Estimators for local non-Gaussianities
International Nuclear Information System (INIS)
Creminelli, P.; Senatore, L.; Zaldarriaga, M.
2006-05-01
We study the Likelihood function of data given f NL for the so-called local type of non-Gaussianity. In this case the curvature perturbation is a non-linear function, local in real space, of a Gaussian random field. We compute the Cramer-Rao bound for f NL and show that for small values of f NL the 3- point function estimator saturates the bound and is equivalent to calculating the full Likelihood of the data. However, for sufficiently large f NL , the naive 3-point function estimator has a much larger variance than previously thought. In the limit in which the departure from Gaussianity is detected with high confidence, error bars on f NL only decrease as 1/ln N pix rather than N pix -1/2 as the size of the data set increases. We identify the physical origin of this behavior and explain why it only affects the local type of non- Gaussianity, where the contribution of the first multipoles is always relevant. We find a simple improvement to the 3-point function estimator that makes the square root of its variance decrease as N pix -1/2 even for large f NL , asymptotically approaching the Cramer-Rao bound. We show that using the modified estimator is practically equivalent to computing the full Likelihood of f NL given the data. Thus other statistics of the data, such as the 4-point function and Minkowski functionals, contain no additional information on f NL . In particular, we explicitly show that the recent claims about the relevance of the 4-point function are not correct. By direct inspection of the Likelihood, we show that the data do not contain enough information for any statistic to be able to constrain higher order terms in the relation between the Gaussian field and the curvature perturbation, unless these are orders of magnitude larger than the size suggested by the current limits on f NL . (author)
Local features with large spiky non-Gaussianities during inflation
International Nuclear Information System (INIS)
Abolhasani, Ali Akbar; Firouzjahi, Hassan; Khosravi, Shahram; Sasaki, Misao
2012-01-01
We provide a dynamical mechanism to generate localized features during inflation. The local feature is due to a sharp waterfall phase transition which is coupled to the inflaton field. The key effect is the contributions of waterfall quantum fluctuations which induce a sharp peak on the curvature perturbation which can be as large as the background curvature perturbation from inflaton field. Due to non-Gaussian nature of waterfall quantum fluctuations a large spike non-Gaussianity is produced which is narrowly peaked at modes which leave the Hubble radius at the time of phase transition. The large localized peaks in power spectrum and bispectrum can have interesting consequences on CMB anisotropies
Detection of local non-Gaussianity with future observations
International Nuclear Information System (INIS)
Li Hong; Liu Jie
2012-01-01
In this Letter we estimate the primordial non-Gaussianity (PNG) by simulating future observations. We use the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) as an example and focus on the cross correlation signal between the galaxies and the Integrate Sachs-Wolfe (ISW) effect of CMB. Our result is optimistical. It shows the potential of LAMOST, particularly its quasar survey, in probing for the PNG by ISW - galaxy cross correlation. This study is particularly relevant because LAMOST is almost parallel to the timetable of the upcoming high precision Planck satellite.
Biasing and the search for primordial non-Gaussianity beyond the local type
Energy Technology Data Exchange (ETDEWEB)
Gleyzes, Jérôme; De Putter, Roland; Doré, Olivier [California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125 (United States); Green, Daniel, E-mail: jerome.l.gleyzes@jpl.nasa.gov, E-mail: rdputter@caltech.edu, E-mail: drgreen@cita.utoronto.ca, E-mail: olivier.p.dore@jpl.nasa.gov [Department of Physics, University of California, 366 LeConte hall, Berkeley, CA 94720 (United States)
2017-04-01
Primordial non-Gaussianity encodes valuable information about the physics of inflation, including the spectrum of particles and interactions. Significant improvements in our understanding of non-Gaussanity beyond Planck require information from large-scale structure. The most promising approach to utilize this information comes from the scale-dependent bias of halos. For local non-Gaussanity, the improvements available are well studied but the potential for non-Gaussianity beyond the local type, including equilateral and quasi-single field inflation, is much less well understood. In this paper, we forecast the capabilities of large-scale structure surveys to detect general non-Gaussianity through galaxy/halo power spectra. We study how non-Gaussanity can be distinguished from a general biasing model and where the information is encoded. For quasi-single field inflation, significant improvements over Planck are possible in some regions of parameter space. We also show that the multi-tracer technique can significantly improve the sensitivity for all non-Gaussianity types, providing up to an order of magnitude improvement for equilateral non-Gaussianity over the single-tracer measurement.
Probing primordial non-Gaussianity via iSW measurements with SKA continuum surveys
Energy Technology Data Exchange (ETDEWEB)
Raccanelli, Alvise; Doré, Olivier, E-mail: alvise@jhu.edu, E-mail: olivier.dore@caltech.edu [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States); Bacon, David J.; Maartens, Roy, E-mail: David.Bacon@port.ac.uk, E-mail: roy.maartens@gmail.com [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth P01 3FX (United Kingdom); and others
2015-01-01
The Planck CMB experiment has delivered the best constraints so far on primordial non-Gaussianity, ruling out early-Universe models of inflation that generate large non-Gaussianity. Although small improvements in the CMB constraints are expected, the next frontier of precision will come from future large-scale surveys of the galaxy distribution. The advantage of such surveys is that they can measure many more modes than the CMB—in particular, forthcoming radio surveys with the Square Kilometre Array will cover huge volumes. Radio continuum surveys deliver the largest volumes, but with the disadvantage of no redshift information. In order to mitigate this, we use two additional observables. First, the integrated Sachs-Wolfe effect—the cross-correlation of the radio number counts with the CMB temperature anisotropies—helps to reduce systematics on the large scales that are sensitive to non-Gaussianity. Second, optical data allows for cross-identification in order to gain some redshift information. We show that, while the single redshift bin case can provide a σ(f{sub NL}) ∼ 20, and is therefore not competitive with current and future constraints on non-Gaussianity, a tomographic analysis could improve the constraints by an order of magnitude, even with only two redshift bins. A huge improvement is provided by the addition of high-redshift sources, so having cross-ID for high-z galaxies and an even higher-z radio tail is key to enabling very precise measurements of f{sub NL}. We use Fisher matrix forecasts to predict the constraining power in the case of no redshift information and the case where cross-ID allows a tomographic analysis, and we show that the constraints do not improve much with 3 or more bins. Our results show that SKA continuum surveys could provide constraints competitive with CMB and forthcoming optical surveys, potentially allowing a measurement of σ(f{sub NL}) ∼ 1 to be made. Moreover, these measurements would act as a useful check
Hot and Cold Spot Counts as Probes of Non-Gaussianity in the Cosmic Microwave Background
Chingangbam, Pravabati; Park, Changbom; Yogendran, K. P.; van de Weygaert, Rien
2012-01-01
We introduce the numbers of hot and cold spots, nh and nc , of excursion sets of the cosmic microwave background (CMB) temperature anisotropy maps as statistical observables that can discriminate different non-Gaussian models. We numerically compute them from simulations of non-Gaussian CMB
Vanishing of local non-Gaussianity in canonical single field inflation
Bravo, Rafael; Mooij, Sander; Palma, Gonzalo A.; Pradenas, Bastián
2018-05-01
We study the production of observable primordial local non-Gaussianity in two opposite regimes of canonical single field inflation: attractor (standard single field slow-roll inflation) and non attractor (ultra slow-roll inflation). In the attractor regime, the standard derivation of the bispectrum's squeezed limit using co-moving coordinates gives the well known Maldacena's consistency relation fNL = 5 (1‑ns) / 12. On the other hand, in the non-attractor regime, the squeezed limit offers a substantial violation of this relation given by fNL = 5/2. In this work we argue that, independently of whether inflation is attractor or non-attractor, the size of the observable primordial local non-Gaussianity is predicted to be fNLobs = 0 (a result that was already understood to hold in the case of attractor models). To show this, we follow the use of the so-called Conformal Fermi Coordinates (CFC), recently introduced in the literature. These coordinates parametrize the local environment of inertial observers in a perturbed FRW spacetime, allowing one to identify and compute gauge invariant quantities, such as n-point correlation functions. Concretely, we find that during inflation, after all the modes have exited the horizon, the squeezed limit of the 3-point correlation function of curvature perturbations vanishes in the CFC frame, regardless of the inflationary regime. We argue that such a cancellation should persist after inflation ends.
Toward the detection of gravitational waves under non-Gaussian noises I. Locally optimal statistic.
Yokoyama, Jun'ichi
2014-01-01
After reviewing the standard hypothesis test and the matched filter technique to identify gravitational waves under Gaussian noises, we introduce two methods to deal with non-Gaussian stationary noises. We formulate the likelihood ratio function under weakly non-Gaussian noises through the Edgeworth expansion and strongly non-Gaussian noises in terms of a new method we call Gaussian mapping where the observed marginal distribution and the two-body correlation function are fully taken into account. We then apply these two approaches to Student's t-distribution which has a larger tails than Gaussian. It is shown that while both methods work well in the case the non-Gaussianity is small, only the latter method works well for highly non-Gaussian case.
International Nuclear Information System (INIS)
Nishimichi, Takahiro
2012-01-01
The large-scale clustering pattern of biased tracers is known to be a powerful probe of the non-Gaussianities in the primordial fluctuations. The so-called scale-dependent bias has been reported in various type of models of primordial non-Gaussianities. We focus on local-type non-Gaussianities, and unify the derivations in the literature of the scale-dependent bias in the presence of multiple Gaussian source fields as well as higher-order coupling to cover the models described by frequently-discussed f NL , g NL and t NL parameterization. We find that the resultant power spectrum is characterized by two parameters responsible for the shape and the amplitude of the scale-dependent bias in addition to the Gaussian bias factor. We show how (a generalized version of) Suyama-Yamaguchi inequality between f NL and t NL can directly be accessible from the observed power spectrum through the dependence on our new parameter which controls the shape of the scale-dependent bias. The other parameter for the amplitude of the scale-dependent bias is shown to be useful to distinguish the simplest quadratic non-Gaussianities (i.e., f NL -type) from higher-order ones (g NL and higher), if one measures it from multiple species of galaxies or clusters of galaxies. We discuss the validity and limitations of our analytic results by comparison with numerical simulations in an accompanying paper
arXiv Probing non-Gaussian Stochastic Gravitational Wave Backgrounds with LISA
Bartolo, Nicola; Figueroa, Daniel G.; Garcia-Bellido, Juan; Peloso, Marco; Pieroni, Mauro; Ricciardone, Angelo; Sakellariadou, Mairi; Sorbo, Lorenzo; Tasinato, Gianmassimo
The stochastic gravitational wave background (SGWB) contains a wealth of information on astrophysical and cosmological processes. A major challenge of upcoming years will be to extract the information contained in this background and to disentangle the contributions of different sources. In this paper we provide the formalism to extract, from the correlation of three signals in the Laser Interferometer Space Antenna (LISA), information about the tensor three-point function, which characterizes the non-Gaussian properties of the SGWB. Compared to the two-point function, the SGWB three-point function has a richer dependence on the gravitational wave momenta and chiralities, and a larger number of signal channels. It can be used therefore as a powerful discriminator between different models. We provide LISA's response functions to a general SGWB three-point function. As examples, we study in full detail the cases of an equilateral and squeezed SGWB bispectra, and provide the explicit form of the response functio...
Directory of Open Access Journals (Sweden)
Zhu Xiao
2016-05-01
Full Text Available In this paper, a novel nonlinear framework of smoothing method, non-Gaussian delayed particle smoother (nGDPS, is proposed, which enables vehicle state estimation (VSE with high accuracy taking into account the non-Gaussianity of the measurement and process noises. Within the proposed method, the multivariate Student’s t-distribution is adopted in order to compute the probability distribution function (PDF related to the process and measurement noises, which are assumed to be non-Gaussian distributed. A computation approach based on Ensemble Kalman Filter (EnKF is designed to cope with the mean and the covariance matrix of the proposal non-Gaussian distribution. A delayed Gibbs sampling algorithm, which incorporates smoothing of the sampled trajectories over a fixed-delay, is proposed to deal with the sample degeneracy of particles. The performance is investigated based on the real-world data, which is collected by low-cost on-board vehicle sensors. The comparison study based on the real-world experiments and the statistical analysis demonstrates that the proposed nGDPS has significant improvement on the vehicle state accuracy and outperforms the existing filtering and smoothing methods.
Detectability of the effect of Inflationary non-Gaussianity on halo bias
Verde, Licia
2009-01-01
We consider the description of the clustering of halos for physically-motivated types of non-Gaussian initial conditions. In particular we include non-Gaussianity of the type arising from single field slow-roll, multi fields, curvaton (local type), higher-order derivative-type (equilateral), vacuum-state modifications (enfolded-type) and horizon-scale GR corrections type. We show that large-scale halo bias is a very sensitive tool to probe non-Gaussianity, potentially leading, for some planned surveys, to a detection of non-Gaussianity arising from horizon-scale GR corrections.
International Nuclear Information System (INIS)
Migliaccio, M.; Natoli, P.; De Troia, G.; Hikage, C.; Komatsu, E.; Ade, P.A.R.; Bock, J.J.; Bond, J.R.; Borrill, J.; Boscaleri, A.; Contaldi, C.R.; Crill, B.P.; Bernardis, P. de; Gasperis, G. de; Oliveira-Costa, A. de; Di Stefano, G.; Hivon, E.; Kisner, T.S.; Jones, W.C.; Lange, A.E.
2009-01-01
Minkowski functionals are a powerful tool to constrain the Gaussianity of the Cosmic Microwave Background (CMB). In the limit of a weakly non Gaussian field, a perturbative approach can be derived [Hikage C., Komatsu E., and Matsubara T., 2006, ApJ, 653, 11] that is completely based on analytical formulae without requiring computationally intensive, dedicated Monte Carlo non Gaussian simulations of the CMB anisotropy. We apply this machinery to an intensity map derived from the 1998 and 2003 flights of BOOMERanG, analyzed here together for the first time. We set limits on the non-linear coupling parameter f NL as -1020 NL <390 at 95% CL, markedly improving the previous constraints set by [De Troia G. et al., 2007, ApJ, 670, L73] whose analysis was limited to the BOOMERanG 2003 dataset. These limits are the most stringent ever set among suborbital experiments.
Energy Technology Data Exchange (ETDEWEB)
Migliaccio, M.; Natoli, P.; De Troia, G. [Dipartimento di Fisica, Universita di Roma ' Tor Vergata' , Via della Ricerca Scientifica, 1 I-00133 Roma (Italy); Hikage, C. [School of Physics and Astronomy, Cardiff University, Cardiff, CF24 3AA (United Kingdom); Komatsu, E. [Texas Cosmology Center, University of Texas at Austin, 1 University Station, C1400, Austin, TX 78712 (United States); Ade, P.A.R. [School of Physics and Astronomy, Cardiff University, Cardiff, CF24 3AA (United Kingdom); Bock, J.J. [Jet Propulsion Laboratory, Pasadena, CA (United States); Bond, J.R. [Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, Ontario (Canada); Borrill, J. [Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Boscaleri, A. [IFAC-CNR, Firenze (Italy); Contaldi, C.R. [Theoretical Physics Group, Imperial College, London (United Kingdom); Crill, B.P. [Jet Propulsion Laboratory, Pasadena, CA (United States); Bernardis, P. de [Dipartimento di Fisica, Universita La Sapienza, Roma (Italy); Gasperis, G. de [Dipartimento di Fisica, Universita di Roma ' Tor Vergata' , Via della Ricerca Scientifica, 1 I-00133 Roma (Italy); Oliveira-Costa, A. de [Department of Physics, MIT, Cambridge, MA 02139 (United States); Di Stefano, G. [Istituto Nazionale di Geofisica e Vulcanologia, 00143 Rome (Italy); Hivon, E. [Institut d' Astrophysique, Paris (France); Kisner, T.S. [Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Jones, W.C. [Department of Physics, Princeton University, Princeton, NJ 0854 (United States); Lange, A.E. [Observational Cosmology, California Institute of Technology, Pasadena, CA (United States)
2009-10-15
Minkowski functionals are a powerful tool to constrain the Gaussianity of the Cosmic Microwave Background (CMB). In the limit of a weakly non Gaussian field, a perturbative approach can be derived [Hikage C., Komatsu E., and Matsubara T., 2006, ApJ, 653, 11] that is completely based on analytical formulae without requiring computationally intensive, dedicated Monte Carlo non Gaussian simulations of the CMB anisotropy. We apply this machinery to an intensity map derived from the 1998 and 2003 flights of BOOMERanG, analyzed here together for the first time. We set limits on the non-linear coupling parameter f{sub NL} as -1020
Tachyon mediated non-Gaussianity
International Nuclear Information System (INIS)
Dutta, Bhaskar; Leblond, Louis; Kumar, Jason
2008-01-01
We describe a general scenario where primordial non-Gaussian curvature perturbations are generated in models with extra scalar fields. The extra scalars communicate to the inflaton sector mainly through the tachyonic (waterfall) field condensing at the end of hybrid inflation. These models can yield significant non-Gaussianity of the local shape, and both signs of the bispectrum can be obtained. These models have cosmic strings and a nearly flat power spectrum, which together have been recently shown to be a good fit to WMAP data. We illustrate with a model of inflation inspired from intersecting brane models.
Use of δN formalism-difficulties in generating large local-type non-Gaussianity during inflation
International Nuclear Information System (INIS)
Tanaka, Takahiro; Suyama, Teruaki; Yokoyama, Shuichiro
2010-01-01
We discuss the generation of non-Gaussianity in density perturbation through the super-horizon evolution during inflation by using the so-called δN formalism. We first provide a general formula for the nonlinearity parameter generated during inflation. We find that it is proportional to the slow-roll parameters, multiplied by the model-dependent factors that may enhance non-Gaussianity to the observable ranges. Then we discuss three typical examples to illustrate how difficult it is to generate sizable non-Gaussianity through the super-horizon evolution during inflation. The first example is the double inflation model, which shows that temporal violation of slow-roll conditions is not enough for the generation of non-Gaussianity. The second example is the ordinary hybrid inflation model, which illustrates the importance of taking into account perturbations on small scales. Finally, we discuss the Kadota-Stewart model. This model gives an example in which we have to choose rather unnatural initial conditions even if large non-Gaussianity can be generated.
Energy Technology Data Exchange (ETDEWEB)
Hoejstrup, J [NEG Micon Project Development A/S, Randers (Denmark); Hansen, K S [Denmarks Technical Univ., Dept. of Energy Engineering, Lyngby (Denmark); Pedersen, B J [VESTAS Wind Systems A/S, Lem (Denmark); Nielsen, M [Risoe National Lab., Wind Energy and Atmospheric Physics, Roskilde (Denmark)
1999-03-01
The pdf`s of atmospheric turbulence have somewhat wider tails than a Gaussian, especially regarding accelerations, whereas velocities are close to Gaussian. This behaviour is being investigated using data from a large WEB-database in order to quantify the amount of non-Gaussianity. Models for non-Gaussian turbulence have been developed, by which artificial turbulence can be generated with specified distributions, spectra and cross-correlations. The artificial time series will then be used in load models and the resulting loads in the Gaussian and the non-Gaussian cases will be compared. (au)
Komatsu, E; Afshordi, N; Bartolo, N; Baumann, D; Bond, J R; Buchbinder, E I; Byrnes, C T; Chen, X; Chung, D J H; Cooray, A; Creminelli, P; Dalal, N; Dore, O; Easther, R; Frolov, A V; Gorski, K M; Jackson, M G; Khoury, J; Kinney, W H; Kofman, L; Koyama, K; Leblond, L; Lehners, J L; Lidsey, J E; Liguori, M; Lim, E A; Linde, A; Lyth, D H; Maldacena, J; Matarrese, S; McAllister, L; McDonald, P; Mukohyama, S; Ovrut, B; Peiris, H V; Rath, C; Riotto, A; Rodriguez, Y; Sasaki, M; Scoccimarro, R; Seery, D; Sefusatti, E; Seljak, U; Senatore, L; Shandera, S; Shellard, E P S; Silverstein, E; Slosar, A; Smith, K M; Starobinsky, A A; Steinhardt, P J; Takahashi, F; Tegmark, M; Tolley, A J; Verde, L; Wandelt, B D; Wands, D; Weinberg, S; Wyman, M; Yadav, A P S; Zaldarriaga, M
2009-01-01
A new and powerful probe of the origin and evolution of structures in the Universe has emerged and been actively developed over the last decade. In the coming decade, non-Gaussianity, i.e., the study of non-Gaussian contributions to the correlations of cosmological fluctuations, will become an important probe of both the early and the late Universe. Specifically, it will play a leading role in furthering our understanding of two fundamental aspects of cosmology and astrophysics: (i) the physics of the very early universe that created the primordial seeds for large-scale structures, and (ii) the subsequent growth of structures via gravitational instability and gas physics at later times. To date, observations of fluctuations in the Cosmic Microwave Background (CMB) and the Large-Scale Structure of the Universe (LSS) have focused largely on the Gaussian contribution as measured by the two-point correlations (or the power spectrum) of density fluctuations. However, an even greater amount of information is contai...
Non-Gaussian halo assembly bias
International Nuclear Information System (INIS)
Reid, Beth A.; Verde, Licia; Dolag, Klaus; Matarrese, Sabino; Moscardini, Lauro
2010-01-01
The strong dependence of the large-scale dark matter halo bias on the (local) non-Gaussianity parameter, f NL , offers a promising avenue towards constraining primordial non-Gaussianity with large-scale structure surveys. In this paper, we present the first detection of the dependence of the non-Gaussian halo bias on halo formation history using N-body simulations. We also present an analytic derivation of the expected signal based on the extended Press-Schechter formalism. In excellent agreement with our analytic prediction, we find that the halo formation history-dependent contribution to the non-Gaussian halo bias (which we call non-Gaussian halo assembly bias) can be factorized in a form approximately independent of redshift and halo mass. The correction to the non-Gaussian halo bias due to the halo formation history can be as large as 100%, with a suppression of the signal for recently formed halos and enhancement for old halos. This could in principle be a problem for realistic galaxy surveys if observational selection effects were to pick galaxies occupying only recently formed halos. Current semi-analytic galaxy formation models, for example, imply an enhancement in the expected signal of ∼ 23% and ∼ 48% for galaxies at z = 1 selected by stellar mass and star formation rate, respectively
International Nuclear Information System (INIS)
McFadden, Paul; Skenderis, Kostas
2011-01-01
We investigate the non-Gaussianity of primordial cosmological perturbations within our recently proposed holographic description of inflationary universes. We derive a holographic formula that determines the bispectrum of cosmological curvature perturbations in terms of correlation functions of a holographically dual three-dimensional non-gravitational quantum field theory (QFT). This allows us to compute the primordial bispectrum for a universe which started in a non-geometric holographic phase, using perturbative QFT calculations. Strikingly, for a class of models specified by a three-dimensional super-renormalisable QFT, the primordial bispectrum is of exactly the factorisable equilateral form with f NL equil. = 5/36, irrespective of the details of the dual QFT. A by-product of this investigation is a holographic formula for the three-point function of the trace of the stress-energy tensor along general holographic RG flows, which should have applications outside the remit of this work
Galaxy bispectrum, primordial non-Gaussianity and redshift space distortions
Energy Technology Data Exchange (ETDEWEB)
Tellarini, Matteo; Ross, Ashley J.; Wands, David [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Portsmouth, PO1 3FX (United Kingdom); Tasinato, Gianmassimo, E-mail: matteo.tellarini@port.ac.uk, E-mail: ross.1333@osu.edu, E-mail: g.tasinato@swansea.ac.uk, E-mail: david.wands@port.ac.uk [Department of Physics, Swansea University, Singleton Park, Swansea, SA2 8PP (United Kingdom)
2016-06-01
Measurements of the non-Gaussianity of the primordial density field have the power to considerably improve our understanding of the physics of inflation. Indeed, if we can increase the precision of current measurements by an order of magnitude, a null-detection would rule out many classes of scenarios for generating primordial fluctuations. Large-scale galaxy redshift surveys represent experiments that hold the promise to realise this goal. Thus, we model the galaxy bispectrum and forecast the accuracy with which it will probe the parameter f {sub NL}, which represents the degree of primordial local-type non Gaussianity. Specifically, we address the problem of modelling redshift space distortions (RSD) in the tree-level galaxy bispectrum including f {sub NL}. We find novel contributions associated with RSD, with the characteristic large scale amplification induced by local-type non-Gaussianity. These RSD effects must be properly accounted for in order to obtain un-biased measurements of f {sub NL} from the galaxy bispectrum. We propose an analytic template for the monopole which can be used to fit against data on large scales, extending models used in the recent measurements. Finally, we perform idealised forecasts on σ {sub f} {sub N{sub L}}—the accuracy of the determination of local non-linear parameter f {sub NL}—from measurements of the galaxy bispectrum. Our findings suggest that current surveys can in principle provide f {sub NL} constraints competitive with Planck , and future surveys could improve them further.
Galaxy bispectrum, primordial non-Gaussianity and redshift space distortions
International Nuclear Information System (INIS)
Tellarini, Matteo; Ross, Ashley J.; Wands, David; Tasinato, Gianmassimo
2016-01-01
Measurements of the non-Gaussianity of the primordial density field have the power to considerably improve our understanding of the physics of inflation. Indeed, if we can increase the precision of current measurements by an order of magnitude, a null-detection would rule out many classes of scenarios for generating primordial fluctuations. Large-scale galaxy redshift surveys represent experiments that hold the promise to realise this goal. Thus, we model the galaxy bispectrum and forecast the accuracy with which it will probe the parameter f NL , which represents the degree of primordial local-type non Gaussianity. Specifically, we address the problem of modelling redshift space distortions (RSD) in the tree-level galaxy bispectrum including f NL . We find novel contributions associated with RSD, with the characteristic large scale amplification induced by local-type non-Gaussianity. These RSD effects must be properly accounted for in order to obtain un-biased measurements of f NL from the galaxy bispectrum. We propose an analytic template for the monopole which can be used to fit against data on large scales, extending models used in the recent measurements. Finally, we perform idealised forecasts on σ f NL —the accuracy of the determination of local non-linear parameter f NL —from measurements of the galaxy bispectrum. Our findings suggest that current surveys can in principle provide f NL constraints competitive with Planck , and future surveys could improve them further.
Primordial non-Gaussianity from LAMOST surveys
International Nuclear Information System (INIS)
Gong Yan; Wang Xin; Chen Xuelei; Zheng Zheng
2010-01-01
The primordial non-Gaussianity (PNG) in the matter density perturbation is a very powerful probe of the physics of the very early Universe. The local PNG can induce a distinct scale-dependent bias on the large scale structure distribution of galaxies and quasars, which could be used for constraining it. We study the detection limits of PNG from the surveys of the LAMOST telescope. The cases of the main galaxy survey, the luminous red galaxy (LRG) survey, and the quasar survey of different magnitude limits are considered. We find that the Main1 sample (i.e. the main galaxy survey which is one magnitude deeper than the SDSS main galaxy survey, or r NL are |f NL | NL | NL | is between 50 and 103, depending on the magnitude limit of the survey. With Planck-like priors on cosmological parameters, the quasar survey with g NL | < 43 (2σ). We also discuss the possibility of further tightening the constraint by using the relative bias method proposed by Seljak.
Resource theory of non-Gaussian operations
Zhuang, Quntao; Shor, Peter W.; Shapiro, Jeffrey H.
2018-05-01
Non-Gaussian states and operations are crucial for various continuous-variable quantum information processing tasks. To quantitatively understand non-Gaussianity beyond states, we establish a resource theory for non-Gaussian operations. In our framework, we consider Gaussian operations as free operations, and non-Gaussian operations as resources. We define entanglement-assisted non-Gaussianity generating power and show that it is a monotone that is nonincreasing under the set of free superoperations, i.e., concatenation and tensoring with Gaussian channels. For conditional unitary maps, this monotone can be analytically calculated. As examples, we show that the non-Gaussianity of ideal photon-number subtraction and photon-number addition equal the non-Gaussianity of the single-photon Fock state. Based on our non-Gaussianity monotone, we divide non-Gaussian operations into two classes: (i) the finite non-Gaussianity class, e.g., photon-number subtraction, photon-number addition, and all Gaussian-dilatable non-Gaussian channels; and (ii) the diverging non-Gaussianity class, e.g., the binary phase-shift channel and the Kerr nonlinearity. This classification also implies that not all non-Gaussian channels are exactly Gaussian dilatable. Our resource theory enables a quantitative characterization and a first classification of non-Gaussian operations, paving the way towards the full understanding of non-Gaussianity.
The halo bispectrum in N-body simulations with non-Gaussian initial conditions
Sefusatti, E.; Crocce, M.; Desjacques, V.
2012-10-01
We present measurements of the bispectrum of dark matter haloes in numerical simulations with non-Gaussian initial conditions of local type. We show, in the first place, that the overall effect of primordial non-Gaussianity on the halo bispectrum is larger than on the halo power spectrum when all measurable configurations are taken into account. We then compare our measurements with a tree-level perturbative prediction, finding good agreement at large scales when the constant Gaussian bias parameter, both linear and quadratic, and their constant non-Gaussian corrections are fitted for. The best-fitting values of the Gaussian bias factors and their non-Gaussian, scale-independent corrections are in qualitative agreement with the peak-background split expectations. In particular, we show that the effect of non-Gaussian initial conditions on squeezed configurations is fairly large (up to 30 per cent for fNL = 100 at redshift z = 0.5) and results from contributions of similar amplitude induced by the initial matter bispectrum, scale-dependent bias corrections as well as from non-linear matter bispectrum corrections. We show, in addition, that effects at second order in fNL are irrelevant for the range of values allowed by cosmic microwave background and galaxy power spectrum measurements, at least on the scales probed by our simulations (k > 0.01 h Mpc-1). Finally, we present a Fisher matrix analysis to assess the possibility of constraining primordial non-Gaussianity with future measurements of the galaxy bispectrum. We find that a survey with a volume of about 10 h-3 Gpc3 at mean redshift z ≃ 1 could provide an error on fNL of the order of a few. This shows the relevance of a joint analysis of galaxy power spectrum and bispectrum in future redshift surveys.
Non-Gaussianity from self-ordering scalar fields
International Nuclear Information System (INIS)
Figueroa, Daniel G.; Caldwell, Robert R.; Kamionkowski, Marc
2010-01-01
The Universe may harbor relics of the post-inflationary epoch in the form of a network of self-ordered scalar fields. Such fossils, while consistent with current cosmological data at trace levels, may leave too weak an imprint on the cosmic microwave background and the large-scale distribution of matter to allow for direct detection. The non-Gaussian statistics of the density perturbations induced by these fields, however, permit a direct means to probe for these relics. Here we calculate the bispectrum that arises in models of self-ordered scalar fields. We find a compact analytic expression for the bispectrum, evaluate it numerically, and provide a simple approximation that may be useful for data analysis. The bispectrum is largest for triangles that are aligned (have edges k 1 ≅2k 2 ≅2k 3 ) as opposed to the local-model bispectrum, which peaks for squeezed triangles (k 1 ≅k 2 >>k 3 ), and the equilateral bispectrum, which peaks at k 1 ≅k 2 ≅k 3 . We estimate that this non-Gaussianity should be detectable by the Planck satellite if the contribution from self-ordering scalar fields to primordial perturbations is near the current upper limit.
Revisiting non-Gaussianity from non-attractor inflation models
Cai, Yi-Fu; Chen, Xingang; Namjoo, Mohammad Hossein; Sasaki, Misao; Wang, Dong-Gang; Wang, Ziwei
2018-05-01
Non-attractor inflation is known as the only single field inflationary scenario that can violate non-Gaussianity consistency relation with the Bunch-Davies vacuum state and generate large local non-Gaussianity. However, it is also known that the non-attractor inflation by itself is incomplete and should be followed by a phase of slow-roll attractor. Moreover, there is a transition process between these two phases. In the past literature, this transition was approximated as instant and the evolution of non-Gaussianity in this phase was not fully studied. In this paper, we follow the detailed evolution of the non-Gaussianity through the transition phase into the slow-roll attractor phase, considering different types of transition. We find that the transition process has important effect on the size of the local non-Gaussianity. We first compute the net contribution of the non-Gaussianities at the end of inflation in canonical non-attractor models. If the curvature perturbations keep evolving during the transition—such as in the case of smooth transition or some sharp transition scenarios—the Script O(1) local non-Gaussianity generated in the non-attractor phase can be completely erased by the subsequent evolution, although the consistency relation remains violated. In extremal cases of sharp transition where the super-horizon modes freeze immediately right after the end of the non-attractor phase, the original non-attractor result can be recovered. We also study models with non-canonical kinetic terms, and find that the transition can typically contribute a suppression factor in the squeezed bispectrum, but the final local non-Gaussianity can still be made parametrically large.
First constraints on the running of non-Gaussianity.
Becker, Adam; Huterer, Dragan
2012-09-21
We use data from the Wilkinson Microwave Anisotropy probe temperature maps to constrain a scale-dependent generalization of the popular "local" model for primordial non-Gaussianity. In the model where the parameter f(NL) is allowed to run with scale k, f(NL)(k) = f*(NL) (k/k(piv))(n)(fNL), we constrain the running to be n(f)(NL) = 0.30(-1.2)(+1.9) at 95% confidence, marginalized over the amplitude f*(NL). The constraints depend somewhat on the prior probabilities assigned to the two parameters. In the near future, constraints from a combination of Planck and large-scale structure surveys are expected to improve this limit by about an order of magnitude and usefully constrain classes of inflationary models.
Hunting for primordial non-Gaussianity in the cosmic microwave background
International Nuclear Information System (INIS)
Komatsu, Eiichiro
2010-01-01
Since the first limit on the (local) primordial non-Gaussianity parameter, f NL , was obtained from the Cosmic Background Explorer (COBE) data in 2002, observations of the cosmic microwave background (CMB) have been playing a central role in constraining the amplitudes of various forms of non-Gaussianity in primordial fluctuations. The current 68% limit from the 7-year data of the Wilkinson Microwave Anisotropy Probe (WMAP) is f NL = 32 ± 21, and the Planck satellite is expected to reduce the uncertainty by a factor of 4 in a few years from now. If f NL >> 1 is found by Planck with high statistical significance, all single-field models of inflation would be ruled out. Moreover, if the Planck satellite finds f NL ∼ 30, then it would be able to test a broad class of multi-field models using the 4-point function (trispectrum) test of τ NL ≥ (6f NL /5) 2 . In this paper, we review the methods (optimal estimator), results (WMAP 7-year) and challenges (secondary anisotropy, second-order effect and foreground) of measuring primordial non-Gaussianity from the CMB data, present a science case for the trispectrum and conclude with future prospects.
Loop corrections to primordial non-Gaussianity
Boran, Sibel; Kahya, E. O.
2018-02-01
We discuss quantum gravitational loop effects to observable quantities such as curvature power spectrum and primordial non-Gaussianity of cosmic microwave background (CMB) radiation. We first review the previously shown case where one gets a time dependence for zeta-zeta correlator due to loop corrections. Then we investigate the effect of loop corrections to primordial non-Gaussianity of CMB. We conclude that, even with a single scalar inflaton, one might get a huge value for non-Gaussianity which would exceed the observed value by at least 30 orders of magnitude. Finally we discuss the consequences of this result for scalar driven inflationary models.
Non-Gaussianity from isocurvature perturbations
Energy Technology Data Exchange (ETDEWEB)
Kawasaki, Masahiro; Nakayama, Kazunori; Sekiguchi, Toyokazu; Suyama, Teruaki [Institute for Cosmic Ray Research, University of Tokyo, Kashiwa 277-8582 (Japan); Takahashi, Fuminobu, E-mail: kawasaki@icrr.u-tokyo.ac.jp, E-mail: nakayama@icrr.u-tokyo.ac.jp, E-mail: sekiguti@icrr.u-tokyo.ac.jp, E-mail: suyama@icrr.u-tokyo.ac.jp, E-mail: fuminobu.takahashi@ipmu.jp [Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa 277-8568 (Japan)
2008-11-15
We develop a formalism for studying non-Gaussianity in both curvature and isocurvature perturbations. It is shown that non-Gaussianity in the isocurvature perturbation between dark matter and photons leaves distinct signatures in the cosmic microwave background temperature fluctuations, which may be confirmed in future experiments, or possibly even in the currently available observational data. As an explicit example, we consider the quantum chromodynamics axion and show that it can actually induce sizable non-Gaussianity for the inflationary scale, H{sub inf} = O(10{sup 9}-10{sup 11}) GeV.
Galaxy bias and primordial non-Gaussianity
Energy Technology Data Exchange (ETDEWEB)
Assassi, Valentin; Baumann, Daniel [DAMTP, Cambridge University, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Schmidt, Fabian, E-mail: assassi@ias.edu, E-mail: D.D.Baumann@uva.nl, E-mail: fabians@MPA-Garching.MPG.DE [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85748 Garching (Germany)
2015-12-01
We present a systematic study of galaxy biasing in the presence of primordial non-Gaussianity. For a large class of non-Gaussian initial conditions, we define a general bias expansion and prove that it is closed under renormalization, thereby showing that the basis of operators in the expansion is complete. We then study the effects of primordial non-Gaussianity on the statistics of galaxies. We show that the equivalence principle enforces a relation between the scale-dependent bias in the galaxy power spectrum and that in the dipolar part of the bispectrum. This provides a powerful consistency check to confirm the primordial origin of any observed scale-dependent bias. Finally, we also discuss the imprints of anisotropic non-Gaussianity as motivated by recent studies of higher-spin fields during inflation.
Galaxy bias and primordial non-Gaussianity
International Nuclear Information System (INIS)
Assassi, Valentin; Baumann, Daniel; Schmidt, Fabian
2015-01-01
We present a systematic study of galaxy biasing in the presence of primordial non-Gaussianity. For a large class of non-Gaussian initial conditions, we define a general bias expansion and prove that it is closed under renormalization, thereby showing that the basis of operators in the expansion is complete. We then study the effects of primordial non-Gaussianity on the statistics of galaxies. We show that the equivalence principle enforces a relation between the scale-dependent bias in the galaxy power spectrum and that in the dipolar part of the bispectrum. This provides a powerful consistency check to confirm the primordial origin of any observed scale-dependent bias. Finally, we also discuss the imprints of anisotropic non-Gaussianity as motivated by recent studies of higher-spin fields during inflation
Non-Gaussianity in island cosmology
International Nuclear Information System (INIS)
Piao Yunsong
2009-01-01
In this paper we fully calculate the non-Gaussianity of primordial curvature perturbation of the island universe by using the second order perturbation equation. We find that for the spectral index n s ≅0.96, which is favored by current observations, the non-Gaussianity level f NL seen in an island will generally lie between 30 and 60, which may be tested by the coming observations. In the landscape, the island universe is one of anthropically acceptable cosmological histories. Thus the results obtained in some sense mean the coming observations, especially the measurement of non-Gaussianity, will be significant to clarify how our position in the landscape is populated.
Non-Gaussian bias: insights from discrete density peaks
Desjacques, Vincent; Riotto, Antonio
2013-01-01
Corrections induced by primordial non-Gaussianity to the linear halo bias can be computed from a peak-background split or the widespread local bias model. However, numerical simulations clearly support the prediction of the former, in which the non-Gaussian amplitude is proportional to the linear halo bias. To understand better the reasons behind the failure of standard Lagrangian local bias, in which the halo overdensity is a function of the local mass overdensity only, we explore the effect of a primordial bispectrum on the 2-point correlation of discrete density peaks. We show that the effective local bias expansion to peak clustering vastly simplifies the calculation. We generalize this approach to excursion set peaks and demonstrate that the resulting non-Gaussian amplitude, which is a weighted sum of quadratic bias factors, precisely agrees with the peak-background split expectation, which is a logarithmic derivative of the halo mass function with respect to the normalisation amplitude. We point out tha...
Jimenez, Raul
2009-01-01
The recent weak lensing measurement of the dark matter mass of the high-redshift galaxy cluster XMMUJ2235.3-2557 of (8.5 +- 1.7) x 10^{14} Msun at z=1.4, indicates that, if the cluster is assumed to be the result of the collapse of dark matter in a primordial gaussian field in the standard LCDM model, then its abundance should be 3-10 if the non-Gaussianity parameter f^local_NL is in the range 150-200. This value is comparable to the limit for f_NL obtained by current constraints from the CMB. We conclude that mass determination of high-redshift, massive clusters can offer a complementary probe of primordial non-gaussianity.
The properties of the dark matter halo distribution in non-Gaussian scenarios
International Nuclear Information System (INIS)
Carbone, C.; Branchini, E.; Dolag, K.; Grossi, M.; Iannuzzi, F.; Matarrese, S.; Moscardini, L.; Verde, L.
2009-01-01
The description of halo abundance and clustering for non-Gaussian initial conditions has recently received renewed interest, motivated by the forthcoming large galaxy and cluster surveys, which can potentially detect primordial non-Gaussianity of the local form with a non-Gaussianity parameter |f NL | of order unity. This is particularly exciting because, while the simplest single-field slow-roll models of inflation predict a primordial |f NL | NL of large-scale structures that are expected to be above the predicted detection threshold [C. Carbone, L. Verde, and S. Matarrese, ApJL 684 (2008) L1]. We present tests on N-body simulations of analytical formulae describing the halo abundance and clustering for non-Gaussian initial conditions. In particular, when we calibrate the analytic non-Gaussian mass function of [S. Matarrese, L. Verde, L. and R. Jimenez, ApJL 541 (2000) 10] and [M. LoVerde, A. Miller, S. Shandera and L. Verde, JCAP 04 (2008) 014] and the analytic description of halo clustering for non-Gaussian initial conditions on N-body simulations, we find excellent agreement between the simulations and the analytic predictions if we make the substitutions δ c →δ c x√(q) and δ c →δ c xq where q≅0.75, in the density threshold for gravitational collapse and in the non-Gaussian fractional correction to the halo bias, respectively. We discuss the implications of these corrections on present and forecasted primordial non-Gaussianity constraints. We confirm that the non-Gaussian halo bias offers a robust and highly competitive test of primordial non-Gaussianity.
Large non-Gaussianity from two-component hybrid inflation
International Nuclear Information System (INIS)
Byrnes, Christian T.; Choi, Ki-Young; Hall, Lisa M.H.
2009-01-01
We study the generation of non-Gaussianity in models of hybrid inflation with two inflaton fields, (2-brid inflation). We analyse the region in the parameter and the initial condition space where a large non-Gaussianity may be generated during slow-roll inflation which is generally characterised by a large f NL , τ NL and a small g NL . For certain parameter values we can satisfy τ NL >> f NL 2 . The bispectrum is of the local type but may have a significant scale dependence. We show that the loop corrections to the power spectrum and bispectrum are suppressed during inflation, if one assume that the fields follow a classical background trajectory. We also include the effect of the waterfall field, which can lead to a significant change in the observables after the waterfall field is destabilised, depending on the couplings between the waterfall and inflaton fields
Phase statistics in non-Gaussian scattering
International Nuclear Information System (INIS)
Watson, Stephen M; Jakeman, Eric; Ridley, Kevin D
2006-01-01
Amplitude weighting can improve the accuracy of frequency measurements in signals corrupted by multiplicative speckle noise. When the speckle field constitutes a circular complex Gaussian process, the optimal function of amplitude weighting is provided by the field intensity, corresponding to the intensity-weighted phase derivative statistic. In this paper, we investigate the phase derivative and intensity-weighted phase derivative returned from a two-dimensional random walk, which constitutes a generic scattering model capable of producing both Gaussian and non-Gaussian fluctuations. Analytical results are developed for the correlation properties of the intensity-weighted phase derivative, as well as limiting probability densities of the scattered field. Numerical simulation is used to generate further probability densities and determine optimal weighting criteria from non-Gaussian fields. The results are relevant to frequency retrieval in radiation scattered from random media
Searching for primordial non-Gaussianity in Planck CMB maps using a combined estimator
Energy Technology Data Exchange (ETDEWEB)
Novaes, C.P.; Wuensche, C.A. [Divisão de Astrofísica, Instituto Nacional de Pesquisas Espaciais, Av. dos Astronautas 1758, São José dos Campos 12227-010, SP (Brazil); Bernui, A. [Observatório Nacional, Rua General José Cristino 77, São Cristóvão, 20921-400, Rio de Janeiro, RJ (Brazil); Ferreira, I.S., E-mail: camilapnovaes@gmail.com, E-mail: bernui@on.br, E-mail: ivan@fis.unb.br, E-mail: ca.wuensche@inpe.br [Instituto de Física, Universidade de Brasília, Campus Universitário Darcy Ribeiro, Asa Norte, 70919-970, Brasília, DF (Brazil)
2014-01-01
The extensive search for deviations from Gaussianity in cosmic microwave background radiation (CMB) data is very important due to the information about the very early moments of the universe encoded there. Recent analyses from Planck CMB data do not exclude the presence of non-Gaussianity of small amplitude, although they are consistent with the Gaussian hypothesis. The use of different techniques is essential to provide information about types and amplitudes of non-Gaussianities in the CMB data. In particular, we find interesting to construct an estimator based upon the combination of two powerful statistical tools that appears to be sensitive enough to detect tiny deviations from Gaussianity in CMB maps. This estimator combines the Minkowski functionals with a Neural Network, maximizing a tool widely used to study non-Gaussian signals with a reinforcement of another tool designed to identify patterns in a data set. We test our estimator by analyzing simulated CMB maps contaminated with different amounts of local primordial non-Gaussianity quantified by the dimensionless parameter f{sub NL}. We apply it to these sets of CMB maps and find ∼> 98% of chance of positive detection, even for small intensity local non-Gaussianity like f{sub NL} = 38±18, the current limit from Planck data for large angular scales. Additionally, we test the suitability to distinguish between primary and secondary non-Gaussianities: first we train the Neural Network with two sets, one of nearly Gaussian CMB maps (|f{sub NL}| ≤ 10) but contaminated with realistic inhomogeneous Planck noise (i.e., secondary non-Gaussianity) and the other of non-Gaussian CMB maps, that is, maps endowed with weak primordial non-Gaussianity (28 ≤ f{sub NL} ≤ 48); after that we test an ensemble composed of CMB maps either with one of these non-Gaussian contaminations, and find out that our method successfully classifies ∼ 95% of the tested maps as being CMB maps containing primordial or
Resonant non-Gaussianity with equilateral properties
International Nuclear Information System (INIS)
Gwyn, Rhiannon; Rummel, Markus
2012-11-01
We discuss the effect of superimposing multiple sources of resonant non-Gaussianity, which arise for instance in models of axion inflation. The resulting sum of oscillating shape contributions can be used to ''Fourier synthesize'' different non-oscillating shapes in the bispectrum. As an example we reproduce an approximately equilateral shape from the superposition of O(10) oscillatory contributions with resonant shape. This implies a possible degeneracy between the equilateral-type non-Gaussianity typical of models with non-canonical kinetic terms, such as DBI inflation, and an equilateral-type shape arising from a superposition of resonant-type contributions in theories with canonical kinetic terms. The absence of oscillations in the 2-point function together with the structure of the resonant N-point functions, imply that detection of equilateral non-Gaussianity at a level greater than the PLANCK sensitivity of f NL ∝O(5) will rule out a resonant origin. We comment on the questions arising from possible embeddings of this idea in a string theory setting.
Resonant non-Gaussianity with equilateral properties
Energy Technology Data Exchange (ETDEWEB)
Gwyn, Rhiannon [Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut), Potsdam (Germany); Rummel, Markus [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Westphal, Alexander [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2012-11-15
We discuss the effect of superimposing multiple sources of resonant non-Gaussianity, which arise for instance in models of axion inflation. The resulting sum of oscillating shape contributions can be used to ''Fourier synthesize'' different non-oscillating shapes in the bispectrum. As an example we reproduce an approximately equilateral shape from the superposition of O(10) oscillatory contributions with resonant shape. This implies a possible degeneracy between the equilateral-type non-Gaussianity typical of models with non-canonical kinetic terms, such as DBI inflation, and an equilateral-type shape arising from a superposition of resonant-type contributions in theories with canonical kinetic terms. The absence of oscillations in the 2-point function together with the structure of the resonant N-point functions, imply that detection of equilateral non-Gaussianity at a level greater than the PLANCK sensitivity of f{sub NL} {proportional_to}O(5) will rule out a resonant origin. We comment on the questions arising from possible embeddings of this idea in a string theory setting.
The Matter Bispectrum in N-body Simulations with non-Gaussian Initial Conditions
Sefusatti, Emiliano; Crocce, Martin; Desjacques, Vincent
2010-01-01
We present measurements of the dark matter bispectrum in N-body simulations with non-Gaussian initial conditions of the local kind for a large variety of triangular configurations and compare them with predictions from Eulerian perturbation theory up to one-loop corrections. We find that the effects of primordial non-Gaussianity at large scales, when compared to perturbation theory, are well described by the initial component of the matter bispectrum, linearly extrapolated at the redshift of ...
Non-Gaussianity from Broken Symmetries
Kolb, Edward W; Vallinotto, A; Kolb, Edward W.; Riotto, Antonio; Vallinotto, Alberto
2006-01-01
Recently we studied inflation models in which the inflaton potential is characterized by an underlying approximate global symmetry. In the first work we pointed out that in such a model curvature perturbations are generated after the end of the slow-roll phase of inflation. In this work we develop further the observational implications of the model and compute the degree of non-Gaussianity predicted in the scenario. We find that the corresponding nonlinearity parameter, $f_{NL}$, can be as large as 10^2.
Integration of non-Gaussian fields
DEFF Research Database (Denmark)
Ditlevsen, Ove Dalager; Mohr, Gunnar; Hoffmeyer, Pernille
1996-01-01
The limitations of the validity of the central limit theorem argument as applied to definite integrals of non-Gaussian random fields are empirically explored by way of examples. The purpose is to investigate in specific cases whether the asymptotic convergence to the Gaussian distribution is fast....... and Randrup-Thomsen, S. Reliability of silo ring under lognormal stochastic pressure using stochastic interpolation. Proc. IUTAM Symp., Probabilistic Structural Mechanics: Advances in Structural Reliability Methods, San Antonio, TX, USA, June 1993 (eds.: P. D. Spanos & Y.-T. Wu) pp. 134-162. Springer, Berlin...
CMB constraints on running non-Gaussianity
Oppizzi, Filippo; Liguori, Michele; Renzi, Alessandro; Arroja, Frederico; Bartolo, Nicola
2017-01-01
We develop a complete set of tools for CMB forecasting, simulation and estimation of primordial running bispectra, arising from a variety of curvaton and single-field (DBI) models of Inflation. We validate our pipeline using mock CMB running non-Gaussianity realizations and test it on real data by obtaining experimental constraints on the $f_{\\rm NL}$ running spectral index, $n_{\\rm NG}$, using WMAP 9-year data. Our final bounds (68\\% C.L.) read $-0.3< n_{\\rm NG}
Multi-brid inflation and non-gaussianity
International Nuclear Information System (INIS)
Sasaki, Misao
2008-01-01
We consider a class of multi-component hybrid inflation models whose evolution may be analytically solved under the slow-roll approximation. We call it multi-brid inflation (or n-brid inflation where n stands for the number of inflaton fields). As an explicit example, we consider a two-brid inflation model, in which the inflaton potentials are of exponential type and a waterfall field that terminates inflation has the standard quartic potential with two minima. Using the δN formalism, we derive an expression for the curvature perturbation valid to full nonlinear order. Then we give an explicit expression for the curvature perturbation to second order in the inflaton perturbation. We find that the final from of the curvature perturbation depends crucially on how the inflation ends. Using this expression, we present closed analytical expressions for the spectrum of the curvature perturbation Ps(k), the spectral index n s , the tensor to scalar ratio r, and the non-Gaussian parameter f NL local , in terms of the model parameters. We find that a wide range of the parameter space (n s , r, f NL local ) can be covered by varying the model parameters within a physically reasonable range. In particular, for plausible values of the model parameters, we may have a large non-Gaussianity f NL local ∼10-100. This is in sharp contrast to the case of single-field hybrid inflation in which these parameters are tightly constrained. (author)
Non-gaussianity versus nonlinearity of cosmological perturbations.
Verde, L
2001-06-01
Following the discovery of the cosmic microwave background, the hot big-bang model has become the standard cosmological model. In this theory, small primordial fluctuations are subsequently amplified by gravity to form the large-scale structure seen today. Different theories for unified models of particle physics, lead to different predictions for the statistical properties of the primordial fluctuations, that can be divided in two classes: gaussian and non-gaussian. Convincing evidence against or for gaussian initial conditions would rule out many scenarios and point us toward a physical theory for the origin of structures. The statistical distribution of cosmological perturbations, as we observe them, can deviate from the gaussian distribution in several different ways. Even if perturbations start off gaussian, nonlinear gravitational evolution can introduce non-gaussian features. Additionally, our knowledge of the Universe comes principally from the study of luminous material such as galaxies, but galaxies might not be faithful tracers of the underlying mass distribution. The relationship between fluctuations in the mass and in the galaxies distribution (bias), is often assumed to be local, but could well be nonlinear. Moreover, galaxy catalogues use the redshift as third spatial coordinate: the resulting redshift-space map of the galaxy distribution is nonlinearly distorted by peculiar velocities. Nonlinear gravitational evolution, biasing, and redshift-space distortion introduce non-gaussianity, even in an initially gaussian fluctuation field. I investigate the statistical tools that allow us, in principle, to disentangle the above different effects, and the observational datasets we require to do so in practice.
Planck 2013 Results. XXIV. Constraints on primordial non-Gaussianity
Ade, P.A.R.; Armitage-Caplan, C.; Arnaud, M.; Ashdown, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Banday, A.J.; Barreiro, R.B.; Bartlett, J.G.; Bartolo, N.; Battaner, E.; Benabed, K.; Benoit, A.; Benoit-Levy, A.; Bernard, J.P.; Bersanelli, M.; Bielewicz, P.; Bobin, J.; Bock, J.J.; Bonaldi, A.; Bonavera, L.; Bond, J.R.; Borrill, J.; Bouchet, F.R.; Bridges, M.; Bucher, M.; Burigana, C.; Butler, R.C.; Cardoso, J.F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chiang, L.Y.; Chiang, H.C.; Christensen, P.R.; Church, S.; Clements, D.L.; Colombi, S.; Colombo, L.P.L.; Couchot, F.; Coulais, A.; Crill, B.P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R.D.; Davis, R.J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Delouis, J.M.; Desert, F.X.; Diego, J.M.; Dole, H.; Donzelli, S.; Dore, O.; Douspis, M.; Ducout, A.; Dunkley, J.; Dupac, X.; Efstathiou, G.; Elsner, F.; Ensslin, T.A.; Eriksen, H.K.; Fergusson, J.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Galeotta, S.; Ganga, K.; Giard, M.; Giraud-Heraud, Y.; Gonzalez-Nuevo, J.; Gorski, K.M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Hansen, F.K.; Hanson, D.; Harrison, D.; Heavens, A.; Henrot-Versille, S.; Hernandez-Monteagudo, C.; Herranz, D.; Hildebrandt, S.R.; Hivon, E.; Hobson, M.; Holmes, W.A.; Hornstrup, A.; Hovest, W.; Huffenberger, K.M.; Jaffe, T.R.; Jaffe, A.H.; Jones, W.C.; Juvela, M.; Keihanen, E.; Keskitalo, R.; Kisner, T.S.; Knoche, J.; Knox, L.; Kunz, M.; Kurki-Suonio, H.; Lacasa, F.; Lagache, G.; Lahteenmaki, A.; Lamarre, J.M.; Lasenby, A.; Laureijs, R.J.; Lawrence, C.R.; Leahy, J.P.; Leonardi, R.; Lesgourgues, J.; Lewis, A.; Liguori, M.; Lilje, P.B.; Linden-Vornle, M.; Lopez-Caniego, M.; Lubin, P.M.; Macias-Perez, J.F.; Maffei, B.; Maino, D.; Mandolesi, N.; Mangilli, A.; Marinucci, D.; Maris, M.; Marshall, D.J.; Martin, P.G.; Martinez-Gonzalez, E.; Masi, S.; Matarrese, S.; Matthai, F.; Mazzotta, P.; Meinhold, P.R.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschenes, M.A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Moss, A.; Munshi, D.; Naselsky, P.; Natoli, P.; Netterfield, C.B.; Norgaard-Nielsen, H.U.; Noviello, F.; Novikov, D.; Novikov, I.; Osborne, S.; Oxborrow, C.A.; Paci, F.; Pagano, L.; Pajot, F.; Paoletti, D.; Pasian, F.; Patanchon, G.; Peiris, H.V.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Poutanen, T.; Pratt, G.W.; Prezeau, G.; Prunet, S.; Puget, J.L.; Rachen, J.P.; Racine, B.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Renzi, A.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rubino-Martin, J.A.; Rusholme, B.; Sandri, M.; Santos, D.; Savini, G.; Scott, D.; Seiffert, M.D.; Shellard, E.P.S.; Smith, K.; Spencer, L.D.; Starck, J.L.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sunyaev, R.; Sureau, F.; Sutton, D.; Suur-Uski, A.S.; Sygnet, J.F.; Tauber, J.A.; Tavagnacco, D.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Tuovinen, J.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Varis, J.; Vielva, P.; Villa, F.; Vittorio, N.; Wade, L.A.; Wandelt, B.D.; White, M.; White, S.D.M.; Yvon, D.; Zacchei, A.; Zonca, A.
2014-01-01
The Planck nominal mission cosmic microwave background (CMB) maps yield unprecedented constraints on primordial non-Gaussianity (NG). Using three optimal bispectrum estimators, separable template-fitting (KSW), binned, and modal, we obtain consistent values for the primordial local, equilateral, and orthogonal bispectrum amplitudes, quoting as our final result fNL^local= 2.7+/-5.8, fNL^equil= -42+/-75, and fNL^ortho= -25+\\-39 (68% CL statistical). NG is detected in the data; using skew-C_l statistics we find a nonzero bispectrum from residual point sources, and the ISW-lensing bispectrum at a level expected in the LambdaCDM scenario. The results are based on comprehensive cross-validation of these estimators on Gaussian and non-Gaussian simulations, are stable across component separation techniques, pass an extensive suite of tests, and are confirmed by skew-C_l, wavelet bispectrum and Minkowski functional estimators. Beyond estimates of individual shape amplitudes, we present model-independent, 3-dimensional...
Interconversion of pure Gaussian states requiring non-Gaussian operations
Jabbour, Michael G.; García-Patrón, Raúl; Cerf, Nicolas J.
2015-01-01
We analyze the conditions under which local operations and classical communication enable entanglement transformations between bipartite pure Gaussian states. A set of necessary and sufficient conditions had been found [G. Giedke et al., Quant. Inf. Comput. 3, 211 (2003)] for the interconversion between such states that is restricted to Gaussian local operations and classical communication. Here, we exploit majorization theory in order to derive more general (sufficient) conditions for the interconversion between bipartite pure Gaussian states that goes beyond Gaussian local operations. While our technique is applicable to an arbitrary number of modes for each party, it allows us to exhibit surprisingly simple examples of 2 ×2 Gaussian states that necessarily require non-Gaussian local operations to be transformed into each other.
Primordial Non-Gaussianity in the Large-Scale Structure of the Universe
Directory of Open Access Journals (Sweden)
Vincent Desjacques
2010-01-01
generated the cosmological fluctuations observed today. Any detection of significant non-Gaussianity would thus have profound implications for our understanding of cosmic structure formation. The large-scale mass distribution in the Universe is a sensitive probe of the nature of initial conditions. Recent theoretical progress together with rapid developments in observational techniques will enable us to critically confront predictions of inflationary scenarios and set constraints as competitive as those from the Cosmic Microwave Background. In this paper, we review past and current efforts in the search for primordial non-Gaussianity in the large-scale structure of the Universe.
Model-independent test for scale-dependent non-Gaussianities in the cosmic microwave background.
Räth, C; Morfill, G E; Rossmanith, G; Banday, A J; Górski, K M
2009-04-03
We present a model-independent method to test for scale-dependent non-Gaussianities in combination with scaling indices as test statistics. Therefore, surrogate data sets are generated, in which the power spectrum of the original data is preserved, while the higher order correlations are partly randomized by applying a scale-dependent shuffling procedure to the Fourier phases. We apply this method to the Wilkinson Microwave Anisotropy Probe data of the cosmic microwave background and find signatures for non-Gaussianities on large scales. Further tests are required to elucidate the origin of the detected anomalies.
Linear velocity fields in non-Gaussian models for large-scale structure
Scherrer, Robert J.
1992-01-01
Linear velocity fields in two types of physically motivated non-Gaussian models are examined for large-scale structure: seed models, in which the density field is a convolution of a density profile with a distribution of points, and local non-Gaussian fields, derived from a local nonlinear transformation on a Gaussian field. The distribution of a single component of the velocity is derived for seed models with randomly distributed seeds, and these results are applied to the seeded hot dark matter model and the global texture model with cold dark matter. An expression for the distribution of a single component of the velocity in arbitrary local non-Gaussian models is given, and these results are applied to such fields with chi-squared and lognormal distributions. It is shown that all seed models with randomly distributed seeds and all local non-Guassian models have single-component velocity distributions with positive kurtosis.
Image reconstruction under non-Gaussian noise
DEFF Research Database (Denmark)
Sciacchitano, Federica
During acquisition and transmission, images are often blurred and corrupted by noise. One of the fundamental tasks of image processing is to reconstruct the clean image from a degraded version. The process of recovering the original image from the data is an example of inverse problem. Due...... to the ill-posedness of the problem, the simple inversion of the degradation model does not give any good reconstructions. Therefore, to deal with the ill-posedness it is necessary to use some prior information on the solution or the model and the Bayesian approach. Additive Gaussian noise has been......D thesis intends to solve some of the many open questions for image restoration under non-Gaussian noise. The two main kinds of noise studied in this PhD project are the impulse noise and the Cauchy noise. Impulse noise is due to for instance the malfunctioning pixel elements in the camera sensors, errors...
Multipoint propagators for non-Gaussian initial conditions
International Nuclear Information System (INIS)
Bernardeau, Francis; Sefusatti, Emiliano; Crocce, Martin
2010-01-01
We show here how renormalized perturbation theory calculations applied to the quasilinear growth of the large-scale structure can be carried on in presence of primordial non-Gaussian (PNG) initial conditions. It is explicitly demonstrated that the series reordering scheme proposed in Bernardeau, Crocce, and Scoccimarro [Phys. Rev. D 78, 103521 (2008)] is preserved for non-Gaussian initial conditions. This scheme applies to the power spectrum and higher-order spectra and is based on a reorganization of the contributing terms into the sum of products of multipoint propagators. In case of PNG, new contributing terms appear, the importance of which is discussed in the context of current PNG models. The properties of the building blocks of such resummation schemes, the multipoint propagators, are then investigated. It is first remarked that their expressions are left unchanged at one-loop order irrespective of statistical properties of the initial field. We furthermore show that the high-momentum limit of each of these propagators can be explicitly computed even for arbitrary initial conditions. They are found to be damped by an exponential cutoff whose expression is directly related to the moment generating function of the one-dimensional displacement field. This extends what had been established for multipoint propagators for Gaussian initial conditions. Numerical forms of the cutoff are shown for the so-called local model of PNG.
Multi-variate joint PDF for non-Gaussianities: exact formulation and generic approximations
Verde, Licia; Heavens, Alan F; Jimenez, Raul; Matarrese, Sabino
2013-01-01
We provide an exact expression for the multi-variate joint probability distribution function of non-Gaussian fields primordially arising from local transformations of a Gaussian field. This kind of non-Gaussianity is generated in many models of inflation. We apply our expression to the non- Gaussianity estimation from Cosmic Microwave Background maps and the halo mass function where we obtain analytical expressions. We also provide analytic approximations and their range of validity. For the Cosmic Microwave Background we give a fast way to compute the PDF which is valid up to 7{\\sigma} for fNL values (both true and sampled) not ruled out by current observations, which consists of expressing the PDF as a combination of bispectrum and trispectrum of the temperature maps. The resulting expression is valid for any kind of non-Gaussianity and is not limited to the local type. The above results may serve as the basis for a fully Bayesian analysis of the non-Gaussianity parameter.
Non-Gaussian conductivity fluctuations in semiconductors
International Nuclear Information System (INIS)
Melkonyan, S.V.
2010-01-01
A theoretical study is presented on the statistical properties of conductivity fluctuations caused by concentration and mobility fluctuations of the current carriers. It is established that mobility fluctuations result from random deviations in the thermal equilibrium distribution of the carriers. It is shown that mobility fluctuations have generation-recombination and shot components which do not satisfy the requirements of the central limit theorem, in contrast to the current carrier's concentration fluctuation and intraband component of the mobility fluctuation. It is shown that in general the mobility fluctuation consist of thermal (or intraband) Gaussian and non-thermal (or generation-recombination, shot, etc.) non-Gaussian components. The analyses of theoretical results and experimental data from literature show that the statistical properties of mobility fluctuation and of 1/f-noise fully coincide. The deviation from Gaussian statistics of the mobility or 1/f fluctuations goes hand in hand with the magnitude of non-thermal noise (generation-recombination, shot, burst, pulse noises, etc.).
Lifting primordial non-Gaussianity above the noise
International Nuclear Information System (INIS)
Welling, Yvette; Woude, Drian van der; Pajer, Enrico
2016-01-01
Primordial non-Gaussianity (PNG) in Large Scale Structures is obfuscated by the many additional sources of non-linearity. Within the Effective Field Theory approach to Standard Perturbation Theory, we show that matter non-linearities in the bispectrum can be modeled sufficiently well to strengthen current bounds with near future surveys, such as Euclid. We find that the EFT corrections are crucial to this improvement in sensitivity. Yet, our understanding of non-linearities is still insufficient to reach important theoretical benchmarks for equilateral PNG, while, for local PNG, our forecast is more optimistic. We consistently account for the theoretical error intrinsic to the perturbative approach and discuss the details of its implementation in Fisher forecasts.
A model of non-Gaussian diffusion in heterogeneous media
Lanoiselée, Yann; Grebenkov, Denis S.
2018-04-01
Recent progress in single-particle tracking has shown evidence of the non-Gaussian distribution of displacements in living cells, both near the cellular membrane and inside the cytoskeleton. Similar behavior has also been observed in granular materials, turbulent flows, gels and colloidal suspensions, suggesting that this is a general feature of diffusion in complex media. A possible interpretation of this phenomenon is that a tracer explores a medium with spatio-temporal fluctuations which result in local changes of diffusivity. We propose and investigate an ergodic, easily interpretable model, which implements the concept of diffusing diffusivity. Depending on the parameters, the distribution of displacements can be either flat or peaked at small displacements with an exponential tail at large displacements. We show that the distribution converges slowly to a Gaussian one. We calculate statistical properties, derive the asymptotic behavior and discuss some implications and extensions.
Sasaki, Misao; Wands, David
2010-06-01
In recent years there has been a resurgence of interest in the study of non-linear perturbations of cosmological models. This has been the result of both theoretical developments and observational advances. New theoretical challenges arise at second and higher order due to mode coupling and the need to develop new gauge-invariant variables beyond first order. In particular, non-linear interactions lead to deviations from a Gaussian distribution of primordial perturbations even if initial vacuum fluctuations are exactly Gaussian. These non-Gaussianities provide an important probe of models for the origin of structure in the very early universe. We now have a detailed picture of the primordial distribution of matter from surveys of the cosmic microwave background, notably NASA's WMAP satellite. The situation will continue to improve with future data from the ESA Planck satellite launched in 2009. To fully exploit these data cosmologists need to extend non-linear cosmological perturbation theory beyond the linear theory that has previously been sufficient on cosmological scales. Another recent development has been the realization that large-scale structure, revealed in high-redshift galaxy surveys, could also be sensitive to non-linearities in the primordial curvature perturbation. This focus section brings together a collection of invited papers which explore several topical issues in this subject. We hope it will be of interest to theoretical physicists and astrophysicists alike interested in understanding and interpreting recent developments in cosmological perturbation theory and models of the early universe. Of course it is only an incomplete snapshot of a rapidly developing field and we hope the reader will be inspired to read further work on the subject and, perhaps, fill in some of the missing pieces. This focus section is dedicated to the memory of Lev Kofman (1957-2009), an enthusiastic pioneer of inflationary cosmology and non-Gaussian perturbations.
Non-Gaussianities in multifield DBI inflation with a waterfall phase transition
Kidani, Taichi; Koyama, Kazuya; Mizuno, Shuntaro
2012-10-01
We study multifield Dirac-Born-Infeld (DBI) inflation models with a waterfall phase transition. This transition happens for a D3 brane moving in the warped conifold if there is an instability along angular directions. The transition converts the angular perturbations into the curvature perturbation. Thanks to this conversion, multifield models can evade the stringent constraints that strongly disfavor single field ultraviolet (UV) DBI inflation models in string theory. We explicitly demonstrate that our model satisfies current observational constraints on the spectral index and equilateral non-Gaussianity as well as the bound on the tensor to scalar ratio imposed in string theory models. In addition, we show that large local type non-Gaussianity is generated together with equilateral non-Gaussianity in this model.
Relativistic effects and primordial non-Gaussianity in the galaxy bias
International Nuclear Information System (INIS)
Bartolo, Nicola; Matarrese, Sabino; Riotto, Antonio
2011-01-01
When dealing with observables, one needs to generalize the bias relation between the observed galaxy fluctuation field to the underlying matter distribution in a gauge-invariant way. We provide such relation at second-order in perturbation theory adopting the local Eulerian bias model and starting from the observationally motivated uniform-redshift gauge. Our computation includes the presence of primordial non-Gaussianity. We show that large scale-dependent relativistic effects in the Eulerian bias arise independently from the presence of some primordial non-Gaussianity. Furthermore, the Eulerian bias inherits from the primordial non-Gaussianity not only a scale-dependence, but also a modulation with the angle of observation when sources with different biases are correlated
IMPROVED SIMULATION OF NON-GAUSSIAN TEMPERATURE AND POLARIZATION COSMIC MICROWAVE BACKGROUND MAPS
International Nuclear Information System (INIS)
Elsner, Franz; Wandelt, Benjamin D.
2009-01-01
We describe an algorithm to generate temperature and polarization maps of the cosmic microwave background (CMB) radiation containing non-Gaussianity of arbitrary local type. We apply an optimized quadrature scheme that allows us to predict and control integration accuracy, speed up the calculations, and reduce memory consumption by an order of magnitude. We generate 1000 non-Gaussian CMB temperature and polarization maps up to a multipole moment of l max = 1024. We validate the method and code using the power spectrum and the fast cubic (bispectrum) estimator and find consistent results. The simulations are provided to the community.
Methods to characterize non-Gaussian noise in TAMA
International Nuclear Information System (INIS)
Ando, Masaki; Arai, K; Takahashi, R; Tatsumi, D; Beyersdorf, P; Kawamura, S; Miyoki, S; Mio, N; Moriwaki, S; Numata, K; Kanda, N; Aso, Y; Fujimoto, M-K; Tsubono, K; Kuroda, K
2003-01-01
We present a data characterization method for the main output signal of the interferometric gravitational-wave detector, in particular targeting at effective detection of burst gravitational waves from stellar core collapse. The time scale of non-Gaussian events is evaluated in this method, and events with longer time scale than real signals are rejected as non-Gaussian noises. As a result of data analysis using 1000 h of real data with the interferometric gravitational-wave detector TAMA300, the false-alarm rate was improved 10 3 times with this non-Gaussian noise evaluation and rejection method
International Nuclear Information System (INIS)
Tsuchida, Takahiro; Kimura, Koji
2016-01-01
Equivalent non-Gaussian excitation method is proposed to obtain the response moments up to the 4th order of dynamic systems under non-Gaussian random excitation. The non-Gaussian excitation is prescribed by the probability density and the power spectrum, and is described by an Ito stochastic differential equation. Generally, moment equations for the response, which are derived from the governing equations for the excitation and the system, are not closed due to the nonlinearity of the diffusion coefficient in the equation for the excitation even though the system is linear. In the equivalent non-Gaussian excitation method, the diffusion coefficient is replaced with the equivalent diffusion coefficient approximately to obtain a closed set of the moment equations. The square of the equivalent diffusion coefficient is expressed by a quadratic polynomial. In numerical examples, a linear system subjected to nonGaussian excitations with bimodal and Rayleigh distributions is analyzed by using the present method. The results show that the method yields the variance, skewness and kurtosis of the response with high accuracy for non-Gaussian excitation with the widely different probability densities and bandwidth. The statistical moments of the equivalent non-Gaussian excitation are also investigated to describe the feature of the method. (paper)
Planck 2015 results. XVII. Constraints on primordial non-Gaussianity
Ade, P.A.R.; Arnaud, M.; Arroja, F.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Ballardini, M.; Banday, A.J.; Barreiro, R.B.; Bartolo, N.; Basak, S.; Battaner, E.; Benabed, K.; Benoît, A.; Benoit-Lévy, A.; Bernard, J.P.; Bersanelli, M.; Bielewicz, P.; Bock, J.J.; Bonaldi, A.; Bonavera, L.; Bond, J.R.; Borrill, J.; Bouchet, F.R.; Boulanger, F.; Bucher, M.; Burigana, C.; Butler, R.C.; Calabrese, E.; Cardoso, J.F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chiang, H.C.; Christensen, P.R.; Church, S.; Clements, D.L.; Colombi, S.; Colombo, L.P.L.; Combet, C.; Couchot, F.; Coulais, A.; Crill, B.P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R.D.; Davis, R.J.; de Bernardis, P.; De Rosa, A.; De Zotti, G.; Delabrouille, J.; Désert, F.X.; Diego, J.M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Ducout, A.; Dupac, X.; Efstathiou, G.; Elsner, F.; Enßlin, T.A.; Eriksen, H.K.; Fergusson, J.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A.A.; Franceschi, E.; Frejsel, A.; Galeotta, S.; Galli, S.; Ganga, K.; Gauthier, C.; Ghosh, T.; Giard, M.; Giraud-Héraud, Y.; Gjerløw, E.; González-Nuevo, J.; Górski, K.M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J.E.; Hamann, J.; Hansen, F.K.; Hanson, D.; Harrison, D.L.; Heavens, A.; Helou, G.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S.R.; Hivon, E.; Hobson, M.; Holmes, W.A.; Hornstrup, A.; Hovest, W.; Huang, Z.; Huffenberger, K.M.; Hurier, G.; Jaffe, A.H.; Jaffe, T.R.; Jones, W.C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kim, J.; Kisner, T.S.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lacasa, F.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.M.; Lasenby, A.; Lattanzi, M.; Lawrence, C.R.; Leonardi, R.; Lesgourgues, J.; Levrier, F.; Lewis, A.; Liguori, M.; Lilje, P.B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P.M.; Macías-Pérez, J.F.; Maggio, G.; Maino, D.; Mandolesi, N.; Mangilli, A.; Marinucci, D.; Maris, M.; Martin, P.G.; Martínez-González, E.; Masi, S.; Matarrese, S.; McGehee, P.; Meinhold, P.R.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Moss, A.; Münchmeyer, M.; Munshi, D.; Murphy, J.A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C.B.; Nørgaard-Nielsen, H.U.; Noviello, F.; Novikov, D.; Novikov, I.; Oxborrow, C.A.; Paci, F.; Pagano, L.; Pajot, F.; Paoletti, D.; Pasian, F.; Patanchon, G.; Peiris, H.V.; Perdereau, O.; Perotto, L.; Perrotta, F.; Pettorino, V.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Popa, L.; Pratt, G.W.; Prézeau, G.; Prunet, S.; Puget, J.L.; Rachen, J.P.; Racine, B.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Renzi, A.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rossetti, M.; Roudier, G.; Rubiño-Martín, J.A.; Rusholme, B.; Sandri, M.; Santos, D.; Savelainen, M.; Savini, G.; Scott, D.; Seiffert, M.D.; Shellard, E.P.S.; Shiraishi, M.; Smith, K.; Spencer, L.D.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sunyaev, R.; Sutter, P.; Sutton, D.; Suur-Uski, A.S.; Sygnet, J.F.; Tauber, J.A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Troja, A.; Tucci, M.; Tuovinen, J.; Valenziano, L.; Valiviita, J.; van Tent, B.; Vielva, P.; Villa, F.; Wade, L.A.; Wandelt, B.D.; Wehus, I.K.; Yvon, D.; Zacchei, A.; Zonca, A.
