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Sample records for bidimensional abrangente gcxgc

  1. Partially oxidised organic components in urban aerosol using GCXGC-TOF/MS

    NASA Astrophysics Data System (ADS)

    Hamilton, J. F.; Webb, P. J.; Lewis, A. C.; Hopkins, J. R.; Smith, S.; Davy, P.

    2004-08-01

    Partially oxidised organic compounds associated with PM2.5 aerosol collected in London, England, have been analysed using direct thermal desorption coupled to comprehensive gas chromatography-time of flight mass spectrometry (GCXGC-TOF/MS). Over 10000 individual organic components were isolated from around 10µg of aerosol material in a single procedure and with no sample pre-treatment. Chemical functionalities observed using this analytical technique ranged from alkanes to poly-oxygenated species. The chemical band structures commonly used in GCXGC for group type identifications overlap for this sample type, and have required mass spectrometry as an additional level of instrument dimensionality. An investigation of oxygenated volatile organic compounds (o-VOC) contained within urban aerosol has been performed and in a typical sample around 130 o-VOCs were identified based on retention behaviour and spectral match. In excess of 100 other oxygenated species were also observed but lack of mass spectral library or pure components prevents positive identification. Many of the carbonyl species observed could be mechanistically linked to gas phase aromatic hydrocarbon oxidation and there is good agreement in terms of speciation between the urban samples analysed here and those degradation products observed in smog chamber experiments of aromatic oxidation. The presence of partially oxidised species such as linear chain aldehydes and ketones and cyclic products such as furanones suggests that species generated early in the oxidative process may undergo gas to particle partitioning despite their relatively high volatility.

  2. Kawasaki Dynamics on Bidimensional Spin Systems

    NASA Astrophysics Data System (ADS)

    Resende, Denilson C.; Cacüador, Felipe C.; Dantas, Sócrates O.

    Under the influence of an external field many systems exhibit slow relaxations processes. In that sense, we study the Physics of this behavior/process in the early stages of its evolution on bidimensional Ising systems using Monte Carlo simulations at a broad range of temperature and spins up concentration. The Monte Carlo simulations were done up to second neighbors interactions shown a more stable dynamic regime than first neighbors interactions, when the systems energy is considered. The behavior of relative energy/spin and the relative perimeter (the line between spin up and spin down regions) are monitored against Monte Carlo steps. Also, our findings show that the stretching index (a2) exhibit values below the borderline (1) in a broad range of concentration below 50% and temperature from 0.5 ≤T ≤ 4.5 (in units of J/kB , where J is the ferromagnetic constant and kB is the Boltzmann constant).

  3. Using Comprehensive Two-dimensional Gas Chromatography (GCxGC) for the Analysis of Volatile Organic Compounds (VOCs)

    NASA Astrophysics Data System (ADS)

    Lidster, R. T.; Hamilton, J. F.; Lewis, A. C.; Lee, J. D.; Hopkins, J. R.; Punjabi, S.

    2012-04-01

    Volatile organic compounds (VOC) play an important role in atmospheric chemistry through their contribution to the formation of ozone and secondary organic aerosol, both of which may lead to human health impacts. VOC monitoring and quantification has traditionally used techniques like gas chromatography and mass spectrometry, with methods developed to target specific groups of compounds. However studies have shown that in some locations the VOC loading in the atmosphere is not fully accounted for. Comprehensive two-dimensional Gas chromatography (GC-GC) utilises two columns coupled via a modulator and can give rise to significant increases in resolution and peak capacity. Used in combination with mass spectrometry it makes a powerful tool for complex sample analysis. Unfortunately GC-GC has found only limited application in atmospheric chemistry due to the instrument size, expense, power consumption and cryogen requirement. GC-GC-TOF/MS has been used to analyse Whole Air Samples (WAS) collected onboard the FAAM research aircraft as part of the "ROle of Nighttime chemistry in controlling the Oxidising Capacity of the AtmOsphere" (RONOCO) campaign. RONOCO studied the transformation of pollutants during nightime over the UK and North Sea. GCxGC results have shown good agreement with an established GC-FID instrument and the comprehensive analysis has allowed for the identification and quantification of additional species not covered by the GC-FID system. The higher molecular weight aromatic compounds detected showed a strong correlation with toluene and this has enabled the calculation of proportionally factors. The additional reactive carbon identified using GC-GC is calculated to provide a large OH sink and may account for some of the missing reactivity seen in previous studies. A number of additional NO3 sink compounds were also identified, although their impact is likely to be small due to their reactivity. Further work has also been carried out on the development

  4. Micropolar continuum modelling of bi-dimensional tetrachiral lattices

    PubMed Central

    Chen, Y.; Liu, X. N.; Hu, G. K.; Sun, Q. P.; Zheng, Q. S.

    2014-01-01

    The in-plane behaviour of tetrachiral lattices should be characterized by bi-dimensional orthotropic material owing to the existence of two orthogonal axes of rotational symmetry. Moreover, the constitutive model must also represent the chirality inherent in the lattices. To this end, a bi-dimensional orthotropic chiral micropolar model is developed based on the theory of irreducible orthogonal tensor decomposition. The obtained constitutive tensors display a hierarchy structure depending on the symmetry of the underlying microstructure. Eight additional material constants, in addition to five for the hemitropic case, are introduced to characterize the anisotropy under Z2 invariance. The developed continuum model is then applied to a tetrachiral lattice, and the material constants of the continuum model are analytically derived by a homogenization process. By comparing with numerical simulations for the discrete lattice, it is found that the proposed continuum model can correctly characterize the static and wave properties of the tetrachiral lattice. PMID:24808754

  5. Percolation and coarsening in the bidimensional voter model

    NASA Astrophysics Data System (ADS)

    Tartaglia, Alessandro; Cugliandolo, Leticia F.; Picco, Marco

    2015-10-01

    We study the bidimensional voter model on a square lattice with numerical simulations. We demonstrate that the evolution takes place in two distinct dynamic regimes; a first approach towards critical site percolation and a further approach towards full consensus. We calculate the time dependence of the two growing lengths, finding that they are both algebraic but with different exponents (apart from possible logarithmic corrections). We analyze the morphology and statistics of clusters of voters with the same opinion. We compare these results to the ones for curvature driven two-dimensional coarsening.

  6. Heat string model of bi-dimensional dc Glidarc

    NASA Astrophysics Data System (ADS)

    Pellerin, S.; Richard, F.; Chapelle, J.; Cormier, J.-M.; Musiol, K.

    2000-10-01

    The gliding arc discharge (`Glidarc') is the subject of renewed interest in application to a variety of chemical reactions. The gliding arc creates a weakly ionized gas `string' between two horn-shaped electrodes. In this paper, we present a simple model for a bi-dimensional dc Glidarc working in air, in which the conducting zone of the discharge that is heated by the Joule effect is considered as a hot wire cooled by an air flow. Inside this wire, the heat transfer results from thermal conduction. The exchange of heat between the hot wire and the air flow is assured by convection and depends on the wire radius and the relative velocity of the arc with respect to the gas flow. The model correctly describes experimental results and allows us to predict the working parameters of the Glidarc in different experimental situations.

  7. Single Photon Avalanche Diodes: Towards the Large Bidimensional Arrays

    PubMed Central

    Privitera, Simona; Tudisco, Salvatore; Lanzanò, Luca; Musumeci, Francesco; Pluchino, Alessandro; Scordino, Agata; Campisi, Angelo; Cosentino, Luigi; Finocchiaro, Paolo; Condorelli, Giovanni; Mazzillo, Massimo; Lombardo, Salvo; Sciacca, Emilio

    2008-01-01

    Single photon detection is one of the most challenging goals of photonics. In recent years, the study of ultra-fast and/or low-intensity phenomena has received renewed attention from the academic and industrial communities. Intense research activity has been focused on bio-imaging applications, bio-luminescence, bio-scattering methods, and, more in general, on several applications requiring high speed operation and high timing resolution. In this paper we present design and characterization of bi-dimensional arrays of a next generation of single photon avalanche diodes (SPADs). Single photon sensitivity, dark noise, afterpulsing and timing resolution of the single SPAD have been examined in several experimental conditions. Moreover, the effects arising from their integration and the readout mode have also been deeply investigated.

  8. Affective biases in English are bi-dimensional.

    PubMed

    Warriner, Amy Beth; Kuperman, Victor

    2015-01-01

    A long-standing observation about the interface between emotion and language is that positive words are used more frequently than negative ones, leading to the Pollyanna hypothesis which alleges a predominantly optimistic outlook in humans. This paper uses the largest available collection of affective ratings as well as insights from linguistics to revisit the Pollyanna hypothesis as it relates to two dimensions of emotion: valence (pleasantness) and arousal (intensity). We identified systematic patterns in the distribution of words over a bi-dimensional affective space, which (1) run counter to and supersede most prior accounts, and (2) differ drastically between word types (unique, distinct words in the lexicon) and word tokens (number of occurrences of available words in the lexicon). We argue for two factors that shape affect in language and society: a pro-social benevolent communication strategy with its emphasis on useful and dangerous phenomena, and the structure of human subjective perception of affect. PMID:25313685

  9. Bidimensional spectroscopy of double galaxies. I. Markarian 463.

    NASA Astrophysics Data System (ADS)

    Chatzichristou, E. T.; Vanderriest, C.

    1995-06-01

    We report on photometry and bidimensional spectroscopy of the double-nucleus galaxy Mkn 463 (E and W). The high spatial resolution and large wavelength coverage of the integral field spectrograph SILFID under sub-arcsec resolution conditions allow us to map the kinematics and ionization structure of the extended emitting gas and subsequently to identify the individual components of this complex system. Detailed spectroscopy of the nuclear regions confirms the Seyfert 2 characteristics of the E (east) component (known to be a "hidden" Seyfert 1) while placing the W (west) component on the Veilleux-Osterbrock diagrams in the region between Seyfert 2s and LINERs. The highest ionization occurs in and around the east nucleus. 3-4" to the north the line widths seem to correlate with the strength of the low ionization lines, this being suggestive of an additional ionizing mechanism operating in these regions. The N-S collimated emission originating from the E nucleus is a striking feature on the [OIII]_5007_ and Hα reconstructed images and on the V-R colour map. The relatively high ionization of the emitting gas ~14" south of the E nucleus may be due either to beamed ionizing radiation from the nucleus or to ionization by "in situ" generated continuum. The velocity maps constructed for the [OIII]_5007_, Hα and Hβ lines at the peak 80% and 50% intensity levels reveal a SE-NW velocity gradient of ~450km/s with a sharply blue-shifted region within 2" NE of the E nucleus. This velocity gradient, previously undetected, is discussed in relation with the presence of a radio component in the same region. The optical jet of the E nucleus and a very blue region westwards of the W nucleus, discovered on HST images, are detected on our direct images and the B-V colour map. We discuss some further correlations between the kinematical and physical conditions and discuss the implications of these new results for the understanding of this complex system.

  10. Effect of pressure and hydrogen flow in nucleation density and morphology of graphene bidimensional crystals

    NASA Astrophysics Data System (ADS)

    Chaitoglou, S.; Bertran, E.

    2016-07-01

    In this paper we present new results concerning the growth of graphene by low pressure chemical vapor deposition on polycrystalline copper foils and using methane as carbon precursor. We have studied the role of hydrogen and pressure in graphene growth on substrates of polycrystalline copper foil and we have examined how they affect the nucleation density and the size of graphene bidimensional crystals. For that, small ranges of pressure (between 10 and 30 Pa) and hydrogen flow (between 10 and 20 sccm) were explored. In addition, the antagonism between two of the main effects of hydrogen was studied. Hydrogen promotes the growth but, at the same time, applies an intense dry etching during the growth process of graphene. The challenge of the present study is to find the equilibrium between these two effects so that, the growth of highly ordered crystals on copper becomes possible. The results reveal that the total pressure during the growth process of graphene affects the size as well as the nucleation density of the graphene bidimensional crystals on polycrystalline copper. Besides, the hydrogen flow affects the morphology and quality of the graphene layer. An important parameter for a correct interpretation of the results is the change of the partial pressure ratio, < {P}{{{H}}2}> /< {P}{{{C}{{H}}}4}> , during the growth process under a constant flow of H2 and CH4. Dendritic graphene crystals with lobe lengths around 30 μm along with a nucleation density of 25 nuclei/10 000 μm2 were obtained in the studied technological conditions, which corroborates that a low nucleation of graphene is required to obtain large graphene islands and a low number of crystal boundaries. Raman spectroscopy and scanning electron microscopy evidenced the effects of hydrogen on the characteristics of growth and morphology of the graphene dendritic bidimensional crystals.

  11. On the illumination compensation of retinal images by means of the bidimensional empirical mode decomposition

    NASA Astrophysics Data System (ADS)

    Marrugo, Andrés. G.; Vargas, Raúl; Chirino, Melet; Millán, María. S.

    2015-12-01

    Retinal images are used for diagnostic purposes by ophthalmologists. However, despite controlled conditions in acquisition retinal images often suffer from non-uniform illumination which hinder their clinical use. In this work we propose the compensation of the illumination by modeling the intensity as a sum of non-stationary signals using bidimensional empirical mode decomposition (BEMD). We compare the estimation and compensation of the background illumination with a widely used technique based retinal image pixel classification. The proposed method has shown to provide a better estimation of the background illumination, particularly in complicated areas such as the optic disk (usually bright) and the periphery of fundus images (usually dim).

  12. Bidimensional assemblies of nonspherical gold nanoparticles for SERS analysis of biomolecules

    NASA Astrophysics Data System (ADS)

    Matteini, Paolo; de Angelis, Marella; Ulivi, Lorenzo; Centi, Sonia; Pini, Roberto

    2015-03-01

    Direct SERS analysis of proteins has been mainly devoted to the characterization of short peptide fragments or to the prosthetic group of metallo-proteins due to their strong SERS response. Nonetheless, this perspective restricts the investigation to very limited peptide sequences and appears of scarce interest for a thorough characterization of the protein. We tried to overcome the above limitations by setting-up an effective platform for the structural SERS detection of proteins. Our proposal escapes the needs of a preliminary modification of the biomolecule and confers rapidity and reproducibility to the analysis. Optimal results are achieved by the use of nonspherical tipped metallic nanostructures with controlled architectural parameters and their assembly into organized bidimensional arrays including a regular distribution of hot spots for protein entrapment and detection. The investigation evidenced that both the contact points between nanoparticle corners and the holes at the interface between nanoparticles are responsible for substantial SERS activity.

  13. The Bidimensional Impression Management Index (BIMI): measuring agentic and communal forms of impression management.

    PubMed

    Blasberg, Sabrina A; Rogers, Katherine H; Paulhus, Delroy L

    2014-01-01

    Measures of impression management have yet to incorporate two-factor models of person perception. The 2 primary factors are often labeled agency and communion. In Study 1, we assembled a new measure of impression management—the Bidimensional Impression Management Index (BIMI): It comprises 2 subscales designed specifically to tap agentic and communal content. Both subscales showed adequate alpha reliabilities under both honest and faking conditions. In Study 2, the BIMI was cross-validated in a new sample: The subscales remained relatively independent, and their reliabilities remained solid. A coherent pattern of personality correlates also supported the validities of both subscales. In Study 3, the differential sensitivity of the 2 subscales was demonstrated by manipulating the job type in simulated job applications. Implications and applications of the BIMI are discussed. PMID:24328818

  14. Bidimensional Lens Systems : A Rational Approach To Group Displacements During Focusing And/Or Zooming

    NASA Astrophysics Data System (ADS)

    Angénieux, J. P. L.

    1987-06-01

    Modern objective lenses for cinematography, television or photography, and particularly zoom lenses, are composed of several groups of lenses which are axially displaced during zooming and/or focusing. The number of these groups has increased recently as well as the complexity of their relative movements and functions. In this paper, we give a short history of zooming and focusing techniques ; we discuss the inconvenience of traditional solutions. We then introduce the concept of bidimensional law. We propose a systematic classification of possible lens-types according to the 4 possible types of group. We finally present a few types of lenses in the form of truth tables and parametered diagrams explaining which groups move and how during focusing and/or zooming.

  15. Bidimensional simulation of oil and gas generation and entrapment across Northern Viking graben (Norway), with emphasis on hydraulic regime

    SciTech Connect

    Burrus, J.; Ungerer, P.; Doligez, B.; Rabiller, P.

    1988-01-01

    A bidimensional forward numerical model was used to reconstruct the history of sedimentation, compaction, heat transfer, hydrocarbon generation, and migration along a 150-km southeast-northwest cross section in the Northern Viking graben. The model is based on the heat equation and on the diphasic Darcy's law. An empirical relationship between porosity and effective stress was used to study the pressure regime. The model takes into account hydraulic fracturing and subsequent relaxation of pressures. A kinetic model describes the generation of hydrocarbon.

  16. Controlling the dynamics of a bidimensional gel above and below its percolation transition

    NASA Astrophysics Data System (ADS)

    Orsi, D.; Ruta, B.; Chushkin, Y.; Pucci, A.; Ruggeri, G.; Baldi, G.; Rimoldi, T.; Cristofolini, L.

    2014-04-01

    The morphology and the microscopic internal dynamics of a bidimensional gel formed by spontaneous aggregation of gold nanoparticles confined at the water surface are investigated by a suite of techniques, including grazing-incidence x-ray photon correlation spectroscopy (GI-XPCS). The range of concentrations studied spans across the percolation transition for the formation of the gel. The dynamical features observed by GI-XPCS are interpreted in view of the results of microscopic imaging; an intrinsic link between the mechanical modulus and internal dynamics is demonstrated for all the concentrations. Our work presents an example of a transition from a stretched to a compressed correlation function actively controlled by quasistatically varying the relevant thermodynamic variable. Moreover, by applying a model proposed some time ago by Duri and Cipelletti [Europhys. Lett. 76, 972 (2006), 10.1209/epl/i2006-10357-4] we are able to build a master curve for the shape parameter, whose scaling factor allows us to quantify a "long-time displacement length." This characteristic length is shown to converge, as the concentration is increased, to the "short-time localization length" determined by pseudo-Debye-Waller analysis of the initial contrast. Finally, the intrinsic dynamics of the system is then compared with that induced by means of a delicate mechanical perturbation applied to the interface.

  17. Image denoising in bidimensional empirical mode decomposition domain: the role of Student's probability distribution function.

    PubMed

    Lahmiri, Salim

    2016-03-01

    Hybridisation of the bi-dimensional empirical mode decomposition (BEMD) with denoising techniques has been proposed in the literature as an effective approach for image denoising. In this Letter, the Student's probability density function is introduced in the computation of the mean envelope of the data during the BEMD sifting process to make it robust to values that are far from the mean. The resulting BEMD is denoted tBEMD. In order to show the effectiveness of the tBEMD, several image denoising techniques in tBEMD domain are employed; namely, fourth order partial differential equation (PDE), linear complex diffusion process (LCDP), non-linear complex diffusion process (NLCDP), and the discrete wavelet transform (DWT). Two biomedical images and a standard digital image were considered for experiments. The original images were corrupted with additive Gaussian noise with three different levels. Based on peak-signal-to-noise ratio, the experimental results show that PDE, LCDP, NLCDP, and DWT all perform better in the tBEMD than in the classical BEMD domain. It is also found that tBEMD is faster than classical BEMD when the noise level is low. When it is high, the computational cost in terms of processing time is similar. The effectiveness of the presented approach makes it promising for clinical applications. PMID:27222723

  18. Testing the bi-dimensional effects of attitudes on behavioural intentions and subsequent behaviour.

    PubMed

    Elliott, Mark A; Brewster, Sarah E; Thomson, James A; Malcolm, Carly; Rasmussen, Susan

    2015-11-01

    Attitudes are typically treated as unidimensional predictors of both behavioural intentions and subsequent behaviour. On the basis of previous research showing that attitudes comprise two independent, positive and negative dimensions, we hypothesized that attitudes would be bi-dimensional predictors of both behavioural intentions and subsequent behaviour. We focused on health-risk behaviours. We therefore also hypothesized that the positive dimension of attitude (evaluations of positive behavioural outcomes) would better predict both behavioural intentions and subsequent behaviour than would the negative dimension, consistent with the positivity bias/offset principle. In Study 1 (cross sectional design), N = 109 university students completed questionnaire measures of their intentions to binge-drink and the positive and negative dimensions of attitude. Consistent with the hypotheses, both attitude dimensions independently predicted behavioural intentions and the positive dimension was a significantly better predictor than was the negative dimension. The same pattern of findings emerged in Study 2 (cross sectional design; N = 186 university students) when we predicted intentions to binge-drink, smoke and consume a high-fat diet. Similarly, in Study 3 (prospective design; N = 1,232 speed limit offenders), both the positive and negative dimensions of attitude predicted subsequent (6-month post-baseline) speeding behaviour on two different road types and the positive dimension was the better predictor. The implications for understanding the motivation of behaviour and the development of behaviour-change interventions are discussed. PMID:25440892

  19. Bidimensional intercalation of Ge between SiC(0001) and a heteroepitaxial graphite top layer

    SciTech Connect

    Kubler, L.; Dentel, D.; Bischoff, J.-L.; Derivaz, M.; Aiet-Mansour, K.; Diani, M.

    2005-09-15

    High temperature annealing of 4H- or 6H-SiC(0001) crystals is well known to desorb Si from the surface and to generate a C-rich (6{radical}3x6{radical}3)R30 deg. (6{radical}3) reconstruction explained as a graphite monolayer in heteroepitaxial registry with the substrate. Ge deposition at room temperature and in the monolayer range on this graphitized reconstruction results in Ge islands. Using a number of surface techniques, we follow subsequent Ge morphology evolutions as a function of isochronal post-annealing treatments at increasing temperatures. In a particular temperature window Ge reacts with the substrate by diffusion under the graphite planes and wets the Si-terminated SiC surface. In spite of this bidimensional insertion of a Ge layer, the epitaxial relationship between the SiC substrate and the graphite is maintained as shown by very clear graphite-(1x1) LEED or RHEED patterns. They denote extended and well-ordered graphite planes at the surface of a graphite/Ge/SiC heterostructure. XPS analyses reveal a complete passivation of the intercalated Ge layer against oxidation by the overlying graphite sheets. Moreover, drastic spectroscopic changes on the bulk-SiC Si 2p and C 1s core levels are observed, depending on whether graphite(6{radical}3)/SiC or graphite(1x1)/Ge/SiC terminations are analyzed. In the latter case, the observed core level splitting of the bulk components is interpreted by a significant upward band bending ({approx}1.2 eV) of the n-doped SiC, making this second interface to act as a Schottky barrier. Above 1300 deg. C, a delayed Ge desorption takes place that allows the graphite sheets to re-form in their initial 6{radical}3 form, i.e., without Ge and with flatter bands.

  20. Automated screening system for retinal health using bi-dimensional empirical mode decomposition and integrated index.

    PubMed

    Acharya, U Rajendra; Mookiah, Muthu Rama Krishnan; Koh, Joel E W; Tan, Jen Hong; Bhandary, Sulatha V; Rao, A Krishna; Fujita, Hamido; Hagiwara, Yuki; Chua, Chua Kuang; Laude, Augustinus

    2016-08-01

    Posterior Segment Eye Diseases (PSED) namely Diabetic Retinopathy (DR), glaucoma and Age-related Macular Degeneration (AMD) are the prime causes of vision loss globally. Vision loss can be prevented, if these diseases are detected at an early stage. Structural abnormalities such as changes in cup-to-disc ratio, Hard Exudates (HE), drusen, Microaneurysms (MA), Cotton Wool Spots (CWS), Haemorrhages (HA), Geographic Atrophy (GA) and Choroidal Neovascularization (CNV) in PSED can be identified by manual examination of fundus images by clinicians. However, manual screening is labour-intensive, tiresome and time consuming. Hence, there is a need to automate the eye screening. In this work Bi-dimensional Empirical Mode Decomposition (BEMD) technique is used to decompose fundus images into 2D Intrinsic Mode Functions (IMFs) to capture variations in the pixels due to morphological changes. Further, various entropy namely Renyi, Fuzzy, Shannon, Vajda, Kapur and Yager and energy features are extracted from IMFs. These extracted features are ranked using Chernoff Bound and Bhattacharyya Distance (CBBD), Kullback-Leibler Divergence (KLD), Fuzzy-minimum Redundancy Maximum Relevance (FmRMR), Wilcoxon, Receiver Operating Characteristics Curve (ROC) and t-test methods. Further, these ranked features are fed to Support Vector Machine (SVM) classifier to classify normal and abnormal (DR, AMD and glaucoma) classes. The performance of the proposed eye screening system is evaluated using 800 (Normal=400 and Abnormal=400) digital fundus images and 10-fold cross validation method. Our proposed system automatically identifies normal and abnormal classes with an average accuracy of 88.63%, sensitivity of 86.25% and specificity of 91% using 17 optimal features ranked using CBBD and SVM-Radial Basis Function (RBF) classifier. Moreover, a novel Retinal Risk Index (RRI) is developed using two significant features to distinguish two classes using single number. Such a system helps to reduce eye

  1. A bi-dimensional genome scan for prolificacy traits in pigs shows the existence of multiple epistatic QTL

    PubMed Central

    2009-01-01

    Background Prolificacy is the most important trait influencing the reproductive efficiency of pig production systems. The low heritability and sex-limited expression of prolificacy have hindered to some extent the improvement of this trait through artificial selection. Moreover, the relative contributions of additive, dominant and epistatic QTL to the genetic variance of pig prolificacy remain to be defined. In this work, we have undertaken this issue by performing one-dimensional and bi-dimensional genome scans for number of piglets born alive (NBA) and total number of piglets born (TNB) in a three generation Iberian by Meishan F2 intercross. Results The one-dimensional genome scan for NBA and TNB revealed the existence of two genome-wide highly significant QTL located on SSC13 (P < 0.001) and SSC17 (P < 0.01) with effects on both traits. This relative paucity of significant results contrasted very strongly with the wide array of highly significant epistatic QTL that emerged in the bi-dimensional genome-wide scan analysis. As much as 18 epistatic QTL were found for NBA (four at P < 0.01 and five at P < 0.05) and TNB (three at P < 0.01 and six at P < 0.05), respectively. These epistatic QTL were distributed in multiple genomic regions, which covered 13 of the 18 pig autosomes, and they had small individual effects that ranged between 3 to 4% of the phenotypic variance. Different patterns of interactions (a × a, a × d, d × a and d × d) were found amongst the epistatic QTL pairs identified in the current work. Conclusions The complex inheritance of prolificacy traits in pigs has been evidenced by identifying multiple additive (SSC13 and SSC17), dominant and epistatic QTL in an Iberian × Meishan F2 intercross. Our results demonstrate that a significant fraction of the phenotypic variance of swine prolificacy traits can be attributed to first-order gene-by-gene interactions emphasizing that the phenotypic effects of alleles might be strongly modulated by the

  2. Initial adaptation testing of the bidimensionally self-adapting wall of the French T2 wind tunnel, around a three-dimensional object

    NASA Technical Reports Server (NTRS)

    Archambaud, J. P.; Dor, J. B.; Mignosi, A.; Lamarche, L.

    1986-01-01

    The test series was carried out at ONERA/CERT at the T2 wind tunnel in September 1984. The objective of this series was to minimize wall interference through a bidimensional adaptation around the models, inducing tridimensional flows. For this, three different models were used, measuring either the pressures or the forces and moment of pitch (balance). The adaptation was derived from a correction computation in the compressible axisymmetric tridimensional.

  3. On the bi-dimensional variational decomposition applied to nonstationary vibration signals for rolling bearing crack detection in coal cutters

    NASA Astrophysics Data System (ADS)

    Jiang, Yu; Li, Zhixiong; Zhang, Chao; Hu, Chao; Peng, Z.

    2016-06-01

    This work aims to detect rolling bearing cracks using a variational approach. An original method that appropriately incorporates bi-dimensional variational mode decomposition (BVMD) into discriminant diffusion maps (DDM) is proposed to analyze the nonstationary vibration signals recorded from the cracked rolling bearings in coal cutters. The advantage of this variational decomposition based diffusion map (VDDM) method in comparison to the current DDM is that the intrinsic vibration mode of the crack can be filtered into a limited bandwidth in the frequency domain with an estimated central frequency, thus discarding the interference signal components in the vibration signals and significantly improving the crack detection performance. In addition, the VDDM is able to simultaneously process two-channel sensor signals to reduce information leakage. Experimental validation using rolling bearing crack vibration signals demonstrates that the VDDM separated the raw signals into four intrinsic modes, including one roller vibration mode, one roller cage vibration mode, one inner race vibration mode, and one outer race vibration mode. Hence, reliable fault features were extracted from the outer race vibration mode, and satisfactory crack identification performance was achieved. The comparison between the proposed VDDM and existing approaches indicated that the VDDM method was more efficient and reliable for crack detection in coal cutter rolling bearings. As an effective catalyst for rolling bearing crack detection, this newly proposed method is useful for practical applications.

  4. Nonpreemptive run-time scheduling issues on a multitasked, multiprogrammed multiprocessor with dependencies, bidimensional tasks, folding and dynamic graphs

    SciTech Connect

    Miller, Allan Ray

    1987-05-01

    Increases in high speed hardware have mandated studies in software techniques to exploit the parallel capabilities. This thesis examines the effects a run-time scheduler has on a multiprocessor. The model consists of directed, acyclic graphs, generated from serial FORTRAN benchmark programs by the parallel compiler Parafrase. A multitasked, multiprogrammed environment is created. Dependencies are generated by the compiler. Tasks are bidimensional, i.e., they may specify both time and processor requests. Processor requests may be folded into execution time by the scheduler. The graphs may arrive at arbitrary time intervals. The general case is NP-hard, thus, a variety of heuristics are examined by a simulator. Multiprogramming demonstrates a greater need for a run-time scheduler than does monoprogramming for a variety of reasons, e.g., greater stress on the processors, a larger number of independent control paths, more variety in the task parameters, etc. The dynamic critical path series of algorithms perform well. Dynamic critical volume did not add much. Unfortunately, dynamic critical path maximizes turnaround time as well as throughput. Two schedulers are presented which balance throughput and turnaround time. The first requires classification of jobs by type; the second requires selection of a ratio value which is dependent upon system parameters. 45 refs., 19 figs., 20 tabs.

  5. A bi-dimensional index for the selective assessment of myoelectric manifestations of peripheral and central muscle fatigue.

    PubMed

    Mesin, Luca; Cescon, Corrado; Gazzoni, Marco; Merletti, Roberto; Rainoldi, Alberto

    2009-10-01

    Two physiological factors are assumed in this paper to mainly determine the myoelectric manifestations of fatigue: (1) the decrease of the conduction velocity (CV) of motor unit action potentials (MUAP) (peripheral fatigue), and (2) the increase of MU synchronization by the central nervous system (central fatigue). To describe separately the peripheral and central components of the myoelectric manifestations of fatigue, we investigated the following indexes: (1) mean spectral frequency - MNF, (2) median spectral frequency - MDF, (3) root mean square - RMS, (4) average rectified value - ARV, (5) estimation of muscle fiber conduction velocity - ECV, (6) percentage of determinism - %DET, (7) spectral indexes defined as the ratio between signal spectral moments - FI(k), (8) MNF estimated by autoregressive analysis - MNF(AR), (9) MNF estimated by Choi-Williams time-frequency representation - MNF(CWD), (10) MNF estimated by continuous wavelet transform - MNF(CWT), (11) signal entropy - S, (12) fractal dimension - FD. The indexes were tested with a set of synthetic EMG signals, with different CV distribution and level of MU synchronization. The indexes were calculated on epochs of 0.5s. It was observed that ECV is uncorrelated with the level of simulated synchronization (promising index of peripheral fatigue). On the other hand FD was the index least affected by CV changes and most related to the level of synchronism (promising index of central fatigue). A representative application to some experimental signals from vastus lateralis muscle during an isometric endurance test supported the results of the simulations. The vector (ECV, FD) is suggested to provide selective indications of peripheral and central fatigue. The description of EMG fatigue by a bi-dimensional vector opens new perspectives in the assessment of muscle properties, with potential application in both clinical and sport sciences. PMID:18824375

  6. Simulating the interaction of the heliosphere with the local interstellar medium: MHD results from a finite volume approach, first bidimensional results

    NASA Technical Reports Server (NTRS)

    Chanteur, G.; Khanfir, R.

    1995-01-01

    We have designed a full compressible MHD code working on unstructured meshes in order to be able to compute accurately sharp structures embedded in large scale simulations. The code is based on a finite volume method making use of a kinetic flux splitting. A bidimensional version of the code has been used to simulate the interaction of a moving interstellar medium, magnetized or unmagnetized with a rotating and magnetized heliopspheric plasma source. Being aware that these computations are not realistic due to the restriction to two dimensions, we present it to demonstrate the ability of this new code to handle this problem. An axisymetric version, now under development, will be operational in a few months. Ultimately we plan to run a full 3d version.

  7. Thermal image enhancement using bi-dimensional empirical mode decomposition in combination with relevance vector machine for rotating machinery fault diagnosis

    NASA Astrophysics Data System (ADS)

    Tran, Van Tung; Yang, Bo-Suk; Gu, Fengshou; Ball, Andrew

    2013-07-01

    In this study, a novel fault diagnosis system for rotating machinery using thermal imaging is proposed. This system consists of bi-dimensional empirical mode decomposition (BEMD) for image enhancement, a generalized discriminant analysis (GDA) for feature reduction, and a relevance vector machine (RVM) for fault classification. Firstly, the thermal image obtained from machine conditions is decomposed into intrinsic mode functions (IMFs) by using BEMD. At each decomposed level, the IMF is expanded and fused with the residue by gray-scale transformation and principal component analysis fusion technique, respectively. The enhanced image is then formed by the improved IMFs in reconstruction process. Subsequently, feature extraction is applied for the enhanced images to obtain histogram features which characterize the thermal image and contain useful information for diagnosis. The high dimensionality of the achieved feature set can be reduced by GDA implementation. Moreover, GDA also assists in the increase of the feature cluster separation. Finally, the diagnostic results are performed by RVM. The proposed system is applied and validated with the thermal images of a fault simulator. A comparative study of the classification results obtained from RVM, support vector machines, and adaptive neuro-fuzzy inference system is also performed to appraise the accuracy of these models. The results show that the proposed diagnosis system is capable of improving the classification accuracy and efficiently assisting in rotating machinery fault diagnosis.

  8. Lie algebraic approach to the time-dependent quantum general harmonic oscillator and the bi-dimensional charged particle in time-dependent electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Ibarra-Sierra, V. G.; Sandoval-Santana, J. C.; Cardoso, J. L.; Kunold, A.

