

    Recent measurements of the positron energy spectrum obtained from inverse beta decay interactions of reactor electron antineutrinos show an excess in the 4 to 6 MeV region relative to current predictions. First-principles calculations of fission and beta decay processes within a typical pressurized water reactor core identify prominent fission daughter isotopes as a possible origin for this excess. These calculations also predict percent-level substructures in the antineutrino spectrum due to Coulomb effects in beta decay. Precise measurement of these substructures can elucidate the nuclear processes occurring within reactors. These substructures can be a systematic issue for measurements utilizing the detailed spectral shape.

  3. Spectral properties of the temporal evolution of brain network structure.

    PubMed

    Wang, Rong; Zhang, Zhen-Zhen; Ma, Jun; Yang, Yong; Lin, Pan; Wu, Ying

    2015-12-01

    The temporal evolution properties of the brain network are crucial for complex brain processes. In this paper, we investigate the differences in the dynamic brain network during resting and visual stimulation states in a task-positive subnetwork, task-negative subnetwork, and whole-brain network. The dynamic brain network is first constructed from human functional magnetic resonance imaging data based on the sliding window method, and then the eigenvalues corresponding to the network are calculated. We use eigenvalue analysis to analyze the global properties of eigenvalues and the random matrix theory (RMT) method to measure the local properties. For global properties, the shifting of the eigenvalue distribution and the decrease in the largest eigenvalue are linked to visual stimulation in all networks. For local properties, the short-range correlation in eigenvalues as measured by the nearest neighbor spacing distribution is not always sensitive to visual stimulation. However, the long-range correlation in eigenvalues as evaluated by spectral rigidity and number variance not only predicts the universal behavior of the dynamic brain network but also suggests non-consistent changes in different networks. These results demonstrate that the dynamic brain network is more random for the task-positive subnetwork and whole-brain network under visual stimulation but is more regular for the task-negative subnetwork. Our findings provide deeper insight into the importance of spectral properties in the functional brain network, especially the incomparable role of RMT in revealing the intrinsic properties of complex systems.

  4. Spectral properties of the temporal evolution of brain network structure

    NASA Astrophysics Data System (ADS)

    Wang, Rong; Zhang, Zhen-Zhen; Ma, Jun; Yang, Yong; Lin, Pan; Wu, Ying

    2015-12-01

    The temporal evolution properties of the brain network are crucial for complex brain processes. In this paper, we investigate the differences in the dynamic brain network during resting and visual stimulation states in a task-positive subnetwork, task-negative subnetwork, and whole-brain network. The dynamic brain network is first constructed from human functional magnetic resonance imaging data based on the sliding window method, and then the eigenvalues corresponding to the network are calculated. We use eigenvalue analysis to analyze the global properties of eigenvalues and the random matrix theory (RMT) method to measure the local properties. For global properties, the shifting of the eigenvalue distribution and the decrease in the largest eigenvalue are linked to visual stimulation in all networks. For local properties, the short-range correlation in eigenvalues as measured by the nearest neighbor spacing distribution is not always sensitive to visual stimulation. However, the long-range correlation in eigenvalues as evaluated by spectral rigidity and number variance not only predicts the universal behavior of the dynamic brain network but also suggests non-consistent changes in different networks. These results demonstrate that the dynamic brain network is more random for the task-positive subnetwork and whole-brain network under visual stimulation but is more regular for the task-negative subnetwork. Our findings provide deeper insight into the importance of spectral properties in the functional brain network, especially the incomparable role of RMT in revealing the intrinsic properties of complex systems.

  5. Heart rate variability in passive tilt test: comparative evaluation of autoregressive and FFT spectral analyses.

    PubMed

    Badilini, F; Maison-Blanche, P; Coumel, P

    1998-05-01

    The dynamic response of the autonomic nervous system during tilting is assessed by changes in the low (LF) and high frequency (HF) components of the RR series power spectral density (PSD). Although results of many studies are consistent, some doubts related to different methodologies remain. Specifically, the respective relevance of autoregressive (AR) and fast Fourier transform (FFT) methods is often questioned. Beat-to-beat RR series were recorded during 90 degrees passive tilt in 18 healthy subjects (29 +/- 5 years, eight females). FFT-based (50% overlap, Hanning window) and AR-based (Levinson-Durbin algorithm) PSDs were calculated on the same RR intervals. Powers in very low frequency (VLF: < 0.04 Hz), LF (0.04-0.15 Hz), and HF (0.15-0.40 Hz) bands were calculated either by spectrum integration (FFT and ARIN), by considering the highest AR component in each band (ARHP), or by summation of all AR components (ARAP). LF and HF raw powers (ms2) were normalized by total power (%P) and by total power after removal of the VLF component (nu). AR and FFT total powers were not different, regardless of body position. In supine condition, when compared to ARHP and ARAP, FFT underestimated VLF and overestimated LF, whereas in tilt position FFT overestimated HF and underestimated LF. However, supine/tilt trends were consistent in all methods showing a clear reduction of HF and a less marked increase of LF. Both normalization procedures provided a significant LF increase and further magnified the HF decrease. Results obtained with ARIN were remarkably close to those obtained with FFT. In conclusion, significant differences between AR and FFT spectral analyses do exist, particularly in supine position. Nevertheless, dynamic trends provided by the two approaches are consistent. Normalization is necessary to evidence the LF increase during tilt.

  6. Theory of satellite structures on spectral-line profiles.

    NASA Technical Reports Server (NTRS)

    Atakan, A. K.; Jacobson, H. C.

    1973-01-01

    A systematic comparison with experiment of various explanations for the problem of satellite-band formation on spectral-line profiles was initiated. The experiments were performed under a variety of conditions in an effort to construct a consistent model of entire line shapes. A composite theory is detailed which is the result of the insights of many individuals. The calculations indicate that the main features of the problem, the line, the high-intensity red satellites, and the blue satellite can be described simultaneously. The results also indicate that widely different potentials can lead to very similar line profiles. Ancillary conclusions are presented concerning the role of Lennard-Jones potentials in line-shape calculations.

  7. Structural, spectral and thermal analysis of some metallocephradines

    NASA Astrophysics Data System (ADS)

    Masoud, Mamdouh S.; Ali, Alaa E.; Ghareeb, Doaa A.; Nasr, Nessma M.

    2015-11-01

    A series of cephradine metal complexes were prepared and investigated by elemental analysis, IR, electronic spectra, magnetic susceptibility, ESR spectra, 1HNMR spectral studies and mass spectra. EDX patterns were carried out to emphasis the nature of the particles and the purity of products, while SEM is a sensitive tool used to justify on the microstructure and surface morphology. Thermal behavior of the synthesized complexes was illustrated by different techniques (TGA, DTA and DSC). The thermal decomposition of all the complexes ended with the formation of metal oxides and carbon residue as a final product. Also, the thermodynamic parameters and thermal transitions, such as glass transitions, crystallization and melting temperatures for cephradine and its metal complexes were evaluated and discussed. The entropy change values, ΔS#, showed that the transition states are more ordered than the reacting complexes.

  8. Verification of the Velocity Structure in Mexico Basin Using the H/V Spectral Ratio of Microtremors

    NASA Astrophysics Data System (ADS)

    Matsushima, S.; Sanchez-Sesma, F. J.; Nagashima, F.; Kawase, H.

    2011-12-01

    The authors have been proposing a new theory to calculate the Horizontal-to-Vertical (H/V) spectral ratio of microtremors assuming that the wave field is completely diffuse and have attempted to apply the theory to understand the observed microtremor data. It is anticipated that this new theory can be applied to detect the subsurface velocity structure beneath urban area. Precise information about the subsurface velocity structure is essential for predicting strong ground motion accurately, which is necessary to mitigate seismic disaster. Mexico basin, who witnessed severe damage during the 1985 Michoacán Earthquake (Ms 8.1) several hundreds of kilometers away from the source region, is an interesting location in which the reassessment of soil properties is urgent. Because of subsidence, having improved estimates of properties is mandatory. In order to estimate possible changes in the velocity structure in the Mexico basin, we measured microtremors at strong motion observation sites in Mexico City. At those sites, information about the velocity profiles are available. Using the obtained data, we derive observed H/V spectral ratio and compare it with the theoretical H/V spectral ratio to gauge the goodness of our new theory. First we compared the observed H/V spectral ratios for five stations to see the diverse characteristics of this measurement. Then we compared the observed H/V spectral ratios with the theoretical predictions to confirm our theory. We assumed the velocity model of previous surveys at the strong motions observation sites as an initial model. We were able to closely fit both the peak frequency and amplitude of the observed H/V spectral ratio, by the theoretical H/V spectral ratio calculated by our new method. These results show that we have a good initial model. However, the theoretical estimates need some improvement to perfectly fit the observed H/V spectral ratio. This may be an indication that the initial model needs some adjustments. We

  9. Earlier timbre processing of instrumental tones compared to equally complex spectrally rotated sounds as revealed by the mismatch negativity.

    PubMed

    Christmann, Corinna A; Lachmann, Thomas; Berti, Stefan

    2014-10-03

    Harmonically rich sounds have been shown to be processed more efficiently by the human brain compared to single sinusoidal tones. To control for stimulus complexity as a potentially confounding factor, tones and equally complex spectrally rotated sounds, have been used in the present study to investigate the role of the overtone series in sensory auditory processing in non-musicians. Timbre differences in instrumental tones with equal pitch elicited a MMN which was earlier compared to that elicited by the spectrally rotated sounds, indicating that harmonically rich tones are processed faster compared to non-musical sounds without an overtone series, even when pitch is not the relevant information.

  10. The complex ion structure of warm dense carbon measured by spectrally resolved x-ray scatteringa)

    NASA Astrophysics Data System (ADS)

    Kraus, D.; Vorberger, J.; Helfrich, J.; Gericke, D. O.; Bachmann, B.; Bagnoud, V.; Barbrel, B.; Blažević, A.; Carroll, D. C.; Cayzac, W.; Döppner, T.; Fletcher, L. B.; Frank, A.; Frydrych, S.; Gamboa, E. J.; Gauthier, M.; Göde, S.; Granados, E.; Gregori, G.; Hartley, N. J.; Kettle, B.; Lee, H. J.; Nagler, B.; Neumayer, P.; Notley, M. M.; Ortner, A.; Otten, A.; Ravasio, A.; Riley, D.; Roth, F.; Schaumann, G.; Schumacher, D.; Schumaker, W.; Siegenthaler, K.; Spindloe, C.; Wagner, F.; Wünsch, K.; Glenzer, S. H.; Roth, M.; Falcone, R. W.

    2015-05-01

    We present measurements of the complex ion structure of warm dense carbon close to the melting line at pressures around 100 GPa. High-pressure samples were created by laser-driven shock compression of graphite and probed by intense laser-generated x-ray sources with photon energies of 4.75 keV and 4.95 keV. High-efficiency crystal spectrometers allow for spectrally resolving the scattered radiation. Comparing the ratio of elastically and inelastically scattered radiation, we find evidence for a complex bonded liquid that is predicted by ab-initio quantum simulations showing the influence of chemical bonds under these conditions. Using graphite samples of different initial densities we demonstrate the capability of spectrally resolved x-ray scattering to monitor the carbon solid-liquid transition at relatively constant pressure of 150 GPa. Showing first single-pulse scattering spectra from cold graphite of unprecedented quality recorded at the Linac Coherent Light Source, we demonstrate the outstanding possibilities for future high-precision measurements at 4th Generation Light Sources.

  11. The complex ion structure of warm dense carbon measured by spectrally resolved x-ray scattering

    SciTech Connect

    Kraus, D.; Barbrel, B.; Falcone, R. W.; Vorberger, J.; Helfrich, J.; Frydrych, S.; Ortner, A.; Otten, A.; Roth, F.; Schaumann, G.; Schumacher, D.; Siegenthaler, K.; Wagner, F.; Roth, M.; Gericke, D. O.; Wünsch, K.; Bachmann, B.; Döppner, T.; Bagnoud, V.; Blažević, A.; and others

    2015-05-15

    We present measurements of the complex ion structure of warm dense carbon close to the melting line at pressures around 100 GPa. High-pressure samples were created by laser-driven shock compression of graphite and probed by intense laser-generated x-ray sources with photon energies of 4.75 keV and 4.95 keV. High-efficiency crystal spectrometers allow for spectrally resolving the scattered radiation. Comparing the ratio of elastically and inelastically scattered radiation, we find evidence for a complex bonded liquid that is predicted by ab-initio quantum simulations showing the influence of chemical bonds under these conditions. Using graphite samples of different initial densities we demonstrate the capability of spectrally resolved x-ray scattering to monitor the carbon solid-liquid transition at relatively constant pressure of 150 GPa. Showing first single-pulse scattering spectra from cold graphite of unprecedented quality recorded at the Linac Coherent Light Source, we demonstrate the outstanding possibilities for future high-precision measurements at 4th Generation Light Sources.

  12. Low Frequency Spectral Structure of X-shaped Radio Sources

    NASA Astrophysics Data System (ADS)

    Lal, D. V.; Rao, A. P.

    2005-12-01

    X-shaped radio galaxies are attributed to be formed by galactic mergers as the black holes of two galaxies fall into the merged system and form a bound system. Recent analysis of Giant Metrewave Radio Telescope low frequency data for an X-shaped source, 3C 223.1 has revealed an unusual result (Lal & Rao 2004). The radio morphologies of it at 240 and 610 MHz show well defined X-shape with a pair of active jets along the north-south axis and a pair of wings along the east-west axis, that pass symmetrically through the undetected radio core. The wings (or low surface brightness jets) have flatter spectral indices with respect to the high surface brightness jets, which confirms the earlier marginal result obtained at high frequency by Dennett-Thorpe et al. (2002). Although unusual, it is a valuable result which puts stringent constraints on the formation models and nature of these sources. We present preliminary results for two such sources.

  13. VLT FORS2 comparative transmission spectral survey of clear and cloudy exoplanet atmospheres

    NASA Astrophysics Data System (ADS)

    Nikolov, Nikolay; Sing, David; Gibson, Neale; Evans, Thomas; Barstow, Joanna Katy; Kataria, Tiffany; Wilson, Paul A.

    2016-10-01

    Transmission spectroscopy is a key to unlocking the secrets of close-in exoplanet atmospheres. Observations have started to unveil a vast diversity of irradiated giant planet atmospheres with clouds and hazes playing a definitive role across the entire mass and temperature regime. We have initiated a ground-based, multi-object transmission spectroscopy of a hand full of hot Jupiters, covering the wavelength range 360-850nm using the recently upgraded FOcal Reducer and Spectrograph (FORS2) mounted on the Very Large Telescope (VLT) at the European Southern Observatory (ESO). These targets were selected for comparative follow-up as their transmission spectra showed evidence for alkali metal absorption, based on the results of Hubble Space Telescope (HST) observations. This talk will discuss the first results from the programme, demonstrating excellent agreement between the transmission spectra measured from VLT and HST and further reinforce the findings of clear, cloudy and hazy atmospheres. More details will be discussed on the narrow alkali features obtained with FORS2 at higher resolution, revealing its high potential in securing optical transmission spectra. These FORS2 observations are the first ground-based detections of clear, cloudy and hazy hot-Jupiter atmosphere with a simultaneous detections of Na, K, and H2 Rayleigh scattering. Our program demonstrates the large potential of the instrument for optical transmission spectroscopy, capable of obtaining HST-quality light curves from the ground. Compared to HST, the larger aperture of VLT will allow for fainter targets to be observed and higher spectral resolution, which can greatly aid comparative exoplanet studies. This is important for further exploring the diversity of exoplanet atmospheres and is particularly complementary to the near- and mid-IR regime, to be covered by the upcoming James-Webb Space Telescope (JWST) and is readily applicable to less massive planets down to super-Earths.

  14. THE THREE-DIMENSIONAL STRUCTURE OF INTERIOR EJECTA IN CASSIOPEIA A AT HIGH SPECTRAL RESOLUTION

    SciTech Connect

    Isensee, Karl; Rudnick, Lawrence; DeLaney, Tracey; Smith, J. D.; Rho, Jeonghee; Reach, William T.; Kozasa, Takashi; Gomez, Haley E-mail: larry@astro.umn.ed E-mail: jd.smith@utoledo.ed E-mail: reach@ipac.caltech.ed E-mail: haley.morgan@astro.cf.ac.u

    2010-12-20

    We used the Spitzer Space Telescope's Infrared Spectrograph to create a high-resolution spectral map of the central region of the Cassiopeia A (Cas A) supernova remnant, allowing us to make a Doppler reconstruction of its three-dimensional structure. The ejecta responsible for this emission have not yet encountered the remnant's reverse shock or the circumstellar medium, making it an ideal laboratory for exploring the dynamics of the supernova explosion itself. We observe that the O, Si, and S ejecta can form both sheet-like structures and filaments. Si and O, which come from different nucleosynthetic layers of the star, are observed to be coincident in velocity space in some regions, and separated by 500 km s{sup -1} or more in others. Ejecta traveling toward us are, on average, {approx}900 km s{sup -1} slower than the material traveling away from us. We compare our observations to recent supernova explosion models and find that no single model can simultaneously reproduce all the observed features. However, models of different supernova explosions can collectively produce the observed geometries and structures of the interior emission. We use the results from the models to address the conditions during the supernova explosion, concentrating on asymmetries in the shock structure. We also predict that the back surface of Cas A will begin brightening in {approx}30 years, and the front surface in {approx}100 years.

  15. Investigation on spectral response of micro-cavity structure by symmetrical tapered fiber tips

    NASA Astrophysics Data System (ADS)

    Liu, Yan; Li, Yang; Yan, Xiaojun; Li, Weidong

    2016-06-01

    We proposed and experimentally demonstrated a micro-cavity structure made of symmetrical tapered fiber tips. The waist of a conventional fiber taper fabricated from heating and stretching technique is symmetrically cleaved, and the aligned fiber tips with air gap constitute a Fabry-Perot micro-cavity due to the reflection at the tip facet. The spectral responses of such micro-cavity structure have been investigated both in beam propagation models and experiments. The multibeam interference in the micro-cavity and the impact of the waist diameter and cavity length on the spectral response has been successfully demonstrated. And a micro-cavity structure with 45 μm waist diameter was experimentally achieved, the measured spectra agree well with the simulation ones, indicating that the spectral response of the micro-cavity structure is contributed by both the multibeam interference and the Fabry-Perot micro-cavity.

  16. Structural and spectral investigation of terbium molybdate nanophosphor.

    PubMed

    Mani, Kamal P; Vimal, G; Biju, P R; Joseph, Cyriac; Unnikrishnan, N V; Ittyachen, M A

    2015-09-05

    Terbium molybdate nanophosphors were synthesized through a facile sol-gel route. The structure of the phosphors was characterized by X-ray diffraction, Raman spectra and Fourier transform infrared spectroscopy analysis. The X-ray diffraction studies revealed that the structure of the nanophosphor gradually changes from monoclinic to orthorhombic phase as heated from 700 to 900 °C. High resolution transmission electron microscopy, SAED and EDS were also employed to characterize the size, crystallinity and composition of the samples. Detailed spectroscopic investigations were carried out by Judd-Ofelt analysis based on UV-Visible-NIR absorption and emission spectra. The luminescence spectra suggest that phosphors with orthorhombic structure have better luminescence properties than the monoclinic structure. The phosphors showed intense green emission under near-UV excitation due to the energy transfer from the host lattice to Tb(3+) ions. The CIE coordinates suggest enhanced color purity for green emission and short fluorescence decay values proposes the suitability for LED applications. These phosphors can be applied as promising candidates for blue and near-UV excited WLEDs.

  17. Structural and spectral investigation of terbium molybdate nanophosphor

    NASA Astrophysics Data System (ADS)

    Mani, Kamal P.; Vimal, G.; Biju, P. R.; Joseph, Cyriac; Unnikrishnan, N. V.; Ittyachen, M. A.

    2015-09-01

    Terbium molybdate nanophosphors were synthesized through a facile sol-gel route. The structure of the phosphors was characterized by X-ray diffraction, Raman spectra and Fourier transform infrared spectroscopy analysis. The X-ray diffraction studies revealed that the structure of the nanophosphor gradually changes from monoclinic to orthorhombic phase as heated from 700 to 900 °C. High resolution transmission electron microscopy, SAED and EDS were also employed to characterize the size, crystallinity and composition of the samples. Detailed spectroscopic investigations were carried out by Judd-Ofelt analysis based on UV-Visible-NIR absorption and emission spectra. The luminescence spectra suggest that phosphors with orthorhombic structure have better luminescence properties than the monoclinic structure. The phosphors showed intense green emission under near-UV excitation due to the energy transfer from the host lattice to Tb3+ ions. The CIE coordinates suggest enhanced color purity for green emission and short fluorescence decay values proposes the suitability for LED applications. These phosphors can be applied as promising candidates for blue and near-UV excited WLEDs.

  18. A Better Sunscreen: Structural Effects on Spectral Properties

    ERIC Educational Resources Information Center

    Huck, Lawrence A.; Leigh, William J.

    2010-01-01

    A modification of the mixed-aldol synthesis of dibenzylideneacetone, prepared from acetone and benzaldehyde, is described wherein acetone is replaced with a series of cyclic ketones with ring sizes of 5-7 carbons. The structural variations in the resulting conjugated ketones produce regular variations in the UV-vis absorption spectra. The choice…

  19. Fold assessment for comparative protein structure modeling

    PubMed Central

    Melo, Francisco; Sali, Andrej

    2007-01-01

    Accurate and automated assessment of both geometrical errors and incompleteness of comparative protein structure models is necessary for an adequate use of the models. Here, we describe a composite score for discriminating between models with the correct and incorrect fold. To find an accurate composite score, we designed and applied a genetic algorithm method that searched for a most informative subset of 21 input model features as well as their optimized nonlinear transformation into the composite score. The 21 input features included various statistical potential scores, stereochemistry quality descriptors, sequence alignment scores, geometrical descriptors, and measures of protein packing. The optimized composite score was found to depend on (1) a statistical potential z-score for residue accessibilities and distances, (2) model compactness, and (3) percentage sequence identity of the alignment used to build the model. The accuracy of the composite score was compared with the accuracy of assessment by single and combined features as well as by other commonly used assessment methods. The testing set was representative of models produced by automated comparative modeling on a genomic scale. The composite score performed better than any other tested score in terms of the maximum correct classification rate (i.e., 3.3% false positives and 2.5% false negatives) as well as the sensitivity and specificity across the whole range of thresholds. The composite score was implemented in our program MODELLER-8 and was used to assess models in the MODBASE database that contains comparative models for domains in approximately 1.3 million protein sequences. PMID:17905832

  20. Fold assessment for comparative protein structure modeling.

    PubMed

    Melo, Francisco; Sali, Andrej

    2007-11-01

    Accurate and automated assessment of both geometrical errors and incompleteness of comparative protein structure models is necessary for an adequate use of the models. Here, we describe a composite score for discriminating between models with the correct and incorrect fold. To find an accurate composite score, we designed and applied a genetic algorithm method that searched for a most informative subset of 21 input model features as well as their optimized nonlinear transformation into the composite score. The 21 input features included various statistical potential scores, stereochemistry quality descriptors, sequence alignment scores, geometrical descriptors, and measures of protein packing. The optimized composite score was found to depend on (1) a statistical potential z-score for residue accessibilities and distances, (2) model compactness, and (3) percentage sequence identity of the alignment used to build the model. The accuracy of the composite score was compared with the accuracy of assessment by single and combined features as well as by other commonly used assessment methods. The testing set was representative of models produced by automated comparative modeling on a genomic scale. The composite score performed better than any other tested score in terms of the maximum correct classification rate (i.e., 3.3% false positives and 2.5% false negatives) as well as the sensitivity and specificity across the whole range of thresholds. The composite score was implemented in our program MODELLER-8 and was used to assess models in the MODBASE database that contains comparative models for domains in approximately 1.3 million protein sequences.

  1. [Comparative hierarchic structure of the genetic language].

    PubMed

    Ratner, V A

    1993-05-01

    The genetical texts and genetic language are built according to hierarchic principle and contain no less than 6 levels of coding sequences, separated by marks of punctuation, separation and indication: codons, cistrons, scriptons, replicons, linkage groups, genomes. Each level has all the attributes of the language. This hierarchic system expresses some general properties and regularities. The rules of genetic language being determined, the variability of genetical texts is generated by block-modular combinatorics on each level. Between levels there are some intermediate sublevels and module types capable of being combined. The genetic language is compared with two different independent linguistic systems: human natural languages and artificial programming languages. Genetic language is a natural one by its origin, but it is a typical technical language of the functioning genetic regulatory system--by its predestination. All three linguistic systems under comparison have evident similarity of the organization principles and hierarchical structures. This argues for similarity of their principles of appearance and evolution.

  2. Spectral-collocation variational integrators

    NASA Astrophysics Data System (ADS)

    Li, Yiqun; Wu, Boying; Leok, Melvin

    2017-03-01

    Spectral methods are a popular choice for constructing numerical approximations for smooth problems, as they can achieve geometric rates of convergence and have a relatively small memory footprint. In this paper, we introduce a general framework to convert a spectral-collocation method into a shooting-based variational integrator for Hamiltonian systems. We also compare the proposed spectral-collocation variational integrators to spectral-collocation methods and Galerkin spectral variational integrators in terms of their ability to reproduce accurate trajectories in configuration and phase space, their ability to conserve momentum and energy, as well as the relative computational efficiency of these methods when applied to some classical Hamiltonian systems. In particular, we note that spectrally-accurate variational integrators, such as the Galerkin spectral variational integrators and the spectral-collocation variational integrators, combine the computational efficiency of spectral methods together with the geometric structure-preserving and long-time structural stability properties of symplectic integrators.

  3. Spectral and total temperature-dependent emissivities of few-layer structures on a metallic substrate.

    PubMed

    Blandre, Etienne; Chapuis, Pierre-Olivier; Vaillon, Rodolphe

    2016-01-25

    We investigate the thermal radiative emission of few-layer structures deposited on a metallic substrate and its dependence on temperature with the Fluctuational Electrodynamics approach. We highlight the impact of the variations of the optical properties of metallic layers on their temperature-dependent emissivity. Fabry-Pérot spectral selection involving at most two transparent layers and one thin reflective layer leads to well-defined peaks and to the amplification of the substrate emission. For a single Fabry-Pérot layer on a reflective substrate, an optimal thickness that maximizes the emissivity of the structure can be determined at each temperature. A thin lossy layer deposited on the previous structure can enhance interference phenomena, and the analysis of the participation of each layer to the emission shows that the thin layer is the main source of emission. Eventually, we investigate a system with two Fabry-Pérot layers and a metallic thin layer, and we show that an optimal architecture can be found. The total hemispherical emissivity can be increased by one order of magnitude compared to the substrate emissivity.

  4. Spectral and structural comparison between bright and dim green fluorescent proteins in Amphioxus

    PubMed Central

    Bomati, Erin K.; Haley, Joy E.; Noel, Joseph P.; Deheyn, Dimitri D.

    2014-01-01

    The cephalochordate Amphioxus naturally co-expresses fluorescent proteins (FPs) with different brightness, which thus offers the rare opportunity to identify FP molecular feature/s that are associated with greater/lower intensity of fluorescence. Here, we describe the spectral and structural characteristics of green FP (bfloGFPa1) with perfect (100%) quantum efficiency yielding to unprecedentedly-high brightness, and compare them to those of co-expressed bfloGFPc1 showing extremely-dim brightness due to low (0.1%) quantum efficiency. This direct comparison of structure-function relationship indicated that in the bright bfloGFPa1, a Tyrosine (Tyr159) promotes a ring flipping of a Tryptophan (Trp157) that in turn allows a cis-trans transformation of a Proline (Pro55). Consequently, the FP chromophore is pushed up, which comes with a slight tilt and increased stability. FPs are continuously engineered for improved biochemical and/or photonic properties, and this study provides new insight to the challenge of establishing a clear mechanistic understanding between chromophore structural environment and brightness level. PMID:24968921

  5. Spectral and structural comparison between bright and dim green fluorescent proteins in Amphioxus.

    PubMed

    Bomati, Erin K; Haley, Joy E; Noel, Joseph P; Deheyn, Dimitri D

    2014-06-27

    The cephalochordate Amphioxus naturally co-expresses fluorescent proteins (FPs) with different brightness, which thus offers the rare opportunity to identify FP molecular feature/s that are associated with greater/lower intensity of fluorescence. Here, we describe the spectral and structural characteristics of green FP (bfloGFPa1) with perfect (100%) quantum efficiency yielding to unprecedentedly-high brightness, and compare them to those of co-expressed bfloGFPc1 showing extremely-dim brightness due to low (0.1%) quantum efficiency. This direct comparison of structure-function relationship indicated that in the bright bfloGFPa1, a Tyrosine (Tyr159) promotes a ring flipping of a Tryptophan (Trp157) that in turn allows a cis-trans transformation of a Proline (Pro55). Consequently, the FP chromophore is pushed up, which comes with a slight tilt and increased stability. FPs are continuously engineered for improved biochemical and/or photonic properties, and this study provides new insight to the challenge of establishing a clear mechanistic understanding between chromophore structural environment and brightness level.

  6. Spectral and source structural development of mu and alpha rhythms from infancy through adulthood

    PubMed Central

    Thorpe, Samuel G.; Cannon, Erin N.; Fox, Nathan A.

    2016-01-01

    Objective To assess the developmental trajectory of spectral, topographic, and source structural properties of functional mu desynchronization (characterized during voluntary reaching/grasping movement), and investigate its spectral/topographic relation to spontaneous EEG in the developing alpha band. Methods Event related desynchronization (ERD) and power spectral density spectra/topography are analyzed in twelve month-old infants, four year-old children, and adults. Age-matched head models derived from structural MRI are used to obtain current density reconstructions of mu desynchronization across the cortical surface. Results Infant/child EEG contains spectral peaks evident in both the upper and lower developing alpha band, and spectral/topographic properties of functionally identified mu rhythm strongly reflect those of upper alpha in all subject groups. Source reconstructions show distributed frontoparietal patterns of cortical mu desynchronization concentrated in specific central and parietal regions which are consistent across age groups. Conclusions Peak frequencies of mu desynchronization and spontaneous alpha band EEG increase with age, and characteristic mu topography/source-structure is evident in development at least as early as twelve months. Significance Results provide evidence for a cortically distributed functional mu network, with spontaneous activity measurable in the upper alpha band throughout development. PMID:25910852

  7. SPECTRAL PROPERTIES OF REGIONS AND STRUCTURES IN THE INTERSTELLAR BOUNDARY EXPLORER (IBEX) SKY MAPS

    SciTech Connect

    Dayeh, M. A.; McComas, D. J.; Livadiotis, G.; Ebert, R. W.; Schwadron, N. A.; Funsten, H. O.; Janzen, P.; Reisenfeld, D. B.

    2011-06-10

    We study the spectral properties of different regions and structures in the energetic neutral atom (ENA) maps at energies from {approx}0.5 keV to {approx}6 keV from the Interstellar Boundary Explorer (IBEX) mission. We find that (1) an ankle-shaped break (spectrum hardens) between {approx}1 keV and {approx}2 keV characterizes the polar spectra and the right flank, while a knee-shaped break (spectrum softens) describes the ribbon, nose, and the front region spectra; (2) the spectral indices across full latitudinal range (tail and poles) comprise a dependence reflecting a knee break at mid latitudes and an ankle break at high latitudes. This latitudinal evolution has inflection points at {approx}40 deg. S and {approx}36 deg. N, and is strongly correlated with the solar wind speed structure obtained by the Ulysses/SWOOPS instrument during its fast latitude scan in 2007. Our study confirms that the ecliptic latitude predominantly orders the spectral signatures of ENA distributions. This ordering may reflect the average solar wind properties that vary characteristically with latitude around solar minimum. We report on the spectral analyses of six regions and two structures in the IBEX maps. We also discuss the spectral asymmetries between the north and the south polar regions, their correlation with solar wind measurements, and the implications of these observations. Thus, we show detailed connections between the IBEX energy spectra and latitudinal properties of solar wind.

  8. Band-structural and Fourier-spectral properties of one-dimensional generalized Fibonacci lattices

    NASA Astrophysics Data System (ADS)

    Oh, G. Y.; Lee, M. H.

    1993-11-01

    We study the electronic and Fourier-spectral properties of one-dimensional generalized Fibonacci lattices generated by the stacking rule Sl+1=SnlSml-1 with positive integers n and m, where Sl is the lth generational binary sequence. After showing that, in the limit of the large potential strength, the energy spectrum of a lattice with certain specific n and m can be determined by the associated characteristic value τ(n,m), we investigate the relation between the electronic band structure and the Fourier spectrum. When the lattice possesses the Pisot-Vijayaraghavan (PV) property (i.e., when n+1>m), the Fourier spectrum is closely related to the electronic band structure; the location and the relative strength of the Fourier spectral peak is in agreement with the location and the relative width of the energy spectral gap. On the other hand, when the lattice possesses no PV property (i.e., when n+1<=m), the Fourier spectrum is not directly related to the electronic band structure; the strength of the Fourier spectral peak is irrelevant to the width of the energy spectral gap, while the location of the peak corresponds to that of the gap. We also study the dependence of the electronic and Fourier-spectral properties on the initial conditions of the stacking rule through detailed study of the copper mean lattice (n=1,m=2) with initial conditions S1=\\{A\\} and S2=\\{ABp\\}. It is found that the fractal structure of the energy spectrum is independent of the integer p, while some local electronic properties depend on p. It is also found that the global structure of the Fourier spectrum depends on p; it looks more blurred, and thus the aperiodic nature of the lattice becomes clearer with the increase of p.

  9. Spectral Graph Analyses of Water Hydrogen-Bonding Network and Osmolyte Aggregate Structures in Osmolyte-Water Solutions.

    PubMed

    Lee, Hochan; Choi, Jun-Ho; Verma, Pramod Kumar; Cho, Minhaeng

    2015-11-12

    Recently, it was shown that the spectral graph theory is exceptionally useful for understanding not only morphological structural differences in ion aggregates but also similarities between an ion network and a water H-bonding network in highly concentrated salt solutions. Here, we present spectral graph analysis results on osmolyte aggregates and water H-bonding network structures in aqueous renal osmolyte solutions. The quantitative analyses of the adjacency matrices that are graph-theoretical representations of aggregates of osmolyte molecules and water H-bond structures provide the ensemble average eigenvalue spectra and degree distribution. We show that urea molecules form quite different morphological structures compared to other protecting renal osmolyte molecules in water, particularly sorbitol and trimethylglycine, which are well-known protecting osmolytes, and at high concentrations exhibit a strong propensity to form morphological structures that are graph-theoretically similar to that of the water H-bond network. Conversely, urea molecules, even at similarly high concentrations, form separated clusters instead of extended osmolyte-osmolyte networks. This difference in morphological structure of osmolyte-osmolyte aggregates between protecting and destabilizing osmolytes is considered to be an important observation that led us to propose a hypothesis on the osmolyte aggregate growth mechanism via either osmolyte network formation or segregated osmolyte cluster formation. We anticipate that the present spectral graph analyses of osmolyte aggregate structures and their interplay with the water H-bond network structure in highly concentrated renal osmolyte solutions could provide important information on the osmolyte effects of not only water structures but also protein stability in biologically relevant osmolyte solutions.

  10. Structural and spectral analysis of 3-metoxytyramine, an important metabolite of dopamine

    NASA Astrophysics Data System (ADS)

    Dimić, Dušan; Milenković, Dejan; Marković, Zoran; Marković, Jasmina Dimitrić

    2017-04-01

    Density functional theory calculations, with B3LYP functional and 6-311++G(d,p) basis set are performed with the aim to support the molecular structure and the spectroscopic characteristics of 3-methoxytyramine, the major extracellular metabolite of dopamine. Natural Bond Orbital (NBO) and Quantum Theory of Atoms in Molecules (QTAIM) analysis were used to explain the specific interactions in the most stable conformations in vacuum and water. The conformer resembling the crystallographic structure was compared to the experimentally available data and NMR spectra. The detailed vibrational spectral analysis and the assignments of the bands, done on the best-fit basis comparison of the experimentally obtained and theoretically calculated IR and Raman spectra, match quite well indicating DFT calculations as very accurate source of normal mode assignments. The obtained results demonstrate the applicability and performance of DFT calculations in conformational analysis of 3-methoxytyramine at the state of the isolated molecule. The molecular docking showed that the most stable conformation in vacuum was not the most stable one when docked in protein, proving that only the weak interactions stabilize the gaseous phase conformations.

  11. Spectral structures and their generation mechanisms for solar radio type-I bursts

    SciTech Connect

    Iwai, K.; Miyoshi, Y.; Masuda, S.; Tsuchiya, F.; Morioka, A.; Misawa, H.

    2014-07-01

    The fine spectral structures of solar radio type-I bursts were observed by the solar radio telescope AMATERAS. The spectral characteristics, such as the peak flux, duration, and bandwidth, of the individual burst elements were satisfactorily detected by the highly resolved spectral data of AMATERAS with the burst detection algorithm that is improved in this study. The peak flux of the type-I bursts followed a power-law distribution with a spectral index of 2.9-3.3, whereas their duration and bandwidth were distributed more exponentially. There were almost no correlations between the peak flux, duration, and bandwidth. That means there was no similarity in the shapes of the burst spectral structures. We defined the growth rate of a burst as the ratio between its peak flux and duration. There was a strong correlation between the growth rate and peak flux. These results suggest that the free energy of type-I bursts that is originally generated by nonthermal electrons is modulated in the subsequent stages of the generation of nonthermal electrons, such as plasma wave generation, radio wave emissions, and propagation. The variation of the timescale of the growth rate is significantly larger than that of the coronal environments. These results can be explained by the situation wherein the source region may have the inhomogeneity of an ambient plasma environment, such as the boundary of open and closed field lines, and the superposition of entire emitted bursts was observed by the spectrometer.

  12. Introducing Spectral Structure Activity Relationship (S-SAR) Analysis. Application to Ecotoxicology

    PubMed Central

    Putz, Mihai V.; Lacrămă, Ana-Maria

    2007-01-01

    A novel quantitative structure-activity (property) relationship model, namely Spectral-SAR, is presented in an exclusive algebraic way replacing the old-fashioned multi-regression one. The actual S-SAR method interprets structural descriptors as vectors in a generic data space that is further mapped into a full orthogonal space by means of the Gram-Schmidt algorithm. Then, by coordinated transformation between the data and orthogonal spaces, the S-SAR equation is given under simple determinant form for any chemical-biological interactions under study. While proving to give the same analytical equation and correlation results with standard multivariate statistics, the actual S-SAR frame allows the introduction of the spectral norm as a valid substitute for the correlation factor, while also having the advantage to design the various related SAR models through the introduced “minimal spectral path” rule. An application is given performing a complete S-SAR analysis upon the Tetrahymena pyriformis ciliate species employing its reported eco-toxicity activities among relevant classes of xenobiotics. By representing the spectral norm of the endpoint models against the concerned structural coordinates, the obtained S-SAR endpoints hierarchy scheme opens the perspective to further design the ecotoxicological test batteries with organisms from different species.

  13. Comparing Factor Structures of Adolescent Psychopathology

    ERIC Educational Resources Information Center

    Verona, Edelyn; Javdani, Shabnam; Sprague, Jenessa

    2011-01-01

    Research on the structure of adolescent psychopathology can provide information on broad factors that underlie different forms of maladjustment in youths. Multiple studies from the literature on adult populations suggest that 2 factors, Internalizing and Externalizing, meaningfully comprise the factor structure of adult psychopathology (e.g.,…

  14. Ion Spectral Structures Observed by the Van Allen Probes and Cluster

    NASA Astrophysics Data System (ADS)

    Ferradas, C.; Zhang, J.; Luo, H.; Kistler, L. M.; Spence, H. E.; Larsen, B.; Skoug, R. M.; Funsten, H. O.; Reeves, G. D.

    2014-12-01

    During the last decades several missions have recorded the presence of dynamic spectral features of energetic ions in the inner magnetosphere. Previous studies have revealed single "nose-like" structures occurring alone and simultaneous nose-like structures (up to three). In this study we also include signatures of new types of ion structure, namely "trunk-like" and "tusk-like" structures. All the ion structures are named after the characteristic shapes of energy bands or gaps in the energy-time spectrograms of in situ measured ion fluxes. They constitute the observational signatures of ion acceleration, transport, and loss in the global magnetosphere. Multi-spacecraft analysis of these structures is important to understand their spatial distribution and temporal evolution. Mass spectrometers onboard Cluster (in a polar orbit) and the Van Allen Probes (in an equatorial orbit) measure energetic hydrogen, helium, and oxygen ions near the inner edge of the plasma sheet, where these ion structures are observed. We present a statistical study of the ion structures, using >1-year measurements from the two missions during the Van Allen Probes era. The results provide important details about the spatial distribution (dependence on geocentric distance and magnetic local time), spectral features of the structures (e.g., characteristic energy and differences among species), and geomagnetic and solar wind conditions under which these structures occur.

  15. Comparative studies on solar cell structures using zinc phthalocyanine and fullerenes

    NASA Astrophysics Data System (ADS)

    Egginger, M.; Koeppe, R.; Meghdadi, F.; Troshin, P. A.; Lyubovskaya, R. N.; Meissner, D.; Sariciftci, N. S.

    2006-04-01

    We compare different structures of organic solar cells based on zinc phthalocyanine (ZnPc) and fullerene derivatives as electron donor and acceptor materials, respectively. Bilayer devices are fabricated and characterized by current-voltage and spectrally resolved photocurrent measurements. In a novel approach, the ZnPc was combined with soluble fullerene derivatives. With a pyrrolidinofullerene bearing chelating pyrridyl-groups we observed a complexation between donor and acceptor molecules. Due to a favorable structuring of the donor-acceptor interface this leads to a significant enhancement of the solar cell performance compared to similar devices where no complexation takes place. Coevaporated bulk heterojunction mixed-layers are introduced between the pristine layers. In these optimized structures short circuit currents up to 13 mA/cm2 are observed. We investigate the voltage dependence of the spectrally resolved photocurrent of ZnPc / Buckminsterfullerene bilayer solar cells and interpret the results in terms of the Gartner model.

  16. Studies on azaspiracid biotoxins. II. Mass spectral behavior and structural elucidation of azaspiracid analogs.

    PubMed

    Brombacher, Stephan; Edmonds, Suzanne; Volmer, Dietrich A

    2002-01-01

    In this report, the mass spectral analysis of azaspiracid biotoxins is described. Specifically, the collision-induced dissociation (CID) behavior and differences between CID spectra obtained on a triple-quadrupole, a quadrupole time-of-flight, and an ion-trap mass spectrometer are addressed here. The CID spectra obtained on the triple-quadrupole mass spectrometer allowed the classification of the major product ions of the five investigated compounds (AZA 1-5) into five distinct fragment ion groups, according to the backbone cleavage positions. Although the identification of unknown azaspiracids was difficult based on CID alone, the spectra provided sufficient structural information to allow confirmation of known azaspiracids in marine samples. Furthermore, we were able to detect two new azaspiracid analogs (AZA 1b and 6) in our samples and provide a preliminary structural analysis. The proposed dissociation pathways under tandem mass spectrometry (MS/MS) conditions were confirmed by a comparison with accurate mass data from electrospray quadrupole time-of-flight MS/MS experiments. Regular sequential MS(n) analysis on an ion-trap mass spectrometer was more restricted in comparison to the triple-quadrupole mass spectrometer, because the azaspiracids underwent multiple [M + H - nH(2)O](+) (n = 1-6) losses from the precursor ion under CID. Thus, the structural information obtained from MS(n) experiments was somewhat limited. To overcome this limitation, we developed a wide-range excitation technique using a 180-u window that provided results comparable to the triple-quadrupole instrument. To demonstrate the potential of the method, we applied it to the analysis of degraded azaspiracids from mussel tissue extracts.

  17. An intelligent system for comparing protein structures

    SciTech Connect

    Benatan, E.

    1994-12-31

    An approach to protein structure comparison is presented which uses techniques of artificial intelligence (AI) to generate a mapping between two protein structures. The approach proceeds by first identifying the seed of a possible mapping, and then searching for ways to extend the seed by incorporating corresponding elements from the two proteins. Correspondence is judged using heuristic functions which assess the similarity of the structural environments of the elements. The search can be guided by separately encoded knowledge. A prototype has been implemented which is able to rapidly create mappings with a high degree of accuracy in test cases.

  18. Spectral ratio techniques as a tool for soil-structure interaction assessment

    NASA Astrophysics Data System (ADS)

    Ladina, C.; Lovati, S.; Marzorati, S.; Massa, M.

    2009-04-01

    structure, is built on lithological units characterized by alluvial deposits. All noise measurements, characterized by a minimum duration of 30 minutes (sampling rate 100 Hz), were performed using a Lennartz LE3D-5s seismometer (flat response 0.2 - 40 Hz) coupled with a 24 bits Reftek 130/01 digital recorder. To investigate the dynamic characterization of buildings both standard spectral ratio (SSR) and horizontal to vertical spectral ratio (HVNR) techniques were applied to the recorded data; in the first case two simultaneous measures, computed at the bottom and at the top of the structure were considered. For the stations where earthquakes recordings were available, the results from ambients noise were compared, to those obtained from earthquakes (HVSR). For all records the linear trend and the instrumental response were removed and a band-pass Butterworth 4 poles filter between 0.2 and 25 Hz was applied. Then each component of noise was windowed in time series of 120 s length (cosine taper 5%), the horizontal components were rotated between 0° and 175° with step of 5° and the power spectral density (PSD) were calculated using a Konno and Ohmachi (1998) window (b=20). Finally, for each considered azimuth average HVNRs were computed calculating for each time window the spectral ratio between the spectrum of the radial component over the spectrum of the vertical one. For earthquake the data processing were performed as described for noise but considering different portion of signal: 5 s and 15 s of S waves, starting 0.5 s before the S-waves picking, and 20 s of coda were selected. Also in this case for each selected window HVSR were calculated through a directional analysis as that described for HVNR. The results highlight the fundamental role of the installation. For BAG8 and AUL, where the sensors are directly installed on rock, the vibrations of the structure do not affect HVNR at the bottom, which show flat responses in the whole frequency range: in both cases the

  19. Reactance, Restoration, and Cognitive Structure: Comparative Statics

    ERIC Educational Resources Information Center

    Bessarabova, Elena; Fink, Edward L.; Turner, Monique

    2013-01-01

    This study (N = 143) examined the effects of freedom threat on cognitive structures, using recycling as its topic. The results of a 2(Freedom Threat: low vs. high) x 2(Postscript: restoration vs. filler) plus 1(Control) experiment indicated that, relative to the control condition, high freedom threat created a boomerang effect for the targeted…

  20. Uncertainty of Comparative Judgments and Multidimensional Structure

    ERIC Educational Resources Information Center

    Sjoberg, Lennart

    1975-01-01

    An analysis of preferences with respect to silhouette drawings of nude females is presented. Systematic intransitivities were discovered. The dispersions of differences (comparatal dispersons) were shown to reflect the multidimensional structure of the stimuli, a finding expected on the basis of prior work. (Author)

  1. Structural and spectral response of Aequorea victoria green fluorescent proteins to chromophore fluorination.

    PubMed

    Pal, Prajna P; Bae, Jae Hyun; Azim, M Kamran; Hess, Petra; Friedrich, Rainer; Huber, Robert; Moroder, Luis; Budisa, Nediljko

    2005-03-15

    Global replacements of tyrosine by 2- and 3-fluorotyrosine in "enhanced green" and "enhanced yellow" mutants of Aequorea victoria green fluorescent proteins (avGFPs) provided protein variants with novel biophysical properties. While crystallographic and modeled structures of these proteins are indistinguishable from those of their native counterparts (i.e., they are perfectly isomorphous), there are considerable differences in their spectroscopic properties. The fluorine being an integral part of the avGFP chromophore induces changes in the titration curves, variations in the intensity of the absorbance and fluorescence, and spectral shifts in the emission maxima. Furthermore, targeted fluorination in close proximity to the fluorinated chromophore yielded additional variants with considerably enhanced spectral changes. These unique spectral properties are intrinsic features of the fluorinated avGFPs, in the context of the rigid chromophore-microenvironment interactions. The availability of the isomorpohous crystal structures of fluorinated avGFPs allowed mapping of novel, unusual interaction distances created by the presence of fluorine atoms. In addition, fluorine atoms in the ortho position of the chromophore tyrosyl moiety exhibit a single conformation, while in the meta position two conformer states were observed in the crystalline state. Such global replacements in chromophores of avGFPs and similar proteins result in "atomic mutations" (i.e., H --> F replacements) in the structures, offering unprecedented opportunities to understand and manipulate the relationships between protein structure and spectroscopic properties.

  2. Differential visualisation of a spectrally selective structure of strongly scattering objects

    SciTech Connect

    Kuratov, A S; Rudenko, V N; Shuvalov, V V

    2014-07-31

    We describe a modification of the algorithm for the fast approximate solution of the diffuse optical tomography inverse problem. In this modification the amount of a priori (auxiliary) information necessary for the visualisation of the internal structure of the object is reduced by using a differential measurement scheme. The experiment is performed at two different wavelengths, and some a priori information, necessary to reconstruct only the spectrally selective component of the internal structure (the difference structure of the spatial distributions of the extinction coefficient at the wavelength employed), is replaced by the data of one of these measurements. (laser biophotonics)

  3. Structural and spectral characterizations of C1C2 channelrhodopsin and its mutants by molecular simulations

    NASA Astrophysics Data System (ADS)

    Kamiya, Motoshi; Kato, Hideaki E.; Ishitani, Ryuichiro; Nureki, Osamu; Hayashi, Shigehiko

    2013-01-01

    Molecular dynamics (MD) simulations and excitation energy calculations of C1C2 chimera channelrhodopsin, a light-gated ion channel protein utilized as a biotechnological tool for optogenetics, based on a protein structure determined recently by X-ray crystallography were performed to investigate its structural and spectral properties. The MD simulations showed stability of hydrogen-bonds responsible for the channel gating observed in the crystallographic structural model. Analysis of electrostatic contribution of the surrounding protein groups to the absorption energy proposes several site-specific mutations that shift absorption maxima significantly, and provides a clear and controlled guide for engineering design of color variant proteins utilized in optogenetics.

  4. Spectral structure of 5 year time series of horizontal wind speed at the Boulder Atmospheric Observatory

    NASA Astrophysics Data System (ADS)

    Kang, Song-Lak; Won, Hoonill

    2016-10-01

    We investigate the spectral structures of 5 year, 1 min time series of horizontal wind speeds at 100 and 10 m heights at the Boulder Atmospheric Observatory tower located in the eastern slope of the Rocky Mountains, USA. In the full-scale spectra, the diurnal spectral peak, which is usually insignificant at a coastal or offshore site, is the most significant at both heights. The spectrum is enhanced on the low-frequency side of the diurnal peak during winter, but on the high-frequency side during summer, which indicates frequent synoptic weather events during winter supplanted by mesoscale events during summer. In terms of the spectral density in the spectral gap of Van der Hoven (1957), separating boundary layer turbulence from the synoptic-scale fluctuations, at a frequency between 10-4 and 10-3 Hz, we rank the daily time series at 100 m height and sample the summer top and winter bottom 10 percentile cases. The winter cases of the reduced spectral density in the gap region present the f-3 spectrum (f is frequency) and negatively skewed velocity increment distributions, which are the signatures of enstrophy (the integral of squared vorticity) cascade of turbulent two-dimensional (2-D) flows. In contrast, the summer cases of the enhanced spectral density present the f-5/3 spectrum and positively skewed velocity increment distributions, which are the signatures of upscale energy cascade of 2-D flows. In these mesoscale events that fill up the gap, the turbulence intensity-wind speed relationship is very sensitive to the choice of the averaging period.

  5. Spectral and structural stability properties of charged particle dynamics in coupled lattices

    SciTech Connect

    Qin, Hong; Chung, Moses; Davidson, Ronald C.; Burby, Joshua W.

    2015-05-15

    It has been realized in recent years that coupled focusing lattices in accelerators and storage rings have significant advantages over conventional uncoupled focusing lattices, especially for high-intensity charged particle beams. A theoretical framework and associated tools for analyzing the spectral and structural stability properties of coupled lattices are formulated in this paper, based on the recently developed generalized Courant-Snyder theory for coupled lattices. It is shown that for periodic coupled lattices that are spectrally and structurally stable, the matrix envelope equation must admit matched solutions. Using the technique of normal form and pre-Iwasawa decomposition, a new method is developed to replace the (inefficient) shooting method for finding matched solutions for the matrix envelope equation. Stability properties of a continuously rotating quadrupole lattice are investigated. The Krein collision process for destabilization of the lattice is demonstrated.

  6. Compare, Contrast, Comprehend: Using Compare-Contrast Text Structures with ELLs in K-3 Classrooms

    ERIC Educational Resources Information Center

    Dreher, Mariam Jean; Gray, Jennifer Letcher

    2009-01-01

    In this article, we describe how to help primary-grade English language learners use compare-contrast text structures. Specifically, we explain (a) how to teach students to identify the compare-contrast text structure, and to use this structure to support their comprehension, (b) how to use compare-contrast texts to activate and extend students'…

  7. Modeling of wave propagation in plate structures using three-dimensional spectral element method for damage detection

    NASA Astrophysics Data System (ADS)

    Peng, Haikuo; Meng, Guang; Li, Fucai

    2009-03-01

    This paper presents the application of three-dimensional (3-D) spectral element method (SEM) to wave propagation problems in plate structures for the purpose of damage detection. The excellent characteristic of the SEM is that the mass matrix is diagonal because of the choice of Lagrange interpolation function supported on the Gauss-Lobatto-Legendre (GLL) points in conjunction with the GLL integration rule. Therefore, numerical calculation can be significantly efficient in comparison with the classical finite element method (FEM). By taking advantage of this characteristic, a 3-D spectral finite elements (SFEs)-based model is developed to simulate the wave propagation in plate structures. Lamb waves, propagating in aluminum plates with and without a crack are investigated. Responses from 3-D SFEs- and 2-D SFEs-based models are compared. Different Lamb wave modes are generated using different excitation approaches and, subsequently, characteristics of those modes are analyzed. The results demonstrate that the proposed model can offer efficient and realistic simulation for Lamb wave propagation in plate structures, so as to detect damages in those structures.

  8. Electroencephalography Spectral Power Density in First-Episode Mania: A Comparative Study with Subsequent Remission Period

    PubMed Central

    GÜVEN, Sertaç; KESEBİR, Sermin; DEMİRER, R. Murat; BİLİCİ, Mustafa

    2015-01-01

    Introduction Our aim in this study was to investigate spectral power density (PSD) in first-episode mania and subsequent remission period and to evaluate their difference. Methods Sixty-nine consecutive cases referring to our hospital within the previous 1 year, who were evaluated as bipolar disorder manic episode according to The Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV) at the first episode and had the informed consent form signed by first degree relatives, were included in this study. Exclusion criteria included having previous depressive episode, using drugs which could influence electroencephalographic activity before electroencephalography (EEG), and having previous neurological disease, particularly epilepsy, head trauma, and/or loss of consciousness. EEG records were obtained using a digital device in 16 channels; 23 surface electrodes were placed according to the International 10–20 system. Spectral power density (dbμV/Hz) of EEG signal provided information on the power carried out by EEG waves in defined frequancy range per unit frequency in the present study. Results A peak power value detected on the right with FP2P4 and on the left with F7T3 electrodes were found to be higher in the manic episode than in the remission period (p=0.018 and 0.025). In the remission period, in cases with psychotic symptoms during the manic period, F4C4 peak power value was found to be lower than that in cases with no psychotic findings during the manic period (p=0.027). There was no relation was found between YMRS scores and peak power scores. Conclusion Electrophysiological corollary of mood episode is present from the onset of the disease, and it differs between the manic and remission periods of bipolar disorder. In the remission period, peak power values of PSD distinguish cases with psychotic findings from cases without psychotic findings when they were manic.

  9. Comparative analysis of normalised difference spectral indices derived from MODIS for detecting surface water in flooded rice cropping systems.

    PubMed

    Boschetti, Mirco; Nutini, Francesco; Manfron, Giacinto; Brivio, Pietro Alessandro; Nelson, Andrew

    2014-01-01

    Identifying managed flooding in paddy fields is commonly used in remote sensing to detect rice. Such flooding, followed by rapid vegetation growth, is a reliable indicator to discriminate rice. Spectral indices (SIs) are often used to perform this task. However, little work has been done on determining which spectral combination in the form of Normalised Difference Spectral Indices (NDSIs) is most appropriate for surface water detection or which thresholds are most robust to separate water from other surfaces in operational contexts. To address this, we conducted analyses on satellite and field spectral data from an agronomic experiment as well as on real farming situations with different soil and plant conditions. Firstly, we review and select NDSIs proposed in the literature, including a new combination of visible and shortwave infrared bands. Secondly, we analyse spectroradiometric field data and satellite data to evaluate mixed pixel effects. Thirdly, we analyse MODIS data and Landsat data at four sites in Europe and Asia to assess NDSI performance in real-world conditions. Finally, we test the performance of the NDSIs on MODIS temporal profiles in the four sites. We also compared the NDSIs against a combined index previously used for agronomic flood detection. Analyses suggest that NDSIs using MODIS bands 4 and 7, 1 and 7, 4 and 6 or 1 and 6 perform best. A common threshold for each NDSI across all sites was more appropriate than locally adaptive thresholds. In general, NDSIs that use band 7 have a negligible increase in Commission Error over those that use band 6 but are more sensitive to water presence in mixed land cover conditions typical of moderate spatial resolution analyses. The best performing NDSI is comparable to the combined index but with less variability in performance across sites, suggesting a more succinct and robust flood detection method.

  10. Comparative Analysis of Normalised Difference Spectral Indices Derived from MODIS for Detecting Surface Water in Flooded Rice Cropping Systems

    PubMed Central

    Boschetti, Mirco; Nutini, Francesco; Manfron, Giacinto; Brivio, Pietro Alessandro; Nelson, Andrew

    2014-01-01

    Identifying managed flooding in paddy fields is commonly used in remote sensing to detect rice. Such flooding, followed by rapid vegetation growth, is a reliable indicator to discriminate rice. Spectral indices (SIs) are often used to perform this task. However, little work has been done on determining which spectral combination in the form of Normalised Difference Spectral Indices (NDSIs) is most appropriate for surface water detection or which thresholds are most robust to separate water from other surfaces in operational contexts. To address this, we conducted analyses on satellite and field spectral data from an agronomic experiment as well as on real farming situations with different soil and plant conditions. Firstly, we review and select NDSIs proposed in the literature, including a new combination of visible and shortwave infrared bands. Secondly, we analyse spectroradiometric field data and satellite data to evaluate mixed pixel effects. Thirdly, we analyse MODIS data and Landsat data at four sites in Europe and Asia to assess NDSI performance in real-world conditions. Finally, we test the performance of the NDSIs on MODIS temporal profiles in the four sites. We also compared the NDSIs against a combined index previously used for agronomic flood detection. Analyses suggest that NDSIs using MODIS bands 4 and 7, 1 and 7, 4 and 6 or 1 and 6 perform best. A common threshold for each NDSI across all sites was more appropriate than locally adaptive thresholds. In general, NDSIs that use band 7 have a negligible increase in Commission Error over those that use band 6 but are more sensitive to water presence in mixed land cover conditions typical of moderate spatial resolution analyses. The best performing NDSI is comparable to the combined index but with less variability in performance across sites, suggesting a more succinct and robust flood detection method. PMID:24586381

  11. Spectral Barcoding of Quantum Dots: Deciphering Structural Motifs from the Excitonic Spectra

    SciTech Connect

    Mlinar, V.; Zunger, A.

    2009-01-01

    Self-assembled semiconductor quantum dots (QDs) show in high-resolution single-dot spectra a multitude of sharp lines, resembling a barcode, due to various neutral and charged exciton complexes. Here we propose the 'spectral barcoding' method that deciphers structural motifs of dots by using such barcode as input to an artificial-intelligence learning system. Thus, we invert the common practice of deducing spectra from structure by deducing structure from spectra. This approach (i) lays the foundation for building a much needed structure-spectra understanding for large nanostructures and (ii) can guide future design of desired optical features of QDs by controlling during growth only those structural motifs that decide given optical features.

  12. Spectral characteristics of distributed feedback semiconductor laser and their improvements by corrugation-pitch-modulated structure

    NASA Astrophysics Data System (ADS)

    Okai, Makoto

    1994-01-01

    This paper presents a review of a theoretical analysis problems that occur with single-mode lasers, and a novel laser structure for superstable single-mode operation. Also presented is a new grating-fabrication technique termed photo-mask self-interference, to fabricate corrugation-pitch-modulated (CPM) structures, for enhancing the stability of the longitudinal single-mode operation in distributed feedback lasers (DFB). It is seen that the CPM-DFB laser developed for coherent transmission systems displays the narrowest spectral linewidth (56 kHz) reported so far for a semiconductor.

  13. Crustacean neuropeptides: structures, functions and comparative aspects.

    PubMed

    Keller, R

    1992-05-15

    In this article, an attempt is made to review the presently known, completely identified crustacean neuropeptides with regard to structure, function and distribution. Probably the most important progress has been made in the elucidation of a novel family of large peptides from the X-organ-sinus gland system which includes crustacean hyperglycemic hormone (CHH), putative molt-inhibiting hormone (MIH) and vitellogenesis (= gonad)-inhibiting hormone (VIH). These peptides have so far only been found in crustaceans. Renewed interest in the neurohemal pericardial organs has led to the identification of a number of cardioactive/myotropic neuropeptides, some of them unique to crustaceans. Important contributions have been made by immunocytochemical mapping of peptidergic neurons in the nervous system, which has provided evidence for a multiple role of several neuropeptides as neurohormones on the one hand and as local transmitters or modulators on the other. This has been corroborated by physiological studies. The long-known chromatophore-regulating hormones, red pigment concentrating hormone (RPCH) and pigment-dispending hormone (PDH), have been placed in a broader perspective by the demonstration of an additional role as local neuromodulators. The scope of crustacean neuropeptide research has thus been broadened considerably during the last years.

  14. Structural, spectral-luminescent, and lasing properties of nanostructured Tm : CaF{sub 2} ceramics

    SciTech Connect

    Ryabochkina, P A; Lyapin, A A; Osiko, Vyacheslav V; Fedorov, Pavel P; Ushakov, S N; Kruglova, M V; Sakharov, N V; Garibin, E A; Gusev, P E; Krutov, M A

    2012-09-30

    The structure and the spectral-luminescent properties of CaF{sub 2} - TmF{sub 3} fluoride ceramics and single crystals are studied. AFM investigations revealed a layered nanostructure of grains, which was not observed in reference samples of single crystals. It is found that the spectral-luminescent properties of CaF{sub 2} - TmF{sub 3} ceramics and single crystals are similar. Lasing at the {sup 3}F{sub 4} {yields} {sup 3}H{sub 6} transition of Tm{sup 3+} ions in CaF{sub 2} - TmF{sub 3} ceramics (wavelength 1898 nm) under diode pimping is obtained for the first time. (laser applications and other topics in quantum electronics)

  15. Spectral and structural studies of the anti-cancer drug Flutamide by density functional theoretical method.

    PubMed

    Mariappan, G; Sundaraganesan, N

    2014-01-03

    A comprehensive screening of the more recent DFT theoretical approach to structural analysis is presented in this section of theoretical structural analysis. The chemical name of 2-methyl-N-[4-nitro-3-(trifluoromethyl)phenyl]-propanamide is usually called as Flutamide (In the present study it is abbreviated as FLT) and is an important and efficacious drug in the treatment of anti-cancer resistant. The molecular geometry, vibrational spectra, electronic and NMR spectral interpretation of Flutamide have been studied with the aid of density functional theory method (DFT). The vibrational assignments of the normal modes were performed on the basis of the PED calculations using the VEDA 4 program. Comparison of computational results with X-ray diffraction results of Flutamide allowed the evaluation of structure predictions and confirmed B3LYP/6-31G(d,p) as accurate for structure determination. Application of scaling factors for IR and Raman frequency predictions showed good agreement with experimental values. This is supported the assignment of the major contributors of the vibration modes of the title compound. Stability of the molecule arising from hyperconjugative interactions leading to its bioactivity, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. NMR chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. The comparison of measured FTIR, FT-Raman, and UV-Visible data to calculated values allowed assignment of major spectral features of the title molecule. Besides, Frontier molecular orbital analyze was also investigated using theoretical calculations.

  16. Spectral and structural studies of the anti-cancer drug Flutamide by density functional theoretical method

    NASA Astrophysics Data System (ADS)

    Mariappan, G.; Sundaraganesan, N.

    2014-01-01

    A comprehensive screening of the more recent DFT theoretical approach to structural analysis is presented in this section of theoretical structural analysis. The chemical name of 2-methyl-N-[4-nitro-3-(trifluoromethyl)phenyl]-propanamide is usually called as Flutamide (In the present study it is abbreviated as FLT) and is an important and efficacious drug in the treatment of anti-cancer resistant. The molecular geometry, vibrational spectra, electronic and NMR spectral interpretation of Flutamide have been studied with the aid of density functional theory method (DFT). The vibrational assignments of the normal modes were performed on the basis of the PED calculations using the VEDA 4 program. Comparison of computational results with X-ray diffraction results of Flutamide allowed the evaluation of structure predictions and confirmed B3LYP/6-31G(d,p) as accurate for structure determination. Application of scaling factors for IR and Raman frequency predictions showed good agreement with experimental values. This is supported the assignment of the major contributors of the vibration modes of the title compound. Stability of the molecule arising from hyperconjugative interactions leading to its bioactivity, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. NMR chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. The comparison of measured FTIR, FT-Raman, and UV-Visible data to calculated values allowed assignment of major spectral features of the title molecule. Besides, Frontier molecular orbital analyze was also investigated using theoretical calculations.