2016-01-01
The Planck full mission cosmic microwave background(CMB) temperature and E-mode polarization maps are analysed to obtain constraints on primordial non-Gaussianity(NG). Using three classes of optimal bispectrum estimators - separable template-fitting (KSW), binned, and modal - we obtain consistent values for the local, equilateral, and orthogonal bispectrum amplitudes, quoting as our final result from temperature alone fNL^local=2.5+\\-5.7, fNL^equil=-16+\\-70 and fNL^ortho=-34+\\-33(68%CL). Combining temperature and polarization data we obtain fNL^local=0.8+\\-5.0, fNL^equil=-4+\\-43 and fNL^ortho=-26+\\-21 (68%CL). The results are based on cross-validation of these estimators on simulations, are stable across component separation techniques, pass an extensive suite of tests, and are consistent with Minkowski functionals based measurements. The effect of time-domain de-glitching systematics on the bispectrum is negligible. In spite of these test outcomes we conservatively label the results including polarization da...
Non-Gaussianities due to relativistic corrections to the observed galaxy bispectrum
International Nuclear Information System (INIS)
Dio, E. Di; Perrier, H.; Durrer, R.; Dizgah, A. Moradinezhad; Riotto, A.; Marozzi, G.; Noreña, J.
2017-01-01
High-precision constraints on primordial non-Gaussianity (PNG) will significantly improve our understanding of the physics of the early universe. Among all the subtleties in using large scale structure observables to constrain PNG, accounting for relativistic corrections to the clustering statistics is particularly important for the upcoming galaxy surveys covering progressively larger fraction of the sky. We focus on relativistic projection effects due to the fact that we observe the galaxies through the light that reaches the telescope on perturbed geodesics. These projection effects can give rise to an effective f NL that can be misinterpreted as the primordial non-Gaussianity signal and hence is a systematic to be carefully computed and accounted for in modelling of the bispectrum. We develop the technique to properly account for relativistic effects in terms of purely observable quantities, namely angles and redshifts. We give some examples by applying this approach to a subset of the contributions to the tree-level bispectrum of the observed galaxy number counts calculated within perturbation theory and estimate the corresponding non-Gaussianity parameter, f NL , for the local, equilateral and orthogonal shapes. For the local shape, we also compute the local non-Gaussianity resulting from terms obtained using the consistency relation for observed number counts. Our goal here is not to give a precise estimate of f NL for each shape but rather we aim to provide a scheme to compute the non-Gaussian contamination due to relativistic projection effects. For the terms considered in this work, we obtain contamination of f NL loc ∼ O(1).
Non-Gaussianities due to relativistic corrections to the observed galaxy bispectrum
Energy Technology Data Exchange (ETDEWEB)
Dio, E. Di [INAF—Osservatorio Astronomico di Trieste, Via G.B. Tiepolo 11, Trieste, I-34143 Italy (Italy); Perrier, H.; Durrer, R.; Dizgah, A. Moradinezhad; Riotto, A. [University of Geneva, Department of Theoretical Physics and Center for Astroparticle Physics (CAP), 24 quai E. Ansermet, Geneva 4, CH-1211 Switzerland (Switzerland); Marozzi, G. [Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150, Urca, Rio de Janeiro, CEP 22290-180 Brazil (Brazil); Noreña, J., E-mail: Enea.DiDio@oats.inaf.it, E-mail: Hideki.Perrier@unige.ch, E-mail: Ruth.Durrer@unige.ch, E-mail: Marozzi@cbpf.br, E-mail: amoradinejad@physics.harvard.edu, E-mail: jorge.norena@pucv.cl, E-mail: Antonio.Riotto@unige.ch [Instituto de Física, Pontificia Universidad Católica de Valparaíso, Casilla, Valparaíso, 4059 Chile (Chile)
2017-03-01
High-precision constraints on primordial non-Gaussianity (PNG) will significantly improve our understanding of the physics of the early universe. Among all the subtleties in using large scale structure observables to constrain PNG, accounting for relativistic corrections to the clustering statistics is particularly important for the upcoming galaxy surveys covering progressively larger fraction of the sky. We focus on relativistic projection effects due to the fact that we observe the galaxies through the light that reaches the telescope on perturbed geodesics. These projection effects can give rise to an effective f {sub NL} that can be misinterpreted as the primordial non-Gaussianity signal and hence is a systematic to be carefully computed and accounted for in modelling of the bispectrum. We develop the technique to properly account for relativistic effects in terms of purely observable quantities, namely angles and redshifts. We give some examples by applying this approach to a subset of the contributions to the tree-level bispectrum of the observed galaxy number counts calculated within perturbation theory and estimate the corresponding non-Gaussianity parameter, f {sub NL}, for the local, equilateral and orthogonal shapes. For the local shape, we also compute the local non-Gaussianity resulting from terms obtained using the consistency relation for observed number counts. Our goal here is not to give a precise estimate of f {sub NL} for each shape but rather we aim to provide a scheme to compute the non-Gaussian contamination due to relativistic projection effects. For the terms considered in this work, we obtain contamination of f {sub NL}{sup loc} ∼ O(1).
Non-Gaussianity from inflation: theory and observations
Bartolo, N.; Komatsu, E.; Matarrese, S.; Riotto, A.
2004-11-01
This is a review of models of inflation and of their predictions for the primordial non-Gaussianity in the density perturbations which are thought to be at the origin of structures in the Universe. Non-Gaussianity emerges as a key observable to discriminate among competing scenarios for the generation of cosmological perturbations and is one of the primary targets of present and future Cosmic Microwave Background satellite missions. We give a detailed presentation of the state-of-the-art of the subject of non-Gaussianity, both from the theoretical and the observational point of view, and provide all the tools necessary to compute at second order in perturbation theory the level of non-Gaussianity in any model of cosmological perturbations. We discuss the new wave of models of inflation, which are firmly rooted in modern particle physics theory and predict a significant amount of non-Gaussianity. The review is addressed to both astrophysicists and particle physicists and contains useful tables which summarize the theoretical and observational results regarding non-Gaussianity.
International Nuclear Information System (INIS)
Tsuchida, Takahiro; Kimura, Koji
2015-01-01
Equivalent non-Gaussian excitation method is proposed to obtain the moments up to the fourth order of the response of systems under non-Gaussian random excitation. The excitation is prescribed by the probability density and power spectrum. Moment equations for the response can be derived from the stochastic differential equations for the excitation and the system. However, the moment equations are not closed due to the nonlinearity of the diffusion coefficient in the equation for the excitation. In the proposed method, the diffusion coefficient is replaced with the equivalent diffusion coefficient approximately to obtain a closed set of the moment equations. The square of the equivalent diffusion coefficient is expressed by the second-order polynomial. In order to demonstrate the validity of the method, a linear system to non-Gaussian excitation with generalized Gaussian distribution is analyzed. The results show the method is applicable to non-Gaussian excitation with the widely different kurtosis and bandwidth. (author)
Constraints on Primordial Non-Gaussianity from 800 000 Photometric Quasars.
Leistedt, Boris; Peiris, Hiranya V; Roth, Nina
2014-11-28
We derive robust constraints on primordial non-Gaussianity (PNG) using the clustering of 800 000 photometric quasars from the Sloan Digital Sky Survey in the redshift range 0.5quasar halo bias at the largest scales, while discarding as little as possible of the data. The standard local-type PNG parameters f_{NL} and g_{NL} both imprint a k^{-2} scale-dependent effect in the bias. Constraining these individually, we obtain -49quasar clustering to the underlying dark matter. These are the strongest constraints obtained to date on PNG using a single population of large-scale structure tracers, and are already at the level of pre-Planck constraints from the cosmic microwave background. A conservative forecast for a Large Synoptic Survey Telescope (LSST)-like survey incorporating mode projection yields σ(f_{NL})∼5-competitive with the Planck result-highlighting the power of upcoming large scale structure surveys to probe the initial conditions of the Universe.
Consistency relations for sharp inflationary non-Gaussian features
Energy Technology Data Exchange (ETDEWEB)
Mooij, Sander; Palma, Gonzalo A.; Panotopoulos, Grigoris [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Blanco Encalada 2008, Santiago (Chile); Soto, Alex, E-mail: sander.mooij@ing.uchile.cl, E-mail: gpalmaquilod@ing.uchile.cl, E-mail: gpanotop@ing.uchile.cl, E-mail: gatogeno@gmail.com [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Ñuñoa, Santiago (Chile)
2016-09-01
If cosmic inflation suffered tiny time-dependent deviations from the slow-roll regime, these would induce the existence of small scale-dependent features imprinted in the primordial spectra, with their shapes and sizes revealing information about the physics that produced them. Small sharp features could be suppressed at the level of the two-point correlation function, making them undetectable in the power spectrum, but could be amplified at the level of the three-point correlation function, offering us a window of opportunity to uncover them in the non-Gaussian bispectrum. In this article, we show that sharp features may be analyzed using only data coming from the three point correlation function parametrizing primordial non-Gaussianity. More precisely, we show that if features appear in a particular non-Gaussian triangle configuration (e.g. equilateral, folded, squeezed), these must reappear in every other configuration according to a specific relation allowing us to correlate features across the non-Gaussian bispectrum. As a result, we offer a method to study scale-dependent features generated during inflation that depends only on data coming from measurements of non-Gaussianity, allowing us to omit data from the power spectrum.
Consistency relations for sharp inflationary non-Gaussian features
International Nuclear Information System (INIS)
Mooij, Sander; Palma, Gonzalo A.; Panotopoulos, Grigoris; Soto, Alex
2016-01-01
If cosmic inflation suffered tiny time-dependent deviations from the slow-roll regime, these would induce the existence of small scale-dependent features imprinted in the primordial spectra, with their shapes and sizes revealing information about the physics that produced them. Small sharp features could be suppressed at the level of the two-point correlation function, making them undetectable in the power spectrum, but could be amplified at the level of the three-point correlation function, offering us a window of opportunity to uncover them in the non-Gaussian bispectrum. In this article, we show that sharp features may be analyzed using only data coming from the three point correlation function parametrizing primordial non-Gaussianity. More precisely, we show that if features appear in a particular non-Gaussian triangle configuration (e.g. equilateral, folded, squeezed), these must reappear in every other configuration according to a specific relation allowing us to correlate features across the non-Gaussian bispectrum. As a result, we offer a method to study scale-dependent features generated during inflation that depends only on data coming from measurements of non-Gaussianity, allowing us to omit data from the power spectrum.
Directory of Open Access Journals (Sweden)
Michele Liguori
2010-01-01
Full Text Available The most direct probe of non-Gaussian initial conditions has come from bispectrum measurements of temperature fluctuations in the Cosmic Microwave Background and of the matter and galaxy distribution at large scales. Such bispectrum estimators are expected to continue to provide the best constraints on the non-Gaussian parameters in future observations. We review and compare the theoretical and observational problems, current results, and future prospects for the detection of a nonvanishing primordial component in the bispectrum of the Cosmic Microwave Background and large-scale structure, and the relation to specific predictions from different inflationary models.
Non-Gaussianity from tachyonic preheating in hybrid inflation
International Nuclear Information System (INIS)
Barnaby, Neil; Cline, James M.
2007-01-01
In a previous work we showed that large non-Gaussianities and nonscale-invariant distortions in the cosmic microwave background power spectrum can be generated in hybrid inflation models, due to the contributions of the tachyon (waterfall) field to the second order curvature perturbation. Here we clarify, correct, and extend those results. We show that large non-Gaussianity occurs only when the tachyon remains light throughout inflation, whereas n=4 contamination to the spectrum is the dominant effect when the tachyon is heavy. We find constraints on the parameters of warped-throat brane-antibrane inflation from non-Gaussianity. For F-term and D-term inflation models from supergravity, we obtain nontrivial constraints from the spectral distortion effect. We also establish that our analysis applies to complex tachyon fields
Continuous-variable quantum teleportation with non-Gaussian resources
International Nuclear Information System (INIS)
Dell'Anno, F.; De Siena, S.; Albano, L.; Illuminati, F.
2007-01-01
We investigate continuous variable quantum teleportation using non-Gaussian states of the radiation field as entangled resources. We compare the performance of different classes of degaussified resources, including two-mode photon-added and two-mode photon-subtracted squeezed states. We then introduce a class of two-mode squeezed Bell-like states with one-parameter dependence for optimization. These states interpolate between and include as subcases different classes of degaussified resources. We show that optimized squeezed Bell-like resources yield a remarkable improvement in the fidelity of teleportation both for coherent and nonclassical input states. The investigation reveals that the optimal non-Gaussian resources for continuous variable teleportation are those that most closely realize the simultaneous maximization of the content of entanglement, the degree of affinity with the two-mode squeezed vacuum, and the, suitably measured, amount of non-Gaussianity
Non-Gaussianity in a quasiclassical electronic circuit
Suzuki, Takafumi J.; Hayakawa, Hisao
2017-05-01
We study the non-Gaussian dynamics of a quasiclassical electronic circuit coupled to a mesoscopic conductor. Non-Gaussian noise accompanying the nonequilibrium transport through the conductor significantly modifies the stationary probability density function (PDF) of the flux in the dissipative circuit. We incorporate weak quantum fluctuation of the dissipative LC circuit with a stochastic method and evaluate the quantum correction of the stationary PDF. Furthermore, an inverse formula to infer the statistical properties of the non-Gaussian noise from the stationary PDF is derived in the classical-quantum crossover regime. The quantum correction is indispensable to correctly estimate the microscopic transfer events in the QPC with the quasiclassical inverse formula.
Cosmic microwave background power asymmetry from non-Gaussian modulation.
Schmidt, Fabian; Hui, Lam
2013-01-04
Non-Gaussianity in the inflationary perturbations can couple observable scales to modes of much longer wavelength (even superhorizon), leaving as a signature a large-angle modulation of the observed cosmic microwave background power spectrum. This provides an alternative origin for a power asymmetry that is otherwise often ascribed to a breaking of statistical isotropy. The non-Gaussian modulation effect can be significant even for typical ~10(-5) perturbations while respecting current constraints on non-Gaussianity if the squeezed limit of the bispectrum is sufficiently infrared divergent. Just such a strongly infrared-divergent bispectrum has been claimed for inflation models with a non-Bunch-Davies initial state, for instance. Upper limits on the observed cosmic microwave background power asymmetry place stringent constraints on the duration of inflation in such models.
Primordial non-Gaussian features from DBI Galileon inflation
International Nuclear Information System (INIS)
Choudhury, Sayantan; Pal, Supratik
2015-01-01
We have studied primordial non-Gaussian features of a model of potential-driven single field DBI Galileon inflation. We have computed the bispectrum from the three-point correlation function considering all possible cross correlations between the scalar and tensor modes of the proposed setup. Further, we have computed the trispectrum from a four-point correlation function considering the contribution from contact interaction, and scalar and graviton exchange diagrams in the in-in picture. Finally we have obtained the non-Gaussian consistency conditions from the four-point correlator, which results in partial violation of the Suyama-Yamaguchi four-point consistency relation. This further leads to the conclusion that sufficient primordial non-Gaussianities can be obtained from DBI Galileon inflation. (orig.)
Non-Gaussian diffusion in static disordered media
Luo, Liang; Yi, Ming
2018-04-01
Non-Gaussian diffusion is commonly considered as a result of fluctuating diffusivity, which is correlated in time or in space or both. In this work, we investigate the non-Gaussian diffusion in static disordered media via a quenched trap model, where the diffusivity is spatially correlated. Several unique effects due to quenched disorder are reported. We analytically estimate the diffusion coefficient Ddis and its fluctuation over samples of finite size. We show a mechanism of population splitting in the non-Gaussian diffusion. It results in a sharp peak in the distribution of displacement P (x ,t ) around x =0 , that has frequently been observed in experiments. We examine the fidelity of the coarse-grained diffusion map, which is reconstructed from particle trajectories. Finally, we propose a procedure to estimate the correlation length in static disordered environments, where the information stored in the sample-to-sample fluctuation has been utilized.
IBS for non-gaussian distributions
International Nuclear Information System (INIS)
Fedotov, A.; Sidorin, A.O.; Smirnov, A.V.
2010-01-01
In many situations distribution can significantly deviate from Gaussian which requires accurate treatment of IBS. Our original interest in this problem was motivated by the need to have an accurate description of beam evolution due to IBS while distribution is strongly affected by the external electron cooling force. A variety of models with various degrees of approximation were developed and implemented in BETACOOL in the past to address this topic. A more complete treatment based on the friction coefficient and full 3-D diffusion tensor was introduced in BETACOOL at the end of 2007 under the name 'local IBS model'. Such a model allowed us calculation of IBS for an arbitrary beam distribution. The numerical benchmarking of this local IBS algorithm and its comparison with other models was reported before. In this paper, after briefly describing the model and its limitations, they present its comparison with available experimental data.
Non-Gaussian covariance of CMB B modes of polarization and parameter degradation
International Nuclear Information System (INIS)
Li Chao; Smith, Tristan L.; Cooray, Asantha
2007-01-01
The B-mode polarization lensing signal is a useful probe of the neutrino mass and to a lesser extent the dark energy equation of state as the signal depends on the integrated mass power spectrum between us and the last scattering surface. This lensing B-mode signal, however, is non-Gaussian and the resulting non-Gaussian covariance to the power spectrum could impact cosmological parameter measurements, as correlations between B-mode bins are at a level of 0.1. On the other hand, for temperature and E-mode polarization power spectra, the non-Gaussian covariance is not significant, where we find correlations at the 10 -5 level even for adjacent bins. When the power spectrum is estimated with roughly 5 uniformly spaced bins from l=5 to l=100 and 13 logarithmic uniformly spaced bins from l=100 to l=2000, the resulting degradation on neutrino mass and dark energy equation of state is about a factor of 2 to 3 when compared to the case where statistics are simply considered to be Gaussian. If we increase the total number of bins between l=5 and l=2000 to be about 100, we find that the non-Gaussianities only make a minor difference with less than a few percent correction to uncertainties of most cosmological parameters determined from the data. For Planck, the resulting constraints on the sum of the neutrino masses is σ Σm ν ∼0.2 eV and on the dark energy equation of state parameter we find that σ w ∼0.5. A post-Planck experiment can improve the neutrino mass measurement by a factor of 3 to 4
Lifting Primordial Non-Gaussianity Above the Noise
Welling, Yvette; Woude, Drian van der; Pajer, Enrico
2016-01-01
Primordial non-Gaussianity (PNG) in Large Scale Structures is obfuscated by the many additional sources of non-linearity. Within the Effective Field Theory approach to Standard Perturbation Theory, we show that matter non-linearities in the bispectrum can be modeled sufficiently well to strengthen
Searching for non-Gaussianity in the WMAP data
International Nuclear Information System (INIS)
Bernui, A.; Reboucas, M. J.
2009-01-01
Some analyses of recent cosmic microwave background (CMB) data have provided hints that there are deviations from Gaussianity in the WMAP CMB temperature fluctuations. Given the far-reaching consequences of such a non-Gaussianity for our understanding of the physics of the early universe, it is important to employ alternative indicators in order to determine whether the reported non-Gaussianity is of cosmological origin, and/or extract further information that may be helpful for identifying its causes. We propose two new non-Gaussianity indicators, based on skewness and kurtosis of large-angle patches of CMB maps, which provide a measure of departure from Gaussianity on large angular scales. A distinctive feature of these indicators is that they provide sky maps of non-Gaussianity of the CMB temperature data, thus allowing a possible additional window into their origins. Using these indicators, we find no significant deviation from Gaussianity in the three and five-year WMAP Internal Linear Combination (ILC) map with KQ75 mask, while the ILC unmasked map exhibits deviation from Gaussianity, quantifying therefore the WMAP team recommendation to employ the new mask KQ75 for tests of Gaussianity. We also use our indicators to test for Gaussianity the single frequency foreground unremoved WMAP three and five-year maps, and show that the K and Ka maps exhibit a clear indication of deviation from Gaussianity even with the KQ75 mask. We show that our findings are robust with respect to the details of the method.
Planck 2013 Results. XXIV. Constraints on primordial non-Gaussianity
DEFF Research Database (Denmark)
Ade, P. A. R.; Aghanim, N.; Armitage-Caplan, C.
2013-01-01
The Planck nominal mission cosmic microwave background (CMB) maps yield unprecedented constraints on primordial non-Gaussianity (NG).Using three optimal bispectrum estimators, separable template-fitting (KSW), binned, and modal, we obtain consistent values for the primordiallocal, equilateral, an...
Superstatistical generalised Langevin equation: non-Gaussian viscoelastic anomalous diffusion
Ślęzak, Jakub; Metzler, Ralf; Magdziarz, Marcin
2018-02-01
Recent advances in single particle tracking and supercomputing techniques demonstrate the emergence of normal or anomalous, viscoelastic diffusion in conjunction with non-Gaussian distributions in soft, biological, and active matter systems. We here formulate a stochastic model based on a generalised Langevin equation in which non-Gaussian shapes of the probability density function and normal or anomalous diffusion have a common origin, namely a random parametrisation of the stochastic force. We perform a detailed analysis demonstrating how various types of parameter distributions for the memory kernel result in exponential, power law, or power-log law tails of the memory functions. The studied system is also shown to exhibit a further unusual property: the velocity has a Gaussian one point probability density but non-Gaussian joint distributions. This behaviour is reflected in the relaxation from a Gaussian to a non-Gaussian distribution observed for the position variable. We show that our theoretical results are in excellent agreement with stochastic simulations.
Non-Gaussian Methods for Causal Structure Learning.
Shimizu, Shohei
2018-05-22
Causal structure learning is one of the most exciting new topics in the fields of machine learning and statistics. In many empirical sciences including prevention science, the causal mechanisms underlying various phenomena need to be studied. Nevertheless, in many cases, classical methods for causal structure learning are not capable of estimating the causal structure of variables. This is because it explicitly or implicitly assumes Gaussianity of data and typically utilizes only the covariance structure. In many applications, however, non-Gaussian data are often obtained, which means that more information may be contained in the data distribution than the covariance matrix is capable of containing. Thus, many new methods have recently been proposed for using the non-Gaussian structure of data and inferring the causal structure of variables. This paper introduces prevention scientists to such causal structure learning methods, particularly those based on the linear, non-Gaussian, acyclic model known as LiNGAM. These non-Gaussian data analysis tools can fully estimate the underlying causal structures of variables under assumptions even in the presence of unobserved common causes. This feature is in contrast to other approaches. A simulated example is also provided.
Continuous variable entanglement distillation of non-Gaussian states
DEFF Research Database (Denmark)
Lassen, Mikael Østergaard; Dong, Ruifang; Heersink, Joel
2009-01-01
We experimentally demonstrate distillation of continuous variable entangled light that has undergone non-Gaussian attenuation loss. The continuous variable entanglement is generated with optical fibers and sent through a lossy channel, where the transmission is varying in time. By employing simple...
Karagiannis, Dionysios; Lazanu, Andrei; Liguori, Michele; Raccanelli, Alvise; Bartolo, Nicola; Verde, Licia
2018-07-01
We forecast constraints on primordial non-Gaussianity (PNG) and bias parameters from measurements of galaxy power spectrum and bispectrum in future radio continuum and optical surveys. In the galaxy bispectrum, we consider a comprehensive list of effects, including the bias expansion for non-Gaussian initial conditions up to second order, redshift space distortions, redshift uncertainties and theoretical errors. These effects are all combined in a single PNG forecast for the first time. Moreover, we improve the bispectrum modelling over previous forecasts, by accounting for trispectrum contributions. All effects have an impact on final predicted bounds, which varies with the type of survey. We find that the bispectrum can lead to improvements up to a factor ˜5 over bounds based on the power spectrum alone, leading to significantly better constraints for local-type PNG, with respect to current limits from Planck. Future radio and photometric surveys could obtain a measurement error of σ (f_{NL}^{loc}) ≈ 0.2. In the case of equilateral PNG, galaxy bispectrum can improve upon present bounds only if significant improvements in the redshift determinations of future, large volume, photometric or radio surveys could be achieved. For orthogonal non-Gaussianity, expected constraints are generally comparable to current ones.
Neutron study of non-Gaussian self dynamics in liquid parahydrogen
International Nuclear Information System (INIS)
Bafile, Ubaldo; Celli, Milva; Colognesi, Daniele; Zoppi, Marco; Guarini, Eleonora; De Francesco, Alessio; Formisano, Ferdinando; Neumann, Martin
2012-01-01
A time-honoured approach to single-molecule, or self, dynamics of liquids is based on the so-called Gaussian approximation (GA), where it is assumed that, in the whole dynamical range between hydrodynamic diffusion and free-particle streaming, the motion of a particle is fully determined by a unique function of time directly related to the velocity autocorrelation function. An evident support to the GA is offered by the fact that the approximation becomes exact in both above limit conditions. Yet, experimental inquiries into the presence of non-Gaussian dynamics are very scarce, particularly in liquid parahydrogen in spite of its importance as the prototype of a 'quantum Boltzmann liquid' which has also served as a benchmark for the development of quantum dynamics simulation algorithms. Though experimental evidence of the breakdown of the GA was obtained by some of the authors a few years ago, the localization in Q space of non-Gaussian behaviour was still undetermined, and no quantitative assessment of the effect was ever obtained. These issues have been tackled and solved by a new neutron investigation, which provides the first determination of non-Gaussian behaviour in the framework of the well-known theoretical approach by Rahman, Singwi and Sjölander.
Karagiannis, Dionysios; Lazanu, Andrei; Liguori, Michele; Raccanelli, Alvise; Bartolo, Nicola; Verde, Licia
2018-04-01
We forecast constraints on primordial non-Gaussianity (PNG) and bias parameters from measurements of galaxy power spectrum and bispectrum in future radio continuum and optical surveys. In the galaxy bispectrum, we consider a comprehensive list of effects, including the bias expansion for non-Gaussian initial conditions up to second order, redshift space distortions, redshift uncertainties and theoretical errors. These effects are all combined in a single PNG forecast for the first time. Moreover, we improve the bispectrum modelling over previous forecasts, by accounting for trispectrum contributions. All effects have an impact on final predicted bounds, which varies with the type of survey. We find that the bispectrum can lead to improvements up to a factor ˜5 over bounds based on the power spectrum alone, leading to significantly better constraints for local-type PNG, with respect to current limits from Planck. Future radio and photometric surveys could obtain a measurement error of σ (f_{NL}^{loc}) ≈ 0.2. In the case of equilateral PNG, galaxy bispectrum can improve upon present bounds only if significant improvements in the redshift determinations of future, large volume, photometric or radio surveys could be achieved. For orthogonal non-Gaussianity, expected constraints are generally comparable to current ones.
Scale-dependent bias from the reconstruction of non-Gaussian distributions
International Nuclear Information System (INIS)
Chongchitnan, Sirichai; Silk, Joseph
2011-01-01
Primordial non-Gaussianity introduces a scale-dependent variation in the clustering of density peaks corresponding to rare objects. This variation, parametrized by the bias, is investigated on scales where a linear perturbation theory is sufficiently accurate. The bias is obtained directly in real space by comparing the one- and two-point probability distributions of density fluctuations. We show that these distributions can be reconstructed using a bivariate Edgeworth series, presented here up to an arbitrarily high order. The Edgeworth formalism is shown to be well-suited for ''local'' cubic-order non-Gaussianity parametrized by g NL . We show that a strong scale dependence in the bias can be produced by g NL of order 10 5 , consistent with cosmic microwave background constraints. On a separation length of ∼100 Mpc, current constraints on g NL still allow the bias for the most massive clusters to be enhanced by 20-30% of the Gaussian value. We further examine the bias as a function of mass scale, and also explore the relationship between the clustering and the abundance of massive clusters in the presence of g NL . We explain why the Edgeworth formalism, though technically challenging, is a very powerful technique for constraining high-order non-Gaussianity with large-scale structures.
MEASURING PRIMORDIAL NON-GAUSSIANITY THROUGH WEAK-LENSING PEAK COUNTS
International Nuclear Information System (INIS)
Marian, Laura; Hilbert, Stefan; Smith, Robert E.; Schneider, Peter; Desjacques, Vincent
2011-01-01
We explore the possibility of detecting primordial non-Gaussianity of the local type using weak-lensing peak counts. We measure the peak abundance in sets of simulated weak-lensing maps corresponding to three models f NL = 0, - 100, and 100. Using survey specifications similar to those of EUCLID and without assuming any knowledge of the lens and source redshifts, we find the peak functions of the non-Gaussian models with f NL = ±100 to differ by up to 15% from the Gaussian peak function at the high-mass end. For the assumed survey parameters, the probability of fitting an f NL = 0 peak function to the f NL = ±100 peak functions is less than 0.1%. Assuming the other cosmological parameters are known, f NL can be measured with an error Δf NL ∼ 13. It is therefore possible that future weak-lensing surveys like EUCLID and LSST may detect primordial non-Gaussianity from the abundance of peak counts, and provide information complementary to that obtained from the cosmic microwave background.
Making tensor factorizations robust to non-gaussian noise.
Energy Technology Data Exchange (ETDEWEB)
Chi, Eric C. (Rice University, Houston, TX); Kolda, Tamara Gibson
2011-03-01
Tensors are multi-way arrays, and the CANDECOMP/PARAFAC (CP) tensor factorization has found application in many different domains. The CP model is typically fit using a least squares objective function, which is a maximum likelihood estimate under the assumption of independent and identically distributed (i.i.d.) Gaussian noise. We demonstrate that this loss function can be highly sensitive to non-Gaussian noise. Therefore, we propose a loss function based on the 1-norm because it can accommodate both Gaussian and grossly non-Gaussian perturbations. We also present an alternating majorization-minimization (MM) algorithm for fitting a CP model using our proposed loss function (CPAL1) and compare its performance to the workhorse algorithm for fitting CP models, CP alternating least squares (CPALS).
Non-gaussianity from the trispectrum and vector field perturbations
International Nuclear Information System (INIS)
Valenzuela-Toledo, Cesar A.; Rodriguez, Yeinzon
2010-01-01
We use the δN formalism to study the trispectrum T ζ of the primordial curvature perturbation ζ when the latter is generated by vector field perturbations, considering the tree-level and one-loop contributions. The order of magnitude of the level of non-gaussianity in the trispectrum, τ NL , is calculated in this scenario and related to the order of magnitude of the level of non-gaussianity in the bispectrum, f NL , and the level of statistical anisotropy in the power spectrum, g ζ . Such consistency relations will put under test this scenario against future observations. Comparison with the expected observational bound on τ NL from WMAP, for generic inflationary models, is done.
Non-gaussianity from the trispectrum and vector field perturbations
Energy Technology Data Exchange (ETDEWEB)
Valenzuela-Toledo, Cesar A., E-mail: cavalto@ciencias.uis.edu.c [Escuela de Fisica, Universidad Industrial de Santander, Ciudad Universitaria, Bucaramanga (Colombia); Rodriguez, Yeinzon, E-mail: yeinzon.rodriguez@uan.edu.c [Escuela de Fisica, Universidad Industrial de Santander, Ciudad Universitaria, Bucaramanga (Colombia); Centro de Investigaciones, Universidad Antonio Narino, Cra 3 Este 47A-15, Bogota D.C. (Colombia)
2010-03-01
We use the deltaN formalism to study the trispectrum T{sub z}eta of the primordial curvature perturbation zeta when the latter is generated by vector field perturbations, considering the tree-level and one-loop contributions. The order of magnitude of the level of non-gaussianity in the trispectrum, tau{sub NL}, is calculated in this scenario and related to the order of magnitude of the level of non-gaussianity in the bispectrum, f{sub NL}, and the level of statistical anisotropy in the power spectrum, g{sub z}eta. Such consistency relations will put under test this scenario against future observations. Comparison with the expected observational bound on tau{sub NL} from WMAP, for generic inflationary models, is done.
Nonlinear and non-Gaussian Bayesian based handwriting beautification
Shi, Cao; Xiao, Jianguo; Xu, Canhui; Jia, Wenhua
2013-03-01
A framework is proposed in this paper to effectively and efficiently beautify handwriting by means of a novel nonlinear and non-Gaussian Bayesian algorithm. In the proposed framework, format and size of handwriting image are firstly normalized, and then typeface in computer system is applied to optimize vision effect of handwriting. The Bayesian statistics is exploited to characterize the handwriting beautification process as a Bayesian dynamic model. The model parameters to translate, rotate and scale typeface in computer system are controlled by state equation, and the matching optimization between handwriting and transformed typeface is employed by measurement equation. Finally, the new typeface, which is transformed from the original one and gains the best nonlinear and non-Gaussian optimization, is the beautification result of handwriting. Experimental results demonstrate the proposed framework provides a creative handwriting beautification methodology to improve visual acceptance.
A non-Gaussian approach to risk measures
Bormetti, Giacomo; Cisana, Enrica; Montagna, Guido; Nicrosini, Oreste
2007-03-01
Reliable calculations of financial risk require that the fat-tailed nature of prices changes is included in risk measures. To this end, a non-Gaussian approach to financial risk management is presented, modelling the power-law tails of the returns distribution in terms of a Student- t distribution. Non-Gaussian closed-form solutions for value-at-risk and expected shortfall are obtained and standard formulae known in the literature under the normality assumption are recovered as a special case. The implications of the approach for risk management are demonstrated through an empirical analysis of financial time series from the Italian stock market and in comparison with the results of the most widely used procedures of quantitative finance. Particular attention is paid to quantify the size of the errors affecting the market risk measures obtained according to different methodologies, by employing a bootstrap technique.
Identification and estimation of non-Gaussian structural vector autoregressions
DEFF Research Database (Denmark)
Lanne, Markku; Meitz, Mika; Saikkonen, Pentti
-Gaussian components is, without any additional restrictions, identified and leads to (essentially) unique impulse responses. We also introduce an identification scheme under which the maximum likelihood estimator of the non-Gaussian SVAR model is consistent and asymptotically normally distributed. As a consequence......, additional economic identifying restrictions can be tested. In an empirical application, we find a negative impact of a contractionary monetary policy shock on financial markets, and clearly reject the commonly employed recursive identifying restrictions....
Current inversion induced by colored non-Gaussian noise
International Nuclear Information System (INIS)
Bag, Bidhan Chandra; Hu, Chin-Kung
2009-01-01
We study a stochastic process driven by colored non-Gaussian noises. For the flashing ratchet model we find that there is a current inversion in the variation of the current with the half-cycle period which accounts for the potential on–off operation. The current inversion almost disappears if one switches from non-Gaussian (NG) to Gaussian (G) noise. We also find that at low value of the asymmetry parameter of the potential the mobility controlled current is more negative for NG noise as compared to G noise. But at large magnitude of the parameter the diffusion controlled positive current is higher for the former than for the latter. On increasing the noise correlation time (τ), keeping the noise strength fixed, the mean velocity of a particle first increases and then decreases after passing through a maximum if the noise is non-Gaussian. For Gaussian noise, the current monotonically decreases. The current increases with the noise parameter p, 0< p<5/3, which is 1 for Gaussian noise
Productive interactions: heavy particles and non-Gaussianity
International Nuclear Information System (INIS)
Flauger, Raphael; Mirbabayi, Mehrdad; Senatore, Leonardo; Silverstein, Eva
2017-01-01
We analyze the shape and amplitude of oscillatory features in the primordial power spectrum and non-Gaussianity induced by periodic production of heavy degrees of freedom coupled to the inflaton φ. We find that non-adiabatic production of particles can contribute effects which are detectable or constrainable using cosmological data even if their time-dependent masses are always heavier than the scale φ̇ 1/2 , much larger than the Hubble scale. This provides a new role for UV completion, consistent with the criteria from effective field theory for when heavy fields cannot be integrated out. This analysis is motivated in part by the structure of axion monodromy, and leads to an additional oscillatory signature in a subset of its parameter space. At the level of a quantum field theory model that we analyze in detail, the effect arises consistently with radiative stability for an interesting window of couplings up to of order ∼< 1. The amplitude of the bispectrum and higher-point functions can be larger than that for Resonant Non-Gaussianity, and its signal/noise may be comparable to that of the corresponding oscillations in the power spectrum (and even somewhat larger within a controlled regime of parameters). Its shape is distinct from previously analyzed templates, but was partly motivated by the oscillatory equilateral searches performed recently by the Planck collaboration. We also make some general comments about the challenges involved in making a systematic study of primordial non-Gaussianity.
Productive interactions: heavy particles and non-Gaussianity
Energy Technology Data Exchange (ETDEWEB)
Flauger, Raphael [Department of Physics, The University of Texas at Austin, Austin, TX, 78712 (United States); Mirbabayi, Mehrdad [Institute for Advanced Study, Princeton, NJ 08540 (United States); Senatore, Leonardo; Silverstein, Eva, E-mail: flauger@physics.ucsd.edu, E-mail: mehrdadm@ias.edu, E-mail: senatore@stanford.edu, E-mail: evas@slac.stanford.edu [Stanford Institute for Theoretical Physics, Stanford University, Stanford, CA 94305 (United States)
2017-10-01
We analyze the shape and amplitude of oscillatory features in the primordial power spectrum and non-Gaussianity induced by periodic production of heavy degrees of freedom coupled to the inflaton φ. We find that non-adiabatic production of particles can contribute effects which are detectable or constrainable using cosmological data even if their time-dependent masses are always heavier than the scale φ̇{sup 1/2}, much larger than the Hubble scale. This provides a new role for UV completion, consistent with the criteria from effective field theory for when heavy fields cannot be integrated out. This analysis is motivated in part by the structure of axion monodromy, and leads to an additional oscillatory signature in a subset of its parameter space. At the level of a quantum field theory model that we analyze in detail, the effect arises consistently with radiative stability for an interesting window of couplings up to of order ∼< 1. The amplitude of the bispectrum and higher-point functions can be larger than that for Resonant Non-Gaussianity, and its signal/noise may be comparable to that of the corresponding oscillations in the power spectrum (and even somewhat larger within a controlled regime of parameters). Its shape is distinct from previously analyzed templates, but was partly motivated by the oscillatory equilateral searches performed recently by the Planck collaboration. We also make some general comments about the challenges involved in making a systematic study of primordial non-Gaussianity.
International Nuclear Information System (INIS)
Desjacques, Vincent; Jeong, Donghui; Schmidt, Fabian
2011-01-01
Recent results of N-body simulations have shown that current theoretical models are not able to correctly predict the amplitude of the scale-dependent halo bias induced by primordial non-Gaussianity, for models going beyond the simplest, local quadratic case. Motivated by these discrepancies, we carefully examine three theoretical approaches based on (1) the statistics of thresholded regions, (2) a peak-background split method based on separation of scales, and (3) a peak-background split method using the conditional mass function. We first demonstrate that the statistics of thresholded regions, which is shown to be equivalent at leading order to a local bias expansion, cannot explain the mass-dependent deviation between theory and N-body simulations. In the two formulations of the peak-background split on the other hand, we identify an important, but previously overlooked, correction to the non-Gaussian bias that strongly depends on halo mass. This new term is in general significant for any primordial non-Gaussianity going beyond the simplest local f NL model. In a separate paper (to be published in PRD rapid communication), the authors compare these new theoretical predictions with N-body simulations, showing good agreement for all simulated types of non-Gaussianity.
Extracting foreground-obscured μ-distortion anisotropies to constrain primordial non-Gaussianity
Remazeilles, M.; Chluba, J.
2018-04-01
Correlations between cosmic microwave background (CMB) temperature, polarization and spectral distortion anisotropies can be used as a probe of primordial non-Gaussianity. Here, we perform a reconstruction of μ-distortion anisotropies in the presence of Galactic and extragalactic foregrounds, applying the so-called Constrained ILC component separation method to simulations of proposed CMB space missions (PIXIE, LiteBIRD, CORE, PICO). Our sky simulations include Galactic dust, Galactic synchrotron, Galactic free-free, thermal Sunyaev-Zeldovich effect, as well as primary CMB temperature and μ-distortion anisotropies, the latter being added as correlated field. The Constrained ILC method allows us to null the CMB temperature anisotropies in the reconstructed μ-map (and vice versa), in addition to mitigating the contaminations from astrophysical foregrounds and instrumental noise. We compute the cross-power spectrum between the reconstructed (CMB-free) μ-distortion map and the (μ-free) CMB temperature map, after foreground removal and component separation. Since the cross-power spectrum is proportional to the primordial non-Gaussianity parameter, fNL, on scales k˜eq 740 Mpc^{-1}, this allows us to derive fNL-detection limits for the aforementioned future CMB experiments. Our analysis shows that foregrounds degrade the theoretical detection limits (based mostly on instrumental noise) by more than one order of magnitude, with PICO standing the best chance at placing upper limits on scale-dependent non-Gaussianity. We also discuss the dependence of the constraints on the channel sensitivities and chosen bands. Like for B-mode polarization measurements, extended coverage at frequencies ν ≲ 40 GHz and ν ≳ 400 GHz provides more leverage than increased channel sensitivity.
Non-Gaussian ground-state deformations near a black-hole singularity
Hofmann, Stefan; Schneider, Marc
2017-03-01
The singularity theorem by Hawking and Penrose qualifies Schwarzschild black holes as geodesic incomplete space-times. Albeit this is a mathematically rigorous statement, it requires an operational framework that allows us to probe the spacelike singularity via a measurement process. Any such framework necessarily has to be based on quantum theory. As a consequence, the notion of classical completeness needs to be adapted to situations where the only adequate description is in terms of quantum fields in dynamical space-times. It is shown that Schwarzschild black holes turn out to be complete when probed by self-interacting quantum fields in the ground state and in excited states. The measure for populating quantum fields on hypersurfaces in the vicinity of the black-hole singularity goes to zero towards the singularity. This statement is robust under non-Gaussian deformations of and excitations relative to the ground state. The physical relevance of different completeness concepts for black holes is discussed.
Fluctuation relations with intermittent non-Gaussian variables.
Budini, Adrián A
2011-12-01
Nonequilibrium stationary fluctuations may exhibit a special symmetry called fluctuation relations (FRs). Here, we show that this property is always satisfied by the subtraction of two random and independent variables related by a thermodynamiclike change of measure. Taking one of them as a modulated Poisson process, it is demonstrated that intermittence and FRs are compatible properties that may coexist naturally. Strong non-Gaussian features characterize the probability distribution and its generating function. Their associated large deviation functions develop a "kink" at the origin and a plateau regime respectively. Application of this model in different stationary nonequilibrium situations is discussed.
Consistently violating the non-Gaussian consistency relation
International Nuclear Information System (INIS)
Mooij, Sander; Palma, Gonzalo A.
2015-01-01
Non-attractor models of inflation are characterized by the super-horizon evolution of curvature perturbations, introducing a violation of the non-Gaussian consistency relation between the bispectrum's squeezed limit and the power spectrum's spectral index. In this work we show that the bispectrum's squeezed limit of non-attractor models continues to respect a relation dictated by the evolution of the background. We show how to derive this relation using only symmetry arguments, without ever needing to solve the equations of motion for the perturbations
Teleportation of squeezing: Optimization using non-Gaussian resources
Dell'Anno, Fabio; de Siena, Silvio; Adesso, Gerardo; Illuminati, Fabrizio
2010-12-01
We study the continuous-variable quantum teleportation of states, statistical moments of observables, and scale parameters such as squeezing. We investigate the problem both in ideal and imperfect Vaidman-Braunstein-Kimble protocol setups. We show how the teleportation fidelity is maximized and the difference between output and input variances is minimized by using suitably optimized entangled resources. Specifically, we consider the teleportation of coherent squeezed states, exploiting squeezed Bell states as entangled resources. This class of non-Gaussian states, introduced by Illuminati and co-workers [F. Dell’Anno, S. De Siena, L. Albano, and F. Illuminati, Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.76.022301 76, 022301 (2007); F. Dell’Anno, S. De Siena, and F. Illuminati, Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.81.012333 81, 012333 (2010)], includes photon-added and photon-subtracted squeezed states as special cases. At variance with the case of entangled Gaussian resources, the use of entangled non-Gaussian squeezed Bell resources allows one to choose different optimization procedures that lead to inequivalent results. Performing two independent optimization procedures, one can either maximize the state teleportation fidelity, or minimize the difference between input and output quadrature variances. The two different procedures are compared depending on the degrees of displacement and squeezing of the input states and on the working conditions in ideal and nonideal setups.
Holographic non-Gaussianities in general single-field inflation
Energy Technology Data Exchange (ETDEWEB)
Isono, Hiroshi [Department of Physics, Faculty of Science,Chulalongkorn University, Bangkok 10330 (Thailand); Noumi, Toshifumi [Department of Physics and Jockey Club Institute for Advanced Study,Hong Kong University of Science and Technology (Hong Kong); Department of Physics,Kobe University, Kobe 657-8501 (Japan); Shiu, Gary [Department of Physics and Jockey Club Institute for Advanced Study,Hong Kong University of Science and Technology (Hong Kong); Department of Physics, University of Wisconsin-Madison,Madison, WI 53706 (United States); Wong, Sam S.C.; Zhou, Siyi [Department of Physics and Jockey Club Institute for Advanced Study,Hong Kong University of Science and Technology (Hong Kong)
2016-12-07
We use holographic techniques to compute inflationary non-Gaussianities for general single-field inflation, including models with a non-trivial sound speed. In this holographic approach, the inflationary dynamics is captured by a relevant deformation of the dual conformal field theory (CFT) in the UV, while the inflationary correlators are computed by conformal perturbation theory. In this paper, we discuss the effects of higher derivative operators, such as (∂{sub μ}ϕ∂{sup μ}ϕ){sup m}, which are known to induce a non-trivial sound speed and source potentially large non-Gaussianities. We compute the full inflationary bispectra from the deformed CFT correlators. We also discuss the squeezed limit of the bispectra from the viewpoint of operator product expansions. As is generic in the holographic description of inflation, our power spectrum is blue tilted in the UV region. We extend our bispectrum computation to the IR region by resumming the conformal perturbations to all orders. We provide a self-consistent setup which reproduces a red tilted power spectrum, as well as all possible bispectrum shapes in the slow-roll regime.
Conformal Invariance, Dark Energy, and CMB Non-Gaussianity
Antoniadis, Ignatios; Mottola, Emil
2012-01-01
We show that in addition to simple scale invariance, a universe dominated by dark energy naturally gives rise to correlation functions possessing full conformal invariance. This is due to the mathematical isomorphism between the conformal group of certain three dimensional slices of de Sitter space and the de Sitter isometry group SO(4,1). In the standard homogeneous, isotropic cosmological model in which primordial density perturbations are generated during a long vacuum energy dominated de Sitter phase, the embedding of flat spatial R^3 sections in de Sitter space induces a conformal invariant perturbation spectrum and definite prediction for the shape of the non-Gaussian CMB bispectrum. In the case in which the density fluctuations are generated instead on the de Sitter horizon, conformal invariance of the S^2 horizon embedding implies a different but also quite definite prediction for the angular correlations of CMB non-Gaussianity on the sky. Each of these forms for the bispectrum is intrinsic to the sym...
Teleportation of squeezing: Optimization using non-Gaussian resources
International Nuclear Information System (INIS)
Dell'Anno, Fabio; De Siena, Silvio; Illuminati, Fabrizio; Adesso, Gerardo
2010-01-01
We study the continuous-variable quantum teleportation of states, statistical moments of observables, and scale parameters such as squeezing. We investigate the problem both in ideal and imperfect Vaidman-Braunstein-Kimble protocol setups. We show how the teleportation fidelity is maximized and the difference between output and input variances is minimized by using suitably optimized entangled resources. Specifically, we consider the teleportation of coherent squeezed states, exploiting squeezed Bell states as entangled resources. This class of non-Gaussian states, introduced by Illuminati and co-workers [F. Dell'Anno, S. De Siena, L. Albano, and F. Illuminati, Phys. Rev. A 76, 022301 (2007); F. Dell'Anno, S. De Siena, and F. Illuminati, ibid. 81, 012333 (2010)], includes photon-added and photon-subtracted squeezed states as special cases. At variance with the case of entangled Gaussian resources, the use of entangled non-Gaussian squeezed Bell resources allows one to choose different optimization procedures that lead to inequivalent results. Performing two independent optimization procedures, one can either maximize the state teleportation fidelity, or minimize the difference between input and output quadrature variances. The two different procedures are compared depending on the degrees of displacement and squeezing of the input states and on the working conditions in ideal and nonideal setups.
Non-Gaussianity in two-field inflation beyond the slow-roll approximation
Energy Technology Data Exchange (ETDEWEB)
Jung, Gabriel; Tent, Bartjan van, E-mail: gabriel.jung@th.u-psud.fr, E-mail: bartjan.van-tent@th.u-psud.fr [Laboratoire de Physique Théorique (UMR 8627), CNRS, Univ. Paris-Sud, Université Paris-Saclay, Bâtiment 210, 91405 Orsay Cedex (France)
2017-05-01
We use the long-wavelength formalism to investigate the level of bispectral non-Gaussianity produced in two-field inflation models with standard kinetic terms. Even though the Planck satellite has so far not detected any primordial non-Gaussianity, it has tightened the constraints significantly, and it is important to better understand what regions of inflation model space have been ruled out, as well as prepare for the next generation of experiments that might reach the important milestone of Δ f {sub NL}{sup local}=1. We derive an alternative formulation of the previously derived integral expression for f {sub NL}, which makes it easier to physically interpret the result and see which types of potentials can produce large non-Gaussianity. We apply this to the case of a sum potential and show that it is very difficult to satisfy simultaneously the conditions for a large f {sub NL} and the observational constraints on the spectral index n {sub s} . In the case of the sum of two monomial potentials and a constant we explicitly show in which small region of parameter space this is possible, and we show how to construct such a model. Finally, the new general expression for f {sub NL} also allows us to prove that for the sum potential the explicit expressions derived within the slow-roll approximation remain valid even when the slow-roll approximation is broken during the turn of the field trajectory (as long as only the ε slow-roll parameter remains small).
Interferometric probes of many-body localization.
Serbyn, M; Knap, M; Gopalakrishnan, S; Papić, Z; Yao, N Y; Laumann, C R; Abanin, D A; Lukin, M D; Demler, E A
2014-10-03
We propose a method for detecting many-body localization (MBL) in disordered spin systems. The method involves pulsed coherent spin manipulations that probe the dephasing of a given spin due to its entanglement with a set of distant spins. It allows one to distinguish the MBL phase from a noninteracting localized phase and a delocalized phase. In particular, we show that for a properly chosen pulse sequence the MBL phase exhibits a characteristic power-law decay reflecting its slow growth of entanglement. We find that this power-law decay is robust with respect to thermal and disorder averaging, provide numerical simulations supporting our results, and discuss possible experimental realizations in solid-state and cold-atom systems.
Xiang, Yu; Xu, Buqing; Mišta, Ladislav; Tufarelli, Tommaso; He, Qiongyi; Adesso, Gerardo
2017-10-01
Einstein-Podolsky-Rosen (EPR) steering is an asymmetric form of correlations which is intermediate between quantum entanglement and Bell nonlocality, and can be exploited as a resource for quantum communication with one untrusted party. In particular, steering of continuous-variable Gaussian states has been extensively studied theoretically and experimentally, as a fundamental manifestation of the EPR paradox. While most of these studies focused on quadrature measurements for steering detection, two recent works revealed that there exist Gaussian states which are only steerable by suitable non-Gaussian measurements. In this paper we perform a systematic investigation of EPR steering of bipartite Gaussian states by pseudospin measurements, complementing and extending previous findings. We first derive the density-matrix elements of two-mode squeezed thermal Gaussian states in the Fock basis, which may be of independent interest. We then use such a representation to investigate steering of these states as detected by a simple nonlinear criterion, based on second moments of the correlation matrix constructed from pseudospin operators. This analysis reveals previously unexplored regimes where non-Gaussian measurements are shown to be more effective than Gaussian ones to witness steering of Gaussian states in the presence of local noise. We further consider an alternative set of pseudospin observables, whose expectation value can be expressed more compactly in terms of Wigner functions for all two-mode Gaussian states. However, according to the adopted criterion, these observables are found to be always less sensitive than conventional Gaussian observables for steering detection. Finally, we investigate continuous-variable Werner states, which are non-Gaussian mixtures of Gaussian states, and find that pseudospin measurements are always more effective than Gaussian ones to reveal their steerability. Our results provide useful insights on the role of non-Gaussian
Non-Gaussianity and the Cosmic Microwave Background Anisotropies
Bartolo, N; Riotto, A
2010-01-01
We review in a pedagogical way the present status of the impact of non-Gaussianity (NG) on the Cosmic Microwave Background (CMB) anisotropies. We first show how to set the initial conditions at second-order for the (gauge invariant) CMB anisotropies when some primordial NG is present. However, there are many sources of NG in CMB anisotropies, beyond the primordial one, which can contaminate the primordial signal. We mainly focus on the NG generated from the post-inflationary evolution of the CMB anisotropies at second-order in perturbation theory at large and small angular scales, such as the ones generated at the recombination epoch. We show how to derive the equations to study the second-order CMB anisotropies and provide analytical computations to evaluate their contamination to primordial NG (complemented with numerical examples). We also offer a brief summary of other secondary effects. This review requires basic knowledge of the theory of cosmological perturbations at the linear level.
Large non-Gaussianity in non-minimal inflation
Gong, Jinn-Ouk
2011-01-01
We consider a simple inflation model with a complex scalar field coupled to gravity non-minimally. Both the modulus and the angular directions of the complex scalar are slowly rolling, leading to two-field inflation. The modulus direction becomes flat due to the non-minimal coupling, and the angular direction becomes a pseudo-Goldstone boson from a small breaking of the global U(1) symmetry. We show that large non-Gaussianity can be produced during slow-roll inflation under a reasonable assumption on the initial condition of the angular direction. This scenario may be realized in particle physics models such as the Standard Model with two Higgs doublets.
Robust transmission of non-Gaussian entanglement over optical fibers
International Nuclear Information System (INIS)
Biswas, Asoka; Lidar, Daniel A.
2006-01-01
We show how the entanglement in a wide range of continuous variable non-Gaussian states can be preserved against decoherence for long-range quantum communication through an optical fiber. We apply protection via decoherence-free subspaces and quantum dynamical decoupling to this end. The latter is implemented by inserting phase shifters at regular intervals Δ inside the fiber, where Δ is roughly the ratio of the speed of light in the fiber to the bath high-frequency cutoff. Detailed estimates of relevant parameters are provided using the boson-boson model of system-bath interaction for silica fibers and Δ is found to be on the order of a millimeter
Occupational Hearing Loss from Non-Gaussian Noise.
Suter, Alice H
2017-08-01
Noise levels are truly continuous in relatively few occupations, with some degree of intermittency the most common condition. The sound levels of intermittent noise are often referred to as non-Gaussian in that they are not normally distributed in the time domain. In some conditions, intermittent noise affects the ear differently from continuous noise, and it is this assumption that underlies the selection of the 5-dB exchange rate (ER). The scientific and professional communities have debated this assumption over recent decades. This monograph explores the effect of non-Gaussian noise on the auditory system. It begins by summarizing an earlier report by the same author concentrating on the subject of the ER. The conclusions of the earlier report supported the more conservative 3-dB ER with possible adjustments to the permissible exposure limit for certain working conditions. The current document has expanded on the earlier report in light of the relevant research accomplished in the intervening decades. Although some of the animal research has supported the mitigating effect of intermittency, a closer look at many of these studies reveals certain weaknesses, along with the fact that these noise exposures were not usually representative of the conditions under which people actually work. The more recent animal research on complex noise shows that intermittencies do not protect the cochlea and that many of the previous assumptions about the ameliorative effect of intermittencies are no longer valid, lending further support to the 3-dB ER. The neurologic effects of noise on hearing have gained increasing attention in recent years because of improvements in microscopy and immunostaining techniques. Animal experiments showing damage to auditory synapses from noise exposures previously considered harmless may signify the need for a more conservative approach to the assessment of noise-induced hearing loss and consequently the practice of hearing conservation programs.
He, Xiaozhou; Wang, Yin; Tong, Penger
2018-05-01
Non-Gaussian fluctuations with an exponential tail in their probability density function (PDF) are often observed in nonequilibrium steady states (NESSs) and one does not understand why they appear so often. Turbulent Rayleigh-Bénard convection (RBC) is an example of such a NESS, in which the measured PDF P (δ T ) of temperature fluctuations δ T in the central region of the flow has a long exponential tail. Here we show that because of the dynamic heterogeneity in RBC, the exponential PDF is generated by a convolution of a set of dynamics modes conditioned on a constant local thermal dissipation rate ɛ . The conditional PDF G (δ T |ɛ ) of δ T under a constant ɛ is found to be of Gaussian form and its variance σT2 for different values of ɛ follows an exponential distribution. The convolution of the two distribution functions gives rise to the exponential PDF P (δ T ) . This work thus provides a physical mechanism of the observed exponential distribution of δ T in RBC and also sheds light on the origin of non-Gaussian fluctuations in other NESSs.
UV-protected (natural) inflation: primordial fluctuations and non-gaussian features
Energy Technology Data Exchange (ETDEWEB)
Germani, Cristiano; Watanabe, Yuki, E-mail: cristiano.germani@physik.lmu.de, E-mail: yuki.watanabe@physik.lmu.de [Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-University, Theresienstrasse 37, 80333 Munich (Germany)
2011-07-01
We consider the UV-protected inflation, where the inflaton potential is obtained by quantum (one-loop) breaking of a global symmetry into a discrete symmetry. In this model, all coupling scales are sub-Planckian. This is achieved by coupling the inflaton kinetic term to the Einstein tensor such that the friction is enhanced gravitationally at high energies. In this respect, this new interaction makes virtually any potential adequate for inflation while keeping the system perturbative unitary. We show that even if the gravitationally enhanced friction intrinsically contains new nonlinearities, the UV-protected inflation (and any similar models) behaves as a single field scenario with red tilted spectrum and potentially detectable gravitational waves. Interestingly enough, we find that non-Gaussianity of the curvature perturbations in the local form are completely dominated by the nonlinear gauge transformation from the spatially flat to uniform-field gauge and/or by parity violating interactions of the inflaton and gauge bosons. In particular, the parity violating interactions may produce detectable non-Gaussianity.
Polynomial approximation of non-Gaussian unitaries by counting one photon at a time
Arzani, Francesco; Treps, Nicolas; Ferrini, Giulia
2017-05-01
In quantum computation with continuous-variable systems, quantum advantage can only be achieved if some non-Gaussian resource is available. Yet, non-Gaussian unitary evolutions and measurements suited for computation are challenging to realize in the laboratory. We propose and analyze two methods to apply a polynomial approximation of any unitary operator diagonal in the amplitude quadrature representation, including non-Gaussian operators, to an unknown input state. Our protocols use as a primary non-Gaussian resource a single-photon counter. We use the fidelity of the transformation with the target one on Fock and coherent states to assess the quality of the approximate gate.
Skewness and kurtosis analysis for non-Gaussian distributions
Celikoglu, Ahmet; Tirnakli, Ugur
2018-06-01
In this paper we address a number of pitfalls regarding the use of kurtosis as a measure of deviations from the Gaussian. We treat kurtosis in both its standard definition and that which arises in q-statistics, namely q-kurtosis. We have recently shown that the relation proposed by Cristelli et al. (2012) between skewness and kurtosis can only be verified for relatively small data sets, independently of the type of statistics chosen; however it fails for sufficiently large data sets, if the fourth moment of the distribution is finite. For infinite fourth moments, kurtosis is not defined as the size of the data set tends to infinity. For distributions with finite fourth moments, the size, N, of the data set for which the standard kurtosis saturates to a fixed value, depends on the deviation of the original distribution from the Gaussian. Nevertheless, using kurtosis as a criterion for deciding which distribution deviates further from the Gaussian can be misleading for small data sets, even for finite fourth moment distributions. Going over to q-statistics, we find that although the value of q-kurtosis is finite in the range of 0 < q < 3, this quantity is not useful for comparing different non-Gaussian distributed data sets, unless the appropriate q value, which truly characterizes the data set of interest, is chosen. Finally, we propose a method to determine the correct q value and thereby to compute the q-kurtosis of q-Gaussian distributed data sets.
Modeling Non-Gaussian Time Series with Nonparametric Bayesian Model.
Xu, Zhiguang; MacEachern, Steven; Xu, Xinyi
2015-02-01
We present a class of Bayesian copula models whose major components are the marginal (limiting) distribution of a stationary time series and the internal dynamics of the series. We argue that these are the two features with which an analyst is typically most familiar, and hence that these are natural components with which to work. For the marginal distribution, we use a nonparametric Bayesian prior distribution along with a cdf-inverse cdf transformation to obtain large support. For the internal dynamics, we rely on the traditionally successful techniques of normal-theory time series. Coupling the two components gives us a family of (Gaussian) copula transformed autoregressive models. The models provide coherent adjustments of time scales and are compatible with many extensions, including changes in volatility of the series. We describe basic properties of the models, show their ability to recover non-Gaussian marginal distributions, and use a GARCH modification of the basic model to analyze stock index return series. The models are found to provide better fit and improved short-range and long-range predictions than Gaussian competitors. The models are extensible to a large variety of fields, including continuous time models, spatial models, models for multiple series, models driven by external covariate streams, and non-stationary models.
Constraining primordial non-Gaussianity with cosmological weak lensing: shear and flexion
International Nuclear Information System (INIS)
Fedeli, C.; Bartelmann, M.; Moscardini, L.
2012-01-01
We examine the cosmological constraining power of future large-scale weak lensing surveys on the model of the ESA planned mission Euclid, with particular reference to primordial non-Gaussianity. Our analysis considers several different estimators of the projected matter power spectrum, based on both shear and flexion. We review the covariance and Fisher matrix for cosmic shear and evaluate those for cosmic flexion and for the cross-correlation between the two. The bounds provided by cosmic shear alone are looser than previously estimated, mainly due to the reduced sky coverage and background number density of sources for the latest Euclid specifications. New constraints for the local bispectrum shape, marginalized over σ 8 , are at the level of Δf NL ∼ 100, with the precise value depending on the exact multipole range that is considered in the analysis. We consider three additional bispectrum shapes, for which the cosmic shear constraints range from Δf NL ∼ 340 (equilateral shape) up to Δf NL ∼ 500 (orthogonal shape). Also, constraints on the level of non-Gaussianity and on the amplitude of the matter power spectrum σ 8 are almost perfectly anti-correlated, except for the orthogonal bispectrum shape for which they are correlated. The competitiveness of cosmic flexion constraints against cosmic shear ones depends by and large on the galaxy intrinsic flexion noise, that is still virtually unconstrained. Adopting the very high value that has been occasionally used in the literature results in the flexion contribution being basically negligible with respect to the shear one, and for realistic configurations the former does not improve significantly the constraining power of the latter. Since the shear shot noise is white, while the flexion one decreases with decreasing scale, by considering high enough multipoles the two contributions have to become comparable. Extending the analysis up to l max = 20,000 cosmic flexion, while being still subdominant
Constraining primordial non-Gaussianity with cosmological weak lensing: shear and flexion
Energy Technology Data Exchange (ETDEWEB)
Fedeli, C. [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611-2055 (United States); Bartelmann, M. [Zentrum für Astronomie, Universität Heidelberg, Albert-Überle-Straße 2, 69120 Heidelberg (Germany); Moscardini, L., E-mail: cosimo.fedeli@astro.ufl.edu, E-mail: bartelmann@uni-heidelberg.de, E-mail: lauro.moscardini@unibo.it [Dipartimento di Astronomia, Università di Bologna, Via Ranzani 1, 40127 Bologna (Italy)
2012-10-01
We examine the cosmological constraining power of future large-scale weak lensing surveys on the model of the ESA planned mission Euclid, with particular reference to primordial non-Gaussianity. Our analysis considers several different estimators of the projected matter power spectrum, based on both shear and flexion. We review the covariance and Fisher matrix for cosmic shear and evaluate those for cosmic flexion and for the cross-correlation between the two. The bounds provided by cosmic shear alone are looser than previously estimated, mainly due to the reduced sky coverage and background number density of sources for the latest Euclid specifications. New constraints for the local bispectrum shape, marginalized over σ{sub 8}, are at the level of Δf{sub NL} ∼ 100, with the precise value depending on the exact multipole range that is considered in the analysis. We consider three additional bispectrum shapes, for which the cosmic shear constraints range from Δf{sub NL} ∼ 340 (equilateral shape) up to Δf{sub NL} ∼ 500 (orthogonal shape). Also, constraints on the level of non-Gaussianity and on the amplitude of the matter power spectrum σ{sub 8} are almost perfectly anti-correlated, except for the orthogonal bispectrum shape for which they are correlated. The competitiveness of cosmic flexion constraints against cosmic shear ones depends by and large on the galaxy intrinsic flexion noise, that is still virtually unconstrained. Adopting the very high value that has been occasionally used in the literature results in the flexion contribution being basically negligible with respect to the shear one, and for realistic configurations the former does not improve significantly the constraining power of the latter. Since the shear shot noise is white, while the flexion one decreases with decreasing scale, by considering high enough multipoles the two contributions have to become comparable. Extending the analysis up to l{sub max} = 20,000 cosmic flexion, while
Energy Technology Data Exchange (ETDEWEB)
Li, Yu-Bin; Cai, Yi-Fu [CAS Key Laboratory for Researches in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Chinese Academy of Sciences, Hefei, Anhui 230026 (China); Quintin, Jerome [Department of Physics, McGill University, 3600 rue University, Montréal, QC, H3A 2T8 (Canada); Wang, Dong-Gang, E-mail: lyb2166@mail.ustc.edu.cn, E-mail: jquintin@physics.mcgill.ca, E-mail: wdgang@strw.leidenuniv.nl, E-mail: yifucai@ustc.edu.cn [Leiden Observatory, Leiden University, 2300 RA Leiden (Netherlands)
2017-03-01
We extend the matter bounce scenario to a more general theory in which the background dynamics and cosmological perturbations are generated by a k -essence scalar field with an arbitrary sound speed. When the sound speed is small, the curvature perturbation is enhanced, and the tensor-to-scalar ratio, which is excessively large in the original model, can be sufficiently suppressed to be consistent with observational bounds. Then, we study the primordial three-point correlation function generated during the matter-dominated contraction stage and find that it only depends on the sound speed parameter. Similar to the canonical case, the shape of the bispectrum is mainly dominated by a local form, though for some specific sound speed values a new shape emerges and the scaling behaviour changes. Meanwhile, a small sound speed also results in a large amplitude of non-Gaussianities, which is disfavored by current observations. As a result, it does not seem possible to suppress the tensor-to-scalar ratio without amplifying the production of non-Gaussianities beyond current observational constraints (and vice versa). This suggests an extension of the previously conjectured no-go theorem in single field nonsingular matter bounce cosmologies, which rules out a large class of models. However, the non-Gaussianity results remain as a distinguishable signature of matter bounce cosmology and have the potential to be detected by observations in the near future.
Imprint of primordial non-Gaussianity on dark matter halo profiles
Energy Technology Data Exchange (ETDEWEB)
Dizgah, Azadeh Moradinezhad; Dodelson, Scott; Riotto, Antonio
2013-09-01
We study the impact of primordial non-Gaussianity on the density profile of dark matter halos by using the semi-analytical model introduced recently by Dalal {\\it et al.} which relates the peaks of the initial linear density field to the final density profile of dark matter halos. Models with primordial non-Gaussianity typically produce an initial density field that differs from that produced in Gaussian models. We use the path-integral formulation of excursion set theory to calculate the non-Gaussian corrections to the peak profile and derive the statistics of the peaks of non-Gaussian density field. In the context of the semi-analytic model for halo profiles, currently allowed values for primordial non-Gaussianity would increase the shapes of the inner dark matter profiles, but only at the sub-percent level except in the very innermost regions.
Non-Gaussianities and curvature perturbations from hybrid inflation
Clesse, Sébastien; Garbrecht, Björn; Zhu, Yi
2014-03-01
For the original hybrid inflation as well as the supersymmetric F-term and D-term hybrid models, we calculate the level of non-Gaussianities and the power spectrum of curvature perturbations generated during the waterfall, taking into account the contribution of entropic modes. We focus on the regime of mild waterfall, in which inflation continues for more than about 60 e-folds N during the waterfall. We find that the associated fNL parameter goes typically from fNL≃-1/Nexit in the regime with N ≫60, where Nexit is the number of e-folds between the time of Hubble exit of a pivot scale and the end of inflation, down to fNL˜-0.3 when N ≳60, i.e., much smaller in magnitude than the current bound from Planck. Considering only the adiabatic perturbations, the power spectrum is red, with a spectral index ns=1-4/Nexit in the case N ≫60, whereas in the case N≳60, it increases up to unity. Including the contribution of entropic modes does not change observable predictions in the first case, and the spectral index is too low for this regime to be viable. In the second case, entropic modes are a relevant source for the power spectrum of curvature perturbations, of which the amplitude increases by several orders of magnitude. When spectral index values are consistent with observational constraints, the primordial spectrum amplitude is much larger than the observed value and can even lead to black hole formation. We conclude that, due to the important contribution of entropic modes, the parameter space leading to a mild waterfall phase is excluded by cosmic microwave background observations for all the considered models.
Non-Gaussian probability distributions of solar wind fluctuations
Directory of Open Access Journals (Sweden)
E. Marsch
Full Text Available The probability distributions of field differences ∆x(τ=x(t+τ-x(t, where the variable x(t may denote any solar wind scalar field or vector field component at time t, have been calculated from time series of Helios data obtained in 1976 at heliocentric distances near 0.3 AU. It is found that for comparatively long time lag τ, ranging from a few hours to 1 day, the differences are normally distributed according to a Gaussian. For shorter time lags, of less than ten minutes, significant changes in shape are observed. The distributions are often spikier and narrower than the equivalent Gaussian distribution with the same standard deviation, and they are enhanced for large, reduced for intermediate and enhanced for very small values of ∆x. This result is in accordance with fluid observations and numerical simulations. Hence statistical properties are dominated at small scale τ by large fluctuation amplitudes that are sparsely distributed, which is direct evidence for spatial intermittency of the fluctuations. This is in agreement with results from earlier analyses of the structure functions of ∆x. The non-Gaussian features are differently developed for the various types of fluctuations. The relevance of these observations to the interpretation and understanding of the nature of solar wind magnetohydrodynamic (MHD turbulence is pointed out, and contact is made with existing theoretical concepts of intermittency in fluid turbulence.
On the Shaker Simulation of Wind-Induced Non-Gaussian Random Vibration
Directory of Open Access Journals (Sweden)
Fei Xu
2016-01-01
Full Text Available Gaussian signal is produced by ordinary random vibration controllers to test the products in the laboratory, while the field data is usually non-Gaussian. Two methodologies are presented in this paper for shaker simulation of wind-induced non-Gaussian vibration. The first methodology synthesizes the non-Gaussian signal offline and replicates it on the shaker in the Time Waveform Replication (TWR mode. A new synthesis method is used to model the non-Gaussian signal as a Gaussian signal multiplied by an amplitude modulation function (AMF. A case study is presented to show that the synthesized non-Gaussian signal has the same power spectral density (PSD, probability density function (PDF, and loading cycle distribution (LCD as the field data. The second methodology derives a damage equivalent Gaussian signal from the non-Gaussian signal based on the fatigue damage spectrum (FDS and the extreme response spectrum (ERS and reproduces it on the shaker in the closed-loop frequency domain control mode. The PSD level and the duration time of the derived Gaussian signal can be manipulated for accelerated testing purpose. A case study is presented to show that the derived PSD matches the damage potential of the non-Gaussian environment for both fatigue and peak response.