    2015-11-01

    We discuss the one-dimensional, time-dependent general quadratic Hamiltonian and the bi-dimensional charged particle in time-dependent electromagnetic fields through the Lie algebraic approach. Such method consists in finding a set of generators that form a closed Lie algebra in terms of which it is possible to express a quantum Hamiltonian and therefore the evolution operator. The evolution operator is then the starting point to obtain the propagator as well as the explicit form of the Heisenberg picture position and momentum operators. First, the set of generators forming a closed Lie algebra is identified for the general quadratic Hamiltonian. This algebra is later extended to study the Hamiltonian of a charged particle in electromagnetic fields exploiting the similarities between the terms of these two Hamiltonians. These results are applied to the solution of five different examples: the linear potential which is used to introduce the Lie algebraic method, a radio frequency ion trap, a Kanai-Caldirola-like forced harmonic oscillator, a charged particle in a time dependent magnetic field, and a charged particle in constant magnetic field and oscillating electric field. In particular we present exact analytical expressions that are fitting for the study of a rotating quadrupole field ion trap and magneto-transport in two-dimensional semiconductor heterostructures illuminated by microwave radiation. In these examples we show that this powerful method is suitable to treat quadratic Hamiltonians with time dependent coefficients quite efficiently yielding closed analytical expressions for the propagator and the Heisenberg picture position and momentum operators.

  9. Bidimensional Particle-In-Cell simulations for laser-driven proton acceleration using ultra-short, ultra-high contrast laser

    SciTech Connect

    Scisciò, M.; Palumbo, L.; D'Humières, E.; Fourmaux, S.; Kieffer, J. C.; Antici, P.

    2014-12-15

    In this paper, we report on bi-dimensional Particle-In-Cell simulations performed in order to reproduce the laser-driven proton acceleration obtained when a commercial 200 TW Ti:Sa Laser hits a solid target. The laser-to prepulse contrast was enhanced using plasma mirrors yielding to a main-to-prepulse contrast of ∼10{sup 12}. We varied the pulse duration from 30 fs to 500 fs and the target thickness from 30 nm to several tens of μm. The on-target laser energy was up to 1.8 J leading to an intensity in excess of 10{sup 20 }W cm{sup −2}. A comparison between numerical and existing experimental data [S. Fourmaux et al., Phys. Plasmas 20, 013110 (2013)] is performed, showing a good agreement between experimental results and simulations which confirms that for ultra-thin targets there is an optimum expansion regime. This regime depends on the target thickness and on the laser intensity: if the target is too expanded, the laser travels through the target without being able to deposit its energy within the target. If the target is not sufficiently expanded, the laser energy is reflected by the target. It is important to note that maximum proton energies are reached at longer pulse durations (in the 100 fs regime) than what is currently the best compression pulse length for this type of lasers (typically 20–30 fs). This duration, around 50–100 fs, can be considered a minimum energy transfer time between hot electrons to ions during the considered acceleration process.

  10. Blood flow volume of uterine arteries in human pregnancies determined using 3D and bi-dimensional imaging, angio-Doppler, and fluid-dynamic modeling.

    PubMed

    Rigano, S; Ferrazzi, E; Boito, S; Pennati, G; Padoan, A; Galan, H

    2010-01-01

    The primary aim of this pilot study was to study uterine artery (UtA) blood flow volume in uneventful human pregnancies delivered at term, at mid and late gestation by means of 3D and bi-dimensional ultrasound imaging with angio-Doppler combined with fluid-dynamic modeling. Secondary aims were to correlate flow volume to placental site and to UtA Pulsatility Index (PI). Women with singleton, low-risk pregnancies were examined at mid and late gestation. The structure and course of the uterine artery (UtA) was studied in each patient by means of 3D-angio-Doppler and included vessel diameter D, blood flow velocity and PI (measured along the UtA). Fetal weight estimation and placental insertion site were assessed by ultrasound. A robust fluid-dynamic modeling was applied to calculate absolute flow and flow per unit fetal weight. Mean UtA diameter and blood flow velocity increased significantly (p < 0.0001) from mid-gestation to late gestation from 2.6 mm and 67.5 cm/s, to 3.0 mm and 85.3 cm/s, respectively, yielding an increasing absolute flow troughout gestation. h coefficient, derived by fluid-dynamic modeling to calculate mean velocity, increased significantly from 0.52 at mid-gestation to 0.57 at late gestation. UtA blood flow volume ml/min/kg-fetal weight was significantly higher at mid-gestation than at late gestation (535 ml/min/kg vs 193 ml/min/kg; p < 0.0001). In cases with strictly lateral placentas the ipsilateral UtA accommodates at mid and late gestation 63% and 67% of the total UtA flow. In central placentas UtA flow was evenly distributed between the two vessels. An inverse correlation was observed between PI and blood flow volume ml/min/kg (Pearson's coefficient r = -0.54). Our work confirms the technological and methodological limitations in the measurement of uterine artery blood flow. However, Doppler measurements supported by three-dimensional angio imaging of the uterine vessel, high resolution imaging and diameter measurement, and a robust

  11. Combined effect of tobacco smoking and alcohol drinking in the risk of head and neck cancers: a re-analysis of case-control studies using bi-dimensional spline models.

    PubMed

    Dal Maso, Luigino; Torelli, Nicola; Biancotto, Elisa; Di Maso, Matteo; Gini, Andrea; Franchin, Gianni; Levi, Fabio; La Vecchia, Carlo; Serraino, Diego; Polesel, Jerry

    2016-04-01

    The synergistic effect of tobacco smoking and alcohol consumption on the risk of head and neck cancers has been mainly investigated as a cross-product of categorical exposure, thus leading to loss of information. We propose a bi-dimensional logistic spline model to investigate the interacting dose-response relationship of two continuous exposures (i.e., ethanol intake and tobacco smoking) on the risk of head and neck cancers, representing results through three-dimensional graphs. This model was applied to a pool of hospital-based case-control studies on head and neck cancers conducted in Italy and in the Vaud Swiss Canton between 1982 and 2000, including 1569 cases and 3147 controls. Among never drinkers and for all levels of ethanol intake, the risk of head and neck cancers steeply increased with increasing smoking intensity, starting from 1 cigarette/day. The risk associated to ethanol intake increased with incrementing exposure among smokers, and a threshold effect at approximately 50 g/day emerged among never smokers. Compared to abstainers from both tobacco and alcohol consumption, the combined exposure to ethanol and/or cigarettes led to a steep increase of cancer risk up to a 35-fold higher risk (95 % confidence interval 27.30-43.61) among people consuming 84 g/day of ethanol and 10 cigarettes/day. The highest risk was observed at the highest levels of alcohol and tobacco consumption. Our findings confirmed a combined effect of tobacco smoking and alcohol drinking on head and neck cancers risk, providing evidence that bi-dimensional spline models could be a feasible and flexible method to explore the pattern of risks associated to two interacting continuous-exposure variables. PMID:25855002

  12. A simple controller for bidimensional image detectors

    NASA Astrophysics Data System (ADS)

    Angeles, F.; Martínez, L. A.

    2012-07-01

    The increasing use of many and different kind of light detectors to acquire, monitor and control various aspects of the observation imposes the need to standardize the acquisition and processing of images and data. While scientific image acquisition systems usually include a complex controller, some less demanding subsystems require the development of electronics and software to read the image. Most of the times these image detectors are rather small and high speed is of no concern, so controllers need not to be fast; take for instance a telescope guider. With these directives in mind, in this work we present a very simple image acquisition system based on a Texas Instruments microcontroller of the family MSP430 and a serial static memory as a standard instrumentation starting for small image acquisition controllers.

  13. Bidimensional silicon dosimeter: Development and characterization

    NASA Astrophysics Data System (ADS)

    Talamonti, C.; Bruzzi, M.; Marrazzo, L.; Menichelli, D.; Scaringella, M.; Bucciolini, M.

    2011-12-01

    Clinical dosimetry in radiotherapy is a well known matter but high conformal radiotherapy modalities (Intensity Modulated Radiation Therapy (IMRT), stereotactic treatments with photons and protons, Intensity Modulated Proton Therapy (IMPT)) possess problems due to small radiation fields with high dose gradients, variation in space and time of the dose rate and variation in space and time of the beam energy spectrum. A modular dosimetric detector, adequate for 2D pre-treatment dose verifications, has been developed in the framework of the European Integrated project MAESTRO. The detector is a monolithic segmented sensor obtained by n-type implantation on a 50 μthick epitaxial silicon p-type layer; this is later used to guarantee improved radiation hardness of the device against the accumulated dose. The detector is composed of a matrix of 21×21 pixels with a size of 2×2 mm 2 each and a 3 mm center-to-center distance. A full dosimetric characterization of the detector was performed with photon and proton beams and with gammas from a 60Co unit. Results have been compared with those obtained with a Farmer and a CC13 Scanditronix/Welhoffer ion chamber as well as with the silicon matrix MapCHECK™. The first application of the MAESTRO prototype in the dosimetric verification of a clinical IMRT field is also reported. Results show that our modular detector represents a valuable tool for quality assurance in IMRT dose delivery and for high precision radiotherapy techniques.

  14. Ab initio simulations of pseudomorphic silicene and germanene bidimensional heterostructures

    NASA Astrophysics Data System (ADS)

    Debernardi, Alberto; Marchetti, Luigi

    2016-06-01

    Among the novel two-dimensional (2D) materials, silicene and germanene, which are two honeycomb crystal structures composed of a monolayer of Si and Ge, respectively, have attracted the attention of material scientists because they combine the advantages of the new 2D ultimate-scaled electronics with their compatibility with industrial processes presently based on Si and Ge. We envisage pseudomorphic lateral heterostructures based on ribbons of silicene and germanene, which are the 2D analogs of conventional 3D Si/Ge superlattices and quantum wells. In spite of the considerable lattice mismatch (˜4 % ) between free-standing silicene and germanene, our ab initio simulations predict that, considering striped 2D lateral heterostructures made by alternating silicene and germanene ribbons of constant width, the silicene/germanene junction remains pseudomorphic—i.e., it maintains lattice-matched edges—up to critical ribbon widths that can reach some tens of nanometers. Such critical widths are one order of magnitude larger than the critical thickness measured in 3D pseudomorphic Si/Ge heterostructures and the resolution of state-of-the-art lithography, thus enabling the possibility of lithography patterned silicene/germanene junctions. We computed how the strain produced by the pseudomorphic growth modifies the crystal structure and electronic bands of the ribbons, providing a mechanism for band-structure engineering. Our results pave the way for lithography patterned lateral heterostructures that can serve as the building blocks of novel 2D electronics.

  15. Wideband image demodulation via bi-dimensional multirate frequency transformations.

    PubMed

    Liu, Wenjing; Santhanam, Balu

    2016-09-01

    Existing image demodulation approaches based on the two-dimensional (2D) multicomponent AM-FM model assume narrowband components that can be demodulated using energy operators, Hilbert transforms, or the monogenic image approaches. However, if the FM components are wideband, then these demodulation approaches incur significant errors. Recent work by the authors extended wideband FM demodulation in one dimension to accommodate large conversion factors using multirate frequency transformations. In this paper, we extend the multirate frequency transformations technique developed for one-dimensional signals to 2D and images in conjunction with a recently proposed 2D higher-order energy demodulation approach. This extension is applied to both synthetic and real images to demonstrate the efficacy of the approach. PMID:27607487

  16. Nonlinear bidimensional evolution of ion beam driven electrostatic instabilities in the auroral region

    NASA Astrophysics Data System (ADS)

    Mottez, Fabrice; Chanteur, Gerard

    1991-12-01

    A 2D (in configuration space), 3D (in velocity space) electrostatic explicit particle code is used to investigate the interaction between an ion beam flowing along the magnetic field and a highly magnetized plasma. The beam drift velocity Vdi is larger than Vte, the electron thermal velocity, and much larger than the thermal velocities of the core and beam ions. Two instabilities are found to develop. First, the interaction between the ion beam and electrons leads to the rapid growth of parallel modes and to the fast diffusion of electrons along the magnetic field, predominantly in the ion beam direction. This ion-electron instability is rapidly quenched by electron heating. Second, and ion-ion instability develops, which involves oblique modes leading to a selective heating of ions in a direction oblique to B. It is shown that the heating via the electron-ion instability is a necessary step for the development of the ion-ion instability. Finally, it is shown that the nonlinear development of the ion-ion instability gives rise to purely perpendicular modes that are not linearly unstable.

  17. In situ growth and coalescence of He-filled bi-dimensional defects in Si by H supply

    NASA Astrophysics Data System (ADS)

    Vallet, M.; Barbot, J. F.; Oliviero, E.; Donnelly, S. E.; Hinks, J. A.; Beaufort, M. F.

    2014-06-01

    In this work, ion implantations with in situ transmission electron microscopy observations followed by different rates of temperature ramp were performed in (001)-Si to follow the evolution of He-plates under the influence of hydrogen. The JANNUS and MIAMI facilities were used to study the first stages of growth as well as the interactions between co-planar plates. Results showed that under a limited amount of H, the growth of He-plates resulting from a subcritical stress-corrosion mechanism can be fully described by the kinetic model of Johnson-Mehl-Avrami-Kolmogorov with effective activation energy of 0.9 eV. Elastic calculations showed that the sudden and non-isotropic coalescence of close He-plates occurs when the out-of-plane tensile stress between them is close to the yield strength of silicon. After hydrogen absorption, surface minimization of final structure occurs.

  18. Applying fuzzy bi-dimensional scenario-based model to the assessment of Mars mission architecture scenarios

    NASA Astrophysics Data System (ADS)

    Tavana, Madjid; Zandi, Faramak

    2012-02-01

    Sending man to Mars has been a long-held dream of humankind. NASA plans human planetary explorations using approaches that are technically feasible, have reasonable risks and have relatively low costs. This study presents a novel Multi-Attribute Decision Making (MADM) model for evaluating a range of potential mission scenarios for the human exploration of Mars. The three alternatives identified by the Mission Operations Directorate (MOD) at the Johnson Space Center (JSC) include split mission, combo lander and dual scenarios. The proposed framework subsumes the following key methods: first, the conjunction method is used to minimize the number of alternative mission scenarios; second, the Fuzzy Risk Failure Mode and Effects Analysis (RFMEA) is used to analyze the potential failure of the alternative scenarios; third, the fuzzy group Real Option Analysis (ROA) is used to estimate the expected costs and benefits of the alternative scenarios; and fourth, the fuzzy group permutation approach is used to select the optimal mission scenario. We present the results of a case study at NASA's Johnson Space center to demonstrate: (1) the complexity of mission scenario selection involving subjective and objective judgments provided by multiple space exploration experts; and (2) a systematic and structured method for aggregating quantitative and qualitative data concerning a large number of competing and conflicting mission events.

  19. In situ growth and coalescence of He-filled bi-dimensional defects in Si by H supply

    SciTech Connect

    Vallet, M.; Barbot, J. F. Beaufort, M. F.; Oliviero, E.; Donnelly, S. E.; Hinks, J. A.

    2014-06-14

    In this work, ion implantations with in situ transmission electron microscopy observations followed by different rates of temperature ramp were performed in (001)-Si to follow the evolution of He-plates under the influence of hydrogen. The JANNUS and MIAMI facilities were used to study the first stages of growth as well as the interactions between co-planar plates. Results showed that under a limited amount of H, the growth of He-plates resulting from a subcritical stress-corrosion mechanism can be fully described by the kinetic model of Johnson-Mehl-Avrami-Kolmogorov with effective activation energy of 0.9 eV. Elastic calculations showed that the sudden and non-isotropic coalescence of close He-plates occurs when the out-of-plane tensile stress between them is close to the yield strength of silicon. After hydrogen absorption, surface minimization of final structure occurs.

  20. Development of an offline bidimensional high-performance liquid chromatography method for analysis of stereospecific triacylglycerols in cocoa butter equivalents.

    PubMed

    Kadivar, Sheida; De Clercq, Nathalie; Nusantoro, Bangun Prajanto; Le, Thien Trung; Dewettinck, Koen

    2013-08-21

    Acyl migration is a serious problem in enzymatic modification of fats and oils, particularly in production of cocoa butter equivalent (CBE) through enzymatic acidolysis reaction, which leads to the formation of non-symmetrical triacylglycerols (TAGs) from symmetrical TAGs. Non-symmetrical TAGs may affect the physical properties of final products and are therefore often undesired. Consequently, an accurate method is needed to determine positional isomer TAGs during the production of CBE. A bidimentional high-performance liquid chromatography (HPLC) method with combination of non-aqueous reversed-phase HPLC and silver ion HPLC joining with an evaporative light scattering detector was successfully developed for the analysis of stereospecific TAGs. The best separation of positional isomer standards was obtained with a heptane/acetone mobile-phase gradient at 25 °C and 1 mL/min. The developed method was then used in multidimensional determination of the TAG positional isomers in fat and oil blends and successfully identified the TAGs and possible isomers in enzymatically acidolyzed CBE. PMID:23931630

  1. A Basic Positron Emission Tomography System Constructed to Locate a Radioactive Source in a Bi-dimensional Space.

    PubMed

    Montaño-Zetina, Luis Manuel; Villalobos-Mora, Omar

    2016-01-01

    A simple Positron Emission Tomography (PET) prototype has been constructed to fully characterize its basic working principles. The PET prototype was created by coupling plastic scintillator crystals to photomultipliers or PMT's which are placed at opposing positions to detect two gamma rays emitted from a radioactive source, of which is placed in the geometric center of the PET set-up. The prototype consists of four detectors placed geometrically in a 20 cm diameter circle, and a radioactive source in the center. By moving the radioactive source centimeters from the center the system one is able to detect the displacement by measuring the time of flight difference between any two PMT's and, with this information, the system can calculate the virtual position in a graphical interface. In this way, the prototype reproduces the main principles of a PET system. It is capable to determine the real position of the source with intervals of 4 cm in 2 lines of detection taking less than 2 min. PMID:26863081

  2. Chemical warfare agent detection in complex environments with comprehensive two-dimensional gas chromatography

    NASA Astrophysics Data System (ADS)

    Reichenbach, Stephen E.; Ni, Mingtian; Kottapalli, Visweswara; Visvanathan, Arvind; Ledford, Edward B., Jr.; Oostdijk, John; Trap, Henk C.

    2003-08-01

    Comprehensive two-dimensional gas chromatography (GCxGC) is an emerging technology for chemical separation that provides an order-of-magnitude increase in separation capacity over traditional gas chromatography. GCxGC separates chemical species with two capillary columns interfaced by two-stage thermal desorption. Because GCxGC is comprehensive and has high separation capacity, it can perform multiple traditional analytical methods with a single analysis. GCxGC has great potential for a wide variety of environmental sensing applications, including detection of chemical warfare agents (CWA) and other harmful chemicals. This paper demonstrates separation of nerve agents sarin and soman from a matrix of gasoline and diesel fuel. Using a combination of an initial column separating on the basis of boiling point and a second column separating on the basis of polarity, GCxGC clearly separates the nerve agents from the thousands of other chemicals in the sample. The GCxGC data is visualized, processed, and analyzed as a two-dimensional digital image using a software system for GCxGC image processing developed at the University of Nebraska - Lincoln.

  3. A comprehensive two-dimensional gas chromatography method for analyzing extractable petroleum hydrocarbons in water and soil.

    PubMed

    Seeley, Stacy K; Bandurski, Steven V; Brown, Robert G; McCurry, James D; Seeley, John V

    2007-01-01

    A flow-switching two-dimensional gas chromatography (GCxGC) apparatus has been constructed that can operate at temperatures as high as 340 degrees C. This system is employed to analyze complex hydrocarbon mixtures such as diesel fuel, gas-oil, motor oil, and petroleum contaminated environmental samples. The GCxGC system generates two-dimensional chromatograms with minimal overlap between the aliphatic and aromatic regions This allows these compound classes to be independently quantitated without prior fractionation. The GCxGC system is used to analyze extracts of spiked water samples, wastewater, and soil. The accuracy of the method is compared to that of the Massachusetts Extractable Petroleum Hydrocarbons (MA EPH) method. The GCxGC system generates a quantitative accuracy similar to the MA EPH method for the analysis of spiked water samples. The GCxGC method and the MA EPH method generate comparable levels of total hydrocarbons when wastewater is analyzed, but the GCxGC method detects a significantly higher aromatic content and lower aliphatic content. Both the GCxGC method and MA EPH method measure comparable levels of aromatics in the soil samples. PMID:18078573

  4. Filamentation of plasma in the auroral region by an ion-ion instability - A process for the formation of bidimensional potential structures

    NASA Astrophysics Data System (ADS)

    Mottez, F.; Chanteur, G.; Roux, A.

    1992-07-01

    The nonlinear behavior of electrostatic ion waves generated by an ion beam flowing through a thermal ion and electron background in a strongly magnetized plasma is investigated by means of a 2D, explicit, electrostatic particle code. To follow the nonlinear evolution of these ion waves, a long-lasting simulation is run with a large simulation grid: 128 x 512 lambda(d). Beam ions are shown to generate oblique waves. The nonlinear beatings between these oblique waves produce purely transverse waves, which leads to a strong modulation of the density and of the electric potential in a direction transverse to the magnetic field. The transverse scale of these essentially field-aligned filaments is 10 rho(i), where rho(i) is the ion Larmor radius of beam ions. Within these filaments, relatively stable field-aligned density and potential structures develop. Unlike the potential structures that develop in a two-component plasma with downgoing electrons, these structures move upward.

  5. Exploring the effects of high-velocity flows in abundance determinations in H II regions: bidimensional spectroscopy of HH 204 in the Orion nebula

    NASA Astrophysics Data System (ADS)

    Núñez-Díaz, M.; Mesa-Delgado, A.; Esteban, C.; López-Martín, L.; García-Rojas, J.; Luridiana, V.

    2012-04-01

    We present results from integral field optical spectroscopy with the Potsdam Multi-Aperture Spectrograph of the Herbig-Haro (HH) object HH 204, with a spatial sampling of 1 × 1 arcsec2. We have obtained maps of different emission lines, physical conditions and ionic abundances from collisionally excited lines. The ionization structure of the object indicates that the head of the bow shock is optically thick and has developed a trapped ionization front. The density at the head is at least five times larger than in the background ionized gas. We discover a narrow arc of high Te([N II]) values delineating the southeast edge of the head. The temperature in this zone is about 1000 K higher than in the rest of the field and should correspond to a shock-heated zone at the leading working surface of the gas flow. This is the first time this kind of feature is observed in a photoionized HH object. We find that the O+ and O abundance maps show anomalous values at separate areas of the bow shock probably due to: (a) overestimation of the collisional de-excitation effects of the [O II] lines in the compressed gas at the head of the bow shock, and (b) the use of a too high Te([N II]) at the area of the leading working surface of the flow.

  6. Evaluation of a Kalman-based block matching method to assess the bi-dimensional motion of the carotid artery wall in B-mode ultrasound sequences.

    PubMed

    Zahnd, Guillaume; Orkisz, Maciej; Sérusclat, André; Moulin, Philippe; Vray, Didier

    2013-07-01

    We aim at investigating arterial diseases at early stage, by assessing the longitudinal (i.e. in the same direction as the blood flow) motion of the intima-media complex. This recently evidenced phenomenon has been shown to provide relevant and complementary information about vascular health. Our method assesses the longitudinal and radial motion from clinical in vivo B-mode ultrasound sequences. To estimate the trajectory of a selected point during the cardiac cycle, we introduce a block matching method that involves a temporal update of the reference block using a pixel-wise Kalman filter. The filter uses the initial gray-level of the pixel as control signal to avoid divergence due to cumulating errors. The block and search-window sizes are adapted to the tissue of interest. The method was evaluated on image sequences of the common carotid artery, acquired in 57 healthy volunteers and in 25 patients at high cardiovascular risk. Reference trajectories were generated for each sequence by averaging the tracings performed by three observers. Six different computerized techniques were also compared to our method. With a pixel size of 30 μm, the average absolute motion estimation errors were 84 ± 107 μm and 20 ± 19 μm for the longitudinal and radial directions, respectively. This accuracy was of the same order of magnitude as the inter- and intra-observers variability, and smaller than for the other methods. The estimated longitudinal motion amplitude was significantly reduced in at-risk patients compared with healthy volunteers (408 ± 281 μm vs. 643 ± 274 μm, p<0.0001). Our method can constitute a reliable and time-saving technique to investigate the arterial stiffness in clinical studies, in the objective to detect early-stage atherosclerosis. PMID:23612497

  7. Descripción de la zona de alta difusión en un modelo bidimensional para hojas de corriente

    NASA Astrophysics Data System (ADS)

    Montero, M. F.; Paola, C. A.; Platzeck, A. M.

    Los modelos bidimensionales para describir hojas de corriente de alta simetría no suministran una descripción detallada de las regiones donde la difusión es considerablemente importante. Tal es el caso de los modelos desarrollados en la década del '60 por Sweet, Parker, Petschek y Sonnerup. En esta comunicación presentamos una solución de las ecuaciones MHD en el entorno del origen, construyendo series bidimensionales para todas las magnitudes físicas involucradas. Valiéndonos de la alta simetría y de las características del problema, logramos reducir el número de coeficientes a calcular. Utilizamos un programa autoconsistente para extender el cálculo a regiones vecinas con difusión moderada o despreciable.

  8. Application of comprehensive two-dimensional gas chromatography for the assessment of oil contaminated soils.

    PubMed

    Van De Weghe, Hendrik; Vanermen, Guido; Gemoets, Johan; Lookman, Richard; Bertels, Diane

    2006-12-22

    A crucial step in the remediation of oil contaminated soils is the characterization of the pollution. Information on the chemical composition is used to assess the toxicity (and thus the need for remediation) and to determine the most appropriate technology for treatment. Mostly these analyses are carried out in routine environmental laboratories using gas chromatography with flame ionization detection (GC/FID) based on a protocol developed by the Total Petroleum Hydrocarbon Criteria Working Group (TPHCWG). In the present study, an alternative method was developed using comprehensive two-dimensional gas chromatography (GCXGC) with FID. Sample preparation was limited to pressurized liquid extraction (PLE), and the analysis was carried out on a commercially available instrument with a conventional column combination (RTX-1/BPX50) and with standard chromatographic software. Compared to the TPH method, the group-types in the GCXGC analysis are chemically better defined and more specific information is obtained especially for the (toxicologically important) aromatic hydrocarbon fraction. Preliminary results indicate that higher recoveries and lower RSDs are obtained with GCXGC, probably because of the less complex sample preparation. Furthermore a data processing method was developed to generate TPH results from GCXGC data; the volatility distribution profiles compared very well with conventional TPH data. The possibility of extracting physicochemical properties directly from the GCXGC chromatogram was briefly explored, but software limitations hindered this promising application. PMID:17055525

  9. Biomark/Organic Analysis with Time-of-Flight Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Waite, J. Hunter, Jr.

    2004-01-01

    The concept of a Comprehensive 2-Dimensional Gas Chromatography coupled with Time-of-Flight Mass Spectrometry (GCxGC-TOWS) for the analysis of organic compounds has been proven with commercially available instrumentation (LECO Corp). The performance of a GCxGC instrument has been characterized in various stages using two independent breadboard systems. The GCxGC separation systems, including the thermal modulator, have been miniaturized to the size of a benchtop configuration. One breadboard system employs a Flame Ionization Detector (FID), whereas the second breadboard system employs a Time-of-Fight mass spectrometer (TOFWS) as a detection system.

  10. "Heart-cut" bidimensional achiral-chiral liquid chromatography applied to the evaluation of stereoselective metabolism, in vivo biological activity and brain response to chiral drug candidates targeting the central nervous system.

    PubMed

    Battisti, Umberto M; Citti, Cinzia; Larini, Martina; Ciccarella, Giuseppe; Stasiak, Natalia; Troisi, Luigino; Braghiroli, Daniela; Parenti, Carlo; Zoli, Michele; Cannazza, Giuseppe

    2016-04-22

    A "heart-cut" two-dimensional achiral-chiral liquid chromatography triple-quadrupole mass spectrometry method (LC-LC-MS/MS) was developed and coupled to in vivo cerebral microdialysis to evaluate the brain response to the chiral compound (±)-7-chloro-5-(3-furanyl)-3-methyl-3,4-dihydro-2H-1,2,4-benzothiadiazine-1,1-dioxide ((±)-1), a potent positive allosteric modulator (PAM) of AMPA receptor. The method was successfully employed to evaluate also its stereoselective metabolism and in vitro biological activity. In particular, the LC achiral method developed, employs a pentafluorinated silica based column (Discovery HS-F5) to separate dopamine, acetylcholine, serotonin, (±)-1 and its two hepatic metabolites. In the "heart-cut" two-dimension achiral-chiral configuration, (±)-1 and (±)-1-d4 eluted from the achiral column (1st dimension), were transferred to a polysaccharide-based chiral column (2nd dimension, Chiralcel OD-RH) by using an automatic six-port valve. Single enantiomers of (±)-1 were separated and detected using electrospray positive ionization mode and quantified in selected reaction monitoring mode. The method was validated and showed good performance in terms of linearity, accuracy and precision. The new method employed showed several possible applications in the evaluation of: (a) brain response to neuroactive compounds by measuring variations in the brain extracellular levels of selected neurotransmitters and other biomarkers; (b) blood brain barrier penetration of drug candidates by measuring the free concentration of the drug in selected brain areas; (c) the presence of drug metabolites in the brain extracellular fluid that could prove very useful during drug discovery; (d) a possible stereoselective metabolization or blood brain barrier stereoselective crossing of chiral drugs. Finally, compared to the methods reported in the literature, this technique avoids the necessity of euthanizing an animal at each time point to measure drug concentration in whole brain tissue and provides continuous monitoring of extracellular concentrations of single chiral drug enantiomers along with its metabolites in specific brain regions at each selected time point for a desired period by using a single animal. PMID:27020886

  11. Iterative adaption of the bidimensional wall of the French T2 wind tunnel around a C5 axisymmetrical model: Infinite variation of the Mach number at zero incidence and a test at increased incidence

    NASA Technical Reports Server (NTRS)

    Archambaud, J. P.; Dor, J. B.; Payry, M. J.; Lamarche, L.

    1986-01-01

    The top and bottom two-dimensional walls of the T2 wind tunnel are adapted through an iterative process. The adaptation calculation takes into account the flow three-dimensionally. This method makes it possible to start with any shape of walls. The tests were performed with a C5 axisymmetric model at ambient temperature. Comparisons are made with the results of a true three-dimensional adaptation.

  12. Programmed automation of modulator cold jet flow for comprehensive two-dimensional gas chromatographic analysis of vacuum gas oils.

    PubMed

    Rathbun, Wayne

    2007-01-01

    A method is described for automating the regulation of cold jet flow of a comprehensive two-dimensional gas chromatograph (GCxGC) configured with flame ionization detection. This new capability enables the routine automated separation, identification, and quantitation of hydrocarbon types in petroleum fractions extending into the vacuum gas oil (VGO) range (IBP-540 degrees C). Chromatographic data acquisition software is programmed to precisely change the rate of flow from the cold jet of a nitrogen cooled loop modulator of a GCxGC instrument during sample analysis. This provides for the proper modulation of sample compounds across a wider boiling range. The boiling point distribution of the GCxGC separation is shown to be consistent with high temperature simulated distillation results indicating recovery of higher boiling semi-volatile VGO sample components. GCxGC configured with time-of-flight mass spectrometry is used to determine the molecular identity of individual sample components and boundaries of different molecular types. PMID:18078570

  13. A procedure for comprehensive two-dimensional gas chromatography retention time locked dual detection.

    PubMed

    Mommers, John; Ritzen, Erik; Dutriez, Thomas; van der Wal, Sjoerd

    2016-08-26

    In this paper, a novel, and easy to perform, retention time locking procedure for locking primary and secondary retention times of detector signals in comprehensive two-dimensional gas chromatography (GCxGC) dual-detection is proposed and its advantages are demonstrated and discussed. The dual detection retention time locking procedure is a 2-step process for a GCxGC system in which the effluent of the primary column is split, by using a pressure regulated splitter, towards the GCxGC modulator using two identical secondary GC columns of which one is installed in the main GC oven and the other is installed in a secondary GC oven. The first step of the locking procedure is to minimize the secondary retention time difference between both detectors of a compound, which has a retention factor (k) close to 0. This is done by stepwise altering the effective secondary column length, simply by sliding the secondary column, which is installed in the main oven, forwards or backwards through the modulator. The second step is to minimize the secondary retention time difference of a compound which has a significant retention in both dimensions. This is done by stepwise altering the secondary oven temperature rate. This locking procedure was successfully demonstrated for the analysis of a diesel sample by GCxGC coupled to a time of flight mass spectrometer (TOFMS) and a nitrogen chemiluminescence detector (NCD) and by GCxGC coupled to a TOFMS and a flame ionization detector (FID). For all compounds the average absolute secondary retention time differences between the NCD or the FID and the TOFMS detectors were 0.03, and 0.07s, respectively, which are significantly less than the average peak widths at half heights, which was 0.2s. PMID:27466154

  14. Optimization of separation and detection conditions for the multiresidue analysis of pesticides in grapes by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry.

    PubMed

    Banerjee, Kaushik; Patil, Sangram H; Dasgupta, Soma; Oulkar, Dasharath P; Patil, Shubhangi B; Savant, Rahul; Adsule, Pandurang G

    2008-05-01

    A comprehensive GCxGC-TOFMS method was optimized for multiresidue analysis of pesticides using a combination of a non-polar (RTX-5MS, 10 m x 0.18 mm x 0.2 microm) and a polar capillary column (TR-50MS, 1 m x 0.1 mm x 0.1 microm), connected in series through a dual stage thermal modulator. The method resolved the co-elution problems as observed in full scan one-dimensional GC-MS analysis and allowed chromatographic separation of 51 pesticides within 24 min run time with library-searchable mass spectrometric confirmation. Four pesticides, viz. chlorpyrifos-methyl, vinclozoline, parathion-methyl and heptachlor could be baseline separated on GCxGC, which were otherwise closely eluting and interfering each other's detection in 1D GC-MS run. Similarly, it could be possible to separate myclobutanil, buprofezin, flusilazole and oxyfluorfen on GCxGC. Although in 1D GC-MS, these closely eluting compounds could be identified through deconvolution algorithm and 'peak-find' option of the Chromatof software but the spectral purity significantly improved on GCxGC analysis. Thorough optimization was accomplished for the oven temperature programming, ion source temperature and GCxGC parameters like modulation period, duration of hot pulses, modulation-offset temperature, acquisition rate, etc. to achieve best possible separation of the test compounds. The limit of detection significantly improved by 2-12 times on GCxGC-TOFMS against GC-TOFMS because of sharper and narrower peak shapes. The method was tested for grape matrix after preparing the samples using previously described method and recoveries of the entire test pesticides were within 70-110% at 10 ng/g level of fortification. GCxGC-TOFMS was found to be an excellent technique for library-based screening of pesticides with high accuracy and sensitivity. PMID:18371973

  15. Characterisation of dense non-aqueous phase liquids of coal tar using comprehensive two-dimensional gas chromatography coupled with time of flight mass spectrometry.