  17. Mixed-Grass Prairie Canopy Structure and Spectral Reflectance Vary with Topographic Position

    NASA Astrophysics Data System (ADS)

    Phillips, Rebecca L.; Ngugi, Moffatt K.; Hendrickson, John; Smith, Aaron; West, Mark

    2012-11-01

    Managers of the nearly 0.5 million ha of public lands in North and South Dakota, USA rely heavily on manual measurements of canopy height in autumn to ensure conservation of grassland structure for wildlife and forage for livestock. However, more comprehensive assessment of vegetation structure could be achieved for mixed-grass prairie by integrating field survey, topographic position (summit, mid and toeslope) and spectral reflectance data. Thus, we examined the variation of mixed-grass prairie structural attributes (canopy leaf area, standing crop mass, canopy height, nitrogen, and water content) and spectral vegetation indices (VIs) with variation in topographic position at the Grand River National Grassland (GRNG), South Dakota. We conducted the study on a 36,000-ha herbaceous area within the GRNG, where randomly selected plots (1 km2 in size) were geolocated and included summit, mid and toeslope positions. We tested for effects of topographic position on measured vegetation attributes and VIs calculated from Landsat TM and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data collected in July 2010. Leaf area, standing crop mass, canopy height, nitrogen, and water content were lower at summits than at toeslopes. The simple ratio of Landsat Band 7/Band 1 (SR71) was the VI most highly correlated with canopy standing crop and height at plot and landscape scales. Results suggest field and remote sensing-based grassland assessment techniques could more comprehensively target low structure areas at minimal expense by layering modeled imagery over a landscape stratified into topographic position groups.

  18. Noninvasive in vivo structural and vascular imaging of human oral tissues with spectral domain optical coherence tomography

    PubMed Central

    Davoudi, Bahar; Lindenmaier, Andras; Standish, Beau A.; Allo, Ghassan; Bizheva, Kostadinka; Vitkin, Alex

    2012-01-01

    A spectral domain optical coherence tomography (SD-OCT) system and an oral imaging probe have been developed to visualize the microstructural morphology and microvasculature in the human oral cavity. Structural OCT images of ex vivo pig oral tissues with the histology of the same sites were acquired and compared for correlations. Structural in vivo OCT images of healthy human tissue as well as a pathologic site (ulcer) were obtained and analyzed based on the results of the ex vivo pig study, drawing on the similarity between human and swine oral tissues. In vivo Doppler and speckle variance OCT images of the oral cavity in human volunteers were also acquired, to demonstrate the feasibility of microvascular imaging of healthy and pathologic (scar) oral tissue. PMID:22567578

  19. Structural dynamics of hydrogen bonded methanol oligomers: Vibrational transient hole burning studies of spectral diffusion

    NASA Astrophysics Data System (ADS)

    Piletic, I. R.; Gaffney, K. J.; Fayer, M. D.

    2003-07-01

    Frequency resolved pump-probe experiments have been conducted on the deuterated hydroxyl stretch of methanol-d in a solution containing 0.8% methanol-d/23% methanol-h in carbon tetrachloride. Methanol-d molecules that both donate and receive hydrogen bonds have an inhomogeneously broadened hydroxyl stretch absorption line centered at 2487 cm-1. With a laser tuned to 2513 cm-1, the high-frequency side of the absorption spectrum is excited. The equilibration of the excited state peak and the ground-state hole results in the time-dependent shift in the frequency of the signal, which is used to monitor the dynamics of spectral diffusion. Model calculations were conducted to address the influence of spectral diffusion in the ground and excited states on the experimental observables when the vibrational lifetime is comparable to the spectral diffusion time. The model calculations illustrate the influence on the signal of absorbers in the ground state that have relaxed from the excited state. This aspect of the problem has not been addressed in previous descriptions of frequency resolved pump-probe spectroscopy. The calculations were used to fit the time-dependent peak maximum, resulting in a bi-exponential frequency-frequency correlation function, with a fast time constant of roughly 0.1 ps and a slower time constant of 1.6±0.3 ps. The observed dynamics have been compared with the predictions of dielectric continuum theory. The inability of a simple dielectric continuum theory to predict the observed spectral diffusion dynamics suggests that these dynamics do not result from the long-wavelength, collective orientational relaxation of the solvent. Instead the dynamics are attributed to fluctuations in the local hydrogen bond network, which is consistent with recent molecular-dynamics simulations of vibrational transient hole burning in water.

  20. Rosetta/VIRTIS-M spectral data: Comet 67P/CG compared to other primitive small bodies.

    NASA Astrophysics Data System (ADS)

    De Sanctis, M. C.; Capaccioni, F.; Filacchione, G.; Erard, S.; Tosi, F.; Ciarniello, M.; Raponi, A.; Piccioni, G.; Leyrat, C.; Bockelée-Morvan, D.; Drossart, P.; Fornasier, S.

    2014-12-01

    VIRTIS-M, the Visible InfraRed Thermal Imaging Spectrometer, onboard the Rosetta Mission orbiter (Coradini et al., 2007) acquired data of the comet 67P/Churyumov-Gerasimenko in the 0.25-5.1 µm spectral range. The initial data, obtained during the first mission phases to the comet, allow us to derive albedo and global spectral properties of the comet nucleus as well as spectra of different areas on the nucleus. The characterization of cometary nuclei surfaces and their comparison with those of related populations such as extinct comet candidates, Centaurs, near-Earth asteroids (NEAs), trans-Neptunian objects (TNOs), and primitive asteroids is critical to understanding the origin and evolution of small solar system bodies. The acquired VIRTIS data are used to compare the global spectral properties of comet 67P/CG to published spectra of other cometary nuclei observed from ground or visited by space mission. Moreover, the spectra of 67P/Churyumov-Gerasimenko are also compared to those of primitive asteroids and centaurs. The comparison can give us clues on the possible common formation and evolutionary environment for primitive asteroids, centaurs and Jupiter-family comets. Authors acknowledge the funding from Italian and French Space Agencies. References: Coradini, A., Capaccioni, F., Drossart, P., Arnold, G., Ammannito, E., Angrilli, F., Barucci, A., Bellucci, G., Benkhoff, J., Bianchini, G., Bibring, J. P., Blecka, M., Bockelee-Morvan, D., Capria, M. T., Carlson, R., Carsenty, U., Cerroni, P., Colangeli, L., Combes, M., Combi, M., Crovisier, J., De Sanctis, M. C., Encrenaz, E. T., Erard, S., Federico, C., Filacchione, G., Fink, U., Fonti, S., Formisano, V., Ip, W. H., Jaumann, R., Kuehrt, E., Langevin, Y., Magni, G., McCord, T., Mennella, V., Mottola, S., Neukum, G., Palumbo, P., Piccioni, G., Rauer, H., Saggin, B., Schmitt, B., Tiphene, D., Tozzi, G., Space Science Reviews, Volume 128, Issue 1-4, 529-559, 2007.

  1. The use of antioptimization to compare alternative structural models

    NASA Technical Reports Server (NTRS)

    Gangadharan, S. N.; Nikolaidis, E.; Lee, K.; Haftka, R. T.

    1993-01-01

    Structural models are usually tested by comparing their response with that of a reference structure (an actual structure or a more refined model) to a limited number of arbitrary loads. This test is not always reliable because the loads are arbitrary. An antioptimization-based method is proposed to test structural models. This method compares a structural model with a reference model or an actual structure under the worst loading case that maximizes the error in the model. Specifically, the method identifies the loading case that maximizes the difference between the responses of two models of the same structure using optimization. This method can be used to design experiments in order to validate a structural model. It can also be applied to identify damage in a structure by determining the load that maximizes the difference in the behavior of the damaged and the intact structure. The proposed method is illustrated by applying it to a plate and an automotive structure.

  2. Spectral element method for band-structure calculations of 3D phononic crystals

    NASA Astrophysics Data System (ADS)

    Shi, Linlin; Liu, Na; Zhou, Jianyang; Zhou, Yuanguo; Wang, Jiamin; Huo Liu, Qing

    2016-11-01

    The spectral element method (SEM) is a special kind of high-order finite element method (FEM) which combines the flexibility of a finite element method with the accuracy of a spectral method. In contrast to the traditional FEM, the SEM exhibits advantages in the high-order accuracy as the error decreases exponentially with the increase of interpolation degree by employing the Gauss-Lobatto-Legendre (GLL) polynomials as basis functions. In this study, the spectral element method is developed for the first time for the determination of band structures of 3D isotropic/anisotropic phononic crystals (PCs). Based on the Bloch theorem, we present a novel, intuitive discretization formulation for Navier equation in the SEM scheme for periodic media. By virtue of using the orthogonal Legendre polynomials, the generalized eigenvalue problem is converted to a regular one in our SEM implementation to improve the efficiency. Besides, according to the specific geometry structure, 8-node and 27-node hexahedral elements as well as an analytic mesh have been used to accurately capture curved PC models in our SEM scheme. To verify its accuracy and efficiency, this study analyses the phononic-crystal plates with square and triangular lattice arrangements, and the 3D cubic phononic crystals consisting of simple cubic (SC), bulk central cubic (BCC) and faced central cubic (FCC) lattices with isotropic or anisotropic scatters. All the numerical results considered demonstrate that SEM is superior to the conventional FEM and can be an efficient alternative method for accurate determination of band structures of 3D phononic crystals.

  3. Infrared spectral evidence and DFT calculations of hydrogen-bonding and molecular structures of acetogenins

    NASA Astrophysics Data System (ADS)

    Afonso, Sabrina; Silva, Fabiano B.; Silva, Arnaldo F.; Scarminio, Ieda S.; Bruns, Roy E.

    2017-02-01

    FTIR spectra have been measured for 31 different five component - simplex centroid design solvent mixture extracts of shaded and sun-exposed Annonaceous leaves harvested in all four seasons. The spectral frequencies are characteristic of anonnaceous acetogenins known to be a major component of these leaves. Osbnd H stretching spectral bands in the 3100-3600 cm-1 region provide evidence of notable intensity changes for the shaded and sun-exposed leaves. Chemometric principal component analysis involving 264 spectra show that shaded samples tend to have more intense Osbnd H stretching bands than those grown in the sun. B3LYP density functional calculations indicate significant Osbnd H stretching band changes in this region owing to hydrogen bond formation. Weak Osbnd H intensity enhancements, around 40 km mol-1, occur when an Osbnd H group forms a hydrogen bond with the oxygen atom of an adjacent tetrahydrofuran ring oxygen atom. Much more intense enhancements, 400-500 km mol-1, are predicted to occur for acetogenins with two tetrahydrofuran rings for which the Osbnd H group hydrogen bonds with its fartherest removed tetrahydrofuran ring oxygen. Whereas weak or moderate H-bond stretching intensities are obtained for acetogenins with slightly bent carbon chain structures the strongest hydrogen bond intensities are calculated for molecules with a 45° V-type backbone structure. These important structural modifications as well as significant changes in bond lengths and angles owing to hydrogen bonding are detailed.

  4. All optical parallel-to-serial conversion by modified spectral holography structure

    NASA Astrophysics Data System (ADS)

    Yan, X.; Cao, L.; Dai, Y.; Yang, X.; Bai, L.; Ma, G.

    2012-07-01

    In this paper, a modified spectral holography structure is demonstrated. Combining the direct space-to-time pulse shaping theory with the modified structure, we can convert a spatial domain x- y image into a y- t image, where one spatial dimension is now transformed into the time domain. Thus we realize the space-to-time or parallel-to-serial conversion. As an example, we generate the temporal equivalent of letter "A", where each pixel of the image is now represented by a short optical pulse. As a possible application of our scheme, we demonstrate the generation of trains of a femtosecond pulse sequence by our structure. The results of the paper can be applied in ultrashort pulse shaping, ultrafast communication and other relevant areas.

  5. Spectral properties of a double-quantum-dot structure: A causal Green's function approach

    NASA Astrophysics Data System (ADS)

    You, J. Q.; Zheng, Hou-Zhi

    1999-09-01

    Spectral properties of a double quantum dot (QD) structure are studied by a causal Green's function (GF) approach. The double QD system is modeled by an Anderson-type Hamiltonian in which both the intra- and interdot Coulomb interactions are taken into account. The GF's are derived by an equation-of-motion method and the real-space renormalization-group technique. The numerical results show that the average occupation number of electrons in the QD exhibits staircase features and the local density of states depends appreciably on the electron occupation of the dot.

  6. Comparative spectral analysis of commercial fuel-ethanol blends using a low-cost prototype FT-Raman spectrometer

    NASA Astrophysics Data System (ADS)

    Ortega Clavero, Valentin; Weber, Andreas; Schröder, Werner; Meyrueis, Patrick; Javahiraly, Nicolas

    2012-06-01

    The use of bio-fuels and fuel blends, specially in automotive industry, has been increasing substantially in recent years due to market prices and trends on sustainable development policies. Different spectral analysis techniques for quality control, production, purity, and counterfeit detection have been reported as non-invasive, fast, and price accessible. Raman spectra from three different commercial binary E10 fuel-ethanol blends has been obtained by using a low-cost Fourier-Transform Raman spectrometer (FT-Raman). Qualitative comparison between the commercial fuel blends and a laboratory-prepared fuel blend have been performed. The characteristic Raman lines from some additives contained in the commercial gasoline have been also observed. The spectral information is presented in the range of 0 cm-1 to 3500 cm-1 with a resolution of 1.66 cm-1. These Raman spectra shows reduced frequency deviation (less than 0.4 cm-1 when compared to standard Raman spectra from cyclohexane and toluene without compensation for instrumental response). Higher resolution values are possible, since the greater optical path lengths of the FT-Raman are achievable before the instrumental physical effects appear. The robust and highly flexible FT-Raman prototype proposed for the spectral analysis, consisting mainly of a Michelson interferometer and a self-designed photon counter, is able to deliver high resolution and precise Raman spectra with no additional complex hardware or software control. The mechanical and thermal disturbances affecting the FT-Raman system are mathematically compensated by extracting the optical path information from the generated interference pattern of a λ=632.8 nm Helium-Neon laser (HeNe laser), which is used at the spectrum evaluation.

  7. VLT FORS2 comparative transmission spectral survey of clear and cloudy exoplanet atmospheres

    NASA Astrophysics Data System (ADS)

    Nikolov, Nikolay; Sing, David K.; Gibson, Neale; Fortney, Jonathan J.; Evans, Tom M.; Barstow, Joanna; Kataria, Tiffany; Wilson, Paul

    2017-01-01

    Thousands of transiting exoplanets are known today but not many have been studied in transmission. While observations with the Hubble Space Telescope (HST) have started to reveal a diversity of atmosphere types, drawing robust conclusions about the underlying population is hampered by the small sample size. This can be greatly aided by ground-based telescopes, equipped with multi-object spectrographs by their unprecedented access to the abundance of fainter systems that HST cannot observe. We have initiated a ground-based, multi-object transmission spectroscopy of a handful of hot gas-giants, covering the wavelength range 360-850nm, using the recently upgraded FOcal Reducer and Spectrograph (FORS2) mounted on the Very Large Telescope (VLT). These exoplanets were selected for a comparative follow-up as their transmission spectra showed evidence for alkali metal absorption, based on the results of HST observations. Here we will discuss first results from the program, demonstrating an excellent agreement between the transmission spectra measured from VLT and HST and detections of Na and K absorption and scattering by clouds/hazes in the atmospheres of several exoplanets. More details will be discussed on the narrow alkali features obtained with FORS2 at higher resolution, revealing its high potential in obtaining optical transmission spectra, which can greatly aid comparative exoplanet studies.

  8. Comparative statistical and spectral studies of seismic and non-seismic sub-ionospheric VLF anomalies

    NASA Astrophysics Data System (ADS)

    Wolbang, Daniel; Biernat, Helfried; Schwingenschuh, Konrad; Eichelberger, Hans; Prattes, Gustav; Besser, Bruno; Boudjada, Mohammed Y.; Rozhnoi, Alexander; Solovieva, Maria; Biagi, Pier Francesco; Friedrich, Martin

    2013-04-01

    We present a comparative study of seismic and non-seismic sub-ionospheric VLF anomalies. Our method is based on parameter variations of the sub-ionospheric VLF waveguide formed by the surface and the lower ionosphere. The used radio links working in the frequency range between 10 and 50 kHz, the receivers are part of the European and Russian networks. Various authors investigated the lithopsheric-atmospheric-ionospheric coupling and predicted the lowering of the ionosphere over earthquake preparation zones [1]. The received nighttime signal of a sub-ionospheric waveguide depends strongly on the height of the ionospheric E-layer, typically 80 to 85 km. This height is characterized by a typical gradient of the electron density near the atmospheric-ionospheric boundary [2]. In the last years it has been turned out that one of the major issues of sub-ionospheric seismo-electromagnetic VLF studies are the non-seismic influences on the links, which have to be carefully characterized. Among others this could be traveling ionospheric disturbances, geomagnetic storms as well as electron precipitation. Our emphasis is on the analysis of daily, monthly and annual variations of the VLF amplitude. To improve the statistics we investigate the behavior and typical variations of the VLF amplitude and phase over a period of more than 2 years. One important parameter considered is the rate how often the fluctuations are falling below a significant level derived from a mean value. The temporal variations and the amplitudes of these depressions are studied for several years for sub-ionospheric VLF radio links with the receivers in Graz and Kamchatka. In order to study the difference between seismic and non-seismic turbulences in the lower ionosphere a power spectrum analysis of the received signal is performed too. We are especially interested in variations T>6 min which are typical for atmospheric gravity waves causing the lithospheric-atmospheric-ionospheric coupling [3]. All

  9. The impact of spatial and spectral frequencies in structured light imaging of thick tissues

    NASA Astrophysics Data System (ADS)

    Weber, Jessie Ruth

    This research focuses on development of structured light imaging (SLI), a new optical imaging technique based on spatial frequency domain modulation. The goal of this method is to quantitatively measure and map tissue optical properties, absorption and scattering, to determine tissue biochemical structure and composition. The work presented here extends the technology's spatial and spectral frequency impact. First, to expand the depth sectioning capability of spatial frequency modulation, a layered tissue model was developed, validated and shown to accurately recover in vivo parameters in skin (epidermis and dermis), effectively filtering out signal from the underlying subcutaneous tissue. Next, to expand the impact of spectral frequency information, the SLI system was combined with a Computed Tomography Imaging Spectrometer (CTIS), which eliminates the need to scan through wavelengths when gathering multispectral information. A single SLI-CTIS measurement gathers 36 absorption maps and 36 scattering maps, with a resulting measurement speed ˜30 times faster than the liquid crystal tunable filter method currently employed in multispectral SLI systems. The multispectral information can be used to determine the concentrations of multiple tissue chromophores and the relative density of the tissue. This is immediately useful for monitoring the brain for signs of trauma, including monitoring of oxygen delivery across the brain, mapping of hemoglobin concentration to detect hemorrhage, mapping of water content to monitor edema, and mapping of tissue density to monitor swelling. A simple in vivo brain injury example is presented to demonstrate recovery of these parameters. Finally, to demonstrate the spatial, spectral and temporal resolution of the SLI-CTIS system, measurements were performed on in vivo mouse brain during seizure with electroencephalography (EEG) confirmation.

  10. Comparative Analysis of Alternative Spectral Bands of CO2 and O2 for the Sensing of CO2 Mixing Ratios

    NASA Technical Reports Server (NTRS)

    Pliutau, Denis; Prasad, Narasimha S.

    2013-01-01

    We performed comparative studies to establish favorable spectral regions and measurement wavelength combinations in alternative bands of CO2 and O2, for the sensing of CO2 mixing ratios (XCO2) in missions such as ASCENDS. The analysis employed several simulation approaches including separate layers calculations based on pre-analyzed atmospheric data from the modern-era retrospective analysis for research and applications (MERRA), and the line-byline radiative transfer model (LBLRTM) to obtain achievable accuracy estimates as a function of altitude and for the total path over an annual span of variations in atmospheric parameters. Separate layer error estimates also allowed investigation of the uncertainties in the weighting functions at varying altitudes and atmospheric conditions. The parameters influencing the measurement accuracy were analyzed independently and included temperature sensitivity, water vapor interferences, selection of favorable weighting functions, excitations wavelength stabilities and other factors. The results were used to identify favorable spectral regions and combinations of on / off line wavelengths leading to reductions in interferences and the improved total accuracy.

  11. Ultraviolet spectral distribution and erythema-weighted irradiance from indoor tanning devices compared with solar radiation exposures.

    PubMed

    Sola, Yolanda; Baeza, David; Gómez, Miguel; Lorente, Jerónimo

    2016-08-01

    Concern regarding the impact of indoor tanning devices on human health has led to different regulations and recommendations, which set limits on erythema-weighted irradiance. Here, we analyze spectral emissions from 52 tanning devices in Spanish facilities and compare them with surface solar irradiance for different solar zenith angles. Whereas most of the devices emitted less UV-B radiation than the midday summer sun, the unweighted UV-A irradiance was 2-6 times higher than solar radiation. Moreover, the spectral distributions of indoor devices were completely different from that of solar radiation, differing in one order of magnitude at some UV-A wavelengths, depending on the lamp characteristics. In 21% of the devices tested, the erythema-weighted irradiance exceeded 0.3Wm(-2): the limit fixed by the European standard and the Spanish regulation. Moreover, 29% of the devices fall within the UV type 4 classification, for which medical advice is required. The high variability in erythema-weighted irradiance results in a wide range of exposure times to reach 1 standard erythemal dose (SED: 100Jm(-2)), with 62% of devices requiring exposures of <10min to reach 1 SED. Nevertheless, the unweighted UV-A dose during this time period would be from 1.4 to 10.3 times more than the solar UV-A dose.

  12. A comprehensive comparison of comparative RNA structure prediction approaches

    PubMed Central

    Gardner, Paul P; Giegerich, Robert

    2004-01-01

    Background An increasing number of researchers have released novel RNA structure analysis and prediction algorithms for comparative approaches to structure prediction. Yet, independent benchmarking of these algorithms is rarely performed as is now common practice for protein-folding, gene-finding and multiple-sequence-alignment algorithms. Results Here we evaluate a number of RNA folding algorithms using reliable RNA data-sets and compare their relative performance. Conclusions We conclude that comparative data can enhance structure prediction but structure-prediction-algorithms vary widely in terms of both sensitivity and selectivity across different lengths and homologies. Furthermore, we outline some directions for future research. PMID:15458580

  13. OT1_dweedman_1: Comparing [CII] 158 micron Luminosities to Spectral Properties of Luminous Starburst Galaxies and AGN

    NASA Astrophysics Data System (ADS)

    Weedman, D.

    2010-07-01

    Herschel PACS spectroscopy of the [CII] emission line at 158 microns is proposed for a carefully selected sample of 123 sources that already have complete low and high resolution mid-infrared spectra between 5 microns and 35 microns from the Spitzer Infrared Spectrograph, and which also have spectral energy distributions (SEDs) from IRAS and Akari photometry. [CII] 158 um is the strongest far-infrared emission line and therefore crucial to compare with other features in luminous, dusty galaxies. Sources have 0.004 < z < 0.34 and 43.0 < log L(IR) < 46.8 (erg per sec) and cover the full range of starburst galaxy and AGN classifications. Obtaining these [CII] line fluxes with PACS will allow: 1. determining how precisely [CII] luminosity measures star formation rate by comparing to PAH features and emission lines that arise in starburst galaxies; 2. determining how [CII] luminosity and equivalent width changes with starburst/AGN fraction, by comparing with strength and equivalent width of PAH and [NeII] emission arising from starbursts, and with strength of high ionization lines [NeV] and [OIV] and silicate absorption or emission arising from AGN; 3. determining how [CII] luminosity and equivalent width changes with dust temperature and bolometric luminosity, as derived from spectral energy distributions, and whether this depends on the starburst/AGN fraction. These determinations will allow interpretation of high redshift sources for which the only available diagnostics are the luminosity and equivalent width of the [CII] line and the far-infrared rest-frame SED. The total observing program requires 20.2 hours of Herschel observing time.

  14. Tools for comparative protein structure modeling and analysis.

    PubMed

    Eswar, Narayanan; John, Bino; Mirkovic, Nebojsa; Fiser, Andras; Ilyin, Valentin A; Pieper, Ursula; Stuart, Ashley C; Marti-Renom, Marc A; Madhusudhan, M S; Yerkovich, Bozidar; Sali, Andrej

    2003-07-01

    The following resources for comparative protein structure modeling and analysis are described (http://salilab.org): MODELLER, a program for comparative modeling by satisfaction of spatial restraints; MODWEB, a web server for automated comparative modeling that relies on PSI-BLAST, IMPALA and MODELLER; MODLOOP, a web server for automated loop modeling that relies on MODELLER; MOULDER, a CPU intensive protocol of MODWEB for building comparative models based on distant known structures; MODBASE, a comprehensive database of annotated comparative models for all sequences detectably related to a known structure; MODVIEW, a Netscape plugin for Linux that integrates viewing of multiple sequences and structures; and SNPWEB, a web server for structure-based prediction of the functional impact of a single amino acid substitution.

  15. Study on structural and spectral properties of isobavachalcone and 4-hydroxyderricin by computational method

    NASA Astrophysics Data System (ADS)

    Rong, Yuzhi; Wu, Jinhong; Liu, Xing; Zhao, Bo; Wang, Zhengwu

    Isobavachalcone and 4-hydroxyderricin, two major chalcone constituents isolated from the roots of Angelica keiskei KOIDZUMI, exhibit numerous biological activities. Quantum chemical methods have been employed to investigate their structural and spectral properties. The ground state structures were optimized using density functional B3LYP method with 6-311G (d, p) basis set in both gas and solvent phases. Based on the optimized geometries, the harmonic vibrational frequency, the 1H and 13C nuclear magnetic resonance (NMR) chemical shift using the GIAO method were calculated at the same level of theory, with the aim of verifying the experimental values. Results reveal that B3LYP has been a good method to study their vibrational spectroscopic and NMR spectral properties of the two chalcones. The electronic absorption spectra were calculated using the time-dependent density functional theory (TDDFT) method. The solvent polarity effects were considered and calculated using the polarizable continuum model (PCM). Results also show that substitutions of different electron donating groups can alter the absorption properties and shift the spectra to a higher wavelength region.

  16. Spectral element method for band structures of two-dimensional anisotropic photonic crystals.

    PubMed

    Luo, Ma; Liu, Qing Huo; Li, Zhibing

    2009-02-01

    A spectral element method (SEM) is proposed for the accurate calculation of band structures of two-dimensional anisotropic photonic crystals. It uses Gauss-Lobatto-Legendre polynomials as the basis functions in the finite-element framework with curvilinear quadrilateral elements. Coordination mapping is introduced to make the curved quadrilateral elements conformal with the problem geometry. Mixed order basis functions are used in the vector SEM for full vector calculation. The numerical convergence speed of the method is investigated with both square and triangular lattices, and with isotropic and in-plane anisotropic media. It is shown that this method has spectral accuracy, i.e., the numerical error decreases exponentially with the order of basis functions. With only four points per wavelength, the SEM can achieve a numerical error smaller than 0.1%. The full vector calculation method can suppress all spurious modes with nonzero eigenvalues, thus making it easy to filter out real modes. It is thus demonstrated that the SEM is an efficient alternative method for accurate determination of band structures of two-dimensional photonic crystals.

  17. Spectral element method for band structures of two-dimensional anisotropic photonic crystals

    NASA Astrophysics Data System (ADS)

    Luo, Ma; Liu, Qing Huo; Li, Zhibing

    2009-02-01

    A spectral element method (SEM) is proposed for the accurate calculation of band structures of two-dimensional anisotropic photonic crystals. It uses Gauss-Lobatto-Legendre polynomials as the basis functions in the finite-element framework with curvilinear quadrilateral elements. Coordination mapping is introduced to make the curved quadrilateral elements conformal with the problem geometry. Mixed order basis functions are used in the vector SEM for full vector calculation. The numerical convergence speed of the method is investigated with both square and triangular lattices, and with isotropic and in-plane anisotropic media. It is shown that this method has spectral accuracy, i.e., the numerical error decreases exponentially with the order of basis functions. With only four points per wavelength, the SEM can achieve a numerical error smaller than 0.1%. The full vector calculation method can suppress all spurious modes with nonzero eigenvalues, thus making it easy to filter out real modes. It is thus demonstrated that the SEM is an efficient alternative method for accurate determination of band structures of two-dimensional photonic crystals.

  18. Temperature-induced changes in soft tissues analyzed by spectral methods and transient elastography: A comparative study

    NASA Astrophysics Data System (ADS)

    Cortela, G. A.; Benech, N.; Pereira, W. C. A.; Negreira, C.

    2012-05-01

    Some biological tissues, such as skeletal muscle, have regular or quasi-periodic structures. Periodicity of these structures can be investigated by spectral methods based on ultrasonic backscattered signals. These methods estimate the Mean Scatterer Spacing (MSS). In this work we analyzed the MSS dependence with temperature in bovine skeletal muscle tissue samples. Through spectral analysis we found that the relative variation of the MSS, in the temperature range 20 - 48°C was of ~ 2% /°C. For the same sample and under the same experimental conditions, we analyzed the propagation velocity of shear waves by transient elastography. It was determined that the relative variation of shear elastic modulus was ~ 3% /°C in the same temperature range. The repeatability of the results was tested in three tissue samples, with a set of 6 measurements on each. The relative variation is therefore similar for both parameters. Thus, this study shows that both techniques can be used as a method of noninvasive thermometry for small temperature range. In addition we emphasize the conceptual differences between both methods. As temperature changes, MSS estimation varies due to two physical phenomena. An apparent variation in mean spacing is produced because the sound speed is temperature-dependent, while tissue expansion produces a real change. In practice it is difficult to discriminate the weight of each component in the MSS variation. On the other side, transient elastography is less sensitive to thermal expansion. Thus it measures the actual shear wave speed change with temperature. This differentiation between both methods could be used to construct useful thermoelastic models for soft tissues in the future.

  19. What structural length scales can be detected by the spectral variance of a microscope image?

    PubMed

    Cherkezyan, Lusik; Subramanian, Hariharan; Backman, Vadim

    2014-08-01

    A spectroscopic microscope, configured to detect interference spectra of backscattered light in the far zone, quantifies the statistics of refractive-index (RI) distribution via the spectral variance (Σ˜2) of the acquired bright-field image. Its sensitivity to subtle structural changes within weakly scattering, label-free media at subdiffraction scales shows great promise in fields from material science to medical diagnostics. We further investigate the length-scale sensitivity of Σ˜ and reveal that, in theory, it can detect RI fluctuations at any spatial frequency whatsoever. Based on a 5% noise floor, Σ˜ detects scales from ∼22 to 200-700 nm (exact values depend on sample structure and thickness). In an example involving mass-density distribution characteristic of biological cell nuclei, we suggest the level of chromatin organization, which can be quantified via Σ˜.

  20. What structural length scales can be detected by the spectral variance of a microscope image?

    PubMed Central

    Cherkezyan, Lusik; Subramanian, Hariharan; Backman, Vadim

    2015-01-01

    A spectroscopic microscope, configured to detect interference spectra of backscattered light in the far zone, quantifies the statistics of refractive-index (RI) distribution via the spectral variance (Σ̃2) of the acquired bright-field image. Its sensitivity to subtle structural changes within weakly scattering, label-free media at subdiffraction scales shows great promise in fields from material science to medical diagnostics. We further investigate the length-scale sensitivity of Σ̃ and reveal that, in theory, it can detect RI fluctuations at any spatial frequency whatsoever. Based on a 5% noise floor, Σ̃ detects scales from ~22 to 200–700 nm (exact values depend on sample structure and thickness). In an example involving mass-density distribution characteristic of biological cell nuclei, we suggest the level of chromatin organization, which can be quantified via Σ̃. PMID:25078159

  1. Spectral tuning of Amazon parrot feather coloration by psittacofulvin pigments and spongy structures.

    PubMed

    Tinbergen, Jan; Wilts, Bodo D; Stavenga, Doekele G

    2013-12-01

    The feathers of Amazon parrots are brightly coloured. They contain a unique class of pigments, the psittacofulvins, deposited in both barbs and barbules, causing yellow or red coloured feathers. In specific feather areas, spongy nanostructured barb cells exist, reflecting either in the blue or blue-green wavelength range. The blue-green spongy structures are partly enveloped by a blue-absorbing, yellow-colouring pigment acting as a spectral filter, thus yielding a green coloured barb. Applying reflection and transmission spectroscopy, we characterized the Amazons' pigments and spongy structures, and investigated how they contribute to the feather coloration. The reflectance spectra of Amazon feathers are presumably tuned to the sensitivity spectra of the visual photoreceptors.

  2. Heat-induced changes to lipid molecular structure in Vimy flaxseed: Spectral intensity and molecular clustering

    NASA Astrophysics Data System (ADS)

    Yu, Peiqiang; Damiran, Daalkhaijav

    2011-06-01

    Autoclaving was used to manipulate nutrient utilization and availability. The objectives of this study were to characterize any changes of the functional groups mainly associated with lipid structure in flaxseed ( Linum usitatissimum, cv. Vimy), that occurred on a molecular level during the treatment process using infrared Fourier transform molecular spectroscopy. The parameters included lipid CH 3 asymmetric (ca. 2959 cm -1), CH 2 asymmetric (ca. 2928 cm -1), CH 3 symmetric (ca. 2871 cm -1) and CH 2 symmetric (ca. 2954 cm -1) functional groups, lipid carbonyl C dbnd O ester group (ca. 1745 cm -1), lipid unsaturation group (CH attached to C dbnd C) (ca. 3010 cm -1) as well as their ratios. Hierarchical cluster analysis (CLA) and principal components analysis (PCA) were conducted to identify molecular spectral differences. Flaxseed samples were kept raw for the control or autoclaved in batches at 120 °C for 20, 40 or 60 min for treatments 1, 2 and 3, respectively. Molecular spectral analysis of lipid functional group ratios showed a significant decrease ( P < 0.05) in the CH 2 asymmetric to CH 3 asymmetric stretching band peak intensity ratios for the flaxseed. There were linear and quadratic effects ( P < 0.05) of the treatment time from 0, 20, 40 and 60 min on the ratios of the CH 2 asymmetric to CH 3 asymmetric stretching vibration intensity. Autoclaving had no significant effect ( P > 0.05) on lipid carbonyl C dbnd O ester group and lipid unsaturation group (CH attached to C dbnd C) (with average spectral peak area intensities of 138.3 and 68.8 IR intensity units, respectively). Multivariate molecular spectral analyses, CLA and PCA, were unable to make distinctions between the different treatment original spectra at the CH 3 and CH 2 asymmetric and symmetric region (ca. 2988-2790 cm -1). The results indicated that autoclaving had an impact to the mid-infrared molecular spectrum of flaxseed to identify heat-induced changes in lipid conformation. A future study

  3. Fine spectral structures in Jovian decametric radio emission observed by ground-based radio telescope.

    NASA Astrophysics Data System (ADS)

    Panchenko, M.; Brazhenko, A. I.; Shaposhnikov, V. E.; Konovalenko, A. A.; Rucker, H. O.

    2014-04-01

    Jupiter with the largest planetary magnetosphere in the solar system emits intense coherent non-thermal radio emission in a wide frequency range. This emission is a result of a complicated interaction between the dynamic Jovian magnetosphere and energetic particles supplying the free energy from planetary rotation and the interaction between Jupiter and the Galilean moons. Decametric radio emission (DAM) is the strongest component of Jovian radiation observed in a frequency range from few MHz up to 40 MHz. This emission is generated via cyclotron maser mechanism in sources located along Jovian magnetic field lines. Depending on the time scales the Jovian DAMexhibits different complex spectral structures. We present the observations of the Jovian decametric radio emission using the large ground-based radio telescope URAN- 2 (Poltava, Ukraine) operated in the decametric frequency range. This telescope is one of the largest low frequency telescopes in Europe equipped with high performance digital radio spectrometers. The antenna array of URAN-2 consists of 512 crossed dipoles with an effective area of 28 000m2 and beam pattern size of 3.5 x 7 deg. (at 25 MHz). The instrument enables continuous observations of the Jovian radio during long period of times. Jovian DAM was observed continuously since Sep. 2012 (depending on Jupiter visibility) with relatively high time-frequency resolution (4 kHz - 100ms) in the broad frequency range (8-32MHz). We have detected a big amount of the fine spectral structures in the dynamic spectra of DAM such as trains of S-bursts, quasi-continuous narrowband emission, narrow-band splitting events and zebra stripe-like patterns. We analyzed mainly the fine structures associated with non-Io controlled DAM. We discuss how the observed narrowband structures which most probably are related to the propagation of the decametric radiation in the Jupiter's ionosphere can be used to study the plasma parameters in the inner Jovian magnetosphere.

  4. Estimating leaf chlorophyll of barley at different growth stages using spectral indices to reduce soil background and canopy structure effects

    NASA Astrophysics Data System (ADS)

    Yu, Kang; Lenz-Wiedemann, Victoria; Chen, Xinping; Bareth, Georg

    2014-11-01

    Monitoring in situ chlorophyll (Chl) content in agricultural crop leaves is of great importance for stress detection, nutritional state diagnosis, yield prediction and studying the mechanisms of plant and environment interaction. Numerous spectral indices have been developed for chlorophyll estimation from leaf- and canopy-level reflectance. However, in most cases, these indices are negatively affected by variations in canopy structure and soil background. The objective of this study was to develop spectral indices that can reduce the effects of varied canopy structure and growth stages for the estimation of leaf Chl. Hyperspectral reflectance data was obtained through simulation by a radiative transfer model, PROSAIL, and measurements from canopies of barley comprising different cultivars across growth stages using spectroradiometers. We applied a comprehensive band-optimization algorithm to explore five types of spectral indices: reflectance difference (RD), reflectance ratio (RR), normalized reflectance difference (NRD), difference of reflectance ratio (DRR) and ratio of reflectance difference (RRD). Indirectly using the multiple scatter correction (MSC) theory, we hypothesized that RRD can eliminate adverse effects of soil background, canopy structure and multiple scattering. Published indices and multivariate models such as optimum multiple band regression (OMBR), partial least squares regression (PLSR) and support vector machines for regression (SVR) were also employed. Results showed that the ratio of reflectance difference index (RRDI) optimized for simulated data significantly improved the correlation with Chl (R2 = 0.98, p < 0.0001) and was insensitive to LAI variations (1-8), compared to widely used indices such as MCARI/OSAVI (R2 = 0.64, p < 0.0001) and TCARI/OSAVI (R2 = 0.74, p < 0.0001). The RRDI optimized for barley explained 76% of the variation in Chl and outperformed multivariate models. However, the accuracy decreased when employing the indices

  5. Structure-preserving spectral element method in attenuating seismic wave modeling

    NASA Astrophysics Data System (ADS)

    Cai, Wenjun; Zhang, Huai

    2016-04-01

    This work describes the extension of the conformal symplectic method to solve the damped acoustic wave equation and the elastic wave equations in the framework of the spectral element method. The conformal symplectic method is a variation of conventional symplectic methods to treat non-conservative time evolution problems which has superior behaviors in long-time stability and dissipation preservation. To construct the conformal symplectic method, we first reformulate the damped acoustic wave equation and the elastic wave equations in their equivalent conformal multi-symplectic structures, which naturally reveal the intrinsic properties of the original systems, especially, the dissipation laws. We thereafter separate each structures into a conservative Hamiltonian system and a purely dissipative ordinary differential equation system. Based on the splitting methodology, we solve the two subsystems respectively. The dissipative one is cheaply solved by its analytic solution. While for the conservative system, we combine a fourth-order symplectic Nyström method in time and the spectral element method in space to cover the circumstances in realistic geological structures involving complex free-surface topography. The Strang composition method is adopted thereby to concatenate the corresponding two parts of solutions and generate the completed numerical scheme, which is conformal symplectic and can therefore guarantee the numerical stability and dissipation preservation after a large time modeling. Additionally, a relative larger Courant number than that of the traditional Newmark scheme is found in the numerical experiments in conjunction with a spatial sampling of approximately 5 points per wavelength. A benchmark test for the damped acoustic wave equation validates the effectiveness of our proposed method in precisely capturing dissipation rate. The classical Lamb problem is used to demonstrate the ability of modeling Rayleigh-wave propagation. More comprehensive

  6. Laser-induced fluorescence imaging of subsurface tissue structures with a volume holographic spatial-spectral imaging system.

    PubMed

    Luo, Yuan; Gelsinger-Austin, Paul J; Watson, Jonathan M; Barbastathis, George; Barton, Jennifer K; Kostuk, Raymond K

    2008-09-15

    A three-dimensional imaging system incorporating multiplexed holographic gratings to visualize fluorescence tissue structures is presented. Holographic gratings formed in volume recording materials such as a phenanthrenquinone poly(methyl methacrylate) photopolymer have narrowband angular and spectral transmittance filtering properties that enable obtaining spatial-spectral information within an object. We demonstrate this imaging system's ability to obtain multiple depth-resolved fluorescence images simultaneously.

  7. Asteroid surface archaeology: Identification of eroded impact structures by spectral properties on (4) Vesta

    NASA Astrophysics Data System (ADS)

    Hoffmann, M.; Nathues, A.; Schäfer, M.; Schmedemann, N.; Vincent, J.; Russell, C.

    2014-07-01

    excavation of deeper layers of Vesta's crust and gradients of space weathering, the latter showing up also at smaller highly eroded craters. As an example of the third type, a global mosaic demonstrates the relationship of reflectance level and band I depth. A non-uniform distribution appears, with an anomaly emerging from the large crater Albana in one of its sectors. This association seems to be caused by ejected material from this crater. Only the spectral signature has remained to identify the original pattern. The spectral properties appear to be related to an enhanced presence of shocked material [3] and impact glass [4]. Conclusions: Today's non-uniformity of impact structures, dominated by the Rheasilvia basin, reflects a singular event in a late stage of Vesta's surface evolution. Some earlier large impacts have left their footprints in specific remnants resembling the cases of lunar cryptomaria [5]. Vesta has escaped the fate of other differentiated protoplanets, which have been disrupted, but the crust has been shattered, which does not change the spatial distribution of the surface material entirely. This is associated with linear fragmentation features of various sizes (grabens, troughs, cracks, pit chains) which are correlated with some of the features described here.

  8. SHIPS: Spectral Hierarchical clustering for the Inference of Population Structure in genetic studies.

    PubMed

    Bouaziz, Matthieu; Paccard, Caroline; Guedj, Mickael; Ambroise, Christophe

    2012-01-01

    Inferring the structure of populations has many applications for genetic research. In addition to providing information for evolutionary studies, it can be used to account for the bias induced by population stratification in association studies. To this end, many algorithms have been proposed to cluster individuals into genetically homogeneous sub-populations. The parametric algorithms, such as Structure, are very popular but their underlying complexity and their high computational cost led to the development of faster parametric alternatives such as Admixture. Alternatives to these methods are the non-parametric approaches. Among this category, AWclust has proven efficient but fails to properly identify population structure for complex datasets. We present in this article a new clustering algorithm called Spectral Hierarchical clustering for the Inference of Population Structure (SHIPS), based on a divisive hierarchical clustering strategy, allowing a progressive investigation of population structure. This method takes genetic data as input to cluster individuals into homogeneous sub-populations and with the use of the gap statistic estimates the optimal number of such sub-populations. SHIPS was applied to a set of simulated discrete and admixed datasets and to real SNP datasets, that are data from the HapMap and Pan-Asian SNP consortium. The programs Structure, Admixture, AWclust and PCAclust were also investigated in a comparison study. SHIPS and the parametric approach Structure were the most accurate when applied to simulated datasets both in terms of individual assignments and estimation of the correct number of clusters. The analysis of the results on the real datasets highlighted that the clusterings of SHIPS were the more consistent with the population labels or those produced by the Admixture program. The performances of SHIPS when applied to SNP data, along with its relatively low computational cost and its ease of use make this method a promising

  9. Structural and Spectral Properties of Curcumin and Metal- Curcumin Complex Derived from Turmeric (Curcuma longa)

    NASA Astrophysics Data System (ADS)

    Bich, Vu Thi; Thuy, Nguyen Thi; Binh, Nguyen Thanh; Huong, Nguyen Thi Mai; Yen, Pham Nguyen Dong; Luong, Tran Thanh

    Structural and spectral properties of curcumin and metal- curcumin complex derived from turmeric (Curcuma longa) were studied by SEM and vibrational (FTIR and Raman) techniques. By comparison between curcumin commercial, fresh turmeric and a yellow powder obtained via extraction and purification of turmeric, we have found that this insoluble powder in water is curcumin. The yellow compound could complex with certain ion metal and this metal-curcumin coloring complex is water soluble and capable of producing varying hues of the same colors and having antimicrobial, cytotoxicity activities for use in foodstuffs and pharmacy. The result also demonstrates that Micro-Raman spec-troscopy is a valuable non-destructive tool and fast for investigation of a natural plant even when occurring in low concentrations.

  10. Optimal design of a spectral readout type planar waveguide-mode sensor with a monolithic structure.

    PubMed

    Wang, Xiaomin; Fujimaki, Makoto; Kato, Takafumi; Nomura, Ken-Ichi; Awazu, Koichi; Ohki, Yoshimichi

    2011-10-10

    Optical planar waveguide-mode sensor is a promising candidate for highly sensitive biosensing techniques in fields such as protein adsorption, receptor-ligand interaction and surface bacteria adhesion. To make the waveguide-mode sensor system more realistic, a spectral readout type waveguide sensor is proposed to take advantage of its high speed, compactness and low cost. Based on our previously proposed monolithic waveguide-mode sensor composed of a SiO2 waveguide layer and a single crystalline Si layer [1], the mechanism for achieving high sensitivity is revealed by numerical simulations. The optimal achievable sensitivities for a series of waveguide structures are summarized in a contour map, and they are found to be better than those of previously reported angle-scan type waveguide sensors.

  11. Relation Between Changes in Pigments' Spectral Properties and Structural Distortions of Pigment Protein Complexes (abstract)

    NASA Astrophysics Data System (ADS)

    Stoitchkova, Katerina; Andreeva, Atanaska; Busheva, Mira

    2009-04-01

    Scientists continue to investigate photosynthesis-nature's process to efficiently regulate and store energy. To explore the mechanisms of regulation we used fluorescence, resonance Raman spectroscopy, and biochemical preparative methods. For detailed analysis we applied decomposition of the low temperature steady-state fluorescence spectra. This allowed us to estimate the emission of distinct pigment protein complexes (PPC) and evaluate the fluorescence of various aggregation forms of the main light harvesting complex (LHCII), which plays a major role in the studied mechanisms. Resonance Raman spectroscopy revealed with precision the relation between changes in pigments' spectral properties and structural distortions of PPC. It was shown that aggregation of LHCII led to out-of-plane distortion, not only of neoxanthin, but also of lutein molecules. This was enhanced when the complex was embedded in thylakoid membranes (TM). It was suggested that lutein molecules are more closely related to the process of aggregation of LHCII in TM than neoxanthin.

  12. Attractors and Spectral Characteristics of Neural Structures Based on the Model of the Quantum Harmonic Oscillator

    SciTech Connect

    Rigatos, Gerasimos G.

    2007-09-06

    Neural computation based on principles of quantum mechanics can provide improved models of memory processes and brain functioning and is of importance for the realization of quantum computing machines. To this end, this paper studies neural structures with weights that follow the model of the quantum harmonic oscillator. These weights correspond to diffusing particles, which interact to each other as the theory of Brownian motion predicts. The learning of the stochastic weights (convergence of the diffusing particles to an equilibrium) is analyzed. In the case of associative memories the proposed neural model results in an exponential increase of the number of attractors. Spectral analysis shows that the stochastic weights satisfy an equation which is analogous to the principle of uncertainty.

  13. A Statistical Test for Comparing Nonnested Covariance Structure Models.

    ERIC Educational Resources Information Center

    Levy, Roy; Hancock, Gregory R.

    While statistical procedures are well known for comparing hierarchically related (nested) covariance structure models, statistical tests for comparing nonhierarchically related (nonnested) models have proven more elusive. While isolated attempts have been made, none exists within the commonly used maximum likelihood estimation framework, thereby…

  14. Synthesis, spectral characterization, crystal structure and molecular docking study of 2,7-diaryl-1,4-diazepan-5-ones

    NASA Astrophysics Data System (ADS)

    Sethuvasan, S.; Sugumar, P.; Maheshwaran, V.; Ponnuswamy, M. N.; Ponnuswamy, S.

    2016-07-01

    In this study, a series of variously substituted r-2,c-7-diaryl-1,4-diazepan-5-ones 9-16 have been synthesized using Schmidt rearrangement and are characterized by IR, mass and 1D & 2D NMR spectral data. The proton NMR coupling constant and estimated dihedral angles reveal that the compounds 9-16 prefer a chair conformation with equatorial orientation of alkyl and aryl groups. Single crystal X-ray structure has been solved for compounds 9 and 11 which also indicates the preference for distorted chair conformation with equatorial orientation of substituents. The compounds 9-16 have been docked with the structure of Methicillin-resistant Staphylococcus aureus (MRSA) and the results demonstrate that compound 10 is having better docking score and glide energy than others and it is comparable to co-crystal ligand. Furthermore, all the compounds have been evaluated for their antibacterial and antioxidant activities. All the compounds show moderate antibacterial activity and only 11 exhibits better activity against S. aures and Escherichia coli. The compounds 11, 13 and 14 exhibit half of the antioxidant power when compared to the BHT and the remaining compounds show moderate activity.

  15. Comparative modeling of InP solar cell structures

    NASA Technical Reports Server (NTRS)

    Jain, R. K.; Weinberg, I.; Flood, D. J.

    1991-01-01

    The comparative modeling of p(+)n and n(+)p indium phosphide solar cell structures is studied using a numerical program PC-1D. The optimal design study has predicted that the p(+)n structure offers improved cell efficiencies as compared to n(+)p structure, due to higher open-circuit voltage. The various cell material and process parameters to achieve the maximum cell efficiencies are reported. The effect of some of the cell parameters on InP cell I-V characteristics was studied. The available radiation resistance data on n(+)p and p(+)p InP solar cells are also critically discussed.

  16. A spectral-based clustering for structural health monitoring of the Sydney Harbour Bridge

    NASA Astrophysics Data System (ADS)

    Alamdari, Mehrisadat Makki; Rakotoarivelo, Thierry; Khoa, Nguyen Lu Dang

    2017-03-01

    This paper presents the results of a large scale Structural Health Monitoring application on the Sydney Harbour Bridge in Australia. This bridge has many structural components, and our work focuses on a subset of 800 jack arches under the traffic lane 7. Our goal is to identify which of these jack arches (if any) respond differently to the traffic input, due to potential structural damages or instrumentation issues. We propose a novel non-model-based method to achieve this objective, using a spectrum-driven feature based on the Spectral Moments (SMs) from measured responses from the jack arches. SMs contain information from the entire frequency range, thus subtle differences between the normal signals and distorted ones could be identified. Our method then applies a modified k-means- clustering algorithm to these features, followed by a selection mechanism on the clustering results to identify jack arches with abnormal responses. We performed an extensive evaluation of the proposed method using real data from the bridge. This evaluation included a control component, where the approach successfully detected jack arches with already known damage or issues. It also included a test component, which applied the method to a large set of nodes over a month of data to detect any potential anomaly. The detected anomalies turned out to have indeed system issues after further investigations.

  17. Electrically tunable infrared filter based on the liquid crystal Fabry-Perot structure for spectral imaging detection.

    PubMed

    Zhang, Huaidong; Muhammmad, Afzal; Luo, Jun; Tong, Qing; Lei, Yu; Zhang, Xinyu; Sang, Hongshi; Xie, Changsheng

    2014-09-01

    An electrically tunable infrared (IR) filter based on the liquid crystal (LC) Fabry-Perot (FP) key structure, which works in the wavelength range from 5.5 to 12 μm, is designed and fabricated successfully. Both planar reflective mirrors with a very high reflectivity of ∼95%, which are shaped by depositing a layer of aluminum (Al) film over one side of a double-sided polished zinc selenide wafer, are coupled into a dual-mirror FP cavity. The LC materials are filled into the FP cavity with a thickness of ∼7.5  μm for constructing the LC-FP filter, which is a typical type of sandwich architecture. The top and bottom mirrors of the FP cavity are further coated by an alignment layer with a thickness of ∼100  nm over Al film. The formed alignment layer is rubbed strongly to shape relatively deep V-grooves to anchor LC molecules effectively. Common optical tests show some particular properties; for instance, the existing three transmission peaks in the measured wavelength range, the minimum full width at half-maximum being ∼120  nm, and the maximum adjustment extent of the imaging wavelength being ∼500  nm through applying the voltage driving signal with a root mean square (RMS) value ranging from 0 to ∼19.8  V. The experiment results are consistent with the simulation, according to our model setup. The spectral images obtained in the long-wavelength IR range, through the LC-FP device driven by the voltage signal with a different RMS value, demonstrates the prospect of the realization of smart spectral imaging and further integrating the LC-FP filter with IR focal plane arrays. The developed LC-FP filters show some advantages, such as electrically tunable imaging wavelength, very high structural and photoelectronic response stability, small size and low power consumption, and a very high filling factor of more than 95% compared with common MEMS-FP spectral imaging approaches.

  18. Application of Video Spectral Comparator (absorption spectra) for establishing the chronological order of intersecting printed strokes and writing pen strokes.

    PubMed

    Kaur, Ridamjeet; Saini, Komal; Sood, N C

    2013-06-01

    The sequence of intersecting strokes of laser printers (black, blue, red and green) and typewriter ink (black) with the strokes of gel pen ink, ballpoint pen ink and fountain pen ink (black, blue, red and green) has been determined by studying their absorption spectra. The absorption spectra have been generated for each of the two pure inks (i.e. A and B) and points of their intersections (i.e. A over B and B over A) by using Video Spectral Comparator (VSC-2000-HR). The study was carried out with an assumption that the peak characteristics of spectra from the point of intersection should correspond to the peak characteristics of pure ink which was executed later. It was observed that the absorption spectrum of intersection corresponds with either the laser printer or the typewriter ink stroke, whether these strokes were executed earlier or later than the writing instrument strokes. As the results obtained from the study were negative, the FDEs are advised against the practice of this technique in the examination of the sequence of intersecting strokes for these specified inks.

  19. Spectrally tuned structural and pigmentary coloration of birdwing butterfly wing scales.

    PubMed

    Wilts, Bodo D; Matsushita, Atsuko; Arikawa, Kentaro; Stavenga, Doekele G

    2015-10-06

    The colourful wing patterns of butterflies play an important role for enhancing fitness; for instance, by providing camouflage, for interspecific mate recognition, or for aposematic display. Closely related butterfly species can have dramatically different wing patterns. The phenomenon is assumed to be caused by ecological processes with changing conditions, e.g. in the environment, and also by sexual selection. Here, we investigate the birdwing butterflies, Ornithoptera, the largest butterflies of the world, together forming a small genus in the butterfly family Papilionidae. The wings of these butterflies are marked by strongly coloured patches. The colours are caused by specially structured wing scales, which act as a chirped multilayer reflector, but the scales also contain papiliochrome pigments, which act as a spectral filter. The combined structural and pigmentary effects tune the coloration of the wing scales. The tuned colours are presumably important for mate recognition and signalling. By applying electron microscopy, (micro-)spectrophotometry and scatterometry we found that the various mechanisms of scale coloration of the different birdwing species strongly correlate with the taxonomical distribution of Ornithoptera species.

  20. Structure and spectral properties of dinuclear zinc complex containing semicarbazonate ligands

    NASA Astrophysics Data System (ADS)

    Jing-Lin, Wang; Jiao, Feng; Mei-Ping, Xu; Bin-Sheng, Yang

    2011-04-01

    The dinuclear Zn 2+ complex [Zn(HSSC)OAc] 2·2DMF (H 2SSC = salicylaldehyde semicarbazone; HOAc = acetic acid; DMF = N,N-dimethylfomamide) was prepared and structurally characterized by single crystal X-ray. The basic structural unit of the complex is a dinuclear complex [Zn(HSSC)OAc] 2 in which the semicarbazone ligand adopts the phenol-imine form. The deprotonated phenol group forms a one-atom bridge between the two zinc centers, and both of the zinc centers are five-coordinated. The local coordination environment of Zn 2+ can be approximately considered as square pyramidal. UV spectral studies show that the H 2SSC provides strong binding of Zn 2+ in a 1:1 ratio in solution. The conditional binding constant of the complex is lg KZn-L = 12.89 ± 0.76 in 0.05 M Tris-HCl buffer at pH 7.4. The H 2SSC exhibits an enhanced fluorescence effect by the addition of Zn 2+, and affords an excellent selectivity for Zn 2+ under physiological conditions.

  1. Temperature dependence of aggregated structure of β-carotene by absorption spectral experiment and simulation

    NASA Astrophysics Data System (ADS)

    Lu, Liping; Wu, Jie; Wei, Liangshu; Wu, Fang

    2016-12-01

    β-carotene can self-assemble to form J- or H-type aggregate in hydrophilic environments, which is crucial for the proper functioning of biological system. Although several ways controlling the formation of the two types of aggregate in hydrated ethanol have been investigated in recent years, our study provided another way to control whether J- or H- β-carotene was formed and presented a method to investigate the aggregated structure. For this purpose, the aggregates of β-carotene formed at different temperatures were studied by UV-Vis spectra and a computational method based on Frenkel exciton was applied to simulate the absorption spectra to obtain the aggregated structure of the β-carotene. The analysis showed that β-carotene formed weakly coupled H-aggregate at 15 °C in 1:1 ethanol-water solvent, and with the increase of temperature it tended to form J-type of aggregate. The absorption spectral simulation based on one-dimensional Frenkel exciton model revealed that good fit with the experiment was obtained with distance between neighbor molecules r = 0.82 nm, disorder of the system D = 1500 cm- 1 for H-type and r = 1.04 nm, D = 1800 cm- 1 for J-type.

  2. Spectral structure and linear mechanisms in a 'rapidly' distorted boundary layer

    NASA Astrophysics Data System (ADS)

    Diwan, Sourabh; Morrison, Jonathan

    2016-11-01

    A characteristic feature of a turbulent boundary layer (TBL) at high Reynolds numbers is the presence of coherent motions such as the 'large scale motions' and 'superstructures'. In this work we attempt to mimic such coherent motions and their spectral structure using a simplified experimental arrangement of a boundary layer flow over a flat plate subjected to grid-generated turbulence and/or localized patch of surface roughness. The velocity measurements done downstream of a grit roughness patch (in absence of grid turbulence) show that over a certain distance the energy spectrum of streamwise velocity fluctuations shows a bi-modal shape which resembles that found in a high-Re TBL. We also carry out experiments with both grid turbulence and grit roughness present and show that it is possible to 'synthesize' the structure of a TBL in the wall-normal direction, in the limited context of streamwise coherent motions, using the present experimental design. These results indicate that the predictions of the Rapid Distortion Theory (RDT) can be applied to the present case in a region close to the plate leading edge, and we examine the linearized effects of 'blocking' and 'shear' on turbulent fluctuations near the edge of the boundary layer and close to the wall in the framework of the RDT. We acknowledge financial support from EPSRC (Grant No. EP/1037938).

  3. Spectral element method for band structures of three-dimensional anisotropic photonic crystals

    NASA Astrophysics Data System (ADS)

    Luo, Ma; Liu, Qing Huo

    2009-11-01

    A spectral element method (SEM) is introduced for accurate calculation of band structures of three-dimensional anisotropic photonic crystals. The method is based on the finite-element framework with curvilinear hexahedral elements. Gauss-Lobatto-Legendre polynomials are used to construct the basis functions. In order to suppress spurious modes, mixed-order vector basis functions are employed and the Bloch periodic boundary condition is imposed into the basis functions with tangential components at the boundary by multiplying a Bloch phase factor. The fields and coordinates in the curvilinear hexahedral elements are mapped to the reference domain by covariant mapping, which preserves the continuity of tangential components of the field. Numerical results show that the SEM has exponential convergence for both square-lattice and triangular-lattice photonic crystals. The sampling density as small as 3.4 points per wavelength can achieve accuracy as high as 99.9%. The band structures of several modified woodpile photonic crystals are calculated by using the SEM.

  4. Spectral element method for band structures of three-dimensional anisotropic photonic crystals.

    PubMed

    Luo, Ma; Liu, Qing Huo

    2009-11-01

    A spectral element method (SEM) is introduced for accurate calculation of band structures of three-dimensional anisotropic photonic crystals. The method is based on the finite-element framework with curvilinear hexahedral elements. Gauss-Lobatto-Legendre polynomials are used to construct the basis functions. In order to suppress spurious modes, mixed-order vector basis functions are employed and the Bloch periodic boundary condition is imposed into the basis functions with tangential components at the boundary by multiplying a Bloch phase factor. The fields and coordinates in the curvilinear hexahedral elements are mapped to the reference domain by covariant mapping, which preserves the continuity of tangential components of the field. Numerical results show that the SEM has exponential convergence for both square-lattice and triangular-lattice photonic crystals. The sampling density as small as 3.4 points per wavelength can achieve accuracy as high as 99.9%. The band structures of several modified woodpile photonic crystals are calculated by using the SEM.

  5. A Spectral Element Approach for Modeling of Wave-Based Structural Health Monitoring Systems

    NASA Astrophysics Data System (ADS)

    Schulte, Rolf T.; Fritzen, Claus-Peter

    2010-09-01

    During the last decades, guided waves have shown great potential for Structural Health Monitoring (SHM) applications. These waves can be excited and sensed by piezoelectric elements that can be permanently attached onto a structure offering online monitoring capability. As the setup of wave based SHM systems may be very difficult and time consuming there is a growing demand for efficient simulation tools providing the opportunity to design wave based SHM systems in a virtual environment. As usually high frequency waves are used, the associated short wavelength leads to the necessity of a very dense mesh, which makes conventional finite elements not well suited for this purpose. Therefore a flat shell spectral element approach is presented in this contribution. By including electromechanical coupling an SHM system can be simulated entirely from actuator voltage to sensor voltage. The focus of this contribution is the analysis of the effect of delaminations on propagating waves. A forward increment Lagrange multiplier method is used to simulate contact within the delaminated area. A model validation is performed using measured data of an anisotropic CFRP-plate.

  6. Spectrally tuned structural and pigmentary coloration of birdwing butterfly wing scales

    PubMed Central

    Wilts, Bodo D.; Matsushita, Atsuko; Arikawa, Kentaro; Stavenga, Doekele G.

    2015-01-01

    The colourful wing patterns of butterflies play an important role for enhancing fitness; for instance, by providing camouflage, for interspecific mate recognition, or for aposematic display. Closely related butterfly species can have dramatically different wing patterns. The phenomenon is assumed to be caused by ecological processes with changing conditions, e.g. in the environment, and also by sexual selection. Here, we investigate the birdwing butterflies, Ornithoptera, the largest butterflies of the world, together forming a small genus in the butterfly family Papilionidae. The wings of these butterflies are marked by strongly coloured patches. The colours are caused by specially structured wing scales, which act as a chirped multilayer reflector, but the scales also contain papiliochrome pigments, which act as a spectral filter. The combined structural and pigmentary effects tune the coloration of the wing scales. The tuned colours are presumably important for mate recognition and signalling. By applying electron microscopy, (micro-)spectrophotometry and scatterometry we found that the various mechanisms of scale coloration of the different birdwing species strongly correlate with the taxonomical distribution of Ornithoptera species. PMID:26446560

  7. A Spectral Element Approach for Modeling of Wave-Based Structural Health Monitoring Systems

    SciTech Connect

    Schulte, Rolf T.; Fritzen, Claus-Peter

    2010-09-30

    During the last decades, guided waves have shown great potential for Structural Health Monitoring (SHM) applications. These waves can be excited and sensed by piezoelectric elements that can be permanently attached onto a structure offering online monitoring capability. As the setup of wave based SHM systems may be very difficult and time consuming there is a growing demand for efficient simulation tools providing the opportunity to design wave based SHM systems in a virtual environment. As usually high frequency waves are used, the associated short wavelength leads to the necessity of a very dense mesh, which makes conventional finite elements not well suited for this purpose. Therefore a flat shell spectral element approach is presented in this contribution. By including electromechanical coupling an SHM system can be simulated entirely from actuator voltage to sensor voltage. The focus of this contribution is the analysis of the effect of delaminations on propagating waves. A forward increment Lagrange multiplier method is used to simulate contact within the delaminated area. A model validation is performed using measured data of an anisotropic CFRP-plate.

  8. Comparative testing of nondestructive examination techniques for concrete structures

    NASA Astrophysics Data System (ADS)

    Clayton, Dwight A.; Smith, Cyrus M.

    2014-03-01

    A multitude of concrete-based structures are typically part of a light water reactor (LWR) plant to provide foundation, support, shielding, and containment functions. Concrete has been used in the construction of nuclear power plants (NPPs) because of three primary properties, its inexpensiveness, its structural strength, and its ability to shield radiation. Examples of concrete structures important to the safety of LWR plants include containment building, spent fuel pool, and cooling towers. Comparative testing of the various NDE concrete measurement techniques requires concrete samples with known material properties, voids, internal microstructure flaws, and reinforcement locations. These samples can be artificially created under laboratory conditions where the various properties can be controlled. Other than NPPs, there are not many applications where critical concrete structures are as thick and reinforced. Therefore, there are not many industries other than the nuclear power plant or power plant industry that are interested in performing NDE on thick and reinforced concrete structures. This leads to the lack of readily available samples of thick and heavily reinforced concrete for performing NDE evaluations, research, and training. The industry that typically performs the most NDE on concrete structures is the bridge and roadway industry. While bridge and roadway structures are thinner and less reinforced, they have a good base of NDE research to support their field NDE programs to detect, identify, and repair concrete failures. This paper will summarize the initial comparative testing of two concrete samples with an emphasis on how these techniques could perform on NPP concrete structures.

  9. Photovoltaic spectral responsivity measurements

    SciTech Connect

    Emery, K.; Dunlavy, D.; Field, H.; Moriarty, T.

    1998-09-01

    This paper discusses the various elemental random and nonrandom error sources in typical spectral responsivity measurement systems. The authors focus specifically on the filter and grating monochrometer-based spectral responsivity measurement systems used by the Photovoltaic (PV) performance characterization team at NREL. A variety of subtle measurement errors can occur that arise from a finite photo-current response time, bandwidth of the monochromatic light, waveform of the monochromatic light, and spatial uniformity of the monochromatic and bias lights; the errors depend on the light source, PV technology, and measurement system. The quantum efficiency can be a function of he voltage bias, light bias level, and, for some structures, the spectral content of the bias light or location on the PV device. This paper compares the advantages and problems associated with semiconductor-detector-based calibrations and pyroelectric-detector-based calibrations. Different current-to-voltage conversion and ac photo-current detection strategies employed at NREL are compared and contrasted.