Gaussian vs non-Gaussian turbulence: impact on wind turbine loads
DEFF Research Database (Denmark)
Berg, Jacob; Natarajan, Anand; Mann, Jakob
2016-01-01
taking into account the safety factor for extreme moments. Other extreme load moments as well as the fatigue loads are not affected because of the use of non-Gaussian turbulent inflow. It is suggested that the turbine thus acts like a low-pass filter that averages out the non-Gaussian behaviour, which......From large-eddy simulations of atmospheric turbulence, a representation of Gaussian turbulence is constructed by randomizing the phases of the individual modes of variability. Time series of Gaussian turbulence are constructed and compared with its non-Gaussian counterpart. Time series from the two...
International Nuclear Information System (INIS)
Giannantonio, Tommaso; Porciani, Cristiano
2010-01-01
We study structure formation in the presence of primordial non-Gaussianity of the local type with parameters f NL and g NL . We show that the distribution of dark-matter halos is naturally described by a multivariate bias scheme where the halo overdensity depends not only on the underlying matter density fluctuation δ but also on the Gaussian part of the primordial gravitational potential φ. This corresponds to a non-local bias scheme in terms of δ only. We derive the coefficients of the bias expansion as a function of the halo mass by applying the peak-background split to common parametrizations for the halo mass function in the non-Gaussian scenario. We then compute the halo power spectrum and halo-matter cross spectrum in the framework of Eulerian perturbation theory up to third order. Comparing our results against N-body simulations, we find that our model accurately describes the numerical data for wave numbers k≤0.1-0.3h Mpc -1 depending on redshift and halo mass. In our multivariate approach, perturbations in the halo counts trace φ on large scales, and this explains why the halo and matter power spectra show different asymptotic trends for k→0. This strongly scale-dependent bias originates from terms at leading order in our expansion. This is different from what happens using the standard univariate local bias where the scale-dependent terms come from badly behaved higher-order corrections. On the other hand, our biasing scheme reduces to the usual local bias on smaller scales, where |φ| is typically much smaller than the density perturbations. We finally discuss the halo bispectrum in the context of multivariate biasing and show that, due to its strong scale and shape dependence, it is a powerful tool for the detection of primordial non-Gaussianity from future galaxy surveys.
Constructive nanolithography and nanochemistry : local probe oxidation and chemical modification
Wouters, D.; Schubert, U.S.
2003-01-01
The possibility to prepare and use submicrometer-sized patterns in successive functionalization reactions with quaternary ammonium salts and (functional) chlorosilanes, as well as cationic gold nanoparticles, is presented. Submicrometer-sized structures were prepared by local probe oxidation of
Feasibility study on the least square method for fitting non-Gaussian noise data
Xu, Wei; Chen, Wen; Liang, Yingjie
2018-02-01
This study is to investigate the feasibility of least square method in fitting non-Gaussian noise data. We add different levels of the two typical non-Gaussian noises, Lévy and stretched Gaussian noises, to exact value of the selected functions including linear equations, polynomial and exponential equations, and the maximum absolute and the mean square errors are calculated for the different cases. Lévy and stretched Gaussian distributions have many applications in fractional and fractal calculus. It is observed that the non-Gaussian noises are less accurately fitted than the Gaussian noise, but the stretched Gaussian cases appear to perform better than the Lévy noise cases. It is stressed that the least-squares method is inapplicable to the non-Gaussian noise cases when the noise level is larger than 5%.
International Nuclear Information System (INIS)
Mirzatuny, Nareg; Khosravi, Shahram; Baghram, Shant; Moshafi, Hossein
2014-01-01
In this work we study the simultaneous effect of primordial non-Gaussianity and the modification of the gravity in f(R) framework on large scale structure observations. We show that non-Gaussianity and modified gravity introduce a scale dependent bias and growth rate functions. The deviation from ΛCDM in the case of primordial non-Gaussian models is in large scales, while the growth rate deviates from ΛCDM in small scales for modified gravity theories. We show that the redshift space distortion can be used to distinguish positive and negative f NL in standard background, while in f(R) theories they are not easily distinguishable. The galaxy power spectrum is generally enhanced in presence of non-Gaussianity and modified gravity. We also obtain the scale dependence of this enhancement. Finally we define galaxy growth rate and galaxy growth rate bias as new observational parameters to constrain cosmology
Transfer of non-Gaussian quantum states of mechanical oscillator to light
Filip, Radim; Rakhubovsky, Andrey A.
2015-11-01
Non-Gaussian quantum states are key resources for quantum optics with continuous-variable oscillators. The non-Gaussian states can be deterministically prepared by a continuous evolution of the mechanical oscillator isolated in a nonlinear potential. We propose feasible and deterministic transfer of non-Gaussian quantum states of mechanical oscillators to a traveling light beam, using purely all-optical methods. The method relies on only basic feasible and high-quality elements of quantum optics: squeezed states of light, linear optics, homodyne detection, and electro-optical feedforward control of light. By this method, a wide range of novel non-Gaussian states of light can be produced in the future from the mechanical states of levitating particles in optical tweezers, including states necessary for the implementation of an important cubic phase gate.
Baura, Alendu; Sen, Monoj Kumar; Goswami, Gurupada; Bag, Bidhan Chandra
2011-01-28
In this paper we have calculated escape rate from a meta stable state in the presence of both colored internal thermal and external nonthermal noises. For the internal noise we have considered usual gaussian distribution but the external noise may be gaussian or non-gaussian in characteristic. The calculated rate is valid for low noise strength of non-gaussian noise such that an effective gaussian approximation of non-gaussian noise wherein the higher order even cumulants of order "4" and higher are neglected. The rate expression we derived here reduces to the known results of the literature, as well as for purely external noise driven activated rate process. The latter exhibits how the rate changes if one switches from non-gaussian to gaussian character of the external noise.
Fitting the Fractional Polynomial Model to Non-Gaussian Longitudinal Data
Directory of Open Access Journals (Sweden)
Ji Hoon Ryoo
2017-08-01
Full Text Available As in cross sectional studies, longitudinal studies involve non-Gaussian data such as binomial, Poisson, gamma, and inverse-Gaussian distributions, and multivariate exponential families. A number of statistical tools have thus been developed to deal with non-Gaussian longitudinal data, including analytic techniques to estimate parameters in both fixed and random effects models. However, as yet growth modeling with non-Gaussian data is somewhat limited when considering the transformed expectation of the response via a linear predictor as a functional form of explanatory variables. In this study, we introduce a fractional polynomial model (FPM that can be applied to model non-linear growth with non-Gaussian longitudinal data and demonstrate its use by fitting two empirical binary and count data models. The results clearly show the efficiency and flexibility of the FPM for such applications.
Elastic–plastic adhesive contact of non-Gaussian rough surfaces
Indian Academy of Sciences (India)
Adhesion; asymmetric roughness; elastic–plastic contact; non-Gaussian rough surfaces. ... model of contact deformation that is based on accurate Finite Element Analysis (FEA) of an elastic–plastic single asperity contact. ... Sadhana | News.
Liguori, M
2008-01-01
We study the impact of cosmological parameters' uncertainties on estimates of the primordial NG parameter f_NL in local and equilateral models of non-Gaussianity. We show that propagating these errors increases the f_NL relative uncertainty by 16% for WMAP and 5 % for Planck in the local case, whereas for equilateral configurations the correction term are 14% and 4%, respectively. If we assume for local f_NL a central value of order 60, according to recent WMAP 5-years estimates, we obtain for Planck a final correction \\Delta f_NL = 3. Although not dramatic, this correction is at the level of the expected estimator uncertainty for Planck, and should then be taken into account when quoting the significance of an eventual future detection. In current estimates of f_NL the cosmological parameters are held fixed at their best-fit values. We finally note that the impact of uncertainties in the cosmological parameters on the final f_NL error bar would become totally negligible if the parameters were allowed to vary...
CMB scale dependent non-Gaussianity from massive gravity during inflation
Energy Technology Data Exchange (ETDEWEB)
Domènech, Guillem; Hiramatsu, Takashi; Lin, Chunshan; Sasaki, Misao [Center for Gravitational Physics, Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto, 606-8502 (Japan); Shiraishi, Maresuke [Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), UTIAS, The University of Tokyo, Chiba, 277-8583 (Japan); Wang, Yi, E-mail: guillem.domenech@yukawa.kyoto-u.ac.jp, E-mail: hiramatz@yukawa.kyoto-u.ac.jp, E-mail: chunshan.lin@yukawa.kyoto-u.ac.jp, E-mail: misao@yukawa.kyoto-u.ac.jp, E-mail: shiraishi-m@t.kagawa-nct.ac.jp, E-mail: phyw@ust.hk [Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China)
2017-05-01
We consider a cosmological model in which the tensor mode becomes massive during inflation, and study the Cosmic Microwave Background (CMB) temperature and polarization bispectra arising from the mixing between the scalar mode and the massive tensor mode during inflation. The model assumes the existence of a preferred spatial frame during inflation. The local Lorentz invariance is already broken in cosmology due to the existence of a preferred rest frame. The existence of a preferred spatial frame further breaks the remaining local SO(3) invariance and in particular gives rise to a mass in the tensor mode. At linear perturbation level, we minimize our model so that the vector mode remains non-dynamical, while the scalar mode is the same as the one in single-field slow-roll inflation. At non-linear perturbation level, this inflationary massive graviton phase leads to a sizeable scalar-scalar-tensor coupling, much greater than the scalar-scalar-scalar one, as opposed to the conventional case. This scalar-scalar-tensor interaction imprints a scale dependent feature in the CMB temperature and polarization bispectra. Very intriguingly, we find a surprizing similarity between the predicted scale dependence and the scale-dependent non-Gaussianities at low multipoles hinted in the WMAP and Planck results.
The virial equation of state for unitary fermion thermodynamics with non-Gaussian correlations
International Nuclear Information System (INIS)
Chen Jisheng; Li Jiarong; Wang Yanping; Xia Xiangjun
2008-01-01
We study the roles of the dynamical high order perturbation and statistically non-linear infrared fluctuation/correlation in the virial equation of state for the Fermi gas in the unitary limit. Incorporating the quantum level crossing rearrangement effects, the spontaneously generated entropy departing from the mean-field theory formalism leads to concise thermodynamical expressions. The dimensionless virial coefficients with complex non-local correlations are calculated up to the fourth order for the first time. The virial coefficients of unitary Fermi gas are found to be proportional to those of the ideal quantum gas with integer ratios through a general term formula. Counterintuitively, contrary to those of the ideal bosons (a (0) 2 =-(1/4√2)) or fermions (a (0) 2 =(1/4√2)), the second virial coefficient a 2 of Fermi gas at unitarity is found to be equal to zero. With the vanishing leading order quantum correction, the BCS–BEC crossover thermodynamics manifests the famous pure classical Boyle's law in the Boltzmann regime. The non-Gaussian correlation phenomena can be validated by studying the Joule–Thomson effect
Non-Gaussian signatures arising from warm inflation driven by geometric tachyon
International Nuclear Information System (INIS)
Bhattacharjee, Anindita; Deshamukhya, Atri
2014-01-01
In a warm inflationary scenario, the initial seeds of density perturbation arise from thermal fluctuations of the inflaton field. These fluctuations in principle have Gaussian distribution. In a Gaussian distribution the density perturbation can be expressed as the two point correlation function. Thus if in an inflationary model the density perturbation is expressed as correlation function of order higher than two, these fluctuations are non-Gaussian in nature. A simple inflationary model containing single scalar field, slow roll, canonical kinetic term and vacuum initial state can produce a tiny amount of non-Gaussianity which are very small to be detected by any experiment. Non-Gaussianity can also arise in inflationary models containing multiple scalar fields. For an inflationary scenario with single scalar field, non-Gaussianity can be expressed in terms of bi-spectrum however for multi field Inflation, it is expressed in terms of trispectrum etc. In this piece of work, the warm inflationary scenario, driven by a D3 brane due to the presence of a stack of k coincident NS 5 branes is considered and the non-Gaussian effects in such an inflationary scenario has been analysed by measuring the bispectrum of the gravitational field fluctuations generated during the warm inflation in strong dissipative regime. The bi-spectrum of the Inflation is expressed in terms of the parameter f NL and it is seen that the value of f NL parameter lies well within the limit observed by WMAP7
Measuring probe for measurement of local velocities
International Nuclear Information System (INIS)
Casal, V.; Arnold, G.; Kirchner, R.; Kussmaul, H.; Miller, H.
1988-03-01
The report describes a method for measurement of local velocities. It bases on the detection of the propagation of a temperature pulse induced into the fluid. The method can also be applied in flowing liquid metals with superimposed magnetic field; in this case common measuring principles fail application. The measuring system discussed consists of, a measuring head, a heating system, amplifiers and a PC. The latter performs process operation, data sampling, and evaluation of velocity. The measuring head itself includes a miniaturized heater (as a pulse marker) heated by the heating system in a short pulse, and a number of thermocouples (sensors) for detection of signals. The design, construction, and examination of a developed measuring device is described. (orig.) [de
A Local Probe for Universal Non-equilibrium Dynamics
2015-06-01
shown are polarizing beam splitters . About 700µW are superimposed with a reference laser on a glass plate and coupled into an optical fiber to detect...A Local Probe for Universal Non -equilibrium Dynamics We report on the results obtained across a nine-month ARO-sponsored project, whose purpose was...to implement a local probe for a gas of ultracold atoms. We used a phase plate with a spiral phase gradient to create a hollow-core laser beam . This
Delay-enhanced stability and stochastic resonance in perception bistability under non-Gaussian noise
International Nuclear Information System (INIS)
Yang, Tao; Zeng, Chunhua; Liu, Ruifen; Wang, Hua; Mei, Dongcheng
2015-01-01
In this paper we investigate the effect of time delay in an attractor network model of perception bistability driven by non-Gaussian noise. Using delay Langevin and Fokker–Planck approaches, the theoretical analysis of the model is presented. It is found that the mean first-passage time (MFPT) as a function of the time delay exhibits a maximum, which is identified as the characteristic of the delay-enhanced stability of the system. This is different to the case of noise-enhanced stability. The non-Gaussian noise-enhanced stability of the system is also analyzed. The signal-to-noise ratio (SNR) as a function of the noise intensity exhibits a maximum. This maximum implies the identifying characteristic of stochastic resonance (SR), and the time delay and non-Gaussian noise can enhance the SR phenomenon. (paper)
A non-Gaussian multivariate distribution with all lower-dimensional Gaussians and related families
Dutta, Subhajit
2014-07-28
Several fascinating examples of non-Gaussian bivariate distributions which have marginal distribution functions to be Gaussian have been proposed in the literature. These examples often clarify several properties associated with the normal distribution. In this paper, we generalize this result in the sense that we construct a pp-dimensional distribution for which any proper subset of its components has the Gaussian distribution. However, the jointpp-dimensional distribution is inconsistent with the distribution of these subsets because it is not Gaussian. We study the probabilistic properties of this non-Gaussian multivariate distribution in detail. Interestingly, several popular tests of multivariate normality fail to identify this pp-dimensional distribution as non-Gaussian. We further extend our construction to a class of elliptically contoured distributions as well as skewed distributions arising from selections, for instance the multivariate skew-normal distribution.
A non-Gaussian multivariate distribution with all lower-dimensional Gaussians and related families
Dutta, Subhajit; Genton, Marc G.
2014-01-01
Several fascinating examples of non-Gaussian bivariate distributions which have marginal distribution functions to be Gaussian have been proposed in the literature. These examples often clarify several properties associated with the normal distribution. In this paper, we generalize this result in the sense that we construct a pp-dimensional distribution for which any proper subset of its components has the Gaussian distribution. However, the jointpp-dimensional distribution is inconsistent with the distribution of these subsets because it is not Gaussian. We study the probabilistic properties of this non-Gaussian multivariate distribution in detail. Interestingly, several popular tests of multivariate normality fail to identify this pp-dimensional distribution as non-Gaussian. We further extend our construction to a class of elliptically contoured distributions as well as skewed distributions arising from selections, for instance the multivariate skew-normal distribution.
Entanglement and Wigner Function Negativity of Multimode Non-Gaussian States
Walschaers, Mattia; Fabre, Claude; Parigi, Valentina; Treps, Nicolas
2017-11-01
Non-Gaussian operations are essential to exploit the quantum advantages in optical continuous variable quantum information protocols. We focus on mode-selective photon addition and subtraction as experimentally promising processes to create multimode non-Gaussian states. Our approach is based on correlation functions, as is common in quantum statistical mechanics and condensed matter physics, mixed with quantum optics tools. We formulate an analytical expression of the Wigner function after the subtraction or addition of a single photon, for arbitrarily many modes. It is used to demonstrate entanglement properties specific to non-Gaussian states and also leads to a practical and elegant condition for Wigner function negativity. Finally, we analyze the potential of photon addition and subtraction for an experimentally generated multimode Gaussian state.
Morisaki, Soichiro; Yokoyama, Jun'ichi; Eda, Kazunari; Itoh, Yousuke
2016-01-01
We introduce a new analysis method to deal with stationary non-Gaussian noises in gravitational wave detectors in terms of the independent component analysis. First, we consider the simplest case where the detector outputs are linear combinations of the inputs, consisting of signals and various noises, and show that this method may be helpful to increase the signal-to-noise ratio. Next, we take into account the time delay between the inputs and the outputs. Finally, we extend our method to nonlinearly correlated noises and show that our method can identify the coupling coefficients and remove non-Gaussian noises. Although we focus on gravitational wave data analysis, our methods are applicable to the detection of any signals under non-Gaussian noises.
Remarks on non-Gaussian fluctuations of the inflaton and constancy of ζ outside the horizon
International Nuclear Information System (INIS)
Mahajan, N; Rangarajan, R
2014-01-01
We have pointed out that the non-Gaussianity arising from cubic self interactions of the inflaton field is proportional to ξN e . For scales of interest N e = 60, and for models such as new inflation, natural inflation, and running mass inflation ξ is large compared to the slow roll parameter. Therefore, the contribution from self interactions should not be outrightly ignored while retaining other terms in the non-Gaussianity parameter f NL . But the N e dependent term seems to imply the growth of non-Gaussianities outside the horizon. Therefore, we have briefly discussed the issue of the constancy of correlations of the curvature perturbation ζ outside the horizon. We have then presented our results on the 3-point function of ζ k , and found that the N e dependent contribution to f NL from self interactions of the inflaton field is cancelled by contributions from other terms associated with non-linearities in cosmological perturbation theory
Non-Gaussian initial conditions in ΛCDM: Newtonian, relativistic, and primordial contributions
International Nuclear Information System (INIS)
Bruni, Marco; Hidalgo, Juan Carlos; Meures, Nikolai; Wands, David
2014-01-01
The goal of the present paper is to set initial conditions for structure formation at nonlinear order, consistent with general relativity, while also allowing for primordial non-Gaussianity. We use the nonlinear continuity and Raychaudhuri equations, which together with the nonlinear energy constraint, determine the evolution of the matter density fluctuation in general relativity. We solve this equations at first and second order in a perturbative expansion, recovering and extending previous results derived in the matter-dominated limit and in the Newtonian regime. We present a second-order solution for the comoving density contrast in a ΛCDM universe, identifying nonlinear contributions coming from the Newtonian growing mode, primordial non-Gaussianity and intrinsic non-Gaussianity, due to the essential nonlinearity of the relativistic constraint equations. We discuss the application of these results to initial conditions in N-body simulations, showing that relativistic corrections mimic a non-zero nonlinear parameter f NL
Quantifying the non-Gaussianity in the EoR 21-cm signal through bispectrum
Majumdar, Suman; Pritchard, Jonathan R.; Mondal, Rajesh; Watkinson, Catherine A.; Bharadwaj, Somnath; Mellema, Garrelt
2018-05-01
The epoch of reionization (EoR) 21-cm signal is expected to be highly non-Gaussian in nature and this non-Gaussianity is also expected to evolve with the progressing state of reionization. Therefore the signal will be correlated between different Fourier modes (k). The power spectrum will not be able capture this correlation in the signal. We use a higher order estimator - the bispectrum - to quantify this evolving non-Gaussianity. We study the bispectrum using an ensemble of simulated 21-cm signal and with a large variety of k triangles. We observe two competing sources driving the non-Gaussianity in the signal: fluctuations in the neutral fraction (x_{H I}) field and fluctuations in the matter density field. We find that the non-Gaussian contribution from these two sources varies, depending on the stage of reionization and on which k modes are being studied. We show that the sign of the bispectrum works as a unique marker to identify which among these two components is driving the non-Gaussianity. We propose that the sign change in the bispectrum, when plotted as a function of triangle configuration cos θ and at a certain stage of the EoR can be used as a confirmative test for the detection of the 21-cm signal. We also propose a new consolidated way to visualize the signal evolution (with evolving \\bar{x}_{H I} or redshift), through the trajectories of the signal in a power spectrum and equilateral bispectrum i.e. P(k) - B(k, k, k) space.
MINIMUM ENTROPY DECONVOLUTION OF ONE-AND MULTI-DIMENSIONAL NON-GAUSSIAN LINEAR RANDOM PROCESSES
Institute of Scientific and Technical Information of China (English)
程乾生
1990-01-01
The minimum entropy deconvolution is considered as one of the methods for decomposing non-Gaussian linear processes. The concept of peakedness of a system response sequence is presented and its properties are studied. With the aid of the peakedness, the convergence theory of the minimum entropy deconvolution is established. The problem of the minimum entropy deconvolution of multi-dimensional non-Gaussian linear random processes is first investigated and the corresponding theory is given. In addition, the relation between the minimum entropy deconvolution and parameter method is discussed.
Non-Gaussian nature of glassy dynamics by cage to cage motion
International Nuclear Information System (INIS)
Vorselaars, Bart; Lyulin, Alexey V.; Michels, M. A. J.; Karatasos, K.
2007-01-01
A model based on a single Brownian particle moving in a periodic effective field is used to understand the non-Gaussian dynamics in glassy systems of cage escape and subsequent recaging, often thought to be caused by a heterogeneous glass structure. The results are compared to molecular-dynamics simulations of systems with varying complexity: quasi-two-dimensional colloidlike particles, atactic polystyrene, and a dendritic glass. The model nicely describes generic features of all three topologically different systems, in particular around the maximum of the non-Gaussian parameter. This maximum is a measure for the average distance between cages
Cosmic Strings and Their Induced Non-Gaussianities in the Cosmic Microwave Background
Directory of Open Access Journals (Sweden)
Christophe Ringeval
2010-01-01
small fraction of the CMB angular power spectrum, cosmic strings could actually be the main source of its non-Gaussianities. In this paper, after having reviewed the basic cosmological properties of a string network, we present the signatures Nambu-Goto cosmic strings would induce in various observables ranging from the one-point function of the temperature anisotropies to the bispectrum and trispectrum. It is shown that string imprints are significantly different than those expected from the primordial type of non-Gaussianity and could therefore be easily distinguished.
A feedback control strategy for the airfoil system under non-Gaussian colored noise excitation
Energy Technology Data Exchange (ETDEWEB)
Huang, Yong, E-mail: hy@njust.edu.cn, E-mail: taogang@njust.edu.cn; Tao, Gang, E-mail: hy@njust.edu.cn, E-mail: taogang@njust.edu.cn [School of Energy and Power Engineering, Nanjing University of Science and Technology, 200 XiaoLingwei Street, Nanjing 210094 (China)
2014-09-01
The stability of a binary airfoil with feedback control under stochastic disturbances, a non-Gaussian colored noise, is studied in this paper. First, based on some approximated theories and methods the non-Gaussian colored noise is simplified to an Ornstein-Uhlenbeck process. Furthermore, via the stochastic averaging method and the logarithmic polar transformation, one dimensional diffusion process can be obtained. At last by applying the boundary conditions, the largest Lyapunov exponent which can determine the almost-sure stability of the system and the effective region of control parameters is calculated.
A feedback control strategy for the airfoil system under non-Gaussian colored noise excitation.
Huang, Yong; Tao, Gang
2014-09-01
The stability of a binary airfoil with feedback control under stochastic disturbances, a non-Gaussian colored noise, is studied in this paper. First, based on some approximated theories and methods the non-Gaussian colored noise is simplified to an Ornstein-Uhlenbeck process. Furthermore, via the stochastic averaging method and the logarithmic polar transformation, one dimensional diffusion process can be obtained. At last by applying the boundary conditions, the largest Lyapunov exponent which can determine the almost-sure stability of the system and the effective region of control parameters is calculated.
Performance and applications of the ORNL local electrode atom probe
International Nuclear Information System (INIS)
Miller, M.K.; Russell, K.F.
2004-01-01
Full text: The commercial introduction in 2003 of the local electrode atom probe (LEAP) developed by Imago Scientific Instruments has made dramatic, orders of magnitude improvements in the data acquisition rate and the size of the analyzed volume compared to previous types of three-dimensional atom probes and other scanning atom probes. This state-of-the-art instrument may be used for the analysis of traditional needle-shaped specimens and specimens fabricated from 'flat' specimens with focused ion beam (FIB) techniques. The advantage of this local electrode configuration is that significantly lower (∼50 %) standing and pulse voltages are required to produce the field strength required to field evaporate ions from the specimen. New high speed (200 kHz) pulse generators coupled with crossed delay line detectors and faster timing systems also enable significantly faster (up to 300 times) data acquisition rates to be achieved. This new design also permits a significantly larger field of view to be analyzed and results in data sets containing up to 10 8 atoms. In the local electrode atom probe, a ∼10-50 μm diameter aperture is typically positioned approximately one aperture diameter in front of the specimen. In order to accurately align the specimen to the aperture in the funnel-shaped electrode, the specimen is mounted on a three axis nanopositioning stage. An approximate alignment is performed while viewing the relative positions of the specimen and the local electrode with a pair of low magnification video cameras and then a pair of higher magnification video cameras attached to long range microscopes. The final alignment is performed with the use of the field evaporated ions from the specimen. A discussion on the alignment of the specimen with the local electrode, the effects of the fields on the specimen, and the effects of aperture size on aperture lifetime will be presented. The performance of the ORNL local electrode atom probe will be described. The
International Nuclear Information System (INIS)
McHugh, Derek; Buzek, Vladimir; Ziman, Mario
2006-01-01
We present a class of non-Gaussian two-mode continuous-variable states for which the separability criterion for Gaussian states can be employed to detect whether they are separable or not. These states reduce to the two-mode Gaussian states as a special case
Realistic continuous-variable quantum teleportation with non-Gaussian resources
International Nuclear Information System (INIS)
Dell'Anno, F.; De Siena, S.; Illuminati, F.
2010-01-01
We present a comprehensive investigation of nonideal continuous-variable quantum teleportation implemented with entangled non-Gaussian resources. We discuss in a unified framework the main decoherence mechanisms, including imperfect Bell measurements and propagation of optical fields in lossy fibers, applying the formalism of the characteristic function. By exploiting appropriate displacement strategies, we compute analytically the success probability of teleportation for input coherent states and two classes of non-Gaussian entangled resources: two-mode squeezed Bell-like states (that include as particular cases photon-added and photon-subtracted de-Gaussified states), and two-mode squeezed catlike states. We discuss the optimization procedure on the free parameters of the non-Gaussian resources at fixed values of the squeezing and of the experimental quantities determining the inefficiencies of the nonideal protocol. It is found that non-Gaussian resources enhance significantly the efficiency of teleportation and are more robust against decoherence than the corresponding Gaussian ones. Partial information on the alphabet of input states allows further significant improvement in the performance of the nonideal teleportation protocol.
Zhu, Tao; Wang, Anzhong; Kirsten, Klaus; Cleaver, Gerald; Sheng, Qin
2018-02-01
Loop quantum cosmology provides a resolution of the classical big bang singularity in the deep Planck era. The evolution, prior to the usual slow-roll inflation, naturally generates excited states at the onset of the slow-roll inflation. It is expected that these quantum gravitational effects could leave its fingerprints on the primordial perturbation spectrum and non-Gaussianity, and lead to some observational evidences in the cosmic microwave background. While the impact of the quantum effects on the primordial perturbation spectrum has been already studied and constrained by current data, in this paper we continue to study such effects but now on the non-Gaussianity of the primordial curvature perturbations. We present detailed and analytical calculations of the non-Gaussianity and show explicitly that the corrections due to the quantum effects are at the same magnitude of the slow-roll parameters in the observable scales and thus are well within current observational constraints. Despite this, we show that the non-Gaussianity in the squeezed limit can be enhanced at superhorizon scales and it is these effects that can yield a large statistical anisotropy on the power spectrum through the Erickcek-Kamionkowski-Carroll mechanism.
Planck 2015 results: XVII. Constraints on primordial non-Gaussianity
DEFF Research Database (Denmark)
Ade, P. A R; Aghanim, N.; Arnaud, M.
2016-01-01
The Planck full mission cosmic microwave background (CMB) temperature and E-mode polarization maps are analysed to obtain constraints on primordial non-Gaussianity (NG). Using three classes of optimal bispectrum estimators – separable template-fitting (KSW), binned, and modal – we obtain consiste...
Spectral shaping for non-Gaussian source spectra in optical coherence tomography
Tripathi, R; Nassif, N. A.; Nelson, JS; Park, B.H.; de Boer, JF
2002-01-01
We present a digital spectral shaping technique to reduce the sidelobes (ringing) of the axial point-spread function in optical coherence tomography for non-Gaussian-shaped source spectra. The spectra of two superluminescent diodes were combined to generate a spectrum with significant modulation.
DEFF Research Database (Denmark)
Franchin, P.; Ditlevsen, Ove Dalager; Kiureghian, Armen Der
2002-01-01
The model correction factor method (MCFM) is used in conjunction with the first-order reliability method (FORM) to solve structural reliability problems involving integrals of non-Gaussian random fields. The approach replaces the limit-state function with an idealized one, in which the integrals ...
PHYSICS OF NON-GAUSSIAN FIELDS AND THE COSMOLOGICAL GENUS STATISTIC
International Nuclear Information System (INIS)
James, J. Berian
2012-01-01
We report a technique to calculate the impact of distinct physical processes inducing non-Gaussianity on the cosmological density field. A natural decomposition of the cosmic genus statistic into an orthogonal polynomial sequence allows complete expression of the scale-dependent evolution of the topology of large-scale structure, in which effects including galaxy bias, nonlinear gravitational evolution, and primordial non-Gaussianity may be delineated. The relationship of this decomposition to previous methods for analyzing the genus statistic is briefly considered and the following applications are made: (1) the expression of certain systematics affecting topological measurements, (2) the quantification of broad deformations from Gaussianity that appear in the genus statistic as measured in the Horizon Run simulation, and (3) the study of the evolution of the genus curve for simulations with primordial non-Gaussianity. These advances improve the treatment of flux-limited galaxy catalogs for use with this measurement and further the use of the genus statistic as a tool for exploring non-Gaussianity.
Self-consistent field theory of protein adsorption in a non-Gaussian polyelectrolyte brush
Biesheuvel, P.M.; Leermakers, F.A.M.; Stuart, M.A.C.
2006-01-01
To describe adsorption of globular protein molecules in a polyelectrolyte brush we use the strong-stretching approximation of the Edwards self-consistent field equation, combined with corrections for a non-Gaussian brush. To describe chemical potentials in this mixture of (globular) species of
Numerically Accelerated Importance Sampling for Nonlinear Non-Gaussian State Space Models
Koopman, S.J.; Lucas, A.; Scharth, M.
2015-01-01
We propose a general likelihood evaluation method for nonlinear non-Gaussian state-space models using the simulation-based method of efficient importance sampling. We minimize the simulation effort by replacing some key steps of the likelihood estimation procedure by numerical integration. We refer
Non-Gaussianities in a two-field generalization of natural inflation
Riquelme M., Simon
2018-04-01
We describe a two-field model that generalizes natural inflation, in which the inflaton is the pseudo-Goldstone boson of an approximate symmetry that is spontaneously broken, and the radial mode is dynamical. We analyze how the dynamics fundamentally depends on the mass of the radial mode and calculate/estimate the non-Gaussianities arising from such a scenario.
Sellentin, Elena; Heavens, Alan F.
2018-01-01
We investigate whether a Gaussian likelihood, as routinely assumed in the analysis of cosmological data, is supported by simulated survey data. We define test statistics, based on a novel method that first destroys Gaussian correlations in a data set, and then measures the non-Gaussian correlations that remain. This procedure flags pairs of data points that depend on each other in a non-Gaussian fashion, and thereby identifies where the assumption of a Gaussian likelihood breaks down. Using this diagnosis, we find that non-Gaussian correlations in the CFHTLenS cosmic shear correlation functions are significant. With a simple exclusion of the most contaminated data points, the posterior for s8 is shifted without broadening, but we find no significant reduction in the tension with s8 derived from Planck cosmic microwave background data. However, we also show that the one-point distributions of the correlation statistics are noticeably skewed, such that sound weak-lensing data sets are intrinsically likely to lead to a systematically low lensing amplitude being inferred. The detected non-Gaussianities get larger with increasing angular scale such that for future wide-angle surveys such as Euclid or LSST, with their very small statistical errors, the large-scale modes are expected to be increasingly affected. The shifts in posteriors may then not be negligible and we recommend that these diagnostic tests be run as part of future analyses.
Spot size characterization of focused non-Gaussian X-ray laser beams
Chalupsky, J.; Krzywinski, J.; Juha, L.; Hajkova, V.; Cihelka, J.; Burian, T.; Vysin, L.; Gaudin, J.; Gleeson, A.; Jurek, M.; Khorsand, A. R.; Klinger, D.; Wabnitz, H.; Sobierajski, R.; Stormer, M.; Tiedtke, K.; Toleikis, S.
2010-01-01
We present a new technique for the characterization of non-Gaussian laser beams which cannot be described by an analytical formula. As a generalization of the beam spot area we apply and refine the definition of so called effective area (A(eff)) [1] in order to avoid using the full-width at half
Directory of Open Access Journals (Sweden)
Shin'ya Nakano
2014-05-01
Full Text Available A hybrid algorithm that combines the ensemble transform Kalman filter (ETKF and the importance sampling approach is proposed. Since the ETKF assumes a linear Gaussian observation model, the estimate obtained by the ETKF can be biased in cases with nonlinear or non-Gaussian observations. The particle filter (PF is based on the importance sampling technique, and is applicable to problems with nonlinear or non-Gaussian observations. However, the PF usually requires an unrealistically large sample size in order to achieve a good estimation, and thus it is computationally prohibitive. In the proposed hybrid algorithm, we obtain a proposal distribution similar to the posterior distribution by using the ETKF. A large number of samples are then drawn from the proposal distribution, and these samples are weighted to approximate the posterior distribution according to the importance sampling principle. Since the importance sampling provides an estimate of the probability density function (PDF without assuming linearity or Gaussianity, we can resolve the bias due to the nonlinear or non-Gaussian observations. Finally, in the next forecast step, we reduce the sample size to achieve computational efficiency based on the Gaussian assumption, while we use a relatively large number of samples in the importance sampling in order to consider the non-Gaussian features of the posterior PDF. The use of the ETKF is also beneficial in terms of the computational simplicity of generating a number of random samples from the proposal distribution and in weighting each of the samples. The proposed algorithm is not necessarily effective in case that the ensemble is located distant from the true state. However, monitoring the effective sample size and tuning the factor for covariance inflation could resolve this problem. In this paper, the proposed hybrid algorithm is introduced and its performance is evaluated through experiments with non-Gaussian observations.
Probing the statistical properties of Anderson localization with quantum emitters
DEFF Research Database (Denmark)
Smolka, Stephan; Nielsen, Henri Thyrrestrup; Sapienza, Luca
2011-01-01
experiments by measuring the intensity of an external light source after propagation through a disordered medium. However, discriminating between Anderson localization and losses in these experiments remains a major challenge. In this paper, we present an alternative approach where we use quantum emitters...... of disorder induced in the photonic crystal, we observe a pronounced increase in the localization length that is attributed to changes in the local density of states, a behavior that is in stark contrast to entirely random systems. The analysis may pave the way for accurate models and the control of Anderson......Wave propagation in disordered media can be strongly modified by multiple scattering and wave interference. Ultimately, the so-called Anderson-localized regime is reached when the waves become strongly confined in space. So far, Anderson localization of light has been probed in transmission...
Durbin, J.; Koopman, S.J.M.
1998-01-01
The analysis of non-Gaussian time series using state space models is considered from both classical and Bayesian perspectives. The treatment in both cases is based on simulation using importance sampling and antithetic variables; Monte Carlo Markov chain methods are not employed. Non-Gaussian
Probing the statistical properties of Anderson localization with quantum emitters
International Nuclear Information System (INIS)
Smolka, Stephan; Thyrrestrup, Henri; Sapienza, Luca; Lehmann, Tau B; Rix, Kristian R; GarcIa, Pedro D; Lodahl, Peter; Froufe-Perez, Luis S
2011-01-01
Wave propagation in disordered media can be strongly modified by multiple scattering and wave interference. Ultimately, the so-called Anderson-localized regime is reached when the waves become strongly confined in space. So far, Anderson localization of light has been probed in transmission experiments by measuring the intensity of an external light source after propagation through a disordered medium. However, discriminating between Anderson localization and losses in these experiments remains a major challenge. In this paper, we present an alternative approach where we use quantum emitters embedded in disordered photonic crystal waveguides as light sources. Anderson-localized modes are efficiently excited and the analysis of the photoluminescence spectra allows us to explore their statistical properties, for example the localization length and average loss length. With increasing the amount of disorder induced in the photonic crystal, we observe a pronounced increase in the localization length that is attributed to changes in the local density of states, a behavior that is in stark contrast to entirely random systems. The analysis may pave the way for accurate models and the control of Anderson localization in disordered photonic crystals.
International Nuclear Information System (INIS)
Jeffrey, Natasha L. S.; Fletcher, Lyndsay; Labrosse, Nicolas
2017-01-01
In a solar flare, a large fraction of the magnetic energy released is converted rapidly to the kinetic energy of non-thermal particles and bulk plasma motion. This will likely result in non-equilibrium particle distributions and turbulent plasma conditions. We investigate this by analyzing the profiles of high temperature extreme ultraviolet emission lines from a major flare (SOL2014-03-29T17:44) observed by the EUV Imaging Spectrometer (EIS) on Hinode . We find that in many locations the line profiles are non-Gaussian, consistent with a kappa distribution of emitting ions with properties that vary in space and time. At the flare footpoints, close to sites of hard X-ray emission from non-thermal electrons, the κ index for the Fe xvi 262.976 Å line at 3 MK takes values of 3–5. In the corona, close to a low-energy HXR source, the Fe xxiii 263.760 Å line at 15 MK shows κ values of typically 4–7. The observed trends in the κ parameter show that we are most likely detecting the properties of the ion population rather than any instrumental effects. We calculate that a non-thermal ion population could exist if locally accelerated on timescales ≤0.1 s. However, observations of net redshifts in the lines also imply the presence of plasma downflows, which could lead to bulk turbulence, with increased non-Gaussianity in cooler regions. Both interpretations have important implications for theories of solar flare particle acceleration.
Influence of large local and non-local bispectra on primordial black hole abundance
International Nuclear Information System (INIS)
Young, Sam; Regan, Donough; Byrnes, Christian T.
2016-01-01
Primordial black holes represent a unique probe to constrain the early universe on small scales—providing the only constraints on the primordial power spectrum on the majority of scales. However, these constraints are strongly dependent on even small amounts of non-Gaussianity, which is unconstrained on scales significantly smaller than those visible in the CMB. This paper goes beyond previous considerations to consider the effects of a bispectrum of the equilateral, orthogonal and local shapes with arbitrary magnitude upon the abundance of primordial black holes. Non-Gaussian density maps of the early universe are generated from a given bispectrum and used to place constraints on the small scale power spectrum. When small, we show that the skewness provides an accurate estimate for how the constraint depends on non-Gaussianity, independently of the shape of the bispectrum. We show that the orthogonal template of non-Gaussianity has an order of magnitude weaker effect on the constraints than the local and equilateral templates
Detecting nonlinearity in time series driven by non-Gaussian noise: the case of river flows
Directory of Open Access Journals (Sweden)
F. Laio
2004-01-01
Full Text Available Several methods exist for the detection of nonlinearity in univariate time series. In the present work we consider riverflow time series to infer the dynamical characteristics of the rainfall-runoff transformation. It is shown that the non-Gaussian nature of the driving force (rainfall can distort the results of such methods, in particular when surrogate data techniques are used. Deterministic versus stochastic (DVS plots, conditionally applied to the decay phases of the time series, are instead proved to be a suitable tool to detect nonlinearity in processes driven by non-Gaussian (Poissonian noise. An application to daily discharges from three Italian rivers provides important clues to the presence of nonlinearity in the rainfall-runoff transformation.
Spot size characterization of focused non-Gaussian X-ray laser beams.
Chalupský, J; Krzywinski, J; Juha, L; Hájková, V; Cihelka, J; Burian, T; Vysín, L; Gaudin, J; Gleeson, A; Jurek, M; Khorsand, A R; Klinger, D; Wabnitz, H; Sobierajski, R; Störmer, M; Tiedtke, K; Toleikis, S
2010-12-20
We present a new technique for the characterization of non-Gaussian laser beams which cannot be described by an analytical formula. As a generalization of the beam spot area we apply and refine the definition of so called effective area (A(eff)) [1] in order to avoid using the full-width at half maximum (FWHM) parameter which is inappropriate for non-Gaussian beams. Furthermore, we demonstrate a practical utilization of our technique for a femtosecond soft X-ray free-electron laser. The ablative imprints in poly(methyl methacrylate) - PMMA and amorphous carbon (a-C) are used to characterize the spatial beam profile and to determine the effective area. Two procedures of the effective area determination are presented in this work. An F-scan method, newly developed in this paper, appears to be a good candidate for the spatial beam diagnostics applicable to lasers of various kinds.
Non-Gaussianity in multi-sound-speed disformally coupled inflation
Energy Technology Data Exchange (ETDEWEB)
De Bruck, Carsten van; Longden, Chris [Consortium for Fundamental Physics, School of Mathematics and Statistics, University of Sheffield, Hounsfield Road, Sheffield S3 7RH (United Kingdom); Koivisto, Tomi, E-mail: C.vandeBruck@sheffield.ac.uk, E-mail: tomi.koivisto@nordita.org, E-mail: cjlongden1@sheffield.ac.uk [Nordita, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, SE-10691 Stockholm (Sweden)
2017-02-01
Most, if not all, scalar-tensor theories are equivalent to General Relativity with a disformally coupled matter sector. In extra-dimensional theories such a coupling can be understood as a result of induction of the metric on a brane that matter is confined to. This article presents a first look at the non-Gaussianities in disformally coupled inflation, a simple two-field model that features a novel kinetic interaction. Cases with both canonical and Dirac-Born-Infeld (DBI) kinetic terms are taken into account, the latter motivated by the possible extra-dimensional origin of the disformality. The computations are carried out for the equilateral configuration in the slow-roll regime, wherein it is found that the non-Gaussianity is typically rather small and negative. This is despite the fact that the new kinetic interaction causes the perturbation modes to propagate with different sounds speeds, which may both significantly deviate from unity during inflation.
Non-Gaussian path integration in self-interacting scalar field theories
International Nuclear Information System (INIS)
Kaya, Ali
2004-01-01
In self-interacting scalar field theories kinetic expansion is an alternative way of calculating the generating functional for Green's functions where the zeroth order non-Gaussian path integral becomes diagonal in x-space and reduces to the product of an ordinary integral at each point which can be evaluated exactly. We discuss how to deal with such functional integrals and propose a new perturbative expansion scheme which combines the elements of the kinetic expansion with the usual perturbation theory techniques. It is then shown that, when the cutoff dependences of the bare parameters in the potential are chosen to have a well defined non-Gaussian path integral without the kinetic term, the theory becomes trivial in the continuum limit
A Network of Kalman Filters for MAI and ISI Compensation in a Non-Gaussian Environment
Directory of Open Access Journals (Sweden)
Sayadi Bessem
2005-01-01
Full Text Available This paper develops a new multiuser detector based on a network of kalman filters (NKF dealing with multiple access-interference (MAI, intersymbol Interference (ISI, and an impulsive observation noise. The two proposed schemes are based on the modeling of the DS-CDMA system by a discrete-time linear system that has non-Gaussian state and measurement noises. By approximating the non-Gaussian densities of the noises by a weighted sum of Gaussian terms and under the common MMSE estimation criterion, we first derive an NKF detector. This version is further optimized by introducing a feedback exploiting the ISI interference structure. The resulting scheme is an NKF detector based on a likelihood ratio test (LRT. Monte-Carlo simulations have shown that the NKF and the NKF based on LRT detectors significantly improve the efficiency and the performance of the classical Kalman algorithm.
A Monte Carlo simulation model for stationary non-Gaussian processes
DEFF Research Database (Denmark)
Grigoriu, M.; Ditlevsen, Ove Dalager; Arwade, S. R.
2003-01-01
includes translation processes and is useful for both Monte Carlo simulation and analytical studies. As for translation processes, the mixture of translation processes can have a wide range of marginal distributions and correlation functions. Moreover, these processes can match a broader range of second...... athe proposed Monte Carlo algorithm and compare features of translation processes and mixture of translation processes. Keywords: Monte Carlo simulation, non-Gaussian processes, sampling theorem, stochastic processes, translation processes......A class of stationary non-Gaussian processes, referred to as the class of mixtures of translation processes, is defined by their finite dimensional distributions consisting of mixtures of finite dimensional distributions of translation processes. The class of mixtures of translation processes...
Non-Gaussianity at tree and one-loop levels from vector field perturbations
International Nuclear Information System (INIS)
Valenzuela-Toledo, Cesar A.; Rodriguez, Yeinzon; Lyth, David H.
2009-01-01
We study the spectrum P ζ and bispectrum B ζ of the primordial curvature perturbation ζ when the latter is generated by scalar and vector field perturbations. The tree-level and one-loop contributions from vector field perturbations are worked out considering the possibility that the one-loop contributions may be dominant over the tree-level terms [both (either) in P ζ and (or) in B ζ ] and vice versa. The level of non-Gaussianity in the bispectrum, f NL , is calculated and related to the level of statistical anisotropy in the power spectrum, g ζ . For very small amounts of statistical anisotropy in the power spectrum, the level of non-Gaussianity may be very high, in some cases exceeding the current observational limit.
Quantum key distribution using continuous-variable non-Gaussian states
Borelli, L. F. M.; Aguiar, L. S.; Roversi, J. A.; Vidiella-Barranco, A.
2016-02-01
In this work, we present a quantum key distribution protocol using continuous-variable non-Gaussian states, homodyne detection and post-selection. The employed signal states are the photon added then subtracted coherent states (PASCS) in which one photon is added and subsequently one photon is subtracted from the field. We analyze the performance of our protocol, compared with a coherent state-based protocol, for two different attacks that could be carried out by the eavesdropper (Eve). We calculate the secret key rate transmission in a lossy line for a superior channel (beam-splitter) attack, and we show that we may increase the secret key generation rate by using the non-Gaussian PASCS rather than coherent states. We also consider the simultaneous quadrature measurement (intercept-resend) attack, and we show that the efficiency of Eve's attack is substantially reduced if PASCS are used as signal states.
Non-Gaussian signatures in the cosmic background radiation from warm inflation
International Nuclear Information System (INIS)
Gupta, S.; Heavens, A.F.; Berera, A.; Matarrese, S.
2002-01-01
We calculate the bispectrum of the gravitational field fluctuations generated during warm inflation, where dissipation of the vacuum potential during inflation is the mechanism for structure formation. The bispectrum is nonzero because of the self-interaction of the scalar field. We compare the predictions with those of standard, or 'supercooled', inflationary models, and consider the detectability of these levels of non-Gaussianity in the bispectrum of the cosmic microwave background. We find that the levels of non-Gaussianity for warm and supercooled inflation are comparable, and overridden by the contribution to the bispectrum due to other physical effects. We also conclude that the resulting bispectrum values will be undetectable in the cosmic microwave background for both the MAP and Planck Surveyor satellites
Learning non-Gaussian Time Series using the Box-Cox Gaussian Process
Rios, Gonzalo; Tobar, Felipe
2018-01-01
Gaussian processes (GPs) are Bayesian nonparametric generative models that provide interpretability of hyperparameters, admit closed-form expressions for training and inference, and are able to accurately represent uncertainty. To model general non-Gaussian data with complex correlation structure, GPs can be paired with an expressive covariance kernel and then fed into a nonlinear transformation (or warping). However, overparametrising the kernel and the warping is known to, respectively, hin...
Non-Gaussian lineshapes and dynamics of time-resolved linear and nonlinear (correlation) spectra.
Dinpajooh, Mohammadhasan; Matyushov, Dmitry V
2014-07-17
Signatures of nonlinear and non-Gaussian dynamics in time-resolved linear and nonlinear (correlation) 2D spectra are analyzed in a model considering a linear plus quadratic dependence of the spectroscopic transition frequency on a Gaussian nuclear coordinate of the thermal bath (quadratic coupling). This new model is contrasted to the commonly assumed linear dependence of the transition frequency on the medium nuclear coordinates (linear coupling). The linear coupling model predicts equality between the Stokes shift and equilibrium correlation functions of the transition frequency and time-independent spectral width. Both predictions are often violated, and we are asking here the question of whether a nonlinear solvent response and/or non-Gaussian dynamics are required to explain these observations. We find that correlation functions of spectroscopic observables calculated in the quadratic coupling model depend on the chromophore's electronic state and the spectral width gains time dependence, all in violation of the predictions of the linear coupling models. Lineshape functions of 2D spectra are derived assuming Ornstein-Uhlenbeck dynamics of the bath nuclear modes. The model predicts asymmetry of 2D correlation plots and bending of the center line. The latter is often used to extract two-point correlation functions from 2D spectra. The dynamics of the transition frequency are non-Gaussian. However, the effect of non-Gaussian dynamics is limited to the third-order (skewness) time correlation function, without affecting the time correlation functions of higher order. The theory is tested against molecular dynamics simulations of a model polar-polarizable chromophore dissolved in a force field water.
Iima, Mami; Kataoka, Masako; Kanao, Shotaro; Kawai, Makiko; Onishi, Natsuko; Koyasu, Sho; Murata, Katsutoshi; Ohashi, Akane; Sakaguchi, Rena; Togashi, Kaori
2018-01-01
We prospectively examined the variability of non-Gaussian diffusion magnetic resonance imaging (MRI) and intravoxel incoherent motion (IVIM) measurements with different numbers of b-values and excitations in normal breast tissue and breast lesions. Thirteen volunteers and fourteen patients with breast lesions (seven malignant, eight benign; one patient had bilateral lesions) were recruited in this prospective study (approved by the Internal Review Board). Diffusion-weighted MRI was performed with 16 b-values (0-2500 s/mm2 with one number of excitations [NEX]) and five b-values (0-2500 s/mm2, 3 NEX), using a 3T breast MRI. Intravoxel incoherent motion (flowing blood volume fraction [fIVIM] and pseudodiffusion coefficient [D*]) and non-Gaussian diffusion (theoretical apparent diffusion coefficient [ADC] at b value of 0 sec/mm2 [ADC0] and kurtosis [K]) parameters were estimated from IVIM and Kurtosis models using 16 b-values, and synthetic apparent diffusion coefficient (sADC) values were obtained from two key b-values. The variabilities between and within subjects and between different diffusion acquisition methods were estimated. There were no statistical differences in ADC0, K, or sADC values between the different b-values or NEX. A good agreement of diffusion parameters was observed between 16 b-values (one NEX), five b-values (one NEX), and five b-values (three NEX) in normal breast tissue or breast lesions. Insufficient agreement was observed for IVIM parameters. There were no statistical differences in the non-Gaussian diffusion MRI estimated values obtained from a different number of b-values or excitations in normal breast tissue or breast lesions. These data suggest that a limited MRI protocol using a few b-values might be relevant in a clinical setting for the estimation of non-Gaussian diffusion MRI parameters in normal breast tissue and breast lesions.
Measurement of Hubble constant: non-Gaussian errors in HST Key Project data
Energy Technology Data Exchange (ETDEWEB)
Singh, Meghendra [Dr. A.P.J. Abdul Kalam Technical University, Uttar Pradesh, Lucknow, 226021 India (India); Gupta, Shashikant; Pandey, Ashwini [Amity University Haryana, Gurgaon, Haryana, 122413 India (India); Sharma, Satendra, E-mail: meghendrasingh_db@yahoo.co.in, E-mail: shashikantgupta.astro@gmail.com, E-mail: satyamkashwini@gmail.com, E-mail: ssharma_phy@yahoo.co.uk [Yobe State University, Damaturu, Yobe State (Nigeria)
2016-08-01
Assuming the Central Limit Theorem, experimental uncertainties in any data set are expected to follow the Gaussian distribution with zero mean. We propose an elegant method based on Kolmogorov-Smirnov statistic to test the above; and apply it on the measurement of Hubble constant which determines the expansion rate of the Universe. The measurements were made using Hubble Space Telescope. Our analysis shows that the uncertainties in the above measurement are non-Gaussian.
Ultrafast probing of core hole localization in N2.
Schöffler, M S; Titze, J; Petridis, N; Jahnke, T; Cole, K; Schmidt, L Ph H; Czasch, A; Akoury, D; Jagutzki, O; Williams, J B; Cherepkov, N A; Semenov, S K; McCurdy, C W; Rescigno, T N; Cocke, C L; Osipov, T; Lee, S; Prior, M H; Belkacem, A; Landers, A L; Schmidt-Böcking, H; Weber, Th; Dörner, R
2008-05-16
Although valence electrons are clearly delocalized in molecular bonding frameworks, chemists and physicists have long debated the question of whether the core vacancy created in a homonuclear diatomic molecule by absorption of a single x-ray photon is localized on one atom or delocalized over both. We have been able to clarify this question with an experiment that uses Auger electron angular emission patterns from molecular nitrogen after inner-shell ionization as an ultrafast probe of hole localization. The experiment, along with the accompanying theory, shows that observation of symmetry breaking (localization) or preservation (delocalization) depends on how the quantum entangled Bell state created by Auger decay is detected by the measurement.
Sufficient condition for a quantum state to be genuinely quantum non-Gaussian
Happ, L.; Efremov, M. A.; Nha, H.; Schleich, W. P.
2018-02-01
We show that the expectation value of the operator \\hat{{ \\mathcal O }}\\equiv \\exp (-c{\\hat{x}}2)+\\exp (-c{\\hat{p}}2) defined by the position and momentum operators \\hat{x} and \\hat{p} with a positive parameter c can serve as a tool to identify quantum non-Gaussian states, that is states that cannot be represented as a mixture of Gaussian states. Our condition can be readily tested employing a highly efficient homodyne detection which unlike quantum-state tomography requires the measurements of only two orthogonal quadratures. We demonstrate that our method is even able to detect quantum non-Gaussian states with positive–definite Wigner functions. This situation cannot be addressed in terms of the negativity of the phase-space distribution. Moreover, we demonstrate that our condition can characterize quantum non-Gaussianity for the class of superposition states consisting of a vacuum and integer multiples of four photons under more than 50 % signal attenuation.
International Nuclear Information System (INIS)
Allen, Bruce; Creighton, Jolien D.E.; Flanagan, Eanna E.; Romano, Joseph D.
2003-01-01
In a previous paper (paper I), we derived a set of near-optimal signal detection techniques for gravitational wave detectors whose noise probability distributions contain non-Gaussian tails. The methods modify standard methods by truncating or clipping sample values which lie in those non-Gaussian tails. The methods were derived, in the frequentist framework, by minimizing false alarm probabilities at fixed false detection probability in the limit of weak signals. For stochastic signals, the resulting statistic consisted of a sum of an autocorrelation term and a cross-correlation term; it was necessary to discard 'by hand' the autocorrelation term in order to arrive at the correct, generalized cross-correlation statistic. In the present paper, we present an alternative derivation of the same signal detection techniques from within the Bayesian framework. We compute, for both deterministic and stochastic signals, the probability that a signal is present in the data, in the limit where the signal-to-noise ratio squared per frequency bin is small, where the signal is nevertheless strong enough to be detected (integrated signal-to-noise ratio large compared to 1), and where the total probability in the non-Gaussian tail part of the noise distribution is small. We show that, for each model considered, the resulting probability is to a good approximation a monotonic function of the detection statistic derived in paper I. Moreover, for stochastic signals, the new Bayesian derivation automatically eliminates the problematic autocorrelation term
Remarks on non-Gaussian fluctuations of the inflaton and constancy of ζ outside the horizon
International Nuclear Information System (INIS)
Mahajan, Namit; Rangarajan, Raghavan
2011-01-01
We point out that the non-Gaussianity arising from cubic self-interactions of the inflaton field is proportional to ξN e where ξ∼V ''' and N e is the number of e-foldings from horizon exit till the end of inflation. For scales of interest N e =60, and for models of inflation such as new inflation, natural inflation, and running mass inflation ξ is large compared to the slow-roll parameter ε∼V '2 . Therefore, the contribution from self-interactions should not be outrightly ignored while retaining other terms in the non-Gaussianity parameter f NL . However, the N e -dependent term seems to imply the growth of non-Gaussianities outside the horizon. Therefore, we briefly discuss the issue of the constancy of correlations of the curvature perturbation ζ outside the horizon. We then calculate the 3-point function of the inflaton fluctuations using the canonical formalism and further obtain the 3-point function of ζ k . We find that the N e -dependent contribution to f NL from self-interactions of the inflaton field is canceled by contributions from other terms associated with nonlinearities in cosmological perturbation theory.
Nonlinear Bayesian Estimation of BOLD Signal under Non-Gaussian Noise
Directory of Open Access Journals (Sweden)
Ali Fahim Khan
2015-01-01
Full Text Available Modeling the blood oxygenation level dependent (BOLD signal has been a subject of study for over a decade in the neuroimaging community. Inspired from fluid dynamics, the hemodynamic model provides a plausible yet convincing interpretation of the BOLD signal by amalgamating effects of dynamic physiological changes in blood oxygenation, cerebral blood flow and volume. The nonautonomous, nonlinear set of differential equations of the hemodynamic model constitutes the process model while the weighted nonlinear sum of the physiological variables forms the measurement model. Plagued by various noise sources, the time series fMRI measurement data is mostly assumed to be affected by additive Gaussian noise. Though more feasible, the assumption may cause the designed filter to perform poorly if made to work under non-Gaussian environment. In this paper, we present a data assimilation scheme that assumes additive non-Gaussian noise, namely, the e-mixture noise, affecting the measurements. The proposed filter MAGSF and the celebrated EKF are put to test by performing joint optimal Bayesian filtering to estimate both the states and parameters governing the hemodynamic model under non-Gaussian environment. Analyses using both the synthetic and real data reveal superior performance of the MAGSF as compared to EKF.
Local probing and stimulation of neuronal cells by optical manipulation
Cojoc, Dan
2014-09-01
During development and in the adult brain, neurons continuously explore the environment searching for guidance cues, leading to the appropriate connections. Elucidating these mechanisms represents a gold goal in neurobiology. Here, I discuss our recent achievements developing new approaches to locally probe the growth cones and stimulate neuronal cell compartments with high spatial and temporal resolution. Optical tweezers force spectroscopy applied in conjunction with metabolic inhibitors reveals new properties of the cytoskeleton dynamics. On the other hand, using optically manipulated microvectors as functionalized beads or filled liposomes, we demonstrate focal stimulation of neurons by small number of signaling molecules.
The microfluidic probe: operation and use for localized surface processing.
Perrault, Cecile M; Qasaimeh, Mohammad A; Juncker, David
2009-06-04
Microfluidic devices allow assays to be performed using minute amounts of sample and have recently been used to control the microenvironment of cells. Microfluidics is commonly associated with closed microchannels which limit their use to samples that can be introduced, and cultured in the case of cells, within a confined volume. On the other hand, micropipetting system have been used to locally perfuse cells and surfaces, notably using push-pull setups where one pipette acts as source and the other one as sink, but the confinement of the flow is difficult in three dimensions. Furthermore, pipettes are fragile and difficult to position and hence are used in static configuration only. The microfluidic probe (MFP) circumvents the constraints imposed by the construction of closed microfluidic channels and instead of enclosing the sample into the microfluidic system, the microfluidic flow can be directly delivered onto the sample, and scanned across the sample, using the MFP. . The injection and aspiration openings are located within a few tens of micrometers of one another so that a microjet injected into the gap is confined by the hydrodynamic forces of the surrounding liquid and entirely aspirated back into the other opening. The microjet can be flushed across the substrate surface and provides a precise tool for localized deposition/delivery of reagents which can be used over large areas by scanning the probe across the surface. In this video we present the microfluidic probe (MFP). We explain in detail how to assemble the MFP, mount it atop an inverted microscope, and align it relative to the substrate surface, and finally show how to use it to process a substrate surface immersed in a buffer.
Directory of Open Access Journals (Sweden)
Georgios C Manikis
Full Text Available The purpose of this study was to compare the performance of four diffusion models, including mono and bi-exponential both Gaussian and non-Gaussian models, in diffusion weighted imaging of rectal cancer.Nineteen patients with rectal adenocarcinoma underwent MRI examination of the rectum before chemoradiation therapy including a 7 b-value diffusion sequence (0, 25, 50, 100, 500, 1000 and 2000 s/mm2 at a 1.5T scanner. Four different diffusion models including mono- and bi-exponential Gaussian (MG and BG and non-Gaussian (MNG and BNG were applied on whole tumor volumes of interest. Two different statistical criteria were recruited to assess their fitting performance, including the adjusted-R2 and Root Mean Square Error (RMSE. To decide which model better characterizes rectal cancer, model selection was relied on Akaike Information Criteria (AIC and F-ratio.All candidate models achieved a good fitting performance with the two most complex models, the BG and the BNG, exhibiting the best fitting performance. However, both criteria for model selection indicated that the MG model performed better than any other model. In particular, using AIC Weights and F-ratio, the pixel-based analysis demonstrated that tumor areas better described by the simplest MG model in an average area of 53% and 33%, respectively. Non-Gaussian behavior was illustrated in an average area of 37% according to the F-ratio, and 7% using AIC Weights. However, the distributions of the pixels best fitted by each of the four models suggest that MG failed to perform better than any other model in all patients, and the overall tumor area.No single diffusion model evaluated herein could accurately describe rectal tumours. These findings probably can be explained on the basis of increased tumour heterogeneity, where areas with high vascularity could be fitted better with bi-exponential models, and areas with necrosis would mostly follow mono-exponential behavior.
Non-Gaussian Autoregressive Processes with Tukey g-and-h Transformations
Yan, Yuan
2017-11-20
When performing a time series analysis of continuous data, for example from climate or environmental problems, the assumption that the process is Gaussian is often violated. Therefore, we introduce two non-Gaussian autoregressive time series models that are able to fit skewed and heavy-tailed time series data. Our two models are based on the Tukey g-and-h transformation. We discuss parameter estimation, order selection, and forecasting procedures for our models and examine their performances in a simulation study. We demonstrate the usefulness of our models by applying them to two sets of wind speed data.
On the non-Gaussian correlation of the primordial curvature perturbation with vector fields
DEFF Research Database (Denmark)
Kumar Jain, Rajeev; Sloth, Martin Snoager
2013-01-01
We compute the three-point cross-correlation function of the primordial curvature perturbation generated during inflation with two powers of a vector field in a model where conformal invariance is broken by a direct coupling of the vector field with the inflaton. If the vector field is identified...... with the electromagnetic field, this correlation would be a non-Gaussian signature of primordial magnetic fields generated during inflation. We find that the signal is maximized for the flattened configuration where the wave number of the curvature perturbation is twice that of the vector field and in this limit...
Primordial non-Gaussianities in single field inflationary models with non-trivial initial states
Energy Technology Data Exchange (ETDEWEB)
Bahrami, Sina; Flanagan, Éanna É., E-mail: sb933@cornell.edu, E-mail: eef3@cornell.edu [Department of Physics, Cornell University, Ithaca, NY 14853 (United States)
2014-10-01
We compute the non-Gaussianities that arise in single field, slow roll inflationary models arising from arbitrary homogeneous initial states, as well as subleading contributions to the power spectrum. Non Bunch-Davies vacuum initial states can arise if the transition to the single field, slow roll inflation phase occurs only shortly before observable modes left the horizon. They can also arise from new physics at high energies that has been integrated out. Our general result for the bispectrum exhibits several features that were previously seen in special cases.
Area of isodensity contours in Gaussian and non-Gaussian fields
International Nuclear Information System (INIS)
Ryden, B.S.
1988-01-01
The area of isodensity contours in a smoothed density field can be measured by the contour-crossing statistic N1, the number of times per unit length that a line drawn through the density field pierces an isodensity contour. The contour-crossing statistic distinguishes between Gaussian and non-Gaussian fields and provides a measure of the effective slope of the power spectrum. The statistic is easy to apply and can be used on pencil beams and slices as well as on a three-dimensional field. 10 references
Parallel logic gates in synthetic gene networks induced by non-Gaussian noise.
Xu, Yong; Jin, Xiaoqin; Zhang, Huiqing
2013-11-01
The recent idea of logical stochastic resonance is verified in synthetic gene networks induced by non-Gaussian noise. We realize the switching between two kinds of logic gates under optimal moderate noise intensity by varying two different tunable parameters in a single gene network. Furthermore, in order to obtain more logic operations, thus providing additional information processing capacity, we obtain in a two-dimensional toggle switch model two complementary logic gates and realize the transformation between two logic gates via the methods of changing different parameters. These simulated results contribute to improve the computational power and functionality of the networks.
Entanglement of a class of non-Gaussian states in disordered harmonic oscillator systems
Abdul-Rahman, Houssam
2018-03-01
For disordered harmonic oscillator systems over the d-dimensional lattice, we consider the problem of finding the bipartite entanglement of the uniform ensemble of the energy eigenstates associated with a particular number of modes. Such an ensemble defines a class of mixed, non-Gaussian entangled states that are labeled, by the energy of the system, in an increasing order. We develop a novel approach to find the exact logarithmic negativity of this class of states. We also prove entanglement bounds and demonstrate that the low energy states follow an area law.
How Non-Gaussian Shocks Affect Risk Premia in Non-Linear DSGE Models
DEFF Research Database (Denmark)
Andreasen, Martin Møller
This paper studies how non-Gaussian shocks affect risk premia in DSGE models approximated to second and third order. Based on an extension of the results in Schmitt-Grohé & Uribe (2004) to third order, we derive propositions for how rare disasters, stochastic volatility, and GARCH affect any risk...... premia in a wide class of DSGE models. To quantify these effects, we then set up a standard New Keynesian DSGE model where total factor productivity includes rare disasters, stochastic volatility, and GARCH. We …find that rare disasters increase the mean level of the 10-year nominal term premium, whereas...
Stochastic differential calculus for Gaussian and non-Gaussian noises: A critical review
Falsone, G.
2018-03-01
In this paper a review of the literature works devoted to the study of stochastic differential equations (SDEs) subjected to Gaussian and non-Gaussian white noises and to fractional Brownian noises is given. In these cases, particular attention must be paid in treating the SDEs because the classical rules of the differential calculus, as the Newton-Leibnitz one, cannot be applied or are applicable with many difficulties. Here all the principal approaches solving the SDEs are reported for any kind of noise, highlighting the negative and positive properties of each one and making the comparisons, where it is possible.
International Nuclear Information System (INIS)
Tan, Cheng-Yang; Fermilab
2006-01-01
One common way for measuring the emittance of an electron beam is with the slits method. The usual approach for analyzing the data is to calculate an emittance that is a subset of the parent emittance. This paper shows an alternative way by using the method of correlations which ties the parameters derived from the beamlets to the actual parameters of the parent emittance. For parent distributions that are Gaussian, this method yields exact results. For non-Gaussian beam distributions, this method yields an effective emittance that can serve as a yardstick for emittance comparisons
Non-Gaussian Autoregressive Processes with Tukey g-and-h Transformations
Yan, Yuan; Genton, Marc G.
2017-01-01
When performing a time series analysis of continuous data, for example from climate or environmental problems, the assumption that the process is Gaussian is often violated. Therefore, we introduce two non-Gaussian autoregressive time series models that are able to fit skewed and heavy-tailed time series data. Our two models are based on the Tukey g-and-h transformation. We discuss parameter estimation, order selection, and forecasting procedures for our models and examine their performances in a simulation study. We demonstrate the usefulness of our models by applying them to two sets of wind speed data.
Probing the cosmological initial conditions using the CMB
Yadav, Amit P. S.
CMB temperature and E-polarization information (Yadav and Wandelt 2005). One of the main motivations of reconstructing the primordial perturbations is to study the primordial non-Gaussianities. Since the amplitude of primordial non-Gaussianity is very small, any enhancement in sensitivity to the primordial features is useful because it improves the characterization of the primordial non-Gaussianity. Our reconstruction allows us to be more sensitive to the primordial features, whereas most of the current probes of non-Gaussianity do not specifically select for them. We have also developed a fast cubic (bispectrum) estimator of non-Gaussianity f NL of local type, using combined temperature and E-polarization data (Yadavet al. 2007). The estimator is computationally efficient, scaling as O( N 3/2 ) compared to the O( N 5/2 ) scaling of the brute force bispectrum calculation for sky maps with N pixels. For the Planck satellite, this translates into a speed-up by factors of millions, reducing the required computing time from thousands of years to just hours and thus making f NL estimation feasible. The speed of our estimator allows us to study its statistical properties using Monte Carlo simulations. Our estimator in its original form was optimal for homogeneous noise. In order to apply our estimator to realistic data, the estimator needed to be able to deal with inhomogeneous noise. We have generalized the fast polarized estimator to deal with inhomogeneous noise. The generalized estimator is also computationally efficient, scaling as O( N 3/2 ). Furthermore, we have studied and characterized our estimators in the presence of realistic noise, finite resolution, incomplete sky-coverage, and using non-Gaussian CMB maps (Yadavet al. 2008a). We have also developed a numerical code to generate CMB temperature and polarization non-Gaussian maps starting from a given primordial non-Gaussianity (f NL ) (Liguori et al. 2007). In the process of non-Gaussian CMB map making, the code
Probing N=2 superconformal field theories with localization
Energy Technology Data Exchange (ETDEWEB)
Fiol, Bartomeu [Departament de Física Fonamental i Institut de Ciències del Cosmos,Universitat de Barcelona,Martí i Franquès 1, 08028 Barcelona, Catalonia (Spain); Garolera, Blai [Escuela de Física, Universidad de Costa Rica,11501-2060 San José (Costa Rica); Torrents, Genís [Departament de Física Fonamental i Institut de Ciències del Cosmos,Universitat de Barcelona,Martí i Franquès 1, 08028 Barcelona, Catalonia (Spain)
2016-01-27
We use supersymmetric localization to study probes of four dimensional Lagrangian N=2 superconformal field theories. We first derive a unique equation for the eigenvalue density of these theories. We observe that these theories have a Wigner eigenvalue density precisely when they satisfy a necessary condition for having a holographic dual with a sensible higher-derivative expansion. We then compute in the saddle-point approximation the vacuum expectation value of 1/2-BPS circular Wilson loops, and the two-point functions of these Wilson loops with the Lagrangian density and with the stress-energy tensor. This last computation also provides the corresponding Bremsstrahlung functions and entanglement entropies. As expected, whenever a finite fraction of the matter is in the fundamental representation, the results are drastically different from those of N=4 supersymmetric Yang-Mills theory.
Detecting Non-Gaussian and Lognormal Characteristics of Temperature and Water Vapor Mixing Ratio
Kliewer, A.; Fletcher, S. J.; Jones, A. S.; Forsythe, J. M.
2017-12-01
Many operational data assimilation and retrieval systems assume that the errors and variables come from a Gaussian distribution. This study builds upon previous results that shows that positive definite variables, specifically water vapor mixing ratio and temperature, can follow a non-Gaussian distribution and moreover a lognormal distribution. Previously, statistical testing procedures which included the Jarque-Bera test, the Shapiro-Wilk test, the Chi-squared goodness-of-fit test, and a composite test which incorporated the results of the former tests were employed to determine locations and time spans where atmospheric variables assume a non-Gaussian distribution. These tests are now investigated in a "sliding window" fashion in order to extend the testing procedure to near real-time. The analyzed 1-degree resolution data comes from the National Oceanic and Atmospheric Administration (NOAA) Global Forecast System (GFS) six hour forecast from the 0Z analysis. These results indicate the necessity of a Data Assimilation (DA) system to be able to properly use the lognormally-distributed variables in an appropriate Bayesian analysis that does not assume the variables are Gaussian.
Maximum Correntropy Criterion Kalman Filter for α-Jerk Tracking Model with Non-Gaussian Noise
Directory of Open Access Journals (Sweden)
Bowen Hou
2017-11-01
Full Text Available As one of the most critical issues for target track, α -jerk model is an effective maneuver target track model. Non-Gaussian noises always exist in the track process, which usually lead to inconsistency and divergence of the track filter. A novel Kalman filter is derived and applied on α -jerk tracking model to handle non-Gaussian noise. The weighted least square solution is presented and the standard Kalman filter is deduced firstly. A novel Kalman filter with the weighted least square based on the maximum correntropy criterion is deduced. The robustness of the maximum correntropy criterion is also analyzed with the influence function and compared with the Huber-based filter, and, moreover, the kernel size of Gaussian kernel plays an important role in the filter algorithm. A new adaptive kernel method is proposed in this paper to adjust the parameter in real time. Finally, simulation results indicate the validity and the efficiency of the proposed filter. The comparison study shows that the proposed filter can significantly reduce the noise influence for α -jerk model.