    NASA Astrophysics Data System (ADS)

    Gauchotte-Lindsay, Caroline; McGregor, Laura; Richards, Phil; Kerr, Stephanie; Glenn, Aliyssa; Thomas, Russell; Kalin, Robert

    2013-04-01

    Comprehensive two-dimensional gas chromatography (GCxGC) is a recently developed analytical technique in which two capillary columns with different stationary phases are placed in series enabling planar resolution of the analytes. The resolution power of GCxGC is one order of magnitude higher than that of one dimension gas chromatography. Because of its high resolution capacity, the use of GCxGC for complex environmental samples such as crude oils, petroleum derivatives and polychlorinated biphenyls mixtures has rapidly grown in recent years. We developed a one-step method for the forensic analysis of coal tar dense non-aqueous phase liquids (DNAPLs) from former manufactured gas plant (FMGP) sites. Coal tar is the by-product of the gasification of coal for heating and lighting and it is composed of thousands of organic and inorganic compounds. Before the boom of natural gases and oils, most towns and cities had one or several manufactured gas plants that have, in many cases, left a devastating environmental print due to coal tar contamination. The fate of coal tar DNAPLs, which can persist in the environment for more than a hundred years, is therefore of crucial interest. The presented analytical method consists of a unique clean-up/ extraction stage by pressurized liquid extraction and a single analysis of its organic chemical composition using GCxGC coupled with time of flight mass spectrometry (TOFMS). The chemical fingerprinting is further improved by derivatisation by N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) of the tar compounds containing -OH functions such as alcohols and carboxylic acids. We present here how, using the logical order of elution in GCxGC-TOFMS system, 1) the identification of never before observed -OH containing compounds is possible and 2) the isomeric selectivity of an oxidation reaction on a DNAPL sample can be revealed. Using samples collected at various FMGP sites, we demonstrate how this GCxGC method enables the simultaneous

  16. Assessing Acquiescence in Binary Responses: IRT-Related Item-Factor-Analytic Procedures

    ERIC Educational Resources Information Center

    Ferrando, Pere J.; Condon, Lorena

    2006-01-01

    This article proposes procedures for assessing acquiescence in a balanced set of binary personality items. These procedures are based on the bidimensional item-factor analysis model, which is an alternative parameterization of the bidimensional 2-parameter normal-ogive item response theory model. First the rationale and general approach are…

  17. A Framework for Describing Interlanguages in Multilingual Settings.

    ERIC Educational Resources Information Center

    Tenjoh-Okwen, Thomas

    1989-01-01

    Outlines a contrastive analysis model and a non-contrastive analysis model for studying interlanguage in strictly bilingual settings, and suggests a bidimensional framework, including both linguistic and curricular components, for studying interlanguage in multilingual settings. (21 references) (CB)

  18. Characterisation of biodegradation capacities of environmental microflorae for diesel oil by comprehensive two-dimensional gas chromatography.

    PubMed

    Penet, Sophie; Vendeuvre, Colombe; Bertoncini, Fabrice; Marchal, Rémy; Monot, Frédéric

    2006-12-01

    In contaminated soils, efficiency of natural attenuation or engineered bioremediation largely depends on biodegradation capacities of the local microflorae. In the present study, the biodegradation capacities of various microflorae towards diesel oil were determined in laboratory conditions. Microflorae were collected from 9 contaminated and 10 uncontaminated soil samples and were compared to urban wastewater activated sludge. The recalcitrance of hydrocarbons in tests was characterised using both gas chromatography (GC) and comprehensive two-dimensional gas chromatography (GCxGC). The microflorae from contaminated soils were found to exhibit higher degradation capacities than those from uncontaminated soil and activated sludge. In cultures inoculated by contaminated-soil microflorae, 80% of diesel oil on an average was consumed over 4-week incubation compared to only 64% in uncontaminated soil and 60% in activated sludge cultures. As shown by GC, n-alkanes of diesel oil were totally utilised by each microflora but differentiated degradation extents were observed for cyclic and branched hydrocarbons. The enhanced degradation capacities of impacted-soil microflorae resulted probably from an adaptation to the hydrocarbon contaminants but a similar adaptation was noted in uncontaminated soils when conifer trees might have released natural hydrocarbons. GCxGC showed that a contaminated-soil microflora removed all aromatics and all branched alkanes containing less than C(15). The most recalcitrant compounds were the branched and cyclic alkanes with 15-23 atoms of carbon. PMID:16477350

  19. Electrically heated, air-cooled thermal modulator and at-column heating for comprehensive two-dimensional gas chromatography.

    PubMed

    Libardoni, Mark; Waite, J Hunter; Sacks, Richard

    2005-05-01

    An instrument for comprehensive two-dimensional gas chromatography (GCxGC) is described using an electrically heated and air-cooled thermal modulator requiring no cryogenic materials or compressed gas for modulator operation. In addition, at-column heating is used to eliminate the need for a convection oven and to greatly reduce the power requirements for column heating. The single-stage modulator is heated by current pulses from a dc power supply and cooled by a conventional two-stage refrigeration unit. The refrigeration unit, together with a heat exchanger and a recirculating pump, cools the modulator to about -30 degrees C. The modulator tube is silica-lined stainless steel with an internal film of dimethylpolysiloxane. The modulator tube is 0.18 mm i.d. x 8 cm in length. The modulator produces an injection plug width as small as 15 ms. PMID:15859594

  20. What Are the Proteolytic Enzymes of Honey and What They Do Tell Us? A Fingerprint Analysis by 2-D Zymography of Unifloral Honeys

    PubMed Central

    Rossano, Rocco; Larocca, Marilena; Polito, Teresa; Perna, Anna Maria; Padula, Maria Carmela; Martelli, Giuseppe; Riccio, Paolo

    2012-01-01

    Honey is a sweet and healthy food produced by honeybees (Apis mellifera L.) from flower nectars. Using bidimensional zymography, we have detected the, until now unrevealed, proteolytic activities present in row honey samples. The resulting zymograms were specific for each type of the four unifloral honey under study, and enzymes were identified as serine proteases by the use of specific inhibitors. Further, using bidimensional electrophoresis, we have shown that honey proteases are able to degrade the major Royal Jelly proteins and in particular MRPJ-1, the protein that promotes queen differentiation in honeybees. Our findings open new perspectives for the better understanding of honeybee development, social behaviour and role in honey production. The now discovered honey proteases may influence honey properties and quality, and bidimensional zymograms might be useful to distinguish between different honey types, establish their age and floral origin, and allow honey certification. PMID:23145107

  1. Two-dimensional DOSY experiment with Excitation Sculpting water suppression for the analysis of natural and biological media

    NASA Astrophysics Data System (ADS)

    Balayssac, Stéphane; Delsuc, Marc-André; Gilard, Véronique; Prigent, Yann; Malet-Martino, Myriam

    2009-01-01

    The Bipolar Pulse Pair Stimulated Echo NMR pulse sequence was modified to blend the original Excitation Sculpting water signal suppression. The sequence is a powerful tool to generate rapidly, with a good spectrum quality, bidimensional DOSY experiments without solvent signal, thus allowing the analysis of complex mixtures such as plant extracts or biofluids. The sequence has also been successfully implemented for a protein at very-low concentration in interaction with a small ligand, namely the salivary IB5 protein binding the polyphenol epigallocatechine gallate. The artifacts created by this sequence can be observed, checked and removed thanks to NPK and NMRnotebook softwares to give a perfect bidimensional DOSY spectrum.

  2. Numerical Algorithms Based on Biorthogonal Wavelets

    NASA Technical Reports Server (NTRS)

    Ponenti, Pj.; Liandrat, J.

    1996-01-01

    Wavelet bases are used to generate spaces of approximation for the resolution of bidimensional elliptic and parabolic problems. Under some specific hypotheses relating the properties of the wavelets to the order of the involved operators, it is shown that an approximate solution can be built. This approximation is then stable and converges towards the exact solution. It is designed such that fast algorithms involving biorthogonal multi resolution analyses can be used to resolve the corresponding numerical problems. Detailed algorithms are provided as well as the results of numerical tests on partial differential equations defined on the bidimensional torus.

  3. Dosimetric Verification and Validation of Conformal and IMRT Treatments Fields with an Ionization Chamber 2D-Array

    NASA Astrophysics Data System (ADS)

    Evangelina, Figueroa M.; Gabriel, Reséndiz G.; Miguel, Pérez P.

    2008-08-01

    A three-dimensional treatment planning system requires comparisons of calculated and measured dose distributions. It is necessary to confirm by means of patient specific QA that the dose distributions are correctly calculated, and that the patient data is correctly transferred to and delivered by the treatment machine. We used an analysis software for bi-dimensional dosimetric verification of conformal treatment and IMRT fields using as objective criterion the gamma index. An ionization chamber bi-dimensional array was used for absolute dose measurement in the complete field area.

  4. The Assessment of Present-Moment Awareness and Acceptance: The Philadelphia Mindfulness Scale

    ERIC Educational Resources Information Center

    Cardaciotto, LeeAnn; Herbert, James D.; Forman, Evan M.; Moitra, Ethan; Farrow, Victoria

    2008-01-01

    The purpose of this project was to develop a bidimensional measure of mindfulness to assess its two key components: present-moment awareness and acceptance. The development and psychometric validation of the Philadelphia Mindfulness Scale is described, and data are reported from expert raters, two nonclinical samples (n = 204 and 559), and three…

  5. Acculturation and Adjustment among Immigrant Chinese Parents: Mediating Role of Parenting Efficacy

    ERIC Educational Resources Information Center

    Costigan, Catherine L.; Koryzma, Celine M.

    2011-01-01

    This study examined parenting efficacy beliefs as a mediator of the association between acculturation and adjustment. The sample consisted of 177 immigrant Chinese mothers and fathers with early adolescent children in Canada. Acculturation was assessed bidimensionally as Canadian and Chinese orientations. A latent psychological adjustment variable…

  6. Cycloartane triterpenoids from Guarea macrophylla.

    PubMed

    Lago, João Henrique G; Roque, Nídia F

    2002-06-01

    Nine cycloartane triterpenoids, including two new derivatives 22,25-dihydroxy-cycloart-23E-en-3-one and 24-methylenecycloartane-3 beta,22-diol have been isolated from leaves of Guarea macrophylla. The structures were elucidated by interpretation of spectral data, mainly 1H and 13C NMR, including bidimensional analysis (HOMOCOSY, HMQC and HMBC). PMID:12031420

  7. Acculturation and Eating Disorders in a Mexican American Community Sample

    ERIC Educational Resources Information Center

    Cachelin, Fary M.; Phinney, Jean S.; Schug, Robert A.; Striegel-Moore, Ruth H.

    2006-01-01

    Our purpose was to investigate acculturation and eating disorders by examining the role of ethnic identity and by utilizing a bidimensional perspective toward two cultures. We predicted that orientation toward European American culture and lower ethnic identity would be positively associated with eating disorders. Participants were 188 Mexican…

  8. Exploratory Procedures of Tactile Images in Visually Impaired and Blindfolded Sighted Children: How They Relate to Their Consequent Performance in Drawing

    ERIC Educational Resources Information Center

    Vinter, Annie; Fernandes, Viviane; Orlandi, Oriana; Morgan, Pascal

    2012-01-01

    The aim of the present study was to compare the types of exploratory procedures employed by children when exploring bidimensional tactile patterns and correlate the use of these procedures with the children's shape drawing performance. 18 early blind children, 20 children with low vision and 24 age-matched blindfolded sighted children aged…

  9. Complete characterization of a spatiotemporal pulse shaper with two-dimensional Fourier transform spectral interferometry

    NASA Astrophysics Data System (ADS)

    Amir, W.; Planchon, T. A.; Durfee, C. G.; Squier, J. A.

    2007-04-01

    Spatiotemporal pulse shaping is characterized with two-dimensional Fourier transform spectral interferometry. A deformable-mirror-based bidimensional pulse shaper is used to create simple spatiotemporal structures on a femtosecond pulse, structures that are directly calculated from the measured spatiospectral phases and intensities.

  10. From Newton's Second Law to Huygens's Principle: Visualizing Waves in a Large Array of Masses Joined by Springs

    ERIC Educational Resources Information Center

    Dolinko, A. E.

    2009-01-01

    By simulating the dynamics of a bidimensional array of springs and masses, the propagation of conveniently generated waves is visualized. The simulation is exclusively based on Newton's second law and was made to provide insight into the physics of wave propagation. By controlling parameters such as the magnitude of the mass and the elastic…

  11. Modular detector for deep underwater registration of muons and muon groups

    NASA Technical Reports Server (NTRS)

    Demianov, A. I.; Sarycheva, L. I.; Sinyov, N. B.; Varadanyan, I. N.; Yershov, A. A.

    1985-01-01

    Registration and identification of muons and muon groups penetrating into the ocean depth, can be performed using a modular multilayer detector with high resolution bidimensional readout - deep underwater calorimeter (project NADIR). Laboratory testing of a prototype sensor cell with liquid scintillator in light-tight casing, testifies to the practicability of the full-scale experiment within reasonable expences.

  12. A molecular chemical approach to the magnetic multilayers

    NASA Astrophysics Data System (ADS)

    Coronado, E.; Galán-Mascarós, J. R.; Gómez-García, C. J.; Burriel, R.

    1999-05-01

    Using the bi-dimensional bimetallic networks based upon oxalate complexes, it is possible to prepare new multilayered materials by insertion of 'electroactive' molecules in between these layers. According to this approach a new family of compounds presenting alternating ferromagnetic—paramagnetic layers have been successfully prepared. Here we present the magnetic and specific heat characterization.

  13. Tridimensional Acculturation and Adaptation among Jamaican Adolescent-Mother Dyads in the United States

    ERIC Educational Resources Information Center

    Ferguson, Gail M.; Bornstein, Marc H.; Pottinger, Audrey M.

    2012-01-01

    A bidimensional acculturation framework cannot account for multiple destination cultures within contemporary settlement societies. A "tridimensional model" is proposed and tested among Jamaican adolescent-mother dyads in the United States compared to Jamaican Islander, European American, African American, and other Black and non-Black U.S.…

  14. Dirac operator on a disk with global boundary conditions

    SciTech Connect

    Falomir, H.; Gamboa Saravi, R.E.; Santangelo, E.M.

    1998-01-01

    We compute the functional determinant for a Dirac operator in the presence of an Abelian gauge field on a bidimensional disk, under global boundary conditions of the type introduced by Atiyah{endash}Patodi{endash}Singer. We also discuss the connection between our result and the index theorem. {copyright} {ital 1998 American Institute of Physics.}

  15. Multidimensional Properties of LOT-R: Effects of Optimism and Pessimism on Career and Well-Being Related Variables in Adolescents.

    ERIC Educational Resources Information Center

    Creed, Peter A.; Patton, Wendy; Bartrum, Dee

    2002-01-01

    Exploratory and confirmatory factor analyses of data from the Life Orientation Test Revised for 504 adolescents demonstrated its bidimensionality. High optimism was associated with high levels of career planning, exploration, decision-making confidence, and career-related goals. High pessimism was associated with career indecision, low…

  16. Promoting Hope: Suggestions for School Counselors

    ERIC Educational Resources Information Center

    Pedrotti, Jennifer Teramoto; Edwards, Lisa M.; Lopez, Shane J.

    2008-01-01

    School counselors need multiple resources to assist today's students in developing to their fullest potential. This development might often be measured outwardly by academic success; however, psychological and emotional well-being of students is a large part of this success. The construct of hope is defined as a bidimensional characteristic…

  17. Dimensions of Acculturation: Associations with Health Risk Behaviors among College Students from Immigrant Families

    ERIC Educational Resources Information Center

    Schwartz, Seth J.; Weisskirch, Robert S.; Zamboanga, Byron L.; Castillo, Linda G.; Ham, Lindsay S.; Huynh, Que-Lam; Park, Irene J. K.; Donovan, Roxanne; Kim, Su Yeong; Vernon, Michael; Davis, Matthew J.; Cano, Miguel A.

    2011-01-01

    In the present study, we examined a bidimensional model of acculturation (which includes both heritage and U.S. practices, values, and identifications) in relation to hazardous alcohol use, illicit drug use, unsafe sexual behavior, and impaired driving. A sample of 3,251 first- and second-generation immigrant students from 30 U.S. colleges and…

  18. Separating Optimism and Pessimism: A Robust Psychometric Analysis of the Revised Life Orientation Test (LOT-R)

    ERIC Educational Resources Information Center

    Herzberg, Philipp Yorck; Glaesmer, Heide; Hoyer, Jurgen

    2006-01-01

    The internal structure of the revised Life Orientation Test (LOT-R, German version; M. F. Scheier, C. S. Carver, & M. W. Bridges, 1994) was analyzed in a sample of 46,133 participants who ranged in age from 18 years to 103 years. Confirmatory factor analysis showed that dispositional optimism, as measured by the LOT-R, is bidimensional, …

  19. Petroleum Weathering Associated with Hydrocarbon Migration and Seepage, a Case Study From the Santa Barbara Channel, CA.

    NASA Astrophysics Data System (ADS)

    Wardlaw, G. D.; Nelson, R. K.; Reddy, C. M.; Valentine, D. L.

    2005-12-01

    A 2003 report by the National Research Council estimates that 50 to 70 percent of oil that is released into the sea is from natural seeps (National Research Council, 2003), indicating that catastrophic oil spills or the runoff from roads and highways are not the major sources of oil in the marine environment. For example, approximately 37 tons of petroleum is emitted daily from seeps off the coast of Santa Barbara, California (Quigley et al. 1996). The Santa Barbara seeps are some of the most active in the world and have been releasing petroleum for thousands of years. Sheens of oil on the water surface and tar patches on the beaches are ubiquitous along the coastline of Santa Barbara and are continuing reminders of this natural process. Although the geochemistry of these seeps have been studied in the past, it has been hindered by the complexity of the petroleum hydrocarbons and the inability of traditional gas chromatography to separate, identify, and quantify each component of the oil. To expand on these previous efforts, we have begun to use comprehensive two-dimensional gas chromatography (GCxGC). This new technology provides at least an order of magnitude increase in the resolution and detection of petroleum hydrocarbons compared to traditional methods. Preliminary work using GCxGC has focused on examining the chemical composition of unrefined petroleum as it migrates up from depth through natural faults to the seafloor, from the seafloor to the sea surface, and from the sea surface to local beaches. Petroleum collected from a subsurface reservoir (Platform Holly Well 2342-15) is composed of a wide range of resolved petroleum hydrocarbons including n-alkanes, branched alkanes, cycloalkanes, linear alkane benzenes, polycyclic aromatic hydrocarbons, steranes, hopanes, cyclic isoprenoids, and very large branched biomarkers with 38 to 40 carbons. This product is significantly different than oil emerging from the seafloor at the Jackpot seep, which we believe is

  20. Assessment of opacimeter calibration on kraft pulp mills

    NASA Astrophysics Data System (ADS)

    Gomes, Joa˜o. F. P.

    This paper describes the methodology and specific techniques for calibrating automatic on-line industrial emission analysers, specifically equipments that measure total suspended dust installed in pulp mills within the scope of Portuguese Regulation No. 286/93 on air quality. The calibration of opacimeters is a multi-parameter relationship instead of the bidimensional calibration which is used in industrial practice. For a stationary source from a pulp mill such as the recovery boiler stack, which is subjected to significant variations, the effects of parameters such as the humidity and gas temperature, deviations of isokinetism, size range of particles and characteristic transmittance of equipment are analysed. The multivariable analysis of a considerable set of data leads to an estimate of about 98% of equipment transmittance over the other parameters with a level of significance greater than 0.99 which is a validation of the bidimensional practical calibrations.

  1. Use of digital wave front reconstruction for vibration analysis

    NASA Astrophysics Data System (ADS)

    Picart, Pascal; Leval, Julien; Boileau, Jean-Pierre; Pascal, Jean-Claude; Dalmont, Jean-Pierre

    2006-09-01

    This paper aims to present the different opportunities using digital wave front reconstruction in vibration analysis. The paper deals with off axis digital holography for which the wave front reconstruction is performed by fast Fourier transform methods. According to this way for the object plane reconstruction, we discuss about image formation by considering the exposure time of the detector. For the case of a long exposure time compared to the vibration period, that is the time-averaging regime, applications are presented, examples of which include vibrations of a clarinet reed and detection of defaults in a dome mode. For the case of a short exposure time compared to the vibration period, algorithm for the full field bidimensional amplitude and phase retrieving is presented. Applications of the method are presented, example of which include modal characterization of loudspeakers and bidimensional vibrometry of elastomer components.

  2. [Development of the Japanese Optimism and Pessimism Scale: reliability and validity].

    PubMed

    Toyama, Miki

    2013-08-01

    This study reports about the construction of a bidimensional measure of optimism and pessimism (defined as positive and negative outcome expectancies), called the Japanese Optimism and Pessimism Scale (J-OPS), and examines its reliability and validity. The participants were college students. The results revealed the following: (a) the J-OPS had sufficient reliability and validity, (b) optimism and pessimism were bidimensional in structure, (c) the general pattern of correlations with external criteria of psychological well-being (positive and negative affectivity). After controlling for optimism and pessimism respectively, it indicated that these two constructs were partially independent of each other. Namely, optimism, but not pessimism, was found to be a consistent predictor of positive affectivity (psychological well-being), whereas pessimism, but not optimism, was found to be a predictor of negative affectivity (psychological distress). PMID:24063152

  3. Construction and validation of the Measurement of Acculturation Strategies for People of African Descent (MASPAD).

    PubMed

    Obasi, Ezemenari M; Leong, Frederick T L

    2010-10-01

    This paper describes the development of the Measurement of Acculturation Strategies for People of African Descent (MASPAD), a bidimensional instrument designed to assess acculturation strategies (i.e., Traditionalist, Integrationist, Assimilationist, and Marginalist). Two studies were conducted to describe the development of the MASPAD and to assess its psychometric properties. Data were collected from 367 African American participants in Atlanta, GA; Columbus, OH; Los Angeles; and New York City, NY. The MASPAD consistently produced scores with adequate reliability and independent raters provided initial evidence for face and content validity. Pearson correlation coefficients supported the purported orthogonality of the MASPAD subscales. The MASPAD was found to be a significant predictor of cultural worldview and values. The bidimensional model of acculturation theorized to exist in the MASPAD was supported with a confirmatory factor analysis on data collected from 831 participants. Future directions for this body of research are discussed. PMID:21058816

  4. Avoiding sensor blindness in Geiger mode avalanche photodiode arrays fabricated in a conventional CMOS process

    NASA Astrophysics Data System (ADS)

    Vilella, E.; Diéguez, A.

    2011-12-01

    The need to move forward in the knowledge of the subatomic world has stimulated the development of new particle colliders. However, the objectives of the next generation of colliders sets unprecedented challenges to the detector performance. The purpose of this contribution is to present a bidimensional array based on avalanche photodiodes operated in the Geiger mode to track high energy particles in future linear colliders. The bidimensional array can function in a gated mode to reduce the probability to detect noise counts interfering with real events. Low reverse overvoltages are used to lessen the dark count rate. Experimental results demonstrate that the prototype fabricated with a standard HV-CMOS process presents an increased efficiency and avoids sensor blindness by applying the proposed techniques.

  5. Qualitative drug analysis of hair extracts by comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry.

    PubMed

    Guthery, Bill; Bassindale, Tom; Bassindale, Alan; Pillinger, Colin T; Morgan, Geraint H

    2010-06-25

    A technique using comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GCxGC/TOFMS) is applied to a qualitative analysis of three sample extracts from hair suspected of containing various drug compounds. The samples were also subjected to a quantitative target analysis for codeine, morphine, 6-monoacetylmorphine (6-MAM), amphetamine, methamphetamine, methylenedioxyamphetamine (MDA), methylenedioxymethylamphetamine (MDMA), methadone, and benzylpiperazine (BZP) by liquid chromatography-tandem mass spectrometry (LC-MS/MS). GCxGC/TOFMS provided a non-specific procedure that identified various drugs, metabolites, and impurities not included in the target analysis. They included cocaine, diazepam, and methaqualone (quaalude). Comprehensive GCxGC separation was achieved using twin-stage cryo-modulation to focus eluant from a DB-5 ms (5% phenyl) to a BPX50 (50% phenyl) GC column. The TOF mass spectrometer provided unit mass resolution in the mass range m/z 5-1000 and rapid spectral acquisition (< or = 500spectra/s). Clean mass spectra of the individual components were obtained using mass spectral deconvolution software. The 'unknown' components were identified by comparison with mass spectra stored in a library database. PMID:20471020

  6. Catalytic Hydrotreatment of Humins in Mixtures of Formic Acid/2-Propanol with Supported Ruthenium Catalysts.

    PubMed

    Wang, Yuehu; Agarwal, Shilpa; Kloekhorst, Arjan; Heeres, Hero Jan

    2016-05-10

    The catalytic hydrotreatment of humins, which are the solid byproducts from the conversion of C6 sugars (glucose, fructose) into 5-hydroxymethylfurfural (HMF) and levulinic acid (LA), by using supported ruthenium catalysts has been investigated. Reactions were carried out in a batch setup at elevated temperatures (400 °C) by using a hydrogen donor (formic acid (FA) in isopropanol (IPA) or hydrogen gas), with humins obtained from d-glucose. Humin conversions of up to 69 % were achieved with Ru/C and FA, whereas the performance for Ru on alumina was slightly poorer (59 % humin conversion). Humin oils were characterized by using a range of analytical techniques (GC, GC-MS, GCxGC, gel permeation chromatography) and were shown to consist of monomers, mainly alkyl phenolics (>45 % based on compounds detectable by GC) and higher oligomers. A reaction network for the reaction is proposed based on structural proposals for humins and the main reaction products. PMID:26836970

  7. Aromatic chemicals by iron-catalyzed hydrotreatment of lignin pyrolysis vapor.

    PubMed

    Olcese, Roberto Nicolas; Lardier, George; Bettahar, Mohammed; Ghanbaja, Jaafar; Fontana, Sébastien; Carré, Vincent; Aubriet, Frédéric; Petitjean, Dominique; Dufour, Anthony

    2013-08-01

    Lignin is a potential renewable material for the production of bio-sourced aromatic chemicals. We present the first hydrotreatment of lignin pyrolysis vapors, before any condensation, using inexpensive and sustainable iron-silica (Fe/SiO2 ) and iron-activated carbon (Fe/AC) catalysts. Lignin pyrolysis was conducted in a tubular reactor and vapors were injected in a fixed bed of catalysts (673 K, 1 bar) with stacks to investigate the profile of coke deposit. More than 170 GC-analyzable compounds were identified by GCxGC (heart cutting)/flame ionization detector mass spectrometry. Lignin oligomers were analyzed by very high resolution mass spectrometry, called the "petroleomic" method. They are trapped by the catalytic fixed bed and, in particular, by the AC. The catalysts showed a good selectivity for the hydrodeoxygenation of real lignin vapors to benzene, toluene, xylenes, phenol, cresols, and alkyl phenols. The spent catalysts were characterized by temperature-programmed oxidation, transmission electron microscopy (TEM), and N2 sorption. Micropores in the Fe/AC catalyst are completely plugged by coke deposits, whereas the mesoporous structure of Fe/SiO2 is unaffected. TEM images reveal two different types of coke deposit: 1) catalytic coke deposited in the vicinity of iron particles and 2) thermal coke (carbonaceous particles ≈1 μm in diameter) formed from the gas-phase growth of lignin oligomers. PMID:23784799

  8. Molecular Characterization of Organic Indicators of Petroleum Biosouring

    NASA Astrophysics Data System (ADS)

    Nowak, J.; Weber, R.; Loutey, D.; Coates, J. D.; Goldstein, A. H.

    2015-12-01

    The production of sulfide in a petroleum reservoir by anaerobic sulfate reducing microorganisms (SRM) is environmentally, industrially, and epidemiologically hazardous. More knowledge is needed about the anaerobic respiration pathway of SRM in petroleum, and whether the activity of SRM could be effectively inhibited using nitrate or perchlorate treatments. In order to understand the molecular transformations and metabolic fingerprints of SRM in petroleum reservoirs, and how they are altered by nitrate or perchlorate treatments, the Coates and Goldstein Laboratories at UC-Berkeley have run controlled column incubation studies of petroleum from an oil reservoir. By using two dimensional gas chromatography (GCxGC) with high resolution time-of-flight mass spectrometry coupled to vacuum ultraviolet radiation at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory (LBNL), detailed chemical characterizations of hydrocarbons from approximately C9-C30 have been completed, separating the complete oil sample by number of carbon atoms and chemical classes (including normal alkanes, branched alkanes, number of alkyl rings, and number of aromatic rings) corresponding to petroleum transformations in sulfate, nitrate, and perchlorate reducing environments. Results demonstrate that the anaerobic pathway of SRM preferentially involves the transformation of heavier polycyclic aromatic hydrocarbons (PAHs), and that a large number of products are created that contain either two or four oxygen atoms, suggesting fumarate additions initialize the anaerobic process.

  9. The discriminant pixel approach: a new tool for the rational interpretation of GCxGC-MS chromatograms.

    PubMed

    Vial, Jérôme; Pezous, Benoît; Thiébaut, Didier; Sassiat, Patrick; Teillet, Béatrice; Cahours, Xavier; Rivals, Isabelle

    2011-01-30

    GCxGC is now recognized as the most suited analytical technique for the characterization of complex mixtures of volatile compounds; it is implemented worldwide in academic and industrial laboratories. However, in the frame of comprehensive analysis of non-target analytes, going beyond the visual examination of the color plots remains challenging for most users. We propose a strategy that aims at classifying chromatograms according to the chemical composition of the samples while determining the origin of the discrimination between different classes of samples: the discriminant pixel approach. After data pre-processing and time-alignment, the discriminatory power of each chromatogram pixel for a given class was defined as its correlation with the membership to this class. Using a peak finding algorithm, the most discriminant pixels were then linked to chromatographic peaks. Finally, crosschecking with mass spectrometry data enabled to establish relationships with compounds that could consequently be considered as candidate class markers. This strategy was applied to a large experimental data set of 145 GCxGC-MS chromatograms of tobacco extracts corresponding to three distinct classes of tobacco. PMID:21215866

  10. Automatic classification of clouds on Meteosat imagery - Application to high-level clouds

    NASA Technical Reports Server (NTRS)

    Desbois, M.; Seze, G.; Szejwach, G.

    1982-01-01

    A statistical classification method based on clustering on three-dimensional histograms is applied to the three channels of the Meteosat imagery. The results of this classification are studied for different cloud cover cases over tropical regions. For high-level cloud classes, it is shown that the bidimensional IR-water vapor histogram allows one to deduce the cloud top temperature even for semi-transparent clouds.

  11. Traumatic tricuspid insufficiency in a kitten.

    PubMed

    Closa, J M; Font, A

    1999-01-01

    A four-month-old, male, common European kitten developed pleural effusion and ascites after falling from a fourth-floor flat. Radiographic, bidimensional echocardiography and color-flow Doppler findings were compatible with right-sided atrioventricular valve insufficiency. Necropsy confirmed the diagnosis that tricuspid insufficiency resulted from the rupture of the chordae tendineae of the nonseptal cusp of the valve at the level of the cranial papillary muscle insertion in the right ventricle. PMID:9934923

  12. Towards the identification of cassava root protein genes.

    PubMed

    De Souza, C R B; Carvalho, L J C B; De Almeida, E R P; Gander, E S

    2002-01-01

    The protein population of cassava root layers was characterized by SDS-PAGE and bidimensional polyacrylamide gel electrophoresis. SDS-Page revealed the presence of a protein population in the molecular weight range between 94 and 20 kDa. The expression pattern of these proteins was well-defined within the different layers. Partial protein sequence analyses and preliminary results on the layer-specific expression pattern obtained with Northern analyses are presented. PMID:12602941

  13. Geometry of Prismatic Tensegrity Constructions Composed of Three and Four-strut Cells

    NASA Astrophysics Data System (ADS)

    Olejníková, Tatiana

    2014-11-01

    In the paper there is described geometry of double layer tensegrity constructions composed of prismatic cells with rhombic configuration of three or four strut bases so-called prismatic Tensegrity constructions. There are described bi-dimensional assemblies creating double layer grids of three or four-strut cells with a node-on-node junction. The grids can be planar, of one or two curvature constructions.

  14. Cloud modeling of a quiet solar region in Halpha .

    NASA Astrophysics Data System (ADS)

    Bostanci, Z. F.; Al Erdoğan, N.

    We present chromospheric cloud modeling on the basis of Halpha profile-sampling images taken with the Interferometric Bidimensional Spectrometer (IBIS) at the Dunn Solar Telescope (DST). We choose the required reference background profile by using theoretical NLTE profile synthesis. The resulting cloud parameters are converted into estimates of physical parameters (temperature and various densities). Their mean values compare well with the VAL-C model.

  15. Mechanichal Behavior of a Noncohesive Packing at Small Deformations: Deviation From Continuum Elasticity

    NASA Astrophysics Data System (ADS)

    Amar, El Hadji Bouya; Clamond, Didier; Fraysse, Nathalie; Rajchenbach, Jean

    2009-06-01

    In order to specify the mechanical behavior of grain piles, we investigate the response of a non-cohesive bidimensional packing of cylinders submitted to a point load. By means of image processing, we have an accurate access to the individual grain displacements in the reversible regime. The measured displacement field deviates unambiguously from the predictions of Continuum Elasticity. The data reveal a partial agreement with the diffusive models of Harr (1966) or of Coppersmith et al. (1996).

  16. Ag{sub 2}CuMnO{sub 4}: A new silver copper oxide with delafossite structure

    SciTech Connect

    Munoz-Rojas, David; Subias, Gloria; Fraxedas, Jordi; Martinez, Benjamin; Casas-Cabanas, Montse; Canales-Vazquez, Jesus; Gonzalez-Calbet, Jose; Garcia-Gonzalez, Ester; Walton, Richard I.; Casan-Pastor, Nieves . E-mail: nieves@icmab.es

    2006-12-15

    The use of hydrothermal methods has allowed the synthesis of a new silver copper mixed oxide, Ag{sub 2}CuMnO{sub 4}, the first example of a quaternary oxide containing both elements. It crystallizes with the delafossite 3R structure, thus being the first delafossite to contain both Ag and Cu. Synthesis conditions affect the final particle size (30-500nm). Powder X-ray diffraction Rietveld refinement indicates a trigonal structure (R3-bar m) and cell parameters a=2.99991A and c=18.428A, where Cu and Mn are disordered within the octahedral B positions in the plane and linearly coordinated Ag occupies de A position between layers. X-ray absorption near edge spectroscopy (XANES) for copper and manganese, and XPS for silver evidence +2, +4, and +1 oxidation states. The microstructure consists of layered parts that may form large twins showing 5nm nanodomains. Finally, magnetic measurements reveal the existence of ferromagnetic coupling yielding in-plane moments that align antiferromagnetically at lower temperatures. The singularity of the new phase resides on the fact that is an example of a bidimensional arrangement of silver and copper in an oxide that also shows clear bidimensionality in its physical properties. That is of special relevance to the field of high T{sub c} superconducting oxides, while the ferromagnetic coupling in a bidimensional system deserves itself special attention.