  10. MODBASE, a database of annotated comparative protein structure models.

    PubMed

    Pieper, Ursula; Eswar, Narayanan; Stuart, Ashley C; Ilyin, Valentin A; Sali, Andrej

    2002-01-01

    MODBASE (http://guitar.rockefeller.edu/modbase) is a relational database of annotated comparative protein structure models for all available protein sequences matched to at least one known protein structure. The models are calculated by MODPIPE, an automated modeling pipeline that relies on PSI-BLAST, IMPALA and MODELLER. MODBASE uses the MySQL relational database management system for flexible and efficient querying, and the MODVIEW Netscape plugin for viewing and manipulating multiple sequences and structures. It is updated regularly to reflect the growth of the protein sequence and structure databases, as well as improvements in the software for calculating the models. For ease of access, MODBASE is organized into different datasets. The largest dataset contains models for domains in 304 517 out of 539 171 unique protein sequences in the complete TrEMBL database (23 March 2001); only models based on significant alignments (PSI-BLAST E-value < 10(-4)) and models assessed to have the correct fold are included. Other datasets include models for target selection and structure-based annotation by the New York Structural Genomics Research Consortium, models for prediction of genes in the Drosophila melanogaster genome, models for structure determination of several ribosomal particles and models calculated by the MODWEB comparative modeling web server.

  11. Comparative study of spectral diffuse-only and diffuse-specular radiative transfer models and field-collected data in the LWIR

    NASA Astrophysics Data System (ADS)

    Stoyanov, Dimitar M.; Marciniak, Michael A.; Meola, Joseph

    2015-09-01

    The sensitivity of hyper-spectral remote sensing to the directional reflectance of surfaces was studied using both laboratory and field measurements. Namely, the effects of the specular- and diffuse-reflectance properties of a set of eight samples, ranging from high to low in both total reflectance and specularity, on diffuse-only and diffusespecular radiative transfer models in the long-wave infrared (LWIR, 7-14-μm wavelength) were studied. The samples were measured in the field as a set of eight panels, each in two orientations, with surface normal pointing toward zenith and tipped at 45° from zenith. The field-collected data also included down-welling spectral sky radiance at several angles from zenith to the horizon, ground spectral radiance, panel spectral radiances in both orientations, Infragold® spectral radiances in both orientations near each panel location, and panel temperatures. Laboratory measurements included spectral hemispherical, specular and diffuse directional reflectance (HDR, SDR and DDR) for each sample for several reflectance angles with respect to the surface normal. The diffuse-only radiative transfer model used the HDR data, while the diffuse-specular model used the SDR and DDR data. Both calculated spectral reflected and self-emitted radiances for each panel, using the field-collected sky radiance data to avoid uncertainties associated with atmospheric models. The modeled spectral radiances were then compared to the field-collected values to quantify differences in moving from an HDR-based model to an SDR/DDR model in the LWIR for a variety of surface-reflectance types.

  12. Structural Order in Water: Comparison between the Spectral Analysis of Raman Data and Molecular Dynamics Results

    NASA Astrophysics Data System (ADS)

    Faginas Lago, N.; Paolantoni, M.; Laganá, A.; Alberti, M.

    2007-12-01

    We utilize molecular dynamics calculations performed using the DL_POLY suite of programs to test the validity of two popular water interaction models and to better understand the structural order of its liquid phase by comparing calculated properties with the Raman spectrum.

  13. Structures of School Systems Worldwide: A Comparative Study

    ERIC Educational Resources Information Center

    Popov, Nikolay

    2012-01-01

    In the past 20 years I have been examining the structures of school systems worldwide. This ongoing research has been enriched by the findings obtained from the lecture course on Comparative Education I have been delivering to students in the Bachelor and Master's Education Programs at Sofia University, Bulgaria. This paper presents some results…

  14. Structural and Spectral Features of Selenium Nanospheres Produced by Se-Respiring Bacteria

    USGS Publications Warehouse

    Oremland, R.S.; Herbel, M.J.; Blum, J.S.; Langley, S.; Beveridge, T.J.; Ajayan, P.M.; Sutto, T.; Ellis, A.V.; Curran, S.

    2004-01-01

    Certain anaerobic bacteria respire toxic selenium oxyanions and in doing so produce extracellular accumulations of elemental selenium [Se(0)]. We examined three physiologically and phylogenetically diverse species of selenate- and selenite-respiring bacteria, Sulfurospirillum barnesii, Bacillus selenitireducens, and Selenihalanaerobacter shriftii, for the occurrence of this phenomenon. When grown with selenium oxyanions as the electron acceptor, all of these organisms formed extracellular granules consisting of stable, uniform nanospheres (diameter, ???300 nm) of Se(0) having monoclinic crystalline structures. Intracellular packets of Se(0) were also noted. The number of intracellular Se(0) packets could be reduced by first growing cells with nitrate as the electron acceptor and then adding selenite ions to washed suspensions of the nitrate-grown cells. This resulted in the formation of primarily extracellular Se nanospheres. After harvesting and cleansing of cellular debris, we observed large differences in the optical properties (UV-visible absorption and Raman spectra) of purified extracellular nanospheres produced in this manner by the three different bacterial species. The spectral properties in turn differed substantially from those of amorphous Se(0) formed by chemical oxidation of H2Se and of black, vitreous Se(0) formed chemically by reduction of selenite with ascorbate. The microbial synthesis of Se(0) nanospheres results in unique, complex, compacted nanostructural arrangements of Se atoms. These arrangements probably reflect a diversity of enzymes involved in the dissimilatory reduction that are subtly different in different microbes. Remarkably, these conditions cannot be achieved by current methods of chemical synthesis.

  15. Coherence and spectral weight transfer in the dynamic structure factor of cold lattice bosons

    NASA Astrophysics Data System (ADS)

    Zaleski, T. A.; Kopeć, T. K.

    2017-01-01

    Ultracold atoms have been used to create novel correlated quantum phases allowing to address many solid-state physics problems using the quasi-particle concept, which is the foundation of our understanding of many-body quantum systems. For bosons, the simplest kinds of excited states involve two particles and they are connected to the dynamic structure factor S (k , ω) , measured using Bragg spectroscopy, similarly to the angle-resolved photoemission spectroscopy (ARPES) in solid state physics - a major tool in the study of high-Tc cuprates. Calculation of S (k , ω) requires a significant numerical effort to determine multidimensional convolutions of momentum and frequency dependent constituents functions, which we achieve using parallelized fast Fourier transform. As a result, we are able to show that spectral weight transfer between low and high energies is an intrinsic property of the strongly correlated Bose system in close analogy to the doped Mott-Hubbard electronic insulator. Furthermore, the appearance of sharp coherence peaks in the superfluid phase of the cold bosons closely resembles the formation of sharply defined quasiparticle excitations below Tc in cuprates suggesting an intimate connection between the intrinsic nature of these seemingly different systems.

  16. Discrimination of the spectral structures of sound signals on the background of interference.

    PubMed

    Supin, A Ya

    2008-06-01

    Presentation of test signals consisting of sounds with rippled spectra allowed measurements of the frequency-resolving ability (FRA) of hearing to be performed in humans without using frequency-dependent masking techniques. This allowed studies of changes in FRA in the presence of noise interference. In conditions of diotic presentation (to both ears in parallel) of the test signal and noise, FRA decreased significantly if the interference frequency was lower or equal to the test signal frequency. The relationship between this effect and the sound intensity and noise:signal ratio varied for low-frequency noise and for noise at the same frequency as the test signal, which indicates that these two types of interference have different mechanisms. However, in both cases, noise of sufficient intensity led to a complete inability to discriminate the fine spectral structure of the test signal. In dichotic presentation (test signal to one ear, noise to the other), noise had virtually no effect on FRA over a wide range of test signal and noise frequencies and noise:signal ratios. Thus, there was essentially complete dichotic release of FRA from the effects noise, which has potential to be used in constructing prosthetic hearing devices.

  17. Supramolecular structure and substituents effect on the spectral studies of oxovanadium(IV) azodyes complexes

    NASA Astrophysics Data System (ADS)

    Diab, M. A.; El-Bindary, A. A.; El-Sonbati, A. Z.; Salem, O. L.

    2012-06-01

    A series of novel bidentate azodye quinoline ligands were synthesized with various p-aromatic amines like p-(OCH3, CH3, H, Cl and NO2) in pyridine medium. All ligands have been characterized on the basis of elemental analysis, IR and 1H NMR data. The ligands obtained contain Ndbnd N and phenolic functional groups in different positions with respect to the quinoline group. IR spectra show that the azo compounds (HLn) act as monobasic bidentate ligand by coordinating via the azo nitrogen atom of azodye (sbnd Ndbnd Nsbnd ) and oxygen atom of the phenolic group thereby forming a six-membered chelating ring and concomitant formation of an intramolecular hydrogen bond. Novel vanadium azodye complexes of these ligands with general formula [OV(L1-5)2(OH2)] have been prepared by interaction of vanadyl sulfate pentahydrate with DMF solution of the appropriate ligands. The resulting complexes have been characterized on the basis of elemental analysis, molar conductance and magnetic measurements, infrared and electronic spectral studies. Suitable distorted octahedral structures have been proposed for these complexes. The Hammett's constant is also discussed.

  18. Crustal Structure of the Iceland Region from Spectrally Correlated Free-air and Terrain Gravity Data

    NASA Technical Reports Server (NTRS)

    Leftwich, T. E.; vonFrese, R. R. B.; Potts, L. V.; Roman, D. R.; Taylor, P. T.

    2003-01-01

    Seismic refraction studies have provided critical, but spatially restricted constraints on the structure of the Icelandic crust. To obtain a more comprehensive regional view of this tectonically complicated area, we spectrally correlated free-air gravity anomalies against computed gravity effects of the terrain for a crustal thickness model that also conforms to regional seismic and thermal constraints. Our regional crustal thickness estimates suggest thickened crust extends up to 500 km on either side of the Greenland-Scotland Ridge with the Iceland-Faeroe Ridge crust being less extended and on average 3-5 km thinner than the crust of the Greenland-Iceland Ridge. Crustal thickness estimates for Iceland range from 25-35 km in conformity with seismic predictions of a cooler, thicker crust. However, the deepening of our gravity-inferred Moho relative to seismic estimates at the thermal plume and rift zones of Iceland suggests partial melting. The amount of partial melting may range from about 8% beneath the rift zones to perhaps 20% above the plume core where mantle temperatures may be 200-400 C above normal. Beneath Iceland, areally limited regions of partial melting may also be compositionally and mechanically layered and intruded. The mantle plume appears to be centered at (64.6 deg N, 17.4 deg W) near the Vatnajokull Glacier and the central Icelandic neovolcanic zones.

  19. Efficient global wave propagation adapted to 3-D structural complexity: a pseudospectral/spectral-element approach

    NASA Astrophysics Data System (ADS)

    Leng, Kuangdai; Nissen-Meyer, Tarje; van Driel, Martin

    2016-12-01

    We present a new, computationally efficient numerical method to simulate global seismic wave propagation in realistic 3-D Earth models. We characterize the azimuthal dependence of 3-D wavefields in terms of Fourier series, such that the 3-D equations of motion reduce to an algebraic system of coupled 2-D meridian equations, which is then solved by a 2-D spectral element method (SEM). Computational efficiency of such a hybrid method stems from lateral smoothness of 3-D Earth models and axial singularity of seismic point sources, which jointly confine the Fourier modes of wavefields to a few lower orders. We show novel benchmarks for global wave solutions in 3-D structures between our method and an independent, fully discretized 3-D SEM with remarkable agreement. Performance comparisons are carried out on three state-of-the-art tomography models, with seismic period ranging from 34 s down to 11 s. It turns out that our method has run up to two orders of magnitude faster than the 3-D SEM, featured by a computational advantage expanding with seismic frequency.

  20. Diffusion and flow in a porous structure by the gradient spin echo spectral analysis

    NASA Astrophysics Data System (ADS)

    Stepišnik, Janez; Mohorič, Aleš; Duh, Andrej

    2001-12-01

    The frequency analysis of relation between the NMR gradient spin echo method and the correlation of molecular motion throws a new light upon the measurement of molecular transport in porous media by magnetic resonance. The spectral analysis provides, in some other way, a known Dt early time dependence of attenuation or the pulse gradient spin echo sequence, and at intermediate times, it gives a not-known Dpt+ d(1-exp(- t/ τr)). When the displacements are getting larger than the size of compartments, the spin echo is levelling into a time-independent asymptote. In the system of packed poly-dispersed beds, the spin echo measurement of flow dispersion perpendicular to flows confirms the predicted spin echo decay. It demonstrates a clear distinction between different time regimes of signal decay, from which different properties of the porous structure can be revealed. The results gives almost identical long-time dispersion coefficient, D‧= Dp, for different flows, but the shortening of the dispersion correlation time τr with the increase of interstitial velocity. In combination with the modulated gradient sequence, the method extends the measuring range of spin echo over multi-pore length scale, and opens a new way to provide information about important properties of porous media like average pore size, the interconnectivity and the tortuosity.

  1. Crustal Structure of the Iceland Region from Spectrally Correlated Free-air and Terrain Gravity Data

    NASA Technical Reports Server (NTRS)

    Leftwich, T. E.; vonFrese, R. R. R. B.; Potts, L. V.; Roman, D. R.; Taylor, Patrick T.

    2003-01-01

    Seismic refraction studies have provided critical, but spatially restricted constraints on the structure of the Icelandic crust. To obtain a more comprehensive regional view of this tectonically complicated area, we spectrally correlated free-air gravity anomalies against computed gravity effects of the terrain for a crustal thickness model that also conforms to regional seismic and thermal constraints. Our regional crustal thickness estimates suggest thickened crust extends up to 500 km on either side of the Greenland-Scotland Ridge with the Iceland-Faeroe Ridge crust being less extended and on average 3-5 km thinner than the crust of the Greenland-Iceland Ridge. Crustal thickness estimates for Iceland range from 25-35 km in conformity with seismic predictions of a cooler, thicker crust. However, the deepening of our gravity-inferred Moho relative to seismic estimates at the thermal plume and rift zones of Iceland suggests partial melting. The amount of partial melting may range from about 8% beneath the rift zones to perhaps 20% above the plume core where mantle temperatures may be 200-400 C above normal. Beneath Iceland, areally limited regions of partial melting may also be compositionally and mechanically layered

  2. Methodology for assessment of structural vibrations by spectral domain optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Gao, Simon S.; Raphael, Patrick; Xia, Anping; Park, Jesung; Carbajal, Esteban; Applegate, Brian E.; Oghalai, John S.

    2012-02-01

    Clinical diagnosis of cochlear dysfunction typically remains incomplete due to a lack of proper diagnostic methods. Medical imaging modalities can only detect gross changes in the cochlea, and non-invasive in vivo cochlear measurements are scarce. As a result, extensive efforts have been made to adapt optical coherence tomography (OCT) techniques to analyze and study the cochlea. Herein, we detail the methods for measuring vibration using OCT. We used spectral domain OCT with ~950 nm as the center wavelength and a bandwidth of ~80 nm. The custom spectrometer used was based on a high speed line scan camera which is capable of line rates up to 28 kHz. The signal-to- noise ratio of the system was ~90 dB. The data collection and processing software was written in LabVIEW and MATLAB. We tested whether streaming directly from the camera, writing the data to multiple hard drives in the RAID- 0 configuration, and processing using the GPU shortened experiment times. We then analyzed the A-line phase noise over several hundred milliseconds and growth curves from a piezoelectric element. We believe this is the first step towards a diagnostic device which generates vibration information of cochlear structures.

  3. Control of Spectral Interference Patterns in Broad Rabi Sidebands: Terahertz Quasi-Comb Structures

    NASA Astrophysics Data System (ADS)

    Romanov, Dmitri; Filin, Alex; Levis, Robert

    2015-05-01

    Coherent broadband radiation in the form of Rabi sidebands with an effective bandwidth ~ 200 meV is generated in atmospheric-pressure gases in pump-probe experiments. The dynamic Rabi sidebands show characteristic fringe patterns of spatial-spectral interference, whose variable contrast is affected by decoherence processes. The spectrum envelope, the fringe contrast, and the fringe spacing variation in these patterns can be controlled by the intensity and shape of the probe pulse. We demonstrate such control experimentally and report analytic and numerical investigation of possibilities to produce a comb-like fringe structure. The sideband envelope is mainly determined by the sharpness of the driving probe pulse. The fringe contrast, defined by the maximum-to-minimum difference, depends strongly on the asymmetry of the driving pulse. The variation of inter-peak distance within a sideband was controlled using the temporal shape of the driving pulse. In a particular case of blue-shifted sideband emitted by excited oxygen atoms driven by a picosecond pulse of 800 nm carrier wavelength and ~ 0.05 TW/ cm2 intensity, a super-Gaussian pulse shape leads to almost equidistant fringes producing a comb-like spectrum over the interval from 1.60 to 1.66 eV. This work is supported through the Air Force Office of Scientific Research, MURI grant FA9550-10-1-0561.

  4. Comparing High-latitude Ionospheric and Thermospheric Lagrangian Coherent Structures

    NASA Astrophysics Data System (ADS)

    Wang, N.; Ramirez, U.; Flores, F.; Okic, D.; Datta-Barua, S.

    2015-12-01

    Lagrangian Coherent Structures (LCSs) are invisible boundaries in time varying flow fields that may be subject to mixing and turbulence. The LCS is defined by the local maxima of the finite time Lyapunov exponent (FTLE), a scalar field quantifying the degree of stretching of fluid elements over the flow domain. Although the thermosphere is dominated by neutral wind processes and the ionosphere is governed by plasma electrodynamics, we can compare the LCS in the two modeled flow fields to yield insight into transport and interaction processes in the high-latitude IT system. For obtaining thermospheric LCS, we use the Horizontal Wind Model 2014 (HWM14) [1] at a single altitude to generate the two-dimensional velocity field. The FTLE computation is applied to study the flow field of the neutral wind, and to visualize the forward-time Lagrangian Coherent Structures in the flow domain. The time-varying structures indicate a possible thermospheric LCS ridge in the auroral oval area. The results of a two-day run during a geomagnetically quiet period show that the structures are diurnally quasi-periodic, thus that solar radiation influences the neutral wind flow field. To find the LCS in the high-latitude ionospheric drifts, the Weimer 2001 [2] polar electric potential model and the International Geomagnetic Reference Field 11 [3] are used to compute the ExB drift flow field in ionosphere. As with the neutral winds, the Lagrangian Coherent Structures are obtained by applying the FTLE computation. The relationship between the thermospheric and ionospheric LCS is analyzed by comparing overlapping FTLE maps. Both a publicly available FTLE solver [4] and a custom-built FTLE computation are used and compared for validation [5]. Comparing the modeled IT LCSs on a quiet day with the modeled IT LCSs on a storm day indicates important factors on the structure and time evolution of the LCS.

  5. Assessing forest structure and function from spectral transmittance measurements: a case study in a Mediterranean holm oak forest.

    PubMed

    Serrano, Lydia; Peñuelas, Josep

    2005-01-01

    Annual changes in structural attributes and seasonal dynamics in water content, photosynthetic rate and light-use efficiency (LUE) were assessed by spectral transmittance for 4 years (1999-2003) in six stands of a Mediterranean holm oak forest. Green biomass, total biomass and leaf area index (LAI) were determined. In 1999, seasonal dynamics of net carbon dioxide (CO2) exchange and water content were measured. We recorded photosynthetically active radiation (PAR) transmittance and hyperspectral transmittance in the 400-1100 nm region and derived reflectance-based vegetation indices. Transmittance over the PAR region derived from either ceptometer or spectroradiometer measurements (PART and TPAR, respectively) was related to green and total biomass. Both PART and TPAR were also related to LAI (r=0.79 and r=0.70, respectively, P <0.001) and were appropriate for comparison among stands, whereas subtle changes in LAI within a stand were better assessed by the transmittance amplitude in the red edge region (TRE) (within a stand, r=0.77-0.99, P <0.001). Spectral transmittance-based indices successfully captured physiological processes that occurred on temporal (seasonal) and spatial scales. The transmittance-based water index (TWI) was related to both foliage and canopy water content (r=0.69, P <0.001). Estimates of foliage and canopy water content improved in dense (closed) stands (r=0.84 and r=0.87, respectively, P <0.001) compared with low-density stands. Under non-drought conditions, transmittance-based photochemical reflectance index (TPRI) was related to LUE (r=0.58, P <0.05) and net CO2 exchange (r=0.72, P <0.01), and the combined TPAR x TPRI index greatly improved these relationships (r=0.93 and r=0.84, respectively, P <0.01), indicating that both structural and physiological adjustments modified CO2 fixation capacity in these forest stands. Our novel approach to the study of transmitted radiation provides a tool for estimating structural and functional variables

  6. Chemical, Spectral, Structural, and Charge Transport Properties of the ’Molecular Metals’ Produced by Iodination of Nickel Phthalocyanine.

    DTIC Science & Technology

    1980-07-17

    AD-AOA7 553 NOR ~EST.R. UNIV EVANSTON IL DEPT OF CHEMISTRY F/G 7/3 CHEMISCAL SPECTRAL, ESTRUCTURAL , AND CHARGE TRANSPORTp POPERTIES--ETC(U) JUL A0 R P...SCARINGE, C J SCHRAMM NORI 00477-C 1231 UNCLASSIFIED TRSD N Eh~h~hEEEEE~hhhhEEE-7EEsoon’mhhhh LEVEL OFFICE OF-ZAVARSEARCH Contract’TPN𔃺𔃻-77-C-#231... J Task N-o-. 053-6".... YECINICAL REPTONO. 11 00( Chemical, Spectral, Structural, and Charge Transport Properties Of The 6Molecular MetalssProduced

  7. Spectral and Structure Modeling of Low and High Mass Young Stars Using a Radiative Trasnfer Code

    NASA Astrophysics Data System (ADS)

    Robson Rocha, Will; Pilling, Sergio

    The spectroscopy data from space telescopes (ISO, Spitzer, Herchel) shows that in addition to dust grains (e.g. silicates), there is also the presence of the frozen molecular species (astrophysical ices, such as H _{2}O, CO, CO _{2}, CH _{3}OH) in the circumstellar environments. In this work we present a study of the modeling of low and high mass young stellar objects (YSOs), where we highlight the importance in the use of the astrophysical ices processed by the radiation (UV, cosmic rays) comes from stars in formation process. This is important to characterize the physicochemical evolution of the ices distributed by the protostellar disk and its envelope in some situations. To perform this analysis, we gathered (i) observational data from Infrared Space Observatory (ISO) related with low mass protostar Elias29 and high mass protostar W33A, (ii) absorbance experimental data in the infrared spectral range used to determinate the optical constants of the materials observed around this objects and (iii) a powerful radiative transfer code to simulate the astrophysical environment (RADMC-3D, Dullemond et al, 2012). Briefly, the radiative transfer calculation of the YSOs was done employing the RADMC-3D code. The model outputs were the spectral energy distribution and theoretical images in different wavelengths of the studied objects. The functionality of this code is based on the Monte Carlo methodology in addition to Mie theory for interaction among radiation and matter. The observational data from different space telescopes was used as reference for comparison with the modeled data. The optical constants in the infrared, used as input in the models, were calculated directly from absorbance data obtained in the laboratory of both unprocessed and processed simulated interstellar samples by using NKABS code (Rocha & Pilling 2014). We show from this study that some absorption bands in the infrared, observed in the spectrum of Elias29 and W33A can arises after the ices

  8. Accuracy of functional surfaces on comparatively modeled protein structures

    PubMed Central

    Zhao, Jieling; Dundas, Joe; Kachalo, Sema; Ouyang, Zheng; Liang, Jie

    2012-01-01

    Identification and characterization of protein functional surfaces are important for predicting protein function, understanding enzyme mechanism, and docking small compounds to proteins. As the rapid speed of accumulation of protein sequence information far exceeds that of structures, constructing accurate models of protein functional surfaces and identify their key elements become increasingly important. A promising approach is to build comparative models from sequences using known structural templates such as those obtained from structural genome projects. Here we assess how well this approach works in modeling binding surfaces. By systematically building three-dimensional comparative models of proteins using Modeller, we determine how well functional surfaces can be accurately reproduced. We use an alpha shape based pocket algorithm to compute all pockets on the modeled structures, and conduct a large-scale computation of similarity measurements (pocket RMSD and fraction of functional atoms captured) for 26,590 modeled enzyme protein structures. Overall, we find that when the sequence fragment of the binding surfaces has more than 45% identity to that of the tempalte protein, the modeled surfaces have on average an RMSD of 0.5 Å, and contain 48% or more of the binding surface atoms, with nearly all of the important atoms in the signatures of binding pockets captured. PMID:21541664

  9. Ion aggregation in high salt solutions. II. Spectral graph analysis of water hydrogen-bonding network and ion aggregate structures.

    PubMed

    Choi, Jun-Ho; Cho, Minhaeng

    2014-10-21

    Graph theory in mathematics and computer science is the study of graphs that are structures with pairwise connections between any objects. Here, the spectral graph theory and molecular dynamics simulation method are used to describe both morphological variation of ion aggregates in high salt solutions and ion effects on water hydrogen-bonding network structure. From the characteristic value analysis of the adjacency matrices that are graph theoretical representations of ion clusters, ion networks, and water H-bond structures, we obtained the ensemble average eigenvalue spectra revealing intricate connectivity and topology of ion aggregate structure that can be classified as either ion cluster or ion network. We further show that there is an isospectral relationship between the eigenvalue spectra of ion networks in high KSCN solutions and those of water H-bonding networks. This reveals the isomorphic relationship between water H-bond structure and ion-ion network structure in KSCN solution. On the other hand, the ion clusters formed in high NaCl solutions are shown to be graph-theoretically and morphologically different from the ion network structures in KSCN solutions. These observations support the bifurcation hypothesis on large ion aggregate growth mechanism via either ion cluster or ion network formation. We thus anticipate that the present spectral graph analyses of ion aggregate structures and their effects on water H-bonding network structures in high salt solutions can provide important information on the specific ion effects on water structures and possibly protein stability resulting from protein-water interactions.

  10. Imaging the crustal structure of the valley of Mexico and higher mode identification using H/V spectral ratio

    NASA Astrophysics Data System (ADS)

    Rivet, D.; Campillo, M.; Sanchez-Sesma, F.; Singh, S. K.

    2012-04-01

    We reconstruct Rayleigh and Love waves from cross-correlations of ambient seismic noise recorded at 19 broad-band stations of the MesoAmerica Seismic Experiment (MASE) and Valley of Mexico Experiment (VMEX). The cross-correlations are computed over 2 years of noise records for the 8 MASE stations and over 1 year for the 11 VMEX stations. We use surface waves with sufficient signal-to-noise ratio to measure group velocity dispersion curves at period of 0.5 to 3 seconds. For paths within the soft quaternary sediments basin, the maximum energy is observed at velocity higher than expected for the fundamental mode. This observation suggests the importance of higher modes as the main vectors of energy in such complex structures. To perform a reliable inversion of the velocity structure beneath the valley, an identification of these dominants modes is required. To identify the modes of surface waves we use the spectral ratio of the horizontal components over the vertical component (H/V) measured on seismic coda. We compare the observed values with the theoretical H/V for the velocity model deduced from surface wave dispersion when assuming a particular mode. H/V ratio in the coda is computed under the hypothesis of equipartition of a diffuse field in a layered medium following Margerin et al. [2009] and Sánchez-Sesma et al. [2011]. We processed several events to ensure that the observed H/V is stable. The comparison of the modelled dispersion and H/V ratio allows for mode identification, and consequently to recover the velocity model of the structure. We conclude on the predominance of higher modes in our observations. The excitation of higher modes is key element of explanation for the long duration and amplification of the seismic signals observed in the Valley of Mexico.

  11. Combining NMR spectral and structural data to form models of polychlorinated dibenzodioxins, dibenzofurans, and biphenyls binding to the AhR

    NASA Astrophysics Data System (ADS)

    Beger, Richard D.; Buzatu, Dan A.; Wilkes, Jon G.

    2002-10-01

    A three-dimensional quantitative spectrometric data-activity relationship (3D-QSDAR) modeling technique which uses NMR spectral and structural information that is combined in a 3D-connectivity matrix has been developed. A 3D-connectivity matrix was built by displaying all possible assigned carbon NMR chemical shifts, carbon-to-carbon connections, and distances between the carbons. Two-dimensional 13C-13C COSY and 2D slices from the distance dimension of the 3D-connectivity matrix were used to produce a relationship among the 2D spectral patterns for polychlorinated dibenzofurans, dibenzodioxins, and biphenyls (PCDFs, PCDDs, and PCBs respectively) binding to the aryl hydrocarbon receptor (AhR). We refer to this technique as comparative structural connectivity spectral analysis (CoSCoSA) modeling. All CoSCoSA models were developed using forward multiple linear regression analysis of the predicted 13C NMR structure-connectivity spectral bins. A CoSCoSA model for 26 PCDFs had an explained variance (r2) of 0.93 and an average leave-four-out cross-validated variance (q4 2) of 0.89. A CoSCoSA model for 14 PCDDs produced an r2 of 0.90 and an average leave-two-out cross-validated variance (q2 2) of 0.79. One CoSCoSA model for 12 PCBs gave an r2 of 0.91 and an average q2 2 of 0.80. Another CoSCoSA model for all 52 compounds had an r2 of 0.85 and an average q4 2 of 0.52. Major benefits of CoSCoSA modeling include ease of development since the technique does not use molecular docking routines.

  12. Structure, thermal and spectral study of 16α,17-epoxypregn-4-ene-3,11,20-trione monohydate

    NASA Astrophysics Data System (ADS)

    Nie, Qiang; Wang, JingKang

    2005-10-01

    16α,17-epoxypregn-4-ene-3,11,20-trione is an important steroid intermediate in synthesis of many hormone pharmaceuticals, such as cortisone acetate and betamethason. It does not dissolve in water, but the single crystals grown from acetone with some water shows evident hydration behavior. The thermal analyses by DSC and TG-DTA and the IR spectra characterization of the anhydrous and hydrous crystals were performed and compared. The hydrate was also proved by IR spectral and thermal analyses. Single crystal structure of the hydrate indicates one water molecule per host molecule is included into the host lattice. The incorporation of water molecules does not change the crystal cell dimensions significantly, except for some increment of the cell along the axis b. In the crystal cell, two steroid molecules are linked through the water molecules as a bridge by forming two different hydrogen bonds. The incorporation of one water molecule makes some conformation changes of the molecules in the crystal unit cell.

  13. [Comparative analysis of spatial organization of myoglobins. II. Secondary structure].

    PubMed

    Korobov, V N; Nazarenko, V I; Radomskiĭ, N F; Starodub, N F

    1992-01-01

    An analysis of probability of distribution curves of alpha-helical sites and bends of polypeptide chains of myoglobins in half-water mammals (beaver, nutria, muskrat, otter) carried out in comparison with those of myoglobins of the horse and Sperm whale (X-ray diffraction analysis has revealed their tertiary structure) has revealed a coincidence of the secondary structure sites end bends of the chain in the studied respiratory hemoproteins of muscles. Despite a considerable number of amino acid substitutions the profiles of alpha-helicity and B-bends of the compared proteins are practically identical. This indicates to the "resistance" of the probability curves to amino acid substitutions and to retention of the tertiary structure of myoglobins in evolutionary remote species of the animals.

  14. Control of spectral interference patterns in broad Rabi sidebands toward quasi-comb structures.

    PubMed

    Romanov, D A; Filin, A I; Levis, R J

    2015-03-01

    The pattern of spectral interference fringes in broad dynamic Rabi sidebands allows for a considerable degree of control by shaping the picosecond driving pulse. We demonstrate experimental evidence of such control and report an analytic and numerical investigation of possibilities to control the fringe pattern to produce a comb-like optical structure. The temporal phase and amplitude shaping of a picosecond driving pulse influence the spectrum envelope, fringe contrast, and fringe spacing variation in the sideband spectra. The sideband spectrum envelope depends on the sharpness of the driving pulse, that is, on the rate at which the temporal distance between the leading and trailing edges grows away from the pulse maximum. Increasing this parameter reduces the variation of the envelope amplitude across the sideband. The fringe contrast, defined by the maximum-to-minimum difference, depends strongly on the asymmetry of the driving pulse. The imbalance between the leading and trailing edges leads to a decrease of the contrast. The variation of interpeak distance within a sideband was controlled using the temporal shape of the driving pulse. In the particular case of a blue-shifted sideband emitted by excited oxygen atoms driven by a picosecond pulse of 800 nm carrier wavelength and ∼5×10¹⁰ W cm⁻² intensity, a Gaussian pulse shape results in an interpeak distance increasing almost five times over the interval from 1.60 to 1.66 eV, whereas a super-Gaussian shape leads to almost equidistant fringes producing a comb-like spectrum.

  15. Synthesis, structure, and spectral and electrochemical properties of chromium(III) tris-(8-hydroxyquinolinate).

    PubMed

    Freitas, Ana R; Silva, Mónica; Ramos, M Luísa; Justino, Licínia L G; Fonseca, Sofia M; Barsan, Madalina M; Brett, Christopher M A; Silva, M Ramos; Burrows, Hugh D

    2015-07-07

    The kinetically inert chromium(III) tris-(8-hydroxyquinolinate), Crq3, has been synthesized, crystallized from 90% methanol-water, and characterized by MALDI-TOF mass spectrometry, thermogravimetry, FTIR, NMR spectroscopy, and X-ray powder diffraction. It is formed as a methanol solvate, but the solvent can be removed by heating. Large paramagnetic shifts and spectral broadening in (1)H NMR spectra indicate electron delocalization between the metal and the ligand. DFT calculations show it is present as the meridional isomer, with the HOMO largely based on one of the metal 3d orbitals and the LUMO essentially localized on the ligands. Cyclic voltammetry (CV) in acetonitrile solutions shows four oxidation peaks and two, less intense reduction waves on the first scan. The HOMO energy determined from the first oxidation peak is fairly close to that obtained by DFT, in agreement with this being mainly metal based. Although the number of peaks decreases on subsequent CV scans, the complex shows markedly enhanced electrochemical stability compared with aluminium(III) tris-(8-hydroxyquinolinate). Solution UV/visible absorption and solid diffuse reflectance spectra have a weak, long wavelength band, assigned to the metal based d-d transition, in addition to the normal, ligand based bands seen in metal quinolates. The energy of the lowest energy band is identical to the HOMO-LUMO separation obtained by cyclic voltammetry, in agreement with the above description. The compound is only weakly luminescent, in contrast to many other metal quinolates, due to the lowest energy transition being metal rather than ligand based. The potential of this compound as an electron transporting/hole blocking layer in optoelectronic devices is indicated.

  16. Change in Drusen Area Over Time Compared Using Spectral-Domain Optical Coherence Tomography and Color Fundus Imaging

    PubMed Central

    Gregori, Giovanni; Yehoshua, Zohar; Garcia Filho, Carlos Alexandre de Amorim; Sadda, SriniVas R.; Portella Nunes, Renata; Feuer, William J.; Rosenfeld, Philip J.

    2014-01-01

    Purpose. To investigate the relationship between drusen areas measured with color fundus images (CFIs) and those with spectral-domain optical coherence tomography (SDOCT). Methods. Forty-two eyes from thirty patients with drusen in the absence of geographic atrophy were recruited to a prospective study. Digital color fundus images and SDOCT images were obtained at baseline and at follow-up visits at 3 and 6 months. Registered, matched circles centered on the fovea with diameters of 3 mm and 5 mm were identified on both CFIs and SDOCT images. Spectral-domain OCT drusen measurements were obtained using a commercially available proprietary algorithm. Drusen boundaries on CFIs were traced manually at the Doheny Eye Institute Image Reading Center. Results. Mean square root drusen area (SQDA) measurements for the 3-mm circles on the SDOCT images were 1.451 mm at baseline and 1.464 mm at week 26, whereas the measurements on CFIs were 1.555 mm at baseline and 1.584 mm at week 26. Mean SQDA measurements from CFIs were larger than those from the SDOCT measurements at all time points (P = 0.004 at baseline, P = 0.003 at 26 weeks). Changes in SQDA over 26 weeks measured with SDOCT were not different from those measured with CFIs (mean difference = 0.014 mm, P = 0.5). Conclusions. Spectral-domain OCT drusen area measurements were smaller than the measurements obtained from CFIs. However, there were no differences in the change in drusen area over time between the two imaging modalities. Spectral-domain OCT measurements were considerably more sensitive in assessing drusen area changes. PMID:25335982

  17. Rocket experiments for spectral estimation of electron density fine structure in the auroral and equatorial ionosphere and preliminary results

    NASA Technical Reports Server (NTRS)

    Tomei, B. A.; Smith, L. G.

    1986-01-01

    Sounding rockets equipped to monitor electron density and its fine structure were launched into the auroral and equatorial ionosphere in 1980 and 1983, respectively. The measurement electronics are based on the Langmuir probe and are described in detail. An approach to the spectral analysis of the density irregularities is addressed and a software algorithm implementing the approach is given. Preliminary results of the analysis are presented.

  18. Discovery of Spatial and Spectral Structure in the X-Ray Emission from the Crab Nebula.

    PubMed

    Weisskopf; Hester; Tennant; Elsner; Schulz; Marshall; Karovska; Nichols; Swartz; Kolodziejczak; O'Dell

    2000-06-20

    The Chandra X-Ray Observatory observed the Crab Nebula and pulsar during orbital calibration. Zeroth-order images with the High-Energy Transmission Grating (HETG) readout by the Advanced CCD Imaging Spectrometer spectroscopy array (ACIS-S) show a striking richness of X-ray structure at a resolution comparable to that of the best ground-based visible-light observations. The HETG-ACIS-S images reveal, for the first time, an X-ray inner ring within the X-ray torus, the suggestion of a hollow-tube structure for the torus, and X-ray knots along the inner ring and (perhaps) along the inward extension of the X-ray jet. Although complicated by instrumental effects and the brightness of the Crab Nebula, the spectrometric analysis shows systematic variations of the X-ray spectrum throughout the nebula.

  19. Discovery of Spatial and Spectral Structure in the X-Ray Emission from the Crab Nebula

    NASA Technical Reports Server (NTRS)

    Weisskopf, Martin C.; Hester, J. Jeff; Tennant, Allyn F.; Elsner, Ronald F.; Schulz, Norbert S.; Marshall, Herman L.; Karovska, Margarita; Nichols, Joy S.; Swartz, Douglas A.; Kolodziejczak, Jeffery J.

    2000-01-01

    The Chandra X-Ray Observatory observed the Crab Nebula and pulsar during orbital calibration. Zeroth-order images with the High-Energy Transmission Grating (HETG) readout by the Advanced Charge Coupled Devices (CCD) Imaging Spectrometer spectroscopy array (ACIS-S) show a striking richness of X-ray structure at a resolution comparable to that of the best ground-based visible-light observations. The HETG-ACIS-S images reveal, for the first time, an X-ray inner ring within the X-ray torus, the suggestion of a hollow-tube structure for the torus, and X-ray knots along the inner ring and (perhaps) along the inward extension of the X-ray jet. Although complicated by instrumental effects and the brightness of the Crab Nebula, the spectrometric analysis shows systematic variations of the X-ray spectrum throughout the nebula.

  20. A comparative structural study of wet and dried ettringite

    SciTech Connect

    Renaudin, G.; Filinchuk, Y.; Neubauer, J.; Goetz-Neunhoeffer, F.

    2010-03-15

    Two different techniques were used to compare structural characteristics of 'wet' ettringite (stored in the synthesis mother liquid) and 'dried' ettringite (dried to 35% relative humidity over saturated CaCl{sub 2} solution). Lattice parameters and the water content in the channel region of the structure (site occupancy factor of the water molecule not bonded to cations) as well as microstructure parameters (size and strain) were determined from a Rietveld refinement on synchrotron powder diffraction data. Local environment of sulphate anions and of the hydrogen bonding network was characterized by Raman spectroscopy. Both techniques led to the same conclusion: the 'wet' ettringite sample immersed in the mother solution from the synthesis presents similar structural features as ettringite dried to 35% relative humidity. An increase of the a lattice parameter combined with a decrease of the c lattice parameter occurs on drying. The amount of structural water, the point symmetry of sulphate and the hydrogen bond network are unchanged when passing from the wet to the dried ettringite powder. Ettringite does not form a high-hydrate polymorph in equilibrium with alkaline solution, in contrast to the AFm phases that lose water molecules on drying. According to these results we conclude that ettringite precipitated in aqueous solution at the early hydration stages is of the same chemical composition as ettringite present in the hardening concrete.

  1. Limitations of spectral measures and observations of the group structure of surface waves

    NASA Technical Reports Server (NTRS)

    Mollo-Christensen, Erik

    1987-01-01

    Wave-group structure, which plays a significant role in flux processes and the mechanics of the transfer of wave energy and momentum to the mean current field, is studied. The origin of wave groups, in particular sideband instabilities, the effects of amplitude variations on wave frequency and of wave damping on isolated groups, and flow separation over waves, is discussed. The mechanisms that cause the group formation are compared to the dynamics that result in wave propagation. The bifurcation and shift in wave modulations, and the possible existence of a unique asymptotic statistical state for the wave-modulation field are examined.

  2. Accurate modeling of spectral fine-structure in Earth radiance spectra measured with the Global Ozone Monitoring Experiment.

    PubMed

    van Deelen, Rutger; Hasekamp, Otto P; Landgraf, Jochen

    2007-01-10

    We present what we believe to be a novel approach to simulating the spectral fine structure (<1 nm) in measurements of spectrometers such as the Global Ozone Monitoring Experiment (GOME). GOME measures the Earth's radiance spectra and daily solar irradiance spectra from which a reflectivity spectrum is commonly extracted. The high-frequency structures contained in such a spectrum are, apart from atmospheric absorption, caused by Raman scattering and by a shift between the solar irradiance and the Earth's radiance spectrum. Normally, an a priori high-resolution solar spectrum is used to simulate these structures. We present an alternative method in which all the required information on the solar spectrum is retrieved from the GOME measurements. We investigate two approaches for the spectral range of 390-400 nm. First, a solar spectrum is reconstructed on a fine spectral grid from the GOME solar measurement. This approach leads to undersampling errors of up to 0.5% in the modeling of the Earth's radiance spectra. Second, a combination of the solar measurement and one of the Earth's radiance measurement is used to retrieve a solar spectrum. This approach effectively removes the undersampling error and results in residuals close to the GOME measurement noise of 0.1%.

  3. A correlational method to concurrently measure envelope and temporal fine structure weights: effects of age, cochlear pathology, and spectral shaping.

    PubMed

    Fogerty, Daniel; Humes, Larry E

    2012-09-01

    The speech signal may be divided into spectral frequency-bands, each band containing temporal properties of the envelope and fine structure. This study measured the perceptual weights for the envelope and fine structure in each of three frequency bands for sentence materials in young normal-hearing listeners, older normal-hearing listeners, aided older hearing-impaired listeners, and spectrally matched young normal-hearing listeners. The availability of each acoustic property was independently varied through noisy signal extraction. Thus, the full speech stimulus was presented with noise used to mask six different auditory channels. Perceptual weights were determined by correlating a listener's performance with the signal-to-noise ratio of each acoustic property on a trial-by-trial basis. Results demonstrate that temporal fine structure perceptual weights remain stable across the four listener groups. However, a different weighting typography was observed across the listener groups for envelope cues. Results suggest that spectral shaping used to preserve the audibility of the speech stimulus may alter the allocation of perceptual resources. The relative perceptual weighting of envelope cues may also change with age. Concurrent testing of sentences repeated once on a previous day demonstrated that weighting strategies for all listener groups can change, suggesting an initial stabilization period or susceptibility to auditory training.

  4. Comparative population structure of cavity-nesting sea ducks

    USGS Publications Warehouse

    Pearce, John M.; Eadie, John M.; Savard, Jean-Pierre L.; Christensen, Thomas K.; Berdeen, James; Taylor, Eric J.; Boyd, Sean; Einarsson, Árni

    2014-01-01

    A growing collection of mtDNA genetic information from waterfowl species across North America suggests that larger-bodied cavity-nesting species exhibit greater levels of population differentiation than smaller-bodied congeners. Although little is known about nest-cavity availability for these species, one hypothesis to explain differences in population structure is reduced dispersal tendency of larger-bodied cavity-nesting species due to limited abundance of large cavities. To investigate this hypothesis, we examined population structure of three cavity-nesting waterfowl species distributed across much of North America: Barrow's Goldeneye (Bucephala islandica), Common Goldeneye (B. clangula), and Bufflehead (B. albeola). We compared patterns of population structure using both variation in mtDNA control-region sequences and band-recovery data for the same species and geographic regions. Results were highly congruent between data types, showing structured population patterns for Barrow's and Common Goldeneye but not for Bufflehead. Consistent with our prediction, the smallest cavity-nesting species, the Bufflehead, exhibited the lowest level of population differentiation due to increased dispersal and gene flow. Results provide evidence for discrete Old and New World populations of Common Goldeneye and for differentiation of regional groups of both goldeneye species in Alaska, the Pacific Northwest, and the eastern coast of North America. Results presented here will aid management objectives that require an understanding of population delineation and migratory connectivity between breeding and wintering areas. Comparative studies such as this one highlight factors that may drive patterns of genetic diversity and population trends.

  5. Crystal structures of the F88Y obelin mutant before and after bioluminescence provide molecular insight into spectral tuning among hydromedusan photoproteins.

    PubMed

    Natashin, Pavel V; Markova, Svetlana V; Lee, John; Vysotski, Eugene S; Liu, Zhi-Jie

    2014-03-01

    Ca(2+) -regulated photoproteins are responsible for the bioluminescence of a variety of marine coelenterates. All hydromedusan photoproteins are a single-chain polypeptide to which 2-hydroperoxycoelenterazine is tightly but non-covalently bound. Bioluminescence results from oxidative decarboxylation of 2-hydroperoxycoelenterazine, generating protein-bound coelenteramide in an excited state. The bioluminescence spectral maxima of recombinant photoproteins vary in the range 462-495 nm, despite a high degree of identity of amino acid sequences and spatial structures of these photoproteins. Based on studies of obelin and aequorin mutants with substitution of Phe to Tyr and Tyr to Phe, respectively [Stepanyuk GA et al. (2005) FEBS Lett 579, 1008-1014], it was suggested that the spectral differences may be accounted for by an additional hydrogen bond between the hydroxyl group of a Tyr residue and an oxygen atom of the 6-(p-hydroxyphenyl) substituent of coelenterazine. Here, we report the crystal structures of two conformation states of the F88Y obelin mutant that has bioluminescence and product fluorescence spectra resembling those of aequorin. Comparison of spatial structures of the F88Y obelin conformation states with those of wild-type obelin clearly shows that substitution of Phe to Tyr does not affect the overall structures of either F88Y obelin or its product following Ca(2+) discharge, compared to the conformation states of wild-type obelin. The hydrogen bond network in F88Y obelin being due to the Tyr substitution clearly supports the suggestion that different hydrogen bond patterns near the oxygen of the 6-(p-hydroxyphenyl) substituent are the basis for spectral modifications between hydromedusan photoproteins.

  6. Molecular structure and spectral investigations of 3,5-Di-tert-butyl-o-benzoquinone

    NASA Astrophysics Data System (ADS)

    Yilmaz, M.; Aydin, B.; Dogan, O.; Dereli, O.

    2017-01-01

    Conformational analysis of 3,5-Di-tert-butyl-o-benzoquinone molecule was performed and two stable conformers were determined by B3LYP/6-311++G(d,p). Using the most stable one, molecular structural parameters, vibrational frequencies were calculated by B3LYP/6-311++G(d,p), B3LYP/6-31G(d) and BLYP/6-31G(d,p) levels of theory. The FT-IR spectrum of the compound was recorded in the region 4000-550 cm-1. The Raman spectrum was also recorded in the region 3500-100 cm-1. Calculated results were compared with experimental counterparts. The best results were obtained from B3LYP/6-311++G(d,p) calculations. Experimental 13C and 1H NMR data of tittle compound were taken from literature and the calculated results compared with these data. Vibrational and NMR band assignments were performed. HOMO-LUMO energies, molecular electrostatic potentials and thermodynamic properties were also given for further investigations of our structure.

  7. Least-Squares Regression and Spectral Residual Augmented Classical Least-Squares Chemometric Models for Stability-Indicating Analysis of Agomelatine and Its Degradation Products: A Comparative Study.

    PubMed

    Naguib, Ibrahim A; Abdelrahman, Maha M; El Ghobashy, Mohamed R; Ali, Nesma A

    2016-01-01

    Two accurate, sensitive, and selective stability-indicating methods are developed and validated for simultaneous quantitative determination of agomelatine (AGM) and its forced degradation products (Deg I and Deg II), whether in pure forms or in pharmaceutical formulations. Partial least-squares regression (PLSR) and spectral residual augmented classical least-squares (SRACLS) are two chemometric models that are being subjected to a comparative study through handling UV spectral data in range (215-350 nm). For proper analysis, a three-factor, four-level experimental design was established, resulting in a training set consisting of 16 mixtures containing different ratios of interfering species. An independent test set consisting of eight mixtures was used to validate the prediction ability of the suggested models. The results presented indicate the ability of mentioned multivariate calibration models to analyze AGM, Deg I, and Deg II with high selectivity and accuracy. The analysis results of the pharmaceutical formulations were statistically compared to the reference HPLC method, with no significant differences observed regarding accuracy and precision. The SRACLS model gives comparable results to the PLSR model; however, it keeps the qualitative spectral information of the classical least-squares algorithm for analyzed components.

  8. Comparing the spectral lag of short and long gamma-ray bursts and its relation with the luminosity

    NASA Astrophysics Data System (ADS)

    Bernardini, M. G.; Ghirlanda, G.; Campana, S.; Covino, S.; Salvaterra, R.; Atteia, J.-L.; Burlon, D.; Calderone, G.; D'Avanzo, P.; D'Elia, V.; Ghisellini, G.; Heussaff, V.; Lazzati, D.; Melandri, A.; Nava, L.; Vergani, S. D.; Tagliaferri, G.

    2015-01-01

    We investigated the rest-frame spectral lags of two complete samples of bright long (50) and short (6) gamma-ray bursts (GRB) detected by Swift. We analysed the Swift/Burst Alert Telescope data through a discrete cross-correlation function fitted with an asymmetric Gaussian function to estimate the lag and the associated uncertainty. We find that half of the long GRBs have a positive lag and half a lag consistent with zero. All short GRBs have lags consistent with zero. The distributions of the spectral lags for short and long GRBs have different average values. Limited by the small number of short GRBs, we cannot exclude at more than 2σ significance level that the two distributions of lags are drawn from the same parent population. If we consider the entire sample of long GRBs, we do not find evidence for a lag-luminosity correlation, rather the lag-luminosity plane appears filled on the left-hand side, thus suggesting that the lag-luminosity correlation could be a boundary. Short GRBs are consistent with the long ones in the lag-luminosity plane.

  9. Vibrational and structural observations upon 3-((1H-benzo[d]imidazol-1-yl)methyl)naphthalen-2-ol from spectral and DFT computing approaches

    NASA Astrophysics Data System (ADS)

    Jone Pradeepa, S.; Tamilvendan, D.; Susai Boobalan, Maria; Sundaraganesan, N.

    2016-05-01

    An aggregate of experimental and computational study on synthesis, molecular structure, vibrational, electronic, nuclear magnetic resonance spectra, electronic structure, NLO activity and thermochemical characterization has been investigated for 3-((1H-benzo[d]imidazol-1-yl)methyl) naphthalen-2-ol (BDMN). The perspective on structural analysis includes the examination of equilibrium geometry, Natural Bond Orbital analysis (NBO), molecular electrostatic potential (MEP) analysis and frontier molecular orbital calculation. Similarly the following spectral analysis such as vibrational (FT-IR and FT-Raman), electronic (UV-Vis) and NMR (1H and 13C) has been interpreted. The FT-IR, FT-Raman spectrum were recorded in the frequency range of 4000-400 cm-1 and 4000-50 cm-1 respectively. A complete potential energy distribution (PED) was achieved to interpret the normal modes by comparing the experimental and theoretical spectral data. The simulation of NMR spectrum was performed using GIAO strategy. The NLO activity of BDMN has been calibrated using hyperpolarizability. In addition, various thermodynamic entities were predicted against different temperatures. The entire computation was executed using appropriate model chemistries such as B3LYP/Sadlej pVTZ, B3LYP/6-311G(d,p) and PBEPBE (TDDFT)/6-311G(d,p) for the respective properties. The overall hand-in-hand analysis by using both theoretical and experimental calculation on BDMN provides interesting observations and inferences.

  10. Comparative Structure of Saturn's Rings from Cassini Radio Occultation Observations

    NASA Astrophysics Data System (ADS)

    Marouf, Essam A.; French, R. G.; Rappaport, N. J.; McGhee, C. A.; Wong, K.; Thomson, F. S.; Anabtawi, A.

    2007-10-01

    Radio occultations of Saturn's rings during the Cassini prime mission fall into three main groups, depending on the rings opening angle B. The first is a set of eight diametric occultations completed early in the mission (March-September/2005) when |B| was relatively large (19.5 to 23.5°). They permitted multiple-longitude profiling of relatively optically thick ring features, revealing detailed structure of enigmatic Ring B. The second is to be completed late in the mission when the rings are relatively closed (|B| < 10°). They will provide enhanced sensitivity to tenuous ring material, hence complementary information about small optical depth structure. Bridging the two groups is a third composed of two specially designed occultations recently completed (May-June/2007). They capture the intermediate range |B| 15°. Because the rings were still reasonably open, much of the structure was profiled. The different occultation geometry from the diametric group provided enhanced sensitivity to bending waves and other inclined features. We comparatively consider variability (or lack of) of observed ring structure with B and longitude. The variability when present can be true (dynamically forced features) or apparent (azimuthal asymmetry due to preferentially aligned gravitational wakes). The multiple-longitude coverage provides rich characterization of the true variability, including remarkable variations in the morphology of gap-embedded ringlets in Ring C, clear variations in the width of gaps in the Cassini Division, wavelike features in Ring C (the "Rosen Waves"), classical satellite wake profiles due to Pan, in addition to many density and few bending waves. For the apparent asymmetry, observed optical depth variations with B, viewing geometry, and wavelength constrain physical properties of the rings microstructure (particle sizes, particle-cluster sizes and orientation, spatial cluster density, vertical ring profile and physical thickness, ...). Complementary

  11. Comparing and distinguishing the structure of biological branching.

    PubMed

    Lamberton, Timothy O; Lefevre, James; Short, Kieran M; Smyth, Ian M; Hamilton, Nicholas A

    2015-01-21

    Bifurcating developmental branching morphogenesis gives rise to complex organs such as the lung and the ureteric tree of the kidney. However, a few quantitative methods or tools exist to compare and distinguish, at a structural level, the critical features of these important biological systems. Here we develop novel graph alignment techniques to quantify the structural differences of rooted bifurcating trees and demonstrate their application in the analysis of developing kidneys from in normal and mutant mice. We have developed two graph based metrics: graph discordance, which measures how well the graphs representing the branching structures of distinct trees graphs can be aligned or overlayed; and graph inclusion, which measures the degree of containment of a tree graph within another. To demonstrate the application of these approaches we first benchmark the discordance metric on a data set of 32 normal and 28Tgfβ(+/-) mutant mouse ureteric trees. We find that the discordance metric better distinguishes control and mutant mouse kidneys than alternative metrics based on graph size and fingerprints - the distribution of tip depths. Using this metric we then show that the structure of the mutant trees follows the same pattern as the normal kidneys, but undergo a major delay in elaboration at later stages. Analysis of both controls and mutants using the inclusion metric gives strong support to the hypothesis that ureteric tree growth is stereotypic. Additionally, we present a new generalised multi-tree alignment algorithm that minimises the sum of pairwise graph discordance and which can be used to generate maximum consensus trees that represent the archetype for fixed developmental stages. These tools represent an advance in the analysis and quantification of branching patterns and will be invaluable in gaining a deeper understanding of the mechanisms that drive development. All code is being made available with documentation and example data with this publication.

  12. Molecular structure and spectral (FT-IR, Raman) investigations of 3-aminocoumarin

    NASA Astrophysics Data System (ADS)

    Dereli, Ömer

    2016-05-01

    The molecular structure of 3-Aminocoumarin was determined by conformational analysis. Conformational space was scanned by conformer distribution option of Spartan 08 program package using Merck Molecular Force Field (MMFF) method. Then obtained conformers were optimized by B3LYP/6-311++ G( d, p) and B3LYP/6-311 G( d, p) levels of Density Functional Theory. As a result of these calculations, only one conformer was determined. Vibrational frequencies of this conformer were calculated by Gaussian 03 program package using the same levels of geometry optimizations. The FT-IR and Raman spectra of 3-Aminocoumarin were recorded and compared with the calculated values. Consequently, a good agreement between experimental and the calculated values were founded. Molecular electrostatic potentials (MEPs), HOMO-LUMO energies, thermodynamic properties and Mulliken atomic charges were also covered in this study.

  13. Discovery of Spatial and Spectral Structure in the X-Ray Emission from the Crab Nebula

    NASA Technical Reports Server (NTRS)

    Weisskopf, M.; Hester, J. J.; Tennant, A. F.; Elsner, R. F.; Schulz, N. S.; Marshall, H. L.; Karovska, M.; Nichols, J. S.; Swartz, D. A.; Kolodziejczak, J. J.

    2000-01-01

    The Chandra X-ray Observatory observed the Crab Nebula and Pulsar During orbital calibration. Zeroth-order images with the High-Energy Transmission Grating (HETG) read-out by the Advanced CCD Imaging Spectrometer spectroscopy array (ACIS-S) show a striking richness of X-ray structure, at a resolution comparable to that of the best ground-based visible-light observations. The HETG-ACIS-S images reveal, for the first time, an X-ray knots along the inner ring and (perhaps) along the inward extension of the X-ray jet. Although complicated by instrumental effects and the brightness of the Crab Nebula, the spectrometric analysis shows systematic variations of the X-ray spectrum throughout the Nebula.

  14. Simulation studies for comparative evaluation of alternative spectral regions for the sensing of CO2 and O2 suitable for the ASCENDS Mission

    NASA Astrophysics Data System (ADS)

    Pliutau, Denis; Prasad, Narasimha S.

    2012-10-01

    We have carried out comparative simulation studies to establish the advantages and limitations of alternative spectral regions and measurement wavelengths being investigated by different groups for the sensing of CO2 and O2 for potential use in the ASCENDS mission implementation. Our studies are based on the lidar modeling framework we developed specifically for ASCENDS which may be further applied to similar missions relying on the active sensing approach from space or aircraft. The modeling framework performs standard lidar sensitivity calculations, and also includes analysis of weighting functions and the effects of laser wavelength instabilities. As such, the factors considered in the analysis include the general LIDAR sensitivity, shapes of the weighting functions, as well as the added error due to the laser wavelength jitter in the selected spectral bands and wavelength regions. In particular, the studies were performed for the 1.26 - 1.27 micron and the A-band of oxygen, as well as the 1.57 and 2.06 micron bands of carbon dioxide. Additionally, the analysis is based on a range of satellite datasets and models to also take into account a variety of spacial and temporal variations in surface and atmospheric parameters. The results of our comparative studies for alternative spectral bands will be presented including the quantitative estimates of required constraints on selected system parameters to achieve the desired accuracy of ~0.3% in XCO2 measurements.

  15. Data structure of search & compare (S&C) reservation protocol

    NASA Astrophysics Data System (ADS)

    Markovič, Miroslav; Dubovan, Jozef; Dado, Milan; Benedikovič, Daniel; Litvík, Ján.

    2012-01-01

    On the present time, the most used technology of core networks is Wavelength-division multiplexing (WDM) which save a lot of bandwidth of optical fiber. But in each node all optical signals must be converted into the electrical domain, processed and converted back into the optical domain. Result of all these steps is that the data spend in the node a lot of time. This time decreases total available bandwidth in the optical networks. One of the results is that we compose WDM nodes which represent hybrid system of switching and controlling. If we use out-of-band signalizing it is simpler to separate control head from the data. For effective control and transmission of data over the optical networks, the reservation protocols are needed in WDM/OBS4,5. In today's networks exist a lot of the protocols, which have their own advantages and disadvantages. For our investigation it was chosen the reservation protocol called Search & Compare (S &C)1, because it uses parallel-segment based and parallel link reservation. The structure of data will be designed from the point of view of wavelength for transmission channels, length of optical burst, source and group addresses in the segment, number of nodes and the total time needed for switching. Structure of the protocol will contain all of the control messages which are necessary for reservation a path along all segments. The design of the protocol follows the ITU-T recommendation2,3.

  16. Protein structure prediction provides comparable performance to crystallographic structures in docking-based virtual screening.

    PubMed

    Du, Hongying; Brender, Jeffrey R; Zhang, Jian; Zhang, Yang

    2015-01-01

    Structure based virtual screening has largely been limited to protein targets for which either an experimental structure is available or a strongly homologous template exists so that a high-resolution model can be constructed. The performance of state of the art protein structure predictions in virtual screening in systems where only weakly homologous templates are available is largely untested. Using the challenging DUD database of structural decoys, we show here that even using templates with only weak sequence homology (<30% sequence identity) structural models can be constructed by I-TASSER which achieve comparable enrichment rates to using the experimental bound crystal structure in the majority of the cases studied. For 65% of the targets, the I-TASSER models, which are constructed essentially in the apo conformations, reached 70% of the virtual screening performance of using the holo-crystal structures. A correlation was observed between the success of I-TASSER in modeling the global fold and local structures in the binding pockets of the proteins versus the relative success in virtual screening. The virtual screening performance can be further improved by the recognition of chemical features of the ligand compounds. These results suggest that the combination of structure-based docking and advanced protein structure modeling methods should be a valuable approach to the large-scale drug screening and discovery studies, especially for the proteins lacking crystallographic structures.

  17. Non-structural carbohydrates in woody plants compared among laboratories.

    PubMed

    Quentin, Audrey G; Pinkard, Elizabeth A; Ryan, Michael G; Tissue, David T; Baggett, L Scott; Adams, Henry D; Maillard, Pascale; Marchand, Jacqueline; Landhäusser, Simon M; Lacointe, André; Gibon, Yves; Anderegg, William R L; Asao, Shinichi; Atkin, Owen K; Bonhomme, Marc; Claye, Caroline; Chow, Pak S; Clément-Vidal, Anne; Davies, Noel W; Dickman, L Turin; Dumbur, Rita; Ellsworth, David S; Falk, Kristen; Galiano, Lucía; Grünzweig, José M; Hartmann, Henrik; Hoch, Günter; Hood, Sharon; Jones, Joanna E; Koike, Takayoshi; Kuhlmann, Iris; Lloret, Francisco; Maestro, Melchor; Mansfield, Shawn D; Martínez-Vilalta, Jordi; Maucourt, Mickael; McDowell, Nathan G; Moing, Annick; Muller, Bertrand; Nebauer, Sergio G; Niinemets, Ülo; Palacio, Sara; Piper, Frida; Raveh, Eran; Richter, Andreas; Rolland, Gaëlle; Rosas, Teresa; Saint Joanis, Brigitte; Sala, Anna; Smith, Renee A; Sterck, Frank; Stinziano, Joseph R; Tobias, Mari; Unda, Faride; Watanabe, Makoto; Way, Danielle A; Weerasinghe, Lasantha K; Wild, Birgit; Wiley, Erin; Woodruff, David R

    2015-11-01

    Non-structural carbohydrates (NSC) in plant tissue are frequently quantified to make inferences about plant responses to environmental conditions. Laboratories publishing estimates of NSC of woody plants use many different methods to evaluate NSC. We asked whether NSC estimates in the recent literature could be quantitatively compared among studies. We also asked whether any differences among laboratories were related to the extraction and quantification methods used to determine starch and sugar concentrations. These questions were addressed by sending sub-samples collected from five woody plant tissues, which varied in NSC content and chemical composition, to 29 laboratories. Each laboratory analyzed the samples with their laboratory-specific protocols, based on recent publications, to determine concentrations of soluble sugars, starch and their sum, total NSC. Laboratory estimates differed substantially for all samples. For example, estimates for Eucalyptus globulus leaves (EGL) varied from 23 to 116 (mean = 56) mg g(-1) for soluble sugars, 6-533 (mean = 94) mg g(-1) for starch and 53-649 (mean = 153) mg g(-1) for total NSC. Mixed model analysis of variance showed that much of the variability among laboratories was unrelated to the categories we used for extraction and quantification methods (method category R(2) = 0.05-0.12 for soluble sugars, 0.10-0.33 for starch and 0.01-0.09 for total NSC). For EGL, the difference between the highest and lowest least squares means for categories in the mixed model analysis was 33 mg g(-1) for total NSC, compared with the range of laboratory estimates of 596 mg g(-1). Laboratories were reasonably consistent in their ranks of estimates among tissues for starch (r = 0.41-0.91), but less so for total NSC (r = 0.45-0.84) and soluble sugars (r = 0.11-0.83). Our results show that NSC estimates for woody plant tissues cannot be compared among laboratories. The relative changes in NSC between treatments measured within a laboratory

  18. MO-F-CAMPUS-I-04: Characterization of Fan Beam Coded Aperture Coherent Scatter Spectral Imaging Methods for Differentiation of Normal and Neoplastic Breast Structures

    SciTech Connect

    Morris, R; Albanese, K; Lakshmanan, M; Greenberg, J; Kapadia, A

    2015-06-15

    Purpose: This study intends to characterize the spectral and spatial resolution limits of various fan beam geometries for differentiation of normal and neoplastic breast structures via coded aperture coherent scatter spectral imaging techniques. In previous studies, pencil beam raster scanning methods using coherent scatter computed tomography and selected volume tomography have yielded excellent results for tumor discrimination. However, these methods don’t readily conform to clinical constraints; primarily prolonged scan times and excessive dose to the patient. Here, we refine a fan beam coded aperture coherent scatter imaging system to characterize the tradeoffs between dose, scan time and image quality for breast tumor discrimination. Methods: An X-ray tube (125kVp, 400mAs) illuminated the sample with collimated fan beams of varying widths (3mm to 25mm). Scatter data was collected via two linear-array energy-sensitive detectors oriented parallel and perpendicular to the beam plane. An iterative reconstruction algorithm yields images of the sample’s spatial distribution and respective spectral data for each location. To model in-vivo tumor analysis, surgically resected breast tumor samples were used in conjunction with lard, which has a form factor comparable to adipose (fat). Results: Quantitative analysis with current setup geometry indicated optimal performance for beams up to 10mm wide, with wider beams producing poorer spatial resolution. Scan time for a fixed volume was reduced by a factor of 6 when scanned with a 10mm fan beam compared to a 1.5mm pencil beam. Conclusion: The study demonstrates the utility of fan beam coherent scatter spectral imaging for differentiation of normal and neoplastic breast tissues has successfully reduced dose and scan times whilst sufficiently preserving spectral and spatial resolution. Future work to alter the coded aperture and detector geometries could potentially allow the use of even wider fans, thereby making coded

  19. MWIR/LWIR filter based on Liquid-Crystal Fabry-Perot structure for tunable spectral imaging detection

    NASA Astrophysics Data System (ADS)

    Zhang, Huaidong; Muhammad, Afzal; Luo, Jun; Tong, Qing; Lei, Yu; Zhang, Xinyu; Sang, Hongshi; Xie, Changsheng

    2015-03-01

    An electrically tunable medium-wave infrared (MWIR)/long-wave infrared (LWIR) filter based on the key structure of Liquid-Crystal (LC) Fabry-Perot (FP), which works in the wavelength range from 2.5 μm to 12 μm, is designed and fabricated successfully in this paper. According to the optical interference principle of the FP cavity and electrically controlled birefringence of nematic LC molecules, the particular functions including spectral selection and spectral staring and spectral adjustment, can be realized by the developed MWIR/LWIR filter driven and controlled electrically. As to the LC-FP filter, both planar reflective mirrors are shaped by depositing a layer of aluminum (Al) film (∼60 nm) over one side of double-side polished Zinc Selenide (ZnSe) wafer (∼1 mm), and then polyimide (PI) layer with the thickness of ∼100 nm is coated directly on Al film. With typical sandwich architecture, the depth of the cavity with nematic LC molecules sealed in is ∼7.5 μm. To make sure the LC molecules parallel aligned and twist regularly under voltage driving signal applied on Al film, which also acts as electrode, the V-grooves are formed in PI layer with the depth of ∼90 nm and the width of ∼350 nm at average by strong rubbing. The typical transmission spectrum in MWIR&LWIR wavelength range and several spectral images in MWIR wavelength range based on the fabricated LC-FP filter, have been obtained through applying a voltage driving-signal with different root-means-square (RMS) value over the electrodes of LC-FP filter in the selected voltage range from 0VRMS to 19.8VRMS. The testing result demonstrates a prospect of realization smart spectral imaging and further integrating the LC-FP filter with infrared focal plane arrays (FPAs) to achieve the purpose infrared multispectral imaging. The developed MWIR&LWIR LC-FP filters show some obvious advantages such as wide working wavelength range, electrically tunable spectral selection, ultra-compact, low cost, being

  20. Structure, function and evolution of the gas exchangers: comparative perspectives

    PubMed Central

    Maina, JN

    2002-01-01

    Over the evolutionary continuum, animals have faced similar fundamental challenges of acquiring molecular oxygen for aerobic metabolism. Under limitations and constraints imposed by factors such as phylogeny, behaviour, body size and environment, they have responded differently in founding optimal respiratory structures. A quintessence of the aphorism that ‘necessity is the mother of invention’, gas exchangers have been inaugurated through stiff cost–benefit analyses that have evoked transaction of trade-offs and compromises. Cogent structural–functional correlations occur in constructions of gas exchangers: within and between taxa, morphological complexity and respiratory efficiency increase with metabolic capacities and oxygen needs. Highly active, small endotherms have relatively better-refined gas exchangers compared with large, inactive ectotherms. Respiratory structures have developed from the plain cell membrane of the primeval prokaryotic unicells to complex multifunctional ones ofthe modern Metazoa. Regarding the respiratory medium used to extract oxygen from, animal life has had only two choices – water or air – within the biological range of temperature and pressure the only naturally occurring respirable fluids. In rarer cases, certain animalshave adapted to using both media. Gills (evaginated gas exchangers) are the primordial respiratory organs: they are the archetypal water breathing organs. Lungs (invaginated gas exchangers) are the model air breathing organs. Bimodal (transitional) breathers occupy the water–air interface. Presentation and exposure of external (water/air) and internal (haemolymph/blood) respiratory media, features determined by geometric arrangement of the conduits, are important features for gas exchange efficiency: counter-current, cross-current, uniform pool and infinite pool designs have variably developed. PMID:12430953

  1. Spectral properties of optical pulse, containing a few cycles, reflected from or passed through disordered layered structure

    NASA Astrophysics Data System (ADS)

    Trofimov, Vyacheslav A.; Pedan, Eugeniy V.