Non-Gaussian statistics, classical field theory, and realizable Langevin models
International Nuclear Information System (INIS)
Krommes, J.A.
1995-11-01
The direct-interaction approximation (DIA) to the fourth-order statistic Z ∼ left-angle λψ 2 ) 2 right-angle, where λ is a specified operator and ψ is a random field, is discussed from several points of view distinct from that of Chen et al. [Phys. Fluids A 1, 1844 (1989)]. It is shown that the formula for Z DIA already appeared in the seminal work of Martin, Siggia, and Rose (Phys. Rev. A 8, 423 (1973)] on the functional approach to classical statistical dynamics. It does not follow from the original generalized Langevin equation (GLE) of Leith [J. Atmos. Sd. 28, 145 (1971)] and Kraichnan [J. Fluid Mech. 41, 189 (1970)] (frequently described as an amplitude representation for the DIA), in which the random forcing is realized by a particular superposition of products of random variables. The relationship of that GLE to renormalized field theories with non-Gaussian corrections (''spurious vertices'') is described. It is shown how to derive an improved representation, that realizes cumulants through O(ψ 4 ), by adding to the GLE a particular non-Gaussian correction. A Markovian approximation Z DIA M to Z DIA is derived. Both Z DIA and Z DIA M incorrectly predict a Gaussian kurtosis for the steady state of a solvable three-mode example
Non-Gaussian Stochastic Radiation Transfer in Finite Planar Media with Quadratic Scattering
International Nuclear Information System (INIS)
Sallah, M.
2016-01-01
The stochastic radiation transfer is considered in a participating planar finite continuously fluctuating medium characterized by non-Gaussian variability. The problem is considered for diffuse-reflecting boundaries with quadratic Rayleigh scattering. Random variable transformation (RVT) technique is used to get the complete average for the solution functions that are represented by the probability-density function (PDF) of the solution process. RVT algorithm applies a simple integral transformation to the input stochastic process (the extinction function of the medium). This linear transformation enables us to rewrite the stochastic transport equations in terms of the optical random variable (x) and the optical random thickness (L). Then the radiation transfer equation is solved deterministically to get a closed form for the solution as a function of x and L. So, the solution is used to obtain the PDF of the solution functions applying the RVT technique among the input random variable (L) and the output process (the solution functions). The obtained averages of the solution functions are used to get the complete analytical averages for some interesting physical quantities, namely, reflectivity, transmissivity and partial heat fluxes at the medium boundaries. Numerical results are represented graphically for different non-Gaussian probability distribution functions that compared with the corresponding Gaussian PDF.
International Nuclear Information System (INIS)
Chowdhury, P; Majumdar, A S; Sinha, S; Home, D; Mousavi, S V; Mozaffari, M R
2012-01-01
The weak equivalence principle of gravity is examined at the quantum level in two ways. First, the position detection probabilities of particles described by a non-Gaussian wave packet projected upwards against gravity around the classical turning point and also around the point of initial projection are calculated. These probabilities exhibit mass dependence at both these points, thereby reflecting the quantum violation of the weak equivalence principle. Second, the mean arrival time of freely falling particles is calculated using the quantum probability current, which also turns out to be mass dependent. Such a mass dependence is shown to be enhanced by increasing the non-Gaussianity parameter of the wave packet, thus signifying a stronger violation of the weak equivalence principle through a greater departure from Gaussianity of the initial wave packet. The mass dependence of both the position detection probabilities and the mean arrival time vanishes in the limit of large mass. Thus, compatibility between the weak equivalence principle and quantum mechanics is recovered in the macroscopic limit of the latter. A selection of Bohm trajectories is exhibited to illustrate these features in the free fall case. (paper)
Generation of Stationary Non-Gaussian Time Histories with a Specified Cross-spectral Density
Directory of Open Access Journals (Sweden)
David O. Smallwood
1997-01-01
Full Text Available The paper reviews several methods for the generation of stationary realizations of sampled time histories with non-Gaussian distributions and introduces a new method which can be used to control the cross-spectral density matrix and the probability density functions (pdfs of the multiple input problem. Discussed first are two methods for the specialized case of matching the auto (power spectrum, the skewness, and kurtosis using generalized shot noise and using polynomial functions. It is then shown that the skewness and kurtosis can also be controlled by the phase of a complex frequency domain description of the random process. The general case of matching a target probability density function using a zero memory nonlinear (ZMNL function is then covered. Next methods for generating vectors of random variables with a specified covariance matrix for a class of spherically invariant random vectors (SIRV are discussed. Finally the general case of matching the cross-spectral density matrix of a vector of inputs with non-Gaussian marginal distributions is presented.
Comparison of Gaussian and non-Gaussian Atmospheric Profile Retrievals from Satellite Microwave Data
Kliewer, A.; Forsythe, J. M.; Fletcher, S. J.; Jones, A. S.
2017-12-01
The Cooperative Institute for Research in the Atmosphere at Colorado State University has recently developed two different versions of a mixed-distribution (lognormal combined with a Gaussian) based microwave temperature and mixing ratio retrieval system as well as the original Gaussian-based approach. These retrieval systems are based upon 1DVAR theory but have been adapted to use different descriptive statistics of the lognormal distribution to minimize the background errors. The input radiance data is from the AMSU-A and MHS instruments on the NOAA series of spacecraft. To help illustrate how the three retrievals are affected by the change in the distribution we are in the process of creating a new website to show the output from the different retrievals. Here we present initial results from different dynamical situations to show how the tool could be used by forecasters as well as for educators. However, as the new retrieved values are from a non-Gaussian based 1DVAR then they will display non-Gaussian behaviors that need to pass a quality control measure that is consistent with this distribution, and these new measures are presented here along with initial results for checking the retrievals.
Continuous-variable entanglement distillation of non-Gaussian mixed states
International Nuclear Information System (INIS)
Dong Ruifang; Lassen, Mikael; Heersink, Joel; Marquardt, Christoph; Leuchs, Gerd; Filip, Radim; Andersen, Ulrik L.
2010-01-01
Many different quantum-information communication protocols such as teleportation, dense coding, and entanglement-based quantum key distribution are based on the faithful transmission of entanglement between distant location in an optical network. The distribution of entanglement in such a network is, however, hampered by loss and noise that is inherent in all practical quantum channels. Thus, to enable faithful transmission one must resort to the protocol of entanglement distillation. In this paper we present a detailed theoretical analysis and an experimental realization of continuous variable entanglement distillation in a channel that is inflicted by different kinds of non-Gaussian noise. The continuous variable entangled states are generated by exploiting the third order nonlinearity in optical fibers, and the states are sent through a free-space laboratory channel in which the losses are altered to simulate a free-space atmospheric channel with varying losses. We use linear optical components, homodyne measurements, and classical communication to distill the entanglement, and we find that by using this method the entanglement can be probabilistically increased for some specific non-Gaussian noise channels.
Non-Gaussian and nonscale-invariant perturbations from tachyonic preheating in hybrid inflation
Barnaby, Neil; Cline, James M.
2006-05-01
We show that in hybrid inflation it is possible to generate large second-order perturbations in the cosmic microwave background due to the instability of the tachyonic field during preheating. We carefully calculate this effect from the tachyon contribution to the gauge-invariant curvature perturbation, clarifying some confusion in the literature concerning nonlocal terms in the tachyon curvature perturbation; we show explicitly that such terms are absent. We quantitatively compute the non-Gaussianity generated by the tachyon field during the preheating phase and translate the experimental constraints on the nonlinearity parameter fNL into constraints on the parameters of the model. We also show that nonscale-invariant second-order perturbations from the tachyon field with spectral index n=4 can become larger than the inflaton-generated first-order perturbations, leading to stronger constraints than those coming from non-Gaussianity. The width of the excluded region in terms of the logarithm of the dimensionless coupling g, grows linearly with the log of the ratio of the Planck mass to the tachyon VEV, log(Mp/v); hence very large regions are ruled out if the inflationary scale v is small. We apply these results to string-theoretic brane-antibrane inflation, and find a stringent upper bound on the string coupling, gs<10-4.5.
Zhang, Hao; Yang, Jingfa; Zhao, Jiang
The effect of strengthening of interaction between single fluorescent probes and polymer matrix to the probes dynamics is investigated using single molecule fluorescence defocus microscopy. By introducing multiple hydroxyl groups to the fluorescent probes, which builds up hydrogen bonds between the probe and polymer matrix, the dynamics is discovered to be retarded. This is evidenced by the lowering of the frequency of the vibrational modes in the power spectra of the rotation trajectories of individual fluorescent probes, and also by the lowering of population of rotating probes. The results show that by strengthening the probe-matrix interaction, the local dynamics detected by the probes is equivalent to that detected by a bigger probe, due to the enhanced friction between the probe and the polymer matrix. the National Basic Research Program of China (2012CB821500).
International Nuclear Information System (INIS)
Chingangbam, Pravabati; Park, Changbom
2009-01-01
We simulate CMB maps including non-Gaussianity arising from cubic order perturbations of the primordial gravitational potential, characterized by the non-linearity parameter g NL . The maps are used to study the characteristic nature of the resulting non-Gaussian temperature fluctuations. We measure the genus and investigate how it deviates from Gaussian shape as a function of g NL and smoothing scale. We find that the deviation of the non-Gaussian genus curve from the Gaussian one has an antisymmetric, sine function like shape, implying more hot and more cold spots for g NL > 0 and less of both for g NL NL and also exhibits mild increase as the smoothing scale increases. We further study other statistics derived from the genus, namely, the number of hot spots, the number of cold spots, combined number of hot and cold spots and the slope of the genus curve at mean temperature fluctuation. We find that these observables carry signatures of g NL that are clearly distinct from the quadratic order perturbations, encoded in the parameter f NL . Hence they can be very useful tools for distinguishing not only between non-Gaussian temperature fluctuations and Gaussian ones but also between g NL and f NL type non-Gaussianities
Guo, Yongfeng; Shen, Yajun; Tan, Jianguo
2016-09-01
The phenomenon of stochastic resonance (SR) in a piecewise nonlinear model driven by a periodic signal and correlated noises for the cases of a multiplicative non-Gaussian noise and an additive Gaussian white noise is investigated. Applying the path integral approach, the unified colored noise approximation and the two-state model theory, the analytical expression of the signal-to-noise ratio (SNR) is derived. It is found that conventional stochastic resonance exists in this system. From numerical computations we obtain that: (i) As a function of the non-Gaussian noise intensity, the SNR is increased when the non-Gaussian noise deviation parameter q is increased. (ii) As a function of the Gaussian noise intensity, the SNR is decreased when q is increased. This demonstrates that the effect of the non-Gaussian noise on SNR is different from that of the Gaussian noise in this system. Moreover, we further discuss the effect of the correlation time of the non-Gaussian noise, cross-correlation strength, the amplitude and frequency of the periodic signal on SR.
Probing the Locality of Excited States with Linear Algebra.
Etienne, Thibaud
2015-04-14
This article reports a novel theoretical approach related to the analysis of molecular excited states. The strategy introduced here involves gathering two pieces of physical information, coming from Hilbert and direct space operations, into a general, unique quantum mechanical descriptor of electronic transitions' locality. Moreover, the projection of Hilbert and direct space-derived indices in an Argand plane delivers a straightforward way to visually probe the ability of a dye to undergo a long- or short-range charge-transfer. This information can be applied, for instance, to the analysis of the electronic response of families of dyes to light absorption by unveiling the trend of a given push-pull chromophore to increase the electronic cloud polarization magnitude of its main transition with respect to the size extension of its conjugated spacer. We finally demonstrate that all the quantities reported in this article can be reliably approximated by a linear algebraic derivation, based on the contraction of detachment/attachment density matrices from canonical to atomic space. This alternative derivation has the remarkable advantage of a very low computational cost with respect to the previously used numerical integrations, making fast and accurate characterization of large molecular systems' excited states easily affordable.
Directory of Open Access Journals (Sweden)
Tuva Roaldsdatter Hope
2016-08-01
Full Text Available The diffusion weighted imaging (DWI technique enables quantification of water mobility for probing microstructural properties of biological tissue, and has become an effective tool for collecting information about the underlying pathology of cancerous tissue. Measurements using multiple b-values have indicated a bi-exponential signal attenuation, ascribed to fast (high ADC and slow (low ADC diffusion components. In this empirical study, we investigate the properties of the diffusion time (∆ - dependent components of the diffusion-weighted (DW signal in a constant b-value experiment. A Xenograft GBM mouse was imaged using ∆ = 11 ms, 20 ms, 40 ms, 60 ms and b=500-4000 s/mm2 in intervals of 500s/mm2. Data was corrected for EPI distortions and the ∆-dependence on the DW signal was measured within three regions of interest (intermediate- and high-density tumor regions and normal appearing brain tissue regions (NAB. In this empirical study we verify the assumption that the slow decaying component of the DW-signal is non-Gaussian and dependent on ∆, consistent with restricted diffusion of the intracellular space. As the DW-signal as a function of ∆ is specific to restricted diffusion, manipulating ∆ at constant b-value (cb provides a complementary and direct approach for separating the restricted from the hindered diffusion component. Our results show that only tumor tissue signal of our data demonstrate ∆-dependence, based on a bi-exponential model with a restricted diffusion component, we successfully estimated the restricted ADC, signal volume fraction and cell size within each tumor ROI.
Bugaev, Edgar; Klimai, Peter
2012-05-01
We consider the process of primordial black hole (PBH) formation originated from primordial curvature perturbations produced during waterfall transition (with tachyonic instability), at the end of hybrid inflation. It is known that in such inflation models, rather large values of curvature perturbation amplitudes can be reached, which can potentially cause a significant PBH production in the early Universe. The probability distributions of density perturbation amplitudes in this case can be strongly non-Gaussian, which requires a special treatment. We calculated PBH abundances and PBH mass spectra for the model and analyzed their dependence on model parameters. We obtained the constraints on the parameters of the inflationary potential, using the available limits on βPBH.
Curvature perturbation spectra from waterfall transition, black hole constraints and non-Gaussianity
Energy Technology Data Exchange (ETDEWEB)
Bugaev, Edgar; Klimai, Peter, E-mail: bugaev@pcbai10.inr.ruhep.ru, E-mail: pklimai@gmail.com [Institute for Nuclear Research, Russian Academy of Sciences, 60th October Anniversary Prospect 7a, 117312 Moscow (Russian Federation)
2011-11-01
We carried out numerical calculations of a contribution of the waterfall field to the primordial curvature perturbation (on uniform density hypersurfaces) ζ, which is produced during waterfall transition in hybrid inflation scenario. The calculation is performed for a broad interval of values of the model parameters. We show that there is a strong growth of amplitudes of the curvature perturbation spectrum in the limit when the bare mass-squared of the waterfall field becomes comparable with the square of Hubble parameter. We show that in this limit the primordial black hole constraints on the curvature perturbations must be taken into account. It is shown that, in the same limit, peak values of the curvature perturbation spectra are far beyond horizon, and the spectra are strongly non-Gaussian.
Curvature perturbation spectra from waterfall transition, black hole constraints and non-Gaussianity
International Nuclear Information System (INIS)
Bugaev, Edgar; Klimai, Peter
2011-01-01
We carried out numerical calculations of a contribution of the waterfall field to the primordial curvature perturbation (on uniform density hypersurfaces) ζ, which is produced during waterfall transition in hybrid inflation scenario. The calculation is performed for a broad interval of values of the model parameters. We show that there is a strong growth of amplitudes of the curvature perturbation spectrum in the limit when the bare mass-squared of the waterfall field becomes comparable with the square of Hubble parameter. We show that in this limit the primordial black hole constraints on the curvature perturbations must be taken into account. It is shown that, in the same limit, peak values of the curvature perturbation spectra are far beyond horizon, and the spectra are strongly non-Gaussian
Non-Gaussianity and statistical anisotropy from vector field populated inflationary models
Dimastrogiovanni, Emanuela; Matarrese, Sabino; Riotto, Antonio
2010-01-01
We present a review of vector field models of inflation and, in particular, of the statistical anisotropy and non-Gaussianity predictions of models with SU(2) vector multiplets. Non-Abelian gauge groups introduce a richer amount of predictions compared to the Abelian ones, mostly because of the presence of vector fields self-interactions. Primordial vector fields can violate isotropy leaving their imprint in the comoving curvature fluctuations zeta at late times. We provide the analytic expressions of the correlation functions of zeta up to fourth order and an analysis of their amplitudes and shapes. The statistical anisotropy signatures expected in these models are important and, potentially, the anisotropic contributions to the bispectrum and the trispectrum can overcome the isotropic parts.
Non-Gaussian Systems Control Performance Assessment Based on Rational Entropy
Directory of Open Access Journals (Sweden)
Jinglin Zhou
2018-05-01
Full Text Available Control loop Performance Assessment (CPA plays an important role in system operations. Stochastic statistical CPA index, such as a minimum variance controller (MVC-based CPA index, is one of the most widely used CPA indices. In this paper, a new minimum entropy controller (MEC-based CPA method of linear non-Gaussian systems is proposed. In this method, probability density function (PDF and rational entropy (RE are respectively used to describe the characteristics and the uncertainty of random variables. To better estimate the performance benchmark, an improved EDA algorithm, which is used to estimate the system parameters and noise PDF, is given. The effectiveness of the proposed method is illustrated through case studies on an ARMAX system.
International Nuclear Information System (INIS)
Brown, M.J.; Arya, S.P.; Snyder, W.H.
1993-01-01
The vertical diffusion of a passive tracer released from surface and elevated sources in a neutrally stratified boundary layer has been studied by comparing field and laboratory experiments with a non-Gaussian K-theory model that assumes power-law profiles for the mean velocity and vertical eddy diffusivity. Several important differences between model predictions and experimental data were discovered: (1) the model overestimated ground-level concentrations from surface and elevated releases at distances beyond the peak concentration; (2) the model overpredicted vertical mixing near elevated sources, especially in the upward direction; (3) the model-predicted exponent α in the exponential vertical concentration profile for a surface release [bar C(z)∝ exp(-z α )] was smaller than the experimentally measured exponent. Model closure assumptions and experimental short-comings are discussed in relation to their probable effect on model predictions and experimental measurements. 42 refs., 13 figs., 3 tabs
Partial summations of stationary sequences of non-Gaussian random variables
DEFF Research Database (Denmark)
Mohr, Gunnar; Ditlevsen, Ove Dalager
1996-01-01
The distribution of the sum of a finite number of identically distributed random variables is in many cases easily determined given that the variables are independent. The moments of any order of the sum can always be expressed by the moments of the single term without computational problems...... of convergence of the distribution of a sum (or an integral) of mutually dependent random variables to the Gaussian distribution. The paper is closely related to the work in Ditlevsen el al. [Ditlevsen, O., Mohr, G. & Hoffmeyer, P. Integration of non-Gaussian fields. Prob. Engng Mech 11 (1996) 15-23](2)....... lognormal variables or polynomials of standard Gaussian variables. The dependency structure is induced by specifying the autocorrelation structure of the sequence of standard Gaussian variables. Particularly useful polynomials are the Winterstein approximations that distributionally fit with non...
On the generation of a non-gaussian curvature perturbation during preheating
Energy Technology Data Exchange (ETDEWEB)
Kohri, Kazunori; Lyth, David H. [Department of Physics, Lancaster University, Lancaster LA1 4YB (United Kingdom); Valenzuela-Toledo, Cesar A., E-mail: k.kohri@lancaster.ac.uk, E-mail: d.lyth@lancaster.ac.uk, E-mail: cavalto@ciencias.uis.edu.co [Escuela de Física, Universidad Industrial de Santander, Ciudad Universitaria, Bucaramanga (Colombia)
2010-02-01
The perturbation of a light field might affect preheating and hence generate a contribution to the spectrum and non-gaussianity of the curvature perturbation ζ. The field might appear directly in the preheating model (curvaton-type preheating) or indirectly through its effect on a mass or coupling (modulated preheating). We give general expressions for ζ based on the δN formula, and apply them to the cases of quadratic and quartic chaotic inflation. For the quadratic case, curvaton-type preheating is ineffective in contributing to ζ, but modulated preheating can be effective. For quartic inflation, curvaton-type preheating may be effective but the usual δN formalism has to be modified. We see under what circumstances the recent numerical simulation of Bond et al. [0903.3407] may be enough to provide a rough estimate for this case.
On the generation of a non-gaussian curvature perturbation during preheating
International Nuclear Information System (INIS)
Kohri, Kazunori; Lyth, David H.; Valenzuela-Toledo, Cesar A.
2010-01-01
The perturbation of a light field might affect preheating and hence generate a contribution to the spectrum and non-gaussianity of the curvature perturbation ζ. The field might appear directly in the preheating model (curvaton-type preheating) or indirectly through its effect on a mass or coupling (modulated preheating). We give general expressions for ζ based on the δN formula, and apply them to the cases of quadratic and quartic chaotic inflation. For the quadratic case, curvaton-type preheating is ineffective in contributing to ζ, but modulated preheating can be effective. For quartic inflation, curvaton-type preheating may be effective but the usual δN formalism has to be modified. We see under what circumstances the recent numerical simulation of Bond et al. [0903.3407] may be enough to provide a rough estimate for this case
'Finite' non-Gaussianities and tensor-scalar ratio in large volume Swiss-cheese compactifications
International Nuclear Information System (INIS)
Misra, Aalok; Shukla, Pramod
2009-01-01
Developing on the ideas of (Section 4 of) [A. Misra, P. Shukla, Moduli stabilization, large-volume dS minimum without anti-D3-branes, (non-)supersymmetric black hole attractors and two-parameter Swiss cheese Calabi-Yau's, Nucl. Phys. B 799 (2008) 165-198, (arXiv: 0707.0105)] and [A. Misra, P. Shukla, Large volume axionic Swiss-cheese inflation, Nucl. Phys. B 800 (2008) 384-400, (arXiv: 0712.1260 [hep-th])] and using the formalisms of [S. Yokoyama, T. Suyama, T. Tanaka, Primordial non-Gaussianity in multi-scalar slow-roll inflation, (arXiv: 0705.3178 [astro-ph]); S. Yokoyama, T. Suyama, T. Tanaka, Primordial non-Gaussianity in multi-scalar inflation, Phys. Rev. D 77 (2008) 083511, (arXiv: 0711.2920 [astro-ph])], after inclusion of perturbative and non-perturbative α' corrections to the Kaehler potential and (D1- and D3-)instanton generated superpotential, we show the possibility of getting finite values for the non-linear parameter f NL while looking for non-Gaussianities in type IIB compactifications on orientifolds of the Swiss cheese Calabi-Yau WCP 4 [1,1,1,6,9] in the L(arge) V(olume) S(cenarios) limit. We show the same in two contexts. First is multi-field slow-roll inflation with D3-instanton contribution coming from a large number of multiple wrappings of a single (Euclidean) D3-brane around the 'small' divisor yielding f NL ∼O(1). The second is when the slow-roll conditions are violated and for the number of the aforementioned D3-instanton wrappings being of O(1) but more than one, yielding f NL ∼O(1). Based on general arguments not specific to our (string-theory) set-up, we argue that requiring curvature perturbations not to grow at horizon crossing and at super-horizon scales, automatically picks out hybrid inflationary scenarios which in our set up can yield f NL ∼O(1) and tensor-scalar ratio of O(10 -2 ). For all our calculations, the world-sheet instanton contributions to the Kaehler potential coming from the non-perturbative α ' corrections
Non-Gaussian information from weak lensing data via deep learning
Gupta, Arushi; Matilla, José Manuel Zorrilla; Hsu, Daniel; Haiman, Zoltán
2018-05-01
Weak lensing maps contain information beyond two-point statistics on small scales. Much recent work has tried to extract this information through a range of different observables or via nonlinear transformations of the lensing field. Here we train and apply a two-dimensional convolutional neural network to simulated noiseless lensing maps covering 96 different cosmological models over a range of {Ωm,σ8} . Using the area of the confidence contour in the {Ωm,σ8} plane as a figure of merit, derived from simulated convergence maps smoothed on a scale of 1.0 arcmin, we show that the neural network yields ≈5 × tighter constraints than the power spectrum, and ≈4 × tighter than the lensing peaks. Such gains illustrate the extent to which weak lensing data encode cosmological information not accessible to the power spectrum or even other, non-Gaussian statistics such as lensing peaks.
A Robust Non-Gaussian Data Assimilation Method for Highly Non-Linear Models
Directory of Open Access Journals (Sweden)
Elias D. Nino-Ruiz
2018-03-01
Full Text Available In this paper, we propose an efficient EnKF implementation for non-Gaussian data assimilation based on Gaussian Mixture Models and Markov-Chain-Monte-Carlo (MCMC methods. The proposed method works as follows: based on an ensemble of model realizations, prior errors are estimated via a Gaussian Mixture density whose parameters are approximated by means of an Expectation Maximization method. Then, by using an iterative method, observation operators are linearized about current solutions and posterior modes are estimated via a MCMC implementation. The acceptance/rejection criterion is similar to that of the Metropolis-Hastings rule. Experimental tests are performed on the Lorenz 96 model. The results show that the proposed method can decrease prior errors by several order of magnitudes in a root-mean-square-error sense for nearly sparse or dense observational networks.
Fault Detection for Non-Gaussian Stochastic Systems with Time-Varying Delay
Directory of Open Access Journals (Sweden)
Tao Li
2013-01-01
Full Text Available Fault detection (FD for non-Gaussian stochastic systems with time-varying delay is studied. The available information for the addressed problem is the input and the measured output probability density functions (PDFs of the system. In this framework, firstly, by constructing an augmented Lyapunov functional, which involves some slack variables and a tuning parameter, a delay-dependent condition for the existence of FD observer is derived in terms of linear matrix inequality (LMI and the fault can be detected through a threshold. Secondly, in order to improve the detection sensitivity performance, the optimal algorithm is applied to minimize the threshold value. Finally, paper-making process example is given to demonstrate the applicability of the proposed approach.
Manifestly non-Gaussian fluctuations in superconductor-normal metal tunnel nanostructures
Energy Technology Data Exchange (ETDEWEB)
Laakso, Matti [Institut fuer Theorie der Statistischen Physik, RWTH Aachen University, Aachen (Germany); Low Temperature Laboratory, Aalto University, Espoo (Finland); Heikkilae, Tero [Low Temperature Laboratory, Aalto University, Espoo (Finland); Nazarov, Yuli [Kavli Institute of Nanoscience, Delft University of Technology, Delft (Netherlands)
2013-07-01
Recently, temperature fluctuation statistics has been studied in non-interacting islands and overheated single-electron transistors. We propose a mesoscopic setup which exhibits strong and manifestly non-Gaussian fluctuations of energy and temperature when suitably driven out of equilibrium. The setup consists of a normal metal island (N) coupled by tunnel junctions (I) to two superconducting leads (S), forming a SINIS structure, and is biased near the threshold voltage for quasiparticle tunneling, eV ∼ 2Δ. The fluctuations can be measured by monitoring the time-dependent electric current through the system, which makes the setup suitable for the realization of feedback schemes which allow to stabilize the temperature to the desired value.
A generalized non-Gaussian consistency relation for single field inflation
Bravo, Rafael; Mooij, Sander; Palma, Gonzalo A.; Pradenas, Bastián
2018-05-01
We show that a perturbed inflationary spacetime, driven by a canonical single scalar field, is invariant under a special class of coordinate transformations together with a field reparametrization of the curvature perturbation in co-moving gauge. This transformation may be used to derive the squeezed limit of the 3-point correlation function of the co-moving curvature perturbations valid in the case that these do not freeze after horizon crossing. This leads to a generalized version of Maldacena's non-Gaussian consistency relation in the sense that the bispectrum squeezed limit is completely determined by spacetime diffeomorphisms. Just as in the case of the standard consistency relation, this result may be understood as the consequence of how long-wavelength modes modulate those of shorter wavelengths. This relation allows one to derive the well known violation to the consistency relation encountered in ultra slow-roll, where curvature perturbations grow exponentially after horizon crossing.
Effect of primordial non-Gaussianities on galaxy clusters scaling relations
Trindade, A. M. M.; da Silva, Antonio
2017-07-01
Galaxy clusters are a valuable source of cosmological information. Their formation and evolution depends on the underlying cosmology and on the statistical nature of the primordial density fluctuations. Here we investigate the impact of primordial non-Gaussianities (PNG) on the scaling properties of galaxy clusters. We performed a series of hydrodynamic N-body simulations featuring adiabatic gas physics and different levels of non-Gaussianity within the Λ cold dark matter framework. We focus on the T-M, S-M, Y-M and YX-M scalings relating the total cluster mass with temperature, entropy and Sunyaev-Zeld'ovich integrated pressure that reflect the thermodynamic state of the intracluster medium. Our results show that PNG have an impact on cluster scalings laws. The scalings mass power-law indexes are almost unaffected by the existence of PNG, but the amplitude and redshift evolution of their normalizations are clearly affected. Changes in the Y-M and YX-M normalizations are as high as 22 per cent and 16 per cent when fNL varies from -500 to 500, respectively. Results are consistent with the view that positive/negative fNL affect cluster profiles due to an increase/decrease of cluster concentrations. At low values of fNL, as suggested by present Planck constraints on a scale invariant fNL, the impact on the scaling normalizations is only a few per cent. However, if fNL varies with scale, PNG may have larger amplitudes at clusters scales; thus, our results suggest that PNG should be taken into account when cluster data are used to infer or forecast cosmological parameters from existing or future cluster surveys.
International Nuclear Information System (INIS)
Haven, Kyle; Majda, Andrew; Abramov, Rafail
2005-01-01
Many situations in complex systems require quantitative estimates of the lack of information in one probability distribution relative to another. In short term climate and weather prediction, examples of these issues might involve the lack of information in the historical climate record compared with an ensemble prediction, or the lack of information in a particular Gaussian ensemble prediction strategy involving the first and second moments compared with the non-Gaussian ensemble itself. The relative entropy is a natural way to quantify the predictive utility in this information, and recently a systematic computationally feasible hierarchical framework has been developed. In practical systems with many degrees of freedom, computational overhead limits ensemble predictions to relatively small sample sizes. Here the notion of predictive utility, in a relative entropy framework, is extended to small random samples by the definition of a sample utility, a measure of the unlikeliness that a random sample was produced by a given prediction strategy. The sample utility is the minimum predictability, with a statistical level of confidence, which is implied by the data. Two practical algorithms for measuring such a sample utility are developed here. The first technique is based on the statistical method of null-hypothesis testing, while the second is based upon a central limit theorem for the relative entropy of moment-based probability densities. These techniques are tested on known probability densities with parameterized bimodality and skewness, and then applied to the Lorenz '96 model, a recently developed 'toy' climate model with chaotic dynamics mimicking the atmosphere. The results show a detection of non-Gaussian tendencies of prediction densities at small ensemble sizes with between 50 and 100 members, with a 95% confidence level
Energy Technology Data Exchange (ETDEWEB)
Wang, Yuan-Mei; Li, Jun-Gang, E-mail: jungl@bit.edu.cn; Zou, Jian
2017-06-15
Highlights: • Adaptive measurement strategy is used to detect the presence of a magnetic field. • Gaussian Ornstein–Uhlenbeck noise and non-Gaussian noise have been considered. • Weaker magnetic fields may be more easily detected than some stronger ones. - Abstract: By using the adaptive measurement method we study how to detect whether a weak magnetic field is actually present or not under Gaussian noise and non-Gaussian noise. We find that the adaptive measurement method can effectively improve the detection accuracy. For the case of Gaussian noise, we find the stronger the magnetic field strength, the easier for us to detect the magnetic field. Counterintuitively, for non-Gaussian noise, some weaker magnetic fields are more likely to be detected rather than some stronger ones. Finally, we give a reasonable physical interpretation.
International Nuclear Information System (INIS)
Guo Yongfeng; Xu Wei; Li Dongxi; Xie Wenxian
2008-01-01
A stochastic dissipative dynamical system driven by non-Gaussian noise is investigated. A general approximate Fokker-Planck equation of the system is derived through a path-integral approach. Based on the definition of Shannon's information entropy, the exact time dependence of entropy flux and entropy production of the system is calculated both in the absence and in the presence of non-equilibrium constraint. The present calculation can be used to interpret the interplay of the dissipative constant and non-Gaussian noise on the entropy flux and entropy production
Xiang, Shao-Hua; Wen, Wei; Zhao, Yu-Jing; Song, Ke-Hui
2018-04-01
We study the properties of the cumulants of multimode boson operators and introduce the phase-averaged quadrature cumulants as the measure of the non-Gaussianity of multimode quantum states. Using this measure, we investigate the non-Gaussianity of two classes of two-mode non-Gaussian states: photon-number entangled states and entangled coherent states traveling in a bosonic memory quantum channel. We show that such a channel can skew the distribution of two-mode quadrature variables, giving rise to a strongly non-Gaussian correlation. In addition, we provide a criterion to determine whether the distributions of these states are super- or sub-Gaussian.
Theoretical analysis of non-Gaussian heterogeneity effects on subsurface flow and transport
Riva, Monica; Guadagnini, Alberto; Neuman, Shlomo P.
2017-04-01
Much of the stochastic groundwater literature is devoted to the analysis of flow and transport in Gaussian or multi-Gaussian log hydraulic conductivity (or transmissivity) fields, Y(x)=ln\\func K(x) (x being a position vector), characterized by one or (less frequently) a multiplicity of spatial correlation scales. Yet Y and many other variables and their (spatial or temporal) increments, ΔY, are known to be generally non-Gaussian. One common manifestation of non-Gaussianity is that whereas frequency distributions of Y often exhibit mild peaks and light tails, those of increments ΔY are generally symmetric with peaks that grow sharper, and tails that become heavier, as separation scale or lag between pairs of Y values decreases. A statistical model that captures these disparate, scale-dependent distributions of Y and ΔY in a unified and consistent manner has been recently proposed by us. This new "generalized sub-Gaussian (GSG)" model has the form Y(x)=U(x)G(x) where G(x) is (generally, but not necessarily) a multiscale Gaussian random field and U(x) is a nonnegative subordinator independent of G. The purpose of this paper is to explore analytically, in an elementary manner, lead-order effects that non-Gaussian heterogeneity described by the GSG model have on the stochastic description of flow and transport. Recognizing that perturbation expansion of hydraulic conductivity K=eY diverges when Y is sub-Gaussian, we render the expansion convergent by truncating Y's domain of definition. We then demonstrate theoretically and illustrate by way of numerical examples that, as the domain of truncation expands, (a) the variance of truncated Y (denoted by Yt) approaches that of Y and (b) the pdf (and thereby moments) of Yt increments approach those of Y increments and, as a consequence, the variogram of Yt approaches that of Y. This in turn guarantees that perturbing Kt=etY to second order in σYt (the standard deviation of Yt) yields results which approach those we obtain
Efficient atom localization via probe absorption in an inverted-Y atomic system
Wu, Jianchun; Wu, Bo; Mao, Jiejian
2018-06-01
The behaviour of atom localization in an inverted-Y atomic system is theoretically investigated. For the atoms interacting with a weak probe field and several orthogonal standing-wave fields, their position information can be obtained by measuring the probe absorption. Compared with the traditional scheme, we couple the probe field to the transition between the middle and top levels. It is found that the probe absorption sensitively depends on the detuning and strength of the relevant light fields. Remarkably, the atom can be localized at a particular position in the standing-wave fields by coupling a microwave field to the transition between the two ground levels.
ENSO's non-stationary and non-Gaussian character: the role of climate shifts
Boucharel, J.; Dewitte, B.; Garel, B.; Du Penhoat, Y.
2009-07-01
El Niño Southern Oscillation (ENSO) is the dominant mode of climate variability in the Pacific, having socio-economic impacts on surrounding regions. ENSO exhibits significant modulation on decadal to inter-decadal time scales which is related to changes in its characteristics (onset, amplitude, frequency, propagation, and predictability). Some of these characteristics tend to be overlooked in ENSO studies, such as its asymmetry (the number and amplitude of warm and cold events are not equal) and the deviation of its statistics from those of the Gaussian distribution. These properties could be related to the ability of the current generation of coupled models to predict ENSO and its modulation. Here, ENSO's non-Gaussian nature and asymmetry are diagnosed from in situ data and a variety of models (from intermediate complexity models to full-physics coupled general circulation models (CGCMs)) using robust statistical tools initially designed for financial mathematics studies. In particular α-stable laws are used as theoretical background material to measure (and quantify) the non-Gaussian character of ENSO time series and to estimate the skill of ``naïve'' statistical models in producing deviation from Gaussian laws and asymmetry. The former are based on non-stationary processes dominated by abrupt changes in mean state and empirical variance. It is shown that the α-stable character of ENSO may result from the presence of climate shifts in the time series. Also, cool (warm) periods are associated with ENSO statistics having a stronger (weaker) tendency towards Gaussianity and lower (greater) asymmetry. This supports the hypothesis of ENSO being rectified by changes in mean state through nonlinear processes. The relationship between changes in mean state and nonlinearity (skewness) is further investigated both in the Zebiak and Cane (1987)'s model and the models of the Intergovernmental Panel for Climate Change (IPCC). Whereas there is a clear relationship in all
Directory of Open Access Journals (Sweden)
Carlos A. L. Pires
2017-01-01
Full Text Available We propose an expansion of multivariate time-series data into maximally independent source subspaces. The search is made among rotations of prewhitened data which maximize non-Gaussianity of candidate sources. We use a tensorial invariant approximation of the multivariate negentropy in terms of a linear combination of squared coskewness and cokurtosis. By solving a high-order singular value decomposition problem, we extract the axes associated with most non-Gaussianity. Moreover, an estimate of the Gaussian subspace is provided by the trailing singular vectors. The independent subspaces are obtained through the search of “quasi-independent” components within the estimated non-Gaussian subspace, followed by the identification of groups with significant joint negentropies. Sources result essentially from the coherency of extremes of the data components. The method is then applied to the global sea surface temperature anomalies, equatorward of 65°, after being tested with non-Gaussian surrogates consistent with the data anomalies. The main emerging independent components and subspaces, supposedly generated by independent forcing, include different variability modes, namely, The East-Pacific, the Central Pacific, and the Atlantic Niños, the Atlantic Multidecadal Oscillation, along with the subtropical dipoles in the Indian, South Pacific, and South-Atlantic oceans. Benefits and usefulness of independent subspaces are then discussed.
DEFF Research Database (Denmark)
Andreasen, Martin Møller; Christensen, Bent Jesper
This paper suggests a new and easy approach to estimate linear and non-linear dynamic term structure models with latent factors. We impose no distributional assumptions on the factors and they may therefore be non-Gaussian. The novelty of our approach is to use many observables (yields or bonds p...
Czech Academy of Sciences Publication Activity Database
Jeon, J. H.; Javanainen, M.; Martinez-Seara, Hector; Metzler, R.; Vattulainen, I.
2016-01-01
Roč. 6, č. 2 (2016), č. článku 021006. ISSN 2160-3308 Institutional support: RVO:61388963 Keywords : protein crowding * membranes * simulations * diffusion * non-Gaussian anomalous diffusion Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 12.789, year: 2016 http://journals.aps.org/prx/abstract/10.1103/PhysRevX.6.021006
International Nuclear Information System (INIS)
Olejnik, S.
1989-01-01
It is shown that the leading and next-to-leading non-gaussian effects have a minor inlfuence on the instanton density for the double-well potential: it is slightly increased, contrary to the claims of other authors. We point out a connection to recent quantitative studies of topological effects in gauge theories. (orig.)
Czech Academy of Sciences Publication Activity Database
Lamperti, M.; Allevi, A.; Bondani, M.; Machulka, R.; Michálek, Václav; Haderka, O.; Peřina Jr., J.
2014-01-01
Roč. 12, č. 2 (2014), "1461017-1"-"1461017-7" ISSN 0219-7499 R&D Projects: GA ČR GAP205/12/0382 Institutional support: RVO:68378271 Keywords : quantum state engineering and measurements * parametric down-conversion * photodetectors * sub-Poissonian statistics * non-Gaussianity Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.877, year: 2014
Topology in two dimensions. IV - CDM models with non-Gaussian initial conditions
Coles, Peter; Moscardini, Lauro; Plionis, Manolis; Lucchin, Francesco; Matarrese, Sabino; Messina, Antonio
1993-02-01
The results of N-body simulations with both Gaussian and non-Gaussian initial conditions are used here to generate projected galaxy catalogs with the same selection criteria as the Shane-Wirtanen counts of galaxies. The Euler-Poincare characteristic is used to compare the statistical nature of the projected galaxy clustering in these simulated data sets with that of the observed galaxy catalog. All the models produce a topology dominated by a meatball shift when normalized to the known small-scale clustering properties of galaxies. Models characterized by a positive skewness of the distribution of primordial density perturbations are inconsistent with the Lick data, suggesting problems in reconciling models based on cosmic textures with observations. Gaussian CDM models fit the distribution of cell counts only if they have a rather high normalization but possess too low a coherence length compared with the Lick counts. This suggests that a CDM model with extra large scale power would probably fit the available data.
Self-focusing of a non-Gaussian laser mode in a dense plasma
International Nuclear Information System (INIS)
Nayyar, V.P.
1978-01-01
This paper presents a study of the self-focusing of a high-power non-Gaussian laser beam operating in TEM 01 mode in a strongly ionized plasma. The nonlinearity in the dielectric constant is caused by the nonuniform redistribution of carriers due to their inhomogeneous heating by the laser beam having transverse variation of intensity along its wave front. It is found that when the power of the beam exceeds the critical power, focusing effects are observed in the Y direction, whereas divergence of the beam takes place in the X direction. In the reverse case (when P 2 first increases in the Y direction, after penetrating a certain depth it reaches a broadened maxima and then starts decreasing with the distance of propagation inside the medium. The beam continues diverging in the X direction. It has also been found that absorption brings about a reduction in the extent of self-focusing. When the absorption length is less than the self-focusing length appreciable self-focusing does not take place
Characterisation of random Gaussian and non-Gaussian stress processes in terms of extreme responses
Directory of Open Access Journals (Sweden)
Colin Bruno
2015-01-01
Full Text Available In the field of military land vehicles, random vibration processes generated by all-terrain wheeled vehicles in motion are not classical stochastic processes with a stationary and Gaussian nature. Non-stationarity of processes induced by the variability of the vehicle speed does not form a major difficulty because the designer can have good control over the vehicle speed by characterising the histogram of instantaneous speed of the vehicle during an operational situation. Beyond this non-stationarity problem, the hard point clearly lies in the fact that the random processes are not Gaussian and are generated mainly by the non-linear behaviour of the undercarriage and the strong occurrence of shocks generated by roughness of the terrain. This non-Gaussian nature is expressed particularly by very high flattening levels that can affect the design of structures under extreme stresses conventionally acquired by spectral approaches, inherent to Gaussian processes and based essentially on spectral moments of stress processes. Due to these technical considerations, techniques for characterisation of random excitation processes generated by this type of carrier need to be changed, by proposing innovative characterisation methods based on time domain approaches as described in the body of the text rather than spectral domain approaches.
EVOLUTION OF THE MAGNETIC FIELD LINE DIFFUSION COEFFICIENT AND NON-GAUSSIAN STATISTICS
Energy Technology Data Exchange (ETDEWEB)
Snodin, A. P. [Department of Mathematics, Faculty of Applied Science, King Mongkut’s University of Technology North Bangkok, Bangkok 10800 (Thailand); Ruffolo, D. [Department of Physics, Faculty of Science, Mahidol University, Bangkok 10400 (Thailand); Matthaeus, W. H. [Bartol Research Institute and Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States)
2016-08-20
The magnetic field line random walk (FLRW) plays an important role in the transport of energy and particles in turbulent plasmas. For magnetic fluctuations that are transverse or almost transverse to a large-scale mean magnetic field, theories describing the FLRW usually predict asymptotic diffusion of magnetic field lines perpendicular to the mean field. Such theories often depend on the assumption that one can relate the Lagrangian and Eulerian statistics of the magnetic field via Corrsin’s hypothesis, and additionally take the distribution of magnetic field line displacements to be Gaussian. Here we take an ordinary differential equation (ODE) model with these underlying assumptions and test how well it describes the evolution of the magnetic field line diffusion coefficient in 2D+slab magnetic turbulence, by comparisons to computer simulations that do not involve such assumptions. In addition, we directly test the accuracy of the Corrsin approximation to the Lagrangian correlation. Over much of the studied parameter space we find that the ODE model is in fairly good agreement with computer simulations, in terms of both the evolution and asymptotic values of the diffusion coefficient. When there is poor agreement, we show that this can be largely attributed to the failure of Corrsin’s hypothesis rather than the assumption of Gaussian statistics of field line displacements. The degree of non-Gaussianity, which we measure in terms of the kurtosis, appears to be an indicator of how well Corrsin’s approximation works.
De Simone, Andrea; Riotto, Antonio
2011-01-01
The excursion set theory, where density perturbations evolve stochastically with the smoothing scale, provides a method for computing the dark matter halo mass function. The computation of the mass function is mapped into the so-called first-passage time problem in the presence of a moving barrier. The excursion set theory is also a powerful formalism to study other properties of dark matter halos such as halo bias, accretion rate, formation time, merging rate and the formation history of halos. This is achieved by computing conditional probabilities with non-trivial initial conditions, and the conditional two-barrier first-crossing rate. In this paper we use the recently-developed path integral formulation of the excursion set theory to calculate analytically these conditional probabilities in the presence of a generic moving barrier, including the one describing the ellipsoidal collapse, and for both Gaussian and non-Gaussian initial conditions. The non-Markovianity of the random walks induced by non-Gaussi...
Energy Technology Data Exchange (ETDEWEB)
Kenfack, Lionel Tenemeza, E-mail: kenfacklionel300@gmail.com [Mesoscopic and Multilayer Structure Laboratory, Department of Physics, Faculty of Science, University of Dschang, PO Box: 67 Dschang (Cameroon); Tchoffo, Martin; Fai, Lukong Cornelius [Mesoscopic and Multilayer Structure Laboratory, Department of Physics, Faculty of Science, University of Dschang, PO Box: 67 Dschang (Cameroon); Fouokeng, Georges Collince [Mesoscopic and Multilayer Structure Laboratory, Department of Physics, Faculty of Science, University of Dschang, PO Box: 67 Dschang (Cameroon); Laboratoire de Génie des Matériaux, Pôle Recherche-Innovation-Entrepreneuriat (PRIE), Institut Universitaire de la Côte, BP 3001 Douala (Cameroon)
2017-04-15
We address the entanglement dynamics of a three-qubit system interacting with a classical fluctuating environment described either by a Gaussian or non-Gaussian noise in three different configurations namely: common, independent and mixed environments. Specifically, we focus on the Ornstein-Uhlenbeck (OU) noise and the random telegraph noise (RTN). The qubits are prepared in a state composed of a Greenberger-Horne-Zeilinger (GHZ) and a W state. With the help of the tripartite negativity, we show that the entanglement evolution is not only affected by the type of system-environment coupling but also by the kind and the memory properties of the considered noise. We also compared the dynamics induced by the two kinds of noise and we find that even if both noises have a Lorentzian spectrum, the effects of the OU noise cannot be in a simple way deduced from those of the RTN and vice-versa. In addition, we show that the entanglement can be indefinitely preserved when the qubits are coupled to the environmental noise in a common environment (CE). Finally, the presence or absence of peculiar phenomena such as entanglement revivals (ER) and entanglement sudden death (ESD) is observed.
International Nuclear Information System (INIS)
Kenfack, Lionel Tenemeza; Tchoffo, Martin; Fai, Lukong Cornelius; Fouokeng, Georges Collince
2017-01-01
We address the entanglement dynamics of a three-qubit system interacting with a classical fluctuating environment described either by a Gaussian or non-Gaussian noise in three different configurations namely: common, independent and mixed environments. Specifically, we focus on the Ornstein-Uhlenbeck (OU) noise and the random telegraph noise (RTN). The qubits are prepared in a state composed of a Greenberger-Horne-Zeilinger (GHZ) and a W state. With the help of the tripartite negativity, we show that the entanglement evolution is not only affected by the type of system-environment coupling but also by the kind and the memory properties of the considered noise. We also compared the dynamics induced by the two kinds of noise and we find that even if both noises have a Lorentzian spectrum, the effects of the OU noise cannot be in a simple way deduced from those of the RTN and vice-versa. In addition, we show that the entanglement can be indefinitely preserved when the qubits are coupled to the environmental noise in a common environment (CE). Finally, the presence or absence of peculiar phenomena such as entanglement revivals (ER) and entanglement sudden death (ESD) is observed.
Scanning probes for new energy materials: probing local structure and function
Balke, N.; Bonnell, D.; Ginger, D.S.; Kemerink, M.
2012-01-01
The design and control of materials properties, often at the nanoscale, are the foundation of many new strategies for energy generation, storage, and efficiency. Scanning probe microscopy (SPM) has evolved into a very large toolbox for the characterization of properties spanning size scales from
Inverse modelling of atmospheric tracers: non-Gaussian methods and second-order sensitivity analysis
Directory of Open Access Journals (Sweden)
M. Bocquet
2008-02-01
Full Text Available For a start, recent techniques devoted to the reconstruction of sources of an atmospheric tracer at continental scale are introduced. A first method is based on the principle of maximum entropy on the mean and is briefly reviewed here. A second approach, which has not been applied in this field yet, is based on an exact Bayesian approach, through a maximum a posteriori estimator. The methods share common grounds, and both perform equally well in practice. When specific prior hypotheses on the sources are taken into account such as positivity, or boundedness, both methods lead to purposefully devised cost-functions. These cost-functions are not necessarily quadratic because the underlying assumptions are not Gaussian. As a consequence, several mathematical tools developed in data assimilation on the basis of quadratic cost-functions in order to establish a posteriori analysis, need to be extended to this non-Gaussian framework. Concomitantly, the second-order sensitivity analysis needs to be adapted, as well as the computations of the averaging kernels of the source and the errors obtained in the reconstruction. All of these developments are applied to a real case of tracer dispersion: the European Tracer Experiment [ETEX]. Comparisons are made between a least squares cost function (similar to the so-called 4D-Var approach and a cost-function which is not based on Gaussian hypotheses. Besides, the information content of the observations which is used in the reconstruction is computed and studied on the application case. A connection with the degrees of freedom for signal is also established. As a by-product of these methodological developments, conclusions are drawn on the information content of the ETEX dataset as seen from the inverse modelling point of view.
International Nuclear Information System (INIS)
Mandel, Kaisey S.; Kirshner, Robert P.; Foley, Ryan J.
2014-01-01
We investigate the statistical dependence of the peak intrinsic colors of Type Ia supernovae (SNe Ia) on their expansion velocities at maximum light, measured from the Si II λ6355 spectral feature. We construct a new hierarchical Bayesian regression model, accounting for the random effects of intrinsic scatter, measurement error, and reddening by host galaxy dust, and implement a Gibbs sampler and deviance information criteria to estimate the correlation. The method is applied to the apparent colors from BVRI light curves and Si II velocity data for 79 nearby SNe Ia. The apparent color distributions of high-velocity (HV) and normal velocity (NV) supernovae exhibit significant discrepancies for B – V and B – R, but not other colors. Hence, they are likely due to intrinsic color differences originating in the B band, rather than dust reddening. The mean intrinsic B – V and B – R color differences between HV and NV groups are 0.06 ± 0.02 and 0.09 ± 0.02 mag, respectively. A linear model finds significant slopes of –0.021 ± 0.006 and –0.030 ± 0.009 mag (10 3 km s –1 ) –1 for intrinsic B – V and B – R colors versus velocity, respectively. Because the ejecta velocity distribution is skewed toward high velocities, these effects imply non-Gaussian intrinsic color distributions with skewness up to +0.3. Accounting for the intrinsic-color-velocity correlation results in corrections to A V extinction estimates as large as –0.12 mag for HV SNe Ia and +0.06 mag for NV events. Velocity measurements from SN Ia spectra have the potential to diminish systematic errors from the confounding of intrinsic colors and dust reddening affecting supernova distances
Cosmological Non-Gaussian Signature Detection: Comparing Performance of Different Statistical Tests
Directory of Open Access Journals (Sweden)
O. Forni
2005-09-01
Full Text Available Currently, it appears that the best method for non-Gaussianity detection in the cosmic microwave background (CMB consists in calculating the kurtosis of the wavelet coefficients. We know that wavelet-kurtosis outperforms other methods such as the bispectrum, the genus, ridgelet-kurtosis, and curvelet-kurtosis on an empirical basis, but relatively few studies have compared other transform-based statistics, such as extreme values, or more recent tools such as higher criticism (HC, or proposed Ã¢Â€Âœbest possibleÃ¢Â€Â choices for such statistics. In this paper, we consider two models for transform-domain coefficients: (a a power-law model, which seems suited to the wavelet coefficients of simulated cosmic strings, and (b a sparse mixture model, which seems suitable for the curvelet coefficients of filamentary structure. For model (a, if power-law behavior holds with finite 8th moment, excess kurtosis is an asymptotically optimal detector, but if the 8th moment is not finite, a test based on extreme values is asymptotically optimal. For model (b, if the transform coefficients are very sparse, a recent test, higher criticism, is an optimal detector, but if they are dense, kurtosis is an optimal detector. Empirical wavelet coefficients of simulated cosmic strings have power-law character, infinite 8th moment, while curvelet coefficients of the simulated cosmic strings are not very sparse. In all cases, excess kurtosis seems to be an effective test in moderate-resolution imagery.
Lefèvre, Victor; Lopez-Pamies, Oscar
2017-02-01
This paper presents an analytical framework to construct approximate homogenization solutions for the macroscopic elastic dielectric response - under finite deformations and finite electric fields - of dielectric elastomer composites with two-phase isotropic particulate microstructures. The central idea consists in employing the homogenization solution derived in Part I of this work for ideal elastic dielectric composites within the context of a nonlinear comparison medium method - this is derived as an extension of the comparison medium method of Lopez-Pamies et al. (2013) in nonlinear elastostatics to the coupled realm of nonlinear electroelastostatics - to generate in turn a corresponding solution for composite materials with non-ideal elastic dielectric constituents. Complementary to this analytical framework, a hybrid finite-element formulation to construct homogenization solutions numerically (in three dimensions) is also presented. The proposed analytical framework is utilized to work out a general approximate homogenization solution for non-Gaussian dielectric elastomers filled with nonlinear elastic dielectric particles that may exhibit polarization saturation. The solution applies to arbitrary (non-percolative) isotropic distributions of filler particles. By construction, it is exact in the limit of small deformations and moderate electric fields. For finite deformations and finite electric fields, its accuracy is demonstrated by means of direct comparisons with finite-element solutions. Aimed at gaining physical insight into the extreme enhancement in electrostriction properties displayed by emerging dielectric elastomer composites, various cases wherein the filler particles are of poly- and mono-disperse sizes and exhibit different types of elastic dielectric behavior are discussed in detail. Contrary to an initial conjecture in the literature, it is found (inter alia) that the isotropic addition of a small volume fraction of stiff (semi
Discriminative learning of receptive fields from responses to non-Gaussian stimulus ensembles.
Meyer, Arne F; Diepenbrock, Jan-Philipp; Happel, Max F K; Ohl, Frank W; Anemüller, Jörn
2014-01-01
Analysis of sensory neurons' processing characteristics requires simultaneous measurement of presented stimuli and concurrent spike responses. The functional transformation from high-dimensional stimulus space to the binary space of spike and non-spike responses is commonly described with linear-nonlinear models, whose linear filter component describes the neuron's receptive field. From a machine learning perspective, this corresponds to the binary classification problem of discriminating spike-eliciting from non-spike-eliciting stimulus examples. The classification-based receptive field (CbRF) estimation method proposed here adapts a linear large-margin classifier to optimally predict experimental stimulus-response data and subsequently interprets learned classifier weights as the neuron's receptive field filter. Computational learning theory provides a theoretical framework for learning from data and guarantees optimality in the sense that the risk of erroneously assigning a spike-eliciting stimulus example to the non-spike class (and vice versa) is minimized. Efficacy of the CbRF method is validated with simulations and for auditory spectro-temporal receptive field (STRF) estimation from experimental recordings in the auditory midbrain of Mongolian gerbils. Acoustic stimulation is performed with frequency-modulated tone complexes that mimic properties of natural stimuli, specifically non-Gaussian amplitude distribution and higher-order correlations. Results demonstrate that the proposed approach successfully identifies correct underlying STRFs, even in cases where second-order methods based on the spike-triggered average (STA) do not. Applied to small data samples, the method is shown to converge on smaller amounts of experimental recordings and with lower estimation variance than the generalized linear model and recent information theoretic methods. Thus, CbRF estimation may prove useful for investigation of neuronal processes in response to natural stimuli and
Discriminative learning of receptive fields from responses to non-Gaussian stimulus ensembles.
Directory of Open Access Journals (Sweden)
Arne F Meyer
Full Text Available Analysis of sensory neurons' processing characteristics requires simultaneous measurement of presented stimuli and concurrent spike responses. The functional transformation from high-dimensional stimulus space to the binary space of spike and non-spike responses is commonly described with linear-nonlinear models, whose linear filter component describes the neuron's receptive field. From a machine learning perspective, this corresponds to the binary classification problem of discriminating spike-eliciting from non-spike-eliciting stimulus examples. The classification-based receptive field (CbRF estimation method proposed here adapts a linear large-margin classifier to optimally predict experimental stimulus-response data and subsequently interprets learned classifier weights as the neuron's receptive field filter. Computational learning theory provides a theoretical framework for learning from data and guarantees optimality in the sense that the risk of erroneously assigning a spike-eliciting stimulus example to the non-spike class (and vice versa is minimized. Efficacy of the CbRF method is validated with simulations and for auditory spectro-temporal receptive field (STRF estimation from experimental recordings in the auditory midbrain of Mongolian gerbils. Acoustic stimulation is performed with frequency-modulated tone complexes that mimic properties of natural stimuli, specifically non-Gaussian amplitude distribution and higher-order correlations. Results demonstrate that the proposed approach successfully identifies correct underlying STRFs, even in cases where second-order methods based on the spike-triggered average (STA do not. Applied to small data samples, the method is shown to converge on smaller amounts of experimental recordings and with lower estimation variance than the generalized linear model and recent information theoretic methods. Thus, CbRF estimation may prove useful for investigation of neuronal processes in response to
Bose, S
2002-01-01
The robust statistic proposed by Creighton (Creighton J D E 1999 Phys. Rev. D 60 021101) and Allen et al (Allen et al 2001 Preprint gr-gc/010500) for the detection of stationary non-Gaussian noise is briefly reviewed. We compute the robust statistic for generic weak gravitational-wave signals in the mixture-Gaussian noise model to an accuracy higher than in those analyses, and reinterpret its role. Specifically, we obtain the coherent statistic for detecting gravitational-wave signals from inspiralling compact binaries with an arbitrary network of earth-based interferometers. Finally, we show that excess computational costs incurred owing to non-Gaussianity is negligible compared to the cost of detection in Gaussian noise.
Energy Technology Data Exchange (ETDEWEB)
Chrzanowski, H. M.; Bernu, J.; Sparkes, B. M.; Hage, B.; Lam, P. K.; Symul, T. [Centre for Quantum Computation and Communication Technology, Quantum Optics group, Department of Quantum Science, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia); Lund, A. P. [Centre for Quantum Computation and Communication Technology, Centre for Quantum Dynamics, Griffith University, Nathan QLD 4111 (Australia); Ralph, T. C. [Centre for Quantum Computation and Communication Technology, Department of Physics, University of Queensland, St. Lucia QLD 4072 (Australia)
2011-11-15
The nonlinearity of a conditional photon-counting measurement can be used to ''de-Gaussify'' a Gaussian state of light. Here we present and experimentally demonstrate a technique for photon-number resolution using only homodyne detection. We then apply this technique to inform a conditional measurement, unambiguously reconstructing the statistics of the non-Gaussian one- and two-photon-subtracted squeezed vacuum states. Although our photon-number measurement relies on ensemble averages and cannot be used to prepare non-Gaussian states of light, its high efficiency, photon-number-resolving capabilities, and compatibility with the telecommunications band make it suitable for quantum-information tasks relying on the outcomes of mean values.
Energy Technology Data Exchange (ETDEWEB)
Zentner, I. [IMSIA, UMR EDF-ENSTA-CNRS-CEA 9219, Université Paris-Saclay, 828 Boulevard des Maréchaux, 91762 Palaiseau Cedex (France); Ferré, G., E-mail: gregoire.ferre@ponts.org [CERMICS – Ecole des Ponts ParisTech, 6 et 8 avenue Blaise Pascal, Cité Descartes, Champs sur Marne, 77455 Marne la Vallée Cedex 2 (France); Poirion, F. [Department of Structural Dynamics and Aeroelasticity, ONERA, BP 72, 29 avenue de la Division Leclerc, 92322 Chatillon Cedex (France); Benoit, M. [Institut de Recherche sur les Phénomènes Hors Equilibre (IRPHE), UMR 7342 (CNRS, Aix-Marseille Université, Ecole Centrale Marseille), 49 rue Frédéric Joliot-Curie, BP 146, 13384 Marseille Cedex 13 (France)
2016-06-01
In this paper, a new method for the identification and simulation of non-Gaussian and non-stationary stochastic fields given a database is proposed. It is based on two successive biorthogonal decompositions aiming at representing spatio–temporal stochastic fields. The proposed double expansion allows to build the model even in the case of large-size problems by separating the time, space and random parts of the field. A Gaussian kernel estimator is used to simulate the high dimensional set of random variables appearing in the decomposition. The capability of the method to reproduce the non-stationary and non-Gaussian features of random phenomena is illustrated by applications to earthquakes (seismic ground motion) and sea states (wave heights).
Camera, Stefano; Santos, Mário G; Ferreira, Pedro G; Ferramacho, Luís
2013-10-25
The large-scale structure of the Universe supplies crucial information about the physical processes at play at early times. Unresolved maps of the intensity of 21 cm emission from neutral hydrogen HI at redshifts z=/~1-5 are the best hope of accessing the ultralarge-scale information, directly related to the early Universe. A purpose-built HI intensity experiment may be used to detect the large scale effects of primordial non-Gaussianity, placing stringent bounds on different models of inflation. We argue that it may be possible to place tight constraints on the non-Gaussianity parameter f(NL), with an error close to σ(f(NL))~1.
Energy Technology Data Exchange (ETDEWEB)
Miao, Yan-Gang [Nankai University, School of Physics, Tianjin (China); Chinese Academy of Sciences, State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, P.O. Box 2735, Beijing (China); CERN, PH-TH Division, Geneva 23 (Switzerland); Xu, Zhen-Ming [Nankai University, School of Physics, Tianjin (China)
2016-04-15
Considering non-Gaussian smeared matter distributions, we investigate the thermodynamic behaviors of the noncommutative high-dimensional Schwarzschild-Tangherlini anti-de Sitter black hole, and we obtain the condition for the existence of extreme black holes. We indicate that the Gaussian smeared matter distribution, which is a special case of non-Gaussian smeared matter distributions, is not applicable for the six- and higher-dimensional black holes due to the hoop conjecture. In particular, the phase transition is analyzed in detail. Moreover, we point out that the Maxwell equal area law holds for the noncommutative black hole whose Hawking temperature is within a specific range, but fails for one whose the Hawking temperature is beyond this range. (orig.)
Phase coherence among the Fourier modes and non-Gaussian characteristics in the Alfvén chaos system
Nariyuki, Yasuhiro; Sasaki, Makoto; Kasuya, Naohiro; Hada, Tohru; Yagi, Masatoshi
2017-03-01
Non-Gaussian characteristics in time series of the Alfvén chaos system are discussed. The phase coherence index, a measure defined by using the surrogate data method and the structure function, is used to evaluate the phase coherence among the Fourier modes. Through Monte Carlo significance testing, it is found that the phase coherence decays monotonically with increasing dissipative parameter and time scale. By applying the Mori projection operator method assuming the Markov process, a model equation for the time correlation function is derived from the generalized Langevin equation. As opposed to the result of the phase coherence analysis, it is concluded that the difference between the direct numerical simulation and the model equation becomes pronounced as the dissipative parameters are increased. This suggests that, even when the phase coherence index is not significant, the underlying physical system may be a non-Gaussian process.
Miao, Yan-Gang
2016-01-01
Considering non-Gaussian smeared matter distributions, we investigate thermodynamic behaviors of the noncommutative high-dimensional Schwarzschild-Tangherlini anti-de Sitter black hole, and obtain the condition for the existence of extreme black holes. We indicate that the Gaussian smeared matter distribution, which is a special case of non-Gaussian smeared matter distributions, is not applicable for the 6- and higher-dimensional black holes due to the hoop conjecture. In particular, the phase transition is analyzed in detail. Moreover, we point out that the Maxwell equal area law maintains for the noncommutative black hole with the Hawking temperature within a specific range, but fails with the Hawking temperature beyond this range.
Monfared, Yashar E.; Ponomarenko, Sergey A.
2017-10-01
We explore theoretically and numerically extreme event excitation in stimulated Raman scattering in gases. We consider gas-filled hollow-core photonic crystal fibers as a particular system realization. We show that moderate amplitude pump fluctuations obeying Gaussian statistics lead to the emergence of heavy-tailed non-Gaussian statistics as coherent seed Stokes pulses are amplified on propagation along the fiber. We reveal the crucial role that coherent memory effects play in causing non-Gaussian statistics of the system. We discover that extreme events can occur even at the initial stage of stimulated Raman scattering when one can neglect energy depletion of an intense, strongly fluctuating Gaussian pump source. Our analytical results in the undepleted pump approximation explicitly illustrate power-law probability density generation as the input pump noise is transferred to the output Stokes pulses.
Tyagi, Neha; Cherayil, Binny J.
2018-03-01
The increasingly widespread occurrence in complex fluids of particle motion that is both Brownian and non-Gaussian has recently been found to be successfully modeled by a process (frequently referred to as ‘diffusing diffusivity’) in which the white noise that governs Brownian diffusion is itself stochastically modulated by either Ornstein–Uhlenbeck dynamics or by two-state noise. But the model has so far not been able to account for an aspect of non-Gaussian Brownian motion that is also commonly observed: a non-monotonic decay of the parameter that quantifies the extent of deviation from Gaussian behavior. In this paper, we show that the inclusion of memory effects in the model—via a generalized Langevin equation—can rationalise this phenomenon.
International Nuclear Information System (INIS)
Chrzanowski, H. M.; Bernu, J.; Sparkes, B. M.; Hage, B.; Lam, P. K.; Symul, T.; Lund, A. P.; Ralph, T. C.
2011-01-01
The nonlinearity of a conditional photon-counting measurement can be used to ''de-Gaussify'' a Gaussian state of light. Here we present and experimentally demonstrate a technique for photon-number resolution using only homodyne detection. We then apply this technique to inform a conditional measurement, unambiguously reconstructing the statistics of the non-Gaussian one- and two-photon-subtracted squeezed vacuum states. Although our photon-number measurement relies on ensemble averages and cannot be used to prepare non-Gaussian states of light, its high efficiency, photon-number-resolving capabilities, and compatibility with the telecommunications band make it suitable for quantum-information tasks relying on the outcomes of mean values.
Fast fitting of non-Gaussian state-space models to animal movement data via Template Model Builder
DEFF Research Database (Denmark)
Albertsen, Christoffer Moesgaard; Whoriskey, Kim; Yurkowski, David
2015-01-01
recommend using the Laplace approximation combined with automatic differentiation (as implemented in the novel R package Template Model Builder; TMB) for the fast fitting of continuous-time multivariate non-Gaussian SSMs. Through Argos satellite tracking data, we demonstrate that the use of continuous...... are able to estimate additional parameters compared to previous methods, all without requiring a substantial increase in computational time. The model implementation is made available through the R package argosTrack....
Wilson loop's phase transition probed by non-local observable
Directory of Open Access Journals (Sweden)
Hui-Ling Li
2018-04-01
Full Text Available In order to give further insights into the holographic Van der Waals phase transition, it would be of great interest to investigate the behavior of Wilson loop across the holographic phase transition for a higher dimensional hairy black hole. We offer a possibility to proceed with a numerical calculation in order to discussion on the hairy black hole's phase transition, and show that Wilson loop can serve as a probe to detect a phase structure of the black hole. Furthermore, for a first order phase transition, we calculate numerically the Maxwell's equal area construction; and for a second order phase transition, we also study the critical exponent in order to characterize the Wilson loop's phase transition.
Directory of Open Access Journals (Sweden)
Ronghui ZHENG
2017-12-01
Full Text Available A control method for Multi-Input Multi-Output (MIMO non-Gaussian random vibration test with cross spectra consideration is proposed in the paper. The aim of the proposed control method is to replicate the specified references composed of auto spectral densities, cross spectral densities and kurtoses on the test article in the laboratory. It is found that the cross spectral densities will bring intractable coupling problems and induce difficulty for the control of the multi-output kurtoses. Hence, a sequential phase modification method is put forward to solve the coupling problems in multi-input multi-output non-Gaussian random vibration test. To achieve the specified responses, an improved zero memory nonlinear transformation is utilized first to modify the Fourier phases of the signals with sequential phase modification method to obtain one frame reference response signals which satisfy the reference spectra and reference kurtoses. Then, an inverse system method is used in frequency domain to obtain the continuous stationary drive signals. At the same time, the matrix power control algorithm is utilized to control the spectra and kurtoses of the response signals further. At the end of the paper, a simulation example with a cantilever beam and a vibration shaker test are implemented and the results support the proposed method very well. Keywords: Cross spectra, Kurtosis control, Multi-input multi-output, Non-Gaussian, Random vibration test
Is cosmic acceleration proven by local cosmological probes?
Tutusaus, I.; Lamine, B.; Dupays, A.; Blanchard, A.
2017-06-01
Context. The cosmological concordance model (ΛCDM) matches the cosmological observations exceedingly well. This model has become the standard cosmological model with the evidence for an accelerated expansion provided by the type Ia supernovae (SNIa) Hubble diagram. However, the robustness of this evidence has been addressed recently with somewhat diverging conclusions. Aims: The purpose of this paper is to assess the robustness of the conclusion that the Universe is indeed accelerating if we rely only on low-redshift (z ≲ 2) observations, that is to say with SNIa, baryonic acoustic oscillations, measurements of the Hubble parameter at different redshifts, and measurements of the growth of matter perturbations. Methods: We used the standard statistical procedure of minimizing the χ2 function for the different probes to quantify the goodness of fit of a model for both ΛCDM and a simple nonaccelerated low-redshift power law model. In this analysis, we do not assume that supernovae intrinsic luminosity is independent of the redshift, which has been a fundamental assumption in most previous studies that cannot be tested. Results: We have found that, when SNIa intrinsic luminosity is not assumed to be redshift independent, a nonaccelerated low-redshift power law model is able to fit the low-redshift background data as well as, or even slightly better, than ΛCDM. When measurements of the growth of structures are added, a nonaccelerated low-redshift power law model still provides an excellent fit to the data for all the luminosity evolution models considered. Conclusions: Without the standard assumption that supernovae intrinsic luminosity is independent of the redshift, low-redshift probes are consistent with a nonaccelerated universe.
Soury, Hamza
2016-06-29
The Gaussian distribution is typically used to model the additive noise affecting communication systems. However, in many cases the noise cannot be modeled by a Gaussian distribution. In this thesis, we investigate the performance of different communication systems perturbed by non-Gaussian noise. Three families of noise are considered in this work, namely the generalized Gaussian noise, the Laplace noise/interference, and the impulsive noise that is modeled by an α-stable distribution. More specifically, in the first part of this thesis, the impact of an additive generalized Gaussian noise is studied by computing the average symbol error rate (SER) of one dimensional and two dimensional constellations in fading environment. We begin by the simple case of two symbols, i.e. binary phase shift keying (BPSK) constellation. From the results of this constellation, we extended the work to the average SER of an M pulse amplitude modulation (PAM). The first 2 − D constellation is the M quadrature amplitude modulation (QAM) (studied for two geometric shapes, namely square and rectangular), which is the combination of two orthogonal PAM signals (in-phase and quadrature phase PAM). In the second part, the system performance of a circular constellation, namely M phase shift keying (MPSK) is studied in conjunction with a Laplace noise with independent noise components. A closed form and an asymptotic expansion of the SER are derived for two detectors, maximum likelihood and minimum distance detectors. Next, we look at the intra cell interference of a full duplex cellular network which is shown to follow a Laplacian distribution with dependent, but uncorrelated, complex components. The densities of that interference are expressed in a closed form in order to obtain the SER of several communication systems (BPSK, PAM, QAM, and MPSK). Finally, we study the statistics of the α-stable distribution. Those statistics are expressed in closed form in terms of the Fox H function and
Probing many-body localization with neural networks
Schindler, Frank; Regnault, Nicolas; Neupert, Titus
2017-06-01
We show that a simple artificial neural network trained on entanglement spectra of individual states of a many-body quantum system can be used to determine the transition between a many-body localized and a thermalizing regime. Specifically, we study the Heisenberg spin-1/2 chain in a random external field. We employ a multilayer perceptron with a single hidden layer, which is trained on labeled entanglement spectra pertaining to the fully localized and fully thermal regimes. We then apply this network to classify spectra belonging to states in the transition region. For training, we use a cost function that contains, in addition to the usual error and regularization parts, a term that favors a confident classification of the transition region states. The resulting phase diagram is in good agreement with the one obtained by more conventional methods and can be computed for small systems. In particular, the neural network outperforms conventional methods in classifying individual eigenstates pertaining to a single disorder realization. It allows us to map out the structure of these eigenstates across the transition with spatial resolution. Furthermore, we analyze the network operation using the dreaming technique to show that the neural network correctly learns by itself the power-law structure of the entanglement spectra in the many-body localized regime.