  17. Protein microdeposition using a conventional ink-jet printer.

    PubMed

    Roda, A; Guardigli, M; Russo, C; Pasini, P; Baraldini, M

    2000-03-01

    Many recent bioanalytical systems based on immunologic and hybridization reactions in a mono- or bidimensional microarray format require technology that can produce arrays of spots containing biospecific molecules. Some microarray deposition instruments are commercially available, and other devices have been described in recent papers. We describe a system obtained by adapting a commercial ink-jet printer and used to produce mono- and bidimensional arrays of spots containing horseradish peroxidase on cellulose paper. In a few minutes, it was possible to obtain bidimensional arrays containing several thousands of spots with a diameter as low as 0.2 mm, with each of which requiring only a few nanoliters of the enzyme deposition solution. The quantity of enzyme in each spot was evaluated with a chemiluminescent reaction and a charge-coupled device-based, low-light imaging luminograph. The chemiluminescence measurements revealed that the reproducibility of the enzyme deposition was satisfactory for analytical purposes, with the variation coefficients being lower than 10% in almost all cases. PMID:10723562

  18. Ag 2CuMnO 4: A new silver copper oxide with delafossite structure

    NASA Astrophysics Data System (ADS)

    Muñoz-Rojas, David; Subías, Gloria; Oró-Solé, Judith; Fraxedas, Jordi; Martínez, Benjamín; Casas-Cabanas, Montse; Canales-Vázquez, Jesús; Gonzalez-Calbet, Jose; García-González, Ester; Walton, Richard I.; Casañ-Pastor, Nieves

    2006-12-01

    The use of hydrothermal methods has allowed the synthesis of a new silver copper mixed oxide, Ag 2CuMnO 4, the first example of a quaternary oxide containing both elements. It crystallizes with the delafossite 3 R structure, thus being the first delafossite to contain both Ag and Cu. Synthesis conditions affect the final particle size (30-500 nm). Powder X-ray diffraction Rietveld refinement indicates a trigonal structure (R3¯m) and cell parameters a=2.99991 Å and c=18.428 Å, where Cu and Mn are disordered within the octahedral B positions in the plane and linearly coordinated Ag occupies de A position between layers. X-ray absorption near edge spectroscopy (XANES) for copper and manganese, and XPS for silver evidence +2, +4, and +1 oxidation states. The microstructure consists of layered particles that may form large twins showing 5 nm nanodomains. Finally, magnetic measurements reveal the existence of ferromagnetic coupling yielding in-plane moments that align antiferromagnetically at lower temperatures. The singularity of the new phase resides on the fact that is an example of a bidimensional arrangement of silver and copper in an oxide that also shows clear bidimensionality in its physical properties. That is of special relevance to the field of high Tc superconducting oxides, while the ferromagnetic coupling in a bidimensional system deserves itself special attention.

  19. Toward the Complete Characterization of Atmospheric Organic Particulate Matter: Derivatization and Two-Dimensional Comprehensive Gas Chromatography/Time of Flight Mass Spectrometry as a Method for the Determination of Carboxylic Acids

    NASA Astrophysics Data System (ADS)

    Boris, Alexandra Jeanne

    Understanding the composition of atmospheric organic particulate matter (OPM) is essential for predicting its effects on climate, air quality, and health. However, the polar oxygenated fraction (PO-OPM), which includes a significant mass contribution from carboxylic acids, is difficult to speciate and quantitatively determine by current analytical methods such as gas chromatography-mass spectrometry (GC-MS). The method of chemical derivatization and two-dimensional GC with time of flight MS (GCxGC/TOF-MS) was examined in this study for its efficacy in: 1) quantifying a high percentage of the total organic carbon (TOC) mass of a sample containing PO-OPM; 2) quantitatively determining PO-OPM components including carboxylic acids at atmospherically relevant concentrations; and 3) tentatively identifying PO-OPM components. Two derivatization reagent systems were used in this study: BF3/butanol for the butylation of carboxylic acids, aldehydes, and acidic ketones, and BSTFA for the trimethylsilylation (TMS) of carboxylic acids and alcohols. Three alpha-pinene ozonolysis OPM filter samples and a set of background filter samples were collected by collaborators in a University of California, Riverside environmental chamber. Derivatization/GCxGC TOF-MS was used to tentatively identify some previously unidentified α-pinene ozonolysis products, and also to show the characteristics of all oxidation products determined. Derivatization efficiencies as measured were 40-70% for most butyl derivatives, and 50-58% for most trimethylsilyl derivatives. A thermal optical method was used to measure the TOC on each filter, and a value of the quantifiable TOC mass using a gas chromatograph was calculated for each sample using GCxGC separation and the mass-sensitive response of a flame ionization detector (FID). The TOC quantified using TMS and GCxGC-FID (TMS/TOCGCxGC FID) accounted for 15-23% of the TOC measured by the thermal-optical method. Using TMS and GCxGC/TOF-MS, 8.85% of the

  20. Identification and quantification of individual chemical compounds in biogenic secondary organic aerosols using GCxGC-VUV/EI-HRTOFMS

    NASA Astrophysics Data System (ADS)

    Decker, M.; Worton, D. R.; Isaacman, G. A.; Chan, A. W.; Ruehl, C.; Zhao, Y.; Wilson, K. R.; Goldstein, A. H.

    2012-12-01

    Atmospheric aerosols have adverse effects on human health and air quality and affect radiative forcing and thus climate. While the organic fraction of aerosols is substantial, the sources and chemistry leading to the formation of secondary organic aerosols are very poorly understood. Characterizing individual compounds present in organic aerosol provides insights into the sources, formation mechanisms and oxidative transformations that have taken place. Fifteen aerosol samples collected over a 5 day period at the Blodgett Forest Research Station in the Sierra Nevada Mountains, part of the Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX) in July 2009, were analyzed using comprehensive two dimensional gas chromatography with high resolution time of flight mass spectrometry (GCxGC-HRTOFMS). Approximately 600 compounds were observed in each sample as significant peaks in the chromatogram. Of these, around a third were identified by matching the unique electron ionization (EI) mass spectrum of each compound to the NIST library of characteristic fragmentation patterns. One filter sample was also analyzed using vacuum ultraviolet ionization (VUV) instead of EI. This 'soft' ionization technique results in much less fragmentation yielding the molecular ion of each compound, from which the exact mass was determined. If the formula of the EI library matched compound equaled the high mass resolution VUV molecular weight within a certain tolerance (< 30 ppm), then the library match was considered confirmed; 226 compounds were identified in this way. Using the VUV technique 234 additional compounds that were not in the EI mass spectral database were assigned chemical formulas based on the observed molecular weights. The chemical formulas in conjunction with the location of the compound in the GCxGC chromatogram were used to provide further classification of these compounds based on their likely functionalization. The broad array of observed oxygenated

  1. Heterogeneous OH oxidation of motor oil particles causes selective depletion of branched and less cyclic hydrocarbons

    NASA Astrophysics Data System (ADS)

    Isaacman, G.; Chan, A. W.; Nah, T.; Worton, D. R.; Ruehl, C.; Kolesar, K. R.; Cappa, C. D.; Wilson, K. R.; Goldstein, A. H.

    2012-12-01

    Motor oil serves as a useful model system for atmospheric oxidation of hydrocarbon mixtures typical of anthropogenic atmospheric particulate matter, but its complexity often prevents comprehensive chemical speciation. In this work we fully characterize this formerly "unresolved complex mixture" at the molecular level using two-dimensional gas chromatography with vacuum-ultraviolet ionization and high resolution time-of-flight mass spectrometry (GCxGC/VUV-HRTOFMS). This "soft" ionization technique allows us to classify compounds by carbon number, cyclization, and branching, resolving 80-90% of hydrocarbon mass in petroleum fuels. Nucleated motor oil (15W-40) particles were oxidized by OH radicals in a flow tube reactor and the oxidative decay and transformations of straight, branched, cyclic, and polycyclic alkanes were measured using high resolution analysis. Oxidation of hydrocarbons in a complex aerosol is found to be efficient and steady, with approximately three-quarters (0.72 ± 0.06) of OH collisions yielding a reaction. Reaction rates of individual hydrocarbons are structurally dependent: compared to normal alkanes, reaction rates increased by 20-50% with branching, while rates decreased ~20% per non-aromatic ring present. These differences in rates will alter particle composition as a function of oxidation, with depletion of branched and enrichment of cyclic hydrocarbons. Compositional changes in turn influence oxidation pathways, since functionalization reactions are more prevalent with cyclic compounds. The GCxGC plane provides separation by parameters typically used in current models (volatility and polarity) so is used to explore changes in oxidation mechanisms of motor oil. Estimates of fragmentation and functionalization of this complex hydrocarbon mixture are compared to simple model compounds based on movement in the chromatographic plane.

  2. Advances in the gas chromatographic determination of persistent organic pollutants in the aquatic environment.

    PubMed

    van Leeuwen, S P J; de Boer, J

    2008-04-01

    Environmental chemists have been challenged for over 30 years to analyse complex mixtures of halogenated organic pollutants like polychlorinated biphenyls (PCBs), polychlorinated alkanes (PCAs), polybrominated diphenyl ethers (PBDEs) and polychlorinated dibenzo-p-dioxins and polychlorinated furans (PCDD/Fs). Gas chromatography (GC) often proved to be the method of choice because of its high resolution. The recent developments in the field of comprehensive two-dimensional GC (GCxGC) show that this technique can provide much more information than conventional (single-column) GC. Large volume injection (e.g. by programmed temperature vaporiser, or on-column injection) can be employed for the injection of tens of microliters of sample extract, in that way substantially improving the detection limits. Electron-capture detection (ECD) is a sensitive detection method but unambiguous identification is not possible and misidentification easily occurs. Mass spectrometric (MS) detection substantially improves the identification and the better the resolution (as with MS/MS, time-of-flight (TOF) MS and high-resolution (HR)MS), the lower the chances of misidentification are. Unfortunately, this comes only with substantially higher investments and maintenance costs. Co-extracted lipids, sulphur and other interferences can disturb the GC separation and detection leading to unreliable results. Extraction, and more so, sample clean-up and fractionation, are crucial steps prior to the GC analysis of these pollutants. Recent developments in sample extraction and clean-up show that selective pressurised liquid extraction (PLE) is an effective and efficient extraction and clean-up technique that enables processing of multiple samples in less than 1h. Quality assurance tools such as interlaboratory studies and reference materials are very well established for PCDD/Fs and PCBs but the improvement of that infrastructure is needed for brominated flame retardants, PCAs and toxaphene. PMID

  3. Investigation of the detailed chemical composition of organic aerosol in a South East Asian Rainforest

    NASA Astrophysics Data System (ADS)

    Hamilton, Jacqueline; Ward, Martyn; Rami Alfarra, M.; Lewis, Alastair; McFiggans, Gordon; Robinson, Niall

    2010-05-01

    The formation of secondary organic aerosol (SOA) in tropical regions is a key uncertainty in quantifying the effect of man made emissions on the climate. Large quantities of volatile organic compounds are emitted from natural biogenic sources in the tropics, including isoprene, monoterpenes and sequiterpenes. There are very few studies of the detailed chemical composition of organic aerosols in tropical rainforest regions, but these would provide information on the importance of primary versus secondary organic aerosols, the key VOC precursors, oxidation state and volatility. Particle samples were collected in a tropical rainforest at Danum Valley in Borneo as part of the OP3 field campaign in 2008. Twenty four hour filter samples were collected at the Global Atmospheric Watch station at a height of around 10 m and shipped back to the laboratory (below -4 °C) for offline analysis. The OA composition was studied using multiple high resolution chromatographic techniques including comprehensive two dimensional gas chromatography coupled to time of flight mass spectrometry (GCXGC-TOFMS) and liquid chromatography coupled to ion trap mass spectrometry (LC-MSn). The composition was directly compared to chamber generated SOA (as part of the Aerosol Coupling in the Earths System , ACES, experiment) to determine SOA tracers. A biogenic SOA tracer MS fragmentation library was constructed and a number of SOA components from limonene, linalool and -pinene were identified in the rainforest OA. Very high resolution mass spectrometry (Fourier Transform Ion Cyclotron Resonance FTICR-MS) allowed the O:C and H:C ratios to be determined and these will be compared to those obtained by aerosol mass spectrometry (AMS). In addition, the OA composition from the rainforest will be compared to other locations.

  4. Fatty acids as biomarkers for food web structure in the eastern North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Behrens, J.; Aluwihare, L.; Stephens, B. M.

    2015-12-01

    Resulting from a NSF funded REU program at Scripps Institution of Oceanography in 2015, this research utilized gas chromatography-mass spectrometry (GC-MS) to analyze the fatty acid composition of suspended particulate organic matter (POM) and zooplankton (ZP; primarily copepods). Samples analyzed for this study were collected simultaneously from surface waters approximately 9 miles off the coast of San Diego in June 2015. I was testing the hypothesis that essential fatty acids in ZP should reflect their diet, in particular, distinguishing contributions from a microbial versus traditional food web. Food web structure in this region of the ocean has been shown to be sensitive to climate change on inter-annual and longer timescales. Thus, a proxy that identifies restructuring of food webs would be useful for examining the response of ocean ecosystems to future climate change. Lipids were extracted from ZP and POM using a modified Bligh and Dyer method with sonication. Following saponification free fatty acids and other lipids were further purified using column chromatography. Polar functional groups in lipids were then methylated prior to GC-MS analysis. In addition, 2-dimensional GCxGC with time of flight MS was used to distinguish polyunsaturated fatty acid isomers. My poster will present initial findings of shared fatty acids of zooplankton and POM suspended material from the Northern Pacific collection site. Further research will be focused on analyzing the hydrogen isotope composition of fatty acids in zooplankton and suspended DOM obtained at the collection site to further characterize and increase certainty on the role of microbes and phytoplankton in the region's food-web to distinguish prokaryotic and eukaryotic sources.

  5. Anti-inertial lift in foams: a signature of the elasticity of complex fluids.

    PubMed

    Dollet, Benjamin; Aubouy, Miguel; Graner, François

    2005-10-14

    To understand the mechanics of a complex fluid such as a foam we propose a model experiment (a bidimensional flow around an obstacle) for which an external sollicitation is applied, and a local response is measured, simultaneously. We observe that an asymmetric obstacle (cambered airfoil profile) experiences a downwards lift, opposite to the lift usually known (in a different context) in aerodynamics. Correlations of velocity, deformations, and pressure fields yield a clear explanation of this inverse lift, involving the elasticity of the foam. We argue that such an inverse lift is likely common to complex fluids with elasticity. PMID:16241847

  6. Emerging properties of financial time series in the ``Game of Life''

    NASA Astrophysics Data System (ADS)

    Hernández-Montoya, A. R.; Coronel-Brizio, H. F.; Stevens-Ramírez, G. A.; Rodríguez-Achach, M.; Politi, M.; Scalas, E.

    2011-12-01

    We explore the spatial complexity of Conway’s “Game of Life,” a prototypical cellular automaton by means of a geometrical procedure generating a two-dimensional random walk from a bidimensional lattice with periodical boundaries. The one-dimensional projection of this process is analyzed and it turns out that some of its statistical properties resemble the so-called stylized facts observed in financial time series. The scope and meaning of this result are discussed from the viewpoint of complex systems. In particular, we stress how the supposed peculiarities of financial time series are, often, overrated in their importance.

  7. A 3-D Generalization of the Budyko Framework Captures the Mutual Interdependence Between Long-Term Mean Annual Precipitation, Actual and Potential Evapotranspiration

    NASA Astrophysics Data System (ADS)

    Carmona, A. M.; Poveda, G.

    2012-12-01

    We study the behavior of the 3-D parameter space defined by Φ =PET/P (so-called Aridity Index), Ψ =AET/P, and Ω =AET/PET, where P denotes mean annual precipitation, and PET and AET denote mean annual potential and actual evapotranspiration, respectively. Using information from the CLIMWAT 2.0 database (www.fao.org/nr/water/infores_databases_climwat.html) for P and PET, we estimate AET using both Budyko's and Turc's equations. Our results indicate that the well-known Budyko function that relates Φ vs.Ψ corresponds to a particular bi-dimensional cross-section of a broader coupling existing between Φ, Ψ and Ω (Figure 1a), and in turn of the mutual interdependence between P, PET and AET. The behavior of the three bi-dimensional projections are clearly parameterized by the remaining ortogonal parameter, such that: (i) the relation Φ vs. Ψ is defined by physically consistent varying values of Ω (Figure 1b); (ii) the relation Ω vs. Ψ is defined by physically consistent varying values of the Aridity Index,Φ (Figure 1c), and (iii) the relation Ω vs. Φ is defined by physically consistent varying values of Ψ (Figure 1d). Interestingly, we show that Φ and Ω are related by a power law, Φ~Ω-θ, with scaling exponent θ=1.15 (R2=0.91, n=3420) for the whole world (Figure 1d). Mathematical functions that model the three bi-dimensional projections and the surface defining the interdependence between Φ, Ψ and Ω will be presented. Our results provide a new framework to understand the coupling between the long-term mean annual water and energy balances in river basins, and the hydrological effects brought about by climate change, while taking into account the mutual interdependence between the three non-dimensional parameters Φ, Ψ and Ω, and in turn between P, PET and AET. Figure 1. (a) Three-dimensional rendering of sample values of Φ =PET/P (so-called Aridity Index), Ψ =AET/P, and Ω=AET/PET. Bi-dimensional projections of: (b) relation Φ vs.

  8. A hardware and software overview of the Delphi contiguity trigger

    SciTech Connect

    Darbo, G. ); Heck, B.W.; Wildman, J.M. )

    1991-04-01

    The contiguity processor of the Delphi detector, which is composed of 12 Fastbus modules (one for each TPC sector), is the main second-level track trigger component in the experiment. More than 3000 Mips of processing power are achieved by 4608 processing elements (PE) packed in specially designed ASIC IC's. High interconnectivity among PE's (bidimensional lattice) and a highly parallel algorithm (contiguity mask) allow a three-dimensional vertex reconstruction in less than 5{mu}s. In this paper an overview of the single instruction multiple data (SIMD) architecture, together with the programming language and the interactive debugging tools for the processor, are given.

  9. Digital Model of Fourier and Fresnel Quantized Holograms

    NASA Astrophysics Data System (ADS)

    Boriskevich, Anatoly A.; Erokhovets, Valery K.; Tkachenko, Vadim V.

    Some models schemes of Fourier and Fresnel quantized protective holograms with visual effects are suggested. The condition to arrive at optimum relationship between the quality of reconstructed images, and the coefficient of data reduction about a hologram, and quantity of iterations in the reconstructing hologram process has been estimated through computer model. Higher protection level is achieved by means of greater number both bi-dimensional secret keys (more than 2128) in form of pseudorandom amplitude and phase encoding matrixes, and one-dimensional encoding key parameters for every image of single-layer or superimposed holograms.

  10. Hysteretic mode exchange in the wake of two circular cylinders in tandem

    NASA Astrophysics Data System (ADS)

    Tasaka, Yuji; Kon, Seiji; Schouveiler, Lionel; Le Gal, Patrice

    2006-08-01

    Our experimental study is devoted to the analysis of the flow past two tandem circular cylinders near the vortex shedding threshold. A recent bidimensional numerical analysis of this flow [Mizushima and Suehiro, Phys. Fluids 17, 104107 (2005)] has predicted that the bifurcation diagram should become complex in the vicinity of the instability threshold. Subcritical and saddle node bifurcations that lead to hysteretic exchanges between two different modes of vortex shedding were detected for particular distances of separation of the cylinders. We present here visualizations and velocity measurements of this flow in a water channel that prove the robustness of the complexity of the bifurcation diagram in real flows.

  11. Performance analysis of parallel supernodal sparse LU factorization

    SciTech Connect

    Grigori, Laura; Li, Xiaoye S.

    2004-02-05

    We investigate performance characteristics for the LU factorization of large matrices with various sparsity patterns. We consider supernodal right-looking parallel factorization on a bi-dimensional grid of processors, making use of static pivoting. We develop a performance model and we validate it using the implementation in SuperLU-DIST, the real matrices and the IBM Power3 machine at NERSC. We use this model to obtain performance bounds on parallel computers, to perform scalability analysis and to identify performance bottlenecks. We also discuss the role of load balance and data distribution in this approach.

  12. Note: Background Oriented Schlieren as a diagnostics for airflow control by plasma actuators.

    PubMed

    Biganzoli, I; Capone, C; Barni, R; Riccardi, C

    2015-02-01

    Background Oriented Schlieren (BOS) is an optical technique sensitive to the first spatial derivative of the refractive index inside a light-transmitting medium. Compared to other Schlieren-like techniques, BOS is more versatile and allows to capture bi-dimensional gradients rather than just one spatial component. We propose to adopt BOS for studying the capabilities of surface dielectric barrier discharges to work like plasma actuators in flow control applications. The characteristics of the BOS we implemented at this purpose are discussed, together with few results concerning the ionic wind produced by the discharge in absence of an external airflow. PMID:25725896

  13. A far infrared/terahertz micromechanical sensor based on surface plasmons resonance

    NASA Astrophysics Data System (ADS)

    Hastanin, J.; Renotte, Y.; Fleury-Frenette, K.; Defise, J. M.; Habraken, S.

    2008-10-01

    This paper describes a new concept related to the bolometric micromechanical sensors for detecting far IR and THz radiation. We believe that this concept permits a low cost and ease of fabrication of large bi-dimensional array of sensors with an enhanced signal-to-noise ratio. The micromechanical sensor comprises a thermo-sensitive bi-material (multi-material) micro-cantilever beam with a selective absorber dedicated to far IR and THz radiation energy, and optical readout system based on surface plasmon resonance for detecting the bending of the micro-cantilever element. To increase the radiation detector sensitivity, the SPR phenomenon is used for cantilever deflection monitoring.

  14. Conditions for achieving ideal and Lambertian symmetrical solar concentrators.

    PubMed

    Luque, A; Lorenzo, E

    1982-10-15

    In this paper we are concerned with symmetrical bidimensional concentrators, and we prove that for a given source's angular extension a curve exists that divides the plane into two regions. No ideal concentrator can be found with its edges on the outer region and no Lambertian concentrator can be found with its edges on the inner region. A consequence of this theorem is that a concentrator is forced to cast some of the incident energy outside the collector to ensure its obtaining the maximum power. PMID:20396308

  15. Seed layer technique for high quality epitaxial manganite films

    NASA Astrophysics Data System (ADS)

    Graziosi, P.; Gambardella, A.; Calbucci, M.; O'Shea, K.; MacLaren, D. A.; Riminucci, A.; Bergenti, I.; Fugattini, S.; Prezioso, M.; Homonnay, N.; Schmidt, G.; Pullini, D.; Busquets-Mataix, D.; Dediu, V.

    2016-08-01

    We introduce an innovative approach to the simultaneous control of growth mode and magnetotransport properties of manganite thin films, based on an easy-to-implement film/substrate interface engineering. The deposition of a manganite seed layer and the optimization of the substrate temperature allows a persistent bi-dimensional epitaxy and robust ferromagnetic properties at the same time. Structural measurements confirm that in such interface-engineered films, the optimal properties are related to improved epitaxy. A new growth scenario is envisaged, compatible with a shift from heteroepitaxy towards pseudo-homoepitaxy. Relevant growth parameters such as formation energy, roughening temperature, strain profile and chemical states are derived.

  16. Pyroelectric Applications of the VDF-TrFE Copolymer

    NASA Technical Reports Server (NTRS)

    Simonne, J. J.; Bauer, Ph.; Audaire, L.; Bauer, F.

    1995-01-01

    VDF/TrFe pyroelectric sensors have now definitely reached the level of a product. Based on a bidimensional staring array, it can be considered as a whole system with a monolithic technology processed on a silicon substrate provided with the integrated read out circuit. The paper will describe the main procedure dealing with the elaboration of a 32 x 32 focal plane array developed, in the context of the PROMETHEUS PROCHIP European Program (EUREKA), as a passive infrared obstacle detection applied to automotive. Additional experimental data suggest that this microsystem could operate in space environment.

  17. Emerging properties of financial time series in the "Game of Life".

    PubMed

    Hernández-Montoya, A R; Coronel-Brizio, H F; Stevens-Ramírez, G A; Rodríguez-Achach, M; Politi, M; Scalas, E

    2011-12-01

    We explore the spatial complexity of Conway's "Game of Life," a prototypical cellular automaton by means of a geometrical procedure generating a two-dimensional random walk from a bidimensional lattice with periodical boundaries. The one-dimensional projection of this process is analyzed and it turns out that some of its statistical properties resemble the so-called stylized facts observed in financial time series. The scope and meaning of this result are discussed from the viewpoint of complex systems. In particular, we stress how the supposed peculiarities of financial time series are, often, overrated in their importance. PMID:22304152

  18. The double superficiality of the frontal image of the Turin Shroud

    NASA Astrophysics Data System (ADS)

    Fanti, Giulio; Maggiolo, Roberto

    2004-06-01

    Photographs of the back surface of the Turin Shroud were analysed to verify the existence of a double body image of a man. The body image is very faint and the background not uniform; i.e., the signal-to-noise ratio is lower than one. Therefore, image processing, developed ad hoc, was necessary to highlight body features. This was based on convolution with Gaussian filters, summation of images, and filtering in spatial frequency by direct and inverse bidimensional Fourier transformations. Body features were identified by template matching. The face and probably also the hands are visible on the back of the Turin Shroud, but not features related to the dorsal image.

  19. Third order nonlinear optical response exhibited by mono- and few-layers of WS2

    NASA Astrophysics Data System (ADS)

    Torres-Torres, Carlos; Perea-López, Néstor; Elías, Ana Laura; Gutiérrez, Humberto R.; Cullen, David A.; Berkdemir, Ayse; López-Urías, Florentino; Terrones, Humberto; Terrones, Mauricio

    2016-06-01

    In this work, strong third order nonlinear optical properties exhibited by WS2 layers are presented. Optical Kerr effect was identified as the dominant physical mechanism responsible for these third order optical nonlinearities. An extraordinary nonlinear refractive index together with an important contribution of a saturated absorptive response was observed to depend on the atomic layer stacking. Comparative experiments performed in mono- and few-layer samples of WS2 revealed that this material is potentially capable of modulating nonlinear optical processes by selective near resonant induced birefringence. We envision applications for developing all-optical bidimensional nonlinear optical devices.

  20. Motion of a two-degree-of-freedom structure in the presence of a fluidelastic force

    SciTech Connect

    Turbelin, G.; Porcher, G.; Gibert, R.J.

    1996-12-01

    The fluidelastic force induced by a confined flow in a bidimensional flow channel, has been determined by using a method which takes into account the dissipative effects by a linearizing of the pressure losses considered as boundary conditions. This force has been used to study the stability of a two-degree-of-freedom structure for several boundary conditions. The motion equation of the system can be solved with an iterative method, and a parametric study has been carried out. The results obtained show the appearance of a flutter instability which has been largely influenced by the position and the value of the pressure losses.

  1. Effective photoconductivity of exfoliated black phosphorus for optoelectronic switching under 1.55 μm optical excitation

    NASA Astrophysics Data System (ADS)

    Penillard, A.; Tripon-Canseliet, C.; Rosticher, M.; Maksimovic, I.; Liu, Z.; Géron, E.

    2016-01-01

    We present a microwave photoconductive switch based on exfoliated black phosphorus and strongly responding to a 1.55 μm optical excitation. According to its number of atomic layers, exfoliated black phosphorus presents unique properties for optoelectronic applications, like a tunable direct bandgap from 0.3 eV to 2 eV, strong mobilities, and strong conductivities. The switch shows a maximum ON/OFF ratio of 17 dB at 1 GHz, and 2.2 dB at 20 GHz under 1.55-μm laser excitation at 50 mW, never achieved with bidimensional materials.

  2. Evidence of cortical reorganization in hemiparetic patients

    SciTech Connect

    Brion, J.P.; Demeurisse, G.; Capon, A. )

    1989-08-01

    We studied the mechanisms underlying the recovery of motor function of the hand using a bidimensional xenon-133 inhalation technique to measure regional cerebral blood flow at rest and during the performance of a motor task (test condition). The regional cerebral blood flow patterns under rest and test conditions were compared in normal control and in stroke patients with either a cortico-subcortical or a deep-seated lesion. Functional recovery appears to depend upon cortical reorganization involving both hemispheres, particularly in both parietal regions in the subgroup of patients with cortico-subcortical lesions.

  3. Unsteady flow characteristics in the near-wake of a two-dimensional obstacle

    NASA Technical Reports Server (NTRS)

    Dyment, A.; Gryson, P.

    1984-01-01

    The influence of the characteristics of the boundary layer separation on the formation of vortices and alternate paths in the wake of a bidimensional obstacle at high Reynolds numbers was studied by ultra fast visualization system. It is shown that there are alternate paths for laminar and turbulent flows, with similar flow characteristics. It is found that emission of vortices does not change substantially when the flow passes from laminar to turbulent. A film with a time scale change of 10,000 times illustrates some of the discussed phenomena.

  4. A full 3D plane-wave-expansion model for 1-3 piezoelectric composite structures.

    PubMed

    Wilm, Mikaël; Ballandras, Sylvain; Laude, Vincent; Pastureaud, Thomas

    2002-09-01

    The plane-wave-expansion (PWE) approach dedicated to the simulation of periodic devices has been extended to 1-3 connectivity piezoelectric composite structures. The case of simple but actual piezoelectric composite structures is addressed, taking piezoelectricity, acoustic losses, and electrical excitation conditions rigorously into account. The material distribution is represented by using a bidimensional Fourier series and the electromechanical response is simulated using a Bloch-Floquet expansion together with the Fahmy-Adler formulation of the Christoffel problem. Application of the model to 1-3 connectivity piezoelectric composites is reported and compared to previously published analyses of this problem. PMID:12243182

  5. Optical beam steering using a 2D MEMS scanner

    NASA Astrophysics Data System (ADS)

    Pétremand, Yves; Clerc, Pierre-André; Epitaux, Marc; Hauffe, Ralf; Noell, Wilfried; de Rooij, N. F.

    2007-10-01

    This paper presents the design, fabrication and operation principle of an optical beam steerer for laser fiber coupling based on a MEMS device. The MEMS chip consists on a bi-dimensional movable platform based on uni-dimensional comb drive actuation. An optical lens is assembled onto the mobile platform to focus and steer the light comping from a laser diode and couple it into an optical fiber. Assembly of a complete system and measurements were performed and compared to simulation results. Both the trajectory of the MEMS and resonance frewquency measurements agree with the simulated ones.

  6. Contribution to the numerical study of turbulence in high intensity discharge lamps

    SciTech Connect

    Kaziz, S.; Ben Ahmed, R.; Helali, H.; Gazzah, H.; Charrada, K.

    2011-07-15

    We present in this paper a comparison between results obtained with a laminar and turbulent models for high-pressure mercury arc. The two models are based on the resolution of bidimensional time-dependent equations by a semi-implicit finite-element code. The numerical computation of turbulent model is solved with large eddy simulation model; this approach takes into account the various scales of turbulence by a filtering method on each scale. The results show the quantitative influence of turbulence on the flow fields and also the difference between laminar and turbulent effects on the dynamic thermal behaviour and on the characteristics of the discharge.

  7. Faithful test of nonlocal realism with entangled coherent states

    SciTech Connect

    Lee, Chang-Woo; Jeong, Hyunseok; Paternostro, Mauro

    2011-02-15

    We investigate the violation of Leggett's inequality for nonlocal realism using entangled coherent states and various types of local measurements. We prove mathematically the relation between the violation of the Clauser-Horne-Shimony-Holt form of Bell's inequality and Leggett's one when tested by the same resources. For Leggett inequalities, we generalize the nonlocal realistic bound to systems in Hilbert spaces larger than bidimensional ones and introduce an optimization technique that allows one to achieve larger degrees of violation by adjusting the local measurement settings. Our work describes the steps that should be performed to produce a self-consistent generalization of Leggett's original arguments to continuous-variable states.

  8. Width of the level at E sub x congruent 18 MeV in sup 5 Li

    SciTech Connect

    Arena, N.; Cavallaro, S. Istituto Nazionale di Fisica Nucleare, Sezione di Catania, Catania, Italy); D'Arrigo, A.; Fazio, G.; Giardina, G.; Italiano, A.; Herman, M.; Lombardi, M.

    1989-09-01

    The {alpha}{alpha} bidimensional spectra for the {sup 6}Li({sup 3}He, {alpha}{ital p}){sup 4}He reaction at 11, 13, and 14 MeV incident energy have been measured. The {sup 5}Li state at {ital E}{sub {ital x}}=(17.9{plus minus}0.4) MeV has been observed and its width has been determined as (3.5{plus minus}0.8) MeV. The excitation energy is in line with the shell-model calculations while the {Gamma} value is the first quantitative estimate of the width of the above state.

  9. Anti-Inertial Lift in Foams: A Signature of the Elasticity of Complex Fluids

    NASA Astrophysics Data System (ADS)

    Dollet, Benjamin; Aubouy, Miguel; Graner, François

    2005-10-01

    To understand the mechanics of a complex fluid such as a foam we propose a model experiment (a bidimensional flow around an obstacle) for which an external sollicitation is applied, and a local response is measured, simultaneously. We observe that an asymmetric obstacle (cambered airfoil profile) experiences a downwards lift, opposite to the lift usually known (in a different context) in aerodynamics. Correlations of velocity, deformations, and pressure fields yield a clear explanation of this inverse lift, involving the elasticity of the foam. We argue that such an inverse lift is likely common to complex fluids with elasticity.

  10. Nonsynchronous updating in the multiverse of cellular automata.

    PubMed

    Reia, Sandro M; Kinouchi, Osame

    2015-04-01

    In this paper we study updating effects on cellular automata rule space. We consider a subset of 6144 order-3 automata from the space of 262144 bidimensional outer-totalistic rules. We compare synchronous to asynchronous and sequential updatings. Focusing on two automata, we discuss how update changes destroy typical structures of these rules. Besides, we show that the first-order phase transition in the multiverse of synchronous cellular automata, revealed with the use of a recently introduced control parameter, seems to be robust not only to changes in update schema but also to different initial densities. PMID:25974442

  11. Nonsynchronous updating in the multiverse of cellular automata

    NASA Astrophysics Data System (ADS)

    Reia, Sandro M.; Kinouchi, Osame

    2015-04-01

    In this paper we study updating effects on cellular automata rule space. We consider a subset of 6144 order-3 automata from the space of 262144 bidimensional outer-totalistic rules. We compare synchronous to asynchronous and sequential updatings. Focusing on two automata, we discuss how update changes destroy typical structures of these rules. Besides, we show that the first-order phase transition in the multiverse of synchronous cellular automata, revealed with the use of a recently introduced control parameter, seems to be robust not only to changes in update schema but also to different initial densities.