    2016-04-01

    As it is well-known, THz TDS is a modern tool for the detection and identification of substance. Often, in real conditions a substance under identification is covered by various materials (paper sheet, napkins, rag, and et.al). Therefore, the identification occurs for a substance covered by disordered structure, which acts for THz radiation as disordered photonic structure. In standard THz TDS method the substance detection carries out using a comparison of spectrum of a substance under consideration with spectra of the substances from database. Thus, an investigation of spectral medium response covered by disordered structure is very important for security and screening problem. Moreover, what we will see if we analyze a response from disordered structure without any dangerous substance? This question is a key one for practical application. Using computer simulation, we investigate below a propagation of laser pulse with a few cycles in a linear layered structure with random fluctuation of either layer dielectric permittivity or layers thicknesses or both characteristics of this structure. The process under consideration is described by 1D Maxwell's equations. We show that a spectrum of pulse either reflected from substance or transmitted through substance depends in strong way from a number of random realization and fluctuating parameters of layered structure and an observer can see various absorption frequencies corresponding to dangerous substances. Nevertheless, we discuss one of possible ways for overcoming the influence of disordered structure on the observed spectrum.

  2. Influence of structural and solvation factors on the spectral-fluorescent properties of alkyl-substituted BODIPYs in solutions

    NASA Astrophysics Data System (ADS)

    Bumagina, Natalia A.; Antina, Elena V.; Berezin, Mikhail B.; Kalyagin, Alexander A.

    2017-02-01

    The spectral-fluorescent properties of alkyl-substituted BODIPYs 1-5 in organic solvents were investigated. The alkyl-substituted BODIPYs 1-5 exhibit intense chromophoric properties (lgε = 4.60-5.00). Relative fluorescence quantum yield of studied compounds reaches 66-100% and weakly dependent on the structural and solvation effects. Introduction of methyl, propyl, amyl and heptyl substituents in the 2,6-positions of the pyrroles the results in a significant red shift (22-29 nm) in the electronic absorption and fluorescence spectra.

  3. Study on the Response Coefficient of Setback Structures Compared to Regular Moment Frame Structures

    SciTech Connect

    Mirghaderi, S. Rasoul; Khafaf, Bardia; Epackachi, Siamak

    2008-07-08

    In design practice of many countries, seismic analysis and proportioning of structures are usually based upon linear elastic analysis due to reduced seismic forces by response coefficient; R. Setback structures are one of the most popular shapes of the constructed buildings. In setback structures, the shape and proportions of the building have a major effect on distribution of earthquake forces as they work their way through the building. On the other hand, geometric configuration has a profound effect on the structural-dynamic response of a building. Therefore, when a building has irregular features, such as asymmetric in height or vertical discontinuity, the traditional assumptions used in development of seismic criteria for regular buildings may not be applicable. Inelastic seismic behavior of these types of structures seems to be quite different from the regular steel moment resisting structures in which the overall ductility is localized at beam-ends.In order to investigate the seismic behavior and estimate the Response Coefficient of those structures, nonlinear static analysis (pushover) are used for three categories of setback structures namely low rise, medium rise and high rise buildings with different setbacks in their height. The Response Coefficient are calculated and compared with those taken from regular type of moment frame structures.

  4. Detecting molecular features of spectra mainly associated with structural and non-structural carbohydrates in co-products from bioEthanol production using DRIFT with uni- and multivariate molecular spectral analyses.

    PubMed

    Yu, Peiqiang; Damiran, Daalkhaijav; Azarfar, Arash; Niu, Zhiyuan

    2011-01-01

    spectra, but not wheat and wheat DDGS. This study indicated that the bioethanol processing changes carbohydrate molecular structural profiles, compared with the original grains. However, the sensitivities of different types of carbohydrates and different grains (corn and wheat) to the processing differ. In general, the bioethanol processing increases the molecular spectral intensities for the structural carbohydrates and decreases the intensities for the non-structural carbohydrates. Further study is needed to quantify carbohydrate related molecular spectral features of the bioethanol co-products in relation to nutrient supply and availability of carbohydrates.

  5. Detecting Molecular Features of Spectra Mainly Associated with Structural and Non-Structural Carbohydrates in Co-Products from BioEthanol Production Using DRIFT with Uni- and Multivariate Molecular Spectral Analyses

    PubMed Central

    Yu, Peiqiang; Damiran, Daalkhaijav; Azarfar, Arash; Niu, Zhiyuan

    2011-01-01

    DDGS molecular spectra, but not wheat and wheat DDGS. This study indicated that the bioethanol processing changes carbohydrate molecular structural profiles, compared with the original grains. However, the sensitivities of different types of carbohydrates and different grains (corn and wheat) to the processing differ. In general, the bioethanol processing increases the molecular spectral intensities for the structural carbohydrates and decreases the intensities for the non-structural carbohydrates. Further study is needed to quantify carbohydrate related molecular spectral features of the bioethanol co-products in relation to nutrient supply and availability of carbohydrates. PMID:21673931

  6. Synthesis, structural, spectral, electrochemical and catalytic properties of VO (IV) complexes containing N, O donors

    NASA Astrophysics Data System (ADS)

    Kanmani Raja, K.; Lekha, L.; Hariharan, R.; Easwaramoorthy, D.; Rajagopal, G.

    2014-10-01

    Complexes of the general formula M (X-DPMP)2 [where, (M = VOIV), DPMP = 2-[(2,6-Diisopropyl-phenylimino)-methyl]-phenol and X = Br, BrCl, Ph] have been synthesized and characterized by IR, electronic, ESR spectral, magnetic and cyclic voltammetry measurements. The newly synthesized Schiff bases act as monobasic bidentate ligand in their complexes. The spectral data indicate that the ligand coordinates through the phenolic oxygen and azomethine nitrogen atoms. The observed parameters, hyperfine splitting constant (A) and Landé splitting energy (g) are found to be in good agreement with the values generally observed for the vanadyl complex with square pyramidal geometry. The cyclic voltammetric redox potentials of VO (IV) complexes suggest the existence of irreversible pairs in acetonitrile. The vanadium complexes were screened for sulfide oxidation studies and VO (C19H21BrON)2 or [VO (Br-DPMP)2] was found to be an efficient catalyst for the oxidation of various sulfides to sulfoxides with PhIO terminal oxidant. Both aryl and alkyl sulfides were selected and converted into sulfoxides in good to excellent yields.

  7. Spectral and polarization structure of field-induced photonic bands in cholesteric liquid crystals

    NASA Astrophysics Data System (ADS)

    Palto, S. P.; Barnik, M. I.; Geivandov, A. R.; Kasyanova, I. V.; Palto, V. S.

    2015-09-01

    Transmission of planar layers of cholesteric liquid crystals is studied in pulsed electric fields perpendicular to the helix axis at normal incidence of both linearly polarized and unpolarized light. Spectral and light polarization properties of the primary photonic band and the field-induced bands up to fourth order of Bragg selective reflection are studied in detail. In our experiments we have achieved an electric field strength several times higher than the theoretical values corresponding to the critical field of full helix unwinding. However, the experiments show that despite the high strength of the electric field applied the helix does not unwind, but strongly deforms, keeping its initial spatial period. Strong helix deformation results in distinct spectral band splitting, as well as very high field-induced selective reflectance that can be applied in lasers and other optoelectronic devices. Peculiarities of inducing and splitting the bands are discussed in terms of the scattering coefficient approach. All observed effects are confirmed by numerical simulations. The simulations also show that liquid crystal surface anchoring is not the factor that prevents the helix unwinding. Thus, the currently acknowledged concept of continuous helix unwinding in the electric field should be reconsidered.

  8. No-reference sharpness assessment of camera-shaken images by analysis of spectral structure.

    PubMed

    Oh, Taegeun; Park, Jincheol; Seshadrinathan, Kalpana; Lee, Sanghoon; Bovik, Alan Conrad

    2014-12-01

    The tremendous explosion of image-, video-, and audio-enabled mobile devices, such as tablets and smart-phones in recent years, has led to an associated dramatic increase in the volume of captured and distributed multimedia content. In particular, the number of digital photographs being captured annually is approaching 100 billion in just the U.S. These pictures are increasingly being acquired by inexperienced, casual users under highly diverse conditions leading to a plethora of distortions, including blur induced by camera shake. In order to be able to automatically detect, correct, or cull images impaired by shake-induced blur, it is necessary to develop distortion models specific to and suitable for assessing the sharpness of camera-shaken images. Toward this goal, we have developed a no-reference framework for automatically predicting the perceptual quality of camera-shaken images based on their spectral statistics. Two kinds of features are defined that capture blur induced by camera shake. One is a directional feature, which measures the variation of the image spectrum across orientations. The second feature captures the shape, area, and orientation of the spectral contours of camera shaken images. We demonstrate the performance of an algorithm derived from these features on new and existing databases of images distorted by camera shake.

  9. Synthesis, structure, spectral and electrochemical properties of B(OR)2-smaragdyrin complexes.

    PubMed

    Kalita, Hemanta; Lee, Way-Zen; Ravikanth, Mangalampalli

    2013-10-28

    A series of B(OR)2-smaragdyrin complexes were synthesized by treating BF2-smaragdyrin complex with various aliphatic and aromatic alcohols in the presence of AlCl3 in CH2Cl2 at room temperature. The compounds are stable and characterized by various spectroscopic and electrochemical techniques. The X-ray structure solved for one of the B(OR)2-smaragdyrin complex showed that the macrocycle is planar and the boron atom is in tetrahedral geometry coordinated to two pyrrole nitrogens of the macrocycle and two oxygen atoms of the axial -OR groups. (1)H NMR studies indicated that the alkoxy or aryloxy groups present on the boron atom experience the macrocyclic ring current effect and appear in the up-field region. The absorption properties of B(OR)2-smaragdyrin complexes showed a strong absorption band at ~700 nm along with other absorption bands in the 450-650 nm region like BF2-smaragdyrin complex. Since B(OR)2-smaragdyrin complexes are electron rich due to the presence of electron rich alkoxy and aryloxy groups, the B(OR)2-smaragdyrin complexes are easier to oxidize but difficult to reduce compared to BF2-smaragdyrin. The B(OR)2-smaragdyrin complexes are found to be weakly fluorescent than BF2-smaragdyrin.

  10. Inferring planar disorder in close-packed structures via ε-machine spectral reconstruction theory: examples from simulated diffraction patterns.

    PubMed

    Varn, D P; Canright, G S; Crutchfield, J P

    2013-07-01

    A previous paper detailed a novel algorithm, ε-machine spectral reconstruction theory (εMSR), that infers pattern and disorder in planar-faulted, close-packed structures directly from X-ray diffraction patterns [Varn et al. (2013). Acta Cryst. A69, 197-206]. Here εMSR is applied to simulated diffraction patterns from four close-packed crystals. It is found that, for stacking structures with a memory length of three or less, εMSR reproduces the statistics of the stacking structure; the result being in the form of a directed graph called an ε-machine. For stacking structures with a memory length larger than three, εMSR returns a model that captures many important features of the original stacking structure. These include multiple stacking faults and multiple crystal structures. Further, it is found that εMSR is able to discover stacking structure in even highly disordered crystals. In order to address issues concerning the long-range order observed in many classes of layered materials, several length parameters are defined, calculable from the ε-machine, and their relevance is discussed.

  11. The Hydrogen Epoch of Reionization Array Dish. II. Characterization of Spectral Structure with Electromagnetic Simulations and Its Science Implications.

    NASA Astrophysics Data System (ADS)

    Ewall-Wice, Aaron; Bradley, Richard; Deboer, David; Hewitt, Jacqueline; Parsons, Aaron; Aguirre, James; Ali, Zaki S.; Bowman, Judd; Cheng, Carina; Neben, Abraham R.; Patra, Nipanjana; Thyagarajan, Nithyanandan; Venter, Mariet; de Lera Acedo, Eloy; Dillon, Joshua S.; Dickenson, Roger; Doolittle, Phillip; Egan, Dennis; Hedrick, Mike; Klima, Patricia; Kohn, Saul; Schaffner, Patrick; Shelton, John; Saliwanchik, Benjamin; Taylor, H. A.; Taylor, Rusty; Tegmark, Max; Wirt, Butch

    2016-11-01

    We use time-domain electromagnetic simulations to determine the spectral characteristics of the Hydrogen Epoch of Reionization Arrays (HERA) antenna. These simulations are part of a multi-faceted campaign to determine the effectiveness of the dish’s design for obtaining a detection of redshifted 21 cm emission from the epoch of reionization. Our simulations show the existence of reflections between HERA’s suspended feed and its parabolic dish reflector that fall below -40 dB at 150 ns and, for reasonable impedance matches, have a negligible impact on HERA’s ability to constrain EoR parameters. It follows that despite the reflections they introduce, dishes are effective for increasing the sensitivity of EoR experiments at a relatively low cost. We find that electromagnetic resonances in the HERA feed’s cylindrical skirt, which is intended to reduce cross coupling and beam ellipticity, introduces significant power at large delays (-40 dB at 200 ns), which can lead to some loss of measurable Fourier modes and a modest reduction in sensitivity. Even in the presence of this structure, we find that the spectral response of the antenna is sufficiently smooth for delay filtering to contain foreground emission at line-of-sight wave numbers below k ∥ ≲ 0.2 h Mpc-1, in the region where the current PAPER experiment operates. Incorporating these results into a Fisher Matrix analysis, we find that the spectral structure observed in our simulations has only a small effect on the tight constraints HERA can achieve on parameters associated with the astrophysics of reionization.

  12. Alterations in the infrared spectral signature of avian feathers reflect potential chemical exposure: a pilot study comparing two sites in Pakistan.

    PubMed

    Llabjani, Valon; Malik, Riffat N; Trevisan, Júlio; Hoti, Valmira; Ukpebor, Justina; Shinwari, Zabta K; Moeckel, Claudia; Jones, Kevin C; Shore, Richard F; Martin, Francis L

    2012-11-01

    Chemical contamination of ecosystems is a global issue with evidence that pollutants impact on living organisms in a harmful fashion. Developing sensor approaches that would allow the derivation of biomarkers or signatures of effect in target sentinel organisms and monitor environmental chemical contamination in a high throughput manner is of utmost importance. As biomolecules absorb infrared (IR), signature vibrational spectra related to structure and function can be derived. In light of this, we tested the notion that IR spectra of bird feathers might reflect environmental chemical contaminant exposure patterns. Feathers were collected from monospecific heronries of cattle egret based in two independent locations (Trimu vs. Mailsi) in the Punjab province of Pakistan; these sites were found to differ in their chemical contamination patterns. Feather samples were chemically analyzed for polychlorinated biphenyls, polybrominated diphenyl ethers, organochlorines and heavy metals. Attenuated total reflection Fourier-transform IR (ATR-FTIR) spectroscopy was employed to derive a spectral signature of individual feathers. Resultant IR spectra were then subjected to canonical correspondence analysis (CAA) to determine whether feather spectral signatures correlate to chemical exposure. Additionally, we explored if principal component analysis (PCA) and linear discriminant analysis (LDA) could be applied to distinguish site-specific differences; linear discriminant function (LDF) was also applied to classify sites. The sampled feathers varied in their chemical exposure patterns depending on whether they were sourced from one site associated with heavy metal exposure or the other which suggested high organic pollutant exposures. CCA of chemical and spectral data showed a correlation between spectral signatures and chemical exposure. PCA-LDA readily distinguished feathers from the two different sites. Discriminating alterations were identified and these were associated with

  13. Electronic structure and spectral properties of terbium(III) nitrate complex with hexamethylphosphoramide.

    PubMed

    Kharchenko, Valerii I; Kurbatov, Ilya A; Cherednichenko, Alexander I; Mirochnik, Anatoly G; Zhikhareva, Polina A

    2017-03-05

    Spectral properties of terbium(III) nitrate complex with hexamethylphosphoramide have been studied by quantum-chemical methods within the density functional theory and methods of luminescent and X-ray photoelectron spectroscopy. Analysis of the luminescence excitation spectrum of the complex has indicated the absence of intramolecular transfer of electronic excitation energy from the ligand levels to the resonance levels of the rare earth central ion, so luminescence of the complex is associated with the electronic f-f-transitions of Tb(3+) ion (transitions (5)D4→(7)FJ, J=3-6). According to quantum-chemical modeling of the excited singlet and triplet levels of the complex, the excitation energy transfer from the ligands onto the central ion does not occur because of the significant difference of energies of their excited states.

  14. Electronic structure and spectral properties of terbium(III) nitrate complex with hexamethylphosphoramide

    NASA Astrophysics Data System (ADS)

    Kharchenko, Valerii I.; Kurbatov, Ilya A.; Cherednichenko, Alexander I.; Mirochnik, Anatoly G.; Zhikhareva, Polina A.

    2017-03-01

    Spectral properties of terbium(III) nitrate complex with hexamethylphosphoramide have been studied by quantum-chemical methods within the density functional theory and methods of luminescent and X-ray photoelectron spectroscopy. Analysis of the luminescence excitation spectrum of the complex has indicated the absence of intramolecular transfer of electronic excitation energy from the ligand levels to the resonance levels of the rare earth central ion, so luminescence of the complex is associated with the electronic f-f-transitions of Tb3 + ion (transitions 5D4 → 7FJ, J = 3-6). According to quantum-chemical modeling of the excited singlet and triplet levels of the complex, the excitation energy transfer from the ligands onto the central ion does not occur because of the significant difference of energies of their excited states.

  15. Spectrally-resolved Soft X-ray Observations and the Temperature Structure of the Solar Corona

    NASA Astrophysics Data System (ADS)

    Caspi, Amir; Warren, Harry; McTiernan, James; Woods, Thomas N.

    2015-04-01

    Solar X-ray observations provide important diagnostics of plasma heating and particle acceleration, during solar flares and quiescent periods. How the corona is heated to its ~1-3 MK nominal temperature remains one of the fundamental unanswered questions of solar physics; heating of plasma to tens of MK during solar flares -- particularly to the hottest observed temperatures of up to ~50 MK -- is also still poorly understood. Soft X-ray emission (~0.1-10 keV; or ~0.1-10 nm) is particularly sensitive to hot coronal plasma and serves as a probe of the thermal processes driving coronal plasma heating. Spectrally- and temporally-resolved measurements are crucial for understanding these energetic processes, but there have historically been very few such observations. We present new solar soft X-ray spectra from the Amptek X123-SDD, measuring quiescent solar X-ray emission from ~0.5 to ~30 keV with ~0.15 keV FWHM resolution from two SDO/EVE calibration sounding rocket underflights in 2012 and 2013. Combined with observations from RHESSI, GOES/XRS, SDO/EVE, and SDO/AIA, the temperature distribution derived from these data suggest significant hot (5-10 MK) emission from active regions, and the 2013 spectra suggest a low-FIP enhancement of only ~1.6 relative to the photosphere, 40% of the usually-observed value from quiescent coronal plasma. We explore the implications of these findings on coronal heating. We discuss future missions for spectrally-resolved soft X-ray observations using the X123-SDD, including the upcoming MinXSS 3U CubeSat using the X123-SDD and scheduled for deployment in mid-2015, and the CubIXSS 6U CubeSat mission concept.

  16. Non-invasive diagnostics of several structural and biophysical parameters of skin cover by spectral light reflectance

    NASA Astrophysics Data System (ADS)

    Ivanov, Arkady P.; Barun, Vladimir V.

    2007-05-01

    A calculation scheme and an algorithm to simultaneously diagnose several structural and biophysical parameters of skin by reflected light are constructed in the paper. The procedure is based the fact that, after absorption and scattering, light reflected by tissue contains information on its optically active chromophores and structure. The problem on isolating the desired parameters is a spectroscopic one under multiple scattering conditions. The latter considerably complicates the solution of the problem and requires the elaboration of an approach that is specific to the object studied. The procedure presented in the paper is based on spectral tissue model properties proposed earlier and engineering methods for solving the radiative transfer equation. The desired parameters are melanin and blood volume fractions, f and c, epidermis thickness d, mean diameter D of capillaries, and blood oxygenation degree S. Spectral diffuse reflectance R(λ) of skin over the range of 400 to 850 nm was calculated as a first stage. Then the sensitivity of R(λ) to the above parameters was studied to optimize the algorithm by wavelengths and to propose an experimental scheme for diagnostics. It is shown that blood volume fraction and f*d product can be rather surely determined by the reflected green -- red light. One can find f and d separately as well as D by the blue reflectance. The last stage is the derivation of S at about 600 nm.

  17. Platform to investigate aqueous outflow system structure and pressure-dependent motion using high-resolution spectral domain optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Hariri, Sepideh; Johnstone, Murray; Jiang, Yi; Padilla, Steven; Zhou, Zhehai; Reif, Roberto; Wang, Ruikang K.

    2014-10-01

    The aqueous outflow system (AOS) is responsible for maintaining normal intraocular pressure (IOP) in the eye. Structures of the AOS have an active role in regulating IOP in healthy eyes and these structures become abnormal in the eyes with glaucoma. We describe a newly developed system platform to obtain high-resolution images of the AOS structures. By incorporating spectral domain optical coherence tomography (SD-OCT), the platform allows us to systematically control, image, and quantitate the responses of AOS tissue to pressure with a millisecond resolution of pulsed flow. We use SD-OCT to image radial limbal segments from the surface of the trabecular meshwork (TM) with a spatial resolution of ˜5 μm in ex vivo nonhuman primate eyes. We carefully insert a cannula into Schlemm's canal (SC) to control both pressures and flow rates. The experimental results demonstrate the capability of the platform to visualize the unprecedented details of AOS tissue components comparable to that delivered by scanning electron microscopy, as well as to delineate the complex pressure-dependent relationships among the TM, structures within the SC, and collector channel ostia. The described technique provides a new means to characterize the anatomic and pressure-dependent relationships of SC structures, particularly the active motion of collagenous elements at collector channel ostia; such relationships have not previously been amenable to study. Experimental findings suggest that continuing improvements in the OCT imaging of the AOS may provide both insights into the glaucoma enigma and improvements in its management.

  18. Synchrotron Infrared Spectroscopy with Multivariate Spectral Analyses Potentially Facilitates the Classification of Inherent Structures of Feed-Type of Sorghum

    SciTech Connect

    Yu Peiqiang; Damiran, Daalkhaijav; Liu Dasen

    2010-02-03

    The objective of this study was to investigate the inherent structural-chemical features of Chinese feed-type sorghum seed using synchrotron-radiation Fourier transform infrared microspectroscopy (SRFTIRM) with two multivariate molecular spectral analysis techniques: Agglomerative Hierarchical cluster (AHCA) and principal component analyses (PCA). The results show that by application of these two multivariate techniques with the infrared spectroscopy of the SRFTIRM, it makes possible to discriminate and classify the inherent molecular structural features among the different layers of sorghum with a great efficiency. With the SRFTIRM, images of the molecular chemistry of sorghum could be generated at an ultra-spatial resolution. The features of nutrient matrix and nutrient make-up and interactions could be revealed.

  19. Cymantrene radical cation family: spectral and structural characterization of the half-sandwich analogues of ferrocenium ion.

    PubMed

    Laws, Derek R; Chong, Daesung; Nash, Karen; Rheingold, Arnold L; Geiger, William E

    2008-07-30

    The anodic one-electron oxidation of three members of the half-sandwich family of piano-stool compounds MnCp (gamma)(CO) 3, where Cp (gamma) is a generic cyclopentadienyl ligand, has been studied in a CH 2Cl 2/[NBu 4][TFAB] electrolyte (TFAB = [B(C6F5) 4] (-)). The long-sought 17 e (-) radical cation of the parent complex MnCp(CO) 3 (cymantrene, 1, E 1/2 = 0.92 V vs ferrocene) has been shown to be persistent in solutions that use weakly coordinating anions in place of more nucleophilic traditional electrolyte anions. Spectroscopically characterized for the first time, 1 (+) was shown to absorb in the visible (530 nm), near-IR (2066 nm), and IR (2118, 1934 cm (-1)) regions. It was ESR-active at low temperatures (g parallel = 2.213, g perpendicular = 2.079, A parallel (Mn) = 79.2 G, A perpendicular (Mn) = 50 G) and NMR active at room temperature (delta = 22.4 vs TMS). The radical cations of the Cp-functionalized analogues, Mn(eta (5)-C5H 4NH2)(CO) 3, 2, E 1/2 = 0.62 V, and MnCp*(CO) 3 (Cp*= eta (5)-C 5Me 5, 3), E 1/2 = 0.64 V, were generated electrochemically as well by the chemical oxidant [ReCp(CO) 3] (+). The structures of 2 (+) and 3 (+) were determined by X-ray crystallographic studies of their TFAB salts. Compared to the structures of the corresponding neutral compounds, the cations showed elongated Mn-C(O) bonds and shortened C-O bonds, displaying the effect of diminished metal-to-CO backbonding. The bond-length changes in the Mn(CO) 3 moiety were much larger in 3 (+) (avg changes, Mn-C(O) = + 0.142 A, C-O = -0.063 A) than in 2 (+) (avg changes, Mn-C(O) = + 0.006 A, C-O = -0.003 A). Although there were only minor changes in the metal-to-center ring distances upon oxidation of either 2 or 3, there was decidedly less bending of the C(N) atom out of the cyclopentadienyl plane in 2 (+) compared to 2. The optical, vibrational, and magnetic resonance spectra of radicals 2 (+) and 3 (+) were also observed. The spectral data argue for the SOMOs of the 17-electron

  20. Spectral-structural characteristics of the extremely scarce silver arsenic sulfosalts, proustite, smithite, trechmannite and xanthoconite: μ-Raman spectroscopy evidence

    NASA Astrophysics Data System (ADS)

    Kharbish, S.

    2017-04-01

    The spectral - structural features of the rare silver arsenic (Ag-As) sulfosalts, proustite, Ag3AsS3, and the extremely scarce smithite, AgAsS2, trechmannite, AgAsS2 and xanthoconite, Ag3AsS3, were studied by the μ-Raman technique. Stretching - bending vibrations of the pyramidal isolated and interconnected AsS3 groups were responsible for the Raman spectra of the studied sulfosalts. The symmetric and asymmetric stretching modes appear between 380 and 350 cm- 1, whereas those of bending (Ssbnd Assbnd S) vibrations between 335 and 280 cm- 1. The Assbnd S longer bond lengths absolutely demonstrate the red shift (i.e. decrease in energy) from xanthoconite to trechmannite, smithite and proustite and the lowering in FWHM in comparable vibrational modes.

  1. The structural defects and UV-VIS spectral characterization of TiO{sub 2} particles doped in the lattice with Cr{sup 3+} cations

    SciTech Connect

    Liu, Z.L.; Cui, Z.L.; Zhang, Z.K. . E-mail: zhangzk@public.qd.sd.cn

    2005-02-15

    Titania nanoparticles doped with Cr{sup 3+} (2% relative to molar quantity of titania) were prepared and examined by EDS, HRTEM, XRD, and UV-VIS analysis. HRTEM images showed the detailed atomic arrays and vacancy defects of the doped Titania nanocrystals and revealed that the implanted Cr element existed in titania mainly as Cr{sup 3+} ions which located at the lattice positions of Ti{sup 4+} ions. Compared with pure titania, the UV-VIS spectra of the Cr{sup 3+} doped titania show significantly increased absorbance in visible light region. This indicated that the presence of the Cr{sup 3+} ions affected the lattice structure of titania nanocrystals and plays an reformative role in spectral feature of titania.

  2. An Adaptive Spectrally Weighted Structure Tensor Applied to Tensor Anisotropic Nonlinear Diffusion for Hyperspectral Images

    ERIC Educational Resources Information Center

    Marin Quintero, Maider J.

    2013-01-01

    The structure tensor for vector valued images is most often defined as the average of the scalar structure tensors in each band. The problem with this definition is the assumption that all bands provide the same amount of edge information giving them the same weights. As a result non-edge pixels can be reinforced and edges can be weakened…

  3. Exponents of the spectral functions and dynamical structure factor of the 1D Lieb-Liniger Bose gas

    NASA Astrophysics Data System (ADS)

    Carmelo, J. M. P.; Sacramento, P. D.

    2016-06-01

    We study the (k , ω) -plane finite-energy line shape of the zero-temperature one-boson removal spectral function (ω < 0) , one-boson addition spectral function (ω > 0) , and charge dynamical structure factor (ω > 0) of the 1D Lieb-Liniger Bose gas with repulsive boson interaction c > 0. Our analysis of the problem focuses on the line shape at finite excitation energies in the vicinity of these functions spectrum upper (ω < 0) or lower (ω > 0) threshold. Specifically, we derive the exact momentum, interaction, and density dependences of the exponents controlling such a line shape in each of the N = 1 , 2 , 3 , … momentum subdomains k ∈ [(N - 1) 2 πn , N 2 πn ] . Here n = N / L is the boson density, N the boson number, and L the system length. In the thermodynamic limit considered in our study nearly all spectral weight of the dynamical correlation functions is for large values of n / c contained in the N = 1 momentum subdomain k ∈ [ 0 , 2 πn ] . As n / c decreases a small fraction of that weight is transferred to the remaining set of N = 2 , 3 , 4 , … momentum subdomains, particularly to the N = 2 subdomain. In the case of the momentum subdomain k ∈ [ 0 , 2 πn ] , our exact results agree with those of previous studies. For that subdomain the above exponents are plotted as a function of the momentum for several n / c values. Our derivation of the line shapes of the three dynamical correlation functions relies on the use of a simplified form of the pseudofermion dynamical theory of the fermionic 1D Hubbard model suitably modified in this paper for the 1D Bose gas.

  4. [Spectral characteristics of the bioelectrical activity of the cerebral cortex upon electric stimulation of subcortical structures].

    PubMed

    Ianson, Z A; Markin, V P

    1976-01-01

    A spectral-correlation analysis of electrical activity of the rabbit cerebral cortex was made with the use of Dnieper computer, after electrical stimulation (100-250 c/s) of the midbrain reticular formation, the thalamic nonspecific formations (midline nuclei) and different nuclei of the posterior part of the hypothalamic area (ventromedial and posterior hypothalamic nuclei and the lateral field). The background spectrograms were characterized by a high variability; their frequencies ranged from 0,5 to 12 c/s. Under the influence of the electrical stimulation of the indicated formations, a well-pronounced, dominating peak appeared in the spectrograms of the cortical EEG, in the band from 4 to 7 c/s, and the similarity of biopotentials in this rhythm increased. The experimental data show that enhancement of spatial synchronization of the cortical biopotentials under conditions of electrical stimulation of the indicated subcortical formations is based on increased rhythmic oscillations within the theta-band and on a greater coherence in this range.

  5. Spectral Quadrature method for accurate O(N) electronic structure calculations of metals and insulators

    DOE PAGES

    Pratapa, Phanisri P.; Suryanarayana, Phanish; Pask, John E.

    2015-12-02

    We present the Clenshaw–Curtis Spectral Quadrature (SQ) method for real-space O(N) Density Functional Theory (DFT) calculations. In this approach, all quantities of interest are expressed as bilinear forms or sums over bilinear forms, which are then approximated by spatially localized Clenshaw–Curtis quadrature rules. This technique is identically applicable to both insulating and metallic systems, and in conjunction with local reformulation of the electrostatics, enables the O(N) evaluation of the electronic density, energy, and atomic forces. The SQ approach also permits infinite-cell calculations without recourse to Brillouin zone integration or large supercells. We employ a finite difference representation in order tomore » exploit the locality of electronic interactions in real space, enable systematic convergence, and facilitate large-scale parallel implementation. In particular, we derive expressions for the electronic density, total energy, and atomic forces that can be evaluated in O(N) operations. We demonstrate the systematic convergence of energies and forces with respect to quadrature order as well as truncation radius to the exact diagonalization result. In addition, we show convergence with respect to mesh size to established O(N3) planewave results. In conclusion, we establish the efficiency of the proposed approach for high temperature calculations and discuss its particular suitability for large-scale parallel computation.« less

  6. Spectral Quadrature method for accurate O(N) electronic structure calculations of metals and insulators

    NASA Astrophysics Data System (ADS)

    Pratapa, Phanisri P.; Suryanarayana, Phanish; Pask, John E.

    2016-03-01

    We present the Clenshaw-Curtis Spectral Quadrature (SQ) method for real-space O(N) Density Functional Theory (DFT) calculations. In this approach, all quantities of interest are expressed as bilinear forms or sums over bilinear forms, which are then approximated by spatially localized Clenshaw-Curtis quadrature rules. This technique is identically applicable to both insulating and metallic systems, and in conjunction with local reformulation of the electrostatics, enables the O(N) evaluation of the electronic density, energy, and atomic forces. The SQ approach also permits infinite-cell calculations without recourse to Brillouin zone integration or large supercells. We employ a finite difference representation in order to exploit the locality of electronic interactions in real space, enable systematic convergence, and facilitate large-scale parallel implementation. In particular, we derive expressions for the electronic density, total energy, and atomic forces that can be evaluated in O(N) operations. We demonstrate the systematic convergence of energies and forces with respect to quadrature order as well as truncation radius to the exact diagonalization result. In addition, we show convergence with respect to mesh size to established O(N3) planewave results. Finally, we establish the efficiency of the proposed approach for high temperature calculations and discuss its particular suitability for large-scale parallel computation.

  7. Multidimensional spectral load balancing

    SciTech Connect

    Hendrickson, B.; Leland, R.

    1993-01-01

    We describe an algorithm for the static load balancing of scientific computations that generalizes and improves upon spectral bisection. Through a novel use of multiple eigenvectors, our new spectral algorithm can divide a computation into 4 or 8 pieces at once. These multidimensional spectral partitioning algorithms generate balanced partitions that have lower communication overhead and are less expensive to compute than those produced by spectral bisection. In addition, they automatically work to minimize message contention on a hypercube or mesh architecture. These spectral partitions are further improved by a multidimensional generalization of the Kernighan-Lin graph partitioning algorithm. Results on several computational grids are given and compared with other popular methods.

  8. Structural realism versus deployment realism: A comparative evaluation.

    PubMed

    Lyons, Timothy D

    2016-10-01

    In this paper I challenge and adjudicate between the two positions that have come to prominence in the scientific realism debate: deployment realism and structural realism. I discuss a set of cases from the history of celestial mechanics, including some of the most important successes in the history of science. To the surprise of the deployment realist, these are novel predictive successes toward which theoretical constituents that are now seen to be patently false were genuinely deployed. Exploring the implications for structural realism, I show that the need to accommodate these cases forces our notion of "structure" toward a dramatic depletion of logical content, threatening to render it explanatorily vacuous: the better structuralism fares against these historical examples, in terms of retention, the worse it fares in content and explanatory strength. I conclude by considering recent restrictions that serve to make "structure" more specific. I show however that these refinements will not suffice: the better structuralism fares in specificity and explanatory strength, the worse it fares against history. In light of these case studies, both deployment realism and structural realism are significantly threatened by the very historical challenge they were introduced to answer.

  9. Relativistic Calculating the Spectral Lines Hyperfine Structure Parameters for Heavy Ions

    SciTech Connect

    Khetselius, O. Yu.

    2008-10-22

    The energies and constants of the hyperfine structure, derivatives of the one-electron characteristics on nuclear radius, nuclear electric quadrupole, magnetic dipole moments for some Li-like multicharged ions are calculated.

  10. Path integral formalism for the spectral line shape in plasmas: Lyman-{alpha} with fine structure

    SciTech Connect

    Bedida, N.; Meftah, M. T.; Boland, D.; Stamm, R.

    2008-10-22

    We examine in this work the expression of the dipolar autocorrelation function for an emitter in the plasma using the path integrals formalism. The results for Lyman alpha lines with fine structure are retrieved in a compact formula. The expression of the dipolar autocorrelation function takes into account the ions dynamics and the fine structure effects. The electron's effect is represented by the impact operator {phi}{sub e} in the final formula.

  11. Mapping Chemical and Structural Composition of Pharmaceutical and Biological Samples by Raman, Surface-Enhanced Raman and Fluorescence Spectral Imaging

    NASA Astrophysics Data System (ADS)

    Chourpa, Igor; Cohen-Jonathan, Simone; Dubois, Pierre

    Raman spectroscopy is an analytical technique recognised for its structural and conformational specificity. The efficient discrimination of molecular species by Raman is particularly potent for multidimensional microscopic imaging of complex biological environment, as demonstrated in the present book. The commonly admitted problem of Raman, low sensitivity, can often be circumvented due to high output instruments and via approaches like RRS (resonance Raman scattering), SERS (surface-enhanced Raman scattering), TERS (tip-enhanced Raman scattering) or CARS (coherent anti-Stokes Raman scattering). In contrast to the latter, RRS and SERS are realizable with less sophisticated set-up based on common Raman systems. Although more invasive than RRS, SERS provides better sensitivity and quenching of fluorescence. SERRS (surface-enhanced resonance Raman scattering) spectroscopy can be used in coupling with fluorescence and competes in selectivity and sensitivity with spectrofluorimetry. In the chapter below, we use recent applications made in our group to illustrate the use of Raman and SERRS spectral imaging for characterization of biological samples (animal subcutaneous tissue, human cancer cells) and pharmaceutical samples (microparticles for drug delivery, fibres for wound dressing). After a brief description of experimental details on spectral imaging, the chapter will focus on results concerning (i) biocompatible pharmaceutical materials made of alginates and (ii) anticancer drugs in pharmaceutical forms and in biological systems.

  12. Univariate and multivariate molecular spectral analyses of lipid related molecular structural components in relation to nutrient profile in feed and food mixtures

    NASA Astrophysics Data System (ADS)

    Abeysekara, Saman; Damiran, Daalkhaijav; Yu, Peiqiang

    2013-02-01

    The objectives of this study were (i) to determine lipid related molecular structures components (functional groups) in feed combination of cereal grain (barley, Hordeum vulgare) and wheat (Triticum aestivum) based dried distillers grain solubles (wheat DDGSs) from bioethanol processing at five different combination ratios using univariate and multivariate molecular spectral analyses with infrared Fourier transform molecular spectroscopy, and (ii) to correlate lipid-related molecular-functional structure spectral profile to nutrient profiles. The spectral intensity of (i) CH3 asymmetric, CH2 asymmetric, CH3 symmetric and CH2 symmetric groups, (ii) unsaturation (Cdbnd C) group, and (iii) carbonyl ester (Cdbnd O) group were determined. Spectral differences of functional groups were detected by hierarchical cluster analysis (HCA) and principal components analysis (PCA). The results showed that the combination treatments significantly inflicted modifications (P < 0.05) in nutrient profile and lipid related molecular spectral intensity (CH2 asymmetric stretching peak height, CH2 symmetric stretching peak height, ratio of CH2 to CH3 symmetric stretching peak intensity, and carbonyl peak area). Ratio of CH2 to CH3 symmetric stretching peak intensity, and carbonyl peak significantly correlated with nutrient profiles. Both PCA and HCA differentiated lipid-related spectrum. In conclusion, the changes of lipid molecular structure spectral profiles through feed combination could be detected using molecular spectroscopy. These changes were associated with nutrient profiles and functionality.

  13. Comparative study on three highly sensitive absorption measurement techniques characterizing lithium niobate over its entire transparent spectral range.

    PubMed

    Leidinger, M; Fieberg, S; Waasem, N; Kühnemann, F; Buse, K; Breunig, I

    2015-08-24

    We employ three highly sensitive spectrometers: a photoacoustic spectrometer, a photothermal common-path interferometer and a whispering-gallery-resonator-based absorption spectrometer, for a comparative study of measuring the absorption coefficient of nominally transparent undoped, congruently grown lithium niobate for ordinarily and extraordinarily polarized light in the wavelength range from 390 to 3800 nm. The absorption coefficient ranges from below 10(-4) cm(-1) up to 2 cm(-1). Furthermore, we measure the absorption at the Urbach tail as well as the multiphonon edge of the material by a standard grating spectrometer and a Fourier-transform infrared spectrometer, providing for the first time an absorption spectrum of the whole transparency window of lithium niobate. The absorption coefficients obtained by the three highly sensitive and independent methods show good agreement.

  14. Comparative study of novel versus conventional two-wavelength spectrophotometric methods for analysis of spectrally overlapping binary mixture.

    PubMed

    Lotfy, Hayam M; Hegazy, Maha A; Rezk, Mamdouh R; Omran, Yasmin Rostom

    2015-09-05

    Smart spectrophotometric methods have been applied and validated for the simultaneous determination of a binary mixture of chloramphenicol (CPL) and prednisolone acetate (PA) without preliminary separation. Two novel methods have been developed; the first method depends upon advanced absorbance subtraction (AAS), while the other method relies on advanced amplitude modulation (AAM); in addition to the well established dual wavelength (DW), ratio difference (RD) and constant center coupled with spectrum subtraction (CC-SS) methods. Accuracy, precision and linearity ranges of these methods were determined. Moreover, selectivity was assessed by analyzing synthetic mixtures of both drugs. The proposed methods were successfully applied to the assay of drugs in their pharmaceutical formulations. No interference was observed from common additives and the validity of the methods was tested. The obtained results have been statistically compared to that of official spectrophotometric methods to give a conclusion that there is no significant difference between the proposed methods and the official ones with respect to accuracy and precision.

  15. Structure and spectral features of H+(H2O)7: Eigen versus Zundel forms

    NASA Astrophysics Data System (ADS)

    Shin, Ilgyou; Park, Mina; Min, Seung Kyu; Lee, Eun Cheol; Suh, Seung Bum; Kim, Kwang S.

    2006-12-01

    The two dimensional (2D) to three dimensional (3D) transition for the protonated water cluster has been controversial, in particular, for H+(H2O)7. For H+(H2O)7 the 3D structure is predicted to be lower in energy than the 2D structure at most levels of theory without zero-point energy (ZPE) correction. On the other hand, with ZPE correction it is predicted to be either 2D or 3D depending on the calculational levels. Although the ZPE correction favors the 3D structure at the level of coupled cluster theory with singles, doubles, and perturbative triples excitations [CCSD(T)] using the aug-cc-pVDZ basis set, the result based on the anharmonic zero-point vibrational energy correction favors the 2D structure. Therefore, the authors investigated the energies based on the complete basis set limit scheme (which we devised in an unbiased way) at the resolution of the identity approximation Møller-Plesset second order perturbation theory and CCSD(T) levels, and found that the 2D structure has the lowest energy for H+(H2O)7 [though nearly isoenergetic to the 3D structure for D+(D2O)7]. This structure has the Zundel-type configuration, but it shows the quantum probabilistic distribution including some of the Eigen-type configuration. The vibrational spectra of MP2/aug-cc-pVDZ calculations and Car-Parrinello molecular dynamics simulations, taking into account the thermal and dynamic effects, show that the 2D Zundel-type form is in good agreement with experiments.

  16. Importance of cross-correlated relaxation in the spectra of simple organofluorine compounds: Spectral complexity of A3B3X spin systems compared to ABX spin systems

    NASA Astrophysics Data System (ADS)

    Alemany, Lawrence B.; Malloy, Thomas B.; Nunes, Megan M.; Zaibaq, Nicholas G.

    2012-09-01

    In a continuation of our initial investigation of the complex 13C and 19F spectra exhibited by two simple organofluorine compounds, additional organofluorine compounds expected to exhibit a wide range of spectral complexity were studied. Spectral simulations are critical for analyzing the more complex spin systems, in particular, A3B3X and A6B3X. Cross-correlated relaxation is commonly observed; examples of 13Csbnd 19F cross-correlated relaxation are shown with the signals for each nucleus exhibiting unequal relaxation rates. Higher order effects are particularly noticeable in the spectra of perfluoro-t-butyl alcohol because of a large 4JFF value in the (13CF3)(12CF3)212COH isotopomer. The many additional transitions in an A3B3X spin system compared to an ABX spin system result in much more complex 19F (A3 and B3) and 13C (X) spectra, even though only three types of nuclei are involved in each spin system. The corresponding protio compounds typically constitute a much simpler A3M3X spin system because the long-range nJHH coupling (n ⩾ 4) is much smaller than the corresponding long-range nJFF coupling. Spectra previously published for ethane-1-13C (A3B3X) and hexafluoroethane-1-13C (A3M3X) are notable exceptions and are discussed.

  17. Comparing robust and physics-based sea surface temperature retrievals for high resolution, multi-spectral thermal sensors using one or multiple looks

    SciTech Connect

    Borel, C.C.; Clodius, W.B.; Szymanski, J.J.; Theiler, J.P.

    1999-04-04

    With the advent of multi-spectral thermal imagers such as EOS's ASTER high spatial resolution thermal imagery of the Earth's surface will soon be a reality. Previous high resolution sensors such as Landsat 5 had only one spectral channel in the thermal infrared and its utility to determine absolute sea surface temperatures was limited to 6-8 K for water warmer than 25 deg C. This inaccuracy resulted from insufficient knowledge of the atmospheric temperature and water vapor, inaccurate sensor calibration, and cooling effects of thin high cirrus clouds. The authors will present two studies of algorithms and compare their performance. The first algorithm they call robust since it retrieves sea surface temperatures accurately over a fairly wide range of atmospheric conditions using linear combinations of nadir and off-nadir brightness temperatures. The second they call physics-based because it relies on physics-based models of the atmosphere. It attempts to come up with a unique sea surface temperature which fits one set of atmospheric parameters.

  18. Structure, optical properties and thermal stability of Al2O3-WC nanocomposite ceramic spectrally selective solar absorbers

    NASA Astrophysics Data System (ADS)

    Gao, Xiang-Hu; Wang, Cheng-Bing; Guo, Zhi-Ming; Geng, Qing-Fen; Theiss, Wolfgang; Liu, Gang

    2016-08-01

    Traditional metal-dielectric composite coating has found important application in spectrally selective solar absorbers. However, fine metal particles can easily diffuse, congregate, or be oxidized at high temperature, which causes deterioration in the optical properties. In this work, we report a new spectrally selective solar absorber coating, composed of low Al2O3 ceramic volume fraction (Al2O3(L)-WC) layer, high Al2O3 ceramic volume fraction (Al2O3(H)-WC layer) and Al2O3 antireflection layer. The features of our work are: 1) compared with the metal-dielectric composites concept, Al2O3-WC nanocomposite ceramic successfully achieves the all-ceramic concept, which exhibits a high solar absorptance of 0.94 and a low thermal emittance of 0.08, 2) Al2O3 and WC act as filler material and host material, respectively, which are different from traditional concept, 3) Al2O3-WC nanocomposite ceramic solar absorber coating exhibits good thermal stability at 600 °C. In addition, the solar absorber coating is successfully modelled by a commercial optical simulation programme, the result of which agrees with the experimental results.

  19. Comparing two tetraalkylammonium ionic liquids. I. Liquid phase structure

    NASA Astrophysics Data System (ADS)

    Lima, Thamires A.; Paschoal, Vitor H.; Faria, Luiz F. O.; Ribeiro, Mauro C. C.; Giles, Carlos

    2016-06-01

    X-ray scattering experiments at room temperature were performed for the ionic liquids n-butyl-trimethylammonium bis(trifluoromethanesulfonyl)imide, [N1114][NTf2], and methyl-tributylammonium bis(trifluoromethanesulfonyl)imide, [N1444][NTf2]. The peak in the diffraction data characteristic of charge ordering in [N1444][NTf2] is shifted to longer distances in comparison to [N1114][NTf2], but the peak characteristic of short-range correlations is shifted in [N1444][NTf2] to shorter distances. Molecular dynamics (MD) simulations were performed for these ionic liquids using force fields available from the literature, although with new sets of partial charges for [N1114]+ and [N1444]+ proposed in this work. The shifting of charge and adjacency peaks to opposite directions in these ionic liquids was found in the static structure factor, S(k), calculated by MD simulations. Despite differences in cation sizes, the MD simulations unravel that anions are allowed as close to [N1444]+ as to [N1114]+ because anions are located in between the angle formed by the butyl chains. The more asymmetric molecular structure of the [N1114]+ cation implies differences in partial structure factors calculated for atoms belonging to polar or non-polar parts of [N1114][NTf2], whereas polar and non-polar structure factors are essentially the same in [N1444][NTf2]. Results of this work shed light on controversies in the literature on the liquid structure of tetraalkylammonium based ionic liquids.

  20. Comparing two tetraalkylammonium ionic liquids. I. Liquid phase structure.

    PubMed

    Lima, Thamires A; Paschoal, Vitor H; Faria, Luiz F O; Ribeiro, Mauro C C; Giles, Carlos

    2016-06-14

    X-ray scattering experiments at room temperature were performed for the ionic liquids n-butyl-trimethylammonium bis(trifluoromethanesulfonyl)imide, [N1114][NTf2], and methyl-tributylammonium bis(trifluoromethanesulfonyl)imide, [N1444][NTf2]. The peak in the diffraction data characteristic of charge ordering in [N1444][NTf2] is shifted to longer distances in comparison to [N1114][NTf2], but the peak characteristic of short-range correlations is shifted in [N1444][NTf2] to shorter distances. Molecular dynamics (MD) simulations were performed for these ionic liquids using force fields available from the literature, although with new sets of partial charges for [N1114](+) and [N1444](+) proposed in this work. The shifting of charge and adjacency peaks to opposite directions in these ionic liquids was found in the static structure factor, S(k), calculated by MD simulations. Despite differences in cation sizes, the MD simulations unravel that anions are allowed as close to [N1444](+) as to [N1114](+) because anions are located in between the angle formed by the butyl chains. The more asymmetric molecular structure of the [N1114](+) cation implies differences in partial structure factors calculated for atoms belonging to polar or non-polar parts of [N1114][NTf2], whereas polar and non-polar structure factors are essentially the same in [N1444][NTf2]. Results of this work shed light on controversies in the literature on the liquid structure of tetraalkylammonium based ionic liquids.

  1. Comparability of Red/Near-Infrared Reflectance and NDVI Based on the Spectral Response Function between MODIS and 30 Other Satellite Sensors Using Rice Canopy Spectra

    PubMed Central

    Huang, Weijiao; Huang, Jingfeng; Wang, Xiuzhen; Wang, Fumin; Shi, Jingjing

    2013-01-01

    Long-term monitoring of regional and global environment changes often depends on the combined use of multi-source sensor data. The most widely used vegetation index is the normalized difference vegetation index (NDVI), which is a function of the red and near-infrared (NIR) spectral bands. The reflectance and NDVI data sets derived from different satellite sensor systems will not be directly comparable due to different spectral response functions (SRF), which has been recognized as one of the most important sources of uncertainty in the multi-sensor data analysis. This study quantified the influence of SRFs on the red and NIR reflectances and NDVI derived from 31 Earth observation satellite sensors. For this purpose, spectroradiometric measurements were performed for paddy rice grown under varied nitrogen levels and at different growth stages. The rice canopy reflectances were convoluted with the spectral response functions of various satellite instruments to simulate sensor-specific reflectances in the red and NIR channels. NDVI values were then calculated using the simulated red and NIR reflectances. The results showed that as compared to the Terra MODIS, the mean relative percentage difference (RPD) ranged from −12.67% to 36.30% for the red reflectance, −8.52% to −0.23% for the NIR reflectance, and −9.32% to 3.10% for the NDVI. The mean absolute percentage difference (APD) compared to the Terra MODIS ranged from 1.28% to 36.30% for the red reflectance, 0.84% to 8.71% for the NIR reflectance, and 0.59% to 9.32% for the NDVI. The lowest APD between MODIS and the other 30 satellite sensors was observed for Landsat5 TM for the red reflectance, CBERS02B CCD for the NIR reflectance and Landsat4 TM for the NDVI. In addition, the largest APD between MODIS and the other 30 satellite sensors was observed for IKONOS for the red reflectance, AVHRR1 onboard NOAA8 for the NIR reflectance and IKONOS for the NDVI. The results also indicated that AVHRRs onboard NOAA7

  2. Comparability of red/near-infrared reflectance and NDVI based on the spectral response function between MODIS and 30 other satellite sensors using rice canopy spectra.

    PubMed

    Huang, Weijiao; Huang, Jingfeng; Wang, Xiuzhen; Wang, Fumin; Shi, Jingjing

    2013-11-26

    Long-term monitoring of regional and global environment changes often depends on the combined use of multi-source sensor data. The most widely used vegetation index is the normalized difference vegetation index (NDVI), which is a function of the red and near-infrared (NIR) spectral bands. The reflectance and NDVI data sets derived from different satellite sensor systems will not be directly comparable due to different spectral response functions (SRF), which has been recognized as one of the most important sources of uncertainty in the multi-sensor data analysis. This study quantified the influence of SRFs on the red and NIR reflectances and NDVI derived from 31 Earth observation satellite sensors. For this purpose, spectroradiometric measurements were performed for paddy rice grown under varied nitrogen levels and at different growth stages. The rice canopy reflectances were convoluted with the spectral response functions of various satellite instruments to simulate sensor-specific reflectances in the red and NIR channels. NDVI values were then calculated using the simulated red and NIR reflectances. The results showed that as compared to the Terra MODIS, the mean relative percentage difference (RPD) ranged from -12.67% to 36.30% for the red reflectance, -8.52% to -0.23% for the NIR reflectance, and -9.32% to 3.10% for the NDVI. The mean absolute percentage difference (APD) compared to the Terra MODIS ranged from 1.28% to 36.30% for the red reflectance, 0.84% to 8.71% for the NIR reflectance, and 0.59% to 9.32% for the NDVI. The lowest APD between MODIS and the other 30 satellite sensors was observed for Landsat5 TM for the red reflectance, CBERS02B CCD for the NIR reflectance and Landsat4 TM for the NDVI. In addition, the largest APD between MODIS and the other 30 satellite sensors was observed for IKONOS for the red reflectance, AVHRR1 onboard NOAA8 for the NIR reflectance and IKONOS for the NDVI. The results also indicated that AVHRRs onboard NOAA7-17 showed

  3. Applications of Structural Mass Spectrometry to Metabolomics: Clarifying Bond Specific Spectral Signatures with Isotope Edited Spectroscopy

    NASA Astrophysics Data System (ADS)

    Gorlova, Olga; Wolke, Conrad T.; Fournier, Joseph; Colvin, Sean; Johnson, Mark; Miller, Scott

    2015-06-01

    Comprehensive FTIR, MS/MS and NMR of pharmaceuticals are generally readily available but characterization of their metabolites has been an obstacle. Atorvastatin is a statin drug responsible for the maintenance of cholesterol in the body. Diovan is an angiostensin receptor antagonist used to treat high blood pressure and congestive heart failure. The field of metabolomics, however, is struggling to obtain the identity of their structures. We implement mass spectrometry with cryogenic ion spectroscopy to study gaseous ions of the desired metabolites which, in combination, not only identify the mass of the metabolite but also elucidate their structures through isotope-specific infrared spectroscopy.

  4. How do disordered regions achieve comparable functions to structured domains?

    PubMed

    Latysheva, Natasha S; Flock, Tilman; Weatheritt, Robert J; Chavali, Sreenivas; Babu, M Madan

    2015-06-01

    The traditional structure to function paradigm conceives of a protein's function as emerging from its structure. In recent years, it has been established that unstructured, intrinsically disordered regions (IDRs) in proteins are equally crucial elements for protein function, regulation and homeostasis. In this review, we provide a brief overview of how IDRs can perform similar functions to structured proteins, focusing especially on the formation of protein complexes and assemblies and the mediation of regulated conformational changes. In addition to highlighting instances of such functional equivalence, we explain how differences in the biological and physicochemical properties of IDRs allow them to expand the functional and regulatory repertoire of proteins. We also discuss studies that provide insights into how mutations within functional regions of IDRs can lead to human diseases.

  5. Determining protein similarity by comparing hydrophobic core structure.

    PubMed

    Gadzała, M; Kalinowska, B; Banach, M; Konieczny, L; Roterman, I

    2017-02-01

    Formal assessment of structural similarity is - next to protein structure prediction - arguably the most important unsolved problem in proteomics. In this paper we propose a similarity criterion based on commonalities between the proteins' hydrophobic cores. The hydrophobic core emerges as a result of conformational changes through which each residue reaches its intended position in the protein body. A quantitative criterion based on this phenomenon has been proposed in the framework of the CASP challenge. The structure of the hydrophobic core - including the placement and scope of any deviations from the idealized model - may indirectly point to areas of importance from the point of view of the protein's biological function. Our analysis focuses on an arbitrarily selected target from the CASP11 challenge. The proposed measure, while compliant with CASP criteria (70-80% correlation), involves certain adjustments which acknowledge the presence of factors other than simple spatial arrangement of solids.

  6. Supramolecular structure and spectral studies on mixed-ligand complexes derived from β-diketone with azodye rhodanine derivatives.

    PubMed

    El-Sonbati, A Z; Diab, M A; Belal, A A M; Morgan, Sh M

    2012-12-01

    A novel method to synthesize some mononuclear ternary palladium(II) complexes of the general formula [Pd(L(n))L] (where LH=diketone=acetylacetone, HL(n)=azorhodanine) has been synthesize. The structure of the new mononuclear ternary palladium(II) complexes was characterized using elemental analysis, spectral (electronic, infrared and (1)H &(13)C NMR) studies, magnetic susceptibility measurements and thermal studies. The IR showed that the ligands (HL(n) & LH) act as monobasic bidentate through the azodye nitrogen, oxygen keto moiety and two enolato oxygen atoms. The molar conductivities show that all the complexes are non-electrolytes. Bidentate chelating nature of β-diketone and azorhodanine anions in the complexes was characterized by (electronic, infrared and (1)H &(13)C NMR) spectra. Square planar geometry around palladium has been assigned in all complexes. Various ligand and nephelouxetic parameter have been calculated for the complexes. The thermal decomposition for complexes was studied.

  7. Supramolecular structure and spectral studies on mixed-ligand complexes derived from β-diketone with azodye rhodanine derivatives

    NASA Astrophysics Data System (ADS)

    El-Sonbati, A. Z.; Diab, M. A.; Belal, A. A. M.; Morgan, Sh. M.

    2012-12-01

    A novel method to synthesize some mononuclear ternary palladium(II) complexes of the general formula [Pd(Ln)L] (where LH = diketone = acetylacetone, HLn = azorhodanine) has been synthesize. The structure of the new mononuclear ternary palladium(II) complexes was characterized using elemental analysis, spectral (electronic, infrared and 1H &13C NMR) studies, magnetic susceptibility measurements and thermal studies. The IR showed that the ligands (HLn & LH) act as monobasic bidentate through the azodye nitrogen, oxygen keto moiety and two enolato oxygen atoms. The molar conductivities show that all the complexes are non-electrolytes. Bidentate chelating nature of β-diketone and azorhodanine anions in the complexes was characterized by (electronic, infrared and 1H &13C NMR) spectra. Square planar geometry around palladium has been assigned in all complexes. Various ligand and nephelouxetic parameter have been calculated for the complexes. The thermal decomposition for complexes was studied.

  8. Crystal growth, spectral, structural and optical studies of π-conjugated stilbazolium crystal: 4-bromobenzaldehyde-4'-N'-methylstilbazolium tosylate.

    PubMed

    Krishna Kumar, M; Sudhahar, S; Bhagavannarayana, G; Mohan Kumar, R

    2014-05-05

    Nonlinear optical (NLO) organic compound, 4-bromobenzaldehyde-4'-N'-methylstilbazolium tosylate was synthesized by reflux method. The formation of molecular complex was confirmed from (1)H NMR, FT-IR and FT-Raman spectral analyses. The single crystals were grown by slow evaporation solution growth method and the crystal structure and atomic packing of grown crystal was identified. The morphology and growth axis of grown crystal were determined. The crystal perfection was analyzed using high resolution X-ray diffraction study on (001) plane. Thermal stability, decomposition stages and melting point of the grown crystal were analyzed. The optical absorption coefficient (α) and energy band gap (E(g)) of the crystal were determined using UV-visible absorption studies. Second harmonic generation efficiency of the grown crystal was examined by Kurtz powder method with different particle size using 1064 nm laser. Laser induced damage threshold study was carried out for the grown crystal using Nd:YAG laser.

  9. Comparative Analysis on Time Series with Included Structural Break

    NASA Astrophysics Data System (ADS)

    Andreeski, Cvetko J.; Vasant, Pandian

    2009-08-01

    The time series analysis (ARIMA models) is a good approach for identification of time series. But, if we have structural break in the time series, we cannot create only one model of time series. Further more, if we don't have enough data between two structural breaks, it's impossible to create valid time series models for identification of the time series. This paper explores the possibility of identification of the inflation process dynamics via of the system-theoretic, by means of both Box-Jenkins ARIMA methodologies and artificial neural networks.

  10. A Mass Spectral Chlorine Rule for Use in Structure Determinations in Sophomore Organic Chemistry

    ERIC Educational Resources Information Center

    Gross, Ray A., Jr.

    2004-01-01

    The low-resolution mass spectrum of integral masses is used to determine the number of bromine and chlorine atoms in an organic compound. The chlorine rule is a tool suitable for use in structural determinations in first year organic chemistry and it is supported by the ability of sophomore-level students to successfully determine n and m from the…

  11. Spectral characteristics of heterocyclic compounds with a chain structure, cooled in an ultrasonic jet

    NASA Astrophysics Data System (ADS)

    Povedailo, V. A.; Yakovlev, D. L.

    2006-11-01

    We have recorded the fluorescence excitation spectra of three heterocyclic compounds with a chain structure [BPO (2-phenyl-5-(4-diphenylyl)oxazole), POPOP (1,4-di[2-(5-phenyloxazolyl)]benzene, and TOPOT (1,4-di[2-(5-n-tolyloxazolyl)]benzene] and the fluorescence spectra of POPOP, under conditions where the molecules were cooled in an ultrasonic helium jet. A line structure is observed in the spectra of POPOP and TOPOT; for the BPO molecules, whose configuration changes considerably during electronic excitation, vibrational structure is apparent only in the low-frequency region of the excitation spectrum, and a diffuse spectrum is recorded starting from ν 0 0 + 200 cm-1. For all the compounds, in the spectra we recorded vibrations with frequencies up to 100 cm-1, arising due to the flexibility of the molecular structure. The rotational contours of the lines for the electronic and vibronic transitions of the POPOP molecules (Trot = 10.5 K) and TOPOT molecules (Trot = 15 K) are structureless and bell-shaped. The degree of polarization of the fluorescence Pfl for the jet-cooled POPOP molecules for excitation of vibrations along the absorption band up to 2000 cm-1 above ν 0 0 is practically constant (˜8.4%) and matches Pfl for high-temperature vapors.

  12. Spectral and structural features of Lu1 - x RE x BO3 compounds

    NASA Astrophysics Data System (ADS)

    Shmurak, S. Z.; Kedrov, V. V.; Kiselev, A. P.; Fursova, T. N.; Shmyt'ko, I. M.