Two-dimensional atom localization via probe absorption in a four-level atomic system
International Nuclear Information System (INIS)
Wang Zhi-Ping; Ge Qiang; Ruan Yu-Hua; Yu Ben-Li
2013-01-01
We have investigated the two-dimensional (2D) atom localization via probe absorption in a coherently driven four-level atomic system by means of a radio-frequency field driving a hyperfine transition. It is found that the detecting probability and precision of 2D atom localization can be significantly improved via adjusting the system parameters. As a result, our scheme may be helpful in laser cooling or the atom nano-lithography via atom localization
Optical Polarization as a Probe of the Local Interstellar Medium
Tinbergen, J.
1984-01-01
The use of interstellar polarization as a tool for measuring interstellar dust is discussed. Problems resulting from dust and magnetic field configurations becoming mixed up are discussed, as is the availability of sufficiently bright stars to obtain the photons needed for precision measurements. It is proposed that: (1) on the scale of several hundred parsec, there is a preferential magnetic field direction, as evidenced by observations at the Galactic poles and selected longitudes in the Galactic plane; (2) the local (r 50 pc) region is devoid of dust, as evidenced by the mean square degree of polarization as a function of distance; and, less certainly, that (3) at a distance of less than 5 pc, there is a patch of dust which may be of interest in connection with cloud models.
International Nuclear Information System (INIS)
Fan Hong-Yi; Wang Zhen
2014-01-01
For directly normalizing the photon non-Gaussian states (e.g., photon added and subtracted squeezed states), we use the method of integration within an ordered product (IWOP) of operators to derive some new bosonic operator-ordering identities. We also derive some new integration transformation formulas about one- and two-variable Hermite polynomials in complex function space. These operator identities and associative integration formulas provide much convenience for constructing non-Gaussian states in quantum engineering. (general)
Localized excitations in superconducting point contacts: probing the Andreev doublet
International Nuclear Information System (INIS)
Bretheau, L.
2013-01-01
The Josephson effect describes the coherent coupling between superconductors and the resulting supercurrent. Microscopically, it arises from the existence of discrete quasiparticle states, localized at the weak link, the Andreev bound states. They come in doublets in each conduction channel of the weak link, with energies symmetric about the Fermi energy and opposite supercurrents. Each Andreev doublet gives rise to four states: the ground state |-> and the excited state |+>, with even parity, and the excited odd states |↑> and |↓>. Is it possible to address and control Andreev doublets? This thesis describes two sets of experiments designed to answer this question using the most basic Josephson element, a one-atom contact between two superconducting electrodes. In a first experiment, we have observed and characterized the excited odd states |↑> and |↓>. As expected for a spin-degenerate system, they do not carry supercurrent. In this experiment the excitation was uncontrolled and resulted from trapping of spurious quasiparticles. We have measured the lifetime of the odd states: under some condition, it is found to exceed 100 μs. The second experiment is a photon-absorption spectroscopy of the Andreev doublet. It was performed by using a Josephson junction as an integrated on-chip microwave emitter and detector. The observed Andreev transitions correspond to excitation from the ground state |->to the excited even state |+>, and are well accounted for by our quantum model. This result opens the way to coherent manipulation of this two level system. The direct observation of the excited Andreev state, either by quasiparticle-injection or photon-absorption, strongly supports the mesoscopic theory of the Josephson effect. It shows that in addition to the phase difference, each channel of a Josephson weak link possesses an internal fermionic degree of freedom. It could be used to code information in a novel type of superconducting qubit. (author) [fr
Libera, Arianna; de Barros, Felipe P. J.; Riva, Monica; Guadagnini, Alberto
2017-10-01
Our study is keyed to the analysis of the interplay between engineering factors (i.e., transient pumping rates versus less realistic but commonly analyzed uniform extraction rates) and the heterogeneous structure of the aquifer (as expressed by the probability distribution characterizing transmissivity) on contaminant transport. We explore the joint influence of diverse (a) groundwater pumping schedules (constant and variable in time) and (b) representations of the stochastic heterogeneous transmissivity (T) field on temporal histories of solute concentrations observed at an extraction well. The stochastic nature of T is rendered by modeling its natural logarithm, Y = ln T, through a typical Gaussian representation and the recently introduced Generalized sub-Gaussian (GSG) model. The latter has the unique property to embed scale-dependent non-Gaussian features of the main statistics of Y and its (spatial) increments, which have been documented in a variety of studies. We rely on numerical Monte Carlo simulations and compute the temporal evolution at the well of low order moments of the solute concentration (C), as well as statistics of the peak concentration (Cp), identified as the environmental performance metric of interest in this study. We show that the pumping schedule strongly affects the pattern of the temporal evolution of the first two statistical moments of C, regardless the nature (Gaussian or non-Gaussian) of the underlying Y field, whereas the latter quantitatively influences their magnitude. Our results show that uncertainty associated with C and Cp estimates is larger when operating under a transient extraction scheme than under the action of a uniform withdrawal schedule. The probability density function (PDF) of Cp displays a long positive tail in the presence of time-varying pumping schedule. All these aspects are magnified in the presence of non-Gaussian Y fields. Additionally, the PDF of Cp displays a bimodal shape for all types of pumping
Directory of Open Access Journals (Sweden)
Xinying Xu
2018-06-01
Full Text Available In this paper, a novel data-driven single neuron predictive control strategy is proposed for non-Gaussian networked control systems with metrology delays in the information theory framework. Firstly, survival information potential (SIP, instead of minimum entropy, is used to formulate the performance index to characterize the randomness of the considered systems, which is calculated by oversampling method. Then the minimum values can be computed by optimizing the SIP-based performance index. Finally, the proposed strategy, minimum entropy method and mean square error (MSE are applied to a networked motor control system, and results demonstrated the effectiveness of the proposed strategy.
International Nuclear Information System (INIS)
Woulache, R.L.; Kofane, T.C.; Yemele, D.
2005-08-01
Thermal nucleation of kink-antikink pairs in a nonlinear Klein- Gordon model with Remoissenet-Peyrard substrate potential coupled to an applied field is analyzed in the limits of moderate temperature and strong damping. We derive analytically the non- Gaussian correction to the nucleation rate formula of kink- antikink pairs previously calculated by Yemele and Kofane and show that the correction factor depends on the intensity of the applied field, the temperature of the system and the shape of the substrate potential. (author)
DEFF Research Database (Denmark)
Li, Chunjian; Andersen, Søren Vang
2007-01-01
We propose two blind system identification methods that exploit the underlying dynamics of non-Gaussian signals. The two signal models to be identified are: an Auto-Regressive (AR) model driven by a discrete-state Hidden Markov process, and the same model whose output is perturbed by white Gaussi...... outputs. The signal models are general and suitable to numerous important signals, such as speech signals and base-band communication signals. Applications to speech analysis and blind channel equalization are given to exemplify the efficiency of the new methods....
Directory of Open Access Journals (Sweden)
Pan Zhao
2018-01-01
Full Text Available In this paper we consider pricing problems of the geometric average Asian options under a non-Gaussian model, in which the underlying stock price is driven by a process based on non-extensive statistical mechanics. The model can describe the peak and fat tail characteristics of returns. Thus, the description of underlying asset price and the pricing of options are more accurate. Moreover, using the martingale method, we obtain closed form solutions for geometric average Asian options. Furthermore, the numerical analysis shows that the model can avoid underestimating risks relative to the Black-Scholes model.
Energy Technology Data Exchange (ETDEWEB)
Liu, Yunlong; Wang, Aiping; Guo, Lei; Wang, Hong
2017-07-09
This paper presents an error-entropy minimization tracking control algorithm for a class of dynamic stochastic system. The system is represented by a set of time-varying discrete nonlinear equations with non-Gaussian stochastic input, where the statistical properties of stochastic input are unknown. By using Parzen windowing with Gaussian kernel to estimate the probability densities of errors, recursive algorithms are then proposed to design the controller such that the tracking error can be minimized. The performance of the error-entropy minimization criterion is compared with the mean-square-error minimization in the simulation results.
Near-field optical microscopy of localized excitations on rough surfaces: influence of a probe
DEFF Research Database (Denmark)
Bozhevolnyi, Sergey I.
1999-01-01
Starting from the general principles of near-field optical microscopy. I consider the influence of a probe when being used to image localized dipolar excitations and suggest a way of evaluating the perturbation thus introduced. Using the rigorous microscopic (electric) point-dipole description, I...
Chang, Anteng; Li, Huajun; Wang, Shuqing; Du, Junfeng
2017-08-01
Both wave-frequency (WF) and low-frequency (LF) components of mooring tension are in principle non-Gaussian due to nonlinearities in the dynamic system. This paper conducts a comprehensive investigation of applicable probability density functions (PDFs) of mooring tension amplitudes used to assess mooring-line fatigue damage via the spectral method. Short-term statistical characteristics of mooring-line tension responses are firstly investigated, in which the discrepancy arising from Gaussian approximation is revealed by comparing kurtosis and skewness coefficients. Several distribution functions based on present analytical spectral methods are selected to express the statistical distribution of the mooring-line tension amplitudes. Results indicate that the Gamma-type distribution and a linear combination of Dirlik and Tovo-Benasciutti formulas are suitable for separate WF and LF mooring tension components. A novel parametric method based on nonlinear transformations and stochastic optimization is then proposed to increase the effectiveness of mooring-line fatigue assessment due to non-Gaussian bimodal tension responses. Using time domain simulation as a benchmark, its accuracy is further validated using a numerical case study of a moored semi-submersible platform.
Li, Tiejun; Min, Bin; Wang, Zhiming
2013-03-14
The stochastic integral ensuring the Newton-Leibnitz chain rule is essential in stochastic energetics. Marcus canonical integral has this property and can be understood as the Wong-Zakai type smoothing limit when the driving process is non-Gaussian. However, this important concept seems not well-known for physicists. In this paper, we discuss Marcus integral for non-Gaussian processes and its computation in the context of stochastic energetics. We give a comprehensive introduction to Marcus integral and compare three equivalent definitions in the literature. We introduce the exact pathwise simulation algorithm and give the error analysis. We show how to compute the thermodynamic quantities based on the pathwise simulation algorithm. We highlight the information hidden in the Marcus mapping, which plays the key role in determining thermodynamic quantities. We further propose the tau-leaping algorithm, which advance the process with deterministic time steps when tau-leaping condition is satisfied. The numerical experiments and its efficiency analysis show that it is very promising.
Directory of Open Access Journals (Sweden)
Jinliang Xu
2013-06-01
Full Text Available This paper investigates the filtering problem for multivariate continuous nonlinear non-Gaussian systems based on an improved minimum error entropy (MEE criterion. The system is described by a set of nonlinear continuous equations with non-Gaussian system noises and measurement noises. The recently developed generalized density evolution equation is utilized to formulate the joint probability density function (PDF of the estimation errors. Combining the entropy of the estimation error with the mean squared error, a novel performance index is constructed to ensure the estimation error not only has small uncertainty but also approaches to zero. According to the conjugate gradient method, the optimal filter gain matrix is then obtained by minimizing the improved minimum error entropy criterion. In addition, the condition is proposed to guarantee that the estimation error dynamics is exponentially bounded in the mean square sense. Finally, the comparative simulation results are presented to show that the proposed MEE filter is superior to nonlinear unscented Kalman filter (UKF.
Fekete, Z.; Csernai, M.; Kocsis, K.; Horváth, Á. C.; Pongrácz, A.; Barthó, P.
2017-06-01
Objective. Temperature is an important factor for neural function both in normal and pathological states, nevertheless, simultaneous monitoring of local brain temperature and neuronal activity has not yet been undertaken. Approach. In our work, we propose an implantable, calibrated multimodal biosensor that facilitates the complex investigation of thermal changes in both cortical and deep brain regions, which records multiunit activity of neuronal populations in mice. The fabricated neural probe contains four electrical recording sites and a platinum temperature sensor filament integrated on the same probe shaft within a distance of 30 µm from the closest recording site. The feasibility of the simultaneous functionality is presented in in vivo studies. The probe was tested in the thalamus of anesthetized mice while manipulating the core temperature of the animals. Main results. We obtained multiunit and local field recordings along with measurement of local brain temperature with accuracy of 0.14 °C. Brain temperature generally followed core body temperature, but also showed superimposed fluctuations corresponding to epochs of increased local neural activity. With the application of higher currents, we increased the local temperature by several degrees without observable tissue damage between 34-39 °C. Significance. The proposed multifunctional tool is envisioned to broaden our knowledge on the role of the thermal modulation of neuronal activity in both cortical and deeper brain regions.
Mobile Device Passive Localization Based on IEEE 802.11 Probe Request Frames
Directory of Open Access Journals (Sweden)
Lin Sun
2017-01-01
Full Text Available This paper presents a novel passive mobile device localization mode based on IEEE 802.11 Probe Request frames. In this approach, the listener can discover mobile devices by receiving the Probe Request frames and localize them on his walking path. The unique location of the mobile device is estimated on a geometric diagram and right-angled walking path. In model equations, site-related parameter, that is, path loss exponent, is eliminated to make the approach site-independent. To implement unique localization, the right-angled walking path is designed and the optimal location is estimated from the optional points. The performance of our method has been evaluated inside the room, outside the room, and in outdoor scenarios. Three kinds of walking paths, for example, horizontal, vertical, and slanted, are also tested.
Energy Technology Data Exchange (ETDEWEB)
Umeh, Obinna; Jolicoeur, Sheean; Maartens, Roy [Department of Physics and Astronomy, University of the Western Cape, Robert Sobukwe Road, Cape Town 7535 (South Africa); Clarkson, Chris, E-mail: umeobinna@gmail.com, E-mail: beautifulheart369@gmail.com, E-mail: roy.maartens@gmail.com, E-mail: chris.clarkson@gmail.com [School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom)
2017-03-01
Next-generation galaxy surveys will increasingly rely on the galaxy bispectrum to improve cosmological constraints, especially on primordial non-Gaussianity. A key theoretical requirement that remains to be developed is the analysis of general relativistic effects on the bispectrum, which arise from observing galaxies on the past lightcone, as well as from relativistic corrections to the dynamics. As an initial step towards a fully relativistic analysis of the galaxy bispectrum, we compute for the first time the local relativistic lightcone effects on the bispectrum, which come from Doppler and gravitational potential contributions. For the galaxy bispectrum, the problem is much more complex than for the power spectrum, since we need the lightcone corrections at second order. Mode-coupling contributions at second order mean that relativistic corrections can be non-negligible at smaller scales than in the case of the power spectrum. In a primordial Gaussian universe, we show that the local lightcone projection effects for squeezed shapes at z ∼ 1 mean that the bispectrum can differ from the Newtonian prediction by ∼> 10% when the short modes are k ∼< (50 Mpc){sup −1}. These relativistic projection effects, if ignored in the analysis of observations, could be mistaken for primordial non-Gaussianity. For upcoming surveys which probe equality scales and beyond, all relativistic lightcone effects and relativistic dynamical corrections should be included for an accurate measurement of primordial non-Gaussianity.
Directory of Open Access Journals (Sweden)
Miao Wan
2010-07-01
Full Text Available An nm-thickness composite gold thin film consisting of gold nanoparticles and polyelectrolytes is fabricated through ionic self-assembled multilayers (ISAM technique and is deposited on end-faces of optical fibers to construct localized surface plasmon resonance (LSPR fiber probes. We demonstrate that the LSPR spectrum induced by ISAM gold films can be fine-tuned through the ISAM procedure. We investigate variations of reflection spectra of the probe with respect to the layer-by-layer adsorption of ISAMs onto end-faces of fibers, and study the spectral variation mechanism. Finally, we demonstrated using this fiber probe to detect the biotin-streptavidin bioconjugate pair. ISAM adsorbed on optical fibers potentially provides a simple, fast, robust, and low-cost, platform for LSPR biosensing applications.
Scanning thermo-ionic microscopy for probing local electrochemistry at the nanoscale
Energy Technology Data Exchange (ETDEWEB)
Eshghinejad, Ahmadreza; Nasr Esfahani, Ehsan; Wang, Peiqi; Li, Jiangyu, E-mail: jjli@uw.edu [Department of Mechanical Engineering, University of Washington, Seattle, Washington 98195 (United States); Xie, Shuhong [Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, Hunan (China); Shenzhen Key Laboratory of Nanobiomechanics, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, Guangdong (China); Geary, Timothy C.; Adler, Stuart B. [Department of Chemical Engineering, University of Washington, Seattle, Washington 98195 (United States)
2016-05-28
Conventional electrochemical characterization techniques based on voltage and current measurements only probe faradaic and capacitive rates in aggregate. In this work we develop a scanning thermo-ionic microscopy (STIM) to probe local electrochemistry at the nanoscale, based on imaging of Vegard strain induced by thermal oscillation. It is demonstrated from both theoretical analysis and experimental validation that the second harmonic response of thermally induced cantilever vibration, associated with thermal expansion, is present in all solids, whereas the fourth harmonic response, caused by local transport of mobile species, is only present in ionic materials. The origin of STIM response is further confirmed by its reduced amplitude with respect to increased contact force, due to the coupling of stress to concentration of ionic species and/or electronic defects. The technique has been applied to probe Sm-doped Ceria and LiFePO{sub 4}, both of which exhibit higher concentrations of mobile species near grain boundaries. The STIM gives us a powerful method to study local electrochemistry with high sensitivity and spatial resolution for a wide range of ionic systems, as well as ability to map local thermomechanical response.
International Nuclear Information System (INIS)
Hanasaki, Itsuo; Kawano, Satoyuki
2013-01-01
Motility of bacteria is usually recognized in the trajectory data and compared with Brownian motion, but the diffusion coefficient is insufficient to evaluate it. In this paper, we propose a method based on the large deviation principle. We show that it can be used to evaluate the non-Gaussian characteristics of model Escherichia coli motions and to distinguish combinations of the mean running duration and running speed that lead to the same diffusion coefficient. Our proposed method does not require chemical stimuli to induce the chemotaxis in a specific direction, and it is applicable to various types of self-propelling motions for which no a priori information of, for example, threshold parameters for run and tumble or head/tail direction is available. We also address the issue of the finite-sample effect on the large deviation quantities, but we propose to make use of it to characterize the nature of motility. (paper)
Geloni, G.; Saldin, E. L.; Schneidmiller, E. A.; Yurkov, M. V.
2004-08-01
An effective and practical technique based on the detection of the coherent synchrotron radiation (CSR) spectrum can be used to characterize the profile function of ultra-short bunches. The CSR spectrum measurement has an important limitation: no spectral phase information is available, and the complete profile function cannot be obtained in general. In this paper we propose to use constrained deconvolution method for bunch profile reconstruction based on a priori-known information about formation of the electron bunch. Application of the method is illustrated with practically important example of a bunch formed in a single bunch-compressor. Downstream of the bunch compressor the bunch charge distribution is strongly non-Gaussian with a narrow leading peak and a long tail. The longitudinal bunch distribution is derived by measuring the bunch tail constant with a streak camera and by using a priory available information about profile function.
International Nuclear Information System (INIS)
Hao Meng-Li; Xu Wei; Liu Di; Li Dong-Xi
2014-01-01
The extinction phenomenon induced by multiplicative non-Gaussian Lévy noise in a tumor growth model with immune response is discussed. Under the influence of the stochastic immune rate, the model is analyzed in terms of a stochastic differential equation with multiplicative noise. By means of the theory of the infinitesimal generator of Hunt processes, the escape probability, which is used to measure the noise-induced extinction probability of tumor cells, is explicitly expressed as a function of initial tumor cell density, stability index and noise intensity. Based on the numerical calculations, it is found that for different initial densities of tumor cells, noise parameters play opposite roles on the escape probability. The optimally selected values of the multiplicative noise intensity and the stability index are found to maximize the escape probability. (general)
Hu, D. L.; Liu, X. B.
Both periodic loading and random forces commonly co-exist in real engineering applications. However, the dynamic behavior, especially dynamic stability of systems under parametric periodic and random excitations has been reported little in the literature. In this study, the moment Lyapunov exponent and stochastic stability of binary airfoil under combined harmonic and non-Gaussian colored noise excitations are investigated. The noise is simplified to an Ornstein-Uhlenbeck process by applying the path-integral method. Via the singular perturbation method, the second-order expansions of the moment Lyapunov exponent are obtained, which agree well with the results obtained by the Monte Carlo simulation. Finally, the effects of the noise and parametric resonance (such as subharmonic resonance and combination additive resonance) on the stochastic stability of the binary airfoil system are discussed.
International Nuclear Information System (INIS)
Geloni, G.; Saldin, E.L.; Schneidmiller, E.A.; Yurkov, M.V.
2004-01-01
An effective and practical technique based on the detection of the coherent synchrotron radiation (CSR) spectrum can be used to characterize the profile function of ultra-short bunches. The CSR spectrum measurement has an important limitation: no spectral phase information is available, and the complete profile function cannot be obtained in general. In this paper we propose to use constrained deconvolution method for bunch profile reconstruction based on a priori-known information about formation of the electron bunch. Application of the method is illustrated with practically important example of a bunch formed in a single bunch-compressor. Downstream of the bunch compressor the bunch charge distribution is strongly non-Gaussian with a narrow leading peak and a long tail. The longitudinal bunch distribution is derived by measuring the bunch tail constant with a streak camera and by using a priory available information about profile function
Cecinati, F.; Wani, O.; Rico-Ramirez, M. A.
2017-11-01
Merging radar and rain gauge rainfall data is a technique used to improve the quality of spatial rainfall estimates and in particular the use of Kriging with External Drift (KED) is a very effective radar-rain gauge rainfall merging technique. However, kriging interpolations assume Gaussianity of the process. Rainfall has a strongly skewed, positive, probability distribution, characterized by a discontinuity due to intermittency. In KED rainfall residuals are used, implicitly calculated as the difference between rain gauge data and a linear function of the radar estimates. Rainfall residuals are non-Gaussian as well. The aim of this work is to evaluate the impact of applying KED to non-Gaussian rainfall residuals, and to assess the best techniques to improve Gaussianity. We compare Box-Cox transformations with λ parameters equal to 0.5, 0.25, and 0.1, Box-Cox with time-variant optimization of λ, normal score transformation, and a singularity analysis technique. The results suggest that Box-Cox with λ = 0.1 and the singularity analysis is not suitable for KED. Normal score transformation and Box-Cox with optimized λ, or λ = 0.25 produce satisfactory results in terms of Gaussianity of the residuals, probability distribution of the merged rainfall products, and rainfall estimate quality, when validated through cross-validation. However, it is observed that Box-Cox transformations are strongly dependent on the temporal and spatial variability of rainfall and on the units used for the rainfall intensity. Overall, applying transformations results in a quantitative improvement of the rainfall estimates only if the correct transformations for the specific data set are used.
Non-Gaussian wave packet dynamics in anharmonic potential: Cumulant expansion treatment
International Nuclear Information System (INIS)
Toutounji, Mohamad
2015-01-01
This manuscript utilizes cumulant expansion as an alternative algebraic approach to evaluating integrals and solving a system of nonlinear differential equations for probing anharmonic dynamics in condensed phase systems using Morse oscillator. These integrals and differential equations become harder to solve as the anharmonicity of the system goes beyond that of Morse oscillator description. This algebraic approach becomes critically important in case of Morse oscillator as it tends to exhibit divergent dynamics and numerical uncertainties at low temperatures. The autocorrelation function is calculated algebraically and compared to the exact one for they match perfectly. It is also compared to the approximate autocorrelation function using the differential equations technique reported in Toutounji (2014) for weak and strong electron–phonon coupling cases. It is found that the present cumulant method is more efficient, and easier to use, than the exact expression. Deviation between the approximate autocorrelation function and the exact autocorrelation function starts to arise as the electron–phonon coupling strength increases. The autocorrelation function obtained using cumulants identically matches the exact autocorrelation function, thereby surpassing the approach presented in Toutounji (2014). The advantage of the present methodology is its applicability to various types of electron–phonon coupling cases. Additionally, the herein approach only uses algebraic techniques, thereby avoiding both the divergence integral and solving a set of linear first- and second-order partial differential equations as was done in previous work. Model calculations are presented to demonstrate the accuracy of the herein work
Probing Local Ionic Dynamics in Functional Oxides: From Nanometer to Atomic Scale
Kalinin, Sergei
2014-03-01
Vacancy-mediated electrochemical reactions in oxides underpin multiple applications ranging from electroresistive memories, to chemical sensors to energy conversion systems such as fuel cells. Understanding the functionality in these systems requires probing reversible (oxygen reduction/evolution reaction) and irreversible (cathode degradation and activation, formation of conductive filaments) electrochemical processes. In this talk, I summarize recent advances in probing and controlling these transformations locally on nanometer level using scanning probe microscopy. The localized tip concentrates the electric field in the nanometer scale volume of material, inducing local transition. Measured simultaneously electromechanical response (piezoresponse) or current (conductive AFM) provides the information on the bias-induced changes in material. Here, I illustrate how these methods can be extended to study local electrochemical transformations, including vacancy dynamics in oxides such as titanates, LaxSr1-xCoO3, BiFeO3, and YxZr1-xO2. The formation of electromechanical hysteresis loops and their bias-, temperature- and environment dependences provide insight into local electrochemical mechanisms. In materials such as lanthanum-strontium cobaltite, mapping both reversible vacancy motion and vacancy ordering and static deformation is possible, and can be corroborated by post mortem STEM/EELS studies. In ceria, a broad gamut of electrochemical behaviors is observed as a function of temperature and humidity. The possible strategies for elucidation ionic motion at the electroactive interfaces in oxides using high-resolution electron microscopy and combined ex-situ and in-situ STEM-SPM studies are discussed. In the second part of the talk, probing electrochemical phenomena on in-situ grown surfaces with atomic resolution is illustrated. I present an approach based on the multivariate statistical analysis of the coordination spheres of individual atoms to reveal
Gravitational-wave localization alone can probe origin of stellar-mass black hole mergers.
Bartos, I; Haiman, Z; Marka, Z; Metzger, B D; Stone, N C; Marka, S
2017-10-10
The recent discovery of gravitational waves from stellar-mass binary black hole mergers by the Laser Interferometer Gravitational-wave Observatory opened the door to alternative probes of stellar and galactic evolution, cosmology and fundamental physics. Probing the origin of binary black hole mergers will be difficult due to the expected lack of electromagnetic emission and limited localization accuracy. Associations with rare host galaxy types-such as active galactic nuclei-can nevertheless be identified statistically through spatial correlation. Here we establish the feasibility of statistically proving the connection between binary black hole mergers and active galactic nuclei as hosts, even if only a sub-population of mergers originate from active galactic nuclei. Our results are the demonstration that the limited localization of gravitational waves, previously written off as not useful to distinguish progenitor channels, can in fact contribute key information, broadening the range of astrophysical questions probed by binary black hole observations.Binary black hole mergers have recently been observed through the detection of gravitational wave signatures. The authors demonstrate that their association with active galactic nuclei can be made through a statistical spatial correlation.
Matsui, Fumihiko; Matsushita, Tomohiro; Daimon, Hiroshi
2018-06-01
The local atomic structure around a specific element atom can be recorded as a photoelectron diffraction pattern. Forward focusing peaks and diffraction rings around them indicate the directions and distances from the photoelectron emitting atom to the surrounding atoms. The state-of-the-art holography reconstruction algorithm enables us to image the local atomic arrangement around the excited atom in a real space. By using circularly polarized light as an excitation source, the angular momentum transfer from the light to the photoelectron induces parallax shifts in these diffraction patterns. As a result, stereographic images of atomic arrangements are obtained. These diffraction patterns can be used as atomic-site-resolved probes for local electronic structure investigation in combination with spectroscopy techniques. Direct three-dimensional atomic structure visualization and site-specific electronic property analysis methods are reviewed. Furthermore, circular dichroism was also found in valence photoelectron and Auger electron diffraction patterns. The investigation of these new phenomena provides hints for the development of new techniques for local structure probing.
Contribution of local probes in the understanding of mechanical effect on localized corrosion
International Nuclear Information System (INIS)
Vignal, Vincent; Oltra, Roland; Mary, Nicolas
2004-01-01
Understanding the actual effects of mechanical stresses on the processes leading to pitting corrosion necessitates to develop both a mechanical approach and electrochemical experiments at a microscopic scale. Typical embrittlement can be observed after straining around MnS inclusions on a re-sulfurized 316 stainless steels and their corrosion sensitivity have been classified using the micro-capillary electrochemical cell technique. It has been shown that the numerical simulation of the location of stress gradients is possible before the local electrochemical analysis and could be a very interesting way to define the pitting susceptibility of micro-cracked areas during straining. (authors)
International Nuclear Information System (INIS)
Garnier, J.
1998-01-01
For a comprehensive approach of boiling crisis phenomenon in order to get more reliable predictions of critical heat flux in PWR core, a flow pattern study is under progress at CEA GRENOBLE (in a joint program with Electricite de France: EdF). The first aim is to get experimental results on flow structure in the range of thermal hydraulic parameters involved in the core of a PWR (pressure up to 16 MPa, heat flux about 1 MW/m 2 , mass velocity up to 5000 kg/s/m 2 . As critical heat flux is a local phenomenon and is the result of the flow development, the data has to be measured from the beginning of boiling until boiling crisis, and from the bulk flow until the boundary layer close to the heating walls. Therefore, these results will be useful in modeling not only boiling crisis phenomenon but also condensation in subcooled boiling, coalescence, splitting up, mass and energy transfers at interfaces, and so on. In a first step, the test section is a vertical tube 19.2 mm internal diameter with an axial uniform heat flux over a 3.5m length. The study is performed on the DEBORA loop with Freon 12 as coolant fluid. We assume that basic boiling phenomena (and the knowledge we get about them) only depend on the fluid properties by means of dimensionless parameters but not on the fluid itself. In a first part, we briefly recall that interfacial detection is the most important parameter of a flow pattern study. Therefore, the use of probes able to measure the Phase Indicator Function (P.I.F.) is necessary. A first study of flow conditions shows that the flow pattern is essentially a bubbly one with vapor particles of low diameter (about 300 clm) and high velocity (up to 7 m/s). These criteria induce that a multiple optical probe is the most appropriate tool provided we improve the technology. We detail the way to obtain probes able to detect small particles at high velocity. Each fiber is stretched to get a tip of 10 Clm with the cladding kept on 50 μm length which defines
Three-dimensional atom localization via probe absorption in a cascade four-level atomic system
Directory of Open Access Journals (Sweden)
Zeng Wei
2018-03-01
Full Text Available For an atomic system with cascade four-level type, a useful scheme about three-dimensional (3D atom localization is proposed. In our scheme the atomic system is coherently controlled by using a radio-frequency field to couple with two-folded levels under the condition of the existence of probe absorption. Our results show that detecting precision of 3D atom localization may be obviously improved by properly adjusting the frequency detuning and strength of the radio-frequency driving field. So our scheme could be helpful to realize 3D atom localization with high-efficiency and high-precision . In the field of laser cooling or the atom nano-lithography, our studies provide potential applications.
Three-dimensional atom localization via probe absorption in a cascade four-level atomic system
Zeng, Wei; Deng, Li; Chen, Aixi
2018-03-01
For an atomic system with cascade four-level type, a useful scheme about three-dimensional (3D) atom localization is proposed. In our scheme the atomic system is coherently controlled by using a radio-frequency field to couple with two-folded levels under the condition of the existence of probe absorption. Our results show that detecting precision of 3D atom localization may be obviously improved by properly adjusting the frequency detuning and strength of the radio-frequency driving field. So our scheme could be helpful to realize 3D atom localization with high-efficiency and high-precision . In the field of laser cooling or the atom nano-lithography, our studies provide potential applications.
Energy Technology Data Exchange (ETDEWEB)
Ravenni, Andrea; Liguori, Michele; Bartolo, Nicola [Dipartimento di Fisica e Astronomia ' G. Galilei' , Università degli Studi di Padova, via Marzolo 8, Padova, I-35131 Italy (Italy); Shiraishi, Maresuke, E-mail: ravenni@pd.infn.it, E-mail: liguori@pd.infn.it, E-mail: bartolo@pd.infn.it, E-mail: shiraishi-m@t.kagawa-nct.ac.jp [Department of General Education, National Institute of Technology, Kagawa College, 355 Chokushi-cho, Takamatsu, Kagawa, 761-8058 Japan (Japan)
2017-09-01
Cross-correlations between Cosmic Microwave Background (CMB) temperature and y -spectral distortion anisotropies have been previously proposed as a way to measure the local bispectrum parameter f {sub NL}{sup loc}. in a range of scales inaccessible to either CMB ( T , E ) bispectra or μ T correlations. This is useful e.g. to test scale dependence of primordial non-Gaussianity. Unfortunately, the primordial y T signal is strongly contaminated by the late-time correlation between the Integrated Sachs Wolfe and Sunyaev-Zel'dovich (SZ) effects. Moreover, SZ itself generates a large noise contribution in the y -parameter map. We consider two original ways to address these issues. In order to remove the bias due to the SZ-CMB temperature coupling, while also providing additional signal, we include in the analysis the cross-correlation between y -distortions and CMB polarization . In order to reduce the noise, we propose to clean the y -map by subtracting a SZ template, reconstructed via cross-correlation with external tracers (CMB and galaxy-lensing signals). We combine this SZ template subtraction with the previously suggested solution of directly masking detected clusters. Our final forecasts show that, using y -distortions, a PRISM-like survey can achieve 1σ( f {sub NL}{sup loc}.) = 300, while an ideal experiment will achieve 1σ( f {sub NL}{sup loc}.) = 130 with improvements of a factor between 2.1 and 3.8, depending on the considered survey, from adding the y E signal, and a further 20–30 % from template cleaning. These forecasts are much worse than current f {sub NL}{sup loc}. boundaries from Planck , but we stress that they refer to completely different scales.
Ester carbonyl vibration as a sensitive probe of protein local electric field.
Pazos, Ileana M; Ghosh, Ayanjeet; Tucker, Matthew J; Gai, Feng
2014-06-10
The ability to quantify the local electrostatic environment of proteins and protein/peptide assemblies is key to gaining a microscopic understanding of many biological interactions and processes. Herein, we show that the ester carbonyl stretching vibration of two non-natural amino acids, L-aspartic acid 4-methyl ester and L-glutamic acid 5-methyl ester, is a convenient and sensitive probe in this regard, since its frequency correlates linearly with the local electrostatic field for both hydrogen-bonding and non-hydrogen-bonding environments. We expect that the resultant frequency-electric-field map will find use in various applications. Furthermore, we show that, when situated in a non-hydrogen-bonding environment, this probe can also be used to measure the local dielectric constant (ε). For example, its application to amyloid fibrils formed by Aβ(16-22) revealed that the interior of such β-sheet assemblies has an ε value of approximately 5.6. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Directory of Open Access Journals (Sweden)
Junjie Ma
2018-02-01
Full Text Available Pollution accidents that occur in surface waters, especially in drinking water source areas, greatly threaten the urban water supply system. During water pollution source localization, there are complicated pollutant spreading conditions and pollutant concentrations vary in a wide range. This paper provides a scalable total solution, investigating a distributed localization method in wireless sensor networks equipped with mobile ultraviolet-visible (UV-visible spectrometer probes. A wireless sensor network is defined for water quality monitoring, where unmanned surface vehicles and buoys serve as mobile and stationary nodes, respectively. Both types of nodes carry UV-visible spectrometer probes to acquire in-situ multiple water quality parameter measurements, in which a self-adaptive optical path mechanism is designed to flexibly adjust the measurement range. A novel distributed algorithm, called Dual-PSO, is proposed to search for the water pollution source, where one particle swarm optimization (PSO procedure computes the water quality multi-parameter measurements on each node, utilizing UV-visible absorption spectra, and another one finds the global solution of the pollution source position, regarding mobile nodes as particles. Besides, this algorithm uses entropy to dynamically recognize the most sensitive parameter during searching. Experimental results demonstrate that online multi-parameter monitoring of a drinking water source area with a wide dynamic range is achieved by this wireless sensor network and water pollution sources are localized efficiently with low-cost mobile node paths.
Ma, Junjie; Meng, Fansheng; Zhou, Yuexi; Wang, Yeyao; Shi, Ping
2018-02-16
Pollution accidents that occur in surface waters, especially in drinking water source areas, greatly threaten the urban water supply system. During water pollution source localization, there are complicated pollutant spreading conditions and pollutant concentrations vary in a wide range. This paper provides a scalable total solution, investigating a distributed localization method in wireless sensor networks equipped with mobile ultraviolet-visible (UV-visible) spectrometer probes. A wireless sensor network is defined for water quality monitoring, where unmanned surface vehicles and buoys serve as mobile and stationary nodes, respectively. Both types of nodes carry UV-visible spectrometer probes to acquire in-situ multiple water quality parameter measurements, in which a self-adaptive optical path mechanism is designed to flexibly adjust the measurement range. A novel distributed algorithm, called Dual-PSO, is proposed to search for the water pollution source, where one particle swarm optimization (PSO) procedure computes the water quality multi-parameter measurements on each node, utilizing UV-visible absorption spectra, and another one finds the global solution of the pollution source position, regarding mobile nodes as particles. Besides, this algorithm uses entropy to dynamically recognize the most sensitive parameter during searching. Experimental results demonstrate that online multi-parameter monitoring of a drinking water source area with a wide dynamic range is achieved by this wireless sensor network and water pollution sources are localized efficiently with low-cost mobile node paths.
An improved tracking framework for ultrasound probe localization in image-guided radiosurgery
Directory of Open Access Journals (Sweden)
Ipsen Svenja
2016-09-01
Full Text Available Real-time target localization with ultrasound holds high potential for image guidance and motion compensation in radiosurgery due to its non-invasive image acquisition free from ionizing radiation. However, a two-step localization has to be performed when integrating ultrasound into the existing radiosurgery workflow. In addition to target localization inside the ultrasound volume, the probe itself has to be localized in order to transform the target position into treatment room coordinates. By adapting existing camera calibration tools, we have developed a method to extend the stereoscopic X-ray tracking system of a radiosurgery platform in order to locate objects such as marker geometries with six degrees of freedom. The calibration was performed with 0.1 mm reprojection error. By using the full area of the flat-panel detectors without pre-processing the extended software increased the tracking volume and resolution by up to 80%, substantially improving patient localization and marker detectability. Furthermore, marker-tracking showed sub-millimeter accuracy and rotational errors below 0.1°. This demonstrates that the developed extension framework can accurately localize marker geometries using an integrated X-ray system, establishing the link for the integration of real-time ultrasound image guidance into the existing system.
Investigating the micro-rheology of the vitreous humor using an optically trapped local probe
Watts, Fiona; Ean Tan, Lay; Wilson, Clive G.; Girkin, John M.; Tassieri, Manlio; Wright, Amanda J.
2014-01-01
We demonstrate that an optically trapped silica bead can be used as a local probe to measure the micro-rheology of the vitreous humor. The Brownian motion of the bead was observed using a fast camera and the micro-rheology determined by analysis of the time-dependent mean-square displacement of the bead. We observed regions of the vitreous that showed different degrees of viscoelasticity, along with the homogeneous and inhomogeneous nature of different regions. The motivation behind this study is to understand the vitreous structure, in particular changes due to aging, allowing more confident prediction of pharmaceutical drug behavior and delivery within the vitreous humor.
Investigating the micro-rheology of the vitreous humor using an optically trapped local probe
International Nuclear Information System (INIS)
Watts, Fiona; Wright, Amanda J; Tan, Lay Ean; Wilson, Clive G; Girkin, John M; Tassieri, Manlio
2014-01-01
We demonstrate that an optically trapped silica bead can be used as a local probe to measure the micro-rheology of the vitreous humor. The Brownian motion of the bead was observed using a fast camera and the micro-rheology determined by analysis of the time-dependent mean-square displacement of the bead. We observed regions of the vitreous that showed different degrees of viscoelasticity, along with the homogeneous and inhomogeneous nature of different regions. The motivation behind this study is to understand the vitreous structure, in particular changes due to aging, allowing more confident prediction of pharmaceutical drug behavior and delivery within the vitreous humor. (paper)
Development of an instantaneous local fuel-concentration measurement probe: an engine application
Guibert, P.; Boutar, Z.; Lemoyne, L.
2003-11-01
This work presents a new tool which can deliver instantaneous local measurements of fuel concentration in an engine cylinder with a high temporal resolution, particularly during compression strokes. Fuel concentration is represented by means of equivalence fuel-air ratio, i.e. the real engine mass ratio of fuel to air divided by the same ratio in ideal stoichiometry conditions. Controlling the mixture configuration for any strategy in a spark ignition engine and for auto-ignition combustion has a dominant effect on the subsequent processes of ignition, flame propagation and auto-ignition combustion progression, pollutant formation under lean or even stoichiometric operating conditions. It is extremely difficult, under a transient operation, to control the equivalence air/fuel ratio precisely at a required value and at the right time. This requires the development of a highly accurate equivalence air/fuel ratio control system and a tool to measure using crank angle (CA) resolution. Although non-intrusive laser techniques have considerable advantages, they are most of the time inappropriate due to their optical inaccessibility or the complex experimental set-up involved. Therefore, as a response to the demand for a relatively simple fuel-concentration measurement system a probe is presented that replaces a spark plug and allows the engine to run completely normally. The probe is based on hot-wire like apparatus, but involves catalytic oxidation at the wire surface. The development, characteristics and calibration of the probe are presented followed by applications to in-cylinder engine measurements.
International Nuclear Information System (INIS)
Euh, D.J.; Yun, B.J.; Song, C.H.; Kwon, T.S.; Chung, M.K.; Lee, U.C.
2000-01-01
The interfacial area concentration (IAC) is one of the most important parameters in the two-fluid model for two-phase flow analysis. The IAC can be measured by a local conductivity probe method that uses the difference of conductivity between water and air/steam. The number of sensors in the conductivity probe may be differently chosen by considering the flow regime of two-phase flow. The four sensor conductivity probe method predicts the IAC without any assumptions of the bubble shape. The local IAC can be obtained by measuring the three dimensional velocity vector elements at the measuring point, and the directional cosines of the sensors. The five sensor conductivity probe method proposed in this study is based on the four sensor probe method. With the five sensor probe, the local IAC for a given referred measuring area of the probe can be predicted more exactly. In this paper, the mathematical approach of the five sensor probe method for measuring the IAC is described, and a numerical simulation is carried out for ideal cap bubbles of which the sizes and locations are determined by a random number generator. (author)
Directory of Open Access Journals (Sweden)
Douglas Scott C
2007-01-01
Full Text Available We derive new fixed-point algorithms for the blind separation of complex-valued mixtures of independent, noncircularly symmetric, and non-Gaussian source signals. Leveraging recently developed results on the separability of complex-valued signal mixtures, we systematically construct iterative procedures on a kurtosis-based contrast whose evolutionary characteristics are identical to those of the FastICA algorithm of Hyvarinen and Oja in the real-valued mixture case. Thus, our methods inherit the fast convergence properties, computational simplicity, and ease of use of the FastICA algorithm while at the same time extending this class of techniques to complex signal mixtures. For extracting multiple sources, symmetric and asymmetric signal deflation procedures can be employed. Simulations for both noiseless and noisy mixtures indicate that the proposed algorithms have superior finite-sample performance in data-starved scenarios as compared to existing complex ICA methods while performing about as well as the best of these techniques for larger data-record lengths.
Energy Technology Data Exchange (ETDEWEB)
Behbahani, Siavosh R.; /SLAC /Stanford U., Phys. Dept. /Boston U.; Dymarsky, Anatoly; /Princeton, Inst. Advanced Study; Mirbabayi, Mehrdad; /New York U., CCPP /New York U.; Senatore, Leonardo; /Stanford U., Phys. Dept. /KIPAC, Menlo Park
2012-06-06
We apply the Effective Field Theory of Inflation to study the case where the continuous shift symmetry of the Goldstone boson {pi} is softly broken to a discrete subgroup. This case includes and generalizes recently proposed String Theory inspired models of Inflation based on Axion Monodromy. The models we study have the property that the 2-point function oscillates as a function of the wavenumber, leading to oscillations in the CMB power spectrum. The non-linear realization of time diffeomorphisms induces some self-interactions for the Goldstone boson that lead to a peculiar non-Gaussianity whose shape oscillates as a function of the wavenumber. We find that in the regime of validity of the effective theory, the oscillatory signal contained in the n-point correlation functions, with n > 2, is smaller than the one contained in the 2-point function, implying that the signature of oscillations, if ever detected, will be easier to find first in the 2-point function, and only then in the higher order correlation functions. Still the signal contained in higher-order correlation functions, that we study here in generality, could be detected at a subleading level, providing a very compelling consistency check for an approximate discrete shift symmetry being realized during inflation.
International Nuclear Information System (INIS)
Kang-Kang, Wang; Xian-Bin, Liu; Yu, Zhou
2015-01-01
In this paper, the stability and stochastic resonance (SR) phenomenon induced by the multiplicative periodic signal for a metapopulation system driven by the additive Gaussian noise, multiplicative non-Gaussian noise and noise correlation time is investigated. By using the fast descent method, unified colored noise approximation and McNamara and Wiesenfeld’s SR theory, the analytical expressions of the stationary probability distribution function and signal-to-noise ratio (SNR) are derived in the adiabatic limit. Via numerical calculations, each effect of the addictive noise intensity, the multiplicative noise intensity and the correlation time upon the steady state probability distribution function and the SNR is discussed, respectively. It is shown that multiplicative, additive noises and the departure parameter from the Gaussian noise can all destroy the stability of the population system. However, the noise correlation time can consolidate the stability of the system. On the other hand, the correlation time always plays an important role in motivating the SR and enhancing the SNR. Under different parameter conditions of the system, the multiplicative, additive noises and the departure parameter can not only excite SR phenomenon, but also restrain the SR phenomenon, which demonstrates the complexity of different noises upon the nonlinear system. (paper)
First local electrode atom probe analysis of magnetite (Fe3O4)
International Nuclear Information System (INIS)
Kuhlman, K.R.; Kelly, T.F.; Miller, M.K.
2004-01-01
Full text: We have successfully fabricated atom probe samples of a metamorphic magnetite and performed an analysis of one of these samples using a local electrode atom probe (LEAP). This particular magnetite, previously designated LP204-1, was extracted from a polymetamorphosed, granulite-facies marble and contains grain scale heterogeneity in its oxygen isotope ratios. Crystals of LP204-1 contain a high number density of nanometer-scale, disk-shaped Al-Mn-Fe-spinel precipitates making this magnetite particularly attractive for demonstrating the capabilities of the LEAP with regard to geological materials. Field ion microscope images of these magnetite crystals show precipitate size and morphology that agrees with previous results. A sample of LP-204-1 was analyzed in the LEAP, resulting in a cylindrical analyzed volume approx. 26 nm in diameter and 21 nm high. The mass spectrum contained nearly 106,000 atoms, 97.1 % of which were identified. Peaks for singly, doubly and triply ionized species were fully resolved. The analysis volume appeared to be purely magnetite, i.e. no precipitates were observed. If it is assumed that 77 % of the ions in the peak at 16 are O 2 ++ rather than O+, the stoichiometry measured for this sample using electron probe microanalysis is achieved. The high fraction of O 2 ++ can be explained by lack of a peak for O ++ and significant peaks for FeO x indicating a relatively low field strength, which in turn favors molecular ions. This work is an encouraging beginning for analysis of geological materials in atom probes. Refs. 4 (author)
International Nuclear Information System (INIS)
Yan, Xiu-Fang; Chen, Zeng-Ping; Cui, Yin-Yin; Hu, Yuan-Liang; Yu, Ru-Qin
2016-01-01
PEBBLE (probe encapsulated by biologically localized embedding) nanosensor encapsulating an intensity-based fluorescence indicator and an inert reference fluorescence dye inside the pores of stable matrix can be used as a generalized wavelength-ratiometric probe. However, the lack of an efficient quantitative model render the choices of inert reference dyes and intensity-based fluorescence indicators used in PEBBLEs based generalized wavelength-ratiometric probes rather limited. In this contribution, an extended quantitative fluorescence model was derived specifically for generalized wavelength-ratiometric probes based on PEBBLE technique (QFM GRP ) with a view to simplify the design of PEBBLEs and hence further extend their application potentials. The effectiveness of QFM GRP has been tested on the quantitative determination of free Ca 2+ in both simulated and real turbid media using a Ca 2+ sensitive PEBBLE nanosensor encapsulating Rhod-2 and eosin B inside the micropores of stable polyacrylamide matrix. Experimental results demonstrated that QFM GRP could realize precise and accurate quantification of free Ca 2+ in turbid samples, even though there is serious overlapping between the fluorescence excitation peaks of eosin B and Ca 2+ bound Rhod-2. The average relative predictive error value of QFM GRP for the test simulated turbid samples was 5.9%, about 2–4 times lower than the corresponding values of partial least squares calibration model and the empirical ratiometric model based on the ratio of fluorescence intensities at the excitation peaks of Ca 2+ bound Rhod-2 and eosin B. The recovery rates of QFM GRP for the real and spiked turbid samples varied from 93.1% to 101%, comparable to the corresponding results of atomic absorption spectrometry. - Highlights: • An advanced model was derived for generalized wavelength-ratiometric PEBBLEs. • The model can simplify the design of generalized wavelength-ratiometric PEBBLEs. • The model realized accurate
Selective probe of the morphology and local vibrations at carbon nanoasperities
Energy Technology Data Exchange (ETDEWEB)
Fujimori, Toshihiko; Endo, Morinobu; Kaneko, Katsumi [Research Center for Exotic Nanocarbons (JST), Shinshu University, 4-17-1, Wakasato, Nagano-city 380-8553 (Japan); Urita, Koki; Moriguchi, Isamu [Department of Applied Chemistry, Faculty of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki-shi, Nagasaki 852-8521 (Japan); Tomanek, David [Physics and Astronomy Department, Michigan State University, East Lansing, Michigan 48824 (United States); Ohba, Tomonori [Department of Chemistry, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan)
2012-02-14
We introduce a way to selectively probe local vibration modes at nanostructured asperities such as tips of carbon nanohorns. Our observations benefit from signal amplification in surface-enhanced Raman scattering (SERS) at sites near a silver surface. We observe nanohorn tip vibration modes in the range 200-500 cm{sup -1}, which are obscured in regular Raman spectra. Ab initio density functional calculations assign modes in this frequency range to local vibrations at the nanohorn cap resembling the radial breathing mode of fullerenes. Careful interpretation of our SERS spectra indicates presence of caps with 5 or 6 pentagons, which are chemically the most active sites. Changes in the peak intensities and frequencies with time indicate that exposure to laser irradiation may cause structural rearrangements at the cap.
Infrared Hollow Optical Fiber Probe for Localized Carbon Dioxide Measurement in Respiratory Tracts.
Katagiri, Takashi; Shibayama, Kyosuke; Iida, Takeru; Matsuura, Yuji
2018-03-27
A real-time gas monitoring system based on optical absorption spectroscopy is proposed for localized carbon dioxide (CO₂) measurement in respiratory tracts. In this system, a small gas cell is attached to the end of a hollow optical fiber that delivers mid-infrared light with small transmission loss. The diameters of the fiber and the gas cell are smaller than 1.2 mm so that the probe can be inserted into a working channel of common bronchoscopes. The dimensions of the gas cell are designed based on absorption spectra of CO₂ standard gases in the 4.2 μm wavelength region, which are measured using a Fourier-transform infrared spectrometer. A miniature gas cell that is comprised of a stainless-steel tube with slots for gas inlet and a micro-mirror is fabricated. A compact probing system with a quantum cascade laser (QCL) light source is built using a gas cell with a hollow optical fiber for monitoring CO₂ concentration. Experimental results using human breaths show the feasibility of the system for in-situ measurement of localized CO₂ concentration in human airways.
Infrared Hollow Optical Fiber Probe for Localized Carbon Dioxide Measurement in Respiratory Tracts
Directory of Open Access Journals (Sweden)
Takashi Katagiri
2018-03-01
Full Text Available A real-time gas monitoring system based on optical absorption spectroscopy is proposed for localized carbon dioxide (CO2 measurement in respiratory tracts. In this system, a small gas cell is attached to the end of a hollow optical fiber that delivers mid-infrared light with small transmission loss. The diameters of the fiber and the gas cell are smaller than 1.2 mm so that the probe can be inserted into a working channel of common bronchoscopes. The dimensions of the gas cell are designed based on absorption spectra of CO2 standard gases in the 4.2 μm wavelength region, which are measured using a Fourier-transform infrared spectrometer. A miniature gas cell that is comprised of a stainless-steel tube with slots for gas inlet and a micro-mirror is fabricated. A compact probing system with a quantum cascade laser (QCL light source is built using a gas cell with a hollow optical fiber for monitoring CO2 concentration. Experimental results using human breaths show the feasibility of the system for in-situ measurement of localized CO2 concentration in human airways.
Energy Technology Data Exchange (ETDEWEB)
Bender, P., E-mail: nano@p-bender.de; Tschöpe, A., E-mail: antsch@mx.uni-saarland.de; Birringer, R., E-mail: r.birringer@nano.uni-saarland.de
2014-12-15
The local mechanical coupling of ferromagnetic nanorods in hydrogels was characterized by magnetization measurements. Nickel nanorods were synthesized by the AAO-template method and embedded in gelatine hydrogels with mechanically soft or hard matrix properties determined by the gelatine weight fraction. By applying a homogeneous magnetic field during gelation the nanorods were aligned along the field resulting in uniaxially textured ferrogels. The magnetization curves of the soft ferrogel exhibited not only important similarities but also characteristic differences as compared to the hard ferrogel. The hystereses measured in a field parallel to the texture axis were almost identical for both samples indicating effective coupling of the nanorods with the polymer network. By contrast, measurements in a magnetic field perpendicular to the texture axis revealed a much higher initial susceptibility of the soft as compared to the hard ferrogel. This difference was attributed to the additional rotation of the nanorods allowed by the reduced shear modulus in the soft ferrogel matrix. Two methods for data analysis were presented which enabled us to determine the shear modulus of the gelatine matrix which was interpreted as a local rather than macroscopic quantity in consideration of the nanoscale of the probe particles. - Highlights: • Nanorods are embedded as magnetic probes in gelatine gels. • Elastic rotation of the rods can be induced by applying a homogeneous magnetic field. • Rod rotation has significant influence on the magnetization curves. • Two methods are presented to estimate the shear modulus of the matrix from the magnetization curves.
International Nuclear Information System (INIS)
Tian Daogui; Sun Licheng; Yan Changqi; Liu Guoqiang
2013-01-01
In order to get more local interfacial information as well as to further comprehend the intrinsic mechanism of two-phase flow under rolling condition, a method was proposed to measure the local parameters by using optical probes under rolling condition in this paper. An experimental investigation of two-phase flow under rolling condition was conducted using the probe fabricated by the authors. It is verified that the probe method is feasible to measure the local parameters in two'-phase flow under rolling condition. The results show that the interfacial parameters distribution near wall region has a distinct periodicity due to the rolling motion. The averaged deviation of the void fraction measured by the probe from that obtained from measured pressure drop is about 8%. (authors)
Energy Technology Data Exchange (ETDEWEB)
Farhang, Amin; Khosroshahi, Habib G.; Javadi, Atefeh; Molaeinezhad, Alireza; Tavasoli, Saeed; Habibi, Farhang; Kourkchi, Ehsan; Rezaei, Sara; Saberi, Maryam [School of Astronomy, Institute for Research in Fundamental Sciences (IPM), PO Box 19395-5746 Tehran (Iran, Islamic Republic of); Van Loon, Jacco Th.; Bailey, Mandy [Astrophysics Group, Lennard-Jones Laboratories, Keele University, Staffordshire ST5 5BG (United Kingdom); Hardy, Liam, E-mail: a.farhang@ipm.ir [Isaac Newton Group, Apartado 321, E-38700 Santa Cruz de La Palma (Spain)
2015-02-10
We present a new high signal-to-noise ratio spectroscopic survey of the Northern hemisphere to probe the Local Bubble and its surroundings using the λ5780 Å and λ5797 Å diffuse interstellar bands (DIBs). We observed 432 sightlines to a distance of 200 pc over a duration of three years. In this study, we establish the λ5780 and λ5797 correlations with Na I, Ca II and E {sub B-V}, for both inside and outside the Local Bubble. The correlations show that among all neutral and ionized atoms, the correlation between Ca II and λ5780 is stronger than its correlation with λ5797, suggesting that λ5780 is more associated with regions where Ca{sup +} is more abundant. We study the λ5780 correlation with λ5797, which shows a tight correlation within and outside the Local Bubble. In addition, we investigate the DIB properties in UV irradiated and UV shielded regions. We find that, within and beyond the Local Bubble, λ5797 is located in denser parts of clouds, protected from UV irradiation, while λ5780 is located in the low-density regions of clouds.
Local charge trapping in Ge nanoclustersdetected by Kelvin probe force microscopy
Energy Technology Data Exchange (ETDEWEB)
Kondratenko, S.V., E-mail: kondr@univ.kiev.ua [Taras Shevchenko National University of Kyiv, 64/13 Volodymyrska Str., 01601, Kyiv (Ukraine); Lysenko, V.S. [Institute of Semiconductor Physics, 41 Prospect Nauki, 03028, Kyiv (Ukraine); Kozyrev, Yu. N. [O.O. Chuiko Institute of Surface Chemistry, 17 GeneralaNaumova Str. 03164, Kiev (Ukraine); Kratzer, M. [Institute of Physics, MontanuniversitätLeoben, Franz Josef Str. 18, A-8700, Leoben (Austria); Storozhuk, D.P.; Iliash, S.A. [Taras Shevchenko National University of Kyiv, 64/13 Volodymyrska Str., 01601, Kyiv (Ukraine); Czibula, C. [Institute of Physics, MontanuniversitätLeoben, Franz Josef Str. 18, A-8700, Leoben (Austria); Teichert, C., E-mail: teichert@unileoben.ac.at [Institute of Physics, MontanuniversitätLeoben, Franz Josef Str. 18, A-8700, Leoben (Austria)
2016-12-15
The understanding of local charge trapping on the nanoscale is crucial for the design of novel electronic devices and photodetectors based on SiGe nanoclusters (NCs). Here, the local spatial distribution of the surface potential of the Ge NCs was detected using Kelvin probe force microscopy (KPFM). Different surface potentials between Ge NCs and the wetting layer (WL) surface were detected at room temperature. Changes of the local contact potential differences (CPD) were studied after injection of electrons or holes into single Ge NCs on top of the Si layer using a conductive atomic force microscopy tip. The CPD image contrast was increased after electron injection by applying a forward bias to the n-tip/i-Ge NC/p-Si junction. Injecting holes into a single Ge NC was also accompanied by filling of two-dimensional states in the surrounding region, which is governed by leakage currents through WL or surface states and Coulomb charging effects. A long retention time of holes trapped by the Ge NC was found.
Intraoperative use of gamma-detecting probes to localize neuroendocrine tumor
International Nuclear Information System (INIS)
Adams, S.; Baum, R.P.
2000-01-01
Neuroendocrine tumors are characterized by the expression of different peptides and biogenic amines. These rare tumors tend to grow slowly and are notoriously difficult to localize, at least in the early stages. Surgical removal is the only definitive therapeutic option for neuroendocrine tumors and relief from hyper functional status. The effectiveness of surgical treatment is invariably dependent upon the complete surgical excision of all tumor tissue, because microscopic and occult disease not readily seen by the surgeon may remain in sit, leading to shortened survival. Radio guided surgery (RGS) is an intraoperative technique that enables the surgeon to localize radiolabelled tissue based on the characteristics of the various tissues. For imaging recurrent MTC (Medullary Thyroid Cancer) many radiopharmaceuticals have been used to visualize tumor sites, but none of them has shown excellent sensitivity. Preoperative somatostatin receptor scintigraphy and intraoperative RGS in patients with recurrent MTC demonstrate only part of the tumor sites and cannot visualize small tumor sites (less than 10 mm). In patients with recurrent MTC, intraoperative gamma probe examination is able to localize over 30% more tumor lesions when compared with conventional preoperative imaging modalities and surgical findings. In addition to scintigraphy of the adrenal glands by precursors of adrenal hormones, imaging with a radiolabelled somatostatin analogue is possible; however ( 111 In-DTPA-D-Phe 1 )-pentetreotide is not specific for any adrenal disease or function and the relatively high radioligand accumulation in the kidneys limited the use for detection of tumors in the area of the adrenal glands
Intraoperative use of gamma-detecting probes to localize neuroendocrine tumor
Energy Technology Data Exchange (ETDEWEB)
Adams, S. [Johann Wolfgang Goethe Univ., Frankfurt/Main (Germany). Medical Center, Dept. of Nuclear Medicine; Baum, R.P. [Zentralklinik Bad Berka GmbH, Bad Berka (Germany). Clinic of Nuclear Medicine/PET Center
2000-03-01
Neuroendocrine tumors are characterized by the expression of different peptides and biogenic amines. These rare tumors tend to grow slowly and are notoriously difficult to localize, at least in the early stages. Surgical removal is the only definitive therapeutic option for neuroendocrine tumors and relief from hyper functional status. The effectiveness of surgical treatment is invariably dependent upon the complete surgical excision of all tumor tissue, because microscopic and occult disease not readily seen by the surgeon may remain in sit, leading to shortened survival. Radio guided surgery (RGS) is an intraoperative technique that enables the surgeon to localize radiolabelled tissue based on the characteristics of the various tissues. For imaging recurrent MTC (Medullary Thyroid Cancer) many radiopharmaceuticals have been used to visualize tumor sites, but none of them has shown excellent sensitivity. Preoperative somatostatin receptor scintigraphy and intraoperative RGS in patients with recurrent MTC demonstrate only part of the tumor sites and cannot visualize small tumor sites (less than 10 mm). In patients with recurrent MTC, intraoperative gamma probe examination is able to localize over 30% more tumor lesions when compared with conventional preoperative imaging modalities and surgical findings. In addition to scintigraphy of the adrenal glands by precursors of adrenal hormones, imaging with a radiolabelled somatostatin analogue is possible; however ({sup 111}In-DTPA-D-Phe{sup 1})-pentetreotide is not specific for any adrenal disease or function and the relatively high radioligand accumulation in the kidneys limited the use for detection of tumors in the area of the adrenal glands.
Equilibration of a strongly interacting plasma: holographic analysis of local and nonlocal probes
Directory of Open Access Journals (Sweden)
Bellantuono Loredana
2016-01-01
Full Text Available The relaxation of a strongly coupled plasma towards the hydrodynamic regime is studied by analyzing the evolution of local and nonlocal observables in the holographic approach. The system is driven in an initial anisotropic and far-from equilibrium state through an impulsive time-dependent deformation (quench of the boundary spacetime geometry. Effective temperature and entropy density are related to the position and area of a black hole horizon, which has formed as a consequence of the distortion. The behavior of stress-energy tensor, equal-time correlation functions and Wilson loops of different shapes is examined, and a hierarchy among their thermalization times emerges: probes involving shorter length scales thermalize faster.
International Nuclear Information System (INIS)
Hagelberg, F.; Das, T.P.; Speidel, K.
1993-01-01
The transient field phenomenon has been ascribed to a polarization transfer between the electrons of the ionic projectiles and the surplus of majority spin electrons of the ferromagnetic host over the minority spin electrons. Earlier attempts to explain this crucial process failed to account for the order of magnitude of the experimentally observed transient field strengths. A recent model which proposes spin exchange scattering between bound projectile electrons and quasifree host electrons as the mechanism of polarization transfer arrives at the correct orders of magnitude but is in conflict with the weak velocity dependence of the experimental polarization, exhibiting a strongly decreasing behavior with increasing velocity. The new model presented here proposes spin exchange between the ionic shell and localized electrons of the ferromagnet as a more adequate approach to the problem. It is shown that calculations involving hydrogenlike ions explain the size of the experimentally observed polarization effects as well as their velocity dependence for various ion probes traversing thin iron foils
Local probe studies on lattice distortions and electronic correlations in manganites
lopes, Armandina; Correia, João Guilherme
This thesis presents an experimental study on lattice distortions and electronic correlations in colossal magnetoresistive magnetic oxides. The Perturbed Angular Correlation local probe technique is used to study selected manganite systems in order to obtain relevant insight into microscopic phenomena responsible for their macroscopic pr operties. Complementary structural, magnetic and electric characterization was performed. The work is focused on the following aspects: \\\\Lattice distortions and polaron clusters in LaMnO$_{3+ \\Delta}$ system. A study of the electric field gradi ent and magnetic hyperfine field was performed in representative samples of the LaMnO$_{3+ \\Delta}$ system, and correlated with macroscopic information obtained in the same samples. Particular attention was given to the LaMnO$_{3.12}$ sample since this compound is a prototype of a ferromagnetic-insulat or manganite, presenting a rhombohedric- orthorhombic structural phase transition near room temperature. We found that random distribu...
Olsen, M. K.
2017-02-01
We propose and analyze a pumped and damped Bose-Hubbard dimer as a source of continuous-variable Einstein-Podolsky-Rosen (EPR) steering with non-Gaussian statistics. We use and compare the results of the approximate truncated Wigner and the exact positive-P representation to calculate and compare the predictions for intensities, second-order quantum correlations, and third- and fourth-order cumulants. We find agreement for intensities and the products of inferred quadrature variances, which indicate that states demonstrating the EPR paradox are present. We find clear signals of non-Gaussianity in the quantum states of the modes from both the approximate and exact techniques, with quantitative differences in their predictions. Our proposed experimental configuration is extrapolated from current experimental techniques and adds another apparatus to the current toolbox of quantum atom optics.
Park, Subok; Gallas, Bradon D; Badano, Aldo; Petrick, Nicholas A; Myers, Kyle J
2007-04-01
A previous study [J. Opt. Soc. Am. A22, 3 (2005)] has shown that human efficiency for detecting a Gaussian signal at a known location in non-Gaussian distributed lumpy backgrounds is approximately 4%. This human efficiency is much less than the reported 40% efficiency that has been documented for Gaussian-distributed lumpy backgrounds [J. Opt. Soc. Am. A16, 694 (1999) and J. Opt. Soc. Am. A18, 473 (2001)]. We conducted a psychophysical study with a number of changes, specifically in display-device calibration and data scaling, from the design of the aforementioned study. Human efficiency relative to the ideal observer was found again to be approximately 5%. Our variance analysis indicates that neither scaling nor display made a statistically significant difference in human performance for the task. We conclude that the non-Gaussian distributed lumpy background is a major factor in our low human-efficiency results.
Xu, Xue-Xiang; Yuan, Hong-Chun; Wang, Yan
2014-07-01
We investigate the nonclassical properties of arbitrary number photon annihilation-then-creation operation (AC) and creation-then-annihilation operation (CA) to the thermal state (TS), whose normalization factors are related to the polylogarithm function. Then we compare their quantum characters, such as photon number distribution, average photon number, Mandel Q-parameter, purity and the Wigner function. Because of the noncommutativity between the annihilation operator and the creation operator, the ACTS and the CATS have different nonclassical properties. It is found that nonclassical properties are exhibited more strongly after AC than after CA. In addition we also examine their non-Gaussianity. The result shows that the ACTS can present a slightly bigger non-Gaussianity than the CATS.
International Nuclear Information System (INIS)
Xu Xue-Xiang; Wang Yan; Yuan Hong-Chun
2014-01-01
We investigate the nonclassical properties of arbitrary number photon annihilation-then-creation operation (AC) and creation-then-annihilation operation (CA) to the thermal state (TS), whose normalization factors are related to the polylogarithm function. Then we compare their quantum characters, such as photon number distribution, average photon number, Mandel Q-parameter, purity and the Wigner function. Because of the noncommutativity between the annihilation operator and the creation operator, the ACTS and the CATS have different nonclassical properties. It is found that nonclassical properties are exhibited more strongly after AC than after CA. In addition we also examine their non-Gaussianity. The result shows that the ACTS can present a slightly bigger non-Gaussianity than the CATS. (general)
International Nuclear Information System (INIS)
Rodriguez, Yeinzon; Valenzuela-Toledo, Cesar A.
2010-01-01
We calculate the trispectrum T ζ of the primordial curvature perturbation ζ, generated during a slow-roll inflationary epoch by considering a two-field quadratic model of inflation with canonical kinetic terms. We consider loop contributions as well as tree-level terms, and show that it is possible to attain very high, including observable, values for the level of non-Gaussianity τ NL if T ζ is dominated by the one-loop contribution. Special attention is paid to the claim in J. Cosmol. Astropart. Phys. 02 (2009) 017 that, in the model studied in this paper and for the specific inflationary trajectory we choose, the quantum fluctuations of the fields overwhelm the classical evolution. We argue that such a claim actually does not apply to our model, although more research is needed in order to understand the role of quantum diffusion. We also consider the probability that an observer in an ensemble of realizations of the density field sees a non-Gaussian distribution. In that respect, we show that the probability associated to the chosen inflationary trajectory is non-negligible. Finally, the levels of non-Gaussianity f NL and τ NL in the bispectrum B ζ and trispectrum T ζ of ζ, respectively, are also studied for the case in which ζ is not generated during inflation.
Zhang, Guangwen; Wang, Shuangshuang; Wen, Didi; Zhang, Jing; Wei, Xiaocheng; Ma, Wanling; Zhao, Weiwei; Wang, Mian; Wu, Guosheng; Zhang, Jinsong
2016-12-09
Water molecular diffusion in vivo tissue is much more complicated. We aimed to compare non-Gaussian diffusion models of diffusion-weighted imaging (DWI) including intra-voxel incoherent motion (IVIM), stretched-exponential model (SEM) and Gaussian diffusion model at 3.0 T MRI in patients with rectal cancer, and to determine the optimal model for investigating the water diffusion properties and characterization of rectal carcinoma. Fifty-nine consecutive patients with pathologically confirmed rectal adenocarcinoma underwent DWI with 16 b-values at a 3.0 T MRI system. DWI signals were fitted to the mono-exponential and non-Gaussian diffusion models (IVIM-mono, IVIM-bi and SEM) on primary tumor and adjacent normal rectal tissue. Parameters of standard apparent diffusion coefficient (ADC), slow- and fast-ADC, fraction of fast ADC (f), α value and distributed diffusion coefficient (DDC) were generated and compared between the tumor and normal tissues. The SEM exhibited the best fitting results of actual DWI signal in rectal cancer and the normal rectal wall (R 2 = 0.998, 0.999 respectively). The DDC achieved relatively high area under the curve (AUC = 0.980) in differentiating tumor from normal rectal wall. Non-Gaussian diffusion models could assess tissue properties more accurately than the ADC derived Gaussian diffusion model. SEM may be used as a potential optimal model for characterization of rectal cancer.
Observation of local fields in ZnO using the 111Cd probe
International Nuclear Information System (INIS)
Sato, W.; Komatsuda, S.; Imagawa, E.; Ohkubo, Y.; Yamada, Y.
2011-01-01
The authors prepared the ZnO sample ( 111m Cd-CZO) that contains totally 0.5 at.% of Cd including 111m Cd, and the ZnO sample ( 111m Cd-ICZO) made by doping with 0.5 at.% of In to 111m Cd-CZO, and measured γ-ray perturbed angular correlation (PAC) spectra. They compared these measurement results with the PAC spectra that were observed in the sample ( 111 In-IZO) made by doping with 0.5 at.% of stable In isotope in addition to ( 111 In→) 111 Cd probe, and examined the two characteristics of 111 In-IZO. As for 111 In-IZO, large electric field gradient and late effect due to remarkable EC decay was observed compared with the sample ( 111 In-UZO), where several ppt level of ( 111 In→) 111 Cd probe was solely doped into ZnO. This fact suggests that In atoms and 111 In atoms flocculate locally. When this flocculating condition is made of many In atom groups, several occupation positions of 111 In can be considered, and they cannot form the single frequency component as obtained in the PAC spectra. Therefore, the results of this experiment can be understood that In atoms themselves form the pairs in the nearest position while replacing the lattice positions of Zn. In is generally stable under the condition of three valence, but it can take one valence depending on compounds. Therefore, it can be considered that if In 3+ and In + mixture in this ratio replace Zn 2+ sites, this pairs can exist from the viewpoint of charge balance. (A.O.)