  12. A comparison of locally adaptive multigrid methods: LDC, FAC and FIC

    NASA Technical Reports Server (NTRS)

    Khadra, Khodor; Angot, Philippe; Caltagirone, Jean-Paul

    1993-01-01

    This study is devoted to a comparative analysis of three 'Adaptive ZOOM' (ZOom Overlapping Multi-level) methods based on similar concepts of hierarchical multigrid local refinement: LDC (Local Defect Correction), FAC (Fast Adaptive Composite), and FIC (Flux Interface Correction)--which we proposed recently. These methods are tested on two examples of a bidimensional elliptic problem. We compare, for V-cycle procedures, the asymptotic evolution of the global error evaluated by discrete norms, the corresponding local errors, and the convergence rates of these algorithms.

  13. Optical correlators: systems and domains of applications

    NASA Astrophysics Data System (ADS)

    Dragulinescu, Andrei; Cojoc, Dan

    2005-08-01

    The paper presents the basic concepts of the optical correlators. In our knowledge, it is the first systematic presentation of the applications of optical correlators. The main three types of optical correlators: the optical correlator in incoherent light, the optical correlator in coherent light (VanderLugt) and the joint transform correlator are presented. The optical correlators are very powerll systems used for image recognition, that perform a correlation between a bidimensional function which represents a Scene that must be analyzed and another bidimensional function that contains information about the reference function. This correlation is optically realized by a Fourier transform between the two functions. The optical Correlators have found a lot of applications for image recognition and target detection in various fields, such as the military field, robotics, medical field, industry a.s.o. Among the various applications of the optical correlators we can mention: digital fingerprints identification, credit card security, antique scripts recognition, determination of the cosmic ships and satellites behavior, amelioration of cancer tests precision, quality control etc.

  14. Iterative fragmentation of cognitive maps in a visual imagery task.

    PubMed

    Fourtassi, Maryam; Hajjioui, Abderrazak; Urquizar, Christian; Rossetti, Yves; Rode, Gilles; Pisella, Laure

    2013-01-01

    It remains unclear whether spontaneous eye movements during visual imagery reflect the mental generation of a visual image (i.e. the arrangement of the component parts of a mental representation). To address this specificity, we recorded eye movements in an imagery task and in a phonological fluency (non-imagery) task, both consisting in naming French towns from long-term memory. Only in the condition of visual imagery the spontaneous eye positions reflected the geographic position of the towns evoked by the subjects. This demonstrates that eye positions closely reflect the mapping of mental images. Advanced analysis of gaze positions using the bi-dimensional regression model confirmed the spatial correlation of gaze and towns' locations in every single individual in the visual imagery task and in none of the individuals when no imagery accompanied memory retrieval. In addition, the evolution of the bi-dimensional regression's coefficient of determination revealed, in each individual, a process of generating several iterative series of a limited number of towns mapped with the same spatial distortion, despite different individual order of towns' evocation and different individual mappings. Such consistency across subjects revealed by gaze (the mind's eye) gives empirical support to theories postulating that visual imagery, like visual sampling, is an iterative fragmented processing. PMID:23874672

  15. 915 MHz microwave interstitial hyperthermia. Part II: Array of phase-monitored antennas.

    PubMed

    Camart, J C; Dubois, L; Fabre, J J; Vanloot, D; Chive, M

    1993-01-01

    In order to heat the whole volume of a tumour by microwave interstitial hyperthermia it is necessary to use an antenna array. The antenna modelization and the numerical solution of the bidimensional bioheat transfer equation allow determination of temperature evolution during a heating session. The calculations are taken for four antennas fed in phase and the theory is then proven by experiments on gel and on patients. Results are presented on cross-section heating patterns and their time evolution. Temperature distribution is calculated when feeding one antenna by a feeding current out of phase with the other currents. The phase difference value is optimized and it is then demonstrated that the heated volume is increased by successively feeding each antenna with an out-of-phase current. The time taken to feed each antenna one after the other is optimized. PMID:8515146

  16. MORPHOLOGY AND DYNAMICS OF THE LOW SOLAR CHROMOSPHERE

    SciTech Connect

    Woeger, F.; Uitenbroek, H.; Rimmele, T. R.; Wedemeyer-Boehm, S.

    2009-11-20

    The Interferometric Bidimensional Spectrometer (IBIS) installed at the Dunn Solar Telescope of the NSO/SP is used to investigate the morphology and dynamics of the lower chromosphere and the virtually non-magnetic fluctosphere below. The study addresses in particular the structure of magnetic elements that extend into these layers. We choose different quiet-Sun regions inside and outside the coronal holes. In inter-network regions with no significant magnetic flux contributions above the detection limit of IBIS, we find intensity structures with the characteristics of a shock wave pattern. The magnetic flux elements in the network are long lived and seem to resemble the spatially extended counterparts to the underlying photospheric magnetic elements. We suggest a modification to common methods to derive the line-of-sight magnetic field strength and explain some of the difficulties in deriving the magnetic field vector from observations of the fluctosphere.

  17. Context-specific attentional sampling: Intentional control as a pre-requisite for contextual control.

    PubMed

    Brosowsky, Nicholaus P; Crump, Matthew J C

    2016-08-01

    Recent work suggests that environmental cues associated with previous attentional control settings can rapidly and involuntarily adjust attentional priorities. The current study tests predictions from adaptive-learning and memory-based theories of contextual control about the role of intentions for setting attentional priorities. To extend the empirical boundaries of contextual control phenomena, and to determine whether theoretical principles of contextual control are generalizable we used a novel bi-dimensional stimulus sampling task. Subjects viewed briefly presented arrays of letters and colors presented above or below fixation, and identified specific stimuli according to a dimensional (letter or color) and positional cue. Location was predictive of the cued dimension, but not the position or identity. In contrast to previous findings, contextual control failed to develop through automatic, adaptive-learning processes. Instead, previous experience with intentionally changing attentional sampling priorities between different contexts was required for contextual control to develop. PMID:27500654

  18. Acoustic behavior of ordered droplets in a liquid: a phase space approach.

    PubMed

    Rivera, A L; Palomino, M R; de Icaza, M; Lozada-Cassou, M; Castaño, V M

    2005-03-01

    The transmission of an acoustical signal through a spatial arrangement consisting of a bidimensional crystal of droplets (liquid spheres) immersed into another liquid is analyzed. As a first approximation, the paraxial case is solved by considering a set of acoustical lenses which allow us to model the effect of each droplet on the signal. An expression for the Wigner distribution function that lets us evaluate the corresponding image, diffraction pattern, and even the output signal of any given paraxial input signal to that crystalline substrate is obtained, with particular emphasis on the case of an incoming plane wave. To solve the nonparaxial situation, a generalization of the concept of focal distance interpreting every sphere as a superposition of concentric rings of different radius, which permits us to find a general expression for the Wigner distribution function is proposed. PMID:15903601

  19. PHAROS: a spectrometer-on-a-chip for digital radiology systems with spectral detection

    NASA Astrophysics Data System (ADS)

    Cadeddu, S.; Caredda, D.; Caria, M.; Lai, A.; Randaccio, P.

    2002-02-01

    When a beam of X-rays crosses an object, its spectrum is modified depending on both the density and effective atomic number of the material. We describe an integrated (VLSI) spectrometer used in a digital radiology system for performing spectral analysis of the detected X-rays. It integrates 16 independent channels and gives seven bits of energy resolution. This permits the distinction between tissues featuring small differences in effective atomic number, e.g. micro-calcifications and fat cysts, which have the same contrast in a normal radiography. The integrated circuit services a row of solid-state detectors that can travel along the specimen in the radiology system in perpendicular directions, so that bi-dimensional images can be recorded. The circuit performs pulse height analysis and stores the spectral distribution of the detected photons. The circuit is described and its performance analyzed.

  20. Impact of molecular diffusion on the CO2 distribution and the temperature in the mesosphere

    NASA Astrophysics Data System (ADS)

    Chabrillat, Simon; Kockarts, Gaston; Fonteyn, Dominique; Brasseur, Guy

    2002-08-01

    Modelling the energy budget in the mesosphere and lower thermosphere requires a precise evaluation of CO2 distribution in this region. This distribution is primarily determined by competition between vertical eddy diffusion and molecular diffusion. A simple algorithm is proposed to take into account both processes, at all altitudes. Using the SOCRATES bi-dimensional model of the middle atmosphere, we show that molecular diffusion has a direct impact on CO2 vertical distribution down to approximately 80 km altitude, i.e. well into the mesosphere and below the turbopause altitude. A sensitivity study with regard to different aeronomical processes shows that molecular diffusion has the deepest influence in the mesospheric polar night region. Our model shows that molecular diffusion of CO2 is responsible for a polar night mesopause 12 K warmer than if this process was neglected. Hence, dynamical models should take this process in account across the whole mesospheric altitude range.

  1. MAGELLAN: High resolution spectroscopy at FUV and EUV wavelengths

    NASA Technical Reports Server (NTRS)

    Grewing, M.; Alighieri, S. D.; Burton, W.; Coleman, C. I.; Hoekstra, R.; Jamar, C.; Labeque, A.; Laurent, C.; Vidal-Madjar, A.; Rafanelli, P.

    1982-01-01

    The aim of ESA's MAGELLAN mission is to provide high resolution spectra of celestial sources down to sixteenth magnitude over the extreme ultraviolet wavelength range (between 50 and 140 nm). This range extends from studies of interstellar matter in the disc and halo of this and other galaxies, to stellar envelopes, hot and evolved stars, clusters, intergalactic matter, nuclei of galaxies, quasars, and, finally, planets and satellites. The instrument has a nonconventional optical design using only one reflecting surface; a high groove density concave grating collects the star light, diffracts it and focuses its spectrum into a bidimensional windowless detector operated in a photon counting mode. The slitless configuration provides the spectra of all the sources (point like and extended) in the field of view of the grating. This field of view is limited by a grid collimator to reduce the diffuse background, the stray light and the probability of overlapping spectra in crowded fields.

  2. Hydrolysis of GTP associated with the formation of tubulin oligomers is involved in microtubule nucleation.

    PubMed Central

    Carlier, M F; Didry, D; Pantaloni, D

    1997-01-01

    Hydrolysis of GTP is known to accompany microtubule assembly. Here we show that hydrolysis of GTP is also associated with the formation of linear oligomers of tubulin, which are precursors (prenuclei) in microtubule assembly. The hydrolysis of GTP on these linear oligomers inhibits the lateral association of GTP-tubulin that leads to the formation of a bidimensional lattice. Therefore GTP hydrolysis interferes with the nucleation of microtubules. Linear oligomers are also formed in mixtures of GTP-tubulin and GDP-tubulin. The hydrolysis of GTP associated with heterologous interactions between GTP-tubulin and GDP-tubulin in the cooligomer takes place at a threefold faster rate than upon homologous interactions between GTP-tubulins. The implication of these results in a model of vectorial GTP hydrolysis in microtubule assembly is discussed. Images FIGURE 7 PMID:9199805

  3. Sunitinib in relapsed or refractory diffuse large B-cell lymphoma: a clinical and pharmacodynamic phase II multicenter study of the NCIC Clinical Trials Group

    PubMed Central

    Buckstein, Rena; Kuruvilla, John; Chua, Neil; Lee, Christina; Macdonald, David A; Al-Tourah, Abdulwahab J; Foo, Alison H; Walsh, Wendy; Ivy, S Percy; Crump, Michael; Eisenhauer, Elizabeth A

    2011-01-01

    There are limited effective therapies for most patients with relapsed diffuse large B-cell lymphoma (DLBCL). We conducted a phase II trial of the multi-targeted vascular endothelial growth factor receptor (VEGFR) kinase inhibitor, sunitinib, 37.5 mg given orally once daily in adult patients with relapsed or refractory DLBCL. Of 19 enrolled patients, 17 eligible patients were evaluable for toxicity and 15 for response. No objective responses were seen and nine patients achieved stable disease (median duration 3.4 months). As a result, the study was closed at the end of the first stage. Grades 3—4 neutropenia and thrombocytopenia were observed in 29% and 35%, respectively. There was no relationship between change in circulating endothelial cell numbers (CECs) and bidimensional tumor burden over time. Despite some activity in solid tumors, sunitinib showed no evidence of response in relapsed/refractory DLBCL and had greater than expected hematologic toxicity. PMID:21463120

  4. Application of computed tomography for supernumerary teeth location in pediatric dentistry.

    PubMed

    Raupp, Suziane; Kramer, Paulo Floriani; de Oliveira, Helena Willhelm; da Rosa, Francinne Miranda; Faraco, Italo Medeiros

    2008-01-01

    Conventional radiographs provide bi-dimensional images of three-dimensional structures limiting optimal treatment planning. To overcome this deficiency, Computed Tomography (CT) has been used as a diagnostic method in Medicine and Dentistry. CT allows for supernumerary teeth location, the establishment of positional relations with other teeth, and the assessment of surrounding bone thickness; thus, facilitating surgical access and technique choice while reducing the procedure time, of great importance in pediatric dental care. The aim of this study was to present the possibility of applying CT for supernumerary teeth location, through the case report of a five-year-old female patient presenting two supernumerary teeth in the anterior palatal area. In conclusion, CT appears to be an excellent image diagnostic method for locating unerupted supernumerary teeth, providing precise information for planning and performing the surgical approach, while reducing operatory time and post-operatory complications; factors of extreme importance when treating young children. PMID:18767456

  5. Developing and improving a scanning system for dosimetric applications

    SciTech Connect

    Perez, P.; Galvan, V.; Castellanoa, G.; Valente, M.

    2010-08-04

    Radiotherapy is nowadays one of the most used techniques for the treatment of different pathologies, particularly cancer diseases. The accuracy regarding the application of these treatments, which are planned according to patient information, depends mainly on the dosimetric measurements of absorbed dose within irradiated tissues. The present work is devoted to the study, design and construction of an original device capable of performing visible light transmission measurements in order to analyze Fricke gel dosimeters. Furthermore, a suitable bi-dimensional positioning system along with a dedicated control system and image processing software has been adapted to the dosimetric device in order to perform 2D dose mapping. The obtained results confirm the feasibility of the proposed method, therefore suggesting its potentiality for clinical applications.

  6. NONPOTENTIALITY OF CHROMOSPHERIC FIBRILS IN NOAA ACTIVE REGIONS 11092 AND 9661

    SciTech Connect

    Jing Ju; Yuan Yuan; Xu Yan; Wang Haimin; Reardon, Kevin; Wiegelmann, Thomas E-mail: yy46@njit.edu E-mail: haimin@flare.njit.edu E-mail: wiegelmann@linmpi.mpg.de

    2011-10-01

    In this paper, we present a method to automatically segment chromospheric fibrils from H{alpha} observations and further identify their orientation. We assume that chromospheric fibrils are aligned with the magnetic field. By comparing the orientation of the fibrils with the azimuth of the embedding chromospheric magnetic field extrapolated from a potential field model, the shear angle, a measure of nonpotentiality, along the fibrils is readily deduced. Following this approach, we make a quantitative assessment of the nonpotentiality of fibrils in two NOAA active regions (ARs): (1) the relatively simple AR 11092, observed with very high resolution by Interferometric Bidimensional Spectrometer, and (2) a {beta}-{gamma}-{delta} AR 9661, observed with median resolution by Big Bear Solar Observatory before and after an X1.6 flare.

  7. How large grains increase bulk friction in bi-disperse granular chute flows

    NASA Astrophysics Data System (ADS)

    Staron, Lydie; Phillips, Jeremy C.

    2016-07-01

    In this contribution, we apply contact dynamics discrete simulations to explore how the mechanical properties of simple bi-dimensional granular chute flows are affected by the existence of two grain sizes. Computing partial stress tensors for the phases of small and large grains, we show that the phase of large grain exhibits a much larger shear strength than the phase of small grains. This difference translates in terms of the flow internal friction: adopting the μ (I) dependence to describe the flow frictional properties, we establish that the flow mean friction coefficient increases with the volume fraction of large grains. Hence, while the presence of large grains may induce lubrication in 3D unconfined flows due to the self-channelisation and levées formation, the effect of large grains on the bulk properties is to decrease the flow mobility.

  8. Stereotyping by omission: eliminate the negative, accentuate the positive.

    PubMed

    Bergsieker, Hilary B; Leslie, Lisa M; Constantine, Vanessa S; Fiske, Susan T

    2012-06-01

    Communicators, motivated by strategic self-presentation, selectively underreport negative content in describing their impressions of individuals and stereotypes of groups, particularly for targets whom they view ambivalently with respect to warmth and competence. Communicators avoid overtly inaccurate descriptions, preferring to omit negative information and emphasize positive information about mixed individual targets (Study 1). With more public audiences, communicators increasingly prefer negativity omission to complete accuracy (Study 2), a process driven by self-presentation concerns (Study 3) and moderated by bidimensional ambivalence. Similarly, in an extension of the Princeton Trilogy studies, reported stereotypes of ethnic and national outgroups systematically omitted negative dimensions over 75 years--as anti-prejudice norms intensified--while neutral and positive stereotype dimensions remained constant (Study 4). Multiple assessment methods confirm this stereotyping-by-omission phenomenon (Study 5). Implications of negativity omission for innuendo and stereotype stagnation are discussed. PMID:22448889

  9. Re-examining the role of attitude in information system acceptance: a model from the satisfaction-dissatisfaction perspective

    NASA Astrophysics Data System (ADS)

    Guo, Bin; Zhou, Shasha

    2016-05-01

    This study attempts to re-examine the role of attitude in voluntary information system (IS) acceptance and usage, which has often been discounted in the previous technology acceptance research. We extend the unidimensional view of attitude into a bidimensional one, because of the simultaneous existence of both positive and negative evaluation towards IS in technology acceptance behaviour. In doing so, attitude construct is divided into two components: satisfaction as the positive attitudinal component and dissatisfaction as the negative attitudinal component. We argue that satisfaction and dissatisfaction will interactively affect technology usage intention. Besides, we explore the predictors of satisfaction and dissatisfaction based on the disconfirmation theory. Empirical results from a longitudinal study on bulletin board system (BBS) usage confirm the interaction effect of satisfaction and dissatisfaction on usage intention. Moreover, perceived task-related value has a significant effect on satisfaction, while perceived personal value has a significant effect on dissatisfaction. We also discuss the theoretical and managerial implications of our findings.

  10. Hope and General Self-efficacy: Two Measures of the Same Construct?

    PubMed

    Zhou, Mingming; Kam, Chester Chun Seng

    2016-07-01

    The aim of this study was to test the extent to which hope measure is equivalent to general self-efficacy measure. Questionnaire data on these two constructs and other external variables were collected from 199 Chinese college students. The factor analytic results suggested that hope and self-efficacy items measured the same construct. The unidimensional model combining hope items and GSE items fit the data as well as the bidimensional model, indicating that their corresponding items measured the same underlying construct. Further analyses showed that hope and GSE did not correlate with external variables differently in a systematic manner. Most of these correlational differences were non-significant and negligible. These findings suggested that the literatures studying GSE and hope could be considered to be integrated and that researchers need to recognize and acknowledge the conceptual and operational similarities among these constructs in the literature. PMID:26761605

  11. Multi-focus parallel detection of fluorescent molecules at picomolar concentration with photonic nanojets arrays

    SciTech Connect

    Ghenuche, Petru; Torres, Juan de; Ferrand, Patrick; Wenger, Jérôme

    2014-09-29

    Fluorescence sensing and fluorescence correlation spectroscopy (FCS) are powerful methods to detect and characterize single molecules; yet, their use has been restricted by expensive and complex optical apparatus. Here, we present a simple integrated design using a self-assembled bi-dimensional array of microspheres to realize multi-focus parallel detection scheme for FCS. We simultaneously illuminate and collect the fluorescence from several tens of microspheres, which all generate their own photonic nanojet to efficiently excite the molecules and collect the fluorescence emission. Each photonic nanojet contributes to the global detection volume, reaching FCS detection volumes of several tens of femtoliters while preserving the fluorescence excitation and collection efficiencies. The microspheres photonic nanojets array enables FCS experiments at low picomolar concentrations with a drastic reduction in apparatus cost and alignment constraints, ideal for microfluidic chip integration.

  12. Chaotic dynamics of dilute thermal atom clouds on stationary optical Bessel beams

    NASA Astrophysics Data System (ADS)

    Castañeda, J. A.; Pérez-Pascual, R.; Jáuregui, R.

    2013-07-01

    We characterize the semiclassical dynamics of dilute thermal atom clouds located in three-dimensional optical lattices generated by stationary optical Bessel beams. The dynamics of the cold atoms is explored in the quasi-Hamiltonian regime that arises using laser beams with far-off resonance detuning. Although the transverse structure of Bessel beams exhibits a complex topological structure, it is found that the longitudinal motion along the main propagation axis of the beam is the detonator of a high sensitivity of the atoms' motion to the initial conditions. This effect would not be properly described by bidimensional models. We show that an experimental implementation can be highly simplified by an analysis of the behaviour of the dynamical system under scale transformations. Experimentally feasible signatures of the chaotic dynamics of the atom clouds are also identified.

  13. Nonextraction treatment of severe crowding with the aid of corticotomy-assisted orthodontics.

    PubMed

    Aljhani, Ali S; Zawawi, Khalid H

    2012-01-01

    THIS PAPER ILLUSTRATES THE COMBINED NONEXTRACTION ORTHODONTIC TREATMENT WITH THE CORTICOTOMY TECHNIQUE IN AN ADULT PATIENT (AGE: 25 years and 3 months) with severely crowded arches to accelerate tooth movement and shorten the treatment time. Both her upper lateral incisors were congenitally absent and both upper central incisors' roots were short. Initial fixed orthodontic appliances (bidimensional) were bonded and one week later buccal and lingual corticotomy with alveolar augmentation procedure in the maxilla and mandible was performed. Orthodontic activation to level and align and unravel the crowding was performed every two weeks. The total treatment time was 8 months with no adverse effects observed at the end of active treatment. The addition of the decortication procedure to the conventional orthodontic therapy decreased the duration of treatment significantly. Successful alignment of both arches with ideal overbite and overjet as well as adequate occlusion was achieved. PMID:22848854

  14. Nonextraction Treatment of Severe Crowding with the Aid of Corticotomy-Assisted Orthodontics

    PubMed Central

    Aljhani, Ali S.; Zawawi, Khalid H.

    2012-01-01

    This paper illustrates the combined nonextraction orthodontic treatment with the corticotomy technique in an adult patient (age: 25 years and 3 months) with severely crowded arches to accelerate tooth movement and shorten the treatment time. Both her upper lateral incisors were congenitally absent and both upper central incisors' roots were short. Initial fixed orthodontic appliances (bidimensional) were bonded and one week later buccal and lingual corticotomy with alveolar augmentation procedure in the maxilla and mandible was performed. Orthodontic activation to level and align and unravel the crowding was performed every two weeks. The total treatment time was 8 months with no adverse effects observed at the end of active treatment. The addition of the decortication procedure to the conventional orthodontic therapy decreased the duration of treatment significantly. Successful alignment of both arches with ideal overbite and overjet as well as adequate occlusion was achieved. PMID:22848854

  15. Westernization, intuitive eating, and BMI: an exploration of Jordanian adolescents.

    PubMed

    Wirtz, Amanda L; Madanat, Hala N

    The purpose of this study was to validate the Arabic-version of the adapted Marin Bidimensional Acculturation Scale and investigate the relationship between Westernization, intuitive eating, and body mass index (BMI) in a sample of Jordanian female adolescents. A total of 199 subjects between the ages of 11-18 were surveyed. Participants who scored higher on the Arabic domain exhibited higher Intuitive Eating Scale (IES) intrinsic subscale scores (r = 0.147, P = 0.048) suggesting that those who are more orientated toward Arabic culture may respond more naturally to physical hunger cues than their more Westernized counterparts. Reinforcing intuitive eating attitudes and behaviors and emphasizing body ideals resonant with the Arabic culture may propagate the continuation of intuitive eating in this population, potentially reducing the risk of obesity and other nutrition-related non-communicable diseases. PMID:23896036

  16. A numerical study of the supply mode effects on high-pressure mercury discharge lamp dynamic thermal behavior

    SciTech Connect

    Kaziz, S.; Ahmed, R. Ben; Araoud, Z.; Gazzah, M.H.; Charrada, K.; Said, R.

    2005-06-15

    This paper presents a numerical study of the dynamic behavior of high-pressure mercury discharge lamp as a function of supply mode. Bidimensional time-dependent equations have been solved by using a semi-implicit finite-element code. The model has been developed in the frame of the local thermodynamic equilibrium hypothesis. After validation by using experimental data from the literature, this model was applied to analyze the effects of some key parameters such as frequency for an ac arc current and the ratio cycle parameter for square arc-current wave form on the convective process. The results obtained have been used to analyze the dynamic thermal behavior of high-pressure mercury plasma (pressure equal to 0.3 MPa) working under currents widely different in frequency and wave form.

  17. Measuring science or religion? A measurement analysis of the National Science Foundation sponsored science literacy scale 2006-2010.

    PubMed

    Roos, J Micah

    2014-10-01

    High scientific literacy is widely considered a public good. Methods of assessing public scientific knowledge or literacy are equally important. In an effort to measure lay scientific literacy in the United States, the National Science Foundation (NSF) science literacy scale has been a part of the last three waves of the General Social Survey. However, there has been debate over the validity of some survey items as indicators of science knowledge. While many researchers treat the NSF science scale as measuring a single dimension, previous work (Bann and Schwerin, 2004; Miller, 1998, 2004) suggests a bidimensional structure. This paper hypothesizes and tests a new measurement model for the NSF science knowledge scale and finds that two items about evolution and the big bang are more measures of a religious belief dimension termed "Young Earth Worldview" than they are measures of scientific knowledge. Results are replicated in seven samples. PMID:23825273

  18. Effect of adiabatic square ribs on natural convection in an asymmetrically heated channel

    NASA Astrophysics Data System (ADS)

    Abidi-Saad, Aissa; Kadja, Mahfoud; Popa, Catalin; Polidori, Guillaume

    2016-06-01

    A 2-D numerical simulation is carried out to investigate the effect of two adiabatic square ribs on laminar flow and heat transfer in an asymmetrically heated channel. The two ribs are symmetrically located on each wall, exactly above the heating zone. The computational procedure is made by solving the unsteady bi-dimensional continuity, momentum and energy equations with the finite volume method. The investigations focused more specifically on the influence of ribs sizes on the flow structure and heat transfer enhancement. The results showed that the variation of ribs sizes significantly alters the heat transfer and fluid flow distribution along the channel, especially in the vicinity of protrusions. Also, the results show that streamlines, isotherms, and the number, sizes and formation of vortex structures inside the channel strongly depend on the size of protrusions. The changes in heat transfer parameters have also been presented.

  19. Scanning in biomedical imaging: from classical devices to handheld heads and micro-systems

    NASA Astrophysics Data System (ADS)

    Duma, Virgil-Florin

    2014-01-01

    We review some of the most important scanning systems that are competitive in high-end biomedical imaging applications such as Optical Coherence Tomography (OCT), but also Confocal Microscopy (CM) or multiphoton microscopy. Both 1-D (uni-dimensional) and 2-D (bi-dimensional) scanning systems are considered. The paper discusses different scanners, including polygon mirror, galvanometer-based and Risley prisms. Their configurations and characteristics, as well some of our contributions in the domain are presented. The tendency of applying them into special designs such as handheld scanning probes and endoscopes - the latter with MEMS (Micro-Electro-Mechanical Systems) and micro-systems is pointed out. A discussion on further advancements of scanning technology in biomedical applications in general and in OCT in particular concludes the study.

  20. Acoustic behavior of ordered droplets in a liquid: A phase space approach

    SciTech Connect

    Rivera, A.L.; Lozada-Cassou, M.; Palomino, M.R.; Icaza, M. de; Castano, V.M.

    2005-03-01

    The transmission of an acoustical signal through a spatial arrangement consisting of a bidimensional crystal of droplets (liquid spheres) immersed into another liquid is analyzed. As a first approximation, the paraxial case is solved by considering a set of acoustical lenses which allow us to model the effect of each droplet on the signal. An expression for the Wigner distribution function that lets us evaluate the corresponding image, diffraction pattern, and even the output signal of any given paraxial input signal to that crystalline substrate is obtained, with particular emphasis on the case of an incoming plane wave. To solve the nonparaxial situation, a generalization of the concept of focal distance interpreting every sphere as a superposition of concentric rings of different radius, which permits us to find a general expression for the Wigner distribution function is proposed.

  1. Dispersion analysis and measurement of circular cylindrical wedge-like acoustic waveguides.

    PubMed

    Yu, Tai-Ho

    2015-09-01

    This study investigated the propagation of flexural waves along the outer edge of a circular cylindrical wedge, the phase velocities, and the corresponding mode displacements. Thus far, only approximate solutions have been derived because the corresponding boundary-value problems are complex. In this study, dispersion curves were determined using the bi-dimensional finite element method and derived through the separation of variables and the Hamilton principle. Modal displacement calculations clarified that the maximal deformations appeared at the outer edge of the wedge tip. Numerical examples indicated how distinct thin-film materials deposited on the outer surface of the circular cylindrical wedge influenced the dispersion curves. Additionally, dispersion curves were measured using a laser-induced guided wave, a knife-edge measurement scheme, and a two-dimensional fast Fourier transform method. Both the numerical and experimental results correlated closely, thus validating the numerical solution. PMID:26074457

  2. Neuromorphic silicon neuron circuits.

    PubMed

    Indiveri, Giacomo; Linares-Barranco, Bernabé; Hamilton, Tara Julia; van Schaik, André; Etienne-Cummings, Ralph; Delbruck, Tobi; Liu, Shih-Chii; Dudek, Piotr; Häfliger, Philipp; Renaud, Sylvie; Schemmel, Johannes; Cauwenberghs, Gert; Arthur, John; Hynna, Kai; Folowosele, Fopefolu; Saighi, Sylvain; Serrano-Gotarredona, Teresa; Wijekoon, Jayawan; Wang, Yingxue; Boahen, Kwabena

    2011-01-01

    Hardware implementations of spiking neurons can be extremely useful for a large variety of applications, ranging from high-speed modeling of large-scale neural systems to real-time behaving systems, to bidirectional brain-machine interfaces. The specific circuit solutions used to implement silicon neurons depend on the application requirements. In this paper we describe the most common building blocks and techniques used to implement these circuits, and present an overview of a wide range of neuromorphic silicon neurons, which implement different computational models, ranging from biophysically realistic and conductance-based Hodgkin-Huxley models to bi-dimensional generalized adaptive integrate and fire models. We compare the different design methodologies used for each silicon neuron design described, and demonstrate their features with experimental results, measured from a wide range of fabricated VLSI chips. PMID:21747754

  3. Analysis of brain activity and response during monoscopic and stereoscopic visualization

    NASA Astrophysics Data System (ADS)

    Calore, Enrico; Folgieri, Raffaella; Gadia, Davide; Marini, Daniele

    2012-03-01

    Stereoscopic visualization in cinematography and Virtual Reality (VR) creates an illusion of depth by means of two bidimensional images corresponding to different views of a scene. This perceptual trick is used to enhance the emotional response and the sense of presence and immersivity of the observers. An interesting question is if and how it is possible to measure and analyze the level of emotional involvement and attention of the observers during a stereoscopic visualization of a movie or of a virtual environment. The research aims represent a challenge, due to the large number of sensorial, physiological and cognitive stimuli involved. In this paper we begin this research by analyzing possible differences in the brain activity of subjects during the viewing of monoscopic or stereoscopic contents. To this aim, we have performed some preliminary experiments collecting electroencephalographic (EEG) data of a group of users using a Brain- Computer Interface (BCI) during the viewing of stereoscopic and monoscopic short movies in a VR immersive installation.

  4. 1024 pixels single photon imaging array for 3D ranging

    NASA Astrophysics Data System (ADS)

    Bellisai, S.; Guerrieri, F.; Tisa, S.; Zappa, F.; Tosi, A.; Giudice, A.

    2011-01-01

    Three dimensions (3D) acquisition systems are driving applications in many research field. Nowadays 3D acquiring systems are used in a lot of applications, such as cinema industry or in automotive (for active security systems). Depending on the application, systems present different features, for example color sensitivity, bi-dimensional image resolution, distance measurement accuracy and acquisition frame rate. The system we developed acquires 3D movie using indirect Time of Flight (iTOF), starting from phase delay measurement of a sinusoidally modulated light. The system acquires live movie with a frame rate up to 50frame/s in a range distance between 10 cm up to 7.5 m.

  5. In vitro imaging of remaining dentin and pulp chamber by optical coherence tomography: comparison between 850 and 1280 nm

    NASA Astrophysics Data System (ADS)

    Fonsêca, Déborah D. D.; Kyotoku, Bernardo B. C.; Maia, Ana M. A.; Gomes, Anderson S. L.

    2009-03-01

    We report the application of optical coherence tomography (OCT) to generate images of the remaining dentin and pulp chamber of in vitro human teeth. Bidimensional images of remaining dentin and of the pulp chamber were obtained parallel to the long axis of the teeth, by two OCT systems operating around 1280 and 850 nm, and compared to tomography images using the i-CAT® Cone Beam Volumetric Tomography system as the gold standard. The results demonstrated the efficacy of the OCT technique; furthermore, the wavelength close to 1280 nm presented greater penetration depth in the dentine than 850 nm, as expected from scattering and absorption coefficients. The OCT technique has great potential to be used on clinical practice, preventing accidental exposure of the pulp and promoting preventive restoration treatment.

  6. Non-Gaussian behavior in jamming / unjamming transition in dense granular materials

    NASA Astrophysics Data System (ADS)

    Atman, A. P. F.; Kolb, E.; Combe, G.; Paiva, H. A.; Martins, G. H. B.

    2013-06-01

    Experiments of penetration of a cylindrical intruder inside a bidimensional dense and disordered granular media were reported recently showing the jamming / unjamming transition. In the present work, we perform molecular dynamics simulations with the same geometry in order to assess both kinematic and static features of jamming / unjamming transition. We study the statistics of the particles velocities at the neighborhood of the intruder to evince that both experiments and simulations present the same qualitative behavior. We observe that the probability density functions (PDF) of velocities deviate from Gaussian depending on the packing fraction of the granular assembly. In order to quantify these deviations we consider a q-Gaussian (Tsallis) function to fit the PDF's. The q-value can be an indication of the presence of long range correlations along the system. We compare the fitted PDF's obtained with those obtained using the stretched exponential, and sketch some conclusions concerning the nature of the correlations along a granular confined flow.

  7. High-quality molecular-beam epitaxial regrowth of (Al,Ga)As on Se-modified (100) GaAs surfaces

    NASA Astrophysics Data System (ADS)

    Turco, F. S.; Sandroff, C. J.; Hwang, D. M.; Ravi, T. S.; Tamargo, M. C.