    2015-08-01

    The luminescence spectra, luminescence excitation spectra, IR absorption spectra, and crystal structure of orthoborates Lu1 - x RE x BO3 ( RE = Eu, Gd, Tb, Y, Dy) have been investigated. It has been found that the solid solution consisting of a LuBO3 orthoborate, which has two stable structural modifications (calcite and vaterite), and an REBO3 orthoborate, which has one structural modification (vaterite), crystallizes only in the vaterite structure when the concentration of a rare-earth ion substituting for lutetium exceeds 15-20 at %. The investigation of the photoluminescence spectra has demonstrated that, for rare-earth ions Lu3+, Eu3+, Y3+, and Gd3+ in the vaterite modification of Lu1 - x RE x BO3 orthoborates, there are at least two positions that are not equivalent in the symmetry of the local environment. It has been established that the maximum intensity of the luminescence of the vaterite modification of Lu1 - x Tb x BO3 compounds synthesized at 970°C, which is observed at a terbium concentration of 15 at %, is several times higher than the maximum intensity of the luminescence of the calcite modification.

  13. Mixed-grass prairie canopy structure and spectral reflectance vary with topographic position

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Managers of the nearly 0.5 million ha of public lands in North and South Dakota rely heavily on manual measurements of canopy height in autumn to ensure conservation of grassland structure for wildlife and forage for livestock. However, more comprehensive assessment tools could be developed for the...

  14. Extracting structural information from the OH and CH stretch spectral regions with a local mode approach

    NASA Astrophysics Data System (ADS)

    Tabor, Daniel P.

    This thesis focuses on the development and application of a reduced-dimensional local mode approach to the calculation of the infrared spectra of molecules and clusters. The basic properties of infrared spectra can often be understood in the context of the harmonic oscillator/linear dipole approximation. However, the spectra of the molecules and clusters of interest in this study contain additional complications due to stretch-bend Fermi resonances. The presence of these resonances makes the assignment of vibrational spectra to particular isomers or conformers much more difficult. By using a reduced-dimensional local mode approach, we are able to incorporate the important anharmonic terms in an efficient manner and accurately model the spectra with only modest additional costs. The first part of this thesis is a detailed study on the CH stretch region vibrational spectroscopy of a series of molecules with alkyl and alkoxy groups. The conclusions of this study formed the foundation for the construction of the model for the rest of the molecules in this thesis. The approach is shown to model all of the major features of short alkylbenzenes. The second part investigates the interaction of a benzene molecule with a cluster of water molecules in the gas phase. An understanding of these structures provides a framework for understanding the solvation structure of benzene in water. Using the model Hamiltonian, we are able to make definitive assignments of the structures of benzene complexed with both six and seven water molecules based on their infrared spectra in the OH stretch region. For both clusters, the assigned structures show a fundamental change in the structure of the water network, illustrating the strong impact that a benzene molecule can have on the structure of water. Finally, we employ the model to investigate the structure and spectroscopy of longer alkylbenzene chains, alkylbenzyl radicals, and water clusters solvated with other molecules. This series of

  15. Comparative Effectiveness of Contextual and Structural Method of Teaching Vocabulary

    ERIC Educational Resources Information Center

    Behlol, Malik; Kaini, Mohammad Munir

    2011-01-01

    The study was conducted to find out effectiveness of contextual an, structural method of teaching vocabulary in English at secondary level. It was an experimental study in which the pretest posttest design was used. The population of the study was the students of secondary classes studying in Government secondary schools of Rawalpindi District.…

  16. Structural and Social Psychological Correlates of Prisonization: A Comparative Analysis.

    ERIC Educational Resources Information Center

    Thomas, Charles W.; And Others

    This study considers some aspects of "prisonization," or the process by which inmates adapt to confinement. Specifically, it further examines two ideas suggested by earlier studies. One is the belief that the structural characteristics of many prisons promote rather than inhibit assimilation into an inmate normative system that is opposed to the…

  17. Comparative structural biology of eubacterial and archaeal oligosaccharyltransferases.

    PubMed

    Maita, Nobuo; Nyirenda, James; Igura, Mayumi; Kamishikiryo, Jun; Kohda, Daisuke

    2010-02-12

    Oligosaccharyltransferase (OST) catalyzes the transfer of an oligosaccharide from a lipid donor to an asparagine residue in nascent polypeptide chains. In the bacterium Campylobacter jejuni, a single-subunit membrane protein, PglB, catalyzes N-glycosylation. We report the 2.8 A resolution crystal structure of the C-terminal globular domain of PglB and its comparison with the previously determined structure from the archaeon Pyrococcus AglB. The two distantly related oligosaccharyltransferases share unexpected structural similarity beyond that expected from the sequence comparison. The common architecture of the putative catalytic sites revealed a new catalytic motif in PglB. Site-directed mutagenesis analyses confirmed the contribution of this motif to the catalytic function. Bacterial PglB and archaeal AglB constitute a protein family of the catalytic subunit of OST along with STT3 from eukaryotes. A structure-aided multiple sequence alignment of the STT3/PglB/AglB protein family revealed three types of OST catalytic centers. This novel classification will provide a useful framework for understanding the enzymatic properties of the OST enzymes from Eukarya, Archaea, and Bacteria.

  18. Comparative static curing versus dynamic curing on tablet coating structures.

    PubMed

    Gendre, Claire; Genty, Muriel; Fayard, Barbara; Tfayli, Ali; Boiret, Mathieu; Lecoq, Olivier; Baron, Michel; Chaminade, Pierre; Péan, Jean Manuel

    2013-09-10

    Curing is generally required to stabilize film coating from aqueous polymer dispersion. This post-coating drying step is traditionally carried out in static conditions, requiring the transfer of solid dosage forms to an oven. But, curing operation performed directly inside the coating equipment stands for an attractive industrial application. Recently, the use of various advanced physico-chemical characterization techniques i.e., X-ray micro-computed tomography, vibrational spectroscopies (near infrared and Raman) and X-ray microdiffraction, allowed new insights into the film-coating structures of dynamically cured tablets. Dynamic curing end-point was efficiently determined after 4h. The aim of the present work was to elucidate the influence of curing conditions on film-coating structures. Results demonstrated that 24h of static curing and 4h of dynamic curing, both performed at 60°C and ambient relative humidity, led to similar coating layers in terms of drug release properties, porosity, water content, structural rearrangement of polymer chains and crystalline distribution. Furthermore, X-ray microdiffraction measurements pointed out different crystalline coating compositions depending on sample storage time. An aging mechanism might have occur during storage, resulting in the crystallization and the upward migration of cetyl alcohol, coupled to the downward migration of crystalline sodium lauryl sulfate within the coating layer. Interestingly, this new study clearly provided further knowledge into film-coating structures after a curing step and confirmed that curing operation could be performed in dynamic conditions.

  19. Synthesis, spectral, structural and DFT studies of novel dialkylfluorene decorated phenothiazine-3-carbaldehyde

    NASA Astrophysics Data System (ADS)

    Karuppasamy, Ayyanar; Udhaya kumar, Chandran; Velayutham Pillai, Muthiah Pillai; Ramalingan, Chennan

    2017-04-01

    A novel conjugated alkylfluorene decorated phenothiazine carbaldehyde, 10-(9,9-diethyl-9H-fluoren-2-yl)-10H-phenothiazine-3-carbaldehyde (FPTZC) was synthesized and fully characterized by spectroscopic, elemental and single crystal XRD analyses. The geometry and electronic structures were arrived using B3LYP/6-31G++(d,p) calculations. The geometrical parameters, resulted from single crystal XRD, are in accord with the computed ones. FT-IR and NMR spectra of the title molecule have been investigated computationally. The theoretical NMR results are found to be similar with the experimental ones. The calculated vibrational frequencies of normal modes were matched well with the experimental values. These studies provide insights into their molecular geometry and electronic structures.

  20. Realization of spectral tunable filter based on thermal effect in microfiber structure

    NASA Astrophysics Data System (ADS)

    Nodehi, S.; Mohammed, W. S.; Ahmad, H.; Harun, S. W.

    2016-03-01

    This paper demonstrates a new approach for tuning the extinction ratio of a complex microfiber structure output using thermal effect. The microfiber filter device comprises of a microfiber Mach-Zehnder interferometer followed a knot structure, where temperature is controlled by a DC current applied to a copper wire placed inside the knot. This enables electrical tuning, where applying electrical current increases the temperature and affects the optical path. The change of temperature facilitates the fine tuning of the resonance output spectrum. From the experiment, it was observed that the extinction ratio of the output comb spectrum can be controlled within 2 dB to 10 dB by varying the current rating from 0 A to 1.22 A.

  1. Spectral scalability and optical spectra of fractal multilayer structures: FDTD analysis

    NASA Astrophysics Data System (ADS)

    Simsek, Sevket; Palaz, Selami; Mamedov, Amirullah M.; Ozbay, Ekmel

    2017-01-01

    An investigation of the optical properties and band structures for the conventional and Fibonacci photonic crystals (PCs) based on SrTiO3 and Sb2Te3 is made in the present research. Here, we use one-dimensional SrTiO3- and Sb2Te3-based layers. We have theoretically calculated the photonic band structure and transmission spectra of SrTiO3- and Sb2Te3-based PC superlattices. The position of minima in the transmission spectrum correlates with the gaps obtained in the calculation. The intensity of the transmission depths is more intense in the case of higher refractive index contrast between the layers.

  2. Spectral Factorization and Homogenization Methods for Modeling and Control of Flexible Structures.

    DTIC Science & Technology

    1986-12-15

    Summary .. .. .. .. .. ... ... ... ... ... .... ... .. 44 4.3 Homogenization and Stabilizing Control of Lattice Structures .. .. .. .... 44 4.4...heavily dependent on. the type of damping Pr models used. If one is willing to assume a sufficient amount of viscous damping then stabilizing control can...correctors _4% and the data of the problem. 4.3 Homogenization and Stabilizing Control of Lattice Struc- tures 4 In this subsection we show that the

  3. Structure elucidation and complete NMR spectral assignments of four new diterpenoids from Smallantus sonchifolius.

    PubMed

    Dou, De-Qiang; Tian, Fang; Qiu, Ying-Kun; Kang, Ting-Guo; Dong, Feng

    2008-08-01

    Four new diterpenoids, named smaditerpenic acid A-D, together with five known compounds, were isolated from the H(2)O extract of the leaves of Smallantus sonchifolius (yacon) cultivated in Liaoning, China and their structures were elucidated on the basis of one- and two-dimensional NMR (including (1)H, (13)C-NMR, (1)H-(1)H COSY, HSQC, TOCSY, HMBC, and ROESY), electrospray ionization mass spectrometry (ESI-MS), and chemical methods.

  4. Spectrally encoded fiber-based structured lighting probe for intraoperative 3D imaging

    PubMed Central

    Clancy, Neil T.; Stoyanov, Danail; Maier-Hein, Lena; Groch, Anja; Yang, Guang-Zhong; Elson, Daniel S.

    2011-01-01

    Three dimensional quantification of organ shape and structure during minimally invasive surgery (MIS) could enhance precision by allowing the registration of multi-modal or pre-operative image data (US/MRI/CT) with the live optical image. Structured illumination is one technique to obtain 3D information through the projection of a known pattern onto the tissue, although currently these systems tend to be used only for macroscopic imaging or open procedures rather than in endoscopy. To account for occlusions, where a projected feature may be hidden from view and/or confused with a neighboring point, a flexible multispectral structured illumination probe has been developed that labels each projected point with a specific wavelength using a supercontinuum laser. When imaged by a standard endoscope camera they can then be segmented using their RGB values, and their 3D coordinates calculated after camera calibration. The probe itself is sufficiently small (1.7 mm diameter) to allow it to be used in the biopsy channel of commonly used medical endoscopes. Surgical robots could therefore also employ this technology to solve navigation and visualization problems in MIS, and help to develop advanced surgical procedures such as natural orifice translumenal endoscopic surgery. PMID:22076272

  5. Alteration of citrine structure by hydrostatic pressure explains the accompanying spectral shift

    PubMed Central

    Barstow, Buz; Ando, Nozomi; Kim, Chae Un; Gruner, Sol M.

    2008-01-01

    A protein molecule is an intricate system whose function is highly sensitive to small external perturbations. However, no examples that correlate protein function with progressive subangstrom structural perturbations have thus far been presented. To elucidate this relationship, we have investigated a fluorescent protein, citrine, as a model system under high-pressure perturbation. The protein has been compressed to produce deformations of its chromophore by applying a high-pressure cryocooling technique. A closely spaced series of x-ray crystallographic structures reveals that the chromophore undergoes a progressive deformation of up to 0.8 Å at an applied pressure of 500 MPa. It is experimentally demonstrated that the structural motion is directly correlated with the progressive fluorescence shift of citrine from yellow to green under these conditions. This protein is therefore highly sensitive to subangstrom deformations and its function must be understood at the subangstrom level. These results have significant implications for protein function prediction and biomolecule design and engineering, because they suggest methods to tune protein function by modification of the protein scaffold. PMID:18768811

  6. [Analysis of cloud spectral structure characteristics based on cloud profile radar data].

    PubMed

    Han, Yong; Lü, Da-Ren

    2013-04-01

    Cloud plays a very important role in the earth-atmosphere system. However, the current climate models are still lacking data about internal fine structure of cloud. And when the traditional passive satellite radiometer is used for remote sense, a plentiful information of the vertical distribution of cloud layer will be lost. For these reasons, NASA proposed the launch project of CloudSat, Whose purpose is to provide the necessary observation, and then allow us to understand better the internal structure of the cloud. CloudSat was successfully launched on April 28, 2006. It carried the first cloud profile radar (CPR) with W band (94 GHz), which can provide continuous and global time sequence vertical structure and characteristics of cloud. In the present paper, using CloudSat satellite data, we analyzed the 8th "Morakot" and 15th " Koppu" typhoon cloud systems. According to the "typhoon" cloud detection results, the radar reflectivity, cloud types and optical thickness successive variation of cloud layer were gotten, which will provide a reference for studying optical properties of typhoon cloud system.

  7. Higher order moments, structure functions and spectral ratios in near- and far-wakes of a wind turbine array

    NASA Astrophysics Data System (ADS)

    Ali, Naseem; Aseyev, A.; McCraney, J.; Vuppuluri, V.; Abbass, O.; Al Jubaree, T.; Melius, M.; Cal, R. B.

    2014-11-01

    Hot-wire measurements obtained in a 3 × 3 wind turbine array boundary layer are utilized to analyze higher order statistics which include skewness, kurtosis as well as the ratios of structure functions and spectra. The ratios consist of wall-normal to streamwise components for both quantities. The aim is to understand the degree of anisotropy in the flow for the near- and far-wakes of the flow field where profiles at one diameter and five diameters are considered, respectively. The skewness at top tip for both wakes show a negative skewness while below the turbine canopy, this terms are positive. The kurtosis shows a Gaussian behavior in the near-wake immediately at hub-height. In addition, the effect due to the passage of the rotor in tandem with the shear layer at the top tip renders relatively high differences in the fourth order moment. The second order structure function and spectral ratios are found to exhibit anisotropic behavior at the top and bottom-tips for the large scales. Mixed structure functions and co-spectra are also considered in the context of isotropy.

  8. Synthesis, spectral characterization, molecular structure and pharmacological studies of N'-(1, 4-naphtho-quinone-2yl) isonicotinohyWdrazide

    NASA Astrophysics Data System (ADS)

    Kavitha Rani, P. R.; Fernandez, Annette; George, Annie; Remadevi, V. K.; Sudarsanakumar, M. R.; Laila, Shiny P.; Arif, Muhammed

    2015-01-01

    A simple and efficient procedure was employed for the synthesis of N'-(1,4-naphtho-quinone-2-yl) isonicotinohydrazide (NIH) by the reaction of 2-hydroxy-1,4-naphthaquinone (lawsone) and isonicotinoyl hydrazine in methanol using ultrasonic irradiation. Lawsone is the principal dye, isolated from the leaves of henna (Lawsonia inermis). Structural modification was done on the molecule aiming to get a more active derivative. The structure of the parent compound and the derivative was characterized by elemental analyses, infrared, electronic, 1H, 13C NMR and GC-MS spectra. The fluorescence spectral investigation of the compound was studied in DMSO and ethanol. Single crystal X-ray diffraction studies reveal that NIH crystallizes in monoclinic space group. The DNA cleavage study was monitored by gel electrophoresis method. The synthesized compound was found to have significant antioxidant activity against DPPH radical (IC50 = 58 μM). The in vitro cytotoxic studies of the derivative against two human cancer cell lines MCF-7 (human breast cancer) and HCT-15 (human colon carcinoma cells) using MTT assay revealed that the compound exhibited higher cytotoxic activity with a lower IC50 value indicating its efficiency in killing the cancer cells even at low concentrations. These results suggest that the structural modifications performed on lawsone could be considered a good strategy to obtain a more active drug.

  9. Large tree species richness is associated with topography, forest structure and spectral heterogeneity in a neotropical rainforest

    NASA Astrophysics Data System (ADS)

    Fricker, G. A.; Wolf, J. A.; Gillespie, T.; Meyer, V.; Hubbell, S. P.; Santo, F. E.; Saatchi, S. S.

    2013-12-01

    Large tropical canopy trees contain the majority of forest biomass in addition to being the primary producers in the forest ecosystem in terms of both food and structural habitat. The spatial distributions of large tropical trees are non-randomly distributed across environmental gradients in light, water and nutrients. These environmental gradients are a result of the biophysical processes related to topography and three-dimensional forest structure. In this study we examine large (>10 cm) diameter tree species richness across Barro Colorado Nature Monument in a tropical moist forest in Panama using active and passive remote sensing. Airborne light detection and ranging and high-resolution satellite imagery were used to quantify spectral heterogeneity, sub-canopy topography and vertical canopy structure across existing vegetation plots to model the extent to which remote sensing variables can be used to explain variation in large tree species richness. Plant species richness data was calculated from the stem mapped 50-ha forest dynamics plot on Barro Colorado Island in addition to 8 large tree plots across the Barro Colorado Nature Monument at 1.0 ha and 0.25 ha spatial scales. We investigated four statistical models to predict large tree species richness including spectral, topographic, vertical canopy structure and a combined ';global' model which includes all remote sensing derived variables. The models demonstrate that remote sensing derived variables can capture a significant fraction (R2= 0.54 and 0.36) of observed variation in tree species richness across the 1.0 and 0.25 ha spatial scales respectively. A selection of remote sensing derived predictor variables. A) World View-2 satellite imagery in RGB/true color. B) False color image of the principal component analysis. C) Normalized Difference Vegetation Index (NDVI). D) Simple Ratio Index. E) Quickbird satellite imagery in RGB/true color. F) False color image of the principal component analysis. G) NDVI. H

  10. Synthesis, crystal structures and spectral characterization of chiral 4-R-1,2,4-triazoles

    NASA Astrophysics Data System (ADS)

    Gural'skiy, Il'ya A.; Reshetnikov, Viktor A.; Omelchenko, Irina V.; Szebesczyk, Agnieszka; Gumienna-Kontecka, Elzbieta; Fritsky, Igor O.

    2017-01-01

    1,2,4-triazoles attract attention as actively used medications and ligands for constructing coordination architectures. In this paper we describe four optically active 4-substituted 1,2,4-triazoles that have been prepared by Bayer's synthesis from the corresponding aliphatic chiral amines. This approach tends to be universal towards different triazoles and permits to conserve a homochirality of substrates. Novel asymmetric molecules have been characterized by spectroscopic techniques and their structures have been retrieved from the single crystal X-ray analysis. Chiro-optical studies of these heterocycles have been made by means of circular dichroism spectroscopy.

  11. Self-similar spectral structures and edge-locking hierarchy in open-boundary spin chains

    SciTech Connect

    Haque, Masudul

    2010-07-15

    For an anisotropic Heisenberg (XXZ) spin chain, we show that an open boundary induces a series of approximately self-similar features at different energy scales, high up in the eigenvalue spectrum. We present a nonequilibrium phenomenon related to this fractal structure, involving states in which a connected block near the edge is polarized oppositely to the rest of the chain. We show that such oppositely polarized blocks can be 'locked' to the edge of the spin chain and that there is a hierarchy of edge-locking effects at various orders of the anisotropy. The phenomenon enables dramatic control of quantum-state transmission and magnetization control.

  12. Fine structure of transient waves in a random medium: The correlation and spectral density functions

    NASA Technical Reports Server (NTRS)

    Wenzel, Alan R.

    1994-01-01

    This is essentially a progress report on a theoretical investigation of the propagation of transient waves in a random medium. The emphasis in this study is on applications to sonic-boom propagation, particularly as regards the effect of atmospheric turbulence on the sonic-boom waveform. The analysis is general, however, and is applicable to other types of waves besides sonic-boom waves. The phenomenon of primary concern in this investigation is the fine structure of the wave. A figure is used to illustrate what is meant by finestructure.

  13. A multizone model for composite disk-corona structure and spectral formation in active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Shimura, Toshiya; Mineshige, Shin; Takahara, Fumio

    1995-01-01

    We study a composite disk-corona structure in active galactic nuclei (AGN) by solving for radiative transfer, hydrostatic balance, and energy balance at each layer with a different vertical height. A key assumption is that a fraction f of total energy is dissipated in a corona with a Thomson optical depth of tauC, and a remaining fraction, 1-f, within a main body of the disk. As f increases, a two-phased structure grows with an abrupt temperature jump at the interface. As a result, the emergent spectrum varies from a blackbody-like spectrum to a power-law spectrum with a high-energy cutoff. The power-law index is insensitive to a mass of a central black hole, accretion rate, and tauC, and decreases with an increase of f, reaching approximately 0.9 for f approximately = 1. The cutoff energy (Ecutoff) is, on the other hand, related to tauC as tauC Ecutoff approximately = 90 keV. The radiative field is a blackbody at the midplane of the disk, but has a power-law energy distribution near the surface due to a reflection of high-energy photons emanating from the corona. The resultant spectra thus produce litle UV bumps. To account for the observed AGN spectra, therefore, we should consider more complicated situations such as a partial coverage of hot corona and an effect of absorption by heavy elements.

  14. Structural, electronic, and spectral properties of six ZnO bulk polymorphs

    NASA Astrophysics Data System (ADS)

    Sponza, Lorenzo; Goniakowski, Jacek; Noguera, Claudine

    2015-02-01

    Relying on HSE03, G0W0 , and random phase approximation +G0W0 approaches, this study provides a complete characterization of the electronic properties of six ZnO bulk polymorphs, including quasiparticle spectra, absorption, and electron energy-loss spectra. It focuses on the series zinc blende, wurtzite, body-centered tetragonal, sodalite, and cubane structures, along which atoms have similar local tetrahedral environments and decreasing atomic density, to which the hexagonal boron nitride structure was added. All trends in the electronic properties—gap opening, blueshift of low-energy interband transitions, redshift of the main absorption peak, the frequency at which the real part of the dielectric tensor vanishes, and the plasmon energy—were interpreted in terms of the two main effects resulting from the decrease of the atomic density along the series: a bandwidth narrowing close to the gap edge and a decrease (in absolute value) of the electrostatic potential acting on the zinc and oxygen ions. This work gives firm grounds to help and foster spectroscopic experiments on ZnO polymorphs. It represents a preliminary step towards the study of thin-film properties.

  15. Iron modified structural and optical spectral properties of bismuth silicate glasses

    NASA Astrophysics Data System (ADS)

    Parmar, Rajesh; Kundu, R. S.; Punia, R.; Aghamkar, P.; Kishore, N.

    2014-10-01

    Iron bismuth silicate glasses have been successfully synthesized by melt quenching technique. The amorphous nature of the glass samples is ascertained by the XRD patterns. The values of density, molar volume and crystalline volume have been measured and are found to decrease with increase in iron content. The glass transition temperature measured using Differential Scanning Calorimetry (DSC) also varies with increase in Fe2O3 content. The Raman and FTIR spectra of the studied glass system taken at room temperature suggests that Fe2O3 modifies the structure of bismuth silicate glasses and it acts as both network modifier as well as network former. Bismuth also plays the role of both network modifier (BiO6 octahedra) as well as network former (BiO3 pyramids) and SiO2 exists in SiO4 tetrahedral structural units with two non-bridging oxygens. The Hydrogenic excitonic model is found to be applicable to the studied glass compositions. The variation in Urbach energy value observed for the studied glass samples suggests the possibility of increase in the number of glass defects. The metallization criterion for the synthesized glass samples is determined and found to be in the range 0.30-0.38.

  16. Comparative Evaluation of Different Optimization Algorithms for Structural Design Applications

    NASA Technical Reports Server (NTRS)

    Patnaik, Surya N.; Coroneos, Rula M.; Guptill, James D.; Hopkins, Dale A.

    1996-01-01

    Non-linear programming algorithms play an important role in structural design optimization. Fortunately, several algorithms with computer codes are available. At NASA Lewis Research Centre, a project was initiated to assess the performance of eight different optimizers through the development of a computer code CometBoards. This paper summarizes the conclusions of that research. CometBoards was employed to solve sets of small, medium and large structural problems, using the eight different optimizers on a Cray-YMP8E/8128 computer. The reliability and efficiency of the optimizers were determined from the performance of these problems. For small problems, the performance of most of the optimizers could be considered adequate. For large problems, however, three optimizers (two sequential quadratic programming routines, DNCONG of IMSL and SQP of IDESIGN, along with Sequential Unconstrained Minimizations Technique SUMT) outperformed others. At optimum, most optimizers captured an identical number of active displacement and frequency constraints but the number of active stress constraints differed among the optimizers. This discrepancy can be attributed to singularity conditions in the optimization and the alleviation of this discrepancy can improve the efficiency of optimizers.

  17. Ocean Classification of Dynamical Structures Detected by SAR and Spectral Methods

    NASA Astrophysics Data System (ADS)

    Redondo, J. M.; Martinez-Benjamin, J. J.; Tellez, J. D.; Jorge, J.; Diez, M.; Sekula, E.

    2016-08-01

    We discuss a taxonomy of different dynamical features in the ocean surface and provide some eddy and front statistics, as well as describing some events detected by several satellites and even with additional cruise observations and measurements, in the North-west Mediterranean Sea area between 1996 and 2012. The structure of the flows are presented using self-similar traces that may be used to parametrize mixing at both limits of the Rossby Deformation Radius scale, RL. Results show the ability to identify different SAR signatures and at the same time provide calibrations for the different local configurations of vortices, spirals, Langmuir cells, oil spills and tensioactive slicks that eventually allow the study of the self-similar structure of the turbulence. Depending on the surface wind and wave level, and also on the fetch. the bathimetry, the spiral parameters and the resolution of vortical features change. Previous descriptions did not include the new wind and buoyancy features. SAR images also show the turbulence structure of the coastal area and the Regions of Fresh Water Influence (ROFI). It is noteworthy tt such complex coastal field-dependent behavior is strongly influenced by stratification and rotation of the turbulence spectrum is observed only in the range smaller than the local Rossby deformation radius, RL. The measures of diffusivity from buoy or tracer experiments are used to calibrate the behavior of different tracers and pollutants, both natural and man-made in the NW Mediterranean Sea. Thanks to different polarization and intensity levels in ASAR satellite imagery, these can be used to distinguish between natural and man-made sea surface features due to their distinct self-similar and fractal as a function of spill and slick parameters, environmental conditions and history of both oil releases and weather conditions. Eddy diffusivity map derived from SAR measurements of the ocean surface, performing a feature spatial correlation of the

  18. Spectral assignments and structural studies of a warfarin derivative stereoselectively formed by tandem cyclization

    NASA Astrophysics Data System (ADS)

    Velayutham Pillai, M.; Rajeswari, K.; Vidhyasagar, T.

    2015-11-01

    The structural elucidation of a Mannich condensation product of rac-Warfarin with benzaldehyde and methyl amine was carried out using IR, Mass, 1H NMR, 13C NMR, 1H-1H COSY, 1H-13C COSY, DEPT-135, HMBC, NOESY spectra and single crystal X-ray diffraction. Formation of a new pyran ring via a tandem cyclization in the presence of methyl amine was observed. The optimized geometry and HOMO-LUMO energy gap along with other important physical parameters were found by Gaussian 09 program using HF 6-31G (d, p) and B3YLP/DFT 6-31G (d, p) level of theory. The preferred conformation of the piperidine ring in solution state was found to be chair from the NMR spectra. Single crystal X-ray diffraction and optimized geometry (by theoretical study) also confirms the chair conformation in the solid state.

  19. Metallic nano-structures for polarization-independent multi-spectral filters.

    PubMed

    Tang, Yongan; Vlahovic, Branislav; Brady, David Jones

    2011-05-23

    Cross-shaped-hole arrays (CSHAs) are selected for diminishing the polarization-dependent transmission differences of incident plane waves. We investigate the light transmission spectrum of the CSHAs in a thin gold film over a wide range of features. It is observed that two well-separated and high transmission efficiency peaks could be obtained by designing the parameters in the CSHAs for both p-polarized and s-polarized waves; and a nice transmission band-pass is also observed by specific parameters of a CSHA too. It implicates the possibility to obtain a desired polarization-independent transmission spectrum from the CSHAs by designing their parameters. These findings provide potential applications of the metallic nano-structures in optical filters, optical band-pass, optical imaging, optical sensing, and biosensors.

  20. Accretion Disk Structure in Various Spectral States of GRS 1915+105

    NASA Astrophysics Data System (ADS)

    Remillard, Ronald

    2000-09-01

    GRS 1915+105 displays 9 types of light curves that fall in 3 categories. In the steady-hard states, the Fe line is strongest, and there is a steady type of jet. In the soft states, the accretion disk dominates the X-ray spectrum, and we often detect the 67 Hz QPO thought to arise from GR effects in the inner disk. The remaining states show a variety of instability oscillations, some producing violent mass ejections. Progress on all fronts requires high resolution spectra to help interpret the disk structure. We have particular interest in the profiles of broad Fe emission, intending to gain physical insights using theoretical models of Nayakshin et al. With monitoring timescales selected to randomize the 9 states, we request 3 obs likely to sample different conditions in the disk.

  1. A study of the structural and spectral characteristics of free and bound water in kaolinite

    NASA Astrophysics Data System (ADS)

    Kasprzhitskii, A. S.; Lazorenko, G. I.; Sulavko, S. N.; Yavna, V. A.; Kochur, A. G.

    2016-09-01

    The dependence of the Si-O stretching vibration line intensity in the IR spectrum of kaolinite on the humidity of this mineral has been experimentally investigated. The experimental data were interpreted on the basis of density functional theory (DFT) calculations with allowance for the real crystallographic features of the kaolinite sample, determined by structural analysis. Some specific features of the intensity behavior in the plastic state are revealed, which can be used to develop techniques for determining its limits. The differences in the O-H bond lengths and H-O-H angles for the H2O molecules adsorbed by basal surfaces and located in the porous space of the mineral are determined. Based on the DFT data, it was found that bond lengths and bond angles for a water molecule adsorbed on the siloxane surface are systematically smaller than for a water molecule adsorbed on the hydroxyl surface.

  2. Comparing connected structures in ensemble of random fields

    NASA Astrophysics Data System (ADS)

    Rongier, Guillaume; Collon, Pauline; Renard, Philippe; Straubhaar, Julien; Sausse, Judith

    2016-10-01

    Very different connectivity patterns may arise from using different simulation methods or sets of parameters, and therefore different flow properties. This paper proposes a systematic method to compare ensemble of categorical simulations from a static connectivity point of view. The differences of static connectivity cannot always be distinguished using two point statistics. In addition, multiple-point histograms only provide a statistical comparison of patterns regardless of the connectivity. Thus, we propose to characterize the static connectivity from a set of 12 indicators based on the connected components of the realizations. Some indicators describe the spatial repartition of the connected components, others their global shape or their topology through the component skeletons. We also gather all the indicators into dissimilarity values to easily compare hundreds of realizations. Heat maps and multidimensional scaling then facilitate the dissimilarity analysis. The application to a synthetic case highlights the impact of the grid size on the connectivity and the indicators. Such impact disappears when comparing samples of the realizations with the same sizes. The method is then able to rank realizations from a referring model based on their static connectivity. This application also gives rise to more practical advices. The multidimensional scaling appears as a powerful visualization tool, but it also induces dissimilarity misrepresentations: it should always be interpreted cautiously with a look at the point position confidence. The heat map displays the real dissimilarities and is more appropriate for a detailed analysis. The comparison with a multiple-point histogram method shows the benefit of the connected components: the large-scale connectivity seems better characterized by our indicators, especially the skeleton indicators.

  3. Synthesis of two new azo-azomethines; spectral characterization, crystal structures, computational and fluorescence studies

    NASA Astrophysics Data System (ADS)

    Eskikanbur, Sevgi; Sayin, Koray; Kose, Muhammet; Zengin, Huseyin; McKee, Vickie; Kurtoglu, Mukerrem

    2015-08-01

    This study describes the preparation, characterization and the photoluminescence properties of novel azo-azomethines (2-{(E)-[(4-ethylphenyl)imino]methyl}-4-[(E)-phenyldiazenyl]phenol, HL1 and 2-{(E)-[(3-ethylphenyl)imino]methyl}-4-[(E)-phenyldiazenyl]phenol, HL2 dyes). The dyes were characterized by elemental analysis, spectroscopic studies such as IR, 1H and 13C NMR, mass and fluorescence spectra. Molecular structures of the dyes were examined by X-ray diffraction analysis. The molecular structures are mostly similar, differing mainly in the position of the ethyl group and dihedral angles between aromatic rings. X-ray data revealed that both HL1 and HL2 favor phenol-imine tautomer in the solid state. An intramolecular phenol-imine hydrogen bond (O1⋯N1) were observed in both compounds resulting in a S(6) hydrogen bonding motif. Molecular packing of both compounds are determined by π⋯π interactions. Quantum chemical investigation of mentioned molecules were performed by using DFT hybrid function (B3LYP) with 6-31+G(d) basis set. The compounds HL1 and HL1 gave intense light emissions upon irradiation by Ultra-Violet light. The photoluminescence quantum yields and long excited-state lifetimes of the compounds HL1 and HL2 were measured. The azo-azomethine dyes HL1 and HL2 have photoluminescence quantum yields of 34% and 32% and excited-state lifetimes of 3.21 and 2.98 ns, respectively. The photoluminescence intensities and quantum yields of these dyes were dependent on the position of alkyl group on the phenyl ring.

  4. Jupiter's Deep Cloud Structure Revealed Using Keck Observations of Spectrally Resolved Line Shapes

    NASA Technical Reports Server (NTRS)

    Bjoraker, G. L.; Wong, M.H.; de Pater, I.; Adamkovics, M.

    2015-01-01

    Technique: We present a method to determine the pressure at which significant cloud opacity is present between 2 and 6 bars on Jupiter. We use: a) the strength of a Fraunhofer absorption line in a zone to determine the ratio of reflected sunlight to thermal emission, and b) pressure- broadened line profiles of deuterated methane (CH3D) at 4.66 meters to determine the location of clouds. We use radiative transfer models to constrain the altitude region of both the solar and thermal components of Jupiter's 5-meter spectrum. Results: For nearly all latitudes on Jupiter the thermal component is large enough to constrain the deep cloud structure even when upper clouds are present. We find that Hot Spots, belts, and high latitudes have broader line profiles than do zones. Radiative transfer models show that Hot Spots in the North and South Equatorial Belts (NEB, SEB) typically do not have opaque clouds at pressures greater than 2 bars. The South Tropical Zone (STZ) at 32 degrees South has an opaque cloud top between 4 and 5 bars. From thermochemical models this must be a water cloud. We measured the variation of the equivalent width of CH3D with latitude for comparison with Jupiter's belt-zone structure. We also constrained the vertical profile of H2O in an SEB Hot Spot and in the STZ. The Hot Spot is very dry for a probability less than 4.5 bars and then follows the H2O profile observed by the Galileo Probe. The STZ has a saturated H2O profile above its cloud top between 4 and 5 bars.

  5. Crystallization and birefringence studies on fast structural changes followed by non-contact spectral birefringence and Raman spectroscopy techniques

    NASA Astrophysics Data System (ADS)

    Serhatkulu, Toprak Fakr

    2000-11-01

    The structural characteristics of the manufactured polymers such as crystallinity and orientation are controlled by the thermal-deformation history imposed by the processing machinery. Therefore it is essential to monitor these structural characteristics and use the information advantageously to optimize the properties of interest by controlling the process conditions. The focus of this study is to develop robust automated techniques to monitor birefringence and crystallization in real-time. In many of the polymer processing operations involving film stretching where the polymer undergoes a series of thermal deformation treatments, the quantitative changes that take place during the course of these processing operations is poorly understood partly as a result of very rapid structural changes that occur when the polymer's initial condition is not isotropic melt of isotropic solid. There is a great need to quantify the kinetics of the structural changes from preoriented/partially-crystallized states. As part of this dissertation, the birefringence development of preoriented polyethylene terephthalate (PET) films is monitored on-line by the developed spectral birefringence technique with the intent of simulating the heat-setting stage of a tenter film stretching process. Theoretical improvements, software development and optimization, and the equipment design and construction are some of the major tasks accomplished in this dissertation. The automated spectral birefringence technique not only allows the measurement of retardations to very high values, but also enables one to detect the changes in the trend in birefringence (such as a decrease as a result of relaxation, or an increase as a result of crystallization) and to investigate changes that occur very rapidly in the order of a few hundred milliseconds. The effects of stretching conditions on the kinetics of the structural changes in PET films were also investigated using characterization techniques such as

  6. Spectral structure of pressure measurements made in a combustion duct. [jet engine noise

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

    A model for acoustic plane wave propagation in a combustion duct through a confined, flowing gas containing soot particles is presented. The model takes into account only heat transfer between the gas and soot particles. As a result, the model depends on only a single parameter which can be written as the ratio of the soot particle thermal relaxation time to the soot particle mass fraction. The model yields expressions for the attenuation and dispersion of the plane wave which depends only on this single parameter. The model was used to calculate pressure spectra in a combustion duct. The results were compared with measured spectra. For particular values of the single free parameter, the calculated spectra resemble the measured spectra. Consequently, the model, to this extent, explains the experimental measurements and provides some insight into the number and type of particles.

  7. Spectral and electrical diagnosis of complex space-charge structures excited by a spherical grid cathode with orifice

    NASA Astrophysics Data System (ADS)

    Schrittwieser, R. W.; Ionita, C.; Teodorescu-Soare, C. T.; Vasilovici, O.; Gurlui, S.; Irimiciuc, S. A.; Dimitriu, D. G.

    2017-04-01

    Optical emission spectroscopy and Langmuir probes were used to diagnose complex space-charge structures that appear inside and around a spherical grid with orifice applying a negative voltage below a critical value to it. Measurements (through the orifice) delivered the axial profiles of plasma potential, electron temperature and density, and of the densities of excited atoms and ions. Thereby the formation of a double layer was found in the region near the orifice with a potential drop close to the ionisation potential of the applied gas, confirming the presence of a fireball in that region (also evidenced by visual observation), i.e. of a quasi-spherical bright plasma region consisting of a positive core (an ion-rich plasma) confined by a double layer. Spectral investigations confirmed the presence of high ion density inside the spherical grid (due to the hollow cathode effect), while outside the grid a transition region with a strong rate of ionisation and excitation processes appears. Information on the nonlinear dynamics of this space-charge structure was obtained from the analysis of the oscillations of the discharge current, as well as of the floating potential inside and outside the spherical grid. Dedicated to Hans Pécseli at the occasion of his 70th birthday, an extraordinary plasma physicist and a wonderful, noble and warm-hearted friend for more than 40 years.

  8. The molecular structure of difluoroisocyanato silane: A combined microwave spectral and theoretical study

    NASA Astrophysics Data System (ADS)

    Guirgis, Gamil A.; Wang, Zichao; Lirjoni, Jonel; Palmer, Michael H.; Obenchain, Daniel A.; Peebles, Rebecca A.; Peebles, Sean A.

    2010-11-01

    The microwave (MW) spectrum of HF 2SiNCO (1) has been obtained and analyzed in the I r representation for C S symmetry. The rotational constants (RC) are: A 7111.28104(179), B 1565.77581(49) and C 1347.52275(77) MHz; the centrifugal distortion constants are: Δ J 2.661(11), Δ JK 455.44(25), δ J 0.4237(51), ϕ K -54.96(29) kHz; the 14N nuclear quadrupole coupling constants are: χ aa +1.8833(27) and ( χ bb - χ cc) -0.0214(58) MHz. The low value for ( χ bb - χ cc) implies a nearly linear SiNC structure, while the experimental A value is only consistent with cis-HSiNC and trans-SiNCO orientations. The MW analysis was assisted by calculations of the equilibrium structure. Whilst small bases give a linear SiNCO skeleton, a 6-311G ++ (3df,3pd) basis set calculation shows that the molecule is quasi-linear for all four methodologies: DFT, MP2, MP4 or CCSD(T). However, all these methods find the lowest energy conformer has trans-HSiNC and trans-SiNCO dihedral angles, although the energy difference is very small. The internal rotation barrier for the HF 2Si group is less than 1 cm -1, with the lower energy conformer having a trans-HSiNC moiety. The calculated SiNC angles for the cis-HSiNC conformer are: 171.2 (B3LYP), 167.7 (MP2), 154.9 (MP4) and 154.6° (CCSD(T)), with differences up to 9° (MP2) in the trans-series. The potential energy (PE) surface for SiNC bending ( x) is unsymmetrical, but the differences from a symmetric form are very small. A B3LYP study leads to a polynomial fit of the SiNC angle ( x, radians) with the energy ( E, cm -1), where E = 1993(536) x2 - 422(134) x4 + 27(10) x6 - 0.5(2) x8; the alternating signs indicate a double minimum potential. We have re-determined the PE surfaces for silyl group rotation for several other isocyanates using similar methods.

  9. Synthesis, structure, spectral, thermal analyses and DFT calculation of a hydrogen bonded crystal: 2-Aminopyrimidinium dihydrogenphosphate monohydrate

    NASA Astrophysics Data System (ADS)

    Thangarasu, S.; Suresh Kumar, S.; Athimoolam, S.; Sridhar, B.; Asath Bahadur, S.; Shanmugam, R.; Thamaraichelvan, A.

    2014-09-01

    A proton transfer complex of 2-aminopyrimidine with phosphoric acid was synthesized and crystallized. Single crystal X-ray studies, the vibrational spectral analysis using Laser Raman and FT-IR spectroscopy in the range of 4000-400 cm-1, UV-Vis-NIR studies and thermogravimetric analyses were carried out in the solid crystalline form. The single crystal X-ray studies shows that the crystal packing is dominated by Nsbnd H⋯O and Osbnd H⋯O hydrogen bonds leading to a hydrogen bonded ensemble. The two dimensional cationic layers, connected through the centrosymmetric anionic dimer of R22(8) motif, is extending along ab plane of the crystal leading to zig-zag infinite chain C21(6) and C22(6) motifs. To investigate the strength of the hydrogen bonds, vibrational spectral studies were adopted and the shifting of bands due to the intermolecular interactions were analyzed. Density Functional Theory (DFT) using the B3LYP function with the 6-311++G(d,p) basis set was applied to the solid state molecular geometry obtained from single crystal X-ray studies. The optimized molecular geometry and computed vibrational spectra are compared with experimental results which shows appreciable agreement. NBO analysis has been carried out by DFT level. In this study explains charge delocalization of the present molecule which shows the possible biological/pharmaceutical activity of the molecule. The number of normal modes were also attempted by the factor group analysis method. It is evident that the influence of extensive intermolecular hydrogen bonds reduces the Td symmetry of the phosphate anion to the lower C2v symmetry. The existence of exothermic peaks in DTA iterate the breaking of intermolecular hydrogen bonds and the phase change of the crystal. The presence of water molecule is also confirmed in the thermal analyses.

  10. Platform to investigate aqueous outflow system structure and pressure-dependent motion using high-resolution spectral domain optical coherence tomography

    PubMed Central

    Hariri, Sepideh; Johnstone, Murray; Jiang, Yi; Padilla, Steven; Zhou, Zhehai; Reif, Roberto; Wang, Ruikang K.

    2014-01-01

    Abstract. The aqueous outflow system (AOS) is responsible for maintaining normal intraocular pressure (IOP) in the eye. Structures of the AOS have an active role in regulating IOP in healthy eyes and these structures become abnormal in the eyes with glaucoma. We describe a newly developed system platform to obtain high-resolution images of the AOS structures. By incorporating spectral domain optical coherence tomography (SD-OCT), the platform allows us to systematically control, image, and quantitate the responses of AOS tissue to pressure with a millisecond resolution of pulsed flow. We use SD-OCT to image radial limbal segments from the surface of the trabecular meshwork (TM) with a spatial resolution of ∼5  μm in ex vivo nonhuman primate eyes. We carefully insert a cannula into Schlemm’s canal (SC) to control both pressures and flow rates. The experimental results demonstrate the capability of the platform to visualize the unprecedented details of AOS tissue components comparable to that delivered by scanning electron microscopy, as well as to delineate the complex pressure-dependent relationships among the TM, structures within the SC, and collector channel ostia. The described technique provides a new means to characterize the anatomic and pressure-dependent relationships of SC structures, particularly the active motion of collagenous elements at collector channel ostia; such relationships have not previously been amenable to study. Experimental findings suggest that continuing improvements in the OCT imaging of the AOS may provide both insights into the glaucoma enigma and improvements in its management. PMID:25349094

  11. Synthesis, crystal structure, spectral analysis and DFT computational studies on a novel isoindoline derivative

    NASA Astrophysics Data System (ADS)

    Evecen, Meryem; Duru, Gülcan; Tanak, Hasan; Ağar, Ayşen Alaman

    2016-08-01

    The isoindoline compound, 2-(3-chloro-4-(4-chlorophenoxy)phenyl)isoindoline-1,3-dione, has been synthesized and characterized by FT-IR, UV-Vis and X-ray single-crystal determination. The compound crystallizes in the monoclinic space group P21/c with a = 20.441 (3) Å, b = 4.0258 (4) Å, c = 23.836 (2) Å, β = 121.918 (7)° and Z = 4. The molecular structure and vibrational frequencies in the ground state were calculated using the density functional theory method (B3LYP) with 6-311++G(d,p) basis set. The results obtained from the optimization and vibrational analyses are agree with the experimental results. Using the TD-DFT method, electronic absorption spectra have been calculated, and they are compatible with the experimental ones. The electric dipole moment (μ), polarizability (α) and the first hyperpolarizability (β) values of the compound were calculated theoretically. The first hyperpolarizability of the molecule shows that the compound can be a good candidate of nonlinear optical material. In addition, DFT calculations of the compound, atomic charges, molecular electrostatic potential and thermodynamic properties were also performed at B3LYP/6-311++G(d,p) level of theory.

  12. Atomic structure calculations and identification of EUV and SXR spectral lines in Sr XXX

    NASA Astrophysics Data System (ADS)

    Goyal, Arun; Khatri, Indu; Aggarwal, Sunny; Singh, A. K.; Mohan, Man

    2015-08-01

    We report an extensive theoretical study of atomic data for Sr XXX in a wide range with L-shell electron excitations to the M-shell. We have calculated energy levels, wave-function compositions and lifetimes for lowest 113 fine structure levels and wavelengths of an extreme Ultraviolet (EUV) and soft X-ray (SXR) transitions. We have employed multi-configuration Dirac Fock method (MCDF) approach within the framework of Dirac-Coulomb Hamiltonian including quantum electrodynamics (QED) and Breit corrections. We have also presented the radiative data for electric and magnetic dipole (E1, M1) and quadrupole (E2, M2) transitions from the ground state. We have made comparisons with available energy levels compiled by NIST and achieve good agreement. But due to inadequate data in the literature, analogous relativistic distorted wave calculations have also been performed using flexible atomic code (FAC) to assess the reliability and accuracy of our results. Additionally, we have provided new atomic data for Sr XXX which is not published elsewhere in the literature and we believe that our results may be beneficial in fusion plasma research and astrophysical investigations and applications.

  13. Facile synthesis, structural elucidation and spectral analysis of pyrrole 4-imidazole derivatives

    NASA Astrophysics Data System (ADS)

    Singh, R. N.; Rawat, Poonam; Baboo, Vikas

    2015-12-01

    In this work pyrrole 4-imidazole derivatives (3A-3D): benzimidazoles and pyrrole 4-imidazoline have been synthesized by condensation, cyclization and oxidation of ethyl 4-formyl-3,5-dimethyl-1H-pyrrole carboxylate and phenylene diamine derivatives/ethylene diamine. The structure of these biheterocyclic compounds have been derived by elemental and spectroscopic - IR, UV, MS, 1H and 13C NMR analysis as well as theoretical study. The static first hyperpolarizability, β0 values for pyrrole 4-imidazole derivatives, (3A-3D) have been calculated as 10.901 × 10-31, 19.607 × 10-31, 40.323 × 10-31, 5.686 × 10-31 esu, respectively. The gradual increase in β0 value of synthesized pyrrole-benzimidazole derivatives from 3A to 3C is due to addition of acceptors -Cl atom in 3B to -NO2 group in 3C on benzimidazole side. The experimental absorption spectra found to be in UV region and the high β0 values show that the synthesized pyrrole-imidazoles are suitable as non-linear optical (NLO) materials.

  14. Comparative jet wake structure and swimming performance of salps.

    PubMed

    Sutherland, Kelly R; Madin, Laurence P

    2010-09-01

    Salps are barrel-shaped marine invertebrates that swim by jet propulsion. Morphological variations among species and life-cycle stages are accompanied by differences in swimming mode. The goal of this investigation was to compare propulsive jet wakes and swimming performance variables among morphologically distinct salp species (Pegea confoederata, Weelia (Salpa) cylindrica, Cyclosalpa sp.) and relate swimming patterns to ecological function. Using a combination of in situ dye visualization and particle image velocimetry (PIV) measurements, we describe properties of the jet wake and swimming performance variables including thrust, drag and propulsive efficiency. Locomotion by all species investigated was achieved via vortex ring propulsion. The slow-swimming P. confoederata produced the highest weight-specific thrust (T=53 N kg(-1)) and swam with the highest whole-cycle propulsive efficiency (eta(wc)=55%). The fast-swimming W. cylindrica had the most streamlined body shape but produced an intermediate weight-specific thrust (T=30 N kg(-1)) and swam with an intermediate whole-cycle propulsive efficiency (eta(wc)=52%). Weak swimming performance variables in the slow-swimming C. affinis, including the lowest weight-specific thrust (T=25 N kg(-1)) and lowest whole-cycle propulsive efficiency (eta(wc)=47%), may be compensated by low energetic requirements. Swimming performance variables are considered in the context of ecological roles and evolutionary relationships.

  15. Hospital profitability and capital structure: a comparative analysis.

    PubMed Central

    Valvona, J; Sloan, F A

    1988-01-01

    This article compares the financial performance of hospitals by ownership type and of five publicly traded hospital companies with other industries, using such indicators as profit margins, return on equity (ROE) and total capitalization, and debt-to-equity ratios. We also examine stock returns to investors for the five hospital companies versus other industries, as well as the relative roles of debt and equity in new financing. Investor-owned hospitals had substantially greater margins and ROE than did other hospital types. In 1982, investor-owned chain hospitals had a ROE of 26 percent, 18 points above the average for all hospitals. Stock returns on the five selected hospital companies were more than twice as large as returns on other industries between 1972 and 1983. However, after 1983, returns for these companies fell dramatically in absolute terms and relative to other industries. We also found investor-owned hospitals to be much more highly levered than their government and voluntary counterparts, and more highly levered than other industries as well. PMID:3403274

  16. Synthesis, spectral, and structural characterizations of imidazole oxalato molybdenum(IV/V/VI) complexes.

    PubMed

    Chen, Quan-Liang; Chen, Hong-Bin; Cao, Ze-Xing; Zhou, Zhao-Hui

    2013-02-07

    Substitutions of trans-Na(Him)[Mo(2)O(4)(ox)(2)(H(2)O)(2)]·H(2)O (1) and trans-(Him)(2)[Mo(2)O(4)(ox)(2)(H(2)O)(2)] (2) with imidazole result in the formation of the mixed-ligand molybdenum complexes cis-Na(2)[Mo(2)O(4)(ox)(2)(im)(2)]·4.5H(2)O (3), cis-K(2)[Mo(2)O(4)(ox)(2)(im)(2)]·3H(2)O (4), respectively (H(2)ox = oxalic acid; im = imidazole). Further reduction of cis-K(2)[Mo(2)O(4)(ox)(2)(im)(2)]·3H(2)O (4) gives a trinuclear molybdenum(IV) complex K(Him)[Mo(3)O(4)(ox)(3)(im)(3)]·3H(2)O (5), which contains an incomplete cubane cluster [Mo(IV)(3)O(4)](4+). Two novel trinuclear mixed-valence imidazole compounds [Mo(3)O(8)(im)(4)](im)·H(2)O (6) and [Mo(3)O(8)(im)(4)]·H(2)O (7) were obtained by the reduction of (Him)(4)[Mo(8)O(26)(im)(2)] (8). Both 6 and 7 contain a novel Mo(VI)O(4)(Mo(V)(2)O(4)) center, where the [Mo(V)(2)O(4)](2+) unit is linked by [Mo(VI)O(4)](2-) anion. The Mo-Mo bond distances in 1-7 decrease with the decrease of oxidation state of molybdenum. Solid and solution NMR spectra show that imidazole molybdenum compounds 6-8 fully dissociate in solution, where solvated imidazole and imidazolium groups in 6 and 8 could be served as internal references in their solid (13)C NMR spectra. Furthermore, mixed-ligand molybdenum species 3 and 4 are stable in water. Stabilities of 3 and 4 in solution may be attributed to the strong coordination of bidentate oxalate and the formation of hydrogen bond. Dimers 2 and 4 display quasi-reversible redox process, while trimer 6 is irreversible. Bond valence calculations for 1-8 are consistent with their oxidation states of molybdenum atoms. Calculation of the oxidation state in recent structure of iron molybdenum cofactor [MoFe(7)S(9)C(R-homocit)] (FeMo-co) is 3.318.

  17. Structures, stabilities and spectral properties of borospherene B44(-) and metalloborospherenes MB44(0/-) (M = Li, Na, and K).

    PubMed

    Li, Shixiong; Zhang, Zhengping; Long, Zhengwen; Qin, Shuijie

    2017-01-10

    Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations are carried out to study the stabilities, photoelectron, infrared, Raman and electronic absorption spectra of borospherene B44(-) and metalloborospherenes MB44(0/-) (M = Li, Na, and K). It is found that all atoms can form stable exohedral metalloborospherenes M&B44(0/-), whereas only Na and K atoms can be stably encapsulated inside B44(0/-) cage. In addition, relative energies of these metalloborospherenes suggest that Na and K atoms favor exohedral configuration. Importantly, doping of metal atom can modify the stabilities of B44 with different structures, which provides a possible route to produce stable boron clusters or metalloborospherenes. The calculated results suggest that B44 tends to get electrons from the doped metal. Metalloborospherenes MB44(-) are characterized as charge-transfer complexes (M(2+)B44(2-)), where B44 tends to get two electrons from the extra electron and the doped metal, resulting in similar features with anionic B44(2-). In addition, doping of metal atom can change the spectral features, such as blueshift or redshift and weakening or strengthening of characteristic peaks, since the extra metal atom can modify the electronic structure. The calculated spectra are readily compared with future spectroscopy measurements and can be used as fingerprints to identify B44(-) and metalloborospherenes.

  18. Structures, stabilities and spectral properties of borospherene B44‑ and metalloborospherenes MB440/‑ (M = Li, Na, and K)

    NASA Astrophysics Data System (ADS)

    Li, Shixiong; Zhang, Zhengping; Long, Zhengwen; Qin, Shuijie

    2017-01-01

    Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations are carried out to study the stabilities, photoelectron, infrared, Raman and electronic absorption spectra of borospherene B44‑ and metalloborospherenes MB440/‑ (M = Li, Na, and K). It is found that all atoms can form stable exohedral metalloborospherenes M&B440/‑, whereas only Na and K atoms can be stably encapsulated inside B440/‑ cage. In addition, relative energies of these metalloborospherenes suggest that Na and K atoms favor exohedral configuration. Importantly, doping of metal atom can modify the stabilities of B44 with different structures, which provides a possible route to produce stable boron clusters or metalloborospherenes. The calculated results suggest that B44 tends to get electrons from the doped metal. Metalloborospherenes MB44‑ are characterized as charge-transfer complexes (M2+B442‑), where B44 tends to get two electrons from the extra electron and the doped metal, resulting in similar features with anionic B442‑. In addition, doping of metal atom can change the spectral features, such as blueshift or redshift and weakening or strengthening of characteristic peaks, since the extra metal atom can modify the electronic structure. The calculated spectra are readily compared with future spectroscopy measurements and can be used as fingerprints to identify B44‑ and metalloborospherenes.

  19. Integration of spectral domain optical coherence tomography with microperimetry generates unique datasets for the simultaneous identification of visual function and retinal structure in ophthalmological applications

    NASA Astrophysics Data System (ADS)

    Koulen, Peter; Gallimore, Gary; Vincent, Ryan D.; Sabates, Nelson R.; Sabates, Felix N.

    2011-06-01

    Conventional perimeters are used routinely in various eye disease states to evaluate the central visual field and to quantitatively map sensitivity. However, standard automated perimetry proves difficult for retina and specifically macular disease due to the need for central and steady fixation. Advances in instrumentation have led to microperimetry, which incorporates eye tracking for placement of macular sensitivity values onto an image of the macular fundus thus enabling a precise functional and anatomical mapping of the central visual field. Functional sensitivity of the retina can be compared with the observed structural parameters that are acquired with high-resolution spectral domain optical coherence tomography and by integration of scanning laser ophthalmoscope-driven imaging. Findings of the present study generate a basis for age-matched comparison of sensitivity values in patients with macular pathology. Microperimetry registered with detailed structural data performed before and after intervention treatments provides valuable information about macular function, disease progression and treatment success. This approach also allows for the detection of disease or treatment related changes in retinal sensitivity when visual acuity is not affected and can drive the decision making process in choosing different treatment regimens and guiding visual rehabilitation. This has immediate relevance for applications in central retinal vein occlusion, central serous choroidopathy, age-related macular degeneration, familial macular dystrophy and several other forms of retina related visual disability.

  20. Structures, stabilities and spectral properties of borospherene B44− and metalloborospherenes MB440/− (M = Li, Na, and K)

    PubMed Central

    Li, Shixiong; Zhang, Zhengping; Long, Zhengwen; Qin, Shuijie

    2017-01-01

    Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations are carried out to study the stabilities, photoelectron, infrared, Raman and electronic absorption spectra of borospherene B44− and metalloborospherenes MB440/− (M = Li, Na, and K). It is found that all atoms can form stable exohedral metalloborospherenes M&B440/−, whereas only Na and K atoms can be stably encapsulated inside B440/− cage. In addition, relative energies of these metalloborospherenes suggest that Na and K atoms favor exohedral configuration. Importantly, doping of metal atom can modify the stabilities of B44 with different structures, which provides a possible route to produce stable boron clusters or metalloborospherenes. The calculated results suggest that B44 tends to get electrons from the doped metal. Metalloborospherenes MB44− are characterized as charge-transfer complexes (M2+B442−), where B44 tends to get two electrons from the extra electron and the doped metal, resulting in similar features with anionic B442−. In addition, doping of metal atom can change the spectral features, such as blueshift or redshift and weakening or strengthening of characteristic peaks, since the extra metal atom can modify the electronic structure. The calculated spectra are readily compared with future spectroscopy measurements and can be used as fingerprints to identify B44− and metalloborospherenes. PMID:28071694

  1. A comparative analysis of spectral exponent estimation techniques for 1/fβ processes with applications to the analysis of stride interval time series

    PubMed Central

    Schaefer, Alexander; Brach, Jennifer S.; Perera, Subashan; Sejdić, Ervin

    2013-01-01

    Background The time evolution and complex interactions of many nonlinear systems, such as in the human body, result in fractal types of parameter outcomes that exhibit self similarity over long time scales by a power law in the frequency spectrum S(f) = 1/fβ. The scaling exponent β is thus often interpreted as a “biomarker” of relative health and decline. New Method This paper presents a thorough comparative numerical analysis of fractal characterization techniques with specific consideration given to experimentally measured gait stride interval time series. The ideal fractal signals generated in the numerical analysis are constrained under varying lengths and biases indicative of a range of physiologically conceivable fractal signals. This analysis is to complement previous investigations of fractal characteristics in healthy and pathological gait stride interval time series, with which this study is compared. Results The results of our analysis showed that the averaged wavelet coefficient method consistently yielded the most accurate results. Comparison with Existing Methods: Class dependent methods proved to be unsuitable for physiological time series. Detrended fluctuation analysis as most prevailing method in the literature exhibited large estimation variances. Conclusions The comparative numerical analysis and experimental applications provide a thorough basis for determining an appropriate and robust method for measuring and comparing a physiologically meaningful biomarker, the spectral index β. In consideration of the constraints of application, we note the significant drawbacks of detrended fluctuation analysis and conclude that the averaged wavelet coefficient method can provide reasonable consistency and accuracy for characterizing these fractal time series. PMID:24200509

  2. Synthesis, spectral, crystal structure, thermal behavior, antimicrobial and DNA cleavage potential of two octahedral cadmium complexes: A supramolecular structure

    NASA Astrophysics Data System (ADS)

    Montazerozohori, M.; Musavi, S. A.; Masoudiasl, A.; Naghiha, A.; Dusek, M.; Kucerakova, M.

    2015-02-01

    Two new cadmium(II) complexes with the formula of CdL2(NCS)2 and CdL2(N3)2 (in which L is 2,2-dimethyl-N,N‧-bis-(3-phenyl-allylidene)-propane-1,3-diamine) have been synthesized and characterized by elemental analysis, molar conductivity measurements, FT/IR, UV-Visible, 1H and 13C NMR spectra and X-ray studies. The crystal structure analysis of CdL2(NCS)2 indicated that it crystallizes in orthorhombic system with space group of Pbca. Two Schiff base ligands are bonded to cadmium(II) ion as N2-donor chelate. Coordination geometry around the cadmium ion was found to be partially distorted octahedron. The Cd-Nimine bond distances are found in the range of 2.363(2)-2.427(2) Å while the Cd-Nisothiocyanate bond distances are 2.287(2) Å and 2.310(2) Å. The existence of C-H⋯π and C-H⋯S interactions in the CdL2(NCS)2 crystal leads to a supramolecular structure in its network. Then cadmium complexes were screened in vitro for their antibacterial and antifungal activities against two Gram-negative and two Gram-positive bacteria and also against Candida albicans as a fungus. Moreover, the compounds were subjected for DNA-cleavage potential by gel electrophoresis method. Finally thermo-gravimetric analysis of the complexes was applied for thermal behavior studies and then some thermo-kinetics activation parameters were evaluated.

  3. Complex Spatio-Spectral Structure of Diffuse X-ray Emission in the Central 20 Parsecs of the Milky Way

    NASA Astrophysics Data System (ADS)

    Park, S.; Baganoff, F. K.; Bautz, M. W.; Garmire, G. P.; Maeda, Y.; Morris, M.; Muno, M. P.

    2002-12-01

    Over the last three years, the Galactic center region has been monitored with a series of the Chandra/ACIS observations. Besides the target object Sgr A*, the massive Galactic black hole candidate, the surrounding diffuse X-ray emission has been detected within the ~17' x 17' ACIS field of view. As of 2002 June, combining 11 GTO and GO observations, the total effective exposure reaches ~590 ks, which reveals the details of the faint diffuse X-ray emission with significant photon statistics. We here present early results from the imaging/spectral analyses of these data. The ``true-color'' X-ray images of this region indicate that the diffuse X-ray emission features have complex spatio-spectral structures represented by various atomic line emission and hard continuum. We construct the equivalent width (EW) images for the detected elemental species Si, S, Ar, Ca, and Fe in order to map the distributions of these atomic emission lines in the Galactic center. We detect strong enhancements of He-like Fe within the ~1.3' diameter region to the immediate east of Sgr A*. This is most likely emission from the highly ionized Fe associated with the recently X-ray identified supernova remnant (SNR) Sgr A East. A large-scale enhancement of the 6.4 keV Fe EW in the north-east of Sgr A* is in general spatially coincident with the molecular cloud M-0.02-0.07, which may be interpreted as emission from the X-ray reflection nebulae or fast-moving SN ejecta fragments. In the soft band (1.5 - 4.5 keV), we detect a network of loop-like structures with a few arcmin angular scales around the Galactic center. The soft X-ray loop in the southeast of Sgr A* is identified with the Galactic radio SNR G359.92-0.09, where we detect thermal emission interior to the soft X-ray loops. We detect a bright non-thermal X-ray knot as a part of the southwest boundary of G359.92-0.09 which is spatially coincident with a bright radio knot of the SNR. The best-fit power law spectrum appears harder than

  4. Interaction of anisole with 3α-hydroxy-5β-cholan-24-oic acid macrolides. Part 1. Comparative 1H NMR spectral investigation

    NASA Astrophysics Data System (ADS)

    Lappalainen, Kari V.; Kolehmainen, Erkki T.; Šaman, David

    1995-08-01

    1H NMR spectral investigation on the interaction of anisole (methoxybenzene) with five different (varying by ring size and substitution) cyclic 3α-hydroxy-5β-cholan-24-oic acid macrolides were performed. For 3α-hydroxy-5β-cholan-24-oic acid (lithocholic acid) macrolides (from triolide to pentolide) no effect was observed. In contrast, for 7α-trifluoroacetyloxy (7α-TFA) substituted lithocholate triolide obtained from chenodeoxycholic acid and for 12α-trifluoroacetyloxy (12α-TFA) substituted lithocholate triolide obtained from deoxycholic acid, clear site specific effects were observed. In the case of the 7α-TFA derivative, the aromatic guest causes the strongest up-field shift on the angular methyl 19 at the A/B ring junction of the steroid unit, and in 12α-TFA isomer the strongest effect is directed at the angular methyl 18 located at the C/D ring junction of the steroid skeleton. These findings are discussed in terms of steric factors and the size and flexibility of the cavity of the host molecule. Molecular mechanics is used in modeling the structures of three triolides.

  5. Spectral and Spread Spectral Teleportation

    SciTech Connect

    Humble, Travis S

    2010-01-01

    We report how quantum information encoded into the spectral degree of freedom of a single-photon state is teleported using a finite spectrally entangled biphoton state. We further demonstrate how the bandwidth of a teleported waveform can be controllably and coherently dilated using a spread spectral variant of teleportation. We present analytical fidelities for spectral and spread spectral teleportation when complex-valued Gaussian states are prepared using a proposed experimental approach, and we discuss the utility of these techniques for integrating broad-bandwidth photonic qubits with narrow-bandwidth receivers in quantum communication systems.