Ilić, Nataša; Pilarczyk, Götz; Lee, Jin-Ho; Logeswaran, Abiramy; Borroni, Aurora Paola; Krufczik, Matthias; Theda, Franziska; Waltrich, Nadine; Bestvater, Felix; Hildenbrand, Georg; Cremer, Christoph; Blank, Michael
2017-01-01
Understanding molecular interactions and regulatory mechanisms in tumor initiation, progression, and treatment response are key requirements towards advanced cancer diagnosis and novel treatment procedures in personalized medicine. Beyond decoding the gene expression, malfunctioning and cancer-related epigenetic pathways, investigations of the spatial receptor arrangements in membranes and genome organization in cell nuclei, on the nano-scale, contribute to elucidating complex molecular mechanisms in cells and tissues. By these means, the correlation between cell function and spatial organization of molecules or molecular complexes can be studied, with respect to carcinogenesis, tumor sensitivity or tumor resistance to anticancer therapies, like radiation or antibody treatment. Here, we present several new applications for bio-molecular nano-probes and super-resolution, laser fluorescence localization microscopy and their potential in life sciences, especially in biomedical and cancer research. By means of a tool-box of fluorescent antibodies, green fluorescent protein (GFP) tagging, or specific oligonucleotides, we present tumor relevant re-arrangements of Erb-receptors in membranes, spatial organization of Smad specific ubiquitin protein ligase 2 (Smurf2) in the cytosol, tumor cell characteristic heterochromatin organization, and molecular re-arrangements induced by radiation or antibody treatment. The main purpose of this article is to demonstrate how nano-scaled distance measurements between bio-molecules, tagged by appropriate nano-probes, can be applied to elucidate structures and conformations of molecular complexes which are characteristic of tumorigenesis and treatment responses. These applications open new avenues towards a better interpretation of the spatial organization and treatment responses of functionally relevant molecules, at the single cell level, in normal and cancer cells, offering new potentials for individualized medicine. PMID:28956810
Directory of Open Access Journals (Sweden)
Michael Hausmann
2017-09-01
Full Text Available Understanding molecular interactions and regulatory mechanisms in tumor initiation, progression, and treatment response are key requirements towards advanced cancer diagnosis and novel treatment procedures in personalized medicine. Beyond decoding the gene expression, malfunctioning and cancer-related epigenetic pathways, investigations of the spatial receptor arrangements in membranes and genome organization in cell nuclei, on the nano-scale, contribute to elucidating complex molecular mechanisms in cells and tissues. By these means, the correlation between cell function and spatial organization of molecules or molecular complexes can be studied, with respect to carcinogenesis, tumor sensitivity or tumor resistance to anticancer therapies, like radiation or antibody treatment. Here, we present several new applications for bio-molecular nano-probes and super-resolution, laser fluorescence localization microscopy and their potential in life sciences, especially in biomedical and cancer research. By means of a tool-box of fluorescent antibodies, green fluorescent protein (GFP tagging, or specific oligonucleotides, we present tumor relevant re-arrangements of Erb-receptors in membranes, spatial organization of Smad specific ubiquitin protein ligase 2 (Smurf2 in the cytosol, tumor cell characteristic heterochromatin organization, and molecular re-arrangements induced by radiation or antibody treatment. The main purpose of this article is to demonstrate how nano-scaled distance measurements between bio-molecules, tagged by appropriate nano-probes, can be applied to elucidate structures and conformations of molecular complexes which are characteristic of tumorigenesis and treatment responses. These applications open new avenues towards a better interpretation of the spatial organization and treatment responses of functionally relevant molecules, at the single cell level, in normal and cancer cells, offering new potentials for individualized medicine.
Energy Technology Data Exchange (ETDEWEB)
Heusch, Philipp [Univ Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, D-40225 Dusseldorf (Germany); Univ Duisburg-Essen, Medical Faculty, Department of Diagnostic and Interventional Radiology and Neuroradiology, D-45147 Essen (Germany); Köhler, Jens [Univ Duisburg-Essen, Medical Faculty, Department of Medical Oncology, D-45147 Essen (Germany); Wittsack, Hans-Joerg [Univ Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, D-40225 Dusseldorf (Germany); Heusner, Till A., E-mail: Heusner@med.uni-duesseldorf.de [Univ Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, D-40225 Dusseldorf (Germany); Buchbender, Christian [Univ Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, D-40225 Dusseldorf (Germany); Poeppel, Thorsten D. [Univ Duisburg-Essen, Medical Faculty, Department of Nuclear Medicine, D-45147 Essen (Germany); Nensa, Felix; Wetter, Axel [Univ Duisburg-Essen, Medical Faculty, Department of Diagnostic and Interventional Radiology and Neuroradiology, D-45147 Essen (Germany); Gauler, Thomas [Univ Duisburg-Essen, Medical Faculty, Department of Medical Oncology, D-45147 Essen (Germany); Hartung, Verena [Univ Duisburg-Essen, Medical Faculty, Department of Nuclear Medicine, D-45147 Essen (Germany); Lanzman, Rotem S. [Univ Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, D-40225 Dusseldorf (Germany)
2013-11-01
Purpose: To assess the feasibility of non-Gaussian DWI as part of a FDG-PET/MRI protocol in patients with histologically proven non-small cell lung cancer. Material and methods: 15 consecutive patients with histologically proven NSCLC (mean age 61 ± 11 years) were included in this study and underwent whole-body FDG-PET/MRI following whole-body FDG-PET/CT. As part of the whole-body FDG-PET/MRI protocol, an EPI-sequence with 5 b-values (0, 100, 500, 1000 and 2000 s/mm{sup 2}) was acquired for DWI of the thorax during free-breathing. Volume of interest (VOI) measurements were performed to determine the maximum and mean standardized uptake value (SUV{sub max}; SUV{sub mean}). A region of interest (ROI) was manually drawn around the tumor on b = 0 images and then transferred to the corresponding parameter maps to assess ADC{sub mono}, D{sub app} and K{sub app}. To assess the goodness of the mathematical fit R{sup 2} was calculated for monoexponential and non-Gaussian analysis. Spearman's correlation coefficients were calculated to compare SUV values and diffusion coefficients. A Student's t-test was performed to compare the monoexponential and non-Gaussian diffusion fitting (R{sup 2}). Results: T staging was equal between FDG-PET/CT and FDG-PET/MRI in 12 of 15 patients. For NSCLC, mean ADC{sub mono} was 2.11 ± 1.24 × 10{sup −3} mm{sup 2}/s, D{sub app} was 2.46 ± 1.29 × 10{sup −3} mm{sup 2}/s and mean K{sub app} was 0.70 ± 0.21. The non-Gaussian diffusion analysis (R{sup 2} = 0.98) provided a significantly better mathematical fitting to the DWI signal decay than the monoexponetial analysis (R{sup 2} = 0.96) (p < 0.001). SUV{sub max} and SUV{sub mean} of NSCLC was 13.5 ± 7.6 and 7.9 ± 4.3 for FDG-PET/MRI. ADC{sub mono} as well as D{sub app} exhibited a significant inverse correlation with the SUV{sub max} (ADC{sub mono}: R = −0.67; p < 0.01; D{sub app}: R = −0.69; p < 0.01) as well as with SUV{sub mean} assessed by FDG-PET/MRI (ADC{sub mono}: R
Cors, J. F.; Lovchik, R. D.; Delamarche, E.; Kaigala, G. V.
2014-03-01
The microfluidic probe (MFP) is a non-contact, scanning microfluidic technology for local (bio)chemical processing of surfaces based on hydrodynamically confining nanoliter volumes of liquids over tens of micrometers. We present here a compact MFP (cMFP) that can be used on a standard inverted microscope and assist in the local processing of tissue sections and biological specimens. The cMFP has a footprint of 175 × 100 × 140 mm3 and can scan an area of 45 × 45 mm2 on a surface with an accuracy of ±15 μm. The cMFP is compatible with standard surfaces used in life science laboratories such as microscope slides and Petri dishes. For ease of use, we developed self-aligned mounted MFP heads with standardized "chip-to-world" and "chip-to-platform" interfaces. Switching the processing liquid in the flow confinement is performed within 90 s using a selector valve with a dead-volume of approximately 5 μl. We further implemented height-compensation that allows a cMFP head to follow non-planar surfaces common in tissue and cellular ensembles. This was shown by patterning different macroscopic copper-coated topographies with height differences up to 750 μm. To illustrate the applicability to tissue processing, 5 μm thick M000921 BRAF V600E+ melanoma cell blocks were stained with hematoxylin to create contours, lines, spots, gradients of the chemicals, and multiple spots over larger areas. The local staining was performed in an interactive manner using a joystick and a scripting module. The compactness, user-friendliness, and functionality of the cMFP will enable it to be adapted as a standard tool in research, development and diagnostic laboratories, particularly for the interaction with tissues and cells.
Mannens, M.; Slater, R. M.; Heyting, C.; Geurts van Kessel, A.; Goedde-Salz, E.; Frants, R. R.; van Ommen, G. J.; Pearson, P. L.
1987-01-01
We are interested in the precise localization of various DNA probes on the short arm of chromosome 11 for our research on the aniridia-Wilms' tumor association (AWTA), assigned to region 11p13 (Knudson and Strong 1972; Riccardi et al. 1978). For this purpose we have screened lymphocyte DNA and
Directional Histogram Ratio at Random Probes: A Local Thresholding Criterion for Capillary Images
Lu, Na; Silva, Jharon; Gu, Yu; Gerber, Scott; Wu, Hulin; Gelbard, Harris; Dewhurst, Stephen; Miao, Hongyu
2013-01-01
With the development of micron-scale imaging techniques, capillaries can be conveniently visualized using methods such as two-photon and whole mount microscopy. However, the presence of background staining, leaky vessels and the diffusion of small fluorescent molecules can lead to significant complexity in image analysis and loss of information necessary to accurately quantify vascular metrics. One solution to this problem is the development of accurate thresholding algorithms that reliably distinguish blood vessels from surrounding tissue. Although various thresholding algorithms have been proposed, our results suggest that without appropriate pre- or post-processing, the existing approaches may fail to obtain satisfactory results for capillary images that include areas of contamination. In this study, we propose a novel local thresholding algorithm, called directional histogram ratio at random probes (DHR-RP). This method explicitly considers the geometric features of tube-like objects in conducting image binarization, and has a reliable performance in distinguishing small vessels from either clean or contaminated background. Experimental and simulation studies suggest that our DHR-RP algorithm is superior over existing thresholding methods. PMID:23525856
Wu, L Y; Wang, K L; Jiang, T; Kang, L; Yang, S Z; Wu, P H
2002-01-01
In this paper, we present our approach to probe the local microwave properties of superconducting thin films by using the microwave near-field scanning technique. We have employed a coaxial cavity together with a niobium tip as the probe and established a scanning sample stage cooled by liquid nitrogen to study thin film devices at low temperature in our scanning microwave near-field microscope. Nondestructive images have been obtained on the inhomogeneity of the YBaCuO superconducting thin films at microwave frequency. We believe that these results would be helpful in evaluating the microwave performance of the devices.
Robert, Damien; Fayol, Delphine; Le Visage, Catherine; Frasca, Guillaume; Brulé, Séverine; Ménager, Christine; Gazeau, Florence; Letourneur, Didier; Wilhelm, Claire
2010-03-01
The in vitro generation of engineered tissue constructs involves the seeding of cells into porous scaffolds. Ongoing challenges are to design scaffolds to meet biochemical and mechanical requirements and to optimize cell seeding in the constructs. In this context, we have developed a simple method based on a magnetic tweezer set-up to manipulate, probe, and position magnetic objects inside a porous scaffold. The magnetic force acting on magnetic objects of various sizes serves as a control parameter to retrieve the local viscosity of the scaffolds internal channels as well as the stiffness of the scaffolds pores. Labeling of human stem cells with iron oxide magnetic nanoparticles makes it possible to perform the same type of measurement with cells as probes and evaluate their own microenvironment. For 18 microm diameter magnetic beads or magnetically labeled stem cells of similar diameter, the viscosity was equivalently equal to 20 mPa s in average. This apparent viscosity was then found to increase with the magnetic probes sizes. The stiffness probed with 100 microm magnetic beads was found in the 50 Pa range, and was lowered by a factor 5 when probed with cells aggregates. The magnetic forces were also successfully applied to the stem cells to enhance the cell seeding process and impose a well defined spatial organization into the scaffold. (c) 2009 Elsevier Ltd. All rights reserved.
Lanzafame, S; Giannelli, M; Garaci, F; Floris, R; Duggento, A; Guerrisi, M; Toschi, N
2016-05-01
/RK/AK values, indicating substantial anatomical variability of these discrepancies. In the HCP dataset, the median voxelwise percentage differences across the whole white matter skeleton were (nonlinear least squares algorithm) 14.5% (8.2%-23.1%) for MD, 4.3% (1.4%-17.3%) for FA, -5.2% (-48.7% to -0.8%) for MO, 12.5% (6.4%-21.2%) for RD, and 16.1% (9.9%-25.6%) for AD (all ranges computed as 0.01 and 0.99 quantiles). All differences/trends were consistent between the discovery (HCP) and replication (local) datasets and between estimation algorithms. However, the relationships between such trends, estimated diffusion tensor invariants, and kurtosis estimates were impacted by the choice of fitting routine. Model-dependent differences in the estimation of conventional indexes of MD/FA/MO/RD/AD can be well beyond commonly seen disease-related alterations. While estimating diffusion tensor-derived indexes using the DKI model may be advantageous in terms of mitigating b-value dependence of diffusivity estimates, such estimates should not be referred to as conventional DTI-derived indexes in order to avoid confusion in interpretation as well as multicenter comparisons. In order to assess the potential and advantages of DKI with respect to DTI as well as to standardize diffusion-weighted imaging methods between centers, both conventional DTI-derived indexes and diffusion tensor invariants derived by fitting the non-Gaussian DKI model should be separately estimated and analyzed using the same combination of fitting routines.
Energy Technology Data Exchange (ETDEWEB)
Wada, Tomoya; Yamazaki, Kenji; Isono, Toshinari; Ogino, Toshio, E-mail: ogino-toshio-rx@ynu.ac.jp
2017-02-28
Highlights: • Local hydrophobicity of phase-separated sapphire (0001) surfaces was investigated. • These surfaces are featured by coexistence of hydrophilic and hydrophobic domains. • Each domain was characterized by colloidal probe atomic force microscopy in water. • Both domains can be distinguished by adhesive forces of the probe to the surfaces. • Characterization in aqueous environment is important in bio-applications of sapphire. - Abstract: Sapphire (0001) surfaces exhibit a phase-separation into hydrophobic and hydrophilic domains upon high-temperature annealing, which were previously distinguished by the thickness of adsorbed water layers in air using atomic force microscopy (AFM). To characterize their local surface hydrophobicity in aqueous environment, we used AFM equipped with a colloidal probe and measured the local adhesive force between each sapphire domain and a hydrophilic SiO{sub 2} probe surface, or a hydrophobic polystyrene one. Two data acquisition modes for statistical analyses were used: one is force measurements at different positions of the surface and the other repeated measurement at a fixed position. We found that adhesive force measurements using the polystyrene probe allow us to distinctly separate the hydrophilic and hydrophobic domains. The dispersion in the force measurement data at different positions of the surface is larger than that in the repeated measurements at a fixed position. It indicates that the adhesive force measurement is repeatable although their data dispersion for the measurement positions is relatively large. From these results, we can conclude that the hydrophilic and hydrophobic domains on the sapphire (0001) surfaces are distinguished by a difference in their hydration degrees.
Zhu, Hao; Fan, Jiangli; Mu, Huiying; Zhu, Tao; Zhang, Zhen; Du, Jianjun; Peng, Xiaojun
2016-10-01
Polarity-sensitive fluorescent probes are powerful chemical tools for studying biomolecular structures and activities both in vitro and in vivo. However, the lack of “off-on” polarity-sensing probes has limited the accurate monitoring of biological processes that involve an increase in local hydrophilicity. Here, we design and synthesize a series of “off-on” polarity-sensitive fluorescent probes BP series consisting of the difluoroboron dippyomethene (BODIPY) fluorophore connected to a quaternary ammonium moiety via different carbon linkers. All these probes showed low fluorescence quantum yields in nonpolar solution but became highly fluorescent in polar media. BP-2, which contains a two-carbon linker and a trimethyl quaternary ammonium, displayed a fluorescence intensity and quantum yield that were both linearly correlated with solvent polarity. In addition, BP-2 exhibited high sensitivity and selectivity for polarity over other environmental factors and a variety of biologically relevant species. BP-2 can be synthesized readily via an unusual Mannich reaction followed by methylation. Using electrochemistry combined with theoretical calculations, we demonstrated that the “off-on” sensing behavior of BP-2 is primarily due to the polarity-dependent donor-excited photoinduced electron transfer (d-PET) effect. Live-cell imaging established that BP-2 enables the detection of local hydrophilicity within lysosomes under conditions of lysosomal dysfunction.
International Nuclear Information System (INIS)
Li Dongxi; Xu Wei; Guo Yongfeng; Li Gaojie
2008-01-01
The mean first-passage time of a bistable system with time-delayed feedback driven by multiplicative non-Gaussian noise and additive Gaussian white noise is investigated. Firstly, the non-Markov process is reduced to the Markov process through a path-integral approach; Secondly, the approximate Fokker-Planck equation is obtained by applying the unified coloured noise approximation, the small time delay approximation and the Novikov Theorem. The functional analysis and simplification are employed to obtain the approximate expressions of MFPT. The effects of non-Gaussian parameter (measures deviation from Gaussian character) r, the delay time τ, the noise correlation time τ 0 , the intensities D and α of noise on the MFPT are discussed. It is found that the escape time could be reduced by increasing the delay time τ, the noise correlation time τ 0 , or by reducing the intensities D and α. As far as we know, this is the first time to consider the effect of delay time on the mean first-passage time in the stochastic dynamical system
Miranda, Rodrigo A.; Schelin, Adriane B.; Chian, Abraham C.-L.; Ferreira, José L.
2018-03-01
In a recent paper (Chian et al., 2016) it was shown that magnetic reconnection at the interface region between two magnetic flux ropes is responsible for the genesis of interplanetary intermittent turbulence. The normalized third-order moment (skewness) and the normalized fourth-order moment (kurtosis) display a quadratic relation with a parabolic shape that is commonly observed in observational data from turbulence in fluids and plasmas, and is linked to non-Gaussian fluctuations due to coherent structures. In this paper we perform a detailed study of the relation between the skewness and the kurtosis of the modulus of the magnetic field |B| during a triple interplanetary magnetic flux rope event. In addition, we investigate the skewness-kurtosis relation of two-point differences of |B| for the same event. The parabolic relation displays scale dependence and is found to be enhanced during magnetic reconnection, rendering support for the generation of non-Gaussian coherent structures via rope-rope magnetic reconnection. Our results also indicate that a direct coupling between the scales of magnetic flux ropes and the scales within the inertial subrange occurs in the solar wind.
A new method for intraoperative localization of epilepsy focus by means of a gamma probe
International Nuclear Information System (INIS)
Carneiro Filho, Omar; Vilela Filho, Osvaldo; Ragazzo, Paulo Cesar; Fonseca, Lea Mirian Barbosa da
2014-01-01
Objective: to evaluate the utility of a new multimodal image-guided intervention technique to detect epileptogenic areas with a gamma probe as compared with intraoperative electrocorticography. Materials and methods: two symptomatic patients with refractory epilepsy underwent magnetic resonance imaging, videoelectroencephalography, brain SPECT scan, neuropsychological evaluation and were submitted to gamma probe-assisted surgery. Results: in patient 1, maximum radioactive count was initially observed on the temporal gyrus at about 3.5 cm posteriorly to the tip of the left temporal lobe. After corticotomy, the gamma probe indicated maximum count at the head of the hippocampus, in agreement with the findings of intraoperative electrocorticography. In patient 2, maximum count was observed in the occipital region at the transition between the temporal and parietal lobes (right hemisphere). During the surgery, the area of epileptogenic activity mapped at electrocorticography was also delimited, demarcated, and compared with the gamma probe findings. After lesionectomy, new radioactive counts were performed both in the patients and on the surgical specimens (ex-vivo). Conclusion: the comparison between intraoperative electrocorticography and gamma probe-assisted surgery showed similarity of both methods. The advantages of gamma probe include: noninvasiveness, low cost and capacity to demonstrate decrease in the radioactive activity at the site of excision after lesionectomy. (author)
Extended x-ray absorption fine structure (EXAFS): a novel probe for local structure of glassy solids
International Nuclear Information System (INIS)
Wong, J.
1979-01-01
The extended x-ray absorption fine structure (EXAFS) is the oscillation in the absorption coefficient extending a few hundred eVs on the high energy side of an x-ray absorption edge. This mode of spectroscopy has recently been realized to be a powerful tool in probing the local atomic structure of all states of matter, particularly with the advent of intense synchrotron radiation. More importantly is the unique ability of EXAFS to probe the structure and dynamics around individual atomic species in a multi-atomic system. In this paper, the physical processes associated with the EXAFS phenomenon will be discussed. Experimental results obtained at the Stanford Synchrotron Radiation Laboratory on some oxide and metallic glasses will be presented. The local structure in these materials are elucidated using a Fourier transform technique
Iima, Mami; Kataoka, Masako; Kanao, Shotaro; Onishi, Natsuko; Kawai, Makiko; Ohashi, Akane; Sakaguchi, Rena; Toi, Masakazu; Togashi, Kaori
2018-05-01
Purpose To investigate the performance of integrated approaches that combined intravoxel incoherent motion (IVIM) and non-Gaussian diffusion parameters compared with the Breast Imaging and Reporting Data System (BI-RADS) to establish multiparameter thresholds scores or probabilities by using Bayesian analysis to distinguish malignant from benign breast lesions and their correlation with molecular prognostic factors. Materials and Methods Between May 2013 and March 2015, 411 patients were prospectively enrolled and 199 patients (allocated to training [n = 99] and validation [n = 100] sets) were included in this study. IVIM parameters (flowing blood volume fraction [fIVIM] and pseudodiffusion coefficient [D*]) and non-Gaussian diffusion parameters (theoretical apparent diffusion coefficient [ADC] at b value of 0 sec/mm 2 [ADC 0 ] and kurtosis [K]) by using IVIM and kurtosis models were estimated from diffusion-weighted image series (16 b values up to 2500 sec/mm 2 ), as well as a synthetic ADC (sADC) calculated by using b values of 200 and 1500 (sADC 200-1500 ) and a standard ADC calculated by using b values of 0 and 800 sec/mm 2 (ADC 0-800 ). The performance of two diagnostic approaches (combined parameter thresholds and Bayesian analysis) combining IVIM and diffusion parameters was evaluated and compared with BI-RADS performance. The Mann-Whitney U test and a nonparametric multiple comparison test were used to compare their performance to determine benignity or malignancy and as molecular prognostic biomarkers and subtypes of breast cancer. Results Significant differences were found between malignant and benign breast lesions for IVIM and non-Gaussian diffusion parameters (ADC 0 , K, fIVIM, fIVIM · D*, sADC 200-1500, and ADC 0-800 ; P < .05). Sensitivity and specificity for the validation set by radiologists A and B were as follows: sensitivity, 94.7% and 89.5%, and specificity, 75.0% and 79.2% for sADC 200-1500 , respectively; sensitivity, 94.7% and 96.1%, and
International Nuclear Information System (INIS)
Rolles, Daniel; Braune, Markus; Cvejanovic, Slobodan; Gessner, Oliver; Hentges, Rainer; Korica, Sanja; Langer, Burkhard; Lischke, Toralf; Pruemper, Georg; Reinkoester, Axel; Viefhaus, Jens; Zimmermann, Bjoern; McKoy, Vince; Becker, Uwe
2006-01-01
In homonuclear diatomic molecules such as N 2 , the inversion symmetry of the system causes non-local, coherent behavior of the otherwise localized core holes. The non-locality of the electron emission and the remaining core hole changes in a continuous way into partially localized behaviour if a gradual breakdown of the inversion symmetry is induced by isotope substitution. This is reflected by a loss of interference and a parity mixing of the outgoing photoelectron waves. Our results represent the first experimentally observed isotope effect on the electronic structure of a diatomic molecule
Flexible probe for measuring local conductivity variations in Li-ion electrode films
Hardy, Emilee; Clement, Derek; Vogel, John; Wheeler, Dean; Mazzeo, Brian
2018-04-01
Li-ion battery performance is governed by electronic and ionic properties of the battery. A key metric that characterizes Li-ion battery cell performance is the electronic conductivity of the electrodes, which are metal foils with thin coatings of electrochemically active materials. To accurately measure the spatial variation of electronic conductivity of these electrodes, a micro-four-line probe (μ4LP) was designed and used to non-destructively measure the properties of commercial-quality Li-ion battery films. This previous research established that the electronic conductivity of film electrodes is not homogeneous throughout the entirety of the deposited film area. In this work, a micro-N-line probe (μNLP) and a flexible micro-flex-line probe (μFLP) were developed to improve the non-destructive micro-scale conductivity measurements that we can take. These devices were validated by comparing test results to that of the predecessor, the micro-four-line probe (μ4LP), on various commercial-quality Li-ion battery electrodes. Results show that there is significant variation in conductivity on a millimeter and even micrometer length scale through the electrode film. Compared to the μ4LP, the μNLP and μFLP also introduce additional measurement configuration possibilities, while providing a more robust design. Researchers and manufacturers can use these probes to identify heterogeneity in their electrodes during the fabrication process, which will lead to the development of better batteries.
Two-phase flow measurements with advanced instrumented spool pieces and local conductivity probes
International Nuclear Information System (INIS)
Turnage, K.G.; Davis, C.E.
1979-01-01
A series of two-phase, air-water and steam-water tests performed with instrumented spool pieces and with conductivity probes obtained from Atomic Energy of Canada, Ltd. is described. The behavior of the three-beam densitometer, turbine meter, and drag flowmeter is discussed in terms of two-phase models. Application of some two-phase mass flow models to the recorded spool piece data is made and preliminary results are shown. Velocity and void fraction information derived from the conductivity probes is presented and compared to velocities and void fractions obtained using the spool piece instrumentation
Trottmann, Matthias; Stepp, Herbert; Sroka, Ronald; Heide, Michael; Liedl, Bernhard; Reese, Sven; Becker, Armin J; Stief, Christian G; Kölle, Sabine
2015-05-01
In azoospermic patients, spermatozoa are routinely obtained by testicular sperm extraction (TESE). However, success rates of this technique are moderate, because the site of excision of testicular tissue is determined arbitrarily. Therefore the aim of this study was to establish probe-based laser endomicroscopy (pCLE) a noval biomedical imaging technique, which provides the opportunity of non-invasive, real-time visualisation of tissue at histological resolution. Using pCLE we clearly visualized longitudinal and horizontal views of the tubuli seminiferi contorti and localized vital spermatozoa. Obtained images and real-time videos were subsequently compared with confocal laser scanning microscopy (CLSM) of spermatozoa and tissues, respectively. Comparative visualization of single native Confocal laser scanning microscopy (CLSM, left) and probe-based laser endomicroscopy (pCLE, right) using Pro Flex(TM) UltraMini O after staining with acriflavine. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Sokolov, R. I.; Abdullin, R. R.
2017-11-01
The use of nonlinear Markov process filtering makes it possible to restore both video stream frames and static photos at the stage of preprocessing. The present paper reflects the results of research in comparison of these types image filtering quality by means of special algorithm when Gaussian or non-Gaussian noises acting. Examples of filter operation at different values of signal-to-noise ratio are presented. A comparative analysis has been performed, and the best filtered kind of noise has been defined. It has been shown the quality of developed algorithm is much better than quality of adaptive one for RGB signal filtering at the same a priori information about the signal. Also, an advantage over median filter takes a place when both fluctuation and pulse noise filtering.
Sirunyan, Albert M; CMS Collaboration; Adam, Wolfgang; Ambrogi, Federico; Asilar, Ece; Bergauer, Thomas; Brandstetter, Johannes; Brondolin, Erica; Dragicevic, Marko; Erö, Janos; Flechl, Martin; Friedl, Markus; Fruehwirth, Rudolf; Ghete, Vasile Mihai; Grossmann, Johannes; Hrubec, Josef; Jeitler, Manfred; König, Axel; Krammer, Natascha; Krätschmer, Ilse; Liko, Dietrich; Madlener, Thomas; Mikulec, Ivan; Pree, Elias; Rad, Navid; Rohringer, Herbert; Schieck, Jochen; Schöfbeck, Robert; Spanring, Markus; Spitzbart, Daniel; Waltenberger, Wolfgang; Wittmann, Johannes; Wulz, Claudia-Elisabeth; Zarucki, Mateusz; Chekhovsky, Vladimir; Mossolov, Vladimir; Suarez Gonzalez, Juan; De Wolf, Eddi A; Di Croce, Davide; Janssen, Xavier; Lauwers, Jasper; Van De Klundert, Merijn; Van Haevermaet, Hans; Van Mechelen, Pierre; Van Remortel, Nick; Abu Zeid, Shimaa; Blekman, Freya; D'Hondt, Jorgen; De Bruyn, Isabelle; De Clercq, Jarne; Deroover, Kevin; Flouris, Giannis; Lontkovskyi, Denys; Lowette, Steven; Marchesini, Ivan; Moortgat, Seth; Moreels, Lieselotte; Python, Quentin; Skovpen, Kirill; Tavernier, Stefaan; Van Doninck, Walter; Van Mulders, Petra; Van Parijs, Isis; Beghin, Diego; Brun, Hugues; Clerbaux, Barbara; De Lentdecker, Gilles; Delannoy, Hugo; Dorney, Brian; Fasanella, Giuseppe; Favart, Laurent; Goldouzian, Reza; Grebenyuk, Anastasia; Lenzi, Thomas; Luetic, Jelena; Maerschalk, Thierry; Marinov, Andrey; Seva, Tomislav; Starling, Elizabeth; Vander Velde, Catherine; Vanlaer, Pascal; Vannerom, David; Yonamine, Ryo; Zenoni, Florian; Zhang, Fengwangdong; Cimmino, Anna; Cornelis, Tom; Dobur, Didar; Fagot, Alexis; Gul, Muhammad; Khvastunov, Illia; Poyraz, Deniz; Roskas, Christos; Salva Diblen, Sinem; Tytgat, Michael; Verbeke, Willem; Zaganidis, Nicolas; Bakhshiansohi, Hamed; Bondu, Olivier; Brochet, Sébastien; Bruno, Giacomo; Caputo, Claudio; Caudron, Adrien; David, Pieter; De Visscher, Simon; Delaere, Christophe; Delcourt, Martin; Francois, Brieuc; Giammanco, Andrea; Komm, Matthias; Krintiras, Georgios; Lemaitre, Vincent; Magitteri, Alessio; Mertens, Alexandre; Musich, Marco; Piotrzkowski, Krzysztof; Quertenmont, Loic; Saggio, Alessia; Vidal Marono, Miguel; Wertz, Sébastien; Zobec, Joze; Aldá Júnior, Walter Luiz; Alves, Fábio Lúcio; Alves, Gilvan; Brito, Lucas; Correa Martins Junior, Marcos; Hensel, Carsten; Moraes, Arthur; Pol, Maria Elena; Rebello Teles, Patricia; Belchior Batista Das Chagas, Ewerton; Carvalho, Wagner; Chinellato, Jose; Coelho, Eduardo; Melo Da Costa, Eliza; Da Silveira, Gustavo Gil; De Jesus Damiao, Dilson; Fonseca De Souza, Sandro; Huertas Guativa, Lina Milena; Malbouisson, Helena; Melo De Almeida, Miqueias; Mora Herrera, Clemencia; Mundim, Luiz; Nogima, Helio; Sanchez Rosas, Luis Junior; Santoro, Alberto; Sznajder, Andre; Thiel, Mauricio; Tonelli Manganote, Edmilson José; Torres Da Silva De Araujo, Felipe; Vilela Pereira, Antonio; Ahuja, Sudha; Bernardes, Cesar Augusto; Tomei, Thiago; De Moraes Gregores, Eduardo; Mercadante, Pedro G; Novaes, Sergio F; Padula, Sandra; Romero Abad, David; Ruiz Vargas, José Cupertino; Aleksandrov, Aleksandar; Hadjiiska, Roumyana; Iaydjiev, Plamen; Misheva, Milena; Rodozov, Mircho; Shopova, Mariana; Sultanov, Georgi; Dimitrov, Anton; Litov, Leander; Pavlov, Borislav; Petkov, Peicho; Fang, Wenxing; Gao, Xuyang; Yuan, Li; Ahmad, Muhammad; Bian, Jian-Guo; Chen, Guo-Ming; Chen, He-Sheng; Chen, Mingshui; Chen, Ye; Jiang, Chun-Hua; Leggat, Duncan; Liao, Hongbo; Liu, Zhenan; Romeo, Francesco; Shaheen, Sarmad Masood; Spiezia, Aniello; Tao, Junquan; Wang, Chunjie; Wang, Zheng; Yazgan, Efe; Zhang, Huaqiao; Zhang, Sijing; Zhao, Jingzhou; Ban, Yong; Chen, Geng; Li, Jing; Li, Qiang; Liu, Shuai; Mao, Yajun; Qian, Si-Jin; Wang, Dayong; Xu, Zijun; Avila, Carlos; Cabrera, Andrés; Chaparro Sierra, Luisa Fernanda; Florez, Carlos; González Hernández, Carlos Felipe; Ruiz Alvarez, José David; Segura Delgado, Manuel Alejandro; Courbon, Benoit; Godinovic, Nikola; Lelas, Damir; Puljak, Ivica; Ribeiro Cipriano, Pedro M; Sculac, Toni; Antunovic, Zeljko; Kovac, Marko; Brigljevic, Vuko; Ferencek, Dinko; Kadija, Kreso; Mesic, Benjamin; Starodumov, Andrei; Susa, Tatjana; Ather, Mohsan Waseem; Attikis, Alexandros; Mavromanolakis, Georgios; Mousa, Jehad; Nicolaou, Charalambos; Ptochos, Fotios; Razis, Panos A; Rykaczewski, Hans; Finger, Miroslav; Finger Jr, Michael; Carrera Jarrin, Edgar; Abdelalim, Ahmed Ali; Mohammed, Yasser; Salama, Elsayed; Dewanjee, Ram Krishna; Kadastik, Mario; Perrini, Lucia; Raidal, Martti; Tiko, Andres; Veelken, Christian; Eerola, Paula; Kirschenmann, Henning; Pekkanen, Juska; Voutilainen, Mikko; Havukainen, Joona; Heikkilä, Jaana Kristiina; Jarvinen, Terhi; Karimäki, Veikko; Kinnunen, Ritva; Lampén, Tapio; Lassila-Perini, Kati; Laurila, Santeri; Lehti, Sami; Lindén, Tomas; Luukka, Panja-Riina; Siikonen, Hannu; Tuominen, Eija; Tuominiemi, Jorma; Tuuva, Tuure; Besancon, Marc; Couderc, Fabrice; Dejardin, Marc; Denegri, Daniel; Faure, Jean-Louis; Ferri, Federico; Ganjour, Serguei; Ghosh, Saranya; Gras, Philippe; Hamel de Monchenault, Gautier; Jarry, Patrick; Kucher, Inna; Leloup, Clément; Locci, Elizabeth; Machet, Martina; Malcles, Julie; Negro, Giulia; Rander, John; Rosowsky, André; Sahin, Mehmet Özgür; Titov, Maksym; Abdulsalam, Abdulla; Amendola, Chiara; Antropov, Iurii; Baffioni, Stephanie; Beaudette, Florian; Busson, Philippe; Cadamuro, Luca; Charlot, Claude; Granier de Cassagnac, Raphael; Jo, Mihee; Lisniak, Stanislav; Lobanov, Artur; Martin Blanco, Javier; Nguyen, Matthew; Ochando, Christophe; Ortona, Giacomo; Paganini, Pascal; Pigard, Philipp; Salerno, Roberto; Sauvan, Jean-Baptiste; Sirois, Yves; Stahl Leiton, Andre Govinda; Strebler, Thomas; Yilmaz, Yetkin; Zabi, Alexandre; Zghiche, Amina; Agram, Jean-Laurent; Andrea, Jeremy; Bloch, Daniel; Brom, Jean-Marie; Buttignol, Michael; Chabert, Eric Christian; Chanon, Nicolas; Collard, Caroline; Conte, Eric; Coubez, Xavier; Fontaine, Jean-Charles; Gelé, Denis; Goerlach, Ulrich; Jansová, Markéta; Le Bihan, Anne-Catherine; Tonon, Nicolas; Van Hove, Pierre; Gadrat, Sébastien; Beauceron, Stephanie; Bernet, Colin; Boudoul, Gaelle; Chierici, Roberto; Contardo, Didier; Depasse, Pierre; El Mamouni, Houmani; Fay, Jean; Finco, Linda; Gascon, Susan; Gouzevitch, Maxime; Grenier, Gérald; Ille, Bernard; Lagarde, Francois; Laktineh, Imad Baptiste; Lethuillier, Morgan; Mirabito, Laurent; Pequegnot, Anne-Laure; Perries, Stephane; Popov, Andrey; Sordini, Viola; Vander Donckt, Muriel; Viret, Sébastien; Toriashvili, Tengizi; Tsamalaidze, Zviad; Autermann, Christian; Feld, Lutz; Kiesel, Maximilian Knut; Klein, Katja; Lipinski, Martin; Preuten, Marius; Schomakers, Christian; Schulz, Johannes; Zhukov, Valery; Albert, Andreas; Dietz-Laursonn, Erik; Duchardt, Deborah; Endres, Matthias; Erdmann, Martin; Erdweg, Sören; Esch, Thomas; Fischer, Robert; Güth, Andreas; Hamer, Matthias; Hebbeker, Thomas; Heidemann, Carsten; Hoepfner, Kerstin; Knutzen, Simon; Merschmeyer, Markus; Meyer, Arnd; Millet, Philipp; Mukherjee, Swagata; Pook, Tobias; Radziej, Markus; Reithler, Hans; Rieger, Marcel; Scheuch, Florian; Teyssier, Daniel; Thüer, Sebastian; Flügge, Günter; Kargoll, Bastian; Kress, Thomas; Künsken, Andreas; Müller, Thomas; Nehrkorn, Alexander; Nowack, Andreas; Pistone, Claudia; Pooth, Oliver; Stahl, Achim; Aldaya Martin, Maria; Arndt, Till; Asawatangtrakuldee, Chayanit; Beernaert, Kelly; Behnke, Olaf; Behrens, Ulf; Bermúdez Martínez, Armando; Bin Anuar, Afiq Aizuddin; Borras, Kerstin; Botta, Valeria; Campbell, Alan; Connor, Patrick; Contreras-Campana, Christian; Costanza, Francesco; Diez Pardos, Carmen; Eckerlin, Guenter; Eckstein, Doris; Eichhorn, Thomas; Eren, Engin; Gallo, Elisabetta; Garay Garcia, Jasone; Geiser, Achim; Grados Luyando, Juan Manuel; Grohsjean, Alexander; Gunnellini, Paolo; Guthoff, Moritz; Harb, Ali; Hauk, Johannes; Hempel, Maria; Jung, Hannes; Kasemann, Matthias; Keaveney, James; Kleinwort, Claus; Korol, Ievgen; Krücker, Dirk; Lange, Wolfgang; Lelek, Aleksandra; Lenz, Teresa; Leonard, Jessica; Lipka, Katerina; Lohmann, Wolfgang; Mankel, Rainer; Melzer-Pellmann, Isabell-Alissandra; Meyer, Andreas Bernhard; Mittag, Gregor; Mnich, Joachim; Mussgiller, Andreas; Ntomari, Eleni; Pitzl, Daniel; Raspereza, Alexei; Savitskyi, Mykola; Saxena, Pooja; Shevchenko, Rostyslav; Spannagel, Simon; Stefaniuk, Nazar; Van Onsem, Gerrit Patrick; Walsh, Roberval; Wen, Yiwen; Wichmann, Katarzyna; Wissing, Christoph; Zenaiev, Oleksandr; Aggleton, Robin; Bein, Samuel; Blobel, Volker; Centis Vignali, Matteo; Dreyer, Torben; Garutti, Erika; Gonzalez, Daniel; Haller, Johannes; Hinzmann, Andreas; Hoffmann, Malte; Karavdina, Anastasia; Klanner, Robert; Kogler, Roman; Kovalchuk, Nataliia; Kurz, Simon; Lapsien, Tobias; Marconi, Daniele; Meyer, Mareike; Niedziela, Marek; Nowatschin, Dominik; Pantaleo, Felice; Peiffer, Thomas; Perieanu, Adrian; Scharf, Christian; Schleper, Peter; Schmidt, Alexander; Schumann, Svenja; Schwandt, Joern; Sonneveld, Jory; Stadie, Hartmut; Steinbrück, Georg; Stober, Fred-Markus Helmut; Stöver, Marc; Tholen, Heiner; Troendle, Daniel; Usai, Emanuele; Vanhoefer, Annika; Vormwald, Benedikt; Akbiyik, Melike; Barth, Christian; Baselga, Marta; Baur, Sebastian; Butz, Erik; Caspart, René; Chwalek, Thorsten; Colombo, Fabio; De Boer, Wim; Dierlamm, Alexander; Faltermann, Nils; Freund, Benedikt; Friese, Raphael; Giffels, Manuel; Harrendorf, Marco Alexander; Hartmann, Frank; Heindl, Stefan Michael; Husemann, Ulrich; Kassel, Florian; Kudella, Simon; Mildner, Hannes; Mozer, Matthias Ulrich; Müller, Thomas; Plagge, Michael; Quast, Gunter; Rabbertz, Klaus; Schröder, Matthias; Shvetsov, Ivan; Sieber, Georg; Simonis, Hans-Jürgen; Ulrich, Ralf; Wayand, Stefan; Weber, Marc; Weiler, Thomas; Williamson, Shawn; Wöhrmann, Clemens; Wolf, Roger; Anagnostou, Georgios; Daskalakis, Georgios; Geralis, Theodoros; Kyriakis, Aristotelis; Loukas, Demetrios; Topsis-Giotis, Iasonas; Karathanasis, George; Kesisoglou, Stilianos; Panagiotou, Apostolos; Saoulidou, Niki; Kousouris, Konstantinos; Evangelou, Ioannis; Foudas, Costas; Gianneios, Paraskevas; Katsoulis, Panagiotis; Kokkas, Panagiotis; Mallios, Stavros; Manthos, Nikolaos; Papadopoulos, Ioannis; Paradas, Evangelos; Strologas, John; Triantis, Frixos A; Tsitsonis, Dimitrios; Csanad, Mate; Filipovic, Nicolas; Pasztor, Gabriella; Surányi, Olivér; Veres, Gabor Istvan; Bencze, Gyorgy; Hajdu, Csaba; Horvath, Dezso; Hunyadi, Ádám; Sikler, Ferenc; Veszpremi, Viktor; Beni, Noemi; Czellar, Sandor; Karancsi, János; Makovec, Alajos; Molnar, Jozsef; Szillasi, Zoltan; Bartók, Márton; Raics, Peter; Trocsanyi, Zoltan Laszlo; Ujvari, Balazs; Choudhury, Somnath; Komaragiri, Jyothsna Rani; Bahinipati, Seema; Bhowmik, Sandeep; Mal, Prolay; Mandal, Koushik; Nayak, Aruna; Sahoo, Deepak Kumar; Sahoo, Niladribihari; Swain, Sanjay Kumar; Bansal, Sunil; Beri, Suman Bala; Bhatnagar, Vipin; Chawla, Ridhi; Dhingra, Nitish; Kalsi, Amandeep Kaur; Kaur, Anterpreet; Kaur, Manjit; Kaur, Sandeep; Kumar, Ramandeep; Kumari, Priyanka; Mehta, Ankita; Singh, Jasbir; Walia, Genius; Kumar, Ashok; Shah, Aashaq; Bhardwaj, Ashutosh; Chauhan, Sushil; Choudhary, Brajesh C; Garg, Rocky Bala; Keshri, Sumit; Kumar, Ajay; Malhotra, Shivali; Naimuddin, Md; Ranjan, Kirti; Sharma, Ramkrishna; Bhardwaj, Rishika; Bhattacharya, Rajarshi; Bhattacharya, Satyaki; Bhawandeep, Bhawandeep; Dey, Sourav; Dutt, Suneel; Dutta, Suchandra; Ghosh, Shamik; Majumdar, Nayana; Modak, Atanu; Mondal, Kuntal; Mukhopadhyay, Supratik; Nandan, Saswati; Purohit, Arnab; Roy, Ashim; Roy Chowdhury, Suvankar; Sarkar, Subir; Sharan, Manoj; Thakur, Shalini; Behera, Prafulla Kumar; Chudasama, Ruchi; Dutta, Dipanwita; Jha, Vishwajeet; Kumar, Vineet; Mohanty, Ajit Kumar; Netrakanti, Pawan Kumar; Pant, Lalit Mohan; Shukla, Prashant; Topkar, Anita; Aziz, Tariq; Dugad, Shashikant; Mahakud, Bibhuprasad; Mitra, Soureek; Mohanty, Gagan Bihari; Sur, Nairit; Sutar, Bajrang; Banerjee, Sudeshna; Bhattacharya, Soham; Chatterjee, Suman; Das, Pallabi; Guchait, Monoranjan; Jain, Sandhya; Kumar, Sanjeev; Maity, Manas; Majumder, Gobinda; Mazumdar, Kajari; Sarkar, Tanmay; Wickramage, Nadeesha; Chauhan, Shubhanshu; Dube, Sourabh; Hegde, Vinay; Kapoor, Anshul; Kothekar, Kunal; Pandey, Shubham; Rane, Aditee; Sharma, Seema; Chenarani, Shirin; Eskandari Tadavani, Esmaeel; Etesami, Seyed Mohsen; Khakzad, Mohsen; Mohammadi Najafabadi, Mojtaba; Naseri, Mohsen; Paktinat Mehdiabadi, Saeid; Rezaei Hosseinabadi, Ferdos; Safarzadeh, Batool; Zeinali, Maryam; Felcini, Marta; Grunewald, Martin; Abbrescia, Marcello; Calabria, Cesare; Colaleo, Anna; Creanza, Donato; Cristella, Leonardo; De Filippis, Nicola; De Palma, Mauro; Errico, Filippo; Fiore, Luigi; Iaselli, Giuseppe; Lezki, Samet; Maggi, Giorgio; Maggi, Marcello; Miniello, Giorgia; My, Salvatore; Nuzzo, Salvatore; Pompili, Alexis; Pugliese, Gabriella; Radogna, Raffaella; Ranieri, Antonio; Selvaggi, Giovanna; Sharma, Archana; Silvestris, Lucia; Venditti, Rosamaria; Verwilligen, Piet; Abbiendi, Giovanni; Battilana, Carlo; Bonacorsi, Daniele; Borgonovi, Lisa; Braibant-Giacomelli, Sylvie; Campanini, Renato; Capiluppi, Paolo; Castro, Andrea; Cavallo, Francesca Romana; Chhibra, Simranjit Singh; Codispoti, Giuseppe; Cuffiani, Marco; Dallavalle, Gaetano-Marco; Fabbri, Fabrizio; Fanfani, Alessandra; Fasanella, Daniele; Giacomelli, Paolo; Grandi, Claudio; Guiducci, Luigi; Marcellini, Stefano; Masetti, Gianni; Montanari, Alessandro; Navarria, Francesco; Perrotta, Andrea; Rossi, Antonio; Rovelli, Tiziano; Siroli, Gian Piero; Tosi, Nicolò; Albergo, Sebastiano; Costa, Salvatore; Di Mattia, Alessandro; Giordano, Ferdinando; Potenza, Renato; Tricomi, Alessia; Tuve, Cristina; Barbagli, Giuseppe; Chatterjee, Kalyanmoy; Ciulli, Vitaliano; Civinini, Carlo; D'Alessandro, Raffaello; Focardi, Ettore; Lenzi, Piergiulio; Meschini, Marco; Paoletti, Simone; Russo, Lorenzo; Sguazzoni, Giacomo; Strom, Derek; Viliani, Lorenzo; Benussi, Luigi; Bianco, Stefano; Fabbri, Franco; Piccolo, Davide; Primavera, Federica; Calvelli, Valerio; Ferro, Fabrizio; Robutti, Enrico; Tosi, Silvano; Benaglia, Andrea; Beschi, Andrea; Brianza, Luca; Brivio, Francesco; Ciriolo, Vincenzo; Dinardo, Mauro Emanuele; Fiorendi, Sara; Gennai, Simone; Ghezzi, Alessio; Govoni, Pietro; Malberti, Martina; Malvezzi, Sandra; Manzoni, Riccardo Andrea; Menasce, Dario; Moroni, Luigi; Paganoni, Marco; Pauwels, Kristof; Pedrini, Daniele; Pigazzini, Simone; Ragazzi, Stefano; Tabarelli de Fatis, Tommaso; Buontempo, Salvatore; Cavallo, Nicola; Di Guida, Salvatore; Fabozzi, Francesco; Fienga, Francesco; Iorio, Alberto Orso Maria; Khan, Wajid Ali; Lista, Luca; Meola, Sabino; Paolucci, Pierluigi; Sciacca, Crisostomo; Thyssen, Filip; Azzi, Patrizia; Bacchetta, Nicola; Benato, Lisa; Bisello, Dario; Boletti, Alessio; Carlin, Roberto; Carvalho Antunes De Oliveira, Alexandra; Checchia, Paolo; Dall'Osso, Martino; De Castro Manzano, Pablo; Dorigo, Tommaso; Gasparini, Fabrizio; Gasparini, Ugo; Gozzelino, Andrea; Gulmini, Michele; Lacaprara, Stefano; Lujan, Paul; Margoni, Martino; Meneguzzo, Anna Teresa; Pozzobon, Nicola; Ronchese, Paolo; Rossin, Roberto; Torassa, Ezio; Ventura, Sandro; Zanetti, Marco; Zumerle, Gianni; Braghieri, Alessandro; Magnani, Alice; Montagna, Paolo; Ratti, Sergio P; Re, Valerio; Ressegotti, Martina; Riccardi, Cristina; Salvini, Paola; Vai, Ilaria; Vitulo, Paolo; Alunni Solestizi, Luisa; Biasini, Maurizio; Bilei, Gian Mario; Cecchi, Claudia; Ciangottini, Diego; Fanò, Livio; Leonardi, Roberto; Manoni, Elisa; Mantovani, Giancarlo; Mariani, Valentina; Menichelli, Mauro; Rossi, Alessandro; Santocchia, Attilio; Spiga, Daniele; Androsov, Konstantin; Azzurri, Paolo; Bagliesi, Giuseppe; Boccali, Tommaso; Borrello, Laura; Castaldi, Rino; Ciocci, Maria Agnese; Dell'Orso, Roberto; Fedi, Giacomo; Giannini, Leonardo; Giassi, Alessandro; Grippo, Maria Teresa; Ligabue, Franco; Lomtadze, Teimuraz; Manca, Elisabetta; Mandorli, Giulio; Messineo, Alberto; Palla, Fabrizio; Rizzi, Andrea; Savoy-Navarro, Aurore; Spagnolo, Paolo; Tenchini, Roberto; Tonelli, Guido; Venturi, Andrea; Verdini, Piero Giorgio; Barone, Luciano; Cavallari, Francesca; Cipriani, Marco; Daci, Nadir; Del Re, Daniele; Di Marco, Emanuele; Diemoz, Marcella; Gelli, Simone; Longo, Egidio; Margaroli, Fabrizio; Marzocchi, Badder; Meridiani, Paolo; Organtini, Giovanni; Paramatti, Riccardo; Preiato, Federico; Rahatlou, Shahram; Rovelli, Chiara; Santanastasio, Francesco; Amapane, Nicola; Arcidiacono, Roberta; Argiro, Stefano; Arneodo, Michele; Bartosik, Nazar; Bellan, Riccardo; Biino, Cristina; Cartiglia, Nicolo; Cenna, Francesca; Costa, Marco; Covarelli, Roberto; Degano, Alessandro; Demaria, Natale; Kiani, Bilal; Mariotti, Chiara; Maselli, Silvia; Migliore, Ernesto; Monaco, Vincenzo; Monteil, Ennio; Monteno, Marco; Obertino, Maria Margherita; Pacher, Luca; Pastrone, Nadia; Pelliccioni, Mario; Pinna Angioni, Gian Luca; Ravera, Fabio; Romero, Alessandra; Ruspa, Marta; Sacchi, Roberto; Shchelina, Ksenia; Sola, Valentina; Solano, Ada; Staiano, Amedeo; Traczyk, Piotr; Belforte, Stefano; Casarsa, Massimo; Cossutti, Fabio; Della Ricca, Giuseppe; Zanetti, Anna; Kim, Dong Hee; Kim, Gui Nyun; Kim, Min Suk; Lee, Jeongeun; Lee, Sangeun; Lee, Seh Wook; Moon, Chang-Seong; Oh, Young Do; Sekmen, Sezen; Son, Dong-Chul; Yang, Yu Chul; Lee, Ari; Kim, Hyunchul; Moon, Dong Ho; Oh, Geonhee; Brochero Cifuentes, Javier Andres; Goh, Junghwan; Kim, Tae Jeong; Cho, Sungwoong; Choi, Suyong; Go, Yeonju; Gyun, Dooyeon; Ha, Seungkyu; Hong, Byung-Sik; Jo, Youngkwon; Kim, Yongsun; Lee, Kisoo; Lee, Kyong Sei; Lee, Songkyo; Lim, Jaehoon; Park, Sung Keun; Roh, Youn; Almond, John; Kim, Junho; Kim, Jae Sung; Lee, Haneol; Lee, Kyeongpil; Nam, Kyungwook; Oh, Sung Bin; Radburn-Smith, Benjamin Charles; Seo, Seon-hee; Yang, Unki; Yoo, Hwi Dong; Yu, Geum Bong; Kim, Hyunyong; Kim, Ji Hyun; Lee, Jason Sang Hun; Park, Inkyu; Choi, Young-Il; Hwang, Chanwook; Lee, Jongseok; Yu, Intae; Dudenas, Vytautas; Juodagalvis, Andrius; Vaitkus, Juozas; Ahmed, Ijaz; Ibrahim, Zainol Abidin; Md Ali, Mohd Adli Bin; Mohamad Idris, Faridah; Wan Abdullah, Wan Ahmad Tajuddin; Yusli, Mohd Nizam; Zolkapli, Zukhaimira; Reyes-Almanza, Rogelio; Ramirez-Sanchez, Gabriel; Duran-Osuna, Cecilia; Castilla-Valdez, Heriberto; De La Cruz-Burelo, Eduard; Heredia-De La Cruz, Ivan; Rabadán-Trejo, Raúl Iraq; Lopez-Fernandez, Ricardo; Mejia Guisao, Jhovanny; Sánchez Hernández, Alberto; Carrillo Moreno, Salvador; Oropeza Barrera, Cristina; Vazquez Valencia, Fabiola; Eysermans, Jan; Pedraza, Isabel; Salazar Ibarguen, Humberto Antonio; Uribe Estrada, Cecilia; Morelos Pineda, Antonio; Krofcheck, David; Butler, Philip H; Ahmad, Ashfaq; Ahmad, Muhammad; Hassan, Qamar; Hoorani, Hafeez R; Saddique, Asif; Shah, Mehar Ali; Shoaib, Muhammad; Waqas, Muhammad; Bialkowska, Helena; Bluj, Michal; Boimska, Bozena; Frueboes, Tomasz; Górski, Maciej; Kazana, Malgorzata; Nawrocki, Krzysztof; Szleper, Michal; Zalewski, Piotr; Bunkowski, Karol; Byszuk, Adrian; Doroba, Krzysztof; Kalinowski, Artur; Konecki, Marcin; Krolikowski, Jan; Misiura, Maciej; Olszewski, Michal; Pyskir, Andrzej; Walczak, Marek; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Di Francesco, Agostino; Faccioli, Pietro; Galinhas, Bruno; Gallinaro, Michele; Hollar, Jonathan; Leonardo, Nuno; Lloret Iglesias, Lara; Nemallapudi, Mythra Varun; Seixas, Joao; Strong, Giles; Toldaiev, Oleksii; Vadruccio, Daniele; Varela, Joao; Baginyan, Andrey; Golunov, Alexey; Golutvin, Igor; Karjavin, Vladimir; Korenkov, Vladimir; Kozlov, Guennady; Lanev, Alexander; Malakhov, Alexander; Matveev, Viktor; Mitsyn, Valeri Valentinovitch; Palichik, Vladimir; Perelygin, Victor; Shmatov, Sergey; Skatchkov, Nikolai; Smirnov, Vitaly; Yuldashev, Bekhzod S; Zarubin, Anatoli; Zhiltsov, Victor; Ivanov, Yury; Kim, Victor; Kuznetsova, Ekaterina; Levchenko, Petr; Murzin, Victor; Oreshkin, Vadim; Smirnov, Igor; Sosnov, Dmitry; Sulimov, Valentin; Uvarov, Lev; Vavilov, Sergey; Vorobyev, Alexey; Andreev, Yuri; Dermenev, Alexander; Gninenko, Sergei; Golubev, Nikolai; Karneyeu, Anton; Kirsanov, Mikhail; Krasnikov, Nikolai; Pashenkov, Anatoli; Tlisov, Danila; Toropin, Alexander; Epshteyn, Vladimir; Gavrilov, Vladimir; Lychkovskaya, Natalia; Popov, Vladimir; Pozdnyakov, Ivan; Safronov, Grigory; Spiridonov, Alexander; Stepennov, Anton; Toms, Maria; Vlasov, Evgueni; Zhokin, Alexander; Aushev, Tagir; Bylinkin, Alexander; Chistov, Ruslan; Danilov, Mikhail; Parygin, Pavel; Philippov, Dmitry; Polikarpov, Sergey; Tarkovskii, Evgenii; Zhemchugov, Evgenii; Andreev, Vladimir; Azarkin, Maksim; Dremin, Igor; Kirakosyan, Martin; Terkulov, Adel; Baskakov, Alexey; Belyaev, Andrey; Boos, Edouard; Ershov, Alexander; Gribushin, Andrey; Kaminskiy, Alexandre; Kodolova, Olga; Korotkikh, Vladimir; Lokhtin, Igor; Miagkov, Igor; Nazarova, Elizaveta; Obraztsov, Stepan; Petrushanko, Sergey; Savrin, Viktor; Snigirev, Alexander; Vardanyan, Irina; Blinov, Vladimir; Skovpen, Yuri; Shtol, Dmitry; Azhgirey, Igor; Bayshev, Igor; Bitioukov, Sergei; Elumakhov, Dmitry; Godizov, Anton; Kachanov, Vassili; Kalinin, Alexey; Konstantinov, Dmitri; Mandrik, Petr; Petrov, Vladimir; Ryutin, Roman; Sobol, Andrei; Troshin, Sergey; Tyurin, Nikolay; Uzunian, Andrey; Volkov, Alexey; Adzic, Petar; Cirkovic, Predrag; Devetak, Damir; Dordevic, Milos; Milosevic, Jovan; Rekovic, Vladimir; Alcaraz Maestre, Juan; Bachiller, Irene; Barrio Luna, Mar; Cerrada, Marcos; Colino, Nicanor; De La Cruz, Begona; Delgado Peris, Antonio; Escalante Del Valle, Alberto; Fernandez Bedoya, Cristina; Fernández Ramos, Juan Pablo; Flix, Jose; Fouz, Maria Cruz; Gonzalez Lopez, Oscar; Goy Lopez, Silvia; Hernandez, Jose M; Josa, Maria Isabel; Moran, Dermot; Pérez-Calero Yzquierdo, Antonio María; Puerta Pelayo, Jesus; Quintario Olmeda, Adrián; Redondo, Ignacio; Romero, Luciano; Senghi Soares, Mara; Álvarez Fernández, Adrian; Albajar, Carmen; de Trocóniz, Jorge F; Missiroli, Marino; Cuevas, Javier; Erice, Carlos; Fernandez Menendez, Javier; Gonzalez Caballero, Isidro; González Fernández, Juan Rodrigo; Palencia Cortezon, Enrique; Sanchez Cruz, Sergio; Vischia, Pietro; Vizan Garcia, Jesus Manuel; Cabrillo, Iban Jose; Calderon, Alicia; Chazin Quero, Barbara; Curras, Esteban; Duarte Campderros, Jordi; Fernandez, Marcos; Garcia-Ferrero, Juan; Gomez, Gervasio; Lopez Virto, Amparo; Marco, Jesus; Martinez Rivero, Celso; Martinez Ruiz del Arbol, Pablo; Matorras, Francisco; Piedra Gomez, Jonatan; Rodrigo, Teresa; Ruiz-Jimeno, Alberto; Scodellaro, Luca; Trevisani, Nicolò; Vila, Ivan; Vilar Cortabitarte, Rocio; Abbaneo, Duccio; Akgun, Bora; Auffray, Etiennette; Baillon, Paul; Ball, Austin; Barney, David; Bendavid, Joshua; Bianco, Michele; Bloch, Philippe; Bocci, Andrea; Botta, Cristina; Camporesi, Tiziano; Castello, Roberto; Cepeda, Maria; Cerminara, Gianluca; Chapon, Emilien; Chen, Yi; D'Enterria, David; Dabrowski, Anne; Daponte, Vincenzo; David Tinoco Mendes, Andre; De Gruttola, Michele; De Roeck, Albert; Deelen, Nikkie; Dobson, Marc; Du Pree, Tristan; Dünser, Marc; Dupont, Niels; Elliott-Peisert, Anna; Everaerts, Pieter; Fallavollita, Francesco; Franzoni, Giovanni; Fulcher, Jonathan; Funk, Wolfgang; Gigi, Dominique; Gilbert, Andrew; Gill, Karl; Glege, Frank; Gulhan, Doga; Harris, Philip; Hegeman, Jeroen; Innocente, Vincenzo; Jafari, Abideh; Janot, Patrick; Karacheban, Olena; Kieseler, Jan; Knünz, Valentin; Kornmayer, Andreas; Kortelainen, Matti J; Krammer, Manfred; Lange, Clemens; Lecoq, Paul; Lourenco, Carlos; Lucchini, Marco Toliman; Malgeri, Luca; Mannelli, Marcello; Martelli, Arabella; Meijers, Frans; Merlin, Jeremie Alexandre; Mersi, Stefano; Meschi, Emilio; Milenovic, Predrag; Moortgat, Filip; Mulders, Martijn; Neugebauer, Hannes; Ngadiuba, Jennifer; Orfanelli, Styliani; Orsini, Luciano; Pape, Luc; Perez, Emmanuel; Peruzzi, Marco; Petrilli, Achille; Petrucciani, Giovanni; Pfeiffer, Andreas; Pierini, Maurizio; Rabady, Dinyar; Racz, Attila; Reis, Thomas; Rolandi, Gigi; Rovere, Marco; Sakulin, Hannes; Schäfer, Christoph; Schwick, Christoph; Seidel, Markus; Selvaggi, Michele; Sharma, Archana; Silva, Pedro; Sphicas, Paraskevas; Stakia, Anna; Steggemann, Jan; Stoye, Markus; Tosi, Mia; Treille, Daniel; Triossi, Andrea; Tsirou, Andromachi; Veckalns, Viesturs; Verweij, Marta; Zeuner, Wolfram Dietrich; Bertl, Willi; Caminada, Lea; Deiters, Konrad; Erdmann, Wolfram; Horisberger, Roland; Ingram, Quentin; Kaestli, Hans-Christian; Kotlinski, Danek; Langenegger, Urs; Rohe, Tilman; Wiederkehr, Stephan Albert; Backhaus, Malte; Bäni, Lukas; Berger, Pirmin; Bianchini, Lorenzo; Casal, Bruno; Dissertori, Günther; Dittmar, Michael; Donegà, Mauro; Dorfer, Christian; Grab, Christoph; Heidegger, Constantin; Hits, Dmitry; Hoss, Jan; Kasieczka, Gregor; Klijnsma, Thomas; Lustermann, Werner; Mangano, Boris; Marionneau, Matthieu; Meinhard, Maren Tabea; Meister, Daniel; Micheli, Francesco; Musella, Pasquale; Nessi-Tedaldi, Francesca; Pandolfi, Francesco; Pata, Joosep; Pauss, Felicitas; Perrin, Gaël; Perrozzi, Luca; Quittnat, Milena; Reichmann, Michael; Sanz Becerra, Diego Alejandro; Schönenberger, Myriam; Shchutska, Lesya; Tavolaro, Vittorio Raoul; Theofilatos, Konstantinos; Vesterbacka Olsson, Minna Leonora; Wallny, Rainer; Zhu, De Hua; Aarrestad, Thea Klaeboe; Amsler, Claude; Canelli, Maria Florencia; De Cosa, Annapaola; Del Burgo, Riccardo; Donato, Silvio; Galloni, Camilla; Hreus, Tomas; Kilminster, Benjamin; Pinna, Deborah; Rauco, Giorgia; Robmann, Peter; Salerno, Daniel; Schweiger, Korbinian; Seitz, Claudia; Takahashi, Yuta; Zucchetta, Alberto; Candelise, Vieri; Chang, Yu-Hsiang; Cheng, Kai-yu; Doan, Thi Hien; Jain, Shilpi; Khurana, Raman; Kuo, Chia-Ming; Lin, Willis; Pozdnyakov, Andrey; Yu, Shin-Shan; Kumar, Arun; Chang, Paoti; Chao, Yuan; Chen, Kai-Feng; Chen, Po-Hsun; Fiori, Francesco; Hou, George Wei-Shu; Hsiung, Yee; Liu, Yueh-Feng; Lu, Rong-Shyang; Paganis, Efstathios; Psallidas, Andreas; Steen, Arnaud; Tsai, Jui-fa; Asavapibhop, Burin; Kovitanggoon, Kittikul; Singh, Gurpreet; Srimanobhas, Norraphat; Bakirci, Mustafa Numan; Bat, Ayse; Boran, Fatma; Damarseckin, Serdal; Demiroglu, Zuhal Seyma; Dozen, Candan; Eskut, Eda; Girgis, Semiray; Gokbulut, Gul; Guler, Yalcin; Hos, Ilknur; Kangal, Evrim Ersin; Kara, Ozgun; Kayis Topaksu, Aysel; Kiminsu, Ugur; Oglakci, Mehmet; Onengut, Gulsen; Ozdemir, Kadri; Polatoz, Ayse; Tok, Ufuk Guney; Topakli, Huseyin; Turkcapar, Semra; Zorbakir, Ibrahim Soner; Zorbilmez, Caglar; Bilin, Bugra; Karapinar, Guler; Ocalan, Kadir; Yalvac, Metin; Zeyrek, Mehmet; Gülmez, Erhan; Kaya, Mithat; Kaya, Ozlem; Tekten, Sevgi; Yetkin, Elif Asli; Nazlim Agaras, Merve; Atay, Serhat; Cakir, Altan; Cankocak, Kerem; Köseoglu, Ilknur; Grynyov, Boris; Levchuk, Leonid; Ball, Fionn; Beck, Lana; Brooke, James John; Burns, Douglas; Clement, Emyr; Cussans, David; Davignon, Olivier; Flacher, Henning; Goldstein, Joel; Heath, Greg P; Heath, Helen F; Kreczko, Lukasz; Newbold, Dave M; Paramesvaran, Sudarshan; Sakuma, Tai; Seif El Nasr-storey, Sarah; Smith, Dominic; Smith, Vincent J; Belyaev, Alexander; Brew, Christopher; Brown, Robert M; Calligaris, Luigi; Cieri, Davide; Cockerill, David JA; Coughlan, John A; Harder, Kristian; Harper, Sam; Linacre, Jacob; Olaiya, Emmanuel; Petyt, David; Shepherd-Themistocleous, Claire; Thea, Alessandro; Tomalin, Ian R; Williams, Thomas; Auzinger, Georg; Bainbridge, Robert; Borg, Johan; Breeze, Shane; Buchmuller, Oliver; Bundock, Aaron; Casasso, Stefano; Citron, Matthew; Colling, David; Corpe, Louie; Dauncey, Paul; Davies, Gavin; De Wit, Adinda; Della Negra, Michel; Di Maria, Riccardo; Elwood, Adam; Haddad, Yacine; Hall, Geoffrey; Iles, Gregory; James, Thomas; Lane, Rebecca; Laner, Christian; Lyons, Louis; Magnan, Anne-Marie; Malik, Sarah; Mastrolorenzo, Luca; Matsushita, Takashi; Nash, Jordan; Nikitenko, Alexander; Palladino, Vito; Pesaresi, Mark; Raymond, David Mark; Richards, Alexander; Rose, Andrew; Scott, Edward; Seez, Christopher; Shtipliyski, Antoni; Summers, Sioni; Tapper, Alexander; Uchida, Kirika; Vazquez Acosta, Monica; Virdee, Tejinder; Wardle, Nicholas; Winterbottom, Daniel; Wright, Jack; Zenz, Seth Conrad; Cole, Joanne; Hobson, Peter R; Khan, Akram; Kyberd, Paul; Reid, Ivan; Teodorescu, Liliana; Zahid, Sema; Borzou, Ahmad; Call, Kenneth; Dittmann, Jay; Hatakeyama, Kenichi; Liu, Hongxuan; Pastika, Nathaniel; Smith, Caleb; Bartek, Rachel; Dominguez, Aaron; Buccilli, Andrew; Cooper, Seth; Henderson, Conor; Rumerio, Paolo; West, Christopher; Arcaro, Daniel; Avetisyan, Aram; Bose, Tulika; Gastler, Daniel; Rankin, Dylan; Richardson, Clint; Rohlf, James; Sulak, Lawrence; Zou, David; Benelli, Gabriele; Cutts, David; Garabedian, Alex; Hadley, Mary; Hakala, John; Heintz, Ulrich; Hogan, Julie Managan; Kwok, Ka Hei Martin; Laird, Edward; Landsberg, Greg; Lee, Jangbae; Mao, Zaixing; Narain, Meenakshi; Pazzini, Jacopo; Piperov, Stefan; Sagir, Sinan; Syarif, Rizki; Yu, David; Band, Reyer; Brainerd, Christopher; Breedon, Richard; Burns, Dustin; Calderon De La Barca Sanchez, Manuel; Chertok, Maxwell; Conway, John; Conway, Rylan; Cox, Peter Timothy; Erbacher, Robin; Flores, Chad; Funk, Garrett; Ko, Winston; Lander, Richard; Mclean, Christine; Mulhearn, Michael; Pellett, Dave; Pilot, Justin; Shalhout, Shalhout; Shi, Mengyao; Smith, John; Stolp, Dustin; Tos, Kyle; Tripathi, Mani; Wang, Zhangqier; Bachtis, Michail; Bravo, Cameron; Cousins, Robert; Dasgupta, Abhigyan; Florent, Alice; Hauser, Jay; Ignatenko, Mikhail; Mccoll, Nickolas; Regnard, Simon; Saltzberg, David; Schnaible, Christian; Valuev, Vyacheslav; Bouvier, Elvire; Burt, Kira; Clare, Robert; Ellison, John Anthony; Gary, J William; Ghiasi Shirazi, Seyyed Mohammad Amin; Hanson, Gail; Heilman, Jesse; Karapostoli, Georgia; Kennedy, Elizabeth; Lacroix, Florent; Long, Owen Rosser; Olmedo Negrete, Manuel; Paneva, Mirena Ivova; Si, Weinan; Wang, Long; Wei, Hua; Wimpenny, Stephen; Yates, Brent; Branson, James G; Cittolin, Sergio; Derdzinski, Mark; Gerosa, Raffaele; Gilbert, Dylan; Hashemi, Bobak; Holzner, André; Klein, Daniel; Kole, Gouranga; Krutelyov, Vyacheslav; Letts, James; Macneill, Ian; Masciovecchio, Mario; Olivito, Dominick; Padhi, Sanjay; Pieri, Marco; Sani, Matteo; Sharma, Vivek; Simon, Sean; Tadel, Matevz; Vartak, Adish; Wasserbaech, Steven; Wood, John; Würthwein, Frank; Yagil, Avraham; Zevi Della Porta, Giovanni; Amin, Nick; Bhandari, Rohan; Bradmiller-Feld, John; Campagnari, Claudio; Dishaw, Adam; Dutta, Valentina; Franco Sevilla, Manuel; Golf, Frank; Gouskos, Loukas; Heller, Ryan; Incandela, Joe; Ovcharova, Ana; Qu, Huilin; Richman, Jeffrey; Stuart, David; Suarez, Indara; Yoo, Jaehyeok; Anderson, Dustin; Bornheim, Adolf; Lawhorn, Jay Mathew; Newman, Harvey B; Nguyen, Thong; Pena, Cristian; Spiropulu, Maria; Vlimant, Jean-Roch; Xie, Si; Zhang, Zhicai; Zhu, Ren-Yuan; Andrews, Michael Benjamin; Ferguson, Thomas; Mudholkar, Tanmay; Paulini, Manfred; Russ, James; Sun, Menglei; Vogel, Helmut; Vorobiev, Igor; Weinberg, Marc; Cumalat, John Perry; Ford, William T; Jensen, Frank; Johnson, Andrew; Krohn, Michael; Leontsinis, Stefanos; Mulholland, Troy; Stenson, Kevin; Wagner, Stephen Robert; Alexander, James; Chaves, Jorge; Chu, Jennifer; Dittmer, Susan; Mcdermott, Kevin; Mirman, Nathan; Patterson, Juliet Ritchie; Quach, Dan; Rinkevicius, Aurelijus; Ryd, Anders; Skinnari, Louise; Soffi, Livia; Tan, Shao Min; Tao, Zhengcheng; Thom, Julia; Tucker, Jordan; Wittich, Peter; Zientek, Margaret; Abdullin, Salavat; Albrow, Michael; Alyari, Maral; Apollinari, Giorgio; Apresyan, Artur; Apyan, Aram; Banerjee, Sunanda; Bauerdick, Lothar AT; Beretvas, Andrew; Berryhill, Jeffrey; Bhat, Pushpalatha C; Bolla, Gino; Burkett, Kevin; Butler, Joel Nathan; Canepa, Anadi; Cerati, Giuseppe Benedetto; Cheung, Harry; Chlebana, Frank; Cremonesi, Matteo; Duarte, Javier; Elvira, Victor Daniel; Freeman, Jim; Gecse, Zoltan; Gottschalk, Erik; Gray, Lindsey; Green, Dan; Grünendahl, Stefan; Gutsche, Oliver; Harris, Robert M; Hasegawa, Satoshi; Hirschauer, James; Hu, Zhen; Jayatilaka, Bodhitha; Jindariani, Sergo; Johnson, Marvin; Joshi, Umesh; Klima, Boaz; Kreis, Benjamin; Lammel, Stephan; Lincoln, Don; Lipton, Ron; Liu, Miaoyuan; Liu, Tiehui; Lopes De Sá, Rafael; Lykken, Joseph; Maeshima, Kaori; Magini, Nicolo; Marraffino, John Michael; Mason, David; McBride, Patricia; Merkel, Petra; Mrenna, Stephen; Nahn, Steve; O'Dell, Vivian; Pedro, Kevin; Prokofyev, Oleg; Rakness, Gregory; Ristori, Luciano; Schneider, Basil; Sexton-Kennedy, Elizabeth; Soha, Aron; Spalding, William J; Spiegel, Leonard; Stoynev, Stoyan; Strait, James; Strobbe, Nadja; Taylor, Lucas; Tkaczyk, Slawek; Tran, Nhan Viet; Uplegger, Lorenzo; Vaandering, Eric Wayne; Vernieri, Caterina; Verzocchi, Marco; Vidal, Richard; Wang, Michael; Weber, Hannsjoerg Artur; Whitbeck, Andrew; Acosta, Darin; Avery, Paul; Bortignon, Pierluigi; Bourilkov, Dimitri; Brinkerhoff, Andrew; Carnes, Andrew; Carver, Matthew; Curry, David; Field, Richard D; Furic, Ivan-Kresimir; Gleyzer, Sergei V; Joshi, Bhargav Madhusudan; Konigsberg, Jacobo; Korytov, Andrey; Kotov, Khristian; Ma, Peisen; Matchev, Konstantin; Mei, Hualin; Mitselmakher, Guenakh; Shi, Kun; Sperka, David; Terentyev, Nikolay; Thomas, Laurent; Wang, Jian; Wang, Sean-Jiun; Yelton, John; Joshi, Yagya Raj; Linn, Stephan; Markowitz, Pete; Rodriguez, Jorge Luis; Ackert, Andrew; Adams, Todd; Askew, Andrew; Hagopian, Sharon; Hagopian, Vasken; Johnson, Kurtis F; Kolberg, Ted; Martinez, German; Perry, Thomas; Prosper, Harrison; Saha, Anirban; Santra, Arka; Sharma, Varun; Yohay, Rachel; Baarmand, Marc M; Bhopatkar, Vallary; Colafranceschi, Stefano; Hohlmann, Marcus; Noonan, Daniel; Roy, Titas; Yumiceva, Francisco; Adams, Mark Raymond; Apanasevich, Leonard; Berry, Douglas; Betts, Russell Richard; Cavanaugh, Richard; Chen, Xuan; Evdokimov, Olga; Gerber, Cecilia Elena; Hangal, Dhanush Anil; Hofman, David Jonathan; Jung, Kurt; Kamin, Jason; Sandoval Gonzalez, Irving Daniel; Tonjes, Marguerite; Trauger, Hallie; Varelas, Nikos; Wang, Hui; Wu, Zhenbin; Zhang, Jingyu; Bilki, Burak; Clarida, Warren; Dilsiz, Kamuran; Durgut, Süleyman; Gandrajula, Reddy Pratap; Haytmyradov, Maksat; Khristenko, Viktor; Merlo, Jean-Pierre; Mermerkaya, Hamit; Mestvirishvili, Alexi; Moeller, Anthony; Nachtman, Jane; Ogul, Hasan; Onel, Yasar; Ozok, Ferhat; Penzo, Aldo; Snyder, Christina; Tiras, Emrah; Wetzel, James; Yi, Kai; Blumenfeld, Barry; Cocoros, Alice; Eminizer, Nicholas; Fehling, David; Feng, Lei; Gritsan, Andrei; Maksimovic, Petar; Roskes, Jeffrey; Sarica, Ulascan; Swartz, Morris; Xiao, Meng; You, Can; Al-bataineh, Ayman; Baringer, Philip; Bean, Alice; Boren, Samuel; Bowen, James; Castle, James; Khalil, Sadia; Kropivnitskaya, Anna; Majumder, Devdatta; Mcbrayer, William; Murray, Michael; Royon, Christophe; Sanders, Stephen; Schmitz, Erich; Tapia Takaki, Daniel; Wang, Quan; Ivanov, Andrew; Kaadze, Ketino; Maravin, Yurii; Mohammadi, Abdollah; Saini, Lovedeep Kaur; Skhirtladze, Nikoloz; Toda, Sachiko; Rebassoo, Finn; Wright, Douglas; Anelli, Christopher; Baden, Drew; Baron, Owen; Belloni, Alberto; Eno, Sarah Catherine; Feng, Yongbin; Ferraioli, Charles; Hadley, Nicholas John; Jabeen, Shabnam; Jeng, Geng-Yuan; Kellogg, Richard G; Kunkle, Joshua; Mignerey, Alice; Ricci-Tam, Francesca; Shin, Young Ho; Skuja, Andris; Tonwar, Suresh C; Abercrombie, Daniel; Allen, Brandon; Azzolini, Virginia; Barbieri, Richard; Baty, Austin; Bi, Ran; Brandt, Stephanie; Busza, Wit; Cali, Ivan Amos; D'Alfonso, Mariarosaria; Demiragli, Zeynep; Gomez Ceballos, Guillelmo; Goncharov, Maxim; Hsu, Dylan; Hu, Miao; Iiyama, Yutaro; Innocenti, Gian Michele; Klute, Markus; Kovalskyi, Dmytro; Lai, Yue Shi; Lee, Yen-Jie; Levin, Andrew; Luckey, Paul David; Maier, Benedikt; Marini, Andrea Carlo; Mcginn, Christopher; Mironov, Camelia; Narayanan, Siddharth; Niu, Xinmei; Paus, Christoph; Roland, Christof; Roland, Gunther; Salfeld-Nebgen, Jakob; Stephans, George; Tatar, Kaya; Velicanu, Dragos; Wang, Jing; Wang, Ta-Wei; Wyslouch, Bolek; Benvenuti, Alberto; Chatterjee, Rajdeep Mohan; Evans, Andrew; Hansen, Peter; Hiltbrand, Joshua; Kalafut, Sean; Kubota, Yuichi; Lesko, Zachary; Mans, Jeremy; Nourbakhsh, Shervin; Ruckstuhl, Nicole; Rusack, Roger; Turkewitz, Jared; Wadud, Mohammad Abrar; Acosta, John Gabriel; Oliveros, Sandra; Avdeeva, Ekaterina; Bloom, Kenneth; Claes, Daniel R; Fangmeier, Caleb; Gonzalez Suarez, Rebeca; Kamalieddin, Rami; Kravchenko, Ilya; Monroy, Jose; Siado, Joaquin Emilo; Snow, Gregory R; Stieger, Benjamin; Dolen, James; Godshalk, Andrew; Harrington, Charles; Iashvili, Ia; Nguyen, Duong; Parker, Ashley; Rappoccio, Salvatore; Roozbahani, Bahareh; Alverson, George; Barberis, Emanuela; Freer, Chad; Hortiangtham, Apichart; Massironi, Andrea; Morse, David Michael; Orimoto, Toyoko; Teixeira De Lima, Rafael; Trocino, Daniele; Wamorkar, Tanvi; Wang, Bingran; Wisecarver, Andrew; Wood, Darien; Bhattacharya, Saptaparna; Charaf, Otman; Hahn, Kristan Allan; Mucia, Nicholas; Odell, Nathaniel; Schmitt, Michael Henry; Sung, Kevin; Trovato, Marco; Velasco, Mayda; Bucci, Rachael; Dev, Nabarun; Hildreth, Michael; Hurtado Anampa, Kenyi; Jessop, Colin; Karmgard, Daniel John; Kellams, Nathan; Lannon, Kevin; Li, Wenzhao; Loukas, Nikitas; Marinelli, Nancy; Meng, Fanbo; Mueller, Charles; Musienko, Yuri; Planer, Michael; Reinsvold, Allison; Ruchti, Randy; Siddireddy, Prasanna; Smith, Geoffrey; Taroni, Silvia; Wayne, Mitchell; Wightman, Andrew; Wolf, Matthias; Woodard, Anna; Alimena, Juliette; Antonelli, Louis; Bylsma, Ben; Durkin, Lloyd Stanley; Flowers, Sean; Francis, Brian; Hart, Andrew; Hill, Christopher; Ji, Weifeng; Liu, Bingxuan; Luo, Wuming; Winer, Brian L; Wulsin, Howard Wells; Cooperstein, Stephane; Driga, Olga; Elmer, Peter; Hardenbrook, Joshua; Hebda, Philip; Higginbotham, Samuel; Kalogeropoulos, Alexis; Lange, David; Luo, Jingyu; Marlow, Daniel; Mei, Kelvin; Ojalvo, Isabel; Olsen, James; Palmer, Christopher; Piroué, Pierre; Stickland, David; Tully, Christopher; Malik, Sudhir; Norberg, Scarlet; Barker, Anthony; Barnes, Virgil E; Das, Souvik; Folgueras, Santiago; Gutay, Laszlo; Jha, Manoj; Jones, Matthew; Jung, Andreas Werner; Khatiwada, Ajeeta; Miller, David Harry; Neumeister, Norbert; Peng, Cheng-Chieh; Qiu, Hao; Schulte, Jan-Frederik; Sun, Jian; Wang, Fuqiang; Xiao, Rui; Xie, Wei; Cheng, Tongguang; Parashar, Neeti; Stupak, John; Chen, Zhenyu; Ecklund, Karl Matthew; Freed, Sarah; Geurts, Frank JM; Guilbaud, Maxime; Kilpatrick, Matthew; Li, Wei; Michlin, Benjamin; Padley, Brian Paul; Roberts, Jay; Rorie, Jamal; Shi, Wei; Tu, Zhoudunming; Zabel, James; Zhang, Aobo; Bodek, Arie; de Barbaro, Pawel; Demina, Regina; Duh, Yi-ting; Ferbel, Thomas; Galanti, Mario; Garcia-Bellido, Aran; Han, Jiyeon; Hindrichs, Otto; Khukhunaishvili, Aleko; Lo, Kin Ho; Tan, Ping; Verzetti, Mauro; Ciesielski, Robert; Goulianos, Konstantin; Mesropian, Christina; Agapitos, Antonis; Chou, John Paul; Gershtein, Yuri; Gómez Espinosa, Tirso Alejandro; Halkiadakis, Eva; Heindl, Maximilian; Hughes, Elliot; Kaplan, Steven; Kunnawalkam Elayavalli, Raghav; Kyriacou, Savvas; Lath, Amitabh; Montalvo, Roy; Nash, Kevin; Osherson, Marc; Saka, Halil; Salur, Sevil; Schnetzer, Steve; Sheffield, David; Somalwar, Sunil; Stone, Robert; Thomas, Scott; Thomassen, Peter; Walker, Matthew; Delannoy, Andrés G; Foerster, Mark; Heideman, Joseph; Riley, Grant; Rose, Keith; Spanier, Stefan; Thapa, Krishna; Bouhali, Othmane; Castaneda Hernandez, Alfredo; Celik, Ali; Dalchenko, Mykhailo; De Mattia, Marco; Delgado, Andrea; Dildick, Sven; Eusebi, Ricardo; Gilmore, Jason; Huang, Tao; Kamon, Teruki; Mueller, Ryan; Pakhotin, Yuriy; Patel, Rishi; Perloff, Alexx; Perniè, Luca; Rathjens, Denis; Safonov, Alexei; Tatarinov, Aysen; Ulmer, Keith; Akchurin, Nural; Damgov, Jordan; De Guio, Federico; Dudero, Phillip Russell; Faulkner, James; Gurpinar, Emine; Kunori, Shuichi; Lamichhane, Kamal; Lee, Sung Won; Libeiro, Terence; Mengke, Tielige; Muthumuni, Samila; Peltola, Timo; Undleeb, Sonaina; Volobouev, Igor; Wang, Zhixing; Greene, Senta; Gurrola, Alfredo; Janjam, Ravi; Johns, Willard; Maguire, Charles; Melo, Andrew; Ni, Hong; Padeken, Klaas; Sheldon, Paul; Tuo, Shengquan; Velkovska, Julia; Xu, Qiao; Arenton, Michael Wayne; Barria, Patrizia; Cox, Bradley; Hirosky, Robert; Joyce, Matthew; Ledovskoy, Alexander; Li, Hengne; Neu, Christopher; Sinthuprasith, Tutanon; Wang, Yanchu; Wolfe, Evan; Xia, Fan; Harr, Robert; Karchin, Paul Edmund; Poudyal, Nabin; Sturdy, Jared; Thapa, Prakash; Zaleski, Shawn; Brodski, Michael; Buchanan, James; Caillol, Cécile; Dasu, Sridhara; Dodd, Laura; Duric, Senka; Gomber, Bhawna; Grothe, Monika; Herndon, Matthew; Hervé, Alain; Hussain, Usama; Klabbers, Pamela; Lanaro, Armando; Levine, Aaron; Long, Kenneth; Loveless, Richard; Ruggles, Tyler; Savin, Alexander; Smith, Nicholas; Smith, Wesley H; Taylor, Devin; Woods, Nathaniel
2017-01-01
Event-by-event fluctuations in the elliptic-flow coefficient $v_2$ are studied in PbPb collisions at $\\sqrt{\\smash[b]{s_{_\\text{NN}}}} = $ 5.02 TeV using the CMS detector at the CERN LHC. Elliptic-flow probability distributions ${p}(v_2)$ for charged particles with transverse momentum 0.3 $ < {p_{\\mathrm{T}}} < $ 3.0 GeV/$c$ and pseudorapidity $ | \\eta | < $ 1.0 are determined for different collision centrality classes. The moments of the ${p}(v_2)$ distributions are used to calculate the $v_{2}$ coefficients based on cumulant orders 2, 4, 6, and 8. A rank ordering of the higher-order cumulant results and nonzero standardized skewness values obtained for the ${p}(v_2)$ distributions indicate non-Gaussian initial-state fluctuation behavior. Bessel-Gaussian and elliptic power fits to the flow distributions are studied to characterize the initial-state spatial anisotropy.