    1990-08-01

    It is shown that high-quality molecular-beam epitaxial (MBE) regrowth of (Al,Ga)As on GaAs can be achieved by chemically passivating the GaAs surface ex situ prior to regrowth with aqueous selenium reagents. Reflection high-energy electron diffraction intensity oscillations show the bidimensional character of the regrowth and high-resolution transmission electron microscopy reveals defect-free regrown interfaces. Photoluminescence intensity from the Se-treated GaAs surfaces on which Al0.5Ga0.5 As is regrown rivals that from an all in situ grown AlGaAs/GaAs interface. The high quality of these regrown interfaces could be attributed to the thermally and chemically stable selenium and oxygen phases that remain bound to GaAs under MBE conditions.

  8. Tunable superconductivity in decorated graphene

    NASA Astrophysics Data System (ADS)

    Han, Zheng; Allain, Adrien; Marty, Laetitia; Bendiab, Nedjma; Toulemonde, Pierre; Strobel, Pierre; Coraux, Johann; Bouchiat, Vincent

    2013-03-01

    Graphene offers an exposed bidimensional gas of high mobility charge carriers with gate tunable density. Its chemical inertness offers an outstanding platform to explore exotic 2D superconductivity. Superconductivity can be induced in graphene by means of proximity effect (by depositing a set of superconducting metal clusters such as lead or tin nanoparticles). The influence of decoration material, density or particles and disorder of graphene will be discussed. In the case of disordered graphene, Tin decoration leads to a gate-tunable superconducting-to-insulator quantum phase transition. Superconductivity in graphene is also expected to occur under strong charge doping (induced either by gating or under chemical decoration, in analogy with graphite intercalated compounds). I will also show preliminary results showing the influence of Calcium intercalation of few layer graphene and progress toward the demonstration of intrinsic superconductivity in such systems. Work supported by EU GRANT FP7-NMP GRENADA.

  9. Observation of a phononic Mollow triplet in a multimode hybrid spin-nanomechanical system

    PubMed Central

    Pigeau, B.; Rohr, S.; Mercier de Lépinay, L.; Gloppe, A.; Jacques, V.; Arcizet, O.

    2015-01-01

    Reminiscent of the bound character of a qubit's dynamics confined on the Bloch sphere, the observation of a Mollow triplet in the resonantly driven qubit fluorescence spectrum represents one of the founding signatures of quantum electrodynamics. Here we report on its observation in a hybrid spin-nanomechanical system, where a nitrogen-vacancy spin qubit is magnetically coupled to the vibrations of a silicon carbide nanowire. A resonant microwave field turns the originally parametric hybrid interaction into a resonant process, where acoustic phonons are now able to induce transitions between the dressed qubit states, leading to synchronized spin-oscillator dynamics. We further explore the vectorial character of the hybrid coupling to the bidimensional deformations of the nanowire. The demonstrated microwave assisted synchronization of the spin-oscillator dynamics opens novel perspectives for the exploration of spin-dependent forces, the key ingredient for quantum state transfer. PMID:26477639

  10. Self-construal, mental distress, and family relations: a mediated moderation analysis with Asian American adolescents.

    PubMed

    Liu, Freda F; Goto, Sharon G

    2007-04-01

    The interactive effects between interdependent and independent self-construal on family cohesion and mental distress were examined. Survey responses from 153 Asian American high school students supported the hypothesized moderation of interdependence by independence on family cohesion, which was found to further mediate the relationship between self-construal and mental distress. Specifically, interdependence was positively associated with family cohesion when independence was high and negatively associated with family cohesion when independence was low. Accounting for the mediator effects of family cohesion, mental distress was positively associated with interdependence and more so for those low on independence than those high on independence. The benefits of biculturalism and research implications for the bidimensional conceptualization of self-construal for ethnic minority populations are discussed. PMID:17500602

  11. Left Atrium by Echocardiography in Clinical Practice: From Conventional Methods to New Echocardiographic Techniques

    PubMed Central

    Caso, Pio; D'Andrea, Antonello; Di Salvo, Giovanni; Arenga, Fortunato; Coppola, Maria Gabriella; Sellitto, Vincenzo; Macrino, Maria; Calabrò, Raffaele

    2014-01-01

    Although often referred to as “the forgotten chamber”, compared with left ventricle (LV), especially in the past years, the left atrium (LA) plays a critical role in the clinical expression and prognosis of patients with heart and cerebrovascular disease, as demonstrated by several studies. Echocardiographers initially focused on early detection of atrial geometrical abnormalities through monodimensional atrial diameter quantification and then bidimensional (2D) areas and volume estimation. Now, together with conventional echocardiographic parameters, new echocardiographic techniques, such as strain Doppler, 2D speckle tracking and three-dimensional (3D) echocardiography, allow assessing early LA dysfunction and they all play a fundamental role to detect early functional remodelling before anatomical alterations occur. LA dysfunction and its important prognostic implications may be detected sooner by LA strain than by volumetric measurements. PMID:25009828

  12. Code System to Simulate 3D Tracer Dispersion in Atmosphere.

    Energy Science and Technology Software Center (ESTSC)

    2002-01-25

    Version 00 SHREDI is a shielding code system which executes removal-diffusion computations for bi-dimensional shields in r-z or x-y geometries. It may also deal with monodimensional problems (infinitely high cylinders or slabs). MESYST can simulate 3D tracer dispersion in the atmosphere. Three programs are part of this system: CRE_TOPO prepares the terrain data for MESYST. NOABL calculates three-dimensional free divergence windfields over complex terrain. PAS computes tracer concentrations and depositions on a given domain. Themore » purpose of this work is to develop a reliable simulation tool for pollutant atmospheric dispersion, which gives a realistic approach and allows one to compute the pollutant concentrations over complex terrains with good accuracy. The factional brownian model, which furnishes more accurate concentration values, is introduced to calculate pollutant atmospheric dispersion. The model was validated on SIESTA international experiments.« less

  13. Heterogeneity of compulsive buyers based on impulsivity and compulsivity dimensions: a latent profile analytic approach.

    PubMed

    Yi, Sunghwan

    2013-07-30

    Despite the recognition that compulsive buyers are not one homogenous group, there is a dearth of theory-guided empirical investigation. Furthermore, although compulsivity and impulsivity are used as major psychiatric criteria for diagnosing compulsive buyers, these dimensions have rarely been considered in assessing the heterogeneity issue. We fill this gap by applying the motivation shift model of addiction to compulsive buying and empirically assessing the heterogeneity issue in the bi-dimensional space represented by the buying impulsivity and compulsivity dimensions. These hypotheses were tested with latent profile analysis based on survey data (N=445). Consistent with the hypothesis, we identified the cluster of buyers with high buying compulsivity and impulsivity ("compulsive-impulsive buyers"), the cluster of buyers with low buying compulsivity and high impulsivity ("impulsive excessive buyers"), and the cluster of ordinary buyers. Furthermore, it was found that disparate clusters of buyers exhibit unique dispositional tendencies. Theoretical contributions and policy implications of the findings are discussed as well. PMID:23083915

  14. Environmental effect on essential oil composition of Aloysia citriodora from Corrientes (Argentina).

    PubMed

    Ricciardi, Gabriela; Torres, Ana Maria; Bubenik, Ana Laura; Ricciardi, Armando; Lorenzo, Daniel; Dellacassa, Eduardo

    2011-11-01

    Lemon verbena (Aloysia citriodora Palau) is indigenous to South America and was introduced into Europe. It is cultivated mainly due to the lemon-like aroma emitted from its leaves, which are utilized for the preparation of herbal tea reputed to have antispasmodic, antipyretic, sedative and digestive properties. In this work we introduce the enantiomeric distribution of sabinene and limonene by bidimensional gas chromatography (chiral GC-GC) as a genuine quantitative parameter in order to improve the knowledge so far available on A. citriodora oil. Multivariate analysis afforded information on the similarities and differences of wild and cultivated A. citriodora populations during different seasons in the same environmental conditions. The results indicated that it was possible to discard the environmental and seasonal effect on the chemical composition of A. citriodora for wild and cultivated materials belonging to the same genetic origin. PMID:22224294

  15. Hybrid methods for witnessing entanglement in a microscopic-macroscopic system

    SciTech Connect

    Spagnolo, Nicolo; Vitelli, Chiara; Paternostro, Mauro; De Martini, Francesco; Sciarrino, Fabio

    2011-09-15

    We propose a hybrid approach to the experimental assessment of the genuine quantum features of a general system consisting of microscopic and macroscopic parts. We infer entanglement by combining dichotomic measurements on a bidimensional system and phase-space inference through the Wigner distribution associated with the macroscopic component of the state. As a benchmark, we investigate the feasibility of our proposal in a bipartite-entangled state composed of a single-photon and a multiphoton field. Our analysis shows that, under ideal conditions, maximal violation of a Clauser-Horne-Shimony-Holt-based inequality is achievable regardless of the number of photons in the macroscopic part of the state. The difficulty in observing entanglement when losses and detection inefficiency are included can be overcome by using a hybrid entanglement witness that allows efficient correction for losses in the few-photon regime.

  16. Stereotyping by Omission: Eliminate the Negative, Accentuate the Positive

    PubMed Central

    Bergsieker, Hilary B.; Leslie, Lisa M.; Constantine, Vanessa S.; Fiske, Susan T.

    2014-01-01

    Communicators, motivated by strategic self-presentation, selectively underreport negative content in describing their impressions of individuals and stereotypes of groups, particularly for targets whom they view ambivalently with respect to warmth and competence. Communicators avoid overtly inaccurate descriptions, preferring to omit negative information and emphasize positive information about mixed individual targets (Study 1). With more public audiences, communicators increasingly prefer negativity omission to complete accuracy (Study 2), a process driven by self-presentation concerns (Study 3), and moderated by bidimensional ambivalence. Similarly, in an extension of the Princeton Trilogy studies, reported stereotypes of ethnic and national outgroups systematically omitted negative dimensions over 75 years—as anti-prejudice norms intensified—while neutral and positive stereotype dimensions remained constant (Study 4). Multiple assessment methods confirm this stereotyping-by-omission phenomenon (Study 5). Implications of negativity omission for innuendo and stereotype stagnation are discussed. PMID:22448889

  17. Estimation of Thickness and Cadmium Composition Distributions in HgCdTe Focal Plane Arrays

    NASA Astrophysics Data System (ADS)

    Mouzali, S.; Lefebvre, S.; Rommeluère, S.; Ferrec, Y.; Primot, J.

    2016-09-01

    Mercury cadmium telluride (HgCdTe) is one of the most commonly used material systems for infrared detection. The performance of infrared focal-plane arrays (IRFPAs) based on this material is limited by several noise sources. In this paper, we focus on the fixed pattern noise, which is related to disparities between the spectral responses of pixels. In our previous work, we showed that spectral nonuniformities in a HgCdTe IRFPA were caused by inhomogeneities of thickness and cadmium composition in the HgCdTe layer, using an optical description of the pixel structure. We propose to use this bidimensional dependence combined with experimental spectral responses to estimate disparities of thickness and cadmium composition in a specific HgCdTe-based IRFPA. The estimation methods and the resulting maps are presented, highlighting the accuracy of this nondestructive method.

  18. [Isolation of Mycobacterium avium-intracellulare from a hepatic biopsy].

    PubMed

    Ruiz, Aroldo; Mederos, Lilian; Capó, Virginia

    2002-01-01

    A 64 years-old patient, who was a farmer suffering from chronic fever for two years, loss of weight and acute asthenia, was studied. He was admitted to "Pedro Kourí" Tropical Medicine Institute where the studies were conducted and revealed a globular sedimentation rate of 116 mm in 2 hours, and anemia of 9,8g% hemoglobin. The laparoscopic study indicated hepatic granulomatosis that was confirmed by hepatic biopsy in which a sample was taken from the liver to be microbiologically and cytologically examined. By microbiological methods, a non-pigmented slowly-growing strain was isolated, which was classified by conventional diagnostic techniques for the non-tuberculous mycobacteria classification and the alternative diagnosing technique known as bidimensional thin layer chromatography to confirm the previous classification and set the mycolic acid patterns. The isolated strain belonged to group III of Rynyon and was identified as Mycobacterium avium-intracellulare. PMID:15849945

  19. Analysis of off-state leakage mechanisms in GaN-based MIS-HEMTs: Experimental data and numerical simulation

    NASA Astrophysics Data System (ADS)

    Marino, F. A.; Bisi, D.; Meneghini, M.; Verzellesi, G.; Zanoni, E.; Van Hove, M.; You, S.; Decoutere, S.; Marcon, D.; Stoffels, S.; Ronchi, N.; Meneghesso, G.

    2015-11-01

    This paper presents an extensive analysis of the off-state conduction mechanisms in AlGaN/GaN Meta-Insulator-Semiconductor (MIS) transistors. Based on combined bi-dimensional numerical simulation and experimental measurements, we demonstrate the following relevant results: (i) under off-state bias conditions, the drain current can show a significant increase when the drain bias is swept up to 600 V; (ii) several mechanisms can be responsible for off-state current conduction, including band-to-band tunneling and impact ionization; (iii) two-dimensional numerical simulations indicate that band-to-band tunneling plays a major role, while impact ionization does not significantly contribute to the overall leakage. Temperature-dependent I-V measurements were also carried out to identify the origin of the vertical drain-bulk leakage.

  20. Surface treatment for the atomic layer deposition of HfO{sub 2} on silicon

    SciTech Connect

    Damlencourt, J-F.; Renault, O.; Martin, F.; Semeria, M-N.; Billon, T; Bedu, F.

    2005-04-04

    The atomic layer deposition (ALD) of HfO{sub 2} on silicon with a Cl{sub 2} surface treatment is investigated by physicochemical and electrical techniques. The specificity of this treatment is to create, on a HF-dipped silicon surface, the nucleation sites necessary for the ALD growth. The growth rates obtained by spectroscopic ellipsometry and total x-ray fluorescence spectroscopy indicate that the nucleation sites (i.e., the -OH groups), which are necessary to perform some bidimensional ALD growth, are generated during this surface treatment. After deposition of thin HfO{sub 2} layers (from a few monolayers up to 8.7 nm), a very thin parasitic SiO{sub x} layer, underneath 1 monolayer of Hf silicate, is observed by x-ray photoelectron spectroscopy. Nevertheless, an equivalent oxide thickness of 1.1 nm is obtained with an as-deposited 3.7 nm thick HfO{sub 2} layer.

  1. Neuromorphic Silicon Neuron Circuits

    PubMed Central

    Indiveri, Giacomo; Linares-Barranco, Bernabé; Hamilton, Tara Julia; van Schaik, André; Etienne-Cummings, Ralph; Delbruck, Tobi; Liu, Shih-Chii; Dudek, Piotr; Häfliger, Philipp; Renaud, Sylvie; Schemmel, Johannes; Cauwenberghs, Gert; Arthur, John; Hynna, Kai; Folowosele, Fopefolu; Saighi, Sylvain; Serrano-Gotarredona, Teresa; Wijekoon, Jayawan; Wang, Yingxue; Boahen, Kwabena

    2011-01-01

    Hardware implementations of spiking neurons can be extremely useful for a large variety of applications, ranging from high-speed modeling of large-scale neural systems to real-time behaving systems, to bidirectional brain–machine interfaces. The specific circuit solutions used to implement silicon neurons depend on the application requirements. In this paper we describe the most common building blocks and techniques used to implement these circuits, and present an overview of a wide range of neuromorphic silicon neurons, which implement different computational models, ranging from biophysically realistic and conductance-based Hodgkin–Huxley models to bi-dimensional generalized adaptive integrate and fire models. We compare the different design methodologies used for each silicon neuron design described, and demonstrate their features with experimental results, measured from a wide range of fabricated VLSI chips. PMID:21747754

  2. An experimental study of the "faster-is-slower" effect using mice under panic

    NASA Astrophysics Data System (ADS)

    Lin, Peng; Ma, Jian; Liu, Tianyang; Ran, Tong; Si, Youliang; Li, Tao

    2016-06-01

    A number of crowd accidents in last decades have attracted the interests of scientists in the study of self-organized behavior of crowd under extreme conditions. The faster-is-slower effect is one of the most referenced behaviors in pedestrian dynamics. However, this behavior has not been experimentally verified yet. A series of experiments with mice under panic were conducted in a bi-dimensional space. The mice were trained to be familiar with the way of escape. A varying number of joss sticks were used to produce different levels of stimulus to drive the mice to escape. The evacuation process was video-recorded for further analysis. The experiment found that the escape times significantly increased with the levels of stimulus due to the stronger competition of selfish mice in panic condition. The faster-is-slower effect was experimentally verified. The probability distributions of time intervals showed a power law and the burst sizes exhibited an exponential behavior.

  3. Time-cumulated visible and infrared radiance histograms used as descriptors of surface and cloud variations

    NASA Technical Reports Server (NTRS)

    Seze, Genevieve; Rossow, William B.

    1991-01-01

    The spatial and temporal stability of the distributions of satellite-measured visible and infrared radiances, caused by variations in clouds and surfaces, are investigated using bidimensional and monodimensional histograms and time-composite images. Similar analysis of the histograms of the original and time-composite images provides separation of the contributions of the space and time variations to the total variations. The variability of both the surfaces and clouds is found to be larger at scales much larger than the minimum resolved by satellite imagery. This study shows that the shapes of these histograms are distinctive characteristics of the different climate regimes and that particular attributes of these histograms can be related to several general, though not universal, properties of clouds and surface variations at regional and synoptic scales. There are also significant exceptions to these relationships in particular climate regimes. The characteristics of these radiance histograms provide a stable well defined descriptor of the cloud and surface properties.

  4. Growth Laws and Self-Similar Growth Regimes of Coarsening Two-Dimensional Foams: Transition from Dry to Wet Limits

    NASA Astrophysics Data System (ADS)

    Fortuna, Ismael; Thomas, Gilberto L.; de Almeida, Rita M. C.; Graner, François

    2012-06-01

    We study the topology and geometry of two-dimensional coarsening foam with an arbitrary liquid fraction. To interpolate between the dry limit described by von Neumann’s law and the wet limit described by Marqusee’s equation, the relevant bubble characteristics are the Plateau border radius and a new variable: the effective number of sides. We propose an equation for the individual bubble growth rate as the weighted sum of the growth through bubble-bubble interfaces and through bubble-Plateau border interfaces. The resulting prediction is successfully tested, without an adjustable parameter, using extensive bidimensional Potts model simulations. The simulations also show that a self-similar growth regime is observed at any liquid fraction, and they also determine how the average size growth exponent, side number distribution, and relative size distribution interpolate between the extreme limits. Applications include concentrated emulsions, grains in polycrystals, and other domains with coarsening that is driven by curvature.

  5. Reduced ablative Rayleigh-Taylor growth measurements in indirectly driven laminated foils

    SciTech Connect

    Huser, G.; Casner, A.; Masse, L.; Liberatore, S.; Galmiche, D.; Jacquet, L.; Theobald, M.

    2011-01-15

    Indirectly driven, ablative Rayleigh-Taylor instability growth measurements in Ge-doped plastic foils were studied using face-on and side-on x-ray radiography. Laminated samples consisting of alternating layers of Ge-doped and undoped plastic and homogeneous Ge-doped foils were considered. We show for the first time that hydrodynamics do not depend upon structuration of the samples and that stabilization occurs in the case of laminated samples. All data were found to be in good agreement with bi-dimensional hydrosimulations based on theoretical and numerical predictions published earlier [L. Masse, Phys. Rev. Lett. 98, 245001 (2007)], encouraging new designs using laminated structures for ignition capsules.

  6. Analysis of transit time spread on FBK silicon photomultipliers

    NASA Astrophysics Data System (ADS)

    Acerbi, F.; Gola, A.; Ferri, A.; Zorzi, N.; Paternoster, G.; Piemonte, C.

    2015-07-01

    In this paper we studied one of the aspects potentially limiting the single-photon time-resolution (SPTR) of the silicon photomultiplier (SiPM): the transit time spread (TTS). We illuminated the SiPM in different positions with a fast-pulsed laser collimated to a circular spot of 0.2 mm-diameter and acquired bi-dimensional maps of the avalanche-signal arrival time of RGB and RGB-HD SiPMs, produced at FBK. We studied the effect of both the number of bonding wires connecting the device to the package and the layout of the top-metal connection (on the device). We found that the TTS does not simply depend on the trace length between the cell and the bonding pad and it could vary in the range between tens of picoseconds (with 3 bonding connections) to more than one hundred of picoseconds (with one connection).

  7. Revealing the Structure of a Granular Medium through Ballistic Sound Propagation

    NASA Astrophysics Data System (ADS)

    Lherminier, S.; Planet, R.; Simon, G.; Vanel, L.; Ramos, O.

    2014-08-01

    We study the propagation of sound through a bidimensional granular medium consisting of photoelastic disks, which are packed into different crystalline and disordered structures. Acoustic sensors placed at the boundaries of the system capture the acoustic signal produced by a local and well-controlled mechanical excitation. By compressing the system, we find that the speed of the ballistic part of the acoustic wave behaves as a power law of the applied force with both exponent and prefactor sensitive to the internal geometry of the contact network. This information, which we are able to link to the force-deformation relation of single grains under different contact geometries, provides enough information to reveal the structure of the granular medium.

  8. Rise of a Brazil nut: A transition line

    NASA Astrophysics Data System (ADS)

    Godoy, Sergio; Risso, Dino; Soto, Rodrigo; Cordero, Patricio

    2008-09-01

    Using molecular dynamics we study the behavior of a large particle immersed in a bed of smaller ones. The system is bidimensional, consisting of many rough inelastic hard disks of equal size plus a larger one: the intruder. All possible parameters of the system are kept fixed except for two dimensionless parameters determining the frequency and amplitude of the vibrating base. A systematic exploration of this parameter space leads to determining a transition line separating a zone in which the Brazil nut effect is observed and one in which it is not. The results strongly suggest that, in the region of the parameter space in which the study is made, there is a minimum amplitude and a maximum frequency for the Brazil nut effect to take place. These results compare well with isolated results from other authors.

  9. Observation of a phononic Mollow triplet in a multimode hybrid spin-nanomechanical system

    NASA Astrophysics Data System (ADS)

    Pigeau, B.; Rohr, S.; Mercier de Lépinay, L.; Gloppe, A.; Jacques, V.; Arcizet, O.

    2015-10-01

    Reminiscent of the bound character of a qubit's dynamics confined on the Bloch sphere, the observation of a Mollow triplet in the resonantly driven qubit fluorescence spectrum represents one of the founding signatures of quantum electrodynamics. Here we report on its observation in a hybrid spin-nanomechanical system, where a nitrogen-vacancy spin qubit is magnetically coupled to the vibrations of a silicon carbide nanowire. A resonant microwave field turns the originally parametric hybrid interaction into a resonant process, where acoustic phonons are now able to induce transitions between the dressed qubit states, leading to synchronized spin-oscillator dynamics. We further explore the vectorial character of the hybrid coupling to the bidimensional deformations of the nanowire. The demonstrated microwave assisted synchronization of the spin-oscillator dynamics opens novel perspectives for the exploration of spin-dependent forces, the key ingredient for quantum state transfer.

  10. First dose-map measured with a polycrystalline diamond 2D dosimeter under an intensity modulated radiotherapy beam

    NASA Astrophysics Data System (ADS)

    Scaringella, M.; Zani, M.; Baldi, A.; Bucciolini, M.; Pace, E.; de Sio, A.; Talamonti, C.; Bruzzi, M.

    2015-10-01

    A prototype of bidimensional dosimeter made on a 2.5×2.5 cm2 active area polycrystalline Chemical Vapour Deposited (pCVD) diamond film, equipped with a matrix of 12×12 contacts connected to the read-out electronics, has been used to evaluate a map of dose under Intensity Modulated Radiation Therapy (IMRT) fields for a possible application in pre-treatment verifications of cancer treatments. Tests have been performed under a 6-10 MVRX beams with IMRT fields for prostate and breast cancer. Measurements have been taken by measuring the 144 pixels in different positions, obtained by shifting the device along the x/y axes to span a total map of 14.4×10 cm2. Results show that absorbed doses measured by our pCVD diamond device are consistent with those calculated by the Treatment Planning System (TPS).

  11. Dynamical analysis of fluid lines coupled to mechanical systems taking into account fluid frequency-dependent damping and non-conventional constitutive models: part 1 - Modeling fluid lines

    NASA Astrophysics Data System (ADS)

    Catania, Giuseppe; Sorrentino, Silvio

    2015-01-01

    The design of hydraulic transmission systems for control and actuation requires accurate knowledge of their dynamic response: some standard techniques are known to obtain a consistent dynamic model of a fluid line, including the contribution of inertia, compressibility and friction. In this paper an efficient procedure is developed for simulating the dynamic response of a fluid line in both the frequency and time domains, focusing the attention on the modal analysis of a discretized model, in view of coupling with mechanical systems. A bi-dimensional approach is adopted, and the laminar flow frequency-dependent friction is modeled using non-integer order differential laws, which may improve the accuracy of the simulated responses in comparison with more traditional Newtonian models.

  12. Dynamical analysis of fluid lines coupled to mechanical systems taking into account fluid frequency-dependent damping and non-conventional constitutive models: Part 2 - Coupling with mechanical systems

    NASA Astrophysics Data System (ADS)

    Catania, Giuseppe; Sorrentino, Silvio

    2015-01-01

    The design of hydraulic transmission systems for control and actuation requires accurate knowledge of their dynamic response: some standard techniques are known to obtain a consistent dynamic model of a fluid line, including the contribution of inertia, compressibility and friction. In this study an efficient procedure is developed for simulating the dynamic response of a fluid line coupled with mechanical systems, in both the frequency and time domains. A bi-dimensional approach is adopted for the fluid line, and the laminar flow frequency-dependent friction is modeled using non-integer order differential laws, which may improve the accuracy in comparison with more traditional Newtonian models. The coupling problem with mechanical systems is studied by means of both continuous models of the fluid line (yielding frequency response functions in exact analytical form), and discretized models of the fluid line (to express time response functions in approximate analytical form), focusing on the damping properties of the resulting vibrating systems.

  13. Testing quantum contextuality of continuous-variable states

    SciTech Connect

    McKeown, Gerard; Paternostro, Mauro; Paris, Matteo G. A.

    2011-06-15

    We investigate the violation of noncontextuality by a class of continuous-variable states, including variations of entangled coherent states and a two-mode continuous superposition of coherent states. We generalize the Kochen-Specker (KS) inequality discussed by Cabello [A. Cabello, Phys. Rev. Lett. 101, 210401 (2008)] by using effective bidimensional observables implemented through physical operations acting on continuous-variable states, in a way similar to an approach to the falsification of Bell-Clauser-Horne-Shimony-Holt inequalities put forward recently. We test for state-independent violation of KS inequalities under variable degrees of state entanglement and mixedness. We then demonstrate theoretically the violation of a KS inequality for any two-mode state by using pseudospin observables and a generalized quasiprobability function.

  14. Pangolin v1.0, a conservative 2-D advection model towards large-scale parallel calculation

    NASA Astrophysics Data System (ADS)

    Praga, A.; Cariolle, D.; Giraud, L.

    2015-02-01

    To exploit the possibilities of parallel computers, we designed a large-scale bidimensional atmospheric advection model named Pangolin. As the basis for a future chemistry-transport model, a finite-volume approach for advection was chosen to ensure mass preservation and to ease parallelization. To overcome the pole restriction on time steps for a regular latitude-longitude grid, Pangolin uses a quasi-area-preserving reduced latitude-longitude grid. The features of the regular grid are exploited to reduce the memory footprint and enable effective parallel performances. In addition, a custom domain decomposition algorithm is presented. To assess the validity of the advection scheme, its results are compared with state-of-the-art models on algebraic test cases. Finally, parallel performances are shown in terms of strong scaling and confirm the efficient scalability up to a few hundred cores.

  15. Pangolin v1.0, a conservative 2-D transport model for large scale parallel calculation

    NASA Astrophysics Data System (ADS)

    Praga, A.; Cariolle, D.; Giraud, L.

    2014-07-01

    To exploit the possibilities of parallel computers, we designed a large-scale bidimensional atmospheric transport model named Pangolin. As the basis for a future chemistry-transport model, a finite-volume approach was chosen both for mass preservation and to ease parallelization. To overcome the pole restriction on time-steps for a regular latitude-longitude grid, Pangolin uses a quasi-area-preserving reduced latitude-longitude grid. The features of the regular grid are exploited to improve parallel performances and a custom domain decomposition algorithm is presented. To assess the validity of the transport scheme, its results are compared with state-of-the-art models on analytical test cases. Finally, parallel performances are shown in terms of strong scaling and confirm the efficient scalability up to a few hundred of cores.

  16. Generation and transfer of polarized radiation in the solar atmosphere: Physical mechanisms and magnetic-field diagnostics

    NASA Technical Reports Server (NTRS)

    Deglinnocenti, E. L.

    1985-01-01

    The main physical mechanisms responsible for the generation and transfer of polarized radiation in the solar atmosphere can be classified in a suitable bidimensional diagram with an indicator of the magnetic field strength on its vertical axis and an indicator of the radiation field anisotropy on its horizontal axis. The various polarimetric observations performed on solar spectral lines are interpreted with different theoretical schemes according to their classification in the diagram and to the optical depths involved. These theoretical schemes, and the associated diagnostic tools for inferring the magnetic field vector from observations are reviewed. In particular, the role of magneto-optical effects in determining the direction of the observed linear polarization in active regions is discussed in some detail.

  17. Observation of a phononic Mollow triplet in a multimode hybrid spin-nanomechanical system.

    PubMed

    Pigeau, B; Rohr, S; Mercier de Lépinay, L; Gloppe, A; Jacques, V; Arcizet, O

    2015-01-01

    Reminiscent of the bound character of a qubit's dynamics confined on the Bloch sphere, the observation of a Mollow triplet in the resonantly driven qubit fluorescence spectrum represents one of the founding signatures of quantum electrodynamics. Here we report on its observation in a hybrid spin-nanomechanical system, where a nitrogen-vacancy spin qubit is magnetically coupled to the vibrations of a silicon carbide nanowire. A resonant microwave field turns the originally parametric hybrid interaction into a resonant process, where acoustic phonons are now able to induce transitions between the dressed qubit states, leading to synchronized spin-oscillator dynamics. We further explore the vectorial character of the hybrid coupling to the bidimensional deformations of the nanowire. The demonstrated microwave assisted synchronization of the spin-oscillator dynamics opens novel perspectives for the exploration of spin-dependent forces, the key ingredient for quantum state transfer. PMID:26477639

  18. Antifungal and cytotoxic activity of withanolides from Acnistus arborescens.

    PubMed

    Roumy, Vincent; Biabiany, Murielle; Hennebelle, Thierry; Aliouat, El Moukhtar; Pottier, Muriel; Joseph, Henry; Joha, Sami; Quesnel, Bruno; Alkhatib, Racha; Sahpaz, Sevser; Bailleul, François

    2010-07-23

    Three compounds were isolated from Acnistus arborescens, a tree commonly used in South and Central America in traditional medicine against several infectious diseases, some of which are caused by fungi. Bioassay-guided fractionation of a MeOH extract of leaves, based on its anti-Pneumocystis carinii activity, led to the isolation of compounds 1-3. Mono- and bidimensional NMR analyses enabled identification of two new withanolides, (20R,22R)-5beta,6beta-epoxy-4beta,12beta,20-trihydroxy-1-oxowith-2-en-24-enolide (1) and (20R,22R)-16beta-acetoxy-3beta,4beta;5beta,6beta-diepoxy-12beta,20-dihydroxy-1-oxowith-24-enolide (2), and withanolide D (3). Antifungal activity on 13 fungi responsible for human infections (five dermatophytes, one nondermatophyte mold, six yeasts, and Pneumocystis carinii) was examined. Cytotoxicity of these compounds was also evaluated in vitro. PMID:20590148

  19. Consciousness: a neurological perspective.

    PubMed

    Cavanna, Andrea E; Shah, Sachin; Eddy, Clare M; Williams, Adrian; Rickards, Hugh

    2011-01-01

    Consciousness is a state so essentially entwined with human experience, yet so difficult to conceptually define and measure. In this article, we explore how a bidimensional model of consciousness involving both level of arousal and subjective awareness of the contents of consciousness can be used to differentiate a range of healthy and altered conscious states. These include the different sleep stages of healthy individuals and the altered states of consciousness associated with neurological conditions such as epilepsy, vegetative state and coma. In particular, we discuss how arousal and awareness are positively correlated in normal physiological states with the exception of REM sleep, while a disturbance in this relationship is characteristic of vegetative state, minimally conscious state, complex partial seizures and sleepwalking. PMID:21447904

  20. From scientific discovery to health outcomes: A synergistic model of doctoral nursing education.

    PubMed

    Michael, Melanie J; Clochesy, John M

    2016-05-01

    Across the globe, health system leaders and stakeholder are calling for system-level reforms in education, research, and practice to accelerate the uptake and application of new knowledge in practice and to improve health care delivery and health outcomes. An evolving bi-dimensional research-practice focused model of doctoral nursing education in the U.S. is creating unprecedented opportunities for collaborative translational and investigative efforts for nurse researchers and practitioners. The nursing academy must commit to a shared goal of preparing future generations of nurse scientists and practitioners with the capacity and motivation to work together to accelerate the translation of evidence into practice in order to place nursing at the forefront of health system improvement efforts and advance the profession. PMID:27125154

  1. Spontaneous chiral resolution in two-dimensional systems of patchy particles.

    PubMed

    Martínez-González, J A; Chapela, G A; Quintana-H, J

    2014-05-21

    Short ranged potentials and their anisotropy produce spontaneous chiral resolution in a two dimensional model of patchy particles introduced in this paper. This model could represent an equimolar binary mixture (racemic mixture) of two kinds of chiral molecules (enantiomers) adsorbed to a bi-dimensional domain where only lateral short ranged interactions are present. Most racemic mixtures undergo chiral resolution due to their spatial anisotropy, the combined effect of long range forces and the thermodynamic conditions. The patchy particles are modeled as a hard disk and four different bonding sites located to produce chirality. Phase behavior and structural properties are analysed using Discontinuous Molecular Dynamics in the canonical ensemble. When the four patchy particles are separated by the angles {60°, 120°, 60°, 120°}, spontaneous chiral resolution is produced, given by the formation of homochiral clusters, if started from the corresponding racemic mixture. Gel behavior is also obtained in all the systems for low temperatures and low densities. PMID:24852548

  2. Spontaneous chiral resolution in two-dimensional systems of patchy particles

    SciTech Connect

    Martínez-González, J. A.; Chapela, G. A.; Quintana-H, J.