  6. Synthesis, electronic structure and spectral fluorescent properties of vinylogous merocyanines derived from 1,3-dialkyl-benzimidazole and malononitrile

    NASA Astrophysics Data System (ADS)

    Kulinich, Andrii V.; Mikitenko, Elena K.; Ishchenko, Alexander A.

    2017-01-01

    A vinylogous series of merocyanines were synthesized with 1,3-dibutyl-benzimidazole and malononitrile residues as the donor and acceptor terminal groups. These dyes do not comprise carbonyl groups, which are prone to the strong specific solvation by polar solvents up to hydrogen bond formation, and nevertheless they possess distinct reversed solvatochromism, i.e. their molecules have very high dipolarity. At that, they are soluble in a wide range of solvents from n-hexane to ethanol and do not aggregate readily. They were studied thoroughly by UV/Vis, fluorescence, IR, and NMR spectroscopy methods. Their structure and spectral properties in the ground and excited fluorescent states were modelled at the DFT level both in vacuum and in solvents of various polarities by using the PCM solvent field simulation. The calculations were performed using several hybrid functionals (B3LYP, CAM-B3LYP, and wB97XD) and the split-valence 6-31G (d,p) basis set.

  7. Spectral, structural, optical and dielectrical studies of UV irradiated Rose Bengal thin films prepared by spin coating technique

    NASA Astrophysics Data System (ADS)

    Zeyada, H. M.; Youssif, M. I.; El-Ghamaz, N. A.; Aboderbala, M. E. O.

    2017-02-01

    Optical properties of pristine and UV irradiated Rose Bengal (RB) films have been investigated using transmittance and reflectance methods. The refractive index(n) and extinction coefficient (k) have been calculated from the absolute values of transmission and reflection spectrum. Single oscillator parameters and Drude model of free carrier absorption have been applied for analysis of the refractive index dispersion. Within the frame work of the band-to-band electron transitions theory; the fundamental absorption edge data were analyzed. Our results suggest that thickness of RB films has no effect on the absorption or the refractive indices in the investigated thicknesses range and within the experimental error. Structural transformation of films from amorphous to polycrystalline has been observed upon UV irradiation. Accordingly, the decreases of all of the absorption coefficient, the energy gap and the refractive index of RB films have been detected. Furthermore, the dependence of the optical functions on UV exposure times has been discussed based on the spectral distribution of the dielectric constant.

  8. Spectral clustering with epidemic diffusion

    NASA Astrophysics Data System (ADS)

    Smith, Laura M.; Lerman, Kristina; Garcia-Cardona, Cristina; Percus, Allon G.; Ghosh, Rumi

    2013-10-01

    Spectral clustering is widely used to partition graphs into distinct modules or communities. Existing methods for spectral clustering use the eigenvalues and eigenvectors of the graph Laplacian, an operator that is closely associated with random walks on graphs. We propose a spectral partitioning method that exploits the properties of epidemic diffusion. An epidemic is a dynamic process that, unlike the random walk, simultaneously transitions to all the neighbors of a given node. We show that the replicator, an operator describing epidemic diffusion, is equivalent to the symmetric normalized Laplacian of a reweighted graph with edges reweighted by the eigenvector centralities of their incident nodes. Thus, more weight is given to edges connecting more central nodes. We describe a method that partitions the nodes based on the componentwise ratio of the replicator's second eigenvector to the first and compare its performance to traditional spectral clustering techniques on synthetic graphs with known community structure. We demonstrate that the replicator gives preference to dense, clique-like structures, enabling it to more effectively discover communities that may be obscured by dense intercommunity linking.

  9. Emission intensity in the visible and IR spectral ranges from Si-based structures formed by direct bonding with simultaneous doping with erbium (Er) and europium (Eu)

    SciTech Connect

    Mezdrogina, M. M. Kostina, L. S.; Beliakova, E. I.; Kuzmin, R. V.

    2013-09-15

    The photo- and electroluminescence spectra of silicon-based structures formed by direct bonding with simultaneous doping with rare-earth metals are studied. It is shown that emission in the visible and IR spectral ranges can be obtained from n-Si:Er/p-Si and n-Si:Eu/p-Si structures fabricated by the method suggested in the study. The results obtained make this method promising for the fabrication of optoelectronic devices.

  10. Comparative study of Poincaré plot analysis using short electroencephalogram signals during anaesthesia with spectral edge frequency 95 and bispectral index.

    PubMed

    Hayashi, K; Yamada, T; Sawa, T

    2015-03-01

    The return or Poincaré plot is a non-linear analytical approach in a two-dimensional plane, where a timed signal is plotted against itself after a time delay. Its scatter pattern reflects the randomness and variability in the signals. Quantification of a Poincaré plot of the electroencephalogram has potential to determine anaesthesia depth. We quantified the degree of dispersion (i.e. standard deviation, SD) along the diagonal line of the electroencephalogram-Poincaré plot (named as SD1/SD2), and compared SD1/SD2 values with spectral edge frequency 95 (SEF95) and bispectral index values. The regression analysis showed a tight linear regression equation with a coefficient of determination (R(2) ) value of 0.904 (p < 0.0001) between the Poincaré index (SD1/SD2) and SEF95, and a moderate linear regression equation between SD1/SD2 and bispectral index (R(2)  = 0.346, p < 0.0001). Quantification of the Poincaré plot tightly correlates with SEF95, reflecting anaesthesia-dependent changes in electroencephalogram oscillation.

  11. Comparative analysis of mt LSU rRNA secondary structures of Odonates: structural variability and phylogenetic signal.

    PubMed

    Misof, B; Fleck, G

    2003-12-01

    Secondary structures of the most conserved part of the mt 16S rRNA gene, domains IV and V, have been recently analysed in a comparative study. However, full secondary structures of the mt LSU rRNA molecule are published for only a few insect species. The present study presents full secondary structures of domains I, II, IV and V of Odonates and one representative of mayflies, Ephemera sp. The reconstructions are based on a comparative approach and minimal consensus structures derived from sequence alignments. The inferred structures exhibit remarkable similarities to the published Drosophila melanogaster model, which increases confidence in these structures. Structural variance within Odonates is homoplastic, and neighbour-joining trees based on tree edit distances do not correspond to any of the phylogenetically expected patterns. However, despite homoplastic quantitative structural variation, many similarities between Odonates and Ephemera sp. suggest promising character sets for higher order insect systematics that merit further investigations.

  12. Spectral distribution of the open-circuit voltage in pCdTe-nCdTe-nCdS film structures

    NASA Astrophysics Data System (ADS)

    Mirsagatov, Sh. A.; Sabirob, K.; Muzafarova, S. A.

    The spectral distribution of the open-circuit voltage of pCdTe-nCdTe-nCdS film structures is determined experimentally in order to assess the contributions of the various barriers of the structure to the generation of the photo-emf. An analysis of the spectral dependence of the open-circuit voltage indicates that the main sensitivity region of the structure corresponds to the photon energy range 1.46-2.3 eV; i.e., the energy of photoactive photons is equal to or greater than the width of the forbidden zone of CdTe (1.46 eV) and less than the width of the forbidden zone of CdS (2.4 eV). The greatest contribution to photo-emf generation is made by the homojunction in CdTe.

  13. Synthesis, spectral (IR, UV-Vis and variable temperature NMR) characterization and crystal structure of (N-benzyl-N-furfuryldithicarbamato-S,S')(thiocyanato-N)(triphenylphosphine)nickel(II).

    PubMed

    Valarmathi, P; Thirumaran, S; Sarmal, Lovely; Kant, Rajni

    2014-08-14

    Planar (N-benzyl-N-furfuryldithiocarbamato-S,S')(thiocyanato-N)(triphenylphospine)nickel(II), [Ni(bfdtc)(NCS)(PPh3)], (1) was prepared from bis(N-benzyl-N-furfuryldithiocarbamato-S,S')nickel(II), [Ni(bfdtc)2], (2) and characterized by elemental analysis, cyclic voltammetry, electronic, IR and variable temperature (1)H and (13)C NMR spectra. For complex 1, the thioureide vCN value is shifted to higher wavenumber compared to 2 and N(13)CS2 carbon signal observed for 1 is additionally shielded compared to the parent complex 2, suggesting increased strength of the thioureide bond due to the presence of the π-accepting phosphine. In the room temperature (13)C NMR spectrum of 1, two pseudo doublets are observed in the aliphatic region. Variable temperature (13)C NMR spectral studies suggest that the fast thiocyanate exchange appears to be responsible for the appearance of pseudo doublets. Single crystal X-ray structural analysis of 1 and 2 confirm the presence of four coordinated nickel in a distorted square planar arrangement with the NiS2PN and NiS4 chromophores, respectively. The NiS bonds are symmetric in 2 (2.1914(14) and 2.2073(13)Å). But significant asymmetry in NiS bond distances was observed in 1 (2.2202(8)Å and 2.1841Å). This observation clearly supports the less effective trans effect of SCN(-) over PPh3. Cyclic voltammetric studies revealed easier reduction of nickel(II) to nickel(I) in complex 1 compared to 2.

  14. Choroidal neovascularization analyzed on ultra-high speed swept source optical coherence tomography angiography compared to spectral domain optical coherence tomography angiography

    PubMed Central

    Novais, Eduardo A.; Adhi, Mehreen; Moult, Eric M.; Louzada, Ricardo N.; Cole, Emily D.; Husvogt, Lennart; Lee, ByungKun; Dang, Sabin; Regatieri, Caio V. S.; Witkin, André J.; Baumal, Caroline R.; Hornegger, Joachim; Jayaraman, Vijaysekhar; Fujimoto, James G; Duker, Jay S.; Waheed, Nadia K.

    2016-01-01

    Purpose To compare visualization of choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD) using an ultra-high speed swept-source (SS)-optical coherence tomography angiography (OCTA) prototype versus a spectral-domain (SD)-OCTA device. Design Comparative analysis of diagnostic instruments. Methods Patients were prospectively recruited to be imaged on SD-OCT and SS-OCT devices on the same day. The SD-OCT device employed is the RTVue Avanti that operates at ~840nm wavelength and 70,000 A-scans/second. The SS-OCT device used is an ultra-high speed long-wavelength prototype that operates at ~1050nm wavelength and 400,000 A-scans/second. Two observers independently measured the CNV area on OCTA en face images from the two devices using ImageJ. The non-parametric Wilcoxon signed-rank test was used to compare area measurements and p-values of <0.05 were considered statistically significant. Results Fourteen eyes from 13 patients were enrolled. The CNV in 11 eyes (78.6%) were classified as type-1, 2 eyes (14.3%) as type-2, and 1 eye (7.1%) as mixed type. Total CNV area measured using SS-OCT and SD-OCT 3mm × 3mm OCTA were 0.949 ± 1.168mm2 and 0.340 ± 0.301mm2, respectively (p=0.001). For the 6mm × 6mm OCTA the total CNV area using SS-OCT and SD-OCT were 1.218 ± 1.284mm2 and 0.604 ± 0.597mm2, respectively (p=0.0019). The field of view did not significantly affect the measured CNV area (p=0.19 and p=0.18 for SS-OCT and SD-OCT respectively). Conclusion SS-OCTA yielded significantly larger CNV areas than SD-OCTA. It is possible that SS-OCTA is better able to demarcate the full extent of CNV vasculature. PMID:26851725

  15. Comparative modeling: the state of the art and protein drug target structure prediction.

    PubMed

    Liu, Tianyun; Tang, Grace W; Capriotti, Emidio

    2011-07-01

    The goal of computational protein structure prediction is to provide three-dimensional (3D) structures with resolution comparable to experimental results. Comparative modeling, which predicts the 3D structure of a protein based on its sequence similarity to homologous structures, is the most accurate computational method for structure prediction. In the last two decades, significant progress has been made on comparative modeling methods. Using the large number of protein structures deposited in the Protein Data Bank (~65,000), automatic prediction pipelines are generating a tremendous number of models (~1.9 million) for sequences whose structures have not been experimentally determined. Accurate models are suitable for a wide range of applications, such as prediction of protein binding sites, prediction of the effect of protein mutations, and structure-guided virtual screening. In particular, comparative modeling has enabled structure-based drug design against protein targets with unknown structures. In this review, we describe the theoretical basis of comparative modeling, the available automatic methods and databases, and the algorithms to evaluate the accuracy of predicted structures. Finally, we discuss relevant applications in the prediction of important drug target proteins, focusing on the G protein-coupled receptor (GPCR) and protein kinase families.

  16. Visualizing the Choriocapillaris Under Drusen: Comparing 1050-nm Swept-Source Versus 840-nm Spectral-Domain Optical Coherence Tomography Angiography

    PubMed Central

    Lane, Mark; Moult, Eric M.; Novais, Eduardo A.; Louzada, Ricardo N.; Cole, Emily D.; Lee, ByungKun; Husvogt, Lennart; Keane, Pearse A.; Denniston, Alastair K.; Witkin, André J.; Baumal, Caroline R.; Fujimoto, James G.; Duker, Jay S.; Waheed, Nadia K.

    2016-01-01

    Purpose To investigate the appearance of choriocapillaris (CC) flow under drusen by comparing long-wavelength (1050 nm) swept-source optical coherence tomography (SS-OCT) angiography with shorter-wavelength (840 nm) spectral-domain (SD) OCT angiography. Methods Patients with drusen imaged on both devices on the same day were selected and graded. Ambiguous OCT angiography (OCTA) signal loss was defined as low OCTA signal on the en face OCTA CC image that also had low OCT signal in the corresponding area on the en face OCT CC image and OCT B-scans. Unambiguous OCTA signal loss was defined as low OCTA signal on the en face OCTA CC image that did not have low OCT signal in the corresponding area on the en face OCT CC image and OCT B-scans. False-positive flow impairment on SS-OCTA was defined as ambiguous OCTA signal loss on SS-OCTA but no OCTA signal loss on SD-OCTA. False-positive flow impairment on SD-OCTA was defined as ambiguous OCTA signal loss on SD-OCTA but no OCTA signal loss on SS-OCTA. Results Nine eyes from seven patients were enrolled, 23 drusen were analyzed. On 840-nm SD-OCTA, 17 drusen (73.9%) exhibited OCTA signal loss. Fourteen (82.4%) were classified as ambiguous, and three (17.6%) were classified as unambiguous; 10 (58.8%) were classified as having false-positive flow impairment. On 1050-nm SS-OCTA, seven drusen (30.4%) exhibited OCTA signal loss and were classified as unambiguous; none were classified as having false-positive flow impairment. Conclusions Results showed that 1050-nm SS-OCTA appears less prone to producing areas of false-positive flow impairment under drusen. PMID:27547891

  17. Spectral fitting inversion of low-frequency normal modes with self-coupling and cross-coupling of toroidal and spheroidal multiplets: numerical experiments to estimate the isotropic and anisotropic velocity structures

    NASA Astrophysics Data System (ADS)

    Oda, Hitoshi

    2016-06-01

    The aspherical structure of the Earth is described in terms of lateral heterogeneity and anisotropy of the P- and S-wave velocities, density heterogeneity, ellipticity and rotation of the Earth and undulation of the discontinuity interfaces of the seismic wave velocities. Its structure significantly influences the normal mode spectra of the Earth's free oscillation in the form of cross-coupling between toroidal and spheroidal multiplets and self-coupling between the singlets forming them. Thus, the aspherical structure must be conversely estimated from the free oscillation spectra influenced by the cross-coupling and self-coupling. In the present study, we improve a spectral fitting inversion algorithm which was developed in a previous study to retrieve the global structures of the isotropic and anisotropic velocities of the P and S waves from the free oscillation spectra. The main improvement is that the geographical distribution of the intensity of the S-wave azimuthal anisotropy is represented by a nonlinear combination of structure coefficients for the anisotropic velocity structure, whereas in the previous study it was expanded into a generalized spherical harmonic series. Consequently, the improved inversion algorithm reduces the number of unknown parameters that must be determined compared to the previous inversion algorithm and employs a one-step inversion method by which the structure coefficients for the isotropic and anisotropic velocities are directly estimated from the fee oscillation spectra. The applicability of the improved inversion is examined by several numerical experiments using synthetic spectral data, which are produced by supposing a variety of isotropic and anisotropic velocity structures, earthquake source parameters and station-event pairs. Furthermore, the robustness of the inversion algorithm is investigated with respect to the back-ground noise contaminating the spectral data as well as truncating the series expansions by finite terms

  18. Spectral phasor analysis of LAURDAN fluorescence in live A549 lung cells to study the hydration and time evolution of intracellular lamellar body-like structures.

    PubMed

    Malacrida, Leonel; Astrada, Soledad; Briva, Arturo; Bollati-Fogolín, Mariela; Gratton, Enrico; Bagatolli, Luis A

    2016-11-01

    Using LAURDAN spectral imaging and spectral phasor analysis we concurrently studied the growth and hydration state of subcellular organelles (lamellar body-like, LB-like) from live A549 lung cancer cells at different post-confluence days. Our results reveal a time dependent two-step process governing the size and hydration of these intracellular LB-like structures. Specifically, a first step (days 1 to 7) is characterized by an increase in their size, followed by a second one (days 7 to 14) where the organelles display a decrease in their global hydration properties. Interestingly, our results also show that their hydration properties significantly differ from those observed in well-characterized artificial lamellar model membranes, challenging the notion that a pure lamellar membrane organization is present in these organelles at intracellular conditions. Finally, these LB-like structures show a significant increase in their hydration state upon secretion, suggesting a relevant role of entropy during this process.

  19. Preparation and Absorption Spectral Property of a Multifunctional Water-Soluble Azo Compound with D-π-A Structure, 4-(4- Hydroxy-1-Naphthylazo)Benzoic Acid

    NASA Astrophysics Data System (ADS)

    Hu, L.; Lv, H.; Xie, C. G.; Chang, W. G.; Yan, Z. Q.

    2015-07-01

    A multifunctional water-soluble azo dye with the D-π-A conjugated structure, 4-(4-hydroxy-1-naphthylazo) benzoic acid ( HNBA), was designed and synthesized using 1-naphanol as the electron donator, benzoic acid as the electron acceptor, and -N=N- as the bridging group. After its structure was characterized by FTIR, 1H NMR, and element analysis, the UV-Vis absorption spectral performance of the target dye was studied in detail. The results showed that the dye, combining hydroxyl group, azo group, and carboxyl group, possessed excellent absorption spectral properties (ɛ = 1.2·104 l·mol-1·cm-1) changing with pH and solvents. In particular, in polar and protonic water, it had excellent optical response to some metal ions, i.e., Fe3+ and Pb2+, which might make it a latent colorimetric sensor for detecting heavy metal ions.

  20. A structural, magnetic, and Mössbauer spectral study of several Na Mn Fe-bearing alluaudites

    NASA Astrophysics Data System (ADS)

    Hatert, F.; Long, G. J.; Hautot, D.; Fransolet, A.-M.; Delwiche, J.; Hubin-Franskin, M. J.; Grandjean, F.

    2004-10-01

    The synthesis and the chemical, structural, magnetic, and Mössbauer spectral characterization of three synthetic alluaudites, Na2Mn2Fe(PO4)3, NaMn Fe2(PO4)3 and Na2MnFeIIFeIII(PO4)3, and a natural sample with the nominal composition of NaMn Fe2(PO4)3, collected in the Buranga pegmatite, Rwanda, are reported. All four compounds have the expected alluaudite monoclinic C2/c structure with the general formula [A(2)A(2)’][A(1)A(1)’A(1)2”]M(1)M(2)2(PO4)3 in which manganese(II) is on the M(1) site and manganese(II), iron(III) and, in some cases, iron(II) on the M(2) site. The X-ray structure of Na2Mn2Fe(PO4)3 also indicates a partially disordered distribution of NaI and MnII on the M(1) and A(1) crystallographic sites. All four compounds are paramagnetic above 40 K and antiferromagnetically ordered below. Above 40 K the effective magnetic moments of NaMnFe2(PO4)3 and Na2MnFeIIFeIII(PO4)3 are those expected of high-spin manganese(II) and iron(III) with the 6A1g electronic ground state and high-spin iron(II) with the 5T2g electronic ground state. In contrast, the effective magnetic moment of Na2Mn2Fe(PO4)3 is lower than expected as a result of enhanced antiferromagnetic exchange coupling by the manganese(II) on the M(2) site. The Mössbauer spectra of all four compounds have been measured from 4.2 to 295 K and have been found to be magnetically ordered below 40 K for Na2Mn2Fe(PO4)3 and ˜35 K for the remaining compounds. The Mössbauer spectra of Na2Mn2Fe(PO4)3 exhibit the two expected iron(III) quadrupole doublets and/or magnetic sextets expected for a random distribution of manganese(II) and iron(III) ions on the M(2) site. Further, the Mössbauer spectra of Na2MnFeIIFeIII(PO4)3 exhibit the two iron(II) and two iron(III) quadrupole doublets and/or magnetic sextets expected for a random distribution of iron(II) and iron(III) on the M(2) site. Surprisingly, the synthetic and natural samples of NaMnFe2(PO4)3 have 19 and 10% of iron(II) on the M(2) site; apparently the

  1. Macro- and microscopic spectral-polarization characteristics of the structure of normal and abnormally located chordae tendianeae of left ventricular

    NASA Astrophysics Data System (ADS)

    Malyk, Yu. Yu.; Prydij, O. G.; Zymnyakov, D. A.; Alonova, M. V.; Ushakova, O. V.

    2013-12-01

    The morphological peculiarities of TS mitral valve of the heart of man in normal and abnormal spaced strings of the left ventricle and the study of their structural features depending on the location was studied. There are given the results of comparative statistics, correlation and fractal study population Mueller-matrix images (MMI) of healthy and abnormal (early forms that are not diagnosed by histological methods) BT normal and abnormally located tendon strings left ventricle of the human heart. Abnormalities in the structure of the wings, tendon strings (TS), mastoid muscle (MM) in inconsistencies elements and harmonized operation of all valve complex shown in the features of the polarization manifestations of it laser images.

  2. Evaluation of Various Spectral Inputs for Estimation of Forest Biochemical and Structural Properties from Airborne Imaging Spectroscopy Data

    NASA Astrophysics Data System (ADS)

    Homolová, L.; Janoutová, R.; Malenovský, Z.

    2016-06-01

    In this study we evaluated various spectral inputs for retrieval of forest chlorophyll content (Cab) and leaf area index (LAI) from high spectral and spatial resolution airborne imaging spectroscopy data collected for two forest study sites in the Czech Republic (beech forest at Štítná nad Vláří and spruce forest at Bílý Kříž). The retrieval algorithm was based on a machine learning method - support vector regression (SVR). Performance of the four spectral inputs used to train SVR was evaluated: a) all available hyperspectral bands, b) continuum removal (CR) 645 - 710 nm, c) CR 705 - 780 nm, and d) CR 680 - 800 nm. Spectral inputs and corresponding SVR models were first assessed at the level of spectral databases simulated by combined leaf-canopy radiative transfer models PROSPECT and DART. At this stage, SVR models using all spectral inputs provided good performance (RMSE for Cab < 10 μg cm-2 and for LAI < 1.5), with consistently better performance for beech over spruce site. Since application of trained SVRs on airborne hyperspectral images of the spruce site produced unacceptably overestimated values, only the beech site results were analysed. The best performance for the Cab estimation was found for CR bands in range of 645 - 710 nm, whereas CR bands in range of 680 - 800 nm were the most suitable for LAI retrieval. The CR transformation reduced the across-track bidirectional reflectance effect present in airborne images due to large sensor field of view.

  3. Molecular structure, vibrational spectral studies of pyrazole and 3,5-dimethyl pyrazole based on density functional calculations.

    PubMed

    Krishnakumar, V; Jayamani, N; Mathammal, R

    2011-09-01

    In this work, the experimental and theoretical vibrational spectra of pyrazole (PZ) and 3,5-dimethyl pyrazole (DMP) have been studied. FTIR and FT-Raman spectra of the title compounds in the solid phase are recorded in the region 4000-400 cm(-1) and 4000-50 cm(-1), respectively. The structural and spectroscopic data of the molecules in the ground state are calculated using density functional methods (B3LYP) with 6-311+G** basis set. The vibrational frequencies are calculated and scaled values are compared with experimental FTIR and FT-Raman spectra. The observed and calculated frequencies are found to be in good agreement. The complete vibrational assignments are performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanical (SM) method. 13C and 1H NMR chemical shifts results are compared with the experimental values.

  4. Protein Dynamics from NMR: The Slowly Relaxing Local Structure Analysis Compared with Model-Free Analysis

    PubMed Central

    Meirovitch, Eva; Shapiro, Yury E.; Polimeno, Antonino; Freed, Jack H.

    2009-01-01

    15N-1H spin relaxation is a powerful method for deriving information on protein dynamics. The traditional method of data analysis is model-free (MF), where the global and local N-H motions are independent and the local geometry is simplified. The common MF analysis consists of fitting single-field data. The results are typically field-dependent, and multi-field data cannot be fit with standard fitting schemes. Cases where known functional dynamics has not been detected by MF were identified by us and others. Recently we applied to spin relaxation in proteins the Slowly Relaxing Local Structure (SRLS) approach which accounts rigorously for mode-mixing and general features of local geometry. SRLS was shown to yield MF in appropriate asymptotic limits. We found that the experimental spectral density corresponds quite well to the SRLS spectral density. The MF formulae are often used outside of their validity ranges, allowing small data sets to be force-fitted with good statistics but inaccurate best-fit parameters. This paper focuses on the mechanism of force-fitting and its implications. It is shown that MF force-fits the experimental data because mode-mixing, the rhombic symmetry of the local ordering and general features of local geometry are not accounted for. Combined multi-field multi-temperature data analyzed by MF may lead to the detection of incorrect phenomena, while conformational entropy derived from MF order parameters may be highly inaccurate. On the other hand, fitting to more appropriate models can yield consistent physically insightful information. This requires that the complexity of the theoretical spectral densities matches the integrity of the experimental data. As shown herein, the SRLS densities comply with this requirement. PMID:16821820

  5. Sublimation of Ices Containing Organics and/or Minerals and Implications for Icy Bodies Surface Structure and Spectral Properties

    NASA Astrophysics Data System (ADS)

    Poch, O.; Pommerol, A.; Jost, B.; Yoldi, Z.; Carrasco, N.; Szopa, C.; Thomas, N.

    2015-12-01

    The surfaces of many objects in the Solar System comprise substantial quantities of water ice either in pure form or mixed with minerals and/or organic molecules. Sublimation is a process responsible for shaping and changing the reflectance properties of these objects. We present laboratory data on the evolution of the structure and the visible and near-infrared spectral reflectance of icy surfaces made of mixtures of water ice and non-volatile components (complex organic matter and silicates), as they undergo sublimation of the water ice under low temperature and pressure conditions (Poch et al., under review). We prepared icy surfaces which are potential analogues of ices found on comets, icy satellites or trans-neptunian objects (TNOs). The experiments were carried out in the SCITEAS simulation setup recently built as part of the Laboratory for Outflow Studies of Sublimating Materials (LOSSy) at the University of Bern (Pommerol et al., 2015a). As the water ice sublimated, we observed in situ the formation of a sublimation lag deposit, or sublimation mantle, made of the non-volatiles at the top of the samples. The texture (porosity, internal cohesiveness etc.), the activity (outbursts and ejection of mantle fragments) and the spectro-photometric properties of this mantle are found to differ strongly depending on the chemical nature of the non-volatiles, the size of their particles, the way they are mixed with the volatile component and the dust/ice mass ratio. The results also indicate how the band depths of the sub-surface water ice evolve during the build-up of the sublimation mantle. These data provide useful references for interpreting remote-sensing observations of Rosetta (see Pommerol et al., 2015b), and also New Horizons. Poch, O., et al., under review in IcarusPommerol, A., et al., 2015a, Planet. Space Sci. 109-110, 106-122. http://dx.doi.org/10.1016/j.pss.2015.02.004Pommerol, A., et al., 2015b, Astronomy and Astrophysics, in press. http://dx.doi.org/10.1051/0004-6361/201525977

  6. Effect of Bioaccumulation of Cs and Sr Natural Isotopes on Foliar Structure and Plant Spectral Reflectance of Indian Mustard (Brassica juncea)

    SciTech Connect

    Maruthi Sridhar, Y.S.B.B.; Han, F.X.; Monts, D.L.; Diehl, S.V.

    2008-07-01

    The objectives of this study are: 1.) evaluate the capacity of Indian mustard (Brassica juncea) for uptake and accumulation of Cs and Sr natural isotopes; 2.) identify foliar structural and other physiological changes (biomass, relative water content, etc.) resulting from the accumulation of these two elements; and 3.) monitor Cs and Sr uptake and bioaccumulation process by spectral reflectance. Potted Indian mustard plants were exposed to different concentrations of Cs (50 and 600 ppm) and Sr (50 and 300 ppm) natural isotopes in solution form for 23 days. Bioaccumulation of Cs and Sr was found in the order of leaves > stems > roots for both Cs- and Sr-treated plants. The highest leaf Sr accumulation is observed to be 2708 mg kg{sup -1}, and the highest leaf Cs accumulation is 12251 mg kg{sup -1}. High translocation efficiency for both elements is documented by shoot/root concentration ratios greater than one. Relative water content (RWC) of the plants showed a significant (p < 0.05) decrease in Cs-treated plants. Cs accumulation also affected the pigment concentration and internal structure of the leaf and the spectral characteristics of plants. Within the applied concentration range, Sr accumulation resulted in no significant changes in RWC, structural and spectral characteristics of mustard plants. Cs shoot concentration showed significant negative correlation with relative water content RWC (r = -0.88) and Normalized Difference Vegetation Index (NDVI) (r = -0.68) of plant shoots. The canopy spectral reflectance and NDVI analysis clearly revealed (p < 0.05) the stress caused by Cs accumulation. (authors)

  7. Infrared, vibrational circular dichroism, and Raman spectral simulations for β-sheet structures with various isotopic labels, interstrand, and stacking arrangements using density functional theory.

    PubMed

    Welch, William R W; Kubelka, Jan; Keiderling, Timothy A

    2013-09-12

    Infrared (IR), Raman, and vibrational circular dichroism (VCD) spectral variations for different β-sheet structures were studied using simulations based on density functional theory (DFT) force field and intensity computations. The DFT vibrational parameters were obtained for β-sheet fragments containing nine-amides and constrained to a variety of conformations and strand arrangements. These were subsequently transferred onto corresponding larger β-sheet models, normally consisting of five strands with ten amides each, for spectral simulations. Further extension to fibril models composed of multiple stacked β-sheets was achieved by combining the transfer of DFT parameters for each sheet with dipole coupling methods for interactions between sheets. IR spectra of the amide I show different splitting patterns for parallel and antiparallel β-sheets, and their VCD, in the absence of intersheet stacking, have distinct sign variations. Isotopic labeling by (13)C of selected residues yields spectral shifts and intensity changes uniquely sensitive to relative alignment of strands (registry) for antiparallel sheets. Stacking of multiple planar sheets maintains the qualitative spectral character of the single sheet but evidences some reduction in the exciton splitting of the amide I mode. Rotating sheets with respect to each other leads to a significant VCD enhancement, whose sign pattern and intensity is dependent on the handedness and degree of rotation. For twisted β-sheets, a significant VCD enhancement is computed even for sheets stacked with either the same or opposite alignments and the inter-sheet rotation, depending on the sense, can either further increase or weaken the enhanced VCD intensity. In twisted, stacked structures (without rotation), similar VCD amide I patterns (positive couplets) are predicted for both parallel and antiparallel sheets, but different IR intensity distributions still enable their differentiation. Our simulation results prove useful

  8. Toward a Model of Knowledge Structure and a Comparative Analysis of Knowledge Structure Measurement Techniques

    DTIC Science & Technology

    1991-09-01

    POLYCON, INDSCAL/SINDSCAL, KYST, and MULTISCALE). Polzella and Reid (1989) employed MDS techniques to discover differences in performance characteristics...Reasoning and the structure of knowledge in biochemistry. Instructional Science, 17, 57-76. Polzella , D. J., and Reid, G. B. (1989

  9. Temporal Lorentzian spectral triples

    NASA Astrophysics Data System (ADS)

    Franco, Nicolas

    2014-09-01

    We present the notion of temporal Lorentzian spectral triple which is an extension of the notion of pseudo-Riemannian spectral triple with a way to ensure that the signature of the metric is Lorentzian. A temporal Lorentzian spectral triple corresponds to a specific 3 + 1 decomposition of a possibly noncommutative Lorentzian space. This structure introduces a notion of global time in noncommutative geometry. As an example, we construct a temporal Lorentzian spectral triple over a Moyal-Minkowski spacetime. We show that, when time is commutative, the algebra can be extended to unbounded elements. Using such an extension, it is possible to define a Lorentzian distance formula between pure states with a well-defined noncommutative formulation.

  10. Advanced spectral signature discrimination algorithm

    NASA Astrophysics Data System (ADS)

    Chakravarty, Sumit; Cao, Wenjie; Samat, Alim

    2013-05-01

    This paper presents a novel approach to the task of hyperspectral signature analysis. Hyperspectral signature analysis has been studied a lot in literature and there has been a lot of different algorithms developed which endeavors to discriminate between hyperspectral signatures. There are many approaches for performing the task of hyperspectral signature analysis. Binary coding approaches like SPAM and SFBC use basic statistical thresholding operations to binarize a signature which are then compared using Hamming distance. This framework has been extended to techniques like SDFC wherein a set of primate structures are used to characterize local variations in a signature together with the overall statistical measures like mean. As we see such structures harness only local variations and do not exploit any covariation of spectrally distinct parts of the signature. The approach of this research is to harvest such information by the use of a technique similar to circular convolution. In the approach we consider the signature as cyclic by appending the two ends of it. We then create two copies of the spectral signature. These three signatures can be placed next to each other like the rotating discs of a combination lock. We then find local structures at different circular shifts between the three cyclic spectral signatures. Texture features like in SDFC can be used to study the local structural variation for each circular shift. We can then create different measure by creating histogram from the shifts and thereafter using different techniques for information extraction from the histograms. Depending on the technique used different variant of the proposed algorithm are obtained. Experiments using the proposed technique show the viability of the proposed methods and their performances as compared to current binary signature coding techniques.

  11. A Comparative Structural Equation Modeling Investigation of the Relationships among Teaching, Cognitive and Social Presence

    ERIC Educational Resources Information Center

    Kozan, Kadir

    2016-01-01

    The present study investigated the relationships among teaching, cognitive, and social presence through several structural equation models to see which model would better fit the data. To this end, the present study employed and compared several different structural equation models because different models could fit the data equally well. Among…

  12. Biosimilar structural comparability assessment by NMR: from small proteins to monoclonal antibodies

    PubMed Central

    Japelj, Boštjan; Ilc, Gregor; Marušič, Jaka; Senčar, Jure; Kuzman, Drago; Plavec, Janez

    2016-01-01

    Biosimilar drug products must have a demonstrated similarity with respect to the reference product’s molecules in order to ensure both the effectiveness of the drug and the patients’ safety. In this paper the fusion framework of a highly sensitive NMR fingerprinting approach for conformational changes and mathematically-based biosimilarity metrics is introduced. The final goal is to translate the complex spectral information into biosimilarity scores, which are then used to estimate the degree of similarity between the biosimilar and the reference product. The proposed method was successfully applied to a small protein, i.e., filgrastim (neutropenia treatment), which is the first biosimilar approved in the United States, and a relatively large protein, i.e., monoclonal antibody rituximab (lymphoma treatment). This innovative approach introduces a new level of sensitivity to structural changes that are induced by, e.g., a small pH shift or other changes in the protein formulation. PMID:27578487

  13. Biosimilar structural comparability assessment by NMR: from small proteins to monoclonal antibodies

    NASA Astrophysics Data System (ADS)

    Japelj, Boštjan; Ilc, Gregor; Marušič, Jaka; Senčar, Jure; Kuzman, Drago; Plavec, Janez

    2016-08-01

    Biosimilar drug products must have a demonstrated similarity with respect to the reference product’s molecules in order to ensure both the effectiveness of the drug and the patients’ safety. In this paper the fusion framework of a highly sensitive NMR fingerprinting approach for conformational changes and mathematically-based biosimilarity metrics is introduced. The final goal is to translate the complex spectral information into biosimilarity scores, which are then used to estimate the degree of similarity between the biosimilar and the reference product. The proposed method was successfully applied to a small protein, i.e., filgrastim (neutropenia treatment), which is the first biosimilar approved in the United States, and a relatively large protein, i.e., monoclonal antibody rituximab (lymphoma treatment). This innovative approach introduces a new level of sensitivity to structural changes that are induced by, e.g., a small pH shift or other changes in the protein formulation.

  14. Adaptive spectral doppler estimation.

    PubMed

    Gran, Fredrik; Jakobsson, Andreas; Jensen, Jørgen Arendt

    2009-04-01

    In this paper, 2 adaptive spectral estimation techniques are analyzed for spectral Doppler ultrasound. The purpose is to minimize the observation window needed to estimate the spectrogram to provide a better temporal resolution and gain more flexibility when designing the data acquisition sequence. The methods can also provide better quality of the estimated power spectral density (PSD) of the blood signal. Adaptive spectral estimation techniques are known to provide good spectral resolution and contrast even when the observation window is very short. The 2 adaptive techniques are tested and compared with the averaged periodogram (Welch's method). The blood power spectral capon (BPC) method is based on a standard minimum variance technique adapted to account for both averaging over slow-time and depth. The blood amplitude and phase estimation technique (BAPES) is based on finding a set of matched filters (one for each velocity component of interest) and filtering the blood process over slow-time and averaging over depth to find the PSD. The methods are tested using various experiments and simulations. First, controlled flow-rig experiments with steady laminar flow are carried out. Simulations in Field II for pulsating flow resembling the femoral artery are also analyzed. The simulations are followed by in vivo measurement on the common carotid artery. In all simulations and experiments it was concluded that the adaptive methods display superior performance for short observation windows compared with the averaged periodogram. Computational costs and implementation details are also discussed.

  15. Azide derivatized anticancer agents of Vitamin K 3: X-ray structural, DSC, resonance spectral and API studies

    NASA Astrophysics Data System (ADS)

    Badave, Kirti; Patil, Yogesh; Gonnade, Rajesh; Srinivas, Darbha; Dasgupta, Rajan; Khan, Ayesha; Rane, Sandhya

    2011-12-01

    Compound 1 [1-imino (acetyl hydrazino)-Vitamin K 3], displays valence tautomerically related electronic isomers as Form I and Form II. Form I exhibits 2D packing fragment with 1D ribbon chains of N-H⋯O hydrogen bonds and shows EPR silent features. While Form II is EPR active and exhibits biradical nature with double quantum transitions at g = 2.0040. 1H NMR of compound 2, [1-imino (hydrazino carboxylate)-Vitamin K 3] and Form II exhibit π delocalization via resonance assisted H-bonding [RAHB] effect compared to Form I. Molecular interactions in Form I and II are visualized by DSC. The electronic structures of compounds 1 and 2 have been correlated to their API values by measuring anticancer activities, mitochondrial potentials and DNA shearing patterns. Form II and compound 2 indicate mitochondria mediated apoptosis (˜75% cell death) while Form I causes 35% cell death.

  16. Selective coordination ability of sulfamethazine Schiff-base ligand towards copper(II): molecular structures, spectral and SAR study.

    PubMed

    Mansour, Ahmed M

    2014-04-05

    In the present work, a combined experimental and theoretical study of the N-(4,6-Dimethyl-pyrimidin-2-yl)-4-[(2-hydroxy-benzylidene)amino]benzenesulfonamide ligand (H2L) and its mononuclear and magnetically diluted binuclear Cu(II) complexes has been performed using IR, TG/DTA, magnetic, EPR, and conductivity measurements. Calculated g-tensor values showed best agreement with experimental values from EPR when carried out using the MPW1PW91 functional. Coordination of H2L to a Cu(II) center, regardless of the binding site and Cu:L stoichiometry, leads to a significant decrease in the antibacterial activity compared to the free ligand as well as reference drugs in the case of Staphylococcus aureus. Structural-activity relationship suggests that ELUMO, ΔE, dipole moment, polarizability and electrophilicity index were the most significant descriptors for the correlation with the antibacterial activity.

  17. Monte Carlo modelling of photodynamic therapy treatments comparing clustered three dimensional tumour structures with homogeneous tissue structures

    NASA Astrophysics Data System (ADS)

    Campbell, C. L.; Wood, K.; Brown, C. T. A.; Moseley, H.

    2016-07-01

    We explore the effects of three dimensional (3D) tumour structures on depth dependent fluence rates, photodynamic doses (PDD) and fluorescence images through Monte Carlo radiation transfer modelling of photodynamic therapy. The aim with this work was to compare the commonly used uniform tumour densities with non-uniform densities to determine the importance of including 3D models in theoretical investigations. It was found that fractal 3D models resulted in deeper penetration on average of therapeutic radiation and higher PDD. An increase in effective treatment depth of 1 mm was observed for one of the investigated fractal structures, when comparing to the equivalent smooth model. Wide field fluorescence images were simulated, revealing information about the relationship between tumour structure and the appearance of the fluorescence intensity. Our models indicate that the 3D tumour structure strongly affects the spatial distribution of therapeutic light, the PDD and the wide field appearance of surface fluorescence images.

  18. A COMPARATIVE STUDY ON SPECTRAL ENERGETICS BETWEEN THE NCEP reanalysisII in current climate AND MODEL ECHAM5 in future scenarios

    NASA Astrophysics Data System (ADS)

    Aranha, A. F.; Veiga, J. P.

    2013-12-01

    Saltzman (1957) starting Lorenz Cycle (1955) derived a set of equations that show the energy contained in the basic state and the disturbed atmosphere, decomposing in various fields disturbance wave type, so as to quantify and analyze the energy of these disorders according to their number or wavelength. Based on the methodology Saltzman, this paper aims a comparative study between the energy of the disturbed state between the NCEP reanalysis-II for the current weather conditions and model ECHAM5 scenarios for future conditions of increased concentration of greenhouse gases (RCP26, RCP45 and RCP85), considering the terms of the generation of available potential energy to nth wave due to diabatic heating, represented by (Gn), the potential energy of nth wave (Pn) and kinetic energy of nth wave (Kn), as well as the conversion of energy between kinetic energy and potential energy nth wave of nth wave, given by (Cn). Two data sets were used in the calculation of the aforementioned terms. For the data set of NCEP and ECHAM5 were used variables, temperature (T), orthogonal wind components (u, v, w) and geopotential height (L), considering daily shared values on a regular grid with spatial resolutions of 2,5 x 2.5 and 1.875 x 1.875 graus, distributed on 12 and 15 levels of pressure (1000.0, 925.0, 850.0, 700.0, 600.0, 500.0, 400.0, 300.0, 250.0, 200.0, 150.0, 100.0 hPa), (1000.0, 850.0, 700.0, 500.0, 250.0, 150.0, 100.0, 70.0, 50.0, 30.0, 10.0, 3.0, 1.0, 0.3, 0.1 hPa) for the period of 1979-1999 and 2090-2100, respectively. The results show that most of the kinetic energy of disturbance to nth waves is concentrated in the first 15 wave numbers, both for the weather-NCEP II as to ECHAM5, having more significant increase in the profile and having a RCP85 energy cascade. This increase in kinetic energy was expected due to the increased energy in the system. For Pn, increasing the potential energy is also expected in view of the increased diabatic heating, but the energy jump

  19. A comparative study of theoretical graph models for characterizing structural networks of human brain.

    PubMed

    Li, Xiaojin; Hu, Xintao; Jin, Changfeng; Han, Junwei; Liu, Tianming; Guo, Lei; Hao, Wei; Li, Lingjiang

    2013-01-01

    Previous studies have investigated both structural and functional brain networks via graph-theoretical methods. However, there is an important issue that has not been adequately discussed before: what is the optimal theoretical graph model for describing the structural networks of human brain? In this paper, we perform a comparative study to address this problem. Firstly, large-scale cortical regions of interest (ROIs) are localized by recently developed and validated brain reference system named Dense Individualized Common Connectivity-based Cortical Landmarks (DICCCOL) to address the limitations in the identification of the brain network ROIs in previous studies. Then, we construct structural brain networks based on diffusion tensor imaging (DTI) data. Afterwards, the global and local graph properties of the constructed structural brain networks are measured using the state-of-the-art graph analysis algorithms and tools and are further compared with seven popular theoretical graph models. In addition, we compare the topological properties between two graph models, namely, stickiness-index-based model (STICKY) and scale-free gene duplication model (SF-GD), that have higher similarity with the real structural brain networks in terms of global and local graph properties. Our experimental results suggest that among the seven theoretical graph models compared in this study, STICKY and SF-GD models have better performances in characterizing the structural human brain network.

  20. THE INFLUENCE OF THE EXTREME ULTRAVIOLET SPECTRAL ENERGY DISTRIBUTION ON THE STRUCTURE AND COMPOSITION OF THE UPPER ATMOSPHERE OF EXOPLANETS

    SciTech Connect

    Guo, J. H.; Ben-Jaffel, Lotfi E-mail: bjaffel@iap.fr

    2016-02-20

    By varying the profiles of stellar extreme ultraviolet (EUV) spectral energy distributions (SEDs), we tested the influences of stellar EUV SEDs on the physical and chemical properties of an escaping atmosphere. We apply our model to study four exoplanets: HD 189733b, HD 209458b, GJ 436b, and Kepler-11b. We find that the total mass loss rates of an exoplanet, which are determined mainly by the integrated fluxes, are moderately affected by the profiles of the EUV SED, but the composition and species distributions in the atmosphere can be dramatically modified by the different profiles of the EUV SED. For exoplanets with a high hydrodynamic escape parameter (λ), the amount of atomic hydrogen produced by photoionization at different altitudes can vary by one to two orders of magnitude with the variation of stellar EUV SEDs. The effect of photoionization of H is prominent when the EUV SED is dominated by the low-energy spectral region (400–900 Å), which pushes the transition of H/H{sup +} to low altitudes. In contrast, the transition of H/H{sup +} moves to higher altitudes when most photons are concentrated in the high-energy spectral region (50–400 Å). For exoplanets with a low λ, the lower temperatures of the atmosphere make many chemical reactions so important that photoionization alone can no longer determine the composition of the escaping atmosphere. For HD 189733b, it is possible to explain the time variability of Lyα between 2010 and 2011 by a change in the EUV SED of the host K-type star, yet invoking only thermal H i in the atmosphere.

  1. Comparative study between a spectral domain and a high-speed single-beam swept source OCTA system for identifying choroidal neovascularization in AMD

    NASA Astrophysics Data System (ADS)

    Told, R.; Ginner, L.; Hecht, A.; Sacu, S.; Leitgeb, R.; Pollreisz, A.; Schmidt-Erfurth, U.

    2016-12-01

    This comparative study between a SD- and SS-OCTA system for visualizing neovascular patterns in AMD, also assessed the influence of cataract on OCTA imaging. 25 eyes with active CNV (AMD) were documented by FA, ICGA and SD-OCT. Two OCTA devices were used: A custom built SS-OCTA (1050 nm, 400,000 A-scans/s, 5 × 5 mm, no image segmentation); AngioVue (OptoVue, CA, USA) SD-OCTA (840 nm, 70.000 A-scans/s, 3 × 3 mm, SSADA technology). Two retina experts graded CNV types and vascular patterns. Cataract influence on OCTA image quality was reported for the superficial retinal plexus (6 eyes). The SS-OCTA prototype showed more CNV lesions compared to the SD-OCTA system (p = 0.01). Overall sensitivity of SD- and SS-OCTA systems to detect CNV lesions was.32 and.68, respectively. The SS-OCTA system was able to detect discrete lesion characteristics better than the SD-OCTA. No significant difference was found in the ability to identify CNV in treatment-naïve eyes. There was no significant influence of cataract. The SS-OCTA prototype detected CNV-associated vascular patterns more reliably than the SD-OCTA system. This is attributed to the SS-OCTA system’s longer center wavelength and higher A-scan rate yielding higher definition and contrast of small neovascular structures. The SS-OCTA system used showed no advantage regarding cataract influence.

  2. Comparative study between a spectral domain and a high-speed single-beam swept source OCTA system for identifying choroidal neovascularization in AMD.

    PubMed

    Told, R; Ginner, L; Hecht, A; Sacu, S; Leitgeb, R; Pollreisz, A; Schmidt-Erfurth, U

    2016-12-05

    This comparative study between a SD- and SS-OCTA system for visualizing neovascular patterns in AMD, also assessed the influence of cataract on OCTA imaging. 25 eyes with active CNV (AMD) were documented by FA, ICGA and SD-OCT. Two OCTA devices were used: A custom built SS-OCTA (1050 nm, 400,000 A-scans/s, 5 × 5 mm, no image segmentation); AngioVue (OptoVue, CA, USA) SD-OCTA (840 nm, 70.000 A-scans/s, 3 × 3 mm, SSADA technology). Two retina experts graded CNV types and vascular patterns. Cataract influence on OCTA image quality was reported for the superficial retinal plexus (6 eyes). The SS-OCTA prototype showed more CNV lesions compared to the SD-OCTA system (p = 0.01). Overall sensitivity of SD- and SS-OCTA systems to detect CNV lesions was.32 and.68, respectively. The SS-OCTA system was able to detect discrete lesion characteristics better than the SD-OCTA. No significant difference was found in the ability to identify CNV in treatment-naïve eyes. There was no significant influence of cataract. The SS-OCTA prototype detected CNV-associated vascular patterns more reliably than the SD-OCTA system. This is attributed to the SS-OCTA system's longer center wavelength and higher A-scan rate yielding higher definition and contrast of small neovascular structures. The SS-OCTA system used showed no advantage regarding cataract influence.

  3. Comparative study between a spectral domain and a high-speed single-beam swept source OCTA system for identifying choroidal neovascularization in AMD

    PubMed Central

    Told, R.; Ginner, L.; Hecht, A.; Sacu, S.; Leitgeb, R.; Pollreisz, A.; Schmidt-Erfurth, U.

    2016-01-01

    This comparative study between a SD- and SS-OCTA system for visualizing neovascular patterns in AMD, also assessed the influence of cataract on OCTA imaging. 25 eyes with active CNV (AMD) were documented by FA, ICGA and SD-OCT. Two OCTA devices were used: A custom built SS-OCTA (1050 nm, 400,000 A-scans/s, 5 × 5 mm, no image segmentation); AngioVue (OptoVue, CA, USA) SD-OCTA (840 nm, 70.000 A-scans/s, 3 × 3 mm, SSADA technology). Two retina experts graded CNV types and vascular patterns. Cataract influence on OCTA image quality was reported for the superficial retinal plexus (6 eyes). The SS-OCTA prototype showed more CNV lesions compared to the SD-OCTA system (p = 0.01). Overall sensitivity of SD- and SS-OCTA systems to detect CNV lesions was.32 and.68, respectively. The SS-OCTA system was able to detect discrete lesion characteristics better than the SD-OCTA. No significant difference was found in the ability to identify CNV in treatment-naïve eyes. There was no significant influence of cataract. The SS-OCTA prototype detected CNV-associated vascular patterns more reliably than the SD-OCTA system. This is attributed to the SS-OCTA system’s longer center wavelength and higher A-scan rate yielding higher definition and contrast of small neovascular structures. The SS-OCTA system used showed no advantage regarding cataract influence. PMID:27917889

  4. Structural and spectral studies of Yb:NaGd(WO4)2 crystals irradiated by 6.0 MeV O ions

    NASA Astrophysics Data System (ADS)

    Jia, Chuan-Lei; Li, Song; Song, Xiao-Xiao

    2017-03-01

    Yb:NaGd(WO4)2 single crystals are implanted with 6.0 MeV O ions at room temperature. The effects of ion irradiation on the structure and spectral properties are demonstrated by employing X-ray diffraction techniques, high resolution X-ray diffraction techniques and photoluminescence (PL) measurement. The corresponding results show that the sample can retain good crystallinity by irradiation at relative low fluences of 1.6 × 1014 ions/cm2, whilst both the PL intensity and the line bandwidth can be effectively improved.

  5. Automated spectral classification and the GAIA project

    NASA Technical Reports Server (NTRS)

    Lasala, Jerry; Kurtz, Michael J.

    1995-01-01

    Two dimensional spectral types for each of the stars observed in the global astrometric interferometer for astrophysics (GAIA) mission would provide additional information for the galactic structure and stellar evolution studies, as well as helping in the identification of unusual objects and populations. The classification of the large quantity generated spectra requires that automated techniques are implemented. Approaches for the automatic classification are reviewed, and a metric-distance method is discussed. In tests, the metric-distance method produced spectral types with mean errors comparable to those of human classifiers working at similar resolution. Data and equipment requirements for an automated classification survey, are discussed. A program of auxiliary observations is proposed to yield spectral types and radial velocities for the GAIA-observed stars.

  6. Life comparative analysis of energy consumption and CO₂ emissions of different building structural frame types.

    PubMed

    Kim, Sangyong; Moon, Joon-Ho; Shin, Yoonseok; Kim, Gwang-Hee; Seo, Deok-Seok

    2013-01-01

    The objective of this research is to quantitatively measure and compare the environmental load and construction cost of different structural frame types. Construction cost also accounts for the costs of CO₂ emissions of input materials. The choice of structural frame type is a major consideration in construction, as this element represents about 33% of total building construction costs. In this research, four constructed buildings were analyzed, with these having either reinforced concrete (RC) or steel (S) structures. An input-output framework analysis was used to measure energy consumption and CO₂ emissions of input materials for each structural frame type. In addition, the CO₂ emissions cost was measured using the trading price of CO₂ emissions on the International Commodity Exchange. This research revealed that both energy consumption and CO₂ emissions were, on average, 26% lower with the RC structure than with the S structure, and the construction costs (including the CO₂ emissions cost) of the RC structure were about 9.8% lower, compared to the S structure. This research provides insights through which the construction industry will be able to respond to the carbon market, which is expected to continue to grow in the future.

  7. Life Comparative Analysis of Energy Consumption and CO2 Emissions of Different Building Structural Frame Types

    PubMed Central

    Kim, Sangyong; Moon, Joon-Ho; Shin, Yoonseok; Kim, Gwang-Hee; Seo, Deok-Seok

    2013-01-01

    The objective of this research is to quantitatively measure and compare the environmental load and construction cost of different structural frame types. Construction cost also accounts for the costs of CO2 emissions of input materials. The choice of structural frame type is a major consideration in construction, as this element represents about 33% of total building construction costs. In this research, four constructed buildings were analyzed, with these having either reinforced concrete (RC) or steel (S) structures. An input-output framework analysis was used to measure energy consumption and CO2 emissions of input materials for each structural frame type. In addition, the CO2 emissions cost was measured using the trading price of CO2 emissions on the International Commodity Exchange. This research revealed that both energy consumption and CO2 emissions were, on average, 26% lower with the RC structure than with the S structure, and the construction costs (including the CO2 emissions cost) of the RC structure were about 9.8% lower, compared to the S structure. This research provides insights through which the construction industry will be able to respond to the carbon market, which is expected to continue to grow in the future. PMID:24227998

  8. Comparing Broad-Band and Red Edge-Based Spectral Vegetation Indices to Estimate Nitrogen Concentration of Crops Using Casi Data

    NASA Astrophysics Data System (ADS)

    Wang, Yanjie; Liao, Qinhong; Yang, Guijun; Feng, Haikuan; Yang, Xiaodong; Yue, Jibo

    2016-06-01

    In recent decades, many spectral vegetation indices (SVIs) have been proposed to estimate the leaf nitrogen concentration (LNC) of crops. However, most of these indices were based on the field hyperspectral reflectance. To test whether they can be used in aerial remote platform effectively, in this work a comparison of the sensitivity between several broad-band and red edge-based SVIs to LNC is investigated over different crop types. By using data from experimental LNC values over 4 different crop types and image data acquired using the Compact Airborne Spectrographic Imager (CASI) sensor, the extensive dataset allowed us to evaluate broad-band and red edge-based SVIs. The result indicated that NDVI performed the best among the selected SVIs while red edge-based SVIs didn't show the potential for estimating the LNC based on the CASI data due to the spectral resolution. In order to search for the optimal SVIs, the band combination algorithm has been used in this work. The best linear correlation against the experimental LNC dataset was obtained by combining the 626.20nm and 569.00nm wavebands. These wavelengths correspond to the maximal chlorophyll absorption and reflection position region, respectively, and are known to be sensitive to the physiological status of the plant. Then this linear relationship was applied to the CASI image for generating an LNC map, which can guide farmers in the accurate application of their N fertilization strategies.

  9. Abnormal selective area growth of irregularly-shaped GaN structures on the apex of GaN pyramids and its application for wide spectral emission

    NASA Astrophysics Data System (ADS)

    Yu, Yeon Su; Lee, Jun Hyeong; Ahn, Hyung Soo; Yang, Min

    2014-12-01

    We report on the growth and the characterization of three-dimensional randomly-shaped InGaN/GaN structures selectively grown on the apex of GaN pyramids for the purpose of enlarging the emission spectral range. We found that the variations in the shape and the size of the three-dimensional GaN structures depend on the growth temperature and the surface area for selective growth under intentional turbulence in the gas stream. The selectively grown GaN structures grown at 1020 °C have irregular shape, while the samples grown at 1100 °C have rather uniform hexagonal pyramidal shapes. Irregularly shaped GaN structures were also obtained on the apex of GaN pyramids when the SiO2 mask was removed to 1/10 of the total height of the underlying GaN pyramid. When only 1/5 of the SiO2 mask was removed, however, the selectively grown GaN structures had similar hexagonal pyramidal shapes resembling those of the underlying GaN pyramids. The CL (Cathodoluminescence) spectra of the InGaN layers grown on the randomly shaped GaN structures showed a wide emission spectral range from 388 to 433 nm due to the non-uniform thickness and spatially inhomogeneous indium composition of the InGaN layers. This new selective growth method might have great potential for applications of non-phosphor white light emitting diodes (LEDs) with optimized growth conditions for InGaN active layers of high indium composition and with optimum process for fabrication of electrodes for electrical injection.

  10. A comparative overview of modal testing and system identification for control of structures

    NASA Technical Reports Server (NTRS)

    Juang, J.-N.; Pappa, R. S.

    1988-01-01

    A comparative overview is presented of the disciplines of modal testing used in structural engineering and system identification used in control theory. A list of representative references from both areas is given, and the basic methods are described briefly. Recent progress on the interaction of modal testing and control disciplines is discussed. It is concluded that combined efforts of researchers in both disciplines are required for unification of modal testing and system identification methods for control of flexible structures.

  11. [Plant Spectral Discrimination Based on Phenological Features].

    PubMed

    Zhang, Lei; Zhao, Jian-long; Jia, Kun; Li, Xiao-song

    2015-10-01

    Spectral analysis plays a significant role onplant characteristic identification and mechanism recognition, there were many papers published on the aspects of absorption features in the spectra of chlorophyll and moisture, spectral analysis onvegetation red edge effect, spectra profile feature extraction, spectra profile conversion, vegetation leaf structure and chemical composition impacts on the spectra in past years. However, fewer researches issued on spectral changes caused by plant seasonal changes of life form, chlorophyll, leaf area index. This paper studied on spectral observation of 11 plants of various life form, plant leaf structure and its size, phenological characteristics, they include deciduous forest with broad vertical leaf, needle leaf evergreen forest, needle leaf deciduous forest, deciduous forest with broadflat leaf, high shrub with big leaf, high shrub with little leaf, deciduous forest with broad little leaf, short shrub, meadow, steppe and grass. Field spectral data were observed with SVC-HR768 (Spectra Vista company, USA), the band width covers 350-2 500 nm, spectral resolution reaches 1-4 nm. The features of NDVI, spectral maximum absorption depth in green band, and spectral maximum absorption depth in red band were measured after continuum removal processing, the mean, amplitude and gradient of these features on seasonal change profile were analyzed, meanwhile, separability research on plant spectral feature of growth period and maturation period were compared. The paper presents a calculation method of separability of vegetation spectra which consider feature spatial distances. This index is carried on analysis of the vegetation discrimination. The results show that: the spectral features during plant growth period are easier to distinguish than them during maturation period. With the same features comparison, plant separability of growth period is 3 points higher than it during maturation period. The overall separabilityof vegetation

  12. Spectral Predictors

    SciTech Connect

    Ibarria, L; Lindstrom, P; Rossignac, J

    2006-11-17

    Many scientific, imaging, and geospatial applications produce large high-precision scalar fields sampled on a regular grid. Lossless compression of such data is commonly done using predictive coding, in which weighted combinations of previously coded samples known to both encoder and decoder are used to predict subsequent nearby samples. In hierarchical, incremental, or selective transmission, the spatial pattern of the known neighbors is often irregular and varies from one sample to the next, which precludes prediction based on a single stencil and fixed set of weights. To handle such situations and make the best use of available neighboring samples, we propose a local spectral predictor that offers optimal prediction by tailoring the weights to each configuration of known nearby samples. These weights may be precomputed and stored in a small lookup table. We show that predictive coding using our spectral predictor improves compression for various sources of high-precision data.

  13. Synthesis, molecular structure, spectral analysis, and biological activity of new malonamide derivatives as α-glucosidase inhibitors

    NASA Astrophysics Data System (ADS)

    Barakat, Assem; Islam, Mohammad Shahidul; Al-Majid, Abdullah Mohammed; Soliman, Saied M.; Ghabbour, Hazem A.; Yousuf, Sammer; Choudhary, M. Iqbal; Ul-Haq, Zaheer

    2017-04-01

    Two new malonamide derivatives were synthesized via the Michael addition of N1,N3-di(pyridin-2-yl)malonamide to α,β-unsaturated ketones using a 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) catalyst at room temperature. All reactions efficiently furnished the desired malonamide derivatives, which differed only in their substitution on one phenyl group, with one derivative bearing a bromine substituent and the other bearing a methyl group. The structures of newly synthesized compounds were then elucidated by single-crystal X-ray diffraction, infrared spectroscopy, NMR spectroscopy, mass spectrometry, and elemental analysis. In addition, the synthesized compounds were evaluated for their in vitro cytotoxicity against cancer cell lines and for α-glucosidase inhibition. The target compounds exhibited enhanced α-glucosidase inhibition activity (i.e., IC50 = 12.8 ± 0.1 and 28.4 ± 0.2 μM) compared to the common drug acarbose (IC50 = 840 ± 1.73 μM). Both compounds were found to be non-cytotoxic against H460 (lung carcinoma) and T3T (normal fibroblast) cell lines. In addition, the bromo-substituted derivative exhibited weak cytotoxic against cervical cancer HeLa (IC50 = 13.8 ± 0.4 μM) and breast cancer MCF-7 (IC50 = 21.11 ± 0.88 μM) cell lines, while the methyl-substituted derivative showed weak cytotoxicity against the MCF-7 cell line (IC50 = 47.9 ± 0.7 μM). Density functional theory (DFT) B3LYP/6-311G(d,p) calculations were employed to examine the molecular structures and electronic properties of the prepared compounds. As expected, the bromo-derivative (2.2377 D) exhibited a higher polarity than the methyl-derivative (1.9160 D). Furthermore, the HOMO and LUMO diagrams were constructed and the electronic spectra of both compounds were assigned using time-dependent (TD)-DFT calculations. Finally, the calculated NMR chemical shifts correlated well with the experimental data.

  14. Hassle free synthesis of nanodimensional Ni, Cu and Zn sulfides for spectral sensing of Hg, Cd and Pb: A comparative study

    NASA Astrophysics Data System (ADS)

    Ansari, Zarina; Singha, Shib Shankar; Saha, Abhijit; Sen, Kamalika

    2017-04-01

    A simple room temperature synthesis method of Ni, Cu and Zn sulfide nanoparticles (NPs) in aqueous medium is reported here. The NPs stabilized in aqueous medium by the citrate ions were characterized by UV-vis, ζ potentials, TEM and Raman spectroscopic techniques. The solid NPs could be isolated from the aqueous medium when allowed to stand for a prolonged time ( 20 h). The solids were also characterized by IR and powder X-ray analysis. The nanoparticles were further used for the development of facile optical sensing and detection of heavy metal ions at trace scale. Alterations in the absorption spectra of the generated NPs were indicative of their interactions with heavy metal ions. Raman spectral measurements further validate the detection technique. It is found that out of the three synthesized nanoparticles, nickel sulfide NP is a specific sensor for mercury ions whereas zinc sulfide and copper sulfide NPs act as sensors for Hg2 +, Cd2 + and Pb2 +.

  15. Hassle free synthesis of nanodimensional Ni, Cu and Zn sulfides for spectral sensing of Hg, Cd and Pb: A comparative study.

    PubMed

    Ansari, Zarina; Singha, Shib Shankar; Saha, Abhijit; Sen, Kamalika

    2017-04-05

    A simple room temperature synthesis method of Ni, Cu and Zn sulfide nanoparticles (NPs) in aqueous medium is reported here. The NPs stabilized in aqueous medium by the citrate ions were characterized by UV-vis, ζ potentials, TEM and Raman spectroscopic techniques. The solid NPs could be isolated from the aqueous medium when allowed to stand for a prolonged time (~20h). The solids were also characterized by IR and powder X-ray analysis. The nanoparticles were further used for the development of facile optical sensing and detection of heavy metal ions at trace scale. Alterations in the absorption spectra of the generated NPs were indicative of their interactions with heavy metal ions. Raman spectral measurements further validate the detection technique. It is found that out of the three synthesized nanoparticles, nickel sulfide NP is a specific sensor for mercury ions whereas zinc sulfide and copper sulfide NPs act as sensors for Hg(2+), Cd(2+) and Pb(2+).

  16. A comprehensive comparative test of seven widely used spectral synthesis models against multi-band photometry of young massive-star clusters

    NASA Astrophysics Data System (ADS)

    Wofford, A.; Charlot, S.; Bruzual, G.; Eldridge, J. J.; Calzetti, D.; Adamo, A.; Cignoni, M.; de Mink, S. E.; Gouliermis, D. A.; Grasha, K.; Grebel, E. K.; Lee, J. C.; Östlin, G.; Smith, L. J.; Ubeda, L.; Zackrisson, E.