Energy Technology Data Exchange (ETDEWEB)
Sirunyan, Albert M; et al.
2017-11-15
Event-by-event fluctuations in the elliptic-flow coefficient $v_2$ are studied in PbPb collisions at $\\sqrt{s_{_\\text{NN}}} = 5.02$ TeV using the CMS detector at the CERN LHC. Elliptic-flow probability distributions ${p}(v_2)$ for charged particles with transverse momentum 0.3$< p_\\mathrm{T} <$3.0 GeV and pseudorapidity $| \\eta | <$ 1.0 are determined for different collision centrality classes. The moments of the ${p}(v_2)$ distributions are used to calculate the $v_{2}$ coefficients based on cumulant orders 2, 4, 6, and 8. A rank ordering of the higher-order cumulant results and nonzero standardized skewness values obtained for the ${p}(v_2)$ distributions indicate non-Gaussian initial-state fluctuation behavior. Bessel-Gaussian and elliptic power fits to the flow distributions are studied to characterize the initial-state spatial anisotropy.
Gao, Xian; Kobayashi, Tsutomu; Yamaguchi, Masahide; Yokoyama, Jun'ichi
2011-11-18
We completely clarify the feature of primordial non-Gaussianities of tensor perturbations in the most general single-field inflation model with second-order field equations. It is shown that the most general cubic action for the tensor perturbation h(ij) is composed only of two contributions, one with two spacial derivatives and the other with one time derivative on each h(ij). The former is essentially identical to the cubic term that appears in Einstein gravity and predicts a squeezed shape, while the latter newly appears in the presence of the kinetic coupling to the Einstein tensor and predicts an equilateral shape. Thus, only two shapes appear in the graviton bispectrum of the most general single-field inflation model, which could open a new clue to the identification of inflationary gravitational waves in observations of cosmic microwave background anisotropies as well as direct detection experiments.
Huang, N. E.; Long, S. R.; Bliven, L. F.; Tung, C.-C.
1984-01-01
On the basis of the mapping method developed by Huang et al. (1983), an analytic expression for the non-Gaussian joint probability density function of slope and elevation for nonlinear gravity waves is derived. Various conditional and marginal density functions are also obtained through the joint density function. The analytic results are compared with a series of carefully controlled laboratory observations, and good agreement is noted. Furthermore, the laboratory wind wave field observations indicate that the capillary or capillary-gravity waves may not be the dominant components in determining the total roughness of the wave field. Thus, the analytic results, though derived specifically for the gravity waves, may have more general applications.
Adur, Rohan; Du, Chunhui; Manuilov, Sergei A.; Wang, Hailong; Yang, Fengyuan; Pelekhov, Denis V.; Hammel, P. Chris
2015-05-01
The dipole field from a probe magnet can be used to localize a discrete spectrum of standing spin wave modes in a continuous ferromagnetic thin film without lithographic modification to the film. Obtaining the resonance field for a localized mode is not trivial due to the effect of the confined and inhomogeneous magnetization precession. We compare the results of micromagnetic and analytic methods to find the resonance field of localized modes in a ferromagnetic thin film, and investigate the accuracy of these methods by comparing with a numerical minimization technique that assumes Bessel function modes with pinned boundary conditions. We find that the micromagnetic technique, while computationally more intensive, reveals that the true magnetization profiles of localized modes are similar to Bessel functions with gradually decaying dynamic magnetization at the mode edges. We also find that an analytic solution, which is simple to implement and computationally much faster than other methods, accurately describes the resonance field of localized modes when exchange fields are negligible, and demonstrating the accessibility of localized mode analysis.
International Nuclear Information System (INIS)
Funabishi, K.; Hamill, W.H.
The continuous-time-random-walk (CTRW) model which was developed for electron scavenging reactions in polar glasses is extended to the phenomenon of spectral relaxation of electrons in shallow traps esub(t) - in a wider range of systems. The central role of electron-phonon coupling in understanding the initial electron localization, the ''pre-existing trap'', and electron transfer processes are emphasized. The reactivity of esub(t) - with scavengers, including protons, is discussed in terms of the theory of multi-phonon non-radiative transitions. (author)
Pothof, F.; Bonini, L.; Lanzilotto, M.; Livi, A.; Fogassi, L.; Orban, G. A.; Paul, O.; Ruther, P.
2016-08-01
Objective. Drug resistant focal epilepsy can be treated by resecting the epileptic focus requiring a precise focus localisation using stereoelectroencephalography (SEEG) probes. As commercial SEEG probes offer only a limited spatial resolution, probes of higher channel count and design freedom enabling the incorporation of macro and microelectrodes would help increasing spatial resolution and thus open new perspectives for investigating mechanisms underlying focal epilepsy and its treatment. This work describes a new fabrication process for SEEG probes with materials and dimensions similar to clinical probes enabling recording single neuron activity at high spatial resolution. Approach. Polyimide is used as a biocompatible flexible substrate into which platinum electrodes and leads are integrated with a minimal feature size of 5 μm. The polyimide foils are rolled into the cylindrical probe shape at a diameter of 0.8 mm. The resulting probe features match those of clinically approved devices. Tests in saline solution confirmed the probe stability and functionality. Probes were implanted into the brain of one monkey (Macaca mulatta), trained to perform different motor tasks. Suitable configurations including up to 128 electrode sites allow the recording of task-related neuronal signals. Main results. Probes with 32 and 64 electrode sites were implanted in the posterior parietal cortex. Local field potentials and multi-unit activity were recorded as early as one hour after implantation. Stable single-unit activity was achieved for up to 26 days after implantation of a 64-channel probe. All recorded signals showed modulation during task execution. Significance. With the novel probes it is possible to record stable biologically relevant data over a time span exceeding the usual time needed for epileptic focus localisation in human patients. This is the first time that single units are recorded along cylindrical polyimide probes chronically implanted 22 mm deep into the
Czech Academy of Sciences Publication Activity Database
Bříza, T.; Rimpelová, S.; Králová, Jarmila; Záruba, K.; Kejík, Z.; Ruml, T.; Martásek, P.; Král, V.
2014-01-01
Roč. 107, August 2014 (2014), s. 51-59 ISSN 0143-7208 R&D Projects: GA AV ČR KAN200100801; GA ČR(CZ) GAP303/11/1291; GA MŠk(CZ) CZ.01.05/2.1.00/01.00.30; GA MŠk(CZ) CZ.1.07/2.300/30.0060 Institutional support: RVO:68378050 Keywords : Pentamethinium salts * Fluorescent probes * Mitochondria * Cardiolipin Photostability * Organelle imaging Subject RIV: CE - Biochemistry Impact factor: 3.966, year: 2014
The generalized Cauchy relation: a probe for local structure in materials with isotropic symmetry
Energy Technology Data Exchange (ETDEWEB)
Bactavatchalou, R [Laboratoire Europeen de Recherche Universitaire Saarland- Lorraine- Luxembourg at Universitaet des Saarlandes (Luxembourg); Alnot, P [Universite Henri Poincare, Nancy I (France); Bailer, J [Universite du Luxembourg (Luxembourg); Kolle, M [Laboratoire Europeen de Recherche Universitaire Saarland- Lorraine- Luxembourg at Universitaet des Saarlandes (Luxembourg); Mueller, U [Laboratoire Europeen de Recherche Universitaire Saarland- Lorraine- Luxembourg at Universitaet des Saarlandes (Luxembourg); Philipp, M [Laboratoire Europeen de Recherche Universitaire Saarland- Lorraine- Luxembourg at Universitaet des Saarlandes (Luxembourg); Possart, W [Laboratoire Europeen de Recherche Universitaire Saarland- Lorraine- Luxembourg at Universitaet des Saarlandes (Luxembourg); Rouxel, D [Universite Henri Poincare, Nancy I (France); Sanctuary, R [Universite du Luxembourg (Luxembourg); Tschoepe, A [Laboratoire Europeen de Recherche Universitaire Saarland- Lorraine- Luxembourg at Universitaet des Saarlandes (Luxembourg); Vergnat, Ch [Laboratoire Europeen de Recherche Universitaire Saarland- Lorraine- Luxembourg at Universitaet des Saarlandes (Luxembourg); Wetzel, B [Institut fuer Verbundwerkstoffe TU Kaiserslautern 67663 Kaiserslautern (Germany); Krueger, J K [Laboratoire Europeen de Recherche Universitaire Saarland- Lorraine- Luxembourg at Universitaet des Saarlandes (Luxembourg)
2006-05-15
The elastic properties of the isotropic state of condensed matter are given by the elastic constants ell and c44. In the liquid state the static shear stiffness c44 vanishes whereas at sufficient high probe frequencies a dynamic shear stiffness may appear. In that latter case the question about the existence of a Cauchy relation appears. It will be shown that a pure Cauchy relation can appear only under special conditions which are rarely fulfilled. For all investigated materials, including ceramics, liquids and glasses, a linear relation between ell and c44 called generalized Cauchy relation is observed, which, surprisingly, follows a linear transformation.
Ganser, Christian; Czibula, Caterina; Tscharnuter, Daniel; Schöberl, Thomas; Teichert, Christian; Hirn, Ulrich
2017-12-20
Viscoelastic properties are often measured using probe based techniques such as nanoindentation (NI) and atomic force microscopy (AFM). Rarely, however, are these methods verified. In this article, we present a method that combines contact mechanics with a viscoelastic model (VEM) composed of springs and dashpots. We further show how to use this model to determine viscoelastic properties from creep curves recorded by a probe based technique. We focus on using the standard linear solid model and the generalized Maxwell model of order 2. The method operates in the range of 0.01 Hz to 1 Hz. Our approach is suitable for rough surfaces by providing a defined contact area using plastic pre-deformation of the material. The very same procedure is used to evaluate AFM based measurements as well as NI measurements performed on polymer samples made from poly(methyl methacrylate) and polycarbonate. The results of these measurements are then compared to those obtained by tensile creep tests also performed on the same samples. It is found that the tensile test results differ considerably from the results obtained by AFM and NI methods. The similarity between the AFM results and NI results suggests that the proposed method is capable of yielding results comparable to NI but with the advantage of the imaging possibilities of AFM. Furthermore, all three methods allowed a clear distinction between PC and PMMA by means of their respective viscoelastic properties.
Tummala, Sudhakar; Palomares, Jose; Kang, Daniel W; Park, Bumhee; Woo, Mary A; Harper, Ronald M; Kumar, Rajesh
2016-01-01
Obstructive sleep apnea (OSA) patients show brain structural injury and functional deficits in autonomic, affective, and cognitive regulatory sites, as revealed by mean diffusivity (MD) and other imaging procedures. The time course and nature of gray and white matter injury can be revealed in more detail with mean kurtosis (MK) procedures, which can differentiate acute from chronic injury, and better show extent of damage over MD procedures. Our objective was to examine global and regional MK changes in newly diagnosed OSA, relative to control subjects. Two diffusion kurtosis image series were collected from 22 recently-diagnosed, treatment-naïve OSA and 26 control subjects using a 3.0-Tesla MRI scanner. MK maps were generated, normalized to a common space, smoothed, and compared voxel-by-voxel between groups using analysis of covariance (covariates; age, sex). No age or sex differences appeared, but body mass index, sleep, neuropsychologic, and cognitive scores significantly differed between groups. MK values were significantly increased globally in OSA over controls, and in multiple localized sites, including the basal forebrain, extending to the hypothalamus, hippocampus, thalamus, insular cortices, basal ganglia, limbic regions, cerebellar areas, parietal cortices, ventral temporal lobe, ventrolateral medulla, and midline pons. Multiple sites, including the insular cortices, ventrolateral medulla, and midline pons showed more injury over previously identified damage with MD procedures, with damage often lateralized. Global mean kurtosis values are significantly increased in obstructive sleep apnea (OSA), suggesting acute tissue injury, and these changes are principally localized in critical sites mediating deficient functions in the condition. The mechanisms for injury likely include altered perfusion and hypoxemia-induced processes, leading to acute tissue changes in recently diagnosed OSA. © 2016 Associated Professional Sleep Societies, LLC.
Graphene as a local probe to investigate near-field properties of plasmonic nanostructures
Wasserroth, Sören; Bisswanger, Timo; Mueller, Niclas S.; Kusch, Patryk; Heeg, Sebastian; Clark, Nick; Schedin, Fredrik; Gorbachev, Roman; Reich, Stephanie
2018-04-01
Light interacting with metallic nanoparticles creates a strongly localized near-field around the particle that enhances inelastic light scattering by several orders of magnitude. Surface-enhanced Raman scattering describes the enhancement of the Raman intensity by plasmonic nanoparticles. We present an extensive Raman characterization of a plasmonic gold nanodimer covered with graphene. Its two-dimensional nature and energy-independent optical properties make graphene an excellent material for investigating local electromagnetic near-fields. We show the localization of the near-field of the plasmonic dimer by spatial Raman measurements. Energy- and polarization-dependent measurements reveal the local near-field resonance of the plasmonic system. To investigate the far-field resonance we perform dark-field spectroscopy and find that near-field and far-field resonance energies differ by 170 meV, much more than expected from the model of a damped oscillator (40 meV).
Energy Technology Data Exchange (ETDEWEB)
Yan, Ren; Haopeng, Pang; Xiaoyuan, Feng; Jiawen, Zhang; Zhenwei, Yao [Fudan University, Department of Radiology, Huashan Hospital, Shanghai (China); Jinsong, Wu; Chengjun, Yao; Tianming, Qiu [Fudan University, Department of Neurosurgery, Huashan Hospital, Shanghai (China); Ji, Xiong [Fudan University, Department of Neuropathology, Huashan Hospital, Shanghai (China); Mao, Sheng; Yueyue, Ding [Department of Imaging, Suzhou Children' s Hospital, Suzhou, Jiangsu (China); Yong, Zhang [MR Research, GE Healthcare, Shanghai (China); Jianfeng, Luo [Fudan University, Department of Biostatistics, Public Health School, Shanghai (China)
2016-02-15
This study was conducted to compare the association of Gaussian and non-Gaussian magnetic resonance imaging (MRI)-derived parameters with histologic grade and MIB-1 (Ki-67 labeling) index (MI) in brain glioma. Sixty-five patients with pathologically confirmed glioma, who underwent diffusion-weighted MRI with 2 b values (0, 1000 s/mm{sup 2}) and 22 b values (≤5000 s/mm{sup 2}), respectively, were divided into three groups of grade II (n = 35), grade III (n = 8), and grade IV (n = 22). Comparisons by two groups were made for apparent diffusion coefficient (ADC), slow diffusion coefficient (Dslow), distributed diffusion coefficient (DDC), and heterogeneity index α. Analyses of receiver operating characteristic (ROC) curve were performed to maximize the area under the curve (AUC) for differentiating grade III + IV (high-grade glioma, HGG) from grade II (low-grade glioma, LGG) and grade IV (glioblastoma multiforme, GBM) from grade II + III (other grade glioma, OGG). Correlations with MI were analyzed for the MRI parameters. On tumor regions, the values of ADC, Dslow, DDC, and α were significantly higher in grade II [(1.37 ± 0.29, 0.70 ± 0.11, 1.39 ± 0.34) (x 10{sup -3} mm{sup 2}/s) and 0.88 ± 0.05, respectively] than in grade III [(0.99 ± 0.13, 0.55 ± 0.07, 1.04 ± 0.20) (x 10{sup -3} mm{sup 2}/s) and 0.80 ± 0.03, respectively] and grade IV [(1.03 ± 0.14, 0.50 ± 0.05, 1.02 ± 0.16) (x 10{sup -3} mm{sup 2}/s) and 0.76 ± 0.04, respectively] (all P < 0.001). The parameter α showed the highest AUCs of 0.950 and 0.922 in discriminating HGG from LGG and GBM from OGG, respectively. Significant correlations with histologic grade and MI were observed for the MRI parameters. The non-Gaussian MRI-derived parameters α and Dslow are superior to ADC in glioma grading, which are comparable with ADC as reliable biomarkers in noninvasively predicting the proliferation level of glioma malignancy. (orig.)
International Nuclear Information System (INIS)
Yan, Ren; Haopeng, Pang; Xiaoyuan, Feng; Jiawen, Zhang; Zhenwei, Yao; Jinsong, Wu; Chengjun, Yao; Tianming, Qiu; Ji, Xiong; Mao, Sheng; Yueyue, Ding; Yong, Zhang; Jianfeng, Luo
2016-01-01
This study was conducted to compare the association of Gaussian and non-Gaussian magnetic resonance imaging (MRI)-derived parameters with histologic grade and MIB-1 (Ki-67 labeling) index (MI) in brain glioma. Sixty-five patients with pathologically confirmed glioma, who underwent diffusion-weighted MRI with 2 b values (0, 1000 s/mm 2 ) and 22 b values (≤5000 s/mm 2 ), respectively, were divided into three groups of grade II (n = 35), grade III (n = 8), and grade IV (n = 22). Comparisons by two groups were made for apparent diffusion coefficient (ADC), slow diffusion coefficient (Dslow), distributed diffusion coefficient (DDC), and heterogeneity index α. Analyses of receiver operating characteristic (ROC) curve were performed to maximize the area under the curve (AUC) for differentiating grade III + IV (high-grade glioma, HGG) from grade II (low-grade glioma, LGG) and grade IV (glioblastoma multiforme, GBM) from grade II + III (other grade glioma, OGG). Correlations with MI were analyzed for the MRI parameters. On tumor regions, the values of ADC, Dslow, DDC, and α were significantly higher in grade II [(1.37 ± 0.29, 0.70 ± 0.11, 1.39 ± 0.34) (x 10 -3 mm 2 /s) and 0.88 ± 0.05, respectively] than in grade III [(0.99 ± 0.13, 0.55 ± 0.07, 1.04 ± 0.20) (x 10 -3 mm 2 /s) and 0.80 ± 0.03, respectively] and grade IV [(1.03 ± 0.14, 0.50 ± 0.05, 1.02 ± 0.16) (x 10 -3 mm 2 /s) and 0.76 ± 0.04, respectively] (all P < 0.001). The parameter α showed the highest AUCs of 0.950 and 0.922 in discriminating HGG from LGG and GBM from OGG, respectively. Significant correlations with histologic grade and MI were observed for the MRI parameters. The non-Gaussian MRI-derived parameters α and Dslow are superior to ADC in glioma grading, which are comparable with ADC as reliable biomarkers in noninvasively predicting the proliferation level of glioma malignancy. (orig.)
Probing Anderson localization of light by weak non-linear effects
International Nuclear Information System (INIS)
Sperling, T; Bührer, W; Maret, G; Ackermann, M; Aegerter, C M
2014-01-01
Breakdown of wave transport due to strong disorder is a universal phenomenon known as Anderson localization (AL). It occurs because of the macroscopic population of reciprocal multiple scattering paths, which in three dimensional systems happens at a critical scattering strength. Intensities on these random loops should thus be highly increased relative to those of a diffusive sample. In order to highlight localized modes of light, we exploit the optical nonlinearities of TiO 2 . Power dependent and spectrally resolved time of flight distribution measurements in transmission through slabs of TiO 2 powders at various turbidities reveal that mostly long loops are affected by nonlinearities and that the deviations from diffusive transport observed at long times are due to these localized modes. Our data are a first step in the experimental investigation of the interplay between nonlinear effects and AL in 3D. (fast track communication)
Fluctuating local field method probed for a description of small classical correlated lattices
Rubtsov, Alexey N.
2018-05-01
Thermal-equilibrated finite classical lattices are considered as a minimal model of the systems showing an interplay between low-energy collective fluctuations and single-site degrees of freedom. Standard local field approach, as well as classical limit of the bosonic DMFT method, do not provide a satisfactory description of Ising and Heisenberg small lattices subjected to an external polarizing field. We show that a dramatic improvement can be achieved within a simple approach, in which the local field appears to be a fluctuating quantity related to the low-energy degree(s) of freedom.
DEFF Research Database (Denmark)
Longo Martins, Murillo; Eckert, Juergen; Jacobsen, Henrik
2017-01-01
Since potential changes in the dynamics and mobility of drugs upon complexation for delivery may affect their ultimate efficacy, we have investigated the dynamics of two local anesthetic molecules, bupivacaine (BVC, C18H28N2O) and ropivacaine (RVC, C17H26N2O), in both their crystalline forms...
DEFF Research Database (Denmark)
Torchio, R.; Boccato, S.; Cerantola, V.
2016-01-01
In this paper we present recent achievements in the field of investigation of the local, electronic and magnetic structure of the matter under extreme conditions of pressure and temperature. These results were obtained thanks to the coupling of a compact laser heating system to the energy-dispersive...
Bailey, Mandy; van Loon, Jacco Th.; Farhang, Amin; Javadi, Atefeh; Khosroshahi, Habib G.; Sarre, Peter J.; Smith, Keith T.
2016-01-01
Context. The Sun traverses a low-density, hot entity called the Local Bubble. Despite its relevance to life on Earth, the conditions in the Local Bubble and its exact configuration are not very well known. Besides that, there is some unknown interstellar substance that causes a host of absorption bands across the optical spectrum, called diffuse interstellar bands (DIBs). Aims: We have started a project to chart the Local Bubble in a novel way and learn more about the carriers of the DIBs, by using DIBs as tracers of diffuse gas and environmental conditions. Methods: We conducted a high signal-to-noise spectroscopic survey of 670 nearby early-type stars to map DIB absorption in and around the Local Bubble. The project started with a southern hemisphere survey conducted at the European Southern Observatory's New Technology Telescope and has since been extended to an all-sky survey using the Isaac Newton Telescope. Results: In this first paper in the series, we introduce the overall project and present the results from the southern heiphere survey. We make aviable a catalogue of equivalent-width measurements of the DIBs at 5780, 5797, 5850, 6196, 6203, 6270, 6283, and 6614 Å, of the interstellar Na I D lines at 5890 and 5896 Å, and of the stellar He I line at 5876 Å. We find that the 5780 Å DIB is relatively strong throughout, as compared to the 5797 Å DIB, but especially within the Local Bubble and at the interface iwth a more neutral medium. The 6203 Å DIB shows similar behaviour with respect to the 6196 Å DIB. Some nearby stars show surprisingly strong DIBs, whereas some distant stars show very weak DIBs, indicating small-scale structure within, as well as outside, the Local Bubble. The sight lines with non-detections trace the extent of the Local Bubble especially clearly and show it opening out into the halo. Conclusions: The Local Bubble has a wall that is in contact with hot gas and/or a harsh interstellar radiation field. That wall is perforated
Analysis of medical device materials with the local electrode atom probe
International Nuclear Information System (INIS)
Goodman, S.L.; Mengelt, T.J.; Ali, M.; Ulfig, R.M.; Martens, R.M.; Kelly, T.F.; Kostrna, S.L.P.; Kostrna, M.S.; Carmichael, W.J.
2004-01-01
Full text: As medical technology advances towards microsurgical and minimally invasive techniques, there is a drive to produce ever-smaller devices that demand higher material performance and hence enhanced nano and micro-scale control of material structure. These devices are made from stainless steel alloys, Nitinol, titanium, CoCrMo, and non-metals such as pyrolytic carbon and silicon. These applications are made possible due to suitable physical and mechanical properties, good corrosion resistance in biological environments, reasonable biocompatibility, and good manufacturability. With respect to the metals, the nano-structure and composition of the material surface, typically an oxide, is especially critical since biological responses and corrosion occur at the material-environment interface. Thus, there is an increasing need to understand the 3-D structure and composition of metallic biomaterials at the atomic scale. Three-dimensional atom probe microscopy can uniquely provide such atomic-level structural information. In the present study several of these medical device materials were examined. These include a 316L stainless steel alloy which is widely used in implanted spinal fixation devices, bone screws, cardiovascular and neurological stents, a cast CoCrMo acetabular hip cup of a Cormet metal-on-metal Hip Resurfacing System (Corin Group, Cirencester, England) that was rejected for clinical use, Nitinol wires specimens such as are used for stents and guide wires, and low temperature pyrolytic carbon as used in clinical heart valve prosthetics. (author)
Fast Magnetosonic Waves Observed by Van Allen Probes: Testing Local Wave Excitation Mechanism
Min, Kyungguk; Liu, Kaijun; Wang, Xueyi; Chen, Lunjin; Denton, Richard E.
2018-01-01
Linear Vlasov theory and particle-in-cell (PIC) simulations for electromagnetic fluctuations in a homogeneous, magnetized, and collisionless plasma are used to investigate a fast magnetosonic wave event observed by the Van Allen Probes. The fluctuating magnetic field observed exhibits a series of spectral peaks at harmonics of the proton cyclotron frequency Ωp and has a dominant compressional component, which can be classified as fast magnetosonic waves. Furthermore, the simultaneously observed proton phase space density exhibits positive slopes in the perpendicular velocity space, ∂fp/∂v⊥>0, which can be a source for these waves. Linear theory analyses and PIC simulations use plasma and field parameters measured in situ except that the modeled proton distribution is modified to have larger ∂fp/∂v⊥ under the assumption that the observed distribution corresponds to a marginally stable state when the distribution has already been scattered by the excited waves. The results show that the positive slope is the source of the proton cyclotron harmonic waves at propagation quasi-perpendicular to the background magnetic field, and as a result of interactions with the excited waves the evolving proton distribution progresses approximately toward the observed distribution.
International Nuclear Information System (INIS)
Nha, Hyunchul; Kim, Jaewan
2006-01-01
We derive a class of inequalities, from the uncertainty relations of the su(1,1) and the su(2) algebra in conjunction with partial transposition, that must be satisfied by any separable two-mode states. These inequalities are presented in terms of the su(2) operators J x =(a † b+ab † )/2, J y =(a † b-ab † )/2i, and the total photon number a +N b >. They include as special cases the inequality derived by Hillery and Zubairy [Phys. Rev. Lett. 96, 050503 (2006)], and the one by Agarwal and Biswas [New J. Phys. 7, 211 (2005)]. In particular, optimization over the whole inequalities leads to the criterion obtained by Agarwal and Biswas. We show that this optimal criterion can detect entanglement for a broad class of non-Gaussian entangled states, i.e., the su(2) minimum-uncertainty states. Experimental schemes to test the optimal criterion are also discussed, especially the one using linear optical devices and photodetectors
Energy Technology Data Exchange (ETDEWEB)
Jerome, Neil P.; Miyazaki, Keiko; Collins, David J.; Orton, Matthew R.; D' Arcy, James A.; Leach, Martin O. [Cancer Research UK Cancer Imaging Centre, Division of Radiotherapy and Imaging, The Institute of Cancer Research, London (United Kingdom); Wallace, Toni; Koh, Dow-Mu [Royal Marsden NHS Foundation Trust, Department of Radiology, Sutton, Surrey (United Kingdom); Moreno, Lucas [The Institute of Cancer Research, Paediatric Drug Development Team, Division of Cancer Therapeutics and Clinical Studies, London (United Kingdom); Hospital Nino Jesus, Madrid (Spain); Royal Marsden NHS Foundation Trust, Paediatric Drug Development Unit, Children and Young People' s Unit, Sutton, Surrey (United Kingdom); Pearson, Andrew D.J.; Marshall, Lynley V.; Carceller, Fernando; Zacharoulis, Stergios [The Institute of Cancer Research, Paediatric Drug Development Team, Division of Cancer Therapeutics and Clinical Studies, London (United Kingdom); Royal Marsden NHS Foundation Trust, Paediatric Drug Development Unit, Children and Young People' s Unit, Sutton, Surrey (United Kingdom)
2017-01-15
To examine repeatability of parameters derived from non-Gaussian diffusion models in data acquired in children with solid tumours. Paediatric patients (<16 years, n = 17) were scanned twice, 24 h apart, using DWI (6 b-values, 0-1000 mm{sup -2} s) at 1.5 T in a prospective study. Tumour ROIs were drawn (3 slices) and all data fitted using IVIM, stretched exponential, and kurtosis models; percentage coefficients of variation (CV) calculated for each parameter at all ROI histogram centiles, including the medians. The values for ADC, D, DDC{sub α}, α, and DDC{sub K} gave CV < 10 % down to the 5th centile, with sharp CV increases below 5th and above 95th centile. K, f, and D* showed increased CV (>30 %) over the histogram. ADC, D, DDC{sub α}, and DDC{sub K} were strongly correlated (ρ > 0.9), DDC{sub α} and α were not correlated (ρ = 0.083). Perfusion- and kurtosis-related parameters displayed larger, more variable CV across the histogram, indicating observed clinical changes outside of D/DDC in these models should be interpreted with caution. Centiles below 5th for all parameters show high CV and are unreliable as diffusion metrics. The stretched exponential model behaved well for both DDC{sub α} and α, making it a strong candidate for modelling multiple-b-value diffusion imaging data. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Cogollo, Heiner R S; Rodriguez, Yeinzon; Valenzuela-Toledo, Cesar A, E-mail: heiner.sarmiento@ciencias.uis.edu.co, E-mail: yeinzon.rodriguez@uan.edu.co, E-mail: cavalto@ciencias.uis.edu.co [Escuela de Fisica, Universidad Industrial de Santander, Ciudad Universitaria, Bucaramanga (Colombia)
2008-08-15
We show in this paper that it is possible to attain very high, including observable, values for the level of non-Gaussianity f{sub NL} associated with the bispectrum B{sub {zeta}} of the primordial curvature perturbation {zeta}, in a subclass of small-field slow-roll models of inflation with canonical kinetic terms. Such a result is obtained by taking care of loop corrections both in the spectrum P{sub {zeta}} and in the bispectrum B{sub {zeta}}. Sizable values for f{sub NL} arise even if {zeta} is generated during inflation. Five issues are considered when constraining the available parameter space: (1) We must ensure that we are in a perturbative regime so that the {zeta} series expansion, and its truncation, are valid. (2) We must apply the correct condition for the (possible) loop dominance in B{sub {zeta}} and/or P{sub {zeta}}. (3) We must satisfy the spectrum normalization condition. (4) We must satisfy the spectral tilt constraint. (5) We must have enough inflation to solve the horizon problem.
International Nuclear Information System (INIS)
Cogollo, Heiner R S; Rodríguez, Yeinzon; Valenzuela-Toledo, César A
2008-01-01
We show in this paper that it is possible to attain very high, including observable, values for the level of non-Gaussianity f NL associated with the bispectrum B ζ of the primordial curvature perturbation ζ, in a subclass of small-field slow-roll models of inflation with canonical kinetic terms. Such a result is obtained by taking care of loop corrections both in the spectrum P ζ and in the bispectrum B ζ . Sizable values for f NL arise even if ζ is generated during inflation. Five issues are considered when constraining the available parameter space: (1) We must ensure that we are in a perturbative regime so that the ζ series expansion, and its truncation, are valid. (2) We must apply the correct condition for the (possible) loop dominance in B ζ and/or P ζ . (3) We must satisfy the spectrum normalization condition. (4) We must satisfy the spectral tilt constraint. (5) We must have enough inflation to solve the horizon problem
Kim, MinJeong; Liu, Hongbin; Kim, Jeong Tai; Yoo, ChangKyoo
2014-08-15
Sensor faults in metro systems provide incorrect information to indoor air quality (IAQ) ventilation systems, resulting in the miss-operation of ventilation systems and adverse effects on passenger health. In this study, a new sensor validation method is proposed to (1) detect, identify and repair sensor faults and (2) evaluate the influence of sensor reliability on passenger health risk. To address the dynamic non-Gaussianity problem of IAQ data, dynamic independent component analysis (DICA) is used. To detect and identify sensor faults, the DICA-based squared prediction error and sensor validity index are used, respectively. To restore the faults to normal measurements, a DICA-based iterative reconstruction algorithm is proposed. The comprehensive indoor air-quality index (CIAI) that evaluates the influence of the current IAQ on passenger health is then compared using the faulty and reconstructed IAQ data sets. Experimental results from a metro station showed that the DICA-based method can produce an improved IAQ level in the metro station and reduce passenger health risk since it more accurately validates sensor faults than do conventional methods. Copyright © 2014 Elsevier B.V. All rights reserved.
Kartalis, Nikolaos; Manikis, Georgios C; Loizou, Louiza; Albiin, Nils; Zöllner, Frank G; Del Chiaro, Marco; Marias, Kostas; Papanikolaou, Nikolaos
2016-01-01
To compare two Gaussian diffusion-weighted MRI (DWI) models including mono-exponential and bi-exponential, with the non-Gaussian kurtosis model in patients with pancreatic ductal adenocarcinoma. After written informed consent, 15 consecutive patients with pancreatic ductal adenocarcinoma underwent free-breathing DWI (1.5T, b-values: 0, 50, 150, 200, 300, 600 and 1000 s/mm 2 ). Mean values of DWI-derived metrics ADC, D, D*, f, K and D K were calculated from multiple regions of interest in all tumours and non-tumorous parenchyma and compared. Area under the curve was determined for all metrics. Mean ADC and D K showed significant differences between tumours and non-tumorous parenchyma (both P < 0.001). Area under the curve for ADC, D, D*, f, K, and D K were 0.77, 0.52, 0.53, 0.62, 0.42, and 0.84, respectively. ADC and D K could differentiate tumours from non-tumorous parenchyma with the latter showing a higher diagnostic accuracy. Correction for kurtosis effects has the potential to increase the diagnostic accuracy of DWI in patients with pancreatic ductal adenocarcinoma.
Probing the Dusty Stellar Populations of the Local Volume Galaxies with JWST /MIRI
Energy Technology Data Exchange (ETDEWEB)
Jones, Olivia C.; Meixner, Margaret [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD, 21218 (United States); Justtanont, Kay [Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, SE-439 92 Onsala (Sweden); Glasse, Alistair [UK Astronomy Technology Centre, Royal Observatory, Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom)
2017-05-20
The Mid-Infrared Instrument (MIRI) for the James Webb Space Telescope ( JWST ) will revolutionize our understanding of infrared stellar populations in the Local Volume. Using the rich Spitzer -IRS spectroscopic data set and spectral classifications from the Surveying the Agents of Galaxy Evolution (SAGE)–Spectroscopic survey of more than 1000 objects in the Magellanic Clouds, the Grid of Red Supergiant and Asymptotic Giant Branch Star Model (grams), and the grid of YSO models by Robitaille et al., we calculate the expected flux densities and colors in the MIRI broadband filters for prominent infrared stellar populations. We use these fluxes to explore the JWST /MIRI colors and magnitudes for composite stellar population studies of Local Volume galaxies. MIRI color classification schemes are presented; these diagrams provide a powerful means of identifying young stellar objects, evolved stars, and extragalactic background galaxies in Local Volume galaxies with a high degree of confidence. Finally, we examine which filter combinations are best for selecting populations of sources based on their JWST colors.
Shadrack Jabes, B.; Krekeler, C.; Klein, R.; Delle Site, L.
2018-05-01
We employ the Grand Canonical Adaptive Resolution Simulation (GC-AdResS) molecular dynamics technique to test the spatial locality of the 1-ethyl 3-methyl imidazolium chloride liquid. In GC-AdResS, atomistic details are kept only in an open sub-region of the system while the environment is treated at coarse-grained level; thus, if spatial quantities calculated in such a sub-region agree with the equivalent quantities calculated in a full atomistic simulation, then the atomistic degrees of freedom outside the sub-region play a negligible role. The size of the sub-region fixes the degree of spatial locality of a certain quantity. We show that even for sub-regions whose radius corresponds to the size of a few molecules, spatial properties are reasonably reproduced thus suggesting a higher degree of spatial locality, a hypothesis put forward also by other researchers and that seems to play an important role for the characterization of fundamental properties of a large class of ionic liquids.
Energy Technology Data Exchange (ETDEWEB)
Kimura, Hikari; Dynes, Robert; Barber Jr., Richard. P.; Ono, S.; Ando, Y.
2009-09-01
Direct measurements of the superconducting superfluid on the surface of vacuum-cleaved Bi2Sr2CaCu2O8+delta (BSCCO) samples are reported. These measurements are accomplished via Josephson tunneling into the sample using a novel scanning tunneling microscope (STM) equipped with a superconducting tip. The spatial resolution of the STM of lateral distances less than the superconducting coherence length allows it to reveal local inhomogeneities in the pair wavefunction of the BSCCO. Instrument performance is demonstrated first with Josephson measurements of Pb films followed by the layered superconductor NbSe2. The relevant measurement parameter, the Josephson ICRN product, is discussed within the context of both BCS superconductors and the high transition temperature superconductors. The local relationship between the ICRN product and the quasiparticle density of states (DOS) gap are presented within the context of phase diagrams for BSCCO. Excessive current densities can be produced with these measurements and have been found to alter the local DOS in the BSCCO. Systematic studies of this effect were performed to determine the practical measurement limits for these experiments. Alternative methods for preparation of the BSCCO surface are also discussed.
International Nuclear Information System (INIS)
Shiohara, K.; Higashikawa, K.; Kawaguchi, T.; Inoue, M.; Kiss, T.; Yoshizumi, M.; Izumi, T.
2011-01-01
We have investigated 2-dimensional distribution of critical current density. We have measured TFA-MOD processed YBCO coated conductor. We used scanning Hall-probe microscopy. These provided information is useful for fabrication process of coated conductor. We have carried out 2-dimensional (2D) measurement of local critical current in a Trifluoroacetates-Metal Organic Deposition (TFA-MOD) processed YBCO coated conductor using scanning Hall-probe microscopy. Recently, remarkable R and D accomplishments on the fabrication processes of coated conductors have been conducted extensively and reported. The TFA-MOD process has been expected as an attractive process to produce coated conductors with high performance at a low production cost due to a simple process using non-vacuum equipments. On the other hand, enhancement of critical currents and homogenization of the critical current distribution in the coated conductors are definitely very important for practical applications. According to our measurements, we can detect positions and spatial distribution of defects in the conductor. This kind of information will be very helpful for the improvement of the TFA-MOD process and for the design of the conductor intended for practical electric power device applications.
Local work function analysis of Pt/TiO2 photocatalyst by a Kelvin probe force microscope
International Nuclear Information System (INIS)
Hiehata, K; Sasahara, A; Onishi, H
2007-01-01
Nanometre-sized Pt clusters were prepared on a TiO 2 (110)-(1 x 1) surface, and the lateral distribution of work function was examined by using a Kelvin probe force microscope. Local work function on the Pt clusters was smaller than that on the surrounding TiO 2 surface. Assuming that the dipole moments which perturb the work function are produced by uneven electron distribution, the decrease of the work function indicates electron transfer from the clusters to the TiO 2 surface. After decomposition of pivalate anions on the surfaces by UV irradiation, the work function increased on some Pt clusters. It is known that holes photoexcited in TiO 2 attach to pivalate anions to cause a decomposition reaction. Hence the increase of the observed work function by UV irradiation can be ascribed to the trapping of the accompanying electrons to the Pt clusters
International Nuclear Information System (INIS)
Kuca, Petr; Helebrant, Jan; Cespirova, Irena; Judas, Libor; Skala, Lukas
2015-01-01
The results of a security project aimed at the development of a radiation situation monitoring system using optimized probes for dose rate measurements are described. The system is suitable for use at local government sites as well as at other sites. The system includes dose rate measurement probes with the variable configuration functionality (detection part), equipment for data transfer to a central workplace (communication part) and application for collection, storage and administration of the results and their presentation at a website (presentation part). The dosimetric and other operational properties of the probes were tested and the feasibility of their integration into measurement networks using the IMS central application was examined. (orig.)
Probing the parameter space of HD 49933: A comparison between global and local methods
Energy Technology Data Exchange (ETDEWEB)
Creevey, O L [Instituto de Astrofisica de Canarias (IAC), E-38200 La Laguna, Tenerife (Spain); Bazot, M, E-mail: orlagh@iac.es, E-mail: bazot@astro.up.pt [Centro de Astrofisica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal)
2011-01-01
We present two independent methods for studying the global stellar parameter space (mass M, age, chemical composition X{sub 0}, Z{sub 0}) of HD 49933 with seismic data. Using a local minimization and an MCMC algorithm, we obtain consistent results for the determination of the stellar properties: M 1.1-1.2 M{sub sun} Age {approx} 3.0 Gyr, Z{sub 0} {approx} 0.008. A description of the error ellipses can be defined using Singular Value Decomposition techniques, and this is validated by comparing the errors with those from the MCMC method.
Measurement of local two-phase flow parameters of nanofluids using conductivity double-sensor probe.
Park, Yu Sun; Chang, Soon Heung
2011-04-04
A two-phase flow experiment using air and water-based γ-Al2O3 nanofluid was conducted to observe the basic hydraulic phenomenon of nanofluids. The local two-phase flow parameters were measured with a conductivity double-sensor two-phase void meter. The void fraction, interfacial velocity, interfacial area concentration, and mean bubble diameter were evaluated, and all of those results using the nanofluid were compared with the corresponding results for pure water. The void fraction distribution was flattened in the nanofluid case more than it was in the pure water case. The higher interfacial area concentration resulted in a smaller mean bubble diameter in the case of the nanofluid. This was the first attempt to measure the local two-phase flow parameters of nanofluids using a conductivity double-sensor two-phase void meter. Throughout this experimental study, the differences in the internal two-phase flow structure of the nanofluid were identified. In addition, the heat transfer enhancement of the nanofluid can be resulted from the increase of the interfacial area concentration which means the available area of the heat and mass transfer.
International Nuclear Information System (INIS)
Park, S. K.; Cho, B. R.; Park, H. Y.; Ri, H. C.
2011-01-01
Distribution of the local critical temperature and current density in YBCO coated conductors were analyzed using Low-temperature Scanning Laser and Hall Probe Microscopy (LTSLHPM). We prepared YBCO coated conductors of various bridge types to study the spatial distribution of the critical temperature and the current density in single and multi bridges. LTSLHPM system was modified for detailed linescan or two-dimensional scan both scanning laser and scanning Hall probe method simultaneously. We analyzed the local critical temperature of single and multi bridges from series of several linescans of scanning laser microscopy. We also investigated local current density and hysteresis curve of single bridge from experimental results of scanning Hall probe microscopy.
Magnetoresistance Probe of Ultrathin Mn5Ge3 Films with Anderson Weak Localization
International Nuclear Information System (INIS)
Li-Jun, Chen; De-Yong, Wang; Qing-Feng, Zhan; Wei, He; Qing-An, Li
2008-01-01
We present the magnetoresistance measurements of ultrathin Mn 5 Ge 3 films with different thicknesses at low temperatures. Owing to the lattice mismatch between Mn 5 Ge 3 and Ge (111), the thickness of Mn 5 Ge 3 films has a significant effect on the magnetoresistance. When the thickness of Mn is more than 72 monolayers (MLs), the magnetoresistance of the Mn 5 Ge 3 films appears a peak at about 6kOe, which shows that the magnetoresistance results from the Anderson weak localization effect and the variable range hopping in the presence of a magnetic field. The magnetic and semiconducting properties indicate that the Mn 5 Ge 3 film is a potential material for spin injection. (condensed matter: electronic structure, electrical, magnetic, and optical properties)
Energy Technology Data Exchange (ETDEWEB)
Farhang, Amin; Khosroshahi, Habib G.; Javadi, Atefeh [School of Astronomy, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5746, Tehran (Iran, Islamic Republic of); Van Loon, Jacco Th., E-mail: a.farhang@ipm.ir [Astrophysics Group, Lennard-Jones Laboratories, Keele University, Staffordshire ST5 5BG (United Kingdom)
2015-02-01
We present new high signal-to-noise ratio (S/N) observations of the diffuse interstellar bands (DIBs) in the Local Bubble and its surroundings. We observed 432 sightlines and obtain the equivalent widths of the λ5780 and λ5797 Å DIBs up to a distance of ∼200 pc. All of the observations were carried out using the Intermediate Dispersion Spectrograph on the 2.5 m Isaac Newton Telescope, during three years, to reach a minimum S/N of ∼2000. All of the λ5780 and λ5797 absorptions are presented in this paper and we tabulate the observed values of the interstellar parameters, λ5780, λ5797, Na ID{sub 1}, and Na ID{sub 2}, including the uncertainties.
International Nuclear Information System (INIS)
Farhang, Amin; Khosroshahi, Habib G.; Javadi, Atefeh; Van Loon, Jacco Th.
2015-01-01
We present new high signal-to-noise ratio (S/N) observations of the diffuse interstellar bands (DIBs) in the Local Bubble and its surroundings. We observed 432 sightlines and obtain the equivalent widths of the λ5780 and λ5797 Å DIBs up to a distance of ∼200 pc. All of the observations were carried out using the Intermediate Dispersion Spectrograph on the 2.5 m Isaac Newton Telescope, during three years, to reach a minimum S/N of ∼2000. All of the λ5780 and λ5797 absorptions are presented in this paper and we tabulate the observed values of the interstellar parameters, λ5780, λ5797, Na ID 1 , and Na ID 2 , including the uncertainties
Frisenda, Riccardo; Perrin, Mickael L; van der Zant, Herre S J
2015-01-01
We study single-molecule oligo(phenylene ethynylene)dithiol junctions by means of inelastic electron tunneling spectroscopy (IETS). The molecule is contacted with gold nano-electrodes formed with the mechanically controllable break junction technique. We record the IETS spectrum of the molecule from direct current measurements, both as a function of time and electrode separation. We find that for fixed electrode separation the molecule switches between various configurations, which are characterized by different IETS spectra. Similar variations in the IETS signal are observed during atomic rearrangements upon stretching of the molecular junction. Using quantum chemistry calculations, we identity some of the vibrational modes which constitute a chemical fingerprint of the molecule. In addition, changes can be attributed to rearrangements of the local molecular environment, in particular at the molecule-electrode interface. This study shows the importance of taking into account the interaction with the electrodes when describing inelastic contributions to transport through single-molecule junctions.
Farhang, Amin; Khosroshahi, Habib G.; Javadi, Atefeh; van Loon, Jacco Th.
2015-02-01
We present new high signal-to-noise ratio (S/N) observations of the diffuse interstellar bands (DIBs) in the Local Bubble and its surroundings. We observed 432 sightlines and obtain the equivalent widths of the λ5780 and λ5797 Å DIBs up to a distance of ~200 pc. All of the observations were carried out using the Intermediate Dispersion Spectrograph on the 2.5 m Isaac Newton Telescope, during three years, to reach a minimum S/N of ~2000. All of the λ5780 and λ5797 absorptions are presented in this paper and we tabulate the observed values of the interstellar parameters, λ5780, λ5797, Na ID1, and Na ID2, including the uncertainties.
Local probe (170Yb3+) measurements of magnetic fields in YBa2Cu3Ox
International Nuclear Information System (INIS)
Hodges, J.A.; Bonville, P.; Vincent, E.
1989-01-01
We introduce the technique of studying the field dependence of the electro-nuclear energy levels of a rare earth to measure the magnetic field present at the rare earth/yttrium site in YBa 2 Cu 3 O x . Measurements were made by 170 Yb spectroscopy. The hyperfine spectrum of the ground state Kramers doublet for Yb 3+ ions diluted into this matrix is sensitive to fields in the range 100 to 2000G. Flux penetration and trapping at the local site level have been measured in superconducting samples. A molecular field exists on the rare earth site in non superconducting samples suggesting that the ordered Cu2 magnetic moments are intrinsically non colinear
DEFF Research Database (Denmark)
Barreto, Lucas; Perkins, Edward; Johannsen, Jens
2013-01-01
The electronic transport properties of epitaxial monolayer graphene (MLG) and hydrogen-intercalated quasi free-standing bilayer graphene (QFBLG) on SiC(0001) are investigated by micro multi-point probes. Using a probe with 12 contacts, we perform four-point probe measurements with the possibility...
The dynamics of the Local Group as a probe of dark energy and modified gravity
Carlesi, Edoardo; Mota, David F.; Winther, Hans A.
2017-04-01
In this work, we study the dynamics of the Local Group (LG) within the context of cosmological models beyond General Relativity (GR). Using observable kinematic quantities to identify candidate pairs, we build up samples of simulated LG-like objects drawing from f(R), symmetron, Dvali, Gabadadze & Porrati and quintessence N-body simulations together with their Λ cold dark matter (ΛCDM) counterparts featuring the same initial random phase realizations. The variables and intervals used to define LG-like objects are referred to as LG model; different models are used throughout this work and adapted to study their dynamical and kinematic properties. The aim is to determine how well the observed LG dynamics can be reproduced within cosmological theories beyond GR, We compute kinematic properties of samples drawn from alternative theories and ΛCDM and compare them to actual observations of the LG mass, velocity and position. As a consequence of the additional pull, pairwise tangential and radial velocities are enhanced in modified gravity and coupled dark energy with respect to ΛCDM inducing significant changes to the total angular momentum and energy of the LG. For example, in models such as f(R) and the symmetron this increase can be as large as 60 per cent, peaking well outside of the 95 per cent confidence region allowed by the data. This shows how simple considerations about the LG dynamics can lead to clear small-scale observational signatures for alternative scenarios, without the need of expensive high-resolution simulations.
De Quilettes, Dane W.
rational design of materials and is leveraged to deploy chemical passivation techniques to improve the optoelectronic quality of the material, with the ultimate goal of improving photovoltaic power conversion efficiency. Reducing non-radiative recombination in semiconducting materials is a prerequisite for achieving the highest performance in a host of light-emitting and photovoltaic applications. In the first study described herein, we used confocal fluorescence microscopy correlated with scanning electron microscopy to spatially resolve the photoluminescence (PL) decay dynamics from films of nonstoichiometric organic-inorganic perovskites, CH3NH 3PbI3(Cl). The PL intensities and lifetimes varied between different grains in the same film, even for films that exhibited long bulk lifetimes. The grain boundaries were dimmer and exhibited faster non-radiative decay. Energy-dispersive x-ray spectroscopy showed a positive correlation between chlorine concentration and regions of brighter PL, while PL imaging revealed that chemical treatment with pyridine could activate previously dark grains. Next, to better elucidate the sources of these loss pathways, we performed a systematic study using confocal and widefield fluorescence microscopy to deconvolve the contributions from diffusion and non-radiative recombination which lead to the observed image heterogeneity. We showed that, in addition to local variations in non-radiative loss, carriers diffuse anisotropically due to heterogeneous intergrain connectivity. In addition to non-radiative recombination impeding material performance, we also showed that the materials exhibit a range of complex dynamic phenomena under illumination. We used a unique combination of confocal PL microscopy and chemical imaging to correlate the local changes in photophysics with composition in CH3NH 3PbI3 films under illumination. We demonstrated that the photo-induced "brightening" of the perovskite PL can be attributed to an order
Directory of Open Access Journals (Sweden)
Spang Rainer
2009-12-01
Full Text Available Abstract Background The Affymetrix MitoChip v2.0 is an oligonucleotide tiling array for the resequencing of the human mitochondrial (mt genome. For each of 16,569 nucleotide positions of the mt genome it holds two sets of four 25-mer probes each that match the heavy and the light strand of a reference mt genome and vary only at their central position to interrogate all four possible alleles. In addition, the MitoChip v2.0 carries alternative local context probes to account for known mtDNA variants. These probes have been neglected in most studies due to the lack of software for their automated analysis. Results We provide ReseqChip, a free software that automates the process of resequencing mtDNA using multiple local context probes on the MitoChip v2.0. ReseqChip significantly improves base call rate and sequence accuracy. ReseqChip is available at http://code.open-bio.org/svnweb/index.cgi/bioperl/browse/bioperl-live/trunk/Bio/Microarray/Tools/. Conclusions ReseqChip allows for the automated consolidation of base calls from alternative local mt genome context probes. It thereby improves the accuracy of resequencing, while reducing the number of non-called bases.
International Nuclear Information System (INIS)
Ding Chunling; Li Jiahua; Yang Xiaoxue; Xiong Hao; Zhang Duo
2011-01-01
The behavior of two-dimensional (2D) atom localization is explored by monitoring the probe absorption in a microwave-driven four-level atomic medium under the action of two orthogonal standing-wave fields. Because of the position-dependent atom-field interaction, the information about the position of the atom can be obtained via the absorption measurement of the weak probe field. It is found that the localization behavior is significantly improved due to the joint quantum interference induced by the standing-wave and microwave-driven fields. Most importantly, the atom can be localized at a particular position and the maximal probability of finding the atom in one period of the standing-wave fields reaches unity by properly adjusting the system parameters. The proposed scheme may provide a promising way to achieve high-precision and high-resolution 2D atom localization.
Directory of Open Access Journals (Sweden)
A. L. Senyavskiy
2015-01-01
Full Text Available The article analyzes the robustness of the digital demodulator of the signal with the lowest frequency shift keying at a subcarrier frequency with respect to non-Gaussian interference type of atmospheric, industrial noise and interfering frequency -and phase-shift keyed signals. This type of demodulator is used for the transmission of navigation data in the systems of air traffic control with automatic dependent surveillance.
TOMS/Earth Probe UV-B Erythemal Local Noon Irradiance Monthly L3 Global 1x1.25 deg Lat/Lon Grid V008
National Aeronautics and Space Administration — This data product contains TOMS/Earth Probe UV-B Erythemal Local Noon Irradiance Monthly L3 Global 1x1.25 deg Lat/Lon Grid Version 8 data in ASCII format. (The...
International Nuclear Information System (INIS)
Fujiwara, Ikuya; Nagata, Hiroaki; Takaki, Wataru
2016-01-01
Prior to surgery for clinically node-negative breast cancer, we diagnosed metastases on the basis of permanent sections and sentinel lymph node biopsy (SNB) using the combined radio isotope (RI)/blue dye method with a hand-type gamma probe under ambulatory local anesthesia. SNB was performed for 99 patients with 103 lesions, including 4 patients with bilateral breast cancer. We achieved an identification rate of 100%, in which the identification pattern included detection by RI and blue-dye in 65 patients (63.1%), detection by RI alone in 37 patients (35.9%), and blue-dye alone in one patient (1.0%). Sentinel lymph node metastasis was macrometastasis in 21 patients (20.4%), micrometastasis in 8 patients (7.8%), and isolated tumor cells in patients (4.9%). In the 80 patients who did not undergo post-SNB axillary lymph node dissection, the median observation period was 33 months and there were no recurrences in the axillary lymph nodes observed. Although the present procedure requires two surgeries, it is a useful method that enables metastasis detection and highly accurate SNB. (author)
Phase structure of the Born-Infeld-anti-de Sitter black holes probed by non-local observables
Energy Technology Data Exchange (ETDEWEB)
Zeng, Xiao-Xiong [Chongqing Jiaotong University, School of Material Science and Engineering, Chongqing (China); Chinese Academy of Sciences, Institute of Theoretical Physics, Beijing (China); Liu, Xian-Ming [Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, MA (United States); Hubei University for Nationalities, Center for Theoretical Physics, School of Sciences, Enshi, Hubei (China); Li, Li-Fang [Chinese Academy of Sciences, State Key Laboratory of Space Weather, Center for Space Science and Applied Research, Beijing (China)
2016-11-15
With the non-local observables such as two point correlation function and holographic entanglement entropy, we probe the phase structure of the Born-Infeld-anti-de Sitter black holes. For the case bQ > 0.5, where b is the Born-Infeld parameter and Q is the charge of the black hole, the phase structure is found to be similar to that of the Van der Waals phase transition, namely the black hole undergoes a first order phase transition and a second order phase transition before it reaches a stable phase. While for the case bQ < 0.5, a new phase branch emerges besides the Van der Waals phase transition. For the first order phase transition, the equal area law is checked, and for the second order phase transition, the critical exponent of the heat capacity is obtained. All these results are found to be the same as that observed in the entropy-temperature plane. (orig.)
Colloidal probe dynamics in gelatin solution during the sol-gel transition.
Hong, Wei; Xu, Guozhi; Ou, Xiaogang; Sun, Weixiang; Wang, Tao; Tong, Zhen
2018-05-16
The dynamics of the colloidal probes in a gelatin solution during the time-dependent sol-gel transition was investigated by multi-particle tracking. The relationship between the relaxation of the medium at the critical gel point and the mean square displacement of the probes was elucidated. Based on this understanding, the critical gel point of gelatin and the corresponding critical exponent n were unambiguously determined by the loss angle criterion and the time-cure superposition. The shift factors of the latter are further used to estimate the time/length-scale evolution of the gelatin during the sol-gel transition. The growth of the medium length scale crossed with the two measuring length scales successively at the pre-gel regime. Coinciding with the length-scale crossovers, the probability density function (PDF) of the probe displacements displayed two transient peaks of non-Gaussianity. In the post-gel regime, the third peak of Gaussianity suggested inhomogeneity in the gel network. The non-Gaussianity results from the bifurcation of diffusivity. The present work showed that the non-Gaussian dynamics of the probes are not the direct equivalence of that of the medium, but an effect of length-scale coupling.
DEFF Research Database (Denmark)
Ørngreen, Rikke; Jørgensen, Anna Neustrup; Noesgaard, Signe Schack
2016-01-01
A project investigating the effectiveness of a collection of online resources for teachers' professional development used mobile probes as a data collection method. Teachers received questions and tasks on their mobile in a dialogic manner while in their everyday context as opposed...... to in an interview. This method provided valuable insight into the contextual use, i.e. how did the online resource transfer to the work practice. However, the research team also found that mobile probes may provide the scaffolding necessary for individual and peer learning at a very local (intra-school) community...... level. This paper is an initial investigation of how the mobile probes process proved to engage teachers in their efforts to improve teaching. It also highlights some of the barriers emerging when applying mobile probes as a scaffold for learning....
Local pH Monitoring of Small Cluster of Cells using a Fiber-Optic Dual-Core Micro-Probe.
Chen, Sisi; Yang, Qingbo; Xiao, Hai; Shi, Honglan; Ma, Yinfa
2017-03-31
Biological studies of tissues and cells have enabled numerous discoveries, but these studies still bear potential risks of invalidation because of cell heterogeneity. Through high-accuracy techniques, recent studies have demonstrated that discrepancies do exist between the results from low-number-cell studies and cell-population-based results. Thus the urgent need to re-evaluate key principles on limited number of cells has been provoked. In this study, a novel designed dual-core fiber-optic pH micro-probe was fabricated and demonstrated for niche environment pH sensing with high spatial resolution. An organic-modified silicate (OrMoSils) sol-gel thin layer was functionalized by entrapping a pH indicator, 2', 7'-Bis (2-carbonylethyl)-5(6)-carboxyfluorescein (BCECF), on a ~70 μm sized probe tip. Good linear correlation between fluorescence ratio of I 560 nm /I 640 nm and intercellular pH values was obtained within a biological-relevant pH range from 6.20 to 7.92 (R 2 = 0.9834), and with a pH resolution of 0.035 ± 0.005 pH units. The probe's horizontal spatial resolution was demonstrated to be less than 2mm. Moreover, the probe was evaluated by measuring the localized extracellular pH changes of cultured human lung cancer cells (A549) when exposed to titanium dioxide nanoparticles (TiO 2 NPs). Results showed that the probe has superior capability for fast, local, and continual monitoring of a small cluster of cells, which provides researchers a fast and accurate technique to conduct local pH measurements for cell heterogeneity-related studies.
Directory of Open Access Journals (Sweden)
Shanfang Huang
2018-01-01
Full Text Available Multiphase flow measurements have become increasingly important in a wide range of industrial fields. In the present study, a dual needle-contact capacitance probe was newly designed to measure local void fractions and bubble velocity in a vertical channel, which was verified by digital high-speed camera system. The theoretical analyses and experiments show that the needle-contact capacitance probe can reliably measure void fractions with the readings almost independent of temperature and salinity for the experimental conditions. In addition, the trigger-level method was chosen as the signal processing method for the void fraction measurement, with a minimum relative error of −4.59%. The bubble velocity was accurately measured within a relative error of 10%. Meanwhile, dynamic response of the dual needle-contact capacitance probe was analyzed in detail. The probe was then used to obtain raw signals for vertical pipe flow regimes, including plug flow, slug flow, churn flow, and bubbly flow. Further experiments indicate that the time series of the output signals vary as the different flow regimes and are consistent with each flow structure.