    2014-05-21

    Short ranged potentials and their anisotropy produce spontaneous chiral resolution in a two dimensional model of patchy particles introduced in this paper. This model could represent an equimolar binary mixture (racemic mixture) of two kinds of chiral molecules (enantiomers) adsorbed to a bi-dimensional domain where only lateral short ranged interactions are present. Most racemic mixtures undergo chiral resolution due to their spatial anisotropy, the combined effect of long range forces and the thermodynamic conditions. The patchy particles are modeled as a hard disk and four different bonding sites located to produce chirality. Phase behavior and structural properties are analysed using Discontinuous Molecular Dynamics in the canonical ensemble. When the four patchy particles are separated by the angles (60°, 120°, 60°, 120°), spontaneous chiral resolution is produced, given by the formation of homochiral clusters, if started from the corresponding racemic mixture. Gel behavior is also obtained in all the systems for low temperatures and low densities.

  3. A Lattice Boltzmann Model for Oscillating Reaction-Diffusion

    NASA Astrophysics Data System (ADS)

    Rodríguez-Romo, Suemi; Ibañez-Orozco, Oscar; Sosa-Herrera, Antonio

    2016-07-01

    A computational algorithm based on the lattice Boltzmann method (LBM) is proposed to model reaction-diffusion systems. In this paper, we focus on how nonlinear chemical oscillators like Belousov-Zhabotinsky (BZ) and the chlorite-iodide-malonic acid (CIMA) reactions can be modeled by LBM and provide with new insight into the nature and applications of oscillating reactions. We use Gaussian pulse initial concentrations of sulfuric acid in different places of a bidimensional reactor and nondiffusive boundary walls. We clearly show how these systems evolve to a chaotic attractor and produce specific pattern images that are portrayed in the reactions trajectory to the corresponding chaotic attractor and can be used in robotic control.

  4. Estimation of Thickness and Cadmium Composition Distributions in HgCdTe Focal Plane Arrays

    NASA Astrophysics Data System (ADS)

    Mouzali, S.; Lefebvre, S.; Rommeluère, S.; Ferrec, Y.; Primot, J.

    2016-05-01

    Mercury cadmium telluride (HgCdTe) is one of the most commonly used material systems for infrared detection. The performance of infrared focal-plane arrays (IRFPAs) based on this material is limited by several noise sources. In this paper, we focus on the fixed pattern noise, which is related to disparities between the spectral responses of pixels. In our previous work, we showed that spectral nonuniformities in a HgCdTe IRFPA were caused by inhomogeneities of thickness and cadmium composition in the HgCdTe layer, using an optical description of the pixel structure. We propose to use this bidimensional dependence combined with experimental spectral responses to estimate disparities of thickness and cadmium composition in a specific HgCdTe-based IRFPA. The estimation methods and the resulting maps are presented, highlighting the accuracy of this nondestructive method.

  5. LIDAR Data Resolution Versus Hydro-Morphological Models for Flood Risk Assessment

    NASA Astrophysics Data System (ADS)

    Avanzi, A.; Frank, E.; Righetto, M.; Fattorelli, S.

    2013-01-01

    Uncertainties in topographic data have a significant influence on hydro-morphological and hydraulic predictions and therefore on flood risk assessment. In this work, the effects of topographic data resolution on the results of hydro-morphologic and hydraulic simulations are analysed using respectively the morphological bi-dimensional curvilinear model MIKE 21C and mono-bidimensional SOBEK. The studies have been carried out in the Torre river, located in Northern Italy. The evaluations on hydro-morphological and hydraulic risk require accurate spatial information for the area of interest. In order to characterize the river morphology, mainly for large areas, the availability of high resolution topography derived by airborne laser scanner represents an effective tool. Nowadays LiDAR (Light Detection And Ranging) DTM covering large areas are readily available for public authorities, and there is a greater and more widespread interest in the application of such information for the development of automated methods aimed at solving geomorphological and hydrological problems. For the models analysed, high-resolution LiDAR data were used to create the basic topographic information. An additional source for the topography of the Torre river has been provided by river cross-section data. Digital elevation models at different resolution have been created to test the effects of different grid cell sizes on the simulations. The impact of topographic information on hydraulic and morphological model results was evaluated for the area through a comparison of results. Additionally, morphologic variations and position of erosional and depositional zones along the watercourse and variations in flood extent and dynamics have been investigated. The obtained results emphasise the importance of quality of input information for reliable results of hydraulic and sediment transport models. Criteria for selecting the optimal DTM resolution are suggested, based on the quality of available

  6. Hierarchical structures of correlations networks among Turkey’s exports and imports by currencies

    NASA Astrophysics Data System (ADS)

    Kocakaplan, Yusuf; Deviren, Bayram; Keskin, Mustafa

    2012-12-01

    We have examined the hierarchical structures of correlations networks among Turkey’s exports and imports by currencies for the 1996-2010 periods, using the concept of a minimal spanning tree (MST) and hierarchical tree (HT) which depend on the concept of ultrametricity. These trees are useful tools for understanding and detecting the global structure, taxonomy and hierarchy in financial markets. We derived a hierarchical organization and build the MSTs and HTs during the 1996-2001 and 2002-2010 periods. The reason for studying two different sub-periods, namely 1996-2001 and 2002-2010, is that the Euro (EUR) came into use in 2001, and some countries have made their exports and imports with Turkey via the EUR since 2002, and in order to test various time-windows and observe temporal evolution. We have carried out bootstrap analysis to associate a value of the statistical reliability to the links of the MSTs and HTs. We have also used the average linkage cluster analysis (ALCA) to observe the cluster structure more clearly. Moreover, we have obtained the bidimensional minimal spanning tree (BMST) due to economic trade being a bidimensional problem. From the structural topologies of these trees, we have identified different clusters of currencies according to their proximity and economic ties. Our results show that some currencies are more important within the network, due to a tighter connection with other currencies. We have also found that the obtained currencies play a key role for Turkey’s exports and imports and have important implications for the design of portfolio and investment strategies.

  7. A New Oxyborate in the Ternary Phase Diagrams Li 2O- Ln2O 3-B 2O 3: Li 2Ln5O 4(BO 3) 3 ( Ln=Yb, Lu): Crystal Structure of the Ytterbium Phase

    NASA Astrophysics Data System (ADS)

    Jubera, Veronique; Gravereau, Pierre; Chaminade, Jean-Pierre; Fouassier, Claude

    2001-01-01

    A new type of lithium rare earth oxyborate of formula Li2Ln5O4(BO3)3 (Ln=Yb, Lu) has been discovered in the ternary phase diagrams Li2O-Ln2O3-B2O3. Single crystals of Li2Yb5O4(BO3)3 were grown by the flux method. The structure of this oxyborate was solved from a data collection with a four circle automatic diffractometer and with MoKα radiation. The cell is monoclinic (space group P21/m, Z=2) with a=10.095(2) Å, b=3.519(2) Å, c=15.647(11) Å, β=105.45(3)°, V=535.7(5) Å-3. Refinement of 86 parameters using 3298 independent reflections having intensity I>2σ(I) led to R=0.037 (wR=0.091). The structure of Li2Yb5O4(BO3)3 is made up of a bidimensional framework of edge or corner-sharing YbO7 polyhedra parallel to the (10overline1) plane and connected by three-coordinated boron atoms and lithium ions. It can also be described as a bidimensional assembly of OYb4 tetrahedra, ((Yb10O8)14+)n, separated by borate groups and lithium coordination polyhedra forming ribbons, ((Li4B6O18)14-)n, along the b direction. The presence of oxygen atoms sharing only Yb polyhedra justifies the oxyborate label.

  8. Nonlinear absorption tuning by composition control in bimetallic plasmonic nanoprism arrays

    NASA Astrophysics Data System (ADS)

    Cesca, Tiziana; Michieli, Niccolò; Kalinic, Boris; Sánchez-Espinoza, Ana; Rattin, Marco; Russo, Valentina; Mattarello, Valentina; Scian, Carlo; Mazzoldi, Paolo; Mattei, Giovanni

    2015-07-01

    The nonlinear absorption properties of bidimensional arrays of Au-Ag bilayered nanoprisms have been investigated by z-scan measurements as a function of the bimetallic nanoprism composition. A tunable ps laser system was used to excite the ultrafast, electronic nonlinear response matching the laser wavelength with the quadrupolar surface plasmon resonances, in the visible range, of each nanoprism array. Due to the strong electromagnetic field confinement effects at the nanoprism tips, demonstrated by finite element method simulations, these nanosystems proved to have enhanced nonlinear optical properties. Moreover, a tunable changeover from reverse saturable absorption (RSA) to saturable absorption (SA) can be obtained by properly controlling the bimetallic composition of the nanoprisms, without modifying the overall morphology of the nanosystems. This capability makes these nanosystems extremely interesting for the realization of solid-state nanophotonic devices with enhanced ultrafast nonlinear optical properties.The nonlinear absorption properties of bidimensional arrays of Au-Ag bilayered nanoprisms have been investigated by z-scan measurements as a function of the bimetallic nanoprism composition. A tunable ps laser system was used to excite the ultrafast, electronic nonlinear response matching the laser wavelength with the quadrupolar surface plasmon resonances, in the visible range, of each nanoprism array. Due to the strong electromagnetic field confinement effects at the nanoprism tips, demonstrated by finite element method simulations, these nanosystems proved to have enhanced nonlinear optical properties. Moreover, a tunable changeover from reverse saturable absorption (RSA) to saturable absorption (SA) can be obtained by properly controlling the bimetallic composition of the nanoprisms, without modifying the overall morphology of the nanosystems. This capability makes these nanosystems extremely interesting for the realization of solid

  9. Equilibrium and stability properties of detonation waves in the hydrodynamic limit of a kinetic model

    NASA Astrophysics Data System (ADS)

    Marques, Wilson, Jr.; Jacinta Soares, Ana; Pandolfi Bianchi, Miriam; Kremer, Gilberto M.

    2015-06-01

    A shock wave structure problem, like the one which can be formulated for the planar detonation wave, is analyzed here for a binary mixture of ideal gases undergoing the symmetric reaction {{A}1}+{{A}1}\\rightleftharpoons {{A}2}+{{A}2}. The problem is studied at the hydrodynamic Euler limit of a kinetic model of the reactive Boltzmann equation. The chemical rate law is deduced in this frame with a second-order reaction rate, in a chemical regime such that the gas flow is not far away from the chemical equilibrium. The caloric and the thermal equations of state for the specific internal energy and temperature are employed to close the system of balance laws. With respect to other approaches known in the kinetic literature for detonation problems with a reversible reaction, this paper aims to improve some aspects of the wave solution. Within the mathematical analysis of the detonation model, the equation of the equilibrium Hugoniot curve of the final states is explicitly derived for the first time and used to define the correct location of the equilibrium Chapman-Jouguet point in the Hugoniot diagram. The parametric space is widened to investigate the response of the detonation solution to the activation energy of the chemical reaction. Finally, the mathematical formulation of the linear stability problem is given for the wave detonation structure via a normal-mode approach, when bidimensional disturbances perturb the steady solution. The stability equations with their boundary conditions and the radiation condition of the considered model are explicitly derived for small transversal deviations of the shock wave location. The paper shows how a second-order chemical kinetics description, derived at the microscopic level, and an analytic deduction of the equilibrium Hugoniot curve, lead to an accurate picture of the steady detonation with reversible reaction, as well as to a proper bidimensional linear stability analysis.

  10. An extended real-time flood impact forecasting system for the Chapare watershed in Bolivia

    NASA Astrophysics Data System (ADS)

    Rossi, Lauro; Gabellani, Simone; Masoero, Alessandro; Dolia, Daniele; Rudari, Roberto

    2016-04-01

    All over the world a lot of cities are located in flood-prone areas and million of people are exposed to inundation risk. To cope with that the social safety demands efficient civil protection structures able to reduce flood risk by issuing warnings. This task requires civil protection organisms to adopt systems able to support their activities in predicting floods and rainfall impacts. For this reason flood early warning systems, based on rainfall observations and predictions, has become very useful because they are able to provide in advance a quantitative evaluation of possible effects in term of discharge and peak flow. Traditionally those forecasting systems use hydrologic models coupled with meteorological models to forecast discharge in relevant river sections and are called hydro-meteorological chains. In order to have a better representation of the flood dynamics, these hydro-meteorological chains can be expanded to include bi-dimensional hydraulic models where the level exposure is high or flow singularities (e.g. junctions, deltas, etc.) require more accurate investigation. That information allows the generation of real-time inundation scenarios that can be used by civil protection and authorities to estimate impact on population and take counter-measures. The new real-time flood impact forecasting chain consists of a suite of hydrometeorological tools that combines meteorological models, a disaggregation tool and a fully distributed hydrological model and a bidimensional hydraulic model that produces inundation scenarios in the most exposed river segments of the flood plain and a scenario tool that allows the assessment of assets involved. The complete modelling chain has been implemented in the Chapare watershed in Bolivia and it is managed by the Dewetra platform, which since 2013 is used by the Civil Defense and National Meteorological service as the main national Early Warning supporting tool.

  11. Integral field spectroscopy and multi-wavelength imaging of the nearby spiral galaxy NGC 5668: a case for MEGARA

    NASA Astrophysics Data System (ADS)

    Marino, R. A.; Gil de Paz, A.; Castillo-Morales, A.; Muñoz-Mateos, J. C.; Sánchez, S. F.; Pérez-González, P. G.; Gallego, J.; Zamorano, J.; Alonso-Herrero, A.; Boissier, S.

    2013-05-01

    In order to improve our understanding of the mechanisms that drive the evolution of disk galaxies we analyze the full bi-dimensional spectral cube of the nearby spiral galaxy NGC 5668, which was obtained as a mosaic of 6 pointings, covering a total area of 2 × 3 arcmin^{2}, obtained with the PPAK Integral Field Unit at the Calar Alto (CAHA) observatory 3.5 m telescope. From these data we obtain the bidimensional spatial distribution maps of the attenuation of the ionized gas, and chemical abundances of oxygen. We find a mean ionized-gas attenuation of A_V˜1 mag, with the gas attenuation appearing larger than the continuum attenuation by a factor of 3. With respect to the oxygen abundance, we find that, while inwards of r ˜36''˜ 4.4kpc ˜ 0.36 ({D_{25}}/{2}) the derived O/H ratio follows the radial gradient typical of the disks of spiral galaxies, the abundance gradient beyond r˜36'' flattens out. The multi-wavelength surface brightness profiles of NGC 5668 are compared with those predicted by chemo-spectrophotometric evolutionary models of galaxy disks in the context of the inside-out scenario of disk formation. Both the deviations of the color profiles and the shape of the metallicity radial distribution indicate that a secondary mechanism, possibly gas transfer induced by the presence of a young bar, must have played a role in shaping the recent chemical and star formation histories of NGC5668 beyond what is predicted by the inside-out scenario. This study demonstrates the strength of the combination of IFU and multi-wavelength imaging data. With MEGARA, the future optical IFU & MOS for 10.4-m GTC we will fill the gap currently existing in astronomical instrumentation with high spectral resolution and large area coverage simultaneously addressing such fundamental issues in galactic structure and evolution.

  12. Separation and characterization of mares' milk alpha(s1)-, beta-, kappa-caseins, gamma-casein-like, and proteose peptone component 5-like peptides.

    PubMed

    Egito, A S; Miclo, L; López, C; Adam, A; Girardet, J M; Gaillard, J L

    2002-04-01

    The equine alpha(s1)- and beta-caseins (CN) were purified by chromatography on DEAE-cellulose and by reversed-phase HPLC. The alpha(s1)-, beta-, and kappa-CN were characterized either by monodimensional urea-PAGE or sodium dodecylsulfate (SDS)-PAGE or by bidimensional electrophoresis. Kappa-casein was characterized after electrophoresis by glycoprotein-specific staining. To identify alpha(s1)-CN without ambiguity, internal sequences were determined after trypsin or chymosin digestion of purified alpha(s1)-CN. These sequences, that could be estimated to correspond to 62% of the full protein, presented strong identities with regions of alpha(s1)-CN primary structures of other species. In particular, 51, 48, 43, and 40% identities were obtained with corresponding regions of sow, dromedary, cow, and human alpha(s1)-CN, respectively. On the other hand, trace amounts of equine gamma-CN-like and proteose peptone component 5-like peptides were found in the whole CN. They were identified by microsequencing and corresponded to beta-CN peptides generated by plasmin action on the whole CN. The equine alpha(s1), beta-, and kappa-CN were separated by bidimensional electrophoresis in numerous isoelectric variants with apparent isoelectric points distributed between pH 4.4 to 6.3, 4.4 to 5.9, and 3.5 to 5.5, respectively. The beta- and kappa-CN displayed a more acidic character in the mare than in the cow. PMID:12018413

  13. Élements d'introduction à l'invariance conforme

    NASA Astrophysics Data System (ADS)

    Grandati, Y.

    These notes constitute an elementary introduction to the concept of conformal invariance and its applications to the study of bidimensional critical phenomena. The aim is to give an access as pedestrian as possible to this vast subject. After a brief account of the general properties of conformal transformations in D dimensions, we study more specifically the case D = 2. The center of the discussion is then the consequences of the action of this symmetry group on bidimensional field theories, and in particular the links between the representations of the Virasoro algebra and the structure of the correlation functions of conformal field theories. Finally after showing how the Ising model reduces to a Majorana fermionic field theory, we see how the general formalism previously discussed can be applied to the Ising case at the critical point. Ce texte constitue une introduction élémentaire au concept d'invariance conforme et à ses applications dans l'étude des phénomènes critiques bidimensionnels. L'objectif est de fournir un accès aussi linéaire et pédagogique que possible aux idées de base de ce vaste sujet. Après une présentation sommaire des propriétés générales des transformations conformes en dimension quelconque, nous nous intéressons plus spécifiquement au cas de la dimension 2. Le coeur de la discussion porte alors sur les conséquences de l'action de ce groupe de symétrie sur les théories de champs bidimensionnelles et en particulier, sur les liens entre la théorie des représentations de l'algèbre de Virasoro et la structure des fonctions de corrélation des théories de champs invariantes conformes. Enfin, après avoir montré de quelle manière l'étude du modèle d'Ising peut être ramenée à celle d'une théorie de champs de fermions de Majorana, nous voyons comment le formalisme général discuté précédemment s'applique au cas de ce modèle au point critique.

  14. Concave gold nanocube assemblies as nanotraps for surface-enhanced Raman scattering-based detection of proteins

    NASA Astrophysics Data System (ADS)

    Matteini, Paolo; de Angelis, Marella; Ulivi, Lorenzo; Centi, Sonia; Pini, Roberto

    2015-02-01

    SERS detection of proteins is typically performed by using labeling agents with stable and high Raman scattering cross sections. This is a valuable approach for trace detection and quantification of a target protein but is unsuitable for inspecting its inherent structural and functional properties. On the other hand, direct SERS of proteins has been mainly devoted to the study of short peptides and aminoacid sequences or of prosthetic groups with intense Raman signals, which is of scarce interest for a thorough characterization of most proteins. Here we try to overcome these limitations by setting-up an effective platform for the structural SERS analysis of proteins. The platform consists of an extended bidimensional array of gold concave nanocubes (CNCs) supported on a PDMS film. CNCs are closely-packed through face-face and face-corner interactions generating a monolayered arrangement featuring well distributed nanoholes. Here the protein homogeneously experiences an E-field enhancement outward from the metal surfaces surrounding it, which causes a large number of vibrations to be contemporarily amplified. The proposed platform provides stable and detailed SERS spectra and confers rapidity and reproducibility to the analysis.SERS detection of proteins is typically performed by using labeling agents with stable and high Raman scattering cross sections. This is a valuable approach for trace detection and quantification of a target protein but is unsuitable for inspecting its inherent structural and functional properties. On the other hand, direct SERS of proteins has been mainly devoted to the study of short peptides and aminoacid sequences or of prosthetic groups with intense Raman signals, which is of scarce interest for a thorough characterization of most proteins. Here we try to overcome these limitations by setting-up an effective platform for the structural SERS analysis of proteins. The platform consists of an extended bidimensional array of gold concave

  15. Comparison of Existing Response Criteria in Patients with Hepatocellular Carcinoma Treated with Transarterial Chemoembolization Using a 3D Quantitative Approach

    PubMed Central

    Tacher, Vania; Lin, MingDe; Duran, Rafael; Yarmohammadi, Hooman; Lee, Howard; Chapiro, Julius; Chao, Michael; Wang, Zhijun; Frangakis, Constantine; Sohn, Jae Ho; Maltenfort, Mitchell Gil; Pawlik, Timothy; Geschwind, Jean-François

    2015-01-01

    Purpose To compare currently available non-three-dimensional methods (Response Evaluation Criteria in Solid Tumors [RECIST], European Association for Study of the Liver [EASL], modified RECIST [mRECIST[) with three-dimensional (3D) quantitative methods of the index tumor as early response markers in predicting patient survival after initial transcatheter arterial chemoembolization (TACE). Materials and Methods This was a retrospective single-institution HIPAA-compliant and institutional review board–approved study. From November 2001 to November 2008, 491 consecutive patients underwent intraarterial therapy for liver cancer with either conventional TACE or TACE with drug-eluting beads. A diagnosis of hepatocellular carcinoma (HCC) was made in 290 of these patients. The response of the index tumor on pre- and post-TACE magnetic resonance images was assessed retrospectively in 78 treatment-naïve patients with HCC (63 male; mean age, 63 years ± 11 [standard deviation]). Each response assessment method (RECIST, mRECIST, EASL, and 3D methods of volumetric RECIST [vRECIST] and quantitative EASL [qEASL]) was used to classify patients as responders or nonresponders by following standard guidelines for the uni- and bidimensional measurements and by using the formula for a sphere for the 3D measurements. The Kaplan-Meier method with the log-rank test was performed for each method to evaluate its ability to help predict survival of responders and nonresponders. Uni- and multivariate Cox proportional hazard ratio models were used to identify covariates that had significant association with survival. Results The uni- and bidimensional measurements of RECIST (hazard ratio, 0.6; 95% confidence interval [CI]: 0.3, 1.0; P = .09), mRECIST (hazard ratio, 0.6; 95% CI: 0.6, 1.0; P = .05), and EASL (hazard ratio, 1.1; 95% CI: 0.6, 2.2; P = .75) did not show a significant difference in survival between responders and nonresponders, whereas vRECIST (hazard ratio, 0.6; 95% CI: 0.3, 1

  16. Outbreaks source: A new mathematical approach to identify their possible location

    NASA Astrophysics Data System (ADS)

    Buscema, Massimo; Grossi, Enzo; Breda, Marco; Jefferson, Tom

    2009-11-01

    Classical epidemiology has generally relied on the description and explanation of the occurrence of infectious diseases in relation to time occurrence of events rather than to place of occurrence. In recent times, computer generated dot maps have facilitated the modeling of the spread of infectious epidemic diseases either with classical statistics approaches or with artificial “intelligent systems”. Few attempts, however, have been made so far to identify the origin of the epidemic spread rather than its evolution by mathematical topology methods. We report on the use of a new artificial intelligence method (the H-PST Algorithm) and we compare this new technique with other well known algorithms to identify the source of three examples of infectious disease outbreaks derived from literature. The H-PST algorithm is a new system able to project a distances matrix of points (events) into a bi-dimensional space, with the generation of a new point, named hidden unit. This new hidden unit deforms the original Euclidean space and transforms it into a new space (cognitive space). The cost function of this transformation is the minimization of the differences between the original distance matrix among the assigned points and the distance matrix of the same points projected into the bi-dimensional map (or any different set of constraints). For many reasons we will discuss, the position of the hidden unit shows to target the outbreak source in many epidemics much better than the other classic algorithms specifically targeted for this task. Compared with main algorithms known in the location theory, the hidden unit was within yards of the outbreak source in the first example (the 2007 epidemic of Chikungunya fever in Italy). The hidden unit was located in the river between the two village epicentres of the spread exactly where the index case was living. Equally in the second (the 1967 foot and mouth disease epidemic in England), and the third (1854 London Cholera epidemic

  17. Sorafenib in advanced melanoma: a Phase II randomised discontinuation trial analysis.

    PubMed

    Eisen, T; Ahmad, T; Flaherty, K T; Gore, M; Kaye, S; Marais, R; Gibbens, I; Hackett, S; James, M; Schuchter, L M; Nathanson, K L; Xia, C; Simantov, R; Schwartz, B; Poulin-Costello, M; O'Dwyer, P J; Ratain, M J

    2006-09-01

    The effects of sorafenib--an oral multikinase inhibitor targeting the tumour and tumour vasculature--were evaluated in patients with advanced melanoma enrolled in a large multidisease Phase II randomised discontinuation trial (RDT). Enrolled patients received a 12-week run-in of sorafenib 400 mg twice daily (b.i.d.). Patients with changes in bi-dimensional tumour measurements <25% from baseline were then randomised to sorafenib or placebo for a further 12 weeks (ie to week 24). Patients with > or =25% tumour shrinkage after the run-in continued on open-label sorafenib, whereas those with > or =25% tumour growth discontinued treatment. This analysis focussed on secondary RDT end points: changes in bi-dimensional tumour measurements from baseline after 12 weeks and overall tumour responses (WHO criteria) at week 24, progression-free survival (PFS), safety and biomarkers (BRAF, KRAS and NRAS mutational status). Of 37 melanoma patients treated during the run-in phase, 34 were evaluable for response: one had > or =25% tumour shrinkage and remained on open-label sorafenib; six (16%) had <25% tumour growth and were randomised (placebo, n=3; sorafenib, n=3); and 27 had > or =25% tumour growth and discontinued. All three randomised sorafenib patients progressed by week 24; one remained on sorafenib for symptomatic relief. All three placebo patients progressed by week-24 and were re-started on sorafenib; one experienced disease re-stabilisation. Overall, the confirmed best responses for each of the 37 melanoma patients who received sorafenib were 19% stable disease (SD) (ie n=1 open-label; n=6 randomised), 62% (n=23) progressive disease (PD) and 19% (n=7) unevaluable. The overall median PFS was 11 weeks. The six randomised patients with SD had overall PFS values ranging from 16 to 34 weeks. The most common drug-related adverse events were dermatological (eg rash/desquamation, 51%; hand-foot skin reaction, 35%). There was no relationship between V600E BRAF status and disease

  18. Room-Temperature AlGaN/GaN Terahertz Plasmonic Detectors with a Zero-Bias Grating

    NASA Astrophysics Data System (ADS)

    Spisser, H.; Grimault-Jacquin, A.-S.; Zerounian, N.; Aassime, A.; Cao, L.; Boone, F.; Maher, H.; Cordier, Y.; Aniel, F.

    2016-03-01

    In this paper, we present sensitivity measurement as well as measured and calculated absorption spectra for AlGaN/GaN THz plasmonic detector made of a metallic grating in-between two ohmic contacts. Detectors with different grating patterns have been fabricated and their sensitivity, reaching 1.9 μA/W at 77 K and 0.7 μA/W at 300 K, measured with a voltage applied between the ohmic contacts. It is the first time that such a detector shows THz detection with no voltage applied on the grating, namely with a bidimensional electron gas (2DEG) having a homogeneous electron density. These results are consistent with detection by drag-effect rectification. Measurements held between 0.648 and 0.690 THz show that the dependence of the sensitivity on the frequency follows the absorption spectrum, indicating that absorption is a crucial step in the detection process. Further simulations of absorption spectra show the tunability offered by such detector and allow us to predict frequency behavior for grating-biased detectors as well, in which the rectification is mainly governed by ratchet effect.

  19. A scintillating fiber dosimeter for radiotherapy

    NASA Astrophysics Data System (ADS)

    Bartesaghi, G.; Conti, V.; Bolognini, D.; Grigioni, S.; Mascagna, V.; Prest, M.; Scazzi, S.; Mozzanica, A.; Cappelletti, P.; Frigerio, M.; Gelosa, S.; Monti, A.; Ostinelli, A.; Giannini, G.; Vallazza, E.

    2007-10-01

    Radiotherapy, together with chemotherapy and surgery, is one of the main methods applied in the fight against cancer; in order to increase the chances of a successful radiotherapy treatment the dose delivery to the tumor and the surrounding normal tissues has to be computed with high accuracy. Traditional dosimeters are accurate but single channel (ionization chambers and diodes) or non real-time (radiographic films) devices. At present there is no device water equivalent that can perform real-time and bidimensional measurements of a dose distribution. This article describes the development of a real-time dosimeter based on scintillating fibers for photon and electron beams; the fibers are made of polystyrene, that is water equivalent and thus tissue equivalent, allowing a direct dose calculation. Three prototypes (single and multichannel) have been assembled, consisting in small scintillators coupled to white fibers that carry the light to photomultiplier tubes. In this article the prototypes and the readout electronics are described, together with the results of the measurements with electron and photon beams with energy up to 20 MeV (produced by linear accelerators Varian Clinac 1800 and 2100CD).

  20. Emotion expression in body action and posture.

    PubMed

    Dael, Nele; Mortillaro, Marcello; Scherer, Klaus R

    2012-10-01

    Emotion communication research strongly focuses on the face and voice as expressive modalities, leaving the rest of the body relatively understudied. Contrary to the early assumption that body movement only indicates emotional intensity, recent studies have shown that body movement and posture also conveys emotion specific information. However, a deeper understanding of the underlying mechanisms is hampered by a lack of production studies informed by a theoretical framework. In this research we adopted the Body Action and Posture (BAP) coding system to examine the types and patterns of body movement that are employed by 10 professional actors to portray a set of 12 emotions. We investigated to what extent these expression patterns support explicit or implicit predictions from basic emotion theory, bidimensional theory, and componential appraisal theory. The overall results showed partial support for the different theoretical approaches. They revealed that several patterns of body movement systematically occur in portrayals of specific emotions, allowing emotion differentiation. Although a few emotions were prototypically expressed by one particular pattern, most emotions were variably expressed by multiple patterns, many of which can be explained as reflecting functional components of emotion such as modes of appraisal and action readiness. It is concluded that further work in this largely underdeveloped area should be guided by an appropriate theoretical framework to allow a more systematic design of experiments and clear hypothesis testing. PMID:22059517

  1. Antifungal Metabolites from the Roots of Diospyros virginiana by Overpressure Layer Chromatography

    PubMed Central

    Wang, Xiaoning; Habib, Eman; León, Francisco; Radwan, Mohamed M.; Tabanca, Nurhayat; Gao, Jiangtao

    2011-01-01

    A preparative overpressure layer chromatography (OPLC) method was successfully used for the separation of two new natural compounds, 4-hydroxy-5,6-dimethoxy-2-naphthaldehyde (1) and Δ12,13-20,29-dihydrobetulin (2) together with nine known compounds including 7-methyl-juglone (3), diospyrin (4), isodiospyrin (5), shinanolone (6), lupeol (7), betulin (8), betulinic acid (9), betulinaldehyde (10), and ursolic acid (11) from the acetone extract of the roots of Diospyros virginiana. Their identification was performed with mono and bidimensional NMR spectroscopy and HR-ESI-MS methods. All the isolated compounds were evaluated for their antifungal activity against Colletotrichum fragariae, C. gloeosporioides, C. acutatum, Botrytis cinerea, Fusarium oxysporum, Phomopsis obscurans, and P. viticola using in vitro micro-dilution broth assay. The results indicated that compounds 3 and 5 showed high antifungal activity against P. obscurans at 30 μM with 97.0 % and 81.4 % growth inhibition and moderate activity against P. viticola (54.3 % and 36.6 %). It appears that an optimized OPLC system offers a rapid and efficient method of exploiting bioactive natural products. PMID:22162171

  2. The University of Bern Atmospheric Ion Model: Time-dependent modeling of the ions in the mesosphere and lower thermosphere

    NASA Astrophysics Data System (ADS)

    Kazil, Jan; Kopp, Ernest; Chabrillat, Simon; Bishop, James

    2003-07-01

    In this paper the first time-dependent model of ion chemistry in the mesosphere/lower thermosphere (MLT) region acting within a global, time-dependent, two-dimensional neutral atmosphere model is described. Selected diurnal results are presented for undisturbed solar minimum conditions. The University of Bern Atmospheric Ion Model (UBAIM) is a time-dependent, pseudo-two-dimensional model of the ion chemistry in the Earth atmosphere. It covers latitudes from 85°S to 85°N and (log-pressure) altitudes from 20 to 120 km. On this grid a system of differential equations describing the ion chemistry is integrated numerically until a periodical solution, governed by the diurnal changes in the incident radiation, is reached; this solution constitutes a model for quiet or undisturbed conditions. The basic ion chemistry of the UBAIM contains 311 reactions for 71 charged species. Ionization sources are solar X-ray and EUV radiation, resonantly scattered Lyman α and β photons, and galactic cosmic rays. Densities of main and trace neutral atmospheric constituents are taken from a new version of the bidimensional NCAR model SOCRATES, which has been specifically optimized for mesospheric and lower thermospheric processes with upper boundary conditions set using the empirical MSIS thermosphere model. Direct solar flux inputs are computed by the SOLAR2000 model; scattered Lyman α and β fluxes are calculated using geocoronal hydrogen density profiles consistent with the adopted MSIS density distributions.

  3. [Aortic intramural hematoma. An atypical pattern equivalent to aortic dissection].