    2016-04-01

    We test the predictions of spectral synthesis models based on seven different massive-star prescriptions against Legacy ExtraGalactic UV Survey (LEGUS) observations of eight young massive clusters in two local galaxies, NGC 1566 and NGC 5253, chosen because predictions of all seven models are available at the published galactic metallicities. The high angular resolution, extensive cluster inventory, and full near-ultraviolet to near-infrared photometric coverage make the LEGUS data set excellent for this study. We account for both stellar and nebular emission in the models and try two different prescriptions for attenuation by dust. From Bayesian fits of model libraries to the observations, we find remarkably low dispersion in the median E(B - V) (˜0.03 mag), stellar masses (˜104 M⊙), and ages (˜1 Myr) derived for individual clusters using different models, although maximum discrepancies in these quantities can reach 0.09 mag and factors of 2.8 and 2.5, respectively. This is for ranges in median properties of 0.05-0.54 mag, 1.8-10 × 104 M⊙, and 1.6-40 Myr spanned by the clusters in our sample. In terms of best fit, the observations are slightly better reproduced by models with interacting binaries and least well reproduced by models with single rotating stars. Our study provides a first quantitative estimate of the accuracies and uncertainties of the most recent spectral synthesis models of young stellar populations, demonstrates the good progress of models in fitting high-quality observations, and highlights the needs for a larger cluster sample and more extensive tests of the model parameter space.

  17. Spectral energy distribution simulations of a possible ring structure around the young, red brown dwarf G 196-3 B

    NASA Astrophysics Data System (ADS)

    Zakhozhay, Olga V.; Zapatero Osorio, María Rosa; Béjar, Víctor J. S.; Boehler, Yann

    2017-01-01

    The origin of the very red optical and infrared colours of intermediate-age (˜10-500 Myr) L-type dwarfs remains unknown. It has been suggested that low-gravity atmospheres containing large amounts of dust may account for the observed reddish nature. We explored an alternative scenario by simulating debris disc around G 196-3 B, which is an L3 young brown dwarf with a mass of ˜15 MJup and an age in the interval 20-300 Myr. The best-fit solution to G 196-3 B's photometric spectral energy distribution from optical wavelengths through 24 μm corresponds to the combination of an unreddened L3 atmosphere (Teff ≈ 1870 K) and a warm (≈1280 K), narrow (≈0.07-0.11 R⊙) debris disc located at very close distances (≈0.12-0.20 R⊙) from the central brown dwarf. This putative, optically thick, dusty belt, whose presence is compatible with the relatively young system age, would have a mass ≥7 × 10-10 M⊕ comprised of submicron/micron characteristic dusty particles with temperatures close to the sublimation threshold of silicates. Considering the derived global properties of the belt and the disc-to-brown dwarf mass ratio, the dusty ring around G 196-3 B may resemble the rings of Neptune and Jupiter, except for its high temperature and thick vertical height (≈6 × 103 km). Our inferred debris disc model is able to reproduce G 196-3 B's spectral energy distribution to a satisfactory level of achievement.

  18. Synthesis, spectral, thermal, optical, electrical, mechanical and structural characterisations and quantum chemical study of 4-nitrophenol: Urea molecular adduct crystals

    NASA Astrophysics Data System (ADS)

    Muthuraja, P.; Sethuram, M.; Sethu Raman, M.; Dhandapani, M.; Amirthaganesan, G.

    2013-12-01

    Organic non-linear single crystals of 4-Nitrophenol: Urea Adduct (NPUA) have been grown by slow evaporation-solution growth technique. The elemental analysis of the compound satisfies the stoichiometric expectations. Vibrational frequencies of the grown crystals have been identified by using FT-IR analysis. The presence of different protons and carbon atoms of the grown adduct was ascertained by 1H and 13C NMR analyses. The UV-Visible spectroscopy study revealed that the grown crystal has excellent transmittance and has wide band gap in the visible province. The fluorescence emission spectrum has also been recorded. Photoconductivity studies confirm positive photoconductivity nature of the crystals. The crystal belongs to the triclinic system with space group P1. The complete structural analysis of the grown crystal has been done using single crystal X-ray diffraction technique. Thermogravimetry (TG), Differential Thermal Analysis (DTA) and Differential Scanning Calorimetry (DSC) were carried out to characterise the thermal behaviour and stability of NPUA. Dielectric studies have been carried out at room temperature. Mechanical behaviour of NPUA was studied by Vickers's microhardness test. The nonlinear optical (NLO) activity test using a Q-switched and pulsed Nd: YAG laser confirms the generation of second harmonics. The Density Functional Theoretical (DFT) study affords further insight on the properties of the compound. Quantum Chemical Calculations (QCC) have been performed through DFT method at B3LYP/6-31G(d) level of theory. The optimised geometric parameters such as bond lengths, bond angles, dipole moment, optimisation energy and vibrational frequencies were reported and compared with the experimental data.

  19. Gender Differences in Structured Risk Assessment: Comparing the Accuracy of Five Instruments

    ERIC Educational Resources Information Center

    Coid, Jeremy; Yang, Min; Ullrich, Simone; Zhang, Tianqiang; Sizmur, Steve; Roberts, Colin; Farrington, David P.; Rogers, Robert D.

    2009-01-01

    Structured risk assessment should guide clinical risk management, but it is uncertain which instrument has the highest predictive accuracy among men and women. In the present study, the authors compared the Psychopathy Checklist-Revised (PCL-R; R. D. Hare, 1991, 2003); the Historical, Clinical, Risk Management-20 (HCR-20; C. D. Webster, K. S.…

  20. Belief Structure and Foreign Policy: Comparing Dimensions of Elite and Mass Opinion.

    ERIC Educational Resources Information Center

    Oldendick, Robert, And Others

    1981-01-01

    This study compares the dimensions of elite (political leaders) and mass (general public) opinions towards foreign policy. A factor analysis revealed the elite's five major concerns (internationalism, international organization, Americanism, defense spending, and interventionism) and an overall preference for structured approaches. The masses also…

  1. Estimating, Testing, and Comparing Specific Effects in Structural Equation Models: The Phantom Model Approach

    ERIC Educational Resources Information Center

    Macho, Siegfried; Ledermann, Thomas

    2011-01-01

    The phantom model approach for estimating, testing, and comparing specific effects within structural equation models (SEMs) is presented. The rationale underlying this novel method consists in representing the specific effect to be assessed as a total effect within a separate latent variable model, the phantom model that is added to the main…

  2. Associational Structure and Community Development: A Comparative Study of Two Communities

    ERIC Educational Resources Information Center

    Dasgupta, Satadal

    1974-01-01

    The two communities compared tended to support the proposition that communities following an integrative style of development are characterized by coordinative structures including associational, while the contrary is true for communities following the autonomous style. Available from: Editorial and Business Offices, Piazza Cavalieri di Malta, 2,…

  3. Comparing Religious Education in Canadian and Australian Catholic High Schools: Identifying Some Key Structural Issues

    ERIC Educational Resources Information Center

    Rymarz, Richard

    2013-01-01

    Religious education (RE) in Catholic high schools in Australia and Canada is compared by examining some of the underlying structural factors that shape the delivery of RE. It is argued that in Canadian Catholic schools RE is diminished by three factors that distinguish it from the Australian experience. These are: the level and history of…

  4. Linguistic Structure and Non-linguistic Cognition: English and Russian Blues Compared.

    ERIC Educational Resources Information Center

    Laws, Glynis; And Others

    1995-01-01

    Investigates the influence of linguistic structure on non-linguistic cognition by comparing Russian and English behavior on tasks involving the color blue. Russians, who differentiate this region into "dark blue" and "light blue," were expected to separate blues more often than English subjects for whom the colors belong to one lexical category.…

  5. The Company That Words Keep: Comparing the Statistical Structure of Child- versus Adult-Directed Language

    ERIC Educational Resources Information Center

    Hills, Thomas

    2013-01-01

    Does child-directed language differ from adult-directed language in ways that might facilitate word learning? Associative structure (the probability that a word appears with its free associates), contextual diversity, word repetitions and frequency were compared longitudinally across six language corpora, with four corpora of language directed at…

  6. Excitonic energy level structure and pigment-protein interactions in the recombinant water-soluble chlorophyll protein. II. Spectral hole-burning experiments.

    PubMed

    Pieper, J; Rätsep, M; Trostmann, I; Schmitt, F-J; Theiss, C; Paulsen, H; Eichler, H J; Freiberg, A; Renger, G

    2011-04-14

    Persistent spectral hole burning at 4.5 K has been used to investigate the excitonic energy level structure and the excited state dynamics of the recombinant class-IIa water-soluble chlorophyll-binding protein (WSCP) from cauliflower. The hole-burned spectra are composed of four main features: (i) a narrow zero-phonon hole (ZPH) at the burn wavelength, (ii) a number of vibrational ZPHs, (iii) a broad low-energy hole at ~665 and ~683 nm for chlorophyll b- and chlorophyll a-WSCP, respectively, and (iv) a second satellite hole at ~658 and ~673 nm for chlorophyll b- and chlorophyll a-WSCP, respectively. The doublet of broad satellite holes is assigned to an excitonically coupled chlorophyll dimer. The lower-energy holes at ~665 and ~683 nm for chlorophyll b- and chlorophyll a-WSCP, respectively, represent the lower exciton states. Taking into account the parameters of electron-phonon coupling, the lower exciton state can be assigned as the fluorescence origin. The lower exciton state is populated by two processes: (i) exciton relaxation from the higher exciton state and (ii) vibrational relaxation within the lower exciton state. Assuming identical site energies for the two excitonically coupled chlorophyll molecules, the dipole-dipole interaction energy J is directly determined to be 85 and 100 cm(-1) for chlorophyll b- and chlorophyll a-WSCP, respectively, based on the positions of the satellite holes. The Gaussian low-energy absorption band identified by constant fluence hole burning at 4.5 K has a width of ~150 cm(-1) and peaks at 664.9 and 682.7 nm for chlorophyll b- and chlorophyll a-WSCP, respectively. The action spectrum is broader and blue-shifted compared to the fluorescent lower exciton state. This finding can be explained by a slow protein relaxation between energetically inequivalent conformational substates within the lowest exciton state in agreement with the results of Schmitt et al. (J. Phys. Chem. B2008, 112, 13951).

  7. Comparative Reliability of Structured Versus Unstructured Interviews in the Admission Process of a Residency Program

    PubMed Central

    Blouin, Danielle; Day, Andrew G.; Pavlov, Andrey

    2011-01-01

    Background Although never directly compared, structured interviews are reported as being more reliable than unstructured interviews. This study compared the reliability of both types of interview when applied to a common pool of applicants for positions in an emergency medicine residency program. Methods In 2008, one structured interview was added to the two unstructured interviews traditionally used in our resident selection process. A formal job analysis using the critical incident technique guided the development of the structured interview tool. This tool consisted of 7 scenarios assessing 4 of the domains deemed essential for success as a resident in this program. The traditional interview tool assessed 5 general criteria. In addition to these criteria, the unstructured panel members were asked to rate each candidate on the same 4 essential domains rated by the structured panel members. All 3 panels interviewed all candidates. Main outcomes were the overall, interitem, and interrater reliabilities, the correlations between interview panels, and the dimensionality of each interview tool. Results Thirty candidates were interviewed. The overall reliability reached 0.43 for the structured interview, and 0.81 and 0.71 for the unstructured interviews. Analyses of the variance components showed a high interrater, low interitem reliability for the structured interview, and a high interrater, high interitem reliability for the unstructured interviews. The summary measures from the 2 unstructured interviews were significantly correlated, but neither was correlated with the structured interview. Only the structured interview was multidimensional. Conclusions A structured interview did not yield a higher overall reliability than both unstructured interviews. The lower reliability is explained by a lower interitem reliability, which in turn is due to the multidimensionality of the interview tool. Both unstructured panels consistently rated a single dimension, even when

  8. Comparative evaluation of structured oil systems: Shellac oleogel, HPMC oleogel, and HIPE gel.

    PubMed

    Patel, Ashok R; Dewettinck, Koen

    2015-11-01

    In lipid-based food products, fat crystals are used as building blocks for creating a crystalline network that can trap liquid oil into a 3D gel-like structure which in turn is responsible for the desirable mouth feel and texture properties of the food products. However, the recent ban on the use of trans-fat in the US, coupled with the increasing concerns about the negative health effects of saturated fat consumption, has resulted in an increased interest in the area of identifying alternative ways of structuring edible oils using non-fat-based building blocks. In this paper, we give a brief account of three alternative approaches where oil structuring was carried out using wax crystals (shellac), polymer strands (hydrophilic cellulose derivative), and emulsion droplets as structurants. These building blocks resulted in three different types of oleogels that showed distinct rheological properties and temperature functionalities. The three approaches are compared in terms of the preparation process (ease of processing), properties of the formed systems (microstructure, rheological gel strength, temperature response, effect of water incorporation, and thixotropic recovery), functionality, and associated limitations of the structured systems. The comparative evaluation is made such that the new researchers starting their work in the area of oil structuring can use this discussion as a general guideline.

  9. Inferring spectral characteristics of the Hα spectral line observed by the DOT Lyot filter

    NASA Astrophysics Data System (ADS)

    Koza, J.; Rybák, J.; Gömöry, P.; Kučera, A.

    2014-04-01

    A tunable Lyot filter can serve as a spectroscopic device rendering wide-field 2-D pseudospectroscopy of solar structures and follow-up crude reconstruction of a spectral line profile at each pixel within the field of view. We developed a method of inferring of the Doppler shift, the core intensity, the core width, and the core asymmetry of the Hα spectral line observed by the Lyot filter installed on the Dutch Open Telescope (DOT). The spectral characteristics are inferred through the fitting of five intensity samples, separated from each other by 0.35 Å, by a 4th-order polynomial, a Gaussian, and a parabola. We use the atlas Hα profile as a reference in estimating deviations of the derived spectral characteristics. The Gaussian is the most preferable means for measurements of the Doppler shift with deviations smaller than 1 km s-1. When using the 4th-order polynomial, deviations are within the interval ±2.5 km s-1, but it renders comparable deviations of the core intensity and the width as the Gaussian. The deviations are largely insensitive to the shape of the filter transmission, but depend mostly non-linearly on the Doppler shift. Therefore, they do not cancel out if the spectral characteristics are represented by their relative variations. Results can be used as corrections of spectral characteristics extracted from area-averaged Hα profiles acquired by the DOT Lyot filter.

  10. Statistical Power of Alternative Structural Models for Comparative Effectiveness Research: Advantages of Modeling Unreliability

    PubMed Central

    Iordache, Eugen; Dierker, Lisa; Fifield, Judith; Schensul, Jean J.; Suggs, Suzanne; Barbour, Russell

    2015-01-01

    The advantages of modeling the unreliability of outcomes when evaluating the comparative effectiveness of health interventions is illustrated. Adding an action-research intervention component to a regular summer job program for youth was expected to help in preventing risk behaviors. A series of simple two-group alternative structural equation models are compared to test the effect of the intervention on one key attitudinal outcome in terms of model fit and statistical power with Monte Carlo simulations. Some models presuming parameters equal across the intervention and comparison groups were underpowered to detect the intervention effect, yet modeling the unreliability of the outcome measure increased their statistical power and helped in the detection of the hypothesized effect. Comparative Effectiveness Research (CER) could benefit from flexible multi-group alternative structural models organized in decision trees, and modeling unreliability of measures can be of tremendous help for both the fit of statistical models to the data and their statistical power. PMID:26640421

  11. Structural and vibrational spectroscopic analysis of anticancer drug mitotane using DFT method; a comparative study of its parent structure

    NASA Astrophysics Data System (ADS)

    Mariappan, G.; Sundaraganesan, N.

    2015-04-01

    A comprehensive screening of the density functional theoretical approach to structural analysis is presented in this section. DFT calculations using B3LYP/6-311++G(d,p) level of theory were found to yield results that are very comparable to experimental IR and Raman spectra. Computed geometrical parameters and harmonic vibrational wavenumbers of the fundamentals were found in satisfactory agreement with the experimental data and also its parent structure. The vibrational assignments of the normal modes were performed on the basis of the potential energy distribution (PED) calculations. It can be proven from the comparative results of mitotane and its parent structure Dichlorodiphenyldichloroethane (DDD), the intramolecular nonbonding interaction between (C1sbnd H19⋯Cl18) in the ortho position which is calculated 2.583 Å and the position of the substitution takeover the vibrational wavenumber to redshift of 47 cm-1. In addition, natural bond orbital (NBO) analysis has been performed for analyzing charge delocalization throughout the molecule. Stability of the molecule arising from hyperconjugative interactions leading to its bioactivity and charge delocalization has been analyzed. 13C and 1H nuclear magnetic resonance chemical shifts of the molecule have been calculated using the gauge independent atomic orbital (GIAO) method and compared with published results.

  12. [A Terahertz Spectral Database Based on Browser/Server Technique].

    PubMed

    Zhang, Zhuo-yong; Song, Yue

    2015-09-01

    With the solution of key scientific and technical problems and development of instrumentation, the application of terahertz technology in various fields has been paid more and more attention. Owing to the unique characteristic advantages, terahertz technology has been showing a broad future in the fields of fast, non-damaging detections, as well as many other fields. Terahertz technology combined with other complementary methods can be used to cope with many difficult practical problems which could not be solved before. One of the critical points for further development of practical terahertz detection methods depends on a good and reliable terahertz spectral database. We developed a BS (browser/server) -based terahertz spectral database recently. We designed the main structure and main functions to fulfill practical requirements. The terahertz spectral database now includes more than 240 items, and the spectral information was collected based on three sources: (1) collection and citation from some other abroad terahertz spectral databases; (2) collected from published literatures; and (3) spectral data measured in our laboratory. The present paper introduced the basic structure and fundament functions of the terahertz spectral database developed in our laboratory. One of the key functions of this THz database is calculation of optical parameters. Some optical parameters including absorption coefficient, refractive index, etc. can be calculated based on the input THz time domain spectra. The other main functions and searching methods of the browser/server-based terahertz spectral database have been discussed. The database search system can provide users convenient functions including user registration, inquiry, displaying spectral figures and molecular structures, spectral matching, etc. The THz database system provides an on-line searching function for registered users. Registered users can compare the input THz spectrum with the spectra of database, according to

  13. Structures, properties, and functions of the stings of honey bees and paper wasps: a comparative study

    PubMed Central

    Zhao, Zi-Long; Zhao, Hong-Ping; Ma, Guo-Jun; Wu, Cheng-Wei; Yang, Kai; Feng, Xi-Qiao

    2015-01-01

    ABSTRACT Through natural selection, many animal organs with similar functions have evolved different macroscopic morphologies and microscopic structures. Here, we comparatively investigate the structures, properties and functions of honey bee stings and paper wasp stings. Their elegant structures were systematically observed. To examine their behaviors of penetrating into different materials, we performed penetration–extraction tests and slow motion analyses of their insertion process. In comparison, the barbed stings of honey bees are relatively difficult to be withdrawn from fibrous tissues (e.g. skin), while the removal of paper wasp stings is easier due to their different structures and insertion skills. The similarities and differences of the two kinds of stings are summarized on the basis of the experiments and observations. PMID:26002929

  14. Application of comparative vibrational spectroscopic and mechanistic studies in analysis of fisetin structure

    NASA Astrophysics Data System (ADS)

    Dimitrić Marković, Jasmina M.; Marković, Zoran S.; Milenković, Dejan; Jeremić, Svetlana

    2011-12-01

    This paper addresses experimental and theoretical research in fisetin (2-(3,4-dihydroxyphenyl)-3,7-dihydroxychromen-4-one) structure by means of experimental IR and Raman spectroscopies and mechanistic calculations. Density Functional Theory calculations, with M05-2X functional and the 6-311+G (2df, p) basis set implemented in the Gaussian 09 package, are performed with the aim to support molecular structure, vibrational bands' positions and their intensities. Potential energy distribution (PED) values and the description of the largest vibrational contributions to the normal modes are calculated. The most intense bands appear in the 1650-1500 cm -1 wavenumber region. This region involves a combination of the C dbnd O, C2 dbnd C3 and C-C stretching vibrational modes. Most of the bands in the 1500-1000 cm -1 range involve C-C stretching, O-C stretching and in-plane C-C-H, C-O-H, C-C-O and C-C-C bending vibrations of the rings. The region below 1000 cm -1 is characteristic to the combination of in plane C-C-C-H, H-C-C-H, C-C-C-C, C-C-O-C and out of plane O-C-C-C, C-C-O-C, C-C-C-C torsional modes. The Raman spectra of baicalein and quercetin were used for qualitative comparison with fisetin spectrum and verification of band assignments. The applied detailed vibrational spectral analysis and the assignments of the bands, proposed on the basis of fundamentals, reproduced the experimental results with high degree of accuracy.

  15. Space-time and Spectral Structures of Sprite Halos Obtained from High-speed Photometric and Imaging Observations

    NASA Astrophysics Data System (ADS)

    Miyasato, R.; Fukunishi, H.; Taylor, M. J.; Stenbaek-Nielsen, H. C.

    2001-12-01

    We carried out optical observations of lightning-induced luminous events at Yucca Ridge Field Station, Colorado, USA, from 1996 to 2000, using two multi-anode array photometers (MAP), an image intensified CCD cameras and other optical instruments. The MAP has 16 channels aligned vertically and each channel has a field-of-view of 0.67x10.75 degrees. Consequently, the total size of field-of-view is 10.75x10.75 degrees. The time resolution of MAP is 50 microseconds so that we can detect temporal and spatial structures of sprite halo emissions. The two MAPs are equipped with different color filters, red (380-500 nm) for mesurement of N2 1st positive band and N2+ Meinel band, and blue (560-800 nm) for mesurement of N2 2nd positive band and N2+ 1st negative band, respectively. Using data obtained from these instruments, we estimated the altitude range and the horizontal extent of sprite halos. Sprite halos move downward as focusing into the center of diffuse glows. It is found that the starting and ending altitudes are about 83 and 67 km, respectively, on average, and that the mean speed of downward motion is about 1/6 of the light speed. On the other hand, the estimated horizontal extent of sprite halos are about 40 - 110 km with a mean value of 78 km. A mean duration of sprite halos is found to be about 1 ms. Using the ratios of blue to red siganls obtained from two MAPs during the SPRITES'99 campaign, we estimated the energies of electrons inducing sprite halo emissions by assuming a more realistic non-Mawellian energy distribution as well as a standard Maxwell-Boltzmann distribution. Futhermore, we calculated the charge moments of causative CGs using NLDN data and investigated the relationship between the charge moments of causative CGs and the time delays from VLF sferics to the onset of sprite halos. By comparing the observational results with the model calculation presented by Barrington-Leigh et al. [2000], we will discuss the generation mechanism of sprite halos.

  16. Structural and spectral consequences of ion pairing. 4. Theoretical study of BF sub 4 sup minus M sup + (M = Li, Na, K, and Rb)

    SciTech Connect

    Francisco, J.S. ); Williams, I.H. )

    1990-11-15

    Ion pairs of BR{sub 4}{sup {minus}} anion with the cations Li{sup +}, Na{sup +}, K{sup +}, and Rb{sup +} have been studied by ab initio quantum-chemical methods. Optimized geometries for monodentate, bidentate, and tridentate structures have been determined at the HF/3-21 G and HF/6-31+G,3-21G levels of theory, and the energetics of these modes of coordination have been calculated with the inclusion of electron correlation by the MP2 and MP4 methods. The bidentate and tridentate structures for BF{sub 4}{sup {minus}}Li{sup +} have been studied at various levels of calculation up to MP2/6-311+G*//MP2/6-31G*. Vibrational frequencies, {sup 10}B isotope frequency shifts, and infrared intensities have been calculated at the HF/3-21G level for each ion pair and at the HF/6-31+G,3-21G level for the tridentate BF{sub 4}{sup {minus}}K{sup +} ion pair. The tridentate structure is preferred for Na{sup +}, K{sup +}, and Rb{sup +}, but the bidentate structure is preferred for Li{sup +}. The topological, structural, energetic, and spectral consequences of the changing nature of the cation in the ion pairs are discussed.

  17. SPAM- SPECTRAL ANALYSIS MANAGER (UNIX VERSION)

    NASA Technical Reports Server (NTRS)

    Solomon, J. E.

    1994-01-01

    The Spectral Analysis Manager (SPAM) was developed to allow easy qualitative analysis of multi-dimensional imaging spectrometer data. Imaging spectrometers provide sufficient spectral sampling to define unique spectral signatures on a per pixel basis. Thus direct material identification becomes possible for geologic studies. SPAM provides a variety of capabilities for carrying out interactive analysis of the massive and complex datasets associated with multispectral remote sensing observations. In addition to normal image processing functions, SPAM provides multiple levels of on-line help, a flexible command interpretation, graceful error recovery, and a program structure which can be implemented in a variety of environments. SPAM was designed to be visually oriented and user friendly with the liberal employment of graphics for rapid and efficient exploratory analysis of imaging spectrometry data. SPAM provides functions to enable arithmetic manipulations of the data, such as normalization, linear mixing, band ratio discrimination, and low-pass filtering. SPAM can be used to examine the spectra of an individual pixel or the average spectra over a number of pixels. SPAM also supports image segmentation, fast spectral signature matching, spectral library usage, mixture analysis, and feature extraction. High speed spectral signature matching is performed by using a binary spectral encoding algorithm to separate and identify mineral components present in the scene. The same binary encoding allows automatic spectral clustering. Spectral data may be entered from a digitizing tablet, stored in a user library, compared to the master library containing mineral standards, and then displayed as a timesequence spectral movie. The output plots, histograms, and stretched histograms produced by SPAM can be sent to a lineprinter, stored as separate RGB disk files, or sent to a Quick Color Recorder. SPAM is written in C for interactive execution and is available for two different

  18. Spectral, crystal structure, thermal and antimicrobial characterisation of an organic charge transfer complex-3,5-dimethylpyrrazolinium picrate

    NASA Astrophysics Data System (ADS)

    Dhanabal, T.; Amirthaganesan, G.; Dhandapani, M.; Das, Samar K.

    2013-03-01

    A novel organic charge transfer complex, 3,5-dimethylpyrrazolinium picrate was grown and crystallized by slow evaporation solution growth method at room temperature. The absorption of the grown crystal was studied using UV-visible spectral analysis and observed that the crystal possesses minimum absorption between 250 and 900 nm. The lower cut-off wavelength and the optical transmittance window were identified by optical transmittance study. The emission spectrum of the complex shows peaks at 505 and 758 nm are due to the green and red fluorescence emissions respectively. The thermogravimetry-differential thermal analyses (TG-DTA) were used to investigate the thermal stability of the complex. The single crystal X-ray diffraction method indicates that the complex crystallizes in monoclinic system with space group P2(1)/C. The FTIR and polarised Raman spectra were used to confirm the presence of various functional groups. The different kinds of protons and carbons were assigned through NMR (1H and 13C) spectroscopic techniques. The nonlinear optical property (NLO) of the material was studied by modified Kurtz-Perry powder technique. The complex exhibits good antibacterial and antifungal activities against various bacteria and fungi species.

  19. Comparative genomic analysis of equilibrative nucleoside transporters suggests conserved protein structure despite limited sequence identity.

    PubMed

    Sankar, Narendra; Machado, Jerry; Abdulla, Parween; Hilliker, Arthur J; Coe, Imogen R

    2002-10-15

    Equilibrative nucleoside transporters (ENTs) are a recently characterized and poorly understood group of membrane proteins that are important in the uptake of endogenous nucleosides required for nucleic acid and nucleoside triphosphate synthesis. Despite their central importance in cellular metabolism and nucleoside analog chemotherapy, no human ENT gene has been described and nothing is known about gene structure and function. To gain insight into the ENT gene family, we used experimental and in silico comparative genomic approaches to identify ENT genes in three evolutionarily diverse organisms with completely (or almost completely) sequenced genomes, Homo sapiens, Caenorhabditis elegans and Drosophila melanogaster. We describe the chromosomal location, the predicted ENT gene structure and putative structural topologies of predicted ENT proteins derived from the open reading frames. Despite variations in genomic layout and limited ortholog protein sequence identity (< or =27.45%), predicted topologies of ENT proteins are strikingly similar, suggesting an evolutionary conservation of a prototypic structure. In addition, a similar distribution of protein domains on exons is apparent in all three taxa. These data demonstrate that comparative sequence analyses should be combined with other approaches (such as genomic and proteomic analyses) to fully understand structure, function and evolution of protein families.

  20. The leader peptide of mutacin 1140 has distinct structural components compared to related class I lantibiotics.

    PubMed

    Escano, Jerome; Stauffer, Byron; Brennan, Jacob; Bullock, Monica; Smith, Leif

    2014-12-01

    Lantibiotics are ribosomally synthesized peptide antibiotics composed of an N-terminal leader peptide that promotes the core peptide's interaction with the post translational modification (PTM) enzymes. Following PTMs, mutacin 1140 is transported out of the cell and the leader peptide is cleaved to yield the antibacterial peptide. Mutacin 1140 leader peptide is structurally unique compared to other class I lantibiotic leader peptides. Herein, we further our understanding of the structural differences of mutacin 1140 leader peptide with regard to other class I leader peptides. We have determined that the length of the leader peptide is important for the biosynthesis of mutacin 1140. We have also determined that mutacin 1140 leader peptide contains a novel four amino acid motif compared to related lantibiotics. PTM enzyme recognition of the leader peptide appears to be evolutionarily distinct from related class I lantibiotics. Our study on mutacin 1140 leader peptide provides a basis for future studies aimed at understanding its interaction with the PTM enzymes.

  1. Compare of the electronic structures of F- and Ir-doped SmFeAsO

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Cheng, C. H.; Chen, Y. L.; Cui, Y. J.; You, W. G.; Zhang, H.; Zhao, Y.

    2010-11-01

    The electronic structures of Fe-based superconductor SmFeAsO1-xFx and SmFe1-yIryAsO are compared through X-ray photoemission spectroscopy in this study. With fluorine or iridium doping, the electronic structure and chemical environment of the SmFeAsO system were changed. The fluorine was doped at an oxygen site which introduced electrons to a reservoir Sm-O layer. The iridium was doped at an Fe site which introduced electrons to a conduction Fe-As layer directly. In a parent material SmFeAsO, the magnetic ordering corresponding to Fe3d in the low-spin state is suppressed by both fluorine and iridium doping through suppressing the magnetism of 3d itinerant electrons. Compared to fluorine doping, iridium doping affected superconductivity more significantly due to an iridium-induced disorder in FeAs layers.

  2. Comparative internal structure of dorsal lips and radiolar appendages in Sabellidae (Polychaeta) and phylogenetic implications.

    PubMed

    Capa, María; Nogueira, João Miguel de Matos; Rossi, Maíra Cappellani Silva

    2011-03-01

    Fan worms (Sabellidae) possess paired modified prostomial structures at the base of the radiolar crown, dorso-lateral to the mouth, called dorsal lips. The dorsal lips are involved in the sorting of particles collected by the radiolar crown. The range of variation in the morphology of dorsal lips is extensive, and probably this is not only due to adaptations to different environments and feeding preferences but also due to phylogenetic constraints. In this study, we describe and compare the morphology of dorsal lips in a range of sabellid taxa based on histological cross-sections of these structures, and compare our data and terminology with those of previous studies. Dorsal lips are maintained erect in most taxa by a modified radiole fused to them known as dorsal radiolar appendage. We suggest that dorsal radiolar appendages with an internal supporting axis (cellular or acellular) and probably also the ventral lips are synapomorphies of the family.

  3. Comparative structural and energetic analysis of WW domain-peptide interactions.

    PubMed

    Schleinkofer, Karin; Wiedemann, Urs; Otte, Livia; Wang, Ting; Krause, Gerd; Oschkinat, Hartmut; Wade, Rebecca C

    2004-11-26

    WW domains are small globular protein interaction modules found in a wide spectrum of proteins. They recognize their target proteins by binding specifically to short linear peptide motifs that are often proline-rich. To infer the determinants of the ligand binding propensities of WW domains, we analyzed 42 WW domains. We built models of the 3D structures of the WW domains and their peptide complexes by comparative modeling supplemented with experimental data from peptide library screens. The models provide new insights into the orientation and position of the peptide in structures of WW domain-peptide complexes that have not yet been determined experimentally. From a protein interaction property similarity analysis (PIPSA) of the WW domain structures, we show that electrostatic potential is a distinguishing feature of WW domains and we propose a structure-based classification of WW domains that expands the existent ligand-based classification scheme. Application of the comparative molecular field analysis (CoMFA), GRID/GOLPE and comparative binding energy (COMBINE) analysis methods permitted the derivation of quantitative structure-activity relationships (QSARs) that aid in identifying the specificity-determining residues within WW domains and their ligand-recognition motifs. Using these QSARs, a new group-specific sequence feature of WW domains that target arginine-containing peptides was identified. Finally, the QSAR models were applied to the design of a peptide to bind with greater affinity than the known binding peptide sequences of the yRSP5-1 WW domain. The prediction was verified experimentally, providing validation of the QSAR models and demonstrating the possibility of rationally improving peptide affinity for WW domains. The QSAR models may also be applied to the prediction of the specificity of WW domains with uncharacterized ligand-binding properties.

  4. The influence of In composition on properties of InxGa1-xAs/GaAs structures grown by MOVPE and in situ monitored by spectral reflectance

    NASA Astrophysics Data System (ADS)

    Bedoui, M.; Habchi, M. M.; Moussa, I.; Rebey, A.

    2017-01-01

    Series of InxGa1-xAs/GaAs structures with indium vapor composition ranging from 13 to 100%, denoted samples A, B, C and D, were grown by metalorganic vapor phase epitaxy (MOVPE) at 450 °C and in situ monitored by spectral reflectance (SR). In order to contribute to the enhancement of crystal quality and to understand growth kinetic of InxGa1-xAs/GaAs structures, the dependence of structural and morphological properties on indium composition x was studied. Basing on high resolution x-ray diffraction (HRXRD) measurements, solid indium compositions x of samples A, B, C and D were determined. Also, the evolution of structural quality (dislocations density, grain size, etc.) as a function of indium composition x was quantified. Besides, morphological properties (hatching and islands formations, densities, sizes and uniformities, RMS surface roughness, etc.) and growth process (growth anisotropy, etc.) versus indium composition x were examined using atomic force microscopy (AFM) analysis. Also, reflectance three-dimensional plot as function of time and wavelength was recorded to quantify the evolution of reflectivity in the wavelength range from 400 to 1000 nm and to determine some growth parameters such as growth rates and thicknesses of InxGa1-xAs samples. A good correlation between experimental results issued from different characterizations tools was obtained.

  5. Local structure and nanoscale homogeneity of CeO2-ZrO2: differences and similarities to parent oxides revealed by luminescence with temporal and spectral resolution.

    PubMed

    Tiseanu, Carmen; Parvulescu, Vasile; Avram, Daniel; Cojocaru, Bogdan; Boutonnet, Magali; Sanchez-Dominguez, Margarita

    2014-01-14

    Although homogeneity at the atomic level of CeO2-ZrO2 with a Ce/Zr atomic ratio close to unity is considered to be one of the main causes for the increased total oxygen storage capacity (OSC), the characterization approaches of homogeneity remain a major challenge. We propose a simple, yet effective method, to assess both structural and compositional homogeneity of CeO2-ZrO2 by using Eu(3+) luminescence measured with time and dual spectral resolution (emission and excitation). For Eu(3+)-CeO2-ZrO2 calcined at 750 °C, the X-ray diffraction, Raman and High-Resolution Transmission Electron Microscopy data converge to a single pseudo-cubic phase. However, the evolution of Eu(3+)-delayed luminescence from cubic ceria-like to tetragonal zirconia-like emission reveals the formation of CeO2- and ZrO2-rich nanodomains and provides evidence for early phase separation. For Eu(3+)-CeO2-ZrO2 calcined at 1000 °C, the emission of Eu(3+) reveals both structural and compositional inhomogeneity. Our study identifies the differences between the local structure properties of CeO2 and ZrO2 parent oxides and CeO2-ZrO2 mixed oxide, also confirming the special chemical environment of the oxygen atoms in the mixed oxide as reported earlier by Extended X-ray Absorption Fine Structure investigations.

  6. FT-IR, FT-Raman and UV spectral investigation; computed frequency estimation analysis and electronic structure calculations on 4-hydroxypteridine

    NASA Astrophysics Data System (ADS)

    Govindarajan, M.; Karabacak, M.

    2013-04-01

    In this work, the vibrational spectral analysis was carried out by using FT-Raman and FT-IR spectroscopy in the range 100-4000 cm-1 and 400-4000 cm-1 respectively, for 4-hydroxypteridine (C6H4N4O, 4HDPETN) molecule. The potential energy curve shows that 4HDPETN molecule has two stable structures. The computational results diagnose the most stable conformer of the 4HDPETN as the S1 structure. The molecular structure, fundamental vibrational frequencies and intensities of the vibrational bands were interpreted with the aid of structure optimizations and normal coordinate force field calculations based density functional theory (DFT) and ab initio HF methods and different basis sets combination. The complete vibrational assignments of wavenumbers were made on the basis of potential energy distribution (PED). The results of the calculations were applied to simulated spectra of the title compound, which show excellent agreement with observed spectra. The scaled B3LYP/6-311++G(d,p) results show the best agreement with the experimental values over the other method. The energy and oscillator strength calculated by time-dependent density functional theory (TD-DFT) complements with the experimental findings. In addition, molecular electrostatic potential, nonlinear optical and thermodynamic properties of the title compound were performed. Mulliken and natural charges of the title molecule were also calculated and interpreted.

  7. Agency and Structure as Determinants of Female Suicide Terrorism: A Comparative Study of Three Conflict Regions

    DTIC Science & Technology

    2009-12-01

    Agency and Structure as Determinants of Female Suicide Terrorism: A Comparative Study of Three Conflict Regions 6. AUTHOR( S ) Matthew P. Dearing 5...FUNDING NUMBERS 7. PERFORMING ORGANIZATION NAME( S ) AND ADDRESS(ES) Naval Postgraduate School Monterey, CA 93943-5000 8. PERFORMING ORGANIZATION...REPORT NUMBER 9. SPONSORING /MONITORING AGENCY NAME( S ) AND ADDRESS(ES) N/A 10. SPONSORING/MONITORING AGENCY REPORT NUMBER 11

  8. Spectral tunability of realistic plasmonic nanoantennas

    SciTech Connect

    Portela, Alejandro; Matsui, Hiroaki; Tabata, Hitoshi; Yano, Takaaki; Hayashi, Tomohiro; Hara, Masahiko; Santschi, Christian; Martin, Olivier J. F.

    2014-09-01

    Single nanoantenna spectroscopy was carried out on realistic dipole nanoantennas with various arm lengths and gap sizes fabricated by electron-beam lithography. A significant difference in resonance wavelength between realistic and ideal nanoantennas was found by comparing their spectral response. Consequently, the spectral tunability (96 nm) of the structures was significantly lower than that of simulated ideal nanoantennas. These observations, attributed to the nanofabrication process, are related to imperfections in the geometry, added metal adhesion layer, and shape modifications, which are analyzed in this work. Our results provide important information for the design of dipole nanoantennas clarifying the role of the structural modifications on the resonance spectra, as supported by calculations.

  9. Comparative Analysis of the Macroscale Structural Connectivity in the Macaque and Human Brain

    PubMed Central

    Bezgin, Gleb; Uylings, Harry B. M.; Roebroeck, Alard; Stiers, Peter

    2014-01-01

    The macaque brain serves as a model for the human brain, but its suitability is challenged by unique human features, including connectivity reconfigurations, which emerged during primate evolution. We perform a quantitative comparative analysis of the whole brain macroscale structural connectivity of the two species. Our findings suggest that the human and macaque brain as a whole are similarly wired. A region-wise analysis reveals many interspecies similarities of connectivity patterns, but also lack thereof, primarily involving cingulate regions. We unravel a common structural backbone in both species involving a highly overlapping set of regions. This structural backbone, important for mediating information across the brain, seems to constitute a feature of the primate brain persevering evolution. Our findings illustrate novel evolutionary aspects at the macroscale connectivity level and offer a quantitative translational bridge between macaque and human research. PMID:24676052

  10. Comparative study of vibrations in submonolayer structures of potassium on Pt(111).

    PubMed

    Rusina, G G; Eremeev, S V; Borisova, S D; Chulkov, E V

    2012-03-14

    We present results of a comparative study of the vibrational spectrum and local density of phonon states in ordered p(2 x 2) and (√3 x √3)R30° structures formed by potassium atoms on the Pt(111) surface. The calculations were performed with tight-binding interatomic interaction potentials. It was found that the mode associated with vertical displacements of K adatoms has an energy of about 20 meV in both K structures. The strength and energy of this mode slightly decreases with increasing coverage. This result is in good agreement with available experimental data. As in time-resolved second harmonic generation measurements, we observed low frequency modes for both structures considered, which are caused by the interaction of potassium with the second layer of the substrate.

  11. Comparative study of vibrations in submonolayer structures of potassium on Pt(111)

    NASA Astrophysics Data System (ADS)

    Rusina, G. G.; Eremeev, S. V.; Borisova, S. D.; Chulkov, E. V.

    2012-03-01

    We present results of a comparative study of the vibrational spectrum and local density of phonon states in ordered p(2 × 2) and (\\sqrt{3}\\times \\sqrt{3}){R}30^{\\circ} structures formed by potassium atoms on the Pt(111) surface. The calculations were performed with tight-binding interatomic interaction potentials. It was found that the mode associated with vertical displacements of K adatoms has an energy of about 20 meV in both K structures. The strength and energy of this mode slightly decreases with increasing coverage. This result is in good agreement with available experimental data. As in time-resolved second harmonic generation measurements, we observed low frequency modes for both structures considered, which are caused by the interaction of potassium with the second layer of the substrate.

  12. Comparative 3D genome structure analysis of the fission and the budding yeast.

    PubMed

    Gong, Ke; Tjong, Harianto; Zhou, Xianghong Jasmine; Alber, Frank

    2015-01-01

    We studied the 3D structural organization of the fission yeast genome, which emerges from the tethering of heterochromatic regions in otherwise randomly configured chromosomes represented as flexible polymer chains in an nuclear environment. This model is sufficient to explain in a statistical manner many experimentally determined distinctive features of the fission yeast genome, including chromatin interaction patterns from Hi-C experiments and the co-locations of functionally related and co-expressed genes, such as genes expressed by Pol-III. Our findings demonstrate that some previously described structure-function correlations can be explained as a consequence of random chromatin collisions driven by a few geometric constraints (mainly due to centromere-SPB and telomere-NE tethering) combined with the specific gene locations in the chromosome sequence. We also performed a comparative analysis between the fission and budding yeast genome structures, for which we previously detected a similar organizing principle. However, due to the different chromosome sizes and numbers, substantial differences are observed in the 3D structural genome organization between the two species, most notably in the nuclear locations of orthologous genes, and the extent of nuclear territories for genes and chromosomes. However, despite those differences, remarkably, functional similarities are maintained, which is evident when comparing spatial clustering of functionally related genes in both yeasts. Functionally related genes show a similar spatial clustering behavior in both yeasts, even though their nuclear locations are largely different between the yeast species.

  13. Time-sequenced and spectrally filtered Rayleigh imaging of shock wave and boundary layer structure for inlet characterization

    NASA Technical Reports Server (NTRS)

    Forkey, Joseph; Cogne, Sandrine; Smits, Alexander; Bogdonoff, Seymour; Lempert, Walter R.; Miles, Richard B.

    1993-01-01

    Multiple pulsed Rayleigh imaging and filtered Rayleigh scattering are used to generate images of a complex boundary layer structure, shock wave/boundary layer interactions, and crossing shock waves. Time-sequenced Rayleigh images taken with a visible, double-pulsed laser system show the evolution of boundary layer structure of the internal flow in a generic cross-shock inlet. The images taken in the inlet give insight into 3D effects caused by the inlet geometry and may be used for modeling the complex flows.

  14. A spectral study of the mid-latitude sporadic E layer characteristic oscillations comparable to those of the tidal and the planetary waves

    NASA Astrophysics Data System (ADS)

    Pignalberi, A.; Pezzopane, M.; Zuccheretti, E.

    2015-01-01

    In this paper different spectral analyses are employed to investigate the tidal and planetary wave periodicities imprinted in the following two main characteristics of the sporadic E (Es) layer: the top frequency (ftEs) and the lowest virtual height (h‧Es). The study is based on ionograms recorded during the summertime of 2013, and precisely in June, July, August and September, by the Advanced Ionospheric Sounder by Istituto Nazionale di Geofisica e Vulcanologia (AIS-INGV) ionosondes installed at Rome (41.8°N, 12.5°E) and Gibilmanna (37.9°N, 14.0°E), Italy. It was confirmed that the diurnal and semidiurnal atmospheric tides play a fundamental role in the formation of the mid-latitude Es layers, acting through their vertical wind-shear forcing of the long-living metallic ions in the lower thermosphere, and at the same time it was found that the planetary atmospheric waves might affect the Es layers acting through their horizontal wind-shear forcing with periods close to the normal Rossby modes, that is 2, 5, 10 and 16 days. The wavelet analysis shows also that the ftEs and h‧Es tidal oscillations undergo a strong amplitude modulation with periods of several days and with important differences between the two parameters. This amplitude modulation, characterizing markedly the first thirty days of the ftEs spectrogram, suggests that Es layers are affected indirectly by planetary waves through their nonlinear interaction with the atmospheric tides at lower altitudes. This study wants to be a continuation of the Haldoupis et al. (2004) work in order to verify their results for the foEs characteristic and on the other hand to extend the study also to the h‧Es characteristic not yet shown so far. Anyhow, the study confirms that ionosonde data, especially those registered in summertime, represent a powerful tool for studying tidal and planetary waves properties and their climatology in the mesosphere-low-thermosphere region.

  15. A study of the H-bonded structures and infrared and Raman spectral analysis of carbohydrazide and thiocarbohydrazide

    NASA Astrophysics Data System (ADS)

    Badawi, Hassan M.; Förner, Wolfgang

    2013-04-01

    The complex conformational profile and the vibrational spectra of carbohydrazide (1,3-diaminourea) and thiocarbohydrazide were investigated by the DFT-B3LYP and ab initio MP2 and MP4(SDQ) levels of theory using the 6-311G** basis set. The planar syn-cis-anti-trans structure of the two molecules with Cs symmetry was predicted to have an imaginary frequency. The corresponding non-planar structure (C1 symmetry) was predicted to be the lowest energy structure and to have a positive real frequency as the real minima of the molecules. The stability of the non-planar structure agrees with the X-ray study of carbohydrazide where significant molecular distortions from planarity were reported for the lowest energy form as a result of strong intermolecular hydrogen bonding in the crystal. The vibrational wavenumbers of the lowest energy non-planar conformer of carbohydrazide and thiocarbohydrazide were computed at the B3LYP level and complete vibrational assignments were provided on the basis of the combined DFT-B3LYP results, normal coordinate calculations and experimental infrared and Raman data.

  16. Novel proteases from the genome of the carnivorous plant Drosera capensis: Structural prediction and comparative analysis.

    PubMed

    Butts, Carter T; Bierma, Jan C; Martin, Rachel W

    2016-10-01

    In his 1875 monograph on insectivorous plants, Darwin described the feeding reactions of Drosera flypaper traps and predicted that their secretions contained a "ferment" similar to mammalian pepsin, an aspartic protease. Here we report a high-quality draft genome sequence for the cape sundew, Drosera capensis, the first genome of a carnivorous plant from order Caryophyllales, which also includes the Venus flytrap (Dionaea) and the tropical pitcher plants (Nepenthes). This species was selected in part for its hardiness and ease of cultivation, making it an excellent model organism for further investigations of plant carnivory. Analysis of predicted protein sequences yields genes encoding proteases homologous to those found in other plants, some of which display sequence and structural features that suggest novel functionalities. Because the sequence similarity to proteins of known structure is in most cases too low for traditional homology modeling, 3D structures of representative proteases are predicted using comparative modeling with all-atom refinement. Although the overall folds and active residues for these proteins are conserved, we find structural and sequence differences consistent with a diversity of substrate recognition patterns. Finally, we predict differences in substrate specificities using in silico experiments, providing targets for structure/function studies of novel enzymes with biological and technological significance. Proteins 2016; 84:1517-1533. © 2016 Wiley Periodicals, Inc.

  17. Comparing the Topological and Electrical Structure of the North American Electric Power Infrastructure

    NASA Astrophysics Data System (ADS)

    Cotilla-Sanchez, Eduardo; Hines, Paul D. H.; Barrows, Clayton; Blumsack, Seth

    2012-12-01

    The topological (graph) structure of complex networks often provides valuable information about the performance and vulnerability of the network. However, there are multiple ways to represent a given network as a graph. Electric power transmission and distribution networks have a topological structure that is straightforward to represent and analyze as a graph. However, simple graph models neglect the comprehensive connections between components that result from Ohm's and Kirchhoff's laws. This paper describes the structure of the three North American electric power interconnections, from the perspective of both topological and electrical connectivity. We compare the simple topology of these networks with that of random (Erdos and Renyi, 1959), preferential-attachment (Barabasi and Albert, 1999) and small-world (Watts and Strogatz, 1998) networks of equivalent sizes and find that power grids differ substantially from these abstract models in degree distribution, clustering, diameter and assortativity, and thus conclude that these topological forms may be misleading as models of power systems. To study the electrical connectivity of power systems, we propose a new method for representing electrical structure using electrical distances rather than geographic connections. Comparisons of these two representations of the North American power networks reveal notable differences between the electrical and topological structure of electric power networks.

  18. Comparative evaluation of structured oil systems: Shellac oleogel, HPMC oleogel, and HIPE gel

    PubMed Central

    Patel, Ashok R; Dewettinck, Koen

    2015-01-01

    In lipid-based food products, fat crystals are used as building blocks for creating a crystalline network that can trap liquid oil into a 3D gel-like structure which in turn is responsible for the desirable mouth feel and texture properties of the food products. However, the recent ban on the use of trans-fat in the US, coupled with the increasing concerns about the negative health effects of saturated fat consumption, has resulted in an increased interest in the area of identifying alternative ways of structuring edible oils using non-fat-based building blocks. In this paper, we give a brief account of three alternative approaches where oil structuring was carried out using wax crystals (shellac), polymer strands (hydrophilic cellulose derivative), and emulsion droplets as structurants. These building blocks resulted in three different types of oleogels that showed distinct rheological properties and temperature functionalities. The three approaches are compared in terms of the preparation process (ease of processing), properties of the formed systems (microstructure, rheological gel strength, temperature response, effect of water incorporation, and thixotropic recovery), functionality, and associated limitations of the structured systems. The comparative evaluation is made such that the new researchers starting their work in the area of oil structuring can use this discussion as a general guideline. Practical applications Various aspects of oil binding for three different building blocks were studied in this work. The practical significance of this study includes (i) information on the preparation process and the concentrations of structuring agents required for efficient gelation and (ii) information on the behavior of oleogels to temperature, applied shear, and presence of water. This information can be very useful for selecting the type of structuring agents keeping the final applications in mind. For detailed information on the actual edible applications

  19. ModBase, a database of annotated comparative protein structure models and associated resources

    PubMed Central

    Pieper, Ursula; Webb, Benjamin M.; Dong, Guang Qiang; Schneidman-Duhovny, Dina; Fan, Hao; Kim, Seung Joong; Khuri, Natalia; Spill, Yannick G.; Weinkam, Patrick; Hammel, Michal; Tainer, John A.; Nilges, Michael; Sali, Andrej

    2014-01-01

    ModBase (http://salilab.org/modbase) is a database of annotated comparative protein structure models. The models are calculated by ModPipe, an automated modeling pipeline that relies primarily on Modeller for fold assignment, sequence-structure alignment, model building and model assessment (http://salilab.org/modeller/). ModBase currently contains almost 30 million reliable models for domains in 4.7 million unique protein sequences. ModBase allows users to compute or update comparative models on demand, through an interface to the ModWeb modeling server (http://salilab.org/modweb). ModBase models are also available through the Protein Model Portal (http://www.proteinmodelportal.org/). Recently developed associated resources include the AllosMod server for modeling ligand-induced protein dynamics (http://salilab.org/allosmod), the AllosMod-FoXS server for predicting a structural ensemble that fits an SAXS profile (http://salilab.org/allosmod-foxs), the FoXSDock server for protein–protein docking filtered by an SAXS profile (http://salilab.org/foxsdock), the SAXS Merge server for automatic merging of SAXS profiles (http://salilab.org/saxsmerge) and the Pose & Rank server for scoring protein–ligand complexes (http://salilab.org/poseandrank). In this update, we also highlight two applications of ModBase: a PSI:Biology initiative to maximize the structural coverage of the human alpha-helical transmembrane proteome and a determination of structural determinants of human immunodeficiency virus-1 protease specificity. PMID:24271400

  20. Drift paths of ions composing multiple-nose spectral structures near the inner edge of the plasma sheet

    NASA Astrophysics Data System (ADS)

    Ferradas, C. P.; Zhang, J.-C.; Spence, H. E.; Kistler, L. M.; Larsen, B. A.; Reeves, G.; Skoug, R.; Funsten, H.

    2016-11-01

    We present a case study of the H+, He+, and O+ multiple-nose structures observed by the Helium, Oxygen, Proton, and Electron instrument on board Van Allen Probe A over one complete orbit on 28 September 2013. Nose structures are observed near the inner edge of the plasma sheet and constitute the signatures of ion drift in the highly dynamic environment of the inner magnetosphere. We find that the multiple noses are intrinsically associated with variations in the solar wind. Backward ion drift path tracings show new details of the drift trajectories of these ions; i.e., multiple noses are formed by ions with a short drift time from the assumed source location to the inner region and whose trajectories (1) encircle the Earth different number of times or (2) encircle the Earth equal number of times but with different drift time, before reaching the observation site.

  1. Investigation of the mica x-ray absorption near-edge structure spectral features at the Al K-edge

    NASA Astrophysics Data System (ADS)

    Wu, Ziyu; Marcelli, A.; Cibin, G.; Mottana, A.; Della Ventura, G.

    2003-10-01

    Near-edge features of Al x-ray absorption near-edge structure (XANES) spectra in aluminosilicate compounds with mixed coordination number are usually assigned to a fourfold coordinated site contribution followed by a sixfold coordinated site contribution that is displaced towards higher energy because of the increasing ligand nucleus potentials, neglecting possible contributions due to bond distance variations and local geometrical distortion. Here we present and discuss the Al K-edge XANES spectra of synthetic micas with either fourfold coordinated Al (phlogopite), or with sixfold coordinated Al (polylithionite), as well as with mixed coordination (preiswerkite). Multiple scattering simulations of XANES spectra demonstrate that octahedral contributions may overlap the tetrahedral ones so that the lower energy structures in mixed coordination compounds may be associated with the octahedral sites. This unexpected behaviour can be described as due to the effect of a significant reduction of the ligand field strength (i.e. large local distortion and Al-O bond distances).

  2. Spectral and polarization properties of a ‘cholesteric liquid crystal—phase plate—metal’ structure

    NASA Astrophysics Data System (ADS)

    Vetrov, S. Ya; Pyatnov, M. V.; Timofeev, I. V.

    2016-01-01

    We investigate the localized surface modes in a structure consisting of the cholesteric liquid crystal layer, a phase plate, and a metal layer. These modes are analogous to the optical Tamm states. The nonreciprocal transmission of polarized light propagating in the forward and backward directions is established. It is demonstrated that the transmission spectrum can be controlled by external fields acting on the cholesteric liquid crystal and by varying the plane of polarization of the incident light.

  3. Exploration of new multivariate spectral calibration algorithms.

    SciTech Connect

    Van Benthem, Mark Hilary; Haaland, David Michael; Melgaard, David Kennett; Martin, Laura Elizabeth; Wehlburg, Christine Marie; Pell, Randy J.; Guenard, Robert D.

    2004-03-01

    A variety of multivariate calibration algorithms for quantitative spectral analyses were investigated and compared, and new algorithms were developed in the course of this Laboratory Directed Research and Development project. We were able to demonstrate the ability of the hybrid classical least squares/partial least squares (CLSIPLS) calibration algorithms to maintain calibrations in the presence of spectrometer drift and to transfer calibrations between spectrometers from the same or different manufacturers. These methods were found to be as good or better in prediction ability as the commonly used partial least squares (PLS) method. We also present the theory for an entirely new class of algorithms labeled augmented classical least squares (ACLS) methods. New factor selection methods are developed and described for the ACLS algorithms. These factor selection methods are demonstrated using near-infrared spectra collected from a system of dilute aqueous solutions. The ACLS algorithm is also shown to provide improved ease of use and better prediction ability than PLS when transferring calibrations between near-infrared calibrations from the same manufacturer. Finally, simulations incorporating either ideal or realistic errors in the spectra were used to compare the prediction abilities of the new ACLS algorithm with that of PLS. We found that in the presence of realistic errors with non-uniform spectral error variance across spectral channels or with spectral errors correlated between frequency channels, ACLS methods generally out-performed the more commonly used PLS method. These results demonstrate the need for realistic error structure in simulations when the prediction abilities of various algorithms are compared. The combination of equal or superior prediction ability and the ease of use of the ACLS algorithms make the new ACLS methods the preferred algorithms to use for multivariate spectral calibrations.

  4. Structural stability, C--N internal rotations and vibrational spectral analysis of non-planar phenylurea and phenylthiourea.

    PubMed

    Badawi, Hassan M

    2009-04-01

    The structural stability and C-N internal rotations of phenylurea and phenylthiourea were investigated by DFT-B3LYP and ab initio MP2 and MP4//MP2 calculations with 6-311G** and/or 6-311+G** basis sets. The complex multirotor internal rotations in phenylurea and phenylthiourea were investigated at the B3LYP/6-311+G** level of theory from which several clear minima were predicted in the calculated potential energy scans of both molecules. For phenylurea two minima that correspond to non-planar- (CNCC dihedral angle of about 45 degrees ) cis (CNCO dihedral angle is near 0 degrees ) and trans (CNCO dihedral angle is near 180 degrees ) structures were predicted to have real frequency. For phenylthiourea only the non-planar-trans structure was predicted to be the low energy minimum for the molecule. The vibrational frequencies of the lowest energy non-planar-trans conformer of each of the two molecules were computed at the B3LYP level and tentative vibrational assignments were provided on the basis of normal coordinate analysis and experimental infrared and Raman data.

  5. Structural stability, C-N internal rotations and vibrational spectral analysis of non-planar phenylurea and phenylthiourea

    NASA Astrophysics Data System (ADS)

    Badawi, Hassan M.

    2009-04-01

    The structural stability and C-N internal rotations of phenylurea and phenylthiourea were investigated by DFT-B3LYP and ab initio MP2 and MP4//MP2 calculations with 6-311G** and/or 6-311+G** basis sets. The complex multirotor internal rotations in phenylurea and phenylthiourea were investigated at the B3LYP/6-311+G** level of theory from which several clear minima were predicted in the calculated potential energy scans of both molecules. For phenylurea two minima that correspond to non-planar- (CNCC dihedral angle of about 45°) cis (CNCO dihedral angle is near 0°) and trans (CNCO dihedral angle is near 180°) structures were predicted to have real frequency. For phenylthiourea only the non- planar- trans structure was predicted to be the low energy minimum for the molecule. The vibrational frequencies of the lowest energy non-planar-trans conformer of each of the two molecules were computed at the B3LYP level and tentative vibrational assignments were provided on the basis of normal coordinate analysis and experimental infrared and Raman data.

  6. A new tetranuclear copper(II) Schiff base complex containing Cu 4O 4 cubane core: Structural and spectral characterizations

    NASA Astrophysics Data System (ADS)

    Shit, Shyamapada; Rosair, Georgina; Mitra, Samiran

    2011-04-01

    A new tetra-nuclear coordination complex [Cu 4(HL) 4] ( 1) containing Cu 4O 4 cubane core has been synthesized by using Schiff base ligand [(OH)C 6H 4CH dbnd N sbnd C(CH 3)(CH 2OH) 2] (H 3L), obtained by the 1:1 condensation of 2-amino-2-methyl-1,3-propanediol with salicylaldehyde and thoroughly characterized by micro-analytical, FT-IR, UV-Vis, thermal and room temperature magnetic susceptibility measurements. Structural characterization of the complex has been done by single crystal X-ray diffraction analysis. Structural elucidation reveals versatile coordination modes for two identical alkoxo oxygen atoms of the Schiff base ligand; one in its deprotonated form exhibits μ 3-bridging to bind three similar copper(II) centers whilst the protonated one remains as monodentate or non-coordinating. Structural analysis also shows that the Cu 4O 4 cubane core in 1 consists of four μ 3-alkoxo oxygen bridged copper(II) atoms giving an approximately cubic array of alternating oxygen atoms and copper(II) atoms where the metal centers display both distorted square pyramidal and distorted octahedral geometries.

  7. Solvation shell structure of cyclooctylpyranone in water solvent and its comparative structure, dynamics and dipole moment in HIV protease.

    PubMed

    Arul Murugan, N; Chandra Jha, Prakash; Agren, Hans

    2009-08-14

    We have investigated the solvation structure for cyclooctylpyranone (COP) in water solvent using force-field molecular dynamics (MD) and Car-Parrinello mixed quantum mechanics-molecular mechanics (CPMD) calculations. The MD calculations show that in water solvent COP can exist in two conformational states which differ with respect to the relative orientations of the three rings, namely phenyl, pyranone and cyclooctane. We report the existence of strong orientational preference for the water molecule in the first solvation shell and the orientational preference disappears for solvent molecules beyond the first solvation shell. In order to investigate the confinement effect on the structure, dynamics, charge distribution and dipole moment of COP, we have carried out MD and CPMD calculations for COP within HIV type-1 protease (PR). Interestingly, we do not see any conformational transitions for COP within the protein cavity and it remains as a single conformer. We do see a remarkable effect of confinement on few other torsional degrees of freedom such as gg to tg conformational shift for the propyl group of COP. However, the methyl group rotational dynamics remains similar in the water solvent and in the protein environment. Also, within the protein cavity, the COP molecule is more polarized when compared to water solvent. Static ab initio electronic structure calculations were performed on the COP molecule with varying torsional angle in order to investigate the angle dependence of the molecular volume and energy.

  8. An Analytic Comparison of Educational Systems: Overview of Purposes, Policies, Structures and Outcomes. Comparative Overview/Comparative Assessment.

    ERIC Educational Resources Information Center

    Hurn, Christopher J.; Burn, Barbara B.

    This comparative evaluation of the differing educational systems in North America, Europe, the USSR, and Japan examines the goals and values of these systems. It is pointed out that Americans value equality, practicality, and utility and that they are both individualistic and suspicious of government authority. Contrasts between these values and…

  9. Investigation of the quaternary structure of an ABC transporter in living cells using spectrally resolved resonance energy transfer

    NASA Astrophysics Data System (ADS)

    Singh, Deo Raj

    Forster resonance energy transfer (FRET) has become an important tool to study proteins inside living cells. It has been used to explore membrane protein folding and dynamics, determine stoichiometry and geometry of protein complexes, and measure the distance between two molecules. In this dissertation, we use a method based on FRET and optical micro-spectroscopy (OptiMiS) technology, developed in our lab, to probe the structure of dynamic (as opposed to static) protein complexes in living cells. We use this method to determine the association stoichiometry and quaternary structure of an ABC transporter in living cells. Specifically, the transporter we investigate originates from the pathogen Pseudomonas aeruginosa, which is a Gram-negative bacterium with several virulence factors, lipopolysaccharides being one of them. This pathogen coexpresses two unique forms of lipopolysaccharides on its surface, the A- and B-bands. The A-band polysaccharides, synthesized in the cytoplasm, are translocated into the periplasm through an ATP-binding-cassette (ABC) transporter consisting of a transmembranar protein, Wzm, and a nucleotide-binding protein, Wzt. In P. aeruginosa, all of the biochemical studies of A-band LPS are concentrated on the stages of the synthesis and ligation of polysaccharides (PSs), leaving the export stage involving ABC transporter unexplored. The mode of PS export through ABC transporters is still unknown. This difficulty is due to the lack of information about sub-unit composition and structure of this bi-component ABC transporter. Using the FRET-OptiMiS combination method developed by our lab, we found that Wzt forms a rhombus-shaped homo-tetramer which becomes a square upon co-expression with Wzm, and that Wzm forms a square-shaped homo-tetramer both in the presence and absence of Wzt. Based on these results, we propose a structural model for the double-tetramer complex formed by the bi-component ABC transporter in living cells. An understanding of the

  10. Comparability of a Three-Dimensional Structure in Biopharmaceuticals Using Spectroscopic Methods

    PubMed Central

    Abad-Javier, Mario E.; Romero-Díaz, Alexis J.; Villaseñor-Ortega, Francisco; Pérez, Néstor O.; Flores-Ortiz, Luis F.

    2014-01-01

    Protein structure depends on weak interactions and covalent bonds, like disulfide bridges, established according to the environmental conditions. Here, we present the validation of two spectroscopic methodologies for the measurement of free and unoxidized thiols, as an attribute of structural integrity, using 5,5′-dithionitrobenzoic acid (DTNB) and DyLight Maleimide (DLM) as derivatizing agents. These methods were used to compare Rituximab and Etanercept products from different manufacturers. Physicochemical comparability was demonstrated for Rituximab products as DTNB showed no statistical differences under native, denaturing, and denaturing-reducing conditions, with Student's t-test P values of 0.6233, 0.4022, and 0.1475, respectively. While for Etanercept products no statistical differences were observed under native (P = 0.0758) and denaturing conditions (P = 0.2450), denaturing-reducing conditions revealed cysteine contents of 98% and 101%, towards the theoretical value of 58, for the evaluated products from different Etanercept manufacturers. DLM supported equality between Rituximab products under native (P = 0.7499) and denaturing conditions (P = 0.8027), but showed statistical differences among Etanercept products under native conditions (P < 0.001). DLM suggested that Infinitam has fewer exposed thiols than Enbrel, although DTNB method, circular dichroism (CD), fluorescence (TCSPC), and activity (TNFα neutralization) showed no differences. Overall, this data revealed the capabilities and drawbacks of each thiol quantification technique and their correlation with protein structure. PMID:24963443

  11. Comparability of a three-dimensional structure in biopharmaceuticals using spectroscopic methods.

    PubMed

    Pérez Medina Martínez, Víctor; Abad-Javier, Mario E; Romero-Díaz, Alexis J; Villaseñor-Ortega, Francisco; Pérez, Néstor O; Flores-Ortiz, Luis F; Medina-Rivero, Emilio

    2014-01-01

    Protein structure depends on weak interactions and covalent bonds, like disulfide bridges, established according to the environmental conditions. Here, we present the validation of two spectroscopic methodologies for the measurement of free and unoxidized thiols, as an attribute of structural integrity, using 5,5'-dithionitrobenzoic acid (DTNB) and DyLight Maleimide (DLM) as derivatizing agents. These methods were used to compare Rituximab and Etanercept products from different manufacturers. Physicochemical comparability was demonstrated for Rituximab products as DTNB showed no statistical differences under native, denaturing, and denaturing-reducing conditions, with Student's t-test P values of 0.6233, 0.4022, and 0.1475, respectively. While for Etanercept products no statistical differences were observed under native (P = 0.0758) and denaturing conditions (P = 0.2450), denaturing-reducing conditions revealed cysteine contents of 98% and 101%, towards the theoretical value of 58, for the evaluated products from different Etanercept manufacturers. DLM supported equality between Rituximab products under native (P = 0.7499) and denaturing conditions (P = 0.8027), but showed statistical differences among Etanercept products under native conditions (P < 0.001). DLM suggested that Infinitam has fewer exposed thiols than Enbrel, although DTNB method, circular dichroism (CD), fluorescence (TCSPC), and activity (TNF α neutralization) showed no differences. Overall, this data revealed the capabilities and drawbacks of each thiol quantification technique and their correlation with protein structure.