Probing the local nature of excitons and plasmons in few-layer MoS_{2 }
DEFF Research Database (Denmark)
Nerl, Hannah Catherine; Winther, Kirsten Trøstrup; Hage, Fredrik S.
2017-01-01
Excitons and plasmons are the two most fundamental types of collectiveelectronic excitations occurring in solids. Traditionally, they have beenstudied separately using bulk techniques that probe their average energeticstructure over large spatial regions. However, as the dimensions of materialsan...... excitations that open new possibilities for studyingphoto-absorption and energy transfer processes on a nanometer scale....
International Nuclear Information System (INIS)
Asakura, N.; Tsuji-Iio, S.; Ikeda, Y.; Neyatani, Y.; Seki, M.
1995-01-01
A fast reciprocating probe system with a long drive shaft was incorporated into a multi-junction lower hybrid (LH) wave launcher on JT-60U in order to investigate an improved coupling mechanism of the radio frequency wave to the core plasma. The system has been operated reliably over a horizontal scan of 25 cm in 1.5 s using a compact pneumatic cylinder drive and springs. A double probe measurement provided the scrape-off layer plasma profile between the last closed flux surface and the first wall with the spatial resolution of 1-2 mm measured with a laser displacement gauge. The profiles of the electron density n e and temperature T e were in good agreement with those obtained with a triple probe method. During the LH wave injection with good coupling to the core plasma, an increase in the local T e was observed in front of the LH launcher mouth. The local n e was (7-10)x10 16 m -3 , consistent values needed for the good coupling. copyright 1995 American Institute of Physics
International Nuclear Information System (INIS)
Soh, Wee Tee; Ong, C. K.; Peng, Bin
2015-01-01
We demonstrate the localized excitation and dc electrical detection of magnetostatic surface spin waves (MSSWs) in yttrium iron garnet (YIG) by a shorted coaxial probe. Thin films of NiFe and Pt are patterned at different regions onto a common bulk YIG substrate. A shorted coaxial probe is used to excite spin precession locally near various patterned regions. The dc voltages across the corresponding regions are recorded. For excitation of the Pt regions, the dc voltage spectra are dominated by the spin pumping of MSSWs from YIG, where various modes can be clearly distinguished. For the NiFe region, it is also found that spin pumping from MSSWs generated in YIG dominated the spectra, indicating that the spin pumped currents are dissipated into charge currents via the inverse Spin Hall effect (ISHE) in NiFe. For all regions, dc signals from YIG MSSWs are observed to be much stronger than the ferromagnetic resonance (FMR) uniform mode, likely due to the nature of the microwave excitation. The results indicate the potential of this probe for microwave imaging via dc detection of spin dynamics in continuous and patterned films
International Nuclear Information System (INIS)
Laurent, Ph; Mathieu, J-P; Mattivi, B; Fagnard, J-F; Meslin, S; Noudem, J G; Ausloos, M; Cloots, R; Vanderbemden, Ph
2005-01-01
The aim of this report is to compare the trapped field distribution under a local heating created at the sample edge for different sample morphologies. Hall probe mappings of the magnetic induction trapped in YBCO bulk samples maintained out of thermal equilibrium were performed on YBCO bulk single domains, YBCO single domains with regularly spaced hole arrays, and YBCO superconducting foams. The capability of heat draining was quantified by two criteria: the average induction decay and the size of the thermally affected zone caused by a local heating of the sample. Among the three investigated sample shapes, the drilled single domain displays a trapped induction which is weakly affected by the local heating while displaying a high trapped field. Finally, a simple numerical modelling of the heat flux spreading into a drilled sample is used to suggest some design rules about the hole configuration and their size
International Nuclear Information System (INIS)
Lawton, J J; Pulisciano, A; Palmer, R E
2009-01-01
Secondary-electron emission (SEE) spectra have been obtained with the Scanning Probe Energy Loss Spectrometer at a tip-sample distance of only 50 nm. Such short working distances are required for the best theoretical spatial resolution (<10 nm). The SEE spectra of graphite, obtained as a function of tip bias voltage, are shown to correspond to unoccupied states in the electronic band structure. The SEE spectra of thin gold films demonstrate the capability of identifying (carbonaceous) surface contamination with this technique.
Energy Technology Data Exchange (ETDEWEB)
Lawton, J J; Pulisciano, A; Palmer, R E, E-mail: R.E.Palmer@bham.ac.u [Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT (United Kingdom)
2009-11-25
Secondary-electron emission (SEE) spectra have been obtained with the Scanning Probe Energy Loss Spectrometer at a tip-sample distance of only 50 nm. Such short working distances are required for the best theoretical spatial resolution (<10 nm). The SEE spectra of graphite, obtained as a function of tip bias voltage, are shown to correspond to unoccupied states in the electronic band structure. The SEE spectra of thin gold films demonstrate the capability of identifying (carbonaceous) surface contamination with this technique.
International Nuclear Information System (INIS)
Chiva, S.; Julia, E.; Hernandez, L.; Mendez, S.; Munoz-Cobo, J.L.
2007-01-01
An upward isothermal co-current air-water flow in a vertical pipe (50.2 mm inner diameter) has been experimental investigated. Local measurements of void fraction, interfacial area concentration (IAC), and interfacial velocity and Sauter mean diameter were measured using a double sensor conductivity probe. Liquid velocity and turbulence intensity were measured using laser Doppler anemometry. Different air-water flow configurations was investigated for a liquid flow rate ranged from 0.29 m/s to 2 m/s and a void fraction up to 15%. For each two-phase flow configuration 15 radial position and three axial positions was measured by the conductivity probe methodology, and several radial profiles was measured with LDA at different axial positions. Two theoretical calibration factors have been defined to relate the mean measurable parameter to the interfacial area concentrations obtained and the measured bubbles, including the missed bubbles. Those factors include the effects of bubble motions, and probe spacing. These calibration factors were obtained through new analytical and numerical method, using a Monte Carlo approach. (author)
Lee, Ki Ha; Becker, Alex; Faybishenko, Boris A.; Solbau, Ray D.
2003-10-21
A miniaturized electrical resistivity (ER) probe based on a known current-voltage (I-V) electrode structure, the Wenner array, is designed for local (point) measurement. A pair of voltage measuring electrodes are positioned between a pair of current carrying electrodes. The electrodes are typically about 1 cm long, separated by 1 cm, so the probe is only about 1 inch long. The electrodes are mounted to a rigid tube with electrical wires in the tube and a sand bag may be placed around the electrodes to protect the electrodes. The probes can be positioned in a borehole or on the surface. The electrodes make contact with the surrounding medium. In a dual mode system, individual probes of a plurality of spaced probes can be used to measure local resistance, i.e. point measurements, but the system can select different probes to make interval measurements between probes and between boreholes.
Meroni, Davide; Maglioli, Camilla Carpano; Bovio, Dario; Greco, Francesco G; Aliverti, Andrea
2017-07-01
Electrical Impedance Tomography (EIT) is an image reconstruction technique applied in medicine for the electrical imaging of living tissues. In literature there is the evidence that a large resistivity variation related to the differences of the human tissues exists. As a result of this interest for the electrical characterization of the biological samples, recently the attention is also focused on the identification and characterization of the human tissue, by studying the homogeneity of its structure. An 8 electrodes needle-probe device has been developed with the intent of identifying the structural inhomogeneities under the surface layers. Ex-vivo impeditivity measurements, by placing the needle-probe in 5 different patterns of fat and lean porcine tissue, were performed, and impeditivity maps were obtained by EIDORS open source software for image reconstruction in electrical impedance. The values composing the maps have been analyzed, pointing out a good tissue discrimination, and the conformity with the real images. We conclude that this device is able to perform impeditivity maps matching to reality for position and orientation. In all the five patterns presented is possible to identify and replicate correctly the heterogeneous tissue under test. This new procedure can be helpful to the medical staff to completely characterize the biological sample, in different unclear situations.
International Nuclear Information System (INIS)
Vaast-Paci, Ch.
1997-01-01
This thesis is concerned with the measurement of the local induction in the anisotropic type II superconductor YBa 2 Cu 3 O 7-δ in presence of an applied field. In this compound, the field penetrates in the form of vortices whose characteristics are governed by both intrinsic (critical fields, anisotropy, penetration lengths,...) and extrinsic parameters (such as pinning centers). We have developed a new microscopic technique to measure the local fields using Moessbauer probes 170 Yb 3+ dilutes for Y 3+ . The measurements are based on the field dependence (size and direction) of the Moessbauer transitions between the electronuclear levels of the probe. These probes are distributed randomly over the sample so the measurements provide both the size and the direction of the internal field distribution over the whole sample. The possible measurement range extends from below 50 Oe to about 4000 Oe, for temperatures up to 60 deg.K. Measurements were made at T4.2 deg. K, for sintered pellets with different oxygen amount and for optimally doped ci-axis oriented single crystals. The penetration length measurements showed that the density of the superconducting condensate increases progressively with carrier doping. Field penetration measurements furnished the microscopic lower penetration field H cl , and enabled us to propose a model describing the profile of the flux distribution which is controlled by the pinning centers. The measurements also evidenced an anomalous penetration in small sized single crystals. In additions, we obtained the average direction of the vortices when the applied field is titled from the c axis and we showed that the vortex direction depends on the way the field is applied (ZFC or FC configuration) and that there exists a competition between the pinning forces and the intrinsic anisotropy. (author)
DEFF Research Database (Denmark)
Duvaa, Uffe; Ørngreen, Rikke; Weinkouff Mathiasen, Anne-Gitte
2013-01-01
Mobile probing is a method, developed for learning about digital work situations, as an approach to discover new grounds. The method can be used when there is a need to know more about users and their work with certain tasks, but where users at the same time are distributed (in time and space......). Mobile probing was inspired by the cultural probe method, and was influenced by qualitative interview and inquiry approaches. The method has been used in two subsequent projects, involving school children (young adults at 15-17 years old) and employees (adults) in a consultancy company. Findings point...... to mobile probing being a flexible method for uncovering the unknowns, as a way of getting rich data to the analysis and design phases. On the other hand it is difficult to engage users to give in depth explanations, which seem easier in synchronous dialogs (whether online or face2face). The development...
DEFF Research Database (Denmark)
Duvaa, Uffe; Ørngreen, Rikke; Weinkouff, Anne-Gitte
2012-01-01
Mobile probing is a method, which has been developed for learning about digital work situations, as an approach to discover new grounds. The method can be used when there is a need to know more about users and their work with certain tasks, but where users at the same time are distributed (in time...... and space). Mobile probing was inspired by the cultural probe method, and was influenced by qualitative interview and inquiry approaches. The method has been used in two subsequent projects, involving school children (young adults at 15-17 years old) and employees (adults) in a consultancy company. Findings...... point to mobile probing being a flexible method for uncovering the unknowns, as a way of getting rich data to the analysis and design phases. On the other hand it is difficult to engage users to give in depth explanations, which seem easier in synchronous dialogs (whether online or face2face...
Yamagami, Kohei; Fujiwara, Hidenori; Imada, Shin; Kadono, Toshiharu; Yamanaka, Keisuke; Muro, Takayuki; Tanaka, Arata; Itai, Takuma; Yoshinari, Nobuto; Konno, Takumi; Sekiyama, Akira
2017-07-01
We have examined the local 3d electronic structures of Co-Au multinuclear complexes with the medicinal molecules d-penicillaminate (d-pen) [Co{Au(PPh3)(d-pen)}2]ClO4 and [Co3{Au3(tdme)(d-pen)3}2] by Co L2,3-edge soft X-ray absorption (XAS) spectroscopy, where PPh3 denotes triphenylphosphine and tdme stands for 1,1,1-tris[(diphenylphosphino)methyl]ethane. The Co L2,3-edge XAS spectra indicate the localized ionic 3d electronic states in both materials. The experimental spectra are well explained by spectral simulation for a localized Co ion under ligand fields with the full multiplet theory, which verifies that the ions are in the low-spin Co3+ state in the former compound and in the high-spin Co2+ state in the latter.
Förster-type energy transfer as a probe for changes in local fluctuations of the protein matrix.
Somogyi, B; Matkó, J; Papp, S; Hevessy, J; Welch, G R; Damjanovich, S
1984-07-17
Much evidence, on both theoretical and experimental sides, indicates the importance of local fluctuations (in energy levels, conformational substates, etc.) of the macromolecular matrix in the biological activity of proteins. We describe here a novel application of the Förster-type energy-transfer process capable of monitoring changes both in local fluctuations and in conformational states of macromolecules. A new energy-transfer parameter, f, is defined as an average transfer efficiency, [E], normalized by the actual average quantum efficiency of the donor fluorescence, [phi D]. A simple oscillator model (for a one donor-one acceptor system) is presented to show the sensitivity of this parameter to changes in amplitudes of local fluctuations. The different modes of averaging (static, dynamic, and intermediate cases) occurring for a given value of the average transfer rate, [kt], and the experimental requirements as well as limitations of the method are also discussed. The experimental tests were performed on the ribonuclease T1-pyridoxamine 5'-phosphate conjugate (a one donor-one acceptor system) by studying the change of the f parameter with temperature, an environmental parameter expectedly perturbing local fluctuations of proteins. The parameter f increased with increasing temperature as expected on the basis of the oscillator model, suggesting that it really reflects changes of fluctuation amplitudes (significant changes in the orientation factor, k2, as well as in the spectral properties of the fluorophores can be excluded by anisotropy measurements and spectral investigations). Possibilities of the general applicability of the method are also discussed.
Magnetic resonance as a local probe for linear bands in the Weyl semimetals NbP and TaP
Energy Technology Data Exchange (ETDEWEB)
Baenitz, Michael; Yasuoka, Hiroshi; Majumder, Mayukh; Shekhar, Chandra; Yan, Binghai; Felser, Claudia; Schmidt, Marcus [MPI for Chemical Physics of Solids, Dresden (Germany)
2016-07-01
Some compensated d-electron semimetals, for example the monophosphites NbP and TaP, with non centrosymmetric structure and with sizable spin orbit coupling (SOC) form a new class of material: the Weyl semimetals (WSM). A unique linear crossing of valence- and conduction- band in a single point in reciprocal space defines the so called Weyl point where the fermion mass vanishes theoretically. In real materials the Fermi level E{sub F} does not exactly match the Weyl node and as a consequence residual very light fermions are found. Due to the SOC these Weyl fermions have a chirality (handedness) on their linear dispersive (E ∝k) bands and frequently a linear density of states (DOS) at the Fermi level E{sub F}. We use NMR as a probe for this linear d- electron bands. The shift provides the s- and d- electron contributions to the DOS at E{sub F}, whereas the spin lattice relaxation is governed by low energy excitations around E{sub F}. {sup 31}P (I = 1/2) - Fourier - transform - and {sup 95}Nb (I = 9/2) - broadline - sweep - NMR studies are performed. We investigated powder samples as well as single crystals on both systems. The angular dependence of the {sup 95}Nb- and {sup 31}P - NMR lines is discussed.
International Nuclear Information System (INIS)
Barba, D; Martin, F; Ross, G G
2008-01-01
Silicon nanocrystals (Si-nc) and amorphous silicon (α-Si) produced by silicon implantation in fused silica have been studied by micro-Raman spectroscopy. Information regarding the Raman signature of the α-Si phonon excitation was extracted from Raman depth-probing measurements using the phenomenological phonon confinement model. The spectral deconvolution of the Raman measurements recorded at different laser focusing depths takes into account both the Si-nc size variation and the Si-nc spatial distribution within the sample. The phonon peak associated with α-Si around 470 cm -1 is greatest for in-sample laser focusing, indicating that the formation of amorphous silicon is more important in the region containing a high concentration of silicon excess, where large Si-nc are located. As also observed for Si-nc systems prepared by SiO x layer deposition, this result demonstrates the presence of α-Si in high excess Si implanted Si-nc systems
Radutoiu, Nicoleta; Alexis, Joël; Lacroix, Loïc; Abrudeanu, Marioara; Petit, Jacques-Alain
2013-01-01
International audience; The 2xxx serie aluminum alloys are characterized by good mechanical performances and low density, however they are susceptible to different forms of localized corrosion: pitting corrosion, intergranular corrosion and stress corrosion cracking. The 2024-T351 aluminum alloy is used in the aircraft industry for numerous applications such as fuselage and door skin. Corrosion damage of the material is also very detrimental for the structural integrity of the aircraft. The p...
Radutoiu , Nicoleta; Lacroix , Loïc; Alexis , Joël; Abrudeanu , Marioara; Petit , Jacques-Alain
2012-01-01
International audience; The 2xxx serie aluminum alloys are characterized by good mechanical performances and low density, however they are susceptible to different forms of localized corrosion: pitting corrosion, intergranular corrosion and stress corrosion cracking. The 2024-T351 aluminum alloy is used in the aircraft industry for numerous applications such as fuselage and door skin. Corrosion damage of the material is also very detrimental for the structural integrity of the aircraft. The p...
Nonaka, Kouichi; Ohata, Ken; Ban, Shinichi; Ichihara, Shin; Takasugi, Rumi; Minato, Yohei; Tashima, Tomoaki; Matsuyama, Yasushi; Takita, Maiko; Matsuhashi, Nobuyuki; Neumann, Helmut
2015-12-16
Probe-based confocal laser endomicroscopy (pCLE) is capable of acquiring in vivo magnified cross-section images of the gastric mucosa. Intravenous injection of fluorescein sodium is used for confocal imaging. However, it is still under debate if local administration of the dye to the mucosa is also effective for confocal imaging as it is not yet clear if topical application also reveals the intramucosal distribution of fluorescein. The objective of this study was to evaluate the intramucosal distribution of fluorescein sodium after topical application and to compare the distribution to the conventional intravenous injection used for confocal imaging. pCLE of the stomach uninfected with Helicobacter pylori was performed in a healthy male employing intravenous administration and local mucosal application of fluorescein. The mucosa of the lower gastric body was biopsied 1 min and 5 min after intravenous administration or local mucosal application of fluorescein, and the distribution of fluorescein in the biopsy samples was examined histologically. Green fluorescence was already observed in the cytoplasm of fundic glandular cells in the biopsied deep mucosa 1 min after local mucosal application of fluorescein. It was also observed in the foveolar lumen and inter-foveolar lamina propria, although it was noted at only a few sites. In the tissue biopsied 5 min after the local mucosal application of fluorescein, green fluorescence was more frequently noted in the cytoplasm of fundic glandular cells than in that 1 min after the local mucosal application of fluorescein, although obvious green fluorescence was not identified in the foveolar lumen or inter-foveolar lamina propria. The distribution of intravenously administered fluorescein in the cytoplasm of fundic glandular cells was also clearly observed similarly to that after local mucosal application of fluorescein. Green fluorescence in more cells was observed in many cells 5 min after intravenous administration compared
Oresic Bender, Kristina; Ofori, Leslie; van der Linden, Wouter A; Mock, Elliot D; Datta, Gopal K; Chowdhury, Somenath; Li, Hao; Segal, Ehud; Sanchez Lopez, Mateo; Ellman, Jonathan A; Figdor, Carl G; Bogyo, Matthew; Verdoes, Martijn
2015-04-15
The cysteine cathepsins are a group of 11 proteases whose function was originally believed to be the degradation of endocytosed material with a high degree of redundancy. However, it has become clear that these enzymes are also important regulators of both health and disease. Thus, selective tools that can discriminate between members of this highly related class of enzymes will be critical to further delineate the unique biological functions of individual cathepsins. Here we present the design and synthesis of a near-infrared quenched activity-based probe (qABP) that selectively targets cathepsin S which is highly expressed in immune cells. Importantly, this high degree of selectivity is retained both in vitro and in vivo. In combination with a new green-fluorescent pan-reactive cysteine cathepsin qABP we performed dual color labeling studies in bone marrow-derived immune cells and identified vesicles containing exclusively cathepsin S activity. This observation demonstrates the value of our complementary cathepsin probes and provides evidence for the existence of specific localization of cathepsin S activity in dendritic cells.
Directory of Open Access Journals (Sweden)
Graham Cormode
Full Text Available Many modern applications of AI such as web search, mobile browsing, image processing, and natural language processing rely on finding similar items from a large database of complex objects. Due to the very large scale of data involved (e.g., users' queries from commercial search engines, computing such near or nearest neighbors is a non-trivial task, as the computational cost grows significantly with the number of items. To address this challenge, we adopt Locality Sensitive Hashing (a.k.a, LSH methods and evaluate four variants in a distributed computing environment (specifically, Hadoop. We identify several optimizations which improve performance, suitable for deployment in very large scale settings. The experimental results demonstrate our variants of LSH achieve the robust performance with better recall compared with "vanilla" LSH, even when using the same amount of space.
Directory of Open Access Journals (Sweden)
Dominika Żurek-Biesiada
2016-06-01
Full Text Available Single Molecule Localization Microscopy (SMLM is a recently emerged optical imaging method that was shown to achieve a resolution in the order of tens of nanometers in intact cells. Novel high resolution imaging methods might be crucial for understanding of how the chromatin, a complex of DNA and proteins, is arranged in the eukaryotic cell nucleus. Such an approach utilizing switching of a fluorescent, DNA-binding dye Vybrant® DyeCycle™ Violet has been previously demonstrated by us (Żurek-Biesiada et al., 2015 [1]. Here we provide quantitative information on the influence of the chemical environment on the behavior of the dye, discuss the variability in the DNA-associated signal density, and demonstrate direct proof of enhanced structural resolution. Furthermore, we compare different visualization approaches. Finally, we describe various opportunities of multicolor DNA/SMLM imaging in eukaryotic cell nuclei.
International Nuclear Information System (INIS)
Del Ben, Mauro; Hutter, Jürg; VandeVondele, Joost
2015-01-01
Water is a ubiquitous liquid that displays a wide range of anomalous properties and has a delicate structure that challenges experiment and simulation alike. The various intermolecular interactions that play an important role, such as repulsion, polarization, hydrogen bonding, and van der Waals interactions, are often difficult to reproduce faithfully in atomistic models. Here, electronic structure theories including all these interactions at equal footing, which requires the inclusion of non-local electron correlation, are used to describe structure and dynamics of bulk liquid water. Isobaric-isothermal (NpT) ensemble simulations based on the Random Phase Approximation (RPA) yield excellent density (0.994 g/ml) and fair radial distribution functions, while various other density functional approximations produce scattered results (0.8-1.2 g/ml). Molecular dynamics simulation in the microcanonical (NVE) ensemble based on Møller-Plesset perturbation theory (MP2) yields dynamical properties in the condensed phase, namely, the infrared spectrum and diffusion constant. At the MP2 and RPA levels of theory, ice is correctly predicted to float on water, resolving one of the anomalies as resulting from a delicate balance between van der Waals and hydrogen bonding interactions. For several properties, obtaining quantitative agreement with experiment requires correction for nuclear quantum effects (NQEs), highlighting their importance, for structure, dynamics, and electronic properties. A computed NQE shift of 0.6 eV for the band gap and absorption spectrum illustrates the latter. Giving access to both structure and dynamics of condensed phase systems, non-local electron correlation will increasingly be used to study systems where weak interactions are of paramount importance
Enhancing local absorption within a gold nano-sphere on a dielectric surface under an AFM probe
International Nuclear Information System (INIS)
Talebi Moghaddam, Sina; Ertürk, Hakan; Mengüç, M. Pınar
2016-01-01
This study considers enhancing localized absorption by a gold nanoparticle (NP) placed over a substrate where an atomic force microscope (AFM) tip is in close proximity of the particle. The gold NP and AFM tip are interacting with a surface evanescent wave, resulting a near-field coupling between the tip and NP and consequently enhances the absorption. This concept can be used for selective heating of NPs placed over a surface that enables precise manufacturing at nanometer scales. Different tip positions are considered to identify the optimal tip location and the corresponding enhancement limits. The effects of these interactions on the absorption profiles of dielectric core/gold shell NPs are also studied. It is observed that using core–shell nanoparticles with a dielectric core leads to further enhancement of the absorption efficiency and a more uniform distribution of absorption over the shell. Discrete dipole approximation coupled with surface interactions (DDA-SI) is employed throughout the study, and it is vectorized to improve its computational efficiency. - Highlights: • Plasmonic coupling between solid or core-shell nanoparticles, dielectric surface and Si AFM tip is investigated for achieving localized heating for nano-manufacturing. • Absorption efficiency enhancement limits for core-shell and solid nanoparticles are identified using an AFM tip for surface evanescent wave heating. • The effect of tip location, relative to surface wave direction is outlined, identifying optimal locations, and heat absorption distribution over core-shell and solid nanoparticles. • While using a Si AFM tip enhances absorption, using a dielectric core result in further enhancement in absorption with a more uniform distribution. • DDA-SI-v developed by vectorizing the formulations of DDA-SI for improved computational efficiency.
Zargar, Behrooz; Hatamie, Amir
2013-04-01
Isoniazid is an important antibiotic, which is widely used to treat tuberculosis. This study presents a colorimetric method for the determination of Isoniazid based on localized surface plasmon resonance (LSPR) property of gold nanoparticles. An LSPR band is produced by reducing gold ions in solution using Isoniazid as the reducing agent. Influences of the following relevant variables were examined and optimized in the experiment, formation time of gold nanoparticles, pH, buffer and stabilizer. These tests demonstrated that under optimum conditions the absorbance of Au nanoparticles at 530 nm related linearly to the concentration of Isoniazid in the range of 1.0-8.0 μg mL-1 with a detection limit of 0.98 μg mL-1. This colorimetric method has been successfully applied to the determine Isoniazid in tablets and spiked serum samples. The proposed colorimetric assay exhibits good reproducibility and accuracy, providing a simple and rapid method for analysis of Isoniazid.
International Nuclear Information System (INIS)
Ljungberg, Peter; Malmsten, Yvonne; Axner, Ove
1995-01-01
The lifetimes of atomic metastable states in an acetylene/air flame have been investigated using the laser-enhanced ionization technique. The lifetimes were found to be several orders of magnitude less than the natural ones, which clearly shows that they are fully determined by the surrounding environment. The lifetime of a specific state has been investigated as a function of flame conditions. It was found that the lifetime is strongly dependent on the local flame composition, with a distinct maximum for stoichiometric conditions. For fuel-lean local conditions, the excess of O2 acts as an effective quencher of the metastable state, while for fuel-rich conditions the quenching is dominated by unburned fuel components. An acetylene/air flame has been probed both as a function of height in the flame, as well as a function of fuel/air composition fed to the burner. The experiments show clearly for which heights and fuel/air compositions that lean, stoichiometric or rich conditions prevail. This makes a monitoring of metastable state lifetimes a useful technique for combustion analysis
Directory of Open Access Journals (Sweden)
Xiaobin Hong
2015-01-01
Full Text Available Direct Current (DC electrical resistivity is a material property that is sensitive to temperature changes. In this paper, the relationship between resistivity and local temperature inside steel shell battery cells (two commercial 10 Ah and 4.5 Ah lithium-ion cells is innovatively studied by Electrical Resistance Tomography (ERT. The Schlumberger configuration in ERT is applied to divide the cell body into several blocks distributed in different levels, where the apparent resistivities are measured by multi-electrode surface probes. The investigated temperature ranges from −20 to 80 °C. Experimental results have shown that the resistivities mainly depend on temperature changes in each block of the two cells used and the function of the resistivity and temperature can be fitted to the ERT-measurement results in the logistical-plot. Subsequently, the dependence of resistivity on the state of charge (SOC is investigated, and the SOC range of 70%–100% has a remarkable impact on the resistivity at low temperatures. The proposed approach under a thermal cool down regime is demonstrated to monitor the local transient temperature.
Stuhlmüller, M.; Schwarz-Finsterle, J.; Fey, E.; Lux, J.; Bach, M.; Cremer, C.; Hinderhofer, K.; Hausmann, M.; Hildenbrand, G.
2015-10-01
Trinucleotide repeat expansions (like (CGG)n) of chromatin in the genome of cell nuclei can cause neurological disorders such as for example the Fragile-X syndrome. Until now the mechanisms are not clearly understood as to how these expansions develop during cell proliferation. Therefore in situ investigations of chromatin structures on the nanoscale are required to better understand supra-molecular mechanisms on the single cell level. By super-resolution localization microscopy (Spectral Position Determination Microscopy; SPDM) in combination with nano-probing using COMBO-FISH (COMBinatorial Oligonucleotide FISH), novel insights into the nano-architecture of the genome will become possible. The native spatial structure of trinucleotide repeat expansion genome regions was analysed and optical sequencing of repetitive units was performed within 3D-conserved nuclei using SPDM after COMBO-FISH. We analysed a (CGG)n-expansion region inside the 5' untranslated region of the FMR1 gene. The number of CGG repeats for a full mutation causing the Fragile-X syndrome was found and also verified by Southern blot. The FMR1 promotor region was similarly condensed like a centromeric region whereas the arrangement of the probes labelling the expansion region seemed to indicate a loop-like nano-structure. These results for the first time demonstrate that in situ chromatin structure measurements on the nanoscale are feasible. Due to further methodological progress it will become possible to estimate the state of trinucleotide repeat mutations in detail and to determine the associated chromatin strand structural changes on the single cell level. In general, the application of the described approach to any genome region will lead to new insights into genome nano-architecture and open new avenues for understanding mechanisms and their relevance in the development of heredity diseases.
Directory of Open Access Journals (Sweden)
Abílio Amiguinho
2005-01-01
Full Text Available The process of socio-educational territorialisation in rural contexts is the topic of this text. The theme corresponds to a challenge to address it having as main axis of discussion either the problem of social exclusion or that of local development. The reasons to locate the discussion in this last field of analysis are discussed in the first part of the text. Theoretical and political reasons are there articulated because the question is about projects whose intentions and practices call for the political both in the theoretical debate and in the choices that anticipate intervention. From research conducted for several years, I use contributions that aim at discuss and enlighten how school can be a potential locus of local development. Its identification and recognition as local institution (either because of those that work and live in it or because of those that act in the surrounding context are crucial steps to progressively constitute school as a partner for development. The promotion of the local values and roots, the reconstruction of socio-personal and local identities, the production of sociabilities and the equation and solution of shared problems were the dimensions of a socio-educative intervention, markedly globalising. This scenario, as it is argued, was also, intentionally, one of transformation and of deliberate change of school and of the administration of the educative territoires.
Multifield DBI Inflation and Non-Gaussianities
Huang, Min-xin; Underwood, Bret
2008-01-01
We analyze the trajectories for multifield DBI inflation, which can arise in brane inflation models, and show that the trajectories are the same as in typical slow roll inflation. We calculate the power spectrum and find that the higher derivative terms of the DBI action lead to a suppression of the contribution from the isocurvature perturbations. We also calculate the bispectrum generated by the isocurvature perturbation, and find that it leads to distinctive features.
Non-Gaussian Statistical Communication Theory
Middleton, David
2012-01-01
The book is based on the observation that communication is the central operation of discovery in all the sciences. In its "active mode" we use it to "interrogate" the physical world, sending appropriate "signals" and receiving nature's "reply". In the "passive mode" we receive nature's signals directly. Since we never know a prioriwhat particular return signal will be forthcoming, we must necessarily adopt a probabilistic model of communication. This has developed over the approximately seventy years since it's beginning, into a Statistical Communication Theory (or SCT). Here it is the set or
Adaptive Filtering for Non-Gaussian Processes
DEFF Research Database (Denmark)
Kidmose, Preben
2000-01-01
A new stochastic gradient robust filtering method, based on a non-linear amplitude transformation, is proposed. The method requires no a priori knowledge of the characteristics of the input signals and it is insensitive to the signals distribution and to the stationarity of the signals. A simulat...
Bregman Cost for Non-Gaussian Noise
DEFF Research Database (Denmark)
Burger, Martin; Dong, Yiqiu; Sciacchitano, Federica
estimator for the Bregman cost if the image is corrupted by Gaussian noise. In this work we extend this result to other noise models with log-concave likelihood density, by introducing two related Bregman cost functions for which the CM and the MAP estimates are proper Bayes estima-tors. Moreover, we also....... From a theoretical point of view it has been argued that the MAP estimate is only in an asymptotic sense a Bayes estimator for the uniform cost function, while the CM estimate is a Bayes estimator for the means squared cost function. Recently, it has been proven that the MAP estimate is a proper Bayes...
CMBPol Mission Concept Study: Probing Inflation with CMB Polarization
Baumann, Daniel; Adshead, Peter; Amblard, Alexandre; Ashoorioon, Amjad; Bartolo, Nicola; Bean, Rachel; Beltran, Maria; de Bernardis, Francesco; Bird, Simeon; Chen, Xingang; Chung, Daniel Jun Hun; Colombo, Loris; Cooray, Asantha R.; Creminelli, Paolo; Dodelson, Scott; Dunkley, Joanna; Dvorkin, Cora; Easther, Richard; Finelli, Fabio; Flauger, Raphael; Hertzberg, Mark P.; Jones-Smith, Katherine; Kachru, Shamit; Kadota, Kenji; Khoury, Justin; Kinney, William H.; Komatsu, Eiichiro; Krauss, Lawrence M.; Lesgourgues, Julien; Liddle, Andrew R.; Liguori, Michele; Lim, Eugene A.; Linde, Andrei D.; Matarrese, Sabino; Mathur, Harsh; McAllister, Liam; Melchiorri, Alessandro; Nicolis, Alberto; Pagano, Luca; Peiris, Hiranya V.; Peloso, Marco; Pogosian, Levon; Pierpaoli, Elena; Riotto, Antonio; Seljak, Uros; Senatore, Leonardo; Shandera, Sarah E.; Silverstein, Eva; Smith, Tristan; Vaudrevange, Pascal M.; Verde, Licia; Wandelt, Ben; Wands, David; Watson, Scott; Wyman, Mark; Yadav, Amit; Valkenburg, Wessel; Zaldarriaga, Matias
2009-01-01
We summarize the utility of precise cosmic microwave background (CMB) polarization measurements as probes of the physics of inflation. We focus on the prospects for using CMB measurements to differentiate various inflationary mechanisms. In particular, a detection of primordial B-mode polarization would demonstrate that inflation occurred at a very high energy scale, and that the inflaton traversed a super-Planckian distance in field space. We explain how such a detection or constraint would illuminate aspects of physics at the Planck scale. Moreover, CMB measurements can constrain the scale-dependence and non-Gaussianity of the primordial fluctuations and limit the possibility of a significant isocurvature contribution. Each such limit provides crucial information on the underlying inflationary dynamics. Finally, we quantify these considerations by presenting forecasts for the sensitivities of a future satellite experiment to the inflationary parameters.
Directory of Open Access Journals (Sweden)
Knopp Michael V
2007-12-01
Full Text Available Abstract Background 18F-fluorodeoxyglucose (18F-FDG positron emission tomography/computed tomography (PET/CT has become an established method for detecting hypermetabolic sites of known and occult disease and is widely used in oncology surgical planning. Intraoperatively, it is often difficult to localize tumors and verify complete resection of tumors that have been previously detected on diagnostic PET/CT at the time of the original evaluation of the cancer patient. Therefore, we propose an innovative approach for intraoperative tumor localization and verification of complete tumor resection utilizing 18F-FDG for perioperative PET/CT imaging and intraoperative gamma probe detection. Methods Two breast cancer patients were evaluated. 18F-FDG was administered and PET/CT was acquired immediately prior to surgery. Intraoperatively, tumors were localized and resected with the assistance of a handheld gamma probe. Resected tumors were scanned with specimen PET/CT prior to pathologic processing. Shortly after the surgical procedure, patients were re-imaged with PET/CT utilizing the same preoperatively administered 18F-FDG dose. Results One patient had primary carcinoma of breast and a metastatic axillary lymph node. The second patient had a solitary metastatic liver lesion. In both cases, preoperative PET/CT verified these findings and demonstrated no additional suspicious hypermetabolic lesions. Furthermore, intraoperative gamma probe detection, specimen PET/CT, and postoperative PET/CT verified complete resection of the hypermetabolic lesions. Conclusion Immediate preoperative and postoperative PET/CT imaging, utilizing the same 18F-FDG injection dose, is feasible and image quality is acceptable. Such perioperative PET/CT imaging, along with intraoperative gamma probe detection and specimen PET/CT, can be used to verify complete tumor resection. This innovative approach demonstrates promise for assisting the oncologic surgeon in localizing and
Squeezed bispectrum in the δ N formalism: local observer effect in field space
Energy Technology Data Exchange (ETDEWEB)
Tada, Yuichiro [Kavli Institute for the Physics and Mathematics of the Universe (WPI), UTIAS, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan); Vennin, Vincent, E-mail: yuichiro.tada@ipmu.jp, E-mail: vincent.vennin@port.ac.uk [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Burnaby Road, Portsmouth, PO1 3FX (United Kingdom)
2017-02-01
The prospects of future galaxy surveys for non-Gaussianity measurements call for the development of robust techniques for computing the bispectrum of primordial cosmological perturbations. In this paper, we propose a novel approach to the calculation of the squeezed bispectrum in multiple-field inflation. With use of the δ N formalism, our framework sheds new light on the recently pointed out difference between the squeezed bispectrum for global observers and that for local observers, while allowing one to calculate both. For local observers in particular, the squeezed bispectrum is found to vanish in single-field inflation. Furthermore, our framework allows one to go beyond the near-equilateral ('small hierarchy') limit, and to automatically include intrinsic non-Gaussianities that do not need to be calculated separately. The explicit computational programme of our method is given and illustrated with a few examples.
Gemelli, Marcellino; Abelmann, Leon; Engelen, Johannes Bernardus Charles; Khatib, M.G.; Koelmans, W.W.; Zaboronski, Olog; Campardo, Giovanni; Tiziani, Federico; Laculo, Massimo
2011-01-01
This chapter gives an overview of probe-based data storage research over the last three decades, encompassing all aspects of a probe recording system. Following the division found in all mechanically addressed storage systems, the different subsystems (media, read/write heads, positioning, data
DEFF Research Database (Denmark)
Madsen, Jacob Østergaard
The aim of this study was thus to explore cultural probes (Gaver, Boucher et al. 2004), as a possible methodical approach, supporting knowledge production on situated and contextual aspects of occupation.......The aim of this study was thus to explore cultural probes (Gaver, Boucher et al. 2004), as a possible methodical approach, supporting knowledge production on situated and contextual aspects of occupation....
International Nuclear Information System (INIS)
Denis, J.; Decaudin, J.M.
1984-01-01
The probe includes optical means of refractive index n, refracting an incident light beam from a medium with a refractive index n1>n and reflecting an incident light beam from a medium with a refractive index n2 [fr
The clustering of local maxima in random noise
International Nuclear Information System (INIS)
Coles, P.
1989-01-01
A mixture of analytic and numerical techniques is used to study the clustering properties of local maxima of random noise. Technical complexities restrict us to the case of 1D noise, but the results obtained should give a reasonably accurate picture of the behaviour of cosmological density peaks in noise defined on a 3D domain. We give estimates of the two-point correlation function of local maxima, for both Gaussian and non-Gaussian noise and show that previous approximations are not accurate. (author)
International Nuclear Information System (INIS)
Matsumoto, Haruya; Kaya, Nobuyuki; Yuasa, Kazuhiro; Hayashi, Tomoaki
1976-01-01
Electron counting method has been devised and experimented for the purpose of measuring electron temperature and density, the most fundamental quantities to represent plasma conditions. Electron counting is a method to count the electrons in plasma directly by equipping a probe with the secondary electron multiplier. It has three advantages of adjustable sensitivity, high sensitivity of the secondary electron multiplier, and directional property. Sensitivity adjustment is performed by changing the size of collecting hole (pin hole) on the incident front of the multiplier. The probe is usable as a direct reading thermometer of electron temperature because it requires to collect very small amount of electrons, thus it doesn't disturb the surrounding plasma, and the narrow sweep width of the probe voltage is enough. Therefore it can measure anisotropy more sensitively than a Langmuir probe, and it can be used for very low density plasma. Though many problems remain on anisotropy, computer simulation has been carried out. Also it is planned to provide a Helmholtz coil in the vacuum chamber to eliminate the effect of earth magnetic field. In practical experiments, the measurement with a Langmuir probe and an emission probe mounted to the movable structure, the comparison with the results obtained in reverse magnetic field by using a Helmholtz coil, and the measurement of ionic sound wave are scheduled. (Wakatsuki, Y.)
High spatial resolution Kelvin probe force microscopy with coaxial probes
International Nuclear Information System (INIS)
Brown, Keith A; Westervelt, Robert M; Satzinger, Kevin J
2012-01-01
Kelvin probe force microscopy (KPFM) is a widely used technique to measure the local contact potential difference (CPD) between an AFM probe and the sample surface via the electrostatic force. The spatial resolution of KPFM is intrinsically limited by the long range of the electrostatic interaction, which includes contributions from the macroscopic cantilever and the conical tip. Here, we present coaxial AFM probes in which the cantilever and cone are shielded by a conducting shell, confining the tip–sample electrostatic interaction to a small region near the end of the tip. We have developed a technique to measure the true CPD despite the presence of the shell electrode. We find that the behavior of these probes agrees with an electrostatic model of the force, and we observe a factor of five improvement in spatial resolution relative to unshielded probes. Our discussion centers on KPFM, but the field confinement offered by these probes may improve any variant of electrostatic force microscopy. (paper)
International Nuclear Information System (INIS)
Castelino, J.
1992-01-01
The creation of DNA probes for detection of specific nucleotide segments differs from ligand detection in that it is a chemical rather than an immunological reaction. Complementary DNA or RNA is used in place of the antibody and is labelled with 32 P. So far, DNA probes have been successfully employed in the diagnosis of inherited disorders, infectious diseases, and for identification of human oncogenes. The latest approach to the diagnosis of communicable and parasitic infections is based on the use of deoxyribonucleic acid (DNA) probes. The genetic information of all cells is encoded by DNA and DNA probe approach to identification of pathogens is unique because the focus of the method is the nucleic acid content of the organism rather than the products that the nucleic acid encodes. Since every properly classified species has some unique nucleotide sequences that distinguish it from every other species, each organism's genetic composition is in essence a finger print that can be used for its identification. In addition to this specificity, DNA probes offer other advantages in that pathogens may be identified directly in clinical specimens
Energy Technology Data Exchange (ETDEWEB)
Castelino, J
1993-12-31
The creation of DNA probes for detection of specific nucleotide segments differs from ligand detection in that it is a chemical rather than an immunological reaction. Complementary DNA or RNA is used in place of the antibody and is labelled with {sup 32}P. So far, DNA probes have been successfully employed in the diagnosis of inherited disorders, infectious diseases, and for identification of human oncogenes. The latest approach to the diagnosis of communicable and parasitic infections is based on the use of deoxyribonucleic acid (DNA) probes. The genetic information of all cells is encoded by DNA and DNA probe approach to identification of pathogens is unique because the focus of the method is the nucleic acid content of the organism rather than the products that the nucleic acid encodes. Since every properly classified species has some unique nucleotide sequences that distinguish it from every other species, each organism`s genetic composition is in essence a finger print that can be used for its identification. In addition to this specificity, DNA probes offer other advantages in that pathogens may be identified directly in clinical specimens 10 figs, 2 tabs
2008-01-01
The Thermal and Electrical Conductivity Probe (TECP) for NASA's Phoenix Mars Lander took measurements in Martian soil and in the air. The needles on the end of the instrument were inserted into the Martian soil, allowing TECP to measure the propagation of both thermal and electrical energy. TECP also measured the humidity in the surrounding air. The needles on the probe are 15 millimeters (0.6 inch) long. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.
International Nuclear Information System (INIS)
Laget, J.M.
1986-11-01
Specificity and complementarity of hadron and electron probes must be systematically developed to answer three questions currently asked in intermediate energy nuclear physics: what is nucleus structure at short distances, what is nature of short range correlations, what is three body force nature [fr
International Nuclear Information System (INIS)
Xu, Shuai; Song, Xue-ke; Shi, Jia-dong; Ye, Liu
2014-01-01
In this Letter, we analytically explore the effect of the Hawking radiation on the quantum correlation and Bell non-locality for Dirac particles in the background of Schwarzschild black hole. It is shown that when the Hawking effect is almost nonexistent, corresponding to the case of an almost extreme black hole, the quantum properties of physically accessible state are the same for the initial situation. For finite Hawking temperature T, the accessible quantum correlation monotonously decreases along with increasing T owing to the thermal fields generated by the Hawking effect, and the accessible quantum non-locality will be disappeared when the Hawking temperature is more than a fixed value which increases with the parameter r of Werner state growing. Then we analyze the redistribution of quantum correlation, and find that for the case of the Hawking temperature being infinite, corresponding to the case of the black hole evaporating completely, the quantum correlation of physically accessible state is equal to the one of the inaccessible states. Moreover, due to the Pauli exclusion principle and the differences between Fermi–Dirac and Bose–Einstein statistics, for the Dirac fields the accessible classical correlation decreases with increase of the Hawking temperature, which is different for the scalar fields. For Bell non-locality, we also find that the quantum non-locality is always extinct for physically inaccessible states, and the strength of the non-locality decreases with enlarging intensity of Hawking effect when the non-locality is existent in physically accessible state.
Energy Technology Data Exchange (ETDEWEB)
Krupnik, L.I.; Chmyga, A.A.; Komarov, A.D.; Kozachok, A.S.; Zhezhera, A.I. [Institute of Plasma Physics, NSC KIPT, 310108 Kharkov (Ukraine); Melnikov, A.V.; Eliseev, L.G.; Lysenko, S.E.; Mavrin, V.A.; Perfilov, S.V. [Institute of Nuclear Fusion, RRC ' Kurchatov Institute' , Moscow (Russian Federation); Hidalgo, C.; Ascasibar, E.; Estrada, T.; Liniers, M.; Ochando, M.A.; Pablos, J.L. de; Pedrosa, M.A.; Tabares, F. [Laboratorio Nacional de Fusion por Confinamiento Magnetico, Asociacion EURATOM-CIEMAT, 28040-Madrid (Spain)
2011-07-01
One of essential achievements of the Heavy Ion Beam Probe (HIBP) diagnostics is the possibility to use it for investigation of plasma confinement by measuring the fluctuations of electric field and plasma density; the method is based on the important role of the plasma electric fields. Both edge and core transport barriers are related to a large increase in the E*B sheared flows in a fusion device. In the TJ-II stellarator the HIBP diagnostics has recently been upgraded for two-point measurements with a good spatial (1 cm) and temporal (10 {mu}s) resolution of the plasma electric potential and density, as well as their fluctuations and poloidal component of electric field, E{sub p} equals ({phi}1 - {phi}2)/{Delta}r [V/cm]; these data give chance to extract the radial turbulent particle flux: {Gamma}(r) equals {Gamma}(Epol*Btor) equals {Gamma}(E*B). (authors)
Czech Academy of Sciences Publication Activity Database
Balliou, A.; Kazim, Samrana; Pfleger, Jiří; Rakušan, J.; Skoulatakis, G.; Kennou, S.; Glezos, N.
2016-01-01
Roč. 253, č. 5 (2016), s. 1009-1019 ISSN 0370-1972 R&D Projects: GA MŠk(CZ) 7AMB12GR022; GA ČR(CZ) GAP108/12/1143 Institutional support: RVO:61389013 Keywords : Au nanoparticles * carrier localization * electrical transport Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.674, year: 2016
International Nuclear Information System (INIS)
Anon.
1976-01-01
A number of 13 N-labeled compounds have been enzymatically synthesized and are being evaluated as tumor and/or organ localizing agents. 13 N-Ammonia, produced after cyclotron generation of 13 N-nitrate and subsequent reduction was used to enzymatically aminate the appropriate substrate to yield 13 N-L-glutamic acid, L-glutamine, L-asparagine, L-valine, L-leucine and L-alanine. The use of 13 N-asparagine as a myocardial scanning agent and as a tumor localizing agent in asparaginase-sensitive tumors is discussed. Two imaging devices were used to study the effectiveness of the compounds as localizing agents. For static whole body distribution studies, a dual-detector high energy gamma ray (HEG) rectilinear scanner, equipped with constant response collimators was employed. The uniformity of response of this system permits quantitative determination of the amount of 13 N activity present in the organ or tumor of interest. The total organ kinetic imaging monitor (TOKIM) gamma camera system was used for dynamic studies covering smaller areas of the subject's body
The time domain triple probe method
International Nuclear Information System (INIS)
Meier, M.A.; Hallock, G.A.; Tsui, H.Y.W.; Bengtson, R.D.
1994-01-01
A new Langmuir probe technique based on the triple probe method is being developed to provide simultaneous measurement of plasma temperature, potential, and density with the temporal and spatial resolution required to accurately characterize plasma turbulence. When the conventional triple probe method is used in an inhomogeneous plasma, local differences in the plasma measured at each probe introduce significant error in the estimation of turbulence parameters. The Time Domain Triple Probe method (TDTP) uses high speed switching of Langmuir probe potential, rather than spatially separated probes, to gather the triple probe information thus avoiding these errors. Analysis indicates that plasma response times and recent electronics technology meet the requirements to implement the TDTP method. Data reduction techniques of TDTP data are to include linear and higher order correlation analysis to estimate fluctuation induced particle and thermal transport, as well as energy relationships between temperature, density, and potential fluctuations
Energy Technology Data Exchange (ETDEWEB)
Żurek-Biesiada, Dominika [Laboratory of Cell Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków (Poland); Szczurek, Aleksander T. [Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz (Germany); Prakash, Kirti [Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz (Germany); Institute for Pharmacy and Molecular Biotechnology (IPMB), University of Heidelberg, Im Neuenheimer Feld 364, D-69120 Heidelberg (Germany); Mohana, Giriram K. [Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz (Germany); Lee, Hyun-Keun [Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz (Germany); Department of Physics, University of Mainz (JGU), Staudingerweg 7, 55128 Mainz (Germany); Roignant, Jean-Yves [Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz (Germany); Birk, Udo J. [Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz (Germany); Department of Physics, University of Mainz (JGU), Staudingerweg 7, 55128 Mainz (Germany); Dobrucki, Jurek W., E-mail: jerzy.dobrucki@uj.edu.pl [Laboratory of Cell Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków (Poland); Cremer, Christoph, E-mail: c.cremer@imb-mainz.de [Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz (Germany); Institute for Pharmacy and Molecular Biotechnology (IPMB), University of Heidelberg, Im Neuenheimer Feld 364, D-69120 Heidelberg (Germany); Department of Physics, University of Mainz (JGU), Staudingerweg 7, 55128 Mainz (Germany)
2016-05-01
Higher order chromatin structure is not only required to compact and spatially arrange long chromatids within a nucleus, but have also important functional roles, including control of gene expression and DNA processing. However, studies of chromatin nanostructures cannot be performed using conventional widefield and confocal microscopy because of the limited optical resolution. Various methods of superresolution microscopy have been described to overcome this difficulty, like structured illumination and single molecule localization microscopy. We report here that the standard DNA dye Vybrant{sup ®} DyeCycle™ Violet can be used to provide single molecule localization microscopy (SMLM) images of DNA in nuclei of fixed mammalian cells. This SMLM method enabled optical isolation and localization of large numbers of DNA-bound molecules, usually in excess of 10{sup 6} signals in one cell nucleus. The technique yielded high-quality images of nuclear DNA density, revealing subdiffraction chromatin structures of the size in the order of 100 nm; the interchromatin compartment was visualized at unprecedented optical resolution. The approach offers several advantages over previously described high resolution DNA imaging methods, including high specificity, an ability to record images using a single wavelength excitation, and a higher density of single molecule signals than reported in previous SMLM studies. The method is compatible with DNA/multicolor SMLM imaging which employs simple staining methods suited also for conventional optical microscopy. - Highlights: • Super-resolution imaging of nuclear DNA with Vybrant Violet and blue excitation. • 90nm resolution images of DNA structures in optically thick eukaryotic nuclei. • Enhanced resolution confirms the existence of DNA-free regions inside the nucleus. • Optimized imaging conditions enable multicolor super-resolution imaging.
Local vs Nonlocal States in FeTiO3 Probed with 1s2pRIXS: Implications for Photochemistry.
Hunault, Myrtille O J Y; Khan, Wilayat; Minár, Jan; Kroll, Thomas; Sokaras, Dimosthenis; Zimmermann, Patric; Delgado-Jaime, Mario U; de Groot, Frank M F
2017-09-18
Metal-metal charge transfer (MMCT) is expected to be the main mechanism that enables the harvesting of solar light by iron-titanium oxides for photocatalysis. We have studied FeTiO 3 as a model compound for MMCT with 1s2pRIXS at the Fe K-edge. The high-energy resolution XANES enables distinguishing five pre-edge features. The three first well distinct RIXS features are assigned to electric quadrupole transitions to the localized Fe* 3d states, shifted to lower energy by the 1s core-hole. Crystal field multiplet calculations confirm the speciation of divalent iron. The contribution of electric dipole absorption due to local p-d mixing allowed by the trigonal distortion of the cation site is supported by DFT and CFM calculations. The two other nonlocal features are assigned to electric dipole transitions to excited Fe* 4p states mixed with the neighboring Ti 3d states. The comparison with DFT calculations demonstrates that MMCT in ilmenite is favored by the hybridization between the Fe 4p and delocalized Ti 3d orbitals via the O 2p orbitals.
Atom-probe tomography the local electrode atom probe
Miller, Michael K
2014-01-01
In this comprehensive introduction to the use of APT in nanocharacterization, readers will find everything they need to get up to speed on the technique, from the core physics to state-of-the-art instrumentation and revised methods of data analysis.
NASA's interstellar probe mission
International Nuclear Information System (INIS)
Liewer, P.C.; Ayon, J.A.; Wallace, R.A.; Mewaldt, R.A.
2000-01-01
NASA's Interstellar Probe will be the first spacecraft designed to explore the nearby interstellar medium and its interaction with our solar system. As envisioned by NASA's Interstellar Probe Science and Technology Definition Team, the spacecraft will be propelled by a solar sail to reach >200 AU in 15 years. Interstellar Probe will investigate how the Sun interacts with its environment and will directly measure the properties and composition of the dust, neutrals and plasma of the local interstellar material which surrounds the solar system. In the mission concept developed in the spring of 1999, a 400-m diameter solar sail accelerates the spacecraft to ∼15 AU/year, roughly 5 times the speed of Voyager 1 and 2. The sail is used to first bring the spacecraft to ∼0.25 AU to increase the radiation pressure before heading out in the interstellar upwind direction. After jettisoning the sail at ∼5 AU, the spacecraft coasts to 200-400 AU, exploring the Kuiper Belt, the boundaries of the heliosphere, and the nearby interstellar medium
Federal Laboratory Consortium — The Proximal Probes Facility consists of laboratories for microscopy, spectroscopy, and probing of nanostructured materials and their functional properties. At the...
Probe Techniques. Introductory Remarks
Energy Technology Data Exchange (ETDEWEB)
Emeleus, K. G. [School of Physics and Applied Mathematics, Queen' s University, Belfast (United Kingdom)
1968-04-15
In this brief introduction to the session on probes, the history of theii development is first touched on briefly. Reference is then made to the significance of the work to be described by Medicus, for conductivity and recombination calculations, and by Lam and Su, for a wide range of medium and higher pressure plasmas. Finally, a number of other probe topics are mentioned, including multiple probes; probes in electronegative plasmas; resonance probes; probes in noisy discharges; probes as oscillation detectors; use of probes where space-charge is not negligible. (author)
Probing plasmonic nanostructures by photons and electrons
DEFF Research Database (Denmark)
Kneipp, Katrin; Kneipp, Harald; Kneipp, Janina
2015-01-01
We discuss recent developments for studying plasmonic metal nanostructures. Exploiting photons and electrons opens up new capabilities to probe the complete plasmon spectrum including bright and dark modes and related local optical fields at subnanometer spatial resolution. This comprehensive cha...
DEFF Research Database (Denmark)
Wang, Fei; Petersen, Dirch Hjorth; Østerberg, Frederik Westergaard
2009-01-01
In this paper, we discuss a probe spacing dependence study in order to estimate the accuracy of micro four-point probe measurements on inhomogeneous samples. Based on sensitivity calculations, both sheet resistance and Hall effect measurements are studied for samples (e.g. laser annealed samples...... the probe spacing is smaller than 1/40 of the variation wavelength, micro four-point probes can provide an accurate record of local properties with less than 1% measurement error. All the calculations agree well with previous experimental results.......) with periodic variations of sheet resistance, sheet carrier density, and carrier mobility. With a variation wavelength of Â¿, probe spacings from 0.0012 to 1002 have been applied to characterize the local variations. The calculations show that the measurement error is highly dependent on the probe spacing. When...
Nichols, M. E.
1976-01-01
Results are presented of wind tunnel test 0A161 of a 0.030-scale model 45-0 of the configuration 140A/B (modified) space shuttle vehicle orbiter in the NASA Ames Research Center Unitary Plan Wind Tunnel facilities. The purpose of this test was to determine local total and static pressure environments for the air data probe locations and relative effectiveness of alternate flight-test probe configurations. Testing was done in the Mach number range from 0.30 to 3.5. Angle of attack was varied from -8 to 25 degrees while sideslip varied between -8 and 8 degrees.
Building versatile bipartite probes for quantum metrology
Farace, Alessandro; De Pasquale, Antonella; Adesso, Gerardo; Giovannetti, Vittorio
2016-01-01
We consider bipartite systems as versatile probes for the estimation of transformations acting locally on one of the subsystems. We investigate what resources are required for the probes to offer a guaranteed level of metrological performance, when the latter is averaged over specific sets of local transformations. We quantify such a performance via the average skew information (AvSk), a convex quantity which we compute in closed form for bipartite states of arbitrary dimensions, and which is shown to be strongly dependent on the degree of local purity of the probes. Our analysis contrasts and complements the recent series of studies focused on the minimum, rather than the average, performance of bipartite probes in local estimation tasks, which was instead determined by quantum correlations other than entanglement. We provide explicit prescriptions to characterize the most reliable states maximizing the AvSk, and elucidate the role of state purity, separability and correlations in the classification of optimal probes. Our results can help in the identification of useful resources for sensing, estimation and discrimination applications when complete knowledge of the interaction mechanism realizing the local transformation is unavailable, and access to pure entangled probes is technologically limited.
Building versatile bipartite probes for quantum metrology
International Nuclear Information System (INIS)
Farace, Alessandro; Pasquale, Antonella De; Giovannetti, Vittorio; Adesso, Gerardo
2016-01-01
We consider bipartite systems as versatile probes for the estimation of transformations acting locally on one of the subsystems. We investigate what resources are required for the probes to offer a guaranteed level of metrological performance, when the latter is averaged over specific sets of local transformations. We quantify such a performance via the average skew information (AvSk), a convex quantity which we compute in closed form for bipartite states of arbitrary dimensions, and which is shown to be strongly dependent on the degree of local purity of the probes. Our analysis contrasts and complements the recent series of studies focused on the minimum, rather than the average, performance of bipartite probes in local estimation tasks, which was instead determined by quantum correlations other than entanglement. We provide explicit prescriptions to characterize the most reliable states maximizing the AvSk, and elucidate the role of state purity, separability and correlations in the classification of optimal probes. Our results can help in the identification of useful resources for sensing, estimation and discrimination applications when complete knowledge of the interaction mechanism realizing the local transformation is unavailable, and access to pure entangled probes is technologically limited. (paper)
Frank, Jeffrey I.; Rosengart, Axel J.; Kasza, Ken; Yu, Wenhua; Chien, Tai-Hsin; Franklin, Jeff
2006-10-10
Apparatuses, systems, methods, and computer code for, among other things, monitoring the health of samples such as the brain while providing local cooling or heating. A representative device is a heat transfer probe, which includes an inner channel, a tip, a concentric outer channel, a first temperature sensor, and a second temperature sensor. The inner channel is configured to transport working fluid from an inner inlet to an inner outlet. The tip is configured to receive at least a portion of the working fluid from the inner outlet. The concentric outer channel is configured to transport the working fluid from the inner outlet to an outer outlet. The first temperature sensor is coupled to the tip, and the second temperature sensor spaced apart from the first temperature sensor.
International Nuclear Information System (INIS)
Yu, Jie; Chen, Kuilin; Mori, Junichi; Rashid, Mudassir M.
2013-01-01
Optimizing wind power generation and controlling the operation of wind turbines to efficiently harness the renewable wind energy is a challenging task due to the intermittency and unpredictable nature of wind speed, which has significant influence on wind power production. A new approach for long-term wind speed forecasting is developed in this study by integrating GMCM (Gaussian mixture copula model) and localized GPR (Gaussian process regression). The time series of wind speed is first classified into multiple non-Gaussian components through the Gaussian mixture copula model and then Bayesian inference strategy is employed to incorporate the various non-Gaussian components using the posterior probabilities. Further, the localized Gaussian process regression models corresponding to different non-Gaussian components are built to characterize the stochastic uncertainty and non-stationary seasonality of the wind speed data. The various localized GPR models are integrated through the posterior probabilities as the weightings so that a global predictive model is developed for the prediction of wind speed. The proposed GMCM–GPR approach is demonstrated using wind speed data from various wind farm locations and compared against the GMCM-based ARIMA (auto-regressive integrated moving average) and SVR (support vector regression) methods. In contrast to GMCM–ARIMA and GMCM–SVR methods, the proposed GMCM–GPR model is able to well characterize the multi-seasonality and uncertainty of wind speed series for accurate long-term prediction. - Highlights: • A novel predictive modeling method is proposed for long-term wind speed forecasting. • Gaussian mixture copula model is estimated to characterize the multi-seasonality. • Localized Gaussian process regression models can deal with the random uncertainty. • Multiple GPR models are integrated through Bayesian inference strategy. • The proposed approach shows higher prediction accuracy and reliability
A Non-Gaussian Spatial Generalized Linear Latent Variable Model
Irincheeva, Irina
2012-08-03
We consider a spatial generalized linear latent variable model with and without normality distributional assumption on the latent variables. When the latent variables are assumed to be multivariate normal, we apply a Laplace approximation. To relax the assumption of marginal normality in favor of a mixture of normals, we construct a multivariate density with Gaussian spatial dependence and given multivariate margins. We use the pairwise likelihood to estimate the corresponding spatial generalized linear latent variable model. The properties of the resulting estimators are explored by simulations. In the analysis of an air pollution data set the proposed methodology uncovers weather conditions to be a more important source of variability than air pollution in explaining all the causes of non-accidental mortality excluding accidents. © 2012 International Biometric Society.
A Non-Gaussian Spatial Generalized Linear Latent Variable Model
Irincheeva, Irina; Cantoni, Eva; Genton, Marc G.
2012-01-01
We consider a spatial generalized linear latent variable model with and without normality distributional assumption on the latent variables. When the latent variables are assumed to be multivariate normal, we apply a Laplace approximation. To relax the assumption of marginal normality in favor of a mixture of normals, we construct a multivariate density with Gaussian spatial dependence and given multivariate margins. We use the pairwise likelihood to estimate the corresponding spatial generalized linear latent variable model. The properties of the resulting estimators are explored by simulations. In the analysis of an air pollution data set the proposed methodology uncovers weather conditions to be a more important source of variability than air pollution in explaining all the causes of non-accidental mortality excluding accidents. © 2012 International Biometric Society.
Confronting Passive and Active Sensors with Non-Gaussian Statistics
Directory of Open Access Journals (Sweden)
Pablo Rodríguez-Gonzálvez
2014-07-01
Full Text Available This paper has two motivations: firstly, to compare the Digital Surface Models (DSM derived by passive (digital camera and by active (terrestrial laser scanner remote sensing systems when applied to specific architectural objects, and secondly, to test how well the Gaussian classic statistics, with its Least Squares principle, adapts to data sets where asymmetrical gross errors may appear and whether this approach should be changed for a non-parametric one. The field of geomatic technology automation is immersed in a high demanding competition in which any innovation by one of the contenders immediately challenges the opponents to propose a better improvement. Nowadays, we seem to be witnessing an improvement of terrestrial photogrammetry and its integration with computer vision to overcome the performance limitations of laser scanning methods. Through this contribution some of the issues of this “technological race” are examined from the point of view of photogrammetry. A new software is introduced and an experimental test is designed, performed and assessed to try to cast some light on this thrilling match. For the case considered in this study, the results show good agreement between both sensors, despite considerable asymmetry. This asymmetry suggests that the standard Normal parameters are not adequate to assess this type of data, especially when accuracy is of importance. In this case, standard deviation fails to provide a good estimation of the results, whereas the results obtained for the Median Absolute Deviation and for the Biweight Midvariance are more appropriate measures.
Football fever: goal distributions and non-Gaussian statistics
Bittner, E.; Nußbaumer, A.; Janke, W.; Weigel, M.
2009-02-01
Analyzing football score data with statistical techniques, we investigate how the not purely random, but highly co-operative nature of the game is reflected in averaged properties such as the probability distributions of scored goals for the home and away teams. As it turns out, especially the tails of the distributions are not well described by the Poissonian or binomial model resulting from the assumption of uncorrelated random events. Instead, a good effective description of the data is provided by less basic distributions such as the negative binomial one or the probability densities of extreme value statistics. To understand this behavior from a microscopical point of view, however, no waiting time problem or extremal process need be invoked. Instead, modifying the Bernoulli random process underlying the Poissonian model to include a simple component of self-affirmation seems to describe the data surprisingly well and allows to understand the observed deviation from Gaussian statistics. The phenomenological distributions used before can be understood as special cases within this framework. We analyzed historical football score data from many leagues in Europe as well as from international tournaments, including data from all past tournaments of the “FIFA World Cup” series, and found the proposed models to be applicable rather universally. In particular, here we analyze the results of the German women’s premier football league and consider the two separate German men’s premier leagues in the East and West during the cold war times as well as the unified league after 1990 to see how scoring in football and the component of self-affirmation depend on cultural and political circumstances.
Spectral Estimation of Non-Gaussian Time Series
Czech Academy of Sciences Publication Activity Database
Fabián, Zdeněk
2010-01-01
Roč. 20, č. 4 (2010), s. 491-499 ISSN 1210-0552 R&D Projects: GA MŠk ME 949 Institutional research plan: CEZ:AV0Z10300504 Keywords : scalar score * power spectra * processes with infinite variance * processes with skewed distribution s Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 0.511, year: 2010
Non-Gaussianity and the Cosmic Microwave Background Anisotropies
Directory of Open Access Journals (Sweden)
N. Bartolo
2010-01-01
microwave background (CMB anisotropies. We first show how to set the initial conditions at second order for the CMB anisotropies when some primordial NG is present. However, there are many sources of NG in CMB anisotropies, beyond the primordial one, which can contaminate the primordial signal. We mainly focus on the NG generated from the post inflationary evolution of the CMB anisotropies at second order in perturbation theory at large and small angular scales, such as the ones generated at the recombination epoch. We show how to derive the equations to study the second-order CMB anisotropies and provide analytical computations to evaluate their contamination to primordial NG (complemented with numerical examples. We also offer a brief summary of other secondary effects. This paper requires basic knowledge of the theory of cosmological perturbations at the linear level.
Inflationary magnetogenesis with added helicity: constraints from non-Gaussianities
Caprini, Chiara; Chiara Guzzetti, Maria; Sorbo, Lorenzo
2018-06-01
In previous work (Caprini and Sorbo 2014 J. Cosmol. Astropart. Phys. JCAP10(2014)056), two of us have proposed a model of inflationary magnetogenesis based on a rolling auxiliary field able both to account for the magnetic fields inferred by the (non) observation of gamma-rays from blazars, and to start the galactic dynamo, without incurring in any strong coupling or strong backreaction regime. Here we evaluate the correction to the scalar spectrum and bispectrum with respect to single-field slow-roll inflation generated in that scenario. The strongest constraints on the model originate from the non-observation of a scalar bispectrum. Nevertheless, even when those constraints are taken into consideration, the scenario can successfully account for the observed magnetic fields as long as the energy scale of inflation is smaller than GeV, under some conditions on the slow roll of the auxiliary scalar field.
Information content in threshold data with non-Gaussian noise
Czech Academy of Sciences Publication Activity Database
Greenwood, P.E.; Lánský, Petr
2007-01-01
Roč. 7, č. 1 (2007), L79-L89 ISSN 0219-4775 R&D Projects: GA MŠk(CZ) LC554; GA AV ČR(CZ) 1ET400110401 Grant - others:NSF(US) DMS-0502349; NSA (US) H98230-1-0097 Institutional research plan: CEZ:AV0Z50110509 Keywords : Threshold model * stochastic resonance Subject RIV: BO - Biophysics Impact factor: 0.696, year: 2007
Energy Technology Data Exchange (ETDEWEB)
Ho, Shirley; Agarwal, Nishant; Lyons, Richard; Disbrow, Ashley; O' Connell, Ross [McWilliams Center for Cosmology, Department of Physics, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); Myers, Adam D. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Seo, Hee-Jong; Schlegel, David; Ross, Nicholas P. [Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA 94702 (United States); Ross, Ashley [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Portsmouth, PO1 3FX (United Kingdom); Hirata, Christopher; Huff, Eric; Weinberg, David [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Padmanabhan, Nikhil [Department of Physics and Astronomy, Yale University, New Haven, CT 06520 (United States); Slosar, Anže [Brookhaven National Laboratory, Bldg. 510, Upton NY 11375 (United States); Strauss, Michael; Bahcall, Neta [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Schneider, Donald P. [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States); Brinkmann, J. [Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349-0059 (United States); Palanque-Delabrouille, Nathalie, E-mail: shirleyh@andrew.cmu.edu [CEA, Centre de Saclay, Irfu/SPP, F-91191 Gif-sur-Yvette (France); and others
2015-05-01
The Sloan Digital Sky Survey has surveyed 14,555 square degrees of the sky, and delivered over a trillion pixels of imaging data. We present the large-scale clustering of 1.6 million quasars between z=0.5 and z=2.5 that have been classified from this imaging, representing the highest density of quasars ever studied for clustering measurements. This data set spans 0∼ 11,00 square degrees and probes a volume of 80 h{sup −3} Gpc{sup 3}. In principle, such a large volume and medium density of tracers should facilitate high-precision cosmological constraints. We measure the angular clustering of photometrically classified quasars using an optimal quadratic estimator in four redshift slices with an accuracy of ∼ 25% over a bin width of δ{sub l} ∼ 10−15 on scales corresponding to matter-radiation equality and larger (0ℓ ∼ 2−3). Observational systematics can strongly bias clustering measurements on large scales, which can mimic cosmologically relevant signals such as deviations from Gaussianity in the spectrum of primordial perturbations. We account for systematics by employing a new method recently proposed by Agarwal et al. (2014) to the clustering of photometrically classified quasars. We carefully apply our methodology to mitigate known observational systematics and further remove angular bins that are contaminated by unknown systematics. Combining quasar data with the photometric luminous red galaxy (LRG) sample of Ross et al. (2011) and Ho et al. (2012), and marginalizing over all bias and shot noise-like parameters, we obtain a constraint on local primordial non-Gaussianity of f{sub NL} = −113{sup +154}{sub −154} (1σ error). We next assume that the bias of quasar and galaxy distributions can be obtained independently from quasar/galaxy-CMB lensing cross-correlation measurements (such as those in Sherwin et al. (2013)). This can be facilitated by spectroscopic observations of the sources, enabling the redshift distribution to be
Diffusion and transport in locally disordered driven lattices
Energy Technology Data Exchange (ETDEWEB)
Wulf, Thomas, E-mail: Thomas.Wulf@physnet.uni-hamburg.de; Okupnik, Alexander [Zentrum für Optische Quantentechnologien, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Schmelcher, Peter, E-mail: Peter.Schmelcher@physnet.uni-hamburg.de [Zentrum für Optische Quantentechnologien, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany)
2016-09-15
We study the effect of disorder on the particle density evolution in a classical Hamiltonian driven lattice setup. If the disorder is localized within a finite sub-domain of the lattice, the emergence of strong tails in the density distribution which even increases towards larger positions is shown, thus yielding a highly non-Gaussian particle density evolution. As the key underlying mechanism, we identify the conversion between different components of the unperturbed systems mixed phase space which is induced by the disorder. Based on the introduction of individual conversion rates between chaotic and regular components, a theoretical model is developed which correctly predicts the scaling of the particle density. The effect of disorder on the transport properties is studied where a significant enhancement of the transport for cases of localized disorder is shown, thereby contrasting strongly the merely weak modification of the transport for global disorder.
Diffusion and transport in locally disordered driven lattices
International Nuclear Information System (INIS)
Wulf, Thomas; Okupnik, Alexander; Schmelcher, Peter
2016-01-01
We study the effect of disorder on the particle density evolution in a classical Hamiltonian driven lattice setup. If the disorder is localized within a finite sub-domain of the lattice, the emergence of strong tails in the density distribution which even increases towards larger positions is shown, thus yielding a highly non-Gaussian particle density evolution. As the key underlying mechanism, we identify the conversion between different components of the unperturbed systems mixed phase space which is induced by the disorder. Based on the introduction of individual conversion rates between chaotic and regular components, a theoretical model is developed which correctly predicts the scaling of the particle density. The effect of disorder on the transport properties is studied where a significant enhancement of the transport for cases of localized disorder is shown, thereby contrasting strongly the merely weak modification of the transport for global disorder.
DEFF Research Database (Denmark)
Borup Lynggaard, Aviaja
2006-01-01
This paper will examine how probes can be useful for game designers in the preliminary phases of a design process. The work is based upon a case study concerning pervasive mobile phone games where Mobile Game Probes have emerged from the project. The new probes are aimed towards a specific target...... group and the goal is to specify the probes so they will cover the most relevant areas for our project. The Mobile Game Probes generated many interesting results and new issues occurred, since the probes came to be dynamic and favorable for the process in new ways....