    PubMed

    López-Mínguez, J R; Merchán, A; Arrobas, J; Fernández, G; González-Egüaras, M; García-Andoaín, J M; Alonso, M; Gamero, C; Poblador, M A; Alonso, F

    1995-09-01

    A case is presented of a hypertensive woman who had suffered a stabbing back pain for some three hours, with mild irradiation to precordium and accompanied by vegetative signs. A sinusal rhythm and negative T waves of little depth were seen on the ECG. A transthoracic bidimensional echocardiogram (TTE) showed a normal left ventricle with a somewhat dilated aortic root and the existence of a double echo running parallel to the anterior wall of the aorta but non-ondulating and without a visible intimal flap. Because of suspected aortic dissection an urgent contrasted CAT and a transesophageal echocardiogram were performed. These were informed as an aneurysm of the aortic root with mural thrombus from the ascending to descending aorta, but with no existing intimal flap suggesting dissection. A cardiac catheterization showed a mildly some dilated aortic root without dissection signs and normal left ventricle and coronary arteries. The patient was presented for surgical evaluation but, since no dissection was present, was not considered urgent surgery; she was admitted to the coronary unit and died 48 hours later in a situation of acute pericardial tamponade, documented by TTE, surely due to rupture of the aortic root to pericardial sack. This way of presenting threatened aorta rupture that has been only recently recognized is discussed, as well as some misconceptions which must be avoided. PMID:7569267

  4. Clustering and flow around a sphere moving into a grain cloud.

    PubMed

    Seguin, A; Lefebvre-Lepot, A; Faure, S; Gondret, P

    2016-06-01

    A bidimensional simulation of a sphere moving at constant velocity into a cloud of smaller spherical grains far from any boundaries and without gravity is presented with a non-smooth contact dynamics method. A dense granular "cluster" zone builds progressively around the moving sphere until a stationary regime appears with a constant upstream cluster size. The key point is that the upstream cluster size increases with the initial solid fraction [Formula: see text] but the cluster packing fraction takes an about constant value independent of [Formula: see text]. Although the upstream cluster size around the moving sphere diverges when [Formula: see text] approaches a critical value, the drag force exerted by the grains on the sphere does not. The detailed analysis of the local strain rate and local stress fields made in the non-parallel granular flow inside the cluster allows us to extract the local invariants of the two tensors: dilation rate, shear rate, pressure and shear stress. Despite different spatial variations of these invariants, the local friction coefficient μ appears to depend only on the local inertial number I as well as the local solid fraction, which means that a local rheology does exist in the present non-parallel flow. The key point is that the spatial variations of I inside the cluster do not depend on the sphere velocity and explore only a small range around the value one. PMID:27339702

  5. Nonequilibrium Equation of State in Suspensions of Active Colloids

    NASA Astrophysics Data System (ADS)

    Ginot, Félix; Theurkauff, Isaac; Levis, Demian; Ybert, Christophe; Bocquet, Lydéric; Berthier, Ludovic; Cottin-Bizonne, Cécile

    2015-01-01

    Active colloids constitute a novel class of materials composed of colloidal-scale particles locally converting chemical energy into motility, mimicking micro-organisms. Evolving far from equilibrium, these systems display structural organizations and dynamical properties distinct from thermalized colloidal assemblies. Harvesting the potential of this new class of systems requires the development of a conceptual framework to describe these intrinsically nonequilibrium systems. We use sedimentation experiments to probe the nonequilibrium equation of state of a bidimensional assembly of active Janus microspheres and conduct computer simulations of a model of self-propelled hard disks. Self-propulsion profoundly affects the equation of state, but these changes can be rationalized using equilibrium concepts. We show that active colloids behave, in the dilute limit, as an ideal gas with an activity-dependent effective temperature. At finite density, increasing the activity is similar to increasing adhesion between equilibrium particles. We quantify this effective adhesion and obtain a unique scaling law relating activity and effective adhesion in both experiments and simulations. Our results provide a new and efficient way to understand the emergence of novel phases of matter in active colloidal suspensions.

  6. Optical Coherence Tomography Angiography in Healthy Subjects.

    PubMed

    Coscas, Gabriel; Lupidi, Marco; Coscas, Florence

    2016-01-01

    Fluorescein angiography and indocyanine green angiography provide information about normal retinal and choroidal anatomy that is nearly comparable to histological findings. These results are absolutely fundamental for the evaluation of retinal and choroidal vascular diseases and allow the clinician to define and diagnose several pathological conditions. Fluorescein angiography has become the 'gold standard' in retinal imaging due to its capacity to allow visualization of the retinal capillary bed and its changes, particularly in the macular area. Although the fluorescence of the injected dye enables improved visualization of retinal capillaries, not all of the different layers of the retinal capillary network can be visualized using this bi-dimensional examination technique, possibly because of a light scattering phenomenon. Optical coherence tomography angiography allows depth-resolved visualization of the retinal and choroidal microvasculature by calculating the difference between static and nonstatic tissue. Given that the main moving elements in the eye fundus are contained within vessels, determining a vascular decorrelation signal enables three-dimensional visualization of the retinal and choroidal vascular network without the administration of intravenous dye and therefore reduces the risk of potential adverse events. PMID:27023473

  7. Evidence of viscoplastic behavior of exfoliated graphite nanofluids.

    PubMed

    Hermida-Merino, Carolina; Pérez-Rodríguez, Martín; Piñeiro, Manuel M; Pastoriza-Gallego, María José

    2016-02-17

    The rheological behavior of ethylene glycol-based nanofluids containing exfoliated graphite nanoplatelets has been carried out using a cone-plate Physica MCR rheometer. Initial experiments based on flow curves were carried out, the flow curves were based on the controlled shear stress model, these tests show that the studied nanofluids present non-Newtonian shear thinning behavior with yield stress. Furthermore, linear viscoelastic experiments were conducted in order to determine the viscoelastic behavior: using strain sweep and frequency sweep tests the storage and loss modulus were determined. The fractal dimension (Df) was estimated from the suspension static yield-stress and volume fraction (ϕ) dependence, and was determined to be Df = 2.36, a value consistent with a process of aggregation of RLCA type (reaction limited cluster aggregation). This value is unusual if compared with other nanofluids, and can be regarded as a result of the bidimensionality of the suspended nanoplatelets. Finally, creep-recovery tests and mechanical models confirm the viscoplastic nature of our nanofluids, a feature never shown so far for this type of systems, increasing the solid-like character in the range of concentrations studied if compared with other nanofluids reported in the literature. This is a result of the combination of a remarkable internal structure and strong interactions, which evidence an unexpected behaviour sharing many solid-like features. PMID:26822724

  8. Axon terminals from the nucleus isthmi pars parvocellularis control the ascending retinotectofugal output through direct synaptic contact with tectal ganglion cell dendrites.

    PubMed

    González-Cabrera, Cristian; Garrido-Charad, Florencia; Mpodozis, Jorge; Bolam, J Paul; Marín, Gonzalo J

    2016-02-01

    The optic tectum in birds and its homologue the superior colliculus in mammals both send major bilateral, nontopographic projections to the nucleus rotundus and caudal pulvinar, respectively. These projections originate from widefield tectal ganglion cells (TGCs) located in layer 13 in the avian tectum and in the lower superficial layers in the mammalian colliculus. The TGCs characteristically have monostratified arrays of brush-like dendritic terminations and respond mostly to bidimensional motion or looming features. In birds, this TGC-mediated tectofugal output is controlled by feedback signals from the nucleus isthmi pars parvocellularis (Ipc). The Ipc neurons display topographically organized axons that densely ramify in restricted columnar terminal fields overlapping various neural elements that could mediate this tectofugal control, including the retinal terminals and the TGC dendrites themselves. Whether the Ipc axons make synaptic contact with these or other tectal neural elements remains undetermined. We double labeled Ipc axons and their presumptive postsynaptic targets in the tectum of chickens (Gallus gallus) with neural tracers and performed an ultrastructural analysis. We found that the Ipc terminal boutons form glomerulus-like structures in the superficial and intermediate tectal layers, establishing asymmetric synapses with several dendritic profiles. In these glomeruli, at least two of the postsynaptic dendrites originated from TGCs. We also found synaptic contacts between retinal terminals and TGC dendrites. These findings suggest that, in birds, Ipc axons control the ascending tectal outflow of retinal signals through direct synaptic contacts with the TGCs. PMID:26224333

  9. Mother-Youth Acculturation Gaps and Health-Risking/Emotional Problems among Latin-American Adolescents.

    PubMed

    Wiesner, Margit; Arbona, Consuelo; Capaldi, Deborah M; Kim, Hyoun K; Kaplan, Charles D

    2015-01-01

    Second-generation Latin-American adolescents tend to show higher levels of various health-risking behaviors and emotional problems than first-generation Latin-American adolescents. This cross-sectional study of 40 mother-adolescent dyads examined the association of mother-youth acculturation gaps to youth adjustment problems. Intergenerational acculturation gaps were assessed as a bidimensional self-report component and a novel observational measurement component. The Latin-American adolescents were predominantly second-generation of Mexican descent (M age = 13.42 years, SD = 0.55). Most of the mothers were born in Mexico (M age = 39.18 years, SD = 5.17). Data were collected from mothers, adolescents, and coders, using questionnaires, structured interviews, and videotaped mother-youth interaction tasks. Findings revealed generally weak support for the acculturation gap-distress hypothesis. In addition, stronger relative adherence to their heritage culture by the adolescents was significantly (p < .05, ES = 0.15) related to less engagement in early health-risking sexual behaviors, possibly reflecting selective acculturation processes. Mother-youth acculturation gaps in orientation to the heritage culture were the most salient dimension, changing the focus on the original formulation of the acculturation gap-distress hypothesis. PMID:26190068

  10. Observation of neutral sodium above Mercury during the transit of November 8, 2006

    NASA Astrophysics Data System (ADS)

    Potter, A. E.; Killen, R. M.; Reardon, Kevin P.; Bida, T. A.

    2013-09-01

    We mapped the absorption of sunlight by sodium vapor in the exosphere of Mercury during the transit of Mercury on November 8, 2006, using the IBIS Interferometric BIdimensional Spectrometer at the Dunn Solar Telescope operated by the National Solar Observatory at Sunspot, New Mexico. The measurements were reduced to line-of-sight equivalent widths for absorption at the sodium D2 line around the shadow of Mercury. The sodium absorption fell off exponentially with altitude up to about 600 km. However there were regions around north and south polar-regions where relatively uniform sodium absorptions extended above 1000 km. We corrected the 0-600 km altitude profiles for seeing blur using the measured point spread function. Analysis of the corrected altitude distributions yielded surface densities, zenith column densities, temperatures and scale heights for sodium all around the planet. Sodium absorption on the dawn side equatorial terminator was less than on the dusk side, different from previous observations of the relative absorption levels. We also determined Earthward velocities for sodium atoms, and line widths for the absorptions. Earthward velocities resulting from radiation pressure on sodium averaged 0.8 km/s, smaller than a prediction of 1.5 km/s. Most line widths were in the range of 20 mA after correction for instrumental broadening, corresponding to temperatures in the range of 1000 K.

  11. Optimisation methods for bathymetry and open boundary conditions in finite element model of ocean tides

    SciTech Connect

    Lyard, F.; Genco, M.L.

    1994-10-01

    A bidimensional, spectral in time, quasi-linearised hydrodynamic ocean tide model has been developed at the Institut de Mecanique de Grenoble. This model is derived from the classical shallow water equations by removing the velocity unknowns in the continuity equation, that leads to an elliptic, second-order differential equation where tide denivellation remains the only unknown quantity. The problem is solved in its variational formulation and the finite elements method is used to discretise the equations in the spatial domain with a Lagrange-P2 approximation. Bottom topography has to be known at the integration points of the elements. In the case of the large oceanic basins, a specific method, called the bathymetry optimisation method, is needed to correctly take into account the bottom topography inside the model. The accuracy of the model`s solutions is also strongly dependent on the quality of the open boundary conditions because of the elliptic characteristics of the problem. The optimisation method for open boundary conditions relies on the use of the in situ data available in the modelled domain. The aim of this paper is to present the basis of these optimisations of bathymetry and open boundary conditions. An illustration of the related improvements is presented on the North Atlantic Basin. 36 refs., 10 figs., 5 tabs.

  12. Finite elements study of the Flexi Post and Flexi Flange post systems in a maxillary central incisor.

    PubMed

    Lewgoy, Hugo Roberto; Youssef, Michel Nicolau; Matson, Maurício Rufaiel; Bocangel, Jorge Antônio Javier Saldivar; Netto, Camillo Anauate; Amore, Ricardo

    2003-01-01

    The use of post and core systems has become an excellent alternative for restoring endodontically treated teeth. The aim of this study was to evaluate the von Mises, maximal compressive and tensile stresses distribution using the Finite Element Method (FEM) on human teeth restored with different post and core systems. The analysis was made on endodontically treated maxillary central incisors. The post systems used in this investigation were the stainless steel or titanium Flexi Post/Flexi Flange. Composite resin was used as core material and resin cement was the cement material of choice to seat a full porcelain crown. The bi-dimensional mathematical model was created from pictures taken from an intact human maxillary central incisor and prefabricated posts. This image was transferred to a personal computer in the MSC/Nastran 4.5 software. A static and linear analysis treatment was performed when a 45 load of 100 N was applied on the lingual surface of the tooth. Based on the results obtained, it can be concluded that the post design and its material can alter the stress pattern distribution. PMID:14569354

  13. Numerical studies of fibrous composites from the view point of fiber-matrix interface and fiber-matrix bonding

    NASA Astrophysics Data System (ADS)

    Yilmaz, Yahya Ilyas

    In the present research, the micromechanics of fibrous composites was studied numerically. The effects of the fiber/matrix interphase region and fiber/matrix bonding were the main goals of this research. Throughout the research NASTRAN finite element analyses were used. First we investigated the effect of the interphase region on the stress field by varying the thickness of the interphase region and the material properties in the interphase region. Second, we numerically simulated the bonding qualities between the fiber and the matrix by the implementation of the fiber/matrix interphase region. The change for bonding between the fiber and the matrix were simulated through a periodic material property change in the interphase region. Third, we developed a bi-dimensional concentric cylindrical model for stress transfer between the fiber and the matrix model in case of a broken fiber or short fiber composites. This model is unique in accounting for the real non-linear stress-strain relationship for the matrix material. The stress transfer between the fiber and the matrix was also analyzed by finite element models. Toward this end finite element analysis proved a useful tool to help us evaluate key model parameters, most importantly the radius of fiber influence. This parameter is also a key parameter of simple models upon which the new model is based. Finally we applied our stress transfer model to analyze single fiber fragmentation test data obtained at Kansas State University.

  14. Oxidative damage of 14-3-3 zeta and gamma isoforms in Alzheimer's disease and cerebral amyloid angiopathy.

    PubMed

    Santpere, G; Puig, B; Ferrer, I

    2007-06-01

    Previous studies have shown oxidative damage resulting from amyloid Abeta exposure to cultured cells and in murine models. A target of oxidation is 14-3-3 which comprises a group of proteins involved in kinase activation and chaperone activity. The present study shows glycoxidative damage, as revealed with mono and bi-dimensional gel electrophoresis and Western blotting, followed by in-gel digestion and mass spectrometry, in the frontal cortex in Alzheimer's disease (AD) and cerebral amyloid angiopathy (CAA), a neurodegenerative disease with deposition of Abeta in cerebral blood vessels and in diffuse plaques unaccompanied by intraneuronal hyper-phosphorylated tau deposition. malondialdehyde-lysine (MDA-Lys)-, but not 4-hydroxy-2-nonenal (HNE)-immunoreactive adducts, and N-carboxyethyl-lysine (CEL), but not N-carboxymethyl-lysine (CML)-products, were present in 14-3-3 involving zeta and gamma isoforms in both AD and CAA. These findings demonstrate that 14-3-3 glyco- and lipoxidation occurs in AD and CAA, probably as a direct consequence of Abeta deposition. PMID:17445990

  15. On boredom: a close encounter with encapsulated parts of the psyche.

    PubMed

    Bergstein, Avner

    2009-06-01

    The psychoanalytical literature has numerous scattered references to the analyst's experience of boredom, especially amongst writers working with primitive mental states. In the present paper, the author tries to gather some of these references in an attempt to integrate the various facets of this widespread phenomenon, and reflect on some clinical issues and dilemmas it raises. It is suggested that the experience of boredom in analysis may be a reaction to an encounter with a hidden, encapsulated part of the psyche, a bidimensional area of experience in which mental activity has been suspended, and experience remains meaningless. This is a barren area of lack, an encounter with the autistic core of the psyche. However, boredom may also be an experiential expression of despair, a re-living of primitive object relations with an emotionally non-existent primary object. Through bringing the emptiness and desolation into analysis, the individual makes room for the empty, blunt, dead inner object which resides within him, and that needs to be integrated into the psyche. This inner object is a vital part of the patient's inner world, part of his history, and can neither be erased nor filled in order to eradicate the emptiness. This is illustrated by clinical material from patients along the spectrum of autism, autistic reaction following trauma and autistic barriers in neurotic patients. PMID:19580600

  16. Multifractal Surfaces: Lucena and Stanley Approaches

    NASA Astrophysics Data System (ADS)

    Corso, G.; Moreira, D. A.

    2013-12-01

    We review multifractal surfaces focusing on a comparison between Lucena and Stanley approaches. The multifractal model as presented by Stanley is basically a multinomial measure over a standard partition of a square. The Lucena approach is geometric oriented, the multifractality is not imposed over a regular lattice, but the lattice itself follows a partition where area tiles obey a multifractal distribution. The non-trivial tilling has a distribution of neighbors of lattice elements that shows a fat tail. Despite the strong differences in the two bidimensional models, both Liacir and Stanley multifractals can be reduced to the same object in one dimension. The message of this article is that there is no unique multifractal object in two dimensions and, as a consequence, we should caution about algorithms that estimate multifractal spectrum in two dimensions because it is not clear what kind of multifractality is being measured. Finally we propose a mixed Lucena-Stanley bimultifractal, an object that combines a multifractal measure over a geometric multifractal tilling.

  17. Multifractal surfaces: Lucena and Stanley approaches

    NASA Astrophysics Data System (ADS)

    Corso, G.; Moreira, D. A.

    2014-03-01

    We review multifractal surfaces focusing on a comparison between Lucena and Stanley approaches. The multifractal model as presented by Stanley is basically a multinomial measure over a standard partition of a square. The Lucena approach is geometric oriented, the multifractality is not imposed over a regular lattice, but the lattice itself follows a partition where area tiles obey a multifractal distribution. The non-trivial tilling has a distribution of neighbors of lattice elements that shows a fat tail. Despite the strong differences in the two bidimensional models, both Liacir and Stanley multifractals can be reduced to the same object in one dimension. The message of this article is that there is no unique multifractal object in two dimensions and, as a consequence, we should caution about algorithms that estimate multifractal spectrum in two dimensions because it is not clear what kind of multifractality is being measured. Finally we propose a mixed Lucena-Stanley bimultifractal, an object that combines a multifractal measure over a geometric multifractal tilling.

  18. Metabolomics of meat exudate: Its potential to evaluate beef meat conservation and aging.

    PubMed

    Castejón, David; García-Segura, Juan Manuel; Escudero, Rosa; Herrera, Antonio; Cambero, María Isabel

    2015-12-11

    In this study we analyzed the exudate of beef to evaluate its potential as non invasive sampling for nuclear magnetic resonance (NMR) based metabolomic analysis of meat samples. Exudate, as the natural juice from raw meat, is an easy to obtain matrix that it is usually collected in small amounts in commercial meat packages. Although meat exudate could provide complete and homogeneous metabolic information about the whole meat piece, this sample has been poorly studied. Exudates from 48 beef samples of different breeds, cattle and storage times have been studied by (1)H NMR spectroscopy. The liquid exudate spectra were compared with those obtained by High Resolution Magic Angle Spinning (HRMAS) of the original meat pieces. The close correlation found between both spectra (>95% of coincident peaks in both registers; Spearman correlation coefficient = 0.945) lead us to propose the exudate as an excellent alternative analytical matrix with a view to apply meat metabolomics. 60 metabolites could be identified through the analysis of mono and bidimensional exudate spectra, 23 of them for the first time in NMR meat studies. The application of chemometric tools to analyze exudate dataset has revealed significant metabolite variations associated with meat aging. Hence, NMR based metabolomics have made it possible both to classify meat samples according to their storage time through Principal Component Analysis (PCA), and to predict that storage time through Partial Least Squares (PLS) regression. PMID:26614053

  19. [Current possibilities of echography in pneumological diagnosis (preliminary note)].

    PubMed

    Anastasatu, C; Burnea, D; Pop, T; Petcu, E

    1982-01-01

    Various types of echographies are presented, and it is concluded that the bi-dimensional echography, also called type B or echo-tomography is the most useful for the study of pulmonary affections, and of compact formations in contact with the pulmonary tissues. With the aid of Model E.D.B. Unirad sonograph (Technicare, USA), and of the Scintron 5 computer (Scintag, Berthold, Switzerland) 6 patients with pleurisy of various extension, one patient with fibrothorax, and 2 patients with pulmonary tumours have been examined. Five of the cases are presented. Echotomography has demonstrated its usefulness in measuring the thickness of the thoracic wall, in establishing by means of a non-invasive technique the solid or fluid character of pleural affections, in assessing the structure of pachypleuritis and in detecting changes induced by tumours, or atelectasia in the vicinity of the pleura. However, the method does not provide information on round peripheral tumours which do not come into contact with the pleura. Also this method cannot replace other methods already used in the pneumological practice, but can provide supplementary informations without any risks for the patient. PMID:6294805

  20. Interaction of Cu(II) and Ni(II) with Ypk9 Protein Fragment via NMR Studies

    PubMed Central

    Peana, Massimiliano Francesco; Medici, Serenella; Ledda, Alessia; Nurchi, Valeria Marina; Zoroddu, Maria Antonietta

    2014-01-01

    P1D2E3K4H5E6L7 (PK9-H), a fragment of Ypk9, the yeast homologue of the human Park9 protein, was studied for its coordination abilities towards Ni(II) and Cu(II) ions through mono- and bi-dimensional NMR techniques. Both proteins are involved in the transportation of metal ions, including manganese and nickel, from the cytosol to the lysosomal lumen. Ypk9 showed manganese detoxification role, preventing a Mn-induced Parkinsonism (PD) besides mutations in Park9, linked to a juvenile form of the disease. Here, we tested PK9-H with Cu(II) and Ni(II) ions, the former because it is an essential element ubiquitous in the human body, so its trafficking should be strictly regulated and one cannot exclude that Ypk9 may play a role in it, and the latter because, besides being a toxic element for many organisms and involved in different pathologies and inflammation states, it seems that the protein confers protection against it. NMR experiments showed that both cations can bind PK9-H in an effective way, leading to complexes whose coordination mode depends on the pH of the solution. NMR data have been used to build a model for the structure of the major Cu(II) and Ni(II) complexes. Structural changes in the conformation of the peptide with organized side chain orientation promoted by nickel coordination were detected. PMID:24790577

  1. Fast readout architectures for large arrays of digital pixels: examples and applications.

    PubMed

    Gabrielli, A

    2014-01-01

    Modern pixel detectors, particularly those designed and constructed for applications and experiments for high-energy physics, are commonly built implementing general readout architectures, not specifically optimized in terms of speed. High-energy physics experiments use bidimensional matrices of sensitive elements located on a silicon die. Sensors are read out via other integrated circuits bump bonded over the sensor dies. The speed of the readout electronics can significantly increase the overall performance of the system, and so here novel forms of readout architectures are studied and described. These circuits have been investigated in terms of speed and are particularly suited for large monolithic, low-pitch pixel detectors. The idea is to have a small simple structure that may be expanded to fit large matrices without affecting the layout complexity of the chip, while maintaining a reasonably high readout speed. The solutions might be applied to devices for applications not only in physics but also to general-purpose pixel detectors whenever online fast data sparsification is required. The paper presents also simulations on the efficiencies of the systems as proof of concept for the proposed ideas. PMID:24778588

  2. A study on large coherent structures and noise emission in a turbulent round jet

    NASA Astrophysics Data System (ADS)

    Wan, ZhenHua; Zhou, Lin; Sun, DeJun

    2014-08-01

    A moderate Reynolds number, and high subsonic turbulent round jet is investigated by large eddy simulation. The detailed results (e.g. mean flow properties, turbulence intensities, etc.) are validated against the experimental data, and special attention is paid to study motions of coherent structures and their contributions to far-field noise. Eulerian methods (e.g. Q-criteria and λ2 criteria) are utilized for visualizing coherent structures directly for instantaneous flow fields, and Lagrangian coherent structures accounting for integral effect are shown via calculating fields of finite time Lyapunov exponents based on bidimensional velocity fields. All visualizations demonstrate that intrusion of three-dimensional vortical structures into jet core occurs intermittently at the end of the potential core, resulting from the breakdown of helical vortex rings in the shear layer. Intermittencies in the shear layer and on the centerline are studied quantitatively, and distinctively different distributions of probability density function are observed. Moreover, the physical sound sources are obtained through a filtering operation of defined sources in Lighthill's analogy, and their distributions verify that intrusion of vortical structures into the core region serves as important sound sources, in particular for noise at aft angles. The facts that intermittent behaviors are caused by motions of coherent structures and correlated with noise generation imply that to establish reasonable sound sources in active noise production region based on intermittent coherent structures is one of the key issues for far-field noise prediction.

  3. Human osteoarthritic chondrocytes exposed to extremely low-frequency electromagnetic fields (ELF) and therapeutic application of musically modulated electromagnetic fields (TAMMEF) systems: a comparative study.

    PubMed

    Corallo, Claudio; Volpi, Nila; Franci, Daniela; Vannoni, Daniela; Leoncini, Roberto; Landi, Giacomo; Guarna, Massimo; Montella, Antonio; Albanese, Antonietta; Battisti, Emilio; Fioravanti, Antonella; Nuti, Ranuccio; Giordano, Nicola

    2013-06-01

    Osteoarthritis (OA) is the most common joint disease, characterized by matrix degradation and changes in chondrocyte morphology and metabolism. Literature reported that electromagnetic fields (EMFs) can produce benefits in OA patients, even if EMFs mechanism of action is debated. Human osteoarthritic chondrocytes isolated from femoral heads were cultured in vitro in bidimensional (2-D) flasks and in three-dimensional (3-D) alginate beads to mimic closely cartilage environment in vivo. Cells were exposed 30 min/day for 2 weeks to extremely low-frequency electromagnetic field (ELF) with fixed frequency (100 Hz) and to therapeutic application of musically modulated electromagnetic field (TAMMEF) with variable frequencies, intensities, and waveforms. Cell viability was measured at days 7 and 14, while healthy-cell density, heavily vacuolized (hv) cell density, and cluster density were measured by light microscopy only for 3-D cultures after treatments. Cell morphology was observed for 2-D and 3-D cultures by transmission electron microscopy (TEM). Chondrocyte exposure to TAMMEF enhances cell viability at days 7 and 14 compared to ELF. Light microscopy analysis showed that TAMMEF enhances healthy-cell density, reduces hv-cell density and clustering, compared to ELF. Furthermore, TEM analysis showed different morphology for 2-D (fibroblast-like) and 3-D (rounded shape) cultures, confirming light microscopy results. In conclusion, EMFs are effective and safe for OA chondrocytes. TAMMEF can positively interfere with OA chondrocytes representing an innovative non-pharmacological approach to treat OA. PMID:23263545

  4. Effectiveness and efficiency in clinical orthodontic practice.

    PubMed

    Rinchuse, Daniel J; Cozzani, Mauro

    2015-12-01

    Proffitt et al. have described "effectiveness and efficiency" (E&E) as achieving desired results without wasting the orthodontist's and patients' time. In 1972, Archibald Cochrane published a monograph entitled "Effectiveness and Efficiency," which challenged the medical community to use medical protocols that were evidence-based. As a possible starting point for E&E, the orthodontist could consider an "Evidence-based clinical practice" (EBCP) model, which integrates the best research evidence with clinical expertise and patient values. This model considers scientific or evidence-based orthodontics (EBO) together with patient preferences and patient autonomy, clinical or patient circumstances, and clinical experience and judgment. In this paper, therefore, E&E will be discussed from an EBCP perspective which, for our purposes, includes relevant evidence but also our clinical experience and rationale. We will discuss: wire sequence; NiTi Wire types; space closure by sliding; canine retraction versus en masse retraction, 18" slot versus 22" slot, the Bidimensional System; self-ligating brackets (SL); vertical slot; economic aspects. PMID:26527490

  5. Ex-vivo multi-modal microscopy of healthy skin

    NASA Astrophysics Data System (ADS)

    Guevara, Edgar; Gutiérrez-Hernández, José Manuel; Castonguay, Alexandre; Lesage, Frédéric; González, Francisco Javier

    2014-09-01

    The thorough characterization of skin samples is a critical step in investigating dermatological diseases. The combination of depth-sensitive anatomical imaging with molecular imaging has the potential to provide vast information about the skin. In this proof-of-concept work we present high-resolution mosaic images of skin biopsies using Optical Coherence Tomography (OCT) manually co-registered with standard microscopy, bi-dimensional Raman spectral mapping and fluorescence imaging. A human breast skin sample, embedded in paraffin, was imaged with a swept-source OCT system at 1310 nm. Individual OCT volumes were acquired in fully automated fashion in order to obtain a large field-of-view at high resolution (~10μm). Based on anatomical features, the other three modalities were manually co-registered to the projected OCT volume, using an affine transformation. A drawback is the manual co-registration, which may limit the utility of this method. However, the results indicate that multiple imaging modalities provide complementary information about the sample. This pilot study suggests that multi-modal microscopy may be a valuable tool in the characterization of skin biopsies.

  6. Multidimensional Human Dynamics in Mobile Phone Communications

    PubMed Central

    Quadri, Christian; Zignani, Matteo; Capra, Lorenzo; Gaito, Sabrina; Rossi, Gian Paolo

    2014-01-01

    In today's technology-assisted society, social interactions may be expressed through a variety of techno-communication channels, including online social networks, email and mobile phones (calls, text messages). Consequently, a clear grasp of human behavior through the diverse communication media is considered a key factor in understanding the formation of the today's information society. So far, all previous research on user communication behavior has focused on a sole communication activity. In this paper we move forward another step on this research path by performing a multidimensional study of human sociality as an expression of the use of mobile phones. The paper focuses on user temporal communication behavior in the interplay between the two complementary communication media, text messages and phone calls, that represent the bi-dimensional scenario of analysis. Our study provides a theoretical framework for analyzing multidimensional bursts as the most general burst category, that includes one-dimensional bursts as the simplest case, and offers empirical evidence of their nature by following the combined phone call/text message communication patterns of approximately one million people over three-month period. This quantitative approach enables the design of a generative model rooted in the three most significant features of the multidimensional burst - the number of dimensions, prevalence and interleaving degree - able to reproduce the main media usage attitude. The other findings of the paper include a novel multidimensional burst detection algorithm and an insight analysis of the human media selection process. PMID:25068479

  7. Evaluation of Central and Peripheral Fatigue in the Quadriceps Using Fractal Dimension and Conduction Velocity in Young Females

    PubMed Central

    Beretta-Piccoli, Matteo; D’Antona, Giuseppe; Barbero, Marco; Fisher, Beth; Dieli-Conwright, Christina M.; Clijsen, Ron; Cescon, Corrado

    2015-01-01

    Purpose Over the past decade, linear and non-linear surface electromyography descriptors for central and peripheral components of fatigue have been developed. In the current study, we tested fractal dimension (FD) and conduction velocity (CV) as myoelectric descriptors of central and peripheral fatigue, respectively. To this aim, we analyzed FD and CV slopes during sustained fatiguing contractions of the quadriceps femoris in healthy humans. Methods A total of 29 recreationally active women (mean age±standard deviation: 24±4 years) and two female elite athletes (one power athlete, age 24 and one endurance athlete, age 30 years) performed two knee extensions: (1) at 20% maximal voluntary contraction (MVC) for 30 s, and (2) at 60% MVC held until exhaustion. Surface EMG signals were detected from the vastus lateralis and vastus medialis using bidimensional arrays. Results Central and peripheral fatigue were described as decreases in FD and CV, respectively. A positive correlation between FD and CV (R=0.51, p<0.01) was found during the sustained 60% MVC, probably as a result of simultaneous motor unit synchronization and a decrease in muscle fiber CV during the fatiguing task. Conclusions Central and peripheral fatigue can be described as changes in FD and CV, at least in young, healthy women. The significant correlation between FD and CV observed at 60% MVC suggests that a mutual interaction between central and peripheral fatigue can arise during submaximal isometric contractions. PMID:25880369

  8. Compact interferometer transducer based on surface plasmon phase resonance.

    PubMed

    Hadjar, Yassine; Renault, Mikael; Blaize, Sylvain; Bruyant, Aurélien; Vincent, Rémi; Hmima, Abdelhamid

    2015-05-01

    We propose a new monolithic interferometric configuration and implement a novel method for spectroscopic phase shift detection of surface plasmon resonance (SPR) sensors. The interference pattern is obtained using a nonpolarizing beam splitter cube with two attached right angle prisms in such a way that each interference field undergoes two total internal reflections (TIR) at prisms/air interface and one attenuated total reflection (ATR) through surface plasmon interaction. The evanescent part of the interferogram around the Zero optical path difference (ZOPD) is sampled and detected in the far field, thanks to a bidimensional array of scattering optical near-field probes deposited on the corresponding prism surface. A Fourier transform of the sampled interferogram is performed to measure the input light wavelength, while a direct comparison of the interferogram in TM and TE polarization modes allows us to determine the differential phase shift induced by the SPR layer. The phase shift measurement is made possible thanks to a remarkable time stability of the interferogram in the glass bulk. By tuning the input laser wavelength around the resonance, we show a good agreement between experimental and theoretical calculations for both amplitude and phase spectral responses. PMID:26366899

  9. Aggregation behavior of amphiphilic cyclodextrins in a nonpolar solvent: evidence of large-scale structures by atomistic molecular dynamics simulations and solution studies.

    PubMed

    Raffaini, Giuseppina; Ganazzoli, Fabio; Mazzaglia, Antonino

    2016-01-01

    Chemically modified cyclodextrins carrying both hydrophobic and hydrophilic substituents may form supramolecular aggregates or nanostructures of great interest. These systems have been usually investigated and characterized in water for their potential use as nanocarriers for drug delivery, but they can also aggregate in apolar solvents, as shown in the present paper through atomistic molecular dynamics simulations and dynamic light scattering measurements. The simulations, carried out with a large number of molecules in vacuo adopting an unbiased bottom-up approach, suggest the formation of bidimensional structures with characteristic length scales of the order of 10 nm, although some of these sizes are possibly affected by the assumed periodicity of the simulation cell, in particular at longer lengths. In any case, these nanostructures are stable at least from the kinetic viewpoint for relatively long times thanks to the large number of intermolecular interactions of dipolar and dispersive nature. The dynamic light scattering experiments indicate the presence of aggregates with a hydrodynamic radius of the order of 80 nm and a relatively modest polydispersity, even though smaller nanometer-sized aggregates cannot be fully ruled out. Taken together, these simulation and experimental results indicate that amphiphilically modified cyclodextrins do also form large-scale nanoaggregates even in apolar solvents. PMID:26877809

  10. Aggregation behavior of amphiphilic cyclodextrins in a nonpolar solvent: evidence of large-scale structures by atomistic molecular dynamics simulations and solution studies

    PubMed Central

    Ganazzoli, Fabio; Mazzaglia, Antonino

    2016-01-01

    Summary Chemically modified cyclodextrins carrying both hydrophobic and hydrophilic substituents may form supramolecular aggregates or nanostructures of great interest. These systems have been usually investigated and characterized in water for their potential use as nanocarriers for drug delivery, but they can also aggregate in apolar solvents, as shown in the present paper through atomistic molecular dynamics simulations and dynamic light scattering measurements. The simulations, carried out with a large number of molecules in vacuo adopting an unbiased bottom-up approach, suggest the formation of bidimensional structures with characteristic length scales of the order of 10 nm, although some of these sizes are possibly affected by the assumed periodicity of the simulation cell, in particular at longer lengths. In any case, these nanostructures are stable at least from the kinetic viewpoint for relatively long times thanks to the large number of intermolecular interactions of dipolar and dispersive nature. The dynamic light scattering experiments indicate the presence of aggregates with a hydrodynamic radius of the order of 80 nm and a relatively modest polydispersity, even though smaller nanometer-sized aggregates cannot be fully ruled out. Taken together, these simulation and experimental results indicate that amphiphilically modified cyclodextrins do also form large-scale nanoaggregates even in apolar solvents. PMID:26877809