  12. Large Spectral Library Problem

    SciTech Connect

    Chilton, Lawrence K.; Walsh, Stephen J.

    2008-10-03

    Hyperspectral imaging produces a spectrum or vector at each image pixel. These spectra can be used to identify materials present in the image. In some cases, spectral libraries representing atmospheric chemicals or ground materials are available. The challenge is to determine if any of the library chemicals or materials exist in the hyperspectral image. The number of spectra in these libraries can be very large, far exceeding the number of spectral channels collected in the ¯eld. Suppose an image pixel contains a mixture of p spectra from the library. Is it possible to uniquely identify these p spectra? We address this question in this paper and refer to it as the Large Spectral Library (LSL) problem. We show how to determine if unique identi¯cation is possible for any given library. We also show that if p is small compared to the number of spectral channels, it is very likely that unique identi¯cation is possible. We show that unique identi¯cation becomes less likely as p increases.

  13. Application of spectral analysis techniques in the intercomparison of aerosol data: Part III. Using combined PCA to compare spatiotemporal variability of MODIS, MISR, and OMI aerosol optical depth

    NASA Astrophysics Data System (ADS)

    Li, Jing; Carlson, Barbara E.; Lacis, Andrew A.

    2014-04-01

    Satellite measurements of global aerosol properties are very useful in constraining aerosol parameterization in climate models. The reliability of different data sets in representing global and regional aerosol variability becomes an essential question. In this study, we present the results of a comparison using combined principal component analysis (CPCA), applied to monthly mean, mapped (Level 3) aerosol optical depth (AOD) product from Moderate Resolution Imaging Spectroradiometer (MODIS), Multiangle Imaging Spectroradiometer (MISR), and Ozone Monitoring Instrument (OMI). This technique effectively finds the common space-time variability in the multiple data sets by decomposing the combined AOD field. The results suggest that all of the sensors capture the globally important aerosol regimes, including dust, biomass burning, pollution, and mixed aerosol types. Nonetheless, differences are also noted. Specifically, compared with MISR and OMI, MODIS variability is significantly higher over South America, India, and the Sahel. MODIS deep blue AOD has a lower seasonal variability in North Africa, accompanied by a decreasing trend that is not found in either MISR or OMI AOD data. The narrow swath of MISR results in an underestimation of dust variability over the Taklamakan Desert. The MISR AOD data also exhibit overall lower variability in South America and the Sahel. OMI does not capture the Russian wild fire in 2010 nor the phase shift in biomass burning over East South America compared to Central South America, likely due to cloud contamination and the OMI row anomaly. OMI also indicates a much stronger (boreal) winter peak in South Africa compared with MODIS and MISR.

  14. Application of Spectral Analysis Techniques in the Intercomparison of Aerosol Data: Part III. Using Combined PCA to Compare Spatiotemporal Variability of MODIS, MISR and OMI Aerosol Optical Depth

    NASA Technical Reports Server (NTRS)

    Li, Jing; Carlson, Barbara E.; Lacis, Andrew A.

    2014-01-01

    Satellite measurements of global aerosol properties are very useful in constraining aerosol parameterization in climate models. The reliability of different data sets in representing global and regional aerosol variability becomes an essential question. In this study, we present the results of a comparison using combined principal component analysis (CPCA), applied to monthly mean, mapped (Level 3) aerosol optical depth (AOD) product from Moderate Resolution Imaging Spectroradiometer (MODIS), Multiangle Imaging Spectroradiometer (MISR), and Ozone Monitoring Instrument (OMI). This technique effectively finds the common space-time variability in the multiple data sets by decomposing the combined AOD field. The results suggest that all of the sensors capture the globally important aerosol regimes, including dust, biomass burning, pollution, and mixed aerosol types. Nonetheless, differences are also noted. Specifically, compared with MISR and OMI, MODIS variability is significantly higher over South America, India, and the Sahel. MODIS deep blue AOD has a lower seasonal variability in North Africa, accompanied by a decreasing trend that is not found in either MISR or OMI AOD data. The narrow swath of MISR results in an underestimation of dust variability over the Taklamakan Desert. The MISR AOD data also exhibit overall lower variability in South America and the Sahel. OMI does not capture the Russian wild fire in 2010 nor the phase shift in biomass burning over East South America compared to Central South America, likely due to cloud contamination and the OMI row anomaly. OMI also indicates a much stronger (boreal) winter peak in South Africa compared with MODIS and MISR.

  15. Comparative Study of Anterior Eye Segment Measurements with Spectral Swept-Source and Time-Domain Optical Coherence Tomography in Eyes with Corneal Dystrophies

    PubMed Central

    Nowinska, Anna K.; Teper, Sławomir J.; Janiszewska, Dominika A.; Lyssek-Boron, Anita; Dobrowolski, Dariusz; Koprowski, Robert; Wylegala, Edward

    2015-01-01

    Purpose. To compare anterior eye segment measurements and morphology obtained with two optical coherence tomography systems (TD OCT, SS OCT) in eyes with corneal dystrophies (CDs). Methods. Fifty healthy volunteers (50 eyes) and 54 patients (96 eyes) diagnosed with CD (epithelial basement membrane dystrophy, EBMD = 12 eyes; Thiel-Behnke CD = 6 eyes; lattice CD TGFBI type = 15 eyes; granular CD type 1 = 7 eyes, granular CD type 2 = 2 eyes; macular CD = 23 eyes; and Fuchs endothelial CD = 31 eyes) were recruited for the study. Automated and manual central corneal thickness (aCCT, mCCT), anterior chamber depth (ACD), and nasal and temporal trabecular iris angle (nTIA, tTIA) were measured and compared with Bland-Altman plots. Results. Good agreement between the TD and SS OCT measurements was demonstrated for mCCT and aCCT in normal individuals and for mCCT in the CDs group. The ACD, nTIA, and tTIA measurements differed significantly in both groups. TBCD, LCD, and FECD caused increased CCT. MCD caused significant corneal thinning. FECD affected all analyzed parameters. Conclusions. Better agreement between SS OCT and TD OCT measurements was demonstrated in normal individuals compared to the CDs group. OCT provides comprehensive corneal deposits analysis and demonstrates the association of CD with CCT, ACD, and TIA measurements. PMID:26457303

  16. Structural geology investigation in the republics of Dahomey and Togoland, Africa, using ERTS-1 multi-spectral images

    NASA Technical Reports Server (NTRS)

    Weecksteen, G. (Principal Investigator)

    1974-01-01

    The author has identified the following significant results. Recent geological studies in the Republics of Dahomey and Togoland put in light a new chronology and propose a schema indicating that the structural geology of this region is very complicated. The new observations made possible by the ERTS images concern the main orientations, the folded units, and the lithology. The correlation between different types of laterite and the petrology of the basement seems possible, and is the most significant result of this investigation but unfortunately conducted with poor quality images because of atmospheric haze.

  17. Four imidazolium iodocuprates based on anion-π and π-π interactions: Structural and spectral modulation

    NASA Astrophysics Data System (ADS)

    Liu, Fang; Hao, Pengfei; Yu, Tanlai; Guan, Qi; Fu, Yunlong

    2016-09-01

    Four imidazolium iodocuprates, [(1,3-dimethylimidazole)(Cu2I3)]n (1), [(1,2,3-trimethylimidazole)(Cu2I3)]n (2), [(1,3-dimethylimidazole)(Cu3I5)]n (3) and [(1,3-dimethylbenzimidazole)(CuI2)]n (4) have been solvothermally synthesized and optically characterized. Results exhibit that cationic spatial orientation, anion-π and π-π interactions are beneficial to structural diversity and band gap modulation of iodocuprate hybrids. The UV-vis diffuse reflectance spectra show that compounds 1-4 are potential semiconductor materials.

  18. Growth, structural, spectral, optical, and thermal studies on amino acid based new NLO single crystal: L-phenylalanine-4-nitrophenol

    NASA Astrophysics Data System (ADS)

    Prakash, M.; Lydia Caroline, M.; Geetha, D.

    2013-05-01

    A new organic nonlinear optical single crystal, L-phenylalanine-4-nitrophenol (LPAPN) belonging to the amino acid group has been successfully grown by slow evaporation technique. The lattice parameters of the grown crystal have been determined by X-ray diffraction studies. FT-IR spectrum was recorded to identify the presence of functional group and molecular structure was confirmed by NMR spectrum. Thermal strength of the grown crystal has been studied using TG-DTA analyses. The grown crystals were found to be transparent in the entire visible region. The existence of second harmonic generation signals was observed using Nd:YAG laser with fundamental wavelength of 1064 nm.

  19. Growth, structural, spectral, optical, and thermal studies on amino acid based new NLO single crystal: L-phenylalanine-4-nitrophenol.

    PubMed

    Prakash, M; Lydia Caroline, M; Geetha, D

    2013-05-01

    A new organic nonlinear optical single crystal, L-phenylalanine-4-nitrophenol (LPAPN) belonging to the amino acid group has been successfully grown by slow evaporation technique. The lattice parameters of the grown crystal have been determined by X-ray diffraction studies. FT-IR spectrum was recorded to identify the presence of functional group and molecular structure was confirmed by NMR spectrum. Thermal strength of the grown crystal has been studied using TG-DTA analyses. The grown crystals were found to be transparent in the entire visible region. The existence of second harmonic generation signals was observed using Nd:YAG laser with fundamental wavelength of 1064 nm.

  20. Synthesis, spectral and structural studies of alkyl 2-(3-alkyl-2,6-diarylpiperidin-4-ylidene)hydrazinecarboxylate derivatives: Crystal and molecular structure of methyl 2-(3-methyl-2,6-diphenylpiperidin-4-ylidene)hydrazinecarboxylate

    NASA Astrophysics Data System (ADS)

    Udhaya Kumar, C.; Sethukumar, A.; Velayutham Pillai, M.; Arul Prakasam, B.; Ramalingan, C.; Vidhyasagar, T.

    2016-05-01

    An efficient synthetic route with good overall yields to synthesize alkyl 2-(3-alkyl-2,6-diarylpiperidin-4-ylidene)hydrazinecarboxylates (7-14) is reported. All the synthesized compounds were characterized by their analytical and spectral (IR, 1H, 13C and 2D NMR) data. Single crystal X-ray structural analysis of compound 7, evidences that the configuration about Cdbnd N double bond is syn to C5 carbon (E-form) and exists in normal chair conformation with equatorial orientations of all the substituents.

  1. Structural violence in long-term, residential care for older people: comparing Canada and Scandinavia.

    PubMed

    Banerjee, Albert; Daly, Tamara; Armstrong, Pat; Szebehely, Marta; Armstrong, Hugh; Lafrance, Stirling

    2012-02-01

    Canadian frontline careworkers are six times more likely to experience daily physical violence than their Scandinavian counterparts. This paper draws on a comparative survey of residential careworkers serving older people across three Canadian provinces (Manitoba, Nova Scotia, Ontario) and four countries that follow a Scandinavian model of social care (Denmark, Finland, Norway, Sweden) conducted between 2005 and 2006. Ninety percent of Canadian frontline careworkers experienced physical violence from residents or their relatives and 43 percent reported physical violence on a daily basis. Canadian focus groups conducted in 2007 reveal violence was often normalized as an inevitable part of elder-care. We use the concept of "structural violence" (Galtung, 1969) to raise questions about the role that systemic and organizational factors play in setting the context for violence. Structural violence refers to indirect forms of violence that are built into social structures and that prevent people from meeting their basic needs or fulfilling their potential. We applied the concept to long-term residential care and found that the poor quality of the working conditions and inadequate levels of support experienced by Canadian careworkers constitute a form of structural violence. Working conditions are detrimental to careworker's physical and mental health, and prevent careworkers from providing the quality of care they are capable of providing and understand to be part of their job. These conditions may also contribute to the physical violence workers experience, and further investigation is warranted.

  2. Comparative metabolomics and structural characterizations illuminate colibactin pathway-dependent small molecules.

    PubMed

    Vizcaino, Maria I; Engel, Philipp; Trautman, Eric; Crawford, Jason M

    2014-07-02

    The gene cluster responsible for synthesis of the unknown molecule "colibactin" has been identified in mutualistic and pathogenic Escherichia coli. The pathway endows its producer with a long-term persistence phenotype in the human bowel, a probiotic activity used in the treatment of ulcerative colitis, and a carcinogenic activity under host inflammatory conditions. To date, functional small molecules from this pathway have not been reported. Here we implemented a comparative metabolomics and targeted structural network analyses approach to identify a catalog of small molecules dependent on the colibactin pathway from the meningitis isolate E. coli IHE3034 and the probiotic E. coli Nissle 1917. The structures of 10 pathway-dependent small molecules are proposed based on structural characterizations and network relationships. The network will provide a roadmap for the structural and functional elucidation of a variety of other small molecules encoded by the pathway. From the characterized small molecule set, in vitro bacterial growth inhibitory and mammalian CNS receptor antagonist activities are presented.

  3. [Casting faults and structural studies on bonded alloys comparing centrifugal castings and vacuum pressure castings].

    PubMed

    Fuchs, P; Küfmann, W

    1978-07-01

    The casting processes in use today such as centrifugal casting and vacuum pressure casting were compared with one another. An effort was made to answer the question whether the occurrence of shrink cavities and the mean diameter of the grain of the alloy is dependent on the method of casting. 80 crowns were made by both processes from the baked alloys Degudent Universal, Degudent N and the trial alloy 4437 of the firm Degusa. Slice sections were examined for macro and micro-porosity and the structural appearance was evaluated by linear analysis. Statistical analysis showed that casting faults and casting structure is independent of the method used and their causes must be found in the conditions of casting and the composition of the alloy.

  4. Spectral, structural and quantum chemical computational and dissociation constant studies of a novel azo-enamine tautomer

    NASA Astrophysics Data System (ADS)

    Gözel, Asuman; Kose, Muhammet; Karakaş, Duran; Atabey, Hasan; McKee, Vickie; Kurtoglu, Mukerrem

    2014-09-01

    We report here the synthesis of (6Z)-4-[(E)-(4-ethylphenyl)diazenyl]-6-{[(2-hydroxy-5-methylphenyl)amino]methylidene}cyclohexa-2,4-dien-1-one by the condensation reaction between 2-amino-4-methylphenol and 5-[(E)-(4-ethylphenyl)diazenyl]-2-hydroxybenzaldehyde in equimolar ratio in MeOH and characterized by elemental analyses, infrared, electronic, mass,1H and 13C NMR spectroscopy. Molecular structure of the azo-enamine dye was also determined by single crystal X-ray diffraction technique. X-ray investigation of the dye showed that azo-enamine tautomer is favoured in the solid state. There is an intramolecular hydrogen bonding (N3-H···O1) in the molecule forming a S(6) graph set motif. Additionally, there is an intermolecular O2-H···O1 hydrogen bonding in the structure. The same intermolecular hydrogen bonding contacts are extended between the other symmetry-related molecules in their respective planes to form a 1D hydrogen bond chain. Self-isomerisation via intramolecular proton transfer was investigated by UV-Vis. spectra and theoretical calculations. Effects of polarity and temperature on UV-Vis. spectra were examined in detail. Moreover, acid dissociation properties of the polydentate compound was investigated at 25 ± 0.1 °C.

  5. Multiscale comparative spectral analysis of satellite total solar irradiance measurements from 2003 to 2013 reveals a planetary modulation of solar activity and its nonlinear dependence on the 11 yr solar cycle

    NASA Astrophysics Data System (ADS)

    Scafetta, N.; Willson, R. C.

    2013-11-01

    Herein we adopt a multiscale dynamical spectral analysis technique to compare and study the dynamical evolution of the harmonic components of the overlapping ACRIMSAT/ACRIM3 (Active Cavity Radiometer Irradiance Monitor Satellite/Active Cavity Radiometer Irradiance Monitor 3), SOHO/VIRGO (Solar and Heliopheric Observatory/Variability of solar Irradiance and Gravity Oscillations), and SORCE/TIM (Solar Radiation and Climate Experiment/Total Irradiance Monitor) total solar irradiance (TSI) records during 2003.15 to 2013.16 in solar cycles 23 and 24. The three TSI time series present highly correlated patterns. Significant power spectral peaks are common to these records and are observed at the following periods: ~ 0.070 yr, ~ 0.097 yr, ~ 0.20 yr, ~ 0.25 yr, ~ 0.30-0.34 yr, and ~ 0.39 yr. Less certain spectral peaks occur at about 0.55 yr, 0.60-0.65 yr and 0.7-0.9 yr. Four main frequency periods at ~ 4.8 days (~ 0.068 yr), ~ 27.3 days (~ 0.075 yr), at ~ 34-35 days (~ 0.093-0.096 yr), and ~ 36-38 days (~ 0.099-0.104 yr) characterize the solar rotation cycle. The amplitude of these oscillations, in particular of those with periods larger than 0.5 yr, appears to be modulated by the ~ 11 yr solar cycle. Similar harmonics have been found in other solar indices. The observed periodicities are found highly coherent with the spring, orbital and synodic periods of Mercury, Venus, Earth and Jupiter. We conclude that solar activity is likely modulated by planetary gravitational and electromagnetic forces acting on the Sun. The strength of the Sun's response to planetary forcing depends nonlinearly on the state of internal solar dynamics; planetary-Sun coupling effects are enhanced during solar activity maxima and attenuated during minima.

  6. [Comparative analysis of the genetic structure of Red Polish cattle in Poland and the Ukraine].

    PubMed

    Oblap, R V; Zvezhkhovski, L; Ivanchenko, E V; Glazko, V I

    2002-01-01

    Comparative analysis of genetic structure of two groups of Red Polish cattle, which reproduce in Poland and Ukraine, was made. Six molecular-genetic markers (kappa-casein, beta-lactoglobulin, leptin, myostatin, growth hormone, and pituitary-specific transcription factor Pit-I) were tested by PCR-RFLP. No significant differences between the considered intrabreed groups were found. High frequency of some alleles (Csn kappa B, Blg B, and Gh L) related to the important productivity traits were observed. The rare alleles in some genes were revealed. The obtained results are evidence of the unique characteristics of the investigated breed.

  7. A comparative study of the inner ear structures of artiodactyls and early cetaceans

    SciTech Connect

    Klingshirn, M.A.; Luo, Z.

    1994-12-31

    It has been suggested that the order Cetacea (whales and porpoises) are closely related to artiodactyls, even-hoofed ungulate mammals such as the pig and cow. Paleontological and molecular data strongly supports this concept of phylogenetic relationships. In a study of DNA sequences of two mitochondrial ribosomal gene segments of cetaceans, the artiodactyls were found to be closest related to Cetaceans. These well accepted studies on the phylogenetic affinities of artiodactyls and cetaceans cause us to conduct a comparative study of the bony structure of the inner ear of these two taxa.

  8. Comparing two iteration algorithms of Broyden electron density mixing through an atomic electronic structure computation

    NASA Astrophysics Data System (ADS)

    Man-Hong, Zhang

    2016-05-01

    By performing the electronic structure computation of a Si atom, we compare two iteration algorithms of Broyden electron density mixing in the literature. One was proposed by Johnson and implemented in the well-known VASP code. The other was given by Eyert. We solve the Kohn-Sham equation by using a conventional outward/inward integration of the differential equation and then connect two parts of solutions at the classical turning points, which is different from the method of the matrix eigenvalue solution as used in the VASP code. Compared to Johnson’s algorithm, the one proposed by Eyert needs fewer total iteration numbers. Project supported by the National Natural Science Foundation of China (Grant No. 61176080).

  9. Comparing Treatment Policies with Assistance from the Structural Nested Mean Model

    PubMed Central

    Lu, Xi; Lynch, Kevin G.; Oslin, David W.; Murphy, Susan

    2015-01-01

    Summary Treatment policies, also known as dynamic treatment regimes, are sequences of decision rules that link the observed patient history with treatment recommendations. Multiple, plausible, treatment policies are frequently constructed by researchers using expert opinion, theories and reviews of the literature. Often these different policies represent competing approaches to managing an illness. Here we develop an “assisted estimator” that can be used to compare the mean outcome of competing treatment policies. The term “assisted” refers to the fact estimators from the Structural Nested Mean Model, a parametric model for the causal effect of treatment at each time point, are used in the process of estimating the mean outcome. This work is motivated by our work on comparing the mean outcome of two competing treatment policies using data from the ExTENd study in alcohol dependence. PMID:26363892

  10. Metamorphic distributed Bragg reflectors for the 1440–1600 nm spectral range: Epitaxy, formation, and regrowth of mesa structures

    SciTech Connect

    Egorov, A. Yu. Karachinsky, L. Ya.; Novikov, I. I.; Babichev, A. V.; Berezovskaya, T. N.; Nevedomskiy, V. N.

    2015-10-15

    It is shown that metamorphic In{sub 0.3}Ga{sub 0.7}As/In{sub 0.3}Al{sub 0.7}As distributed Bragg reflectors (DBRs) with a reflection band at 1440–1600 nm and a reflectance of no less than 0.999 can be fabricated by molecular beam epitaxy (MBE) on a GaAs substrate. It is demonstrated that mesa structures formed from metamorphic DBRs on a GaAs substrate can be regrown by MBE and microcavities can be locally formed in two separate epitaxial processes. The results obtained can find wide application in the fabrication of vertical-cavity surface-emitting lasers (VCSELs) with a buried tunnel junction.

  11. Spectral and structural properties of 2D network complex [Ni(4,4'-bipyridine) 2(NCS) 2] n

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Jianmin, L.; Nishiura, M.; Imamoto, T.

    2000-02-01

    The complex [Ni(4,4'-bipyridine) 2(NCS) 2] n, in which nickel atoms are linked by two different Ni-4,4'-bpy-Ni assemblies to form two-dimensional distorted square net structure and the most effective packing of layers, has been isolated and structurally characterized. It represents the first example of Ni(II)-4,4'-bpy complex possesses 2D network. Crystal data for I: Fw=487.23, a=12.156(3), b=11.38(2), c=16.646(8) Å, β=100.43(3), V=2265(1) Å3, Z=4, space group=C2/c, T=298 K, λ((Mo-K α)=0.71070 Å, ρ calc=1.429 g cm -3, μ=10.62 cm-1, F(000)=1000, R=0.054, Rw=0.086, GOF=3.98. The UV-VIS absorption spectrum of the title complex is also reported and explained perfectly by the scaling radial theory which proposed by us. The strong and broad absorption bands occurred at 10433, 16830, 26556 cm -1, and they are assigned as d-d transitions of Ni(II) ion in octahedral field: 3A2g→ 3T2ga,b+ 3T2gc; 3A2g→ 3T1gz+ 3T1gy,x; 3A2g→ 3T1gz+ 3T1gy,x. The calculated results of the d-d transition energy levels agree well with the experimental values.

  12. Comparative Analysis of Data Structures for Storing Massive Tins in a Dbms

    NASA Astrophysics Data System (ADS)

    Kumar, K.; Ledoux, H.; Stoter, J.

    2016-06-01

    Point cloud data are an important source for 3D geoinformation. Modern day 3D data acquisition and processing techniques such as airborne laser scanning and multi-beam echosounding generate billions of 3D points for simply an area of few square kilometers. With the size of the point clouds exceeding the billion mark for even a small area, there is a need for their efficient storage and management. These point clouds are sometimes associated with attributes and constraints as well. Storing billions of 3D points is currently possible which is confirmed by the initial implementations in Oracle Spatial SDO PC and the PostgreSQL Point Cloud extension. But to be able to analyse and extract useful information from point clouds, we need more than just points i.e. we require the surface defined by these points in space. There are different ways to represent surfaces in GIS including grids, TINs, boundary representations, etc. In this study, we investigate the database solutions for the storage and management of massive TINs. The classical (face and edge based) and compact (star based) data structures are discussed at length with reference to their structure, advantages and limitations in handling massive triangulations and are compared with the current solution of PostGIS Simple Feature. The main test dataset is the TIN generated from third national elevation model of the Netherlands (AHN3) with a point density of over 10 points/m2. PostgreSQL/PostGIS DBMS is used for storing the generated TIN. The data structures are tested with the generated TIN models to account for their geometry, topology, storage, indexing, and loading time in a database. Our study is useful in identifying what are the limitations of the existing data structures for storing massive TINs and what is required to optimise these structures for managing massive triangulations in a database.

  13. Structural and compositional changes in erythrocyte membrane of obese compared to normal-weight adolescents.

    PubMed

    Perona, Javier S; González-Jiménez, Emilio; Aguilar-Cordero, María J; Sureda, Antonio; Barceló, Francisca

    2013-12-01

    Unhealthy dietary habits are key determinants of obesity in adolescents. Assuming that dietary fat profile influences membrane lipid composition, the aim of this study was to analyze structural changes in the erythrocyte membrane of obese compared to normal-weight adolescents. The study was conducted in a group of 11 obese and 11 normal-weight adolescent subjects. The lipid profile, lipid peroxidation and acetylcholinesterase enzyme (AChE) activity were analyzed by conventional methods. The structural properties of reconstituted erythrocyte membrane were characterized by X-ray diffraction. Erythrocyte membrane from obese adolescents had a lipid profile characterized by a higher cholesterol/phospholipid ratio, an increase in saturated fatty acid and a decrease in monounsaturated and n-6 polyunsaturated fatty acid concentrations. Differences in lipid content were associated with changes in the structural properties of reconstituted membranes and the oxidative damage of erythrocyte membrane. The lower oxidative level shown in the obese group (0.15 ± 0.04 vs. 0.20 ± 0.06 nmol/mg for conjugated diene concentrations and 2.43 ± 0.25 vs. 2.83 ± 0.31 nmol/mg protein for malondialdehyde levels) was related to a lower unsaturation index. These changes in membrane structural properties were accompanied by a lower AChE activity (1.64 ± 0.13 vs. 1.91 ± 0.24 nmol AChE/[min mg protein]) in the obese group. The consequences of unhealthy dietary habits in adolescents are reflected in the membrane structural properties and may influence membrane-associated protein activities and functions.

  14. Chiral solitons in the spectral quark model

    NASA Astrophysics Data System (ADS)

    Arriola, Enrique Ruiz; Broniowski, Wojciech; Golli, Bojan

    2007-07-01

    Chiral solitons with baryon number one are investigated in the spectral quark model. In this model the quark propagator is a superposition of complex-mass propagators weighted with a suitable spectral function. This technique is a method of regularizing the effective quark theory in a way preserving many desired features crucial in analysis of solitons. We review the model in the vacuum sector, stressing the feature of the absence of poles in the quark propagator. We also investigate in detail the analytic structure of meson two-point functions. We provide an appropriate prescription for constructing valence states in the spectral approach. The valence state in the baryonic soliton is identified with a saddle point of the Dirac eigenvalue treated as a function of the spectral mass. Because of this feature the valence quarks never become unbound nor dive into the negative spectrum, hence providing stable solitons as absolute minima of the action. This is a manifestation of the absence of poles in the quark propagator. Self-consistent mean-field hedgehog solutions are found numerically and some of their properties are determined and compared to previous chiral soliton models. Our analysis constitutes an involved example of a treatment of a relativistic complex-mass system.

  15. [Research on Spectral Polarization Imaging System Based on Static Modulation].

    PubMed

    Zhao, Hai-bo; Li, Huan; Lin, Xu-ling; Wang, Zheng

    2015-04-01

    The main disadvantages of traditional spectral polarization imaging system are: complex structure, with moving parts, low throughput. A novel method of spectral polarization imaging system is discussed, which is based on static polarization intensity modulation combined with Savart polariscope interference imaging. The imaging system can obtain real-time information of spectral and four Stokes polarization messages. Compared with the conventional methods, the advantages of the imaging system are compactness, low mass and no moving parts, no electrical control, no slit and big throughput. The system structure and the basic theory are introduced. The experimental system is established in the laboratory. The experimental system consists of reimaging optics, polarization intensity module, interference imaging module, and CCD data collecting and processing module. The spectral range is visible and near-infrared (480-950 nm). The white board and the plane toy are imaged by using the experimental system. The ability of obtaining spectral polarization imaging information is verified. The calibration system of static polarization modulation is set up. The statistical error of polarization degree detection is less than 5%. The validity and feasibility of the basic principle is proved by the experimental result. The spectral polarization data captured by the system can be applied to object identification, object classification and remote sensing detection.

  16. Enhanced Spectral Anisotropies Near the Proton-Cyclotron Scale: Possible Two-Component Structure in Hall-FLR MHD Turbulence Simulations

    NASA Technical Reports Server (NTRS)

    Ghosh, Sanjoy; Goldstein, Melvyn L.

    2011-01-01

    Recent analysis of the magnetic correlation function of solar wind fluctuations at 1 AU suggests the existence of two-component structure near the proton-cyclotron scale. Here we use two-and-one-half dimensional and three-dimensional compressible MHD models to look for two-component structure adjacent the proton-cyclotron scale. Our MHD system incorporates both Hall and Finite Larmor Radius (FLR) terms. We find that strong spectral anisotropies appear adjacent the proton-cyclotron scales depending on selections of initial condition and plasma beta. These anisotropies are enhancements on top of related anisotropies that appear in standard MHD turbulence in the presence of a mean magnetic field and are suggestive of one turbulence component along the inertial scales and another component adjacent the dissipative scales. We compute the relative strengths of linear and nonlinear accelerations on the velocity and magnetic fields to gauge the relative influence of terms that drive the system with wave-like (linear) versus turbulent (nonlinear) dynamics.

  17. N-Benzyl-2,7-diphenyl-1,4-diazepan-5-one analogues: Synthesis, spectral characterization, stereochemistry, crystal structure and molecular docking studies

    NASA Astrophysics Data System (ADS)

    Sethuvasan, S.; Sugumar, P.; Ponnuswamy, M. N.; Ponnuswamy, S.

    2016-10-01

    Three novel N-benzyl-2,7-diphenyl-1,4-diazepan-5-ones 10-12 have been synthesized via two routes starting from 2,7-diphenyl-1,4-diazepan-5-ones 4-6 and N-benzyl-2,6-diphenylpiperidin-4-ones 7-9. The structural characterization and conformational analysis of these synthesized compounds have been carried out using IR, mass and 1H, 13C, DEPT-135 and 2D (COSY and HSQC) NMR spectral techniques. The N-benzyldiazepan-5-one 10 is found to prefer chair conformation with equatorial orientation of alkyl and phenyl groups while N-benzyldiazepan-5-ones 11 &12 prefer to adopt twist-boat conformation with phenyl rings at C-2 & C-7 occupying equatorial and pseudo-axial orientations, respectively. The single crystal X-ray structure of compound 12 has been determined which also supports the twist-boat conformation. In silico molecular docking study has also been performed and the results show that the compounds 10-12 might exhibit inhibitory activity against HIV-1 protease. All the compounds are screened for their antibacterial activity against three bacterial strains (Staphylococcus aureus, Escherichia coli and Bacillus cereus) and only compound 11 shows moderate activity.

  18. Zinc(II) complexes with heterocyclic ether, acid and amide. Crystal structure, spectral, thermal and antibacterial activity studies

    NASA Astrophysics Data System (ADS)

    Jabłońska-Wawrzycka, Agnieszka; Rogala, Patrycja; Czerwonka, Grzegorz; Hodorowicz, Maciej; Stadnicka, Katarzyna

    2016-02-01

    The reaction of zinc salts with heterocyclic ether (1-ethoxymethyl-2-methylimidazole (1-ExMe-2-MeIm)), acid (pyridine-2,3-dicarboxylic acid (2,3-pydcH2)) and amide (3,5-dimethylpyrazole-1-carboxamide (3,5-DMePzCONH2)) yielded three new zinc complexes formulated as [Zn(1-ExMe-2-MeIm)2Cl2] 1, fac-[Zn(H2O)6][Zn(2,3-pydcH)3]22 and [Zn(3,5-DMePz)2(NCO)2] 3. Complexes of 1 and 3 are four-coordinated with a tetrahedron as coordination polyhedron. However, compound 2 forms an octahedral cation-anion complex. The complex 3 was prepared by eliminating of the carboxamide group from the ligand and then the 3,5-dimethylpyrazole (3,5-DMePz) and isocyanates formed were employed as new ligands. The IR and X-ray studies have confirmed a bidentate fashion of coordination of the 2,3-pydcH and monodentate fashion of coordination of the 1-ExMe-2-MeIm and 3,5-DMePz to the Zn(II) ions. The crystal packing of Zn(II) complexes are stabilized by intermolecular classical hydrogen bonds of O-H⋯O and N-H⋯O types. The most interesting feature of the supramolecular architecture of complexes is the existence of C-H⋯O, C-H⋯Cl and C-H⋯π interactions and π⋯π stacking, which also contributes to structural stabilisation. The correlation between crystal structure and thermal stability of zinc complexes is observed. In all compounds the fragments of ligands donor-atom containing go in the last steps. Additionally, antimicrobial activities of compounds were carried out against certain Gram-positive and Gram-negative bacteria and counts of CFU (colony forming units) were also determined. The achieved results confirmed a significant antibacterial activity of some tested zinc complexes. On the basis of the Δ log CFU values the antibacterial activity of zinc complexes follows the order: 3 > 2 > 1. Influence a number of N-donor atoms in zinc environment on antibacterial activity is also observed.

  19. Synthesis, structure, spectral, thermal and first-order molecular hyperpolarizability of 4-benzoylpyridine isonicotinyl hydrazone monohydrate single crystals.

    PubMed

    Meenatchi, V; Muthu, K; Rajasekar, M; Meenakshisundaram, S P

    2014-04-24

    Single crystals of 4-benzoylpyridine isonicotinyl hydrazone monohydrate were grown by slow evaporation solution growth technique from ethanol at room temperature. It belongs to triclinic system with space group P1¯ and the cell parameters are, a=8.9250(2) Å, b=9.1540(2) Å, c=10.87500(10) Å and V=797.88(3) Å(3). Powder XRD closely resembles with that of simulated pattern from single crystal XRD. The characteristic functional groups present in the molecule are confirmed by FT-IR and FT-Raman analyses. The crystal is transparent in the visible region having a lower optical cut-off at ∼420 nm and the band gap energies are estimated by the application of Kubelka-Munk algorithm. Thermal analysis by TG/DTA indicates the stability of the material. The scanning electron microscopy studies reveal the surface morphology of the as-grown crystal. Mass spectrometry provides information pertaining to the structure and molecular weight of the compound. Theoretical calculations were performed using Hartree-Fock method with 6-31G(d,p) as the basis set for to derive the optimized geometry, dipole moment and first-order molecular hyperpolarizality (β) values.

  20. Structural, energetic, and UV-Vis spectral analysis of UVA filter 4-tert-butyl-4'-methoxydibenzoylmethane.

    PubMed

    Pinto da Silva, Luís; Ferreira, Paulo J O; Duarte, Darío J R; Miranda, Margarida S; Esteves da Silva, Joaquim C G

    2014-02-27

    The growing awareness of the harmful effects of ultraviolet (UV) solar radiation has increased the production and consumption of sunscreen products, which contain organic and inorganic molecules named UV filters that absorb, reflect, or scatter UV radiation, thus minimizing negative human health effects. 4-tert-Butyl-4'-methoxydibenzoylmethane (BMDBM) is one of the few organic UVA filters and the most commonly used. BMDBM exists in sunscreens in the enol form which absorbs strongly in the UVA range. However, under sunlight irradiation tautomerization occurs to the keto form, resulting in the loss of UV protection. In this study we have performed quantum chemical calculations to study the excited-state molecular structure and excitation spectra of the enol and keto tautomers of BMDBM. This knowledge is of the utmost importance as the starting point for studies aiming at the understanding of its activity when applied on human skin and also its fate once released into the aquatic environment. The efficiency of excitation transitions was rationalized based on the concept of molecular orbital superposition. The loss of UV protection was attributed to the enol → keto phototautomerism and subsequent photodegradation. Although this process is not energetically favorable in the singlet bright state, photodegradation is possible because of intersystem crossing to the first two triplet states.

  1. Growth, structure, spectral properties and crystal-field analysis of monoclinic Nd:YNbO4 single crystal

    NASA Astrophysics Data System (ADS)

    Ding, Shoujun; Zhang, Qingli; Gao, Jinyun; Liu, Wenpeng; Luo, Jianqiao; Sun, Dunlu; Sun, Guihua; Wang, Xiaofei

    2016-12-01

    A Nd:YNbO4 single crystal was successfully grown by Czochralski (Cz) method, its structural and spectroscopic properties were investigated. The X-ray rocking curve of the (010) diffraction face of Nd:YNbO4 crystal was measured, the full width at half maximum (FWHM) of this diffraction peak is 0.05°, which indicates a high crystalline quality of the as-grown crystal. Its lattice parameters, atomic coordinates and so on were obtained by Rietvield refinement to X-ray diffraction data. According to the Archimedes drainage method, the crystal density of Nd:YNbO4 is calculated to be 5.4 g/cm3. The Mohr‧s hardness value along (010) face was determined to be 6.0. The transmission spectrum along (010) face at room temperature was recorded and the excitation and emission spectra at 8 K were measured. Photoluminescence peaks of Nd:YNbO4 were assigned, and the crystal-field splitting of Nd3+ in YNbO4 was obtained. The fluorescence lifetime of the 4F3/2→4I11/2 transition of Nd3+ in YNbO4 is fitted to be 152 μs These spectroscopic and energy splitting data give an important reference for the research of laser property of Nd:YNbO4 crystal.

  2. Synthesis, structure, spectral characterization, electrochemistry and evaluation of antibacterial potentiality of a novel oxime-based palladium(II) compound.

    PubMed

    Bandyopadhyay, Nirmalya; Zhu, Miaoli; Lu, Liping; Mitra, Debmalya; Das, Mousumi; Das, Piu; Samanta, Amalesh; Naskar, Jnan Prakash

    2015-01-07

    The title monomeric Pd(II) compound, [Pd(L)(Cl)], was synthesized in moderate yield out of the reaction of equimolar proportion of Na2[PdCl4] and 3-[(5-bromo-2-hydroxy-benzylidene)-hydrazono]-butan-2-one oxime (LH) in tetrahydrofuran milieu. LH is a 1:1 Schiff-base condensate of 2,3-butanedionemonoxime monohydrazone and 5-bromosalicylaldehyde. [Pd(L)(Cl)] has been characterized by C, H and N microanalyses, (1)H and (13)C NMR, FAB-MS, FT-IR, Raman spectra, UV-Vis spectra and molar electrical conductivity measurements. [Pd(L)(Cl)] is diamagnetic. Structural elucidation reveals that the palladium center in [Pd(L)(Cl)] is nested in 'N2OCl' coordination environment. The geometry around Pd in [Pd(L)(Cl)] is distorted square-planar. The redox behavior of [Pd(L)(Cl)] in DMF shows a reduction couple, Pd(II)/Pd(I) at -0.836 V versus Ag/AgCl. The in vitro antimicrobial activity of [Pd(L)(Cl)] was screened against both Gram-positive and Gram-negative human pathogenic bacteria. This bioactivity was substantiated with SEM study. [Pd(L)(Cl)] exhibits satisfactory bactericidal as well as bacteriostatic activity.

  3. Spatially and spectrally resolved filamentary structures in the (3/2)omega 0 emission from laser produced plasmas

    NASA Astrophysics Data System (ADS)

    Lin, Z.; Willi, O.; Rumsby, P. T.

    This study was conducted to explore the problem of filamentation of laser light in the underdense plasma corona surrounding ablatively imploded spherical targets, a phenomenon which may prevent the realization of laser-driven fusion schemes. Preliminary observations were made of filamentary structures in the (3/2)(omega sub 0) emission from microballoon targets irradiated in the ablative mode. Time integrated spectroscopy showed double and single peaked (3/2)(omega sub 0) emission spectra. A simple model for the growth and collapse of filaments was based on the movement of the density contours at the bottom of the filament with large velocity. Here the laser intensity was high and various decay instabilities and scattering processes took place. In particular the two plasmon decay instability occurred where the electron density was nc/4, a region of (3/2)(omega sub 0) emission. The model was consistent with the experimentally observed spectra and predicted the type of omega sub 0 and 2 omega sub 0 that should be observed in future experiments.

  4. Computational, spectral and structural studies of a new non linear optical crystal: 2-hydroxy pyridinium 3,5-dinitrobenzoate

    NASA Astrophysics Data System (ADS)

    Sathya, K.; Dhamodharan, P.; Dhandapani, M.

    2017-02-01

    An organic proton transfer compound, 2-hydroxy pyridinium 3,5-dinitrobenzoate (HPDA) was synthesized from 3,5-dinitro benzoic acid and 2 -hydroxy pyridine using methanol:acetone solvent mixture at room temperature and crystallized by solvent evaporation. UV-Vis, FT-IR, 1H, 13C and DEPT-135 NMR spectroscopic techniques, CHN analysis and TG-DTA were used for characterization. Single crystal XRD analysis was carried out to ascertain the molecular structure. Computational studies that include optimization of molecular geometry, natural bond analysis (NBO), Mulliken population analysis and HOMO-LUMO analysis were performed using Gaussian 09 software by B3LYP method at 6-31g basis set level. Hirshfeld analysis indicate O⋯H/H⋯O interactions are the prominent interactions confirming the presence of Nsbnd H⋯O, Osbnd H⋯O and Csbnd H⋯O hydrogen bonding.The second-order NLO property was assessed by Kurtz-Perry powder technique. Theoretical calculations indicate that hyperpolarizability of the crystal is 38 times greater than urea. The results show that the HPDA may be used for opto-electronic applications.

  5. Probing the spectral and temporal structures of macroscopic high-order harmonic generation of He in intense ultrashort laser pulses

    NASA Astrophysics Data System (ADS)

    Li, Peng-Cheng; Liu, I.-Lin; Laughlin, Cecil; Chu, Shih-I.

    2012-06-01

    We present an accurate study of macroscopic high-order harmonic generation (HHG) from He atoms in intense ultrashort laser pulses. An accurate one-electron model potential is constructed for the description of the He atoms low-lying and Rydberg states. The macroscopic high-order harmonic spectra from He atoms are obtained by solving Maxwell's equation using macroscopic single-atom induced dipole moment. Macroscopic single-atom induced dipole moment can be obtained by solving accurately the time-dependent Schr"odinger equation (TDSE) using the time-dependent generalized pseudospectral method (TDGPS). This method allows accurate and efficient propagation of the wave function with a modest number of spatial grid points, leading to the efficient treatment of the macroscopic propagation effects for HHG. Our results show fine structure and significant enhancement of the intensities of the lower harmonics due to the resonance transitions between bound states. We explain the temporal and spatial characteristics of HHG by means of the wavelet time-frequency analysis. These analyses help to understand the detailed HHG mechanisms from He atoms.

  6. Electrosynthesis, spectral and structural studies of a semi-conducting oligomer deriving from a methoxy-substituted chalcone

    NASA Astrophysics Data System (ADS)

    Aribi, Imen; Ghomrasni, Saber; Ayachi, Sahbi; Alimi, Kamel; Roudesli, Sadok; Said, Ayoub Haj

    2016-11-01

    The anodic oxidation of a substituted chalcone namely the (E)-1-(4-methoxyphenyl)-3-(3,4,5-trimethoxyphenyl) prop-2-enone (TMC) was investigated by different electrochemical techniques using a platinum working electrode in acetonitrile. On the cyclic voltammetry time scale, the TMC exhibited a single irreversible anodic peak around 1.4 V vs. Ag/AgCl and the coupling of the radical cations, issued from the first electron transfer, was the governing reaction near the electrode. Electrolysis at a constant potential revealed that an oligo o-phenylenevinylene was the main product of the anodic oxidation of TMC. The chemical structure of the isolated oligomer was elucidated by 1H, 13C NMR, and IR spectroscopy. Gel permeation chromatography indicated that the average chain length was about 5 units. In addition, the obtained oligomer was thermally stable up to 220 °C and exhibited a light emission in the indigo-blue region. Finally, a mechanism for the TMC electro-oligomerization was proposed on the basis of the electrochemical data and the theoretical calculation of the spin densities distribution for the TMC radical cation.

  7. Comparative proteomics reveal fundamental structural and functional differences between the two progeny phenotypes of a baculovirus.

    PubMed

    Hou, Dianhai; Zhang, Leike; Deng, Fei; Fang, Wei; Wang, Ranran; Liu, Xijia; Guo, Lin; Rayner, Simon; Chen, Xinwen; Wang, Hualin; Hu, Zhihong

    2013-01-01

    The replication of lepidopteran baculoviruses is characterized by the production of two progeny phenotypes: the occlusion-derived virus (ODV), which establishes infection in midgut cells, and the budded virus (BV), which disseminates infection to different tissues within a susceptible host. To understand the structural, and hence functional, differences between BV and ODV, we employed multiple proteomic methods to reveal the protein compositions and posttranslational modifications of the two phenotypes of Helicoverpa armigera nucleopolyhedrovirus. In addition, Western blotting and quantitative mass spectrometry were used to identify the localization of proteins in the envelope or nucleocapsid fractions. Comparative protein portfolios of BV and ODV showing the distribution of 54 proteins, encompassing the 21 proteins shared by BV and ODV, the 12 BV-specific proteins, and the 21 ODV-specific proteins, were obtained. Among the 11 ODV-specific envelope proteins, 8 either are essential for or contribute to oral infection. Twenty-three phosphorylated and 6 N-glycosylated viral proteins were also identified. While the proteins that are shared by the two phenotypes appear to be important for nucleocapsid assembly and trafficking, the structural and functional differences between the two phenotypes are evidently characterized by the envelope proteins and posttranslational modifications. This comparative proteomics study provides new insight into how BV and ODV are formed and why they function differently.

  8. Comparative study of local structure of two cyanobiphenyl liquid crystals by molecular dynamics method

    SciTech Connect

    Gerts, Egor D. Komolkin, Andrei V.; Burmistrov, Vladimir A.; Alexandriysky, Victor V.; Dvinskikh, Sergey V.

    2014-08-21

    Fully-atomistic molecular dynamics simulations were carried out on two similar cyanobiphenyl nematogens, HO-6OCB and 7OCB, in order to study effects of hydrogen bonds on local structure of liquid crystals. Comparable length of these two molecules provides more evident results on the effects of hydrogen bonding. The analysis of radial and cylindrical distribution functions clearly shows the differences in local structure of two mesogens. The simulations showed that anti-parallel alignment is preferable for the HO-6OCB. Hydrogen bonds between OH-groups are observed for 51% of HO-6OCB molecules, while hydrogen bonding between CN- and OH-groups occurs only for 16% of molecules. The lifetimes of H-bonds differ due to different mobility of molecular fragments (50 ps for N⋅⋅⋅H–O and 41 ps for O⋅⋅⋅H–O). Although the standard Optimized Potentials for Liquid Simulations - All-Atom force field cannot reproduce some experimental parameters quantitatively (order parameters are overestimated, diffusion coefficients are not reproduced well), the comparison of relative simulated results for the pair of mesogens is nevertheless consistent with the same relative experimental parameters. Thus, the comparative study of simulated and experimental results for the pair of similar liquid crystals still can be assumed plausible.

  9. Physcomitrella HMGA-type proteins display structural differences compared to their higher plant counterparts

    SciTech Connect

    Lyngaard, Carina; Stemmer, Christian; Stensballe, Allan; Graf, Manuela; Gorr, Gilbert; Decker, Eva; Grasser, Klaus D.

    2008-10-03

    High mobility group (HMG) proteins of the HMGA family are chromatin-associated proteins that act as architectural factors in nucleoprotein structures involved in gene transcription. To date, HMGA-type proteins have been studied in various higher plant species, but not in lower plants. We have identified two HMGA-type proteins, HMGA1 and HMGA2, encoded in the genome of the moss model Physcomitrella patens. Compared to higher plant HMGA proteins, the two Physcomitrella proteins display some structural differences. Thus, the moss HMGA proteins have six (rather than four) AT-hook DNA-binding motifs and their N-terminal domain lacks similarity to linker histone H1. HMGA2 is expressed in moss protonema and it localises to the cell nucleus. Typical of HMGA proteins, HMGA2 interacts preferentially with A/T-rich DNA, when compared with G/C-rich DNA. In cotransformation assays in Physcomitrella protoplasts, HMGA2 stimulated reporter gene expression. In summary, our data show that functional HMGA-type proteins occur in Physcomitrella.

  10. Allelic genome structural variations in maize detected by array comparative genome hybridization.

    PubMed

    Beló, André; Beatty, Mary K; Hondred, David; Fengler, Kevin A; Li, Bailin; Rafalski, Antoni

    2010-01-01

    DNA polymorphisms such as insertion/deletions and duplications affecting genome segments larger than 1 kb are known as copy-number variations (CNVs) or structural variations (SVs). They have been recently studied in animals and humans by using array-comparative genome hybridization (aCGH), and have been associated with several human diseases. Their presence and phenotypic effects in plants have not been investigated on a genomic scale, although individual structural variations affecting traits have been described. We used aCGH to investigate the presence of CNVs in maize by comparing the genome of 13 maize inbred lines to B73. Analysis of hybridization signal ratios of 60,472 60-mer oligonucleotide probes between inbreds in relation to their location in the reference genome (B73) allowed us to identify clusters of probes that deviated from the ratio expected for equal copy-numbers. We found CNVs distributed along the maize genome in all chromosome arms. They occur with appreciable frequency in different germplasm subgroups, suggesting ancient origin. Validation of several CNV regions showed both insertion/deletions and copy-number differences. The nature of CNVs detected suggests CNVs might have a considerable impact on plant phenotypes, including disease response and heterosis.

  11. Gender differences in structured risk assessment: comparing the accuracy of five instruments.

    PubMed

    Coid, Jeremy; Yang, Min; Ullrich, Simone; Zhang, Tianqiang; Sizmur, Steve; Roberts, Colin; Farrington, David P; Rogers, Robert D

    2009-04-01

    Structured risk assessment should guide clinical risk management, but it is uncertain which instrument has the highest predictive accuracy among men and women. In the present study, the authors compared the Psychopathy Checklist-Revised (PCL-R; R. D. Hare, 1991, 2003); the Historical, Clinical, Risk Management-20 (HCR-20; C. D. Webster, K. S. Douglas, D. Eaves, & S. D. Hart, 1997); the Risk Matrix 2000-Violence (RM2000[V]; D. Thornton et al., 2003); the Violence Risk Appraisal Guide (VRAG; V. L. Quinsey, G. T. Harris, M. E. Rice, & C. A. Cormier, 1998); the Offenders Group Reconviction Scale (OGRS; J. B. Copas & P. Marshall, 1998; R. Taylor, 1999); and the total previous convictions among prisoners, prospectively assessed prerelease. The authors compared predischarge measures with subsequent offending and instruments ranked using multivariate regression. Most instruments demonstrated significant but moderate predictive ability. The OGRS ranked highest for violence among men, and the PCL-R and HCR-20 H subscale ranked highest for violence among women. The OGRS and total previous acquisitive convictions demonstrated greatest accuracy in predicting acquisitive offending among men and women. Actuarial instruments requiring no training to administer performed as well as personality assessment and structured risk assessment and were superior among men for violence.

  12. Evaluating the efficiency of spectral resolution of univariate methods manipulating ratio spectra and comparing to multivariate methods: an application to ternary mixture in common cold preparation.

    PubMed

    Moustafa, Azza Aziz; Salem, Hesham; Hegazy, Maha; Ali, Omnia

    2015-02-25

    Simple, accurate, and selective methods have been developed and validated for simultaneous determination of a ternary mixture of Chlorpheniramine maleate (CPM), Pseudoephedrine HCl (PSE) and Ibuprofen (IBF), in tablet dosage form. Four univariate methods manipulating ratio spectra were applied, method A is the double divisor-ratio difference spectrophotometric method (DD-RD). Method B is double divisor-derivative ratio spectrophotometric method (DD-RD). Method C is derivative ratio spectrum-zero crossing method (DRZC), while method D is mean centering of ratio spectra (MCR). Two multivariate methods were also developed and validated, methods E and F are Principal Component Regression (PCR) and Partial Least Squares (PLSs). The proposed methods have the advantage of simultaneous determination of the mentioned drugs without prior separation steps. They were successfully applied to laboratory-prepared mixtures and to commercial pharmaceutical preparation without any interference from additives. The proposed methods were validated according to the ICH guidelines. The obtained results were statistically compared with the official methods where no significant difference was observed regarding both accuracy and precision.

  13. Evaluating the efficiency of spectral resolution of univariate methods manipulating ratio spectra and comparing to multivariate methods: An application to ternary mixture in common cold preparation

    NASA Astrophysics Data System (ADS)

    Moustafa, Azza Aziz; Salem, Hesham; Hegazy, Maha; Ali, Omnia

    2015-02-01

    Simple, accurate, and selective methods have been developed and validated for simultaneous determination of a ternary mixture of Chlorpheniramine maleate (CPM), Pseudoephedrine HCl (PSE) and Ibuprofen (IBF), in tablet dosage form. Four univariate methods manipulating ratio spectra were applied, method A is the double divisor-ratio difference spectrophotometric method (DD-RD). Method B is double divisor-derivative ratio spectrophotometric method (DD-RD). Method C is derivative ratio spectrum-zero crossing method (DRZC), while method D is mean centering of ratio spectra (MCR). Two multivariate methods were also developed and validated, methods E and F are Principal Component Regression (PCR) and Partial Least Squares (PLSs). The proposed methods have the advantage of simultaneous determination of the mentioned drugs without prior separation steps. They were successfully applied to laboratory-prepared mixtures and to commercial pharmaceutical preparation without any interference from additives. The proposed methods were validated according to the ICH guidelines. The obtained results were statistically compared with the official methods where no significant difference was observed regarding both accuracy and precision.

  14. Synthesis, structural and spectroscopic studies of two new benzimidazole derivatives: A comparative study

    NASA Astrophysics Data System (ADS)

    Saral, Hasan; Özdamar, Özgür; Uçar, İbrahim

    2017-02-01

    In the present work, structural and spectroscopic studies on 1-Methyl-2-(2‧-hydroxy-4‧-chlorophenyl)benzimidazole (1) and 1-Methyl-2-(2‧-hydroxy-4‧-methoxyphenyl)benzimidazole (2), have been carried out extensively by X-ray diffraction, HRMS, UV-Vis, FT-IR and 1H and 13C NMR spectroscopy. The crystal structure of both compounds is stabilized by Osbnd H⋯N hydrogen bond and π-π interactions. Contrary to compound 1, the skeleton of compound 2 is considerably deviated from the planarity probably caused by intermolecular hydrogen bonding. The experimental results were compared to the theoretical ones, obtained at DFT level. Ground state geometry, electronic structure, vibrational and NMR spectra have been performed using the B3LYP functional with the 6-31 G(d,p) basis set. It was observed that the bond distances and angles in the both compounds were in good with those of the experiment. The energetic behaviors of the both compounds in methanol solvent were examined using by time-dependent DFT (TD-DFT) method by applying the polarizable continuum model (PCM). Isotropic chemical shifts (13C and 1H NMR) were calculated using the gauge-invariant atomic orbital (GIAO) method. The HOMO and LUMO analyses were used to elucidate information regarding charge transfer within the molecule.

  15. Comparative Evaluation for Brain Structural Connectivity Approaches: Towards Integrative Neuroinformatics Tool for Epilepsy Clinical Research

    PubMed Central

    Yang, Sheng; Tatsuoka, Curtis; Ghosh, Kaushik; Lacuey-Lecumberri, Nuria; Lhatoo, Samden D.; Sahoo, Satya S.

    2016-01-01

    Recent advances in brain fiber tractography algorithms and diffusion Magnetic Resonance Imaging (MRI) data collection techniques are providing new approaches to study brain white matter connectivity, which play an important role in complex neurological disorders such as epilepsy. Epilepsy affects approximately 50 million persons worldwide and it is often described as a disorder of the cortical network organization. There is growing recognition of the need to better understand the role of brain structural networks in the onset and propagation of seizures in epilepsy using high resolution non-invasive imaging technologies. In this paper, we perform a comparative evaluation of two techniques to compute structural connectivity, namely probabilistic fiber tractography and statistics derived from fractional anisotropy (FA), using diffusion MRI data from a patient with rare case of medically intractable insular epilepsy. The results of our evaluation demonstrate that probabilistic fiber tractography provides a more accurate map of structural connectivity and may help address inherent complexities of neural fiber layout in the brain, such as fiber crossings. This work provides an initial result towards building an integrative informatics tool for neuroscience that can be used to accurately characterize the role of fiber tract connectivity in neurological disorders such as epilepsy. PMID:27570685

  16. Comparing nonlinear texture measures for quantifying trabecular bone structures using surrogates

    NASA Astrophysics Data System (ADS)

    Rath, Christoph W.; Monetti, Roberto A.; Muller, Dirk; Bohm, Holger; Rummeny, Ernst J.; Link, Thomas M.

    2004-05-01

    We generalize the methods of constrained randomization in order to assess different nonlinear texture measures for the quantitative characterisation of trabecular bone structures as seen in high resolution MR images of the distal radius for patients with and without osteoporotic bone fractures. We demonstrate that it is feasible to produce surrogates which preserve texture measures sensitive to higher-order correlations. Specifically, we preserve for two-dimensional images the three Minkowski functionals (MF) which can be interpreted as the surface, the perimeter and the Euler-Characteristic of an excursion set. The surrogates preserving the MF's are generated by using simulated annealing techniques, where the constraints are specified in terms of a cost function which has a global minimum when the constraints are fulfilled. The cost function has to be minimized among all permutations of the image pixels. The surrogates and the original data are quantified by estimating their local scaling properties by means of the calculation of the spectrum of weighted scaling indices (WSI). It is shown that a significant discrimination between original and surrogate data is made possible by comparing the probability distributions of the weighted scaling indices. This proves that the two nonlinear texture measures (MF an WSI) are complementary since they are sensitive to different morphological aspects of the trabecular bone structures. It turns out that the generalized method of constrained randomization is a vital tool for assessing the quality of texture measures in terms of sensitivity to images structures and discrimination power.

  17. Comparative study of particle structure evolution during water sorption: skim and whole milk powders.

    PubMed

    Murrieta-Pazos, I; Gaiani, C; Galet, L; Cuq, B; Desobry, S; Scher, J

    2011-10-01

    Surface composition of dairy powders influences significantly a quantity of functional properties such as rehydration, caking, agglomeration. Nevertheless, the kinetic of water uptake by the powders was never directly related to the structure and the composition of the surface. In this work, the effect of relative humidity on the structural reorganization of two types of dairy powder was studied. The water-powder interaction for industrial whole milk powder, and skim milk powder was studied using dynamic vapor sorption. The water sorption isotherms were fitted with a Brunner-Emmet-Teller model and each stage of the sorption curve was analyzed with a Fickian diffusion. The water content in the monolayer predicted for each powder and the moisture diffusivity calculated were discussed and compared. Concurrently, powders microstructure and powders surface under variable relative humidity were assessed by X-ray photoelectron spectroscopy, scanning electron microscopy coupled with energy dispersive X-ray and atomic force microscopy. A correlation between the data obtained from the sorption isotherms and the modifications of structure allowed us to conclude that powder microstructure and chemical state of the components could play an important role in determining the water diffusivity.

  18. Comparative Structural and Functional Analysis of Bunyavirus and Arenavirus Cap-Snatching Endonucleases

    PubMed Central

    Reguera, Juan; Gerlach, Piotr; Rosenthal, Maria; Gaudon, Stephanie; Coscia, Francesca; Günther, Stephan; Cusack, Stephen

    2016-01-01

    Segmented negative strand RNA viruses of the arena-, bunya- and orthomyxovirus families uniquely carry out viral mRNA transcription by the cap-snatching mechanism. This involves cleavage of host mRNAs close to their capped 5′ end by an endonuclease (EN) domain located in the N-terminal region of the viral polymerase. We present the structure of the cap-snatching EN of Hantaan virus, a bunyavirus belonging to hantavirus genus. Hantaan EN has an active site configuration, including a metal co-ordinating histidine, and nuclease activity similar to the previously reported La Crosse virus and Influenza virus ENs (orthobunyavirus and orthomyxovirus respectively), but is more active in cleaving a double stranded RNA substrate. In contrast, Lassa arenavirus EN has only acidic metal co-ordinating residues. We present three high resolution structures of Lassa virus EN with different bound ion configurations and show in comparative biophysical and biochemical experiments with Hantaan, La Crosse and influenza ENs that the isolated Lassa EN is essentially inactive. The results are discussed in the light of EN activation mechanisms revealed by recent structures of full-length influenza virus polymerase. PMID:27304209

  19. Thermodynamic and structural insights into nanocomposites engineering by comparing two materials assembly techniques for graphene.

    PubMed

    Zhu, Jian; Zhang, Huanan; Kotov, Nicholas A

    2013-06-25

    Materials assembled by layer-by-layer (LBL) assembly and vacuum-assisted flocculation (VAF) have similarities, but a systematic study of their comparative advantages and disadvantages is missing. Such a study is needed from both practical and fundamental perspectives aiming at a better understanding of structure-property relationships of nanocomposites and purposeful engineering of materials with unique properties. Layered composites from polyvinyl alcohol (PVA) and reduced graphene (RG) are made by both techniques. We comparatively evaluate their structure, mechanical, and electrical properties. LBL and VAF composites demonstrate clear differences at atomic and nanoscale structural levels but reveal similarities in micrometer and submicrometer organization. Epitaxial crystallization and suppression of phase transition temperatures are more pronounced for PVA in LBL than for VAF composites. Mechanical properties are virtually identical for both assemblies at high RG contents. We conclude that mechanical properties in layered RG assemblies are largely determined by the thermodynamic state of PVA at the polymer/nanosheet interface rather than the nanometer scale differences in RG packing. High and nearly identical values of toughness for LBL and VAF composites reaching 6.1 MJ/m(3) observed for thermodynamically optimal composition confirm this conclusion. Their toughness is the highest among all other layered assemblies from RG, cellulose, clay, etc. Electrical conductivity, however, is more than 10× higher for LBL than for VAF composites for the same RG contents. Electrical properties are largely determined by the tunneling barrier between RG sheets and therefore strongly dependent on atomic/nanoscale organization. These findings open the door for application-oriented methods of materials engineering using both types of layered assemblies.

  20. Large-Scale Structure of the Molecular Gas in Taurus Revealed by High Linear Dynamic Range Spectral Line Mapping

    NASA Astrophysics Data System (ADS)

    Goldsmith, Paul F.; Heyer, Mark; Narayanan, Gopal; Snell, Ronald; Li, Di; Brunt, Chris

    2008-06-01

    We report the results of a 100 deg2 survey of the Taurus molecular cloud region in 12CO and 13CO J = 1→ 0. The image of the cloud in each velocity channel includes simeq3 × 106 Nyquist-sampled pixels on a 20'' grid. The high sensitivity and large spatial dynamic range of the maps reveal a very complex, highly structured cloud morphology, including filaments, cavities, and rings. The axes of the striations seen in the 12CO emission from relatively diffuse gas are aligned with the direction of the magnetic field. We have developed a statistical method for analyzing the pixels in which 12CO but not 13CO is detected, which allows us to determine the CO column in the diffuse portion of the cloud, as well as in the denser regions in which we detect both isotopologues. Using a column-density-dependent model for the CO fractional abundance, we derive the mass of the region mapped to be 2.4 × 104 M⊙, more than twice as large as would be obtained using a canonical fixed fractional abundance of 13CO, and a factor of 3 greater than would be obtained considering only the high column density regions. We determine that half the mass of the cloud is in regions having column density below 2.1 × 1021 cm-2. The distribution of young stars in the region covered is highly nonuniform, with the probability of finding a star in a pixel with a specified column density rising sharply for N(H2) = 6 × 1021 cm-2. We determine a relatively low star formation efficiency (mass of young stars/mass of molecular gas), between 0.3% and 1.2%, and an average star formation rate during the past 3 Myr of 8 × 10-5 stars yr-1.

  1. Spectral and structural characterization of amidate-bridged platinum-thallium complexes with strong metal-metal bonds.

    PubMed

    Chen, Wanzhi; Liu, Fenghui; Matsumoto, Kazuko; Autschbach, Jochen; Le Guennic, Boris; Ziegler, Tom; Maliarik, Mikhail; Glaser, Julius

    2006-05-29

    The reactions of [Pt(NH3)2(NHCOtBu)2] and TlX3 (X = NO3-, Cl-, CF3CO2-) yielded dinuclear [{Pt(ONO2)(NH3)2(NHCOtBu)}Tl(ONO2)2(MeOH)] (2) and trinuclear complexes [{PtX(RNH2)2(NHCOtBu)2}2Tl]+ [X = NO3- (3), Cl- (5), CF3CO2- (6)], which were spectroscopically and structurally characterized. Strong Pt-Tl interaction in the complexes in solutions was indicated by both 195Pt and 205Tl NMR spectra, which exhibit very large one-bond spin-spin coupling constants between the heteronuclei (1J(PtTl)), 146.8 and 88.84 kHz for 2 and 3, respectively. Both the X-ray photoelectron spectra and the 195Pt chemical shifts reveal that the complexes have Pt centers whose oxidation states are close to that of Pt(III). Characterization of these complexes by X-ray diffraction analysis confirms that the Pt and Tl atoms are held together by very short Pt-Tl bonds and are supported by the bridging amidate ligands. The Pt-Tl bonds are shorter than 2.6 Angstrom, indicating a strong metal-metal attraction between these two metals. Compound 2 was found to activate the C-H bond of acetone to yield a platinum(IV) acetonate complex. This reactivity corresponds to the property of Pt(III) complexes. Density functional theory calculations were able to reproduce the large magnitude of the metal-metal spin-spin coupling constants. The couplings are sensitive to the computational model because of a delicate balance of metal 6s contributions in the frontier orbitals. The comp